Investigation on the corrosion behaviour and microstructure of 2024-T3 Al alloy treated via plasma electrolytic oxidation

• Plasma electrolytic oxidation used to improve corrosion resistance of 2024-T3 alloy.
• A conventional DC source with low applied voltage was considered for PEO.
• Use of glycerin was effective in enhancement of corrosion resistance.
• The surface morphology indicated coatings have a dense structure without cracking.
• Degradation of coatings with immersion time was investigated.

Plasma electrolytic oxidation treatment was performed on 2024-T3 aluminium alloy in a simple and inexpensive electrolyte. It was found that treatment time of 30 min resulted in the most noble corrosion potential and lowest corrosion current density. The surface and cross-sectional morphology indicated that the coating has a dense structure without any cracking. Furthermore, the result of X-ray diffraction analysis indicated that the coating was formed mainly from α-Al2O3, γ-Al2O3, Al3.21Si0.47 and small amounts of amorphous phases. The presence of glycerine in the electrolyte composition resulted in not only stabilising the solution but also improving the corrosion resistance.