Determination of the polarization resistance from impedance measurements

Four different methods for determining the polarization resistance R from impedance data are discussed. These methods are suitable for online corrosion monitoring. Their use is illustrated for iron in tapwater and in neutral, aerated Na₂SO₄ containing various inhibitors. R-values obtained with the CIRFIT-method are compared with R which is obtained from a linear sweep through E_corr. The integration method has the advantage of computation speed.