The Synergistic Effect of DLC Coating and Diketone/Nanocopper Hybrid Additive in Marine Engine Oil

To enhance the boundary lubrication of the cylinder liner-piston ring, this study developed a diketone/nanocopper hybrid additive and investigated its interaction with reactive and non-reactive sliding surfaces. Compared to steel/steel contacts, the hybrid additive performed more effectively in the case of steel/DLC configuration. On the one hand, the lower surface energy of DLC led to a more substantial orientation effect of diketone, resulting in an elevated capacity for forming a lubricant film; on the other hand, the high hardness and chemically inert characteristics of DLC promoted the tribochemical polishing effect of diketone, resulting in a very smooth sliding interface. Based on the synergistic effect between DLC coating and the hybrid additive, a novel lubrication system with superior performance was established for marine engines.