Characterization and corrosion resistance of electrodeposited Ni-Mo-silicate platelet nanocomposite coatings

Nickel-molybdenum-montmorillonite (Ni-Mo-MMT) nanocomposite coatings were prepared by electrodeposition from an alkaline citrate bath containing different concentrations of exfoliated montmorillonite. X-ray diffraction results revealed that the embedding of silicate platelets modified the texture of the Ni-Mo matrix and increased the grain size. Nanoindentation measurements showed increasing microhardness and Young's modulus for the nanocomposite coatings deposited from 1.0 g/L solutions of silicate platelets compared to pure Ni-Mo films. The potentiodynamic polarization and electrochemical impedance measurements showed that the Ni-Mo-MMT nanocomposite layers have higher corrosion resistance in 3.5% NaCl compared to pure Ni-Mo. SEM and AFM micrographs showed a slight increase in the particle size and the surface roughness of the electrodeposited film, respectively as a result of incorporation of MMT particles into the Ni-Mo alloy matrix.