Análise dos parâmetros de deposição e nanotribológica de dois líquidos iônicos em um substrato de silício

Abstract

Two phosphorus-based Ionic Liquids (ILs) were deposited onto a <111> silicon substrate via dip coating. These ILs, trihexylttetradecylphosphonium bis(2,4,4-trimethylpentyl) phosphinate and tetrabutylphosphonium methanesulfonate, are two possible candidates for the lubrication of micro/nanoelectromechanical devices (MEMS/NEMS). To evaluate this, their abilities to form a thin adsorbed film (1 to 100nm) on the silicon surface were studied. Variations were made in deposition parameters such as substrate cleanliness, different concentrations, and deposition speed. The surface was followed by optical microscopy, with the aid of an atomic force microscope (AFM). As a result, it was possible to observe the topography, the variation of the friction force as a function of the applied normal load and the adhesion force between the tip and the film. In addition, a confocal Raman spectroscopy (532 nm laser and 7.2 mW power) was used to observe the presence of ionic liquid in specific regions of interest. Using these tools, it was possible to observe a different behavior in the friction coefficient and in the film formation mechanism on the surface between the two lubricants, which can be attributed to the fact of difference in the size of the cation chain and consequently in its adhesion force.