The Electrochemical Corrosion Behavior of Plasma Electrolytic Oxidation Coatings Fabricated on Aluminum in Silicate Electrolyte

• Published in: Journal of materials engineering and performance 2019-06, Vol.28 (6), p.3652-3660
• Main Authors: Yang, Zhong, Wang, Rui-qiang, Liu, Chen, Wu, Ye-kang, Wang, Dong-dong, Liu, Xin-tong, Zhang, Xu-zhen, Wu, Guo-rui, Shen, De-jiu
• Format: Article
• Language: English
• Subjects: ALUMINIUM; Characterization and Evaluation of Materials; Chemistry and Materials Science; COATINGS; Corrosion and Coatings; CORROSION PRODUCTS; CORROSION RESISTANCE; ELECTROCHEMICAL CORROSION; ELECTROCHEMISTRY; ELECTROLYTES; Engineering Design; HYDROGEN IONS 1 PLUS; MATERIALS SCIENCE; OXIDATION; OXIDES; PITTING CORROSION; PLASMA SWITCHES; Quality Control; Reliability; Safety and Risk; SCANNING ELECTRON MICROSCOPY; SILICATES; SODIUM CHLORIDES; Tribology; X-RAY SPECTROSCOPY
• ISSN: 1059-9495; 1544-1024
• DOI: 10.1007/s11665-019-04099-8

Plasma electrolytic oxidation (PEO) coatings were fabricated on the aluminum in silicate electrolyte. Microstructures and elemental compositions of these PEO coatings were examined by scanning electron microscopy (SEM) equipped with an energy-dispersive x-ray spectroscopy (EDS). Corrosion resistances of the coated samples were evaluated using the measurements of open-circuit potential (OCP), repetitive polarization and electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl solution. The results indicated that the PEO coatings not only act as a physical shield limiting the penetration of corrosive solution, but also establish an anodic location with high concentration of H + ions and other product ions as pitting corrosion begins. With the development of pitting corrosion, the accumulation of corrosion products inside the pits and pores of the coatings decreases the corrosion process effectively.