Tribological properties of Al2O3 nanoparticles as lubricating oil additives

Nano-scale Al2O3 spherical particles, prepared via a hydrothermal method and modified by silane coupling agent, can be well-dispersed in lubricating oil. The tribology properties of Al2O3 nanoparticles as lubricating oil additives have been studied by four-ball and thrust-ring friction test, which illustrate that the modified Al2O3 nanoparticles can effectively improve the lubricating behaviors compared to the base oil. When the added concentration is 0.1 wt%, the friction coefficient and the wear scar diameter are both smallest. The lubrication mechanism is that a self-laminating protective film is formed on the friction surface and the wear behavior changes from sliding friction to rolling friction.