Cerium oxides microstructure

The metal surface is covered with cerium oxide and the thickness of the film increases with time of immersion of the sample in the CeCl3 solution. Deposition and growth of islands of rare earth oxide have been observed. The islands may be associated with anodic and cathodic sites located in the microstructure of the metal. 

Deposition effects of rare earth oxides on the surfaee of iron and stainless steels have also been reported [58]. The eorrosion rate eonstants decreased significantly by the coating in corrosion tests under isothermal eonditions. In thermal cyclic conditions, protective scale spallation completely disappeared for eoated samples. The rare earth effect is more remarkable with elements located on the left part of the lanthanide series (lighter rare earths). For example, eeria coatings strongly modify the microstructure and texture of the wustite (FeO) scale formed during low pressure oxidation of pure iron [59]. Cerium is located in the wustite matrix as a CeFeOs phase which dissolves in FeO in time. 

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