Performance of oil-soluble ionic liquids as novel lubricant additives

Two new oil-soluble ionic liquids (ILs) with the same anion but different cations, N88816-Doss (N/S) and P88816-Doss (P/S), have been synthesized in this study. Three traditional lubrication additives, T321, T204, and T306, were added to PAO10 at specified ratios; five lubricants based on PAO10 were prepared. The effect of differences in the molecular structure between the two new ILs and traditional lubricant additives was systematically studied in terms of their tribological properties. The results demonstrated that N/S significantly improved the physicochemical and frictional properties of PAO10. When N/S was added to PAO10, the friction coefficient was reduced by approximately 50 %, while the wear volume was reduced by approximately one order of magnitude. The lubrication mechanism was validated by scanning electron microscopy, energy dispersion spectrometry, and X-ray photoelectron spectrometry. The results revealed that when N/S is used as a lubricant additive, a chemically reactive film containing the active elements N and S is formed between the steel/steel friction pair. This film plays an important role in reducing friction and wear during the friction process.