Theoretical surface temperatures generated from sliding contact of pure metallic elements

Surface temperatures and thermal effects produced in tribological processes are important not only in influencing possible mechanisms of friction, wear, and lubricant film failure but also in initiating protective film-formation. As part of a continuing combined theoretical and experimental study of surface temperatures generated by friction, the fundamental Greenʹs function approach has been applied to a number of pure metallic elements to compare and discuss their predicted behavior in A-on-A sliding contact. Assuming a single area of real contact, calculated ratios of surface temperature rise to coefficient of friction plotted against area of contact, velocity and load on a logarithmic scale are presented and summarized for several pure metallic elements in the first transition series of the Periodic Table (e.g., Ti, V, Cr, Mn, Fe, Co, Ni) as well as members in connecting groups, e.g., Cr, Mo, and W in Group VIa and Cu, Ag, and Au in Group Ib. These include metals which are tribologically difficult to machine and use (e.g., Ti), common elements in bearing steels (e.g., Fe, Cr), and metals useful in reducing friction or wear when applied as thin surface coatings (e.g., Ag, Au). The results of this comparison are interesting and surprising. They may add to our understanding of why some metals are very “difficult” in a tribological sense while others provide benefits in controlling friction and/or wear.