Silicon Nitride Nano-Ceramics from Mechanically Ground Powder

Abstract

Fine silicon nitride powder was prepared by mechanical grinding. Commercial submicrometer powder with sintering additives was ground with aluminium metal. Peaks of silicon nitride broadened after grinding in XRD analysis. This suggested that particle size of silicon nitride decreased. The powder was hot-pressed in nitrogen at 30MPa for 5 minutes. Heating rate was about 300 K/min to prevent grain growth. Dense material was obtained by sintering at 1550 ^oC. Crystalline phases of the material were silicon nitride and sialon. Fractured surface was observed by SEM. Fine grains of 100-200 nm were observed.