Electrochemical Deposition of Zn-Cu Alloy on St37 in Choline Chloride-Ethylene Glycol Electrolyte

Document Type : Original Article

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Advanced Materials Research Institute, Faculty of Materials Engineering, Sahand University of Technology, Tabriz, Iran.

Abstract

Aqueous electrolytes used in electrochemical deposition processes of zinc and its alloys have inherent drawbacks, such as corrosion of metal substrates, undesirable hydrogen gas evolution at high currents, and limited operating voltage. In this research, the electrochemical deposition of Zn-Cu alloy on St37 substrate was performed using choline chloride-ethylene glycol as a deep eutectic solvent (DES). The main objective of this study was to investigate the effect of the copper to zinc molar ratio in the electrolyte (1 to 10, 1 to 5, and 1 to 3) and current density (1 and 5 mA/(〖cm〗^2 )) on the morphology, chemical composition, and corrosion resistance of the coating. For this purpose, Field Emission Scanning Electron Microscopy (FESEM), X-ray Diffraction (XRD), Energy Dispersive X-ray Spectroscopy (EDS), and polarization testing were used. The results showed that at a copper to zinc molar ratio of 1 to 3 and a current density of 1 mA/(〖cm〗^2 ), only copper was deposited, but by reducing the copper to zinc ratio to 1 to 10, a layer containing 50 at. % zinc was obtained. Furthermore, by increasing the current density from 1 to 5 mA/(〖cm〗^2 ), the percentage of zinc in the zinc-copper alloy layer with a thickness of 3.61 μm increased to 65 at. %. The highest layer thickness, at a current density of 5 mA/(〖cm〗^2 ) and a copper to zinc ratio of 1 to 3, was approximately 16 μm, containing 47 and 53 at. % of zinc and copper, respectively. Also, this formed layer exhibited the lowest corrosion current density (approximately 4.6952 μA/(〖cm〗^2 )).

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Applied Chemistry Today
Volume 20, Issue 76
September 2025
Pages 9-30

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