Ni-Co alloys plated by pulse currents

Pulse electrodeposition of Ni-Co alloys was carried out to obtain adherent and compact surfaces with a controlled film thickness. Ni-Co alloys were deposited by applying current pulses with different pulse parameters on Cu substrates at 35 degrees C from aqueous electrolyte. The morphology and the composition of the alloys were analysed by SEM and EDX, respectively. XRD was used to determine metallic phases. Scanning electron micrographs revealed that the deposition parameters had a strong effect on the structure of the alloys. Deposits of a compact structure and the smallest grain size were obtained at low peak current density and long off-time. Increasing peak current density or decreasing off-time led to a rougher structure. Electrochemical characteristics of the Ni-Co deposits were investigated by cyclic voltammetry in 1 mol dm(-3) NaOH and a small amount of dissolution both of Ni and Co occurred in the solution. In general, alloys with a compact structure were found to have better corrosion characteristics compared to the metal layers. Crown Copyright (c) 2005 Published by Elsevier B.V. All rights reserved.