Electrochemical development and characterisation of nanostructured Ni–Fe alloy coatings for corrosion protection

Nanostructured Ni–Fe alloy coatings were developed galvanostatically using a new low-concentration bath. The composition and operating parameters of the bath were optimised by taking the benefit of the conventional Hull cell method. Ni–Fe alloy coatings were developed at different current densities (2.0 to 5.0 A dm−2), keeping pH = 2.5. The corrosion behaviour of electrodeposited alloy coatings was evaluated in 3.5% NaCl solution, using Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarisation methods. Ni–Fe alloy coating, deposited at 2.0 A dm−2 exhibited a lesser corrosion rate (14.71 × 10−2 mm y−1) than those at higher current densities. The lowest corrosion rate was attributed to its least crystallite size (10.4 nm), evidenced by an X-Ray Diffraction (XRD) study. The corrosion performance of Ni–Fe alloy coatings was discussed in the light of their surface morphology and composition, evidenced by SEM and Energy-Dispersive X-ray spectroscopy (EDS) analysis, respectively.