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.