JP2002088437A - Contact material for vacuum valve and its production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a contact material for a vacuum valve combinedly having excellent large current breaking characteristics and large current conducting characteristics. SOLUTION: This contact material for a vacuum valve at least contains, by weight, 75 to 95% copper and a carbide containing at least either titanium carbide(TiC) or vanadium carbide(VC) by 5 to 25%. Further, <=5% chromium(Cr) is preferably incorporated therein. By controlling the composition of the contact material to the same range, both of large current breaking performance by the arc diffusing action of TiC or VC and large current conducting performance by Cu can be exhibited without being damaged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact material for a vacuum valve and a method for producing the same, and more particularly, to a contact material having both excellent large current interrupting characteristics and large current carrying characteristics and a method for producing the same.

[0002]

2. Description of the Related Art Generally, a method for producing a contact material for a vacuum valve is divided into a melting method and a sintering method. The melting method is a method for producing a contact material mainly composed of a conductive metal having a relatively low melting point such as copper (Cu). Among the melting methods, a vacuum melting method in which induction melting is performed in a vacuum is common. In the vacuum melting method, Cu-bismuth (Bi) -based or Cu-
Contact materials such as tellurium (Te) -selenium (Se) are manufactured. In recent years, a Cu-chromium (Cr) -based contact material has also been manufactured using an arc melting method.

On the other hand, the sintering method is used for producing a contact material in which such a relatively low-melting conductive component and a high-melting arc-resistant component are combined at the same volume ratio. In the sintering method, usually, a low-melting conductive metal is infiltrated into a skeleton-shaped compact formed by molding a powder mainly composed of a high melting point arc-resistant component to have a constant relative density, and then contacting the contact. Manufacture materials. Cu-tungsten (W) by sintering method
Contact materials such as silver-based, silver (Ag) -tungsten carbide (WC) -based, and Cu-Cr-based are manufactured. Also,
Cu-Cr based contact materials are also manufactured by a solid phase sintering method.

[0004] In the public information of JP-A-11-16455,
Cu with excellent high current interruption characteristics and low surge characteristics
An invention relating to a contact material of titanium carbide (TiC) -Cr system or Cu-vanadium carbide (VC) -Cr system is disclosed. Here, a method of infiltrating a molded body mainly composed of TiC or VC with a Cu—Cr alloy,
Alternatively, two methods are disclosed, in which powdery Cr particles are added to a molded body mainly composed of VC to infiltrate Cu. Further, since powder mainly composed of TiC or VC has poor moldability, a method of forming TiC or VC using a split mold is disclosed.

[0005]

However, in recent years, there has been an increasing demand for compact distribution equipment, and there has been a demand for a contact material having a large breaking current density. That is, there is a long-awaited need to develop a contact material having a higher breaking current density than a Cu-Cr-based contact material conventionally used for breaking large currents.

[0006] The Cu-TiC-based contact material disclosed in Japanese Patent Application Laid-Open No. H11-16455 has an excellent large-current interrupting property exceeding that of the Cu-Cr-based contact material. But T
Since a low surge property is prioritized by increasing the content of iC, sufficient large current carrying characteristics cannot be obtained. Therefore, it is not suitable for application to a vacuum valve having a large rated current of 2000 A or more.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and has as its object to provide a contact material for a vacuum valve, which has both excellent large current interrupting characteristics and large current carrying characteristics. It is an object of the present invention to provide a manufacturing method thereof.

[0008]

In order to achieve the above object, a first feature of the present invention is that copper having a weight ratio of 75 to 95% and titanium carbide (TiC) having a weight ratio of 5 to 25% are used. And a carbide containing at least one of vanadium carbides such as titanium carbide or vanadium carbide (VC).

According to the first feature of the present invention, when the composition of the contact material is within this range, the large current interruption performance due to the arc diffusion effect of titanium carbide or vanadium carbide and the large current conduction performance due to Cu can be obtained. Both can be exhibited without spoiling.

In the first aspect of the present invention, it is preferable that the contact material further includes chromium (Cr) having a weight ratio of 5% or less. By further adding Cr to the contact material, defects generated in the contact material can be minimized, and more excellent large current interruption characteristics can be obtained. Further, the titanium carbide or the vanadium carbide is in the form of particles having an average particle diameter of 200 μm or less, and is preferably dispersed in a copper matrix. By dispersing and arranging the raw material powders of titanium carbide or vanadium carbide in this particle size range, copper can be sufficiently diffused between the carbide particles at the time of sintering, and a copper matrix with few defects is formed. be able to.

A second feature of the present invention is that (a) a mixed powder obtained by mixing a Cu powder having an average particle diameter of 30 to 200 μm and a titanium carbide or vanadium carbide powder having an average particle diameter of 30 to 200 μm. (B) a molding step of applying pressure to the mixed powder to form a molded body; and (c) sintering the molded body at a temperature of 950 ° C. or more and the melting point of copper and a sintered body. And a sintering step for producing a contact material for a vacuum valve.

In the second aspect of the present invention, it is preferable that the method further comprises a reducing step of reducing the Cu powder in hydrogen at a temperature of 200 to 500 ° C. before the mixing step.
By this reduction step, the wettability between Cu and titanium carbide or vanadium carbide is improved, and defects at the interface can be reduced. After the mixing step, it is desirable to repeat the forming step and the sintering step two or more times. Defects in the structure can be further reduced by repeating the forming step and the sintering step two or more times. The sintering process
It is desirable to carry out in a vacuum atmosphere of 2 × 10 ⁻¹ Pa or less. In the mixing step, it is desirable to further mix chromium (Cr) powder having an average particle diameter of 30 to 200 μm. The added Cr particles diffuse into the titanium carbide particle surface during sintering, thereby improving the adhesion between the copper matrix and the titanium carbide particles and suppressing defects at the interface. Further, the mixing step includes a step of mixing the powder of Cr and the powder of titanium carbide or vanadium carbide;
desirably, a step of mixing a mixed powder of r and titanium carbide or vanadium carbide with a Cu powder. By mixing in this order, the possibility that the titanium carbide powder and the Cr powder are adjacent to each other in the compact increases, and the diffusion of Cr to the surface of the titanium carbide particles can be promoted. In the sintering step, it is desirable to dissolve the compact on a crucible on which alumina powder is laid. By this method, the reaction between the crucible and the molded body can be prevented.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. In the embodiment of the present invention,
First, the structure of the contact portion of a vacuum valve using a contact material for a vacuum valve is shown, and Examples 1 to 23 and Comparative Example 1 are shown.
To 15 and copper (Cu) -titanium carbide (Ti
The contact material made of C) or Cu-TiC-chromium (Cr) will be described as an example.

(Structure of Vacuum Valve) FIG. 1 is a sectional view showing the structure of a contact portion of a vacuum valve using a contact material according to an embodiment of the present invention. As shown in FIG. 1, one contact 13a of the vacuum valve is connected to the tip of the electrode 7, and the electrode 7 is connected to the tip of the conductive rod 5. The other contact 13b of the vacuum valve is connected to the tip of the electrode 8, and the electrode 8 is connected to the tip of the conductive rod 6. Conductive rods 5, 6
Are arranged linearly so as to be connected to each other at the contacts 13a and 13b. Bellows 9 is arranged around conductive bar 6 at a predetermined interval. The bellows 9 is made of an insulator that can be extended and contracted in the linear direction of the electric rod 6. An arc shield 10 is arranged around the bellows 9 at a predetermined interval. Arc shield 10
Is a conductor for adjusting the potential distribution of the contact portion,
A part thereof is connected to the conductive rod 6. One end of the bellows 9 is connected to the arc shield 10. An arc shield 11 is arranged around the arc shield 10 at a predetermined interval. The arc shield 11 is also a conductor for adjusting the potential distribution of the contact portion, and is arranged so as to surround the conductive rods 5, 6, the electrodes 7, 8 and the contacts 13a, 13b. The inside of the arc shield 11 forms the cutoff chamber 1. Around the arc shield 11, a cylindrical insulating container 2 is arranged at a predetermined interval. Lids 4a, 4b are connected to both ends of the insulating container 2 via sealing fittings 3a, 3b. The arc shield 11 is connected to the lid 4a, and the other end of the bellows 9 is connected to the lid 4b. The conductive rod 5 is connected to the lid 4a. When the conductive rod 6 moves in a linear direction, the bellows 9 expands and contracts, and the contact / contact between the contact 13a and the contact 13b /
Separation is controlled.

(Basic Process of Manufacturing Method of Contact Material) FIG.
1 is a flowchart showing basic steps of a method for manufacturing a contact material for a vacuum valve according to an embodiment of the present invention. FIG.
As shown in the above, the contact material for a vacuum valve can be manufactured by the following steps.

(A) First, in step S1, a powder of copper (Cu) having an average particle size of 30 to 200 μm and a powder of titanium carbide (TiC) having an average particle size of 30 to 200 μm are mixed. Perform a mixing process to make C
The average particle diameters of u and TiC do not need to be the same, and it is sufficient if the average particle diameters of both are within the range of 30 to 200 μm. The weight ratio of Cu to TiC may be within the range of 75 to 95% for Cu and 25 to 5% for TiC. Further, although not shown in FIG. 2, before the mixing process in step S1, Cu
Is reduced in hydrogen at a temperature of 200 to 500 ° C. In the basic process, the average particle size was 45 μm.
And a TiC powder having an average particle diameter of 45 μm are mixed. The weight ratio of Cu was 85% and TiC was 15%.
%. Further, the temperature during the reduction treatment is 300 ° C.

(B) Next, in step S2, Cu
-A molding step of applying pressure to the mixed powder of TiC to form a molded body is performed. The mixed powder is put into a metal split mold or a rubber mold and pressure is applied thereto. The metal split mold is composed of a container into which the mixed powder enters, and a lid for applying pressure to the mixed powder in the container. The mixed powder is formed into a shape composed of a container and a lid. On the other hand, in the case of a rubber mold, the mold containing the mixed powder is placed in oil or water, and pressure is applied to the oil and water to apply pressure to the mixed powder in the rubber mold to form a molded body. make. When a rubber mold is used, pressure is applied using oil and water as a medium, so that pressure is uniformly applied to the mixed powder and a molded body having a uniform relative density can be produced. In the basic process, the pressure applied to the mixed powder is about 8 tons, and the shape of the compact is 52.5 mm in diameter.
mm and a disk shape with a thickness of 7 mm.

(C) Finally, in step S3, a sintering step of sintering the formed body at a temperature of 950 ° C. or higher and lower than the melting point of copper to form a sintered body is performed. Specifically, the infiltration material and the formed body are laminated and arranged in a crucible, and 950-10
The molded body is sintered at a sintering temperature of 50 ° C. in an atmosphere having a degree of vacuum of 2 × 10 ⁻¹ Pa or less. The melting point of copper is 10
Although the temperature is about 83 ° C., by raising the temperature of the furnace to 1050 ° C., the molded body can be sintered at a temperature equal to or lower than the melting point of copper. When the temperature of the furnace is set to 1050 ° C. or higher, the temperature of the compact may be higher than the melting point of copper. In the basic process, the compact is sintered at a sintering temperature of 1000 ° C. by increasing the temperature of the furnace to 1050 ° C. Alumina powder is spread between the crucible and the molded body as a squeeze powder to avoid a reaction between the carbon crucible and the molded body. In Examples 20 to 23 and Comparative Examples 12 to 15, the infiltration material, the compact, and the Cr powder were laminated and sintered. After the mixing step, the molding step and the sintering step were repeated twice.

(Evaluation Method of Material Properties / Electrical Properties) The basic steps of the manufacturing method described with reference to FIG.
In the following Examples and Comparative Examples, production was performed while changing any of the production parameters. The contact material according to each of the examples and the comparative examples was evaluated for the following material properties and electrical properties. The above basic steps are shown as a second embodiment.

<Evaluation Method of Conductivity> The conductivity of the manufactured contact material was measured by an overcurrent method.

<Relative Density Evaluation Method> The relative densities of contact materials having different compositions and being systematically homogeneous were evaluated. Specifically, the relative density of the entire contact material was evaluated by measuring the local relative density from a photograph of the structure of the contact material in the radial direction. By examining in advance the correlation between the density measurement result by Archimedes method and the relative density calculated from the composition analysis result, the local relative density can be determined for the same material as the amount of pores examined in the micrograph of the structure with a scanning electron microscope. The relative density of the entire contact material can be evaluated from the measurement of the contact material.

<Oxygen Content Evaluation Method> The oxygen content of the prepared contact material was measured by an infrared absorption method.

<Evaluation Method for Specified Interruption> A contact material having a diameter of 50 mm was processed and taken out from the contact material, incorporated into a vacuum valve as the contacts 13a and 13b shown in FIG. 1, and the interruption characteristics were evaluated by a composite interruption test. In the evaluation method, the breaking current value was gradually increased from a low current value (5 kA), and the current value at which the breaking failed first was taken as the breaking current value. Then, it was evaluated as a relative value when the breaking current value of the contact material according to Example 2 (basic process) was set to 1, and 0.8 or more was regarded as a pass.

<Electrification Characteristics Evaluation Method> A contact material having a diameter of 50 mm was processed and taken out from the contact material, incorporated into a vacuum valve as the contacts 13a and 13b shown in FIG. 1, and the cutoff characteristics were evaluated. A rated current was passed through the vacuum valve, and the temperature rise of the energized shaft in a steady state was measured. Then, it was evaluated as a relative value when the temperature rise value of the contact material according to Example 2 (basic process) was set to 1, and 1.2 or less was regarded as a pass.

(Examples 1 to 3 and Comparative Examples 1 and 2) FIGS. 3 and 4 are tables summarizing the production parameters and the evaluation results of material properties and electrical properties of each of the examples and comparative examples.
Hereinafter, each example and each comparative example will be described with reference to FIGS. 3 and 4. First, Examples 1 to 3 and Comparative Example 1,
In 2, the weight ratio of Cu of the Cu-TiC-based contact material was changed in the range of 70 to 97%. Needless to say, the weight ratio of TiC at this time varies in the range of 30 to 3%. Other manufacturing parameters are the same as in the basic process. Specifically, as shown in FIG.
The weight ratio of Cu and TiC (Cu: TiC) was 7 in Comparative Example 1.
0:30, 75:25 in the first embodiment, and the second embodiment
Is 85:15, Example 3 is 95: 5, and Comparative Example 2 is 97: 3. 75-95% by weight of Cu
All of the contact materials according to Examples 1 to 3 in the range of (1) to (4) had good breaking characteristics and current-carrying characteristics. However, the contact material according to Comparative Example 1, in which the weight ratio of Cu is 70%, cannot obtain sufficient current-carrying performance because the ratio of TiC that inhibits current-carrying characteristics is too high. On the other hand, when the weight ratio of Cu is 9
Comparative Example 2, which is 7%, has a too low TiC ratio.
The effect of improving the barrier properties by TiC was not sufficiently obtained.

(Examples 4 to 6, Comparative Examples 3 and 4) Next, in Examples 4 to 6 and Comparative Examples 3 and 4, the average particle diameter of the TiC powder used as a raw material in the mixing step was kept at 45 μm. The average particle size of the raw material Cu powder was changed in the range of 25 to 250 μm. Other manufacturing parameters are the same as in the basic process. Specifically, the average particle size of the Cu powder was 25 μm in Comparative Example 3, 30 μm in Example 4,
In the fifth embodiment, the thickness is 100 μm, and in the sixth embodiment, the thickness is 200 μm.
In Comparative Example 4, the thickness was 250 μm. The contact materials according to Examples 4 to 6, in which the average particle size of the Cu powder was in the range of 30 to 200 µm, were all excellent in the breaking characteristics and the conduction characteristics. However, the contact material according to Comparative Example 3 in which the average particle size of the Cu powder was 25 μm had a large oxygen content, and was not able to obtain sufficient blocking performance. On the other hand, the contact material according to Comparative Example 4 in which the average particle size of the Cu powder was 250 μm could not obtain a sufficiently high relative density of the formed body, and the temperature rise during energization was large, so that the evaluation of energization characteristics was rejected It became.

(Examples 7 to 9 and Comparative Examples 5 and 6) Next, in Examples 7 to 9 and Comparative Examples 5 and 6, the average particle size of the Cu powder as a raw material used in the mixing step was kept at 45 μm. Keeping this, the average particle size of the TiC powder was changed in the range of 25 to 250 μm. Other manufacturing parameters are the same as in the basic process. Specifically, the average particle size of TiC was determined by comparing Comparative Example 5
In Example 7, it was 30 μm, in Example 7, it was 100 μm, in Example 9, it was 200 μm,
In Comparative Example 6, the thickness was 250 μm. All of the contact materials according to Examples 7 to 9 in which the average particle size of the TiC powder was in the range of 30 to 200 µm had good breaking characteristics and current-carrying characteristics. However, the contact material according to Comparative Example 5, in which the average particle size of the TiC powder was 25 μm, had an extremely high oxygen content, and did not provide sufficient blocking performance. On the other hand, the contact material according to Comparative Example 6 in which the average particle size of the TiC powder is 250 μm,
Sufficient blocking performance could not be obtained due to local temperature rise at the center of the coarse TiC particles.

(Examples 10 to 12, Comparative Example 7) Next, in Examples 10 to 12 and Comparative Example 7, the sintering temperature during the sintering step was changed in the range of 900 to 1050 ° C. Other manufacturing parameters are the same as in the basic process. Specifically, the sintering temperature was set to 900 ° C. in Comparative Example 7, and Example 1 was used.
0 is 950 ° C., and Example 11 is 1000 ° C.
In Example 12, the temperature was set to 1050 ° C. The sintering temperature is 950
All the contact materials according to Examples 10 to 12 in the range of 1050 ° C. had good breaking characteristics and current-carrying characteristics.
However, the contact material according to Comparative Example 7, in which the sintering temperature was 900 ° C., was not able to obtain a sufficient sintering density and had a high oxygen content, so that the breaking characteristics were extremely poor.

(Examples 13 to 15, Comparative Examples 8 and 9) Next, in Examples 13 to 15 and Comparative Examples 8 and 9, the reduction temperature for reducing the raw material Cu powder in hydrogen was set to 150 to 600.
The temperature was varied in the range of ° C. Other manufacturing parameters are the same as in the basic process. Specifically, the reduction temperature was 150 ° C. in Comparative Example 8, 200 ° C. in Example 13, 300 ° C. in Example 14, 500 ° C. in Example 15, and 600 ° C. in Comparative Example 9. Reduction temperature 200 ~
The contact materials according to Examples 13 to 15 in the range of 500 ° C. all had good breaking characteristics and current-carrying characteristics. However, the contact material according to Comparative Example 8, in which the reduction temperature was 150 ° C., was insufficient in hydrogen reduction, so that the oxygen content was large, and sufficient cutoff performance could not be obtained. On the other hand, the contact material according to Comparative Example 9, in which the reduction temperature was 600 ° C., was not sufficiently high in sintering density because the Cu particles were bonded and coarsened, and the breaking characteristics were insufficient. .

(Examples 16 and 17, Comparative Example 10)
In Examples 16 and 17 and Comparative Example 10, the number of times the molding step and the sintering step were repeated after the mixing step was changed in the range of 1 to 3 times. Other manufacturing parameters are the same as in the basic process. Specifically, the number of repetitions of the molding step and the sintering step was set to one in Comparative Example 10, two in Example 16, and three in Example 17. Here, one repetition means that the molding step and the sintering step are performed once each after the mixing step, and the molding step and the sintering step are not repeated. The contact material according to Comparative Example 10 in which repetitive molding and firing were not performed could not obtain a sufficiently large relative density, and failed both the cutoff characteristics and the conduction characteristics. However, Example 1 in which molding and firing were repeated two to three times
The contact materials according to Nos. 6 and 17 had sufficiently high relative densities, and had good breaking characteristics and current-carrying characteristics. It is presumed that good cutoff characteristics and current-carrying characteristics can be similarly obtained when repeated four or more times.

(Examples 18 and 19, Comparative Example 11) The degree of vacuum in the sintering step was changed in the range of 2 × 10 ^{−2 to} 3 × 10 ⁻¹ Pa. Other manufacturing parameters are the same as in the basic process. Specifically, the degree of vacuum in the sintering step was set to 2 × 10 ⁻² Pa in Example 18;
In the comparative example 11, 3 × 10 ^-1 Pa was set.
⁻¹ Pa. The degree of vacuum in the sintering process is 2 × 10
Each of the contact materials according to Examples 18 and 19 having a pressure of ^-1 Pa or less had good breaking characteristics and current-carrying characteristics. However, the contact material according to Comparative Example 11, in which the degree of vacuum was 3 × 10 ⁻¹ Pa, had a large oxygen content and could not obtain sufficient blocking performance. Incidentally, 2 × ¹⁰ when carrying out the sintering step also in -1 Pa than the high-vacuum atmosphere, in Example 18,
It is presumed that good breaking characteristics and good current-carrying characteristics can be obtained as in the case of No. 19.

(Examples 20 and 21, Comparative Example 12)
Cu powder and TiC are used as raw material powders to be mixed in the mixing step.
Cu-T prepared by further mixing Cr powder in addition to powder
An experiment performed on an iC-Cr contact material will be described. First, in Examples 20 to 21 and Comparative Example 12, the weight ratio of TiC was kept constant at 15%, the weight ratio of Cu was changed in the range of 84 to 75%, and the weight ratio of Cr was changed in the range of 1 to 10%. Was. Other manufacturing parameters are the same as in the basic process. Specifically, in Example 20, Cu
In Example 2, the weight ratio of Cr was 84% and the weight ratio of Cr was 1%.
In Example 1, the weight ratio of Cu was 80%, and the weight ratio of Cr was 5%. In Comparative Example 12, the weight ratio of Cu was 75%, and the weight ratio of Cr was 10%. In the contact materials according to Examples 20 and 21 in which the weight ratio of Cr was 5% or less, although the conductivity was decreased by the addition of Cr, the relative density was increased, so that the current-carrying characteristics could be satisfied. . In addition, since the oxygen content can be suppressed low due to the increase in the relative density, the cutoff characteristic is C
This is more improved than when r is not added. on the other hand. Cr
The contact material according to Comparative Example 12 in which the weight ratio of
Sufficient current-carrying performance was not obtained.

(Example 22, Comparative Examples 13 and 14)
In Example 22, Comparative Examples 13 and 14, the order of mixing Cu, TiC, and Cr in the mixing step was changed. The mixing was performed without changing the weight ratio of Cu: TiC: Cr at a ratio of 83: 15: 2. Other manufacturing parameters are the same as in the basic process. Specifically, in Example 22, first, Cu powder was further added to a mixed powder obtained by gradually adding and mixing TiC powder to Cr powder. Comparative Example 13
Then, first mix Cu powder with Cr powder,
C powder was added and mixed. In Comparative Example 14, first, TiC powder was mixed with Cu powder, and further, Cr powder was added and mixed. In the contact material according to Example 22, the probability that the Cr particles were adjacent to the TiC particles in the molded body was increased, so that diffusion of Cr to the surface of the TiC particles was promoted, and the wettability of the interface between Cu and TiC was improved. Was. In addition, it was possible to produce a material having a low oxygen content and a high relative density. Therefore, sufficient cutoff characteristics and conduction characteristics were obtained. On the other hand, the contact materials according to Comparative Examples 13 and 14 did not have sufficient sintering density, and had insufficient breaking performance.

(Example 23, Comparative Example 15) Next, the case where the compact is placed on alumina dust during sintering and treated, and the case where it is placed directly on a carbon crucible without using alumina dust And evaluated. The contact material according to Example 23, in which the compact was placed on alumina dust, had good electrical conductivity, relative density, and oxygen content, and obtained sufficient breaking performance and current-carrying performance. However, in the case of the contact material according to Comparative Example 15 in which the molded body was directly placed in the carbon crucible, the contact material reacted with the crucible and was fixed, making it impossible to manufacture the contact.

As described above, the contact material for a vacuum valve according to the embodiment of the present invention has a weight ratio of 75 to 95.
% Of copper (Cu) and titanium carbide (TiC) having a weight ratio of 5 to 25%, so that both the large current interrupting performance by the arc diffusion action of TiC and the large current carrying performance by Cu are improved. It can be demonstrated without loss. The contact material is made of chromium (C
By further having r), defects generated in the contact material can be minimized, and more excellent large current interruption characteristics can be obtained. TiC has an average particle size of 2
By having a particle size of 00 μm or less and being dispersed in the copper matrix, Cu can sufficiently diffuse between the TiC particles during sintering, and a copper matrix with few defects can be formed. Further, by repeating the forming step and the sintering step two or more times, defects in the structure can be further reduced. By subjecting the Cu powder to a reduction treatment at a temperature of 200 to 250 ° C. in hydrogen before the mixing step, the wettability between TiC and Cu is improved, and defects at the interface can be reduced.

In the embodiment of the present invention, Cu-T
Examples and comparative examples relating to iC and Cu-TiC-Cr-based contact materials have been described. However, the present invention is not limited to this, and it is clear from experiments performed by the inventor that similar effects can be obtained even when vanadium carbide (VC) is used instead of TiC.

[0037]

As described above, according to the present invention, it is possible to provide a contact material for a vacuum valve having both excellent large current interrupting characteristics and large current carrying characteristics, and a method of manufacturing the same.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration of a contact portion of a vacuum valve into which a contact material according to an embodiment of the present invention is incorporated.

FIG. 2 is a flowchart showing basic steps of a method for manufacturing a contact material for a vacuum valve according to an embodiment of the present invention.

FIG. 3 is a table summarizing production parameters and evaluation results of material characteristics and electric characteristics of each of Examples and Comparative Examples according to the embodiment of the present invention (part 1).

FIG. 4 is a table summarizing manufacturing parameters and evaluation results of material characteristics and electrical characteristics of each of the examples and comparative examples according to the embodiment of the present invention (part 2).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shutoff room 2 Insulating container 3a, 3b Sealing fitting 4a, 4b Lid 5, 6 Conductive rod 7, 8 Electrode 9 Bellows 10, 11 Arc shield 13a, 13b Contact

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H01H 11/04 H01H 11/04 D 33/66 33/66 B // B22F 1/00 B22F 1/00 C C22C 9 / 00C22C 9/00 (72) Inventor Atsushi Yamamoto 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Works Co., Ltd. Reference) 4K018 AA04 AB02 AC01 BA02 BA11 BA20 BB04 BC01 BC12 DA11 DA32 DA39 EA51 KA34 4K020 AA22 AC04 BB29 5G023 AA05 BA11 CA09 CA21 CA33 5G026 BA01 BB02 BB14 BB18 BB30 BC05 BC09 5G050 AA01 BA03 A03 AA03 AA03 AA18 AA18 AA13 AA18 AA18 AA13 AA13 AA18

Claims (13)

[Claims] 1. A contact material for a vacuum valve, comprising at least copper having a weight ratio of 75 to 95% and a carbide having a weight ratio of 5 to 25% containing at least one of titanium carbide and vanadium carbide. 2. The contact material for a vacuum valve according to claim 1, further comprising chromium having a weight ratio of 5% or less. 3. The titanium carbide or the vanadium carbide is in the form of particles having an average particle size of 200 μm or less,
The contact material for a vacuum valve according to claim 1, wherein the contact material is dispersed in a copper matrix. 4. A mixing step of mixing a copper powder having an average particle diameter of 30 to 200 μm with a titanium carbide or vanadium carbide powder having an average particle diameter of 30 to 200 μm to form a mixed powder; It is characterized by having at least a forming step of forming a molded body by applying pressure and a sintering step of sintering the formed body at a temperature of 950 ° C. or higher and a melting point of copper or lower to form a sintered body. Manufacturing method of contact material for vacuum valve. 5. The contact material for a vacuum valve according to claim 4, further comprising a reduction step of reducing the copper powder in hydrogen at a temperature of 200 to 500 ° C. before the mixing step. Manufacturing method. 6. The method according to claim 4, wherein the forming step and the sintering step are repeated twice or more after the mixing step. 7. The method for manufacturing a contact material for a vacuum valve according to claim 4, wherein the sintering step is performed in a vacuum atmosphere of 2 × 10 ⁻¹ Pa or less. 8. In the mixing step, the average particle size is 30.
5. The method for producing a contact material for a vacuum valve according to claim 4, further comprising mixing chromium powder having a thickness of from 200 to 200 [mu] m. 9. The mixing step includes: mixing the chromium powder with the titanium carbide or the vanadium carbide powder; and mixing the chromium and the titanium carbide or the vanadium carbide mixed powder with the copper powder. 9. The method for producing a contact material for a vacuum valve according to claim 8, comprising a step of mixing. 10. The vacuum valve according to claim 8, further comprising a reduction step of reducing the copper powder in hydrogen at a temperature of 200 to 500 ° C. before the mixing step. Manufacturing method of contact material. 11. The method according to claim 8, wherein the forming step and the sintering step are repeated two or more times after the mixing step. 12. The method of manufacturing a contact material for a vacuum valve according to claim 8, wherein the sintering step is performed in a vacuum atmosphere of 2 × 10 ⁻¹ Pa or less. 13. The method for producing a contact material for a vacuum valve according to claim 8, wherein in the sintering step, the compact is melted on a crucible on which alumina powder is laid.