Anticorrosion efficiency of zinc-filled epoxy coatings containing conducting polymers and pigments

The dependence of the corrosion-inhibiting properties of zinc-filled organic coatings on the nature of the conducting polymers and conducting pigments added and on the pigment particles' surface coating with conducting polymer layers were investigated. The following materials were selected to examine the corrosion-inhibiting properties of the conducting polymers: polyaniline phosphate (PANI), polypyrrole (PPy), natural graphite, and carbon nanotubes. Conducting pigment combinations for application in coating materials were formulated by applying pigment volume concentrations (PVC) of 0.3%, 0.5% and 1%, which were completed with Zn dust to obtain pigment volume concentrations/critical pigment volume concentrations (PVC/CPVC) = 0.64. Such conducting pigment/zinc dust combinations represented corrosion inhibitors to be used as ingredients in protective coatings. Solvent-based 2K epoxy resin based coating materials containing the corrosion inhibitors so formulated were prepared to examine their anticorrosion properties. The pigmented coatings were subjected to laboratory corrosion tests in simulated corrosion atmospheres and to standardized mechanical resistance tests. The protective coatings so obtained exhibited a higher efficiency than coating materials containing zinc dust alone. The coating material containing carbon nanotubes at PVC = 1% and the coating material containing graphite coated with polypyrrole (C/PPy) at PVC = 0.5% emerged as the best zinc-filled coating materials with respect to their corrosion-inhibiting efficiency. Treatment with the conducting polymers had a beneficial effect on the coating materials' mechanical properties. (C) 2014 Elsevier B.V. All rights reserved.