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Role of glycerine on formation & corrosion characteristic of PEO layer formed over Mg alloy in a high-concentrated mixed silicate-phosphate-based electrolyte

Jangde, A and Kumar, S and Blawert, C (2022) Role of glycerine on formation & corrosion characteristic of PEO layer formed over Mg alloy in a high-concentrated mixed silicate-phosphate-based electrolyte. In: Surface and Coatings Technology, 450 .

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Official URL: https://doi.org/10.1016/j.surfcoat.2022.128971


PEO coatings on AM50 magnesium alloy were synthesized under constant current mode exploiting high-concentrated mixed silicate-phosphate-based alkaline electrolyte with and without glycerine as an additive, i.e., gmix-PEO and bmix-PEO respectively. The development of PEO coatings was studied as a function of PEO treatment time for their microstructures, element compositions, phase compositions, and corrosion behaviour. For all the treatment times, gmix-PEO exhibited relatively smaller pores and lower coating thickness than bmix-PEO. The elemental composition of PEO coatings was independent of PEO processing time for both bmix-PEO and gmix-PEO. Throughout PEO processing the incorporation of Si was considerably higher than P into the synthesized coatings. MgO and Mg2SiO4 crystalline phase content was higher for gmix-PEO compared to bmix-PEO for all the treatment times studied. A complex amorphous oxide phase was observed from 4 min PEO treatment time for bmix-PEO while glycerine addition delayed the formation of the same. The study of electrochemical behaviour revealed improved corrosion performance of gmix-PEO particularly during initial immersion (up to 25 h) time for up to 4 min PEO treatment time than for bmix-PEO as glycerine addition leads to higher MgO and Mg2SiO4 phase content and thicker/compact inner barrier layer. For the final 8 min PEO processing time, bmix-PEO offered enhanced corrosion performance particularly due to its thicker coating compared to gmix-PEO.

Item Type: Journal Article
Publication: Surface and Coatings Technology
Publisher: Elsevier B.V.
Additional Information: The copyright for this article belongs to Elsevier B.V.
Keywords: Corrosion resistant coatings; Corrosive effects; Electrochemical corrosion; Electrochemical impedance spectroscopy; Electrolysis; Glycerol; Magnesia; Magnesium alloys; Phosphate coatings; Silicates; Silicon; Thickness measurement, Am50 mg alloy; Electrochemical-impedance spectroscopies; Mg alloy; Mixed silicate-phosphate-based electrolyte; Phase's contents; Plasma electrolytic oxidation; Potentiodynamics polarization; Processing time; Synthesised; Treatment time, Electrolytes
Department/Centre: Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited: 30 Dec 2022 10:04
Last Modified: 30 Dec 2022 10:04
URI: https://eprints.iisc.ac.in/id/eprint/78638

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