Ultralow friction together with superlow wear achieved with polyether-modified silicone oil grease

The development of superlubric grease has garnered enormous attention in industrial applications. In this work, silicone oil has been modified with polyether functional group to effectively interact with steel substrate, making a contribution to forming a favorable superlubric tribochemical tribofilm. The synthesized polyether-modified silicone oil (PESO) has been further formulated with a sebacic acid-based lithium thickener, whose entangled morphology could effectively interact with PESO oil molecules, endowing it with significant thickening performances. The tribological results show that the PESO oil-based grease with 5 wt% of sebacic acid-based lithium thickener exhibits an extremely low COF of 0.027 combined with a superlow wear rate of 3.2 × 10⁻⁹ mm³N^₋1m^₋1 for steel tribopairs. The remarkable tribological performance could be attributed to the in-situ release effect of oil molecules, triggering favorable tribochemical reactions with friction surfaces and inducing the in-situ formation of a superlubric tribofilm at the friction interface. Furthermore, the sebacic acid-based lithium thickener could also effectively support load and prevent the serious asperity contacts of tribopairs, creating a desirable synergistic lubrication effect with PESO oil molecules and thereby contributing to the achievement of superlow wear. It could be expected that the findings of this study could lay a solid foundation for advancements in superlubric grease technology.