MAURILIO PEREIRA GOMES
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Artigo IPEN-doc 29040 A new look on the corrosion mechanism of magnesium2022 - BENBOUZID, ABDELMOHEIMAN Z.; GOMES, MAURILIO P.; COSTA, ISOLDA; GHARBI, OUMAIMA; PEBERE, NADINE; ROSSI, JESUALDO L.; TRAN, MAI T.T.; TRIBOLLET, BERNARD; TURMINE, MIREILLE; VIVIER, VINCENTThis study investigates the electrochemical impedance diagrams obtained for a Mg electrode in a sodium sulphate solution at different pHs. A comprehensive model, independent of the pH range, with the presence of two adsorbed intermediates accounting for the anodic dissolution and the cathodic reaction was proposed to explain the singular behaviour of Mg at low pH values. It was also shown that, in acidic media, the contribution of the double layer as well as the cathodic partial reaction must be considered, whereas at higher pH values the oxide/hydroxide layer plays a significant role and slows down the magnesium corrosion rate.Artigo IPEN-doc 25807 On the corrosion mechanism of Mg investigated by electrochemical impedance spectroscopy2019 - GOMES, MAURILIO P.; COSTA, ISOLDA; PEBERE, NADINE; ROSSI, JESUALDO L.; TRIBOLLET, BERNARD; VIVIER, VINCENTThis 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 ðMgþ ads Þ 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.