Microstructure and ablation behavior of SiC coated C/C-SiC-ZrC composites prepared by a hybrid infiltration process

In this study, C/C-SiC-ZrC composites coated with SiC were prepared by precursor infiltration pyrolysis combined with reactive melt infiltration. The pyrolysis behavior of the hybrid precursor was investigated using thermal gravimetric analysis-differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy techniques. The microstructure and ablation behavior of the composites were also investigated. The results indicate that the composites exhibit an interesting structure, wherein a ceramic coating composed of SiC and a small quantity of ZrC covers the exterior of the composites, and the SiC-ZrC hybrid ceramics are partially embedded in the matrix pores and distributed around the carbon fibers as well. The composites exhibit good ablation resistance with a surface temperature of over 2300 °C during ablation. After ablation for 120 s, the mass and linear ablation rates of the composites are 0.0026 g/s and 0.0037 mm/s, respectively. The great ablation resistance of the composites is attributed to the formation of a continuous phase of molten SiO2 containing SiC and ZrO2, which seals the pores of the composites during ablation.