Noise resistance applied to corrosion measurements .2. Experimental tests

Electrochemical noise (EN) measurements have been carried out on several corroding systems, utilizing the technique of simultaneous recording of current and voltage fluctuations, and calculating the frequency dependent spectral noise impedance R(sn)(f) as the square root of the ratio of the power spectral densities (PSD) of the voltage to current noise. The results are compared with the theoretical predictions stemming from an analysis of the technique, which is presented in the preceding paper.(1) It is shown that, over a quite large range of conditions, R(sn), coincides with the impedance modulus of the electrodes under study. From the relationship between R(sn) and the noise resistance R(n), which is usually obtained calculating the ratio of the standard deviations of the voltage and current fluctuations, it is shown that the latter quantity can be equal to the zero frequency Limit of the impedance only if certain conditions are satisfied.