On the corrosion mechanism of Mg investigated by electrochemical impedance spectroscopy

Author(s)

Gomes, Maurilio Pereira ^{[1, 2]} ; Costa, Isolda ^[2] ; Pebere, Nadine ^[3] ; Rossi, Jesualdo Luiz ^[2] ; Tribollet, Bernard ^[1] ; Vivier, Vincent ^[1]

Affiliation

^[1] Sorbonne Univ, CNRS, LISE, F-75005 Paris - France

^[2] Ctr Ciencia & Tecnol Mat, Inst Pesquisas Energet & Nucl, Ave Prof Lineu Prestes, 2242, Cidade Univ, BR-05508000 Sao Paulo, SP - Brazil

^[3] Univ Toulouse, CIRIMAT, CNRS, INPT, UPS, ENSIACET, 4, Allee Emile Monso, BP 44362, F-31030 Toulouse 4 - France

• Document type: Journal article
• Source: Electrochimica Acta; v. 306, p. 61-70, MAY 20 2019.
• Web of Science Citations: 5

Abstract

This work reported a detailed analysis of the electrochemical impedance spectra obtained for the Mg electrode during immersion in a sodium sulfate solution. A model was proposed which took into account the presence of: (i) a thin oxide film (MgO) which progressively covered the Mg electrode surface, (ii) film-free areas where the Mg dissolution occurs in two consecutive steps, (iii) a thick layer of corrosion products (Mg(OH)(2)), (iv) an adsorbed intermediate oMg thorn ads thorn which is responsible for the chemical reaction allowing the negative difference effect to be explained. From the impedance data analysis, various parameters were extracted such as the thin oxide film thickness, the resistivity at the metal/oxide film interface and at the oxide film/electrolyte interface, the active surface area as a function of the exposure time to the electrolyte, the thickness of the thick Mg(OH)(2) layer and the kinetic constants of the electrochemical reaction. (c) 2019 Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 13/13235-6 - Investigation on the localized corrosion and the fatigue corrosion resistance of high strength aluminum alloys joined by friction stir welding (FSW)
• Grantee: Isolda Costa
• Support Opportunities: Research Projects - Thematic Grants