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.

A review of recent developments of friction modifiers for liquid lubricants (2007–present)

“…SEM and XPS results indicated that the excellent anti-wear and friction-reducing performance could be attributed to the boundary lubrication films containing both the tribochemical film composed of organic amine decomposed from the ILs with ammonium salts and the stable chemical adsorbed film through the interactions between the sulfonate anions and surface metallic atoms during the friction process [177]. Besides, the ammonium sulfate (96) and pyrrolidinium sulfate (97) ILs were reported as lubricant additives with a reduction of wear and friction for steel/steel contacts [178]. It was observed that the friction decreased and the wear increased with the increasing ILs concentration due to the competing abrasioncorrosion wear mechanisms.…”

A Review of Ionic Liquid Lubricants

“…Table 4 gives a) b) a summary of the ionic liquids and base oils used and their performance in wear tests for various systems. Ionic liquids have been added to a number of base oils, such as hydrocarbons, polyethylene glycol (PEG), polyalphaolefins (PAO) propylene glycol dioleate (PGDO) and glycerol [7,16,17,27,[29][30][31][43][44][45][46]52,53,[68][69][70]. The amount of IL added to base oils has varied from 0.3 wt% to 10 wt%, with the proportion depending on the solubility and the amount required to give the best performance [16].…”

Pyridinium based dicationic ionic liquids as base lubricants or lubricant additives

“…For all these reasons, we have synthesized and studied the tribological properties of a series of DILs that incorporate polyethylene glycol chains linking two alkylpyridinium moieties. Alkylsulfate [RSO 4 ] and bis(trifluoromethane) sulfonimide [NTf 2 ] were selected as anions taking into account the reduction on wear and friction observed when these anions were used in previous works on monocationic ILs [20,21].…”