JP2006272420A - Metal foil diffusion bonding method - Google Patents

Abstract

Disclosed is a method for diffusion bonding of a metal foil body that is capable of stable diffusion bonding and has high adhesion even if the object to be bonded has fine irregularities.
A metal plate (Ta plate) 53 to be joined 52 and metal foil bodies (Pd foil) 51a and 51b to be joined 50a and 50b are provided between a pair of pressing flat jigs 33a and 33b. Between the metal foil bodies 51a and 51b and the pressing plate jigs 33a and 33b to generate gas due to heat. And a pair of pressurizing flat jigs after interposing the peelable sheets 54a and 54b which are elastically deformed by pressurization and have good peelability between the metal foil bodies 51a and 51b and the pressurizing flat jigs 33a and 33b. 33a and 33b are diffusion bonded by heating the bonding interface of the metal plate 53 and the bonding interface of the metal foil bodies 51a and 51b while applying a predetermined pressure.
[Selection] Figure 2

Description

  The present invention relates to a diffusion bonding method of a metal foil body. For example, after mixing a hydrocarbon such as methane gas with water vapor and reforming at a high temperature, only hydrogen gas is generated from the generated mixed gas. The present invention relates to a diffusion bonding method of a metal foil body used as a method for producing a hydrogen permeable separation membrane that produces a high purity hydrogen gas by permeation separation.

  Conventionally, this type of hydrogen permeation separation membrane is known as a single layer using Pd (palladium) or an alloy containing Pd that selectively permeates only hydrogen.

  In some cases, a Pd alloy film is formed on the surface of the ceramic porous support by a plating method (see Patent Document 1).

  Further, as a hydrogen permeation separation membrane having a sandwich structure, there is also one in which a Pd film or a Pd alloy film is disposed on both surfaces of a metal film having high hydrogen permeation performance (see Patent Document 2).

  Furthermore, as a diffusion bonding method for uniformly creating a clad material having a sandwich structure, the clad material is placed in a stainless steel sheet bag, and the bag is evacuated to apply atmospheric pressure. A method of heating has been introduced (see Patent Document 3).

  First, a hydrogen separation method in which Pd or Pd alloy is used as a hydrogen permeable separation membrane will be briefly described.

  Usually, a hydrogen permeation separation membrane is used by rolling Pd or a Pd alloy into a thin film. For example, a cylindrical tube is made of a Pd film or a Pd alloy film, and one end of the tube is sealed and welded, and a pressurized raw material hydrogen gas is supplied to the outside of the tube. Hydrogen molecules dissociate in an atomic form, form a solid solution with Pd, and are taken into the Pd film.

  The taken-in hydrogen atoms diffuse from the outside of the high pressure tube to the low inside due to the hydrogen partial pressure difference inside and outside the tube, and become hydrogen molecules again on the inner surface. Impurities other than hydrogen contained in the reformed gas produced by steam reforming from methane or methanol do not react with Pd and remain outside the tube, thereby purifying the hydrogen.

  In the hydrogen permeable separation membrane of only Pd, deterioration due to hydrogen embrittlement is a problem, and it is used after being alloyed. Already, Pd alloys with 23% silver and 40% copper are well known, and hydrogen purifiers using only a single tube of Pd alloy film have been put into practical use. The thickness is as thick as 80 μm or more in order to maintain the strength, and there is a problem that the hydrogen permeation amount is small and expensive.

  FIG. 6 shows an example of a conventional hydrogen permeation separation membrane described in Patent Document 1. As shown in FIG. 6, the hydrogen separator 1 has a porous substrate 2 made of a cylindrical ceramic and a surface 2a of the porous substrate that becomes a surface to be treated outside thereof, and has hydrogen separation ability such as Pd and Pd. And a hydrogen separation membrane 4 formed by electroless plating, and the diameter of the small holes 5 of the porous substrate 2 is not more than the thickness of the hydrogen separation membrane 4 and not less than 1 μm.

  Here, the operation | movement is demonstrated about the cylindrical hydrogen separator 1 in which the hydrogen separation membrane 4 forms an outer surface part. First, when pressurized hydrogen gas is supplied to the outside of the cylindrical hydrogen separator 1 and heated to a certain temperature, the hydrogen molecules in contact with the hydrogen separation membrane 4 on the surface of the porous body 2 become atoms. Dissociate to form a solid solution with Pd and are taken into the Pd membrane, that is, into the hydrogen separation membrane 4.

  The taken-in hydrogen atoms diffuse from the outside of the high-pressure hydrogen separation membrane 4 to the low inside due to the difference in hydrogen partial pressure inside and outside the hydrogen separation membrane 4, and become hydrogen molecules again on the inside surface. After that, it flows in the small holes 5 of the cylindrical porous substrate 2 from the surface 2a of the porous body. Since many impurities contained in the reformed hydrogen gas do not react with Pd, they remain outside the hydrogen separator 1, thereby purifying the hydrogen.

  However, in the conventional method of forming a Pd film or a Pd alloy film on the outer surface of a porous substrate made of ceramic by a plating method, the mechanical strength as a structure can be increased, and it is a thin film of about 1 to 5 μm. A certain amount of hydrogen separation ability can be secured, but even if the pore diameter of the porous support is selected so as not to affect the amount of permeation, the plating thickness varies in the plating process, and the Pd alloy film is thin. Pinholes remain in the part, and it is difficult to eliminate the leakage.

  Therefore, when the purity of the reformed hydrogen gas generated as a result of steam reforming is low, the purity of the hydrogen gas obtained by permeating through the membrane is also proportionally deteriorated. For example, when the thickness of the Pd alloy film is 5 μm, the purity At about 99.9%, 50 ppm or more of carbon monoxide was mixed in, so that the permeated gas could not be supplied to a solid polymer membrane fuel cell. In addition, when used for a long time, the strength is lowered due to hydrogen embrittlement, and in particular, there is a problem that deterioration of the pinhole portion is accelerated and breakage is likely to occur.

  FIG. 7 shows a conventional hydrogen permeable membrane described in Patent Document 2. As shown in FIG. 7, the hydrogen permeable film 6 is composed of a metal film 7 having high hydrogen permeable performance and a Pd film or a Pd alloy film 8 disposed on both sides thereof.

  The hydrogen permeable membrane 6 having the sandwich structure is produced in the following forms (1) and (2).

  (1) The metal film 7 having high hydrogen permeation performance and the Pd film or the Pd alloy film 8 are dry-etched in vacuum to remove impurities and oxide layers on the surface. Etching can be performed by ion bombardment with inert gas ions. Thereafter, a Pd film or a Pd film is disposed on both surfaces of a metal film having a high hydrogen permeation performance while maintaining a vacuum, and is rolled in a vacuum.

  (2) The Pd film or the Pd alloy film 8 is disposed on both surfaces of the metal film 7 having high hydrogen permeation performance, and is heated in vacuum to remove impurities and oxide layers. A technique such as hot pressing can be applied to heating in vacuum. Then roll.

  An attachment method and operation of the hydrogen permeable membrane having the sandwich structure thus prepared will be described.

  As shown in FIG. 8, a cylindrical tube is usually formed by winding a hydrogen permeable membrane 6 around an outer layer 10 of a cylindrical porous body 9 and welding a mating portion 11 with a copper braze 12. Next, one end of the tube is hermetically welded, and pressurized raw material hydrogen gas is supplied to the outside of the tube.

  When heated to a certain temperature, hydrogen molecules in contact with the tube surface dissociate into atoms, form a solid solution with Pd, and are taken into the Pd film.

  Due to the difference in hydrogen partial pressure inside and outside the tube, the taken-in hydrogen atoms quickly diffuse from the outside of the tube with high hydrogen partial pressure through the metal film with high hydrogen permeability to the inside with low hydrogen partial pressure, and the Pd film inside It becomes hydrogen molecule again on the surface.

  Many impurities contained in the reformed hydrogen gas do not react with Pd, and therefore remain outside the tube, thereby purifying the hydrogen.

  Since the hydrogen permeable membrane 6 having the sandwich structure made in this way uses a metal 7 having a high hydrogen diffusion coefficient and a high hydrogen permeation performance as the core material, it is more than that using a single Pd alloy tube. High hydrogen permeation performance can be obtained.

  In addition, the Pd film or alloy film is arranged on both sides of the metal film with high hydrogen permeation performance, so that no oxide film layer is formed on the surface, and since it has a laminated structure, it has a dense hydrogen permeation without pinholes. A film is obtained, and furthermore, a Pd film or a Pd alloy film is uniformly disposed on both sides of a metal film having high hydrogen permeability, which is considered to be weak against hydrogen embrittlement. Therefore, deterioration in physical properties due to hydrogen embrittlement is reduced.

  FIG. 9 shows a conventional diffusion bonding method described in Patent Document 3. In FIG. 9, in a combination of a tantalum plate 21, a copper plate 22, and a stainless steel (SUS316L) plate 23, a silver brazing thin layer 24 (foil or powder) such as silver or Ag-Cu is provided between the tantalum plate 21 and the copper plate 22. Are inserted into a bag 26 made of a metal foil such as stainless steel or a thin metal plate, the inside of the bag is evacuated from a pipe portion 27, and sealed with a seam weld 28. There is a method for producing a clad by heating to 800 to 1050 ° C. while applying atmospheric pressure.

With this method of pressure application, a uniform pressure of atmospheric pressure is applied from the outside of the bag, so there is no need for a large diffusion bonding device combined with a hydraulic press, and diffusion bonding is possible stably. Yes, a clad material with uniform strength can be obtained.
JP 2000-317282 A JP-A-11-276866 JP-A-5-169281

  The conventional method of placing the Pd film or the Pd alloy film 8 on both surfaces of the metal film 7 having high hydrogen permeation performance and heating and pressing or rolling in vacuum is a process of removing impurities and oxide layers. It shares the diffusion bonding process that forms the sandwich structure, and requires a high pressure to make the metal film 7 adhere uniformly, making the device large, very complex and expensive, and used for hydrogen permeable membranes. In the case of a thin metal foil of about 10 μm, such as Pd or Pd alloy, the unevenness of the metal surface with high hydrogen permeation performance to be bonded is not uniformly applied, and the entire surface has a uniform adhesion strength. Bonding is difficult.

  Also, as shown in Patent Document 3, a release material is placed on both outer sides of the clad laminate material, put into a metal foil or thin metal plate bag such as stainless steel, the bag is sealed in vacuum, and atmospheric pressure is applied. Even if it is a diffusion bonding method in which heating is performed as it is, if a hard release material such as 18Cr-3Al steel with a temper collar is used, it will not stick to a jig or a clad material. In the case of a thin metal foil of about 10 μm, such as Pd or Pd alloy used for the metal, the surface of the metal surface with high hydrogen permeability that becomes the bonded surface is not evenly applied to the uneven details, and the entire surface is uniformly adhered. Bonding with strength is difficult.

  In view of the above-described conventional problems, an object of the present invention is to provide a diffusion bonding method for a metal foil body that is capable of stable diffusion bonding and has strong adhesion even if the objects to be bonded have fine irregularities.

  In order to achieve the above object, the metal foil body diffusion bonding method of the present invention includes a metal plate to be bonded and a metal foil body to be bonded to each other between a pair of pressing flat jigs. Between the back surface of the metal foil body opposite to the bonding interface of the metal foil body and the pressurizing flat plate jig, there is no generation of gas due to heat, and it is elastic by pressurization. After being deformed and interposing a peelable sheet having good releasability between the metal foil body and the flat plate jig for pressurization, a pair of the flat plate jigs for pressurization are used to connect the joining interface of the metal plate and the metal foil body. Thus, diffusion bonding is performed by heating the bonding interface with a predetermined pressure.

  According to the present invention, by using a peelable sheet that is elastically deformed by pressurization, the metal thin body follows the uniform unevenness of the joined body, and the pressure is applied uniformly, so a very stable diffusion Bonding is possible and adhesion can be improved.

  In the present invention, when using a felt of highly purified carbon fiber having reducibility as the above-described peelable sheet, in addition to preventing oxidation by vacuuming, by creating a reducing atmosphere of graphite at high temperature It has the function of positively removing the oxide film at the bonding interface.

  This greatly simplifies the apparatus, and even in the case of a thin metal foil of about 10 μm such as palladium Pd or Pd alloy used for the hydrogen permeable membrane, the unevenness of the metal surface with high hydrogen permeability that becomes the bonded surface A uniform force is applied to the details, and bonding with uniform adhesion strength over the entire surface becomes possible. Further, when used as a hydrogen permeable separation membrane, not only the peel strength as a laminated membrane is increased, but also the hydrogen permeation performance can be improved.

  In the diffusion bonding method of the metal foil body of the present invention, in the case where the bonded body is a diffusion bonding of a relatively thin metal foil body, a release sheet that elastically deforms from the back surface is interposed, so that the fine unevenness of the bonded body is obtained. On the other hand, since the metal thin body follows the pressure uniformly, extremely stable diffusion bonding is possible, and the adhesion is improved, providing a strong diffusion bonded body that does not peel off in the subsequent rolling process. I can do it.

  In addition, if the carbon fiber felt subjected to high purity treatment is used as a peelable sheet, not only the oxidation of the joint surface by evacuation in the diffusion bonding process, but also graphite creates a reducing atmosphere at high temperature, It functions to remove the oxide film at the bonding interface, eliminates the etching process at the bonding interface, and greatly simplifies the apparatus, and is as thin as 10 μm like Pd and Pd alloys used for hydrogen permeable membranes. Even in the case of a metal foil, a force is evenly applied to uneven portions of a metal surface having high hydrogen permeation performance as a bonded surface, and bonding with uniform adhesion strength on the entire surface becomes possible. Therefore, when used as a hydrogen permeation separation membrane, not only the peel strength as a laminated membrane is increased, but also the hydrogen permeation performance can be improved.

  The invention of the metal foil body diffusion bonding method according to claim 1 is characterized in that a metal plate to be joined and a metal foil body to be joined are bonded to each other between a pair of pressing flat jigs. Are arranged so as to face each other, and there is no generation of gas due to heat between the back surface opposite to the bonding interface of the metal foil body and the pressing plate jig, and elastically deforms by pressing, After interposing a releasable sheet having good releasability between the metal foil body and the pressing flat plate jig, a pair of the flat plate jigs for pressing causes the bonding interface of the metal plate and the bonding interface of the metal foil body. Is heated by pressurizing at a predetermined pressure to perform diffusion bonding, and gas generated by heat between the back surface opposite to the bonding interface of the metal foil body to be a bonded body and the pressing plate jig. Is not deformed and elastically deformed by pressurization, and the peelability between the metal foil and the flat plate jig for pressurization is good. By interposing the release sheet, since the uniformly pressure to follow the metal thin body against fine unevenness of the object to be bonded join enables very stable diffusion bonding, adhesion is improved.

  The invention of the metal foil body diffusion bonding method according to claim 2 is a method in which the thickness of the metal foil body according to the invention of claim 1 is set to 1 μm or more and 100 μm or less, and diffusion bonding is performed for a thin film of 1 μm or less. The handling of the work is also difficult, and if it is 100 μm or more, the metal thin body follows the fine irregularities of the joined objects even if a peelable sheet that has rigidity as a metal plate and elastically deforms on the back is interposed. do not do. Therefore, very stable diffusion bonding is possible with a metal foil of 1 μm or more and 100 μm or less, and the adhesion is improved.

  Invention of the metal foil body diffusion bonding method according to claim 3 uses a silica fiber non-woven fabric subjected to high purity treatment as the peelable sheet in the invention according to claim 1 or 2, and 1000 Silica fiber nonwoven fabric that has been highly purified by firing at a temperature of ℃ or higher does not generate gas during diffusion bonding at high temperatures in the vacuum, and can follow even fine irregularities by pressure, providing moderate elasticity. In addition, very stable diffusion bonding is possible, and the adhesion is improved.

  The invention of the metal foil body diffusion bonding method according to claim 4 uses a highly purified graphite as the releasable sheet in the invention according to claim 1 or 2, and the high purity treatment. By using the obtained graphite as a peelable sheet, the reducing action as carbon works, it becomes possible to remove the oxide film at the bonding interface, and the etching process at the bonding interface can be simplified.

  The invention of the diffusion bonding method of the metal foil according to claim 5 uses a felt of carbon fiber subjected to high purity treatment as the peelable sheet in the invention according to claim 1 or 2, 2000 The carbon fiber felt, which has been highly purified by firing at around ℃, does not generate gas during diffusion bonding at high temperatures in the vacuum, and can follow fine irregularities with pressure, leaving moderate elasticity. Very stable diffusion bonding is possible, and the adhesion of the bonding surface is improved.

  Furthermore, graphite has the function of removing the oxide film at the bonding interface by creating a reducing atmosphere at high temperature and under vacuum, and is a thin metal foil of about 10 μm, such as Pd and Pd alloys used for hydrogen permeable films. In the case of a body, a force is evenly applied to uneven portions of a metal surface having a high hydrogen permeation performance as a bonded surface, and bonding with uniform adhesion strength over the entire surface becomes possible.

  The invention of the diffusion bonding method of a metal foil body according to claim 6 is the invention according to any one of claims 1 to 5, wherein a metal plate having a high hydrogen permeability coefficient is used for the object to be bonded, At the double-sided bonding interface of the metal plate to be bonded, a foil of palladium or palladium alloy is used as the metal foil body of the bonded body, and the laminated type hydrogen whose oxide film on the bonded interface greatly affects the hydrogen permeation performance. By utilizing it as a permeation separation membrane, even in the case of a thin metal foil of about 10 μm such as Pd or Pd alloy used for a hydrogen permeation membrane, it is possible to reduce the unevenness of the metal surface with high hydrogen permeation performance to be a bonded surface. In addition, a force is applied evenly, and bonding with uniform adhesion strength is possible without applying a high pressure, the subsequent rolling process can be smoothed, and the hydrogen permeation performance is improved.

  The metal foil body diffusion bonding method according to a seventh aspect of the invention is characterized in that the metal plate having high hydrogen permeability in the invention of the sixth aspect is made of Ta, Nb, V, Ta alloy, Nb alloy, or V alloy. The metal foil body diffusion bonding method of the present invention, which can increase the adhesion and remove the oxide film, is very effective for these metals that are easy to make an oxide film. work.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a schematic cross-sectional configuration diagram showing a diffusion bonding apparatus 30 used in a metal foil body diffusion bonding method according to Embodiment 1 of the present invention. FIG. 2 is an enlarged cross-sectional view showing the press member 31 of the diffusion bonding apparatus 30 according to the first embodiment. FIG. 3 is a perspective view of the laminated hydrogen permeable separation membrane 32 obtained by the metal foil diffusion bonding method of the first embodiment. FIG. 4 is an enlarged cross-sectional view showing the press member 31 before being pressed by the metal foil body diffusion bonding method of the first embodiment. FIG. 5 is an enlarged cross-sectional view showing the press member 31 after being pressed by the metal foil body diffusion bonding method of the first embodiment.

  In FIG. 1, the diffusion bonding apparatus 30 includes a vacuum chamber 34, a high temperature diffusion furnace 35, and a hydraulic press 36.

  The vacuum chamber 34 includes a stainless steel upper chamber 37, a lower chamber 38, a vacuum pump 39 using an oil rotary pump and an oil diffusion pump as a vacuum exhaust system, and the upper chamber 37 is removed by detaching the pin 41 of the connecting portion 40. The lower chamber 38 can be opened and closed up and down.

  The high-temperature diffusion furnace 35 is surrounded by a ceramic heat insulating wall 42 having a structure (not shown) that can be opened at the front surface, and a heater 43 made of Kanthal having high heat resistance is embedded therein. 44 can control the temperature in the high-temperature diffusion furnace 35.

  There is a lower stage 45 in the high-temperature diffusion furnace 35, and by installing the press member 31 on the lower stage 45, the upper stage 46 can be lowered by the hydraulic press 36 and pressure can be applied to the press member 31.

  The drive shaft 47 of the upper stage 46 passes through the heat insulating wall 42 and the upper chamber 37 and is connected to the hydraulic press 36. An intersection 48 between the drive shaft 47 and the upper chamber 37 can be driven by applying a bellows or the like. The inside of the vacuum chamber 34 and the outside are completely sealed by an airtight mechanism.

  In FIG. 2, the press member 46 includes a pair of pressing plate jigs 33 a and 33 b obtained by cutting a SUS316L stainless steel plate to a certain size, and a pair of pressing plate jigs 33 a and 33 b that are fixed. Bolt 49.

  Between the pressing plate jigs 33a and 33b, the two joined bodies 50a and 50b are sandwiched between the metal foil bodies 51a and 51b of palladium Pd or palladium alloy and the two metal foil bodies 51a and 51b. The tantalum metal plates 53 having a high hydrogen permeation coefficient, which are to be joined 52, are stacked and set so that the joining interfaces between the metal foil bodies 51a and 51b and the metal plate 53 face each other.

  Furthermore, the joined bodies 50a and 50b are made of relatively thin metal foil bodies 51a and 51b. The back surface opposite to the joining interface of the metal foil bodies 51a and 51b and the pressing plate jigs 33a and 33b There is no generation of gas due to heat, elastic deformation is caused by pressurization, and the releasability after the diffusion bonding process between the metal foil bodies 51a and 51b of the joined bodies 50a and 50b and the pressing plate jigs 33a and 33b. Is formed in a state in which releasable sheets 54a and 54b are interposed.

  As the material of the peelable sheets 54a and 54b, silica fiber non-woven fabric (Advantech Toyo Co., Ltd., silica fiber filter paper, QR-100) purified at a temperature of 1000 ° C. or higher, or graphite purified at about 2000 ° C. (Nippon Carbon Co., Ltd., Nika Film, FL-300SH) and carbon fiber felt (Nihon Carbon Co., Carboron, GF-20-2F) that has been highly purified at about 2000 ° C. can be used.

  The laminated hydrogen permeable separation membrane 32 shown in FIG. 3 is obtained by joining palladium or palladium alloy joined bodies 50a and 50b to the tantalum metal plate 53 as diffusion foils as the metal foil bodies 51a and 51b.

  Next, the hydrogen permeable separation membrane 32 in which the metal foil bodies 51a and 51b of the joined bodies 50a and 50b are attached to the metal plate 53 of the joined body 52 by diffusion bonding by the metal foil body diffusion bonding method of the present embodiment. The manufacturing method and the action during the diffusion bonding step will be described with reference to FIGS.

  The hydrogen permeable separation membrane 32 includes two Pd foils having a thickness of 10 μm cut into a predetermined size as metal foil bodies 51 a and 51 b of the joined bodies 50 a and 50 b, and a metal plate 53 of the joined body 52. A Ta plate having a thickness of 500 μm cut into a predetermined size was used.

  First, after degreasing the surface of the Ta plate, which becomes the metal plate 53 having a high hydrogen permeability coefficient, immersion etching treatment is performed for 20 minutes with hydrofluoric acid having a concentration of about 0.1 mol, and sufficient rinsing and azeotropic drying with alcohol are performed. The two Pd foils that have been degreased and cleaned are overlapped and set.

  Next, a high-purity carbon fiber felt as a peelable sheet 54b is placed on the lower pressing flat plate jig 33b, and the metal plate 53 and the metal foil bodies 51a and 51b are set thereon. (The metal plate 53 sandwiched between the metal foil bodies 51a and 51b) is placed, and then the same peelable sheet 54a and the upper pressing plate jig 33a are sequentially placed thereon, and lightly tightened with the bolts 49, Prepare as a press member 31.

  Next, the pin 41 of the connecting portion 40 is removed from the vacuum chamber 34 of the diffusion bonding apparatus 30, the upper chamber 37 is moved upward, and the vacuum chamber 34 is opened.

  Next, the heat insulating wall 42 of the high temperature diffusion furnace 35 is opened, the prepared press member 31 is set at a fixed position on the lower stage 45 of the hydraulic press 36 therein, the heat insulating wall 42 is closed, and the vacuum chamber 34 is opened. The vacuum chamber 34 is sealed by returning to a fixed position and fixing the connecting portion 40 with the pin 41.

Next, the vacuum pump 39 is operated, the degree of vacuum in the vacuum chamber 34 is lowered to 10 ⁻⁵ Pa or less, the heater 43 is turned on, and the controller 44 raises the temperature to 900 ° C. After confirming the rise, the hydraulic press 36 is driven to lower the upper stage 45, pressurize the press member 31 so that a pressure of about 0.1 MPa is applied, and leave it at 900 ° C. for 2 hours.

  Thereafter, the heater 43 is turned off and cooled to 50 ° C. by furnace cooling to complete the diffusion bonding process.

  As shown in FIGS. 4 and 5, when the press member 31 is pressed, the peelable sheet 54 made of a highly purified carbon fiber felt that is elastically deformed by the pressurization is deformed but is a metal foil body. Is deformed along the irregularities on the surface of the metal plate 53.

  Accordingly, the gap 55 between the metal foil body 51 and the metal plate 53 that has been generated when no pressure is applied is eliminated, and the bonding interface between the metal foil body 51 and the metal plate 53 is adhered to the entire surface. Diffusion bonding is performed smoothly.

  As in the embodiment of Patent Document 3, if the material is hard such as 18Cr-3Al steel with a temper collar formed as the release material 25, the gap 55 is retained, so only diffusion bonding at the convex portion is possible. , And the adhesion of the concave portion becomes insufficient, so that the adhesion is extremely reduced.

  In addition, by applying a felt of carbon fiber purified at about 2000 ° C. as the peelable sheet 54, the carbon is equivalent to the tantalum oxide of the oxide film formed on the tantalum surface as shown in (Equation 1). As a reducing agent, as the high temperature diffusion furnace 35 becomes high temperature, it works in the direction in which oxygen of the oxide film formed on the surface of the tantalum metal foil body 51 is removed, further increasing the adhesion and greatly affecting the hydrogen permeation amount. The decrease in the oxide film, which is supposed to give, suppresses the decrease in hydrogen permeation.

次に、５０℃にまで冷却した後、二段式圧延機で拡散接合させ作成した５２０μｍの試料を５０μｍにまでロール圧延して水素透過分離膜３２として完成させる。

Next, after cooling to 50 ° C., a 520 μm sample prepared by diffusion bonding with a two-stage rolling mill is rolled to 50 μm to complete the hydrogen permeable separation membrane 32.

  When the peelable sheet 54 was not used, the palladium metal foil formed on the tantalum surface was very easily peeled off during rolling, and a good product could not be obtained as the hydrogen permeable separation membrane 32. The sample prepared in Embodiment 1 had a good adhesion and a very good yield.

  As described above, in the metal foil body diffusion bonding method of the present embodiment, the metal plate (Ta plate) 53 to be joined 52 and the joined body 50a, between the pair of pressing flat plate jigs 33a and 33b. The metal foil bodies (Pd foils) 51a and 51b to be 50b are arranged so that their joint interfaces face each other, and the back surface opposite to the joint interface of the metal foil bodies 51a and 51b and the flat plate for pressurization There is no gas generation due to heat between the tools 33a and 33b, elastic deformation is caused by pressurization, and a peelable sheet 54a, which has good peelability between the metal foil bodies 51a and 51b and the pressurizing flat jigs 33a and 33b, After interposing 54b, diffusion bonding is performed by heating the bonding interface of the metal plate 53 and the bonding interface of the metal foil bodies 51a and 51b with a pair of pressure by a pair of pressing plate jigs 33a and 33b. To be joined 5 Since the metal thin bodies 51a, 51b with respect to fine unevenness of applied uniformly pressure to follow, it is possible to very stable diffusion bonding, adhesion is improved.

  In the first embodiment of the present invention, the tantalum metal plate 52 is employed, but any metal plate having a high hydrogen permeation coefficient can be applied, and in particular, transition metals such as tantalum (Ta), niobium (Nb), and vanadium ( V), and their alloys are effective and are not limited to tantalum metal plates.

  Further, as the material of the peelable sheet 54, in the first embodiment of the present invention, a carbon fiber felt (Nihon Carbon Co., Carbon, GF-20-2F) purified at about 2000 ° C. was used. In addition, the silica fiber nonwoven fabric (Advantech Toyo Co., Ltd., silica fiber filter paper, QR-100) that has been highly purified at 1000 ° C. or higher is good because it applies pressure to the appropriate bonding interface in terms of surface denseness, Graphite (Nihon Carbon Co., Nika Film, FL-300SH) purified at 2000 ° C has the same effect, does not generate gas due to heat, is elastically deformed by pressurization, metal foil and heating flat plate Any material can be used as long as it has good releasability from the jig, and the material is not limited to felt of carbon fiber.

  Further, when the thickness of the metal foil body 51 is 1 μm or less, it is very difficult to handle, and the metallic material of the metal foil body 51 is completely diffused and absorbed by the metal plate 53, so that the catalytic effect on the surface can be regulated. Disappear.

  Further, if the thickness of the metal foil body 51 is 100 μm or more, even if the peelable sheet 54 having rigidity as the metal foil body 51 and elastically deforming from the back surface is interposed, the fine unevenness of the bonded body 52 is formed. On the other hand, since the metal foil body 51 does not follow, the effect is reduced.

  Therefore, very stable diffusion bonding is possible with the metal foil body 51 of 1 μm or more and 100 μm or less, and the adhesion is improved.

  As described above, the metal foil body diffusion bonding method according to the present invention is effective not only in the field of fuel cells using a laminated hydrogen permeable separation membrane but also in the production method of a clad material, and thus has functionality. It can also be used effectively to streamline by attaching an expensive metal to an inexpensive steel material.

1 is a schematic cross-sectional configuration diagram showing a diffusion bonding apparatus used in a metal foil body diffusion bonding method according to Embodiment 1 of the present invention. The expanded sectional view which shows the press member of the diffusion bonding apparatus in Embodiment 1 The perspective view of the lamination-type hydrogen permeable separation membrane obtained with the diffusion bonding method of the metal foil body of Embodiment 1 The expanded sectional view which shows the press member before the pressurization by the diffusion bonding method of the metal foil body of Embodiment 1 The expanded sectional view which shows the press member after the pressurization by the diffusion bonding method of the metal foil body of Embodiment 1 Sectional view of a conventional hydrogen permeation separation membrane described in Patent Document 1 A perspective view of a conventional hydrogen permeation separation membrane described in Patent Document 2 A perspective view of a tube using a conventional hydrogen permeable separation membrane described in Patent Document 2 Sectional drawing which shows the conventional diffusion bonding method described in patent document 3

Explanation of symbols

33a, 33b Pressurizing flat plate jig 50a, 50b Bonded body 51a, 51b Metal foil body 52 Bonded body 53 Metal plate 54a, 54b Release sheet

Claims (7)

  Between a pair of pressurizing flat plate jigs, a metal plate to be joined and a metal foil body to be joined are arranged so that their joint interfaces face each other, and the joint interface of the metal foil bodies There is no generation of gas due to heat between the back side opposite to the pressing plate jig and elastic deformation due to pressing, and the metal foil body and the pressing plate jig have good peelability. After interposing the peelable sheet, diffusion bonding is performed by heating while pressing the bonding interface of the metal plate and the bonding interface of the metal foil body at a predetermined pressure with a pair of pressing flat jigs. A diffusion bonding method of a metal foil body characterized by the above.   The metal foil body diffusion bonding method according to claim 1, wherein the thickness of the metal foil body is 1 μm or more and 100 μm or less.   The metal foil body diffusion bonding method according to claim 1 or 2, wherein a high-purity treated silica fiber nonwoven fabric is used as the peelable sheet.   The metal foil body diffusion bonding method according to claim 1, wherein graphite having a high purity treatment is used as the peelable sheet.   The metal foil body diffusion bonding method according to claim 1 or 2, wherein a highly purified carbon fiber felt is used as the peelable sheet.   A metal plate having a high hydrogen permeability coefficient is used for the object to be bonded, and a palladium or palladium alloy foil is used as a metal foil body of the bonded object at the double-sided bonding interface of the metal plate that is the object to be bonded. The metal foil body diffusion bonding method according to any one of claims 1 to 5.   The metal foil body diffusion bonding method according to claim 6, wherein the metal plate having high hydrogen permeability is Ta, Nb, V, Ta alloy, Nb alloy, or V alloy.

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