Contact characteristics of C235 steel in dry sliding against C45 steel under high-density alternating current at different transformation coefficients of supply transformer

The authors studied the tribotechnical behavior of C235 steel under conditions of dry sliding electrical contact with a current density of more than 100 A/cm 2 at different transformation coefficients of the supply transformer. A decrease in the transformation coefficient leads to a decrease in the wear resistance and electrical conductivity of the contact. Metallographic methods revealed the formation of transfer layers on the contact surfaces. Thickness of the transfer layers does not exceed 20 μm. Morphological patterns of worn contact surfaces on the scale of the nominal (geometric) contact area consist of two sectors, where one sector has signs of melting. X -ray phase analysis has shown that the transfer layers contain more than 70 vol. % FeO. That is why the transfer layers could be represented as a quasi-dielectric medium, where FeO acts as a dielectric. The authors assume that strong self-induction pulses occur in the contact zone, which cause high-density displacement currents. These currents act directly on FeO ions and convert them into a melt. These concepts allow us to assert that the melt consists of atoms or ions of iron and oxygen. A decrease in the transformation coefficient (that is, an increase in the inductance of the secondary winding of the supply transformer) causes an increase in self-induction pulses and displacement currents, which leads to an increase in the amount of FeO melt, its easy removal from the contact area, and a corresponding decrease in the wear resistance and electrical conductivity of the contact. The data obtained can serve as guidelines when choosing wear-resistant materials for high-current sliding contact and, in particular, when defining its design.