JP4661444B2 - Hydrogen permeable membrane and method for producing hydrogen permeable membrane - Google Patents

Description

  The present invention relates to a hydrogen permeable membrane that selectively permeates hydrogen and a method for manufacturing the hydrogen permeable membrane.

  In order to extract hydrogen from a hydrogen-containing gas, a hydrogen permeable membrane containing a hydrogen permeable metal made of palladium (Pd) has been conventionally used. As such a hydrogen permeable membrane, a metal layer containing Pd is provided on the surface of a metal layer made of a metal having high hydrogen permeable performance (for example, niobium (Nb), tantalum (Ta), vanadium (V)). A hydrogen permeable membrane whose performance is improved by adopting a structure is known (for example, see Patent Document 1).

JP-A-11-276866 JP-A-7-185277 JP-A-5-85869 JP-A-6-101083 Japanese Patent Laid-Open No. 11-50226

  However, the hydrogen permeable membrane having the multilayer structure has a problem that the hydrogen permeation performance is gradually lowered when used under a predetermined high temperature condition. Such a problem is caused by, for example, oxygen entering the hydrogen permeable membrane through the Pd layer provided on the surface of the hydrogen permeable membrane, and the metal constituting the metal layer having the high hydrogen permeable performance inside the hydrogen permeable membrane. It is thought to occur by being oxidized. Alternatively, such a problem is that the metal constituting the layer made of the metal having high hydrogen permeation performance or the metal oxide diffuses in the metal layer containing Pd, and the metal layer containing Pd. It is thought to occur by reaching the surface of

  The present invention has been made in order to solve the above-described conventional problems, and an object of the present invention is to suppress performance deterioration in the hydrogen permeable membrane.

In order to achieve the above object, a method for producing a first hydrogen permeable membrane of the present invention comprises:
(A) a first step of preparing a metal base layer containing a Group 5 metal;
(B) When forming a multilayer structure by sequentially forming a predetermined metal layer on one or both surfaces of the metal base layer , oxide, nitride or carbide is added in addition to palladium (Pd). a metal coating layer containing a second component capable of forming, a second step of forming on the surface of the multilayer structure,
And (c) a third step of narrowing or closing a gap in a crystal structure including a crystal grain boundary in the metal coating layer by oxidizing, nitriding or carbonizing the second component. .

  According to the first method for producing a hydrogen permeable membrane of the present invention configured as described above, the gap in the crystal structure including the crystal grain boundary is narrowed in the metal coating layer. It is possible to suppress the intrusion of oxygen through gaps on the crystal structure and to suppress the metal constituting the layer below the metal coating layer and the oxide from reaching the metal coating layer surface. Therefore, it is possible to suppress the deterioration of the performance of the hydrogen permeable membrane due to the penetration of oxygen and the arrival of the metal or the like constituting the lower layer.

Further, when oxidizing, nitriding or carbonizing the second component, such a reaction mainly proceeds in the vicinity of the gap on the crystal structure including the crystal grain boundary, and the second component is caused by such a reaction. Since the crystal grains containing swell expand, the gap on the crystal structure can be narrowed and closed.

In the first method for producing a hydrogen permeable membrane of the present invention,
The second component is selected from chromium (Cr), aluminum (Al), silicon (Si), titanium (Ti), iron (Fe), copper (Cu), molybdenum (Mo), and zirconium (Zr). Element,
The third step may be a step of oxidizing the second component.

  In this case, the gap on the crystal structure including the crystal grain boundary can be narrowed and closed in the metal coating layer by oxidizing the second component by the oxidation treatment. In particular, since the above elements have a relatively large degree of expansion due to oxidation, the gaps on the crystal structure can be narrowed and closed efficiently.

In the first method for producing a hydrogen permeable membrane of the present invention,
The second component is an element selected from chromium (Cr), aluminum (Al), silicon (Si), titanium (Ti), iron (Fe),
The third step may be a step of nitriding the second component.

  In this case, the gap on the crystal structure including the crystal grain boundary can be narrowed / closed in the metal coating layer by nitriding the second component by nitriding. In particular, since the above elements have a relatively large degree of expansion due to nitriding, the gaps on the crystal structure can be narrowed and closed efficiently.

Alternatively, in the first method for producing a hydrogen permeable membrane of the present invention,
The second component is an element selected from silicon (Si) and titanium (Ti),
The third step may be a step of carbonizing the second component.

  In this case, by carbonizing the second component by the carbonization treatment, the gap on the crystal structure including the crystal grain boundary can be narrowed and closed in the metal coating layer. In particular, since the above elements have a relatively large degree of expansion due to carbonization, it is possible to efficiently narrow and close the gaps on the crystal structure.

In the first method for producing a hydrogen permeable membrane of the present invention,
The metal coating layer formed in the second step may contain Pd as a whole, and only a limited region including the surface of the metal coating layer may further include the second component.

  With such a configuration, in a limited region including the surface of the metal coating layer, the gap on the crystal structure including the crystal grain boundary is narrowed or closed, so that the intrusion of oxygen and the lower layer can be prevented. The performance deterioration of the hydrogen permeable membrane due to the arrival of the metal or the like constituting the surface can be suppressed. Moreover, since the area | region with which a 2nd component is provided is limited, the fall of the hydrogen permeation performance resulting from adding a 2nd component to a metal coating layer can be suppressed.

In the first method for producing a hydrogen permeable membrane of the present invention,
(D) It is good also as providing the 4th process of forming a palladium layer on the metal coating layer before or after the 3rd process.

  With such a configuration, by forming the palladium layer, it is possible to ensure the activity of promoting the dissociation reaction of hydrogen molecules on the surface of the hydrogen permeable membrane or the binding reaction to hydrogen molecules. Transmission performance can be improved.

The second method for producing a hydrogen permeable membrane of the present invention is as follows.
(A) a first step of preparing a metal base layer containing a Group 5 metal;
(B) a second component capable of forming an oxide, nitride, or carbide when a predetermined metal layer is sequentially formed on one or both surfaces of the metal base layer to form a multilayer structure; And a second step of forming a metal coating layer provided in addition to palladium (Pd) on the surface of the multilayer structure.

  According to the second method for producing a hydrogen permeable membrane of the present invention configured as described above, further oxidation, nitridation, or carbonization is performed to oxidize the second component in the vicinity of the gap on the crystal structure, By nitriding or carbonizing, the crystal grains containing the second component can be expanded to narrow and close the gap on the crystal structure including the crystal grain boundary in the metal coating layer. Further, if the environment in which the hydrogen permeable membrane is used is an environment in which an oxidation reaction, a nitridation reaction or a carbonization reaction can proceed with respect to the second component, the gap on the crystal structure can be reduced while the hydrogen permeable membrane is used. Occlusion can proceed.

The third method for producing a hydrogen permeable membrane of the present invention is as follows.
(A) a first step of preparing a metal base layer containing a Group 5 metal;
(B) When a predetermined metal layer is sequentially formed on one or both surfaces of the metal base layer to form a multilayer structure, in addition to palladium (Pd), at the use temperature of the hydrogen permeable membrane a first metallization layer Ru consists compound containing the second component in an amount exceeding a solid solubility limit, and a second step of forming on the surface of the multilayer structure,
(C) In the metal coating layer, by performing a heat treatment for precipitating the second compound having a higher content ratio of the second component than the first compound in a gap in a crystal structure including a crystal grain boundary , A third step of narrowing or closing the gap;
It is a summary to provide.

  With such a configuration, the second compound precipitates in the gap on the crystal structure in the metal coating layer by the heat treatment, so that the gap can be narrowed and closed by the second compound.

In such a third method for producing a hydrogen permeable membrane of the present invention,
(D) It is good also as providing the 4th process of oxidizing, nitriding, or carbonizing the 2nd element in the deposited 2nd compound with the 3rd process or after the 3rd process.

  With such a configuration, the second compound precipitated in the gap on the crystal structure expands by oxidizing, nitriding, or carbonizing the second element, and thus the effect of narrowing and closing the gap. Can be increased.

In such a third method for producing a hydrogen permeable membrane of the present invention,
(E) It is good also as providing the 5th process of forming a palladium layer on the said metal coating layer after the said 3rd process.

  With such a configuration, by forming the palladium layer, it is possible to ensure the activity of promoting the dissociation reaction of hydrogen molecules on the surface of the hydrogen permeable membrane or the binding reaction to hydrogen molecules. Transmission performance can be improved.

The fourth method for producing a hydrogen permeable membrane of the present invention is as follows.
(A) a first step of preparing a metal base layer containing a Group 5 metal;
(B) When a predetermined metal layer is sequentially formed on one or both surfaces of the metal base layer to form a multilayer structure, in addition to palladium (Pd), at the use temperature of the hydrogen permeable membrane And a second step of forming, on the surface of the multilayer structure, a metal coating layer containing a second component in an amount exceeding the solid solution limit.

According to the fourth method for producing a hydrogen permeable membrane of the present invention configured as described above, further heat treatment is performed to precipitate the compound containing the second component in the gaps on the crystal structure. The gap can be narrowed and closed.

The fifth method for producing a hydrogen permeable membrane of the present invention is as follows.
(A) a first step of preparing a metal base layer containing a Group 5 metal;
(B) When forming a multilayer structure by sequentially forming predetermined metal layers on one or both surfaces of the metal base layer, a metal coating layer containing palladium (Pd) is formed on the surface of the multilayer structure. A second step of forming
(C) A film is formed on the metal coating layer using a predetermined film forming material to form a plugging coating layer that covers the metal coating layer. A third step of narrowing or closing the gap in the crystal structure including the boundary;
And (d) and summarized in that and a fourth step of removing the first filling coating layer formed on said metallized layer.

  With such a configuration, by forming a plugging coating layer on the metal coating layer, the deposition material enters the gap on the crystal structure on the surface of the metal coating layer, thereby narrowing the gap.・ Can be blocked. Further, by removing the plugging coating layer, it is possible to ensure the activity of promoting the dissociation reaction of hydrogen molecules or the binding reaction to hydrogen molecules on the surface of the hydrogen permeable membrane.

In the fifth method for producing a hydrogen permeable membrane of the present invention,
(E) It is good also as providing the 5th process of oxidizing, nitriding, or carbonizing the film-forming material which constitutes the plugging coating layer before or after the 4th process.

  With such a configuration, the film forming material that has entered the gap on the crystal structure expands due to oxidation, nitridation, or carbonization, so that the effect of narrowing or closing the gap on the crystal structure can be enhanced.

In the fifth method for producing a hydrogen permeable membrane of the present invention,
The film forming material used in the third step is a material capable of forming an oxide,
The fourth step may be a step of removing the plugging coating layer by dry etching using oxygen plasma or ozone plasma.

  With such a configuration, it is possible to simultaneously remove the plugging coating layer and oxidize the film forming material that has entered the gaps in the crystal structure.

Alternatively, in the fifth method for producing a hydrogen permeable membrane of the present invention,
The fourth step may be a step of removing the plugging coating layer by physical polishing using abrasive particles made of oxide, nitride, or carbide generated from the film forming material.

  With such a configuration, even if the abrasive particles used for removing the capping coating layer remain on the hydrogen permeable membrane, the deterioration of the hydrogen permeation performance due to the remaining abrasive particles is suppressed. Can do.

In the fifth method for producing a hydrogen permeable membrane of the present invention,
The third step may be a step of forming the plugging coating layer by using a film forming material that can exist stably under use conditions of the hydrogen permeable film.

  With such a configuration, there is no need for further processing in order to enable the formed clogging coating layer to exist stably.

In the fifth method for producing a hydrogen permeable membrane of the present invention, the film forming material may be an oxide, a nitride, or a carbide. If these are used as the film forming material, the film forming material does not diffuse in the hydrogen permeable film, and the film forming material can be stably present in the gap on the crystal structure.

In the fifth method for producing a hydrogen permeable membrane of the present invention,
In the fourth step, the surface layer may be removed by physical polishing using abrasive particles made of the film forming material used in the third step.

  With such a configuration, even if the abrasive particles used for removing the capping coating layer remain on the hydrogen permeable membrane, the deterioration of the hydrogen permeation performance due to the remaining abrasive particles is suppressed. Can do.

In the fifth method for producing a hydrogen permeable membrane of the present invention described above,
(F) After the third step, prior to the fourth step, a temperature lower than the melting point of the metal constituting the hydrogen permeable membrane with respect to the metal coating layer having the plugging coating layer made of the element. It is good also as providing the 6th process which performs the heat processing in.

  With such a configuration, the film forming material that has entered the gap on the crystal structure moves further into the gap with the heat treatment. Therefore, after removing the plugging coating layer in the fourth step, a more sufficient amount of plugging material can be left in the gap.

The sixth method for producing a hydrogen permeable membrane of the present invention is as follows.
(A) a first step of preparing a metal base layer containing a Group 5 metal;
(B) When forming a multilayer structure by sequentially forming predetermined metal layers on one or both surfaces of the metal base layer, a metal coating layer containing palladium (Pd) is formed on the surface of the multilayer structure. A second step of forming
(C) forming a crystal grain boundary covering portion that covers only a limited region including the crystal grain boundary existing on the surface of the metal coating layer on the surface of the metal coating layer; A third step of narrowing or closing a gap in a crystal structure including a grain boundary;
It is a summary to provide.

  With such a configuration, the gap on the crystal structure on the surface of the metal coating layer can be narrowed and closed by covering the gap on the crystal structure with the crystal grain boundary coating portion.

In the sixth method for producing a hydrogen permeable membrane of the present invention, further,
(D) It is good also as providing the 4th process of oxidizing, nitriding, or carbonizing the said film-forming material which comprises the said crystal grain boundary coating | coated part.

  With such a configuration, the film forming material constituting the crystal grain boundary covering portion does not diffuse in the hydrogen permeable film, and the film forming material can stably exist in the gap on the crystal structure. Is possible.

In the sixth method for producing a hydrogen permeable membrane of the present invention,
The crystal grain boundary covering portion is formed using an element selected from chromium (Cr), silicon (Si), and aluminum (Al) as a film forming material,
The fourth step may be a step of oxidizing the film forming material.

  With such a configuration, it is possible to suppress the intrusion of oxygen into the hydrogen permeable film and the progress of the oxidation reaction inside the hydrogen permeable film during the use of the hydrogen permeable film.

In the sixth method for producing a hydrogen permeable membrane of the present invention,
In the third step, the crystal grain boundary coating portion may be formed using a film forming material that can exist stably under the use condition of the hydrogen permeable film.

  With such a configuration, no further processing is required in order to allow the formed crystal grain boundary covering portion to exist stably.

In the sixth method for producing a hydrogen permeable membrane of the present invention, the film forming material may be an oxide, a nitride, or a carbide.

  With such a configuration, it is not necessary to separately perform a process such as oxidation, nitridation, or carbonization in order to stabilize the film forming material constituting the crystal grain boundary covering portion.

In the sixth method for producing a hydrogen permeable membrane of the present invention,
The crystal grain boundary covering portion may be formed using an oxide selected from chromium oxide, silicon oxide, and aluminum oxide as a film forming material.

  With such a configuration, it is possible to suppress the intrusion of oxygen into the hydrogen permeable film and the progress of the oxidation reaction inside the hydrogen permeable film during the use of the hydrogen permeable film.

In the sixth method for producing a hydrogen permeable membrane of the present invention,
The third step includes
(C-1) A film formation area acquisition step of measuring or estimating the area of the vicinity of the crystal grain boundary existing on the surface of the metal coating layer as the area to be formed;
(C-2) Based on the measured or estimated area and the atomic radius or lattice constant of the film forming material used for forming the crystal grain boundary covering portion, the amount of the film forming material to be used for film forming is determined. A film forming material amount setting step to be set;
(C-3) It is good also as providing the film-forming process which forms into a film on the said metal coating layer using the film-forming material of the quantity set at the said film-forming material amount setting process.

  With such a configuration, the grain boundary covering portion that covers only a limited region including the crystal grain boundary existing on the surface of the metal coating layer by performing film formation by setting the amount of the film forming material to be used. Can be easily formed.

In the sixth method for producing a hydrogen permeable membrane of the present invention,
(E) Prior to the third step, a fifth step of enlarging the crystal grains on the surface of the metal coating layer may be provided.

  With such a configuration, the amount of film forming material used for forming the crystal grain boundary covering portion can be reduced. In addition, the film formation time for forming the crystal grain boundary covering portion can be shortened.

Alternatively, in the sixth method for producing a hydrogen permeable membrane of the present invention,
(F) Prior to the third step, a sixth step of making the crystal grain boundary on the surface of the metal coating layer concave may be provided.

  With such a configuration, the gap on the crystal structure existing on the surface of the metal coating layer is further activated, so that the formation of the crystal grain boundary coating portion becomes easier. Moreover, when measuring the area of the crystal grain boundary vicinity area | region which exists in the surface of a metal coating layer, the precision of a measurement can be improved.

  The present invention can be realized in various forms other than the above, for example, a form of a hydrogen permeable film manufactured by the method for manufacturing a hydrogen permeable film of the present invention, a hydrogen extraction apparatus using the hydrogen permeable film, a fuel cell, or the like. This can be realized.

Next, embodiments of the present invention will be described in the following order based on examples.
A. Configuration of hydrogen permeable membrane:
B. Production method of the hydrogen permeable membrane of the first embodiment:
C. Modification of the first embodiment:
D. Second embodiment:
E. Third embodiment:
F. Modification of the third embodiment:
G. Fourth embodiment:
H. Modification of the fourth embodiment:
I. Check the effect:
J. et al. Equipment using hydrogen permeable membrane:
K. Variations:

A. Configuration of hydrogen permeable membrane:
FIG. 1 is a schematic cross-sectional view showing an outline of the configuration of a hydrogen permeable membrane 10 according to the first embodiment. The hydrogen permeable membrane 10 has a five-layer structure including a metal base layer 12, an intermediate layer 14 formed on both surfaces of the metal base layer, and a metal coating layer 16 formed on each intermediate layer 14. is doing.

  The metal base layer 12 is formed of a metal containing V, such as vanadium (V) or a vanadium alloy containing V as a main component in a proportion exceeding 50%, and is a metal layer exhibiting excellent hydrogen permeability. is there.

  The metal coating layer 16 is made of a metal containing Pd, such as a palladium (Pd) alloy containing Pd as a main component in a proportion exceeding 50%. More specifically, in this embodiment, it is formed of an alloy of Pd and chromium (Cr). The metal coating layer 16 is a layer that functions as a catalyst layer having an activity of promoting the dissociation reaction of hydrogen molecules on the surface of the hydrogen permeable membrane or the binding reaction to hydrogen molecules. In addition, although the metal coating layer 16 of a present Example is characterized by providing a predetermined oxide in the crystal grain boundary with which this metal coating layer 16 is provided, the detailed structure of the metal coating layer 16 is demonstrated later.

  The intermediate layer 14 is a layer made of a hydrogen permeable metal having a composition different from that of the metal base layer 12 and the metal cover layer 16, and prevents metal diffusion between the metal base layer 12 and the metal cover layer 16. It is a layer to be provided. In this embodiment, the intermediate layer 14 is formed of tantalum (Ta).

B. Production method of the hydrogen permeable membrane of the first embodiment:
FIG. 2 is a process diagram showing a method for manufacturing the hydrogen permeable membrane 10. When manufacturing the hydrogen permeable membrane 10, first, a metal layer containing V to be the metal base layer 12 is prepared (step S100). The metal layer prepared in step S100 can be produced, for example, by repeating the rolling and annealing processes on the metal ingot containing V as a main constituent, and by such a process, an extremely dense crystalline material is produced. A metal layer consisting of can be obtained. In step S100, the surface of the prepared metal layer is etched with an alkaline solution to remove impurities such as an oxide film formed on the surface.

  After step S100, an intermediate layer 14 made of Ta is formed on each of both surfaces of the prepared metal base layer 12 (step S110). The intermediate layer 14 can be formed by, for example, a PVD method, a CVD method, or a plating process such as electroless plating or electrolytic plating.

  After the intermediate layer 14 is formed, a Pd alloy layer made of a Pd alloy containing Cr is then provided on each intermediate layer 14 (step S120) to form a laminate having a five-layer structure. The Pd alloy layer can be formed by, for example, a PVD method, a CVD method, or a plating process such as electroless plating or electrolytic plating, and is formed as a metal layer having a crystal structure.

  After the formation of the Pd alloy layer, if the above laminated body provided with the Pd alloy layer is oxidized (step S130), the Pd alloy layer becomes the metal coating layer 16 and the hydrogen permeable membrane 10 is completed. The Here, the oxidation treatment can be, for example, a heat treatment in an oxidizing atmosphere. That is, the laminated body may be exposed to a high-temperature oxidizing atmosphere, whereby the Cr contained in the Pd alloy layer is oxidized. The temperature at which the oxidation treatment is performed may be a temperature lower than the melting point of the metal constituting the laminate, and the oxidation reaction can be activated by increasing the temperature, but the metal that proceeds in the laminate during the oxidation treatment It is desirable to set so that the diffusion is acceptable. Therefore, the conditions for the oxidation treatment may be performed, for example, in air at 400 to 500 ° C. for about 2 to 10 hours. Note that the oxidation treatment in step S130 may be anodic oxidation, ozone heat treatment, or oxygen plasma treatment in addition to the heat treatment in the oxidizing atmosphere.

Since the Pd alloy layer has a crystal structure as described above, crystal grain boundaries are formed between crystal grains constituting the Pd alloy layer. This crystal grain boundary is a portion where the crystal lattice constituting the crystal structure is discontinuous, and can be said to be a fine gap existing in the crystal structure. When the oxidation treatment is performed in step S130, the Pd alloy layer is gradually oxidized from Cr that is easily supplied with oxygen among Cr contained in the Pd alloy layer. Specifically, in addition to Cr existing in the vicinity of the surface in the Pd alloy layer, Cr existing in the vicinity of the grain boundary surface formed in the Pd alloy layer is oxidized to produce chromium oxide (Cr ₂ O ₃ ). Form. Thus, when Cr oxidizes, oxygen atoms enter into the crystals constituting the Pd alloy layer, so that the crystal structure expands in the region where the oxidation proceeds. Thus, Cr becomes chromium oxide and expands as a whole, thereby narrowing and closing the gap on the crystal structure including the crystal grain boundary formed in the Pd alloy layer.

  When the hydrogen permeable membrane 10 is manufactured, the thickness of each layer may be set according to the hydrogen permeation performance and strength required based on the application. For example, the metal base layer can be 10 to 100 μm. The metal coating layer 16 can be 0.1 to 1.0 μm. Since the metal coating layer 16 is a layer that functions as a catalyst layer as described above, it can be made thinner than the metal base layer 12. In addition, the intermediate layer 14 is desirably formed thicker in order to prevent metal diffusion between the metal base layer 12 and the metal coating layer 16, but prevents metal diffusion if interposed between the both. Therefore, it may be formed thinner than the metal coating layer 16. Therefore, for example, the thickness can be about 0.01 to 10 μm.

  According to the hydrogen permeable membrane 10 of the present embodiment configured as described above, the metal coating layer 16 provided on the surface of the hydrogen permeable membrane 10 oxidizes Cr contained in the metal coating layer 16 to crystallization. Gaps on the crystal structure including the grain boundaries are narrowed and closed. Therefore, it is possible to suppress the entry of oxygen from the surface of the hydrogen permeable membrane 10 into the hydrogen permeable membrane 10 through the gap in the crystal structure. Thereby, the oxidation of the metal (hereinafter referred to as the lower layer metal) constituting the lower layer of the metal coating layer 16 can be suppressed. Specifically, a decrease in hydrogen permeation performance due to oxidation of V constituting the metal base layer 12 and Ta constituting the intermediate layer 14 can be suppressed.

  In addition, according to the present embodiment, by narrowing and closing the gap on the crystal structure, V constituting the lower layer metal, particularly the metal base layer 12, passes through the gap on the crystal structure of the metal coating layer 16. Reaching the surface of the metal coating layer 16 can be suppressed. In the hydrogen permeable membrane, the lower layer metal reaches the surface of the metal coating layer 16 mainly through a gap on the crystal structure including the crystal grain boundary in the metal coating layer 16. Then, when the lower layer metal reaches the surface of the metal coating layer 16 and the surface of the metal coating layer 16 is covered, the activity of promoting the dissociation reaction of hydrogen molecules or the binding reaction to the hydrogen molecules in the covered region. Inhibited, hydrogen permeation performance decreases. In this example, the above-mentioned performance degradation can be suppressed by narrowing and closing the gap on the crystal structure to suppress the movement of V.

The inconvenience caused by oxygen entering the hydrogen permeable membrane 10 and oxidizing the lower layer metal is not only due to the oxidation of V and the like, but also the hydrogen permeation performance is lowered. It is also caused by the formation of vanadium oxide (V ₂ O ₅ ) having a lower melting point. That is, since a substance having a lower melting point has a property of being easily moved, when V constituting the metal base layer 12 is oxidized, the generated vanadium oxide is more easily formed on the crystal structure than V. It moves to the surface of the hydrogen permeable membrane using the gap as the main path, and covers the surface of the hydrogen permeable membrane. In this embodiment, since the gap on the crystal structure of the metal coating layer 16 is narrowed and closed by oxidation treatment, the progress of oxidation of V constituting the metal base layer 12 is suppressed, and a low melting point compound is used. The production of certain vanadium oxides can be suppressed. Even if vanadium oxide is generated, the movement of the vanadium oxide to the surface of the hydrogen permeable membrane can be suppressed because the gap on the crystal structure serving as the movement path is narrowed and closed.

In this example, chromium oxide is formed in the gaps on the narrowed and closed crystal structure, but the vanadium oxide moved from the lower layer passes through the gaps on the crystal structure. In this case, chromium oxide and vanadium oxide react. Then, by such a reaction, a complex oxide of chromium oxide and vanadium oxide _{(V 2 O 5 · Cr 2} O 3) is formed. This composite oxide has a higher melting point than V and vanadium oxide, and is a compound that hardly moves in the hydrogen permeable membrane. Therefore, even if V or vanadium oxide moves from the lower layer, the composite oxide is formed in the gap on the crystal structure of the metal coating layer 16, so that the surface of the hydrogen permeable membrane of V or vanadium compound is formed. Further movement of the can be suppressed.

C. Modification of the first embodiment:
(C-1) First modification:
In the first embodiment, the entire Pd alloy layer serving as the metal coating layer 16 includes Cr, but only a part of the metal coating layer 16 including Pd may include Cr in a layered manner. For example, only a limited region including the surface (the surface of the hydrogen permeable film 10) in the metal coating layer 16 may include Cr. If the hydrogen permeable membrane having such a metal coating layer is subjected to an oxidation treatment in the same manner as in the first embodiment, Cr is oxidized in the region including the surface, so that the crystal structure including the crystal grain boundary is included. The gap is narrowed and closed.

  With such a configuration, since the gap on the crystal structure is narrowed and closed near the surface of the metal coating layer, oxygen penetration into the hydrogen permeable membrane is suppressed as in the first embodiment. Further, oxidation of the lower layer metal can be suppressed. In addition, the lower metal, particularly the metal constituting the metal base layer 12 and its oxide can be prevented from reaching the surface of the hydrogen permeable membrane. Furthermore, by including Cr only in a limited region of the metal coating layer, it is possible to suppress a decrease in hydrogen permeation performance due to the Cr content in the metal coating layer 16.

(C-2) Second modification:
In the hydrogen permeable membrane 10 of the first embodiment, Cr in the Pd alloy layer is oxidized to form the metal coating layer 16 in which the gap on the crystal structure is narrowed and closed, and then further on the metal coating layer 16. Alternatively, a Pd layer made of high-purity Pd may be formed. When the oxidation treatment in step S130 is performed, chromium oxide is also formed on the surface of the metal coating layer 16, so that the catalytic activity on the surface of the hydrogen permeable membrane may be reduced due to the chromium oxide formed on the surface. However, by further providing a Pd layer, the catalytic activity on the surface of the hydrogen permeable membrane can be ensured and performance degradation can be prevented. Since the Pd layer only needs to ensure catalytic activity on the surface of the hydrogen permeable membrane, it can be formed thinner than the metal coating layer 16.

  Alternatively, after the Pd alloy layer is formed in step S120, the Pd layer may be formed on the Pd alloy layer prior to the oxidation treatment in step S130. When oxidation treatment is performed after the Pd layer is formed, the Pd alloy layer contains oxygen due to oxygen that has entered the Pd alloy layer through the Pd layer (via a gap on the crystal structure including the crystal grain boundary included in the Pd layer). Cr is oxidized. In this case as well, the effect of narrowing and closing the gap on the crystal structure in the metal coating layer and the effect of ensuring the catalytic activity of the hydrogen permeable membrane surface by the Pd layer are obtained. Can do.

(C-3) Third modification:
In the first embodiment, the oxidation process in step S130 can be omitted. That is, after providing a Pd alloy layer in step S120 to form a laminate having a five-layer structure, the laminate may be used as a hydrogen permeable membrane without being subjected to oxidation treatment. In this case, the same effect can be obtained by the Cr included in the Pd alloy layer being oxidized in the process of using it as a hydrogen permeable membrane, and the gap on the crystal structure being narrowed and closed.

(C-4) Fourth modification:
In the first embodiment, Cr is used as the second component that is added to the metal coating layer 16 to form the oxide to form the Pd alloy. However, other types of elements can also be used as the second component. The second component added to the metal coating layer 16 is, for example, Cr, aluminum (Al), silicon (Si), titanium (Ti), iron (Fe), copper (Cu), molybdenum (Mo), zirconium (Zr). An element selected from magnesium (Mg) and calcium (Ca) can be used. In particular, Cr, Al, and Si are preferable. This is because these elements are oxidized at a relatively low rate, but once oxidized, further oxidation is difficult to proceed. In other words, in order to oxidize these elements and ensure the narrowing and closing of the gaps in the crystal structure, it is desirable to perform sufficient oxidation treatment at a temperature higher than the operating temperature of the hydrogen permeable membrane. If the treatment is performed, further oxidation is unlikely to proceed. Therefore, further oxygen intrusion into the coating layer during use can be suppressed, and the effect of suppressing oxidation of the metal base layer 12 can be further enhanced. If an element selected from Cr, Mg, and Ca is used as the second component, a complex oxide having a high melting point can be formed in the hydrogen permeable membrane. And the effect of suppressing the movement of the V oxide to the film surface can be enhanced. Note that the amount of the second component added to the metal coating layer 16 depends on the degree of effect due to the oxide being formed and the gap on the crystal structure being narrowed and closed, and the addition of the second component to Pd. What is necessary is just to set suitably in consideration of the grade of the fall of hydrogen permeation performance by being alloyed.

(C-5) Fifth modification:
Instead of the configuration in which the metal coating layer 16 to which the second component such as Cr is added is subjected to an oxidation treatment in order to narrow and close the gap on the crystal structure in the metal coating layer 16, a predetermined second component is used. The added metal coating layer 16 may be subjected to nitriding treatment or carbonizing treatment. When forming nitrides or carbides, the crystal structure expands in the same way as when oxides are formed, and the gaps on the crystal structure can be narrowed and closed.

  The second component added to the Pd alloy layer for forming the nitride can be, for example, an element selected from Cr, Al, Si, Ti, and Fe. In this case, as the nitriding treatment instead of the oxidation treatment in step S130, for example, heat treatment in a nitrogen atmosphere or nitrogen plasma treatment may be performed. Alternatively, the laminated body may be used as a hydrogen permeable film without special nitriding treatment, and the element may be nitrided in the process of using it as a hydrogen permeable film.

  Moreover, the 2nd component added to a Pd alloy layer for carbide | carbonized_material formation can be made into the element selected from Si and Ti, for example. In this case, as the carbonization treatment instead of the oxidation treatment in step S130, for example, heat treatment in a carbon-containing gas (for example, hydrocarbon gas) atmosphere or carbon plasma treatment may be performed. Alternatively, the laminate may be used as a hydrogen permeable membrane without being specially carbonized, and the above elements may be carbonized in the process of using it as a hydrogen permeable membrane.

  As described above, even when nitriding or carbonizing is performed instead of oxidation, only the surface of the metal coating layer includes the second component for forming the nitride or carbide, or the metal coating layer. Similar modifications can be made, such as further providing a Pd layer on the surface.

D. Second embodiment:
Like the hydrogen permeable membrane 10 of the first embodiment shown in FIG. 1, the hydrogen permeable membrane of the second embodiment contains a metal base layer 12 made of V or V alloy, an intermediate layer 14 made of Ta, and Cr. And a metal coating layer 16 made of a Pd alloy. The hydrogen permeable membrane of the second embodiment is different from the first embodiment in the manufacturing method according to the metal coating layer 16.

  FIG. 3 is a process diagram showing the method for manufacturing the hydrogen permeable membrane of the second embodiment. When manufacturing the hydrogen permeable membrane of the second embodiment, the metal base layer 12 is prepared (step S200), and the intermediate layer 14 is formed thereon, as in steps S100 and S110 of the first embodiment. (Step S210). Thereafter, a Cr-containing Pd alloy layer is formed on the intermediate layer 14 in the same manner as in Step S120 (Step S220), and a laminate having a five-layer structure is formed. However, the Pd alloy layer formed in step S220 of the second embodiment is particularly characterized in that it contains Cr in a proportion exceeding the solid solubility limit at the use temperature of the hydrogen permeable membrane. The solid solubility limit is the minimum equilibrium concentration at which Cr, which is a metal different from Pd, precipitates from the Pd alloy. That is, when the Cr concentration is lower than the solid solubility limit, Cr exists as a solid solution in the Pd alloy, and when the Cr concentration is higher than the solid solubility limit, Cr precipitates in a predetermined compound state. . However, when a Pd alloy layer is formed by PVD or CVD, even if the Cr concentration exceeds the solid solubility limit, a Pd alloy layer in which Pd and Cr exist uniformly is formed regardless of the equilibrium state. be able to. Therefore, the Pd alloy layer formed in step S220 is in a state where Pd and Cr are uniformly mixed, that is, a supersaturated solid solution.

  Next, a Cr compound is precipitated in the Pd alloy layer by heat-treating the above-mentioned laminate (Step S225). When the Pd alloy layer, which is a supersaturated solid solution, is heat-treated, Cr that has been excessively dissolved is precipitated as a predetermined Cr compound containing Pd. Since such precipitation mainly proceeds in the gap on the crystal structure including the crystal grain boundary, the above heat treatment causes the Cr compound to precipitate in the gap on the crystal structure such as the crystal grain boundary in the Pd alloy layer. That is, the deposited Cr compound narrows and closes the gap on the crystal structure in the Pd alloy layer. The composition of the precipitated Cr compound is determined by the equilibrium state according to the Cr concentration and temperature in the Pd alloy layer, and becomes a Cr compound having a higher Cr concentration than the Pd alloy before the heat treatment. In the heat treatment in step S225, the temperature of the laminate is raised to a temperature equal to or higher than the use temperature of the hydrogen permeable membrane and maintained at a temperature equivalent to the use temperature of the hydrogen permeable membrane, thereby achieving an equilibrium state at the use temperature of the hydrogen permeable membrane. A corresponding precipitation state can be obtained.

  Next, when the same oxidation treatment as in step S130 is performed on the laminate in which the Pd compound is deposited on the Pd alloy layer (step S230), the Pd alloy layer becomes the metal coating layer 16, and the hydrogen permeable membrane. Is completed. By this oxidation treatment, Cr in the Pd alloy layer is oxidized. As described above, the oxidation mainly proceeds in the gaps in the crystal structure such as the crystal grain boundaries, so that Cr in the Cr compound precipitated in the gaps in the crystal structure is mainly oxidized. By being oxidized in this way, the precipitated Cr compound expands, and the degree of narrowing and closing of the gap on the crystal structure increases.

  According to the hydrogen permeable membrane of the second embodiment configured as described above, the gap on the crystal structure is narrowed and closed in the metal coating layer 16 by the precipitated Cr compound. As a result, it is possible to suppress the intrusion of oxygen through the gaps on the crystal structure and to prevent the lower layer metal and its oxide from reaching the surface of the metal coating layer. Therefore, it is possible to suppress the deterioration of the performance of the hydrogen permeable membrane due to the invasion of oxygen and the arrival of the lower layer metal. In particular, in the second embodiment, in addition to the heat treatment for the precipitation of the Cr compound, the oxidation treatment is further performed to expand the precipitated Cr compound, thereby narrowing and closing the gap on the crystal structure. The effect by this can be further enhanced.

  In the second embodiment, the oxidation process of step S230 is performed after the heat treatment process of step S225. However, these processes may be performed simultaneously. That is, by performing heat treatment in an oxidizing atmosphere, the precipitation of the Cr compound in the gaps on the crystal structure and the oxidation of Cr in the precipitated Cr compound may be performed simultaneously.

  Similarly to the second modification of the first embodiment, a Pd layer is further formed on the metal coating layer 16 (Pd alloy layer) after the heat treatment and oxidation treatment or prior to the heat treatment and oxidation treatment steps. To ensure catalytic activity on the surface of the hydrogen permeable membrane.

  Further, as in the third modification of the first embodiment, the oxidation treatment is omitted, and the Cr in the deposited Cr compound is oxidized during use of the hydrogen permeable membrane, thereby narrowing the gap on the crystal structure. -Occlusion may be advanced. Alternatively, in addition to the omission of the oxidation treatment, the heat treatment in step S225 may be omitted. In this case, during the use of the hydrogen permeable membrane, the Cr compound gradually precipitates in the gaps on the crystal structure as the temperature of the hydrogen permeable membrane rises, and the Cr in the deposited Cr compound is oxidized. The same effect as the embodiment can be obtained.

  Further, the second component added to Pd at a concentration exceeding the solid solubility limit in order to form a metal coating layer by precipitating a compound in the gap on the crystal structure is the same as in the fourth modification of the first embodiment. Various elements can be selected.

  Or you may select the element similar to the 5th modification of 1st Example as a 2nd component added to a Pd alloy layer by the density | concentration exceeding a solid solubility limit in order to form a metal coating layer. In this case, a nitriding process or a carbonizing process may be performed instead of the oxidation process in step S230. In the case of performing nitriding or carbonizing, the same effect as that of further narrowing the gap on the crystal structure in which the predetermined compound is precipitated can be obtained as in the case of performing the oxidizing treatment. Alternatively, the nitriding treatment or carbonization treatment may be omitted, and nitriding or carbonization of the second component in the deposited compound may be advanced during use of the hydrogen permeable membrane.

  The second component added to the Pd alloy layer may be an element that does not cause a reaction such as oxidation, nitridation, and carbonization. What is necessary is just to be able to exist stably in the use environment of a hydrogen permeable film, when it precipitates in the space | gap on a crystal structure as a compound by heat processing. That is, if it is difficult to cause a reaction that hinders hydrogen permeation performance without diffusing into the hydrogen permeation film when the compound deposited in the gaps in the crystal structure is left as it is or is subjected to treatment such as oxidation, A similar effect can be obtained by narrowing and closing the structural gap.

E. Third embodiment:
The hydrogen permeable membrane of the third embodiment is similar to the hydrogen permeable membrane of the first embodiment shown in FIG. 1 in addition to the metal base layer 12 made of V or V alloy, the intermediate layer 14 made of Ta, and Pd. Furthermore, it has a 5 layer structure provided with the metal coating layer 16 containing Cr. The hydrogen permeable membrane of the third embodiment is different from the first embodiment in the manufacturing method according to the metal coating layer 16.

  FIG. 4 is a process diagram showing the method for manufacturing the hydrogen permeable membrane of the third embodiment. When manufacturing the hydrogen permeable membrane of the third embodiment, the metal base layer 12 is prepared (step S300), and the intermediate layer 14 is formed thereon, as in steps S100 and S110 of the first embodiment. (Step S310). Thereafter, a Pd layer is formed on the intermediate layer 14 (step S320), and a laminate having a five-layer structure is formed. The Pd layer is a layer made of Pd alone or a layer made of a Pd alloy containing Pd as a main component.

  Next, a clogging coating layer made of Cr is formed on the Pd layer (step S323). The plugging coating layer only needs to have a thickness capable of covering the Pd layer, and can be formed by, for example, PVD or CVD. In the gap between the crystal structure including the crystal grain boundary on the surface of the Pd layer by forming the clogging coating layer by the method of supplying the film forming material onto the film forming substrate in an atomic state like PVD or CVD. The metal that constitutes the plugging coating layer (hereinafter referred to as a plugging metal) can enter. That is, the gap on the crystal structure can be narrowed / closed by the metal for filling, that is, Cr.

  Once the plugging coating layer is formed, the laminate on which the packing coating layer is formed is then heat treated (step S326). The heat treatment is a treatment for moving the filling metal from the surface of the laminate into the gap such as the crystal grain boundary. As described above, for the purpose of moving the metal for packing, it is necessary to perform heat treatment at a temperature as high as possible below the melting point of the metal constituting the laminate, but metal diffusion that proceeds in the laminate during the heat treatment is performed. It is desirable to set the temperature of the heat treatment so as to keep it within an allowable range. Therefore, the heat treatment may be performed, for example, at 400 to 500 ° C. for about 1 to 2 hours.

  Thereafter, the laminate subjected to the heat treatment is further oxidized (step S330). This oxidation process is the same process as step S130. By applying an oxidation treatment, Cr, which is a filling metal, is oxidized to become chromium oxide. By being oxidized in this way, the crystal structure of Cr that has entered the gaps in the crystal structure expands.

  When the oxidation treatment is performed, the surface layer of the laminate is further removed, that is, the plugging coating layer is removed (step S240), thereby completing the hydrogen permeable membrane. The surface layer can be removed, for example, by argon ion etching, physical polishing, or chemical etching. By performing such surface layer removal and removing the clogging coating layer, the laminate becomes a hydrogen permeable membrane having a metal coating layer 16 composed of a Pd layer on the surface. In the metal coating layer 16 provided in the hydrogen permeable membrane of the third embodiment, in the region in the vicinity of the surface including the surface, the gap on the crystal structure is in a state of being narrowed and closed by chromium oxide.

  According to the hydrogen permeable film of the third embodiment configured as described above, since the gap on the crystal structure is narrowed and closed by chromium oxide in the metal coating layer 16, the crystal inside the hydrogen permeable film It is possible to suppress the intrusion of oxygen through the structural gap, and to suppress the arrival of the lower layer metal and its oxide on the surface of the metal coating layer. Therefore, it is possible to suppress the deterioration of the performance of the hydrogen permeable membrane due to the invasion of oxygen and the arrival of the lower layer metal. In particular, in the third embodiment, since the heat treatment is performed after providing the plugging coating layer in order to narrow and close the gap on the crystal structure, the action of the metal for plugging into the gap on the crystal structure is achieved. Can be increased. As a result, it is possible to increase the effect of narrowing and closing the gap on the crystal structure by allowing more metal for filling to enter the gap on the crystal structure. In addition, by introducing the clogging metal into the inside of the gap on the crystal structure, even if the clogging coating layer is removed after that, the clogged portion is scraped off and the effect is reduced. There is no. Note that if the clogging metal can be sufficiently introduced into the gaps on the crystal structure by forming the clogging coating layer in step S323, the heat treatment may be omitted. Further, in this example, after Cr enters the gap on the crystal structure, this Cr is oxidized and expanded, so that the effect of narrowing and closing the gap on the crystal structure is further enhanced. be able to. Further, by removing the plugging coating layer in step S340, it is possible to ensure catalytic activity that promotes the dissociation reaction of hydrogen molecules on the surface of the hydrogen permeable membrane or the binding reaction to hydrogen molecules.

F. Modification of the third embodiment:
(F-1) First modification:
In the third embodiment, various modifications can be made with respect to the order of the steps of heat treatment, oxidation treatment or surface layer removal.

  For example, the heat treatment and the oxidation treatment may be performed simultaneously. That is, heat treatment may be performed in an oxidizing atmosphere to oxidize Cr while promoting the movement of Cr into the gaps on the crystal structure. Further, the oxidation treatment in step S330 may be performed after the surface layer removal in step S340. Alternatively, oxidation treatment and surface layer removal may be performed simultaneously. For example, the removal of the clogging coating layer and the oxidation of Cr that has entered the gaps on the crystal structure can be simultaneously performed by oxygen plasma treatment (or ozone plasma treatment).

  Further, the oxidation treatment in step S330 can be omitted. That is, after performing the heat treatment in step S326, the surface layer may be removed in step S340, and the stacked body may be used as a hydrogen permeable film without performing an oxidation treatment. In this case, in the process of using the manufactured hydrogen permeable membrane, the clogging metal that has entered the metal coating layer 16 is gradually oxidized, and the narrowing and closing of the gap on the crystal structure further proceeds.

  In addition, when performing surface layer removal by physical polishing, even if it remains on the hydrogen permeable film after removing the surface layer as a polishing particle used for polishing, a substance that can exist stably under the conditions of use of the hydrogen permeable film It is desirable to use particles consisting of That is, it is desirable to use particles made of a substance that does not affect the performance of the hydrogen permeable membrane even if it remains on the hydrogen permeable membrane. For example, particles that cause metal diffusion and do not cause a decrease in hydrogen permeation performance, such as particles made of an oxide, may be used. Specifically, particles made of an oxide that fills the gap in the crystal structure, in this embodiment, particles made of chromium oxide may be used as the abrasive particles.

(F-2) Second modification:
In addition to Cr, various elements similar to those of the fourth modification of the first embodiment can be selected as the film forming material constituting the plugging coating layer. What is necessary is just to be able to exist stably under the use condition of a hydrogen permeable film when it becomes an oxide. Also in this case, the gap in the crystal structure can be further narrowed / closed by performing the oxidation treatment in step S330. It should be noted that the reaction that does not impair the hydrogen permeation performance is allowed to be stable under the conditions of use of the hydrogen permeable membrane. For example, when Cr is used as the plugging metal in the third embodiment and the gap on the crystal structure is narrowed and closed with chromium oxide, chromium oxide is transferred from the metal base layer 12 or vanadium oxide. To produce a composite oxide of chromium oxide and vanadium oxide ( V ₂ O ₅ · Cr ₂ O ₃ ). As described above, this composite oxide is a substance having a melting point higher than that of V and difficult to diffuse, and prevents the movement of V and vanadium oxide to the film surface. It is desirable to be done.

(F-3) Third modification:
Alternatively, an element similar to that of the fifth modification of the first embodiment is selected as a film forming material constituting the plugging coating layer, and a nitriding process or a carbonizing process is performed instead of the oxidation process in step S330. Also good. Even in such a configuration, as in the case where the oxidation treatment is performed, the film-forming material is allowed to enter the gap in the crystal structure as a filling material, and then the filling material is expanded by nitriding treatment or carbonization treatment. As a result, the narrowing and closing of the gap on the crystal structure can be further advanced. Alternatively, nitriding or carbonizing may be omitted, and nitriding or carbonizing of the plugging material may be advanced during use of the hydrogen permeable membrane.

(F-4) Fourth modification:
In the third embodiment, a more stable oxide is generated from the metal for packing by forming the plugging coating layer on the Pd layer and then performing an oxidation treatment. On the other hand, the plugging coating layer may be formed using a film forming material that can exist stably under the use conditions of the hydrogen permeable film. For example, an oxide such as chromium oxide, or a nitride or carbide of the element exemplified in the fifth modification of the first embodiment can be used as a film forming material for the filling coating layer. In this case, it is not necessary to separately perform oxidation treatment, nitridation treatment, or carbonization treatment. In this case, when physical polishing is performed as the removal of the surface layer in step S340, particles made of the same material as the film forming material may be used as the polishing particles.

G. Fourth embodiment:
FIG. 5 is a schematic cross-sectional view showing a schematic configuration of the hydrogen permeable membrane of the fourth embodiment. Similar to the hydrogen permeable membrane of the first embodiment, the hydrogen permeable membrane of the fourth embodiment includes a metal base layer 12 made of V or a V alloy and an intermediate layer 14 made of Ta. Further, a metal coating layer 416 that is a layer containing Pd is provided instead of the metal coating layer 16, and a grain boundary coating portion 418 made of chromium oxide is further provided on the metal coating layer 416. The grain boundary coating portion 418 is formed so as to cover the gap on the crystal structure existing on the surface of the metal coating layer 416.

  FIG. 6 is a process diagram showing the method for manufacturing the hydrogen permeable membrane of the fourth embodiment. When manufacturing the hydrogen permeable membrane of the fourth embodiment, the metal base layer 12 is prepared (step S400), and the intermediate layer 14 is formed thereon, as in steps S100 and S110 of the first embodiment. (Step S410). Thereafter, a metal coating layer 416 is formed on the intermediate layer 14 (step S420), and a laminate having a five-layer structure is formed. The metal coating layer 416 is a layer made of Pd alone or a layer made of a Pd alloy containing Pd as a main component.

  Next, the grain boundary coating portion 418 is formed on the metal coating layer 416 (step S425). The grain boundary coating portion 418 is formed using Cr as a film forming material, and is formed so as to cover the gap (mainly the crystal grain boundary) on the crystal structure on the surface of the metal coating layer 416 as described above. A detailed manufacturing method of the grain boundary covering portion 418 will be described later.

  When the grain boundary covering portion 418 is formed in step S425, the stacked body on which the grain boundary covering portion 418 is formed is subjected to the same oxidation treatment as in step S130 (step S430), thereby completing the hydrogen permeable membrane. By performing the oxidation treatment, Cr constituting the grain boundary covering portion 418 is oxidized. Thereby, the grain boundary coating part 418 becomes the grain boundary coating part 418 made of chromium oxide which exists stably even under the use condition of the hydrogen permeable membrane.

  FIG. 7 is a process diagram showing a method of forming the grain boundary covering portion 418 in step S425. In order to form the grain boundary coating part 418, first, the area of the crystal grain boundary vicinity existing on the surface of the metal coating layer 416 is obtained as the area where the grain boundary coating part 418 is to be provided (step S500). That is, since the gap on the crystal structure is mainly a crystal grain boundary, here, the area of the vicinity of the crystal grain boundary is obtained as the area of the peripheral area of the gap on the crystal structure existing on the surface of the metal coating layer 416. . The crystal grain boundaries existing on the surface of the metal coating layer 416 are observed in a linear shape. However, in step S500, the linear crystal grain boundaries are given a predetermined width to form the grain boundary vicinity region. The area covering portion 418 is to be provided. The area of the crystal grain boundary vicinity region may be obtained by actual measurement or may be obtained by estimation. In order to obtain the area in the vicinity of the crystal grain boundary by actual measurement, for example, the surface of the metal coating layer 416 is observed using a scanning electron microscope (SEM), and the area in the vicinity of the crystal grain boundary is determined using the obtained image. Find it. In order to obtain the area of the crystal grain boundary vicinity region by estimation, the relationship between the film forming conditions and the crystal grain boundary vicinity region may be examined in advance. The size of the metal crystal is determined by the energy supplied to the film formation material during film formation. Specifically, the amount of supplied energy is determined by the film forming conditions such as the substrate temperature at the time of film formation and the input energy when the film forming material collides with the substrate. Therefore, if the area near the crystal grain boundary is measured in advance for the metal coating layer deposited under the predetermined film forming conditions, and the relationship between the film forming conditions and the area near the crystal grain boundary is investigated, then Even without actual measurement, the area in the vicinity of the crystal grain boundary can be estimated based on the employed film forming conditions.

  Once the area in the vicinity of the crystal grain boundary is obtained in step S500, the amount of film forming material required for forming the grain boundary covering portion 418 is set (step S510). The film forming material amount set in step S510 covers the area of the crystal grain boundary region with a predetermined thickness based on the area of the crystal grain boundary vicinity region and the atomic radius of Cr as the film forming material. Therefore, it is calculated as the amount (weight) of the film forming material necessary for this. Here, the thickness of the grain boundary covering portion 418 to be formed is more than 1 nm and preferably less than 20 nm, for example, about 5 nm. If the thickness is 1 nm or less, the effect of covering the crystal grain boundary by the grain boundary coating portion 418 may be insufficient. If the thickness is 20 nm or more, the area covered by the grain boundary coating portion 418 becomes too wide, and thus the hydrogen permeable film. This is because the performance of the system may be degraded.

  Thereafter, a Cr layer is formed on the metal coating layer 416 using the amount of film forming material set in step 510 (step S520), whereby the grain boundary coating portion 418 is formed. Here, the film formation in step S520 can be performed by, for example, PVD or CVD. However, when the film formation material activated in this way (high energy state) is supplied onto the substrate, the film formation is performed. The supplied film forming material has a property of preferentially accumulating at a more activated portion on the substrate. On the surface of the metal coating layer 416 serving as a substrate for film formation, it can be said that a gap on the crystal structure such as a crystal grain boundary is a more activated part. Therefore, when the amount of Cr set in step S510 is supplied to the surface of the metal coating layer 416, the Cr is attached preferentially in the vicinity of the gap on the crystal structure, and the grain boundary covering portion 418 covering the region near the crystal grain boundary. Is formed. As described above, in this embodiment, the grain boundary covering portion 418 is limitedly formed in the vicinity of the crystal grain boundary by controlling the film forming material amount to an appropriate value.

  An example of a method of using the amount of film forming material set in step S510 for film formation is a method of actually measuring the film formation amount during film formation. In order to actually measure the amount of film formation, it is only necessary to monitor the film thickness by using a known crystal resonator and measure the weight of the film formed per unit area. Alternatively, when the film formation is performed under the predetermined film formation conditions, a film formation time for the amount of the film formation material used for the film formation to be the calculated film formation material amount is obtained in advance, and the film formation is performed. Under the conditions, film formation may be performed only for the calculated time.

  According to the hydrogen permeable membrane of the fourth embodiment configured as described above, the gap on the crystal structure is narrowed and closed on the metal coating layer 416 by the grain boundary coating portion 418. It is possible to suppress the intrusion of oxygen into the inside through the gap on the crystal structure, and to suppress the arrival of the lower layer metal such as V and its oxide on the surface of the metal coating layer. Therefore, it is possible to suppress the deterioration of the performance of the hydrogen permeable membrane due to the invasion of oxygen and the arrival of the lower layer metal. In the fourth embodiment, since the grain boundary covering portion 418 is formed on the surface of the metal covering layer 416 so as to cover a limited region including a gap on the crystal structure, the hydrogen permeation performance is achieved in other regions. The catalytic activity can be ensured. Therefore, it is possible to suppress a decrease in hydrogen permeation performance due to the provision of the grain boundary covering portion 418. Furthermore, in this embodiment, since the grain boundary covering portion 418 is formed by utilizing the property that the film is preferentially formed on a portion having a high surface activity, it is efficient only by adjusting the amount of film forming material. The gap on the crystal structure can be narrowed and closed easily.

H. Modification of the fourth embodiment:
(H-1) First modification:
After forming the metal coating layer 416 in step S420, a process of enlarging the metal crystal grains in the metal coating layer 416 may be performed. The enlargement of the metal crystal grains can be performed by growing the metal crystal grains by supplying energy to the metal coating layer 416, for example, by heating the metal coating layer 416. Here, it is desirable that the heating for growing crystal grains be performed locally on the metal coating layer 416. If locally heated, the progress of metal diffusion due to heating can be suppressed. In order to locally heat the metal coating layer 416, for example, pulse laser irradiation may be performed on the metal coating layer 416.

  Thus, by enlarging the metal crystal grains constituting the metal coating layer 416 prior to the formation of the grain boundary coating portion 418, the amount of film forming material used for forming the grain boundary coating portion 418 is reduced. be able to. In addition, the film formation time for forming the grain boundary covering portion 418 can be shortened.

(H-2) Second modification:
After forming the metal coating layer 416 in step S420, a process of making the crystal grain boundary on the surface of the metal coating layer 416 concave, that is, a process of deepening the crystal grain boundary may be performed. FIG. 8 schematically shows a state in which the crystal grain boundary on the surface of the metal coating layer 416 is made concave by the concave surface treatment. For example, the grain boundary can be made concave by repeatedly performing oxidation treatment and reduction treatment on the surface of the metal coating layer 416. By repeating the oxidation treatment and the reduction treatment, the metal crystal repeatedly expands and contracts, so that a gap is generated in the metal crystal on the surface of the metal coating layer 416 and the crystal grain boundary becomes concave. Alternatively, the crystal grain boundary may be concaved by performing plasma etching or chemical etching on the surface of the metal coating layer 416.

  If such a concave surface treatment is performed, the crystal grain boundary can be easily observed when measuring the area of the vicinity of the crystal grain boundary in step S500, so that the measurement accuracy can be improved. In addition, since the crystal grain boundary on the surface of the metal coating layer 416 is further activated by the concave surface treatment, film formation of the grain boundary coating part 418 in step S425 becomes easier.

(H-3) Third modification:
In the fourth example, the grain boundary coating portion 418 is directly formed on the metal coating layer 416 in step S425, but a different configuration may be used. For example, a grain boundary covering portion using Cr as a film forming material may be separately produced according to the pattern of the crystal grain boundary on the surface of the metal covering layer 416 observed by SEM, and this may be fixed on the metal covering layer 416. In this case, printing may be performed on a predetermined base material such as polyimide using Cr as a film forming material according to the above pattern, and the printed Cr layer may be transferred onto the metal coating layer 416 and then the substrate may be peeled off. .

(H-4) Fourth modification:
Further, as the film forming material for forming the grain boundary covering portion 418 in step S425, various elements similar to those in the fourth modification of the first embodiment can be selected in addition to Cr. What is necessary is just to be able to exist stably under the use condition of a hydrogen permeable film when it becomes an oxide.

(H-5) Fifth modification:
Or you may select the element similar to the 5th modification of 1st Example as a film-forming material for forming the grain boundary coating | coated part 418 by step S425. In this case, a nitriding process or a carbonizing process may be performed instead of the oxidation process in step S430, or the nitriding or carbonizing of the film forming material may be advanced during use of the hydrogen permeable film. Even in such a configuration, the crystal structure is formed by forming the grain boundary covering portion 418 made of a stable nitride or carbide in the vicinity of the crystal grain boundary on the surface of the metal coating layer 416 as in the case of performing the oxidation treatment. The same effect of narrowing and closing the upper gap can be obtained.

(H-6) Sixth modification:
In the fourth embodiment, the grain boundary coating portion 418 is once formed on the metal coating layer 416 and then the metal constituting the grain boundary coating portion 418 is oxidized. On the other hand, the grain boundary covering portion 418 may be formed on the metal covering layer 416 using a film forming material that can exist stably under the use condition of the hydrogen permeable membrane. For example, the grain boundary covering portion 418 is formed on the metal covering layer 416 by using an oxide such as chromium oxide or the nitride or carbide of the element exemplified in the fifth modification of the first embodiment as a film forming material. Can do. In this case, it is not necessary to separately perform oxidation treatment, nitridation treatment, or carbonization treatment. Further, in this case, in step S510, film formation necessary for covering the area of the crystal grain boundary region with a predetermined thickness based on the area of the crystal grain boundary vicinity region and the lattice constant of the film forming material. What is necessary is just to calculate the quantity of material.

(H-7) Seventh modification:
In the fourth embodiment, the grain boundary coating portion 418 is formed on the metal coating layer 416, but the same structure as the grain boundary coating portion 418 is added to the grain boundary coating portion 418 or the grain boundary coating portion 418. Instead of this, it may be provided on the lower layer of the metal coating layer 416. Since the movement of oxygen, constituent metals, or oxides in the hydrogen permeable membrane is mainly performed through the gaps in the crystal structure, the surface of any layer constituting the hydrogen permeable membrane is the same as in the fourth embodiment. By providing the grain boundary covering portion, the above movement can be suppressed.

For example, a structure similar to the grain boundary covering portion 418 can be provided on the metal base layer 12. In this case, after forming the metal base layer 12 in step S400, the same grain boundary covering portion as that in the fourth embodiment may be formed on the metal base layer 12 prior to the formation of the intermediate layer. With such a configuration, when oxygen enters the inside of the hydrogen permeable membrane, oxidation of the constituent metals of the metal base layer 12 due to oxygen entering the metal base layer 12 can be suppressed.

  Similarly, after forming the intermediate layer 14 in step S410, prior to the formation of the metal coating layer 416, a grain boundary coating portion similar to that of the fourth embodiment may be formed on the intermediate layer 14. In this case, when oxygen enters the inside of the hydrogen permeable membrane, the arrival of oxygen to the metal base layer 12 through the intermediate layer 14 is suppressed, and the oxidation of the metal constituting the metal base layer 12 is suppressed. Can do. In addition, the metal constituting the metal base layer 12 and the oxide of the metal constituting the metal base layer 12 reach the surface of the hydrogen permeable membrane via the intermediate layer 14 to reduce the performance of the hydrogen permeable membrane. Can be suppressed.

I. Check the effect:
The result of producing the hydrogen permeable membrane of the fourth example and confirming the effect of the grain boundary covering portion 418 suppressing the movement of the lower layer metal to the surface is shown below. Here, the hydrogen permeable membranes of Experimental Examples 1 and 2 corresponding to the fourth example and the hydrogen permeable membrane of the comparative example were produced. Specific configurations of the hydrogen permeable membranes of Experimental Examples 1 and 2 and Comparative Example used are shown below. Here, the hydrogen permeable membrane of the comparative example is different from the hydrogen permeable membranes of Experimental Examples 1 and 2 in that the grain boundary coating portion 418 is not provided.

Experimental Example 1; metal base layer 12 (V layer having a thickness of 100 μm), intermediate layer 14 (Ta layer having a thickness of 0.1 μm), metal coating layer 416 (Pd layer having a thickness of 1 μm), grain boundary coating portion 418 ( 5 nm thick Cr layer):
Experimental Example 2: Metal base layer 12 (V layer having a thickness of 100 μm), intermediate layer 14 (Ta layer having a thickness of 0.1 μm), metal coating layer 416 (Pd layer having a thickness of 1 μm), grain boundary coating portion 418 ( Al layer with a thickness of 5 nm):
Comparative example: metal base layer (V layer having a thickness of 100 μm), intermediate layer (Ta layer having a thickness of 0.1 μm), metal coating layer (Pd layer having a thickness of 1 μm):

  In addition, about the hydrogen permeable film of Experimental example 1, 2, after forming the grain boundary coating | coated part 418 of the above-mentioned thickness, it oxidized in 400 degreeC and conditions for 6.5 hours in the air. FIG. 9 is an explanatory view showing an SEM image of the surface of Experimental Example 1 observed. FIG. 9A shows the state of the surface of the metal coating layer 416 formed in step S420. In the surface of the metal coating layer 416, a portion corresponding to a contact point at which three or more metal crystals are in contact with each other as a fine hole formed in the metal coating layer 416 is a black dot in FIG. 9A. Observed. FIG. 9B shows the surface after the grain boundary coating portion 418 made of Cr is formed on the metal coating layer 416 and further subjected to oxidation treatment. In FIG. 9B, it is observed that white fine particles considered to be chromium oxide are present on the surface of the metal coating layer 416 and the black dot-shaped holes are covered.

  In order to investigate the effect of the grain boundary covering portion 418 using the hydrogen permeable membranes of the above experimental examples 1 and 2 and the comparative example, each hydrogen permeable membrane was subjected to conditions (more oxidized than the conditions for using normal hydrogen permeable membranes). Comparison was made under easy conditions. Specifically, each hydrogen permeable membrane was treated in air at 600 ° C. for 6.5 hours. The SEM image of the surface of each hydrogen permeable membrane after a process is shown in FIG.

  FIGS. 10A, 10B, and 10C show the surface states of the hydrogen permeable membranes of Experimental Examples 1 and 2 or Comparative Example, respectively. As shown in FIGS. 10A and 10B, in the hydrogen permeable membranes of Experimental Examples 1 and 2, the surface of the metal coating layer 416 is slightly lower (at about 5% of the entire surface of the metal coating layer 416). It was observed that metal V or vanadium oxide was ejected from the lower layer and covered the surface. On the other hand, as shown in FIG. 10C, in the hydrogen permeable membrane of the comparative example, the lower layer metal is in a wider range on the surface of the metal coating layer (about 60% of the total area of the surface of the metal coating layer 126). It was observed that V or vanadium oxide was ejected from the lower layer and covered the surface. Thus, it has been shown that by providing the grain boundary coating portion 418, the ejection of the lower layer metal in the metal coating layer can be suppressed extremely effectively.

J. et al. Equipment using hydrogen permeable membrane:
(J-1). Hydrogen extraction equipment:
FIG. 11 is a schematic cross-sectional view showing the configuration of a hydrogen extraction device 20 using the hydrogen permeable membrane (hereinafter referred to as hydrogen permeable membrane 10) of any of the first to fourth embodiments. The hydrogen extraction apparatus 20 has a structure in which a plurality of hydrogen permeable membranes 10 are stacked. FIG. 11 shows only the configuration relating to the stacking of the hydrogen permeable membranes 10. In the hydrogen extraction device 20, a support portion 22 that is joined to the outer peripheral portion of the hydrogen permeable membrane 10 is disposed between the stacked hydrogen permeable membranes 10, and a predetermined portion is provided between the hydrogen permeable membranes 10 by the support portion 22. A space is formed. The support portion 22 may be bonded to the hydrogen permeable membrane 10 and has sufficient rigidity. For example, by forming with a metal material such as stainless steel (SUS), it is possible to easily join the hydrogen permeable membrane 10 which is a metal layer.

  The predetermined spaces formed between the hydrogen permeable membranes 10 alternately form hydrogen-containing gas paths 24 and purge gas paths 26. A hydrogen-containing gas to be subjected to hydrogen extraction is supplied to each hydrogen-containing gas passage 24 from a hydrogen-containing gas supply unit (not shown). A purge gas having a sufficiently low hydrogen concentration is supplied to each purge gas passage 26 from a purge gas supply unit (not shown). Hydrogen in the gas supplied to the hydrogen-containing gas passage 24 is extracted from the hydrogen-containing gas by permeating the hydrogen permeable membrane 10 toward the purge gas passage 26 according to the hydrogen concentration difference.

  According to such a hydrogen extraction apparatus 20, since the lowering of the performance due to the oxidation of the lower layer metal of the hydrogen permeable membrane or the movement of the lower layer metal to the surface is suppressed, the hydrogen extraction performance of the entire hydrogen extraction apparatus 20 is suppressed. Can be prevented.

(J-2). Fuel cell:
FIG. 12 is a schematic cross-sectional view showing an example of the configuration of a fuel cell using the hydrogen permeable membrane 10. FIG. 12 shows a single cell 30. A fuel cell is formed by stacking a plurality of single cells 30.

  The single cell 30 includes a hydrogen permeable membrane 10, an electrolyte layer 32 formed on one surface of the hydrogen permeable membrane 10, and a cathode electrode 34 formed on the electrolyte layer 32. 31 is provided. The single cell 30 further includes two gas separators 36 and 37 that sandwich the MEA 31 from both sides. Between the hydrogen permeable membrane 10 and the gas separator 36 adjacent thereto, a single-cell fuel gas flow path 38 through which a hydrogen-containing fuel gas passes is formed. In addition, between the cathode electrode 34 and the gas separator 37 adjacent thereto, an in-single cell oxidizing gas passage 39 through which an oxidizing gas containing oxygen passes is formed.

The electrolyte layer 32 is a layer made of a solid electrolyte having proton conductivity, for example, a BaCeO ₃ or SrCeO ₃ ceramic proton conductor. The electrolyte layer 32 can be formed by generating the solid oxide on the hydrogen permeable membrane 10 by a method such as PVD or CVD. Thus, by forming the electrolyte layer 32 on the hydrogen permeable membrane 10 which is a dense metal film, the electrolyte layer 32 can be made thinner, and the membrane resistance of the electrolyte layer 32 can be further reduced. Thereby, it becomes possible to generate electric power at about 200 to 600 ° C., which is lower than the operating temperature of the conventional solid oxide fuel cell.

  The cathode electrode 34 is a layer having catalytic activity that promotes an electrochemical reaction, and may be formed of, for example, a porous Pt layer made of noble metal Pt. In the single cell 30, a current collector having electrical conductivity and gas permeability may be further provided between the cathode electrode 34 and the gas separator 37 or between the hydrogen permeable membrane 10 and the gas separator 36.

  The gas separators 36 and 37 are gas-impermeable members formed of a conductive material such as carbon or metal. On the surfaces of the gas separators 36 and 37, a predetermined uneven shape for forming the single-cell fuel gas flow path 38 or the single-cell oxidizing gas flow path 39 is formed.

  According to such a fuel cell, since the lowering of the performance due to the oxidation of the lower layer metal of the hydrogen permeable membrane or the movement of the lower layer metal to the surface is suppressed, the lowering of the performance of the entire fuel cell can be prevented. .

  In the hydrogen permeable membrane provided in the fuel cell shown in FIG. 12, unlike the hydrogen permeable membrane 10 shown in FIG. 1, the metal coating layer and the intermediate layer are not provided on the surface in contact with the electrolyte layer 32. Is also possible.

K. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

K1. Modification 1:
Each layer constituting the hydrogen permeable membrane may be formed of a metal different from the first to fourth embodiments. For example, in the embodiment, the metal base layer 12 is formed of a metal having V or V as a main component, but may be formed of a metal (including a simple substance) containing another group 5 metal.

  In the embodiment, the intermediate layer 14 is made of Ta. However, if the metal diffusion between the metal base layer 12 and the metal coating layer 16 can be suppressed, the intermediate layer 14 is formed of different hydrogen permeable metals. You may do it. In particular, the metal constituting the intermediate layer 14 is preferably formed of a metal having a higher melting point than the metal base layer 12 and the metal coating layer 16 (hereinafter referred to as a refractory metal). Since a metal having a high melting point generally has a property that it is difficult to diffuse the metal, the effect of preventing metal diffusion can be enhanced by forming the intermediate layer 14 with a high melting point metal. For example, in addition to Ta, niobium (Nb), which is the same Group 5 metal, is preferable because it has sufficient hydrogen permeation performance and is a high melting point metal. Further, the intermediate layer 14 may be formed of an alloy containing Ta or Nb, which is a refractory metal, as a main metal, in addition to a metal layer made of Ta or Nb alone.

K2. Modification 2:
In the first to fourth embodiments, the intermediate layer 14 is provided between the metal base layer 12 and the metal coating layer, but the intermediate layer 14 may not be provided. That is, a metal coating layer containing Pd may be directly formed on the metal base layer 12 made of a Group 5 metal such as V or an alloy thereof. Even in such a case, the same effect as the embodiment can be obtained by narrowing and closing the gap on the crystal structure in the metal coating layer.

K3. Modification 3:
In the hydrogen permeable membranes of the first to fourth embodiments already described, the hydrogen permeable membrane is a self-supporting membrane of a metal thin film having hydrogen permeability, but the hydrogen permeable metal is formed on a porous substrate having gas permeability. A hydrogen permeable membrane may be formed by supporting. That is, a metal layer laminated in the order of a metal coating layer, an intermediate layer, a metal base layer, an intermediate layer, and a metal coating layer may be sequentially formed on a thin plate-like porous body to form a hydrogen permeable membrane. Thus, the hydrogen permeable membrane carry | supported on the porous base material can be used instead of the hydrogen permeable membrane 10 of an Example in the hydrogen extraction apparatus shown in FIG. 11, for example. For example, when the first embodiment is applied to the above configuration, a hydrogen permeable film is formed on the porous body and then the whole is oxidized to narrow and close the gap on the crystal structure in the metal coating layer. You can do it.

It is a cross-sectional schematic diagram showing schematic structure of the hydrogen permeable film of 1st Example. It is process drawing showing the manufacturing method of the hydrogen permeable film of 1st Example. It is process drawing showing the manufacturing method of the hydrogen permeable film of 2nd Example. It is process drawing showing the manufacturing method of the hydrogen permeable film of 3rd Example. It is a cross-sectional schematic diagram showing schematic structure of the hydrogen permeable film of 4th Example. It is process drawing showing the manufacturing method of the hydrogen permeable film of 4th Example. It is process drawing showing the method of forming a grain boundary coating | coated part. It is a schematic diagram showing the mode of concave processing. It is explanatory drawing which shows the SEM image which observed the surface of Experimental example 1. FIG. It is explanatory drawing which shows the result of having investigated the effect of the grain boundary coating | coated part. It is a cross-sectional schematic diagram showing the structure of a hydrogen extraction apparatus. It is a cross-sectional schematic diagram showing an example of a structure of a fuel cell.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Hydrogen permeable membrane 12 ... Metal base layer 14 ... Intermediate | middle layer 16,416 ... Metal coating layer 20 ... Hydrogen extraction apparatus 22 ... Supporting part 24 ... Hydrogen-containing gas path 26 ... Purge gas path 30 ... Single cell 31 ... MEA
32 ... Electrolyte layer 34 ... Cathode electrode 36, 37 ... Gas separator 38 ... Single-cell fuel gas flow path 39 ... Single-cell oxidizing gas flow path 418 ... Grain boundary coating part

Claims (30)

A method for producing a hydrogen permeable membrane that selectively permeates hydrogen,
(A) a first step of preparing a metal base layer containing a Group 5 metal;
(B) When forming a multilayer structure by sequentially forming a predetermined metal layer on one or both surfaces of the metal base layer , oxide, nitride or carbide is added in addition to palladium (Pd). A second step of forming a metal coating layer containing a second component that can be formed on the surface of the multilayer structure;
(C) a third step of narrowing or closing a gap in a crystal structure including a crystal grain boundary in the metal coating layer by oxidizing, nitriding or carbonizing the second component ;
A method for producing a hydrogen permeable membrane comprising: A method for producing a hydrogen permeable membrane according to claim 1 ,
The second component is selected from chromium (Cr), aluminum (Al), silicon (Si), titanium (Ti), iron (Fe), copper (Cu), molybdenum (Mo), and zirconium (Zr). Element,
The third step is a step of oxidizing the second component. A method for manufacturing a hydrogen permeable membrane. A method for producing a hydrogen permeable membrane according to claim 1 ,
The second component is an element selected from chromium (Cr), aluminum (Al), silicon (Si), titanium (Ti), iron (Fe),
The third step is a step of nitriding the second component. A method for manufacturing a hydrogen permeable membrane. A method for producing a hydrogen permeable membrane according to claim 1 ,
The second component is an element selected from silicon (Si) and titanium (Ti),
The third step is a step of carbonizing the second component. A method for producing a hydrogen permeable membrane. A method for producing a hydrogen permeable membrane according to any one of claims 1 to 4 ,
The metal coating layer formed in the second step contains Pd as a whole, and only a limited region including the surface of the metal coating layer further includes the second component. . A method for producing a hydrogen permeable membrane according to any one of claims 1 to 5 , further comprising:
(D) A method for producing a hydrogen permeable membrane, comprising a fourth step of forming a palladium layer on the metal coating layer before or after the third step. A method for producing a hydrogen permeable membrane that selectively permeates hydrogen,
(A) a first step of preparing a metal base layer containing a Group 5 metal;
(B) a second component capable of forming an oxide, nitride, or carbide when a predetermined metal layer is sequentially formed on one or both surfaces of the metal base layer to form a multilayer structure; And a second step of forming a metal coating layer provided in addition to palladium (Pd) on the surface of the multilayer structure. A method for producing a hydrogen permeable membrane that selectively permeates hydrogen,
(A) a first step of preparing a metal base layer containing a Group 5 metal;
(B) When a predetermined metal layer is sequentially formed on one or both surfaces of the metal base layer to form a multilayer structure, in addition to palladium (Pd) , at the use temperature of the hydrogen permeable membrane a first metallization layer Ru consists compound containing the second component in an amount exceeding a solid solubility limit, and a second step of forming on the surface of the multilayer structure,
(C) In the metal coating layer, by performing a heat treatment for precipitating the second compound having a higher content ratio of the second component than the first compound in a gap in a crystal structure including a crystal grain boundary , A third step of narrowing or closing the gap;
A method for producing a hydrogen permeable membrane comprising: The method for producing a hydrogen permeable membrane according to claim 8 , further comprising:
(D) A method for producing a hydrogen permeable membrane, comprising a fourth step of oxidizing, nitriding, or carbonizing the second element in the deposited second compound together with or after the third step. . The method for producing a hydrogen permeable membrane according to claim 8 or 9 , further comprising:
(E) A method for producing a hydrogen permeable membrane, comprising a fifth step of forming a palladium layer on the metal coating layer after the third step. A method for producing a hydrogen permeable membrane that selectively permeates hydrogen,
(A) a first step of preparing a metal base layer containing a Group 5 metal;
(B) When a predetermined metal layer is sequentially formed on one or both surfaces of the metal base layer to form a multilayer structure, in addition to palladium (Pd), at the use temperature of the hydrogen permeable membrane And a second step of forming a metal coating layer containing a second component in an amount exceeding the solid solution limit on the surface of the multilayer structure. A method for producing a hydrogen permeable membrane that selectively permeates hydrogen,
(A) a first step of preparing a metal base layer containing a Group 5 metal;
(B) When forming a multilayer structure by sequentially forming predetermined metal layers on one or both surfaces of the metal base layer, a metal coating layer containing palladium (Pd) is formed on the surface of the multilayer structure. A second step of forming
(C) A film is formed on the metal coating layer using a predetermined film forming material to form a plugging coating layer that covers the metal coating layer. A third step of narrowing or closing the gap in the crystal structure including the boundary;
And (d) manufacturing the hydrogen permeable membrane and a fourth step of removing the first filling coating layer formed on said metallized layer. The method for producing a hydrogen permeable membrane according to claim 12 , further comprising:
(E) A method for producing a hydrogen permeable membrane, comprising a fifth step of oxidizing, nitriding or carbonizing the film forming material constituting the plugging coating layer before or after the fourth step. A method for producing a hydrogen permeable membrane according to claim 12 ,
The film forming material used in the third step is a material capable of forming an oxide,
The fourth step is a method of removing the plugging coating layer by dry etching using oxygen plasma or ozone plasma. A method for producing a hydrogen permeable membrane according to claim 13 ,
The fourth step is a method of removing the plugging coating layer by physical polishing using abrasive particles made of oxide, nitride or carbide generated from the film forming material. A method for producing a hydrogen permeable membrane according to claim 12 ,
The third step is a method of forming the plugging coating layer using a film forming material that can stably exist under the use condition of the hydrogen permeable membrane. A method for producing a hydrogen permeable membrane according to claim 16 ,
The film forming material is an oxide, nitride, or carbide. The method for producing a hydrogen permeable membrane according to claim 16 or 17 ,
In the fourth step, the surface layer is removed by physical polishing using abrasive particles made of the film forming material used in the third step. The method for producing a hydrogen permeable membrane according to any one of claims 12 to 18 , further comprising:
(F) After the third step, prior to the fourth step, a temperature lower than the melting point of the metal constituting the hydrogen permeable membrane with respect to the metal coating layer having the plugging coating layer made of the element. A method for producing a hydrogen permeable membrane, comprising a sixth step of performing a heat treatment in the step. A method for producing a hydrogen permeable membrane that selectively permeates hydrogen,
(A) a first step of preparing a metal base layer containing a Group 5 metal;
(B) When forming a multilayer structure by sequentially forming predetermined metal layers on one or both surfaces of the metal base layer, a metal coating layer containing palladium (Pd) is formed on the surface of the multilayer structure. A second step of forming
(C) forming a crystal grain boundary covering portion that covers only a limited region including the crystal grain boundary existing on the surface of the metal coating layer on the surface of the metal coating layer; A third step of narrowing or closing a gap in a crystal structure including a grain boundary;
A method for producing a hydrogen permeable membrane comprising: The method for producing a hydrogen permeable membrane according to claim 20 , further comprising:
(D) A method for producing a hydrogen permeable membrane, comprising a fourth step of oxidizing, nitriding or carbonizing the film forming material constituting the crystal grain boundary covering portion. A method for producing a hydrogen permeable membrane according to claim 21 ,
The crystal grain boundary covering portion is formed using an element selected from chromium (Cr), silicon (Si), and aluminum (Al) as a film forming material,
The fourth step is a step of oxidizing the film forming material. A method for manufacturing a hydrogen permeable membrane. A method for producing a hydrogen permeable membrane according to claim 20 ,
The third step is a method for producing a hydrogen permeable film, wherein the crystal grain boundary covering portion is formed using a film forming material that can stably exist under the use condition of the hydrogen permeable film. A method for producing a hydrogen permeable membrane according to claim 23 ,
The film forming material is an oxide, nitride, or carbide. A method for producing a hydrogen permeable membrane according to claim 24 ,
The crystal grain boundary covering portion is formed using an oxide selected from chromium oxide, silicon oxide, and aluminum oxide as a film forming material. A method for producing a hydrogen permeable membrane according to any one of claims 20 to 25 , comprising:
The third step includes
(C-1) A film formation area acquisition step of measuring or estimating the area of the vicinity of the crystal grain boundary existing on the surface of the metal coating layer as the area to be formed;
(C-2) Based on the measured or estimated area and the atomic radius or lattice constant of the film forming material used for forming the crystal grain boundary covering portion, the amount of the film forming material to be used for film forming is determined. A film forming material amount setting step to be set;
(C-3) A film forming step of forming a film on the metal coating layer using the film forming material in an amount set in the film forming material amount setting step. The method for producing a hydrogen permeable membrane according to any one of claims 20 to 26 , further comprising:
(E) Prior to the third step, the method for producing a hydrogen permeable membrane includes a fifth step of enlarging the crystal grains on the surface of the metal coating layer. The method for producing a hydrogen permeable membrane according to any one of claims 20 to 26 , further comprising:
(F) Prior to the third step, a method for producing a hydrogen permeable membrane includes a sixth step of making the crystal grain boundary on the surface of the metal coating layer concave. A hydrogen permeable membrane that selectively permeates hydrogen,
Claims 1 to 28 hydrogen permeable membrane produced by the method according to any one. A hydrogen permeable membrane that selectively permeates hydrogen,
A metal base layer containing a Group 5 metal;
A metal coating layer provided on at least one surface of the hydrogen permeable membrane and comprising palladium (Pd);
Formed by laminating a plurality of layers including
The metal coating layer includes an element that can be an oxide, nitride, or carbide, or an oxide, nitride, or carbide at a crystal grain boundary included in the metal coating layer.

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