Electrochemical corrosion behavior of electroless Ni-P coating in NaCl and H_2SO_4 solutions

摘要

Electrochemical corrosion behavior of electroless Ni-P coating in NaCl and H_2SO_4 solutions were studied by potentiodynamic polarization curves and electrochemical impedance spectra techniques, as well as the corrosion morphology was characterized. The results indicate that electroless Ni-P coating with about 25μm is stable in 30 days immersion in NaCl solution. Although it was corroded with prolonged immersion days, the corrosive medium has not penetrated through the coating. During the H_2SO_4 concentration ranging from 5 to 10%, the corrosion current density of electroless Ni-P coating increased due to the intensified anodic dissolution process; in 15% H_2SO_4 solution, electroless Ni-P coating shows obvious anodic passivation effect.