Densification behaviors and high-temperature characteristics of Si3N4 sintered bodies using Al2O3-Yb2O3 additives

High room temperature strength of 900-1000 MPa was obtained for sintered bodies with a 10.0 mass% addition of additives, and this is considered to be due to the finer micro-structure. Precipitation of a Yb4Si2N2O7 phase at the grain boundary glass phase, as induced by crystallization processing, enables the improvement of 1300 °C strength to about 650-720 MPa. Crystallization processing resulted in a 30% reduction in the amount of weight change during oxidation (from 3.42 to 2.46 mg/cm2), demonstrating the effectiveness in improving oxidation resistance.