Influence of diamond graphitization on the microstructure and performance of micro-diamond modified C/C composites

Micro-diamond modified C/C composites (C/C-D composites) were fabricated using pressureless infiltration (PI) and chemical vapor infiltration (CVI) methods. And the influence of diamond graphitization on the microstructure and performance of C/C-D composites were investigated. During further graphitization process of diamond particles (1600 degrees C), thicker graphite layer formed on diamond surface accompanied by volume expansion, which induced stress graphitization to surrounding PyC. Meanwhile, the graphite/PyC interface bonding strength improved significantly after diamond graphitization. Compared with the low strength retention rate of C/C composites (46.8%) after heat treated at 1600 degrees C, a high strength retention rate was achieved for C/C-D composites (87.1%) benefiting from the enhanced graphite/PyC interface bonding strength after diamond graphitization. And the thermal conductivity of the as-prepared C/C-D composites increased by 32.5% with the addition of diamond particles (9.97 wt%). It could be expected that C/C composites with optimal microstructure and excellent performances can be obtained by adjusting the content and graphitization degree of diamond particles in future work.