Study on the Lubrication Performance and Mechanism of Silver/Modified Graphene Oxide Composite Additives

Under complex friction conditions, base oils usually exhibit insufficient friction-reducing and anti-wear performance, poor shear resistance of the lubricating film, and weak interfacial adsorption stability. Herein, graphene oxide (GO) was surface-modified with the silane coupling agent KH550 and compounded with Ag nanoparticles to fabricate a silver/modified graphene oxide (Ag/KGO) composite lubricant additive. The microstructure and chemical characteristics of the Ag/KGO composite were characterized by SEM, XRD, FTIR, and Raman spectroscopy. Tribological tests performed on a Si3N4/GCr15 friction pair demonstrated that the lubricant containing 0.15 wt% Ag/KGO achieved the optimal tribological performance, with the average friction coefficient decreasing to 0.053, 51.8% lower than that of the base oil, and the wear scar width and depth decreasing by 34.5% and 75.7%, respectively. Molecular dynamics simulations revealed that Ag/KGO enhanced the interfacial adsorption strength and improved the shear stability of the lubricating film. Mechanism analysis indicated that KGO facilitated the formation of a stable lubricating film at the friction interface, while Ag nanoparticles acted as nano-bearings. Their synergistic effect reduced interfacial shear resistance and alleviated wear. These findings provide theoretical support for the design and development of high-performance composite lubricant additives.