Dinesh G. Bansal

Antiwear performance and mechanism of an oil-miscible ionic liquid as a lubricant additive.

An ionic liquid (IL) trihexyltetradecylphosphonium bis(2-ethylhexyl) phosphate has been investigated as a potential antiwear lubricant additive. Unlike most other ILs that have very low solubility in nonpolar fluids, this IL is fully miscible with various hydrocarbon oils. In addition, it is thermally stable up to 347 °C, showed no corrosive attack to cast iron in an ambient environment, and has excellent wettability on solid surfaces (e.g., contact angle on cast iron <8°). Most importantly, this phosphonium-based IL has demonstrated effective antiscuffing and antiwear characteristics when blended with lubricating oils. For example, a 5 wt % addition into a synthetic base oil eliminated the scuffing failure experienced in neat oil and, as a result, reduced the friction coefficient by 60% and the wear rate by 3 orders of magnitude. A synergistic effect on wear protection was observed with the current antiwear additive when added into a fully formulated engine oil. Nanostructure examination and composition analysis revealed a tribo-boundary film and subsurface plastic deformation zone for the metallic surface lubricated by the IL-containing lubricants. This protective boundary film is believed to be responsible for the ILs antiscuffing and antiwear functionality.

Characterization and Tribological Evaluation of 1-Benzyl-3-Methylimidazolium Bis(trifluoromethylsulfonyl)imide as Neat Lubricant and Oil Additive

Selected physical and chemical properties and tribological data for a newly-developed, imidazolium-based ionic liquid (IL) are presented. The IL is soluble in the SAE 5W-30 oil up to a certain weight percentage, and is as a promising candidate for use in lubrication applications, either in its neat version or as an oil additive. Characterization of the IL included dynamic viscosity at different temperatures, corrosion effects on cast iron cylinder liners, and thermal stability analysis. The tribological performance was evaluated using a reciprocating ring-on-liner test arrangement. When used in neat version this IL demonstrated friction coefficient comparable to a fully formulated engine oil, and when used as an oil additive it produced less wear.Copyright