TW201542883A - Surface-treated aluminum material and zinc-supplemented aluminum alloy - Google Patents

Abstract

Provided are a surface-treated aluminum material having a porous anodic oxide film of uniformly porous type, in which the crystal grain pattern of an aluminum material comprising aluminum or an aluminum alloy is not visible subsequent to anodic oxidation treatment; and a novel zinc-supplemented aluminum alloy suited to manufacture of this surface-treated aluminum material. This surface-treated aluminum material has an aluminum alloy base material and an anodic oxide film formed on the surface thereof, and is characterized in that the aluminum alloy base material is formed of a zinc-supplemented aluminum alloy having an alloy composition in which the Zn component is 0.05-1 mass%, unavoidable impurities are 0.02 mass% or less, and the balance is aluminum.

Description

Surface treated aluminum and zinc-added aluminum alloy

The present invention relates to a surface-treated aluminum material having an anodic oxide film on the surface thereof and an aluminum alloy for adding zinc to be used for the surface-treated aluminum material, in particular, a surface-treated aluminum which is suppressed by the anodizing treatment to suppress the crystal grain pattern. material.

Aluminum made of aluminum or aluminum alloy is easily corroded by acid or alkali, so in order to impart corrosion resistance, wear resistance, aesthetics, functionality, etc., aluminum is generally widely used in an electrolyte solution. The material was energized as an anode, and anodizing treatment of an aluminum oxide (Al ₂ O ₃ ) film (anodized film) was formed on the surface thereof. Therefore, for example, in an anodizing treatment using an aqueous acid solution of oxalic acid, sulfuric acid, phosphoric acid or the like as an electrolyte, an anodized film called a positive film is formed by the anodizing treatment, but the positive film is called a barrier layer. The dense film on the inner side (aluminum side) is formed of a porous film called a porous layer having a plurality of holes formed on the outer side thereof, and in the initial stage of the anodizing treatment, a barrier layer is first formed corresponding to the treatment voltage, followed by the barrier layer. Most of the pores occur, and most of the pores grow to form a porous layer.

However, examples of the aluminum material other than the pure aluminum system (1000 series) include, for example, an Al-Cu system (2000 series), an Al-Mn system (3000 series), an Al-Si system (4000 series), and an Al-Mg system (for example). Aluminum alloys such as 5000 series) are industrially widely used in aluminum alloys in which other metals are added to improve strength or workability. However, various high-purity aluminum materials having high aluminum purity (Al purity) are subjected to various processes such as chemical dissolution treatment, electrolytic polishing treatment, and anodizing treatment after extrusion processing, cutting processing, and the like. Among them, there is an advantage that the influence of the second phase compound or the spacer which is a surface defect can be greatly reduced. Recently, for example, a member for a house such as a door handle or a fence, a steering member, a crank member, or the like, and a vehicle are used. Products for processing high-purity aluminum materials have been actively used for decorative components such as vehicle components, accessories, and timepieces such as door frames and interior trim panels, members for optical products such as mirrors and cameras, and rollers for printing. Development.

However, in the case of aluminum, there is generally a pattern (crystal grain pattern) resulting from crystal grains present in the material, and the crystal grain pattern is invisible to the naked eye before the anodizing treatment, but if anodizing is performed , is mainly due to the difference in crystal grain orientation. Further, in the aluminum material, if the Al purity is high, the crystal grain size tends to be larger, and it is more marked by the anodizing treatment. In particular, in the case of a high-purity aluminum material, the crystal grain size may be several hundreds μm or more, and may be several mm due to heat treatment.

Moreover, the problem that the crystal grain pattern is apparent can occur even when the surface of the aluminum material is planarized by polishing, electrolytic polishing, chemical polishing, cutting, etc., and is visually observed before the anodizing treatment. The crystal grain pattern recognized by the method is apparent by the anodizing treatment, and a uniform appearance cannot be obtained, and the appearance uniformity is considered depending on the use, and it is judged that the appearance is poor.

Therefore, as a method for solving the problem that the crystal grain pattern is apparent by the anodizing treatment, it is considered that the aluminum alloy is cast before the anodizing treatment, the cooling rate is adjusted, or the cold forging or the like is processed. Thereby, the size of the crystal grains present in the aluminum material is reduced to a size which is visually unrecognizable (about 100 μm), so that the apparent crystal grain pattern is inconspicuous. However, even if the crystal grain size in the aluminum material is less than 100 μm, if the crystal grains are aggregated to 100 μm or more, the problem of crystal grains during the anodizing treatment is also apparent.

Further, depending on the product, since the processing method of aluminum is limited, there is a limit to the reduction of the crystal grain size. In particular, when the aluminum material is a material having a high purity of Al or when heat treatment is required at the time of production, the crystal grain size is reduced to 100 μm or less. There are technical difficulties, and even if it is assumed that the size of the crystal grains can be reduced, when the crystal grains are aggregated in the aluminum material, since a large crystal grain like one is observed in appearance, it is difficult to obtain a uniform appearance.

However, it has been proposed so far that the crystal grain pattern which is apparent by the anodizing treatment is recognized as a design excellent appearance, and the aluminum material after the anodizing treatment hardens the crystal grain pattern (for example, reference patent document) 1) However, a development example of a material in which crystal grain patterns after anodizing treatment are difficult to be apparent is not observed.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 6-287773

Therefore, the present inventors first investigated in detail the reason why the crystal grain pattern was apparent by the anodizing treatment, and found that the aluminum material after the anodizing treatment was in the aluminum metal (Al)/barrier layer (Al ₂ O ₃ ). The shape of the interface is different for each crystal grain in each orientation. That is, in the anodizing treatment, a barrier layer is formed at the beginning of the formation of the film, and then the formed film starts to open, but if the orientation of the crystal grains is different, the orientation of the crystal grains is different, and the pores are different. The majority of the pores formed at the interface of the aluminum metal (Al)/barrier layer (Al ₂ O ₃ ) cause fine differences such as shape or unevenness, and the fine differences in the majority of the formed pores are also reflected in the subsequent Most of the pores grow on the porous layer formed. Further, the fine difference in the majority of the pores of the anodic oxide film thus formed is emphasized even when the difference is extremely small, and is emphasized when the light is irradiated onto the surface, and is apparent as a crystal grain pattern, and the aluminum material after the anodizing treatment cannot be obtained. The reason for the formation of a uniform appearance.

Therefore, based on the results of the review, the inventors of the present invention further reviewed the method of making the majority of the pores formed at the interface of the aluminum metal (Al)/barrier layer (Al ₂ O ₃ ) as uniform as possible irrespective of the crystal grain orientation. As a result, it was found that an aluminum alloy having a zinc content of 0.05 to 1% by mass, unavoidable impurities: 0.02% by mass or less, and the balance of aluminum alloy was used as the aluminum material in the initial stage of film formation. It is not easy to open the hole, and the hole can be uniformly opened due to the orientation of the crystal grain. In the subsequent anodizing treatment, a porous layer having a uniform shape hole can be formed, and the aluminum material after the anodizing treatment can be prevented as much as possible. The crystal grain pattern is conspicuous, and an anodic oxide film having few defects and uniformity can be formed, thus completing the present invention.

Accordingly, an object of the present invention is to provide a surface-treated aluminum material having a porous anodic oxide film having a uniform porous shape which is not recognized by an anodizing treatment.

Further, it is an object of the present invention to provide a novel zinc-added aluminum alloy which is suitable for producing a surface-treated aluminum material having a porous anodic oxide film having a uniform porous shape and which is not recognized by an anodizing treatment.

That is, the present invention is a surface-treated aluminum material having a surface-treated aluminum material having an aluminum alloy substrate and an anodized film formed on the surface thereof, characterized in that the aluminum alloy substrate is made of a zinc-added aluminum alloy. Formed, the zinc-added aluminum alloy has a Zn composition of 0.05 to 1% by mass, an unavoidable impurity: 0.02% by mass or less, and the balance: an alloy composition of aluminum.

Further, the present invention is an aluminum alloy to which zinc is added, which is an aluminum alloy obtained by adding Zn to high-purity aluminum, and is characterized in that the Zn component is 0.05 to 1% by mass, the unavoidable impurities are 0.02% by mass or less, and The rest is aluminum.

The surface-treated aluminum material of the present invention is obtained by subjecting an aluminum alloy substrate made of a zinc-added aluminum alloy to anodization, and the zinc-added aluminum alloy-based Zn component is 0.05% by mass or more and 1% by mass or less. It is preferably 0.25 mass% or more and 0.8 mass% or less, and the unavoidable impurities such as Si, Fe, Cu, Mn, Mg, Ti, Mg, and Ni other than the Zn component are 0.02% by mass or less, preferably 0.01% by mass or less. The rest is aluminum.

When the Zn component is less than 0.05% by mass, the zinc-added aluminum alloy is different in the occurrence of pores due to the crystal grain orientation, and it is difficult to exhibit an effect of suppressing the crystallization of the crystal grains. On the contrary, the Zn component exceeds When the amount is 1% by mass, the anodic oxide film is partially dissolved, and there is a flaw in the surface. In addition, when the unavoidable impurities other than the Zn component exceeds 0.02% by mass, the film which is caused by the partial dissolution of the film of the second phase particles or the portion where the film is not formed is generated as compared with the material having a high purity of Al, and cannot be formed. A wide range of consistent anodized films. In particular, it is desirable that the unavoidable impurities (for example, Fe, Si, Cu, Ni, and Ti) having a high Al potential have a partial dissolution of the film due to the anodizing treatment, and therefore it is preferably 0.01% by mass or less.

In the present invention, the surface of the aluminum alloy substrate may be planarized by grinding, polishing, electrolytic polishing, chemical polishing, or the like, and the shape thereof is not particularly limited, and for example, cast material or extrusion may be exemplified. Stretch materials for materials, plates, coils, etc. In particular, the aluminum alloy gold material subjected to the flattening treatment is advantageous in that the crystal grain pattern is easily formed by the anodizing treatment.

A method for producing a zinc-added aluminum alloy used in the present invention, There is no particular limitation on the alloy composition of the above-described zinc-added aluminum alloy, and the method for producing an aluminum alloy which has hitherto been generally used can be applied, and for example, gravity casting using a mold of a book type, a ship type, or the like can be used for the production of a cast material or the like. Gravity die casting, for example, a DC casting method for producing a cylindrical ring steel or a rectangular parallelepiped flat steel, for example, a continuous casting method for producing a plate-shaped ingot or the like, or as described later, in an aluminum alloy substrate. When the manufacturing step includes the aluminum alloy melting step, the necessary Zn is added to the high-purity aluminum in the melting step to prepare an aluminum alloy to which zinc having a specific alloy composition is added.

Further, the method for producing the aluminum alloy substrate used in the present invention may be, for example, a gravity casting method for producing the above-mentioned cast material, or an aluminum alloy having a shape such as a rod or a roll obtained by using the cylindrical steel obtained by the above-described DC casting method. The method of extruding a material, or using a rectangular steel having a rectangular parallelepiped shape obtained by the above-described DC casting method to obtain a hot or cold rolling method of a sheet, or using a plate-shaped ingot obtained by the above continuous casting method to obtain a cold rolling method of a sheet or a foil Wait.

In the present invention, an anodized film is formed by anodizing on the surface of an aluminum alloy substrate formed of the above-described zinc-added aluminum alloy. Further, the anodic oxidation treatment at this time is not particularly limited, but since the present invention is particularly effective for a porous anodic oxide film in which crystal granule patterns are easily apparent, it is preferred that the porous anode be formed. The polybasic acid aqueous solution of the oxide film is anodized as a treatment bath.

The polybasic acid used as the treatment bath in the anodizing treatment for forming the porous anodic oxide film is not particularly limited, and examples of the polybasic acid constituting the treatment bath include sulfuric acid, phosphoric acid, chromic acid, and the like. The organic acid such as mineral acid or oxalic acid, tartaric acid or malonic acid, and the polybasic acid concentration of the treatment bath (polybasic acid aqueous solution) using the polybasic acid may be the same as that used in the usual anodizing treatment, for example, in the case of sulfuric acid. It is 10% by weight or more and 20% by weight or less, preferably 14% by weight or more and 18% by weight or less.

Further, the treatment conditions for the anodizing treatment using the polybasic acid aqueous solution as the treatment bath are also not particularly limited as long as the anodizing treatment is carried out by a usual anodizing treatment, in particular, using a polybasic acid aqueous solution as a treatment bath to form a porous anodized film. The treatment may be carried out in the same manner. For example, when sulfuric acid is used as the treatment bath, the treatment bath temperature is 18 ° C, the treatment voltage is 10 to 15 V, and the film thickness is about 1 to 20 μm.

The surface-treated aluminum material of the present invention can be preferably used for forming an anodized film on the surface of an aluminum alloy substrate formed by adding zinc-added aluminum alloy having a specific alloy composition, and the crystal grain pattern is not noticeable, and the appearance uniformity is excellent. Industrially easy to manufacture, in particular, residential components, bicycle components, vehicular components, decorative components, components for optical products, components for building products, members for anodizing, etc., printing, etc. Use in rolls or the like.

Hereinafter, preferred embodiments of the present invention will be described more specifically based on examples and comparative examples.

[Example 1]

Adding 3.95 g of Zn with a purity of 99.9999% to 6.5 kg of high purity aluminum having a purity of 99.99%, melting in an experimental tank at 720 ° C, and casting it into a mold of a book mold preheated to 150 ° C by weight casting method. In an aluminum alloy substrate made of a zinc-added aluminum alloy of Example 1, in ×150w × 190l. The obtained aluminum alloy substrate was investigated for the composition of the alloy by glow discharge mass spectrometry (GD-MS method; apparatus: VG9000 type manufactured by VG ELEMENTAL Co., Ltd.), and was Zn: 0.05%, Si: 0.003%, Fe: 0.001%, Cu. : <0.001%, Mn: 0.001%, Mg: 0.003%, others: 0.002%, Al: the remainder. The results are shown in Table 1.

[Embodiment 2]

After adding 15.25 g of Zn having a purity of 99.9999% to 6.5 kg of high-purity aluminum having a purity of 99.99%, an aluminum alloy substrate made of a zinc-added aluminum alloy of Example 2 was obtained in the same manner as in Example 1, and the alloy was investigated. composition. The results are shown in Table 1.

[Example 3]

An aluminum alloy substrate made of a zinc-added aluminum alloy of Example 3 was obtained in the same manner as in Example 1 except that Zn 32.50 g of a purity of 99.9999% was added to 6.5 kg of high-purity aluminum having a purity of 99.99%, and the alloy was investigated. composition. The results are shown in Table 1.

[Example 4]

An aluminum alloy substrate made of a zinc-added aluminum alloy of Example 4 was obtained by adding 65.9 g of Zn having a purity of 99.9999% to 6.5 kg of high-purity aluminum having a purity of 99.99%, and the alloy was investigated after the aluminum alloy substrate of the zinc-added aluminum alloy of Example 4. composition. The results are shown in Table 1.

[Example 5]

An aluminum alloy substrate made of a zinc-added aluminum alloy of Example 5 was obtained in the same manner as in Example 1 by adding 65.00 g of Zn having a purity of 99.5% to 6.5 kg of high purity aluminum having a purity of 99.99%, and then investigating the alloy. composition. The results are shown in Table 1.

[Comparative Example 1]

Adding 0.65g of purity 99.9999% Zn to 6.5kg of high purity aluminum with a purity of 99.99%, melting it in an experimental tank at 720 ° C, and casting it into a mold of book-type mold preheated to 150 ° C by weight casting method. In an amount of ×150w × 190l, an aluminum alloy substrate made of a zinc-added aluminum alloy of Comparative Example 1 was obtained. The obtained aluminum alloy substrate was investigated for the composition of the alloy by glow discharge mass spectrometry (GD-MS method; apparatus: VG9000 type manufactured by VG ELEMENTAL Co., Ltd.), and was Zn: 0.01%, Si: 0.003%, Fe: 0.001%, Cu. : <0.001%, Mn: 0.001%, Mg: 0.003%, others: 0.002%, Al: the remainder. The results are shown in Table 1.

[Comparative Example 2]

Zn 130 g having a purity of 99.9999% was added to 6.5 kg of high-purity aluminum having a purity of 99.99%, and an aluminum alloy substrate made of a zinc-added aluminum alloy of Comparative Example 2 was obtained in the same manner as in Comparative Example 1, and the alloy composition was investigated. . The results are shown in Table 1.

[Comparative Example 3]

Into 6.5 kg of high-purity aluminum having a purity of 99.95%, 32.5 g of Zn having a purity of 99.9999% was added, and an aluminum alloy substrate made of a zinc-added aluminum alloy of Comparative Example 3 was obtained in the same manner as in Comparative Example 1, and the alloy was investigated. composition. The results are shown in Table 1.

[Comparative Examples 4 to 7]

For the aluminum alloy forming the aluminum alloy substrate, JIS A2024 alloy (Zn: 0.25, Si: 0.5, Fe: 0.5, Cu: 4, Mn: 0.35, Mg: 1.5, others: 0.1 was used in Comparative Example 4, and the rest: Al), JIS A3003 alloy (Zn: 0.1, Si: 0.6, Fe: 0.7, Cu: 0.1, Mn: 1.2, Mg: < 0.001, others: 0.1, the remainder: Al) was used in Comparative Example 5, Comparative Example 6 JIS A5052 alloy (Zn: 0.1, Si: 0.25, Fe: 0.4, Cu: 0.1, Mn: 0.1, Mg: 2.5, others: 0.006, the remainder: Al) was used, and JIS A6061 alloy was used in Comparative Example 7 ( Zn: 0.25, Si: 0.5, Fe: 0.7, Cu: 0.2, Mn: 0.15, Mg: 0.2, others: 0.45, and the balance: Al).

[Examples 6 to 26]

The aluminum alloy substrate of each of Examples 1 to 5 shown in Table 2 was cut out into an aluminum piece of 50 mm × 50 mm × 10 mm, and planarized by a buffing treatment to a surface roughness Rt < 200 nm to obtain a mirror gloss. Aluminum sheet (aluminum alloy substrate).

The thus obtained specular gloss aluminum sheet was anodized with the polybasic acid aqueous solution shown in Table 2 and the treatment conditions, and further washed with water and dried to obtain an anodized aluminum sheet of each of Examples 6 to 26 (test piece). : Surface treated aluminum).

[Evaluation of crystal grain patterns for surface observation]

The test piece obtained in each of Examples 6 to 26 was visually observed under a fluorescent lamp having an illuminance of 1,500 Lux or more and 2,500 Lux or less, and was observed as a ×, and an illuminance of 1,500 Lux or more and 2,500 Lux or less. When the crystal grain was not observed under the light, it was recorded as ○, and when the illuminance was 15,000 Lux or more and 20,000 Lux or less, the crystal grain was not observed under the illuminating light, and the surface was observed. The evaluation of the crystal grain pattern of each test piece was carried out.

The results are shown in Table 2.

[Evaluation of anodic oxide film by SEM observation]

The test pieces obtained in each of Examples 6 to 26 were observed by a scanning electron microscope (SEM) in the range of about 25 μm × 25 μm (corresponding to a field of view of about 5,000 times), and the evaluation of the anodized film was carried out by the evaluation criteria shown below. . ◎: The anodized film is uniform without defects, ○: observed in the field of view 1 to 10 anodic oxide defects of 5 μm or less in size, but no defects of 5 μm or more were observed. ×: 10 or more anodic oxide defects of 5 μm or less were observed in the field of view, or 1 or more sizes of 5 μm or more were not observed. Defective, or an anodic oxide film that does not form a consistent one.

The results are shown in Table 2.

[Overview]

The test pieces obtained in each of Examples 6 to 26 were subjected to comprehensive evaluation by the evaluation criteria shown below. ○: Any one of "surface observation evaluation" and "SEM observation evaluation" is ◎ or ○, and ×: "surface observation evaluation" and "SEM observation evaluation" are either △ or ×.

[Comparative Examples 8 to 14]

Using the aluminum alloy base materials of Comparative Examples 1 to 7 shown in Table 3, comparative aluminum sheets (aluminum alloy base materials) of Comparative Examples 8 to 14 were prepared in the same manner as in the above Examples 6 to 26, and then, The obtained comparative aluminum sheets of Comparative Examples 8 to 14 were anodized in a treatment bath of 2 wt%-oxalic acid (20 ° C) under the conditions of a voltage of 40 V and a quantity of electricity of 20 C/cm ² , washed with water and dried to obtain each. Comparative aluminum sheets of comparative examples 8 to 14 after anodizing treatment (comparative test piece: surface-treated aluminum).

With respect to the comparative test pieces obtained in each of Comparative Examples 8 to 14, the evaluation of the crystal grain pattern on the surface observation, the evaluation of the anodic oxide film by SEM observation, and the overall evaluation were carried out in the same manner as in the case of the above respective examples.

The results are shown in Table 3.

Claims (4)

A surface-treated aluminum material comprising a surface-treated aluminum material of an aluminum alloy substrate and an anodized film formed on the surface thereof, wherein the aluminum alloy substrate is formed by adding an aluminum alloy of zinc, and the zinc is added The aluminum alloy has a Zn composition: 0.05 to 1% by mass, an unavoidable impurity: 0.02% by mass or less, and the balance: an alloy of aluminum. The surface-treated aluminum material of claim 1, wherein the anodized film is formed by anodizing treatment with a polybasic acid aqueous solution as a treatment bath. The surface-treated aluminum material according to claim 1 or 2, wherein the aluminum alloy substrate is subjected to a planarization treatment by any one of a method selected from the group consisting of cutting, polishing, electrolytic polishing, and chemical polishing before the anodizing treatment. A zinc-added aluminum alloy obtained by adding Zn to high-purity aluminum is characterized in that the Zn component is 0.05 to 1% by mass, the unavoidable impurities are 0.02% by mass or less, and the balance is aluminum.