Abstract
Ionic liquids (ILs) have been receiving considerable attention from the lubricants industry as potential friction and wear-reducing additives, but their solubility in oils is an issue. Unlike most ionic liquids that are insoluble in non-polar hydrocarbon oils, this study reports phosphonium-based ILs (PP-ILs) that are fully miscible with both mineral oil-based and synthetic lubricants. Both the cation and anion in quaternary structures, long alkyl chains, and capability of pairing the cation and the anion via a H-O bond are hypothesized to improve the compatibility between ions and neutral oil molecules. The measured viscosities of the oil-IL blends agree well with the Refutas equation that is for solutions containing multiple components. High thermal stability and non-corrosiveness were observed for the PP-ILs. Effective friction reduction and anti-wear functionality have been demonstrated in tribological tests when adding 5. wt% of a PP-IL into a base oil, suggesting potential applications for using the oil-miscible PP-ILs as lubricant additives.
Original language | English |
---|---|
Pages (from-to) | 58-64 |
Number of pages | 7 |
Journal | Wear |
Volume | 289 |
DOIs | |
State | Published - Jun 15 2012 |
Funding
Research sponsored by the Vehicle Technologies Program, Office of Energy Efficiency and Renewable Energy, US Department of Energy (DOE). Part of the IL synthesis effort was supported by the DOE Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. B. Yu, D.G. Bansal, and X. Sun acknowledge the Oak Ridge Associated Universities for postdoctoral fellowships.
Keywords
- Additives
- Anti-wear
- Lubricants
- Miscibility
- Phosphonium-based ionic liquids
- Solubility