Evaluation of the Mechanical and Anticorrosion Properties of PU-SiC Nanocomposite Coatings

In this research the effect of silicon carbide nanoparticles and surface pretreatment on the mechanical properties and corrosion protection properties of the polyurethane coatings (40 μm in thickness) were studied on a low carbon steel substrate. The substrates were prepared by polishing and sand blasting methods. Dispersion of the nanoparticles in the polyurethane coating was studied by field emission scanning electron microscope (FE-SEM) image and X-ray diffraction (XRD) analysis. The physical and mechanical properties of the coatings were evaluated by pull-off adhesion، Tubular impact and pencil hardness tester. The Electrochemical Impedance Spectroscopy (EIS) and polarization tests were employed in order to investigate the corrosion resistance behavior of the coatings. The effect of nanoparticles on the chemical bonding of polyurethane were investigated using Fourier Transform Infrared Spectrometry (FT-IR) Analysis. The results of the physical and mechanical study showed that the existence of 2 wt% of nanoparticles، leads to the increase of the adhesion strength up to 50%، hardness of coating increased from 3H to 5H and impact resistance were increased about 34 %. In addition، the results of electrochemical test showed that the existence of 2 wt% of nanoparticles in polyurethane did not significantly change the corrosion resistance behavior of the polyurethane. The results of field emission scanning electron microscope (FE-SEM) image and X-ray diffraction (XRD) analysis showed that nanoparticles up to 2 wt% were well dispersed in polyurethane. Sand blasting of the specimens prior to coating increased adhesion strength up to 35%، but decreased the impact resistance in compare with polishing. J. Color Sci. Tech. 9 (2015)، 239-250©. Institute for Color Science and Technology.