Failure Prediction of Hot-Pressed Si₃N₄ Ceramics by NDE

Results are presented on the detection of critical flaws in hot-pressed Si₃N₄ with Fe inclusions by nondestructive evaluation (NDE) and fractographic observation. The NDE methods employed included (1) low-energy contact radiography with digital image enhancement and (2) through-transmission and backscatter ultrasonic imaging. A comparison of NDE and fractography results indicates that the backscatter ultrasonic method may be more suitable than low-kV contact radiography for the detection of near-surface flaws.