Download or read book Environmental and Heat Treatment Effects on the Strength and Microstructure of 10 to 15um Silicon Carbide Fibers written by Darryl P. Butt and published by . This book was released on 1984 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book Environmental Effects on the Tensile Strength of Chemically Vapor Deposited Silicon Carbide Fibers written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-16 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: The room temperature and elevated temperature tensile strengths of commercially available chemically vapor-deposited (CVD) silicon carbide fibers were measured after 15 min heat treatment to 1600 C in various environments. These environments included oxygen, air, argon and nitrogen at one atmosphere and vacuum at 10/9 atmosphere. Two types of fibers were examined which differed in the SiC content of their carbon-rich coatings. Threshold temperature for fiber strength degradation was observed to be dependent on the as-received fiber-flaw structure, on the environment and on the coating. Fractographic analyses and flexural strength measurements indicate that tensile strength losses were caused by surface degradation. Oxidation of the surface coating is suggested as one possible degradation mechanism. The SiC fibers containing the higher percentage of SiC near the surface of the carbon-rich coating show better strength retention and higher elevated temperature strength. Bhatt, R. T. and Kraitchman, M. D. Glenn Research Center NASA-TM-86981, E-2519, NAS 1.15:86981, USAAVSCOM-TR-85-C-4, AD-A157111 RTOP 533-05-12...
Download or read book Environmental Effects on the Tensile Strength of Chemically Vapor Deposited Silicon Carbide Fibers written by and published by . This book was released on 1985 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The room temperature and elevated temperature tensile strengths of commercially available chemically vapor-deposited silicon carbide fibers were measured after 15 min heat treatment to 1600 C in various environments. These environments included oxygen, air, argon and nitrogen at one atmosphere and vacuum at 10 to the minus 9th power atmosphere. Two types of fibers were examined which differed in the SiC content of their carbon-rich coatings. Threshold temperature for fiber strength degradation was observed to be dependent on the as-received fiber-flaw structure, on the environment and on the coating. Fractographic analyses and flexural strength measurements indicate that tensile strength losses were caused by surface degradation. Oxidation of the surface coating is suggested as one possible degradation mechanism. In general, the SiC fibers containing the higher percentage of SiC near the surface of the carbon rich coating showed better strength retention and higher elevated temperature strength. (Author).
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:
Download or read book Microstructural and Strength Stability of CVD SiC Fibers in Argon Environment written by Ramakrishna T. Bhatt and published by . This book was released on 1991* with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Heat Treatment Effects on the Tensile Properties and Microstructures of a SiC RBSN Composite in Nitrogen written by R. T. Bhatt and published by . This book was released on 1995 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Microstructural Changes in Organically Derived Silicon Carbide Fibers After Heat Treatment written by Thomas J. Paglia and published by . This book was released on 1985 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effect of Microstructure on the Thermomechanical Properties of SIC Fibers written by and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymer-derived SiC-based fibers with fine-diameter (10-15 mm) and high strength (3 GPa) were prepared with carbon-rich and near-stoichiometric compositions. Fiber tensile strengths were determined after heat treatments at temperatures up to 1950 deg C in non-oxidizing atmospheres and up to 1250 deg C in air. The creep resistance of fibers was assessed using bend stress relaxation (BSR) measurements. Fibers showed excellent strength retention after heat treatments in non-oxidiziing atmospheres at temperatures up to 1700 deg C for the carbon-rich fibers and up to 1950 deg C for the near-stoichiometric fibers. The near-stoichiometric fibers also showed considerably better strength retention after heat treatments in air. Creep resistance of the as-fabricated fibers was greatly improved by high-temperature heat treatments. Heat-treated near-stoichiometric fibers could be prepared with 3 GPa tensile strengths and BSR creep behavior which was significantly better than that reported for i-Nicalon TM Type S fibers. It was also shown that the near-stoichiometric fibers could be coated with hexagonal BN using an in-situ processing method.
Download or read book Mechanical Chemical and Microstructural Characterization of Monazite Coated Silicon Carbide Fibers written by Narottam P. Bansal and published by . This book was released on 2000 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tensile strengths of as-received Hi-Nicalon and Sylramic fibers and those having monazite surface coatings, deposited by atmospheric pressure chemical vapor deposition, were measured at room temperature and the Weibull statistical parameters determined. The average tensile strengths of uncoated Hi-Nicalon and Sylramic fibers were 3.19 +/- 0.73 and 2.78 +/- 0.53 GPa with a Weibull modulus of 5.41 and 5.52, respectively. The monazite-coated Hi-Nicalon and Sylramic fibers showed strength loss of approx. 10 and 15 percent, respectively, compared with the as-received fibers. The elemental compositions of the fibers and the coatings were analyzed using scanning Auger microprobe and energy dispersive X-ray spectroscopy. The LaPO4 coating on Hi-Nicalon fibers was approximately stoichiometric and about 50 nm thick. The coating on the Sylramic fibers extended to a depth of about 100 to 150 nm. The coating may have been stoichiometric LaPO4 in the first 30 to 40 nm of the layer. However, the surface roughness of Sylramic fiber made this profile somewhat difficult to interpret. Microstructural analyses of the fibers and the coatings were done by scanning electron microscopy, transmission electron microscopy, and selected area electron diffraction.
Download or read book Modification of Silicon Carbide Fibers for Use in SiC Ti Composites written by and published by . This book was released on 1981 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanical Chemical and Microstructural Characterization of Monazite Coated Silicon Carbide Fibers written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-15 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tensile strengths of as-received Hi-Nicalon and Sylramic fibers and those having monazite surface coatings, deposited by atmospheric pressure chemical vapor deposition, were measured at room temperature and the Weibull statistical parameters determined. The average tensile strengths of uncoated Hi-Nicalon and Sylramic fibers were 3.19 +/- 0.73 and 2.78 +/- 0.53 GPa with a Weibull modulus of 5.41 and 5.52, respectively. The monazite-coated Hi-Nicalon and Sylramic fibers showed strength loss of approx. 10 and 15 percent, respectively, compared with the as-received fibers. The elemental compositions of the fibers and the coatings were analyzed using scanning Auger microprobe and energy dispersive X-ray spectroscopy. The LaPO4 coating on Hi-Nicalon fibers was approximately stoichiometric and about 50 nm thick. The coating on the Sylramic fibers extended to a depth of about 100 to 150 nm. The coating may have been stoichiometric LaPO4 in the first 30 to 40 nm of the layer. However, the surface roughness of Sylramic fiber made this profile somewhat difficult to interpret. Microstructural analyses of the fibers and the coatings were done by scanning electron microscopy, transmission electron microscopy, and selected area electron diffraction. Hi-Nicalon fiber consists of fine beta-SiC nanocrystals ranging in size from 1 to 30 mn embedded in an amorphous matrix. Sylramic is a polycrystalline stoichiometric silicon carbide fiber consisting of submicron beta-SiC crystallites ranging from 100 to 300 nm. Small amount of TiB2 nanocrystallites (approx. 50 nm) are also present. The LaPO4 coating on Hi-Nicalon fibers consisted of a chain of peanut shape particles having monazite-(La) structure. The coating on Sylramic fibers consisted of two layers. The inner layer was a chain of peanut shape particles having monazite-(La) structure. The outer layer was comprised of much smaller particles with a microcrystalline structure. Bansal, N. P. and Wheeler, D. R. and Chen, Y. L. Glenn Rese
Download or read book Silicon Carbide and Advanced Materials written by Juraj Marek and published by Trans Tech Publications Ltd. This book was released on 2023-05-26 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: Special topic volume with invited peer-reviewed papers only
Download or read book Strength Degrading Mechanisms for CVD SCS 6 SiC Fibers in Argon Environments written by Ramakrishna T. Bhatt and published by . This book was released on 1996 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of Heat Treatment on the Microstructures and Properties of KD I SiC Fibres written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Environmental Effects on the Strength of Sintered Alpha Silicon Carbide written by Ender Savrun and published by . This book was released on 1986 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Treffsicher written by and published by . This book was released on 1995 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
