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Book Heat Treatment Effects on Microstructure of SiC Fiber Preforms

Download or read book Heat Treatment Effects on Microstructure of SiC Fiber Preforms written by and published by . This book was released on 1999 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Preforms of BN/SiC coated Sylramic SiC fibers were heat treated at 1420 deg, 1600 deg, and 1800 deg C in 0.1 MPa argon or at 1800 deg C in 103 MPa nitrogen for 1 h. Optical, SEM, and TEM techniques were used to analyze the effects of environmental exposure on constituent microstructure of the preforms. TEM analysis of the as-received preforms indicates that the CVI BN coating is predominantly amorphous with small amounts of microcrystalline BN grains, and that the SiC coating on top of the BN coating and SiC fibers is polycrystalline. With increasing temperature of exposure from 1420 deg to 1800 deg C, the preforms heat treated in argon showed increasing amounts of crystalline BN in the CVI BN coating, and coarsening of SiC grains in the CVI SiC coating and SiC fibers. On the other hand, the preforms heal treated in 103 MPa nitrogen at 1800 deg C for 1 h showed microstructural changes inside the fiber tows similar to those heat treated at 1800 deg C in 0.1 MPa argon for 1 h, but the same preforms on the outer periphery of the tows showed reaction between nitrogen and the CVI SiC coating to form Si3N4.

Book Effects of High Temperature Argon Heat Treatment on Tensile Strength and Microstructure of BN SiC Coated SiC Fiber Preforms

Download or read book Effects of High Temperature Argon Heat Treatment on Tensile Strength and Microstructure of BN SiC Coated SiC Fiber Preforms written by and published by . This book was released on 1999 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Preforms of BN/SiC coated Hi-Nicalon and Sylramic SiC fibers were heat treated under 0.1 MPa argon pressure between 1000 deg to 1800 deg C for 1 and 100h. The effects of high temperature exposure on physical dimensions, weight, room temperature tensile strength, and microstructure of preforms have been studied. Both preforms showed shrinkage and weight loss, and microstructural changes beyond 1000 deg C. After 100 hr exposure, the Hi-Nicalon preforms showed strength degradation beyond 1200 deg C. The mechanisms of the strength degradation appear to be grain growth of the SiC fibers and crystallization of the BN coating. After 100 hr, the Sylramic preforms heat treated to 1000 deg C retained their as-produced strength while some of those heat-treated between 1000 deg and 1800 deg C showed strength degradation and others did not. At 1800 deg C, the ultimate tensile strength decreased with increasing time of exposure. Reasons for strength degradation of Sylramic preforms are being investigated.

Book Effect of Microstructure on the Thermomechanical Properties of SiC Fibers

Download or read book Effect of Microstructure on the Thermomechanical Properties of SiC Fibers written by and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of non-oxidizing heat treatments on the creep resistance and strength retention for carbon-rich and near-stoichiometric SiC-based fibers was investigated. Carbon-rich fibers showed excellent strength retention and greatly improved creep resistance when heat treated at 1700 deg C in argon. This was attributed to the increased grain sizes and possibly more highly crystallized graphitic carbon. The measured creep resistance was comparable to or better than observed for as-prepared near-stoichiometric fibers. This result indicated that diffusion is inhibited in SiC-based fibers which contain larger amounts of excess carbon. The creep resistance of the near-stoichiometric fibers was also greatly enhanced by annealing heat treatments at 1940 deg C. This was attributed to increased grain size and possibly to reduced boron concentration within the bulk fiber. The combination of high strength (approximately equal 3 GPa) and high creep resistance that was obtained for the annealed near-stoichiometric fibers has not been observed for other SiC based fibers.

Book Chemical Vapour Deposition CVD

Download or read book Chemical Vapour Deposition CVD written by Kwang-Leong Choy and published by CRC Press. This book was released on 2019-06-07 with total page 417 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers a timely and complete overview on chemical vapour deposition (CVD) and its variants for the processing of nanoparticles, nanowires, nanotubes, nanocomposite coatings, thin and thick films, and composites. Chapters discuss key aspects, from processing, material structure and properties to practical use, cost considerations, versatility, and sustainability. The author presents a comprehensive overview of CVD and its potential in producing high performance, cost-effective nanomaterials and thin and thick films. Features Provides an up-to-date introduction to CVD technology for the fabrication of nanomaterials, nanostructured films, and composite coatings Discusses processing, structure, functionalization, properties, and use in clean energy, engineering, and biomedical grand challenges Covers thin and thick films and composites Compares CVD with other processing techniques in terms of structure/properties, cost, versatility, and sustainability Kwang-Leong Choy is the Director of the UCL Centre for Materials Discovery and Professor of Materials Discovery in the Institute for Materials Discovery at the University College London. She earned her D.Phil. from the University of Oxford, and is the recipient of numerous honors including the Hetherington Prize, Oxford Metallurgical Society Award, and Grunfeld Medal and Prize from the Institute of Materials (UK). She is an elected fellow of the Institute of Materials, Minerals and Mining, and the Royal Society of Chemistry.

Book Advances in Ceramic matrix Composites

Download or read book Advances in Ceramic matrix Composites written by and published by . This book was released on 2001 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Microstructural and Strength Stability of a Developmental CVD SiC Fiber

Download or read book Microstructural and Strength Stability of a Developmental CVD SiC Fiber written by Ramakrishna T. Bhatt and published by . This book was released on 1995 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Thermal Effects on the Mechanical Properties of SiC Fiber Reinforced Reaction Bonded Silicon Nitride Matrix SiC RBSN Composites

Download or read book Thermal Effects on the Mechanical Properties of SiC Fiber Reinforced Reaction Bonded Silicon Nitride Matrix SiC RBSN Composites written by R. T. Bhatt and published by . This book was released on 1988 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: The elevated temperature four-point flexural strength and the room temperature tensile and flexural strength properties after thermal shock were measured for ceramic composites consisting of 30 vol % uniaxially aligned 142 microns diameter SiC fibers in a reaction bonded Si3N4 matrix. The elevated temperature strengths were measured after 15 min of exposure in air at temperatures to 1400 C. The thermal shock treatment was accomplished by heating the composite in air for 15 min at temperatures to 1200 C and then quenching in water at 25 C. The results indicate no significant loss in strength properties either at temperature or after thermal shock when compared with the strength data for composites in the as-fabricated condition. (jes).

Book Annual Meeting Abstracts

Download or read book Annual Meeting Abstracts written by American Ceramic Society. Meeting and published by . This book was released on 1999 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Advances in High Temperature Ceramic Matrix Composites and Materials for Sustainable Development

Download or read book Advances in High Temperature Ceramic Matrix Composites and Materials for Sustainable Development written by Mrityunjay Singh and published by John Wiley & Sons. This book was released on 2017-06-29 with total page 693 pages. Available in PDF, EPUB and Kindle. Book excerpt: Global population growth and tremendous economic development has brought us to the crossroads of long-term sustainability and risk of irreversible changes in the ecosystem. Energy efficient and ecofriendly technologies and systems are critically needed for further growth and sustainable development. While ceramic matrix composites were originally developed to overcome problems associated with the brittle nature of monolithic ceramics, today the composites can be tailored for customized purposes and offer energy efficient and ecofriendly applications, including aerospace, ground transportation, and power generation systems. The 9th International Conference on High Temperature Ceramic Matrix Composites (HTCMC 9) was held in Toronto, Canada, June 26-30, 2016 to discuss challenges and opportunities in manufacturing, commercialization, and applications for these important material systems. The Global Forum on Advanced Materials and Technologies for Sustainable Development (GFMAT 2016) was held in conjunction with HTCMC 9 to address key issues, challenges, and opportunities in a variety of advanced materials and technologies that are critically needed for sustainable societal development. This Ceramic Transactions volume contains a collection of peer reviewed papers from the 16 below symposia that were submitted from these two conferences Design and Development of Advanced Ceramic Fibers, Interfaces, and Interphases in Composites- A Symposium in Honor of Professor Roger Naslain Innovative Design, Advanced Processing, and Manufacturing Technologies Materials for Extreme Environments: Ultrahigh Temperature Ceramics (UHTCs) and Nano-laminated Ternary Carbides and Nitrides (MAX Phases) Polymer Derived Ceramics and Composites Advanced Thermal and Environmental Barrier Coatings: Processing, Properties, and Applications Thermomechanical Behavior and Performance of Composites Ceramic Integration and Additive Manufacturing Technologies Component Testing and Evaluation of Composites CMC Applications in Transportation and Industrial Systems Powder Processing Innovation and Technologies for Advanced Materials and Sustainable Development Novel, Green, and Strategic Processing and Manufacturing Technologies Ceramics for Sustainable Infrastructure: Geopolymers and Sustainable Composites Advanced Materials, Technologies, and Devices for Electro-optical and Medical Applications Porous Ceramics for Advanced Applications Through Innovative Processing Multifunctional Coatings for Sustainable Energy and Environmental Applications

Book Impact of Heat Treatment and Oxidation of Carbon carbon Composites on Microstructure and Physical Properties

Download or read book Impact of Heat Treatment and Oxidation of Carbon carbon Composites on Microstructure and Physical Properties written by Sardar Sarwat Iqbal and published by . This book was released on 2011 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon-carbon (C/C) composites are notable among engineering materials in aerospace and defense industries possessing excellent specific mechanical, thermal, frictional and wear properties. C/C maintain their properties at temperatures where most of the high end alloys give in, and maintain their dimensional stability at temperatures above 2000 °C. C/C is frequently used in aircraft and automotive industries as brake materials. However, frictional performance is dependent on various parameters: microstructure, fiber type, fiber orientation distribution, fiber/matrix interfacial bond, heat treatment, and oxidation. The present study in dissertation provides an insight into the impact of heat treatment, and oxidation on microstructure, mechanical and thermal properties. The study demonstrated a highly inhomogeneous nature of C/C, and sample size is a very important parameter in governing mechanical properties. Since, the slightest change in the dimension of samples could bring about a radically different outcome in terms of mechanical properties, and can hardly be representative of the bulk properties. Therefore, in order to obtain a good estimate of the bulk properties, the sample size must be comparable to the bulk material. The research nonetheless showed the impact of sample size in estimating the mechanical properties of bulk properties, which are highly significant after statistical analysis, and, therefore, it must be taken into account to understand the processing-structure-property-analysis relationships.

Book Microstructure and Tensile Properties of BN SiC Coated Hi Nicalon and Sylramic SiC Fiber Preforms

Download or read book Microstructure and Tensile Properties of BN SiC Coated Hi Nicalon and Sylramic SiC Fiber Preforms written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-19 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: Batch to batch and within batch variations, and the influence of fiber architecture on room temperature physical and tensile properties of BN/SiC coated Hi-Nicalon and Sylramic SiC fiber preform specimens were determined. The three fiber architectures studied were plain weave (PW), 5-harness satin (5HS) and 8-harness satin (8HS) Results indicate that the physical properties vary up to 10 percent within a batch, and up to 20 percent between batches of preforms. Load-reload (Hysteresis) and acoustic emission methods were used to analyze damage accumulation occurring during tensile loading. Early acoustic emission activity, before observable hysteretic behavior, indicates that the damage starts with the formation of nonbridged tunnel cracks. These cracks then propagate and intersect the load bearing "0" fibers giving rise to hysteretic behavior, For the Hi-Nicalon preform specimens, the onset of "0" bundle cracking stress and strain appeared to be independent of the fiber architecture. Also, the "0" fiber bundle cracking strain remained nearly the same for the preform specimens of both fiber types. Transmission Electron Microscope (TEM) analysis indicates that the Chemical Vapor Infiltration (CVI) Boron Nitride (BN) interface coating is mostly amorphous and contains carbon and oxygen impurities, and the CVI SiC coating is crystalline. No reaction exists between the CVI BN and SiC coating. Bhatt, Ramakrishna T. and Chen, Yuan L. and Morscher, Gregory N. Glenn Research Center NASA/TM-2001-210695, NAS 1.15:210695, E-12626