Ionic Liquids as Extreme Pressure Additives for Bearing Steel Applications

Journal Article · Fri Aug 02 00:00:00 UTC 2024 · Tribology Letters

DOI: https://doi.org/10.1007/s11249-024-01898-6 · OSTI ID:2426405

Donato, Mariana T. ^[1]; Nautiyal, Pranjal ^[2]; Deuermeier, Jonas ^[3]; Branco, Luís C. ^[3]; Saramago, Benilde ^[4]; Colaço, Rogério ^[4]; Carpick, Robert W. ^[2]

---

1. Univ. of Lisbon (Portugal); NOVA Univ. Lisbon (Portugal); Univ. of Pennsylvania, Philadelphia, PA (United States)
2. Univ. of Pennsylvania, Philadelphia, PA (United States)
3. NOVA Univ. Lisbon (Portugal)
4. Univ. of Lisbon (Portugal)

The protection of steel surfaces from wear under extreme pressure conditions is of major importance in several industries as it provides better performance and longer life of machinery. The motivation for this work was to study the lubrication of steel by ionic liquids (ILs), which have recently emerged as greener alternatives to commercial lubricants and additives. Three ILs based on sulfur-containing anions, used as 2-wt% additives in polyethylene glycol base oil (MW 200; PEG 200), were tested in the lubrication of ASTM 52100 bearing steel contacts in extreme pressure conditions (under mixed lubrication with a Hertzian pressure of 1.12 GPa) using a mini traction machine (MTM). Due to the poor resistance to corrosion of bearing steel, a semi-ester of succinic acid derivative corrosion inhibitor (Lanxess RC 4801) was added to the mixtures at a 1 wt% concentration. The ILs 1-hexyl-methylimidazolium trifluoromethanesulfonate ([C₆mim][TfO]) and 1-hexyl-4-picolinium trifluoromethanesulfonate ([C₆-4-pic][TfO]) revealed promising results in terms of surface protection of bearing steel. In contrast, 4-picolinium hydrogen sulfate ([4-picH][HSO₄]) as 2-wt% additive to PEG 200 + 1% RC 4801 did not show any improvement in wear performance compared to neat PEG 200 + 1% RC 4801. PEG 200 + 2% [C₆mim][TfO] + 1%RC 4801 allowed for a decrease in wear up to ~ 76% and PEG 200 + 2% [C₆-4-pic][TfO] + 1%RC 4801 up to ~ 46% when compared with neat PEG 200 + 1% RC 4801. Optical microscopy images suggest the formation of an adsorbed layer, which was further supported by chemical analysis via x-ray photoelectron spectroscopy (XPS) data for [C6mim][TfO].

• Research Organization: Pixelligent Technologies LLC, Baltimore, MD (United States)
• Sponsoring Organization: USDOE; USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• Grant/Contract Number: EE0010211
• OSTI ID: 2426405
• Journal Information: Tribology Letters, Journal Name: Tribology Letters Journal Issue: 3 Vol. 72; ISSN 1573-2711; ISSN 1023-8883
• Publisher: SpringerCopyright Statement
• Country of Publication: United States
• Language: English