Electrochemical Impedance Spectroscopy (EIS) of parylene coated magnesium stents in organic solvent to study early corrosion control. (1st April 2023)

• Record Type: Journal Article
• Authors: Diaz-Ramos, Margarita; Roche, Virginie; Song, Ran; Fan, Hongtao; Bureau, Christophe; Lepretre, Jean Claude
• Is Part Of: Corrosion science. Volume 213(2023)
• Publication Date: 2023-04-01
• Subjects: Magnesium -- Organic coating -- Polarization -- EIS -- Interfaces -- Oxidation; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2022.110932
• Languages: English
• ISSNs: 0010-938X

Abstract

Abstract: Layers on stents of Mg-Nd-Zn-Zr alloy, after different treatments were studied by electrochemical techniques in an organic electrolyte. Electrochemical impedance results show a constant-phase-element (CPE) behavior, which was attributed to the layers on stent surface, as well as diffusion impedance associated with Mg 2+ ions diffusion. Power law model was suggested to characterize electrical properties of the layers. Additionally, samples with oxide layers presented a high-frequency distribution which was well described by complex ohmic impedance. Compared with bare and plasma pre-treated stents, the parylene coatings showed lower capacitances values, associated with a thicker layer which is maintained after crimping and expansion. Highlights: ● Layers on stents of the Mg-Nd-Zn-Zr alloy were studied by electrochemical techniques in an organic electrolyte. ● Methodology of EIS data treatment is proposed based on the use of the Measurement Model. ● The films properties were characterised by the Power-law model and a complex ohmic impedance. ● Parylene coatings showed an improvement in substrate degradation even after crimping and expansion of the stents.