Damage behavior and mechanism of C/C-SiC composite ablated under different environments

C/C-SiC composite has superior performance and widespread applications while its serving temperature is limited to about 1650 degrees C because of the matrix's active oxidation. In this paper, zirconium silicide was introduced into the matrix of C/C-SiC composite and a matrix modified C/C-SiC composite was produced using Si-Zr-alloyed reactive melt infiltration. Ablation resistance and behavior of the modified composite were evaluated using an oxyacetylene torch in the oxygen-poor and oxygen-rich environments. It was found that the environment had great impact on the ablation resistance of the composites. The composite presented obviously improved ablation resistance in the oxygen-poor environment compared with that in the oxygen-rich environment. A continuous layer of ZrO2 was generated on the composite's ablated surface tested in oxygen-poor environment, acting as a protecting layer to avoid the subsequent severe damage. Conversely, the composite tested in oxygen-rich environment was severely ablated and a deep pit was produced on the ablated surface with a discontinuous layer composed of ZrSiO4, ZrO2, and SiO2 without sufficient protection. The damage mechanism of the composites under different environments was discussed. The damage of the composite tested in the oxygen-poor environment was dominated by the oxidation erosion and evaporation of the SiO2 phase, while the composite's damage tested in the oxygen-rich environment is mainly contributed to the oxidation erosion and blowing away of the liquid ZrO2, ZrSiO4, and SiO2.

Automated summary

By introducing zirconium silicide into the matrix of C/C-SiC composite, the ablation resistance of the composite can be significantly improved. The composite shows improved performance in oxygen-poor environment with a continuous layer of ZrO2 acting as a protective layer, while severe ablation occurs in oxygen-rich environment.