Passivation Behavior of 2507 Super Duplex Stainless Steel in Simulated Concrete Pore Solution

摘要

This study compares the difference between primary and secondary passive films formed on 2507 super duplex stainless steel (SDSS) in simulated concrete pore solution by means of electrochemical analysis and x-ray photoelectron spectroscopy (XPS) combined with atomic force microscopy (AFM). The results reveal that the primary film possesses superior corrosion resistance as indicated by the lower passive current density, higher polarization resistance, and smaller amounts of defects within the passive film. The structure characterized by particles with different heights and diameters in the secondary passive film facilitates the film degradation. Moreover, at 0.48V(SCE), the CrO3 is formed in the secondary passive film, and the Fe species is more prone to transform to FeOOH and Fe2O3.