SiC whisker-toughened SiC oxidation protective coating for carbon/carbon composites

摘要

Carbon/carbon (C/C) composites are one of the most promising high temperature structural materials for engine, aircraft and aerospace applications, in which C/C composites are required to operate in an oxidizing environment. However, the oxidation of C/C composites at temperatures above 723 K limits their use to inert atmosphere 1,2. Oxidation protective coatings are the logical choice for preventing C/C from oxidation at high temperatures. SiC ceramics are considered as the most suitable coating materials for C/C composites due to their excellent oxidation resistance and good compatibility with C/C substrates 3-6. However, thermal expansion mismatch between SiC and C/C composites will result in the crazing and debonding of SiC coating, and induce the failure of the coatings. According to the toughening mechanism including crack bridging due to whisker pull-out and crack deflection around whiskers 7,8, the toughness of SiC ceramic coatings could be increased by adding SiC whisker (SiCw) in them 9, which will improve the oxidation and thermal stress resistance of SiC ceramic coating.