JP2015138682A - Electrode material and method for manufacturing electrode material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an electrode material by which an electrode material superior in voltage resistance and deposition resistance can be manufactured at lower cost.SOLUTION: A method for manufacturing an electrode material comprises the steps of: molding mix powder consisting of a mixture of Cu powder, Cr powder, powder of refractory metal (e.g. Mo), and Te powder by compression; and sintering the resultant mold in a non-oxidizing atmosphere at a temperature of a Cu melting point or lower. As the Cr powder mixed in the mix powder, Cr powder of particles having diameters of 40 μm or smaller, of which the volume relative particle amount is less than 10% is used. In the mix powder, the Cr powder is mixed by 10 to 50 wt.%, the refractory metal powder is mixed by 1 to less than 7 wt.%, and the Te powder is mixed by 0.01 to 0.2 wt.%.

Description

  The present invention relates to an electrode material used for an electrode such as a vacuum circuit breaker and a method for producing the electrode material.

  The copper-molybdenum-chromium (hereinafter referred to as Cu-Mo-Cr) composite metal is a conventionally known copper-bismuth (Cu-Bi) composite metal, copper-tungsten (Cu-W) composite metal, etc. In comparison, it has been known as an electrode material for a vacuum circuit breaker having excellent electric resistance such as current interruption capability and dielectric strength in addition to good welding resistance (for example, Patent Documents 1-3).

  Further, the welding resistance of the electrode material is improved by adding tellurium (Te) having a low melting point to the electrode material of the vacuum circuit breaker (for example, Patent Document 4).

  As a method for producing a high-quality, high-performance electrode material using this Cu—Mo—Cr composite metal, a sintering method (for example, Patent Document 2) and an infiltration method (for example, Patent Document 3) have been proposed. Yes.

  In the sintering method, a mixed powder of a plurality of high melting point metals (for example, Mo and Cr) is heated to a melting point of Cu or higher, and a reaction product (for example, a MoCr alloy composition) obtained in the preliminary sintering process. And a sintering step of heating a molded body obtained by pressure-molding the mixed powder obtained in the mixing step to a temperature below the melting point of Cu in a non-oxidizing atmosphere. Thus, an electrode material is manufactured.

  Further, in the infiltration method, the mixing step of uniformly mixing the Mo powder and the Cr powder, the forming step of press-molding the mixture obtained in the mixing step, and the molded body obtained in the forming step are 1100 to 1200 ° C. A preliminary sintering step of sintering at a temperature, and a Cu thin plate is disposed on the preliminary sintered body obtained in the preliminary sintering step, and the Cu is liquid-phased in the temporary sintered body by maintaining the temperature at 1100 to 1200 ° C. An electrode material is manufactured by a Cu infiltration process in which sintering and infiltration are performed. The infiltration method is used for the production of an electrode material for a vacuum circuit breaker that requires high voltage, large capacity and high frequency interruption characteristics.

JP 59-27418 Japanese Patent Laid-Open No. 4-334832 JP 2012-7203 A JP 2009-76218 A JP 2002-373537 A JP 2002-180150 A

  However, in the sintering method, it takes time to perform the preliminary sintering step, and when the temporary sintered body is pulverized, it is pulverized and classified in an environment in which the pulverizing atmosphere is controlled. Manufacturing cost may be high.

  Moreover, since the infiltration method performs a temporary sintering process, a Cu infiltration process, or the like, there is a possibility that the manufacturing cost of the electrode material is increased.

  When manufacturing an electrode contact with an electrode material containing Cu as a main component and containing one type of refractory metal, Cu electrode and refractory metal powder (for example, Cr powder) are mixed and the electrode contact is manufactured by press sintering. The On the other hand, as described in Patent Document 3, when an electrode contact is made of an electrode material containing Cu as a main component and containing two or more kinds of refractory metals, the refractory metal powder is simply mixed. However, the press sintering method has many pores inside the electrode material and cannot be used as an electrode contact.

  The reason why there are many pores inside the electrode material is that Cr is diffused into the high melting point metal (for example, Mo) by sintering, Cr particles become small, and the part becomes voids, or it accompanies the sintering. It is conceivable that the voids of the molded body are not filled with Cu due to the shrinkage. An electrode contact formed of an electrode material having a void in the interior may cause the brazing between the electrode contact and the electrode rod to be defective due to the brazing material entering the electrode contact.

  As described above, a technique for adding a refractory metal excellent in withstand voltage to improve electrical characteristics such as withstand voltage of the electrode material has been devised, but for reasons such as an increase in manufacturing cost, In many cases, it cannot be applied to products such as vacuum circuit breakers. Therefore, there is a demand for an electrode material that can be manufactured at a relatively low cost and has excellent electrical characteristics such as voltage resistance.

  Further, receiving and transforming equipment such as a vacuum circuit breaker is required to be further reduced in size and price. Therefore, it is possible to reduce the strength of the electrode material provided in the vacuum circuit breaker and the like, and to reduce the peeling force when the electrode material is welded by Joule heat, thereby reducing the size of the operation mechanism unit for opening and closing the electrode. It is being considered.

  In view of the above circumstances, an object of the present invention is to provide a technique that contributes to improvement of voltage resistance and welding resistance of an electrode material.

  One aspect of the electrode material of the present invention that achieves the above object is 10 to 50% by weight of Cr powder having a particle size of 40 μm or less and a volume relative particle amount of less than 10%, and 1 to 7% by weight. A mixture containing less than wt% refractory metal powder and 0.01 to 0.2 wt% Te, with the balance being Cu powder and unavoidable impurities, compression molded and sintered. It is a feature.

  Another aspect of the electrode material of the present invention that achieves the above object is that the refractory metal is Mo, W, Nb, Ta, V, Zr, Be, Hf, Ir, Pt, Ti in the electrode material. , Si, Rh, and Ru, at least one selected from the group consisting of Si, Rh, and Ru.

  Another aspect of the electrode material of the present invention that achieves the above object is characterized in that, in the electrode material, the particle diameter of the refractory metal powder is 30 μm or less.

  Another aspect of the electrode material of the present invention that achieves the above object is characterized in that, in the electrode material, an average particle diameter of the Cr powder is 150 μm or less.

  Moreover, one aspect of the method for producing the electrode material of the present invention that achieves the above object is as follows. A mixing step of mixing refractory metal powder of not less than 7% by weight and less than 7% by weight, 0.01 to 0.2% by weight of Te, and the remaining Cu powder, and a mixture obtained in the mixing step It has the forming process which press-molds, and the sintering process which sinters the molded object obtained at the said forming process.

  Further, one aspect of the vacuum interrupter of the present invention that achieves the above object is a vacuum interrupter provided with a fixed electrode and a movable electrode that is disposed so as to be detachably attached to the fixed electrode in a vacuum vessel, At least one of the fixed electrode and the movable electrode is composed of 10 to 50% by weight of Cr powder having a particle diameter of 40 μm or less and a volume relative particle amount of less than 10%, and 1 to 7% by weight. % Of refractory metal powder and 0.01 to 0.2% by weight of Te, with the balance being Cu powder and inevitable impurities, a mixture formed by pressing and sintering. It is characterized by that.

  According to the above invention, it can contribute to the improvement of the voltage resistance and welding resistance of an electrode material.

It is a schematic sectional drawing of the vacuum interrupter which concerns on embodiment of this invention. It is a measurement result of the particle size distribution of Cr powder A. It is a measurement result of the particle size distribution of Cr powder B. 2 is a photomicrograph of a cross section of the electrode material of Example 1. It is a characteristic view which shows the change of the tensile strength by adding Te.

  An electrode material, an electrode material manufacturing method, and a vacuum interrupter according to an embodiment of the present invention will be described in detail with reference to the drawings.

  The inventors considered the grain size of Cr, the diffusion of Cr during sintering, and examined the improvement in withstand voltage from the optimum sintering temperature and the blending amount of Cu, Cr, refractory metal (for example, Mo), Furthermore, the present invention has been completed by examining the improvement of the welding resistance by adding low melting point metal Te.

  An electrode material and an electrode material manufacturing method according to an embodiment of the present invention are obtained by pressure-molding a mixed powder obtained by mixing Cu powder, Cr powder, Te powder and refractory metal powder, and non-oxidizing the obtained molded body. By firing at a temperature below the melting point of Cu in a neutral atmosphere, an electrode material excellent in voltage resistance and welding resistance is manufactured at a relatively low cost.

  Specifically, as the Cr powder to be mixed with the mixed powder, a Cr powder having a particle size of 40 μm or less and a volume relative particle amount of less than 10% is used. %, And an electrode material having a structure in which a solid solution of Cr and a refractory metal is dispersed in a Cu phase can be produced. Furthermore, the presence of a very small amount of Te in the grain boundaries and voids of the Cu—Cr—refractory metal reduces the material strength of the electrode material, reduces the peeling force during welding between the electrodes, This greatly improves the welding resistance.

  As the Cu powder, for example, a commercially available electrolytic copper powder is used. The shape of the Cu powder is not necessarily a dendritic shape, and may be a spherical shape or an irregular shape such as an atomized powder.

  As the Cr powder, for example, one having an average particle size of 150 μm or less (however, the volume relative particle amount of particles having a particle size of 40 μm or less is less than 10%) is used. By mixing the Cr powder with the mixed powder in the range of 10 wt% or more and 50 wt% or less, more preferably in the range of 20 wt% or more and 30 wt% or less, an electrode material having excellent voltage resistance can be manufactured. An electrode material in which the mixed amount of Cr powder is in the range of 20 wt% or more and 30 wt% or less is, for example, an electrode material optimal for a vacuum interrupter (VI) rated at 12 to 36 kV.

  As the Mo powder, a Mo powder having a particle size of 30 μm or less, more preferably, a Mo powder having a maximum particle size of less than 4 μm is used. By mixing the Mo powder with the mixed powder in the range of 1 wt% or more and less than 7 wt%, more preferably in the range of 1 wt% or more and 5 wt% or less, an electrode material excellent in voltage resistance can be manufactured. In the examples, Mo will be described as an example of a refractory metal. However, similar to Mo, it has fire resistance and has a characteristic of making Cr particles fine (that is, a factor for forming voids in the electrode material). The same effect can be obtained even when a metal having a property to be obtained is used instead of the Mo powder. Examples of such a refractory metal include tungsten (W), niobium (Nb), tantalum (Ta), vanadium (V), zirconium (Zr), beryllium (Be), hafnium (Hf), and iridium (Ir). Platinum (Pt), titanium (Ti), silicon (Si), rhodium (Rh), ruthenium (Ru), and the like.

  Since Te powder is a low melting point metal, it is volatilized in a trace amount from the surface of the pressed body during sintering. Therefore, it is preferable to use a Te powder having a particle size smaller than the Cr particle size. When a finer powder is used, the mixing property is considered good. By mixing Te powder with the mixed powder in the range of 0.01 wt% or more, more preferably 0.01 wt% or more and 0.2 wt% or less, an electrode material excellent in welding resistance can be manufactured. The addition amount of Te powder can be set to an optimum amount (0.2 wt% or more) according to the vacuum degree of the sintering furnace. However, since Te is an expensive metal, it is desirable to mix it with the mixed powder in the range of 0.01 wt% or more and 0.2 wt% or less in consideration of economy and mixability.

The mixed powder is molded at a molding pressure generally used in a sintering method (for example, 1 to 4 t / cm ² ) to obtain a molded body. This molded body is sintered in a non-oxidizing atmosphere (for example, in a hydrogen atmosphere or a vacuum atmosphere) at a temperature not higher than the melting point of Cu (1083 ° C.) to obtain a sintered body. In addition, the particle diameter of Mo powder shows the value measured by the Fisher method, and the average particle diameter of Cr powder shows the value measured by the laser diffraction type particle size distribution measuring apparatus. Moreover, when the upper limit of the particle | grains of a powder is defined, it shows that it is the powder classified by the sieve.

  A vacuum interrupter can be configured using the electrode material according to the embodiment of the present invention. As shown in FIG. 1, a vacuum interrupter 1 according to an embodiment of the present invention includes a vacuum vessel 2, a fixed electrode 3, and a movable electrode 4.

  The vacuum vessel 2 is configured by sealing both open end portions of the insulating cylinder 5 with a fixed side end plate 6 and a movable side end plate 7, respectively.

  The fixed electrode 3 is fixed in a state of passing through the fixed side end plate 6. One end of the fixed electrode 3 is fixed in the vacuum vessel 2 so as to face one end of the movable electrode 4, and an electrode material 8 is provided on the end of the fixed electrode 3 facing the movable electrode 4.

  The movable electrode 4 is provided on the movable side end plate 7. The movable electrode 4 is provided coaxially with the fixed electrode 3. The movable electrode 4 is moved in the axial direction by an opening / closing means (operation mechanism unit) (not shown), and the fixed electrode 3 and the movable electrode 4 are opened and closed. An electrode material 8 is provided at the end of the movable electrode 4 facing the fixed electrode 3. A bellows 9 is provided between the movable electrode 4 and the movable side end plate 7, and the movable electrode 4 is moved up and down while keeping the inside of the vacuum vessel 2 in a vacuum, so that the fixed electrode 3 and the movable electrode 4 can be opened and closed. Done.

[Examination of particle size distribution of Cr powder]
The electrode materials of Comparative Example 1-6 and Reference Example 1-5 were produced, and the voltage resistance and brazing properties of the electrode material due to the difference in the particle size distribution of Cr powder were examined. In the electrode material manufacturing methods of Comparative Examples, Reference Examples, and Examples which will be described in detail later, common Cu powder and Mo powder (average particle diameter of 3 μm) were used.

[Comparative Example 1]
The electrode material of Comparative Example 1 is a Cu—Cr-based electrode material that has been conventionally produced as an electrode material, and the Cr particle size and composition, molding pressure, sintering temperature, and sintering time are desired by each manufacturer. It is changed from the characteristic.

Cu powder and Cr powder having an average particle diameter of 80 μm (hereinafter referred to as Cr powder A) are mixed in a weight ratio so as to have a composition of Cu: Cr = 80: 20, and this mixed powder has an inner diameter of 50 mm. The mold was filled with 80 g and molded with a press pressure of 4 t / cm ² . The obtained molded body was fired at 1070 ° C. for 2 hours in a non-oxidizing atmosphere (in a vacuum of 5 × 10 ⁻⁵ Torr) to obtain a sintered body (electrode material) of Comparative Example 1.

  FIG. 2 is a diagram showing the results of measuring the particle size distribution of Cr powder A used in Comparative Example 1 with a laser diffraction particle size distribution measuring apparatus. In the Cr powder A, the volume relative particle amount (cumulative value) of particles having a particle diameter of 40 μm or less was 21%.

[Reference Example 1]
The weight ratio (wt%) of Cu powder, Cr powder with an average particle diameter of 80 μm (hereinafter referred to as Cr powder B), and Mo powder is Cu: Cr: Mo = 79: 20: 1. Then, 80 g of this mixed powder was filled in a mold having an inner diameter of 50 mm and molded with a press pressure of 4 t / cm ² . The obtained molded body was fired at 1070 ° C. for 2 hours in a non-oxidizing atmosphere (in a vacuum of 5 × 10 ⁻⁵ Torr) to obtain a sintered body (electrode material) of Reference Example 1.

  FIG. 3 is a diagram showing the results of measuring the particle size distribution of Cr powder B used in Reference Example 1 with a laser diffraction particle size distribution measuring apparatus. The Cr powder B is obtained by classifying the Cr powder A so that the volume relative particle amount with a particle diameter of 40 μm or less is less than 5%.

[Reference Example 2]
Cu powder, Cr powder B, and Mo powder are mixed in a weight ratio (wt%) so that the composition is Cu: Cr: Mo = 78: 19: 3, and this mixed powder has an inner diameter of 50 mm. The mold was filled with 80 g and molded with a press pressure of 4 t / cm ² . The obtained compact was fired at 1070 ° C. for 2 hours in a non-oxidizing atmosphere (in a vacuum of 5 × 10 ⁻⁵ Torr) to obtain a sintered body (electrode material) of Reference Example 2.

[Comparative Example 2]
Cu powder, Cr powder A, and Mo powder were mixed at a weight ratio (wt%) so that the composition of Cu: Cr: Mo = 79: 20: 1 was obtained, and the mixed powder had an inner diameter of 50 mm. The mold was filled with 80 g and molded with a press pressure of 4 t / cm ² . The obtained molded body was fired at 1045 ° C. for 2 hours in a non-oxidizing atmosphere (in a vacuum of 5 × 10 ⁻⁵ Torr) to obtain a sintered body (electrode material) of Comparative Example 2.

[Comparative Example 3]
Cu powder, Cr powder A, and Mo powder are mixed in a weight ratio (wt%) so that the composition is Cu: Cr: Mo = 78: 19: 3, and this mixed powder has an inner diameter of 50 mm. The mold was filled with 80 g and molded with a press pressure of 4 t / cm ² . The obtained molded body was fired at 1045 ° C. for 2 hours in a non-oxidizing atmosphere (in a vacuum of 5 × 10 ⁻⁵ Torr) to obtain a sintered body (electrode material) of Comparative Example 3.

[Comparative Example 4]
Cu powder, Cr powder A, and Mo powder are mixed in a weight ratio (wt%) so that the composition of Cu: Cr: Mo = 76: 19: 5 is obtained, and this mixed powder has an inner diameter of 50 mm. The mold was filled with 80 g and molded with a press pressure of 4 t / cm ² . The obtained molded body was fired at 1045 ° C. for 2 hours in a non-oxidizing atmosphere (in a vacuum of 5 × 10 ⁻⁵ Torr) to obtain a sintered body (electrode material) of Comparative Example 4.

[Comparative Example 5]
Cu powder, Cr powder A, and Mo powder are mixed in a weight ratio (wt%) so that the composition of Cu: Cr: Mo = 73: 18: 9 is obtained, and this mixed powder has an inner diameter of 50 mm. The mold was filled with 80 g and molded with a press pressure of 4 t / cm ² . The obtained compact was fired at 1045 ° C. for 2 hours in a non-oxidizing atmosphere (in a vacuum of 5 × 10 ⁻⁵ Torr) to obtain a sintered body (electrode material) of Comparative Example 5.

[Reference Example 3]
Cu powder, Cr powder B, and Mo powder are mixed in a weight ratio (wt%) so as to have a composition of Cu: Cr: Mo = 76: 19: 5, and this mixed powder has an inner diameter of 50 mm. The mold was filled with 80 g and molded with a press pressure of 4 t / cm ² . The obtained compact was fired at 1045 ° C. for 2 hours in a non-oxidizing atmosphere (in a vacuum of 5 × 10 ⁻⁵ Torr) to obtain a sintered body (electrode material) of Reference Example 3.

[Reference Example 4]
Cu powder, Cr powder B, and Mo powder are mixed in a weight ratio (wt%) so as to have a composition of Cu: Cr: Mo = 74: 19: 7, and this mixed powder has an inner diameter of 50 mm. The mold was filled with 80 g and molded with a press pressure of 4 t / cm ² . The obtained molded body was fired at 1045 ° C. for 2 hours in a non-oxidizing atmosphere (in a vacuum of 5 × 10 ⁻⁵ Torr) to obtain a sintered body (electrode material) of Reference Example 4.

[Reference Example 5]
Cu powder, Cr powder B, and Mo powder are mixed in a weight ratio (wt%) so as to have a composition of Cu: Cr: Mo = 76: 19: 5, and this mixed powder has an inner diameter of 50 mm. The mold was filled with 80 g and molded with a press pressure of 4 t / cm ² . The obtained compact was fired at 1030 ° C. for 2 hours in a non-oxidizing atmosphere (in a vacuum of 5 × 10 ⁻⁵ Torr) to obtain a sintered body (electrode material) of Reference Example 5.

[Comparative Example 6]
Cu powder, 100 mesh (aperture 150 μm) Cr powder, and Mo powder are mixed in a weight ratio (wt%) so that the composition is Cu: Cr: Mo = 80: 5: 15. 80 g of the mixed powder was filled in a mold having an inner diameter of 50 mm, and press-molded with a press pressure of ² t / cm ² . The filling factor of the molded body was 64%. The obtained molded body was fired at 1050 ° C. for 2 hours in a non-oxidizing atmosphere (in a vacuum of 5 × 10 ⁻⁵ Torr) to obtain a sintered body (electrode material) of Comparative Example 6. The filling factor of the sintered body of Comparative Example 6 is 73%, so that shrinkage due to sintering does not occur much, and it is considered that there are many pores inside the electrode material.

[Characteristic evaluation of electrode materials]
With respect to the sintered bodies of Reference Examples 1 to 5 and Comparative Examples 1 to 6, the filling rate (%), brazeability, and withstand voltage performance were measured. The filling factor was calculated by measuring the density of the sintered body and (measured density / theoretical density) × 100 (%). Brazing performance is achieved by placing a brazing material between the sintered body and the Cu electrode rod, and after vacuum brazing, performing a simple hammer impact method or performing a tensile test between the sintered body and the Cu electrode rod to increase the adhesion. evaluated. With respect to the withstand voltage performance, a vacuum interrupter was formed using a sintered body as an electrode, and a 50% flashover voltage was obtained by a lightning impulse flashover test (elevating method). In addition, withstand voltage performance is shown by the relative value when the sintered compact of the comparative example 1 is set to 1.0. Table 1 shows the measurement results of each sintered body.

  As shown in Table 1, the sintered bodies of Reference Examples 1 to 5 using Cr powder B had good brazing properties and improved withstand voltage compared to the sintered body of Comparative Example 1.

  Moreover, it turns out that the filling rate of a sintered compact falls, when the content rate of Mo increases, and the voltage endurance of a sintered compact rises, when the content rate of Mo increases. That is, in order to improve the voltage resistance of the electrode material, it is necessary to improve the Mo content. However, by increasing the Mo content, if the filling rate of the electrode material decreases, the electrode material is brazed. It becomes difficult to use as an electrode material.

  When comparing the sintered body of Reference Example 3 and the sintered body of Comparative Example 4, even if the Mo content is the same, by making the volume relative particle amount of fine Cr particles of 40 μm or less less than 5%, It can be seen that the filling factor of the sintered body is improved. This is because Cr having a particle size of 40 μm or less is considered to be easily diffused into Mo, and by making the amount of Cr particles in this range less than 10% (more preferably less than 5%), It is considered that the amount of Cr diffusion is suppressed, the voids in the sintered body are reduced, and the filling rate of the sintered body is improved. And it is thought that the improvement of the filling rate suppresses the infiltration of the brazing material into the sintered body and improves the brazing property.

  That is, the filling rate of the sintered body can be improved by adjusting the particle size distribution of the Cr powder mixed with the Mo powder. As a result, since the Mo content in the sintered body can be increased, the withstand voltage characteristics of the sintered body can be improved.

  In addition, when the reference examples 3 and 5 are compared, the filling factor of the sintered body changes depending on the sintering temperature. When the sintering temperature is 1045 ° C., the filling rate is the highest, and when the sintering temperature is lower than 1045 ° C., the filling rate is lowered, and even at a high temperature, the electrode material with a filling rate exceeding 90% has a small Mo content. Therefore, a significant improvement in withstand voltage performance cannot be expected. Therefore, the sintering temperature is 980 to 1080 ° C., more preferably 1070 to 1030 ° C., and still more preferably 1045 ° C., thereby obtaining a sintered body having a high filling rate and excellent brazing properties. be able to.

  Based on the knowledge of the above reference example, the inventors have completed the present invention. Hereinafter, although the specific example is given and the electrode material of this invention and the manufacturing method of an electrode material are demonstrated in detail, this invention is not limited to these Examples.

[Example 1]
Cu powder, Cr powder B, Mo powder, and Te powder (average particle diameter 45 μm) are in a weight ratio (wt%), Cu: Cr: Mo: Te = 76: 19: 5: 0.05 The mixture was mixed so as to have a composition, and 80 g of the mixed powder was filled in a mold having an inner diameter of 50 mm and molded with a press pressure of 4 t / cm ² . The obtained molded body was fired at 1058 ° C. for 2 hours in a non-oxidizing atmosphere (in a vacuum of 5 × 10 ⁻⁵ Torr) to obtain a sintered body (electrode material) of Example 1.

[Reference Example 6]
Cu powder, Cr powder B, and Mo powder are mixed in a weight ratio (wt%) so as to have a composition of Cu: Cr: Mo = 76: 19: 5, and this mixed powder has an inner diameter of 50 mm. The mold was filled with 80 g and molded with a press pressure of 4 t / cm ² . The obtained molded body was fired at 1058 ° C. for 2 hours in a non-oxidizing atmosphere (in a vacuum of 5 × 10 ⁻⁵ Torr) to obtain a sintered body (electrode material) of Reference Example 6.

[Reference Example 7]
Cu powder, Cr powder B, Mo powder, and Te powder (average particle diameter 45 μm) are in a weight ratio (wt%), Cu: Cr: Mo: Te = 74: 19: 7: 0.05 The mixture was mixed so as to have a composition, and 80 g of the mixed powder was filled in a mold having an inner diameter of 50 mm and molded with a press pressure of 4 t / cm ² . The obtained molded body was fired at 1058 ° C. for 2 hours in a non-oxidizing atmosphere (in a vacuum of 5 × 10 ⁻⁵ Torr) to obtain a sintered body (electrode material) of Reference Example 7.

[Reference Example 8]
Cu powder, Cr powder B, Mo powder, and Te powder (average particle diameter 45 μm) are in a weight ratio (wt%), Cu: Cr: Mo: Te = 73: 18: 9: 0.05 The mixture was mixed so as to have a composition, and 80 g of the mixed powder was filled in a mold having an inner diameter of 50 mm and molded with a press pressure of 4 t / cm ² . The obtained compact was fired at 1058 ° C. for 2 hours in a non-oxidizing atmosphere (in a vacuum of 5 × 10 ⁻⁵ Torr) to obtain a sintered body (electrode material) of Reference Example 8.

[Characteristic evaluation of electrode materials]
First, the cross section of the sintered body of Example 1 was observed with a microscope (reflection electron image).

  As shown in FIG. 4, the sintered body of Example 1 has a structure in which Cr particles 11 are dispersed in the Cu phase 10 and a Mo—Cr solid solution 12 is dispersed in the Cu phase 10. I understand.

  Next, with respect to the sintered bodies of Example 1 and Reference Examples 6 to 8, the filling rate, brazing property, withstand voltage performance, and welding force were measured. The weldability test was evaluated based on the force (kN) required for welding the electrodes by the STC test (25 kA-3 s) and peeling the electrodes apart. In addition, withstand voltage performance is shown by the relative value when the sintered body of Reference Example 6 is 1.0. Table 2 shows the measurement results of each sintered body. The weldability test was conducted by providing the movable electrode with the sintered body of Reference Example 6 and providing the fixed electrode with the sintered body to be measured (for example, the sintered body of Example 1). Therefore, since the weldability test could not be performed on the sintered body having reduced brazeability (that is, the sintered bodies of Reference Examples 7 and 8), measurement is impossible in Table 2. Moreover, the weldability test was performed twice with respect to each sample, and the average value is described. For example, the weldability test results and the measurement results of the weld area of the sintered body of Example 1 are as shown in Table 3.

  As shown in Table 2, the sintered bodies of Example 1 and Reference Example 6 are electrode materials having excellent brazing properties and excellent weldability. In particular, the sintered body of Example 1 has a voltage resistance equivalent to that of Reference Example 6, and the welding power is remarkably reduced. In the results shown in Table 1, the filling rate is 89% and the brazing property is Δ. This is because the brazing material used in the test of Table 1 is different from the brazing material used in the test of Table 2. Due to that. Further, when Te was added to the mixed powder in the range of 0.01 wt% to 0.2 wt%, the same effect as in Example 1 could be obtained. In addition, a decrease in the filling rate of the electrode material (that is, a decrease in brazing properties) was confirmed as the amount of Mo added increased. Therefore, the addition amount of Mo is in the range of 1% by weight or more and less than 7% by weight with respect to the mixed powder, whereby an electrode material excellent in brazing property, voltage resistance and welding resistance can be obtained. it is conceivable that.

[Effects of adding Te to electrode material]
The result of having tested the tensile strength with respect to the sintered compact of Example 1 and Reference Example 6-8 is shown in FIG.

  As shown in FIG. 5, it can be seen that the addition of Te significantly reduces the tensile strength of the sintered body (reduced to 1/2 or less). It is conceivable that the peeling force when the electrode material is welded is reduced due to the decrease in tensile strength. Therefore, it is considered that the welding resistance of the electrode material can be greatly improved by reducing the tensile strength by adding Te. In addition, since tensile strength is falling also by adding Mo, it is thought that the welding resistance of an electrode material can be improved by increasing the addition amount of Mo.

  According to the electrode material and the electrode material manufacturing method according to the embodiment of the present invention as described above, Cu powder, Cr powder, and refractory metal powder are mixed, and the obtained mixed powder is pressed. In the electrode material to be molded and sintered, Cr powder whose particle size is less than 10μm and whose volume relative particle amount is less than 10% is mixed with the mixed powder, so that it has excellent brazeability and voltage resistance. Can be obtained. Furthermore, by adding Te to the mixed powder in the range of 0.01 wt% or more and 0.2 wt% or less, it is possible to obtain an electrode material excellent in welding resistance while maintaining excellent voltage resistance characteristics. . The addition amount of Te is required to be an optimum addition amount in consideration of the effect of improving the welding resistance and the degree of decrease in the filling rate. For example, when Te is added in an amount greatly exceeding 0.2 wt%, Te is volatilized, the effect of improving the welding resistance is small, and there is a concern that the maintenance cost in the vacuum furnace increases. Moreover, the filling rate of the electrode material did not change so much when the amount of Te added was 0.01 wt% and 0.2 wt%.

  That is, in the method for producing an electrode material according to an embodiment of the present invention, Cr powder whose particle size has been adjusted in advance is mixed with mixed powder, the mixed powder is pressure-molded, and the molded body is sintered at a melting point of Cu or lower. By doing so, the filling rate after sintering becomes high, and an electrode material that can be brazed can be manufactured at a relatively low cost. Furthermore, an electrode material excellent in welding resistance can be manufactured at a relatively low cost by containing a small amount of Te which is a low melting point metal.

  In addition, according to the electrode material and the electrode material manufacturing method of the present invention, the filling rate after sintering is substantially 89% or more, and a solid solution of Cr and a refractory metal is dispersed in the Cu phase. An electrode material having a certain tissue can be obtained.

  In addition, according to the method for producing an electrode material of the present invention, a solid solution of a refractory metal (Cr, Mo, etc.) is uniformly dispersed in the Cu phase, and a dense electrode material having good withstand voltage performance is produced at low cost. Can do.

  For example, by providing the electrode material of the present invention on at least one of the fixed electrode and the movable electrode of the vacuum interrupter (VI), the voltage resistance of the electrode contact of the vacuum interrupter is improved. When the voltage resistance of the electrode contact is improved, the gap between the movable side electrode and the fixed side electrode at the time of opening and closing can be shortened and the gap between the electrode and the insulating cylinder can be further shortened than the conventional vacuum interrupter. The structure of the vacuum interrupter can be reduced. As a result, the vacuum interrupter can be reduced in size. By reducing the size of the vacuum interrupter components, the manufacturing cost of the vacuum interrupter can be reduced.

  Moreover, according to the electrode material and the vacuum interrupter of the present invention, a vacuum interrupter having excellent welding resistance can be obtained even when an electrode material containing Mo is used. For example, when Mo, which is a refractory metal, is added, there is a concern that the amount of heat generated during energization increases due to an increase in contact resistance, and the peeling force increases, but Te should be added. As a result, the welding resistance of the electrode material is improved, and the peeling force can be reduced. When the welding resistance of the electrode material is improved in this way, the operation mechanism unit when the electrodes are separated (during the opening / closing operation of the vacuum interrupter) can be reduced in size. As a result, the vacuum circuit breaker constituted by the vacuum interrupter and the operation mechanism unit can be greatly reduced in size.

DESCRIPTION OF SYMBOLS 1 ... Vacuum interrupter 2 ... Vacuum container 3 ... Fixed electrode 4 ... Movable electrode 5 ... Insulating cylinder 6 ... Fixed side end plate 7 ... Movable side end plate 8 ... Electrode material (electrode contact)
9 ... Bellows 10 ... Cu phase 11 ... Cr particles 12 ... Solid solution of Mo-Cr

Claims (6)

10 to 50% by weight of Cr powder with a particle diameter of 40 μm or less and a volume relative particle amount of less than 10%,
1% by weight to less than 7% by weight of refractory metal powder,
0.01 to 0.2% by weight of Te,
An electrode material characterized in that a mixture in which the balance is Cu powder and inevitable impurities is pressed and sintered. The refractory metal is at least one selected from Mo, W, Nb, Ta, V, Zr, Be, Hf, Ir, Pt, Ti, Si, Rh, and Ru. The electrode material according to claim 1. The electrode material according to claim 1 or 2, wherein a particle size of the refractory metal powder is 30 µm or less. 4. The electrode material according to claim 1, wherein an average particle diameter of the Cr powder is 150 μm or less. 5. 10 to 50% by weight of Cr powder having a particle size of 40 μm or less and a volume relative particle amount of less than 10%, refractory metal powder of 1 to 7% by weight, 0.01 to 0% A mixing step of mixing 2% by weight of Te and the remaining Cu powder;
A molding step of pressure-molding the mixture obtained in the mixing step;
A sintering step of sintering the molded body obtained in the molding step;
A method for producing an electrode material comprising: In the vacuum container, a vacuum interrupter provided with a fixed electrode and a movable electrode disposed so as to face and separate from the fixed electrode,
At least one of the fixed electrode and the movable electrode;
10 to 50% by weight of Cr powder with a particle diameter of 40 μm or less and a volume relative particle amount of less than 10%,
1% by weight to less than 7% by weight of refractory metal powder,
0.01 to 0.2% by weight of Te,
A vacuum interrupter characterized in that a mixture of which the remainder is Cu powder and inevitable impurities is sintered and formed after pressure molding.