Preparation of β-Phase Silicon Nitride Powders

Abstract

Silicon nitride powders high in β-phase content have been prepared by direct nitriding method. The silicon powders were first milled with 30%α-Si3N4 and 4% FeCl3 for 30 minutes. Then the mixture was heat-treated at 1400°C for 2 hours in the pure nitrogen gas. The phase and the microstructure of the as-prepared product were detected by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results showed that the product mainly consisted of β-Si3N4, whose content is more than 92%, and a little amount of α-Si3N4, and no silicon were detected within the detection limit.