JP2003073853A - Surface treated aluminum material superior in corrosion resistance, and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface treated aluminum material superior in corrosion resistance and adhesion to a coated film. SOLUTION: The objective aluminum material comprises a metal substrate consisting of aluminum or an aluminum alloy, and a porous film of aluminum hydrous oxide with a thickness of 300-20,000 Å formed on the metal substrate. The above porous film traps or includes one or more kinds of Si or P, thereon or therein. An anodic oxide film may be formed between the porous film and the metal substrate.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to electric appliances, articles,
The aluminum material which is preferably used for decorative products, building materials, automobile parts, fin materials, etc., or aluminum alloy products, which has been subjected to a suitable base treatment and its manufacturing method. It is about technology that can be enhanced.

[0002]

2. Description of the Related Art Generally, when coating an aluminum plate or an aluminum alloy plate, a coating base treatment is performed in order to enhance the adhesion of the coating film. Examples of conventional coating base treatments include chemical film treatments such as chromate treatment and boehmite treatment, and porous anodizing treatment. The properties required for these coating base treatments are excellent coating film adhesion and corrosion resistance after coating. However, the conventional coating substrate treatment has the following problems. In the chromate treatment, the coating film adhesion and corrosion resistance show excellent performance, but chromium-containing drainage when applying the chromate film leads to environmental pollution, there is a drawback that the wastewater treatment costs high, Since chromium in the film is harmful to the human body for food-related applications, there is a demand for dechromization.

In the above boehmite treatment, when the thickness of the coating is reduced, the corrosion resistance deteriorates. Therefore, the thickness is usually 1 μm (10
It is common to form a film of 000 Å) or more, and because it has feather-like irregularities on the surface, an anchor effect is obtained, and it is said that the adhesion to the coating film tends to be high, but boehmite The water content of the coating is usually as high as 15 to 30% by weight, and there is a possibility that the adhesion of the coating may be significantly deteriorated due to evaporation of water from the boehmite coating, especially when baking coating is performed. Further, since the film is porous, the corrosive substance easily reaches the aluminum base material, and the corrosion resistance is not sufficient.

In the above-mentioned porous anodizing treatment, in the case of baking coating, there is a problem that the adhesion of the coating film is deteriorated due to evaporation of water and ions from the porous portion of the coating film as in the above-mentioned boehmite treatment. As a countermeasure against this, a measure such as not performing the sealing treatment which is usually applied to the porous anodic oxide film is taken, but in this case, the corrosion resistance may be insufficient. Further, in the porous anodizing treatment, a plurality of treatments such as degreasing, etching, desmutting, electrolysis and sealing are required in order to form an oxide film uniformly, which tends to increase the cost.

From these backgrounds, the present applicant has previously developed a non-porous anodic oxide film as disclosed in Japanese Patent Laid-Open No. 8-283990, and has developed aluminum having excellent coating film adhesion and corrosion resistance after coating. Provided the material. The aluminum material according to this patent has a thickness of 70 to 2000Å (0.00) on the surface of aluminum or aluminum alloy.
7 μm to 0.2 μm), the water content is 1 to 5% by weight, and the porosity is 5% or less. Further, this aluminum material is not the theory of generation of coating film adhesion that the conventional porous anodic oxide film obtains the coating film adhesion by exerting the anchor effect due to the unevenness of the surface portion due to the porosity, By eliminating the porous portion, the water and ions contained in the porous portion are eliminated, and a new phenomenon that the coating adhesion is not reduced due to volatilization of water and ionic components during coating drying. From the theory of coating film adhesion, it was to obtain excellent coating film adhesion.

[0006]

However, even in the case of this kind of non-porous anodic oxide coating, if a further strict quality is required for the coating adhesion, the coating adhesion may be insufficient. It was Therefore, the applicant of the present application has filed Japanese Patent Application Laid-Open No. 9-1840.
As disclosed in Japanese Patent Publication No. 93, etc., a thickness of 700 to 3000 is formed on the surface of aluminum or aluminum alloy.
We have developed a composite coating consisting of Å (0.07 μm-0.3 μm) boehmite coating and an anodized coating with a thickness of 70-2000 Å, and were able to further improve coating adhesion. However, in the aluminum material according to this patent, in order to improve the adhesion to the coating film, it is necessary to remove the water content in the boehmite film by a baking treatment to reduce the water content. Also,
When the above aluminum material was used without coating, the corrosion resistance was not sufficient in a severe environment in some cases.

Therefore, the inventors of the present application have conducted research on further improvement of coating adhesion and corrosion resistance of a boehmite film or an anodized film as an underlayer formed on the surface of an aluminum material on the basis of such a background. The present invention has been reached.

Based on the above background, an object of the present invention is to provide an aluminum material capable of further improving coating film adhesion and corrosion resistance, and a method for producing the same. Another object of the present invention is to provide an aluminum material having excellent corrosion resistance even when a coating film is not provided, and a method for producing the aluminum material.

[0009]

In order to solve the above-mentioned problems, the present invention provides a metal base material made of aluminum or an aluminum alloy and a thickness of 300Å formed on the metal base material.
A porous film of hydrated oxide of aluminum up to 20000Å is formed, and one or more kinds of Si and P are attached or contained on the surface or inside of the porous film. When one or more kinds of Si and P are attached or contained in the porous film, the corrosion resistance is improved and the coating film adhesion is also improved. Since the above Si and P have high bondability and affinity with the pigment generally contained in the coating film, the adhesion to the coating film is also good.

In order to solve the above problems, the present invention provides a metal base material made of aluminum or an aluminum alloy, a non-porous coating having a thickness of 50Å to 7,000Å formed on the metal base, and the non-porous material. Thickness of 300 Å formed on the film
And a porous film made of hydrated oxide of aluminum of 20000Å, wherein one or more kinds of Si and P are attached or contained in the film. If at least one of Si and P is attached or contained in the porous film,
Corrosion resistance is improved and coating film adhesion is also improved. In addition, when the non-porous film is formed on the lower side of the porous film, it is possible to prevent the corrosive substance from entering the metal base material side, and an aluminum material having extremely excellent corrosion resistance can be obtained. Since the above Si and P have high bondability and affinity with the pigment generally contained in the coating film, the adhesion to the coating film also becomes good.

In the present invention, it is preferable that at least one of Si and P is contained in the coating in the range of 20 ppm or more and 100000 ppm or less. Within this range, good coating adhesion can be achieved while maintaining good corrosion resistance. One or more of Si and P is 20
If it is less than ppm, it becomes difficult to obtain the effect of improving the corrosion resistance, and conversely, if it exceeds 100,000 ppm, the effect of improving the corrosion resistance becomes small, and the adhesiveness of the coating film tends to decrease. In the present invention, it is preferable that the porous film made of a hydrated oxide of aluminum is a boehmite film and the non-porous film is an anodized film. The boehmite film can be expressed as a hydrated oxide film having a boehmite structure (AlOOH).
When the porous film is a boehmite film, Si and P are adhered or impregnated, so that the effect of improving the corrosion resistance is surely exhibited. In the present invention, the non-porous coating is preferably a non-porous anodic oxide coating having a porosity of 30% or less. If a non-porous anodic oxide film is formed on the inside of the boehmite film, even if the corrosive substance passes through the porous film and enters the non-porous anodic oxide film side, the metal group of the corrosive substance The non-porous anodic oxide film prevents entry into the material side.

The manufacturing method of the present invention comprises forming a porous film of hydrated oxide on a metal substrate made of aluminum or an aluminum alloy, and then contacting or applying an aqueous solution of silicate or phosphate to the porous film. Then, the porous film is adhered or impregnated with Si or P in the aqueous solution. The manufacturing method of the present invention comprises forming a porous film of a hydrated oxide on a metal substrate made of aluminum or an aluminum alloy, and then performing anodizing treatment to form a non-porous oxide film, and a silicate on the film. Alternatively, it is characterized in that an aqueous solution of a phosphate is brought into contact with or applied to adhere or impregnate Si or P in the aqueous solution to the film. Even in the structure having a porous film or the structure having a non-porous film on the lower layer side in addition to the porous film, the S in the aqueous solution is added to the film.
By adhering or permeating i or P, corrosion resistance is improved and coating film adhesion is improved.

In the production method of the present invention, after forming a porous film of a hydrated oxide on a metal base material made of aluminum or an aluminum alloy, anodizing treatment is performed in an aqueous silicate solution or an aqueous phosphate solution. Form a porous oxide film,
At the same time, the film is coated with Si or P in the anodized aqueous solution.
Is adhered or impregnated. Further, the substrate with a porous film formed a non-porous anodic oxide film with a treatment liquid other than silicate or phosphate, anodized in an aqueous silicate solution or phosphate solution, S on the film
i or P can be attached or impregnated. If it is an anodic oxide film formed with an aqueous solution of silicate or an aqueous solution of phosphate, Si or P which is an electrolyte solution component during anodizing treatment
Has excellent corrosion resistance because it is electrically efficiently attached or impregnated in the film. Since Si and P have high bondability with the pigment generally contained in the coating film, the adhesion to the coating film can be improved.

In the present invention, an aqueous solution of silicate or phosphate can be applied to the above-mentioned base material having a coating to deposit the silicic acid component or the phosphoric acid component on the surface portion of the coating.
In the present invention, the porous film may be formed by boehmite treatment.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. FIG. 1 shows a first embodiment of an aluminum material according to the present invention. An aluminum material A in this embodiment is a plate-shaped metal base material 1 made of aluminum or an aluminum alloy and the entire metal base material 1. It is composed of a porous film 2 made of a hydrated oxide of aluminum having a thickness of 300Å to 20000Å formed on the outer surface. Although the porous film 2 of this embodiment is formed on the entire outer surface of the metal substrate 1 in FIG. 1, if the porous film 2 is formed on a surface required for corrosion resistance and coating adhesion. Since it is good, for example, it may be formed only on the front surface or the back surface of the metal substrate 1.

The base material 1 is made of aluminum or an aluminum alloy, and is made of pure aluminum such as JIS1000 series, Al--Cu series such as JIS2000 series, or Al--C.
u-Mg type, JIS3000 type Al-Mn type, JIS4
000 series Al-Si series, JIS5000 series etc. Al-M
g-based, JIS-6000 based Al-Mg-Si based, JIS
7000 series Al-Zn-Mg series, Al-Zn-Mg-C
Any of Al-Fe-Mn-based materials such as u-based material and JIS8000-based material may be used. Further, molding alloys, structural alloys, electrical alloys, AC1A, AC2 of these systems
It may be used in any form of cast alloy such as A, AC3A, AC4B.

The JIS1000 series pure aluminum series, the JIS2000 series, and the JIS3000 series are used in various parts, for example, so that the present invention can be applied to these applications. JIS
Since 4000 series products are used, for example, in building panels, the present invention can be applied to these applications. Since JIS 5000 series products are widely used in, for example, interior / exterior plates, decorative parts, name plates, etc., the present invention can be applied to these applications.
Since JIS 6000 series products are used in, for example, construction and ornaments, the present invention can be applied to these applications. Since JIS 7000 series is used for fin materials for heat exchangers, for example, the present invention can be applied to these applications.

In the present embodiment, the porous film 2 made of a hydrated oxide of aluminum formed on the metal substrate 1 is a so-called boehmite film in which at least one of Si and P is attached or impregnated. A coating is used. The above boehmite film is obtained by utilizing the fact that aluminum reacts with high-temperature water to form a quasi-boehmite hydrated oxide film. Therefore, the boehmite film itself is widely used for industrial purposes.

The method for forming this boehmite film will be described below. When a metal base material of aluminum or aluminum alloy processed into an appropriate shape of an alloy system suitable for the above-mentioned application is prepared, the metal base material is subjected to pretreatment. This pretreatment may be any treatment as long as it can remove the oil and fat components adhering to the surface of the metal base material and remove the heterogeneous oxide film and the like on the surface of the metal base material. For example, after performing degreasing treatment with a weak alkaline degreasing solution, after performing alkali etching with an aqueous solution of sodium hydroxide, a method of performing desmutting treatment with an aqueous solution of nitric acid, a method of performing acid cleaning after the degreasing treatment, etc. are appropriately selected. Used. Then,
A boehmite film is formed on the surface of the base material by subjecting the pretreated base material to a boehmite treatment in a construction bath water. Although high-temperature water can be used as the bath water, it is particularly preferable to use ion-exchanged water having an electric conductivity of 0.1 μS or less to prevent blackening of the substrate surface and to easily form a boehmite film. It is preferable in terms.

The temperature of the bath water is 90 ° C to the boiling point (100
C) range is desirable. The boehmite treatment in the present invention is
It may be appropriately adjusted according to the required thickness of the porous film, and the thickness is in the range of 300Å to 20000Å. Therefore, when the thickness of the porous film is thin, about 10 seconds to 5 minutes is sufficient, When the film thickness is large, the treatment is performed for more than 5 minutes and for about 120 minutes. To the construction bath water, it is preferable to use an alkaline additive such as ammonia, amine, alcohol amine, amide, triethanol amine, etc. in that the production rate of the boehmite film becomes faster, and in that case, the boehmite film In order to prevent the film thickness from becoming too thick, the boehmite treatment time is preferably as short as possible.

By such a boehmite treatment, a porous film (boehmite film) 2 of hydrated oxide having feather-like irregularities is formed on the surface of a metal base material of aluminum or aluminum alloy. The thickness of this boehmite coating is 300 to 20000Å, preferably 500 to 120.
It is about 00Å. If the boehmite film thickness is less than 300Å, good corrosion resistance cannot be obtained, and if the boehmite film thickness exceeds 20000Å, cracks are likely to occur in the film at the stage of winding into a coil, and the corrosion resistance tends to decrease. The boehmite film has a boehmite structure (AlOOH).
It can also be expressed as a hydrated oxide film having.

After the boehmite film is formed, at least one of silicate and phosphate is directly applied to the boehmite film, or the boehmite film surface is treated by energizing in an aqueous solution of silicate and phosphate. Alternatively, a treatment is performed in which at least one of silicate and phosphate is attached or contained therein. In order to deposit or include the silicate and the phosphate in the boehmite film by an electric current treatment, an aqueous solution of the silicate or the phosphate is prepared, and the metal substrate 1 with the boehmite film is immersed in the aqueous solution to form the positive electrode. It is preferable to apply electricity to the surface layer portion of the boehmite film by electrically conducting the aqueous solution with the aqueous solution as the negative electrode side.

The form in which at least one kind of silicate and phosphate is applied to the surface of the boehmite film and the Si and P are physically adhered to the boehmite film is the silicate on the feather-like porous portion of the boehmite film surface. It can be presumed that one or both of the phosphates are adsorbed. The state in which at least one of Si and P is impregnated inside the boehmite film means that either or both of silicate and phosphate are impregnated and bonded to the feather-like porous portion of the boehmite film in the form of ions. It can be presumed that the state is exhibited. If it is a silicate, it is presumed that it is bonded as an anodized film component in the form of a silicate ion represented by the formula SiO ₂ ²⁻ , and if it is a phosphate, it is the phosphate ion represented by PO ₄ ^3−. it can. The aluminum material A produced as described above has Si in the porous film (boehmite film) or on its surface.
Since it contains at least one kind of P, it has an effect of excellent corrosion resistance.

If necessary, the surface of the aluminum material on which the porous film 2 is formed is coated.
There is no particular limitation on the paint used for coating here, but the effect is most effectively obtained when a baking type is used. As such paints, thermoplastic acrylic resin-based paints, thermosetting acrylic resin-based paints, epoxy resin-based paints, polyurethane resin-based paints, polyester resin-based paints, polyamide resin-based paints and the like are used. The coating method is not particularly limited, but spray coating, roll coater method, gravure roll method, electrostatic coating method,
A cationic electrodeposition coating method or the like is used. In addition, a multi-layer coating such as an undercoat, an intermediate coat, and a top coat can be applied if necessary. In this way, a coated aluminum material is obtained. Further, in the case where the coating film is formed, Si and P have a binding property with the pigment contained in the coating film when the coating film is coated on the porous coating film 2, so that it is applied when the coating film is coated. Adhesion with the film is also good.

In order to contain Si and P in the porous film 2 as described above, in addition to the above electrolytic treatment, an aqueous solution containing Si or P is applied by a coating device such as a roll coater,
It can also be performed by drying at a temperature of about 0 ° C.
In this case, Si or P does not penetrate deep into the porous film 2, but the effect of the present invention can be obtained by allowing Si or P to exist on the surface of the porous film 2. Therefore, the porous film 2 may be electrolyzed to contain at least one of Si and P, and then an aqueous solution containing Si or P may be further applied with a coating device such as a roll coater, or vice versa. You may electrolyze from.

[Second Embodiment] Next, FIG. 2 shows a second embodiment of the aluminum material according to the present invention. The aluminum material B of this embodiment is used in the previous embodiment. From a metal base material 1 equivalent to the conventional one, a non-porous anodic oxide film 3 formed on the entire outer surface thereof, and a hydrated oxide porous film 5 formed on the anodic oxide film 3. It is configured. Although the anodic oxide coating 3 and the porous coating 5 of this embodiment are formed on the entire outer surface of the metal substrate 1 in FIG. 2, the anodic oxide coating 3 and the porous coating 5 have corrosion resistance and coating adhesion. Since it may be formed on a necessary surface above, it may be formed on only the front surface or the back surface of the metal substrate 1.

In this embodiment, the porous film 5 has at least one of Si and P adhered thereto, or contains these, as in the structure of the previous embodiment. In this form, the non-porous anodic oxide coating 3 has a porosity of 30%, unlike the conventional general porous anodic oxide coating.
Below, preferably as low as 5% or less, preferably with a water content of 1
.About.5% by weight, preferably 0.1 to 7% by weight of anion, non-porous or microporous.

In order to manufacture the aluminum material B having the non-porous anodic oxide coating 3 and the porous coating 5 having the above-mentioned structure, it is equivalent to the porous coating (boehmite coating) 2 formed in the previous embodiment. Porous film (boehmite film)
5 is first formed. The method of forming this porous film 5 may be the same as the method described in the previous embodiment. After the porous film 5 is formed on the metal substrate 1, the metal substrate 1 and the porous film 5 are then subjected to anodic oxidation treatment in which the metal substrate 1 is electrolyzed in an electrolytic bath. The anodic oxide film 3 can be formed on the boundary portion. The electrolytic bath is an electrolyte that is difficult to dissolve the non-porous anodic oxide film to be formed and is capable of forming a non-porous anodic oxide film, and S
As an electrolytic bath to which i and P can be added, a single electrolytic bath of sodium silicate or ammonium phosphate can be exemplified. The electrolyte concentration in the aqueous electrolyte solution is selected from the range of 2% by weight to the saturation concentration of the electrolyte. Bath temperature of electrolysis bath is 2
It is in the range of 0 ° C to 90 ° C.

In this electrolytic bath, the aluminum or aluminum alloy material is electrolyzed by being connected to a power source so as to become an anode even if it is continuous or intermittent. An insoluble conductive material is used for the cathode. A direct current is used as the electrolysis current, and in the direct current electrolysis, electrolysis is performed with a direct current density of about 1 to 30 A / dm ² and an electrolysis time of about several seconds to about 3 minutes.

The applied voltage is about 5 to 500 V, and preferably about 30 to 300 V, since the thickness of the oxide film formed is about 14 Å for a voltage of 1 V under direct current.
It is preferably in the range of V. From the viewpoint of a power supply device, it is preferably 200 V or less, and excellent coating adhesion and corrosion resistance after coating can be obtained even with such low voltage electrolysis. By such anodizing treatment, the non-porous anodized film 3 having a uniform thickness is formed as an underlayer of the porous film (boehmite film) 5. The thickness of the non-porous anodic oxide coating 3 is preferably 50 to 7,000 Å, more preferably about 400 to 4,000 Å. Film thickness is 50Å
If it is less than the above range, the thickness is too thin and it is difficult to obtain a further effect of improving the corrosion resistance. On the other hand, as the upper limit of the film thickness,
It is possible up to 7,000 Å, but even if it exceeds 4000 Å, the effect cannot be expected to increase anymore, and it becomes economically disadvantageous because the electrolysis time increases and the cost of electrolytic equipment increases, and the formability decreases. However, it is preferable that the thickness is 4000 Å or less, since the coating film tends to crack.

The anodic oxide coating 3 thus obtained is non-porous and its porosity is about 30% or less at the maximum.
It is preferably 5% or less, and usually about 2% or less. The water content of the anodic oxide coating is about 1 to 5% by weight, usually about 1 to 3% by weight, which is a very low value. Further, the anion content of the oxide film is about 0.1 to 7% by weight, usually about 1 to 5% by weight, which is a low value. On the other hand, the porous anodic oxide film obtained by a normal sulfuric acid bath or oxalic acid bath has a very high porosity of 30 to 70%, the water content is about 15% by weight after the sealing treatment, and the anion content is included. Quantity is 1
It is about 2 to 15% by weight. However, even in a sulfuric acid or oxalic acid bath, porosity of 30% or less can be used by stopping the electrolysis between the non-porous state and the porous state before being made porous.

Therefore, the anodic oxide film of the present invention has excellent corrosion resistance by suppressing the penetration of corrosive substances. In addition, the water and anions that volatilize from the film become remarkably fine, and the peeling of the film due to the release of water and anions during baking coating becomes small. Further, in the formation of the non-porous anodic oxide coating 3 in the present invention, the bath temperature of the electrolytic bath is wide, ranging from 20 ° C. to 90 ° C., so that bath management becomes easy. Furthermore, since the electrolyte having low oxide film solubility is used, the film is less likely to be dissolved during electrolysis and the current efficiency is improved. The above anodic oxidation treatment can be performed on unprocessed aluminum or aluminum alloy such as a coil, or can be performed on the aluminum or aluminum alloy after being subjected to processing such as pressing.

The aluminum material B manufactured as described above has a porous film (boehmite film) 5 containing Si and P.
Since it has both the non-porous anodic oxide film 3 and the porous film 5 of the previous embodiment, the aluminum material A
It has the feature that it is superior in terms of corrosion resistance. That is, since the anodic oxide coating 3 itself containing Si and P exhibits corrosion resistance in addition to the porous coating 5, more excellent corrosion resistance can be obtained.

If necessary, a resin coating film is further formed on the aluminum material B provided with these coating films. For this coating film, a resin coating film such as an acrylic resin film is selected. As the coating film here, one containing a pigment is used for displaying products, etc., but since the pigment contained in the above coating has excellent affinity with Si and P, Adhesion is also good.

[0035]

[Example] JIS standard pure aluminum alloy (JIS1
050) and a plurality of plate-shaped metal base materials made of aluminum and having a thickness of 0.3 mm were prepared. Alkali degreasing of these metal base materials (3% of Nippon Paint Surf Cleaner 330)
The solution was immersed in 60 ° C. for 30 seconds), washed with water at room temperature for 10 seconds, neutralized with 10% nitric acid for 30 seconds, and after the treatment, washed with water at room temperature for 10 seconds. Next, the pH of these metal substrates is 98 ° C.
It was immersed in ion-exchanged water adjusted to 9 and subjected to boehmite treatment. The thickness of the boehmite film was adjusted by appropriately adjusting the immersion time during the boehmite treatment.

A part of the plurality of boehmite-treated metal substrates was washed with ion-exchanged water for 10 seconds, the sample was connected to an anode, immersed in a 10% aqueous solution of boric acid, and the negative electrode was immersed in the aqueous solution. Electrolytic treatment was performed for 5 minutes at a current density of 1.0 A / dm ^{2 at} an aqueous solution temperature of 60 ° C. to form non-porous anodic oxide coatings of various thicknesses shown in Table 1 below. The thickness of this non-porous anodic oxide film was adjusted by the electrolysis time. After the electrolytic treatment, each sample was washed with water for 10 seconds and dried at 120 ° C. to obtain the samples shown in Table 1 below. The obtained non-porous anodic oxide film was formed at the boundary between the boehmite film and the metal substrate.
A 1% silicate aqueous solution or a 1% phosphate aqueous solution was applied to the rest of the plurality of boehmite-treated metal base materials and dried at 120 ° C. after application to obtain the samples shown in Table 1 below.

The porosity was obtained by cutting the cross section of the coating with a microtome and observing it at 100,000 times at 10 locations with a transmission electron microscope (TEM) to determine the area ratio of the pores at the boundary between the boehmite coating and the non-porous coating. And rate. The holes here are holes of about 50 to 1000 Å from the aluminum substrate to the boehmite layer. However, a portion where the intermetallic compound was present and the film was discontinuous was removed. The outline is shown in Fig. 3.
Non-porous film 7 and boehmite layer 8 on aluminum substrate 6
In the case of a structure in which and are sequentially laminated, when a plurality of holes extending from the middle part of the non-porous film 7 to the boehmite layer 8 are formed, the area of the holes is defined as C and When the area is D, the porosity (porosity) = (total area of C / D) × 100.

Next, the concentrations of Si and P were determined by glow discharge mass spectrometry (GDMS) while etching from the film surface.
The mass analysis of Si or P was performed, the thickness up to the point where the concentrations of Al and O crossed was regarded as the film thickness, and the obtained concentration values of Si or P were averaged to obtain. That is, as shown in FIG. 4, a diagram in which the horizontal axis represents the etching time and the vertical axis represents the concentration (ppm) was prepared, and the concentrations of Al, O, and Si were measured. Shown (a + b + c + d + e + f + g
+ H + j + k + l + m) / β was calculated.

[0039]

[Table 1]

A corrosion resistance test and an adhesion test were performed on each sample obtained by the above manufacturing method. Corrosion resistance test is 5
It was performed by exposing it to a humid environment having a relative humidity of 95% or more at 0 ° C. for 240 hours and comparatively observing the corrosion state of the surface. The results are shown in Table 2 below. In Table 2, the samples marked with ⊚ have no corrosion, the samples marked with ∘ have a corroded area of 5% or less of the surface area, and the marks marked Δ. The sample indicated by is a sample whose corroded area is 15% or less of the surface area, ×
The sample indicated by the mark is a sample having a corroded area of 30% or more of the surface area. For the adhesion test, take out the sample that has been subjected to the above corrosion resistance test and immediately perform a cross-cut test (1 mm with a cutter.
A test of forming 100 square cells and peeling them off with an adhesive tape was performed. The results are shown in Table 2. In Table 2, the sample marked with a circle is a sample having a peeled portion of 5% or less, and the sample marked with a cross is a sample having a peeled portion of more than 5%.

[0041]

[Table 2]

From the results shown in Tables 1 and 2, it became clear that the samples according to the present invention both show excellent corrosion resistance and coating adhesion. First, Table 1 Nos. 1-3
The sample of the thickness of the aluminum substrate is 300Å, 80
Only a porous film (boehmite film) of hydrated oxide of 00Å and 20000Å is formed, and a sodium silicate solution (Si
It is a sample obtained by immersing it in a concentration of 10000 ppm) and then drying it. When the porous film has a thickness of 300 Å, the corrosion resistance is slightly reduced, but a thicker sample (800
At 0Å and 20000Å), the corrosion resistance was excellent. The sample of No. 22 has a porous film of hydrated oxide 20
Although the sample was formed with 0Å, the result was inferior in corrosion resistance. The sample of No. 23 has a porous film of hydrated oxide 22
Although the sample was 000Å formed, many cracks were formed in the film, which resulted in poor corrosion resistance. Therefore, the porous film of hydrated oxide should be at least 3
It seems that 00Å is necessary, and conversely, when it exceeds 20000Å, cracks are generated and the corrosion resistance is inferior. Therefore, the porous film of hydrated oxide is 300
It has been found that it is preferable to form in a thickness range of Å or more and 20000 Å or less.

The samples No. 4 to No. 21 are samples provided with both a non-porous anodic oxide film and a porous film (boehmite film), and Nos. 4 to 6 are samples provided with Si by an electrolytic method. , Nos. 7 to 9 are samples to which Si is applied by the coating method, Nos. 10 to 13 are samples to which P is applied by the electrolytic method, No. 14 samples are samples to which P is applied by the coating method, No. 15 to No. 19 is a sample to which P is added by the electrolytic method, No. 21 is a sample to which Si is added by the electrolytic method, N
No. 22 is a sample to which P is added by the electrolytic method. Further, in the samples of No. 1 to No. 21, as the treated salt, sodium silicate, ammonium dihydrogen phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, aluminum dihydrogen phosphate, magnesium dihydrogen phosphate, Either dihydrogen phosphate was used. Further, a coating film having a thickness of 5 μm was formed on the samples of Nos. 20 and 21, and the coating film adhesion was also evaluated.

The sample No. 4 has a hydrated oxide film of 300.
Å, a sample with 50 Å non-porous anodic oxide film formed, but N with only hydrated oxide film formed to 300 Å thickness
The test result of the corrosion resistance is better than that of the sample of No. However, as with the No. 25 sample, the thickness is 40Å
The result was inferior to the corrosion resistance of the anodic oxide film. From the above, it is understood that the provision of the non-porous anodic oxide film contributes to the improvement of the corrosion resistance, and the thickness thereof needs to be at least 50Å. The sample of No. 8 has a Si concentration (4
It is a sample (20 ppm) in which the amount of 1000 ppm) is smaller than that of the sample of No. 6, but the corrosion resistance is slightly reduced. Further, since the sample No. 24 having the Si concentration of 18 ppm was inferior in corrosion resistance, it is considered that the Si concentration needs to be 20 ppm or more.

The sample of No. 26 was a sample using trisodium phosphate as the phosphate used in electrolysis, but the corrosion resistance was not improved. From this, as the treated salt, any of sodium silicate, ammonium dihydrogen phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, aluminum dihydrogen phosphate, magnesium dihydrogen phosphate, and dihydrogen phosphate is used. It has been found that trisodium phosphate cannot be used, although it can be used. N
The samples of o.27 and 28 have low Si concentration or P concentration (17
ppm, 18 ppm), but those having a low Si or P concentration had insufficient properties of both corrosion resistance and coating adhesion. No. 29 is a sample with a porosity of 30%, but has the same characteristics as the sample of No. 1 above, and No. 30 is a sample with a porosity of 35%, but unlike the previous example, the corrosion resistance is Deteriorated.

From the above test results, a porous film made of a hydrated oxide of aluminum having a thickness of 300 Å to 20000 Å formed on a metal substrate is provided, and the surface or the inside of the porous film has a Si film. It has been found that excellent corrosion resistance can be obtained if the aluminum material is one in which at least one of P and P is attached or contained. Next, a non-porous film having a thickness of 50Å to 700Å formed on a metal substrate, and a porous film made of hydrated aluminum oxide having a thickness of 300Å to 20000Å formed on the non-porous film. It has been found that an aluminum material comprising the above-mentioned film and containing at least one of Si and P on the surface or inside thereof has excellent corrosion resistance and excellent coating adhesion.

[0047]

As described above, the present invention comprises a porous film made of a hydrated oxide of aluminum having a thickness of 300Å to 20000Å formed on a metal substrate, and the porous film contains Si and P. Since it contains, it is possible to obtain excellent corrosion resistance. Furthermore, the present invention has a thickness of 50Å on a metal substrate.
To 7,000 Å non-porous film, and a porous film formed on the non-porous film with a hydrated oxide of aluminum having a thickness of 300 Å to 20,000 Å, wherein Si is formed on the surface or inside of the film. If it is an aluminum material containing at least one of P and P, excellent corrosion resistance and excellent coating film adhesion can be obtained.

In addition, the above P and Si are added to the film in an amount of 20 to 100.
By including 000 ppm, excellent corrosion resistance can be surely obtained, and also excellent coating film adhesion can be surely obtained. These Si and P may be applied to the surface, or may be contained or bonded in an ionic state by a method such as electrolysis, and any method can provide an aluminum material having excellent surface corrosion resistance. . If the non-porous anodic oxide film has a porosity of 30% or less, the amount of water in the inside is small, so the water is less likely to volatilize during heating, and the film is peeled off by heating during film formation. It never gets easier. Further, it has an effect of suppressing the invasion of corrosive substances, and a boehmite film can be applied as the porous film.

In the method of the present invention, a porous film of hydrated oxide is formed on a metal substrate, and silicate or phosphate is applied to this or electrolysis is performed to contain Si and P. Therefore, an aluminum material having excellent corrosion resistance can be obtained. In addition to this method,
After forming a porous film, an anodizing treatment is applied to form an anodizing film, and then Si or P can be contained by applying a silicate or a phosphate or electrolyzing. An aluminum material excellent in both corrosion resistance and coating adhesion can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of a first embodiment of an aluminum material according to the present invention.

FIG. 2 is a sectional view showing a structure of a second embodiment of an aluminum material according to the present invention.

FIG. 3 is a sectional view schematically showing a laminated structure of a second embodiment of an aluminum material according to the present invention.

FIG. 4 is a diagram for explaining a GDMS method, which is an example of a method for specifying the Si concentration of an aluminum material according to an embodiment.

[Explanation of symbols]

A, B ... Aluminum material, 1 ... Metal substrate, 2 ... Porous film, 3 ... Anodized film.

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI Theme Coat (Reference) C25D 11/18 C25D 11/18 A

Claims (8)

[Claims] 1. A metal base material made of aluminum or an aluminum alloy, and a thickness 300 formed on the metal base material.
A porous film made of hydrated oxide of aluminum having a thickness of Å to 20000Å, wherein at least one of Si and P is attached or contained on the surface or inside of the porous film. Surface-treated aluminum material with excellent corrosion resistance. 2. A metal base material made of aluminum or an aluminum alloy, and a thickness of 50Å formed on the metal base material.
To 7,000 Å non-porous film, and a porous film formed on the non-porous film with a hydrated oxide of aluminum having a thickness of 300 Å to 20,000 Å, wherein Si is formed on the surface or inside of the film. A surface-treated aluminum material having excellent corrosion resistance, characterized in that at least one of P and P is attached or contained. 3. The coating contains 2 or more of at least one of Si and P.
The surface-treated aluminum material according to claim 1 or 2, which is contained in a range of 0 ppm or more and 100000 ppm or less. 4. A non-porous anode in which the porous film made of a hydrated oxide of aluminum is a boehmite film, the non-porous film is an anodized film, and the anodized film has a porosity of 30% or less. It is an oxide film, It is characterized by the above-mentioned.
The surface-treated aluminum material according to any one of to 3. 5. A porous film made of a hydrated oxide is formed on a metal substrate made of aluminum or an aluminum alloy, and the porous film is brought into contact with or coated with an aqueous solution of silicate or phosphate to form the porous film. A method for producing a surface-treated aluminum material having excellent corrosion resistance, which comprises depositing or impregnating a coating with Si or P in the aqueous solution. 6. After forming a porous film of hydrated oxide on a metal substrate made of aluminum or aluminum alloy, anodizing treatment is applied to form a non-porous oxide film, and the film is made of silicate or phosphorus. A method for producing a surface-treated aluminum material having excellent corrosion resistance, which comprises contacting or coating an aqueous solution of an acid salt to adhere or impregnate Si or P in the aqueous solution to the coating. 7. A non-porous oxide film is formed by forming a porous film of a hydrated oxide on a metal substrate made of aluminum or an aluminum alloy and then subjecting it to anodic oxidation treatment in an aqueous silicate solution or an aqueous phosphate solution. A method for producing a surface-treated aluminum material having excellent corrosion resistance, which comprises forming and simultaneously depositing or impregnating Si or P in the aqueous solution of anodizing treatment on the coating. 8. The method for producing a surface-treated aluminum material according to claim 6, wherein the porous film is formed by boehmite treatment.