WO2004067807A1

WO2004067807A1 - Method for forming anodic oxide coating on surface of aluminum or aluminum alloy

Info

Publication number: WO2004067807A1
Application number: PCT/JP2004/000684
Authority: WO
Inventors: Yoshiyuki Mitani
Original assignee: Nihon Alumina Kakou Kabushiki Kaisha; Kirihata, Takashi
Priority date: 2003-01-30
Filing date: 2004-01-27
Publication date: 2004-08-12
Also published as: EP1593758A4; MXPA05008032A; KR20050103284A; CA2514271A1; JP4069135B2; BRPI0407080A; TW200417635A; US20070267299A1; CN1745200A; AU2004207220A1; EP1593758A1; JPWO2004067807A1

Abstract

A surface treatment method enabling to form a thick film on the surface of any kind of aluminum materials, which film is very hard and excellent in heat resistance and antibacterial properties and has a thickness of 300-500 μm, is disclosed. The method is characterized by using a bath liquid composed of a water solution containing 250-350 gr/l of sulfuric acid and 15-25 gr/l of nickel sulfate and performing anodizing under following conditions: (a) at a bath liquid temperature from -10˚C to +25˚C, (b) at a DC voltage between 100 V and 200 V, and (c) at a current density from 0.5 A/dm2 to 20 A/dm2. A low-polymerized acrylic resin composition may be added to the bath liquid within a range of 280-320 gr/l.

Description

Description Method of forming anodized film on aluminum or aluminum alloy surface

The present invention relates to an improvement in a method for forming an anodic oxide film on the surface of aluminum or an aluminum alloy. Background technology

Anodizing aluminum or its alloy in an electrolytic solution such as nitric acid, sulfuric acid, or chromic acid aqueous solution mainly to improve its corrosion resistance to form a corrosion-resistant oxide film is alumite. Known as a treatment, the alumite-treated product thus obtained is widely used in various fields, mainly for daily necessities such as pots and kettles. However, since the upper layer of the alumite film is generally porous, the corrosion resistance is still insufficient, and the abrasion resistance, the ease of coloring and the like have not been satisfactory. In order to solve such a problem, Patent Documents 1 to 3 below disclose a technique for forming a composite film of an aluminum oxide film and an acryl resin composition, and further relates to a shape of an object to be processed. A technique for forming a dense composite film in a short period of time, and a technique for improving its coloring property are disclosed.

Patent Document 1: Japanese Patent Publication No. 0 1—0 1 9 4 7 9

Patent Document 2: Japanese Patent Application Laid-Open No. H02-09976998

Patent Document 3: Japanese Patent Publication No. 0 5—0 1 4 0 3 3

However, when these surface treatment methods and other conventionally known alumite treatment methods are used, an anodic oxide film can be easily formed on an A1-Mn-based alloy, but a treatment can be performed on a duralumin-die-cast alloy. It is impossible, and there is a problem that it is difficult to treat other aluminum alloys.

Films formed by the conventional method are also relatively thin, about 30 to 50 / m in thickness, and have low hardness and other limitations. The present invention has been made to solve the above-mentioned problems, and has an object In addition to aluminum itself, it can be applied to all kinds of aluminum alloys including duralumin and die-casting alloys. Surface treatment of aluminum or aluminum alloy, which has many advantages such as high heat resistance, excellent heat resistance and antibacterial properties, and can produce various aluminum materials that can be used in a much wider range of fields than before It is to provide a method.

The above object of the present invention is to

Using a bath solution consisting of an aqueous solution containing sulfuric acid of 250 gr / 1 or more and 350 gr / 1 or less and nickel sulfate of 15 gr / \ or more and 25 grZl or less, the following processing conditions, that is,

(a) Bath temperature-10 ° C or higher, + 25 ° C or lower,

(b) Voltage 100V DC or more, 200V or less,

(c) Current density 0.5 A / dm2 or more, 20 A dm2 or less,

Can be achieved by performing anodizing treatment under the following conditions.

The above process according to the present invention is referred to as “process of the present invention (1)” for convenience of description, and the product obtained thereby is referred to as “product of the present invention (1)”. By using a bath solution to which a low-polymerized acrylic resin composition is added in the range of 280 gr / 1 to 320 gr / 1 to the bath solution used in the above treatment (1) of the present invention, The object can be achieved more suitably.

This processing according to the present invention is referred to as “present invention processing (2)” for convenience of explanation, and the product obtained thereby is referred to as “present invention product (2)”.

In the above treatment (2) of the present invention, in order to prevent so-called “burn”, a bath solution containing tartaric acid in the range of 5 gr / 1 or more and 15 gr Z1 or less may be used for the bath solution. Recommended.

When applying the method of the present invention to an aluminum alloy selected from the group consisting of duralumin, a die-cast aluminum alloy, or an aluminum alloy containing no Mn, which was difficult with a conventional surface treatment method. Uses any of the above bath solutions and the following processing conditions:

(d) Bath liquid temperature above 10 and below 1 and below 5, (e) Voltage 130VDC or more, 170V or less,

(f) Current density 8 A / dm2 or more, 12 A / dm2 or less,

It is desirable to perform the anodic oxidation treatment under the following conditions.

When performing anodic oxidation treatment on the surface of an aluminum alloy containing Mil, use one of the above bath solutions and the following treatment conditions, namely,

(g) Bath temperature + 15 ° C or higher, +18 or lower,

(h) Voltage 130VDC or more, 170V or less,

(i) Current density 8AZdm2 or more, 12A / dm2 or less,

It is desirable to perform the processing under the following conditions. In a further preferred embodiment of the present invention, after forming an anodized film on the surface of aluminum or aluminum alloy by any of the various treatment methods described above,

10 gr / 1 or more, 30 gr / 1 or less silver sulfate or silver nitrate, 15 gr / 1 or more, 20 gr / \ or less boric acid, 1 gr / 1 or more, 2 gr / 1 or less nickel sulfate Using the bath solution consisting of the aqueous solution containing

Bath temperature + 10 ° C or higher, + 20 ° C or lower,

(k) Voltage AC10V or more, 15V or less,

(1) current density lA / dm @ 2 or more, 2 A / dm ² or less,

(πι) Energization time 2 minutes or more, 3 minutes or less,

It is recommended to impregnate the anodic oxide film with silver by treating under the following conditions.

Such a process according to the present invention is referred to as “process of the present invention (3)” for convenience of explanation, and a product obtained thereby is referred to as “product of the present invention (3)”. The object of the present invention is further to form an anodic oxide film having a thickness of 300 m or more and 600 m or less on the surface of aluminum or an aluminum alloy by the above-mentioned various treatment methods, and further performing the silver impregnation thereon, The method can also be achieved by forming an anodized film on the surface of aluminum or aluminum alloy, characterized in that the surface layer is removed to a thickness of 50 m or more and 100 m or less by polishing to obtain a superhard smooth surface. Brief explanation of drawings

FIG. 1 is an explanatory view showing one embodiment of an apparatus for implementing a method for forming an anodized film on a surface of aluminum or an aluminum alloy according to the present invention. FIG. 2 is an enlarged sectional view of a portion to be coated with aluminum or an aluminum alloy which has been subjected to the treatment (2) of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be specifically described with reference to the drawings and the like.

In FIG. 1, 1 is an electrolytic cell, 2 is an AC power supply, 3 is an aluminum or aluminum alloy member to be treated by the method of the present invention, 4 and 4 are non-consumable electrodes such as rubber and graphite, 5 Is a bath solution composed of a predetermined electrolytic solution.

In the treatment (1) of the present invention, an apparatus as shown in Fig. 1 was used, and as a bath solution, sulfuric acid of 250 gr / 1 or more and 350 gr / l or less, and 15 gr / 1 or more and 25 gr / 1 or less Using an aqueous solution containing sulphate nigel,

(a) Bath temperature -10 ° C or higher, +25 or lower,

(b) Voltage 100V DC or more, 200V or less,

(c) Current density 0.5 Adm2 or more, 20 Adm2 or less,

The anodizing treatment is performed under the conditions described above.

Thus, the present invention is completely different from the conventional method in that the anodic oxidation treatment is performed under the processing conditions of high sulfate ion concentration, low temperature, and high current density.

If each numerical value of the above processing conditions is less than the lower limit value, the processing efficiency is poor, and if it exceeds the upper limit value, the hardness of the coating film is reduced and a desired film thickness cannot be obtained. You.

Nigel sulfate is added to improve the hardness of the formed film. Examples of the aluminum or aluminum alloy material forming the anodic oxide film by the treatment method of the present invention include those listed in Table 1 below. table 1

In addition, when the method of the present invention is applied to durlumin, an aluminum alloy for die casting, a difficult-to-treat aluminum alloy such as an aluminum alloy containing no Mn, and other aluminum alloys, which were difficult with the conventional method, Using any of the above bath solutions, the following processing conditions:

(d) Bath temperature -10 ° C or higher, _5 ° C or lower,

(e) Voltage 130VDC or more, 170V or less,

() Current density 8AZdm2 or more, 12Adm ^ or less,

On the other hand, when the anodic oxidation treatment is performed on the surface of the aluminum alloy containing Mn, the following treatment conditions, that is,

(g) Bath temperature + 15 ° C or higher, +18 or lower,

(h) Voltage 130VDC or more, 170V or less,

(i) the current density 8A / dm ² or more, 12 A / dm ² or less,

By adopting the condition, a desired anodic oxide film can be _formed.c When the present invention configured as described above is compared with the conventional method, the following advantages can be obtained.

(1) With the conventional method, an anodic oxide film could be easily formed on A1-Mn alloys, but it was not possible to treat duralumin and die cast alloys, and to treat other alloys. Was difficult.

On the other hand, the method of the present invention can be applied to all kinds of aluminum alloys such as duralumin, die cast alloys and the like.

(2) In the conventional method, only a film having a thickness of about 30 to 50 im, at most about 100 m can be formed, but according to the method of the present invention, a thick film of 300 to 500 m can be easily formed. .

(3) The film formed by the conventional method has a hard surface layer (however, a Pickers hardness of 400 or less), but has a porous inside and low hardness.

On the other hand, the coating formed by the method of the present invention has a high surface hardness and a Vickers hardness of about 450 to 500. In particular, the lower layer is denser and harder than the surface, and when removed from the surface by 50 to 150 m, the Vickers hardness becomes 800 to 1000.

(4) The film formed by the method of the present invention has high thermal conductivity, which is comparable to that of copper.

(5) The coating formed by the method of the present invention has low surface heat transmission resistance.

Thus, when ice is placed on a tray made of aluminum or an alloy thereof having a coating formed by the method of the present invention, the ice melts twice as fast as an untreated tray. Therefore, for example, it can be suitably used as a tray for thawing frozen foods. In addition, when the aluminum heating container for popcorn is treated by the method of the present invention, the time from the start of heating to the first explosion of the popcorn is reduced from 6 minutes of the conventional product to 3 minutes.

(6) The film formed by the method of the present invention has a high heat resistance and is about 800 ° C. (7) The film formed by the method of the present invention has antibacterial properties.

Therefore, the aluminum material or aluminum alloy material on which the anodized film is formed by the method of the present invention is, for example, a tray for ice making and thawing, a rice cooker, a pot, a pot, a kettle, other heating cookers, and an instantaneous boiling water. Heaters, heat exchangers, air conditioners, refrigerators, refrigerators, oil heaters, radiators, cooling fins, air-cooled and water-cooled engines (promoting heat dissipation), Aircraft wings (anti-icing), semiconductor heat dissipation boards, semiconductor packages, heat pipes, bearings, various sliding members, brake shoes, popcorn and ice cream manufacturing equipment, electrical equipment chassis, motors and transformers It can be suitably used in a wide range of fields, such as singles and so on.

These use the property that the product of the present invention conducts heat well. Next, the process (2) of the present invention will be described.

In the case of performing the treatment (2) of the present invention, a low-polymerized acrylic resin composition is further added to the bath used in the treatment (1) of the present invention in a range of 280 gr / 1 or more and 320 gr / 1 or less. Anodizing treatment is performed using the added bath solution.

Examples of the low-polymerized acrylic resin composition to be added include, for example, 68% of hydroxypropyl methacrylate, 10% of neopentyl dalichol dimethacrylate, 19.5% of polypropylene glycol methyl acrylate, and 6 Hexanediol diglycidyl ether 1%, butyl peroxyctoate 1%, hydroquinone monomethyl ether 500ppra, and dicyandiamide 0.3% are preferably used.

For the purpose of preventing "burn", it is recommended that tartaric acid be further added to the above bath solution in a range of 5 gr / 1 or more and 15 gr / 1 or less.

By the treatment (2) of the present invention, an oxide film in which aluminum oxide and the acrylic resin composition are combined is formed. That is, since the porous oxide film on the metallurgy and the acrylic resin fabric are polymerized by acid ionization to form a strong and dense composite film, the corrosion resistance and the abrasion resistance are greatly improved. In addition, since the film is generated while evacuating the gas from the pinholes, the number of pinholes is extremely small. Furthermore, the oxide film is formed slowly at low temperatures, so it has excellent denseness and the film is hard to peel off, so it is machined. And the surface roughness does not change.

The anodic oxide film obtained by the treatment (2) of the present invention will be described with reference to an enlarged cross-sectional view of the film in FIG.

In FIG. 2, reference numeral 21 denotes a base metal aluminum or aluminum alloy material, 22 denotes an anodized film, 23 denotes a barrier layer thereof, 24 denotes a porous film portion, and 25 denotes an acrylic resin composition film portion. You.

The anodic oxide film 22 is composed of a barrier layer 23 formed on an aluminum material or an aluminum alloy material 21, a porous film portion 24 formed thereon, and an acryl resin composition penetrated and fixed in the porous layer. And a coating layer 25. A strong and dense composite coating is formed by the coating layers 24 and 25. Since the hardness of the composite coating increases as the portion is closer to the barrier layer 23 and becomes denser, a region closer to the surface can be removed by machining to obtain a surface with higher hardness as described later. Next, the process (3) of the present invention will be described.

In the case of performing the treatment (3) of the present invention, after forming an anodic oxide film on the surface of the aluminum or aluminum alloy by any of the above-mentioned various treatment methods, it is further treated at least 10 gr / \ and 30 gr / Using a bath solution consisting of an aqueous solution containing silver sulfate or silver nitrate of 1 gr or less, boric acid of 15 gr / 1 or more and 20 gr gr or less, and nickel sulfate of 1 gr / 1 or more and 2 gr / 1 or less, the following Processing conditions, ie,

(j) Bath temperature + 10 ° C or higher, + 20 ° C or lower,

(k) Voltage AC10V or more, 15V or less,

(1) current density lA / dm ² or more, 2 A / dm @ 2 or less,

(m) Energization time 2 minutes or more, 3 minutes or less,

By performing anodic oxidation treatment under such conditions, silver is impregnated in the anodic oxide film.

The decrease in silver ion concentration with the progress of processing is compensated for by replenishment of silver sulfate or silver nitrate.

Boric acid is mainly added for adjusting the conductivity of the electrolyte.

If the voltage is less than 10 V, the processing efficiency is poor.If the voltage is more than 15 V, silver is deposited too rapidly, so that the porous layer of the oxide film is not sufficiently impregnated. Easily occur.

Similarly, if the temperature of the electrolytic solution is lower than + 10 ° C, the processing efficiency is poor, and if it exceeds + 20 ° C, color unevenness is likely to occur.

By the treatment (3) of the present invention, silver ions are formed in the porous anodic oxide film. Penetrates deeply (electrolytically impregnated by AC voltage), and forms a strong and dense composite film by combining with aluminum oxide, so the surface has excellent thermal conductivity, corrosion resistance, abrasion resistance, antibacterial properties, etc. A coating is formed. The surface coating is conductive, has a low coefficient of friction on the surface, and has little change in color over time. It also has the effect of generating far infrared rays and removing static electricity.

The treatment (3) of the present invention can be applied to all aluminum materials or aluminum alloy materials, and a thick film having the above-mentioned various excellent properties can be formed on the surface thereof. The present invention further provides an anodic oxide film having a thickness of not less than 300 m and not more than 600 im on the surface of aluminum or an aluminum alloy by the above various treatment methods, and further performing the above silver impregnation thereon. The present invention provides an aluminum material or an aluminum alloy material having a superhard smooth surface by removing a surface layer from 50 / xm to 100 m by polishing.

That is, the coating formed by the method of the present invention has a high surface hardness, and has a Vickers hardness of about 450 to 500. In particular, the lower layer is denser and harder than the surface. Therefore, removing 50 to 50 L from the surface gives an aluminum or aluminum alloy material with a smooth surface with a Vickers hardness of 800 to 1000, which is very hard. Hereinafter, various characteristics of the product of the present invention will be described.

Table 2 shows the properties of the products treated according to the present invention for each material.

General Al This invention

Mite film Thickness Silver impregnation Hardness Thermal conductivity Antibacterial Antibacterial smoothness

AL00 series Δ 60 Z Possible 450 Significant increase Yes 2, 5

ALIO system Δ 60 OK 450 Significant increase Yes 2, 5

AL20 series X 60W OK 450 Significant increase Yes 2, 5

AL30 series Δ60 OK 450 Significantly increase Yes 2, 5

AL40 series Δ60i Possible 450 Significant increase Yes 2, 5

AL50 series ◎ lQQii Yes 450 Significant increase Yes 2, 5

AL60 series ◎ 100 i Possible 450 Significant increase Yes 2, 5

AL70 series Δ60 x OK 450 Significant increase Yes 2, 5

AL80 series Δ60 OK 450 Significantly up Yes 2, 5

AC2 Δ OK 370 Significantly up

AC3 Δ60M OK 370 Significantly up

AC4 Δ 60 OK 370 Significantly up

AC7 Δ 60 OK 370 Significantly up

ADC1 X 30/2 OK 370 Significant increase Yes

ADC5 X 30 OK 370 Significantly up

ADC8 X 30M OK 370 Significantly up Yes

ADC12 X 30 ^ Possible 370 Significantly up

(Note)

General alumite symbol X Cannot be processed

Δ difficult to process

® Easy processing The thermal conductivity is 0.9 for the product of the present invention, 0.94 for copper, and 0.53 for aluminum, assuming that silver is 1. Therefore, the thermal conductivity of the product of the present invention is higher than that of aluminum of the base material and about the same as that of copper.

This property indicates that it is excellent as a material for various heat transfer members, heat transmission members, and heat radiation members.

The hardness (Hv) is 80 for aluminum, 200 for stainless steel, and 450 for the product of the present invention, and the product of the present invention has twice or more the hardness of stainless steel.

Utilizing this property, gears, rollers, guide rails, shafts, bearings, brake shoes, cylinder liners and pistons, valves, piston pumps, screw pumps ^

It can manufacture various parts that require wear resistance, such as pumps.

The heat resistance temperature (t :) is 260 ° C for polytetrafluoroethylene, 660 ° C for aluminum, and 800 ° C for the surface coating of the product of the present invention.

By utilizing this property, a fireproof shutter, a heat-resistant wall material, and the like can be provided. As a result of the abrasion test, the amount of abrasion of the product of the present invention was 1 Z10 of ordinary hard alumite.

That is, an abrasion test was performed with the test piece on the rotating side and the resin-based oilless bearing material on the fixed side. The test conditions were a vibration speed of 1 mZs, a surface pressure of 20 kgf cm2 and a test time of 3 hr. As a result, the wear amount of the hard anodized was 2.5 m, and the wear amount of the product of the present invention was 0.25 m. As a result of a seizure test, the seizure surface pressure of the product of the present invention was twice that of ordinary hard alumite.

That is, as a seizure resistance test, the wear coefficient was measured with the test piece on the rotating side and the resin-based oil-free bearing material on the fixed side, and the load at which the wear coefficient increased sharply was evaluated as the seizure limit load. In contrast, ordinary hard alumite was 160 kgf / cm2, whereas that of the product of the present invention was 320 kgf / cm2. When the progress of cracks was measured by a high-temperature test, the product of the present invention showed that the initial cracks were smaller than that of Tafram (trade name; a product in which hard alumite was sintered and impregnated with polytetrafluoroethylene). The number of cracks increased by heating was small.

That is, when the number of cracks in the measured area of the flat portion of 16.4 nmi ² was measured, the product of the present invention was 0 before heating, but became 12 after heating, whereas the evening flam was before heating. From 263 to 321 after heating. An antibacterial test was performed. The contents are as follows.

(a) Specimen Sample 1 ·· Aluminum Surface treated product by silver impregnation treatment of the present invention

(Surface coating thickness 25μπΐ)

Specimen 2

(b) Test purpose

Conduct an antibacterial test on the sample.

(c) Test outline

Escherichia coli, Staphylococcus aureus, Vibrio parahaemolyticus, and Salmonella were each added dropwise to a sample (hereinafter referred to as “sample”), and the viable cell count of the sample after storage at 35 ° C. for 24 hours was measured.

(d) Test method

i) Test bacteria

Escherichia coli IFO 3301 (E. coli)

Staphylococcus aureus IFO 12732 (Staphylococcus aureus)

Vibrio parahaemolyticus RIMD 2210100 (Vibrio parahaemolyticus)

Salmonella enteritidis IFO 3313 (Salmonella)

ii) Medium

NA medium: normal agar medium

NB medium: normal broth medium supplemented with 0.2% meat extract

SA medium: Standard agar medium

iii) Preparation of bacterial solution

After the test bacteria were cultured in NA medium at 35 ° C for 16 to 24 hours, they were inoculated again into NA medium and cultured at 35 ° C for 16 to 20 hours. After the cultivation, so Nigosa suspended bacterial cells obtained test bacteria to 1 Z200 concentration NB medium, appropriately diluted with 1/200 concentration NB medium so that the number of bacteria is 10 ⁵ to 10 ⁶ ml, was used as a cell solution . However, for Vibrio parahaemolyticus, an NA medium and a 1Z200 concentration NB medium supplemented with 3% of sodium chloride were used.

iv) Sample preparation

The test surface of the sample was gently wiped with absorbent cotton containing 99.9% (V / V) ethanol, and then thoroughly dried.

V) Test operation 0.5 ml of the bacterial solution was added dropwise to the sample, and a polyethylene film was adhered to the sample. The solution was stored at 35 ° C, and the number of viable cells after storage for 24 hours was measured. Also, 0.5 ml of the bacterial solution was dropped on a plastic dish, and a polyethylene film was adhered to the sample, which was used as a control sample for the same test. The trial was performed three times in parallel measurement.

vi) Measurement of viable cell count

Each sample was washed out with 9.5 ml of SCDLP medium [Nihon Pharmaceutical Co., Ltd.]. The number of viable bacteria was measured by a pour plate method (cultured at 35 ° C. for 48 hours) using an SA medium and converted to a sample. However, for Vibrio parahaemolyticus, SCDLP medium and SA medium supplemented with 3% of salt were used.

(e) Test results

The measurement results of the viable cell count of the test bacteria dropped on the sample were as shown in Table 3 below.

* 1 Bacterial suspension: 1/200 concentration NB medium (However, for Vibrio parahaemolyticus, 3% salt was added.) * 2 Plastic Petri dish

Φ 3 1 1): This means that no bacteria were detected by the bacterial counting method used in this test. Table 4 below shows the treated products according to Patent Documents 1 and 2 as comparative examples (Yufu Coat) : Product name) and processed products according to Patent Document 3 (Metal coat: Product name) Have been. These results are remarkably superior to those of other known products, but all of them are inferior to the above-mentioned products of the present invention.

Table 4

Industrial applicability

Since the present invention is configured as described above, according to the present invention, the following operation and effect can be achieved as described above.

(1) According to the conventional method, an anodic oxide film could be easily formed on A1-Mn alloy. Duralumin and die casting alloys could not be treated, and other alloys were difficult to treat.

(2) In the conventional method, a film having a thickness of only about 30 to 50 / m, at most about 100/2 m can be formed, but according to the method of the present invention, a thick film of 300 to 500 m can be easily formed. Can be formed.

On the other hand, the coating formed by the method of the present invention has a high surface hardness and a Vickers hardness of about 450 to 500. In particular, the lower layer is denser and harder than the surface, and when removed from the surface by 50 to 150 m, the pickers hardness becomes 800 to 1000.

Thus, when ice is placed on a tray made of aluminum or an alloy thereof having a coating formed by the method of the present invention, the ice melts twice as fast as an untreated tray. Therefore, for example, it can be suitably used as a tray for thawing frozen foods. In addition, when the aluminum heating container for popcorn is treated by the method of the present invention, the time from the start of heating to the first explosion of the popcorn is reduced from 6 minutes to 3 minutes of the conventional product.

(6) The film formed by the method of the present invention has a high heat resistance and is about 800 ° C.

(7) The film formed by the method of the present invention has antibacterial properties. Therefore, as described above, the aluminum material or the aluminum alloy material on which the anodized film is formed by the method of the present invention is, for example, a tray for ice making and thawing, a rice cooker, a pot, a pot, a kettle and other heating cookers, Water heaters, heat exchangers, air conditioners, refrigerators, refrigerators, oil heaters, radiators, cooling fins, air-cooled and water-cooled engines (promoting heat dissipation), aircraft wings (anti-icing prevention), semiconductor heat dissipation boards, Semiconductor packages, heat pipes, bearings, various sliding members, plastics, popcorn and ice cream It can be suitably used in a wide range of fields, such as manufacturing equipment, electrical equipment chassis, motors and casings for transformers, etc.

Claims

The scope of the claims

1. Using an aqueous solution containing an aqueous solution containing sulfuric acid of 250 gr / 1 or more and 350 gr / 1 or less and nickel sulfate of 15 gr / 1 or more and 25 gr / 1 or less, anodizing under the following conditions Forming an anodized film on the surface of aluminum or an aluminum alloy.

(a) Bath temperature-10 ° C or higher, + 25 ° C or lower,

(b) Voltage 100V DC or more, 200V or less,

(c) Current density 0.5 A / dm2 or more and 20 A / dn ^ or less.

2. Anodizing the surface of aluminum or aluminum alloy according to claim 1, further comprising using a bath solution containing a low-polymerized acrylic resin composition in a range of 280 grZl or more and 320 grZl or less. A method of forming a coating.

3. An anode or aluminum alloy surface according to claim 1 or 2, wherein a bath solution to which tartaric acid is added is used in a range of 5 gr / 1 or more and 15 gr / 1 or less. A method of forming an oxide film.

4. The method for forming an anodized film on a surface of aluminum or an aluminum alloy according to claim 1, wherein anodizing treatment is performed under the following conditions.

(d) Bath temperature-10 ° C or higher, 1-5 or lower,

(e) Voltage 130VDC or more, 170V or less,

() Current density 8AZdm2 or more, 12A / dm2 or less.

5. An anodic oxide film is formed on the surface of the aluminum alloy according to claim 4, wherein the aluminum alloy to be treated is an aluminum alloy selected from the group consisting of duralumin, an aluminum alloy for die casting, and an aluminum alloy containing no Mn. how to.

6. The method for forming an anodized film on the surface of an aluminum alloy according to claim 1, wherein anodizing treatment is performed on the surface of the aluminum alloy containing Mn under the following conditions. .

(g) Bath temperature + 15 ° C or higher, +18 or lower,

(h) Voltage 130VDC or more, 170V or less,

(i) Current density 8 AZdm ² or more, 12 AZdm ² or less.

7. After forming an anodic oxide coating on the surface of aluminum or aluminum alloy by the method according to any one of claims 1 to 6, 10 gr / 1 or more and 30 gr / 1 or less of silver sulfate or silver nitrate. An aqueous solution containing boric acid of 15 gr / 1 or more and 20 gr / 1 or less and nickel sulfate of 1 grZ 1 or more and 2 gr / 1 or less is used in the anodic oxide film under the following conditions. A method for forming an anodic oxide film on a surface of aluminum or an aluminum alloy, wherein the method comprises impregnating silver.

(j) Bath temperature + 10 ° C or higher, + 20 ° C or lower,

(k) Voltage AC10V or more, 15V or less,

(1) Current density lAZdm2 or higher, 2 A / dm2 or lower,

(m) Energization time 2 minutes or more, 3 minutes or less.

8. A method according to any one of claims 1 to 6, wherein an anodic oxide film having a thickness of 300 m or more and 600 m or less is formed on the surface of aluminum or aluminum alloy, and the silver according to claim 7 is formed. A method of forming an anodic oxide film on the surface of aluminum or an aluminum alloy, comprising removing the surface layer from 50 xm to 100 m by polishing after impregnation to obtain a superhard smooth surface.