Properties of Metal Oxide Pigments Surface Modified with Polyaniline Phosphate and Polypyrrole Phosphate in Corrosion Protective Organic Coatings

Abstract

The objective of this work was to describe the properties of metal oxide-based pigments whose surface has been coated with a conductive polymer, if used as pigments in organic coating materials. The perovskite-type pigments were synthesized by high-temperature solid-phase reaction, and their surface was modified with a conductive polymer, specifically polyaniline phosphate or polypyrrole phosphate, by chemical oxidative polymerization. The pigments' structure and physicochemical properties were examined by XRD, XRF, and SEM. The composite pigments (pigment/ conductive polymer) were dispersed in a solvent-type epoxy-ester resin binder to obtain a series of paints whose anticorrosion properties were assessed by means of corrosion tests in simulated corrosion atmospheres and by the linear polarization method. The anticorrosion and mechanical properties of the paints were compared with those of a paint containing the routinely used zinc phosphate hydrate pigment as a reference material. The pigments were found to possess a high anticorrosion efficiency, comparable to or higher than that of the commercially available zinc phosphate-based anticorrosion pigment. The highest anticorrosion efficiency was observed with the paints containing the Ca-Ti, Sr-Ti, and Sr-Mn perovskite pigments modified with polypyrrole phosphate.