CHARACTERIZATION OF WEAR SCAR SURFACES USING COMBINED 3-DIMENSIONAL TOPOGRAPHIC ANALYSIS AND CONTACT RESISTANCE MEASUREMENTS

In this paper, a technique for the quantitative characterization of we ar scar surfaces, using combined three-dimensional topographical analy sis and contact resistance measurements, is introduced. Parameters for the characterization of wear surfaces, developed during sliding of pi n-on-disk specimens in oxygen at high temperature, such as wear volume , roughness, average wear depth on the disk specimen, surface coverage by wear-protective oxide layers and their distributions over the wear surface, are presented and calculated. Such analyses provide more eff ective data for the analysis of wear processes and wear mechanisms. Th is method has been applied to the analysis of dry reciprocating slidin g wear of a nickel-base alloy, N80A, at temperatures to 600 degrees C. It was found that there was usually a difference between the wear rat es of the pin and the disk. This difference increased with increase in temperature, the wear of the pin being much less than that of the dis k at the higher temperatures. Although the total wear of both the pin and the disk decreased considerably with increase in temperature, the damage to the disk, judged by the wear depth of the scar, was much hig her at elevated temperatures than at low temperatures. The roughnesses of the wear surfaces generally increased with increase in temperature . Less than 50% coverage of the scar surfaces by wear-protective oxide layers was sufficient for the severe-to-mild wear transition. However , the distribution of the wear-protective layers over the wear surface s was non-uniform. Most of them were concentrated near the centre of t he scar, along the sliding direction, under the present conditions. Th ese features of the wear scar surfaces were mainly related to the adhe sion and compaction of wear debris particles onto the wear surfaces, l eading to development of the wear-protective layers at the various tem peratures. (C) 1997 Elsevier Science Ltd.