Electrochemical noise measurement ENA ASTM #1 – Corrosion – Application Note 39-1Latest updated: May 6, 2020
Noise measurements consist of recording the voltage and current fluctuations occurring when two electrodes of the same material (or not) are shorted. These measurements can lead to the determination of corrosion parameters. The fluctuations are of very small amplitude and this is why the choice of the instrument used in this purpose is critical. Efforts have been made by the American Society for Testing and Materials (ASTM) to give a procedure to characterize the measurement ability of the instrument. This second procedure involves a real electrochemical system namely a steel sample in acidic medium. A comparison of the noise resistance obtained using BioLogic instruments and by the authors lead to conclude that Bio-Logic instruments are suitable for noise measurements.
The aim of this application note is to show the ability of the Bio-logic equipment to perform reliable noise measurements that can be ultimately used to assess the corrosion characteristics of any corroding material. The procedures described below follow the ones given in the ASTM proceedings about noise measurement for corrosion applications . Our results are compared with the requirements mentioned in the ASTM publication. The Electrochemical Current Noise (ECN) is defined as the spontaneous current fluctuations occurring between two dissimilar or identical electrodes held at the same potential. These current fluctuations are due to a galvanic activity between either two dissimilar electrodes or two electrodes of the same material with microstructural differences. ECN is usually measured using a Zero Resistance Ammeter (ZRA), which connects the two working electrodes. A reference…
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