Tribological properties of surfaces (friction,\nadhesion and wear) provide challenging limitations to the\ndesign of reliable machines on the micro- and nanometer\nscale as the surface to volume area increases and volume,\nmass and inertia of the mobile parts decrease. This study\nreports on the reduction in the friction force of silicon\nsurfaces after the alkali metal ion exposure in the form of\naqueous solutions. A scanning force microscope equipped\nwith a liquid cell was used to investigate the friction force\nand the pull-off force of a flat silicon surface immersed in\nwater and in different alkali metal chlorides solutions:\nLiCl, NaCl and CsCl. The concentration ranged from 0.1\nup to 1000 lmol/l. The changes in the free surface energy\nof the initial surface and of the modified surfaces after\ndrying were determined from contact angle measurements\nand from the acidââ?¬â??base adhesion theory. In both cases, in\nthe liquid environment and after drying of the exposed\nsilicon substrates in air, the friction force is reduced by\napproximately 50 %. Our results provide new, fundamental\ninsight into the exchange of surface termination layers in\nparticular for tribology. Also it is suggested to use the\nprocedure as a low-cost alternative to improve the tribological\nproperties of the silicon surface in particular in\napplications where lubricating fluids are not appropriate,\ne.g., in nanomachines and devices.
Loading....