Failure analysis of the pure carbon strip affected by dynamic contact force during current-carrying sliding

The pure carbon strip is widely used in high-speed Electro Mechanical Units (EMUs) transit. Dynamic contact between the pantograph and the catenary produces internal cracks in the pure carbon strip, which results in the break of the pantograph and interruption of power transmission. The tribological properties and failure mechanism of the pure carbon strip is studied in this paper. The current-carrying tribology experiments were carried out on a flexible loading test rig. It is found that the dynamic contact in pantograph/catenary system produces regular influence on arc discharge and current transmission. The cracks and arc erosion are the most important failure mechanisms subjected to the periodic vertical contact force. The carbon fibers in the strip became orderly arranged honeycomb-structures after oxidation and sublimation. These honeycombstructures distributed nearby the pores and induced the initiation and propagation of cracks. Therefore, preparing high-strength carbon fibers and eliminating the combination gap between the carbon fibers and the carbon matrix are recommended to prevent the failure of pure carbon strip. Results in this paper are expected to provide data support for the failure analysis and manufacturing technology to the pure carbon strip, as well as providing theoretical supports to the locomotives in service.