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

Abstract

C/C composites were pre-ablated for different time (0s, 15s, 30s and 45s) under oxyacetylene torch. The mass ablation rate of the C/C composites was 0.39mgcm−2s−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 1873K to room temperature. Compared with the coated C/C composites pre-ablated for 0s, 15s and 45s, 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 30s. 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.