MECHANISM OF THE CARBOTHERMAL SYNTHESIS OF MgAl_2O_4-SiC REFRACTORY COMPOSITE POWDERS BY FORSTERITE, ALUMINA AND CARBON BLACK

摘要

and SiC play an important role in the carbon-containing refractory. In this paper, refractory composite powders were prepared by using forsterite, alumina and carbon black by carbothermal reaction. The effects of the calcined temperature and the proportion of carbon black on phase composition and microstructure of MgAl_2O_4-SiC powders were investigated. The mechanism of synthesis processing was discussed. The result shows that MgAl_2O_4 crystallite formed by solid phase reaction, most like the reaction of the forsterite and alumina, and its growth occurred by solid-liquid phase reaction. The silicon carbide was synthetized using the vapour-liquid-solid mechanism in a FeSi droplet.