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

Zinc-rich primers due to their unique properties are commonly used to protect steel substrates in different corrosive environments such as marine and industrial environments.Zinc-rich primers use two mechanisms, barrier and cathodic protection, for preventing from iron corrosion. The electrical conductive routes between zinc powder inside of the coating and under the iron substrate, i.e. Percolation, are one of the main parameters for zinc-rich primers. Due to evaporatingorganic materials to atmosphere, solvent-based coatings are recently replaced by environment friendly coatings like zincrich powder coatings. Moreover, the zinc content of the mentioned material is in the range between 10 and 70 percent of the weight. The EIS method is commonly used for the evaluation of protective properties of anti-corrosive organic coatings and for indicating the mechanism of corrosionprotection. Barrier and galvanic protection can be controlled by using EIS and by controlling low frequency impedanceduring the immersion time in 3.5 percent sodium chloride solution. In the present study, the performance of powder primers containing different amount of zinc with the base ofepoxy-polyester hybrid resin is studied by using EIS and salt spray methods. We studied the effect of zinc percent on the performance of the mentioned coatings.