WBE联合LP技术研究海水/海泥界面碳钢的腐蚀行为

利用阵列电极技术捕获了在不同浸泡时间下每个微电极与其它99个微电极整体的电偶电流,分析获得了海水/海泥界面附近阴、阳极分布区域的变化规律；利用线性极化和电化学阻抗技术对垂直海水/海泥界面的一行微电极进行测试,获得了距海水/海泥界面不同距离的微电极的腐蚀电流、腐蚀电位,并观察了腐蚀形貌,探讨了其腐蚀机理。结果表明：平行于海水/海泥界面的海泥区域为电偶腐蚀阳极区、对应的海水区域为电偶腐蚀阴极区域；海水/海泥界面区金属的腐蚀是由电位差、溶解氧浓度、海泥阻抗等多因素控制；腐蚀主要区域是近海水/海泥界面的海泥区域及远海水/海泥界面的海水区域。海水中较高浓度的氧促进了腐蚀产物的致密化,而海泥中缺氧环境及微生物抑制了腐蚀产物的致密化。

Evaluation of Carbon Steel Corrosion in Vicinity of Interface Sea-water/Sea-mud by Techniques WBE and LP

Serious corrosion problem could be found in the vicinity of the interface sea-water/sea- mud (VISS) for marine structures of steels. The corrosion of carbon steel in an artificial environment as a simulation of the above VISS was studied by means of wire beam electrode (WBE) technique, linear polarization (LP) technique, electrochemical impedance spectroscopy (EIS) and corrosion morphology examination etc. For the simulated VISS, the sea-water and sea- mud were taken directly from Zhanjiang bay of the South China sea. The galvanic current between one electrode and another electrode among the rest 99 electrodes was successively measured by WBE technique, and the change of the cathode area and anode area was acquired from the results of the measurement of galvanic current. The E_corr and I_corr of the electrodes of carbon steel, which were perpendicular to the interface of sea-water/sea-mud (ISS), were obtained by the linear polarization technique. Then the corrosion morphology of the tested electrodes was observed by stereo microscope. The results show that the portion under ISS of an immersed electrode of carbon steel acts as anode, and that above ISS acts as cathode. The corrosion of carbon steel in the VISS was controlled by the potential difference, the dissolve oxygen concentration and the sea-mud impedance. The areas both of where near by the ISS on the anode portion and where far from the ISS on the cathode portion were the serious corrosion areas. Correspondingly of which the formed corrosion product on the former was fluffy and low adhesive, while that on the later was compact and strongly adhesive.