| 摘要 |
PURPOSE: To provide a composition for surface treatment which is formed on the surface of a metal material such as iron, zinc, zinc-containing plating, aluminum, an aluminum alloy, magnesium, a magnesium alloy or the like and obtains improved corrosion resistance even in the state that it is uncoated or coated. CONSTITUTION: The composition for surface treatment comprises zinc, phosphoric acid and an aromatic nitro compound, wherein concentration of the zinc £Zn| (the unit is mol/L), concentration of the phosphoric acid £PO4| (the unit is mol/L) and concentration of the aromatic nitro compound £NO2| (the unit is mol/L) satisfy the relation of 100<={£Zn|/£PO4|}/£NO2|<=700. The treatment liquid for surface treatment comprises zinc, phosphoric acid and an aromatic nitro compound, wherein concentration of the zinc £Zn| (the unit is mol/L), concentration of the phosphoric acid £PO4| (the unit is mol/L) and concentration of the aromatic nitro compound £NO2| (the unit is mol/L) satisfy the relation of 100<={£Zn|/£PO4|}/£NO2|<=700.
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