JP2002161397A - Metal compact coated with anodic oxide film containing microparticle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal compact superior in durability and corrosion resistance, which keeps an adequate wettability for a long time. SOLUTION: The metal compact composed of a metal with an oxide film formed on the surface by anodizing is characterized by that microparticles are included in the oxide film and the exposed microparticles over the oxide film occupy 20% or more of the metal surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an oxide film formed on a metal surface. More specifically, the present invention relates to a metal molded body on which an oxide film having unevenness of an oxide film formed on a metal surface is formed.

[0002]

2. Description of the Related Art Metals such as Al, Ta, V, Nb, Ti, and Si exhibit a rectifying action in an aqueous solution by being covered with an oxide film by anodic oxidation, and are generally called valve metals (valve metals). An oxide film is actively formed.
Research on valve metal anodic oxidation has been carried out vigorously since about 1930. Particularly from around 1980, significant progress has been made in aluminum, stainless steel and titanium. By forming an oxide film of several hundred nm mainly by anodic oxidation, metal can be colored in various shades by light interference, and a colored film or hard film is generated, improving decorative and functional value It is mainly applied because it is possible to make it possible. In addition, these metals are attracting attention because they can form a porous oxide film by performing anodic oxidation using a solution having an etching action such as sodium hydroxide as an electrolyte, and have been reported in numerous documents and patents. There is.

[0003] It is reported that a titanium oxide film obtained by oxidizing titanium is generally stable in an inorganic acid, and a dense and smooth oxide film is formed even when anodizing is performed. On the other hand, the anodic oxidation in a strongly basic aqueous solution suggests the formation of a porous body, and is described in “Electrochemistry,
68 (2) P. 106 (2000) ", it is reported that a porous oxide film is formed using sodium hydroxide as an electrolyte. Aluminum is also dense when anodized using a neutral electrolyte, the resulting aluminum oxide film becomes denser, but when anodized under acidic etching conditions in an acidic electrolyte, it becomes porous. It is reported in "Chemistry and Education, 47 (8) P.520 (1999)" that anodized porous alumina can be obtained.

[0004] Also, in the case of titanium, it is known that by applying an overvoltage when forming a thick anodic oxide film on the surface of titanium, the oxide film is made porous under the condition of a spark generation voltage or higher. P. 49 (198
9)). Techniques related to anodic oxidation include, for example, JP-A-52-16198 and JP-A-51-1981.
-26567, JP-A-52-10696,
JP-A-52-22534, JP-A-52-1202
No. 37 and Japanese Patent Application Laid-Open No. 11-217693 describe a technique of anodizing a metal plate. However, the technique uses an interference color obtained by light interference when the thickness of an oxide film is simply controlled. It was for obtaining a decorative effect.

A technique for improving the wettability and adhesion between a metal and a plastic sheet or a polymer solution is disclosed in
JP-A-3-139724 describes that metal oxides or cemented carbides are coated by explosive spraying or plasma spraying to increase the adhesion. JP-A-03-219928 discloses a cooling roller for casting a resin.
A method is described in which the diameter of a nozzle is defined and air entrapment when a thermoplastic resin is cast at a high speed is suppressed.

[0006] JP-A-09-155952 discloses that a polyamide resin is extruded onto a roughened rotating cooling roll,
A method for producing at high speed is described. JP-A-58-
JP-A-63415 describes a method in which a cooling roll is subjected to a sandblasting or etching treatment, and further a polymer sheet is brought into close contact with the surface of the quenching roll through a liquid coating such as water. . JP-A-10-3215
No. 59 and Japanese Patent Application Laid-Open No. Hei 10-127958 describe a method for forming large irregularities and small irregularities simultaneously by subjecting a metal surface such as aluminum or titanium to a surface roughening treatment by a sandblasting method and then anodizing. I have.

All of the above methods increase the surface area by physically roughening the surface with a method such as sand blasting or chemically roughening the surface with a solution of sodium hydroxide, sulfuric acid, hydrofluoric acid or the like. However, it is difficult to control the rough surface by the method of physically roughening, and irregularities of several tens μm to several hundred μm are formed. When used as a cooling roll or belt at the time of cleaning, the irregularities are transferred to the product. The method of roughening the surface by etching with a solution has a disadvantage that the metal absorbs ions such as hydrogen and cannot maintain the original strength of the metal.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a metal molded body which can maintain good wettability over a long period of time and has excellent durability and corrosion resistance.

[0009]

Means for Solving the Problems The present inventors carry out anodic oxidation of a metal in the presence of fine particles, whereby fine particles are included in the anodic oxide film, and the fine particles are formed only by performing anodic oxidation. Anodized film having various projections is obtained, and further, the film has a very high wettability of 50 dyne / cm or more.
The present invention has been completed.

That is, the present invention provides (1) a metal molded article having an oxide film formed on the surface by an anodizing method, wherein the oxide film contains fine particles, and 20% of the surface of the oxide film (2) a metal molded body characterized in that the above is occupied by fine particles exposed from the oxide film.
The metal molded body according to (1), wherein the surface of the oxide film has a wetting index of 50 dyne / cm or more,
(3) The metal molded body according to (1) or (2), wherein the thickness of the oxide film is 1 nm or more, (4)
The metal molding according to (1), (2) or (3), wherein the fine particles are silica, titanium oxide or alumina.

Hereinafter, the present invention will be described in detail. The present invention is to form fine particles in the electrolytic solution in the process of forming the oxide film by the anodic oxidation method, to capture the fine particles in the oxide film, to positively form irregularities on the oxide film surface, The wettability is further improved by exposing the fine particles to each oxide film. The metal molded body of the present invention, titanium, zirconium, ruthenium, iron, zinc, tantalum, copper, aluminum, niobium, nickel, lead, chromium, tungsten, magnesium, any one of manganese, or at least one of these metals The base material is an alloy containing 50% by weight or more of one kind.

The metal molded article of the present invention may be a solid, such as a plate, a rod, or a sphere, of the above-mentioned metal, or a plate formed by coating the above-mentioned metal by plating, vacuum deposition, sputtering, or the like. An anodic oxidation is carried out on a solid state such as a rod, a sphere or the like in the presence of fine particles in the electrolyte described in the present invention to form an oxide film on the metal surface, and the oxide film Containing microparticles inside,
Further, fine particles are exposed on the surface of the oxide film.

The fine particles in the present invention may be those which are negatively charged in the electrolyte. For example, colloidal silica,
Examples thereof include silica such as fumed silica, tantalum oxide, titanium oxide, zeolite, alumina, aluminum hydroxide, aluminum silicate, iron oxide, and aluminum. Among them, colloidal silica, titanium oxide, and alumina are preferably used. Although it is generally possible to negatively charge these particles only by adjusting the pH, there is no problem even if coupling treatment or addition of a surfactant is performed. The charged state of the fine particles can be confirmed by measuring the zeta potential. For example, ELS-8 manufactured by Otsuka Electronics Co., Ltd.
It can be measured using a 00 laser potentiometer. In this measurement, usually, those charged to less than 0 mV and to about -70 mV can be preferably used.

As the electrolytic solution for performing anodic oxidation, a solution in which these fine particles are dispersed in a solvent is used. The solvent is not particularly limited as long as it does not dissolve the above-mentioned fine particles. Generally, sulfuric acid, phosphoric acid, nitric acid, sodium hydroxide, or the like that can be used for anodic oxidation is diluted with water or water is used. And methanol and ethanol which are soluble in these solvents without departing from the spirit of the present invention.
, N-propanol, acetone, isopropanol,
Organic solvents such as ethylene glycol, ethylene glycol-mono-n-propyl ether, dimethylacetamide, methyl ethyl ketone, xylene, n-butanol, and methyl isobutyl ketone can be used together, and inorganic salts can be used. Can be dissolved in a solvent in advance.

As the colloidal silica which is a fine particle that can be preferably used in the present invention, commercially available colloidal silica such as SI-80P or SI-80P can be used.
-45P, SI-50, etc. (Catalyst Kasei Kogyo Co., Ltd., trade name)
And ST-XL, ST-YL, ST-ZL, ST-20,
ST-50, ST-Ol, MP1040, MP204
0, MP-4045, etc. (trade name, manufactured by Nissan Chemical Industries, Ltd.). Colloidal silica has an isoelectric point of pH = 3
~ 4, and can be negatively charged by adjusting to be more alkaline than this. Each of the above-mentioned colloidal silicas is mainly composed of water, and is usually adjusted to an alkaline pH of about 7 to 10 by adding a very small amount of alkali such as sodium hydroxide, and has a negative charge on the surface of the particles. A high degree of dispersibility is maintained. SI4
30 μl of each of 5P, SI80P, and MP2040 was diluted with 20 ml of distilled water. The pH of the diluted solution is adjusted using an aqueous solution of hydrochloric acid or an aqueous solution of sodium hydroxide, and the electrophoretic light scattering photometer ELS-800 manufactured by Otsuka Electronics Co., Ltd. is used. A potential measurement was performed. FIG. 8 shows the results. In any case, the pH is -40 to -50 m in the range of 5 to 9.
V, indicating that the surface of the particles is negatively charged.

The silica surface has countless silanol groups and has a high affinity for water, and the use of these particles in the present invention significantly improves the wettability of the metal surface with water. Similarly, as the fine particles that can be preferably used in the present invention, commercially available titanium oxide can also be used, for example, STS-01 and STS-01.
S-02, STS-21, etc. (trade name, manufactured by Ishihara Sangyo Co., Ltd.) can be used. Titanium oxide is generally known as a photocatalyst and has a high affinity for water, and the use of these particles significantly improves the wettability of a metal surface with water.

The concentration of the fine particles contained in the electrolyte is not particularly limited, but is generally 0.001% by weight or more, preferably 0.01% by weight, in order to obtain good wettability.
The content is more preferably 0.1% by weight or more. The upper limit of the concentration is not particularly limited, but is substantially about 70% by weight.

The average particle size of the fine particles used in the metal molded article of the present invention is preferably from 1 nm to 1 μm, more preferably from 5 nm to 800 nm, further preferably from 20 nm to 500 nm. If it is smaller than 1 nm, it will be completely taken into the oxide film, or if it is partially exposed, the contact area with the oxide film will be extremely small, so that it will easily fall off. Conversely, if it is larger than 1 μm, it will settle in the anodizing process, dispersing and electrophoresis during anodizing will not be possible, and it will not be suitable because it will be too large when used as a metal molded body. These fine particles have an average particle size of 1 nm to 1 μm regardless of whether they have a single particle size or have a plurality of particle size distributions.
It does not matter if it is within the range of m. The average particle size of the fine particles is
The electrolyte containing the fine particles is diluted to about 0.5% with distilled water in advance, and the solution is placed on a grid for microscopy with a collodion film using a nebulizer, and the transmission electron microscope (TE) is used.
M) can be easily calculated from the particle image obtained. There is no particular limitation on the shape of the fine particles, and any shape such as a sphere or a needle can be used. In the case of a distorted shape, the maximum length is used as the particle size, and the average particle size is determined.

In the present invention, the oxide film surface means the entire surface including the surface of the fine particles exposed from the oxide film. The surface of the fine particles exposed to the surface of the oxide film formed on the metal surface greatly affects the wetting index, and it is necessary that at least 20% of the surface of the metal molded body is occupied by the fine particles exposed from the oxide film. , More preferably at least 30%, even more preferably at least 35%. Only when at least 20% of the surface is occupied by microparticles is a wetting index of 50 dyne / cm achieved.
The ratio of the surface of the exposed fine particles to the oxide film can be easily obtained by observing the surface of the oxide film by SEM. For example, the ratio of the exposed particles per square micrometer is calculated. At this time, most of the particles are exposed, and those in which the lower part of the particles are partially embedded in the oxide film are observed brightly white when observed by SEM. As the particles are embedded in the oxide film, the particles are gradually observed to be darker black, and those where only a part of the particles are exposed are observed to be almost black. This is apparently because the reflected electrons decrease with respect to the irradiation electrons at the time of SEM observation as the particles are incorporated into the oxide film. Particles that fall off and leave only holes on the oxide film are observed as black as particles with only a small portion exposed, but the difference between holes and embedded particles usually enhances contrast during SEM observation It is easily determined by doing Further, particles which are completely taken into the oxide film and are not exposed at all are not observed by SEM observation from the surface.

The metal molded body of the present invention has a surface wetting index of at least 50 dyne / cm, preferably at least 55 dyne / cm, more preferably at least 60 dyne / cm. 50dyne /
If it is less than cm, the effect of including the fine particles is not sufficient. The wetting index in the present invention is used as a scale that quantitatively indicates the degree of hydrophilicity, and is defined by JIS K6768.
The method used as "Plastic-film and sheet-wet tension test method" can be conveniently used as a method for evaluating the wettability of the surface of a metal molded product in the present invention. That is, in this measuring method, a series of mixed liquids having different surface tensions in sequence are applied to the surface of the metal molded product, and the surface tension (dyne / cm) of the mixed liquid determined to wet the surface is obtained. Represents
This value is called the wetting index. This wetting index is referred to as "critical surface tension".
ion) "in the field of surface science. Generally, the surface of a cleaned smooth chrome plating, nickel plating, stainless steel, tantalum or the like has a wetting index of 34 to 35 dyne / cm. According to this measurement method, pure water is the test mixture having the highest surface tension and 73 dyne / cm as the wettability index of the mixture, but in the method of the present invention, the metal molded product exhibiting more wettability is used. Surfaces can also be created.

The anodic oxidation is performed in the electrolytic solution at a DC constant current density of several milliamps to several hundreds of milliamps. When a predetermined voltage is reached, the anodic oxidation is switched to a constant voltage until the current substantially stops flowing. When the voltage is switched to the constant voltage, a phenomenon in which the current density sharply drops is recognized, and it can be seen that the denseness of the formed film is increased. The thickness of this oxide film is determined by the voltage at the time of switching to a constant voltage during anodic oxidation.
An oxide film of about 6 nm is formed, but this value varies depending on the material of the metal. Since the film thickness changes continuously by changing the voltage, an extremely large number of colors can be obtained.

When performing the oxidation treatment, a degreasing treatment is generally performed in advance for the purpose of obtaining a uniform film, and this is preferably applied also in the present invention. The degreasing treatment removes oils such as rolling oil adhering to the surface of the material, for example, ethanol, methanol, acetone,
Organic solvents such as N-methylpyrrolidone and trichloroethylene and inorganic aqueous solutions such as sulfuric acid, nitric acid, hydrochloric acid and hydrofluoric acid can be preferably used.

A metal intended for anodic oxidation is an anode (+ electrode) and a stable electrode such as carbon is a cathode (-electrode).
When a voltage is applied as the pole, hydrogen is generated from the cathode, whereas no oxygen is generated from the anode, and an oxide film is formed on the metal surface. Since the oxide film to be formed is insulative, ions must move in the oxide film in order for the film to grow. Most of the voltage applied at the time of anodization is applied to the oxide film portion having high resistance, but since the oxide film is extremely thin, about several nm to several hundred μm, the voltage converted to unit thickness is extremely large. . For example, when a voltage of 20 V is applied to a 20 nm oxide film, the electric field applied to the film is 1
It becomes a very large value of 0 ⁷ V / cm. Under such a high electric field, both O ²⁻ ions and ions of the metal to be anodized can move in the film, and the film grows. The ease of movement (transport number) of metal atoms at this time differs depending on the type of metal to be anodized, and therefore, the thickness of the oxide film per voltage varies depending on the material.

In anodic oxidation, an oxidation reaction takes place at the anode electrode, and the hydroxyl groups present in the electrolyte migrate to the anode electrode, causing the oxidation reaction to release electrons. For example, it is considered that the following reaction proceeds in titanium or tantalum. Ti + 4OH ⁻ → TiO ₂ + 2H ₂ O + 4e ⁻ 2Ta + 10OH ⁻ → Ta ₂ O ₅ + 5H ₂ O + 10e ^- As described above, an oxidation reaction occurs at the anode electrode. Absent.

When fine particles are present in the electrolyte, the fine particles positively migrate to the anode pole,
Adheres to the oxide film being formed so that it agglomerates,
If the formation of the oxide film is further advanced in such a situation, the fine particles are taken into the oxide film, and the fine particles are partially exposed from the oxide film. In this case, it was found that the fine particles were completely taken into the oxide film. These particles are multiply laminated on the anode pole by applying a voltage during anodic oxidation,
Since it is gradually taken into the oxide film from the outermost surface of the anode electrode, regardless of the stage at which the voltage application is terminated,
Fine particles are always present on the surface of the obtained metal.

The fine particles thus obtained are incorporated into the oxide film, and the fine particles are partially exposed. The anodic oxide film having irregularities due to the fine particles has an extremely high wetting index. The reason for having such a high wetting index is that a very flat surface formed by extremely small irregularities of several nanometers to several hundreds of nanometers increases the wetting index because a substantial wetted area is increased compared to a mirror surface. Further, it is presumed that when silica or titanium oxide having a very good affinity for water is used, the wettability index is further improved because it is exposed to the oxide film surface.

The thickness of the oxide film is at least 1 nm, preferably at least 5 nm, more preferably at least 10 nm. If it is 1 nm or less, the retention of the fine particles in the oxide film is not sufficient, and the particles easily fall off. The upper limit of the thickness of the oxide film is not particularly limited, but it is sufficient to perform only the function of preventing the falling off of the fine particles. Therefore, the thickness is substantially 10 μm or less, preferably 5 μm or less, and more preferably. Is 1 μm or less. As described above, during anodic oxidation, innumerable particles deposit on the anode surface and are gradually taken into the oxide film from the outermost surface of the anode metal, so that the oxide film is thicker than the particle size of the particles. When formed, the particles existing on the outermost surface of the anode metal are completely taken in and are not exposed from the oxide film, but in this case, the particles of the second and third layers are exposed from the oxide film. There is no problem even if the fine particles contained completely cover the anodized film.

In the present invention, a metal molded article having an anodic oxide film containing fine particles is industrially manufactured by, for example, a polyamide film, a film of polyimide, polyethylene terephthalate, polyethylene naphthalate or the like. It can be used as a belt material for stable production. In addition, when other inorganic materials and organic materials are laminated and adhered on a metal material, good adhesion with the adhesive layer can be achieved by performing a treatment by an anodic oxidation method containing particles according to the method of the present invention in the case of sticking. In addition, for example, when particles such as silica are used as fine particles, it is possible to take a method of completely dissolving and removing these particles by immersing the particles in a sodium hydroxide solution or the like under heating, for example. In that case, it is possible to form an uneven anodic oxide film containing only fine holes and not containing particles.

For wear-resistant materials, pistons, rockers,
It can also be applied to parts requiring abrasion resistance, such as engine parts such as systems, equipment in hospitals, and the like. In particular, according to the present invention, the micropores and the micro uneven surface on the surface of the substrate can be formed by the anodic oxidation method, so that an applied product can be produced at low cost. Since the size, shape and concentration of the fine particles are mainly reflected in the unevenness state of the metal anodic oxide coating of the present invention, the surface state can be controlled extremely easily. In these implementations, the unevenness of the anodic oxide coating mainly reflects the size, shape and concentration of the fine particles, so that it is an extremely simple method for implementation. Hereinafter, the present invention will be described more specifically with reference to examples.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION <Method of Measuring Characteristic Value> (1) Wettability of metal molded body Measured by a method specified in JIS K6768,
The wetting index of the metal molded product was used. (2) Film Thickness of Oxide Film The film thickness was optically calculated using a multiple incidence spectral ellipsometer (VASE) manufactured by JA Woollam Company. The measurement was performed five times at different locations, and the average value was defined as the thickness of the oxide film.

(3) Observation of Surface of Oxide Film and Calculation of Ratio of Particle Surface to Oxide Film Surface A reciprocating motion was performed 1000 times in a wet state by a friction tester for a dye fastness test specified in JIS L0823. Thereafter, the minute particles that had fallen off were again washed and removed by an ultrasonic cleaner. In this way, the embedding of the fine particles into the oxide film is shallow due to the dropping process, and those that are easy to drop are dropped, and then platinum-palladium is deposited with a thickness of 2 nm,
The surface was observed at a magnification of 30,000 to 60,000 times using a Hitachi S-4700 type electron microscope. The measurement was performed five times while changing the visual field, and the average ratio of the exposed fine particles per 1 μm ² was calculated.

(4) Observation of Cross Section of Oxide Film A gold film was applied to the sample, and then a toluene solution in which polystyrene was dissolved was dropped and air-dried to form a protective film. Then, after forming a tungsten protective film on the observation site, the FB-2000 type device manufactured by Hitachi, Ltd. was used to obtain 30 × 50 μm.
was performed FIB processing performed electron beam irradiation for m ^2.
After 3 nm of Os coating was applied after the FIB processing, a cross section of the sample was observed at an inclination of 45 ° using an S-4700 type electron microscope manufactured by Hitachi, Ltd. (5) Calculation of average particle size of microparticles The electrolyte containing microparticles is diluted with distilled water to about 0.5% by weight, and this solution is placed on a grid for microscopy with a collodion film attached thereto using a nebulizer. The average particle diameter of the fine particles was calculated from 500 particle images obtained using a Hitachi H7100 transmission electron microscope (TEM).

[0033]

Example 1 A 2 × 5 cm × 1 mm mirror-polished tantalum plate was immersed in a reagent grade sulfuric acid manufactured by Wako Pure Chemical Industries for 30 minutes.
Thereafter, the sample was washed with pure water and subjected to a degreasing treatment to obtain a test piece for anodic oxidation. Colloidal silica SI-80P (40% by weight) dispersed water manufactured by Catalyst Kasei Co., Ltd. was used as an electrolytic solution. A 2 × 5 cm × 50 μm tantalum foil was used as a counter electrode, the test piece was connected using an anode of a DC power supply, and the counter electrode was connected using a cat alligator clip, and the voltage was varied under a constant current of 10 mA. Anodizing is performed at 25 ° C., and when the voltage reaches 100 V, the voltage is switched to constant voltage control of 100 V.
The operation was performed until the current reached 0 mA. Next, after washing with an ultrasonic disperser in pure water, the surface of the coating was observed. FIG. 1 shows a surface SEM photograph obtained by observing the surface of the oxide film. Wetting index and 1 square micrometer of the obtained test piece
Table 1 shows the number of particles observed in the torr and the proportion of particles exposed on the oxide film surface. The thickness of the obtained oxide film was 160 nm. The average particle diameter of the used colloidal silica SI-80P was 91 nm.
Met.

[0034]

Example 2 The same operation as in Example 1 was performed except that the current was changed to 40 mA. FIG. 2 shows the surface S obtained by observing the surface of the oxide film.
An EM photograph is shown. Table 1 shows the wetting index of the obtained test piece, the number of particles observed in one square micrometer, and the proportion of particles exposed on the oxide film surface. The thickness of the obtained oxide film was 165 nm.

[0035]

Example 3 The same procedure as in Example 1 was carried out except that the current was 150 mA. FIG. 3 shows a surface SEM photograph obtained by observing the surface of the oxide film. Table 1 shows the wetting index of the obtained test piece, the number of particles observed in one square micrometer, and the proportion of particles exposed on the oxide film surface. The thickness of the obtained oxide film was 170 nm.

[0036]

Example 4 The same operation as in Example 1 was carried out using colloidal silica MP2040 (40% by weight) manufactured by Nissan Chemical Co., Ltd. as an electrolyte. Figure 4 shows the surface SE obtained by observing the surface of the oxide film.
An M photograph is shown. Table 1 shows the wetting index of the obtained test piece, the number of particles observed in one square micrometer, and the proportion of particles exposed on the surface of the oxide film. The thickness of the obtained oxide film is as follows. 165 nm. The average particle diameter obtained by observing the particle diameter of the used colloidal silica MP2040 was 190 nm.

[0037]

Example 5 The same operation as in Example 4 was performed except that the current was 10 mA and the final voltage was 200 V. As a result, the particles appeared smaller than those observed in Example 4, and the voltage was increased by observing the particles in the second layer.
It was found that as the film thickness increased, the particles were taken into the film, the holes were closed, and the particles of the next layer were being taken into the film. FIG. 5 shows a surface SEM photograph obtained by observing the surface of the oxide film. Table 1 shows the wetting index of the obtained test piece, the number of particles observed in one square micrometer, and the proportion of particles exposed on the oxide film surface. The thickness of the obtained oxide film is 320 nm.
Met.

[0038]

Example 6 The same as Example 1 except that Nissan Chemical's Colloidal Silica MP2040 (40% by weight) was diluted with water to 4% by weight as an electrolytic solution, the current was 10 mA, and the final voltage was 100 V. It went to. FIG. 6 shows a surface SEM photograph obtained by observing the surface of the oxide film. Table 1 shows the wetting index of the obtained test piece, the number of particles observed in one square micrometer, and the proportion of particles exposed on the oxide film surface. The thickness of the obtained oxide film was 160 nm.

[0039]

Embodiment 7 The electrolytic solution was made of SI-45P manufactured by Catalyst Chemicals, Inc.
(40% by weight), anodized in the same manner as in Example 1, and ultrasonically cleaned. When the cross section of the obtained test piece was observed, it was possible to observe that colloidal silica was taken in (contained in) the anodic oxide film and was partially exposed from the film surface. FIG. 7 shows a cross-sectional SEM photograph obtained by observing the surface of the oxide film. In the figure, black particles are colloidal silica particles being taken into the oxide film, the lower part of the colloidal silica particles being about 100 nm is a tantalum oxide layer, and the lower part of the tantalum oxide layer is a tantalum plate used as a base material. A black layer of about 200 nm above the colloidal silica, and a further layer thereon are protective films made of polystyrene and tungsten provided for facilitating cross-sectional observation by SEM. The thickness of the obtained oxide film was 130 nm. Colloidal silica SI used
The average particle size obtained by observing the particle size of 45P was 43 nm.

[0040]

Comparative Example 1 The same procedure as in Example 1 was carried out except that 1N diluted sulfuric acid was used as the electrolytic solution. Since no fine particles were present in the electrolytic solution, no irregularities were formed on the surface, and the wetting index was 40 dyne / cm. The thickness of the obtained oxide film was 160 nm.

[0041]

[Table 1]

[0042]

As described above, the metal molded article of the present invention contains fine particles in the anodic oxide film, so that the film formed on the surface of the obtained metal molded article has irregularities derived from the particles. Very good wettability. Therefore, good adhesion and adhesion to a metal belt material and other materials when industrially producing a film are obtained. Further, by retaining the particles by an oxide film having a film thickness of 1/3 or more of the particle diameter of the particles, the particles can be prevented from falling off at all, and in these cases, the effect can be maintained for a long time.

[Brief description of the drawings]

FIG. 1 shows a SEM surface observation photograph obtained in Example 1.

FIG. 2 shows a surface observation photograph by SEM obtained in Example 2.

FIG. 3 shows a surface observation photograph by SEM obtained in Example 3.

FIG. 4 shows a surface observation photograph by SEM obtained in Example 4.

FIG. 5 shows a surface observation photograph by SEM obtained in Example 5.

6 shows a photograph of surface observation by SEM obtained in Example 6. FIG.

7 shows a cross-sectional observation photograph by SEM obtained in Example 7. FIG.

FIG. 8 shows the surface charge (zeta potential) and p of each particle.
The relationship of H is shown.

Claims (4)

[Claims] 1. A metal molded body having an oxide film formed on its surface by an anodization method, wherein the oxide film contains fine particles, and at least 20% of the surface of the oxide film is exposed from the oxide film. A metal molded article characterized by being occupied by fine particles. 2. The oxide film has a surface wetting index of 50 dyn.
The metal molded body according to claim 1, wherein the metal molded body is at least e / cm. 3. The metal molded product according to claim 1, wherein the oxide film has a thickness of 1 nm or more. 4. The metal compact according to claim 1, wherein the fine particles are silica, titanium oxide or alumina.