Abstract
The dispersion occurring during impedance measurements on corroding metal surfaces can be mathematically represented by the introduction of a frequency-dependent impedance Z 2( ω). In order to determine this impedance physically, an analysis of the term Z 2( ω) = K 2 −1( jω) − α2 is carried out. Supplementary to the conventional transmission line model for solid electrodes, a new model is presented. The occurrence of frequency-dependent elements is explained here as a superposition of many partial reactions in the form of R p — C p elements in series circuit. The frequency of the individual relaxation times is determined by means of the empirical distribution expression by Cole and Cole. It is shown that the results of impedance measurements on zinc-plated electrodes with a defective polymer layer after an intensive chemical loading can be represented by this model. The causes of dispersion are discussed in a general way.
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