JPH08169778A - Brazing filler alloy for joining alumina ceramics to aluminum alloy and joined body - Google Patents

Abstract

PURPOSE: To metallically join alumina ceramics to an Al alloy without carrying out any pretreatment and to attain joining with high strength, high stability, high heat resistance and high heat conductivity. CONSTITUTION: This brazing filler alloy consists of 5-45wt.% Ge, 5-15wt.% Si, 2-10wt.% Mg and the balance Al. This joined body is obtd. using this alloy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brazing alloy used for brazing alumina ceramics and aluminum alloys and a joined body of alumina ceramics-aluminum alloy.

[0002]

2. Description of the Related Art Conventionally, the following closely related techniques are known as a technique for joining the alumina-based ceramic and the aluminum alloy, which is the object of the present invention.

First, as a technique for joining an alumina-based ceramic and a metal, as shown below, (1) brazing with an active metal braze and (2) a metallizing method are known.

In the brazing with the active metal brazing (1), the ceramic and the metal are brazed with a brazing metal (active metal brazing) containing a metal (active metal) such as Ti and Zr which chemically reacts with the ceramic. Is the way. The basis of the active metal braze used in this method is Ag-Cu braze, the brazing temperature is 800-1000 ° C.

In the metallizing method (2), a surface layer (metallizing layer) containing a refractory metal such as Mo or W is provided on the surfaces of the ceramics to be joined, and the surface layer is plated with a metal such as Ni. This is a method of brazing the plated layer and the mating metal member.

On the other hand, the only effective method for joining the aluminum alloy to other materials is (3) a method of joining using an adhesive.

[0007]

However, as described below, none of the above-mentioned conventional methods is suitable for joining the alumina-based ceramic and the aluminum alloy.

The method (1) cannot be applied to the joining of aluminum alloy and ceramics. This is because the treatment temperature of this method is higher than the melting point of aluminum alloy (generally 600 ° C. or lower), and the aluminum alloy members to be joined are melted.

In the method (2), brazing can be performed by using a brazing material for aluminum alloy with the metallized layer and the plated layer provided on the ceramic surface. But,
Productivity is poor because a two-step pretreatment of metallizing treatment and plating treatment is required before brazing.

In the method using an adhesive as in (3),
High strength, high stability, high heat resistance, and high thermal conductivity cannot be obtained.

The present invention has been made in order to solve the above problems, and alumina-based ceramics and aluminum alloys can be metallically joined without any pretreatment, and high strength, high stability, The purpose is to obtain a joint having high heat resistance and high thermal conductivity.

[0012]

A brazing alloy for joining according to the present invention is a brazing alloy used for joining an alumina-based ceramic and an aluminum alloy, and contains 5 to 45 wt% of G.
e, 5 to 15 wt% of Si, 2 to 10 wt% of Mg, and the balance Al.

The joined body of the present invention is a joined body in which an alumina-based ceramic and an aluminum alloy are joined by a brazing alloy, and the brazing alloy is 5 to 45 wt% Ge, 5 to 15 wt% Si, 2-10 wt% Mg,
The balance is made of Al.

In the present invention, the alumina ceramics include alumina, glass containing alumina, and ceramic-glass composite material containing alumina, and are not particularly limited. Further, the constituents and compositions of the aluminum alloy are not particularly limited. The joined body of the present invention is used in various fields, and its use is not particularly limited.

In the present invention, the reason why the composition of the brazing alloy is limited as described above will be explained.

Mg reacts with alumina ceramics,
It has the function of forming a good bond and also has the function of reducing and decomposing the oxide film on the aluminum surface to improve the wetting by the wax. When Mg exceeds 10 wt%, oxidation by oxygen in the atmosphere becomes severe, the brazing property deteriorates, and defects such as voids occur at the joint. Mg is 2 wt
If it is less than%, the reaction with the alumina-based ceramics and the decomposition of the oxide on the surface of the aluminum alloy are insufficient, and the above effects cannot be obtained.

Ge and Si have the function of lowering the melting point of the wax. However, the total of Ge and Si is 10 wt%
If the melting point is lower than 600 ° C, the melting point of the brazing alloy cannot be lowered to 600 ° C or lower, and it becomes necessary to perform brazing at a temperature equal to or higher than or near the melting point of the aluminum alloy to be bonded, so that the bonding becomes impossible or the aluminum alloy Cause deterioration. Even when the Si content exceeds 15 wt%, the melting point of the wax rises, so that the same problem as described above occurs. Ge
If the content of Al exceeds 45 wt%, the brazing material itself becomes brittle and impractical, and the bridging also occurs in the joint after brazing, and the joint strength decreases.

[0018]

The melting point of the brazing alloy of the present invention is lower than that of the aluminum alloy, so that the alumina ceramics and the aluminum alloy can be directly bonded. At the time of this brazing, it is not necessary to subject the alumina-based ceramics to pretreatments such as metallizing treatment, chemical polishing, and plating.
Since it is not necessary to use a flux to remove the oxide on the surface of the aluminum alloy, the productivity is improved. In addition, since the joined body obtained by using the brazing alloy of the present invention is joined by a metal braze, it has higher strength, thermal conductivity, heat resistance, and airtightness than those joined by using an adhesive. It is also excellent in sex.

[0019]

Embodiments of the present invention will be described below.

Examples 1 to 5 and Comparative Examples 1 to 5 A brazing alloy composed of 25 wt% Ge, 12 wt% Si, 6 wt% Mg, and the balance Al was prepared. Using this brazing alloy, alumina ceramics and A1050 aluminum alloy were brazed in vacuum at a temperature of 550 ° C. and 5 × 10 ⁻⁴ torr.

1 and 2 are electron micrographs showing the metal structure of the joint interface of the obtained alumina ceramics-aluminum alloy joint. Note that FIG. 2 is an enlarged photograph of FIG. As shown in these figures, no defects such as voids are found at the bonding interface. When a shear load was applied parallel to the joint surface of the obtained joint body, the joint surface did not fracture until the alumina member fractured.

Similar to the above, braze alloys having various compositions shown in Table 1 were prepared and brazed to the alumina ceramics-
Table 1 also shows the results of preparing aluminum alloy joints and examining the brazing performance thereof.

[0023]

[Table 1] Example 6 A brazing alloy composed of 30 wt% Ge, 10 wt% Si, 5 wt% Mg, and the balance Al was prepared. As shown in FIG.
Using this braze alloy, an alumina pipe 1 and a disc 2 made of A6061 aluminum alloy were brazed to produce an insulating flange for vacuum equipment.

This insulating flange for vacuum equipment has good electrical insulation because the insulating member is made of ceramics. Further, since the fastening portion is made of aluminum alloy, it has sufficient mechanical reliability. Further, since the airtightness of the joint portion is high, no leak occurs even if the inside is highly vacuumed.

Example 7 25 wt% Ge, 8 wt% Si, 3 wt% Mg, balance A
A braze alloy consisting of 1 was prepared. As shown in FIG. 4, using this brazing alloy, a block 12 made of A1050 aluminum alloy was brazed onto an alumina substrate 11 to manufacture a heat sink for electronic devices.

This heat sink is excellent in heat conductivity because the joint portion is made of a metal mainly composed of aluminum.

[0027]

As described above in detail, by using the brazing alloy for joining of the present invention, the alumina ceramics and the aluminum alloy can be joined directly with high productivity. Further, the joined body of the present invention obtained by using this brazing alloy has high strength and is also excellent in thermal conductivity, heat resistance and airtightness.

[Brief description of drawings]

FIG. 1 is an electron micrograph showing a metal structure of a joint interface of an alumina ceramics-aluminum alloy joint obtained in Example 1 of the present invention.

FIG. 2 is an electron micrograph showing an enlarged metal microstructure of a joint interface of an alumina ceramics-aluminum alloy joint obtained in Example 1 of the present invention.

FIG. 3 is an exploded perspective view of an insulating flange for a vacuum device manufactured in Example 6 of the present invention.

FIG. 4 is an exploded perspective view of a heat sink for an electronic device manufactured in Example 7 of the present invention.

[Explanation of symbols]

1 ... Alumina pipe, 2 ... Aluminum alloy disc,
11 ... Alumina substrate, 12 ... Aluminum alloy block.

Claims (2)

[Claims] 1. A brazing alloy used for joining an alumina-based ceramic and an aluminum alloy, which is 5 to 45.
wt% Ge, 5-15 wt% Si, 2-10 wt%
2. A brazing alloy for joining, characterized by comprising Mg and the balance Al. 2. A joined body obtained by joining an alumina ceramics and an aluminum alloy by a brazing alloy, wherein the brazing alloy is 5 to 45 wt% Ge, 5 to 15 wt% Si, and 2 to 10 wt% Mg. A joined body comprising the balance Al.