Corrosion resistance of Cu‐bearing 316L stainless steel tuned by various passivation potentials

Abstract

Three incremental passivation potentials (0.2, 0.5, and 0.8 VSCE) were selected to passivate the 316L‐Cu stainless steel (SS) and the 316L SS in 0.5 M H2SO4 solution, with the aim to investigate the corrosion resistance differences of two SSs in 0.9 wt.% NaCl solution. Various electrochemical tests including potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Mott–Schottky analytical method assisted with X‐ray photoelectron spectroscopy (XPS) were employed. The results indicated that 316L‐Cu SS after passivation in 0.5 M H2SO4 solution showed no influence on the double‐layer structure of passive films. Besides, increased passivation potential augmented the electron donor concentration (ND) and the hole accepter concentration (NA) of the passive film on the 316L‐Cu SS, hinting a gradually declined compactness of the passive film. EIS results further affirmed that the passive film stability of 316L‐Cu SS followed the same tendency with increased passivation potential. XPS results hinted that the oxidation reaction of Cu element switching into Cu2+ and Cu+ ions promoted the dissolution of Cu ions and weakened the passive film stability of 316L‐Cu SS.