Corrosion behavior of aluminum oxide coatings created by electrolytic plasma method under different potential regimes

The electrolytic plasma coating is affected by various factors such as electrolyte conductivity, voltage, and current. However, there has not been much attention to the effect of the current regime. The main objective of the present study is to investigate the potential of Al۲O۳ coatings deposited by the electrolytic plasma method. Aluminum Series ۲ was used in this study and the electrolyte was composed of sodium silicate, sodium tetraphosphate, sodium aluminate and potassium hydroxide. The results showed that, in general, according to the impedance diagrams, the corrosion resistance of the coated specimens greatly increases with the immersion time. Therefore, the unit of resistance increased on average to about ۱۰ MHz after ۷۲ hours. In the case of pulsed potential application regime, the corrosion behavior of the samples in the working cycle of ۳۰% was better than that of ۷۰%, which can be related to the thickness of the formed coatings and their porosity. This allows the coating to degrade the coating faster by increasing the thickness and decreasing the porosity of the aggressive chloride ion.

Keywords:

Plasma electrolytic oxidation , Aluminum oxide coatings , Potential regime , Corrosion