The ablation behavior of mullite modified C/C-SiC-ZrC composites under oxyacetylene flame at a heat flux of 4.18 MW/m² with different mullite content

Mullite modified C/C-SiC-ZrC composites were fabricated by precursor infiltration and pyrolysis (PIP), and the composites underwent oxyacetylene ablation at a flow rate of 4.18 MW/m². The influence of different mullite concentrations on the microstructure and ablation properties of the composites was investigated. The results showed that both high and low mullite contents had negative impacts on the ablation resistance of the composites. At a mass fraction of 12 wt% of mullite in the precursor solution, the composites were fabricated with linear and mass ablation rates of 3.77 μm/s and 2.63 mg/s, respectively, which achieved the optimum ablation resistance. A moderate amount of mullite could act as a sufficient liquid phase healing agent at high temperature. It formed a dense Zr-Si-Al-O multiphase oxide layer. This oxide layer effectively retarded the scouring by high velocity airflow and protected the composites from high temperature erosion.