Friction and Wear Behaviors of PI/MoS₂ Bearing Cage Composite Under Elevated Temperature Conditions

The drive systems of new energy vehicles, which employ high-speed motors and low-viscosity lubricants, often subject motor bearings to high-temperature and oil-starved conditions. This can lead to the deformation of polymer bearing cages, resulting in abnormal vibration and noise. In this study, polyimide/molybdenum disulfide (PI/MoS₂) composites were prepared, and their thermal stability was characterized using a dynamic mechanical analysis (DMA). High-temperature friction and wear tests against ceramic balls were conducted on a multifunctional tribometer. The wear behavior and surface element distribution were examined by laser confocal microscopy (LCSM), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). Results indicate that the PI-MoS₂ composites effectively mitigate surface contact deformation with rising temperatures, reducing the wear loss by around 30% compared to pure PI. This improvement is attributed to the enhanced heat resistance from MoS₂ and the formation of a lubricating film during friction. The findings provide guidance for selecting and designing composite materials for high-speed bearing cages.