Analytical Estimation of the Melt-like Sublayer Thickness Within the Contact Zone Between M2 Steel and C45 Steel During Dry Sliding Under High-Density Alternating Electric Current

The development of new principles for controlling the technical systems requires the use of reliable actuators. A sliding steel/steel contact under a high-density electric current could serve as one of their elements. The search for the factors reducing the wear of the contacts is a subject of scientific and commercial interest. One such factor is the melting that occurs within a sliding steel/steel electrical contact space. The overall goal of this study is to describe the characteristics of an M2 steel/steel sliding electrical contact during the formation of a melt-like state in the contact zone. Dry sliding of M2 steel (sample) against C45 steel (counterbody) under an alternating electric current at a density higher than 100 A/cm2 is performed as a model experiment using the well-known “pin-on-ring” tribo-loading configuration. The formation of tribolayers on the sample and the counterbody is demonstrated using a scanning electron microscope and a MICRO MEASURE 3D-station non-contact device. According to the EDX analysis, the contact layers predominantly contain oxygen and iron. Two sectors with different morphological features are observed on the M2 steel sliding surface. A melt-like state is visible in one of the sectors. This state is assumed to form within a certain sublayer. A method for calculating this sublayer thickness is proposed. This thickness does not exceed 10 μm. The calculation model has revealed that the thickness of this sublayer depends mainly on the external impact power rather than on the atomic and phase composition of the tribolayer. An increase in the contact current density is consistent with an increase in the calculated thickness of this sublayer, an increase in the electrical conductivity of the contact, and a decrease in the coefficient of friction (COF). The proposed analysis of the obtained results could serve as a basis for broader generalizations.