Corrosion Rate Determination by Electrochemical Noise Analysis ENA

Corrosion Rate Determination by Electrochemical Noise Analysis (ENA) 

The electrochemical techniques described in Sects. 7.3.1 and 7.3.2 measure the response of the system to an externally applied perturbation. It is possible to use the inherent noise in the system as a stimulus and measme the system response [27-36]. The fundamental basis to use noise analysis as a determination of corrosion rate is not as strong as that for the other techniques. However, the advantage of noise analysis is that there is no need to apply any external signal, and the system is not polarized at all away from its natural 

A variety of techniques based on noise exists, but the most common uses two identical working electrodes and a noise-free reference electrode situated between the two working electrodes. The current flowing between the two working electrodes is measured by a zero-resistance ammeter, and their potential is monitored versus the reference electrode. 

The noise resistance has been defined as the ratio of the potential/current standard deviations, a  

Therefore, if a small amount of potential noise drives a high-current noise between the two electrodes, the noise resistance is low. Noise resistance has been found to correlate with polarization resistance determined by EIS for certain systems [30]. 

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