Stages in the Wear of a Prow-Forming Metal

Abstract

The stages in wear of a typical prow-forming metal, gold, were determined. They are: 1) prow formation at the initiation of sliding, characterized by a high wear rate, limited to the member having the larger surface involved in sliding (i.e., the flat in a rider-flat apparatus); 2) an intermediate stage of roughening and work hardening of the flat with reduction in its wear rate; and 3) a transition stage to the rider wear process. Soon after the transition, the flat gains mass, and the rider loses metal by transfer to the flat or as loose debris. The combined wear of both members for a given total sliding distance lessens with decreasing track length for unidirectional and reciprocating sliding—-both before and after the transition. Also, the number of passes to the transition is proportional to the length of track divided by the load. These phenomena originate in an increasing ratio of transfer to wear with decreasing track length, due to a diminished ability of wear debris to leave the zone of sliding. This increases the rate at which the track achieves the critical roughness and worked condition necessary for the transition.