Electrodeposition of composition controllable Zn Ni coating from water modified deep eutectic solvent

Electrodeposition of ZnNi Alloys from Choline Chloride/Ethylene Glycol Deep Eutectic Solvent and Pure Ethylene Glycol for Corrosion Protection

“…For these reasons, organic solutions were considered as a possible substitute for the traditional aqueous ones, showing higher control on the alloy composition. 7 − 11 In the framework of nonaqueous solutions, choline chloride based deep eutectic solvents (DESs) 12 are one of the most investigated systems alternatively to traditional plating, 13 − 15 counting several efforts toward making them appealing for industrial applications. 16 − 24 Their relative low cost, sustainability, and physicochemical properties have indeed attracted the attention of researchers aiming to improve the coating properties and/or the process efficiency with respect to water based ones, as in the case of Zn 25 − 31 and Zn based alloys.…”

“…Conversely, Zn-rich coatings were obtained by tailoring the water content in the 1ChCl:2U solution, shifting the compositional window from 50–100% wt to 5–40% wt of nickel. 11 The corrosion properties of the coating were investigated at different compositions, showing higher corrosion potentials and lower corrosion currents progressively increasing the nickel content. Ethylene glycol based DES (1ChCl:2EG), on the other hand, was first investigated for the ZnNi alloy electrodeposition by Pereira et al, 8 focusing on the effect of amines on the morphology of zinc-rich films having 5–7% wt Ni.…”

“…For these reasons, organic solutions were considered as a possible substitute for the traditional aqueous ones, showing higher control on the alloy composition. − In the framework of nonaqueous solutions, choline chloride based deep eutectic solvents (DESs) are one of the most investigated systems alternatively to traditional plating, − counting several efforts toward making them appealing for industrial applications. − Their relative low cost, sustainability, and physicochemical properties have indeed attracted the attention of researchers aiming to improve the coating properties and/or the process efficiency with respect to water based ones, as in the case of Zn − and Zn based alloys. − The wider electrochemical window of these DESs (2.1–2.2 V for choline chloride/urea 1:2 mixtures; 1.7–2.1 V for choline chloride/ethylene glycol 1:2 mixtures) makes them suitable for the plating of metals with low reduction potential by limiting the onset of secondary reactions such as hydrogen evolution, affecting both coating and substrate properties. − In turn, DESs are also characterized by significant drawbacks. In particular, their comparatively high viscosity reduces mass transfer of electroactive species .…”

“…The electrodeposition of Zn–Ni alloys, in the framework of DES, has been investigated mostly from the choline chloride/urea system (1ChCl:2U). ,− The study of Yang et al focused on the synthesis and characterization of Ni-rich alloys (50–100 % wt Ni). The zinc content progressively increased with the cathodic potential applied, associated with the formation of cracks in the film.…”

“…Fashu et al , further examined this system by exploring the effect of the different experimental parameters and additives (EDTA and NH 4 Cl) aiming at the formation of a smooth and crack-free Ni-rich film. Conversely, Zn-rich coatings were obtained by tailoring the water content in the 1ChCl:2U solution, shifting the compositional window from 50–100% wt to 5–40% wt of nickel . The corrosion properties of the coating were investigated at different compositions, showing higher corrosion potentials and lower corrosion currents progressively increasing the nickel content.…”