JPS58117894A - Coloring method for aluminum or its alloy by immersion - Google Patents

Abstract

PURPOSE:To uniformly color an anodic oxide film golden yellow by immersing Al (alloy) having the formed anodic oxide film in an ammonium chromate soln. contg. an Ni salt or a Co salt. CONSTITUTION:An Ni salt such as nickel sulfate or a Co salt such as cobalt sulfate is dissolved in an ammonium chromate soln. having 1-30g/l concn. so as to adjust the concn. of the Ni or Co salt to 1-50g/l. Al (alloy) having a formed anodic oxide film is immersed in the resulting soln. and is uniformly colored golden yellow. Thus, the film which cannot be colored by immersion in a soln. of only an ammonium chromate, an Ni salt or a Co salt even at a high temp. can be uniformly colored golden yellow. The temp. of the ammonium chromate soln. contg. the Ni or Co salt is ordinary temp., and 40 deg.C is enough to obtain deep golden yellow.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for dip coloring an anodic oxide film of aluminum or its alloy.

Conventionally, aluminum casings or their alloys were used for sulfur shell electricity! A method for coloring one ounce of anodized skin golden yellow by anodizing using a conventional method such as Method 4 (2) A method of immersing it in a dye or pigment (2) In an aqueous solution containing an inorganic salt (3) There is a method of electrolytic treatment in an acidic solution containing a composition salt, but in methods (1) and 7), the dye is expensive and the sunlight fastness of the resulting color is extremely poor. Method (2) is difficult to manage the aqueous solution, and method (3) is difficult to manage the acidic bath solution, and has the disadvantage that it is difficult to obtain uniform coloring.

The present invention solves the above-mentioned drawbacks by immersing an aluminum strip or aluminum alloy with an anodic oxide film in an ammonium chromate solution containing a nickel salt or a cobalt salt.

Yang @! This is a method of coloring the oxide film to a uniform golden color.

There are two features of the present invention, one of which is td, (r'e rice).

Ammonium chromate solution alone, nickel salt tr1-separate solution.

With the cobalt salt alone solution, the anodic oxide film could not be colored even if I'=':>7 crystals were received.

The present invention is capable of coloring to a uniform golden color. Another is that in the method (2) described above, the temperature of the I-1 water bath solution is usually 60° or higher; however, in the present invention, the temperature of the ammonium chromate bath solution may be at room temperature; 40C is sufficient to obtain a deep golden coloration.

According to the invention, the concentration of an7ane chromate is 1 to 301/l.
If the needle is less than 17/, the color will be less colored,
Even if it exceeds 30 g/l, there is no effect of increasing the amount. For both nickel salt and cobalt salt, 1 to 50 f/l is commonly used, and 1y/l is common.
If it is less than 1, the coloring will be less yellowish, and if it exceeds 5oy7t, there will be no tow-increasing effect.

Next, two examples of the present invention will be described.

Example 1 Aluminum plate (AIlooP) with a total concentration of 10
Etch for 5 minutes in a 50C caustic soda solution, wash with water, and neutralize in nitric acid with a coagulation rate of 10% at room temperature.
i and washed with water at a current density of 1.3 A/d m2 in a sulfuric acid water bath with a tolerance of 15. Electrolysis time: 30 minutes, liquid temperature: 20 minutes
After anodizing under C electrolytic conditions, immersion treatment was performed in a 40C colored solution having the following composition.

Ammonium chromate 10y/L Nickel sulfate 309/ A uniform 71″f color was obtained on the anodized film in 300 seconds.

Example 2 Aluminum plate (Attoop) is used as a friend! Example 1 After performing etching treatment, neutralization treatment, and anodization treatment in the same manner as in Example 1, immersion treatment was performed in 40C Ir color having the following composition.

Chromic acid a/mon 10? /of Cobalt sulfate 30V/ Achieves uniform coloring on anodized film in 300 seconds Next, a comparative example will be presented.

Comparative Example 1 Aluminum plate (AIlooP) was subjected to etching treatment, neutralization treatment, and polar oxidation treatment in the same manner as in Example 1 (1
．． Immersion treatment was carried out in 1Oy/t of ammonium talomate at 60C.

There was no coloration on the anodic oxide film.

Comparative Example 2 After performing etching treatment, neutralization treatment, and anodization treatment on an aluminum plate (AIlooP) in the same manner as in the example,
Immersion treatment was carried out with 3 o2/l of 60C nickel sulfate.

Comparative Example 3 An aluminum plate (AIlooP) was subjected to etching treatment, medium etching treatment, and anodic oxidation treatment in the same manner as in the example, and then was coated with 60C cobalt sulfate 30? The immersion treatment was carried out at /l.

The anodized film was not colored at all.

Claims (1)

[Claims] Aluminum or its alloy with an anodic oxide film is immersed in an ammonium/chromate solution containing a nickel salt or cobalt salt to color the anodic acid film. Electrolytic coloring method for aluminum or its alloy.