Effects of electroplating variables on the composition and morphology of nickel-cobalt deposits plated through means of cyclic voltammetry

Abstract

The effects of temperature and pH of the plating baths as well as the potential range and cycle number of cyclic voltammetry on the composition and morphology of Ni-Co deposits were systematically investigated. A reaction scheme corresponding to the Ni-Co codeposition was proposed. Nickel-cobalt deposits with the composition approximately equal to their corresponding plating solutions (based on the metal content) were formed when pH of the plating bath was equal to 2.0 and the potential range of CV was between 0 and -1.2 V. This complete depression in the anomaly of Ni-Co codeposition was attributed to the anodic dissolution of the freshly deposited metal atoms resulting in the simultaneous dissolution of the adsorbed monohydroxide species occurring between -0.3 and 0 V. The effects of temperature and pH of the plating bath, the cycle number and potential range of CV on the morphology, loading, or crystalline structure of Ni-Co deposits were also compared. © 2002 Elsevier Science Ltd. All rights reserved.