Aluminum material with coating and manufacturing method of aluminum material with coating

Abstract

To provide an aluminum material with a coating capable of enhancing a corrosion resistance of a coating arranged on the aluminum material, and a manufacturing method of the aluminum material with the coating.SOLUTION: An aluminum material with a coating has an aluminum material and the coating arranged on a surface of the aluminum material. The aluminum material is composed of a pure aluminum with an international aluminum alloy name with an aluminum base number of 1000's. The coating contains boehmite. An intensity ratio R represented with an equation (1) below is 0.3 or less. Intensity ratio R=peak intensity Y / peak intensity X (1). The peak intensity X and the peak intensity Y in the equation (1) are peak intensities of an X-ray diffraction chart of the coating. The peak intensity X is an inherent peak intensity derived from an aluminum (200) plane. The peak Y is an inherent peak intensity derived from a boehmite (020) plane.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a coated aluminum material and a method for manufacturing a coated aluminum material. [Background technology]

[0002] As described in Patent Document 1, for example, a coated aluminum alloy material is known that has an aluminum alloy with an international aluminum alloy name of the 2000 series, 6000 series, or 7000 series and a coating formed on the aluminum alloy. In this coated aluminum alloy material, the coating is made of boehmite (aluminum oxide monohydrate, AlOOH) and an Al-based layered double hydroxide, thereby improving the corrosion resistance of the coating. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2017 / 135363 Summary of the Invention [Problem to be solved by the invention]

[0004] In addition to the aluminum alloy materials with international aluminum alloy names in the 2000 series, aluminum materials in the 1000 series are also known. Aluminum materials in the 1000 series are pure aluminum materials with a purity of 99.00% or more. In coated aluminum materials in which a coating containing boehmite is provided on such aluminum materials in the 1000 series, it is desirable to improve the corrosion resistance of the coating. [Means for solving the problem]

[0005] The coated aluminum material that solves the above-mentioned problems is a coated aluminum material having an aluminum material and a coating provided on the surface of the aluminum material, wherein the aluminum material is made of pure aluminum having an International Aluminum Alloy Name of 1000 series, the coating contains boehmite, and the strength ratio R of the coating, expressed by the following formula (1), is 0.3 or less.

[0006] Intensity ratio R = peak intensity Y / peak intensity X (1) (The peak intensity X and peak intensity Y in formula (1) are peak intensities in an X-ray diffraction chart of the coating, the peak intensity X is the intrinsic peak intensity derived from the (200) plane of aluminum, and the peak intensity Y is the intrinsic peak intensity derived from the (020) plane of boehmite.) [Effects of the Invention]

[0007] The present invention exhibits the effect of making it possible to improve the corrosion resistance of a coating provided on an aluminum material. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an X-ray diffraction chart of the coating of the sample of Test Example 1. [Figure 2] FIG. 2 is a photomicrograph showing a cross section of the sample of Test Example 1. [Figure 3] FIG. 3 is an X-ray diffraction chart of the coating of the sample of Test Example 2. [Figure 4] FIG. 4 is a photomicrograph showing a cross section of the sample of Test Example 2. [Figure 5] FIG. 5 is an X-ray diffraction chart of the coating of the sample of Test Example 3. [Figure 6] FIG. 6 is a photomicrograph showing a cross section of the sample of Test Example 3. [Figure 7] FIG. 7 is a schematic cross-sectional view showing an example of a film forming apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of a coated aluminum material and a method for manufacturing a coated aluminum material will be described. <Coated aluminum material> A coated aluminum material has an aluminum material and a coating formed on the surface of the aluminum material. The aluminum material is made of pure aluminum with an international aluminum alloy name of the 1000 series. Pure aluminum in the 1000 series has a purity of 99.00% or more. Examples of pure aluminum in the 1000 series include 1050 (A1050), 1060 (A1060), 1070 (A1070), 1080 (A1080), 1050A (A1050A), 1100 (A1100), 1200 (A1200), and 1230A (A1230A).

[0010] The coating contains boehmite, which is aluminum oxide monohydrate (AlOOH). The coating has an intensity ratio R, expressed by the following formula (1), of 0.3 or less.

[0011] Intensity ratio R = peak intensity Y / peak intensity X (1) The peak intensity X and peak intensity Y in formula (1) are peak intensities in an X-ray diffraction chart of the coating. Peak intensity X is the intrinsic peak intensity derived from the (200) plane of aluminum. Peak intensity X is the reflection peak intensity observed at around 2θ = 45°. Peak intensity Y is the intrinsic peak intensity derived from the (020) plane of boehmite. Peak intensity Y is the reflection peak intensity observed at around 2θ = 14°. This coating contains boehmite and aluminum.

[0012] The intensity ratio R is preferably within a range of, for example, 0.01 to 0.3. The upper limit of the intensity ratio R may be, for example, 0.2, 0.1, etc. The lower limit of the intensity ratio R may be, for example, 0.03, 0.05, etc.

[0013] The thickness of the coating is, for example, in the range of 0.5 μm or more and 100 μm or less. The coated aluminum material may be in the form of, for example, a plate, a tube, a rod, etc. Specific examples of the coated aluminum material include heat transfer members, heat dissipation members, conductive members, decorative members, etc.

[0014] The aluminum material of the coated aluminum material may be a flow path pipe. The flow path pipe can be used, for example, as a heat transfer member of a heat exchanger. When the aluminum material is a flow path pipe, the coating can be provided on at least a part of the outer circumferential surface and the inner surface of the flow path pipe. From the viewpoint of protecting the flow path pipe from a fluid such as a heat transfer medium flowing through the flow path pipe, it is preferable that the coating be provided on at least the inner surface of the flow path pipe.

[0015] <Method of manufacturing coated aluminum material> The method for producing a coated aluminum material includes a preparation step of preparing a substrate made of an aluminum material, and a coating formation step of forming a coating on the substrate. In the method for producing a coated aluminum material, it is preferable that the aluminum material prepared in the preparation step has been previously cleaned. Examples of cleaning methods for the aluminum material include cleaning with a cleaning solution containing cleaning components such as alcohol, a surfactant, and water, and cleaning with ultrasonic waves.

[0016] In the coating formation step, water vapor is brought into contact with at least a portion of the surface of the substrate. As a result, a portion of the aluminum on the surface of the substrate is oxidized to produce boehmite. That is, in the coating formation step, a coating containing boehmite is formed on the substrate, thereby obtaining a coated aluminum material.

[0017] The temperature of the steam in the film formation process is in the range of 100°C or higher and 200°C or lower. When the temperature of the steam is 100°C or higher, for example, a thicker film can be formed, thereby improving the corrosion resistance of the film. When the temperature of the steam is 200°C or lower, the formation of cracks in the film can be suppressed, thereby improving the corrosion resistance of the film.

[0018] In the coating formation process, the contact time between the substrate surface and water vapor is within the range of 0.1 to 5 hours. When the contact time is 0.1 hours or longer, for example, a thicker coating can be formed, thereby improving the corrosion protection provided by the coating. When the contact time is 5 hours or shorter, the formation of cracks in the coating can be suppressed, thereby improving the corrosion protection provided by the coating.

[0019] The contact time between the surface of the substrate and water vapor is the time elapsed after the surface reaches a predetermined temperature in the range of 100° C. to 200° C. The time required to reach the predetermined temperature in the range of 100° C. to 200° C. is, for example, preferably within 1 hour, and more preferably within 0.5 hours.

[0020] Examples of the film-forming device used in the film-forming step include a device equipped with a pressure-resistant container that generates water vapor to be brought into contact with the substrate, a spraying device that sprays water vapor onto the substrate, etc. Water, which is the source of water vapor, can be, for example, ion-exchanged water, pure water, etc.

[0021] The surface of the substrate to be subjected to the coating formation step, i.e., the surface of the substrate before contact with water vapor, may be, for example, wet with water or dry. The surface of the substrate is preferably dry, for example, from the viewpoint of allowing the reaction of aluminum in the substrate to proceed slowly.

[0022] <Test example> Next, a test example will be described. (Test Example 1) An aluminum material (a plate made of pure aluminum of A1050) was prepared as a substrate (preparation step). The aluminum material was ultrasonically cleaned using alcohol (ethanol) as a cleaning solution and then naturally dried. Next, a film was formed on the surface of the substrate by bringing the surface of the substrate into contact with water vapor (film formation step).

[0023] The film formation process was performed using a film formation apparatus 11 shown in FIG. 7. The film formation apparatus 11 includes a pressure-resistant container 12 and a heater 13. Water W, which is a source of water vapor V, is stored in the pressure-resistant container 12. The pressure-resistant container 12 includes a pressure regulating valve for adjusting the pressure inside the pressure-resistant container 12, a temperature sensor for measuring the temperature of the water vapor V inside the pressure-resistant container 12, and the like. The heater 13 is arranged so as to be able to heat the water W inside the pressure-resistant container 12.

[0024] To start the film formation process, first, the substrate 31 is held by the holder 32. Next, the substrate 31 is placed together with the holder 32 in the pressure vessel 12. At this time, the plate-shaped substrate 31 is held by the holder 32 so that both main surfaces of the substrate 31 are arranged along the vertical direction in the pressure vessel 12. Next, the water W in the pressure vessel 12 is heated using the heater 13. The film formation process is started by raising the temperature of the water vapor V in the pressure vessel 12 to a predetermined temperature.

[0025] In Test Example 1, the temperature of the water vapor V was raised to 180°C and maintained at 180°C. The contact time between the surface of the substrate 31 and the water vapor V was set to 0.5 hours, thereby obtaining a sample of a coated aluminum material. The contact time at this time was the time elapsed after the temperature of the water vapor V reached 180°C.

[0026] (Test Example 2) In Test Example 2, a sample of a coated aluminum material was obtained in the same manner as in Test Example 1, except that the contact time between the surface of the substrate and water vapor in the coating formation step was changed to 5.0 hours.

[0027] (Test Example 3) In Test Example 3, a sample of a coated aluminum material was obtained in the same manner as in Test Example 1, except that the contact time between the surface of the substrate and water vapor in the coating formation step was changed to 24.0 hours.

[0028] (Crystal structure analysis of the film using X-ray diffraction) Crystal structure analysis was performed by X-ray diffraction on the coating of each sample of Test Example 1. The X-ray source in the X-ray diffraction method was Cu-Kα, and measurements were performed under conditions of a voltage of 40 kV and a current of 40 mA.

[0029] 1 shows an X-ray diffraction chart of the coating of the sample of Test Example 1. The intensity ratio R calculated from this X-ray diffraction chart was 0.08. The coatings of the samples of Test Examples 2 and 3 were also subjected to crystal structure analysis by X-ray diffraction, as was the case with the coating of Test Example 1.

[0030] 3 shows an X-ray diffraction chart of the coating of the sample of Test Example 2. The intensity ratio R calculated from this X-ray diffraction chart was 0.09. 5 shows an X-ray diffraction chart of the coating of the sample of Test Example 3. The intensity ratio R calculated from this X-ray diffraction chart was 0.47.

[0031] (Cross-section observation of sample) The cross section of the sample of Test Example 1 was observed using a scanning electron microscope (SEM). Fig. 2 shows a cross-sectional photograph of the sample of Test Example 1. The cross sections of the samples of Test Examples 2 and 3 were also observed using a scanning electron microscope in the same manner as Test Example 1. Fig. 4 shows a cross-sectional photograph of the sample of Test Example 2. Fig. 6 shows a cross-sectional photograph of the sample of Test Example 3.

[0032] When the cross sections of the samples of Test Examples 1 and 2 were observed, no cracks were found in the coating. On the other hand, when the cross section of the sample of Test Example 3 was observed, cracks were found in the coating.

[0033] <Actions and Effects of the Embodiment> Next, the operation and effects of the embodiment will be described. (1) The coated aluminum material has an aluminum material and a coating formed on the surface of the aluminum material. The aluminum material is made of pure aluminum with an international aluminum alloy name of the 1000 series. The coating contains boehmite (AlOOH). The strength ratio R of the coating, expressed by the above formula (1), is 0.3 or less. This configuration makes it possible to suppress the occurrence of cracks in the coating. This makes it possible to improve the corrosion resistance of the coating formed on the aluminum material.

[0034] (2) The strength ratio R represented by the above formula (1) is preferably 0.01 or greater. In this case, the boehmite content in the coating or the thickness of the coating containing boehmite itself increases, making it possible to further enhance the corrosion resistance of the coating due to the boehmite.

[0035] (3) The aluminum material in the coated aluminum material may be a flow path pipe. The coating is provided on at least the inner surface of the flow path pipe. In this case, the coating exhibits corrosion resistance against the fluid flowing through the flow path pipe, thereby protecting the flow path pipe. This makes it possible to easily increase the durability of the flow path pipe made of an aluminum material.

[0036] (4) A method for producing a coated aluminum material includes a preparation step of preparing a substrate made of an aluminum material, and a coating formation step of forming a coating on the substrate. The coating formation step is a step of bringing water vapor into contact with at least a portion of the surface of the substrate. The temperature of the water vapor in the coating formation step is in the range of 100°C or higher and 200°C or lower. In the coating formation step, the contact time between the surface of the substrate and the water vapor is in the range of 0.1 hours or higher and 5 hours or lower. According to this method, a coating that suppresses the occurrence of cracks can be easily formed.

[0037] (5) If water is present on the surface of the substrate to be subjected to the coating formation process, the aluminum reaction on the substrate may be excessively accelerated during the coating formation process. In this regard, it is preferable that the surface of the substrate be dry before being brought into contact with water vapor during the coating formation process. In this case, the aluminum reaction on the substrate proceeds slowly, which makes it possible to easily prevent cracks from occurring in the coating during its growth process. [Explanation of symbols]

[0038] 31...Base material V...water vapor

Claims

1. A coated aluminum material having an aluminum material and a coating provided on a surface of the aluminum material, The aluminum material is made of pure aluminum having an international aluminum alloy name of the 1000 series, The coating contains boehmite, The coating has the following formula (1): Intensity ratio R = peak intensity Y / peak intensity X (1) (The peak intensity X and peak intensity Y in formula (1) are peak intensities in an X-ray diffraction chart of the coating, the peak intensity X is the intrinsic peak intensity derived from the (200) plane of aluminum, and the peak intensity Y is the intrinsic peak intensity derived from the (020) plane of boehmite.) The coated aluminum material has a strength ratio R of 0.3 or less.

2. The coated aluminum material according to claim 1, wherein the strength ratio R is 0.01 or more.

3. the aluminum material is a flow path pipe, The coated aluminum material according to claim 1 , wherein the coating is provided on at least the inner surface of the flow path pipe.

4. A method for producing a coated aluminum material according to any one of claims 1 to 3, a preparation step of preparing a substrate made of the aluminum material; a coating forming step of forming the coating on the substrate, the coating formation step is a step of bringing water vapor into contact with at least a part of the surface of the base material, The temperature of the water vapor is in the range of 100°C or more and 200°C or less, A method for producing a coated aluminum material, wherein the contact time between the surface of the substrate and the water vapor is within a range of 0.1 hours or more and 5 hours or less.

5. 5. The method for producing a coated aluminum material according to claim 4, wherein the surface of the substrate is in a dry state before being brought into contact with the water vapor in the coating forming step.

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