KR20180131278A - Aluminum member with protective film on its surface and method for fabricating the same - Google Patents

Abstract

Disclosed is a method for manufacturing an aluminum member having a base material made of a bare aluminum alloy and a protective coating laminated on a surface of the base material. The disclosed protective coating of the aluminum member includes a nonporous anodic oxide layer having: porous aluminum oxide on which a plurality of pores are formed and which is laminated on the surface of the base material; a porous anodic oxide layer having a thickness of 1 to 7 μm, and a porous layer formed on an inner peripheral surface of the plurality of pores and a partition wall between the plurality of pores; and a nonporous anodic oxide layer made of a nonporous aluminum oxide having a thickness of 200 to 700 nm. An entrance of a plurality of pores are not closed by the nonporous anodic oxide layer.

Description

Technical Field [0001] The present invention relates to an aluminum member having a protective coating and an aluminum member with a protective film on its surface and method for fabricating the same,

The present invention relates to an aluminum member having a protective coating on its surface so as to improve the corrosion resistance of the aluminum surface.

For example, a deposition chamber is used for a deposition process for manufacturing a semiconductor chip or the like. In the deposition chamber, an aluminum (Al) material such as a diffuser, a shower head, and an upper electrode used for spraying a deposition material is provided.

An aluminum or aluminum alloy material is formed by laminating an anodized film on its surface to improve the corrosion resistance of the surface. A typical method is a porous anodizing method in which electrolysis is performed using an aluminum material as an anode in an acidic electrolytic solution. An anodic oxide film formed on the surface of the aluminum material through the electrolytic solution has a large number of fine pores a pore may be formed and a hydration sealing process may be added to close the plurality of fine pores.

A part made of an aluminum material having an anodic oxidation coating formed through hydration and pore processing after the porous anodizing treatment is exposed to a severe deposition environment of high vacuum or high temperature inside the deposition chamber. Cracks are generated in the anodic oxide coating of the aluminum component in a high temperature deposition environment of 250 to 500 ° C in the deposition chamber, thereby increasing the impurity particles in the deposition chamber.

In order to prevent this, it is possible to apply an aluminum component which is not subjected to hydration-piercing after the porous anodizing treatment, but in this case, the reactivity becomes large due to a large number of micropores on the surface of the aluminum member, which adversely affects the deposition rate, The performance of the resulting film may be degraded.

On the other hand, a part made of a so-called bare aluminum material which does not have an anodized film on its surface may be used in the inside of the deposition chamber. However, in this case it is generated aluminum fluoride (AlF _N) to the surface of the bare aluminum components in the process of cleaning the deposition chamber using a periodically nitrogen trifluoride (NF ₃₎ and nitrogen tetrafluoride (CF _4). The aluminum fluoride (AlF 2 _{N 4} ) is detached from the surface of the bare aluminum part in a subsequent deposition process, thereby increasing the amount of impurity particles in the deposition chamber and degrading the quality of the deposition. Therefore, the replacing cycle of the bare aluminum part is shortened, and the cost of the deposition work is increased.

Korean Patent Publication No. 10-2004-0077949

The present invention relates to an aluminum member having a protective coating for suppressing surface damage such as surface corrosion, surface cracking and particle separation on the surface even in a severe working environment such as high temperature, high vacuum and strong acid exposure, And a manufacturing method thereof.

The present invention relates to a base material comprising a base material made of a bare aluminum alloy and a protective film laminated on the surface of the base material, wherein the protective film is laminated on the surface of the base material, A porous anodic oxide layer having a thickness of 1 to 7 탆 and formed of porous aluminum oxide on which pores of pores are formed and a porous anodic oxidation layer formed on the inner peripheral surface of the plurality of pores and the partition wall between the plurality of pores, And a non-porous anodization layer made of non-porous aluminum oxide and having a thickness of 200 to 700 nm, wherein an opening of the plurality of pores is not closed by the non-porous anodization layer, to provide.

The porous anodization layer may not include a salt formed by reacting aluminum (Al) with an acid and a hydrate combined with moisture (H ₂ O).

The present invention also provides a method for producing an aluminum member having a protective coating on its surface, comprising the steps of: forming a porous (porous) member having a plurality of pores formed on a surface of a base material made of a bare aluminum alloy; A porous anodic oxidation layer stacked on the porous anodization layer, the porous anodization layer being made of aluminum oxide and having a thickness of 1 to 7 mu m; a porous anodization layer etching step of etching the porous anodization layer so as to enlarge an inner diameter of the plurality of pores; And an airless layer which is made of nonporous aluminum oxide and has a thickness of 200 to 700 nm and is laminated on the inner circumferential surface of the plurality of pores having the expanded inner diameter and the partition wall between the plurality of pores And an anodization layer stacking step, wherein the inlet of the plurality of pores may not be closed by the nonporous anodization layer.

Wherein the porous anodization layer stacking step includes an acid electrolytic solution electrolysis step of immersing the base material in an acidic electrolyte and electrolyzing the base material as an anode, A neutral electrolytic solution electrolysis step of immersing the base material in which the anodic oxidation layer is laminated in a neutral electrolyte and electrolyzing the base material as an anode.

Wherein the acidic electrolytic solution is an aqueous solution of sulfuric acid (H ₂ SO ₄ ), and the salt (Al ₂ (SO ₄ ) ₃ ) formed by reacting aluminum (Al) _{2 O) (Al 2 (SO} 4) the combined luggage _3? nH ₂ O, n is a natural number) is deposited on the inner circumferential surface of the plurality of pores, the hydrate in the porous anodized layer etching step (Al ₂ (SO ₄ ) ₃ ? NH ₂ O) can be removed from the porous anodization layer.

(Al ₂ (C ₂ O ₄ ) ₃ ) formed by reacting aluminum (Al) of the base material with the acid in the electrolytic step of the acidic electrolytic solution, wherein the acidic electrolytic solution is an aqueous solution of H ₂ C ₂ O ₄ , and water (H ₂ O) is bonded hydrate _{(Al 2 (C 2 O 4} ) 3? nH 2 O, n is a natural number) is deposited on the inner circumferential surface of the plurality of pores, the hydrate in the porous anodized layer etching step (Al ₂ (C ₂ O ₄ ) ₃ ? NH ₂ O) may be removed from the porous anodization layer.

The method of manufacturing an aluminum member having a protective coating according to the present invention is characterized in that after the step of laminating the porous anodic oxide layer, the porous anodic oxide layer and the porous anodic oxide layer are laminated in a vacuum environment or an atmosphere filled with nitrogen gas, And a heat treatment step for performing heat treatment.

In the porous anodization layer etching step, an aqueous solution of phosphoric acid (H ₃ PO ₄ ) may be introduced into the porous anodization layer as an etching agent.

The porous anodization layer etching step may include the step of injecting the aqueous phosphoric acid solution into the porous anodization layer at a concentration of 3 to 20 wt% and a temperature of 50 to 100 DEG C for 1 to 10 minutes.

The aluminum member of the present invention has a protective coating with a porous anodization layer made of porous aluminum oxide and a nonporous anodization layer made of nonporous aluminum oxide. The nonporous anodization layer is a so-called barrier type anodization layer, which is thinner than the porous anodization layer and is dense in texture. The nonporous anodization layer is laminated so as to surround the porous anodization layer, And has characteristics similar to those in which the nonporous anodic oxide layer is thickly laminated. Therefore, surface damage such as surface corrosion, surface cracking, and particle separation on the surface of an aluminum member is suppressed even in a severe working environment such as high temperature, high vacuum, and strong acid exposure.

Particularly, even in the case of an aluminum member having a plurality of holes having an inner diameter of 0.1 to 1 mm such as a diffuser or a shower head installed in a deposition chamber, the porous anodic oxide layer and the non- The surface damage on the inner circumferential surface of the hole is suppressed in a severe working environment. In addition, even when the reclaimed work of peeling off the damaged film on the surface of the aluminum member and using the protective film again after long use is performed, the inner diameter of the hole is not excessively expanded so that the number of recycling operations is increased Resources are saved, and durability is improved.

In the aluminum member manufactured according to the preferred embodiment of the present invention, the porous anodization layer is etched, so that the hydrate combined with the salt and water is removed in the porous anodization layer, thereby lowering the moisture content of the protective coating. Therefore, even when the aluminum member is used in the deposition chamber, the generation of cracks on the surface of the aluminum member and the generation of particles in the deposition chamber are suppressed, and the material of the film formed by the operation in the deposition chamber is improved .

In addition, the aluminum member having the protective coating manufactured according to the preferred embodiment of the present invention in which heat treatment is added after the nonporous anodization layer is laminated is characterized in that the moisture contained in the nonporous anodization layer is removed and the density of the material is increased The corrosion resistance of the nonporous anodic oxidation layer is further improved and surface damage such as surface corrosion of the aluminum member, surface cracking, particle separation at the surface, and the like is further suppressed even in a severe working environment such as in a vacuum chamber.

1 to 4 are sectional views sequentially illustrating a method of manufacturing an aluminum member according to an embodiment of the present invention.

Hereinafter, an aluminum member having a protective coating and a method of manufacturing the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. The terminology used herein is a term used to properly express the preferred embodiment of the present invention, which may vary depending on the intention of the user or operator or the custom in the field to which the present invention belongs. Therefore, the definitions of these terms should be based on the contents throughout this specification.

1 to 4 are sectional views sequentially illustrating a method of manufacturing an aluminum member according to an embodiment of the present invention. The aluminum member manufacturing method of the present invention includes a base material preparation step (S10), a porous anodization layer deposition step (S20), a porous anodization layer etching step (S30), and an anodic anodization layer deposition step (S40). Referring to FIG. 1, a base material preparing step S10 is a step of preparing a base material 11 made of a bare aluminum alloy.

The aluminum alloy includes aluminum (Al) as a main material and contains a small amount of another material. The small amount of the other material is selected from the group consisting of iron (Fe), copper (Cu), manganese (Mn) Magnesium (Mg), and zinc (Zn). Aluminum alloys are more suitable for use in harsh environments in a deposition chamber because they have excellent physical properties such as strength, for example, compared to 100% pure aluminum. The base material 11 is a bare metal in which an aluminum oxide (Al ₂ O ₃ ) coating is not formed on the surface.

Specifically, the base material preparation step S10 includes a shape processing step of machining a plate or ingot made of an aluminum alloy into a shape of a specific aluminum member, a heat treatment step of heat-treating the shape-processed base material, A chemical cleaning step of chemically cleaning the surface of the base material by using a cleaning agent, and a polishing step of polishing the surface of the base material. The shaping step includes forming a plurality of holes 15 penetrating the base material 11 in the thickness direction and having an inner diameter (HD) of 0.1 to 1 mm. The aluminum member 10 (see FIG. 3) having the plurality of holes 15 may be, for example, a diffuser in a deposition chamber, or a shower head. The chemical cleaning step and the polishing step are examples of a method for forming a bare-shaped base material 11 in which a film made of aluminum oxide (Al ₂ O ₃ ) is not laminated on the surface.

2, a porous anodized layer lamination step (S20) is the surface of the base material 11 made of the bare aluminum alloy, a large number of pores (pore) (26) is porous (多孔質) aluminum oxide is formed of (Al ₂ O ₃ ) and having a thickness (OT1) of 1 to 7 μm is laminated on the porous anodization layer 20. The porous anodization layer stacking step S20 includes an acid electrolytic solution electrolysis step of immersing the base material 11 in an acidic electrolyte and electrolyzing the base material 11 as an anode. The porous anodization layer 20 is also formed on the inner peripheral surface of the hole 15 of the base material 11 having an inner diameter (HD) of 0.1 to 1 mm.

As the pretreatment step preceding the electrolytic step of the acid electrolytic solution, a degreasing step, a cleaning step, and a neutralization step may be provided. The degreasing step is a step of removing oil from the surface of the base material 11, and the cleaning step is a step of removing aluminum oxide and foreign matter from the surface of the base material 11 by immersing in an acidic or basic aqueous solution, The acid or base remaining on the surface of the base material 11 is neutralized.

The acidic electrolytic solution may be, for example, an aqueous solution of sulfuric acid (H ₂ SO ₄ ) or an aqueous solution of hydrous acid (H ₂ C ₂ O ₄ ). The acid electrolytic solution electrolysis step is continued until the thickness OT1 of the porous anodization layer 20 grows to 1 to 7 mu m. Although the thickness OT1 of the porous anodization layer 20 becomes thicker as the electrolysis time becomes longer, the structure becomes fragile and fragile, and since the homogeneous porous anodization layer 20 is not formed, It is not desirable to last too long.

The plurality of pores 26 extend in the thickness OT1 direction of the porous anodic oxide layer 20 and are spaced apart from each other. The inlet of the plurality of pores 26 is provided on the surface of the porous anodization layer 20. The inner diameter PD1 of the pores 26 may be approximately 30 to 50 nm. The depth of the pores 26 is smaller than the thickness OT1 of the porous anodization layer 20 because the pores 26 do not extend beyond the porous anodization layer 20 to the base material 11. [ The thickness WT1 of the partition wall between the pair of pores 26 adjacent to each other in the porous anodization layer 20 may be approximately 80 to 110 nm. However, PD1 and WT1 are merely examples.

In the acid electrolytic solution electrolysis step, the aluminum (Al) component reacts with the acidic electrolyte to form a salt, and the hydrate (22) formed by reacting the salt with the water (H ₂ O) ) And the pores (26). For example, if the acidic electrolytic solution of sulfuric acid (H ₂ SO ₄₎ in the case of aqueous solutions, the salt formed by the aluminum and the sulfuric acid reaction in the acidic electrolyte electrolysis step _{(Al 2 (SO 4) 3} ) and water (H ₂ O) -based hydrate (Al ₂ (SO ₄ ) ₃ ? NH ₂ O, n being a natural number) is deposited on the inner peripheral surface of the plurality of pores 26 and the partition wall between the adjacent pores 26. As another example, when the acidic electrolytic solution is an aqueous solution of H ₂ C ₂ O ₄ , a salt (Al ₂ (C ₂ O ₄ ) ₃ ) formed by reacting aluminum with the acid in the electrolysis step (H ₂ O) -based hydrate (Al ₂ (C ₂ O ₄ ) ₃ ? NH ₂ O, where n is a natural number) is deposited on the inner peripheral surface of the plurality of pores 26 and the partition wall between the adjacent pores 26 do.

Referring to FIG. 3, the porous anodization layer etching step S30 is a step of etching the porous anodization layer 20 so that the inner diameter PD2 of the plurality of pores 26 is expanded. The porous anodization layer etching step (S30) includes a step of applying an etching agent to the porous anodization layer (20). Comparing the pores 26 in Fig. 2 and Fig. 3 and the partition walls between the adjacent pores 26, the inner diameter of the pores 26 increases from PD1 to PD2 through step S30, Is thinned from WT1 to WT2. The etchant of the porous anodization layer 20 proceeds on the inner circumferential surface of the hole 15 because the etchant also flows into the hole 15 formed in the base material 11 having an inner diameter (HD) of 0.1 to 1 mm.

For example, after step S30, the inner diameter PD2 of the pores 26 is 70 to 90 nm, and the thickness WT2 of the partition wall is approximately 40 to 70 nm. Since the etching solution is isotropically etched in the pores 26, the etching rate of the bottom of the porous anodization layer 20 and the end of the porous anodization layer 20 is substantially equal to the etching rate of the bottom of the pores 26. That is, since the bottom surface of the pore 26 is also etched as the end of the barrier is etched, the depth of the pore 26 before and after the step S30 is substantially constant without change. Since the ends of the barrier ribs are etched in step S30, the thickness OT2 of the porous anodization layer 20 is slightly smaller than the thickness OT1 before the step S30.

The etching solution may be a phosphoric acid (H ₃ PO ₄₎ solution. As a specific example, an aqueous phosphoric acid solution having a concentration of 3 to 20 wt% and a temperature of 50 to 100 DEG C is charged into the porous anodization layer 20 for 1 to 10 minutes so that the inner diameter PD2 of the plurality of pores 26 is expanded The porous anodization layer 20 can be etched. In addition, the porous anodization layer etching step S30 may be performed by immersing the base material 11 having the porous anodization layer 20 formed thereon in the aqueous phosphoric acid solution.

In the porous anodization layer etching step S30, the hydrate 22 (see FIG. 2) which has been laminated on the inner peripheral surface of the plurality of pores 26 by the etching solution is etched and removed from the porous anodization layer 20, (Al ₂ O ₃ ) constituting the honeycomb structure 20 is exposed on the inner peripheral surface of the pores 26. As described above in the porous anodizing step S20, the hydrate 22 to be removed can be formed by, for example, a method in which a salt (Al ₂ (SO ₄ ) ₃ ) formed by the reaction of aluminum and sulfuric acid is mixed with water (H ₂ O) hydrate _{(Al 2 (SO 4) 3} ? nH 2 O, n is a natural number), or aluminum and salts formed with hydroxyl the reaction _{(Al 2 (C 2 O 4} ) 3) and water (H ₂ O) is bonded hydrate (Al ₂ (C ₂ O ₄ ) ₃ ? NH ₂ O, n is a natural number).

4, the nonporous anodizing layer stacking step S40 includes a step of forming a porous layer on the inner circumferential surface of the plurality of pores 26 having the inner diameter PD2 (see FIG. 3) extended and the partition wall between the plurality of pores 26, And an unpurified anodic oxidation layer 30 made of nonporous aluminum oxide and having a thickness (AT) of 200 to 700 nm. The nonporous anodization layer stacking step S40 includes a neutral electrolytic solution electrolysis step and is a pretreatment step prior to the neutral electrolytic solution electrolysis step. The porous anodization layer step S30 is performed on the surface of the porous anodization layer 20 And a neutralizing step of neutralizing the remaining etching solution.

In the neutral electrolytic solution electrolysis step, the base material 11 in which the porous anodization layer 20 is laminated is immersed in a neutral electrolyte, and electrolysis is performed using the base material 11 as an anode . The neutral electrolyte is, for example, an aqueous solution of a neutral electrolyte such as boric acid, borate, phosphate, or adipate. A plurality of kinds of neutral electrolytes may be included in the neutral electrolyte.

For example, the concentration of the neutral electrolyte contained in the neutral electrolytic solution may be 1 to 200 g / l. The temperature of the neutral electrolyte may be from 50 to 90 캜. The voltage between the anode electrode and the cathode electrode may be DC 30 to 50 V. The electrolysis time depends on the thickness (AT) of the nonporous anodization layer 30, and may be within 1 minute or less than 30 minutes have.

The neutral electrolyte electrolysis may also be referred to as barrier type anodizing. The nonporous anodization layer 30 formed through the electrolysis of the neutral electrolyte has a surface with no pores and a thickness (AT) as thin as several tens to several hundred nanometers (nm) The porous anodization layer 20 is excellent in corrosion resistance to withstand a harsh environment than the porous anodization layer 20. The neutral electrolyte flows into the hole 15 formed in the base material 11 with the inner diameter HD of 0.1 to 1 mm so that the nonporous anodization layer 30 is also laminated on the inner peripheral surface of the hole 15.

3 and 4, since the nonporous anodization layer 30 is laminated on the inner peripheral surface of the plurality of pores 26 and the partition wall between the plurality of pores 26, the inner diameter PD3 of the pores 26 is Becomes smaller than the inner diameter PD2 of the pores 26 after the porous anodization layer etching step S30 and the thickness WT3 of the partition walls becomes thicker than the thickness WT2 of the partition walls after the porous anodization layer etching step S30. Since the nonporous anodization layer 30 is laminated on the surface of the porous anodization layer 20, the total thickness OT3 of the anodization layer is determined by the thickness OT2 of the porous anodization layer 20 after the porous anodization layer etching step S30 (See Fig. 3).

The method for manufacturing an aluminum member of the present invention is characterized in that the porous anodization layer 20 and the nonporous anodization layer 30 are laminated in a vacuum environment or an atmosphere filled with nitrogen gas after the step of laminating the non- And a heat treatment step of subjecting the base material 11 to a heat treatment. Specifically, the base material 11, on which the porous anodization layer 20 and the non-porous anodization layer 30 are laminated, may be left at 200 to 500 ° C for heat treatment. The heat treatment time can be shortened with higher temperature. As another example of the heat treatment step, RTA (Rapid Thermal Annealing) in which the base material 11 in which the porous anodization layer 20 and the nonporous anodization layer 30 are laminated is left at a high temperature higher than 500 캜 for a time of 30 seconds or less ) Can be applied. When the base material 11 is left at a high temperature for a long time in the case of heat treatment at a temperature higher than 500 ° C, the base material 11 made of a bare aluminum alloy may be deformed. . Since the moisture contained in the nonporous anodization layer 30 is removed and the density of the material is increased through the heat treatment step, the corrosion resistance of the nonporous anodization layer 30 is further improved.

The aluminum member 10 of the present invention shown in Fig. 4 is superior in durability in a harsh environment than the base material 11 made of pure aluminum, in which the base material 11 is made of an aluminum alloy. The aluminum member 10 includes a porous anodization layer 20 made of porous aluminum oxide and a non-porous anodization layer 30 made of non-porous aluminum oxide, Respectively. The porous anodization layer 30 is thinner than the porous anodization layer 20 and has a dense structure. Since the porous anodization layer 30 is laminated so as to surround the porous anodization layer 20, The porous anodization layer 30 has properties similar to those of the porous anodization layer 20 thickly laminated. Therefore, surface damage such as surface corrosion, surface cracking, particle separation on the surface, etc. of the aluminum member 10 is suppressed even in a severe working environment such as high temperature, high vacuum, and strong acid exposure.

Particularly, when a plurality of holes 15 having an inner diameter (HD) of 0.1 to 1 mm are formed in the aluminum member 10 such as a diffuser or a shower head installed in the deposition chamber, the porous anodic oxidation layer (20) and the nonporous anodization layer (30) are laminated together as two layers, the surface damage on the inner peripheral surface side of the hole (15) is suppressed in a severe working environment. Further, even if recycling operation is performed in which the damaged film on the surface of the aluminum member 10 is peeled off after a long period of use and the protective film is laminated again, the inner diameter of the hole 15 is not excessively expanded, The number of recycling operations is increased, resources are saved, and durability is improved.

In the aluminum member 10, the hydrate 22 (see FIG. 2) in which the salt and the moisture are combined is removed in the porous anodization layer 20 while the porous anodization layer 20 is etched, thereby lowering the water content of the protective coating. Therefore, even when the aluminum member 10 is used in the deposition chamber, cracks on the surface of the aluminum member and generation of particles in the deposition chamber are suppressed, and the material of the film formed by the operation in the deposition chamber .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the present invention. Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

10: aluminum member 11: base metal
20: porous anodization layer 22: salt hydrate
26: pore 30: nonporous anodization layer

Claims (9)

A base material made of a bare aluminum alloy and a protective film laminated on the surface of the base material,
Wherein the protective coating is a porous anodization layer formed of porous aluminum oxide having a plurality of pores formed on the surface of the base material and having a thickness of 1 to 7 占 퐉; And
And a nonporous anodization layer made of nonporous aluminum oxide and having a thickness of 200 to 700 nm, which is laminated on the inner circumferential surface of the plurality of pores and the partition wall between the plurality of pores,
And an inlet of the plurality of pores is not closed by the non-porous anodization layer. The method according to claim 1,
Wherein the porous anodization layer does not include a hydrate in which salt and water (H ₂ O) are combined with each other formed by reaction of aluminum (Al) and acid. A method of producing an aluminum member having a protective coating on its surface,
A porous anodic oxidation layer having a thickness of 1 to 7 탆 and made of porous aluminum oxide having a plurality of pores formed on the surface of a base material made of a bare aluminum alloy is laminated A porous anodization layer stacking step;
A porous anodization layer etching step of etching the porous anodization layer so that an inner diameter of the plurality of pores is expanded; And
An anodic oxidation layer stacked on the inner circumferential surface of a plurality of pores having an expanded inner diameter and a partition wall between the plurality of pores, the nonporous anodization layer made of nonporous aluminum oxide and having a thickness of 200 to 700 nm; Comprising:
Characterized in that the inlet of the plurality of pores is not closed by the non-porous anodization layer. The method of claim 3,
The porous anodization layer laminating step includes an acid electrolytic solution electrolysis step of immersing the base material in an acidic electrolyte and electrolyzing the base material as an anode,
Wherein the step of laminating the nonporous anodization layer comprises a neutral electrolytic solution electrolysis step of immersing the base material in which the porous anodization layer is laminated in a neutral electrolyte and electrolyzing the base material as an anode. A method of manufacturing an aluminum member having a protective coating. 5. The method of claim 4,
The acidic electrolytic solution is an aqueous solution of sulfuric acid (H ₂ SO ₄ )
In the acid electrolyte electrolytic step, salts formed with an aluminum (Al) and the sulfuric acid in the base material reaction _{(Al 2 (SO 4) 3} ) and water (H ₂ O) is bonded hydrate (Al ₂ (SO _{4) 3} ? NH ₂ O, n is a natural number) is laminated on the inner peripheral surface of the plurality of pores,
Wherein the hydrate (Al ₂ (SO ₄ ) ₃ ? NH ₂ O) is removed from the porous anodization layer in the porous anodization layer etching step. 5. The method of claim 4,
The acidic electrolytic solution is an aqueous solution of H ₂ C ₂ O ₄ ,
In the acid electrolyte electrolysis step, an aluminum (Al) and the fish are salts formed by reaction of the base material _{(Al 2 (C 2 O 4} ) 3) and water (H ₂ O) is a hydrate (Al ₂ (C bond ₂ O ₄ ) ₃ ? N H ₂ O, n is a natural number) is laminated on the inner peripheral surface of the plurality of pores,
Wherein the hydrate (Al ₂ (C ₂ O ₄ ) ₃ ? NH ₂ O) is removed from the porous anodization layer in the porous anodization layer etching step. 5. The method of claim 4,
Further comprising a heat treatment step of heat treating the base material on which the porous anodization layer and the non-porous anodization layer are laminated in a vacuum environment or an environment filled with nitrogen gas after the step of laminating the non-porous anodization layer, To the aluminum member. The method of claim 3,
Wherein the step of etching the porous anodization layer comprises the step of introducing an aqueous solution of phosphoric acid (H ₃ PO ₄ ) into the porous anodization layer as an etching agent. 9. The method of claim 8,
Wherein the step of etching the porous anodization layer comprises the step of applying the aqueous phosphoric acid solution to the porous anodization layer at a concentration of 3 to 20 wt% and at a temperature of 50 to 100 DEG C for 1 to 10 minutes. Wherein the aluminum member is made of aluminum.

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