Fabrication of Si-B-C modified C/C-SiC composite by liquid silicon infiltration

In order to reduce the content of residual Si generated in the process of liquid silicon infiltration, B12(C, Si, B)3 modified C/C-SiC composite was prepared by a joint process of slurry impregnation and liquid silicon infiltration. By analyzing the products of B4C-Si system with different B4C/Si molar ratios after sintered at different temperatures, the formation condition of B12(C, Si, B)3 was studied. The results indicate that B4C starts to react with Si at 1300 °C, leading to the formation of a small amount of B12(C, Si, B)3 and SiC. The amount of B12(C, Si, B)3 generated in the reaction increases with increasing sintering temperature. The sintering product of B4C-Si system with a B4C/Si molar ratio of 3:1 at 1500 °C is composed of B12(C, Si, B)3 and SiC. The C/C-SiC composite fabricated by liquid silicon infiltration is composed of amorphous C, β-SiC and B12(C, Si, B)3, and no residual Si is detected.