Influence of Zinc Content on Corrosion Resistance of Epoxy Polyester Hybrid Powder Coatings Systems

The coatings based on zinc powders can enhance the corrosion resistance of steel substrates via two mechanisms which are known as barrier and cathodic protection. The mentioned capabilities can be evaluated using EIS technique. In this research a powder coating system based on epoxy-polyester hybrid system which contains 0, 20, 40 and 60 % of zinc was coated on carbon steel plates using Corona’s electrostatic spraying technique. The EIS and salt spray tests were used to evaluate the samples quality and performances. Almost all of mentioned tests showed that the coating with 40% zinc have better corrosion resistance. It was obviously indicated that the existence of zinc can improve the resistance properties of the coatings at an optimize content of zinc which was 40% in this system and its mechanism of protection is barrier. The coatings contains 60% of zinc had the worse result even in compared with the sample without zinc.