Micro-arc oxidation coatings were formed on a TC4 surface with different Bi2S3 concentrations (0-0.2g·L-1). The influences of Bi2S3 on the micro-structure, phase composition, and corrosion resistance ofthe prepared coatings were investigated by scanning electron microscopy (SEM), X-ray diffraction(XRD), X-ray photoelectron spectroscopy (XPS), and electrochemical workstation. In this research, theMAO voltage first increases and then decreases with an increasing Bi2S3 concentrations, which resultsin similar changes in the thickness and hardness of the coating. XRD and XPS results show that thephase composition of the coating mainly consists of rutile, anatase and Bi2O3. The combined result ofan increased coating thickness and the presence of anatase promotes coating densification, therebyincreasing the corrosion resistance of the coating. Electrochemical polarization curve and impedanceresults show that the coating has the best corrosion resistance when the Bi2S3 concentration is 0.1 g·L-1.Therefore, the addition of Bi2S3 optimizes the microstructure of the MAO coating and enhances itscomprehensive properties..
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