Hot Isostatic Pressing of Synthesized β-Sialon Powders

Highly pure β-sialon powders (z=2 and 3) derived from silicon-diimide were sintered by HIP without additives. The sintering behavior was compared with that of mixed powders of Si3N4, AlN and Al2O3. In synthesized powders, full density was attained after HIPing under 160MPa at 1500°C (z=3) and 1600°C (z=2) for 2h, respectively. These temperatures were found to be 100° to 300°C lower than that required to complete the sialon formation in mixed powders. After HlPing at the lowest temperature necessary for full densification, little grain growth was observed and maximum hardnesses of 16.5GPa (z=2) and 15.0GPa (z=3) were obtained. Fracture toughness was 3 to 4MPa⋅m1/2 by the indentation method. Flexural strength was as low as 250 to 300MPa.