Effect of pH and current density on the electrodeposition of Zn-Ni-Fe alloys from a sulfate bath

摘要

An investigation was done on the influences of current density and pH on the electrodeposition behavior of Zn-Ni-Fe alloys using a sulfate bath. The bath consisted of 0.1 M ZnSO_4, 0.1 M NiSO_4, 0.1 M FeSO_4, 0.2 M Na_2SO_4, 0.2 M H_3BO_3, and 0.01 M H_2SO_4. The results of Zn-Ni-Fe alloys' codeposition revealed that the significant inhibition of Ni and Fe deposition takes place because of the presence of Zn~(2+) in the plating bath. A transition current density was noticed above wherein a transition from normal to anomalous deposition took place. Bright and uniform surface appearance deposits of Zn-Ni-Fe were the results obtained at pH range 2-5, and the deposits showed high corrosion resistance. During the investigation, the usage of cyclic voltammetry and galvano-static techniques for electrodeposition were utilized, while linear polarization resistance and anodic linear sweeping voltammetry techniques were used for the corrosion study. Characterization of morphology and the chemical composition of the deposits were performed by means of scanning electron microscopy and atomic absorption spectroscopy.