双电极碳钢体系在薄液膜初期干燥过程中的阻抗谱演化规律

EVOLVEMENT OF ELECTROCHEMICAL IMPEDANCE SPECTRA OF A Bi-ELECTRODE CELL FOR CARBON STEEL IN THE INITIAL STAGE OF WET/DRY PROCESS

采用电子天平和交流阻抗法在湿干变化环境中原位监测了碳钢双电极体系电化学阻抗谱,并研究了其大气腐蚀初期阻抗谱的演化规律.结果表明,薄液膜较厚时,可以利用简单的传输线模型对电化学阻抗谱进行最小二乘法拟合.薄液膜减薄至128μm以下时,阻抗谱出现Warburg阻抗。当电极表面的薄液膜减薄至不连续时,在腐蚀初期表面没有腐蚀产物的条件下,两电极间的溶液电阻急剧增大,干燥后变为两电极间填充的绝缘材料的电阻.

In-situ monitoring the electrochemical impedance spectra of a two carbon electrode system under wet/dry cyclic condition was carried out by means of an electronic balance and electrochemical impedance technique. The evolvement of impedance spectra of carbon steel in the initial stage of atmospheric corrosion was investigated. The results showed that when the electrolyte film was thick, the simple transmission line model could be used to carry out the nonlinear least squares （CNLS） fits; while the thickness of electrolyte film became thinner than 128 μm. Warburg impedance appeared in the impedance spectra. When the distribution of surface electrolyte film became discontinuous and there wasnt any rust in the initial stage, the solution resistance between the two electrodes increased significantly, and became the resistance of the dielectric material between the two electrodes.