Corrosion inhibiting action of Ni–Mo alloy coatings in the presence of mixed metal oxide nanocomposites
This paper is an attempt to establish the role of mixed metal oxide nanoparticles of ZnO–SnO2 (ZTO), ZnO–WO3 (ZWO) and ZnO–TiO2 (ZTiO) for enhancement of the corrosion inhibiting action of Ni–Mo alloy coatings on a copper substrate. Binary Ni–Mo alloy coatings were electrodeposited on copper plates in the presence and absence of nanoparticles from an alkaline citrate bath. The nanoparticles were previously synthesized via an electrochemical thermal technique. The corrosion resistance of these alloy coatings was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation techniques in 3.5% NaCl medium. The experimental results reveal that the corrosion inhibiting capacity of the coating is best enhanced in the presence of ZWO nanoparticles deposited at the optimum current density (c.d.). Changes in surface morphology, phase structure and composition were analysed using SEM, XRD, and EDX. It was observed that alloy coatings reinforced with nanoparticles possessed a much smoother surface microstructure which could result in superior corrosion resistance.