Fluoropolymer/SiO2 encapsulated aluminum pigments for enhanced corrosion protection

Abstract

Flake aluminum powders with excellent corrosive resistance properties are attractive materials in many technological applications. Here, a convenient strategy is employed to encapsulate the aluminum powders by using silicon-fluoropolymer composite film, by which the chemical resistance of aluminum-based pigments is significantly improved. A basic layer of SiO2 is formed on the surface of the flake aluminum powders via sol-gel process. For the good compatibility between the silicon and fluorine, a uniform and dense layer of poly (trifluoroethyl methacrylate) (PTFEMA) is pasted tightly on the silicon layer initially formed by solution polymerization. Protected by this kind of composite silicon-fluoro-layer, the encapsulated aluminum powders were highly stable when they dipped into strongly alkaline solution (1.25 M, pH > 14). The morphology of composite layers on the aluminum powders are characterized by means of scanning electron microscopy (SEM). The structures of silicon-fluoropolymer composite film are tested by Fourier transform infrared spectroscopy (FTIR), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The relationship between the usage of monomers and cross-linker on corrosion inhibition properties is systematically investigated. The phenomenon of hydrogen gas evolution is eliminated by the PTFEMA/SiO2 hybrid films owing to an efficient fluorinated protective film on aluminum pigments.