JP2021022490A - Structure of hydrogen conduit and manufacturing method - Google Patents

Abstract

To improve the quality of laser welding, by preventing hydrogen embrittlement of a hydrogen conduit.SOLUTION: In a manufacture method of a hydrogen conduit passing gas containing hydrogen gas by welding two metal plates, a carbon film is formed on the metal plate surface of the hydrogen conduit, the two metal plates have a concave part and a flat part for the hydrogen conduit, the concave parts and the flat parts of the two metal plates are aligned, and then the weld zone around the concave part is laser welded along the concave part. Prior to carbon film formation, micro irregularities are formed on the metal surface by laser irradiation, and the carbon film is formed by CVD method and the like. The laser welded parts on the flat part of the metal plate exist at three points on one side of the concave, one structure of the laser welded part is a metal plate A, a carbon film on the metal plate A, a carbon film on the metal plate B laminated on the surface of another metal plate B in contact with the carbon film on the metal plate A, and a metal plate B, the other one is the metal plate A, a carbon film on the metal plate A or a carbon film on the metal plate B, and the metal plate B, and the remaining structure of the weld zone is the metal plate A and the metal plate B.SELECTED DRAWING: Figure 1

Description

The present invention relates to a structure of a conduit through which a gas containing hydrogen gas passes and a method for producing the same.

Fossil liquid fuels containing hydrocarbons such as gasoline, light oil, and heavy oil are mainly used as fuels for automobiles, ships, and airplanes. In addition, these liquid fuels and hydrocarbon fuels such as coal and natural gas are mainly used for electricity necessary for human life. However, when these hydrocarbon fuels are burned, carbon dioxide is generated and causes global warming. Therefore, in recent years, various proposals have been made to significantly reduce the consumption of these hydrocarbon fuels. ing. The most promising of these are hydrogen-fueled fuel cells.

The power generation principle of a fuel cell is a reaction opposite to the electrolysis of water, and oxygen gas and hydrogen gas are supplied to two electrodes sandwiching an electrolyte to generate electricity. FIG. 4 is a diagram showing an example of the structure of a polymer electrolyte fuel cell. The hydrogen (gas) conduit 17 through which hydrogen (H ₂ ) gas passes and supplies hydrogen gas to the fuel cell 21 and the conduit 19 through which unreacted hydrogen gas discharged from the fuel cell flows are two metal plates 11 and a metal plate. 12 (metal plywood 13) are put together to form. In the fuel cell 21, an anode electrode (fuel electrode) 25 and a cathode electrode (air electrode) 23 are arranged on both sides of the solid electrolyte 24, and a hydrogen supply line 26 is provided outside the anode electrode (fuel electrode) 25. An air supply line 22 is arranged outside the (air electrode) 23.

The conduit (air conduit) 18 that supplies air (O ₂ + N ₂ ) or oxygen (O ₂ ) and the conduit 20 through which water (H ₂ O) discharged from the fuel cell 21 and unreacted air flow are made of two metals. The plate 14 and the metal plate 15 (metal plywood 16) are put together to form. As shown in FIG. 4, the hydrogen conduit 17, its discharge conduit 19, the air conduit 18, and its discharge conduit 20 have a convex shape, so that when the metal plywoods 13 and 16 are stacked, a space is created between them. By arranging the fuel cell 21 in this space, a fuel cell module incorporating a large number of fuel cells can be manufactured. Fuel cells are alternately arranged in the vertical direction in the opposite direction, and one hydrogen conduit 17 enters the hydrogen supply lines 26 of the upper and lower hydrogen batteries 21, and unreacted hydrogen discharged from the hydrogen supply lines 26 is discharged. Enter conduit 19. Further, one air conduit 18 enters the air supply lines 22 of the upper and lower hydrogen batteries 21, and the water and unreacted air discharged from the air supply lines 22 enter the discharge conduit 20. In FIG. 4, the gas flow is indicated by the arrow symbol ⇒.

The phosphoric acid fuel cell can also be configured with the same structure as that of FIG. 4 by changing the solid electrolyte 24 in FIG. 4 to phosphoric acid (liquid electrolyte). In the case of the molten carbonate fuel cell as well, the solid electrolyte 24 in FIG. 4 is changed to the electrolyte (Li ₂ CO ₃ + K ₂ CO ₃ ), and the oxidant gas (O ₂ + CO ₂ ) only passes through the air conduit. , Can be configured with the same structure as in FIG. As described above, most of the fuel cells require a hydrogen conduit for supplying hydrogen, and a fuel module structure as shown in FIG. 4 can be produced by using two metal plates.

Hydrogen embrittlement and safety of metallic materials {Hydrogen energy system vol.22 No.2 (1997)}

As described above, in a hydrogen fuel cell, a hydrogen (gas) conduit through which hydrogen passes is indispensable, and stainless steel such as SUS304 is mainly used as the conduit material. In FIG. 4, the metal plates 11 and 12 constituting the hydrogen conduit 17 correspond to each other. However, when hydrogen (H ₂ ) gas comes into contact with the inner surface of stainless steel for a long period of time, a phenomenon (hydrogen brittleness) occurs in which hydrogen invades the stainless steel and makes the stainless steel brittle. In particular, it appears remarkably in the portion of stainless steel where stress is concentrated (for example, the corner of the hydrogen conduit 17 in FIG. 4). Since a fuel cell is expensive, it is necessary to extend the life of the fuel cell in order to reduce the cost. However, deterioration of the stainless steel due to hydrogen embrittlement hinders the extension of the life of the fuel cell. Further, in a fuel cell, heat is often generated by a chemical reaction when electricity is generated, so that the temperature of the hydrogen conduit also rises and hydrogen embrittlement is promoted. (Non-Patent Document 1)

The present inventor has discovered that hydrogen embrittlement can be prevented by adhering a carbon film to the surface of a stainless steel metal plate such as SUS304, and laser welding both sides of the concave portion of the two metal plates to pass hydrogen (hydrogen). (Gas) conduit) was applied to the fabrication. Specifically, it has the following features.
(1) The present invention is a method (manufacturing method) of welding two metal plates to form a space (called a hydrogen conduit) through which a gas containing hydrogen gas passes, and the surface of the metal plate inside the hydrogen conduit. It is characterized by forming a carbon film on the surface of the metal plate (called the inner surface of the metal plate) or the surface of the metal plate outside the hydrogen conduit (called the outer surface of the metal plate), and each of the two metal plates is a concave portion for the hydrogen conduit. And has a flat part, the concave part and the flat part of the two metal plates are combined, the flat part (called the welded part) around the concave part is laser welded along the concave part, and the concave part is used as a hydrogen conduit. It is characterized by doing.
(2) In addition to (1), the present invention forms minute irregularities on the metal surface (inner surface and / or outer surface of the metal plate) forming the carbon film by laser irradiation before forming the carbon film, and carbon. The film is characterized by being formed by a CVD method, a PVD method, or a plating method.

(3) In the present invention, in addition to (1) or (2), the structure of the laser-welded portion (referred to as the welded portion) of the two metal plates is one of the two metal plates. (Referred to as metal plate A), carbon film laminated on the inner surface of metal plate A (referred to as carbon film on metal plate A), and another metal plate in contact with the carbon film on metal plate A (referred to as metal plate B). Whether it is a carbon film (referred to as a carbon film on the metal plate B) and a metal plate B laminated on the inner surface, or a metal plate A, a carbon film on the metal plate A or a carbon film on the metal plate B, and a metal plate B. , Or a metal plate A and a metal plate B.
(4) In the present invention, in addition to (1) or (2), there are three laser welded parts (referred to as welded parts) on the flat portion of the metal plate on one side of each of the recesses, and the above three parts. One of the structures of the laser welded portion is one metal plate (metal plate A) of two metal plates, a carbon film laminated on the inner surface of the metal plate A (carbon film on the metal plate A), and the metal. A carbon film (carbon film on the metal plate B) and a metal plate B laminated on the inner surface of another metal plate (metal plate B) in contact with the carbon film on the plate A, and the three laser-welded portions. The other one of the structures of the metal plate A, the carbon film on the metal plate A or the carbon film on the metal plate B, and the metal plate B, and the remaining one of the structures of the three laser welded parts is , A metal plate A and a metal plate B.

(5) In the present invention, in addition to (1) to (4), when two metal plates are combined and laser welded, a plurality of convex portions of the metal plate serving as a hydrogen conduit on the laser irradiation side are connected to each other. Is pressed by a transparent jig, and a laser is irradiated to a welded portion (called a welded portion) of the metal plate through the transparent jig to melt-join the metal plate A and the metal plate B at the welded portion. The space (referred to as welding space A) including the area to be irradiated by the laser, which is surrounded by the transparent jig, the convex portion of the metal plate, and the metal plate, is characterized in that it is filled with the shield gas.
(6) In the present invention, in addition to (1) to (5), when two metal plates are combined and laser welded, a plurality of convex portions of the metal plates serving as hydrogen conduits on the side not irradiated with the laser are connected to each other. Is held down by a holding jig or a pedestal, and two metal plates are melt-joined at a portion to be welded (called a welded part) of the metal plate, and the holding jig or pedestal, a convex portion of the metal plate, and metal The space surrounded by the plates (called the welding space B) is filled with the shield gas, the pressure of the shield gas in the welding space is larger than the atmospheric pressure or the ambient pressure, and the shield gas is helium (He). It is characterized by being at least one gas selected from gas, argon (Ar) gas, neon (Ne) gas and nitrogen (N ₂ ) gas.

(7) In the present invention, in addition to (1) to (6), the carbon film on the outer surface of the metal plate on the laser irradiation side is formed after laser welding, and the carbon on the outer surface of the metal plate on the side not irradiated with the laser is formed. The film is formed after laser welding, and the metal plate is SUS304 or stainless steel or iron-based material.
(8) In the present invention, the metal plate surface structure of the hydrogen conduit, which is a space for passing a gas containing hydrogen gas produced by welding two metal plates, has a structure in which a carbon film is laminated on the surface of the metal plate. It is a hydrogen conduit characterized by being present, and has a structure in which a carbon film is laminated on the surface of a metal plate inside and / or outside the hydrogen conduit, and a structure in which carbon films are laminated on both surfaces of the metal plate. The carbon film is a CVD carbon film, a PVD carbon film or a plated carbon film, and the metal plate is SUS304 or a stainless steel or iron-based material.

In the present invention, since a CVD carbon film or the like is laminated on the inner and outer surfaces of a metal plate such as SUS304 (the inner and outer metal surfaces of the hydrogen conduit) constituting the hydrogen conduit, hydrogen (H ₂ ) in the hydrogen conduit penetrates into the metal plate. Can be prevented from doing so. As a result, hydrogen embrittlement can be suppressed and the life of the hydrogen conduit can be extended. Since the inner and outer surfaces of the metal plate are formed with a laser, the adhesion of the CVD carbon film or the like is also improved. Since the hydrogen conduit is formed by laser welding the outside of the convex portions of the two metal plates having the two convex portions, it is easy to manufacture. Since the convex portion can be pressed by the transparent plate material and the flat plate holding plate to ensure the contact between the two metal plates at the welded portion, the quality of the welded portion can be improved.

FIG. 1 is a diagram showing the structure and manufacturing method of the hydrogen conduit of the present invention. FIG. 2 is a perspective view of a work (work upper plate + work lower plate) including the hydrogen conduit of the present invention. FIG. 3 is a diagram showing another method of laser welding the work upper plate and the work lower plate of the metal plate on which the carbon film is laminated. FIG. 4 is a diagram showing an example of the structure of a polymer electrolyte fuel cell. FIG. 5 is a diagram showing an embodiment in which a work is pressed by using a work holding plate. FIG. 6 is a diagram showing an arrangement state of hydrogen conduits. FIG. 7 is a diagram showing a work plate having a carbon film formed on the front side (outer surface) of the work plate.

The present inventor has discovered that hydrogen embrittlement can be prevented by adhering a carbon film to the surface of a metal plate. In the hydrogen conduit of the present invention, a concave portion is formed on a metal flat plate (metal plate), and two metal plates having the concave portion formed are stacked so that the concave portions meet, and the flat portions on both sides of the concave portion are formed. By welding, a space through which hydrogen passes (since the space is a closed space like a pipe, it is also referred to as a hydrogen (gas) conduit or a hydrogen (gas) pipe) is created. FIG. 1 is a diagram showing the structure and manufacturing method of the hydrogen conduit of the present invention. The concave portion of the metal plate is formed by bending or deep drawing. As shown in FIG. 1A, the carbon film is formed on the metal surface after the concave portions 17 (17-1, 17-2) are formed on the metal plate 11 and then the metal plate surface (the side having the concave portions). ) Is formed with a carbon film 32. Alternatively, after the carbon film 32 is formed on the surface of the flat metal plate 11, the concave portion 17 can be formed on the metal plate 11 by bending or deep drawing. The materials of the metal plate are, for example, SUS304 and other various stainless steels, iron-based materials mainly composed of iron, aluminum and aluminum alloys, copper-based materials mainly composed of copper, zinc-based materials mainly composed of zinc, and nickel. It is a nickel-based material containing as a main component or a titanium-based material containing titanium (Ti) as a main component.

Examples of the method for forming a carbon film on the surface of a hydrogen conduit of the present invention include a chemical vapor deposition method (CVD method), a physical vapor deposition method (PVD method) such as sputtering and vapor deposition, and a plating method. Examples of the CVD method include a normal pressure CVD method using a hydrocarbon gas such as acetylene, methane and benzene, and a carbon source gas such as alcohol (for example, ethanol), a reduced pressure CVD method, a plasma CVD method, an optical CVD method and the like. The structure of the carbon film is graphene, carbon nanotube, diamond, diamond-like, amorphous, etc., and any structure is effective for hydrogen brittleness, but carbon nanotubes, diamond, diamond-like in particular have a dense and strong film. Therefore, it is suitable. Since the carbon source gas contains hydrogen, the CVD carbon film contains hydrogen. (Approximately 5 to 30 at%) Hydrogen contained in this CVD carbon film is present in the carbon film, but it is considered that it is also bonded to carbon, and the temperature at which the fuel cell generates heat (for example, 100 ° C.) ~ 800 ° C.), hydrogen does not separate from the carbon film and does not penetrate into the metal film. Further, it is difficult for hydrogen in the hydrogen conduit to penetrate into the carbon film, and in the case of the CVD film, hydrogen already exists in the film, and most of the hydrogen in the hydrogen conduit penetrates into the CVD carbon film. It's difficult to do. As a result, the CVD carbon film is considered to be particularly resistant to hydrogen embrittlement.

As the PVD carbon film, for example, a carbon target plate can be sputtered with Ar gas in a sputtering device to grow a carbon film on the surface of the metal plate. The metal plates (11, 12) may be flat plates or may have a concave portion 17. (Although it is described as concave here, it can also be described as convex because it is convex when viewed from the back side.) Naturally, it is necessary to arrange the concave portion 17 in the sputter device so that it faces the carbon target plate side. The metal plate (11, 12) may be rotated so that the thickness is uniform on the side surface and the bottom surface of the concave portion 17. If it is a 100% carbon carbon target plate, the carbon film laminated on the surface of the metal plate does not contain hydrogen, so the effect of suppressing the invasion of hydrogen like the CVD carbon film is small, but the laminated carbon film Since is dense and strong, hydrogen is suppressed from entering the metal side through the carbon film, and the hydrogen brittle phenomenon is considerably prevented. If hydrogen is pre-containing in the carbon target (for example, 10 to 40 at%), or if hydrogen gas is mixed with argon (Ar) gas, which is a sputter gas (for example, 1 to 10 Vol%), the surface of the metal plate Since hydrogen is incorporated into the carbon film laminated on the metal plate, the hydrogen intrusion prevention effect similar to that of the CVD carbon film can be increased, and the hydrogen embrittlement phenomenon of the metal plate can be significantly suppressed.

A carbon plating film can also be laminated on the surface of the metal plate. For example, LiCl-KCl and LiCl-KCl-CaCl ₂ are used as molten salts, CaC ₂ is added as a carbon source, and the mixture is heated at about 400 ° C. to 600 ° C., and a metal plate is used as a working electrode in the molten salt to counter electrode. It is also possible to laminate a plating film on the surface of a metal plate by using an aluminum plate. This carbon film can also enhance the hydrogen embrittlement resistance of the metal plate. In the case of carbon plating, even if the metal plate has a concave portion, the carbon film can be uniformly laminated on the bottom surface and the side surface of the concave portion. Alternatively, after laminating a carbon film on the surface of a flat metal plate by a plating method, a concave portion can be formed on the metal plate, or after forming a concave portion on a flat metal plate, a flat portion of the metal plate or A carbon plating film can also be laminated on the concave portion. After forming a concave portion on a flat metal plate, it is better to laminate a CVD carbon film, a PVD carbon film, and a carbon plating film on the flat portion or the concave portion of the metal plate to obtain carbon in the concave portion (particularly the corner portion). Since the internal stress of the film can be reduced, the reliability of the carbon film can be increased and the life of the carbon film can be extended.

When a CVD carbon film, a PVD carbon film, and a plated carbon film are laminated on a metal surface, the metal plate surface is irradiated with a laser to form minute irregularities, whereby the carbon film is formed on the metal plate surface. Adhesion can be improved. For example, it is preferable that the depth of the concave portion of the concave-convex structure is about 30 to 10 μm, the width is about 30 to 120 μm, and the convex portion has a chevron shape. The width of the convex portion is preferably about 5 to 50 μm. Due to such a shape, the contact area between the carbon film and the metal surface is increased, so that the adhesion strength between the metal plate and the carbon film is increased. The laser oscillator that generates the laser light is not particularly limited as long as a groove can be formed on the surface of the silicon substrate, and a known oscillator can be used. For example, a laser oscillator capable of melting a metal plate surface portion by laser light irradiation such as an excimer laser, a CO ₂ laser, or a YAG laser can be mentioned. The irradiation conditions of the laser beam are appropriately adjusted so that a groove having a desired shape can be formed. For example, conditions such as wavelength, frequency, and irradiation shape are adjusted so that the energy density is 4 × 10 ⁴ to 1 × 10 ⁶ W / cm ² .

As shown in FIG. 1A, a carbon film 31 is laminated on the surface of a metal plate 12 including a concave portion 17 (17-1) and a flat portion (this is referred to as a work upper plate 33) and a concave portion. 17 (17-2) and a metal plate 11 including a flat portion in which a carbon film 32 is laminated (this is called a work lower plate 34) and concave portions 17 (17-1, 2) are overlapped with each other. It is adjusted so that the closed space 17 is formed. Since the work upper plate 33 and the work lower plate 34 are work plates having the same shape on the front and back sides, the concave portion 17 (17-1, 2) and the other flat portions can be aligned almost completely. .. Although it is described as a closed space 17, it is a closed space in the left-right direction of FIG. 1, but as shown later (in FIG. 2), the closed space 17 is a hydrogen conduit through which hydrogen gas passes, so that the space is relative to the paper surface. The space extends in the almost vertical direction. When the hydrogen conduit 17 is used for a fuel cell as shown in FIG. 4, it may be arranged so as to surround the fuel cell.

Next, as shown in FIG. 1 (b), the work upper plate 33 and the work lower plate 34 (referred to as welded parts) 35 on the left and right of the concave portion 17 are irradiated with laser light 36 from above the work upper plate 33. Then, the work upper plate 33 and the work lower plate 34 are melt-joined at the welded portion 35. At the welded portion 35, the work upper plate 33 and the work lower plate 34 are in contact with each other by carbon films (31, 32). Since the melting point of the carbon film is about 3000 ° C to 3600 ° C (varies depending on the strength of the carbon bond), if the laser power is adjusted so that the temperature is higher than the above temperature at the portion where the carbon films come into contact with each other, the carbon film can be formed. Since the metal plate is melted and the metal plate is melted at the above temperature, the work upper plate 33 and the work lower plate 34 can be completely melt-bonded at the welded portion 35. Alternatively, since the carbon film is considerably thinner than the metal plate (for example, metal plate 1 mm, carbon film 1 to 10 to 100 μm), the laser power may be adjusted so as to melt the metal plate (particularly the work upper plate side). The carbon film dissolves in the metal plate, and the work upper plate 33 and the work lower plate 34 can be completely melt-bonded at the welded portion 35. In particular, in the case of stainless steel or iron-based materials such as SUS304, carbon is easily dissolved. Since the carbon film has good thermal conductivity, if the metal plate 12 on the work upper plate 33 side melts, the metal plate 11 on the contact portion side of the welded portion 35 on the work lower plate 34 side also melts, so that sufficient melt bonding is sufficient. Can be realized. When the metal plate is stainless steel SUS304, the melting point is about 1420 ° C. Therefore, if the laser power is adjusted so as to exceed this temperature and the laser is irradiated, the stainless plate 12 on the work upper plate 33 side and the work lower A part of the stainless steel plate 11 on the plate 34 side (upper side, that is, the contact portion side) is melted, and the carbon films 31 and 32 sandwiched between them are solid-solved in the molten stainless steel to form a solid-dissolved layer. And firmly melt-join.

FIG. 1C is a diagram showing a welding method when the structure of the welded portion 35 is changed. The welded portion 35-4 has the same structure as shown in FIG. 1 (b). The welded portion 35-1 removes the carbon film 31 of the work upper plate 33 on the laser irradiation side. Therefore, the structure of the welded portion 35-1 is a three-layer structure of the metal plate 12 (work upper plate 33 side) / carbon film 32 (work lower plate 34 side) / metal plate 11 (work upper plate 34 side). Therefore, as compared with the case of the structure of the welded portion 35-4, the laser power and the irradiation time can be slightly reduced due to the small amount of the carbon film, and the margin of the laser irradiation condition is large. The welded portion 35-2 removes the carbon film 32 of the work lower plate 34 on the opposite side to the laser irradiation. Therefore, the structure of the welded portion 35-2 is a three-layer structure of the metal plate 12 (work upper plate 33 side) / carbon film 31 (work upper plate 33 side) / metal plate 11 (work lower plate 34 side). Therefore, as compared with the case of the structure of the welded portion 35-4, the laser power and the irradiation time can be slightly reduced due to the small amount of the carbon film, and the margin of the laser irradiation condition is large. The welded portion 35-3 removes the carbon film 31 of the work upper plate 33 on the laser irradiation side and the carbon film 32 of the work lower plate 34 on the opposite side of the laser irradiation. That is, there is no carbon film at the welded portion 35-3. Therefore, since the structure of the welded portion 35-3 is a two-layer structure of the metal plate 12 (work upper plate 33 side) / metal plate 11 (work lower plate 34 side), the welded portions 35-1, 2, Compared with the case of the structure of 4, the laser power and the irradiation time can be reduced because the carbon film is eliminated, and the margin of the laser irradiation condition can be increased. At the welded portion 35-3, laser irradiation can be performed under substantially the same conditions as welding of metal plates.

Since a carbon film is required for the concave portion 17, a method for preventing or removing the carbon film at the welded portion 35 will be described. As an example, a region to be a welded portion of a metal plate is masked in advance, and then a carbon film is laminated. In the case of a CVD carbon film or PVD carbon film, if the carbon film is laminated in the masked state, the carbon film is also laminated in the masking region. Therefore, if the masking member is removed after laminating the carbon film, the carbon film in the masking region can be obtained. There is no carbon film in the region that is removed together with the masking member and becomes the welded part of the metal plate. For example, since the plasma CVD carbon film is laminated at, for example, about 400 ° C. to 800 ° C., the masking member needs to be a member that does not deform or react even at these temperatures. For example, when the metal plate is SUS304 stainless steel, a stainless tape (SUS304 or other) is attached to the area to be the welded part of the metal plate, the plasma CVD carbon film is laminated, and then the stainless steel. Just peel off the tape. In the case of a spatter carbon film, the sputter temperature is about 100 ° C or less. For example, if an aluminum tape is attached to the area to be the welded part of the metal plate, the sputter carbon film is laminated, and then the stainless tape is peeled off. good. If the spatter temperature is room temperature, plastic tape may be used instead of aluminum tape. When the masking tape is used, the carbon film also adheres to the side surface of the masking tape, so that when the masking tape is peeled off, the carbon film on the side surface (edge portion) of the boundary may also be peeled off. In order to prevent this, after laminating a carbon film on a metal plate, lightly etching the carbon film with oxygen (O ₂ ) plasma with the masking tape attached, the film quality of the carbon film on the side surface (edge) becomes flat. Since it is weaker than the portion, the carbon film on the side surface (edge portion) is etched at the initial stage of etching while the carbon film on the flat portion is hardly etched. When the carbon film on the side surface (edge part) is etched and taken out from the oxygen (O2) plasma device, the masking tape and the carbon film on the flat part are separated, so even if the masking tape is peeled off, the carbon film on the flat part becomes It can be prevented from affecting.

As another example, after laminating a carbon film on the entire surface of the metal plate, a portion other than the region to be the welded portion may be masked, and the exposed carbon film in the region to be the welded portion may be removed by etching. For example, an aluminum tape or a stainless tape may be attached to a portion other than the region to be a welded portion, a work may be arranged in a plasma etching apparatus, and the carbon film may be etched and removed by oxygen plasma. The carbon film is removed as CO or CO ₂ by oxygen plasma. Since the metal plate of the base material (for example, SUS304) is not etched by oxygen plasma, the carbon film existing in the region to be the welded portion can be completely removed. Also, since the aluminum tape and stainless tape of the masking material are hardly etched by oxygen plasma, if the aluminum tape and stainless tape of the masking material are peeled off after removing the carbon film, the carbon film will be formed in the part other than the welded part. A metal plate that exists and has no carbon film in the region to be a welded portion can be produced. When removing the carbon film in the region to be the welded part, it is sufficient that the carbon film exists in the concave part. Therefore, only the concave part is masked in the region other than the region to be the welded part (for example, a flat part). The carbon film can also be removed. Since the height of the gap in the portion where the carbon film is removed (this is also the thickness of the carbon film) is about 1 to 10 to 100 μm, this gap is immediately formed when the metal plate is melted by irradiation with laser light. Since it is filled, it does not affect the welding quality. Here, the welding quality means, for example, insufficient contact between work plates (upper plate, lower plate) at the welded portion, oxidation or the like at the welded portion, or insufficient laser welding conditions. This is a phenomenon in which the melt-bonding is not sufficient and the life of the joint is shortened, or the welding strength of the melt-joint is weak.

FIG. 1D is a diagram showing a method of irradiating a laser using a work holding plate that holds the work plate. In order to improve the quality of the laser welded portion 35, it is necessary that the upper and lower work plates (work upper plate and work lower plate) are in close contact with each other at the welded portion 35 during laser irradiation. Both the work upper plate 33 and the work lower plate 34 have an outwardly convex portion (that is, the concave portion 17 is turned inside out), and the heights of the plurality of convex portions are the same. By pressing the work upper plate 33 from above and the work lower plate 34 from below by pressing from above and below, the laser welded portion 35 can be brought into close contact with each other. The flat plate holding plate (also referred to as the work holding (upper) plate or (work upper plate) holding jig) 37 on the laser irradiation side (work upper plate 33 side) is transparent (transmittance) to the laser beam 36. (High) member (also referred to as a transparent plate, transparent plate material, or transparent jig). The flat plate holding plate (also referred to as a work holding lower plate or a (work lower plate) holding jig) 38 that holds the work lower plate 34 on the opposite side may be a member that securely holds the work lower plate 34. For example, a metal plate (for example, stainless steel such as SUS304), an iron-based material containing iron as a main component, various metal materials or a ceramic plate may be used, or a flat and non-deformable pedestal or base on which a work is placed may be used. As shown in FIG. 1D, the laser beam 36 irradiates the welded portion 35 through the transparent plate member 37 in a state where the work upper plate 33 and the work lower plate 34 are pressed from above and below to ensure that the welded portion is in contact with each other. , The work upper plate 33 and the work lower plate 34 are laser melt-bonded at the welded portion 35. As a result, the quality of the melt-bonding of the welded portion 35 is improved, and the closed space 17 serving as a hydrogen conduit can be completely sealed to the left and right outside, and a closed space having a long life can be produced. The transparent plate material 37 is preferably a material that is not damaged by laser light. For example, when a YAG laser is used, the transparent plate material 37 is preferably heat-resistant glass such as quartz, quartz glass, or borosilicate glass, or corundum (hereinafter referred to as quartz glass or the like). In the case of a carbon dioxide (CO ₂ ) laser, the transparent member is, for example, zinc selenium (ZnSe).

Since the space 39 between the hydrogen conduits 17 (17-1, 2) and the transparent work holding plate 37 is a space through which the laser beam 36 passes, it is called a welding space (laser irradiation side) 39. Since the welded portion 35 becomes hot due to laser irradiation, if the atmosphere of the welded space 39 is air, the welded portion 35 of the metal plate 12 of the work upper plate 33 exposed in the welded space 39 and its surroundings are oxidized. In particular, when the metal plate 12 is melted by laser irradiation, oxidation proceeds rapidly. As a result, the oxidized welded portion 35 is deteriorated, and the life of the work upper plate 33 is shortened. In addition, the welding quality at the welded portion 35 also deteriorates, and hydrogen in the hydrogen conduit 17 may leak from the welded portion 35. Therefore, the welding space 39 is set as a shield gas atmosphere so that the welding portion 35 is not oxidized even if the welding portion 35 is irradiated with a laser. When the hydrogen conduit 17 surrounds the welding space 39, the space is closed when the work upper plate 33 is pressed by the work holding plate 37. At this time, the work holding plate 37 is provided with a shield gas introduction hole 71. , The shield gas can be introduced into the welding space 39 from the shield gas introduction hole 71 to make the welding space 39 a shield gas atmosphere. If the work holding plate 37 is also provided with the shield gas discharge hole 72, the air existing in the welding space 39 before the work holding plate 37 presses the work upper plate 33 is discharged from the shield gas discharge hole 72 to create the welding space 39. It can be completely filled with shield gas.

Shield gas (also called assist gas) includes inert gas (for example, rare gas such as helium (He) gas, argon (Ar) gas, neon (Ne) gas, nitrogen (N ₂ ) gas), and carbon. Examples include system gases (for example, CO ₂ and hydrocarbon gas), other gases (for example, H ₂ ), and mixed gases thereof. Alternatively, even if the welding space 39 is made low pressure (atmospheric pressure or less or outside pressure or less) or vacuum, the air in the welding space 39 disappears, so that oxidation of the metal plate 12 at the time of laser irradiation can be prevented. For example, if a vacuum pump is connected to the holes 71 and 72 to release air from the welding space 39, the welding space 39 can be made low pressure or vacuum. When the welding space 39 is made low pressure or vacuum, the work holding plate 37 is pushed from the outside by atmospheric pressure or outside pressure, so that the work upper plate 33 is also pushed from above, and the adhesion between the work lower plate 34 and the work upper plate 33 is achieved. Will also get better. When the work holding plate 37 is transparent to visible light (quartz glass or the like corresponds to this), the alignment of the work upper plate 33 and the work lower plate 34 and the welded portion can be confirmed with the naked eye or a magnifying glass. It is also possible to improve the alignment accuracy of the upper plate 33 and the work lower plate 34 and accurately irradiate the welded portion with a laser.

The space 40 between the hydrogen conduits 17 (17-1, 2) and the work holding plate 38 is not a space through which the laser beam 36 passes, but it also faces the welding region, so this is also a welding space (laser). (Back side of irradiation) 40. The welded portion 35 of the metal plate 11 of the work lower plate 34 on the side opposite to the laser irradiation side and its surroundings also become hot during laser welding. Therefore, if the atmosphere of the welding space 40 is air, the welded portion 35 and its surroundings The surrounding metal plate 11 also oxidizes. In order to prevent this oxidation, it is desirable that the welding space 40 also has a shield gas atmosphere. When the hydrogen conduit 17 surrounds the welding space 40, the space is closed when the work lower plate 34 is pressed by the work holding plate 38. At this time, the work holding plate 38 is provided with a shield gas introduction hole 73. , The shield gas can be introduced into the welding space 40 from the shield gas introduction hole 73 to make the welding space 40 a shield gas atmosphere. If the work holding plate 38 is also provided with the shield gas discharge hole 74, the air existing in the welding space 40 before the work holding plate 38 presses the work upper plate 34 is discharged from the shield gas discharge hole 74 to create the welding space 40. It can be completely filled with shield gas. When the work holding plate 38 is a pedestal, a base, or the like, a line capable of introducing the shield gas from the pedestal or the base into the welding space 40 and a line for discharging the shield gas may be provided. Even if the welding space 40 is made low pressure (atmospheric pressure or less or outside pressure or less) or vacuum, the air in the welding space 40 disappears, so that oxidation of the metal plate 11 at the time of laser irradiation can be prevented. (Since the metal plate 11 becomes hot, oxidation is promoted when there is air.) For example, if a vacuum pump is connected to the holes 73 and 74 and the air in the welding space 40 is removed, the welding space 40 is reduced to low pressure or vacuum. can do. When the welding space 40 is made low pressure or vacuum, the work holding plate 38 is pushed from the outside by atmospheric pressure or outside pressure, so that the work lower plate 34 is also pushed from above, and the adhesion between the work lower plate 34 and the work upper plate 33 is achieved. Will also get better.

As a method of pressing the work upper plate 33 with the work holding (upper) plate 37, a method of pressing from above the work holding (upper) plate 37, for example, a method of pressing with a press or a method of pressing the work holding (upper) plate 37 from above to the whole. There is a method of applying, but various other methods can also be adopted. As a method of pressing the work lower plate 34 with the work holding (lower) plate 38, a method of pressing from below the work holding (lower) plate 38, for example, a method of pressing with a press or a method of pressing the work holding (lower) plate 38 from below to the whole. There is a method of applying, but various other methods can also be adopted. In the case of a pedestal or a base, the work lower plate 34 can be pressed by the reaction force from the work holding (upper) plate 37. By increasing the pressure of the shield gas introduced into the welding space 39, the work upper plate 33 can be pressed at the welded portion 35 (in this case, the entire flat portion of the work upper plate 33 is pressed), and at the welded portion 35. The work upper plate 33 and the work lower plate 34 can be reliably brought into close contact with each other, and the welding quality can be improved. Similarly, by increasing the pressure of the shield gas introduced into the welding space 40, the work lower plate 34 can be pressed at the welded portion 35 (in this case, the entire flat portion of the work lower plate 34 is pressed), and welding is performed. The work upper plate 33 and the work lower plate 34 can be reliably brought into close contact with each other at the portion 35, and the welding quality can be improved. When increasing the pressure in the welding space, it is necessary to press the work holding plate from the outside with a force equal to or higher than the pressure in the welding space so that the work holding plate does not come off.

There is also a method of arranging the entire members to be welded of the work upper plate 33 and the work lower plate 34 in a shield gas atmosphere. For example, the entire body including the laser device may be placed in a container in a shield gas atmosphere and laser irradiation may be performed. Alternatively, the work upper plate 33 and the work lower plate 34, the work holding upper plate 33 and the work holding lower plate 34 are placed in the container having a lid whose upper surface is transparent to the laser beam, and the inside of the container is filled with a shield gas atmosphere. Then, the laser beam is applied to the work through the transparent lid. When the convex hydrogen conduit 17 surrounds the welding spaces 39 and 40, the welding spaces 39 and 40 become a closed space when the work plates 33 and 34 are pressed by the work holding plates 37 and 38, so that the shield gas However, when the convex hydrogen conduit 17 does not surround the welding spaces 39 and 40 at all, when the work plates 33 and 34 are pressed by the work holding plates 37 and 38. Welding spaces 39 and 40 are not closed spaces. At that time, the welding spaces 39 and 40 can be filled with the shield gas by the method of arranging the entire members to be welded of the work upper plate 33 and the work lower plate 34 in the shield gas atmosphere. As another method, if a part of the work holding plates 33 and 34 is shaped so as to fit the flat portions of the work upper plate 33 and the work lower plate 34, the work holding plates 37 and 38 can be used to form the work plates 33 and 34. When pressed, the welding spaces 39 and 40 can be closed spaces.

FIG. 5A is a diagram showing another embodiment in which the work is pressed by using the work holding plate. A work holding member is attached to the work holding plate, and the work is actually held by the work holding member instead of the work holding plate. For example, the work holding upper plate 37 is a flat flat plate (transparent plate), and the work holding member 81 for holding the hydrogen conduit 17 and the flat portion of the work upper plate 33 is attached to the work holding upper plate 37. .. The work holding member 81-1 is a member having a concave shape that matches the convex shape of the hydrogen conduit 17-1, and the convex portion of the hydrogen conduit 17-1 is inserted into the concave portion of the work holding member 81-1. When the work holding upper plate 37 is pushed from above, the work holding member 81-1 can press the convex hydrogen conduit 17 portion of the work holding plate 33. Since the lower portion of the work holding member 81-1 is also in contact with the flat portion of the work upper plate 33, the flat portion of the work upper plate 33 can also be pressed. Since the portion of the lower part of the work holding member 81-1 that is in contact with the flat portion of the work upper plate 33 is close to the welded portion 35, welding is performed as compared with the case where the work upper plate 33 is pressed only by the work holding upper plate 37. The work upper plate 33 and the work lower plate 34 at the portion 35 can be brought into close contact with each other, and as a result, the welding quality of laser welding can be improved. The work holding member 81-2 also has the same effect as the work holding member 81-1. The work holding member 81-3 has a shape and a size that does not come into contact with the hydrogen conduit 17 but comes into contact with the flat portion of the work upper plate 33, and the work holding members 81-1 and 2 are attached to the work upper plate 33. When fitted into the hydrogen conduit portion, it comes into contact with the flat portion of the work upper plate 33. Then, when the work holding upper plate 37 is pushed, the work holding member 81-3 can press the flat portion of the work holding upper plate 33. If the work holding member 81-3 is arranged close to the laser welded portion 35, the portion of the lower part of the work holding member 81-3 that is in contact with the flat portion of the work upper plate 33 is close to the welded portion 35. Compared with the case where the work upper plate 33 is pressed only by the pressing upper plate 37, the work upper plate 33 and the work lower plate 34 at the welded portion 35 can be brought into close contact with each other, and as a result, the welding quality of laser welding can be improved. it can.

The work holding lower plate 38 is a flat flat plate, but the work holding lower plate 38 also has a shape suitable for the convex shape of the hydrogen conduit 17 on the work holding members 82-1 and 2 and the flat portion of the work lower plate 34. A work holding member 82-3 that comes into contact is attached. The actions and effects of the work holding members 82-1 and 2 and 3 are the same as the actions and effects of the work holding members 81-1 and 2 and 3, but the work upper plate 33 and the work lower plate 34 are formed from the vertical direction. As they are pressed, their effects are further enhanced. When the work holding members 81-1, 2 and 3 and the work holding members 82-1 and 2 and 3 as shown in FIG. 5A are used, welding spaces 39 and 40 are provided between the work holding members. Therefore, the welding space 39 or 40 can be a closed space surrounded by the work holding plates 37 and 38, the work holding members 81 and 82, and the work plates 33 and 34. Therefore, the welding spaces 39 and 40 can be filled with the shield gas by providing the work holding plates 37 and 38 and the work holding members with shield gas introduction holes and their discharge holes connected to the welding spaces 39 and 40, and welding. It is also easy to increase the pressure in the space. That is, if the pressure in the welding space is higher than the pressure outside the work holding member (for example, atmospheric pressure) or the ambient pressure, the work plates are pressed at the welded portion and the work plates (work upper plate and work lower plate) come into contact with each other. Can be ensured and the welding quality can be improved. Alternatively, even if the welding spaces 39 and 40 are made low pressure or vacuum, the above-mentioned effect can be obtained.

There are a plurality of hydrogen conduits 17, and the upper surface (or lower surface) of the plurality of hydrogen conduits 17 comes into contact with the work holding members 81 and 82 attached to the work holding plates 37 and 38, but the height of the hydrogen conduit 17 is high. If the hydrogen conduit 17 varies, it is possible that the work holding members 81 and 82 do not come into contact with each other. In particular, quartz glass or the like used for the work holding upper plate has almost no flexibility, which poses a problem (of course, if the variation in the hydrogen conduit is reduced, this problem also becomes smaller). Therefore, if the material of the work holding member is a flexible material, the work holding member can be brought into contact with the hydrogen conduit even if the height of the hydrogen conduit 17 varies. Examples of the flexible material include rubber, elastic plastic, flexible metal and alloy, which can be deformed (expanded and contracted) in the height direction. Since the laser welded part becomes hot, a heat-resistant material is desirable in the case of rubber or elastic plastic. The same applies to the case of contacting the flat portion of the work plate such as the work holding member 81-3 or 82-3, and by using these as flexible materials, the contact between the work holding member and the work plate can be easily ensured. Can be realized. It should be noted that it is necessary to select the flexible material and the height variation of the hydrogen conduit so that the work plate can be pressed when the flexible material is pressed to some extent. Further, by using a flexible material for the work holding member, a gap can be eliminated, so that the degree of sealing of the welding space is remarkably improved.

Even if a flexible material is used for the portion where the work holding member comes into contact with the work plate, there is a certain effect. For example, there is also a method in which the main body of the work holding member is made of quartz or the like or metal, and a flexible material is attached to the contact portion with the work plate. FIG. 5B is a diagram showing still another embodiment in which the work is pressed by using the work holding plate. In FIG. 5B, the work holding members 83 and 84 are arranged only on the convex portion of the hydrogen conduit 17 which is the convex portion of the work plate, and the material of these work holding members 83 and 84 is used as a flexible material. Is. That is, the work holding member 83 is arranged at the portion of the work holding upper plate that contacts the convex portion of the hydrogen conduit 17, and the work holding member 84 is arranged at the portion of the work holding lower plate that contacts the convex portion of the hydrogen conduit 17. The shape of the work holding members 83, 84 may be a simple rectangular parallelepiped shape, and the work holding members 83, 84 may be in contact with the hydrogen conduit 17, so that the alignment is easy (for example, larger than the upper surface of the convex portion of the hydrogen conduit 17). If the work holding members 83 and 84 are manufactured and attached to the work holding members 83 and 84, the work holding members 83 and 84 always come into contact with the upper surface of the convex portion of the hydrogen conduit 17), so that the manufacturing cost is considerably reduced. Since the work holding members 83 and 84 are flexible members, the upper surface (or lower surface) of the hydrogen conduit 17 can be pressed by the work holding plates 37 and 38 even if the height of the hydrogen conduit 17 varies slightly. The members 83 and 84 can come into contact with the flexible member and press the work plate.

FIG. 2 is a perspective view of a work (work upper plate + work lower plate) 60 including a hydrogen conduit of the present invention. The concave portions of the work upper plate 33 and the work lower plate 34 are combined to form a hydrogen conduit 17. The work upper plate 33 and the work lower plate 34 are laser-welded at the welded portion 35, and the hydrogen conduit 17 becomes a closed space. On the surface of the work upper plate 33, the welded portion 35 appears linearly as a welding line 61. That is, the laser scans the work upper plate 33 to make the hydrogen conduit 17 a closed space, and a welding line 61 is formed. Although the welding line 61 is drawn in a straight line in FIG. 2, it may be formed in a curved line depending on the arrangement state of the hydrogen conduit 17. At the welded portion 35, it is preferable that the welded portion ends inside the metal plate 11 of the work lower plate 35 and does not penetrate the metal plate 11. This is because the work may be deformed if the welded portion penetrates the metal plate 11. The portion of the hydrogen conduit 17 is a convex portion 62 (work upper plate 33 side) and a convex portion 63 (work lower plate 34 side), and a concave portion is formed between the convex portions 62, and the bottom portion of the concave portion is a flat surface 64. When manufacturing a fuel cell, the hydrogen conduit-containing substrates 60 are stacked. That is, the convex portion 63 (work lower plate 34 side) is arranged on the convex portion 62 (work upper plate 33 side), and the fuel cell is arranged on the flat surface 64 of the space formed by the concave portion between them. To go. Hydrogen (H ₂ ) gas or air (in this case, it should be called an air conduit, but for convenience, a hydrogen conduit) is supplied from a part of the side surface 65 of the hydrogen conduit 17 to the fuel cell, and the side facing the fuel cell. It is discharged to the hydrogen conduit (in this case, it should be called an exhaust conduit or an exhaust conduit, but for convenience, a hydrogen conduit), during which charge is exchanged and electricity is generated.

FIG. 3 is a diagram showing another method of laser welding the work upper plate and the work lower plate of the metal plate on which the carbon film is laminated. The structure with and without the carbon film is shown in FIG. 1 (c), and FIG. 1 (b) shows laser welding of the work upper plate and the work lower plate having the same carbon film structure under the same conditions. .. In FIG. 3, different carbon film structures are formed on the work upper plate and the work lower plate and laser welded. For example, three welded parts 51, 52, and 53 are provided on the right side of the hydrogen conduit 17 (17-1), and the structure of the welded parts 51 has a carbon film on both the work upper plate and the work lower plate, and next to them. The structure of the welded portion 52 is a structure in which the work upper plate has a carbon film but the work lower plate has no carbon film, and the structure of the welded portion 53 on the outside thereof has no carbon film on both the work upper plate and the work lower plate. It is a structure. The diameter of the laser beam can be narrowed down to about 0.1 mm to 1 mm, so if the laser irradiation conditions are adjusted, the welded parts can be separated from each other by about 1 mm to 3 mm to perform laser welding without interfering with the neighbors. be able to. Considering the error of the laser irradiation position, it is sufficient to separate the adjacent welded parts by about 5 mm to 1 cm. In this way, three welded parts are arranged at a distance that does not interfere with each other, and laser beams 41, 42, and 43 whose irradiation conditions are adjusted according to the conditions of each carbon structure are irradiated. Each weld is melt-joined. By laser welding at three locations in this way, even if there is insufficient bonding at one location, it can be supplemented by the other, and the hydrogen conduit 17 (17-1) can be reliably closed, and hydrogen can be used. Hydrogen does not leak from the conduit.

Welding sites 54, 55, and 56 are also provided on the left side of the hydrogen conduit 17 (17-2), and the structure of the welding sites 54 has a carbon film on both the work upper plate and the work lower plate, and welding next to them. The structure of the portion 55 is a structure in which the work upper plate has no carbon film and the work lower plate has a carbon film, and the structure of the welded portion 53 on the outside thereof is a structure in which neither the work upper plate nor the work lower plate has a carbon film. is there. In this case as well, three welded parts are arranged at a distance that does not interfere with each other, and the laser beams 44, 45, and 46 whose irradiation conditions are adjusted according to the conditions of each carbon structure are irradiated. Each weld is melt-joined. As shown in FIG. 3, when three welding sites are arranged, a structure having both carbon films near the hydrogen conduit 17 and a structure having only one carbon film in the middle portion, and welding on the outside. The site should have a structure without both carbon films. This is because the welding conditions become strict in the case of a structure having a carbon film, and even if welding is insufficient at the welding sites 51 and 54 near the hydrogen conduit 17, welding is sufficiently performed at the next welding sites 52 and 54. Further, welding can be reliably performed at the outer welded portions 53 and 55. Compared with the case of welding at one place around the hydrogen conduit 17 as shown in FIG. 1, the reliability is significantly improved in that the hydrogen conduit 17 can be surely made into a closed space by the method shown in FIG. Can be made to. If there is a margin, the adjacent welded portion may be larger than the above-mentioned separation distance.

The welded portion 57 is such that three types of carbon film structures are arranged in close proximity to each other and melt-bonded at each of the three types of welded portions with a single laser irradiation 47. The three types of carbon film structures are structures in which both carbon films are present on the side close to the hydrogen conduit 17 (17-1), the intermediate portion is a structure in which the work upper plate has no carbon film, and both outsides are carbon. The structure has no membrane. By properly adjusting the laser irradiation conditions, it is possible to perform melt bonding at each of the three types of carbon film structure parts with a single irradiation, achieving good bonding with a narrow width and creating a closed space without hydrogen leakage. Hydrogen conduit 17 (17-1) can be made. The welded portion 58 also has three types of carbon film structures arranged close to each other, and is fused and bonded at each of the three types of welded portions by one laser irradiation 48. The three types of carbon film structures are structures in which both carbon films are present on the side close to the hydrogen conduit 17 (17-2), the intermediate portion is a structure without a carbon film on the lower plate of the work, and both outsides are carbon. The structure has no membrane. By properly adjusting the laser irradiation conditions, it is possible to perform melt bonding at each of the three types of carbon film structure parts with a single irradiation, achieving good bonding with a narrow width and creating a closed space without hydrogen leakage. Hydrogen conduit 17 (17-2) can be made. When laser welding a work whose hydrogen conduit is covered with a carbon film in this way, by arranging three types of carbon film structural parts in close proximity, it is possible to reliably melt and join with a single laser irradiation, and laser welding work. It can also improve sex. In the case of the welded portions 57 and 58, if the distance from the hydrogen conduit 17 is about 1 to 5 mm or more, the hydrogen conduit 17 will not be affected during laser welding. In addition, the region without both carbon films is about 0.5 mm to 2 mm, the region without one of the carbon films immediately next to it is about 0.5 mm to 2 mm, and the region without carbon films immediately next to both is about 0.5 mm to. It may be 2 mm, and the welded portion region may be about 1.5 mm to 8 mm in total. Although various structures have been described in FIG. 3, the workability is better when the workability for producing the carbon film structure is taken into consideration and the laser irradiation conditions are smaller. Therefore, one of the structures is adopted. If all welds have the same structure, the quality level will be stable.

In FIG. 2, since the hydrogen conduits (one is the line through which hydrogen or air flows and the other (the opposite side) is the discharge line) run in parallel, the fuel cells are lined up on the flat surfaces of the hydrogen conduits. Will be placed in. Therefore, the welding line 61 is straight along the hydrogen conduit. However, the welding lines 61 may be connected to each other at the end point to form a closed curve. By making it a closed curve, the two metal plates can be reliably joined to each other. In this case, gas (hydrogen or air) flows from one side of the hydrogen conduit 17 and exits from the other side. FIG. 6 is a diagram showing a method of arranging another hydrogen conduit. FIG. 6 is drawn in a plane so that the arrangement state of the hydrogen conduit can be understood. The hydrogen conduits 95 and 96 are arranged so as to form a U-shape, and are arranged so as to be partially aligned with the adjacent hydrogen conduits (95 and 96). If 95 is a hydrogen conduit (in the case of air, it may be called an air conduit), 96 is its discharge conduit. At the end point of the U-shape, the hydrogen conduits 95 and 96 run close to each other in parallel, and the welding line 92 runs between them. The portion 97 surrounded by a U-shape is an area where the fuel cell is arranged. A welding line 91 is arranged in the portion 97 surrounded by the U shape so as to be surrounded by the hydrogen conduits 95 and 96. Here, since the welding line 91 has a closed curve, the laser irradiation can be described with a single stroke. The welding line 92 connects these welding lines 91 to each other. The hydrogen conduits 95 and 96 are sandwiched between the welding lines 91 and 92 to form a closed space, and hydrogen or the like does not leak to the outside. When irradiating the laser at three places as shown in FIG. 3, the number of welding lines is three. If there are two places, there are two. Since FIG. 6 shows a part of the fuel cell module, a fuel cell module equipped with a larger number of fuel cells can be manufactured by connecting a large number of the fuel cell modules. As can be seen from FIG. 1, since these can be stacked in the vertical (height) direction, a fuel cell module equipped with a larger number of fuel cells can be manufactured. By arranging the hydrogen conduits in a U shape as shown in FIG. 6, a large number of fuel cells can be arranged, and since each fuel cell is independent, one fuel cell may fail. Even if it stops working, it does not affect other fuel cells, so a highly reliable fuel cell (module) can be realized.

Although the work holding plate 37 has been described as a transparent member, the entire work holding plate 37 does not necessarily have to be transparent. It suffices if the part through which the laser light passes is at least transparent. For example, a work holding plate in which a transparent member, for example, a plate such as quartz glass is arranged only in a portion through which laser light passes, and other materials such as stainless steel such as SUS304 or an iron-based material containing iron as a main component. It may be a metal plate such as an aluminum-based material or a copper-based material, or various plastic materials such as polypropylene and acrylic. Alternatively, a work holding plate having a hole in a portion through which the laser beam passes may be used. In the case of a work holding plate with holes, it is difficult to completely seal the welding space, but the entire area including the work holding plate may be placed in a container that can be filled with shield gas, or the entire laser device may have a shield gas atmosphere. There is also the method of. Further, although the work holding plate 37 is described as a flat plate, if the lower surface of the work holding plate in which the work holding plate 37 contacts the plurality of hydrogen conduits 17 has the same height at the plurality of portions (or of the hydrogen conduit). The work holding plate 37 does not necessarily have to be a flat plate (as long as the various parts of the work holding plate 37 can contact the plurality of hydrogen conduits at almost the same time depending on the height). In other words, when described as a flat plate in the present invention, such a case is also included. Further, in FIG. 5A, the work holding members 81 and 82 that match the shape of the hydrogen conduit 17 are in contact with the flat portions of the work plates 33 and 34, but only the upper portion matches the shape of the hydrogen conduit 17. It has a shape, and the lower portion does not necessarily have to be in contact with the flat portions of the work plates 33 and 34. The same applies to the work holding lower plate.

The thickness of the work top plate may be comparatively thick as long as the laser beam passes through it. For example, it may be 1 mm to 1 cm or more. The thickness of the work lower plate is not particularly limited, but it is easy to manufacture if it can be replaced with the work upper plate. The height of the hydrogen conduit can be selected according to the size of the fuel cell. However, in the present invention, as shown in FIG. 4, the height of the hydrogen conduit increases depending on the size of the fuel cell. If it becomes too high, the amount of hydrogen flowing through the conduit will increase, so it is better to set the height so that the amount of hydrogen required for the fuel cell can be secured. In that case, a dummy may be attached to the upper surface of the hydrogen conduit in order to match the height of the hydrogen conduit with the size of the fuel cell. However, this dummy is not necessary for laser welding. Further, if the structure of the fuel cell is devised, this dummy can be eliminated, and it may be appropriately changed depending on the fuel cell. The thickness of the work holding upper plate needs to be a thickness that can withstand the holding strength, but in the case of quartz or quartz glass, it may be about 0.1 mm to 1 cm or more. The thickness must be sufficient to withstand the pressure of the work holding lower plate, but in the case of a stainless steel plate, it may be about 1 mm to 1 cm or more. The widths (vertical and horizontal) of the work plate and the work holding plate may be appropriately changed according to the size of the fuel cell. However, it is natural to change the thickness according to their size so that they are not deformed. Further, since the laser beam needs to be melted to the contact portion between the work upper plate and the lower plate, when the work plate is thick, the thickness of the welded portion of the work plate (particularly the work upper plate) is reduced (for example, the groove portion). You also need to put it.

FIG. 7 is a diagram showing a work plate having a carbon film formed on the front side (that is, the outer surface instead of the inner surface) of the work plate. As can be seen from FIGS. 2 and 4, the fuel cell 21 is arranged on the flat portion 64 on the outer surface of the work (plate) 60, and hydrogen or the like flows through the hydrogen supply line 26. That is, hydrogen or the like may come into contact with the outer surface of the work (plate) 60. Since the outer surface side of the work (plate) 60 shown in FIG. 1 or the like is a metal plate 11 or a metal plate 12, the outer surface of the work (plate) 60 when the fuel cell generates heat and the temperature rises. There is a possibility that hydrogen diffuses into the metal plate from the (outer) surface side of the metal plate 11 or the metal plate 12 to cause hydrogen brittleness. Therefore, as shown in FIG. 7, a carbon film is also laminated on the outer surfaces of the metal plate 11 and the metal plate 12. The carbon film can be formed by the same method as the inner surface side of the metal plate 11 or the metal plate 12, that is, the CVD method, the PVD method, and the plating method. After laminating the carbon films 85 and 86 on both sides (the side that becomes the outer surface and the side that becomes the inner surface) of the metal plate 11 and the metal plate 12, the metal plate 11 and the metal plate 12 are formed in the same manner as in the method shown in FIG. Align the recesses so that they fit, and irradiate the laser. Since the carbon film is thin, when the laser beam enters the metal plate through the carbon film and the metal plate melts, the carbon film also dissolves in the metal. Alternatively, the carbon film at the welded portion 35 on the outer surface of the work (particularly the outer surface of the metal plate 12 on the side irradiated with the laser) may be removed in advance. In this case, the work upper plate 33 has a structure in which carbon films 31 and 85 are formed on both surfaces of the metal plate 12, and the work lower plate 34 has carbon films 32 and 86 formed on both surfaces of the metal plate 11. The structure is as follows.

Similar to the carbon films 31 and 32, the carbon films 85 and 86 can be laminated on the surface of the metal plate before forming the concave (convex when viewed from the opposite side) portion 17 on the metal plate. It can also be laminated later. Since the thickness of the carbon films 85 and 86 is preferably about 10 μm to 100 μm or less, the laser beam 36 penetrates the carbon film 85 and melts the metal plates 12 and 11 (partially desirable) at the welded portion 35 to melt the metal plate 12 And 11 can be welded, but the carbon film 85 at the welded portion 35 may be removed before laser irradiation. The method for removing the carbon film may be the same as the method described for the welded portions 35-1, 2 and 3 in FIG. 1 (c) described above. Alternatively, the carbon film 85 at the welded portion 35 may be irradiated with a laser to remove the carbon film under conditions that do not melt the metal plate 12. The carbon film 85 is heated by laser irradiation and reacts with oxygen in the air to become CO or CO ₂ , which is removed. Even if the carbon film 31 is not removed, the carbon film 85 is dissolved in the metal plate 12 after laser irradiation, so that the carbon film 85 on the metal plate 12 disappears at the welded portion 35, and hydrogen invades from this portion. there's a possibility that.

Therefore, as shown in FIG. 1, the carbon film 85 may be formed on the surface of the metal plate 12 after laser welding without forming the carbon film 85 on the outer surface of the metal plate 12. The work after welding (60 in FIG. 2) may be set in a CVD device, a PVD device, or a plating device, and a carbon film may be laminated. According to this method, a carbon film can be uniformly formed on the entire surface (convex portion, flat portion, etc.) of the metal plate 12 after laser welding. In particular, since the carbon film can be laminated on the surface of the metal plate 12 at the welded portion 35, hydrogen can be prevented from entering the metal plate, and as a result, the occurrence of hydrogen embrittlement can be prevented. Since the metal plate 11 side is not irradiated with the laser, there is no particular problem even if the carbon film 32 is laminated before the laser irradiation, but the carbon film 86 is formed after the laser irradiation without forming the carbon film 32 before the laser irradiation. It may be laminated.

As described in detail above, the hydrogen conduit in which the carbon film of the present invention is laminated on the inner surface has high hydrogen embrittlement resistance, and can improve the life and reliability of the hydrogen conduit. The hydrogen conduit is made by laser welding two metal plates, but good welding quality can also be obtained by using the work holding plate of the present invention. The hydrogen conduit produced by using the present invention can be used for a fuel cell, but can greatly contribute to extending the life of the fuel cell. Although the cooling line is omitted for convenience in FIG. 4 as an example of the fuel cell, a cooling line can be manufactured by the same method as the method for manufacturing the hydrogen conduit of the present invention and incorporated into the fuel cell shown in FIG. .. For example, after the conduit is made, the flat portion of the metal plate can be hollowed out and incorporated between the hydrogen conduit 17 and the air conduit 18. Examples of the cooling method include a method of flowing cooling water and a method of flowing cooling gas (for example, cooled CO2 or cooled inert gas). Further, the hydrogen conduit 17 and the air conduit 18 can be crossed perpendicularly to each other. As described above, by using the hydrogen conduit of the present invention, it is possible to cope with various sizes and structures of fuel cells. Further, the fuel cell has various structures other than the structure shown in FIG. 4, but since the hydrogen conduit is indispensable in any structure, the hydrogen conduit of the present invention can be adopted. It goes without saying that the content can be applied to the other part of the specification without any contradiction as to the fact that the content described and explained in the specification can be applied to the other part without contradiction. In addition, it is natural that the contents of the examples and embodiments described in the present application document can be used in combination with the contents of other examples and embodiments. Further, it goes without saying that the embodiment is an example and can be modified in various ways without departing from the gist, and the scope of rights of the present invention is not limited to the embodiment.

The hydrogen conduit produced by laminating a carbon film on the inner surface of the present invention by laser welding can also be used for a hydrogen gas pipe other than a fuel cell and a container for accommodating hydrogen.

11 ... Metal plate, 12 ... Metal plate, 17 ... Hydrogen conduit, 31 ... Carbon film, 32 ... Carbon film, 33 ... Work upper plate, 34 ... Work lower plate, 35 ... (laser) welded part, 36 ... laser light, 37 ... transparent plate material (work holding upper plate), 38 work holding lower plate, 39 ... welding space (laser irradiation side), 40.・ ・ Welding space (back side of laser irradiation), 71 ・ ・ ・ Shield gas introduction hole, 72 ・ ・ ・ Shield gas discharge hole

Claims (21)

It is a method of welding two metal plates to form a space (called a hydrogen conduit) through which a gas containing hydrogen gas passes, and a carbon film is formed on the surface of the metal plate (called the inner surface of the metal plate) inside the hydrogen conduit. A method for producing a hydrogen gas conduit, which comprises forming. The method for producing a hydrogen gas conduit according to claim 1, wherein a carbon film is formed on the surface of the metal plate (referred to as the outer surface of the metal plate) which is the outside of the hydrogen conduit. The two metal plates each have a concave portion and a flat portion for a hydrogen conduit, and the concave portion and the flat portion of the two metal plates are combined to form a flat portion (called a welded portion) around the concave portion. The method for producing a hydrogen gas conduit according to claim 1 or 2, wherein the concave portion is formed into a hydrogen conduit by laser welding along the above. Any of claims 1 to 3, characterized in that minute irregularities are formed on the metal surface (inner surface and / or outer surface of the metal plate) on which the carbon film is formed by laser irradiation before the formation of the carbon film. The method for producing a hydrogen gas conduit according to. The method for producing a hydrogen gas conduit according to any one of claims 1 to 4, wherein the carbon film is formed by a CVD method, a PVD method, or a plating method. The structure of the laser-welded part (called the welded part) of the two metal plates consists of one metal plate (called the metal plate A) of the two metal plates and a carbon film laminated on the inner surface of the metal plate A (called the metal plate A). A carbon film (referred to as a carbon film on a metal plate A), a carbon film (referred to as a carbon film on a metal plate B) laminated on the inner surface of another metal plate (called a metal plate B) in contact with the carbon film on the metal plate A, and a metal. Claimed to be a plate B or a metal plate A, a carbon film on a metal plate A or a carbon film on a metal plate B, and a metal plate B, or a metal plate A and a metal plate B. Item 8. The method for producing a hydrogen gas conduit according to any one of Items 1 to 5. There are three laser welded parts (called welded parts) on the flat part of the metal plate on each side of the recess, and one of the structures of the three laser welded parts is one of the two metal plates. One metal plate (metal plate A), a carbon film laminated on the inner surface of the metal plate A (carbon film on the metal plate A), and another metal plate (metal plate) in contact with the carbon film on the metal plate A. B) A carbon film (carbon film on the metal plate B) and a metal plate B laminated on the inner surface.
The other one of the structures of the three laser welded parts is a metal plate A, a carbon film on the metal plate A or a carbon film on the metal plate B, and a metal plate B, and laser welding at the three places. The method for producing a hydrogen gas conduit according to any one of claims 1 to 6, wherein the remaining one of the structure of the portion is a metal plate A and a metal plate B. When two metal plates are combined and laser welded, a transparent jig presses a plurality of convex portions of the metal plate serving as a hydrogen conduit on the laser irradiation side, and the metal plate is welded through the transparent jig. The hydrogen gas conduit according to any one of claims 1 to 7, wherein a portion (referred to as a welded portion) is irradiated with a laser to melt-join two metal plates at the welded portion. Manufacturing method. The space including the area to be irradiated by the laser (referred to as welding space A) surrounded by the transparent jig, the convex portion of the metal plate, and the metal plate is filled with the shield gas. 8. The method for producing a hydrogen gas conduit according to any item of 8. When two metal plates are combined and laser welded, the parts to be welded (welded) of the metal plates by pressing the multiple convex parts of the metal plates that will be the hydrogen conduit on the side not irradiated with the laser with a holding jig or pedestal. The method for producing a hydrogen gas conduit according to any one of claims 1 to 9, wherein the two metal plates are weld-bonded at the site). The hydrogen gas conduit according to claim 10, wherein the holding jig or pedestal, the convex portion of the metal plate, and the space surrounded by the metal plate (referred to as welding space B) are filled with the shield gas. Manufacturing method. The hydrogen gas conduit according to any one of claims 9 to 11, wherein the pressure due to the shield gas in the welding space A and / or the welding space B is larger than the atmospheric pressure or the ambient pressure. Manufacturing method. The shield gas is claimed to be at least one gas selected from helium (He) gas, argon (Ar) gas, neon (Ne) gas, nitrogen (N ₂ ) gas, and carbon dioxide gas. The method for producing a hydrogen gas conduit according to any one of 9 to 12. The method for producing a hydrogen gas conduit according to any one of claims 1 to 13, wherein the carbon film on the outer surface of the metal plate to be irradiated with the laser is formed after laser welding. The method for producing a hydrogen gas conduit according to any one of claims 1 to 14, wherein the carbon film on the outer surface of the metal plate on the side not irradiated with the laser is formed after laser welding. The method for producing a hydrogen gas conduit according to any one of claims 1 to 15, wherein the metal plate is SUS304 or stainless steel or an iron-based material. The metal plate surface structure of a hydrogen conduit, which is a space for passing a gas containing hydrogen gas produced by welding two metal plates, is a structure in which a carbon film is laminated on the surface of the metal plate. conduit. The hydrogen conduit according to claim 17, wherein a carbon film is laminated on the surface of a metal plate inside the hydrogen conduit. The hydrogen conduit according to claim 17 or 18, wherein the structure is such that a carbon film is laminated on a metal plate surface outside the hydrogen conduit. The hydrogen conduit according to any one of claims 17 to 19, wherein the carbon film is a CVD carbon film, a PVD carbon film, or a plated carbon film. The hydrogen conduit according to any one of claims 17 to 20, wherein the metal plate is SUS304 or stainless steel or an iron-based material.