JP2019155460A - Brazing material powder, composition for brazing and conjugated body - Google Patents

Abstract

To provide a brazing material powder having both brazability and erosion resistance used for mutual brazing of members prepared by aluminum or the alloy thereof, and to provide a brazing composition including the brazing material powders, and a conjugated body brazed using the brazing composition.SOLUTION: A brazing material powder for mutual brazing of members prepared by aluminum or the alloy thereof includes Al, Cu, Si and Zn, and comprises in mass% based on total mass of the above powder, more than 20.0% but less than 27.0% of Cu, 2.0-10.0% of Si, 3.0-10.0% of Zn, and the balance of Al with inevitable impurities. In the integrated volume distribution of the brazing material powder, a 50% cumulative particle size (D) is 80 μm or more but 200 μm or less, and a 99% cumulative particle size (D) is 400 μm or less. The oxygen concentration of the brazing material powder is 600 ppm or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a brazing material powder, a brazing composition, and a joined body, and more particularly, a brazing material powder for brazing members made of aluminum or an alloy thereof, and a brazing material including the brazing material powder. The present invention relates to a composition and a joined body brazed with the brazing composition.

  2. Description of the Related Art Conventionally, in a heat exchanger, for example, a joined body obtained by brazing (joining) a member made of aluminum or an alloy thereof with a brazing paste (composition for brazing) is used.

  In such heat exchangers, in recent years, the number of pipes has increased, the density of pipes has increased, the pipe shape has become complex, and the like, and thus brazing pastes are required to have better brazing properties.

  On the other hand, in order to reduce the weight and increase the efficiency of the heat exchanger, it is required to reduce the thickness of the pipe.

  However, if a brazing paste with excellent brazeability is used for such thin-walled pipes (specifically, a thickness of 0.6 mm or less), excessive erosion of the pipes will occur, resulting in heat exchangers. There is a defect that reduces the durability of the.

  Therefore, a brazing paste having both brazing and erosion resistance is required. Specifically, 25% by mass of Cu, 4% by mass of Si, 10% by mass of Zn, and the balance of Al. In addition, a brazing material (average particle size 121 μm) containing unavoidable impurities is proposed, and it is proposed to braze an aluminum alloy and a copper alloy with a slurry containing the brazing material and a flux. (For example, refer to Patent Document 1 (Example 25).)

JP 2013-123754 A

  On the other hand, in the heat exchanger, a member formed by brazing (joining) aluminum or an alloy thereof is used in addition to a member obtained by brazing (joining) the above-described aluminum or an alloy thereof and copper or an alloy thereof. There is a case.

  In such a case, when members are joined with the slurry described in Patent Document 1, erosion resistance may not be sufficiently obtained.

  The present invention relates to a brazing material powder having both brazing and erosion resistance in brazing between members made of aluminum or an alloy thereof, a brazing composition containing the brazing material powder, and the brazing material A joined body brazed with the composition.

The present invention [1] is a brazing filler metal powder for brazing members made of aluminum or an alloy thereof, containing Al, Cu, Si and Zn, with respect to the total amount of the brazing filler metal powder. The Cu content ratio is more than 20.0 mass% and less than 27.0 mass%, the Si content ratio is 2.0 mass% or more and 10.0 mass% or less, and the Zn content ratio is 3. 0% by mass or more and 10.0% by mass or less, and the balance is made of Al and inevitable impurities. In the cumulative volume distribution of the brazing filler metal powder, the 50% cumulative particle size (D ₅₀ ) is 80 μm or more and 200 μm or less, A brazing filler metal powder having a 99% cumulative particle diameter (D ₉₉ ) of 400 μm or less and an oxygen concentration of the brazing filler metal powder of 600 ppm or less is included.

  The present invention [2] is a brazing composition comprising a brazing filler metal powder, a Cs—Al—F-based flux, and a binder resin, wherein the brazing filler metal powder is the brazing filler metal powder according to claim 1. Yes, with respect to the total amount of the brazing composition, the content of the brazing filler metal powder is 40 mass% or more and 80 mass% or less, and the content ratio of the Cs-Al-F flux is 10 mass% or more 40 The mass ratio of the binder resin to the total mass of the brazing filler metal powder and the Cs—Al—F flux (binder resin / (brazing filler powder + Cs—Al—F flux)) is 0% by mass or less. 1 / 99.9 or more and 25/75 or less.

  The present invention [3] is the above [2], wherein the brazing composition has any one shape selected from the group consisting of a paste shape, a rod shape, a plate shape, a pipe shape, a linear shape and a ring shape. The brazing composition described in 1. above.

  The present invention [4] is a joined body in which members made of aluminum or an alloy thereof are joined to each other by the brazing composition according to the above [2] or [3], wherein the member has a tubular shape. Or it is a pipe-shaped member, and the end parts of the members are fitted to each other, and in the fitting part by the fitting, the outer diameter of one member is less than the inner diameter of the other member. Yes.

  The present invention [5] includes the joined body according to the above [4], wherein the thickness of any one of the members is 0.45 mm or less.

  In the present invention [6], the thickness of any one of the members is thicker than the thickness of the other member, and the thickness ratio of the thick member to the thin member is 2 or more. The joined body according to the above [4] or [5] is included.

In the brazing filler metal powder and the brazing composition of the present invention, the Al content, Cu content, Si content, and Zn content are adjusted within predetermined ranges, and 50% of the brazing powder. The cumulative particle diameter (D ₅₀ ), 99% cumulative particle diameter (D ₉₉ ), and oxygen concentration are adjusted to predetermined ranges.

  As a result, according to the brazing filler metal powder and the brazing composition of the present invention, it is possible to secure excellent erosion resistance while securing excellent brazing properties in brazing between members made of aluminum or an alloy thereof. Can do.

  Moreover, since the joined body of the present invention is obtained by using the brazing material powder and the brazing composition of the present invention, it is excellent in brazing property and erosion resistance.

FIG. 1 is a schematic perspective view of a cross fin tube type heat exchanger. FIG. 2 is an enlarged view of a heat exchanger joint pipe provided in the heat exchanger of FIG. 1. FIG. 3 is a flowchart showing a method of joining the refrigerant pipe and the connecting pipe, FIG. 3A is a step of preparing the refrigerant pipe and the connecting pipe, and FIG. 3B is a fitting of the refrigerant pipe and the connecting pipe. Steps and FIG. 3C show the steps of disposing the brazing composition in the vicinity of the fitting portion between the refrigerant pipe and the connecting pipe, respectively. FIG. 4 is a schematic view showing erosion (erosion) of the pipe.

  The brazing filler metal powder of the present invention is an Al—Cu—Si—Zn based alloy powder containing aluminum (Al), copper (Cu), silicon (Si) and zinc (Zn) in a predetermined ratio.

  The Al—Cu—Si—Zn alloy is made of aluminum (Al), copper (Cu), silicon (Si), zinc (Zn) and inevitable impurities, and these are obtained by alloying them by a known method. Can do.

  Note that the Al—Cu—Si—Zn-based alloy allows the inclusion of inevitable impurities. The inevitable impurities are impurity components inevitably mixed in the production process of the Al—Cu—Si—Zn alloy, and specifically, iron (Fe), manganese (Mn), magnesium (Mg), chromium ( Cr), tin (Sn), lead (Pb), and the like. The content ratio of these inevitable impurities is in a range that does not affect the properties of the Al—Cu—Si—Zn alloy, specifically, 2.0 mass relative to the total amount of the Al—Cu—Si—Zn alloy. % Or less, preferably 1.20% by mass or less.

  The content ratio of copper (Cu) exceeds 20.0% by mass, preferably 21.0% by mass or more, more preferably 22.0%, based on the total amount of the Al—Cu—Si—Zn alloy. % By mass or more, more preferably 23.0% by mass or more, less than 27.0% by mass, preferably 26.0% by mass or less, more preferably 25.0% by mass or less, more preferably 24 0.0 mass% or less.

  The content ratio of silicon (Si) is 2.0% by mass or more, preferably 2.5% by mass or more, more preferably 3.0% by mass with respect to the total amount of the Al—Cu—Si—Zn-based alloy. % By mass or more, more preferably 4.0% by mass or more, 10.0% by mass or less, preferably 9.0% by mass or less, more preferably 7.0% by mass or less, further preferably 5% or less. 0.0 mass% or less.

  The content ratio of zinc (Zn) is 3.0% by mass or more, preferably 3.5% by mass or more, more preferably 4.0%, based on the total amount of the Al—Cu—Si—Zn alloy. % By mass or more, more preferably 5.0% by mass or more, 10.0% by mass or less, preferably 9.0% by mass or less, more preferably 7.0% by mass or less, more preferably 6% by mass or less. 0.0 mass% or less.

  If the content ratios of Cu, Si and Zn exceed the lower limit, excellent brazing properties can be obtained. Moreover, if the content ratio of Cu, Si and Zn is less than the above upper limit, excellent erosion resistance can be obtained.

  The total amount of aluminum (Al) and inevitable impurities is the balance of copper (Cu), silicon (Si), and zinc (Zn) in the Al—Cu—Si—Zn alloy, and specifically, for example, 53 More than 55% by mass, preferably 55% by mass or more, more preferably 60% by mass or more, still more preferably 65% by mass or more, for example, less than 75% by mass, preferably 73% by mass or less, more Preferably, it is 71 mass% or less, More preferably, it is 69 mass% or less.

  These Al-Cu-Si-Zn-based alloys may be used alone, or two or more types of Al-Cu-Si-Zn-based alloys having different contents of each element may be used in combination.

  An example of a method for producing such Al—Cu—Si—Zn-based alloy powder (that is, brazing filler metal powder) is an atomizing method. Examples of the atomizing method include a centrifugal method and a spraying method.

  In the centrifugal method, for example, a molten metal of the Al—Cu—Si—Zn alloy having the above composition is dropped on a rotating disk, and the obtained fine droplets are cooled and solidified. In this method, a powder having a relatively narrow particle size distribution is usually obtained.

  In the centrifugal method, the particle diameter of the obtained powder can be controlled according to the amount of molten metal used, the number of rotations of the disk, and the like. For example, as the rotational speed level of the disk rotational speed is increased, a brazing filler metal powder having a relatively small particle diameter can be obtained.

  In the spray method, for example, a molten metal of the Al—Cu—Si—Zn alloy having the above composition is sprayed into a protective gas (an inert gas such as argon gas or nitrogen gas), and the resulting fine droplets are cooled. And solidify. In this method, a powder having a relatively wide particle size distribution is usually obtained.

  In the spraying method, the particle diameter of the obtained powder can be controlled according to the amount of molten metal used, the spraying pressure, and the like. For example, as the spray pressure is increased, a brazing filler metal powder having a relatively small particle size can be obtained.

  Furthermore, the particle size of the brazing filler metal powder, for example, a method of sieving the obtained powder with a sieve such as a wire mesh, or a method of mixing two or more kinds of powders can also be adjusted.

In the present invention, the 50% cumulative particle diameter (D ₅₀ ) and the 99% cumulative particle diameter (D ₉₉ ) of the brazing filler metal powder are adjusted to a predetermined range by the above-described method.

More specifically, in the cumulative volume distribution of the brazing filler metal powder, the 50% cumulative particle size (D ₅₀ ) is 80 μm or more, preferably 90 μm or more, more preferably 100 μm or more, even more preferably 110 μm or more, especially Preferably, it is 130 μm or more, 200 μm or less, preferably 190 μm or less, more preferably 180 μm or less, further preferably 170 μm or less, and particularly preferably 160 μm or less,
Further, the 99% cumulative particle size (D ₉₉ ) is 400 μm or less, preferably 350 or less, more preferably 300 μm or less, further preferably 250 μm or less, particularly preferably 200 μm or less, and usually 100 μm or more.

When the 50% cumulative particle diameter (D ₅₀ ) and the 99% cumulative particle diameter (D ₉₉ ) of the brazing filler metal powder are above the lower limit, excessive refinement of the brazing filler metal powder is suppressed, and thus the specific surface area. Does not become excessively large and oxidation of the brazing filler metal powder is suppressed.

  As a result, in brazing, flux is mainly consumed for removing an oxide film on the surface of a member (hereinafter referred to as an Al member) made of aluminum to be joined or an alloy thereof. Excellent brazing properties can be obtained.

On the other hand, when the 50% cumulative particle size (D ₅₀ ) and 99% cumulative particle size (D ₉₉ ) of the brazing filler metal powder are below the lower limit, the specific surface area of the brazing filler metal powder is excessively large. The brazing powder is excessively oxidized. As a result, the flux is consumed for removing the oxide film on the surface of the brazing filler metal powder that has been excessively oxidized in brazing, so that the removal of the oxide film on the surface of the Al member becomes insufficient and excellent brazing properties are obtained. I can't.

In addition, when the 50% cumulative particle size (D ₅₀ ) and the 99% cumulative particle size (D ₉₉ ) of the brazing filler metal powder are below the above upper limit, excessive coarsening of the brazing filler metal powder is suppressed, The specific surface area is not excessively reduced, and the brazing filler metal powder is appropriately oxidized. The moderate oxidation of the brazing material powder slightly increases the melting point of the brazing material powder, so that excessive erosion (erosion) in brazing can be suppressed when the amount of flux is the minimum necessary.

  The cumulative volume distribution of the brazing filler metal powder is measured according to the examples described later.

  In the present invention, the concentration of oxygen in the brazing filler metal powder (such as oxygen contained in the brazing filler metal powder by surface oxidation) is adjusted to a predetermined range.

  Specifically, in the atomizing method (centrifugation method, spraying method) described above, the oxygen concentration of the obtained brazing filler metal powder is adjusted by adjusting the oxygen concentration in the atomizing atmosphere. For example, as the oxygen concentration in the atomizing atmosphere is reduced, a brazing filler metal powder having a lower oxygen concentration is obtained.

  In an atomized atmosphere having the same oxygen concentration, there is a relationship between the particle diameter of the powder and the oxygen concentration of the powder. Specifically, when a powder with a large particle size is produced, the specific surface area of the powder is small, so the oxygen concentration of the powder is low. Conversely, when a powder with a small particle size is produced, the specific surface area is large. Therefore, the oxygen concentration becomes high.

  Therefore, when obtaining a brazing filler metal powder having a desired particle size and oxygen concentration, it is necessary to adjust the manufacturing conditions such as the atomizing method and atomizing atmosphere while paying attention to the above-described relationship between the particle size and the oxygen concentration.

  The oxygen concentration of the brazing filler metal powder is 600 ppm or less, preferably 500 ppm or less, more preferably 400 ppm or less, still more preferably 200 ppm or less, particularly preferably 150 ppm or less, and usually 50 ppm or more.

  When the oxygen concentration of the brazing filler metal powder is below the above upper limit, oxidation of the brazing filler metal powder is suppressed. Therefore, in brazing, it is possible to suppress excessive consumption of flux in order to remove the oxide film of the brazing filler metal powder, and it is mainly consumed to remove the oxide film on the surface of the Al member, resulting in excellent brazing. Sex can be obtained.

  In addition, the oxygen concentration of brazing filler metal powder is measured based on the Example mentioned later.

In the brazing filler metal powder, the Al content ratio, the Cu content ratio, the Si content ratio, and the Zn content ratio are adjusted to predetermined ranges, and the 50% cumulative particle diameter (D ₅₀ ), 99% cumulative particle size (D ₉₉ ) and oxygen concentration are adjusted to the predetermined ranges.

  Therefore, according to the above brazing material powder, it is possible to ensure excellent erosion resistance while securing excellent brazing property in brazing between members made of aluminum or an alloy thereof.

  In brazing with a brazing material powder, a brazing composition is first prepared.

  The brazing composition contains a brazing filler metal powder, a Cs-Al-F flux, and a binder resin.

  Examples of the brazing material powder include the brazing material powder described above.

  The content of the brazing filler metal powder is 40% by mass or more, preferably 45% by mass or more, more preferably 50% by mass with respect to the total amount of the brazing composition from the viewpoint of brazing property and erosion resistance. It is above, and is 80 mass% or less, Preferably, it is 75 mass% or less, More preferably, it is 70 mass% or less.

  If the content rate of the brazing filler metal powder exceeds the lower limit, excellent brazing properties can be obtained. Further, if the content of the brazing filler metal powder is less than the above upper limit, excessive erosion (erosion) can be suppressed and excellent erosion resistance can be obtained.

  The Cs—Al—F based flux is contained in the brazing composition in order to remove the oxide film on the surface while suppressing corrosion of aluminum or an alloy thereof.

  That is, for example, if a chloride-based flux or the like is used, the oxide film can be removed, while corrosion may occur after brazing, but if a Cs-Al-F-based flux is used, corrosion will occur. And the oxide film can be removed.

  Specific examples of the Cs—Al—F flux include cesium fluoroaluminate (non-reactive cesium flux).

  The content ratio of the Cs-Al-F-based flux is 10% by mass or more, preferably 15% by mass or more, more preferably from the viewpoint of brazing property and erosion resistance, with respect to the total amount of the brazing composition. , 20% by mass or more, 40% by mass or less, preferably 35% by mass or less, and more preferably 30% by mass or less.

  If the content ratio of the Cs-Al-F flux exceeds the lower limit, the oxide film can be sufficiently removed and excellent brazing properties can be obtained. Moreover, if the content rate of a Cs-Al-F type | system | group flux is less than the said upper limit, excess erosion (erosion) can be suppressed and the outstanding erosion resistance can be obtained.

  From the viewpoint of brazing and erosion resistance, the Cs-Al-F-based flux is, for example, 20 parts by mass or more, preferably 30 parts by mass or more, with respect to 100 parts by mass of the brazing filler metal powder. 60 parts by mass or less, preferably 50 parts by mass or less.

  Examples of the binder resin include known binder resins, and specific examples include butyl rubber and (meth) acrylic resin.

  Examples of the butyl rubber include known butyl rubber, specifically, a copolymer of isobutylene and isoprene. Such butyl rubber is not particularly limited and can be obtained by a known method.

  These butyl rubbers can be used alone or in combination of two or more.

  In the (meth) acrylic resin, “(meth) acrylic” is defined as “acrylic” and / or “methacrylic”.

  Examples of (meth) acrylic resins include (meth) acrylic acid ester homopolymers, (meth) acrylic acid ester copolymers, copolymers of (meth) acrylic acid esters with hydrophobic monomers and / or hydrophilic monomers, and the like. Is mentioned.

Examples of the (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth ), etc. (meth) acrylic acid _C 1 _{-C 18} alkyl esters such as lauryl acrylate and the like.

  These (meth) acrylic acid esters can be used alone or in combination of two or more.

  Examples of the hydrophobic monomer include styrenes such as styrene, α-methylstyrene, vinyltoluene, and p-chlorostyrene.

  These hydrophobic monomers can be used alone or in combination of two or more.

  Examples of hydrophilic monomers include carboxyl groups such as (meth) acrylic acid, itaconic acid, crotonic acid, (anhydrous) maleic acid, fumaric acid, (anhydrous) citraconic acid, and unsaturated carboxylic acids such as salts thereof. Examples thereof include monomers containing sulfonic acid groups such as styrene sulfonic acid, vinyl sulfonic acid, allyl sulfonic acid, isoprene sulfonic acid, and unsaturated sulfonic acids such as salts thereof.

Further, as the hydrophilic monomer, for example, 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, polypropylene glycol ester (meth) acrylate, polyethylene glycol ester (meth) acrylate, and ester moiety Hydroxyl group-containing (meth) acrylic acid ester (for example, CH ₂ ═C (CH ₃ ) COO (C ₂ H ₄ O) _n H (n is an integer of 2 to 12), etc.) to which alkylene oxide is added ( And hydroxyl group-containing monomers such as (meth) acrylic acid esters.

  These hydrophilic monomers can be used alone or in combination of two or more.

  The (meth) acrylic resin is preferably a (meth) acrylic acid ester homopolymer. Further, from the viewpoint of brazing properties, the monomer constituting the (meth) acrylic resin is preferably a methacrylic monomer (methacrylic acid ester, methacrylic acid, etc.).

  Such a (meth) acrylic resin is not particularly limited, and can be obtained, for example, by radical polymerization of the above monomers by a known polymerization method such as bulk polymerization, solution polymerization, suspension polymerization or the like. Further, the weight average molecular weight of the (meth) acrylic resin can be appropriately set by adjusting the blending amount of the radical polymerization initiator.

  These binder resins can be used alone or in combination of two or more.

  The content ratio of the binder resin is adjusted as a mass ratio (binder resin / (brazing material powder + Cs—Al—F flux)) to the total mass of the brazing filler metal powder and the Cs—Al—F flux.

  The mass ratio of the binder resin (binder resin / (brazing material powder + Cs-Al-F flux)) is, for example, 0.1 / 99.9 or more, preferably 0.2 / 99.8 or more, more preferably 0.5 / 99.5 or more, more preferably 1/99, for example, 25/75 or less, preferably 20/80 or less, more preferably 15/85 or less, still more preferably 10 / 90.

  If the mass ratio of the binder resin (binder resin / (brazing material powder + Cs—Al—F flux)) exceeds the lower limit, excessive erosion (erosion by the brazing filler metal powder and the Cs—Al—F flux) (Jon) can be suppressed and erosion resistance can be improved. Furthermore, when the brazing composition is in the form of a paste (described later), separation of the solvent can be suppressed and excellent coating properties can be obtained.

  Moreover, if the mass ratio of the binder resin (binder resin / (brazing material powder + Cs-Al-F-based flux)) is below the above upper limit, the residual volatilization of the binder resin is reduced and excellent brazing properties are obtained. be able to. Moreover, generation | occurrence | production of byproduct gas at the time of brazing can be suppressed, and it is excellent also in workability | operativity. Furthermore, when the brazing composition is in the form of a paste (described later), it is possible to suppress an excessive increase in the viscosity of the brazing composition and obtain excellent coating properties.

  The content ratio of the binder resin is, for example, 0.1% by mass or more, preferably 0.2% by mass or more, more preferably, relative to the total amount of the brazing composition from the viewpoints of brazing and workability. 0.5% by mass or more, for example, 2.0% by mass or less, preferably 1.5% by mass or less, and more preferably 1.0% by mass or less.

  Further, the brazing composition can further contain a solvent.

  Examples of the solvent include aliphatic hydrocarbon-based / alicyclic hydrocarbon-based (naphthene-based) organic solvents such as n-hexane, cyclohexane, methylcyclohexane, and octane, for example, aromatic hydrocarbon-based organic solvents such as toluene and xylene. Examples include hydrocarbon organic solvents such as solvents (hydrocarbon organic solvents having an aromatic ring). Further, examples of the solvent include hydrocarbon organic solvents having a hydroxyl group such as methyl alcohol, ethyl alcohol, and isopropyl alcohol.

  These solvents can be used alone or in combination of two or more.

  On the other hand, hydrocarbon organic solvents having an aromatic ring may be inferior in occupational health, safety, environmental conservation, and odor.

  In addition, the hydrocarbon organic solvent having a hydroxyl group may be inferior in storage stability. For example, when water coexists, it reacts with the brazing filler metal powder over time to improve storage stability and safety. May decrease.

  Therefore, the solvent is preferably a hydrocarbon-based organic solvent having no aromatic ring and a hydroxyl group, specifically, an aliphatic hydrocarbon-based / alicyclic hydrocarbon-based (naphthene-based) organic solvent.

  If an aliphatic hydrocarbon / alicyclic hydrocarbon (naphthene) organic solvent is used, occupational health, safety, environmental conservation, odor and storage stability can be ensured.

  Further, the boiling point of the solvent is, for example, 150 ° C. or higher, preferably 180 ° C. or higher, from the viewpoint of the smoothness of work by suppressing odor.

  Such a solvent is also available as a commercial product. Specifically, for example, trade name “Exsol D80” (manufactured by Exxon Mobil, naphthenic hydrocarbon organic solvent, boiling point (initial boiling point) 205 ° C).

  The blending ratio of the solvent is not particularly limited, and is appropriately set according to the purpose and application. Specifically, in the brazing composition, the blending ratio of the solvent is the balance of the brazing filler metal powder, the Cs—Al—F based flux, and the binder resin.

  Further, the brazing composition may be prepared, for example, with an antioxidant (for example, dibutylhydroxytoluene), a corrosion inhibitor (for example, benzotriazole), an antifoaming agent (for example, silicon oil, glycerin, etc.) ), Thickeners (for example, waxes, hydrogenated oils, fatty acid amides, polyamides, etc.), colorants and other various additives can be contained as long as the effects of the present invention are not impaired.

  And the composition for brazing can be obtained by mixing and stirring each component by a well-known method in said ratio.

  For example, when the brazing composition contains the above-described solvent, the brazing composition is obtained, for example, as a paste-like composition (brazing paste).

  Moreover, the shape of the brazing composition is not limited to a paste form, and may be a solid form.

  The solid brazing composition is prepared by, for example, preparing a brazing composition without using the above-mentioned solvent, and molding the obtained brazing composition by a known method such as press molding. Obtainable.

  Further, for example, the paste-like brazing composition described above is molded into an arbitrary shape and then dried, or, for example, a paste-like brazing composition is added with a thickener (such as wax) as an additive. ) Can also be obtained.

  Examples of the shape of the solid brazing composition include a rod shape, a plate shape, a pipe shape, a wire shape, and a ring shape, preferably a pipe shape and a ring shape, and more preferably a ring shape. Shape. In addition, after forming the brazing composition into a plate shape or a rod shape, it can be bent into a pipe shape or a ring shape.

  And since such a brazing composition contains the above-mentioned brazing filler metal powder, it has excellent corrosion resistance while securing excellent brazing properties in brazing between members made of aluminum or its alloys. Can also be secured.

  Therefore, the above brazing composition is suitably used for brazing members (Al members) made of aluminum or an alloy thereof.

  The aluminum alloy is an alloy containing aluminum as a main component, and a known aluminum alloy is used. In the aluminum alloy, the components contained in addition to aluminum are not particularly limited, and are appropriately set according to the purpose and application.

  The shape of the Al member is not particularly limited, and examples thereof include a plate shape, a tube shape, a pipe shape, a cylindrical shape, and a prismatic shape. Preferably, a pipe shape and a pipe shape are mentioned.

  Particularly preferably, the Al member has a tube shape or a pipe shape.

  Hereinafter, a method for joining tube-shaped or pipe-shaped Al members will be described in detail with reference to FIGS. 1 and 2.

  In FIG. 1, a heat exchanger 10 is a known cross fin tube type heat exchanger, and includes a fin laminate 5 and a heat exchanger joining pipe 1.

  The fin laminated body 5 is a heat radiating member in the heat exchanger 10 and is formed by laminating a plurality of fin plates 6 with a predetermined interval therebetween.

  The heat exchanger joining pipe 1 is a pipe member for circulating the refrigerant in the heat exchanger 10, and is provided with one or a plurality according to the size of the heat exchanger 10, and penetrates the fin laminate 5 in the laminating direction. Are arranged to be.

  More specifically, as shown in FIG. 2, the heat exchanger joining pipe 1 includes a refrigerant pipe 2 as a first Al member and a connection pipe 3 as a second Al member.

  The refrigerant pipe 2 is a straight pipe-shaped Al member, and a plurality of refrigerant pipes 2 are provided for circulating a known refrigerant in the heat exchanger 10.

  The refrigerant pipe 2 includes a straight pipe portion 21 and an auxiliary portion 22.

  The straight pipe portion 21 is a pipe member having a constant inner diameter and outer diameter, and is provided in a plurality (see FIG. 1) according to the size of the heat exchanger 10 so as to penetrate the fin laminate 5 in the laminating direction. The fin plates 6 are spaced apart from each other in the longitudinal direction. Such a straight pipe portion 21 allows the refrigerant to pass inside and is in contact with the fin laminate 5 on the outside, thereby ensuring heat exchange.

  The auxiliary portion 22 is an opening end portion of a substantially tapered shape that widens in steps, and is formed at both ends of the straight pipe portion 21 so as to be exposed from the fin plate 6. Such an auxiliary part 22 may be formed integrally with the straight pipe part 21, or may be formed as a separate member from the straight pipe part 21 and connected to the straight pipe part 21.

Thickness _{L 1} of the refrigerant pipe 2 is less 0.45 mm.

If the thickness L ₁ of the refrigerant pipe 2 is less than the above upper limit, it is possible to reduce the weight of the heat exchanger 10 can be further exhibits excellent brazing properties and corrosion resistance.

  The connecting pipe 3 is an inverted U-shaped Al member and is provided to connect adjacent refrigerant pipes 2 to each other.

  More specifically, a plurality of connection pipes 3 (see FIG. 1) are provided according to the number of refrigerant pipes 2, and one end of the connection pipe 3 is an end of one refrigerant pipe 2 (auxiliary). Part 22), and the other end of the connecting pipe 3 is fitted to the end (auxiliary part 22) of the other adjacent refrigerant pipe 2.

Thickness _{L 2} of the connection pipe 3 is, for example, 1.5mm or less.

If the thickness L ₂ of the connection pipe 3 is less than the above upper limit, it is possible to reduce the weight of the heat exchanger 10 can be further exhibits excellent brazing properties and corrosion resistance.

Further, the wall thickness L ₂ of the connecting pipe 3 is preferably thicker than the wall thickness L ₁ of the refrigerant pipe 2, specifically, with respect to the wall thickness L ₁ of the refrigerant pipe 2 (relatively thin member). connecting tube 3 (relatively thick member) thickness ratio of the thickness _{L 2} of the (connection pipe 3 of the thickness _{L 2} / thickness _{L 1} of the refrigerant pipe 2) is, for example, 1.5 or more, preferably, 2 For example, it is 10 or less, preferably 5 or less.

  If the thickness ratio is in the above range, the heat exchanger 10 can be reduced in weight, and further, excellent brazing properties and erosion resistance can be exhibited.

  Then, the refrigerant pipe 2 and the connecting pipe 3 are brazed (joined) with the brazing composition 4 to form the heat exchanger assembly 1.

  Hereinafter, a method of brazing the refrigerant pipe 2 and the joining pipe 3 will be described with reference to FIG.

  In this method, first, as shown by an arrow in FIG. 3A, the end portion (auxiliary portion 22) of the refrigerant pipe 2 and the end portion of the connection pipe 3 are fitted.

  As a result, as shown in FIG. 3B, the connecting pipe 3 and the refrigerant pipe 2 partially overlap, and the lower end edge of the connecting pipe 3 contacts the upper end edge of the main pipe portion 21 (the lower end edge of the auxiliary portion 22). Alternatively, the lower end edge of the connection pipe 3 is disposed in the vicinity of the upper end edge of the main pipe portion 21.

  Next, in this method, as shown in FIG. 3C, the brazing composition 4 described above is disposed on the upper end portion of the auxiliary portion 22 (the upper end portion of the paper surface of FIG. 3).

  For example, when the brazing composition 4 is in a paste form, the brazing composition 4 is applied so as to cover the upper end edge of the auxiliary portion 22. Thereafter, the brazing composition 4 is dried as necessary. The drying conditions are appropriately set according to the formulation of the brazing composition 4 and the like.

  In addition, for example, when the brazing composition 4 is formed in a predetermined shape (preferably a ring shape or a pipe shape), the brazing composition 4 is formed so as to cover the upper end edge of the auxiliary portion 22. Deploy.

  Thereafter, in this method, the brazing composition 4 is heated.

  The heating method is not particularly limited, and a known brazing method can be employed. Specifically, a brazing method in a furnace or the like can be employed.

  The heating conditions are appropriately set according to the melting point and thickness of the Al member, the melting point of the brazing filler metal powder, the melting point of the Cs—Al—F flux, and the like. For example, the temperature is equal to or higher than the melting point of the brazing filler metal powder and higher than the melting point of the Cs—Al—F flux and lower than the melting point of the Al member, and is equal to or longer than the time for the brazing filler metal powder to sufficiently melt.

  Specifically, for example, when the thickness of the Al member is 0.5 mm to 5 mm, the heating temperature is, for example, 420 ° C. or higher, preferably 450 ° C. or higher, for example, 620 ° C. or lower, preferably It is 600 degrees C or less. The heating time is, for example, 10 seconds or longer, preferably 15 seconds or longer, for example, 50 seconds or shorter, preferably 40 seconds or shorter.

  The atmospheric conditions include, for example, a vacuum atmosphere, for example, an inert gas atmosphere such as argon gas and nitrogen gas, and the atmospheric conditions preferably include an oxygen concentration of 50 ppm or less.

  As a result, the brazing composition 4 dissolves and flows, and the brazing composition 4 fills the gap between the refrigerant pipe 2 (auxiliary portion 22) and the connecting pipe 3 as shown in FIG. Is done. Thereafter, by cooling, the refrigerant pipe 2 and the joining pipe 3 are brazed (joined), and the joining pipe 1 for a heat exchanger as a joined body thereof is obtained.

  Since such a heat exchanger joining pipe 1 is obtained by using the above brazing material powder and the brazing composition, it is excellent in brazing and erosion resistance.

  Specifically, for example, in the field of the heat exchanger 10, in order to reduce the weight and increase the efficiency, the heat exchanger joint pipe 1 (the refrigerant pipe 2 and / or the connection pipe 3) is required to be thin. Yes.

  However, when a brazing paste having excellent brazing properties is used for the thin-walled refrigerant pipe 2 and / or connection pipe 3, excessive erosion (erosion) occurs in the refrigerant pipe 2 and the connection pipe 3 as shown in FIG. There is a problem inducing the durability of the heat exchanger. That is, when trying to obtain excellent brazing properties, excessive erosion (erosion) is likely to occur, and there is a contradiction that brazing properties are reduced when erosion (erosion) is to be suppressed.

  On the other hand, the brazing material powder and the brazing composition described above can have both brazing properties and erosion resistance.

  Therefore, the joining tube 1 for heat exchangers obtained by using the brazing filler metal powder and the brazing composition described above can suppress erosion of the piping while being excellent in brazing property, and as a result, is excellent in durability. .

  In the above description, brazing of the refrigerant pipe 2 as the first Al member and the connection pipe 3 as the second Al member has been described. However, the first Al member and the second Al A member is not limited to these, It can select from a well-known Al member suitably.

  In such a case, the thickness of any one of the members (relatively thin members) is preferably equal to the thickness of the above-described refrigerant pipe 2 (preferably 0.45 mm or less).

  Further, preferably, the thickness of the other member (a relatively thick member) is equal to the thickness of the above-described joining tube 3.

  If the thickness of the Al member is less than the above upper limit, it is possible to reduce the weight while ensuring brazing and erosion resistance.

Preferably, the ratio of the thickness of the second Al member (relatively thick member) to the thickness of the first Al member (relatively thin member) is relative to the thickness L ₁ of the refrigerant pipe 2 described above. thickness ratio of the thickness L ₂ of the connection pipe 3 equivalent (preferably, 2 or more).

  Further, if the thickness ratio exceeds the lower limit, dissolution of the Al member can be suppressed, and erosion resistance can be improved. Moreover, if the wall thickness ratio is below the above upper limit, the temperature difference between the Al members can be reduced, and brazing performance can be improved.

  Next, although this invention is demonstrated based on an Example and a comparative example, this invention is not limited by the following Example. “Part” and “%” are based on mass unless otherwise specified. In addition, specific numerical values such as a blending ratio (content ratio), physical property values, and parameters used in the following description are described in the above-mentioned “Mode for Carrying Out the Invention”, and a blending ratio corresponding to them ( Substituting the upper limit value (numerical value defined as “less than” or “less than”) or the lower limit value (number defined as “greater than” or “exceeded”) such as content ratio), physical property values, parameters, etc. be able to.

Examples 1 to 12, Reference Examples 1 to 4 and Comparative Examples 1 to 4
(1) as a brazing filler metal powder brazing material powder, the composition shown in Table 1 to Table 3, a powder of Al-Cu-Si-Zn alloy having a particle diameter _{(D 50} and _{D 99)} and oxygen concentration were obtained respectively . In the composition in the table, Al contains inevitable impurities.

  The brazing filler metal powder was produced by a centrifugal method or a spray method.

  In the case of the centrifugal method, the particle diameter of the brazing filler metal powder was adjusted to the value described in the table by adjusting the disk rotation speed level. In addition, the disk rotation speed level (1-6) described in the table indicates that the higher the number, the higher the rotation speed.

  In the case of the spray method, the particle diameter of the brazing filler metal powder was adjusted to the value described in the table by adjusting the spray pressure level. In addition, the spray pressure level (1-5) as described in a table | surface shows that it is so high pressure that a number is high.

  Further, the brazing filler metal powder after the production was adjusted so that the particle diameter of the brazing filler metal powder was within a predetermined range or outside the predetermined range by sieving with a wire mesh or mixing two kinds of powders.

  Furthermore, the oxygen concentration of the brazing filler metal powder was adjusted to the value described in the table by adjusting the atmospheric conditions (particularly the oxygen concentration in the atmosphere) at the time of production. In addition, nitrogen described in the table indicates a nitrogen atmosphere. Quasi-nitrogen refers to a mixed atmosphere of nitrogen and air. Moreover, air | atmosphere shows an air atmosphere.

  For the measurement of the particle diameter of the brazing filler metal powder, a laser light diffraction / scattering particle size distribution analyzer MT3000II (manufactured by MICROTRAC) was used. Using isopropyl alcohol (IPA; refractive index 1.38) as a solvent, the DV value of the sample (a value related to the integrated scattered light amount of particles captured by a detector placed in front of the laser, measured concentration The sample was adjusted so that the standard of the microtrack to determine the range was 0.01 to 1.0, and after applying ultrasonic waves for 3 minutes using an ultrasonic device (output 40 W), the flow rate was 80%. Measurement was performed while circulating at 40 cc / minute (measurement conditions: particle permeability... Reflection).

  The oxygen concentration of the brazing filler metal powder is measured by an inert gas melting-infrared absorption method using an oxygen / nitrogen analyzer EMGA-620W (Horiba, Ltd.) to measure the oxygen concentration of the brazing filler metal powder. did.

(2) Brazing composition 51 parts by weight of the above brazing filler metal powder, 22 parts by weight of Cs-Al-F-based flux (cesium fluoroaluminate), 0.5 part by weight of binder resin (butyl rubber), and hydrocarbon 26.5 parts by mass of the organic solvent was mixed and stirred to obtain a paste-like brazing composition.

  In Example 8, a solid brazing composition was obtained without using a hydrocarbon-based organic solvent. Specifically, 69 parts by mass of brazing filler metal powder, 30 parts by mass of Cs—Al—F flux and 1 part by mass of binder resin were kneaded, poured into a ring-shaped mold, and press molded.

(3) Bonded body As shown in Tables 1 to 3, an aluminum tube having a thickness A (JIS A1050, diameter φ6 mm) and an aluminum tube having a thickness B (JIS A1050, diameter φ6 mm) were prepared. In addition, the edge part of the aluminum tube was a shape which can be mutually fitted as FIG. 1 shows.

  Next, the end portions of the aluminum tubes were fitted, and the brazing composition was disposed in the fitting portion (see FIG. 3).

  Then, the aluminum tubes fitted to each other were heated and brazed. At this time, the brazing temperature is adjusted to be not less than the melting point of the brazing filler metal powder, not less than the melting point of the Cs-F-Al flux and less than the melting point of the Al member, and the brazing powder is melted. Adjust to penetrate the joint.

  Specifically, when the thickness A of the Al member was 0.2 mm, heating was performed at about 420 ° C. to 620 ° C. for 15 seconds to 50 seconds.

  Thus, a joined body in which two aluminum tubes were joined was obtained.

  In each example and each comparative example, a relatively thin (less than 1 mm) thick Al member was used. On the other hand, in each reference example, a relatively thick (1 mm or more) thick Al member was used.

<Evaluation>
The obtained joined body was cut along the longitudinal direction, and the cross section was observed with a light microscope to evaluate brazing property and erosion resistance (see FIG. 4).

(1) Brazing property The brazing property was evaluated by calculating the ratio of the length of the brazing piece generating portion to the total length of the joining portion (brazing piece length / joining portion length). The results are shown in Tables 1 to 3. The evaluation criteria are as follows.
A: The brazing piece length is less than 10% of the total length of the joint.
Δ: The brazing piece length is 10% or more and less than 60% of the total length of the joint.
X: The brazing piece length is 60% or more of the total length of the joined portion, or joining is impossible.

(2) Erosion resistance The ratio of the maximum value of the erosion depth of the brazing material to the thickness of the Al member (maximum erosion depth / Al member thickness) was calculated to evaluate the erosion resistance. The results are shown in Tables 1 to 3. The evaluation criteria are as follows.

The erosion depth was measured for an aluminum tube (Al member) having a wall thickness B. Further, it was considered that the same degree of erosion occurred in the aluminum pipe having the wall thickness A.
A: The maximum erosion depth is less than 5% of the thickness of the Al member.
Δ: The maximum erosion depth is 5% or more and less than 20% of the thickness of the Al member.
X: The maximum erosion depth is 20% or more of the thickness of the Al member, or erosion can be visually confirmed.

Claims (6)

A brazing material powder for brazing members made of aluminum or an alloy thereof,
Containing Al, Cu, Si and Zn,
For the total amount of the brazing powder,
Cu content ratio is more than 20.0 mass%, less than 27.0 mass%,
The content ratio of Si is 2.0 mass% or more and 10.0 mass% or less,
Zn content is 3.0% by mass or more and 10.0% by mass or less,
The balance consists of Al and inevitable impurities,
In the cumulative volume distribution of the brazing powder,
50% cumulative particle size (D ₅₀ ) is 80 μm or more and 200 μm or less,
99% cumulative particle size (D ₉₉ ) is 400 μm or less,
The brazing filler metal powder, wherein the brazing filler metal powder has an oxygen concentration of 600 ppm or less. A brazing composition comprising a brazing powder, a Cs-Al-F-based flux, and a binder resin,
The brazing material powder is the brazing material powder according to claim 1,
With respect to the total amount of the brazing composition,
The brazing powder content is 40% by weight or more and 80% by weight or less,
The content ratio of the Cs-Al-F-based flux is 10% by mass or more and 40% by mass or less,
The mass ratio of the binder resin to the total mass of the brazing filler metal powder and the Cs—Al—F flux (binder resin / (brazing filler powder + Cs—Al—F flux)) is 0.1 / 99.9. The composition for brazing characterized by being 25/75 or less. The brazing composition is
The brazing composition according to claim 2, which has any one shape selected from the group consisting of a paste shape, a rod shape, a plate shape, a pipe shape, a line shape, and a ring shape. By the brazing composition according to claim 2 or claim 3, a joined body in which members made of aluminum or an alloy thereof are joined together,
The member is a tube-shaped or pipe-shaped member,
The ends of the members are fitted together,
In the fitting portion by the fitting, an outer diameter of one member is less than an inner diameter of the other member. The joined body according to claim 4, wherein the thickness of any one of the members is 0.45 mm or less. The thickness of one of the members is thicker than the thickness of the other member,
The joined body according to claim 4 or 5, wherein a thickness ratio of the thickness of the thick member to the thickness of the thin member is 2 or more.

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