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

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 pm and the narrowest size distribution range.