| 摘要 |
PROBLEM TO BE SOLVED: To form a film having satisfactory and uniform appearance and excellent corrosion resistance properties without using chromium harmful to the environment and the human body when forming a protective film on the surface of steel, a galvanized steel, aluminum or the like. SOLUTION: In this chromium-free composition for metal surface treatment, a film formed by surface treatment to a metallic surface contains plural metallic elements, and, at least one above metallic element has plural valences.
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