The Influence of Co Concentration on the Properties of Conventionally Electrodeposited Ni–Co–Al2O3–SiC Nanocomposite Coatings

Abstract

In this study, Ni–Co–Al2O3–SiC nanocomposite coatings with varying concentrations of Co were electrodeposited in a modified watts bath using conventional electrodeposition technique. The microhardness, surface morphology and phase structure of the coatings were characterized using Vickers microhardness tester, scanning electron microscopy and X-ray diffraction, respectively. The corrosion resistance of the composite coating was evaluated in 3.5% NaCl solution using an electrochemical work station. Increase in Co concentration in the electrolyte resulted in an increase in the microhardness of the nanocomposite coating. Corrosion resistance of coatings was also seen to increase considerably with increase in Co concentration in electrolyte. This was attributed mainly to the decrease in grain size, chemical composition, phase structure and preferred orientation of the coatings. The increase in Co in the electrolyte had a significant effect on the crystallite size of the Ni–Co–Al2O3–SiC coatings.