Effect of MgCl2 addition on the preparation of ZrC-SiC composite particles by sol-gel

In the present study, an efficient sol-gel process combined with carbothermal reduction was designed to directly synthesize high purity hybrid ZrC-SiC powders by adding MgCl2 at a lowered temperature. The composition and morphology evolution of the final products were studied in detail. The fabrication conditions of the ZrC-SiC powders, such as the amount of MgCl2, heat-treating temperature and soaking time, were optimized. Experimental results revealed that the addition of MgCl2 could dramatically accelerate the formation of low carbonresidual ZrC-SiC powders even at 1400 degrees C, which is lower than the typical synthesis temperature of about 1600 degrees C. Thereinto, the ZrSiO4 transition phase, which appeared after MgCl2 addition, plays a vital role in reducing the carbothermal reduction temperature. Moreover, a stoichiometric carbon in the hybrid ZrC-SiC powders was realized by controlling MgCl2 addition.