Performance of benzoate-based epoxy coatings under simulated marine corrosion conditions

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

Recife, Brasil

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

Asociación Brasileña de Corrosión - ABRACO y NACE International

Traditional anti-corrosive paints contain lead or hexavalent chromium compounds as active pigments, which contaminate the environment and, at the same time, represent a risk to human health. In this sense, it is believed that benzoates as anticorrosive pigments for paints could match environmental concerns with proved anticorrosive efficiency. The inhibitive properties of soluble benzoate compounds were known from many years ago and were studied employing sodium benzoate and benzoic acid, in different media, still those containing chloride. The employment of soluble compounds (benzoic acid, sodium benzoate, etc.) in anticorrosive paints is limited by the fact that their lixiviation by water penetrating the pores of the coatings would greatly increase coating permeability with the concomitant loss of the protective properties of the paint. However, it is possible to prepare anticorrosive pigments employing metallic benzoates with certain cations (e.g. zinc, aluminium, iron, etc.) whose compounds are widely used in paint technology. The objective of this investigation was to study the inhibitive properties of zinc basic benzoate-based paints in simulated marine corrosion condition (3% NaCl solution). The anticorrosive properties of lab-prepared pigment were investigated via electrochemical techniques in pigment suspensions. In a second stage, anticorrosive paints containing zinc basic benzoate were formulated and their performance was evaluated by accelerated (salt spray chamber) and electrochemical (EIS) tests. Experimental results show that zinc basic benzoate is adequate to formulate epoxy anticorrosive paints with improved anticorrosive performance in aggressive conditions, especially with the water-borne binder. Palavras-chave: corrosion, anticorrosive paints, benzoates, EIS. : corrosion, anticorrosive paints, benzoates, EIS.