Natural Passivation Behavior and Corrosion Resistance of HRB400 Steel in Simulated Concrete Pore Solution
The natural passivation behavior of HRB400 steel in simulated concrete pore solution,i.e.a saturated Ca(OH)2 solution with pH 12.5 was investigated via measurements of open circuit potential,electrochemical impedance spectra,and Mott-Schottky curves.The composition and structure of the pas-sivation film were characterized by X-ray photoelectron spectroscope and atomic force microscope.Sub-sequently,the resistance to Cl-attack of the passivation film formed by the natural passivation in saturat-ed Ca(OH)2 solution with varying pH values was further studied with dynamic potential polarization curve measurement,SVET technique,and SEM in terms of corrosion morphology and corrosion products.The results indicate that HRB400 steel requires at least 72 h to form a stable passivation film in simulated con-crete pore solution,and the structure and composition of the passivation film are subsequently changed during the process.The stable passivation film exhibits excellent resistance to chloride ion attack with a critical chloride ion concentration range of 0.1 to 0.15 mol/L,which is well consistent with the results of SEM characterization.
HRB400 steelsimulated concrete pore solutionnatural passivationpassivation filmcritical chloride ion concentration
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