Metallic coated steel having a siloxane film providing temporary corrosion protection and method therefor

摘要

A metallic coated steel such as a galvanized sheet is coated with a thin siloxane film having a preferred thickness of about 45 (Aangstroem) for providing temporary corrosion protection. The siloxane film is formed by rinsing the metallic coated sheet with an aqueous solution containing 0.5-2.0 vol. % silane and 0.1-1.0 vol. % crosslinking agent. The silane coating deposited on the rinsed sheet is cured at a temperature less than 200 degrees C. Preferred silane and crosslinking agents are (gamma)-aminopropyltriethoxy and (CH3O)3SiCH2CH2Si(OCH3)3 respectively. The siloxane film may be removed by rinsing the metallic coated steel sheet in an alkaline solution prior to coating the sheet with a phosphate conversion coating and a paint.