Effects of combined surface treatments of aluminium nanoparticle on its corrosion resistance before and after inclusion into an epoxy coating

Aluminium nanoparticles were modified by cerium oxides/hydroxides in order to enhance their corrosion resistance. Then, Ce-Al nanoparticles were functionalized with 3-aminopropyltriethoxy silane (APTES) to enhance their dispersion properties and interfacial interactions. Surface chemistry of the Ce-Al nanoparticles was characterized by energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Field emission scanning electron microscopy (FE-SEM) was utilized to investigate the surface morphology of nanoparticles before and after modification by cerium nitrate. Furthermore, nanoparticles modified with APTES were characterized by Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA). The corrosion resistance of the Ce-Al, Si-Al and Si-Ce-Al samples was studied by measuring the volume of hydrogen gas evolved in an acidic solution. The effect of three types of modified nanoparticles (Ce-Al, Si-Al and Si-Ce-Al) on the corrosion protection properties of the epoxy coatings was studied by an electrochemical impedance spectroscopy (EIS). Results obtained from FE-SEM analysis revealed that the surface modified aluminium particles remained unchanged after modification with cerium nitrate in acidic solution. It was revealed that surface treatment of Ce-Al nanoparticles by APTES changed their surface nature to more hydrophobic and enhanced their dispersion properties in the epoxy coating. Deposition of Ce oxide/hydroxide layer on the nanoparticles surface was realized by XPS and EDS analyses. It was shown that surface modification by Ce film and functionalization of the nanoparticles by APTES significantly enhanced their corrosion resistance. It was shown that addition of Ce- and Si-modified nanoparticles significantly improved the corrosion protection properties of the epoxy coating. Better results were obtained when Si-Ce-Al nanoparticles were incorporated into the coating.