碱性电镀光亮锌镍合金研究

在总结镀液的电化学特性和锌镍合金镀层的晶体结构与性能等实验结果的基础上，提出碱性电镀光亮锌镍合金的工艺规范和直接把锌酸盐镀锌液转化为碱性电镀光亮锌镍合金镀液的方法。生产实践证明，该工艺稳定，镀层光亮、耐腐性好、硬度较高、无氢脆，镍含量可在９～２０ｗｔ％范围内随意控制。

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

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 Zn￣(2+)/Ni￣(2+) ratio in the baths and with increasing ofcathodic 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-electrede 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 ofZN-11 additive on nickel deposition and the catalytic effect of the used complexing agent on zincdeposition.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% behavesmaximum protection to steel.The zinc-nickel alloy deposit with nickel content<10.6 wt% behavesanodic 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-nickelalloy 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,Zn￣(2+)/Ni￣(2+) ratio(wt.)is 4 to 10. Thebath 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 9～2 0 percent.