Friction between Hard Rough and Soft Smooth Surfaces

Abstract

The metallic friction between a hard rough and a soft smooth surface has been investigated, in which the scratching of the soft surface by the hard asperities and the transfer of soft metal to the asperities could occur. Two effects of the metal transfer on the friction were found in the frictional experiments between low carbon steel and copper surfaces. One is an increase in the shearing component of the friction resulting from the sliding between softer metals, i.e., copper and copper. A second phenomenon due to the metal transfer is an increase in the cone angle of the hard asperities which could be assumed to have conical shape, and this causes a reduction in the ploughing component. The friction force could be evaluated from the height distribution of the asperities on the rough surface and the height of front ridge formed in front of the asperities, where the two effects of the metal transfer on the friction were also taken into account.