Passive Film Characteristics and Corrosion Resistance of S32205 Duplex Stainless Steel and N09925 Nickel-Based Alloy in 3.5% NaCl Environment

The passive film characteristics and corrosion resistance of S32205 duplex stainless steel and N09925 nickel-based alloy in 3.5% NaCl solution were studied by Mott-Schottky analysis method, electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). The results show that the defect density of the passivation film on the surface of N09925 nickel-based alloy was lower than that of S32205 duplex stainless steel. The passivation films on the surface of the two materials were enriched with Fe and Cr elements, and the main components were oxides and hydroxides of Cr and Fe. The passivation film on the surface of duplex stainless steel S32205 contained a small amount of metal Ni. The passivation film on the surface of Ni-based alloy N09925 had a higher Ni content, and also contained Ni oxides and hydroxides. The impedance value of N09925 nickel-based alloy was higher, and its film resistance and charge transfer resistance were higher than those of S32205 duplex stainless steel, indicating that the protective effect of the passivation film on the surface of N09925 nickel-based alloy was higher than that of S32205 duplex stainless steel.