Studies on the Bright Zinc-Nickel Alloy Palting in Alkaline Baths

Authors

Jiale Cai, Dept. of Chem., Xiamen Univ., Xiamen 361005
Shaomin Zhou, Dept. of Chem., Xiamen Univ., Xiamen 361005

Corresponding Author

Jiale Cai

Abstract

The electrochemical properties of the Zn-Ni plating baths and the structure andperformance of the obtained deposits were investigated. The results show that the nickel content of theobtained deposits is incereased with decreasing of Zn²⁺/Ni²⁺ ratio in the baths and with increasing of cathodic current density; The cathode current efficiency is increased with increasing of Zn[Ⅱ] content in the bath and with decreasing of cathodic current density. The ZN-11 additive used is thereaction product of heterocyclic compound and polyamines with epichlorohydrin, it has a higheradsorptivity on Hg-electrode at potential between -0.16～-1.68 V (vs. Hg/HgO, 1 mol·L^-1 KOH). It is found that zinc and nickel are codeposited anomalously due to the inhibition effect of ZN-11 additive on nickel deposition and the catalytic effect of the used complexing agent on zinc deposition. The results of X-ray diffraction analysis show that zinc-nickel alloy deposits with nickel content>10.6 wt% possess γ phase alone with preferred orientation of (330)+(411) of complex cubic. The zinc-nickel alloy deposits are bright with hard ness 220 to 270 Hv. The corrcoion experimence in5% NaCl solution shows that zinc-nickel alloy deposit with nickel content about 13 wt% behaves maximum protection to steel. The zinc-nickel alloy deposit with nickel content<10.6 wt% behaves anodic protection to steel, and with nickel content in the range of 10.6～14.5 wt% behaves mixedprotection of anodic and cathdic. On the base of the conclusions obtained above,a new technology of alkaline bright zinc-nickel alloy plating has been suggested. The optimum bath composition is found to be 4 to 10 g·L^-1 of ZnO, 70 to 120 g·L^-1 of NaOH, 4 to 15 mL·L^-1 Ni complexing compound, 0.05 to 0.3 g·L^-1 ofaromatic aldehyde and 0.5 to 3 mL·L^-1 ZN-11 additive, Zn²⁺/Ni²⁺ ratio (wt.) is 4 to 10. The bath operates in 15～65 ℃ and with cathodic current density 0.2～10 A·dm^-2. The industrialpractice shows that, the suggested bath is stable, and the deposits obtained are bright, corrosionresistive and the nickel contents are controllable conveniently in the range of 9～20 percent.

Keywords

Alkaline, Plating, Electredeposition, Zinc-nickel alloy

DOI Link

https://doi.org/10.61558/2993-074X.3046

Publication Date

1995-08-28

Online Available Date

1995-08-28

Revised Date

1995-03-30

Received Date

1994-08-30

Recommended Citation

Jiale Cai, Shaomin Zhou. Studies on the Bright Zinc-Nickel Alloy Palting in Alkaline Baths[J]. Journal of Electrochemistry, 1995 , 1(3): 332-338.
DOI: 10.61558/2993-074X.3046
Available at: https://jelectrochem.xmu.edu.cn/journal/vol1/iss3/20