Structure and properties of MoSi2–MeB2–SiC (Me = Zr, Hf) ceramics produced by combination of SHS and HP techniques

Composites MoSi2–ZrB2–SiC and MoSi2–HfB2–SiC were investigated in this study as the prospective materials for high-temperature industrial heaters. The composites with relative density 97–98% were produced by combustion synthesis followed by hot pressing. The macrokinetic features of combustion, as well as phase and structure formation mechanisms in the combustion waves, were analyzed and their influence on the structure, mechanical properties, and performance of heaters were ascertained. The mechanical and electrical properties of the heating elements produced in this work are considerably higher as compared to conventional MoSi2 counterparts. Among the investigated compositions, the MoSi2–HfB2–SiC demonstrated the highest resistance to high-temperature oxidation. Both compositions featured the formation of a stable continuous oxide layer consisting of crystalline α-quartz (high-temperature modification of SiO2) reinforced by ZrO2, ZrSiO4, HfO2, and HfSiO4 precipitates.