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Effect of Firing Temperature on the Thermal Stability of Low‐Oxygen Silicon Carbide Fibers
Author(s) -
Shimoo Toshio,
Tsukada Ichiro,
Seguchi Tadao,
Okamura Kiyohito
Publication year - 1998
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1998.tb02593.x
Subject(s) - materials science , composite material , silicon carbide , ultimate tensile strength , fiber , crystallinity , electrical resistivity and conductivity , oxygen , thermal stability , chemical engineering , chemistry , organic chemistry , electrical engineering , engineering
Low‐oxygen SiC fibers which were fabricated by curing with electron‐beam irradiation and firing at 1273 and 1573 K (fiber‐A and fiber‐B) were exposed at 1673 to 1973 K. Significant differences in surface composition, crystallinity, specific resistivity, and tensile strength were found between fiber‐A and fiber‐B. On exposing the fibers to high temperatures, they both crystallized nearly completely into intermixed β‐SiC and free carbon, and consequently the resistivity decreased markedly. Deep voids were formed at the surface of fiber‐A as a result of rapid dehydrogenation at the earliest stage of high‐temperature exposure. On the other hand, fiber‐B, which decomposed mildly, had a dense pore‐free structure. The fiber strength was proportional to the reciprocal square root of SiC crystal size. At the same crystal size, the strength of fiber‐A was lower because of the surface flaws.