Physicochemical and tribological comparison of bio- and halogen-based ionic liquid lubricants

MH Rahman and T Liu and T Macias and M Misra and M Patel and A Martini and PL Menezes, JOURNAL OF MOLECULAR LIQUIDS, 369, 120918 (2023).

DOI: 10.1016/j.molliq.2022.120918

The friction and wear behavior of bio-based trihexyltetradecylphosphonium saccharinate P6,6,6,14 Sacc and halogen-based trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl) amide P6,6,6,14NTF2 ionic liquids (ILs) were studied to understand their lubrication mechanisms at steel sliding interfaces. The physicochemical and tribological properties of the ILs were characterized over a wide temperature range (10-120 celcius) to reflect the conditions present in wind turbine applications. Friction increased with increasing temperature for both ILs. At any temperature, P6,6,6,14Sacc had sig-nificantly higher viscosity that provided thicker lubricant films and, in turn, better friction and wear pro- tection than the halogen-based P6,6,6,14NTF2. P6,6,6,14Sacc also had lower density, comparable thermal stability, more favorable wettability, and better corrosion performance than P6,6,6,14NTF2. Simulations showed that the cohesion interaction energy was stronger for P-Sacc due to its smaller anion-cation distance. The higher viscosity and stronger cohesion of P6,6,6,14Sacc than P6,6,6,14 NTF2 contributed to the ability of the bio-based IL to form an effective adsorption film that reduced fric-tion and wear across a range of temperatures. (c) 2022 Elsevier B.V. All rights reserved.

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