Semi-Empirical Molecular Modeling of Ionic Liquid Tribology: Ionic Liquid–Aluminum Oxide Surface Interactions

Abstract

The interactions between the selected ionic liquids (ILs) and aluminum oxide surfaces are modeled in this report using theoretical methods. A wide range of ILs and their interactions with an aluminum oxide surface are modeled using the PM5 semi-empirical method. The ILs modeled in this study contain imidazolium (C 3, 4, 6, 8 or 10 mim) or ammonium cations including (C 6 H 13 ) 3 NH ? , (C 8 H 17 ) 3 NH ? , C 8 H 17 NH 3? , (C 2 H 5 ) 3 NH ? , and (C 8 H 17 )NH 3 ? . The anions include Cl -, Br -, PF 6 -, (CF 3 SO 2 ) 2 N -, and (C 2 F 5 SO 2 ) 2 N -. The interactions of these ILs with an Al-O surface are modeled in a stepwise manner. The lowest energy forms of the individual ILs are determined, and these ILs are allowed to form a complex with the Al-O surface. The resulting reaction enthalpies of ionic liquid-surface complex formation are seen to correlate with the tribological properties of the ILs. The strongest correlations occur within those ILs containing similar cations.

Short alkyl chain imidazolium ionic liquid additives in lubrication of three aluminium alloys with synthetic ester oil

“…The correlation between wear and hardness observed for the additivated oils but not for the base oil can be attributed to the interaction between the ionic liquid molecules and the surface layer on Al7075. 25 This alloy is the hardest and more corrosion resistant of the three aluminium alloys studied here. 24 Fig.…”

Correlation between Structural and Tribological Characteristics of Some Mesomorphic Boundary Lubrication Layers

“…These calculations help to estimate the effects arising directly at a friction of metal and/or nonmetallic surfaces in vacuum, in the presence of liquid lubricant or nanoparticles. In this connection researches on presence or absence of «third body» in a contact zone can be classified as 1) at a solid friction with lack of any environment [2,3,4]; 2) in gas environment or in the presence of air; 3) in the presence of thin dividing films in condensed condition; 4) in the presence of lubrication films [1,6], including ionic liquids [7].…”