Application of Nanoparticles in Lubricants

Nanomaterials have great potential as lubricating materials or for development of advanced lubrication technology. Recently, nanoparticles as oil additives have gained more and more attention for purpose of reducing friction and wear. It has been found that various inorganic nanoparticles such as sulfides, oxides, rare earth fluorides, and copper as oil additives are capable of considerably reducing wear and increasing loadcarrying capacity. This could be attributed to the formation of a boundary film composed of the deposited nanoparticles and the tribochemical reaction products of the active elements in the lubricants with the lubricated metal surfaces, which has been testified by the analysis of the worn surface with of Xray photoelectron spectroscopy and scanning electron microscopy. The inorganic nanoparticles as lubricating oil additives are also capable of healing the worn metal surfaces, owing to its strong activity and interaction there with. However, further work is needed to decrease the cost of nanoparticles by realizing largescale production, before they find wide industrial application. It is thus suggested to focus on the study of novel methodology for the preparation of nanomaterials and on the development of novel multifunctional and environmentally friendly nanoparticles as lubricating oil and grease additives.