Electrochemical Noise Analysis of Iron Exposed to NaCl Solutions of Different Corrosivity

Potential and current noise data have been collected for pure iron foils which were exposed to 0.5 N which was aerated, deaerated, or aerated with added as inhibitor. Data were obtained at the beginning of each hour over a 24 h period. The noise data were displayed as power spectral density plots or as the rms values of potential and current . The potential noise data seem to be affected by fluctuations of mass transport and did not agree with the known corrosion behavior of the systems under investigation. However, good agreement was observed for the current noise data. For the noise resistance similar values as for the polarization resistance determined with EIS at the end of the tests were obtained. The pit index defined by others as , where is the mean current in a noise measurement, did not provide meaningful information. The experimental data obtained in this investigation have been compared with those reported previously by Lumsden et al.