Paper 19: Unlubricated Sliding at High Speeds between Copper and Steel Surfaces

Abstract

Experiments are described in which stationary copper specimens are rubbed in a normal atmosphere against a rotating S62 steel disc under normal loads up to 4·5 lbf. The coefficient of friction is measured at sliding speeds of 93, 220, 328, and 490 ft/s using ⅛-in diameter specimens. Except at the lowest speed a gradual buildup of a continuous copper oxide layer on the disc track is observed with increasing normal load together with a corresponding decrease in the coefficient of friction. Having established an oxide layer on the track the coefficient of friction observed is low for all normal loads. The coefficient of friction is shown to decrease with normal load N and sliding speed U, to be a function of N^1/2U, and to depend on the state of the disc surface. Wear of -in diameter specimens is measured by weighing before and after a test. The wear rate is shown to decrease with sliding speed and increase with load, and for speeds of 220 and 328 ft/s to be a function of N/U. The wear rates measured at 93 ft/s are the same function of N/U for low values of N/U.