Influence of a Comb-Like Polymer Functionalized Phosphate Ionic Liquid as a Lubricant Additive on Micropitting

In this study, a comb-like polymer functionalized phosphate ionic liquid was synthesized and tested for its effectiveness in reducing friction and wear, as well as its capability to prevent micropitting in PAO base oil using SRV and MPR. It outperforms commercially available phosphate ionic liquids. The wear surface characteristics were analyzed using optical and electron microscopy, and changes in compound structure on the wear surface were studied using XPS spectroscopy. Through a combination of experimental observations and theoretical analysis, it is suggested that the lubrication mechanism is attributed to a synergistic effect between a “soft film” containing comb-like polymers formed through the adsorption of the ionic liquid, and a tribofilm consisting of phosphate compounds and a nitrogen-containing organic matrix.