WO2019225641A1

WO2019225641A1 - Hydrogen permeable membrane and method for producing same

Info

Publication number: WO2019225641A1
Application number: PCT/JP2019/020255
Authority: WO
Inventors: 之貴加藤; 前田　哲彦; 成輝遠藤; 聡八重樫; 義智古川; 憲和出澤
Original assignee: 国立大学法人東京工業大学; 国立研究開発法人産業技術総合研究所; 株式会社山王
Priority date: 2018-05-22
Filing date: 2019-05-22
Publication date: 2019-11-28
Also published as: TWI716879B; JP6695929B2; JP2019202259A; TW202003100A

Abstract

This hydrogen permeable membrane comprises an alloy film which contains Pd and Cu. This alloy film is an electrolytic plating film and has a BCC structure; and the Pd:Cu ratio (atomic ratio) in this alloy film is from 4:6 to 6:4.

Description

Hydrogen permeable membrane and method for producing the same

The present invention relates to a hydrogen permeable membrane and a manufacturing method thereof.

As a material for obtaining high-purity hydrogen, a hydrogen permeable membrane that selectively transmits hydrogen has been proposed. A film containing a Pd alloy film is known as a hydrogen permeable film. A PdCu alloy film is known as a Pd alloy film.

Regarding a PdCu alloy membrane for a hydrogen permeable membrane, Patent Document 1 (Japanese Patent Laid-Open No. 2008-81765) discloses a palladium alloy plating solution containing a specific palladium complex and a hydrogen separation membrane formed by the plating solution. ing. Patent Document 1 describes that, as a specific example, an alloy film is formed using a plating solution containing palladium chloride, copper nitrate, asparagine, dipotassium citrate, and dipotassium hydrogen phosphate.

In Non-Patent Document 1 (Creation of Electrolytic PdCu Alloy Plating Film for Hydrogen Permeation Membrane, Surface Technology Association, Abstract of 125th Lecture Meeting, page 141), after depositing electrolytic PdCu plating film on SUS304, PdCu The point where the film was peeled off, the obtained PdCu film was a film of Pd63 wt% -Cu 37 wt%, a value very close to Pd60 wt% -Cu 40 wt%, which is an alloy ratio having hydrogen permeability, and PdCu before and after heat treatment When the crystallinity of the film was confirmed, only the α phase was confirmed before the heat treatment, but the β phase was formed after the heat treatment, and the hydrogen permeability of the PdCu alloy film is a mixture of the α phase and the β phase. Since the effect is acquired by this, it is described that the obtained PdCu alloy film is considered to have a function as a hydrogen permeable film.

However, in both Patent Document 1 and Non-Patent Document 1, there is no description as to whether or not the obtained PdCu alloy film actually functioned as a hydrogen permeable film. And according to the knowledge of the present inventors, even if a PdCu alloy film is formed by electrolytic plating and a β phase (body-centered cubic phase) is formed by performing heat treatment as described in Non-Patent Document 1, By itself, sufficient hydrogen permeation performance as a hydrogen permeable membrane cannot be obtained.

Therefore, an object of the present invention is to provide a hydrogen permeable film using a PdCu alloy film having sufficient hydrogen permeable performance, and a method for manufacturing the same.

In order to solve the above problems, the present invention includes the following matters.
[1] including an alloy film containing Pd and Cu,
The alloy film is
Electrolytic plating film,
Has a BCC structure,
The Pd: Cu ratio (atomic ratio) in the alloy film is 6: 4 to 4: 6.
Hydrogen permeable membrane.
[2] The hydrogen permeable membrane according to [1], wherein the alloy film has a thickness of 1 to 100 μm.
[3] producing an alloy film containing Pd and Cu;
Changing at least part of the crystal structure of the alloy film to a BCC structure in the presence of non-oxygen;
After the step of changing to the BCC structure, the step of treating the alloy film with oxygen under heating conditions;
After the step of treating with oxygen, the step of treating the alloy film with a reducing gas,
A method for producing a hydrogen permeable membrane.
[4] The manufacturing method according to [3], wherein the step of manufacturing the alloy film includes a step of forming the alloy film by electrolytic plating.
[5] The manufacturing method according to [3] or [4], wherein the step of changing to the BCC structure includes a step of heat-treating the alloy film in a reduced pressure state.
[6] The production method according to any one of [3] to [5], wherein the reducing gas contains hydrogen.
[7] Further, after the step of treating with oxygen, a step of reducing the environment containing the alloy film to a reduced pressure state,
The step of treating with the reducing gas includes the step of introducing the reducing gas into an environment including the alloy film after the step of reducing the pressure, and any one of the above [3] to [6] The manufacturing method described in 1.
[8] The production method according to any one of [3] to [7], wherein the treatment with the reducing gas is performed under heating conditions.
[9] Furthermore,
After the step of treating with the reducing gas, the step of depressurizing the environment including the alloy film and re-depressing the environment,
After the step of reducing the pressure again, cooling the alloy film;
After the cooling step, returning the environment containing the alloy film to atmospheric pressure;
The manufacturing method in any one of said [3] thru | or [8] provided.

According to the present invention, there are provided a hydrogen permeable membrane using a PdCu alloy membrane having sufficient hydrogen permeability and a method for producing the same.

FIG. 1 shows an SEM photograph of the alloy film. FIG. 2 shows an X-ray diffraction intensity spectrum of the alloy film. FIG. 3 shows the indentation test result in the alloy film.

1: Method for Producing Hydrogen Permeable Membrane A method for producing a hydrogen permeable membrane according to an embodiment of the present invention includes a step of producing an alloy film containing Pd and Cu (step S1), and at least part of the crystal structure of the alloy film. A step of changing the alloy film to a BCC (body-centered cubic) structure in the absence of oxygen (step S2) and a step of changing to a BCC structure after the alloy film is treated with oxygen under heating conditions (step S2) After step S3) and the step of treating with oxygen, a step of treating the alloy film with a reducing gas (step S4) is provided.

In general, it is considered that a part of the crystal structure needs to have a BCC structure in order to improve the hydrogen permeation performance of the Pd alloy film. However, in the case of a PdCu alloy film, sufficient hydrogen permeation performance cannot be obtained by simply forming part of the crystal structure into the BCC structure. On the other hand, according to the present invention, after changing a part of the crystal structure to the BCC structure in the absence of oxygen, the alloy film is treated with oxygen under heating conditions, and further treated with a reducing gas. Thus, the hydrogen permeation performance of the PdCu alloy film can be enhanced.
Below, each step is described in detail.

Step 1: Formation of alloy film An alloy film containing Pd and Cu is prepared. In this embodiment, an alloy film is produced by electrolytic plating using a PdCu plating solution.
That is, first, a PdCu plating solution is prepared.
As the PdCu plating solution, for example, a plating solution containing a palladium ion supply source such as dichlorotetraammine palladium, a copper ion supply source such as copper sulfate, and an additive such as polyphosphate can be used.

Next, using the prepared PdCu plating solution, an alloy film containing Pd and Cu is deposited on the conductive substrate by electrolytic plating.
The bath temperature at the time of plating is, for example, 20 to 80 ° C., preferably 30 to 70 ° C., more preferably 40 to 60 ° C.
The current density is, for example, 0.5 to 3.0 A / dm ² , preferably 1.0 to 2.0 A / dm ² .
The thickness of the alloy film is, for example, 1 to 100 μm, preferably 3 to 30 μm, more preferably 5 to 20 μm.
Electrolytic plating is performed under conditions such that the Pd: Cu ratio (atomic ratio) of the obtained alloy film is 4: 6 to 6: 4, preferably 4.5: 5.5 to 5.5: 4.5. To implement.
In addition, when a material having low adhesion to the alloy film (for example, SUS304) is used as the base material, the alloy film can be peeled from the base material after the alloy film is formed. As a result, the alloy film can be used alone as a hydrogen permeable film.
However, depending on the application, a laminate of the base material and the alloy film may be used as the hydrogen separation membrane without peeling the alloy film from the base material.

Step 2: Conversion of Crystal Structure The alloy film formed in step S1 has a normal FCC (face-centered cubic) structure. Therefore, at least a part of the crystal structure of the alloy film is changed to a BCC structure in the absence of oxygen. Specifically, the alloy film is heat-treated in a reduced pressure state using a high vacuum electric furnace. By performing heat treatment in a reduced pressure state, at least part of the crystal structure of the alloy film can be changed to a BCC structure.
The heat treatment temperature at this time is, for example, preferably 300 ° C. or higher, more preferably 400 ° C. or higher. Moreover, the upper limit of heat processing temperature is 600 degrees C or less, for example, Preferably it is 500 degrees C or less.
The heat treatment time is, for example, 10 minutes to 10 hours, preferably 20 minutes to 5 hours, more preferably 30 minutes to 3 hours.
In the present specification, the reduced pressure state means, for example, a state of 100 Pa or less, preferably 50 Pa or less, more preferably 10 Pa or less.

Step 3: Oxygen treatment Subsequently, the alloy film is treated with oxygen under heating conditions.
Specifically, an alloy film is disposed under the same temperature and pressure conditions as in step S2, and an oxygen-containing gas (preferably air) is introduced into the environment including the alloy film, that is, a high vacuum electric furnace. Oxygen is introduced, for example, so that the pressure returns to atmospheric pressure.

Step 4: Treatment with reducing gas Subsequently, the environment containing the alloy film is reduced in pressure again while maintaining the heating state, and the pressure is reduced.
Next, a reducing gas is introduced into the environment including the alloy film. The reducing gas is introduced, for example, until the pressure returns to atmospheric pressure.
As the reducing gas, for example, hydrogen, green gas (3% hydrogen + argon) or the like can be used, and preferably hydrogen is used.

Step S5: Cooling After cooling the alloy film, it is taken out from the high vacuum electric furnace. Thereby, the hydrogen permeable film which concerns on this embodiment can be obtained.
The PdCu alloy film has the property of occluding hydrogen under low temperature conditions (about 300 ° C. or lower). Therefore, hydrogen may be occluded in the alloy film when cooling is simply performed after step S4. When hydrogen is occluded, the film may become hard and brittle. In order to prevent hydrogen from being occluded in the alloy film, the high vacuum electric furnace is preferably depressurized again before being cooled to a depressurized state. Then, after cooling in a reduced pressure state, the pressure is returned to atmospheric pressure. Thereafter, the alloy film is taken out. By using such a procedure, occlusion of hydrogen during cooling can be prevented.

2: Hydrogen permeable membrane The hydrogen permeable membrane which concerns on this embodiment has an alloy film obtained by the above-mentioned method. This alloy film may be used alone as a hydrogen permeable film, or the alloy film may be used as a hydrogen permeable film in combination with other materials.
The alloy film obtained by the above method has a BCC structure and a Pd: Cu ratio (atomic ratio) of 4: 6 to 6: 4.
Whether or not the alloy film has a BCC structure can be confirmed by, for example, X-ray diffraction. Specifically, when the BCC structure exists, a peak exists at a diffraction angle 2θ = 43 ± 0.5 in the X-ray diffraction using CuKα rays. On the other hand, when the FCC structure is present, a peak is present at the diffraction angle 2θ = 42 ± 0.5 in the X-ray diffraction using the CuKα ray.
In the above alloy film, preferably, in the X-ray diffraction of the hydrogen permeable film using CuKα rays, the peak intensity of the peak appearing at the diffraction angle 2θ = 43 ± 0.5 is the diffraction angle 2θ = 42 ± 0. It is larger than the peak intensity of the peak appearing at position 5.

As described above, according to the present embodiment, after the crystal structure of the alloy film is converted (step S2), the oxygen treatment under heating conditions (step S3) and the treatment with the reducing gas (step S4) are performed. By carrying out, a PdCu alloy film having high hydrogen permeation performance can be obtained.
According to this embodiment, an alloy film having a hydrogen permeation performance of, for example, 3 to 20 mL / min / cm ² , preferably 5 to 20 mL / min / cm ² can be obtained. The hydrogen permeation performance here refers to a value measured at 450 ° C. and a differential pressure of 1 atm.

In the present embodiment, an example in which an alloy film is produced by electrolytic plating in Step 1 (production of an alloy film) has been described. However, even when an alloy film is produced by rolling instead of electrolytic plating, high hydrogen permeation performance can be obtained by performing the processing of steps S2 to S4.
However, it is preferable that the alloy film used for the hydrogen permeable film according to the present embodiment is an electrolytic plating film. The hydrogen permeation performance depends on the film thickness of the hydrogen permeable membrane. The thinner the film thickness, the higher the hydrogen permeation performance can be obtained. When the PdCu plating solution according to this embodiment is used, it becomes easier to stably form a thin film as compared with the rolling method. Further, when the PdCu plating solution according to the present embodiment is used, an alloy film having a dense and fine crystal structure can be obtained as compared with the rolling method, and as a result, an alloy film having excellent durability can be obtained. Can do.
Whether or not it is an electrolytic plating film can be confirmed, for example, by observing a SEM photograph of a cross section of the alloy film. That is, in the case of an electrolytic plating film, the size of crystal grains observed in the cross section is smaller than that of a film obtained by a rolling method or the like. For example, when the cross section of the alloy film is observed by a SEM photograph at a magnification of 20,000, if the perimeter of the maximum crystal grain within a 5 μm × 5 μm visual field is 4 μm or less, the alloy film is an electrolytic plating film. Conceivable. In the case of a film obtained by a rolling method or the like, the “peripheral length of the maximum crystal grains” usually exceeds 4 μm.

In the present embodiment, the example in which the crystal structure is changed to the BCC structure by performing the heat treatment in the reduced pressure state in Step S2 has been described. However, in the presence of non-oxygen, it is not always necessary to be in a reduced pressure state. For example, even if heat treatment is performed in the presence of a reducing gas (for example, argon and 3% hydrogen), the crystal structure is changed to a BCC structure. be able to.

[Experimental example]
Subsequently, in order to describe the present invention in more detail, an experimental example performed by the applicant will be described.

[Examination of hydrogen permeation performance]
Example 1
Step S1: Formation of an alloy film A PdCu plating solution was prepared. As the PdCu plating solution, a plating solution containing dichlorotetraamminepalladium (Pd concentration 8 g / L), copper sulfate (Cu concentration 3 g / L), and polyphosphate was prepared.
SUS304 was prepared as a base material. On the prepared base material, electrolytic plating was performed using the prepared PdCu plating solution to deposit a PdCu alloy film. After deposition, the PdCu alloy film was peeled from the substrate.
The conditions for electrolytic plating were as follows.
Bath temperature: 50 ° C
Current density: 1.5 A / dm ²
When the Pd: Cu atomic ratio of the obtained alloy film was measured by EPMA (Electron Probe Micro Analyzer), it was 5: 5.
The film thickness of the alloy film was 10 μm.

Step S2: Heat treatment under reduced pressure Next, the obtained alloy film was placed in a high vacuum electric furnace. The alloy film was heated by reducing the pressure inside the furnace. The heating temperature was 450 ° C. and the heating time was 1 hour.
Subsequently, after cooling to room temperature, the pressure was returned to atmospheric pressure, and the alloy film was taken out from the high vacuum electric furnace.

Step S3: Oxygen Treatment at High Temperature Next, the alloy film was set in a hydrogen permeation measuring device. The environment of the alloy film was again reduced. The alloy film was heated to 450 ° C. And air was introduce | transduced in the hydrogen-permeation amount measuring apparatus, and the pressure was returned to atmospheric pressure. That is, oxygen treatment was performed at a high temperature.
Step S4: Treatment with hydrogen gas (hydrogen permeation test)
Next, the inside of the hydrogen permeation amount measuring apparatus was again evacuated while maintaining the heating state. After reducing the pressure, hydrogen was introduced into the hydrogen permeation measuring device, and the pressure was returned to atmospheric pressure.
At this time, a hydrogen permeation test was performed while maintaining the heating state, and the hydrogen permeation performance of the alloy film was measured. The hydrogen permeation test was performed according to the following procedure. In the hydrogen permeation amount measuring apparatus, an alloy film was previously arranged so as to separate the primary side space and the secondary side space. Hydrogen was supplied to the primary space so that the differential pressure between the primary space and the secondary space was 1 atm. Then, the amount of hydrogen flowing from the primary side space to the secondary side space via the alloy film was measured.

(Comparative Example 1)
In the same manner as in Example 1, an alloy film was formed on the substrate using a PdCu plating solution.
However, the formed alloy film was directly put into the hydrogen permeation amount measuring apparatus without performing the processes after the heat treatment in the reduced pressure state (Steps S2 and S3). After the inside of the hydrogen permeation measuring apparatus was in a reduced pressure state, a hydrogen permeation test was performed while introducing hydrogen into the apparatus at room temperature to measure hydrogen permeation performance (step S4).

(Comparative Example 2)
By the same method as in Example 1, an alloy film was formed on the substrate using a PdCu plating solution (step S1). The obtained alloy film was put into a high vacuum electric furnace in the same manner as in Example 1 and heat-treated in a reduced pressure state (step S2). However, unlike Example 1, the hydrogen permeation test (Step S4) was performed without performing the oxygen treatment (Step S3) in a high temperature state. That is, after step S2, the alloy film taken out from the high-vacuum electric furnace is set in a hydrogen permeation measuring device, the inside of the device is put under reduced pressure, heated to 450 ° C., hydrogen is introduced into the device, and hydrogen permeation is performed. Tests were conducted to measure hydrogen permeation performance.

(Example 2)
A PdCu alloy film (film thickness 10 μm) prepared by a rolling method was prepared. The prepared PdCu alloy film was subjected to the same treatment as in Example 1 (Steps S1 to S4), and a hydrogen permeation test was conducted.

(Comparative Example 3)
As in Example 2, a PdCu alloy film (film thickness 10 μm) prepared by a rolling method was prepared. However, as in Comparative Example 1, a hydrogen permeation test was performed at room temperature and hydrogen permeation performance was measured without performing the processes after the heat treatment in a reduced pressure state (steps S2 and S3).

(Comparative Example 4)
As in Example 2, a PdCu alloy film (film thickness 10 μm) prepared by a rolling method was prepared. Thereafter, the same treatment as in Comparative Example 2 was performed, and a hydrogen permeation test was performed. That is, the obtained alloy film was heat-treated in a reduced pressure state (Step S2). It cooled to room temperature with the pressure-reduced state, and after cooling, pressure was returned to atmospheric pressure and the alloy film was taken out from the high vacuum electric furnace. Then, the alloy film was transferred to a hydrogen permeation measuring device, the inside of the device was depressurized, and heated to 450 ° C. without performing oxygen treatment (step S3) in a high temperature state, and a hydrogen permeation test was performed (step S4).

Example 3
The hydrogen permeation amount of the alloy film was measured in the same procedure as in Example 1. However, the heating temperature at the time of measuring the hydrogen permeation amount was set to 300 ° C. instead of 450 ° C.

Table 1 shows the results of hydrogen permeation tests of Examples 1 to 3 and Comparative Examples 1 to 4.

As shown in Table 1, in Comparative Example 1 and Comparative Example 3, the hydrogen permeation amount was 0. That is, it was found that the alloy film does not have hydrogen permeation performance when heat treatment in a reduced pressure state is not performed. In Comparative Examples 2 and 4, the hydrogen permeation (mL / min / cm ² ) was 2.30 and 2.21, respectively. It was confirmed that hydrogen permeation performance can be imparted to the alloy film by performing heat treatment in a reduced pressure state. However, the hydrogen permeation amount was still small, and hydrogen permeation performance at a level that could be used as a hydrogen permeable membrane (for example, 3 mL / min / cm ² or more) was not obtained.

On the other hand, in Examples 1 to 3, the hydrogen permeation amount is remarkably improved as compared with Comparative Examples 2 and 4, and the hydrogen permeation performance at a level that can be used as a hydrogen permeable membrane, for example, 3 mL / min / cm ^2. Had more. That is, after the heat treatment in the reduced pressure state, the oxygen permeation in the heated state and the treatment with the reducing gas are performed, so that the hydrogen permeation amount is remarkably compared with the case where only the heat treatment in the reduced pressure state is performed. It turned out to increase.

[Examination of surface condition]
Regarding the alloy films according to Comparative Examples 1 and 3 (after Step S1 and before Step S4), Comparative Example 2 (After Step S2 and before Step S4) and Examples 1 and 2 (After Step S4), The surface state was observed by SEM photographs. Moreover, about Example 1, the surface state was observed with the SEM photograph also about the sample before the process by hydrogen gas (between step S3 and S4) after the oxygen process in a high temperature state. A SEM photograph is shown in FIG. As shown in FIG. 1, there was a great difference in surface condition between Comparative Examples 1 and 2 and Example 1. That is, it was found that the structure of the alloy film changes by performing oxygen treatment under heating conditions, reducing the pressure again while maintaining the heating state, and then introducing hydrogen to return to atmospheric pressure.

[Examination of crystal structure]
Next, X-ray diffraction intensity spectra were measured for the alloy films of Comparative Example 1 (after Step S1 and before Step S4) and Comparative Example 2 (After Step S2 and before Step S4). The measurement results are shown in FIG. As shown in FIG. 2, in Comparative Example 1, only the peak of the FCC structure (A in the figure) was observed. That is, it was found that the alloy film before the heat treatment in the reduced pressure state has an FCC structure. On the other hand, Comparative Example 2 mainly showed a peak of BCC structure (B in the figure), and a slight peak of FCC structure was also observed. Specifically, in Comparative Example 2, the peak intensity at the diffraction angle 2θ = 43 ± 0.5, which is the peak of the BCC structure, is larger than the peak intensity at the diffraction angle 2θ = 42 ± 0.5, which is the peak of the FCC structure. It was big enough. That is, it was found that the crystal structure of the alloy film according to Comparative Example 2 was mainly a BCC structure, and the FCC structure was slightly mixed.

From the result of the X diffraction intensity spectrum, it was found that at least a part of the crystal structure changes from the FCC structure to the BCC structure when the alloy film is heat-treated in a reduced pressure state. However, in Comparative Example 2 having the BCC structure, as shown in Table 1, sufficient hydrogen permeation performance is not obtained. That is, it can be understood that the desired hydrogen permeation performance cannot be obtained simply by changing the crystal structure to the BCC structure.

[Examination of mechanical properties]
Under the same conditions as in Example 1, a PdCu alloy film having a film thickness of 5 μm and 10 μm was formed by electrolytic plating using a PdCu plating solution, and the alloy film was peeled off from the substrate after plating.
Moreover, the PdCu alloy film whose film thickness is 5 micrometers and 10 micrometers was prepared by the rolling method.
Each alloy film was supported by a support member having a circular unsupported region. Next, at the center of the non-support region, a bar-shaped jig is pressed perpendicularly to the alloy film, and the amount of displacement of the alloy film and the force (test force) received by the bar-shaped jig until the alloy film is broken. The relationship was measured.
The test results are shown in FIG. Each spectrum in FIG. 3 corresponds to the following conditions.
Spectrum A: Electrolytic plating 5 μm
Spectrum B: 10 μm electrolytic plating
Spectrum C: Rolled film 5 μm
Spectrum D: Rolled film 10 μm
As shown in FIG. 3, an alloy film formed by electrolytic plating under the same conditions as in Example 1 has a larger displacement and test force until the film breaks than an alloy film obtained by rolling. It was.
That is, it was found that the alloy film obtained by electrolytic plating is more flexible than the rolled film and has excellent durability.

Claims

Including an alloy film containing Pd and Cu;
The alloy film is
Electrolytic plating film,
Having a BCC structure (body-centered-cubic);
The Pd: Cu ratio (atomic ratio) in the alloy film is 6: 4 to 4: 6.
Hydrogen permeable membrane.
2. The hydrogen permeable membrane according to claim 1, wherein the alloy membrane has a thickness of 1 to 100 μm.
Producing an alloy film containing Pd and Cu;
Changing at least part of the crystal structure of the alloy film to a BCC structure in the presence of non-oxygen;
After the step of changing to the BCC structure, the step of treating the alloy film with oxygen under heating conditions;
After the step of treating with oxygen, the step of treating the alloy film with a reducing gas,
A method for producing a hydrogen permeable membrane.
The manufacturing method according to claim 3, wherein the step of producing the alloy film includes a step of forming the alloy film by electrolytic plating.
The manufacturing method according to claim 3 or 4, wherein the step of changing to the BCC structure includes a step of heat-treating the alloy film in a reduced pressure state.
The manufacturing method according to any one of claims 3 to 5, wherein the reducing gas contains hydrogen.
Furthermore, after the step of treating with oxygen, the step of reducing the environment containing the alloy film to a reduced pressure state,
7. The process according to claim 3, wherein the step of treating with the reducing gas includes a step of introducing the reducing gas into an environment including the alloy film after the step of reducing the pressure. Manufacturing method.
The manufacturing method according to any one of claims 3 to 7, wherein the step of treating with the reducing gas is performed under heating conditions.
Furthermore,
After the step of treating with the reducing gas, the step of depressurizing the environment including the alloy film and re-depressing the environment,
After the step of reducing the pressure again, cooling the alloy film;
After the cooling step, returning the environment containing the alloy film to atmospheric pressure;
The manufacturing method in any one of Claims 3 thru | or 8 provided with these.