Comparison of the ablation resistance of mullite modified C/C-SiC-HfC and C/C-SiC-HfC composites under oxyacetylene flame of 2.38 MW/m2 heat flux

The ablation resistance and ablation mechanism of C/C-SiC-HfC (CSH) and mullite modified C/C-SiC-HfC (MCSH) composites were explored under 30 s x 2 cyclic ablations with oxyacetylene flame at a heat flux of 2.38 MW/m2. The results showed that MCSH exhibits better ablation resistance. During ablation, the introduction of mullite promoted the formation of HfSiO4 and inhibited the consumption of SiO2 and the appearance of porous HfO2. HfSiO4, island-like structures, and flower-like oxide structures were tightly bound on the surface of composites to form a stable and dense Hf-Si-Al-O composite oxide layer, which can effectively resist highvelocity airflow erosion while limiting oxygen diffusion.