Ablation behavior of Y₂O₃ modified HfC-based coatings for carbon/carbon composites above 2200°C

To improve the ablation resistance of C/C composites, Y₂O₃ with different contents modified HfC-MoSi₂ multi-phase coating was prepared by supersonic atmospheric plasma spraying. The microstructural and phase compositional evolution of as-prepared coating was studied both before and after ablation. The effect of Y₂O₃ content on the ablation resistance and behavior of the coating was investigated in detail. The results showed that the incorporation of Y₂O₃ enhances the high-temperature stability of SiO₂ oxide films and suppresses their volatilization at elevated temperatures. Furthermore, the formation of Y₂Hf₂O₇ and Y₂Si₂O₇ through the reaction between Y₂O₃, HfO₂ and SiO₂ promotes the development of a compact oxide scale, effectively inhibiting gas diffusion into the interior of the coating. Consequently, these improvements contribute to enhanced ablation resistance of the coating.