Macroscopic Dimensional Effect of the Composition and Properties of Coatings With Alloys of Metals of the Iron-Tungsten Group During Induced Co-Deposition: Mechanism of Formation and Consequences

Abstract

Using the example of obtaining Co-W alloys it is shown that the observed features of the induced co-deposition, including the macroscopic dimensional effect of composition and properties, as well as nanocrystallinity, are a consequence of the fact that the inducing agent (a metal-precipitator complex) is a polymer complex with a high molecular weight. Under conditions with a high current load on the electrolyte, water molecules participate in the electrode process. This leads to the formation of the surface oxide-hydroxide layers and hydrogenation, as well as to an increase in the concentration of tungsten in the alloy due to a “side” reaction of hydrogen release, alkalinization and polymerization of the inducing agent. At a large-scale transfer from laboratory tests to industrial technology, along with maintaining the usual electrochemical parameters, the presence of a macroscopic dimensional effect (dependence of composition and properties on the surface area of electrodeposition) requires to maintain a constant current load on the electrolyte (volumetric current density).