Water-based & eco-friendly epoxy-silane hybrid coating for enhanced corrosion protection & adhesion on galvanized steel

It was found that due to the grafting of sol-gel coatings onto organic polymer backbone, the adhesion property and anti-corrosive performance has improved remarkably as compared to non-grafted epoxy polymer. It was observed that amino silane showed superior performance compared to thiol silane. The poor performance of thiol silane grafted epoxy coating could be attributed to some chemical incompatibility of hydrophobic and non-polar sulfur silane moiety and hydrophilic and polar waterborne epoxy polymer backbone. Addition of silane by 1 wt% and 3 wt% into epoxy polymer backbone caused improvement in both anti corrosive property and adhesion strength but further increase of the silane concentration to 5 wt% led to deterioration of protective property of the films. This drop in performance can be attributed to excessive consumption of epoxide groups in epoxy resin by amino and thiol functionalities present in silane.