Corrosion-resistant member

Abstract

Provided is a corrosion-resistant member in which a corrosion-resistant coating film is unlikely to detach from a base material even if the corrosion-resistant member has undergone a thermal history. The corrosion-resistant member comprises: a base material (10) constituted of aluminum or an aluminum alloy; and a corrosion-resistant coating film (20) formed on a surface of the base material (10). The corrosion-resistant coating film (20) contains aluminum hydroxyfluoride AlF3-x(OH)x in which a space group belongs to R-3c, wherein x in the abovementioned chemical formula is from 0.05 to 1.00, inclusive.

Description

Technical Field

[0001] The present invention relates to a corrosion-resistant member.

Background Art

[0002] In the semiconductor manufacturing process, corrosive gases such as chlorine gas and fluorine gas may be used. Therefore, members (such as shower heads) constituting semiconductor manufacturing equipment are required to have corrosion resistance. Patent Document 1 discloses a member such as a shower head having an aluminum surface coated with a corrosion-resistant film composed of at least one of aluminum fluoride and magnesium fluoride.

[0003] Patent Document 2 discloses a film-forming material containing aluminum oxyfluoride, and it is described that a film produced by this film-forming material has high corrosion resistance against plasma using halogen-based gases such as fluorine-based gases. Patent Document 3 discloses a corrosion-resistant member in which an aluminum portion exposed on the surface of a composite containing aluminum is covered with a fluoride. This fluoride has a main crystal phase composed of aluminum fluoride hydroxide estimated to be Al2F3(OH)3 and is described as having high corrosion resistance against halogen-based corrosive gases.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the members disclosed in Patent Documents 1 to 3 had a problem that the corrosion-resistant coating was likely to peel off from the base material due to the heat history. An object of the present invention is to provide a corrosion-resistant member in which the corrosion-resistant coating is less likely to peel off from the base material even when subjected to a heat history.

Means for Solving the Problems

[0006] To solve the above problems, one aspect of the present invention is as follows [1] to [5]. [1] A base material made of aluminum or an aluminum alloy, and a corrosion-resistant coating formed on the surface of the base material, The corrosion-resistant coating contains aluminum fluoride hydroxide AlF 3-x (OH) x where x in the chemical formula is 0.05 or more and 1.00 or less, and the corrosion-resistant member.

[0007] [2] The corrosion-resistant member according to [1], wherein x in the chemical formula is 0.10 or more and 0.70 or less. [3] The corrosion-resistant member according to [1], wherein x in the chemical formula is 0.15 or more and 0.50 or less.

[0008] [4] The corrosion-resistant member according to any one of [1] to [3], wherein the half-value width of the peak with the maximum intensity obtained by analyzing the aluminum fluoride hydroxide by X-ray diffraction method is 0.50° or less. [5] The corrosion-resistant member according to any one of [1] to [4], wherein the base material is made of an aluminum alloy containing magnesium, and an intermediate layer made of magnesium fluoride is disposed between the base material and the corrosion-resistant coating.

Advantages of the Invention

[0009] In the corrosion-resistant member according to the present invention, the corrosion-resistant coating is less likely to peel off from the base material even when subjected to a heat history.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0011] An embodiment of the present invention will be described below. Note that this embodiment shows an example of the present invention, and the present invention is not limited to this embodiment. Further, various changes or improvements can be made to this embodiment, and forms with such changes or improvements can also be included in the present invention.

[0012] As shown in FIG. 1, the corrosion-resistant member according to this embodiment includes a base material 10 made of aluminum (Al) or an aluminum alloy, and a corrosion-resistant coating 20 formed on the surface of the base material 10. The corrosion-resistant coating 20 contains aluminum fluoride hydroxide AlF 3-x (OH) x wherein x in the chemical formula is 0.05 or more and 1.00 or less. Note that the corrosion-resistant coating 20 may be composed of aluminum fluoride hydroxide AlF 3-x (OH) x or may be composed of a mixture of aluminum fluoride hydroxide AlF 3-x (OH) x and other materials.

[0013] Even when the corrosion-resistant member having such a configuration is subjected to a heat history, the corrosion-resistant coating 20 is difficult to peel off from the base material 10. In particular, the corrosion-resistant member according to the present embodiment has excellent corrosion resistance against corrosive gases such as halogen gases (for example, fluorine gas (F2), chlorine gas (Cl2)) used as cleaning gases in the semiconductor manufacturing process, their plasmas, and oxygen gas (O2) used as process gases in the semiconductor manufacturing process and its plasma. Even when subjected to a heat history in these gases or their plasmas, the corrosion-resistant coating 20 is difficult to peel off from the base material 10. In addition, since the corrosion-resistant coating 20 is difficult to peel off from the base material 10 even when the corrosion-resistant member according to the present embodiment is subjected to a heat history, it also has the effect of suppressing the generation of particles due to the peeling of the corrosion-resistant coating 20.

[0014] Such a corrosion-resistant member according to the present embodiment is suitable as a member that requires corrosion resistance and heat resistance. For example, it is suitable as a member constituting a semiconductor manufacturing apparatus (particularly, a film forming apparatus using chemical vapor deposition). Specific examples include a susceptor, a shower head, and a chamber body of a film forming apparatus for forming a thin film on a wafer. If the corrosion-resistant member according to the present embodiment is used as a member constituting a semiconductor manufacturing apparatus, the generation of particles is suppressed, so that semiconductors can be manufactured with a high yield.

[0015] X in the above chemical formula can be measured by X-ray photoelectron spectroscopy (XPS). Examples of the measuring apparatus include a scanning X-ray photoelectron spectroscopic analyzer Quantera II (registered trademark) manufactured by ULVAC-PHI, Inc. As an example of the X-ray conditions, Al monochromator 100 μm, 25 W, 15 kV, and the analysis area may be 100 μm 2 It may be. Further, the electron / ion neutralization gun may be turned on, and the photoelectron extraction angle may be 45°.

[0016] In X-ray photoelectron spectroscopy, surface etching and analysis are alternately performed by argon (Ar) ion sputtering to obtain the depth profile of the corrosion-resistant film 20. The argon ion sputtering at this time is carried out under the condition that the acceleration voltage is 2 kV and the surface is etched by 9.1 nm / min of silicon dioxide (SiO2). The amount of surface etching of the corrosion-resistant film 20 is calculated based on this value.

[0017] The values obtained by X-ray photoelectron spectroscopy are quantified by the relative sensitivity coefficient method. At this time, when the amount of oxygen atoms at the depth position of 30% of the thickness of the corrosion-resistant film 20 is a (atom%) and the amount of fluorine atoms is b (atom%) based on the surface, x in the chemical formula is calculated by the calculation formula of x = 3a / (a + b).

[0018] Aluminum fluoride hydroxide AlF 3-x (OH) x The space group of can be measured by analyzing the corrosion-resistant film 20 by the grazing incidence method of X-ray diffraction. As a measuring device, for example, the X-ray diffractometer X'Pert PRO MPD manufactured by PANalytical can be mentioned.

[0019] As the target, a Cu anode can be used, as the detector, a collimator CCD can be used, and as the optical system, a parallel beam can be used respectively. The tube voltage may be 45 kV, the tube current may be 40 mA, the scan range may be 10 to 40°, the scan step size may be 0.05°, the scan speed may be 0.5° / min, and the X-ray incident angle may be 1.0°. From the peak profile obtained by X-ray diffraction, with reference to the PDF database (= Powder Diffraction File (PDF) of the Powder X-ray Database (International Centre for Diffraction Data; ICDD)), the type of space group is determined.

[0020] In the chemical formula, x needs to be 0.05 or more and 1.00 or less, preferably 0.10 or more and 0.70 or less, and more preferably 0.15 or more and 0.50 or less. By doing so, the effect that the corrosion-resistant coating 20 is less likely to peel off from the base material 10 even when subjected to a heat history becomes higher.

[0021] Further, the aluminum fluoride hydroxide AlF contained in the corrosion-resistant coating 20 3-x (OH) x is preferably such that the half-value width of the peak with the maximum intensity obtained by X-ray diffraction analysis is 0.60° or less, and more preferably 0.50° or less. By doing so, the effect that the corrosion-resistant coating 20 is less likely to peel off from the base material 10 even when subjected to a heat history in various gas atmospheres becomes higher.

[0022] The aluminum fluoride hydroxide AlF 3-x (OH) x The half-value width can be measured by analyzing the corrosion-resistant coating 20 by the grazing incidence method of X-ray diffraction, similar to the case of the space group. As the measuring device, similar to the case of the space group, for example, the X-ray diffractometer X'Pert PRO MPD manufactured by PANalytical can be mentioned. The above half-value width can be obtained by obtaining the half-value width of the peak with the maximum intensity that appears at 24 to 26° of the peak profile obtained by X-ray diffraction. Note that this peak is attributed to the plane with the Miller index (012).

[0023] Furthermore, in the corrosion-resistant member according to the present embodiment, the thickness of the corrosion-resistant coating 20 is preferably 0.1 μm or more and 50 μm or less, and more preferably 0.2 μm or more and 10 μm or less. By doing so, the corrosion resistance of the corrosion-resistant member according to the present embodiment becomes higher. The method for measuring the thickness of the corrosion-resistant coating 20 is not particularly limited, and examples include a transmission electron microscope (TEM), a scanning transmission electron microscope (STEM), a scanning electron microscope (SEM), etc.

[0024] Furthermore, in the corrosion-resistant member according to the present embodiment, the base material 10 is preferably made of an aluminum alloy containing magnesium (Mg), more preferably made of an aluminum alloy containing 0.5 mass% or more of magnesium, and even more preferably made of an aluminum alloy containing 0.7 mass% or more and 10 mass% or less of magnesium.

[0025] In that case, it is preferable that an intermediate layer (not shown in FIG. 1) made of magnesium fluoride (MgF2) is disposed between the base material 10 and the corrosion-resistant coating 20. By disposing an intermediate layer between the base material 10 and the corrosion-resistant coating 20, the effect that the corrosion-resistant coating 20 is less likely to peel from the base material 10 even when subjected to a heat history becomes higher. Further, since the base material 10 is made of an aluminum alloy containing magnesium, the strength of the corrosion-resistant member is increased.

[0026] At this time, the thickness of the intermediate layer is preferably 0.1 μm or more and 3.0 μm or less, and more preferably 0.2 μm or more and 1.0 μm or less. By doing so, the effect that the corrosion-resistant coating 20 is less likely to peel from the base material 10 even when subjected to a heat history becomes even higher. The method for measuring the thickness of the intermediate layer is the same as that for the thickness of the corrosion-resistant coating 20.

[0027] Next, a method for manufacturing the corrosion-resistant member according to the present embodiment will be described. The method for manufacturing the corrosion-resistant member according to the present embodiment is not particularly limited, but as an example, via a coating of a precursor of aluminum fluoride hydroxide AlF 3-x (OH) x a method of forming a coating of aluminum fluoride hydroxide AlF 3-x (OH) x is mentioned. According to this method, it becomes easy to uniformly generate the corrosion-resistant coating 20.

[0028] To describe in detail the manufacturing method via the precursor coating, on the surface of the base material 10 made of aluminum or an aluminum alloy, aluminum fluoride hydroxide AlF 3-x (OH) xA film of a precursor is formed, and the precursor film is heat-treated in a fluorine-containing gas to convert the precursor into aluminum fluoride hydroxide AlF 3-x (OH) x and then a corrosion-resistant film 20 composed of aluminum fluoride hydroxide AlF 3-x (OH) x is formed on the surface of the substrate 10. Examples of the method for forming the precursor film on the surface of the substrate 10 include methods such as chemical treatment, anodization, electrophoretic deposition method, and vapor deposition method.

[0029] Examples of the precursor of aluminum fluoride hydroxide AlF 3-x (OH) x include aluminum oxide (Al2O3), aluminum hydroxide (Al(OH)3), aluminum oxyhydroxide (AlO(OH)), aluminum fluoride hydroxide (such as AlF(OH)2), aluminum oxyfluoride (AlOF), and aluminum fluoride (AlF3). The precursor film may be composed of one of these compounds or two or more of them. Further, these compounds may be anhydrous or hydrated, and may be crystalline or amorphous. If the thickness of the formed precursor film is 0.1 μm or more and 50 μm or less, the thickness of the corrosion-resistant film 20 can be 0.1 μm or more and 50 μm or less.

[0030] The type of the fluorine-containing gas used when heat-treating the precursor film is not particularly limited as long as it is a gas of a compound containing fluorine, but a gas composed of at least one of fluorine gas, hydrogen fluoride (HF) gas, nitrogen trifluoride (NF3) gas, carbon tetrafluoride (CF4) gas, trifluoromethane gas (CHF3), hexafluoroethane (C2F6) gas, and hexafluorobutadiene gas (C4F6) is preferable. In addition, a mixed gas of a fluorine-containing gas and an inert gas such as nitrogen gas (N2) or argon gas may be used when heat-treating the precursor film.

[0031] The treatment temperature during the heat treatment is preferably 220°C or higher and 475°C or lower, more preferably 250°C or higher and 460°C or lower, and even more preferably 280°C or higher and 450°C or lower. The treatment time of the heat treatment is preferably 2 hours or longer and 240 hours or shorter, more preferably 3 hours or longer and 150 hours or shorter, and even more preferably 5 hours or longer and 100 hours or shorter.

[0032] If the treatment temperature during the heat treatment is 220°C or higher and the treatment time is 2 hours or longer, the x of aluminum fluoride hydroxide AlF 3-x (OH) x is likely to be 1.00 or less. Also, if the treatment temperature during the heat treatment is 475°C or lower and the treatment time is 240 hours or shorter, the x of aluminum fluoride hydroxide AlF 3-x (OH) x is likely to be 0.05 or more.

[0033] Furthermore, if the treatment temperature during the heat treatment is 300°C or higher and the treatment time is 3 hours or longer, the half-value width of the peak with the maximum intensity (i.e., the peak of the (012) plane) obtained by analyzing aluminum fluoride hydroxide AlF 3-x (OH) x by X-ray diffraction method is likely to be 0.60° or less. Furthermore, if the treatment temperature during the heat treatment is 300°C or higher and the treatment time is 3 hours or longer, the thickness of the intermediate layer composed of magnesium fluoride is likely to be 0.1 μm or more. Furthermore, if the treatment temperature during the heat treatment is 475°C or lower and the treatment time is 150 hours or shorter, the thickness of the intermediate layer composed of magnesium fluoride is likely to be 3.0 μm or less.

Examples

[0034] Examples and comparative examples are shown below to more specifically explain the present invention. 〔Example 1〕 A substrate made of aluminum alloy A5052 (JIS standard) containing 2.55% by mass of magnesium, with dimensions of 20 mm in width, 30 mm in length, and 2 mm in thickness, was formed with a corrosion-resistant coating on its surface. First, the following pretreatment was performed on the substrate.

[0035] 70 g of Screen AL-13 (manufactured by Sasaki Chemical Co., Ltd.) was dissolved in 1 L of water and the temperature was set to 50 °C to be used as a degreasing solution. The substrate was immersed in this degreasing solution for 10 minutes for degreasing and then washed with pure water. Next, 500 g of Screen AL-5000 (manufactured by Sasaki Chemical Co., Ltd.) heated to 70 °C was used as an etching solution. The degreased substrate was immersed in this etching solution for 1 minute for etching and then washed with pure water. Then, 200 g of Smart Clean (manufactured by Raiki Co., Ltd.) was dissolved in 400 g of water and the temperature was set to 25 °C to be used as a smut removal solution. The etched substrate was immersed in this smut removal solution for 30 seconds for smut removal and then washed with pure water. And the substrate after smut removal was vacuum dried to complete the pretreatment.

[0036] The substrate subjected to the above pretreatment was immersed in a Teflon (registered trademark) container containing 1.0 g of aluminum fluoride powder (manufactured by Fujifilm Wako Pure Chemical Corporation) and 99.0 g of ultrapure water. The Teflon container was covered, and further this Teflon container was placed in a SUS container (autoclave reactor) and covered. By heating this autoclave reactor at 200 °C for 10 hours, a coating of a precursor of aluminum fluoride hydroxide AlF 3-x (OH) x was coated on the surface of the substrate subjected to the above pretreatment.

[0037] The substrate whose surface was covered with the precursor coating was heated to 400 °C in a mixed gas atmosphere of 20% by volume of fluorine gas and 80% by volume of nitrogen gas and heat-treated for 10 hours. By this heat treatment, the precursor was aluminum fluoride hydroxide AlF 3-x (OH) xIt changed to form a corrosion-resistant film. In this heat treatment, since magnesium contained in the base material diffused to the surface of the base material, a film (intermediate layer) composed of magnesium fluoride was formed between the corrosion-resistant film and the base material. By such treatment, a corrosion-resistant member having a corrosion-resistant film on the surface of the base material was obtained.

[0038] As a result of analyzing the corrosion-resistant film by X-ray photoelectron spectroscopy (XPS), aluminum fluoride hydroxide AlF 3-x (OH) x The x of was 0.84. Further, as a result of analyzing the corrosion-resistant film by the grazing incidence method of X-ray diffraction, aluminum fluoride hydroxide AlF 3-x (OH) x had a space group of R-3c and a half-value width of the peak with the maximum intensity of 0.44°.

[0039] A heating test was conducted on the obtained corrosion-resistant member of Example 1 to evaluate the peeling state of the corrosion-resistant film. The conditions of the heating test were such that the temperature was raised to 350°C in 1 hour in a nitrogen gas atmosphere, held at 350°C for 300 min, and then cooled to room temperature in 1 hour, and this process was taken as one cycle, and this was repeated 10 cycles.

[0040] After the heating test was completed, the corrosion-resistant film of the corrosion-resistant member was observed with a scanning electron microscope to evaluate the degree of peeling of the corrosion-resistant film. The results are shown in Table 1. In Table 1, when the area of the peeled portion of the corrosion-resistant film was less than 1% of the total area of the corrosion-resistant film, it was indicated as A, when it was 1% or more and less than 5%, it was indicated as B, when it was 5% or more and less than 30%, it was indicated as C, and when it was 30% or more, it was indicated as D.

[0041] In addition, a corrosion test was conducted on the obtained corrosion-resistant member of Example 1, and the state of peeling of the corrosion-resistant film was evaluated. The corrosion test involves subjecting one corrosion-resistant member to heat treatment continuously in the order of a chlorine gas atmosphere, a fluorine gas atmosphere, and an oxygen gas atmosphere as one cycle, and repeating this 5 cycles. Each of the above gas atmospheres is a mixed gas atmosphere of 20% by volume of chlorine gas, fluorine gas, or oxygen gas and 80% by volume of nitrogen gas. Also, the heat treatment temperature is 250 °C and the time is 300 min.

[0042] After the corrosion test was completed, the corrosion-resistant film of the corrosion-resistant member was observed with a scanning electron microscope to evaluate the degree of crack generation. 20 fields of view were confirmed at a magnification of 500 times, and the number of fields of view in which cracks occurred was counted. The results are shown in Table 1. In Table 1, when the number of fields of view in which cracks occurred was 0, it is indicated as A; when it was 1 or more and less than 5 fields of view, it is indicated as B; when it was 5 or more and less than 10 fields of view, it is indicated as C; and when it was 10 or more fields of view, it is indicated as D.

[0043]

Table 1

[0044] 〔Example 2〕 A corrosion-resistant member was produced in the same manner as in Example 1, except that the heat treatment conditions for heating a substrate whose surface was covered with a precursor film in a mixed gas atmosphere of 20% by volume of fluorine gas and 80% by volume of nitrogen gas were a temperature of 400 °C and a treatment time of 20 hours.

[0045] As a result of analyzing the corrosion-resistant film by X-ray photoelectron spectroscopy, the x in aluminum fluoride hydroxide AlF 3-x (OH) x constituting the corrosion-resistant film was 0.17. Also, as a result of analyzing the corrosion-resistant film by the grazing incidence method of X-ray diffraction, the space group of aluminum fluoride hydroxide AlF 3-x (OH) x constituting the corrosion-resistant film was R-3c, and the full width at half maximum of the peak with the maximum intensity was 0.47°. The X-ray diffraction pattern at this time is shown in Figure 2. A heat test was conducted on the obtained corrosion-resistant member of Example 2, and the peeling state of the corrosion-resistant film was evaluated. Also, a corrosion test was conducted, and the crack state of the corrosion-resistant film was evaluated. The results are shown in Table 1.

[0046] [Example 3] A corrosion-resistant member was produced in the same manner as in Example 1, except that the heat treatment conditions for heating the substrate whose surface was covered with the precursor film in a mixed gas atmosphere of 20% by volume of fluorine gas and 80% by volume of nitrogen gas were a temperature of 430 °C and a treatment time of 20 hours.

[0047] As a result of analyzing the corrosion-resistant film by X-ray photoelectron spectroscopy, x of aluminum fluoride hydroxide AlF 3-x (OH) x constituting the corrosion-resistant film was 0.12. Also, as a result of analyzing the corrosion-resistant film by the grazing incidence method of X-ray diffraction, the space group of aluminum fluoride hydroxide AlF 3-x (OH) x constituting the corrosion-resistant film was R-3c, and the half-value width of the peak with the maximum intensity was 0.46°. A heat test was conducted on the obtained corrosion-resistant member of Example 3, and the peeling state of the corrosion-resistant film was evaluated. Also, a corrosion test was conducted, and the crack state of the corrosion-resistant film was evaluated. The results are shown in Table 1.

[0048] [Example 4] A corrosion-resistant member was produced in the same manner as in Example 1, except that the heat treatment conditions for heating the substrate whose surface was covered with the precursor film in a mixed gas atmosphere of 20% by volume of fluorine gas and 80% by volume of nitrogen gas were a temperature of 400 °C and a treatment time of 12 hours.

[0049] As a result of analyzing the corrosion-resistant film by X-ray photoelectron spectroscopy, x of aluminum fluoride hydroxide AlF 3-x (OH) x constituting the corrosion-resistant film was 0.68. Also, as a result of analyzing the corrosion-resistant film by the grazing incidence method of X-ray diffraction, the space group of aluminum fluoride hydroxide AlF 3-x (OH) x constituting the corrosion-resistant film was R-3c, and the half-value width of the peak with the maximum intensity was 0.42°. A heat test was conducted on the obtained corrosion-resistant member of Example 4, and the state of peeling of the corrosion-resistant film was evaluated. Further, a corrosion test was conducted to evaluate the state of cracks in the corrosion-resistant film. The results are shown in Table 1.

[0050] [Example 5] A corrosion-resistant member was produced in the same manner as in Example 1, except that the heat treatment conditions for heating a substrate whose surface was covered with a precursor film in a mixed gas atmosphere of 20% by volume of fluorine gas and 80% by volume of nitrogen gas were a temperature of 400 °C and a treatment time of 15 hours.

[0051] As a result of analyzing the corrosion-resistant film by X-ray photoelectron spectroscopy, x of aluminum fluoride hydroxide AlF 3-x (OH) x constituting the corrosion-resistant film was 0.47. Further, as a result of analyzing the corrosion-resistant film by the grazing incidence method of X-ray diffraction, the space group of aluminum fluoride hydroxide AlF 3-x (OH) x constituting the corrosion-resistant film was R-3c, and the half-value width of the peak with the maximum intensity was 0.47°. A heat test was conducted on the obtained corrosion-resistant member of Example 5, and the state of peeling of the corrosion-resistant film was evaluated. Further, a corrosion test was conducted to evaluate the state of cracks in the corrosion-resistant film. The results are shown in Table 1.

[0052] [Example 6] A corrosion-resistant member was produced in the same manner as in Example 1, except that a substrate made of pure aluminum (JIS standard: A1080) containing no magnesium was used instead of the substrate made of aluminum alloy A5052 containing 2.55% by mass of magnesium.

[0053] As a result of analyzing the corrosion-resistant film by X-ray photoelectron spectroscopy, x of aluminum fluoride hydroxide AlF 3-x (OH) x constituting the corrosion-resistant film was 0.20. Further, as a result of analyzing the corrosion-resistant film by the grazing incidence method of X-ray diffraction, the space group of aluminum fluoride hydroxide AlF 3-x (OH) xThe space group is R-3c, and the full width at half maximum of the peak with the maximum intensity was 0.47°. A heat test was conducted on the corrosion-resistant member of Example 6 obtained, and the state of peeling of the corrosion-resistant coating was evaluated. Further, a corrosion test was conducted, and the state of cracks in the corrosion-resistant coating was evaluated. The results are shown in Table 1.

[0054] [Comparative Example 1] A corrosion-resistant member was produced in the same manner as in Example 1, except that the conditions of the heat treatment for heating the substrate whose surface was covered with the precursor coating in a mixed gas atmosphere of 20% by volume of fluorine gas and 80% by volume of nitrogen gas were a temperature of 400°C and a treatment time of 1 hour.

[0055] As a result of analyzing the corrosion-resistant coating by X-ray photoelectron spectroscopy, for aluminum fluoride hydroxide AlF 3-x (OH) x the x was 1.13. Further, as a result of analyzing the corrosion-resistant coating by the grazing incidence method of X-ray diffraction, for aluminum fluoride hydroxide AlF 3-x (OH) x the space group was R-3c, and the full width at half maximum of the peak with the maximum intensity was 0.72°. A heat test was conducted on the corrosion-resistant member of Comparative Example 1 obtained, and the state of peeling of the corrosion-resistant coating was evaluated. Further, a corrosion test was conducted, and the state of cracks in the corrosion-resistant coating was evaluated. The results are shown in Table 1.

[0056] [Comparative Example 2] A corrosion-resistant member was produced in the same manner as in Example 1, except that the conditions of the heat treatment for heating the substrate whose surface was covered with the precursor coating in a mixed gas atmosphere of 20% by volume of fluorine gas and 80% by volume of nitrogen gas were a temperature of 200°C and a treatment time of 20 hours.

[0057] As a result of analyzing the corrosion-resistant coating by X-ray photoelectron spectroscopy, for aluminum fluoride hydroxide AlF 3-x (OH) x the x was 1.61. Further, as a result of analyzing the corrosion-resistant coating by the grazing incidence method of X-ray diffraction, for aluminum fluoride hydroxide AlF 3-x (OH)x The space group is Fd-3m, and it was difficult to determine the full width at half maximum of the peak with the highest intensity. The X-ray diffraction pattern at this time is shown in Fig. 3. A heat test was conducted on the obtained corrosion-resistant member of Comparative Example 2 to evaluate the state of peeling of the corrosion-resistant film. In addition, a corrosion test was conducted to evaluate the state of cracks in the corrosion-resistant film. The results are shown in Table 1.

[0058] 〔Comparative Example 3〕 A corrosion-resistant member was produced in the same manner as in Example 1, except that the heat treatment conditions for heating a substrate whose surface was covered with a precursor film in a mixed gas atmosphere of 20% by volume of fluorine gas and 80% by volume of nitrogen gas were set to a temperature of 480°C and a treatment time of 300 hours.

[0059] As a result of analyzing the corrosion-resistant film by X-ray photoelectron spectroscopy, aluminum fluoride hydroxide AlF 3-x (OH) x had an x value of 0.04. Further, as a result of analyzing the corrosion-resistant film by the grazing incidence method of X-ray diffraction, aluminum fluoride hydroxide AlF 3-x (OH) x had a space group of R-3c, and the full width at half maximum of the peak with the highest intensity was 0.30°. A heat test was conducted on the obtained corrosion-resistant member of Comparative Example 3 to evaluate the state of peeling of the corrosion-resistant film. In addition, a corrosion test was conducted to evaluate the state of cracks in the corrosion-resistant film. The results are shown in Table 1.

[0060] 〔Comparative Example 4〕 A corrosion-resistant member was produced in the same manner as in Example 1, except that the substrate whose surface was covered with a precursor film was not subjected to heat treatment. As a result of analyzing the corrosion-resistant film by X-ray photoelectron spectroscopy, aluminum fluoride hydroxide AlF 3-x (OH) x had an x value of 2.19. Further, as a result of analyzing the corrosion-resistant film by the grazing incidence method of X-ray diffraction, aluminum fluoride hydroxide AlF 3-x (OH) x was amorphous. A heat test was conducted on the obtained corrosion-resistant member of Comparative Example 4, and the state of peeling of the corrosion-resistant film was evaluated. Also, a corrosion test was conducted to evaluate the state of cracks in the corrosion-resistant film. The results are shown in Table 1.

[0061] As can be seen from Table 1, for the corrosion-resistant members of Examples 1 to 6, peeling and cracking of the corrosion-resistant film hardly occurred even when they received a heat history in a nitrogen gas atmosphere and a corrosive gas atmosphere. On the other hand, for the corrosion-resistant members of Comparative Examples 1 to 4, peeling and cracking of the corrosion-resistant film occurred when they received a heat history in a nitrogen gas atmosphere and a corrosive gas atmosphere. Aluminum fluoride hydroxide AlF 3-x (OH) x If the space group of is assigned to R-3c and x in the chemical formula is 0.05 or more, it is considered that the corrosion-resistant film has sufficient strength against the stress generated by thermal expansion or thermal contraction of the base material during heating and cooling.

[0062] Also, aluminum fluoride hydroxide AlF 3-x (OH) x If the space group of is assigned to R-3c and x in the chemical formula is 1.00 or less, even if heat treatment is performed in a chlorine gas atmosphere, a fluorine gas atmosphere, or an oxygen gas atmosphere, the composition of aluminum fluoride hydroxide AlF 3-x (OH) x is less likely to change. As a result, it is considered that volume expansion and volume contraction of the corrosion-resistant film due to heating and cooling are less likely to occur. As a result, it is considered that cracks in the corrosion-resistant film are less likely to occur.

Explanation of Symbols

[0063] 10 ··· Base material 20 ··· Corrosion-resistant film

Claims

1. A base material made of aluminum or an aluminum alloy, and a corrosion-resistant film formed on the surface of the base material. The corrosion-resistant film is an aluminum fluoride hydroxide AlF 3-x (OH) x that belongs to the space group R-3c and is contained in the corrosion-resistant member, where x in the chemical formula is 0.05 or more and 1.00 or less.

2. The corrosion-resistant member according to Claim 1, wherein x in the chemical formula is 0.10 or more and 0.70 or less.

3. The corrosion-resistant member according to Claim 1, wherein x in the chemical formula is 0.15 or more and 0.50 or less.

4. The corrosion-resistant member according to any one of Claims 1 to 3, wherein the half-value width of the peak with the maximum intensity obtained by analyzing the aluminum fluoride hydroxide by X-ray diffraction is 0.50° or less.

5. The corrosion-resistant member according to any one of Claims 1 to 4, wherein the base material is made of an aluminum alloy containing magnesium, and an intermediate layer made of magnesium fluoride is disposed between the base material and the corrosion-resistant film.

Images