JP2737803B2 - Aluminum brazing sheet for vacuum brazing - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an aluminum alloy brazing sheet for vacuum brazing, and more particularly, to a brazing sheet excellent in vacuum brazing properties and free from brazing. Is provided.

[Conventional technology and its problems]

Normally, brazing of aluminum or aluminum alloy is performed by fixing an aluminum or aluminum alloy member to be joined through a brazing material having a lower melting point than aluminum or the like to form an assembly. This is performed by heating to a temperature lower than the melting point of the aluminum or aluminum alloy member to be obtained. And as brazing material alone, generally Al
-Si-based alloy is used, and its shape is plate-like, linear or powdery, or as another form, aluminum or aluminum alloy core material is coated with brazing material of the above composition It is used as a bonding material (hereinafter referred to as a brazing sheet).

The brazing method is a flux brazing method using a flux for removing an oxide film on the surface of a member to be brazed, a method of brazing in a non-oxidizing atmosphere using a non-corrosive flux, without using a flux. Vacuum brazing is commonly used in which the assembly to be joined is placed in a vacuum and brazed and heated.

FIG. 1 shows a laminated evaporator formed by the vacuum brazing method. This is a structure in which fins (1) and passage forming sheets (2) and (2 ') formed of brazing sheets forming refrigerant passages (3) and (3') are alternately laminated and joined by vacuum brazing. is there. Here, a fin material having a thickness of about 0.1 mm is used, and a brazing sheet having a thickness of about 0.6 mm is used as a passage forming sheet. In such an evaporator, the fin material includes Zn, I
Alloys added with n, Sn, etc. are used. The brazing sheet uses JIS 3003 alloy as the core material and has
A clad Si-Mg-based brazing alloy is generally used.

FIG. 2 shows a serpentine evaporator. This is done by attaching fins (1) between extruded multi-hole tubes (4) bent in a meandering shape, attaching connectors (5) and (5 ') to both ends of the extruded multi-hole tubes (4), and vacuum brazing. They are joined. And the fin material has a thickness of 0.16
5mm thick, 22m wide for extruded multi-hole tube
m and a thickness of about 1.0 mm are used. In such an evaporator, a brazing sheet in which the Al-Mn-based alloy is used as a core material for the fin material and an Al-Si-Mg-based brazing alloy is clad is used, and JIS 3003 alloy, Al
-Cu-based alloys and Al-Cu-Mn alloys are used.

What is common to these brazing sheets is that the brazing material contains Mg. This is because Mg evaporates during heating for brazing and enables vacuum brazing by the getter function.

By the way, when a brazing furnace is used for a long time for the vacuum brazing, the degree of vacuum is inevitably reduced due to contamination in the furnace. In such a case, a brazing phenomenon occurs, in which the wettability of the brazing is reduced and brazing cannot be performed without forming a brazing fillet. Further, when brazing the inside of the hermetically sealed structure as in the evaporator shown in FIG. 1, there is a problem that the brazing properties often differ between the inside and the outside.

[Means for solving the problem]

In view of this, the present invention has been developed for a brazing sheet suitable for vacuum brazing.

That is, one of the brazing sheets of the present invention is formed by cladding Al alloy brazing material on both sides or one side of an Al or Al alloy core material, and in a brazing sheet to be subjected to vacuum brazing, 6 wt% or more and 20 wt% or less of Si. And 0.6 wt% or more and 1.8 wt% or less of Mg, and the balance of Al and inevitable impurities
Using a Si-Mg alloy brazing material, Mg ₂ Si particles having a size of 2 μm or more existing inside the brazing material are 540 in the middle of vacuum brazing and heating.
The number is 300 / mm ² or more at ° C.

Another one of the brazing sheet of the present invention is Al or
Brazing sheet made by cladding Al alloy brazing material on both sides or one side of Al alloy core material and used for vacuum brazing, Si of 6wt% or more and 20wt% or less and 0.6wt% or more and 1.8wt%
% Mg or less, with the balance being Al and unavoidable impurities
An Al-Si-Mg alloy brazing material is used, and the surface film thickness of the brazing material is 750 A (angstrom) or less at 530 ° C. during heating by vacuum brazing.

Still another one of the brazing sheets of the present invention is:
Brazing sheet made by cladding Al alloy brazing material on both sides or one side of Al or Al alloy core material, and being used for vacuum brazing, 6% to 20% by weight of Si and 0.6% by weight or more
Using an Al-Si-Mg alloy brazing material containing 1.8 wt% or less of Mg and the balance of Al and unavoidable impurities, Mg ₂ Si particles having a size of 2 μm or more inside the brazing material are heated by vacuum brazing. At 540 ° C. in the middle, the thickness is 300 / mm ² or more, and the surface coating thickness of the brazing material is 750 A (angstrom) or less at 530 ° C. in the middle of heating by vacuum brazing.

And another one of the brazing sheet of the present invention is formed by cladding an Al alloy brazing material on both sides or one side of an Al or Al alloy core material, and in a brazing sheet provided for vacuum brazing, 6 wt% or more and 20 wt% or less. 1.8w with more than 0.6wt% of Si
An Al-Si-Mg alloy brazing material containing t% or less of Mg and 0.3 wt% or less of Fe, the balance being Al and unavoidable impurities is used, and Mg ₂ Si having a size of 2 μm or more existing inside the brazing material is used. The particles are characterized by being 300 particles / mm ² or more at 540 ° C. during heating by vacuum brazing.

And also another one of the brazing sheet of the present invention,
Brazing sheet made by cladding Al alloy brazing material on both sides or one side of Al or Al alloy core material, and being used for vacuum brazing, 6% to 20% by weight of Si and 0.6% by weight or more
Contains 1.8 wt% or less of Mg and 0.3 wt% or less of Fe, with the balance being Al
And an Al-Si-Mg alloy brazing material consisting of unavoidable impurities, and the thickness of the surface coating of the brazing material during the vacuum brazing heating.
It is characterized by being 750 A (angstrom) or less at 530 ° C.

Furthermore, another one of the brazing sheets of the present invention is formed by cladding Al alloy brazing material on both sides or one side of an Al or Al alloy core material, and in a brazing sheet to be subjected to vacuum brazing, 6 wt% or more and 20 wt% or less. 1.8w with more than 0.6wt% of Si
Using an Al-Si-Mg alloy brazing material containing Mg of not more than t% and Fe of not more than 0.3 wt%, the balance being Al and unavoidable impurities, Mg ₂ Si having a size of 2 μm or more existing inside the brazing material. It is characterized in that the particles are 300 particles / mm ² or more at 540 ° C during vacuum brazing and the surface coating thickness of the brazing material is 750A (angstrom) or less at 530 ° C during vacuum brazing. Things.

(Operation)

First, the configuration of the brazing sheet of the present invention will be described.

The tempering of the alloy of the core material of the brazing sheet is not particularly specified. Depending on the member to be used, for example, JIS 3003 alloy, an alloy to which Mg, Cu, Zn, Sn, In or the like is added, or a pure aluminum-based alloy in consideration of thermal conductivity may be used as appropriate.

The composition of the brazing material is 6 wt% (hereinafter, wt% is simply described as%)
An Al-Si-Mg alloy containing at least 20% of Si and 0.6% or more and 1.8% or less of Mg or an Al-Si-Mg alloy containing 0.3% or less of Fe is used.

Si in the brazing material is an additive element that lowers the melting point of the alloy and enables brazing. And if the content is less than 6% or 20
%, The melting point of the braze is increased and the brazing properties are reduced.

Mg in the brazing material evaporates during brazing and has an effect of improving the degree of vacuum by a getter function and a function of destroying an oxide film by evaporation. If the content is less than 0.6%, the above-mentioned effects do not sufficiently occur and the brazing property is reduced, and
When the temperature exceeds brazing, the Mg-based oxide film increases on the contrary during the heating for brazing, thereby deteriorating the brazing property.

Next, when the Fe content is specified to be 0.3% or less in the present invention, a brazing material having particularly excellent brazing resistance is obtained. In other words, during brazing heating, an oxide film grows on the surface of the brazing material before Mg in the brazing material starts to evaporate, and at this time, Fe has an effect of promoting the growth of the film. . However, if the content of Fe exceeds 0.3%, the growth amount of the film becomes large, so that the film is not sufficiently broken at the time of evaporating Mg, the wettability of the solder is reduced, and the solder breaks easily.

The above is the composition of the brazing alloy according to the present invention.
Can be added from 0.01% to 0.2%. In this case, Bi has the function of improving the flowability of brazing, promoting the evaporation of Mg, and facilitating the breakage of the film. Bi
If the amount of addition is less than 0.01%, the above effect is not sufficient,
If it is more than 2%, the rollability of the brazing material is reduced, and it is difficult to produce a brazing sheet.

The alloy of the present invention contains 0.2% or less of C as an inevitable impurity.
u, 0.3% or less of Zn added for the purpose of improving corrosion resistance, Ti and B added as a grain refiner at the time of casting, and Mn, In, Sn added for the purpose of improving brazing properties, etc. , Cr, Z
Elements such as r, Ca, V, Pb, Ag, Be and the like may be contained in less than 0.05%.

Such brazing alloy is clad on one or both sides, but the coverage is not particularly defined. What is necessary is just to cover the required amount for every member.

The above is the alloy composition of the brazing sheet. In the present invention, the Mg ₂ Si particles are further limited as described above.

This may be because the Mg in the brazing material normally solid solution Mg, Al-Mg intermetallic compound is present in the form of such Mg ₂ Si particles, Mg ₂ Si particles which have a great influence on the wax out of Is found by the inventors. That is, Mg, Al
-Mg present as an Mg-based metal compound evaporates from the relatively early stage of vacuum brazing and improves the degree of vacuum by the getter effect.However, since these are present finely throughout the braze, they explode when the braze is melted. Evaporates and has no power to destroy the film. On the other hand, when the Mg ₂ Si particles remain until the time of the melting of the wax, the Mg ₂ Si particles cause explosive evaporation of the Mg at the time of the melting and break the film on the surface. Therefore, at 540 ° C. during vacuum brazing, the number of Mg ₂ Si particles of ₂ μm or more existing in the brazing material is limited to 300 particles / mm ² or more.

Here, the reason for the particles at 540 ° C. during the heating by vacuum brazing is that the amount of particles immediately before melting of the braze is a problem. The reason why the particle size is set to 2 μm or more is that particles having a particle size of less than 2 μm at 540 ° C. do not have a sufficient explosive force to destroy a surface film at the time of brazing. Even if the number is less than 300 pieces / mm ² , the breaking force is insufficient.

In addition, the Mg ₂ Si particles can be used for the brazing sheet at 10 ^-5 Tor.
r Heat to 540 ° C at a heating rate of 30 ° C / min.
After quenching with nitrogen gas, the cross section was polished and observed with a reflection electron image of a scanning electron microscope.Particles that appeared darker than the matrix in the reflection electron image were judged as Mg ₂ Si particles, and image analysis was performed. Is used to determine the equivalent circle diameter.

It should be noted that the brazing material having such a particle distribution can be obtained by controlling the homogenizing treatment conditions in the production process, the rolling ratio, and the like.

In the present invention, the brazing material surface coating thickness of the brazing sheet is 750 A at 530 ° C. during vacuum brazing.
(Angstrom) Determined as follows. It is to mainly oxide film and surface film here, 30 ℃ / min. 530 ℃ at a heating rate of the brazing sheet in level of 10 ^-5 Torr vacuum degree
After quenching with nitrogen gas, the area of about 4 mm diameter was measured by glow discharge spectroscopy, and converted by step measurement after measurement.

This surface film is closely related to the above-mentioned brazing phenomenon. That is, when the film thickness is 750A (angstrom) or less, Mg evaporation occurs from around 530 ° C during brazing heating, but Mg evaporation there occurs to make the film porous from the entire surface of the film. Breaks down finely by rapid evaporation and improves brazing properties.

On the other hand, when the film thickness at 530 ° C exceeds 750A (angstrom), the evaporation of Mg occurs mainly from the weaker part of the film during brazing heating, and conversely, the other part of the film grows thicker and stronger. I do. Mg evaporates rapidly during the melting of the braze, but the evaporation at that time occurs mainly in the same place as during the heating, so that the film on the braze surface is not sufficiently destroyed, and the wettability with the wax is reduced, Cutting occurs.

Since the surface coating thickness of such a brazing material is about 1000 A (angstrom) in the conventional brazing sheet manufacturing process, in order to obtain the coating thickness limited in the present invention,
Cleaning with an alkali may be sufficiently performed during the production.

In the present invention, as described above, 2 μm existing inside the brazing material is used.
m ₂ or more Mg ₂ Si particles are present at 300 / mm ² or more at 540 ° C during vacuum brazing and when the surface coating thickness of the brazing material is 750A (angstrom) or less at 530 ° C during vacuum brazing. Although there are certain limitations, each of them has properties superior to those of the conventional material, but when both are used together, more excellent brazing properties are obtained.

〔Example〕

 Hereinafter, the present invention will be described specifically with reference to Examples.

An aluminum alloy core material and a brazing material having the compositions shown in Table 1 were used, and these were combined to produce a brazing sheet having the structure shown in Table 2 (sheet thickness: 0.6 mm, cladding ratio: 15%, double-sided cladding). The tempering of the brazing sheet is O material (annealed material). The Mg ₂ Si particles and the film on the surface in the table were measured by the methods described above.

The Mg ₂ Si particles were adjusted according to casting conditions and homogenization treatment conditions, and the surface coating was adjusted variously by performing alkali washing with a NaOH solution before and after final annealing.

Next, individual cup-shaped articles (6) as shown in FIG. 3 are formed from such brazing sheets, and cup-shaped articles (6) produced from these same brazing sheets are shown in FIG. And 100 cup brazing tests were performed. The heating conditions in the brazing test were 10 min. After reaching 600 ° C. at a heating rate of 30 ° C./min. The ultimate vacuum is about 5 × 10 ⁻⁵ Torr. At the same time, a 500 ml beaker was placed over the cup in the same furnace for brazing, and a brazing test was performed assuming that the degree of vacuum was reduced. Table 3 shows the number and appearance of the cups that had been heated and the appearance of brazing.

As is evident from Table 3, the brazing sheet of the present invention has no wax breakage, and the surface is silver-white, exhibiting excellent characteristics. On the other hand, the characteristics of the brazing sheets of the conventional material and the comparative material are significantly reduced when heated in a beaker, particularly when the degree of vacuum is reduced.

〔The invention's effect〕

As described above, the brazing sheet of the present invention is excellent in brazing properties. In particular, even when the degree of vacuum of the brazing furnace fluctuates, no brazing occurs, and the brazing sheet has a remarkable industrial effect.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially cutaway perspective view showing an example of a laminated evaporator, FIG. 2 is a side view showing a part of an example of a serpentine evaporator, and FIG. 3 is cup brazing. It is a side view which shows the partial cross section of the laminated cup using a test. 1 fin 2,2 'passage structure sheet 3,3' refrigerant passage 4 extruded multi-hole tube 5,5 'connector 6 cup-shaped product

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-264190 (JP, A) JP-A-3-297592 (JP, A) JP-A-49-11748 (JP, A) JP-A-50- 51448 (JP, A) JP-B 53-15974 (JP, B2) JP-B 55-12355 (JP, B2) JP-B 56-22440 (JP, B2) JP-B 61-9778 (JP, B2)

Claims (6)

(57) [Claims] 1. A brazing sheet comprising an Al or Al alloy core material clad on both surfaces or one surface thereof with an Al alloy brazing material and subjected to vacuum brazing, wherein 6 wt% or more and 20 wt% or less of Si is used.
Using an Al-Si-Mg alloy brazing material containing 0.6 wt% or more and 1.8 wt% or less of Mg, the balance being Al and unavoidable impurities, and Mg ₂ Si particles having a size of 2 μm or more existing inside the brazing material. Is 300 / mm ² or more at 540 ° C during vacuum brazing heating. 2. A brazing sheet comprising an Al or Al alloy core material clad on both surfaces or one surface thereof with an Al alloy brazing material and subjected to vacuum brazing, wherein 6% by weight or more and 20% by weight or less of Si is used.
And an Al-Si-Mg alloy brazing material containing 0.6 wt% or more and 1.8 wt% or less of Mg and the balance being Al and unavoidable impurities. An aluminum brazing sheet for vacuum brazing, wherein the temperature is 750 A (angstrom) or less at ℃. 3. A brazing sheet comprising an Al or Al alloy core material clad on both surfaces or one surface thereof with an Al alloy brazing material and subjected to vacuum brazing, wherein 6% by weight or more and 20% by weight or less of Si is used.
Using an Al-Si-Mg alloy brazing material containing 0.6 wt% or more and 1.8 wt% or less of Mg, the balance being Al and unavoidable impurities, and Mg ₂ Si particles having a size of 2 μm or more existing inside the brazing material. At 300 ° C / mm ² or more at 540 ° C during vacuum brazing,
And the thickness of the surface film of the brazing material is
An aluminum brazing sheet for vacuum brazing, which is 750 A (angstrom) or less at 530 ° C. 4. A brazing sheet which is formed by cladding an Al or Al alloy core material on both surfaces or one surface thereof with an Al alloy brazing material and subjected to vacuum brazing, wherein a Si content of 6 wt% or more and 20 wt% or less.
And an Al-Si-Mg alloy brazing material containing 0.6 wt% or more and 1.8 wt% or less of Mg and 0.3 wt% or less of Fe, the balance being Al and unavoidable impurities. 2 μm
An aluminum brazing sheet for vacuum brazing, wherein the Mg ₂ Si particles are 300 particles / mm ² or more at 540 ° C. during vacuum brazing heating. 5. A brazing sheet comprising an Al or Al alloy core material clad on both surfaces or one surface thereof with an Al alloy brazing material and subjected to vacuum brazing, wherein 6% by weight or more and 20% by weight or less of Si is used.
And an Al-Si-Mg alloy brazing material containing 0.6 wt% or more and 1.8 wt% or less of Mg and 0.3 wt% or less of Fe and the balance of Al and unavoidable impurities. 750 A (angstrom) at 530 ° C during vacuum brazing
An aluminum brazing sheet for vacuum brazing characterized by the following. 6. A brazing sheet comprising an Al or Al alloy core material clad on both surfaces or one surface thereof with an Al alloy brazing material and subjected to vacuum brazing, wherein 6% by weight or more and 20% by weight or less of Si is used.
And 0.6wt% or more and 1.8wt% or less of Mg and 0.3wt% or less of Fe
Al-Si-Mg alloy brazing material containing Al and unavoidable impurities is used, and the size existing in the brazing material is 2 μm.
The above Mg ₂ Si particles are 300 particles / mm ² or more at 540 ° C during vacuum brazing and the surface film thickness of the brazing material is 750A (angstrom) or less at 530 ° C during vacuum brazing. An aluminum brazing sheet for vacuum brazing, characterized in that: