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.