Imidazolium-based ionic liquids used as additives in the nanolubrication of silicon surfaces

Imidazolium-based ionic liquids used as additives in the nanolubrication of silicon surfaces

Blog Article

In recent years, with the development of micro/nanoelectromechanical systems (MEMS/NEMS), the demand for efficient lubricants of silicon surfaces intensified.Although the use of ionic liquids (ILs) as additives to base oils in the lubrication of steel/steel or other types of metal/ metal tribological pairs has been investigated, the number of studies involving Si is very low.In this work, we tested imidazolium-based ILs as additives to the base oil polyethylene glycol (PEG) to lubricate Si surfaces.The friction coefficients were measured in a nanotribometer.The viscosity of the PEG + IL mixtures as well as their contact angles on the Si surface were measured.

The topography and chemical composition of the substrates surfaces were oceane eau de toilette determined with atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), respectively.Due to the hygroscopic properties of PEG, the first step was to assess the effect of the presence of water.Then, a series of ILs based on the cations 1-ethyl-3-methylimidazolium [EMIM], 1-butyl-3-methylimidazolium [BMIM], 1-ethyl-3-vinylimidazolium [EVIM], 1-(2-hydroxyethyl)-3-methylimidazolium [C2OHMIM] and 1-allyl-3-methylimidazolium [AMIM] combined with the anions dicyanamide [DCA], trifluoromethanesulfonate [TfO], and ethylsulfate [EtSO4] were added to dry PEG.All additives (2 wt %) led to a decrease in friction coefficient as well as an increase in viscosity (with the exception of 8 oz red bull can dimensions [AMIM][TfO]) and improved the Si wettability.The additives based on the anion [EtSO4] exhibited the most promising tribological behavior, which was attributed to the strong interaction with the Si surface ensuring the formation of a stable surface layer, which hinders the contact between the sliding surfaces.