Performance and anti‐wear mechanism of Cu nanoparticles as lubricating oil additives

Purpose The purpose of this paper is to study the tribological performance and anti‐wear mechanism of Cu nanoparticles as lubricating oil additives. Design/methodology/approach An end‐face wear testing apparatus is used to measure the tribological properties of Cu nanoparticles as lubricating oil additives and using a commercial SJ 15W/40 gasoline engine oil for comparison. Electrical contact resistance (ECR) is measured on a universal nano and micro tester‐2 tribometer to detect the formation of tribo‐film generated by Cu nanoparticulate additive. The worn steel surfaces are investigated by scanning electron microscope (SEM), energy dispersive spectra (EDS) and X‐ray photoelectron spectroscopy (XPS). Findings The results show that Cu nanoparticles used as an oil additive can improve the anti‐wear and friction‐reduction performance of SJ 15W/40 gasoline engine oil remarkably. The results of SEM, EDS and XPS show that a deposit film containing metallic copper can form on the worn surface, which has a film thickness of about 120 nm. Originality/value This investigation establishes a baseline of Cu nanoparticles used as lubricating oil additives under face‐to‐face contact work conditions. Thus, the results are reliable and can be very useful for further applications of Cu nanoparticle additives in industry.