WO2015111239A1 - Anodized member, and sealing method therefor - Google Patents

Abstract

[Problem] To provide: an anodized member exhibiting excellent alkali resistance and excellent water resistance; and a sealing method therefor. [Solution] An anodized member having an anodic oxide film formed thereon is characterized in that: the anodic oxide film is provided with a high-concentration layer which has a sealing metal content of at least 1.5 mmol/g, and which has a thickness from the surface of at least 0.15 µm; and the deposited amount of the sealing metal is at least 75 mg/m² with respect to the average film thickness of the anodic oxide film.

Description

Anodizing member and sealing method thereof

The present invention relates to an anodized member excellent in not only water resistance but also alkali resistance and a sealing treatment method thereof.

In the fields of aluminum, magnesium, titanium, and alloys thereof, anodization is performed for the purpose of rust prevention, designability, and the like.
On these metal surfaces, a non-porous thin barrier layer having a film thickness of several tens to several hundreds of nanometers and a porous layer having innumerable pores having a diameter of 100 to 600 mm are formed on the metal surface. Is done.
Since the anodic oxide film having a porous layer is inferior in corrosion resistance, various sealing treatments are applied.
Sealing treatment includes hydration sealing and metal salt sealing in which the sealing metal is deposited in the pores of the film.
Hydration pores often have insufficient alkali resistance, and metal salt pores often have insufficient water resistance to suppress surface whitening.
Therefore, the present applicant has previously proposed a technique for improving alkali resistance by pressurizing the sealing liquid (Patent Document 1).
For the purpose of improving water resistance, a technique has been proposed in which the thickness of a high concentration layer having a sealed metal content of 1.5 mmol / g or more is 0.15 μm or more (Patent Document 2).
In contrast, the present invention has been obtained as a result of studies aimed at improving alkali resistance and water resistance at a lower cost.

Japanese Patent No. 4884813 Japanese Unexamined Patent Publication No. 2012-144750

An object of the present invention is to provide an anodized member excellent in alkali resistance and water resistance and a sealing method thereof.

The anodized member according to the present invention is an anodized member on which an anodized film is formed. The anodized film has a high-concentration layer having a sealing metal content of 1.5 mmol / g or more from the surface. It has 15 μm or more, and the adhesion amount of the sealing metal with respect to the average film thickness of the anodized film is 75 mg / m ² or more.
Here, the sealing metal is preferably Ni or a combination of Ni and Co.
In the present invention, the average film thickness of the anodized film refers to the average thickness of the film of about 3 to 30 μm formed on the metal surface, and the amount of sealing metal attached per 1 m ^{2 of the} surface area of the film with the average thickness. The amount of sealing metal.

The anodized member thus treated has a whitening time of 10 minutes or more in an alkali resistance test with an alkaline aqueous solution at a liquid temperature of 25 ° C. and pH 13, and a whitening time in a water resistance test with 40 ° C. pure water. Has a characteristic of 240 hours or more.
In order to secure the above characteristics, the concentration of metal ions sealed with Ni ions or a combination ion of Ni and Co after forming a porous anodic oxide film on the metal surface is 4.0-10.0 g / l, fluorine ions It is preferable to immerse in a sealing liquid having a concentration of 1.0 to 3.0 g / l and then perform a water vapor sealing treatment.

In the method of pressurizing the sealing liquid of Patent Document 1, a pressurizing means is required.
Further, although the method of Patent Document 2 is excellent in water resistance, there is room for further improvement in alkali resistance only at the surface portion of the high concentration layer.
More specifically, the sealing metal ion concentration of the sealing liquid in Patent Document 2 is 30 to 60 mmol / l, which is 3.521 g / l of Ni ions in terms of g / l concentration. , 3.813 g / l of Co ions corresponds to 60 mmol / l.
Further, the fluorine ion concentration of the sealing liquid in Patent Document 2 is 70 to 120 mmol / l, which corresponds to 1.3 to 2.3 g / l.
With such a sealing liquid, it is possible to form a high-concentration layer of a sealing metal on the surface portion of the anodized film in an amount of 0.15 μm or more. However, when the thickness of the anodized film is 3 to 30 μm, It became clear that the adhesion amount of the sealing metal was less than the technique of Patent Document 1 in which the sealing liquid was pressurized.
For this reason, the technology of Patent Document 2 is sufficient for parts and members where alkali resistance is not at the technical level of Patent Document 1 and water resistance is more important than alkali resistance. In addition to the properties, there are cases where excellent alkali resistance is required.
Therefore, the inventors of the present invention have studied the improvement of the sealing liquid, and as a result, it has been known that the hardness of the anodic oxide film is lowered although the amount of impregnation of the sealing metal is increased by increasing the fluorine ion concentration. While there was a problem, the amount of adhesion by increasing the sealing metal ion concentration should be 75 mg / m ² or more while keeping the fluorine ion concentration in the range of 1.0 to 3.0 g / l. I was able to.

The method of water vapor treatment after anodic oxidation treatment or sealing liquid immersion in the present invention can incorporate the contents of Patent Document 2 and can similarly measure the high-concentration sealed metal layer on the surface by EDS analysis.

The metal material used for the anodized member according to the present invention may be any material that can form a porous film, and examples thereof include aluminum, magnesium, titanium, and alloys thereof.
Aluminum and its alloys are preferable.
Examples of the electrolytic solution for anodizing treatment include sulfuric acid aqueous solution, oxalic acid aqueous solution, and organic acid aqueous solution.
An aqueous solution having a sulfuric acid concentration of 100 to 300 g / l is preferable.
The electrolysis method may be DC, AC, a combination thereof, or a pulse waveform.
Furthermore, a coloring step such as electrolytic coloring or dyeing may be included after the anodization and before the sealing treatment.

The anodized member subjected to the sealing treatment of the anodized film according to the present invention was not visually whitened even when immersed in pure water at 40 ° C. for 240 hours, and was adjusted to pH 13, for example, at 25 ° C. Even when immersed in an aqueous sodium solution for 10 minutes, no whitening is observed visually.

The conditions of anodizing treatment and sealing liquid and the performance evaluation results are shown.

Hereinafter, the performance comparison by the difference in the sealing liquid of the anodized film will be described.
As a metal material, a JIS A6063S aluminum alloy extruded material was used for degreasing by a conventional method, and a phosphoric acid-based aqueous solution at 95 to 100 ° C. was used for chemical polishing, and the surface was mirror-finished.
By chemically polishing the surface, it is easy to visually evaluate the whitening change of the surface.
Next, electrolytic treatment was performed using an electrolytic solution having a sulfuric acid concentration of 200 g / l at a liquid temperature of 20 ° C. and a direct current density of 1.0 A / dm ² for 40 minutes to obtain an anodized film having an average film thickness of 12 μm.
Next, after rinsing with water, it was immersed in a sealing solution shown in the table of FIG. 1 for about 30 ° C. for 20 minutes, and after rinsing with water, hydration sealing was carried out for 20 minutes using 140 ° C. steam.
The temperature of the metal salt sealing treatment liquid is preferably in the range of 20 to 35 ° C., and the effect of hydration sealing is generally saturated when the sealing temperature is 140 ° C. or higher for 20 minutes or longer.
Specifically, it is contacted with steam at 140 to 160 ° C. for 20 to 30 minutes.

<Performance evaluation method>
(1) The thickness of the high concentration layer of the sealing metal in the surface portion was calculated for each element by analyzing the content mass ratio by SEM / EDS analysis.
For the calculation, atomic weights of Ni: 58.7 and Co: 58.9 were used.
(2) The amount of the sealing metal with respect to the average film thickness is determined by dissolving the film of the predetermined area, measuring the eluted metal ion concentration with an atomic absorption spectrophotometer, and calculating the average film from the obtained concentration. The metal ion adhesion amount per 1 m ^{2 with} respect to the thickness of 12 μm was calculated.
(3) Water resistance test After immersing in pure water at 40 ° C. for 240 hours, it was washed with water and dried.
(4) Alkali resistance test It was immersed in a 25 ° C. aqueous sodium hydroxide solution adjusted to pH 13 for 10 minutes, then washed with water and dried.

<Evaluation results>
In Example 1, as the sealing metal, Ni ion, 4.0 g / l sealing liquid was used, but the high concentration layer on the surface portion after the sealing treatment was Ni: 2.0 mmol / g, The thickness was 0.21 μm, and the amount of Ni adhered to the entire film (average film thickness) was 77.6 mg / m ² , exceeding the standard 75 mg / l. Therefore, both water resistance and alkali resistance cleared the targets. .
On the other hand, in Comparative Example 1, the sealing metal ion concentration of the sealing liquid is 1.7 g / l, which is lower than the standard 4.0 g / l, and the fluorine ion concentration is 0.7 g / l, which is the standard 1 Since it was lower than 0.0 g / l, the concentration of the sealing metal in the high-concentration layer on the surface portion was low, and the thickness was also 0.13 μm, which was thinner than the standard 0.15 μm.
Moreover, the adhesion amount of the whole film was as small as Ni: 42.0 mg / m ^2, and neither water resistance nor alkali resistance satisfied the standard.
In Comparative Example 2, although the standard of the high-concentration layer was clear, the amount of adhesion of the entire film was below the standard, so the water resistance was clear from the target, but the alkali resistance was insufficient.
In Examples 2 and 3, the Ni concentration was further increased, and all the quality targets were cleared.
Examples 4 to 6 are all mixed sealing liquids of Ni ions and Co ions. In this case, the concentration of the sealing metal ions is in the range of 4.0 g / l to 10.0 g / l, Since the fluorine ion concentration was in the range of 1.0 to 3.0 g / l, both were excellent in water resistance and alkali resistance.

The anodizing member according to the present invention is excellent in water resistance and alkali resistance, so it suppresses whitening due to rain water and has high corrosion resistance required, such as exterior parts of automobiles such as door frames, moldings, roof rails, etc. Can be widely deployed as automotive parts and parts.

Can be widely applied to anodized members that require high water resistance and alkali resistance.

Claims (5)

1. An anodized member formed with an anodized film,
   The anodized film has a high-concentration layer with a sealing metal content of 1.5 mmol / g or more from the surface of 0.15 μm or more,
   And the adhesion amount of the said sealing metal with respect to the average film thickness of an anodized film is 75 mg / m < ² > or more, The anodized member characterized by the above-mentioned.
2. The anodizing member according to claim 1, wherein the sealing metal is Ni or a combination of Ni and Co.
3. The whitening time is 10 minutes or more in an alkali resistance test with an aqueous alkali solution at a liquid temperature of 25 ° C. and pH 13,
   And the whitening time is 240 hours or more in the water resistance test by 40 degreeC pure water, The anodized member of Claim 1 or 2 characterized by the above-mentioned.
4. An automobile member using the anodized member according to any one of claims 1 to 3.
5. After forming a porous anodic oxide film on the metal surface, the concentration of sealed metal ions consisting of Ni ions or a combination ion of Ni and Co is 4.0 to 10.0 g / l, and the fluorine ion concentration is 1.0 to 3.0 g. A method for sealing an anodic oxide film, which comprises dipping in a / l sealing solution, followed by water vapor sealing.

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