Tribological Characteristics and Corrosion Resistance of Coatings Obtained by Electrospark Alloying, Pulsed Cathodic Arc Evaporation, and Hybrid Technology Using TiCNiCr and TiCNiCr–Dy2O3 Electrodes

Abstract

Single- and double-layer coatings on 40Cr steel substrates have been obtained by electrospark alloying (ESA) and a combination of ESA technology and pulsed cathodic arc evaporation (PCAE) using TiCNiCr and TiCNiCr–Dy2O3 electrodes. The electrodes are obtained by powder metallurgy. The structure and elemental and phase composition of the electrodes and coatings are studied using scanning electron microscopy, energy dispersive spectroscopy, and X-ray phase analysis. The tribological properties of the coatings are determined as a result of tests according to the pin-on-disk scheme in contact with the Al2O3 counterbody at loads of 1, 5, and 10 N. The temperature during the tests is T = 20°C. The potential and current density of corrosion are determined using a three-electrode cell with a VoltaLab 50 potentiostat. The results show that the electrodes consist of TiC grains of 12 μm; a solid solution of Ni in Cr; and, in the case of a doped electrode, Dy2O3 up to 5 μm in size. ESA coatings have a low-defect fine-grained structure consisting of regions of a solid solution of Ni and Cr in Fe and titanium carbide grains with a maximum size of 0.3 μm. Coatings with the addition of Dy2O3 have a lower coefficient of friction at loads of 1, 5, and 10 N. All coatings in 1 N H2SO4 are in a stable passive state and have high corrosion resistance: the corrosion current density of the coatings is at least 4 times lower than the values obtained for a 40Cr steel substrate.