The effect of sol-gel process on the microstructure and particle size of ZrC–SiC composite powders

Abstract

ZrC–SiC composite powders were successfully synthesized by the combination of sol-gel technology and carbothermal reduction. The characterization of these powders was conducted by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effects of the important parameters of sol-gel process including the desiccant method, timing of introducing carbon source and heating-drying temperature on the final ZrC–SiC particle size and its distribution range were studied in details, and the mechanism of ZrC–SiC particles agglomeration and coalescence was also explored. The results show that the mean particle size increases with the heating-drying temperature rising, but introducing carbon source before gelation together with a freeze-drying treatment can produce the ultrafine ZrC–SiC composite powders having a minimum particle median diameter of 0.174 μm and the narrowest size distribution range.