ELECTROCHEMICAL DEPOSITION OF ZINC-BASED ALLOYS WITH LOW-MELTING METALS
Electrochemically alloying zinc with other metals is an efficient method of improving the anti-corrosion and other operational properties of electroplates. For the electrodeposition of corrosion-resistant coatings using zinc alloys with copper, antimony, cobalt, manganese, and lead, complex electrolytes based on Trilon B were developed. Trilonate electrolyte solutions are designed to replace toxic cyanide electrolytes used in industry. Disodium salt of ethylenediaminetetraacetic acid (Trilon B) forms with these metals water-soluble complexes and has surface-active properties, which contributes to producing a high-quality deposit. These electrolytes are characterized by high scattering capacity and performance and by the low level of internal stresses. The electrolytes developed are stable in operation and regenerate easily. We have identified the electrodeposition modes, as well as the compositions of our electrolytes. Within the density range from 1.0 through 2.0 A/dm2, dense, smooth, and semigloss coatings were obtained. It is shown that, in depositing zinc alloys with low-melting metals, deposits are formed that consist of crystallites having visible growth steps. Where zinc is introduced into a crystalline lattice, alloying components, such as copper, antimony, cobalt, etc., the nature of deposit morphology does not change, while the sizes of crystallites decrease, and the density of the growth steps increases on the crystal faces, the surficial relief of deposits become smoother, and the crystallites take on a prolate form. The coatings obtained are characterized by finely-crystalline structure, metallic gloss, and high values of corrosion resistance.