JPH02117040A - Electrode material for vacuum interrupter - Google Patents

Abstract

PURPOSE:To contrive to improve characteristics such as fusion resistance, current breaking property and current chopping values by making an electrode consist of specified quantities of copper, chromium carbonate, nickel, cobalt, iron and bismuth respectively. CONSTITUTION:Each electrode 13 and 14 is composed of copper ranging from 20 to 70% by weight, chromium carbonate ranging from 5 to 75% by weight, nickel ranging from 0.1 to 10% by weight, cobalt ranging from 0.1 to 10% by weight, iron ranging from 0.1 to 10% by weight and of bismuth ranging from 1 to 20% by weight. In this case, each powder of chromium carbonate, nickel, cobalt and iron is mixed uniformly so as to be heated at temperature below the melting points of chromium carbonate, nickel, cobalt and iron so that a sintered porous body is obtained, and furthermore copper and bismuth are dissolved into the porous section of the sintered body. This constitution improves characteristics such as fusion resistance, current breaking property and current chopping values.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrode material for a vacuum interrupter made of an inexpensive infiltrated composite metal with improved characteristics such as current interrupting performance and current interrupting value.

B. Summary of the Invention This is an electrode material for a vacuum interrupter made of copper, chromium carbide, nickel, cobalt, iron, and bismuth, which has improved properties such as weldability, current cutting performance, and current cutting value. .

C. Conventional technology In general, the main performances required for electrode materials for vacuum interrupters are: (1) good adhesion resistance, (2) high current cut-off performance, and (3) low current cut-off value. etc. can be mentioned.

However, since increasing the current cutting performance and lowering the current cutting value of an electrode material are due to mutually contradictory physical properties, it is impossible to satisfy all of the above characteristics with a single electrode material. Currently, it is difficult to select the electrode material that best suits the type of vacuum incretor.

For example, the steel-bismuth alloy disclosed in Japanese Patent Publication No. 41-12131, etc. is! (Cu) with 0.5% by weight of bismuth (Bi), which has a high vapor pressure and a low melting point,
It is well known that it has good welding resistance and current interrupting performance. In addition, the sintered tungsten steel metal disclosed in Japanese Patent Publication No. 54-36121 Kokai et al. is made by adding 20% by weight of steel to tungsten (W), which has a low vapor pressure and a high melting point, and has a high current breaking value. has a low advantage. As an electrode material with a particularly low current cutoff value, Utility Model Application No. 55-121
Tungsten carbide silver sintered metal disclosed in Publication No. 429 etc., that is, tungsten carbide (WC)* (Ag)
There are those containing 830% by weight.

D. Problems to be Solved by the Invention Although copper-bismuth alloys have good current cutting performance, they have a high current cutting value of, for example, IOA, and may generate cutting surges when cutting current. For this reason, it is difficult to cut off the delayed small current in a good manner, which may cause dielectric breakdown of the electrical equipment on the load side.

Furthermore, although tungsten copper sintered metal and tungsten silver carbide sintered metal have a low current cutting value, they have poor current cutting performance and cannot cut off a large current as large as the short circuit current.

Furthermore, since tungsten silver carbide sintered metal contains a relatively large amount of silver, it is expensive as an electrode material, which becomes an obstacle in reducing the manufacturing cost of vacuum incluctors.

E. Means for Solving the Problems The electrode material of the vacuum interrupter according to the present invention contains steel in a range of 20 to 70% by weight in order to improve properties such as welding resistance, current interrupting performance, and current interrupting value. 5 to 75
chromium carbide in the range of M%, nickel in the range of 0.1 to 10% by weight, cobalt in the range of 0.1 to 10% by weight, iron in the range of 0.1 to 10% by weight, 1 From 2
bismuth in the range of 0% by weight.

In this case, chromium carbide, nickel, cobalt, and iron powders are uniformly mixed and heated at a temperature below the melting point of nickel (and chromium carbide, cobalt, and iron) to obtain a porous sintered body. Furthermore, copper and bismuth are infiltrated into the voids of this sintered body to obtain the fIiffi material of the present invention. Note that these sintering and infiltration steps are desirably performed in a non-oxidizing atmosphere while degassing.

If the copper content is less than 20% by weight, the electrical conductivity will decrease and the amount of heat generated will increase, while if the copper content exceeds 70% by weight, the welding resistance will decrease and the current cutoff value will increase. bring. If the chromium carbide content is less than 5% by weight or if the bismuth content is less than 1% by weight, the current cutoff value will increase. Furthermore, if chromium carbide exceeds 75% by weight, or if each of nickel, cobalt, or iron exceeds 10% by weight, each of them will react with copper, resulting in a decrease in electrical conductivity. Conversely, nickel, cobalt, and iron each have a concentration of 0.1
If it is less than % by weight, the hardening phenomenon due to the influence of chromium carbide will not be inhibited and hardening will not occur, resulting in a decrease in machinability. On the other hand, if bismuth exceeds 20% by weight, the durability as an electrode and a vacuum interrupter decreases rapidly.

Since we have found a suitable Ik composition of copper, chromium carbide, nickel, cobalt, iron, and bismuth, we can meet the overall requirements for vacuum incretors in terms of welding resistance, dielectric strength, current interrupting performance, and current interrupting value. It is possible to obtain electrode materials with improved properties.

Embodiment G The vacuum interrupter is as shown in FIG. 2, which shows an example of its schematic structure.
13 p 14 are integrally provided. These electric 313
．． A central portion of the outer periphery of a cylindrical shield 15 surrounding the shield 14 is held between a pair of insulating cylinders 16 and 17 surrounding the shield 15.

One of the lead rods 11 is integrally fixed to the metal end plate 18 joined to one end of the insulating tube 16 while airtightly passing through the metal end plate 18 . The other lead rod 12, which is connected to a drive device (not shown), is connected via a bellows 20 to the other metal end plate 19, which is hermetically joined to the other end of the other insulating tube 17. The movable electrode 14 is configured to open and close with respect to the fixed electrode 13 so that the electrodes 13 and 140 can reciprocate in opposing directions.

The electrodes 1ii13,14 contain copper (Cu) in the range of 20 to 70% by weight, chromium carbide (e.g. Cr5C2) in the range of 5 to 75% by weight, and nickel (N) in the range of 0.1 to 10% by weight. i ), cobalt (Co) ranging from 0.1 to 10% by weight, iron (Fe) ranging from 0.1 to 10% by weight, and bismuth (ranging from 1 to 20% by weight).
It is composed of a composite metal consisting of Bi).

An example of the manufacturing method of this electrode material is described below.
00 mesh particle size of chromium carbide, nickel, cobalt, and iron powders are mechanically mixed, and a predetermined amount of this mixed powder is charged into an alumina ceramic container, and a lump of copper-bismuth alloy is placed on top of the mixed powder. The lid is placed on the container while it is placed, and the container is heated in a vacuum furnace while being degassed. First, the chromium carbide particles, nickel particles, cobalt particles, and iron particles are diffused and bonded to each other, forming a porous molten metal. Obtain the soaked base material. Thereafter, copper and bismuth are infiltrated into the voids of the infiltrated base material, but at this time, the inside of the container becomes an atmosphere containing a large amount of bismuth vapor. Then, the obtained electrode material is taken out of the container and machined into a predetermined size and shape.

In this way, an electrode material consisting of CrC: 40% by weight, Ni: 1% by weight, Co: 3% by weight, Fs: 1% by weight, Bi: 15% by weight, Cu: the remainder was created as a first sample, and other than this first sample CrC: 35% by weight Ni: 5% by weight Co: 2% by weight Fe: 4% by weight Bi: 12% by weight Cu: The second sample consisting of the remainder and CrC: 45% by weight Ni: 1% by weight Co: 5 Weight% Fe: 1% by weight Bi: 10% Cu: A third sample consisting of the remainder was prepared and processed into a disc shape with a diameter of 50mm and a thickness of 6.5mm, and 4mm marks were placed on the outer periphery. A material with a rounded radius of curvature was incorporated as the electrodes 13 and 14 of a vacuum interrupter shown in FIG. 2, and the welding resistance, current interrupting performance, and current interrupting value were examined.

Regarding the welding resistance, the movable side electrode 13 is pressurized against the fixed side electrode 14 at 130 kgf, and in this state 25 kgf is applied.
After applying a current of kA (r, us, ) for 3 seconds,
When a static tensile force of 200 kgf was applied to the electrode 8ii1-3, the electrode 13 could not be separated from the electrode 14 without any problem in all three samples. Further, the subsequent increase in contact resistance was within 20%7 for all three samples.

Regarding current cutting performance, the first sample was able to cut off a current of 19 kA (r, ms,) under a voltage condition of 7.2 kV, and the second sample was able to cut off a current of 21 kA (r, ms,). The third sample was able to cut off a current of 23 kA (gate 1.).

On the other hand, the current cutoff value is 200V.

After opening and closing the vacuum interrupter/load at 120A 100 times,
As a result of determining the current cutoff value after 1,000 cycles, -10,000 cycles, and 100,000 cycles, good results were obtained that remained below IA even after 100,000 cycles, as shown in Fig. 1. In addition, O shown in this Figure 1
mark.

The Δ and x marks each represent the average value of 50 measurements, ω is the first sample, Sa and Buddha is the second sample, X----X
shows the transition of each current cutoff value of the third sample.

It has a lower current cutoff value than conventional copper-bismuth alloys, and has higher current cutoff performance than sintered tungsten copper metal or sintered tungsten silver carbide metal, and has excellent welding resistance, current cutoff performance, and current cutoff value. An electrode material with overall improved properties can be obtained. Specifically, it is possible to provide a vacuum interrupter that can maintain a current cutoff value at a low value of IA or less even after opening and closing 100,000 times. Furthermore, since no expensive silver is used, the cost of the electrode material itself can be reduced.

According to the electrode material of the vacuum interrupter of the present invention, copper in the range of 20 to 70% by weight, chromium carbide in the range of 5 to 75% by weight, and nickel in the range of 0.1 to 10% by weight. , cobalt in the range of 0.1 to 10% by weight, and 0.1
It is composed of iron in the range of 1 to 10% by weight and bismuth in the range of 1 to 20% by weight.

[Brief explanation of drawings]

FIG. 1 is a graph showing the characteristics of the current cutoff value when the present invention is applied to a vacuum interrupter, and FIG. 2 is a sectional view showing an example of the vacuum interrupter. In the figure, 11 and 12 are lead rods, and 13 and 14 are electrodes. Figure 2: Cross-sectional view of the vacuum interrupter Figure 1: Graph showing the current cut-off value of this example The number of load switching times (times)

Claims (1)

[Claims] copper in the range of 20 to 70% by weight, chromium carbide in the range of 5 to 75% by weight, nickel in the range of 0.1 to 10% by weight, and cobalt in the range of 0.1 to 10% by weight;
Iron in the range 0.1 to 10% by weight and 1 to 20% by weight
Vacuum interrupter electrode material consisting of bismuth and in the range of.