JP2019090065A - Aluminum porous member and method for producing the same - Google Patents

Abstract

To provide an aluminum-based porous member which is braze-joined to an applied member in a simplified manner.SOLUTION: The aluminum-based porous member has an aluminum-based porous body composed of aluminum or an aluminum alloy, and a porous lamellar body which is integrally formed along the outer periphery of the aluminum-based porous body, wherein the porous lamellar body has the same composition as that of the aluminum-based porous body and has a fine pore diameter smaller than the aluminum-based porous body. A method for producing the aluminum-based porous member includes the steps of: preparing a precursor having a porous resin substrate, a lamellar porous resin which has a fine pore diameter smaller than the porous resin substrate and is adjacent to the porous resin substrate, and aluminum powder attached to the surfaces of the porous resin substrate and the lamellar porous resin; and heating the precursor, thermally decomposing the porous resin substrate and the lamellar porous resin, thereby melting the aluminum powder to produce the aluminum-based porous boy and the porous lamellar body.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an aluminum-based porous member mainly composed of an aluminum-based porous body having a three-dimensional network structure and easy in work and handling for joining to an application member, and a method of manufacturing the same.

  Conventionally, an aluminum heat exchanger is mounted on a vehicle and used as an evaporator, a condenser or the like. In the heat exchanger, in order to promote heat conduction between the fluid and the heat exchanger, fins made of aluminum or the like are provided in the flow path through which the fluid flows. When joining such an aluminum member to an aluminum heat exchanger, brazing is used, and a liquid or paste brazing composition is used.

  The heat transfer efficiency of the member promoting heat transfer such as a fin changes depending on its structure, so improvements are made to variously refine the structure of the fin in order to increase the contact area and enhance the heat transfer efficiency. There is.

  On the other hand, a method for producing a metal porous body having a three-dimensional network structure has recently been proposed, and it has become possible to provide a metal porous body. In the following Patent Documents 1, 2 and 4, it is described that a slurry in which a metal powder is dispersed is attached to a resin porous body, and the resin is decomposed by heating to disappear and thereby obtain a metal porous body. Further, in Patent Document 5 below, a pressure-sensitive adhesive is attached to the surface of a skeleton of a three-dimensional network structure to be a substrate, and then a powder is attached and heat-treated to form a three-dimensional network structure made of metal or ceramic. It is stated that the body is obtained. On the other hand, Patent Document 6 below describes a method for producing a porous iron body, and according to the technique of this document, surface oxidized iron powder is mixed with a binder and applied to the skeleton of porous polymer resin This is heated to carry out the disappearance of the polymer resin and the sinter reduction of the iron powder to obtain an iron porous body. Also, a method for producing a porous metal body has been proposed which utilizes electrodeposition of metal on the surface of a foamed resin skeleton by electroplating (Patent Documents 3 and 7 below).

  In such circumstances, limitations have been seen in attempts to improve the heat transfer efficiency by structural changes in the fins that promote heat transfer, and different forms of members in place of the fins are sought. In this regard, the metal porous body is considered to be preferable as a heat exchange material because the metal porous body has a high thermal conductivity and a large surface area (Patent Document 7 below).

  Because of this, in recent years, the present inventors have also developed aluminum-based porous bodies, thinking that they are promising as members used to promote heat conduction instead of fins etc., and are porous for heat exchangers. The examination as a member is conducted (the following patent document 8).

Japanese Patent Application Laid-Open No. 05-339605 Patent Document 1: Japanese Patent Application Publication No. 08-020831 JP-A-57-174484 Japanese Patent Publication No. 61-053417 JP 06-235033 A Japanese Examined Patent Publication No. 06-089376 JP, 2011-236477, A JP, 2016-142420, A

  However, conventional brazing techniques for aluminum-based members have many problems such as storage stability and safety of the brazing composition, and basically, the brazing operation tends to be complicated. Moreover, in a product such as a heat exchanger, a portion to be brazed includes a tube material forming a heat exchange flow passage, a joint portion of a fin material to radiate heat, and the like. The brazing material erosion (erosion) due to excessive heating is very likely to cause defects such as perforation. Erosion is a phenomenon that has become a serious technical problem in joining of aluminum-based members, which has recently been reduced in weight, and includes erosion due to diffusion of the brazing material component (silicon) and erosion due to flowing brazing material.

  In addition, since the porous aluminum body developed in recent years also has a fine structure, the technical difficulty of brazing is higher than that of a general-purpose plate fin material. Furthermore, in consideration of the prevention of damage etc. in handling, handling at the time of brazing is difficult. From such a thing, in order to use an aluminum porous body as a member for promoting heat conduction in a heat exchanger etc. instead of the conventional fin, the improvement which becomes easy [joining] is needed.

  An object of the present invention is to solve the above-mentioned problems and to provide an aluminum-based porous member which can be easily brazed to various aluminum products including aluminum heat exchangers and the like, and a method for producing the same.

  As a result of various investigations on each material constituting the brazing composition and the form of the material, the present inventors added an aluminum-based layered body having a simple brazing operation to the aluminum-based porous body. It reached.

  According to one aspect of the present invention, the aluminum-based porous member is formed of an aluminum-based porous body made of aluminum or an aluminum alloy, and a porous layered body integrally formed along the outer periphery of the aluminum-based porous body. And the porous layered body has the same composition as the aluminum-based porous body and has a smaller pore diameter than the aluminum-based porous body.

  When the porous layered body has a flat shape having an average pore diameter of 1000 μm or less and an average thickness of 10 μm or more and 1 mm or less, it is very easy to join by brazing. The shape of the aluminum-based porous body is highly versatile if it is a rectangular solid. Furthermore, an aluminum-based porous member can be configured to have an aluminum-based thin film formed on the outer peripheral surface of the porous layered body on the opposite side to the aluminum-based porous body, and the aluminum-based thin film It has the same composition as the aluminum-based porous body. When the porosity of the aluminum-based porous body is 92 to 99%, the porous layered body functions as a good heat conducting member by being joined to the heat exchanger.

  Further, according to one aspect of the present invention, a method for producing an aluminum-based porous member comprises: a porous resin substrate; and a layered pore having a smaller pore diameter than the porous resin substrate and being adjacent to the porous resin substrate. Preparing a precursor having a porous resin, the porous resin substrate, and an aluminum-based powder adhering to the surface of the layered porous resin, and heating the precursor to form the porous resin substrate and the porous resin substrate A heating step of thermally decomposing the layered porous resin and melting the aluminum-based powder to form an aluminum-based porous body and a porous layered body, an aluminum-based porous body and a porous layered formed by the heating step The gist of the present invention is that the method comprises the steps of cooling the body and integrally forming the porous layered body and the aluminum-based porous body.

  The preparation step includes a preparation step of preparing an aluminum-based powder dispersion in which the aluminum-based powder is dispersed in a dispersion medium, an adhesion step of adhering the porous resin substrate to the layered porous resin, and adhesion in the adhesion step. Applying the aluminum-based powder dispersion on the surface of the porous resin substrate and the layered porous resin, and the porous resin substrate and the layered porous resin coated with the aluminum-based powder dispersion And drying to obtain the precursor by removing the dispersion medium. Alternatively, the preparation step is a preparation step of preparing an aluminum-based powder dispersion in which the aluminum-based powder is dispersed in a dispersion medium, and a first coating step of applying the aluminum-based powder dispersion on the surface of the porous resin substrate. And a second application step of applying the aluminum-based powder dispersion to the layered porous resin, and the porous resin substrate to which the aluminum-based powder dispersion has been applied, the aluminum-based powder dispersion being applied. The method may be carried out so as to obtain the precursor by placing on the layered porous resin and drying the porous resin base and the layered porous resin to remove the dispersion medium.

  In the coating step or the second coating step, it is preferable that the layered porous resin be coated with the aluminum-based powder dispersion so that the aluminum-based powder dispersion is excessively contained in pores. The aluminum-based powder dispersion preferably has a viscosity of 20 to 1000 mPa · s (rotational speed: 50 rpm) at 25 ° C., and the layered porous resin preferably has a cell number of 30 to 60 ppi. The aluminum-based powder is an aluminum powder or an aluminum alloy powder, and when the average particle diameter is 1 μm or more and 50 μm or less, adhesion to the porous resin surface is good.

  According to the present invention, an aluminum-based porous member in which the layered body is integrated with the aluminum-based porous body is provided, the handling of the aluminum-based porous body is facilitated, and the breakage during handling is reduced. The porous body can be joined by a simple operation. When joining an aluminum-type porous body to the board | plate material which comprises a heat exchanger, a pipe material, etc., it is possible to perform brazing joining simply.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic diagram which shows one Embodiment of the aluminum-type porous member which concerns on this invention. The schematic diagram which shows the modification of the aluminum-type porous member which concerns on this invention.

  The paste-like brazing composition is a useful bonding material that can place a brazing material at any location to form a bond. However, in the manufacture of heat exchangers, there is a process in which flat tubes and fin materials are incorporated in multiple layers in multiple stages, and the burden due to the repetition of the process of applying the brazing material and labor and time are problems in mass production It becomes. Moreover, control of the thickness of a coating film is also very difficult.

  The present inventors are examining various applications, such as application to a heat exchanger, regarding the aluminum-based porous body which has already been proposed (see the above-mentioned Patent Document 8). However, brazing of an aluminum-based porous body is more technically difficult than general-purpose plate fin materials. One of the causes is that, since the aluminum-based porous body is a network structure formed of a fine skeleton having a diameter of about 100 μm, basically, it is likely to cause a change due to the erosion of silicon in the brazing material. It is easy to cause melting deformation and disappearance. In other words, structural failure is likely to occur at the time of brazing. Also, because of the fragile microstructure, defects during handling also increase bonding failure. In particular, when the skeleton itself forming the porous body is hollow, although it is advantageous in weight reduction, the erosion of silicon becomes stronger, and the strength needs to be considered also in handling.

  Because of this, in order to join an aluminum-based porous body instead of a fin material to a heat transfer surface such as a heat exchanger or a heat source, a homogeneous and dense layered body is added to the aluminum-based porous body An aluminum-based porous member having a structure is useful. Since the ends of the three-dimensional network-like framework constituting the aluminum-based porous body are substantially point-like, the brazing joint at the framework ends has a low probability, and this point is the composition for brazing to the joining surface The same is true when the object is applied or when applied to the end of the skeleton. On the other hand, in the case of an aluminum-based porous member in which the layered body is attached to the aluminum-based porous body, the layered body may be joined to the surface to be joined. Increased accuracy. Also, the application of the brazing composition and the flux is an easy operation on the layered body. Furthermore, since brazing and bonding progress on the surface of the layered body, it is possible to suppress the melt failure due to the erosion of the framework end of the aluminum-based porous body. Also, since it has a simple structure, there is no substantial difference from the case of incorporating an aluminum-based porous body alone even in the state of being incorporated in a heat exchanger etc., and the thermal conductivity is lowered, the flow resistance of fluid There is no increase in In addition, during handling, breakage of the skeleton constituting the aluminum-based porous body is also less likely to occur. Below, an aluminum-type porous member is demonstrated in detail. In addition, the term "aluminum-based" in the description means a metal in the range belonging to "aluminum and aluminum alloy".

  A layered body is a planar flat element, and is a member joined to a to-be-joined surface, such as a heat exchanger. For the purpose of facilitating brazing, the material of the layered body may not necessarily be a non-porous material such as a molten material. That is, if the porous body is dense, its surface can be handled similarly to a multi-hole plate having a large number of openings, and substantially the same surface and surface as bonding of the surface and the surface in the molten material. Bonding with is possible. Therefore, in the present invention, the layered body is configured as a dense porous body in which the outer peripheral surface can be treated substantially as a surface. Such a porous layered body can be formed together with the aluminum based porous body using a layered porous resin in the manufacturing process of forming the skeleton of the aluminum based porous body. Thus, an aluminum-based porous member in which the layered body is integrally formed along the outer periphery of the aluminum-based porous body is obtained.

  As one embodiment of the aluminum-based porous member, an aluminum-based porous member 1 as shown in FIG. 1 can be mentioned. In the aluminum-based porous member 1, the porous layered body 3 is integrally formed on one outer peripheral surface (lower surface) of the rectangular parallelepiped aluminum-based porous body 2. An aluminum porous member configured using a flat rectangular parallelepiped aluminum-based porous body is advantageous in terms of versatility. Since the porous layered body 3 of the aluminum-based porous member 1 is an aluminum-based dense layer, the outer peripheral surface thereof approximates a flat material having a large number of small openings. Therefore, it is easy to apply the brazing composition to the porous layered body, and when it is brought into close contact with the workpiece and heated to the brazing temperature, a bond is easily formed with the workpiece. Therefore, for example, the aluminum-based porous body is joined via the porous layered body by disposing the member in the flat tube constituting the main portion of the heat exchanger and brazing and joining the members, and the joining is performed via the joining. Good heat transfer is possible.

  The thickness of the porous layered body integrated with the aluminum-based porous body can be appropriately set as required. It is preferable that the thickness of the porous layered body is about 1/10 or less of the thickness of the aluminum-based porous body, in order to avoid an increase in air flow resistance when used as a heat exchange fin. However, if the porous layered body is excessively thin, it is likely to be damaged or deformed during handling, and if it is too thick, it may become a design obstacle or the like. Therefore, taking these into consideration, the thickness of the porous layered body is about 2 mm or less, preferably about 10 μm or more and about 1 mm or less, so that the aluminum-based porous body functions well after brazing. It is preferable to set the average thickness to about 100 μm or more and about 500 μm or less.

  The porous layered body is made of aluminum or an aluminum alloy. The porous layered body can be formed using an aluminum-based powder which is a raw material of the aluminum-based porous body, whereby the porous layered body has substantially the same composition as the aluminum-based porous body. A layered body made of aluminum is preferred in view of high thermal conductivity. With respect to the aluminum alloy, a composition in a range in which the thermal conductivity is good can be appropriately selected.

  When the porous layered body is made of aluminum, a brazing composition generally used for joining aluminum is applied to the porous layered body, and the aluminum-based porous member is assembled on the surface to be joined and heated. Thereby, a brazed joint is formed. The brazing composition is a paste-like or flowable composition containing a brazing material powder and a flux.

  The porous layered body as described above can be integrally formed with the aluminum-based porous body in the process of manufacturing the aluminum-based porous body. That is, with the completion of the aluminum-based porous body, an aluminum-based porous member in which the porous layered body is integrally formed can be obtained. Since the porous layered body is continuous with the skeleton of the aluminum based porous body, and the aluminum based porous body is supported by the dense porous layered body, the resulting aluminum based porous member becomes easy to handle. It is possible to reduce the breakage of the skeleton that constitutes the aluminum-based porous body during transportation, and the loss of the skeleton and the powdering are reduced.

  Below, the manufacturing method of an aluminum-type porous member is demonstrated in detail. According to the manufacturing method described below, the aluminum-type porous member can obtain the thing of the preferable characteristic excellent as for heat conduction promotion. In order to form a porous layered body with an aluminum-based porous body, a porous resin with fine eyes (that is, small pore size) is used. Since the porous resin with fine eyes tends to hold the liquid in the communication holes, the skeleton of the porous layered body formed from the powder is thick, and a layered body with small porosity can be formed.

(Aluminum-based porous body manufactured)
The aluminum-based porous body is a porous body in which pores (communication holes) communicating in three dimensions are formed by a skeleton of a three-dimensional network structure made of aluminum or aluminum alloy. Integration with the layered body and brazing to the surface to be joined are carried out by selecting any aluminum-based porous body depending on the application. Therefore, the porosity of the aluminum-based porous body is not particularly limited, and a porous body having an appropriate porosity and pore size may be produced as needed, and generally, the porosity is about 80 to 99%, fine. It is useful to produce an aluminum porous body having a pore diameter of about 30 to 4000 μm. When used as a fin material of a heat exchanger, the porosity (proportion of the volume of pores (voids) per unit volume of porous body) is about 92 to 99% from the viewpoint of contact efficiency with fluid, air flow resistance, etc. The porous body is preferable, and more preferably, a porous body having a porosity of about 95 to 97% may be used. Moreover, it is preferable that the thickness of a frame | skeleton is about 50-500 micrometers. The porosity can be calculated from the density of the aluminum-based porous body and the density of aluminum (or aluminum alloy) (true density, aluminum: 2.7 g / cm ³ ), and the density of the porous body Is obtained by measuring the volume and mass of the porous body.

(Production of aluminum-based porous material)
The aluminum-based porous body as described above can be manufactured using an aluminum-based powder (aluminum powder or aluminum alloy powder). Specifically, an aluminum-based powder is attached to the surface of a porous resin base (foamed resin) having communicating holes, and the porous resin is decomposed and burned off by heating. At the time of heating, most components except the aluminum-based powder are thermally decomposed and disappear, and only trace amounts of carbon and silicon remain. By heating above the melting point of aluminum (or aluminum alloy), the inside of the particles of the aluminum-based powder is melted, but the oxide film, trace components, etc. present in the surface layer of the particles have a three-dimensional structure formed by the powder particles. maintain. The molten aluminum (or aluminum alloy) expands to break the oxide film, and spreads on the surface layer of the particle to react. As a result, the aluminum-based powder particles are fused and continue to form a skeleton of an aluminum (or aluminum alloy) porous body. By cooling this, aluminum (or aluminum alloy) solidifies while maintaining the three-dimensional structure, and an aluminum-based porous body is formed. This is a unique method by means of aluminum and aluminum alloy powders forming oxide films, which can not be achieved, for example, with copper powder. In the process of producing such an aluminum-based porous body, if the heating step is carried out in a state where the porous resin substrate to which the aluminum-based powder is attached and the layered body are in contact, the layered body and the aluminum-based porous body Integral formation is achieved. That is, while the fusion of the aluminum-based powder proceeds by heating, the fusion of the powder and the layered body also proceeds. Therefore, if the layered porous resin to which the aluminum-based powder is attached is present at the time of heating, and the porous resin substrate to which the aluminum-based powder is attached is in contact with this, burnout of the layered porous resin and aluminum-based By melting the powder, an aluminum-based layered body is formed and integrated with the adjacently produced aluminum-based porous body. Therefore, the aluminum-based porous member in which the aluminum-based porous body and the porous layered body are integrally formed is obtained.

  In order to carry out such a heating step, a precursor having a porous resin substrate, a layered porous resin in contact with the porous resin substrate, and an aluminum-based powder attached to the surface of the porous resin substrate and the layered porous resin You should prepare your body and use it. The precursor is heated to thermally decompose the porous resin substrate and the layered porous resin, and the aluminum-based powder is melted, whereby the skeleton of the aluminum-based porous body corresponding to the porous resin substrate and the layered porous resin And a skeleton of the porous layered body corresponding to The skeleton of the resulting aluminum-based porous body and the skeleton of the porous layered body are solidified in the cooling step to integrally form the porous layered body and the aluminum-based porous body.

  As a method of adhering the aluminum-based powder to the surface of the porous resin, electroplating, a dry method, a wet method, etc. may be mentioned, and in any method, the porous resin or resin to which the aluminum-based powder is adhered. Although a sheet can be obtained, a wet method is preferable in terms of simplicity and ease of control. In the wet method, a slurry-like dispersion liquid in which an aluminum-based powder is dispersed in a dispersion medium is prepared, and the porous resin is impregnated with the dispersion liquid by, for example, immersing the porous resin in the dispersion liquid. Take out, remove the excess dispersion from the porous resin and dry. Thereby, porous resin which aluminum system powder adhered to the surface can be obtained simply.

  The wet method has an advantage that the amount of the aluminum-based powder to be attached to the porous resin can be adjusted by adjusting the viscosity of the aluminum-based powder dispersion to be used. Furthermore, since the aluminum-based powder easily wets and spreads with the flow of the dispersion medium, the wet method is also excellent in that powder particles are sufficiently attached to the porous resin surface to coat the surface.

When preparing the above-mentioned precursor on the premise of performing adhesion of aluminum system powder by a wet method, the following forms can be mentioned concretely as a preparatory process.
As a first embodiment, a preparation step of preparing an aluminum-based powder dispersion in which an aluminum-based powder is dispersed in a dispersion medium, a bonding step of bonding a porous resin substrate to a layered porous resin, a bonded porous resin substrate and A coating step of coating the surface of the layered porous resin with an aluminum-based powder dispersion, and a drying step of drying the porous resin substrate coated with the aluminum-based powder dispersion and the layered porous resin to remove the dispersion medium Sequentially, this gives a precursor. The step of applying the aluminum-based powder dispersion to the surfaces of the porous resin substrate and the layered porous resin is achieved by immersing the porous resin substrate and the layered porous resin in the aluminum-based powder dispersion and then taking it out. The application amount of the aluminum-based powder dispersion can be adjusted by appropriately squeezing the porous resin substrate and the layered porous resin after immersion.

  As a second embodiment, a preparation step of preparing an aluminum-based powder dispersion in which an aluminum-based powder is dispersed in a dispersion medium, a first coating step of applying an aluminum-based powder dispersion on the surface of a porous resin substrate, layered porous The second application step of applying an aluminum-based powder dispersion to the surface of the resin, and the porous resin substrate to which the aluminum-based powder dispersion is applied is placed on the layered porous resin to which the aluminum-based powder dispersion is applied. And drying the porous resin substrate and the layered porous resin to remove the dispersion medium, whereby a precursor is obtained. Since the coating step is individually performed on each of the porous resin substrate and the layered porous resin, adjustment and change of the coating amount in each are easy. That is, the amount of the aluminum-based powder contained in the layered porous resin can be changed as needed. In addition, since the fine layered porous resin is excellent in the internal retention ability of the aluminum-based powder dispersion, it is possible to precisely form the porous layered body by suppressing the flow of the aluminum-based powder dispersion before drying. it can.

  A fine-grained (small pore diameter) layered porous resin has a relatively high ability to retain an aluminum-based powder dispersion. Therefore, when the porous resin substrate or the layered porous resin contains an excess of the aluminum-based powder dispersion, the excess dispersion tends to be stored in the pores of the layered porous resin, particularly in the pores near the lowermost part thereof. is there. Therefore, in the precursor after drying, the aluminum-based powder is deposited in the pores of the layered porous resin, and in the porous layered body formed through the heating step, the lower pores are narrowed and the lower part is narrowed. The openings of the pores in the outer peripheral surface (bottom surface) are reduced. When the aluminum-based powder deposited in the pores of the layered porous resin further increases, the lower outer peripheral surface of the porous layered body 3 to be formed (aluminum-based porous member 1 'shown in FIG. 2) The openings of the pores in the opposite side of the porous body are substantially eliminated, and an aluminum-based thin film (thin film 4) is formed at the bottom of the porous layered body 3, and the thin film 4 is substantially made of a molten material. It becomes equally impermeable. That is, depending on the amount of deposited powder in the pores, the thin film 4 is formed to be multi-hole or non-permeable. The presence of such a thin film is further advantageous in the ease of operation and the ease of handling in brazing. The application amount of the aluminum-based powder dispersion and the excess amount contained in the resin can be adjusted by the degree of squeezing of the porous resin after being immersed in the aluminum-based powder dispersion. Therefore, the setting of the squeezing conditions can control the formation of the aluminum-based thin film.

(Method of manufacturing aluminum-based porous member)
The details of the production method for producing the aluminum-based porous member through the preparation of the precursor as described above will be described below.

  In adhesion of the aluminum-based powder by a wet method, a slurry-like dispersion liquid in which the aluminum-based powder is dispersed in a dispersion medium is prepared and used. As the dispersion medium, volatile solvents such as alcohols and water can be suitably used, and by dissolving the binder in the dispersion medium, the adhesion of the aluminum-based powder particles can be enhanced. In addition, by incorporating a dispersing agent into the dispersion medium, it is possible to suppress the sedimentation of the aluminum-based powder particles and stabilize the dispersed state of the particles. In the wet method, the amount of the aluminum-based powder adhering to the surface of the porous resin can be adjusted by adjusting the viscosity of the aluminum-based powder dispersion. This point will be described later.

(Aluminum-based powder used)
The aluminum-based powder is a powder that forms a skeleton and a layered body of the aluminum-based porous body, so its composition is required for the thermal conductivity, specific gravity and strength (hardness, brittleness, ductility) required of the aluminum-based porous body It is selected from pure aluminum and aluminum alloy in consideration of etc. Specifically, in addition to pure aluminum powder having a purity of 99.5% by mass or more, an aluminum alloy powder in which a component for improving the mechanical strength and corrosion resistance of aluminum and a component for lowering the sintering temperature to a low temperature are alloyed in advance. It can be used. As such an alloying component, copper, manganese, zinc, silicon, calcium, magnesium etc. can be illustrated, for example. However, it is desirable to set the content of magnesium, which is a factor that inhibits sintering and brazing, to 0.5 mass% or less. Aluminum alloys pre-alloyed by blending alloying components such as copper, manganese, magnesium and silicon are useful for improving the strength of the resulting aluminum-based porous body, while their thermal conductivity is higher than that of aluminum Also falls. Therefore, it is preferable to adjust the content of the alloying component so as to obtain desired physical properties. From such a viewpoint, the total content of elements other than aluminum is preferably 10% by mass or less, and more preferably 5% or less. By setting the content above, excellent heat transfer performance and mechanical strength can be maintained. The aluminum-based powder may be appropriately selected from commercially available products and used.

When the particles of the aluminum-based powder are large, it becomes difficult to adhere tightly to the porous resin surface, and the mass of the powder particles themselves is likely to be detached from the porous resin surface to reduce the adhesion amount. For this reason, it is preferable to use a fine aluminum-based powder, and a powder having an average particle diameter of about 50 μm or less is suitable. Furthermore, it is preferable not to contain particles having a particle size of more than 100 μm, and by removing the particles having a particle size of more than 100 μm, detachment from the surface of the porous resin can be favorably prevented. However, since aluminum is an active metal, excessively fine powders are difficult to handle. In consideration of this point, an aluminum-based powder having an average particle diameter of about 1 μm or more and about 50 μm or less is preferable. Preferably, the average particle size of the aluminum-based powder is preferably 1.0 to 20 μm, and the best is about 6 μm. The average particle diameter used here is the median diameter (D ₅₀ ), that is, the particle diameter at which the cumulative distribution is 50% by volume, according to the laser analysis method defined in Japanese Industrial Standards (JIS) 8825. It can be measured. Specifically, it can be determined as the median diameter (D ₅₀ ) of the particle size distribution measured using a laser diffraction scattering microtrack particle size distribution analyzer or the like.

(Porous resin substrate with communication holes (foamed resin))
A porous resin substrate (hereinafter, sometimes simply referred to as "foamed resin" or "substrate") serves as a mold for forming a skeleton of an aluminum-based porous body, and thus is connected in a three-dimensional manner A porous resin base having a three-dimensional network structure is used which has a skeleton and pores (communication holes) communicating in a three-dimensional manner are formed by the skeleton. By coating aluminum powder or aluminum alloy powder on the resin surface based on such a porous resin substrate to coat the surface, a powder layer corresponding to the skeleton shape of the aluminum-based porous body is formed. Since the porous resin substrate is decomposed and burned off by heating, a resin having a thermally decomposable composition that substantially does not leave a thermal decomposition residue is preferably used. As a specific example, a foam of resin such as polyolefin such as polyethylene and polypropylene, polyurethane, polystyrene, silicone, polyester, and a fiber structure (woven fabric, non-woven fabric) produced from such resin can be used. Examples of commercially available porous resins include polyurethane foam (trade name: Everlight SF) manufactured by Bridgestone Co., Ltd., and the like. In such porous resins, most components are decomposed and dissipated after pyrolysis, leaving only trace amounts of carbon (and silicon oxides, in the case of silicone resins).

(Porosity of aluminum-based porous body and porous resin base (foamed resin))
As described above, the porosity of the aluminum-based porous body may basically be an appropriate value corresponding to the application, and the appropriate range or region of the porosity is not limited in connection with brazing. In applications to be mounted on a heat exchanger for the purpose of promoting heat conduction, an aluminum-based porous body having a porosity of about 92 to 99% (ratio of volume of pores (voids) per unit volume of porous body) is used. preferable. Based on this, a porous resin substrate, which is a substrate for forming an aluminum-based porous body, also has a shape corresponding to the aluminum-based porous body, and a porosity of about 92 to 99% (porosity A porous resin having a ratio of the volume of pores (voids) per unit volume of the body is preferable. The porosity of the porous resin can also be determined by calculation from the density of the foamed resin obtained from the measurement of the volume and mass of the porous resin and the density of the resin before foaming. When the aluminum-based powder is attached to the surface of the porous resin substrate, clogging is likely to occur if the pore diameter of the porous resin is small. In the foamed resin, since the growth of air bubbles tends to be suppressed as the number of bubbles increases, a porous resin capable of causing aluminum-based powder to adhere well to the inner surface of the pore without clogging is preferred. It can be selected based on the number of cells (ppi, pore per inch: number of pores / inch) indicating the density of communicating holes. In this respect, a cell number of 8 to 40 ppi is suitable for preparing an aluminum-based porous body for promoting heat conduction. The average cell center diameter of a porous resin having a cell number of 40 ppi is 0.64 mm, and the average cell center diameter at 8 ppi is 3.18 mm. In particular, a porous resin having a cell number of 13 to 20 ppi (average cell center diameter: 1.27 to 1.95 mm) is preferable, and an aluminum-based porous body prepared using such a porous resin has pores. The fluid flow inside is smooth and the heat conduction is also good.

In the present application, the porosity (%) of the aluminum porous body is calculated on the basis of the dimensions (length, width and thickness) of the porous body and the measured values by weight measurement. It is calculated from the density, and the density of aluminum is 2.7 g / cm ³ . Further, the porosity of the urethane foam is also calculated based on the same measurement, and 1.3 g / cm ³ is adopted as the density of urethane at that time.

(Layered porous resin)
A layered porous resin is a substrate for supporting an aluminum-based powder forming a layered body, and is decomposed and dissipated by heating, so that it is pyrolyzable such that no thermal decomposition residue substantially remains in a non-oxidizing atmosphere. Layered, compact porous resins formed of resins having the composition of As a specific example of resin which comprises layered porous resin, resin, such as polyolefins, such as polyethylene and polypropylene, polyurethane, polystyrene, silicone, polyester, PVA, is mentioned, for example. It is preferable that it is layered porous resin prepared by resin which comprises a porous resin base | substrate, and resin which comprises the binder mix | blended with aluminum-type powder dispersion liquid. The thickness of the layered porous resin is not particularly limited, but it is sufficient if the porous resin substrate on which the aluminum-based powder is attached is placed on the porous resin substrate so as to have movable strength, so that residues are hardly left at heating. It is preferable to avoid such thickness. Generally, a layered porous resin having a thickness of about 0.1 to several mm is suitable, and a porous layered body is formed corresponding to the thickness of the layered porous resin. In order for the outer peripheral surface of the porous layered body formed using the layered porous resin as a base to be a dense flat surface to be handled similarly to the surface of the molten material, the number of cells of the layered porous resin is about 30 ppi or more (average cell center The diameter is preferably 0.85 mm or less), and the number of cells is preferably in the range of about 30 to 80 ppi (average cell center diameter: about 0.32 to 0.85 mm). Coating can be suitably carried out, and a porous layered body having an average pore diameter of about 1000 μm or less can be formed. An aluminum-based porous member as shown in FIG. 1 can be suitably produced using a layered porous resin having a cell number of about 39 to 60 ppi. When the pores of the layered porous resin are smaller than that of the porous resin substrate, the excess dispersion contained in the porous resin substrate is easily transferred to the layered porous resin, and the layered porous resin is The powder dispersion can be retained in the pores. When the number of cells is about 60 to 80 ppi, the ability to retain excess dispersion is high, and it is easy to form a non-porous thin film as shown in FIG.

  In the first form of the step of preparing the precursor described above, the outer peripheral surface of the porous resin substrate or the layered porous resin is brought into contact with the adhesive to attach the adhesive to the skeleton terminal of the porous resin, and the adhesive intervenes When the porous resin substrate is placed on the layered porous resin as described above, the step of bonding the porous resin substrate and the layered porous resin can be simply performed. The adhesive may be any one as long as the resins can be adhered to each other. Alternatively, the skeleton end of one porous resin may be heated and melted to be bonded. A precursor can be prepared using the porous resin of the laminated structure obtained.

(Aluminum-based powder dispersion)
As described above, the aluminum-based powder dispersion is a slurry-like liquid in which the aluminum-based powder is dispersed in a dispersion medium containing a binder. As the dispersion medium, volatile liquids such as water or alcohols can be used. When using alcohol as a dispersion medium, it is necessary to prepare an apparatus or facility environment capable of preventing the outflow to the environment, considering that the volatilized solvent is released to the environment. In this respect, it is advantageous to use water as the dispersing medium.

  In preparing an aqueous dispersion of an aluminum-based powder, a binder for adhering the aluminum-based powder to the surface of the porous resin substrate and the layered porous resin is blended. As the binder, water-soluble polymers such as polyvinyl alcohol, poly (meth) acrylic resin, water-soluble cellulose and the like can be used. An aluminum-based powder is added to and mixed with an aqueous dispersion medium containing a binder at a concentration of several percent to prepare a slurry-like dispersion. Since it is possible to suppress the sedimentation of the aluminum-based powder particles and stabilize the dispersion state of the particles by blending a dispersing agent as necessary, a dispersion liquid with high stability can be obtained. Furthermore, the surfactant is effective in suppressing the progress of oxidative corrosion on the surface of the aluminum-based powder due to contact with water, adsorbs on the surface of the powder particle to form a layer, and enhances chemical stability. While suppressing corrosion, the dispersibility of the aluminum-based powder and the viscosity stability of the dispersion are enhanced. Moreover, you may add the antifoamer etc. which suppress the foam which generate | occur | produces at the time of stirring, and the component which contributes to sintering promotion of powder in the case of the heating which forms frame | skeleton of an aluminum-type porous body.

  The particles of the aluminum-based powder have an oxide film on the surface. When heated to the liquidus temperature or higher, the aluminum (or aluminum alloy) inside melts (liquidizes) and thermally expands to gradually rupture the oxide film. The powder particles are bonded to each other by molten aluminum (or aluminum alloy) which has spread by breaking the coating. However, if the heating temperature is less than the liquidus temperature, diffusion bonding can not proceed when the oxide film is maintained, and the powder particles are not bonded to each other. In bonding aluminum-based powder particles, a component that improves the wettability of molten aluminum to the oxide film and a component that can suppress the formation of the oxide film are useful. In this regard, surfactants having functional groups that react with the particle surface of the aluminum-based powder are useful and are preferably incorporated into the dispersion. Surfactants such as anionic surfactants, cationic surfactants, amphoteric surfactants and nonionic surfactants are useful, and specifically, silane surfactants, phosphate ester surfactants And carboxylic ester surfactants, catechol surfactants, amine surfactants, thiol surfactants, alkyne surfactants, alkene surfactants and the like. In particular, phosphoric acid ester, polyoxyethylene alkylphenolic acid, epoxy compound or phosphoric acid ester in which acrylic compound and acrylic acid and phosphoric acid are esterified is preferable in terms of reactivity at high temperature, and aliphatic having about 10 to 18 carbon atoms Phosphoric acid monoesters are more preferred. The phosphate ester acts to protect the surface of the aluminum-based powder and to suppress oxidation. The amount of the surfactant added is preferably 0.1 to 10.0 parts by mass with respect to 100 parts by mass of the dispersion medium containing the binder, which is preferable from the viewpoint of preventing the corrosion of the aluminum-based powder particles, Preferably, it may be 0.5 to 5.0 parts by mass.

  Examples of aliphatic phosphoric monoesters include isopropyl acid phosphate, butyl acid phosphate, butoxyethyl acid phosphate, hexyl acid phosphate, octyl acid phosphate, 2-ethylhexyl acid phosphate, nonyl acid phosphate, decyl acid phosphate, and dodecyl acid phosphate. Compounds such as tridecyl acid phosphate, isotridecyl acid phosphate, tetradecyl acid phosphate, hexadecyl acid phosphate, stearyl acid phosphate, phenyl acid phosphate, propylphenyl acid phosphate, butylphenyl acid phosphate and butoxyethoxyethyl acid phosphate can be mentioned. . Any one of such compounds may be used alone, or two or more may be mixed and used. Also, these polymers may be included.

  The oxide film of the aluminum-based powder can be thinned by the etching effect when the dispersion is adjusted to be acidic. When acidification is performed using phosphoric acid, fluoride, etc., the etching effect is high, but hydrogen may be generated by etching of the oxide film, and when this is present in the powder particles as bubbles, the aluminum-based powder is a porous resin Inhibits adhesion to surfaces. In consideration of such points, it is preferable to prepare a dispersion of an aluminum-based powder in consideration of pH and, if necessary, to use an aluminum corrosion inhibitor.

(Adjustment of adhesion amount by adjusting viscosity)
The amount of the aluminum-based powder to be attached to the porous resin substrate and the layered porous resin can be adjusted by adjusting the viscosity of the aluminum-based powder dispersion to be used. That is, when the viscosity of the dispersion is high, the amount of the aluminum-based powder adhering to the surfaces of the porous resin substrate and the layered porous resin increases, and when the viscosity is low, the amount of the aluminum-based powder adhering thereto decreases. If the adhesion amount is excessive, mold deformation is likely to occur during subsequent heating, so if the adhesion amount of the aluminum-based powder adhering to the surface of the porous resin substrate is adjusted to about 500 μm or less, the mold distortion is It is suppressed to obtain an aluminum-based porous body having a skeleton of a suitable thickness. If the skeleton of the aluminum-based porous body is thin, the strength is insufficient, and the thickness of the skeleton is preferably about 50 to 500 μm. Therefore, the amount of powder attached to the porous resin is about 100 to 1000 μm Is preferred. From this viewpoint, the viscosity of the dispersion liquid is preferably about 20 Pa · s or more and about 1000 Pa · s or less (value at 50 rpm) at 25 ° C., and is preferably about 50 Pa · s or more and about 500 Pa · s or less Is more preferred. The viscosity can be measured using a viscometer. For example, using a viscometer manufactured by Toki Sangyo Co., Ltd. (trade name: TVB 10 type), the twist angle of the two slit disks by viscosity torque Can be detected and this value can be converted to viscosity.

  The surface of the aluminum-based powder is obtained by impregnating the slurry-like aluminum-based powder dispersion prepared as described above with the porous resin, removing the excess slurry from the porous resin substrate to which the dispersion has permeated, and drying. The porous resin substrate adhered to If necessary, the porous resin substrate immersed in the dispersion may be upside down or lightly compressed to promote penetration into the whole. Further, the excess dispersion remaining in the pores of the porous resin substrate pulled up from the dispersion can be discharged by squeezing using a squeeze roll or the like. It is possible to adjust the amount of the aluminum-based powder adhering to the surface of the porous resin substrate by the degree of squeezing adjusted by the roll distance of the squeeze roll, and by performing a constant squeezing process It is also possible to suppress The same applies to a layered porous resin, and a porous resin substrate and a layered porous resin adhered to each other. For each of the porous resin substrate and the layered porous resin, dispersions of different viscosities may be used, but using the same dispersion is simple and efficient.

  Drying of the porous resin substrate and the layered porous resin coated with the aluminum-based powder dispersion may be accompanied by heating or non-heating. When heat drying is performed, it is preferable to dry at a temperature at which the porous resin does not deform. Since heating for thermal decomposition of the porous resin and the layered porous resin is performed after drying, the heating temperature may be set so that drying and thermal decomposition are performed continuously. However, when the vaporized dispersion medium causes a problem in the heating device, a heating device capable of quickly discharging the vaporized material is used. By drying, a powder binder that is a source of forming a skeleton of the aluminum-based porous body and a skeleton of the porous layered body is formed on the surface of the porous resin substrate and the layered porous resin. When the excess aluminum-based powder dispersion contained in the layered porous resin is dried, the aluminum-based powder is deposited in the pores of the layered porous resin to increase the thickness of the skeleton formed after heating. As the amount of excess dispersion increases, the lower pores of the layered porous resin are filled with the dispersion, and the lower pores after drying are filled with the binder of the aluminum-based powder. Therefore, the bottom of the aluminum-based porous layered body formed after heating becomes a thin film as shown in FIG. 2 and becomes a substantially impermeable smooth surface.

  In the second form of the step of preparing the precursor described above, in the drying step, the porous resin substrate to which the aluminum-based powder dispersion is applied is placed on the layered porous resin to which the aluminum-based powder dispersion is applied. To do This is a form configured to perform drying and thermal decomposition continuously, and it is possible to continuously perform drying and thermal decomposition in any of the first and second embodiments described above. is there. In addition, when drying is performed in a state in which the porous resin substrate to which the aluminum-based powder dispersion is applied and the layered porous resin to which the aluminum-based powder dispersion is applied are in contact, the base of the aluminum-based porous body skeleton is obtained. Since the powdery binder and the powdery binder forming the basis of the porous layered body are joined and integrated, the continuity between the aluminum-based porous body skeleton obtained after heating and the porous layered body is high. However, the second embodiment may be modified so that the porous resin substrate and the layered porous resin are dried, and then the porous resin substrate is placed on the layered porous resin and introduced into the heating step. Alternatively, one of the porous resin substrate and the layered porous resin may be dried first, and the porous resin substrate may be placed on the layered porous resin and charged in the heating step before the other is dried.

(Pyrolytic decomposition of porous resin, framework formation of aluminum-based porous body and integration of layered body)
The precursor prepared as described above, that is, the porous resin substrate and the layered porous resin with the aluminum-based powder adhering to the surface is heated (heating step), the porous resin substrate and the layered porous resin Are burned off by thermal decomposition, and further, the fusion of the aluminum-based powder is advanced. Since the powder binding material which is the origin of the aluminum-based porous body and the porous layered body is heated and melted in a state where they are in contact with or integrated with each other, the produced aluminum-based porous body and the porous layered body are favorable. Bonded by metal bonding. That is, the aluminum-based porous body and the porous layered body are integrally formed.

  The porous resin can be burnt off generally at about 400 to 550 ° C., and organic components such as adhesives and binders can also be burnt out by this heating. Depending on the composition of the porous resin used, the heating temperature to be burned off may be set appropriately, and in the case of polyurethane foam, about 450 to 550 ° C. is preferable. Since the thermal decomposition temperature of the porous resin is considerably lower than the melting temperature of aluminum, the particles of the aluminum-based powder are not bonded to each other at a heating temperature at which the porous resin decomposes and is lost, and a strong framework is formed. Absent. Therefore, in the heating step, in order to impart strength to the skeleton of the aluminum-based porous body, the heating temperature is further raised to melt the powder particles, and the powder particles are bonded together by fusion. Even if the temperature is raised to a temperature at which the aluminum-based powder is fused without setting the temperature for thermally decomposing the porous resin, thermal decomposition of the porous resin can be progressed during that time.

  The aluminum-based powder particles fuse (i.e., melt and integrate) with each other by heating above the melting point of aluminum (660.4 ° C.) or the liquidus temperature of the aluminum alloy. Therefore, by cooling thereafter to solidify the aluminum-based melt (cooling step), the particles are firmly bonded to each other, and the bonding formation by fusion is completed. Along with the bonding between particles, the bonding between the framework of the aluminum-based porous body and the framework of the porous layered body is also fixed. The high melting point oxide film (alumina) is encased in molten aluminum or aluminum alloy and functions as a core inside the skeleton formed by bonded particles. The heating temperature preferably does not exceed 100 ° C. or more above the melting point or liquidus temperature.

In addition, in order to prevent the oxidation of the aluminum-based powder, it is appropriate that the heating step is all performed in a non-oxidizing atmosphere with a small amount of oxygen. Specifically, in an inert gas atmosphere such as nitrogen gas or argon gas, in a reducing gas atmosphere such as hydrogen gas or hydrogen mixed gas, or under reduced pressure (vacuum) of about 10 ^-3 Pa or less It is good to do in the In order to advance the sintering of the aluminum-based powder particles by utilizing the loss of the oxide film, it is important to prevent oxidation.

  Since the integration of the aluminum-based porous body and the porous layered body occurs at the time of melting of the aluminum-based powder particles by heating, strictly speaking, the layered porous resin and the porous medium are subjected to the thermal decomposition of the porous resin. It does not have to be in contact with the resin substrate. However, since the skeleton-formed body of aluminum-based powder particles after the porous resin and the binder are burned off has poor adhesion between the particles and is easily broken, thermal decomposition of the porous resin and the layered porous resin and It is a realistic method to heat the precursor so as to continue the melting and integration of the powder.

In the aluminum alloy, since a liquid phase is formed according to the temperature in a temperature region which is lower than the liquidus temperature and higher than or equal to the solidus temperature, sintering by the atomic diffusion or Bonding through the phases can proceed. That is, in the temperature range of about 600 ° C. or more and less than 660.4 ° C., in particular, in the range where the difference from the liquidus temperature is 20 ° C. or less, bonding of aluminum alloy powder particles having defects in the oxide film is possible. It will be the temperature. As the heating temperature of the aluminum alloy powder approaches the liquidus temperature, the amount of liquid phase generated increases, so if the oxide film is thin and easy to burst, fusion occurs as in the case of heating above the liquidus temperature. The particles can bind each other and the particles and the layered body. Heating under vacuum is effective in facilitating sintering, and application of a degree of vacuum of 10 ⁻³ Pa or more is preferable. The surfactant bound to the surface of the aluminum-based powder suppresses the progress of oxidation on the surface.

  By melting the aluminum-based powder, the powder particles are integrated to form a skeleton of the aluminum-based porous body and a skeleton of the porous layered body, and at the same time, these skeletons are connected to each other, so they are cooled and melted. Solidify the material (cooling step). That is, it is cooled to a temperature lower than the melting point (or liquidus temperature), generally to room temperature (about 1 to 30 ° C.). Thereby, the aluminum (or aluminum alloy) thermally expanded during heating is shrunk by cooling, and the skeletal shape is fixed while maintaining the shape along the three-dimensional network structure of the porous resin. Then, an aluminum-based porous member is obtained, in which the flat porous layered body and the aluminum-based porous body are integrally formed, and the porous layered body is integrally formed along the outer periphery of the aluminum-based porous body. The framework of the porous layered body is continuous with the framework of the aluminum-based porous body by metal bonding. Inside the framework, there may be voids due to the porous resin. Since the formation of the metallographic structure is affected by the cooling rate, the cooling rate may be set appropriately in consideration of physical properties such as material strength.

  Thus, the aluminum-based porous member in which the aluminum-based porous body and the porous layered body are integrally formed is manufactured. The porosity of the porous layered body more compact than the aluminum-based porous body is smaller than that of the aluminum-based porous body, and is about 20 to 95%. The skeletons of the aluminum-based porous body and the porous layered body are formed from the same aluminum-based powder binder, and thus have the same composition as the raw material aluminum-based powder. The skeleton of the aluminum-based porous body may include voids generated by thermal decomposition of the porous resin. The framework of the porous layered body may also include voids from the resin. In the thin film formed from the excess aluminum-based powder dispersion, since the voids derived from the resin are small, the bulk density is higher than the skeleton of the porous layered body, and generally becomes about 90 to 99% of the true density, and is impermeable Approach to

  Since the porous layered body is provided not by adhesion through an organic binder or the like but by integral formation with an aluminum-based porous body, a component (such as carbon, carbide, oxide, etc.) which inhibits joining at the time of brazing and joining It is preferable at the point that there are few components which produce a heating residue. In addition, since the porous layered body is dense, its outer peripheral surface is flat, and is similar to the multi-hole plate in that handling similar to a smooth surface is possible. Therefore, it is easy to make close contact with the surface to be joined in brazing. This advantage is even more pronounced when a thin film is formed from the excess powder dispersion below the porous layered body. When the shape or size of the aluminum-based porous member after production is changed, the cutting process may be appropriately selected and applied from techniques generally used for cutting of materials. For example, it can process to a desired shape and a size using cutting techniques, such as electrical discharge machining, laser processing, a wire saw, and a round blade. Electrical discharge machining is superior in machining precision.

(Brazed joint using aluminum based porous member)
An aluminum-based porous member in which a dense porous layered body is integrated is such that a brazing composition is present between a to-be-joined surface such as a plate or a tube and a porous layered body to be in close contact with each other. It is joined to a to-be-joined surface by heating to brazing temperature in the assembled state. The porous layered body is dense enough to hold paste and the like between the skeletons in the vicinity of the outer peripheral surface, so that the application of the brazing composition to the porous layered body is easy. The brazing temperature may be set to a temperature equal to or higher than the liquidus temperature in the composition of the brazing material, preferably, a temperature at which the difference from the liquidus temperature is within about 10 ° C. The heating time at the brazing temperature is desirably minimized, and specifically, about 0.5 minutes to 10 minutes is preferable. After heating at the brazing temperature is completed, cooling is promptly performed to prevent erosion due to excessive heating, whereby an aluminum-based porous member suitably brazed to the surface to be joined can be obtained.

  The configuration of the aluminum-based porous member is advantageous in terms of the protective properties of the porous body and the ease of handling, and therefore can be used in applications not used for bonding. The above advantages can be obtained by using other metallic or non-metallic sheet that can be joined with aluminum instead of the porous layered body, but by using the same composition, it is thermally conductive Local changes are avoided.

  EXAMPLES The present invention will be more specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1
A 25 mm long, 70 mm wide, 20 mm thick polyurethane foam (trade name: Everlight SF, manufactured by Bridgestone Co., Ltd.) was prepared as a base made of a foamed resin having a three-dimensional network structure (porous resin base) . The porosity (the ratio of the volume of the communicating holes to the total volume) of this foamed resin was 95%, and the size of the communicating holes was 3000 μm in terms of the equivalent circle diameter. Further, as a resin substrate for the porous layered body, polyurethane foam (size of communication hole: about 500 μm in equivalent circle diameter) having a length of about 25 mm, a width of about 70 mm and a thickness of about 1 mm was prepared. An adhesive for resin is applied to the outer peripheral surface of this one side, and one surface (surface of 25 mm long × 70 mm wide) of the above-mentioned porous resin substrate is brought into contact to cure the adhesive, thereby two types of polyurethane I bonded the foam.

  Next, in order to prepare an aluminum powder dispersion (slurry), polyvinyl alcohol (PVA, trade name: Gohsenol GH-23, manufactured by Nippon Gohsei Chemical Co., Ltd.) is dissolved in ion exchange water as a binder, and the concentration is 1 mass. % PVA aqueous solution was prepared. This aqueous solution was mixed with an aluminum powder having a particle size of 10 μm or less (trade name: 25E, manufactured by Eka Granular) at a mass ratio of 3: 5 to prepare an aluminum powder dispersion.

  After immersing the polyurethane foam adhered as described above in the prepared aluminum powder dispersion, it was taken out, and the polyurethane foam was squeezed using a device equipped with a pair of squeeze rolls to remove excess aluminum powder dispersion. Under the present circumstances, the application amount of the dispersion liquid was adjusted with the squeeze degree so that the adhesion amount of the aluminum powder with respect to 1 L of volume of a polyurethane foam will be in the range of 44.0-100.0 g / L. The polyurethane foam to which the aluminum powder adhered was dried at 80 ° C. for 120 minutes to obtain a precursor of an aluminum porous member.

The dried precursor is placed in a furnace, and the heating temperature is raised to 665 ° C. (melting point of aluminum powder used: 660.4 ° C.) in a reduced pressure atmosphere (vacuum atmosphere) at a pressure of 10 ⁻³ Pa. And heated at 665 ° C. for 210 minutes. After this, cooling was performed while maintaining a vacuum atmosphere. When the heating plate was taken out of the furnace and confirmed, the polyurethane foam was burned off and a framework of the aluminum porous body was formed, and a porous layered body made of aluminum was formed, and the framework of the porous layered body and the aluminum porous The skeleton of the body was a continuous one-piece. The porosity of the aluminum porous body in the aluminum porous member thus obtained was 95%, and the thickness of the porous layered body was about 1 mm. The porous layered body had a dense structure in which the space between the frameworks was narrow, and the tips of the frameworks on the lower outer peripheral surface (the surface opposite to the aluminum porous body) were flat.

Example 2
The following operations were carried out using the same urethane foam and aluminum powder dispersion as in Example 1.

  After immersing each of the two types of urethane foam in the aluminum powder dispersion, it is taken out, and the urethane foam which is a porous resin substrate is squeezed in the same throttling degree as in Example 1 using an apparatus equipped with squeeze rolls. To obtain a porous resin substrate coated with an aluminum powder dispersion. For the urethane foam for porous layered body, place the excess aluminum powder dispersion in the foam resin on a heating pan, place the porous resin substrate with the aluminum powder adhered on it, and place it at 80 ° C. After drying for 120 minutes, a precursor of an aluminum porous member was obtained.

  The dried precursor was placed in a furnace, and heating and cooling were performed under the same conditions as in Example 1. After cooling, the superheated pan was taken out of the furnace and confirmed. As in Example 1, the urethane foam was burned off and a framework of the aluminum porous body was formed, and a porous layered body made of aluminum was formed, and the pores were porous. The framework of the porous layered body and the framework of the aluminum porous body were continuous and integral. In the lower part of the formed porous layered body, a substantially continuous thin film was formed to occlude between the skeletons, and the bottom was a smooth surface.

<Brazed>
An aluminum plate (JIS-A1050) having a thickness of 0.8 mm was prepared, cut into a size of 30 mm × 100 mm, and used as a material to be joined in the following brazing.
The outer peripheral surface of the porous layered body of the aluminum porous member obtained in each of Examples 1 and 2 was compared with an aluminum paste brazing material manufactured by Toyo Aluminum Co., Ltd. (TOYAL HYPERBAZE (registered trademark), product name: AF524F). The brazing material was deposited to a thickness of about 100 μm and dried in the air at 80 ° C. for about 10 minutes. The porous layered body to which the brazing material was attached in this manner was brought into intimate contact with the aluminum plate prepared as the material to be joined. This was introduced into a brazing furnace and heated in a nitrogen atmosphere (oxygen concentration: 50 ppm or less). At this time, the temperature in the furnace was raised at 10 ° C./min from room temperature to 590 ° C., and then held at 590 ° C. for 5 minutes. Thereafter, the inside of the furnace was rapidly cooled, and the porous aluminum member and the workpiece were recovered from the furnace which had returned to room temperature. As a result, an aluminum porous member to which a material to be joined was brazed was obtained in any of the examples. The bonding between the aluminum porous member and the aluminum plate as a bonding material was in a strong state in any of the examples.

  Since it is possible to perform good brazing of the aluminum-based porous body by a simple operation and simplify complicated assembly and brazing operations, aluminum incorporated as a component such as a heat dissipating fin of a heat exchanger It is useful as a porous body. Since the aluminum-based porous body applied to the application utilizing heat conductivity can be provided as a product easy to bond and handle, it can be provided as a highly versatile product.

1,1 'Aluminum-based porous member 2 Aluminum-based porous body 3 porous layered body 4 thin film

Claims (10)

An aluminum-based porous body composed of aluminum or an aluminum alloy,
And a porous layered body integrally formed along the outer periphery of the aluminum based porous body, wherein the porous layered body has the same composition as the aluminum based porous body, and the aluminum based porous body Aluminum-based porous member having smaller pore size.   The aluminum-based porous member according to claim 1, wherein the porous layered body has a flat shape having an average pore diameter of 1000 μm or less and an average thickness of 10 μm or more and 1 mm or less based on the equivalent circle diameter.   The aluminum-based porous member according to claim 1 or 2, wherein a shape of the aluminum-based porous body is a rectangular solid.   Furthermore, it has an aluminum-based thin film formed on the outer peripheral surface of the porous layered body on the opposite side to the aluminum-based porous body, and the aluminum-based thin film has the same composition as the aluminum-based porous body. The aluminum-based porous member according to any one of Items 1 to 3.   The aluminum-based porous member according to any one of claims 1 to 4 for bonding to a heat exchanger in the porous layered body, wherein the porosity of the aluminum-based porous body is 92 to 99%. . A porous resin substrate, a layered porous resin having a pore diameter smaller than that of the porous resin substrate, and adjacent to the porous resin substrate, and aluminum adhering to the surfaces of the porous resin substrate and the layered porous resin Preparing a precursor having a powder system;
Heating the precursor to thermally decompose the porous resin substrate and the layered porous resin, and melt the aluminum-based powder to form an aluminum-based porous body and a porous layered body;
And cooling the aluminum-based porous body and the porous layered body produced in the heating step to integrally form the porous layered body and the aluminum-based porous body. The preparation process is
Preparing an aluminum-based powder dispersion in which the aluminum-based powder is dispersed in a dispersion medium;
Bonding the porous resin substrate to the layered porous resin;
Applying the aluminum-based powder dispersion to the surfaces of the porous resin substrate and the layered porous resin bonded in the bonding step;
The method according to claim 6, further comprising the steps of: drying the porous resin substrate to which the aluminum-based powder dispersion has been applied and the layered porous resin to remove the dispersion medium to obtain the precursor. Method of manufacturing a porous member The preparation process is
Preparing an aluminum-based powder dispersion in which the aluminum-based powder is dispersed in a dispersion medium;
A first application step of applying the aluminum-based powder dispersion to the surface of the porous resin substrate;
A second application step of applying the aluminum-based powder dispersion to the layered porous resin;
The porous resin substrate coated with the aluminum-based powder dispersion is placed on the layered porous resin coated with the aluminum-based powder dispersion, and the porous resin substrate and the layered porous resin are dried. The drying process which obtains the said precursor by removing a dispersion medium, The manufacturing method of the aluminum-type porous member of Claim 6.   In the coating step or the second coating step, the layered porous resin is coated with the aluminum-based powder dispersion so as to excessively include the aluminum-based powder dispersion in pores. The manufacturing method of the aluminum-type porous member as described in 4.   The method for manufacturing an aluminum-based porous member according to any one of claims 6 to 9, wherein the aluminum-based powder is an aluminum powder or an aluminum alloy powder and has an average particle diameter of 1 μm to 50 μm.

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