Application of transient analysis using Hilbert spectra of electrochemical noise to the identification of corrosion inhibition

This study validates the ability of Hilbert spectra to investigate transients in an electrochemical noise signal for an aqueous corrosion inhibition process. The proposed analysis procedure involves the identification and analysis of transients in the electrochemical current noise signal. Their decomposition into instantaneous frequencies in a Hilbert spectrum allows detection of changes in corrosion characteristics, i.e. the evolution of corrosion inhibition with time. The effectiveness of the proposed analysis procedure is investigated for AA2024-T3 exposed to aqueous 10-1 M NaCl solutions with or without the addition of Ce ions at various concentrations. Examination of specific features in the electrochemical noise signals shows the presence of three characteristic regions, which represent surface activity regimes ranging from active (localized) corrosion to the inhibited state. Hilbert spectra of the electrochemical current noise signals allow identification of transients occurring in these successive regions. The analysis procedure introduced in this work yields improved applicability of electrochemical noise measurements for the identification of an inhibition effect in corrosion processes.