Applications: Ionic liquids in surface protection

© Springer International Publishing Switzerland 2015. This chapter presents some research lines on ionic liquids applications, such as corrosion protection through coatings formation, lubrication and tribology. All these applications depend on physicochemical interactions of ionic liquid molecules with materials surfaces. In the case of corrosion protection, different aprotic ionic liquids, mainly imidazolium, pyrrolidinium or phosphonium derivatives, with different anions, and some protic ionic liquids and their interactions with metallic materials, such as steels or Li, Mg, Cu, Al and its alloys, have been studied obtaining, in some cases, high corrosion reduction efficiencies, up to 90%. In addition, ionic liquids can be used as synthetic liquid lubricants able to withstand very high temperatures without excessive thermal or oxidative degradation, showing very low friction coefficients and wear rates. Halogen-free ionic liquids are currently being developed to avoid corrosion or tribocorrosion of metallic surfaces and possible generation of toxic species. Different kinds of nanocomposites or two-component ionic liquids are also reviewed.