Structural evolution and ablation mechanism of a hafnium carbide coating on a C/C composite in an oxyacetylene torch environment

摘要

HfC coating was deposited on carbon/carbon composites by chemical vapor deposition. The evolution of morphology and microstructure of the coating during ablation is investigated and the ablation mechanism is proposed. Results show that the coating shows an outstanding ablation resistance. After ablation, three distinct regions (central, transitional and outer ablation region) can be detected on the coating surface. In the former two regions, four layers can be divided from the cross-section of the ablated coating. Both molten HfO_2 and HfC_xO_y could act as oxygen diffusion barrier during ablation. Oxidation and mechanical erosion are main ablation behavior of the HfC coating.