应用EFM技术检测碳钢在海水中的腐蚀行为

Using electrochemical frequency modulation technique to detect corrosion of carbon steel in seawater

电化学频率调制(electrochemical frequency modulation,EFM)是一种腐蚀速度检测的新方法,能够同时测得腐蚀电流密度和Tafel常数。本文以恒电位仪、笔记本电脑、数据采集卡和LabVIEW开发的应用程序建立了EFM测试系统,将其用于低碳钢/海水体系,研究了扰动频率等测试参数对EFM测试结果的影响。在实验室应用EFM方法检测了Q235钢在NaCl溶液和舟山海水中的早期腐蚀速度,并与其他电化学方法进行了比较。结果表明,在低碳钢/海水体系中EFM方法测得的腐蚀速度因界面电容行为的影响而偏大,但EFM技术和测试系统仍然可以作为海洋腐蚀现场检测的一种理想选择。

A system for electrochemical frequency modulation （EFM） measurement was set up, which consisted of a potentiostat, a laptop computer, a NI DAQ card and application softwares developed with LabVIEW 7.0. The system was used to detect the corrosion rate of carbon steel/seawater system. The influence of such test parameters as perturbation frequency on the EFM results was studied. The early corrosion rate for Q235 steel in Zhoushan seawater was determined in laboratory with the EFM technique as well as two general electrochemical techniques-analysis of the polarization curve in the vicinity of the corrosion potential and electrochemical impedance spectroscopy （EIS） . The corrosion rate determined with EFM technique was a little higher than the real value due to the capacitance behavior influence, while the advantages of the EFM technique still make it an ideal candidate for detecting and monitoring the carbon steel coupons＇corrosion at the marine corrosion test sites.