碳钢在含Cl- 和SO42-碱性溶液中腐蚀规律的局部交流阻抗

 通过局部交流阻抗(LEIS)研究了碳钢在含Cl^-和SO₄^2-中性和碱性溶液中的腐蚀行为,并采用显微激光拉曼光谱技术进行了腐蚀产物的分析.研究结果表明,碳钢在中性和碱性溶液中均发生不同程度的腐蚀.在浸泡初期,碱性溶液中的腐蚀速率小于中性溶液中的腐蚀速率,碳钢表面在相对较短时间内形成γ-FeOOH腐蚀产物,起到较好的阻碍Cl^-和SO₄^2-阴离子侵蚀的作用.随着在溶液中浸泡时间的延长,由于Cl^-和SO₄^2-阴离子的侵蚀作用,以及在初期对基体起到保护作用的腐蚀产物膜的破损,导致平均阻抗值的降低.特别是在碱性溶液中起始阶段具有较高的平均阻抗值,但在浸泡过程中,其平均阻抗值快速地降低,表明溶液中的Cl^-和SO₄^2-阴离子对腐蚀产物膜的侵蚀作用将促进Q235碳钢的腐蚀发展.

Localized Electrochemical Impedance Spectroscopy of the Corrosion Behavior of Carbon Steel in the Alkaline Solutions with Cl- and SO42-

The corrosion behavior of carbon steel in the neutral and alkaline solutions with Cl^- and SO₄^2- were investigated by Localized Electrochemical Impedance Spectroscopy (LEIS) technique. The corrosion products on the surface of sample were analyzed by Laser Micro-Raman Spectrometry. The experimental results indicated that the corrosion rate in the neutral solution was higher than that in the alkaline solution during the initial stage of immersion. In the neutral solution, the corrosion products were rapidly deposited on the surface of the sample. The corrosion products film was composed of γ-FeOOH, which could protect matrix of Q235 carbon steel and reduce the ion penetration. As the immersion time increased, the Cl^- and SO₄^2- ions damaged corrosion product films. Especially in the alkaline solution during the initial stage, the average impedance value was much higher. But the average impedance rapidly decreased with increase of the steeping time. Moreover, the destructive effect of Cl^- and SO₄^2- ions on the passive film is also demonstrated in corrosion process through the change of impedance value as the steeping time increases.