The effect of Fe addition on the densification of B ₄C powder by spark plasma sintering

Boron carbide is a low-density ceramic with high hardness and stiffness values that make it a valuable candidate for light armor applications. Fully dense boron carbide is fabricated by hot pressing of fine (<2 μm) powder at a relatively high temperature (2150-2200°C). Fully dense boron carbide can be processed from an initial mixture of 5.5 vol.% Fe and low-cost B ₄C powder by spark plasma sintering (SPS) at 2000°C. At this temperature, Fe-free boron carbide can be consolidated only to 96% of the theoretical density. The effect of the Fe addition on the densities is even more pronounced at lower processing temperatures and is related to the presence of a liquid phase in the Fe-containing material. The resulting microstructure and mechanical properties of the Fe-containing boron carbide are presented and discussed.