Effect of trace moisture on friction

Abstract

We report that even in nominally dry conditions trace moisture present on hydrophilic surfaces of SiC leads to a considerable increase in friction via formation of hydrogen bonds across the sliding interface. We perform quantum mechanical calculations to demonstrate that frictional instabilities on such surfaces are related to formation and breaking of hydrogen bonds between surface hydroxyl groups and to the elastic rotation of these groups. We perform a theoretical analysis based on the modified Prandtl–Tomlinson model and we predict that in the presence of trace moisture friction force will have logarithmic dependence on the sliding velocity.