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EP-4741539-A1 - SURFACE-TREATED ALUMINUM MATERIAL, METHOD FOR PRODUCING SAME, AND COMPRESSOR WHEEL

EP4741539A1EP 4741539 A1EP4741539 A1EP 4741539A1EP-4741539-A1

Abstract

A surface-treated aluminum material (1) comprises: a base material (2), which is composed of an aluminum alloy in which the Cu content is more than 1.8 mass% and 6.8 mass% or less; and a protective film (3), which is formed on the base material. The protective film (3) comprises: an oxide layer (31), which is composed of an oxide or oxides of aluminum and covers the base material (2); and a hydrated oxide layer (32), which contains a hydrated oxide or hydrated oxides of aluminum and covers the oxide layer (31). In the situation in which cathodic polarization measurements are performed, using a prescribed measurement solution, on the base material (2) and on the surface-treated aluminum material (1) after it had been heated for 4 hours at a temperature of 200°C, the ratio J1/J2 of the current density J1 of the surface-treated aluminum material (1) to the current density J2 of the base material (2) is 7000 × 10 -5 or less.

Inventors

  • NAKAJIMA, DAIKI
  • MURATA, TAKUYA

Assignees

  • UACJ Corporation

Dates

Publication Date
20260513
Application Date
20240606

Claims (8)

  1. A surface-treated aluminum material having a base material, which is composed of an aluminum alloy in which the Cu content is more than 1.8 mass% and 6.8 mass% or less, and a protective film, which is formed on the base material, wherein: the protective film comprises: an oxide layer, which is composed of an oxide or oxides of aluminum and covers the base material; and a hydrated oxide layer, which contains a hydrated oxide or hydrated oxides of aluminum and covers the oxide layer; and in the situation in which cathodic polarization measurements are performed-using a measurement solution obtained by mixing a solution of NaCl having a concentration of 5 mass% and acetic acid having a concentration of 99.7% such that the volumetric ratio of the NaCl solution to the acetic acid = 1000:1-on the base material and on the surface-treated aluminum material after it had been heated for 4 hours at a temperature of 200°C, and the current density at the electric potential at the center of an electric-potential region of the base material that exhibits the diffusion-limited current of hydrogen ions was measured, the ratio J1/J2 of the current density J1 of the surface-treated aluminum material to the current density J2 of the base material is 7000 × 10 -5 or less.
  2. The surface-treated aluminum material according to claim 1, wherein the mass loss amount per unit of area is 0.3 g/dm 2 or less in the situation in which a sealing test is performed using the method stipulated in JIS H8683-2:2013.
  3. A compressor wheel composed of the surface-treated aluminum material according to claim 1 or 2.
  4. A method of manufacturing the surface-treated aluminum material according to claim 1 or 2, comprising: forming the oxide layer, which has pores, on the base material by performing an anodizing treatment on the base material; thereafter, heating the base material and the oxide layer at a temperature of 50°C or higher and 350°C or lower; and thereafter, contacting the oxide layer with a sealing agent, and forming the hydrated oxide layer on the oxide layer while sealing the pores.
  5. The method of manufacturing the surface-treated aluminum material according to claim 4, wherein, during the heating, the heating time from the start of heating the oxide layer to the end of heating is 1 min or more and less than 12 hours.
  6. The method of manufacturing the surface-treated aluminum material according to claim 4 or 5, wherein the sealing agent is hot water.
  7. The method of manufacturing the surface-treated aluminum material according to any one of claims 4-6, wherein, during the sealing, the oxide layer is contacted with hot water as the sealing agent that is 95°C or higher for 10 min or more and less than 120 min.
  8. The method of manufacturing the surface-treated aluminum material according to any one of claims 4-7, wherein the electrolyte solution employed in the anodizing treatment contains an inorganic electrolyte composed of an inorganic cation and one or two or more anions selected from the group consisting of a sulfate ion, a phosphate ion, an ammonium ion, and a borate ion.

Description

[TECHNICAL FIELD] The present invention relates to a surface-treated aluminum material, a method of manufacturing the same, and a compressor wheel. [BACKGROUND ART] Particularly among aluminum alloys, 2000-series aluminum alloys have the advantageous characteristic of relatively high strength at high temperatures and thus are often used for applications such as a compressor wheel of a turbocharger. In addition, 2000-series aluminum alloys are also sometimes employed for a component or components disposed inside the vacuum chamber of a semiconductor-manufacturing apparatus. Incidentally, an anodic oxide film is sometimes provided on a surface or surfaces of an aluminum material for the purpose of protecting the surface(s). For example, a component for a substrate-processing apparatus that performs plasma treatment on a substrate is disclosed in Patent Document 1, characterized by having a film that has been formed on a surface of the component by an anodizing treatment, in which the component is connected to an anode of a DC power supply and is immersed in a solution that contains an organic acid as a main component, wherein a semi-sealing treatment using boiling water is performed on the film. [PRIOR ART LITERATURE] [Patent Documents] [Patent Document 1] Japanese Laid-open Patent Publication 2008-81815 [SUMMARY OF THE INVENTION] [PROBLEMS TO BE SOLVED BY THE INVENTION] However, the component of Patent Document 1 has the problem that, because pores in the anodic oxide film are not completely closed up, durability with respect to corrosive gases and plasma is low. Meanwhile, a method that completely closes up the pores in the anodic oxide film on the component of Patent Document 1 is conceivable in order to increase durability with respect to corrosive gases and plasma. However, in this situation, cracks are more likely to form in the anodic oxide film when the temperature rises, and there is a risk that debris composed of small pieces of the anodic oxide film will be formed. In addition, in applications in which, for example, use in a high-temperature environment and slidability are required, such as for compressor wheels, if cracks form in the anodic oxide film, there is a risk that it might lead to a decrease in corrosion resistance and wear resistance. There is a desire to further increase the heat resistance of an aluminum material having an anodic oxide film on a surface or surfaces to curtail the formation of such debris or cracks. The present invention was conceived in view of this background, and it is an object to provide: a surface-treated aluminum material that excels in corrosion resistance with respect to corrosive gases and plasma and is capable of curtailing the formation of cracks even when the temperature has risen; a method of manufacturing the same; and a compressor wheel. [MEANS FOR SOLVING THE PROBLEMS] One aspect of the present invention is a surface-treated aluminum material having a base material, which is composed of an aluminum alloy in which the Cu (copper) content is more than 1.8 mass% and 6.8 mass% or less, and a protective film, which is formed on the base material, wherein: the protective film comprises: an oxide layer, which is composed of an oxide or oxides of aluminum and covers the base material; anda hydrated oxide layer, which contains a hydrated oxide or hydrated oxides of aluminum and covers the oxide layer; andin the situation in which cathodic polarization measurements are performed-using a measurement solution obtained by mixing a solution of NaCl having a concentration of 5 mass% and acetic acid having a concentration of 99.7% such that the volumetric ratio of the NaCl solution to the acetic acid = 1000:1-on the base material and on the surface-treated aluminum material after it had been heated for 4 hours at a temperature of 200°C, and the current density at the electric potential at the center of an electric-potential region of the base material that exhibits the diffusion-limited current of hydrogen ions was measured, the ratio J1/J2 of the current density J1 of the surface-treated aluminum material to the current density J2 of the base material is 7000 × 10-5 or less. Another aspect of the present invention is a compressor wheel composed of the surface-treated aluminum material according to the above-mentioned aspect. Yet another aspect of the present invention is a method of manufacturing the surface-treated aluminum material according to the aforementioned aspect, comprising: forming the oxide layer, which has pores, on the base material by performing an anodizing treatment on the base material;thereafter, heating the base material and the oxide layer at a temperature of 50°C or higher and 350°C or lower; andthereafter, contacting the oxide layer with a sealing agent, and forming the hydrated oxide layer on the oxide layer while sealing the pores. [EFFECTS OF THE INVENTION] A surface-treated aluminum material (referred to as "aluminum material" below) has a p