Effect of pulse parameters on the passive layer formation on pulse plated Ni–Co alloys

From a chloride bath, Ni–Co alloys were pulse plated by varying the pulse parameters off-time and the peak current densities using a pulse generator that applies a square wave signal in order to examine the mechanism of the passive oxide layer formation on the deposited coatings in the frame of pulse parameters. Cyclic voltammetry and potential step measurements were carried out in order to characterise the electrochemical behaviour on the Ni–Co coatings at a selected electrode potential in an alkaline solution. Calculation of the oxide layer formation was evaluated from the total charge, determined by recorded current–time transients and from ICP-analysis of the samples. The most protective and compact oxide was formed on the sample that was deposited at low current densities and at high off-time.