Electrochemical Behavior and Compositions of Passive Films of Amorphous Ni-P Coating in Acidic Environment

摘要

Amorphous Ni-P coating without pores was prepared by electroless plating. The electrochemicalbehavior of the as-plated Ni-P coating was investigated by potentiodynamic testing in 5 wt. % sulfuricacid solution. Results indicated that the high-phosphorus Ni-P coating has a passivation region in theacid solution. The passive films possessed n-type semiconductor characteristic basing on the Mott- Schottky analysis. Different anodic potentials and polarization time affect the passive films properties.The passive film shows the best corrosion resistance when the potentiostatic potential was 0.1 V andthe polarization time was 30 min. XPS results show that the passive film consisted by Ni(OH)2 andNi3(PO4)2.