Improved tribological performance of epoxy self-lubricating composite coating by BNNSs/Ag

Abstract

The application of epoxy (EP) self-lubricating composite coatings to the surface of mechanical parts has attracted attention increasingly, since they are beneficial for extending the lifetime of equipment by decreasing friction and wear. However, the shortcoming of poor wear resistance of EP is a limited factor in tribology. In the present study, the hard hexagonal boron nitride nanosheets (BNNSs) supported soft metal of Ag nanoparticles (Ag NPs) was constructed to strengthen the tribological performance of EP. The BNNSs was firstly prepared after h-BN being treated by NaOH/KOH solution, and then Ag NPs were uniformly anchored on the BNNSs surface through hydrothermal method. The achieved BNNSs/Ag surface had rough microstructure and active sites, which were conducive to the interfacial compatibility between BNNSs and EP. The tribological test results demonstrated that the lubricity and wear resistance of EP coating were improved significantly by BNNSs/Ag. Especially as the weight fraction of BNNSs/Ag was 0.7 %, the corresponding composite coating showed an 80.5 % and 86.4 % reduction in the friction coefficient and wear rate compared to EP coating, which was mainly because of the good interfacial interaction in the composite coating, the “hard-soft” synergistic reinforcing and lubricating effect of BNNSs/Ag, as well as self-lubricating property of transfer film. Furthermore, the tribological behaviors of BNNS/Ag/EP composite coating under pure water and oil lubrication were investigated comparatively. The enhancement mechanism of BNNSs/Ag was proposed by analyzing the worn surface of composite coatings and counterparts.