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pyrocarbon matrix composites
690
ABSTRACTS
and addition of graphitized pitch produced the low thermal expansion coefficient characteristic of stress relief without filament failure, and had the highest tensile and shear strengths among several 7-D materials tested. 143. Restrained thermal expansion bebavior of ATJS and some carbon fi~r/py~~n matrix composites* B. L. Butler and J. C. Tidmore (Sanka Laboratories, Albuquerque, New Mexico). The stress generated by restrained thermal expansion of some carbon-carbon composites and ATJ-S has shown that stress relaxation can occur when the material processing temperature is exceeded. The stress relaxation was accompanied by permanent material strain which is indicative of plastic deformation. Thus the thermal response of reentry materials may be time- and temperature-dependent and should be treated accordingly. rfhis work was supported by the United States Atomic Energy ~mmi~ion. 144. Dynamic response of carbon-carbon composites S. Ranganath, Y. P. Gupta and D. H. Petersen (Advanced Technology Center, Inc. Dallas, Texas). Experimental results are presented on the effects of strain rate on the stress-strain behavior under compression of different carbon-carbon composites. These results indicate that the effect of high strain rate is a significant increase in the strength of both conventional phenolic-based and quinone-based matrix system carbon-carbon composites. 145. Processing and properties of pyco-bond/resin char/chopped FORTAFIL fiber composites W. V. Kotlensky, D. W. Bauer (Super-Temp Comjxmy, Santa Fe Springs, Cal@rnia).ljpM. F. Baud and R. PAN-based fiber Prescott (Great L.&es Research Corporation, Elizabethton, Tennessee). Chopped Fortafil mats were fabricated with small amounts of resin binder carbon. Following pyrolysis, the porous mats were densified with pyrolytic carbon. Physical properties of the densified mats were characterized by measurement of flexural, shear and impact strengths along with thermal expansion and thermal conductivity. Pore size distribution was also measured. 146. Properties aud application of Mod-3 pierced fabric reinforced carbon/carbon composites P. G. Rolincik (AVCO Corporation, SystemsDivision, Lowell, ~~sach~e~). Carbon/carbons have emerged for application as reentry nose tips, re-entry cassettes, leading edges, aircraft brakes and rocket nozzles. One leading carbon/carbon is called MOD-3, which is formed by piercing layers of graphite fabric with high strength graphite fibers, followed by carbon matrix processing. MOD-3, as compared with a leading ~Iy~ystaI~ne graphite ATJS, has higher strength, less flaw sensitivity and enhanced thermal stress resistance, while maintaining a low thermo-mechanical erosion rate and a high sublimation energy. Finally, MOD-3 can be fabricated reproducibly in various sizes and shapes. 147. Development of structure in ~lya~lo~~le-~~ fibers J. S. Perkins, D. B. Barr and 0. A. King (Amay Materials and MechaGctr Research Center, Watertown, Massachusetts). Fibrils which are structural elements of carbon fibers are found at all stages of pyrolysis starting with the untreated polyacrylonitrile (PAN) fiber. Evidence based on simultaneous chemical reactions will be presented to account for liquid phase migration, layers of macro and micro voids, conversion from radial to ~rcumferential orientation as modulus increases, and the origin of i-ibbons’. 148. Pyrolytic analysis of carbon fibers J. S. Perkins (Amy Materials and Mechanics Research Center, Watertown, Massachusetts), D. S. Smith and D. Rivin (Cabot crates, silica, M~sa~h~et~). A sensitive thermal analytical method originally developed for determining the surface group distribution on carbon blacks has been successfully used to characterize carbon fibers. Even a graphitized fiber, with only a small fraction of the surface active, yields information on the types and amounts of functionalities present. Pyrolysis volatile analysis (PVA) is also effective for evaluating surface activating methods.
ABSTRACTS
and addition of graphitized pitch produced the low thermal expansion coefficient characteristic of stress relief without filament failure, and had the highest tensile and shear strengths among several 7-D materials tested. 143. Restrained thermal expansion bebavior of ATJS and some carbon fi~r/py~~n matrix composites* B. L. Butler and J. C. Tidmore (Sanka Laboratories, Albuquerque, New Mexico). The stress generated by restrained thermal expansion of some carbon-carbon composites and ATJ-S has shown that stress relaxation can occur when the material processing temperature is exceeded. The stress relaxation was accompanied by permanent material strain which is indicative of plastic deformation. Thus the thermal response of reentry materials may be time- and temperature-dependent and should be treated accordingly. rfhis work was supported by the United States Atomic Energy ~mmi~ion. 144. Dynamic response of carbon-carbon composites S. Ranganath, Y. P. Gupta and D. H. Petersen (Advanced Technology Center, Inc. Dallas, Texas). Experimental results are presented on the effects of strain rate on the stress-strain behavior under compression of different carbon-carbon composites. These results indicate that the effect of high strain rate is a significant increase in the strength of both conventional phenolic-based and quinone-based matrix system carbon-carbon composites. 145. Processing and properties of pyco-bond/resin char/chopped FORTAFIL fiber composites W. V. Kotlensky, D. W. Bauer (Super-Temp Comjxmy, Santa Fe Springs, Cal@rnia).ljpM. F. Baud and R. PAN-based fiber Prescott (Great L.&es Research Corporation, Elizabethton, Tennessee). Chopped Fortafil mats were fabricated with small amounts of resin binder carbon. Following pyrolysis, the porous mats were densified with pyrolytic carbon. Physical properties of the densified mats were characterized by measurement of flexural, shear and impact strengths along with thermal expansion and thermal conductivity. Pore size distribution was also measured. 146. Properties aud application of Mod-3 pierced fabric reinforced carbon/carbon composites P. G. Rolincik (AVCO Corporation, SystemsDivision, Lowell, ~~sach~e~). Carbon/carbons have emerged for application as reentry nose tips, re-entry cassettes, leading edges, aircraft brakes and rocket nozzles. One leading carbon/carbon is called MOD-3, which is formed by piercing layers of graphite fabric with high strength graphite fibers, followed by carbon matrix processing. MOD-3, as compared with a leading ~Iy~ystaI~ne graphite ATJS, has higher strength, less flaw sensitivity and enhanced thermal stress resistance, while maintaining a low thermo-mechanical erosion rate and a high sublimation energy. Finally, MOD-3 can be fabricated reproducibly in various sizes and shapes. 147. Development of structure in ~lya~lo~~le-~~ fibers J. S. Perkins, D. B. Barr and 0. A. King (Amay Materials and MechaGctr Research Center, Watertown, Massachusetts). Fibrils which are structural elements of carbon fibers are found at all stages of pyrolysis starting with the untreated polyacrylonitrile (PAN) fiber. Evidence based on simultaneous chemical reactions will be presented to account for liquid phase migration, layers of macro and micro voids, conversion from radial to ~rcumferential orientation as modulus increases, and the origin of i-ibbons’. 148. Pyrolytic analysis of carbon fibers J. S. Perkins (Amy Materials and Mechanics Research Center, Watertown, Massachusetts), D. S. Smith and D. Rivin (Cabot crates, silica, M~sa~h~et~). A sensitive thermal analytical method originally developed for determining the surface group distribution on carbon blacks has been successfully used to characterize carbon fibers. Even a graphitized fiber, with only a small fraction of the surface active, yields information on the types and amounts of functionalities present. Pyrolysis volatile analysis (PVA) is also effective for evaluating surface activating methods.