JP2016211023A - Method of producing electrode material and electrode material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve withstand voltage performance of an electrode material.SOLUTION: A method of producing an electrode material containing Cu, Cr and heat resistant element is provided. A heat resistant element powder and a Cr powder are mixed at a rate of the heat resistant element<Cr by a weight ratio. A mixed powder of the heat resistant element powder and the Cr powder is burnt. A sintered body which is obtained by burning the mixed powder and contains a solid solution in which the heat resistant element and Cr are solid-solved is pulverized and a solid solution powder obtained by pulverization of the sintered body is classified in such a way that particle diameter is 200 μm or less. Classified solid solution powder of 10 to 60 pts.wt. and the Cu power of 90 to 40 pts.wt. are mixed and sintered to obtain the electrode material.SELECTED DRAWING: Figure 1

Description

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

  The contact material of the vacuum interrupter is (1) large breaking capacity, (2) high withstand voltage performance, (3) low contact resistance, (4) high welding resistance, (5) contact wear It is necessary to satisfy characteristics such as low amount, (6) low cutting current, (7) excellent workability, and (8) high mechanical strength.

  Since some of these characteristics are contradictory, there is no contact material that satisfies all of the above characteristics. Cu-Cr electrode materials are widely used as contact materials for vacuum interrupters because they have features such as a large breaking capacity, high withstand voltage performance, and high resistance to welding. Moreover, in the Cu-Cr electrode material, there exists a report that the one where the particle size of Cr particle | grains is fine is excellent in the surface of interruption | blocking current or contact resistance (for example, nonpatent literature 1).

  In recent years, usage conditions of consumers for vacuum interrupters have become stricter, and the application of vacuum interrupters to capacitor circuits has been expanding. In the capacitor circuit, since a voltage two to three times the normal voltage is applied between the electrodes, the contact surface is remarkably damaged by current interruption and arcing during current switching, and re-ignition is likely to occur. For this reason, there is an increasing demand for an electrode material having an interrupting performance and a withstand voltage performance superior to those of conventional Cu—Cr electrode materials.

  For example, in Patent Document 1, as a Cu—Cr-based electrode material having good electrical characteristics such as current interruption performance and withstand voltage performance, Cu used as a base material and Cr and Cr particles that improve electrical characteristics are finely divided. A method for producing an electrode material is described in which powders of heat-resistant elements (Mo, W, Nb, Ta, V, Zr) are mixed, and then the mixed powder is inserted into a mold and pressure-molded to form a fired body. Yes. Specifically, a heat-resistant element such as Mo, W, Nb, Ta, V, Zr is added to a Cu—Cr-based electrode material made of Cr having a particle size of 200 to 300 μm as a raw material, and Cr is formed through a microstructure technique. And promotes alloying of Cr element and heat-resistant element, increases precipitation of fine Cr-X (Cr in which heat-resistant element is dissolved) inside the Cu substrate structure, and has a diameter of 20 to 60 μm. Cr particles are uniformly dispersed in the Cu substrate structure in a form having a heat-resistant element therein. Patent Document 1 discloses that in an electrode material for a vacuum interrupter, in order to improve electrical characteristics such as current interruption performance and withstand voltage performance, Cr and heat-resistant elements in a Cu base material in a Cu-based electrode material are disclosed. It is described that it is important to increase the content and to make the particle size of Cr or the like finer and uniformly disperse.

  In Patent Document 2, a powder obtained by pulverizing a single solid solution that is a reaction product of a heat-resistant element without passing through a microstructure technique is mixed with Cu powder, pressure-molded, sintered, and an electrode. Manufactures electrode materials containing Cr and heat-resistant elements in the tissue.

JP 2002-180150 A Japanese Patent Laid-Open No. 4-334832 JP 2003-77375 A

Rieder, F. ua, “The Influence of Composition and Cr Particle Size of Cu / Cr Contacts on Chopping Current, Contact Resistance, and Breakdown Voltage in Vacuum Interrupters”, IEEE Transactions on Components, Hybrids, and Manufacturing Technology, Vol. 12, 1989, 273-283

  However, as described in Patent Document 2, when the ground arc-resistant metal (heat-resistant element and Cr element) powder and Cu powder are mixed, depending on the blending ratio of the heat-resistant element powder and Cr powder, the arc-resistant metal May agglomerate in the electrode structure and cause a decrease in withstand voltage performance and interruption performance.

  In addition, as described in Patent Document 3, even when the electrode material has the same composition, the blocking characteristics and conductivity of the electrode material differ depending on the particle size distribution of the Cr powder (and the heat-resistant element powder) mixed with the Cu powder. It will be.

  In view of the above circumstances, an object of the present invention is to provide a technique that contributes to improvement of withstand voltage performance among characteristics required for an electrode material.

  One aspect of the manufacturing method of the electrode material of the present invention that achieves the above object is to mix the heat-resistant element powder and the Cr powder in a ratio by weight ratio of heat-resistant element <Cr, and fire the mixed powder of the heat-resistant element powder and the Cr powder Then, the sintered body containing the solid solution in which the heat-resistant element and Cr are solid solution obtained by firing is pulverized, and the solid solution powder obtained by pulverization is classified so as to have a particle size of 200 μm or less. The solid solution powder 10-60 parts by weight and Cu powder 90-40 parts by weight are mixed and sintered.

  In another aspect of the method for producing an electrode material of the present invention that achieves the above object, in the method for producing an electrode material, the classified solid solution powder has a volume relative particle amount of particles having a particle diameter of 90 μm or less. It is characterized by being 90% or more.

  According to another aspect of the method for producing an electrode material of the present invention that achieves the above object, the median diameter of the heat-resistant element powder is 10 μm or less in the method for producing an electrode material.

  In another aspect of the method for producing an electrode material of the present invention that achieves the above object, in the method for producing an electrode material, the median diameter of the Cr powder is larger than the median diameter of the heat-resistant element powder, and is 80 μm or less. It is characterized by being.

  Another aspect of the method for producing an electrode material of the present invention that achieves the above object is characterized in that, in the method for producing an electrode material, the median diameter of the Cu powder is 100 μm or less.

  Another aspect of the method for producing an electrode material of the present invention that achieves the above object is characterized in that, in the method for producing an electrode material, the heat-resistant element is Mo.

  The electrode material of the present invention that achieves the above object is an electrode material containing 40 to 90% Cu, 5 to 48% Cr, and 2 to 30% heat-resistant element by weight ratio. Then, heat-resistant element powder and Cr powder are mixed at a weight ratio of heat-resistant element powder and Cr powder, the mixed powder of heat-resistant element powder and Cr powder is fired, and the heat-resistant element and Cr obtained by firing are in solid solution. The sintered body containing the solid solution was pulverized, the solid solution powder obtained by pulverization was classified so that the particle diameter was 200 μm or less, and the classified solid solution powder and Cu powder were mixed and sintered. It is a feature.

  In addition, a vacuum interrupter of the present invention that achieves the above object is characterized in that an electrode contact made of the above electrode material is provided on a movable electrode or a fixed electrode.

  According to the above invention, the withstand voltage performance of the electrode material is improved.

It is a figure which shows the flow of the manufacturing method of the electrode material which concerns on embodiment of this invention. It is a schematic sectional drawing of the vacuum interrupter which has the electrode material which concerns on embodiment of this invention. It is a figure which shows the flow of the manufacturing method of the electrode material which concerns on the comparative example 1. (A) Sectional micrograph of electrode material according to Comparative Example 1, (b) Sectional micrograph of electrode material according to Example 1, (c) Sectional micrograph of electrode material according to Comparative Example 3. It is a figure which shows the particle size distribution of the MoCr powder before classification and after classification. It is a microscope picture of MoCr powder near a particle size of 500 micrometers.

  A method for producing an electrode material and an electrode material according to an embodiment of the present invention will be described in detail with reference to the drawings. In the description of the embodiment, unless otherwise specified, the particle diameter (median diameter d50), average particle diameter, particle size distribution, volume relative particle amount, and the like are measured by a laser diffraction particle size distribution measuring apparatus (Cirrus Corporation: Cirrus 1090L). ) Indicates the value measured. Further, when the upper limit (or lower limit) of the particle diameter of the powder is determined, it indicates that the powder is classified by a sieve having an opening of the upper limit value (or lower limit value) of the particle diameter.

  The present invention relates to a composition control technique for a Cu—Cr—heat-resistant element (Mo, W, V, etc.) electrode material, and optimizes the grinding conditions (particle size distribution of refractory metal) of the MoCr reaction product. Accordingly, the withstand voltage performance is improved without impairing the filling rate and the conductivity as compared with the conventional electrode (Cu—Cr electrode). According to the electrode material of the present invention, it is possible to increase the breakdown voltage and capacity of the vacuum interrupter.

  Examples of the refractory elements include molybdenum (Mo), tungsten (W), tantalum (Ta), niobium (Nb), vanadium (V), zirconium (Zr), beryllium (Be), hafnium (Hf), and iridium (Ir). In addition, elements selected from elements such as platinum (Pt), titanium (Ti), silicon (Si), rhodium (Rh), and ruthenium (Ru) can be used alone or in combination. In particular, it is preferable to use Mo, W, Ta, Nb, V, or Zr, which has a remarkable effect of refining Cr particles. When the heat-resistant element is used as a powder, the median diameter d50 of the heat-resistant element powder is, for example, 10 μm or less, so that the particles containing the Cr (including the heat-resistant element and a solid solution of Cr) are uniformly refined. Can be dispersed. By including 2 to 30% by weight, more preferably 2 to 10% by weight, of the heat-resistant element with respect to the electrode material, the withstand voltage performance and current interruption performance of the electrode material are improved without impairing the mechanical strength and workability. Can be made. In the present invention, since classification is performed in the manufacturing process of the electrode material, the weight of the heat-resistant element (and Cr) in the electrode material cannot be accurately defined. However, the powder containing the heat-resistant element and Cr excluded in the classification process is 4% or less of the whole powder, and the amount of change in the mixing ratio of the heat-resistant element (and Cr) by classification is Cu, Cr, Mo When the blending ratio is less than ± 1%. Therefore, although the blending ratio of the heat-resistant element and Cr changes depending on the classification, it does not affect the electrode performance, and the weight of the heat-resistant element (and Cr) as the raw material can be regarded as the composition of the electrode material.

  Chromium (Cr) is included in the electrode material in an amount of 5 to 48% by weight, more preferably 5 to 16% by weight, so that the withstand voltage performance and current interruption performance of the electrode material are not impaired without impairing the mechanical strength and workability. Can be improved. When Cr powder is used, the median diameter d50 of the Cr powder is not particularly limited as long as it is larger than the median diameter of the heat-resistant element powder. For example, Cr powder having a median diameter of 80 μm or less is used.

  Copper (Cu) is contained in an amount of 40 to 90% by weight, more preferably 80 to 90% by weight with respect to the electrode material, thereby reducing the contact resistance of the electrode material without impairing the withstand voltage performance or the current interruption performance. be able to. By setting the median diameter d50 of the Cu powder to, for example, 100 μm or less, the heat-resistant element, the solid solution powder of Cr, and the Cu powder can be mixed uniformly. In the electrode material produced by the sintering method, the weight ratio of Cu can be arbitrarily set by adjusting the amount of Cu powder mixed with the solid solution powder of the heat-resistant element and Cr. Therefore, the total of the heat-resistant elements, Cr and Cu added to the electrode material does not exceed 100% by weight.

  A method for manufacturing an electrode material according to an embodiment of the present invention will be described in detail with reference to the flow of FIG. In the description of the embodiment, Mo will be described as an example, but the same applies to the case of using a powder of another heat-resistant element.

  In the Mo-Cr mixing step S1, heat-resistant element powder (for example, Mo powder) and Cr powder are mixed. The Mo powder and the Cr powder are mixed so that the weight of the Cr powder is larger than the weight of the Mo powder. For example, Mo powder and Cr powder are mixed within a range of Mo / Cr = 1/4 to 1/1 (not including Mo: Cr = 1: 1) by weight ratio.

  In the firing step S2, a mixed powder of Mo powder and Cr powder is fired. In the firing step S2, for example, the mixed powder compact is held in a vacuum atmosphere at a temperature of 900 to 1200 ° C. for 1 to 10 hours to obtain a MoCr sintered body. When the weight of the Cr powder in the mixed powder is larger than the weight of the Mo powder, Cr that does not form a solid solution with Mo remains after firing. Therefore, in the firing step S2, a porous body (MoCr sintered body) containing the MoCr alloy in which Cr is solid-phase diffused into Mo and the remaining Cr particles is obtained.

  In the pulverization / classification step S3, the MoCr sintered body obtained in the firing step S2 is pulverized with a ball mill or the like. The MoCr powder obtained by pulverizing the MoCr sintered body is classified by, for example, a sieve having an opening of 90 μm, and particles having a large particle diameter are removed. The pulverization time in the pulverization / classification step S3 is, for example, 2 hours per 1 kg of the MoCr sintered body. The average particle size of the pulverized MoCr powder varies depending on the blending ratio of the Mo powder and the Cr powder.

  In the Cu mixing step S4, the MoCr powder obtained in the pulverization / classification step S3 and the Cu powder are mixed.

  In the press forming step S5, the mixed powder obtained in the Cu mixing step S4 is formed. When a molded body is produced by press die molding, the molded body does not need to be processed after sintering, and can be used as an electrode (electrode contact material) as it is.

  In the main sintering step S6, the molded body obtained in the press molding step S5 is sintered to produce an electrode material. In the main sintering step S6, for example, the compact is sintered at a temperature not higher than the melting point of Cu (1083 ° C.) in a non-oxidizing atmosphere (such as a hydrogen atmosphere or a vacuum atmosphere).

  In addition, a vacuum interrupter can be comprised using the electrode material which concerns on embodiment of this invention. As shown in FIG. 2, a vacuum interrupter 1 having an electrode material according to an embodiment of the present invention includes a vacuum vessel 2, a fixed electrode 3, a movable electrode 4, and a main shield 10.

  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 so as to face one end of the movable electrode 4 in the vacuum vessel 2, and the end of the fixed electrode 3 facing the movable electrode 4 is in accordance with the embodiment of the present invention. An electrode contact material 8 which is an electrode material is provided.

  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 (not shown), and the fixed electrode 3 and the movable electrode 4 are opened and closed. An electrode contact 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.

  The main shield 10 is provided so as to cover a contact portion between the electrode contact material 8 of the fixed electrode 3 and the electrode contact material 8 of the movable electrode 4, and is insulated from an arc generated between the fixed electrode 3 and the movable electrode 4. Protect 5

[Comparative Example 1]
As an electrode material according to Comparative Example 1, a Cu—Cr electrode material was produced. The Cu—Cr electrode material was produced according to the flow shown in FIG. In the electrode material according to Comparative Example 1, thermite Cr powder having a median diameter of 80 μm or less and Cu powder having a median diameter of 100 μm or less were used.

  First, Cu powder and Cr powder were mixed at a weight ratio of Cu: Cr = 4: 1, and sufficiently mixed until uniform using a V-type mixer (step T1).

  After mixing, a compact was produced by press die molding (Step T2) and subjected to main sintering in a non-oxidizing atmosphere at 1070 ° C. for 2 hours to obtain an electrode material (Step T3).

  As shown in FIG. 4A, the electrode material according to Comparative Example 1 was an electrode material having a structure in which Cr particles were uniformly dispersed in the Cu phase. In addition, Table 1 shows various characteristics of the electrode material according to Comparative Example 1 (size distribution of arc-proof component, filling rate, Brinell hardness, conductivity, withstand voltage performance, dispersibility of arc-proof component). The particle size distribution of the arc-resistant component was measured with a laser diffraction particle size distribution measuring device (Cirrus: Cirrus 1090L), and the packing ratio was measured by measuring the density of the sintered body, (actual density / theoretical density) × 100 (% ). The withstand voltage performance was evaluated by measuring a 50% flashover voltage using each electrode material as an electrode (electrode contact material) of a vacuum interrupter. The withstand voltage performance of the examples (and the reference examples and other comparative examples) shows a relative value with the electrode material of the comparative example 1 as a reference (reference value 1.0). Further, the dispersibility of the arc resistant component was evaluated by observing an electron microscope image and the presence or absence of aggregated particles.

[Example 1]
The electrode material according to Example 1 was produced according to the flow shown in FIG. In the electrode material according to Example 1, Mo powder having a median diameter of 10 μm or less, Thermite Cr powder having a median diameter of 80 μm or less, and Cu powder having a median diameter of 100 μm or less were used. In addition, the electrode material which concerns on another Example, the reference example, and the comparative example produced the electrode material using the same raw material.

  First, Mo powder and Cr powder were mixed at a weight ratio of Mo: Cr = 1: 4 and mixed uniformly using a V-type mixer.

  After the completion of mixing, this mixed powder of Mo powder and Cr powder was transferred into an alumina container and heat-treated at 1150 ° C. for 6 hours in a non-oxidizing atmosphere. The obtained porous product, which is the reaction product, was pulverized and classified with a sieve having an opening of 90 μm to obtain MoCr powder. As shown in FIG. 5, by classifying the pulverized MoCr powder, the volume relative particle amount (integrated value) of particles having a particle diameter of 90 μm or less was 94%.

  Next, the Cu powder and the classified MoCr powder are uniformly mixed at a weight ratio of Cu: MoCr = 4: 1, and a compact is produced by press die molding, and 1070 ° C. for 2 hours. An electrode material was obtained by sintering in a non-oxidizing atmosphere.

  As shown in FIG.4 (b), the electrode material which concerns on Example 1 is uniform, without the fine MoCr particle | grains alloyed with Cr which remained in the baking process of the Mo-Cr mixed powder aggregating in Cu phase. It was dispersed.

  Table 1 shows various characteristics of the electrode material according to Example 1. As shown in Table 1, the electrode material according to Example 1 has an electrode hardness of 19% higher than that of Comparative Example 1, and a withstand voltage performance when incorporated in a vacuum interrupter is increased by 30%. .

[Example 2]
The electrode material according to Example 2 is an electrode material manufactured by the same method as the electrode material according to Example 1 except that the mixing ratio of Mo powder and Cr powder in the Mo—Cr mixing step S1 is different.

  Mo powder and Cr powder were mixed at a weight ratio of Mo: Cr = 2: 3, and an electrode material was produced according to the flow shown in FIG.

  When the electrode material according to Example 2 was observed with an electron microscope, no aggregation of MoCr and Cr was observed in the electrode structure, and the electrode material had a structure in which MoCr particles and Cr particles were uniformly dispersed.

  Table 1 shows various characteristics of the electrode material according to Example 2. As shown in Table 1, the electrode material according to Example 2 has a withstand voltage equal to or higher than that of the electrode material of Comparative Example 1 because the electrode hardness is increased by 9% as compared with the electrode material of Comparative Example 1. It is considered to have performance.

[Reference Example 1]
The electrode material according to Reference Example 1 is an electrode material produced by the same method as the electrode material according to Example 1 except that the mixing ratio of Mo powder and Cr powder in the Mo—Cr mixing step S1 is different.

  Mo powder and Cr powder were mixed at a weight ratio of Mo: Cr = 1: 1, and an electrode material was produced according to the flow shown in FIG.

  When the electrode material according to Reference Example 1 was observed with an electron microscope, no aggregation of MoCr and Cr was observed in the electrode structure, and the electrode material had a structure in which MoCr particles and Cr particles were uniformly dispersed.

  Table 1 shows various characteristics of the electrode material according to Reference Example 1. As shown in Table 1, since the electrode material according to Reference Example 1 has the same electrode hardness as that of the electrode material of Comparative Example 1, it has a withstand voltage equivalent to that of the electrode material of Comparative Example 1. It is considered to have performance.

[Comparative Example 2]
The electrode material according to Comparative Example 2 is an electrode material produced by the same method as the electrode material according to Example 1 except that the mixing ratio of Mo powder and Cr powder in the Mo—Cr mixing step S1 is different.

  Mo powder and Cr powder were mixed at a weight ratio of Mo: Cr = 3: 2, and an electrode material was produced according to the flow shown in FIG.

  When the electrode material according to Comparative Example 2 was observed with an electron microscope, a MoCr aggregate of about 500 μm was confirmed in the electrode structure.

  Table 1 shows various characteristics of the electrode material according to Comparative Example 2. As shown in Table 1, the filling rate of the electrode material according to Comparative Example 2 was 12% lower than that of the electrode material of Comparative Example 1. When the filling rate of the electrode material is reduced, when the electrode material is used as an electrode contact material, the brazing material is sucked into the electrode material, which causes a decrease in the brazing property of the electrode material. Further, the electrode material according to Comparative Example 2 is considered to have a lower withstand voltage performance than the electrode material of Comparative Example 1 because the electrode hardness is lower than that of the electrode material of Comparative Example 1.

[Comparative Example 3]
The electrode material according to Comparative Example 3 is an electrode material produced by the same method as the electrode material according to Example 1 except that the mixing ratio of Mo powder and Cr powder in the Mo—Cr mixing step S1 is different.

  Mo powder and Cr powder were mixed at a weight ratio of Mo: Cr = 9: 1, and an electrode material was produced according to the flow shown in FIG.

  As shown in FIG.4 (c), when the electrode material which concerns on the comparative example 3 was observed with the electron microscope, about 500 micrometers MoCr aggregate was confirmed in the electrode structure | tissue.

  Table 1 shows various characteristics of the electrode material according to Comparative Example 3. As shown in Table 1, the filling rate of the electrode material according to Comparative Example 3 was 10% lower than that of the electrode material of Comparative Example 1. Therefore, like the electrode material of Comparative Example 2, it is considered that the brazing property of the electrode material according to Comparative Example 3 also decreases. Further, the electrode material according to Comparative Example 3 is considered to have a lower withstand voltage performance than the electrode material of Comparative Example 1 because the electrode hardness is lower than that of the electrode material of Comparative Example 1.

[Example 3]
The electrode material according to Example 3 is an electrode material produced by the same method as in Example 1 except that the mixing ratio of Cu powder and MoCr powder in Cu mixing step S4 is different.

  In the electrode material according to Example 3, the powder obtained by pulverization (and classification) in the pulverization / classification step S3 in the Cu mixing step S4 of the flow shown in FIG. 1 is Cu: MoCr = 17: The mixture was uniformly mixed at a ratio of 3. And the molded object was produced by press die shaping | molding, and main sintering was carried out in non-oxidizing atmosphere at 1070 degreeC-2 hours.

  When the electrode material according to Example 3 was observed with an electron microscope, MoCr particles and aggregates of Cr particles were not confirmed, and the electrode material had a uniformly dispersed structure.

  Table 1 shows various characteristics of the electrode material according to Example 3. As shown in Table 1, the electrode material according to Example 3 improved the electrode hardness and conductivity by about 15% as compared with the electrode material of Comparative Example 1. Therefore, the electrode material according to Example 3 is considered to be an electrode material having high withstand voltage performance and capable of reducing the contact resistance of the vacuum interrupter.

[Example 4]
The electrode material according to Example 4 is an electrode material produced by the same method as in Example 1 except that the mixing ratio of Cu powder and MoCr powder in Cu mixing step S4 is different.

  In the electrode material according to Example 4, in the Cu mixing step S4 of the flow shown in FIG. 1, the powder pulverized (and classified) in the pulverization / classification step S3 is Cu: MoCr = 9: The mixture was uniformly mixed at a ratio of 1. And the molded object was produced by press die shaping | molding, and main sintering was carried out in non-oxidizing atmosphere at 1070 degreeC-2 hours.

  When the electrode material according to Example 4 was observed with an electron microscope, MoCr particles and aggregates of Cr particles were not confirmed, and the electrode material had a uniformly dispersed structure.

  Table 1 shows the characteristics of the electrode material according to Example 4. As shown in Table 1, the conductivity of the electrode material according to Example 4 was improved by 26% as compared with the electrode material of Comparative Example 1. Further, the electrode material according to Example 4 has a slightly improved electrode hardness as compared with the electrode material of Comparative Example 1, and has a withstand voltage performance equal to or higher than that of the electrode material of Comparative Example 1. it is conceivable that.

  According to the method for producing an electrode material of the present invention as described above, an electrode material excellent in conductivity and withstand voltage performance can be obtained by mixing Mo powder and Cr powder so that Mo <Cr by weight ratio. Can be obtained.

  That is, as shown in Patent Document 3, even if the electrode material has the same composition, the characteristics of the electrode material differ depending on the particle size distribution of arc-resistant metal (MoCr solid solution or Cr) dispersed in the electrode material. . Therefore, in the method for producing an electrode material according to the present invention, a MoCr solid solution in which Cr remains is produced by firing a mixed powder of Mo powder and Cr powder mixed so that Mo <Cr by weight ratio. By crushing the obtained solid solution, an arc resistant metal (particle group near particle size x1) mainly composed of MoCr and an arc resistant metal (particle group near particle size x2) mainly composed of residual Cr, Arc resistant metals having different particle sizes can be easily adjusted. As a result, an electrode material having a structure in which the arc-resistant metal is uniformly dispersed without forming an aggregate in the electrode structure, and having excellent conductivity or withstand voltage performance as compared with conventional electrode materials is manufactured. Can do.

  For example, as shown in FIG. 5, in the electrode material of Example 1, the MoCr powder obtained in the pulverization / classification step S3 has a particle size distribution having a maximum value (mode) at x1 = 13 μm and x2 = 66 μm. It has become. When this powder was analyzed by X-ray diffraction, it was confirmed that Cr was present. Thus, it can be seen that the particle group in the vicinity of the particle size x1 is a particle group mainly composed of a solid solution of MoCr, and the particle group in the vicinity of the particle size x2 is a particle group mainly composed of the remaining Cr.

  As shown in FIG. 6, the particle size distribution of the MoCr powder before classification has a maximum value in the vicinity of the particle size x3 = 500 μm. The particle group in the vicinity of the particle size x3 is considered to be a particle group mainly composed of scaly MoCr (Cr), and causes deterioration of press formability, withstand voltage performance, interruption performance, and welding resistance. It is considered to be.

  Therefore, in the method for producing an electrode material according to the present invention, scaly MoCr (Cr) particles are removed by classification after pulverization. In this way, the MoCr powder to be mixed with the Cu powder is adjusted so that the particle size is 200 μm or less, more preferably, the volume relative particle amount of particles having a particle size of 90 μm or less is adjusted to be 90% or more. Thus, characteristics such as conductivity and withstand voltage performance of the electrode material are improved.

  In addition, in the electrode materials of Comparative Examples 2 and 3, although the MoCr powder mixed with the Cu powder uses a powder classified in advance to 90 μm or less, an aggregate of about 500 μm is confirmed in the electrode structure. Yes. Such a high melting point metal (Cr, Mo, MoCr solid solution) that exists in an aggregated state without being dispersed in the electrode structure causes a decrease in voltage resistance and welding resistance.

  On the other hand, in the manufacturing method of the electrode material which concerns on this invention, the weight ratio of Mo powder and Cr powder mixed by Mo-Cr mixing process S1 is Mo <Cr, and in this sintering process S6 Generation | occurrence | production of the aggregate of a MoCr solid solution and residual Cr is suppressed, and the electroconductivity and / or withstand voltage characteristic of an electrode material are improved. In addition, although the withstand voltage property of an electrode material does not change so much with the mixing ratio of Mo powder and Cr powder contained in an electrode material, it is known that welding resistance differs. Therefore, by setting the mixing ratio of the Mo powder and the Cr powder to Mo <Cr by weight, an electrode material having excellent welding resistance can be manufactured compared to the case of Mo> Cr.

  Further, by optimizing the particle size distribution of the MoCr powder and setting the weight ratio of the Cu powder to the electrode material to 80% to 90%, more preferably 85% to 90%, the hardness and conductivity of the electrode material Can be improved. As a result, it is possible to increase the breakdown voltage and capacity of the vacuum interrupter.

  For example, by setting the median diameter of the heat-resistant element (for example, Mo) powder to 10 μm or less and the median diameter of the Cr powder to 80 μm or less, the particle size distribution of the powder obtained by the firing step S2 and the pulverization / classification step s3 is at least A MoCr powder having a maximum value at two points of particle size x1 (x1 = 8 μm to 15 μm) and particle size x2 (x2 = 56 μm to 70 μm) can be obtained. Furthermore, by mixing Mo powder and Cr powder at a weight ratio of Mo <Cr, the frequency y1 of the particle size x1 and the frequency y2 of the particle size x2 satisfy at least y1 / y2 <1.6. It will be. The mixed powder of Cu powder and MoCr powder is sintered by adjusting the particle size distribution (and grinding conditions, grinding method, etc.) of the MoCr powder mixed with the Cu powder so that y1 / y2 <1.6. Thus, when obtaining an electrode material, the generation of MoCr (Cr) aggregates is suppressed.

  As described above, the preferred embodiments of the present invention have been described in the description of the embodiments. However, the electrode material manufacturing method and the electrode materials of the present invention are not limited to the embodiments and do not impair the features of the invention. The design can be changed as appropriate, and the changed design also belongs to the technical scope of the present invention.

  Further, 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), for example, the withstand voltage performance of the electrode contact of the vacuum interrupter is improved. When the withstand voltage performance of electrode contacts is improved, the gap between the movable and fixed electrodes can be shortened and the gap between the electrode and the insulating cylinder can be shortened compared to the conventional vacuum interrupter. Therefore, the structure of the vacuum interrupter can be reduced.

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 ... Main shield

Claims (8)

Heat-resistant element powder and Cr powder are mixed in a ratio of heat-resistant element <Cr by weight ratio,
Firing mixed powder of heat-resistant element powder and Cr powder,
Pulverizing a sintered body obtained by firing and containing a solid solution in which a heat-resistant element and Cr are dissolved,
The solid solution powder obtained by pulverization is classified so that the particle diameter is 200 μm or less,
A method for producing an electrode material, comprising mixing and sintering 10 to 60 parts by weight of classified solid solution powder and 90 to 40 parts by weight of Cu powder. 2. The method for producing an electrode material according to claim 1, wherein the classified solid solution powder has a volume relative particle amount of particles having a particle diameter of 90 μm or less of 90% or more. The method for producing an electrode material according to claim 1 or 2, wherein the median diameter of the heat-resistant element powder is 10 µm or less. 4. The method for producing an electrode material according to claim 1, wherein a median diameter of the Cr powder is larger than a median diameter of the heat-resistant element powder and is 80 μm or less. 5. The method for producing an electrode material according to any one of claims 1 to 4, wherein a median diameter of the Cu powder is 100 µm or less. The said heat-resistant element is Mo, The manufacturing method of the electrode material of any one of Claims 1-5 characterized by the above-mentioned. An electrode material containing, by weight, 40 to 90% Cu, 5 to 48% Cr, and 2 to 30% heat-resistant element,
Heat-resistant element powder and Cr powder are mixed in a ratio of heat-resistant element <Cr by weight ratio,
Firing mixed powder of heat-resistant element powder and Cr powder,
Pulverizing a sintered body obtained by firing and containing a solid solution in which a heat-resistant element and Cr are dissolved,
The solid solution powder obtained by pulverization is classified so that the particle diameter is 200 μm or less,
An electrode material obtained by mixing and sintering a classified solid solution powder and Cu powder. A vacuum interrupter comprising an electrode contact made of the electrode material according to claim 7 on a movable electrode or a fixed electrode.