Preparation and Properties of B4C-SiC Composite Ceramics

Pure B4C and B4C-20%SiC composite ceramics were prepared by hot-pressing sintering technique after ball-mill mixing in the temperature range of 1 900-2 100 ℃,using B4C powder with a particle of 10.22 μm and β-SiC powder of 1.07 μm as the starting materials.Phase structure and mechanical properties had been studied.The results indicate that,SiC addition had little effect on the densification of B4C composites,and the relative densities of pure B4C ceramic and B4C-20%SiC composite were 87.9% and 87.0% respectively at the sintering temperature of 2 100 ℃.Porosity influenced the mechanical properties of B4C based composites greatly,and the relationship between bending strength (σw) and porosity (θ) could be expressed as σw=257exp(-2.18θ).