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 potential use in biomedical implants. However, their poor corrosion resistance in physiological fluids restricts practical applications. Cerium-based coatings have been studied as an environmental friendly option to enhance the corrosion resistance of magnesium alloys. In order to control the biodegradation rate of AZ91D magnesium alloy in simulated physiological solution, the formation of a coating from a solution containing cerium nitrate (Ce(NO3)3) was studied. The effect of different additives in the treatment solution (ascorbic acid, citric acid, and sodium citrate) on the anticorrosive properties of the coatings was evaluated. The characterization of the coatings was done using electrochemical techniques and SEM/EDS, XRD, and XPS analyses. The corrosion properties were examined in Ringer solution by polarization studies, open circuit measurements, and faradaic impedance spectroscopy. Results showed that the incorporation of additives improves the anticorrosive properties of the Ce-based film. The coating modified with ascorbic acid provides the best corrosion resistance. According to XPS results, the film is mainly composed by Mg oxides or hydroxides and Ce oxides.
Part of the book: Cerium Oxide
Interest in cerium-based coatings has increased in recent years due to their low toxicity, biocompatibility, and improved corrosion protection performance. The formation of a coating from a solution containing cerium nitrate (Ce(NO3)3) has been investigated as a good surface modification strategy for the production of protective coatings on 316L SS. The effect of various additives in the treatment solution (sodium molybdate, sodium salicylate, and ascorbic acid) on the corrosion protection properties of the coatings was evaluated. The protection performance of the coated samples in a physiological simulated fluid (Ringer solution) was examined by electrochemical methods. The composition and morphology of all coatings were analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX).
Part of the book: New Advances in Steel Engineering