A comparative study of anticorrosive paints containing polyphosphates

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

Recife, Brasil

Congreso; INTERCORR 2008, 28º CONGRESSO BRASILEIRO DE CORROSÃO – 2nd INTERNATIONAL CORROSION MEETING; 2008

Asociación Brasileña de Corrosión - ABRACO y NACE International

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 chambers) 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. Key words: corrosion, coatings, phosphate , tripolyphosphate, pyrophosphate, accelerated tests, electrochemical tests. corrosion, coatings, phosphate , tripolyphosphate, pyrophosphate, accelerated tests, electrochemical tests.