ANALYSIS OF THE CORROSION PRODUCTS ON GALVANIZED STEELS BY FTIR SPECTROSCOPY

FTIR reflectance spectroscopy has been used for the characterization o f products formed by an accelerated wet ageing test on industrial hot- dip galvanized steel. Several aluminium contents are selected. Various products have been detected in this study. The kind and amount vary w ith the substrate, the type of ageing test used, the relative humidity level and the temperature. The galvanized coatings studied show a mix ed zinc-aluminium compound, Zn6Al2(OH)(16)CO3. 4H(2)O. This phase is o bserved from the first exposure time on all coatings regardless of the amount of aluminium. Contrary to zinc, no basic aluminium compound ha s been detected. (C) 1998 Elsevier Science S.A. All rights reserved.