| Zinc and zinc-tin alloys have excellent anti-corrosion properties and are of great significance in the field of corrosion prevention.Electrodeposition is a common method to obtain coatings for metals and alloys.In traditional aqueous solutions,electrodeposited zinc is inevitable because the potential of zinc is more negative than that of water;In addition,conventional electrodeposited zinc-tin alloys use toxic cyanide solutions.Deep eutectic solvent is known as a new green solvent,which has the advantages of wide electrochemical window,excellent electrical conductivity,simple synthesis,etc.,and is often used to electrodeposition metals and alloys.In this paper,choline chloride-urea deep eutectic solvent（ChCl-urea-ZnO）containing zinc oxide and choline chloride-ethylene glycol deep eutectic solvent（ChCl-EG-SnSO4-ZnSO4）containing SnSO4 and ZnSO4 were used as electrolytes to carry out experimental research on the preparation of Zn and Zn-Sn alloy coatings by electrodeposition.The effect of water on the electrodeposition of zinc in a simulated leachate（ChCl-urea-ZnO）with a deep eutectic solvent leaching zinc-containing soot was studied.The relationship between various thermodynamic and kinetic parameters and water content（0～24 vol%）was explored,and the morphology and phase composition of the coating were analyzed.The results show that with the increase of water content,the initial reduction potential of Zn2+shifts positively,and the peak current density increases.An increase in water content not only increases the diffusion coefficient,but also leads to an increase in the charge transfer coefficient.The standard rate constant first increases and then decreases with the increase of water content,and is the maximum when the water content is 7.5 vol%.In addition,the electrodeposition Zn in the ChCl-urea-ZnO system conforms to three-dimensional progressive nucleation.Zn is electrodeposited in the aqueous ChCl-urea-ZnO system,and Zn conforms to three-dimensional progressive nucleation before tm,and Zn after tm conforms to three-dimensional instantaneous nucleation.Adding water to ChCl-urea-ZnO can increase its nucleation rate,improve the smoothness and compactness of the coating,and the current efficiency first increases and then decreases with the increase of water content.ChCl-EG-SnSO4-ZnSO4 was used as the electrolyte to study the electrodeposition behavior of the electrodeposited Zn-Sn alloy.The electrochemical behavior of Zn,Sn and Zn-Sn alloys in this system was explored,Zn2+first formed the intermediate product Z,Z was reduced to Zn at about-1.1 V,Sn2+was reduced to Sn at about-0.38V,and the co-deposited nucleation of Zn and Sn was instantaneous nucleation.It was found that the electrodeposition parameters（temperature,deposition potential,concentration of ZnSO4 and SnSO4,and deposition coulomb number）had a significant effect on the coating composition,morphology,phase composition and anti-corrosion performance of Zn-Sn alloy.The results showed that at 70°C,-1.1 V,15 mmol·L-1SnSO4 and 65 mmol·L-1 ZnSO4,3 C·cm-2,electrodeposited coating corrosion current density is 4.79×10-6 A·cm-2.The electrodeposited Zn-Sn alloy coating in ChCl-EG DES was studied by the response surface method,and the optimal experimental conditions were found:temperature 70.18°C,potential-1.1 V,SnSO4 concentration10.75 mmol·L-1,ZnSO4 concentration 69.25 mmol·L-1,corresponding to a response value of 3.818×10-6 A·cm-2.Under the optimal experimental conditions,the effect of additive nicotinic acid on electrodeposition of Zn-Sn alloy was studied,and it was found that niacin added to an appropriate amount(8 mmol·L-1),the corrosion current density of Zn-Sn alloy plating obtained by electrodeposition is as low as 8.44×10-7A·cm-2. |
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