JP2005154858A - Aluminum surface treated material for forming - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an aluminum surface treated material for forming having satisfactory corrosion resistance, and to which surface treatment has been performed before forming, and forming can be satisfactory performed. <P>SOLUTION: The aluminum surface treated material is obtained by forming a nonporous anodized coating 2 having a porosity of ≤5% and a film thickness of 30 to 300 nm on the upper layer of an aluminum base material 1, and forming a lubricant layer 3 on the upper layer of the nonporous anodized coating 2. Desirably, the quantity of the lubricant is 0.01 to 10 g/m<SP>2</SP>, and a solid lubricant is used. By the nonporous anodized coating 2 having a porosity of ≤5%, the surface of the aluminum material 10 is provided with dense and hard properties, and the thickness of the lubricant layer 3 may be the minimum required one. The nonporous anodized coating performs protective function for the aluminum material, and prevents the galling and seizure between a die and the aluminum material. The damage to the nonporous anodized coating at the time of forming is reduced, and the characteristics of the coating can be maintained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an aluminum surface treatment material for forming that can be used as a material for processing a casing, a container, an electronic component or the like that requires good corrosion resistance.

2. Description of the Related Art Conventionally, it has been widely practiced to use an aluminum material as a plate material and form it into a processed product such as a housing, a container, or an electronic component. Further, since many of the processed products require corrosion resistance, in general, chromate treatment and coating are performed after processing. However, the surface treatment after processing needs to be performed for each product, which increases costs. Therefore, in order to reduce costs, a method of performing chromate treatment or alumite treatment (porous) on a coil of an aluminum material before processing is also employed.
By the way, since the surface of the aluminum material is relatively soft, there are cases where a predetermined shape cannot be formed due to seizure or galling in the mold during molding. In addition, there is a problem that the aluminum powder generated at that time adheres to the mold and adheres to the surface scratch or the molded product as dirt. Even when the film treatment is performed before processing, the film formed by this treatment is fragile, so it cannot be expected to suppress galling during processing. In addition, there is a problem that the film is damaged during processing and the corrosion resistance is lowered. In order to avoid these problems, a sufficient amount of processing oil is applied to the aluminum material by spraying or the like during the forming process.

However, excessive processing oil adheres to the press molding machine and mold, leading to contamination of the press mold. Furthermore, application of excessive processing oil increases the burden of a degreasing process for removing the processing oil after processing, and there are cases where the processing oil is not sufficiently removed by degreasing.
On the other hand, if the use of the processing oil is suppressed, there is a possibility that a galling or the like may occur due to, for example, an area where the processing oil is not sufficiently applied. In addition, the above-described chromate film and anodized film may be damaged even in a molding process using a sufficient processing oil, resulting in a problem that the product yield is poor.

  The present invention has been made against the background of the above circumstances, and can be subjected to surface treatment before molding processing, and can eliminate galling of aluminum materials and damage to the surface treatment film without requiring the use of excessive processing oil. It is an object of the present invention to provide an aluminum surface treatment material for forming that can be formed without raising.

  In order to solve the above problems, among the aluminum surface materials for forming according to the present invention, the invention according to claim 1 is characterized in that the porosity of the upper layer of the aluminum substrate is 5% or less and the film thickness is 30 to 300 nm. A porous anodized film is formed, and a lubricant layer is formed on the nonporous anodized film.

The invention for an aluminum surface treatment material for forming according to claim 2 is characterized in that, in the invention according to claim 1, the amount of the lubricant is 0.01 to 10 g / m ² .

  The invention of the aluminum surface treatment material for forming according to claim 3 is characterized in that, in the invention according to claim 1 or 2, the lubricant is a solid lubricant.

  That is, according to the present invention, the surface of the aluminum material has a dense and hard property because the nonporous anodic oxide film having a porosity of 5% or less is formed. For this reason, the lubricant layer formed on the surface of the aluminum material is sufficient, and it is not necessary to apply processing oil more than necessary as in the prior art. With this excellent lubricity, it is possible to cope with complex shapes and high molding speeds. Further, the nonporous anodic oxide film serves to protect the aluminum material by its own hard properties and the presence of the lubricant layer, suppresses galling and seizure between the aluminum material and the mold during processing, Contamination due to adhesion is also suppressed. Further, the nonporous anodic oxide film is hardly damaged during molding, and good characteristics (for example, corrosion resistance) of the film are maintained. The nonporous anodic oxide film may be formed on one side or both sides of the aluminum substrate, and according to this, the lubricant layer may be formed on one side or both sides. Good.

  In the nonporous anodic oxide film, it is necessary to make the film thickness 30 nm or more in order to obtain the above-described action, and the film thickness of 30 nm or more causes less film cracking due to processing, and also provides sufficient corrosion resistance. In particular, since it is a non-porous film, it has a stronger action of suppressing the entry of corrosive substances than a porous film such as general alumite. If it is less than 30 nm, the galling with the mold increases and the corrosion resistance becomes insufficient. On the other hand, if the film thickness exceeds 300 nm, cracks are likely to occur in the film during the molding process, and the corrosion resistance decreases. Therefore, the film thickness of the nonporous anodic oxide film needs to be in the range of 30 to 300 nm. For the same reason as described above, it is desirable that the lower limit is 80 nm and the upper limit is 200 nm.

  In addition, the nonporous anodic oxide film is not required to be completely nonporous, and may have a porosity of 5% or less. If this porosity exceeds 5%, the film becomes brittle, the workability is lowered and the corrosion resistance is insufficient. The porosity is more preferably 3% or less, and most preferably non-porous.

  In addition, as a method for measuring the porosity, the surface of the anodized film was observed at 10 arbitrary positions at 50,000 times (minimum viewing area of 2.0 nm × 2.0 nm) of the electron microscope, and the area ratio of the holes Is obtained as an average value. However, irregular places where the surface state is changed due to the presence of intermetallic compounds are excluded. As another measurement method, the cross-section of the film is cut, the same magnification and measurement location are observed with a transmission electron microscope, and the ratio can be obtained from the ratio of the hole on the outermost surface of the anodized film to the part that is not a hole. In these measurement methods, a recess having a depth of 3 nm or more and a size of a circle equivalent diameter of 3 nm or more is regarded as a hole. If the porosity is measured to be 5% or less by any of these methods, it can be said that the porosity condition of the present invention is satisfied.

In the lubricant layer, mineral oil, edible oil, polyoxyethylene-based, polyglycerin ester-based, etc. can be used as the lubricant, and polyoxyethylene-based, polyglycerin ester-based are most suitable.
In the lubricant layer, it is desirable to use a solid lubricant (including one that solidifies after application). After the solid lubricant is formed on the surface of the aluminum material, the coating amount does not change due to volatilization, and the lubricity can be stably maintained. Accordingly, any solid lubricant may be used as long as it is in a solid state at least at room temperature (preferably higher temperature).
Polyoxyethylene, indicating polyglycerol ester more specifically, polyoxyethylene alkyl ether _{[C 12 H 25 -O- (CH} 2 -CH 2 O) n-H], decaglycerol monolauryl ester _{RO- (CH 2 -CH (OH)} CH 2 O) n-R (R is a hydrogen atom or a fatty acid residue) is preferred. These lubricants are solid at room temperature, and do not volatilize and change the coating amount when applied to a coiled plate. Furthermore, if it is a solid lubricant, the automatic feeder for feeding the material to the mold and the line for transferring the processed molded body are less contaminated, and the dirt on the line can be prevented from reattaching to the processed product. More preferably, it is a polyglycerol ester type.

The amount of lubricant is not limited to a specific one in the present invention, but is preferably 0.01 to 10 g / m ² per surface area of the aluminum material. If it is less than 0.01 g / m ² , the lubrication performance is insufficient, and galling with the mold increases during the molding process. Further, even if it exceeds 10 g / m ² , the lubrication performance is saturated, the lubricant is peeled off and accumulated on the mold, and there arises a problem that it adheres to the surface of the processed product and increases dirt. Therefore, it can be said that 0.01 to 10 g / m ² is desirable as the amount of lubricant. For the same reason as described above, it is desirable that the lower limit of the lubricant amount is 0.1 g / m ² and the upper limit is 5 g / m ² .

As described above, according to the aluminum surface treatment material for molding of the present invention, a nonporous anodic oxide film having a porosity of 5% or less and a film thickness of 30 to 300 nm is formed on the upper layer of the aluminum substrate. Since the lubricant layer is formed on the nonporous anodic oxide film, the surface treatment can be performed before the molding process, and it is not necessary to perform the surface treatment for each product after the processing. The manufacturing cost can be reduced by greatly improving the manufacturing cost. In addition, without excessive processing oil being required for the molding process, the mold can be satisfactorily molded by preventing the occurrence of galling and the like, and the film is not damaged. In addition, since excessive processing oil is not required, contamination of automatic feeders and lines that send materials to the mold during molding can be avoided as much as possible, especially by adopting solid lubricant as a lubricant. It can be surely prevented.
The processed aluminum surface-treated material is free from surface scratches and dirt, and a good molded product can be obtained. In addition, the nonporous anodic oxide film is hardly damaged by molding, and the desired characteristics such as excellent corrosion resistance can be surely obtained.

Hereinafter, an embodiment of the present invention will be described. FIG. 1 is an enlarged cross-sectional view showing an aluminum surface treatment material 10 for forming which is an example of the present invention.
The aluminum base material 1 as a material of the aluminum material 10 is made of a pure aluminum plate or an aluminum alloy plate having an appropriate composition, and can be manufactured by melting, casting, rolling, etc. by a conventional method. It is not limited to the manufacturing process.
The aluminum substrate may be either pure aluminum or an aluminum alloy. The aluminum alloy can have an appropriate composition, and the composition is not particularly limited in the present invention. For example, JIS 1000 series pure aluminum and JIS 5000 series and 7000 series aluminum alloys can be used.

A nonporous anodized film 2 is formed on the upper layer of the aluminum substrate 1 by anodizing treatment. In forming the nonporous anodic oxide film 2, a pretreatment may be performed if desired. Examples of the pretreatment include degreasing and washing.
Subsequently, the nonporous film 2 is formed on the upper and lower layers of the aluminum base 1 by subjecting the aluminum base 1 to an anodic oxidation treatment in an electrolytic bath. As an electrolytic bath, boric acid, borate, phosphate, adipate, phthalate, benzoate, which are electrolytes that are difficult to dissolve the produced nonporous film 2 and that produce the nonporous film 2, are used. An aqueous electrolyte solution in which one or more selected from the group consisting of tartrate, citrate, silicate and the like is dissolved can be used. Of these electrolytes, boric acid, adipate, and phthalate are preferable in terms of the properties of the oxide film, cost, and the like. Examples of the electrolyte concentration in the aqueous electrolyte solution range from 2% by mass to the saturation concentration of the electrolyte. The bath temperature of the electrolytic bath is exemplified by a range of 20 ° C to 90 ° C.

In this electrolytic bath, the aluminum substrate 1 is electrolyzed by being connected to a power source so as to be an anode even if it is continuous or intermittent. An insoluble conductive material is used for the cathode. As the electrolytic current, a direct current is used. In direct current electrolysis, for example, electrolysis is performed at a direct current density of 1 to 30 A / dm ² and an electrolysis time of several seconds to 3 minutes.
The applied voltage is in the range of 21 to 215 V, preferably 57 to 142 V, because the thickness of the oxide film formed with respect to the voltage of 1 V is about 14 mm in the case of direct current. By such anodizing treatment, a nonporous film 2 having a uniform thickness is formed. The film thickness of the nonporous anode film 2 is 30 to 300 nm as described above.
The thus obtained nonporous anodic oxide film 2 has a porosity of 5% or less, and usually 2% or less. Moreover, the water content of the nonporous anodic oxide film 2 is 1 to 5% by mass, usually 1 to 3% by mass, which is a very low value.

In the aluminum substrate 1 on which the nonporous anodic oxide film 2 is formed as described above, the lubricant layer 3 is formed on the front and back surface layers. As a material for forming the lubricant layer 3, for example, a polyoxyethylene-based or polyglycerol ester-based solid lubricant is used. Lubricant amount, 0.01 to 10 g / ^{m 2} per aluminum material surface area, and more preferably to 0.1-5 g / ^{m 2.}
The lubricant layer can be formed by applying a lubricant to an aluminum material. For the application, means such as spraying, gravure printing, flow coating, roll coating, bar coating, and post-immersion roll drawing can be used. However, in the present invention, the coating method is not limited to a specific method. In addition, when applying a water-soluble solid lubricant, water or the like can be used as a solvent. If these solvents are volatile, they are easily volatilized and removed after application to an aluminum material.

  The aluminum surface treatment material 10 in which the nonporous anodized film 2 is formed on the aluminum substrate 1 and the lubricant layer 3 is formed thereon as described above is subjected to a molding process such as pressing. In the molding process, molding can be performed satisfactorily without causing special seizure and without galling or galling on the mold, and a molded product having a desired shape can be obtained.

  The resulting molded article can then be subjected to a lubricant layer removal treatment if desired. The molded article is formed with a hard and dense nonporous anodic oxide film 2, and desired characteristics such as good corrosion resistance are obtained.

Hereinafter, examples of the present invention will be described in comparison with comparative examples (production of materials).
A JIS3004 aluminum alloy plate having a thickness of 0.1 mm was prepared, degreased with a 10% NaOH solution at 50 ° C. for 10 seconds, washed with water for 10 seconds, neutralized with a 5% HNO ₃ solution at room temperature, and washed with water for 10 seconds. Next, the sample was connected to the plus side and anodized with the counter electrode as a carbon plate. As the electrolytic solution, an alkali metal salt, silicate, borate, tartrate, phosphate, or the like was used. Further, as shown in Table 1, the film thickness and the porosity were adjusted by adjusting the concentration of the electrolytic solution, electrolysis time, electrolysis temperature, and the like. The anodized sample was washed with water for 10 seconds and then dried at 80 ° C.

Moreover, the thing which chromated or anodized the aluminum alloy plate as described above was prepared as a comparative material. In the chromate treatment, phosphoric acid chromate treatment was carried out by a conventional method so that the chromium adhesion amount was 15 mg / m ² . In the alumite treatment, the material degreased in the same manner as above was immersed in 15% sulfuric acid, the sample was connected to the positive side, and the anodizing treatment was performed using the counter electrode as a carbon plate.

  A lubricant was applied to each sample material to form a lubricant layer. The types of lubricants were A: polyglycerin ester (decaglycerin monolaurate), B: polyoxyethylene (polyoxyethylene alkyl ether), C: mineral oil, and D: edible oil. The amount of lubricant is shown in Table 1.

  About each obtained test material, the porosity, lubricity, workability, and corrosion resistance were measured or evaluated. In addition, the measuring method and evaluation method in each test are as follows.

(Porosity)
The surface of the anodized film was observed at an arbitrary 10 points with an electron microscope of 50,000 times (minimum viewing area of 2.0 nm × 2.0 nm), and the area ratio of the holes was determined as an average value.

(Lubricity)
A sample (test material) was placed on a Bowden friction tester, and the friction coefficient was measured at a steel ball diameter of 7 mm, a load of 200 g, and a scanning speed of 4 mm / s.

(Processability)
The sample (test material) was blanked, drawn, wiped down, and curled and processed into a cup having a diameter of 200 mm and a depth of 50 mm. 1000 pieces were processed, and adhesion of dirt and cracks due to processing were observed. The case where there was no problem at all was evaluated as ◎, the case where only dirt was locally attached, ○, the case where several spots were observed as Δ, and the case where cracks occurred as x.

(Corrosion resistance)
A salt spray test was conducted for 10 days based on JIS regulations, and the corrosion state of the surface of the processed product was observed. No evaluation was evaluated as 腐 食, mild discoloration as ○, local corrosion of less than 5% area was evaluated as Δ, and corrosion exceeding 5% was evaluated as ×.

Table 1 shows the measurement results and evaluation results of each test. As shown in the table, in the material of the present invention, the porosity of the anodized film was 5% or less, and good results were obtained in any of lubricity, workability, and corrosion resistance. In addition, the thing using the polyoxyethylene type | system | group and the polyglycerin ester type | system | group was excellent in lubricity rather than the thing using mineral oil and edible oil as a lubricant. In addition, among the inventive materials, if the amount of the lubricant is outside the preferred range, there is some difficulty in workability.
On the other hand, in specimens having an anodized film with a porosity exceeding 5% or an inappropriate film thickness, or specimens subjected to chromate treatment or alumite treatment, any of lubricity, workability, and corrosion resistance It was clearly inferior.

It is an expanded sectional view showing the aluminum surface treatment material of one embodiment of the present invention.

Explanation of symbols

1 Aluminum base material 2 Nonporous anodized film 3 Lubricant layer

Claims (3)

  A nonporous anodic oxide film having a porosity of 5% or less and a film thickness of 30 to 300 nm is formed on the upper layer of the aluminum substrate, and a lubricant layer is formed on the upper layer of the nonporous anodic oxide film. An aluminum surface treatment material for molding processing characterized by the above. Claim 1 molding an aluminum surface treatment material, wherein the lubricant amount is 0.01 to 10 g / ^{m 2.}   The aluminum surface treatment material for forming according to claim 1 or 2, wherein the lubricant is a solid lubricant.

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