Cerium Oxides for Corrosion Protection of AZ91D Mg Alloy

ANA PAULA LOPERENA; IVANA LETICIA LEHR; SILVANA BEATRIZ SAIDMAN

Cerium Oxide - Applications and Attributes

IntechOpen

Lugar: Londres; Año: 2019; p. 23 - 41

Die-cast AZ91D magnesium alloy (8.9 wt.% Al, 0.6 wt.% Zn, 0.2 wt.% Mn, and balance Mg),as novel alternative biodegradable material, has received great attention due to their potentialuse in biomedical implants. However, their poor corrosion resistance in physiological fluidsrestricts practical applications. Cerium-based coatings have been studied as an environmentalfriendly option to enhance the corrosion resistance of magnesium alloys. In order to controlthe biodegradation rate of AZ91D magnesium alloy in simulated physiological solution, theformation of a coating from a solution containing cerium nitrate (Ce(NO3)3) was studied. Theeffect of different additives in the treatment solution (ascorbic acid, citric acid, and sodiumcitrate) on the anticorrosive properties of the coatings was evaluated. The characterizationof the coatings was done using electrochemical techniques and SEM/EDS, XRD, and XPSanalyses. The corrosion properties were examined in Ringer solution by polarization studies,open circuit measurements, and faradaic impedance spectroscopy. Results showed that theincorporation of additives improves the anticorrosive properties of the Ce-based film. Thecoating modified with ascorbic acid provides the best corrosion resistance. According to XPSresults, the film is mainly composed by Mg oxides or hydroxides and Ce oxides