Tribological Investigation of Guanidinium Ionic Liquids as Lubricants for Steel/Bronze Contacts

Abstract

Two kinds of guanidinium ionic liquids were synthesized. The thermal stabilities of the ionic liquids were evaluated by a hermogravimetric analyzer. Their tribological properties were investigated and compared with alkyl imidazole ionic liquids and liquid paraffin by SRV friction-wear test. The images of worn surfaces were observed under scanning electron microscope. X-ray photoelectron spectrometer analysis was carried out to explore the lubrication mechanism. The results showed that guanidinium ionic liquids were the best lubricants among the tested lubricants for steel/bronze contacts. Complex tribochemical reactions occurred during the sliding process and boundary lubrication films formed on the bronze/steel friction pair interface.