JP2019119900A - Aluminium-based porous member - Google Patents

Abstract

To provide an aluminum-based porous member which can braze an aluminum-based porous body by simple work while inhibiting corrosion.SOLUTION: There is provided an aluminum-based porous member which has a three-dimensional network structure and comprises an aluminum-based porous body constituted by a skeleton formed with aluminum or an aluminum alloy and a composition for brazing. The composition for brazing comprises a brazing material powder, a flux and an organic binder. The brazing material powder is composed of silicon and a silicon alloy. The composition for brazing is attached to the tip of at least a part of a skeleton constituting the aluminum-based porous body in a small lump form.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an aluminum-based porous member which is mainly composed of an aluminum-based porous body constituted by a skeleton having a three-dimensional network structure and which is easy to work and handle for bonding to an application member.

  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 aluminum members to a heat exchanger, brazing is used, and a liquid or pasty brazing composition is used.

  The brazing composition for joining aluminum or an aluminum alloy is a mixture in which a brazing material metal powder, a binder, a solvent, and a brazing flux are blended. After applying such a composition to the brazed portion, the aluminum-based members to be joined are assembled, and the brazing operation is performed under heating. The following patent documents 1-4 are mentioned as a composition for brazing of such an aluminum-type member.

  Patent Document 1 describes an extruded tube for heat exchangers in which a brazing material composition layer is applied to the outer surface of an aluminum alloy extruded tube, and the brazing material composition contains a brazing material powder, a flux and a binder. ing.

  In Patent Document 2, a paste-like composition for aluminum brazing comprising an alloy powder for brazing, a fluoride flux, a binder (selected from alkyd resin, butyl rubber, petroleum resin and a mixture thereof), and an organic solvent Is described.

  Furthermore, Patent Document 3 describes a paste-like composition for aluminum brazing using an aluminum-containing powder as an alloy powder for brazing, and by controlling the particle diameter of the aluminum-containing powder, dimensional accuracy of the coating film thickness can be obtained. It is proposed to improve and control the occurrence of erosion.

  On the other hand, since the heat transfer efficiency of the member such as the fin or the like changes depending on the structure, the fin structure is variously miniaturized in order to increase the heat transfer efficiency by increasing the contact area with the fluid. Improvements are being made. Under such circumstances, in recent years, the present inventors have developed an aluminum-based porous body as a structural material that can expect high heat exchange efficiency by application to a member that promotes heat conduction, and proposed in Patent Document 4 below. doing.

JP 2007-51787 A Unexamined-Japanese-Patent No. 2001-225185 JP 2007-275898 A International pamphlet WO2015 / 046623

  In the case of producing a multistage heat exchanger composed of fins (for example, corrugated fins), a multi-hole flat tube, a header and the like using the brazing composition described in the above-mentioned Patent Documents 1 to 3, the multi-hole flat The brazing material composition is applied to the tube, assembled and heat treated, and a number of joints are formed by brazing.

  From the viewpoint of complexity in coating and assembly and adhesion of a coating film, in Patent Document 1, a brazing composition is formed in advance on a multi-hole flat tube (extruded tube), whereby a heat exchanger assembly process is performed. Is very simple and can be performed in a short time.

  On the other hand, in products such as heat exchangers, the tube material that forms the heat exchange flow path and the fin material that dissipates heat have a large number of joints that are to be brazed, and such joint formation is dense In the part, defects such as perforation are very likely to occur due to brazing material erosion (erosion) due to excessive silicon diffusion. Erosion is a phenomenon that has become a serious technical issue in joining aluminum-based members, which has recently been reduced in weight, and includes erosion caused by diffusion of the brazing material component (silicon) and erosion caused by the flow of the brazing material. included. Such suppression of erosion requires advanced atmosphere control and temperature control.

  The aluminum porous body developed in recent years is also expected to be used as a member for promoting heat conduction in a heat exchanger or the like instead of the conventional fin. However, since the porous aluminum body has a fine structure, the technical difficulty of brazing is higher than that of a general-purpose plate fin material. In addition, it is necessary to take care to prevent damage in handling, and handling at the time of brazing is difficult.

  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 an aluminum heat exchanger and the like.

  As a result of various investigations on each component constituting the brazing composition and its material form, the present inventors have identified a bonding form capable of suppressing erosion, and made the brazing function for bonding into an aluminum-based porous body. It came to the integrated configuration to give.

  According to one aspect of the present invention, the aluminum-based porous member has a three-dimensional network structure, and an aluminum-based porous body constituted by a skeleton formed of aluminum or an aluminum alloy, a brazing material powder, and a flux And a brazing composition containing an organic binder, wherein the brazing composition is small-mass attached to the tip of at least a part of the skeleton constituting the aluminum-based porous body, The brazing material powder is composed of silicon or a silicon alloy.

  The brazing filler metal powder preferably has a silicon content of 95% by mass or more, and an average particle diameter of 34 μm or less can suitably perform brazing while suppressing erosion. When the brazing composition further contains an aluminum powder, the reaction activity of silicon can be properly adjusted.

  Further, according to another aspect of the present invention, in the aluminum-based porous member, a brazing composition composed of a flux, a silicon powder, an aluminum powder and an organic binder constitutes an aluminum-based porous body having a three-dimensional structure. It is fixed to at least a part of the tip of the skeleton.

  The organic binder may contain an acrylic resin, and it is advantageous for attachment of the brazing composition that the variation in the position of the tip of the skeleton constituting the aluminum porous body is within the range of 300 μm or less from the surface. The shape of the aluminum-based porous body is highly versatile if it is a rectangular solid.

  Further, according to one aspect of the present invention, the method for producing an aluminum-based porous member is provided with an aluminum-based porous body having a three-dimensional network structure and configured by a skeleton formed of aluminum or an aluminum alloy. A brazing material powder composed of silicon or a silicon alloy, a flux, and a brazing composition containing an organic binder in at least a part of at least a part of the tip of the skeleton of the aluminum-based porous body Attached.

  A brazing filler metal composition for coating containing the brazing filler metal powder, the flux, the organic binder and a solvent is prepared, and the brazing filler metal composition for coating is applied to the tip of the skeleton of the aluminum-based porous body, and the coating is performed. By drying the brazing composition to remove the solvent and baking it, the brazing composition is well attached to the tip of the skeleton. Before attaching the brazing composition to the tip of the skeleton, it is preferable to perform correction to reduce the variation from the surface of the tip of the aluminum porous body to 300 μm or less.

  According to the present invention, since the brazing material is disposed only at the framework tip of the aluminum porous body, which serves as the joining point of the material to be joined (aluminum plate or aluminum multi-hole flat tube), an appropriate amount of brazing material is used Excessive silicon action can be avoided, and problems due to erosion such as dimensional change, disappearance or melting of the skeleton tip of the porous body, etc. can be prevented from occurring. The assembly process at the time of brazing becomes simple and work load can be reduced, and at the same time, the brazing composition for the framework tip acts as a protection to reduce breakage during handling of the porous body, and the manufacturing cost It also contributes to the reduction of

The captured image which shows an example of an aluminum-type porous body. A photography picture showing one embodiment of an aluminum system porous member concerning the present invention. It is a graph for evaluating the dispersion | variation in the frame | skeleton tip of an aluminum porous body. It is the image which detected the frame | skeleton front-end | tip in the surface of the aluminum porous body before and behind correction | amendment, (a) shows before pressure correction processing, (b) shows after pressure correction processing. They are a picked-up image (a) of the joined part of the aluminum porous body and to-be-joined material in sample A1 of an Example, and a partially expanded image (b) of the joined part in a picked-up image (a).

  The paste-like brazing material is a useful bonding material that can place a brazing material at any point to form a bond. However, in the production of the heat exchanger, there is a process of incorporating the flat tube and the fin material in multiple layers in multiple stages, and the complexity of repeating the process of applying the brazing material and assembling the plurality of members and Time and effort is a problem for mass production. 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 (see the above-mentioned Patent Document 4) that has already been proposed. However, brazing of aluminum-based porous bodies is more technically difficult than conventional 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.

  The brazing of the aluminum-based porous body was tried using various brazing materials, and the composition of the brazing material metal and the relationship between the morphology of the brazing material and the bondability / erosion were examined. As a result, an appropriate amount of brazing material is disposed only at the framework tip of the aluminum porous body, which is a contact point with the material to be joined, and a technical method that enables formation of good brazing and suppression of erosion. Found out. The aluminum-based porous member in the present invention has a brazing composition which is attached in a small mass at the tip of the skeleton in the joined portion of the aluminum-based porous body. That is, a small amount of brazing composition is fixed to the tip of the skeleton, like a matching head drug. The brazing composition contains a brazing material powder, an organic binder and a flux, and is prepared into a paste-like coating composition using a solvent in order to be fixed to the skeleton tip. The coating composition is applied to the skeleton tip, solidified by drying and baking, and fixed to the skeleton tip as a brazing composition. The aluminum-based porous member thus obtained is assembled to a member to be joined such that the brazing composition at the tip of the framework is in contact with the surface to be joined, and heated to the brazing temperature in this state to obtain an organic binder Is decomposed and burned off, the brazing material powder is melted, and the molten brazing material acts on the to-be-joined surface from which the oxide layer has been removed by the flux, and the skeleton tip and the to-be-joined surface are joined.

  It is worth noting that in the present invention, the brazing material powder used for the brazing composition is configured based on knowledge different from conventional brazing knowledge. Conventionally, in order to prevent erosion, a brazing composition is formed using a brazing material powder of an aluminum alloy composition having a low silicon concentration so as to control the reaction activity of silicon and aluminum. However, unlike this, as the brazing material powder in the present invention, silicon powder or silicon alloy powder having a high silicon concentration is preferably used. If the silicon concentration of the brazing material powder at the tip of the skeleton is low, the reaction itself between the brazing material powder and the surface to be joined does not easily proceed, so a brazing material powder having a high silicon concentration is used. However, since silicon essentially has a high activity that easily causes erosion, the erosion is suppressed by using an appropriate amount of silicon acting per unit area of the surface to be joined. Below, the composition for brazing is demonstrated.

<Composition for brazing and brazing composition for coating>
The brazing composition is fixed to the tip of the framework constituting the aluminum-based porous body to constitute the aluminum-based porous member of the present invention, and the brazing composition comprises the brazing material powder, the flux and the organic binder. contains. A brazing composition for coating is used to fix the brazing composition to the framework tip. The brazing filler metal composition is obtained by uniformly mixing the components of the brazing composition with an organic solvent to prepare a paste-like mixture. The small mass brazing composition is fixed to the skeleton tip by applying the brazing filler metal composition to the tip of the skeleton, drying to remove the solvent, and solidifying the organic binder by baking. Baking can be carried out generally by heating at about 100 to 200 ° C., and the solvent can be removed during this heating. The paste-like brazing filler metal composition has good dispersibility and coatability, and is suitable for fixing the required amount of the brazing composition in any position. Therefore, the brazing filler metal powder can be disposed at any position, and the adhesion between the skeleton of the aluminum porous body and the brazing filler metal powder can be imparted. Since the brazing composition may be in the brazed portion of the aluminum-based porous body, the brazing composition for coating is at least a tip of a part of the skeleton constituting the aluminum-based porous body, that is, It may be applied to the tip of the portion to be brazed and joined. In addition, since the brazing and joining of aluminum-based members involves heating at a high temperature that can decompose and burn off organic substances, the organic binder is burned out in the temperature raising process for brazing, and the brazing material powder melts at the brazing temperature Work with the surface to be bonded. The composition of the molten brazing material changes to an Al-Si eutectic composition on the joining surface, and the joining material and the aluminum-based porous body are joined.

<Composition and particle size of brazing material powder>
The brazing filler metal powder having a composition containing a high concentration of silicon is used so that the brazing filler metal powder in the small block composition fixed to the tip of the skeleton can exhibit a reaction activity to the bonding surface. Specifically, the brazing material powder is preferably a powder of metallic silicon or silicon alloy, and preferably has a composition in which the content of silicon is 95% by mass or more, more preferably the content of silicon is 98% or more . The use of such silicon or silicon alloys allows good brazing, whereas low silicon content makes bonding difficult. When using a silicon alloy powder, any component may be alloyed with silicon. Specifically, silicon-aluminum alloy, silicon-zinc alloy, silicon-aluminium-zinc alloy, silicon-magnesium alloy, silicon-aluminium-magnesium alloy, silicon-copper alloy, silicon-aluminium-copper alloy, silicon-aluminium- An alloy such as a zinc alloy can be exemplified. Two or more of the powders of these alloys may be used in combination.

  In order to prevent the occurrence of erosion due to the intrinsic activity of silicon, the brazing filler metal composition is designed such that the reaction activity as the brazing composition is appropriately controlled. Since the reaction activity as the brazing composition is controlled by the amount of silicon (that is, the distribution of silicon and the concentration of silicon) acting per unit area of the surface to be joined, the particle size and blending ratio of the brazing material powder (brazing material The proportion of the powder in the composition can be adjusted, as well as the fixed amount of the brazing composition. In particular, the particle size of the brazing material powder greatly affects the occurrence of erosion and the brazability. Therefore, using the brazing composition for coating prepared in the appropriate range, the brazing composition for coating is applied to the skeleton tip at an appropriate application amount. Thereby, the brazing composition disposed at the framework tip can react with appropriately controlled activity. By arranging the brazing material only in the vicinity of the contact point between the skeleton and the bonding surface, excessive silicon diffusion can be prevented.

It is easily understood from the Al-Si phase diagram that, even if the brazing material has a composition with a small driving force of erosion, if a large amount of liquid phase is generated, the amount of silicon to be transferred between the phases is consequently increased. Ru. From this, it is preferable to use a brazing filler metal powder having a small particle diameter, specifically, a brazing filler metal powder having an average particle diameter of about 34 μm or less. The brazing filler metal powder to be used preferably has an average particle diameter of 2 μm or more and 25 μm or less, more preferably an average particle diameter of 2 μm or more and 20 μm or less. Thereby, erosion suppression and junction formation can be performed in a well-balanced manner. The smaller the particle size of the brazing material powder, the more the erosion can be suppressed and the dispersibility when prepared into a paste-like brazing material composition can be maintained well, but if less than 2 μm, the bonding property as a brazing material There is a high possibility of the occurrence of junction failure due to the reduction. On the other hand, use of a brazing filler metal powder with a large particle size improves bondability and facilitates handling of the powder, but using a powder exceeding 50 μm causes melting or disappearance of the aluminum-based framework at the joint due to erosion. Is more likely to occur. Furthermore, separation of particles in the paste is also likely to occur, making uniform application difficult.
The average particle size of the powder is represented by the median diameter (D ₅₀ ). The median diameter is a particle size at which the cumulative distribution becomes 50% by volume, and can be measured by the laser analysis method defined in 8825 of the Japanese Industrial Standard (JIS), and a laser diffraction scattering microtrack particle size distribution analyzer etc. It can be determined based on the particle size distribution measured using.

  The amount of the brazing material powder used is preferably such that the proportion of silicon contained in the brazing composition (that is, the non-volatile component of the brazing composition for coating) is about 36 to 82% by mass, about 45 to 75% by mass It is preferable that The blending ratio is preferably such that the ratio of silicon, flux and organic binder is 20 to 60 parts by mass of silicon, 10 to 25 parts by mass of flux, and 3 to 10 parts by mass of organic binder. When using a silicon alloy powder as the brazing material powder, the amount used may be converted from the ratio of silicon based on the alloy composition of the brazing material powder. Although carbon remaining at the time of burnout of the organic binder can be an inhibiting factor for brazing, in the above-described formulation, the amount of carbon remaining from the organic binder is relatively small, and good brazing is possible.

  When the material to be joined is a thick product or a material having a large heat capacity, the time for maintaining a high temperature at the time of brazing tends to be long. In a situation where such erosion tends to occur, it is effective to reduce or adjust the reaction activity using a mixed powder in which a part of the brazing material powder is replaced with an aluminum powder. This is also effective when using a brazing composition in a system where temperature control is difficult. In such adjustment of reaction activity, the ratio of substitution by aluminum powder is preferably about 10 to 50% by mass of the brazing filler metal powder, and if it is less than this range, the effect of adjusting reaction activity is hard to be realized. If the range is exceeded, there is a risk that the brazed joint will fail. It is not necessary to limit the particle size of the aluminum powder as in the case of the silicon powder, but the average particle size (median diameter) is preferably about 15 μm or less, more preferably 1 in consideration of the dispersibility in the composition. It is preferable that the thickness is not less than 0 μm and not more than 10 μm.

<Flux>
The flux incorporated into the brazing composition is used to remove the oxide film on the surface to be joined. Although chloride-based and fluoride-based fluxes have been widely put to practical use, in the present invention, non-corrosive fluxes that can omit the cleaning step are preferable. For example, fluorides such as potassium fluoroaluminate, potassium fluoride, aluminum fluoride, lithium fluoride, sodium fluoride, potassium fluoroaluminium-cesium complex, cesium fluoroaluminate, potassium fluorozincate, cesium fluorozincate, etc. Compounds are mentioned. At least one of these fluxes can be selected and used, and a plurality of fluxes may be used in combination. Examples of commercially available fluxes include "Nocolok Flux (potassium fluoroaluminate)" and "Nocolok Cs Flux (cesium-based flux)" manufactured by Solvay. In addition, "Nocolok Sil Flux (mixture of potassium fluoroaluminate and metal silicon powder)" manufactured by Solvay, which is commercially available as a mixture of silicon powder and flux, can also be used. The flux may contain zinc, copper or the like for the purpose of corrosion resistance. Moreover, in order to join the aluminum material containing magnesium, brazing property can also be improved by using Cs (cesium) flux etc.

  When the amount of the flux is 30 to 60 parts by mass with respect to 100 parts by mass of silicon of the brazing material powder, it is suitable for removing the oxide film on the surface to be joined. Therefore, when using silicon powder, a flux is mix | blended based on said ratio, and when using silicon alloy powder, what is necessary is just to convert compounding quantity from the said ratio based on the alloy composition.

<Organic binder>
The organic binder is not particularly limited as long as it can bond a metal, and any organic binder can be used. Although the adhesion can be enhanced by selecting a polymer having a large molecular weight, there is a tendency that the carbon residue after the heating and burning is increased. An organic binder may be appropriately selected and used in consideration of the mass of the brazing material powder and the flux to be blended, and the viscosity at the time of paste preparation. It is preferable to have the uniformity of the coating film and the adhesion to aluminum. From the viewpoint of reducing the amount of components that inhibit brazing (components that generate residues such as carbon, carbide, oxide, etc.), it is preferable that the amount of residues due to thermal decomposition during brazing be small. Since brazing is performed at 580 ° C. to 620 ° C., it is preferable that the organic components be sufficiently pyrolyzed by 550 ° C. Specifically, the weight loss at 550 ° C. is preferably 80% or more, more preferably 90% or more, and still more preferably 95% or more.

  Organic binders suitable for the above points include various polymers, and examples thereof include acrylic resin, methacrylic resin, urethane resin, glyoxal resin, phenol resin, butadiene resin latex and the like. Among them, (meth) acrylic acid polymer, (meth) acrylic acid ester polymer, copolymer of (meth) acrylic acid and (meth) acrylic acid ester, polystyrene, styrene-(meth) acrylic acid ester copolymer It is preferable to use (meth) acrylic resin such as organic matter. Among these organic binders, those having a negatively charged polar group are particularly preferred. Since the surface of aluminum is positively charged, the binder having a polar group of negative charge can improve adhesion by acting electrically.

<Additive for paste preparation>
In the present invention, when preparing a paste-like brazing filler metal composition using the above-mentioned brazing filler metal powder, flux and organic binder, if necessary, a thickener for the purpose of viscosity control, brazing filler You may mix | blend the surface treatment agent (for example, silane coupling agent etc.) for improving the adhesiveness of a powder and an organic binder, the leveling agent for suppressing liquid dripping, the dispersing agent of brazing material powder, etc. Although these additives function effectively in the paste state, they may suppress the melting of the brazing material powder and the reaction between the brazing material and aluminum at the time of brazing. Therefore, it is practically preferable that the total amount of these additions be 0.1 mass% to 5 mass% with respect to the brazing composition.

<Organic solvent>
An organic solvent is used when mixing the said component and preparing a paste-form brazing-material composition for application. The organic solvent may be any one that can be adjusted to an appropriate viscosity by diluting the organic binder. Specifically, polar solvents such as alcohols and ketones, aromatic hydrocarbons, aliphatic hydrocarbons and the like can be used. As practical solvents, for example, 3-methoxybutyl acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, butyl acetate, n-propyl acetate, propylene glycol diacetate, propylene glycol n-propyl ether And dipropylene glycol n-propyl ether.

  The paste-like brazing filler metal composition for viscosity-adjusted application is applied to the framework tip of the aluminum porous body and dried (removed from the solvent) and baked to braze the framework tip of the aluminum-based porous body An aluminum-based porous member is obtained, in which small chunks of the composition are fixed.

  Since the aluminum-based porous member of the present invention is a porous body in which the brazing material is fixed to the bonding point with the surface to be joined, it is possible to greatly simplify the complicated steps of coating and assembling. The organic binder contained in the brazing material composition imparts adhesion to the surface of the brazing material powder at the tip of the skeleton and, at the same time, is easily thermally decomposed in the heating process at the time of brazing to adversely affect the brazing. I will not give. Therefore, since a proper amount of brazing material and flux can be supplied to the area to be brazed, good bonding can be formed. In terms of cost, the use of a brazing material powder having a particle size larger than the level of the fine powder which increases the production cost makes it possible to keep the material cost low, which is industrially preferable. Therefore, when manufacturing a heat exchanger using the aluminum-based porous member of the present invention in place of a conventional fin, the work is completed in a short time without performing the complicated work for applying the brazing material. can do. Assembly to a multi-hole pipe, a header pipe, etc. is also easier than before.

  Hereinafter, preparation of the aluminum-based porous member and bonding using the same will be described in detail. In addition, although the aluminum-type porous member can obtain the thing of the preferable property excellent for heat conduction promotion according to the preparation described below, this invention makes the brazing joining of the aluminum-type porous body simple. Basically, aluminum-based porous materials that can be obtained from the market may be used appropriately. In addition, regarding the application and deformation of the aluminum-based porous member, when the metal composition and flux of the brazing material powder are changed to those suitable for brazing to metals other than aluminum, the aluminum-based porous member can be made into various metal members. It can be applied to bonding. Furthermore, the configuration of the aluminum-based porous member may be applied as it is to applications not used for bonding.

(Aluminum-based porous body)
In the present invention, it is preferable that the aluminum-based porous body is a porous body having a skeleton of a three-dimensional network structure made of aluminum or aluminum alloy and in which pores (communication holes) communicating three-dimensionally are formed. It can be used. The shape of the aluminum-based porous body may be appropriately changed according to the form of the brazing part. The rectangular parallelepiped aluminum-based porous body is highly versatile. Depending on the application, any aluminum-based porous body can be selected to carry out fixing of the brazing composition and brazing to the surface to be joined. The porosity of the aluminum-based porous body is also not particularly limited, and a porous body having an appropriate porosity and pore size may be selected and used as needed, and the porosity is generally about 80 to 98%, An aluminum porous body having a pore diameter of about 30 to 4000 μm can be used. When used as a fin material of a heat exchanger, it has a porosity of about 92 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. 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.

(Method of manufacturing aluminum-based porous body)
There is no restriction | limiting in particular in the manufacturing method of an aluminum-type porous body, What is necessary is just to use the aluminum-type porous body of the property suitable for a use irrespective of the manufacturing method. When the aluminum-based porous body is prepared at hand, it can be prepared 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. The molten aluminum (or aluminum alloy) wets and spreads on the surface layer of the particles and reacts to form the communicated aluminum (or aluminum alloy). By cooling this, aluminum (or an aluminum alloy) solidifies in a state of maintaining a three-dimensional structure to form a skeleton, and an aluminum-based porous body is obtained.

  As a method of adhering the aluminum-based powder to the surface of the porous resin, electroplating, dry method, wet method and the like can be mentioned, and any method may be used. The dry method is a method of imparting adhesiveness to the surface of the porous resin to adhere the aluminum-based powder, applying a solution of an adhesive solution or a resin having adhesiveness to the surface of the porous resin, drying and adhering Add gender. The porous resin is shaken in the aluminum-based powder, or the aluminum-based powder is sprayed on the porous resin to adhere the powder. Examples of the pressure-sensitive adhesive include acrylic pressure-sensitive adhesives and rubber-based pressure-sensitive adhesives. Examples of the adhesive resin include, but are not limited to, phenol resins, epoxy resins, and furan resins. You may use it by selecting from the available ones. As the solvent constituting the pressure-sensitive adhesive solution and the adhesive resin solution, a solvent which can dissolve these and has high volatility may be used.

  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. 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)
Since the aluminum-based powder is a powder that forms the framework of the aluminum-based porous body, its composition takes into consideration the thermal conductivity, specific gravity, strength (hardness, brittleness, spreadability), etc. required of the aluminum-based porous body. Are selected from pure aluminum and aluminum alloys. 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. An aluminum alloy pre-alloyed by compounding alloying components such as copper, manganese, magnesium and silicon is useful for improving the strength of the resulting aluminum-based porous body, while having a thermal conductivity of only aluminum It is lower than in the case of taste composition. Therefore, the content of the alloying component may be adjusted 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. Commercially available aluminum powder products may be appropriately selected and used, and examples of commercially available aluminum powder products include 25E and 35C (all of which are product names) manufactured by Eka Granular Co., Ltd. and spray aluminum powders manufactured by Minalco Co., Ltd. Examples include # 300A, # 500A, and # 600F (all are product names).

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 also the median diameter (D ₅₀ ).

(Porous resin with communication holes (foamed resin))
The porous resin (hereinafter, sometimes simply referred to as “foamed resin” or “substrate”) is a substrate that serves as a mold for forming the skeleton of the aluminum-based porous body. Therefore, a porous resin having a three-dimensional network structure is used, which has a skeleton linked in a three-dimensional shape, and pores (communication holes) linked in a three-dimensional shape 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 98% (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.

The porosity of the urethane foam is calculated from the density of the urethane foam calculated based on the measurement of the size and weight of the urethane foam, as in the porosity of the aluminum-based porous body described above. The true density is 1.3 g / cm ³ .

(Method of adhering aluminum-based powder to porous resin surface)
As described above, the aluminum-based powder can be attached to the porous resin surface by using an electroplating method, a dry method, a wet method or the like. In the dry method and the wet method, a pressure-sensitive adhesive that imparts adhesiveness to the porous resin surface and a binder that enhances the adhesion of the aluminum-based powder are used. Furthermore, it is preferable to add a component that suppresses the progress of corrosion of the powder surface, and a component that contributes to sintering promotion of the powder at the time of heating to form a skeleton of the aluminum-based porous body. In addition, a dispersion stabilizer of an aluminum-based powder, an antifoaming agent which suppresses bubbles generated at the time of stirring, and the like may be added.

  In the wet method, there is 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. The aluminum-based powder dispersion used in the wet method is described below.

(Aluminum-based powder dispersion)
As the dispersion medium for the aluminum-based powder dispersion, water or a liquid having volatility such as 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. The stability of the dispersion can be enhanced by blending a dispersant as required.

  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 compounds, epoxy compounds such as polyoxyethylene alkylphenol, or phosphoric acid esters obtained by esterifying acrylic compounds and phosphoric acid are preferable in terms of reactivity at high temperatures, and have about 10 to 18 carbon atoms. Aliphatic phosphate monoesters are more preferred. 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.

  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. Therefore, the thickness of the skeleton is preferably about 50 to 500 μm, and the amount of adhesion to the porous resin is about 10 to 200 μm It is suitable. From this viewpoint, the viscosity of the dispersion is preferably about 50 Pa · s or more and about 500 Pa · s or less at 25 ° C. (value at 50 min ⁻¹ ). The viscosity can be measured using a viscometer. For example, using a viscometer manufactured by Toki Sangyo Co., Ltd. (product name: TVB10 type), the twist angle of the two slit disks by viscosity torque Can be detected and this value can be converted to viscosity.

(Adhesion of aluminum powder)
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, in the case where the excess dispersion liquid remains in the pores of the porous resin pulled up from the dispersion liquid, it may be discharged by pressing using a squeeze roll or the like. The amount of the aluminum-based powder adhering to the porous resin surface can be adjusted depending on the degree of squeezing, and by performing a certain squeezing step, it is also possible to suppress the variation in the amount of adhesion.

  Drying of the porous resin may be with or without 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 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.

(Pyrolytic decomposition of porous resin and framework formation of aluminum-based porous body)
The porous resin to which the aluminum-based powder obtained by drying adheres is heated, whereby the porous resin is burned off by thermal decomposition. The heating temperature for burning out the porous resin may be appropriately set according to the composition of the used porous resin, and it can be burned out generally at about 400 to 550 ° C. Organic components, such as adhesives and binders, can likewise be burnt out by this heating. 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, the heat treatment may be performed 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). In particular, in the case of bonding aluminum-based powder particles by sintering, it is important to prevent oxidation in order to advance sintering by utilizing the loss of the oxide film due to the action of the surfactant.

  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 order to impart strength to the skeleton of the aluminum-based porous body, heating at a higher temperature is performed to bond the powder particles together by fusion.

  In the bonding by fusion, powder particles are melted and integrated by heating at a melting point of aluminum (660.4 ° C.) or a liquidus temperature of an aluminum alloy and then cooled, and the particles are bonded by cooling and solidification. 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 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. Allow the particles to bond together. 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.

  The aluminum-based powder particles are integrated to form a skeleton of the porous body, which is cooled to a temperature lower than the melting point (or liquidus temperature), generally to room temperature (about 1 to 30 ° C.). The aluminum (or aluminum alloy) thermally expanded during heating shrinks by cooling, and the skeleton shape is fixed while maintaining the shape along the three-dimensional network structure of the porous resin, and an aluminum-based porous body is obtained. (See, for example, the picture in FIG. 1). Inside the skeleton, voids resulting from the porous resin may be present. 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.

<Pretreatment of aluminum-based porous body>
The aluminum-based porous body may be cut into a shape and a size suitable for brazing and bonding, if necessary, before applying the brazing filler metal composition for application. The cutting process of the aluminum-based porous body may be appropriately selected from the techniques generally used for cutting materials, and may be applied, for example, using a cutting technique such as electric discharge machining, laser processing, wire saw, etc. It can be easily processed into an aluminum-based porous body having a desired shape and size. Electrical discharge machining is superior in machining precision.

  The frame constituting the aluminum-based porous body has its end interrupted in the surface layer of the porous body and has a tip, and the brazing material composition for coating is applied to the tip. In the aluminum-based porous body subjected to the cutting process, the skeleton ends often become uneven. In addition, irregularities due to skeletal defects of the porous resin used as a raw material and irregularities due to breakage may also occur. Such irregularities in the framework end of the aluminum-based porous body are likely to cause failure in the application of the brazing filler metal composition, so variations in the position of the tip of the framework in the portion to be brazed are 300 μm or less from the surface Preferably, the position of the tip is aligned with a predetermined surface (corresponding to the surface to be joined) so as to be preferably 200 μm or less, more preferably 100 μm or less. The tip position of the skeleton can be aligned by softening or melting the end of the relatively long elongated skeleton and bending or shortening the end. Such end treatment can be easily carried out using a heating plate having a surface shape corresponding to the surface to be joined, and the heating plate is brought into contact with the surface layer portion of the porous body to elongate relatively long. The skeletal ends are heated to soften or melt. By lightly loading the heating plate and approaching the tip position of the relatively short skeletal end, the long skeletal end is bent or turned into a liquid ball, and the tip position is adjusted. Alternatively, the relatively long skeletal end may be heated and melted by laser light irradiation. When aligned by melting of the skeletal ends, the truncated skeletal ends have rounded and fatened tips. The frame tip thus bent or shortened and aligned by softening or melting is easy to apply the brazing filler metal composition and can form a firm joint in brazing joint.

  In the manufactured aluminum-based porous body, distortion may occur such that the outer surface is corrugated due to shrinkage upon cooling. In such a case, the shape can be adjusted by cutting, but the end positions of the skeleton may be aligned by the above-described end treatment. In addition, if the distortion of the shape is overall and the degree of distortion is slight, correction may be performed without heating by sandwiching the aluminum-based porous body with a plate and applying a pressing force. The position of the tip can be aligned so that the variation in the tip position of the skeleton is within the range of 300 μm or less from the surface. In this case, it is preferable to use a jig such as a spacer to limit the application of the pressing force so that the porous body is not damaged by excessive pressing. It is effective to press and rectify the aluminum porous body to align the tip of the skeleton before the brazing composition is attached, in order to increase the bonding rate. Alternatively, when applying and baking the aluminum-based porous member to a member to be joined and fixing it, it is also possible to use the applied pressing force.

<Baking of brazing composition for coating>
The paste-like brazing filler metal composition for application prepared as described above is applied to the surface portion of the aluminum-based porous body to be brazed and bonded to the tip of the skeleton constituting the aluminum-based porous body. Droplets of brazing material composition adhere. Thereafter, drying and baking are performed to prepare, for example, an aluminum-based porous member as shown in FIG. In FIG. 2, the aluminum-based porous member 1 has a small lump of the brazing composition 3 at the tip of the skeleton 2 constituting the aluminum-based porous body.

  When the brazing filler metal composition for coating applied to the tip of the skeleton is heated and raised to the baking temperature, it is dried by vaporization of the solvent in the temperature rising process, and the organic binder is cured at the baking temperature to solidify the composition. . The baking temperature is a temperature at which the curing reaction of the organic binder proceeds, is appropriately set depending on the organic binder used, and can generally be carried out in a temperature range of about 100 to 300 ° C. By maintaining the baking temperature for about 1 to 30 minutes, the organic binder solidifies sufficiently, and a small lump of brazing composition is fixed to the tip of the skeleton. Upon cooling to room temperature, an aluminum-based porous member having a small mass of brazing composition at the tip of the skeleton is obtained.

(Brazed joint using aluminum based porous member)
The aluminum-based porous member of the present invention having a small mass of the composition for brazing at the tip of the skeleton has the brazing temperature in a state where the composition for brazing is assembled in close contact with the surface to be joined such as a plate or tube. Is bonded to the surface to be joined. If flux is applied in advance to at least one of the small mass of the brazing composition and the surface of the material to be joined (such as an aluminum flat tube or an aluminum plate) before joining, the bond inhibition by the oxide film Can be eliminated, and brazing failure due to insufficient flux or uneven coating can be prevented. The flux can be appropriately selected and used from those conventionally used in aluminum-based brazing, and the fluoride-based flux used in the preparation of the above-described brazing composition for coating may be used. The flux is prepared to a solution of an appropriate concentration using an alcohol solvent or the like, and is applied by spraying or dipping to the joining surface and / or the brazing composition blob of the tip of the porous skeleton. In addition, after the aluminum-based porous member is assembled to the member to be joined, flux may be allowed to permeate between the surfaces to be joined. The flux concentration in the solution is preferably 3% by mass to 10% by mass in view of the uniformity of the coated surface.

  The brazing temperature may be set to a temperature equal to or higher than the liquidus temperature in the metal composition of the brazing material powder, preferably to a temperature at which the difference from the liquidus temperature is within about 10 ° C. Generally, brazing is performed at a heating temperature of about 580 to about 620 ° 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.

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

(Preparation of aluminum porous body)
A polyurethane foam having a length of 200 mm, a width of 200 mm, and a thickness of 25 mm was prepared as a porous resin (foamed resin) substrate having a three-dimensional network structure. The mass of this polyurethane foam was 29.3 g and the volume was 1000 cm ³ , so the porosity (the ratio of the volume of the communicating holes to the total volume) was 97.7%. The number of cells of the urethane foam used was 20 ppi.

  Then, in order to prepare an aluminum powder dispersion (slurry), polyvinyl alcohol (PVA, manufactured by Wako Pure Chemical Industries, Ltd.) as a binder and organic phosphorus compound (2-phosphonobutane-1,2,4 as a surfactant) -Defoamer manufactured by Wako Pure Chemical Industries, Ltd. as a defoamer of tricarboxylic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA), polyvinyl alcohol (Product name: Defoamer L, Content : A mixture of mineral oil, higher fatty acid amide, polyethylene glycol type nonionic surfactant etc. was prepared. An aqueous solution of each of the above-mentioned materials is prepared using pure water, and these aqueous liquids are mixed, and the concentration of each component is: binder: 2.0% by mass, surfactant: 3.0% by mass Defoamer: 600 g of an aqueous solution of 0.25% by mass was prepared. The following preparation operations were performed using this aqueous solution as a dispersing aqueous solution (hereinafter, simply referred to as “dispersing aqueous solution”) for dispersing aluminum powder.

A 99.5% pure aluminum powder having an average particle diameter of 6 μm and a melting point of 660.4 ° C. was prepared as an aluminum powder. The average particle size of the pure aluminum powder is the median diameter (D ₅₀ ) determined from the particle size distribution measured using a laser diffraction scattering microtrack particle size distribution analyzer “MT-3100” (product name, manufactured by Nikkiso Co., Ltd.) . An aluminum powder dispersion was prepared by mixing 1000 g of this aluminum powder and a dispersing aqueous solution in a plastic bottle. At this time, the mixing ratio was adjusted so that the mass ratio of the aluminum powder to the aqueous solution for dispersion was 5: 3, and the mixture was stirred for about 5 hours at a rotation number of 40 revolutions / minute (rpm) using a mix rotor. When the viscosity of the obtained aluminum powder dispersion was measured, it was 110 mPa · s (50 rpm, 25 ° C.). In addition, the viscosity was converted into viscosity from this measurement value, detecting the twist angle of the slit disc of 2 sheets by viscous torque using TVB10 type | mold viscometer made from Toki Sangyo Co., Ltd., etc.

  After immersing the foamed resin (polyurethane foam) prepared above in the prepared aluminum powder dispersion, it is taken out, the foamed resin is squeezed using a device equipped with a pair of squeeze rolls, and excess aluminum adhered to the foamed resin The aqueous dispersion of powder was removed (squeezing step). At this time, the degree of squeezing was adjusted so that the adhesion amount of the aluminum powder to the volume 1 L of the foamed resin was in the range of 55.0 to 60.0 g / L.

  The amount of adhesion of the aluminum powder is determined by measuring the mass of the foamed resin before immersion in the dispersion liquid and after the squeezing step to determine the change in mass, and this is the water of the aluminum powder adhered to the foamed resin Based on the mixing mass ratio (5: 3) of the aluminum powder and the aqueous solution for dispersion as the mass of the dispersion, the mass of the aluminum powder adhering to the foamed resin is calculated, and from this value, the aluminum adhered per 1 L of the foamed resin volume The adhesion amount of powder was determined.

The foamed resin to which aluminum powder adhered was dried at 80 ° C. for 60 minutes (drying step). Next, heating was performed for 210 minutes at 665 ° C. (temperature above the melting point (660.4 ° C.) of the used aluminum powder) in a reduced pressure atmosphere (vacuum atmosphere) at a pressure of 10 ⁻³ Pa (heating step). After that, cooling was performed while maintaining a vacuum atmosphere (cooling step), and when the temperature was lowered to 300 ° C. or less, nitrogen gas was introduced and further cooled to room temperature. Thus, an aluminum porous body was produced, and the porosity of the aluminum porous body calculated from the values of dimension measurement and weight measurement was 96.5%. Preparation and brazing evaluation of an aluminum porous member were performed as follows using the aluminum porous body produced in this way.

(Cutting and correction)
The aluminum porous body was cut into a rectangular shape of 25 mm × 65 mm × 6.6 mm. The cutting was performed by electrical discharge machining so as to prevent the formation of a burr on the framework of the aluminum porous body. After cutting, sandwich the upper and lower surface (surface of dimension 25 mm × 65 mm) of the aluminum porous body with two flat plates made of SUS, press a jig with 6.0 mm height between the flat plates and press it up and down , Corrected the overall slight distortion. The thickness after correction was 6.05 mm. The aluminum porous body obtained in this manner was used for preparation of aluminum porous members in the following samples A1 to A8. Moreover, the dispersion | variation in the skeleton tip in the surface layer part of the upper surface was evaluated about the aluminum porous body before and behind a correction process. The results will be described later

[Samples A1 to A8]
(Preparation of brazing filler metal composition for coating)
Prepare the following raw materials (brazing agent S1 to S5, flux, organic binders Z1 to Z3, solvent, surface treatment agent), mix the raw materials according to the composition described in Table 1, and apply brazing material composition of samples A1 to A8 Prepared.

(raw materials)
Wax material S1: Silicon powder / flux (mass ratio: 2/1) mixture (product name: NOCOLOK® Sil Flux 2: 1 (extra fine grade, gray powder made by SOLVAY), silicon powder D ₅₀ : 2 to 2 6 μm, flux: potassium fluoroaluminate wax material S 2: silicon powder / flux (mass ratio: 2/1) mixture (product name: NOCOLOK® Sil Flux 2: 1 (fine grade), gray powder made by SOLVAY), silicon Powder D ₅₀ : 17.5 μm, Flux: potassium fluoroaluminate Wax material S 3: Silicon powder (Product name: No. 350, Yamaishi Metal Co., Ltd.), D ₅₀ : 25 μm
Braze S4: silicon powder (purity> 99%, particle size <45μm), D _50: 34μm
Wax material S5: Aluminum powder (product name: Ecka 25E, manufactured by ECKA Granules Germany GmbH), D ₅₀ : 6 μm
Flux: potassium fluoroaluminate (product name: NOCOLOK Flux, manufactured by SOLVAY), D ₅₀ : 4 μm
Organic binder Z1: Acrylic resin (Product name: NM-2002-1, made by Fujikura Kasei Co., Ltd.), Mw: 170 × 10 ⁴
Organic binder Z2: Acrylic resin (Product name: KC-1100, manufactured by Kyoeisha Chemical Co., Ltd.), Mw: 13 × 10 ⁴
Organic binder Z3: polyvinyl alcohol, Mw: 150 × 10 ⁴
Surface treatment agent: 3-acryloxypropyl trimethoxysilane (product name: KBM-5103, manufactured by Shin-Etsu Silicone Co., Ltd.)
Terpineol (manufactured by Nippon Scent & Drug Co., Ltd.)

(Coating and baking)
The following operations were performed using each of the paste-like brazing filler metal compositions for samples A1 to A8.

The upper and lower surfaces (surface of 25 mm × 70 mm) of the aluminum porous body are each dipped in the brazing composition for coating, and then placed 250 ° C. in the air with the non-coated surface down and standing up. And baked for 10 minutes. After this, natural cooling was performed to obtain aluminum porous members of samples A1 to A8.
The surface layer portion of the aluminum porous body was observed for each sample, and it was confirmed that small pieces of the brazing composition exhibiting a dark brown derived from silicon powder were fixed to the tip of the skeleton in each case. .

<Evaluation of Adhesion and Strength of Brazing Composition>
The state and adhesion before brazing of the brazing composition after baking were evaluated based on the following criteria. The evaluation results are shown in Table 1.
"A": Even if it rubs with a finger strongly or it strikes, the small block of the tip does not separate.
"B": The small chunk at the tip does not separate even if it is struck, but it peels off when it is strongly rubbed.
"C": The small chunk at the tip peels off easily when struck.

(Brazed)
An aluminum plate (JIS-A1050) having a thickness of 2.0 mm was prepared, cut into a size of 30 mm × 100 mm, and used as a material to be joined in the following operation. In addition, as a flux, a 5% ethanol aqueous solution of potassium fluoride aluminate was prepared.

  In each of the samples A1 to A8, the aluminum porous member is sandwiched from above and below with two members to be joined so that the small pieces of the brazing composition fixed to the tip of the frame contact the members to be joined, The load was fixed from the top with a carbon-made weight so that a crevice might not be generated. Under the present circumstances, in order to prevent that the space | interval of a to-be-joined material between upper and lower shrinks | contracts excessively, the jig | tool made from carbon whose height is 6.0 mm is interposed between to-be-joined materials, and the longitudinal direction of aluminum porous member Arranged at both ends. These were fixed with a stainless steel wire so that the assembled state was maintained, and after the flux solution was sprayed over the entire surface to be joined in contact with the porous body, it was introduced into a brazing furnace.

  The aluminum porous member and the workpiece were heated in a nitrogen atmosphere (oxygen concentration: 20 ppm or less) in a furnace. At this time, the temperature in the furnace was raised from room temperature to 590 ° C. in about 10 minutes, and then held at 590 ° C. (samples A1 to A6) or 595 ° C. (samples A7 and A8) for 3 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.

  When fixation with a wire was removed from the collected matter and visually observed, in any of the samples A1 to A8, the formation of fillets was confirmed in the brazed portion of the frame tip of the aluminum porous body and the material to be joined, No progress was seen. From the observation results, it is inferred that the bonding between the aluminum plate as the bonding material and the aluminum porous body is in a strong state. About the sample A1, the photography image of the joined part of an aluminum porous body and a to-be-joined material is shown to Fig.5 (a). FIG.5 (b) is the image to which a part of junction part in the picked-up image of Fig.5 (a) was expanded. According to FIG. 5, the bonding of the aluminum porous body is well formed by using the silicon powder as the brazing material, and erosion and melting shortening of the skeleton tip are not observed.

  About the aluminum porous member brazed to the to-be-joined material, the dimensional change of aluminum porous body by brazing and evaluation of joint strength were performed as follows. The evaluation results are shown in Table 1.

<Dimensional change due to brazing>
The dimensional change in the thickness direction of the aluminum porous body before and after brazing was evaluated based on the following criteria.
"A": Dimension change less than 0.3 mm (nearly no change)
"B": The dimensional change is 0.3 mm or more and less than 0.7 mm (slight change is seen, but the brazing itself is good)
"C": The dimensional change is 0.7 mm or more, and there may be spots where the skeleton melts and disappears

<Evaluation of joint strength>
For each of the bonded bodies, one of the aluminum plates was fixed, and a weight load of 1 kg was applied to the other, and the bonding state was visually observed. The bonding strength was simply evaluated based on the observation results as follows.
"A": No peeling occurred at any of both bonding interfaces and withstands the weight load "B": A part of the framework of the aluminum porous body peeled from the material to be bonded "C": at the bonding interface Material to be bonded exfoliates and separates, apparently not enough

  From the results shown in Table 1, when using the aluminum porous member coated and baked with the brazing filler metal composition for coating on the framework tip of the aluminum porous body, brazing can be performed by a simple method, and good bonding strength can be obtained. It is understood that it can be joined to an aluminum plate. The brazing composition pre-baked and fixed to the tip of the skeleton has good adhesion to the skeleton and also reduces peeling and breakage of the brazing composition during handling. Therefore, the work of reapplying the brazing material can be eliminated.

  When samples A1 to A4 with different particle sizes of brazing filler metal powder are compared, the adhesion and strength after baking decrease as the particle size increases, and the dimensional change of the aluminum porous body tends to increase. Also, the bonding strength to the aluminum plate is obtained, and the sample A4 having the largest particle size is at a level that causes no problem in practical use. From this, with respect to the particle size of the brazing material powder, one having an average particle size of 34 μm can be suitably used.

  When samples A2, A5 and A6 having different organic binders are compared, samples A2 and A5 using an acrylic resin are more excellent in adhesion and strength of the brazing material than samples A6 using polyvinyl alcohol. An acrylic resin is a binder which is excellent in adhesive strength and thermal decomposition, and has a small residual carbon after pyrolysis. The use of such a thermally decomposable organic binder is suitable as a binder for fixing the brazing material and the aluminum-based porous body, since the use of such a thermally degradable organic binder is a hindrance to brazing.

  Samples A7 and A8 are due to different brazing conditions, and the brazing temperature is 5 ° C. higher than samples A1 to A6. In sample A7 using only silicon powder as the brazing material, dimensional change due to brazing increases. This is considered to be due to the progress of erosion due to the temperature rise. However, in the sample A8 in which the mixing ratio of silicon is reduced by mixing the aluminum powder, the dimensional change is reduced compared to the sample A7, so that the erosion can be alleviated by suppressing the silicon concentration in the composition. It can be said that it is possible.

  Since aluminum generally loses its strength at high temperatures and shrinks when heated, the load may affect the porous aluminum body in brazing under load. There is. However, by arranging the jig as described above, the dimensional change during heating can be regulated, and the aluminum porous body can be prevented from being deformed or damaged by a load.

[Sample B1]
The brazing material composition for coating was prepared by the same composition as the sample A1 except that the organic solvent (terpineol) was increased by the compounding amount without using the organic binder. Using the brazing filler metal composition for application, baking was performed by the same operation as in sample A1 to form an aluminum porous member, and brazing was performed to join the workpiece and the aluminum porous member.
The adhesion and strength of the brazing composition were evaluated after baking, and the dimensional change by brazing and the evaluation of joint strength were similarly performed on the joined body after brazing. As a result, the adhesion and strength of the brazing composition were evaluated as C, and the apparent lack of adhesion caused the brazing material to peel off even with impact or slight rubbing. Moreover, evaluation of the dimensional change by brazing was C, and evaluation of the joint strength was B.

  In sample B1, the adhesion and strength of the brazing composition after baking are apparently insufficient, which is attributable to the absence of the organic binder. The low bonding strength after brazing is also considered to be caused by the fact that the brazing composition does not adhere sufficiently. In addition, the organic binder is also effective in suppressing erosion from the viewpoint that the dimensional change of the aluminum porous body due to brazing increases, and the brazing material powder particles do not act intensively, and the organic binder It is understood that the action is properly distributed.

[Sample B2]
A paste-like brazing composition for application similar to that of sample A1 was prepared. Using a film applicator, the brazing filler metal composition for application is formed on a 30 μm membrane so that it has the same area (28 mm × 68 mm) as the upper and lower surfaces of the aluminum porous body on one side of each of two materials to be joined. The brazing composition was fixed to the surface of the workpiece by applying a thick coating, drying at 80 ° C. for about 10 minutes in the air, and then baking at 250 ° C. for about 10 minutes in the air. The coating amount (including the binder) per unit area of the brazing composition was 21.5 g / m ² .

  The aluminum porous body is sandwiched by using two members to be joined with the surface to which the brazing composition is fixed facing inward, and no gap is generated between the skeleton tip of the aluminum porous body and the member to be joined Thus, it was fixed by applying load from above with a carbon weight. At this time, as in the case of sample A1, a carbon jig having a height of 6.0 mm is interposed between the materials to be joined to prevent the space between the upper and lower materials to be reduced from being excessively reduced. Fixed. After spraying the flux solution on the entire surface of the brazing composition in contact with the porous body, it was introduced into the brazing furnace.

  The aluminum porous body and the workpiece were heated in a nitrogen atmosphere (oxygen concentration: 50 ppm or less) in a furnace. At this time, the temperature in the furnace was raised at 10 ° C./min from room temperature to 590 ° C., and then the temperature was held at 590 ° C. for 3 minutes. Thereafter, the inside of the furnace was rapidly cooled, and the porous aluminum body and the workpiece were recovered from the inside of the furnace which had returned to room temperature.

  The evaluation of the dimensional change due to brazing and the bonding strength was similarly performed for the brazed aluminum porous body and the bonding material. As a result, the evaluation of dimensional change due to brazing was C, and the evaluation of joint strength was C. As a result of visual observation of the bonded portion, a defect occurred in the skeleton of the aluminum porous body, and it was confirmed that there was partial peeling or breakage, or a portion to which the brazing material was not attached at the bonded interface of the material to be bonded. These are due to the progress of erosion (erosion of the brazing material due to diffusion of silicon), and the brazing material powder on the material to be joined acts intensively on the contact portion of the framework tip of the aluminum porous body. it is conceivable that. This sample is in the form in which the brazing composition is applied to the surface to be joined, as in the prior art. From this result, in the conventional application form, the aluminum porous body and the article to be joined are well joined by brazing. It is obvious that it is difficult to do.

[Sample B3]
Two aluminum plates clad with a brazing material of alloy No. A 4045 (Al-10Si) on one side were prepared, and a 5% flux solution was applied to the surface. The upper and lower portions of the aluminum porous body were sandwiched by these aluminum plates and brazing was performed. The same conditions as for sample A1 were applied for heating and use of jigs during brazing. With respect to the joined body obtained after brazing, evaluation of the dimensional change due to brazing and the bonding strength were similarly performed. As a result, the evaluation of dimensional change due to brazing was C, and the evaluation of joint strength was C. The thickness of the aluminum porous body is shrunk by 2.1 to 2.4 mm by brazing, and the dimensional change is considered to be melting by erosion.

[Sample B4]
An aluminum paste brazing material (Toyal Hyper Blaze (registered trademark), product name: AF524F, A4047 / Al-12Si) manufactured by Toyo Aluminum Co., Ltd. was prepared. This paste brazing material contains Al-12Si alloy powder having an average particle size of about 70 μm, and the same operation as Sample 1A is repeated except that this is used instead of the brazing material composition for coating, and aluminum is porous. When the adhesion and strength of the brazing material after baking were evaluated by applying and baking the brazing material to the base body, the evaluation result is C, and the adhesion between the framework tip and the brazing material is insufficient, It peeled when touching the material.
Furthermore, although brazing to a material to be joined was performed in the same manner as in the sample A1, the aluminum porous body and the material to be joined were not joined, and a joined body was not obtained.

The following can be said from samples A1 to A8 and B1 to B4.
First, in the sample B2 by the conventional brazing method and the sample B3 using the clad material by the brazing material (Al-10Si alloy), the occurrence of erosion can not be avoided, the dimensional change is large, and the bonding strength after the brazing It is also extremely low. The cause is considered to be that the amount of silicon is too large. On the other hand, in the aluminum porous members of samples A1 to A8 in which small particles of the brazing filler metal composition for coating are applied and fixed to the tip of the skeleton, the brazing filler metal powder having a high silicon concentration performs bonding without causing the problem of erosion. It can be formed. That is, in the brazing form in which the formation density of bonding is low, the brazing material powder having a high silicon concentration preferably functions, and in the brazing material powder having a low silicon concentration, the formation of bonding itself does not proceed. This point is also understood from the fact that bonding itself is difficult in sample B4 using a commercially available paste paste material of Al-12Si alloy.

  In an aluminum powder and an Al-Si alloy powder containing aluminum as a main component, the thickness of the dense oxide film present on the particle surface is substantially constant (about several nm to about 20 nm) regardless of the particle size. The smaller the ratio, the higher the proportion of the oxide film. For this reason, the powder of the Al-Si alloy in the paste composition loses its function as a brazing material as the particle size becomes smaller, and the handling of the brazing material when preparing the paste becomes difficult. This point is considered to be a cause of the difficulty in forming a bond in sample B4. However, if the concentration of silicon is high, the problems caused by the oxide film as described above are avoided, and the powder having a small particle size works effectively as a brazing material. Therefore, it is possible to avoid the occurrence of erosion due to the non-uniformity of the brazing filler metal component by using a brazing filler metal powder having a high silicon concentration and a relatively small particle diameter.

<Variation evaluation of skeletal tip of surface layer by X-ray CT>
By the following measurement using a microfocus X-ray CT system SMX-160CT (manufactured by Shimadzu Corporation), the dispersion of the skeleton tip in the surface layer portion was evaluated for each of the aluminum porous bodies before and after the pressure correction processing.

  An aluminum porous body as a sample is placed on a column of expanded polystyrene (a material not visible in a CT image), and X-ray scanning is performed while rotating the sample to obtain an X-ray CT image of the aluminum porous body. The The measurement conditions at this time were X-ray tube voltage: 75 kV, brightness (current): 100 mA, detection size: 4 inch, SID: 387.7 mm, SOD: 78 mm, view number: 1200, average number: 8. An area of 10 mm × 10 mm × 3.0 mm was extracted from the obtained X-ray CT image to correct the parallelism (slight inclination of the cut surface) in the image. Parallel to the surface based on the corrected X-ray CT image in order to examine the internal structure on the surface layer (the distance from the surface is in the range of 0.9 mm) on the upper surface (surface of dimension 25 mm × 65 mm) of the sample Cross-sectional images were acquired at a pitch of 30 μm.

  The cross-sectional image of the aluminum porous body thus obtained was subjected to image analysis using an image analysis software "Image J". That is, the cross-sectional image was detected as a binarized image (black and white image), and the area ratio (%) of aluminum occupying each cross section was calculated from the obtained binarized image. The result of showing the relationship between the area ratio of the obtained aluminum and the distance from the surface in a graph is shown in FIG.

  In the sample before the correction processing in FIG. 3, the area ratio of aluminum gradually increases in the region up to 0.3 mm from the surface of the porous body, and the value is almost uniform in the region 0.3 mm or more About 5%). That is, it is understood that the maximum value of the area ratio is about 5%. Therefore, it can be considered that the position of the framework tip of the aluminum porous body is distributed in the range of 0.3 mm (300 μm) from the surface. On the other hand, in the sample after the correction processing in FIG. 3, the range in which the area ratio of aluminum increases is narrowed to a range of about 0.1 mm from the surface. Therefore, it is understood that the pressure distribution on the surface of the porous body can narrow the distribution range of the position of the skeletal tip and align the tips by pressure correction.

  In this manner, based on the cross-sectional image of the aluminum porous body, it is possible to obtain the variation in the position of the tip of the skeleton as a range in which the area ratio of aluminum increases. Moreover, it is also possible to calculate the number of aluminum skeletons by such image analysis. In the sample after the correction processing in FIG. 3, the position of the skeleton tip is distributed in the range of 0.1 mm (100 μm) or less from the surface, and the area ratio of aluminum at a distance of 0.06 mm from the surface is about 4.1. % (That is, 82% of the maximum value). Therefore, for example, under the condition that the brazing filler metal composition for coating can be applied in the range of 0.06 mm (60 μm) or less from the surface of the porous body, the brazing composition is attached to about 80% or more of the skeleton tip of the surface layer portion It is understood that it is possible.

<Effect of pressure correction>
A black ink is applied on a flat plate using a squeegee to form a thin film adjusted to a thickness of 0.1 mm, and the upper surface (surface of dimension 25 mm × 65 mm) of each of the aluminum porous bodies before and after the correction treatment Was pressed against the black ink thin film to adhere the black ink to the tip of the skeleton. Thereafter, the surface to which the black ink was attached was brought into contact with the white paper to obtain a black ink transfer image. The transferred image is shown in FIG. FIG. 4A shows a transferred image of the sample before the correction process, and in the transferred image of the sample after the correction process of FIG. 4B, the transferred black points increase. That is, it is clear that the length of the skeleton can be aligned so that the skeleton tip is positioned on the surface of the porous body by the pressure correction. Therefore, a thin film of the brazing composition for coating is formed in the same manner as the above-described ink thin film, and the bonding surface of the aluminum porous body is pressed against the thin film to adhere and solidify the brazing composition for coating. Small pieces of the brazing composition for the framework tip of the aluminum porous body may be present in the same manner as the transferred image of FIG. The transferred image in FIG. 4 can be considered to correspond to a cross-sectional image (a cross-sectional image with a distance from the surface of 0.1 mm) obtainable based on the above-mentioned X-ray CT image of the aluminum porous body. Therefore, it is also possible to evaluate the dispersion of the skeleton tip of the porous body using the transferred image as shown in FIG.

  It is possible to perform good brazing of the aluminum-based porous body by a simple operation while suppressing erosion, and it is also possible to cope with the shape of the surface to be joined, etc. Becomes possible. Therefore, it is useful to incorporate an aluminum-based porous body as a component such as a heat dissipating fin of a heat exchanger. When applying an aluminum-type porous body to the use which harnessed thermal conductivity, it is very useful in a market as a product which is easy to join and handle.

1 Aluminum-based porous member 2 Frame 3 Brazing composition

Claims (8)

An aluminum-based porous body having a three-dimensional network structure and constituted by a skeleton formed of aluminum or an aluminum alloy;
And a brazing composition containing a brazing material powder, a flux, and an organic binder, wherein the brazing composition is agglomerated at the tip of at least a part of the skeleton of the aluminum-based porous body. An aluminum-based porous member, wherein the brazing material powder is made of silicon or a silicon alloy.   The aluminum-based porous member according to claim 1, wherein the brazing material powder has a silicon content of 95% by mass or more.   The aluminum-based porous member according to claim 1, wherein the brazing filler metal powder has an average particle diameter of 34 μm or less.   The aluminum-based porous member according to any one of claims 1 to 3, wherein the brazing composition further contains an aluminum powder.   An aluminum-based porous member in which a brazing composition composed of a flux, silicon powder, aluminum powder and an organic binder is fixed to at least a part of the tip of a skeleton constituting an aluminum-based porous body having a three-dimensional structure.   The aluminum-based porous member according to any one of claims 1 to 5, wherein the organic binder contains an acrylic resin.   The aluminum-based porous member according to any one of claims 1 to 6, wherein the variation in the position of the tip of the framework constituting the aluminum porous body is within the range of 300 μm or less from the surface.   The shape of the said aluminum-type porous body is a rectangular parallelepiped shape, The aluminum-type porous member as described in any one of Claims 1-7.