Effect of heat treatment on the microstructure and ablation performance of C/C-SiC composites containing ZrSi₂-Si

Low-temperature reactive melt infiltration (LRMI) is advantageous for the fabrication of ceramic matrix composites (CMCs). However, residual metal in CMCs prepared by LRMI deteriorates the high-temperature properties. In this study, C/C-SiC composites containing ZrSi₂-Si were prepared using LRMI at 1400 °C, and the effect of heat treatment at 1400 °C for 10, 20, or 30 h on the microstructure and ablation properties of the composites fabricated using three different ternary alloys (e.g., Zr_0.047B_0.0378Si_0.9152, Zr_0.0724B_0.0366Si_0.891, and Zr_0.1B_0.05Si_0.85) was investigated. The results show that the residual Si in the composites can be decreased by volatilisation and the reaction between Si and C during heat treatment, resulting in a decrease in the density and an increase in the SiC content. The ablation rates of the composites after heat treatment for 20 h were lower than those of the samples after heat treatment for 30 and 10 h. Among the three alloys, the composites prepared using Zr_0.0724B_0.0366Si_0.891 demonstrated the best ablation performance. Their linear and mass ablation rates at 1911 °C were -0.11 μm s^-1 and 1.82 μg s^-1, respectively.