Thermal damage and microstructure evolution mechanisms of Cf/SiBCN composites during plasma ablation

Ablation behavior and thermal damage mechanisms of C-f/SiBCN composites were investigated in plasma ablation flame under a heat flux of 4.02 MW/m(2), simulating a hypersonic service environment at similar to 2200 degrees C. Oxide layer formed on the composites surface effectively protects internal C-f/SiBCN composites from further ablation. However, the internal C-f/SiBCN composites endure severe thermal damage and complex reactions, leading to decomposition of SiBCN matrix and formation of alpha/beta-SiC, beta-Si3N4 grains, amorphous C layer and ring-like SiC layer. Based on detailed microstructure and phase composition analysis, thermal damage and microstructure evolution mechanisms of C-f/SiBCN composites during plasma ablation are clarified.