Influence of Interface Temperature on the Electric Contact Characteristics of a C-Cu Sliding System

Electrical contact resistance (ECR) and discharge are the key parameters of electrical contact performance for carbon-copper (C-Cu) contacts in the pantograph-contact line system. The change in physical and chemical properties of the C-Cu interface caused by interface temperature is the main reason for the variation in ECR and discharge. In this paper, an electric contact test platform based on interface temperature control was established. The influence of interface temperature on ECR and the discharge characteristics under different current amplitudes were studied. There are opposite trends in the change in ECR and the discharge characteristics with interface temperature under different currents, which results from the competition between interface oxidation and a softening of the contact spots caused by high temperature. The trend of interface oxidation with temperature was analyzed via the quantitative analysis of the composition and content of the oxides at the C-Cu contact interface and is discussed here. The relationship between interface oxidation, ECR, and discharge characteristics was studied. Furthermore, a finite element simulation model was established for estimating the temperature distribution throughout the C-Cu contact spots. The competitive process of the softening and oxidation of the contact spots at different temperatures and currents was analyzed, and the variation mechanism of the ECR and discharge characteristics with interface temperature was studied.