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 degrees C, and the effect of heat treatment at 1400 degrees C for 10, 20, or 30 h on the microstructure and ablation properties of the composites fabricated using three different ternary alloys (e.g., Zr0.047B0.0378Si0.9152, Zr0.0724B0.0366Si0.891, and Zr0.1B0.05Si0.85) 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 Zr0.0724B0.0366Si0.891 demonstrated the best ablation performance. Their linear and mass ablation rates at 1911 degrees C were -0.11 mu m s(-1) and 1.82 mu g s(-1), respectively.