Study on the Damage Mechanism of an H62-Cu/7075-Al Tribo-Pair Under the Influences of Current Direction and Density

In the present study, we used 7075 Al-H62 Cu and H62 Cu-7075 Al pairs to study the effects of current density and direction on their tribological properties and on the damage caused by the current-carrying friction and wear. We found that, when the current density increased from 0 A/mm2 to 79.61 A/mm2, the coefficients of friction for both pairs decreased. Results obtained after wear indicate that the current direction influences the electromigration between the two tracks, leading to different kinds of damage on the worn surface. In the case of the 7075 Al-H62 Cu pair, damage mainly involved mechanical wear at low current densities. As the current density increased, electro-erosion damage gradually became more dominant. Under the action of a large electric arc, the material surface was severely eroded, and a dense oxide film formed on the material contact surface, ultimately leading to the failure of electrical conduction between the materials. In the case of the H62 Cu-7075 Al pair, damage mainly involved mechanical wear. A layer of copper film was found on the surface of the worn aluminum pin, which caused its mass to be greater than it was before wear.