Organic coatings containing polyaniline and inorganic pigments as corrosion inhibitors

Polyaniline (PANI) was synthesized by chemical oxidative polymerization in laboratory conditions. The main objective was to study the properties of organic coatings containing PANI and PANI in combination with other anti-corrosive pigments. The adhesion, barrier, and anti-corrosion properties of the coatings containing PANI and selected chemically active pigments were studied as well as the combination of PANI with zinc dust. Epoxy resin of bisphenol type hardened with a polyamine-based curing agent was used as a binder. In order to examine the synergic effect of PANI and anti-corrosion pigment in epoxy coatings, Zn3(PO4)2·2H2O with an acidic aqueous extract, Ca3(BO3)2 with a basic aqueous extract and SrCrO4 with a neutral aqueous extract have been tested.The comparison of the results of corrosion tests completed in the atmosphere of SO2 and of NaCl revealed that the PANI + Zn3(PO4)2·2H2O combination increased the anti-corrosion efficiency of organic-coatings. Both these pigments display the acidic pH of the aqueous extract, which may lead to very high anti-corrosion efficiency. The investigation of the total anticorrosion efficiency of coatings with the PANI + Zn-dust combination found out that the PANI combination with a volume concentration (PVC) of 5% and Zn-dust (PVC/CPVC = 0.65) achieves high anticorrosion efficiency.