JP2006032036A - Contact material for vacuum valves - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a contact material for a vacuum valve in which the withstand voltage required for the contact material of a vacuum valve used for a vacuum circuit breaker or the like and the stability of the breaking performance are improved.
A contact material for a vacuum valve composed of a conductive component, an arc-proof component, a third component, and an auxiliary component as required, comprising a conductive component Cu, an arc-proof component Cr, and a third component α (arc-proof component average) For example, W) powder having an average particle diameter of 3 times or less of the particle diameter is mixed and pressure-molded, followed by liquid phase sintering. Thereby, Cr is crystallized in the vicinity of the third component α, and a contact material for a vacuum valve with improved cut-off characteristics and withstand voltage characteristics can be obtained.
[Selection] Figure 1

Description

  The present invention relates to a contact material for a vacuum valve that has improved withstand voltage performance and break-off performance among characteristics required for contact material of a vacuum valve used in a vacuum circuit breaker or the like.

  The characteristics required for contact materials for vacuum valves are the three basic requirements indicated by each performance for withstand voltage characteristics, breaking characteristics, and welding characteristics, as well as electrical resistance (bulk resistance and contact resistance) and temperature rise. Low and stable is an important requirement.

  However, because some of these requirements are contradictory, it is impossible to satisfy all the requirements with a single metal species. For this reason, in many contact materials that have been put to practical use, two or more types of materials that can compensate for the insufficient properties, for example, a combination of a conductive component and an arc-resistant component for large currents or high voltages, etc. Thus, contact materials suitable for specific applications have been developed, and materials having excellent characteristics to some extent have been developed. Needless to say, current can be opened and closed with a high probability for the purpose of use as a switch.

  Even in the conventional invention, there is an invention that has been filed and published by the Company under the title of “contact material for vacuum valve, manufacturing method thereof, and vacuum valve” (see Patent Document 1). The first arc resistant component is Cr and the second arc resistant component is any one of W, Mo, Ta, Nb or a combination thereof, whereas in the present invention, the arc resistant component is not limited to Cr. Furthermore, the third component of the present invention is not limited to the role of only the arc-resistant component, but the core when the arc-resistant component solid-solved in the conductive component is crystallized during liquid phase sintering. The role as a sintering aid is expected. Therefore, the third component referred to in the present invention is not limited to a metal, and is also characterized by being a component that hardly dissolves in a conductive component.

In addition, there is one that has been filed and published by Siemens under the title "Method for producing a copper-chromium molten alloy as a contactor material for a vacuum circuit breaker" (see Patent Document 2). The present invention is characterized in that both Cu and Cr are melted and manufactured, whereas the present invention is different in that only a conductive component such as Cu is melted.
JP 2003-226904 A Japanese Examined Patent Publication No. 4-71970

  In order to fully exhibit the withstand voltage performance and interruption performance of the vacuum valve, it is preferable that fine particles are present in the structure of the contact material and that the gas content in the contact is small.

  Conventional contact materials often use fine raw material powders due to the presence of fine particles. In that case, the specific surface area of the raw material powders increases extremely, and the gas content in the contacts also increases. As a result, it is often impossible to obtain stable interrupting performance and withstand voltage performance.

  The present invention has been made in view of such conventional points, and is a vacuum that improves the withstand voltage required for the contact material of a vacuum valve used for a vacuum circuit breaker and the stability of the breaking performance. An object is to provide a contact material for a valve.

  In order to achieve the above object, a contact material for a vacuum valve according to the present invention is a contact material for a vacuum valve composed of at least a conductive component, an arc resistant component, and a third component, and is a raw material powder of the third component As described above, a material having an average particle size of 3 times or less of the average particle size of the raw material powder of the arc-resistant component is used, and is manufactured by liquid phase sintering.

  ADVANTAGE OF THE INVENTION According to this invention, the contact material for vacuum valves which improved the interruption | blocking characteristic and the withstand voltage characteristic can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  As described above, the presence of fine Cr particles and a low gas content are necessary in order to fully demonstrate the performance of contact materials for vacuum valves, such as the withstand voltage performance and interruption performance of Cu-Cr contacts. It is.

  That is, the feature of this embodiment is that it has both a fine structure and a low gas amount. As a specific means for obtaining this, it is possible to manufacture by adding a third component α which is hardly dissolved in Cu and performing liquid phase sintering to crystallize Cr in the vicinity of α. For example, as shown in FIG. 1, powders of a conductive component Cu, an arc-proof component Cr, and a third component α are mixed and pressure-molded, followed by liquid phase sintering (sintering at a temperature equal to or higher than the melting point of Cu). By doing so, Cr is crystallized around the third component α. In this case, the finer the third component α serving as a nucleus, the larger the number of particles, and the larger the number of Cr crystallized around the third component α.

  Note that the gist of the present invention is not limited to Cu—Cr contacts, but can be applied to contact materials composed of other conductive components, other arc-proof components, and, if necessary, auxiliary components.

  According to the present embodiment, it is possible to combine a fine structure and a low gas amount, and it is possible to stabilize the withstand voltage performance, the breaking performance, and the like, and to improve the contact performance.

  Examples of the present invention will be described below. First, a configuration example of a vacuum valve to which the contact material for a vacuum valve of the present invention is applied will be described with reference to FIGS.

  In FIG. 2, reference numeral 1 denotes a shut-off chamber. The shut-off chamber 1 includes an insulating container 2 formed in a substantially cylindrical shape by an insulating material, and metallic lids provided at both ends via sealing fittings 3a and 3b. The bodies 4a and 4b are vacuum-tight. 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. It is said. A bellows 9 is attached to the electrode rod 6 of the movable electrode 8 so that the electrode 8 can be moved in the axial direction while keeping the inside of the shut-off chamber 1 in a vacuum-tight state. A shield 10 is provided to prevent the bellows 9 from being covered with arc vapor. 11 is a metallic arc shield provided in the shutoff chamber 1 so as to cover the electrodes 7 and 8 and prevents the insulating container 2 from being covered with arc vapor. Further, as shown in an enlarged view in FIG. 3, the electrode 8 is fixed to the conductive rod 6 by a brazing portion 12, or is crimped and connected by caulking. The contact 13 a is fixed to the electrode 8 with a brazing 14. In addition, 13b in FIG. 2 is a fixed side contact.

  Next, based on FIG. 4, examples of the contact materials for vacuum valves of the present invention, manufacturing methods of comparative examples, and measurement results of the breaking characteristics and withstand voltage characteristics will be described.

(Comparative Examples 1-2, Examples 1-3)
In Comparative Example 1, a Cu-50Cr contact was produced by a liquid phase sintering method using fine Cr powder (with a correspondingly large gas content) without adding the third component α. Cu powder (average particle size 30 μm) and Cr powder (average particle size 10 μm) were mixed so as to have a weight ratio of 1: 1, and a green compact formed at 10 t / cm ² with a φ60 mm mold was used as a crucible with φ70 mm. Then, the periphery of the green compact was covered and filled with alumina powder, and then liquid phase sintered in a vacuum of the order of 10 ⁻³ Pa under conditions of 1200 ° C. × 60 minutes to obtain a plurality of Cu-50Cr alloys. .

  This Cu—Cr alloy was processed into a predetermined contact shape (φ50 mm, t5 mm) while observing the structure of the cross section and measuring the amount of oxygen. The characteristics of the cross-sectional structure and the measured values of the oxygen content are shown in FIG. The processed contact material was incorporated into a vacuum valve, and a breaking test and a withstand voltage test were conducted. In the interruption test, the maximum interruption current was measured by gradually increasing the current value from 5 kA. In addition, a withstand voltage test was performed on the contacts after the interruption test. In the withstand voltage test, the dielectric breakdown voltage was measured 100 times with a constant electrode interval (about 5 mm), and the average value was calculated. Based on the measurement results of Comparative Example 1, the other measurement results are shown as relative values.

  In Example 1, a Cu-48Cr-2W alloy was produced by the same liquid phase sintering as in Comparative Example 1. However, the average particle size of the raw material powder was 30 μm for Cu, 50 μm for Cr, 130 μm for W, and the mixing ratio (weight ratio) was Cu: Cr: W = 50: 48: 2. The cross-sectional structure of the prepared Cu-48Cr-2W alloy is dotted with fine Cr particles having a particle size of about 20 μm in the vicinity of W particles or at places where it was thought that the grain boundaries of the Cu matrix were previously used. The amount was 800 ppm. As a result of evaluating the electrical characteristics, the cutoff characteristics and the withstand voltage characteristics were 1.1 times and 1.1 times that of Comparative Example 1, respectively.

  In Example 2, a Cu-24Cr-1Mo alloy was produced by the same liquid phase sintering as in Comparative Example 1. However, the average particle size of the raw material powder was 30 μm for Cu, 150 μm for Cr, 3 μm for Mo, and the mixing ratio (weight ratio) was Cu: Cr: Mo = 75: 24: 1. As for the cross-sectional structure of the produced Cu-24Cr-1Mo alloy, fine Cr particles having a particle size of about 10 μm were scattered in the vicinity of the fine Mo particles, and the amount of oxygen in the alloy was 600 ppm. As a result of evaluating the electrical characteristics, the breaking characteristics and the withstand voltage characteristics were 1.3 times and 1.1 times that of Comparative Example 1, respectively.

  In Example 3, a Cu-55Cr-1Ta alloy was produced by a sintering infiltration method that is one type of liquid phase sintering. Cu-55Cr-1Ta alloy was sintered under conditions of 1200 ° C. for 120 minutes in a hydrogen atmosphere after Cr powder (average particle size 150 μm) and Ta powder (average particle size 15 μm) were mixed and pressed. The Cr (+ Ta) skeleton and the infiltrant Cu produced in this way are placed one above the other in a crucible and heated to 1200 ° C. in a hydrogen atmosphere and held for 120 minutes to infiltrate Cu as a conductive component. It was produced by. As for the cross-sectional structure of the produced Cu-55Cr-1Ta alloy, fine Cr particles having a particle size of about 20 μm were scattered in the vicinity of the Ta particles, and the oxygen content in the alloy was 400 ppm. As a result of evaluating the electrical characteristics, the breaking characteristics and the withstand voltage characteristics were 1.1 times and 1.2 times that of Comparative Example 1, respectively.

  In Comparative Example 2, a Cu-48Cr-2W alloy was produced by the same liquid phase sintering as in Comparative Example 1. However, the average particle diameter of the raw material powder was 30 μm for Cu, 50 μm for Cr, and 170 μm for W, and the mixing ratio (weight ratio) was Cu: Cr: W = 50: 48: 2. In the cross-sectional structure of the produced Cu-48Cr-2W alloy, Cr particles having a particle size equivalent to that of the raw material powder of about 50 μm existed, and the oxygen content in the alloy was 800 ppm. As a result of evaluating the electrical characteristics, the breaking characteristics and the withstand voltage characteristics were 1.0 times and 1.0 times that of Comparative Example 1, respectively, and there was almost no improvement effect.

  From the results of Comparative Examples 1 and 2 and Examples 1 to 3, the electrical properties of the breaking characteristics and the withstand voltage characteristics are obtained by liquid phase sintering in which the third component is added in addition to the conductive component Cu and the arc resistant component Cr. Improvement is possible. The average particle size of the third component raw material powder is effective to be not more than 3 times the average particle size of the raw material resistant component powder, and the characteristic improvement becomes remarkable when it is preferably 1/10 or less.

(Comparative Examples 3-4, Examples 4-5)
In Comparative Examples 1 and 2 and Examples 1 to 3, the case where the sintering temperature is 1200 ° C., that is, the temperature is + 117 ° C. based on the melting point of the conductive component Cu (1083 ° C.) is described. However, the gist of the present invention is not limited to this.

  In Comparative Example 3, Examples 4 to 5, and Comparative Example 4, Cu-24Cr-1WC alloys were produced at sintering temperatures of 1100 ° C., 1150 ° C., 1250 ° C., and 1300 ° C., respectively. The average particle diameter of the raw material powder was 30 μm for Cu, 150 μm for Cr, 0.8 μm for WC, and the mixing ratio (weight ratio) was Cu: Cr: WC = 75: 24: 1.

  Of these, Comparative Example 4 sintered at 1300 ° C. was broken in appearance and clearly separated from Cu and Cr, and thus was judged not worthy of electrical evaluation of the contacts. For the remaining three types of Cu-24Cr-1WC alloys, the material characteristics were evaluated, and after processing into a predetermined shape, the electrical characteristics were evaluated.

  In Comparative Example 3, there were no fine Cr particles, and the interruption characteristics and withstand voltage characteristics were 1.0 times and 1.0 times that of Comparative Example 1, respectively, and were not improved. This is because the crystallization of Cr was not promoted because the sintering temperature was low.

  In Example 4, fine Cr having a particle diameter of about 10 μm was scattered, and the breaking characteristics and the withstand voltage characteristics were 1.2 times and 1.2 times that of Comparative Example 1, respectively.

  In Example 5, fine Cr having a particle size of about 10 μm was scattered, and the cutoff characteristics and the withstand voltage characteristics were 1.3 times and 1.2 times that of Comparative Example 1, respectively.

  As described above, when the sintering temperature is lower than + 20 ° C. based on the melting point of the conductive component Cu, Cu dissolves, but crystallization of fine Cr particles does not appear remarkably. On the other hand, if the sintering temperature exceeds + 200 ° C. based on the melting point of the conductive component Cu, the shape of Cu, in other words, the shape of the contact cannot be maintained. Furthermore, Cu and Cr are two-phase separated, and the uniformity of the structure cannot be maintained. Accordingly, the sintering temperature of the contact material is preferably + 20 ° C. or higher and + 200 ° C. or lower based on the melting point (1083 ° C.) of the conductive component Cu.

(Examples 6 to 10)
In Examples 6 to 10, a Cu-24Cr-5WC alloy was produced by liquid phase sintering in a vacuum atmosphere and then heat-treated for 30 minutes in a vacuum atmosphere, and the heat treatment temperature was used as a parameter.

  In Example 6, the electrical characteristics were evaluated by heat treatment at 1070 ° C., and the cutoff characteristics and the withstand voltage characteristics were 1.2 times and 1.1 times that of Comparative Example 1, respectively.

  In Example 7, the electrical characteristics were evaluated by heat treatment at 1050 ° C., and the interruption characteristics and the withstand voltage characteristics were 1.2 times and 1.1 times that of Comparative Example 1, respectively. It was improved. This is because the conductivity is improved by the heat treatment.

  In Example 8, the electrical characteristics were evaluated by heat treatment at 850 ° C., and the interruption characteristics and the withstand voltage characteristics were 1.3 times and 1.1 times that of Comparative Example 1, respectively. It was improved.

  In Example 9, the electrical characteristics were evaluated by heat treatment at 700 ° C., and the cutoff characteristics and the withstand voltage characteristics were 1.2 times and 1.1 times of Comparative Example 1, respectively. It was improved.

  In Example 10, the electrical characteristics were evaluated by heat treatment at 650 ° C., and the cutoff characteristics and the withstand voltage characteristics were 1.1 times and 1.1 times that of Comparative Example 1, respectively. It did not improve. This is because the heat treatment temperature was low and the effect of improving conductivity was small.

  From the results of Examples 6 to 10 described above, it is possible to improve the electrical characteristics, in particular, the blocking characteristics, when heat treatment is performed after liquid phase sintering. In particular, when the heat treatment temperature is −20 ° C. or lower and −400 ° C. or higher on the basis of the melting point (1083 ° C.) of the conductive component Cu, the characteristic improvement becomes remarkable. When the heat treatment temperature is higher than −20 ° C. on the basis of the melting point of the conductive component Cu, the characteristics are not bad, but the control of the furnace becomes difficult and the yield is deteriorated. When the heat treatment temperature is lower than −400 ° C. based on the melting point of the conductive component Cu, the heat treatment effect is low and the improvement effect is small.

(Examples 11 to 16)
In Comparative Examples 1 to 4 and Examples 1 to 10, examples of contact materials in which the conductive component is Cu, the arc resistant component is Cr, and the third component is W, Mo, Ta, and WC are described. The gist is not limited to this.

  In Example 11, an Ag-20WC-1Fe contact with Ag as the conductive component, WC as the arc resistance component, and Fe as the third component was prepared by a liquid phase sintering method, and the breaking characteristics and the withstand voltage characteristics were evaluated. The breaking characteristics and the withstand voltage characteristics were 1.3 times and 1.2 times that of the Ag-WC contact when manufactured by the usual liquid phase sintering method without adding the third component, respectively.

  In Example 12, an Ag / Cu-60WC-1Co contact having a conductive component of Ag + Cu, an arc resistant component of WC, and a third component of Co was prepared by a liquid phase sintering method, and the breaking characteristics and the withstand voltage characteristics were evaluated. As a result, the breaking characteristics and the withstand voltage characteristics were 1.2 times and 1.2 times that of the Ag-WC contact when manufactured by the usual liquid phase sintering method without adding the third component, respectively. .

In Examples 13 to 16, the conductive component is Cu, the arc resistant components are W, Nb, WC, and Cr + W, respectively, and the third components are Sb (1 wt%), Al ₂ O ₃ (1 wt%), and WB, respectively. (2 wt%), TiN (2 wt%) as a contact material was manufactured by liquid phase sintering, and the electrical characteristics were evaluated. As a result, all of Examples 13 to 16 were not added with the third component. It was 1.2 times that of the contact when manufactured by liquid phase sintering, and the withstand voltage characteristic was 1.1 times.

  When the third component exceeds 5 wt%, at least one of the cutoff characteristic and the withstand voltage characteristic is deteriorated.

(Examples 17 to 19)
In Comparative Examples 1 to 4 and Examples 1 to 16, examples of contact materials composed of a conductive component, an arc resistant component, and a third component have been described. However, the gist of the present invention is not limited to this.

  In Examples 17 to 19, the auxiliary components are Bi (0.1 wt%), Te (5 wt%), and Te + Se (4 wt%), respectively, which is one type of liquid phase sintering method as in Example 3. As a result of manufacturing the contact material by the sintering infiltration method and evaluating the electrical characteristics, the breaking characteristics were obtained when all the Examples 17 to 19 were manufactured by the normal sintering infiltration method without adding the third component. The contact point was 1.2 times that of the contact, and the withstand voltage characteristic was 1.1 times.

  When the auxiliary component exceeds 5 wt%, at least one of the cutoff characteristic and the withstand voltage characteristic deteriorates.

  As can be seen from the above results, the present invention makes it possible to improve the interruption characteristics and withstand voltage characteristics of the contact material for vacuum valves.

(Other examples)
In the above embodiment, the conductive component is only described in terms of Cu, Ag, and Ag + Cu. However, if Cu or Ag is the main component, for example, a trace amount of Cr, Sn, or the like may be contained. Similar effects can be obtained.

  In addition, regarding the arc-proof component, in the above-described embodiments, there is only description of Cr, W, Nb, WC, Cr + W, but at least one of Cr, W, Nb, Ta, Ti, Mo and their carbides. Even if is used as an arc-proof component, the same effect can be obtained.

Further, regarding the third component, in the above embodiment, there is only description of W, Mo, Ta, Co, Fe, Sb, WC, WB, Al ₂ O ₃ , TiN, but W, Mo, Cr, Co, Even when at least one of Fe, Nb, Ta, Ti, Al, Sb and their carbides, borides, oxides, and nitrides is used as the third component, the same effect can be obtained.

  The auxiliary component is also described in the above embodiment only when Bi, Te, Te + Se, but the same effect can be obtained even if at least one of Bi, Te, Se is used as the auxiliary component.

The figure which showed the typical manufacturing process of the contact material for vacuum valves which concerns on one Embodiment of this invention. Sectional drawing which shows an example of the vacuum valve to which the contact material for vacuum valves of this invention is applied. The principal part expanded sectional view of FIG. The table | surface which shows the manufacturing conditions and evaluation result of each Example and comparative example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Shut-off chamber 2 ... Insulation container 3a, 3b ... Sealing metal fittings 4a, 4b ... Cover body 5, 6 ... Conductive rod 7 ... Fixed electrode 8 ... Movable electrode 9 ... Bellows 10, 11 ... Arc shield 12, 14 ... Brazing Part 13a ... Moving side contact 13b ... Fixed side contact

Claims (10)

  A contact material for a vacuum valve comprising at least a conductive component, an arc resistant component, and a third component, wherein the raw material powder of the third component is not more than three times the average particle diameter of the raw material powder of the arc resistant component A contact material for a vacuum valve, wherein a material having an average particle diameter is used and manufactured by liquid phase sintering.   The raw material powder of the third component hardly dissolves in the conductive component, and the average particle size thereof is 1/10 or less of the average particle size of the raw material powder of the arc resistant component, and is in the vicinity of the finer third component. 2. The contact material for a vacuum valve according to claim 1, wherein an arc-resistant component is present in the vacuum valve.   The vacuum valve contact material is manufactured by a sintering method in a non-oxidizing atmosphere, and the sintering temperature is + 20 ° C. or higher and + 200 ° C. or lower based on the melting temperature of the conductive component. 3. The contact material for a vacuum valve according to claim 1, wherein the contact material is a vacuum valve.   The contact material for the vacuum valve has been subjected to heat treatment in a non-oxidizing atmosphere after liquid phase sintering, and the heat treatment temperature is −20 ° C. or less based on the melting temperature of the conductive component, − The contact material for a vacuum valve according to any one of claims 1 to 3, wherein the contact temperature is 400 ° C or higher.   The contact material for a vacuum valve according to any one of claims 1 to 4, wherein the conductive component contains at least one of Cu and Ag as a main component.   6. The vacuum valve according to claim 1, wherein the arc-resistant component contains at least one of Cr, W, Nb, Ta, Ti, Mo and carbides thereof. Contact material.   The third component contains at least one of W, Mo, Cr, Co, Fe, Nb, Ta, Ti, Al, Sb and carbides, borides, oxides, and nitrides thereof. The contact material for a vacuum valve according to any one of claims 1 to 6.   The contact material for a vacuum valve according to claim 7, wherein the total content of the third components of the contact material is 5 wt% or less.   9. The vacuum valve contact material contains an auxiliary component, and the auxiliary component contains at least one of Bi, Te, and Se. The contact material for vacuum valves as described. The contact material for a vacuum valve according to claim 9, wherein the total content of the auxiliary components is 5 wt% or less.

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