Calculated influences of starting materials composition on carbothermal nitridation synthesis of silicon nitride/silicon carbide composite powders

Equilibrium phase composition at 1 atm total pressure is quantitatively cal culated as the function of starting materials composition for carbothermal nitridation synthesis of Si3N4/SiC composite powders. N-2 flow is simulated by the N-2 amount in the starting materials. At low starting N-2 content ( molar ratio N-2/SiO2 less than or equal to 100), Si3N4 and SiC can not exis t in equilibrium at the same temperature. At higher starting N-2 content, t he Si3N4-SiC coexisting temperature range appears above 1760 K. The upper l imit of the temperature range becomes higher with increasing starting N-2 c ontent. Starting carbon content affects the composition in the equilibrium powder products. The calculation results are compared with experiments. (C) 2001 Kluwer Academic Publishers.