JP2011106023A - Porous metal laminated body and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated body in which a plurality of layers including porous metal layers are bonded to each other. <P>SOLUTION: A method for producing the porous metal laminated body 10 that is formed of the plurality of layers including the porous layer 11 in which a plurality of polyhedron-shaped voids of which the sides are composed of skeletons of metal-sintered bodies are formed in a mutually-continued state includes the steps of: laminating the porous layer 11 and an adjacent layer 12 made from metal; and fusing the porous layer 11 and the adjacent layer 12 in a laminated state into a desired shape with a laser. In the fusing step, a fusion-bonded layer 13 which bonds the porous layer 11 with the adjacent layer 12 is formed on the side faces of the porous layer 11 and the adjacent layer 12 by fusing and solidifying the porous layer 11 and the adjacent layer 12 with the laser. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a porous metal laminate and a method for producing the same.

  Conventionally, a porous metal laminate in which a plurality of layers of porous metal materials and the like are laminated on a filter, a secondary battery electrode, a solid polymer fuel cell current collector, a catalyst carrier, and the like has been used.

  For example, in Patent Documents 1 and 2, a laminate composed of two porous metal layers having different porosities is manufactured by degreasing and sintering in a state where two green layers containing metal powder are laminated. A method is disclosed. When each layer is the same kind of metal layer, the layers can be diffusion-bonded by double-coating and sintering the slurry.

  Patent Document 3 discloses a method of manufacturing a composite plate having a low contact resistance at a joint portion by brazing a porous metal layer and a metal plate.

  Patent Document 4 discloses a method for producing a porous metal laminate by stacking and sintering plate-like compacts containing metal powders and integrating them by diffusion bonding. According to this method, since a large number of laminates can be laminated and integrated, a laminate having a large thickness compared to the methods disclosed in Patent Documents 1 and 2 in which slurry is applied twice. Can be manufactured.

Japanese Patent No. 3508604 Japanese Patent No. 3982356 JP 2006-338903 A JP-A-9-87705

  However, in the methods disclosed in Patent Documents 1, 2, and 4, diffusion bonding is impossible because materials that are different in sintering conditions such as different metals cannot be sintered at the same time. Further, even if diffusion bonding is possible, the bonding surface is easily peeled off, and warpage due to a difference in thermal expansion may occur. Furthermore, when the formed bodies are diffusion bonded, there is a problem in that pores are distorted by applying pressure in the bonding direction, and discontinuity occurs in the porosity. In any case, when the shrinkage rate during sintering is different, such as the porosity of each layer is different, there is a risk of insufficient bonding strength, deformation, cracking, or the like.

  On the other hand, as disclosed in Patent Document 3, when a composite plate is manufactured by brazing, joining may be possible even if different metals are used. However, when joining the porous layers, the molten brazing material is absorbed by the voids in the porous layers, which may make joining difficult.

  This invention is made | formed in view of such a situation, and it aims at providing the laminated body by which the several layer containing a porous metal layer was mutually joined.

  The present invention relates to a method for producing a porous metal laminate comprising a plurality of layers including a porous layer in which a plurality of polyhedral voids each having a side constituted by a skeleton of a metal sintered body are formed in a continuous state. A laminating step of laminating the porous layer and an adjacent layer made of metal, and a fusing step of fusing the porous layer and the adjacent layer into a desired shape by laminating the porous layer and the adjacent layer. In the fusing step, the porous layer and the adjacent layer are bonded to the side surfaces of the porous layer and the adjacent layer by melting and solidifying the porous layer and the adjacent layer with the laser. A melt bonding layer is formed.

According to this manufacturing method, the porous layer and the adjacent layer can be joined simply by fusing the porous layer and the adjacent layer into a desired shape with a laser. For this reason, even if the porous layer and the adjacent layer are made of dissimilar metals that cannot be diffusion-bonded with each other, or are made of materials that have different shrinkage rates and are likely to be cracked or peeled off after joining, Any material that can be melted can be joined.
In addition, in the fusing step of this production method, a part of the melt-bonded layer enters into the voids of the porous layer and becomes an anchor, thereby producing a porous metal laminate in which the porous layer and the adjacent layer are reliably bonded. Is done.

  In the fusing step of this manufacturing method, it is preferable that the focal point of the laser is set on the joint surface between the porous layer and the adjacent layer. In this case, the amount of the liquid phase generated in the focal portion is larger than that of the other portions, and the temperature is high. When the assist gas flows here, the liquid phase appears, and at the same time, it is cooled, solidified and joined. At this time, since the liquid phase is solidified in an icicle shape, an anchor effect also appears.

  In this manufacturing method, the porous layer is preferably formed by forming a foamable slurry containing a metal powder and a foaming agent into a plate shape, foaming and then sintering. In this case, an arbitrary metal powder can be formed as a material for the porous layer, and the porosity, the ratio of the opening area, and the average opening diameter can be set to arbitrary sizes.

In this production method, the porous layer preferably has a porosity of 50% or more and 99% or less.
Moreover, it is preferable that the ratio of the opening area of the said space | gap in the front and back of the said porous layer is 15% or more and 85% or less.
Moreover, it is preferable that the said porous layer is 50 micrometers or more and 600 micrometers or less in the average opening diameter of the said space | gap in the said front and back.

  In these cases, a part of the melt-bonded layer easily enters the voids of the porous layer, and a porous metal laminate in which the adjacent layer and the porous layer are reliably bonded can be manufactured.

  The present invention also relates to a porous metal laminate comprising a plurality of layers including a porous layer in which a plurality of polyhedral voids each having a side constituted by a skeleton of a metal sintered body are formed in a continuous state. The porous layer, an adjacent layer made of metal and laminated on the porous layer, and provided along the porous layer and a side surface of the adjacent layer, and the porous layer and the adjacent layer are melted. And a melt bonding layer formed by solidification.

  In this porous metal laminate, since the porous layer and the adjacent layer are joined by the melt-bonded layer, the porous layer and the adjacent layer may be made of dissimilar metals that are difficult to diffuse and bond to each other. For example, it can be used in a wide range of applications as members constituting various devices such as electrodes, filters, catalyst carriers, and solid polymer fuel cell current collector plates that require a porous layer.

  In this porous metal laminate, it is preferable that a part of the fusion bonding layer enters the voids of the porous layer. In this case, a porous metal laminate is realized in which the melt-bonded layer enters the gap to become an anchor and each layer is securely bonded.

  According to the present invention, a laminate in which a plurality of layers including a porous metal layer are bonded to each other can be realized.

1 is a perspective view showing a porous metal laminate according to the present invention. It is sectional drawing which shows the porous metal laminated body which concerns on this invention. It is a side view which shows the manufacturing apparatus of a porous metal material.

  Hereinafter, embodiments of a porous metal laminate and a method for producing the same according to the present invention will be described. As shown in FIG. 1, the porous metal laminate 10 of the present embodiment includes a porous layer 11, an adjacent layer 12 made of metal and laminated on the porous layer 11, and the porous layer 11 and the adjacent layer 12. And a melt bonding layer 13 provided along the side surface. FIG. 2 is a partial cross-sectional view of the porous metal laminate 10.

As shown in FIG. 2, the porous layer 11 is a layer in which a plurality of polyhedral voids 11b each having a side constituted by a skeleton 11a of a sintered metal body are formed in a continuous state.
As shown in FIG. 2, in the present embodiment, the adjacent layer 12 has a plurality of polyhedral voids 12b each having a side formed by a skeleton 12a of a sintered metal body, as in the case of the porous layer 11. It is the layer currently formed in.
As shown in FIG. 2, the porous layer 11 and the adjacent layer 12 are laminated so that the bonding surface 11 c of the porous layer 11 and the bonding surface 12 c of the adjacent layer 12 are brought into contact with each other.

  As shown in FIG. 2, the melt bonding layer 13 is a layer formed by melting and solidifying the porous layer 11 and the adjacent layer 12. The melt bonding layer 13 is provided integrally with the porous layer 11 and the adjacent layer 12. And a part of this fusion bonding layer 13 enters into each space | gap of the porous layer 11 and the adjacent layer 12, and the porous layer 11 and the adjacent layer 12 are joined more firmly.

A method for manufacturing the porous metal laminate 10 will be described below.
[Lamination process]
First, the porous layer 11 and the adjacent layer 12 are laminated so that the bonding surfaces 11c and 12c come into contact with each other. At this time, if the porous layer 11 or the adjacent layer 12 is warped, the warp is corrected and flattened before being laminated, or the portions separated when the layers are laminated, an adhesive or an adhesive tape The gap between the joining surface 11c of the porous layer 11 and the joining surface 12c of the adjacent layer 12 is made small by temporarily securing with, for example, spot welding. Moreover, it may roll in the state which accumulated each layer, and may adhere | attach each layer.
[Fusing process]
Next, in a state where the porous layer 11 and the adjacent layer 12 are stacked, the laser beam is blown into a desired shape by a laser. The focal point of the laser is set on the joint surfaces 11 c and 12 c between the porous layer 11 and the adjacent layer 12. In this fusing process, the melted and solidified layer 13 that joins the porous layer 11 and the adjacent layer 12 to each other in the vicinity of the side surfaces of the porous layer 11 and the adjacent layer 12 becomes the porous metal laminate 10. It is formed along the side. At this time, since the porous layer 11 and the adjacent layer 12 are porous bodies provided with voids 11b and 12b and the thermal conductivity is low, only the surface layer portions on the side surfaces of the porous layer 11 and the adjacent layer 12 are melted, A melt bonding layer 13 is formed.

[Method for producing porous layer]
Here, an example of the manufacturing method of the metal porous material for forming the porous layer 11 is demonstrated. In addition, in this embodiment, since both the adjacent layer 12 and the porous layer 11 consist of the same metal porous material, it can manufacture with the following method. In this manufacturing method, a foamable slurry containing a metal powder and a foaming agent is formed into a plate shape (foamable slurry creation process and molding process), and foamed (foam drying process) and then sintered (sintering process). By doing so, the porous layer 11 and the adjacent layer 12 are formed.

<Foaming slurry preparation process>
First, a foamable slurry containing a metal powder and a foaming agent is prepared. The foamable slurry is prepared by mixing a metal powder forming a skeleton, a binder (water-soluble resin binder), a foaming agent and water, and, if necessary, a surfactant and / or a plasticizer. More specifically, a slurry containing a metal powder, a binder, and water is first prepared, and then a foaming agent is added to the slurry, followed by stirring with a stirring device such as a mixer.

  It does not specifically limit as metal powder, Ni, Cu, Ti, Al, Ag, stainless steel, etc. can be used. The metal powder preferably has an average particle size of 0.5 μm or more and 30 μm or less. Such a powder can be produced by an atomizing method such as a water atomizing method or a plasma atomizing method, a chemical process method such as an oxide reduction method, a wet reduction method, or a carbonyl reaction method.

  As the binder (water-soluble resin binder), methylcellulose, hydroxypropylmethylcellulose, hydroxyethylmethylcellulose, carboxymethylcellulose ammonium, ethylcellulose, polyvinyl alcohol, and the like can be used.

  The foaming agent is not particularly limited as long as it can generate gas and form bubbles in the slurry, and is a volatile organic solvent such as pentane, neopentane, hexane, isohexane, isopeptane, benzene, octane, toluene, etc. The water-insoluble hydrocarbon-based organic solvent can be used. The content of the foaming agent is preferably 0.1 to 5% by weight with respect to the foaming slurry.

  Surfactants include anionic surfactants such as alkylbenzene sulfonate, α-olefin sulfonate, alkyl sulfonate, alkyl ether sulfate, alkane sulfonate, polyethylene glycol derivatives, polyhydric alcohol derivatives, etc. Nonionic surfactants and amphoteric surfactants can be used.

  The plasticizer is added to impart plasticity to a molded product obtained by molding a slurry. For example, polyhydric alcohols such as ethylene glycol, polyethylene glycol, and glycerin, fats and oils such as coconut oil, rapeseed oil, and olive oil, petroleum ether, etc. Ethers such as diethyl phthalate, di-N-butyl phthalate, diethyl hexyl phthalate, dioctyl phthalate, sorbitan monooleate, sorbitan trioleate, sorbitan palmitate, sorbitan stearate, and the like can be used.

  Furthermore, an optional additive component may be added to improve the properties and moldability of the slurry. For example, a preservative can be added to improve the storage stability of the slurry, or a polymer compound can be added as a binding aid to improve the strength of the molded body.

  From the foamable slurry thus created, a molding process for forming a green sheet and a foam drying process are performed using the molding apparatus 20 shown in FIG.

<Molding process>
The forming apparatus 20 is an apparatus that forms a sheet-like formed body using a doctor blade method. The hopper 21 stores the foamable slurry, the carrier sheet 22 transports the foamable slurry S supplied from the hopper 21, A roller 23 that supports the carrier sheet 22, a blade (doctor blade) 24 that molds the foamable slurry S on the carrier sheet 22 to a predetermined thickness, a constant-temperature / high-humidity tank 25 that foams the foamable slurry S, and the foamed slurry Is provided with a drying tank 26 for drying. The lower surface of the carrier sheet 22 is supported by a support plate 27.

  In the molding apparatus 20, first, the foamable slurry S is put into the hopper 21, and the foamable slurry S is supplied onto the carrier sheet 22 from the hopper 21. The carrier sheet 22 is supported by a roller 23 and a support plate 27 that rotate in the right direction in FIG. 3, and its upper surface moves in the right direction in the figure. The foamable slurry S supplied onto the carrier sheet 22 is formed into a thin plate shape by the blade 24 while moving together with the carrier sheet 22.

<Foam drying process>
Next, the thin plate-like foamable slurry S moves in the constant temperature / high humidity tank 25 under predetermined conditions (for example, temperature 30 ° C. to 40 ° C., humidity 75% to 95%) over 10 minutes to 20 minutes, for example. Foam. Subsequently, the slurry foamed in the constant temperature / high humidity tank 25 moves in the drying tank 26 under a predetermined condition (for example, a temperature of 50 ° C. to 70 ° C.) over 10 minutes to 20 minutes, for example, and is dried. Thereby, a sponge-like green sheet (not shown) is obtained.

<Sintering process>
The thin sheet metal porous material is formed by degreasing and sintering the green sheet thus obtained. Specifically, for example, after removing (degreasing) the binder (water-soluble resin binder) in the green sheet under vacuum at temperatures of 550 ° C. to 650 ° C. for 25 minutes to 35 minutes, the temperature is further increased in vacuum. Sintering is performed at 700 ° C to 1300 ° C for 60 minutes to 120 minutes. By this metal porous material, the porous layer 11 and the adjacent layer 12 which comprise the porous metal laminated body 10 of this invention can be manufactured.

  According to the method for manufacturing the porous layer 11 and the adjacent layer 12 described above, the porosity, opening ratio, average opening diameter, etc. of the porous layer 11 can be arbitrarily set within a predetermined range.

<Porosity>
The volume ratio of the voids in the metal porous material is called the void ratio. The porosity can be calculated from the actually measured weight with respect to the weight of the solid body of the same shape.
In the porous metal laminate 10 according to the present invention, the porosity of the porous layer 11 is preferably set to 50% or more and 99% or less.

<Aperture ratio>
The ratio of the opening area of the opening part of the space | gap in the front and back of a metal porous body is called opening ratio. The aperture ratio is determined by measuring the visual field area A and the total area Ap of all the openings on the outermost surface in the visual field using a 25-300 magnification micrograph of the surface of the metal porous body. Calculated by the formula.
Opening ratio (%) = Ap / A × 100
In the porous metal laminate 10 according to the present invention, it is desirable to set the ratio of the opening areas of the voids 11b and 12b on the front and back surfaces of the porous layer 11 to 15% or more and 85% or less.

<Average opening diameter>
The average opening size of the voids on the front and back surfaces of the metal porous material can be represented by a diameter when each opening is regarded as a circle, and this is hereinafter referred to as an average opening diameter. The average aperture diameter is an arithmetic average of the equivalent circle diameters calculated by measuring the area of each aperture on the outermost surface in the field of view in a 25 to 300-fold photomicrograph.
In the porous metal laminate 10 according to the present invention, it is desirable to set the average opening diameter of the porous layer 11 to 50 μm or more and 600 μm or less.

Next, a specific example is described about the manufacturing method of the porous metal laminated body 10 of this embodiment.
[Example 1]
First, the porous layer 11 and the adjacent layer 12 shown in Table 1 were formed by the method for producing a metal porous material described above.

  Next, the porous layer 11 and the adjacent layer 12 were laminated. At this time, the warpage of each layer was corrected and temporarily retained so that the gap between the porous layer 11 and the adjacent layer 12 was within 0.1 mm. Warpage can be corrected by a mechanical method using a press or a straightening machine.

  The laminated porous layer 11 and adjacent layer 12 were melted into a 10 mm × 30 mm square under the conditions shown in Table 2, and the side surfaces of the porous layer 11 and the adjacent layer 12 were melted and solidified. Thereby, the integral fusion | bonding layer 13 in which each layer mixed was formed in the vicinity of the joint surfaces 11c and 12c, and the porous layer 11 and the adjacent layer 12 were joined.

  In this example, compared to the general conditions of fusing by laser, the laser frequency was increased to lower the energy per pulse, while continuously firing, and the processing speed was increased, which is necessary. The above heat input was controlled. Further, by setting the focal point of the laser to the bonding surfaces 11c and 12c, the liquid phase amount at the bonding portion was increased and the temperature was increased. Generally, cutting is performed by causing a sufficient liquid phase to appear and blowing it away. On the other hand, by controlling so that the appearing liquid phase remains in the joint portion, icicle-shaped burrs (drosses) generally hated in the cutting process are used for anchor formation.

  FIG. 2 shows a cross section of the porous metal laminate 10 manufactured as described above in the vicinity of the joining surfaces 11c and 12c of the porous layer 11 and the adjacent layer 12. The liquid phase that has appeared as a result of melting of the porous layer 11 and the adjacent layer 12 scatters in the gaps 11a and 12a, and as shown by reference numeral 14 in FIG. The These portions function as anchor portions and strengthen the bonding between the porous layer 11 and the adjacent layer 12.

[Example 2]
Next, the joining of the porous layer manufactured by the above-described metal porous material manufacturing method and the adjacent layer made of a solid solid material (plate material) will be described. Table 3 shows the materials and shapes of the porous layer and the adjacent layer.

  Next, these porous layers and adjacent layers were laminated. At this time, the warpage of each layer was corrected so that the gap between the porous layer and the adjacent layer was within 0.1 mm, and the layer was temporarily retained by spot welding. Warpage can be corrected by a mechanical method using a press or a straightening machine.

  The laminated porous layer and the adjacent layer were melted into a 10 mm × 30 mm square under the conditions shown in Table 4, and the sides of the porous layer and the adjacent layer were melted and solidified. As a result, an integral fusion bonding layer in which the layers were mixed in the vicinity of the bonding surface was formed, and the porous layer and the adjacent layer were bonded. The laser at the time of fusing was irradiated from the porous layer side toward the adjacent layer side. Thereby, it became possible to process while maintaining the foam shape. On the contrary, when the irradiation is performed from the adjacent layer side toward the porous layer side, the amount of the liquid phase that appears is excessive, and the foam is sealed or melted. It becomes difficult.

  In this embodiment, compared with the first embodiment, the liquid phase is increased by increasing the laser output, and the energy per pulse is increased by lowering the frequency. In addition, the fusion bonding layer is increased by reducing the laser processing speed as compared with the first embodiment. Further, the pressure of the assist gas is set small so as not to blow off the liquid phase. By fusing under such conditions, the portion of the joint form at the joint interface occupied by the metallurgical joint from the mechanical joint such as the anchor increases, and as a result, the joint strength increases.

  As described above, according to the present invention, even if a material that is difficult to diffusely bond between different metals, or a material that has a different shrinkage due to a difference in thickness, pore diameter, porosity, etc. A porous metal laminate using various materials can be obtained by simply performing laser fusing in a state where the porous layer and the adjacent layer are laminated.

  That is, in the porous metal laminate of the present invention, the adjacent layer may be a material melted by a laser, and may be a porous material or a solid solid material. For example, when the adjacent layer is a solid solid material, the strength can be improved, so that a porous metal laminate that can be suitably used for a filter or a secondary battery electrode can be realized.

In addition, this invention is not limited to the thing of the structure of the said embodiment, In a detailed structure, it is possible to add a various change in the range which does not deviate from the meaning of this invention. For example,
By laminating a large number of layers, a thick porous metal laminate suitable for electrodes, filters, catalyst carriers and the like can be produced. Furthermore, by using a porous layer and an adjacent layer made of porous bodies each having different void sizes and void ratios, the voids are continuous in the thickness direction and the void sizes and void ratios in the thickness direction. However, for example, a porous metal laminate suitable for a current collector plate of a polymer electrolyte fuel cell can be produced.

DESCRIPTION OF SYMBOLS 10 Porous metal laminated body 11 Porous layer 11a frame | skeleton 11b space | gap 11c joining surface 12 adjacent layer 12a frame | skeleton 12b space | gap 12c joining surface 13 fusion | bonding layer 14 anchor part 20 shaping | molding apparatus 21 hopper 22 carrier sheet 23 roller 24 blade (doctor blade)
25 Constant temperature / high humidity tank 26 Drying tank 27 Support plate S Effervescent slurry

Claims (10)

A method for producing a porous metal laminate comprising a plurality of layers including a porous layer in which a plurality of polyhedral voids whose sides are constituted by a skeleton of a metal sintered body is formed in a continuous state,
A laminating step of laminating the porous layer and an adjacent layer made of metal;
A fusing step of fusing the porous layer and the adjacent layer into a desired shape with a laser in a laminated state,
In the fusing step, the porous layer and the adjacent layer are melted and solidified by the laser so that the porous layer and the adjacent layer are joined to the side surfaces of the porous layer and the adjacent layer. A method for producing a porous metal laminate, comprising forming a layer.   2. The method for producing a porous metal laminate according to claim 1, wherein, in the fusing step, the focal point of the laser is set at a joint surface between the porous layer and the adjacent layer.   The porous layer according to claim 1 or 2, wherein the porous layer is formed by forming a foamable slurry containing a metal powder and a foaming agent into a plate shape, foaming and then sintering. A method for producing a metal laminate.   The method for producing a porous metal laminate according to any one of claims 1 to 3, wherein the porous layer has a porosity of 50% or more and 99% or less.   The method for producing a porous metal laminate according to any one of claims 1 to 4, wherein the porous layer has an opening area ratio of 15% to 85% on the front and back surfaces thereof.   6. The method for producing a porous metal laminate according to claim 1, wherein the porous layer has an average opening diameter of 50 μm or more and 600 μm or less on the front and back surfaces.   The method for producing a porous metal laminate according to any one of claims 1 to 6, wherein the adjacent layer is a solid solid material. A porous metal laminate comprising a plurality of layers including a porous layer in which a plurality of polyhedral voids whose sides are constituted by a skeleton of a metal sintered body is formed in a continuous state,
The porous layer;
An adjacent layer made of metal and laminated on the porous layer;
A porous metal laminate, comprising: a melt bonding layer provided along side surfaces of the porous layer and the adjacent layer, wherein the porous layer and the adjacent layer are melted and solidified.   9. The porous metal laminate according to claim 8, wherein a part of the fusion bonding layer enters the void of the porous layer.   The porous metal laminate according to claim 8 or 9, wherein the adjacent layer is a solid solid material.

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