Anticorrosion properties of polyaniline-coated pigments in organic coatings

Four pigments of various morphology – specularite, α-Fe₂O₃; goethite, α-FeO(OH); talc, (Mg₃(OH)₂(Si₄O₁₀); and graphite, C – without and with polyaniline phosphate coating, were tested for the anticorrosion performance in coatings produced by epoxy binders on iron plates. The corrosion tests were carried out in a condenser chamber with continuous water condensation or humidity with sulfur dioxide, and in a salt mist cabinet. Polyaniline coating of pigments in all cases improved the anticorrosion properties. Graphite coated with polyaniline performed the best among eight systems under investigation. The role of graphite and polyaniline conductivity in the electron transfers associated with corrosion of iron has been proposed.