Arc Erosion Characteristics of Cu-Impregnated Carbon Materials Used for Current Collection in High-Speed Railways

Currently, great attention has been paid to the fast development of high-speed railways all over the world. With an increment of running speed, pantograph arcing has become a significant issue, which can threaten the lifespan and service performance of pantograph strip materials severely. Cu-impregnated carbon strip is one of the most widely used strip materials in high-speed railways, while its arc erosion characteristics and mechanisms are still in absence. In this paper, the arc erosion characteristics of Cu-impregnated carbon materials were experimentally studied. The variations in voltage waveforms between electrodes with time were recorded, and the evolution of the temperature distribution of strip was obtained by a thermal infrared imager. The arc erosion surface was examined using a digital camera, a scanning electron microscopy, and energy dispersive X-ray spectroscopy to assess the macroscopic and microscopic morphologies, as well as elemental distributions in or around the arc erosion crater. An interesting arc crater-centered multicolored subarea on the strip surface was found, which was explained from the aspects of the effect of arc-induced temperature and formation of copper oxide film. The arc erosion crater consisted of several overlapped erosion pits, and the mechanism of the pits was understood from the unique microstructure and physical properties of carbon phase and copper phase in the materials. Finally, the formation of spherical copper particles and cracks was illustrated, and their influences on the sliding wear and friction process were discussed.