THE EFFECT OF BENZOTRIAZOLE INCORPORTATED IN ZINC PHOSPHATE LAYER AS CORROSION INHIBITOR OF CARBON STEEL Everson do Prado Banczek* 1 , Paulo Rogério Pinto Rodrigues 2 and Isolda Costa 1 Av. Professor Lineu Prestes, 2242, São Paulo-SP, CEP: 05508-000, e-mail:edopradobanczek@yahoo.com.br 1 IPEN/CNEN-SP – CCTM-, São Paulo, Brazil. 2 UNICENTRO - Departamento de Química– Guarapuava, Brazil. ABSTRACT Phosphating and corrosion inhibitors are commonly used for corrosion prevention of metallic materials, mainly carbon steels. In this study, the effect of benzotriazole (BTAH) added to a Zinc phosphating (PZn) bath on the corrosion resistance of a carbon steel (1010) was investigated. Anodic polarization curves and electrochemical impedance spectroscopy (EIS) were used to evaluate the corrosion resistance of the phosphated steel with or without BTAH in 0.5 mol/L NaCl. The results showed better corrosion resistance for the steel phosphated with BTAH comparatively to that without BTAH. Keywords: Phosphating; inhibitors; benzotriazole; corrosion; carbon steel INTRODUÇÃO Phosphating is a conversion coating treatment largely used in many industries as a surface preparation for coating by paints and to increase corrosion resistance (1) . Phosphate layer on ferrous or non-ferrous metals (2-6) improve their surface properties by changes in the physico-chemical properties. The main applications of phosphating are for paints adhesion, to increase corrosion resistance, to oil impregnation and to promote electrical insulation (7,8) . Despite of their use for corrosion protection, phosphate layers by themselves do not produce considerable improvements in the metallic substrate corrosion resistance and need to be associated with other corrosion protection methods. 17º CBECIMat - Congresso Brasileiro de Engenharia e Ciência dos Materiais, 15 a 19 de Novembro de 2006, Foz do Iguaçu, PR, Brasil. 6093