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With the increasing demand for Aluminum alloys, the protection of these alloys against corrosion has become important. The coatings obtained by the plasma electrolytic oxidation (PEO) method increase the corrosion resistance of the surface by providing a ceramic coating. However, these coatings are porous and their control depends on process variables such as applied current density, frequency, duty cycle, and coating application time. In this research, Aluminum alloy 5052 was subjected to PEO treatment in the phosphate bath for 2.5, 5, 7.5 and 10 minutes with the current density of 20-40 A/dm2, and the properties of the coatings were studied by polarization tests, electrochemical impedance spectroscopy and scanning electron microscopy. It has been shown that by increasing the current density at constant time, the size of the holes has increased and the PEO sample coated with the current density of 25 A/dm2 had the best corrosion resistance exhibiting a corrosion current density of 1.94×10-8A/cm2 and resistance of 189 and 53 Ω cm2 for the compact and porous layers, respectively. Also, with the increase in the coating application time, initially the holes are integrated to each other and are gradually closed, and the sample treated for 10 minutes manifested the best corrosion resistance rate of 3.04×10-9A/cm2 corresponding to 406 and 92 Ω cm2 for compact and porous layer’s resistance.

Keywords: Electrolytic Plasma Oxidation, Al5052 Alloy, Current Density Effect, Time Effect, Corrosion Resistance

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