Preparation of Cu@SiO2composite nanoparticle and its tribological properties as water‐based lubricant additive

In this paper, to solve the problem that di‐n‐hexadecyldithiophosphate (DDP)‐modified Cu nanoparticles initially used as oil‐based lubricant additive cannot be directly used in water‐based lubricants, we adopt a water‐in‐oil reverse micro‐emulsion method to incorporate hydrophobic Cu nanoparticles into silica spheres for obtaining water‐dispersible Cu@SiO2nanoparticles. The effects of reaction conditions on the morphology and microstructure of Cu@SiO2nanoparticles were investigated. Furthermore, the tribological properties of the as‐prepared Cu@SiO2nanoparticles as a lubricant additive in distilled water were investigated with a UMT‐2MT tribometer. Results indicate that the as‐prepared Cu@SiO2nanoparticles exhibit good dispersion stability and antioxidant ability in distilled water. Besides, Cu@SiO2nanoparticles can significantly improve the tribological properties of distilled water, which is attributed to the formation of a protective and lubricious film consisting of Cu, FeS and SiO2on the rubbed steel surface.