Study on Corrosion Resistance of Zn-Ni Electrodeposition Depending on Various Electrolysis Conditions in The Zincate Plating Bath

초록

As the industry becomes more sophisticated, there is a demand for a surface treatment technologies capable of imparting excellent corrosion resistance, wear resistance, hardness and lubricity at high temperatures. Since it is difficult to satisfy these requirements with a single metal plating, research on binary alloy plating has been actively conducted. Among these alloy platings, the Zn-Ni alloy plating has excellent corrosion resistance, heat resistance, economic efficiency, industrial efficiency, and beautiful appearance. In addition, since the Zn-Ni electrodeposited layer has high hardness, the surface is hardly damaged, and various chromate treatments are possible, and thus it is widely used in various industrial fields. This study used a zincate electrolytic bath for Zn-Ni electrodeposition. As the process parameters, the content of NiSO4·6H2O, the organic additives N(CH2CH2OH)3, the current density(0.1-6A/dm2) and the electrodeposition temperature(30-50˚C) were selected. The Ni contents of the Zn-Ni electrodeposited layer was analyzed by EDX according to the process conditions and the surface morphology was observed by SEM as to the Ni contents. By controlling four process parameters, the Ni contents can be electrodeposited at 0.4-80 wt.% and the surface morphology changes. The characteristic of SST(Salt Spray Test) against the corrosion resistance of the electrodeposited layer was investigated according to Ni contents. The Ni contents increases in proportion to the current density, but the addition of organic additives reduces the Ni content. The temperature and NiSO4 · 6H2O contents were proportional to the electrodeposited Ni contents. The corrosion resistance of Zn-Ni electrodeposited layer was considered to be the best corrosion resistance because it produces a single γ-phase at about 10wt%.