Tribological Characteristics of Protected Silver Nanoparticles in Oil

In recent years, there has been considerable interest in employing dispersed solid particles in the nanoscale range to enhance the friction and wear characteristics of liquid lubricants. Previous studies have suggested that tiny colloidal particles, under tribochemical conditions, deposit on rubbing surfaces influencing tribological characteristics of the contact. This article presents a study of the tribological behavior of stabilized silver nanoparticles dispersed in n-hexadecane. Friction and wear measurements are combined to investigate the extent to which colloidal solid particles influence a lubricated contact. It is shown that the silver nanoparticles studied contribute to reduce friction and wear only in the thin film regime. Nanoparticles help to reduce friction and wear down to a certain concentration value. Higher concentrations of nanoparticles do not bring any further contribution to reduce friction or wear, suggesting the existence of an optimum concentration of nanoparticles.