JPS60130463A - Brazing method of aluminum material - Google Patents

Abstract

PURPOSE:To eliminate material corrosion after brazing by dipping an Al material into a treating soln. prepd. by suspending K2AlF2 powder therein and adding F and K to said soln. to form the integrated layer and chemical conversion treated layer of K2AlF5 to the part to be brazed and subjecting the material to brazing thereafter. CONSTITUTION:A material to be brazed which is an Al material is dipped in a treating sonl. which is suspended therein with K2AlF5 powder and contains F and K to integrate the K2AlF5 powder to the desired part to be brazed and at the same time to form a chemical conversion treated film consisting of the K2AlF5 formed by the chemical reaction of the Al of the Al material and F, K. At least the desired part to be brazed of the material to be brazed is heated and is joined by the brazing material. The brazing using the flux which does not corrode the Al material and the brazing material after brazing is thus made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for brazing aluminum thread materials at desired portions using a brazing material.

Recently, due to the need to reduce the weight of heat exchangers such as radiators for automobiles, aluminum and aluminum alloy materials and Ae thread materials have been developed.

I've started producing it. In order to finish Ae yarn material into a radiator or the like, at least a method for bonding the materials together is required. As for the joining method, brazing is the most suitable in terms of work efficiency and the form of connection that can be obtained.

Conventionally, aluminum-silicon (Ad-Silicon), which has a slightly lower melting point than the material, has been used as a brazing material for brazing A// materials.
8i) Eutectic public gold is mainly used. Further, in order for the brazing filler metal to bond well with the material, it is necessary to remove dirt such as an oxide film existing on the surface of the material. To remove this dirt, flux is supplied to the brazing section along with the brazing material.

The fluxes used include zinc chloride, chloride)
There are mixed substances of metal chlorides such as Jium.

However, when the chloride-based substance is used as a flux, the flux remaining in the brazing part after the brazing process is
It may corrode L-based materials or brazing filler metals. Therefore, after brazing, it was necessary to thoroughly wash the product to remove the flux. Also.

Al thread materials are susceptible to pitting corrosion due to chlorine and the like. In order to suppress this as much as possible, zinc is diffused onto the surface of the material to form a sacrificial corrosion layer. It is necessary to carry out an extra step of attaching the zinc to the surface of the Al-based material in advance, making the pretreatment step for brazing complicated.

Therefore, the present inventors conducted research on a brazing method that uses a flux that does not cause corrosion of A/system material pipes, and as a result, they came up with the present invention.

An object of the present invention is to provide a brazing method using a flux that does not corrode the Al thread material and the brazing material after brazing.

υ The third invention (hereinafter referred to as the first invention) according to the present application is made by suspending potassium pentafluoroaluminate (LA#F) powder, and adding Ar yarn material to a treatment solution containing fluorine and potassium. By immersing the body in the brazing process, the A/F and powder are accumulated in the desired part, and the aluminum of the A// material and the fluorine are combined. , a dipping process to form a chemical conversion layer made of 4AlFG produced by a chemical reaction with potassium, and brazing involves heating at least a desired part of the body, and joining the desired part with a brazing material. A method for brazing Al thread materials is characterized in that it comprises the following steps:

According to the first invention, AlF is added to the surface of the A// material.
Since the chemical conversion treatment layer No. 6 is formed, the "wettability" with the A/system material pipe treatment solution is good, so K, AlF
When the powder is covered with braze, the braze on the body tends to accumulate in the desired part. Further, since the chemical conversion treatment layer acts as a flux during brazing, the flow of the brazing material is improved, and defective parts such as missing parts of the brazing material are less likely to occur at the joint during brazing.

The second invention according to the present application (hereinafter referred to as the second invention) is
K, A/F11/ powder is suspended, and fluorine,
A7?The over-brazing is performed on the body by immersing the over-brazing body made of Afi-based material in a treatment solution containing potassium and zinc.A7? In addition to accumulating FB powder, the brazing is caused by a substitution reaction between the aluminum of the Ad thread material and the zinc, which is produced by the chemical reaction between the metallic zinc deposited on the surface of the body and the aluminum, fluorine, and potassium. Brazing of aluminum-based materials is a method in which the body is heated, and the desired parts are joined using a brazing material.

According to the second invention, 2A47 is applied to the surface of the Al thread material.
Formation of a coating layer consisting of F/1 and metal zinc, and 2A4
Brazing of F6 powder can be carried out at the same time by accumulating it in a desired part.

Since the coating layer has good "wettability" with the processing solution, the L2AlF8 powder is easily accumulated in a desired part during brazing. In addition, the above-mentioned coating layer acts as a flux during the brazing process, and metal zinc
! Diffuse on the surface of the thread material.

sacrificial rot ftJ- can be formed. As a result, the resulting brazed body has a well-brazed joint and has an excellent effect of inhibiting pitting corrosion.

The following two inventions will be explained in detail.

When used in the invention according to the present application, the A4F powder acts as a flux when brazing or joining thread materials. K, A/F, begins to partially melt at a temperature of about 560°C. After the melting, AlF
has the property of removing the oxide film on the surface of the A/thread material and having no effect on the aluminum itself. K2
There are several methods for synthesizing A/F6, examples of which are as follows.

One is to add aluminum fluoride (klF) powder to an aqueous solution of potassium fluoride (KF) and leave it at room temperature for a long time, or leave it at a temperature below 1o (o￥C) for about an hour. This is a method of ripening.

KF&C contains a small amount of sodium fluoride (N
aF) + 7 Fu transformation! J f ram (L!F), 7
fluoride cuff m-7= There is no problem even if it contains dium, etc. others.

There is no problem even if small amounts of alkali metals such as Os and Rb and alkaline earths such as 0rz are included. Another method is to dissolve 1 mole of aluminum salt such as aluminum hydroxide in an aqueous solution of either 5 moles of fluorine, acid (, [), or 2 moles of potassium hydroxide (KOH). , when neutralized with the other aqueous solution, fine particles of 2 ANF b are generated in the mixed aqueous solution. The above methods are all wet methods and have the advantage of being very simple and not necessarily requiring operations such as heating.

9. In the present invention, "brazing" refers to a body made of aluminum or aluminum alloy material processed into a desired shape, which is assembled into a plurality of parts so that they can be brazed together.

The above aluminum alloy metal RU, aluminum (A#)
The main components are silicon < SI) and copper (C!u).
, -vygay (Mn), zinc (Zn), titanium (
Ti), ram(Or), shift: *=t7m(
Zr).

-1 8 ------- An alloy to which at least one type of magnesium (Mg) or the like is added.

Specifically, JIS 3005 material, 1050 material, 7
There are aluminum associations such as 072 material.

Furthermore, as another aluminum alloy material.

An alloy with a melting point as low as 10 to i0 (0-1'C) is coated on the surface of the Al thread material, such as aluminum-silicon (A#
-8i) It may be coated with a eutectic alloy as a brazing material. Specifically, there is a material in which the surface of JI86oo5 material is clad with 4646 material (eg, BA12P0).

If it is plate-shaped, it is called a praising sheet. When this material is used for at least one component of the desired part, there is no need to supply a filler metal during the brazing process.

First, the first invention will be explained.

In the dipping step of the first invention, the brazing body made of the above A/thread material is immersed in a treatment solution, and the A/F coating layer is applied to the surface of the brazing body by chemical conversion treatment. At the same time as forming, brazing is a process of accumulating 15AlF powder in desired areas.

The treatment solution contains fluorine and potassium.

Moreover, it is a suspension of K, A/jF5 powder.

The AlF powder suspended in the treatment solution may have a diameter ranging from colloidal particles of approximately α1 to (L5 μm) to sand grains of approximately 1FF. It is desirable that the powder be attached to the desired part from the viewpoint of easy accumulation.The amount of suspension of the powder is preferably about 20 to 80f with respect to the solution 14.In this case, K
, AfilI', an appropriate amount of surfactant may be added to improve the dispersibility of the powder.

On the other hand, there are several methods for preparing the treatment solution containing fluorine and potassium. To give an example of this, first of all, potassium hydrogen fluoride (IIF
, ) and zinc fluoride (ZnF, ) in water.

Another method is to dissolve potassium fluoride (KF) and hydrogen fluoride (fIF) in water.

These aqueous solutions contain potassium at a concentration of 0.01 to 1 mol/l.

It is desirable that the molar ratio of fluorine to potassium is 1 to 10. When the concentration of the aqueous solution is adjusted within the above range, KiAfiF is formed on the surface of the aluminum material.
A coating layer consisting of , can be efficiently formed.

The treatment solution in the first invention is the above aqueous solution.

241F powder was suspended in the above.

To perform brazing, the body is immersed in the treatment solution prepared as described above. Then, the oxide film existing on the surface of the A/F thread material that makes up the body is destroyed, and aluminum, potassium, and fluorine react chemically to form a coating layer of A/F. , Brazing, which is the part where materials are assembled, is done at the desired location.

KJA/Fs is deposited and accumulated. At this time, a coating layer of [2AlF] is formed on the surface of the 47-based material, which improves its wettability with the processing solution.

K4A$F powder tends to settle on the surface, and when A4 thread material is brazed, it also tends to penetrate into gaps in desired areas.

41 A sufficient amount of c2hBx on the surface of the yarn material
When the solder is formed and the AlF powder has sufficiently penetrated into the desired area, the solder is gently pulled out of the treatment solution. After that, it is dried to remove moisture. In brazing, a coating layer consisting of A/F is formed on the surface of the body by chemical conversion treatment, and furthermore, A/F powder suspended in a processing solution is accumulated.

In other words, the surface of the A/yarn material becomes 2A due to the chemical conversion treatment.
As a result of eF6 being generated and the surface being slightly roughened, A/F powder tends to accumulate even though it is suspended, and a large amount of A
It is possible to accumulate IF.

The brazing process is applied to the body after the above-mentioned dipping process, and the brazing process is added to the body. For brazing, if there is no brazing material, it is necessary to supply it to the desired part. In this case, as a method of supplying the brazing material, it is preferable to supply a rod-shaped, linear or powdered brazing material, such as A,/-8i eutectic alloy, along a desired portion. The brazing filler metal may be previously subjected to the chemical conversion treatment according to the present invention. In addition, when using powdered brazing filler metal, add K! to the f3 suspension water beforehand. A/F,
A mixture of K, AlFs powder and brazing filler metal is suspended together with the AC-based material in which the powder is accumulated, and the brazing filler metal is melted by heating, such as by placing the powder into a heating furnace. brazing is to attach them to each other. The heating temperature in the brazing process is preferably below the melting point of the Al-based material and above the melting point of the brazing material. The heating atmosphere is most preferably a non-oxidizing atmosphere, but may also be an atmosphere containing a small amount of oxygen.

During the main brazing process, K and A4F act as fluxes to remove the oxide film on the A/thread material.

However, it does not react with aluminum of the Al thread material. As a result, the "wettability" between the brazing material and the Afi thread material becomes good, and a sound brazing joint can be formed.

The details of the phenomenon in the actual brazing process are not clear, but it is thought to be first-order. First, when the temperature rises to about 560°C, a part of [2A/F, as a flux, begins to melt. The melted flux reacts on the surface of the Al thread material and removes the oxide film on the Al thread material.

Furthermore, when the temperature is raised, the brazing filler metal or brazing material applied to the surface of the Al-based material melts and comes into contact with the surface of the Ag-based material without an oxide film. A//The surface of the material has good "wettability" with the brazing material, and the brazing material spreads between the members at desired locations.

When the brazing filler metal has sufficiently spread in the brazing area,
When cooled, the brazing filler metal solidifies and joins the parts together.A
//The materials are brazed.

In the present invention, 2A/F8 has the ability to strongly remove the oxide film on the back surface of A/ type materials, and has excellent properties as a flux in that it does not react with A// materials. . Therefore, defects such as pinholes are less likely to occur in the brazing material forming the joint.

Additionally, flux residues present at or near braze joints do not corrode the A// material because they are substantially insoluble in water.

Next, the second invention will be explained.

In the immersion step in the second invention, the brazing body is immersed in a treatment solution as in the first invention, and the Al-based material is treated, and the K! Brazing the AeFs powder is a process of accumulating it in a desired area.

The treatment solution in the second invention is the treatment solution in the first invention further containing zinc. There are several methods for preparing the treatment solution containing fluorine, potassium, and zinc. One of them is potassium hydrogen fluoride (KHF) and zinc fluoride (Zn).
There is a method of dissolving F, ) in water.

There is a law.

The processing solution in the second invention is as described above in these aqueous solutions! It is a suspension of A/F. Concentrations of fluorine and potassium in the treatment solution and A, 5F.

The amount of suspended powder is preferably the same as in the first invention, and the larger the amount of zinc, the better, and the larger the amount, the faster the rate of precipitation of metallic zinc deposited on the surface of the Al-based material, so it is desirable. Specifically, it is preferably about 0.05 to α1 mole -15 times.

Additionally, hydrogen fluoride was added to the treatment solution to adjust the pH to 6.
It is desirable to set it to about 4. The reason for creating a mixed aqueous solution with hydrogen fluoride is that by adding fluorine,
In addition to increasing the molar ratio of fluorine, the purpose is to make the treatment solution acidic to increase the amount of zinc dissolved and to promote the reaction with fluorine, potassium, and aluminum.

The brazing body is immersed in the treatment solution. The immersion time is not generally determined depending on the concentrations of potassium, fluorine, and zinc and the temperature of the solution, but is preferably about 5 to 20 minutes, for example. A
// When the body of a brazing material made of a material is immersed, the zinc present in the form of ions undergoes a substitution reaction with metallic aluminum to become metallic zinc, which is generated on the surface of the Al-based material. Furthermore, aluminum, which has been replaced with zinc and becomes ions, combines with potassium and fluorine in the processing solution.

K4A/F, and adheres to the surface of the Al thread material together with the metal zinc. That is, it is possible to form a coating layer on the surface of the Al thread material in which LAAFs as a flux and metallic zinc for forming a sacrificial corrosion layer are finely and uniformly mixed. Once this coating layer is formed, the "wettability" between the A7/yarn material and the treatment solution will improve, and the braze covered with the treatment solution will easily penetrate into small gaps in the body. It can easily get into the cracks. As a result, the coating layer on the body is 2A.
4F, K, AdF・
Even in the case of powder and turbid water, it is possible to accumulate a large amount of 2A/F and at the same time to precipitate metallic zinc for forming a sacrificial corrosion layer.

What is the amount of metallic zinc produced on the body surface of brazing?

A//Metallic zinc is 1.5-5F per unit surface area of material
//rd is desirable because post-process brazing forms a sacrificial corrosion layer in the process, and complete brazing forms a joint. There is no problem in brazing even if the amount of metal zinc and x, A6F is greater than the above range.

Next, in the brazing process, the body is heated by placing it in a heating furnace in the same way as in the first invention, and the brazing process in the second invention is performed so that the melted brazing material can be brazed as desired. Brazing forms a joint and diffuses metallic zinc into the surface of the A/based material to form a zinc diffusion layer as a sacrificial corrosion layer.

The heating temperature in the main brazing process is preferably below the melting point of the Al thread material and above the melting point of the brazing material, since the melting point of the brazing material is generally higher than the melting point of zinc. Most preferably, the heating atmosphere is a non-oxidizing atmosphere, but an atmosphere containing a small amount of oxygen may also be used.

The actual brazing process is performed using metallic zinc, K2AI!
Although the behavior of F6 is not clear, it is thought to be of 9th order.

When the brazing process is applied, the temperature of the brazing body begins to rise. When the temperature reaches approximately 420°C, the zinc fixed to the surface of the aluminum alloy begins to melt.

When the temperature further increases to about 560°0, K,
A part of A4FB began to melt, and AI! The reaction occurs on the surface of the yarn material, and the oxide film that remained during heating or from the beginning is removed. Originally, when a chemical conversion treatment step is performed, the oxide film is small, so even a small amount of LA/F as in the present invention is sufficient to remove the oxide film as a flux. Also, molten zinc.

Zinc diffuses from the surface of the Al-based material into the interior of the material, forming a zinc diffusion layer. The braze then melts and comes into contact with the surface of the A/yarn material. Since the oxide film has been removed from the Al thread material, it has good wettability with the brazing material, and the brazing material penetrates into the gaps between the brazing parts. At this time due to the presence of zinc.

The fluidity of the brazing filler metal is further improved.

A portion of the molten zinc also diffuses into the brazing material.

As zinc diffuses into place.

Once the brazing material has sufficiently penetrated into the brazing section, if it is cooled, the brazing material will solidify and bond the A/thread materials together, forming a joint.

It is desirable that the above-mentioned zinc diffusion layer has a thickness of about 0.1811 mm and the amount of zinc on the surface thereof is about 5 wt%, but even less than this has the effect of inhibiting corrosion.

In the brazing of the obtained product, there are almost no defects such as Binho μ in the brazing material forming the joint. Furthermore, even if the product is subjected to the corrosive action of chlorine, the zinc diffusion layer on its surface is selectively corroded.

Corrosion does not easily progress to the center of the A/yarn material, i.e.
It has the feature of being able to suppress so-called pitting corrosion, which penetrates the material. As a result, the life of the product is increased.

Also, the resulting braze does not corrode the A/yarn material since the 7 lux residue on the surface of the product is essentially insoluble in water.

Conversely, these residues have a greater affinity for water than Al-based materials. Therefore, for example, water condensed on the fins of a heat exchanger for an air conditioner can easily move toward the water tray. As a result, the flow of air in the narrow air passages of the heat exchanger is not obstructed by condensed water, so that heat exchange is performed smoothly, resulting in advantages such as improved efficiency of the heat exchanger.

Examples will be described below.

Example 1 1 mo-20 per 11 hydrogen fluoride water with a concentration of 4N
-- Dissolve aluminum hydroxide (Al(OH), ).

A potassium hydroxide (KOH) aqueous solution having a concentration of 10N was added to this to adjust the hydrogen ion concentration (PH) to 3 to 7. Then, the aqueous solution began to become cloudy and became flurry-like. The slurry is dried and mainly contains 2A.
(A powder consisting of <F5 fine particles was obtained.

On the other hand, thickness 2111M, size 3 crri x 3 crr
Prepare the aluminum alloy plate 1 (3QQ3 material) of i and the so-called plating sheet 2, which is an aluminum alloy plate of the same size and made of 3005 material (BA12PC material) with 4643 material clad on the 9 surface. The parts were combined into a single-shape shape as shown in FIG.

On the other hand, 11 aqueous solutions containing a total of 0.27 potassium hydrogen fluoride (KHF2) were prepared, and added to the above, A$
F.

2011 powder was added and stirred to prepare a treatment solution in the first invention.

The brazing body was immersed in the treatment solution and then pulled out.

The surface of the body of the brazed body had a whitish tinge, and the treatment solution was uniformly attached to the desired part of the brazed body.

After drying this, heat it up in an electric furnace with a nitrogen atmosphere,
For brazing, the desired parts were observed. As a result, as shown in Fig. 2, the 4343 material flows down from the brazing sheet 2 as a brazing material, and the brazing penetrates uniformly into the desired areas, forming a good fillet part 4t and plating with the aluminum metal plate 1. ging sheet 2 was firmly joined. K,A
Although dF was kept in an Al-based humid atmosphere for a long period of time, no corrosion due to flux was observed.

Example 2 2A/F powder was obtained in the same manner as in Example 1.

Furthermore, potassium fluoride (F) was added at 1 mol/l.

Hydrogen fluoride (HF) at 3 mol/1, zinc fluoride at 0.
8) Prepare an aqueous solution containing V/l.

2klF8 powder was added to the above and thoroughly stirred to obtain a treatment solution according to the second invention.

On the other hand, in over-brazing, the aluminum passes through the tube of the heat exchanger for the temporary air conditioner used in automobiles, and as a result, the fins connected to the tube are cooled, so the fins are cooled. The air passing around the area is cooled. 30 tubes
03 material, the fins are molded using plating sheets.

For the brazing process, the body was immersed in the treatment solution for 1 minute, then pulled out and dried. During brazing, a coating layer is formed on the surface of the body in which metal zinc and AgF2 are finely mixed, and K! AI! Ii'11 powder is uniformly attached to the contact area between the fin and the tube! A
/F, a lot of powder was accumulated.

Thereafter, brazing was performed by heating at 620 DEG C. for 5 minutes in a nitrogen atmosphere electric furnace larger than that used in Example 1.

As a result, approximately 5,000 brazing locations were determined at desired locations -, -,
The brazing metal entered No. 23-, and a good brazing joint was formed, and a zinc diffusion layer was formed on one surface to serve as a sacrificial corrosion layer.

Brazing is chlorinated on the heat exchanger that has undergone the process) IJum 5
An accelerated corrosion test was conducted by spraying a wt% aqueous solution.

As a result, the zinc diffusion layer was corroded, but pitting corrosion did not occur. As a comparative example.

A heat exchanger made of the same material was treated with a treatment solution similar to that prepared in Example 1, and after brazing, a similar corrosion test was conducted at the same time. Pitting corrosion occurred from the surface to the inside of this heat exchanger.

From the above, according to the present invention, the amount of A and IF+1 deposited becomes uniform and large.

Good flow of the filler metal and good defect-free brazing can produce joints. Also, in the second invention.

Furthermore, it has the advantage that zinc for forming a sacrificial corrosion layer can be simultaneously integrated with A/F.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are shown in Example 1--2, respectively.
4-- is a perspective view showing the shape of the body and the brazing situation. 1... Aluminum alloy plate 2 @ 111111 image plating sheet 5... Desired part for brazing 4---... Fillet Patent applicant Toyota Central Research Institute Co., Ltd. (2 others)

Claims (6)

[Claims] (1) Potassium pentafluoroaluminate (K, A
By dipping the brazing body made of aluminum thread material into a treatment solution containing fluorine and potassium, the brazing body is formed by suspending 1F, ) powder, and the brazing body is brazed onto the desired part of the body. In, A/F. The immersion process involves accumulating the powder and forming a chemical conversion layer consisting of A, 5F, which is produced by a chemical reaction between the aluminum of the aluminum material and the fluorine and potassium, and the brazing process is performed at least on the body. A method for brazing aluminum-based materials, characterized in that brazing consists of the steps of heating a desired part, and joining the desired part with a brazing material. (2) A method for brazing aluminum-based materials according to claim (1), wherein the aluminum-based material is an aluminum alloy material coated with an aluminum-silicon eutectic alloy as a brazing material. (3) The above treatment solution is made by suspending 20 to 200 g of A/F powder in 11 water, and α0
1 to 1 mole, fluorine to potassium molar ratio of 1 to 1
Claim No. (1) or (2) containing 0
) Brazing method for aluminum-based materials. (4) Potassium pentafluoroaluminate (K, A
/FB) consists of suspended powder and fluorine. By immersing the soldering body made of an aluminum-based material in a treatment solution containing potassium and zinc, the soldering results in the accumulation of 4AfiFs powder on the body and the combination of the aluminum of the aluminum-based material and the zinc. The brazing coating is produced by a chemical reaction between metal zinc precipitated on the surface of the body and aluminum, fluorine, and potassium through a substitution reaction. A method for brazing aluminum-based materials, which is characterized by heating the body and applying the brazing material to the desired part during brazing. (5) A method for brazing aluminum-based materials according to claim (4), wherein the aluminum-based material is an aluminum alloy material coated with an aluminum-silicon eutectic alloy as a brazing material. (6) The above treatment solution contains K, AfiFs in water 11
It is made by suspending 20 to 200 g of powder, and also contains 0.01 to 1 mole of potassium, 0.01 to 0.2 mole of zinc,
A method for brazing aluminum-based materials according to claim 4 or 5, wherein the solution contains fluorine in a molar ratio of 1 to 10 to potassium.