ABSTRACT
Looking for evidence of a link between friction and roughness, rst we discuss the experiments with emery paper and metal. Porgess and Wilman (1959) experimented with emery papers of varying roughness sliding over each other (Figure 5.1). Roughness was expressed as a mean particle diameter; larger diameter meant larger roughness. Avient, Goddard, and Wilman (1960) investigated the friction between emery paper with varying particle sizes and various metals (Figure 5.2). The COF increased with particle size,
as in the second part of the curve in Figure 5.1, eventually commencing in a slight decline for most metals considered.
