Research on the dynamic evolution of competitive and water-film-mediated wear mechanisms of the carbon strips in the pantograph-catenary system at low temperature

Abstract

To investigate the evolution of wear mechanisms in carbon strips at low temperature, this study conducted comparative friction tests on copper-impregnated carbon strips at room temperature (25 °C) and low temperature (-20 °C). To replicate operating conditions, the experiments were conducted on a high-speed electrical sliding wear tester, with a current of 200 A, a normal load of 100 N, and a sliding speed of 300 km/h. This study analyzed the dynamic evolution of wear rate, coefficients of friction, and arc discharge behavior of carbon strips. Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) were employed to observe the microstructure and elemental distribution patterns on worn surfaces. Results show that low temperature alters the competition between wear mechanisms and the evolution pathway of materials. Low temperature suppresses the oxidative wear, with the surface temperature of the contact pairs significantly decreasing. Additionally, a water film formed by frost melting on the contact surface serves as a critical interfacial medium, performing dual functions of lubrication and arc enhancement.EDS analysis revealed that the O/Cu atimic ratio at room temperature was higher than that at low temperature, confirming that low temperature suppresses copper oxidation. The study elucidated the wear mechanisms of current-carrying friction and wear of carbon strips from both thermal (temperature at thermal equilibrium of the contact interface) and electrical (current-carrying capacity of carbon strips) perspectives, providing a theoretical foundation for the operation and maintenance of the pantograph-catenary system in cold regions.