JPH06304784A - Flux-containing Al alloy brazing material manufacturing method - Google Patents

Abstract

(57) [Summary] [Objective] An object of the present invention is to provide a method for producing a flux-containing Al alloy brazing material capable of producing a stable quality flux-containing Al alloy brazing material at low cost. According to the method for producing a flux-containing Al alloy brazing filler metal of the present invention, a mixed powder of a brazing filler metal component powder and a flux component powder is cold pressed to form a green compact. Less than 500ppm, water concentration 500
In a non-oxidizing atmosphere controlled to be ppm or less, the mixed powder and water contained in the green compact are heated at a temperature at which they do not react with each other to dehydrate, and then heated to a predetermined temperature to be heated. Characterize.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a flux-containing Al alloy brazing material used for 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 flux suspension is applied to the joint portion and heated in this state, or the flux is made into a gas state. It was carried out by heating while supplying it to 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. To solve these problems, various Al brazing materials containing flux have been developed by the present applicant (for example, the brazing material described in Japanese Patent Application No. 3-346994).

The flux-containing Al brazing material is manufactured, for example, as follows.

First, Al powder, Si powder, Al-Si alloy powder, KF- which are brazing filler metal components and flux components.
The particle size of AlF ₃ eutectic powder and the like is adjusted and well dried, and these are well mixed and stirred at a predetermined ratio at room temperature. Next, this mixed powder is filled in a container composed of a cylindrical can body and the like, and after hot degassing the inside of the container under vacuum at 1 mmHg or less by hot pressing with a press or the like, the powder particles are fused and the compressed powder is produced. And the container are crimped and integrated. Then, the container portion of the powder compact is cut and removed, and then extruded into a desired shape such as a plate to obtain a flux-containing Al alloy brazing material.

Further, in the above-mentioned manufacturing method, in order to omit the step of removing the container, the container is formed into a composition having the same composition as the mixed powder to which the brazing material component or the flux component is added, and the powder is pressed and then the various containers are mixed. Al extruded and containing flux
It is also used as an alloy brazing material (Japanese Patent Application No. 4-18).
7949).

However, as described above, a large amount of equipment is required for hot degassing by vacuum depressurization to form a heated green compact, so that the manufacturing cost of the flux-containing Al alloy brazing material is high. Therefore, in order to reduce the manufacturing cost, a simple manufacturing method of manufacturing a green compact by cold and then heating the green compact in the atmosphere to prepare a heated green compact was tried.

[0007]

However, although the above-described simple manufacturing method is satisfactory in terms of reducing the manufacturing cost, when brazing is performed using the manufactured flux-containing Al alloy brazing material, the wettability is improved. There was a problem that a bad brazing could occur and a stable brazing material quality could not be obtained.

The present invention aims to solve the above problems and provides a method for producing a flux-containing Al alloy brazing material capable of producing a flux-containing Al alloy brazing material of stable quality at low cost. Is.

[0009]

As a result of various studies on stability of brazing material quality and manufacturing method, the inventors have found that good brazing property is deeply related to atmospheric humidity when heating a green compact. Therefore, the inventors have attempted to achieve the above object by controlling the heating atmosphere of the green compact. That is, the method for producing the flux-containing Al alloy brazing filler metal of the present invention is to press the mixed powder of the brazing filler metal component powder and the flux component powder in a cold state to form a green compact, and to reduce the oxygen concentration of the green compact. 500ppm or less, water concentration 500p
In a non-oxidizing atmosphere controlled to pm or less, heating is performed at a temperature at which the mixed powder does not react with water contained in the green compact to dehydrate, and then the temperature is further raised to a predetermined temperature for heating. It is a feature.

The brazing filler metal component in the present invention is not particularly limited as long as it can be used for brazing aluminum or its alloy material, and is made of Al and Si, and other components containing these as the main components. The thing containing Zn, Cu, etc. can be illustrated. As a typical brazing filler metal composition, one containing Al as a main component and 3 to 15 wt% of Si can be mentioned. Note that Al, Si, etc. do not necessarily have to be used alone as these brazing filler metal component powders, and alloy powders having a predetermined composition may be used, or these may be used in combination.

Further, the kind of the flux is not particularly limited, and a fluoride-based or chloride-based flux can be used, but the fluoride-based flux is preferable from the viewpoint of non-corrosiveness. Examples of the fluoride-based flux include 45.
8% KF-54.2% AlF ₃ eutectic composition or a complex mixture substantially complexed with a composition range close to this, KAlF ₄ , K ₂ AlF ₅ , K ₃ AlF _6, etc. Should be used. Further, as the chloride-based flux, one having a low hygroscopicity is preferable in order to suppress the corrosion of the brazing part, and specifically, BaCl ₂ , NaCl,
A material containing KCl or ZnCl ₂ as a main component is preferable, and BaC
l ₂ -NaCl-KCl ternary eutectic composition of what is its representative example.

In the present invention, the flux-containing Al alloy brazing filler metal composition is determined by mixing the brazing filler metal component powder and the flux component powder described above in a predetermined ratio.
In the mixed powder used as the raw material of the flux-containing Al alloy brazing material, the mixing ratio of the flux is 99.9: 0.1 to 7 by weight ratio of the brazing material component powder and the flux component powder.
It is preferable to mix them so as to be 0:30. When the amount of flux is less than 99.9: 0.1 by weight, sufficient flux action cannot be exhibited and brazing becomes difficult. On the other hand, when the amount of flux exceeds 70:30, flux and Al, Secondary processing such as extrusion by mixing with Si or the like becomes difficult, and it becomes difficult to manufacture the flux-containing Al alloy brazing material itself. The preferable mixing ratio of the brazing material component and the flux component is 99.9 by weight.
0.1 to 85:15, particularly preferably 9 by weight.
It is 8: 2 to 90:10.

In the present invention, first, the above-mentioned mixed powder is cold pressed to prepare a green compact. The density of the green compact at this time is generally smaller than the theoretical value calculated from the respective densities of the respective material powders because air remains inside the green powder during the green compact. However, in order to ensure the handleability of the green compact and to facilitate the secondary processing performed after heating, the green density needs to be as high as possible, and at least 50% or more of the theoretical density is preferable. . Further, in order to increase the density of the green compact, it is preferable to use finely pulverized material powders. For example, Al powder has an average particle diameter of 44 μm or less, Si
The powder preferably has an average particle size of 5 μm or less, and the flux powder preferably has an average particle size of 30 μm or less. It should be noted that such particle size adjustment is also preferable from the viewpoint of uniformly mixing the powders of the respective materials and homogenizing the brazing alloy structure.

The heat treatment of the present invention must be carried out in a non-oxidizing atmosphere in which the oxygen concentration and the water concentration are controlled to 500 ppm or less. An example of the non-oxidizing atmosphere is an atmosphere of an inert gas such as He gas, Ar gas, N ₂ gas. The oxygen concentration and the water concentration in the atmosphere are controlled to 500 ppm or less, because when either one of them exceeds 500 ppm, the oxidation of the mixed powder forming the green compact is promoted and the produced flux-containing Al alloy is produced. This is because the brazing property of the brazing material decreases. Therefore, an inert gas with a high water content or dry air that merely controls the water content is not suitable. In particular,
It is preferable to control the oxygen concentration and the water concentration to 100 ppm or less.

The heat treatment in such a non-oxidizing atmosphere is performed in two steps.

In the first-stage heat treatment, the main purpose is to dehydrate the green compact, and the powder is held and heated at a predetermined temperature at which the mixed powder does not react with the water contained in the green compact. If the heat treatment temperature is too high, the mixed powder is oxidized by the time the moisture contained in the green compact is discharged, or the powder particles are fused to confine the moisture in the green compact. On the other hand, if the heat treatment temperature is too low, water is not discharged, or even if water is discharged, the discharging speed is extremely slow, which is not practical. Taking this into consideration, the heat treatment temperature is preferably about 150 to 500 ° C. Further, the heat treatment needs to be performed until the moisture in the green compact is sufficiently discharged to the outside of the body. Specifically, the moisture concentration in the atmosphere is 50%.
It is preferable to carry out the process until it becomes about 0 ppm or less. This is because when the moisture concentration in the atmosphere exceeds 500 ppm, the moisture is not sufficiently discharged, and the moisture remaining in the green compact may accelerate the oxidation of the mixed powder to deteriorate the brazing performance. Particularly preferably, the moisture concentration in the atmosphere is 100.
It is better to heat up to below ppm. Although the specific heat treatment time varies depending on the heating temperature, the size and density of the green compact, and the like, for example, a diameter of 76.2 mm × height 100
In the case of a cylindrical green compact of mm, the temperature is 300 ° C. and the time is about 2 to 3 hours.

The second step of heating, which is carried out in a non-oxidizing atmosphere after the first step, is for the purpose of fusing the powder particles constituting the green compact to form a strong alloy brazing alloy structure. Perform at a higher temperature than the first step. Heating temperature is 500-54
The temperature is about 0 ° C., and there is no problem even if the temperature is rapidly raised from the heating temperature in the first stage to this temperature. Further, the processing time is not particularly limited, and if the size is the same as that of the cylindrical green compact, it is 0.
About 5 to 2 hours is sufficient.

The flux-containing Al alloy brazing material produced through the heat treatment as described above is formed into a predetermined shape by secondary processing such as extrusion, forging and rolling, if necessary, and is provided for brazing.

[0019]

The powder compact formed by cold-pressing the mixed powder of the brazing filler metal component powder and the flux component powder is mixed with the powder mixture in a non-oxidizing atmosphere in which the oxygen concentration and the water concentration are controlled to 500 ppm or less. The moisture is sufficiently discharged to the outside of the green compact by heating and holding at a temperature at which the water contained in the green compact does not react, that is, at a relatively low temperature. Then, by heating up to a predetermined temperature of a relatively high temperature in the same non-oxidizing atmosphere and heating, the powder particles constituting the green compact are fused and a strong alloy brazing alloy structure is formed. In such a heating step, since the green compact is hardly oxidized, the produced flux-containing Al alloy brazing material has excellent brazing property.

[0020]

EXAMPLE A specific example of the method for producing the flux-containing Al alloy brazing material of the present invention will be described below.

The material powder has a purity of 9 as a brazing filler metal component.
9.5% Al powder having an average particle size of 44 μm, Si powder having an average particle size of 1 μm, and an average particle size of 15 as a flux component.
A μm eutectic powder of 45.8% KF-54.2% AlF ₃ was prepared.

First, 72 wt% of Al powder was added to these material powders.
%, Si powder 8 wt% and flux powder 20 wt% were weighed and mixed and stirred at room temperature to prepare a mixed powder in which the respective materials were uniformly mixed at the desired composition ratio of the flux-containing Al alloy brazing material. . This mixed powder was cold pressed to have a density of 77% of the theoretical value, a diameter of 76.2 mm and a length of 1
A cylindrical green compact of 00 mm was prepared.

Next, this green compact was heat-treated under the conditions such as atmosphere and temperature shown in Table 1. In addition, for each brazing material of each number, after the heating temperature reaches 500 ° C, 500
Hold at 1 ° C for 1 hour.

Then, the mixture was extruded by a hot extruder at a temperature of 500 ° C. into a flat plate having a thickness of 3 mm and a width of 10 mm. In addition, extrusion molding could be performed satisfactorily with any brazing material.

The brazing properties of these flux-containing Al alloy brazing materials were evaluated by the following method.

Each plate-shaped flux-containing Al alloy brazing material was cut into a 10 mm square and placed on a flat plate made of A3003 Al alloy and having a width of 10 mm, a length of 10 mm and a thickness of 5 mm.
Heated at 600 ° C. for 1 minute in air and N ₂ atmosphere. Then, the brazing property was evaluated by observing the spread state of the brazing material.

The results of these evaluations are also shown in Table 1.

[0028]

[Table 1] As is clear from the results in Table 1, the oxygen concentration is 100 pp.
m or less, and in a N ₂ gas atmosphere in which the water concentration was controlled to 200 ppm, the water concentration in the atmosphere was 2 at a low temperature of 300 ° C.
Brazing material No. No. which was sufficiently heated for 3 hours until it became less than 00 ppm. 2 is of course in N ₂ gas atmosphere,
The brazing property was good even in the atmosphere. On the other hand, No. Even in the same atmosphere as in No. 2, the brazing filler metal N heated up to 500 ° C. at a stretch without performing the low temperature heat treatment at 300 ° C.
o. In No. 1, the dehydration of the green compact was insufficient and the brazing property was poor. Further, the brazing material was heated in a high moisture concentration N ₂ atmosphere No. Regarding Nos. 3 and 4, No. 3, which was not subjected to the low temperature heat treatment at 300 ° C. No. 3, which is of course subjected to the low-temperature heat treatment, 4 Brazing was poor. Also,
No. No. which was heat-treated in dry air whose water concentration was controlled to 200 ppm. Regarding Nos. 5 and 6, No. 5 subjected to low temperature heat treatment at 300 ° C. No. 6 of the present invention had a good brazability, but the product No. 6 of the present invention. It was not two. In addition, No. 1 which was heat-treated in the atmosphere in which neither oxygen nor water was controlled
Brazing was bad for 7 and 8.

[0029]

The method for producing a flux-containing Al alloy brazing filler metal according to the present invention comprises cold pressing a powder mixture of a brazing filler metal component powder and a flux component powder to form a green compact. Oxygen concentration less than 500ppm, water concentration 5
Heating and dehydrating by heating at a temperature at which the mixed powder does not react with the water contained in the green compact in a non-oxidizing atmosphere controlled to be 00 ppm or less, and then heating to a predetermined temperature. Therefore, the formation of the green compact and the heat treatment thereof are performed in separate steps, and no heating equipment is required when forming the green compact. Therefore, the manufacturing equipment can be simplified, and the manufacturing cost of the flux-containing Al alloy brazing material can be reduced as compared with the conventional case. Moreover, the heat treatment mainly aims at dehydration of the green compact in a non-oxidizing atmosphere at a relatively low temperature and fusion of the powder particles to form a strong brazing alloy structure. Since the heating is carried out in two steps, that is, heating at a relatively high temperature, there is almost no oxidation of the brazing material in the manufacturing process, and a flux-containing Al alloy brazing material having excellent brazability and workability can be stably manufactured.

Claims (1)

[Claims] 1. A powder compact is formed by cold pressing a mixed powder of a brazing filler metal component powder and a flux component powder, and the powder compact has an oxygen concentration of 500 ppm or less and a moisture concentration of 5 ppm.
In a non-oxidizing atmosphere controlled to 00 ppm or less, the mixed powder and water contained in the green compact are heated at a temperature at which they do not react with each other for dehydration, and then the temperature is further raised to a predetermined temperature for heating. A method for producing a flux-containing Al alloy brazing material, which is characterized.