Sensitivity of Corrosion Behavior for Fe-Based Amorphous Coating to Temperature and Chloride Concentration

The effects of solution concentration and temperature on the electrochemical behavior of the Fe-based amorphous (AMCs) coatings in NaCl solution were studied by using conventional electrochemical measurement and XPS analysis. Results indicated that as solution concentration and temperature increased, the current density for the Fe-based AMCs increased and the pitting potential decreased. This reduced corrosion resistance was derived from the decreased passivation index and polarization resistance, which contributed to the decrease of the induction time (t(m)) for the initiation of corrosion pit. The passive films formed on Fe-based AMCs exhibit two types' semiconductors higher and lower the flat band potential. The decrease of protectiveness of the passive film was mainly correlated with the reduction of Cr2O3 content, the increase of carrier density and the decrease of the work function (W-F).