Tribological study of the AISI316L/Sapphire contact with self-lubricating films of protic ionic liquids

Ionic liquids have shown an outstanding performance as lubricants in different contacts. Protic ammonium carboxylate ionic liquids (PILs), both neat and as additives in water, are being studied as friction-reducing and wear prevention lubricants in stainless steel-sapphire contacts. When a PIL was used as additive in water, the high temperature reached at the sliding contact produced the evaporation of water and the formation of a low friction PIL boundary layer. In the present study, the formation of the PIL boundary layer on AISI316L stainless steel under static conditions is described and its lubricating performance against sapphire balls has been studied. The effect of relative humidity has been studied using a vacuum chamber. The results described in the present study show a good tribological performance of these thin surface films, in pin-on-disc tests, reducing the running-in period of high friction coefficient, preventing wear and reducing the volume of lubricant with respect to the results obtained when water+1%PIL and neat PIL are used as lubricants.Competitividad (MINECO, Spain) (MAT2011-23162 and MAT2014-55384-P) for financial support. T. Espinosa is grateful to the Ministerio de Educación, Cultura y Deporte (MECD, Spain) for a research Grant (AP2010-3485)