JP2008171682A - Manufacturing method of contact material, and manufacturing method of vacuum valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a contact material capable of manufacturing the contact material, having cutting performance, breaking performance, and power transmission characteristics by reducing the loss of a raw material. <P>SOLUTION: The manufacturing method of a contact material includes: a process (S1) for obtaining mixed powder by mixing a conductive constituent made of silver having 30-50 wt.%, an arc-proof constituent made of tungsten carbide having 48.5-68.5 wt.%; and an auxiliary constituent made of at least one of cobalt, iron, and nickel having 0.2-5 wt.%; a process (S2) for obtaining a forming body by forming the mixed powder so that a void ratio becomes 25-35%; a process (S3) for obtaining a heat treatment body by heat-treating the forming body at 1,150-1,250°C in a reducing atmosphere; and a process (S4) for obtaining a pressurized body by pressurizing the heat treatment body so that the void ratio becomes not more than 10%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a contact material and a method for manufacturing a vacuum valve.

  As a contact material for a vacuum valve containing tungsten carbide (WC) having low cutting properties, it is known that an Ag-WC contact has excellent characteristics. There are two types of manufacturing methods for Ag-WC-based contact materials: an infiltration method and a sintering method.

  The infiltration method is a manufacturing method in which a conductive component is infiltrated into a void of a sintered compact obtained by pre-sintering a powder compact mainly composed of an arc-proof component. The Ag-WC contact material described in Patent Document 1 is manufactured by this method. The infiltration method is a method in which conductive components are infiltrated into the voids of the arc-resistant component skeleton sintered body by the balance between gravity and capillary force, so it is necessary to infiltrate more conductive components than the amount that just fills the skeleton voids. Don't be. Further, since there is a portion where the void is not completely filled in the vicinity of the surface of the infiltrant, the surface of the infiltrant must be cut and removed from the surface that can ensure soundness to a certain depth. As described above, the infiltration method has a problem that the amount of raw material loss is large.

  On the other hand, the sintering method is a production method in which a compact of a mixed powder composed of a conductive component, an arc-proof component and, if necessary, an auxiliary component is sintered at a high temperature. The Ag—Cu—WC contact material described in Patent Document 2 is manufactured by this method. Since the sintering method can easily reduce the loss of the raw material by forming the shape close to the final shape, there is a problem in removing oxides and adsorbed oxygen on the surface of the raw material. This is because, in the sintering method, it is generally necessary to increase the relative density at the time of molding, so the remaining voids become a closed space, and the oxide or oxygen trapped inside this cannot be reduced and removed. is there. In particular, in Ag-WC that requires low cutting characteristics, the WC powder and Ag powder of the raw material must be fine particles in order to homogenize the contact material, and the oxide and adsorbed oxygen on the surface of the raw material are extremely large. In the sintering method, the amount of oxygen is reduced by sintering in a hydrogen atmosphere. However, in the sintering method, even if hydrogen can penetrate into the enclosed space, if it reacts with oxygen and becomes water vapor, it is impossible to get out of the material from the enclosed space, and the oxygen content becomes high. . Therefore, the contact material manufactured by the sintering method does not provide the high breaking performance as the contact material manufactured by the infiltration method. In addition, when sintered as a low-density molded body, the density after sintering is insufficient, so the inside of the contact material once reduced is re-oxidized before proceeding to the pressurization step, and re-added. Oxygen is confined in the closed space during pressure, and high shut-off performance cannot be obtained.

As described above, in the conventional infiltration method and sintering method, it has been difficult to produce a contact material having excellent low cutting performance and interruption performance while reducing the loss of raw materials.
Japanese Patent Application No. 6-3347 JP 2006-120373 A

  The present invention provides a method for producing a contact material and a method for producing a vacuum valve, which can produce a contact material having both excellent cutting performance and interruption performance with reduced loss of raw materials.

  According to one aspect of the present invention, (i) a conductive component composed of 30 to 50% by weight of silver, an arc resistant component composed of 48.5 to 68.5% by weight of tungsten carbide, and 0.2 to 5% by weight. And (b) forming the mixed powder so that the porosity is 25 to 35%, and forming a molded body. (C) a step of obtaining a heat-treated body by heat-treating the molded body at 1150 to 1250 ° C. in a reducing atmosphere, and (d) pressurizing the heat-treated body so that the porosity is 10% or less. A method for producing a contact material including a step of obtaining a pressurizing body is provided.

  According to another aspect of the present invention, (a) an arc resistance composed of a conductive component composed of 5 to 25% by weight of silver and 25 to 35% by weight of copper, and 48.5 to 68.5% by weight of tungsten carbide. A step of mixing a component and an auxiliary component comprising at least one of 0.2 to 5% by weight of cobalt, iron, and nickel to obtain a mixed powder; and (b) a porosity of 25 to 35% of the mixed powder. (C) a step of obtaining a heat-treated body by heat-treating the formed body at 1150 to 1250 ° C. in a reducing atmosphere, and (d) a porosity of 10 The method of manufacturing a contact material including the step of pressurizing to be equal to or less than% is provided.

  According to still another aspect of the present invention, (b) 48.5 to 68.5% by weight of a conductive component comprising 30 to 50% by weight of silver and 10% by weight or less of carbide other than tungsten carbide. Mixing a raw material powder composed of an arc-proofing component made of carbide and an auxiliary component made of at least one of 0.2 to 5% by weight of cobalt, iron, and nickel to obtain a mixed powder; And (c) a step of obtaining a heat-treated body by heat-treating the formed body at 1150 to 1250 ° C. in a reducing atmosphere. And (d) a method of manufacturing a contact material including a step of pressing the heat-treated body so that the porosity is 10% or less to obtain a pressed body.

  According to still another aspect of the present invention, (a) a conductive component composed of 30 to 50% by weight of silver, an arc resistant component composed of 48.5 to 68.5% by weight of tungsten carbide, and 0.2 to A step of mixing 5% by weight of an auxiliary component composed of at least one of cobalt, iron, and nickel to obtain a mixed powder, and forming the mixed powder to have a porosity of 25 to 35% to obtain a molded body A step of producing a contact material by a step of heat-treating the molded body in a reducing atmosphere at 1150 to 1250 ° C. to obtain a heat-treated body and a step of pressurizing the heat-treated body so that the porosity is 10% or less; And (b) a step of bonding the contact material to each of the pair of electrodes at 800 to 950 ° C.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the contact material which can manufacture the contact material which has the outstanding cutting performance and interruption | blocking performance by reducing the loss of a raw material, and the manufacturing method of a vacuum valve can be provided.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  Further, the embodiments described below exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention includes the material, shape, structure, The layout is not specified as follows. The technical idea of the present invention can be variously modified within the scope of the claims.

  FIG. 1 shows a partial cross-sectional view of a vacuum valve according to an embodiment of the present invention. In FIG. 1, the blocking chamber 1 includes an insulating container 2 formed in a substantially cylindrical shape by an insulating material, and metal lids 4a and 4b provided on both ends of the insulating container 2 via sealing fittings 3a and 3b. It is constructed in a vacuum-tight manner. In the blocking chamber 1, a pair of electrodes 7 and 8 attached to opposite ends of the conductive rods 5 and 6 are disposed. The upper electrode 7 is a fixed electrode and the lower electrode 8 is a movable electrode. A bellows 9 is attached to the electrode rod 6 of the electrode 8 so that the electrode 8 can be moved in the axial direction while keeping the inside of the shut-off chamber 1 vacuum-tight. A metal arc shield 10 is provided on the bellows 9. The arc shield 10 prevents the bellows 9 from being covered with arc vapor. A metal arc shield 11 is provided in the blocking chamber 1 so as to cover the electrodes 7 and 8. The arc shield 11 prevents the insulating container 2 from being covered with arc vapor.

  As shown in FIG. 2, the electrode 8 is fixed to the conductive rod 6 by brazing with a brazing material 12, or is crimped and connected by caulking. The contact 13 b is attached to the electrode 8 by brazing with a brazing material 14. The contact 13a shown in FIG. 1 is attached to the electrode 7 by brazing.

  Next, an example of a method for manufacturing a contact material and a method for manufacturing a vacuum valve using the contact material according to the embodiment of the present invention will be described with reference to the flowchart of FIG.

  In step S1, a conductive component composed of about 30 to 50% by weight (hereinafter referred to as “wt%”) of Ag, an arc resistant component composed of about 48.5 to 68.5% by weight WC, and 0.2 to A raw powder composed of an auxiliary component made of at least one of cobalt (Co), iron (Fe), and nickel (Ni) of about 5 wt% is mixed to obtain a mixed powder. As an auxiliary component, any two or more of Co, Fe, and Ni may be combined and mixed.

  In step S2, the mixed powder is molded so that the porosity is about 25 to 35% to obtain a molded body.

  In step S3, the compact is subjected to a reduction heat treatment at about 1150 to 1250 ° C. in a reducing atmosphere. Here, in Step S1, auxiliary components such as Co, Fe, and Ni are mixed at about 0.2 to 5 wt%, so that the auxiliary components such as Co are diffused to the surface of the molded body during the reduction heat treatment in Step S3. The accompanying oxygen removal action can reduce the amount of oxygen on the surface of the molded body. Furthermore, since the porosity of the molded body is set to a range of about 25 to 35% in step S2, the formation of closed voids during the reduction heat treatment in step S3 is suppressed, and the surface of the molded body in which the reducing gas includes the surface of the void portion. The oxide can be sufficiently reduced and removed in contact with the substrate. Furthermore, in Step S3, the heat treatment temperature is set to about 1150 to 1250 ° C. which is equal to or higher than the melting point of Ag (961 ° C.), so that oxygen or oxide on the Ag surface can be removed. Furthermore, since the auxiliary component such as Co is added and heat-treated, the sintering can be rapidly advanced, and once the reduction heat treatment is completed, the voids inside the molded body once reduced can be completely closed. Therefore, it is possible to suppress the inside of the contact material from being re-oxidized by the outside air until it proceeds to the next step after taking out or in the next step.

  In step S4, the heat treatment body is re-pressurized to increase the density so that the porosity is about 10% or less to obtain a pressure body. Note that the densification can be further promoted by the shrinkage effect by adding auxiliary components such as Co after the heat treatment in step S3.

  In step S5, if necessary, the pressure body is heat-treated at a temperature of about 800 to 1250 ° C. to obtain a reheat-treated body. In the case where high electrical conductivity is also required, the electrical conductivity is reduced by repressurization in step S4, but the electrical conductivity can be sufficiently recovered by this reheat treatment step, and the interruption performance can be improved. Thereafter, the reheated body is processed into a predetermined shape to complete a vacuum valve contact material.

  When a vacuum valve is manufactured using this vacuum valve contact material, in step S6, the vacuum valve contact material is used for the contacts 13a and 13b shown in FIG. 1, and the contacts 13a and 13b and the electrodes 7 and 8 are connected. Each is joined by brazing to assemble a vacuum valve. At this time, if necessary, the electrical conductivity can be recovered by heat-treating the pressure body at a temperature of about 800 to 1250 ° C.

  As described above, according to the vacuum valve contact material and the vacuum valve manufacturing method according to the embodiment of the present invention, a contact material having excellent breaking performance and cutting characteristics and a vacuum valve using the contact material are realized. It becomes possible.

  Samples (Examples 1 to 32 and Comparative Examples 1 to 18) were prepared and evaluated using the method for manufacturing a contact material according to the embodiment of the present invention. A standard process is set for evaluation. In step S1 shown in FIG. 3, WC having an average particle diameter of 2.5 μm, 2 μm Ag powder, and 5 μm Co powder are mixed. The mixing ratio of Ag, WC and Co is 40: 58.5: 1.5 in volume%. In step S2, the mixed powder is molded so as to have a porosity of 30% to obtain a molded body. In step S3, the molded body is heat-treated at 1200 ° C. for 2 hours in a hydrogen atmosphere to obtain a heat-treated body (sintered body). In step S4, the sintered body is re-pressurized so as to reduce the porosity to 7% to obtain a pressurized body. In step S5, the contact material is manufactured by re-heating the pressure body at 850 ° C. In step S6, the contact material was processed into a predetermined shape and then joined to the electrode at 850 ° C. The manufacturing process of the contact material and the joining process of the contact material and the electrode were regarded as “standard process”, and the characteristics when a specific parameter was changed from the standard process were examined.

  Next, the evaluation method and evaluation conditions of the samples (Examples 1 to 32 and Comparative Examples 1 to 18) will be described. As an evaluation method, material property evaluation and electrical property evaluation are performed. In the material property evaluation, evaluation is made by porosity, oxygen content and electrical conductivity. “Porosity” was determined by measuring the density by dimensional measurement, obtaining the true density from the composition ratio, converting it to the relative density, and taking the value of the relative density as the remaining value subtracted from 100%. The “oxygen content” was determined by infrared absorption method after cutting out small pieces of analytical samples from the prototype material. The “conductivity” was obtained by measuring 10 points on the surface of the prototype material by an eddy current measurement method and calculating the average value.

  On the other hand, in the electrical property evaluation, the interruption characteristic and the cutting characteristic are evaluated. As the breaking characteristics, the prototype contact material was mounted on a vacuum valve, the breaking performance was evaluated by a synthetic breaking test, and the maximum breaking current value of the vacuum valve used was measured. Evaluation was performed 3 times under the condition of 12.5 kA with an applied voltage of 7.2 kV and an electrode of φ40 mm, the average value of each time was obtained, and shown as a relative value with Example 2 manufactured in the standard process, An excess of 0.9 was determined to be good. As the cutting characteristics, the cutting current value was measured 500 times at 70 Arms with a resistance load circuit, and the average value was obtained. The evaluation result was displayed as a relative value with respect to Example 2, and less than 1.5 was determined to be good.

(Examples 1-3 and Comparative Examples 1 and 2)
FIG. 4 shows the results of trial production of contact materials of Examples 1 to 3 and Comparative Examples 1 and 2 in which the Ag content in the raw material mixing step was changed within a range of 25 to 55 wt%, and the evaluation was carried out by mounting on a vacuum valve. Indicates. In each of Examples 1 to 3 and Comparative Examples 1 and 2, the porosity of the molded body was set to 30%, oxygen was reduced on the powder surface using this void, and Co was added and heat treated at 1200 ° C. By doing so, the above-mentioned voids are closed, and reoxidation by outside air after taking out is suppressed, so that a low oxygen content of 100 ppm or less can be achieved. Further pressurization increases the conductivity by setting the porosity to 7%. Here, in Examples 1 to 3 in which the Ag content is in the range of 30 to 50 wt%, since the Ag and WC component amounts are appropriate, both the blocking performance and the cutting characteristics are good. On the other hand, in Comparative Example 1 where the Ag content is 25 wt%, which is less than the range of Examples 1 to 3, the electrical conductivity is too low, so that a sufficient blocking performance is not obtained. On the other hand, in Comparative Example 2 in which the Ag content is 55 wt%, which is larger than the range of Examples 1 to 3, the cutting characteristics are insufficient because there are too few WCs having an effect of reducing the cutting characteristics.

(Examples 4-6 and Comparative Examples 3 and 4)
FIG. 5 is a trial production of contact materials of Examples 4 to 6 and Comparative Examples 3 and 4 in which the content of Co as an auxiliary component in the raw material mixing step is changed within a range of 0.1 to 5 wt%, and is mounted on a vacuum valve. The results of the evaluation are shown. In Examples 4 to 6 in which the Co content is in the range of 0.2 to 5 wt%, the density of the heat treatment body is increased by the action of Co, and the porosity after repressurization can be lowered to 10% or less, so that the blocking performance, Good cutting properties. On the other hand, in Comparative Example 3 where the Co content is less than 0.1 wt%, the porosity of the heat treatment body is high, and a sufficient density cannot be obtained by re-pressurization, resulting in too low conductivity. Sufficient blocking performance is not obtained. Further, in Comparative Example 4 in which the Co content is 7 wt%, which is larger than the above range, the phase mainly composed of Co formed on the WC surface inhibits the thermal electron emission of the WC, so that the cutting characteristics are insufficient. .

(Examples 7-12 and Comparative Examples 5-8)
FIG. 6 shows Examples 7 to 12 and Comparative Examples 5 to 5 in which the auxiliary component in the raw material mixing step was changed from Co to Fe or Ni, and the changed content of Fe or Ni was changed in the range of 0.1 to 5 wt%. 8 shows the result of trial manufacture of 8 contact materials and mounting on a vacuum valve. In Examples 7 to 9 in which the Fe content is in the range of 0.2 to 5 wt% and Examples 10 to 12 in which the Ni content is in the range of 0.2 to 5 wt%, Co is used as an auxiliary component Similarly, the density of the heat-treated body is increased, and the porosity after repressurization can be lowered to 10% or less, so that the blocking performance and cutting characteristics are excellent. In particular, the blocking performance and cutting characteristics when Ni is added are good. On the other hand, in Comparative Examples 5 and 6 in which the Fe or Ni content is 0.1 wt%, which is less than the range of Examples 7 to 12, the porosity of the heat treatment body is high, and sufficient density is obtained by repressurization. However, since the electrical conductivity is too low, sufficient blocking performance is not obtained. On the other hand, in Comparative Examples 7 and 8 in which the Fe or Ni content is 7 wt%, which is larger than the range of Examples 7 to 12, the phase mainly composed of Fe or Ni formed on the WC surface causes thermionic emission of WC. Cutting properties are insufficient due to inhibition.

(Examples 13 to 15 and Comparative Examples 9 and 10)
FIG. 7 is a trial production of contact materials of Examples 13 to 15 and Comparative Examples 9 and 10 in which the porosity of the molded body in the molding process was changed in the range of 20 to 40%, and the evaluation was performed by mounting the contact materials on a vacuum valve. Results are shown. In Examples 13 to 15 in which the porosity of the compact is in the range of 25 to 35%, the reduction of the powder surface with hydrogen utilizing the voids is satisfactorily performed, and the heat treatment is performed at 1200 ° C. by adding Co. Since the aforementioned voids are taken out in a closed state and reoxidation by the outside air is suppressed, the oxygen content can be lowered to 100 ppm or less, and both the blocking performance and cutting properties are good. On the other hand, in Comparative Example 9 where the molded body porosity is 20%, which is lower than the range of Examples 13 to 15, the voids are partially closed, and the oxygen content is not sufficiently reduced by hydrogen and becomes a high value of oxygen. Therefore, sufficient shut-off performance is not obtained. On the other hand, in Comparative Example 10 where the molded body porosity is 40%, which is higher than the range of Examples 13 to 15, sufficient density cannot be obtained by re-pressurization, and the conductivity becomes too low, so that sufficient blocking performance is obtained. Not.

(Example 16 and Comparative Example 11)
FIG. 8 shows the results of comparative evaluation of Example 16 manufactured in the standard process in which the atmosphere in the reduction heat treatment process is hydrogen and Comparative Example 11 in which the atmosphere during the heat treatment is vacuum. In Example 16, since the reduction of the raw material powder is sufficient, the oxygen content can be reduced, and both the blocking performance and the cutting characteristics are good. On the other hand, in the comparative example 11, since the reduction | restoration of raw material powder is inadequate, oxygen content becomes very high and interruption | blocking performance is inadequate.

(Examples 17 to 19 and Comparative Examples 12 and 13)
FIG. 9 shows the results of trial manufacture of contact materials of Examples 17 to 19 and Comparative Examples 12 and 13 in which the heat treatment temperature in the reduction heat treatment step was changed in the range of 1100 to 1300 ° C., and mounted on a vacuum valve. Show. In Examples 17 to 19 where the heat treatment temperature is in the range of 1150 to 1250 ° C., the above-mentioned voids can be closed by heat treatment, and reoxidation by the outside air after taking out is suppressed, so that it is 120 ppm or less. The oxygen content can be lowered to a high level, and both the blocking performance and cutting properties are good. On the other hand, in Comparative Example 12 where the heat treatment temperature is lower than 1100 ° C. compared with Examples 17 to 19, there is a portion that is not closed in a part of the void after the heat treatment, which is re-oxidized and has a high oxygen content. Therefore, sufficient shut-off performance is not obtained. In Comparative Example 13, where the heat treatment temperature is as high as 1300 ° C., Ag in the heat treated body is evaporated and worn, and the electrical conductivity becomes too low, so that a sufficient blocking performance is not obtained.

(Examples 20 to 22 and Comparative Example 14)
FIG. 10 is a trial production of contact materials of Examples 20 to 22 and Comparative Example 14 in which the porosity of the pressurizing body in the pressurizing step was changed in the range of 3 to 12%, and the evaluation was carried out by mounting on the vacuum valve. Results are shown. In Examples 20 to 22 in which the molded body porosity is in the range of 3 to 10%, the air gap is sufficiently reduced and the electrical conductivity is increased, so that both the blocking performance and the cutting property are good. As in Example 20, it is difficult to reduce the porosity to 3% or less due to the equipment capacity, but the conductivity is increased as the porosity is lower, and the blocking performance is also improved. Therefore, the porosity is less than 3%. The present invention is also effective. On the other hand, in Comparative Example 14 in which the porosity of the pressurized body is as high as 12%, the electrical conductivity is not sufficiently low, so that the blocking performance is insufficient.

(Examples 23 to 25 and Comparative Examples 15 and 16)
FIG. 11 shows the results of trial manufacture of contact materials of Examples 23 to 25 and Comparative Examples 15 and 16 in which the reheat temperature in the reheat process was changed in the range of 750 to 1300 ° C., and mounting on a vacuum valve. Indicates. In Examples 23 to 25 in which the reheat treatment temperature is in the range of 800 to 1250 ° C., the electrical conductivity lowered by repressurization is sufficiently recovered, so that the interruption performance is sufficient. On the other hand, in Comparative Example 15 where the temperature of the reheat treatment is as low as 750 ° C., the electrical conductivity is not sufficiently recovered, so that the blocking performance is insufficient. On the other hand, in Comparative Example 16 reheated at 1300 ° C., Ag in the heat-treated body is evaporated and worn, and the electrical conductivity becomes too low, so that a sufficient blocking performance is not obtained.

(Examples 26 to 28 and Comparative Examples 17 and 18)
FIG. 12 shows prototypes of contact materials of Examples 26 to 28 and Comparative Examples 17 and 18 in which the bonding temperature in the electrode / contact bonding process of the vacuum valve is changed in the range of 750 to 1000 ° C., and mounted on the vacuum valve for evaluation. The result of having carried out is shown. In Examples 26 to 28 in which the reheat treatment temperature is in the range of 800 to 950 ° C., the conductivity lowered by repressurization is sufficiently recovered, so that the interruption performance is sufficient. On the other hand, in Comparative Example 17 where the temperature of the reheat treatment is as low as 750 ° C., the electrical conductivity is not sufficiently recovered, so that the blocking performance is insufficient. On the other hand, in Comparative Example 18 joined at 1000 ° C., Ag in the heat-treated body melts and flows out, and the electrical conductivity becomes too low, so that a sufficient blocking performance is not obtained.

(Examples 29 to 32)
FIG. 13 shows titanium carbide (TiC), vanadium carbide (VC), zirconium carbide (ZrC), or silicon carbide (SiC) of 10 wt% or less of the total amount of WC (total carbide) as an arc resistant component in the raw material mixing step. The result of having produced the contact material of Examples 29 to 32 replaced with, and mounting it on a vacuum valve and performing the evaluation is shown. That is, in Examples 29 to 32, the conductive component composed of 30 to 50 wt% Ag, the arc resistant component composed of 48.5 to 68.5 wt% of all carbides including 10 wt% or less of carbide other than WC, and 0 A raw material powder composed of auxiliary components composed of at least one of Co, Fe and Ni of 2 to 5 wt% is mixed. In FIG. 13, it can be seen that all of Examples 29 to 32 show good blocking performance and cutting characteristics. In Examples 29 to 32, the case where TiC, VC, ZrC, or SiC was replaced was described. However, even when TiC, VC, ZrC, and SiC are used in combination, good blocking performance and cutting characteristics can be obtained. Can do.

(Other embodiments)
As described above, the present invention has been described according to the embodiment. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, in the raw material mixing step of step S1 in FIG. 3, 25 to 35 wt% of the conductive component made of Ag may be replaced with copper (Cu). That is, a conductive component composed of 5 to 25 wt% Ag and 25 to 35 wt% Cu, an arc resistant component composed of 48.5 to 68.5 wt% WC, and 0.2 to 5 wt% Co, Fe, Ni. You may mix the raw material powder comprised with the auxiliary component which consists of at least any one of these. Also in this case, it is possible to realize a contact material having a good breaking performance and cutting characteristics as in the case where the conductive component is made of only 30 to 50 wt% of Ag.

  Moreover, the experimental data shown in FIGS. 4 to 13 are merely examples, and it is a matter of course that the knowledge of the present invention has been found from a larger amount of data.

  As described above, the present invention naturally includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

It is the fragmentary sectional view which carried out the cross section display of the interruption | blocking chamber of the vacuum valve to which the contact material for vacuum valves which concerns on embodiment of this invention is applied. It is the fragmentary sectional view which expanded the electrode part shown in FIG. It is a flowchart for demonstrating an example of the manufacturing method of the contact material for vacuum valves which concerns on embodiment of this invention, and the manufacturing method of a vacuum valve. It is a table | surface which shows the evaluation result of Examples 1-3 which concern on embodiment of this invention, and Comparative Examples 1 and 2. FIG. It is a table | surface which shows the evaluation result of Examples 4-6 which concern on embodiment of this invention, and Comparative Examples 3 and 4. FIG. It is a table | surface which shows the evaluation result of Examples 7-12 which concern on embodiment of this invention, and Comparative Examples 5-8. It is a table | surface which shows the evaluation result of Examples 13-15 and Comparative Examples 9 and 10 which concern on embodiment of this invention. It is a table | surface which shows the evaluation result of Example 16 and Comparative Example 11 which concern on embodiment of this invention. It is a table | surface which shows the evaluation result of Examples 17-19 and Comparative Examples 12 and 13 which concern on embodiment of this invention. It is a table | surface which shows the evaluation result of Examples 20-22 and the comparative example 14 which concern on embodiment of this invention. It is a table | surface which shows the evaluation result of Examples 23-25 and Comparative Examples 15 and 16 which concern on embodiment of this invention. It is a table | surface which shows the evaluation result of Examples 26-28 and Comparative Examples 17 and 18 which concern on embodiment of this invention. It is a table | surface which shows the evaluation result of Examples 29-32 which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Shut off chamber 2 ... Insulation container 3a ... Sealing metal fitting 4a ... Cover body 5, 6 ... Conductive rod 7, 8 ... Electrode 9 ... Bellows 10, 11 ... Arc shield 12, 14 ... Brazing material 13a, 13b ... Contact

Claims (5)

At least one of a conductive component composed of 30 to 50% by weight of silver, an arc resistant component composed of 48.5 to 68.5% by weight of tungsten carbide, and 0.2 to 5% by weight of cobalt, iron, and nickel A step of mixing an auxiliary component consisting of to obtain a mixed powder;
Molding the mixed powder so that the porosity is 25 to 35% to obtain a molded body;
Heat-treating the molded body at 1150 to 1250 ° C. in a reducing atmosphere to obtain a heat-treated body;
Pressurizing the heat-treated body so as to have a porosity of 10% or less to obtain a pressurized body.   The method for producing a contact material according to claim 1, further comprising a step of heat-treating the pressure body at 800 to 1250 ° C. after the step of obtaining the pressure body. A conductive component composed of 5 to 25% by weight silver and 25 to 35% by weight copper, an arc resistant component composed of 48.5 to 68.5% by weight tungsten carbide, 0.2 to 5% by weight cobalt, A step of mixing an auxiliary component consisting of at least one of iron and nickel to obtain a mixed powder;
Molding the mixed powder so that the porosity is 25 to 35% to obtain a molded body;
Heat-treating the molded body at 1150 to 1250 ° C. in a reducing atmosphere to obtain a heat-treated body;
Pressurizing the heat-treated body so that the porosity is 10% or less. An arc-resistant component composed of 30 to 50% by weight of silver, 48.5 to 68.5% by weight of all carbides including 10% or less of carbide other than tungsten carbide, and 0.2 to 5% by weight. % Of a raw material powder composed of an auxiliary component composed of at least one of cobalt, iron, and nickel to obtain a mixed powder;
Molding the mixed powder so that the porosity is 25 to 35% to obtain a molded body;
Heat-treating the molded body at 1150 to 1250 ° C. in a reducing atmosphere to obtain a heat-treated body;
Pressurizing the heat-treated body so as to have a porosity of 10% or less to obtain a pressurized body. At least one of a conductive component composed of 30 to 50% by weight of silver, an arc resistant component composed of 48.5 to 68.5% by weight of tungsten carbide, and 0.2 to 5% by weight of cobalt, iron, and nickel A step of obtaining a mixed powder by mixing with an auxiliary component comprising: a step of forming the mixed powder so as to have a porosity of 25 to 35% to obtain a molded body; and a step of 1150 in the reducing atmosphere in the reducing body. A step of producing a contact material by heat-treating at 1250 ° C. to obtain a heat-treated body and pressurizing the heat-treated body so that the porosity is 10% or less;
Bonding the contact material to a pair of electrodes at 800 to 950 ° C., respectively.

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