Corrosion study of a Zn–22Al–2Cu alloy coated with Y2O3

Samples of Zn–22Al–2Cu (zinalco) alloys with and without a thin film of Y2O3 were submitted to corrosion by potentiodynamic polarization and analyzed by means of X-ray photoelectron spectroscopy (XPS). In addition, corrosion current densities were measured by means of Tafel extrapolation of potentiodynamic polarization curves. After the corrosion process, all zinalco samples exhibit aluminum and zinc on the surface. Samples without the Y2O3 deposit show a depletion of aluminum on the surface, while samples with a 160-nm-thick Y2O3 film deposited by pulsed laser deposition (PLD) exhibit an aluminum-enriched surface and the formation of surface aluminum oxides. Samples with the Y2O3 deposited film and subjected to potentiodynamic polarization demonstrate an improvement in corrosion resistance up to 75% in pH=4.5 aerated water as compared with samples without the Y2O3 film.