Speed- and topography-dependent boundary friction characteristics of steel

A novel tribometer that undergoes significant changes at ultra-slow (>5.0 mu m s(-1)) to moderate (<20 cm s(-1)) sliding speeds was developed in order to study the friction-speed characteristics of steel lubricated with oil. Three different surface topographies were applied to the specimens, and the friction characteristics with an additive-free base oil (MO91) and a stearic acid-formulated oil (StA/MO91) were studied to understand the effects of surface textures on the lubrication performance of an adsorbed molecular layer formed by StA. Friction reduction behaviour of the adsorbed layer observed in the transverse direction was attributed to microscopic hydrodynamic action that maintained the load-carrying performance of the adsorbed layer. Copyright (c) 2010 John Wiley & Sons, Ltd.