A study on the corrosion inhibition properties of silane-modified Fe2O3 nanoparticle on mild steel and its effect on the anticorrosion properties of the polyurethane coating

Fe2O3 nanoparticle was modified with 3-amino propyl trimethoxy silane (APTMS) to enhance its compatibility with the polyurethane coating matrix. The surface chemistry of the Fe2O3 nanoparticles was evaluated by thermal gravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. Electrochemical impedance spectroscopy (EIS) was utilized to investigate the electrochemical behavior of the steel specimens dipped in the 3.5% NaCl solutions without and with modified and unmodified Fe2O3 nanoparticles extracts. The morphology of the surface of steel samples was investigated by scanning electron microscope (SEM). Also, the polyurethane nanocomposites were prepared by addition of 2 wt% unmodified and modified nanoparticles. The effects of nanoparticles on the anticorrosion properties of the polyurethane coating were investigated with salt spray and pull-off adhesion tests. Results obtained from FTIR and TGA analyses revealed that about 5% APTMS grafted on the surface of Fe2O3 nanoparticles through physical/chemical bondings. Results obtained from EIS and SEM analyses depicted that the unmodified Fe2O3 nanoparticles showed better corrosion inhibitive performance in the extract form than other samples. However, the surface-modified Fe2O3 nanoparticles enhanced the corrosion protection properties of the polyurethane coating much greater than the unmodified Fe2O3 nanoparticles by enhancing the coating barrier performance.