Achieving robust ultralow friction and wear through multiscale synergistic lubrication design

Achieving robust ultralow friction and wear with oil lubrication system remains a major challenge, which is crucial for ensuring the reliability and durability of high-end mechanical systems, such as aerospace engines and wind turbine gearboxes. In this work, a multiscale synergistic lubrication strategy is proposed that combines polyether-modified silicone oil, glycerol trioleate (GT) and carboxylated graphene quantum dots (CGQDs), aiming to realize a robust ultralow friction and wear state for steel tribopairs across a broad range of test conditions. The results show that PESO oil could induce the formation of a near-superlubricious tribofilm under high reciprocating frequency of 15 Hz; however, this tribofilm could not be effectively sustained under a low reciprocating frequency of 5 Hz. When polar glycerol trioleate and CGQDs nanoadditve are introduced into PESO base oil as lubricant additives, extremely low friction and wear could be realized over a wide range of loads and frequencies. Detailed characterization reveals that this superior performance is attributed to the multiscale synergistic lubrication effect of the polar PESO base oil, polar glycerol trioleate, and CGQDs, during which these components synergistically promote the in-situ formation of a robust lubricating film. This in-situ formed robust tribofilm could not only effectively passivate the rough surface contacts but also provide an shearable interface. It could expect that this research will provide a new lubricious strategy for the further development of high-end mechanical equipment with higher performance.