Densification Of Rapid Carbothermal Synthesized And Commercial Boron Carbide By Spark Plasma Sintering
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Densification Of Rapid Carbothermal Synthesized And Commercial Boron Carbide By Spark Plasma Sintering
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Author : Muhammet Fatih Toksoy
language : en
Publisher:
Release Date : 2014
Densification Of Rapid Carbothermal Synthesized And Commercial Boron Carbide By Spark Plasma Sintering written by Muhammet Fatih Toksoy and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Boron categories.
Boron carbide is a structural ceramic material with exceptionally good physical and chemical properties. Thus, boron carbide is proposed for applications in extreme conditions. However synthesizing and sintering of boron carbide is extremely difficult due to its high melting point and strong covalent bonding. Secondary phases, non-uniform composition, complex stoichiometry and powder morphology are problems in most commercial powders as a result of synthesis and powder preparation procedures. Achieving more than 90% TD is difficult due to strong covalent bonding structure and low plasticity of boron carbide. Very high sintering temperatures that approach the melting point are needed for densification. This dissertation seeks to establish an improved understanding on Spark Plasma Sintering (SPS) behaviors of boron carbide and effects of powder properties on final products. Rapid carbothermal reduction (RCR) method was utilized to synthesize boron carbide powder. Submicron boron carbide powders with narrow particle size distribution were synthesized. Free carbon was significantly reduced and near B4C stoichiometry was achieved. Commercial boron carbide powders were also modified by processing in the RCR reactor. Free carbon was reduced to trace amounts; powder morphology and stoichiometry was modified. Commercial, synthesized and modified boron carbide powders were analyzed and characterized using X-Ray diffraction (XRD), electron microscopy, particle size analysis and chemical analyses. Synthesized boron carbide powder had smaller particle size, lower free carbon levels and increased concentration of twinning compared to commercial samples. Standard sintering procedure for boron carbide was established for SPS. Powders were sintered to different temperatures with various dwell times to analyze sintering behavior of boron carbide on SPS without any additives. Synthesized boron carbide powders reached +99% TD at lower temperature and shorter dwell times compared to commercial boron carbide samples. Highly dense materials were produced with limited grain growth. Dense samples were analyzed by XRD and electron microscopy. Knoop hardness tests were applied to dense boron carbide samples. Hardness results showed an improvement with RCR synthesized powders. Results were correlated and powder-sintering-final properties relations were established.
Advances In Ceramic Armor Ix Volume 34 Issue 5
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Author : Jerry C. LaSalvia
language : en
Publisher: John Wiley & Sons
Release Date : 2013-11-04
Advances In Ceramic Armor Ix Volume 34 Issue 5 written by Jerry C. LaSalvia and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-11-04 with Technology & Engineering categories.
Ceramic Engineering and Science Proceedings Volume 34, Issue 5 - Advances in Ceramic Armor IX A collection of 14 papers from The American Ceramic Society's 37th International Conference on Advanced Ceramics and Composites, held in Daytona Beach, Florida, January 27-February 1, 2013.This issue includes papers presented in the Armor Ceramics Symposium on topics such as Manufacturing; High-Rate Real-Time Characterization; Microstructural Design; Nondestructive Characterization; and Phenomenology and Mechanics of Ceramics Subjected to Ballistic Impact.
Advances In Ceramic Armor X Volume 35 Issue 4
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Author : Jerry C. LaSalvia
language : en
Publisher: John Wiley & Sons
Release Date : 2015-01-28
Advances In Ceramic Armor X Volume 35 Issue 4 written by Jerry C. LaSalvia and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-01-28 with Technology & Engineering categories.
A collection of 14 papers from the Armor Ceramics symposium held during The American Ceramic Society's 38th International Conference on Advanced Ceramics and Composites, held in Daytona Beach, Florida, January 26-31, 2014.
Evaluating The Effect Of Powder Oxygen Content On The Microstructure And Mechanical Properties Of Silicon Carbide Densified By Spark Plasma Sintering
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Author : Vincent Alexander DeLucca
language : en
Publisher:
Release Date : 2017
Evaluating The Effect Of Powder Oxygen Content On The Microstructure And Mechanical Properties Of Silicon Carbide Densified By Spark Plasma Sintering written by Vincent Alexander DeLucca and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with Silicon carbide categories.
Silicon carbide (SiC) is an important material in industry due to its favorable mechanical, thermal, chemical, and electrical properties. While it has been mainly used as an abrasive material in the past, more modern applications like armor and other structural applications, often require densified ceramic bodies. SiC powders can be densified in a number of ways, but one common method is solid-state sintering, either with or without applied pressure. It is well known that in the presence of oxygen, pure SiC will form a passivating oxide layer of silica (SiO2) on its surface. This poses a problem in sintering as SiO2 can inhibit the densification of solid state sintered SiC. This thesis examines the effects of varying oxygen content levels in silicon carbide powders on the microstructure and mechanical properties of the resulting densified bodies after solid state sintering via the spark plasma sintering (SPS) method. Two commercial SiC powders were obtained, characterized, and treated to introduce a range of different oxygen content levels. These powders were then densified via the spark plasma sintering method using boron carbide and carbon additives to produce dense samples. Three series of samples were made using each powder, one varying the amount of carbon added as a particulate, one varying the amount of carbon added as a liquid resin, and one where the oxygen content of the powder was directly manipulated by HF washing, aging, or heat treating. The dense SiC samples were then characterized to determine the effect of the powder's oxygen content on the microstructure and mechanical properties. The samples were examined using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), Knoop microhardness testing, and nondestructive ultrasonic evaluation techniques including acoustic spectroscopy and conventional NDE methods. SEM and EBSD analysis revealed that changes in the powder oxygen content can result in a number of microstructural effects. At intermediate oxygen levels, exaggerated grain growth can occur resulting in large plate-like grains, accompanied by a transformation from the 6H to 4H SiC polytype. At higher oxygen levels, densification may be inhibited and at very high oxygen contents formation of an oxygen rich secondary phase can occur. Varying the oxygen content of the SiC powder also significantly affects the mechanical properties of the dense ceramic. Ultrasonic measurements of the elastic properties showed a clear decrease in the elastic moduli as the oxygen content is increased. Knoop microhardness measurements show similar behavior with a reduction in hardness with increased powder oxygen content.
Time Resolved In Situ Analysis Of Densification Of Nano Boron Carbide Under Superimposed Electric And Thermal Fields With Energy Dispersive X Ray Diffraction
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Author : Hulya Bicer
language : en
Publisher:
Release Date : 2016
Time Resolved In Situ Analysis Of Densification Of Nano Boron Carbide Under Superimposed Electric And Thermal Fields With Energy Dispersive X Ray Diffraction written by Hulya Bicer and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with Boron categories.
Boron carbide (B4C) is characterized by high melting temperature, high hardness, and low density. Such exceptional properties make B4C is an important covalent solid which is considered the foremost material of choice for high-technology applications. However, low diffusivity caused by the highly directional and stiff character of the covalent bond makes the thermally activated sintering of B4C difficult. Highly covalent bonded ceramics are sintered with hot pressing and spark plasma sintering (SPS) to achieve high densities. However, these two techniques are limited to simple shape components and costly, involving expensive equipment. Pressureless sintering of B4C is desired to avoid expensive die designs and post sintering diamond machining, but very high sintering temperatures close to melting point is necessary to obtain high densities. Recently introduced flash sintering technique is a low voltage two electrode method which enhances the densification of ceramics. The sintering time and temperature can be reduced substantially with flash sintering that provide essential energy savings. In this study, the feasibility of flash sintering of nanoparticulate boron carbide is investigated. Firstly, we analyze the thermal expansion of boron carbide under different constant electric field strength to obtain fundamental data to provide insight into understanding of flash sintering. The electric field strength has an effect on the non-linear thermal expansion coefficients of B4C, and expansion becomes more non-linear with the increase of applied e-field. Secondly, the variety of non-isothermal and isothermal flash sintering experiments have been performed to achieve densification of B4C. By using low voltage, densities up to 95% of the theoretical density have been accomplished at temperatures as low as 711oC and short times on the order of few minutes. The very low process densification temperatures and time clearly indicate that mass transport in this nanoparticulate system under the action of both thermal and electrical fields are of an electrochemical origin. The implementation of ultrahigh energy EDXRD method in flash sintering of B4C enables us to monitor the evolution of nanoparticulate matter at the unit cell scale that is otherwise not possible with conventional Bragg-Brentano-method. EDXRD analysis reveals the transient anomalous unit cell expansion which is consistent with the flash sintering phenomena, and we demonstrate that flash sintering of B4C is possible with help of new coupling mechanism called the galvanomechanical effect. Moreover, we investigate the effect of different flash sintering conditions on densification of B4C.
Boron And Refractory Borides
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Author : G.V. Samsonov
language : en
Publisher: Springer Science & Business Media
Release Date : 2012-12-06
Boron And Refractory Borides written by G.V. Samsonov and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-06 with Science categories.
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.
Xxii Convegno Nazionale Igf Acta Fracturae
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Author :
language : en
Publisher: Gruppo Italiano Frattura
Release Date :
Xxii Convegno Nazionale Igf Acta Fracturae written by and has been published by Gruppo Italiano Frattura this book supported file pdf, txt, epub, kindle and other format this book has been release on with categories.
Max Phases And Ultra High Temperature Ceramics For Extreme Environments
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Author : It-Meng Low
language : en
Publisher: Engineering Science Reference
Release Date : 2013
Max Phases And Ultra High Temperature Ceramics For Extreme Environments written by It-Meng Low and has been published by Engineering Science Reference this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with Ceramic-matrix composites categories.
"This book investigates a new class of ultra-durable ceramic materials, which exhibit characteristics of both ceramics and metals, and will explore recent advances in the manufacturing of ceramic materials that improve their durability and other physical properties, enhancing their overall usability and cost-effectiveness"--
Ultra High Temperature Ceramics
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Author : William G. Fahrenholtz
language : en
Publisher: John Wiley & Sons
Release Date : 2014-10-10
Ultra High Temperature Ceramics written by William G. Fahrenholtz and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-10-10 with Technology & Engineering categories.
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.
Spark Plasma Sintering Current Status New Developments And Challenges
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Author : Giacomo Cao
language : en
Publisher: Elsevier
Release Date : 2019-06-17
Spark Plasma Sintering Current Status New Developments And Challenges written by Giacomo Cao and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-06-17 with Technology & Engineering categories.
Spark Plasma Sintering: Current Status, New Developments and Challenges: A Review of the Current Trends in SPS 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. Provides significant information on the most relevant research topics currently being addressed by the SPS community Highlights the application of SPS techniques Reviews critical issues that still need to be overcome when utilizing SPS technology