Spark plasma sintering of ultra refractory compounds

Spark plasma sintering experiments were conducted on Zr- and Hf-based borides and carbides with the addition of 1, 3, and 9 vol% MoSi₂ as sintering aid. For comparison, as-received ZrC, HfC, ZrB₂, HfB₂ powders were also sintered. The microstructural features were investigated by means of scanning electron microscop–energy dispersive spectroscopy technique. Silicon carbide was detected in all the doped compositions along with significant amounts of oxide species (Hf/ZrO₂, and SiO₂). The effect of the MoSi₂ content on densification, microstructure, and mechanical properties is analyzed.