Corrosion Protective Coatings: Fabrication of Sputtered CeO2-La2O3 and La2O3-CeO2 Bilayers

Abstract

This entry provides a comparative study on the corrosion protection efficiency of Ce, La films as well as Ce/La- and La/Ce-bilayered coatings deposited onto AA7075 and AA6061 substrates by the radio frequency magnetron sputtering technique. The coating thickness ranged from ~12 to 835 nm, which changed with the deposition parameters and substrate composition. The relationship between microstructure, roughness, and electrochemical performance is examined. The reactivity and crystallinity of rare earth (RE) films can be tailored by adjusting the sputtering parameters. Sputtered La films with a thickness of ~390 nm and an average roughness of 66 nm showed the best corrosion protection properties in chloride medium as determined by potentiodynamic curves and electrochemical impedance spectroscopy. The method to obtain RE-bilayered coatings, i.e., La/Ce or Ce/La as well as the substrate composition and applied power, conditioned their inhibition properties. The RE-bilayered coatings displayed better barrier properties than Ce films, which were worser than those featured by La films.