海洋大气环境中电镀锌板的腐蚀行为与机理

通过2 a现场暴晒实验,采用腐蚀形貌宏观观察、SEM、XRD及失重法,对电镀锌板在青岛和西双版纳大气环境中的腐蚀行为进行了研究。通过电化学阻抗谱研究了电镀锌板在不同Cl^-浓度溶液中的腐蚀电化学行为。结果表明：电镀锌板在青岛和西双版纳大气环境中的平均腐蚀速率分别为0.76和0.1935 μm/a,在青岛大气环境中暴晒2 a后局部有红锈产生,主要腐蚀产物为Zn₅(OH)₈Cl₂H₂O,ZnO和Zn(OH)₂,在西双版纳大气环境中表面有少量白色锈点,主要腐蚀产物为2ZnCO₃3Zn(OH)₂,ZnO和Zn(OH)₂。电镀锌板在青岛和西双版纳大气环境中主要表现为均匀腐蚀,并伴有局部不均匀坑蚀;青岛大气环境中的Cl^-使电镀锌板在青岛大气环境中的腐蚀加剧。

Corrosion Behavior of Field-Exposed Electrogalvanized Steel Plate in Marine Atmosphere

Corrosion behavior of electrogalvanized steel plate exposed to atmospheres at Qingdao located at the East coast of China and Xishuangbanna, an area of tropical rainforest climate, located at Yunnan province respectively for 2 a was investigated by means of weight-loss measurement, macro-morphology observation, SEM and XRD etc. The electrochemical behavior of the plate in solutions with different chloride concentration was studied by electrochemical impedance spectroscopy. The results showed that the corrosion rates of the steel exposed to the atmospheres at Qingdao and Xishuangbanna are 0.76 and 0.1935 μm/a respectively. Local red rust was observed on the surface of the steel plate exposed to Qingdao atmosphere, which consists of Zn₅(OH)₈Cl₂H₂O, ZnO and Zn(OH)₂. In the atmosphere at Xishuangbanna, the main corrosion products are 2ZnCO₃3Zn(OH)₂, ZnO and Zn(OH)₂. Inhomogeneous general corrosion occurs in the two test areas and the electrogalvanized steel plate suffered more severely from corrosion in the atmosphere at Qingdao because of the influence of Cl^-.