Download or read book Synthesis and Characterization of Transition Metal Diborides written by Jimmy Thörnberg and published by Linköping University Electronic Press. This book was released on 2021-01-20 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis is devoted towards physical vapor deposition (PVD) of thin films of transition-metal (TM) diborides, focused on the material system TiBx, Ti1-xAlxB2-y and CrBx. The metal diborides are a large family of compounds with both metallic and ceramic properties, due to its bonding nature being a mix of covalent and ionic bonds. Their characteristics include, e.g., good mechanical, electrical and thermal properties, while an improved oxidation and corrosion resistance are currently sought after. Furthermore, while the ideal composition of these diborides is TMB2, i.e. with a B to metal ratio of 2, the stoichiometry in the PVD deposited films typically diverges from this ratio. TiBx is often reported to be overstoichiometric, with x well above 2. One of the most known and commonly used member of the TM diboride family is TiBx, primarily used in hard-coating applications such as tools for machining Al. However, the material displays a fracture toughness and oxidation resistance that ideally needs to be improved. The films presented in this thesis were deposited by high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS). Using both methods facilitates an improved control of both microstructure and composition, and hence the materials properties. With HiPIMS, understoichiometric TiBx films were grown and it was shown that these films can match and even exceed the overstoichiometric counterpart, deposited with DCMS, in terms of mechanical properties. The hardness and fracture toughness for TiB1.43 films were measured at 43.9±0.9 GPa and 4.2±0.1 MPa√m, compared to TiB2.70 films at 37.7±0.8 GPa and 3.1±0.1 MPa√m. Furthermore, the understoichiometric films significantly improve the oxidation resistance. Air annealing of TiB1.43, TiB2.20, and TiB2.70 films at 400 °C showed an average oxidation rate of 2.9±1.5, 7.1±1.0, and 20.0±5.0 nm/h, respectively, explained by the microstructural difference between over- and understoichiometric material. In TiBx films where x > 2, there is a B-rich tissue phase in the grain boundaries which is suggested to enhance oxidation. The hydroscopic nature of B2O3 causes more rapid oxidation and evaporation thus providing an easy oxidation pathway in B-rich regions. However, understoichiometric films where x < 2 do not show any significant boundary phases. Instead, the B deficiency is presented as planar defects with Ti-rich stacking faults. Hence the absence of the B-rich tissue phase has strongly contributed to increasing the oxidation resistance. Oxidation resistance and mechanical properties were also investigated for understoichiometric Ti1-xAlxB2-y coatings with varying Ti:Al and B:M ratios, obtained from both HiPIMS and DCMS depositions. Al alloying of the TM diboride TiBx significantly enhances the oxidation resistance. However, incorporating too much Al is at the expense of the excellent hardness seen in the pure TiBx, going from 46.2±1.1 GPa to 22.6±1.1 GPa for Ti0.9Al0.1B1.3 and Ti0.3Al0.7B1.3, respectively. Hence, a reduction in the Al content is needed to retain the mechanical properties. The boundary phase in this material consists of a Ti1-xAlxB2-y tissue phase, rich in either Al or B depending on the x and y values. An improved oxidation resistance in Ti1-xAlxB2-y was seen with reduced Al and B content, proposed to be due to absence of tissue phase in the grain boundaries, in line with the observations for TiBx. The oxide scale thickness of Ti0.9Al0.1B1.3 and Ti0.9Al0.1B1.9 after air annealing at 600 °C for 10 h was measured to be 205 nm and 320 nm, respectively. Moreover, the trends indicate a reduced oxidation rate as the oxide scale grows thicker. A systematical study of DCMS deposited CrBx coatings, 1.90 ≤ x 2.08, was also performed, motivated by CrBx being a material of interest for providing potential corrosion resistance. All films, irrespectable of the deposition conditions, exhibited (001) texture, with epitaxial growth observed when increasing temperature from 500 °C to 900 °C. Higher density (5.2 g/cm3) and smoother surfaces was seen in films grown at lower pressure, 5 mTorr (0.67 Pa), compared to higher pressure, 20 mTorr (2.67 Pa), and was explained by less gas scattering leading to more energetic particles impinging on the surface. CrBx film composition show no apparent dependence on substrate temperature, and has a slight dependence on deposition pressure for the samples deposited at 900 °C, with reduced B content for increasing pressure. Overstoichiometric CrB2.08 films showed the presence of large B-rich inclusions, and B deficiency in CrB1.90 films presented as planar defects with Cr-rich stacking faults, similar to understoichiometric TiBx. The thorough investigations of all the systems in this thesis are aimed towards improving the understanding of the correlation between the thin film synthesis process and the resulting composition and microstructure, which in turn dictates the properties of thin films. A particular emphasis is put on control of composition. I den här avhandlingen fokuserar jag på beläggningar av tunna filmer, dvs. tunna lager av material som läggs på en yta för att ge ytan vissa specifika egenskaper. Jag genomför metodiska analyser av de filmer jag får från två olika beläggningsmetoder; ”high-power impulse magnetron sputtering” (HiPIMS) och den mer konventionella metoden ”directcurrent magnetron sputtering” (DCMS). Dessa metoder skiljer sig främst åt i antal parametrar man kan variera för att kontrollera processen som styr vilket material som bildas, där HiPIMS är den metod med flest parametrar. Anledningen till att HiPIMS inte har sett ett större användningsområde till dags dato är att det är en relativt ny process jämfört med DCMS, och på grund av den komplexitet som tillkommer när man utökar mängden tillväxtparametrar. För båda processerna är en grundläggande förståelse av både processen och materialet önskvärt för att få ett optimerat material, med specifika önskade egenskaper. Material i fokus i denna avhandling är TiBx, Ti1-xAlxB2-y och CrBx, även kallade övergångsmetall-diborider, där Ti står för titan, Al för aluminium, Cr för krom, B för bor, och x/y står för variabler i sammansättningen av materialet. Dessa diborider bär med sig unika egenskaper från respektive element och innehåller en blandning av kovalenta bindningar och jon-bindningar. Beroende på sammansättningen av atomer så kan vi se olika mekaniska, elektriska och termiska egenskaper samt olika grad av oxidering- och eroderings-resistans. TiBx är till exempel välkänt för sina tillämpningar inom skärande bearbetning, men har inte lika lovande egenskaper när det kommer till beständighet mot oxidering. Det här är delvis en konsekvens av att man idag kommersiellt använder sig främst av DCMS för tillväxt av dessa beläggningar, då denna metod typiskt genererar överstökiometriska tunna filmer av TiBx (x > 2), vilket i sin tur påverkar beständigheten mot oxidering negativt. Med hjälp av HiPIMS kan man kontrollera stökiometrin av filmen i större grad, och kan således generera understökiometrisk TiBx (x < 2) som jag visar på har bättre mekaniska egenskaper, bland annat högre hårdhet, bättre brottseghet och förbättrad beständighet mot oxidering, kontra den överstökiometriska motsvarigheten. Hur mikrostrukturen i överstökiometriska TiBx filmer ser ut är välkänt, där överflödigt B ansamlas i korngränserna och bilder en s.k. ”B-rik vävnadsfas”. Jag har påvisat hur motsvarande mikrostruktur ser ut för understökiometrisk TiBx filmer, något som fram tills nu varit okänt. I dessa faser saknas vävnadsfas i korngränserna, och istället hittas överskottet av Ti som plandefekter i de kolumnära TiB2-strukturerna i filmen. Jag visar på att avsaknaden av vävnadsfas i korngränserna tydligt förbättrar beständigheten mot oxidering, vilket troligtvis beror på att just korngränserna, och deras innehåll, agerar som en katalys for oxidering. På samma sätt undersöker jag hur materialsystemet Ti1-xAlxBy-2 beter sig med varierande Ti:Al förhållande och även B:M förhållande (bor till metall), i filmer skapade med både DCMS och HiPIMS. Målet med inkluderingen av Al är just att förbättra beständighet mot oxidering, och samtidigt bevara de åtråvärda mekaniska egenskaperna som filmer av TiBx har. Korngränserna i det här materialet består av en vävnadsfasblandning, rik på antingen Al eller B, beroende på förhållandet mellan x och y i Ti1- xAlxBy-2. Jag visar på att en reducering av denna vävnadsfas även här förbättrar beständigheten mot oxidering. Det påvisas genom att reducera Al- och B-innehållet i filmerna, vilket minskar vävnadsfasen i korngränserna, och således förbättras beständigheten mot oxidering. En systematisk undersökning av tunna filmer av CrBx, belagda med DCMS, har genomförts, då detta är ett materialsystem med potential för beständighet mot korrosion. Både lätt över- och understökiometriska filmer växtes, och fick sin mikrostruktur och lokala sammansättning undersökt. Alla filmer påvisade en (001) textur, med epitaxiell tillväxt när temperaturen ökade från 500 C° till 900 C°. Högre densitet (~5.2 g/cm3) och jämnare ytor sågs för filmer belagda vid lägre tryck, 5 mTorr (0.67 Pa), jämfört med högre tryck, 20 mTorr (2.67 Pa). Kompositionen för CrBx filmerna påvisade inte ett temperaturberoende, men visade ett marginellt beroende på beläggningstryck för prover växta vid 900 C°. Även observerat för understökiometriska CrB1.90 filmer är att underskottet av B presenteras som plandefekter med Cr-rika plan i de kolumnära CrB2- strukturerna i filmen, precis som i understökiometrisk TiBx. I överstökiometriska CrB2.08 filmer så visades stora inneslutningar av ansamlat B.

Download or read book Boron and Refractory Borides written by G.V. Samsonov and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 666 pages. Available in PDF, EPUB and Kindle. Book excerpt: V. I. MATKOVICH During the meeting of the International Symposium on Boron held in October, 1972 in Tbilisi, U.S.S.R., the idea was proposed to assemble a review of boron and refractory borides by the specialists present. The advantages of such a work were immediately apparent. Such diverse applications of borides as in protective armor, nuclear reactors, coat ings, reinforcement, etc. can hardly all be presented in sufficient detail by a single author. On the other hand it was also recognized that with so much specialization, some areas of interest may not be covered. Within the last decade or two a number of areas have been developed in which the use of refractory borides is growing and improvements are being actively explored. Thus, a number of borides have considerable potential as reinforcing material for plastics or light metals, though only boron fibers have been firmly established up to the present. Ap plication of flakes and films for two-dimensional reinforcement appears attractive, although the high cost of materials and development repre sents a considerable barrier. A number of borides have been used to manufacture lightweight protec tive armor. In this area relatively fast changes seem to be taking place as improvements in performance and weight are made. Boron carbide has found considerable use in this application and new developments exploit the light weight of beryllium borides.

Download or read book Groups IV V and VI Transition Metals and Compounds written by T. F. Connolly and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 219 pages. Available in PDF, EPUB and Kindle. Book excerpt: responsibility.) To Betty Edwards and Emily Copenhaver my thanks for what must have seemed endless typing, retyping and correcting of these bibliographies over a span of years. Availability of Documents U. S. Government contractor reports, usually identified by an alpha-numeric report number, can be purchased from National Technical Information Service U. S. Department of Commerce Springfield, Virginia 22151 and, often, on request from the issuing installation. USAEC reports are also available from International Atomic Energy Agency Kaerntnerring A 1010 Vienna, Austria National Lending Library Boston Spa England Monographs and reports of the National Bureau of Standards are for sale by Superintendent of Documents U. S. Government Printing Office Washington, D. C. 20402 Theses, listed as Dissertation Abstracts + number, are available in North or South America from University Microfilms Dissertation Copies P. O. Box 1764 Ann Arbor, Michigan 48106 and elsewhere from University Microfilms, Ltd. St. John's Road Tylers Green Penn, Buckinghamshire England Other Information Centers and New Journals New journals Information centers Field and and other sources serials Ultra purification 4, 8, 11, 13, 15, 16,19, 20, 9,11,15, 24, 31, 32 and 21, 28, 30, 32, 33, 42, 58, 59 crystal growth ix Preface Field Information centers New journals and and other -sources serials Characterization Miscellaneous 3,4, 8, 11, 13, 16, 19, 20, 1,3,4,8,11,15,17, 21, 26, 28, 30, 31, 32, 33, 35, 24, 25, 28, 29, 30, 31, 37, 38, 39, 40, 42, 46, 53, 56, 32 58, 60, 61, 62

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2008 with total page 868 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1975-02 with total page 850 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ultra High Temperature Ceramics written by William G. Fahrenholtz and published by John Wiley & Sons. This book was released on 2014-10-10 with total page 601 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first comprehensive book to focus on ultra-high temperature ceramic materials in more than 20 years Ultra-High Temperature Ceramics are a family of compounds that display an unusual combination of properties, including extremely high melting temperatures (>3000°C), high hardness, and good chemical stability and strength at high temperatures. Typical UHTC materials are the carbides, nitrides, and borides of transition metals, but the Group IV compounds (Ti, Zr, Hf) plus TaC are generally considered to be the main focus of research due to the superior melting temperatures and stable high-melting temperature oxide that forms in situ. Rather than focusing on the latest scientific results, Ultra-High Temperature Ceramics: Materials for Extreme Environment Applications broadly and critically combines the historical aspects and the state-of-the-art on the processing, densification, properties, and performance of boride and carbide ceramics. In reviewing the historic studies and recent progress in the field, Ultra-High Temperature Ceramics: Materials for Extreme Environment Applications provides: Original reviews of research conducted in the 1960s and 70s Content on electronic structure, synthesis, powder processing, densification, property measurement, and characterization of boride and carbide ceramics. Emphasis on materials for hypersonic aerospace applications such as wing leading edges and propulsion components for vehicles traveling faster than Mach 5 Information on materials used in the extreme environments associated with high speed cutting tools and nuclear power generation Contributions are based on presentations by leading research groups at the conference "Ultra-High Temperature Ceramics: Materials for Extreme Environment Applications II" held May 13-19, 2012 in Hernstein, Austria. Bringing together disparate researchers from academia, government, and industry in a singular forum, the meeting cultivated didactic discussions and efforts between bench researchers, designers and engineers in assaying results in a broader context and moving the technology forward toward near- and long-term use. This book is useful for furnace manufacturers, aerospace manufacturers that may be pursuing hypersonic technology, researchers studying any aspect of boride and carbide ceramics, and practitioners of high-temperature structural ceramics.

Download or read book High Temperature Materials and Mechanisms written by Yoseph Bar-Cohen and published by CRC Press. This book was released on 2014-03-03 with total page 562 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of high-temperature materials in current and future applications, including silicone materials for handling hot foods and metal alloys for developing high-speed aircraft and spacecraft systems, has generated a growing interest in high-temperature technologies. High Temperature Materials and Mechanisms explores a broad range of issues relate

Download or read book Spark Plasma Sintering written by Giacomo Cao and published by Elsevier. This book was released on 2019-06-12 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spark Plasma Sintering: Current Status, New Developments and Challenges looks at the progress made in the field of SPS. It includes a review of the scientific mechanisms, materials synthesis and industry applications for this processing technique. Chapters are written by leading experts in the field, encompassing topics surrounding the densification mechanism and microstructure evolution, the classification of high-performance materials, a review of numerical simulation, discussions of new technology advances, such as HP-SPS, flash sintering and related challenges. This book will be useful for researchers, engineers and students within the materials science and engineering fields.

Download or read book High Entropy Materials written by Huimin Xiang and published by John Wiley & Sons. This book was released on 2023-01-11 with total page 277 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-Entropy Materials Significant update of knowledge in the field of high-entropy materials, including promising new high-entropy ceramics High-Entropy Materials provides information on state-of-the-art development in the field of high-entropy materials, including high-entropy alloys, high-entropy ceramics, and a variety of their applications, covering many core topics to provide a thorough and detailed overview of the subject. The book also thoroughly explores the applications of high-entropy materials in various areas, such as EBC/TBC coating, superhard and wear resistance coating, nuclear energy, batteries, catalysts, thermoelectric, supercapacitors, biocompatible structure, and microelectronics. In High-Entropy Materials, readers can expect to find specific information on: Basics of high entropy materials, structural features and thermodynamics of high-entropy materials, and theoretical design in high-entropy materials Synthesis and processing of high-entropy materials and characterization of high-entropy materials, as well as their mechanical and functional properties Challenges and future directions of high-entropy materials, a relatively new type of material that has been in development only since the early 2000s How high-entropy materials are a horizon-broadening class of materials that can significantly further humanity’s pursuit of progress Focusing on the fundamentals and developments of high-entropy alloys and ceramics as well as on their microstructure and properties for a wide range of applications, High-Entropy Materials is an essential resource on the subject for materials scientists, metallurgists, mechanical engineers, and professionals in the aerospace industries.

Download or read book Electric Refractory Materials written by Yukinobu Kumashiro and published by CRC Press. This book was released on 2000-08-24 with total page 778 pages. Available in PDF, EPUB and Kindle. Book excerpt: An exploration of electric refractory materials, this book covers developments of blue light-emitting diodes using GaN-based nitrides for laser and high-temperature and -frequency devices. Electric Refractory Materials introduces growth and evaluation standards of films and bulk crystals, with consideration of band structure, surface electronic structure, and lattice vibrations. It also covers heat capacity and thermal conductivity, irradiation properties, and selective surfaces. Focusing on diamond material, the book examines its synthesis and characterization as well as its electrical, optical, and conductive properties. The book also discusses the use of silicon carbide, boron compounds, and other material used in electronic and light-emitting devices.

Download or read book Energy Research Abstracts written by and published by . This book was released on 1990 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Handbook of Ceramic Composites written by Narottam P. Bansal and published by Springer Science & Business Media. This book was released on 2006-08-25 with total page 547 pages. Available in PDF, EPUB and Kindle. Book excerpt: This valuable handbook has been compiled by internationally renowned researchers in the field. Each chapter is focused on a specific composite system or a class of composites, presenting a detailed description of processing, properties, and applications.

Download or read book Handbook of Physical Vapor Deposition PVD Processing written by D. M. Mattox and published by Cambridge University Press. This book was released on 2014-09-19 with total page 947 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers all aspects of physical vapor deposition (PVD) process technology from the characterizing and preparing the substrate material, through deposition processing and film characterization, to post-deposition processing. The emphasis of the book is on the aspects of the process flow that are critical to economical deposition of films that can meet the required performance specifications. The book covers subjects seldom treated in the literature: substrate characterization, adhesion, cleaning and the processing. The book also covers the widely discussed subjects of vacuum technology and the fundamentals of individual deposition processes. However, the author uniquely relates these topics to the practical issues that arise in PVD processing, such as contamination control and film growth effects, which are also rarely discussed in the literature. In bringing these subjects together in one book, the reader can understand the interrelationship between various aspects of the film deposition processing and the resulting film properties. The author draws upon his long experience with developing PVD processes and troubleshooting the processes in the manufacturing environment, to provide useful hints for not only avoiding problems, but also for solving problems when they arise. He uses actual experiences, called ""war stories"", to emphasize certain points. Special formatting of the text allows a reader who is already knowledgeable in the subject to scan through a section and find discussions that are of particular interest. The author has tried to make the subject index as useful as possible so that the reader can rapidly go to sections of particular interest. Extensive references allow the reader to pursue subjects in greater detail if desired. The book is intended to be both an introduction for those who are new to the field and a valuable resource to those already in the field. The discussion of transferring technology between R&D and manufacturing provided in Appendix 1, will be of special interest to the manager or engineer responsible for moving a PVD product and process from R&D into production. Appendix 2 has an extensive listing of periodical publications and professional societies that relate to PVD processing. The extensive Glossary of Terms and Acronyms provided in Appendix 3 will be of particular use to students and to those not fully conversant with the terminology of PVD processing or with the English language.

Download or read book High Entropy Materials written by Anuj Kumar and published by CRC Press. This book was released on 2024-07-25 with total page 327 pages. Available in PDF, EPUB and Kindle. Book excerpt: High Entropy Materials covers the fundamental concepts of these materials and their emerging applications. To fulfil growing energy demand, scientists are looking for novel materials which can be used for the fabrication of high-performance energy devices. Many materials such as graphene, carbon nanotubes, and metal oxides are used in energy production and storage. A new class of metal oxides, multicomponent metal oxides, known as high entropy materials, have attracted considerable attention not only for their energy applications but also other emerging applications such as use in sensors, catalysts, and CO2 absorption. Key Features: Reviews state-of-the-art developments Provides new directions to scientists, researchers, and students to better understand the principles, technologies, and applications of high entropy materials Discusses ongoing challenges and visions for the future

Download or read book Japanese Technical Abstracts written by and published by . This book was released on 1988 with total page 572 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nanostructured intermetallics from rational synthesis to energy electrocatalysis written by Mingcheng Zhang and published by OAE Publishing Inc.. This book was released on 2023-06-05 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: Intermetallics are a large family of structurally ordered alloys that combines a metal element with other metal/metalloid elements with a clearly defined stoichiometric ratio. Intermetallics possess abundant crystal structures and atomic packing motifs, giving rise to a great variety of electronic configurations and surface adsorption properties. The wide electronic and geometric diversity makes intermetallics a highly promising population for discovering advanced materials for various catalytic applications. This review presents recent advances in the reaction synthesis of intermetallic materials at the nanoscale and their energy-related electrocatalytic applications. Initially, we introduce general principles for the formation of stable intermetallic structures. Subsequently, we elaborate on common synthetic strategies of nanostructured intermetallics, such as thermal annealing, wet-chemical methods, metallothermic reduction, and template-directed synthesis. Furthermore, we discuss the wide employment of these intermetallic nanocatalysts in many different kinds of electrocatalytic applications, as well as highlight the theoretical and experimental evidence for establishing a reasonable relationship between atomic arrangement and catalytic activity. Finally, we propose some perspectives for future developments of intermetallic preparation and catalytic applications.

Download or read book High Entropy Materials written by Yong Zhang and published by CRC Press. This book was released on 2023-08-09 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research in the field of high-entropy materials is advancing rapidly. High-Entropy Materials: Advances and Applications focuses on materials discovered using the high-entropy alloys (HEA) strategy. It discusses various types of high-entropy materials, such as face-centered cubic (FCC) and body-centered cubic (BCC) HEAs, films and coatings, fibers, and powders and hard-cemented carbides, along with current research status and applications: • Describes, compositions and processing of high-entropy materials. • Summarizes industrially valuable alloys found in high-entropy materials that hold promise for promotion and application. • Explains how high-entropy materials can be used in many fields and can outperform traditional materials. This book is aimed at researchers, advanced students, and academics in materials science and engineering and related disciplines.