The Annals of “Dunarea de Jos” University of Galati. Fascicle IX, Metallurgy and Materials Science (Dec 2010)
Electrochemical Corrosion Properties of SiC/Ni Nano-Composite Coatings in 0.5M NaCl
Abstract
Nano particles have an influence on nickel electrocrystallisation steps: decreasing charge transfer resistance and activating the nickel reduction. The SEM – EDX surface morphology and TEM structure of the electrodeposited nanocomposite were investigated. The dispersed particles perturb the nickel crystal growth resulting in a random rather than in a preferred orientation. The corrosion behaviour of the nano-composite coatings was evaluated in the solution of 0.5M NaCl at room temperature. It was found that the polarization resistances of nanoSiC–nickel composite coatings are higher compared pure nickel coatings. The SiC distribution in the nano-composite coatings at low concentrations of SiC in bath was uniform across the coatings. The incorporation of the SiC nano-particles leads to the changes in the morphology and corrosion resistance of the nano-composite coatings as compared to the pure nickel coatings. The Ni–SiC nano-composite coatings have higher corrosion resistance than the pure nickel coating, which is attributed to the grain-fining and dispersive strengthening effects of the co-deposited SiC nano-particles with nickel. The silicon carbide nano particles embedded during nickel electroplating have a good effect to corrosion properties of composite coating compared to pure nickel coating. The polarization resistance increases about two times and the corrosion current density decreases about two times in the case of nano-composite coating.
