Preparation of poly(o-ethoxyaniline)-nano SiC composite and evaluation of its corrosion resistance properties

Poly(o-ethoxyaniline) (POEA)-nano SiC composite was prepared by in situ emulsion polymerization method using dodecyl benzenesulfonic acid as the emulsifier and dopant. The structure and morphology of POEA-nano SiC composite were characterized by Fourier transformation infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy and transmission electron microscopy. The electrochemical behavior was studied by cyclic voltammetry techniques. Epoxy coatings containing SiC nanoparticles, POEA and POEA-nano SiC composite were prepared on the surface of the steel samples, and the corrosion resistance properties of the coatings were evaluated by Tafel polarization curve and electrochemical impedance spectroscopy in 3.5% NaCl solution. The results showed that the epoxy coating containing POEA-nano SiC composite exhibited higher corrosion protection and provided better barrier effects in the coating film in comparison with POEA and SiC nanoparticles. The improved corrosion resistance of POEA-nano SiC/epoxy coating may be derived from the compact structure of POEA-nano SiC composite which promoted the better compatibility with epoxy resin and decreased the pinhole deficiencies of the coating. The surface analysis of the coatings also confirmed the crack free, uniform and compact features of POEA-nano SiC/epoxy coating. The protection mechanism conferred by the pure epoxy and pigments containing coatings were also discussed.