JPH0399772A - Vapor phase brazing method for al or al alloy - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for vapor phase soldering of Al or Al alloy, and is used, for example, in the manufacture of automobile heat exchangers, to solder the brazed members thereof. This is to improve performance and reduce manufacturing costs.

[Conventional technology]

Normally, Al or Al alloy brazes are assembled by fixing the Al or AN alloy members to be joined via a brazing material whose melting point is lower than that of Al, etc.; This is done by heating to a temperature lower than the melting point of the An or Al alloy members to be joined. A7Si alloy is generally used as the brazing material, and its shape is a plate.

It is used in the form of a linear or powdered brazing material, or a laminated material (hereinafter referred to as a plating sheet) in which a core material made of Al or an Al alloy is coated with the brazing material.

As conventional brazing methods, flux brazing, which uses flux to remove the oxide film on the surface of the parts to be brazed, and vacuum brazing, which does not use flux, are commonly used.

The above-mentioned flux brazing properties include furnace brazing properties in which an assembly to be bonded is immersed in molten chloride-based flux and then heated for brazing. However, since this chloride-based flux is corrosive to An, it must be completely removed by washing after the wax (=1), making the manufacturing process very complicated.

On the other hand, according to the vacuum brazing method, in which the assembly to be welded is placed in a vacuum and heated, cleaning is not necessary as a post-process, and the surface of the parts after brazing is also good. However, there are problems such as the need for high vacuum and material limitations. Furthermore, I recently solved the above problem! 1
For brazing properties, a method of brazing in a furnace using fluoride flux has come to be widely used.

This method, as described in Japanese Patent Publication No. 58-27037, uses a mixture of IF, A/F6, which is non-hygroscopic and non-corrosive to 1, and mixed with water. It is suspended in a flux and applied to the surfaces of the assemblies to be joined to give a wax (=1), and its feature is that since it uses a non-corrosive flux, no post-treatment to remove the flux is required.

[Problem to be solved by the invention]

However, the method described in Japanese Patent Publication No. 5g-27037 mentioned above necessarily requires a coating and drying process for adhering the flux to the surface of the assembly, and furthermore, the applied flux is used to transfer the assembly to the next process. Many items fall off from the assembly during transport, and as a result, the yield of effectively used flux is low.

Additionally, since flux residue remains unevenly on the surface of the joint after brazing, the surface becomes dirty compared to conventional vacuum brazing, resulting in inferior commercial value. Chromate treatment, black paint treatment, etc. became uneven, and the effects were not fully demonstrated (there were disadvantages such as chromate treatment and black paint treatment.Furthermore, flux residue is non-conductive, so it can be used as a sacrificial material in heat exchangers, etc.). When a corrosion prevention method is adopted in which the pipe body is protected by fins, the flow of the corrosion prevention current is obstructed and a sufficient corrosion prevention effect may not be obtained.

Furthermore, when brazing Mg-containing Al alloys in a furnace using a fluoride flux (=1), the brazing properties are inferior to conventional ones, so in order to obtain industrially stable brazing properties, The content of Mg must be less than 0.6 wt% (hereinafter wt% is simply abbreviated as %).

For Al alloys containing more Mg than this, brazing becomes difficult even if the amount of flux applied is increased.

The cause of this is that Mg in the Al alloy reacts with the flux during brazing heat, and as a result, the composition of the flux changes and its effectiveness as a flux is lost.
This is because the Mg in the Al alloy diffuses into the surface layer, increasing the Mg concentration in the surface layer, and phenomena such as flux entering the surface layer of the Al alloy occur, inhibiting the flow of the solder. It is. In this way, A with a high Mg content
The fact that l-alloy cannot be used as a material for heat exchangers has been a major obstacle in terms of durability and weight reduction of heat exchangers.

[Means to solve the problem]

In view of this, as a result of various studies, the present invention has developed vapor phase brazing properties that do not require the process of directly applying flux to the assemblies to be joined.

That is, one aspect of the present invention is a method of brazing through Al or AA gold alloy brazing material, in which the members to be brazed are placed in a non-oxidizing atmosphere in which vapor of chloride or fluoride flux is present. Then, the flux vapor partial pressure P fl
u, (mmHg), oxygen partial pressure P 02 (
This method is characterized in that brazing is carried out in an atmosphere in which the partial pressure of water vapor (mmHg) and water vapor partial pressure P H2O (mmHg) satisfy all the relationships of the following formulas (1) to (2).

(2x P 02 + P H2O)≧0.6x lo
g(P+1.,,) ・−−■(2X, P 02 +
P H2O)≦2.3x lOg (pH1,x)
+ 3.0...■(2xPO□+PH2O)≦-5,
3x log (pn,,x) +14・・・・・・■
Another aspect of the present invention is that the M content is 0.3% or more and less than 2.3%.
In the method of brazing an Al alloy containing g through a brazing material, the member to be brazed is heated in a non-oxidizing atmosphere in the presence of vapor of chloride or fluoride flux. Flux vapor partial pressure P 1lnx (m
ml1g), oxygen partial pressure P O2 in the atmosphere (mmHg
) and water vapor partial pressure PH2O (PH2O (but the next
This method is characterized by brazing in an atmosphere that satisfies all of the relationships expressed by formulas (1) to (2).

(2×PO2+PH2O)≧0.6x log cp
)lux)0.4-■(2×PO2+PH,O)≦2.
3x log(Pa1.,) +3.0-■(2X
P 02 + P H2O)≦-5,3x log (
P,,,,) +14-=■ [Function] In this way, by placing the assembly as the member to be joined in a non-oxidizing atmosphere in which vapor of chloride or fluoride flux exists, This vapor adheres uniformly to the assembly in a very small amount and destroys the oxide film of Aff on its surface, promoting wetting of the wax and causing the wax to flow like a...
It has the characteristic that a uniform fillet is formed at the joint portion of the assembly.

Therefore, the flux that can be used in the present invention is A
It is a compound containing a chloride or fluoride compound that can destroy the oxide film of A, a metal complex from which the above compound can be formed after evaporation, or a single substance. Specifically, zinc chloride,
Contains vapors such as tin chloride and fluoroaluminate metal complexes, and further contains 1 AA F4+, 2 An F,
- Also includes vapors generated from mixtures such as H2O.

To generate such steam, the above mixture etc. may be placed in advance in the furnace where brazing will be carried out, and when the temperature of the furnace is raised, it may be evaporated at the same time, or this steam may be It is also possible to generate nitrogen gas outside and supply it into the furnace using nitrogen gas or the like as a carrier.

Moreover, the presence of such flux vapor in a non-oxidizing atmosphere allows the assembly to be completely covered with vapor, so that the vapor density is low (waste) and flux consumption can be reduced.

In general, flux vapor also has the effect of chemically suppressing the effects of moisture and oxygen in the atmosphere. Therefore, flux is used to destroy the surface oxide film and is also consumed to remove oxygen or water vapor from the atmosphere. However, if the atmosphere is highly oxidizing relative to the amount of flux, the flux will destroy the Al oxide film, but an oxide film will be formed again due to the action of the oxidizing atmosphere such as oxygen or water vapor, so brazing sexuality deteriorates. On the other hand, if the flux concentration is excessive, the amount of flux remaining on the product surface in addition to that consumed by the above-mentioned effects increases, and the flux that adheres to the surface impairs corrosion resistance and causes a decrease in surface quality. Therefore, in order to ensure good brazing properties, (2×PO2-1-PH2O)≦2.3Xlog(P
++, 1-) + 3.0-■ In order to maintain corrosion resistance or surface quality, (2×PO2+PH2O)≧0.6
u. ) ・・・・・・・・・■ In this case, it is necessary to satisfy the following conditions: It turned out that I was consuming too much.

Therefore, in particular, Mg must be 0.3% or more and 23% or less.
'j containing Al alloy is (■) (2X P 02 +P H2O) ≧ 06 og (P,
Corrosion resistance or surface quality can be maintained up to the following conditions.

Furthermore, flux and oxygen or water vapor exhibit chemical reactions depending on their respective concentration ratios, but when the concentration exceeds a certain level, the above reactions do not occur in time, and a large amount of flux adheres to the surface of the brazed parts, and oxygen Alternatively, water vapor increases the amount of reaction (oxidation) with the Al surface, deteriorating the wax (= J property. Therefore, (2×PO2+PH2O)≦-5,3x+og(p+1
．． ,,) +14-, ,, ■(■) must be satisfied.

Here, examples of the non-oxidizing atmosphere include nitrogen argon, -
It can be used in any atmosphere including carbon oxide. Although it is possible to practice the invention in a vacuum instead of a non-oxidizing atmosphere, the economic benefits will be reduced.

Of course, under the above conditions, (2×PO2+PH2O)≧0 It has meaning only within the range of conditions.

1 〔Example〕 Next, examples of the present invention will be described.

<Example> As shown in Fig. 1, a tube material (1) made of "II5A+050 CAI 99.5% or higher" (2) which was hot-extruded into a tube shape by a conventional method is bent into a meandering shape, and this meandering tube material (1) is An alloy sample with the basic composition of Al-1%Mn-1%Zn alloy and the addition of Mg at each concentration shown in Table 1 was used as the core, and Δ1-10%5i-1-% was added to both sides of the core. Blazing sea I with thickness 0.16mm clad with Zn alloy skin
・Sandwiching the corrugated fins (2) consisting of
-/I%Zn-1%Mg alloy connector (3)
Take the (1) ll5Al047 CA
A serpentine type capacitor was assembled by winding a wire with a wire diameter of 1.6 mm made of (11 to 13% Si).

This assembly was degreased with an organic solvent and placed on a stainless steel tray on which a predetermined amount of I and ΔρF4 was placed per cubic meter of internal volume of the brazing furnace. Then, this tray was inserted into an electric furnace maintained at 610°C and replaced with a nitrogen gas atmosphere at each oxygen partial pressure and waterfish partial pressure shown in Table 1, and the above assembly was heated to 610°C.
Brazing was performed by heating at 10° C. for 5 minutes. KA+[F
After 4 is inserted into the furnace, it melts and evaporates while being heated at a humidity temperature of J. At this time, the concentration of the gas extracted from the container is analyzed to determine the partial pressure of the flux vapor in the atmosphere. The results are shown in Table 1.

After the above-mentioned waxing, the capacitor was taken out of the furnace and the appearance of the surface was observed.The waxing condition was also investigated and the results are shown in Table 1.Then, the capacitor was chromate treated and painted black using the usual method. The adhesion properties were also listed in Table 1 as chromate property and paintability.In addition, to evaluate the corrosion resistance of the capacitor after coating, ll5II86
A CASS test based on 81 was carried out for 500 hours to check for the presence or absence of through pitting corrosion, and the results are also listed in Table 1. We also evaluated the economic efficiency of manufacturing in comparison with currently known brazing methods.

<Conventional Example> 3 For comparison, the characteristics of the capacitor assembly shown in FIG. 1 above were brazed using a conventional method were investigated. That is, after degreasing the assembly shown in Fig. 1 with an organic solvent, a 10% concentration of K
Drying was performed at 0°C for 10 minutes. Thereafter, this assembly was inserted into an electric furnace that was purged with a nitrogen gas atmosphere and maintained at 610° C., and heated at 610° C. for 5 minutes (=1 was performed).

The subsequent steps were carried out in the same manner as in the above-mentioned <Example>, and evaluation tests similar to those described above were conducted on this soldered capacitor (=J), and the results are shown in Table 1.

4. As is clear from Table 1, the surface of the capacitor after brazing according to the present invention is clean, and the brazing conditions are as follows: the fin section, which is the joint between the fin and the tube material, and the connector, which is the joint section between the connector and the tube material. Some of them were both excellent. Furthermore, the chromate paintability was also good, and the corrosion resistance was also good.

On the other hand, with conventional capacitors, the flux residue is thick and uneven on the entire surface (= one coat of flux residue is deposited on the surface).
Two unfavorable. In addition, although the fin portion was in good condition, some connectors could not be brazed. Furthermore, the chromate treatment and painting after brazing are uneven, and the corrosion resistance is particularly poor at the bent part of the pipe material (1) in Figure 1.
4), pitting corrosion occurred on 11 occasions.

Comparative method No. 6 and No. 0, which are out of formula 0, have good chromate properties and paintability, but poor corrosion resistance and surface appearance. (Formula 0) and Comparative Method No. 7, which deviates from Equation 0 (Formula Ⅰ), are found to be inferior in all items.

6 [Effects of the Invention] As described above, according to the present invention, the manufacturing process of heat exchangers for automobiles, etc., can be shortened compared to the conventional brazing (=1 method), resulting in lower manufacturing costs. Because the surface of the alloy is clean, it has good surface treatment properties in post-treatments such as chromate treatment, and its quality is improved, such as excellent corrosion resistance. This has a remarkable effect.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of a condenser which is a heat exchanger for an air conditioner, and FIG. 2 is a side view showing an enlarged joint portion of fins. 1...Tube material 2...Fin 3...Connector 4...Bending part 7

Claims (1)

[Claims] (1) In a method of brazing Al or Al alloy through a brazing material, the parts to be brazed are placed in a non-oxidizing atmosphere in which vapor of chloride-based or fluoride-based flux exists, and the flux vapor Partial pressure P_f_l_u_x(m
mHg), oxygen partial pressure PO_2 (mmHg) and water vapor partial pressure PH_2O (mmHg) in the atmosphere are as follows [1
A vapor phase brazing method for Al or Al alloy, characterized in that brazing is performed in an atmosphere that satisfies all of the relationships of formulas 1 to 3. (2×PO_2+PH_2O)≧0.6×log(P_
f_l_u_x)・・・・・・・・・[1](2×PO
_2+PH_2O)≦2.3×log(P_f_l_u
＿x)+3.0...[2](2×PO_2+PH_2
O)≦-5.3×log(P_f_l_u_x)+14
...... [3] (2) 0.3wt% or more 2.3wt
In a method of brazing Al alloys containing less than % Mg through a brazing material, the parts to be brazed are placed in a non-oxidizing atmosphere in the presence of vapor of chloride or fluoride flux, and the flux Steam partial pressure P_f_l_u_
x (mmHg), oxygen partial pressure in the atmosphere PO_2 (mmH
g) and vapor phase brazing of Al or Al alloy, characterized in that brazing is carried out in an atmosphere where the water vapor partial pressure PH_2O (mmHg) satisfies all the relationships of the following formulas [4] to [6]: Attachment method. (2×PO_2+PH_2O)≧0.6×log(P_
f_l_u_x)-0.4...[4](2×PO_2
+PH_2O)≦2.3×log(P_f_l_u_x
)+3.0...[5] (2×PO_2+PH_2O)
≦-5.3×log(P_f_l_u_x)+14...
...[6]