Graphene and its derivatives are widely recognized as effective reinforcements due to their unique mechanical, thermal and lubrication performance. Incorporation of these reinforcements into polyamide-imide (PAI) coating matrix has shown significant potential for improving the tribological performance. Here, the mechanisms underlying the tribological improvement enabled by graphene oxide (GO) are investigated via frictional experiments and molecular dynamics simulations. It was found that the coefficient of friction (COF) of PAI coating is reduced upon the addition of GO over the range of 100–400 MPa and 20–100 mm/s, with a maximum reduction of ~25% achieved at 200 MPa and 60 mm/s. Simulations reveal that the friction reduction arises from strong adhesion interactions between the embedded GO sheets and PAI molecular chains, which inhibit the shear-induced mobility of the chains during the friction process. This mechanism enables a further reduction in the COF of the GO/PAI composite coating by increasing the interfacial adhesion through the tailored modulations of surface morphology and chemistry of the GO sheets. These findings pave the way for advancing the rational design and application of graphene-based composite coatings with highly improved tribological performance.
Shi et al. (Sun,) studied this question.