Abstract
This article introduces two techniques for characterizing individual transients in electrochemical noise (EN) data in the time domain. These approaches extract information from only electrochemical transients in EN data, i.e. where current and potential are correlated. An algorithm is introduced for identifying transients based on locating records where both the current and potential derivatives are simultaneously zero. A measure of the intensity of the transient was obtained from the current amplitude near the transient apex. A measure of the uniform corrosion rate of the less active electrode during a transient was obtained from the ratio of differences in potential and current during a single transient. The corrosion rates thus obtained appear to have a lognormal distribution. These techniques were illustrated from laboratory measurements for three systems, i.e. carbon steel (UNS G10100) electrodes in saline and two magnesium alloys, AZ91D (UNS M11916) and ZA1040 (experimental alloy), in saline/magnesium hydroxide solutions. This approach seems to be readily transportable to a field monitoring system as long as the sampling frequency is high enough and there is a processor available to convert raw data as it is collected and store only the processed results.
