Lubrication and wear reduction characteristics of graphene oxide/ionic liquid composite coating

Abstract

Graphene oxide (GO) exhibits good hydrophilicity and chemical harmonizability attributed to its extensive oxygen-containing functional groups, thereby conferring superior lubrication and wear reduction characteristics in water lubrication systems. In this study, a composite coating of graphene oxide/ionic liquids (GO/ILs) was prepared using impregnation and ultrasonic spraying techniques. The influence of GO, ILs on the lubrication and wear reduction characteristics of silicon carbide (SiC) was studied. Additionally, the coefficient of friction (COF), wear characteristics, and triboelectric characteristics of water-lubricated SiC interface were studied through alterations in speed and load. It was found that the GO/ILs composite coatings effectively enhanced friction lubrication properties by increasing the open-circuit voltage at the liquid-solid interface, thereby strengthening the mutual repulsive polarization electric field. Notably, the GO/ILs composite coating consistently delivered continuous and stable lubrication across a broad speed range under the combined support of ILs and the friction voltage effect. When the load exceeded 80 N, the COF for SiC with the GO/ILs composite coating consistently remained below 0.02 throughout the friction process. Remarkably, the COF of GO/ILs composite coating exhibited a substantial reduction of 92.36 % in comparison to uncoated SiC under conditions of 120 N and 1200 r/min. It was further revealed that the improved tribological properties of the GO/ILs composite coatings stemmed from the combined effect of the in-situ GO friction film, self-lubricating properties of GO, and coupled effect of the polarized electric field at the interface.