A Comparison Between the Influence of Nano-Silica and Silane Coupling Agent on Epoxy Coatings

In order to enhance adhesion and corrosion performance of an epoxy coating, epoxy-Nano silica and epoxy-silane coatings were prepared in 0.5,1,2,3,4 and 5 wt.%, then they were applied to carbon steel substrate. Adhesion test was performed on the prepared coatings using pull off test, furthermore corrosion performance evaluated against salt spray conditions, and it was shown that there is a direct relationship between adhesion and corrosion resistance of both types of coatings. Initial temperature of decomposition (ITD) and temperature of maximum weight loss (Tmax) which obtained from thermo gravimetric analysis (TGA) of epoxy-silica coating showed a right shift to upper temperatures. Dispersion and distribution evaluation of Nano-silica in epoxy matrix was carried out using SEM images. It was found that an increase in the Nano-silica concentration is resulted in poor dispersion and distribution of nanoparticles, and consequently, the coating formed a non-uniform film with large cracks. DSC thermo grams of epoxy-silica coatings showed that incorporation of Nano-silica in epoxy matrix have several effects on the heat of reaction and kinetic of curing, so that this inorganic filler hindered curing reaction. In total, it is proved that epoxy-silica coating demonstrated better performance as a protective coating for carbon steel substrate in comparison with the epoxy-silane system.