JP2009045539A - Hydrogen-permeable membrane and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a thin hydrogen-permeable membrane excellent in hydrogen permeability while preventing formation of pin holes. <P>SOLUTION: The method for manufacturing a hydrogen permeability involves the steps of: forming a first Pd layer or Pd alloy layer on a substrate by a sputtering method (S2); washing the first Pd layer or Pd alloy layer (S3); stacking a second Pd layer or Pd alloy layer on the first washed Pd layer or Pd alloy layer by a sputtering method (S4); separating the a united structural film having the first Pd layer or Pd alloy layer and the second Pd layer or Pd alloy layer from the substrate (S6); and heating the united structural film at a temperature of 400 to 1,200°C in vacuum or inert atmosphere (S7). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hydrogen permeable membrane for selectively permeating and separating hydrogen gas from a mixed gas containing hydrogen gas, and a method for manufacturing the same.

  Conventionally, a hydrogen permeable membrane using a Pd film or a Pd alloy film has been used in an apparatus for purifying high purity hydrogen used as a reducing gas in a semiconductor silicon manufacturing process. In recent years, fuel cells have attracted attention as a low pollution energy, and a hydrogen permeable membrane using a Pd membrane or a Pd alloy membrane is applied to an apparatus for purifying and separating hydrogen gas used as fuel for the fuel cell. Is being considered.

  The hydrogen permeability of the Pd film and the Pd alloy film is such that only hydrogen gas among various gas components dissolves as hydrogen atoms in the film, diffuses to the opposite side of the film, and the hydrogen atoms are bonded to each other. It is expressed by returning to the hydrogen molecule again.

The hydrogen permeation flow rate J (molH ₂ · m ^-2 · sec ^-1 ) of the hydrogen permeable membrane is the hydrogen permeation coefficient φ (molH ₂ · m ^-1 · sec ^-1 · Pa ^-0.5 ), the hydrogen partial pressure Ph on the pressure side Using (Pa), the hydrogen partial pressure Pl (Pa) on the permeate side, and the film thickness d (m) of the hydrogen permeable membrane, the following expression is used.

J = φ · (Ph ^0.5 −Pl ^0.5 ) / d
From this equation, it is understood that the hydrogen permeation flow rate J increases as the film thickness decreases. For example, under the conditions where the temperature is 400 ° C., the hydrogen partial pressure on the pressure side is 0.2 MPa, and the hydrogen partial pressure on the permeate side is normal pressure, the hydrogen permeation flow rate J of the Pd film having a film thickness of 20 μm is 20 mL / (min · cm ²⁾ if it was, when the film thickness 1μm 1/20, hydrogen permeation flux J is increased up to 20 times ^{400mL / (min · cm 2)} . Here, since the amount of Pd used is proportional to the film thickness, the amount of Pd used is 1/20. For this reason, reducing the film thickness is advantageous in terms of both hydrogen permeability and material cost of the hydrogen permeable membrane.

  However, when the film thickness is reduced, there is a problem that pinhole defects increase and the selection function of the hydrogen permeable film is impaired.

  On the other hand, in Patent Document 1, from the Pd alloy ingot obtained by the floating cold crucible melting method, the inclusions in the ingot causing the pinhole are removed, and the ingot is forged and rolled, A method for obtaining a hydrogen permeable membrane is disclosed. However, there is a limit to the film thickness of the hydrogen permeable film obtained by rolling, and it is difficult to obtain a hydrogen permeable film having a film thickness of 5 μm or less and no leakage.

  Patent Document 2 discloses a method for producing a hydrogen permeable membrane in which a plurality of Ta foils are stacked, sandwiched by Pd foils from both sides, joined by hot pressing, and then rolled. In this method, even if pin holes are generated in the Ta foils by overlapping the Ta foils, the purity of hydrogen that permeates is improved by reducing the possibility of leakage as a whole Ta foil. However, when joining using a hot press, defects that cause leakage are easily introduced, and since the film is obtained by rolling, the film thickness is similarly 5 μm or less and there is no leakage. It is difficult to obtain a hydrogen permeable membrane. In addition, when the diffusion bonding layer of Ta and Pd is thick, there is a problem that hydrogen permeability cannot be maintained high.

On the other hand, in Patent Document 3, a Pd alloy having a film thickness of 5 μm or less, which is difficult to produce by rolling, is formed by forming a Pd film or a Pd alloy film on a substrate using a sputtering method and peeling the film from the substrate. Obtaining a membrane is disclosed. However, in order to suppress the occurrence of pinholes, it is required to have a high degree of cleanness in the manufacturing process such as cleaning and handling of the substrate used for sputtering. If such cleanliness is insufficient, the occurrence of pinholes increases. Therefore, there is a problem that it takes time to manage quality in the production of the hydrogen permeable membrane.
JP 2006-175379 A JP 2004-202479 A JP 2005-218963 A

  The present invention effectively suppresses the generation of pinholes without requiring a high degree of cleaning when a hydrogen permeable membrane having a thin film thickness and good hydrogen permeability is obtained using a sputtering method. It is an object to provide a method.

  As a result of intensive studies on such problems, the present inventor formed a first layer on a substrate when forming a Pd film or a Pd alloy film obtained by a sputtering method, By cleaning the first layer, the foreign matter caused by the formation of the pinhole of the first layer due to the substrate is removed, and then the second layer is laminated to form the pinhole of the first layer. It was found that a Pd film or a Pd alloy film having no pinhole as a whole can be obtained by sealing and inhibiting the formation of pinholes in the second layer, and the present invention was completed based on this finding. .

  The method for producing a hydrogen permeable membrane according to the present invention includes a step of forming a first Pd layer or a Pd alloy layer on a substrate by a sputtering method, a step of cleaning the first Pd layer or a Pd alloy layer, A step of laminating a second Pd layer or Pd alloy layer by a sputtering method on the cleaned first Pd layer or Pd alloy layer, the first Pd layer or Pd alloy layer, and the second Pd layer A step of peeling a monolithic structure film having a layer or a Pd alloy layer from the substrate, and a step of heat-treating the monolithic structure film at a temperature of 400 to 1200 ° C. in a vacuum or in an inert atmosphere.

  Preferably, the cleaning step includes at least one of gas spraying, brushing and ultrasonic cleaning.

  Before the step of forming the first Pd layer or the Pd alloy layer, there is a step of cleaning the substrate.

  The Pd alloy layer preferably contains at least one selected from the group consisting of a Pd—Ag alloy, a Pd—Cu alloy, a Pd—Y alloy, and a Pd—rare earth metal alloy.

  Moreover, it is preferable to form a frame body on the outer periphery of the upper surface of the second Pd layer or Pd alloy layer.

  The thickness of the second Pd layer or Pd alloy layer is preferably 0.1 μm or more.

  According to the method of manufacturing a hydrogen permeable membrane according to the present invention, pinholes formed in the first Pd layer or Pd alloy layer are sealed with the stacked second Pd layer or Pd alloy layer, and As the integral structure film of the first layer and the second layer, a hydrogen permeable film having no pinhole defect is obtained.

  According to the present invention, it is possible to obtain a hydrogen permeable film of 5 μm or less having no defects due to pinholes and good hydrogen permeability by sputtering, without requiring a high degree of cleanness in the production process. Therefore, it is possible to efficiently provide a hydrogen permeable membrane, which is a material for an apparatus for purifying and separating hydrogen, at low cost.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, an embodiment of the method for producing a hydrogen permeable membrane of the present invention includes a substrate cleaning step (S1), a sputtering step (S2), a membrane cleaning step (S3), a sputtering lamination step (S4), a frame. It consists of a body formation process (S5), a peeling process (S6), and a heat treatment process (S7). FIG. 2 schematically shows the formation process of the hydrogen permeable membrane.

  First, in the substrate cleaning step (S1), the substrate 1 for forming the Pd layer or the Pd alloy layer is prepared and cleaned (see FIG. 2A).

  As the material of the substrate 1, a strong adhesive force is obtained to such an extent that the first Pd layer or the Pd alloy layer 2 does not spontaneously peel during the film formation in the sputtering step (S2), and the Pd on the substrate in the peeling step (S16). Any material can be used as long as the layer / Pd alloy layer can be peeled off. For example, a smooth glass substrate, or a metal plate or Si wafer whose surface is coated with oxide or nitride can be used.

  The substrate 1 is charged with foreign matter electrostatically on the surface thereof. In the sputtering step (S2), since it is not necessary to completely suppress the occurrence of pinholes in the Pd layer or Pd alloy layer to be formed, the step is performed in a special facility such as a clean room that suppresses dust. It is not necessary to perform this step, and when a clean substrate can be prepared, this step can be omitted.

  Examples of the method for cleaning the substrate 1 include ultrasonic cleaning and vapor cleaning. Alternatively or additionally, the substrate 1 may be sputter etched in a sputtering apparatus. By cleaning the substrate 1, it is possible to eliminate the cause of the pinhole generation caused by the substrate 1.

  Similarly, since it is not necessary to completely suppress the generation of pinholes in the sputtering step (S2), when attaching the substrate 1 to the sputtering apparatus after cleaning, this operation is performed with a special room such as a clean room for suppressing dust. There is no need to do it in the facility.

  Next, in the sputtering step (S2), a first Pd layer or a Pd alloy layer 2 is formed on the substrate by sputtering using a sputtering apparatus equipped with the cleaned substrate 1 (see FIG. 2B). ).

  Examples of the material of the first Pd layer or the Pd alloy layer 2 include, but are not limited to, pure Pd, Pd—Ag alloy, Pd—Cu alloy, Pd—Y alloy, and Pd—rare earth metal alloy.

  Further, the sputtering conditions may follow known conditions for forming a Pd layer or a Pd alloy layer.

  Since the first Pd layer or the Pd alloy layer 2 is formed with pinholes due to foreign matters adhering to the substrate 1, it is preferable that the total thickness of the monolithic structure film is thin. Specifically, it is made thinner than the second Pd layer or the Pd alloy layer 3. However, if it is less than 0.05 μm, it will be damaged in the next film cleaning step (S3).

  Next, in the film cleaning step (S3), cleaning is performed using at least one of gas spraying, brushing, and ultrasonic cleaning on the first Pd layer or the Pd alloy layer 2 that remains attached to the substrate 1. . The gas injection may be performed using an inert compressed gas such as dry compressed air or nitrogen gas, or an alternative chlorofluorocarbon gas spray. The brushing may be performed by wiping the film surface with a static elimination brush, a nonwoven fabric, a dustless cloth, or the like. The ultrasonic cleaning may be performed using ethanol, acetone, ion-exchanged water, or the like. Further, gas spraying, brushing, ultrasonic cleaning and the like may be combined in a timely manner. In this step, the foreign matter adhering to the substrate 1 and the film-like first Pd layer or Pd alloy layer 2 is removed.

  If the film cleaning step (S3) is not performed, the second layer is also formed with foreign matter interposed, and the second layer is dropped in the peeling step (S6), and pinholes are formed throughout the hydrogen permeable membrane 8 (described in FIG. 2 (l)). Will be formed.

  Here, since the first Pd layer or the Pd alloy layer 2 is conductive, electrostatic reattachment of the removed foreign matter is suppressed, and the foreign matter is removed more efficiently than the insulating substrate cleaning step (S1). can do. When the foreign matter is removed, a pinhole 2a is generated in the first Pd layer or Pd alloy layer 2 and the substrate 1 is exposed (see FIG. 2C). However, in the sputtering lamination step (S4), when the second Pd layer or the Pd alloy layer 3 is formed, the foreign matter causing the pinhole is removed and hardly reattached. The foreign matter is hardly present on the surface of the first layer.

  Next, the second Pd layer or the Pd alloy layer 3 is laminated in the sputtering lamination step (S4). At this time, the pinhole 2a is sealed when the second Pd layer or the Pd alloy layer 3 is formed (see FIG. 2D).

  As in the sputtering step (S2), the Pd layer or the Pd alloy layer 3 laminated in the sputtering lamination step (S4) may be pure Pd, Pd—Ag alloy, Pd—Cu alloy, and Pd—rare earth metal alloy. However, it is not limited to these. Further, the sputtering conditions may follow known conditions for forming a Pd layer or a Pd alloy layer.

  The total thickness of the Pd layer or the Pd alloy layers 2 and 3 obtained in the sputtering step (S2) and the sputtering lamination step (S4) is 0.15 to 5 μm. If the thickness exceeds 5 μm, hydrogen permeability is insufficient in the finally obtained hydrogen permeable membrane 8 (described in FIG. 2 (l)). On the other hand, if the total thickness is less than 0.15 μm, it is difficult to peel the integral structure film 4 (described in FIG. 2 (i)) from the substrate 1. In addition, when there exists a means which enables handling, such as peeling from the board | substrate 1, without damaging a thin film, it may be less than 0.15 micrometer.

  The thickness of the second Pd layer or Pd alloy layer 3 in this sputtering lamination step (S4) is preferably 0.1 μm or more. If it is less than 0.1 μm, the film thickness of the pinhole sealing portion of the first Pd layer or the Pd alloy layer 2 is less than 0.1 μm, and the integrated structure film 4 (described in FIG. 2F) is not damaged. It becomes difficult to peel. Due to the damage, the pinhole penetrates through the entire thickness of the monolithic structure film 4 and causes a leak defect.

  Next, in the frame forming step (S5), the metal mask 5 is placed on the second Pd layer or Pd alloy layer 3 to perform masking (see FIG. 2E), and this second Pd layer or Pd A metal film is formed on the outer peripheral portion of the upper surface of the alloy layer 3 by sputtering to form the frame body 6 (see FIG. 2F). The metal film is preferably Pd or a Pd alloy, but a material that does not react with the Pd layer or the Pd alloy layer to form a brittle intermetallic compound, for example, Cu or a Cu alloy can be used.

  This facilitates handling when the integral structure film 4 is peeled from the substrate 1 and when the separated integral structure film 4 is overlaid. The thickness of the frame body 6 is preferably 5 to 50 μm. The frame 6 is preferably formed to have a width of 2 to 20 mm from the outer peripheral edge of the Pd layer or the Pd alloy layer 3.

  The frame forming step (S5) may be performed before the sputtering step (S2) (see FIGS. 3 and 4).

  Next, after removing the metal mask 5 (see FIG. 2G), in the peeling step (S6), the integrated structure film 4 including the Pd layer or the Pd alloy layers 2 and 3, the metal mask 5 and the frame 6 is formed as a substrate. It peels from 1 (refer FIG. 2 (h) (i)). In order to peel the monolithic structure film 4 from the substrate 1, for example, it may be mechanically peeled off using tweezers P, or may be peeled off using hydrogen gas. For example, it may be peeled off by dipping in an inorganic acid such as nitric acid. Such means is appropriately selected depending on the film thickness and composition of the Pd layer or the Pd alloy layer.

  Next, in the heat treatment step (S7), the integrated structure film 4 obtained in the peeling step (S6) is heat-treated in a vacuum or in an inert atmosphere. This is because the sputtered film made of Pd or Pd alloy as it is peeled off from the substrate is hard, brittle and easily damaged.

  The heat treatment in a vacuum or in an inert atmosphere is performed by placing the integral structure film 4 on a flat plate 7 (see FIGS. 2J and 2K). As the flat plate 7, a ceramic sintered plate such as alumina or zirconia or a metal plate coated with ceramics such as alumina or TiN can be used. Since the metal plate reacts with Pd when used alone, it is not preferable to use the metal plate alone. In short, any material that does not chemically react with Pd may be used.

  The heat treatment temperature in vacuum or in an inert atmosphere is 400 to 1200 ° C. At a temperature lower than 400 ° C., the completed hydrogen permeable membrane 8 (see FIG. 2 (l)) is hard, brittle and easily damaged. On the other hand, at a temperature exceeding 1200 ° C., the hydrogen permeable membrane 8 may be deformed.

  In the present invention, a very thin hydrogen permeable film 8 of 5 μm or less can be obtained by sputtering, and the hydrogen permeability can be improved. In addition, although it is such a thin film, the foreign matter adhering to the substrate 1 and the first Pd layer or the Pd alloy layer 2 can be efficiently removed by washing in a conductive film state. The formation of pinholes in the Pd layer 2 or the Pd alloy layer 3 is suppressed. In the subsequent step of laminating the second Pd layer or Pd alloy layer 3, the pin hole 2 a formed in the first Pd layer or Pd alloy layer 2 is sealed with the second Pd layer or Pd alloy layer 3. By forming the holes, it is possible to prevent the generation of pinholes throughout the thickness direction of the hydrogen permeable membrane 8.

  Although the present invention has been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the essence.

(Example 1)
The process of Example 1 is demonstrated using FIG. 1 and FIG.

  Substrate cleaning step (S1): A crown glass substrate 1 (manufactured by Matsunami Glass Industrial Co., Ltd.) having a size of 50 mm × 50 mm was prepared (see FIG. 2A) and ultrasonically cleaned in ethanol for 20 minutes.

Sputtering process (S2): The board | substrate 1 was attached to sputtering apparatus (the product made by ULVAC, SBH2306RDE) with the Pd target. Thereafter, the inside of the sputtering apparatus was evacuated to 5 × 10 ⁻⁴ Pa or less, and then the substrate was sputter-etched with RF 200 W for cleaning the substrate at an Ar gas pressure of 1 Pa. Subsequently, a current of DC 1.0 A was passed through the Pd target to form a Pd layer 2 having a thickness of 0.5 μm on the substrate (see FIG. 2B).

  Film cleaning step (S3): The Pd layer 2 remaining attached to the substrate 1 was ultrasonically cleaned in ethanol for 20 minutes. The pinhole 2a was formed by this washing | cleaning (refer FIG.2 (c)).

Sputtering lamination step (S4): The substrate 1 on which the ultrasonically cleaned Pd layer 2 is formed is attached to the sputtering apparatus again, evacuated to 5 × 10 ⁻⁴ Pa or less, and then subjected to the Pd target at an Ar gas pressure of 1 Pa. A current of 1.0 A DC was supplied to form a 1.5 μm thick Pd layer 3 on the Pd layer 2 whose film was cleaned in the step (S3) (see FIG. 2D).

Frame forming step (S5): A SUS430 metal mask 5 having a size of 30 mm × 30 mm is attached on the Pd layer 3 (see FIG. 2E), and the inside of the sputtering apparatus is again 5 × 10 ⁻⁴ Pa. After evacuating below, a current of DC 1.0 A was passed through the Pd target, and a Pd layer having a thickness of 8 μm was laminated on the outer periphery of the upper surface of the Pd layer 3 to form a frame 6 (FIG. 2 (f )reference).

  Peeling step (S6): After removing the metal mask 5 (see FIG. 2G), the integral structure film 4 composed of the Pd layers 2, 3, 6 is picked with the tweezers P and peeled off from the substrate 1 (FIG. 2). (See (h) and (i)). The peeled monolithic structure film 4 is formed by forming a frame 6 having an outer diameter of 50 mm × 50 mm and a thickness of 10 μm outside 30 mm × 30 mm. It is a 0 μm Pd film.

Heat treatment step (S7): The peeled monolithic structure film 4 is placed on an alumina plate 7 (see FIGS. 2 (j) and (k)), placed in a vacuum heating furnace, evacuated to 5 × 10 ⁻³ Pa, and then 500 Heat treatment was carried out at 2 ° C. for 2 hours to obtain a hydrogen permeable membrane 8 (see FIG. 2 (l)).

  When the obtained hydrogen permeable film 8 was observed with an optical microscope, transmitted light due to the opened pinhole was not observed.

  Next, the obtained hydrogen permeable membrane 8 was cut to a size of φ10 mm, overlapped with a porous support, and attached to a hydrogen permeation measuring device having a permeable surface φ8 mm produced by the present inventors. After the inside of the hydrogen permeation measuring apparatus was evacuated and then introduced with nitrogen gas, the hydrogen permeable membrane 8 was pressurized to 0.8 MPa. As a result, no leakage of nitrogen gas from the pinhole was observed.

Next, the electric furnace of the hydrogen permeation measuring device was heated, heated to 500 ° C., replaced with nitrogen gas from hydrogen gas, and a pressure of 0.2 MPa was applied to the hydrogen permeable membrane. A hydrogen permeation flow rate of 114 cm ³ / min was measured at 1 atm and 0 ° C. by FM-390 manufactured by Aera Co., Ltd. The measured hydrogen permeation flow rate coincided with the hydrogen permeation flow rate of the Pd film having a film thickness of 2 μm calculated from the known hydrogen permeation coefficient of Pd. The measurement results are shown in Table 1.

  As described above, in this example, the generation of pinholes was suppressed, and a hydrogen permeable membrane having a thin film thickness and good hydrogen permeability was obtained.

(Example 2)
The steps of Example 2 will be described with reference to FIGS.

  Substrate cleaning step (S1): A crown glass substrate 1 (manufactured by Matsunami Glass Industrial Co., Ltd.) having a size of 50 mm × 50 mm was prepared (see FIG. 4A) and ultrasonically cleaned in ethanol for 20 minutes.

Frame body forming step (S5): A SUS430 metal mask 5 having a size of 30 mm × 30 mm is mounted on the crown glass substrate 1 (see FIG. 4B), and together with a Pd-23 mol% Ag alloy target, a sputtering apparatus ( It was attached to ULVAC, SBH2306RDE. Thereafter, the inside of the sputtering apparatus was evacuated to 5 × 10 ⁻⁴ Pa or less, and then the substrate 1 was sputter-etched with RF 200 W for cleaning the substrate at an Ar gas pressure of 1 Pa. Subsequently, a current of DC 1.0 A was applied only to the Pd—Ag alloy target, and a frame 6 made of a Pd—Ag alloy layer having a film thickness of 9 μm was formed in a portion other than the mask on the substrate (FIG. 4C). reference).

Sputtering step (S2): The metal mask 5 is removed from the substrate 1 (see FIG. 4D), the sputtering apparatus is evacuated again to 5 × 10 ⁻⁴ Pa or less, and then the Pd—Ag alloy at an Ar gas pressure of 1 Pa. A current of DC 1.0 A was passed through only the target to form a Pd—Ag alloy layer 2 having a thickness of 0.1 μm (see FIG. 4E).

  Membrane cleaning step (S3): The surface of the Pd—Ag alloy layer 2 was brushed with a dry nonwoven fabric and then sprayed with alternative chlorofluorocarbon. The pinhole 2a was formed by this cleaning (see FIG. 4F).

Sputtering lamination step (S4): After the inside of the sputtering apparatus was evacuated again to 5 × 10 ⁻⁴ Pa or less, a DC 1.0A current was passed through the Pd—Ag alloy target at an Ar gas pressure of 1 Pa, and the film thickness was formed on the substrate. A Pd—Ag alloy layer 3 having a thickness of 0.9 μm was formed (see FIG. 4G).

  Peeling step (S6): The substrate 1 with the Pd—Ag alloy layers 2 and 3 is taken out from the sputtering apparatus, put into a vacuum glove box, evacuated, and a mixed gas of 95% nitrogen-5% hydrogen is introduced, Similarly to the Pd—Ag alloy layers 2 and 3, the integral structure film 4 including the Pd—Ag alloy frame 6 was peeled from the substrate 1 (see FIGS. 4H and 4I). The peeled monolithic structure film 4 is formed by forming a frame 6 having an outer diameter of 50 mm × 50 mm and a thickness of 10 μm outside 30 mm × 30 mm, and the inner side of the frame 6 is Pd− having a total film thickness of 1 μm. It was a 23 mol% Ag film.

Heat treatment step (S7): Placed on alumina plate 7 (see FIGS. 4 (j) and (k)), put in a vacuum heating furnace, evacuated to 5 × 10 ⁻³ Pa, and then heat treated at 1000 ° C. for 2 hours. As a result, a hydrogen permeable membrane 8 was obtained (see FIG. 4L).

  When the obtained hydrogen permeable film 8 was observed with an optical microscope, transmitted light due to the opened pinhole was not observed.

Next, when nitrogen gas was pressurized with a hydrogen permeation measuring device in the same manner as in Example 1, no leakage of nitrogen gas was observed. Subsequently, when the hydrogen permeation flow rate was measured in the same manner as in Example 1, it was 265 cm ³ / min in terms of 1 atm and 0 ° C. The measured hydrogen permeation flow rate coincided with the hydrogen permeation flow rate of the Pd-23 mol% Ag alloy film having a film thickness of 1 μm calculated from the known hydrogen permeation coefficient of the Pd-23 mol% Ag alloy. The measurement results are shown in Table 1.

  As described above, in this example, the generation of pinholes was suppressed, and a hydrogen permeable membrane having a thin film thickness and good hydrogen permeability was obtained.

(Comparative Example 1)
A Pd film was produced in the same manner as in Example 1 except that the film cleaning step (S3) was not performed. As a result of observation with an optical microscope, the hydrogen permeable film 8 was observed to transmit light through an open pinhole. The pinhole density was 0.44 / cm ² . Further, when nitrogen gas was pressurized with a hydrogen permeation measuring device in the same manner as in Example 1, leakage of nitrogen gas occurred. Hydrogen permeation flow rate measurement was not performed because hydrogen leaked from the pinhole. The results are shown in Table 1.

(Comparative Example 2)
A hydrogen permeable film 8 was produced in the same manner as in Example 1 except that the film thickness in the sputtering step (S2) was 1.95 μm and the film thickness in the sputtering lamination step (S4) was 0.05 μm. As a result of observation with an optical microscope, the hydrogen permeable film 8 reopened due to breakage of the sealed pinhole 2a, and transmitted light by the pinhole was recognized. The pinhole density was 0.21 / cm ² . Further, when nitrogen gas was pressurized with a hydrogen permeation measuring device in the same manner as in Example 1, leakage of nitrogen gas occurred. Hydrogen permeation flow rate measurement was not performed because hydrogen leaked from the pinhole. The results are shown in Table 1 (Comparative Example 3).
A Pd film was produced in the same manner as in Example 1 except that the temperature in the heat treatment step (S7) was 300 ° C. As a result of observation with an optical microscope, the hydrogen permeable film 8 was not observed to transmit light due to the opened pinhole. However, when nitrogen gas was pressurized with a hydrogen permeation measuring device in the same manner as in Example 1, the hydrogen permeable membrane 8 was broken and nitrogen gas leaked. Since it could not be used as a hydrogen permeable membrane, the hydrogen permeation flow rate could not be measured. The results are shown in Table 1.

Example 3
A hydrogen permeable film 8 was produced in the same manner as in Example 1 except that the sputter etching in the substrate cleaning step (S1) and the sputtering step (S2) was not performed. As a result of observation with an optical microscope, the hydrogen permeable film 8 was not observed to transmit light due to the opened pinhole. Further, even when nitrogen gas was pressurized with a hydrogen permeation measuring apparatus in the same manner as in Example 1, no leakage of nitrogen gas was observed. Subsequently, as a result of replacing with hydrogen gas and measuring the permeation flow rate in the same manner as in Example 1, a hydrogen permeation flow rate of 116 cm ³ / min in terms of 1 atm and 0 ° C. was measured. The measured hydrogen permeation flow rate coincided with the hydrogen permeation flow rate of the Pd film having a film thickness of 2 μm calculated from the known hydrogen permeation coefficient of Pd. The measurement results are shown in Table 1.

  As described above, in Example 3, the generation of pinholes in the hydrogen permeable film was suppressed without performing substrate cleaning, and a hydrogen permeable film having a thin film thickness and good hydrogen permeability was obtained.

(Comparative Example 4)
A hydrogen permeable membrane 8 was obtained in the same manner as in Example 1 except that the film thickness in the sputtering step (S2) was 2 μm and the film cleaning step (S3) and the sputtering lamination step (S4) were not performed. As a result of observation with an optical microscope, the hydrogen permeable film 8 was observed to transmit light through an open pinhole. The pinhole density was 0.32 holes / cm ² . Further, when nitrogen gas was pressurized with a hydrogen permeation measuring device in the same manner as in Example 1, leakage of nitrogen gas occurred. Hydrogen permeation flow rate measurement was not performed because hydrogen leaked from the pinhole. The results are shown in Table 1.

FIG. 1 is an explanatory view showing the flow of the first embodiment and Example 1 of the method for producing a hydrogen permeable membrane of the present invention. FIG. 2 is a process diagram of the first embodiment and Example 1 of the method for producing a hydrogen permeable membrane of the present invention. FIG. 3 is an explanatory diagram showing the flow of Example 2 of the method for producing a hydrogen permeable membrane of the present invention. FIG. 4 is a process diagram of Example 2 of the method for producing a hydrogen permeable membrane of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 1st Pd layer or Pd alloy layer 2a Pinhole 3 2nd Pd layer or Pd alloy layer 4 Monolithic film 5 Metal mask 6 Frame 7 Flat plate (alumina plate)
8 Hydrogen permeable membrane P Tweezers S1 Substrate cleaning step S2 Sputtering step S3 Film cleaning step S4 Sputtering lamination step S5 Frame forming step S6 Peeling step S7 Heat treatment step

Claims (8)

Forming a first Pd layer or a Pd alloy layer on the substrate by sputtering;
Cleaning the first Pd layer or Pd alloy layer;
Laminating a second Pd layer or a Pd alloy layer by sputtering on the cleaned first Pd layer or Pd alloy layer;
Peeling off the monolithic structure film having the first Pd layer or Pd alloy layer and the second Pd layer or Pd alloy layer from the substrate;
Heat-treating the monolithic structure film at a temperature of 400 to 1200 ° C. in vacuum or in an inert atmosphere;
A method for producing a hydrogen permeable membrane having   The method for producing a hydrogen permeable membrane according to claim 1, wherein the cleaning step includes at least one of gas spraying, brushing, and ultrasonic cleaning.   The method for producing a hydrogen permeable membrane according to claim 1, further comprising a step of cleaning the substrate before the step of forming the first Pd layer or the Pd alloy layer.   2. The method for producing a hydrogen permeable membrane according to claim 1, wherein the Pd alloy layer includes at least one selected from the group consisting of a Pd—Ag alloy, a Pd—Cu alloy, a Pd—Y alloy, and a Pd—rare earth metal alloy. .   The method for manufacturing a hydrogen permeable membrane according to claim 1, wherein a frame is formed on an outer peripheral portion of the upper surface of the second Pd layer or Pd alloy layer.   The method for producing a hydrogen permeable membrane according to claim 1, wherein the maximum thickness of the integral structure membrane is 0.15 to 5 μm.   The method for producing a hydrogen permeable membrane according to claim 1, wherein the thickness of the second Pd layer or the Pd alloy layer is 0.1 μm or more.   A pinhole formed in the first Pd layer or Pd alloy layer obtained by the method for producing a hydrogen permeable membrane according to claim 1, wherein the stacked second Pd layer or Pd alloy A hydrogen permeable membrane characterized by being sealed with a layer.

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