Insight into physical interpretation of high frequency time constant in electrochemical impedance spectra of Mg. (15th July 2021)

• Record Type: Journal Article
• Authors: Wang, Linqian; Snihirova, Darya; Deng, Min; Wang, Cheng; Vaghefinazari, Bahram; Wiese, Gert; Langridge, Mark; Höche, Daniel; Lamaka, Sviatlana V.; Zheludkevich, Mikhail L.
• Is Part Of: Corrosion science. Volume 187(2021)
• Publication Date: 2021-07-15
• Subjects: Magnesium -- EIS -- Corrosion -- TEM -- Local measurement; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2021.109501
• Languages: English
• ISSNs: 0010-938X

Abstract

Graphical abstract: Highlights: Physical interpretation of high frequency time constant in EIS spectra of Mg was validated by calculation and experiments. Surface films on Mg in NaCl solutions with pH either 3, 5.6, or 11 were characterized by EIS measurement and TEM. In situ spatially resolved measurements clarified the formation mechanism of Mg surface film in solutions of different pH. High frequency time constant in EIS spectra of Mg originates from the barrier properties of surface film. Abstract: Electrochemical impedance spectroscopy measurements were performed to study the evolution of surface condition, which related to the high frequency time constant of Mg, in 0.05 M NaCl solution at three different pH. Based on the assumption that the high frequency time constant originates solely from the surface film, the thickness of MgO film was calculated via fitting EIS results. The deduced results were compared with the actual surface condition, characterized by transmission electron microscopy and local measurements. The results verified that the time constant at the high frequency range originates from the barrier properties of the surface film.