Ablation behaviours of C/C-ZrC-SiC-mullite composites with varying mullite content under high-temperature oxidizing gas flow

The mullite modified C/C-ZrC-SiC composites with different content of mullite were prepared by PIP and subjected to 50 s × 3 cyclic ablation. The results demonstrate that moderate mullite content is conducive to enhanced cyclic ablation behavior in C/C-ZrC-SiC. The oxidation of ZrC and SiC occurs concurrently with the decomposition of mullite, further forming a Zr-Al-Si-O multiphase oxide layer . The dense Zr-Si-Al-O multi-phase oxide layer has the ability to resist the scouring of airflow and inhibit the diffusion of oxygen into the substrate, thus providing superior protection for the substrate during cyclic ablation. • The mullite modified C/C-ZrC-SiC composites were prepared by precursor infiltration and pyrolysis. • The results show that the composites with 9 wt. % mullite content exhibits excellent ablation performance. • Mullite decomposes into SiO 2 and Al 2 O 3 , which play crucial roles in maintaining the intact structure of the oxide layer. • The dense Zr-Si-Al-O multiphase oxide layer significantly resists gas scouring and inhibits oxygen diffusion.