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Enhancing the Corrosion Resistance of Lightweight Mg and Al Alloys through Modified Plasma Electrolytic Oxidation Coatings: A Scanning Kelvin Probe in-situ Study

Abstract

Light metals such as Mg and Al are of high interest for lightweight engineering applications in various industries. However, their susceptibility to corrosion, poor tribological properties, and moisture sensitivity limit their direct use. Plasma electrolytic oxidation (PEO) is a commonly used process to overcome these challenges by generating ceramic-like oxide layers that significantly enhance surface protection. High-resolution in-situ atmospheric corrosion studies using a scanning Kelvin probe (SKP) were performed to evaluate the electrochemical behaviour and corrosion protection ability of PEO coatings in different humid atmospheres on AlSi7, AlMg3, and AZ801. Measurements were conducted in both nitrogen and synthetic air environment at 95% relative humidity (RH) with and without 3 wt. % NaCl electrolyte. Results showed that, for PEO-coated AlSi7 and AlMg3, scratch regions exhibited gradual stabilization or partial passivation over time, despite initial drops in Volta potential upon exposure to electrolyte or oxygen. Moreover, PEO-coated AZ80 maintained or increased its potential even when scratched down to the base metal in a chloride-rich environment indicating that the PEO layer substantially hindered cathodic reactions by limiting oxygen reduction at the defect site. Overall, these results demonstrate that PEO coatings significantly enhance corrosion protection on AlSi7, AlMg3, and AZ80 by limiting cathodic reactions. The findings highlight PEO’s potential to extend service life and reliability in demanding applications where lightweight alloys are subject to aggressive environmental conditions.

Category

Conference abstract

Language

English

Author(s)

Affiliation

  • SINTEF Industry / Materials and Nanotechnology

Year

2025

Published in

Proceedings of EUROCORR

View this publication at Norwegian Research Information Repository