Distribution of Oxygen in Surface Layer of Steel Counterbody from С45 Steel under Friction Conditions without Lubricant under Action of High-Density Electric Current

The aim of the work is to study the distribution of oxygen in the contact layer of steel 45 during pin-on-ring dry friction against C235 steel under high-density electric current (> 100 A/cm²).

The formation of a transfer layer on the contact surface of the counterbody and the formation of a melt on the contact surface of the transfer layer were shown by the electron microscopy method. The melt has weak signs of adhesive interaction, which is an indicator of high melt viscosity. X-ray spectral microanalysis of the contact surface of the transfer layer showed an oxygen content of 30 at. %, which serves as an indicator of FeO formation. The oxygen concentration corresponded to a concentration of about 60 vol. % FeO. The oxygen concentration in the cross-section of the transfer layer at a distance of 3 μm from the contact surface was about 10 at. % that corresponds to about 20 vol. % FeO. The X-ray phase analysis method established the predominance of FeO and α-Fe in the contact surface of the transfer layer of C45 steel, i. e. about 90 vol. % FeO. These data indirectly prove the existence of a FeO concentration gradient directed into the depth of the transfer layer and allow us to state that the melt consists of neutral atoms or ions of iron and oxygen.

An increase in the current density in the contact leads to an increase in the electrical conductivity of the contact and to a decrease in the friction coefficient. This allows us to assume an increase in the amount of melt in the contact space with an increase in the current density. An increase in the current density leads also to an increase in the sliding stage (“slip”) during sliding in the stick–slip mode and to a decrease in the friction coefficient. The obtained data can serve as a guideline in the design of current-collecting friction units for powerful electric motors and generators.

1. Kragelsky I.V., Dobychin M.N., and Komba-lov V.S. Friction and Wear Calculation Methods. — New York: Pergamon Press. — 1982

2. Sosnovskiy L.A. Tribo-Fatigue: Wear-Fatigue Damage and Its Prediction. — Verlag, Berlin, Hei-delberg: Springer. — 2005

3. Aleutdinova M.I., Fadin V.V., Kolubaev A.V. On wear of metal materials loaded with sliding friction and high-density electric current // Letters on Mate-rials. — 2014 (4), no. 3, 149—152. https://doi.org/10.22226/2410-3535-2014-3-149-152 (in Russian)

4. Fadin V.V., Aleutdinova M.I., Rubtsov V.Ye., and Aleutdinova V.A. Structure and Worn Surface Morphology on Copper Containing Composites under Dry Sliding with High Contact Current Densi-ty // Key Eng. Mater. — 2016 (712), 137—142. DOI: 10.4028/wwwscientific.net/KEM.712.137

5. Aleutdinova M.I. and Fadin V.V. Structure of the Contact Layers of Steel and Their Deterioration in Dry Sliding Against Steel under High-Density Elec-tric Currents at Different Turn Ratios of a Supply Transformer // Rus. Phys. J. — 2024 (67), no. 1, 1—8. DOI 10.1007/s11182-024-03081-9.

6. Waseda Y., Matsubara E., and Shinoda K. X-Ray Diffraction Crystallography. Introduction, Examp-les and Solved Problems. — London, New York: Springer Heidelberg Dordrecht, Springer-Verlag Ber-lin Heidelberg. — 2011. DOI: 10.1007/978-3-642-16635-8

7. Yin Cun-hong, Liang Yi-long, Liang Yu., Li W., and Yang M. Formation of a Self-Lubricating Lay-er by Oxidation and Solid-State Amorphization of Nano-Lamellar Microstructures during Dry Sliding Wear Tests // Acta Materialia. — 2019 (166), 208—220. https://doi.org/10.1016/j.actamat.2018.12.049

8. Wang S.Q., Wei M.X., and Zhao Y.T. Effects of the Tribo-Oxide and Matrix on Dry Sliding Wear Characteristics and Mechanisms of a Cast Steel // Wear. — 2010 (269), 424—434. https://doi.org/10.1016/j.wear.2010.04.028

9. Kato H. Effects of Supply of Fine Oxide Particles onto Rubbing Steel Surfaces on Severe-Mild Wear Transition and Oxide Film Formation // Tribol. Int. — 2008 (41), 735. https://doi.org/10.1016/j.triboint.2008.01.001

10. Mansori M.El., Paulmier D., Ginsztler J., and Hor¬vath M. Lubrication Mechanisms of a Sliding Contact by Simultaneous Action of Electric Current and Mag¬netic Field // Wear. — 1999 (225–229), 1011—1016. https://doi.org/10.1016/S0043-1648(99)00070-8

11. Zhao H., Feng Y., Zhou Z., Qian G., Zhang J., Huang X., and Zhang X. Effect of Electrical Current Density, Apparent Contact Pressure, and Sliding Velocity on the Electrical Sliding Wear Behavior of Cu–Ti3AlC2 Composites // Wear. — 2020 (444–445), 203156. https://doi.org/10.1016/j.wear.2019.203156

12. Ferreira J., Farias A., Leonardi F., Bordinas-si Ed.C., Bortolussi R., and Delijaicov S. Dataset on Critical Angular Clamping Speeds of Fasteners // Data in Brief. — 2024 (52), 110022. https://doi.org/10.1016/j.dib.2023.110022

13. Zhang Ch., Keten S., Derome D., and Carmeliet J. Hydrogen Bonds Dominated Frictional Stick-Slip of Cellulose Nanocrystals // Carbohydrate Poly-mers. — 2021 (258), 117682. https://doi.org/10.1016/j.carbpol.2021.117682

14. Mei G., Fu W., Chen G., Zhang W. Effect of High-Density Current on the Wear of Carbon Sliders Against Cu–Ag Wires // Wear. — 2020 (452–453), 203275. https://doi.org/10.1016/j.wear.2020.203275