JP3067318B2 - 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 from a fine powder of a copper-chromium alloy 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.

[0004] In addition, an infiltration method in which chromium is infiltrated into voids of the compression-pressed copper powder, or a mixed powder of copper and chromium is compression-pressed and fired at a low temperature. After sintering, a method of infiltrating copper into the voids or a method of casting has been attempted.

[0005]

This copper-chromium alloy has chromium dispersed in a copper matrix. However, when attention is paid to the electrical characteristics as an electrode material, fine chromium is contained in the copper matrix. It is preferable that they are uniformly dispersed.

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.

[0007] Therefore, it is conceivable to further mechanically pulverize the chromium powder to reduce its particle size. In this case, the surface of the chromium powder is oxidized during the pulverization process and during storage, and oxygen-containing powder is contained. There is also a problem that the sinterability is reduced as the amount increases. It is also conceivable to classify the chromium powder obtained by the pulverization method by sieving and use only the chromium powder having a fine diameter. However, in this method, the yield is extremely deteriorated and the production cost is increased.

[0008] On the other hand, conventional copper produced by the infiltration method
In the case of a chromium alloy, chromium powder is easily oxidized, so it is necessary to thoroughly control its quality, and chromium powder having an oxidized surface has poor wettability with copper and has a disadvantage that it cannot be infiltrated.

In the case of a conventional copper-chromium alloy produced by a casting method, chromium particles in a copper matrix grow due to a low cooling rate during solidification, and uniform and fine chromium is dispersed. In addition to the difficulty, there is a disadvantage that the quality of the obtained copper-chromium alloy is apt to vary due to the tendency of solidification segregation.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a high-quality copper-chromium alloy electrode material in which fine chromium is uniformly dispersed in a copper matrix.

[0011]

SUMMARY OF THE INVENTION The present inventors have manufactured a fine powder of a copper-chromium alloy by an atomizing method without using a mechanical pulverizing method of chromium, which is difficult to miniaturize and has a problem of surface oxidation. Then, this was sintered to examine whether it was possible to produce an electrode material.

Therefore, a mixture of copper and chromium is melted in a non-oxidizing atmosphere such as vacuum, and the molten metal is rapidly solidified by a gas atomization method using argon (Ar) gas at a pressure of 5 to 8 MPa (megapascal). In this way, a fine powder of a copper-chromium alloy in which chromium was dispersed in a copper matrix was 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 melting a mixture of copper and chromium, 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.

[0015] The particle size of the copper-chromium alloy fine powder thus obtained was 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.

The method for producing an electrode material according to the present invention has been made in view of the above-mentioned knowledge, and the method for producing an alloy fine powder of copper and chromium obtained by the above-mentioned atomizing method is 100%.
After filling in a soft metal container that does not melt at 0 ° C. or less, and performing hot extrusion at a heating temperature of 950 ± 50 ° C. for each container, the portion of the container is removed. It is assumed that.

Here, as the soft metal that does not melt at 1000 ° C. or lower, mild steel, stainless steel, copper, or the like can be used.

[0018]

In the copper-chromium alloy fine powder obtained by the atomization method, chromium having a small particle diameter is uniformly dispersed in a copper matrix. This is filled in a soft metal container that does not melt at 1000 ° C. or less, and the container is 950 ± 50
By performing the hot extrusion at a heating temperature of ° C., the alloy powder is sintered and integrated at a high density. Thereafter, the portion of the container is removed and the sintered copper-chromium alloy is taken out.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A vacuum interrupter is shown in FIG. 1 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 form a straight line. 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.

In the present embodiment, the electrodes 13 and 14 are:
The raw material by the atomizing method is filled in a soft metal container, and the container is subjected to hot extrusion at a heating temperature of 950 ± 50 ° C., and a main part is formed of a sintered body of a copper-chromium alloy obtained by this. .

An example of a method for producing the electrodes 13 and 14 according to the present invention is as follows. 3.5 μm) with a length of 170 mm
After filling into a mild steel capsule having an outer diameter of 70 mm and a wall thickness of 3 mm, the mild steel capsule was hot-extruded at 950 ° C., the diameter was reduced to 45 mm, and the internal atomized powder was sintered and integrated. . Next, to remove the capsule portion, it was processed into a billet having a length of 160 mm and a diameter of 36 mm, and then machined into a predetermined electrode shape as shown in FIG.

The average particle diameter of chromium in the copper-chromium alloy containing 20% by weight of chromium thus obtained was 10 μm, and the distribution width of the particle diameter was narrow, and it was confirmed that the chromium was uniformly dispersed. did. The conductivity (IACS) is 6
0%, and the density filling rate was 99%. The density filling rate 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 and the like.
This is a value obtained by multiplying 00.

This copper-chromium alloy was machined into a predetermined electrode shape, incorporated into a vacuum interrupter shown in FIG. 1 and compared with a conventional one. As a result, the chromium was uniformly dispersed, and the It was found that the diffusion was smooth and the breaking performance was improved. In addition, the contact resistance was reduced with the refinement of chromium, and the welding resistance was also reduced.

[0024]

According to the method for producing an electrode material of the present invention,
The copper-chromium alloy fine powder obtained by the atomizing method is filled into a soft metal container that does not melt at 1000 ° C. or less, and after hot-extruding at a heating temperature of 950 ± 50 ° C. for each container, Since the portion of the container is removed, a high-quality copper-chromium alloy in which chromium having a fine particle diameter is uniformly dispersed in a copper matrix can be obtained. As compared with a chromium alloy, it is possible to provide an electrode material having excellent breaking current value, contact resistance value, welding resistance and the like.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of a vacuum interrupter.

[Explanation of symbols]

 11 and 12 are lead rods, and 13 and 14 are electrodes.

Continuation of 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) JP-A-60- 141802 (JP, A) JP-A-49-53104 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01H 33/66 H01H 1/02 H01H 11/04 B22F 5/00

Claims (1)

(57) [Claims] 1. An alloy fine powder of copper and chromium obtained by an atomizing method is filled in a soft metal container that does not melt at 1000 ° C. or less, and the container is heated at a heating temperature of 950 ± 50 ° C. A method for producing an electrode material, wherein a portion of the container is removed after performing an extrusion process.