Manipulating the conversion of nanoscale wear debris into tribofilm for wear reduction of steel

Wear debris particles play a crucial role in frictional interfaces. Conventional understanding holds that debris accumulation causes severe wear. Interestingly, the debris from metal friction pairs includes anti-wear metal oxides generated by tribochemical reactions, which can form a protective oxidation film to resist wear. However, minimizing the abrasive damage caused by accumulated debris and using the anti-wear property of the metal oxides can be mutually exclusive. Here, a rational design of a coupling surface that manipulates nanoscale wear debris to resist further wear is reported. It consists of surface textures used to capture and temporarily store excess nanoscale wear debris, a deposited self-cleaning coating that subsequently helps transfer part of the captured debris into the sliding-contact interface, where it converts into a protective oxidation film. The coexistence of the two elements with contrasting properties in manipulating nanoscale wear debris considerably reduces wear under conditions of water lubrication, oil lubrication, and macroscale superlubricity. Our strategy achieves the manipulation and utilization of wear debris for anti-wear purposes. This work holds the potential to promote further investigation into the role of nanoscale wear debris and its utilization approaches.