Failure analysis of two hybrid bearing balls under heavy loads and extremely low temperature conditions

Surface spalling took place on hybrid bearing balls under heavy loads and extremely low temperature conditions in six hours. Fractographic and metallographic analyses were performed to study the potential cause of ceramic ball failure. The same failure mode was found in both the present experiment and rolling contact fatigue experiments on pre-existing surface crack Si₃N₄ bearing balls. Failure in this case was caused by propagation of pre-existing surface cracks induced from large inclusions. Material assurance methods and nondestructive inspection must be directly introduced into the manufacturing process to prove mechanical properties of hybrid bearing balls.