Failure mechanisms of surface friction and wear in ceramic bearing pairs under representative aero-engine operating conditions

The intrinsic brittleness of conventional ceramic materials has long limited the operational reliability and performance of ceramic bearings under extreme service conditions, such as elevated loads and high rotational speeds. Recent developments in ultra-tough, high-strength nano-Al₂O₃ ceramics present a promising avenue to overcome these limitations, offering a synergistic enhancement of fracture toughness and mechanical strength. In this study, the tribological behavior of nano-Al₂O₃ ceramic balls mated with 8Cr4Mo4V bearing steel discs is systematically investigated under conditions representative of aerospace bearing environments, with particular emphasis on interfacial friction characteristics and wear failure mechanisms. The results reveal that, under high-load and high-speed conditions, the predominant wear mechanism on the steel disc is abrasive wear, accompanied by oxidative degradation. Comparative evaluation with Si₃N₄ and 8Cr4Mo4V ball counterparts demonstrates that nano-Al₂O₃ exhibits markedly superior wear resistance. These findings offer valuable insights into the tribological performance of hybrid ceramic bearings and contribute to the material selection and design optimization for advanced aero-engine mainshaft bearing applications.