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The effect of vanadia surface treatment on the corrosion inhibition characteristics of an advanced magnesium Elektron 21 alloy in chloride media

Abstract:

An advanced magnesium Elektron 21 alloy has recently been developed as a possible alternative to aluminum and steel based alloys for transportation industries. The newly developed Elektron 21 alloy characterises with its high corrosion resistance in chloride solution, excellent mechanical properties and light weight. Our group has recently developed high performance vanadia protective coatings of self-healing functionality that have been used to improve the surface resistance of different magnesium and aluminum alloys. This paper addresses an attempt to make functionality of the vanadia coatings we designed to improve the corrosion resistance of the newly developed Elektron 21 alloy in corrosive environment. The corrosion inhibition characteristics of Elektron 21 alloy were studied at different vanadia solution concentrations namely 10, 30 and 50 g/l at the neutral vanadia solution pH. Electrochemical impedance spectroscopy was used to evaluate the electrochemical behavior in 3.5% NaCl. Results confirmed the acceptable pitting corrosion resistance of Elektron 21 alloy. However, crevice and general corrosion were observed. Unlike all previous Mg and Al alloys we studied, vanadia coatings has an adverse effect on the corrosion protection of Elektron 21 alloy due to formation of inhomogeneous coating of mixed oxides of neodymium, gadolinium, zirconium in addition to vanadia as identified by SEM-EDS. © 2012 by ESG.