Improved oxidation and thermal shock resistance of SiC-Si coating with a SiCw/PyC network structure toughened buffer layer

Abstract

To improve the anti-oxidation property of carbon/carbon (C/C) composites, a SiC-Si coating with a buffer layer toughened by SiC whisker/pyrolytic carbon (SiCw/PyC) core-shell network (SSwP) was prepared. Static oxidation resistance and thermal shock behavior of the coating were investigated. The weight loss of the SSwP-coated sample decreased by 77.5 % compared with the SiC-Si coating after 12 thermal cycles between room temperature and 1773 K, and was 0.39 % after 20 thermal cycles. The improved coating stability in thermal cycling was attributed to whisker branching and pull-out. After 300 h oxidation at 1773 K, the weight loss decreased by 28.99 % compared with the SiC-Si coating. The buffer layer promoted crack deflection and alleviated thermal stress. Therefore, the resistance of penetrating crack was enhanced, and the anti-oxidation performance was improved eventually.