B₄C-SiC skeleton reinforced graphite composites with excellent mechanical properties

SiC-B₄C ceramic skeleton reinforced graphite composites (MCMB/SiC-B₄C) with extraordinary mechanical performance were fabricated by SPS method. The influence of sintering temperature and volume ratio of B₄C/SiC on the microstructure and mechanical performance of the composites was studied. With the introduction of B₄C in the composites, the B atom diffusion at the B₄C/graphite interface can be activated when the sintering temperature exceeded 1700 °C, which can significantly improve the interfacial combination of the skeleton reinforcement and graphite matrix. Therefore, the relative density and mechanical properties of the composites can be improved. While the sintering temperature reached 1800 °C and the volume ratio of B₄C/SiC was 4:6 (the total amount of ceramic reinforcement phase was 40 vol%), the composite exhibited the optimal comprehensive performance with bending strength of 202 MPa and fracture toughness of 3.29 MPa·m^1/2. These values were 146% and 58% higher, respectively, than those of the composite without B₄C. The developed graphite matrix composites are expected to be applied to extreme conditions such as high load, high temperature and oxidation environments.