To improve the corrosion resistance of trivalent chromium coatings

trivalent chromiumzirconium hybrid coatings were prepared on 6063 aluminum alloy by using chromic potassium sulfate and zirconium sulfate

and phosphoric acidPolarization curves and electrochemical impedance spectroscopy(EIS）were used to investigate the electrochemical characteristics of chromiumzirconium hybrid coatings formed in plating solutions of different concentrations of zirconium sulfate

and better corrosion resistance was confirmedCompared with the coatings without zirconium sulfate plating and bare aluminum alloy

polarization curves showed that the hybrid coatings formed in 08—12 g·L-1 Zr〖DK〗(SO4)2 plating solution had more positive corrosion potential

and lower corrosion current density.Electrochemical parameters of EIS indicated that the hybrid coatings had higher resistance and charge transfer resistance.The morphology and composition of the coatings were examined by SEM and EDS

respectivelyThe results showed that the morphology of coatings remained almost unchanged and the coatings mainly consisted of Cr

Zr

P

and O after addition of zirconium sulfate

and the chromiumzirconium hybrid coatings were formed on 6063 Al alloy