Corrosion Resistance of Pulse Electrodeposited Nanocrystalline Ni Coatings in NaCl Solution and NaOH Solution

Nanocrystalline Ni coatings were prepared by using pulse electrodeposition. The corrosion behavior of the nanocrystalline Ni coatings in 3.5wt% NaCl solution and 10.0wt% NaOH solution was evaluated by using soaking and electrochemical polarization methods respectively. Results indicate that the nanocrystalline Ni coatings have a low corrosion current and a wide passivation zone in 3.5wt% NaCl solution,and their corrosion resistance decreases gradually with the reduction of grain sizes. In 10.0wt% NaOH solution,the corrosion resistance of the coatings increased with the reduction of grain sizes,and wide passive zones also emerged in the Tafel curves of the coatings.