Abstract

ANNIES, V. et al. Study of Benzotriazole as Addictive for Carbon Steel Phosphating. Port. Electrochim. Acta [online]. 2010, vol.28, n.5, pp.279-298. ISSN 0872-1904.

The aim of this study is to evaluate the potential of benzotriazole (BTAH) for replacement of sodium nitrite (NaNO₂) in the zinc phosphate bath (PZn+NaNO₂) used for carbon steel (SAE 1010). Surface characterization of phosphated and unphosphated samples was carried out by Scanning Electron Microscopy, Energy Dispersive Spectroscopy, Optical Microscopy and X-ray diffraction. The corrosion resistance of the samples was evaluated by electrochemical techniques such as Open Circuit Potential, Electrochemical Impedance Spectroscopy and Anodic Potentiodynamic Polarization Curves, in a 0.5 mol L⁻¹ NaCl electrolyte at room temperature. The experimental results showed that not only benzotriazol (PZn+BTAH) presented better corrosion properties than sodium nitrite, but also the amount of the deposited phosphate increased approximately six times comparatively to the bath with sodium nitrite. The results demonstrated that benzotriazole (BTAH) is a potential candidate for replacement of sodium nitrite (NaNO₂) in zinc phosphate baths.

Keywords : phosphating; carbon steel; zinc phosphate; sodium nitrite; benzotriazole.

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