JPH05198230A - Manufacture of electrode material - Google Patents

Abstract

PURPOSE:To provide a method for easily manufacturing an electrode material, with excellent reproducibility, whose contact-resistance value is low and whose weld-resisting performance is excellent without difficulty by adding a low fusion- point metal to a copper-chromium alloy. CONSTITUTION:An electrode material is manufactured by compounding the micro-powder of copper and chromium obtained through an atomizing method with the micro-powder of an alloy of copper and metal having its fusion point lower than that of this copper and that is obtained through the atomizing method, and then heating the inter-compounded micro-powder to be sintered in a non-oxidizing atmosphere.

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 using a fine metal powder as a raw material by an atomizing method in which a metal having a melting point lower than that of copper is added to a copper-chromium alloy, and more particularly to a vacuum interrupter electrode. It is suitable for use in.

[0002]

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

A copper (Cu) -chromium (Cr) alloy is known as an electrode material having an excellent current cut-off performance. Conventionally, a copper powder produced by an electrolytic method or the like and a pulverizing method or the like are used. A general method is a powder metallurgical method in which a mixture of the chrome powder produced by (1) and (2) is compression-pressed and sintered at high temperature.

This copper-chromium alloy is one in which chromium is dispersed in a copper matrix, and when attention is paid to the electrical characteristics as an electrode material, fine chromium is uniformly dispersed in the copper matrix. Is preferred.

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

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 storage, and oxygen content is increased. There is also a problem that the sinterability decreases as the amount increases. It is also conceivable to classify the chrome powder obtained by the pulverizing method by sieving and use only the chrome powder having a fine diameter. However, this method causes extremely low yield and causes an increase in manufacturing cost.

For these reasons, the present inventors have manufactured a fine powder of a copper-chromium alloy by the atomization method without adopting the mechanical pulverization method of chromium, which is difficult to miniaturize and has the problem of surface oxidation. Proposing a method for producing an electrode material by sintering this, and obtaining copper-chrome in which chromium having a fine particle size is uniformly dispersed in a copper matrix, copper- It has become possible to provide an electrode material having a greatly improved breaking current value as compared with a chromium alloy.

[0008]

[Problems to be Solved by the Invention] Even if a copper-chromium alloy which can be excellent in current interruption performance is manufactured by a sintering method using a raw material by an atomizing method, another electrode is used. Compared with the materials, it cannot be said that they are sufficient in terms of contact resistance and welding resistance.

Therefore, a fine powder of a copper-chromium alloy produced by this atomization method is mixed with a powder of a low melting point metal such as bismuth (Bi) which can reduce the contact resistance value and improve the welding resistance performance. It was attempted to obtain an electrode material having a large breaking current value, a low contact resistance value, and an excellent welding resistance, etc., by heating and sintering.

In this method, however, the low melting point metal evaporates and scatters significantly during the heating step during sintering, and when the fine powder of the copper-chromium alloy and the low melting point metal powder are mixed by the atomizing method, this low melting point metal is mixed. It is necessary to set these ratios in consideration of the scattering of the melting point metal. Moreover, since the mixing ratio of the low melting point metal to the fine powder of the copper-chromium alloy is several percent or less, it is extremely difficult to mix these uniformly and without variation, and the manufacturing process becomes complicated. Further, it was found that the proportion of the low melting point metal in the electrode material obtained thereby was poor in reproducibility and it was difficult to keep the quality constant.

[0011]

An object of the present invention is to provide a method capable of easily and reproducibly producing an electrode material having a low contact resistance value and a good welding resistance by adding a low melting point metal to a copper-chromium alloy. The purpose is to

[0012]

Means for Solving the Problems The inventors of the present invention can produce an electrode material by atomizing copper and chromium into an alloy fine powder by an atomizing method and heating the alloy in a non-oxidizing atmosphere for sintering. Focusing on the fact that it is possible, alloy fine powder of copper and a metal having a lower melting point than copper by an atomizing method, and mixing the fine powder of these copper-low melting point metal and the fine powder of copper-chromium alloy by the atomizing method Then, it was examined whether or not the electrode material could be manufactured by heating and sintering these in a non-oxidizing atmosphere.

Therefore, a refractory containing a copper ingot is used.
Arrange the crucible with argon (Ar) gas or nitrogen (N ₂) Gas or vacuum
Heated to 1200 ° C in a non-oxidizing atmosphere of
Melt the copper in the refractory crucible and then
Put chrome-shaped chrome into this refractory crucible and
Copper and chromium by heating to 1700 ° C in a non-oxidizing atmosphere
After obtaining a mixed molten metal with
Sprayed at a pressure of 8MPa and chromium with a particle size of 150μm or less
Of copper-chromium alloy with an average particle size of 3.5 μm
Mize powder was obtained.

On the other hand, 30% by weight of bismuth (Bi) was added to copper which was heated and melted at 1200 ° C. in a refractory crucible to obtain a mixed molten metal of copper and bismuth, which was then treated with argon gas. Sprayed at a pressure of 5-8MPa and the particle size is 1
Atomized powder of copper-bismuth alloy having a particle size of 00 μm or less was obtained. When the atomized powder was chemically analyzed, the bismuth content was 25% by weight.

When melting copper and chromium and copper and bismuth, respectively, copper, chromium and bismuth having a low oxygen content are selected in order to reduce the oxygen content of the molten metal, while the above-mentioned non-oxidation is carried out. The oxygen content was suppressed to 1000 ppm or less by melting in a neutral atmosphere or by performing deoxidation treatment. In this case, the presence of inevitable impurities, such as iron (Fe) and nickel (Ni), mixed in the raw materials was allowed.

Thereafter, the above-mentioned atomized powder of copper-chromium alloy and atomized powder of copper-bismuth alloy are mixed so that the proportion of bismuth is 0.5% by weight, and this mixed powder is mixed with gold having a diameter of 50 mm. Fill the mold, 3.5 tons / c
After press-molding into a disk shape with a pressure of m ² , this is 5 × 10
Sintered by heating at 1080 ° C. for 30 minutes in a ⁻⁵ Torr vacuum furnace. Table 1 shows the results of measuring the bismuth content contained in this sintered body for each of the 10 samples as the method of the present invention. As a result of observing the structure of this sintered body with an electron microscope, it was confirmed that chromium particles of 5 μm or less were uniformly dispersed in the copper matrix.

For comparison, copper-chromium alloy fine powder obtained by the same method as the atomizing method described above and 0.5% by weight of bismuth powder with respect to this copper-chromium alloy fine powder are mixed. Then, this was filled in a mold having a diameter of 50 mm, pressure-molded into a disk shape with a pressing force of 3.5 tons / cm ² , and then this was molded in a vacuum of 5 × 10 ⁻⁵ Torr for 10 minutes for 30 minutes.
Table 1 also shows the results of measuring the bismuth content of each of the 10 samples when heated and sintered at 80 ° C. (hereinafter, this manufacturing method is referred to as a powder addition method). Show.

Further, a copper powder, a chromium powder and a bismuth powder in a proportion of 0.5% by weight relative to these are mixed, and the mixed powder of copper, chromium and bismuth obtained by this is mixed to have a diameter of 50 mm. Filled into the mold of 3.5 tons / cm ²
After press-molding into a disk shape with a pressing force of 5 × 10
The content of bismuth contained in this sintered body when heated and sintered at 1080 ° C. for 30 minutes in a vacuum of ⁻⁵ Torr for each of 10 samples The measured results are also shown in Table 1.

[0019]

[Table 1]

As is clear from the above results, it was found that the method of the present invention is less likely to cause bismuth to scatter than the powder addition method and the conventional method, and the bismuth ratio is less uneven.

The method for producing the electrode material according to the present invention is based on the above-mentioned consideration and test, and includes copper and chromium alloy fine powder obtained by the atomizing method,
It is characterized in that copper obtained by the atomizing method and alloy fine powder of a metal having a melting point lower than that of copper are mixed, and these are heated and sintered in a non-oxidizing atmosphere. ..

Here, a metal having a melting point lower than that of copper and capable of lowering the contact resistance value of the electrode material to improve the welding resistance performance (hereinafter, referred to as
This is called a low melting point metal), bismuth (B
It is possible to adopt one or more of i), antimony (Sb), tellurium (Te), selenium (Se), and lead (Pb).

When the ratio of these low melting point metals to copper and chromium is less than 0.02%, it is expected that the addition of the low melting point metal will lower the contact resistance value and improve the welding resistance performance. Can hardly do. On the contrary, if the low melting point metal is added in an amount of more than 3.0% by weight, the current cut-off performance is abruptly deteriorated. Therefore, it is desirable that the ratio of these low melting point metals to copper and chromium is in the range of 0.02 to 3.0% by weight.

Further, when the fine alloy powder of copper and low melting point metal is produced by the atomization method, if the ratio of the low melting point metal to copper is less than 10%, the alloy fineness of the copper and low melting point metal is reduced. The mixing ratio of the powder has to be set to a large amount with respect to the fine alloy powder of copper and chromium, and there is a possibility that the ratio of copper is increased as a whole and the barrier performance is deteriorated. On the contrary, when the low melting point metal in an amount exceeding 50% by weight is added, the amount of the low melting point metal scattered remarkably increases during the production of the alloy fine powder of the copper and the low melting point metal. A low melting point metal precipitates and a concentration difference occurs in the content of the low melting point metal existing between the crystal grains of copper, and a uniform alloy fine powder cannot be obtained. Therefore, the ratio of the low melting point metal to copper at the time of producing an alloy fine powder of copper and the low melting point metal is 10% to 50%.
It is desirable to stay within the range.

[0025]

In the fine copper-chromium alloy powder obtained by the atomizing method, chromium having a fine particle size is uniformly dispersed in the copper matrix. Further, in the copper-low melting point metal alloy fine powder obtained by the atomization method, the low melting point metal having a fine particle size is uniformly dispersed in the copper matrix. By uniformly mixing and heating these, the metal crystal particles are densely sintered and integrated without coarsening.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A vacuum interrupter is as shown in FIG. 1 showing an example of a schematic structure thereof, and electrodes 13 and 14 are provided on opposite end faces of a pair of lead rods 11 and 12 which are in a straight line with each other. They are integrally joined via a brazing material (not shown). A central portion of the outer circumference of a cylindrical shield 15 that surrounds the electrodes 13 and 14 is held in a state of being sandwiched between a pair of insulating cylinders 16 and 17 that surrounds the shield 15.

One of the lead rods 11 is integrally fixed to the metal end plate 18 in a state where the metal end plate 18 joined to one end of the one insulating cylinder 16 is hermetically penetrated. Further, the other lead rod 12 connected to the drive device (not shown) is connected to the other metal end plate 19 airtightly joined to the other end of the other insulating cylinder 17 via the bellows 20 to operate the drive device. Accordingly, the movable-side electrode 14 opens and closes with respect to the fixed-side electrode 13 so that the electrodes 13 and 14 can reciprocate in opposite directions.

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

An example of the method for producing the electrodes 13 and 14 according to the present invention will be described below. Atomized powder of copper-chromium alloy is obtained by the same method as described above, while heating to 1200 ° C. in a refractory crucible. 27% by weight of lead (Pb) was added to the molten copper to obtain a molten mixture of copper and lead, which was then sprayed with argon gas at a pressure of 5 to 8 MPa so that the particle size was 100 μm. The atomized powder of the following copper-lead alloy was obtained. Then, when the atomized powder was chemically analyzed, the lead content was 25% by weight.

Next, the above-mentioned atomized powder of copper-chromium alloy and atomized powder of copper-lead alloy were mixed so that the proportion of lead was 0.5% by weight, and this mixed powder was mixed with gold having a diameter of 50 mm. After filling in a mold and pressure-molding into a disk shape at a pressure of 3.5 ton / cm ² , this was heated in a vacuum furnace of 5 × 10 ⁻⁵ Torr at 1080 ° C. for 30 minutes and sintered. ..
The results of measuring the content of lead contained in this sintered body for each of the 10 samples are shown in Table 2 as the method of the present invention.
Shown in.

For comparison, a fine powder of copper-chromium alloy obtained by the atomizing method and a powder of lead of 0.5% by weight based on the fine powder of copper-chromium alloy are mixed, and the above-mentioned powder addition method is used. A copper-chromium-lead alloy sintered body was obtained in accordance with the above, and the content of lead contained in this sintered body was measured for each of 10 samples.

Further, a copper powder, a chromium powder, and a lead powder in an amount of 0.5% by weight relative to these are mixed, and the copper, chromium, and lead mixed powder obtained by this is mixed with the above-mentioned conventional method. A copper-chromium-lead alloy sintered body was obtained in accordance with the above, and the results of measuring the lead content in this sintered body for each of the 10 samples are also shown in Table 2.

[0033]

[Table 2]

As is clear from the above results, in the present example in which lead is used as the low melting point metal, the amount of lead scattered is much smaller than that in the powder addition method and the conventional method, and the lead ratio varies. It turned out to be few.

Each of the above-mentioned samples was machined into a spiral electrode having a diameter of 40 mm and incorporated into the vacuum interrupter shown in FIG. 1, and further tested for withstand voltage characteristics and welding resistance. It was also found that the contact resistance value was smaller than that of the conventional method and the variation thereof could be reduced.

Although lead is used as the low melting point metal in the above-described embodiments, another example of the method for manufacturing the electrodes 13 and 14 according to the present invention using tellurium as the low melting point metal will be described below. Atomized powder of copper-chromium alloy is obtained in the same manner as the above method, while
Tellurium (Te) at a ratio of 27% by weight was added to the copper melted by heating at 200 ° C. to obtain a molten mixture of copper and tellurium, which was then sprayed with argon gas at a pressure of 5 to 8 MPa, Atomized powder of copper-tellurium alloy having a particle size of 100 μm or less was obtained. When the atomized powder was chemically analyzed, the tellurium content was 25% by weight.

Next, the above-described atomized powder of copper-chromium alloy and atomized powder of copper-tellurium alloy were mixed so that the ratio of tellurium was 0.5% by weight, and the mixed powder was mixed with gold having a diameter of 50 mm. After filling in a mold and pressure-molding into a disk shape at a pressure of 3.5 ton / cm ² , this was heated in a vacuum furnace of 5 × 10 ⁻⁵ Torr at 1080 ° C. for 30 minutes and sintered. .. Then, Table 3 shows the results of measuring the tellurium content contained in this sintered body for each of the 10 samples as the method of the present invention.

For comparison, copper-chromium alloy fine powder obtained by the atomizing method and 0.5% by weight of tellurium powder with respect to the copper-chromium alloy fine powder are mixed,
A copper-chromium-tellurium alloy sintered body was obtained by the above-mentioned powder addition method, and the content of tellurium contained in this sintered body was 10%.
Table 3 also shows the measurement results of the respective samples.

Further, copper powder, chromium powder and tellurium powder in a proportion of 0.5% by weight with respect to these are mixed,
The mixed powder of copper, chromium and tellurium thus obtained was obtained by the above-mentioned conventional method to obtain a sintered body of a copper-chromium-tellurium alloy, and the content of tellurium contained in this sintered body was measured for each of 10 samples. The results are also shown in Table 3.

[0040]

[Table 3]

As is clear from the above results, even when tellurium is used as the low melting point metal, the method of the present invention has a much smaller amount of tellurium scattered than the powder addition method and the conventional method, and the tellurium ratio varies. Turned out to be less.

Each of the above-mentioned samples was machined into a spiral electrode having a diameter of 40 mm and incorporated into the vacuum interrupter shown in FIG. 1 to further test the withstand voltage characteristics and the welding resistance. It was also found that the contact resistance value was smaller than that of the conventional method and the variation thereof could be reduced.

In the above-mentioned two embodiments, lead and tellurium are individually used as the low melting point metal, but in addition to this, antimony or selenium is independently used, or both of them are used.
Even if more than one kind is mixed, an electrode material having the same performance as the above case can be obtained.

[0044]

According to the method for producing an electrode material of the present invention,
Fine alloy powder of copper and chromium obtained by the atomizing method, and fine alloy powder of copper and low melting point metal obtained by the atomizing method are mixed, and these are heated in a non-oxidizing atmosphere and sintered. As a result, the scattering amount of the low melting point metal is suppressed as compared with the conventional method, and as a result, it becomes possible to control the ratio of the low melting point metal with relatively high accuracy, and the powder addition method or the conventional method is used. As compared with the method, it is possible to provide an electrode material which can have a higher breaking current value, a lower contact resistance value and an excellent welding resistance.

[Brief description of drawings]

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

[Explanation of symbols]

 11,12: Lead bar 13,14: Electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuhisa Suzuki 2-1-1 Osaki, Shinagawa-ku, Tokyo Meiden Shosha Co., Ltd.

Claims (2)

[Claims] 1. A fine alloy powder of copper and chromium obtained by the atomizing method and a fine alloy powder of copper and a metal having a melting point lower than that of copper obtained by the atomizing method are mixed to obtain non-oxidizing properties. A method for producing an electrode material, comprising heating and sintering in an atmosphere. 2. The method for producing an electrode material according to claim 1, wherein the low melting point metal is one or more of bismuth, antimony, tellurium, selenium, and lead.