Investigations of the synergism between cerium salt and lithium salt in the sealing of anodized film of aluminum

The synergism between cerium salt and lithium salt in the sealing of anodized film of aluminum has been investigated by using electrochemical impedance spectroscopy (EIS), scanning electron microscopy with a field-emission gun as electron source (FEG-SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy(XPS). It was revealed that the pores of anodized film of aluminum were covered with the sealing products and the corrosion resistance of the film was improved evidently by sealing process. The sealed films exhibited amorphous nature and mainly consisted of hydrous aluminum oxide and hydroxides of cerium and lithium. Some SO42- and anions of sealing solutions also existed in the films. Based on the experimental results, it could be inferred that the cerium and lithium species in the sealing solution have some kind of synergism, which can make the sealing products more compact and effectively improve the corrosion resistance of the film.