Incorporation of Al(2)O(3), GO, and Al(2)O(3)@GO nanoparticles into water-borne epoxy coatings: abrasion and corrosion resistance

Nano-Al(2)O(3) particles and graphene oxide (GO) nanosheets were modified by 3-aminopropyltriethoxysilane (KH550), and then dispersed in epoxy resin, and finally modified-Al(2)O(3)/epoxy, modified-GO/epoxy and modified-Al(2)O(3)@GO/epoxy composite coatings were prepared on steel sheets by the scraping stick method. The microstructure, phase identification, surface bonding and composition of the nanoparticles were characterized by SEM, XRD, FT-IR, and Raman spectroscopy, respectively. The hardness of the coating was assessed by the pencil hardness method. The abrasion resistance of the coating was tested by a sand washing machine. The corrosion resistance of the coating was assessed using salt spray, a long-period immersion test, potentiodynamic polarization curves and electrochemical impedance spectra. With the addition of a small amount of nanoparticles, the dispersion of nanoparticles in the epoxy resin was good. When the content of nano-Al(2)O(3) particles was equal to 1.5 wt%, the particles in the epoxy exhibited the best dispersion and stability. However, the GO and Al(2)O(3)@GO nanofillers in the epoxy resin exhibited poor dispersion and stability. The hardness, abrasion and corrosion resistance of the composite coatings were improved with the addition of a small amount of nanoparticles, but the performance began to decline after exceeding a certain content range of the nanoparticles. A relatively good abrasion resistance for the coatings was obtained when the content of Al(2)O(3), GO and Al(2)O(3)@GO after modification was 1.5 wt%, 0.2 wt% and 0.4 wt%, respectively. The corrosion resistance of the coatings doped with nano-Al(2)O(3) particles was better than that of the coatings incorporating GO nanosheets and Al(2)O(3)@GO hybrids. The corrosion mechanism of the composite coatings in 3.5 wt% NaCl solution was addressed and studied.