Ionic liquids (ILs) are considered as a new kind?of lubricant for micro/nanoelectromechanical system (M/NEMS) due to their excellent thermal and electrical conductivity.However, so far, only few reports have?investigated the tribological behavior of molecular thin?films of various ILs. Evaluating the nanoscale tribological?performance of ILs when applied as a few nanometersthick?film on a substrate is a critical step for their application?in MEMS/NEMS devices. To this end, four kinds of?ionic liquid carrying methyl, hydroxyl, nitrile, and carboxyl?group were synthesized and these molecular thin films?were prepared on single crystal silicon wafer by dipcoating?method. Film thickness was determined by ellipsometric?method. The chemical composition and?morphology were characterized by the means of multitechnique
X-ray photoelectron spectrometric analysis, and?atomic force microscopic (AFM) analysis, respectively.?The nano- and microtribological properties of the ionic?liquid films were investigated. The morphologies of wear?tracks of IL films were examined using a 3D non-contact?interferometric microscope. The influence of temperature?on friction and adhesion behavior at nanoscale, and the?effect of sliding frequency and load on friction coefficient,?load bearing capacity, and anti-wear durability at microscale?were studied. Corresponding tribological mechanisms?of IL films were investigated by AFM and ball-on-plane?microtribotester. Friction reduction, adhesion resistance,?and durability of IL films were dependent on their cation?chemical structures, wettability, and ambient environment
Y Mo,W Zhao,M Zhu,M Bai
Tribology Letters