Andréa Kalendová

By Andréa Kalendová, Tereza Hájková, Miroslav Kohl and Jaroslav Stejskal

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.

Part of the book: Conducting Polymers

By Kateřina Nechvílová, Andrea Kalendová and Miroslav Kohl

The anti‐corrosive and physical properties of organic coatings containing spinel pigments Mg0.2Zn0.8Fe2O4 wer studied. Pigments exhibiting different particle morphologies were synthesized by high‐temperature solid phase reactions. Core‐shell pigments containing Fe‐Mg‐Zn ferrite shells deposited on non‐isometric particles of mineral cores consisting of layered silicates were also prepared. The pigments were used in paints, the pigment volume concentrations in the binder being 5, 10 and 15%. Anti‐corrosive efficiency was investigated for paint films containing one of three ferro‐spinel (Mg0.2Zn0.8Fe2O4)‐based pigments or one of two core‐shell pigments consisting of Fe‐Mg‐Zn shell and lamellar silicate‐based cores. The paint properties were examined by accelerated corrosion tests and by physico‐mechanical tests. The relationships between the pigment particle shape and the paint properties were examined. The effect of the pigment particle morphology on the mechanical properties of the paint films was also investigated. The dependence of the paint film properties on the pigment volume concentration was studied and the optimum concentrations providing the most efficient anti‐corrosive protection were determined for each pigment.

Part of the book: Magnetic Spinels