The tribological properties of nano-lubricants and their application on bearings: recent research progress

Good lubrication performance plays a vital role in reducing friction and ensuring stable operation of machine tool spindles. The performance of traditional lubricants has reached its limit and cannot meet the needs of the high-speed development of advanced equipment, and nanomaterials have attracted much attention due to their small size and excellent ability to repair defects on metal surfaces. Different nanomaterials, influencing factors, and surface modification methods have been extensively investigated for an in-depth understanding of the tribological performance of nano-lubricants. However, a comprehensive examination of the thorough classification of nano-additives, the revelation of nanoscale lubrication mechanisms, and their potential employs on bearings is lacking. This systematic review comprehensively investigates the types of nano-lubricants, tribological properties, and lubrication mechanisms. Recent advances in various numerical and experimental studies of different nano-lubricants for improving the performance of sliding bearings are summarized. The importance of utilizing nano-lubricants in bearing-rotor systems is emphasized and the limitations and main challenges in applications are analyzed. Future research should be devoted to the development of high-performance nano-lubricants to improve spindle performance and work stability.