MoSi₂-HfC/TaC-HfC multi-phase coatings synthesized by supersonic atmospheric plasma spraying for C/C composites against ablation

To improve the ablation resistance of C/C composites, MoSi₂-HfC/TaC-HfC (MH/TH) bilayer coatings were synthesized on SiC coated C/C composites. Results showed that the mass and linear ablation rate of MH/TH coatings were 0.236 mg/s and 1.026 µm/s, respectively. The excellent performance of MH/TH coatings was attributed to the combination of TH and MH layers. The external TH layer could create Ta₂O₅ and Hf₆Ta₂O₁₇ glassy phase to protect the internal layer and prevent the formation of destructive MoO₃. Meanwhile, the decomposition of the internal MH layer to produce SiO₂ diffusion outward could retard the destruction of the external coating.