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 × 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 high-velocity airflow erosion while limiting oxygen diffusion.