Effect of Nanoparticles on the Thermal and Mechanical Properties of Epoxy Coatings

Epoxy coatings incorporated with several nanoparticles, such as nano-SiO2, nano-Fe2O3, nanoclay and nano-TiO2, were synthesized on the surface of steel substrates by solvent sonication and room-temperature curing of fully mixed epoxy slurry. The morphologies of the epoxy nanocomposite coating were investigated using transmission electron microscopy (TEM). The effects of incorporating various nanoparticles on the thermal properties of epoxy-coated steel were investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The effect of nanoparticles on the mechanical properties of the epoxy was investigated using adhesion strength and ball impact tests. TEM results showed that the nanoparticles (especially nano-TiO2) were dispersed homogeneously into the entire volume of the resin. DSC and TGA studies revealed that nanoparticles resulted in improved cross-link density, as evidenced by the increased glass transition temperature. Nano-TiO2 increased the Tg value of the epoxy coating from 58 degrees C up to 170 degrees C. Epoxy nanocomposites modified by nano-ZnO possessed the best thermal stability. The impact test results showed that the incorporation of nanoparticles (especially nano-TiO2) can improve the impact strength the epoxy coating significantly. The adhesion strength test data show that the presence of nano-Fe2O3 particles improved the adhesion of the epoxy coatings.