Improved ablation resistance of C_sf/SiBCN composites densified by PIP process: Ablation behavior and damage mechanism

To enhance the ablation resistance of porous C_sf/MA–SiBCN composites, the polymer infiltration and pyrolysis (PIP) process is adopted to obtain layered C_sf/SiBCN composites containing MA–SiBCN and PDCs–SiBCN. After ablation for 10 s, the ablative layer fails to remain on the C_sf/MA–SiBCN surface with mass ablation rate of 0.062 g/s and linear ablation rate of 0.208 mm/s, while the dense C_sf/SiBCN surface is covered by a dense and stable ablative layer mainly consisting of amorphous SiO₂ glassy phase due to the synergistic ablation effect of MA–SiBCN and PDCs–SiBCN, which could resist the intense scour by ablation flame and prevent internal corrosion, and thus the ablation resistance improves with a 37% decrease in mass ablation rate (0.039 g/s) and an 18% decrease in linear ablation rate (0.171 mm/s), respectively.