JPH0474810B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrode material for a vacuum interrupter and a method for manufacturing the same. In general, the electrodes of a vacuum interrupter have the following characteristics: 1. High ability to cut large currents, 2. High insulation strength, 3. Good welding resistance, and 4. Capable of cutting small currents well (severing). It is required that the electrode conditions such as (low current value) be satisfied. Conventionally, various electrode materials have been proposed to satisfy the above electrode conditions. However, the current situation is that none of the electrode materials fully satisfies the above electrode conditions. For example, various electrodes made of copper containing a trace amount of high vapor pressure material (low melting point material), such as
Publication No. 41-12131 (see U.S. Patent No. 3246979)
(hereinafter referred to as Cu-0.5Bi electrode), or as shown in Japanese Patent Publication No. 1983-36071 (see U.S. Patent No. 3596027). What has been done is known. Although electrodes containing these high vapor pressure materials have excellent large current shear breaking capacity, welding resistance, and electrical conductivity, their insulation strength, especially the insulation strength after large current shedding, is extremely low. Moreover, since the cutting current value is as high as 10A, a cutting surge may occur when the current is cut off, so it has the disadvantage that it cannot be cut off easily with small delayed currents. As a result, there was a risk of dielectric breakdown of the electrical equipment on the load side. In addition, for example, as an electrode intended to eliminate the above-mentioned drawbacks of the electrode containing the above-mentioned high vapor pressure material, an electrode made of an alloy of copper and a low vapor pressure material (high melting point material), for example, a special Kosho 54-36121
(see U.S. Patent No. 3,811,939) consisting of 20% by weight copper and 80% by weight tungsten; (see publication)
Those shown in are known. Electrodes containing these low vapor pressure materials have the advantage of increased insulation strength in view of the electrode conditions described above, but they have difficulty in cutting off large currents such as short-circuit currents. There was a drawback. The present invention has been made in view of the above-mentioned technical level, and its purpose is to increase insulation strength while maintaining good welding resistance to an extent that does not cause any disadvantages, and to enable high current and low current An object of the present invention is to provide an electrode material for a vacuum interrupter and a method for manufacturing the same, which can be cut with good quality. To achieve the above object, the present invention relates to a composition and manufacturing method of an electrode material for a vacuum interrupter. The specific invention uses 5 to 40% by weight of iron as the electrode material,
It is composed of a composite metal consisting of 5 to 40% by weight of chromium, 1 to 10% by weight of molybdenum or tungsten, and the remainder copper. In addition, other inventions related to electrode materials include 5 to 40% by weight of iron powder, 5 to 40% by weight of chromium powder,
The composite metal is made of a porous base material in which 1 to 10% by weight of molybdenum or tungsten powder is mutually diffusion-bonded and infiltrated with copper in the remaining weight%. One invention related to the method for manufacturing an electrode material according to the above-mentioned specific invention is to first heat a mixed powder of iron, chromium, and molybdenum or tungsten at a temperature lower than the melting point of iron in a non-oxidizing atmosphere. A porous base material is formed by diffusion bonding the metals to each other, and then a copper material is placed on the base material in a non-oxidizing atmosphere, and the porous base material and copper material are heated above the melting point of iron. This is a method of forming a composite metal by infiltrating a porous base material with a copper material by heating at a low temperature and at a temperature higher than the melting point of copper. In addition, another invention related to the method for manufacturing an electrode material according to the above-mentioned specific invention is that first, a mixed powder of iron, chromium, molybdenum or tungsten and a copper material are placed in a non-oxidizing atmosphere, and then the copper material is placed in a non-oxidizing atmosphere. A porous base material is formed by heating at a temperature lower than the melting point of copper to mutually diffuse bond the metals of the mixed powder, and then heated at a temperature higher than the melting point of copper and lower than the melting point of iron to form a porous base material. This method involves heating the base material and the copper material to infiltrate the copper material into the base material to form a composite metal. Embodiments of the present invention will be described in detail below with reference to figures such as drawings and photographs. FIG. 1 is a longitudinal sectional view of a vacuum interrupter equipped with electrodes according to the present invention. The vacuum interrupter has a plurality of (two in this example) insulating cylinders 1, 1 made of an insulating material such as glass or insulating ceramics molded into a cylindrical shape, and a Fe-Ni- By coaxially joining thin-walled annular sealing fittings 2, 2, etc. made of metal such as Co alloy, an integral insulating cylinder is formed, and both openings of this integral insulating cylinder are Through the other sealing fittings 2, 2, the inside of the container is closed by disc-shaped metal end plates 3, 3 made of stainless steel or the like, and is composed of an integral insulating tube and metal end plates 3, 3. A vacuum container 4 is formed by evacuating to a high vacuum, and a pair of disc-shaped electrodes 5, 5 are inserted into the vacuum container 4 from the center of each metal end plate 3 to maintain the airtightness of the vacuum container 4. At the same time, it is generally configured such that it can be freely contacted and separated (approached and separated) via a pair of electrode rods 6, 6 which are introduced so as to be able to approach and separate relatively. In addition, in FIG. 1, 7 is a metal bellows, 8
is an intermediate potential shield that concentrically surrounds each electrode 5 and the like. Each electrode 5 is made of a composite metal material consisting of 5-40% by weight of iron, 5-40% by weight of chromium, 1-10% by weight of molybdenum or tungsten, and the remainder copper. This electrode material is -100 mesh iron powder 5~40
% by weight, 5 to 40 weight % of -100 mesh chromium powder, and 1 to 10 weight % of -100 mesh molybdenum or tungsten powder are mutually granulated and diffusion bonded to form a porous substrate. The base material has a metal structure in which the remaining weight percent of copper is infiltrated. Hereinafter, a method for manufacturing the above-mentioned electrode material will be explained. First manufacturing method First, the composition ratio is adjusted to be 5 to 40% by weight of iron, 5 to 40% by weight of chromium, and 1 to 10% by weight of molybdenum or tungsten, and the particle size is adjusted to -100 mesh. A predetermined amount of iron powder, chromium powder, and molybdenum or tungsten powder (e.g., equivalent to one electrode including post-processing cutting allowance) is mechanically mixed. The obtained mixed metal powder is then stored in a container with a circular cross section made of a material that does not react with iron, chromium, molybdenum or tungsten, and copper, such as alumina, and the contents are placed in a non-oxidizing atmosphere. (For example, 5×10 ^-5 Torr
Heat and hold at a temperature lower than the melting point of iron (1535℃) (e.g. 600℃) in a vacuum, hydrogen gas, nitrogen gas, or argon gas at the following pressures:
~1000°C for about 5 to 60 minutes), thereby diffusion bonding the iron powder, chromium powder, and molybdenum or tungsten powder to each other to produce a porous base material. Next, in the same or different non-oxidizing atmosphere as in the above diffusion bonding step, a copper material such as a copper block or copper powder is placed on the porous base material, and the porous base material and the copper material are bonded together. Above the melting point (1083℃),
5 to 20 at a temperature lower than the melting point of iron (1535℃)
The porous base material is infiltrated with the molten copper material by heating and holding for about a minute. This produces a composite metal material consisting of iron, chromium, molybdenum or tungsten, and copper. The first manufacturing method described above is characterized in that the step of forming a porous base material (diffusion bonding) and the step of infiltrating the copper material into this porous base material are completely separated. No copper material is placed in this container when the porous base material is formed by diffusion bonding inside the container. Therefore, in the first manufacturing method, the porous base material is formed in a gas such as hydrogen gas, nitrogen gas, or argon gas, and the copper material is infiltrated into the porous base material under vacuum. It can also be done. In addition, a porous columnar base material equivalent to many electrodes is manufactured in various non-oxidizing atmospheres, and this porous columnar base material is cut into the required thickness and shape to form, for example, one electrode. After the porous base material is processed into a porous base material, the copper material may be infiltrated into the porous base material under vacuum. Second manufacturing method In the second manufacturing method, a mixed powder of iron powder, chromium powder, molybdenum powder or tungsten powder, and a copper material are placed in the same container, and the diffusion bonding process of the mixed powder and the copper material are carried out. The feature is that the material infiltration process is performed consistently by changing the heating temperature in the same non-oxidizing atmosphere. That is, in the second manufacturing method, first,
The composition ratio is adjusted to be 5-40% by weight of iron, 5-40% by weight of chromium, and 1-10% by weight of molybdenum or tungsten, and the particle size is -100%.
Predetermined amounts of meshed iron powder, chromium powder, and molybdenum or tungsten powder are mechanically mixed. Next, the obtained metal mixed powder is stored in a container with a circular cross section made of a material that does not react with iron, chromium, molybdenum or tungsten, and copper, such as alumina, and a copper material is placed on the metal mixed powder. place Next, the contents in the container are heated and held at a temperature lower than the melting point of copper (for example, heated at 600 to 1000°C for ⁵⁰ minutes) in a non-oxidizing atmosphere (for example, in a vacuum at a pressure of 5 × 10 -5 Torr or less). (about 60 minutes), thereby diffusion bonding the iron powder, chromium powder, and molybdenum or tungsten powder to each other.
Produce a porous substrate. Next, the obtained porous base material and copper material were heated at a temperature higher than the melting point of copper (1083°C) and at the melting point of iron (1535°C).
The porous substrate is heated and maintained at a lower temperature (for example, 1100° C.) for about 5 to 20 minutes to infiltrate the molten copper material into the porous base material. This produces a composite metal material consisting of iron, chromium, molybdenum or tungsten, and copper. Incidentally, in both the first and second methods, a vacuum is preferable as a non-oxidizing atmosphere since it has the advantage that degassing can be performed simultaneously during heating and holding. Of course, even if it is manufactured in a gas other than vacuum, there is no problem in practical use as an electrode for a vacuum interrupter. The reason why the diameter of each metal particle in each of the metal powders is set to -100 mesh is to ensure that each metal particle is uniformly dispersed in the metal structure of the electrode material and that mutual diffusion bonding is good. In addition, the heating temperature and time required for interdiffusion bonding of metal powders should be determined by considering the furnace conditions, the shape and size of the porous substrate to be formed, workability, etc., and the desired electrode material. It is heated and maintained at 600℃ for example.
The work is carried out under heating conditions such as 60 minutes or 5 minutes at 1000°C. Next, the metal structure according to the example of the electrode material manufactured by the above-mentioned second manufacturing method (the non-oxidizing atmosphere was in a vacuum of 5 × 10 ^-5 Torr) was
Figures A, B, C, D and E and Figure 3 A,
Shown in B, C, D and E. Figure 2 A, B, C, D and E are Example-1
The electrode material contains 23% by weight of iron, 22% by weight of chromium, 5% by weight of molybdenum, and 5% by weight of copper.
This is a characteristic photograph taken by an X-ray microanalyzer of an electrode material having a composition ratio of 50% by weight. FIG. 2A is a characteristic photograph showing a secondary electron image, and FIG. 2B is a characteristic X-ray image of dispersed iron (Fe), in which the island-like white portions are iron. Second
Figure C is a characteristic X-ray image of dispersed chromium Cr, where the scattered white parts are chromium. FIG. 2D is a characteristic X-ray image of dispersed molybdenum Mo, where the scattered white parts are molybdenum. Figure 2E is a characteristic X-ray image of infiltrated copper, with the white portion being copper. As can be seen from this figure 2, iron Fe, chromium Cr,
Each molybdenum Mo powder (powder) is mutually diffusion-bonded to form a porous base material. It can be seen that by infiltrating the pores (gap) of this porous base material with copper, a composite metal with a strong bond is formed as a whole. In addition, in B to E of FIG. 2, each white part indicates an element, and a part with many white parts (white dots) indicates that the concentration of that element is high. (The same applies to Fig. 3, which will be described later.) Fig. 3 A, B, C, D, and E show Example-2.
The electrode material contains 23% by weight of iron, 22% by weight of chromium, 5% by weight of tungsten, and 5% by weight of copper.
This is a characteristic photograph taken by an X-ray microanalyzer of an electrode material having a composition ratio of 50% by weight. FIG. 3A is a characteristic photograph showing a secondary electron image, and FIGS. 3B, C, and E are similar to those in FIG. 2B, C, and E.
Chromium Cr and copper Cu are shown respectively. Therefore, Fig. 3D shows the dispersed tungsten W.
In the characteristic X-ray image, the scattered white parts are tungsten. As can be seen from this figure 3, iron Fe, chromium Cr,
The tungsten W powders are mutually diffusion-bonded to form a porous base material. It can be seen that by infiltrating the pores (gap) of this porous base material with copper, a composite metal with a strong bond is formed as a whole. The electrode materials of Example-1 and Example-2 having the metal structures illustrated and detailed above were prepared with a diameter of 50 mm.
The electrodes are formed into a circular plate with a thickness of 6.5 mm and a rounded edge of R = 4 mm, and these electrodes are assembled into a pair of vacuum interrupters having the configuration shown in Figure 1. Various performances were verified. The verification results were as follows. In addition, when the electrode made of the electrode material containing tungsten shown in FIG. 3 of Example-2 has different performance from the electrode made of the electrode material containing molybdenum of Example-1 shown in FIG. Special mention will be made each time. 1 Electrical conductivity of electrode material (IACS) In the case of Example-1, it was 3 to 20%, and in the case of Example-2, it was 2 to 30%. 2 Welding resistance After pressurizing both electrodes 5, 5 with a force of 130 Kgf and passing a current of 25 kArms between these electrodes 5, 5 for 3 seconds (IEC short-time current standard), both electrodes 5,
5 can be pulled off without any problem with a static tripping force of 200Kgf, and the subsequent increase in contact resistance is 2~
It remained at 8%. In addition, both electrodes 5 and 5 are pressurized with a force of 1000 Kgf, and a current of 50 kArms is applied between these electrodes 5 and 5.
After being energized for a second, both electrodes 5, 5 could be pulled off without any problem with a static tripping force of 200 Kgf, and the subsequent increase in contact resistance remained at 2-7%. Therefore, the welding resistance was maintained well to the extent that it was not inconvenient for practical use. 3. Cutting current value When a test current of 30 A was applied, the mean cutting current value was 3.8 A (standard deviation σn = 1.8, number of samples n = 100). Further, in the case of the electrode material containing tungsten of Example-2, the average cutting current value was 3.8 A (standard deviation σn = 1.3, n = 100). 4. Large current cutting ability: It was able to cut a current of 12kArms. 5 Insulation strength When the gap between poles was maintained at 3.0 mm and an impulse withstand voltage test was performed, the result was ±120 kV (variation ±
It showed a withstand voltage value of 10kV). 6. Insulation strength after insulation failure An impulse withstand voltage test was conducted by applying a current of 12kA several times and maintaining a gap of 3.0mm after failure, and it showed a withstand voltage value of ±110kV (variation 10kV). 7 Insulation strength after small current switching A small current continuous switching test was conducted 10,000 times at a current of 80A. The withstand voltage value is between the initial period and 10,000 times.
There was almost no change. 8. Leading small current shielding ability The leading small current shielding test (JEC181) with voltage 84×1.25/√3kV and current 80A was conducted 10,000 times. No restrike occurred in both electrodes 5,5. Next, in the electrode material having the composition according to the present invention,
The severing current value (average value when 30A current is applied) and impulse withstand voltage value when changing the composition ratio of iron, chromium, molybdenum, and copper or the composition ratio of iron, chromium, tungsten, and copper are calculated as follows: Shown in Table and Table 2. Composition ratio of Fe, Cr, W and Cu

【table】 Composition ratios of Fe, Cr, Mo and Cu

[Table] As can be seen from items 1) to 8) above, the vacuum interrupter having the electrode made of the electrode material of the present invention has excellent performance, and the vacuum interrupter having the electrode made of the electrode material of the present invention has excellent performance. A comparison of the various performances of a vacuum interrupter with a −0.5Bi electrode revealed the following. a Large current breaking capacity Both are the same. b. Insulating Strength The impulse withstand voltage value exhibited by the pair of Cu-0.5Bi electrodes at an electrode gap of 10 mm was the same as the impulse withstand voltage value exhibited by the pair of electrodes according to the present invention at an electrode gap of 3.0 mm. Therefore, the electrode according to the present invention has three types of Cu-0.5Bi electrodes.
It has twice the insulation strength. c Welding resistance The welding resistance of the electrode according to the present invention is Cu-0.5Bi
70% of the electrode's welding resistance. However, there is almost no problem in practical use, and if necessary, the tripping force at the instant of electrode separation may be slightly increased. d Leading Small Current Breaking Capacity The electrode according to the present invention can cut twice as much capacitance load as the Cu-0.5Bi electrode. e Cutting current value The cutting current value of the electrode according to the present invention is Cu-
The cutting current value was 30% smaller than that of the 0.5Bi electrode. In addition, electrodes with compositions other than those shown in Tables 1 and 2 have also been compared with Cu-0.5Bi electrodes.
It exhibited almost the same performance as the compositions of Example-1 and Example-2 described above. However, when the iron content was less than 5% by weight, the cutting current value suddenly increased, and on the other hand, when the iron content exceeded 40% by weight, the large current cutting ability suddenly decreased. Furthermore, when the content of chromium was less than 5% by weight, the cutting current value suddenly increased, while when it exceeded 40% by weight, the ability to cut large currents suddenly decreased. In addition, if molybdenum or tungsten is less than 1% by weight, the insulation strength will decrease rapidly.
On the other hand, when the content exceeded 10% by weight, the ability to withstand large currents suddenly decreased. Furthermore, if the copper content is less than 10% by weight, the contact resistance after energization increases rapidly, as seen from the short-time current test results, and in other words, the conductivity of the electrode decreases rapidly. During this period, the Joule heat increased rapidly, reducing the practicality of electrodes containing less than 10% copper. On the other hand, when the copper content exceeded 89%, the insulation strength and welding resistance rapidly decreased. As mentioned above, the specified invention provides a vacuum cleaner made of a composite metal of 5 to 40% by weight of iron, 5 to 40% by weight of chromium, 1 to 10% by weight of molybdenum or tungsten, and the remainder copper. Since this electrode is an interrupter electrode, it dramatically increases the insulation strength of the vacuum interrupter compared to conventional electrodes containing high vapor pressure materials such as Cu-0.5Bi electrodes, and The cutting current value can be dramatically reduced. Furthermore, compared to conventional electrodes containing low vapor pressure materials such as 20Cu-80W, large currents can be cut and interrupted more effectively. Therefore, the electrode material according to the specific invention can effectively perform large current shedding, leading small current shedding, and delayed small current shedding. In addition, 5 to 40% by weight of iron powder, 5 to 40% by weight of chromium powder, and 1 to 10% by weight of electrode material.
This electrode material for vacuum interrupters is made by infiltrating a porous base material in which molybdenum or tungsten powder is mutually diffusion-bonded and infiltrated with the remaining weight percent of copper material.In addition to the various effects mentioned above, the electrode material Mechanical strength can be improved. In addition, one invention related to the manufacturing method of an electrode material according to the specified invention is that a mixed powder of iron, chromium, and molybdenum or tungsten is held in a non-oxidizing atmosphere at a predetermined temperature for a predetermined period of time to form a diffusion bond with each other. The electrode material is manufactured by placing the copper material on the porous base material and infiltrating the copper material into the porous base material in a non-oxidizing atmosphere. Good bonding can be achieved between the electrode materials, the dispersion state can be made uniform, and the electrical and mechanical properties of the electrode material can be made excellent. In addition, another invention related to the manufacturing method of an electrode material according to the specified invention is that a mixed powder of iron, chromium, molybdenum or tungsten and a copper material are placed together in a predetermined container, and then the same non-oxidizing Since the interdiffusion bonding of the mixed powder and the infiltration of the copper material are performed consistently in an atmosphere by simply controlling the temperature, in addition to the effects associated with the invention 1 above, there is also the effect of omitting part of the work process. play.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a vacuum interrupter having electrodes made of the electrode material according to the present invention, and FIG.
Figures A, B, C, D and E show electrode materials made of composite metals with a composition of 23% by weight iron, 22% by weight chromium, 5% by weight molybdenum and 50% by weight copper.
Characteristic photographs taken with a line microanalyzer, Figure 2A shows a secondary electron image of the electrode material, Figure 2B,
C, D and E show characteristic X-ray images of iron, chromium, molybdenum and infiltrated copper in a dispersed state. Figures A, B, C, D, and E are characteristic photographs taken by an X-ray microanalyzer of an electrode material having a composition of 23% by weight of iron, 22% by weight of chromium, 5% by weight of tungsten, and 50% by weight of copper. Figure 3A is
Secondary electron images of the electrode material are shown in Figure 3 B, C, and D.
and E shows characteristic X-ray images of iron, chromium, tungsten and infiltrated copper in a dispersed state.

Claims (1)

[Claims] 1. Electrode material for a vacuum interrupter made of a composite metal of 5 to 40% by weight of iron, 5 to 40% by weight of chromium, 1 to 10% by weight of molybdenum or tungsten, and the remainder copper. . 2 The remaining weight percent of copper is melted into a porous base material in which 5 to 40 weight percent of iron powder, 5 to 40 weight percent of chromium powder, and 1 to 10 weight percent of molybdenum or tungsten powder are mutually diffusion-bonded. Vacuum interrupter electrode material made of immersed composite metal. 3. First, in a non-oxidizing atmosphere, a mixed powder of iron, chromium, and molybdenum or tungsten is heated at a temperature lower than the melting point of iron to diffusely bond the metals in the mixed powder to each other, thereby creating a porous structure. Next, a copper material is placed on the porous base material in a non-oxidizing atmosphere, and the porous base material and the copper material are heated at a temperature lower than the melting point of iron and at a temperature lower than the melting point of copper. A method for producing an electrode material for a vacuum interrupter by heating at a temperature above to infiltrate a porous base material with a copper material to make a composite metal. 4. First, a mixed powder of iron, chromium, and molybdenum or tungsten and a copper material are placed together in a non-oxidizing atmosphere, and then heated at a temperature lower than the melting point of copper to separate each metal in the mixed powder. A porous base material is formed by diffusion bonding them to each other, and then the porous base material and the copper material are heated at a temperature higher than the melting point of copper and lower than the melting point of iron to make the copper material porous. A method for manufacturing an electrode material for a vacuum interrupter made into a composite metal by infiltrating it into a base material.