Optimal conditions for the deposition of novel anticorrosive coatings by RF magnetron sputtering for aluminum alloy AA6082

Highlights: • Non-conventional technique for improving the corrosion resistance of aluminum alloys. • Effect of the deposition parameters: power, substrate temperature and deposition time. • Changes in the crystallinity of the coatings are observed with the temperature. • The structure of these coatings is found to be dependent on the nature of the substrate. • La coatings can provide a better physical barrier to inhibit the corrosion attack. - Abstract: Cerium and lanthanum coatings were deposited on glass, silicon (1 0 0), and aluminum alloy by RF magnetron sputtering in which several experimental conditions such as power, substrate temperature, and deposition time were varied, using pure CeO₂ and La₂O₃ targets. The effect of deposition parameters on the bonding structure, surface morphology and properties against corrosion of rare earth (RE) coatings formed on metallic substrate was reported. The microstructure and chemistry of the thin film were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and X-ray photoelectron spectroscopy (XPS); whereas their use as corrosion resistant coatings was studied in aqueous NaCl solution (3.0 wt%) by using polarization curves. Variations in these properties were observed by increasing the substrate temperature which modifies the crystallinity of the rare earth coatings. XRD and XPS findings indicate that the cerium coatings are composed by CeO₂ and a significant quantity of Ce₂O₃ due to oxygen deficiency in the sputtering chamber, whereas La₂O₃/La(OH)₃ and some La intermetallic compounds are detected in the lanthanum films. Variations in the E_corr and I_corr were found as a function of the thickness, texture, and morphology of the as-prepared coatings