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Monday, March 23, 2009: 3:20 PM
C205 (Georgia World Congress Center)
Ti/Zr conversion coatings are used as pretreatments for coil coated steel applications used for architectural claddings. However, little is known on the structure of the film formed, as well as their corrosion properties and adhesion properties when organic coatings are applied. In this work, the structure of the films formed using Ti/Zr pretreatments applied on hot-dip galvanized steel either by dipping or rolling has been studied.
Significant differences in the film structure were observed by X-ray photoelectron spectroscopy when the pretreatments were applied by dipping or rolling. In the later case, thicker films in the range of 27 nm (compared to 10 nm by dipping) were allowed to form at the hot-dip galvanized surface. In addition, the films were more homogeneous for the rolling procedure.
In terms of mechanisms, it has been demonstrated that the pretreatments act on the cathodic reaction through the formation of oxide (Ti and Zr) with higher band gaps thereby hindering the electron transfer of the cathodic reduction. The stability of the films was also studied upon exposure to humid air.
Significant differences in the film structure were observed by X-ray photoelectron spectroscopy when the pretreatments were applied by dipping or rolling. In the later case, thicker films in the range of 27 nm (compared to 10 nm by dipping) were allowed to form at the hot-dip galvanized surface. In addition, the films were more homogeneous for the rolling procedure.
In terms of mechanisms, it has been demonstrated that the pretreatments act on the cathodic reaction through the formation of oxide (Ti and Zr) with higher band gaps thereby hindering the electron transfer of the cathodic reduction. The stability of the films was also studied upon exposure to humid air.