JP6253494B2 - Contact material for vacuum valve and vacuum valve - Google Patents

Description

  The present invention relates to a contact material for a vacuum valve and a vacuum valve used for a vacuum circuit breaker and the like.

  With the increase in capacity, pressure resistance and miniaturization of vacuum circuit breakers, there has been a demand for improved performance of vacuum valves mounted on vacuum circuit breakers. A vacuum valve has a structure in which a fixed electrode and a movable electrode are coaxially arranged in an insulating container maintained at a high vacuum. When an overload current or a short-circuit current is generated, these electrodes are The current is cut off by opening the electrode instantaneously. The contact material used for the contact portion of the fixed electrode and the movable electrode of such a vacuum valve is mainly required to have a breaking performance, a withstand voltage performance, and a welding resistance performance. Since these performances required for the contact material have mutually opposite properties, it is difficult to manufacture the contact material using a material composed of a single element. Therefore, the conventional contact material is manufactured using the material which combined 2 or more types of elements.

  In general, a Cu—Cr alloy is known as a contact material excellent in breaking performance and withstand voltage performance. Further, as a contact material having further improved withstand voltage performance, an alloy containing Cu, Cr, and auxiliary components such as Fe, Co, Nb, Ta, Mo, and W has been proposed (for example, Patent Documents). 1).

JP 2004-192992 A

  However, since conventional contact materials such as Patent Document 1 have insufficient surface hardness, they have advanced small current interruption performance (capacity small current interruption performance such as charging current of no-load transmission line and load current of capacitor) There is a problem that is not enough. That is, in the conventional contact material, the contact surface unevenness is increased because the welding trace is extended when the contact welding is peeled off at the small current interruption. As a result, there is a problem that electric field concentration occurs at the tip of the welding mark and the withstand voltage performance is lowered.

  The present invention has been made in order to solve the above-described problems, and is a vacuum valve contact material excellent in advanced small current interruption performance, and a vacuum having a contact made of a vacuum valve contact material having the characteristics. The object is to provide a valve.

  As a result of diligent research to solve the above problems, the inventors of the present invention have developed a contact layer having a particle size of 1 μm or less, in which Cr fine particles and specific intermetallic compound fine particles are dispersed in a Cu base material. It was found that the surface hardness of the contact material can be increased, and the extension of the welding marks when peeling the contact weld can be suppressed.

That is, the present invention is a base material in which at least one metal particle selected from Cr particles and Nb particles and Ta particles is dispersed in a Cu base material, and a contact layer formed on the base material, A contact layer in which Cr fine particles having a particle size of 1 μm or less, and at least one intermetallic compound fine particle having a particle size of 1 μm or less and selected from Cr ₂ Nb fine particles and Cr ₂ Ta fine particles are dispersed in a Cu base material; It is a contact material for vacuum valves characterized by having.
Moreover, this invention is a vacuum valve characterized by having the contact which consists of said contact material for vacuum valves.

  ADVANTAGE OF THE INVENTION According to this invention, the vacuum valve which has the contact which consists of the contact material for vacuum valves excellent in advance small current interruption | blocking performance, and the contact material for vacuum valves which has the said characteristic can be provided.

3 is a schematic cross-sectional view of a contact material according to Embodiment 1. FIG. 6 is a schematic cross-sectional view of a vacuum valve according to Embodiment 2. FIG.

  Hereinafter, preferred embodiments of the contact material for a vacuum valve and the vacuum valve of the present invention will be described.

Embodiment 1 FIG.
FIG. 1 is a schematic cross-sectional view of a vacuum valve contact material (hereinafter abbreviated as “contact material”) according to the present embodiment.
As shown in FIG. 1, the contact material 1 includes a base material 2 and a contact layer 3 formed on the base material 2. The base material 2 has a structure in which Cr particles 4 and metal particles 5 are dispersed in a Cu base material 6. The contact layer 3 has a structure in which Cr fine particles 7 and intermetallic compound fine particles 8 are dispersed in a Cu base material 6. The base material 2 and the contact layer 3 may contain a small amount of inevitable impurities (Ag, Al, Fe, Si, P, etc.) contained in the raw material.

The Cr particles 4 and the metal particles 5 in the base material 2 are components that give the contact material 1 withstand voltage performance.
As the metal particles 5, Nb particles, Ta particles, or a combination thereof is used. By using such metal particles 5, the withstand voltage performance is improved, and at the same time, the base material 2 can be surface-treated to form the hard contact layer 3 having a specific structure on the base material 2. .

  The contents of the Cr particles 4, the metal particles 5, and the Cu base material 6 in the base material 2 may be appropriately set according to required characteristics, and are not particularly limited. From the viewpoint of achieving both withstand voltage performance and interrupting performance, the content of the Cr particles 4 is preferably 15 mass% to 55 mass%, more preferably 20 to 50 mass%, and the content of the metal particles 5 is The content of the Cu base material 6 is preferably 25 to 84% by mass, more preferably 35 to 77% by mass, preferably 1 to 20% by mass, more preferably 3 to 15% by mass.

  The particle diameters of the Cr particles 4 and the metal particles 5 are not particularly limited, but are preferably more than 1 μm and 100 μm or less, and more preferably 10 μm to 80 μm. Here, “the particle size of the Cr particles 4 and the metal particles 5” in this specification means a particle size determined through a sieve having a predetermined open space diameter.

A method for producing the base material 2 is not particularly limited, and methods known in the technical field such as an infiltration method, a powder metallurgy method, and a casting method can be used. The base material 2 may be produced by subjecting the raw material powder to spark plasma sintering and then heat treatment. The base material 2 is preferably machined to have a desired contact shape.
For example, when using the infiltration method, Cr powder composed of Cr particles 4, metal powder composed of metal particles 5, and optionally Cu powder as a binder are mixed, molded and sintered to obtain a porous sintered body. Then, Cu can be infiltrated into the porous sintered body.

Although it does not specifically limit as a shaping | molding method of powder, For example, powder may be filled in the metal mold | die of a press molding machine, and what is necessary is just to press-mold with a predetermined pressure. Although it does not specifically limit as a pressure at the time of pressure molding, Preferably it is 100 Mpa or more and 150 Mpa or less.
Although it does not specifically limit as a sintering method after shaping | molding, What is necessary is just to heat a molded object to the sintering temperature of 1100 degreeC or more and 1200 degrees C or less in non-oxidizing atmospheres, such as a vacuum or hydrogen atmosphere. When the sintering temperature is less than 1100 ° C., the sintering becomes insufficient and the contact material 1 may become brittle. On the other hand, if the sintering temperature exceeds 1200 ° C., the powder (particularly Cu powder) may melt and the shape maintainability may deteriorate. Further, the sintering time may be appropriately adjusted according to the size of the contact material 1 to be produced, and is not particularly limited.

  Cu infiltration is performed by heating to a melting point of Cu (1083 ° C.) or higher in a reducing gas atmosphere such as hydrogen gas. Here, when heating temperature exceeds 1200 degreeC, the surface tension of molten Cu will become low and infiltration property may fall. Therefore, it is preferable that the heating temperature is set to the melting point of Cu or higher and 1200 ° C. or lower. The infiltration time is not particularly limited as long as it is sufficient for the molten Cu to permeate the entire pores in the porous sintered body, but is generally 2 hours or more and 3 hours or less.

The contact layer 3 is a layer that becomes a part where the contacts come into contact with each other by opening and closing the vacuum valve when the contact made of the contact material 1 is arranged in the vacuum valve. In general, if the surface of the contact layer 3 is not sufficiently hard, the contact marks are extended when the contact is peeled off in the advanced small current interruption, so that the surface unevenness of the contact becomes large. As a result, electric field concentration occurs at the tip of the welding mark, and the withstand voltage performance decreases.
On the other hand, the contact layer 3 formed on the contact material 1 of the present embodiment has a structure in which Cr fine particles 7 and intermetallic fine particles 8 are dispersed in the Cu base material 6. The surface is harder than the material 2. That is, the contact layer 3 has a harder surface than the base material 2 because the Cr fine particles 7 and the intermetallic compound fine particles 8 that are harder than the Cu base material 6 are finely dispersed in the soft Cu base material 6. In the case of the contact material 1 having the contact layer 3 having such a hard surface, it is possible to suppress the extension of the welding marks when the contact welding is peeled off and to prevent the withstand voltage performance from being lowered in the progress small current interruption. Can do.

The Cr fine particles 7 in the contact layer 3 are components that impart voltage resistance performance to the contact material 1. Further, the intermetallic compound fine particles 8 in the contact layer 3 are components that give the contact material 1 withstand voltage performance and increase the hardness of the contact layer 3.
As the intermetallic compound fine particles 8, Cr ₂ Nb fine particles, Cr ₂ Ta fine particles, or a combination thereof is used. By using such intermetallic compound fine particles 8, it is possible to suppress the extension of the welding marks when peeling off the welding of the contacts, and to prevent the withstand voltage performance from being lowered.

  The contents of the Cr fine particles 7, the intermetallic compound fine particles 8, and the Cu base material 6 in the contact layer 3 may be set as appropriate according to the required characteristics, and are not particularly limited. From the viewpoint of improving both the withstand voltage performance and the breaking performance, and at the same time improving the small current breaking performance, the content of the Cr fine particles 7 is preferably 15 to 55 mass%, more preferably 20 to 50 mass%. Yes, the content of the intermetallic compound fine particles 8 is preferably 1 to 20% by mass, more preferably 3 to 15% by mass, and the content of the Cu base material 6 is preferably 25 to 84% by mass, more preferably Is 35-77 mass%.

  The particle diameters of the Cr fine particles 7 and the intermetallic compound fine particles 8 are 1 μm or less, preferably 10 nm or more and 1 μm or less from the viewpoint of obtaining desired hardness and advanced small current interruption performance. Here, in the present specification, the “particle diameter of the Cr fine particles 7 and the intermetallic compound fine particles 8” means the particle diameters of the Cr fine particles 7 and the intermetallic compound fine particles 8 measured in an electron micrograph, particularly SEM. To do. When the particle diameters of the Cr fine particles 7 and the intermetallic compound fine particles 8 exceed 1 μm, the hardness of the contact layer 3 is not sufficient, and the advanced small current interruption performance is deteriorated.

  The thickness of the contact layer 3 is not particularly limited, but is preferably 100 μm or less, more preferably 10 μm or more and 100 μm or less. When the thickness of the contact layer 3 exceeds 100 μm, the particle diameter of the intermetallic compound fine particles 8 tends to increase, and it may not be possible to suppress a decrease in desired hardness and advanced small current interruption performance.

The contact layer 3 can be formed by arc melting the surface of the base material 2. For example, the surface of the base material 2 is exposed to an arc, and the components (Cr particles 4, metal particles 5 and Cu base material 6) of the base material 2 are melted and then rapidly solidified. The arc melting is preferably performed in an inert gas atmosphere such as argon, helium, and nitrogen from the viewpoint of preventing the gas from entering the contact layer 3. The structure of the surface of the base material 2 is refined by arc melting, and the Cr fine particles 7 and the intermetallic compound fine particles 8 are dispersed in the Cu base material 6.
In addition, since the conditions at the time of arc melting depend on the kind of arc melting apparatus to be used etc., it is necessary to set suitably according to the kind of arc melting apparatus to be used.

Arc melting can also be performed by placing the base material 2 in a vacuum valve and utilizing an arc generated in the vacuum valve. Specifically, the base material 2 may be attached as a fixed contact and a movable contact of the vacuum valve, and the surface of the base material 2 may be arc-melted using an arc generated when the current is interrupted. Since arc melting occurs on the anode side when the current is interrupted, when the contact layer 3 is formed on both the fixed contact and the movable contact, the current is interrupted by switching the polarity. By using such a method, the contact material 1 having the contact layer 3 can be produced in a vacuum valve to which the contact material 1 is attached. Therefore, when the contact material 1 is produced separately using an arc melting apparatus or the like. Manufacturing efficiency is higher than that.
In addition, when arc melting the surface of the base material 2 in a vacuum valve, the degree of arc melting depends on the magnitude of the current to be cut off. Since the magnitude of the current to be cut off varies depending on the type of the vacuum valve, it is necessary to appropriately set it according to the type of the vacuum valve to be used.

  The contact material 1 according to the present embodiment having the above-described features includes a base material 2 having a contact layer 3 having a particle diameter of 1 μm or less, in which Cr fine particles 7 and intermetallic compound fine particles 8 are dispersed in a Cu base material 6. Since the surface hardness is increased by forming on the surface, it is possible to suppress the extension of the welding mark when the contact welding is peeled off and to prevent the deterioration of the withstand voltage performance in the advanced small current interruption. .

Embodiment 2. FIG.
The vacuum valve according to the present embodiment has a contact made of the contact material 1 according to the first embodiment.
Hereinafter, the vacuum valve of the present embodiment will be described with reference to the drawings.
FIG. 2 is a schematic cross-sectional view of the vacuum valve of the present embodiment. In FIG. 2, the vacuum valve 10 includes a shut-off chamber 11 inside. The shut-off chamber 11 is partitioned from a cylindrical insulating container 12 and metal lids 14a and 14b fixed to both ends of the insulating container 12 by sealing metal fittings 13a and 13b, and is vacuum-sealed. A fixed electrode rod 15 and a movable electrode rod 16 are provided in the blocking chamber 11 so as to face each other. A fixed electrode 17 and a movable electrode 18 are respectively attached to opposite surfaces of the fixed electrode rod 15 and the movable electrode rod 16 by brazing. A fixed contact 19 and a movable contact 20 are respectively attached to the contact portion between the fixed electrode 17 and the movable electrode 18 by brazing. The movable electrode rod 16 is provided with a bellows 21 that allows the movable electrode 18 to move in the axial direction while keeping the inside of the blocking chamber 11 in a vacuum-tight manner. In order to prevent arc vapor from adhering to the bellows 21, a metal bellows arc shield 22 is provided on the top of the bellows 21. In addition, in order to prevent the insulating container 12 from being covered with the arc vapor, the shielding chamber 11 is provided with a metal insulating container arc shield 23 so as to cover the fixed electrode 17 and the movable electrode 18. Yes.

  In the vacuum valve 10 having the above configuration, the fixed contact 19 and the movable contact 20 are formed using the contact material 1 of the first embodiment. The contact material 1 of Embodiment 1 is formed by forming a contact layer 3 having a particle diameter of 1 μm or less, in which Cr fine particles 7 and intermetallic compound fine particles 8 are dispersed in a Cu base material 6 on the surface of the base material 2. Since the hardness of the surface is increased, the vacuum valve 10 can suppress the extension of the welding marks when the contact welding is peeled off in the advanced small current interruption, and can prevent the withstand voltage performance from being lowered.

Hereinafter, although an Example and a comparative example demonstrate the detail of this invention, this invention is not limited by these.
Example 1
The mixture was mixed with Cr powder, Nb powder, and Cu powder (tie material) having a particle diameter of 45 μm or less through a sieve having a pore size of 45 μm, filled in a mold, and press-molded at a pressure of 140 MPa. Next, the compact was sintered at 1190 ° C. for 3 hours in a hydrogen gas atmosphere to obtain a porous sintered body. Next, a Cu plate is placed on the surface of the porous sintered body, heated at 1090 ° C. in a hydrogen gas atmosphere, and the base material is obtained by dissolving the Cu plate and infiltrating the inside of the porous sintered body. It was.
Next, the base material was machined to a size of an outer diameter of 25 mm and a thickness of 8 mm, and then attached as a fixed contact 19 and a movable contact 20 of the vacuum valve shown in FIG. Next, in the vacuum valve, the surface of the base material was arc-melted using an arc generated when the current was interrupted to form a contact layer. Here, arc melting was performed by setting the current to 10 kA and interrupting the current five times or more. Moreover, in order to form a contact layer in the contact material of both the fixed contact 19 and the movable contact 20, the polarity was switched to interrupt the current.

(Example 2)
A contact material and a vacuum valve were produced in the same manner as in Example 1 except that the magnitude of the current to be interrupted was 0.8 times that in Example 1 when arc melting was performed.
(Example 3)
A contact material and a vacuum valve were produced in the same manner as in Example 1 except that the magnitude of the current to be interrupted was 0.6 times that in Example 1 when arc melting was performed.

(Examples 4 and 5)
A base material having a predetermined composition was prepared by changing the blending ratio of the raw material powder used in Example 1. A contact material and a vacuum valve were produced in the same manner as in Example 1 except that this base material was used.
(Example 6)
A contact material and a vacuum valve were produced in the same manner as in Example 1 except that Ta powder (particle size of 45 μm or less) was used instead of Nb powder as raw material powder.
(Example 7)
A contact material and a vacuum valve were produced in the same manner as in Example 6 except that the magnitude of the current to be interrupted was 0.8 times that in Example 6 when performing arc melting.

(Example 8)
A contact material and a vacuum valve were produced in the same manner as in Example 6 except that the magnitude of the current to be interrupted was 0.6 times that in Example 6 when performing arc melting.
(Examples 9 and 10)
A base material having a predetermined composition was prepared by changing the blending ratio of the raw material powder used in Example 6. A contact material and a vacuum valve were produced in the same manner as in Example 6 except that this base material was used.

(Comparative Example 1)
The base material produced in Example 1 was used as a contact material.
(Comparative Example 2)
The base material produced in Example 6 was used as a contact material.
(Comparative Example 3)
A contact material and a vacuum valve were produced in the same manner as in Example 1 except that the magnitude of the current to be interrupted was about 1.2 times that in Example 1 when performing arc melting.
(Comparative Example 4)
A contact material and a vacuum valve were produced in the same manner as in Example 6 except that the magnitude of the current to be interrupted was about 1.2 times that in Example 6 when arc melting was performed.

(Comparative Example 5)
A contact material and a vacuum valve were produced in the same manner as in Example 1 except that the magnitude of the current to be interrupted was 2.0 times that in Example 1 when arc melting was performed.
(Comparative Example 6)
A contact material and a vacuum valve were produced in the same manner as in Example 6 except that the magnitude of the current to be interrupted was 2.0 times that in Example 6 when arc melting was performed.
(Comparative Example 7)
The mixture was mixed with Cr powder and Cu powder (tie material) having a particle diameter of 45 μm or less through a sieve having a pore size of 45 μm, filled in a mold, and press-molded at a pressure of 140 MPa. Next, the compact was sintered at 1190 ° C. for 3 hours in a hydrogen gas atmosphere to obtain a porous sintered body. Next, a Cu plate is placed on the surface of the porous sintered body, heated at 1090 ° C. in a hydrogen gas atmosphere, and the contact point material is obtained by dissolving the Cu plate and infiltrating the inside of the porous sintered body. It was. Next, the contact material was machined to a size of an outer diameter of 25 mm and a thickness of 8 mm.

In the vacuum valve having the contact material produced as described above, the advanced small current interruption performance was evaluated. Evaluation of the advanced small current interruption performance was evaluated based on the number of re-ignitions when the integrated small value of the ignition current was 2 As, the interruption current was 200 A, the recovery voltage was 120 kV, and the advanced small current was interrupted 100 times.
Moreover, about the contact material used for the vacuum bulb, the composition of the contact layer on the surface is identified using GD-OES (glow discharge emission analysis), and the thickness of the contact layer and the fine particles dispersed in the contact layer using SEM The maximum particle size of was measured. Here, the maximum particle size of the fine particles dispersed in the contact layer means the particle size of the largest fine particle among the Cr fine particles, Cr ₂ Nb fine particles, or Cr ₂ Ta fine particles.
The evaluation results are shown in Table 1.

In Table 1, the composition of the base material of “50Cu-45Cr-5Nb” in Example 1 is that the base material is composed of 50 mass% Cu base material, 45 mass% Cr particles, and 5 mass% Nb. Means. Similarly, the composition of the contact layer of “50Cu-40Cr-10Cr ₂ Nb” in Example 1 is such that the contact layer is 50% by mass of Cu base material, 40% by mass of Cr fine particles, and 10% by mass of Cr ₂ Nb fine particles. Means that it consists of

As shown in Table 1, the contact materials of Examples 1 to 10 have a refined structure in which the maximum particle size of the fine particles dispersed in the contact layer is 1 μm or less, and the number of reignition occurrences. There were few.
On the other hand, the contact materials of Comparative Examples 1, 2, and 7 did not form a contact layer, so the number of re-ignition occurrences increased. This is presumably because a lot of soft Cu base material is exposed on the surface of the contact material, and the welding marks are extended in the Cu base material when the welding of the contact is peeled off.
In the contact materials of Comparative Examples 3 to 6, since the contact layer did not have a desired fine structure, the number of re-ignitions was increased. This is because the maximum particle size of the fine particles dispersed in the contact layer is larger than 1 μm, and the dispersibility of the fine particles in the contact layer is lowered, so that when the contact weld is peeled off, the weld trace is extended in the Cu base material. It is thought that this is because it has been.

  Examining the above results, there is a correlation between the maximum particle size of the fine particles dispersed in the contact layer and the thickness of the contact layer. If the contact layer becomes too thick, the maximum of fine particles dispersed in the contact layer The particle size tends to increase. Therefore, in order to make the particle diameter of the fine particles dispersed in the contact layer 1 μm or less, it is considered that the thickness of the contact layer is preferably 100 μm or less.

  As can be seen from the above results, according to the present invention, it is possible to provide a vacuum valve contact material excellent in advanced small current interruption performance, and a vacuum valve having a contact made of a vacuum valve contact material having the characteristics. it can.

  DESCRIPTION OF SYMBOLS 1 Contact material, 2 Base material, 3 Contact layer, 4 Cr particle, 5 Metal particle, 6 Cu base material, 7 Cr fine particle, 8 Intermetallic compound fine particle, 10 Vacuum valve, 11 Shut-off chamber, 12 Insulation container, 13a, 13b Sealing bracket, 14a, 14b Metal lid, 15 Fixed electrode rod, 16 Movable electrode rod, 17 Fixed electrode, 18 Movable electrode, 19 Fixed contact, 20 Movable contact, 21 Bellows, 22 Arc shield for bellows, 23 Arc for insulating container shield.

Claims (5)

A base material in which at least one metal particle selected from Cr particles and Nb particles and Ta particles is dispersed in a Cu base material;
A contact layer formed on the base material, the Cr fine particles having a particle size of 1 μm or less, and at least one metal selected from the Cr ₂ Nb fine particles and the Cr ₂ Ta fine particles having a particle size of 1 μm or less A contact material for a vacuum valve, comprising a contact layer in which intermetallic fine particles are dispersed in a Cu base material.   The contact material for a vacuum valve according to claim 1, wherein the contact layer has a thickness of 100 μm or less.   The content of the Cr fine particles in the contact layer is 20% by mass or more and 50% by mass or less, and the content of the intermetallic compound fine particles is 1% by mass or more and 20% by mass or less. Contact material for vacuum valves as described in 1.   The contact material for a vacuum valve according to any one of claims 1 to 3, wherein the particle size of Cr particles and metal particles in the base material is more than 1 µm and not more than 100 µm.   A vacuum valve comprising a contact made of the contact material for a vacuum valve according to claim 1.

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