Localization index obtained from electrochemical noise analysis

The localization index (LI), which is defined as the ratio of the standard deviation and the root square mean (rms) of current fluctuation determined in electrochemical noise measurements, can have values between 0 and 1. It has been proposed in the literature that the LI can be used to determine the nature of the prevailing corrosion mechanism with values of 1 being characteristic of localized corrosion. Experimental data for mild steel in sodium chloride (NaCl) have produced LI values close to 0, while the Lifer a Ti alloy in Ringer's solution was found to be close to 1. It was concluded that the LI should be considered as a measure of the deviation from the assumed identical behavior of the two test electrodes and not as an indicator of corrosion mechanisms.