JP2014025126A - Anodic oxide film of aluminum stock and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the one having film pores with a pore diameter of 100 to 300 nm in the anodic oxide film on the surface of an aluminum stock.SOLUTION: In the method for producing an anodic oxide film, an anode 14 and a cathode 15 are immersed into an electrolyte 11 to produce an anodic oxide film on the surface of a workpiece. The production method is characterized in that, using the workpiece of an aluminum stock for the anode 14 and using a mixed solution of phosphoric acid concentration of 0.1 to 3.0 mol/L and a citric acid concentration of 0.1 to 1.5 mol/L at an electrolyte temperature of 10 to 65°C, the workpiece 14 is subjected to anode oxidation treatment under the electrolytic condition satisfying a current density of 5 to 35 A/dmto produce an anode oxide film in which the pore size of film pores is 100 to 300 nm.

Description

  The present invention relates to an anodized film having a large pore diameter of 100 nm to 300 nm applied to an aluminum material of aluminum or aluminum alloy and a method for producing the same.

  An anodized film applied to an aluminum material (aluminum base material) of aluminum or an aluminum alloy generally has a cell structure, and small pores of several tens of nanometers exist in each cell. As a method using the pores of an infinite number of anodic oxide films, it is possible to improve the lubricity by filling the hole with solid lubricant in the method of improving the integration and adhesion with resin and coating by the anchor effect. Examples thereof include a method, a method of using a noble metal in the pores as a catalyst, and a method of using an anodized film as a filter.

  When the anodized film is used for these applications, the pore diameter is preferably 100 nm or more and 200 nm or more depending on the application from the viewpoint of easy filling and loading of the substance into the film hole and prevention of clogging of the film hole.

  In anodizing treatment of an aluminum material of aluminum or aluminum alloy, a sulfuric acid bath is generally used, and an anodized film is formed on the surface thereof. However, since the pore diameter of the anodic oxide film produced in the sulfuric acid bath is about 10 nm, it is necessary to perform the step of increasing the pore diameter by immersing in an aqueous solution such as secondary electrolysis or sulfuric acid for a long time after anodizing. There is.

  The method of increasing the pore diameter of the anodized film is to increase the hole diameter by dissolving the anodized film, so there is a large variation in the hole diameter, and the solution is updated because the dissolved anodized film accumulates in the aqueous solution. There is a problem that needs to be done frequently.

  In addition, the voltage applied during the anodizing treatment and the pore diameter of the anodized film tend to be proportional, and a method for producing an anodized film having a large pore diameter using a phosphoric acid bath having a higher applied voltage than that of a sulfuric acid bath is also disclosed in Patent Literature. 1 is known, but the maximum pore diameter is 90 nm.

A method for producing a film having a large pore size using a phosphoric acid bath described in Patent Document 1 is obtained by immersing an aluminum material in an aqueous phosphoric acid solution of 1.6 to 5.0 mol / L and a liquid temperature of 10 to 30 ° C. This is used as an anode, and an anodic oxide film having a pore diameter of 30 to 90 nm is prepared by performing direct current electrolytic treatment for 5 to 25 minutes at a voltage of 20 to 100 V and a current density of 0.5 to ^{2 A} / dm ^2. This method is used for bonding.

  In this method, after an anodized film is formed on an aluminum material (aluminum base material), it is placed in a mold and the resin is injection-molded to allow the molten resin to enter the film hole, thereby joining the aluminum material and the resin.

Japanese Patent No. 4541153

  When the anodized film described in Patent Document 1 is used for various applications such as use as a catalyst by supporting a noble metal in the film hole and improvement of lubrication performance by filling with a fixed lubricant, the hole diameter of the film hole is maximum. Therefore, a method for producing an anodized film having a film hole having a larger hole diameter is desired. However, when a higher voltage is applied to obtain a film hole having a pore diameter of 100 nm or more in the anodized film using the method for producing an anodized film described in Patent Document 1, the anodized film has a problem such as film burning. It will occur. When film burning occurs, the film becomes tattered and damaged, and becomes brittle.

  The present invention has been made in consideration of the above-described circumstances, and an object thereof is to provide an anodized film having a film hole with a pore diameter of 100 nm to 300 nm on an anodized film on the surface of an aluminum material and a method for producing the same.

In order to achieve the above-described object, the present invention provides a method for producing an anodized film in which an anode and a cathode are immersed in an electrolytic solution, and an anodized film is formed on the surface of a workpiece that is the anode. Using a workpiece made of an aluminum material, a mixed solution having a phosphoric acid concentration of 0.1 to 3.0 mol / L and a citric acid concentration of 0.1 to 1.5 mol / L is added to the electrolyte at an electrolyte temperature of 10 to 65 ° C. An anodized film made of an aluminum material, characterized in that an anodized film having a pore diameter of 100 nm to 300 nm is prepared by anodizing the workpiece under electrolysis conditions with a current density of 5 to 35 A / dm ^2. A manufacturing method is provided.

  Further, in order to achieve the above-mentioned object, the present invention is provided with a workpiece made of an aluminum material on the anode, an anodized film integrally provided on the surface of the workpiece, and the anodized film has a pore diameter of 100 nm. Provided is an anodized film made of an aluminum material characterized by comprising a large number of film holes of ˜300 nm.

  Furthermore, in order to achieve the above-mentioned object, the present invention is provided with a workpiece made of an aluminum material on the anode, and the workpiece has a phosphoric acid concentration of 0.1 to 3.0 mol / L and a citric acid concentration of 0.1 to 0.1. An electrolytic solution of a 1.5 mol / L mixed solution is used at an electrolyte temperature of 10 to 65 ° C. and anodized to form an anodized film on the surface of the workpiece, and the anodized film has a thickness of 100 nm to 300 nm. An anodized film made of an aluminum material, characterized in that it is provided with a film hole having a diameter of 5 mm.

  In the present invention, an anodized film having a film hole with a pore diameter of 100 nm to 300 nm can be produced on the surface of an aluminum material, and coating adhesion can be improved by the generated anodized film. Lubricating performance can be improved by filling the holes with a lubricant.

  Moreover, since the anodic oxide film can produce a film hole having a pore diameter of 100 nm to 300 nm, it can be applied to various uses such as use as a filter by a filter or noble metal support.

The block diagram which shows the outline | summary of the anodic oxidation processing apparatus used for implementation of the anodized film of an aluminum raw material, and its manufacturing method. The table | surface data figure which shows the relationship between the hole diameter of the film hole of an anodized film, and phosphoric acid concentration. The figure which shows the graph which plotted the table data shown by FIG. The table | surface data figure which shows the relationship between the hole diameter of a film hole of an anodized film, and a citric acid density | concentration. The figure which shows the graph which plotted the table data shown by FIG. The table data figure showing the relationship between the electrolyte solution temperature comprised with a mixed solution, and the hole diameter of the film hole of an anodized film. The figure which shows the graph which plotted the table data shown by FIG. The table data figure which shows the relationship between a current density and the hole diameter of the film hole of an anodized film. The figure which shows the graph which plotted the table data shown by FIG. The table data figure which shows the relationship between the frequency change in AC / DC superposition electrolysis, and the hole diameter of the film hole of an anodized film. The figure which shows the graph which plotted the table data shown by FIG. With regard to anodized film holes produced under the electrolysis (machining) conditions of direct current electrolysis, AC / DC superposition electrolysis and alternating current electrolysis using an anodizing apparatus, the surface apparatus, hole diameter, and number of holes of the film hole are the maximum of the conventional technology. The figure shown in comparison with a hole diameter. The table data figure which shows the relationship between a current density and the hole diameter of the film hole of an anodized film. The figure which shows the graph which plotted the table data shown by FIG. The table | surface data figure which shows the relationship between processing time, the hole diameter of the film hole of an anodized film, and a film thickness.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing an outline of an anodizing treatment apparatus 10 used for carrying out an anodized film of an aluminum material (aluminum substrate) and a method for producing the same according to the present invention. The anodizing apparatus 10 includes a bathtub 12 that contains an electrolytic solution 11 that is a mixed solution of phosphoric acid and citric acid. An aluminum material (aluminum base material) serving as the anode 14 and the cathode 15 are immersed in the electrolyte solution 11 of the bathtub 12 and connected to the power source 17 via the conductive wire 16. The cathode 15 is made of a plate material such as a titanium plate, a carbon plate, an aluminum plate, or a stainless plate that is generally used in anodizing treatment. The anodizing apparatus 10 uses a power source 17 to perform any one of DC electrolysis, AC / DC superposition electrolysis, and AC electrolysis.

[Preparation method of anodized film]
For the anode 14, an aluminum material (aluminum base material) of either aluminum or an aluminum alloy is used as a workpiece. An aluminum material of aluminum or aluminum alloy is immersed in the electrolyte solution 11 of the bathtub 12, and this is used as the anode 14. The electrolytic solution is a mixed solution having a phosphoric acid concentration of 0.1 to 3.0 mol / L, a citric acid concentration of 0.1 to 1.5 mol / L, and a liquid temperature of 10 to 65 ° C.

In the anodizing apparatus 10, by applying a voltage from the power source 17 to a current density of 5 to 35 A / dm ² and performing an electrolytic processing, an anode is formed on the surface of the aluminum material 14 as an anode during the electrolytic processing. An oxide film is formed. The film hole of the anodized film becomes an anodized film having a hole diameter of 100 nm to 300 nm. The electrolytic treatment method may be any of DC electrolysis, AC / DC superposition electrolysis, or AC electrolysis, but DC electrolysis or AC / DC superposition electrolysis is preferred when it is desired to produce a film hole with a larger pore diameter. If more is required, AC electrolysis is preferred.

[Role of adding citric acid to the electrolyte]
In the invention described in Patent Document 1, anodization is performed using a single bath of phosphoric acid as an electrolytic solution. When a high voltage is applied to generate an anodized film having a large pore size, When an excessively large current flows, the anodic oxide film excessively generates heat, resulting in defects such as film burning. In the present embodiment, the phosphoric acid concentration of the electrolytic solution 11 is decreased, and citric acid having a molecular weight larger than that of phosphoric acid is added instead, and a mixed solution of citric acid and phosphoric acid is used as the electrolytic solution 11. By adding citric acid to the electrolytic solution 11, a general large current is suppressed, so that a high voltage can be applied. Even when a high voltage is applied, a large current can be prevented from flowing, and an anodized film having a large hole diameter can be produced.

[For aluminum materials]
As an aluminum material (aluminum substrate), any of aluminum alloys such as pure aluminum, A1000 series to 7000 series, AC material, ADC material, etc. may be used. In this embodiment, aluminum alloy A1100 material is used as the aluminum material. An example using is shown.

  In general, an aluminum alloy containing a large amount of alloy components such as the ADC12 material is less likely to cause a current to flow due to the influence of the alloy components, and the voltage tends to increase. As a result, as the aluminum alloy has more alloy components, the anodized film has a larger pore diameter.

  In the present embodiment, the aluminum material has a small alloy component and the current flows easily, so that the voltage is lowered, and the obtained anodic oxide film uses the aluminum alloy A1100 material in which the hole diameter of the film hole is likely to be small as a test piece. It was.

[Measurement method of pore diameter of anodized film]
The hole diameter of the anodized film produced by the anodizing apparatus 10 is determined by observing the surface of the film with a field emission scanning electron microscope, and has a plurality of film holes, for example, five hole diameters. The average value was calculated and measured.

[First embodiment]
Using the anodizing apparatus 10, an anodizing treatment was performed in which an anodized film was applied to the surface of an aluminum material (aluminum base material) as a workpiece. In the anodizing treatment, an aluminum alloy A1100 material is used as a test piece for the workpiece that is the anode 14, and the cathode 15 is typically a titanium plate, a carbon plate, an aluminum plate, or a stainless steel plate used in the anodizing treatment. An anodic oxide film was prepared using a mixed solution having a phosphoric acid concentration of 0 to 4.0 mol / L and a citric acid concentration of 0.1 to 1.0 mol / L as the electrolytic solution 11.

The electrolysis (processing) conditions of the anodizing apparatus 10 are AC / DC superimposed electrolysis (rectangular wave of voltage 0 V to maximum 300 V) of 20 kHz from the power source 17, current density 15 A / dm ² , electrolyte temperature is room temperature, for example, 20 ° C. Processing time is 1 minute.

  The test results using the anodizing apparatus 10 are shown in FIGS.

  FIG. 2 is a table data showing the relationship between the pore diameter of the prepared anodic oxide film and the phosphoric acid concentration when the citric acid concentration of the solution is constant, and FIG. 3 is a table shown in FIG. It is the graph which plotted data.

  In FIG. 3, the solid line A is a graph showing the relationship between the phosphoric acid concentration and the pore diameter of the anodized film when the citric acid concentration is 0.1 mol / L, the dotted line B and the alternate long and short dash line C are the citric acid concentration of 0.5 mol. / L and 1.0 mol / L are graphs showing the relationship between the phosphoric acid concentration and the pore diameter of the anodized film, respectively, and the reference symbol D shown by a broken line indicates the thickness of the anodized film obtained by the prior art. The line has a maximum pore diameter of 90 nm.

  When the phosphoric acid concentration of the electrolytic solution 11 was 0 mol / L, that is, in the electrolytic solution containing only citric acid, no anodized film was formed.

  When the citric acid concentration of the electrolyte solution 11 is constant at 0.1 mol / L, 0.5 mol / L, and 1.0 mol / L, the pore diameter of the coating hole increases as the phosphoric acid concentration increases from 0.1 mol / L. Increased and reached a maximum at 0.5 mol / L. When the phosphoric acid concentration exceeds 0.5 mol / L, the pore diameter of the coating pores gradually decreases. When the phosphoric acid concentration is 3.0 mol / L, the maximum pore diameter of the coating pores described in Patent Document 1 When the pore diameter is approximately the same (90 nm) and the phosphoric acid concentration is 4.0 mol / L, the pore diameter is less than the maximum pore diameter of 90 nm of the prior art disclosed in Patent Document 1.

  In the first example, from the above test results, regarding the influence of the phosphoric acid concentration, when the citric acid concentration of the electrolytic solution is substantially constant, the phosphoric acid concentration is in the range of 0.1 mol / L to 3.0 mol / L. Preferably, it is 0.3 to 1.0 mol / L. When the phosphoric acid concentration of the electrolytic solution is lower than 0.1 mol / L, the anodic oxide film is difficult to grow, and when the phosphoric acid concentration exceeds 3.0 mol / L, current flows easily. Since a large current cannot be suppressed and a high voltage cannot be applied, the hole diameter of the film hole becomes small.

  According to the first embodiment, an anodic oxide film having a large number of large-sized film holes with a pore diameter of 100 nm to 300 nm can be produced, and the generated anodized film can be used as a filter by filtering a filter or supporting a noble metal. It can be applied to many applications. In addition, since an anodized film having a film hole with a large hole diameter can be produced, the coating adhesion can be improved, and the lubricant can be effectively filled in the film hole, so that the lubrication performance is achieved. Can be improved.

[Second Embodiment]
Using the anodizing apparatus 10, a test piece of aluminum alloy A1100 material was adopted for the anode 14, which was a workpiece, and the citric acid concentration was 0 to 2.0 mol / L, and the phosphoric acid concentration was 0.1 to 3.0 mol / L. The mixed solution of L was anodized using the electrolytic solution 11 to prepare an anodized film. The other electrolysis (processing) conditions of the anodizing apparatus 10 are AC / DC superposition electrolysis (voltage: rectangular wave of 0 V to maximum 300 V) from the power source 17, current density 15 A / dm ² , electrolyte temperature is room temperature, for example, 20 ° C., treatment time 1 minute.

  The test results by the anodizing apparatus 10 are shown in FIGS. FIG. 4 is tabular data showing the relationship between the pore diameter of the prepared anodized film and the citric acid concentration when the phosphoric acid concentration of the solution is constant, and FIG. 5 is the tabular data of FIG. Is a graph in which is plotted.

  In FIG. 5, the solid line E is a graph showing the relationship between the citric acid concentration at a phosphoric acid concentration of 0.1 mol / L and the pore diameter of the anodized film. The broken line F, the alternate long and short dash line G, and the alternate long and two short dashes line H indicate the citric acid concentration and the pores of the anodized film when the phosphoric acid concentrations are 0.3 mol / L, 0.5 mol / L, and 3.0 mol / L, respectively. It is a graph which shows the relationship with a hole diameter, respectively. Reference symbol D is a broken line showing the maximum hole diameter of the film hole of the anodized film in the prior art.

  When the phosphoric acid concentration of the electrolytic solution 11 is constant at 0.1 mol / L, 0.3 mol / L, and 0.5 mol / L, respectively, the citric acid concentration is anodized as the concentration increases from 0 mol / L. The hole diameter of the film hole of the film generally increases. When the citric acid concentration was 1.5 mol / L, the pore diameter of the film pores became maximum, and at higher concentrations, the pore diameter of the film pores became substantially constant. In addition, when the phosphoric acid concentration is 3.0 mol / L, since the phosphoric acid concentration is high and current flows easily, even if citric acid is added, a temporary large current cannot be suppressed, so that the voltage that can be applied remains low. Yes, the hole diameter of the film hole was constant. Moreover, even when the citric acid concentration was 0 mol / L, it was possible to obtain pore diameters exceeding 100 nm, but there was a problem that partial film burning and fluctuations in the pore diameter of the film pores were large.

  In the second example, from the above test results, the citric acid concentration is preferably 0.1 mol / L to 1.5 mol / L when the phosphoric acid concentration of the solution is substantially constant with respect to the influence of the citric acid concentration. More preferred is 0.5 to 1.5 mol / L. When the citric acid concentration is lower than 0.1 mol / L, the effect of suppressing a temporary large current is not seen, and defects such as film burning occur. On the other hand, when the citric acid concentration exceeds 1.5 mol / L, not only the pore diameter of the film hole does not change, but also the viscosity of the electrolytic solution 11 increases and the anodizing treatment becomes difficult, which is not preferable.

  Further, in the second embodiment, it is possible to have a hole diameter equivalent to that of the anodized film shown in the first embodiment.

  Furthermore, when both the phosphoric acid concentration and the citric acid concentration are high, for example, when the phosphoric acid concentration is 1.0 mol / L and the citric acid concentration is as high as 1.0 to 1.5 mol / L, both the concentrations are each set to 0.00. It is thought that the pore diameter of the film hole is almost equal to that in the case of 5 mol / L. As the phosphoric acid concentration increases, current flows easily and the voltage that can be applied decreases. On the other hand, as the citric acid concentration increases, the temporary large current suppression effect increases and the voltage that can be applied can be increased. In the preferable concentration range of phosphoric acid concentration and citric acid concentration, when both concentrations are high, it is considered that the influence on the voltage is offset and the same pore diameter is obtained as when each concentration is 0.5 mol / L. . In general, since the applied voltage and the pore diameter are proportional, if the influence (pore diameter) of the electrolyte concentration is the same, the pore diameter will change in the same way even if other conditions such as the electrolyte temperature are changed.

[Third embodiment]
Using the anodizing apparatus 10, a test piece of aluminum alloy A1100 material is employed for the processed anode 14, and a mixed solution having a phosphoric acid concentration of 0.5 mol / L and a citric acid concentration of 0.5 mol / L is electrolyzed. An anodic oxide film was prepared by using the solution 11 while changing the electrolyte temperature to 0 to 95 ° C. In addition, the electrolysis (processing) conditions of the anodizing apparatus 10 are AC / DC superimposed electrolysis (voltage: rectangular wave of 0 V to maximum 300 V) from the power source 17, current density 15 A / dm ² , and processing time 1 minute. .

  The test results by the anodizing apparatus 10 shown in FIGS. 6 and 7 show that when the phosphoric acid concentration and citric acid concentration of the mixed solution of the electrolytic solution 11 are constant, the electrolytic solution temperature and the pore diameter of the film hole of the anodized film It shows the relationship.

  FIG. 6 is a table data showing the relationship between the electrolyte solution temperature and the pore diameter of the anodized film, and FIG. 7 is a graph plotting the table data shown in FIG. In FIG. 7, the solid line I indicates the electrolyte solution temperature and the pore diameter of the pores of the anodized film using a mixed solution in which the phosphoric acid concentration of the dissolution liquid is 0.5 mol / L and the citric acid concentration is 0.5 mol / L. It is a graph which shows the relationship. Reference sign D is a broken line indicating the maximum hole diameter of the conventional film hole, and is the same as the broken line D shown in FIGS. 3 and 5.

  When the mixed solution of the electrolytic solution 11 is made constant at a phosphoric acid concentration of 0.5 mol / L and a citric acid concentration of 0.5 mol / L, as the electrolytic solution temperature increases from 0 ° C., the anodic oxidation of the electrolytic solution 11 itself is performed. By increasing the ability to dissolve the film, the hole diameter of the film hole was increased, and was maximized when the electrolytic solution 11 was 50 ° C. When the temperature exceeds 50 ° C., the dissolving power of the electrolytic solution 11 itself becomes excessively high, and it becomes impossible to apply a high voltage because the current easily flows due to the increase of the electrolytic power, and the hole diameter of the film hole becomes small. Further, when the electrolytic solution 11 was lower than 10 ° C., the anodized film was difficult to grow, and when it exceeded 65 ° C., the water in the electrolytic solution was easily evaporated.

  In the third example, from the above test results, regarding the influence of the electrolyte temperature on the pore diameter of the coating hole, the electrolyte temperature is preferably 10 to 65 ° C, more preferably 10 to 50 ° C. When the electrolyte temperature is lower than 10 ° C., not only is the anodic oxide film difficult to grow, but a cooler having a high cooling capacity is required, which consumes a large amount of energy, which is not preferable. It can be found that when the electrolytic solution temperature exceeds 65 ° C., the water in the electrolytic solution 11 easily evaporates, which makes it difficult to manage the electrolytic solution concentration.

  Also in the third embodiment, an anodized film having a film hole having a large pore diameter of 120 nm or more can be provided as compared with the film hole having the maximum pore diameter of the prior art anodized film.

[Fourth embodiment]
Using the anodizing apparatus 10, a test piece of aluminum alloy A1100 material is employed for the processed anode 14, and a mixed solution having a phosphoric acid concentration of 0.5 mol / L and a citric acid concentration of 0.5 mol / L is electrolyzed. An anodic oxide film was prepared using the liquid 11 while changing the current density from 0.1 to 45 A / dm ² as the electrolytic (processing) condition from the power source 17. Other electrolysis conditions of the anodizing apparatus 10 are 20 kHz AC / DC superposition electrolysis (voltage: rectangular wave of 0 V to maximum 300 V) or DC electrolysis, and the electrolyte temperature is room temperature, for example, 20 ° C., and the treatment time is 1 minute.

  The test results by the anodizing apparatus 10 shown in FIG. 8 and FIG. 9 show that when the mixed solution of the electrolytic solution 11 is constant at a phosphoric acid concentration of 0.5 mol / L and a citric acid concentration of 0.5 mol / L, electrolysis (processing) ) The relationship between the current density of the conditions and the hole diameter of the film hole of the anodized film is shown.

  Among these, FIG. 8 is a table data showing the relationship between the current density and the pore diameter of the anodized film, and FIG. 9 is a graph plotting the table data shown in FIG. In FIG. 9, the solid line J shows the current density and anodic oxidation under electrolytic (processing) conditions using a mixed solution in which the phosphoric acid concentration of the electrolytic solution 11 is 0.5 mol / L and the citric acid concentration is 0.5 mol / L. It is a graph which shows the relationship with the hole diameter of the film hole of a film | membrane.

When the mixed solution of the electrolytic solution 11 has a constant phosphoric acid concentration of 0.5 mol / L and a citric acid concentration of 0.5 mol / L, the pore diameter of the pores of the anodized film increases as the current density increases. Is 35 A / dm ² or more, the hole diameter of the film hole is constant. Since the current density is proportional to the applied voltage, the higher the applied voltage, the larger the hole diameter of the film hole. In addition, there was no difference in the hole diameter of the anodized film due to the difference between AC / DC superposition electrolysis, direct current electrolysis and electrolysis (processing) conditions.

In the fourth example, from the above test results, the current density is preferably 5 to 35 A / dm ² with respect to the influence of the current density. More preferably from 10~25A / dm ^2. When the current density is lower than 5 A / dm ² , the applied voltage is also reduced, so that the hole diameter of the coating hole is reduced. When the current density exceeds 35 A / dm ² , heat generation is locally increased, and cooling cannot catch up only with stirring of the electrolytic solution, and the anodized film suffers from defects such as film burning.

  In the fourth embodiment, it is possible to provide an anodized film having a film hole having a maximum hole diameter of 90 nm or more and a hole diameter of 300 nm in the prior art.

[Fifth embodiment]
Using the anodizing apparatus 10, a test piece of aluminum alloy A1100 material was adopted for the anode 14 as a workpiece, and the electrolyte solution 11 had a phosphoric acid concentration of 0.5 mol / L and a citric acid concentration of 0.5 mol / L. Using the mixed solution, the anodizing film is produced by changing the frequency in the AC / DC superposition electrolysis in the range of 50 to 20000 Hz (voltage: rectangular wave of 0V to maximum 300V) according to the electrolysis (processing) conditions of the anodizing apparatus 10. went. Other electrolysis conditions are a current density of 15 A / dm ² , an electrolyte temperature of room temperature, for example, 20 ° C., and a processing time of 1 minute.

  The test results obtained by the anodizing apparatus 10 are shown in FIGS. Among these, FIG. 10 shows the frequency change in AC / DC superposition electrolysis and the anodized film when the density of the mixed solution of the electrolytic solution 11 is constant at a phosphoric acid concentration of 0.5 mol / L and a citric acid concentration of 0.5 mol / L. 11 is a graph plotting the table data shown in FIG. 10. In FIG. 11, the solid line L indicates that the pore diameter of the anodized film is constant even when the frequency is changed.

  Therefore, in the fifth example, it has been found that even if the frequency in AC / DC superposition electrolysis is changed, the hole diameter of the film hole is substantially constant and does not change, so the change in frequency does not affect the size of the hole diameter of the film hole. However, the higher the frequency, the shorter the time during which a high voltage is applied in one cycle, the less heat generation, the smaller the temperature change of the electrolyte solution 11, and the more effective for mass production.

[Sixth embodiment]
Using the anodizing apparatus 10, a test piece of aluminum alloy A1100 material was adopted for the anode 14, which was a workpiece, and the electrolyte solution 11 had a phosphoric acid concentration of 0.5 mol / L and a citric acid concentration of 0.5 mol / L. Using the mixed solution, an anodized film was prepared by using direct current electrolysis, AC / DC superposition electrolysis, and alternating current electrolysis for the anodizing apparatus 10. In addition, the electrolysis (processing) conditions of the anodizing apparatus 10 include a frequency of 20 kHz (voltage of AC / DC superposition electrolysis: rectangular wave of 0 V to maximum 300 V, voltage of AC electrolysis: sin wave of maximum ± 300 V), current density 15 A / dm. ^2. Electrolyte temperature is normal temperature, for example, 20 degreeC, and processing time is 1 minute.

  The anodic oxidation processing apparatus 10 used in the sixth embodiment can perform any electrolytic processing such as direct current electrolysis, AC / DC superposition electrolysis, or alternating current electrolysis, and may be any power source 17 that can perform any electrolytic processing. It is not limited to a specific power source 17.

  When an anodic oxide film is produced using the anodic oxidation treatment apparatus 10 of direct current electrolysis and AC / DC superposition electrolysis, as shown in FIG. 12, the average pore diameters of the film holes are 236 nm and 215 nm, which are 200 nm or more respectively. The pore diameter was obtained.

  Further, as shown in FIG. 12, when an anodized film is produced using an anodizing apparatus 10 for AC electrolysis, the hole diameter of the film hole formed in the anodized film is the same as that of the anodized film shown in the comparative example. Although it was larger than the maximum hole diameter (90 nm) of the film hole, for example, an average of 115 nm, it was smaller than the hole diameter of DC electrolysis or AC / DC superposition electrolysis. The AC electrolysis is characterized in that the number of pores of the anodized film is larger than that of DC electrolysis or AC / DC superposition electrolysis.

  In the sixth embodiment, an anodic oxide film having a larger hole diameter than that of the prior art can be produced by using any one of DC electrolysis, AC / DC superposition electrolysis, and AC electrolysis for the anodizing apparatus 10. It was found that DC electrolysis and AC / DC superposition electrolysis are preferable when importance is attached to the pore size of the coating hole, and AC electrolysis is preferred when importance is attached to the number of pores of the coating hole.

  In the anodic oxide films produced in the first to sixth examples, anodization having a large number of large pore diameters, for example, 100 nm to 300 nm, exceeding the maximum pore diameter of the anodized film obtained by the prior art. A film can be produced.

  When the anodized film has a film hole having a large pore diameter of 100 nm to 300 nm, coating adhesion is improved, and a filtration filter resistant to strong acids and organic solvents can be obtained. In addition, since an anodic oxide film having a film hole with a large pore diameter can be provided, oil retention can be improved and a solid lubricant can be filled in the film hole, thereby improving lubricity. Furthermore, by supporting a noble metal such as platinum in a film hole having a large pore diameter of the anodized film and using it as a catalyst, the surface area of the catalyst is improved and the catalyst function can be effectively exhibited.

  In addition, the anodic oxide film can easily enter the electrolyte solution deeply into the large pore film hole, and the anodic oxide film can be thickened.

[Seventh embodiment]
In the first to sixth embodiments, an example in which an anodized film was produced on an aluminum alloy by the anodizing apparatus 10 using the aluminum alloy A1100 material as a test piece was shown. However, other aluminum alloys (AC material and ADC) Material) may be used to produce an anodized film.

  FIG. 13 and FIG. 14 compare an example in which an anodized film was produced by the anodizing apparatus 10 using an aluminum alloy A5052 material as a test piece and an example produced using a test piece of an aluminum alloy A1100 material. It is shown.

The anodized film was prepared under the conditions of AC / DC superimposed electrolysis conditions in which the phosphoric acid concentration and citric acid concentration were both 0.5 mol / L, the electrolyte temperature was 20 ° C., and 20 kHz, and the current density was changed by 5 to 45 A / dm ^2. Thus, an anodized film was prepared.

  FIG. 13 is a table data showing the relationship between the current density and the pore diameter of the anodized film, and FIG. 14 is a graph plotting the table data shown in FIG. As shown in FIG. 14, there was no significant difference in the hole diameter of the anodized film between the aluminum alloy A5052 material indicated by the solid line M and the aluminum alloy A1100 material indicated by the dotted line N. In other words, it was found that even if the material of the aluminum alloy is different, the film holes of the anodized film are substantially the same without any significant change in the hole diameter. For other aluminum alloys such as AC materials and ADC materials, the change in the hole diameter of the anodized film is considered to be substantially the same.

[Other embodiments]
In the first to sixth examples, an example in which an anodized film was formed on an aluminum alloy A1100 material using a anodizing apparatus 10 in a processing time of 1 minute has been described. The effect of the treatment time on the preparation of the anodized film was investigated.

  FIG. 15 is table data showing the influence of the hole diameter and film thickness of the film hole of the anodized film produced by extending the treatment time to 3 minutes. According to the test results shown in FIG. 15, it was found that the film thickness of the anodized film was increased by extending the treatment time, but it was found that no change in the hole diameter of the film hole occurred. Moreover, when the film thickness of the anodized film is about 1 to 2 μm, it is difficult to use for various applications, and when the film thickness is less than 3 μm, the application is limited.

10 Anodizing treatment device 11 Electrolytic solution (mixed solution of phosphoric acid and citric acid)
12 Bath 14 Anode (aluminum material, aluminum base)
15 Cathode 16 Conductive wire 17 Power supply

Claims (11)

In the method for producing an anodic oxide film in which an anode and a cathode are immersed in an electrolytic solution, and an anodic oxide film is generated on the surface of the workpiece as the anode,
Using a workpiece made of an aluminum material for the anode, a mixed solution having a phosphoric acid concentration of 0.1 to 3.0 mol / L and a citric acid concentration of 0.1 to 1.5 mol / L is added to the electrolyte solution. Use at 65 ° C,
A method for producing an anodized film of an aluminum material, characterized in that the workpiece is anodized under electrolysis conditions of a current density of 5 to 35 A / dm ² to produce an anodized film having a pore diameter of 100 nm to 300 nm. . The anode of an aluminum material according to claim 1, wherein the electrolytic solution is preferably a mixed solution having a phosphoric acid concentration of 0.3 to 1.0 mol / L and a citric acid concentration of 0.5 to 1.5 mol / L. Manufacturing method of oxide film. ^2. The method for producing an anodized film of an aluminum material according to claim 1, wherein the workpiece is preferably anodized under electrolysis conditions of a current density of 10 to 25 A / dm ² . The method for producing an anodized film of an aluminum material according to claim 1, wherein the electrolytic solution is preferably used at a temperature of 10 to 50 ° C. 2. The method for producing an anodized film of an aluminum material according to claim 1, wherein the workpiece is anodized under an electrolytic condition of DC electrolysis, AC / DC superposition electrolysis or AC electrolysis. 2. The method for producing an anodized film of an aluminum material according to claim 1, wherein when the pore size of the film of the anodized film is important, anodization is performed by direct current electrolysis or AC / DC weight electrolysis. The method for producing an anodized film of an aluminum material according to claim 1, wherein when the number of holes is important in the film hole of the anodized film, anodization is performed by AC electrolysis. 2. The anodization of an aluminum material according to claim 1, wherein when the workpiece is anodized under an electrolytic condition of AC / DC weight electrolysis with a frequency of 50 to 20000 Hz, the higher frequency is selected and the anodization is performed. A method for producing a film. An aluminum workpiece is provided on the anode,
Anodized film is integrally provided by anodizing treatment on the surface of the workpiece,
The anodized film made of an aluminum material, wherein the anodized film has a large number of film holes having a pore diameter of 100 nm to 300 nm. An aluminum workpiece is provided on the anode,
An electrolytic solution of a mixed solution having a phosphoric acid concentration of 0.1 to 3.0 mol / L and a citric acid concentration of 0.1 to 1.5 mol / L is used for the workpiece at an electrolyte temperature of 10 to 65 ° C. An anodized film is formed on the surface of the workpiece,
The anodized film of aluminum material, wherein the anodized film is provided with a film hole having a pore diameter of 100 nm to 300 nm. 11. The anodization of an aluminum material according to claim 10, wherein an electrolytic solution of a mixed solution having a phosphoric acid concentration of 0.3 to 1.0 mol / L and a citric acid concentration of 0.5 to 1.5 mol / L is used for the workpiece. Film.