Tribological behaviour of protic ionic liquids with ammonium salts modified LABSA as lubricants and additives

Two typical protic ionic liquids with ammonium salts modified linear alkylbenzene sulfonic acid (LABSA) were synthesised, and their tribological behaviours used as both lubricants compared with PAO10 and additives in PAO10 were evaluated with an Optimol SRV-I oscillating reciprocating friction and wear tester. The results show that the two novel protic ionic liquids with ammonium salts modified LABSA exhibited excellent friction-reducing and anti-wear properties as lubricants and can also significantly improve the tribological performance of the base fluids as friction modifier additives. The worn surfaces were characterised by scanning electron microscope and X-ray photoelectron spectroscopy, indicating that the excellent anti-wear and friction-reducing performance could attributed to the boundary lubrication films that could contain both the tribochemical film composed of organic amine decomposed from the protic ionic liquids with ammonium salts and the stable chemical absorbed film through the interactions between the sulfonate anions and surface metallic atoms during the sliding process.