In situ synthesis of ZrB ₂ –ZrC–SiC ultra-high-temperature nanocomposites by a sol–gel process

ZrB2–ZrC–SiC is one of the ultra-high-temperature ceramic composites with excellent properties. In this research, high-purity ZrB2–ZrC–SiC nanopowders were synthesised using a carbothermal reduction reaction at a relatively low temperature (1370°C) from cost-effective zirconium(IV) chloride by a sol–gel method. The effect of heat treatment temperature on the synthesis of ZrB2–ZrC–SiC composite powder was studied. X-ray diffractometry results showed that the phases ZrB2, β-SiC and ZrC were synthesised at 1370°C. The mean crystallite sizes for each of the phases were calculated using the Scherrer method. The specific surface area for the sample calcined at 1370°C was 81.479 m2 g−1. SEM observation revealed that the particles had a size lower than 250 nm. Backscattered electron image and map analysis with scanning electron microscopy showed that a suitable phase homogeneity was achieved, as confirmed by energy-dispersive X-ray spectroscopy.