Effect of the addition of silicon nitride on sintering behaviour and microstructure of zirconium diboride

Using Si3N4 as a sintering aid in ZrB2 greatly improved densification and microstructure compared to additive-free zirconium diboride. Nearly fully dense material was obtained by hot pressing at 1700 C. The microstructure consists of fine ZrB2 grains and of grain boundary phases (BN, ZrO2, ZrSi2, B-N-O-Si-Zr glassy phase) mainly located at triple points.