Abstract
The atmospheric corrosion of Ni-bearing low alloy steels was investigated by wet/dry cyclic corrosion tests (CCT) in a 0.3%NaCl solution at 30 °C and 60% relative humidity (RH). The prepared samples were studied using gravimetry, electrochemical corrosion tests (polarization curves (PC), electrochemical impedance spectroscopy (EIS)) and analytical techniques (SEM and XRD). The Ni-bearing steels showed higher corrosion resistance than that of mild steel in the test. The results of electrochemical tests demonstrated that the addition of Ni to mild steel restrained anodic dissolution of iron, shifted the corrosion potential (Ecorr) in a noble direction and increased the corrosion resistance of rust layer by improving the adhesion and compactness of the rust layer and ameliorating the physicochemical property of the substrate/rust interfaces. The rust analysis demonstrated that Ni alloying ameliorated rust composition by facilitating the formation of fine NiFe2O4, α-FeOOH and decreasing the β-FeOOH, γ-FeOOH and Fe3O4. In addition, Ni alloying could retard the crystallization of α-FeOOH, Fe3O4 and γ-FeOOH to a certain extent.
Published Version
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