Effects of Cl^{∿/sup> Ions on the Corrosion Behaviour of Low Alloy Steel in Deaerated Bicarbonate Solutions}

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• 作者：Yunfei Lu¹ ; ² ; Junhua Dong¹ ; ^{jhdong@imr.ac.cn" class="auth_mail" title="E-mail the corresponding author} ; Wei Ke¹
• 关键词：Low alloy steel ; Corrosion behaviour ; Cl&minus ; Open circuit potential ; Electrochemical impedance spectroscopy (EIS)
• 刊名：Journal of Materials Science & Technology
• 出版年：2016
• 出版时间：April 2016
• 年：2016
• 卷：32
• 期：4
• 页码：341-348
• 全文大小：3127 K

文摘

The effect of Cl⁻ ions on corrosion evolution of NiCu low alloy steel during immersion tests (up to 70 days) in deaerated 0.05 mol/L bicarbonate solutions was investigated by in-situ electrochemical measurements combined with X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) characterisations. The results showed that due to the acceleration of substrate dissolution in the presence of Cl⁻, corrosion of NiCu low alloy steel underwent only two stages, i.e., a quick oxidation process followed by a final metastable passive state, without the initial slow anodic dissolution as observed in the Cl⁻-free bicarbonate solution. The main components of the formed rust layer in the Cl⁻-free bicarbonate solution were α-FeOOH and Fe₃O₄, while apart from α-FeOOH, Fe₆(OH)₁₂CO₃ was found evident instead of Fe₃O₄ in the Cl⁻-containing solution. Metastable pits were only found in the Cl⁻-containing solution where Cl⁻ accumulated after the immersion test, confirming the attack of Cl⁻ on the substrate after penetrating the formed corrosion product layer.