Frictional Properties of Metallic Films

Abstract

EXPERIMENTS, to be described elsewhere, in which the electromotive force generated by a loaded rotating steel ball in frictional contact with a metal block was measured, showed that the steel ball tended to pick up metal from the flat surface, and that metallic films wiped out on metal surfaces by hand affected both the magnitude of the electromotive force and the size of the final wear impression. Films of tin, copper, lead and zinc wiped out on Timken test blocks reduced the electromotive force in this order of merit when no oil had been applied to the contact. On the other hand, a film of tin rubbed on to the flat surface of a hardened steel roller led to an increase in both the electromotive force and the diameter of the final wear impression, and a film of lead rubbed on to a block of copper had a similar effect.