Kinetics of Electrochemical Nanonucleation by Induced Codeposition of Iron Group Metals with Refractory Metals (W, Mo, Re)

It is shown that the earlier discovered features of the composition and properties of electrochemical coatings obtained by the induced codeposition from alloys of iron group metals (W, Mo, Re) such as nanocrystallinity (X-ray amorphism), macroscopic dimensional effects of microhardness and corrosion resistance, the effect of the volume current density on the properties and composition are a consequence of the fractality of the solutions of complexes (citrate, gluconate, etc.) in combination with the intensive interfacial exchange. In this case, the kinetics of nano-nucleation limits the size of the resulting alloy nucleus, as a result of which water molecules participate in the formation of coatings, leading to the incorporation of oxide-hydroxide inclusions into the solid phase and hydrogenation.

THE INFLUENCE OF GLUCONATE BATH PARAMETERS ON THE RATE OF ELECTRODEPOSITION AND MECHANICAL PROPERTIES OF Co–W COATINGS

The given study overview the results obtained for Co–W alloys electrodeposited from gluconate bath. Namely, the influence of different parameters (the concentration of the bath components, pH, temperature, cathodic current density, volume current density, hydrodynamic conditions, insoluble and soluble anodes) on the rate of electrodeposition and microhardness of the coatings has been investigated. The given research determine the conditions ensuring high deposition rate, microhardness and bath efficiency. It was shown, that the deposition rate, tungsten content and microhardness reach the maximum values at pH 6.5, regardless on the concentration of bath components. Also, it was detected the macroscopic size effect of microhardness, which is linked to the fact that for a fixed cathodic current density microhardness depends on volume current density. In addition, different anodes (Pt, graphite, W and Co–W) were investigated to reveal the anode influence on reaching the maximum values of the current efficiency and microhardness.