Pyrrolidinium sulfate and ammonium sulfate ionic liquids as lubricant additives for steel/steel contact lubrication

Abstract

In this work, we report on the BuMepyr-MeSO₄ and Et₃MeN-MeSO₄ ionic liquids that were synthesized and used as additives in a glycerol model lubricant for steel/steel contacts. Tests were performed with three different ionic liquid concentrations, i.e. 0.625 wt%, 2.5 wt% and 8 wt%, as well as in glycerol without any ionic liquid (neat glycerol) and in neat ionic liquids (100%) at 100 °C. The wear and friction were measured and the worn surfaces were examined with scanning electron microscopy and atomic force microscopy. The results show a reduction of the wear and friction with the use of ionic liquids as additives, when compared to the neat glycerol. With an increasing ionic-liquid concentration in the glycerol, the friction was observed to decrease and the wear to increase. In this work, however, the results obtained for neat ionic liquids represent the lowest values in terms of both friction and wear.