Wear Mechanisms in Dry Sliding Friction Tests of Copper Versus Steel

Dry sliding wear tests were performed using a ring-on-block configuration for copper sliding against steel. The wear mechanisms of this pair were investigated under different load ranges and sliding velocities. During the tests, the bulk temperature in the near-surface contact region was continuously recorded. The results of scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDS) and nanoindentation tests on the worn surfaces and the debris reveal a commanding role of the steel in the wear mechanisms of the pair. Additional tests of steel-steel pairs corroborate this assumption. It will be shown that the different wear mechanisms, which the steel experiences over the test range, markedly influence copper wear rates. Metallographic investigations on cross sections of copper samples show the formation of recrystallized layers on the worn surface at high sliding speeds. The onset of recrystallization is accompanied by extrusion of wear debris.