Cerium modified minerals for eco-friendly anticorrosive paints

SOL ROSELLI; MARIANA V. REVUELTA; ALEJANDRO DI SARLI; MARTA DEYÁ; ROBERTO ROMAGNOLI

Estoril

Congreso; Eurocorr 2013 European Corrosion Congress; 2013

European Federation of Corrosion

Zinc phosphate and related compounds are widespread anticorrosive pigments for paints. They became the leading substitutes for chromates and lead compound, both of very high toxicity. However environmental regulations are focusing on limiting the incorporation of zinc compounds in paints also due to its relatively high toxicity. Phosphates are also questioned because of their role in the eutrophication of water courses. The aim of this investigation was to study the possible replacement of zinc phosphate by cerium modified minerals. Zeolites and halloysites were selected to be modified by cerium ions. The anticorrosive performance of these modified minerals was assessed by electrochemical techniques (corrosion potential and linear polarization measurements) coupled with scanning electron microscopy to study the morphology of the protective layer. The surface composition was also determined by EDX analysis. The modified silicate materials were incorporated in alkyd paints at different concentrations. The paints were brush applied onto SAE 1010 steel panels until the dry films thickness was 75 5 m. painted panels were subjected ti different tests to evaluate the anticorrosive performance of the formulated paints: salt spray chamber, electrochemical impedance and electrochemical noise measurements. Results showed that, at least, two thirds of the zinc phosphate content could be replaced by these silicate materials without impairing the anticorrosive properties of the coating. Results form EIS and ENM were also compared