Ablation-resistant composite coating of HfC-TaC-SiC for C/C composites deposited by supersonic atmospheric plasma spraying

HfC-TaC-SiC multiphase coating was prepared on the surface of SiC-coated carbon/carbon composites by means of supersonic atmospheric plasma spraying. The morphology and microstructure of the HfC-TaC-SiC coating were characterized with XRD and SEM. The ablation resistance test was performed with an oxyacetylene torch. The results show that the surface of the coating is dense and rough. No crack can be found. The HfC-TaC-SiC coating could protect the substrate from ablation by the generated oxide compound layer. During ablation, the new compound Hf₆Ta₂O₁₇ was generated, which had a single phase and high melting point. In addition, the formed Ta₂O₅ could prevent the phase transition of HfO₂ during the cooling process, which would restrict the volume expansion of HfO₂.