Corrosion and lubrication properties of a halogen-free Gemini room-temperature ionic liquid for titanium alloys

A halogen-free Gemini ionic liquid (IL N18-2-18P8) was designed and synthesized by combining dis-quaternary ammonium cations with phosphate ester anions. The tribological and corrosion performance of the N18-2-18-P8 was compared with that of a polymerized alpha olefin (PAO) and traditional halogen ionic liquid (P104) as a lubricant for titanium alloy sliding against steel. The results show the N18-2-18P8 presents the highest kinematic viscosity but lower friction coefficient (FC) and higher anti-wear (AW) than P104 and PAO. Simultaneously, N18-2-18P8 also negligibly corrodes the titanium at room temperature (RT) and 100 °C (HT). The corrosion characteristics, friction and wear mechanisms were analyzed by FC measurements, SEM, EDS, XPS, and TOF-SIMS.