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.