JPH05337689A - Brazing filler metal composition for brazing aluminum - Google Patents

Abstract

PURPOSE:To provide the brazing filler metal compsn. for brazing aluminum which is suppressed in oxidation reaction to aluminum brazing filler metal powder dispersed in a dispersion medium as far as possible, can maintain the excellent brazing performance possessed by a brazing filler metal mixture composed of a fluoride flux and the aluminum brazing filler metal powder in a long time and has the excellent workability for application. CONSTITUTION:This brazing filler metal compsn. for brazing aluminum is obtd. by dispersing the fluoride flux and the aluminum brazing filler metal powder into the dispersion medium. At least one or >=2 kinds of the org. solvents selected from glycols and isobutyrene are used as a part or the whole of the dispersion medium of the brazing filler metal compsn.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binder of a mixture of a fluoride-based flux and an aluminum brazing material used for brazing various aluminum materials to each other.

[0002]

2. Description of the Related Art As a method for brazing various aluminum materials to each other, the aluminum materials to be brazed to each other are degreased and washed, and these aluminum materials are temporarily assembled so that they are joined at their joints. Prior to attachment or after temporary assembly, an aqueous dispersion of a brazing filler metal mixture consisting of a mixture of fluoride flux and aluminum brazing filler metal powder is applied to the joints of the aluminum base materials, and then 100-
A method is known in which the material is dried at 150 ° C., introduced into a heating furnace, and heated to a temperature equal to or higher than the melting point of the brazing material to perform brazing.

However, when brazing is carried out by applying an aqueous dispersion of a brazing filler metal mixture to aluminum material joints in this way, the brazing performance is usually obtained by experimental tests. It is difficult to obtain the same brazing performance as the test result. That is, when a long time has passed after the brazing material composition for aluminum brazing is constructed or when the drying time before brazing is long, a thick and strong oxide film on the surface of the brazing material is used. Therefore, even if the brazing filler metal powder reaches a predetermined brazing temperature, the brazing filler metal powder only melts inside the oxide film, the oxide film is not destroyed, and some do not flow out to the joint. For this reason, the brazing filler metal becomes insufficient at the joint portion, the joint strength becomes insufficient, and in the case where it is used for manufacturing a closed container, leakage may occur at the joint portion. The problem is that increasing the amount of flux used (flux concentration) increases the ability to destroy this oxide film, which results in the above-mentioned brazing failure (insufficient bonding strength at the brazing site, leakage from the bonding site, etc.). ) Can be prevented, but the amount of flux used increases and the cost increases, and the flux residue attached to the product increases and the appearance deteriorates, and the work to remove it increases and the productivity decreases. Problems such as occur. Then, the present inventors examined the cause of such a problem, and found that the dispersion medium used when preparing the aqueous dispersion of the brazing filler metal mixture was 100% water, and the aluminum wax in this aqueous dispersion was The surface of the material powder reacts with the water of the dispersion medium over time,
It has been found that it is caused by being oxidized and forming an aluminum oxide film on the surface.

Further, when brazing is carried out by such a method, the dispersibility of the brazing filler metal mixture in water, particularly the dispersion holding power for maintaining the dispersed state, is poor, and the brazing filler metal mixture is dispersed in water at the joint portion of the aluminum material. When applying the liquid, it must be applied by spraying or dipping while always maintaining a stirring state, and there is a concentration difference in the flux and brazing filler metal in the liquid between the application and drying, There is a problem that it is difficult to uniformly apply the brazing filler metal mixture to the joint portion of the aluminum material.

[0005]

Therefore, as a result of intensive studies to solve such problems, the present inventors found that glycols and polyisobutylene were inactive on the surface of aluminum brazing powder. In addition, the addition of such glycols or polyisobutylene can suppress the oxidation reaction of water with respect to the aluminum brazing filler metal powder, and use these glycols or polyisobutylene as a part or all of the dispersion medium. It was found that the dispersion-holding power of the fluoride-based flux and the aluminum brazing material powder in the dispersion medium is improved by the above, and the present invention was completed. Therefore, the object of the present invention is to suppress the oxidation reaction to the aluminum brazing filler metal powder dispersed in the dispersion medium as much as possible, and to obtain the excellent brazing performance of the brazing filler metal mixture comprising the fluoride flux and the aluminum brazing filler metal powder. It is an object of the present invention to provide a brazing material composition for aluminum brazing which can maintain the above-mentioned properties for a long time. Another object of the present invention is to provide a brazing filler metal composition for aluminum brazing, which can maintain an excellent dispersed state for a long time and is excellent in coating workability at a joint portion of an aluminum material. It is in.

[0006]

That is, the present invention is a brazing filler metal composition for aluminum brazing obtained by dispersing a fluoride-based flux and aluminum brazing filler metal powder in a dispersion medium, and a part of the dispersion medium. Alternatively, it is a brazing material composition for aluminum brazing which uses one or more organic solvents selected from glycols and polyisobutylene as a whole.

In the present invention, as the fluoride-based flux, conventionally known ones can be used, and aluminum fluoride, alkali metal fluorides, alkaline earth metal fluorides and complex fluorides thereof (eg, , KAlF ₄ ,
K ₂ AlF ₅ · H ₂ O, K ₃ AlF ₆ , KF, Al
F ₃ , LiF, CaF ₂ , NaF, Li ₃ AlF ₆ , R
bF, CsF, BaF ₂ , AlF ₃ BaF _2, etc.) or those containing these as the main components. Also, as the aluminum brazing material powder, conventionally known ones can be used, for example, A4343, A4045, A
Examples of such materials include Al-Si alloys such as 4047, Al-Si-Zn alloys, Zn-Al alloys, and Zn-Al-Si alloys.

In the present invention, one or more organic solvents selected from glycols and polyisobutylene or these organic solvents are used as a dispersion medium for dispersing the fluoride flux and the aluminum brazing material powder. Use the aqueous solvent that contains. Although various glycols can be used here, glycols and glycol ethers are preferable. The glycol preferably has 2 to 6 carbon atoms and a boiling point of 300 ° C or lower. The glycol ether is preferably the one represented by the general formula R (OCH ₂ CH ₂ ).
_n OH (wherein R represents an alkyl group having 1 to 4 carbon atoms or a phenyl group, and n is an integer of 1 to 6) and has a boiling point of 300 ° C. or less. .. When the boiling point exceeds 300 ° C., it becomes difficult to completely remove these dispersion media when heating and drying the joint portion of the aluminum material coated with the brazing material composition, and the brazing performance deteriorates. There is a case. The viscosity of these glycols is preferably 1.0 to 20.0 cSt.
The polyisobutylene used here preferably has a viscosity of 1.0 to 10.0 centistokes (cSt) at room temperature. If the viscosity is higher than 10.0 cSt, it will be difficult to naturalize and remove it by heating, and the residue of carbonization will adversely affect brazing, and the appearance of the product after the brazing process Also causes problems. On the other hand, those having a degree of polymerization of which the viscosity is 1.0 cSt or less have a low flash point and are practically problematic at the production site where the brazing process is performed.

The organic solvent consisting of glycols and / or polyisobutylene of the present invention can be used alone as a dispersion medium for fluoride flux and aluminum brazing filler metal powder. An aqueous solvent obtained by mixing may be used as a dispersion medium. When the above organic solvent is mixed with water and used as an aqueous solvent, the amount of the organic solvent used is preferably 50.
It is preferable that the content is at least wt%, more preferably at least 90 wt%. If the amount of the organic solvent used is too small, the significance of using the organic solvent as the dispersion medium is lost.

The viscosity of the dispersion medium used in the present invention can be appropriately selected according to the desired viscosity value of the brazing material composition. In addition to these dispersion media, for example, propyl alcohol. Alcohols such as can also be used as a viscosity modifier.

When a brazing material composition is prepared using the dispersion medium of the present invention, the fluoride flux and the aluminum brazing material powder are added to this dispersion medium and the whole is uniformly mixed as in the conventional case. Good. Here, the addition amount of the fluoride-based flux and the aluminum brazing filler metal powder is also 3 to 60% by weight, preferably 10 to 20% by weight of the fluoride-based flux, as in the conventional case. Is 3 to 70% by weight, preferably 30 to 60% by weight. Further, the method for brazing an aluminum material using the brazing material composition of the present invention prepared in this way is no different from the conventional method, and the aluminum material is degreased and washed. Temporarily assemble the material so that it will be joined at the joint, and prior to this temporary assembly or after the temporary assembly, apply the brazing composition to the joint of the aluminum material by a spray method or a dipping method, and then It is dried at 100 to 150 ° C. and then introduced into a heating furnace, usually 595 to 620 ° C., preferably 600 to 6
It can be brazed by heating to a temperature of 15 ° C.

[0012]

According to the present invention, an organic solvent selected from glycols and / or polyisobutylene or an aqueous solvent containing this organic solvent is used as a dispersion medium for the brazing material composition. It is possible to prevent the formation of an oxide film on the surface of the existing aluminum brazing powder as much as possible, thereby maximizing the brazing performance of the brazing mixture composed of the fluoride flux and the aluminum brazing powder without impairing the brazing performance. Can be withdrawn. Further, since such glycols and / or polyisobutylene or an aqueous solvent containing these are used as a dispersion medium, the dispersion holding power of the brazing filler metal mixture is improved, and the coating workability at the joint portion of the aluminum material is improved. ..

[0013]

EXAMPLES The present invention will be specifically described below based on Examples and Comparative Examples. Example 1 A4047 material powder as an aluminum brazing material powder consisting of Al-Si alloy (Al-12% Si, 60 mesh or less) using 8% by weight, also, KAlF ₄ and K ₃ AlF ₆ as fluoride-based flux 32% by weight of a mixture of Alcan (trade name: Nocolok), which is a glycol ether [CH ₃ O (C ₂ H ₄ O) _n H, n
= 4-6] A brazing filler metal composition was prepared by adding and dispersing it in an aqueous solvent consisting of 30% by weight and 30% by weight of water. The viscosity of the dispersion medium of this brazing material composition was 12.0 cSt. Using this brazing filler metal composition, the capacitor A30
The joint between the 03 extruded header pipe and the A1050 extruded flat tube was brazed. Internal pressure of 1250 condensers (brazing point: 75,000 points) brazed using the brazing material composition immediately after bathing
A leak test was conducted by filling nitrogen gas so that the pressure was 5 kgf / cm ² . As a result, the probability of leakage from the brazed portion was 0.02%. In addition, internal pressure of 45 was applied to 30 capacitors (brazing point: 1800 points) brazed using the brazing material composition 3 days after the bath was built.
A leak test was conducted by filling nitrogen gas so that the pressure was kgf / cm ² . As a result, the probability of leakage from the brazed portion was 0.02%.

Comparative Example 1 A brazing filler metal composition was prepared by using 60% by weight of water as a dispersion medium without using glycol ether, and the brazing filler metal composition was prepared between the header pipe and the flat pipe of the condenser in the same manner as in Example 1 above. Brazed the joint. The viscosity of water as a dispersion medium of this brazing filler metal composition was 0.13 cSt.
A leak test was conducted on 1220 condensers (brazing points: 73, 200 points) brazed using the brazing material composition immediately after the bath was filled with nitrogen gas to an internal pressure of 45 kgf / cm ^2. It was As a result, the probability of leakage from the brazing point was only 0.08%. In addition, 30 condensers brazed using the brazing material composition 3 days after the construction bath (brazing point: 1,80
A leak test was conducted by filling nitrogen gas at 0 places) with an internal pressure of 45 kgf / cm ² . As a result, the probability of leakage from the brazing point was 17.3%.

Example 2 As the aluminum brazing material powder, 60% by weight of A4047 material powder (Al-12% Si, 60 mesh or less) made of Al-Si alloy was used, and as the fluoride type flux in Example 1. Same KAlF ₄ and K _{3 used}
5% by weight of a mixture of AlF ₆ (trade name: NOCOLOK manufactured by Alcan Co.) was used, and these were added to 35% by weight of glycol ether [C ₄ H ₉ O (C ₂ H ₄ O) ₂ H] and dispersed. A brazing material composition was prepared. The viscosity of the dispersion medium of this brazing material composition was 6.9 cSt. Using this brazing filler metal composition, A6N01 extruded joint and A300
The joint between the three extruded pipes was brazed. 1150 condensers brazed using the brazing material composition immediately after bathing (brazing joint locations: 2,300 locations)
A leakage test was conducted by filling nitrogen gas with nitrogen gas so that the internal pressure was 45 kgf / cm ² . As a result, the probability of leakage from the brazed portion was 0.3%. In addition, 3 after bathing
Leakage test was conducted on 30 condensers brazed using the aged brazing filler metal composition (brazing joint locations: 60 locations) by filling with nitrogen gas so as to have an internal pressure of 45 kgf / cm ² . As a result, the probability of leakage from the brazing point was 0.0%.

Comparative Example 2 A brazing filler metal composition was prepared using 35% by weight of water as a dispersion medium instead of glycol ether, and the joint between the joint and the pipe was brazed in the same manner as in Example 2 above. did. The viscosity of water, which is the dispersion medium of this brazing filler metal composition, is 0.1.
It was 3 cSt. Internal pressure of 45 kgf / c for 1220 condensers (brazing joint locations: 2,240 locations) brazed using the brazing material composition immediately after bathing
Leakage test was conducted by filling with nitrogen gas so as to be m ² . As a result, the probability of leakage from the brazing point is 2.4%.
Met. In addition, the internal pressure of 30 condensers brazed using the brazing material composition 3 days after the construction bath (brazing joint points: 60 points) was 45 kgf / cm ²
A leak test was carried out by filling the atmosphere with nitrogen gas. As a result, the probability of leakage from the brazing point was 51.7%.

Example 3 A4047 material powder (Al
-12% Si, 60 mesh or less) 45% by weight, the same K as that used in Example 1 as the fluoride flux.
15% by weight of a mixture of AlF ₄ and K ₃ AlF ₆ (trade name: Nocolock manufactured by Alcan Co., Ltd.) and glycol ether [CH ₃ O (C ₂ H ₄ O) _n H, n as a dispersion medium.
= 4-6], glycol ether [C ₄ H ₉ O (C ₂
H ₄ O) ₂ H] glycol (HOCH ₂ CH ₂ OH)
Alternatively, polyisobutylene having a viscosity of 6.0 cSt degree of polymerization is 4
A brazing filler metal composition was prepared by using 0 wt% of each. Four kinds of brazing filler metal compositions obtained in this way
Was used to perform a T-shaped fluidity test in the following manner.
A1050 of length 30mm x width 30mm x thickness 2.0mm
Bottom plate and length 10 mm x width 20 mm x thickness 1.0 mm A
A vertical plate made of 1050 is used, and these are fixed so as to be in contact with each other with a length of 20 mm to set a joint portion.
0.05 g of any one of the brazing filler metal compositions 1 to 3 was applied, and the brazing was carried out by holding at 610 ° C. for 2 minutes in a nitrogen atmosphere, and the size of the fillet at the joint was observed. As a result, no matter what brazing material composition was used, there was no black residue stain on the joint, and the throat thickness of the fillet was in the range of 0.6 to 0.9 mm, indicating good brazing. It was being appreciated.

[0018]

INDUSTRIAL APPLICABILITY The brazing filler metal composition for aluminum brazing according to the present invention suppresses the oxidation reaction to the aluminum brazing filler metal powder dispersed in the dispersion medium as much as possible, and the fluoride type flux and the aluminum brazing filler metal powder are contained. It is possible to maintain the excellent brazing performance of the brazing filler metal mixture consisting of the above for a long period of time, has an excellent dispersion holding power and good coating workability, and is industrially highly practical.

Claims (3)

[Claims] 1. A brazing filler metal composition for aluminum brazing, which is obtained by dispersing a fluoride-based flux and an aluminum brazing filler metal powder in a dispersion medium, and is selected from glycols and polyisobutylene as a part or the whole of the dispersion medium. A brazing material composition for aluminum brazing, which comprises using one or more organic solvents selected from the above. 2. A binder for an aluminum brazing filler metal mixture according to claim 1, wherein the glycols are glycols or glycol ethers. 3. The binder for an aluminum brazing filler metal mixture according to claim 1, wherein the boiling point of the organic solvent is 300 ° C. or lower.