Features of Electrospark Coatings Formation on a Chromium Substrate Using Ceramic ZrSi2-MoSi2-ZrB2 and HfSi2-MoSi2-HfB2 Electrodes

Abstract

The work is devoted to the study of the features of mass transfer, structure and properties of electrospark coatings on substrates made of the chromium alloy grade VKh1-17A using SHS-electrode ceramics of the compositions ZrSi2-MoSi2-ZrB2 and HfSi2-MoSi2-HfB2. The coatings were studied using X-ray diffraction, scanning electron microscopy, energy-dispersive analysis, and tribological tests using the “pin-on-disk”; nanoindentation was also carried out. The kinetics of the mass transfer and heat resistance of coatings were determined by the gravimetric method. In accordance with the Palatnik criterion, the formation of coatings occured in the form of an alloy of an anode (electrode) and a cathode (substrate) materials, which ensures high adhesion of the surface layer. The maximum weight gain on the cathode was observed after the first minute of treatment, and subsequently a decrease in the mass of the cathode was noted. As a result of electrospark deposition, coatings with 100% continuity and a thickness of 10–20 µm were deposited on the surface of the chrome alloy VKh1-17A. Zirconium-containing coatings are characterized by a hardness of 18.2 GPa and an elastic modulus of 274 GPa, and coatings obtained using the HfSi2-MoSi2-HfB2 electrode were characterized by a hardness of 16.9 GPa and an elastic modulus of 332 GPa. The use of SHS-electrodes made it possible to increase the hardness of the surface layer of the chromium alloy by 4 times, wear resistance by 1.5 times, and oxidation resistance by 1.6 times at t 1000 °C for 30 hours of testing.