MoSi2 modified HfC coating for the ablation protection of SiC-coated C/C composites: Ablation resistance and behavior.

To improve the ablation resistance of HfC coating, HfC-MoSi 2 coatings with different MoSi 2 content were prepared on SiC-coated carbon/carbon (C/C) composites by supersonic atmospheric plasma spraying (SAPS). The effects of MoSi 2 content on the microstructure, phase composition and ablation behavior of HfC-MoSi 2 coating were investigated. The ablation resistance of as-prepared coatings was tested under the oxyacetylene flame with a heat flux of 2.4 MW/m2. The results showed that the HfC-(25 vol%) MoSi 2 coating exhibited better ablation resistance, and its mass and linear ablation rate are 0.23 mg/s and 0.48 µm/s, respectively. Such good performance was ascribed to the formation of Hf-Si-O compound phases, which effectively filled the diffusion channel of oxygen and improved the compactness of the coating. • In present study, the ablation resistance and behavior of the HfC-MoSi 2 multiphase coatings were researched in detail. • Compared other HfC multiphase coatings, MoSi 2 was helpful to form Hf-Si-O phases, inhibiting the permeation of oxidizing gas. • The ablation behavior of HfC-MoSi 2 coatings was analyzed and HfC-25vol%MoSi 2 coating showed the best ablation resistance. [ABSTRACT FROM AUTHOR]