SITE-BLOCKING EFFECT OF Ce ON THE PASSIVE FILM FORMED ON Ni-Cu COATINGS

Abstract

In this work, Ni-Cu coatings were obtained using the pulse current electrodeposition technique from electrolyte with 0, 150, 190 and 230mg/L ceric sulfate. The modification of Ce on microstructure and electrochemical of Ni-Cu coatings were examined. The composition of the passive film forms on samples were examined. The results demonstrate that Ni-Cu coating synthesized from 190 mg/L ceric sulfate in the bath shows the best corrosion resistance, Ce accumulates close to the interface (coating/passive film) and gives rise to a “site-blocking” effect on the outward transport of the oxygen vacancies and inward transport of cation vacancies. Ce accumulation enhances the corrosion resistance of Ni-Cu coatings.