Ionic liquids in tribology

Resumen

Lubrication and surface protection is mandatory in such strategic sectors as transportand energy production. The reduction of energy loss due to friction and wear ofmaterials accounts for several points of the Gross Domestic Product (GDP) indeveloped countries.Present environmental regulations make it necessary to substitute currently usedconventional lubricants and lubricant additives for alternative formulations free fromhalides, sulphur, heavy metals and other potentially toxic or hazardous elements.In our research group, we are currently studying the potential applications of roomtemperature ionic liquids (ILs) in tribology, surface engineering and nanotechnology.The ability of ILs to form adsorbed ordered thin films on sliding surfaces has been usedto develop new self-lubricating surfaces and materials.Modification of nanophases, in particular carbon nanomaterials such as graphene,carbon nanotubes and nanodiamonds, by ILs has given rise to new ‘ionanofluids’ [1]which are currently being characterized and studied as lubricants and lubricant additivesin order to reduce friction coefficients and surface damage of materials under severecontact conditions.Addition of the new ionanofuids to polymer matrices has allowed the development ofnew ‘ionanocomposites’ [2] with improved tribological performance, including selflubrication and self-healing of surface damage produced under sliding conditions.For those highly reactive materials, where lubrication is not able to avoidtribocorrosion, ILs are being tested as precursors of protective coatings [3].A variety of protic and aprotic IL formulations, both commercial and newly synthesizedwill be discussed.