JPH05228686A - Aluminum alloy brazing filler metal having excellent sodium corrosion resistance - Google Patents

Abstract

PURPOSE:To provide the aluminum alloy brazing filler metal having excellent sodium corrosion resistance. CONSTITUTION:The components of the aluminum alloy brazing filler metal consist of at least one kind of aluminum and magnesium or copper and unavoidable impurities and does not contain silicon. The content of the magnesium is preferably 0.5 to 18wt.% and the content of the copper preferably 5 to 33wt.%. This brazing filler metal is used for joining of, for example, metal-metal joined bodies, metal-ceramic joined bodies or ceramic-ceramic joined bodies, the joint boundaries of which are exposed to a molten sodium environment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy brazing material having excellent sodium corrosion resistance, which is used for joining metal-metal, metal-ceramic or ceramic-ceramic in contact with molten sodium.

[0002]

2. Description of the Related Art Ceramics are excellent in corrosion resistance, electrical insulation and mechanical properties at high temperatures, and are utilized as parts of chemical industry equipment and parts for electric industry by taking advantage of these characteristics. However, since ceramics are generally hard and brittle, they are inferior in moldability as compared with metal materials. Further, since the toughness is poor, the resistance to impact force is weak. For this reason, it is difficult to form the above component with only a ceramic material, and it is often used in the form of a joined body of a metal material and ceramics.

As a method for joining ceramics and a metal used for the above-mentioned application, for example, as disclosed in Japanese Patent Publication No. 2-49267, a core plate made of pure aluminum or an aluminum alloy is formed on the joining surface of alumina and metal by Al-. There is a method in which an insert material having a three-layer structure sandwiched between skin materials of a Si-based alloy is interposed and the alumina and the metal, which are the objects to be bonded, are heated and pressed to bond them. In addition, Japanese public Sho 61
-31074 gazette contains Si: 5-13 weight%, Ca: 0.5-1.5 weight%, Mg: 0.5-2.
A brazing material for joining ceramics and aluminum, which contains 0 wt% or Li: 0.5 to 1.0 wt% and the balance is Al, is disclosed.

[0004]

[Patent Document 1] Japanese Patent Publication No. 2-492
No. 67 and Japanese Patent Publication No. 61-31074,
An aluminum alloy containing silicon as an insert material or a brazing material is disclosed. However, since this silicon has poor corrosion resistance to molten sodium, the silicon in the brazing material is easily eroded by sodium,
There is a problem that the joined parts of the joined objects are damaged.

The problem to be solved by the present invention is to provide a metal having a joint having excellent corrosion resistance to molten sodium.
An object of the present invention is to provide an aluminum alloy brazing material excellent in sodium corrosion resistance for producing a metal, a metal-ceramic or a ceramic-ceramic bonded body.

[0006]

The aluminum alloy brazing material excellent in sodium corrosion resistance according to the present invention for solving the above-mentioned problems is a metal-metal bonded body and a metal-metal bonded body in which the joint is exposed to a molten sodium environment. An aluminum alloy brazing material used for joining a ceramics joined body or a ceramics-ceramics joined body, which is characterized by comprising at least one of aluminum and magnesium or copper and inevitable impurities.

Here, the magnesium content is 0.5 to
18% by weight is preferable, and the copper content is preferably 5 to 33% by weight.

[0008]

The aluminum-based alloy is used because it has good corrosion resistance to molten sodium. Silicon is not contained because silicon has poor corrosion resistance to molten sodium, and if it is in contact with sodium for a long period of time, silicon at the bonding interface will be corroded by sodium.

[0009] Magnesium is contained in Al-Mg
This is because the base alloy has a lower melting point than the Al-based alloy and has good operability as a brazing material. The magnesium content is
0.5-18 wt% is preferable, 0.5-10 wt% is more preferable, and 0.5-5 wt% is the most preferable. This is because if the magnesium content is less than 0.5% by weight, the melting point becomes too high and the metal to be bonded may be melted when the material to be bonded is pure aluminum or an aluminum alloy. On the other hand, if the magnesium content exceeds 18% by weight, the solidus temperature becomes too low and the heat resistance of the joint is deteriorated, which is not preferable.

The reason why copper is contained is to make the melting point low as in the case of containing magnesium and to improve the operability of joining the brazing material. The copper content is preferably 5 to 33% by weight, more preferably 5 to 20% by weight. If the content of copper is less than 5% by weight, the melting point becomes too high, and the metal to be welded may melt when the body to be welded is pure aluminum or an aluminum alloy. When the content of copper exceeds 33% by weight, the brazing material becomes brittle,
It is not preferable because it becomes difficult to process it into a plate.

The joint portion of the joint body using the aluminum alloy brazing material has excellent corrosion resistance to molten sodium. Alumina is preferable as the ceramic constituting the joined body, and an aluminum alloy or pure aluminum is preferably used as the metal.

[0012]

EXAMPLES Examples of the present invention will be described below. Experimental Example 1 Experimental Example 1 is an example in which various aluminum alloys were subjected to a dipping test in molten sodium.

The test conditions are various aluminum alloys,
Specifically, Al-20Cu, Al-10Mg, Al-
10Cu-2Mg, Al, Al-20Ge, Al-10
Each alloy of Si and Al-10Si-2Mg was kept in molten sodium at 400 ° C. for 500 hours. The shape of the test piece was a disk shape, and the outer diameter was 10 mm and the length was 1.1 mm.

In the experiment, the weight change and thickness change of the test piece before and after the test, the structure change due to the erosion of molten sodium and the corrosion resistance to molten sodium were tested. The results are shown in Table 1.

[0015]

[Table 1] In Table 1 above, “◯” indicates that the corrosion resistance to molten sodium is good, and “x” indicates that the corrosion resistance to molten sodium is poor. As a result of Table 1, it was found that the Al-20Cu alloy, Al-10Mg alloy or Al-10Cu-2Mg alloy shown in Examples 1 to 3 had good corrosion resistance to molten sodium. Since pure Al shown in Comparative Example 1 has a higher melting point than any aluminum-based alloy, operability as a brazing material is inferior to other aluminum alloys. The Al-20Ge alloy shown in Comparative Example 2 was significantly corroded by molten sodium. This is mainly due to the elution of the grain boundary phase.
Regarding the Al-10Si alloy shown in Comparative Example 3, erosion of silicon particles was remarkable. Al-10S shown in Comparative Example 4
Regarding the i-2Mg alloy, the erosion of silicon particles and silicon compound particles was remarkable.

Experimental Example 2 In Experimental Example 2, various aluminum alloys were immersed in molten sodium and the cross-sectional structure after the test was observed with an optical microscope. The test conditions were observation of the cross-sectional structure before and after immersion in molten sodium at 400 ° C. for 500 hours.
The shape of the test piece was a disk shape, and the outer diameter was 10 mm and the length was 1.1 mm. The cross section of the test piece was observed with an optical microscope. Photos of the results are shown in FIGS. Figure 1
In FIG. 3, (A) shows the cross-sectional structure before the immersion test,
(B) shows the cross-sectional structure after the immersion test.

The aluminum alloy of Example 11 shown in FIG. 1 is an Al-9 wt% Mg alloy, Example 12 shown in FIG. 2 is an Al-21 wt% Cu alloy, and Comparative Example 11 shown in FIG.
1-10 wt% Si alloy. As a result of the structure observation, in Example 11 and Example 12, no erosion to molten sodium was observed before and after the test. In contrast,
In Comparative Example 11 shown in FIG. 3, it is well understood that the silicon particles on the surface are eroded.

As a result, it was found that in Examples 11 and 12, the surface was not corroded even under the environment in which molten sodium was contacted, and excellent corrosion resistance was exhibited. This proves that when this material is used as a brazing material in the joint part of a metal-metal, metal-ceramics or ceramics-ceramics joint, it has good corrosion resistance to molten sodium.

[0019]

As described above, according to the aluminum alloy brazing material excellent in sodium corrosion resistance of the present invention,
Metal-metal, metal-ceramics or ceramics-
When it is used as a brazing material used for joining ceramics joined bodies, there is an effect that the joined portion has good corrosion resistance to molten sodium.

[Brief description of drawings]

FIG. 1 Al-9 wt% Mg shown in Example 11 of the present invention
The cross-sectional structure when the alloy is immersed in molten sodium is shown. (A) is a photograph before the immersion and (B) is a photograph after the immersion.

FIG. 2 Al-21 wt% C shown in Example 12 of the present invention
The cross-sectional structure when u alloy is immersed in molten sodium is shown, (A) is a photograph before immersion, and (B) is a photograph after immersion.

FIG. 3 shows Al-10 wt% S shown in Comparative Example 11 of the present invention.
The cross-sectional structure when the i alloy is immersed in molten sodium is shown. (A) is a photograph before the immersion and (B) is a photograph after the immersion.

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[Procedure amendment]

[Submission date] December 11, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 A1-9 wt% Mg shown in Example 11 of the present invention
Crystal structure of cross-sectional structure when alloy is immersed in molten sodium
Showing the structure , (A) is a photograph before immersion, (B)
Is a photograph after immersion.

FIG. 2 A1-21 wt% C shown in Example 12 of the present invention
Crystal of cross-sectional structure when u alloy is immersed in molten sodium
The structure is shown, (A) is a photograph before immersion,
(B) is a photograph after immersion.

FIG. 3 shows A1-10 wt% S shown in Comparative Example 11 of the present invention.
Crystal of cross-sectional structure when i alloy is immersed in molten sodium
The structure is shown, (A) is a photograph before immersion,
(B) is a photograph after immersion.

Claims (3)

[Claims] 1. An aluminum alloy brazing material used for joining a metal-metal joined body, a metal-ceramic joined body, or a ceramic-ceramic joined body whose joint is exposed to a molten sodium environment, wherein aluminum and magnesium or An aluminum alloy brazing material excellent in sodium corrosion resistance, characterized by comprising at least one kind of copper and inevitable impurities. 2. The aluminum alloy brazing material excellent in sodium corrosion resistance according to claim 1, wherein the magnesium content is 0.5 to 18% by weight. 3. The aluminum alloy brazing material excellent in sodium corrosion resistance according to claim 1, wherein the content of copper is 5 to 33% by weight.