Local electrochemical impedance spectroscopy (LEIS) and mapping (LEIM) were used in situ to follow blistering on a model epoxy-coated, hot-dip galvanized steel without any initial artificial defects during alternating open circuit potential (OCP)/cathodic polarization cycles. Zones with high admittance were evident from the early stages of degradation, when no blisters were visible. Some of the zones (type I) could be distinguished on the admittance maps obtained at both open circuit and applied cathodic potentials. Other zones (type II) were not detectable by LEIM at OCP but were visible on the maps obtained under cathodic polarization. Blisters developed on both types of zones. Comparing the LEIS responses of the blistered zones with the responses of a model Zn/Cu galvanic couple, the observed behavior was attributed to the formation of a galvanic couple between the blisters, and consequently a gradual increase of anodic and cathodic activities in blisters of types I and II. LEIM is a flexible tool able to differentiate in situ between the development of anodic and cathodic zones on immersed polymer-coated metallic substrates on application of different DC biases or AC frequencies.

原位电化学阻抗谱（LEIS）和标测（LEIM）用于在交替开路电势（OCP）/阴极极化循环期间在模型环氧树脂涂层的热浸镀锌钢上起泡，而没有任何初始的人工缺陷。从降解的早期阶段就可以看到高导纳的区域，此时看不到水泡。在开路和施加的阴极电势下获得的导纳图上，可以区分出某些区域（I型）。其他区域（II型）在OCP处无法通过LEIM探测到，但在阴极极化下获得的图上可见。在两种类型的区域上都会出现水泡。比较起泡区的LEIS响应与模型Zn / Cu电偶的响应，观察到的行为归因于在水泡之间形成了电偶，因此在I型和II型水泡中阳极和阴极活性逐渐增加。LEIM是一种灵活的工具，可以通过施加不同的DC偏置或AC频率，在浸没的聚合物涂层金属基板上原位区分阳极区和阴极区的发展。