JP3846940B2 - Colored aluminum alloy by anodic oxidation - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an aluminum alloy to be subjected to surface treatment, and particularly to an aluminum alloy for obtaining a color tone having excellent design properties by anodizing treatment.
[0002]
[Prior art]
Conventionally, many methods have been disclosed in which various components are added to aluminum to form an aluminum extruded shape, and then the color is developed by anodization.
For example, JP-A-1-172541 discloses a method for obtaining a milky white color, JP-A-2-254129 discloses a method for forming a gray natural color anodic oxide film, and JP-A-1-215946 and JP-A-2 No. -282495 discloses a method for obtaining a bluish gray color.
[0003]
[Problems to be solved by the present invention]
2. Description of the Related Art Conventionally, there are methods using an aluminum alloy component and methods using a special electrolytic solution such as an organic acid in an anodic oxidation treatment as a method for causing color development by anodizing treatment. In the case of using a special electrolytic solution, not only the surface treatment method is very limited, but also there is a problem that the chemical cost is generally high.
On the other hand, in the case of using an aluminum alloy component, there are many cases where the strength and productivity of the extruded aluminum shape are lowered.
Moreover, in the conventional 6063, it becomes a yellowish film | membrane by the influence of Si and Mg.
Accordingly, the present invention is to provide a silky-colored colored aluminum alloy that is widely used as an anodizing solution, uses an inexpensive aqueous sulfuric acid solution, has excellent extrudability and strength, and has no yellowness.
[0004]
[Means for Solving the Problems]
The most widely used aluminum alloy for extrusion is JIS6063 alloy at present, but it is a Mg ₂ Si precipitation hardening type alloy with Si and Mg. Usually, when anodized with sulfuric acid aqueous solution, the influence of Si and Mg is affected. Inevitably, it becomes a yellowish anodic oxide film.
Therefore, as a result of extensive research to obtain an aluminum alloy capable of forming a high-quality silky anodic oxide film while maintaining the extrudability and mechanical properties of JIS6063 alloy, the following findings were obtained. Is.
[0005]
In order to maintain the mechanical properties of the JIS6063 alloy, the Si and Mg components are Si: 0.2 to 0.6% by weight (hereinafter, unless otherwise indicated, weight%), Mg: 0.45 to 0.09 is required. Since only this component causes yellowing in the anodized film, addition of Mn and Cu was examined as a method for eliminating yellowing.
As a result, yellowishness disappears in the combination of Mn: 0.10 to 0.50, Cu: 0.10 to 0.30, and the delay effect during heat treatment of the aluminum extruded shape due to the addition of Mn is offset by Cu, The deterioration of mechanical properties could also be prevented.
However, the yellowish color disappeared, but the bluish color developed. Therefore, as a result of further studying the Fe component, bluishness was suppressed in the range of Fe: 0.15 to 0.35, and a silky tone without yellowness was obtained.
At this time, chemical polishing treatment was performed with an aqueous solution in which phosphoric acid and nitric acid were mixed, and then an anodic oxidation treatment was performed using an aqueous solution of sulfuric acid alone.
[0006]
【Example】
Example 1 (Reference Example)
Billet cast using an aluminum alloy consisting of Si: 0.45, Mg: 0.50, Mn: 0.20, Fe: 0.18, Cu: 0.15, the balance Al and unavoidable impurities, width 30 mm, Extruded into a plate with a plate thickness of 6 mm, pretreated by conventional methods such as degreasing using a material subjected to artificial aging treatment at 195 ° C. for 3 hours, and using a 15% aqueous solution of sulfuric acid to a liquid temperature of 20 ° C. Current density 100 A / m ²
, And anodized for 30 minutes. As a result, a silky-like appearance without yellow was obtained, and the yield strength (0.2%) was 200 MPa.
[0007]
Example 2
The aluminum alloy extruded profile described in Example 1 was degreased by a conventional method, and after chemical polishing for 60 seconds with an aqueous solution of phosphoric acid 80%, nitric acid 4%, and 98 ° C. The anodizing treatment described was performed.
As a result, as compared with Example 1, a slightly glossy, silky-like appearance without yellowness was obtained.
[0008]
Example 3
Billet cast using an aluminum alloy consisting of Si: 0.55, Mg: 0.70, Mn: 0.15, Fe: 0.30, Cu: 0.25, balance Al and inevitable impurities, width 30 mm, Extruded into a plate with a thickness of 6 mm, mechanically buffed and degreased using a material that was artificially aged for 3 hours at 195 ° C., 60 seconds in an aqueous solution of 75% phosphoric acid, 3% nitric acid, 98 ° C. After the chemical polishing treatment, anodization was similarly performed with an aqueous sulfuric acid solution for 30 minutes according to a conventional method.
As a result, a silky-like appearance without yellowing was obtained.
The yield strength (0.2%) of this material was 240 MPa.
[0009]
【The invention's effect】
According to the aluminum alloy having the composition according to the present invention, a silky tone without yellow can be economically obtained by a conventional anodizing treatment with a sulfuric acid aqueous solution.

Claims (1)

In weight%, Si: 0.2-0.6, Mg: 0.45-0.90, Mn: 0.10-0.50, Fe: 0.15-0.35, Cu: 0.10 0.30 and inevitable impurities 0.05, the balance being extruded aluminum alloy consisting of Al, after the chemical polishing treatment with a mixed aqueous solution of phosphoric acid and nitric acid, anodizing in an aqueous solution of alone sulfate An aluminum alloy extruded profile characterized by having a silky-like appearance without yellowness .