Two-part epoxy-siloxane hybrid corrosion protection coatings for carbon steel

A 2-part epoxy-siloxane coating cured with amino silane has been developed to provide corrosion protection on carbon steel (CRSS) using dip-coating to deposit a two layer structure. Amino silane served both as hardener, reacting with the epoxide group to initiate crosslinking, and as coupling agent to enhance adhesion of hybrid polymer resin to the metal surface. Corrosion resistance in different chemical media and mechanical properties of the coating were systematically studied and characterised. It is found that prehydrolysed amino silane can speed up drying of epoxy-siloxane coatings, touch dry coatings are obtained within 1 h. Coating materials employing a mixed solvent of ethanol and methyl ethyl ketone exhibited a longer pot life, and the resultant coatings showed no degradation of their corrosion resistance after one month chemical immersion tests in alkaline, acidic and saline conditions. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to evaluate the corrosion properties of these coatings.