Characterization of corrosion inhibition performance of azole compounds through power spectral density of electrochemical noise

• Benzotriazole and benzothiazole inhibited the stainless steel corrosion in 1 M H2SO4.
• Electrochemical noise analysis of effectiveness of the inhibitors in 1 M H2SO4.
• Finding correlation between the distribution of PSD energy and corrosion intensity.
• Introducing an approach to determine minimum frequency domain for the q calculation.

The power spectral density was focused to analyze the electrochemical noise data of stainless steel samples dipped in 1 M H2SO4 solution without and with different concentrations of benzotriazole and benzothiazole corrosion inhibitors. Accordingly, a good correlation was observed between corrosion intensity and PSD (I) and PSD (V) distributions calculated for each frequency point as a percentage of total energy, over the frequency domain. In addition to indicating the inevitable role of PSD distribution in determining characteristic charge from shot noise theory, an approach was developed to choose minimum frequency range to calculate q, in particular for the systems with different types of PSD distributions.