from the conferences organized by TANGER Ltd.
Plasma electrolytic oxidation (PEO) technique is a process of surface treatment of light metallic materials such as magnesium alloy, to produce coatings increasing the corrosion resistance. In this work, the effect of direct or alternating current deposition mode on the structure and corrosion behavior of PEO coatings on Mg substrates prepared by powder metallurgy (PM) was studied. It was observed that during the deposition process of PEO coatings, the varying of current mode between alternating current (AC) and direct current (DC) led to significantly different surface modifications and coatings properties. In the case of DC PEO coatings, significantly higher thickness was achieved than in the case of AC PEO coatings. On the other hand, AC PEO coatings achieved smaller pore sizes compared to the DC PEO coatings. Considering the denser and less porous structure of AC PEO coating, significantly better electrochemical properties were observed using potentiodynamic measurements in Hank's solution. Compared to the uncoated PM Mg substrate, there was an order of magnitude decrease in the icorr of PEO-coated Mg substrate. In the case of DC PEO coatings, the icorr value was determined to be 8.3 µA·cm-2, and in the case of AC PEO even 3.4 µA·cm-2.
Keywords: Magnesium, powder metallurgy, PEO coating, corrosion, Hank’s solution© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.