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In the present investigation, the plasma electrolytic oxidation (PEO) process was employed to form aluminum oxide coating layers to enhance corrosion resistance properties of high-strength aluminum alloys. The formed protective coating layers were examined by means of scanning electron microscopy (SEM) and characterized by several electrochemical techniques, including open circuit potential (OCP), linear potentiodynamic polarization (LP) and electrochemical impedance spectroscopy (EIS). The results were reported in comparison with the bare 6061-O aluminum alloy to determine the corrosion performance of the coated 6061-O alloy. The PEO-treated aluminum alloy showed substantially higher corrosion resistance in comparison with the untreated substrate material. A relationship was found between the coating formation stage, process parameters and the thickness of the oxide-formed layers, which has a measurable influence on enhancing corrosion resistance properties. This study demonstrates promising results of utilizing PEO process to enhance corrosion resistance properties of high-strength aluminum alloys and could be recommended as a method used in industrial applications.

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AZ31 alloy is used as a lightweight material for structural application in the automobile and aircraft production. However, alloy AZ31 is known to have poor corrosion resistant due to high electrochemical activity. In this study, the possibility of improving the corrosion resistance by applying protective coatings deposited by the low pressure cold spray process was investigated. The relative performance of each cold sprayed corrosion preventive coatings was assessed in accordance with American Society for Testing and Materials standards. The data for the bare AZ31 alloy were initially obtained and used as a reference point to compare the corrosion protective performance of different preventive coatings. Electrochemical behaviour of each coating composition was analyzed after a given time period of the accelerated corrosion test. Microstructure and mechanical properties of the deposited preventive coatings are also discussed. The cold sprayed preventive coatings provide sufficient protection to substantially reduce the corrosion rate of alloy AZ31.