The early corrosion behaviour of hot dip galvanised steel pre-treated with bis-1,2-(triethoxysilyl)ethane

The present work aims at correlating the evolution of the analytical composition of bis-1,2-(triethoxysilyl)ethane films formed on hot dip galvanised steel substrate during immersion in NaCl solution with the corrosion performance of the pre-treated substrates. The electrochemical tests were carried out by electrochemical impedance spectroscopy and the analytical characterisation was performed by X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and infrared spectroscopy (FT-IR). The electrochemical results show that the functional silane provides temporary corrosion protection for hot dip galvanised steel during immersion in NaCl-containing solutions. The analytical results show that the chemical composition of the silane film changes during immersion in the aggressive solution. During the first days of immersion these changes improve the corrosion resistance of the pre-treated substrate. (C) 2004 Elsevier B.V. All rights reserved.