Near Net Shape Preparation of Diamond/SiC Composites

Diamond/SiC composites were near net shaped by Si vapor vacuum reactive infiltration of diamond/C/Si porous preform. Microstructure and properties of the composites were investigated, the influencing factors on the dimensional change of the composites during the reactive infiltration were discussed. The results show that the composites consist of diamond, SiC and a few residual Si. Uniform microstructure and high density (up to 99 %) contribute to high bending strength of 260 MPa. Due to the in-situ reaction between Si and carbon, the preforms expanded with a percentage of 5 %similar to 20 % during the reactive infiltration. With the diamond content, C:Si ratio of the strating materials, and porosity of the preforms increasing, the volume expansibility of the samples decreased. The optimal proportion of Si to C of the starting materials for near net shape preparation of diamond/SiC composites was 1:1.