Synthesis of Si3N4 by the carbo-thermal reduction and nitridation of diatomite

A study was undertaken to production of Si3N4 powders by carbo-thermal reduction and nitridation (CTRN) of diatomite. Test samples were prepared by mixing 99% purity and mean powder size of 2.4 μm of carbon black and maximum particle size of 150 μm diatomite with C/SiO2 molar ratio 4. Prepared sample was subjected to CTRN process at temperatures of 1300, 1350, 1400, and 1450 °C for 4, 8, and 16 h. CTRN process was conducted in an atmosphere controlled tube furnace in nitrogen flow 5 cm3/min. All products were examined by XRD and SEM-EDX to determine the transformation, morphology and chemical composition. The results showed that the best Si3N4 transformation occurred at 1400 °C for 16 h.