Investigation on Aluminum AA2024-T6's Corrosion Behavior Coated by Plasma Electrolytic Oxidation in Maritime Media

In this study، Plasma Electrolytic Oxidation (PEO) technique was used for generating ceramic layer on the surface of aluminum alloy AA2024-T6; and the effect of coating time on the electrochemical corrosion behavior، micro-hardness، morphology of coating، and the phase structure was studied. The alloy was coated in 1، 3، 5 and 7 minutes at a constant electrical potential 550 V in a sodium silicate solution 30 g/l. Coating surface morphology was studied by Scanning Electron Microscopy (SEM); and the electrochemical corrosion behavior was investigated by potentiodynamic and Electrochemical Impedance Spectroscopy (EIS) tests in 3. 5 %wt. NaCl solution. Phases that generated during coating process were studied by X-Ray Diffraction (XRD) and hardness of coating was investigated by micro-hardness test. The results revealed that، as the coating time increases، the hardness value increases too. But، since the sample coated for 5 minutes exhibit the best morphology، it has shown the maximum corrosion resistance.