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AssigneeNippon Steel Corporation
InventorsKiyokazu Isizuka, Hidetoshi Shindou, Teruaki Yamada, Kimitaka Hayashi, Ikuo Kikuchi
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The present invention aims at provision of an organic composite galvanized steel sheet having its characteristics such as corrosion resistance and workability improved. Thus, the present invention provides an organic composite galvanized steel sheet that is formed by sequentially depositing on a surface of a steel sheet a galvanization layer, a zinc phosphate layer containing Mg, and an organic layer, and is characterized in that a value of Mg/P (weight ratio) in the zinc phosphate layer is 0.15 or larger and an amount of Mg contained in the zinc phosphate layer is 20 mg/m2 or more. Preferably, the zinc phosphate layer contains one or two or more of Ni, Mn, Co, Fe, Cu, Al, and Ca. In one preferred embodiment, the organic layer is formed as a composite layer containing an organic resin and one or two kinds or more of powder or colloid selected from SiO2, Al2O3, MgO, Fe2O3, Fe3O4, ZrO2, TiO2, and SnO2.
An organic composite galvanized steel sheet formed by sequentially depositing on at least one surface of a steel sheet a galvanization layer, a zinc phosphate layer in an amount of 0.3 g/m2 or more, and an organic layer in an amount of 0.3 to 2 g/m2, characterized in that the zinc phosphate layer contains Mg so that a value of Mg/P (weight ratio) in the zinc phosphate layer is 0.15 or larger and an amount of Mg contained in the zinc phosphate layer is 20 mg/m2 or more.
Dependencies are inferred from the claim text.