Coated Steel Sheet. Present Situation and Future Prospect. Relationship between Fine Structure of Coatings and their Corrosion Resistance for Zinc System Coated Steel Sheets.

Abstract

Zinc coated steel sheets have been widely used for automobiles, home electrical appliances, construction materials and so on, because of their high corrosion resistance and other excellent properties. The high corrosion resistance of the zinc coated steel sheets depends on the structures of both the surface coatings and the corrosion products formed under each environment. Characterization of the fine structures of the coatings by micro beam analysis clarifies the mechanism of the corrosion resistance and thus provides the concept for designing the coatings. Firstly, the environment of the used vehicles were estimated by the XRD analysis of the corrosion process and products of the zinc coatings. Secondly, the relationship between the fine structures and the corrosion resistance of the Zn system coatings are described through the characterization of the change of the coatings for the Zn-Ni electrodeposited alloy and electrodeposited Zn-SiO2 coatings during the corrosion process.