Zn-Ni-La合金电沉积工艺研究

Technology for Electrodeposition of Zn-Ni-La Alloy Coating and Corrosion Resistance of the Coating

研究了在氯化物体系中电镀Zn-Ni-La合金,在Zn-Ni合金镀层中引入La,以达到节约金属镍的目的。发现镀液中加入稀土,能使Zn-Ni-La合金的阴极极化增大近0.2V,使镀层变得更为致密光亮,并提高镀层的综合性能。同时研究了配位剂浓度对Zn-Ni-La合金镀层中稀土含量的影响,发现配位剂的添加使镀层中稀土的含量先增大后降低,分别在20g/L和30g/L时出现最大值。最后,研究了Zn-Ni-La合金的耐蚀性。结果表明:镀层中通过引入稀土元素作为合金元素之一,明显降低了镀层中镍的含量,使镀层中镍含量仅为2%左右的情况下即与Zn-Ni(13%)合金耐蚀性相当。

The technology for electrodeposi-tion of Zn - Ni-La alloy coating from chloride baths was investigated,where rare earth La was introduced to reduce consumption of Ni. The effect of La and complexing agents on the composition and microstructure of the ternary alloy coating were investigated, while the corrosion resistance of the Zn - Ni - La alloy coating was evaluated as well. Results indicated that rare earth La helped to increase the cathode polarization potential of Zn-Ni-La coating by 0. 2 V and improve the compactness brightness of the coating as well. Moreover, the introduction of La also contributed to improve the anti-corrosion ability of the Zn-Ni-La coating. Besides, along with increasing concentration of complexing agents in the plating bath, the concentration of La in the ternary alloy coating first rose and then decreased, and it reached a peak level when the concentrationof the complexing agents was 20 g/L and 30 g/L. Also, the introduction of La in the ternary alloy coating led to a significantdecrease in the content of Ni, and the ternary alloy coating containing about 2% Ni had corrosion resistance comparable to that of Zn-Ni coating containing Ni as much as 13%.