Effect of SiC addition on the formation of ZrB2 through reaction of ZrO2, boric acid (H3BO3) and carbon black

ZrB2-SiC powders with different amounts of SiC (10-30 wt%) were in-situ synthesized at 1600 °C for 90 min in Ar atmosphere. Effects of SiC addition on the formation of ZrB2 via carbothermal reduction of ZrO2, H3BO3 and carbon black were investigated. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and transmission electron microscope (TEM). The grain size of ZrB2 in final powders decreased with adding SiC. Columnar ZrB2 and granular SiC were combined interactively when the SiC content was 25 wt%. Layer-like hexagonal SiC was obtained in the product containing 30 wt% SiC, whereas the ZrB2 grain growth was strongly inhibited. Furthermore, the growth mechanisms of ZrB2 and SiC were studied.