Aluminum Material or Aluminum Alloy Material Provided With Coating Film, Method for Producing Same, and Aqueous Surface Treatment Agent

The present invention addresses the problem of providing an aluminum material or aluminum alloy material that includes a surface treatment coating having excellent thermal corrosion resistance. The problem is solved by an aluminum material or aluminum alloy material that includes, on or over a surface thereof, a coating containing chromium, zirconium, zinc, and carbon. In an infrared spectrum of the coating measured by a specular reflection method of Fourier transform infrared spectroscopy (FT-IR), peaks appear at 3,600 cm−1 to 3,000 cm−1 and 1,750 cm−1 to 1,700 cm−1.

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Description
TECHNICAL FIELD

The present invention relates to: an aluminum material or aluminum alloy material that includes a surface treatment coating having excellent thermal corrosion resistance; and a method of producing the same. The present invention also relates to: an aqueous surface treatment agent that can form a surface treatment coating having excellent thermal corrosion resistance on or over a surface of an aluminum material or aluminum alloy material.

BACKGROUND ART

In a wide range of fields of aircraft materials, building materials, automobile components, and the like, aluminum materials and aluminum alloy materials that are surface-treated with a chromium ion-containing surface treatment agent and have a coating have been used for the purpose of providing corrosion resistance.

For example, Patent Document 1 discloses a chemical conversion treatment liquid for metal materials, which contains a component (A) composed of a water-soluble trivalent chromium compound, a component (B) composed of at least one selected from water-soluble titanium compounds and water-soluble zirconium compounds, a component (C) composed of a water-soluble nitrate compound, a component (D) composed of a water-soluble aluminum compound, and a component (E) composed of a fluorine compound, and is controlled to have a pH in a range of 2.3 to 5.0.

Patent Document 2 discloses a chemical conversion treatment liquid that contains a specific trivalent chromium compound, a specific zirconium compound, and a specific dicarboxylic acid compound in prescribed amounts.

Further, Patent Document 3 discloses a surface treatment agent for aluminum or aluminum alloys, which contains a trivalent chromium-containing ion (A), at least one ion (B) selected from titanium-containing ions and zirconium-containing ions, a zinc-containing ion (C), a free fluorine ion (D), and a nitrate ion (E).

RELATED ART DOCUMENTS Patent Documents

    • [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2006-328501
    • [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2006-316334
    • [Patent Document 3] Japanese Patent No. 6910543

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Aluminum materials and aluminum alloy materials may be exposed to a high-temperature environment depending on their use. However, the coatings formed on aluminum materials and aluminum alloy materials using the surface treatment agents disclosed in Patent Documents 1 and 2 have room for improvement in terms of deterioration of the corrosion resistance caused by exposure to a high-temperature environment (thermal corrosion resistance). Further, even when the surface treatment agent disclosed in Patent Document 3 is used, the thermal corrosion resistance is still not deemed to be sufficient although it is improved.

The present invention provides an aluminum material or aluminum alloy material that includes a surface treatment coating having excellent thermal corrosion resistance. Another object of the present invention is to provide a surface treatment agent that can form the surface treatment coating.

Means for Solving the Problems

The present inventors intensively studied to solve the above-described problems, and consequently discovered that an aluminum material or aluminum alloy material which has, on or over a surface thereof, a coating containing chromium, zirconium, zinc, and carbon and having characteristic infrared reflection peaks, exhibits excellent corrosion resistance as well as excellent thermal corrosion resistance, thereby completing the present invention.

That is, the present invention encompasses, for example, the following:

    • (1) An aluminum material or aluminum alloy material, including, on or over a surface thereof, a coating containing chromium, zirconium, zinc, and carbon,
    • wherein, in an infrared spectrum of the coating that is measured by a specular reflection method of Fourier transform infrared spectroscopy (FT-IR), peaks appear at 3,600 cm−1 to 3,000 cm−1 and 1,750 cm−1 to 1,700 cm−1;
    • (2) The aluminum material or aluminum alloy material according to (1), wherein, in the coating,
    • the content of chromium is in a range of 5 mg/m2 to 100 mg/m2, the content of zirconium is in a range of 2 mg/m2 to 150 mg/m2, and the content of carbon is in a range of 2 mg/m2 to 20 mg/m2, and
    • the content of zinc is 2% by atom to 60% by atom, taking a total content of chromium, zirconium, and zinc, which is measured by X-ray photoelectron spectroscopy (XPS), as 100% by atom;
    • (3) An aqueous surface treatment agent used for a surface treatment of an aluminum or aluminum alloy material, the aqueous surface treatment agent containing:
    • a chromium-containing ion (A);
    • a zirconium-containing ion (B);
    • a zinc-containing ion (C); and
    • an organic compound (D) having a hydroxy group and a carboxyl group, and
    • (4) A method of producing an aluminum material or aluminum alloy material that includes a coating, the method including the contact step of bringing the surface treatment agent according to (3) into contact with or over a surface of the aluminum material or aluminum alloy material.

Effects of the Invention

According to the present invention, the following can be provided: an aluminum material or aluminum alloy material that includes a surface treatment coating having excellent thermal corrosion resistance; and a surface treatment agent that can form the surface treatment coating.

MODE FOR CARRYING OUT THE INVENTION

The aluminum material or aluminum alloy material having a surface treatment coating according to the present embodiment, the surface treatment agent according to the present embodiment that can form the surface treatment coating, and production methods thereof will now be described in the following order.

    • (1) aluminum material or aluminum alloy material
    • (2) surface treatment coating
    • (3) surface treatment agent
    • (4) production methods

(1) Aluminum Material or Aluminum Alloy Material

The aluminum material or aluminum alloy material is not particularly limited as long as it is a metal material that contains aluminum. Particularly, an aluminum die-cast material to which it is difficult to impart corrosion resistance due to a thick surface oxide film and segregation of an alloy component is effective as a material on which the surface treatment coating of the present embodiment is to be formed. The use of the aluminum material or aluminum alloy material having the surface treatment coating is not particularly limited; however, the aluminum material or aluminum alloy material is preferably used as a component that is exposed to a high-temperature environment depending on the situation of use, such as an engine peripheral part or an ECU housing, since it is unlikely to cause deterioration of the thermal corrosion resistance. The aluminum material or aluminum alloy material having the surface treatment coating can be provided with an extended life by an improvement in the thermal corrosion resistance, and this can achieve effective use of resources.

(2) Surface Treatment Coating

The surface treatment coating of the present embodiment is formed on or over a surface of the aluminum material or aluminum alloy material, and contains chromium, zirconium, zinc, and carbon. The surface treatment coating of the present embodiment may consist of only these elements, or may contain other components. The components and the composition (contents) of the coating will now be described in detail.

(2-1) Chromium

The form of chromium contained in the surface treatment coating may be, but is not particularly limited to, metallic chromium, a chromium oxide such as hexavalent chromium oxide or trivalent chromium oxide, or a chromium compound bound to a component contained in a surface treatment agent. Chromium may be contained in any one of, or two or more of these forms. The content of chromium in the surface treatment coating is usually in a range of 5 mg/m2 to 100 mg/m2, preferably in a range of 10 mg/m2 to 50 mg/m2, more preferably in a range of 10 mg/m2 to 30 mg/m2, in terms of metallic chromium. The content of chromium in the surface treatment coating is measured using an X-ray fluorescence spectrometer.

(2-2) Zirconium

The form of zirconium contained in the surface treatment coating may be, but is not particularly limited to, metallic zirconium, zirconium oxide, or a zirconium compound bound to a component contained in a surface treatment agent. Zirconium may be contained in any one of, or two or more of these forms. The content of zirconium in the surface treatment coating is usually in a range of 2 mg/m2 to 150 mg/m2, preferably in a range of 5 mg/m2 to 100 mg/m2, more preferably in a range of 5 mg/m2 to 50 mg/m2, in terms of metallic zirconium. The content of zirconium in the surface treatment coating is measured using an X-ray fluorescence spectrometer.

(2-3) Zinc

The form of zinc contained in the surface treatment coating may be, but is not particularly limited to, metallic zinc, zinc oxide, or a zinc compound bound to a component contained in a surface treatment agent. Zinc may be contained in any one of, or two or more of these forms.

(2-4) Content Ratio of Zinc with Respect to Total Content of Chromium, Zirconium, and Zinc

Taking a total content of chromium, zirconium, and zinc that are contained in the surface treatment coating as 100% by atom, usually, the content ratio of zinc (Zn/(Cr+Zr+Zn)) is preferably in a range of 2% by atom to 60% by atom, more preferably in a range of 10% by atom to 40% by atom, still more preferably in a range of 10% by atom to 30% by atom.

The content of each component in the surface treatment coating for determination of the content ratio of zinc with respect to a total content of chromium, zirconium, and zinc (Zn/(Cr+Zr+Zn)) is measured by repeatedly performing the measurement of element amount based on sputtering and X-ray photoelectron spectroscopy (XPS) multiple times using an X-ray photoelectron spectrometer. It is noted here that the depth position in XPS is controlled with the distance at which SiO2 is sputtered by Ar ions. Specifically, sputtering is performed for 0.25 minutes (sputtering rate: 11.0 nm/min in terms of SiO2), and the sample surface is irradiated with a monochromatic Al-Kα ray in an analysis diameter of 100 μm, after which the resulting photoelectrons are measured. This process is repeated to measure the contents of chromium, zirconium, and zinc obtained at each depth in the thickness direction of the surface treatment coating. Taking a total content of these elements as 100% by atom, the content ratio of zinc (Zn/(Cr+Zr+Zn)) is calculated.

(2-5) Carbon

All or some of the carbon atoms contained in the surface treatment coating are derived from an organic compound having a hydroxy group and a carboxyl group that is blended in a surface treatment agent. The content of carbon in the surface treatment coating is usually in a range of 2 mg/m2 to 20 mg/m2, preferably in a range of 3 mg/m2 to 15 mg/m2, more preferably in a range of 4 mg/m2 to 12 mg/m2. The content of carbon in the surface treatment coating is measured using a total organic carbon analyzer.

(2-6) Peaks in Infrared Spectrum

An infrared spectrum of the surface treatment coating is obtained by measuring the surface treatment coating by a specular reflection method of Fourier transform infrared spectroscopy (FT-IR). The infrared spectrum obtained by measuring the surface treatment coating of the present embodiment has peaks in specific wavelength ranges. A peak derived from a hydroxy group appears at 3,600 cm−1 to 3,000 cm−1, and a peak derived from a carboxyl group appears at 1,750 cm−1 to 1,700 cm−1.

The infrared spectrum can be obtained using a Fourier transform infrared spectrophotometer under the following measurement conditions: measurement wave number=4,000 cm−1 to 400 cm−1, resolution=4 cm−1, and 128 scans. As a background, an aluminum or aluminum alloy material that does not have the surface treatment coating is used.

Thus far, the aluminum material or aluminum alloy material having a surface treatment coating according to the present embodiment have been described and, particularly, the thermal corrosion resistance can be improved by the features that the content of zinc in the surface treatment coating is in the above-described range, and that an infrared spectrum measured for the surface treatment coating has peaks in the above-described wavelength ranges.

(3) Surface Treatment Agent

The surface treatment agent of the present embodiment is a surface treatment agent that is used for a surface treatment of an aluminum or aluminum alloy material. The surface treatment agent can be utilized as a chemical conversion treatment agent.

The surface treatment agent contains: a chromium-containing ion (A); a zirconium-containing ion (B); a zinc-containing ion (C); and an organic compound (D) having a hydroxy group and a carboxyl group. The surface treatment agent may be prepared by blending only supply sources of these ions (A) to (C) and the organic compound (D) in an aqueous medium, or may be prepared by blending other components in addition thereto. These components, the composition (contents), and the liquid properties will now be described in detail.

(3-1) Aqueous Medium

The aqueous medium is not particularly limited as long as it is water or a mixture of water and a water-miscible organic solvent (a mixture containing not less than 50% by volume of water based on the volume of the aqueous medium). The water-miscible organic solvent is not particularly limited as long as it is miscible with water, and examples thereof include: ketone-based solvents, such as acetone and methyl ethyl ketone; amide-based solvents, such as N,N-dimethylformamide and dimethylacetamide; alcohol-based solvents, such as methanol, ethanol, and isopropanol; ether-based solvents, such as ethylene glycol monobutyl ether and ethylene glycol monohexyl ether; and pyrrolidone-based solvents, such as 1-methyl-2-pyrrolidone and 1-ethyl-2-pyrrolidone. These water-miscible organic solvents may be mixed with water singly, or in combination of two or more thereof.

(3-2) Chromium-Containing Ion (A)

In the surface treatment agent, the supply source of the chromium-containing ion (A) is not particularly limited as long as it is capable of providing the ion (A) when mixed in an aqueous medium. Examples of the supply source include chromium fluoride, chromium nitrate, chromium sulfate, and chromium phosphate. These supply sources may be used singly, or in combination of two or more thereof. The content of the ion (A) in the surface treatment agent is not particularly limited; however, it is usually in a range of 5 to 1,000 mg/L, preferably in a range of 50 to 500 mg/L, more preferably in a range of 100 to 200 mg/L, in terms of chromium-equivalent mass concentration. The ion (A) may be an ion containing a trivalent chromium.

(3-3) Zirconium-Containing Ion (B)

In the surface treatment agent, the supply source of the zirconium-containing ion (B) is not particularly limited as long as it is capable of providing the ion (B) when mixed in an aqueous medium. Examples of the supply source include zirconium sulfate, zirconium oxysulfate, zirconium ammonium sulfate, zirconium nitrate, zirconium oxynitrate, zirconium ammonium nitrate, hexafluorozirconic acid, hexafluorozirconium complex salts, zirconium acetate, zirconium lactate, zirconium tetraacetylacetonate, zirconium tributoxyacetylacetonate, tetra-n-butoxy zirconium, and tetra-n-propoxy zirconium. These supply sources may be used singly, or in combination of two or more thereof. The content of the ion (B) in the surface treatment agent is not particularly limited; however, it is usually in a range of 5 to 1,000 mg/L, preferably in a range of 30 to 300 mg/L, more preferably in a range of 70 to 200 mg/L, in terms of zirconium-equivalent mass concentration.

(3-4) Zinc-Containing Ion (C)

In the surface treatment agent, the supply source of the zinc-containing ion (C) is not particularly limited as long as it is capable of providing the ion (C) when mixed in an aqueous medium. Examples of the supply source include metallic zinc, zinc oxide, zinc carbonate, zinc nitrate, zinc chloride, zinc sulfate, zinc fluoride, zinc iodide, zinc dihydrogen phosphate, and zinc acetylacetonate. These supply sources may be used singly, or in combination of two or more thereof. The content of the ion (C) in the surface treatment agent is not particularly limited; however, it is usually in a range of 500 to 10,000 mg/L, preferably in a range of 1,000 to 5,000 mg/L, more preferably in a range of 1,500 to 2,000 mg/L, in terms of zinc-equivalent mass concentration.

(3-5) Organic Compound (D) Having Hydroxy Group and Carboxyl Group

The organic compound (D) having a hydroxy group and a carboxyl group is not particularly limited as long as it can be mixed in an aqueous medium. Examples of the organic compound (D) include organic acids, such as gluconic acid, heptogluconic acid, galactonic acid, mannonic acid, glucaric acid, galactaric acid, mannaric acid, arabinoic acid, fructuronic acid, glucuronic acid, iduronic acid, galacturonic acid, mannuronic acid, and guluronic acid, and salts of these organic acids (e.g., sodium salts and potassium salts). These organic compounds may be used singly, or in combination of two or more thereof. The amount of the organic compound having a hydroxy group and a carboxyl group in the surface treatment agent is not particularly limited; however, it is usually in a range of 2 to 2,000 mg/L, preferably in a range of 10 to 1,000 mg/L, more preferably in a range of 100 to 300 mg/L.

(3-6) Free Fluorine Ion (E)

The surface treatment agent may also contain a free fluorine ion (E). In the surface treatment agent, a supply source of the free fluorine ion (E) is not particularly limited as long as it is capable of providing the free fluorine ion (E) when mixed in an aqueous medium. Examples of the supply source include hydrofluoric acid, ammonium fluoride, chromium fluoride, hexafluorotitanic acid, hexafluorotitanium complex salts, hexafluorozirconic acid, hexafluorozirconium complex salts, magnesium fluoride, aluminum fluoride, hexafluorosilicic acid, sodium fluoride, potassium fluoride, zinc fluoride, fluoroboric acid, sodium borofluoride, and ammonium borofluoride. These supply sources may be used singly, or in combination of two or more thereof. The free fluorine ion (E) may be provided by the same compound as the above-described supply source of the ion (A), (B) and/or (C), or may be provided by a different compound. In the surface treatment agent, the fluorine-equivalent mass concentration of the free fluorine ion (E) is not particularly limited; however, it is preferably 70 to 200 mg/L, more preferably 80 to 150 mg/L.

In the present specification, the free fluorine ion concentration means a value measured at a temperature at which the surface treatment agent is brought into contact with or over a surface of an aluminum material or aluminum alloy material. The free fluorine ion concentration is a value measured in accordance with a well-known method, and can be measured using, for example, a commercially available ion counter.

In the surface treatment agent of the present embodiment, a variety of metal components and additives may be incorporated within a range that does not impair the effects of the present invention. Examples of the metal components include vanadium, molybdenum, tungsten, manganese, cerium, magnesium, calcium, cobalt, nickel, strontium, lithium, niobium, yttrium, and bismuth. Examples of the additives include formyl group-containing compounds, benzoyl group-containing compounds, amino group-containing compounds, imino group-containing compounds, cyano group-containing compounds, azo group-containing compounds, thiol group-containing compounds, sulfo group-containing compounds, nitro group-containing compounds, amidino group-containing compounds, urethane bond-containing compounds, and aromatic ring-containing compounds. These metal components and additives may be used singly, or in combination of two or more thereof. These metal components and additives are incorporated within a range that does not impair the effects of the present invention; therefore, the content thereof is at most several % by mass with respect to a total amount of the surface treatment agent.

(3-7) pH of Surface Treatment Agent

The pH of the surface treatment agent of the present embodiment is not particularly limited; however, it is preferably 3.0 to 6.0, more preferably 4.0 to 5.0. In the present specification, the pH means a value measured at a temperature at which the surface treatment agent is brought into contact with or over a surface of an aluminum material or aluminum alloy material. The pH is a value measured in accordance with a well-known method, and can be measured using, for example, a commercially available pH meter.

Thus far, the composition of the surface treatment agent of the present embodiment has been described, and another aspect of the present invention is a surface treatment agent used for a surface treatment of an aluminum or aluminum alloy material, which surface treatment agent is prepared by blending a supply source of the chromium-containing ion (A), a supply source of the zirconium-containing ion (B), a supply source of the zinc-containing ion (C), and the organic compound (D) having a hydroxy group and a carboxyl group in an aqueous medium. As each of the supply sources, one or more compounds may be used.

(4-1) Method of Producing Surface Treatment Agent

The surface treatment agent of the present embodiment can be obtained by blending with stirring appropriate amounts of a supply source of the chromium-containing ion (A), a supply source of the zirconium-containing ion (B), a supply source of the zinc-containing ion (C), and the organic compound (D) having a hydroxy group and a carboxyl group in an aqueous medium. In the production, solid supply sources may be added to the aqueous medium, or the solid supply sources may be dissolved in the aqueous medium in advance and then added as an aqueous medium solution. The pH range of the surface treatment agent is as described above, and the pH is preferably adjusted with a pH modifier, such as nitric acid, sulfuric acid, hydrofluoric acid, ammonium bicarbonate, aqueous ammonia, sodium bicarbonate, or sodium hydroxide; however, the pH modifier is not limited to these components. Such a pH modifier may be used singly, or in combination of two or more thereof.

(4-2) Method of Producing Aluminum or Aluminum Alloy Material Having Surface Treatment Coating

A method of producing an aluminum or aluminum alloy material having a surface treatment coating formed by the surface treatment agent of the present embodiment includes the step of bringing the surface treatment agent of the present embodiment into contact with or over a surface of the aluminum or aluminum alloy material. By this step, a surface treatment coating is formed on or over the surface of the aluminum or aluminum alloy material. Pretreatment steps, such as the washing step and the pickling step, may also be performed prior to the contact step. The water-washing step may be performed after each step, and the drying step may be performed after each water-washing step.

(4-3) Aluminum or Aluminum Alloy Material

The aluminum or aluminum alloy material to be treated with the surface treatment agent is not particularly limited, and the surface treatment agent is particularly effective on aluminum die-cast materials which have a thick surface oxide film and on which an alloy component is segregated. The use of the aluminum or aluminum alloy material is not particularly limited, and examples thereof include engine peripheral devices and ECU housings.

(4-4) Washing Step

In the production method of the present embodiment, the washing step of bringing a known cleaning agent into contact with or over the surface of the aluminum or aluminum alloy material is preferably performed prior to the contact step. A washing method is not particularly limited, and examples thereof include solvent degreasing and alkali degreasing.

(4-5) Pickling Step

In the production method of the present embodiment, the pickling step of bringing a known pickling agent into contact with or over the surface of the aluminum or aluminum alloy material may be performed prior to the contact step. The pickling agent is not particularly limited, and examples thereof include nitric acid and hydrofluoric acid.

(4-6) Contact Step

In the contact step of the production method of the present embodiment, the contact temperature and the contact time are not particularly limited; however, usually, the surface treatment agent is brought into contact with or over the surface of the aluminum or aluminum alloy material at 30 to 80° C., preferably at 40 to 60° C., for 10 to 1,200 seconds. After this step, if necessary, the aluminum or aluminum alloy material may be washed with water and then with deionized water, and subsequently dried. The drying temperature is not particularly limited; however, it is preferably 15 to 100° C. A method of bringing the surface treatment agent into contact with or over the surface of the aluminum or aluminum alloy material is not particularly limited, and examples thereof include an immersion method, a spray method, and a flow-coating method.

(Post-Treatment Step)

The aluminum or aluminum alloy material having a surface treatment coating, which is produced by the above-described production method, may be further post-treated with hot water, a rust inhibitor, a post-treatment agent, a pH modifier, a coupling agent, and the like. After this post-treatment, the aluminum or aluminum alloy material may be washed with water and then dried, or may be dried without being washed with water.

The aluminum or aluminum alloy material having a surface treatment coating has excellent corrosion resistance even without the coating step of coating the surface treatment coating, and maintains excellent corrosion resistance (thermal corrosion resistance) even when the surface treatment coating is exposed to a high temperature; however, the coating step may be performed as well.

The coating step is not particularly limited and can be performed by, for example, a coating method such as aqueous coating, solvent coating, powder coating, anionic electrodeposition coating, or cationic electrodeposition coating, using a known paint composition.

EXAMPLES Examples and Comparative Examples of the Present Invention Will Now be Described

It is noted here, however, that the present invention is not limited to the below-described Examples by any means.

<Aluminum Material> Aluminum Die-Cast Material (JIS ADC12) <Surface Treatment Agents>

Surface treatment agents of Examples and Comparative Examples were obtained by adding and mixing the raw materials shown in Table 1 in water such that the respective concentrations shown in Table 1 were attained. As a pH modifier, aqueous ammonia or nitric acid was used. The pH and the free fluorine ion concentration (denoted as “FF” in Table 1) were measured using a portable ion-pH meter [IM-32P (manufactured by DKK-TOA Corporation), pH electrode: GST-2729C (manufactured by DKK-TOA Corporation), ion electrode: fluoride ion composite electrode F-2021 (manufactured by DKK-TOA Corporation)].

<Treatment Method>

Specifically, the above-described aluminum die-cast material was immersed in an alkaline degreasing agent [20 g/L aqueous solution of FINE CLEANER 315E (manufactured by Nihon Parkerizing Co., Ltd.)] at 50° C. for 2 minutes, and the surface thereof was cleaned by rinsing with tap water. Subsequently, the contact step was performed on or over the surface of the aluminum die-cast material by immersing the aluminum die-cast material in each of the above-obtained surface treatment agents at the respective contact temperature shown in Table 1. Thereafter, the aluminum die-cast material was washed with running tap water (at normal temperature for 30 seconds) and then with running deionized water (at normal temperature for 30 seconds), after which the aluminum die-cast material was dried using an air blower (at normal temperature for 30 seconds), whereby aluminum die-cast materials having a surface treatment coating (test pieces 1 to 39) were each obtained.

<Measurement of Surface Treatment Coating>

For each of the aluminum die-cast materials having a surface treatment coating that were obtained by the above-described surface treatment method, the content of each component in the surface treatment coating and the infrared peaks of the surface treatment coatings were measured by the below-described respective methods. The measurement results are shown in Table 2.

<Contents of Metals>

The contents of metals (chromium and zirconium) were measured using an X-ray fluorescence spectrometer [ZSX Primus IV (manufactured by Rigaku Corporation)].

<Content Ratio of Zinc with Respect to Total Content of Chromium, Zirconium, and Zinc>

The content of each component in the surface treatment coating for determination of the content ratio of zinc with respect to a total content of chromium, zirconium, and zinc (Zn/(Cr+Zr+Zn)) was measured by repeatedly performing the measurement of element amount based on sputtering and XPS multiple times using an X-ray photoelectron spectrometer [PHI5000 VersaProbe III (manufactured by ULVAC-PHI, Inc.)]. It is noted here that the depth position in XPS was controlled with the distance at which SiO2 was sputtered by Ar ions. Specifically, sputtering was performed for 0.25 minutes (sputtering rate: 11.0 nm/min in terms of SiO2), and the sample surface was irradiated with a monochromatic Al-Kα ray in an analysis diameter of 100 μm, after which the resulting photoelectrons were measured. This process was repeated to measure the contents of chromium, zirconium, and zinc obtained at each depth in the thickness direction of the surface treatment coating. Taking a total content of these elements as 100% by atom, the content ratio of zinc (Zn/(Cr+Zr+Zn)) was calculated.

<Content of Carbon>

The content of carbon (total organic carbon adhered amount) was measured using a total organic carbon analyzer [TOC-L (manufactured by Shimadzu Corporation)].

<Infrared Peaks>

An infrared spectrum of the surface treatment coating was obtained by measuring the surface treatment coating by a specular reflection method of Fourier transform infrared spectroscopy (FT-IR). Specifically, the infrared spectrum was obtained using a Fourier transform infrared spectrophotometer [ALPHA (manufactured by Bruker AXS GmbH)] under the following measurement conditions: measurement wave number=4,000 cm−1 to 400 cm−1, resolution=4 cm−1, and 128 scans. As a background, the aluminum die-cast material that did not have a surface treatment coating was used. It was verified whether or not the thus obtained infrared spectrum had a peak in a wavelength range of 3,600 cm−1 to 3,000 cm−1 and a peak in a wavelength range of 1,750 cm−1 to 1,700 cm−1.

<Evaluation of Test Pieces>

Further, for the above-obtained test pieces, tests were conducted as described below to evaluate the corrosion resistance and the post-heating corrosion resistance (thermal corrosion resistance) of each aluminum die-cast material having a surface treatment coating. The results thereof are shown in Table 3.

<<Evaluation Methods>> <Corrosion Resistance>

The test pieces 1 to 39 were each subjected to a 360-hour neutral salt spray test (JIS Z2371:2015). After each test piece was dried, the ratio of white rust generated on the surface of each test piece was visually measured. The ratio of white rust is a ratio of the area of generated white rust with respect to the area of the observed part. The evaluation criteria were as follows. The evaluation results are shown in Table 3.

<Evaluation Criteria>

    • 5: Ratio of white rust=5% or lower
    • 4: Ratio of white rust=higher than 5% but 10% or lower
    • 3: Ratio of white rust=higher than 10% but 30% or lower
    • 2: Ratio of white rust=higher than 30% but 50% or lower
    • 1: Ratio of white rust=higher than 50%

<Thermal Corrosion Resistance>

The test pieces were each heated in an electric oven (at 150° C. for 6 hours) and then subjected to a 240-hour neutral salt spray test (JIS Z2371:2015). After each test piece was dried, the ratio of white rust generated on the surface of each test piece was visually measured. The ratio of white rust is a ratio of the area of generated white rust with respect to the area of the observed part. The evaluation criteria were as follows. The evaluation results are shown in Table 3.

<Evaluation Criteria>

    • 5: Ratio of white rust=5% or lower
    • 4: Ratio of white rust=higher than 5% but 10% or lower
    • 3: Ratio of white rust=higher than 10% but 30% or lower
    • 2: Ratio of white rust=higher than 30% but 50% or lower
    • 1: Ratio of white rust=higher than 50%

TABLE 1 Composition of the surface treatment agent Chromium Zirconium Zinc Cr-equivalent Zr-equivalent Zn-equivalent concentration concentration Supply concentration Supply source of by weight Supply source by weight source by weight Chromium (mg/L) of Zirconium (mg/L) of Zinc (mg/L) Example 1 Surface treatment Chromium(III) fluoride 100 Hexafluorozirconic 90 Zinc nitrate 1600 Agent 1 trihydrate acid hexahydrate Example 2 Surface treatment Chromium(III) nitrate 100 Hexafluorozirconic 90 Zinc nitrate 1600 Agent 2 nonahydrate acid hexahydrate Example 3 Surface treatment Chromium(III) sulfate 100 Hexafluorozirconic 90 Zinc nitrate 1600 Agent 3 acid hexahydrate Example 4 Surface treatment Chromium(III) nitrate 100 Hexafluorozirconic 90 Zinc sulfate 1600 Agent 4 nonahydrate acid heptahydrate Example 5 Surface treatment Chromium(III) nitrate 100 Hexafluorozirconic 90 Zinc chloride 1600 Agent 5 nonahydrate acid Example 6 Surface treatment Chromium(III) nitrate 100 Hexafluorozirconic 90 Zinc nitrate 1600 Agent 6 nonahydrate acid hexahydrate Example 7 Surface treatment Chromium(III) nitrate 100 Hexafluorozirconic 70 Zinc nitrate 1600 Agent 7 nonahydrate acid hexahydrate Example 8 Surface treatment Chromium(III) nitrate 100 Hexafluorozirconic 70 Zinc nitrate 1600 Agent 8 nonahydrate acid hexahydrate Example 9 Surface treatment Chromium(III) nitrate 100 Hexafluorozirconic 100 Zinc nitrate 1600 Agent 9 nonahydrate acid hexahydrate Example 10 Surface treatment Chromium(III) nitrate 5 Hexafluorozirconic 100 Zinc nitrate 1600 Agent 10 nonahydrate acid hexahydrate Example 11 Surface treatment Chromium(III) nitrate 20 Hexafluorozirconic 100 Zinc nitrate 1600 Agent 11 nonahydrate acid hexahydrate Example 12 Surface treatment Chromium(III) nitrate 300 Hexafluorozirconic 100 Zinc nitrate 1600 Agent 12 nonahydrate acid hexahydrate Example 13 Surface treatment Chromium(III) nitrate 140 Hexafluorozirconic 5 Zinc nitrate 1600 Agent 13 nonahydrate acid hexahydrate Example 14 Surface treatment Chromium(III) nitrate 140 Hexafluorozirconic 20 Zinc nitrate 1600 Agent 14 nonahydrate acid hexahydrate Example 15 Surface treatment Chromium(III) nitrate 140 Hexafluorozirconio 200 Zinc nitrate 1600 Agent 15 nonahydrate acid hexahydrate Example 16 Surface treatment Chromium(III) nitrate 140 Hexafluorozirconic 100 Zinc nitrate 500 Agent 16 nonahydrate acid hexahydrate Example 17 Surface treatment Chromium(III) nitrate 140 Hexafluorozirconic 100 Zinc nitrate 1000 Agent 17 nonahydrate acid hexahydrate Example 18 Surface treatment Chromium(III) nitrate 140 Hexafluorozirconic 100 Zinc nitrate 3000 Agent 18 nonahydrate acid hexahydrate Example 19 Surface treatment Chromium(III) nitrate 140 Hexafluorozirconic 100 Zinc nitrate 1600 Agent 19 nonahydrate acid hexahydrate Example 20 Surface treatment Chromium(III) nitrate 140 Hexafluorozirconic 100 Zinc nitrate 1600 Agent 20 nonahydrate acid hexahydrate Example 21 Surface treatment Chromium(III) nitrate 140 Hexafluorozirconic 100 Zinc nitrate 1600 Agent 21 nonahydrate acid hexahydrate Example 22 Surface treatment Chromium(III) nitrate 140 Hexafluorozirconic 100 Zinc nitrate 1300 Agent 22 nonahydrate acid hexahydrate Example 23 Surface treatment Chromium(III) nitrate 140 Hexafluorozirconic 100 Zino nitrate 2500 Agent 23 nonahydrate acid hexahydrate Example 24 Surface treatment Chromium(III) nitrate 180 Hexafluorozirconic 100 Zinc nitrate 1600 Agent 24 nonahydrate acid hexahydrate Example 25 Surface treatment Chromium(III) nitrate 180 Hexafluorozirconic 100 Zinc nitrate 1600 Agent 25 nonahydrate acid hexahydrate Example 26 Surface treatment Chromium(III) nitrate 180 Hexafluorozirconic 100 Zinc nitrate 1600 Agent 26 nonahydrate acid hexahydrate Example 27 Surface treatment Chromium(III) nitrate 180 Hexafluorozirconic 100 Zinc nitrate 1600 Agent 27 nonahydrate acid hexahydrate Example 28 Surface treatment Chromium(III) nitrate 180 Hexafluorozirconic 100 Zinc nitrate 1600 Agent 28 nonahydrate acid hexahydrate Example 29 Surface treatment Chromium(III) nitrate 180 Hexafluorozirconic 100 Zinc nitrate 1600 Agent 29 nonahydrate acid hexahydrate Example 30 Surface treatment Chromium(III) nitrate 180 Hexafluorozirconic 100 Zino nitrate 1600 Agent 30 nonahydrate acid hexahydrate Example 31 Surface treatment Chromium(III) nitrate 180 Hexafluorozirconic 100 Zinc nitrate 1600 Agent 31 nonahydrate acid hexahydrate Example 32 Surface treatment Chromium(III) nitrate 180 Hexafluorozirconic 100 Zinc nitrate 1600 Agent 32 nonahydrate acid hexahydrate Example 33 Surface treatment Chromium(III) nitrate 180 Hexafluorozirconic 100 Zinc nitrate 1600 Agent 33 nonahydrate acid hexahydrate Example 34 Surface treatment Chromium(III) nitrate 180 Hexafluorozirconic 100 Zinc nitrate 1600 Agent 34 nonahydrate acid hexahydrate Example 35 Surface treatment Chromium(III) nitrate 180 Hexafluorozirconic 100 Zinc nitrate 1600 Agent 35 nonahydrate acid hexahydrate Comparative Surface treatment — 0 Hexafluorozirconic 70 Zinc nitrate 1600 Example 1 Agent 36 acid hexahydrate Comparative Surface treatment Chromium(III) nitrate 180 — 0 Zinc nitrate 1600 Example 2 Agent 37 nonahydrate hexahydrate Comparative Surface treatment Chromium(III) nitrate 100 Hexafluorozirconic 70 — 0 Example 3 Agent 38 nonahydrate acid Comparative Surface treatment Chromium(III) nitrate 100 Hexafluorozirconic 70 Zino nitrate 1600 Example 4 Agent 39 nonahydrate acid hexahydrate Composition of the surface treatment agent Organic compound Surface treatmenr condition Concentration Contact by weight FF Temperature Type (mg/L) pH (mg/L) (° C.) Example 1 Sodium 250 4.3 90 45 gluconate Example 2 Sodium 250 4.3 90 45 gluconate Example 3 Sodium 250 4.3 90 45 gluconate Example 4 Sodium 250 4.3 90 45 gluconate Example 5 Sodium 250 4.3 90 45 gluconate Example 6 Sodium 250 4.3 90 45 heptagluconate dihydrate Example 7 Sodium 100 4.0 90 40 gluconate Example 8 Sodium 250 4.0 90 40 gluconate Example 9 Sodium 500 4.0 90 40 gluconate Example 10 Sodium 250 4.3 90 45 gluconate Example 11 Sodium 250 4.3 90 45 gluconate Example 12 Sodium 250 4.3 90 45 gluconate Example 13 Sodium 250 4.3 90 45 gluconate Example 14 Sodium 250 4.3 90 45 gluconate Example 15 Sodium 250 4.3 90 45 gluconate Example 16 Sodium 250 4.3 90 45 gluconate Example 17 Sodium 250 4.3 90 45 gluconate Example 18 Sodium 250 4.3 90 45 gluconate Example 19 Sodium 100 4.3 90 45 gluconate Example 20 Sodium 250 4.3 90 45 gluconate Example 21 Sodium 500 4.3 90 45 gluconate Example 22 Sodium 250 4.3 90 45 gluconate Example 23 Sodium 250 4.3 90 45 gluconate Example 24 Sodium 100 4.5 90 50 gluconate Example 25 Sodium 250 4.5 90 50 gluconate Example 26 Sodium 500 4.5 90 50 gluconate Example 27 Sodium 5 4.3 90 45 gluconate Example 28 Sodium 50 4.3 90 45 gluconate Example 29 Sodium 500 4.3 90 45 gluconate Example 30 Sodium 250 3.3 90 45 gluconate Example 31 Sodium 250 5.0 90 45 gluconate Example 32 Sodium 250 4.3 70 45 gluconate Example 33 Sodium 250 4.3 120 45 gluconate Example 34 Sodium 250 4.3 90 35 gluconate Example 35 Sodium 250 4.3 90 75 gluconate Comparative Sodium 100 4.3 90 45 Example 1 gluconate Comparative Sodium 100 4.3 90 45 Example 2 gluconate Comparative Sodium 100 4.3 90 45 Example 3 gluconate Comparative — 0 4.3 90 45 Example 4

TABLE 2 Content in the coating Peaks in Infrated Spectrum Chromium Zirconium Zinc※1 Carbon 3600~3000 1750~1700 (mg/m2) (mg/m2) (atom %) (mg/m2) (cm−1) (cm−1) Example 1 Test Piece 1 14 15 26 4.9 exist exist Example 2 Test Piece 2 13 17 25 5.2 exist exist Example 3 Test Piece 3 11 19 24 6.1 exist exist Example 4 Test Piece 4 13 15 27 4.9 exist exist Example 5 Test Piece 5 12 17 25 5.2 exist exist Example 6 Test Piece 6 13 17 26 5.4 exist exist Example 7 Test Piece 7 15 12 30 4 exist exist Example 8 Test Piece 8 14 16 27 4 exist exist Example 9 Test Piece 9 14 17 27 4 exist exist Example 10 Test Piece 10 7 19 30 5.2 exist exist Example 11 Test Piece 11 9 18 28 5.4 exist exist Example 12 Test Piece 12 19 14 22 4.9 exist exist Example 13 Test Piece 13 15 12 30 4.6 exist exist Example 14 Test Piece 14 14 13 29 4.8 exist exist Example 15 Test Piece 15 10 22 23 6.2 exist exist Example 16 Test Piece 16 13 15 23 5.1 exist exist Example 17 Test Piece 17 12 19 24 5.2 exist exist Example 18 Test Piece 18 13 7 35 4.9 exist exist Example 19 Test Piece 19 14 17 24 5.0 exist exist Example 20 Test Piece 20 13 17 25 5.2 exist exist Example 21 Test Piece 21 13 15 26 5.3 exist exist Example 22 Test Piece 22 9 18 13 6.0 exist exist Example 23 Test Piece 23 14 17 25 7.0 exist exist Example 24 Test Piece 24 15 12 31 3.2 exist exist Example 25 Test Piece 25 15 9 29 3.8 exist exist Example 26 Test Piece 26 15 11 29 4.6 exist exist Example 27 Test Piece 27 9 25 24 4.6 exist exist Example 28 Test Piece 28 10 21 26 4.9 exist exist Example 29 Test Piece 29 12 12 34 11.4 exist exist Example 30 Test Piece 30 6 28 11 8.2 exist exist Example 31 Test Piece 31 17 11 27 4.9 exist exist Example 32 Test Piece 32 19 19 21 5.6 exist exist Example 33 Test Piece 33 21 7 28 5.9 exist exist Example 34 Test Piece 34 13 15 27 4.9 exist exist Example 35 Test Piece 35 11 7 18 7.2 exist exist Comparative Test Piece 36 0 39 6 9.1 exist exist Example 1 Comparative Test Piece 37 18 0 34 0.3 nothing nothing Example 2 Comparative Test Piece 38 11 25 0 6.2 exist exist Example 3 Comparative Test Piece 39 16 7 26 0.5 nothing nothing Example 4 ※1Take a total content of chromium, zirconiumu, and zinc that are contained in the coating as 100% by atom.

TABLE 3 Evaluation Corrosion Thermal Corrosion Resistance Resistance Example 1 Test Piece 1 5 5 Example 2 Test Piece 2 5 5 Example 3 Test Piece 3 5 5 Example 4 Test Piece 4 5 5 Example 5 Test Piece 5 5 5 Example 6 Test Piece 6 5 5 Example 7 Test Piece 7 5 5 Example 8 Test Piece 8 5 5 Example 9 Test Piece 9 5 5 Example 10 Test Piece 10 4 4 Example 11 Test Piece 11 4 4 Example 12 Test Piece 12 4 4 Example 13 Test Piece 13 4 4 Example 14 Test Piece 14 4 4 Example 15 Test Piece 15 5 4 Example 16 Test Piece 16 4 4 Example 17 Test Piece 17 4 4 Example 18 Test Piece 18 4 4 Example 19 Test Piece 19 5 5 Example 20 Test Piece 20 5 5 Example 21 Test Piece 21 5 5 Example 22 Test Piece 22 4 4 Example 23 Test Piece 23 5 4 Example 24 Test Piece 24 5 4 Example 25 Test Piece 25 5 4 Example 26 Test Piece 26 4 4 Example 27 Test Piece 27 3 4 Example 28 Test Piece 28 3 4 Example 29 Test Piece 29 4 4 Example 30 Test Piece 30 3 3 Example 31 Test Piece 31 4 4 Example 32 Test Piece 32 4 4 Example 33 Test Piece 33 4 4 Example 34 Test Piece 34 4 4 Example 35 Test Piece 35 4 3 Comparative Test Piece 36 1 1 Example 1 Comparative Test Piece 37 2 2 Example 2 Comparative Test Piece 38 4 1 Example 3 Comparative Test Piece 39 3 2 Example 4

The present invention has been described above in detail referring to concrete Examples thereof; however, it is obvious to those skilled in the art that various modifications and changes can be made without departing from the spirit and the scope of the present invention.

Claims

1. An aluminum material or aluminum alloy material, comprising, on or over a surface thereof, a coating containing chromium, zirconium, zinc, and carbon,

wherein, in an infrared spectrum of the coating that is measured by a specular reflection method of Fourier transform infrared spectroscopy (FT-IR), peaks appear at 3,600 cm−1 to 3,000 cm−1 and 1,750 cm−1 to 1,700 cm−1.

2. The aluminum material or aluminum alloy material according to claim 1, wherein, in the coating,

the content of chromium is in a range of 5 mg/m2 to 100 mg/m2, the content of zirconium is in a range of 2 mg/m2 to 150 mg/m2, and the content of carbon is in a range of 2 mg/m2 to 20 mg/m2, and
the content of zinc is 2% by atom to 60% by atom, taking a total content of chromium, zirconium, and zinc, which is measured by X-ray photoelectron spectroscopy (XPS), as 100% by atom.

3. An aqueous surface treatment agent used for a surface treatment of an aluminum or aluminum alloy material, the aqueous surface treatment agent comprising:

a chromium-containing ion (A);
a zirconium-containing ion (B);
a zinc-containing ion (C); and
an organic compound (D) having a hydroxy group and a carboxyl group.

4. A method of producing an aluminum material or aluminum alloy material that comprises a coating, the method comprising the contact step of bringing the surface treatment agent according to claim 3 into contact with or over a surface of the aluminum material or aluminum alloy material.

Patent History
Publication number: 20260201563
Type: Application
Filed: Nov 24, 2023
Publication Date: Jul 16, 2026
Inventors: Hiroshi Shimizu (Tokyo), Yusuke Yamamoto (Tokyo), Aoi Washio (Tokyo), Keitaro Nojiri (Tokyo)
Application Number: 19/135,466
Classifications
International Classification: C23C 22/56 (20060101);