Alcohol adsorption lubrication from

The surface of all inorganic materials exposed to ambient (humid) air is always covered with a thin layer of water adsorbed from the gas phase. The thickness of the adsorbed water layer varies with the humidity and surface chemistry. This water layer has been shown to reduce wear in MEMS operation. However, the high surface tension of the water film can cause an in-use stiction problem. The gas-phase lubrication concept discussed here employs the same equilibrium adsorption principle as the water adsorption in humid environments. The difference is that our approach utilizes a surfactant-like molecule that can provide low adhesion and good lubrication. The entry summarizes the advantages of gas-phase lubrication for MEMS devices and discusses the effect of alcohol adsorption on the adhesion and lubrication of silicon oxide surfaces. 

Similar conclusions may be drawn from the experiments of Hardy on lubrication. Hardy has obtained very convincing data in support of the hypothesis that on the adsorption of a vapour such as octyl alcohol by a metal surface, whilst the first layer is held very tenaciously the thickness of the film of vapour condensed on the metal surface which is in equiUbrium with the free surfeice of the liquid is certainly multimolecular in character and those layers forming the secondary film may be squeezed out by application of sufficient pressure. 

The contact of a lubricating substance with a solid is particularly significant from a tribological point of view. Oxyethylated alcohols are nonionic surfactants, and their interactions with the surface are basically quite specific (hydrogen bonds). The contribution of universal (electrostatic) interactions is considerably smaller, as these are very weak dispersion interactions. In the solution in contact with a solid, one can distinguish the surface phase and the bulk phase. Due to adsorption from solutions, the surface phase is enriched with the component that has a stronger affinity for the surface. It is a characteristic of adsorption from solutions on a solid surface that individual components compete for free sites on the surface. At this point, one should not confuse adsorption with absorption, the latter of which may lead to penetration of the components into the solid. 

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