Research On Preparation And Tribological Properties Under Electric Current Of Friction Grounding Device Of High-speed Train

The tests prepare the graphite/copper composite material by the way of powdermetallurgy and study the influence of the Tin content on the mechanical properties ofcomposite materials, which simulated the working conditions of the rush and the trainaxle used in the electric train on the HST-100tribo-tester. Single-factor tests wereconducted to investigate the influence on current and velocity of the friction and wearproperties and current properties. With the help of SEM, Surface Plasmon ResonanceAnalyzer and EDS, the morphologies of worn surface of pin were examined in order tostudy the tribological mechanism under different condition.The results show that, because of solid solution strengthening effect, the hardnessof composite material is improved, but the conductivity of the composite materialreduces due to the scattering of electrons in the crystal lattice distortion，and thedensity of composite material reduces.With the increasing of current, the surface of the composite material softening,the force between micro-convex decreases, so the friction coefficient decreases. Andsoftening is easy to cause adhesive, so current-carrying efficiency decreases and arcrate rises. Wear rate increases with the increasing of arc rate. With the increasing ofTin content, the resistance is bigger, the composite material produces more heat whenthe current is equal, the friction coefficient is small because of softening. Wear ratereduces with the decreasing of Tin content when the current is smaller, but wear rateincreases quickly due to erosion when the current exceeds60A.High tin material is notsuitable for friction with large current.Friction coefficient and wear rate increase with the increasing of velocity. Thecontact condition of pin and plate deteriorate, current-carrying efficiency decreases,the surface roughness because of arc, and friction coefficient increases. Arc ablation ismore serious than mechanical wear, wear rate increases with the increasing of velocity. Friction coefficient and wear rate are smaller when the velocity is smaller, because theoxidation film is formed easily when the Tim content is higher. Wear rate increaseswhen the velocity exceeds20m/s. High tin material is not suitable for friction withhigh velocity.With the increasing of current and speed, the wear mechanism changes frommechanical wear gradually to electrical wear, which is serious.