Task-Specific Oil-Miscible Ionic Liquids Lubricate Steel/Light Metal Alloy: A Tribochemistry Study

In order to increase the solubility of ionic liquids in base oils and to improve the lubricating performance of light alloys, two new ionic liquids comprised of sulfonate base anion and phosphonium based cation are designed and synthesized. The difference between these two ionic liquids is the cation: One has only one organophosphate group (P₈₈₈₁₆DOSS) and the other has two organophosphate group (P_888PDOSS). The copper strip corrosion test is used to evaluate the anticorrosion properties of new developed ionic liquids. Tribological properties of the ionic liquids are investigated by an optimal SRV-IV oscillating tribometer. The results indicate that the new designed ionic liquids show very good solubility in traditional mineral-based oils. P₈₈₈₁₆DOSS and P_888PDOSS show excellent friction reduction, antiwear performance accompanied with effective anticorrosion properties for the mineral base oil. Surface analysis results show that the superior properties of P₈₈₈₁₆DOSS and P_888PDOSS are attributed to surface chemical reactions between ionic liquids and light metal.