An inlaid interface of carbon/carbon composites to enhance the thermal shock resistance of SiC coating in combustion environment

Abstract

Abstract To relieve the mismatch of thermal expansion coefficient and enhance the service reliability of SiC coating efficiently, blasting treatment of C/C composites conducted by oxyacetylene torch, as a surface modification method, was used. SiC coating was prepared on the treated C/C composites by pack cementation, and an inlaid interface with different structures between SiC coating and C/C substrate was achieved. High temperature test was conducted under oxyacetylene torch, and the oxyacetylene flame was parallel to the as-received SiC coated C/C composites. After 5 thermal cycles from 1750 °C to room temperature, a glassy SiO2 protective layer without macro-crack was formed on the surface of the coated C/C composites with pre-blasting treatment in the heat flux of 3.2 MW/m2. The good thermal cycle performance was attributed to the inlaid interface, which could relieve the thermal stress, improve the bonding strength and alleviate the mismatch of thermal expansion coefficient between C/C substrate and SiC coating efficiently.