Effect of Concentration of Al۲O۳ Particles in Plating Bath on Microstructure and Corrosion Behavior of Zn-Co-Al۲O۳ Composite Coating

Metal-based composite coatings with ceramic particles can be used to improve the mechanical and corrosion properties of steels. In this research, Zn-Co-Al۲O۳ composite coating was applied on st۳۷ steel substrate by electroplating method. The microstructure and corrosion behavior of the coating was investigated by changing the concentration of alumina particles in the bath. Coating was done at concentrations of ۵۰, ۶۰, ۷۰, ۸۰, ۸۵ and ۹۰ g/l of alumina. A scanning electron microscope (SEM) was used to investigate the microstructure and observe the morphology. In order to evaluate the corrosion resistance, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests were carried out for both coated and uncoated samples in ۳.۵% NaCl. Microstructure analysis showed that the best concentration of alumina for precipitation is ۷۰ g/l, and in this concentration, coating had good adhesion, least uniformity and no crack. The results of Tafel polarization and Electrochemical Impedance Spectroscopy tests were also consistent with the microscopic images and showed that the coating formed in the bath with a concentration of ۷۰ g/l of alumina has the highest corrosion resistance

کلیدواژه ها:

Zn-Co-Al۲O۳ composite coating ، concentration ، corrosion ، potentiodynamic polarization ، electrochemical impedance spectroscopy ، پوشش کامپوزیتی Zn-Co-Al۲O۳ ، غلظت ، خوردگی ، پلاریزاسیون پتانسیودینامیک ، طیف نگاری امپدانس الکتروشیمیایی