……………………. Edited by: A. Öchsner, G. Murch, A. Shokuhfar and J. Delgado
ABSTRACT BOOK DSL 2009 • ROME - ITALY 24‐26 JUNE, 2009 www.dsl2009‐rome.com
IRONIX CONFERENCES MANAGEMENT ironix-conferences.com
we organise conferences! DSL‐2009 / Rome ‐ ITALY ABSTRACT BOOK
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PREFACE It is our great pleasure to welcome you to the 5TH INTERNATIONAL CONFERENCE ON DIFFUSION IN SOLIDS AND LIQUIDS: MASS TRANSFER, HEAT TRANSFER, MICROSTRUCTURE AND PROPERTIES, NANODIFFUSION AND NANOSTRUCTURED MATERIALS, DSL 2009, in the ancient Rome ‐ Italy, from 24‐ 26 June, 2009. DSL‐2009 aimed at attracting a balanced portion of delegates from academia, industry and research institutions and laboratories involved with research and development work. In doing so, the conference provides a binding platform for academics and industrialists to network together, exchange ideas, provide new information and give new insights into overcoming the current challenges facing the academics and the industrialists relating to Mass Transfer, Heat Transfer, Microstructure and Properties, Nanodiffusion and Nanostructured Materials. I would like to thank the Organising Committee members and members of the Local Committe for their help in contributing to the successful organisation of this meeting and special thanks to Prof. Oronzio Manca for his support to help participants to get VISA’s from the Italian Embassies. I would like to thank the colleagues, organisers of the SPECIAL SESSIONS, Thank you! A special thanks to Professor Graeme Murch, Professor Ali Shokuhfar and Professor João Delgado, co‐ chairs of DSL‐2009, for the excellent work, significant inputs and support to this conference. Concerns have been expressed about the influenza (H1N1FLU), travel to Rome etc... However, in the middle of all questions without answers delegates did the way till here and I would like personally to thank all delegates for the decision in attending DSL 2009 hope you will find the meeting very useful for your work, business and a useful forum for obtaining new knowledge. Have fun learning and meeting new people! Be helthy and keep yourself helthy! See you again in 2010, in Paris! Professor Andreas Öchsner
DSL CONFERENCES – Chairman
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ORGANISING COMMITTEE
SCIENTIFIC COMMITTEE
Prof. Dr. Ing. A. Öchsner (chair) University of Malaysia, Malaysia Prof. Dr. G. Murch (co‐chair) The University of Newcastle, Australia Prof. Dr. A. Shokuhfar (co‐chair) K.N. Toosi University of Technology, Iran Prof. Dr. J. Delgado (co‐chair) University of Porto, Portugal
LOCAL COMMITTEE Prof. Dr. Oronzio Manca (Head of Local Committee) Seconda Universita' degli Studi di Napoli, Italy Dr. Giovanni Mazzolai University of Perugia, Italy Dr. Ing. Assunta Andreozzi Universita' degli Studi di Napoli Federico II, Italy Prof. Dr. Antonio Barletta Universita' di Bologna, Italy Prof. Dr. Nicola Bianco Universita' degli Studi di Napoli Federico II, Italy Dr. Bernardo Buonomo Seconda Universita' degli Studi di Napoli, Italy Dr. Ing. Gian Piero Celata ENEA, Italy Dr. Michele Celli Universita' di Bologna, Italy Prof. Dr. Nicola Massarotti Universita' degli Studi di Napoli Parthenope, Italy Prof. Dr. Sergio Nardini Seconda Universita' degli Studi di Napoli, Italy Prof. Ing. Vincenzo Naso Universita' degli Studi di Napoli Federico II, Italy Dr. Ing. Eugenia Rossi di Schio Universita' di Bologna, Italy Prof. Rosario Cantelli Università Degli Studi di Roma "La Sapienza", Italy
Prof. P. Pizani Prof. Y. Sohn Prof. I. Belova The University of Newcastle, University of Central Universidade Federal de Australia Florida, São Carlos‐UFSC, USA Brazil Prof. R. Bennacer Université de Cergy‐ Prof. B.B. Straumal Prof. R.V. Ramnath Pontoise, Massachusetts Institute Institute of Solid France of Technology‐MIT, State Physics, USA Russia Prof. B. Bokstein Moscow Institute of Steel Prof. M. Uematsu Prof. J.P. Rino and Alloys, Universidade Federal de Keio University, Russia São Carlos, Japan Brazil Prof. I.E. Campos Silva Dr. G. Roma IPN SEPI‐ESIME, Prof. M.A.J. Somers C.E. Saclay, Mexico Technical University of France Denmark, Prof. M. Danielewski Prof. Odila Florencio Denmark AGH University of Science UFSCAR, and Technology, Brazil Dr. Philippe Maugis Poland Arcelor Research SA, Dr. H. Fujikawa France Prof. A. N. Dmitriev Air Water Institute of Metallurgy of Incorporated., Prof. F. Coutelieris the Ural Branch of Russian Japan University of Ioannina, Academy of Sciences, Greece Russia Prof. Carlos Roberto Grandini Prof. R.F. Moreira Prof. A. Fishman UNESP/Bauru, Martínez Ural Department of Russian Brazil Universidade de Santiago Academy of Sciences, de Compostela, Russia L. S. Shvindlerman Spain University of Prof. A.A. Kodentsov Aachen, Prof. T.V. Morosuk Eindhoven University Germany Maritime University of Technology, Szczecin, The Netherlands Prof. Dezso L. Beke Poland University of Debrecen, Prof. Chan‐Gyu Lee Prof. M.E.R. Shanahan Hungary Changwon National University of Bordeaux, University, France Prof. Paul Heitjans Korea Leibniz University Prof. I.A. Wierszyllowski etal Forming Hannover Prof. W.O.F. Lengauer Germany Vienna University of Technology, Dr. Bernard AUFRAY Prof. I. Malico Austria CINaM‐CNRS Universidade de Évora France Portugal Prof. G. Mishuris Rzeszow University of Prof. M. Zinigrad Dr Gail R. Duursma Technology, Ariel University University of Edinburgh Poland Center of Samaria, Kings Buildings, Israel UK Prof. H. Nakajima Osaka University, Prof. V. Teixeira Dr. Eusebio Solórzano Japan University of Minho, University of Valladolid, Portugal Spain Prof. M. EL Ganaoui University of Limoges / CNRS, France Dr. Cornelia Breitkopf Technische Universität Bergakademie Freiberg Germany
Dr. Devendra Gupta IBM Thomas J. Watson Research Center, USA Prof. Huseyin Cimenoglu Istanbul Technical University, Turkey Prof. Toshitada Shimozaki Kyushu Institute of Technology, Japan Prof. Rafal Kozubski Jagellonian University, Poland Prof. Helmut Mehrer Universität Münster, Germany Prof. R. Shahbazian Yassar Michigan Technological University, USA Prof. G.J. Creus Universidade Federal Rio Grande Sul ‐ UFRGS, Brazil Dr. W. Eib Zika Leime, Germany Dr. Rodolfo Ariel Pérez Comisión Nacional de Energía Atómica (CNEA), Argentina Dr. J. Cermak Institute of Physics of Materials of the Academy of Sciences of the Czech Republic Prof. Yvan Houbaert Ghent University, Belgium Prof. M.J.S. De Lemos ITA, Brazil Prof. V. Popov Institute of Metal Physics, Russian Academy of Sciences, Russia Prof. S. Seetharaman Royal Institute of Technology, Sweden Prof. K. Sefiane The University of Edinburgh, UK
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6th
6TH INTERNATIONAL CONFERENCE ON DIFFUSION IN SOLIDS AND LIQUIDS: MASS TRANSFER, HEAT TRANSFER, MICROSTRUCTURE AND PROPERTIES, NANODIFFUSION AND NANOSTRUCTURED MATERIALS www.dsl2010-paris.com
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ADVANCED COURSE IN:
NANOSTRUCTURED MATERIALS MANUFACTURING, CHARACTERISATION AND APPLICATIONS
21‐23 September, 2009 THE RITZ CARLTON HOTEL Kuala Lumpur ‐ MALAYSIA
FOCUS 1:
‘Structural, Functional and Superhard Nano‐Structured Materials: scientific Fundamentals and Industrial applications’ LECTURER: Professor Dr. Dr. h.c. Stan Veprek Technical University Munich, Germany ……………………
FOCUS 2:
‘Advanced Materials Characterization Techniques: surface and structural analysis’ LECTURER: Professor Dr. Sam Zhang Nanyang Technological University, Singapore
……………………… WHO SHOULD ATTEND? Peoples from academia and industry working in the area of nanostructured materials are encouraged to attend this course to deepen and widen their knowledge. In addition, the course is designed for those who would like to start to work in the challenging area of nanotechnology. .................................. REGISTRATION FEE: 980 EUR * (*) Registration includes: • 3 full days course with two well‐ known Lectures, • Printed Course Materials, • Course Certificate, • 2 refreshments daily, • Lunch at The Ritz Carlton Hotel (daily / 3 days)
CONTACT: IRONIX‐ CONTINUING EDUCATION E‐mail: info@ironix‐conferences.com Fax: 00 755 37727 (IRONIX ‐ Malaysia) Contact person: Ms. Meire Gomes www.ironix‐conferences.com NOTE: this course is limited to a small number of participants, reserve your place soon!
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………………………………………………….. TABLE OF CONTENTS: 8 PLENARY LECTURES Experiments, theory and modelling of heat transport and fluid flow
12
Mass transport and related phenomena in metals and alloys
46
diffusion in amorphous materials
70
Mass transport and related phenomena in non‐metallic materials
73
Theory and modelling of mass transport and related phenomena
100
Industrial Applications of Mass Transport and Related Phenomena
134
Reactive Diffusion
177
Mass Transport and Related Phenomena in Natural Products and Pharmaceuticals
156
SPECIA SESSION:Heat and Mass Transfer in Porous Media
179
SPECIAL SESSION: Grain boundaries and interfaces: structure, thermodynamics and diffusion properties
219
SPECIAL SESSION: Heat Transfer in Cellular and Composite Materials
230
SPECIA L SESSION: Diffusion in Intermetallics
239
Characterization and Properties of Hard Coatings
258
SPECIAL SESSION: Microstructural Control Through Diffusion Processes
278
SPECIAL SESSION: Frontiers of Nanostructured Materials
298
SPECIAL SESSION ON: Microstructural Analysis and Properties of Materials
361
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Plenary Lectures
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DSL‐2009 Honorary Chairman VIP‐DSL008 Prof. B. Bokstein Moscow Institute of Steel and Alloys, RUSSIA
Opening Lecture: Diffusion at Short Circuits. State of the Art B.S. Bokstein
Evidence for solid‐state diffusion ( the second half of 19th century). The first measurements of solid state diffusion ( W.Roberts‐Austin(1896) – 1922). The first tracer experiments to determine the solid‐state diffusion (G.von Hevesy,1913 – 1923). The first evidence of accelerated diffusion in polycrystalline materials (1924 – 1935). Autoradiographic studies of grain boundary diffusion (50th of 20th century). The first quantitative experimental and theoretical studies of the “short circuiting” diffusion (beginning from 1949, D. Turnbull and R. Hoffman – General Electric Research Lab.): radiotracer serial sectioning method, Fisher’s model (1951)for grain boundary diffusion, exact solutions and developments of Fisher’s model (1954 – 1963). The progress in the experimental methods for determination of grain boundary diffusion data and results of measurements for different metallic systems ( up to date). The measurements of grain boundary diffusion parameters in B and C regimes. The measurements of diffusivities along migrating grain boundaries, dislocation pipes, low‐angle grain boundaries, phase boundaries, triple junctions of grains. Diffusion in thin films. Effect of gradient energy and stress. Grain boundary diffusion and grain boundary segregation. Nonlinear segregation effects. Structural effects of grain boundary diffusion. Diffusion in bicrystals. Diffusion in nanocrystals. Grain boundary wetting and grooving. Computer simulation of grain boundary diffusion Mechanisms of grain boundary diffusion Conclusion: where and why are we going?
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VIP‐DSL075 Prof. M.A. Dayananda Purdue University, West Lafayette, Indiana ‐ 47907, USA
Selected Analyses and Observations in Multicomponent Diffusion Selected isothermal diffusion studies in ternary and quaternary systems are reviewed in order to present analytical and experimental approaches adopted for the determination of interdiffusion fluxes of components, interdiffusion coefficients, diffusional interactions among components, and internal consistency in the experimental data. Several interesting phenomena and observations including uphill diffusion, zero‐flux planes and flux reversals, flux reversals at interfaces,nonplanar interfaces, demixing of phases, uncommon diffusion paths, and diffusion structure evolution are illustrated with selected single phase and multiphase diffusion couples in Cu‐based and Fe‐based ternary systems. The main challenges involved in the experimental determination of interdiffusion data from
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VIP‐DSL065 Prof. G.P. Celata ENEA, Energy Department, Institute of Thermal‐Fluid, Dynamics, Rome, Italy
Single and Two‐Phase Flow Heat Transfer in Micropipes Partly because of the technological challenge, partly because of stark necessity, there has been an increasing movement towards a miniaturization of appliances in the last decade. In all technical fields solutions are sought that encumber as little as possible without compromising on performance: in medical diagnostics, environmental sample analysis, military defence, consumer electronics, biomedical appliances, chemical reactors and heat management a constant research for quicker response times and portable devices has driven the field of microtechnology to impressive levels. In many applications it has been found that many small active components are more productive than few large ones, which is also in keeping with the growing trend towards modular design. Proper understanding of microscale transport phenomena is therefore fundamental for the designer of microfluidic devices. For this reason, many studies have been conducted to analyse the behaviour of convective flow through microchannels, both in single‐phase and in two‐phase flow. A first glance of the literature, especially for single‐phase flow, leads to the conclusion that up to now we have had an agglomeration of disparate conclusions. In many cases the experimental data in microchannels disagree with the conventional theory and empirical correlations, but they also appear to be inconsistent with one another. The present lecture is an attempt to critically analyse the available results for liquid single‐ phase and flow boiling heat transfer, trying to provide some sort of base note in the melisma of published data.
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Experiments, Theory and Modelling of Heat Transport and Fluid Flow
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DSL224 Dr. Imen Gaied Institut Préparatoire Aux Etudes d’Ingénieur de Nabeul IPEIN Merazka 8000 Nabeul, Tunisia
Investigation of optical and thermo‐electrical properties of SnSb2S4 thin layer using the Photothermal Deflection Technique Imen Gaied1, Abdelaziz Gassoumi2, Mounir Kanzari2 and Noureddine Yacoubi1 1Institut Préparatoire Aux Etudes d’Ingénieur de Nabeul IPEIN Merazka 8000 Nabeul‐Tunisie 2ENIT BP 37, le belvédère 1002 Tunis‐Tunisia Sulfosalt SnSb2S4 films have been deposed on glass substrates by thermal evaporation and subsequently thermally annealed in vacuum at temperatures from 100 to 200 °C. Below a transition temperature of 140 °C., the films are highly resistive with a dominant amorphous component, however above this temperature, the samples exhibit p+‐type semiconductor behavior with a dominant crystalline component .In this work we have studied the thermal and optical properties of these films using the photo thermal deflection technique. The thermal properties are determined by comparing the experimental amplitude and phase curves variations versus square root modulation frequency of the photo thermal signal to the corresponding theoretical ones. The best theoretical fitting curves are obtained for well‐defined values of thermal conductivity and thermal diffusivity. The optical absorption spectrum is obtained by comparing the experimental normalized amplitude of the photo thermal signal curves variations versus wavelength to the corresponding theoretical curves variations versus optical absorption coefficient. We have determined the energy gap by using the Tock law. From a measure of the sample’s resistance, one can deduce the electrical resistivity so the electrical conductivity which may be correlated to the thermal conductivity. ……………… VIP‐DSL042 Prof. J. P. Rino Departamento de Física, Universidade Federal de São Carlos Via Washington Luiz km 235, 13569‐080, São Carlos, SP Brazil
Equilibrium and non equilibrium Molecular Dynamics calculations of heat conduction in InSb Giovano de Oliveira Cardozo and José Pedro Rino Departamento de Física, Universidade Federal de São Carlos Via Washington Luiz km 235, 13569‐080, São Carlos, SP ‐ Brazil Thermal conductivity of materials at nanometrical scales is a prime subject of material sciences and engineering, mainly because of the large application of nanoscaled materials in microeletronics, where it is always necessary to combine high performance and low costs. In molecular dynamics there are two main ways to calculate thermal conductivity coefficients. The first is the equilibrium one, where the Fourier transformation of the heat current autocorrelation function, at zero frequencies limit, gives the thermal coefficient value (Green‐Kubo formula). The second method is the direct one, or non equilibrium, where a temperature gradient is imposed to the system, generating a heat current which is related to the gradient and to the thermal conductivity coefficient via Fourier law. Here it is shown the results for equilibrium and non equilibrium calculations of thermal conductivity coefficient in bulk systems of InSb using an effective two‐ and three‐body interatomic potential which has been very transferable. For equilibrium calculations a cubic system with 5 unit cells side, and consequently 1000 particles, and periodic boundary conditions in all directions, was used. The average heat current autocorrelation function was calculated for a 0.03ns time interval, which was long enough to stabilize the system, over 1000 independent runs. This procedure was repeated for 5 temperatures, 300K, 400K, 500K, 900K and 1000K, and the results were compared to experimental data.
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For non equilibrium calculations systems with 5x5xN unit cells, and periodic boundary conditions, with four different values of N, were used: 50 (resulting in 10000 particles), 200 (with 40000 particles), 400 (with 80000 particles) and 640 (with 128000 particles). The temperature gradient was imposed by adding and subtracting an amount of energy Δε respectively in a hot and a cold reservoir, placed in regions of the system separated by a distance L. In the stationary regime the temperature gradient between reservoirs is linear and its slope and the mean value of Δε are related to the thermal conductivity coefficient by the Fourier Law. In the limit of infinite length system, by extrapolation, this thermal coefficient tends to the correct value for the material under investigation. The temperatures in hot and cold reservoirs were fixed respectively at 250K and 350K for all systems. Simulations were made for at least 106 time steps, to reach stationary regime. Once stationary regime was reached, another run of 106 time steps, or 1,5ns, was proceeded to obtain the coefficient value. In these calculations in both cases, equilibrium and non equilibrium, the obtained results were comparable to the experimental data. For equilibrium calculations at 300K the coefficient value was about 10 W m‐1 K‐1, which is in good accordance with non equilibrium calculation, whose obtained value was about 16 W m‐1 K‐1. Both cases are in good agreement with experimental data of 15 Wm‐1 K‐1 reported by Magomedov and Bilalov.1 1‐ Y. B. Magomedov and A. R. Bilalov, Semiconductors 35, 499‐501 (2001). ……………… DSL528 Prof. Ivana Salopek Čubrić University of Zagreb, Faculty of Textile Technology, Prilaz baruna Filipovica 28a, 10 000 Zagreb, Croatia
The Simulation of Heat and Vapour Transfer Trough Fibrous Materials I. Salopek Čubrić, Z. Skenderi University of Zagreb, Faculty of Textile Technology, Prilaz baruna Filipovica 28a, 10 000 Zagreb, Croatia The heat and water vapour transmitting properties of fibrous materials are important factors that affect the clothing's comfort as well as the quality of special functional clothing that is worn in extreme environmental conditions. In order to maintain the total balance within the body, the role of fibrous materials is to contribute to the maintenance of the following equation: M ‐ W = R + C + E + L + K + S, where: M = total rate of energy production determined from the rate of oxygen consumption; W = rate at which external work is being performed; R = radiation; C = convection; E = evaporation; L= warming and wetting of air which is inhaled and then exhaled; K = conduction and S = rate of storage of heat in the body. The paper introduces advanced system for the simulation of physiological processes that appear next to the human skin. Its use enables the measurement of heat and vapour transfer trough fibrous structures, as well as determination of vapour permeability and permeability index. The experiments reported here refer to the measurement of a number of fibrous materials used for the next‐to‐skin wear. For the measurement have been produced materials that differ either in their structure or raw material in order to observe the influences of different parameters to the transfer properties. The transfer trough fibrous materials is mainly affected by its structure that comprises of a repeat units with cellular geometry containing air pores, yarns that form basic structure and intersection points of two or more yarns. Therefore, the structure of materials is also investigated and described by means of fabric moduli. Dynamics of heat and vapour transfer is observed through the experimentally obtained data and the influence of a number of structural parameters is discussed. The statistical methods are used to qualify the effects of investigated variables on the heat and vapour resistance. ……………… DSL042 Prof. Pavol Koštial Faculty of Metallurgy and Materials Engineering, Department of Materials Engineering, 17. listopadu 15/2172, 70833 Ostrava‐Poruba, Czech Republic
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Thermo ‐ Mechanical Material Analysis Pavol Koštial1, Ivan Ružiak2, Zdeněk Jonšta1, Miroslav Tvrdý1 1 Faculty of Metallurgy and Materials Engineering, Department of Materials Engineering, 17. listopadu 15/2172, 70833 Ostrava‐Poruba, Czech Republic 2 Institute of Material and Technological Research, Faculty of Industrial Technologies, University of Alexander Dubček in Trenčín, I.Krasku 491/30, 02001 Púchov, Slovak Republic
[email protected],
[email protected],
[email protected],
[email protected] The experimental system for complex thermo‐mechanical material analysis (CTMA) is presented in this paper. System provides measurement usual for tensile test as well as heat generation in the process of deformation. We measured the cooling curve of the sample after its deformation. On the basis of exponential model of cooling body with respect to Biot number (Bi ) value it is possible to calculate heat capacity cp [J/kgK], thermal diffusivity α [m2/s] and thermal conductivity λ [W/m.K].. The method had been tested on the variety of materials and the results were compared to those in charts or obtained by reference independent experiments. We obtained very good agreement of all obtained experimental results with those of comparative ones. ……………… DSL260 Dr. Rita Aguilar Osorio Instituto Politécnico Nacional – Sección de Estudios de Posgrado e Investigación Unidad Profesional Adolfo López Mateos. Edificio 5, 3er. Piso Col. Lindavista, C.P. 07738, Mexico, D.F.
Numerical Simulation of Heat Loss between a Partition Plate and the Wall of the Head of a Plastic Heat Exchanger R. Aguilar Osorio1 and K. Cliffle2 1Instituto Politécnico Nacional – Sección de Estudios de Posgrado e Investigación Unidad Profesional Adolfo López Mateos. Edificio 5, 3er. Piso Col. Lindavista, C.P. 07738, Mexico, D.F. E‐mail address:
[email protected] 2Department of Mechanical and Chemical Processes Engineering, Sheffield University. Mappin Street, Sheffield S1 3JD, UK For this research was considered that the heat exchanger was affected by leakage in the head across the partition plate and the wall between the tube passes. Leakage was a problem in the plastic shell and tube heat exchanger, because it was difficult to seal the partition plate to the head of the exchanger. The material used for manufacturing the heat exchanger was polyvinylidene fluoride, PVDF. In order to predict the amount of flow leaking through the clearances of the tube passes a numerical simulation was carried out using a computational Fluids Dynamics CFD Fluent Software. The results of this simulation were used to investigate if the flow leakage affected the heat transfer performance of the exchanger sufficiently to require improvement of the design. To obtain the percentage of the heat loss across the tube passes different clearance sizes between the partition plate and the wall of the head of the exchanger were analyzed, for 4 tube passes. For the smaller clearance size of 0.2 mm the heat transfer coefficient was reduced up to 15%. These results suggest that the flow mass bypassing the head between tube passes affect the results of the heat transfer coefficient and confirm the observed from the experimental results, that its performance was affected by leakage between tube passes. This research served as an extension of the preliminary plastic heat exchanger design. The leakage problem was overcome, in a current design, fixing the partition plate on the wall of the head and sealing very carefully the components of the heat exchanger. …………… DSL044 Dr. Hayder A. Abdul Bari Faculty of Chemical and Natural Resources Engineering, University Malaysia Pahang, Malaysia
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Glycolic Acid Ethoxylate 4‐Tert‐Butylphenyl Ether as Drag Reducing Agent in Aqueous Media Flow Hayder A.Abdul Bari1, Emma Suali1 and Zulkafli Hassan1 1Faculty of Chemical and Natural Resources Engineering, University Malaysia Pahang, Malaysia. 2Faculty of Pharmacy, International Islamic University Malaysia Glycolic acid ethoxylate 4‐tert‐butylphenyl ether was used as investigated anionic surfactants in this experimental work. A built up rig with ratio of pipe length to diameter (L/D) is equal to 59 was used to achieve the purpose of this work which to investigates the drag reduction in turbulent flow with different flow rates and concentration of additive. In a present study, the concentrations (ppm) of additive were analyzed starting from 200, 300, 400, 500 and 600, respectively. The flow rates (Re) of solution were from 11235, 22470, 33705, 44940, 56175, 67410 and 78645, respectively. It was found that glycolic acid ethoxylate 4‐tert‐butylphenyl ether capable to reduce drag less than 10 %. The highest drag reduction was achieved is 8 % in 600 ppm of solution for turbulent flow with Re within range 44940 to 56175. The results of experimental work shows that these anionic surfactants perform as a poor drag reducing agent due to its drag reduction values increases only 1 to 3 % even though the concentration of solution was added about 100 ppm. This is occurred probably because of the formation of micelle in solution is not in a fully threadlike forms. Keywords: Drag reduction; critical micelles concentration; turbulent flow; Anionic surfactants ……………… DSL276 Dr. R. Leticia Corral‐Bustamante Instituto Tecnológico de Ciudad Cuauhtémoc, Cuauhtémoc, Chihuahua, Av. Tecnológico S/N, Z.P. 31500, México
Heat Transfer in Black Holes R.L. Corral‐Bustamante*, D. Sáenz, N.I. Arana Instituto Tecnológico de Ciudad Cuauhtémoc, Cuauhtémoc, Chihuahua, Av. Tecnológico S/N, Z.P. 31500, México. *Corresponding author: E‐mail:
[email protected] Phone & Fax: +52 625 581 1707 Ext. 114. During modeling of gigantic masses in continuum space‐time, some of the solutions to the relativistic equations of Einstein give rise to singularities which allow predict heat transfer that it is originated in black holes of huge intensity of gravitational field [1]. A black hole is a thermodynamic system whose volume of control is bounded by the event horizon; the occurrence of heat transfer in its interior and its boundary can be expressed by the degree of disorder or entropy, which is indicative that black hole shows emissions. Therefore a black hole is not so black, due to the radiation produced. The electromagnetic emission of particles of the black hole to the surroundings can lead to its extinction or collapse. In this paper a metric is postulated starting from a entropy balance of a black hole as a thermodynamic system which contains the energy transport across the border, due to mass transfer, heat transfer and work, and the generation of entropy [2,3]. The relativistic equation obtained is treated as a quantum equation (quantum gravity). Of the calculations made in terms of general relativity and thermodynamics principles for huge masses, is presented evidence of a Big Bang probable: A principle of the universe through the singularity found, and it is clarified an expanding universe due to degree of disorder. [1] A. Ashtekar, V. Taveras, M. Varadarajan, Phys.Rev.Lett., 100, 211302 (2008). [2] J.L. Tane, J. of Theoretics, 2, 3 (2000). [3] J.L. Tane, J. of Theoretics, 3, 4 (2001). ……………… DSL150 Dr. Yogesh Jayant Bhalerao Maharashtra Academy of Engineering, Alandi (D), Pune, (MS), India
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Thermal Modeling of Wet Grinding Process by using Design of Experiments Y.J. Bhalerao1, S.R. Kajale2 1Maharashtra Academy of Engineering, Alandi (D), Pune, (MS), India. 2SGGS Institute of Engineering and Technology, Nanded, (MS), India. Grinding in general is a very complex material removal operation involving cutting as well as ploughing and rubbing between the abrasive grains and the work material. The high temperatures are major source of thermal damage on the machined surface. In the previous work a simple moving heat source model has been developed to estimate maximum workpiece surface and average workpiece surface temperature during surface grinding process in dry condition. The model is validated by using Design of Experiments (DoE) techniques. In this paper the previous model is further developed to find maximum and average workpiece surface temperature during surface grinding process in wet condition. Experimentation is done on ferrous as well as non – ferrous materials. Although widely used in industry, grinding remains perhaps the least understood of all machining processes. How it is applied is often depends upon the experience of the operator, rather than scientific knowledge. Despite the extensive research determining desirable operating parameters of grinding processes in an industrial setting often relies on operator’s skills and trial and error approach. This is due to the difficulty of transferring the laboratory based research results and available models to industrial practice where grinding set‐ups and parameters are different and also there is lack of the symmetrical tool to integrate various heterogeneous models and information. This research paper attempts to highlight and try to give solution for the same. [1] Malkin, S. and Guo, C. “Grinding Technology: Theory and applications of machining with abrasives” Second Edition, Industrial Press, New York, 2008. [2] Malkin, S. and Guo, C. “ Thermal Analysis of grinding” Annals of CIRP – Manufacturing Technology, Keynote Paper, Volume 56/2 (2007), pp. 760 – 782. ……………… DSL519 Dr. Sunil Kr. Jain University College of Engineering, Rajasthan Technical University, Kota‐324022, India
Correction Factor for the Estimation of Effective Thermal Conductivity of High Porosity Two Phase Systems 1Sunil Kr. Jain, 2Ramvir Singh 1University College of Engineering, Rajasthan Technical University, Kota‐324022, India 2Heat Transfer Lab, Department of Physics, University of Rajasthan, Jaipur‐302004, India The transport of heat across a porous system with either open or closed cells is dominated by conduction. Because of high porosity, these systems have large applications in lightweight structures, vibration control, energy management etc. Polyurethane and ceramic foams play an important role in thermal insulation applications like packing of food, chemical catalytic reactor and solar energy applications. On the other hand metallic foams like aluminum and titanium foams find use in erecting light structures where strength and toughness is important. These metal foams have better utilization in cooling towers, heat shielding in aircraft exhaust, high power electronic devices etc. For a variety of applications of these materials, study of their thermophysical properties is essential. The effective thermal conductivity of such systems is mainly dependent on porosity, thermal conductivity of constituent phases and morphology of cells. Single theoretical expression cannot provide the estimation for effective thermal conductivity for all kind of such systems and geometries, which exist in real physical systems. A theoretical expression for ETC of high porosity two phase systems presented here is based on equivalent thermal resistors formed out of phases in the form of parallel slabs and resistor model approach has been used. We propose and use a model to calculate effective thermal conductivity by taking into account the randomization of series and parallel arrangements of heat flux lines. To incorporate the interaction between phases, a correction factor has been introduced which has been developed by simulation of data available in the literature. This factor is correlated in terms of weightage of thermal conductivities with fractional volumes of the constituents. The expression for correction factor has
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been taken out in terms of thermal conductivities of solid and fluid phase for proper correlation with the involved phases. Later effective thermal conductivity is calculated by incorporating the correction factor for various samples of metallic foams and twophase highly porous system. The results so obtained are in resemblance with the available values of effective thermal conductivity for these high porosity systems. Keywords: Correction factor, Effective thermal conductivity, Porosity, Series and parallel resistors. ………………
DSL085 Dr. K. J. Singh Department of Physics, S.G. N. Khalsa P. G. College, Sri Ganganagar–335 001 INDIA
Computational Aspects of Effective Heat Storage Coefficient of Multi‐phase Systems K. J. Singh1 and Ramvir Singh2 1Department of Physics, S.G. N. Khalsa College, Sri Ganganagar (Raj.) – 335 001. 2Heat Transfer Laboratory, Department of Physics, University of Rajasthan, Jaipur ‐ 302 004, India. A theoretical model, to predict effective heat storage coefficient (HSC) from the values of HSCs of the constituent phases and their volume fractions for real two phase systems is presented, assuming an effective continuous medium (ECM), it is extended to three phase moist porous materials. Particles are assumed to be ellipsoidal in shape and arranged in three‐dimensional cubic array. The arrangement has been divided into unit cells, each of which contains an ellipsoid. The HSCs of the unit cell has been determined by applying resistor model. To take account of the non‐linear flow of heat flux lines in real systems, incorporating an empirical correction factor in place of physical porosity modifies an expression for HSC. An effort is made to correlate it in terms of the ratio of HSCs of the constituents and the physical porosity. To test the validity of the derived expression, the HSC of some building materials saturated with different liquids has been determined. A good agreement has been found between the experimental and the predicted values reported in the literature. Key words: Effective heat storage coefficient; effective continuous medium; porous media; correction factor ……………… DSL210 Mr. Yogesh Sonavane Otto von Guericke University, The Institute of Fluid Dynamics and Thermodynamics University platz 2, Post box 4120, Magdeburg, 39106 Germany
Numerical Modeling of the Rotary Kilns in the Industrial Processes by Using ANSYS (Finite Element Method) E. Specht1, Y.S. Sonavane2 1 Otto von Guericke University, The Institute of Fluid Dynamics and Thermodynamics University platz 2, Post box 4120, Magdeburg, 39106 Germany 2 Otto von Guericke University, The Institute of Fluid Dynamics and Thermodynamics University platz 2, Post box 4120,
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Magdeburg, 39106 Germany Heat transfer mechanism is complicated in case of rotary kiln as it includes conduction, convection and radiation at a same time. The heat transfer model has to be solved numerically because of the two‐dimensional problems which consider the thermal heat conduction in radial and circumferential direction. In order to predict and improve the evolution and the distribution of temperatures in the rotary furnace, a numerical analysis is undertaken using ANSYS 11 finite element package. The standard element type plane 55 for two dimensional thermal solids is used. A numerical simulation includes temperature distribution on the internal surface of the wall in order to improve the understanding of the heat transfer process across it. Analysis of the temperature distribution across the circumferential and radial direction, temperature fluctuation causes on the boundary conditions were studied thoroughly. All results clearly indicates the temperature distribution for different angular velocity and with different heat transfer coefficients under different filling degree. Penetration depth have been easily observed in on the radial side of the wall. Penetration depth is around 12 mm where all curve meet together. Only this thickness takes part in heat transfer process. Temperature at the solid side is decrease continuously and at the gas side it first increase because of regenerative heat phenomenon. Experimental results are qualitatively matches with the Numerical results. Temperature fluctuations increase with increase in rotational speed has been observed. ……………… DSL252 Prof. Mónica Oliveira Departamento de Engenharia Mecânica, Universidade de Aveiro, Campus Universitário de Santiago, 3810‐193 Aveiro, Portugal
Thermodynamic and Transport Properties of CNT Water Based Nanofluids J.Ponmozhi1, F.A.M.M.Gonçalves2, A.G.M.Ferreira2, I.M.A.Fonseca2, S.Kanagaraj3 and M.S.A.Oliveira1 1 Departamento de Engenharia Mecânica, Universidade de Aveiro, Campus Universitário de Santiago, 3810‐193 Aveiro, Portugal 2 Departamento de Engenharia Química, Universidade de Coimbra, Pólo II, Rua Sílvio Lima, 3030‐790 Coimbra, Portugal 3 Mechanical Engineering Department, IIT Kanpur, Assam, India Carbon nanotubes (CNTs) ‐ perhaps the most enticing class of nano‐materials are added in small volume fractions to enhance thermal properties of fluids when process intensification and device miniaturization are required. This work reports on the results obtained when measuring viscosity, surface tension, density and thermal conductivity of homogenous carbon nanofluids. The influence of CNTs volume concentration on the nanofluid thermo physical properties is studied and measurements are undertaken at different temperatures, ranging from 10ºC to 60ºC. The nanofluids were prepared by adding different volume concentrations of treated CNTs to water. The latter were sonicated for one hour and the colloidal stability was monitored with a UV‐spectrophotometer, the absorbance of the nanofluid was observed at 253nm, the average concentration of CNT was maintained at 9.35mg/l even after 200 hours, over 97% when compared with the initial concentration. As the volume concentration increases, the viscosity rises, for the same shear rate and temperature [1]. The viscosity was measured using a controlled stress rheometer .The measurements were performed in the shear rate ranging from 0 to 1200 sec‐1. The thermal conductivity was measured with a KD2 Pro thermal property tester from Decagon devices and the results show that thermal conductivity rises with CNTs concentration. A further steeper rise in thermal conductivity, for high volume percentages and higher temperatures, can be observed, being the results in accordance to those reported by [2, 3]. Therefore, it can be observed a thermal conductivity rise up to 45 % for CNTs concentration of 5% vol, when compared with its value for the base fluid water, between 10ºC and 30ºC, and a 70% increase for 40 and 50ºC up to 1% vol. Being results obtained, in close agreement with those obtained by Ding et al [3]. [1] G.H.Ko, K.Heo, K.Lee, D.S.Kim, C.Kim, Y.sohn, M.Choi, Int J Heat and Mass Transfer, 50,. 4749 (1990). [2] S.U.S.Choi, Z.G.Zhang, W.Yu, F.E.Lockwood, E.A.Grulke, Appl Phy Letts, 79, 2252 (2001). [3] Y.Ding, H.Alias, D.Wen, R.A.Williams, Int J Heat and Mass Transfer, 49, 240 (2006). ………………
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DSL302 Prof. Jose Alberto Reis Parise Pontifícia Universidade Católica do Rio de Janeiro, Rio de Janeiro, RJ, 22453‐900, Brazil
A Numerical Study on the Application of Nanofluids in Evaporators J.C.V. Loaiza, Y.R. Benito, F.C. Pruzaesky, J.A.R. Parise Pontifícia Universidade Católica do Rio de Janeiro, Rio de Janeiro, RJ, 22453‐900, Brazil The present paper is part of a broader project aiming at the characterization of heat pumps employing nanofluids. The addition of nanoparticles to liquids forms the nanofluids, which have shown to enhance significantly the heat transfer characteristics of the solution. In this work, a mathematical model is presented describing a straight double‐pipe horizontal evaporator, with refrigerant flowing through the annular section and the heat‐transfer fluid flowing through the inner tube. A multi‐zone model is employed. The evaporator is divided into two zones: boiling two‐phase and superheated vapor. Four different nanofluids are studied: H2O/Cu, H2O/CuO, H2O/Al2O3 and H2O/TiO2. Models for the determination of the thermodynamic and transport properties, as well as of the heat transfer and pressure droop mechanisms, were employed [1,2,3] to describe the nanofluids. Energy balances and heat‐transfer equations were applied to each zone of the heat exchanger resulting in a system of non‐linear equations. Results have shown that the use of nanofluids in evaporators as secondary fluids, reduced the required refrigerant volume, thus reducing its environmental impact. [1] S.P. Jang and S. Choi, Role of Brownian Motion in the Enhanced Thermal Conductivity of Nanofluids, Applied Physics Letters, 84, pp 4316‐4319, (2004). [2] V. Velagapudi, R.K. Konijeti, C.S.K. Aduru, Empirical Correlations to Predict Thermophysical and Heat Transfer Characteristics of Nanofluids, Thermal Science, 12, 2, pp 27‐37, (2008). [3] W.S. Heris, N.M. Esfahany, Gh.S. Etemad, Experimental Investigation of Convective Heat Transfer of Al2O3/water Nanofluid in Circular Tube, International Journal of Heat and Fluid Flow, 28, pp 203–210, (2007). ……………… DSL347 Dr. Kalaiselvam.S Department of Mechanical Engineering, Anna University Chennai, India – 600025
Application of Anodized/ Spray Pyrolysed Nanoporous Structure in Convective Heat Transfer Appliances Kalaiselvam.S*, Gugan.M.S, Kuraloviyan.E, Meganathan.R,Niruthiya Priyan.A, Swaminathan.M.R Department of Mechanical Engineering, Anna University Chennai, India – 600025 This paper investigates the augmentation of convective heat transfer by administering nanoporous layers formed by electrochemical anodization and spray pyrolysis. The control parameters of the fabrication process are studied to prepare a nanoporous layer with maximum porosity for heat transfer applications. The nanoporous layers formed are perused with the help of scanning electron microscope and atomic force microscope. Nanoporous structures formed on the metal surface enhance the capillary action which leads to considerable increment in convective heat transfer. The nanostructures formed on the surface aid in achieving the turbulence expeditiously. Nanoporous layers increment the heat transfer of polished bare metals with waviness 0.2 μm to a maximum of 133.3%. Outcome of experiments illustrate an impressive heat transfer augmentation of 58.3 % in etched metals of surface roughness 3 μm. Nanopores of size 75 to 95 nm formed by electrochemical anodization, and pores of size 40 – 50 nm formed by spray pyrolysis ameliorate the heat transfer by 130%. This imposes a greater impact in design of compact heat exchangers in chemical and power plants. A novel technology for effective utilization of thermal energy has been contrived and it has its potential applications in both active and passive heat transfer augmentation methods. Influence of pore size and flow velocity on convective heat transfer is also investigated with the help of compiled experimentation results.
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Keywords: Nanoporous surface, Electrochemical Anodization, Spray Pyrolysis, Convective heat transfer * Corresponding author. Tel.: +91 44 2220 3262. E‐mail addresses:
[email protected] (Kalaiselvam.S),
[email protected] (Gugan. M.S),
[email protected] (Kuraloviyan. E),
[email protected] (Meganathan.R),
[email protected] (Niruthiya Priyan. A),
[email protected] (Swaminathan. M.R) ……………… DSL420 Prof. Amedeo Amoresano Mechanical and Energetic Department, Naples University “Federico II” Via Claudio 21 80125 Italy
Identification of the Thermal Diffusivity of Automotive Compounds Tyres Using a LASER Source and IR Camera A.Cristophe1, A.Amoresano2, D.Giordano2, M.Russo2 1National Research Council , Naples Via Claudio 21 80125 IT 2Mechanical and Energetic Department, Naples University “Federico II” Via Claudio 21 80125 IT The operating temperature of the tires has a large influence on their performance in terms of handling and wear. With regard to handling, this basically depends on the tire‐road interaction or, precisely, on the forces that the tire is able to receive from the road and to pass to the vehicle. These interactions depend on the temperature, according to a law that is first increasing and then decreasing with the temperature. So exists, at least in theory, an optimal temperature, or rather a range of optimal temperatures that maximize the values of the forces exchanged by the way, fixed any other condition. The paper describes a new methodology to measure the thermal diffusivity of the automotive tires compound. This methodology uses a laser as thermal source to heat the surface of the insulated specimens taken from the tire. The knowledge of the thermal power of the laser beam, which heats a surface of the sample, and the laws of temporal temperature measured during the test by thermocouple and IR camera, allows identifying the diffusivity of the compound. ……………… DSL438 Mr. S.V.S.S.N.V.G.K.Murthy Department of Mathematics & Statistics, Indian Institute of Technology Kanpur, Kanpur‐208016, India
Darcy Natural Convection in a Non‐Newtonian Fluid Saturated Square porous Enclosure with a Wavy vertical Wall S. V. S. S. N. V. G. Krishna Murthy , B. V. Ratish Kumar2 1, 2 Department of Mathematics & Statistics, Indian Institute of Technology Kanpur, Kanpur‐208016, India. In this paper the Darcy natural convection process induced by an isothermal vertical wavy wall in a porous enclosure saturated with power‐law type Non‐Newtonian fluid is considered. The coupled non‐linear partial differential equations modeling such a free convection process are then solved by Finite element method. Numerical results illustrating the effects of the governing parameters such as Rayleigh number (Ra), power‐law index (n), number of waves per unit length (N), amplitude of the wavy curve modeling the wall (a), phase of the wavy curve (Ф), on the convection process are presented. The flow and temperature fields are analyzed through streamlines, isotherms and Local / Cumulative heat flux plots. [1] B.V. Rathish Kumar, P.V.S.N. Murthy, P. Singh, IJNMFI, 28(4), 633, (1998) [2] M.A. Hossain, D.A.S Rees, Acta Mechanica. 136, 133 (1999).
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[2] G.B. Kim, J.M. Hyun, Numerical heat Transfer, Part‐A: Applications, 45, 569 (2004). [3] B. V. R. Kumar, Shalini, Mohit Nigam, Vivek Sangwan, and S. S. N. G. K. Murthy (to appear) in Journal of Mechanics in Medicine and Biology, (2009). [4] Ching‐Yang Cheng, International Communications in Heat and Mass Transfer (2009). ……………… DSL511 Dr. Maximilian Serguei Mesquita Departamento de Engenharia e Ciencias Exatas – Dece Universidade Federal do Espirito Santo ‐ UFES, Sao Mateus, ES, 29933‐415, Brazil
Mixed Convection in a Vented Enclosure Filled with Square Rods and with an Isothermal Vertical Surface M.S. Mesquita1 and M.J.S. de Lemos2 1Departamento de Engenharia e Ciencias Exatas – Dece Universidade Federal do Espirito Santo ‐ UFES, Sao Mateus, ES, 29933‐415, Brazil 2Departamento de Energia – IEME Instituto Tecnologico de Aeronautica, Sao Jose dos Campos, SP, 12228‐900, Brazil This work presents a numerical study for mixed convection flow in an enclosure with an isothermal wall filled with square rods. Forced convection flow conditions are imposed by providing an inlet at the bottom of the isothermal surface, and a vent at the top, facing the inlet. Buoyancy is generated because of the difference in temperatures between the wall and the through stream. Comparisons are obtained by numerically solving a conjugate heat transfer problem that considers both the solid and the fluid space. Governing equations are solved using the finite volume method and the algebraic equation set is relaxed with the SIP procedure. The average Nusselt number at the hot wall, obtained from the cavity with square obstacles and for several Darcy numbers, are compared with those calculated with clean medium. ……………… DSL340 Mr. Wonjae Choi Graduate School, Dept. of Refrigeration & Air‐conditioning Engineering, Pukyong National University, Busan, 607‐739, Korea
Performance Characteristics of Capacity Control on Industrial Water Cooler Using PMV W.J. Choi1, H.W. Kim1, S.M. Baek1, H.J. Kang2, H.S. Lee3, J.I. Yoon3 1Graduate School, Dept. of Refrigeration & Air‐conditioning Engineering, Pukyong National University, Busan, 608‐739, Korea 2Duksan Cotran, Daegu, 702‐030, Korea 3College of Engineering, School of Mechanical Engineering, Pukyong National University, Busan, 608‐739, Korea Recently, technical trend for machine tools is focused on enhancing of speed and accuracy. For high speed and high accuracy, a thermal deformation must minimize in machine tools. To minimize the thermal influence, accuracy machine tools need to be adopted a cooling system with high precision. In this study, we suggest a high accuracy water cooling system using PMV (Pulse Modulation Valve) control. In this system, we use a compressor which is able to be driven in condition of unloading to improve the efficiency of PMV control. And a vapor refrigerant from the suction side of the compressor is injected back into the compressor suction side again using a solenoid valve. The PMV control can be used by this method. Also, by comparing with the existing ON‐OFF control method on identical operating conditions, we evaluated the efficiency and reliability of the new method. This method showed the shorter reaction time than that of the existing method. Also, the efficiency and
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performance improved by lower compressor work using the vapor injection without compressor stop. This result will be used for a basis data of comparative experiment with inverter control and manufacture of high accuracy water cooling system. Acknowledgments: This research was supported by Duksan Cotran and Small and Medium Business Administration (SMBA) of the Korean government. [1] M. Yaqub, S.M. Zubair, J.R. Khan, J. Energy, 25, 543 (2000) [2] C.P. Tso, Y.W. Wong, P.G. Jolly, S.M. Ng, J. International Journal of Refrigeration., 24, 543 (2004). [3] C.M. Kim, Y.J. Hwang, Y.H. Ryu and K.S.Cho, Conf. SAREK (2001). ……………… DSL354 Mrs. Naďa Beronská Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, Račianska 75, 831 02 Bratislava 3, Slovak Republic
Thermal Conductivity and Thermal Expansion of Copper Matrix Composites Reinforced with high modulus C fibres N. Beronská, P. Štefánik, K. Iždinský, Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, Račianska 75, 831 02 Bratislava 3, Slovak Republic Thornel K1100 high modulus carbon fibres combine large thermal conductivity (~ 900 ‐ 1000 Wm‐1K‐1) with very low coefficient of thermal expansion (‐1.5 x 10‐6 K‐1). Copper based composites reinforced with these fibres may yield quite unique combination of physical properties with thermal conductivity higher than that of pure copper and coefficient of thermal expansion as low as ~ 1 x 10‐6 K‐1. However due to no wetting in the Cu‐C binary system serious problems with the composite preparation need to be overcome when a pure Cu matrix is used. Moreover, unidirectional fibre alignment results in a large anisotropy of composite properties. Finally due to lack of chemical affinity there is no reaction interfacial bonding and the structural stability of the composite is in question. Gas pressure infiltration technique has been used to prepare copper based composite material unidirectionally reinforced with ~ 54 vol. % of Thornel K1100 carbon fibres. As‐received composite exhibited homogeneous distribution of fibres with some pores and voids in the inter‐ fibre locations. Thermal diffusivity was measured in longitudinal and transversal direction by the flash method and the measured data were fitted to a model which takes into account the finite flash duration. The thermal conductivity was calculated from the diffusivity measurements using calculated values of density and specific heat. Thermal expansion measurements were performed in 5 subsequent cycles at the heating/cooling rate of 0.05 °C/s up to the temperature of 600 °C in longitudinal and transversal directions. The structural stability of the composite was confirmed. Actually, in spite of weak bonding, there were no signs of any composite disintegration. The thermal diffusivity was not affected by the applied thermal cycling. ……………… DSL357 Mr. Hossein Davarzani Institut de Mécanique des Fluides de Toulouse (IMFT) Allée du Pr. Camille Soula, 31400 Toulouse, FRANCE
Tortuosity Effect on Thermal Diffusion Coefficient in Porous Media H. Davarzani, M. Marcoux, M. Quintard Institut de Mécanique des Fluides de Toulouse (IMFT) Allée du Pr. Camille Soula, 31400 Toulouse, FRANCE
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Thermal diffusion or Soret effect, which is the mass flux caused by a temperature gradient applied to fluid mixture, has been taken into account in many porous media applications, particularly in petroleum engineering and geophysics. In the literature, the effective macro‐scale diffusion coefficients are now well established [1], while uncertainty remains concerning the relationship between the effective thermodiffusion coefficient and micro‐scale parameters (such as pore‐scale geometry) [2]. Our previous study on theoretical model of effective thermal diffusion coefficient for a pure diffusion regime confirmed that the tortuosity factor acts in the same way on both Fick diffusion coefficient and on thermodiffusion coefficient [3]. In this study, new experimental results obtained with a two bulb apparatus are presented. The diffusion and thermal diffusion of a Helium‐Nitrogen system through cylindrical samples filed with glass spheres of different diameter are measured at the atmospheric pressure. Concentrations are determined by analysing the gas mixture composition in the bulbs with a Katharometer device. The results are in good agreement with theoretical results and emphasize the porosity of the medium influence on both diffusion and thermal diffusion process. [1] M. Quintard, L. Bletzaker, D. Chenu, and S. Whitaker, Chem. Eng. Sc., 61, 2643 (2006). [2] P. Costeseque, T. Pollak, J. K. Platten, and M. Marcoux, European Phys. J. E, Soft matter, 15 (3), 249 (2004). [3] H. Davarzani, J. Chastanet, M. Marcoux and M. Quintard, Lacture Note of the IMT8, Vol. 3, p.181, (Forschungszentrum jülich GmbH, Bonn, Germany, 2008). ……………… DSL195 Prof. Khairul Alam Department of Mechanical Engineering, Ohio University, Athens, OH 45701 USA
Development of Thermal Models Using Accurate 3D Geometry of Carbon Foam Khairul Alam and Mihnea Anghelescu Department of Mechanical Engineering, Ohio University, Athens, OH 45701 USA One of the potential applications of carbon foam is its use in thermal management, including convection heat transfer through its pores. However, because of the manufacturing process, the microstructure of carbon foam is quite complex, and the study of the relationship between its microstructure and bulk properties is a difficult problem. Several authors have used idealized geometries to derive the thermal properties based on the microstructure. However, the analytical models often produce results that are higher by a factor of two or more compared to experimental results. The objective of this study is to use an accurate three dimensional solid model of carbon foam microstructure to calculate bulk thermal properties. A specialized tool for the characterization of 3‐dimensional structures using automated serial sectioning and light microscopy is used to produces a solid model for analysis by the finite element method (FEM). The analysis of this true geometry demonstrates that the idealized models tend to overestimate the thermal conductivity of the carbon foam. ……………… DSL279 Mr. Adrian Circiumaru Faculty of Mechanics, “Dunărea de Jos” University, Galați, 800008, România
Thermal conductivity of fabric reinforced filled epoxy matrix composites G. Andrei, I.‐G. Bîrsan, A. Cîrciumaru, N. Diaconu Faculty of Mechanics, “Dunărea de Jos” University, Galați, 800008, România Tailoring the electro‐magnetic properties of PMC is one of the most important aims in composites researches. One of the most common solutions is to fill the composite’s matrix with various powders [1]. In this case the dimensions of filler’s particles are important while they determine the dimensions of interface changing not only the electro‐magnetic properties but also the mechanical and thermal properties. When a PMC is designed the properties of reinforcement, fillers and polymer have to be taken into account [2]. The current research is focused in showing the influence of filled polymeric layers over the properties of fabric reinforced composite. Both carbon fiber fabric and kevlar and carbon fiber fabric were used as
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reinforcements. The symmetry of filled polymeric layers was changed in order to point out the influence of fillers over the composite’s properties and to investigate the possibility of modifying the electro‐magnetic properties form the surface to the mid‐plan of the sample. The multi‐component composites could represent the cheapest solution when controllable properties are required. In order to establish the right amount of filler it is necessary not only to analyze the electromagnetic and mechanical properties but also the thermal properties [3, 4]. Thermal conductivity of pseudo‐laminate composites was investigated using the DSC technology. Also, thermal conductivity of single reinforcement layer immersed in filled epoxy was evaluated for various concentrations of fillers in order to start a data base with information regarding the relationship between the thermal conductivity of a layer and thermal conductivity of layered material. [1] S. M. Abbas, M. Chandra, A. Verma, R. Chatterjee, T. C. Goel, Composites : Part A, 37, 2148 (2006). [2] J. Shen, W. Huang, L. Wu, Y. Hu, M. Ye, Composites: Part A, 38, 1331 (2007). [3] Y. Xu, G. Ray, B. Abdel‐Magid, Composites: Part A, 37, 114 (2006). [4] M. Mulle, R. Zitoune, F. Collombet, P. Olivier, Y.‐H. Grunevald, Composites: Part A, 38, 1414 (2007). ……………… DSL332 Dr. M. Javad Maghrebi Mechanical Engineering Faculty, Shahrood University of Technogy, Shahrood, Iran
A High Order Time Advancement Scheme for Prediction of Solidification Processes A. Abbas Nejad*1, M.J. Maghrebi1 and H. Basirat Tabrizi2 1Mechanical Engineering Faculty, Shahrood University of Technogy, Shahrood, Iran 2Mechanical Engineering Faculty, Amirkabir University of Technogy, Tehran, Iran Transient heat transfer problems involving melting and solidification have an important role in many engineering applications. In general terms, there are two numerical approaches used in solving solidification problems: fixed grid and deforming grid. Enthalpy methods have been a popular means of numerically solving phase change problems. A major reason for this is that an enthalpy formulation removes the need to satisfy conditions on the moving boundary, which means that fixed grid solution can be used. The numerical solution of enthalpy method is investigated by several authors. Voller and Cross [1] used control volume technique for this method. Voller [2] applied implicit enthalpy method for metals and alloy solidification. Crowley and Ockendon [3] and Wilson et al. [4] simulated alloy solidification using enthalpy method. Recently Krabbenhoft et al. [5] solved phase change problems using an implicit mixed enthalpy‐temperature method. The first order forward scheme and central space finite difference was used for time advancement and spatial derivative modeling. In this paper we applied a third order compact Runge‐Kutta method for time advancement with second order central space finite difference for space derivatives to increase the accuracy of numerical solution. The results are compared with analytical and semi‐analytical solution in the literature for both pure and alloy materials. [1]‐ Voller, V.R. and Cross, M. "Accurate solutions of moving boundary problems using the enthalpy method", int. J. Heat Mass Transfer, Vol. 24, pp. 545‐556, 1981. [2]‐ Voller V.R., "An implicit enthalpy solution for phase change problems: with application to a binary alloy solidification", Appl. Math. Modelling, Vol. 11, pp. 110‐116, 1987. [3]‐ Crowley, A.B. and Ockendon, J.R., "On the numerical solution of an alloy solidification problem", Int. J. Heat Mass Transfer, Vol. 22, pp. 941‐947, 1979. [4]‐ Wilson, D.G., Solomon, A.D. and Alexiades, V., "A model of binary alloy solidification", Int. J. Numer. Meth. Engin., Vol. 20, pp. 1067‐1084., 1984. [5]‐ Krabbenhoft K., Damkilde L. and Nazem M., "An implicit mixed enthalpy–temperature method for phase‐change problems", Heat Mass Transfer, Vol. 43, pp. 233‐241, 2007. ………………
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DSL115 Mr. Mohammad Reza Mobinipouya Department of Chemistry, Firouzabad Islamic Azad University, Firouzabad, Iran
Turbulent free convection utilizing seven binary gas mixtures Mohammad Reza Mobinipouya1, and Mohammad Mehdi Papari2, Antonio Campo3,Mohsen Azari4 1Department of Chemistry, Firouzabad Islamic Azad University, Firouzabad, Iran email: mobinipouya @yahoo.com 2Department of Chemistry, Shiraz University of Technology, 71555‐313, Shiraz, Iran email:
[email protected], Fax: 98‐711‐735‐4523 3Department of Mechanical Engineering, University of Vermont, Burlington, Vermont, USA 4Department of Chemistry, Firouzabad Islamic Azad University, Firouzabad, Iran Keywords: turbulent boundary layers, free convection, binary gas mixture For turbulent free convection utilizing binary gas mixtures instead of air, the impact that the four participating thermo‐ physical properties ηmix, λmix, Cp,mix, and ρmix exerts on the allied convective coefficient hmix, /B conjoined to several body configurations may be summarized as follows. Among the seven helium‐based binary gas mixtures at a low film temperature of 300 K linked to Eq. (1), He‐CF4 gas mixture turns out to be the better binary gas mixture. It is firmly believed that the theoretical results of this technical present paper may be useful for the efficacious design of cooling processes involving turbulent free convection. When contrasted against air or helium, the degrees of freedom that the He‐based binary gas mixtures bring forward may lead to substantial reductions in the size and/or weight of the engineering devices. The present paper investigates a promising avenue for the intensification of turbulent free convection in various configurations using adequate binary gas mixtures in which (He) is the primary gas component and carbon dioxide (CO2), methane (CH4), nitrogen (N2), oxygen (O2), xenon (Xe), tetrafluoromethane (CF4) and sulfurhexafluoride (SF6), are the secondary gas components. Using micro scales of turbulence, Arpaci and Larsen[3] demonstrated that the convective coefficient h for turbulent free convection in gases owing Prandtl number Pr~1 responds to the proportionality 2 hm ⎛ λ3 × ρ 4 × C P = ⎜⎜ B ⎝ η2
1
⎞5 ⎟ ⎟ ⎠
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References [1] G.D. Raithby, K.G.T. Holland’s, Chapter 6, in: W.M. Rohsenow, et al., (Eds.), Handbook of Heat Transfer Fundamentals, McGraw‐Hill, New York, 1985. [2] T. Misumi, K. Kitamura, JSME Int. J. 36 (1993) 143. [3] V. Arpaci, P.S. Larsen, Convection Heat Transfer, Prentice‐Hall, Englewood Cliff, NJ, 1984 [4] A.E. Bergles, Chapter 10, in: W.M. Rohsenow, et al., (Eds.), Handbook of Heat Transfer, McGraw‐Hill, New York, 1973 ……………… DSL288 Mr. Zamoum Mohammed Faculté des Sciences, Département de physique, Université de Boumerdès, 35000, Tunisia
Energy Dissipation without Friction of Gas Bubble
1
M. Zamoum1 and M. Kessal2 Faculté des Sciences, Département de physique, Université de Boumerdès, 35000. 2 Faculté des Hydrocarbures et de la Chimie, Université de Boumerdès, 35000. E‐mail:
[email protected]
A gas bubble in a liquid medium is modeled by the Rayleigh‐Plesset equation [1], coupled with energy conservation and heat transfer by convection relation [2]
2
⎛ d 2 R ⎞ 3 ⎛ dR ⎞ g dV dU R⎜⎜ 2 ⎟⎟ + ⎜ +q+ = 0 and q = HA(T − T∞ ) ⎟ = 0 (P − P∞ ) , P ρ dt dt ⎝ dx ⎠ 2 ⎝ dx ⎠ The numerical resolution of this system is performed by a fourth order Runge‐Kutta method. The obtained results show the convection heat transfer coefficient effect on the bubble radius (Figure1 and Figure2)
Nomenclature R bubble radius. V volume of bubble. A area of bubble. T temperature T∞ ambient temperature. H convective heat transfer coefficient q heat transfer rate. U internal thermal energy P pression of bubble P∞ ambient pression g0 newton’s constant ρ density. Bibliographies [1] La Cavitation, Mécaniques et Physique et Aspects Industriels. Presses Universitaire de Grenoble [2] Introduction to unsteady thermofluid mechanics, Frederik J. Moody; A WILLY INTERSCIENCE 1990
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1 H=100 0.8 0.6 0.4
R
0.2 0 -0.2 -0.4 -0.6 -0.8
0
2
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Figure2. Gas bubble oscillation for adiabatic case (H=0) ……………… DSL439 Dr. Anil Kumar Shrotriya Department of Physics Seth Motilal (P.G.) College JHUNJHUNU‐333001 Rajasthan, India
Estimation of Heat Storage Coefficient of Multi‐phase Systems Using a New Developed Resistor Model A. K. Shrotriya Department of Physics, Seth Motilal (P.G.) College, JHUNJHUNU‐333001 Rajasthan, India The thermal properties of interest are the thermal conductivity λ, the thermal diffusivity α and specific heat c. Since these three quantities are inter‐related, (α = λ /ρc, where ρ is density). Knowledge of any two determines the third. Besides the three thermo physical coefficients needed to describe the thermal status of a substance, the heat storage coefficient (HSC) β
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is an additional useful parameter to describe its thermal behaviour. Although its value is related to the three constants β=√ λρc in many cases it behaves as an independent characteristic of the sample. The various factors which generally affect the HSC of materials are: • chemical composition • physical texture • temperature • pressure • heat flow In addition to providing reliable HSC data, it is desirable to find a correlation, empirical or otherwise between the HSC and other easily measured parameters such as porosity, formation factor, etc. In this paper, the HSC of different type of soil materials like dry dune sand, marble stone powder, surkhi sand, dry cement, loamy soil, lime stone powder and ash have been studied experimentally as well as theoretically for two‐phase systems. The determination of HSC of three phase systems has also been done using liquid‐air‐solid phase systems by adding water content and tertiary amyl alcohol as a liquid in two‐phase systems. In this model porosity and particle size plays an important role. The plane heat source method was used for the measurement of HSC of these materials. The experimental data and estimated values are so close and verify the success of model for these types of multi‐phase systems. The main considerations that motivated to undertake this study are – These materials are naturally abundant and are commonly used in building construction. The knowledge of thermo‐physical properties of sand and ash has importance in agriculture. The HSC parameter has not been much investigated so far. If the HSC of these materials at low interstitial air pressure is comparable to the HSC of silica and glass wool, these cheaper materials may possibly replace the costly and hazardous insulation in huge installation. Field solar ponds are surrounded with soil and concrete. The heat storage efficiency of power generation of these ponds depends upon the heat losses from the pond through these materials. It is also important from energy storage point of view, to have the knowledge of HSC of these materials with moisture content and temperature. ……………… DSL014 Prof. Oleg Pursky Kyiv Taras Shevchenko University, Kyiv UA‐03022, Pr. Glushkova 6, Ukraine
Thermal Expansion Effect on Heat Transfer in Orientationally‐Disordered Phases of Molecular Crystals O.I. Pursky1, V.A. Konstantinov2 1T. Shevchenko Kyiv National University, Department of Molecular Physics, 6, Glushkov Ave., Kyiv 03680, Ukraine 2B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Science of Ukraine, 47 Lenin Ave., Kharkov 61103, Ukraine In present study, an attempt has been made to find a thermal expansion effect on heat transfer processes in orientationally‐ disordered (OD) phases of molecular crystals. Discrepancies in temperature dependences of isobaric and isochoric thermal conductivity are connected with the thermal expansion of samples under investigation in isobaric case. To estimate the influence of thermal expansion on the heat transfer in OD phases of molecular crystals, in the present investigation we have undertaken to separate the phonon‐phonon and phonon‐rotation contributions to the total thermal resistance of solid SF6, CCl4(Ib) and C6H6, in both the isobaric and isochoric cases. For calculations, we used the modified version of reduced coordinates method [1]. It is important to note that, in this case, there is no need to resort to some approximation model or other. On the basis of our studies it seems justified to conclude that in OD phases of molecular crystals the thermal expansion effect tends to increase in phonon‐phonon component and general decrease in phonon‐rotational components of the total thermal resistance.
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[1] O.I. Pursky, N.N. Zholonko, and V.A. Konstantinov, Low Temp. Phys. 29, 771 (2003). ……………… DSL046 Mr. Afshin Farahbakhsh Islamic Azad University, Quchan Branch, Iran
Connection of Single‐Wall Carbon Nanotube to Au Layer as a Matrix for Biosensors A. Farahbakhsh1,a, H. A. Zamani2,b, S. K. Rahimi1, A. Niazmand1,c 1Department of Chemical Engineering, Quchan branch, Islamic Azad University, Quchan, Iran 2Department of Applied Chemistry, Quchan branch, Islamic Azad University, Quchan, Iran
[email protected], b
[email protected], c
[email protected] Keywords: single‐walled carbon nanotubes, glucose, glucose oxidize, biosensor In this work, the connection of the single‐wall carbon nanotube (SWCN) to Au layer by chemical vapor deposition (CVD) was investigated. The best arrangement of SWCN on Au layer was obtained the shoulder structure. In this arrangement, the iron nanoparticle was used as a base for the growing of Au/SWCN. The properties of the created Au/SWCN were characterized by the scanning electron microscopy (SEM) technique. The constructed Au/SWCN has 2‐4 nm diameter and 10‐15 µm length. This system can be use as a suitable matrix for the fabrication of a variety of biosensors. ……………… DSL201 Mr. M. Pirmohammadi Research Management of R &D Deputy, Mapna Group, Tehran, Iran
Effect of Variable Thermal Conductivity on Magneto‐Convection inside a Partitioned Enclosure M.Pirmohammadi1, M. Ghassemi2 1Research Management of R &D Deputy, Mapna Group, Tehran, Iran 2 Mechanical Engineering Department, KNToosi University of Technology, Tehran, Iran It is well known that natural convection heat transfer can be damped with the help of a magnetic field. Employment of an external magnetic field has increasing applications in material manufacturing industry as a control mechanism since the Lorentz force suppresses the convection currents by reducing the velocities. Study and thorough understanding of the momentum and heat transfer in such a process is important for the better control and quality of the manufactured products [1‐3]. Magneto‐convection in a differentially heated enclosure with two rectangular adiabatic ribs, symmetrically located on horizontal walls (adiabatic walls), is carried out.Thermal conductivity of fluid is temperature dependent. The governing non‐ linear equations are solved in a two‐dimensional domain using a control volume method and the SIMPLER algorithm for the velocity–pressure coupling is employed. The results will be are presented in form of streamlines, isotherms as well as Nusselt number for various Rayleigh number (Ra) and Hartmann number (Ha). The heat transfer across the cavity from hot wall to cold wall becomes poor for a decrease in k and also Suppression of conduction near hot wall is more than that of convection. Furthermore the as Ha increases the convection heat transfer suppresses and Nusselt number decrease. [1] I. E. Sarris a; G. K. Zikos A. P. Grecos a; N. S. Vlachos, Numerical heat transfer, Part B, 50, 158‐180 (2006) [2] M. Ghassemi, M. Pirmohammadi, GH. A. Sheikhzadeh, 24th Annual Review of
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Progress in Applied Computational Electromagnetics, (2008). [3] M. Pirmohammadi, M. Ghassemi, and GH. A. Sheikhzadeh, IEEE Transactions on magnetics, 45(No.1), 407‐411 (2009). Progress in Applied Computational Electromagnetics, (2008). [3] M. Pirmohammadi, M. Ghassemi, and GH. A. Sheikhzadeh, IEEE Transactions on magnetics, 45(No.1), 407‐411 (2009). ……………… DSL201 Mr. M. Pirmohammadi
Numerical Simulation of Natural Convection in a Mold M.Pirmohammadi1, G.A.Sheikhzadeh2, M.Hamedi3 1Research Management of R &D Deputy, Mapna Group, Tehran, Iran 2 Mechanical Engineering Department, University of Kashan, Kashan, Iran 3 Mechanical Engineering Department, University of Tehran, Tehran, Iran Natural convection heat transfer in differentially heated, partitioned cavities are encountered in various industrial applications, such as solidification in casting and crystal growth, heating and ventilating of living spaces, fire in buildings, and solar thermal collector systems. In many applications, for some reasons, attaching rib(s) or baffle(s) to the vertical wall or to the horizontal wall(s) partitions the cavity. Recently studies of heat transfer and fluid flow characteristics of partitioned cavity have come under scrutiny both numerically and experimentally [1‐3]. Numerical study of natural convection heat transfer inside a differentially heated square cavity with adiabatic horizontal walls and vertical isothermal walls is investigated. Two insulated ribs are symmetrically located on horizontal walls. The governing nonlinear equations are solved in a two‐dimensional domain using a control volume method and the SIMPLER algorithm for the velocity–pressure coupling is employed. The results will be are presented in form of streamlines, isotherms as well as Nusselt number for Rayleigh number ranging from 104 up to 105. Special emphasis is given in the systematic analysis to detail the effects of the length of the ribs on the flow structure and isotherm pattern. It is found that the mean Nusselt number is affected by the length of the ribs and Rayleigh number. [1] A. N. Khalifa, Energy conversion and management, 42,491‐504 (2001) [2] M. Ghassemi, M. Pirmohammadi, GH. A. Sheikhzadeh, WSEAS TRANSACTIONS ON FLUID MECHANICS, 2, 61‐68 (2007) [3] M. Pirmohammadi, M. Ghassemi, GH. A. Sheikhzadeh, ASME 2008 Summer Heat Transfer, August 10‐14 (2008), Jacksonville. FL. USA ……………… DSL217 Dr. I. I. Hadzhidimov Technical University, Varna, Bulgaria
Heat Turbomachines around‐Disk Spaces Mass and Heat Transfer Modeling R.D. Yosifov1, N.A. Lazarovski1, D.G. Rusev1, I.I. Hadzhidimov1, D.P. Chakyrova1 1Technical University, Varna, Bulgaria Heat turbomachines thermo‐aerodynamic processes analysis is important for their design and exploitation connected with reliable and failureless operation in a wide power range. The kinematic and thermodynamic parameters distribution of the work fluid around heavy loaded turbine disks and labyrinth seals causes considerable influence upon the heat exchange and energy convertion processes. This influence appears in several basic directions. The subject of the present paper is mass and heat transfer process analysis, connected with work fluid motion in typical complex clearances between rotor and stator of different steam turbines types. Mass transfer by flow kinematic parameters, consumption performances and resistances in the axial and radial clearances is determined. These parameters are aroud disks, diaphragms, internal and external labyrinth
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seals, drums, equilibrium piston (dummis), etc. for different turbine construction elements. By means of pumping, ejecting, reactive complex effects with variable boundary conditions the mass balance has been realized. This balance results on equilibrium pressures of streamlined turbine part. These pressures are individual for every exploitation regime in accordance with the necessary power connected with mass consumption, steam distribution, seals wearing out degree, etc. The pressures differences before and after the turbine disks and other unequilibrium rotor surfaces permit determining the inconstant axial bearing loadings. The bearing works under high hydraulic pressures in lubricate layer controlled by turbine protection and regulation system. Thermal turbine rotor load and expanding depending on temperature and velocity distribution of above mentioned clearances are calculated. This results on the convective heat transfer from the work fluid to the rotor elements and conductive transfer through the rotor (disks‐seals‐bearing modulus). The nonuniform temperature field is a significant factor acting by thermal expansions on axial loaded rotor system. Prognosis of thermal tension turbine rotors statement is a worldwide applied practice. Based on our regional conditions by means of axial forces and thermal expansions distribution determination it is possible to estimate the turbo‐aggregates performance reliability during design or reconstruction as well as the exploitation time within the total power range. ……………… DSL235 Mr. Valerio Tomarchio Alma Mater Studiorum,Università di Bologna, Dipartimento di Ingegneria Energetica, Nucleare e del Controllo Ambientale (DIENCA),Laboratorio di Montecuccolino, Via dei Colli 16. 40136 Bologna. Italy
MHD Mixed Convection in a Vertical Circular Duct with a Periodic Wall Temperature V. Tomarchio1, A. Barletta1 1Alma Mater Studiorum ‐‐ Università di Bologna, Dipartimento di Ingegneria Energetica, Nucleare e del Controllo Ambientale (DIENCA), Laboratorio di Montecuccolino, Via dei Colli 16. 40136 Bologna, ITALY In the last years, a growing interest has been addressed to the study of magnethydrodynamic effects on mixed and natural convective flows. Such interest in the topic is due to the large number of possible technological applications, like in metallurgy, where the quality of the materials, produced in a regime of controlled crystal growth, can be influenced by the effects of an external imposed magnetic field. Recently, being increased the efforts towards the realization of nuclear fusion machines; MHD effects in liquid metal flows are studied to design properly critical components (blankets) of experimental reactors. This paper describes the effects of a uniform horizontal magnetic field on the mixed convective flow of a conductive fluid in a vertical circular duct. The study hereby presented assumes a steady periodic regime induced by the wall temperature of the duct, which is uniform and varying sinusoidally with time. The local balance equations of momentum and energy, together with the conservation of electric charge, will be solved numerically. The temperature, velocity and electric potential fields will be decomposed in a steady and an oscillating component evaluated separately. The duct walls will be assumed as perfectly insulating. This paper continues the experience previously gathered in the analysis of mixed convection in steady‐periodic regime with and without MHD effects [1, 2]. [1] A. Barletta, E. Zanchini, Time‐periodic laminar mixed convection in an inclined channel, Int. J. Heat and Mass Transfer, 46, pp. 551‐563, 2003. [2] V. Tomarchio, A. Barletta: Effetti MHD sulla convezione mista entro un canale rettangolare in regime periodico stabilizzato, Atti del XXVI Congresso Nazionale UIT, 335‐‐340 (Palermo, 2008). ……………… DSL240 Dr. Ghanbarali Sheikhzadeh
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Mechanical Engineering Department, University of Kashan, Kashan, Iran
Effect of a Shield on Mixed Convection in a Rectangular Enclosure with Moving Cold Side Walls and a Heat Source on the Bottom Wall GH.A.Sheikhzadeh1, S.H.Moosavi1, N.Sadooghi1 1 Department of Mechanical Engineering, University of Kashan, Kashan, Iran The electronic components are treated as heat sources embedded in flat surfaces [1]. A number of numerical studies have been carried out to investigate the mixed convective cooling of heat dissipating electronic components, located in a rectangular enclosure and cooled by an external flow of air [2–4]. In this work, the mixed convention of air inside a rectangular cavity is studied numerically. The cavity has cold sidewalls moving at a constant speed. A constant flux heat source is attached to the bottom wall of the cavity. A thin thermal shield is located at a specific distance above the heat source. The top and the remaining parts of the bottom walls are adiabatic. The governing equations are solved using appropriate numerical methods. To solve for the velocity and pressure field the SIMPLER algorithm has been employed. The resulting set of algebraic equations has been solved using a line by line iteration and TDMA scheme. The results are presented in the form of streamline and isotherm contours. The Richardson number has been chosen as a criterion to monitor the effects of sidewalls velocities on the flow field and heat transfer inside the cavity. A parametric study has been conducted and the effects of heat source length, its location and the shield distance from the source on the heat transfer have been investigated. The results show that the heat dissipation increases as the heat source and the shield are moved up to a certain distance towards either side wall. However, moving them beyond this limiting distance results in the reduction of heat dissipation. It is shown that the presence of shield results in the reduction of the heat transfer coefficient. However, for the normalized distance of the shield from the heat source greater than 0.45, the shield’s effect on the reduction of the heat transfer coefficient is less than 10%. Keywords: Numerical Study, Rectangular Cavity, Heat Source, Mixed Convection, Shield [1] F.P. Incropera, J. Heat Transfer, 110, 1097, (1988). [2] E. Panpanicolaou, Y. Jaluria, Numer.Heat Transfer, Part A 23, 463, (1993). [3] E. Panpanicolaou, Y. Jaluria, J. Heat Transfer, 116, 960, (1994). [4] G. Guo, M.A.R. Sharif, International Journal of Thermal Sciences, 43, 465, (2004). ……………… DSL267 Prof. Gilmar Guimarães Federal University of Uberlândia, FEMEC‐UFU, Uberlândia, MG, Brazil
Analysis of the Effect of Cutting Parameters on the Cutting Edge Temperatures Using Inverse Heat Conduction Technique M. R. Santos1, S. M. M Lima e Silva2, Guimarães, G.1, S.R. Carvalho1 1Federal University of Uberlândia, FEMEC‐UFU, Uberlândia, MG, Brazil 2Federal University of Itajubá, IEM‐UNIFEI, Itajubá, MG, Brazil During the machining process, a considerable amount of the machining energy is transformed into heat due to plastic deformation of the workpiece surface, the friction of the chip on the tool face and the friction between the tool and the workpiece. High temperatures are generated in the region of the tool cutting edge, and these temperatures have a very important influence on the rate of wear of the cutting tool and on the friction between the chip and the tool and mainly on the tool life. The experiments of Tosun and Ozler [1] shown that the tool life increases significantly when the manganese steel specimens are heated during machining. They concluded that 400 0C is the optimum heating temperature considering the microstructure of the workpiece studied. That work demonstrates the great importance of the temperature distribution at the interface in various machining conditions. This paper makes an experimental and numerical investigation of different factors which influence the temperature distribution at the high speed steel (AISI M32 C) tool rake face during machining of a (ABNT 12L14) steel workpiece. The temperature distribution was predicted using finite volume elements with an inverse
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problem procedure. The inverse technique uses numerical and experimental results for both heat flux and temperature estimation. Temperatures were measured by thermocouples at positions distant from the region of interest. Heat fluxes at the tool – workpiece interface are estimated using these remotely measured temperatures. Experiments were performed to study the effect of cutting parameters on the cutting edge temperature. [1] N. Tosun and L. Ozler, Journal of Materials Processing Technology, 124, 99 (2002) ………………
DSL280 Mr. Arash Jafari Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia
Optimization of a CircularMicrochannel Heat Sink Using Entropy Generation Minimization Method A. Jafari1, Associated Prof. Dr. N. Mohd‐Ghazali2 1Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia New advances in micro and nano scales are being realized and the contributions of micro and nano heat dissipation devices are of high importance in this novel technology development. Past studies showed that microchannel design depends on its thermal resistance and pressure drop. However, entropy generation minimization (EGM) as a new optimization theory stated that the rate of entropy generation should be also optimized. Application of EGM in microchannel heat sink design is reviewed and discussed. Using EGM, majority of the published investigations are conducted based on rectangular cross section microchannel. Latest principles for deriving the entropy generation correlations are discussed to present how this approach can be achieved. The present study involves an optimization procedure using EGM method and derives the entropy generation rate in ncircular microchannel heat sink based upon thermal resistance and pressure drop simultaneously. The equations are solved using MATLAB and the obtained results are compared to the past studies. The effect of channel diameter and number of channels on the entropy generation rate, Reynolds number, thermal resistance and pressure drop is investigated. Analytical correlations are utilized for heat transfer and friction coefficients. [1] A. Bejan, Journal of Applied Physics. Vol.79, pp 1191‐1218 (1996). [2] C. Y. Yang, and T. Y. Lin, Experimental Thermal and Fluid Science, Vol. 32, pp 432–439 (2007). [3] J. Li, and G. P. Peterson, IEEE Transactions, Vol.29, Issue 1, pp145 – 154 (2006). [4] P. S. Lee, and S. V. Garimella, International Journal of Heat and Mass Transfer, Vol. 49, pp 3060–3067 (2006). [5] W. A. Khan, M. M. Yovanovich, and J. R. Culham, Semiconductor Thermal Measurement and Management Symposium, pp 78‐86 (2006). [6] A. Bejan, Convection Heat Transfer, third edition, pp. 1–119, (Wiley, New York, 2004) ……………… DSL300 Prof. Assunta Andreozzi DETEC, Università degli Studi Federico II, Piazzale Tecchio 80, 80125 Napoli, Italy
Analytical Solution for Quasi‐Steady State Two‐Dimensional Temperature Distribution in a Finite Depth Solid with a Moving Heat Source A. Andreozzi1, B. Buonomo2, O. Manca2 1DETEC, Università degli Studi Federico II, Piazzale Tecchio 80, 80125 Napoli, Italy 2DIAM, Seconda Università degli Studi di Napoli, Via Roma 29, 81031 Aversa, Italy
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Moving heat sources are frequently used in many manufacturing processes, including welding, cutting, heat treatment of metal and of electronic components. This is due to their ability to concentrate high powers over small localized areas. In particular, many studies have been carried out to predict temperature fields in such processes. Even if numerical methods are powerful tools to solve the thermal models describing the processing solid, especially when dealing with complex geometries, non‐linear boundary conditions and temperature dependent thermal properties, analytical approaches are still very useful. This is due to the need to provide (a) good insight into the significance of parameters affecting the process and (b) analytical solutions for validation of numerical codes. In order to predict the behavior of the material after the manufacturing process and to simplify the physical model, it is important to evaluate the most affecting parameters involved in the particular process in such a way as to optimize the material processing. The Peclet number, which compares the thermal diffusion term in the direction of the motion to the convective component, is the main nondimensional parameter governing the heat transfer mechanism in the system. In this paper an analytical solution of a two‐dimensional quasi‐steady‐state thermal conductive model in a solid with finite depth and infinite length under a moving heat source is evaluated. The spot is indefinite along the direction normal to the motion and the distribution along the moving direction is a linear combination of a gaussian and donut function. The evaluation of the solution is obtained by means of the Green function method. Results for each Peclet number are given. Temperature profiles along the moving direction and the depth and temperature fields are presented. ……………… DSL343 Mr. WILLY BASTIN Department of Mechanical Engineering, National Institute of Technology, Calicut
Convective Heat Transfer Studies of a Cylindrical Heater using Digital Interferometry Willy Bastin1 * and V. Sajith1 1Department of Mechanical Engineering, National Institute of Technology, Calicut *e‐mail:
[email protected] The free convection studies from cylindrical surfaces such as thin wires, tubes to the surrounding medium has got tremendous application in engineering field as corresponding heat transfer coefficients are essentially required for the design of heat transfer equipments. Steady state as well as the transient heat transfer studies essentially requires the temperature distribution in the medium surrounding the heat dissipating surface. The traditional method of temperature measurement is using the thermocouple probe, and for obtaining the temperature distribution in the medium either a number of probes or a moving probe technique is required. Both of these methods disturb the flow field and bring errors in the measurement. Hence a measurement technique which does not affect the flow field is always preferable in such situations. Optical methods can be effectively used, due to their non‐intrusive nature, good sensitivity and measurement accuracy. Measurement methods such as interferometry are extremely useful tools for visualizing the real‐time temperature distributions over the whole field through instantaneous photographs as well as in following transient phenomena through continuous recording of visualization patterns. The present investigation is aimed at developing an interferometric method for convective heat transfer measurement in air surrounding a cylindrical heater surface. The test specimen used here is a cylindrical heater of 2 cm diameter and 3 cm length. Heater coil is kept inside a steel tube and is supplied with stabilized AC through an autotransformer for controlling the heat output. A Mach‐Zehnder interferometric arrangement has been used in this work, to obtain the temperature distributions in air surrounding the heater surface. Interferometric methods utilize the interference of two coherent light beams for measurement of temperature distributions and heat transfer in an analysis domain, and depend on the additional phase lag introduced when these light beams pass through regions of different densities and refractive indices caused by the temperature field. The fringe patterns are grabbed using an AVT Marlin CCD camera, and the AVT Fire package software. The MZI set up has been validated using a vertical heater plate and the experimental results are compared with the theoretical results. The optical components are arranged in such a way to obtain parallel wedge fringes initially. Digital image processing technique has been used for analyzing the fringe patterns. The moiré fringes, ie isotherms around the cylindrical heater plate are obtained by the digital subtraction of the initial parallel fringes from the deformed fringes, which contains the information of the temperature distribution. The temperature corresponding to the isotherms are obtained by interferometric relations, knowing the reference temperature, measured using T type thermocouple. The temperature gradient, local heat transfer coefficient as well as heat flux at various location along the circumference of the cylindrical heater are obtained from the temperature distribution in the radial direction. The variation
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of the heat transfer coefficient along the circumference of the cylindrical heater surface at various angles has been plotted. Digital interferometry has been effectively utilized to study the steady state as well as transient heat transfer characteristics around the cylindrical heater. REFERENCES [1] J.V Herraez, R Belda, A study of free convection in air around horizontal cylinders of different diameters based on holographic interferometry. Temperature field equations and heat transfer coefficients. International journal ofthermal sciences(2002)A pp 261‐267 [2] T. Yousefi , M. Ashjaee , Experimental study of natural convection heat transfer from vertical array of isothermal horizontal elliptic cylinders, Experimental Thermal and Fluid Science 32 (2007) pp:614‐623 [3] R. Ghazy, B. El‐Baradie, A. El‐Shaer, F. El‐Mekawey, Measurements of the refractive indices and refractive index increment of a synthetic PMMA solutions at 488 nm. Optics & Laser Technology, 31 (1999) [4] Zhi‐Cheng Jian, Cheng‐Chih Hsu, Der‐Chin SuI,), Improved technique for measuring refractive index and thickness of a transparent plate. Optics Communications, 226 (2003), pp:35‐140 [5] Naylor,D.,2003,Recent developments in the measurement of convective heat transfer rates by laser interferometry, Int.J.of Heat and Fluid Flow, 24, pp:.345‐355 [6] M.Ashjaee, A.H.Eshtiaghi, M.Yaghoubi and T.Yousefi, Experimental investigation on free convection from a horizontal cylinder beneath an adiabatic ceiling, Experimental Thermal and Fluid Science, 32 (2007), pp:614‐623 ……………… DSL369 Dr. Elena Campagnoli Politecnico di Torino, Dipartimento di Energetica, C.so Duca degli Abruzzi 24, 10129 Torino
Thermal diffusivity of traditional and innovative sheet steels E. Campagnoli1, P. Matteis2, G. Scavino2 1Politecnico di Torino, Dipartimento di Energetica, C.so Duca degli Abruzzi 24, 10129 Torino 1Politecnico di Torino, Dipartimento di Scienza dei Materiali e Ingegneria Chimica, C.so Duca degli Abruzzi 24, 10129 Torino During the last years, in the automotive field the low carbon steels, used for the production of the car bodies by deep drawing, are gradually substituted by more advanced high strength steels in order to reduce vehicle weight. Independent of the used steel, the drawn car body components are joined together through a welding process and it is well known that the welded points undergo a reduction of the local tensile strength value. In developing an accurate welding process model, able to indicate which are the optimized process parameters and able to predict the final local microstructure, a significant improvement can be given by the knowledge of the welded steels thermal diffusivity at different temperatures. The laser‐flash method has been used in order to measure the thermal diffusivity of two traditional deep drawing steels, two high strength steels already in common usage, i.e. a Dual Phase (DP) steel and a TRansformation Induced Plasticity (TRIP) steel, and one experimental high‐Mn austenitic TWIP (Twinning Induced Plasticity) steel. The results show that the low carbon steels, at low temperatures, have a thermal diffusivity that is 4‐5 times larger then the TWIP steel. Their thermal diffusivity decreases by increasing temperature while the TWIP steel shows an opposite behaviour, albeit with a lesser slope, so that above 700 °C the TWIP thermal diffusivity results to be larger. The different behaviour of the TWIP steel in respect to the traditional ferritic deep drawing steels arises from its austenitic structure. Moreover, the DP and TRIP steels show intermediate values, their diffusivity being lower than that of the traditional deep drawing steels; this latter fact probably arises from their higher alloy content and more complex microstructure. ……………… DSL396 Mr. T. Anitha Mani Department of Chemical Engineering, Anna University, Chennai, Tamil Nadu, India
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EFFECTIVE HEAT TRANSFER IN CRUDE OIL REFINERY HEAT EXCHANGER BY RETRO FIT DESIGN T.Anitha Mani1, N.Gayathri1, N.Janani1 Under the Guidance of Dr.N.Nagendra Gandhi1 1Department of Chemical Engineering, Anna University, Chennai, Tamil Nadu, India Fouling refers to the accumulation of undesirable products on the surface of heat exchanger offering resistance to heat transfer. Reduced heat recovery and increased pressure drop are the two major aspects of fouling on a preheat train operation. The development of thermal and pressure drop models for crude oil fouling has enabled to perform analysis and to compare various design options. The use of fouling factors in heat exchanger design and lack of appreciation of fouling in traditional pinch approach has resulted in badly designed crude preheat networks that are expensive to maintain. Fouling model is applied at two levels 1. Assessment of adding extra area to individual exchanger 2. Design of a complete network using modified temperature field plot. Application to a refinery case study showed that both at the exchanger and network levels designing for maximum heat recovery using traditional pinch approach results in least efficient heat recovery over a time period when fouling occurs. REFERENCES: [1] Atkins, G.T., 1962, What to do about high coking rates, Petro/Chem Engineer, Vol. 34, pp 20‐25. [2] Kern, D.Q., 1988, Process Heat Transfer, McGraw‐Hill,NKnudsen, J.G., Lin, D. and Ebert, W.A., 1997, The determination of the threshold fouling curve for a crude oil, in: [3] Wilson, D.I. and Polley, G.T. (2001) “Mitigation of refinery preheat train fouling by nested optimisation”, Advances in Refinery Fouling Mitigation Session #46, AIChE, Houston, pp 287‐294. ……………… DSL415 Mrs. Y. Allouche UTTPI, Ecole Nationale d’Ingénieurs de Monastir, Route de Ouardanine, 5000, Monastir, Tunisia
A CFD Simulation of Thermal Performance of a Flat Plate Solar Energy Collector Case study for Tunis, Tunisia Y.Allouche1*, H. Mhiri1, G. Le Palec2, P. Bournot2 1 UTTPI, Ecole Nationale d’Ingénieurs de Monastir, Route de Ouardanine, 5000, Monastir, Tunisia 2 IUSTI, UMR CNRS 6595, 5 rue Enrico Fermi, Technopole de Chateau‐Gombert, 13013 Marseille Cedex 20, France. *
[email protected] A flat plate solar energy collector with water flow is simulated and analyzed using the computational fluid dynamic (CFD) software fluent V.6.2. As a first step, only the flat plate solar collector was treated without its storage tank: the CFD modeling of solar irradiation, the convection and radiation heat transfer mechanisms between the tube surface, glass cover and side walls were studied for two types of absorber surfaces: black body surface and selective one. For each type of absorber surface, the hourly variation of temperature rise fluid and absorber temperature during two typical summer and winter days was simulated for the model located in Tunis City (Tunisia). The weather conditions (instantaneous thermal heat flux and temperature) were taken in account in our study. The results show that the selective surface is more promising than black body one: a higher temperature of water outlet is observed in case of selective surface. As a second step the storage tank had been added to the flat plate solar collector which is equipped with a selective absorber surface, the thermal performance of a solar water heater without internal exchanger using a thermo siphon system is modeled. ……………… DSL447
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Dr. Pablo Muñoz UDESC ‐ Santa Catarina State University, Joinville, SC, Brazil
Optimization of a Unit Periodic Cell in Lattice Block Materials Designed for Thermo‐ mechanical Applications T.A. Carniel1, P.A. Muñoz‐Rojas1, E.C.N. Silva2 , A. Öchsner3 1UDESC ‐ Santa Catarina State University, Joinville, SC, Brazil 2USP – University of São Paulo, São Paulo, SP, Brazil 2University of Malaysia Lattice block materials are cellular materials made up of truss‐like periodic cells. They are characterized by their low weight, high stiffness and good heat dissipation properties. As opposed to other porous materials such as metal foams, lattice block materials have the attractive characteristic of regularity in their properties, since the pores follow a periodic pattern. These aspects, among others, have motivated intense research about the macroscopic behavior and applications of these materials. In this work, a layout optimization procedure is presented for designing the unit cell of a periodic lattice block material intended for thermo‐mechanical applications. Firstly, the formulation for calculating homogenized mechanical and thermal properties of 2D and 3D cells made of truss‐like elements is presented and validated. Next, a layout optimization problem is set which aims to maximize mechanical, thermal and thermo‐mechanical response of homogenized properties of truss‐like cells, in which both nodal coordinates and cross sectional areas are taken as design variables. The analytical sensitivity expressions are developed and given in detail, and the optimization is carried out using sequential linear programming (SLP). Results obtained considering 2D and 3D cases are presented to illustrate the methodology. ……………… DSL514 Mr. Roger Kempers Department of Mechanical & Manufacturing Engineering, Trinity College Dublin, Dublin 2, Ireland
Characterization of Thermal Contact Resistance in Metal Micro‐Textured Thermal Interface Materials using Electrical Contact Resistance Measurements R. Kempers1,2*, A. Lyons2,3 & A.J. Robinson1 1Department of Mechanical & Manufacturing Engineering, Trinity College Dublin, Dublin 2, Ireland 2Alcatel‐Lucent, Bell Laboratories Ireland, Blanchardstown, Dublin 15, Ireland 3Current Address: City University of New York, College of Staten Island, New York, USA *Corresponding Author Email: kempers@alcatel‐lucent.com Typical thermal interface materials (TIMs) consist of high thermal conductivity solid particles dispersed in a continuous, low‐ thermal conductivity organic compound. Despite using filler materials of very high thermal conductivity, the effective thermal conductivity of these TIMs is often two orders of magnitude lower than the pure filler materials. In addition, dispensing and flow of the particle‐matrix composite results in voids being trapped within the bond. To address these issues, a novel metal micro textured thermal interface material (MMT‐TIM) has been developed. This material consists of a thin metal foil with raised micro‐scale features that plastically deform under an applied pressure thereby creating a continuous, thermally conductive, path between the mating surfaces. Numerical tools have been developed that couple the mechanical and thermal properties and behaviour of MMT‐TIMs as they undergo large‐plastic deformation during assembly, however the thermal contact resistance remains an empirically fit parameter. Initial results have demonstrated a strong correlation between pressure and effective thermal conductivity exists for these TIMs indicating the contact thermal resistances contribute significantly to the measured thermal resistance and effective thermal conductivity of the MMT‐TIMs [1]. From an experimental standpoint, it is difficult to distinguish between the thermal contact resistance and bulk thermal resistance of the MMT‐TIM. Typically, for conventional TIMs, the contact resistance can be obtained experimentally by measuring several thicknesses of TIM, plotting the thermal resistance as a function of thickness and extrapolating contact resistance as the y‐
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intercept where the thickness is zero [2]. For MMT‐TIMs however, this method cannot be used due to the non‐uniform behaviour of the bulk TIM. The thermal contact resistance and electrical contact resistance are qualitatively similar as both of these phenomena depend on the ratio of actual, intimate contact area to the apparent contact area. However, from an electrical standpoint, the resistance of the mating surfaces and bulk MMT‐TIM are extremely small compared to the contact resistance at their interface. ……………… VIP‐DSL068 Prof. Dr. Sergio Nardini Seconda Universita' degli Studi di Napoli, Italy
Effect of Solid Thickness on Transient Heat Conduction in Work pieces Irradiated by a Moving Heat Source N. Bianco1, O. Manca2, S. Nardini2 and S. Tamburrino2 1DETEC, Università degli Studi Federico II, Piazzale Tecchio 80, 80125 Napoli, Italy 2DIAM, Seconda Università degli Studi di Napoli, Via Roma 29, 81031 Aversa, Italy Moving and stationary heat sources are frequently employed in many manufacturing processes and contact surfaces. In recent years applications of localized heat sources have been related to the development of laser and electron beams in material processing, such as welding, cutting, heat treatment of metals and manufacturing of electronic components. Analytical and numerical models for the prediction of the thermal fields induced by the stationary or moving heat sources in absorbing or non‐absorbing solids are useful tools for studying the afore mentioned problems. The analysis of thermal conductive distributions is important in order to broaden their field of application and to improve their control. Typical parameters involved in the processes for any particular application should be evaluated, in order to optimize the material processing and forecast the behavior of the solid. In this paper a three dimensional conductive field are analyzed and solved by means of the COMSOL Multiphysics code. The investigated work‐pieces are made up of a simple brick‐type solid. A laser source with combined donut‐Gaussian distributions is considered moving with a constant velocity along motion direction. The solid dimension along the motion direction is assumed to be infinite or semi‐infinite, while finite width (2ly) and thickness (s) are considered. Thermal properties are considered temperature dependent and the materials are considered isotropic. Surface heat losses toward the ambient are take into account. Results in terms of temperature profiles and thermal fields are given for some Peclet and Biot number values in order to evaluate the effect of solid thickness. ……………… DSL036 Prof. Alexei Essiptchouk Technological Institute of Aeronautics, Department of Physics Plasma and Processes Laboratory 12228‐900, ITA – CTA, São José dos Campos, SP, Brazil
Empirical Expression for Estimation of Thermal Characteristics of Material Used for Thermal Protection A M Essiptchouk1,2, L I Charakhovski1,2, W. Silva1, G P Filho1, H S Maciel1 1Technological Institute of Aeronautics, Department of Physics – Plasma and Processes Laboratory 12228‐900, ITA – CTA, São José dos Campos, SP, Brazil 2Luikov Heat‐ and Mass Transfer Institute (HMTI), National Academy of Sciences of Belarus, 220072, Minsk, Rep. Belarus Successful utilization of material in spacecraft thermal protection systems depends on its properties at high temperatures and on the material behavior under action of external high‐energy heat sources. Thermo‐physical properties define the rate dT/dτ and the depth δ of heat penetration and, accordingly, the necessary thickness of heat insulator. A simple relationship is usually applied for evaluation of δ in function of time. Here coefficient K depends on the heating rate of the material surface
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subjected to heat flux [1]. An expression for K can be obtained theoretically only for simple cases of uniform boundary conditions. The typical mode of heating of the sample front surface during firing test of thermal protection material can usually be approximated by considering two regions: Tf=cτ (linear growing up to time τ1) and Tf=const (permanent front surface temperature in the process of material degradation during the time interval τ2‐τ1). Each regime is characterized by corresponding coefficients K1 and K2, respectively. The temperature distribution inside the sample under the second regime is obtained by a linear superposition of solutions of Fourier equation for these regimes [2]. It can be expected, therefore, that a contribution of each thermal region to total coefficient K12 is a linear combination of K1 and K2. Comparison of results using this formula with accurate numerical calculations shows high accuracy of such modeling. Therefore this simplified formula can be recommended for application in engineering practice for estimating thermal diffusivity of material during test‐firing of heat shielding materials. [1] Ju.V. Polezhaev and A.A. Shishkov, Gas‐dynamic testing of heat shield, Promedek, Moscow, 248 (1992) [2] H.S. Carslaw and J.C. Jaeger, Conduction of Heat in Solids, Oxford Univ. Press, London and New York, 488 (1959) ……………… DSL379 Mrs. Amina Radhouane Unit of Heat and Thermodynamics of the Industrial Processes, National Engineering School of Monastir, Route of Ouardanine, 5000 Monastir, Tunisia
Dispersion of Twin Inclined Fume Jets of Variable Temperature Within a Crossflow A. Radhouane1, N. Mahjoub Said1, H. Mhiri1, G. Le Palec2, P. Bournot2 1 Unit of Heat and Thermodynamics of the Industrial Processes, National Engineering School of Monastir, Route of Ouardanine, 500 Monastir, Tunisia 2 IUSTI, UMR 6595, Technopôle Château‐Gombert, 5 rue Enrico Fermi 13013 Marseille, Cedex 20, France The “Jets in crossflow” configuration has been extensively handled in the literature due to its wide applicability in several fields. It is found in the aerodynamic applications like the chimney stack exhaust, V/STOL aircrafts, etc…in the industrial applications like the film cooling on turbine blades, the dilution holes in gas turbine combustors, fuel injection within combustion and/or chemical chambers, etc… Researches were rather dedicated to single and multiple jet configurations. The intermediate twin jet configuration was sensibly less explored in spite of its great interest. That’s why we propose to explore in the present work. We will particularly focus on the impact of the gradient between the jets and the crossflow temperatures on the resulting flowfield and more particularly on the dispersion of the fume contained within the jet nozzles. Being a transition between two common configurations makes the present one very interesting as its understanding is likely to highlight the consequences of introducing a second jet in the whole mixing process and to give an overview of the multiple jet case that will simply be a generalization of this case. The modelling of the present twin jet configuration will be based upon the resolution of the Navier stokes conservation equations by means of the finite volume method and the RSM (Reynolds Stress Model) second order turbulent model. A non uniform grid system particularly refined near the jet nozzles is adopted in order to detail the near field that shields the most interesting phenomena: the jets’ evolving, their mutual mixing, their mixing with the environing crossflow, the cooling/heating process, etc… The validity of the elaborated model was based upon PIV (Particle Image Velocimetry) experiments that were already carried out on the same configuration. Once validated, the model was generalized by introducing a non reactive fume within the jet nozzles and imposing a variable gradient between the interacting flows’ temperatures. The impact of the latter was particularly evaluated on the dispersion of the handled fume due to the relevance of the phenomenon and its close relationship to the pollution problem both in air and water media. ……………… DSL455 Dr. A. Benbrik
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University of Boumerdes, Faculty of Hydrocarbons 35000, Boumerdes, Algeria
Water Curtain Dimensioning for the protection of Hydrocarbon Storage Tank Against Thermal Radiation 1M. Cherifi, 1A. Benbrik, 2D. Lemonnier 1University of Boumerdes, Faculty of Hydrocarbons 35000, Boumerdes, Algeria 2Laboratoire d’Etudes Thermiques, ENSMA, Futuroscope, France In the early years of the oil and gas industry, fire in storage tanks was the common root of most of the incidents. One technique to protect the integrity of neighboring tanks is the water spray curtain, which can provide thermal shielding against fire. This study presents a numerical simulation of radiative heat transfer by the Mont Carlo method through a semitransparent medium (water spray curtain) containing water droplets and gas for the design of an effective thermal shielding system to protect LNG (or combustibles) storage tank against fire. This model will allow us to calculate exactly the attenuation factor of the water curtain as a function of its thickness, density and the size of water droplets. The medium is considered as a non grey, absorbing and anisotropically scattering. The spectral behavior of the medium is taken into account by the Mie theory [1] and the SNB model [2] applied respectively to water droplets and gas (H2O, CO and CO2). The calculated results are satisfactorily in agreement with the experimental data [3]. An application of these results to a real case of LNG storage tank was made and obtained a specifically characteristics of the curtain (thickness, density and the droplets size) for the maximum radiative heat flux. An attenuation factor up to 90% can be expected. [1] C.F. Bohren, D.R. Huffman, Absorption and Scattering of Light by Small Particles, (New York, Wiley, 1983). [2] A. Soufiani and J. Taine, High Temperature Gas Radiative Property Parameters of Statistical Narrow‐Band Model for H2O, CO2 and CO, and Correlated‐K Model for H2O and CO2, Technical note in Int. J. of Heat and Mass Transfer, 40, 987–991 (1997). [3] S. Dembélé, Modélisation et Etude Expérimentale des Transferts de Chaleur par Rayonnement dans un Rideau d’Eau Diphasique. Application à la Protection Incendie d’Installations Industrielles à Risques. Thèse de Doctorat, Institut National des Sciences Appliquées de Lyon, France (1998). ……………… DSL467 Dr. Ho‐Saeng Lee College of Engineering, Pukyong National University, Pusan 608‐739, Korea
Analysis of Cryogenic Refrigeration Cycle using Two Stage Intercooler H. S. Lee1, S. T. Oh2, H. W. Kim2, J. I. Yoon1, K. B. Lee1, S. G. Lee3 1 College of Engineering, Pukyong National University, Pusan 608‐739, Korea 2 Graduate School, Dept. of Refrigeration & Air‐conditioning Engineering, Pukyong National University, Pusan 608‐739, Korea 3KOGAS, Dongchun‐Dong, Yeonsu‐Gu, Incheon, 406‐130, Korea Natural gas is being preferred as the environmental‐friendly energy which has colorless, odorless and non‐toxic characteristics. Furthermore consumption rate of natural gas is increasing according to increment of international oil prices. Natural gas transportation systems are divided into PNG (Pipeline Natural Gas) system and LNG (Liquefied Natural Gas) system. LNG system has an advantage which is easier to transfer with handling smaller volume about 1/600 than PNG system. Therefore, natural gas liquefaction industry has been in the spotlight recently as the higher value industry. Energy efficiency is important to LNG production as feed gas is consumed in order to carryout theliq uefaction process. In this paper, two different types of natural gas liquefaction cycle with staged compression were designed and simulated for development of liquefaction process which is the core technology in the industry of natural gas liquefaction plant. These include a cascade cycle with two‐stage intercooler which is consisted of Propane, Ethylene and Methane cycle. Also, these cycles compared with modified staged compression process. The key parameters of the above cascade cycles were compared and analyzed.
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The COP (Coefficient of Performance) of cascade cycle with two‐stage intercooler and modified staged compression process showed about 12% and 23% high than that of basic cycle, respectively. Also, the yield efficiency of LNG improved comparing with the basic cycle by 28% lower specific power. [1] Jorgen Bauck Jensen et. al, Optimal oprtation of a mixed fluid cascade LNG plant, 9th International symposium on process systems engineering, 1569‐1574 (2006). [2] S.G. Lee et. al, The state of art of LNG Liquefaction Plant Technologies, The 3rd Korean Congress of Refrigeration, 65‐68 (2009). ……………… DSL518 Mr. Seung‐Moon Baek Department of Refrigeration and Air‐Conditioning Engineering, Pukyong National University, Busan 608‐739, Korea
Decrease Effect in Fouling on Plate Heat Exchanger Using Air Bubble Seung‐Moon Baek1, Won‐Sil Seol2, Ho‐Saeng Lee3 and Jung‐In Yoon3 1 Graduate School, Department of Refrigeration and Air‐Conditioning Engineering, Pukyong National University, Busan 608‐ 739, Korea 2 EME Co. Ltd., 556‐15 Eomgung‐dong, Sasang‐gu, Busan 617‐030, Korea 3 College of Engineering, Pukyong National University, Busan 608‐739, Korea The heat transfer performance of plate heat exchanger decreases as time goes by. The main reason for this phenomenon causes by the fouling on plate of heat exchanger. To remove the fouling, we have usually cleaned the plate of heat exchanger using chemicals or polishing by brush or cloth with hand after stopping the equipment and disassembling heat exchanger. But, to clean the plate using this method, the equipment needs to be stopped and disjointed heat exchanger. And we need to re‐joint after cleaning. Especially, the concern of environmental pollution happens in case of using chemicals. Therefore, we need to develop automatic fouling removal equipment which can keep high heat transfer efficiency continuously and solve the problem of environmental pollution. Until now, automatic fouling removal equipment has been developed and supplied using the method which cleans plate by sponge ball for multi‐pass shell & tube heat exchanger, but there is no equipment which can clean plate heat exchanger. So, in this paper, we developed and tested the equipment which can clean the fouling on plate heat exchanger automatically per constant period and interval using air bubble. The total heat transfer coefficient decreased with slower tendency on occasion of using air bubble than that of the existing method. Also, it was revealed that the variation of total heat transfer coefficient was affected by the size of air bubble and water velocity. Acknowledgments: This research was supported by EME Co. Ltd, and Small & Medium Business Administration of Korea government. [1] T.R. Bott., The Fouling of Heat Exchangers, Elsevier Science, New York (1995) [2] M.S. Abd‐Elhady, C.C.M. Rindt, and A.A. van Steenhoven, Optimization of Flow Direction to Minimize Particulate Fouling of Heat Exchangers. Proceedings of 7th International Conference on Heat Exchanger Fouling and Cleaning (Engineering Conferences International, Tomar, Portugal, July 1 ‐ 6, 2007) ……………… DSL524 Mrs. Mihwa Choi Engineering Center, Korean Electric Power Research Institute, Daejeon 305‐380, Korea
Formation, Structure and Influence of Hematite Scale Grown in Oxygenated Treatment Boilers on the Thermal Conductivity Mihwa Choi1, Seugran Yang1, Seungmin Lee1, Keesam Shin2, Junghwa Seo2
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1Engineering Center, Korean Electric Power Research Institute, Daejeon 305‐380, Korea. 2School of Nano and Advanced Materials, Changwon National University, Changwon, Korea. As time passes, corrosion scale forms and builds up on the inner most side the boiler tubes used in a fossil power plant. The main components of the corrosion products are iron oxide, magnetite and/or hematite, whose fraction and crystal structures depend on water treatment method. Since the introduction of the supercritical pressure boilers as large as 500MW in early 1990s, almost of the volatile treatment (AVT) has changed to oxygenated treatment (OT) which are applied in almost all the boilers. Upon the change of water treatment from AVT to OT, the scale of 13CrMo44 tube used in water system has changed to hematite from magnetite. Control of tube scale is very important in power plant since its build up often causes local overheating resulting in an explosive rupture or bad efficiency of heat conduction, causing abrupt failure with severe damage in maintenance. However, studies are rare on this topic up until now. In this study, crystal structure and thickness change of the scale in addition to the heat change in relation the water treatment method. The crystal structure and microstructure was analyzed using EBSD (Electron Back Scatter Diffraction). Image analyzer and laser flash method were used for thickness measurement and thermal conductivity measurement, respectively. The scales were formed of three different layers including mixture of magnetite and hematite, and the conductivity of the scale was lower when hematite is also present in addition to the magnetite. In case of steam tubes, same trend was observed. In addition, hematite was also formed in the inner most surface layer, which is yet to be clarified if it is caused by the change of the water system treatment. At any rate, it was clear that the heat conductivity is decreasing when hematite is present. Results on microstructural evolution and crystal structures will also be presented. Keyword: scale, hematite, thermal conductivity, scale thickness, X20CrMoV12.1, 13CrMo44 ……………… DSL224 Dr. Imen Gaied
New Photothermal Deflection method to determine thermal properties of bulk semiconductors Imen Gaied1, Salima Lassoued1, Fredéric Genty2 and Noureddine Yacoubi1 1Institut Préparatoire Aux Etudes d’Ingénieur de Nabeul IPEIN Merazka 8000 Nabeul‐Tunisie 2Groupe NANOMIR de l'Institut d'Electronique du Sud (IES, UMR UM2/CNRS n°5214) Université Montpellier 2 France In this paper, we present a new phothermal deflection technique (PTD) to determine thermal properties of bulk doped or undoped semiconductor such as GaAs, GaSb, InAs, etc…The method proposed here consist in covering the sample with a thin graphite layer in order to increase the photothermal signal and to avoid any reflection on the sample surface. This method deals with the analysis of the logarithm of amplitude and phase variation of the photothermal signal versus square root modulation frequency where the sample is placed in air and heated by a modulated light beam coming from a halogen lamp. So the best coincidence between experimental curves and corresponding theoretical ones gives simultaneously the best values of thermal conductivity and thermal diffusivity of the sample. The obtained values are in good agreement with those found in literature. The advantage of applying this method in this way lies in its simplicity and its sensibility to both thermal conductivity and thermal diffusivity. ……………… DSL299 Prof. Anthony Straatman
Modeling Thermal Dispersion in High‐Conductivity Porous Materials C.T. DeGroot1, A.G. Straatman1 1The University of Western Ontario, London, Ontario, N6A 3K7, Canada Transport in porous media has many applications in the sciences and engineering, including filtration, packed bed reactors, groundwater flows, and enhanced heat transfer. In heat transfer applications, modern graphitic foams have shown great potential due to their high effective thermal conductivity and large internal surface area. Analysis of flow and heat transfer in porous media is typically conducted using volume‐averaged equations for the macroscopic flow and thermal fields, rather
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than directly simulating the pore‐level flow. The process of volume‐averaging the energy equations, however, introduces new unknowns as it becomes necessary to decompose the velocity and temperature fields into the sum of their volume‐ average and a spatial deviation [1]. The spatial deviation terms are recast in terms of closure functions, which map the volume‐averaged fields onto the pore‐level deviations. As a result, the deviation terms may be recast as volume‐averaged terms with coefficients defined by the closure functions. The goal of the present work is to examine the details of the pore‐ level flow in high‐conductivity graphitic foams, in order to produce a closed, volume‐averaged model for flow and heat transfer in such materials. Due to the high‐conductivity of the medium considered here, local thermal non‐equilibrium between the fluid and solid phases is assumed to exist. The approach taken in this work is to solve for the flow and closure function fields in an idealized spherical‐void pore geometry [2] using a 3‐dimensional, unstructured, finite‐volume CFD code. Integration of the closure function fields provides results for the thermal dispersion conductivity and interfacial heat transfer, which are presented for a range of Reynolds and Prandtl numbers. In addition to providing a closed model for the study of flow and heat transfer in graphitic foams, results provide new insight into inertial effects on dispersion behaviour. [1] S. Whitaker, in Fluid Transport in Porous Media, Vol. 1, p. 1, J. Prieur du Plessis, Ed. (Springer‐Verlag, Southampton, UK, 1997). [2] Q. Yu, B.E. Thompson, and A.G. Straatman, ASME J. Heat Transfer, 128, 352(2006).
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Mass transport and related phenomena in metals and alloys
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Mr. Ladislav Celko Brno University of Technology, Faculty of Mechanical Engineering, Institute of Materials Science and Engineering, Brno, Technická 2, 616 69, Czech Republic
Diffusion in Al‐Ni and Al‐NiCr Interfaces at Moderated Temperatures L. Celko1, L. Klakurková1, J. Svejcar1 1Brno University of Technology, Faculty of Mechanical Engineering, Institute of Materials Science and Engineering, Brno, Technická 2, 616 69, Czech Republic. The diffusion couples for experimental study were prepared by HVOF spraying of nickel and nickel with 20 wt. % of chromium powders onto the aluminium sheet’s surface. The interfaces with sharp gradient of chemical concentration of these elements were prepared. Annealing at the temperatures 600°C and 630°C, close to the Al+Al3Ni eutectic melting point (639.9°C), with different dwell times were realized. The reactants during the annealing diffuse and create layers of Al3Ni2 and Al3Ni intermediate phase compositions. Moreover, nickel without assistance of chromium diffuses preferably by using grain boundaries into aluminium substrate and produces the strengthening of the substrate by stable Al3Ni and metastable Al9Ni2 particles. The microstructures were obtained by scanning electron microscope. Layer thickness measurements were realized by means of image analyses. Chemical composition was estimated by energy dispersive microanalysis measurements. According to the results of these analyses performed the average chemical interdiffusion coefficients and Wagner’s integral interdiffusion coefficients were calculated. DSL138 Dr. Carlo Massobrio Institut de Physique et de Chimie des Matériaux de Strasbourg, 23 Rue du Loess, BP 43, F‐67034 Strasbourg Cedex 2, France
Understanding Diffusion on Fcc(111) Transition Metal Surfaces: Exchange Diffusion and Mechanism of Preferential Nucleation C.Massobrio Institut de Physique et de Chimie des Matériaux de Strasbourg, 23 Rue du Loess, BP 43, F‐67034 Strasbourg Cedex 2, France Atomic‐scale simulation has largely contributed to gain insight into the diffusion properties of metallic species on transition metal substrates. Early experimental pieces of evidence on unconventional mechanisms (exchanges) occurring on relatively open surfaces (such as the (100) and the (110) ones) were substantiated by molecular dynamics results confirming that exchanges processes are a viable alternative to atomic hopping. However, on the modeling side, the simple analysis of the exchange mechanism on an unreconstructed fcc(111) substrate was found to be lacking. This was due to the prohibitively high barrier associated with this movement, this same high barrier being responsible for the predominance of hopping. Renewed interest for migration on fcc(111) surfaces has been stirred by the discovery of preferential nucleation on specific sites occurring on selected reconstructed surfaces, such as Au(111). The question arises on the atomic origin of this specific process and to its interplay with the diffusion scenario for the movement of atoms and clusters on compact surfaces. Very recently, we have applied large‐scale molecular dynamics to the understanding of two related issues related to morphology and dynamics of metallic species on fcc (111) substrates (1,2). As a first contribution (1), we have highlighted two different kinds of medium range diffusion via exchanges, medium range involving surface atoms next‐nearest neighbors of surface atoms. By considering Au(111) and Pt(111) substrates, we have shown that medium range diffusion can occur in a concerted movement of the ad‐atoms and two surface atoms or through a pair of two correlated short range exchanges.
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In a further investigation (2) carried out on a very large molecular dynamics system (47613 Au atoms on which Co atoms are deposited) we have proposed a new atomic mechanism for preferential nucleation on the herringbone reconstruction of Au(111). The origin of this mechanism is rooted into the topology of the potential energy surface for Co/Au(111) adsorption. The movement of Co atoms toward the most stable sites of the reconstructed surface has been followed in real time, providing a clear picture in which kinetics and energetics concur to the formation of Co islands at the kinks of the reconstruction, in line with experimental evidence. References: 1) H. Bulou and C.Massobrio, Mechanism of exchange diffusion on fcc(111) transition metals surfaces, Phys. Rev. B 72, 205427 (2005). 2) H. Bulou and C. Massobrio, New atomic mechanism of preferential nucleation on the herringbone reconstruction of Au(111), J. of Physical Chemistry, Letters 112, 8743 (2008). ……………… VIP‐DSL028 Prof. Dezső L. Beke Department of Solid State Physics, University of Debrecen, 4032Debrecen, P.O.Box 2., Hungary
On the Grain‐Boundary Diffusion in Polycrystalline Materials and Thin Films D.L. Beke1, J. Bernardini2 1Department of Solid State Physics, University of Debrecen, 4010 Debrecen, p.o.box.2. Hungray email:
[email protected] 2L2MP case 141, Faculté des Sciences St Jérôme, 13397 Marseille Cedex 20, France In this lecture we will give mainly an overview of our activity in research on grain boundary, GB, diffusion in different metallic substrates at Laboratories of Debrecen’s and Marseilles group. The lecture is dedicated in honour of professor Bokstein, since many of the result were obtained on the basis of stimulating discussions with him. The following problems (and still open questions related to them) will be addressed: i) Diffusion in a random network of grain boundaries with different structures and diffusion coefficients in polycrystalline materials ii) Studies of GB diffusion in thin films by surface analytical techniques iii) Grain boundary segregation and diffusion iv) Transition between B and C kinetic regimes of GB diffusion v) Diffusion along special grain boundaries in bi‐crystals. ……………… DSL090 Prof. Yuh Fukai Institute of Science and Engineering, Chuo University, Bunkyo‐ku, Tokyo 112‐8551 Japan
Hydrogen‐Induced Enhancement of Atomic Diffusion in Metals Y. Fukai Institute of Science and Engineering, Chuo University, Bunkyo‐ku, Tokyo 112‐8551 In 1993 we discovered that a large number of metal‐atom vacancies were formed in Ni and Pd placed under high hydrogen pressures and high temperatures. After subsequent extensive studies, it has come to be recognized that this phenomenon, called superabundant vacancy (SAV) formation, is a general feature of M‐H alloys, caused by reduction of the formation energy of a vacancy by trapping a multiple number of interstitial H atoms [1,2].
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One of the most important consequences of SAV formation is the enhancement of M‐atom diffusion. The diffusivity of M‐ atoms, given by D = xvDv, is increased because the vacancy concentration xv is increased dramatically whereas the vacancy diffusivity Dv is only modestly decreased by trapping H atoms. Enhancements by many orders of magnitude have been observed in the interdiffusion of Pd‐Rh [3], Cu‐Ni [4] and Au‐Fe [5] systems, and in the self‐diffusion in Nb [6, 7]. Recent measurements using nuclear resonant scattering of 57Fe have indicated that similar enhancements of diffusion take place when Fe samples are placed in contact with water at ~1GPa and 600~800°C. Some implications of the hydrogen‐induced diffusion enhancement for materials science will also be noted. [1] Y. Fukai, The Metal‐Hydrogen System, 2nd Ed. (Springer, Berlin, 2005). [2] Y. Fukai, H. Sugimoto, J. Phys.: Condens. Matter 19, 436201 (2007). [3] K. Watanabe, N. Ōkuma, Y. Fukai, Y. Sakamoto, Y. Hayashi, Scr. Mater. 34, 551 (1996). [4] E. Hayashi, Y. Kurokawa, Y. Fukai, Phys. Rev. Lett. 80, 5588 (1998). [5] Y. Yamazaki, Y. Iijima, M. Okada, Acta Mater. 52, 1247 (2004). [6] H. Koike, Y. Shizuku, A. Yazaki, Y. Fukai, J. Phys.: Condens. Matter 16, 1335 (2004). [7] T. Iida, Y. Yamazaki, T. Kobayashi, Y. Iijima, Y. Fukai, Acta Mater. 53, 3083 (2005). ……………… DSL424 Prof. Ulrich Krupp FH Osnabrück ‐ University of Applied Sciences Faculty of Engineering and Computer Science Albrechtstr. 30, 49076 Osnabrück Germany
The Significance of Mechanical Stresses during Internal Corrosion of Engineering Alloys U. Krupp1, R. Naraparaju2, H.‐J. Christ2 Faculty of Engineering and Computer Science, University of Applied Sciences Osnabrück, 49009 Osnabrück, Germany Institut für Werkstofftechnik, Universität Siegen, 57068 Siegen, Germany u.krupp@fh‐osnabrueck.de Internal corrosion often results in a premature breakdown of high‐temperature components, e.g. turbine blades in aircraft engines and land‐based gas turbine or heating elements in furnaces. This can be attributed to both an embrittlement of the surface layer and the consumption of strengthening elements connected with phase destabilization, e.g. g´ dissolution due to the precipitation of internal nitrides and oxides. Since the specific volume of these internal precipitates is much higher and the thermal expansion is much lower than it is the case for the metallic matrix internal stresses are formed during the internal oxidation and nitridation process giving rise to micro‐crack initiation and a reduction in the load‐carrying cross section of the respective component. Several Ni‐base alloys of the system Ni‐Cr‐Al‐Ti were exposed to high temperatures under various conditions at temperatures between 800°C and 1100°C: air, oxygen‐free nitrogen atmosphere, and thermal‐cycling. Corresponding to the extent of internal corrosion attack a surface coverage of base‐metal protrusions was observed. According to earlier studies these protrusions are believed to be a consequence of an outward diffusion flux driven by high compressive stresses in the internal precipitation zone. The occurrence of this effect was supported by thermal cycling, where repeated oxide‐scale spallation gave rise to massive internal corrosion accompanied by crack formation. The formation of internal stresses was proven by X‐ ray diffraction and electron microscopy and is believed to be due to dislocation pipe diffusion rather than the Nabarro‐ Herring mechanism. Mechanically tests of internally‐nitrided specimens and creep tests in oxygen‐free nitrogen atmosphere revealed a pronounced brittle behavior showing plenty of cracks exclusively within the internal precipitation zone and an increase in the internal corrosion zone due to creep loading. The experimental results are discussed taking a numerical treatment, of the diffusion and precipitation processes of the participated species by the self‐developed software tool INCORR into account. ……………… DSL282
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Mr. Eduardo Ribeiro Lagreca PEMM‐COPPE/UFRJ, P.O. Box 68505, 21941‐972 Rio de Janeiro, RJ, Brazil
Hydrogen Diffusivity and Solubility in Pd‐Nb Internally Oxidized Alloys Authors: E. R. Lagreca1, V. M. Azambuja2 and D. S. dos Santos1 1PEMM‐COPPE/UFRJ, P.O. Box 68505, 21941‐972 Rio de Janeiro, RJ, Brazil 2CEFET‐ES, Av. Vitoria, 1729 ‐ Jucutuquara ‐ Vitoria ‐ES. CEP: 29040‐780 Due to the high hydrogen solubility and diffusivity in their matrix, Pd and Pd‐based alloys are largely used as hydrogen filters and separators [1]. When internally oxidized, these alloys can have even higher hydrogen permeability, which is desirable for these applications. In this work, the hydrogen diffusivity and solubility in Pd‐Nb alloys were studied by using gas hydrogen permeation tests, in the conditions of solid solution and internally oxidized for 24h at 800°C and 1000°C. These tests were undertaken in the temperature range of 100‐600°C. Furthermore, temperature programmed desorption (TPD) technique, to analyze the hydrogen‐trap sites interactions, and X‐ray diffraction were performed. The hydrogen permeation results showed an expected lower diffusivity for the 800°C internally oxidized alloy, in comparison with the solid solution alloy, because of the presence of nanoparticles dispersed in the matrix, which act as effective trap sites for hydrogen diffusion. The hydrogen binding energy with different microstructure was determined by TPD technique. It was found that the most pronounced binding energy was observed for oxidized Pd‐Nb at 800°C for 24 h. [1] D. S. dos Santos, V. M. Azambuja, L. Pontonnier, S. Miraglia, D. Fruchart. Journal of Alloys and Compounds, Volumes 356‐357, 11 August 2003, Pages 236‐239 ……………… DSL293 Mrs. Karla Roberta Freitas da Silva PEMM‐COPPE/UFRJ, P.O. Box 68505, 21941‐972 Rio de Janeiro, RJ, Brazil
Hydrogen diffusivity and hydride formation in rich‐Zirconium alloys used in nuclear reactors K.R.F. Silva1, D.S. dos Santos1, A.F. Ribeiro1, L.H. Almeida1 1PEMM‐COPPE/UFRJ, P.O. Box 68505, 21941‐972 Rio de Janeiro, RJ, Brazil. Rich‐Zirconium alloys, or more frequently called Zircaloys, are used in nuclear technology as cladding materials due to their high corrosion resistance, low neutron absorption and good mechanical properties at high temperatures. During service, these alloys are submitted to high pressure (160 atm) and high temperature (600K). In these conditions, the tubes may suffer corrosion such as: Zr + 2H2O ZrO2 + 2H2, and the resulting hydrogen diffuses through the oxide layer and may be absorbed by the alloy. Hydrogen is known to adversely affect the mechanical properties of zirconium alloys. It has been reported [1] that the operational performance of Zircaloy tubes is largely restricted by problems associated with hydrogen absorption. Therefore, considerable work has been done to understand the interaction between hydrogen and the microstructure of the tubes. In this work, we present a study of the hydrogen diffusivity in two zirconium alloys used in the nuclear industry, named ZirloTM and M5TM by means of hydrogen permeation tests, thermal desorption spectrometry (TDS) and transmission electron microscopy (TEM) analysis. The microstructural analysis performed by TEM of the as‐received tubes revealed fine precipitates in the microstructure of the alloys. The TDS tests were performed after a hydriding treatment and the spectra showed peaks which are associated with two trap sites: the precipitates analyzed by TEM and the zirconium hydride. Therefore, it was possible to determine the hydrogen dissociation energy for each trap site. Finally, the hydrogen permeation tests allowed us to evaluate the role of the precipitates during hydrogen diffusion and calculate the hydrogen diffusivity in the a‐Zr matrix. [1] C.E. Coleman and D. Hardy, J. Less Common Met., 11, 168 (1966).
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……………… DSL062 Mrs. Beril Kaya Istanbul Technical University, Mechanical Engineering, 34437, Istanbul, Turkey
Ion Nitriding of CoCrMo Alloys B. Kaya, S. Yilmaz, C. Ergun Istanbul Technical University, Mechanical Engineering, 34437, Istanbul, TURKEY. Cobalt‐chromium based alloys have been in use for many decades as a biomedical material in dental and orthopedic applications (such as dental implants and restorations, bone and joint replacement, as well as heart valves, etc.) because of their excellent mechanical and corrosion properties [1‐3]. However, in vivo mechanical, chemical and biological properties of these alloys can be improved by surface modifications in order to meet the requirements demanded for a wide variety of clinical applications [4, 5]. In this study, medical grade cast CoCrMo alloy (F75) was ion nitrided under different process parameters including time (2, 4 and 9 hr) and temperature (600, 700, 8000C) at a gas mixture of 80%N2–20%H2 in order to accomplish these improvements. The nitride surfaces were characterized by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). Electron probe microanalysis (EPMA) measurements were used to study the cross sections and elemental distribution of diffusion layers after ion nitriding. The roughness analyses of the surfaces were performed using atomic force microscopy (AFM). MicroVickers hardness tests were done on the cross sections and the surface of the nitrided specimens to investigate the hardness profile. The significant effects of nitriding temperature and time on the microstructure and hardness value of nitride surface layers were displayed. [1] J. Black, G. Hastings, Handbook of Biomaterial Properties, p.167, Chapman&Hall, UK (1998). [2] J.R. Davis, Handbook of Materials for Medical Devices, p.31, ASM International, USA (2003). [3] J.B. Park, R.S. Lakes, Biomaterials an Introduction, p.83, Plenum Press, USA (1992). [4] R. Wei, T. Booker, C. Rincon, J. Arps, Surf. Coat. Technol., 186, 305 (2004). [5] O. Ozturk, U. Turkan, A.E. Eroglu, Surf. Coat. Technol., 200, 5687 (2006). ……………… DSL110 Mr. Vladimir Esin Moscow State Institute of Steel and Alloys, Moscow 119049, Russia
Models for the Porosity Growth and Dissolution in Single‐Crystal Nickel‐Base Super Alloys B.S. Bokstein1, V.A. Esin1, A.O. Rodin1, I.L. Svetlov2 1Moscow State Institute of Steel and Alloys, Moscow 119049, Russia 2All‐Russian Institute of Aviation Materials, Moscow 105005, Russia Blades of the hot stage of gas turbine aeroengines are manufactured from single‐crystal nickelbase superalloys [1]. However, a dangerous defect ‐ pores ‐ cannot be excluded completely. In spite of their small size, about a few ten of micrometers, they deteriorate the mechanical properties significantly, especially the fatigue lifetime [2]. The investigation of the methods of the porosity growth and dissolution is of high importance for improving the mechanical properties. In the present work an analytical model for the pores growth during homogenization was developed based on the Kirkendall‐ Frenkel effect: generation of vacancies due to imbalanced cross‐diffusion of the alloying elements. Numerical results obtained using the structural parameters of the alloy CMSX‐4 give a satisfactory agreement with the measured porosity. The degree of dendritic segregation of the alloying elements, their diffusion coefficients and the spacing of the dendrites determine the growth rate of the pores during homogenization. For the long periods of time the saturation of porosity was shown.
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A thermodynamic and kinetic model for the diffusion dissolution of pores during Hot Isostatic Pressure (HIP) [3, 4] was proposed. The determining role of the applied pressure for the pores with the radius more than 100 nm was shown. The dissolution time is proportional to the square of the initial pore radius and inverse pressure. The small pores (radius less than 100 nm) dissolve rapidly under the capillary forces. [1] R.E. Shalin, I.L. Svetlov, E.B. Kachanov et al. Single‐Crystals of Nickel‐Base Superalloys, Mashinostroenie, Moscow 1997. [2] K. Fullagar, R. Broomfield, M. Hulands et al. The 39th ASME/IGTI International Gas Turbine and Aero Engine Congress and Exposition, ASME, New York, pp. 1‐12, 1994. [3] Z.Q. Chen, N. Jones, D.M. Knowels. Acta Mater. 50, 1095 (2002). [4] S.S. Haurov. Technology of light alloys. 3, 43 (1985). ……………… DSL398 Dr. Faina Muktepavela Institute of Solid State Physics, University of Latvia, Riga LV1063, Latvia
The Role of Diffusion Accommodation and Phase Transformation in the Deformation Behaviour of the Interphase Boundaries in Ultrafine Grained Sn‐Pb Eutectic F.Muktepavela1, R.Zabels Institute of Solid State Physics University of Latvia, LV1063 Riga, LATVIA The mechanical properties of the interphase boundaries (IB) and phases in the Sn– 38wt.%Pb eutectic both in the deformed and annealed state were investigated at room temperature using tensile, micro‐ and nanoindentation tests. SEM, AFM and optical microscopy were used for the structural investigations. It has been shown that the deformation of the alloy occurs at the Pb/Sn IB in the form of the superplastic GBS. The softening of the Pb/Sn IB and the high plasticity of the deformed Sn–Pb eutectic during GBS are caused by the fast developing sintering (micropores closing) processes under the action of the capillary forces on the Pb/Sn IB. These diffusion accommodation processes are facilitated by the low values of the Pb/Sn interphase energy (0.07 J/m2) and kinetically allowed due to the relatively high homologous temperature (>0.5∙Tm) [1]. During plastic deformation the decrease of the grain size of the eutectic is accompanied by the lead diffusion along the grain boundaries of tin. Thus, the grain boundaries Sn/Sn vanish being substituted by the IB Pb/Sn. Such process of grain boundary phase transition due to the tin’s overlaying with lead is thermodynamically favourable because the condition γGB > 2 γIB is satisfied. From the results of micro‐ and nanohardness measurements it follows that both the Sn and Pb phase in the annealed eutectic are strengthened and the relaxation processes occur mainly at the IB. The IB in the annealed Sn–Pb eutectic act as barriers to the motion of dislocation ensemble when the size of the plastic zone is comparable to the grain size and lower the hardness values due to the development of GBS when more grains are involved in the process of deformation. The obtained values of the nanohardness and elastic modulus evidence that the IBs in the Sn–Pb eutectic have to be considered as a separate quasi‐phase with its own properties. [1] F.Muktepavela, N.Zaporina Defects and Diffusion Forum, 237‐240, 745 (2005) ……………… DSL095 Mr. Peter Varga Budapest Tech Polytechnical Institution Banki Donat Faculty of Mechanical and Safety Engineering, Department of Materials Science and Technology, Budapest, 1081, Hungary
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The Effect of Alloying Elements on the Stability of Centerline Segregation Mihaly Reger1, Balazs Vero2, Ibolya Kardos3, Peter Varga1 1Budapest Tech Polytechnical Institution Banki Donat Faculty of Mechanical and Safety Engineering, Department of Materials Science and Technology, Budapest, 1080, Hungary 2Bay Zoltan Foundation, Institute for Materials and Technology, Budapest, 1116, Hungary 3 ISD DUNAFERR Co., Innovation Management, Dunaujvaros, 3500, Hungary The paper deals with the stability of centerline inhomogenity of the continuously cast slabs. The centerline segregation is a disadvantageous failure of slabs which can affect the quality properties of the products. During the hot rolling of the slabs the centerline segregation pattern will become thin and stretch and it can detect also in the middle part of heavy plates and coils It is a common experience that the centerline segregation of heavy plates can not decrease easily by post heat treatment. The pattern of the centerline segregation was modeled physically by preparing a sandwich structure of steel plates with different levels of carbon and alloying elements. Homogenization experiments were performed and the samples were examined metallographically. Diffusional calculations proved the governing role of carbon activity which is influenced by the distribution of alloying elements. Keywords: centerline segregation, activity of carbon, effect of manganese, diffusional homogenization ……………… DSL239 Mrs. AnjaInes Pommrich Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft‐ und Raumfahrt (DLR), 51170 Köln, Germany
Self‐diffusion of transition metal X in Si90X10 melt A. I. Pommrich 1, A. Meyer1 , D. Holland‐Moritz1, T. Unruh2 1Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft‐ und Raumfahrt (DLR), 51170 Köln, Germany.2Forschungsneutronenquelle Heinz Maier‐Leibnitz, FRM‐II, Technische Universität München, 85747 Garching, Germany Crystal growth is limited by diffusion of mass in the melt. For an understanding of the underlying mechanisms of mass transport the knowledge of temperature and concentration dependence of the diffusion coefficients is a necessary prerequisite. However, diffusion experiments on liquid Silicon are challenging due to the high chemical reactivity of liquid Silicon and the high process temperatures involved. In addition in diffusion experiments, applying capillary methods, data are altered by buoyancy driven convection effects. We combine containerless processing via electromagnatic levitation with quasi‐elastic neutron scattering and measure self‐ diffusion coefficients [1]. We studied the self‐diffusion of Ni, Ti and Co in liquid silicon in a wide temperature range of several 100 K above and below the respective liquidus temperature. The results show that the self‐diffusion of Ni, Ti and Co in liquid Silicon is quite similar with values in the range of 10‐8 m2s‐1 . The diffusion of Ni in liquid Silicon is independent of alloy composition from 5 to 20 atm‐% Ni [2]. The Ni self‐diffusion in liquid Silicon is about a factor of 5 faster then in pure liquid Ni and governed by the mobility of the Si majority component. [1] A. Meyer, S. Stüber, D. Holland‐Moritz, O. Heinen and T. Unruh, Phys. Rev. B, 77, 092201 (2008). [2] A. I. Pommrich, A. Meyer, D. Holland‐Moritz and T. Unruh, Appl. Phys. Lett., 92, 241922 (2008). ……………… DSL470 Prof. Young‐Woon Kim Department of Materials Science and Engineering, Seoul National University, Gwanak‐gu Silimdong San 56‐1, Seoul 151‐744, Korea
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In‐situ observation of deformation twin in TWIP steel Sung‐Il Baik,* Tae‐Young Ahn,* Woong‐Pyo Hong,* Yeon‐Seung Jung,** Young‐Kook Lee,** and Young‐Woon Kim.* * Department of Materials Science and Engineering, Seoul National University, Gwanak‐gu Silimdong San 56‐1, Seoul 151‐744, Korea ** Department of Metallurgical Engineering, Yonsei University, Shinchon‐dong 134, Seodaemun‐gu, Seoul 120‐749, Korea Fe–Mn twinning‐induced plasticity (TWIP) steels have attracted research attention due to its high strength and exceptional plasticity in recent years [1]. These enhanced superior formability and strength satisfied the improved safety standards for high energy absorption in the construction and crash resistance in the automotive industry. In this Fe ‐ Mn TWIP steel, stacking fault energy (SFE) is the key parameter to determine the strengthening mechanism [2]. But stacking fault related microstructure changes were well studied but the formation mechanism of twin is not well understood. In this study, the generation of mechanical twin was observed by in‐situ tensile test in TEM and the effect of SFE was discussed linked with the measured SFE. Plan view TEM (PTEM) tensile samples were prepared by wire‐cutting method. Sample thinning was made by going through a typical sample preparation technique by grinding polishing, and followed by electrochemical thinning. Philips CM20 and JEOL 3000F were used to investigate the microstructural changes after in‐situ deformation. Sequential generation of dislocations movement, planar glide, stacking fault, twin at near [110] zone axis of TWIP steel were observed. True strain in tensile sample was marked in the bottom, which was measured by reference point marked before tensile strain. Dislocation movement in this TWIP steel starts at (111) planar slip plane and then split into partial dislocations to form stacking faults (SF). After the formation of the first operation of dislocations in the grain with low Schmid factor, dislocations from other slip planes were generated across the planar glide. Sequential SF generate twin along the crossed dislocation. Twin acts as a fracture source in the further strain along the (111) plane. Stacking fault and twin in TWIP steel are shown in high resolution image and selected area diffraction pattern at [110] zone axis. Darkfield image of (002) twin spot from SADP confirmed that there existed twin. In the initial stage, planar glide occurred and formed stacking faults with further strain, which was, in turn, believed to form twins. Movement of dislocation and twin generation were affected by the weight percent of Mn contents. Reduction of Mn contents decreased of stacking fault energy. And these lowering of SFE lead to non‐ sequential stacking fault and makes epsilon martensite. References [1] O. Grassel et. al., J. Appl. Phys., IV 5, (1997) 383. [2] B. X. Huang et. al., Meter. Sci. Eng. A 438‐440 (2006) 306. [3] This study was supported by a grant from the Fundamental R&D Program for Core Technology of Materials funded by the Ministry of Commerce, Industry and Energy, Republic of Korea. ……………… DSL326 Dr. Thomas Hummelshøj Technical University of Denmark, Department of Mechanical Engineering, Kemitorvet b. 204 DK‐2800 Kgs. Lyngby Denmark Systematic studies of metal dusting corrosion T. S. Hummelshøj1 T. Christiansen1 and M.A.J. Somers1 1Technical University of Denmark Department of Mechanical Engineering Kemitorvet b. 204 DK‐2800 Kgs. Lyngby Denmark Keywords: Metal dusting corrosion; stainless steel; expanded austenite; kinetics Fe‐based (steel) and Ni‐based high chromium alloys are widely applied as high temperature materials in the petrochemical industry. All Fe‐based and Ni‐based metals in high temperature processes that get in contact with carbon‐bearing gases like syngas in the temperature range 450C‐850C are subjected to carburization, i.e. dissolution of carbon in the alloy and the development of carbides. Generally, such carburization may lead to a very aggressive corrosion phenomenon known as metal
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dusting (MD) or catastrophic carburizing [1, 2]. The metal dusting corrosion manifests itself as a mixture of fine carbides, pure metal particles and carbon dust and can be in the form of pitting and general metal wastage. The wide range of incubation times, and consequently, specimen exposure times ranging from 350 hours to 4 years has greatly complicated, and has as yet, hindered a thorough investigation of the parameters influencing the kinetics of the catastrophic carburizing process. For which reason, very few systematic investigations of the mechanism and the kinetics can be found. Hitherto, the decomposition of carbon expanded austenite has not been associated with the metal dusting corrosion mechanism. Reported research has neither included the occurrence and subsequent decomposition of carbon expanded austenite, nor a description of the actual formation of carbides. Specifically the decomposition sequence in carbon expanded austenite has not been investigated. The process subsequent to the onset of MD is in general referred to as ‘carburization and carbide formation’. In order to be able to make reliable forecasts of the time to the onset of MD, it is necessary to include the development and decomposition of carbon expanded austenite. In this study, a fundamental different approach to the investigation of metal dusting is followed. A recently patented method [3] developed for surface hardening of stainless steels is applied to “bypass” the incubation time. With this method the Fe‐ based and Ni‐based alloys are attacked homogeneously in a strongly accelerated way, dramatically facilitating the investigations of the catastrophic carburizing process. [1] Grabke, H.J.; Materials and Corrosion, 49, no. 5, p. 303, (1998) [2] Szakálos, P.; Materials Science Forum, Vols. 522‐523, p. 571, (2006) [3] Christiansen, T, Somers, M.A.J.; Carburizing in hydrocarbon gas, PCT/DK2006/000363 ……………… DSL119 Dr. N. Bouzroura Laboratoire ‘’Solutions solides’’, Faculté de Physique, USTHB BP 32, El‐Alia, Bab‐ezzouar, Algiers, Algeria
Influence of Small Amount Addition of Cd, Sn and Ge on the Kinetic of Pre‐Precipitation Phase by Quenched Vacancies Diffusion of the Al‐Zn‐Mg and Cu‐Be Alloys Nour‐eddine BOUZROURA1,a,Mouhydine KADIHANIFI1,b 1Laboratoire ‘’Solutions solides’’, Faculté de Physique, USTHB BP 32, El‐Alia, Bab‐ezzouar, Algiers, Algeria Fax: 21321247344
[email protected],
[email protected] Keywords: GP zones, Al‐Zn‐Mg, Cu‐Be‐Cd, vacancies The influence of Cd and Ge on the kinetic of the GP zones formation has been studied for Al‐7%Zn3%Mg0.05%Cd(0.05%Sn) and Cu‐2%Be0.3%Cd(0.3%Ge). Their volumic fraction f(t) is determined by using microhardnesss method showing the influence of t time of ageing at 80 an 200 C respectively for Al‐Zn‐Mg‐Cd(Sn) and Cu‐Be‐Cd(Ge). The results obtained show that the addition of Cd and Sn atoms cause, respectively a delay in the GP formation of Al‐Zn‐Mg alloy and an acceleration of the kinetic of GP formation in Cu‐Be‐Cd. The interpretation of these results is based on the predominant interaction between Cd and Sn atoms with the high concentration quenched vacancies diffusion in these study copper alloys. ……………… VIP‐DSL024 Prof. Odila Florencio UFSCar, Brazil
Diffusion Phenomena of the Oxygen and Nitrogen in Niobium by Mechanical Spectroscopy O. Florêncio1, P.S. Silva Jr1, C.R. Grandini2 1Federal University of São Carlos, São Carlos, São Paulo, CEP13565‐905, BR.
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2São Paulo State University, Bauru, São Paulo, CEP17033‐360, BR. The short‐range diffusion phenomena (Snoek Effect) was investigated by mechanical spectroscopy measurements between 300K and 650K, in the polycrystalline niobium sample, containing oxygen and nitrogen, using a torsion pendulum operating in frequencies at the hertz bandwidth, with heating rate of 1K/min and pressure about 2x10‐5mbar. Experimental spectra of anelastic relaxation were obtained under three conditions: as received sample; annealed sample and subsequently annealed in an oxygen atmosphere for three hours at 1170K in partial pressure of 5x10‐5mbar. The experimental spectra obtained were decomposed by the successive subtraction method in elementary Debye peaks, the anelastic relaxation processes were identified, and the parameters were obtained. With these relaxation parameters obtained and the lattice parameters, the interstitial diffusion coefficients of the oxygen and nitrogen in niobium were calculated for each kind of preferential occupation (octahedral and tetrahedral). The results were compared with the literature data [1,2], and confirmed that the best adjustment is for the preferential occupation octahedral model for low concentrations of interstitial solutes, but at higher concentration of oxygen were observed deviations of experimental data for the interstitial diffusion coefficients of oxygen in niobium when compared with the literature data, this could be related to the possible occurrence of a double occupation of interstitial sites in niobium lattice by oxygen interstitial. [1] E. Fromm in Gase und Kohlenstoff in Metallen, (eds. E. Fromm and E. Gebhardt), Berlin Springer, (1976). [2] G. Hörz, et al., Gases and Carbon in Metals, Physics Data, (1980). ……………… DSL359 Mr. Tomáš Dvorák Institute of Materials and Machine Mechanics, SAS, Račianska 75, 831 02 Bratislava, Slovakia
Thermal Expansion of Advanced Materials for High Temperature Fusion Applications T. Dvorák Institute of Materials and Machine Mechanics, SAS, Račianska 75, 831 02 Bratislava, SK Tungsten (W) and copper (Cu) are materials suitable for production of metal matrix composites (MMC) that can be used in specific high temperature applications [1]. Tungsten has the highest melting point and also high resistance to erosion [2] and copper is a ductile and very high conductive material. And therefore copper / tungsten composites (Cu/W MMC) can be applied in some parts of fusion reactor structures where they need to withstand both high heat flux (20 MW/m2) and radiation damage. In the fusion reactor the MMC is planned to work in the high temperature environment (up to 600°C) for a longer time. In the paper two different technologies for preparation of the composite are presented: vacuum diffusion bonding and gas pressure infiltration. Samples contained different volume fractions of tungsten fibres (from 10% to 78%) that were arranged in unidirectional, cross‐ply and circular architecture. The coefficient of thermal expansion (CTE) of Cu/W MMC samples was measured in the longitudinal and transverse direction to the fibre orientation and it strongly depended on arrangement of reinforcing phase and direction of measurement. For unidirectional material it was 4 ‐ 6 ppm.K‐1 and 11‐12 ppm.K‐1 in directions parallel and transverse to the fibre orientation, respectively. Special samples in a shape of discs and tubes contained reinforcement that was wound around the sample centre (circumferential winding) or was cut‐out from the Cu/W MMC plate. In the second case the reinforced fibres had the cross‐ ply arrangement. The CTE of tubes and discs measured in radial direction showed values from 5 ppm/K to 20 ppm/K for composites containing 72 and 10 vol. % of W‐fibres, respectively (circumferential fibre orientation). Samples reinforced with the W‐mesh laid normally to the tube axis showed the CTE slightly smaller (4.5 – 7 ppm/K) (cross‐ply fibre orientation). [1] J. Koráb et al:.Abstracts books: International Conference Matrib (2008) [2] Y. Nemoto et al., J. of Nuclear Materials, Vol. 283‐287, 1144 (2000)
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……………… DSL020 Prof. Jaromir Drapala Department of Non‐ferrous Metals, Refining and Recycling Institute of Mining and Metallurgy ‐ Technical University of Ostrava Av. 17. listopadu 15 708 33 Ostrava ‐ Poruba CZECH REPUBLIC
The Study of Reactive Diffusion in the Presence of the Dissolution of Copper in the Melt of Solders P. Kubíček1, J. Drápala2 1Na Čtvrti 14, 700 30 Ostrava‐Hrabůvka, Czech Republic 2 Vysoká škola báňská – Technical University of Ostrava; Faculty of Metallurgy and Materials Engineering; 15, Av. 17. listopadu, 708 33 Ostrava – Poruba, Czech Republic In this work we give heed especially to the dominating process, which is the solid metal A dissolving in the melt B. During the dissolving the melt B saturates with the metal A and the process is influenced by convections which are characteristic for the given experimental configuration. A theoretical description of the kinetics of the solid phase dissolving in melt will be presented for the case of planar dissolving which can be realized e.g. in capillaries. Cylinders of the solid metal A are placed in capillaries and a column of the melt B is put above them. The aim is to derive a relation for the interface boundary c(t) movement in dependence on time and a time course of growth of the element A concentration in the melt B. There are problems with accurate determination of the interface boundary movement after certain heating times of specimens, when it is observed experimentally, since intermetallic phase create in the original A metal at both the diffusion and cooling and some phases segregate at the solidifying melt cooling. This results in inaccurate determination of the interface boundary at the end of experiment and thus in inaccurate determination of the rate constant of dissolving at the given temperature of experiment. The rate constant is a fundamental parameter characterizing the dissolving rate at a certain configuration. We will present a theoretical description of dissolving of a long metallic cylinder submerged into a melt column and relations for the rate constant determination from the time of the whole metallic cylinder dissolution are derived. In our experiments we performed the Cu dissolving in the Sn melt for the Cu cylinder (wire) diameters 0.8÷2 mm and the rate constant Ko (T = 600 °C) was determined. Relationships between the solid phase dissolving rate, i.e. the solid phase interface boundary movement c(t) in the melt, and rates of growth of intermetallic phases in the metal A will be observed. This procedure enables to create surface and subsurface layers of regulated thickness in metallic materials by means of reactive diffusion. ……………… DSL081 Dr. Sujay Chakravarty Institute of Metallurgy, Clausthal University of Technology, Robert‐Koch‐Str. 42, D‐38678 Clausthal‐Zellerfeld, Germany
Study of Self‐Diffusion in Nanocrystalline Iron Thin Films Using Neutron Reflectivity S. Chakravarty1, M. Horisberger2, J. Stahn2, H. Schmidt1 1Institute of Metallurgy, Clausthal University of Technology, Robert‐Koch‐Str. 42, D‐38678 Clausthal‐Zellerfeld, Germany. 2Laboratory for Neutron Scattering, ETH Zürich & Paul Scherrer Institut, CH‐5232 Villigen PSI, Switzerland Neutron reflectometry has the advantage over other methods of diffusivity determination, that diffusion lengths in the order of 1 nm and below can be determined. This enables diffusion experiments in a stable nanostructure, which is not modified by grain growth during annealing. In the present paper neutron reflectivity has been used to study self‐diffusion in nanocrystalline iron thin films. For diffusion studies, isotopically modulated periodic multilayers of the form Si/ [natFe(7 nm)/57Fe(3 nm)]20 were deposited using ion beam sputtering. A Bragg peak appears in the neutron reflectivity pattern of
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the multilayers due to a scattering contrast between natFe and 57Fe. This scattering contrast will be reduced due to isotope interdiffusion, which results in a decay in the height of the Bragg peak. From this decay diffusion length and diffusivity is calculated. Bulk self‐diffusivities in nanocrystalline iron has been measured as a function of time in a temperature range between 583 and 783 K. The determined diffusivities are strongly time depended and decrease by more than two orders of magnitude during isothermal annealing. In early stages, diffusion is dominated by structural point defects (interstitials or vacancies) present after deposition. The decrease in diffusivity is attributed to the annihilation of excess structural point defects apart from thermal defects present in the system. It has been observed that for very long annealing times the diffusivities above 673 K are in good accordance with volume diffusivities on single crystals given in literature. However, at temperatures below 673 K the diffusivities are higher than extrapolated literature data, even after annealing for 8 days. It is expected that at lower temperatures the excess defects are still present in considerable amounts. ……………… DSL161 Dr. Mohsen Haddad‐Sabzevar Department of metallurgy and Material Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
Thermal Properties and Crystallization Behavior of Co67Fe4Cr7Si8B14 Amorphous Alloy M. Haddad‐Sabzevar , S.Sahebian2, Z.Jamili3 Department of metallurgy and Material Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran. In order to investigate the crystallization behavior of the amorphous metallic alloys, the amorphous ribbons of Co67Fe4Cr7Si8B14 alloy were prepared by planar flow melt spinning process (PFMS). Differential Scanning Calorimetery (DSC) was used to analyze the thermal and crystallization behavior of the amorphous samples at two heating rates of 10 and 30 ◦C/min. The crystallization occurs at two stages. The crystallization kinetic at first stage was done by direct fitting of the experimental data to Avrami model. The results showed that the crystallization exothermic became wider and shifted toward a higher temperature range when the heating rate increased. The Avrami exponent (n) is independent of the heating rate, implying the same transformation mechanism as well. Activation energy was determined as 367.6 Kj/g by Kissinger analysis. Keywords: crystallization kinetics, Co amorphous alloy, DSC. References: [1]. J.D. Bernal, Nature 185, 68 (1960). [2]. S. Takayma, J. Mater.Sci. 11, 164(1960). [3]. P. Duwz, R.H.Willens, Klement, J. Appl.Phys. 31, 1136 (1960). [4]. N.J.Grant, B.C.Gissen (EDS.), Quenched Metals, MIT Press, (1976). [5]. M.G. Scott, In: F.E. Luborsky (Ed.), Amorphous Metallic Alloys, Butterworths, London, 144(1983). [6]. S. Lesz, R. Nowosielski, A. Zajdel, B. Kostrubiec, Z. Stoklosa, , International Scientific Journal, 28,91. [7]. H.F. Li, R.V.Ramanujan, Materials Science And Engineering A, 375‐377, 1087 (2004). [8]. H. Beck, H.J.Guntherodt (Eds.) Glassy Metals Ii, Atomic Structure And Dynamic , Electronic Structure, Magnetic Properties, (1983). [9]. S.R. Nagel, J. Tanc, Solid State Commun. 21, 129(1977). [10]. M. Haddad‐Sabzevar, Ribbon formation and solidification behaviour in the planar flow melt spinning process, Ph.D. thesis, KTH, Stockholm, Sweden, (1994). [11]. S.D.Kalushkin, I.A.Tomilin, Thermochim. Acta 280‐281, 303(1996). [12]. M. Joshi, B. S. Butala, Polymer 45, 4953 (2004). [13]. M. Avrami, Journal of Chemical Physics, 9 177 (1941). [14]. H.E.Kissinger, Anal. Chem. 29, 1702(1957). ……………… DSL307 Prof. Natalia Belousova Siberian Federal University, Russia
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Effect of Prehistory of Bi‐Sn Melts on the Kinetics of their Oxidation N.V. Belousova, E.O. Arkhipova Siberian Federal University, Krasnoyarsk, Russia The purpose of this work was to study kinetics of oxidation of Bi‐Sn melts at the temperature of 973 and 1173 K by the high‐ temperature gravimetry method. Previously bismuth was alloyed with Sn in the argon atmosphere and the prepared alloys were cooled to the room temperature. The time lapse to the beginning of oxidation experiments was varied from 1 to 20 days. After that samples were heated in the oven to the given temperature in the argon. The melts were oxidized in the air. The results of analysis show that the dependence of oxidation rate on the content of tin in the initial melt is complicated in form and the kinetics of this process is described by different laws. The alloys with 10, 20 and 40 at.% of Sn oxidize by parabolic oxidation law and so the process is limited by the diffusion of components through the scale. The melts containing more than 50 at. % of Sn oxidize by linear law. The most intricate dependence of weight increment on time was established in studies of the oxidation of 70 at. % Bi – 30 at. % Sn melts. The kinetics of this process is characterized neither parabolic law nor linear one. It was found that the oxidation features of these samples were determined by their prehistory. After long‐ term keeping of alloys at room temperature, the oxidation of melts was accompanied by the growth of the scales in the form of “tree” and its rate was much more than in other cases. It can be explained by the bursting of the compact oxide layer and by the oxidation of metal going up on the surface through the crack. Makeup melts oxidized without forming “trees”. It was established that the “tree” formed at 973 K was enriched in its upper part with bismuth oxide and Bi2Sn2O7; the lower part contained more than 50 mass. % of tin oxide, some quantity of metal bismuth, tin and also Bi2O3 and Bi2Sn2O7. The “tree” grown at 1173 K was the same in qualitative composition but the quantity of phase was different: in this case the main compound in both parts was Bi2Sn2O7. ……………… DSL341 Prof. Osamu Taguchi School of Nano and Advanced Materials Engineering, Changwon National University, Gyeongnam 641‐773, Korea
Reaction Diffusion in Pb Free Solder‐Cu System
O. Taguchi1,2, C.G. Lee2 , D.Y. Park2*, G.S. Shin2* and S. Suzuki1 Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980‐8577, Japan. 2 School of Nano and Advanced Materials Engineering, Changwon National University, Gyeongnam 641‐773, Korea. 2* Student, School of Nano and Advanced Materials Engineering, Changwon National University, Gyeongnam 641‐773, Korea. 1
Reaction diffusions in liquid Pb free solder- and solid Pb free solder- pure Cu systems have been investigated in the temperature range between 397 K and 563 K. The Pb-free solder of which composition is 95.7 mass% Sn, 2.8 mass% Ag, 1.0 mass% Bi and 0.5 mass% Cu and 99.99 mass% oxygen free Cu have been used. In the liquid Pb free solder-pure Cu system, as soon as the solder melt down, an intermetallic compound η phase has formed preferentially, and grown with increasing diffusion time. The interface between the η phase and the liquid solder is very irregular. Layer thickness of the η phase is obeyed the parabolic law. On the other hand, in the solid Pb free solder-pure Cu system two intermatallic compounds ε phase and η’ phase have been formed and grown with increasing time. Layer thickness of these intermetallic compounds have been obeyed the parabolic law. The growth rate of η’ phase is greater than that of ε phase.The growth kinetics of the intermetallic compounds and the diffusion behavior will be discussed. ……………… DSL363 Dr. Kozo Shinoda Tohoku University, Sendai 980‐8577, Japan
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Depth Resolved and Elemental Selective XRF and XAS in Surface Layer of Annealed Fe‐ Cr Alloys K. Shinoda1, S. Sato1, S. Suzuki1, H. Toyokawa2, H. Tanida2, T. Uruga2 1Tohoku University, Sendai 980‐8577, Japan. 2SPring‐8, Sayo, Hyogo 679‐5198, Japan. Cr in Fe‐Cr alloys often forms some different phase of oxides during annealing at high temperatures. The phases of Cr oxides are determined depending on the annealing condition such as temperature and oxygen partial pressure. In this study, depth‐ resolved X‐ray fluorescence analysis (XRF) of Fe and Cr were carried out using a two‐dimensional pixel array detector with geometrical arrangement of grazing exit in detection of fluorescence X‐ray emitted from sample surface, in order to characterize the depth‐directional distribution of the elements in the surface layers of Fe‐Cr alloys annealed under low oxygen partial pressure. In addition, depth‐resolved X‐ray absorption spectra will be also able to be obtained by measuring the incident X‐ray energetic dependencies of the fluorescence intensity. These techniques facilitate non‐destructive measurement of the elemental distribution and the phase of metal or oxides in depth direction. The experiments were performed at BL01B1 of SPring‐8 synchrotron radiation facility. The results showed that Cr was enriched and covered on the surface of the alloys during annealing and formed as Cr2O3 or FeCr2O4. The phase and thickness of formed oxides depended on the alloy composition and the annealing conditions. ……………… DSL426 Prof. Hiroshi Yukawa Department of Materials Science and Engineering, Nagoya University, Japan
Alloying effects on the hydrogen diffusivity during hydrogen permeation through Nb‐ based hydrogen permeable membranes H. Yukawa1, G.Z. Zhang1, M.Morinaga 1, T.Nambu 2, Y.Matsumoto 3 1 Department of Materials Science and Engineering, Nagoya University, Japan. 2 Department of Materials Science and Engineering, Suzuka National College of Technology, Japan. 3 Department of Mechanical Engineering, Oita National College of Technology, Japan. The hydrogen solubility and the hydrogen permeability of Nb‐based hydrogen permeable membranes are investigated in order to examine the alloying effects on the hydrogen diffusion coefficients during the hydrogen permeation under the practical condition. The hydrogen diffusion coefficient during the hydrogen permeation are evaluated from a linear relationship between the normalized hydrogen flux, J ⋅ d , and the hydrogen concentration difference, C, which are estimated form the PCT measurements, between the inlet and outlet sides of the membrane with the thickness of d. It is found that the hydrogen diffusion is found to be faster in Pd‐Ag alloy with face‐centered cubic (fcc) crystal structure than in pure niobium with body‐centered cubic (bcc) crystal structure at 773K under the practical condition of the hydrogen permeation. It is also found that the addition of Ru or W into niobium increases the hydrogen diffusion coefficient during the hydrogen permeation.
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Fig.1 shows the Arrhenius plots of the hydrogen diffusion coefficient for pure Nb, Nb‐5mol%Ru and Nb‐5mol%W alloys under the practical condition of the hydrogen permeation. It is shown that
the
-8
10
……………… DSL460 Prof. CHEOL‐WOONG YANG School of Advanced Materials Science & Engineering, Sungkyunkwan University, Suwon 440‐746, Korea
2
Diffusion coefficient, D / m s
it decreases by the addition of Ru or W into niobium.
but -1
activation energy for hydrogen diffusion in pure niobium is very large
Nb-5Ru
-9
10
Nb-5W Sample Pure Nb Nb-5W Nb-5Ru
Activation Energy 99 kJ/mol 78 kJ/mol 58 kJ/mol
Pure Nb
10Fig.1 Arrhenius plots of 1.2 diffusion coefficient 1.4 and
the hydrogen 1.6 the activation -1 1000/T /K energy for hydroten diffusion under the practical conditions of hydrogen permeation. -10
Phase formation between Pb‐free solder and electroless Ni‐P UBM H.B. Kang, J.H. Bae, J.W. Lee, M.H. Park, C.W. Yang School of Advanced Materials Science & Engineering, Sungkyunkwan University, Suwon 440‐746, Korea In flip chip interconnections using a solder bump, under bump metallization (UBM) is desirable because the solder cannot be bonded directly to the Cu pads. Of the many different UBM systems, electroless Ni‐P (EN‐P) has attracted considerable attention for flip chip bumping technology on account of its simple process and low cost. In the case of the interfacial reaction in Pb‐free solder/EN‐P system, the additional reaction layers (ternary Ni‐Sn‐P and P‐rich Ni layer) can be formed at Pb‐free solder/EN‐P interface. These additional layers can strongly affect the mechanical reliability of the Pb‐free solder joints. Therefore, it is essential to understand the formation and stability of the additional layers during reflow and aging processes. This study examined the additional reaction layers in Pb‐free solder/EN‐P UBM system using analytical transmission electron microscopy (AEM). AEM confirmed that the additional reaction layers do not consist of a single phase but are rather composed of two or three phases. After reflow process, the P‐rich Ni layer is composed of various Ni‐P phases (Ni3P, Ni12P5 and Ni2P) and Ni, while the ternary layer is a mixture of Ni2SnP and Ni3P. The stable Ni3P phase had formed at both the ternary and P‐rich Ni layers. During aging process, several meta‐stable Ni‐P phases in P‐rich Ni layer change into Ni3P phase because it is the more stable phase in the Ni‐P system. [1] K, Zeng and K.N. Tu, Mater. Sci. Eng. R. 38, 55 (2002). [2] V. Vuorinen, T. Laurila, H. Yu and J.K. Kivilahti, J. Appl. Phys. 99, 023530 (2006). ……………… DSL230 Mr. Kyeong‐II Kim
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Chungju National University, Korea
Evaluations of Hydrogen permeation on TiN‐20wt.%Co Membrane by Hot Press Sintering Kyeong‐Il Kim1, Whan‐Gi Kim2, Soon‐Chul Ur1 and Tae‐Whan Hong1 1Department of Materials Science and Engineering/Research Center for Sustainable Eco‐Devices and Materials(ReSEM), Chungju National University, 72 Daehak‐ro, Chungju‐si, Chungbuk 380‐702, Republic of Korea 2Department of Applied Chemistry, Konkuku University, 322 Danwol‐dong, Chungju‐si, Chungbuk 380‐701, Republic of Korea Nowadays, the most promising methods for high purity hydrogen production are membranes separation such as polymer, metal, ceramic and composites. It is well known that Pd and Pd‐alloys membranes have excellent properties for the hydrogen separation. However, it has hydrogen embrittlement and high cost for a practical applications. Therefore, most of scientists have searched new materials instead of Pd and Pd‐alloys. On the other hand, TiN powders are great in resistance to acids and chemically steady under high operating temperature. In order to get specimens for hydrogen permeation, the TiN powders synthesized were consolidated together with pure Co powders by hot press sintering. During the consolidation of powderss at HPS, heating rate was 10K/min and the pressure was 10MPa. It was characterized by XRD, SEM, and BET. Also, we estimated hydrogen permeability by Sievert's type hydrogen permeation membrane equipment. [1] E. Serra, E. Rigal, G. Benamati, Fusion Engineering and Design, 675‐679, 49‐50 (2000) [2] Barbara Ernst, Stephane Haag, Michel Burgard, J. Membrane Science, 208‐217, 288 (2007). [3] M.D. Dolan, N.C. Dave, A.Y. Ilyushechkin, L.D. Morpeth, K.G. McLennan, J. Membrane Science, 30‐55, 285(2006). ……………… DSL202 Mrs. Divya V.D. Department of Materials Engineering, Indian Institute of Science, Bangalore – 560012, India
Interdiffusion studies in Co‐Mo system V.D. Divya, U. Ramamurty and A. Paul Department of Materials Engineering, Indian Institute of Science, Bangalore – 560012, India The study on the formation and growth of topological closed packed (TCP) compounds is important to understand the performance of turbine blades in jet engine applications. These deleterious phases grow mainly by diffusion process in the superalloy substrate and interdiffusion zone between substrate and bond coat. The major element Co and minor element Mo promotes the formation of m phase. In this study, growth kinetics and different diffusion parameters, like interdiffusion, intrinsic and tracer diffusion coefficients are calculated in the m phase in the Co‐Mo system. Further the activation energy, which provides the idea about the mechanism, is determined. ……………… DSL315 Mr. Dmitry Leonov Technical Centre, N.A.S. of Ukraine, 13 Pokrovs’ka Str., UA‐03070 Kyiv, Ukraine
Kinetics Parameters of Atomіc Migration and Diffuse Scattering of Radiations within the (Ti, W)B2 Alloys D.S. Leonov1,a, V.A. Tatarenko2,c M.P. Semenko3,b, O.V. Sobol4, and Yu.A. Kunitsky1 1Technical Centre, N.A.S. of Ukraine, 13 Pokrovs’ka Str., UA‐03070 Kyiv, Ukraine
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2Department of Solid State Theory, G.V. Kurdyumov Institute for Metal Physics, N.A.S. of Ukraine, 36 Academician Vernadsky Boulevard, UA‐03680 Kyiv‐142, Ukraine 3National Taras Shevchenko university of Kyiv 64 Volodymurska Str., UA‐01033 Kyiv, Ukraine 4Kharkov State Polytechnical University, 21 Frunze Str., UA‐61002 Kharkov, Ukraine
[email protected],
[email protected],
[email protected] Keywords: short‐range order, ordering kinetics, electrical resistance, diffuse scattering. Abstract. Relaxation of diffuse‐scattering intensities of various kinds of waves is a phenomenon of especial interest since its study enables one to obtain the most detailed information on both equilibrium SRO and nonequilibrium SRO, and therefore, it is the most convenient instrument for investigating SRO kinetics. The short‐range order kinetics is studied by the use of obtained data of measurements of electrical resistivity for substitutional (Ti,W)B2 [1] solid solutions during the isothermal annealing. Within the framework of the first‐order and (more realistic) second‐order kinetics models, the maximum characteristic relaxation times and equilibrium values of the residual electrical resistivity for these solid solutions at different annealing (619–638 K) and quenching temperatures are evaluated on a base of experimental data. The maximum characteristic relaxation times for diffuse scattering of radiations in these solid solutions are obtained within the framework of hypothesis about identity of maximum characteristic relaxation times of radiation diffuse scattering and electrical resistance. The curves of time dependence of normalized radiation diffuse‐scattering intensity corresponding to the wave‐vector star, which dominates in a mapping structure of the short‐range order, at different quenching and annealing temperatures are also obtained for (Ti,W)B2 solid solutions [2]. References [1] A. P. Shpak, O. V. Sobol, V. A. Tatarenko et al.: Metallofiz. Noveishie Tekhnol., 30, No. 3: 285–295 (2008). [2] A.G. Khachaturyan: Theory of Structural Transformations in Solids (Wiley, New York 1983). ………………
DSL056 Mr. Arash Rezaei
Investigation of Dynamic Recrystallization in an Al‐Li‐Cu‐Zr(‐Mg) Alloy A. Rezaei1,a S. Ahmadi2, , A. Shokuhfar3 a
[email protected] 1‐ Graduated in Master of Science in metallurgy, K. N. Toosi University of Technology, Faculty of Mechanical Engineering, Department of Material Science, Tehran. Iran 2‐ Ph.D student, Tarbiat Modares University, Faculty of Engineering, Division of Material Science, Tehran. Iran 3‐ Professor, K. N. Toosi University of Technology, Faculty of Mechanical Engineering, Department of Material Science, Tehran. Iran In this investigation, dynamic recrystallization phenomenon (DRP) of an Al‐Li‐Cu‐Mg‐Zr alloy was studied in two temperatures, 350°C and 400°C. Wedge samples were subjected to hot rolling deformation in both temperature and one passes. For wedge specimens, reduction up to 70% was considered. Results showed that grain size of the specimens after hot rolling decreases from 100μm to 30μm because of DRP. Furthermore, it is observed that critical reduction for starting DR at 400°C is 40% and at 350°C reduction must increase to 50%. Keyword: dynamic recrystallization, critical reduction, hot rolling, microstructure ……………… DSL215 Mr. NitinTanaji Kumbhar Materials Science Division, Bhabha Atomic Research Centre, Mumbai ‐ 400 085, India
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Interdiffusion and Interface Structure in AA 6061/AA 5052 Friction Stir Welded Joints N. T. Kumbhar and K. Bhanumurthy Materials Science Division, Bhabha Atomic Research Centre, Mumbai – 400 019, India Friction Stir Welding (FSW) is a solid state joining process in which weld is made by a rotating, non‐reactive tool through the constrained mating surfaces of a joint. Extensive work is reported for joining high quality joints of Al alloys, Mg alloys, and Cu alloys. In addition, considerable progress has been made in modeling the deformation mechanism in the weld zone [1]. The important aspect of interdiffusion at the welded interface is not extensively studied [2]. The study of diffusion at the interface in similar alloys may involve local intermixing. Experimental determination of the diffusing species is not easy in this case. In view of this, two Al alloys with nominal change of Mg and Si composition but with nearly similar hot deformation characteristics were chosen for understanding the extent of interdiffusion at the interface. Experimental work involved FSW of AA 6061/AA 5052 of 5 mm thick plates. In order to understand the flow behaviour and extent of interdiffusion two types of FSW joints were made with nearly same heat inputs but in two different configuration i) AA 6061/ AA 5052 (AA 6061 on advancing side) ii) AA 5052/ AA 6061 (AA 5052 on advancing side). In addition, diffusion couples between AA 5052 and AA 6061 were made and annealed for 7.2 ks in the temperature range 450 °C to 600 °C. The interface structure was serrated on the top and bottom of the weld zone, but was nearly planar at the center. The extent of interdiffusion at the centre of weld zone was analyzed by measuring the composition profiles of Mg, Si and Al electron probe micro analyzer (EPMA). The interdiffusion distances in FSW species was attributed to in situ diffusion and local heating. An attempt has been made to arrive at the diffusion coefficients using Hall’s method. The experimental work presents details of microstructure and interdiffusion in FSW specimen and also attempts to compare these interdiffusion distances with the diffusion couples by conventional methods. [1] S. Mandal and K. Williamson, J. Materials Processing Technology, 174, 190, (2006). [2] R. Ayer, H.W. Jin, R.R. Mueller, S. Ling and S. Ford, Scripta Materialia, 53, 1383, (2005). ……………… DSL246 Dr. Min‐Su Han Division of Marine Engineering, Mokpo Maritime University, Mokpo City, Jeonnam 530‐729, Korea
The Investigation on Corrosion and Optimum Corrosion Protection Potential of STS 316L in seawater M. S. Han, J. C. Park, Y. B. Woo, S. K. Jang, S. J. Kim Division of Marine Engineering, Mokpo Maritime University, Mokpo City, Jeonnam 530‐729, Korea Austenitic stainless steels have problem such as pitting, intergranular corrosion and stress corrosion cracking, which causes severe damage of structure in spite of high toughness and mechanical strength[1‐3]. To minimize these disadvantages in offshore structures demand of STS 316L which has small amount of C and has Mo is increasing. In this paper, the electrochemical experiments are executed to evaluate the durability at various protection potentials on stress corrosion cracking and hydrogen embrittlement of STS 316L in natural sea water environment. The polarization trend for STS 316L shows the effects of concentration polarization due to dissolved oxygen reduction reaction and activation polarization due to hydrogen gas generation. The turning point of two reactions in the polarization curve presented ‐0.92V(vs. Ag/AgCl). The lowest current densities in the potentostatic test and non‐correded surface condition of specimens by SEM analysis presented at potentials of 0 ~ ‐0.9V and 0.4 ~ ‐0.9V, respectively. Synthetically, the optimum corrosion protection range without stress corrosion cracking and hydrogen embrittlement is concluded with the potential range of ‐0.56 V ~ ‐0.92 V. [1] S. J. Kim, M. S. Han, J. I. Kim, K. J. Kim, J. Kor. Inst. Surf. Eng., 40(5), pp. 234‐240, (2007) [2] S. J. Kim, J. Y. Ko, M. S. Han, Korean J. Chem. Eng., 23(6), pp. 1028‐1033, (2006) [3] M. S. Han, S. C. Ko, S. K. Jang, S. J. Kim, Meters and Materials International, 14(2), pp. 203‐211, (2008)
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……………… DSL344 Mrs. Yuliya Khalimullina
Electrode position of Lead Ions Under the Diffusion Kinetics Conditions P.A. Arkhipov1, Yu.P. Zaikov1, V.V. Ashikhin2, Yu.R. Khalimullina2 1The Institute of High Temperature Electrochemistry, Ural Branch of Russian Academy of Science, S. Kovalevskaya/Academicheskaya St, 22/20, 620219 Yekaterinburg, e‐mail:
[email protected] 2Open Joint‐Stock Company ELECTROMED, Scientific Research Centre, Lenin St, 1, 624091, Verkhnyaya Pyshma The cathode polarization processes taking place at the tungsten electrode surface were under investigation at temperature range 450‐550 ºC. The electrode was placed at the LiCl‐KCl equimolar molten mixture containing lead chloride and lead oxide. The mechanism of lead ions electro‐reduction in chloride and oxide‐chloride melts was proposed. Limiting diffusion current density of lead ions electro‐deposition was found to decrease with lead oxide addition. It is due to Pb2OCl2 formation. Bivalent lead diffusion coefficients in LiCl‐KCl‐PbCl2 melt were determined by chronopotentiometric method. The analysis of the processes taking place on tungsten electrode at oxide‐chloride melts has been made. ……………… DSL405 Dr. Prasad Tiwari Post Irradiation Examination Division, Bhabha Atomic Research Centre, Mumbai‐40085, India
Stress Induced Migration of Hydrogen in AISI 403 Steel G.P.Tiwari. V.D.Alur and E.Ramadasan Post Irradiation Examination Division, Bhabha Atomic Research Centre, Mumbai‐40085, India The paper presents the hydrogen concentration profile on tensile test specimens which have been charged electrolyticaly with hydrogen. In particular, the role of externally applied tensile stress in enhancing the ingress of hydrogen and its accumulation within the specimen is emphasized. A standard 8mm ASTM tensile specimen has been employed. One end of the specimen is extended. This extended portion serves as a cathode during electrolytic charging. A platinum wire mesh is used as anode. In order to facilitate the application of load during charging, the specimen is firmly held in a specially designed fixture with the help of threads which are provided on either ends of the gauge section. A notch is provided in the gauge section to create a stress gradient. At the end of charging, 3 mm thick disc specimens are cut from the specimen and analyzed for their hydrogen content using inert gas fusion technique. The main advantage of this charging procedure is that test portion of the specimen does not come into contact with the electrolyte during charging. Hence, microstructural damage to the specimen during the entry of high fugacity hydrogen in the matrix is avoided. Hydrogen reaches the test portion of the specimen via diffusion through the matrix. An analysis of the results brings about following characteristic features of hydrogen behavior during electrolytic charging in to the steel: 1. Presence of tensile stress enhances the rate of hydrogen within the matrix. Hydrogen displays high propensity to collect in sections of the specimens which have been under tensile load during electrolytic charging. 2. In the absence of stress, diffusion down the concentration controls the hydrogen distribution within the specimen. 3. Surface area has an important role in the accumulation of hydrogen across any section in the specimen. If the available surface area is more, local hydrogen concentration is enhanced. The effect of external coating on the ingress of the hydrogen into the specimen has also been investigated. The sheathing of the specimen with a 3 mm thick jacket of pure uranium caused a very significant change in the hydrogen concentration along the entire length of the specimen. The concentration of hydrogen at some sections rose 8‐10 times higher than that obtained in the absence of uranium sheathing. However, the presence of a 100 µm thick coating of titanium in the charging section of the specimen did not cause any improvement in the hydrogen concentration of the specimen. ……………… DSL499
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Mr. M. Asadi Materials Science and Engineering, Kerman, Iran
Film Formation via Plasma Electrolyte Oxidation of Ti and Ti‐5Mo‐4V‐3Al Alloy in High Alkaline Solutions M. Asadi*1, 2, Mehdi Attarchi1,3, M. Vahidifar1, 2 , A. Jafari1 1Materials Science and Engineering, Bahonar Kerman, Kerman, Iran 2Materials Science Department, Yazd Azad University, Yazd, Iran 3Materials and Energy Research Center, Tehran, Iran *Corresponding Author This work investigates the characteristics of oxide films formed on Ti and the Ti alloy through plasma electrolyte oxidation (PEO) process in highly alkaline medium in the presence or absence of phosphate ions. The obtained coatings showed different characteristics when they formed in high alkaline phosphate solutions particularly was anatase for Ti and rutile/titanium phosphate for the Ti alloy layer. Films formed in aqueous solution without KOH caused a reduction in current density and also reduced the number of microarcs, while in electrolytes with high OH‐ concentration, the current was low and the density of sparks was significant. Keywords: Ti; Thick Films; Plasma Electrolytic Oxidation ……………… VIP‐DSL033 Prof. Huseyin Cimenoglu
An Investigation On Air Oxidation Behaviour of a Ti‐6Al‐7Nb Alloy Mehtap Deniz Unlu, Onur Meydanoglu and Huseyin Cimenoglu* Istanbul Technical University Department of Metallurgy and Materials Engineering 34469 Maslak – Istanbul Air oxidation behavior of a Ti–6Al–7Nb alloy was examined over the temperature range of 600–900 ◦C for different time intervals ranging between 12 and 72 h. Results of the oxidation tests were evaluated according to the following equations; ΔW/A= K.t 1/n and K=K0 exp (‐Q/RT) where ΔW is the weight gain of the samples after oxidation (mg), A is the total surface area of the samples (cm²), t is oxidation time (hour), n is the reaction index (the kinetic model is linear if n =1 and parabolic if n=2), K is the rate constant, Ko is the frequency factor, Q is the activation energy, R is the gas constant (8.3143 J/mol K) and T is reaction temperature (K). Present study revealed that air oxidation of Ti‐6Al‐7Nb alloy obeyed parabolic kinetics in between 600 and 900 ◦C, by yielding activation energy of 128 kJ/mol. *Corresponding author: Tel: +90‐212‐285‐6834 Fax: +90‐212‐285‐3427 E‐mail:
[email protected] ……………… VIP‐DSL028 Prof. Dezső L. Beke
Composition and Pressure Dependence of the Self‐Diffusion Coefficient in Liquid Metals Dezső L. Beke Department of Solid State Physics, Institute of Physics, University of Debrecen, 4010, Debrecen, P.O.Box.2, Hungary,
[email protected]
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First a minimum derivation of the temperature dependence of D is provided (minimum derivation in the sense that it states only that the reduced (dimensionless) D should be a universal function of the reduced temperature) will be presented, using the similarity of interatomic potentials and dimensional analysis Then this relation will be extended for the determination of the pressure and composition dependence of the self‐diffusion coefficients by the use of pressure and composition dependent scaling parameters (melting point, atomic volume and mass). The obtained universal form (valid for binary liquid alloys) is very useful for the estimation of the temperature, composition and pressure dependence of the self‐diffusion coefficients. ……………… VIP‐DSL043 Prof. M. A. J. Somers
The Influence of Stress on Diffusion – Carbon Diffusion Data in Austenite Revisited Thomas L. Christiansen & Marcel A.J. Somers Technical University of Denmark, Department of Mechanical Engineering, Kemitorvet b. 204, DK‐2800 Kgs. Lyngby, Denmark Generally, in interstitial systems concentration variations of the interstitial component induce a relatively large stress variation as compared to substitutional systems. The assessment of diffusion data from interstitial diffusion experiments under the influence of a (steep) concentration gradient will inevitably be the combined influence of compositional and a composition‐induced stress on the chemical potential gradient. Usually, the presence of (composition‐induced) stress is not taken into consideration on the determination of the (composition‐dependent) diffusivity of interstitials from experiments involving a composition profile. Consequently, a vast number of published diffusion data on interstitial systems are likely to be flawed by these composition induced stress effects. The present paper exemplifies this point by examining the influence of stress on published diffusion data for carbon in austenite [1]. To this end a numerical model for the simulation of diffusion controlled concentration profiles in austenite under para‐equilibrium conditions with a gaseous atmosphere is adopted [2]. The simulated composition profiles resemble those in Ref.1 and are evaluated with models including and excluding the composition‐induced stresses. It is shown that neglecting composition‐induced stress leads to erroneous values for the concentration‐dependent diffusion coefficient of carbon in austenite. The simulations will be discussed in the light of existing diffusion data and implications for systems with colossal interstitial solubility as in expanded austenite [3] will be pointed out. [1] C. Wells, W. Batz, R.F. Mehl, Transactions AIME, 188 (1950) 553. [2] T. Christiansen, K.V. Dahl, M.A.J. Somers, Materials Science and Technology 24(2) (2008) 159 [3] T.S. Hummelshøj, T.L. Christiansen, M.A.J. Somers, in preparation ……………… VIP‐DSL000 Prof. Andreas Oechsner Department of Applied Mechanics, Technical University of Malaysia, 81310 UTM Skudai, Johor, Malaysia
On the Physics of Some Known Diffusion Anomalies in Metallic Systems Yu.S. Nechaev1 and A. Öchsner2 1Kurdjumov Institute of Metals Science and Physics, Bardin Institute for Ferrous Metallurgy,Vtoraya Baumanskaya St., 9/23, Moscow 105005, RUSSIA . 2Department of Applied Mechanics, Technical University of Malaysia, 81310 UTM Skudai, Johor, MALAYSIA.
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In this contribution, some long‐term and recent open questions on mechanisms (physics) of a number of the known diffusion anomalies in deforming, deformed, nano‐structured, amorphous and liquid‐solid metallic systems are considered. It includes a constructive critical analysis and re‐treatment of the data on: 1) anomalies of diffusion of hydrogen in deformed, nano‐ structured and amorphous Pd, Fe, steels, …; 2) anomalies of diffusion of Fe and other transition impurities in Al, particularly, at grain boundaries; 3) anomalies of the tracer diffusion in nano‐structured metals and alloys (Ni in Cu, Ni, Fe, Ag in Ni‐Fe, …); 4) anomalies of diffusion processes in intensively deforming metals and alloys, particularly, in the ball milling ones (Ti‐Cr, Ni‐ Zr, Cr‐Zr, …); 5) anomalies of diffusion processes of internal oxidation and nitridation of Fe‐Cu and Ni‐Cr alloys, particularly, the precipitate coarsening anomalies; 6) diffusion anomalies of the liquid‐metal deep etching of the grain boundary regions in Cu‐Bi and others; 7) diffusion anomalies of the grain boundary faceting in Zn‐Al and others. The mechanisms (physics) of these anomalous diffusion processes are considered on the basis of using the analytical results [1‐7]. ]1] Yu.S. Nechaev. Solid State Phenomena, 138, 91 (2008). [2] Yu.S. Nechaev. Diffusion and Defect Forum, 251‐252, 111 (2006). [3] Yu.S. Nechaev. Diffusion and Defect Forum, 251‐252, 123 (2006). [4] Yu.S. Nechaev. Physics‐Uspekhi, 51, #7, 681 (2008). [5] Yu.S. Nechaev and G.A. Filippov. Defect & Diffusion Forum, 194‐199, 1099 (2001). [6] Yu.S. Nechaev. Izvestija Akademii Nauk, Serija Fizicheskaja (Transactions of the Russian Academy of Sciences, Physical Series), 65, # 10,1399 (2001). [7] Yu.S. Nechaev and A. Öchsner. Defect and Diffusion Forum, 283‐286, 545 (2009).
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Diffusion in Amorphous Materials
DSL275
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Dr. Kazumasa Yamada Dept of Electrical and Electronic Engineering, Hakodate National College of Technology, Tokura‐cho 14‐1, Hakodate, 042‐8501, Japan
Structural relaxation process by addition of B in CuHfTi amorphous alloys K. Yamada1, N. Miura1, A. Yamamoto1, I. A. Figueroa2, H. A. Davies2, I. Todd2 1Dept of Electrical and Electronic Engineering, Hakodate National College of Technology, Tokura‐cho 14‐1, Hakodate, 042‐ 8501, Japan. 2Dept of Engineering Materials, University of Sheffield, Sheffield S1 3JD, UK. Cu has been shown to be good base element for bulk glass‐forming alloy with fully glassy sections recently by using die injection casting [1]. Binary Cu ‐ (Zr or Hf) alloys have been found to form an amorphous phase over a wide composition range. However, addition of Ti in both these binary systems greatly increased the glass forming ability (GFA), with the critical diameter for fully amorphous rods being at least 4 mm for Cu60Zr30Ti10, Cu60Hf20Ti20 and Cu55Hf25Ti20 [1]. Meanwhile the understanding of the structural relaxation process is essential in the development of stability for amorphous alloys, as well as in establishing stable working temperature to avoid the degradation of strength. The aim of this research is to clarify a quantitative evaluation in the structure relaxation processes focusing on the activation energy in Cu based amorphous alloys. The specimens of amorphous Cu‐Hf‐Ti, Cu‐Hf‐Ti‐B (1% of B) and Cu‐Hf‐Ti‐B (3% of B) ribbon were prepared by liquid quenching method with single‐roll spinner. The endothermic heat that was released in relaxation process through annealing time and temperature was measured using a Differential Scanning Calorimetry (DSC) [2]. Furthermore the distributions for the Activation Energy Spectrum (AES) were observed almost energy range from 140 to 150 kJ/mol. The main result has been established that AES model energy distribution though the structure relaxation occurs even in amorphous Cu‐Hf‐Ti and Cu‐ Hf‐Ti‐B alloys. [1] I. A. Figueroa, H. A. Davies, I. Todd and K. Yamada, Adv. Eng. Mater., 9, 496 (2007). [2] K. Yamada, K. Fukamichi, Y. Iijima, Proc. Magneto‐Optical Recording Intl. Symp. ‘97, J. Magn. Soc. Jpn., 22, Suppl.S2 97 (1998). ……………… VIP‐DSL063 Prof. Dr. Nicola Bianco Universita' degli Studi di Napoli Federico II, Italy
Numerical Investigation on Transient Conjugate Optical‐Thermal Fields in Thin Films Irradiated by Moving Sources for Back and Front Treatments N. Bianco1, O. Manca2, D. Ricci2 1DETEC, Università degli Studi Federico II, Piazzale Tecchio 80, 80125 Napoli, Italy 2DIAM, Seconda Università degli Studi di Napoli, Via Roma 29, 81031 Aversa, Italy Manufacturing of multilayer thin films deposited on glass substrate is accomplished by means of laser sources. The analysis of thermal conductive and optical distributions is of paramount importance to broaden the fields of applications for manufacturing, so computational investigations of laser interactions with single and multilayer thin films on a glass substrate have been performed [1,2]. The heat source can either directly impinge the film surface (front treatment), or the glass substrate (back treatment). In this paper the bidimensional conjugate non‐linear thermal‐optical time dependent problem is numerically analyzed. A Nd‐Yag laser with wavelength of 1064 nm and Gaussian beam impinging on a a‐Si/TCO/glass multilayer structure have been considered. The Peclet number is the main non‐dimensional parameter governing the heat transfer mechanism in the system. The dimension along the moving direction is semi‐infinite and simulations have been carried out by means of COMSOL Multiphysics 3.4 for different Pe numbers and initial position of beam spot. Results are presented in form of spatial and temporal temperature profiles as well as absorbed heat transfer rates inside the layers. The accomplished analysis shows that the BT processes are more efficient in terms of manufacturing processes, oriented to the production of photovoltaic cells.
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References [1] R.K. Shah, H.Md. Roshan, M.K. Sastri, and K.H. Padmanahan, Thermomechanical Aspect of Manufacturing and Material Processing (1992). [2] C.P. Grigoropoulos, Heat Transfer in Laser Processing of Thin Films, Annual Review of Heat Transfer, Vol. 5, Chap. 2, pp. 77‐130, C. L. Tien ed., CRC (1994). ……………… VIP‐DSL011 Prof. A. N. Dmitriev
Influence of Elements Oxides Microadditives with Major Cationic Radius on Properties of Silicate Bundle A.N. Dmitriev, V.P. Perepechaev, Yu.A. Chesnokov Institute of Metallurgy of Ural Branch of Russian Academy of Sciences, 101 Amundsen st., Ekaterinburg, 620016, Russia For the agglomerates of the Kachkanar deposit iron ore the role of elements with major than for magnesium and calcium ionic radius in the formation of the strength characteristics and parameters of the viscous‐plastic state of iron‐ore materials is shown. The strength characteristics of high‐quality sinters are largely defined by the low stressed state of a silicate bundle which is formed in the cake cooling‐down period. The diffusion processes at the glasses recrystallization at the cakes refrigeration can be reduced by injection of the elements braking these processes and having the low ¬strength cation‐ oxygen of connections, that, apparently, should ¬ hinder in formation of the crystals with their participation. From these positions the stabilizing additions are the cations of heavy elements having major radius and remote from the kern valence electrons¬. It according to the theory of the stressed state of the oxide ¬ systems is accompanied by the grain refinement, decrease of the microstresses ¬ and fissurings of the glass matrix and therefore the defectiveness of cake structure [1]. On the basis of the mathematical model leaning on the results of the dilatometric explorations the positive influence of the microadditives of the barium oxide on increase of temperature of beginning and narrowing of the softening range of sinters is revealed. [1] V.A. Gorbachev and S.V. Shavrin. Thermal microstresses in cakes. (Science, Moscow, 1982).
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Mass Transport and Related Phenomena in Non‐ Metallic Materials
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DSL026 Dr. Harald Schmidt Clausthal University of Technology Institute of Metallurgy Robert‐Koch‐Str. 42 38678 Clausthal‐Zellerfeld Germany
Self‐diffusion Studies on the Sub‐nanometre Scale using Neutron Reflectometry E. Hüger, S. Chakravarty, H. Schmidt Clausthal Univesrity of Technology, Clausthal‐Zellerfeld, Germany We present the method of neutron reflectometry, which allows the detection of extremely small diffusion lengths below 1 nm at corresponding low self‐diffusivities down to 1 x 10‐25 m2/s [1‐3]. Such a combination of values cannot be achieved by conventional methods of diffusivity determination, like the radiotracer method, secondary ion mass spectrometry or nuclear magnetic resonance. With our method the extensive characterization of materials which are in a non‐equilibrium state, like amorphous or nano‐crystalline solids becomes possible. Due to the small experimentally accessible diffusion lengths simultaneously occurring micro‐structural changes (grain growth and crystallization) can avoided during the actual diffusion experiment. Neutron reflectivity is measured for so‐called isotope multilayers, which are chemical homogeneous but isotope modulated layers (e. g. [natGe(20 nm)/71Ge(20 nm)]10). These structures are produced by magnetron sputtering or molecular beam epitaxy in form of thin films. Due to the different coherent neutron scattering lengths of the stable isotopes Bragg peaks occur in the reflectivity spectrum. Due to interdiffusion of the isotopes after annealing at elevated temperatures the Bragg peaks decay, where from diffusivities can be determined. We will illustrate this technique for the model systems amorphous silicon (carbo‐)nitride, single crystalline germanium and nano‐crystalline iron. [1] H. Schmidt et al. Phys. Rev. Lett. 96 (2006), 055901. [2] H. Schmidt et al. Acta Mater. 56 (2008), 464. [3] E. Hüger, H. Schmidt et al., Appl. Phys. Lett 93 (2008), 162104. ……………… VIP‐DSL040 Prof. P. S. Pizani Universidade Federal de São Carlos‐UFSCar, BRAZIL
Raman Scattering Studies of Non‐Hydrostatic Pressure‐Induced Phase Transitions and Multiphase State Generation in Semiconductors Paulo S. PIZANI1) and Renato G. JASINEVICIUS2) 1) Universidade Federal de São Carlos Departamento de Física Caixa Postal 676 13 565‐905 São Carlos, SP Brazil E‐mail:
[email protected] 2) Universidade de São Paulo Escola de Engenharia de São Carlos Departamento de Engenharia Mecânica Caixa Postal 369 13 560‐000 São Carlos, SP Brazil E‐mail:
[email protected]
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The application of high non‐hydrostatic pressure via Vickers microindentations, single point diamond turning and mechanical impact may lead to structural phase transitions and to the generation of multiphase state of elemental and compound semiconductors. To characterize these effects in crystalline and amorphous Si, GaAs, GaSb and InSb, Raman scattering was used in the micro Raman configuration. In the present work it will be discussed about the reversibility of these pressure‐ induced structural phase transitions. In silicon for example, the results indicated that the formation of multiple phases by cyclic microindentations may depend even on the crystallographic direction and number of successive cycles. Starting from amorphous Si, it is impossible to generate other phases, indicating the irreversibility of this transition. For all studied semiconductors, the high non‐hydrostatic pressure applied by the diamond tool tip during the machining process in the ductile regime lead to the surface amorphization. The crystalline state of the worked surface can be recovered by thermal annealing only in elemental semiconductors. For the compound semiconductors, the multiphase state was achieved only by applying high energy mechanical impact, where the compression/decompression rate is about some tenths of microseconds. ……………… VIP‐DSL055 Dr. Cornelia Breitkopf Technische Universität München Institute for Chemical Technology Lichtenbergstr. 4 D‐85748 Garching, Germany
Diffusion and Reaction in hierarchically structured metal Oxides ‐ a transient TAP study M. Galinsky1, M. Lutecki1, C.Breitkopf2 1University of Leipzig, Linnéstr. 3, 04103 L Leipzig, D. 2TU München, Lichtenbergstr. 4, 85747 Garching, D. Porous metal oxides are highly recognized as valuable catalytic materials. Among them, sulfated zirconias (SZ) have found several applications and due to its properties it is a promising catalyst system for a variety of reactions of industrial importance. Especially the n‐butane isomerization proceeds already at very low temperatures on SZ making it to an interesting catalytic material compared to commercially used catalysts [1]. Regarding the improved synthesis available today for catalyst preparations by use of blockcopolymers as templates and structure directing agents [2], the morphology of SZ can be systematically modified over the whole nanometer scale. However, there is no comparative study regarding the diffusion of reactants in these newly designed porous systems, which may influence the microkinetics significantly. In this study a transient method ‐ temporal analysis of products ‐ was used to investigate the diffusion of several probe molecules including the reactant n‐butane in SZ materials of different pore size. The preparation of SZ with wide variations in their pore sizes is described in [3]. Single pulse experiments were performed to characterize (i) diffusion only for non‐ adsorbing probes like Ne or N2 and (ii) diffusion processes with additional recognition of adsorption and desorption for probes like alkanes, alkenes and CO2. Knudsen diffusion coefficients for all probe molecules are modeled depending on the porosity and are compared to those of the reactant n‐butane [4]. Moreover, temperature dependent measurements allowed additionally the estimation of heats of adsorption [5]. [1] A. Chica, A. Corma, J. Catal., 187, 167, (1999). [2] M. Lutecki, C. Breitkopf. Appl. Catal. A Gen. 352, 171, (2009). [3] M. Lutecki, C. Breitkopf, submitted to Micropor. Mesopor. Mat.. [4] C. Breitkopf, M. Galinsky, Proceedings of 6th International Conference on Computational Heat and Mass Transfer, May 18–21, 2009, Guangzhou, China. [5] C. Breitkopf, J. Mol. Catal. A: Chemical, 226, 269, (2005). ……………… DSL113 Prof. Jan Ma
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School of Materials Science and Engineering, Nanyang Technological University Singapore 639798
Modeling of Densification of Nano‐sized Ceramic Materials Jie Lu1 and Jan Ma1,2 1School of Materials Science and Engineering, Nanyang Technological University Singapore 639798 2Temasek Laboratories, Nanyang Technological University Singapore 639798. Nano‐sized ceramic materials are well accepted to possess good mechanical properties. These materials are normally obtained by sintering of nano‐sized powders, however, there exists very limited reports on the constitutive modeling of the process using nano‐sized materials. Classical linear governing laws have been well reported for such applications, nevertheless, it has been recently noted that for sintering of submicron and smaller size powders, a linear relationship tends to over‐estimate the process. In the present work, a non‐linear constitutive relationship is proposed for the sintering of nano‐sized materials, and its application on constrained sintering is also discussed. Experimental results are also used to verify the models. Mechanical properties of a thin coat of nanomaterials on a coarse grained substrate are also characterized. ……………… DSL214 Prof. Vladimir Skidanov Institute for Design Problems in Microelectronics RAS Moscow 124681 Russia
Fe Ions Diffusion in B‐Doped Czochralsky Silicon Crystal during Thermo‐Donors Annealing Process V.A. Skidanov Institute for Design Problems in Microelectronics RAS, Moscow, Sovetskaja street 3, 124681, Russia. Transient metals are known as the most harmful contaminants in silicon microelectronics. Silicon bulk contamination is provided at the early chip fabrication technology stage due to utilizing of Fe, Ni containing instrumentation at crystal cutting process and successive thermodonors annealing. Drastic enhancement of optically activated Fe ion minority carriers recombination capability was used for measurement of interstitial Fe ions concentration in p‐type Czochralsky silicon by Surface Photo‐Voltage Technique (SPV) [1]. Two millimetres thick silicon slabs were contaminated artificially by Fe on one of two surfaces. Then Fe diffusion from silicon surface into crystal bulk during thermo‐donors annealing (650 ºC, 30 min.) was observed by two different methods. First method is Fe concentration normal to surface distribution measurement after one‐ time annealing process and successive silicon slab layer by layer chemical etching. The second method is observation of Fe concentration evolution near both slab surfaces during multiple annealing processes. Fe concentration measurements were made by SPV Technique after each etching or annealing step. Highly reproducible profiles of Fe ions distribution after one‐ time annealing were determined by first method with Fe penetration effective depth ~200 mcm. Gradual Fe concentration reduction near preliminary contaminated surface and Fe concentration increase near opposite surface were observed during multiple annealing processes. Fe concentrations near both surfaces become equal after approximately 10‐times annealing in agreement with concentration profile depth obtained by first method. Broken layer was found to be effective source of Fe contamination during annealing if it is made without lapping stage in modern wafer fabrication process. [1] A.A. Istratov, H. Hieslmair, E.R. Weber, Appl. Phys. A 70, 489 (2000). ……………… DSL257 Dr. Djamshid Khatamian Materials and Mechanics Branch, AECL, Chalk River Laboratories, Stn. 55 Chalk River, ON K0J 1J0, CANADA
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Diffusion of Hydrogen in Single Crystals of Monoclinic‐ZrO2 and Yttrium Stabilized Cubic Zirconia D. Khatamian AECL, Chalk River Laboratories, Chalk River, ON K0J 1J0, CANADA In modern CANDU® power reactors, pressure tubes of cold‐worked Zr‐2.5Nb (Zr‐2.5 wt% Nb) material are used in the reactor core to contain the fuel bundles and the heavy water (D2O) heat transport fluid. The microstructure of the tubes consists of elongated α‐Zr grains surrounded by a network of β‐Zr with a composition of approximately Zr‐20 wt% Nb. During operation an oxide layer is formed on the inside surface of the pressure tube where it is exposed to the D2O at 300ºC. A simple diffusion model for hydrogen ingress into the pressure tubes requires the hydrogen diffusion constants in the oxide layer as well as the hydrogen concentrations at the coolant/oxide interface and at the oxide/metal interface. Hydrogen diffusion in oxides has been studied by hydrogen implantation and 15N hydrogen depth profiling techniques. The studies have shown that microstructure and microchemistry of the underlying alloy can affect the characteristics of the oxide and in turn the transport of hydrogen through the oxide and into the underlying metal. In certain cases the oxide layer can be a homogeneous medium for hydrogen diffusion, but in most cases it is found to be heterogeneous and comprised of homogeneous, nonporous and fully oxidized, cells surrounded by a network of fast diffusion paths for hydrogen. Since in such heterogeneous systems the derived diffusion parameter and the cell size are interdependent, an absolute diffusion parameter could only be derived if the cell size were known. However, no such information is available from the microstructural studies on the oxides grown on these alloys. Another alternative is to carry out the measurements in a material, which would be homogeneous at least within the dimensions of a few μm ‐ the range of the measurements. With in mind, the hydrogen diffusion this measurements has been carried out in a set of single crystal zirconia specimens with the prospect that the single crystals would provide a non‐porous and homogeneous medium to study the diffusivity of hydrogen. The results from the single crystal zirconia specimens will be discussed. ®CANDU–CANada Deuterium Uranium is a registered trademark of Atomic Energy of Canada Ltd. ……………… DSL310 Prof. Pawel Dluzewski Computational Materials Science Group, Institute of Fundamental Technological Research PAS, ´Swie¸tokrzyska 21, 00‐049 Warsaw, poland
Indium Clustering in InGaN/GaN Quantum Wells: Thermodynamics and Finite Element Modelling Paweł Dłu˙zewski and Grzegorz Jurczak Computational Materials Science Group, Institute of Fundamental Technological Research PAS, ´Swie¸tokrzyska 21, 00‐049 Warsaw, PL We consider the interdiffusion in the samples used in experimental investigation in the High Resolution Transmission Electron Microscopy (HRTEM) [1]. Thermodynamic foundations based on the field theory is presented in brief [2]. The driving forces for interdifussion and mass transfer are derived from the balance equations. Two components are analysed: (1) the residual stress gradient and (2) gradient of chemical potential. Both components are analysed quantitatively. The mathematical foundations for a 3D FE modelling of the initial‐boundary‐value problem are presented. We consider a coupled problem for residual stresses and indium segregation. The process is simulated step‐by‐step in time including two concurrent components of the driving force. The chemo‐ mechanical initial‐boundary‐value problem is solved for: the nodal displacements and indium fraction spanned respectively on different subgroups (64/27) of 83 node finite element. In this way a self‐compatible formulation for different tensor fields operating in the same FE is obtained. The computer animation predicts to which resultant shape and position the clustering can tend to. [1] P. Ruterana, S. Kret, A.Vivet, G. Maciejewski and P. Dłu˙zewski, J. Appl. Phys. 91, 8979 (2002). [2] P. Dłu˙zewski, Defect and Diffusion Forum 264, 63 (2007).
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……………… DSL370 Prof. Panayota Vassiliou National Technical University of Athens, Heroon Polytechniou 9, 15780, Zografou, Greece
Electroless Ni‐P Composites with ZrO2: Preparation, Characterization, Thermal Treatment Jelica Novakovic, M. Delagrammatikas, P. Vassiliou and C.T.Dervos National Technical University of Athens, Athens, 15780, Greece The study of composite electroless Ni‐P coatings is pursued in order to obtain metal coatings on metal alloys with advanced properties i.e. with high wear and corrosion resistance for particular engineering and industrial uses. Many studies are produced where the properties of these coatings are of interest in electronics, in specific engineering applications on many types of substrates, i.e. metal or ceramic [1]. In the present work composite NiP‐ZrO2 layers were prepared by simultaneous electroless deposition of Ni‐P and ZrO2 on steel substrate, from a reductive solution in which ZrO2 particles were kept in suspension by stirring. The addition of zirconia particles in the bath leads to the simultaneous deposition of the particles with the Ni‐P alloy as it was previously observed for Ni‐P‐TiO2 composite coatings [2, 3]. The deposits are microcrystalline and poreless, therefore they have an increased corrosion resistance. Deposits were characterized for its structure, morphology and hardness by optical microscopy, scanning electron microscopy and microanalysis as well as X‐ray diffraction. The produced deposits were of 30 mm of thickness on cylindrical steel specimens. The load of the particles in the bath was 0, 0.5, 1, 2 and 5 g/l. It was found that the maximum ZrO2 particle incorporation attained was 7‐10% of Zr. Under the optical microscope the Vickers microhardness was measured for the plain deposit and found to be 720 HV and for the maximum zirconia content of 10%, 820 HV. After heat treatment under vacuum, for 10 min, the microhardness of the composite is found to be 1500 HV. The electrochemical measurement of linear polarization, in a corrosive NaCl 3.5% solution shows that the particles presence does not significantly influence s the corrosion resistance. [1] G.G. Gawrilov, ‘Chemical (Electroless) Nickel Plating’, Portcullis Press, Surrey, UK (1979) [2] J. Novakovic, P. Vassiliou, Kl. Samara, Th. Argyropoulos, Surface & Coatings Technology, Vol. 201 (2006) pp.895 901 [3] J. Novakovic and P. Vassiliou, Electrochomica Acta, Vol. 54 (2009) pp. 2499 ‐ 2503 ……………… DSL387 Mr. Philippe Garcia CEA, DEN, DEC, St‐Paul‐Lez‐Durance Cedex, 13108, France
Oxygen Diffusion in Relation to P‐Type Doping in Uranium Dioxide P. Garcia1, M. Fraczkiewicz1, C. Davoisne1,3, G. Carlot1, B. Pasquet1, G. Baldinozzi2, D. Siméone2 1CEA, DEN, DEC, St‐Paul‐Lez‐Durance Cedex, 13108, FRANCE. 2Matériaux fonctionnels pour l'énergie, équipe mixte CEA‐CNRS‐ECP, Gif‐Sur‐Yvette, 91191, FRANCE 3Imperial College, Materials Department, London, South Kensington, SW7 2AZ UK Thermally or radiation induced transport properties impact practically all engineering aspects of nuclear oxide fuels, whether at the manufacturing stage, during in‐reactor operation, or under long‐term repository conditions. From a more fundamental standpoint, measuring transport properties is also a means of probing point or complex defects that are responsible for atomic migration. Although many studies relating to oxygen diffusion in UO2 have been carried out in the past forty years, none has ever focussed on characterising this property as a function of all the physical variables which determine it, i.e. temperature and composition; the latter variable being determined, depending upon the temperature range investigated, by the equilibrium oxygen partial pressure and the concentration of bi‐ or tri‐valent impurities inevitably present on the cation sublattice. DSL‐2009 / Rome ‐ ITALY ABSTRACT BOOK
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In this paper we show how electrical conductivity and intrinsic oxygen diffusion coefficient measurements can be used in conjunction to further our understanding of oxygen related point defects in UO2. From electrical conductivity measurements performed on two types of samples containing very different doping levels, we show the positive charge carrier concentrations to be determined by the impurity concentration in the temperature range studied. The gas‐solid isotopic exchange method is then used to load the material with 18O tracer atoms and 18O concentration profiles are then characterised using SIMS. At the oxygen potential and temperature studied (750°C), the results point to oxygen migration proceeding via an interstitial mechanism and to the fact that impurities control point defect concentrations responsible for atomic migration ……………… DSL029 Dr. Mehrdad Abbasi Engineering Faculty, Material Science Dep., Islamic Azad University karaj branch, Karaj, Iran
Interface Intermetallic Growth Investigation of Annealed Cold Welded Al/Cu Bimetal M. Abbasi 1 1Engineering Faculty, Material Science Dep., Islamic Azad University karaj branch, Karaj, Iran;
[email protected] The aim of this article is to study the growth rate of Intermetallic compounds at interface of cold roll bonded Al/Cu bimetal at 250 oC and compare the results with a similar study performed on friction welding of Al to Cu. Samples of tri‐layered Cu‐Al‐ Cu composite were produced by cold roll welding process and annealed at constant temperature of 250 oC for 1 to 1000 hours. The thickness, morphology and composition of intermetallic compound at interface of Cu and Al were studied by optical and scanning electron microscopes and EDX analyzer. The presence of various intermetallic compounds (Cu3Al, Cu2Al, CuAl and CuAl2) was detected and the priority of formation of each compound was studied. For a binary system of Al‐Cu and a diffusion‐controlled process the interfce composition from copper side has to change from low to high Al‐content without a decrease in between. But EDX analyzer reviled that there is amid layer with a decrease Al‐content in between. This is proposed due to mixed chemical and diffusion controlled of growth process. The bond strength and electrical resistivity of different samples were measured by peeling test and a high precision micro‐ohmmeter, respectively. The variations of resistivity and bond strength versus thickness of intermetallic compound were plotted. It was observed that the strength and electrical conductivity is noticeably reduced by increasing the thickness of intermetallic compounds. Moreover, the growth rate of intermetallic compounds in roll welded bimetal composite is lower compared with that reported for similar friction welded specimens. Keywords: Aluminum; copper; roll welding; Intermetallic growth; diffusion controlled; bond strength; bimetal resistivity. ……………… DSL080 Mr. Luckman Muhmood Graduate Student, Royal Institute of Technology, Stockholm ‐10044, Sweden
Evaluating the Diffusion Coefficient of Sulphur in CaO‐SiO2‐Al2O3‐FeO Slag L. Muhmood1, T. Matshusita2 and S.Seetharaman3 1 Graduate Student, Royal Institute of Technology, Stockholm ‐10044, Sweden 2 Associate Professor, Royal Institute of Technology, Stockholm ‐10044, Sweden 3 Professor, Royal Institute of Technology, Stockholm ‐10044, Sweden The diffusion coefficient of sulphur in 35%CaO‐10%SiO2‐50%Al2O3‐5%FeO slag was determined at 1450°C using an iron crucible. Silver was used as the metal phase due to its low liquid solubility in iron, while a gas mixture of Ar‐CO‐CO2‐SO2 was allowed to react with the slag‐metal equilibrium system after maintaining it for 2 hours. The concentration of sulphur in the
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metal, slag and gas mixture at 14500C was determined by using Thermocalc and Thermoslag software. The metal and slag were kept in a specially designed crucible so as to avoid any slag entrapment during sampling. Metal samples were taken at regular intervals and chemically analyzed for sulphur. Using the mass balance equations, an equation was derived to evaluate the diffusion coefficient of sulphur in slag as a function of the sulphur content in silver at any time t. The results are discussed in the light of earlier diffusivity measurements by different techniques [1, 2]. References: 1. T. Saitô and Y. Kawai, Sci. Rep. RITU, A5 (1953), 460. 2. G.. Derge, W.O. Philbrook and K.M. Goldman, Tr. AIME, 188 (1950), 1111. ……………… DSL104 Prof. Peter Hing Physics Department Faculty of Science University of Brunei Darussalam Jaln Tunku Link BE Gadong BE1410, Negara Brunei Darussalam
Ultra Rapid Sintering of Ceramics P Hing Physics Department Faculty of Science University of Brunei Darussalam Jaln Tunku Link BE Gadong BE1410 Negara Brunei Darussalam Sintering of alumina to translucency was first reported by R L Coble [1]. Since then the sintering of translucent sintered alumina has been widely studied [2‐ 4]. The application of sintered alumina in high pressure sodium and more recently in ceramic metal lamps is also well documented [5‐ 7]. The sintering of alumina by conventional method requires prolonged sintering in hydrogen atmosphere. This is a very costly operation in terms of energy used, and the huge amount of hydrogen needed for the process. This paper presents for the first time investigations on the sintering of tubular alumina ceramics to translucency in a low thermal mass furnace. It is found that extremely fast sintering occurs in a foming gas atmosphere. Rapid densification occurs in minutes rather than hours in conventional sintering of ceramics. The relationship between processing, properties, microstuctures and performance are presented and discussed. References 1. R L Coble, British Patent No 3,026,210, 1961 2. R J Brook, Sci.. Met., 2 (7), 375, 1968 3. P Hing, Vacuum Sintering of Alumina to Translucency” British Ceramic Proceedings, Novel Synthesis and Processing of Ceramics, Edited by F. Resale, No. 53, 145‐168. 1995. 4. Yet ‐ Ming Chiang, D Birnie and W D Gingery, Physical Ceramics, Wiley‐MIT Chapter 5, Microstructure, 414‐418,1997. 5. M A Cayless and AM Marsden, Editors, Lamps and Lighting, Edward Arnold, Chapter 7, Lamp Materials, D T Evans and J Day, 123‐138, 1983. 6. P Hing, Processing, Properties and Performance of Sintered Aluminas, 6th International Conference on Materials Processing for Properties and Performance, Midas Symposium, September, 2007, Beijing, PRC. 7. P.Hing, Materials for Discharge Light Sources, Scientia Bruneiana, Volume 8/9, 81‐101, 2008. ……………… DSL384 Prof. Ho‐Soon Yang Pusan Center, Korea Basic Science Institute, Pusan 618‐230, Korea
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Improvement of the Electrochemical Properties in Nano‐Sized AlF3 and Al2O3‐Coated LiFePO4 Cathode Materials C. W. Ahn1, K. S. Hong1, E. D. Jeong1, D. J. Lee2, C. H. Doh2, K. Y. Doh3, J. M. Na3, B. H. Song3, H. M. Jeon3, Y. G. Cho3, and H. S. Yang4 1Pusan Center, Korea Basic Science Institute, Pusan 618‐230, Korea 2Korea Electrotechnology Research Institute, Changwon 641‐120, Korea 3Gyeongnam Science High School, Jinju 660‐851, Korea 4Department of Physics, Pusan National University, Pusan 609‐735, Korea LiFePO4 is one of the most promising cathode materials for Li ion batteries. However, the main obstacles in obtaining the theoretical performances of LiFePO4 are its low electrical conductivity and the difficulty in synthesizing single‐phase LiFePO4 because of the easy oxidation of Fe2+. We have tried several methods to improve the electric capacity of LiFePO4. For examples, we added organic materials such as humic acid and chitosan, and transition metals. Also we tried to synthesize LiFePO4 with different processes such as sol‐gel and solid‐state reaction methods. In this presentation, we describe the obtained results by adding aluminums in LiFePO4. The surface conditions of LiFePO4 powder were modified by adding AlF3 and Al2O3 by using the sol‐gel process to improve its electrochemical properties. The nano‐sized AlF3 and Al2O3 partially covered the surface of LiFePO4 powders, confirmed from an transmission electron microscope image. The state of coated Al materials was examined by using X‐ray photoelectron spectrometer results. The nano‐sized AlF3 and Al2O3‐coated LiFePO4 powders showed no difference in the bulk structure compared with the pristine one. However, the AlF3 and Al2O3 coating on LiFePO4 powder improved the overall electrochemical properties such as the cyclability and the rate capability compared with those of the pristine LiFePO4. Specially, the Al2O3‐coated LiFePO4 powder shows relatively high discharge capacity and good cycling stability. Its discharge capacity was 148 mAh/g at the 0.2 C rate and the capacity retention was about 93 % of its initial papacity after 50 cycles under 0.2 C rate. Such enhancements were attributed to the presence of the stable AlF3 and Al2O3 layer which acts as the interfacial stabilizer on the surface of LiFePO4. ……………… DSL399 Dr. Wolfgang Gruber TU Clausthal, Robert‐Koch_Str. 42, D‐38678 Clausthal‐Zellerfeld, Germany
Substrate Dependent Diffusion and Crystallization in Magnetron Sputtered SiC Films W. Gruber1, U. Geckle2, M. Bruns2, H. Schmidt1 1TU Clausthal, Robert‐Koch_Str. 42, D‐38678 Clausthal‐Zellerfeld, Germany. 2 Institut für Instrumentelle Analytik, Forschungszentrum Karlsruhe GmbH, D‐76344 Eggenstein‐Leopoldshafen, Germany. Thin films of amorphous and polycrystalline SiC have a great potential for applications in various branches of technology. For a tailored production of polycrystalline films an understanding of nucleation and growth mechanisms which determine the microstructure are necessary. X‐ray diffractometry (XRD) and transmission electron microscopy (TEM) studies on r.f. co‐ sputtered SiC films deposited on crystalline silicon and glassy carbon, respectively, yielded a three dimensional interface controlled growth mechanism from pre‐existing nuclei for both types of substrates [1]. However, the rates of crystallization strongly depend on the substrate. For single crystalline silicon as a substrate an activation enthalpy of about 4 eV is found for the rate of crystallization. If glassy carbon is used as a substrate the corresponding activation enthalpy is about 9 eV. For a closer investigation of this phenomenon, in this study we investigated films deposited on different substrates with different thickness (100 nm to 1 mm) and variable composition SiCx. Crystallization kinetics is investigated using grazing incidence X‐ray diffractometry (GIXRD). Since self‐diffusion plays an important role for crystallization we measured the diffusivities of the constituting elements for SiC films deposited on crystalline silicon and glassy carbon substrates, respectively. For diffusion measurements we used isotope enriched hetero structures produced via magnetron sputtering. For depth profiling secondary ion mass spectrometry (SIMS) was used. Based on the experimental results a model for crystallization kinetics is discussed. [1] H. Schmidt, E. R. Fotsing, G. Borchardt, R. Chassagnon, S. Chevalier and M. Bruns, Applied Surface Science, 252 (2005) 1460.
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……………… DSL247 Dr. Evgeniy Selivanov Institute of Metallurgy of Ural Division of Russian Academy of Sciences, 101, Amundsen Str., Yekaterinburg, 620016, Russia
Phase Formation in FeOx‐SiO2‐Cu2O‐ZnO‐FeS System During Melts Crystallization E.N. Selivanov, R.I. Gulyaeva, N.I. Selmenskich, L.Y. Udoeva Institute of Metallurgy of Ural Division of Russian Academy of Sciences, 101, Amundsen Str., Yekaterinburg, 620016, Russia The phase formation in oxide‐sulphidic systems was studied with use of thermodynamic modeling, X‐rays diffraction, mineralography, combined thermogravimetry and calorimetry, and also the x‐ray spectral microanalysis. The purpose of this work was to estimate effect of cooling rate of melts in FeOx‐SiO2‐Cu2O‐ZnO‐FeS systems on structure and content of the resulting phases. Test subjects were two samples having following compositions (wt. %): I ‐ 40.5 Fe, 2.41 S, 0.87 Cu, 3.87 Zn, 32.1 SiO2 and II ‐ 40.67 Fe, 3.05 S, 8.55 Cu, 4.05 Zn, 19.53 SiO2. Cooling rate of the milts was changed from 0.3 up to 900 K/s. Intensity of radiographic reflexes for phase components of the samples changes with cooling rate and amorphous structures appear at 900 K/s. Temperatures and heats of divitrification, ‘cold’ crystallization and melting of the tempering samples were determined. The phases formed at melt cooling are basically presented by magnetite and iron silicates with variable composition. Copper makes bornite solid solutions independently of crystallization rate. Zinc‐containing sulphidic phases are formed at slow cooling of the samples as well as at their annealing about 1000 K. Findings of investigation of nonferrous metals mass transfer and phases formations during oxide‐sulphidic melts crystallization can be used for improvement of valuable components extraction from slags for metallurgy of nonferrous metalls. This work was supported by the Russian Foundation for Basie Research, project no 07‐03‐96087 ……………… VIP‐DSL012 Prof. A. Fishman Institute of Metallurgy of the Ural Branch of Russian Academy of Sciences, RUSSIA
The Structural Phase Transitions in Mechanoactivated Manganese Oxides A.Ya.Fishman1, E.A.Pastukhov1, S.A. Petrova1, N.K. Tkachev2, R.G. Zakharov1 1Institute of Metallurgy, UD RAS, Ekaterinburg, 620016, Russia 2Institute of High Temperature Electrochemistry UD RAS, Ekaterinburg, 620041, Russia An attempt to obtain mechanochemically the nanoscaled manganese oxides (II, III) with certain structural characteristics has been undertaken, and an influence of conditions of mechanical processing on these characteristics has been investigated. Processing both single‐phase oxides and their mixes depending on time, structure of gas atmosphere, a chemical compound of investigated substance (mix), and process parameters was considered. As initial chemically pure manganese oxides Mn2O3, Mn3O4 and also mixes Mn2O3 ‐ Mn3O4 and Mn2O3 ‐ MnO2 taken in equimolar ratio were used. At that the ground attention was directed on the phase transitions from cooperative Jahn‐Teller (JT) state to low or high temperature phases. The size of particles of the received powders was estimated by means of laser analyzer HORIBA LA‐950 and a scanning electronic microscope. The phase composition of the substances obtained, the size of coherent scattering domains, as well as microstrains were defined by XRD. A surface of the oxides has been investigated by XPES and STEM methods. Exposed specific features of the structural phase transitions in nano‐sized oxide crystals were interpreted using the Kanamori model for JT crystal subsystem taking into account the size of nano‐crystallites, the distribution of cations over non‐equivalent sublattices, and random crystal fields. It was established right after a unique mechanochemical processing the sizes of grains decrease in hundreds times leading to mosaic blocks with the linear sizes of 10‐100 nm, rather free from any structural defects. Within these nondestructive grains
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in the course of the further intensive grinding changes of the sizes of coherent scattering domains and microstrains take place together with different chemical processes. Microstrains appeared at once after the first processing do not essentially vary throughout all process of grinding. Non‐monotonic dependence of the size of coherent scattering domains on processing duration is found out. It is shown the transaction of the Mn3O4 oxide to nanocrystalline state is accompanied by essential change of parameters of the Jahn‐Teller structural phase transformation. ……………… DSL130 Mr. Sébastien CHAUFFAILLE Université Bordeaux 1, Laboratoire de Mécanique Physique (LMP)‐UMR CNRS 5469, 351 Cours de la Libération, 33405 TALENCE Cedex, FRANCE
Liquid Diffusion in Polymers by Impedance Measurement S.Chauffaille, O. Devos, J. Jumel, M.E.R.Shanahan Université Bordeaux 1, Laboratoire de Mécanique Physique (LMP)‐UMR CNRS 5469, 351 Cours de la Libération, 33405 TALENCE Cedex, FRANCE. Despite the many advantages of polymeric materials in industry, medicine, civil engineering, etc., polymers are to some extent permeable to fluids [1]. This can be a major problem in the case of polymeric adhesives in, for example, the aircraft industry. Classically, liquid diffusion in polymers is studied by gravimetry. This technique is relatively straightforward when using bulk polymer samples. In the case of adhesive joints, the procedure is difficult to employ, since the relative mass of polymer compared to the substrates is generally small, thus considerably reducing the precision, although a method to estimate diffusion rates from mechanical properties has been suggested [2]. Here we propose an electrochemical technique. The adhesive layer constitutes part of an (alternating, AC) electrical circuit, also containing in series a metallic substrate (adherend) and water, in contact with the polymer. Impedance, but particularly capacitance, varies with water uptake into the adhesive, following diffusion. At high frequency, the impedance is essentially due to a capacitive contribution. Using a classic model [3] to estimate the volume fraction of water content from changes in permittivity, it is possible to estimate overall liquid uptake and the corresponding coefficient of diffusion. Results compared to those found by gravimetry suggest that this technique could be developed as a useful tool for monitoring diffusion and permeation. Not only is the method continuous in time, but also avoids disturbing the system during the diffusion process. [1] P. Neogi, Ed., Diffusion in Polymers, Plastics Engineering Series, Vol. 32 (Marcel Dekker, New York, 1996). [2] M.P. Zanni‐Deffarges and M.E.R. Shanahan, Inter. J. Adhesion Adhesives, 15, 137 (1995). [3] D.M.Brasher and A.H. Kinsbury, J. Appl. Chem., 4, 62 (1954). ……………… DSL351.1 Mr. Dong‐Wan Department of Applied Chemistry, KonKuk University, Chungju, Chungbuk, Korea
Preparation and Characteristics of Silicon Grafted Poly(ethersulfone)s D. W. Seo1, D. G. Kim1, Y. D. Lim1, S. H. Lee1, S. H. Moon2, S. C. Ur3, T. W. Hong3, and W. G. Kim1 1Department of Applied Chemistry, KonKuk University, Chungju, Chungbuk, Korea 2Department of Animal Science, Konkuk University, Chungju, Chungbuk, Korea 3Department of Materials Science and Engineering, Chungju National University, Chungju, Chungbuk, Korea Propenyl contained poly(ethersulfone)s were prepared with bisphenol A, 3,3’‐diallyl‐4,4’‐dihydroxy‐biphenyl and 4‐ fluorophenylsulfone, respectively, at 160Ԩ using potassium carbonate in N,N’‐dimethylacetamide. The silicon grafted poly(ethersulfone)s were prepared from the propenyl contained polymer precursor and one H‐functional siloxane. The syntheses of silicon grafted polymers were achieved by hydrosilylation with platinum (0)‐1, 3‐divinyl‐1, 1, 3, 3‐
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tetramethyldisiloxane complex solution as catalyst. The properties of resulting polymers such as structural characteristics, thermal properties, surface morphologies were investigated by 1H NMR spectroscopy, DSC, TGA, and AFM. Grafting of silicone made a remarkable change to the poly (ethersulfone) polymer. The silicon polymers possess some interesting properties such as low surface energy, water repellency and bioinertness. ……………… DSL079 Prof. Koichi Terasaka Keio University, Yokohama, 223‐8522, Japan
Mass Transfer from Shrinking Single Microbubble into Electrolytic Aqueous Solution 1
2
2
1
K. Terasaka , M. Okubo , Y. Sato , D. Kobayashi 1
2
Keio University, Yokohama, 223‐8522, Japan.
Graduate School of Keio University, Yokohama, 223‐8522, Japan.
The smaller bubble than ca.100 μm is called “microbubble.” The microbubbles have very large specific surface area and very slow rising velocity. The microbubbles dissolve so fast into liquid and adsorb particles so well that microbubble aeration came to be utilized in marine industry, agriculture and lake purification in Japan. Moreover, the industrial applications of microbubble such as gas absorber, flotation and particle recovery are also investigated because the microbubble technology contributes to the reduction of additives, high efficiency and high recovery. On the other hand, Terasaka [1] discovered that a crystal generates on a microbubble when the single microbubble is shrinking in dilute NaCl aqueous solution as shown in Fig. 1. To form a crystal in solution, generally, the solute concentration has to be excess supersaturated concentration. When a static single microbubble is rapidly dissolving into electrolytic aqueous solution, however, the dissolved gas component let the supersaturation of electrolyte at the microbubble surface reduce. Therefore, a solid crystal was produced on the shrunk microbubble due to salting out by the gas dissolution. The crystallization in dilute solution can be applied for the industrial crystal seed production and the other useful purposes. In this study, the microbubble shrinkage in some electrolytic aqueous solutions was observed using a digital microscopic video camera. The mechanism of mass transfer from a shrinking microbubble was proposed. The shrinkage behaviour was simulated with a theoretical model.
Gas: dry oxygen Liquid:0.1wt%NaCl aq. soln
.
Fig.1 Crystallization during micro bubble shrinkage [1] K. Terasaka, Japanese Patent Application, 2007‐307851 (2007). ……………… DSL169 Dr. Kang‐Sup Chung Korea Institute of Geoscience and Mineral Resources, Korea
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Lithium Metal Phosphates as Cathode Materials for Li‐ion Batteries: Analysis and First‐principles Calculation Kang‐Sup Chung1, Jae‐Chun Lee1, Hwan Lee1, Hee‐Jin Kim2, Yang‐Soo Kim2 1Korea Institute of Geoscience and Mineral Resources, Korea. 2Korea Basic Science Institute, Korea. We studied the possibility of using the metal oxide powders as cathode active materials for lithium ion batteries, and found out their electrochemical performance and principles through the calculation. We report the novel lithium metal phosphates which can be used as potential cathode materials in terms of practical applications such as average voltage and reaction mechanism. We characterized crystal and electronic structures of lithium metal phosphates using TGA, XRD, XPS, SEM, and TEM. We studied the electrochemical properties using the first‐principles calculation. In analyzing the electronic structure and chemical bonding of the lithium metal phosphates, we used two kinds of first‐principles calculations: molecular orbital calculations using the DV‐Xα method and the ab initio total‐energy and molecular dynamics program VASP. [1] Adachi H, Tsukada M and Satoko C, J. Phys. Soc. Jpn. 45 875(1978). [2] Tarascon J. M and Armond M, Nature 414 359(2001). [3] Averill F. W and Ellis D. E, J. Chem. Phys. 59 6412(1973). ……………… DSL255 Dr. Aleksandr Micko Riga Technical University, Riga, 14 Azenes Str., LV‐1048, Latvia
Graded Band‐gap Structure Formation in CdZnTe due to Redistribution of Cd and Zn Atoms and Quantum Confinement Effect A.Medvid’1,2, A.Mychko1, V.Gnatyuk2, S.Levytskyi2and Yu. Naseka2 1Riga Technical University, Riga, 14 Azenes Str., LV‐1048, Latvia 2Institute of Semiconductor Physics, prospect Nauki, 41, Kyiv, 03028, Ukraine. The aim of this research is to show the possibility of graded band‐gap structure [1] formation in Cd1‐xZnxTe sample using the second harmonic of a Q‐switched Nd: YAG laser radiation (LR). The sample Cd1‐xZnxTe/SiO2 crystals were irradiated at a room temperature and atmospheric pressure by a second harmonic (l = 532 nm, t=15ns) of the Nd: YAG laser at intensities from 0, 2 MW/cm2 to 12 MW/cm2. Photoluminescence (PL), atomic force microscope (AFM) and photoconductivity (PC) were used as the main investigation tools. After irradiation of Cd1‐xZnxTe crystal at laser intensity more than 0.2 MW/cm2 the exciton line A0X of PL spectra shifted to a lower energy ‐“red shift” and at laser intensity I=2MW/cm2 it had a maximal value of 4,1meV. Nanohills formed on the surface of the semiconductor crystal after irradiation by laser with intensity of I ≈ 4 MW/cm2, caused PL spectrum shift in the direction of high energy – “blue shift”. The shift of A0X line at laser intensity of I =12 MW/сm2 was DE=7.7meV. The shifts of exciton A0X line are explained by Exciton quantum confinement effect in nanostructures formed on the surface of the semiconductor. The graded band‐gap structure with optical window is formed on the peaks of nanohills. At laser intensities less than 4 MW/cm2 the maximum of PC band shifted to the lower quantum energy – “red shift”, but at higher intensities the “blue shift” takes place. This result is in a good agreement with PL measurement data. The possibility of graded band‐gap formation in Cd1‐xZnxTe crystal by the second harmonic of Nd: YAG laser radiation has been revealed. The Thermogradient effect plays the main role in the redistribution of Zn atoms [2] at the irradiated surface of Cd1‐xZnxTe at laser intensities from 0.2 MW/сm2 till 2 MW/сm2. [1] V.F Kovalenko, G.P. Peka, L.G. Shepel’Phys.Tech. of Semicon. V.14, 1350 (1980) [2] A.Medvid’ Defects and Diffusion Forum, 89, 210‐212 (2002). ……………… DSL270 Dr. Adam Barcz
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Institute of Electronics Technology, Institute of Physics PAS Al. Lotnikow 32/46, 02‐668 Warsaw, Poland
Silicon Dioxide as a Boundary for Oxygen Outdiffusion from CZ‐Si Adam Barcz Institute of Electronics Technology, Institute of Physics PAS Al. Lotnikow 32/46, 02‐668 Warsaw, Poland It is well evidenced that heating a Czochralski‐grown silicon supersaturated with oxygen to concentrations [O] ~1018/cm3 leads to oxygen outdiffusion and formation of a so‐called “denuded zone”. Most authors used to consider the resultant concentration that develops at the surface, Csurf(out), as synonymous with the solid solubility of oxygen Cs [1]. We have argued that, rather, the correct measure of Cs is a surface concentration that develops upon in‐diffusion of oxygen into a float zone Si [2]. We established Cs = Csurf(in) by measuring in‐depth profiles using SIMS technique with so far unattainable detectability 2000
x •
E=hυ
x •
Fig.1. Fig.2. - Fe3O4( 15°, σGBmin usually corresponds to the twin GBs. For φ > 15° a GB is a continuous two‐dimensional defect. Below φ = 15° a GB is discontinuous and consists of a set (a wall or a network) of lattice dislocations. Its energy σLow can be below σGBmin and respective wetting transition temperature TwLow > Twmax. We observed such phenomenon for the first time in the Cu–Ag system. Above TwLow, the Ag‐rich melt penetrates into the network of the low‐angle Cu subgrains.As a result, the Cu‐grains disintegrate into small particles. GB triple joints (TJ) can also be wetted by a liquid. In this case the TJ is substituted by the triangular prism filled by a liquid. The wetting condition for TJ (σGB > (σSL)0.5) is weaker that that for a GB (σGB > 2σSL). As a result, the wetting transition temperature for TJs TwTJ is below the minimal wetting
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transition temperature for GBs TwTJ DGa. However, the difference in the diffusion coefficients of both constituent elements is different between Ni3Ge and Ni3Ga. It is suggested that α‐sublattice vacancy mechanism is operative in L12 –type intermetallic compounds. For L10‐type structure such as γ‐TiAl, significant diffusion anisotropy is observed. The diffusion of Ti in the diffusion perpendicular to the [001] axis is almost one order of magnitude faster than that parallel to the [001] direction. Such diffusion anisotropy is similar to that of In diffusion. It is suggested that Ti atoms diffuse on the Ti sublattice, while Al(In) atoms also diffuse on the Ti sublattice. The cause of the anisotropy of the diffusion coefficient is discussed in view of the defect structure and the correlation of the jump vectors of successive vacancy jumps.
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……………… DSL136 Dr. Robert Filipek Faculty of Materials Science and Ceramics, Interdisciplinary Centre of Materials Modeling, AGH University of Science and Technology, Al. Mickiewicza 30, 30‐059 Kraków, Poland
Diffusion‐Reaction Mechanism and Kinetics of the Intermetallics Growth ‐ Theory and Experiment R. Filipek Faculty of Materials Science and Ceramics, Interdisciplinary Centre of Materials Modeling, AGH University of Science and Technology, Al. Mickiewicza 30, 30‐059 Kraków, Poland Diffusion soldering technology is an effective method of obtaining stable metal/metal interconnections using solder which forms intermetallic phase with the joining materials. The joint microstructure, chemical composition and the sequence of appearance of the intermetallic phases are important factors that influence its stability. The important parameters determining diffusion soldering technology are thickness of solder, time and temperature of the process. Understanding of the mechanism of this process is necessary for prediction of growth kinetics of phases and finally optimisation of the diffusion soldering technology. The phenomenological model enabling a description of the growth of intermetallic phases in multi‐component systems is presented. Full time‐dynamics approach is applied without often used simplifications such as flux constancy. General form of the species flux is considered which consists of chemical potential gradient as a driving force for diffusion with additional drift term. Stefan‐type (moving) boundary conditions are considered. The concept of flux constraint allows estimating a delay of the formation of the slowly growing phases. In the present form the model assumes local equilibrium at each interface and that the process of growth of intermediate phases is controlled by diffusion of reagents through the layers and/or chemical reactions at the boundaries. The model is solved in its full generality. Numerical method for the solution to the problem has been developed. First, by specially selected change of dependent variables the moving boundary problem was transformed into an equivalent fixed boundary problem. Next, such problem was treated using the method of lines which converts partial differential equations into system of ordinary differential equations (ODE) which is effectively solved. Due to the large number of the ODEs to be solved the solution of the model was obtained using a parallel computing technique. Calculations have been performed on the computer cluster using shared and distributed memory models utilizing OpenMP and MPI standards. Numerically obtained solution was tested and compared with analytical solution available in special cases and other approximate solutions (e.g., enthalpy and Murray‐Landis methods) showing satisfactory agreement. The presented model was used for modelling of growth of intermetallic phases in binary Ag/Sn, Ag/In and ternary Cu/In‐Sn systems and compared with experimental results. The problem of determination of diffusion coefficients in multi‐component multi‐layer systems is discussed. ……………… DSL133 Dr. Andriy Gusak Cherkasy National University, 81 Shevchenko blvd., Cherkasy, Ukraine
IMC Growth and Competition in Nano‐scale Reactions A.M.Gusak, T.V.Zaporozhets, S.V.Kornienko
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Cherkasy National University, 81 Shevchenko blvd., Cherkasy, Ukraine Initial stages of intermetallic compound formation and growth will be reviewed. Among others, the following new topics will be discussed: 1. Reconsideration of Goesele‐Tu model for initial IMC growth stages for the case of strong composition dependence of interdiffusivity inside growing phase. (Interface kinetics leads to change of boundary concentrations with time, and, in case of strong concentration dependence, it leads to change of averaged diffusivity. Thus, effective diffusivity depends on phase thickness, and this dependence can be monotonous as well as non‐monotonous) 2. Effect of finite efficiency of vacancy sinks/sources in the bulk and at the moving interfaces of intermetallic layer on the growth kinetics. (Difference of partial diffusivities within IMC leads to vacancy fluxes, and limited efficiency of vacancy sinks/sources leads to additional vacancy gradients changing the fluxes of main components. Process is governed by, at least, 3 characteristic lengths) 3. Synergy of interface barriers, nonequilibrium vacancies and passing electric current in the IMC competition. (Criteria of phase suppression/growth are presented for various DC regimes) 4. Compounds growth and competition in hollow nano‐shell formation – interplay of Kirkendal, inverse Kirkendall, Frenkel and Gibbs‐Thomson effects. (Kinetic models of single‐phase and two‐phase growth in core‐shell structures are presented.) 5. IMC competition during SHS in multilayered foils. (Phenomenological steady‐state model and general mesoscopic model of multiphase SHS are presented for case of one‐by one and case of simultaneous IMC formation) ……………… VIP‐DSL006 Prof. I. Belova The University of Newcastle, AUSTRALIA
Origin of the Vacancy‐Wind Effect in Interdiffusion in Intermetallics I.V. Belova1, G.E. Murch1 1University of Newcastle, Callaghan, NSW, 2308, Australia. The vacancy‐wind effect is a subtle phenomenon that occurs when two atomic species compete for vacancies in a net vacancy flux. The vacancy‐wind effect is embodied in (for example) the vacancy‐wind factor that appears in the Darken‐Manning Equation relating the interdiffusivity, the tracer diffusivities and the thermodynamic factor. The vacancy‐wind factor is nearly always calculated by building it up from its components of tracer and collective correlation factors. Accordingly, the actual physics behind the vacancy‐wind phenomenon have not been well understood. Recently, a moving reference frame Monte Carlo method was used to graphically illustrate how the vacancy‐wind effect operates in both ionic conductivity in an ionic solid with impurities and chemical interdiffusion in a concentrated alloy [1]. Those ideas are extended in this paper to show graphically how the vacancy‐wind effect operates in interdiffusion in an intermetallic taking the B2 structure. A simple 4‐frequency vacancy diffusion model was used. In previous work, it was shown that depending on composition and temperature, this model can exhibit both six‐jump‐cycle and antistructural bridge mechanisms. [1] I.V. Belova and G.E. Murch, Defect and Diffusion Forum, Vol. 273‐276, (2008), pp431‐444. ……………… VIP‐DSL031 Prof. Helmut Mehrer
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Institut für Materialphysik, Universität Münster, 73635 Obersteinenberg, Berghof, Germany
Invited Talk Diffusion in Intermetallics Helmut MEHRER Institut für Materialphysik, Universität Münster, Wilhelm‐Klemm‐Str. 10, 48149 Münster, Germany now: 73635 Obersteinenberg, Berghof, Germany e‐mail: mehrer@uni‐muenster.de Diffusion in solids is fundamental in the art and science of materials and an important topic of solid‐state physics, physical metallurgy and materials science. A deeper knowledge about diffusion requires information on the positions of atoms and how they move in solids. In crystalline solids the atomistic mechanisms of diffusion are closely connected with defects. Point defects often mediate diffusion. Dislocations and grain boundaries are other types of defects and can act as high‐diffusivity paths, because the mobility of atoms along such defects is usually much higher than in the lattice. Intermetallics are compounds of two metals or of a metal and a semimetal. Their structures are different from those of the constituents. Some intermetallics are interesting functional materials others have attracted attention as high‐temperature structural materials. The talk reviews some results on bjunary intermetallics mainly from our laboratory including the systems Fe‐Al, Fe3Si, FeSi, NiMn, TiAl and Mo2Si. Literature: H. Mehrer, Diffusion in Solids — Fundamentals, Methods, Materials, Diffusion.controlled Processes, Springer‐ Verlag, July 2007 Textbook H. Mehrer, S. Divinski, Diffusion in Metallic Elements and Intermetallics, Defect and Diffusion Forum, in print ……………… DSL236 Prof. Lyudmila Paritskaya Department of Crystal Physics, Karazin National University, Kharkov 61077, Ukraine
Intermetallic Growth: Structure‐Sensitive Effects L. N. Paritskaya1, Yu. Kaganovskii2, V. V. Bogdanov1 1Department of Crystal Physics, Karazin National University, Kharkov 61077, Ukraine; 2Department of Physics, Bar‐Ilan University, Ramat‐Gan 52900, Israel. We discuss the role of different structural defects, such as non‐stoihiometric vacancies, pores, free surfaces and grain boundaries (GBs) in kinetics of intermetallic growth. The main objects of our studies were the systems Ni‐Cd, Cu‐Cd, and Cu‐Sn. Bulk intermetallic growth. The “dynamic” diffusion coefficients measured experimentally from the kinetics of intermetallic growth on the base of our theoretical analysis turn out much higher compared to tracer diffusion coefficients in stable intermetallics, whereas the activation energies are about twice lower. This result is caused by deviation of growing phases from stoichiometry and we discuss possible diffusion mechanisms involving non‐ stoihiometric vacancies. In the systems with “unipolar” phase growth the directed vacancy flux leads to interfacial pore formation, which hinders and even prevents the phase growth. We show that relatively low compressive pressures (of the order of
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Laplace pressure) suppress interfacial pore formation and provide non‐prohibited intermetallic growth. Lateral intermetallic spreading over a free surface. We have found that propagation of intermetallic phases along a free surface occurs several times faster than in the bulk. We have developed a theory of the surface phase growth that allows calculation of the “dynamic” diffusion coefficients over the surface of growing phases from the kinetics of surface phase spreading. Lateral intermetallic propagation along GBs in nano‐grained thin films. The rate of phase propagation in nano‐ grained thin films exceeds 5‐10 times the phase spreading rate over the free surface in coarse‐grained samples and 50‐70 times exceeds the bulk growth rate. It was found that the accelerated phase growth is caused by diffusion through GB nano‐network and it is rather sensitive to the grain size: the smaller grain size the higher the rate. The theoretical analysis of the phase propagation kinetics, accelerated by GB diffusion has been done. It allows calculating the dynamic GB diffusion coefficients in the growing phases. ……………… DSL181 Mr. Hiroaki Fukaya Department of Materials, Physics and Energy Engineering, Graduate School of Engineering, Nagoya University, Nagoya 464‐8603, Japan
Diffusion of Ti, V, Nb in Ni3Al at Elevated Temperatures H. Fukaya1, Y. Murata1, M. Morinaga1, T. Koyama2, W. Hashimoto3, K. Tanaka3 and H. Inui3 1Department of Materials, Physics and Energy Engineering, Graduate School of Engineering, Nagoya University, Nagoya 464‐8603, Japan 2National Institute for Materials Science (NIMS), Tsukuba 305‐0047, Japan 3 Department of Materials Science and Engineering, Graduate School of Engineering, Kyoto University, Kyoto Diffusion of Al replacing elements in the γ’ phase (Ni3Al) is important for considering the properties of Ni‐based superalloys, which are strengthened by the γ’ phase. Ni3Al consists of four sublattices based on f.c.c. lattice. Three sublattices of them are occupied by Ni atoms and the other one is occupied by Al atom in the stoichiometric Ni3Al. As a result, a Ni site is surrounded by 8 Ni sites and 4Al sites as the nearest neighbor sites, while an Al site is surrounded by 12 nearest neighbor Ni sites. So, the diffusion of alloying elements as the solute in the γ’ phase depends strongly on their substitution behaviors in Ni3Al lattice. In this study, interdiffusion coefficients of Al replacing elements in Ni‐Al‐X (X=Ti,V,Nb) were estimated by a series of experiments using diffusion couples of Al rich pseudo‐binary systems at three different temperatures of 1423, 1473 and 1523K. In order to obtain interdiffusion coefficients of the pseudo‐binary systems, the experimental data was analyzed by Saucer and Freise method, and also impurity diffusion coefficients of Ti, V and Nb in Ni3Al were estimated by applying the Darken‐Manning equation. The magnitude of interdiffusion coefficient decreased in order of V, Ti and Nb at all three temperatures. Impurity diffusion coefficients were described by the expressions: D 4.4 10 1 exp( 422kJ / RT ) Ti = × − − , D 5.3 10 2 exp( 387KJ / RT ) V = × − − , D 2.1 101 exp( 479kJ / RT ) Nb = × − . The activation enthalpies obtained from the experimental data confirmed the retardation of Ti, V and Nb diffusion in Ni3Al by the anti‐site diffusion mechanism. These results are consistent with our previous work on diffusion of Re and Ru in the Ni3Al [2]. [1] A.F. Giamei and D.L. Anton: Metall. Trans. 16A (1985) 1997‐2005. [2] E. Mabruri, S. Sakurai, Y. Murata, T. Koyama and M. Morinaga: Mater. Trans. 49 (2008) 1441‐1445. ………………
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DSL301 Prof. F. M. da Conceição Viana Faculty of Engineering, University of Porto, Portugal
Interdiffusion in Ni/Al nanometric multilayers F. Viana 1, S. Simões 1, A. Sofia Ramos2, M.T. Vieira2 and M.F. Vieira1 1CEMUC, Department of Metallurgical and Materials Engineering, University of Porto, R. Dr. Roberto Frias, 4200‐465 Porto, Portugal 2CEMUC, Department of Mechanical Engineering, University of Coimbra, R. Luís Reis Santos, 3030‐788 Coimbra, Portugal Self‐propagating exothermic reactions occurs in multilayer films with alternating layers of a transition metal and a light element. These systems are very attractive to applications such as brazing or solid‐state diffusion bonding due to the high velocity of these reactions associated with high heat release rate. Ni/Al multilayer films were deposited by dc magnetron sputtering from pure nickel and aluminium targets. Films with period of 5, 14 and 30 nm were produced. The asdeposited films are constituted by alternate nickel and aluminium layers that upon thermal annealing diffuse and react with each other to form intermetallic compounds. For a particular system, the heat evolved during the solid state reactions occurring in the nanometric multilayer thin films depends on the atomic diffusion distance (the layer thickness) and interdiffusion at the layers interface. Interdiffusion is known to occur during deposition with the consequent formation of chemically diffuse interfaces. Interdiffusion in as‐deposited films was investigated by high resolution transmission electron microscopy (HRTEM). HRTEM observations reveal that intermixing of Ni and Al atoms occurred during deposition of the films, promoting the formation of NiAl in small areas. NiAl formation during deposition is more significant in smaller period thin films and, as a result, the heat evolved by the solid state reaction is also smaller. This work was supported by “Fundação para a Ciência e a Tecnologia” through the project PTDC/CTM/69645/2006 and the Grant SFRH/BD/30371/2006 financed by POS_C. ……………… DSL389 Dr. Ana Sofia Figueira Ramos Departamento de Engenharia Mecânica Faculdade de Ciências e Tecnologia da Universidade de Coimbra R. Luís Reis Santos 3030‐788 Coimbra, PORTUGAL VAT 502971142 Reaction‐Assisted Solid State Diffusion Bonding A.S. Ramos1, M.T. Vieira1, S. Simões2, F. Viana2, M.F. Vieira2 1CEMUC®, Department of Mechanical Engineering, University of Coimbra, R. Luís Reis Santos 3030‐788 Coimbra, Portugal. 2CEMUC®, Department of Metallurgical and Materials Engineering, University of Oporto, R. Dr.Roberto Frias, 4200‐465 Porto, Portugal. The introduction of reactive multilayer thin films as interlayer material seems to offer a promising method for similar and dissimilar joining of intermetallics and superalloys. In order to assist in the bonding process the parts to be joined are coated with reactive multilayer thin films made up of alternating nanolayers. Multilayer thin films with nanometric bilayer thickness (period) increase the diffusivity and reactivity at the joint interface.
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g‐TiAl based intermetallics and Ni based superalloys were coated by magnetron sputtering with a few microns thick Ni/Al reactive multilayer thin films with different modulation periods (5, 14 and 30 nm). Diffusion within the layered structure is promoted during heating and the multilayer thin films react to form intermetallic compounds with nanometric grain size which should guarantee the thermal and mechanical resistance of the joint. Solid state diffusion bonding was performed in vacuum at 700 and 800ºC under 5 MPa after stacking the coated materials with the films’ surface facing each other. The deposition of Ni/Al reactive multilayer thin films onto the base material allowed the diffusion bonding process to be carried out at relatively low temperature. Both Al and Ni took part in the reaction and, after diffusion bonding there is no sign of the original layered structure. Sound joining without cracks or pores is achieved, especially when a 14 nm period Ni/Al film is used as interlayer material. During the diffusion bonding experiments interdiffusion and reaction inside the Ni/Al multilayer thin film and between the interlayer film and the base materials is promoted with the formation of intermetallic phases. From the TiAl side to the superalloy side the joint’s interface is composed of: diffusion layer I, diffusion layer II, reacted interlayer thin film, bond line, reacted interlayer thin film, diffusion layer III and diffusion layer IV. In order to help in the identification of the different layers composing the joint, nanoindentation experiments were carried out along a perpendicular to the bond line. ……………… VIP‐DSL071 Dr. Giovanni Mazzolai University of Perugia, Italy
Hydrogen Diffusion Coefficient in the Disordered and Ordered Pd3Mn Compound as Deduced from High Temperature Hydrogen Absorption Measurements Giovanni Mazzolai 1,2 1University of Perugia, Department of Physics, Via A. Pascoli 5, 06123 Perugia,Italy 2Telematic University e‐Campus, Via Isimbardi 10, 22060 Novedrate (CO),Italy. The Hydrogen absorption kinetics has been investigated by the gas‐solid reaction method in two bar shaped samples of the Pd3Mn compound, which is known to undergo an order‐disorder transition when heated up above about 800 K [1]. One of the sample, quenched from high temperature, was in a disordered state, the other, which had been very slowly cooled from 1123 K down to room temperature, had an ordered L12 structure. With the disordered sample the measurements were carried out from 825 K up to 1038 K; with the second from about 485 K to 666 K. The data on the rate of H absorption, which were analyzed according to the second Fick’s equation, provided for the diffusion coefficient of H values exhibiting an exponential temperature dependence. The diffusion coefficient, in agreement with previous lower temperature data obtained by Gorsky relaxation [2] was higher in the disordered than in the ordered state. This observation is accountable for in terms of the different kinds of jumps that H can make between adjacent interstitial octahedral sites in the two different states of order. As a matter of fact, in the disordered state, H long‐range diffusion takes place preferentially through I6‐I6 and I6‐I5 jumps (sub index indicating the number of Pd atoms located in the shell of the nearest neighbors of an octahedral interstitial site I), while in the ordered state the involved jumps are between adjacent I4‐I4 and I6‐I4 octahedral sites. [1] T. B. Flanagan, A. P. Craft, T. Kuji, K. Baba and Y. Sakamoto, Scripta Metall., 20, 1745 (1986). [2] B. Sobha, B. Coluzzi, F. M. Mazzolai, T. B. Flanagan and Y. Sakamoto, J. Less‐Common Metals, 172‐174, 254 (1991). ………………
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DSL203 Dr. Aloke Paul Department of Materials Engineering Indian Institute of Science, Bangalore – 560012
Study on the Growth of Nb3Sn Superconductor in (Cu‐Sn)/Nb Diffusion Couple A.K. Kumar1, T. Laurila2, V. Vuorinen2, A. Paul1* 1. Department of Materials Engineering and Centre for Electronics Design and Technology, Indian Institute of Science, Bangalore – 560012 2. Electronics Integration and Reliability, Department of Electronics, Helsinki University of Technology, FIN ‐02015 TKK, Finland Nb3Sn growth following the bronze technique that is by interdiffusion between (Cu‐Sn) bronze alloy and Nb is one of the important methodologies to produce the superconductor. The confusion over the growth rate is addressed. Furthermore, a possible explanation for the corrugated structure of the product phase in the multifilamentary structure is discussed. Kirkendall marker experiments are conducted to study the relative mobilities of the species, which also explains the reason for finding pores in the product phase layer. The movement of the markers after interdiffusion reflects that Sn is the faster diffusing species. Furthermore, different concentrations of Sn in the bronze alloy are considered to study the effect of Sn content on the growth rate. Based on the parabolic growth constant at different temperatures, the activation energy for the growth is determined. We have further explained the dramatic increase in the growth rate of the product phase by changing just one atomic percentage of Sn in the Cu‐Sn bronze alloy. Following, it was shown that the diffusion of Cu and Nb through the product phase is impossible since atoms cannot diffuse against its chemical potential gradient. ……………… DSL032 Dr. German Anibal R. Castro Instituto Politécnico Nacional. SEPI‐ESIME U.P Adolfo López Mateos, Zacatenco México D.F. 07738 México
Effect of Boriding in the Mechanical Mroperties of AISI 1045 Steel G. Rodríguez‐Castro 1, I. Campos‐Silva 1 J. Martínez‐Trinidad 1, U. Figueroa‐López 2, D. Meléndez‐Morales 3, J. Vargas‐Hernández 3 1 Instituto Politécnico Nacional. SEPI‐ESIME U.P Adolfo López Mateos, Zacatenco México D.F. 07738 México. 2 Tecnológico de Monterrey Campus Estados de México, Carretera al Lago de Guadalupe, km. 3.5, Atizapán Edo. de México 52926, México 3 Instituto Politécnico Nacional. SEPI‐ESIQIE U.P Adolfo López Mateos, Zacatenco México D.F. 07738 México. Some mechanical properties of AISI 1045 borided steels were estimated in the present work. The boriding process was carried out by the powder pack method at 1223 K with 8 h of treatment. The fatigue strength on borided notched specimens was evaluated with rotating bending tests (R=1) considering a stress concentration factor (Kt) of 2.53. Likewise, the presence of residual stresses in boride layers was established by the XRD technique. The Daimler‐Benz Rockwell C test was used, also, to estimate the strength adhesion of the coated system. The results show a decrease in the fatigue strength of AISI borided steels due to the presence of high porosity in the layers and the influence of tension residual stresses at the surface of the samples. Finally, the Rockwell‐C adhesion test showed no coating failure for the boride layer. ……………… DSL192
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Mr. Arijit Laik Materials Science Division, Bhabha Atomic Research Centre, Mumbai ‐ 400 085, India
Solid State Diffusion Properties of Zr–Al System A. Laik and K. Bhanumurthy Materials Science Division, Bhabha Atomic Research Centre, Mumbai–400085, India. E‐mail:
[email protected] Zirconium based aluminides and their alloys are being proposed for use as structural materials in nuclear reactors due to their low neutron absorption cross–section, corrosion resistance in aqueous medium, adequate mechanical properties and irradiation stability. Therefore the study of diffusion behaviour in these alloys becomes very important. Reactive diffusion in the Zr–Al system has been studied in the temperature range of 833K to 898K using Zr/Al bulk diffusion couples prepared using pre‐annealed pure Zr and Al pieces. The intermetallic phases formed at the Zr/Al interface was characterised using electron probe microanalyser (EPMA). ZrAl3 was found to form as the major phase in the interdiffusion zone in all the couples. Zr2Al3 was also found to form, along with, in the diffusion zone at and above 873K. Due to large difference in diffusion rate between Al and Zr, the Kirkendall pores formed during the process of interdiffusion, got accumulated at the ZrAl3/Al interface. The integrated interdiffusion coefficient [1,2] for ZrAl3 and Zr2Al3 and the average interdiffusion coefficient for ZrAl3 were determined using the concentration profiles across the diffusion zone, acquired by point‐to‐point quantitative analysis using EPMA. The variation in activity of Al across the intermetallic compounds in the diffusion zone was plotted using the thermodynamic properties of the concerned phases of the Zr‐Al system. Thermodynamic interdiffusion coefficients, based on the chemical potential gradient, [3] for both the phases were also determined. The temperature dependence of the diffusion coefficients evaluated was in accordance with Arrhenius relationship. The activation energy for interdiffusion for the ZrAl3 was estimated to be 182.6 kJ/mol and 184.6 kJ/mol for average interdiffsion coefficient and thermodynamic interdiffusion coefficients respectively. [1] M. A. Dayananda, Metallurgical and materials Transactions, 27A, 2504, (1996). [2] C. Wagner Acta Metall., 17, 99, (1969). [3] S. P. Garg, G. B. Kale, R. V. Patil and T. Kundu, Intermetallics, 7, 901, (1999). ……………… DSL381 Dr. Mangelinck Institut Matériaux Microéléctronique Nanosciences de Provence, IM2NP‐CNRS (UMR 6242), Case 142, Faculté de Saint‐Jérôme, F‐13397 Marseille Cedex, France
Formation of Ni, Pd and Pt Silicides: Determination of Interfacial Mobility and Interdiffusion Coefficient by in‐situ Techniques, Role of Stress D. Mangelinck, K. Hoummada, C. Perrin 1 Institut Matériaux Microéléctronique Nanosciences de Provence, IM2NP‐CNRS (UMR 6242), Case 142, Faculté de Saint‐Jérôme, F‐13397 Marseille Cedex, France The kinetics of formation of the first phases obtained by reaction of nanometric metal thin film with silicon substrate has been investigated. A method [1] has been developed to measure differential scanning calorimetry of a thin film on a substrate and was applied to study the silicide formation. In combination with in‐situ and real time X ray diffraction experiments, these measurements have allowed to determine the kinetics of silicide formation. The interface mobililities and the interdiffusion coefficients for Ni2Si, Pt2Si and Pd2Si have been determined by
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using a model [2] taken into account the nucleation and lateral growth as well as a normal growth controlled by diffusion and interface reaction. A comparison of these kinetic parameters for the different silicides will be discussed. This first determination of the interface mobilities gives some insights for the role of interface in the silicide formation. Another important parameter for the silicide formation is the stress. Indeed in‐situ and real time X ray diffraction experiments have shown that stress influence the silicide formation: the transformation of Ni2Si in NiSi has been found to depend on the stress relaxation in Ni2Si [3]. [1] Hoummada K., Portavoce A., Perrin‐Pellegrino C., Mangelinck D., and Bergman C., Appl. Phys. Lett. Vol. 92, art. 133109, 2008 [2] K. R. Coffey, L. A. Clevenger, K. Barmak, D. A. Rudman and C. V. Thompson, Appl. Phys. Lett. 55, 852 (1989). [3] D. Mangelinck and K. Hoummada, Appl. Phys. Lett. 92, 254101 (2008). ……………… DSL413 Mrs. Alexandra Ioannidou University of Western Macedonia, Kozani, GR50100, Greece
Influence of Additions in the Composite Mg2Ni/M (where M=TiB2 or V) Metal Hydrides A. Ioannidou1, S. S. Makridis1, E. Michailidou1, E. S. Kikkinides1 and A. K. Stubos2 1University of Western Macedonia, Kozani, GR50100, Greece 2National Centre of Scientific Research, Athens, GR 15 310, Greece Metal hydrides have the potential for reversible on‐board hydrogen storage and release at low temperatures and pressures. They began with the negative electrode of Ni–MH (metal hydride) batteries in 1990 and with fuel cells (FC) that were developed especially for the emission‐free vehicles. According to the data so far, the hydride alloys are mostly in the AB2‐type Ti‐ or Zr‐ based alloys and in the AB5‐type of compounds for relatively low temperature applications. High temperature metal hydrides are based in Mg alloys. The largest challenge today may be to find hydrogen storage solutions. In this research work, Metal hydrides based on Mg, have the advantage of safe hydrogen’s transfer under small pressure (~1 bar). Projects running lately on Mg‐based alloys because Mg is a promising material due to the large hydrogen capacity (up to 7.6 wt %), low cost and non toxicity. Ball milling/mechanical alloying technique is one of the most suitable synthetic methods to prepare Mg‐based alloys. Mg has high vapor pressures below its melting point, which makes preparation by melting method very difficult. In this research work, have been developed nanocomposite materials based on Mg2Ni/M (where M=TiB2 or V). The materials have been produced after 40 h of milling under vacuum by using a high energy planetary ball miller. The crystal structure and microstructural properties of the samples have been studied by using an x‐ray diffractometer, having a Cu‐Kα radiation, and a scanning electron microscopy, respectively. Hydrogen activation has been performed on the as milled samples for 3 hours at 300 oC while discharging properties have been investigated by using a Sievert‐type volumetric apparatus. ……………… DSL513 Mr. Seyed Abdolkarim Sajjadi Faculty of Materials Science and Metallurgical Engineering. Sahand University of Technology, Tabriz, Iran
Processing of Nanocrystalline Ni3Al Powder Using mechanical alloying technique
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M. Abbasi1, S. A. Sajjadi2, M. Azadbeh1 1Faculty of Materials Science and Metallurgical Engineering. Sahand University of Technology, Tabriz, Iran 2Department of Materials Science and Metallurgical Engineering, Engineering Faculty, Ferdowsi University of Mashhad, Mashhad, Iran The intermetallic compound Ni3Al with unique properties is widely used especially for high temperature applications. There are different ways for producing the compound. One of them is high‐energy milling technique using a planetary ball mill which has been employed for producing nanocrystalline powders. In this research Ni3Al intermetallic was prepared by mixing of pure elemental powders. A ball‐to‐powder weight ratio of 20:1 and rotation rate of 550 rpm in argon atmosphere were the main processing parameters. The milling time ranged from 1 to 55 hours. Changes in phase and microstructure as a function of milling time were investigated, using X‐ray diffraction analysis and scanning electron microscopy. The results showed that at the early stages of milling, diffraction peaks are sharp. During mechanical alloying the sharp peaks of as received powder are broadened progressively with increasing processing time associated with accumulated internal strain and refinement of grain size. In the mean while the intensity of peaks were lowered with mechanical alloying time. After 10 hours of milling, Ni3Al peak could be observed but the exact result was at 15 hours. SEM study of the powder at the milling time of 15 h confirmed homogeneity of the powder. The results revealed that formation of Ni3Al nanocrystallites occurred after 15 hours milling, and minimum crystallite size was 5 nm at that time. Key words: intermetallics, mechanical alloying, nanostructured materials, X‐ray diffraction. ……………… VIP‐DSL020 Prof. Y. Sohn University of Central Florida, USA
Site Preference and Diffusion in Ni3Al Alloyed with Ir, Ta or Re at 1200°C N. Garimella, Y.H. Sohn Advanced Materials Processing and Analysis Center Department of Mechanical, Materials and Aerospace Engineering University of Central Florida, Orlando, FL, USA Diffusion in L12‐Ni3Al with ternary alloying additions of Ir, Ta and Re was investigated at 1200°C using solid‐to‐solid diffusion couples, and examined with respect to site preference in ordered intermetallic compound. In addition to determination of average ternary interdiffusion coefficients [1, 2], average effective interdiffusion coefficients were determined directly from the experimental concentration profiles. Ni has the largest magnitude of average effective interdiffusion coefficient, followed by Al, Ir, Re and Ta. The average effective interdiffusion coefficients for Ir, Re and Ta are much smaller than those for Ni and Al. Tracer diffusion coefficients determined by extrapolation technique, and available literature also followed the same trend. The relative tendency of Ni, Al, Ir, Re and Ta to occupy the α‐Ni and β‐Al sites are correlated to these diffusion coefficients, with due consideration for diffusion mechanisms as well as the size and coordination of atoms. [1] N. Garimella, M. Ikeda, M. Ode, H. Mukarami, Y.H. Sohn, Intermetallics, 16, 1095, (2008). [2] N. Garimella, M. Ikeda, M. Ode, H. Mukarami, Y.H. Sohn, Journal of Phase Equilibria and Diffusion, in Press, 2009. ……………… DSL206
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Dr. R. Ravi Department of Materials Engineering Indian Institute of Science Bangalore ‐560012, India
Diffusion Studies in A3B Compound with A15 Structure R. Ravi, A.K. Kumar and A. Paul Department of Materials Engineering, Indian Institute of Science, Bangalore – 560012 Intermetallic compounds with A15 structure draw special attention because of superconductor application. There is a constant effort to understand the defect structure and diffusion behavior in this structure. Diffusion of elements depends mainly on the structural defects, antisites and vacancies on different sublattices. In this article, we shall discuss diffusion of elements in different compounds. It is predicted that Nb should be much faster diffusing species compared to Sn in the Nb3Sn compound. Further development lacks because of unavailability of data in binary Nb‐Sn system. However, indeed majority element is found to be much faster in V3Si and V3Ga compounds. On the other hand, significant diffusion rate is found in Ti3Au phase. It reflects the presence of different structural defects in different compounds. ……………… DSL022 Dr. Iman Farahbakhsh
The Role of Diffusion on Catalyst Design for Dehydrogenation of Di‐Ethyl Benzene M. E. Zeynali1, I. Soltani 1, 2 1‐ Petrochemical Faculty,Iran Polymer and Petrochemical Institute P.O. Box: 14965/115. Tehran, I. R. Iran 2‐ Chemical Engineering Group, Research &Development Center, Iran Khodro CO. P.O. Box: 13895/111. Tehran, I. R. Iran
[email protected] [email protected] The dehydrogenation of diethylbenzene to divinylbenzene is a catalytic reaction. The catalyst of the dehydrogenation was prepared by coprecipitation of iron and chromium hydroxide from nitrates solution followed by doping with potassium carbonate, and drying. For availability the internal surface area of the catalyst for reactant the pores must be in proper sizes to allow the reactant to diffuse and penetrate inside the catalyst pellets. The prepared catalyst was considered as a model to investigate the role of diffusion in catalyst design. In this study different mechanisms of diffusion such as Knudsen and bulk were investigated for diethylbenzene diffusion into catalyst and it was concluded that the pore sizes should be in the range that permit transitional diffusion (both Knudsen and bulk diffusion). The catalyst grain size can be controlled and varied by different parameters such as speed and time of mixing, type of alkali, temperature and pH. Particle size distribution experiments were conducted for different type of alkali and speed of mixing to characterize the catalyst. The effects of grain size formed during coprecipitation on pore size distribution of the catalyst pellet which affect the effective diffusivity were discussed. Pore size distribution of the model catalyst was obtained and the effective diffusivities were calculated by numerical integration of Johanson‐Stewart equation. Keywords: pore size distribution, diffusion, catalyst, coprecipitation
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References 1‐ Chen, S., Sun, A., Qin, Z., and Wang, J., “Reaction coupling of diethylbenzene dehydrogenation with water‐gas shift over alumina‐supported iron oxide catalysts”, Catalysis communications, 4 (9), 441 (2003). 2‐ Joseph, Y., Wuhn, M., Niklewski, A., Ranke, W., Weiss, W., Woll, C., and Schlogl, R., “Interaction of ethylbenzene and styrene with iron oxide model catalyst film at low converges: A NEXAFS study”, Phys. Chem.. chem.. phys., 2, 5314 (2000). 3‐ Ye, X., Yue, Y., Miao, C., Xie, Z., Hua, W., and Gao, Z., “Effect of modifiers on the activity of a Cr2O3/Al2O3 catalyst in the dehydrogenation of ethylbenzene with CO2”, Green Chem., 7, 524 (2005). 4‐ Schule, A., Shekhah, O., Ranke, W., Schlogl, R., and Kolios, G., “Microkinetic modeling of dehydrogenation of ethylbenzene to styrene over unpromoted iron oxide”, Journal of catalysis, 231, 172 (2005). 5‐ Mimura, N., Saito, M., “Dehydrogenation of ethylbenzene to styrene over Fe2O3/Al2O3 catalysts in the presence of carbon dioxide,” Catalysis today, 55, 173 (2000). 6‐ Matsui, J., Sodesawa, T., and Nozaki, F., “Activity decay of potassium‐promoted iron oxide catalyst for dehydrogenation of ethylbenzene”, Applied catalysis, 51, 203 (1989). 7‐ Saito, M., Kimura, H., Mimura, N., Wu, J., and Murata, K., “Dehydrogenation of ethylbenzene in the presence of CO2 over an alumina‐supported iron oxide catalyst”, Applied catalysis A: General, 239, 71 (2003). 8‐ Liu, W., “Multi‐scale catalyst design”, Chemical Engineering Science, 62, 3502 (2007). 9‐ Bensetiti, Z., Schweich, D., and Abreu, C.A.M., “The sensitivity of the catalyst effectiveness factor to pore size distribution,” Braz. J. Chem. Eng. 14 (3) (1997). 10‐ Mezedur, M. M., Kaviany, M., and Moore, W., “Effect of pore structure, randomness and size on effective mass diffusivity”, AIChE, 48 (1), 15 (2002). 11‐ Zalc, J. M., Reyes, S. C., and Iglesia, E., “Monte‐Carlo simulations of surface and gas phase diffusion in complex porous structure,” Chemical Engineering Science, 58, 4605 (2003). 12‐ Haynes, H. W., “The experimental evaluation of catalyst effective diffusivity”, Catal. Rev.‐Sci. Eng., 30 (4), 563 (1988). 13‐ Koci, P., Stepanek, F., Kobicek, M., and Marek, M., “Modelling of micro/nano‐scale concentration and temperature gradients in porous supported catalysts,” Chemical Engineering Science, 62, 5380 (2007). 14‐ Szczygiel J., “Diffusion and kinetics of reaction over bidispersive reforming catalyst,” Computers and chemistry, 24, 203 (2000). 15‐ Szczygiel, J., “Diffusion in bidispersive grain of a reforming catalyst”, Computers and chemistry, 23 (2), 121 (1999). 16‐ Szczygiel, J., “Enhancement of reforming efficiency by optimizing porous structure of reforming catalyst: Theoretical consideration,” Fuel, 85 (10), 1579 (2006). 17‐ Sahin, E., Dogu, T., and Mortezaoglu, K., “Thermal effects on effectiveness of catalyst having bidisperse pore size distributions”, Chemical Engineering Journal, 93 (2), 143 (2003). 18‐ Gheorghiu, S., and Coppens, M. O., “Optimal bimodal pore network for heterogeneous catalysis,” AIChE, Journal, 50 (4), 812 (2004). 19‐ Parachayawarakorn, S., Prakotmak, P., and Soponronnarit, S., “Effects of pore size distribution and pore‐ architecture assembly on drying characteristics of pore networks,” International Journal of heat and mass transfer, 51 (1‐2), 344 (2008). ……………… DSL137 Prof. Sofoklis S. Makridis University of Western Macedonia, Kozani, GR50100, Greece
Combined Structural and Electronic Analysis and the Effect of Substitutions on the LaNi5‐Type Compositions for Hydrogen Storage Approaches A.V. Oikonomou1, S. S. Makridis1, E. S. Kikkinides1 and A. K. Stubos2 1University of Western Macedonia, Kozani, GR50100, Greece
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2National Centre of Scientific Research, Athens, GR 15 310, Greece To use hydrogen as a major global energy carrier, there are several fundamental and technical problems to be solved. The largest challenge today may be to find hydrogen storage solutions. The compounds of LaNi5‐type are hydrogen storage alloys that can reversibly absorb and desorb hydrogen at room temperature. They can easily be activated as well as produce high reacting rate of absorbing and desorbing hydrogen. In order to improve sorption properties, either A or B in the intermetallic AB5 type of compounds are partially substituted by other elements in the simplest case. In this work, we examine the effect of substitution for AB5 type hydrogen storage alloys by placing Sm and Co in the sites of A and B, respectively. X‐ray theoretical diffraction has been used to analyze LaxSm1‐xNi5, LaxCe1‐xNi5, and La (NixCo1‐x)5 (x=0, 0.1,…1) stoichiometries having the CaCu5‐type of crystal structure. The effect of Sm substitution for La is clearer by taking the intensity difference of the calculated patterns. After the full replacement of the La in LaxSm1‐xNi5 composition, the intensity has been increased for the (011) plane around 10 % while the (111) plane has ~3 % higher intensity. Since knowledge of the electronic structure is of great importance for a better understanding of the structural details, being part of the hydrogenation process, the electronic properties of pure and hydrogenated compounds LaNi5, CeNi5, LaCo5, SmNi5, and their hydrides have been studied. The generalized gradient approximation (GGA) of PBE [1] is used for the exchange‐correlation functional. The Fermi energy (EF) slightly changes throughout hydrogenation while the density of states (DOS) graphs of the investigated systems are describing the number of states at each energy level that are available to be occupied. [1] J.P. Perdew, K. Burke and M. Ernzerhof Phys. Rev. Lett., 77, 3865 (1996)
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SPECIAL SESSION:
Characterization and Properties of Hard Coatings ORAGANISED BY: Prof. Dr. Iván E. Campos Silva IPN SEPI‐ESIME, MEXICO Prof. Dr. Ulises Figueroa López ITESM‐CEM, MEXICO VIP‐DSL060 Prof. Oronzio Manca Dipartimento di Ingegneria Aerospaziale e Meccanica, Seconda Universita' degli Studi di Napoli Real Casa dell'Annunziata, Via Roma 29, Aversa (CE) 81031, Italy
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Natural Convection in Vertical Channels with Porous Media and Adiabatic Extensions Bernardo Buonomo, Oronzio Manca, Sergio Nardini Dipartimento di Ingegneria Aerospaziale e Meccanica Seconda Università degli Studi di Napoli Aversa (CE), Italy
[email protected] Convective heat transfer in saturated porous media has received considerable attention during the past several decades because of its wide range of applications. An interesting problem is that of heat transfer in a vertical channel with two uniformly heated flat plates and adiabatic extentions. Numerical investigations can give useful information on the effects of the heat flux, the spacing and the adiabatic extensions length. In this paper, reference is made to natural convection in air in a vertical channel with porous media and the two principal flat plates at uniform heat flux with adiabatic extensions. The numerical analysis is carried out in laminar, two dimensional and steady state regime. The physical domain consists of two parallel plates which form a channel and the adiabatic extensions collinear to the heated walls. Both plates are heated at uniform heat flux. The imbalance between the temperature of the ambient air and the temperature of the heated plates draws a mass of fluid into the vertical channel. The fluid between the two plates is air. The study is carried out employing the Brinkman‐Forchheimer‐extended Darcy model in two dimensional. The flow in the channel is assumed to be two‐dimensional, laminar, incompressible. Boussinesq approximation is considered. The thermophysical properties of the fluid are evaluated at the ambient temperature (300 K). Results in terms of wall temperature profiles as a function of the adiabatic extensions, the heat flux and the channel spacing are presented. Mass flow rate, wall temperature and average Nusselt number are presented for different values of characteristic parameters. DSL092 Mr. Enrique Hernandez Sanchez Instituto Politécnico Nacional, Grupo Ingeniería de Superficies, U. P. Adolfo López Mateos, Zacatenco México D.F. 07738, México
Anistropy of Boride Layers: Effect in the Mechanical Properties of AISI 4140 Borided Steels I. Campos‐Silva, E. Hernández‐Sánchez, Y. Dávila‐Montaño, J. Hernández‐Lozada, J. López‐Islas, C. Santos‐Medina Instituto Politécnico Nacional, Grupo Ingeniería de Superficies, U. P. Adolfo López Mateos, Zacatenco México D.F. 07738, México. The growth of iron borides over the surface of different steels is of high anisotropy [1]. It was determined that the anisotropy of FeB and Fe2B phases reveals a significant instability of properties in service [2]. One of the techniques to determine the effect of anisotropy on the mechanical properties of iron borides is the induced‐ fracture by microindentation [3, 4]. During the present work, the microindentation fracture toughness (KC) of boride layer has been estimated at the surface of AISI 4140 borided steel.
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The force criterion of fracture toughness was determined from the extent of brittle cracks, both parallel and perpendicular to the surface, originating at the tips of an indenter impression. The indentation loads were established between 1.9 to 9.8 N at distances of 25 and 45 mm from the borided surface. The KC values were expressed as KC (π/2) ˃ KC (0). Likewise, the adherence of the coated system was evaluated by Rockwell‐C indentation, where the borided steel showed sufficient adhesion. [1] G. Wahl, Durferrit‐Technical Information. Reprint from VDI‐Z117 785 (1975). [2] A.V. Byakova, Poroshkovaya Metallurgiya 4 36 (1993). [3] G. Ramírez, I. Campos, A. Balankin, Mater. Sci. Forum 553 21 (2007). [4] I. Campos, R. Rosas, U. Figueroa, C. VillaVelázquez, A. Meneses, A. Guevara, Mater. Sci. Eng. A 475 285 (2008). ……………… VIP‐DSL009 Prof. I. E. Campos Silva IPN SEPI‐ESIME, Mexico
Properties and Characterization of Hard Coatings Obtained by Boriding: An Overview I. Campos‐Silva Instituto Politécnico Nacional, Grupo Ingeniería de Superficies, U. P. Adolfo López Mateos, Zacatenco México D.F. 07738, México. The properties and characterization of hard coatings obtained by the paste‐boriding process were performed in this work. The development of boride layers at the surface of different commercial steels were carried out in the temperature ranges of 1123 to 1273 K with exposure times of 2‐8 h, using boron carbide paste thicknesses between three to five millimeters over the material surface. Depending upon the steel grade, temperature, treatment time and boron carbide paste thickness, two types of layers can be created in the borided samples: a Fe2B monolayer or FeB/Fe2B bilayer, modifying the physical, mechanical and chemical properties at the material surface [1‐3]. Different techniques were used for the characterization of hard coatings such as optical microscopy, scanning electron microscopy (SEM), Glow Discharge Optical Emission Spectroscopy (GDOES), X‐Ray Diffraction (XRD), microindentation fracture toughness, measurement of residual stresses by XRD, Atomic Force Microscopy, corrosion resistance through linear polarization technique, adherence of the coated system by Rockwell‐C indentation and fractal geometry. These methods were performed to characterize the nature, morphology and adherence of the boride layers. [1] I. Campos, O. Bautista, G. Ramírez, M. Islas, J. de la Parra, L. Zuñiga, Appl. Surf. Sci. 243 429 (2005). [2] I. Campos, R. Rosas, U. Figueroa, C. VillaVelázquez, A. Meneses, A. Guevara, Mater. Sci. Eng. A 475 285 (2008). [3] I. Campos‐Silva, A. Balankin, A.H. Sierra, R. Escobar‐Galindo, N. López‐Perrusquia, D. Morales‐Matamoros, Appl. Surf. Sci. 255 2596 (2008). ……………… DSL065 Prof. Maurizio Vedani Politecnico di Milano Dipartimento di Meccanica Sezione Materiali per applicazioni meccaniche via La Masa 34, 20156 Milano
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Tel. 0223998638 Fax. 0223998282 Italy
Plasma Nitriding of Titanium and Titanium Alloys S.Farè1, N. Lecis1, M. Vedani1, G. Vimercati1 A. Silipigni2, D. Corti2, P.Favoino2 1Politecnico di Milano – Dipartimento di Meccanica, Via G. La Masa 34, 20156 Milano, Italy. 2TAG s.r.l. Via Marconi, 9 23843 Dolzago (Lc) Italy Titanium and its alloys are extremely interesting materials for engineering applications thanks to the combination of several properties, like high strength, high corrosion resistance and light weight. Nevertheless, disadvantages are still present when using titanium in applications that require high tribological properties (like in biotechnological and aerospace industry). These drawbacks can be avoided by exploiting surface treatment that enhance surface performance. Among surface treatment, plasma nitriding seems to be the most promising technique for industrial applications because it can form a very hard layer on the surface of the material. Several studies have been carried on and show that is possible to reach very high hardness value, up to 800‐1200 HV. Atmosphere of treatment, furthermore, seems to play a key role in this process. From literature, it is known that mainly atomic nitrogen is responsible for saturation of surface layers of titanium. To increase the concentration of atomic nitrogen, it is necessary to add inert gases like He and Ar, in order to promote dissociation of molecular nitrogen. In this work several process parameters are taken into account in plasma nitriding of titanium alloys. The nitriding atmosphere was investigated considering several gas mixture like argon and helium in different percentage with nitrogen. Another parameter considered was the nitriding time, ranging from a short treatment of 20 hours, up to 146 hours treatment. Samples of pure titanium and of Ti6Al4V alloy have been analyzed using GDOES technique (Glow discharge optical emission spectroscopy) to determine nitrogen concentration profile from the surface; microhardness and scratch testing were adopted to evaluate mechanical properties of the nitrided layers. Optical and scanning electron microscopy were used to characterize the structure of the samples. ……………… DSL151 Dr. Jose Martinez‐Trinidad Instituto Politécnico Nacional, Grupo Ingeniería de Superficies, U. P. Adolfo López Mateos, Zacatenco México D.F. 07738, México
Dependence Between the Boron Surface Concentration and the Growth kinetics of Boride Layers in AISI 4140 Steels M. Ortiz‐Domínguez, I. Campos‐Silva, J. Martínez‐Trinidad, M. Elías‐Espinosa, E. Hernández‐Sánchez, D. Bravo‐Bárcenas Instituto Politécnico Nacional, Grupo Ingeniería de Superficies, U. P. Adolfo López Mateos, Zacatenco México D.F. 07738, México. The present work estimates the growth kinetics of Fe2B layers formed at the surface of AISI 4140 steels. The thermochemical treatment was applied in order to produce the Fe2B phase, considering temperatures of 1123, 1173, 1223 and 1273 K with four exposure times (2, 4, 6, and 8 h), using a 4 mm layer thickness of boron carbide paste over the material surface.
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The growth of iron boride layers was described by the mass balance equation between phases in thermodynamical equilibrium, assuming that the boron concentration at the interfaces remains constant [1‐3]. The boron diffusion coefficient at the Fe2B ( ) and the mass gain at the surface of the borided steels were established as a function of treatment temperatures. Finally, a simple relationship was proposed to describe the evolution of the parabolic growth constant at the interface as a function of both temperature and boron surface concentration. [1] C.M. Brakman, A.W.J: Gommers, E.J. Mittemeijer, J. Mater. Res. 6 211 (1989). [2] I. Campos‐Silva, M. Ortíz‐Domínguez, C. VillaVelázquez, R. Escobar, N. López, Defect and Diffusion Forum 272 79 (2007). [3] I. Campos, J. Oseguera, U. Figueroa, J. A. García, O. Bautista, G. Kelemenis, Mater. Sci. Eng. A 352 261 (2003). ……………… DSL352 Prof. C. Choung‐Lii Department of Mechanical and Electro‐Mechanical Engineering, Tam‐Kang University, No.151 Ying‐Chuan Road, Tamsui, Taipei Hsien, Taiwan 251
Investigation of the Interfacial Reaction between Optical glasses and Various Protective Films and Mold Materials C.L. Chao1, C.B. Huo1, W.C. Chou1, T.S. Wu1, K.J. Ma2, Y.T. Chen3, C.W. Chao4 1Department of Mechanical and Electro‐Mechanical Engineering, Tam‐Kang University, No.151 Ying‐Chuan Road, Tamsui, Taipei Hsien, Taiwan 251 2Department of Mechanical Engineering, Chung Hua University, No. 707, Sec. 2, Wu Fu Rd., Hsin Chu, Taiwan 30067 3Department of Mechatronic, Energy and Aerospace Engineering, National Defense University, No. 190, Sanyuan 1st St., Tahsi, Taiwan 33508 4Department of Information Management, Hsing‐Wu College, Lin‐Ko, Taiwan Glass molding process(GMP) is regarded as a very promising technique for mass producing high precision optical components such as spherical/ aspheric glass lenses and free‐form optics. However, only a handful of materials can sustain the chemical reaction, mechanical stress and temperature involved in the glass molding process. Besides, almost all of these mold materials are classified as hard‐to‐machine materials. This makes the machining of these materials to sub‐micrometer form accuracy and nanometer surface finish a rather tough and expensive task. As a result, making mold life longer has become extremely critical in the GMP industry. The interfacial chemical reaction between optical glass and mold is normally the main reason for pre‐matured mold failure [1][2]. This research aimed to investigate the interfacial chemical reaction between various optical glasses, different anti stick coating designs and several mold materials. The results showed that glass composition, coating design (composition, microstructure, thickness...), environment (vacuum, air or in protective gas), reaction temperature and time could all have profound effects on the interfacial chemical reaction. Based on the results, a design developed specially for certain glasses is more likely to be the viable way of optimizing the effect of the protective coating. [1] A. Jain, G.C. Firestone, and A.Y. Yi, J. Am. Ceram., 88 [9], p.2409 (2005). [2] K.J. Ma, H.H. Chien, C.L. Chao and K.C. Hwang, Key Engineering Materials, Vols. 364‐366, p.655 (2008). ……………… DSL364 Prof. Ma Kung‐Jeng
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chool of Science and Engineering, Chung Hua University, No. 707, Sec. 2, Wu Fu Rd., Hsin Chu, Taiwan 30067
The Effect of TaN Interlayer on the Performance of Pt‐Ir Protective Coatings in Glass Molding Process Hsi‐Hsin Chien1, Kung‐Jeng Ma1, Jane‐Huang Kuo1, Zen Bong Huo2, Choung‐Lii Chao2, and Ying‐Tung Chen3 1School of Science and Engineering, Chung Hua University, No. 707, Sec. 2, Wu Fu Rd., Hsin Chu, Taiwan 30067. 2Department of Mechanical and Electro‐Mechanical Engineering, Tam‐Kang University, No.151 Ying‐Chuan Road, Tamsui, Taipei Hsien, Taiwan 251. 3Department of Mechatronic, Energy and Aerospace Engineering National Defense University Glass molding process provides a great potential for mass production of precise glass optical components at low cost. The key issue for achieving a low production cost is to extend the service life of the expensive mold inserts. The precious metal based alloy is one of the coating materials for the molds which provide excellent glass anti‐ sticking results. However, the inter‐diffusion between the WC/Co mold materials and precious metal coatings will deteriorate the coatings which need to be resolved. It is essentially to deposit an interlayer as the diffusion barrier to improve inter‐diffusion problem. A thin layer of TaN was deposited on the WC/Co substrate as the diffusion barrier using magnetron sputtering system, and followed by the deposition of Pt/Ir multilayer as the protective layer. Low Tg Glass gobs (L‐BAL 42) were placed on the coated substrate to investigate inter‐diffusion between the substrate and coating at high temperature. The surface interaction between the glass gobs and protective coatings was also examined. The obtained TaN film had dense nano‐crystalline structure with (110) preferred orientation. High temperature wetting tests showed that the TaN film could effectively resist the cobalt diffusion into the precious metal protective layer and, as a result, minimized the possibility of interaction between glass and protective coating. The coated substrates remained good surface finish and the glass gobs stayed fully transparent after 12 hours wetting test at 580oC. ……………… DSL031 Dr. Sujira Promnimit Naresuan University, Phitsanulok, 65000, Thailand
Thin Film Multilayers and its Properties by Self‐Organization of Nanoparticles S. Promnimit1 and J. Dutta2 1Naresuan University, Phitsanulok, 65000, Thailand. 2Asian Institute of Technology, Pathumtani, 12120, Thailand. In this work, we report multilayer thin film devices based on self‐organized colloidal nanoparticles through Layer‐ by‐Layer (LbL) technique [1]. Nanoparticles are self‐ organized into assemblies to create novel nanostructures is getting increasing research attention in microelectronics, medical, energy, and environmental applications. The nanoparticles are considered to be the building blocks for novel devices. Directed self‐organization of nanoparticles [2] into multilayer thin film was achieved through LbL growth through the interaction of charges of colloidal nanoparticles on any kinds and shapes substrate. Multilayer thin film devices were fabricated using multilayers of conducting (gold) nanoparticles separated by a dielectric nanoparticle (zinc sulphide). The obtained thin films have studied extensively and the surface morphology, changes in the optical absorption characteristics, thickness, uniformity, adhesion, and conduction behavior will be reported. Current voltage (I‐V) characteristics of multilayer devices with an increasing number of deposition cycles show an initial current blockade until an onset voltage value, which increases linearly upon the addition of the number of the layers stacked in devices [3]. A conductive behavior of the device could be observed after exceeding the onset
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voltage. Moreover, the current‐voltage behavior showed that the conduction onset voltage increases linearly depending on the numbers of layers in the final device controlled by the deposition cycles. Systematic I‐V characteristics in the forward and reverse biased conditions demonstrated rectifying behaviors in the onset of conduction voltage which makes these films attractive for future electronic devices. [1] R. K. Iler, J. Colloid Interf Sci., 21, 569 (1966). [2] J. Dutta and H. Hofmann, In Encyclopedia of nanoscience and Nanotechnology, H. S. Nalwa, Ed. American Scientific Publishers, 9, 617 (2004). [3] S. Promnimit, S.H.M. Jafri, D. Sweatman and J. Dutta, JNO., 3, 184 (2008). ……………… DSL037 Dr. Alfonso Meneses Amador Instituto Politécnico Nacional. SEPI‐ESIME U.P Adolfo López Mateos, acatenco México D.F. 07738 México. Residual stresses obtained in AISI 1018 borided steels A. Meneses‐Amador 1, I. Campos‐Silva 1, J. Martínez‐Trinidad 1, G. Rodríguez‐Castro1 1 Instituto Politécnico Nacional. SEPI‐ESIME U.P Adolfo López Mateos, Zacatenco México D.F. 07738 México. In this work, thermal residual stresses were evaluated at the surface of AISI 1018 borided steels. The treatment was developed by means of the boriding powder technique at temperatures of 1123, 1173 and 1223 K with exposure times of 4, 6 and 8 h. The residual stresses on the layers were measurement by the XRD technique using the “XSTRESS3000” equipment. The ψ tilt angles are fixed between ‐45° to +45° and the φ angles were established in 0 and 90°. The results show the presence of tension and compressive residual stresses on the surface of borided steels. Also, the magnitude and the behavior of the stresses profile are related by the temperature, treatment time and the rotation angle φ. ……………… DSL139 Mrs. Hanis Ayuni Mohd Yusof Centre of Nanotechnology, Precision and Advanced Materials, Mechanical Engineering Department, University of Malaya, Malaysia
Superplastic Boronizing of Duplex Stainless Steel through Dual Compression Method H.A.M. Yusof1, I. Jauhari1, N.H.A. Aziz1 1Centre of Nanotechnology, Precision and Advanced Materials, Mechanical Engineering Department, Faculty of Engineering, University Malaya, 50603 Kuala Lumpur, Malaysia. Superplastic boronizing (SPB) is a process that combines boronizing with superplastic deformation. The basic principle of superplastic boronizing process is to conduct boronizing while the specimen is undergoing superplastic deformation [1]. In this work, superplastic boronizing (SPB) of duplex stainless steel (DSS) under dual compression mode has been studied. Dual compression method is a process with combination of two compression method. Here, the first step of compression method for superplastic deformation was focused only at the surface asperities of the specimen with no obvious bulk deformation to the specimen after the SPB. This process was conducted on
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duplex stainless steel (DSS) which has been thermo‐mechanically treated to obtain fine grain microstructure and exhibit superplasticity. Effort was being put in obtaining hard surface through SPB by focusing on the surface roughness, initial pressure and powder size effects. SPB was conducted at 1223 K, with various time of boronizing under three different surface roughness, Ra (0.9 μm, 0.1 μm, and 0.03 μm), three different initial pressure (25 MPa, 49 MPa, and 74 MPa) and four different boron powder particle sizes (20 μm, 45 μm, 150 μm, and 850 μm) conditions. Through the SPB method, boronizing properties were improved and boronizing time was shortened [2]. The second step of compression method for superplastic deformation process concentrates on the deformation of bulk material by applying different strain rate (1 x 10‐2 s‐1 and 1 x 10‐3 s‐1) at various processing time. Several samples from the first method were chosen for this bulk deformation process and the process occurs without applying boron powder. This method is believed can produced thick boride layer with high hardness. Comparison study using as‐received DSS with coarse microstructure also was performed, with results confirming the contribution of superplasticity to the SPB process. [1] C.H. Xu, J.K. Xi, W. Gao, Scipta Materialia, 34, 455 (1996). [2] R. Hassan, I. Jauhari, H. Ogiyama, and R.D. Ramdan, Key Engineering Materials, 326‐328, 1233 (2006). ……………… DSL403 Prof. Branko Skoric University of Novi Sad, Novi Sad, Trg D. Obradovica 6, SRB Characterization of Hard Coatings Modificated with Nitrogen Implantation B. Skoric, D. Kakas, A. Miletic University of Novi Sad, Novi Sad, Trg D. Obradovica 6, SRB. In this paper, we present the results of a study of TiN films which are deposited by a Physical Vapor Deposition and Ion Beam Assisted Deposition. In the present investigation the subsequent ion implantation was provided with N2+ ions. The ion implantation was applied to enhance the mechanical properties of surface. The film deposition process exerts a number of effects such as crystallographic orientation, morphology, topography, densification of the films. The evolution of the microstructure from porous and columnar grains to densel packed grains is accompanied by changes in mechanical and physical properties. A variety of analytic techniques were used for characterization, such as scratch test, calo test, SEM, AFM, XRD and EDAX. The experimental results indicated that the mechanical hardness is elevated by penetration of nitrogen, whereas the Young’s modulus is significantly elevated. Thin hard coatings deposited by physical vapour deposition (PVD), e.g. titanium nitride (TiN) are frequently used to improve tribological performance in many engineering applications. Ion bombardment during vapour depositionof thin films, colled ion beam assisted deposition (IBAD), exerts a number of effects such as densification, changes in grain size, crystallographic orientation, morphology and topography of the films. This paper describes the successful use of the nanoindentation technique for determination of hardness and elastic modulus. In the nanoindentation technique, hardness and Young’s modulus can be determined by the Oliver and Pharr method. Therefore, in recent years, a number of measurements have been made in which nanoindentation and AFM have been combined. [1] K. Mogensen, N. Thomsen, S. Esikilden, C. Mathiasen and J.Bottiger, Surface and Coatings Technology 99, 140 (1998). [2] W. Ensinger,Surface and Coatings Technology 99, 1 (1998) [3] J.C.A. Batista, C. Godoy, A. Matthews, A. Leyland, , Surface Engineering, 9, 37 ( 2003). ……………… VIP‐DSL033 Prof. Huseyin Cimenoglu
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Department of Metallurgical and Materials Engineering, Istanbul Technical University, 34469, Maslak, Istanbul, Turkey
The Effect of Oxidation on The structure and Mechanical Properties of (Zr, Hf)N Coatings Erdem Atar1, E. Sabri Kayali2 and Huseyin Cimenoglu2* 1 Gebze Institute of Technology, Material Science and Engineering Department, 41400, Gebze, Kocaeli, Turkey 2 Istanbul Technical University, Department of Metallurgy and Materials Engineering, 34469, Ayazaga, Istanbul, Turkey In the present study, the effect of oxidation on the structure and the mechanical properties of ternary (Zr, Hf) N coatings, whose Hf content was varied between 0 and 21 wt.%, has been systematically examined. Coatings were applied on AISI D2 tool steel plates by arc physical vapor deposition (PVD). Oxidation was conducted at 400oC for times up to 12 h in air. Ternary (Zr, Hf)N coatings are found to be more susceptible towards oxidation compared to binary ZrN coating. Thermal oxidation results in the formation of a mixed ZrO2 and HfO2 oxide layer. Hardness measurements revealed that the hardness values of Hf free and Hf alloyed coatings were very close to each other. However, the change in Hf content of the coating was accompanied by an increase in critical cracking load determined by the scratch test. Upon oxidation for times up to 12 h, (Zr, Hf)N coatings exhibited a gradual decrease in hardness, on the other hand, showed an increase in the scratch adhesion. The beneficial effect of Hf on mechanical properties decreased upon oxidation when compared to as‐deposited state. Keywords: Adhesion, Coating, Hardness, Hafnium, PVD, ZrN, *Corresponding author: Tel: +90‐212‐285‐6834 Fax: +90‐212‐285‐3427 E‐mail:
[email protected] ……………… DSL148 Dr. Keddam Mourad Faculté de Génie Mécanique et Génie des Procédés, Département de S.D.M, B.PN°32, 16111, U.S.T.H.B, El‐Alia, Bab‐Ezzouar, Algiers, Algeria
An Approach for Analyzing the Growth Kinetics of Fe2B Phase on AISI 1018 Steel M. Keddam Faculté de Génie Mécanique et Génie des Procédés, Département de S.D.M, B.PN°32, 16111, U.S.T.H.B, El‐Alia, Bab‐Ezzouar, Algiers, Algeria. A simulation of the growth kinetics of iron boride forming on AISI 1018 carbon steel was performed using a simplified kinetic model. This model including the effect of the incubation time during the formation of iron boride, was applied in order to evaluate the parabolic growth constant at the ( ) interface depending on the paste‐ boriding parameters such as the process temperature and the boron potential reflected by the corresponding value of the boron surface content. The simulation results were found to be in a good agreement with the experimental data derived from the literature [1]. It was possible to establish a relationship between the parabolic growth constant and the boron potential at a given temperature.
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Keywords: Boriding, Fe‐B binary system, Iron boride, Parabolic growth constant. [1] I. Campos‐Silva, M. Ortiz‐Dominguez, C. VillaVelazquez, R. Escobar, N. Lopez, Defect and Diff. Forum, 272,79‐86, (2007). ……………… DSL173 Prof. T. Aabu Bakar NCPST and MPRC, Dublin City University, Dublin‐9, Ireland
Mechanical Performance of the Annealed NiTi Shape Memory Alloy Coating onto 316L Stainless Bio‐Steel T. A. A. Bakar 1*, M. Rahman 2, D. P. Dowling 2, M. S. J. Hashmi 1 J. Stokes 1, 1 NCPST and MPRC, Dublin City University, Dublin‐9, Ireland. 2 School of Electrical, Electronic & Mechanical Engineering, University College Dublin, Dublin‐4, Ireland. This paper presents the mechanical performance of the annealed NiTi Shape Memory Alloy (SMA) coating deposited onto 316L stainless steel substrate. The as‐deposited SMA coating, Ni55.87Ti44.13, showed an amorphous behaviour. A crystalline NiTi (SMA) coating was produced by annealing the deposited coatings in a vacuum furnace using argon inert gas. The annealed NiTi coatings were characterised to investigate their tribological potential as an interlayer to the hard coating. The NiTi phases and structure were determined by x‐ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscope (AFM). The crystallisation and the transformation temperature of NiTi SMA coatings were investigated using the differential scanning calorimetry (DSC) and the mechanical properties by Rockwell C adhesion test, scratch test and wear test. The effects of the annealing treatment on adhesion and wear properties were studied using the SEM and the EDX. The results showed that crystalline NiTi coatings annealed above the coatings crystallisation temperature, 600 ºC for durations of 30 minutes exhibited higher elastic performance, thus reducing wear effects applied. Adding a hard top layer would potentially provide a hard coating with an interlayer capable of absorbing impact which would be very suitable for ball joints used in hip replacement therapy [2]. [1] N. W. Botterill and D. M. Grant, Mater. Sci. Eng. A, 378, 424‐428, (2004). [2] Y.Zhang, Y. Cheng and D.S. Grummon, Mater. Sci. Eng. A, 438‐440, 710‐713, (2006) ……………… DSL176 Mrs. Ivonne Infante Danzo Department of Materials Science and Engineering, Ghent University, Technologiepark 903, B‐9052 Gent, Belgium
Characterization of Intermetallic Compounds Formed During Hot Dipping of Electrical Steel in a Hypo‐Eutectic Al‐Si Bath I. Infante Danzo1, K. Verbeken1 and Y. Houbaert1 Department of Metallurgy and Materials Science, Ghent University Technologiepark 903, B‐9052 Gent, Belgium
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In order to improve the magnetic properties of electrical steel, it may be desirable to increase the Si and/or Al content of the steel. An alternative route to do so is through the application of an Al‐Si‐rich coating on the steel substrate using a hot dipping process, followed by diffusion annealing. Previously, a number of experiments were performed by dipping in pure Al, Al + 10 wt.‐%Si (hypoeutectic composition) and Al + 25 wt.‐% Si (hypereutectic composition). After series of dipping experiments, followed by the evaluation of the coating and of the formed intermetallic phases, the use of a hypoeutectic Al‐Si‐bath was recommended, because of certain advantages: hypoeutectic concentrations allow lower dipping temperatures and reduce the formation of ordered Fe‐Si‐ structures causing brittleness in the coating and substrate. The present work reports on new results concerning the hot dipping in hypoeutectic bathes. An Al + 1 wt.‐%Si bath was used to coat electrical steel substrates with different silicon contents with dipping times, varying between 0 to 20 seconds, after a preheating of the samples to a temperature of 700 °C. A thorough characterization of the formed intermetallics was made by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X‐Ray Diffraction (XRD). Three different compounds were identified as Fe2Al5, FeAl3 and a nearly pure Al phase. Their compositions were in good agreement with the results reported in literature obtained in other types of experiments. ……………… DSL244 Mr. Seong‐JunLee Mokpo maritime university, Mokpo‐city, Jeonnam 530‐729, South Korea
A Study on Cavitation and Erosion Corrosion Behavior of Zn Thermal Spray Coated Material in Sea Water Environment S.J. Kim1, T.Y. Jang2, Y.J Seo3, S.J. Lee4 1,4 Mokpo maritime university, Mokpo‐city, Jeonnam 530‐729, South Korea 2 Hyuksung industry, Seong Nam‐city, Gyeonggi, South Korea 3 TaeKyung industry, Mokpo‐city, Jeonnam 530‐729, South Korea The cavitation and erosion corrosion implies damage to materials due to the shock pressure by bubbles form and collapse at a metal surface [1]. Ship’s hull is typically protected by coating system, sacrificial anode protection and impressed current cathodic protection (ICCP) system. However, ship’s aft is exposed to more severe environment such as tide, velocity of ship, cavitation and erosion corrosion. Therefore, we conducted thermal spray coating to get the much excellent electrochemical and anti‐cavitation characteristics in sea water environment [2~3]. In this study, cavitation damage was investigated by using the piezoelectric vibrator with 20KHz, 50㎛to cavity generation apparatus. The cavitation‐erosion tester was manu‐factured according to ASTM‐G32. The cavitation behavior of thermal spray coated specimens was examined with the point of weight loss measurement and surface morphology observation. The base metal by thermal spray coating protected in sea water. The erosion rates of coating considerably increased at the initial stage of cavitation test in sea water. The weight loss in sealed for Zn thermal spray coating was smaller than that of Zn thermal spray coating. Acknowledgement: This research was supported by R&D fund of Ministry of Land, Transport and Maritime Affairs of Korean government. [1] S. K. JANG, S. C. KO, M. S. HAN, S. J. KIM. Interfinish 2008, p 533 (2008) [2] S. J. KIM, J. Y. JEONG, J. I. KIM. Journal of ceramic processing research, Vol. 8, No. 3, p 296‐299 (2007) [3] J.J. KIM, J.S. PARK, S.B. JOON, J. Corrs. Sci. Soc. of Korea, Vol. 20, No. 2, p132~138, (1991) ……………… DSL190 Prof. Arvaidas Galdikas
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Physics Department, Kaunas University of Technology, Kaunas (Lithuania)
Analysis of depth profile components at the Interface of Ti6242 Alloy and SiC, SixNy Coatings after High Temperature Oxidation in Air A.Galdikasa, J.P.Rivièreb, T.Moskaliovienea L.Pichonb (a) Physics Department, Kaunas University of Technology, Kaunas (Lithuania) (b) Laboratoire de Physique des Matériaux, University of Poitiers, Poitiers (France), We have analyzed the interfacial elemental depth profile evolution after high temperature isothermal oxidation of SixCy and SixNy protective coatings deposited by dynamic ion mixing on a Ti6242 alloy (Ti‐6Al‐2Sn‐4Zr‐2Mo). The amorphous SixCy (x/y~1,1) and SixNy (x/y~2) coatings 0,25‐0,21mm thick respectively were produced by sputtering SiC and Si3N4 targets with a 1,2 keV Ar+ ion beam and the growing films were bombarded with 120 keV Ar+ ions. Isothermal oxidations tests have been carried out at 600°C during 100 hours in 1 atm flowing synthetic air (80% N2, 20% O2). The structural modifications consist principally in the formation of SiO2 at the surface and TiSi compounds at the interface. We have observed a non‐monotonous depth distribution of zirconium in GDOES and SIMS depth profiles after oxidation of SiC/Ti6242 and SiN/Ti6242 and we propose a kinetic model based on rate equations for analyzing the results. This model includes microprocesses taking place during oxidation in air such as: adsorption of nitrogen and oxygen, diffusion of components through the film and interface, formation of chemical compounds. The calculations are based on a monolayer approach where the equations are written for each component in each monolayer. It is shown by modeling that non‐monotonous depth profile of zirconium occurs because zirconium from Ti6242 alloy is forming a zirconium nitride compound when nitrogen atoms reach the film/alloy interface. As a result the atomic concentration of zirconium decreases at the interface which induces a diffusion flux of zirconium from the bulk to the interface. This process leads to the increase of the total amount of zirconium at the film interface and thus formation of non‐monotonous depth profile. It is shown that the process of zirconium nitride formation at the interface plays an important role and acts as a protective barrier for further penetration of nitrogen atoms into the Ti6242 alloy. ……………… DSL199 Dr. Pranesh Sengupta Institut für Geologie, Mineralogie und Geophysik; Ruhr Universität Bochum, D‐44780 Bochum, Germany
Development of Functionally Graded Composite Coating on Alloy 690 using PLD (Pulsed Laser Deposition) Technique P. Sengupta1, 2. H.‐W. Becker3 and S. Chakraborty1 1Institut für Geologie, Mineralogie und Geophysik; Ruhr Universität Bochum, D‐44780 Bochum, Germany 2Materials Science Division, Bhabha Atomic Research Centre, Mumbai 400 085, India 3Fakultät für Physik und Astronomie; Ruhr Universität Bochum, D‐44780 Bochum, Germany Superalloy 690 (Ni: 58.0 min., Cr: 27.0 – 31.0, Fe: 7.0‐ 11.0, C: 0.05 max., Mn: 0.50 max etc.; all in wt%) is extensively used in waste vitrification plants as the material of construction for melter pot, thermowell, electrodes, pour spout assembly etc. Fast degradation and premature failure of these components under harsh service conditions not only make the processes more expensive, they also pose serious problems in storage and disposal of the metallic waste. The sought solution to these problems is enhancement of the life span of the metallic components as much as possible. In a step toward this goal, we have coated Alloy 690 with functionally graded
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Yttria‐stabilized Zirconia (YSZ) using a Pulsed Laser Deposition technique. Successive layers of 10 – 100 nanometer scale thin films of different compositions were deposited on the alloy using excimer laser (193 nm) for ablation of sintered target materials of desired compositions. Relevant experiments have been carried out in the laboratory under controlled atmosphere. Small Alloy 690 coupons coated with functionally graded YSZ thin films were exposed to different temperatures (800 – 1200°C) for different times (1 – 6 hours). In each case, the interfaces were characterized using Rutherford Backscattering Spectroscopy (RBS). This allows us to resolve and analyze the compositions of phases at the nanometer scale. Further, to compare the performances of coated Alloy 690 with as received ones under partially simulated plant conditions, thin films of sodium barium borosilicate base glass were deposited and the samples were also annealed and observed with RBS as well as SEM and white light interference microscopy. Results obtained from these experiments will be presented. ……………… DSL237 Prof. Jolanta Baranowska Westpomeranian University of Technology, Szczecin, Piastów 19, PL70‐310, Poland
The kinetics of Gas Nitrided Layer Growth on Austenitic Stainless Steel J. Baranowska Westpomeranian University of Technology, Szczecin, Piastów 19, PL70‐310, Poland. Austenitic stainless steel is commonly used in many industrial applications thanks to its very good corrosion resistance. However, these applications are limited due to relatively low mechanical response of this steel. The nitriding is one of the typical treatments used to overcome these disadventages. In case of austenitic stainless steel the low temperature nitriding (at temperature below 500°C) is a very promising process, which allows the hard and corrosion resistant layers to be obtained thanks to formation of a so‐called S‐phase [1]. The growth of the layers in these conditions is very specific and not yet explained. The kinetics of layer growth is much higher than it could be explained by nitrogen diffusivity in austenite, and usually it is attributed to high energetic state of nitrogen plasma used in the process [2, 3]. The paper presents the results of investigations on gas nitrided austenitic stainless steel. The treatment was conducted for various temperatures (400‐570°C), gas compositions of atmospheres used (20‐100% NH3) and times (0.5‐12h). The layers were investigated by X‐ray diffraction, Light and Electron Microscopy and Glow Discharge Optical Spectrometry. The kinetics of layer growth has been analysed in terms of the process parameters and compared to the data presented for plasma treated steel. The specific nitrogen profiles of nitrided layers is discussed in the context of layers’ microstructure and phase composition. [1] K. Ichii, K. Fujimura, T. Takase. Tech. Rep. Kansai. Univ. 27, 135 (1986). [2] A.Brokman, F.R. Tuler. J.Appl.Phys. 1, 52, 468 (1981) [3] L.Pranevicius, C.Templier, J.P.Rivier, at al. Surf. Coat. Techn. 135, 250 (2001) ……………… DSL377 Prof. Constantina Kollia National Technical University of Athens, School of Chemical Engineering, Laboratory of General Chemistry, 9, Iroon Polytechniou Str., Zografou Campus 15780, Greece
Pulse Electrolysis for the Production of Hard Ni/TiO2‐ZrO2 Composite Coatings I. Deligkiozi, M.M. Dardavila and C. Kollia National Technical University of Athens, School of Chemical Engineering,
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Laboratory of General Chemistry, 9, Iroon Polytechniou Str., Zografou Campus 15780, GR. The electrolytic codeposition has withdrawn the interest as an alternative method for the preparation of metal matrix composite electrocoatings (MMCs) with improved properties. The isotropy of the properties of the composite electrocoatings depends directly on the incorporation percentage and the uniform distribution of chemically inert particles, such as carbides or oxides, into the metal matrix. Moreover, the application of a current periodically varied by time during electrodeposition, i.e. pulse current (P.C.) instead of the commonly used direct current (D.C.), has been proved that leads to the preparation of surfaces with well‐defined properties [1, 2]. In this work nickel matrix composite electrocoatings including oxides of elements of the group “4” of the periodic table as particulate matter, i.e. TiO2 and ZrO2 particles, were produced under direct and pulse current conditions. A Watts type bath was used as electrolytic bath and the Ni/TiO2‐ΖrO2 electrocoatings were deposited on rotated brass electrodes. The synergetic action of both the pulse application and the simultaneous codeposition of two different types of particles on the structure, the morphological characteristics and the microhardness of the composite electrocoatings, was studied. It was found out that the codeposition of both the TiO2 and ZrO2 particles into the metal matrix is successful. The variation of the pulse current parameters together with the codeposition of the particles selectively on the crystalline boundaries influences the texture of the deposits, modifying the particles incorporation percentage and their distribution in the matrix. This ascertainment also influences the properties of the composite electrocoatings; it was measured that increases threefold the Vickers microhardness of P.C. electrodeposits in comparison with the values taken under conventional electrolysis conditions. [1] Wei Wang, Feng‐Yan Hou, Hui Wang, He‐Tong Guo, Scripta Materialia 53, 613 (2005). [2] C. Kollia, C. Patta, P. Vassiliou, V. Kasselouri, Revista de Metalurgia‐Madrid,svp. 227 (2005). ……………… DSL453 Mr. hamid Bolvardi Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran
Effects of Load and Sliding Speed on Tribological Behavior of Plasma Sprayed Bronze‐Alumina coatings H.Bolvardi , H.Khorsand1, P.Movahed1, A.Etaati1 1Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran. Metal matrix composites are advanced composite materials that exhibit tremendous potential for a number of important applications in all sectors. Furthermore, bronze materials are high potential copper alloys comprise of good wear resistance, fatigue resistance, corrosion resistance, etc. These alloys are widely used in many engineering applications. They offer easier processing as compared with titanium, and lower density compared with steel. Among the most recent surface modifications techniques, plasma spray has been successfully applied to these coatings. In this investigation, an attempt has been made to analyze the sliding wear response of Bronze‐ Alumina coats over a range of applied pressures and sliding speeds. Wear processes are discussed in the light of the microstructural observations combined with wear surfaces and debris particles examinations. [1] T. Sornakumara and A. Senthil Kumarb, journal of materials processing technology, 202, 402 ( 2008 ). [2] B.K. Prasad, Wear, 257, 110 (2004). ………………
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DSL259 Dr. Marcin Golabczak Technical University of Lodz, Department of Production Engineering, Stefanowskiego 1/15 Str., 90‐924 Lodz, Poland
Notices on Method of Thickness Evaluation of the TiN Layers on Magnesium Alloys M. Golabczak1, A. Konstantynowicz1 1Technical University of Lodz, Department of Production Engineering, Stefanowskiego 1/15 Str., 90‐924 Lodz, PL. Widely used in mechanics is the method of surface parameters investigation by in¬den¬ta‐tion of some kind of penetrator into surface under test and registration of the in¬den¬ta‐tion/load dependence through the whole test duration. A small ball made of har¬de¬ned steel or diamond pyramid, most often so‐called Berkovich pyramid, are used for pe¬ne¬t¬ra‐tion. An actuator performing indentation process is used for displacement en¬for¬ce¬ment as well as for load measurement. Mainly two types of devices are in use: ba¬sed on pie¬zo¬e¬le¬c‐tric effect or purely electromagnetic LVDT (Linear Variable Displacement Transducer). Knowledge about pe¬ne¬t¬ra¬tor tip is es¬sen¬tial for the proper evaluation of the measured parameters and knowled¬ge about ac¬tu¬at¬ion method is also desired for better identification of the whole sy¬s¬tem pa¬ra¬me¬ters when using DSP (Digital Signal Processing) type algorithms at the stage of elaboration the data from ex¬pe¬ri¬ment. In this paper we deal with some kind of DSP elaboration of the ex¬pe¬ri¬men¬tal data. Our at¬ti¬tu¬de is based on successive digital filtration applied to the ex¬pe¬ri¬men¬tal data as well as to the intermediate stages of calculation, especially for com¬plian¬ce estimation. Pro¬po¬sed method has been applied to the experimental data ob¬tai¬ned by indentation of the in¬ve¬s¬ti‐ga¬ted surface with Berkovich pyramid driven by pie¬zo¬e¬le¬c¬tric actuator. The Bo¬u¬s‐sinesq/Sneddon theory has been used as the basis of our a¬na¬ly¬sis. Titanium azide layers imposed on magnesium alloy with using PVD method have been tested. Obtained results especially due to the hardness/indentation plot allow eva¬lu¬a¬ting layer thick¬ness, which should be also compared with thickness evaluated by other methods. [1] I.N. Sneddon, Proc. of the Cambridge Ph.S., 42, 29 (1946). [2] I.N. Sneddon, Int. J. Eng.S., 3, 47 (1965). ……………… DSL049 Prof. Shahram Ahmadi Department of Material Science, Faculty of Engineering, Tarbiat Modares University of Technology, Tehran, Iran
Effects of Multiple Hardening Treatment on Mechanical Properties and Electrical Resistance of an Al‐ Li‐Cu Alloy A. Shokuhfar1, S. Ahmadi2, A. Rezaei1 , H. Arabi3 1 Department of Material Science, Faculty of Mechanical Engineering, K. N. Toosi University of Technology, Tehran, Iran 2 Department of Material Science, Faculty of Engineering, Tarbiat Modares University, Tehran, Iran 3 Center of Excellence of Advanced Materials and Processing (CEAMP), Department of Materials Science and Engineering, Iran university of Science & Technology (IUST), Tehran, Iran
[email protected]
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In this research, effects of ageing process in two, three, and four cycles on the mechanical properties (i.e. hardness, yield strength, UTS, and elongation) and electrical resistance of an Al‐ Li‐ Cu alloy was studied by hardness, stress, and electrical resistance tests. Moreover, transmission electron microscope (TEM) was utilized to identify the strengthening phases in structure of the alloy. Results showed that age hardening of the alloy in four cycles (i.e. room temperature, 190ºC, 150ºC, and 100ºC respectively) can increase ultimate tensile strength up to 640 Mpa. In fact, for the first time in this research it is proof that mechanical properties of the Al‐Li‐ Cu alloy can be come top with the aide of cyclic ageing treatment. TEM observations also showed that plate shape T1 phase was the most important strengthening phase in the structure. Keywords: multi‐ step hardening; selected area diffraction pattern (SADF); interplanar spacing (d); natural aging; activation energy ……………… DSL144 Mr. ArashYazdani Department of materials and metallurgical Engineering, Iran University of Science and Technology, Iran
Deposition of Nano Sized Titanium Nitride on H11 Tool Steel Using Active Screen Plasma Nitriding Method A.Yazdani1, H.Aghajani1, M.Soltanieh1 Department of materials and metallurgical Engineering, Iran University of Science and Technology, Tehran, 16844, Iran. Active screen plasma nitriding (ASPN) is an emerging surface engineering technology that offers many advantages over the conventional DC plasma nitriding (DCPN). In this research plasma nitriding of H11 tool steel, using titanium active screen was investigated. Samples were plasma nitrided at 550 oC, for 5, 7.5 and 10 h with 3 different gas mixtures of H2/N2 %= 3, 4, 5. The coating microstructure and phase analysis were investigated using Scanning Electron Microscopy and X‐ray Diffraction technique. The dominate phase in compound layer was TiN. With increasing processing time, the layer thickness was increased. According to Scanning Electron Microscopy results, the sample surface was formed of nano sized and particulate titanium nitride particles. It was proved that with increasing H2% in gas mixtures, better surface quality, golden yellow color, was obtained. Also the intensity of TiN peaks and layer thickness were increased, significantly. Another important result of higher amount of H2 content is the formation of coarse particles at titanium nitride layer. References [1]. K. K. Yee, `Protective Coatings for Metals by Chemical Vapour Deposition`, Int. Met.Rev, 1, 19‐42, 1978. [2]. H. Dun, P. Pan, F. R. White, R. W. Douse,` Mechanisms of Plasms‐Enhanced Silicon Nitride Deposition Using SiH4/N2 Mixture`, J. Electrochem. Soc., 128, 1555.1981. [3]. J. C. Zesch, R. A. Lujan, V. R. Deline, `Glow Discharge Optical Spectroscopy Measurement of Dopant Concentrations in a Si:H`, J. Non‐Cryst. Solids, 35‐36, 273‐277, 1980. [4]. K. S. Mogensen, C. Mathiasen n, S. S. Eskildse ,H. Stori, J. Bottiger, `The time development of pulsed‐DC production plasmas used for deposition of TiN`, Surf. Coat. Technol. 102, 35‐40,1998. [5]. J. S. You, C. S. Kang, S. H. Lee, C. Pfohl, K. T. Rie,`Thermal characteristics of a Zr(B,C,N) coated layer manufactured by the PACVD process`, Surf. Coat. Technol. 112, 230‐235, 1999. [6]. M. Charbonnier, M. Romand,`Tin‐free electroless metallization of glass substrates using different PACVD surface treatment processes`, Surf. Coat. Technol. 162, 19‐30,2002. [7]. I. Endler, E. Wolf, A. Leonhardt, V. Richter,`preparation, characterization and wear
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behaviuor of PACVD cermets`, Surf. Coat. Technol. 72, 37‐42, 1995. [8]. O. Salas, K. Kearns, S. Carrera, J. J. Moore, `Tribological behavior of candidate coating for Al die casting dies`, Surf. Coat. Technol. 172, 117‐127, 2003. [9]. Z. Cheng, H. Peng, G. Xie, Y. Shi, Surf. Coat. Technol. `Annealing studies of TiN deposited by plasma‐assisted CVD`, 138, 237‐241, 2001. [10]. J. Park, D. Kim, Y. Kim, K. Lee, H. Lee, S. Ahn, `Improvement of the biocompatibility and mechanical properties of surgical tools with TiN coating by PACVD`, Thin Solid Films,435, 102‐107, 2003..... زا PACVD رازبا د.وف يور ..... [11]. E. Badisch, C. Mitterer, P. H. Mayrhofer, G. Mori, R. J. Bakker, J. Brenner, H. Stori,`Characterization of tribo‐ layers on self‐lubricating PACVD TiN coating`, Thin Solid Films,460, 125‐132, 2004. ……………… DSL213 Dr. Levent Cenk Kumruoğlu Sakarya University Engineering Department Department of Materials Science and Metallurgical Engineering Esentepe Campus, Sakarya, TR, 54187 E‐ Turkey
Aqueous Electrolyte Plasma Hardening of Pure Iron Substrate Levent Cenk Kumruoğlu, Soner Özden ERTÜRK, Ahmet Özel, Abdullah Mimaroğlu Faculty of Engineering, University of Sakarya, Esentepe Campus, Sakarya, TR, 54187, Turkey
[email protected] +90 264 295 57 90 In this study, surface carburizing and hardening of pure iron were prepared in aqueous electrolyte, which consists of pure water, Na2CO3, glycerin, Na2B4O7, KOH and carbamide, for various period of time by plasma electrolytic surface treatment. The composition, structure, and hardness properties of the carburizing layer were studied by X‐ ray Diffraction (XRD), Scanning Electron Microscope (SEM) and micro‐hardness tester. The hardness of the carbon‐ rich layer on the substrate was 750 Hv. Keywords: Pure Iron; Carburizing; Plasma electrolytic surface hardening; SEM, Microhardness ……………… DSL227 Mr. Farid Siyahjani Istanbul Technical University, Materials and Metallurgical Engineering Department, Maslak, Istanbul, Turkey
Nitrocarburizing of c15 and ck15 Quality Steels in Liquid Cyanate Bath Farid Siyahjani Istanbul Technical University, Materials and Metallurgical Engineering Department, Maslak, Istanbul, Turkey In this study, nitrocarburizing of C15 and CK45 was done in liquid cyanate bath at 580ºC. Fe3N (ε) layers has been formed on the surface of both steel, while Fe4N (γ´) developed only at C15 steel after long time. Hybrid nitrocarburizing layers that consist of Fe4N (γ´) layer at C15 steel, show lower hardness in comparing Fe3N (ε) layer. In addition, the time of heat treatment will have significant effect on thickness and structure of steel. After nitrocarburizing, the steels were examined by x‐ray diffraction analyzer, scanning electron microscopic survey, micro hardness test and wear testing machine.
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References [1] T. Bell Met. Eng. Q., May, 16 (1976)1‐13. [2] IndustrialHeatingLXIII (1996), p.47. [3] G.Wahl, Adv.Mater.Process.4 (1996)37‐38. [4] C.Razim ,GearTechnology(March/April)1994.18‐24. ……………… DSL292 Mrs. Ana Lúcia do Amaral Escada São Paulo State University‐UNESP, Guaratinguetá, Av. Dr. Ariberto Pereira da Cunha, 333, Pedregulho, SP, Brazil
AFM Analysis of Apatite Coating on Ti‐7.5Mo Alloys A.L.A. Escada1, M.C.R. Alves Rezende2, D. Rodrigues Jr3, J.P.B.Machado4, M.I. Kimaid1, A.P.R.Alves Claro1 1 São Paulo State University‐UNESP, Guaratinguetá, Av. Dr. Ariberto Pereira da Cunha, 333, Pedregulho, SP, Brazil. 2 São Paulo State University ‐UNESP, Araçatuba, Rua José Bonifácio, 1193, Vila Mendonça, SP, Brazil. 3 University of São Paulo (USP), Lorena, SP, Brazil 4 National Institute for Space Research –INPE, São José dos Campos, Av. dos Astronautas, 1758, Jd. Granja, SP, Titanium and its alloys have been used in dentistry due their excellent corrosion resistance and biocompatibility. However, titanium coating is bioinert material and it cannot bond chemically to bone tissue. The purpose of this work was evaluated bioactivity of Ti‐7,5Mo alloy after alkaline treatment, heat treatment and soaking in SBF. Ingots were obtained from titanium and molybdenum by using an arc‐melting furnace. They were machined in order to achieve microstructure and morphology next to dental implants. Average surface roughness (Ra) was measured by a roughness meter and disc samples (13 mm in diameter and 4 mm in thickness) were cut to form two distinct groups according average roughness (1.3 mm and 2.6 mm). For alkaline surface treatment, samples were immersed in NaOH aqueous solution with 5.0M at 80ºC for 3 days, washed with distilled water and dried at 40ºC for 24h. After alkaline treatment samples were heat treated at 600ºC for 1h in an electrical furnace in air. Then, all samples were immersed in SBF (Simulated Body Fluid) for 7 and 14 days to form a calcium phosphate (Ca‐ P) coating on the surface. Surfaces were characterized by using an atomic force microscopy (AFM) and a scanning electron microscopy (SEM). Analysis indicated that the surface was covered with a thin sodium titanate layer after NaOH treatment. This chemical treatment on different surfaces exposed reactive groups and made possible to create nanoscale topography. It was observed Ca‐P deposits with 90–200nm in equivalent diameter after 7 and 14 days on both roughnesses samples. The immersion time used, made possible to form a continuous Ca‐P film on titanium substrates. It was found that substrate surface roughness affected the apatite formation. The results indicated that calcium phosphate could form on surface of Ti‐ 7.5Mo experimental alloy with better hidrofilicity for 2.6 mm. ……………… DSL505 Mr. F. Fazlalipour Iran Radiator Company, Tehran, R&D Dept, Iran
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Comparative Tribological Behaviour and Wear Mechanisms of V(N,C) and VC Hard Diffusion Coatings against WC/Co Cemented Tungsten Carbide F. Fazlalipour1, N. Shakib1, M. Niki Nushari1, A. Shokuhfar 2 1Iran Radiator Company, Tehran, R&D Dept 2K.N. Toosi University of Technology,Iran In this work, the wear mechanisms and tribological properties of Vanadium Carbide (VC) and Vanadium Nitrocarbide (V(N,C)) layers coated separately on DIN 1.2367 hot work steel disks were compared against WC/Co cemented tungsten carbide pin. The V(N,C) layer was produced by a duplex surface treatment involving the gas pre‐nitrocarburising followed by thermo‐reactive diffusion (TRD) vanadizing technique. Coating layers were characterized by microstructure and microhardness methods and X‐ray diffraction analysis. The wear and friction tests were carried out on pin‐on‐disk configuration in a dry test condition under 70, 140 and 210 N loads at 0.13 m/s sliding speed for 700m displacement. Effect of applied load on specific wear rate and coefficient of friction was investigated. Wear mechanisms were determined by SEM microscope in back scattered and secondary electron mode (BSI) accompanied by EDS analyzer. In this study, results revealed that V(N,C) coating offers lower wear rate and better tribological properties than that of VC due to pre‐nitrocarborizing and formation of protective oxide layer as a result of temperature increment during sliding. Finally, it was determined that contribution of oxidizing and polishing of this protective oxide layer is the dominant wear mechanism in the V(N,C) coated steel. Whereas, in the case of VC coating plastic deformation together with severe abrasive wear play a major role in degradation of materials. Keywords: Wear mechanism, carbide coating, Duplex, TRD, vanadium nitrocarbide ……………… DSL063 Mr. Gheriani Rachid Physics department, Faculty of science, university of Ouargla, Algeria
Effect of Heat Treatments on the Structural and Mechanical Properties of Ti Thin Films Deposited on Steel Substrates by PVD Method. R. Gheriani1 , R. Halimi2. 1Physical laboratory of Materials, University of Ouargla , 30.000‐ Algeria. 2Unity of research, Materials and applications, University of Constantine, 25.000 – Algeria. Titanium carbides are well known materials with great scientific and technological interest. The applications of these materials take advantage of the fact that they are very hard, refractory and that they have metallic properties. In this work, We have studied the influence of the heat treatment temperatures ( 400‐1000°C) on the interaction between the titanium thin films and steel substrates. Steel substrates, 100C6 type (AFNOR norms), containing approximately 1 wt % of carbon, were coated at 200°C with titanium thin films by magnetron sputtering. The samples were characterized by X ray diffraction (XRD), Auger electron spectroscopy (AES) and scanning electron microscopy (SEM). Vikers micro‐hardness measurements carried out on the annealed samples showed that the micro‐hardness increases with annealing temperature, reaches a maximum (3500 kg/mm2), then decreases progressively. The growth of micro‐hardness is due to the diffusion of the carbon, and to the formation of titanium carbide. However, the decrease of micro‐hardness is associated to the diffusion of iron and the formation of iron oxide (Fe2O3). At higher temperatures, we note the formation of titanium oxide (TiO2). ………………
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VIP‐DSL009 Prof. I. E. Campos Silva Instituto Politécnico Nacional, SEPI‐ESIME U.P. Adolfo López Mateos, Zacatenco, México. 07738. D. F. México
Production of a Multicomponential Layers on a 99.8% Purity Iron by the Two Stage Boro‐Nitriding Process: Microstructural and Mechanical Characterization O. A. Gómez‐Vargas1, I. Campos‐Silva1, U. Figueroa‐López2, M. Elías‐Espinosa1, E. Hernández‐Sánchez1 1Instituto Politécnico Nacional, SEPI‐ESIME U.P. Adolfo López Mateos, Zacatenco. México. 07738. D. F. México. 2Instituto Tecnológico y de Estudios Superiores de Monterrey CEM, Carretera Lago. De Guadalupe. km 3.5, Atizapán, Edo. de México. 52926. Nowadays, there are number of termochemical processes for improving surface mechanical properties. Boriding have been positioning as a one of the processes which report high performance in the improvement of mechanical properties (hardness and wear strength) as well as corrosion resistance on several alloy systems; i.e. ferrous and non ferrous alloys, [1]. It has been seen that paste boriding process can be used in high production lines in comparison with the powder‐pack boriding, [2]. On the other hand, surface treatment by nitriding can produce a set of high surface hardness and good wear resistance, [2]. However, it is not recommended to apply this treatment in some high carbon steels because the carbon tends to diffuse at the surface of the sample, and the nitride layer formed on the substrate leads to flaking and spalling when a mechanical load is applied. This study analyzed the production of multicomponential boro‐nitriding layers at the surface of 99.8% high purity iron by two stage process consisting of paste boriding step followed by a powder nitriding process. Characterization of the boro‐nitriding samples were made by Knoop microhardness testing, Energy Dispersive Spectroscopy (EDS), X‐ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Glow Discharge Optical Emission Spectroscopy (GDOES). The diffusion of boron and nitrogen in the two stage process depends of several factors, although in the boriding stage boron potential seems sensible to the preparation of boriding paste as well as the particle size. Additionally, the preparation of the sample before and after of boriding stage plays an important role because is possible to minimize surface imperfections and unnecessary compound on the surface after boriding stage. The product consist of a well define FexBy/BxNy/diffusion zone multicomponential layers which seems as a interesting system where a combination of wear and corrosion strength are main properties in service. [1] I. Campos, R. Torres, O. Bautista, G. Ramírez, L. Zúñiga., Appl. Surf. Sci. 252 (2006) 2396‐2403. [2] I. Campos, O. Bautista, G. Ramírez, M. Islas, J. De la Parra, L. Zúñiga., Appl. Surf. Sci. 243 (2005) 429‐436.
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SPECIAL SESSION: Microstructural Control Through Diffusion Processes ORGANISED BY: Prof. Dr. Yvan Houbaert University, BELGIUM Dr. Eng. Lucía Suárez CTM ‐ Technologic Centre, SPAIN Dr. Eng. Pablo Rodríguez CTM ‐ Technologic Centre, SPAIN
DSL047 Mrs. Yamina Lahmar‐Mebdoua Centre de Développement des Technologies Avancées, Algiers, Algeria
Heat Diffusion in Solidifying Alumina Splat Deposited on Solid Substrate under Plasma sprayed Conditions: Application to Coating Formation Y. Lahmar‐Mebdoua1, A. Vardelle2, P. Fauchais2 and D. Gobin3 1 Centre de Développement des Technologies Avancées, Algiers, Algeria,
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2 Sciences des Procédés Céramiques et de Traitement de Surface UMR‐CNRS 6638 Limoges University, France, 3 Laboratoire Fluide, Automatique, Systèmes Thermiques UMR‐CNRS 7608, Paris VI University, France A plasma‐sprayed coating is build up by the layering of individual splats. The latter are formed by the spreading and solidification of molten particles sprayed onto a solid substrate. The properties of coating depend on its microstructure and quality of contact between the splats and underlying layer and between the piled‐up splats [1]. This work deals with a 1D model of heat transfer between plasma‐sprayed alumina splats and smooth substrates. The model is based on the heat diffusion in the solidifying splat and substrate and includes undercooling phenomenon, heterogeneous nucleation and crystal growth kinetics [2,3]. It assumes that splat spreading and solidification are two independent processes. The model predicts the splat cooling and solidification taking into account, as far as possible, the in flight particle properties drawn from the literature in order to study their effect on the splat thermal history. The effect of the quality of contact between the splats as well as the already deposited and solidified layer thickness on the grain size distribution and front solidification velocity is investigated. [1] P. Fauchais, M. Fukumoto, A. Vardelle, and M. Vardelle, J.T.S.T, Vol. 13(3), p.337 (2004) . [2] Y. Lahmar‐Mebdoua, A. Vardelle, P. Fauchais and D. Gobin, J.H.T.M.P, vol. 11, p.191, (2007) [3] Y. Lahmar‐Mebdoua, A. Vardelle, P. Fauchais and D. Gobin, J.H.T.M.P, vol. 12, p.279 (2008) VIP‐DSL020 Prof. Y. Sohn Department of Mechanical, Materials and Aerospace Engineering University of Central Florida, Orlando, FL, USA
Determination of Average Ternary Interdiffusion Coefficients using Moments of Interdiffusion Flux and Concentration Profiles N. Garimella, Y.H. Sohn Advanced Materials Processing and Analysis Center Department of Mechanical, Materials and Aerospace Engineering University of Central Florida, Orlando, FL, USA We developed a method of rigorous solution of the Onsager’s flow equations using moments of the interdiffusion‐ parameter integrands for the determination of average ternary interdiffusion coefficients. The analysis developed by Dayananda and Sohn [1] is the basis for this refined approach. Average main and cross interdiffusion coefficients are determined over selected regions in the diffusion zone using the diffusion‐distance moments of the interdiffusion flux flow equations. Thermodynamic stability of solid solutions in the light of interdiffusion phenomenon is taken as validation criteria to identify accurate and reliable values of the ternary interdiffusion coefficients. Regulations are proposed for successful application of the analysis method to various ternary diffusion couples in Ni‐ and Fe‐based intermetallics. [1] M.A. Dayananda, Y.H. Sohn, Metall. Mater. Trans. A, 30A, 535 (1999). ……………… VIP‐DSL025 Prof. H. Fujikawa Air Water Incorporated., Japan
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Invited Talk (VIP‐DSL025) Effect of Small Amounts of Elements and Microstructure of Steels on High Temperature Oxidation Behaviour of Stainless Steels H. Fujikawa Air Water Incorporated, 1‐8 Nagahama‐cho Amagasaki‐shi Hyogo 660‐0091 Japan I review the effect of small amounts of elements and the microstructure of the steels on high temperature oxidation behavior of ferritic and austenitic stainless steels. In the ferritic stainless steels, the effect of C, N, stabilized elements of C and N, such as Ti, Nb, Zr, Ta and Hf, and the microstructure of the steels themselves on high temperature oxidation behaviour was studied. C and N showed extremely harmful effects, but the stabilized elements (Ti, Nb, Zr, Ta and Hf) showed good effects. Particularly, Zr, Ta and Hf showed remarkably excellent behavior. A strong relationship between the microstructure of the steels and the effect of these elements was apparent. That is, when austenitic phase precipitated at the exposed temperature, the abnormal oxidation was caused at the austenitic phase. Also, the oxidation resistance of ferritic stainless steels decreased with the increase of the precipitation of the austenitic phase at the exposed temperature. The steels precipitated at 20 to 50% of the austenitic phase showed the worst oxidation behavior. In austenitic stainless steels, the precipitation of MnS compound caused a harmful effect. The oxidation resistance of austenitic stainless steels was enhanced by decreasing S concentration in steels. Furthermore, the addition of a small amount of Y in austenitic stainless steels caused good oxidation behavior. I will explain the mechanism of these effects in detail. ……………… DSL153 Prof. RafaelColás Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, A.P. 149‐F, 66451 San Nicolás de los Garza, N.L., México
Diffusion in Electrodes Used for Resistance Spot Welding of Galvannealed Steel Maribel de la Garza1, Patricia Zambrano1, Martha P. Guerrero‐Mata1, Tamás Reti2, Mihaly Réger2, Imre Felde3 and Rafael Colás1. 1 Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, A.P. 149‐F, 66451 San Nicolás de los Garza, N.L., México. 2 Department of Materials Science and Technology, Banki Donat Faculty of Mechanical and Safety Engineering, Budapest Polytechnic, Hungary. 3 Bay Zoltan Foundation, Institute for Materials and Technology, Hungary. A study was carried out in Zr‐Cr bearing copper electrodes used for resistance spot welding of galvannealed steel strips. One electrode exhibited a series of well‐defined layers in which Zn diffused to form ß‐ and ?‐brasses; an external layer containing iron was detected in this electrode. Another electrode that exhibited a high degree of damage did not exhibited continuous Zn‐diffusion layers in all places, moreover, the Fe‐containing layer was either removed, or had it grown to a high extend in some places; the occurrence of Cu‐rich particles embedded within the Fe containing layer was observed. Multiple cracks were observed within the ? brass layer in both electrodes. The difference in the observed behaviour of the electrodes can be attributed to difference in the characteristics of the galvannealed coating of the strips, as the first electrode was used to weld strips in which the layer corresponding to the G phase was well developed, whereas the second electrode was used to weld strips with only
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an incipient layer. It can be concluded that growth of the G phase changes the thermophysical properties of the zinc coating, affecting the temperature profile during spot welding. Keywords: Diffusion, resistance spot welding, galvanneal, brass. ……………… DSL411 Dr. Alberto Monsalve G. Dpto. Ing. Metalúrgica, Ca silla 10233, Facultad de Ingeniería, Universidad de Santiago de Chile, Chile
Importance of Diffusion in the Continuous Annealing of Dual‐Phase Steels A. Monsalve1, F. Castro1, A. Artigas1, Y. Houbaert2 and R. Colás3 1Dpto. Ing. Metalúrgica, Ca silla 10233, Facultad de Ingeniería, Universidad de Santiago de Chile. 2Department of Metallurgy and Materials Science, University of Ghent, Bélgica 3Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, 66451 San Nicolás de la Garza, N.L. México. Continuous annealing Dual‐Phase steels have been studied in order to identify the different phases that are present in the steels after heat treatments consisting in continuous annealing at several times at a temperature of 800ºC. Previously, samples were submitted to a cold rolling process of 70%. In order to reveal the phases present in the steels, Le Pera reagent was used for differentiate martensite from ferrite and bainite. Optical, electronic and atomic force microscopy were used in order to study the phases present after each treatment. A salt furnace was used for heating the samples, with a heating rate of 50ºC/s, after which, water quenching was developed. It was found that the formation of austenite from ferrite is a diffusion‐controlled phase transformation [1]. At higher temperatures, the rate of transformation increases, due to the diffusion nature of the phenomena. As well, micro hardness measurements were used in order to identify phases, in those cases of phases with similar morphologies. [1] R. O. Rocha, T.M. Melo, E.V. Pereloma and D.B. Santos, Mat. Sci. Eng., A 391, 296 (2005). ……………… DSL180 Mr. Yuhki Tsukada Department of Materials, Physics and Energy Engineering, Graduate School of Engineering, Nagoya University, Nagoya 464‐8603, Japan
Phase‐Field Simulation on Coarsening of the γ’ Phase Particles in Ni‐Based Superalloys Considering Elastic Inhomogeneity Y. Tsukada1, Y. Murata1, T. Koyama2, M. Morinaga1 1Department of Materials, Physics and Energy Engineering, Graduate School of Engineering, Nagoya University, Nagoya 464‐8603, Japan. 2National Institute for Materials Science, Tsukuba 305‐0047, Japan.
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Ni‐based superalloys, which are composed of the γ’ phase precipitated in the γ phase, are applied to gas turbine materials because of their excellent mechanical properties such as creep strength at high temperatures. It is of great importance to control the volume fraction, morphology and size distribution of the γ’ phase in the (γ+γ’) two‐ phase microstructure, since the mechanical properties of the superalloys are strongly related to them. Although the elastic inhomogeneity between the γ and γ’ phases is about 13% in a practical Ni‐based superalloy at high temperatures [1], effect of the inhomogeneity on the microstructure evolution has been left unsolved. In this study, a phase‐field simulation was performed to examine the dependence of morphological evolution and coarsening kinetics of the γ’ particles on the elastic inhomogeneity in Ni‐based superalloys. On the basis of the elastic constants of a practical alloy [1], both elastic anisotropy and shear modulus were varied independently in the simulation. In the elastic energy calculation in this study, the model proposed by Hu and Chen [2] was adopted to solve the local displacement vector in the elastically inhomogeneous system. The variation of elastic anisotropy gave significant effect on both morphology and size distribution spectrum of the γ’ particles, whereas the variation of shear modulus gave little effect on them. Furthermore, as a result of a series of simulations, it was found that the coarsening rate constant of the cubic growth law depended on the standard deviation of the γ’ size distribution. [1] K. Tanaka, T. Kajikawa, T. Ichitsubo, M. Osawa, T. Yokokawa and H. Harada, Mater. Sci. Forum, 475‐479, 619 (2005). [2] S. Y. Hu and L. Q. Chen, Acta Mater., 49, 1879 (2001). ……………… DSL418 Dr. Pablo Rodriguez CTM‐ Technologic Centre, Av. Bases de Manresa, 1 08242 Manresa, Barcelona, Spain
Al‐Si‐Fe‐Intermetallics on Fe‐Substrates during Hot‐Dipping P. R. Calvillo 1, L. Suarez1 and Y. Houbaert 2 1 CTM ‐ Technologic Centre, Materials Technology Area, Av. Bases de Manresa, 1 E‐08242 Manresa, Barcelona, Spain 2 Department of Materials Science and Engineering, Ghent University, Technologiepark 903 B‐9052 Gent, Belgium. Steels alloyed with Si and Al are used as core material in flux carrying machines, they are commonly called electrical steels, divided in grain oriented and non oriented when a material without magnetic anisotropy or not is desiderated and used in transformer and electrical motors, respectively. The appearance of brittle ordered structures when Si+Al content in steel is above 4 m.‐% makes its industrial production not always easy. Therefore hot dipping in a Al‐Si bath followed by a diffusion annealing was found to be a production way of steels with high Si and/or Al concentration and to overcome the creation of fragile structures during deformation processes, as rolling. The formation of different layered Al‐Si‐Fe intermetallics on the steel substrate depends on among diverse processing parameters as bath temperature and composition, immersion time, preheated of the steel substrate and its composition and cooling down to room temperature. This contribution reports the solidification and diffusion Al‐Si‐Fe products obtained during hot dipping process in an Al iron saturated and a hypoeutectic Al – 5 m.‐% Si baths of ultra low carbon steel and Fe‐substrates with 3 m.‐% Si, annealed and cold rolled to different thickness. The preheating of the samples and bath temperatures were varied between 670 to750°C. Dipping times between 1 to 1000 sec. were applied. The different layers and compounds formed were characterised by Scanning Electron Microscopy (SEM), using the Back Scattered Electron (BSE) detector and Energy Dispersive Spectroscopy (EDS). Their obtained chemical composition allowed the comparison of the diffusion and solidification paths in the Al‐Si‐Fe equilibrium diagram.
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……………… DSL419 Dr. L. Suarez CTM‐ Technologic Centre, Av. Bases de Manresa, 1 08242 Manresa, Barcelona, Spain
Galvanized Coatings Produced in a Hot Dip Simulator (HDS) L. Suarez1, D. Warichet2 and Y. Houbaert3 1 CTM‐ Technologic Centre, Materials Technology Area, Av. Bases de Manresa, 1 08242 Manresa, Barcelona, Spain 2 Galva Power Group NV / Div. Galva Staal – ICA, B‐9200 Dendermonde, Belgium 3 Department of Materials Science and Engineering, Ghent University Technologiepark 903, B‐9052 Gent, Belgium Steel is still the main construction material for automobiles, general equipment and industrial machinery. For applications in aggressive atmospheres, the steel sheet has to be coated with a protective layer. Hot dip galvanizing has proven to provide excellent protection against corrosion of steel for a wide range of applications. Coatings of Zn‐Al alloys on steel sheet give a high corrosion resistance due to the corrosion prevention by zinc and the passivation by Al. Steel producers have developed advanced technologies for the continuous annealing and coating of steel sheet to meet the challenges of automotive and appliance manufacturers. Many important industrial processing steps, such as heating, soaking, cooling, aging, dipping, wiping and galvannealing require a reliable procedure for process verification. Verification on production or pilot lines is neither economical nor efficient. However, it is generally accepted that a laboratory scale process simulation is the most economical, efficient and reliable verification method. Simulators for the HDP (Hot Dip Process) have been commercialized: they allow laboratory scale simulations of the (hot dip) coating and of the consequent annealing processes occurring in industrial production lines, serving for process and product improvement and development. The complete HDGP involves many variables that can impact on the appearance and characteristics of the final coated product. To improve and further develop the production and the final coating properties, hot dipping experiments are performed in a HDP simulator using different substrates, bath compositions and hot dipping parameters. Surface layers are characterised by SEM and EDX‐EDS. The results obtained by these simulations are transferable to the production process of real continuous galvanizing lines. Important industrial steps of the process can be simulated in the HDPS with a high variability of parameters (i.e. gas atmosphere, humidity, heating and cooling rates, immersion/extraction speeds, temperatures). The material consumption is extremely small compared with pilot or production lines and production capacities do not need to be used. ……………… DSL174 Dr. M. P. Guerrero Mata Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ave. Universidad S/N, San Nicolás de los Garza, N.L., 66451 México
Development of Intermetallic Phases on Fe‐Zn Coatings M. de la Garza1, M. Moreno1, R.Colás1, Y. Houbaert2 and M.P. Guerrero‐Mata1 1 Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, DSL‐2009 / Rome ‐ ITALY ABSTRACT BOOK
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Ave. Universidad S/N, San Nicolás de los Garza, N.L., 66451 México. 2Department of Metallurgy and Materials Science, University of Ghent, Technologiepark 903, 9052 Gent, Belgium. Fe‐Zn coatings are obtained by a heat treatment after galvanizing the steel, as these coatings have improved properties over the traditional galvanized ones. In this work various conditions were studied in order to improve the iron diffusion into the zinc layer to achieved better coating adhesion as well as a proper phase distribution. The coating (Fe‐Zn) formation was studied on a high strength low alloy steel (HSLA), this was carried out comparing the microstructures and Fe contents on the phases present of samples coated in a industrial plant and in samples coated in a laboratory hot dip process simulator. Three chemical compositions of bath were used, annealing temperature and dwell time were varied. The adhesion was measured by V bending test at 60 and 90º. It was found that the most influencing parameters on the phase formation of the coating were temperature and time of annealing. Keywords: HSLA steel, galvannealing, phase formation. ……………… VIP‐DSL059 Prof. Ivan Houbaert Ghent University, BELGIUM
Copper Penetration during the Oxidation of Cu‐bearing Steel Yvan Houbaert1, Jan Penning1, Ivonne Infante Danzo1 Department of Metallurgy and Materials Science, Ghent University Technologiepark 903, B‐9052 Gent, Belgium Cu‐bearing steel presents some advantages: solid solution strengthening, increased hardenability, possible precipitation hardening, increased resistance to atmospheric corrosion (hence the name “weathering steels”), but on the other hand Cu‐additions to steel can be considered as a contamination of the steel scrap, as it will not be easily removed during metallurgical processing. Furthermore, during slab reheating problems of “surface hot shortness” may occur, due to the penetration of liquid Cu between the austenite grains, followed by cracking during the rolling process. Steel samples with Cu‐contents between 0,4 and 1,8 wt.‐% Cu and variable additions of alloying elements (Al, Mn, Mo, Cr, Si and Ni) were oxidized at 900 and 1100°C and the morphology and degree of Cu‐penetration was evaluated by metallographic observation. It was shown that the addition of Al has no influence on the Cu‐ penetration, that Mn and Mo increase the penetration, Cr affects the penetration of Cu indirectly, determining the quantity of Cu expulsed from the steel, certain combinations of Cr/Si enhance the penetration, Si also enhances the penetration and modify the oxidation mechanism. Finally, it was observed that nickel reduces the tendency to surface hot shortness and modifies completely the oxidation and penetration patterns. Explanations on the behavior of the alloying elements are given in terms of a modification of the surface tension between the molten copper and the metal surface, visible in a modification of the dihedral angle between the phases. ……………… DSL111 Prof. E. A. Pastukhov Institute of metallurgy, Russian Academy of Sciences, UrD. Yekaterinburg, Russia
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Molecular Dynamic Calculation of the Hydrogen and Iron Diffusion in the molten Tantalum under Electric Field E.A. Pastukhov, A.A.Vostrjakov, N.I.Sidorov, V.P.Chentsov Institute of metallurgy, Russian Academy of Sciences, UrD. Yekaterinburg, Russia. High purity Tantalum producing is defined by the choice of refinement technology nowadays, and, as consequence, depends on impurity structure in Tantalum melt. As authors [1] had proved, Tantalum processing by Hydrogen stream in remelting processes with external electric field applying is one of the perspective refinement methods. Efficiency increase of the Tantalum melt refinement from impurities by means of its processing in Hydrogen stream remains an actual problem. Therefore Hydrogen behavior in Tantalum and mechanism of electric field influence to Hydrogen and other impurity atoms diffusion in the Tantalum melt are under interest of the researches. Molecular dynamics (MD) method for analysis of electric field intensity affect to the Iron impurities removal from Tantalum under Hydrogen presence is used in this work. Radial distribution functions and diffusion factors of Hydrogen and Iron atoms in Tantalum melt at 3400K under electric field and without it are obtained. It is proved, that electric field imposing on liquid Tantalum with Iron impurity increases Tantalum diffusion factor by more, than two power of value: from 1,7∙10‐4 to 3,6∙10‐2 cm2 ∙c‐1 while the Iron atoms diffusion factor increases approximately three times: 1,3∙10‐5 to 3,2∙10‐5 cm2 ∙c‐1. Hydrogen introduction into the MD ‐ cell without electric field imposing gives much low increase of Tantalum diffusion factor: from 1,7∙10‐4 to 7,4∙10‐4 cm2 ∙ c‐1, but more considerable growth of those for Iron: from 1,3∙10‐5 to 1,5∙10‐4 cm2 ∙ с‐1. Simultaneous imposing an electric field and Hydrogen introduction into the MD – cell keeps Tantalum and Iron diffusion factors at the level of electric field affect. Thus electric field imposing affect is a main parameter of Iron diffusion factor increasing. [1] D. Elanski, K. Mimura, T. Ito, M. Isshiki. Materials Letters, 30, 1, (1997). ……………… DSL219 Prof. Galina Zmievskaya M.V.Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, 125047 Moscow, Miusskaya sq.4, Russia
Diffusion Stochastic Processes Models and Solids Damaging Effects A.L. Bondareva, G.I. Zmievskaya M.V.Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, 125047 Moscow, Miusskaya sq.4, Russia. Computer simulation of radiation stimulated defects into solids deals with beams of radiation when only the absolute number of ionizing particles or photons interacting with the object is important. Damaging effects into solid body are caused to laser‐matter interaction have a character of blistering (or vacancy‐gaseous defects formation), which is considered as the heterogeneous first‐order phase transition at non‐equilibrium stage[1]. The peculiarities of radiation defects clustering: alteration of microstructure in conditions of impacts of pulse fluxes of IR or porosity into thin metal layers, formation of lattice tension within "barier" layer into metal mirrors (multilayer) structure are to be discussed in terms of statistical mechanics, kinetic theory and stochastic dynamics. The both: Fokker‐Planck‐Kolmogorov and Smolukhovskii equations have been used for sophisticated treatment of non‐linear brownian migration of clusters with alternating masses into lattice. The models of nonlinear stochastic diffusion into the both: phase space of clusters sizes and phase space of its Cartesian coordinates are examined. New kind of self‐organization phenomena due to long‐range indirect elastic interaction between defects can be
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added to the accounting of the internal interfaces with sources or sinks of the vacancies and the blisters. We put here the main attention focuses on the kinetic description of defects formation under condition of many interfaces between follow metal and dielectric layers. The work is partially supported by grants RFBR. [1] G.I. Zmievskaya//in book"Dynamics of Transport in Plasmas and Charged Beams", eds. G. Maino and M.Ottaviani(Singapore:World Sci. Publ.), 1996, p.84‐98 ……………… VIP‐DSL020 Prof. Y. Sohn Advanced Materials Processing and Analysis Center and Department of Mechanical, Materials and Aerospace Engineering, University of Central Florida, Orlando, FL 32816
Effects of Combined Surface Modification on Adhesion Strength of CrN Coatings for STS420 G.C. Jeong1, H.J. Choi2, Y.H. Sohn2, S.I. Kwun3 1 Department of Advanced Materials Engineering, Korea Polytechnic University, Shihung 429‐ 793, Republic of Korea 2Advanced Materials Processing and Analysis Center and Department of Mechanical, Materials and Aerospace Engineering, University of Central Florida, Orlando, FL 32816 3Department of Materials Science and Engineering, Korea University, Seoul 136‐701, Republic of Korea. In order to improve the durability and performance of molds and tools, diverse methods of surface modification are used where the adhesion strength between a substrate and coating plays an important role. To improve adhesion strength, a combined surface modification method is often utilized. In this study, adhesion strength and microstructure of various combined surface modifications (i.e., ion‐nitriding, Cr intermediate layer, CrN layer and nitrogen ion‐implantation) were examined on STS420. Phase constituents, microstructure, adhesion strength and hardness of coating‐substrate system with combined surface modification was examined by using optical microscopy, X‐ray diffraction, transmission electron microscopy, scratch test, and nano‐indentation. Highest adhesion strength was observed when CrN coating was formed by Nitrogen implantation on ion‐nitrided substrate with a Crintermediate layer. Influence of processing sequence and combination is related to microstructural observations and adhesion strength. ……………… DSL163 Mrs. Hamideh Kafash Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran
Effect of Homogenization variables on Microstructure in Ti‐57.5%wtNi Alloy H.kaffash1, A. Shokuhfar2, P.Movahed1, H. Tavakoli3 1Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran. 2Faculty of Mechanical Engineering, K.N. Toosi University of Technology, P.O Box: 19395‐1999, Tehran, Iran.
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3Advanced Material Research Center, Tehran, Iran. It is widely recognized that improvements of shape memory and mechanical properties in NiTi alloys are achieved by thermomechanical and aging treatment. Especially, the aging treatment is an effective process in Ni‐rich NiTi alloys due to precipitation strengthening from the homogenized parent phase. In this study, NiTi alloy with high nickel content, corresponding to Ti‐57.5%wt Ni, was prepared by vacuum induction melting in a graphite crucible. The homogenization heat treatments were conducted in NiTi single phase region (1100OC) and for various times (0.5, 1, 2, and 4 hours) and then samples were cooled in two different media (furnace and air). Microstructural investigations were carried out by optical microscope and scanning electron microscope (SEM) equipped with an energy dispersive X‐ray (EDX) analysis. It was seen that increasing the time of homogenization results in finer precipitations and uniform distribution of them. In addition, types and locations of precipitated phases were correlated to the cooling media and time of homogenization. Furthermore, changing the rate of cooling shows a great effect on the hardness of samples. [1] Y. Motemani, et al., J. Alloys Compd, 17517 (2008), [2] D. Holec, O. Bojda, A. Dlouhy, J.msea, 481‐482, 462,(2006) ……………… DSL164 Mr. Pooria Movahed Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran
Effect of Homogenization Time and Cooling Rate on Martensitic Transformations in Ti‐57.5%wtNi Alloy P.Movahed1, A. Shokuhfar1, H.Kaffash1, A. Etaati1, H.Bolvardi1, H. Tavakoli2 1Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran 2Advanced Material Research Center, Tehran, Iran The NiTi alloys containing more than 55%wt nickel undergo precipitation of Ni4Ti3, Ni3Ti2, and Ni3Ti phases during various heat treatments which could have a great effect on the chemical composition of the matrix and behaviour of alloy. These precipitations have a considerable effect on subsequent martensitic transformations and also on hardness. In this investigation, NiTi alloy with Ti‐57.5%wt nickel content was produced by vacuum induction melting in a graphite crucible. The samples were subjected to the homogenization heat treatments which include heating to the NiTi single phase region (1100OC) and keeping for various times (0.5, 1, 2, and 4 hours). The subsequent cooling was conducted in different cooling media (furnace and air) in order to obtain different precipitations. Microstructural investigations were carried out by optical microscope and scanning electron microscope (SEM) equipped with an energy dispersive X‐ray (EDX) analysis. It was seen that Ni4Ti3 particles with a bimodal size distribution are formed during slower cooling rate. Differential scanning calorimetry (DSC) was used to investigate the effect of cooling rate on transformation temperatures. This test clearly showed the correlation between precipitations type and transformation temperatures of the alloy. [1] L.J. Chiang et al, J. Alloys Compd, 458, 231–237(2008) [2] M. Peltonen et al, J. Alloys Compd, 460, 237–245(2008) ……………… DSL165 Mr. Emad Omrani
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Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran
The Effects of Annealing Time and Cooling Environment on Microstructure and Transformation Temperatures of Ni‐42.5wt%Ti‐7.5wt%Cu Alloy E. Omrani1, A. Shokuhfar1, A. Etaati1, A. Dorri M.2, A. Saatian3 1Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran. 2Department of Materials Science and Engineering, Sharif University of Technology, Tehran, Iran. 3Department of Metallurgy and Materials, Faculty of Engineering, University of Tehran, Tehran, Iran. The present paper deals with different effects of annealing time and cooling environment on Ni‐42.5wt%Ti‐ 7.5wt%Cu alloy. The alloy was prepared by vacuum arc melting. Afterward three annealing times (half, one and two hour) and tree cooling environments (water, air and furnace) at 1373 K were selected. Optical and Scanning Electron Microscopic methods, EDX, Differential Scanning Calorimetery and hardness tests have been used to evaluate the microstructure, transformation temperatures and hardness data. Microscopic results illustrate that specimens cooled in water and air are super‐saturated. Also microstructure in furnace cooling has many disparities with the other cooling environments’ microstructure and two types of precipitates exhibits in the matrix, but in other cooling environments, only one phase can be observed. The Ti(Ni,Cu)2 particle phase are distributed in the matrix in all of the microstructure irrespective of cooling rate. Observations show that increasing the time of annealing results in finer precipitations and uniform distribution in the matrix. In addition, hardness increases by increasing of annealing time in water and air cooling environment although extremely decline by increasing of annealing time in furnace cooled specimens. Also increase in hardness is observed as the cooling rate is increased in an equal annealing time. To study transformation temperatures, DSC results indicate that there is no peek in water and air cooling environment while in furnace cooled specimens, peeks was observed. [1] M. Nishida, T. Ueda, Y. Toyama and A. Chiba, Material Science Forum, 56‐58, 599 (1990) ……………… DSL211 Mr. Amir Etaati Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran
Study on Homogenization Time and Cooling Rate on Microstructure and Transformation temperatures of Ni‐42.5wt%Ti‐3wt%Cu alloy A. Etaati1, A. Shokuhfar1, E. Omrani1, P.Movahed1, H.Bolvardi1, H. Tavakoli2 1Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran. 2Advanced Material Research Center, Tehran, Iran. Over the last decades, numerous investigations have been conducted on Nitinol properties. However, the effects of alloying elements on Ni‐rich NiTi alloys have been considered less. In this research, different effects of homogenization time and cooling rate on behaviors of Ni‐42.5wt%Ti‐3wt%Cu alloy were evaluated. The mentioned alloy fabricated by vacuum arc melting method. Three different homogenization times (half, one and two hours) and three cooling media (water, air and furnace) were selected. The microstructure, martensitic transformation temperatures and hardness were examined by means of optical and scanning electron microscope (SEM) equipped with an energy dispersive X‐ray (EDX) analysis, differential scanning calorimetry (DSC) and hardness test, respectively. According to the microscopic investigations, no significant changes were observed after half an hour.
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However, results indicate that increasing time of homogenization leads to finer precipitations and uniform distribution of them. The various Cooling environments result in formation of two types of precipitation phases. It was seen that in high cooling rate, majority of precipitations are consisted of Ti2(Ni,Cu) while by decreasing cooling rate NiTiCu precipitates are appeared too, which affect the hardness. [1] T.Nam, J.Lee, G.Cho and Y.Kim, Materials Science and Engineering, 438–440, 687–690 (2006) [2] T.Nam, J.Lee, J.Nam, K.Kim, G.Cho and Y.Kim, Materials Science and Engineering, 483–484, 460–463(2008) ……………… DSL442 Mr. Seyed Majid SAFI Islamic Azad University of Ahvaz, Ahvaz , Iran
A New Modified Austempering to Increase Strength and Ductility Simultaneously for UHS Steels S.M. Safi 1, M.K. Besharati Givi2 1Islamic Azad University of Ahvaz, Ahvaz , Iran. 2University of Tehran,Tehran,Iran. In this paper, a modified up‐quenching heat treatment method to the ASSAB 705M steel (ultra high strength steel) is proposed. A low alloy steel (0.33%C), was used to study the effect of isothermal austempering, successive austempering and modified up‐quenching austempering heat treatment on the mechanical properties. The specimens, were cut from a bar with 25mm diameter and after achieving the best temperature and time of austenitizing, austenitized at for 60 min and followed by quenching at for the high austempering temperature to achieve the upper bainite morphology and at for the lower austempering temperature to achieve the lower bainite morphology. In the case of successive austempering, the specimens were first austempered at for different periods (500sec. and 60sec.) and then austempered at for 1000 sec to achieve the mixed structure of upper bainite and lower bainite morphology. The specimens selected for up‐quenching, after austenitization were quenched to below ( ) for 120 sec. followed by heating at to achieve the mixed structure of tempered martensite and lower bainite and to achieve the mixed structure of tempered martensite and upper bainite for 1000 sec. The all of processes were performed in the salt bath furnaces. Experimental results are presented and the advantages of the modified method are discussed. As well, it is shown that the best combination of strength and ductility can be achieved by the proposed heat treatment method. This modified method, can offer techniques that simultaneously improve not only strength 12 %( compare with results of strength after other heat treatment methods), but also ductility 38 %( compare with results of ductility after other heat treatment methods). While, conventional heat treatment of ultra high strength steels (UHSS) cannot always meet the strict engineering requirements for improved strength and ductility simultaneously. It has been shown that the mixed structure of tempered martensite and lower bainite that has been suggested in this investigation offers a good combination of strength and ductility. ……………… DSL321 Prof. Changwoo Lee Advanced Welding and Joining Technical Service Center, Korea Institute of Industrial Technology, 7‐47 Songdo‐Dong, Yeonsu‐Gu, Incheon 406‐840, Korea
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Effect of SiC Nanoparticels Dispersion on the Microstructure and Mechanical Properties of Electroplated Sn‐Bi Solder Alloy 1C. W. Lee, Y. S. Shin, and S. H. Yoo 1Advanced Welding and Joining Technical Service Center, Korea Institute of Industrial Technology, 7‐47 Songdo‐ Dong, Yeonsu‐Gu, Incheon 406‐840, Korea The effect of SiC nanoparticle dispersion was investigated for microstructure change and mechanical properties of Sn‐Bi electroplated alloys. The diameters of SiC nanoparticle in this study were 45‐55nm. The SiC nanoparticles were mixed with Sn‐Bi electroplating and then the nanoparticles were dispersed with ultrasonic vibrator. After the dispersion, the SiC dispersed Sn‐Bi alloys were electroplated on Cu deposited Si wafer. The microstructure and mechanical properties of the sample were evaluated by FE‐TEM, FE‐SEM, EDS, and shear tester. For TEM observation, the specimens were prepared by ultramicrotome and FIB. The SiC nanoparticles were well‐dispersed in Sn‐Bi alloy. SiC particles were located near grain boundaries or grain inside. The average grain size of the solder alloy was decrease about 30% compared with the grain size of Sn‐Bi alloy prepared in the same condition. Due to the grain refinement and dispersion hardening by SiC nanoparticles, the SiC dispersed Sn‐Bi alloy is expected to obtain high reliability and joining strength when it applied to interconnection materials. ……………… DSL011 Dr. Iulia‐Mirela Britchi Romanian Academy, Institute of Physical Chemistry "Ilie Murgulescu", Bucharest, ROMANIA
Surface Properties of 316L Austenitic Steel Improved by Simultaneous Diffusion of Titanium and Aluminium I. M. Britchi1, N. Ene1, M. Olteanu1, E. Vasile2 and P. Nita2 1 Romanian Academy, Institute of Physical Chemistry “Ilie Murgulescu”, Splaiul Independentei, 202, Bucharest, ROMANIA 2 METAV – Research and Development, Bucharest, ROMANIA Samples of 316L austenitic steel were submitted to a thermochemical treatment which implies a surface diffusion of Al and Ti. The technique of pack cementation with NH4Cl as activator was employed. The powder mixture was made of: aluminium, titanium, aluminium oxide and ammonium chloride. The same ratio of Al : Ti = 1 : 5 was used in all experiments. The variables were temperature and time. As a function of these parameters, diffusion layers of different thicknesses were obtained. Thermochemical treatment by pack cementation technique needs high temperatures, over 900°C. The samples were analysed by optical microscopy, Fig. 1, electronic microscopy, X‐ray diffraction, Vickers microhardness trials and corrosion tests. All layers were formed by a diffusion with reaction and present two zones with different structure and composition and therefore, different properties. Fig. 1. Optical micrographs of a cross section of diffusion layer – 316L austenitic steel substrate; with metallographic attack.
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References [1] Z. D. Xiang and P. K. Datta, Mater. Sci. Technol., 22, 10, 1177 (2006). [2] R. Bianco, M. A. Harper and R. A. Rapp, J. Metals, Nov. 68 (1991). [3] M. Britchi, N. Ene and M. Olteanu, J. Optoelectron. Adv. Mater., 10, 8, 2159 (2008). ……………… DSL025 Mr. Mohammad Sadeghi Material scince and Metallurgical Islamic Azad University, Karaj Branch, Iran
Improving Mechanical Properties of Ductile Cast Iron by Continuse Heat Treatment and Tin Trace Element M.Sadeghi1‐ H.Sabet1 ‐ M.Abbasi1 1 Material scince and Metallurgical Islamic Azad University, Karaj Branch P.o.Box:31485‐313.Fax:0261‐ 4418156. E.Mail:
[email protected] In this study the effect of continuse heat treatment and alloying of trace amount of tin on microstructure and mechanical properties of ferritic‐pearlitic ductile iron has been investigated. Two standard Y‐block was designed by in‐mold process. [1] Calculations and simulation were done before moulding by the Sutcast software. In each experiment, different chemical analysis were applied.The cooling curve of solidification was recorded by the datalogger with labview software and using S‐thermocouple (Pt‐Rh) attached into the mold. Then Y‐block was shakout from molds and cooled in the air. Standard speciemen were machined for doing mechanical and metallographic exams.The metallographic exams indicate that with increasing the rate of shakout time, the amount of pearlite in microstruture has been increased. [2] The mechanical testing illustrated that with increase the rate of shakout time, hardness and tensile strength have been increased, although the percentage of elongation and impact energy have been decreased. [3] [1] F.R.Juretzko ,J.Hitchings and D.M.Stefanesu, AFS Trans., Vol.115,p 046,IL USA, (2007) [2] G.M.Goodrich and R.W.Lobenhofe, AFS Trans., Vol.115, p 045,IL USA, (2007) [3] G. F. Vander Voort, Atlas of T.T Diagrams for Irons and steels, V.Flint ASM Internatinal, USA,p755, (1991) ……………… DSL121 Mr. Rasool Salekrostam Department of Mechanical Engineering, University of Tehran, Tehran, Iran
Enhanced Mechanical Properties of Stainless Steel 316L Via friction stir processing R.SalekRostam*1, M. k. Besharati Givi2
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1M.Sc student, Department of Mechanical Engineering, University of Tehran, Tehran, Iran,
[email protected] 2Associate Professor, Department of Mechanical Engineering, University of Tehran, Tehran, Iran,
[email protected] Friction stir processing is a solid state process to modify microstructure and mechanical properties of sheet metals and as‐cast materials. Friction stir processing is based on the friction stir welding (FSW) technique which was invented by The Welding Institute (TWI) in 1991 [1]. FSP composites usually consist of four different regions: (a)unaffected base metal;(b)heat affected zone(HAZ);(c)thermo‐mechanically affected zone (TMAZ) and (d)friction stir processed (FSP) zone. The regions are affected by the material flow behavior under the action of rotating non‐ consumable tool. However, the material flow behavior is predominantly influenced by the FSW tool profile, FSW tool dimensions, and FSW process parameters [2, 3]. In this process stirring action of the tool causes the material to intense plastic deformation that yields a dynamical recrystallization. In this study the effect of FSP and process parameters on microstructure and hardness of stainless steel 316L has been investigated. Also by using of FSP, composite layer of SiC/316L has been produced. Results show that, FSP leads to finer and homogenized grain structure, as well as increased hardness of material. The composites produced by FSP have uniformly distribution of SiC particles between the grains of base metal. Keywords: Friction stir processing, Microstructure modification, Stainless steel, Hardness, MMC References [1] Thomas WM, Nicoholas ED, Needham JC, Church MG, Templesmith P, Dawes CJ. GB patent application 9125978.8, December 1991; US patent 5460317, October 1995. [2] Yingchun Chen, Huijie Liu, Feng Jicai, Mater. Sci. Eng. A 420 (2006) 21–25. [3] H.J. Liu, Y.C. Chen, J.C. Feng, Scripta Mater. 55 (2006) 231–234. ……………… DSL167 Dr. Hyeon‐Taek Son Korea Institute of Industrial Technology, 1110‐9 Oryong‐dong, Buk‐gu, Gwangju, 506‐824, South Korea
Effects of RE Additions on Grain Refinement and Texture of Hot Extruded Mg‐Al‐Ca Based Alloys Hyeon‐Taek Son1, Dae‐Guen Kim1, Seul‐Ki Park1, Young‐Mo Kim1, Jae‐Seol Lee1 , Chang‐Seog Kang1 1Korea Institute of Industrial Technology, 1110‐9 Oryong‐dong, Buk‐gu, Gwangju, 506‐824, South Korea Magnesium alloys are attractive for many engineering structural application owing to their low density, high specific strength and easy‐recycling. However, the use of magnesium wrought alloys in industrial applications is still limited due to their lower strength and formability compared to other lightweight materials such as aluminum. It is well known that micro‐alloying elements can improve the thermomechanical processing ability as well as the mechanical properties of materials. The Mg–Al–Ca alloys contain thermally stable intermetallic compounds such as Al2Ca, Mg2Ca or (Al,Mg)2Ca, which preferentially exist at the grain boundaries of the Mg‐based solid solution in ingots [1,2]. These phases are typically brittle and coarse, thereby tending to debond from the magnesium matrix during plastic deformation. For this reason, the workability of the Mg–Al–Ca alloys is rather poor. Plastic working, however, can improve the formability by effectively decreasing grain size and fragmenting coarse compounds into small particles. The limited room temperature formability of Mg alloys prevents the wider diffusion of this metal for applications that would considerably benefit from its low density. The sharp texture typically seen in wrought products plays a large role for the room temperature formability [3]. Among various approaches attempted to weaken the texture, rare‐earth (RE) alloying element additions are quite promising [3, 4]. In this study, the
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microstructure behavior (grain refinement, intermetallic compound formation and texture evolution) of hot‐ extruded alloys with different RE additions (RE= Y, Nd or Sm) is investigated. [1] H. Hu, R. Shang, N. Li, AFS Trans. 111 (2003) 1019. [2] A. Suzuki, N.D. Saddock, J.W. Jones, T.M. Pollock, Scripta Mater. 51 (2004) 1005. [3] J. Bohlen, M.R. Nurnberg, J.W. Senn, D. Letzig, S.R. Agnew, Acta Mater. 55 (2007) 2101. [4] E.A. Ball, B. Prangnell, Scripta Metall. Mater. 31 (1994) 111. ……………… DSL221 Dr. ABDI Said Département de Science des Matériaux FGMGP, USTHB, BP32, El‐ Alia, Bab Ezouar, Alger, Algerie
Interaction Mechanism of Copper Matrix and Particles Stainless Steel in the Composite Cu /Steel 1Département de Science des Matériaux FGMGP, USTHB, BP32, El‐ Alia, Bab Ezouar, Alger, Algerie The materials of copper alloys have a nice appearance and are widely used as engineering materials in the electrical industry because of their high corrosion resistance, high electrical and thermal conductivity. However, it has a low mechanical and tribological resistance. For that we prepared by sintering a series of copper alloy reinforced with stainless steel particles at different proportion. The results of microstructure analysis and phase relationship with the mechanical tests were used to understand the mechanisms of interaction matrix reinforcement of new composite Cu / steel Keywords: Sintering, Metallic, Matrix, Composite, Copper/ stainless steel ……………… DSL277 Dr. Sandra Giacomin Schneider University of São Paulo‐USP, EEL‐DEMAR, Lorena, São Paulo, Brazil
Effect of Different Heat Treatment Conditions on Microstructure and Mechanical Properties of the Ti‐41Nb‐7Zr Biomedical Alloy S.G. Schneider1, J.A. Hayashi1, S. Schneider1 1University of São Paulo‐USP, EEL‐DEMAR, Lorena, São Paulo, BR. Titanium based alloys have been widely study as biomaterial due to their biocompatibility, corrosion resistance and low elastic moduli. One of the more important biomedical titanium alloys, in the late years has been the Ti‐ 6Al‐4V, however, account of the toxicity of the elements Al and V, new alloys that not contain these elements are achieving a great attention [1‐3]. And tissue reactions studies have identified Ti, Nb, Zr and Ta as non‐toxic elements as they do not cause any adverse reaction in human body [1‐3]. Furthermore, Nb and Ta are found to reduce the elastic modulus when alloyed with titanium in certain preferred quantities [3‐4]. In recent years there has been a significant development of novel implant alloys based on β Ti such as Ti–Nb–Zr and Ti–Nb–Zr–Ta alloys systems because processing variables can be controlled to lead selected results [1‐2].
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The purpose of the present work was to study the microstructure and mechanical properties of the Ti‐41Nb‐7Zr alloy at different heat treatments conditions. This alloy has been produced by arc melting under argon atmosphere. All ingots were submitted to sequences of heat treatment (1200ºC/24h and water quenching), cold working by swaging procedures and other heat treatment (both 1200ºC/2h and water quenching, or 500°C/2h and water quenching conditions). The microstructures, in as cast and heat‐treated condition, were examined by light microscopy, X‐ray diffraction, Vickers hardness tests. The mechanical characterization was evaluated through uniaxial tensile tests. These results shows that Ti‐41Nb‐7Zr alloy exhibit a lower modulus than that of conventional Ti alloys and the other mechanical properties are suitable for biomedical applications. [1] X. Tang, T. Ahmed, H.J. Rack, J. Mater. Sci. 35, 1805 (2000). [2] L.M. Elias, S.G. Schneider, S. Schneider, H.M. Silva, F. Malvisi, Mater. Sci. Eng. A 432, 108 (2006). [3] M. Geetha, A.K. Singh, K. Muraleedharan, A.K. Gogia, R. Asokamani, J. Alloys Compd. 329, 264 (2001). [4] Y. L. Zhou, M. Niinomi, T. Akahori, Mater. Sci. Eng. A 371, 283 (2004). ……………… DSL305 Prof. Maria Helena Robert University of Campinas, Brazil
Phase Transformations during Thixoforming of ASTM A536 60‐4‐18 Nodular Cast Iron M.H. Robert1, R. Cristofolini2 1University of Campinas, SP, Brazil. 2 Univille, Joinville, SC, Brazil. The potential ability of a certain alloy for thixoforming must gather some criteria such as its solidification range, the liquid fraction at eutectic temperature, and the sensitivity of liquid fraction with temperature [1]. Results so far have determined the thixoability of several families of Al alloys [2]; however, given the more recent application of the semi‐solid technology for ferrous alloys, a little has been done to establish the thixoability of such family of alloys and to understand phase transformations during thixoprocessing. Particularly for cast irons, very little information can be found in the specialized literature, in spite of the importance of such family of alloys and the potential advantages of using semi‐solid technology for their processing. This work investigates phase transformations during thixocasting ASTM A536 60‐40‐18 nodular cast iron, which finds commercial application in the automotive industry as several cast components. Initially thixoability evaluation is made through thermal analysis by DSC test and via thermodynamic simulation using commercial Thermocalc software. Liquid fraction sensitivities with temperature (dFl/dT) are determined, and thixoforming windows are suggested. Results indicate that a thixoforming window in the order of 20C is available; in this range an eutectic transformation takes place and the liquid fraction can be controlled. Thixotropic slurries were produced and resulting microstructures were analysed by OM, MEV, XRD and EDS microanalysis to discuss phase transformations taking place. Results show the feasibility of producing thixotropic semi‐solid of the studied cast iron, in spite of its narrow thixoforminhg window. Graphite nodules are strongly affected by heating and processing control must be rigid to avoid their excessive dissolution. [1] D. Liu, H.V. Atkinson and H. Jones, Acta Materialia, 53, 3807 (2005). [2] J. Lecomte‐Beckers, A. Rassili, M. Robelet, C.Poncin and R.Koeune, in Proceedings of the 9th International Conference on “Semi‐solid Processing of Alloys and Composites”, Busan, 2006, p.55. ……………… DSL345
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Dr. Jae‐Seol LEE Korea Institute of Industrial Technology, 1110‐9 Oryong, Buk‐gu, Gwangju, 500‐480, Korea
Microstructure and Texture Control of Cross Rolled AZ31 Mg Alloy Sheet Jae‐Seol LEEa, Hyeon‐Taek SON, Ki‐Yong LEE, Soon‐Sub Park Korea Institute of Industrial Technology, 1110‐9 Oryong, Buk‐gu, Gwangju, 500‐480, Korea aCorresponding author:
[email protected] The applications of Mg alloys in automobile and aerospace industries are increasing progressively. This is because of their low densities and their excellent properties such as heat dissipation, damping, electro magnetic shielding and recycling. However, due to the hcp structure and low stacking fault energy of magnesium, Mg alloys only have three independent active slip systems at (0001) basal plane, far below the five independent slip systems required for homogeneous deformation. As a result, formability of Mg alloy sheets at room temperature is rather poor, which greatly restricts their wide use in industrial applications. It is reported that Mg alloys shows excellent formability at high temperature. The microstructure and mechanical properties of Mg alloys are highly dependent on their primary processing such as cross rolling, different‐speeds‐rolling (DSR), equal channel angular pressing (ECAP) and equal channel angular extrusion (ECAE). In particular, cross rolling is expected to improve the grain refinement, mechanical properties and formability. Thus, it is well known that fine‐grained magnesium alloys show super‐plasticity in a low strain rate range at elevated temperature. The roll of cross rolling was tilted by 2.5o – 10o against TD in the RD–TD plane, comparing to normal rolling. In this study, the relationship between the deformation processes and the elongation characteristics at elevated temperature is investigated by tensile tests for the cross rolled AZ31 Mg alloy sheets. ……………… DSL449 Dr. M. Mosallaee Pour Materials and Mineral faculty, Yazd University, Iran
Microstructure‐Mechanical Properties Relationship in TLP Bonded IN‐ 738LC/BNi‐3/IN‐738LC Samples M. Mosallaee1, A. Ekrami2, K. Ohsasa3 and K. Matsuura4 1‐ Assistance professor, Materials and Mineral faculty, Yazd University, Iran. 2‐ Professor, Materials Faculty, Sharif University of Technology‐Iran. 3‐ Professor, Akita UniversityUniversity‐ Japan. 4‐ Professor, Graduate School of Engineering, Hokkaido University‐Japan. High content of g’ promoting elements in the chemical composition of IN‐738LC reduces significantly weldability of this nickel‐base superalloy [1, 2]. In the current research, effect of TLP bonding temperature on the developed micro‐constituents in the TLP bonding area was investigated. A critical bonding temperature (Tcr) was defined for TLP bonding of IN‐738LC/BNi‐3/IN‐738LC samples. Optical and Scanning electron microcopies were utilized for microstructural studies. WDS‐EPMA analysis accompanied with transmission electron microscopy (TEM) was used for detecting constituents in the TLP area. Unlike bonding below Tcr, TLP bonding at temperatures higher than Tcr resulted in formation of individual g‐g’ colonies in the adjacent base alloy to TLP bonding zone. Furthermore, isothermal solidification kinetic was reduced in these samples significantly. Microhardness and three‐point bending tests were carried out for determining the relationship between mechanical properties and developed microstructure in the TLP bonding area.
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Key words: TLP bonding, g‐g’ cell, bending test, IN‐738LC, BNi‐3, Microstructure [1]‐ O.A. Ojo, N.L. Richards and M.C. Chaturvedi, Scripta Materialia, 51, 683, (2004). [2]‐ O. A. Ojo, N. L. Richards and M. C. Chaturvedi, Scripta Materialia, 50, 641, (2004). ……………… DSL462 Mr. Faraj Tati Khanuordi Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran
Effect of Predeformation and Heat Treatment on Microstructure and Mechanical Properties of AL 6061 F.tati‐khanuordi, M.aghaei‐khafri Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran. In this research effect of predeformation and heat treatment on microstructure and mechanical properties of AL 6061 was investigated. The samples were rolled in different percent of deformation.After predeformation process the majority of structure was spherodies, anyway by increasing the predeformation rate the shape factor reduced in this process. According to observation the best process was tempering at 620 ˚C for 10 min for specimen with 35% deformation. It was proved each increasing on temperature and time caused grains coarsing and grain growth, therefore the yield point and mechanical properties got worse. Optical and Scanning Electron Microscopic methods, tensile and hardness tests have been used to evaluate the microstructure and mechanical properties. It seems, increasing in amount of predeformation, cause for improved mechanical properties and microstructure. The grain size was achieved by more deformation. [1]Lee Sang‐Yong, Lee Jung‐Hwan, Lee Young‐Seon, Journal of material processing Technology 111(2001) 42‐47 [2]Nursen Saklakoglu , I. Etem Saklakoglu , Metin Tanoglu ,Ozgu Oztas , Onder Cubukcuoglu , Journal of Materials Processing Technology 148 (2004) 103–107 ……………… DSL463 Mr. Mojib Amirkamali Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran
Precipitate Type Effect on Microstructure and Mechanical Properties of 17‐4 PH Stainless Steel during Different Heat Treatment Processes M.Amirkamali, M.aghaei‐khafri, D.Azimi‐yancheshmeh Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran. The microstructure and mechanical properties of 17‐4 PH stainless steel after solution heat treatment and aging processes was studied. Samples were divided to six batches that used for aging. After solution heat treatment, the structure included lath martensite. Precipitate particles were appeared after aging processes. The group of specimens was aged at 400˚C for 35 hour, has showed the best distribution of precipitates. Also this group of samples has showed optimum quantity of tensile and fatigue strength. It observed this aging process has resulted
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mitigation on mechanical properties rather than standard methods. During the process, the size of precipitate particles and their coherency were improved. Optical and Scanning Electron Microscopic, tensile, fatigue and hardness tests have been used to evaluate the microstructure and mechanical properties. It seems, by the modification between time and temperature, along with better tensile and fatigue strength, improved toughness and microstructure will be achieved. [1] Jun Wang, Hong Zou, Cong Li, Yanhua Peng, Shaoyu Qiu, Baoluo Shen, Nuclear Engineering and Design, Volume 236, Issue 24, December 2006, Pages 2531‐2536 [2] Jun Wang, Hong Zou, Cong Li, Shao‐yu Qiu, Bao‐luo Shen, Materials Characterization, Volume 57, Issues 4‐5, December 2006, Pages 274‐280 ……………… DSL465 Mr. Danial Azimi Yancheshmeh Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran
Effects of semisolid and ECAP processes on microstructure and mechanical properties of AA7075 D.Azimi‐Yancheshmeh, M. aghaei‐khafri, M.Amirkamali Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran. In this study, effect of equal channel angular pressing (ECAP) and semisolid processes on AA7075 (aluminum) was investigated. All specimens tolerated different passes for ECAP and different temperature for semisolid process. The best condition was 6 ECAP passes at 630˚C for 15 min. After semisolid and ECAP processes, structure with fine spherical grains (around 2µ) was appeared. It was observed, having both ECAP and semisolid processes can improve mechanical properties and microstructure better than condition that has only one of them. However the microstructure by using this process was better than received sample. Optical and Scanning Electron Microscopic methods, tensile and hardness tests have been used to evaluate the microstructure and mechanical properties. The H13 (1.2344) steel was used as an ECAP mold material for deformation. The mold for ECAP propose had two equal channels (1cm×1cm) with 90 degree between them. It seems, we can achieve Nono‐structure and better mechanical properties by increasing the number of passes and decreasing the ECAP angle. [1] Bing Q. Hana, Terence G. Langdon, Materials Science and Engineering A 410–411 (2005) 435–438 [2] S. Hossein Nedjad , H. Meidani , M. Nili Ahmadabadi, Materials Science and Engineering A 475 (2008) 224–228 SS6 ‐ LUCIA‐Microstructural control through diffusion processes)
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SPECIAL SESSION ON: Frontiers of Nanostructured Materials ORAGANISED BY: Prof. Dr. A. Shokuhfar K.N.Toosi University of Technology IRAN
[email protected] Prof. Dr. H.R. Rezaei Iran University of Science and Technology, IRAN
[email protected] DSL050 Prof. Kijung Yong Department of Chemical Engineering, Pohang University of Science and Technology, Korea
Low Temperature Solution Synthesis of ZnO Nanowires Array and Heteronanostructures Kijung Yong, Youngjo Tak
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Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790‐784, Korea, E‐mail:
[email protected] The assembly of 1D nanostructure in the fabrication of nanoelectronic, nanophotonic and energy devices is currently attracting significant attraction. In particular heteronanostructures are useful for the realization of multifunctional nanodevices because they are composed of different materials. In this paper we present a facile solution based synthetic route for the fabrication of ZnO nanowire arrays and various heterostructures of ZnO nanowires such as CdS/ZnO, Co3O4/ZnO and SiC/ZnO nanowires. Simple twostep solution methods were applied to synthesize these ZnO nanowire heterostructures. Synthesized heteronanostructures were characterized using SEM, TEM, XRD and XPS. Basic growth mechanism was investigated for heteronanostructures. Also, the applications of these novel heteronanostructures were studied. Photocatalytic properties of the heteronanostructures were studied using UV/visible light decomposition of organic dyes and the results were compared with bare ZnO nanowire sample. Heteronanostructures have showed much enhanced photocatalytic efficiencies and the mechanism will be discussed. Also, solar energy conversion devices were fabricated using ZnO nanowire heterostructures as photoanodes and discussion regarding this nanodevice will be presented. ……………… DSL317 Dr. Isabel Cristina Atias Adrian Dipartimento di Scienza dei Materiali ed Ingegneria Chimica, Politecnico di Torino, Turin, Italy
Hydrogen Absorption/Desorption in Nanostructured Doped Mg2Ni Alloys I.C. Atias‐Adrian1, F.A. Deorsola1, G.A. Ortigoza2, B. DeBenedetti1, M. Baricco3 1Dipartimento di Scienza dei Materiali ed Ingegneria Chimica, Politecnico di Torino, Turin, Italy 2Dipartimento di Energetica, Politecnico di Torino, Turin, Italy 3Dipartimento di Chimica IFM and NIS, Università di Torino, Turin, Italy Mg2Ni, Fe‐doped Mg2Ni and Ti‐doped Mg2Ni alloys for hydrogen storage applications have been produced by means of Mechanically Activated Self‐propagating High temperature Synthesis (MASHS). Different process parameters, such as the milling time for mechanical activation, the precursors stoichiometry and the SHS reaction time have been investigated. MASHS technique and the optimisation of its process parameters have been demonstrated to be effective for the obtainment of nanostructured pure and doped Mg2Ni intermetallics. Different Mg‐Ni based alloys have been tested in order to study their hydrogen sorption behavior. The hydrogenation was carried out in a Pressflow Gas Controller (20 bar, 300°C). Subsequently the dehydrogenation process was conducted following the kinetic by means of a Differential Scanning Calorimetry (DSC) equipped with an H2 detector of the purged gas. The effect of the heating rate (in the range from 3°C/min to 30 °C/min) on hydrogen desorption was determined. The morphology of the samples after the hydrogen absorption and desorption processes was studied by means of Field Emission Scanning Electronic Microscopy (FESEM), while X‐ray diffraction (XRD) was used to evaluate the phase composition, the crystal structure and the coherent domain size. The materials produced showed hydrogen storage capacities superior to 4wt%, especially in the case of Fe‐doped Mg2Ni and a light reduction of the desorption temperature was reached with Ti‐doped Mg2Ni. Finally the activation energy of the hydrogenation process was evaluated. An obtained result appears significant for possible technological applications of Mg‐based alloys. ……………… DSL452 Mr. Seunghyup Lee
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Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790‐784, Korea
Atomic Layer Deposition of Hafnium Silicate Nano‐Films Using Various Precursors S. Lee, J. Kim and K. Yong Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790‐784, Korea. Atomic layer chemical vapor deposition (ALCVD) of hafnium silicate films (HfxSi1‐xO2) using various kinds of alkoxide and amido precursors were compared. For the comparisons, hafnium silicate films were grown by ALCVD using hafnium‐(tetra‐tert‐butoxide) [Hf (OC(CH3)3)4 – HTB] and silicon amido precursors: tetrakis‐(diethylamino)‐ silane [Si(N(C2H5)2)4 – TDEAS] and tetrakis‐(dimethylamino)‐silane [Si(N(CH3)2)4 – TDMAS]. With using HTB and silicon amido precursors, the growth rates of hafnium silicate films were generally higher compared to the film growth using silicon alkoxide and hafnium amido precursors. In case of atomic concentration of the films, when HTB and silicon amido precursors were used, the films were hafnium‐rich compositions. The thermal stability of HTB was investigated at the same deposition condition and system. We could observe that HTB was thermally decomposed at the deposition temperature above 250 oC. Moreover, even less than 250 oC deposition temperatures, HTB react with residual oxygen and water vapor inside the chamber and form a film. It seems apparent that the instability of HTB cause the high growth rate and hafnium‐rich composition of grown films. ……………… DSL141 Dr. Massimo Celino ENEA, FIM Department, CR Casaccia, Via Anguillarese 301, 00123 Rome, Italy
Metallographic and Numerical Studies on the Role of Catalyst Particles of MgH2‐Mg System M. Celino1, A. Montone1, F. Cleri2, A. Aurora1, D. Mirabile Gattia1, S. Giusepponi1, M. Vittori Antisari1 1 ENEA, FIM Department, CR Casaccia, Via Anguillarese 301, 00123 Rome, Italy. 2 IEMN‐CNRS, Université des Sciences et Technologies de Lille, Villeneuve d’Ascq Cedex, France. Magnesium is one of the most promising materials for hydrogen storage due to its high capacity and low cost. Unfortunately, practical applications are for the moment limited by the slow kinetics and the high operating temperature. Nanostructuring magnesium hydride MgH2, generally by ball milling, introduces plastic deformations and catalysts that highly enhances the H2 absorption and desorption. However a fundamental understanding of the role played by catalysts and interfaces in the MgH2 is still lacking. Microscopic characterization of MgH2‐Mg system with and without heavy metal catalysts is achieved by combining accurate SEM observations of samples after partial desorption process [1] and atomic level ab‐initio molecular dynamics simulations of MgH2‐Mg interfaces [2]. The experimental method is based on low voltage SEM observations of cross sectional powder samples, prepared by a new specific metallographic process. Identification of nucleation sites of the sorption reaction and their correlation with the presence of catalyst particles is achieved by suitable experimental conditions. Moreover ab‐initio molecular dynamics clarifies the interplay of interfaces and the deformations induced during desorption by the presence of catalysts that are able to lower binding energies and free hydrogen
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atoms toward interfaces. Both approaches confirm and characterize the nucleation step in the catalysts driven phase transformation. [1] M. Vittori Antisari, A. Montone, A. Aurora, M. R. Mancini, D. Mirabile Gattia, L. Pilloni, accepted on Intermetallics. [2] A. Aurora, M. Celino, F. Cleri, D. Mirabile Gattia, S. Giusepponi, A. Montone, M. Vittori Antisari, in Mobile Energy, edited by G. Amaratunga, A. Nathan, M. Nookala, M.C. Smart (Mater. Res. Soc. Symp. Proc. Volume 1127E, Warrendale, PA, 2009), paper number 1127‐T07‐07. ……………… DSL170 Prof. Fatiha Kail GRMT, Department of physics, University of Girona, Campus Montilivi,Edif. PII, E‐17071, Girona, Spain
Hydrogen Diffusion Studies in Nano‐Structured Silicon by Thermal Analysis F. Kail1, J. Farjas1, P. Roura1, and P. Roca i Cabarrocas2 1 GRMT, Department of physics, University of Girona, Campus Montilivi,Edif. PII, E‐17071, Girona, Spain 2 LPICM, UMR 7647CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex, France Hydrogenated amorphous (a‐Si:H) and nanostructured (ns‐Si:H) silicon materials are currently used in large‐area devices, such as solar cells and liquid crystal displays. A better understanding of hydrogen incorporation, diffusion and evolution in these materials will facilitate the development of Si:H related materials and devices with improved electronic properties and stability [1,2]. We have undertaken a research to identify and characterize the diffusion of molecular hydrogen in ns‐Si:H thin films. These materials contain Si nanocrystals embedded in an amorphous Si matrix. In addition to the well‐known Evolved Gas Analysis (EGA) technique, traditionally used for these kinds of studies, we have used a Differential Scanning Calorimetry (DSC). DSC is the best suited technique to measure the energy exchange when hydrogen evolves [4], while EGA is one of the most successful methods to monitor H‐desorption and H‐characterization in Si:H materials [3]. From the simultaneous measurement of the energy exchange and hydrogen desorption, we have obtained valuable information about the H evolution and the H transport mechanism in ns‐Si:H. Experimental evidence of molecular hydrogen diffusion is given. A simple diffusion model shows good agreement with the experimental data. References [1] P.G. LeComber, R.J. Loveland, W.E. Spear and R. A. Vaughan. In: J. Stuke and W. Brenig, Editors, Amorphous and Liquid Semiconductors, Taylor and Francis, London (1974), p. 245. [2] D. Kaplan, N. Sol y G. Velasco, Appl. Phys. Lett., 33, 440 (1978). [3]. W. Beyer, Sol. Energy Mater. Sol. Cells 78, 235 (2003) [4] P. Roura, J. Farjas, C. Rath, J. Serra‐Miralles, E. Bertran, P. Roca i Cabarrocas, Phys. Rev. B 73, 085203 (2006). ……………… DSL184 Prof. Mehrdad Vahdati Mechanical Engineering Faculty, K.N.Toosi Univ. Of Tech., Tehran, Iran
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Air Characteristics in Air Turbine Spindle of Ultra Precision Machines M. Vahdati1, E. Azimi1, A.Shokouhfar1 1 Mechanical Engineering Faculty, K.N.Toosi Univ. Of Tech., Tehran, Iran Air Spindles have been used in ultra precision machines for several years because of their advantages such as high speed rotation, low friction, and low vibration,[1]. Air spindles are widely used in these machines for production of precise work pieces. Although, spindles function on a very complicated theoretical basis, [2,3] their structure is very simple and consists of mainly a rotor and a stator. The rotor/stator could be made of different shapes. A cylindrical shape is the one commonly in use. The spindle designed in this work has a spherical configuration. It has been designed with this configuration because it could be moved without application of an electric motor and only by a wind turbine system, [4]. The spindle studied in this research uses compressed air for rotor suspension, and has an air turbine for rotating its shaft. A thin air film acts as bearing layer between rotor and stator. In design procedure operation parameters such as air inlet pressure for turbine, air inlet pressure for bearing, diameter of turbine nuzzles, diameter of bearing nuzzles, clearance between rotor and stator and etc, [5], have been considered. A prototype spindle has been manufactured using design criteria. The influence of above mentioned parameters have been recognized through experiments. [1] The Design of Pressurized Gas Bearings, G.L.Shires, TRIBOLOGY, November (1966) [2] Design Data and A Manufacturing Technique for Spherical Hydrostatic Bearings in Machine Tool Applications W. B. Rowe and K. J. Stout (15 March 1971) [3] Design Data for Externally Pressurized Spherical Gas Bearings, K.J. Stout and M. Tawfik, TRIBOLOGY International, June (1977) [4] K. J. STOUT and W. B. ROWE, ‘Externally externally pressurized bearings design for Manufacture Part I ‐ journal bearing selection’ TRIBOLOGY international, June (1974) [5] Design procedures for orifice compensated gas journal bearings based on experimental data E.G. Pink and K.J. Stout TRIBOLOGY international February (1978) ……………… DSL189 Dr. Annalisa Paolone Sapienza Università di Roma, Dip. Fisica, Piazzale A. Moro 2, I‐00185 Roma, Italy
The Structural Phase Transition of Ammonia Borane: Effects of its Dispersion in Nanoscaffolds A. Paolone1,2, O. Palumbo1,3, P. Rispoli1, R. Cantelli1, T. Autrey4, A. Karkamkar4 1 Sapienza Università di Roma, Dip. Fisica, Piazzale A. Moro 2, I‐00185 Roma, Italy 2 Laboratorio Regionale SuperMAT, CNR‐INFM, Salerno, Italy 3 CNISM – Dip. Fisica, Sapienza Università, Piazzale A. Moro 2, I‐00185 Roma, Italy 4 Pacific Northwest National Laboratory, 908 Battelle Blvd., Richland, WA 99352, USA Ammonia borane, NH3BH3, is currently attracting noticeable interest in the field of solid state hydrogen storage due to its high hydrogen content (19 wt%). In the present study the structural phase transition of NH3BH3 bulk powder around 220 K was investigated combining anelastic spectroscopy and DSC measurements. In the fully hydrogenated compound, DSC indicates that the transition involves a latent heat and, therefore, is of first order. Anelastic spectroscopy measurements conducted in quasi‐static conditions show a very narrow hysteresis between cooling and heating (~0.4 K) and allow the transformation kinetics to be recorded in detail.[1] Partial deuteration results in a slowing down of the transformation kinetics. Furthermore, the transition is slightly shifted to higher temperature in ND3BH3 and NH3BD3 (~0.7 K). In NH3BH3 a thermally activated relaxation peak is revealed around
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100 K for a sample vibration frequency of ~1 kHz and it is attributed to the dynamics of the rotations and torsions of the NH3‐BH3 groups. The deuterated samples present also additional processes, whose origin is under investigation. It was recently reported that the infusion of ammoniaborane into meso‐porous silica has beneficial effects on the desorption rates at low temperature, on the contamination of hydrogen from borazine and on the dehydrogenation enthalpy [2]. We investigated to which extent the basic physical properties of ammonia borane are preserved when this compound is dispersed in porous silica scaffolds. In particular we studied, for the first time, the structural phase transition in ammonia borane dispersed in a MCM‐41 nanoscaffold by means of DSC and anelastic spectroscopy. We found that NH3BH3 finely dispersed in the channels of mesoporous silica does not undergo the structural phase transition present in the bulk, thus proving that nanoconfining drastically affects the molecular interactions. [3] [1] A. Paolone et al., J. Phys. Chem. C doi 10.1021/jp810708g [2] A. Gutowska, et al., Angew. Chem., Int. Ed. 2005, 44, 3578‐3582 [3] A. Paolone et al., J. Phys. Chem. C, submitted ……………… DSL196 Mrs. Suriati Sufian Petronas University, Malaysia
Optimization for Development of Carbon Nanotubes Using Taguchi Method at Constant Temperature S. Sufian1, S. Yusup1, F.R. Ahmadun2 1 Universiti Teknologi PETRONAS, 31750 Tronoh, Perak, Malaysia. 2Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia. In this study, an optimization of floating catalyst chemical vapor deposition (FC‐CVD) using Taguchi method is done in developing multiwall carbon nanotubes (MWNTs) at constant temperature. The reaction is run at temperature of 850°C in atmospheric pressure with ferrocene as the catalyst precursor and benzene as the carbon feedstock. By applying Taguchi’s method as the design of experiment, three parameters that are reaction time, hydrogen flow rate and catalyst weight have been varied during the optimization of the experiment. The results show that the BET specific surface area increases as the reaction time increases, the degree of graphitization reduces as the mass of the catalyst increases and the relative value of amorphous carbon to graphite carbon decreases as the hydrogen flow rate increases. ……………… DSL228 Prof. L. Q. Wang Department of Mechanical Engineering, the University of Hong Kong,Pokfulam Road, Hong Kong
Frontiers in Nanofluids L. Q. Wang Department of Mechanical Engineering, the University of Hong Kong, Pokfulam Road, Hong Kong (
[email protected])
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Nanofluids are a new class of fluids engineered by dispersing nanometer‐size structures (particles, fibers, tubes, droplets) in base fluids. The very essence of nanofluids research and development is to enhance fluid macroscopic properties such as thermal conductivity through manipulating microscopic physics (structures, properties and activities). Therefore, the success of nanofluid technology depends very much on how well we can address questions like how to effectively manipulate at nanoscale, what is the macroscopic manifestation of microscopic physics, and how to optimize microscopic physics for optimal macroscopic properties. In this presentation we review methodologies available to effectively tackle these central but difficult problems and identify the future research needs as well. While our focus is on thermal nanofluids (the heat‐conduction fluids in particular), the methodologies are equally valid for the other types of nanofluids. ……………… DSL303 Prof. Jun Onoe Tokyo Institute of Technology, Japan
One‐dimensional peanut–shaped C60 polymer as a new quantum system
J. Onoe1*, T. Ito2, H. Shima3, Y. Toda3, H. Yoshioka4, and S. Kimura2 1 Tokyo Institute of Technology, Meguro, Tokyo 152‐8550, JPN. 2 Institute for Molecular Science, Okazaki, Aichi 444‐8585, JPN. 3 Hokkaido University, Sapporo, Hokkaido 060‐8628, JPN. 4 Nara Women’s University, Nara 630‐8506, JPN We found that electron‐beam (EB) induced polymerization of C60 results in formation of a peanut‐shaped C60 polymer with metallic electron‐transport properties in air at room temperature [1]. The temperature dependence of the photo‐excited carriers lifetime for the peanut‐shaped polymer indicated the energy gap formation at below 50 K in a similar manner to the Peierls transition of quasi one‐dimensional (1D) metallic materials such as K0.3MO3 [2]. More recently, we examined the valence photoelectron spectra of the polymer, using in situ high‐resolution ultraviolet photoelectron spectroscopy, and have observed the Tomonaga‐Luttinger liquids (TLL) behavior as well as for metallic single‐walled carbon nanotubes [3]. These facts evidence that the peanut‐shaped C60 polymer is a 1D metal. In addition, as shown in FIG 1, the 1D peanut‐shaped C60 polymer has both positive and negative Gaussian curvatures ( ) lined alternatively and periodically. To our best knowledge, this polymer can be classified as a new ‐electron conjugated carbon allotrope unlike graphite (k = 0), fullerenes (k > 0), nanotubes (k = 0 at body, k > 0 at cap edge), and hypothetical Mackay crystal (k