Drying effects on corrosion properties of Cr(VI)- and Cr(III)-treated electrogalvanized steel
conference paper
Drying effects on corrosion performance of Cr(VI)- and Cr(III)-treated electro-galvanized steel have been studied in NaCl solution using potentiodynamic measurements and electrochemical impedance spectroscopy (EIS), The Cr(VI) and the Cr(III) treated specimens were dried at three different temperatures: 60, 110 and 210°C. The surface layers were investigated using SEM, AES and XPS. The results show that the drying temperature not only affects the morphology of the surface layer, but also changes the chromium oxidation states in the layer. The corrosion protection given to the EG steel by Cr(VI) and Cr(III) pretreatments can be severely reduced if the pretreated surfaces are heated above 110°C. Both types of coating undergo some dehydration during heat treatments, which is undesirable for good corrosion protection, For Cr(VI) coatings, additional degradation mechanisms include widening of the cracks in the coating, and reduction of Cr(VI) to the Cr(III) oxidation state.
Topics
TNO Identifier
239674
ISSN
19385862
Source title
Corrosion Protective Coatings and Inhibitors - 208th Electrochemical Society Meeting, 16 October 2005 through 21 October 2005, Los Angeles, CA, Conference code: 69057
Collation
13 p.
Pages
165-176