Depu Kumar Patro, B.D.K.Suvin, P.S.2026-02-032025Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, 2025, 239, 9, pp. 1129-113913506501https://doi.org/10.1177/13506501251351792https://idr.nitk.ac.in/handle/123456789/20104Ionic liquids (ILs) offer multifunctional capabilities as lubricant additives. However, many conventional ILs contain moisture-sensitive halogen-based anions that may hydrolyze to form corrosive halogen acids, leading to surface degradation. This study explored halogen-free, amine-based protic ionic liquids (PILs) as additives in polar base oil polyethylene glycol (PEG200). Anti-corrosion tests revealed that incorporating PILs into PEG200 significantly improves corrosion resistance. Lubrication tests performed at various PIL concentrations showed that the blend containing 5wt% PIL exhibited the best performance, reducing the friction coefficient by 26.12% and wear volume by 90.61% compared to neat PEG200. Spectroscopic analysis confirms the formation of a protective tribofilm within the wear tracks, consisting of oxy-organic compounds and metal oxides such as FeOOH, Fe<inf>2</inf>O<inf>3</inf>and Fe<inf>3</inf>O<inf>4</inf>. This tribofilm minimizes direct contact between sliding surfaces and facilitates effective lubrication. These findings demonstrate the potential of amine-based PILs as efficient and environmentally friendly additives for PEG-based lubricants. © IMechE 2025Contacts (fluid mechanics)Corrosion resistanceFrictionIonic liquidsIron oxidesLubricantsPetroleum additivesSteel corrosionTribologyWear of materialsAnti-corrosionFriction and wearGreen lubricantsLubrication /Oil solubleOil soluble additivePEG 200Protic ionic liquidsSoluble additivesTribofilmsSpectroscopic analysis