Effects of graphene oxide solvent-free nanofluids on the tribological properties of polyimide coating

A novel organic coating was created by dispersing solvent-free covalent graphene oxide nanofluids (GO NFs) into a polyimide (PI) matrix. The tribological properties of GO NFs/PI composite coatings was tested against ball-on-disk tribometer. Even a low loading of GO NFs significantly improve the tribological properties of PI. MD simulation and nanoindentation tests reveal that GO NFs adsorbs the PI molecular chains, enhancing the composites' mechanical properties. Moreover, a stable tribofilm develops on the steel ball surface lubricated with the GO NFs/PI composite coating, with analyses indicating that the GO NFs promote its growth. The enhancement of mechanical properties and the formation of this tribofilm are essential for the improved tribological performance of the composite. This research aims to contribute to the development of novel PI composite coatings with superior anti-friction and wear-resistant properties. Highlights The GO NFs exhibited excellent dispersion stability and tribological properties. Novel GO NFs/PI composite coating with significantly enhanced tribological properties. A carbon-based tribofilm forms on the steel ball. The strengthening mechanisms of composites were revealed by MD simulation.