Sintering and properties of beta-'-sialon with a nitrogen-rich Y2O3 sintering aid

The synthesis of dense sintered sialon with external additives selected from the system Y2O3–AIN–SiO2 is reported. The highest density (3.21 g/cm3) was achieved at 1750°C at 90 min of sintering with 5 wt% additive. The degree of sialon substitution increased with the amount of liquid; the YSiO2N crystalline phase formed concurrently. Strength degradation occurred above 1000°C. The fracture toughness of the material sintered with a lower amount of sintering aid remained relatively unchanged to 1200°C. The material with more additive exhibited decreased toughness above 1000°C