The Inhibition of Anomalous Codeposition of Iron-Group Alloys Using Cyclic Voltammetry

Binary iron-group deposits, including Co-Ni, Fe-Co, Fe-Ni, Zn-Fe, and Zn-Ni alloys, with composition equal to that of the plating baths, were electroplated using cyclic voltammetry (CV) in suitable potential regions. Three processes, corresponding to cathodic deposition, double-layer response, and anodic dissolution, were found on the CV curves of deposition. The dissolution of newly deposited metal atoms caused the codissolution of an adsorbed monohydroxide layer in the anodic dissolution process, resulting in the inhibition of anomalous codeposition for these iron-group alloys. This proposal was further confirmed by an electrochemical impedance spectroscopic study. The anodic stripping of linear sweep voltammetry and the X-ray diffraction patterns demonstrated the poor-crystalline or amorphous nature of Zn-Ni alloys in different phases. © 2002 The Electrochemical Society. All rights reserved.