Aluminum Basic Benzoate-Based Coatings: Evaluation of Anticorrosion Properties by Electrochemical Impedance Spectroscopy and Accelerated Tests

G. BLUSTEIN; R. ROMAGNOLI; J.A. JAÉN; A. DI SARLI; B. DEL AMO

CORROSION

NACE International

Año: 2007 vol. 63 p. 899 - 915

0010-9312

ABSTRACT Insoluble metallic benzoates can be prepared from the corresponding soluble salts. Soluble benzoates can be used as inhibitors in neutral solutions while insoluble ones can be employed as anticorrosive pigment for paints. This paper describes the experimental procedure to prepare aluminium basic benzoate to be employed in anticorrosive paints. The anticorrosive properties of aluminium basic benzoate were assessed by electrochemical techniques (corrosion potential and linear polarization measurements). The nature of the compounds forming the protective layer was determined by spectroscopic techniques (SEMEDXS, UV-visible diffuse reflectance, FTIR and Mössbauer). In a second stage, the anticorrosive properties of the pigment were evaluated by incorporating it in alkyd and epoxy anticorrosive paints which, in turn, were evaluated by accelerated (salt spray and humidity tests) and electrochemical measurements (electrochemical impedance spectroscopy). The morphology and the nature of the protective layer grown under the paint film in the salt spray chamber was assessed by scanning electron microscopy and UV-visible diffuse reflectance spectroscopy. Experimental results showed that basic aluminium benzoate was adequate to formulate solvent and water-borne epoxy anticorrosive paints with improved anticorrosive performance when it is employed in combination with zinc oxide. Zinc oxide counteracted the intrinsic acidity of basic aluminium benzoate. Solvent alkyd paints could also be prepared but with lower performance. Key words: anticorrosive coatings, aluminium basic benzoate, accelerated tests, electrochemical tests.: anticorrosive coatings, aluminium basic benzoate, accelerated tests, electrochemical tests.