α/β-Sialon ceramics and its fatigue life

Abstract The investigations were focused on the phase composition, microstructure and fatigue life of α/β-sialon ceramics prepared from powder mixtures of Si 3 N 4 , AlN, Al 2 O 3 and Y 2 O 3 by gas pressure sintering. The results obtained show that the sialon ceramic material is mainly composed of 70% β-sialon, 30% α-sialon with a small amount of crystalline phase and glassy phase at the grain boundaries. The cyclic fatigue life testings were conducted on Instron 8501 servohydraulic machine operating under load control, with a sinusoidal wave form at a frequency of 25 Hz and stress ratios ( R ) of 0.1. The operations lead to the result that the fatigue limit stress is about 75% static strength for this material.