Effect of tantalum carbide on the ablation behaviors of hafnium carbide coating for C/C composites under single and cyclic oxyacetylene torch environments

A HfC-TaC/SiC multilayer coating was synthesized on carbon/carbon (C/C) composites by supersonic atmospheric plasma spray (SAPS) and pack cementation (PC) methods. Ablation performance of the coating was characterized under single and cyclic oxyacetylene torch with a heat flux of 4.18 MW/m², and the phase composition and morphology of the oxide layer were surveyed systematically. During single ablation, a continuous Hf-Ta-O compound scale was formed on the surface, which is responsible for the better ablation performance of HfC-TaC coating compared with monophasic HfC coating. As for cyclic ablation, ablation crater appears on both HfC and HfC-TaC coating surfaces due to the multiple thermal shocks, but the size of the latter is reduced significantly.