| 摘要 |
PURPOSE: A method for forming colored coating film on the surface of aluminum is provided to form a colored (black) coating film on the surface of the metal aluminum product by anodizing the acidic solution coated metal aluminum product after dipping a metal aluminum product into an acidic solution containing iron complex compound. CONSTITUTION: The method for forming colored coating film on the surface of aluminum is characterized in that a colored (black) coating film is formed on the surface of the metal aluminum product by anodizing the aqueous sulfuric acid solution coated metal aluminum product using periodically changing current after dipping a metal aluminum product into an aqueous sulfuric acid solution containing iron complex compound, wherein the aqueous sulfuric acid solution is prepared by stirring the mixed solution at room temperature after adding about 5 g/L of aluminum sulfate of Al¬3+ to a 10 to 30% sulfuric acid solution, wherein cyan complex producing anionic iron complex ions in water, that is, any one complex selected from potassium hexacyanoferrate (III) (K3Fe¬3+(CN)6), potassium hexacyanoferrate (II) (K4Fe¬2+(CN)6) and oxalic acid complex (K3Fe¬3+(C2O4)3) contains Fe in the range of 0.1 to 50 g/L for the total aqueous complex compound solution, and wherein periodical changing time of current has the followings: {current: i1→i2→i1→i2→ i1>i2}, {period: (t1)60, (t2)10, (t1)60, (t2)10}, {i1: 4 A/dm¬2, i2: 1 A/dm¬2} and {t1: 60 sec, t2: 10 sec}.
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