PRESSURELESS SINTERING OF SiC-B_4C COMPOSITES

摘要

Two desirable properties for armour ceramics are a high hardness and a low density. It is therefore no surprise that both silicon carbide and boron carbide are lead ceramics for ballistic protection. However removing porosity during sintering is difficult and often hot pressing is required. Compared to pressureless sintering this is more costly and more limiting in terms of the shapes that can be produced. Therefore this paper describes experiments carried out to explore the potential for pressureless sintering of composites of boron carbide and silicon carbide. Mixtures of pure powders across the entire compositional range as well as mixtures with a range of sintering additives were pressureless sintered at temperatures up to 2300 °C. It is found that addition of 3 wt% carbon enables high densities to be obtained across the entire compositional range. The hardness is only weakly dependent on composition varying between 29.3 and 33.3 GPa.