Zinc molybdenum phosphate as a corrosion inhibitor in paints

B. DEL AMO; G. BLUSTEIN; M. DEYÁ; R. ROMAGNOLI

Cartagena de Indias, Colombia

Congreso; LATINCORR 2002. 7th Ibero.American Congress of Corrosion and Protection, 4th NACE Latin-American Region Corrosion Congress; 2000

The objective of this work was to study the anticorrosive behaviour of micronized “zinc molybdenum phosphate” (zinc phosphate modified with zinc molybdate), with two different molybdenum content. The pigments were characterised in the laboratory by chemical analysis and their inhibitive properties evaluated employing electrochemical techniques. The morphology and the composition of the protective layer was also obtained by scanning electron microscopy (SEM) and EDAX analysis, respectively. The efficiency of the anticorrosive pigments was evaluated in solvent borne paints with 30 % of the pigment by volume and a PVC/CPVC ratio equal to 0.8. The behaviour of paints formulated with different binders such as epoxy and alkyd resins, has been assessed by accelerated (salt spray cabinet and humidity chamber) and  electrochemical tests. Epoxy paints showed the best anticorrosive performance. The inhibitive action of “zinc molybdenum phosphate” was confirmed. Good correlation was obtained between accelerated and electrochemical tests.