The Surface Layer States in Metallic Materials Subjected to Dry Sliding and Electric Current

Abstract

The structure and properties of surface layers of metallic materials undergoing structural-phase changes as a result of their contact interactions in the form of dry sliding friction on steel in combination with exposure to electric currents are investigated. This impact results in the formation of a composite surface layer whose structural constituents are the particles of FeO oxide, FCC- and BCC-iron, and quasi-amorphous initial material. Sliding of materials at the contact current density higher than 150 A/cm² gives rise to the formation of local, low-stability structures which, as a result of phase transformations, are observed as sectors of quasiliquid plastic flow on the sliding surface. It is shown that the average temperatures of the Cu – steel material contact do not exceed 300°С, i.e., none of the surface-layer constituents reaches its melting temperature. It is shown that quasi-liquid plastic flow favors stress relaxation and maintains the strength of the surface layer, which ensures its lower wear.