JP3106598B2 - Manufacturing method of electrode material - Google Patents

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 an electrode material having good brazing workability by using a fine powder of a copper-chromium alloy as a raw material by an atomizing method, and is particularly suitable for use as an electrode of a vacuum interrupter. .

[0002]

2. Description of the Related Art One of the important performances required as an electrode material of a vacuum interrupter is a high current interruption performance.

[0003] A copper (Cu) -chromium (Cr) alloy is known as an electrode material having an extremely excellent current interruption performance.
Conventionally, a mixture of copper powder manufactured by an electrolytic method and chromium powder manufactured by a pulverization method is compression-pressed and molded by a powder metallurgy method in which this is sintered at a high temperature. The method is general.

In this copper-chromium alloy, chromium is dispersed in a copper matrix. When attention is paid to the electrical characteristics as an electrode material, fine chromium is uniformly dispersed in the copper matrix. Is more preferred.

However, in the case of a conventional copper-chromium alloy produced by powder metallurgy, the width of the particle size distribution of chromium powder obtained by mechanical pulverization by a pulverization method is very large, and the average particle diameter is large. Since it reaches about 40 μm, there is a drawback that when mixing the copper powder and the chromium powder, uniform mixing is difficult due to the difference in specific gravity, the particle size of the powder, or the difference in particle size distribution. As a result, chromium in the copper matrix after sintering was not finely and uniformly dispersed, and the electrical characteristics were not as good as expected.

Accordingly, the present inventors have proposed an electrode material obtained by sintering an alloy fine powder of copper and chromium obtained by an atomizing method, and chromium having a fine particle diameter is uniformly dispersed in a copper matrix. A high quality copper-chromium alloy was successfully obtained.

The electrode material obtained by sintering the alloy fine powder of copper and chromium obtained by the atomizing method has a narrow sinterable temperature range, and the obtained electrode material is a porous material having minute voids. Therefore, in a brazing material generally used in a brazing operation when manufacturing a vacuum interrupter or the like, a part of the brazing material may penetrate into the inside of the electrode material, and there is a fear that a brazing defect may be caused. Attempts have been made to integrate them by mechanical caulking or by using special brazing materials.

[0008]

In the case of a method in which the electrode of the vacuum interrupter and the lead bar are mechanically caulked and integrated, a new caulking step is required, which lowers productivity and increases manufacturing cost. In addition, it has a drawback that its long-term reliability is inferior to the method of brazing them.

In the case of the method of brazing the electrode of the vacuum interrupter and the lead rod, it is necessary to use a special brazing material, and thus the use of such a brazing material causes an increase in manufacturing cost. There is.

[0010]

An object of the present invention is to provide a method for producing an electrode material of a copper-chromium alloy by an atomizing method which can be brazed to a lead rod of a vacuum interrupter using a general brazing material. With the goal.

[0011]

According to a method of manufacturing an electrode material according to the present invention, an alloy fine powder of copper and chromium obtained by an atomizing method is heated and sintered in a non-oxidizing atmosphere.
After the brazing portion of the electrode material obtained by this is machined, a surface treatment layer for brazing is formed on the brazing portion.

Here, as the surface treatment layer for brazing, it is preferable that copper or nickel having a thickness of 1 to 50 μm is formed by plating, vapor deposition, thermal spraying or the like. Is manufactured, the portion of the electrode material on which the surface treatment layer is formed and the lead bar are brazed using a general brazing material.

When the thickness of the copper or nickel is less than 1 μm, the effect of suppressing the infiltration of the brazing material due to the formation of this surface treatment layer cannot be obtained. On the other hand, if the thickness of the copper or nickel is more than 50 μm, an increase in processing time due to the increase in processing time cannot be avoided. The contact resistance value at the interface increases.

[0014]

The fine powder of the copper-chromium alloy obtained by the atomizing method is sintered in a non-oxidizing atmosphere, and the brazing portion of the electrode material thus obtained is machined and then brazed to the brazing portion. By forming the surface treatment layer described above, the minute void portions existing in the brazed portion of the electrode material are filled.

As a result, the brazing material cannot penetrate into the electrode material due to the surface treatment layer, and good brazing can be performed without causing brazing failure due to shortage of the brazing material.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A vacuum interrupter is shown in FIG. 2 which shows an example of a schematic structure of the vacuum interrupter. Electrodes 13 and 14 are respectively provided on opposing end surfaces of a pair of lead rods 11 and 12 which are linear with each other. It is provided integrally via a brazing material (not shown). A central portion of the outer periphery of a cylindrical shield 15 surrounding the electrodes 13 and 14 is held in a state sandwiched between a pair of insulating cylinders 16 and 17 surrounding the shield 15.
The one lead bar 11 is integrally fixed to the metal end plate 18 in a state where the lead rod 11 air-tightly penetrates the metal end plate 18 joined to one end of the one insulating cylinder 16. The other lead rod 12 connected to a drive device (not shown) is connected via a bellows 20 to the other metal end plate 19 airtightly joined to the other end of the other insulating cylinder 17, and is driven by the operation of the drive device. The movable electrode 14 opens and closes with respect to the fixed electrode 13 so as to be able to reciprocate in the direction opposite to the electrodes 13 and 14.

The electrodes 13 and 14 in this embodiment are:
The main part is composed of a copper-chromium alloy obtained by sintering a raw material by an atomizing method.

An example of the method for producing this electrode material according to the present invention will be described below. A mixture of copper and chromium is melted in a non-oxidizing atmosphere such as a vacuum, and the molten metal is melted at 5 to 8 MPa (megapascal). It is rapidly cooled and solidified by a gas atomization method using argon (Ar) gas at a pressure to obtain a fine powder, and a fine powder of a copper-chromium alloy in which chromium is dispersed in a copper matrix is obtained.

In carrying out the above method, the weight ratio of copper and chromium in the mixture of copper and chromium before melting was set to 4: 1. If the weight ratio of chromium is larger than this, copper dispersed in a chromium matrix is generated, and a target copper-chromium alloy powder cannot be obtained.

When the mixture of copper and chromium is melted, copper and chromium having a low oxygen content are selected in order to reduce the oxygen content of the molten metal, while melting in a non-oxidizing atmosphere as described above. Or deoxidize to an oxygen content of 100
It was suppressed to 0 ppm or less. In this case, the presence of unavoidable impurities, such as iron (Fe) and nickel (Ni), mixed in the raw materials and the like was allowed.

The copper-chromium alloy fine powder thus obtained had a particle size of 150 μm or less, and its component ratio was equivalent to that of the original mixture of copper and chromium. Also, as a result of observing this copper-chromium alloy fine powder with an electron microscope, 5
It was confirmed that the chromium particles having a size of μm or less were uniformly dispersed in the copper matrix.

As shown in FIG. 1 showing the manufacturing procedure according to the present embodiment, 300 g of this copper-chromium alloy fine powder A was filled into an alumina ceramic container B having an inner diameter of 70 mm, and then 5 × 10 ^-5 Torr. The material was heated at 1080 ° C. for 30 minutes in a vacuum and sintered to obtain an electrode material C having a packing density of 85%. In addition, this packing density ratio is obtained by dividing the actual mass of the copper-chromium alloy per unit volume by the theoretical mass per unit volume of an ideal copper-chromium alloy containing no bubbles or the like, and dividing 100 by this. This is the value obtained by multiplication.

The average particle diameter of chromium in the electrode material C made of a copper-chromium alloy containing 20% by weight of chromium thus obtained is 10 μm, and the distribution width of the particle diameter is narrow.
It was confirmed that they were uniformly dispersed.

After that, the electrode material C was removed to a diameter of 60 mm.
Then, a copper plate E having a thickness of 5 μm is applied to one end face to which the lead rods 11 and 12 shown in FIG. 1 are brazed, and finally, as shown in FIG. The shapes of the electrodes 13 and 14 were finished. Then, a copper-manganese (Mn) -nickel (Ni) -based brazing material having a thickness of 0.1 mm is used.
Heat treatment was performed at 960 ° C. for 15 minutes in a vacuum of × 10 ⁻⁴ Torr, and the lead rods 11 and 12 and the electrodes 13 and 14 were brazed.

The lead rod 1 thus brazed
When the brazing portions were cut so as to intersect the brazing portions 1 and 12 and the electrodes 13 and 14, and the state of the brazing portions was observed, the penetration of the brazing material into the electrodes 13 and 14 was suppressed. Was confirmed.

Similar results were obtained for the electrodes 13 and 14 plated with nickel having a thickness of 5 μm under the same conditions as in the above-described embodiment.

[0027]

According to the method for producing an electrode material of the present invention,
The alloy fine powder of copper and chromium obtained by the atomizing method is heated and sintered in a non-oxidizing atmosphere, and the brazed portion of the electrode material obtained by this is machined, and then the brazed portion is brazed. Since the surface treatment layer for attachment was formed, the minute voids existing in the brazing portion of the electrode material were filled with the surface treatment layer. It is not possible to penetrate into the inside of the solder, and good brazing can be performed without causing brazing failure due to shortage of brazing material or the like.

Therefore, it is possible to use the sintered body made of the copper-chromium alloy by the atomizing method as a raw material without any problem as an electrode of a vacuum interrupter, and to compare with the copper-chromium alloy by the conventional sintering metallurgy method. As a result, it is possible to provide an electrode material excellent in breaking current value, contact resistance value, welding resistance and the like.

[Brief description of the drawings]

FIG. 1 is a process chart showing one embodiment of a method for producing an electrode material according to the present invention.

FIG. 2 is a cross-sectional view illustrating an example of a vacuum interrupter.

[Explanation of symbols]

A is a fine powder of copper-chromium alloy, B is a container, C is an electrode material,
D is a disk, E is copper plating, 11 and 12 are lead bars, 13,
14 is an electrode.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshina Fukai 2-1-1-17 Osaki, Shinagawa-ku, Tokyo Inside Meidensha Co., Ltd. (56) References JP-A-53-146904 (JP, A) 57-67141 (JP, A) JP-A-55-151727 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01H 33/66 H01H 11/04-11/06 C22C 9 / 00

Claims (3)

(57) [Claims] 1. An alloy fine powder of copper and chromium obtained by an atomizing method is heated and sintered in a non-oxidizing atmosphere, and a brazed portion of an electrode material obtained by this is machined. A method for manufacturing an electrode material, comprising forming a surface treatment layer for brazing on a brazing portion. 2. A surface treatment layer for brazing having a thickness of 1 to 50 μm.
2. The method for manufacturing an electrode material according to claim 1, wherein the thickness of the electrode material is copper. 3. The method according to claim 1, wherein the surface treatment layer is made of nickel having a thickness of 1 to 50 μm.