Processing and properties of silicon carbide and its composites containing MoSi2 and ZrB2

Near theoretical density SiC and its composites SiC–30 vol% MoSi2 and SiC–30 vol% ZrB2 were prepared through hot pressing under vacuum using commercial purity powders with Y2O3 and AlN as sintering additives. These materials were characterized for constituent phases and microstructure using XRD, SEM/EDS, and TEM/EDS techniques. The composites showed a reduction in flexural strength and improvement in fracture toughness as compared to SiC. The distribution of the second phase in SiC matrix was such that its resistivity decreased from 2.6 MΩ cm to 280 μΩ cm. The second phase particles were also found to reduce the room temperature thermal conductivity of SiC.