Anodic Dissolution of Surface Layers as a Method of Increasing the Microhardness of Coatings by Alloys of the Iron Group Metals with Tungsten Obtained by Induced Co-Deposition

Abstract

UDC 544.65+621.357

https://doi.org/10.52577/eom.2023.59.3.01

It is shown that the macroscopic dimensional effect of the composition and properties (microhardness and corrosion resistance) of coatings obtained by induced co-deposition of the iron group metals with tungsten (the effect of the surface area of electrodeposition on the composition and properties) due to the presence of oxide-hydroxide layers in the surface layer, as well as hydrogenation, is a special case of effects of this kind; this, in turn, requires a constant volumetric current density (mA/L) during electrodeposition. It has been established, using examples of electrodeposition of Fe-W and Co-W alloys from a citrate bath, that a change in the volumetric current density at a fixed electrodeposition current density leads to a change in the potential, the current output, and in the composition of the alloy in the coating. Anodic dissolution of the modified surface layer increases the microhardness, but does not eliminate the effect of dependence of the composition and properties of coatings on the electrodeposition surface area.

Keywords: induced co-deposition, electrochemical production of alloys, alloys of iron group metals with tungsten, dimensional effects in electrochemistry, citrate electrolyte, scale transfer