Improving the Corrosion Resistance of Wrought ZM21 Magnesium Alloys by Plasma Electrolytic Oxidation and Powder Coating

Lavanya Rani Ballam; Hamed Arab; Massimiliano Bestetti; Silvia Franz; Giulia Masi; Ramona Sola; Lorenzo Donati; Carla Martini

doi:10.3390/ma14092268

Materials (Apr 2021)

Improving the Corrosion Resistance of Wrought ZM21 Magnesium Alloys by Plasma Electrolytic Oxidation and Powder Coating

Lavanya Rani Ballam,
Hamed Arab,
Massimiliano Bestetti,
Silvia Franz,
Giulia Masi,
Ramona Sola,
Lorenzo Donati,
Carla Martini

Affiliations

Lavanya Rani Ballam: Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, 20133 Milan, Italy
Hamed Arab: Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, 20133 Milan, Italy
Massimiliano Bestetti: Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, 20133 Milan, Italy
Silvia Franz: Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, 20133 Milan, Italy
Giulia Masi: Department of Civil, Chemical, Environmental and Materials Engineering, University of Bologna, 40131 Bologna, Italy
Ramona Sola: Department of Industrial Engineering, University of Bologna, 40136 Bologna, Italy
Lorenzo Donati: Department of Industrial Engineering, University of Bologna, 40136 Bologna, Italy
Carla Martini: Department of Industrial Engineering, University of Bologna, 40136 Bologna, Italy

DOI: https://doi.org/10.3390/ma14092268
Journal volume & issue: Vol. 14, no. 9
p. 2268

Abstract

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Plasma Electrolytic Oxidation (PEO) was applied to extruded ZM21 Mg alloys to improve their corrosion resistance in a chloride-containing environment. PEO was carried out in DC mode and voltage control in a fluoride-free electrolyte. Potentiodynamic polarization tests in 3.5 wt.% NaCl aqueous solution and neutral salt spray (NSS) tests were carried out. Microstructural and profilometric characterization, as well as NSS tests were performed in different conditions: (i) bare ZM21, (ii) PEO-treated ZM21, (iii) powder-coated ZM21 (without PEO interlayer), and (iv) PEO-treated ZM21 with powder coating top layer (carboxyl-functionalized polyester resin). The PEO + powder coating double layer was identified as the best-performing corrosion protection.

Published in Materials

ISSN: 1996-1944 (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Technology: Electrical engineering. Electronics. Nuclear engineering; Technology: Engineering (General). Civil engineering (General); Science: Natural history (General): Microscopy; Science: Physics: Descriptive and experimental mechanics
Website: http://www.mdpi.com/journal/materials/

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