TY - JOUR
T1 - Interpreting electrochemical noise and monitoring local corrosion by means of highly resolved spatiotemporal real-time optics
AU - Denissen, Paul J.
AU - Homborg, A.M.
AU - Garcia, Santiago J.
PY - 2019
Y1 - 2019
N2 - Real-time optical analysis is used to improve the interpretation of electrochemical noise signals (EN). The concept is presented for the case of AA2024-T3 under immersion in various NaCl concentrations. An in-house developed optical-electrochemical technique allowed for high spatiotemporal resolution and was used to visualize and quantify surface changes in parallel with monitoring EN signals. EN analysis was performed in the time-frequency domain using continuous wavelet transform (CWT). Correlations between the two procedures enabled the identification of corrosion processes in time, such as de-alloying, etching, pitting and subsurface corrosion. Besides this, optical measurements at higher magnification were used to analyse a smaller section of the exposed metal with a spatial resolution below 1 μm. This enabled the quantification on the size, number and nearest neighbor distance of local corrosion events, such as pits and corrosion rings. The set-up and optical protocol allowed for the first time (i) to establish a direct relationship between EN signals and the occurrence of specific localized corrosion phenomena and (ii) an in-situ highly-resolved monitoring of local corrosion processes. As a final result of the optical analysis we introduce a straightforward illustration that allows the direct identification of EN features to macroscopic local corrosion phenomena.
AB - Real-time optical analysis is used to improve the interpretation of electrochemical noise signals (EN). The concept is presented for the case of AA2024-T3 under immersion in various NaCl concentrations. An in-house developed optical-electrochemical technique allowed for high spatiotemporal resolution and was used to visualize and quantify surface changes in parallel with monitoring EN signals. EN analysis was performed in the time-frequency domain using continuous wavelet transform (CWT). Correlations between the two procedures enabled the identification of corrosion processes in time, such as de-alloying, etching, pitting and subsurface corrosion. Besides this, optical measurements at higher magnification were used to analyse a smaller section of the exposed metal with a spatial resolution below 1 μm. This enabled the quantification on the size, number and nearest neighbor distance of local corrosion events, such as pits and corrosion rings. The set-up and optical protocol allowed for the first time (i) to establish a direct relationship between EN signals and the occurrence of specific localized corrosion phenomena and (ii) an in-situ highly-resolved monitoring of local corrosion processes. As a final result of the optical analysis we introduce a straightforward illustration that allows the direct identification of EN features to macroscopic local corrosion phenomena.
UR - http://www.scopus.com/inward/record.url?scp=85073446502&partnerID=8YFLogxK
U2 - 10.1149/2.0341911jes
DO - 10.1149/2.0341911jes
M3 - Article
SN - 0013-4651
VL - 166
SP - C3275-C3283
JO - Journal of the Electrochemical Society
JF - Journal of the Electrochemical Society
IS - 11
ER -