Factors Affecting the Determination of Electrochemical Noise Resistance

The similarity between electrochemical noise resistance (R_n) and polarization resistance (R_p) has been confirmed in many laboratories, and a new method for corrosion rate determination has been developed based upon this similarity. However, this method remains controversial. Some researchers have reported experimental results that did not support a similarity between R_p and R_n. Other researchers have found that this similarity does not hold true for every system. To address this controversy, factors affecting the measurement and calculation of R_n were investigated. Several factors — including instrument noise, direct current (DC) trend, noise sampling rates, and noise sampling duration — can affect the accuracy of R_n determination significantly and, in some cases, can cause disagreement between R_n and R_p. It was recommended that a system check be carried out to avoid the influence of these factors.