Studying the influence of nano-Al2O3 particles on the corrosion performance and hydrolytic degradation resistance of an epoxy/polyamide coating on AA-1050

The aim of this work was studying the effects of addition of Al2O3 nanoparticles on the anticorrosion performance of an epoxy/polyamide coating applied on the AA-1050 metal substrate. For this purpose, the epoxy nanocomposites were prepared using 1, 2.5 and 3.5 (w/w) pre-dispersed surface modified Al2O3 nanoparticles. Field-emission electron microscope (FE-SEM) and ultraviolet-visible (UV-Vis) techniques were utilized in order to evaluate the nanoparticles dispersion in the epoxy coating matrix. The anticorrosion performance of the nanocomposites was studied by electrochemical impedance spectroscopy (EIS) (in 3.5 wt% NaCl solution for 135 days immersion) and salt spray test for 1000 h. The coating resistance against hydrolytic degradation was also studied by optical microscope and Fourier-transform infrared spectroscopy (FTIR). Results obtained from FE-SEM micrographs and UV-visible spectra showed that the nanoparticles dispersed in the coating matrix uniformly with particle size less than 100 nm even at high loadings. Results revealed that nano-Al2O3 particles could significantly improve the corrosion resistance of the epoxy coating. Nanoparticles reduced water permeability of the coating and improved its resistance against hydrolytic degradation.