| Abstract
| - Friction-force measurements between a silica sphere and a titanium dioxide wafer in electrolyte solutionswere made using an atomic force microscope. The effect of electrical double-layer interactions on theadhesion and the friction force were investigated as a function of pH. In contrast to taking frictionmeasurements in air, conducting the study in aqueous solution has allowed the surface separation, adhesion,and applied force to be controlled independently. Friction was found to be dependent only on the intrinsicforce. Friction was seen to be independent of pH. When a force law fitted to the measured data was used,the separation as a function of intrinsic force was likewise found by theoretical calculations to be independentof pH. It was concluded that friction was solely dependent on separation and that the effect of applied forceand electrical double-layer interactions served merely to change the separation. In addition, it was proposedthat a single layer of unbound water molecules effectively lubricated the surfaces.
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