STUDY OF THE CORROSION PROCESS OF A PEO-TREATED ALUMINUM ALLOY IN DIFFERENT CONCENTRATIONS OF NaCl

Yuanji Shi; Yunzhong Dai; Guoqiang Gao; Cheng Cheng; Yunyun Song

doi:10.17222/mit.2022.452

Yuanji Shi Key Laboratory of Modern Agricultural Equipment and Technology, Jiangsu University, Zhenjiang, China
Yunzhong Dai Key Laboratory of Modern Agricultural Equipment and Technology, Jiangsu University, Zhenjiang, China
Guoqiang Gao Industrial Perception and Intelligent Manufacturing Equipment Engineering Research Center of Jiangsu Province, Nanjing Vocational University of Industry Technology, Nanjing, China
Cheng Cheng College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing, China
Yunyun Song Key Laboratory of Modern Agricultural Equipment and Technology, Jiangsu University, Zhenjiang, China

DOI: https://doi.org/10.17222/mit.2022.452

Keywords: aluminum alloy, plasma electrolytic oxidation, ceramic coatings, electrochemical impedance spectroscopy, corrosion

Abstract

Plasma electrolytic oxidation (PEO) treated ceramic coatings were formed in silicate-based electrolytes without and with the addition of Al₂O₃, on an aluminum alloy. It was found that the coating produced in an electrolyte containing 7 g/L of Al₂O₃ exhibited the most superior corrosion properties. The corrosion properties of the coatings in 0.5 M and 1 M NaCl solutions were studied by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results proved that the coating can protect the substrate from the corrosion due to aggressive Cl^– in 0.5 M NaCl after 384-h immersion. However, it cannot protect the substrate after 384-h immersion in 1 M NaCl solution. The potentiodynamic polarization results matched well with the EIS test results.

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