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In this research, a vanadium based conversion coating on the aluminum 2024 alloy was applied. The effects of the most important process parameters such as pH (3, 3.5, 4, 5, 6, 7), immersion time (10, 15, 20, 25, 30 minutes), sodium vanadate concentration (5, 7/5, 10 gr/lit) and solution temperature (15, 25, 35, 45 ° C) on corrosion resistance and the morphology of the conversion coating were evaluated. Obtained results from DC (Direct polarization) and EIS (Electrochemical Impedance Spectroscopy) revealed that coated sample at the salt concentration of 10 gr/lit, pH equal to 4, room temperature and immersion time of 25 minutes had the highest anti-corrosion performance. Corrosion current density and polarization resistance for untreated substrate are 2.28 μA/cm2 and 26 kohm.cm2 respectively. These values for optimized vanadium conversion coating are 0.13 μA/cm2 and 147 kohm.cm2. The results of scanning electron microscope showed the formation of uniform convergence of vanadium conversion coating on the aluminum 2024 alloy. Based on the results of energy dispersive X-ray spectroscopy of coated sample at optimal conditions, vanadium conversion coating contains about 3 wt. % of vanadium.

Keywords: Corrosion, Vanadium conversion coating, Electrochemical impedance spectroscopy, Direct polarization, Scanning electron microscope, Energy dispersive X-ray spectroscopy, Aluminum 2024 alloy

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