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

A Critical Appraisal of the Interpretation of Electrochemical Noise for Corrosion Studies

In this paper, procedures and parameters that enable identification of, or discrimination between, general and localized corrosion processes through electrochemical noise are critically discussed. Their relevant similarities, differences, and interdependences are indicated. In addition, the relation between different procedures and parameters with the underlying physicochemical processes is indicated. Consistent and reliable information can be obtained from electrochemical noise data when a data analysis procedure is selected, which on the one hand has a high discrimination ability and on the other hand yields a descriptive parameter that is directly associated to the underlying physico-chemical process. Procedures that meet these two requirements appear to be the Hilbert-Huang transform (Hilbert spectrum), wavelet transform (energy distribution plot), and the analysis of charge and frequency of corrosion events. In addition to the procedures that meet these two requirements, some of the descriptive parameters can be determined by different analysis procedures, which increase their reliability

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.\ud \ud The analysis procedure introduced in this work yields improved applicability of electrochemical noise measurements for the identification of an inhibition effect in corrosion processes

Transient analysis through Hilbert spectra of electrochemical noise signals for the identification of localized corrosion of stainless steel

Hilbert spectra allow identification of instantaneous frequencies that are attributed to specific corrosion mechanisms in electrochemical noise data. The present work proposes to identify and analyze areas of interest in Hilbert spectra, which enables to obtain valuable frequency information from electrochemical noise signals. Experiments were performed on AISI304 exposed to aqueous HCl solutions at different pH values resulting in either distinct general or localized attack. Results indicate that application of the proposed transient analysis to Hilbert spectra provides a significantly improved determination of the frequency characteristics of the electrochemical noise signals compared to time–frequency data analysis without transient analysis