The determination of coating performance with impedance measurements—III. in situ determination of loss of adhesion
The determination of coating performance with impedance measurements—III. in situ determination of loss of adhesion
复制标题
DOI：
10.1016/0010-938x(94)90198-8
复制
发表时间：
1994-06
影响因子：
8.3
通讯作者：
E. V. Westing;G. Ferrari;J. Wit
中科院分区：
文献类型：
--
作者：
E. V. Westing;G. Ferrari;J. Wit
现代涂料的防腐蚀性能的提高是通过（最佳）阻隔性能实现的。这意味着涂层的高DC电阻，这阻碍了用电化学阻抗谱（EIS）对这些涂层进行测量的常见解释方式。EIS测量的结果用于根据涂层的电容行为和/或DC电阻进行评估。在早期的论文中表明，涂层可以从环境中吸收水，同时直流电阻保持非常高（> 100 Ω cm 2）。在本文中，它示出的附着力的损失可能会发生，而直流电阻仍然很高。环氧阻隔涂层的附着力损失之前，涂层的一部分的过度溶胀，这反映了环氧涂层的介电性能的变化。为了检测这些变化，有必要在阻抗的等效中使用恒定相位元件（CPE）。当使用电容器时，不能清楚地检测介电性质的变化。一个模拟与一个部分，过度膨胀的涂层的阻抗模型描述了测量的响应，并解释了结果之间的差异时，电容器和CPE在等效电路中使用。
The increased anti-corrosion performance of modern coatings is among others achieved by the (optimal) barrier properties. This implies a high DC resistance of the coating, which hinders the common way of interpreting measurements on these coatings carried out with Electrochemical Impedance Spectroscopy (EIS). Results of EIS measurements use to be evaluated in terms of capacitive behaviour and/or DC resistance of the coatings. It was shown in earlier papers that coatings can take up water from the environment while the DC resistance remained very high (> 100 Ω cm 2). In this paper it is shown that loss of adhesion could take place while the DC resistance remained very high. The loss of adhesion of epoxy barrier coatings is preceded by an excessive swelling of a part of the coating, which is reflected by a change of the dielectrical properties of the epoxy coating. In order to detect these changes it is necessary to use a Constant Phase Element (CPE) in the equivalent of the impedance. When using a capacitor the changes of the dielectrical properties cannot be clearly detected. A simulation with a model for the impedance of a coating with a part that swells excessively describes the measured response and explains the differences between the results when a capacitor and a CPE is used in the equivalent circuit.