A method for manufacturing an aluminum or aluminum alloy substrate having a surface layer, and an aluminum alloy or aluminum substrate obtained by this manufacturing method.

Abstract

To provide a method for manufacturing an aluminum or aluminum alloy substrate having a surface layer that can be produced simply and inexpensively and exhibits stable infrared radiation, and to provide an aluminum or aluminum alloy substrate having a surface layer obtained by this manufacturing method. [Solution] A method for producing an aluminum or aluminum alloy substrate having a surface layer, characterized by performing a pretreatment step of heating a solid material to be treated, selected from aluminum and aluminum alloys, in an air atmosphere, at standard atmospheric pressure, and at 220°C to 450°C for 0.5 to 10 hours, and a main treatment step of treating the material after the pretreatment step with a treatment solution selected from an aqueous solution of sodium hydroxide, an aqueous solution of potassium hydroxide, and a mixed solution of sodium hydroxide or potassium hydroxide and water glass at 50°C to 150°C, thereby providing a surface layer on the surface of the aluminum or aluminum alloy.

Description

Technical Field

[0001] The present invention relates to a method for producing an aluminum or aluminum alloy substrate having a surface layer, and to an aluminum or aluminum alloy substrate having a surface layer obtained by this production method, and particularly relates to a method for producing an aluminum or aluminum alloy substrate having a surface layer, which is used for heat dissipation of electronic and electrical equipment, and to an aluminum or aluminum alloy substrate having a surface layer obtained by this production method.

Background Art

[0002] Many electronic and electrical devices that are indispensable in various modern technical fields generate heat during operation, and in order to efficiently dissipate the heat generated in these devices and their components, the use of, for example, heat sink members is essential.

[0003] In the manufacture of heat sinks, since lightweight materials with excellent thermal conductivity are useful, aluminum is preferred and utilized as a base material. In order to improve the heat dissipation performance of aluminum, for example, a method is adopted in which an aluminum substrate is subjected to anodizing treatment (alumite treatment) to form an oxide film as a surface layer (for example, Patent Document 1).

[0004] In addition, as a method other than the alumite treatment, a method is used in which a zinc displacement plating bath is prepared by dissolving zinc oxide in a sodium hydroxide solution, and an aluminum substrate is treated using this zinc displacement plating bath. According to this method, a metal zinc layer is formed on the surface of the aluminum substrate, whereby the heat dissipation performance of the aluminum substrate is ensured (for example, Patent Document 2).

[0005] Further, Patent Document 3 describes a technique for producing a cooling aluminum member or the like having a film with a far-infrared radiation function by treating the surface of a predetermined metallic aluminum or aluminum alloy substrate with aluminum hydroxide or the like.

Prior Art Documents

[0006] [Patent Document 1] Patent No. 2009-108386 [Patent Document 2] Patent No. 2011-52264 [Patent Document 3] Patent No. 5083578 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, the anodizing process described in Patent Document 1 requires a large-scale apparatus for electrolytic treatment, which increases manufacturing costs.

[0008] Furthermore, the surface treatment described in Patent Document 2 requires special treatments, such as treatment with a zinc-substituted sodium hydroxide plating bath, which complicates the manufacturing process.

[0009] Furthermore, although the method described in Patent Document 3 allows for the acquisition of predetermined far-infrared radiation performance by the coating formed on the substrate, there is room for improvement in order to obtain even more stable radiation performance.

[0010] Therefore, the object of the present invention is to provide a method for manufacturing an aluminum or aluminum alloy substrate having a surface layer that can be manufactured simply and inexpensively and exhibits stable infrared radiation, and to provide an aluminum or aluminum alloy substrate having a surface layer obtained by this manufacturing method, and a heat dissipation member obtained from these substrates. [Means for solving the problem]

[0011] The inventors of this invention have conducted extensive research to solve the aforementioned problems, and as a result, they have found that the problems of this invention are: (1) A pretreatment step in which a solid material to be treated, selected from aluminum and aluminum alloys, is heated in an air atmosphere at standard atmospheric pressure and at 220°C to 450°C for 0.5 to 10 hours, (2) The main treatment step involves treating the material to be treated after the pretreatment step with a treatment solution selected from an aqueous solution of sodium hydroxide at 40°C to 150°C, an aqueous solution of potassium hydroxide, and a mixed solution of sodium hydroxide or potassium hydroxide and water glass. By performing the above steps, we discovered that the problem can be solved by a method for manufacturing an aluminum or aluminum alloy substrate having a surface layer, characterized by providing a surface layer on the surface of aluminum or an aluminum alloy, and thus completed the present invention.

[0012] The material to be treated in the manufacturing method of the present invention is aluminum or an aluminum alloy, and is particularly preferably an aluminum alloy containing aluminum as the main component and one or more selected from magnesium, silicon, manganese, nickel, zinc, and copper as minor components.

[0013] Furthermore, it is preferable that the mass ratio of the main component aluminum to the secondary components of the aluminum alloy to be treated is (80:20) to (99:1), and particularly (95:5) to (99:1).

[0014] Furthermore, it is preferable that the material to be treated in the manufacturing method of the present invention is aluminum with an impurity content of 1% by mass or more.

[0015] Furthermore, the above-mentioned problems of the present invention are achieved by an aluminum or aluminum alloy substrate having a surface layer, obtained by the manufacturing method described above.

[0016] It is preferable that the aluminum alloy substrate of the present invention contains magnesium and silicon as auxiliary components.

[0017] Furthermore, the problems of the present invention are solved by a heat dissipation member obtained from an aluminum or aluminum alloy substrate having the surface layer of the present invention. [Effects of the Invention]

[0018] According to the production method of the present invention, it is possible to provide an aluminum or aluminum alloy base material having a surface layer exhibiting excellent infrared radiation properties without relying on large-scale equipment or complicated treatments. Furthermore, the aluminum or aluminum alloy base material obtained by the production method of the present invention exhibits particularly excellent infrared radiation properties due to its surface layer, and demonstrates superior heat dissipation / radiation performance when applied to heat dissipation plates and the like. In addition, the aluminum or aluminum alloy base material obtained by the production method according to the preferred embodiment of the present invention, or the heat dissipation plate obtained from the base material, is excellent in the temporal stability of heat dissipation / radiation performance and the uniformity of heat dissipation. [Brief Description of the Drawings]

[0019] [Figure 1] Figures 1(a) to (c) are optical micrographs substituted for drawings for explaining the evaluation criteria for the surface properties of aluminum or aluminum alloy base materials produced in Examples and Comparative Examples. [Mode for Carrying Out the Invention]

[0020] The present invention will be described in further detail.

[0021] The present invention relates to a method for producing an aluminum or aluminum alloy base material having a surface layer, the production method comprising: (1) A pretreatment step of heating a solid material to be treated selected from aluminum and aluminum alloys at standard atmospheric pressure at 220°C to 450°C for 0.5 to 10 hours in an air atmosphere; and (2) A main treatment step of treating the material to be treated after the pretreatment step with a treatment solution at 50°C to 150°C, that is, an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, or a mixed solution of sodium hydroxide or potassium hydroxide and water glass, whereby a surface layer is provided on the surface of the aluminum or aluminum alloy that is the material to be treated.

[0022] In other words, in the manufacturing method of the present invention, a surface layer is formed on the surface of an aluminum or aluminum alloy substrate by applying a pretreatment step and a main treatment step to the aluminum or aluminum alloy substrate, which is the material to be treated. In the present invention, "substrate" refers to a material that serves as the base / foundation for a product or part, and there are no particular restrictions on its use or shape, but in the present invention it is mainly used as a heat sink / heat dissipation plate. Furthermore, in the present invention, the entire material including both the surface layer and the aluminum or aluminum alloy portion after pretreatment and posttreatment is called the substrate, and the raw material or aluminum or aluminum before posttreatment is completed is called the material to be treated.

[0023] <Material to be treated> The material to be treated in this invention is aluminum or an aluminum alloy that is solid at room temperature.

[0024] In the case of aluminum being used as the material to be treated, it is preferable to use aluminum with an impurity content of 1% by mass or more, and particularly 1 to 20% by mass. By using aluminum with such an impurity content as the material to be treated, it is possible to manufacture an aluminum substrate (hereinafter also referred to as "aluminum substrate") having a surface layer with particularly excellent infrared emissivity (hereinafter also referred to as "emissivity").

[0025] While it is possible to use aluminum with a purity of approximately 90% to 99.9% or higher, commonly referred to as pure aluminum, as the base material for the present invention, the higher the purity, the higher the material cost, and the more limited the effects obtained through pretreatment tend to be. In other words, the present invention makes it possible to obtain a base material with excellent emissivity using low-purity aluminum as the raw material, thereby improving cost-effectiveness.

[0026] Furthermore, when using an aluminum alloy as the material to be treated, it is preferable to use a material that contains aluminum (Al) as the main component and one or more of magnesium (Mg), silicon (Si), manganese (Mn), nickel (Ni), zinc (Zn), or copper (Cu) as minor components. Specifically, examples include binary alloys such as Al-Mg, Al-Si, Al-Mn, and Al-Cu; ternary alloys such as Al-Mg-Si, Al-Mn-Mg, Al-Cu-Mg, and Al-Zn-Mg; quaternary alloys such as Al-Zn-Mg-Cu; and pentary alloys such as Al-Si-Cu-Mg-Ni, with Al-Mg-Si being particularly preferred.

[0027] Furthermore, when an aluminum alloy is used as the material to be treated, the mass ratio of the main component aluminum to the minor component is preferably in the range of (80:20) to (99:1), and particularly preferably in the range of (95:5) to (99:1). By setting the mass ratio of the main component to the minor component as described above, it is possible to manufacture an aluminum alloy substrate (hereinafter also referred to as "aluminum alloy substrate" or "alloy substrate") having a surface layer with particularly excellent emissivity.

[0028] <(1) Pre-treatment process> In this invention, the material to be treated is heated in an air atmosphere, at standard atmospheric pressure, at a treatment temperature of 220°C to 450°C, preferably 230°C to 350°C, and particularly preferably 250°C to 330°C, for a treatment time of 0.5 to 10 hours, preferably 1 to 7 hours, and even more preferably 1.5 to 5.5 hours, using a heating furnace (for example, a small box furnace KBF1150°C series (manufactured by JTEKT Thermo Systems Co., Ltd.)). This step is referred to as the pretreatment step in this invention.

[0029] By using the above processing temperature and processing time, the emissivity of the aluminum and aluminum alloy substrates obtained after this processing step (collectively referred to as "the substrates of the present invention") is improved.

[0030] In the pretreatment of the present invention, the treatment time refers to the time from when the material to be treated is placed in the heating furnace until it is removed from the heating furnace, and the treatment time is maintained for the above period.

[0031] In this invention, the following processes are usually performed after pretreatment and before the main process, but they are not necessarily required.

[0032] <Cooling (Resting) Process> The material to be treated is removed from the heating furnace and, for example, in the case of a plate with a thickness of 1 mm to 30 mm, it is allowed to cool for about 5 to 30 minutes, preferably 10 to 20 minutes. This cools the material to, for example, 50°C or below, preferably 30°C or below.

[0033] <Preparation of the treatment solution> The processing solution used in the main step of this invention can be prepared in advance, for example, as follows. Preparation of sodium hydroxide aqueous solution: When preparing an aqueous sodium hydroxide solution as the treatment solution, add 100 to 300 g of water to 50 g of a 0.1 to 5 mol / L, preferably 0.3 to 3 mol / L, aqueous sodium hydroxide solution.

[0034] Preparation of potassium hydroxide aqueous solution: A potassium hydroxide aqueous solution can be prepared by using potassium hydroxide in the same proportion as sodium hydroxide as described in the above example of preparing a sodium hydroxide aqueous solution.

[0035] Examples of preparing aqueous sodium hydroxide solution or a mixed solution of potassium hydroxide and water glass: A mixed solution of sodium hydroxide aqueous solution or potassium hydroxide and water glass can be prepared by mixing the sodium hydroxide aqueous solution or potassium hydroxide prepared according to the above preparation example with, for example, 0.15 to 1.7 mol / L water glass (sodium silicate aqueous solution) in equal volumes.

[0036] <(2) Main Processing Step> In this processing step, the surface treatment of the material to be treated is performed by immersing it in a bath of the above-mentioned treatment solution at 40°C to 150°C, preferably 50°C to 120°C, for 30 minutes to 200 minutes, preferably 80 minutes to 180 minutes. In addition, the surface treatment of the material to be treated with the treatment solution is generally performed on the entire surface of the material to be treated by immersion in a treatment container, but in some cases it can also be performed by spraying or coating using a spraying device.

[0037] In this processing step, the aluminum on the surface of the material to be treated reacts with sodium hydroxide and potassium hydroxide in the treatment solution, thereby forming a surface layer of aluminum hydroxide on the surface of the aluminum or aluminum alloy substrate.

[0038] In this invention, the radioactivity of the formed surface layer is improved by performing the above-described pretreatment step followed by the main treatment step under the above-described conditions.

[0039] In particular, the present invention is characterized by performing a heat treatment (pretreatment) of the aluminum substrate as a step in the main treatment process. However, this pretreatment differs from the aging treatment, which is generally known as a surface treatment for aluminum, in both its purpose and treatment conditions (treatment temperature and treatment time). For example, in the aging treatment, which is known as a means of age-hardening aluminum alloys, heat treatment is generally performed at temperatures below 200°C. The pretreatment of the present invention is characterized by being performed in the temperature range of so-called over-aging treatment (220°C to 450°C), which differs from the temperature conditions of such aging treatment. In other words, the pretreatment of the present invention is a different treatment from the generally known aging treatment of aluminum alloys, and is performed with the aim of promoting the reaction between aluminum and sodium hydroxide, etc., in the main treatment of the present invention. As a result, the substrate of the present invention is said to have excellent radioactivity.

[0040] Furthermore, it is preferable that the surface layer of the substrate of the present invention is formed in a smooth state over its entire surface. That is, it is preferable that the precipitation of aluminum oxide is uniform over the entire surface of the material to be treated. As a result, the substrate of the present invention is made to have excellent and uniform radioactivity over its entire surface, and when applied, for example, as a heat sink, it can dissipate heat from the equipment or components to which it is applied evenly and uniformly.

[0041] Furthermore, if processing conditions other than the temperature and time described above are used for the pre-treatment step of the present invention, sufficient radioactivity may not be obtained even if the properties of the surface layer are good.

[0042] In this invention, the emissivity of the substrate of the present invention is increased by performing a pretreatment on an aluminum or aluminum alloy material to be treated, followed by the main treatment. The mechanism is described below.

[0043] Even pure aluminum contains a certain amount of impurities. Furthermore, aluminum alloys generally exist as solid solutions in which other metallic elements (impurities or by-components) are dissolved in aluminum. When treating aluminum, particularly aluminum with an impurity content of 1% by mass or more, or aluminum alloys, with a treatment solution, we have found that in conventional methods of direct treatment without pretreatment, the reaction between aluminum and sodium hydroxide or potassium hydroxide at the atomic level is inhibited due to the aluminum being in a solid solution state. As a result, it is difficult to form a surface layer that enhances radiative performance.

[0044] However, in this invention, by performing a heat treatment as a pretreatment, impurities or by-components (Mg, Si, etc.) that were solid-solved in the aluminum precipitate, i.e., are discharged outside the aluminum. As a result, a portion of the solid solution becomes exposed as elemental aluminum crystals. Since this exposed aluminum reacts more readily with sodium hydroxide or potassium hydroxide than the solid solution, an environment is created in which a surface layer that enhances radiative performance is easily formed.

[0045] For example, when the pretreatment of the present invention is applied to a material to be treated, such as an aluminum-magnesium alloy, magnesium by-components dissolved in the aluminum precipitate, and a portion of the solid solution becomes exposed, revealing elemental aluminum crystals. It is presumed that performing the main treatment step in this pretreated state promotes the reaction between aluminum and sodium hydroxide or potassium hydroxide in the treatment solution.

[0046] Furthermore, when using ternary or pentary alloys such as aluminum-magnesium-silicon as the material to be treated, it is presumed that in methods without pretreatment, multiple minor components (such as Mg and Si) with atomically different sizes form solid solutions with aluminum, thereby particularly inhibiting the formation of a surface layer through reaction with sodium hydroxide, etc. In the present invention, even if aluminum in the aluminum alloy forms solid solutions with multiple types of minor components due to the heat treatment in the pretreatment, the minor components precipitate on the outside of the aluminum, exposing elemental aluminum crystals in part of the solid solution. This significantly enhances the effect of pretreatment compared to conventional treatments, and promotes the reaction between aluminum and the treatment solution such as sodium hydroxide in the main treatment step.

[0047] In this invention, after preparing the material to be treated in a reaction-friendly state through a pretreatment step, sodium hydroxide treatment is performed, which causes strong ionic bonds to be formed between the aluminum ions of the aluminum or aluminum alloy and the hydroxide ions of sodium hydroxide, thereby stably forming a surface layer with sufficient thickness, for example, 10 to 40 μm, preferably 15 to 35 μm, and more preferably 18 to 30 μm, on the aluminum or aluminum alloy. Having a surface layer of the above thickness improves the radioactivity of the resulting aluminum substrate or alloy substrate. The thickness of the surface layer in this invention is measured using a commercially available film thickness measuring instrument, for example, SWT300 (product name, manufactured by Sanko Electronics Laboratory).

[0048] Furthermore, in the present invention, a post-processing step may be provided after the main processing step, for example, as follows.

[0049] <(3) Post-processing steps> After this process, the following post-processing steps may be performed at any time, not in the order listed below.

[0050] <(3)-1:Curing> After this processing step, the aluminum or aluminum alloy can be removed from the processing solution and then subjected to heating or hydrothermal treatment. For heating or hydrothermal treatment, for example, heating conditions of 50°C to 150°C or 70°C to 90°C for about 10 to 14 hours, or hydrothermal conditions of 100°C to 250°C or 60°C to 200°C for about 10 to 14 hours can be used.

[0051] <(3)-2: Washing / Stopping the reaction> By immersing the material to be treated after removing it from the treatment solution in distilled water or the like, precipitates and other substances not fixed to the material can be removed. The reaction in this treatment process can also be completely stopped by immersing the material immediately after removal from the treatment solution in distilled water maintained at a temperature of 25°C or below for 20 minutes to 1 hour.

[0052] <(3)-3: Smoothing> The surface smoothness of the treated material can be improved by immersing it in a bath of distilled water or the like, or by scrubbing it with a brush or sponge under running water, or by applying pressure with a plate-like material.

[0053] <(3)-4: Drying> The treated material after this treatment, or the treated material after any of the above treatments with distilled water, can be dried at room temperature or with hot air at 50-100°C.

[0054] Furthermore, the pretreatment and main treatment processes may be performed not only on the entire surface of the material to be treated, but also on only a portion of it. Alternatively, the pretreatment process may be performed on the entire surface of the material to be treated, while the main treatment process involves applying or spraying the treatment solution only on a portion of that surface. The specific treatment method can be selected according to the application.

[0055] The aluminum or aluminum alloy substrate obtained by the manufacturing method of the present invention has an excellent emissivity of 0.85 or higher, and particularly 0.9 or higher, as described in the basic patent. In this invention, the infrared emissivity of the alloy substrate is measured using a commercially available emissivity meter, such as D&S AERD (product name, manufactured by Kyoto Electronics Manufacturing Co., Ltd.).

[0056] According to the manufacturing method of the present invention described above, an aluminum or aluminum alloy substrate with excellent emissivity can be obtained in a simpler manner than conventional methods. Furthermore, the aluminum or aluminum alloy substrate of the present invention exhibits excellent heat dissipation / radiation performance as a heat dissipation member (heat sink, etc.) for computer CPUs and electronic components, LED lighting equipment, automobile batteries, etc. Moreover, since the surface layer of the aluminum or aluminum alloy substrate of the present invention is obtained in a smooth state, there is no unevenness in emissivity depending on the location of the substrate, and heat dissipation is performed uniformly throughout, and excellent radiant performance is also exhibited over time. [Examples]

[0057] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples, unless otherwise specified, "%" in relation to blending amount and content means "mass %", and proportions (ratios) are also based on mass.

[0058] [Examples 1-17, Comparative Examples 1-4] 1. Manufacturing of aluminum / aluminum alloy substrates <Pre-treatment process> Table 1 shows the materials to be treated in Examples 1 to 17 and Comparative Examples 1 and 2. The aluminum or aluminum alloys (each measuring 50 mm x 100 mm x 2 mm) were placed in a heating furnace (small box furnace KBF1150°C series (manufactured by JTEKT Thermo Systems Co., Ltd.) that had been preheated to the heating temperature listed in Table 1, and then heated by holding them in the heating furnace for the time listed in Table 1.

[0059] On the other hand, no pretreatment was performed on the materials to be treated in Comparative Examples 3 and 4.

[0060] The details of the materials used are as follows:

[0061] A6063 material (Al-Si-Mg)....Si:0.2~0.6%, Mg:0.45~0.9% ADC12 material (Al-Si-Mg)....Si:9.6~12.0%, Mg:0.3% or less A5052 material (Al-Mg): Mg: 2.2-2.8% A1050 material (Al + impurities): Impurities make up approximately 0.5% or less of the total material composition. The detailed chemical composition of the above-mentioned 6063, ADC12, 5052, and 1050 materials is as specified in JIS H4100, JIS H5302, and JIS H4000.

[0062] <Observation of the treated material> When the surface of the pre-treated materials (Examples 1-17, Comparative Examples 1-4) was observed with an optical microscope ECLIPSE LV150N, it was confirmed that Si, Mg, or impurities had precipitated on the surface of the treated materials, appearing as layers or minute precipitates. In Examples 1 to 17, it was observed that the by-components precipitated uniformly, covering the surface of the treated material.

[0063] <Intermediate processing (cooling / curing) process> The pre-treated material was removed from the heating furnace and allowed to cool for approximately 15 minutes in a room adjusted to 25°C and atmospheric pressure.

[0064] <Main processing / Post-processing steps> A treatment solution bath was prepared by adding 200g of distilled water to 50g of a commercially available sodium hydroxide aqueous solution (0.5 mol / L). The material to be treated after the intermediate treatment process was immersed in the treatment solution, heated to the temperature listed in Table 1, for the treatment time listed in the same table. After that, the material to be treated was removed from the treatment solution bath and rinsed with distilled water to wash away the treatment solution, and then left at room temperature for about 12 hours to dry.

[0065] This yielded substrates for Examples 1-17 and Comparative Examples 1-4 (Comparative Examples 3-4 underwent only this treatment), which had a surface layer on the surface of aluminum or an aluminum alloy. 2. Evaluation of aluminum / aluminum alloy substrates

[0066] <Evaluation of surface layer composition> We used an X-ray diffractometer (RINT-2200, Rigaku Corporation) to identify the products present on the surface layer of the treated material. X-ray diffraction measurements were performed with an incident angle of 2° and a scanning range of 10-90°.

[0067] In the treated materials of the present invention (A6063, ADC12, A5052, and A1050), X-ray diffraction patterns of byerlite and gibbsite, which are aluminum hydroxide (trihydrated aluminum oxide) Al(OH)3, were observed. From this, it was confirmed that a surface layer composed of aluminum hydroxide (trihydrated aluminum oxide) Al(OH)3 was formed on the treated materials obtained in the examples.

[0068] <Emissivity measurement> The emissivity of the substrates in the examples and comparative examples was measured using an emissivity meter (product name "D&S AERD", manufactured by Kyoto Electronics Manufacturing Co., Ltd.).

[0069] The measurement results were expressed according to the following criteria and are listed in Table 1. 〇: 0.88 or higher △: 0.85 or higher and less than 0.88 ×: Less than 0.85

[0070] In particular, the substrate of Comparative Example 3 (without pretreatment) showed a remarkably low emissivity of 0.708. The substrate of Comparative Example 4 (without pretreatment) also showed a remarkably low emissivity of 0.720.

[0071] <Observation of surface properties> The outer surface of the surface layer of the substrates in the examples and comparative examples was visually observed and imaged using an optical microscope ECLIPSE LV150N (product name, manufactured by NICON Corporation).

[0072] The measurement results were expressed according to the following criteria and are listed in Table 1. ○: Good (smooth surface) △: Fairly good (some inconsistency) ×: Defective (unevenness, with areas where crystal growth has not occurred (indented areas))

[0073] Furthermore, Figures 1(a) to (c) show optical microscope images illustrating the above evaluation criteria. Specifically, Figures 1(a) to (c) show the surface condition of the substrate evaluated as follows: 0.5 hours at 300°C (○: good (smooth surface)), 1 hour at 300°C (△: somewhat good (some unevenness)), and 2 hours at 300°C (×: poor (very uneven)).

[0074] <Film thickness measurement> The film thickness of the surface layer of each substrate in the examples and comparative examples was measured using a film thickness measuring instrument SWT300 (product name, manufactured by Sanko Electronics Laboratory).

[0075] In particular, the substrate of Comparative Example 3 (without pretreatment) had a surface layer with a remarkably small film thickness of 4.0 μm. The substrate of Comparative Example 4 (without pretreatment) also had a surface layer with a similarly small film thickness of 5.5 μm.

[0076] [Table 1]

[0077] The experimental results above show that the substrates of Examples 1 to 17 of the present invention have excellent surface properties and radioactivity. In contrast, the substrates of Comparative Examples 1 to 4 showed results that could not be considered sufficient for evaluating radioactivity.

[0078] In particular, as is evident from the comparison between Examples 1-10 and Example 15 and Comparative Examples 3 and 4 (no pretreatment), the aluminum substrates and aluminum alloy substrates obtained by performing the pretreatment of the present invention exhibit excellent radioactivity.

[0079] Although the present invention has been described in detail above based on embodiments, it goes without saying that the present invention is not limited to the above embodiments and can be modified in various ways without departing from its essence.

Claims

1. (1) A pretreatment step in which a solid material to be treated, selected from aluminum and aluminum alloys, is heated in an air atmosphere at standard atmospheric pressure and at 220°C to 450°C for 0.5 to 10 hours, (2) The main treatment step involves treating the material to be treated after the pretreatment step with a treatment solution selected from an aqueous solution of sodium hydroxide at 40°C to 150°C, an aqueous solution of potassium hydroxide, and a mixed solution of sodium hydroxide or potassium hydroxide and water glass, A method for manufacturing an aluminum or aluminum alloy substrate having a surface layer, characterized by providing a surface layer on the surface of the aluminum or aluminum alloy by performing the following steps.

2. The manufacturing method according to claim 1, characterized in that the material to be treated is an aluminum alloy, and the aluminum alloy is an aluminum alloy containing aluminum as a main component and one or more selected from magnesium, silicon, manganese, nickel, zinc, and copper as minor components.

3. The manufacturing method according to claim 2, characterized in that the mass ratio of the main component aluminum to the minor component is (80:20) to (99:1).

4. The manufacturing method according to claim 2, characterized in that the mass ratio of the main component aluminum to the minor component is (95:5) to (99:1).

5. The manufacturing method according to claim 1, characterized in that the material to be treated is aluminum with an impurity content of 1% by mass or more.

6. An aluminum or aluminum alloy substrate having a surface layer, characterized by being obtained by a manufacturing method described in any one of claims 1 to 5.

7. The aluminum alloy substrate according to claim 6, characterized in that the aforementioned auxiliary components include magnesium and silicon.

8. A heat dissipation member obtained from an aluminum or aluminum alloy substrate having the surface layer described in claim 6.

Images