Influence of Electric Current on the Wear Topography of Electrical Contact Surfaces

Wind pitch slip ring consists of several circuits applied with changing electric current, which makes the wear mechanism extremely complicated. The aim of this paper is to study the influence of electric current on the wear behavior of friction pair using a ball-on-disc tribometer. The wear test was carried out with normal loads of 10 N and 15 N and applied electrical current ranging from 0.5 to 20 A. Wear topographies without electric current, with small (0.5-5 A) and large (5-20 A) electric current, were analyzed. The characteristic parameters (surface roughness, wear volume, and multifractal parameters) were used to comprehensively characterize the wear topography. The results indicate that the characteristic parameters of topography without current are the smallest. The main wear mechanism of friction pair without current is adhesion wear. The characteristic parameters fluctuate in a large range for the small current. The main wear mechanism of ball sample is adhesion wear with slightly arc ablation, but that of the disc sample is adhesion wear. The characteristic parameters increase with the electric current for the large current. The main wear mechanism of the ball sample is the interaction of adhesion wear and arc ablation, but that of disc sample is adhesion wear with slightly arc ablation. The electric current will aggravate the wear of friction pair and increase the singularity and complexity of the surface. The results are of great significance for guiding anti-wear design of wind pitch slip ring.