Pressureless sintering of boron carbide

The processing of boron carbide by pressureless sintering with and without additives to obtain dense pellets for use as neutron absorber in fast breeder reactors is reported. The effect of particle size and sintering temperature on density and microstructure was studied. Pressureless sintering of boron carbide powder (0.5 μm) at 2375 °C yielded a pellet of 93% ρth. Addition of zirconium dioxide was found to be beneficial in lowering the sintering temperature. A typical sample with 5 wt% zirconia addition sintered at 2275 °C resulted in a density of 93% ρth and a micro hardness value (HK100) of 32 GPa.