JP2504684B2 - Flux-containing aluminum alloy brazing material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flux-containing aluminum alloy brazing material used for flux brazing aluminum or its alloy material.

[0002]

2. Description of the Related Art Conventionally, when brazing aluminum or its alloy material, the brazing material is supplied to the joint portion and the flux suspension is applied to the joint portion and heated in this state. Alternatively, it has been carried out by heating the gas while making the flux into a gas and supplying it into the atmosphere of the brazing furnace. However, in such flux brazing, the brazing material and the flux must be separately supplied to the joint, so the brazing work is troublesome, and it is difficult to make the amount of flux uniform. There was a problem that excessive amount of flux contaminates brazing products and brazing furnace.

Therefore, in order to solve these problems, various aluminum alloy brazing materials containing a flux in advance have been developed by the present applicant (for example, the brazing material described in Japanese Patent Application No. 3-346994). ). According to this flux-containing aluminum alloy brazing filler metal, it is possible to supply the brazing filler metal and the flux to the joint portion at the same time. Therefore, it is possible to save the trouble of separately supplying the flux brazing filler metal to the joint portion, and to supply a constant and appropriate amount of flux. I was able to do it.

However, when this flux-containing brazing material is used, the joint part after brazing may turn black,
Subsequent research has revealed that there is a new problem of degrading the appearance quality of brazed products.

In order to solve the above problems, the present invention is a flux-containing aluminum alloy brazing material which not only simplifies the brazing operation but also maintains the excellent appearance quality of the brazed product. Is to provide.

[0006]

As a result of repeated studies, the inventor has found that the above-described black discoloration of the joint is closely related to the amount of water contained in the starting material of the brazing material.
That is, when the amount of water contained in the brazing filler metal component powder and the flux component powder as starting materials is large, the generation of oxides is promoted in the process of pressurizing these mixed powders to form the flux containing brazing filler metal. It has been found that the oxide is considered to cause black discoloration of the joint due to reheating during brazing.

Therefore, the present invention is intended to suppress the water content in the brazing filler metal component powder and the flux component as the starting materials as much as possible. Specifically, it is composed of a pressure-molded body of a mixed powder of a brazing filler metal component powder and a flux component powder, and the brazing filler metal component powder and the flux component powder each have a water content of 1.0 wt% or less. When used, the content of Si in the brazing filler metal component is 3 to 15 wt%, and the brazing filler metal component and the flux component are mixed in a weight ratio of 99.9: 0.1 to 70:30, In addition, the density is 90% or more of the theoretical value. When the amount of water contained in the brazing material component powder and the flux component powder exceeds 1.0 wt%, it is presumed that the formation of oxides is promoted, resulting in black discoloration of the joint after brazing. Preferably, the water content in the brazing filler metal component is regulated to 0.5 wt% or less, and the water content in the flux component is regulated to 0.5 wt% or less. Also,
The water content in the mixed powder is also preferably 0.5 wt% or less, but in this case, both the brazing filler metal component and the flux component may not necessarily be 0.5 wt% or less, and the water content of the entire mixed powder may be reduced. Is 0.5 wt% or less.

In addition to Al and Si which are the main components, the brazing filler metal component may contain a metal and unavoidable impurities which are optionally added to improve the function of the brazing filler metal. As the brazing filler metal component powder which is a starting material, it is not always necessary to use a mixture of Al powder, Si powder and optionally added metal powder, and Al-Si alloy powder may be used, and these are used in combination. You may. Si content in this brazing filler metal component is less than 3 wt% or 15
If it exceeds wt%, the liquidus of the brazing material produced becomes high and brazing becomes difficult. Therefore, the Si content needs to be 3 to 15 wt% in the brazing filler metal component. Moreover, the range of especially preferable Si content is 6 to 12 wt.
%. When a plurality of materials are used together as the brazing filler metal powder, the water content of the whole brazing filler metal component is 1.0
The content of water in each material is 1.
It does not matter if it exceeds 0 wt%.

As the above-mentioned flux, a fluoride-based or chloride-based flux can be used and is not particularly limited, but a fluoride-based flux is preferable because it is non-corrosive. As the fluoride-based flux, for example, 45.8% KF-5
A complex mixture which is substantially complexed with a eutectic composition of 4.2% AlF ₃ or a composition range close thereto, KAlF
A complex of ₄ , K ₂ AlF ₅ and K ₃ AlF ₆ may be used.

The blending ratio of the brazing material component and the flux component in the alloy must be specified in the range of 99.9: 0.1 to 70:30 by weight. Flux component is 9
If it is less than 9.9: 0.1, a sufficient flux effect is not exhibited and brazing becomes difficult. On the other hand, if the amount of flux exceeds 70:30, the brazing material powder and the flux material powder are mixed. This is because it becomes difficult to solidify and it becomes difficult to manufacture the brazing material itself. The weight ratio of the brazing material powder and the flux powder is preferably 99.9: 0.1 to 85:15, and particularly preferably 98: 2 to 90:10.

The flux-containing aluminum alloy brazing material of the present invention is obtained by solidifying the above-mentioned mixed powder into an alloy body through a process such as compacting. Since air remains, the density of the flux-containing aluminum alloy brazing material is generally smaller than the theoretical value calculated from the density of each component. Therefore, in the present invention, the density of the flux-containing aluminum alloy brazing material needs to be 90% or more of the theoretical density. If it is less than 90%, the mixed powder is solidified, but there is a risk that the pores will be connected to the inside of the flux-containing aluminum alloy brazing material, making it brittle, and forming into a shape suitable for the joining member to be brazed. Because it becomes difficult. Particularly preferable flux-containing aluminum alloy brazing filler metal has a theoretical density of 95
% Or more. In addition, the brazing material powder and the flux constituent powder are preferably finely pulverized in order to uniformly mix them and densify the brazing material structure to be produced. For example, Al powder has an average particle diameter of 44 μm or less, Si powder has an average particle size of 5 μm or less, and flux powder has an average particle size of 3
It is preferably 0 μm or less.

The method for solidifying the mixed powder into a pressure-molded body is not particularly limited, but an example thereof is the method described in Japanese Patent Application No. 3-346994 mentioned above.

In this method, first, an aluminum alloy brazing filler metal component and Al powder as a flux component,
The starting materials such as Si powder, Al-Si alloy powder, and KF-AlF ₃ eutectic powder are adjusted in particle size to achieve uniform mixing thereof, and these are mixed and stirred well at room temperature at a predetermined ratio.
Then, this mixed powder is filled in a container made of a cylindrical can body, etc., and after hot degassing the inside of the container under vacuum at 1 mmHg or less, it is heated and pressed by a hot press etc., and then the can body is removed by cutting. A pressed powder compact is extruded into a desired shape such as a plate to obtain a flux-containing aluminum alloy brazing material. Here, for example, an Al can having a diameter of 3 inches and a length of 200 mm is filled with a mixed powder of Al powder having an average particle diameter of 44 μm, Si powder having an average particle diameter of 5 μm, and flux powder having an average particle diameter of 30 μm in the atmosphere, and 500 Vacuum degassing to 1 mmHg or less in a furnace at ℃, and hot pressing at 480 ° C and a load of 400 tons to form a powder compact with a height of 110 mm. If the following processing is performed, a flux-containing aluminum alloy brazing material can be obtained.

In the above method, the can body is further formed with substantially the same composition as the mixed powder or the brazing filler metal component powder excluding the flux, and the green compact is substantially integrated with the can body by heating and compacting. The aluminum alloy brazing material containing flux can be formed by coextrusion molding of various can bodies.

[0015]

The flux-containing aluminum alloy brazing material of the present invention comprises a pressure-molded body of a mixed powder of a brazing material powder and a flux material powder, and contains 3 to 15 wt% in the brazing material.
Of Si and the weight ratio of the brazing filler metal component powder and the flux component powder is 99.9: 0.1 to 70:30.
Since it is blended in a ratio of 1), an alloy structure in which the brazing material component and the flux component are uniformly mixed is formed, and when the brazing material melts during brazing, an appropriate amount of the brazing material component and the flux component are present in the joint. Supplied at the same time. In addition, since the moisture content of the brazing filler metal component powder and the flux component powder, which are the starting materials, is regulated to 1.0 wt% or less, the flux-containing aluminum alloy brazing filler metal also contains few oxides, No recoloration of the joint due to oxides occurs even after reheating.

[0016]

EXAMPLE A specific example of the flux-containing aluminum alloy brazing material according to the present invention will be described with reference to the drawings.

In the present embodiment, the brazing filler metal component powder has an average particle diameter of 44 μm and a water content of 0.5 wt%, 0.8.
wt%, 2 wt% of 3 kinds of Al powder and average particle size 1μ
Two kinds of Si powders with water content of 0.3 wt% and 2 wt% are used, and the average particle diameter is 15μ as the flux component powder.
m of water content of 0.8 wt% and 5 wt% of 45.
A eutectic powder of 8% KF-54.2% AlF ₃ was used.

First, these material powders are weighed at the ratios shown in Table 1, mixed and stirred at room temperature, and the respective materials are uniformly mixed at the composition ratio of the desired flux-containing aluminum alloy brazing material. Was prepared. On the other hand, a cylindrical container (1) having an outer diameter of 3 inches and a length of 200 mm as shown in FIG. 1 was prepared from a plate material made of an Al—Si alloy having the same composition as each brazing filler metal component.

Next, as shown in FIG. 2, after the container (1) is filled with the mixed powder (2), the container (1) is placed in a furnace at 500 ° C. and the inside of the furnace is 1 mmHg. The following vacuum was applied and degassed. Further, by hot pressing at a maximum pressure of 400 tons using a hot press at 480 ° C., the green compact of the mixed powder (2) is solidified and is substantially integrated with the container (1). Thus, a flux-containing aluminum alloy brazing material having a desired composition was obtained. The height of the green compact solidified by degassing and pressing was 110 mm.

Next, the flux-containing aluminum alloy brazing material was extruded into a flat plate having a thickness of 3 mm and a width of 30 mm at a temperature of 500 ° C. without removing the container (1) by a hot extruder.

These aluminum alloy brazing materials containing flux in the form of flat plate were extruded, densityd, brazed,
Each item of discoloration was evaluated by the following methods.

(Extrusion Moldability) The condition when extruded into a flat plate was observed.

X: Cracking occurred during extrusion.

(Density) Those having good extrusion moldability were evaluated as a percentage of the theoretical density calculated from each material.

(Brazing property) A product having good extrusion moldability was cut into a length of 10 mm, a width of 10 mm and a thickness of 3 mm, and was made of an A3003 alloy and had a length of 100 mm and a width of 100 mm.
× Placed on a flat plate with a thickness of 2 mm, 600 ° C in N ₂ atmosphere ×
After heating for 10 minutes, the spread state of the brazing material was observed.

B: The brazing material was sufficiently wet and spread, and the brazing property was good.

X: Wetting and spreading of the brazing material was insufficient and brazing property was poor.

(Discoloration) The discolored state of the joint portion of the test piece after brazing was observed.

◯: No discoloration was observed at all.

X: The color changed to black.

[0031]

[Table 1] As is clear from the results in Table 1, all of the brazing materials of Examples 1 to 7 were excellent in brazing property and did not discolor. In addition, in Example 7, the water content of the Si powder was 1.
Although it exceeds 0 wt%, the Al powder, which occupies 90 wt% of the brazing filler metal component, has a water content of 0.5 wt% and the total brazing filler metal component has a water content of 1.0 wt% or less, causing discoloration. Probably not. On the other hand, Al with high water content
In Comparative Examples 1 to 3 using powder, Si powder and flux powder, black discoloration occurred. Further, Comparative Example 4 containing no flux component and Comparative Examples 6 and 7 having an excessively low or excessive Si content have poor brazing properties, and even Comparative Example 5 having an excessive amount of flux has difficulty in extrusion molding. It was

[0032]

The flux-containing aluminum alloy brazing filler metal of the present invention comprises a pressure-molded body of a mixed powder of the brazing filler metal component powder and the flux component powder.
In addition to containing 5 wt% of Si, the brazing filler metal component powder and the flux component powder have a weight ratio of 99.9: 0.1-7.
Since it is mixed at a ratio of 0:30, it forms an alloy structure in which the brazing material component and the flux component are uniformly mixed,
When the brazing material melts during brazing, an appropriate amount of brazing material component and flux component are simultaneously supplied to the joint. Therefore, it is not necessary to separately supply the flux at the time of brazing, and the labor of the work can be simplified and good brazing can be achieved. In addition, the content of water in the brazing filler metal component powder and the flux component powder, which are the starting materials, is 1.0 wt% each.
Since it is regulated as follows, the amount of oxide contained in the flux-containing aluminum alloy brazing material is small, and discoloration due to oxide does not occur at the joint even when reheating during brazing, so the brazed product has excellent appearance quality. It becomes a thing.

[Brief description of drawings]

FIG. 1 is a perspective view of a container used in an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of a container filled with a mixed powder in an example of the present invention.

[Explanation of symbols]

 1 ... container 2 ... mixed powder

Claims (1)

(57) [Claims] 1. A pressure molding of a mixed powder of a brazing material powder and a flux material powder, wherein the brazing material powder and the flux material powder are:
A water content of 1.0 wt% or less is used, and the Si content in the brazing filler metal component is 3 to 3%.
15 wt%, and the brazing material component and the flux component are mixed in a weight ratio of 99.9: 0.1 to 70:30, and the density is 90% or more of the theoretical value. Flux-containing aluminum alloy brazing material.