Electrochemically reduced graphene oxide nanosheet coatings as solid lubricants in humid air

Highlights: • A facile, low cost and green approach to fabricate ERGO coatings is reported. • The feasibility of using ERGO coatings as solid lubricants is demonstrated. • ERGO coatings reduce copper's COF to 1/6 and wear rate to more than 1/260. - Abstract: A facile, low cost and green approach to fabricating graphene nanosheet coatings is reported. It is composed of spraying graphene oxide (GO) suspension to form GO nanosheet coatings followed by a low voltage electrochemical reduction process. The tribological performance of the as-prepared electrochemically reduced graphene oxide (ERGO) nanosheet coatings on copper disk are evaluated by sliding against steel ball in humid air. The friction coefficient of copper is reduced to 1/6 its value, and its specific wear rate is reduced more than two orders of magnitude when copper disk is coated with ERGO nanosheet coatings. These improved tribological performance are attributed to the presence of ERGO nanosheets in the sliding interface of steel vs. copper friction pair. They not only provide easy shearing, reducing the friction coefficient, but also effectively suppress abrasive wear and adhesive wear, decreasing the wear rate of copper disk.