Download or read book Grain Boundary Energetics in Non Oxide Ceramics written by A. H. Heuer and published by . This book was released on 1978 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research on 'Grain Boundary Energetics in Non-Oxide Ceramics' has been conducted at CWRU since 1975 and has concentrated on two specific areas--the beta to alpha transformation in polycrystalline SiC, and the nature of grain boundary phases in hot-pressed Si3N4 containing various densification aids. The beta to alpha transformation in polycrystalline SiC is unusual in that it appears to occur in two stages. The first involves the growth of composite plates consisting of alpha-SiC plates sandwiched between recrystallized envelopes of beta SiC. This stage ends when the original polycrystalline beta matrix is consumed. The second and more sluggish stages involves the thickening of the alpha plates within their beta envelopes and requires repeated piecewise nucleation of alpha at the beta to alpha interface. High resolution TEM has been used to show that the commercial MgO-doped hot-pressed Si3N4 apparently contains a continuous grain boundary phase that is responsible for the poor high-temperature performance. Grain boundary microstructures have been characterized in polycrystalline Si3N4 containing Y2C3, ZrO2, and BeSiN2; the latter additive appears to be the most promising, since a continuous grain boundary film is not present. (Author).
Download or read book Grain Boundary Energy as the Design Parameter for Nanocrystalline Oxide Ceramic Materials written by Arseniy Bokov and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The present work establishes that grain boundary energies in nanocrystalline oxide ceramics can be considered as a separate materials design variable along, while interconnected, with composition, processing conditions, crystallographic phase, and microstructure. The importance of this variable is discussed in terms of its interrelation with mechanical and functional properties measured at the macroscale. Grain boundary energy can be controlled through thermodynamically-driven dopant segregation, in which specific elements preferentially occupy the sites located at the grain boundary region. The present study showcases this concept using segregation of La in cubic yttria-stabilized zirconia (YSZ) as an example. Lanthanum atoms segregated at the grain boundaries of YSZ are observed to form longer bonds with oxygen ions which leads to a slight change of oxygen positions for better accommodation of the host cations, causing the grain boundary energy of the material to decrease on average. This dissertation demonstrates that such control over grain boundary energy can increase fracture toughness by about 20% and decrease grain boundary resistance to ionic transport by 50-100%. In both cases, the improvement is driven by narrow distribution of grain boundary energies. The dopant atoms tend to preferentially populate boundaries with high grain boundary energy which have a large number of unsatisfied bonds. As a result, the fraction of high-energy boundaries decreases, relatively increasing the population of low energy ones. From the fracture toughness perspective, thermodynamic segregation of dopant increases the strength of individual grain boundaries and promotes deflection and branching of cracks. From the perspective of ionic conductivity, doping mitigates grain boundary blocking and increases the probability for oxygen ion to encounter a grain boundary with low resistance to charge transport. Besides advancements in dopant segregation, this work provides experimental evidence that grain boundary energy is also a function of grain size. The conventional ceramic with coarse-grained microstructure is typically populated with the most stable grain boundary configurations. The reduction in grain size, however, causes the majority of the grain boundaries to have a high energy configuration, which is likely related to structural discontinuities, effects of triple junctions, and interface kink effects. For example, the value of grain boundary energy for YSZ with relatively large grains is about 0.55 ± 0.04 J/m2, but it increases up to 0.84 ± 0.04 J/m2 when approaching grain sizes of about 16 nm. As a consequence to macroscale properties, this is responsible for lowering the average strength of interfaces, causing a decrease in hardness driven by the facilitated activation of quasi-plastic response in the form of shear and sliding of the entire grains once the grain boundaries become weaker. The observed relationships and phenomena are described in more detail in the dissertation which follows. The results of this work are largely obtained by the author through 352 spark plasma sintering experiments, 194 runs of X-ray powder diffraction, 1021 images of scanning electron microscopy, and many labor-hours on other instruments.
Download or read book The Role of Grain Boundaries and Surfaces in Ceramics written by W. Wurth Kriegel and published by Springer. This book was released on 1966 with total page 664 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Grain Boundary Engineering in Ceramics written by Taketo Sakuma and published by Wiley-American Ceramic Society. This book was released on 2000-06-28 with total page 638 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the key technologies needed to understand and develop the mechanical and electrical properties of ceramics is the field of grain boundary engineering. This book covers new developments in this important field and addresses topics from grain boundary phenomena to grain boundary quantum structures, including the development of new techniques such as multifunctional electronmicroscopes, various kinds of spectroscopic analysis, and first principles calculations. Proceedings of the Japan Fine Ceramics Center Workshop, March 15-17, 2000, in Nagoya, Japan; Ceramic Transactions, Volume 118.
Download or read book Grain Boundaries and Interfacial Phenomena in Electronic Ceramics written by Lionel M. Levinson and published by . This book was released on 1994 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt: The proceedings of the November 1990 symposium, held in conjunction with the PAC RIM Meeting, comprise papers organized under five headings: overview (5 papers); ferrites and titanates (13 papers); varistors and conductors (9 papers); high-temperature superconductors (4 papers); and processing and c
Download or read book Non Stoichiometric Compounds written by J. Nowotny and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 574 pages. Available in PDF, EPUB and Kindle. Book excerpt: The material in this book is based on invited and contributed pa pers presented at the NATO Advanced Research Workshop on INon-stoichio l metric Compounds held in Ringberg Castle, Rottach-Egern (Bavarian Alps), Germany, July 3-9, 1988. The workshop followed previous meetings held in Mogilany, Poland (1980), Alenya, France (1982), Penn State, USA (1984) and Keele University, UK (1986). The aim of these workshops is to present and discuss up-to-date knowledge in the study of non-stoichiometry and its effect on materials properties as well as to indicate the most urgent research pathways required in this field. Since the subject of non-stoichiometry is interdisciplinary, the workshops bring together solid state physicists and chemists, surface scientists, materials scientists, ceramists and metallurgists. The present workshop, which gathered 42 scientists of an inter national reputation, mainly considered the effect of surfaces, grain boundaries and structural defects on materials properties. From discus sions during this meeting it emerged that correct understanding of properties of ceramic materials requires urgent studies on the defect structure of the interface region. Progress in this direction requires the development of the interface defect chemistry. This is the task for materials scientists in the near future. The present proceedings includes both theoretical and experimen tal work on general aspects of non-stoichiometry, defect structure and diffusion in relation to the bulk and to the interface region of such materials as high tech ceramics, solid electrolytes, electronic cera mics, nuclear materials and high Tc oxide superconductors.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1978 with total page 1018 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Grain Boundary Controlled Properties of Fine Ceramics written by Kozo Ishizaki and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 313 pages. Available in PDF, EPUB and Kindle. Book excerpt: Selected papers presented at the International Workshop on Fine Ceramics 92, Materials Processing and Design through Better Control of Grain Boundaries: Emphasizing Fine Ceramics, held in Nagoya, Japan, 12-13 March 1992.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1978 with total page 762 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book Grain Boundary Phenomena in Electronic Ceramics written by Lionel M. Levinson and published by . This book was released on 1981 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Performance Non Oxide Ceramics II written by R. Haubner and published by Springer Science & Business Media. This book was released on 2002-07-03 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: The nitrides and carbides of boron and silicon are proving to be an excellent choice when selecting materials for the design of devices that are to be employed under particularly demanding environmental and thermal con- tions. The high degree of cross-linking, due to the preferred coordination numbers of the predominantly covalently bonded constituents equalling or exceeding three, lends these non-oxidic ceramics a high kinetic stability, and is regarded as the microscopic origin of their impressive thermal and mechanical durability. Thus it does not come as a surprise that the chemistry, the physical properties and the engineering of the corresponding binary, ternary, and even quaternary compounds have been the subject of intensive and sustained efforts in research and development. In the five reviews presented in the volumes 101 and 102 of "Structure and Bonding" an attempt has been made to cover both the essential and the most recent advances achieved in this particular field of materials research. The scope of the individual contributions is such as to address both graduate students, specializing in ceramic materials, and all scientists in academia or industry dealing with materials research and development. Each review provides, in its introductory part, the chemical, physical and, to some extent, historical background of the respective material, and then focuses on the most relevant and the most recent achievements.
Download or read book Ceramic Microstructures written by Antoni P. Tomsia and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 841 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume, titled Proceedings of the International Materials Symposium on Ce ramic Microstructures: Control at the Atomic Level summarizes the progress that has been achieved during the past decade in understanding and controlling microstructures in ceram ics. A particular emphasis of the symposium, and therefore of this volume, is advances in the characterization, understanding, and control of micro structures at the atomic or near-atomic level. This symposium is the fourth in a series of meetings, held every ten years, devoted to ceramic microstructures. The inaugural meeting took place in 1966, and focussed on the analysis, significance, and production of microstructure; the symposium emphasized the need for, and importance of characterization in achieving a more complete understanding of the physical and chemical characteristics of ceramics. A consensus emerged at that meeting on the critical importance of characterization in achieving a more complete understanding of ceramic properties. That point of view became widely accepted in the ensuing decade. The second meeting took place in 1976 at a time of world-wide energy shortages and thus emphasized energy-related applications of ceramics, and more specifically, microstructure-property relationships of those materials. The third meeting, held in 1986, was devoted to the role that interfaces played both during processing, and in influencing the ultimate properties of single and polyphase ceramics, and ceramic-metal systems.
Download or read book Materials Processing and Design written by Koichi Niihara and published by . This book was released on 1994 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents papers from the workshop on the application of grain boundary phenomena to materials and processing design. Topics covered include electronic materials, evaluation methods, structural materials, and interfaces. Includes an overview of current research in grain-boundary-assisted materials pr
Download or read book Character of Grain Boundaries written by Man F. Yan and published by . This book was released on 1983 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1994-05 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book British Ceramic Abstracts written by and published by . This book was released on 1985 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book February 1 written by E Gutsche and published by Walter de Gruyter GmbH & Co KG. This book was released on 2022-01-19 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt:
