JPH06203692A - Manufacture of contact material - Google Patents

Abstract

PURPOSE:To provide a contact material with sufficient joint strength for economical vacuum bulbs. CONSTITUTION:A molded body manufactured by press-molding a metal powder having a higher melting point than an infltrant 12 to form a prescribed shape and it is heated not oxidizing atmosphere to give a calcined body 2. A recessed part 2a is formed in the center of the lower face of the calcined body 2 and after a conductive matal 11 is put in the recessed part 2a, an infiltrant 12 is further put on the upper face of the metal. The resulting body is heated from the upper side at the melting point of the infiltrant 12 or higher temperature in not oxidizing atmosphere, so that the infiltrant is infiltrated into the calcined body 2 to obtain a contact material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a contact material for a vacuum valve.

[0002]

2. Description of the Related Art Conventionally, as a contact material for a vacuum valve, copper-molybdenum-niobium which is an infiltration type composite metal material disclosed in Japanese Patent Application Laid-Open No. 61-107619 and silver which has been conventionally known. There are composite metals such as tungsten carbide and copper-tungsten. FIG. 9 is a cross-sectional view showing an example of a manufacturing method for manufacturing a conventional composite metal such as copper-molybdenum-niobium. In the figure, 1 is a container made of alumina ceramic or carbon, 2 is a temporary sintered body made of molybdenum-niobium-copper, and 3 is a copper ingot. Temporary sintered body 2
Is obtained by mixing molybdenum powder, niobium powder and copper powder at a constant ratio, press-molding the mixture with a die having a predetermined shape, and then sintering the compact at 1000 ° C. After this,
A mass 3 of oxygen-free copper is placed on the pre-sintered body 2, and the oxygen-free copper 3 is impregnated into the pre-sintered body 2 at a temperature equal to or higher than the melting point of copper in a non-oxidizing atmosphere to obtain a contact material. The contact material thus obtained is machined into a predetermined shape and then bonded to an electrode rod by a silver brazing material made of a eutectic alloy of silver and copper for use.

[0003]

Although the conventional infiltration type contact material is made as described above, when the composition ratio of refractory metal such as molybdenum, niobium, tungsten carbide, and tungsten becomes large, silver Since the wettability with the brazing material is poor, there is a problem in that the brazing area is poor and sufficient bonding strength cannot be obtained.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for producing a contact material, which can obtain a sufficient bonding strength and is economical.

[0005]

According to the method of manufacturing a contact material according to the present invention, a recess is provided in the lower surface of the pre-sintered body, a conductive metal is placed in the recess, and the upper surface of the pre-sintered body is infiltrated. The material is arranged so that the infiltrant on the upper surface is impregnated into the pre-sintered body.

[0006]

In the method of manufacturing the contact material according to the present invention, since the conductive metal is arranged in the lower surface recess of the pre-sintered body,
Sufficient bonding strength with the electrode rod can be obtained through a commercially available silver brazing material.

[0007]

【Example】

Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a container made of alumina ceramic or carbon, 2 is a temporary sintered body made of molybdenum-niobium-copper, and 11 is a recess 2 at the center of the lower surface of the temporary sintered body 2.
A copper ingot which is a conductive metal disposed in a and 12 is a copper ingot (infiltration material) placed on the upper surface of the pre-sintered body 2.

Next, the operation will be described. Temporary sintered body 2
First, molybdenum powder, niobium powder and copper powder are respectively
Weighed in a ratio of 75.7 to 7.8 to 16.5, and then mixed for 2 hours, and subsequently, the mixed powder was filled in a predetermined mold and 2 ton /
Press molding is performed with a load of cm ² to form a disk-shaped molded body, which is sintered at 1000 ° C. to obtain a pre-sintered body 2. Next, the central portion of the lower surface of the pre-sintered body 2 is removed by cutting to provide a recess 2a, and a copper ingot 11 of oxygen-free copper having a shape that engages with the recess is arranged. 2, a copper lump 12 of oxygen-free copper is placed, and heated from above in a non-oxidizing atmosphere at a temperature equal to or higher than the melting point of copper to melt the copper lump 12 and impregnate it into the pre-sintered body 2. The contact material 13 shown is obtained.
In addition, 12a is an excess copper adhered to the outer peripheral portion.
The contact material 13 becomes the contact 14 shown in FIG. 3 by machining, and is used by brazing the portion 14a to an electrode rod (not shown) with a silver brazing material. The composition of the contact thus obtained has a molybdenum to niobium to copper ratio of 5
Although the ratio of the refractory metal is 4.4: 5.6: 40, which is large, the joint 14a is made of copper and has a very good wettability with the silver braze, so that sufficient joint strength can be obtained.

Example 2. Although the case where the contact composition is molybdenum-niobium-copper is described in the above-mentioned Example 1, in the case of silver-tungsten carbide, tungsten carbide is used as the temporary sintered body 2, and the conductive metal 11 is used.
By using a copper ingot of oxygen-free copper as the infiltration material 12 and silver as the infiltration material 12, the infiltration material 12 at a temperature equal to or higher than the melting point of silver is used.
Can be melted and impregnated to form the contact material 13. In this case, since the copper ingot 11 is used in the pre-sintered body 2, the required amount of silver can be greatly saved.
It can be a highly economical contact material.

Embodiment 3. In the second embodiment, the infiltration material 12
Shows the case of silver and the conductive metal 11 is copper. However, the same effect as in the above-described embodiment can be obtained by using silver alloy, copper alloy, etc., respectively.

Embodiment 4. In addition, in the above-described Example 1, an example was shown in which the concave portion at the center of the lower surface of the temporary sintered body 2 was removed by cutting the temporary sintered body 2. However, as shown in FIG. By providing 10a, the concave portion can be formed, and a more economical contact material can be provided.

Embodiment 5. Next, FIG. 5 shows an example in which the conductive metal 15 and the pre-sintered body 16 are coupled via the engaging portion 16a. That is, the conductive metal 15 and the pre-sintered body 16 are machined into, for example, a male screw shape and a female screw shape, and are screwed in. Then, infiltrate 12 in a non-oxidizing atmosphere.
The contact material 17 shown in FIG. 6 is obtained by melting the infiltrant 12 by heating from above in the melting point of above. The contact material 17 thus obtained has an engaging portion even if infiltration is not sufficiently performed or voids are present inside due to variations in infiltration temperature or the like. Therefore, the bonding strength can be further increased and the reliability can be increased.

Embodiment 6. Next, as another embodiment, FIG.
Figure 2 shows an example of a two-region contact. In the figure, 18 is a chromium calcinated body, 19 is a tungsten calcinated body, 20 is an oxygen-free copper lump, and 21 is an oxygen-free copper lump for infiltration. After 18 is sintered into a temporary sintered body, the central portion is removed by machining to form a cavity 18a, and 19 is also sintered to manufacture the temporary sintered body, and then the temporary sintered body is obtained. The exterior is machined to engage the top of the central cavity of 18. Further, after processing the copper mass 20 of oxygen-free copper so as to engage with the central part of the pre-sintered body 18, it is placed in the lower part of the cavity as shown in FIG.
An infiltration material 21 is placed on the upper surface. Then, these are heated and held in a non-oxidizing atmosphere at a temperature equal to or higher than the melting point of the infiltrant, and the infiltrant 21 is infiltrated into the pre-sintered bodies 18, 19. The contact material made in this way is processed as shown in FIG. In this contact point 22, a contact portion 22b is made of copper-tungsten, an outer peripheral portion 22c thereof is made of copper-chrome, and a joint portion 22a with an electrode rod is made of copper. The contact part of such a contact is made of a material with high withstand voltage and low welding, the outer peripheral part is a material capable of blocking a large current, and its joining is performed by an infiltrant, and since silver brazing or the like is not used, There is no rise of brazing material to the contact surface and there is no risk of contamination.
Further, since the joint portion with the electrode rod is copper, the jointability with the brazing material is also excellent. According to this method, various combinations are possible by changing the composition of the pre-sintered body according to the required electrical performance.

Example 7. In the above description, the example in which the central portion of the pre-sintered body 18 is removed by machining is given. However, if a cylindrical cavity is formed in advance at the molding stage, it is possible to further improve the economical efficiency.

[0015]

As described above, according to the present invention, since the portion made of the conductive metal is provided on one side of the contact, there is an effect that a good contact property and an economical contact material can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a state before infiltration of a contact material according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a state after infiltration of a contact material according to Example 1 of the present invention.

FIG. 3 is a cross-sectional view showing a contact material after machining according to Example 1 of the present invention.

FIG. 4 is a cross-sectional view showing a method for forming a pre-sintered body according to Example 4 of the present invention.

FIG. 5 is a sectional view showing a state before infiltration of a contact material according to a fifth embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a state after infiltration of a contact material according to Example 5 of the present invention.

FIG. 7 is a sectional view showing a state before infiltration of a contact material according to a sixth embodiment of the present invention.

FIG. 8 is a sectional view showing a contact material after machining according to Example 6 of the present invention.

FIG. 9 is a cross-sectional view showing a state before infiltration in a conventional contact material manufacturing method.

[Explanation of symbols]

 2 Temporary Sintered Body 2a Recess 11 Conductive Metal 12 Infiltrant 15 Conductive Metal 16 Temporary Sintered Body 16a Engagement Part 18, 19 Temporary Sintered Body 18a Cavity 21 Infiltrant

Claims (3)

[Claims] 1. A method for manufacturing a contact material by impregnating a temporary sintered body with an infiltrant having a lower melting point than that of the temporary sintered body,
By forming a recess in the center of the lower surface of the temporary sintered body, disposing a conductive metal in the recess, disposing an infiltrant on the upper surface of the temporary sintered body, and heating the upper surface infiltrant. A method for producing a contact material, which comprises impregnating the temporary sintered body to obtain a contact material. 2. The method for producing a contact material according to claim 1, wherein the pre-sintered body and the conductive metal arranged in the recessed portion are coupled via an engaging portion. 3. A method for producing a contact material by impregnating a temporary sintered body with an infiltrant having a melting point lower than that of the temporary sintered body,
A hollow is formed in the central portion of the temporary sintered body, and a temporary sintered body having a composition different from that of the temporary sintered body is arranged in the upper portion of the hollow portion, and a conductive metal is arranged in the lower portion. A method of manufacturing a contact material, comprising disposing an infiltrant on an upper surface of a pre-sintered body and impregnating the upper surface infiltrant into the pre-sintered body to obtain a contact material.