JP2000225491A - Flux mixture for brazing aluminum member, brazing method and heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a sufficient fillet in which no expensive brazing sheet is used, the changes in dimension are not reduced, the cleaning is unnecessary, and the influence of the brazeability and the residue is taken into consideration by adding a two-element eutectic compound consisting of aluminum fluoride and potassium fluoride of specified quantity to a flux mixture. SOLUTION: A flux mixture is formed preferably by adding >=10 wt.% to <=30 wt.% two-element compound consisting of aluminum fluoride and potassium fluoride to a flux mixture having the composition consisting of non-corrosive silica fluoride compound and fluoride. Then, <=60 wt.% mixture consisting of a metal and/or alloy is added to the flux mixture. The metal includes at least one of aluminum, zinc, tin, indium, nickel, titanium or phosphor, and the alloy is a powder AS-Si alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brazing flux for connecting aluminum members, a brazing method and a heat exchanger, and relates to a method for converting silicon (Si) from a silicon fluoride compound contained in a flux without supplying a brazing material. S
i) is precipitated, and a flux mixture for brazing an aluminum member using an Al-Si eutectic liquid phase of the precipitated Si and aluminum (Al) melted from the aluminum member, a brazing method, and a method using the same. It relates to a heat exchanger.

[0002]

2. Description of the Related Art For example, brazing for assembling a metal member with an aluminum brazing sheet is performed for cooling an automobile part or assembling a heat exchanger such as an air conditioning system.

Generally, in brazing a metal member, a corrosive flux such as zinc chloride is applied to the metal member before brazing to remove an oxide film formed on the metal surface to prevent reoxidation. The brazing material is fused to the brazing portion by improving the wettability of the surface of the aluminum member. Others
Using an aluminum base material as a core material, forming each member using a brazing sheet coated on one or both sides with a wax,
After assembling each member, by heating around 600 ° C,
A method for melting a brazing material layer to form a heat exchanger is known.

[0004] The brazing of a metal member and the flux were in a close relationship. That is, unless the oxide film formed on the surface of the aluminum member or the like is removed by the flux, the brazing material cannot be fused to the brazed portion and brazing cannot be performed. Therefore, the quality of the flux determines the brazing property.

On the other hand, flux residues such as zinc chloride after brazing have strong corrosiveness, and require a complicated washing process for removing the flux.

[0006]

However, the brazing sheet coated with the brazing material is expensive, and there is a problem that the manufacturing cost is increased.

Further, in a heat exchanger laminated by using a brazing sheet in which both sides or one side of a core material is coated with a brazing material, after assembling the parts to each other, brazing a joint portion of the parts is performed. The dimensional change corresponding to the melting of the coated brazing material occurs, and there is a problem that the change in size from about 2 mm to about 3 mm deteriorates the assemblability and the brazing yield (due to leakage or the like).

Further, as described above, in the case of a flux containing a chloride as a main component, a water-soluble, hygroscopic and corrosive residue may be generated, and thus cleaning is required.

Therefore, as a flux, potassium silicon fluoride (K ₂ SiF ₆ ) is used as a main component, and K ₂ SiF
_A method has been proposed in which Si in No. ₆ is precipitated and reacted with an aluminum base material to form an Al-Si brazing material layer and brazing.

That is, a silicon-containing compound (K ₂ SiF
₆ ) As shown in the following chemical formula, Si is deposited,
Reacts with Al in the member.

3K₂SiF₆+ 4Al = 3Si + 2KA
IF₄+ 2K₂AlF₅  In this case, a silicon-containing compound containing Si serving as a brazing filler metal is used.
In order to lower the brazing temperature,₃Etc.
Aluminum fluoride is used as a mixture.

For example, as described in Japanese Patent No. 2607585, brazing is performed using a basic composition in which K ₂ SiF ₆ and AlF ₃ are mixed in a predetermined amount. In addition, these basic compositions use a predetermined dispersant to reduce residues.

However, as described above, K ₂ SiF ₆ and Al
When the basic composition composed of F ₃ is used, if the content of K ₂ SiF ₆ is less than 30% by weight, the amount of Si deposited is insufficient, sufficient brazing properties cannot be obtained, and K ₂ SiF ₆ cannot be obtained. 95
When the content is more than 10% by weight, there is a phenomenon that the melting point of the mixture increases and it becomes difficult to melt.

Further, even when fluoride (aluminum fluoride) is added to lower the melting point, black or brownish residues due to unreacted Si may remain.

[0015] Therefore, the adhesive portion (fillet) generated at the connecting portion of the two members may be small, which may cause a problem in brazing properties.

Accordingly, the present invention is to form a sufficient fillet without using an expensive brazing sheet, reducing dimensional change, not requiring cleaning, and considering the effects of brazing properties and residues. It is an object of the present invention to provide a flux mixture for brazing, a brazing method, and a heat exchanger, in which brazing strength is ensured.

[0017]

According to the first aspect of the present invention, there is provided a flux mixture comprising a non-corrosive silicon fluoride compound and a fluoride, wherein the flux mixture is formed on the surface of a connecting portion of an aluminum member. Apply the flux mixture,
In a flux mixture for brazing an aluminum member connecting the connecting portions by heating in a non-oxidizing atmosphere, the flux mixture is composed of 10% by weight or more and 30% by weight or less of aluminum fluoride and potassium fluoride. It is a flux mixture for brazing aluminum members to which a binary eutectic compound has been added.

As described above, a binary eutectic compound consisting of aluminum fluoride and potassium fluoride is added to a flux mixture as a composition of a non-corrosive silicon fluoride compound and a fluoride in an amount of from 10% by weight to 30% by weight. When the added flux mixture is used, it is possible to connect the connecting portions of the aluminum members using only the flux mixture without using a brazing sheet in which a brazing material layer is coated on a core material.

That is, Si precipitated from the silicon fluoride compound reacts with Al in the aluminum member to form Al-
The Si eutectic brazing material phase is formed, and the connection portions of the aluminum members are joined by brazing.

Therefore, the connection portion of the aluminum member can be connected to each other without using the brazing sheet coated with the brazing material layer by the flux mixture generally used for cleaning the oxide film on the surface of the aluminum member. And the cost can be reduced. Further, according to the flux mixture of the present invention, since the dimensional change of the assemblability of the members due to the melting of the brazing material does not occur, the degree of freedom of design, the yield, and the assemblability can be improved. In other words, when a brazing sheet is used, the brazing material layer coated on the core material is melted during heating, the range between the connecting parts of the members becomes large, and the dimensional design is strictly determined in consideration of the brazing material melting portion. Had to do. However, when the flux mixture of this example is used, the difference in dimensional change caused by melting is reduced, so that each member can be designed without considering strict dimensional control.

Further, when a binary eutectic compound consisting of aluminum fluoride and potassium fluoride is added to a flux mixture consisting of a silicon fluoride compound and a fluoride, the melting point of the flux mixture drops, and this eutectic compound is added. It is possible to reduce the black or brownish residue that has been observed when a flux mixture composed of a silicon fluoride compound and a fluoride that is not used is melted.

The flux mixture comprising the silicon fluoride compound and the fluoride reacts with Si precipitated from the mixture and Al of the aluminum member to form a eutectic brazing material phase, thereby connecting the connection portions of the aluminum member. Is the precipitation S
If i does not sufficiently react with the base material Al and unreacted Si is present, this black or brown residue is left, and the aesthetic appearance is impaired, and the brazing property may be reduced.

According to the present invention, by adding a binary eutectic compound consisting of aluminum fluoride and potassium fluoride to a flux mixture consisting of a silicon fluoride compound and a fluoride, the melting point of the flux mixture is lowered and the precipitated Si
In addition, it is possible to improve the eutectic reaction of the base material Al to reduce unreacted Si, and to reduce the problematic black or brown residue. Here, if the amount of the mixture of aluminum fluoride and potassium fluoride is less than 10%, the melting point does not drop to the target temperature, and if it is more than 30% by weight, the amount of Si deposited decreases. Good brazing properties cannot be obtained.

Further, by improving the reactivity of the precipitated Si, it is possible to generate a brazing filler metal phase having a good fillet forming ability, and to obtain the same brazing strength as when a brazing sheet is used. Become.

The invention described in the second claim of the present application is a flux mixture comprising a non-corrosive silicon fluoride compound and a fluoride, wherein the flux mixture is applied to the surface of a connecting portion of an aluminum member, A brazing flux mixture for an aluminum member that connects the connecting portions by heating in a non-oxidizing atmosphere, wherein the mixture of metals and / or alloys is added to the flux mixture. It is a flux mixture.

As described above, when a mixture of a metal and / or an alloy is added to a flux mixture of a silicon fluoride compound and a fluoride, Si precipitated from the flux mixture is only aluminum of the aluminum member. Not to react with metal and / or metal in alloy,
The reactivity of the precipitated Si is improved, and unreacted Si, which has been conventionally considered to be the cause of the residue such as black, is reduced, and the generation of the residue such as black is prevented, so that the appearance can be improved. In addition, by improving the reactivity with Si precipitated from the flux mixture, not only the Al-Si eutectic liquid phase but also the metal-Si eutectic liquid phase increases the brazing filler metal phase, thereby achieving a sufficient fillet forming ability. Can be obtained.

According to a third aspect of the present invention, in the second aspect of the present invention, the flux mixture containing the silicon fluoride compound and the fluoride as a composition comprises 60% by weight or less of a metal and / or an alloy. It is a flux mixture for brazing aluminum members to which the mixture has been added.

As described above, by adding a mixture of a metal and / or an alloy of 60% by weight or less to a flux mixture composed of a silicon fluoride compound and a fluoride, not only Al of the aluminum member but also the added metal and And / or alloy metal, Si precipitated from the flux mixture
Reacts, reduces unreacted Si, increases the amount of brazing filler metal phase, prevents black and other residues caused by unreacted Si, improves the appearance, and improves brazing properties Becomes

The addition amount of the metal and / or alloy mixture is 60
When the content is more than 10% by weight, the amount of the mixture of the silicon fluoride compound and the fluoride is reduced, and the amount of Si precipitated from the flux mixture is reduced. It is difficult to obtain the attachment property.

According to a fourth aspect of the present invention, there is provided a flux mixture comprising a non-corrosive silicon fluoride compound and a fluoride, wherein the flux mixture is applied to the surface of a connecting portion of an aluminum member, In a flux mixture for brazing an aluminum member connecting the connecting portions by heating in a non-oxidizing atmosphere, the flux mixture contains a mixture of 40% by weight or less of a metal and / or alloy and 10% by weight or more. This is a flux mixture for brazing aluminum members to which a binary eutectic compound comprising aluminum fluoride and potassium fluoride of 30% by weight or less is added.

As described above, the mixture of the metal and / or the alloy of 40% by weight or less and the mixture of 10% by weight or more
When a binary eutectic compound consisting of 0% by weight or less of aluminum fluoride and potassium fluoride is added, the metal precipitated from the mixture and the melting point drop of the flux mixture due to the addition of the eutectic compound cause a decrease in the flux mixture. Improve the reactivity of precipitated Si, reduce unreacted Si, prevent the generation of black and other residues due to unreacted Si,
By increasing the amount of the brazing material phase composed of the Al-Si eutectic and the metal-Si eutectic, it becomes possible to obtain good brazing properties.

The mixture of metals and / or alloys is
If more than 10% by weight is added to the flux mixture, the amount of the mixture containing the silicon fluoride compound and the fluoride as a composition decreases, and the amount of Si precipitated from the flux mixture decreases. Eutectic and metal
Si eutectic brazing material phase is reduced, and it is difficult to obtain good brazing properties.

If the addition amount of the eutectic compound consisting of aluminum fluoride and potassium fluoride is less than 10%, the melting point does not drop to the target temperature. The amount is reduced and good brazing properties cannot be obtained.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the metal is at least one of aluminum, zinc, tin, indium, nickel, titanium, and phosphorus. Is a flux mixture for brazing aluminum members.

As described above, the metals to be added to the flux mixture containing the silicon fluoride compound and the fluoride as the composition are Al, zinc (Zn), tin (Sn) and indium (I
n), nickel (Ni), titanium (Ti), or phosphorus (P) powder, Si precipitated from the flux mixture and the metal form a eutectic, and the metal-Si Unreacted Si to form a brazing filler metal phase
Is reduced, the generation of black residue is prevented, and the brazing material phase having good fillet-forming ability can obtain the same brazing strength as when a brazing sheet is used, thereby improving the brazing property. It becomes possible.

The invention described in claim 6 of the present application is the invention according to any one of claims 2 to 4, wherein the alloy is a flux mixture for brazing an aluminum member, which is an Al-Si alloy powder.

As described above, when the alloy to be added to the flux mixture containing the silicon fluoride compound and the fluoride as a composition is Al-Si alloy powder, Si precipitated from the flux mixture reacts with the base material Al. Not only the generated brazing material phase but also the added Al-Si alloy increases the amount of the brazing material phase, thereby making it possible to improve brazing properties. Further, when an Al-Si alloy is added, the melting point is lowered to 577 ° C. (melting point of aluminum is 660 ° C.), so that the reactivity of precipitated Si is improved, and the generation of black and other residues caused by unreacted Si is prevented. In addition, a good appearance can be obtained.

According to a seventh aspect of the present invention, there is provided a flux mixture for brazing an aluminum member according to any one of the second to sixth aspects, wherein the metal or alloy has an average particle size of 45 μm or less. is there.

As described above, when the average particle size of the metal or alloy added to the flux mixture containing the silicon fluoride compound and the fluoride is 45 μm or less, the surface area which reacts with Si precipitated from the flux mixture is considered. And the diffusion of Si is accelerated, so that the reactivity of the precipitated Si is improved, and a metal-Si eutectic brazing material phase is formed at a low melting point, so that the brazing property can be improved. In addition, it is possible to prevent the generation of residues such as black due to unreacted Si, and to obtain good brazing properties.

According to an eighth aspect of the present invention, in the invention according to any one of the second to seventh aspects, the metal or alloy has an average particle size of 45 μm or less, and is made of the metal and / or alloy. This is a flux mixture for brazing an aluminum member having an oxygen content of 1% or less in the mixture.

As described above, the finer the particle size of the metal or alloy added to the flux mixture containing the silicon fluoride compound and the fluoride, the larger the surface area becomes.
The diffusion rate is increased, and a metal-Si eutectic brazing material phase is generated at a low melting point, so that the brazing property is improved.

On the other hand, if the particle size is too small, the oxygen content contained in the mixture of the metal and the alloy increases, and the reaction between the precipitated Si and the metal and / or the alloy is hindered, and the unreacted Si increases. However, a black or brown residue is observed.

Therefore, it is desirable that the average particle size of the mixture of the metal and the alloy added to the flux mixture is 45 μm or less, and the oxygen content in the mixture is 1% or less. If the oxygen content in the mixture of metal and alloy is 1% or more, the deposited
Of unreacted Si increases, and unreacted Si increases.
, Black or brown residues are often observed.

According to a ninth aspect of the present invention, in the invention according to any one of the first to seventh aspects, the silicon fluoride compound as the composition of the flux mixture is K ₂
SiF ₆ , and the fluoride is AlF ₃ is a flux mixture for brazing aluminum components.

As described above, when the flux mixture having the composition of K ₂ SiF ₆ and AlF ₃ is applied to the connection surface of the aluminum member and heated in a non-oxidizing atmosphere, Si precipitates from the flux mixture, Forming Al and Al-Si eutectic brazing filler metal phase of aluminum member, not only cleaning of oxide film, which is the purpose of conventional flux coating, but also connecting parts of aluminum member by the Al-Si eutectic brazing filler metal phase It is possible to do.

The melting temperature of K ₂ SiF ₆ is 750.
Because of the high temperature of 600 ° C., AlF ₃ is added to lower the melting point temperature to the brazing temperature of 600 ° C.

According to a tenth aspect of the present invention, in the invention according to any one of the first to eighth aspects, the composition of the flux mixture is 70 to 90% by weight of K ₂ SiF _6.
And a brazing flux mixture of aluminum member is AlF ₃ of 10 to 30 wt%.

The flux mixture of the present invention not only cleans the oxide film on the metal surface and prevents re-oxidation, which is the function of the conventional flux, but also forms Al by Al precipitated from K ₂ SiF ₆ and Al by the aluminum member. Since the -Si eutectic brazing material phase is formed and the connecting portions of the aluminum members are brazed, it is desired to increase the amount of Si that becomes the brazing material phase.

In the flux mixture, K ₂ SiF ₆ is 90
When the content is not less than% by weight, the precipitated Si increases, but unreacted Si that does not react with Al precipitated from the aluminum member remains, and a black or brown residue caused by the unreacted Si is present, which disadvantageously impairs the appearance. is there. Further, when K ₂ SiF ₆ in the flux mixture is 70% by weight or less,
The amount of Si precipitated from the flux mixture decreases, and Al
-Si eutectic brazing material phase amount is reduced, resulting in inconvenience that brazing property is deteriorated.

Further, AlF added to the flux mixture
_{When the} amount of ₃ is increased, the residue such as black color is reduced and the molten flux has a clean appearance. However, when 30% by weight or more of AlF ₃ is added to the flux mixture, it precipitates from K ₂ SiF ₆ which is the other composition. The amount of Si is extremely reduced, the amount of the Al-Si eutectic brazing material phase is reduced, and brazing cannot be performed. Further, the addition of AlF ₃ was
When the content is less than 10% by weight, a favorable melting point drop of the flux mixture cannot be obtained, so that Si precipitated from the flux mixture does not sufficiently react with Al precipitated from the aluminum member, and black or black due to unreacted Si is generated. The brown residue remains, causing a problem that the brazing property is reduced and the appearance is impaired.

In the present application, 70% to 90% by weight of K ₂ SiF ₆ and 10% to 30% by weight of A
By using IF3 as a flux mixture, unreacted S
It is possible to prevent the generation of i and generate a sufficient Al-Si eutectic brazing material phase to obtain good brazing properties.

According to an eleventh aspect of the present invention, in the invention according to any one of the first to tenth aspects, a part of the fluoride in the mixture is ZnF ₂ , CaF ₂ , Cs
It is a flux mixture for brazing aluminum members, which is at least one of fluorides of F, NaF, KF and ZrF ₄ .

As described above, a part of the fluoride which is the composition of the flux mixture is replaced with ZnF ₂ , CaF ₂ , CsF, N
Even when replacing with at least one of the fluorides of aF, KF and ZrF ₄ , it is possible to lower the melting point of the flux mixture and improve the reactivity of the precipitated Si.

According to the twelfth aspect of the present invention, a flux mixture containing a non-corrosive silicon fluoride compound and a fluoride is applied to the surface of a connecting portion of an aluminum member and heated in a non-oxidizing atmosphere. And the Si in the mixture
And then reacting with Al of the aluminum member to generate a brazing material phase that becomes a liquid phase of Al-Si eutectic, and in the method of brazing an aluminum member for connecting the connecting portions of the aluminum member, A brazing method for an aluminum member, wherein a binary eutectic compound comprising 10% by weight or more and 30% by weight or less of aluminum fluoride and potassium fluoride is added to the flux mixture.

Conventionally, a brazing sheet in which a brazing material layer is coated on a core material or a brazing material is applied to an aluminum member to connect the connecting portions of the aluminum member. For example, when an aluminum member is formed using a brazing sheet, the brazing material layer coated on the surface of the brazing sheet melts, and a difference in the brazing material layer occurs in assembling the member, which limits the degree of freedom in design.

According to this embodiment, the connecting portions of the aluminum members can be joined together by the flux applied for cleaning the oxide film on the surface of the aluminum members and preventing re-oxidation. Reduction is possible. Further, since there is no occurrence of an error corresponding to the brazing material layer unlike the brazing sheet, it is possible to improve the degree of freedom in design.

The method of the present invention comprises the step of adding 10% by weight to a flux mixture containing a silicon fluoride compound and a fluoride as a composition.
By adding a binary eutectic compound consisting of aluminum fluoride and potassium fluoride of 30% by weight or less,
By lowering the melting point of the flux mixture, the reactivity of Si precipitated from the flux mixture is improved, and the amount of Al and Al-Si eutectic brazing material phase precipitated from the aluminum member is increased to improve the brazing property. Made it possible to obtain. Further, by improving the reactivity of Si precipitated from the flux mixture, it is possible to reduce the black or brown residue caused by unreacted Si and obtain a brazing material phase having good brazing properties and appearance. .

According to a thirteenth aspect of the present invention, a flux mixture containing a non-corrosive silicon fluoride compound and a fluoride is applied to the connection surface of an aluminum member and heated in a non-oxidizing atmosphere. To precipitate Si in the mixture, and then react with the surface of the aluminum base material to obtain A.
In the aluminum brazing method for producing a brazing material phase to be an l-Si eutectic liquid phase and joining the connection portions of the aluminum members, the flux mixture is made of 60% by weight or less of a metal and / or an alloy. This is a method for brazing an aluminum member having a configuration to which a mixture is added.

As described above, according to the method of the present invention, the connection portions of the aluminum members can be joined to each other by using the flux applied for cleaning the oxide film on the member surface and preventing re-oxidation. Therefore, it is possible to reduce the manufacturing cost and improve the degree of freedom in design.

When a mixture of a metal and / or an alloy of 60% by weight or less is added to a flux mixture composed of a silicon fluoride compound and a fluoride, the metal-Si eutectic solder may be formed by the metal and the precipitated Si in the mixture. Since the material phase is formed, the amount of the generated brazing material phase increases, and unreacted S
In order to reduce i, it is possible to perform brazing having a good appearance with reduced black residue.

According to a fourteenth aspect of the present invention, a flux mixture comprising a non-corrosive silicon fluoride compound and a fluoride is applied to the surface of a connecting portion of an aluminum member and heated in a non-oxidizing atmosphere. And the Si in the mixture
Is precipitated, and then reacted with Al precipitated from the aluminum member, to generate a brazing material phase that becomes an Al-Si eutectic liquid phase, and in the aluminum brazing method for joining the connecting portions of the aluminum member, The flux mixture to which a mixture of 40% by weight or less of a metal and / or alloy and a binary eutectic compound of 10% to 30% by weight of aluminum fluoride and potassium fluoride are added. This is a brazing method for aluminum members.

As described above, according to the method of the present invention, the connection portions of the aluminum members can be joined to each other by using the flux applied for cleaning the oxide film on the member surface and preventing re-oxidation. It is possible to reduce costs and improve design flexibility.

Further, a flux mixture comprising a silicon fluoride compound and a fluoride is mixed with a mixture comprising 40% by weight or less of a metal and / or an alloy and 10% to 30% by weight of aluminum fluoride and potassium fluoride. When the eutectic compound is added, the presence of the metal in the mixture and the decrease in the melting point of the flux mixture due to the addition of the covalent compound increase the reactivity of Si precipitated from the flux mixture, reduce unreacted Si, It is possible to prevent the generation of residues such as black due to unreacted Si, increase the amount of the brazing material phase composed of Al-Si eutectic and metal-Si eutectic, and obtain good brazing properties. .

According to the fifteenth aspect of the present invention, in a heat exchanger formed from an aluminum member, a flux mixture containing a non-corrosive silicon fluoride compound and a fluoride is added in an amount of 10% by weight to 30% by weight. % Or less of a binary eutectic compound consisting of aluminum fluoride and potassium fluoride, the flux mixture is applied to the surface of a connecting portion of an aluminum member constituting a heat exchanger, and heated in a non-oxidizing atmosphere. Depositing Si in the mixture,
The heat exchanger has a configuration in which an Al-Si eutectic brazing material phase is generated by reacting with a surface of an aluminum base material constituting a heat exchanger, and connection portions of the aluminum members are connected to each other.

The invention described in claim 16 of the present application provides a heat exchanger formed of an aluminum member, wherein a metal and / or alloy is added to a flux mixture containing a non-corrosive silicon fluoride compound and a fluoride. Is added, the flux mixture is applied to the surface of the connecting portion of the aluminum member constituting the heat exchanger, and heated in a non-oxidizing atmosphere to precipitate Si in the mixture, and the heat exchanger is heated. A heat exchanger having a configuration in which a metal-Si eutectic brazing material phase and an Al-Si eutectic brazing material phase are generated by reacting with a surface of an aluminum base material to be formed, and connecting portions of the aluminum members are connected to each other.

The invention described in claim 17 of the present application is directed to a heat exchanger made of an aluminum member, wherein a flux mixture containing a non-corrosive silicon fluoride compound and a fluoride is added in an amount of 40% by weight or less. A mixture composed of a metal and / or an alloy and a binary eutectic compound composed of 10% to 30% by weight of aluminum fluoride and potassium fluoride are added, and the flux mixture is connected to an aluminum member constituting a heat exchanger. The mixture is heated in a non-oxidizing atmosphere to precipitate Si in the mixture, react with the surface of the aluminum base material constituting the heat exchanger, and form a metal-Si eutectic brazing material phase and Al -A heat exchanger having a configuration in which a Si eutectic brazing material phase is generated and connection portions of the aluminum members are connected to each other.

Thus, a flux mixture obtained by adding a binary eutectic compound consisting of aluminum fluoride and potassium fluoride and a mixture consisting of a metal and / or an alloy to a flux mixture consisting of a silicon fluoride compound and a fluoride According to the brazing method, the addition of the mixture lowers the melting point of the flux mixture to improve the reactivity of Si precipitated from the flux mixture, and not only Al precipitated from the aluminum member, but also metals and / Or precipitated Si reacts with the metal of the alloy,
A heat exchanger capable of reducing unreacted Si, producing an Al-Si eutectic brazing filler metal phase and a metal-Si eutectic brazing filler metal phase, and securing good brazing strength by improving brazing properties. Can be obtained.

[0068]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, specific examples of the present invention will be described in detail.

In this embodiment, the aluminum material is brazed by using a mixture of a non-corrosive silicon fluoride compound and a fluorine compound.

K ₂ SiF ₆ used as the basic composition of the non-corrosive flux is represented by the following equation:
It is considered that Si was precipitated.

3K₂SiF₆+ 4Al = 3Si + 2KA
IF₄+ 2K₂AlF₅  From the above equation, it can be seen that Si in potassium fluorosilicate is a base material.
It is presumed that these precipitate on the aluminum plate.

<Experiment 1> First, a flux composed of a mixture of K ₂ SiF ₆ and AlF ₃ , which is a non-corrosive flux, was applied on an aluminum plate (3003 series).
Heated in an oven at 6000C to 610C.

FIG. 1 is a diagram showing a schematic configuration of a small tubular furnace used in the test of this example.

As shown in FIG. 1, the heating was performed with an outer diameter of 60 m.
m, a small tubular furnace 1 having an inner diameter of 54 mm and a total length of 1000 mm, and a flow rate of 3 to 5 l / min as an atmosphere in the furnace.
Of nitrogen gas was introduced. The oxygen concentration in the furnace atmosphere was 0.01% or less.

In the drawing, 2 is a test sample, 3 is an oxygen sensor, 4 is a thermocouple, 5 is a nitrogen gas inlet, 6 is a quartz tube constituting a furnace, and 7 is a heating element. Reference numeral 8 denotes a sample stage for holding the sample 2.

In this experimental example, the height was 30 mm × the width was 30
mm x 1 mm high aluminum plate (3003
System) with a K ₂ SiF ₆ and AlF ₃ flux mixture.
05 g was weighed and uniformly applied on the aluminum plate with a dispersant. In addition, as a comparison, a flux used for removing an oxide film, which is conventionally used, was similarly applied on the aluminum plate, and the flux mixture and the aluminum plate on which the conventional flux was applied were placed in a nitrogen atmosphere at 600 ° C. It heated in the inside and observed the state after heating.

As a result, the conventional flux is melted by heating, but no metal deposition is recognized from the melted flux. Unless a brazing material is separately supplied, brazing for connecting the connecting portions is performed. It was confirmed that it was not possible.

On the other hand, it was confirmed that in the flux mixture composed of K ₂ SiF ₆ and AlF ₃ , Si was precipitated at the same time that the flux mixture was melted.

FIG. 2 shows an enlarged photograph of the flux mixture after heating and melting the flux mixture composed of K ₂ SiF ₆ and AlF ₃ .

As shown in FIG. 2, it can be confirmed that gray crystals of Si were precipitated.
1 to form an Al-Si eutectic liquid phase,
Can be observed flowing along the crystal grains.

Accordingly, an Al-Si eutectic liquid phase is formed by Si precipitated from the flux mixture of K ₂ SiF ₆ and AlF ₃ and Al precipitated from the base aluminum, and this liquid phase is crystallized as a brazing filler metal phase. By converting
It can be confirmed that brazing is performed. Thus, K ₂ S
S deposited from a flux mixture of iF ₆ and AlF ₃
The eutectic mixture formed by i and Al precipitated from the aluminum member forms a brazing material phase, so that the brazing sheet coated with the brazing material layer does not need to be newly supplied or the brazing sheet coated with the brazing material layer is used. It was confirmed that the connection portions were brazed.

However, in the flux mixture composed of K ₂ SiF ₆ and AlF _3, since the melting point of K ₂ SiF ₆ itself is relatively high at 750 ° C., it is necessary to lower the melting point to a brazing temperature of about 600 ° C. , AlF ₃ must be strictly controlled.

It has also been confirmed that black or brown residues are still present in the eutectic in which the flux mixture has been melted, and there remains a problem that good brazing cannot be obtained.

Further, in order to perform good brazing, it is necessary to improve fillet forming ability and increase the amount of brazing material phase. Further, in order to obtain good brazing properties, the wettability of the base material becomes a problem, and a wide range of uniform wettability is required. <Experiment 2> First, in order to lower the melting point of the flux mixture to about 600 ° C., which is the brazing temperature, the composition of the flux mixture K ₂ SiF ₆ and AlF ₃ was changed to obtain the eutectic mixture after heating. I checked the status. Table 1 shows the results.

[0085]

[Table 1] As shown in Table 1 (1), the flux mixture does not melt unless AlF ₃ is added at all. As shown in Tables 1 (2) to (5), 10% to 40% by weight of AlF
₃ , the smaller the amount of AlF ₃ added, that is, the larger the amount of K ₂ SiF ₆ in the flux mixture,
The amount of Si precipitated from the mixture increases. On the other hand, AlF
_It can be confirmed that when the addition amount of ₃ is small, the black or brown residue that appears on the surface of the aluminum member increases.

Therefore, when the amount of AlF ₃ added is large, the appearance after melting is improved without black or brown residues, and the amount of precipitated Si is reduced.

As a result of actual observation, it was found that the amount of AlF ₃ added was 30.
% Or more, the black or brownish residue is reduced, but it can be confirmed that the Si deposition amount is reduced.

For this reason, the addition amount of AlF ₃ is set to 15 Wt% or less.
When changed within the range of 25 Wt%, no remarkable difference was observed.

Accordingly, the mixing ratio of K ₂ SiF ₆ and AlF ₃ is such that K ₂ SiF ₆ is 70 Wt% to 90 Wt%.
It is considered that about 10 Wt% to 30 Wt% of AlF ₃ is appropriate. <Experiment 3> Next, K ₂ SiF ₆ 80 Wt considered to be good
An experiment was conducted to reduce black or brown residue using a mixture having a composition of 20% by weight of AlF _{3 and} 20% by weight of AlF ₃ (hereinafter referred to as “mixture A”). In order to reduce black or brown residue deposited from the flux mixture A, a binary eutectic compound consisting of aluminum fluoride and potassium fluoride is added in a range of 10 Wt% to 30 Wt%, and the flux mixture is added to an aluminum plate. 600 ℃ on the surface
The state of the mixture after heating and melting in a nitrogen atmosphere was observed.

FIG. 3 (a) shows the state of the eutectic mixture after only the mixture A was applied to an aluminum plate and heated.
FIG. 3B shows a mixture obtained by adding 20% by weight of a binary eutectic compound composed of aluminum fluoride and potassium fluoride to mixture A (hereinafter, referred to as “mixture B”) and heating the mixture on an aluminum plate. The state of the mixture after is shown.

When comparing FIG. 3 (a) and FIG. 3 (b),
Compared to the state after heating of the mixture A consisting only of K ₂ SiF ₆ and AlF ₃ (FIG. 3A), the mixture B to which the binary eutectic compound consisting of aluminum fluoride and potassium fluoride was added was compared. In the state after the heating (FIG. 3B), it can be confirmed that although the presence of black residue is recognized at the center portion, the black residue is reduced at the outer peripheral portion. Therefore, improvement of residue removal was confirmed by adding a binary eutectic compound consisting of aluminum fluoride and potassium fluoride.

Here, the black or brownish residue observed in the mixture after heating the mixture A is the amount of Si deposited from the mixture A.
It is considered that is left unreacted. That is, it is considered that since the melting point of the mixture A is relatively high, the precipitated Si does not sufficiently react with Al of the aluminum member having a lower melting point than the mixture A, and remains as unreacted Si.

Therefore, by adding a binary eutectic compound of aluminum fluoride and potassium fluoride to the mixture A, the melting point of the flux mixture is lowered, the reactivity of the precipitated Si is improved, and the origin of the residue is reduced. It is considered that the residue is reduced because the amount of unreacted Si decreases.

The melting temperature of the binary eutectic compound consisting of aluminum fluoride and potassium fluoride is 570 ° C. to 590 ° C.
C. and the melting point of the flux mixture drops when the eutectic compound is added to mixture A. Also it includes binary eutectic compound consisting of potassium aluminum fluoride and fluoride after heating and _{melting, KAlF 4, KAlF 5 · 5H} 2 O, K 3 Al
F ₆ . It is assumed that the compound forms a compound such as AlF ₃ and participates in the eutectic brazing filler metal phase.

Here, if the amount of the eutectic compound consisting of aluminum fluoride and potassium fluoride is less than 10%, the melting point of the mixture B does not drop to the desired level. If the amount of the eutectic compound composed of aluminum fluoride and potassium fluoride is more than 30% by weight,
i The amount of precipitation was reduced and a sufficient brazing material phase was not generated, so that it was confirmed that it was not suitable for the purpose of brazing with a flux mixture.

Therefore, the amount of the binary eutectic compound of aluminum fluoride and potassium fluoride to be added to the mixture A comprising K ₂ SiF ₆ and AlF ₃ is not less than 10% by weight.
0% by weight or less seems to be suitable.

<Experiment 4> Next, using the mixture B,
The fins of the heat exchanger were brazed, and fillet formation and brazing strength were evaluated.

As an evaluation method, an aluminum plate (300
3)), a predetermined amount of the mixture B is applied, a fin material composed of 10 peaks is sandwiched between two aluminum plates coated with the flux, and fixed by a jig.
After heating for about 2 to 13 minutes, the shape of the fillet was observed.

First, the amount of flux applied to an aluminum plate as a test piece was examined.

Table 2 shows the results.

[0101]

[Table 2] 4 (1) to 4 (5) show that the amount of mixture B
in the case of changing the range of ^{g / m 2 ~200g / m 2} ,
The side view of the fillet formed between a fin material and an aluminum plate is shown.

In FIG. 4 (1) to (5), 9 is a fin material,
Reference numeral 10 denotes an aluminum plate, and 11 denotes a fillet formed by a brazing material phase.

As shown in the results of Table 2 and FIGS. 4 (1) to 4 (5), it was confirmed that as the amount of the mixture B applied increased, the fillets formed increased.

When the amount of the mixture B applied is 160 g / m ² or more, a good fillet generation amount is obtained.
It was confirmed that a fillet formation amount of less than g / m ² was not obtained.

Here, when the application amount of the flux mixture is increased, Si precipitated from the flux mixture remains unreacted, so that the residue tends to increase. In addition, it is preferable that the amount of flux applied at the time of brazing is small in terms of cost. <Experiment 5> Then, in order to reduce the amount of flux to be applied and obtain good brazing properties, a mixture comprising a metal and / or an alloy was added to mixture B, and the eutectic mixture after heating and melting was added. Was evaluated.

In this example, aluminum was used as the metal.

Table 3 shows the results obtained by adding Al at a predetermined ratio to the mixture B and observing the state of the eutectic mixture after heating and melting.

In this example, only the addition ratio of Al is shown, but Al and / or an alloy (for example, Al-Si
It is considered that similar results can be obtained for alloys.

[0109]

[Table 3] From the results shown in Table 3, it was confirmed that when the addition amount of Al and / or Al-Si alloy to be added to the mixture B is 40% by weight or less, the brazing filler metal phase can be improved.

If more than 40% by weight of Al and / or Al-Si alloy is added, the amount of precipitated Si decreases, so that the generated Al-Si eutectic and metal-Si eutectic brazing material phases are reduced. And it is difficult to obtain good brazing properties.

Here, the reason why the mixture made of the metal and / or the alloy was added to the mixture B is that Si precipitated from the flux mixture reacts with Al of the aluminum member to form Al.
Not only generates a eutectic brazing filler metal phase, but also reacts with the added metal and / or alloy metal to form a metal-Si eutectic brazing filler metal phase, thereby increasing the amount of eutectic liquid phase generated. This is to improve brazing properties.

That is, Si deposited from the flux
Is presumed to undergo a diffusion reaction with Al of the aluminum member to form a eutectic liquid phase, and this liquid phase becomes a brazing material phase and brazing is performed, but cannot be diffused into the aluminum member at the same time. It is assumed that the precipitated Si becomes unreacted Si and residue is generated. Therefore, if a mixture comprising a metal and / or an alloy is added to the flux mixture,
Precipitated Si is preferentially metal and / or in the flux mixture.
Alternatively, it is assumed that it is possible to improve the brazing property by increasing the amount of liquid phase generated by reacting with the alloy.

The reason why the mixture of the metal and / or the alloy was added is that Al used as the metal in this example has a melting point of 660 ° C., while the melting point of the Al—Si alloy is 5 ° C.
Since the temperature was 77 ° C., the melting point of the flux mixture was lowered and the reactivity of precipitated Si was improved as compared with the case where only Al was added. <Experiment 6> Next, in order to improve the brazing property of a flux mixture obtained by adding a mixture of a metal and an alloy to the mixture B, the average particle size of the added metal and / or alloy mixture was changed, and the mixture was heated and melted. The state of the eutectic mixture later was confirmed.

In this example, the average particle size was 45 μm to 15 μm.
0 μm, average particle size of 45 μm and average particle size not exceeding 10 μm, Al and Al-S having three kinds of average particle sizes
The state of the eutectic mixture after heating and melting was observed using the mixture composed of the i-alloy.

In this example, as in Experiment 1, 30
0.05 g of a flux mixture obtained by adding a mixture of Al and an Al-Si alloy of each average particle size to an aluminum plate (3003 series) having a size of 30 mm x 30 mm x 1 mm in height is applied on the aluminum plate, The mixture was heated in a nitrogen atmosphere at ℃, and the state of the eutectic mixture after heating was observed.

Table 4 shows the results.

[0117]

[Table 4] As shown in Table 4, when the average particle size of Al and the Al—Si alloy was 45 μm or less, the wettability after heating was good.

FIG. 5A shows a state of a eutectic mixture of a flux mixture to which aluminum and an Al—Si alloy having an average particle size of 45 μm or less are added, and FIG. 5B shows aluminum and Al having an average particle size of 45 μm to 150 μm. 4 shows a micrograph of a eutectic mixture after heating of a flux mixture to which a -Si alloy has been added.

As shown in FIG. 5A, the average particle size was 45 μm.
m and a flux mixture to which Al and an Al-Si alloy are added, the precipitated Si and Al are completely dissolved,
It can be confirmed that a perfect eutectic structure was formed and good wettability was obtained. On the other hand, in the flux mixture to which Al and the Al-Si alloy having an average particle size of 45 μm to 150 μm were added, Si and Al were not completely eutectic, and unreacted Si, Al
Can remain, and it can be confirmed that unevenness has been caused in wetness.

Therefore, if the average particle size of the metal and alloy mixture added to the flux mixture is 45 μm or less,
It was confirmed that it was possible to form a complete eutectic liquid phase with the precipitated Si to improve brazing properties.

That is, when the average particle size of the metal or alloy is 45 μm or less, the surface area reacting with the precipitated Si is increased, and the diffusion speed of Si is accelerated. A Si eutectic brazing filler metal phase is formed.

Incidentally, Al having an average particle size of 10 μm or less and / or
Alternatively, when an Al-Si alloy was added, the wettability was good, but it was confirmed that black or brown residues were present in the eutectic mixture. This is presumably due to the fact that the average particle size was reduced, resulting in an increase in the amount of oxygen contained in the metal and alloy mixture.

If the average particle size is 45 μm or more, the oxygen content is about 0.3 to 0.4%, but the average particle size is 10 μm.
m or less, the oxygen content is about 1%.

As described above, when the average particle size is small, the reactivity increases because the surface area is increased and the diffusion rate of Si is promoted. On the other hand, when the average particle size is small, it is contained in the mixture. Due to the increased oxygen content, the average particle size of the metal and / or alloy mixture added to the flux mixture is 45%.
It is preferable that the thickness is not more than μm and the oxygen content is not more than 1%. <Experiment 7> Further, those having an average particle size of 45 μm to 150 μm, an average particle size of 45 μm, and an average particle size of not more than 10 μm, 3
A mixture comprising Al and / or an Al-Si alloy having various average particle sizes was added to the mixture B to confirm the brazing property of the flux mixture.

As shown in FIG. 6, in the brazing property confirmation test of this example, a certain amount of flux was applied to the entire surface of an aluminum plate (3003 series) 12 and another aluminum plate (3003 series) 13 Is heated at 600 ° C. to 610 ° C. for about 12 to 13 minutes, and then the mixture state after melting and the aluminum plate 1
The state of formation of the fillet 14 formed between 2 and 13 was confirmed.

In this test, in order to reduce the amount of applied flux as much as possible, the mixture B was added to 0.04 g, and
And a total of 0.05 g (100 g / m ² ) of a flux mixture to which 0.01 g of a mixture of an Al—Si alloy was added was applied.

The results are shown in Table 5 and FIG.

[0128]

[Table 5] FIGS. 7 (1) to 7 (4) show that the flux mixture having the composition shown in Tables 5 (1) to 5 (4) was applied to a reverse T-shaped test piece and the temperature was 600 ° C.
It is a photograph which shows the state of the eutectic mixture after heating.

As shown in Table 5 and FIG. 7, a brownish residue was clearly observed on the test piece to which only the mixture B was applied (Table 5 (1), FIG. 7 (1)), and the average particle size was 45 μm to 1 μm.
Specimens coated with 50 μm or less of Al and Al-Si alloy had reduced black residues compared to test specimens coated with mixture B alone, but black residues were observed around the eutectic liquid phase. (Table 5 (4), FIG. 7 (4)).

Al and Al—S having an average particle size of 45 μm or less
It was confirmed that the test piece coated with the i-alloy had no black residue and exhibited good wettability (Tables 5 (2) and (3), and FIGS. 7 (2) and (3)).

FIG. 8 shows that the average particle size of Al is 45 μm or less.
FIG. 4 is an enlarged view of a fillet portion formed between test pieces (aluminum plates) combined in an inverted T-shape coated with an Al-Si alloy.

As shown in FIG. 8, by adding a mixture of Al and an Al—Si alloy having an average particle size of 45 μm or less to the mixture B by 20% by weight, a flux mixture application amount of 0.05 g (100 g / m ² ) was obtained. And good fillet-forming ability.

Therefore, the flux mixture obtained by adding Al and the Al—Si alloy to the mixture B has a coating amount of 100 g / m 2.
^{In step 2} , a flux mixture consisting of mixture B alone was added to 160
The same good fillet as in the case of coating with g / m ² or more was formed, and it was confirmed that the brazing property was improved. <Experiment 8> Further, the fillet formation area at each application amount of the mixture B and the mixture C obtained by adding Al and an Al-Si alloy having an average particle size of 45 μm or less to the mixture B was confirmed.

As in Experiment 8, an aluminum plate (300
3) apply a predetermined amount of mixture B or mixture C over the entire surface,
A test piece in which another aluminum plate (3003 series) was combined in an inverted T-shape thereon was heated at 600 ° C. to 610 ° C. for about 12 to 13 minutes, and the formed fillet area was measured.

The results are shown in FIG. FIG. 9 shows the change in the applied amount of each flux mixture and the fillet area.
Indicates the fillet area formed when the flux mixture B is applied in different amounts, and C in the figure indicates the fillet area formed when the flux mixture C is applied in different amounts.

As shown in FIG. 9, when the mixture B and the mixture C were compared, it was confirmed that the mixture C had a larger fillet area and exhibited better brazing properties due to an increase in fillet forming ability. did it.

That is, in the mixture C obtained by adding a metal and / or an alloy to the mixture B, the Si precipitated from the flux mixture becomes a eutectic liquid phase preferentially with the metal in the flux mixture, and the brazing material is formed. It is considered that the fillet forming ability is larger than that of the mixture B to which the metal and / or the alloy is not added because the amount of the phase is increased, and good brazing property is exhibited. <Experiment 9> Next, the mixture B was added in an amount of 20% by weight and an average particle size of 4%.
Al and Al-S of 5 μm or less (oxygen content 1% or less)
Using the mixture C to which the i-alloy mixture was added, the fins of the heat exchanger were brazed, and fillet formation and brazing strength were evaluated.

As an evaluation method, an aluminum plate (300
100 g / m ² of the mixture C was applied to 3), a fin material composed of 10 peaks was sandwiched between two aluminum plates coated with the flux, and fixed with a jig.
After heating at 〜610 ° C. for about 12 to 13 minutes, the shape of the fillet was observed.

The results are shown in FIG. FIG.
FIG. 4 is a side view showing a state of a fillet 4 formed between a eutectic brazing filler metal phase of a mixture C and the aluminum plate 2.

As shown in FIG. 10, the flux mixture C
100 g / m ² and brazing the fins,
It was confirmed that the same good fillet-forming ability as that when the flux mixture B was applied at 160 g / m ² or more (see FIGS. 4 (4) and 4 (5)). Although not shown in the drawings, it was confirmed that when the fin was brazed using the mixture C, good brazing properties in appearance without black or brown residues were observed.

<Experiment 10> Next, the brazing strength when brazing was performed using the flux mixture C was evaluated.

As an evaluation method, an aluminum plate (300
100 g / m ² of mixture C at 100 g / m ^{2 was} applied to 3), and a fin material composed of 10 peaks was sandwiched between two aluminum plates coated with the flux, and fixed with a jig, at 600 ° C. Heating was performed at ６610 ° C. for about 12 to 13 minutes, and the fins and the aluminum plate brazed were subjected to a destructive test.

As a result of the destruction test, the fin and the aluminum plate to which the flux mixture C was applied were destroyed by 100% fin material, and no destruction of the brazing portion connecting the fin and the aluminum plate was confirmed. Confirmed that there was no problem.

On the other hand, as a comparative test, the mixture B was applied to an aluminum plate, and fins were similarly brazed, and then a destructive test was carried out. It was confirmed that the brazing part to be connected was destroyed.

<Experiment 11> Next, after heating and melting a mixture D obtained by adding only a metal and alloy mixture to mixture A without adding a binary eutectic compound comprising a mixture of aluminum fluoride and potassium fluoride to mixture A. Of the eutectic mixture was confirmed.

In this example, as in Experiment 1, the vertical
100 g / m ^{2 of} a mixture D obtained by adding Al and an Al-Si alloy having an average particle size of 45 μm or less to a mixture A to a mixture A was applied to an aluminum plate (3003 series) having a size of 30 mm × width 30 mm × height 1 mm. Then, the mixture was heated in a nitrogen atmosphere at 600 ° C., and the state of the eutectic mixture after heating was observed.

As a result, the state of the eutectic mixture after the heating and melting of the mixture D is different from the state of the eutectic mixture of the mixture C obtained by adding Al and an Al—Si alloy to the mixture B composed of aluminum fluoride and potassium fluoride. It was almost the same, and it was confirmed that the precipitated Si and Al formed a perfect eutectic liquid phase and exhibited good wettability.

In the eutectic mixture D, no black or brownish residue was confirmed, and it was confirmed that a eutectic brazing material phase having a good appearance was formed.

When the amount of the metal and / or alloy added to the mixture A is 60% by weight or more, the amount of Si precipitated from the flux mixture is reduced, so that the amount of the eutectic brazing filler metal phase is reduced and a good brazing alloy is obtained. It is difficult to obtain the attachment property.

As described above, the binary eutectic compound composed of aluminum fluoride and potassium fluoride of a predetermined composition, or the mixture composed of metal and / or alloy is added to the mixture A, which is a conventionally used non-corrosive flux. Or a binary eutectic compound comprising aluminum fluoride and potassium fluoride having a predetermined composition and a metal and / or
When the mixture comprising the alloy is added, the reactivity of the precipitated Si and the base metal Al or the metal in the additive mixture and the Si precipitated from the flux mixture is improved due to the melting point drop of the flux mixture, and the residue of the unreacted Si is caused by unreacted Si. Prevent generation,
It is possible to obtain a brazing material phase that is good in appearance.

Also, the addition of the binary eutectic compound consisting of aluminum fluoride and potassium fluoride lowers the melting point of the flux mixture, so that the Si precipitated from the flux mixture and the base material Al, or the reaction between the precipitated Si and metal, Thus, the precipitated Si becomes completely eutectic, the fillet forming ability is improved, and a eutectic brazing material phase having a predetermined brazing strength can be provided, whereby the brazing property is improved.

According to the flux mixture of the present invention, it is possible to perform brazing in which predetermined brazing strength and fillet forming ability are ensured, similarly to the case where aluminum members are joined using a brazing sheet.

When brazing is performed by the brazing method using the flux mixture of the present invention, the brazing sheet which has been conventionally used is brazed at the connection portion by melting the coated brazing material layer. Although there was a problem that the range in which the dimensional change was caused by the melting of the brazing material layer was large, according to the flux mixture of this example, the range of the dimensional change due to the melting of the brazing material layer was reduced, and strict dimensional control became unnecessary. The degree of freedom in design, yield, and ease of assembly are improved.

Further, since it is possible to perform brazing using a flux which has been conventionally used for removing an oxide film on a metal surface, cost can be reduced.

In this example, Al and Al-S
A mixture of i-alloys was added, but some or all of Al
Instead of Zn, Sn or In, the sacrificial anode effect can be improved, and the corrosion resistance of the brazed portion can be improved.

It is also assumed that the addition of Sr improves the reactivity of precipitated Si by the action of making the flux mixture finer.

Further, when Zn or silver (Ag) is added,
It has been confirmed that the addition of a small amount of from 10% by weight to 10% by weight improves fillet forming ability.

When Ni or Ti is added instead of Al, the surface film can be stabilized, and the corrosion resistance and heat resistance of the brazed portion can be improved. Furthermore, when a mixture of Al and Si is added in addition to the Al-Si alloy, the eutectic brazing material phase may be increased and the brazing property may be improved similarly to the addition of the Al-Si alloy.

It is also possible to replace part of the silicon fluoride compound serving as the basic composition with NaSiF ₆ or ZnSiF ₆ .

[0160] Further, for the purpose of melting point depression of the silicon fluoride compound has been added AlF _3, a portion of AlF _3,
It is also possible to form a mixture flux instead of ZnF or LiF.

Further, when the flux mixture of this example is used for brazing the connection portion of each member of the heat exchanger 15 (FIG. 11) formed of an aluminum member or the like, the degree of freedom of design, the yield, and the assemblability can be improved. Is improved, and brazing with predetermined brazing strength and good fillet forming ability can be performed. In this example, a stacked heat exchanger is illustrated, but the present invention is not limited to this example, and a serpentine type heat exchanger and other components formed using an aluminum member can be manufactured.

[0162]

As described above, the present invention relates to a flux mixture comprising a non-corrosive silicon fluoride compound and a fluoride, wherein the flux mixture is applied to the surface of a connecting portion of an aluminum member. Heating in a non-oxidizing atmosphere, a flux mixture for brazing an aluminum member connecting the connecting portions, wherein the flux mixture is formed from aluminum fluoride and potassium fluoride in an amount of 10% by weight or more and 30% by weight or less. This is a flux mixture for brazing aluminum members to which a binary eutectic compound is added.

As described above, a binary eutectic compound consisting of aluminum fluoride and potassium fluoride is added to the flux mixture as a composition of the non-corrosive silicon fluoride compound and the fluoride in an amount of from 10% by weight to 30% by weight. By using the added flux mixture, the connecting portions of the aluminum members can be joined together without using a brazing sheet in which a brazing material layer is coated on a core material.

When the connection of the aluminum members is performed by the flux mixture, the difference in the dimensional change due to the melting of the brazing material layer does not become large unlike the brazing sheet.
Improves design flexibility, yield, and ease of assembly. Further, since the brazing can be performed with the flux mixture without supplying the brazing material, the cost can be reduced.

When a binary eutectic compound consisting of aluminum fluoride and potassium fluoride is added to the flux mixture, the melting point of the flux mixture decreases, and the reactivity of Si precipitated from the flux mixture improves.
Unreacted Si is reduced, and a black or brown residue that has been confirmed when melting a flux mixture consisting of a silicon fluoride compound and a fluoride that does not contain a binary eutectic compound consisting of aluminum fluoride and potassium fluoride is reduced. The aluminum members can be brazed in a good appearance, and the brazing property can be improved.

The present invention is a flux mixture in which a mixture comprising a metal and / or an alloy is added to a flux mixture containing a non-corrosive silicon fluoride compound and a fluoride.

The Si precipitated from the flux mixture is
It reacts not only with Al in the aluminum member but also with metals in the metal and alloy mixture, thereby improving the reactivity of precipitated Si, reducing unreacted Si, which was conventionally considered to be a cause of residues such as black, and reducing black and the like. The appearance can be improved by preventing the generation of residues. Further, by improving the reactivity with Si precipitated from the flux mixture, Al-
By increasing the brazing filler metal phase composed of the Si eutectic and the metal-Si eutectic, it is possible to obtain sufficient fillet forming ability.

The present invention also relates to a flux mixture for brazing an aluminum member, wherein a mixture of a metal and / or an alloy of 60% by weight or less is added to a flux mixture containing a silicon fluoride compound and a fluoride. It is.

As described above, by adding a mixture of a metal and / or an alloy of 60% by weight or less to a flux mixture comprising a silicon fluoride compound and a fluoride, a brazing material formed by a reaction with Al of an aluminum member. Reacts not only with the phase but also with the added metal and / or alloy metal to form a brazing filler metal phase, thereby reducing the amount of unreacted Si, increasing the amount of brazing filler metal phase, and leaving black and other residues due to unreacted Si. The appearance can be improved by preventing the occurrence of the occurrence, and the brazing property can be improved.

The present invention also relates to a flux mixture containing a non-corrosive silicon fluoride compound and a fluoride as a composition, wherein a mixture comprising 40% by weight or less of a metal and / or an alloy and 10% by weight or more and 30% by weight or less. It is a flux mixture for brazing aluminum members to which a binary eutectic compound consisting of the following aluminum fluoride and potassium fluoride is added.

As described above, the flux mixture consisting of the silicon fluoride compound and the fluoride is mixed with the mixture consisting of the metal and / or alloy of 40% by weight or less and the mixture of 10% by weight or more and 3% or more.
When a binary eutectic compound consisting of aluminum fluoride and potassium fluoride of 0% by weight or less is added, the metal of the mixture and the melting point of the flux mixture due to the addition of the eutectic compound decrease, thereby causing precipitation from the flux mixture. S
i) to reduce the amount of unreacted Si, to prevent the generation of residues such as black due to unreacted Si,
By increasing the amount of the brazing material phase composed of the eutectic and the metal-Si eutectic, it is possible to secure the brazing strength and obtain good brazing properties with a large fillet forming ability.

Further, the present invention is a flux mixture for brazing aluminum members, wherein the metal or alloy has an average particle size of 45 μm or less.

As described above, when the average particle size of the metal or alloy added to the flux mixture containing the silicon fluoride compound and the fluoride is 45 μm or less, the surface area that reacts with Si precipitated from the flux mixture is determined. And the diffusion of Si is promoted, so that the reactivity of precipitated Si is improved, and a metal-Si eutectic brazing filler metal phase is formed at a low melting point, so that brazing properties can be improved. In addition, it is possible to prevent the generation of a residue such as black due to unreacted Si, and obtain good brazing properties. When the average particle size of the metal and alloy is 45 μm or less and the oxygen content in the metal and alloy is 1% or less, the reactivity of precipitated Si is not hindered by the oxygen content.

The composition of the flux mixture is silicon fluoride compound of K ₂ SiF ₆ , and fluoride is A
lF is a brazing flux mixture of aluminum members is _three.

As described above, when the flux mixture having the composition of K ₂ SiF ₆ and AlF ₃ is applied to the surface of the connecting portion of the aluminum member and heated in a non-oxidizing atmosphere, Si precipitates from the flux mixture, Forming Al and Al-Si eutectic brazing filler metal phase from aluminum member,
In addition to cleaning the oxide film, which is the object of the conventional flux coating, the connecting portion of the aluminum member is formed by the above-mentioned Al-Si.
Connected by eutectic brazing filler metal phase.

As described above, according to the present invention, the brazing of a heat exchanger or the like using an aluminum member can be performed by using the flux mixture or the brazing method using the flux mixture. Therefore, the degree of freedom in design, the yield, and the ease of assembly can be improved, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a view showing a schematic configuration of a small tubular furnace used for a test according to a specific example of the present invention.

FIG. 2 shows a test piece of K ₂ SiF _{6 according} to an embodiment of the present invention.
FIG. 4 is a view showing a state after a flux mixture composed of AlF ₃ and AlF ₃ is applied and heated and melted.

3 (a) shows a state of a eutectic mixture after applying only mixture A to an aluminum plate and heating the mixture, and FIG. 3 (b) shows aluminum fluoride in mixture A according to an embodiment of the present invention. FIG. 4 is a view showing a state after a mixture B to which a binary eutectic compound composed of manganese and potassium fluoride is added at 20% by weight is applied to an aluminum plate and melted by heating.

FIG. 4 relates to a specific example of the present invention, wherein (1) to (5) are:
The coating amount of the mixture B is 40 g / m ²~ 200g / m²Range of
Formed between fin material and aluminum plate when changed by surrounding
It is a side view which shows the state of the fillet performed.

FIG. 5 shows (a) an average particle size of 4 according to an embodiment of the present invention.
The state of the eutectic mixture after the heating of the flux mixture to which 5 μm or less of aluminum and the Al-Si alloy are added is shown, and the heating after the heating of the flux mixture to which the aluminum and the Al-Si alloy having the average particle size of 45 μm to 150 μm are added in FIG. 3 is a photomicrograph showing a state of a eutectic mixture of FIG.

FIG. 6 is a test piece according to a specific example of the present invention in which an aluminum material (3003 series) is combined in an inverted T-shape for a brazing property test.

FIG. 7 relates to a specific example of the present invention, wherein (1) to (4) are:
Aluminum B and aluminum alloy having an average particle size of 20% by weight were added to the mixture B alone and the mixture B, respectively.
It is a figure which shows the state of a eutectic mixture after performing the brazing property test using the aluminum plate of a letter.

FIG. 8 shows a mixture B containing 20% by weight of aluminum and Al—S having an average particle size of 45 μm or less according to an embodiment of the present invention.
It is an enlarged view of the fillet part formed between the test pieces (aluminum material) combined with the inverted T shape which applied the flux mixture which added the i alloy.

FIG. 9 is a diagram showing a change in the application amount of each flux mixture and a change in fillet area according to a specific example of the present invention.

FIG. 10 is a side view showing a state of a fillet formed by a eutectic brazing material phase of a mixture C between a fin and an aluminum plate according to a specific example of the present invention.

FIG. 11 is a front view of a heat exchanger in which an aluminum member is brazed by using the flux mixture according to a specific example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Small tubular furnace 2 Test sample 3 Oxygen sensor 4 Thermocouple 5 Nitrogen gas inlet 6 Quartz tube 7 Heating element 8 Sample stand 9 Fin 10 Aluminum plate 11 Fillet 12 Aluminum plate 13 Aluminum plate 14 Fillet 15 Heat exchanger B Mixture B C mixture

Claims (17)

[Claims] 1. A flux mixture comprising a non-corrosive silicon fluoride compound and a fluoride, wherein the flux mixture is applied to the surface of a connecting portion of an aluminum member and heated in a non-oxidizing atmosphere. A flux mixture for brazing an aluminum member connecting the connecting portions, wherein a binary eutectic compound comprising 10% by weight or more and 30% by weight or less of aluminum fluoride and potassium fluoride is added to the flux mixture; A flux mixture for brazing aluminum members. 2. A flux mixture comprising a non-corrosive silicon fluoride compound and a fluoride, wherein the flux mixture is applied to the surface of a connecting portion of an aluminum member and heated in a non-oxidizing atmosphere. A flux mixture for brazing an aluminum member, wherein the mixture of metals and / or alloys is added to the flux mixture. 3. The flux mixture according to claim 2, wherein a mixture of a metal and / or an alloy in an amount of 60% by weight or less is added to the flux mixture containing the silicon fluoride compound and the fluoride as a composition. Flux mixture for brazing aluminum parts. 4. A flux mixture comprising a non-corrosive silicon fluoride compound and a fluoride, wherein the flux mixture is applied to the surface of a connecting portion of an aluminum member and heated in a non-oxidizing atmosphere. A brazing flux mixture for an aluminum member connecting the connecting portions, wherein the flux mixture contains 40% by weight or less of metal and / or
Or a mixture comprising an alloy and at least 10% by weight to 30% by weight
A flux mixture for brazing aluminum members, wherein a binary eutectic compound comprising the following aluminum fluoride and potassium fluoride is added. 5. The brazing method according to claim 2, wherein the metal is at least one of aluminum, zinc, tin, indium, nickel, titanium, and phosphorus. For flux mixture. 6. The flux mixture for brazing aluminum members according to claim 2, wherein the alloy is an Al—Si alloy powder. 7. The metal or alloy has an average particle size of 45.
The flux mixture for brazing an aluminum member according to any one of claims 2 to 6, wherein the flux mixture is not more than μm. 8. The metal or alloy having an average particle size of 45.
The flux mixture for brazing aluminum members according to any one of claims 2 to 7, wherein the oxygen content in the mixture comprising the metal and the alloy is 1% or less. 9. The method according to claim 1, wherein the silicon fluoride compound as the composition of the flux mixture is K ₂ SiF ₆ , and the fluoride is AlF _3.
A flux mixture for brazing aluminum members according to any one of claims 1 to 7. 10. The composition of the flux mixture is 70
90 wt% of _K 2 SiF ₆ and 10 to 30% by weight of A
brazing flux mixture of aluminum members of the according to any one of claims 1 to 8, characterized in that a lF _3. 11. The method according to claim 1, wherein a part of the fluoride in the flux mixture is at least one of fluorides of ZnF ₂ , CaF ₂ , CsF, NaF, KF and ZrF _4. 10. The flux mixture for brazing aluminum members according to any one of 10 above. 12. A flux mixture containing a non-corrosive silicon fluoride compound and a fluoride as a composition is applied to the surface of a connecting portion of an aluminum member, and heated in a non-oxidizing atmosphere to remove Si in the mixture. The method according to claim 1, further comprising reacting the aluminum member with Al of the aluminum member to form a brazing material phase that becomes an Al-Si eutectic liquid phase, and brazing the aluminum member to connect connecting portions of the aluminum member. A method for brazing an aluminum member, comprising adding a binary eutectic compound of aluminum fluoride and potassium fluoride in an amount of 10% by weight or more and 30% by weight or less to a mixture. 13. A flux mixture containing a non-corrosive silicon fluoride compound and a fluoride as a composition is applied to the surface of a connecting portion of an aluminum member, and heated in a non-oxidizing atmosphere to remove Si in the mixture. After the precipitation, the aluminum alloy is reacted with Al of the aluminum member to generate a brazing material phase that becomes an Al-Si eutectic liquid phase. A brazing method for an aluminum member, wherein a flux mixture to which a mixture of a metal and / or an alloy is added is used. 14. A flux mixture containing a non-corrosive silicon fluoride compound and a fluoride as a composition is applied to the surface of a connecting portion of an aluminum member, and heated in a non-oxidizing atmosphere to remove Si in the mixture. After the precipitation, the aluminum alloy is reacted with Al of the aluminum member to generate a brazing material phase that becomes an Al-Si eutectic liquid phase. To 40% by weight of metal and / or
Or a mixture comprising an alloy and at least 10% by weight to 30% by weight
A brazing method for an aluminum member, comprising using a flux mixture to which a binary eutectic compound consisting of aluminum fluoride and potassium fluoride is added. 15. A heat exchanger formed from an aluminum member, wherein a flux mixture containing a non-corrosive silicon fluoride compound and a fluoride has a composition of 10% to 30% by weight of aluminum fluoride and fluoride. A binary eutectic compound made of potassium is added, and the flux mixture is applied to the surface of a connection part of an aluminum member constituting a heat exchanger, and heated in a non-oxidizing atmosphere to precipitate Si in the mixture. A heat exchanger which reacts with a surface of an aluminum base material constituting the heat exchanger to generate an Al-Si eutectic brazing filler metal phase and connects connecting portions of the aluminum members. 16. A heat exchanger formed from an aluminum member, wherein a mixture comprising a metal and / or an alloy is added to a flux mixture comprising a non-corrosive silicon fluoride compound and a fluoride, The mixture is applied to the connection surface of the aluminum member constituting the heat exchanger and heated in a non-oxidizing atmosphere to precipitate Si in the mixture and react with the surface of the aluminum base material constituting the heat exchanger. A heat exchanger wherein a metal-Si eutectic brazing filler metal phase and an Al-Si eutectic brazing filler metal phase are generated, and the connecting portions of the aluminum members are connected to each other. 17. A heat exchanger formed from an aluminum member, wherein a flux mixture comprising a non-corrosive silicon fluoride compound and a fluoride is mixed with a metal mixture containing not more than 40% by weight of a metal and / or
Or a mixture comprising an alloy and at least 10% by weight to 30% by weight
A binary eutectic compound consisting of the following aluminum fluoride and potassium fluoride is added, and the flux mixture is applied to the connection portion surface of an aluminum member constituting a heat exchanger, and heated in a non-oxidizing atmosphere, Si in the mixture is precipitated and reacted with the surface of the aluminum base material constituting the heat exchanger to form a metal-Si eutectic brazing filler metal phase and an Al-Si eutectic brazing filler metal phase, thereby connecting the aluminum members. A heat exchanger wherein the parts are connected to each other.