Sol-gel derived silicon nitride powders

The sol-gel synthesis of silicon nitride powders has been studied. The precursor gels were prepared from a colloidal dispersion of silicon dioxide and sucrose, with mole ratios of reactants, C/SiO2, ranging from 2 to 4. The carboreduction and nitridation processes were performed at temperatures between 1400-1550 degrees C under a dynamic nitrogen atmosphere, with a 4 h hold. The optimum C/SiO2 ratio and temperature for preparation of the Si3N4 powders were selected. For the SiO2-C-N-2 system examined, the boundary temperature between Si3N4 and SiC formation was established, in relation to the amount of carbon introduced.