On the determination of electrochemical noise resistance

The effects of sampling duration and sampling frequency on noise resistance were investigated for Type 316 stainless steel in accordance with a standard procedure employed in polarization resistance measurements. Noise resistance was also determined by wavelet transform and compared with that from AC impedance measurements. An optimum sampling duration for noise resistance determination is shown to be 600 s in comparison to the polarization resistance data, and the sampling frequency of 10 Hz is recommended in noise resistance measurements based on the level of instrumental noise and from the comparison with the polarization resistance data. After wavelet transform, the value of noise resistance for smooth coefficients in the lower level of decomposition tends to be independent of the level of decomposition, but the trend is not observed in detail coefficients. Noise resistance is suggested to be determined at a smooth coefficient with the largest level of decomposition in the independent region.