Processing defect analysis and nondestructive evaluation technology for Si₃N₄ bearing ball

Silicon nitride bearing balls with superior mechanical properties have great future in aerospace and super precision bearing applications. But surface defects on ceramic bearing balls can be brought at any manufacturing stage. Surface and subsurface defects significantly reduce the rolling contact fatigue lifetime. Initiation, propagation and nondestructive evaluation (NDE) of defects in the manufacturing procedures are reviewed. The key to successful processing of high strength ceramics is to avoid producing related defects. Many investigations show that material microstructures and defects, as well as mechanical processing parameters integrally influence the final surface quality. Many NDE technologies such as radiation, ultrasonic, dye-penetration and laser scatter have been studied for ceramic bearing balls surface inspection around the world. The difficulties to develop NDE system for ceramic bearing balls caused by the variety of defects and surface unfolding mechanism design have not been solved yet.