| Copper-zinc alloy coating is an ideal surface decoration material due to its bright colors,good corrosion resistance,low cost,and good machining performance.?n this paper,a stable and environmentally friendly copper-zinc alloy electroplating process with controllable composition,good coating quality and stable environment was constructed to optimize and improve the current key problems such as high toxicity of electrolyte or easy hydrogen evolution and hydrogen embrittlement.Building a preparation process of copper-zinc alloy plating based on eutectic solvent(DES)system,and further studied the influence of some process parameters on the copper-zinc alloy coating.This study provides a theoretical basis for the environmental protection,controllable composition,concise and efficient process development of copper-zinc alloy electroplating.First,electrodeposition of copper-zinc alloy coatings in choline chloride-urea deep eutectic solvent containing zinc oxide(Cu2O)and copper cuprous oxide(ZnO),using nickel as substrate,was studied.The electrochemical behavior of Cu(?)and Zn(?)was studied by cyclic voltammetry curve and linear voltammetry curve,found that copper is easier to precipitate in DES than zinc;By fitting the linear voltammetry curve,the results show that the content of copper and zinc in the coating calculated theoretically is basically consistent with the content of copper and zinc in the coating obtained by electrodeposition with constant potential.The effects of the deposition potential on the composition and morphology of the coating were also studied.The results showed that when the deposition potential was increased from-0.85 V(vs.Ag+/Ag)to-1.3 V(vs.Ag+/Ag),the Zn content in the alloy coating increased from 0at%to 76.29 at%.When the deposition potential is in the range of-1.10 V to-1.15 V,the Zn content is 12.5 at%to 20.81 at%.The coating is flat and dense,and the color is golden,which meets the requirements of imitation gold plating.?n addition,the imitation of gold electroplating in choline chloride-urea(ChCl-urea)deep eutectic solvent containing copper pentahydrate sulfate(CuSO4·5H2O)and zinc heptahydrate sulfate(ZnSO4·7H2O)with nickel-plated iron sheet as the substrate was studied.Through the test of the rotating disk electrode,the diffusion coefficients of Cu(?)and Zn(?)were calculated as follows:4.787x10-6cm2/s and 3.455x10-7 cm2/s.The influence of different concentrations of CuSO4·5H2O or ZnSO4·7H2O on the electrochemical behavior of Cu(?)or Zn(?)was studied by cyclic voltammetry curve and linear voltammetry curve.?t was found that the oxidation and reduction potentials of Cu(?)and Zn(?)on the glass carbon electrode and nickel electrode were positively shifted with the increase of CuSO 4·5H2O or ZnSO4·7H2O concentration.?n addition,the effects of different CuSO4·5H2O:ZnSO4·7H2O ratios,deposition potentials and deposition coulombs on the phase structure,microstructure and apparent morphology of the coatings were studied.The optimum process parameters of imitation gold plating in the system of ChCl-urea deep eutectic solvent containing CuSO4·5H2O and ZnSO4·7H2O were determined,that is,the electrolyte temperature was 70?,The proportion of the amount added CuSO4·5H2O to ZnSO4·7H2O was 7:3,the deposition potential was-1.6v,and the deposition coulomb was 2C.At this time,the coating had good luster,flat density,fine particles and uniform distribution.Compared with the ChCl-urea-Cu2O-ZnO,the ChCl-urea-CuSO4·5H2O-ZnSO4·7H2O was used to imitation gold plating had lower cost and shorter deposition time. |
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