Effects of high-temperature annealing on the microstructure and properties of C/ZrC composites prepared by reactive melt infiltration

C/ZrC composites prepared by reactive melt infiltration at 1900 degrees C contained similar to 4.2 vol% residual alpha-Zr which was harmful to the high-temperature mechanical properties and ablation resistance. Thus, the composites were heat-treated for 1 h from 1200 degrees C to 2000 degrees C. The residual a-Zr amount was only 0.6 vol% after annealing at 2000 degrees C, indicating that high temperature promoted the diffusion and reaction of Zr and C to consume alpha-Zr. C/ZrC composites had the optimum flexural properties of 192 MPa and 17.7 GPa after annealing at 1600 degrees C. The ablation resistance was improved after high-temperature annealing, and the mass loss rate and linear recession rate decreased as the temperature increased, which were 0.0021 g/s and 0.0008 mm/s respectively after annealing at 2000 degrees C.