INVESTIGADORES
CERE silvia
artículos
Título:
Hybrid Epoxy-Alkyl Sol–Gel Coatings Reinforced with SiO2 Nanoparticles for Corrosion Protection of Anodized AZ31B Mg Alloy
Autor/es:
MERINO, EMILIA; DURÁN, ALICIA; CERÉ, SILVIA; CASTRO, YOLANDA
Revista:
Gels
Editorial:
MDPI
Referencias:
Año: 2022 vol. 8
Resumen:
AZ31B Mg alloys were anodized at different potentials using an alkaline electrolyte. Then, an epoxy-alkyl silane sol reinforced with SiO2 nanoparticles was prepared by sol–gel and deposited on top of the optimized anodic layers. 1-Methyl imidazole was added to the sol to promote a partial epoxy ring aperture and improve the condensation degree of the inorganic network. The results showed the curing temperature affects the inorganic polycondensation of the organic-inorganic network; this effect was analyzed by29 Si and13 C solid-state NMR spectroscopy. Electrochemical impedance spectroscopy in 3.5 wt% NaCl solution revealed that the corrosion resistance is enhanced by the anodized process obtained for Mg alloy anodized at 100 V/2 min. However, a quick deteri-oration of the oxide film with immersion time was evident, showing a reduction of the protection efficiency (ηE%) of 76.5% after 16 h/immersion. The deposition of an epoxy-alkyl coating improved the ηE% up to 98.6% after 72 h/immersion. The proposed hybrid coating used for post-sealing the porous anodized Mg alloy looks like a good alternative protective barrier to control the corrosion process of Mg alloys. A suitable compromise between cross-linking network and curing temperature is necessary to obtain a good barrier coating.