Preparation of Si3N4 Form Diatomite via a Carbothermal Reduction-Nitridation Process

Abstract

Si3N4 was produced using diatomite and sucrose as silicon and carbon sources, respectively. The effect of the C/SiO2 molar ratio, heating temperature and soaking time on the morphology and phase compositions of the final products was investigated by scanning electron microscopy, x-ray diffraction analysis and energy dispersive spectroscopy. The phase equilibrium relationships of the system at different heating temperatures were also investigated based on the thermodynamic analysis. The results indicate that the phase compositions depended on the C/SiO2 molar ratio, heating temperature and soaking time. Fabrication of Si3N4 from the precursor via carbothermal reduction nitridation was achieved at 1550°C for 1–8 h using a C/SiO2 molar ratio of 3.0. The as-prepared Si3N4 contained a low amount of Fe3Si (<1 wt.%).