Corrosion behavior of rare earth cerium based conversion coating on aluminum alloy

The present paper focused on the use of the salt of rare earth cerium as corrosion inhibitor of aluminum by using cathodic electrolytic passivation method. The corrosion resistance and the microphology of the cerium passivation film were studied by the methods of electrochemical method, scanning electron microscopy (SEM), and energy dispersive spectroscopic analysis. From the results, it was shown that good corrosion resistance of cerium-based passive coating was obtained when the compositions were as follows: CeCl₃·7H₂O, 0.05 mol/L; H₂O₂, 30 ml/L; current density, 1.1 mA/cm²; temperature, 40 °C; time, 9 min. SEM and EDS revealed that the cerium conversion coatings formed on the surface of aluminum alloy were related to cerium hydroxide/hydrated oxide depositions.