Pre-ablation treatment of carbon/carbon composites to improve the thermal shock resistance for SiC coating under oxyacetylene torch

C/C composites were pre-ablated for different time (0 s, 15 s, 30 s and 45 s) under oxyacetylene torch. The mass ablation rate of the C/C composites was 0.39 mg cm ^-2 s ^-1 . An interlocking transition layer of SiC was formed on the pre-ablated C/C composites by pack cementation. Thermal shock test of the SiC coated C/C composites was performed under oxyacetylene torch from 1873 K to room temperature. Compared with the coated C/C composites pre-ablated for 0 s, 15 s and 45 s, after 10 thermal cycles, no coating/substrate gaps or penetrating cracks were found in the SiC coated C/C composites with the C/C substrate pre-ablated for 30 s. The good shock performance was attributed to the interlocking structure of transition layer, which could efficiently alleviate the mismatch of thermal expansion coefficient between C/C substrate and SiC coating.