Microstructure and corrosion resistance of Ni-Al2O3-SiC nanocomposite coatings produced by electrodeposition technique

Ni-Al2O3-SiC nanocomposite coatings were electro-deposited on steel in a typical Watt's bath containing Al2O3 and SiC nanoparticles. Afterwards, the effect of the nanoparticle concentration in the electrolyte bath (ranging from 0 g/L to 40 g/L) on the microstructure and corrosion performance was evaluated. To investigate the microstructural changes and surface morphology of the coatings, as well as the nanoparticle distribution in the deposits, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy was utilized. Also, transmission electron microscopy was performed to further investigate the microstructure and to confirm the production of the nanocomposite coating. The electrochemical corrosion behavior of the prepared coatings was investigated in a 3.5 wt % NaCl solution by a potentiostat-galvanostat device. It was found that desirable structure of the protruding crystallite morphology with no detectable cracks and pores can be achieved at the medium concentrations of the reinforcement (e.g. 20 g/L). It was also found that the corrosion resistance of the coatings is considerably improved by adding the Al2O3+SiC nanoparticles to the Ni matrix. The optimum concentration of the nanoparticles in the electrolyte bath to attain the nanocomposite coating with a desirable microstructure and consequently a desirable corrosion resistance was 20 g/L.