JP2019090064A - Aluminum-based porous member and method for producing the same - Google Patents

Abstract

To provide an aluminum-based porous member in which an aluminum-based porous body is braze-joined 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 lamellar body which has the same composition as that of the aluminum-based porous body and is integrally formed along the outer periphery of the aluminum-based porous body. In a step of heating a precursor having a porous resin, a resin sheet in contact with the porous resin and aluminum powder attached to the surfaces of the porous resin and the resin sheet, the porous resin and the resin sheet are thermally decomposed, and the aluminum powder is melted to produce a skeleton of the aluminum-based porous body and the lamellar body. In a cooling step of cooling the produced skeleton of the aluminum-based porous body and the lamellar body, the lamellar body and the skeleton of the aluminum-based porous body are integrally formed.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 has an aluminum-based porous body composed of aluminum or an aluminum alloy, and the same composition as the aluminum-based porous body, and the aluminum-based porous body And a layered body integrally formed along the outer circumference of the frame.

  The layered body is preferably flat and has an average thickness of 10 μm or more and 1 mm or less. In addition, the shape of the aluminum-based porous body is advantageously a rectangular parallelepiped shape from the viewpoint of versatility, and the aluminum-based porous body has a porosity of 90% to 98%, and the layered body The porosity is 5% or more and less than 90%. When the porosity of the aluminum-based porous body is 92 to 98%, it is useful as an aluminum-based porous member for bonding to a heat exchanger in the layered body.

  Further, according to one aspect of the present invention, a method of manufacturing an aluminum-based porous member includes a porous resin, a resin sheet in contact with the porous resin, and aluminum attached to the surfaces of the porous resin and the resin sheet. Heating the precursor having the base powder to thermally decompose the porous resin and the resin sheet, and melting the aluminum-based powder to form a skeleton and a layered body of the aluminum-based porous body; The gist of the invention is that the method further comprises the steps of: cooling the skeleton and the layered body of the aluminum-based porous body generated in the heating step; and integrally forming the layered body and the skeleton of the aluminum porous body.

  The method for producing an aluminum-based porous member further includes a preparation step of preparing the precursor, and 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. A bonding step of bonding the porous resin to the resin sheet, a coating step of applying the aluminum-based powder dispersion to the surfaces of the porous resin and the resin sheet bonded in the bonding step, and the aluminum It can be favorably carried out according to an embodiment having a drying step of obtaining the precursor by drying the porous resin and the resin sheet to which the system powder dispersion has been applied and removing the dispersion medium. Alternatively, the preparing step is a preparing step of preparing an aluminum-based powder dispersion liquid in which the aluminum-based powder is dispersed in a dispersion medium, and a first coating step of applying the aluminum-based powder dispersion liquid on the surface of the porous resin A second applying step of applying the aluminum-based powder dispersion on the surface of the resin sheet, and the porous resin applied with the aluminum-based powder dispersion, the resin having the aluminum-based powder dispersion applied thereon The method can be favorably implemented by a method comprising the steps of: drying on the sheet, drying the porous resin and the resin sheet, and removing the dispersion medium to obtain the precursor. Further, the preparing step is a preparing step of preparing an aluminum-based powder dispersion in which the aluminum-based powder is dispersed in a dispersion medium, and the porous such that the porous resin excessively includes the aluminum-based powder dispersion. A coating step of coating the aluminum-based powder dispersion on the surface of a resin, the porous resin coated with the aluminum-based powder dispersion is placed on the resin sheet, and a surplus aluminum-based powder dispersion is the resin sheet And the step of drying the porous resin and the resin sheet to remove the dispersion medium to obtain the precursor.

  The aluminum-based powder dispersion preferably has a viscosity at 25 ° C. of 20 to 1000 mPa · s or less (rotational speed: 50 rpm). The aluminum-based powder is an aluminum powder or an aluminum alloy powder, and preferably has an average particle diameter of 1 μm to 50 μm.

  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 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.

  From such a thing, in order to join an aluminum-type porous body instead of a fin material to heat-transfer surfaces and heat sources, such as a heat exchanger, the layered body like aluminum or aluminum alloy foils or sheets is aluminum-based An aluminum-based porous member having a structure attached to a porous body is useful. Since the tip of the three-dimensional network skeleton constituting the porous body is substantially point-like, brazing at the framework end is less accurate, and this point indicates that the brazing composition is bonded to the surface to be joined. Even when applied, the same applies when applied to the skeletal end. 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".

  The layered body is a flat element in the form of a foil or a sheet and is a member to be joined to a surface to be joined such as a heat exchanger. The layered body can be formed by bonding a separately prepared flat plate material to the skeleton of the aluminum-based porous body using an adhesive, but the skeleton of the aluminum-based porous body is formed. It is possible to simultaneously form a layered body in the manufacturing process. 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 an embodiment of the aluminum-based porous member, one in which the layered body M is integrated on one surface (lower surface) of the aluminum-based porous body P as shown in FIG. 1 can be mentioned. An aluminum porous member configured based on the mass P is advantageous in terms of versatility. The composition for brazing is applied to the layered body M of the aluminum-based porous member 1 and brought into intimate contact with the body to be bonded, and heated to the brazing temperature while maintaining a gap-free state, A bond is formed. Therefore, for example, the aluminum-based porous body is joined via the layered body by arranging and brazing the member in a flat tube which constitutes the main part of the heat exchanger, and good heat transfer through this joining is achieved. Is possible.

  The thickness of the layered body integrated with the aluminum-based porous body can be appropriately set as needed. However, if the 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. In order to function well, the average thickness may be set to about 2 mm or less, preferably about 10 μm to about 1 mm, and more preferably about 10 μm to about 300 μm.

  The layered body is formed utilizing an aluminum-based powder which is a raw material of the aluminum-based porous body, and has substantially the same composition as the aluminum-based porous body. That is, the layered body is made of aluminum or an aluminum alloy. A layered body made of aluminum is preferred in view of high thermal conductivity. For the aluminum alloy, it is preferable to appropriately select a composition in a range in which the thermal conductivity is good.

  A brazing composition generally used for joining aluminum to a layered body made of aluminum is applied to the layered body, and brazing is performed by assembling and heating an aluminum-based porous member on a surface to be joined. A bond is formed. The brazing composition is a paste-like or flowable composition containing a brazing material powder and a flux.

  The layered body as described above can be integrally formed with the aluminum-based porous body in the production process of the aluminum-based porous body, and in this case, a precursor layered body for integrally forming the layered body is used. That is, along with the completion of the aluminum-based porous body, the layered body produced from the precursor layered body is integrally formed to obtain an aluminum-based porous member. Since the integrally formed layered body is continuous with the skeleton of the aluminum-based porous body, and the aluminum-based porous body is supported by the layered body, the obtained aluminum-based porous member becomes easy to handle and is being transported It is possible to reduce the breakage of the skeleton constituting the aluminum-based porous body, and the loss of the skeleton and the powder fall off 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.

(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. Generally, the porosity is about 80 to 98%, 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, it has a porosity of about 90 to 98% (proportion of volume of pores (void) per unit volume of porous body) from the viewpoint of contact efficiency with fluid, air flow resistance, etc. A 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 (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 production process of such an aluminum-based porous body, the heating step proceeds in a state where the porous resin to which the aluminum-based powder is attached and the layered body are in contact in the process of producing 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. In order to carry out such a heating step, it is useful to prepare a precursor in which a porous resin having an aluminum-based powder attached to its surface and a precursor layered body for forming a layered body are in contact.

  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.

  In the wet method, the precursor layered body can be easily prepared using an aluminum-based powder dispersion. For example, the aluminum-based powder can be bound in layers by drying the aluminum-based powder dispersion on a non-permeable sheet. By using this method, it is possible to easily prepare a precursor in which a porous resin having an aluminum-based powder attached to the surface and a precursor layered body are in contact with each other. That is, it is possible to provide a precursor having a porous resin, a resin sheet in contact with the porous resin, and the porous resin and an aluminum-based powder attached to the surface of the resin sheet, and aluminum adhering to the surface of the resin sheet in layers. The system powder is a precursor layered body. The precursor is heated to thermally decompose the porous resin and the resin sheet, and the aluminum-based powder is melted to form a skeleton and a layered body of the aluminum-based porous body, which are continuous. Since the skeleton and the layered body of the aluminum-based porous body to be formed are solidified in the cooling step, the layered body and the skeleton of the aluminum porous body are integrally formed. The resin sheet may be any sheet that is impermeable and thermally decomposable, and thus the precursor can be easily prepared.

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.
In the 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 to a resin sheet, a surface of a bonded porous resin and a resin sheet The coating step of applying the aluminum-based powder dispersion to the substrate, and the drying step of drying the porous resin and the resin sheet to which the aluminum-based powder dispersion has been applied to remove the dispersion medium are sequentially carried out to obtain a precursor. Be The step of applying the aluminum-based powder dispersion to the surfaces of the porous resin and the resin sheet is achieved by immersing the porous resin and the resin sheet 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 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, the surface of a resin sheet A second coating step of coating the aluminum-based powder dispersion liquid on the surface, and the porous resin coated with the aluminum-based powder dispersion liquid on the resin sheet coated with the aluminum-based powder dispersion liquid; The drying step of drying the sheet to remove the dispersion medium is carried out, whereby a precursor is obtained. Since the coating step is individually performed on each of the porous resin and the resin sheet, the amount of coating can be easily adjusted, and in particular, the thickness of the precursor layered body formed on the resin sheet can be accurately adjusted.

  As a third embodiment, a preparation step of preparing an aluminum-based powder dispersion in which an aluminum-based powder is dispersed in a dispersion medium, aluminum on the surface of the porous resin such that the porous resin contains an excess of the aluminum-based powder dispersion Coating step of applying a powder-based powder dispersion, and a porous resin coated with an aluminum-based powder dispersion is placed on a resin sheet, and excess aluminum-based powder dispersion is deposited on the resin sheet; The drying process is performed to dry the quality resin and the resin sheet to remove the dispersion medium, whereby a precursor is obtained. This condition can be set because the coating amount of the aluminum-based powder dispersion and the surplus amount contained in the resin can be adjusted by the degree of pressing of the porous resin after immersion in the aluminum-based powder dispersion. For example, the precursor can be obtained by a very simple operation.

(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 with communication holes (foamed resin))
A porous resin (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 has a three-dimensionally linked skeleton A porous resin having a three-dimensional network structure is used, in which pores (communication holes) communicating three-dimensionally are formed by the skeleton. An aluminum powder or an aluminum alloy powder is attached to the resin surface based on such a porous resin to form a powder layer corresponding to the skeleton shape of the aluminum-based porous body. Since the porous resin is decomposed and burned off by heating, a resin having a pyrolyzable 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 (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 98% (ratio of volume of pores (voids) per unit volume of porous body) is preferable . Based on this, a porous resin 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% (porous A porous resin having a ratio of the volume of pores (voids) per unit body volume is preferred. 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, 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 air without clogging is as follows. It can be selected based on the cell number (ppi, pore per inch: number of pores / inch) indicating the density of the communication 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 is The fluid flow 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.

(Resin sheet)
The resin sheet is for supporting the aluminum-based powder that forms the precursor layer body, and is decomposed and burned off by heating, so that the composition has such a thermal decomposition property that substantially no thermal decomposition residue remains in a non-oxidizing atmosphere. An impermeable sheet formed of a resin having the following is preferably used. As a specific example of resin which comprises a resin sheet, resin, such as polyolefins, such as polyethylene and polypropylene, polyurethane, polystyrene, silicone, polyester, PVA, is mentioned, for example. It is preferable that it is a resin sheet prepared by resin which comprises porous resin, and resin which comprises the binder mix | blended with aluminum-type powder dispersion liquid. There is no particular limitation on the thickness of the resin sheet, but it is sufficient if the thickness has a movable strength by placing the porous resin to which the aluminum-based powder is attached, so that the thickness is excessive so that residues do not easily remain at the time of heating. It is preferable to avoid Generally, a thickness of about 0.1 to several mm is suitable. In the first embodiment of the step of preparing the precursor, the step of bonding the porous resin and the resin sheet can be simply performed by using the resin sheet having the adhesive layer on one side. The adhesive may be any one as long as the resins can be adhered to each other.

(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 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 has a porous resin surface Inhibit adhesion to 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 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 aluminum-based powder adhering to the surface of the porous resin increases, and when the viscosity is low, the amount of aluminum-based powder adhering is decreased. 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 porous resin surface is adjusted to about 500 μm or less, mold distortion is suppressed. Thus, an aluminum-based porous body having a skeleton of a suitable thickness is obtained. 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 more preferably about 50 to 300 Pa · s. 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.

  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 in which the dispersion has permeated into the whole, and drying, the aluminum-based powder is formed on the surface. An attached porous resin is obtained. If necessary, the porous resin 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 pulled up from the dispersion can be discharged by squeezing using a squeeze roll or the like. The amount of aluminum-based powder adhering to the surface of the porous resin can be adjusted by the degree of squeezing adjusted by the roll distance of the squeeze roll, and by performing the constant squeezing process, the variation of the adhering amount is suppressed It is also possible. The same applies to a porous resin to which a resin sheet is adhered. In addition, in order to apply | coat an aluminum-type powder dispersion liquid in order to produce | generate a precursor layer body on a resin sheet, the conventional application method applied to a slurry-like liquid may be utilized, for example, a brush, a spatula, a roll. The dispersion can be suitably applied using a coater or the like. Therefore, as long as the target coating is possible, the viscosity of the dispersion does not need to be particularly limited, and dispersions of different viscosities may be used, but using the same dispersion simplifies the operation. It is efficient.

  Drying of the porous resin and resin sheet 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 resin sheet 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 serving as the origin of the skeleton of the aluminum-based porous body is formed on the surface of the porous resin, and a precursor layer body composed of the powder binder is formed on the resin sheet. Is provided.

  In the second form of the step of preparing the precursor described above, in the drying step, the porous resin to which the aluminum-based powder dispersion is applied is placed on the resin sheet to which the aluminum-based powder dispersion is applied. 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 to third embodiments described above. is there. In addition, when drying is performed in a state in which the porous resin to which the aluminum-based powder dispersion is applied and the resin sheet to which the aluminum-based powder dispersion is applied are in contact, powder binding that forms the base of aluminum-based porous body Since the body and the precursor layered body are joined and integrated, continuity between the aluminum-based porous body skeleton obtained after heating and the layered body is high. However, after separately drying the porous resin and the resin sheet to which the dispersion is applied, the second embodiment is changed so that the porous resin is placed on the precursor layered body on the resin sheet and charged in the heating step. Also good. Alternatively, one of the porous resin coated with the dispersion and the resin sheet may be dried in advance, and the porous resin may be placed on the resin sheet 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 and resin sheet with the aluminum-based powder adhering to the surface is heated (heating step), and the porous resin and resin sheet are burned off by thermal decomposition. , Advance fusion of powder. Since the powdery binder and the precursor layered body which are the origin of the aluminum based porous body are heated in a state where they are in contact with or integrated with each other, the formed aluminum based porous body and the layered body are well joined by metal bonding. Be done. Therefore, the aluminum-based porous body and the layered body are integrally formed.

  The porous resin can be burnt off generally at about 400 to 550 ° C., and resin sheets and organic components such as adhesives and binders can also be burnt out by this heating as well. 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 the temperature at which the aluminum-based powder is fused without setting the temperature for thermally decomposing the porous resin, it is possible to proceed the thermal decomposition of the porous resin.

  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 skeleton of the aluminum-based porous body and the 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 and layered body formed by bonded particles. The heating temperature preferably does not exceed 100 ° C. or more above the melting point or liquidus temperature.

In order to prevent the oxidation of the aluminum-based powder, it is appropriate to carry out all heating in a non-oxidative atmosphere. 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 layered body occurs when the aluminum-based powder particles are melted by heating, strictly speaking, the precursor layered body and the porous resin form the thermal decomposition of the porous resin. It does not have to be in contact. However, since the compact made of the aluminum-based powder particles after the porous resin and the binder are burned off has poor adhesion between the particles and is easily broken, the porous resin and the resin sheet are thermally decomposed and the powder is melted. It is a realistic way to heat the precursor to continue the integration.

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.

  Aluminum-based powder particles are integrated to form a porous skeleton and a flat layered body, and at the same time, the skeleton and the layered body are connected, so that they are cooled to solidify the melt (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 layered body and the aluminum-based porous body are integrally formed, and the layered body is integrally formed along the outer periphery of the aluminum-based porous body. The layered body is continuous with the skeleton 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 appropriately set in consideration of physical properties such as material strength.

  Thus, the aluminum-based porous member in which the aluminum-based porous body and the layered body are integrally formed is manufactured. The porosity of the aluminum-based porous body is about 90% to about 98%, and the layered body has a porosity of about 5% to about 90%. The skeleton of the aluminum-based porous body may include voids generated by thermal decomposition of the porous resin. Since the skeleton and the layered body of the aluminum-based porous body are produced from the same aluminum-based powder binder, they have the same composition as the raw material aluminum-based powder.

  A layered body is provided not by adhesion through an organic binder or the like but by integral formation with an aluminum-based porous body, and therefore, a component (heat residue such as carbon, carbide, oxide, etc. that inhibits joining in brazing joint Is preferred in that it has a low content of Also, the surface of the layered body is a smooth surface that is easy to bring into close contact with the surface to be bonded. 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 means, 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)
The aluminum-based porous member in which the layered body is integrated is assembled in a state in which the brazing composition is present between the to-be-joined surfaces such as a plate and a tube and the layered body so as to be in close contact with each other. It is joined to a to-be-joined surface by heating to application temperature. 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.

  Since the configuration of the aluminum-based porous member is advantageous in terms of the protection of the porous body and the ease of handling, it can also be used in applications not used for bonding. The above advantages can also be obtained using other metallic or non-metallic sheets that can be bonded to aluminum instead of layered bodies.

  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
As a base made of a foamed resin (porous resin) having a three-dimensional network structure, polyurethane foam (trade name: Everlight SF, manufactured by Bridgestone Corp.) 25 mm long, 70 mm wide and 20 mm thick was prepared. 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. Furthermore, a polyurethane resin sheet of 25 mm long, 70 mm wide, and 0.5 mm thick is prepared, and an adhesive for resin is applied to this surface, and one side of the above-mentioned foamed resin (25 mm long × 70 mm wide) The resin sheet was adhered to the foamed resin by bringing the resin composition into contact with each other to cure the adhesive.

  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 foamed resin to which the resin sheet was adhered in the prepared aluminum powder dispersion, it was taken out, and the foamed resin 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 foamed resin will be in the range of 55.0-60.0 g / L. The foamed resin to which the aluminum powder was attached was dried at 80 ° C. for 120 minutes to obtain a precursor of an aluminum porous member.

The dried precursor is placed on a heating plate and placed in a furnace so that the resin sheet is on the lower side, and the heating temperature is 665 ° C. in a reduced pressure atmosphere (vacuum atmosphere) at a pressure of 10 ⁻³ Pa. The melting point of the aluminum powder used: raised to 660.4 ° C.) and heated at 665 ° C. for 210 minutes. After that, cooling was performed while maintaining a vacuum atmosphere, and when the temperature was lowered to 300 ° C. or less, nitrogen gas was introduced and further cooling to room temperature. When the heating plate was taken out of the furnace and confirmed, the porous resin and the resin sheet were burned off, and a skeleton of the aluminum porous body was formed, and a flat layered body was formed from the aluminum powder adhering on the resin sheet The framework of the layered body and the porous aluminum body was a continuous integral body. The thickness of the layered body in the aluminum porous member thus obtained was about 0.5 mm, and the lower surface (the surface without the aluminum porous body) had a smooth surface. When the porosity of the aluminum porous body and the layered body was measured, the porosity of the aluminum porous body was 98%, and the porosity of the layered body was 30%.

Example 2
The following operation was performed using the same foamed resin, resin sheet and aluminum powder dispersion as in Example 1.
After immersing the foamed resin in the aluminum powder dispersion, the foamed resin was taken out and, similarly to Example 1, the foamed resin was squeezed using an apparatus equipped with a squeeze roll to remove excess aluminum powder dispersion. Furthermore, an aluminum powder dispersion is uniformly coated on one surface of a resin sheet using a roll coater, a foamed resin to which aluminum powder adheres is placed thereon, and dried at 80 ° C. for 120 minutes to obtain porous aluminum The precursor of the member was obtained.

  The dried precursor was placed on a heating pan and 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 porous resin and the resin sheet were burned off and a skeleton of the aluminum porous body was formed and attached on the resin sheet. A flat layered body was formed from the aluminum powder. The framework of the layered body and the porous aluminum body was a continuous integral body. The thickness of the layered body in the aluminum porous member thus obtained was about 0.5 mm, and the lower surface (the surface without the aluminum porous body) had a smooth surface. When the porosity of the aluminum porous body and the layered body was measured, the porosity of the aluminum porous body was 98%, and the porosity of the layered body was 10%.

Example 3
The following operation was performed using the same foamed resin, resin sheet and aluminum powder dispersion as in Example 1.
After immersing the foamed resin in the aluminum powder dispersion, it was taken out, and the foamed resin was squeezed using an apparatus equipped with a squeeze roll. At this time, the degree of squeezing was set looser than in Example 1 so as to leave excess aluminum powder dispersion in the foamed resin. When the foamed resin to which the aluminum powder adhered was placed on the resin sheet, the aluminum powder dispersion contained in the foamed resin was deposited in the form of a resin sheet to cover the surface of the resin sheet. While maintaining this state, drying was carried out at 80 ° C. for 120 minutes to obtain a precursor of an aluminum porous member.

  The dried precursor was placed on a heating pan and 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 porous resin and the resin sheet were burned off and a framework of the aluminum porous body was formed, and was deposited on the resin sheet. A flat layered body was formed from the aluminum powder. The framework of the layered body and the porous aluminum body was a continuous integral body. When the porosity of the aluminum porous body and the layered body was measured, the porosity of the aluminum porous body was 98%, and the porosity of the layered body was 25%.

<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.
An aluminum paste brazing material manufactured by Toyo Aluminum Co., Ltd. (Toyal Hyper Blaze (registered trademark), product name: AF524F, using an applicator for the layered body of the aluminum porous member obtained in each of Examples 1 to 3 Was applied to a thickness of 100 .mu.m and dried at 80.degree. C. for about 10 minutes in the air. Thus, the layered body with the brazing material coated on the surface was brought into intimate contact with the aluminum plate prepared as the material to be joined so that no gap was generated. 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 is extremely useful in the market.

1 Aluminum-based porous member P Aluminum-based porous body M Layered body

Claims (10)

An aluminum-based porous body composed of aluminum or an aluminum alloy,
An aluminum-based porous member having the same composition as the aluminum-based porous body, and a layered body integrally formed along the outer periphery of the aluminum-based porous body.   The aluminum-based porous member according to claim 1, wherein the layered body is flat and has an average thickness of 10 μm or more and 1 mm or less.   The aluminum-based porous member according to claim 1 or 2, wherein a shape of the aluminum-based porous body is a rectangular solid.   The porosity of the aluminum-based porous body is 90% or more and 98% or less, and the porosity of the layered body is 5% or more and less than 90%. Aluminum based porous member.   The aluminum-based porous member according to any one of claims 1 to 4, wherein the porosity of the aluminum-based porous body is 92 to 98% in the layered body for bonding to a heat exchanger. The porous resin and the resin sheet are heated by heating a precursor having a porous resin, a resin sheet in contact with the porous resin, and the porous resin and an aluminum-based powder adhering to the surface of the resin sheet. And pyrolyzing the aluminum-based powder to form a framework and a layered body of the aluminum-based porous body,
And cooling the skeleton and the layered body of the aluminum-based porous body generated in the heating step to integrally form the layered body and the skeleton of the aluminum porous body. The method further comprises a preparation step of preparing the precursor, the preparation step comprising
Preparing an aluminum-based powder dispersion in which the aluminum-based powder is dispersed in a dispersion medium;
Bonding the porous resin to the resin sheet;
Applying the aluminum-based powder dispersion to the surfaces of the porous resin and the resin sheet bonded in the bonding step;
The aluminum-based porous member according to claim 6, further comprising a drying step of obtaining the precursor by drying the porous resin to which the aluminum-based powder dispersion has been applied and the resin sheet to remove the dispersion medium. Manufacturing method. The method further comprises a preparation step of preparing the precursor, the preparation step comprising
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;
A second application step of applying the aluminum-based powder dispersion to the surface of the resin sheet;
The porous resin coated with the aluminum-based powder dispersion is placed on the resin sheet coated with the aluminum-based powder dispersion, and the porous resin and the resin sheet are dried to remove the dispersion medium. The manufacturing method of the aluminum-type porous member of Claim 6 which has the drying process which obtains the said precursor by these. The method further comprises a preparation step of preparing the precursor, the preparation step comprising
Preparing an aluminum-based powder dispersion in which the aluminum-based powder is dispersed in a dispersion medium;
Applying the aluminum-based powder dispersion on the surface of the porous resin such that the porous resin contains the aluminum-based powder dispersion in excess;
The porous resin and the resin sheet are placed in a state where the porous resin to which the aluminum-based powder dispersion is applied is placed on the resin sheet and an excess of the aluminum-based powder dispersion is deposited on the resin sheet. A drying step of obtaining the precursor by drying and removing a dispersion medium. The method for producing an aluminum-based porous member according to claim 6.   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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