Application of electrochemical noise (EN) technology to evaluate the passivation performances of adsorption and film-forming type corrosion inhibitors

Electrochemical noise (EN) technology is an accurate, non-destructive, and rapid method for evaluating corrosion protection performance that has been undergoing development for the last decade. In this work, EN was applied to detect the inhibitor type and evaluate the short-term (12 h) and long-term (30 d) passivation performances. The results indicated that the EN signal amplitude and the noise resistance (Rn) value significantly increased after adding inhibitors, which could be utilized to identify the existence of the inhibitors. The shot noise and the energy distribution results exhibited different characteristics with the variation of the corrosion types in the presence of the different types of inhibitors. Rn showed a positive relationship with the polarization resistance and was inversely proportional to the corrosion current during a long-term passivation process. The EN results were verified by electrochemical impedance spectroscopy, potentiodynamic polarization curves, and surface morphology analysis. These results provided a theoretical foundation for the application of the EN technology to evaluate passivation performances of corrosion inhibitors.