Generation conditions of rolling current-carrying associated arc on Cu-Cu pairs and the surface damage mechanisms

This study employs copper (Cu)-Cu rolling pairs to investigate the failure characteristics and surface damage mechanism of current-carrying tribological contacts under various conditions (contact load P = 40-180 N, rotation speed v = 4-600 rpm, and current I = 0-2.5 A). Based on synchronous current curves and video observations, the severe current fluctuations caused by the electric arc can be considered a criterion for the failure of rolling electrical contacts. Surface damage assessment through scanning electron microscopy, X-ray photoelectron spectroscopy, and atomic force microscopy (AFM), reveal ablation pits, oxidation, and roughening as primary manifestations of electrical damage. Post -rolling, the Cu on the surface was oxidized to copper (II) oxide. As the degree of oxidation increased, the conductive area in the AFM current map decreased significantly at a sample bias voltage of 1.5 V. Notably, arc generation was subjected to the triple acceleration of the contact load, rotation speed, and current. A back propagation (BP) neural network model was established to predict the running cycles before arc generation. Based on independent validation experiments under P = 120 N, I = 1.0 A, v = 400, and 600 rpm, the average prediction error of the proposed BP neural network model was 8.13 %. The results of this study facilitate the understanding of failure mechanism and predicting life cycles of rolling electrical contacts.