Due to their marginal vapour pressure and their non flammability ionic liquids are interesting substances for the lubricant technology. In addition, some ionic liquids possess interesting rheological and tribological properties, a high thermal and chemical stability and high surface tension. The tendency of cavitation is for ionic liquids significantly lower than for other materials. Some ionic liquids are also known to be corrosion inhibitors.
A model of the processes between rubbing surfaces is given in Figure 1. The lubricating oil has the function to minimize the friction between the construction parts and to reduce the wearing of the surfaces.
Figure 1: Model of the friction between two surfaces (a: Bond scission by shearing, b: orientation of the molecules, c: activity of nascent surface, d: exo-electron, e: friction heat).