| DING Yunhu,LI Yuxin,HU Xialin,HE Ying,LIU Hongfang,DUAN Haitao.Effect of Plating Bath Composition on the Properties of Zn-Ni AlloyCoating in Alkaline Electrolysis System[J],54(4):130-142 |
| Effect of Plating Bath Composition on the Properties of Zn-Ni AlloyCoating in Alkaline Electrolysis System |
| Received:April 01, 2024 Revised:September 03, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2025.04.010 |
| KeyWord:Zn-Ni alloy alkaline electroplating coating thickness and nickel content corrosion resistance microstructure |
| Author | Institution |
| DING Yunhu |
China Academy of Machinery Wuhan Research Institute of Materials Protection Co., Ltd., Wuhan , China |
| LI Yuxin |
China Academy of Machinery Wuhan Research Institute of Materials Protection Co., Ltd., Wuhan , China |
| HU Xialin |
China Academy of Machinery Wuhan Research Institute of Materials Protection Co., Ltd., Wuhan , China |
| HE Ying |
School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan , China |
| LIU Hongfang |
School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan , China |
| DUAN Haitao |
China Academy of Machinery Wuhan Research Institute of Materials Protection Co., Ltd., Wuhan , China |
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| Abstract: |
| The Zn-Ni alloy process is an ideal protection technology for high-strength steel used in aviation field, and the Zn-Ni alloy coating has the characteristics of good corrosion resistance and low hydrogen embrittlement. However, in the Zn-Ni alloy process, the change of coordination agent concentration and solution service life have a great effect on the change of metal ion concentration and proportion in the plating solution during the actual deposition process, and the metal ion concentration and proportion of the plating solution have a great impact on the performance of the plating layer. In this experiment, the work aims to study the effect of a single parameter in an alkaline Zn-Ni alloy solution with complexing agent C as the main complexing agent for nickel ions on the performance of Zn-Ni alloy coatings prepared by electrodeposition on Q235 steel. Q235 steel of 20 cm×10 cm×1 mm (Hull Cell test) or 50 mm×100 mm×1 mm was used as the cathode, and then pre-treated, and nickel plate was used as the anode. When the cathode current density was 5 A/dm2 and the temperature was 25 ℃, the nickel ion content in the plating solution was between 1-2 g/L, the zinc ion content in the plating solution was between 6-10 g/L, and the complexing agent C content in the plating solution was between 60-160 mL/L. The sodium hydroxide content in the plating solution was between 80-160 g/L, and four groups of Zn-Ni alloy coatings under different conditions were prepared by electrodeposition on Q235 steel under control of single parameter changes. Then, the thickness and nickel content of the coatings were analyzed by X-ray fluorescence thickness gauge (BA-100), the electrochemical impedance and Tafel curve were determined by an electrochemical workstation (PARSTAT2273), the corrosion resistance of the Zn-Ni alloy coatings was characterized by the self-corrosion current density and charge transfer resistance, and the microscopic morphology of the Zn-Ni alloy coatings was observed by scanning electron microscope (JSM-6510LV). The experimental results showed that under other conditions, the nickel content of the coatings was directly proportional to the nickel ions and complexing agent C content in the plating solution, and inversely proportional to the zinc ions and sodium hydroxide content, and the nickel content in the coatings was much lower than the zinc content, which was an abnormal co-deposition in the alkaline Zn-Ni process system. The results of scanning electron microscopy and electrochemical test showed that when other conditions were constant, as the content of nickel ions and complexant C increased, the corrosion current density of the coating decreased, and the maximum and minimum values of the corrosion current density differed by an order of magnitude. In summary, in the alkaline Zn-Ni process of complexing agent C, the nickel content of the coating is relatively stable. The change of metal ions (zinc and nickel ions) in the plating solution has a great effect on the nickel content of the plating layer. When other conditions are constant, the nickel content of the plating layer can be stable at 12wt.%-15wt.% with the contents of nickel ions, zinc ions, complexing agent C and sodium hydroxide in the plating solution as 1-1.2 g/L, 8-9 g/L, 60-160 mL/L and 80-160 g/L respectively. The change of the single concentration of each component in the plating solution changes the nickel content and morphology of the coatings, which has an impact on the corrosion resistance of the coatings. When other conditions are constant, the content of nickel ions, zinc ions, complexing agent C and sodium hydroxide in the plating solution is 1.6 g/L, 7 g/L, 140 mL/L and 80 g/L, respectively, and the corrosion resistance of the plating layer is the best. The content of nickel ions, zinc ions, complexing agent C and sodium hydroxide in the plating solution will affect the nickel content in the plating layer to a certain extent, and then affect the microscopic morphology and corrosion resistance of the coatings. |
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