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Oxidation of Carbon Fiber‐Reinforced Silicon Carbide Matrix Composites at Reduced Oxygen Partial Pressures
Author(s) -
Opila Elizabeth J.,
Serra Jessica L.
Publication year - 2011
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.1551-2916.2010.04376.x
Subject(s) - materials science , oxygen , silicon carbide , composite material , partial pressure , fiber , polyacrylonitrile , thermogravimetric analysis , carbon fibers , kinetics , silicon , chemical engineering , chemistry , metallurgy , composite number , polymer , organic chemistry , quantum mechanics , engineering , physics
Carbon fibers (Polyacrylonitrile‐derived T‐300) and T‐300 carbon fiber‐reinforced silicon carbide composites (C/SiC) were oxidized in flowing 0.1 MPa reduced oxygen partial pressure environments (50% O 2 , 5% O 2 , 0.5% O 2 , and 0.1% O 2 in argon). Experiments were conducted at temperatures of 816°, 1149°, 1343°, and 1538°C. The oxidation kinetics were monitored using thermogravimetric analysis. T‐300 fibers were completely oxidized for times between 0.6 and 325 h. C/SiC coupons were oxidized for either 25 or 100 h. Fiber oxidation rates had an oxygen partial pressure dependence with a power‐law exponent close to one but were only weakly dependent on temperature. Fiber oxidation kinetics were consistent with gas‐phase diffusion control at these temperatures. The C/SiC coupon oxidation kinetics showed some variability, attributed to differences in the number and width of cracks in the SiC seal coat. Oxidation of the carbon fibers dominated the coupon oxidation behavior. For C/SiC coupons, low temperatures and high oxygen pressures resulted in the most rapid consumption of the carbon fibers. At higher temperatures, the lower oxidation rates were attributed to crack closure due to SiC thermal expansion, rather than oxidation of SiC. At the highest temperature and lowest oxygen partial pressure, active oxidation of SiC was observed.