DOCSLIB.ORG

Universite De Limoges

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Universite De Limoges UNIVERSITE DE LIMOGES ECOLE DOCTORALE Science et Ingénierie en Matériaux, Mécanique, Energétique et Aéronautique (SI-MMEA) Laboratoire Science des Procédés Céramiques et de Traitements de Surface (SPCTS) Thèse pour obtenir le grade de DOCTEUR DE L’UNIVERSITÉ DE LIMOGES Discipline / Spécialité : Matériaux céramique et traitements de surface présentée et soutenue par Mathias GEORGES Thèse de doctorat Thèse de le 15 décembre 2016 Approche du frittage SPS de céramiques fines de carbure de bore : rôle des poudres initiales et de la mise en forme Thèse dirigée par Alexandre Maître, co-dirigée par Guy Antou, et co-encadrée par Nicolas Pradeilles JURY : Présidente M. Nathalie Moncoffre, Directeur de recherche CNRS, Université de Lyon, IPNL Rapporteurs M. Frédéric Bernard, Professeur, Université de Bourgogne, ICB M. Sébastien Mercier, Professeur, Université de Lorraine, LEM3 Examinateurs M. François Barthelemy, Ingénieur, DGA Bourge M. Grégory Etchegoyen, Docteur, Directeur du CTTC M. Nicolas Pradeilles, Maitre de Conférences, Université de Limoges, SPCTS (co-encadrant) M. Guy Antou, Maître de Conférences-HDR, Université de Limoges, SPCTS (co-directeur de thèse) M. Alexandre Maître, Professeur, Université de Limoges, SPCTS (directeur de thèse) GEORGES Mathias | Université de Limoges | 2017 A maman, partie trop tôt pour voir le fruit de son travail GEORGES Mathias | Université de Limoges | 2017 GEORGES Mathias | Université de Limoges | 2017 Remerciements J’aimerais tout d’abord remercier mon directeur de thèse, Alexandre Maître, pour sa confiance et ses précieux conseil. Mes remerciements s’adressent aussi à mes deux encadrants Guy Antou et Nicolas Pradeilles pour leurs disponibilités, leurs critiques qui m’ont permis de mener cette thèse à bien. Je tiens à remercier aussi Monsieur François Barthelemy, Ingénieur à la DGA, pour son implication dans ces travaux. Qu’il trouve ici l’expression de toute ma reconnaissance pour ses encouragements. J’exprime ma profonde reconnaissance à Monsieur Frédéric Bernard, Professeur à l’Université de Bourgogne, et à Monsieur Sébastien Mercier, Professeur à l’Université de Lorraine, pour l’honneur qu’ils m’ont fait d’avoir accepté d’être rapporteur de cette thèse. Je remercie également Madame Nathalie Moncoffre, Directeur de recherche CNRS à l’Université de Lyon, et Monsieur Grégory Etchegoyen, Docteur et Directeur du CTTC, pour leurs investissements dans cette étude et pour avoir participé au jury de soutenance. Mes remerciements vont aussi aux membres de mon bureaux, Daniel Ohin, et Loïck Bonnet pour m’avoir supporté et encouragé pendant ses trois ans et plus particulièrement pendant cette phase de rédaction. Enfin, un merci tout particulier à ma compagne et à ma famille pour leur soutien constant durant toutes ces années. GEORGES Mathias | Université de Limoges | 2017 Sommaire Introduction ................................................................................................................................ 1 1 Synthèse bibliographique ................................................................................................... 5 1.1 Le carbure de bore ....................................................................................................... 7 1.1.1 Diagramme de phases ........................................................................................... 7 1.1.2 Structure cristalline idéale du carbure de bore ..................................................... 7 1.1.3 Position des atomes de bore et de carbone en fonction de la stœchiométrie ..... 10 1.2 Synthèse du carbure de bore ...................................................................................... 14 1.2.1 Synthèse par carboréduction .............................................................................. 14 1.2.2 Synthèse par magnésiothermie ........................................................................... 16 1.3 Le frittage naturel et HP du carbure de bore ............................................................. 17 1.3.1 Définition et généralités sur le frittage ............................................................... 17 1.3.2 Mécanismes de transport de la matière .............................................................. 19 1.3.3 Le frittage de B4C par frittage naturel et Hot Pressing (HP) .............................. 20 1.4 Le frittage de B4C par Spark Plasma Sintering (SPS) ............................................... 22 1.4.1 Le procédé SPS .................................................................................................. 22 1.4.2 Effets spécifiques présumés en frittage SPS ...................................................... 23 1.4.3 Le frittage du carbure de bore par SPS .............................................................. 25 1.5 Simulation numérique multi-physique du procédé SPS ............................................ 30 1.5.1 Couplage électro-thermique ............................................................................... 31 1.5.2 Couplage thermo-mécanique .............................................................................. 35 1.6 Conclusion ................................................................................................................. 37 2 Modélisation du procédé SPS - approches expérimentale et numérique ......................... 41 2.1 Instrumentation de la machine SPS ........................................................................... 42 2.1.1 Dispositif de frittage SPS utilisé et géométrie de l’outillage ............................. 42 2.1.2 Développement d’une instrumentation électrique et thermique spécifique ....... 43 2.1.3 Caractéristiques de fonctionnement de la source de courant pulsé .................... 46 2.2 Modélisation numérique électro-thermique ............................................................... 53 2.2.1 Propriétés des matériaux présents dans l’enceinte SPS ..................................... 53 2.2.2 Système d’équations différentielles ................................................................... 55 2.2.3 Conditions aux limites ........................................................................................ 56 2.2.4 Effet du courant pulsé sur la cinétique de chauffage ......................................... 59 GEORGES Mathias | Université de Limoges | 2017 2.3 Application du modèle au carbure de bore ................................................................ 63 2.4 Changement d’échelle et application du modèle électrothermique ........................... 67 2.5 Conclusion ................................................................................................................. 71 3 Frittage SPS du carbure de bore ....................................................................................... 73 3.1 Caractérisations des poudres de carbure de bore ....................................................... 73 3.1.1 Caractérisations structurales ............................................................................... 73 3.1.2 Caractérisations morphologiques ....................................................................... 75 3.1.3 Analyse chimique ............................................................................................... 78 3.1.4 Résumé des analyses des lots de poudres de carbure de bore ............................ 79 3.2 Frittage du carbure de bore par SPS .......................................................................... 80 3.2.1 Protocole expérimental ....................................................................................... 80 3.2.2 Evolution de la densité ....................................................................................... 81 3.2.3 Evolution de la composition au cours du frittage ............................................... 84 3.3 Evolution de la taille des grains en fonction de la densité ......................................... 90 3.4 Identification des mécanismes de densification ........................................................ 93 3.4.1 Modèle de comportement d’Olevsky ................................................................. 93 3.4.2 Méthode de détermination des paramètres de densification .............................. 94 3.4.3 Résultats et discussion ........................................................................................ 96 3.5 Conclusion ............................................................................................................... 102 4 Rôle de la mise en forme sur le frittage SPS du carbure de bore ................................... 105 3.1. Formulation des suspensions : sélection des solvants ............................................. 105 3.1.1. Bibliographie sur la mise en suspension d’une poudre de carbure de bore ..... 106 3.1.2. Bibliographie sur la mise en suspension du carbure de silicium ...................... 109 3.1.3. Solvants sélectionnés ........................................................................................ 110 3.2. Résultats des essais de préparation de suspensions à partir de la poudre commerciale HC Starck de carbure de bore ............................................................................................ 113 3.2.1. Evaluation de la stabilité temporelle ................................................................ 113 3.2.2. Evaluation de la stabilité temporelle par granulométrie laser .......................... 115 3.2.3. Analyse morphologique ..................................................................................
Load more

Recommended publications
  • Enhancing the Hardness of Superhard Transition-Metal Borides: Molybdenum-Doped Tungsten Tetraboride † ‡ ‡ ‡ ‡ Reza Mohammadi,*, Christopher L
    Article pubs.acs.org/cm Enhancing the Hardness of Superhard Transition-Metal Borides: Molybdenum-Doped Tungsten Tetraboride † ‡ ‡ ‡ ‡ Reza Mohammadi,*, Christopher L. Turner, Miao Xie, Michael T. Yeung, Andrew T. Lech, ‡ § ∥ ‡ § ∥ Sarah H. Tolbert, , , and Richard B. Kaner*, , , † Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia 23284, United States ‡ § ∥ Department of Chemistry and Biochemistry, Department of Materials Science and Engineering, and California NanoSystems Institute (CNSI), University of California, Los Angeles (UCLA), Los Angeles, California 90095, United States ABSTRACT: By creation of solid solutions of the recently explored low- cost superhard boride, tungsten tetraboride (WB4), the hardness can be increased. To illustrate this concept, various concentrations of molybdenum − (Mo) in WB4, that is, W1−xMoxB4 (x = 0.00 0.50), were systematically synthesized by arc melting from the pure elements. The as-synthesized samples were characterized using energy-dispersive X-ray spectroscopy (EDS) for elemental analysis, powder X-ray diffraction (XRD) for phase identification, Vickers microindentation for hardness testing, and thermal gravimetric analysis for determining the thermal stability limit. While the EDS analysis confirmed the elemental purity of the samples, the XRD results indicated that Mo is completely soluble in WB4 over the entire concentration range studied (0−50 at. %) without forming a second phase. When 3 at. % Mo is added to WB4, Vickers hardness values increased by about 15% from 28.1 ± 1.4 to 33.4 ± 0.9 GPa under an applied load of 4.90 N and from 43.3 ± 2.9 to 50.3 ± 3.2 GPa under an applied load of 0.49 N.
    [Show full text]
  • Wo 2010/141206 A2
    (12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (19) World Intellectual Property Organization International Bureau (10) International Publication Number (43) International Publication Date 9 December 2010 (09.12.2010) WO 2010/141206 A2 (51) International Patent Classification: (81) Designated States (unless otherwise indicated, for every B24D 11/00 (2006.01) B24B 27/06 (2006.01) kind of national protection available): AE, AG, AL, AM, B23D 61/18 (2006.01) B24D 3/00 (2006.01) AO, AT, AU, AZ, BA, BB, BG, BH, BR, BW, BY, BZ, CA, CH, CL, CN, CO, CR, CU, CZ, DE, DK, DM, DO, (21) International Application Number: DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT, PCT/US2010/035227 HN, HR, HU, ID, IL, IN, IS, JP, KE, KG, KM, KN, KP, (22) International Filing Date: KR, KZ, LA, LC, LK, LR, LS, LT, LU, LY, MA, MD, 18 May 2010 (18.05.2010) ME, MG, MK, MN, MW, MX, MY, MZ, NA, NG, NI, NO, NZ, OM, PE, PG, PH, PL, PT, RO, RS, RU, SC, SD, (25) Filing Language: English SE, SG, SK, SL, SM, ST, SV, SY, TH, TJ, TM, TN, TR, (26) Publication Language: English TT, TZ, UA, UG, US, UZ, VC, VN, ZA, ZM, ZW. (84) Designated States (unless otherwise indicated, for every (30) Priority Data: 61/184,479 5 June 2009 (05.06.2009) US kind of regional protection available): ARIPO (BW, GH, GM, KE, LR, LS, MW, MZ, NA, SD, SL, SZ, TZ, UG, (71) Applicant (for all designated States except US): AP¬ ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, MD, RU, TJ, PLIED MATERIALS, INC.
    [Show full text]
  • Glossary of Terms
    Glossary of Terms Acceptable Daily Intake or Allowed Daily Intake (ADI) → Dose- Response Relationship/Curve Allergen The allergen is a material which triggers an allergic reaction. Allopathy The term allopathy was created by Christian Friedrich Samuel Hahnemann (1755– 1843) (from the Greek prefix άλλος, állos, “other”, “different” and the suffix πάϑος, páthos, “suffering”) in order to distinguish his technique (homeopathy) from the traditional medicine of his age. Today, allopathy means a medicine based on the principles of modern pharmacology. Anaphylactic shock Anaphylaxis (or an anaphylactic shock) is a whole-body, rapidly developing aller- gic reaction, which may lead to lethal respiratory and circulatory failure. Antibody Antibodies are proteins produced by the immune system to neutralize exogenous (external) substances. Chromatography, chromatogram Chromatography is the common name of different techniques used to separate mix- tures of compounds. HPLC stands for high-performance liquid chromatography. A chromatogram is the pattern of separated substances obtained by chromatography. Colloidal sol A colloidal sol is a suspension of very small solid particles in a continuous liquid medium. Colloidal sols are quite stable and show the Tyndall effect (light scatter- ing by particles in a colloid). They can be quite stable. Examples include blood, pigmented ink, and paint. Colloidal sols can change their viscosity quickly if they © Springer International Publishing Switzerland 2014 311 L. Kovács et al., 100 Chemical Myths, DOI 10.1007/978-3-319-08419-0 312 Glossary of Terms are thixotropic. Examples include quicksand and paint, both of which become more fluid under pressure. Concentrations: parts per notations In British/American practice, the parts-per notation is a set of pseudo-units to de- scribe concentrations smaller than thousandths: 1 ppm (parts per million, 10−6 parts) One out of 1 million, e.g.
    [Show full text]
  • UCLA Electronic Theses and Dissertations
    UCLA UCLA Electronic Theses and Dissertations Title Synthesis, Structure, and Properties of Refractory Hard-Metal Borides Permalink https://escholarship.org/uc/item/1hv5m731 Author Lech, Andrew Thomas Publication Date 2014 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California UNIVERSITY OF CALIFORNIA Los Angeles Synthesis, Structure, and Properties of Refractory Hard-Metal Borides A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Chemistry by Andrew Thomas Lech 2014 ©Copyright by Andrew Thomas Lech 2014 ABSTRACT OF THE DISSERTATION Synthesis, Structure, and Properties of Refractory Hard-Metal Borides by Andrew Thomas Lech Doctor of Philosophy in Chemistry University of California, Los Angeles, 2014 Professor Richard B. Kaner, Chair As the limits of what can be achieved with conventional hard compounds, such as tungsten carbide, are nearing reach, super-hard materials are an area of increasing industrial interest. The refractory hard metal borides, such as ReB 2 and WB 4, offer an increasingly attractive alternative to diamond and cubic boron nitride as a next-generation tool material. In this Thesis, a thorough discussion is made of the progress achieved by our laboratory towards understanding the synthesis, structure, and properties of these extremely hard compounds. Particular emphasis is placed on structural manipulation, solid solution formation, and the unique crystallographic manifestations of what might also be called “super- hard metals”. ii The dissertation of Andrew Thomas Lech is approved. ____________________________________________ Sarah Tolbert ____________________________________________ Vijay Gupta ____________________________________________ Richard B. Kaner, Committee Chair University of California, Los Angeles 2014 iii TABLE OF CONTENTS ABSTRACT OF THE DISSERTATION .........................................................................................................................
    [Show full text]
  • De Ning the True Hardness of Materials Harder Than Single Crystal Diamond
    Dening the true hardness of materials harder than single crystal diamond Guodong (David) Zhan ( [email protected] ) Saudi Aramco (Saudi Arabia) Jin Liu Sichuan University Pei Wang High Pressure Science and Engineering Center, University of Nevada Liping Wang Southern University of Science and Technology https://orcid.org/0000-0002-6137-3113 Xiaozhi Yan High Pressure Science and Engineering Center, University of Nevada Yongtao Zou Shenzhen Technology University Duanwei He Sichuan University Chinthaka Gooneratne Saudi Aramco (Saudi Arabia) Jianhui Xu Saudi Aramco Alawi Alalsayednassir Saudi Aramco (Saudi Arabia) Timothy Moellendick Saudi Aramco (Saudi Arabia) Article Keywords: diamond, superhard materials, Vickers Hardness Tester Posted Date: June 25th, 2021 DOI: https://doi.org/10.21203/rs.3.rs-614606/v1 License: This work is licensed under a Creative Commons Attribution 4.0 International License. Read Full License Defining the true hardness of materials harder than single crystal diamond Jin Liu1,2,3, Guodong (David) Zhan4*, Pei Wang3, Liping Wang3*, Xiaozhi Yan3, Yongtao Zou5, Duanwei He1*, Chinthaka P. Gooneratne4, Jianhui Xu4, Alawi G Alalsayednassir,6 Timothy Eric Moellendick4 Affiliations: 1Institute of Atomic and Molecular Physics, Sichuan University; Chengdu 610065, People’s Republic of China. 2School of Mechanical Engineering, Jingchu University of Technology; Jingmen 44800, People’s Republic of China. 3Academy for Advanced Interdisciplinary Studies, and Department of Physics, Southern University of Science and Technology; Shenzhen 518055, People’s Republic of China. 4Drilling Technology Division, Exploration and Petroleum Engineering – Advanced Research Center; Saudi Aramco, Dhahran 31311, Saudi Arabia. 5College of Engineering Physics, and Center for Advanced Material Diagnostic Technology, Shenzhen Technology University; Shenzhen 518118, People’s Republic of China.
    [Show full text]
  • Scientific American-July 2007
    Must Science and Religion Be Enemies? (see page 88) Warmer Water, SUPER HURRICANES page 44 July 2007 www.SciAm.com The MEMORY CODE Learning to read minds by understanding how brains store experiences Hijacked Cells How Tumors Exploit the Body’s Defenses Wireless Light Beats Radio for Broadband No-Man’s- Land Suppose Humans Just Vanished ... COPYRIGHT 2007 SCIENTIFIC AMERICAN, INC. FEATURES ■ SCIENTIFIC AMERICAN July 2007 ■ Volume 297 Number 1 ENVIRONMENT 76 An Earth without People Interview with Alan Weisman 76 One way to examine humanity’s impact on the environment is to consider how the world would fare if all the people disappeared. CLIMATE CHANGE 44 Warmer Oceans, 44 Stronger Hurricanes 52 By Kevin E. Trenberth Evidence is mounting that global warming enhances a cyclone’s damaging winds and fl ooding rains. COVER STORY: BRAIN SCIENCE 52 The Memory Code 60 By Joe Z. Tsien Researchers are closing in on the rules that the brain uses to lay down memories. Discovery of this memory code could lead to new ways to peer into the mind. 60 68 MEDICINE 60 A Malignant Flame By Gary Stix Understanding chronic infl ammation, which contrib- utes to heart disease, Alzheimer’s and other ailments, may be a key to unlocking the mysteries of cancer. GENETICS 68 The Evolution of Cats ON THE COVER By Stephen J. O’Brien and Warren E. Johnson Artist Jean-Francois Podevin (www.podevin.com) Genomic paw prints in the DNA of the world’s wild fancifully depicts the goal of uncovering a universal cats have clarifi ed the feline family tree and uncovered neural code: the rules the brain uses to identify and several remarkable migrations in their past.
    [Show full text]
  • WATER CHEMISTRY CONTINUING EDUCATION PROFESSIONAL DEVELOPMENT COURSE 1St Edition
    WATER CHEMISTRY CONTINUING EDUCATION PROFESSIONAL DEVELOPMENT COURSE 1st Edition 2 Water Chemistry 1st Edition 2015 © TLC Printing and Saving Instructions The best thing to do is to download this pdf document to your computer desktop and open it with Adobe Acrobat DC reader. Adobe Acrobat DC reader is a free computer software program and you can find it at Adobe Acrobat’s website. You can complete the course by viewing the course materials on your computer or you can print it out. Once you’ve paid for the course, we’ll give you permission to print this document. Printing Instructions: If you are going to print this document, this document is designed to be printed double-sided or duplexed but can be single-sided. This course booklet does not have the assignment. Please visit our website and download the assignment also. You can obtain a printed version from TLC for an additional $69.95 plus shipping charges. All downloads are electronically tracked and monitored for security purposes. 3 Water Chemistry 1st Edition 2015 © TLC We require the final exam to be proctored. Do not solely depend on TLC’s Approval list for it may be outdated. A second certificate of completion for a second State Agency $25 processing fee. Most of our students prefer to do the assignment in Word and e-mail or fax the assignment back to us. We also teach this course in a conventional hands-on class. Call us and schedule a class today. Responsibility This course contains EPA’s federal rule requirements. Please be aware that each state implements drinking water/wastewater/safety regulations may be more stringent than EPA’s or OSHA’s regulations.
    [Show full text]
  • Electronic, Dynamical, and Thermal Properties of Ultra-Incompressible Superhard Rhenium Diboride: a Combined first-Principles and Neutron Scattering Study
    PHYSICAL REVIEW B 76, 184113 ͑2007͒ Electronic, dynamical, and thermal properties of ultra-incompressible superhard rhenium diboride: A combined first-principles and neutron scattering study W. Zhou,1,2,* H. Wu,1,3 and T. Yildirim1,2 1NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA 2Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA 3Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA ͑Received 27 August 2007; published 19 November 2007͒ Rhenium diboride is a recently recognized ultra-incompressible superhard material. Here we report the ͑ ͒ ͑ ͒ electronic e , phonon p , e-p coupling, and thermal properties of ReB2 from first-principles density- ͑ functional theory calculations and neutron scattering measurements. Our calculated elastic constants c11 ͒ ͑ Ϸ ͒ =641 GPa, c12=159 GPa, c13=128 GPa, c33=1037 GPa, and c44=271 GPa , bulk modulus B 350 GPa and hardness ͑HϷ46 GPa͒ are in good agreement with the reported experimental data. The calculated phonon density of states agrees very well with our neutron vibrational spectroscopy result. Electronic and phonon analysis indicates that the strong covalent B-B and Re-B bonding is the main reason for the super incompress- ibility and hardness of ReB2. The thermal expansion coefficients, calculated within the quasiharmonic approxi- mation and measured by neutron powder diffraction, are found to be nearly isotropic in a and c directions and only slightly larger than that of diamond in terms of magnitude. The excellent agreement found between calculations and experimental measurements indicate that first-principles calculations capture the main inter- actions in this class of superhard materials, and thus can be used to search, predict, and design new materials with desired properties.
    [Show full text]
  • New Zirconium Diboride Polymorphs—First-Principles Calculations
    materials Article New Zirconium Diboride Polymorphs—First-Principles Calculations Marcin Ma´zdziarz* and Tomasz Mo´scicki Institute of Fundamental Technological Research Polish Academy of Sciences, 02-106 Warsaw, Poland; [email protected] * Correspondence: [email protected]; Tel.: +48-22-826-12-81 Received: 3 June 2020; Accepted: 3 July 2020; Published: 6 July 2020 Abstract: Two new hypothetical zirconium diboride (ZrB2) polymorphs: (hP6-P63/mmc-space group, no. 194) and (oP6-Pmmn-space group, no. 59), were thoroughly studied under the first-principles density functional theory calculations from the structural, mechanical and thermodynamic properties point of view. The proposed phases are thermodynamically stable (negative formation enthalpy). Studies of mechanical properties indicate that new polymorphs are less hard than the known phase (hP3-P6/mmm-space group, no. 191) and are not brittle. Analysis of phonon band structure and density of states (DOS) also show that the phonon modes have positive frequencies everywhere and the new ZrB2 phases are not only mechanically but also dynamically stable. The estimated acoustic Debye temperature, QD, for the two new proposed ZrB2 phases is about 760 K. The thermodynamic properties such as internal energy, free energy, entropy and constant-volume specific heat are also presented. Keywords: zirconium diboride; ab initio calculations; mechanical properties; elastic properties; phonons 1. Introduction During latest years, the transition metal borides have attracted attention among materials researchers due to the combination of their outstanding physical properties such as electric and thermal conductivity comparable with metals, low compressibility, high shear strength and exceptionally high hardness [1,2]. Even in the form of thin films, they possess extraordinary properties such as very high hardness with increased flexibility, great thermal properties and very good corrosion and wear resistance [3–5].
    [Show full text]
  • Physical Properties of Various Conductive Diborides and Their Binaries Austin Harold Shaw Iowa State University
    Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2015 Physical properties of various conductive diborides and their binaries Austin Harold Shaw Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Materials Science and Engineering Commons, and the Mechanics of Materials Commons Recommended Citation Shaw, Austin Harold, "Physical properties of various conductive diborides and their binaries" (2015). Graduate Theses and Dissertations. 14496. https://lib.dr.iastate.edu/etd/14496 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Physical properties of various conductive metal diborides and their binaries by Austin Harold Shaw A dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Major: Materials Science and Engineering Program of Study Committee: Alan Russell, Major Professor Iver Anderson Ashraf Bastawros Scott Beckman Terrence Meyer Iowa State University Ames, Iowa 2015 Copyright © Austin Harold Shaw, 2015. All rights reserved. ii TABLE OF CONTENTS ABSTRACT iii CHAPTER 1: INTRODUCTION 1 CHAPTER 2: EXPERIMENTAL PROCEDURE 17 CHAPTER 3: RESULTS AND DISCUSSION 22 CHAPTER 4: CONCLUSION 57 CHAPTER 5: FUTURE WORK 60 APPENDIX 1: XRD ANALYSES 61 APPENDIX 2: TERNARY PHASE DIAGRAMS 75 APPENDIX 3: LOOP ABRASION DATA 81 APPENDIX 4: COUNTER-FACE PROFILOMETRY DATA 109 REFERENCES 117 iii ABSTRACT Hard, wear-resistant materials have potential utility as both coatings and bulk components in wear-prone applications.
    [Show full text]
  • Coevolutionary Prediction of Materials with Optimal Target
    Skolkovo Institute of Science and Technology COEVOLUTIONARY SEARCH FOR MATERIALS WITH OPTIMAL PROPERTIES IN THE SPACE OF BINARY SYSTEMS Doctoral Thesis by ZAHED ALLAHYARI DOCTORAL PROGRAM IN MATERIALS SCIENCE AND ENGINEERING Supervisor Professor Artem R. Oganov Moscow – 2020 © Zahed Allahyari 2020 I hereby declare that the work presented in this thesis was carried out by myself at Skolkovo Institute of Science and Technology, Moscow, except where due acknowledgement is made, and has not been submitted for any other degree. Candidate (Zahed Allahyari) Supervisor (Prof. Artem R. Oganv) ii DEDICATION I dedicate this thesis to my dear wife whose support sustained me throughout my graduate studies. iii Abstract Fast developments in technology and industry require optimal materials for various applications, which highlights the role of materials science in solving its central problem: discovery of optimal materials, having any required properties, in the entire chemical space (i.e., among all possible combinations of elements across the periodic table). Despite the great development of computers and the success of the crystal structure prediction methods such as metadynamics1 and evolutionary algorithms,3–5 the problem has remained unsolved because of the high level of complexity. This thesis summarizes our efforts to solve it. We present the coevolutionary optimization algorithm, or Mendelevian search (MendS) method, that we developed to predict optimal materials while aiming for target properties, which was made possible by the implementation of well-designed variation operators. The multi-objective optimization technique, explained in Chapter 3, was used to ensure that the predicted materials are simultaneously optimal in a given property and have a minimal energy.
    [Show full text]
  • Exploring the Mechanical Anisotropy and Ideal Strengths of Tetragonal B4CO4
    materials Article Exploring the Mechanical Anisotropy and Ideal Strengths of Tetragonal B4CO4 Baobing Zheng *, Meiguang Zhang and Canjun Wang College of Physics and Optoelectronics Technology, Nonlinear Research Institute, Baoji University of Arts and Sciences, Baoji 721016, China; [email protected] (M.Z.); [email protected] (C.W.) * Correspondence: [email protected]; Tel.: +86-917-3364-258 Academic Editor: Giorgio Biasiol Received: 23 December 2016; Accepted: 26 January 2017; Published: 4 February 2017 Abstract: First-principles calculations were employed to study the mechanical properties for the recently proposed tetragonal B4CO4 (t-B4CO4). The calculated structural parameters and elastic constants of t-B4CO4 are in excellent agreement with the previous results, indicating the reliability of the present calculations. The directional dependences of the Young’s modulus and shear modulus for t-B4CO4 are deduced in detail, and the corresponding results suggest that the t-B4CO4 possesses a high degree of anisotropy. Based on the strain-stress method, the ideal tensile and shear strengths along the principal crystal directions are calculated, and the obtained results indicate that the shear mode along (001)[100] slip system dominates the plastic deformation of t-B4CO4, which can be ascribed to the breaking of the ionic B-O bonds. The weakest ideal shear strength of 27.5 GPa demonstrates that the t-B4CO4 compound is not a superhard material, but is indeed a hard material. Based on the atomic explanation that the ternary B-C-O compounds cannot acquire high ideal strength, we propose two possible routes to design superhard B-C-O compounds. Keywords: anisotropic properties; ideal strengths; superhard; B-C-O compound 1.
    [Show full text]