Influence of surfactant concentration on structural properties and corrosion behaviour of electrodeposited Ni–SiO2 nanocomposite coatings

Abstract

Abstract In this study, Ni–SiO2 nanocomposite coatings were deposited on the surface of X70 steel by performing direct current electrodeposition. The effect of different concentrations of cetyltrimethylammonium bromide surfactant (0.3, 0.5, 1, and 2 g L−1) on particle distribution and corrosion behaviour of the coatings was analysed. The structural properties of the obtained coatings were evaluated by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy analysis, X-ray diffraction, and atomic force microscopy. The corrosion behaviour of the coatings was tested by potentiodynamic polarisation and electrochemical impedance spectroscopy. The results showed that the electrodeposited coatings obtained from the electroplating bath with 1 g L−1 of surfactant modified the surface morphology of the Ni–SiO2 nanocomposite coating and presented a finer and more uniform microstructure. The results of the phase structure analysis showed that the addition of the surfactant in the electrodeposition process changed the preferred orientations for the coatings from (111) to (220) and (200) planes. The anti-corrosion performance of the resulting coating produced in the presence of 1 g L−1 of surfactant was significantly higher than the anti-corrosion performance of the other coatings and showed a lower corrosion rate.