Effect of Al addition on pressureless sintering of B4C

The effect of Al additions on the pressureless sintering of B4C ceramics was investigated. Different amounts of Al, from 0 to 5 wt% were added to the base material and pressureless sintering was conducted at 2050 and 2150 C under an argon atmosphere. Microstructure, crystal phases and density evolution were studied and correlated with Al additions and firing temperature. Density and grain size of the sintered samples, increased significantly with the Al loading while less evident was the effect of sintering temperature. 94% dense material was obtained by adding 4 wt% Al regardless of the maximum firing temperature.