JPH0642348B2 - Contact for vacuum circuit breaker - Google Patents

Description

The present invention relates to a contact for a vacuum circuit breaker.

[Conventional technology]

Generally, contact alloys produced by the powder sintering method use powders of several kinds of metals or intermetallic compounds as raw materials, thoroughly mix them by a mechanical method, press them at a predetermined molding pressure, and then sinter them in a high temperature atmosphere. Made. The contact alloy thus obtained is processed into a predetermined shape and then bonded and fixed to an electrode rod made of a material having good conductivity such as copper for use. As a method for attaching the contact to the electrode rod, hard brazing using a Cu-Ag-based or Cu-Au-based brazing material in a hydrogen atmosphere or in vacuum is generally used. However, in the case of such an alloy having poor bondability with a hard solder, and as a method of reducing the amount of the contact material used, there are the following methods.

FIG. 2 is a cross-sectional view showing a conventional contact base plate composed of two layers as disclosed in, for example, Japanese Patent Application No. 57-212410, in which (1) is a main contact material and (1a) is a peripheral stand. The lower part (2) is a base metal made of a conductive material such as copper, and is manufactured by shaving a copper rod, for example. (2a) is a main metal part, and (2b) is a brim part.

Next, the manufacturing method thereof will be described. The main contact material (1) made by mixing multiple kinds of metal powders is
Including (2), it is usually pressed at a molding pressure ( ² ton / cm ² ) or more, and it is contact-reacted at high temperature until contact sintering, and at the same time as contact sintering, adhesion with base metal (2) It is to do. The main base metal part (2a) of the collar part (2b) is positioned at the center of the main contact material (1) during molding, and the main contact material (1) is separated from the main base metal part (2a) after molding. Prevent. Also, when the contacts are sintered, the main contact material (1) shrinks so as to wrap the base metal (2) by sintering, but at the time of molding, the flange (2b) makes the peripheral lower part (1a) a uniform thickness. As a result, the peripheral lower part (1a) prevents the adhesion failure from occurring easily due to cracks.

[Problems to be solved by the invention]

The conventional two-layer contact is manufactured as described above, and a high molding pressure must be applied to suppress the contraction of the main contact material during sintering. Since the molding pressure is limited, the shrinkage rate increases, and as shown in Fig. 3, cracks (C) occur due to shrinkage of the main contact layer during sintering,
Further, when the adhesion between the main contact layer and the base metal is low, the crack (C) penetrates deep into the inside of the contact, making it difficult to form a two-layer contact having a large diameter. Further, since the conductive metal component mainly contained in the main contact material and the base metal adhere to each other due to a contact reaction during sintering, the adhesive force was weaker as the conductive metal component in the main contact portion was smaller.

Further, as shown in Japanese Patent Application No. 58-165377, there is a two-layer contact by using a second contact powder in place of the base metal, and the main contact material and the second contact material are joined together. Although it was performed satisfactorily at a low molding pressure, when the main contact layer contained a large amount of low melting point metal, some low melting point metal diffused into the second metal contact material after sintering, and brazing with the electrode rod. If the main contact material has a low sintering temperature, the second contact material will not be sintered and the strength will be weakened.

The present invention has been made to solve the above problems, and an object thereof is to economically produce a multilayer contact having sufficient strength even for a large contact diameter.

[Means for solving problems]

The contact for a vacuum circuit breaker according to the present invention has a conductive metal component similar to that of the base metal so that adhesion can be obtained between the main contact layer made of metal powder and the base metal during contact molding by sintering. The intermediate layer is made of a metal powder containing a large amount of metal.

[Action]

According to the present invention, the intermediate layer is formed by using the same conductive metal component as that of the base metal in a large amount, the adhesion with the base metal can be ensured, and the sintering from the metal powder together with the main contact layer is ensured. By forming in (1), the bondability with the main contact layer can be obtained, and a multilayer contact having sufficient strength can be obtained.

Example of Invention

An embodiment of the present invention will be described below with reference to the drawings. First
In the figure, (1) is a main contact material made of a mixture of a conductive metal powder or a refractory metal powder, and (2) is, for example, Cu or Ag.
An alloy made of a conductive material such as a conductive metal or a conductive alloy, such as (2a) is the main base metal part of the base metal (2), (2b) is a collar around the main base metal part (2a). It is a brim formed on the top.

Similar to the main contact material (1), (3) is formed of a mixture of conductive metal powder or refractory metal powder, etc., and the base metal (2) in consideration of the adhesiveness with the base metal (2). An intermediate layer made of a material containing a large amount of conductive metal components, such as copper, similar to (3
a) is the peripheral lower part of this intermediate layer (3).

Further, (4) is a conductive rod brazed to the base metal (2).

The main contact material (1) used in the present invention, that is, the second contact material, is a conductive metal powder such as Cu or Ag,
A mixture with a refractory metal powder such as Cr, Co or Fe can be used. If necessary, Bi, Te, Sb, Bi
₂ O _{3, Te} 2 _O low-melting metal or intermetallic compound such as _3, or sometimes added oxide.

These metal powders are used after being thoroughly mixed by a blender.

The intermediate layer (3) used in the present invention, that is, the first contact material, is a conductive metal powder such as Cu or Ag, and C
Examples include a mixture with a refractory metal powder such as r, Co, and Fe. These metal powders are also used after being thoroughly mixed by a blender.

As described above, the conductive materials contained in the materials of the main contact material (1), the base metal (2), and the intermediate layer (3) are preferably composed of the same material in terms of adhesion.

Molding is performed in the following order.

Place the powder material of the intermediate layer (3) on the base metal (2), 0.5 ~ 2
After primary molding at a molding pressure of t / cm ² , the main contact material (1) is placed and secondary molding is performed at a molding pressure of 4 to 8 ton / cm ² . In this case, the secondary molding pressure needs to be at least twice as much as the primary molding pressure in order to obtain the temporary bonding strength between the three layers until sintering after molding. The obtained molded product (one body) is fired at the sintering temperature of the main contact material, and the main contact layer is processed into a shape in which the main contact surface is on the main contact surface and the base metal is hard soldered to the electrode rod. Circuit breaker contacts are manufactured.

In the multilayer contact thus manufactured, the main contact material (1) and the intermediate layer (3) are both powder, so the adhesion between both layers is better than that of solid and powder, and the intermediate layer (3 The adhesive property between the intermediate layer (3) and the base metal (2) is improved due to the large amount of the conductive material component (4), and as a result, a good contact can be manufactured even when the molding pressure is low. Regarding strength, main contact material (1)
In comparison with the case of only the intermediate layer (3), it can be sufficiently reinforced by the base metal (2). Even when the main contact material (1) contains a large amount of a low melting point metal such as Bi, the diffusion of the main contact material (1) is caused by the intermediate layer (3).
Since it remains only up to this point, the base metal (3) can be easily brazed to the electrode rod or the like by using a hard solder or the like.

In the above example, the powder material of the intermediate layer (3) was placed,
Although the case of primary molding with a molding pressure of 0.5 to ² t / cm ² was given,
1 to 0.5 to ² ton / cm ² in advance for the size of the main metal part (2a)
The same effect can be obtained by using a molded body that is molded next.

〔The invention's effect〕

As described above, according to the contact for a vacuum circuit breaker according to the present invention, at the time of contact molding by sintering, between the main contact layer and the base metal made of metal powder, the base metal, and further the main contact layer In order to improve adhesion and bondability, an intermediate layer made of metal powder containing a large amount of conductive metal component similar to that of the base metal is provided. Even if it has a contact diameter, it has an excellent effect that a multilayer contact which can secure sufficient strength can be economically produced.

[Brief description of drawings]

FIG. 1 is a sectional view showing a multilayer contact according to an embodiment of the present invention, FIG. 2 is a sectional view showing a conventional two-layer contact, and FIG.
It is sectional drawing which shows the crack by the contraction of the contact layer after layer contact sintering. In the figure, (1) is the main contact material, (1a) is the peripheral lower part, (2)
Is a base metal, (3) is an intermediate layer, and (4) is a conductive rod. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (3)

[Claims] 1. A base metal, which is made of a conductive metal or a conductive alloy and is brazed to a conductive rod, and a plurality of kinds of metal powders provided on the surface of the base opposite to the brazing surface are mixed. And a second contact material which is provided on a surface of the first contact material opposite to the base metal joining surface and which is formed by mixing a plurality of kinds of metal powders. It is formed by using, as the first contact material, a material having a large amount of conductive metal component similar to that of the base metal, and sintering the first contact material and the second contact material integrally with the base metal. A contact for a vacuum circuit breaker, which is characterized in that 2. The contact for a vacuum circuit breaker according to claim 1, wherein the base metal is made of copper, silver or an alloy thereof. 3. The contact for a vacuum circuit breaker according to claim 1, wherein the second contact material contains a low melting point metal as a component.