A comparative study of anticorrosive paints cotaining polyphosphates

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

Recife, Brasil

Congreso; 28º Congresso Brasilero de Corrosao, 2nd International Corrosion Meeting; 2008

The objective of this work was to study the efficiency of the anticorrosive pigments obtained by substituting the phosphate anion in zinc phosphate by other polyphosphate anions such as tripolyphosphate and pyrophosphate. A procedure to prepare the pigments is outlined and their anticorrosive properties were evaluated following the electrochemical behaviour of a steel electrode in pigments suspensions. Two resins were chosen as film forming materials: an alkyd and an epoxy one. The performance of the resulting anticorrosive paints was assessed by accelerated (salt spray and humidity tests) and electrochemical tests (corrosion potential and ionic resistance). It was demonstrated that the substitution of the phosphate anion by tripolyphosphate or pyrophosphate anions, may give rise to effective anticorrosive pigments for paints. The essays performed with pigments suspensions suggested that zinc pyrophosphate has the best anticorrosive properties. The anticorrosive behaviour of the pigments in paints were found to depend on the resin employed to formulate the coatings.