JP4620071B2 - Contact materials for vacuum circuit breakers - Google Patents

Description

  The present invention relates to a Cu-Cr alloy powder and a contact material for a vacuum circuit breaker using the same, and in particular, a Cu-Cr alloy powder capable of improving powder formability in a production process by a solid phase method and the same. The present invention relates to a contact material for a vacuum circuit breaker.

The circuit breaker is used in combination with an overcurrent relay that detects a failure state in the event of an abnormality such as a grounding accident or a short-circuit accident, and automatically shuts off the electric circuit instantaneously. Widely used in power equipment, substation equipment, high-speed railway vehicles, etc. In particular, the vacuum circuit breaker opens and closes the electric circuit by opening and closing a pair of contact members (contacts) arranged oppositely in a container (vacuum valve) maintained at a high vacuum of about 10 ⁻⁴ Pa. .

  FIG. 1 is a sectional view showing an example of the structure of a general vacuum circuit breaker. In FIG. 1, a shut-off chamber 1 in which contacts are opened and closed is provided with an insulating container 2 made of an insulating material and formed in a substantially cylindrical shape, and upper and lower ends of the insulating container 2 via sealing metals 3 a and 3 b. A compartment is formed by the metallic lids 4a and 4b and is configured to be vacuum-tight. A pair of conductive rods 5 and 6 are arranged in the blocking chamber 1 so as to face each other in the axial direction, and a pair of electrodes 7 and 8 are attached to opposite ends of the respective conductive rods 5 and 6. . In the figure, the upper electrode 7 is a fixed electrode, while the lower electrode 8 is a movable electrode. The conductive rod 6 of the movable electrode 8 is provided with an expandable / contractible bellows 9, which enables the movable electrode 8 to reciprocate in the axial direction while keeping the inside of the blocking chamber 1 vacuum-tight. A metal arc shield 10 is provided on the top of the bellows 9, and the arc shield 10 prevents the bellows 9 from being covered with arc vapor.

  Further, a metal arc shield 11 is disposed in the shut-off chamber 1 so as to cover a pair of opposed electrodes 7, 8, and the arc shield 11 prevents the insulating container 2 from being covered with arc vapor. Is done.

  Further, as shown in FIG. 2 in an enlarged manner, the electrode 8 is fixed to the brazed portion 12 formed at the end of the conductive rod 6 by heat bonding, or is crimped and connected by caulking. The contact member 13a is integrally fixed to the center portion of the end surface of the electrode 8 via a brazing material 14. Similarly, the fixed-side contact member 13b shown in FIG. 2 is integrally joined to the end surface of the fixed electrode 7 via a brazing material.

  According to the vacuum circuit breaker of the said structure, since the high dielectric strength in a high vacuum can be utilized, it has the characteristic which can shorten the opening / closing stroke of the contact member which opposes.

  Generally, the characteristics required as a contact material are: (1) high breaking capacity, (2) high withstand voltage, (3) low contact resistance, because the contacts open and close frequently. 4) Small welding power, (5) Small contact consumption, (6) Small cutting current value, (7) Good formability (workability), (8) Sufficient mechanical strength ( (Hardness). However, in an actual contact material, it is difficult to satisfy all of these characteristics at the same time. Generally, a material that satisfies particularly important characteristics depending on the application and sacrifices some other characteristics is used. The current situation is.

  As the above contact material, arc resistance (arc resistance) and welding resistance are indispensable so as not to be welded by an arc generated at the time of frequent opening and closing of the contact, while high conductivity is maintained in order to maintain low contact resistance. Since it is an indispensable requirement to make the characteristics the main required characteristics, contact materials having arc resistance (arc resistance) and welding resistance are actually used in many applications. Specific contact constituent materials satisfying both the arc resistance and the high conductivity include, for example, Ag-based, Ag-Cu-based material, Ag-CdO-based material, 30% Cu-W-based material, and 50% Cu--. There are Cr-based materials. In particular, the Cu—W contact material is excellent in conductivity, while the Cu—Cr contact material is excellent in withstand voltage characteristics, and thus is particularly popular as a contact material for high-power electrical equipment.

  This Cu-Cr contact material is composed mainly of Cu having high conductivity, and Cr which is inferior in conductivity compared to Cu but has a high melting point and excellent arc resistance and voltage resistance. It achieves both high voltage resistance and large current interruption required for contact materials. Cu-Cr contact materials that have both high voltage resistance and large current interruptability are expected to expand their use to power facilities, substation facilities, railway vehicles, etc., while the vacuum circuit breaker itself There is also a technical request for downsizing, and further performance improvement is required.

  Among the contact materials, a Cu—Cr-based contact material that is particularly suitable as a contact material for high-power devices is, for example, formed of a mixed powder or atomized powder of Cu powder and Cr powder and sintered at a high temperature of about 1050 ° C. It is manufactured by a powder metallurgy method, a method in which Cu is infiltrated into a porous Cr calcined body, or a method in which Cr and Cu are dissolved at a predetermined composition ratio.

  Particularly in the powder metallurgy method, it is possible to form a shape close to the final product, and there is an advantage that the raw material cost can be reduced and the blending accuracy of the composition ratio of the Cu component and the Cr component can be increased. . On the other hand, since the powder metallurgy method is a method of forming a sintered body by solid phase sintering, the melting point of the material having the lowest melting point (Cu in the case of Cu-Cr-based material) among the constituent materials of the contact member In the above, there is a restriction that heating cannot be performed, and there is a problem that it is difficult to remove impurities by volatilization as compared with the infiltration method or the dissolution method. Therefore, in recent years, the atomization method, the rotating electrode method, the centrifugal spray method, and the like are used for the purpose of removing the impurities, and attempts have been made to obtain Cu—Cr alloy powders with less impurities by these methods. . Since the withstand voltage can be improved by obtaining a Cu—Cr alloy powder with few impurities, removing impurities is an important issue in improving the characteristics of contact materials.

The Cu—Cr alloy powder produced by the atomizing method, rotating electrode method, centrifugal spraying method, etc. has a structure in which impurities are effectively reduced and fine Cr is dissolved or precipitated in the Cu phase. It is thought that this structure contributes to the improvement of the breaking characteristics (welding resistance) of the vacuum circuit breaker.
Japanese Examined Patent Publication No. 58-48662

  However, impurities such as oxygen and metals are removed by conventional dispersion, quenching, and other atomization methods, rotating electrode methods, and centrifugal spraying methods, improving the purity of Cu-Cr alloy powder and improving the withstand voltage. On the other hand, the hardness of the alloy powder becomes extremely high because it contains a large amount of Cr dissolved in a supersaturated state in the Cu phase of the Cu-Cr alloy powder, and the formability of the alloy powder is improved. There was a problem that worsened. In other words, the molding pressure must be set very high in order to obtain a predetermined molded body density, which cannot be handled by a general-purpose pressure molding machine. In particular, a pressure molding machine with a high strength specification that can withstand high pressure is essential. Thus, there was a problem that the manufacturing equipment cost was enormous.

  Also, because the molding pressure is very high, wear and breakage of the press molding dies are likely to occur frequently, requiring a lot of labor for re-grinding and replacement of the dies, and complicated operation and maintenance management of the manufacturing equipment. In addition, the production line must be frequently stopped for the maintenance and management, and the production efficiency (mass productivity) is greatly reduced.

  On the other hand, the infiltration method has a drawback that the removal of impurities is insufficient. In the melting method, metal impurities can be volatilized and removed, but recontamination from a magnesia or calcia crucible generally used as a melting tank may occur, and the composition control is difficult. There were also many problems that led to a decrease in the breaking characteristics of the contacts due to segregation problems.

  The present invention has been made in order to solve the above-mentioned problems, and has low impurity content, and by reducing the solid solution concentration of Cr dissolved in the Cu phase, the hardness is reduced and formability is reduced. An object of the present invention is to provide a contactor material for a vacuum circuit breaker that can be improved and mass-produced easily, a manufacturing method thereof, and a vacuum circuit breaker.

  In order to achieve the above object, the present inventors adopt a method of efficiently removing impurities by melt dispersion and rapid cooling treatment of the alloy material, while being dissolved in the Cu phase of the contact material by the rapid cooling treatment. A method for reducing the solid solution concentration of Cr was studied. In particular, in the step of obtaining the Cu—Cr alloy powder after the rapid cooling treatment, the heat treatment was followed by the cooling treatment, and the conditions such as temperature and time were variously changed. And as a result of investigating the influence which those conditions have on the moldability (workability) of Cu-Cr alloy powder, the following knowledge was acquired. That is, the Cu—Cr alloy powder obtained by the rapid cooling treatment was reheated to a predetermined temperature, and then gradually cooled to a predetermined temperature over a period of 30 minutes, so that it was dissolved in the Cu phase. By precipitating Cr and separating Cu and Cr into two phases, the amount of Cr dissolved in the Cu phase can be reduced to 200 ppm or less, preferably 20 ppm or less. It was found that the moldability can be improved by reducing the hardness. The present invention has been completed based on the above findings.

That, C u-Cr alloy powder Ru used for vacuum circuit breaker contacts is obtained by melt dispersed Cu-Cr material consisting of Cr as Cu and arc-proof component as highly conductive component, to further quench Cu in -Cr alloy powder, the solid solution concentration of Cr in the Cu phase is 200ppm or less, preferably at 20ppm or less.

  Moreover, in the said Cu-Cr alloy powder, it is preferable that the solid solution concentration of Cr in a Cu phase is 20 ppm or less.

The Cu-Cr alloy powder used for the contact for the vacuum circuit breaker is Cu-Cr obtained by melting and dispersing a Cu-Cr material composed of Cu as a highly conductive component and Cr as an arc resistant component, and further rapidly cooling. In the alloy powder, the Vickers hardness is preferably 60 Hv or less.

Further, in the present invention , the Cu—Cr alloy powder used for the contact for the vacuum circuit breaker is obtained by melting and dispersing a Cu—Cr material composed of Cu as a high conductive component and Cr as an arc resistant component, and further rapidly cooling the Cu—Cr alloy powder. A step of adjusting the Cr alloy powder, a step of heat-treating the obtained Cu-Cr alloy powder at a temperature of 800 ° C. to 1080 ° C. to separate Cu and Cr into two phases, and a temperature of 500 ° C. to 700 ° C. from the heat treatment temperature. It is preferable to manufacture by the process of cooling over 30 minutes or more to the temperature which is below ℃.

In the Cu—Cr alloy powder used in the present invention, the Cr content is preferably in the range of 20 to 70% by weight.

Furthermore, the contact material for a vacuum circuit breaker according to the present invention adjusts the Cu-Cr alloy powder by melting and dispersing a Cu-Cr material composed of Cu as a highly conductive component and Cr as an arc resistant component, and further rapidly cooling. A step of heat-treating the obtained Cu—Cr alloy powder at a temperature of 800 ° C. or higher and 1080 ° C. or lower to separate Cu and Cr into two phases, and from the heat treatment temperature to a temperature of 500 ° C. or higher and 700 ° C. or lower. A Cu-Cr alloy powder having a Cr solid solution concentration of not more than 20 ppm and a Vickers hardness of not more than 60 Hv produced by press-molding, for 30 minutes or more, It is manufactured. In the contact material for a vacuum circuit breaker, the Vickers hardness of the Cu—Cr alloy powder is preferably 55 Hv or more and 60 Hv or less.

The contact material for a vacuum circuit breaker to which the present invention is directed is a contact material composed of a Cu phase as a highly conductive component and Cr as an arc resistant component, and the solid solution concentration of Cr in the Cu phase is 200 ppm or less, preferably 20 ppm or less. der Ru. Moreover, it is preferable to make Cr content into the range of 20 to 70 weight%.

  Here, Cr as an arc resistant component is a component that is excellent in arc resistance and welding resistance and extends the life of the contact, and is contained in the raw material mixture in a range of 20 to 70% by weight. When the content is less than 20 wt%, the arc resistance is lowered and it is difficult to extend the life of the contact. On the other hand, when the content exceeds 70% by weight, the content of Cu as a highly conductive component, which will be described later, is relatively lowered, and an energization function as a contact is lowered due to an increase in contact resistance.

  Further, Cu as a highly conductive component has a high conductivity, and is contained in an amount of about 80 to 30% by weight (wt%) as a remaining component excluding the Cr component in order to lower the contact resistance value of the contact. When the Cu content is less than 20% by weight, the conductivity is lowered, the contact resistance is increased, and the function as a contact material is lowered. On the other hand, when the content exceeds 80% by weight, the content of the arc-proof component is relatively reduced, and the contact is easily welded by an arc (electric arc) generated at the time of the contact opening / closing operation. End up.

The manufacturing method of the contact material for a vacuum circuit breaker used in the present invention is obtained by melting and dispersing a Cu—Cr material composed of Cu as a highly conductive component and Cr as an arc resistant component, and further quenching to obtain a Cu—Cr alloy powder. A step of preparing, a step of heat-treating the obtained Cu-Cr alloy powder at a temperature of 800 ° C or higher and 1080 ° C or lower to separate Cu and Cr into two phases, and from the heat treatment temperature to a temperature of 500 ° C or higher and 700 ° C or lower. The step of cooling in 30 minutes or more, the step of pressure-forming the cooled Cu-Cr alloy powder to form a Cu-Cr molded body, and the Cu-Cr molded body at a temperature of 900 ° C to 1080 ° C. forming a Cu-Cr sintered body was heated baking is preferably provided with a.

  In the heat treatment step, the Cu—Cr alloy powder is heat-treated at a temperature of 800 ° C. or higher and 1080 ° C. or lower to separate Cu and Cr into two phases, thereby precipitating Cr in a supersaturated solid state in the Cu phase, and further performing the heat treatment. By gradually cooling over 30 minutes or more from temperature to 500 to 700 ° C., the solid solution concentration of Cr in the Cu phase can be reduced to 200 ppm or less.

  In the step of preparing a Cu—Cr alloy powder by melting and dispersing a Cu—Cr material and quenching, it is preferable to use any one of an atomizing method, a rotating electrode method, and a centrifugal spraying method.

  Examples of the atomizing method include a water atomizing method, a gas atomizing method, and a vacuum atomizing method, and the gas atomizing method is most widely used for mass production. In this gas atomization method, first, a Cu—Cr material piece is melted and refined in an electric furnace, and this molten metal is discharged from a nozzle. Next, nitrogen, argon or air is blown against the molten metal stream to disperse and quench the molten metal to obtain a Cu—Cr alloy powder. The alloy powder produced in this way is spherical and thus has excellent fluidity and is easy to control the particle size and particle shape.

  In the rotating electrode method, a Cu—Cr alloy rod having the material composition of the alloy powder to be produced is mounted on the consumed rotating electrode as one electrode rod, and is rotated at high speed while being energized and heated in a high vacuum. The other end of the rotating electrode is a W (tungsten) electrode. When the electrode rod made of Cu—Cr alloy approaches the W electrode, an arc is generated, and the tip of the electrode rod made of Cu—Cr alloy is caused by the heat of the arc. It melts and scatters by rotation, and rapidly solidifies before the molten metal falls into the tank to form a Cu—Cr alloy powder. Since the tank is filled with He, there is no fear of oxidation and a high-purity powder can be obtained. Moreover, the powder produced in this way has the above impurities sufficiently reduced and has little composition segregation. The composition of the Cu—Cr alloy powder can be easily controlled by changing the mixing ratio of Cu and Cr at the time of producing the electrode rod.

  On the other hand, the centrifugal spraying method is a method of preparing a raw material powder having a predetermined composition by subdividing a molten metal into various droplets by various mechanical means and dispersing them in a gas phase and cooling them. Specifically, a Cu-Cr alloy powder is produced by spraying a molten Cu and Cr onto a rotating drum, cooling the molten metal, and simultaneously dispersing and quenching using centrifugal force. According to this centrifugal spraying method, droplets having a particle size in the range of 50 to 100 μm are generated. According to the above method, since the cooling time is extremely short, by producing sufficiently fine dispersed particles, it is possible to obtain multi-component fine particles such as Cu—Cr based particles having little segregation and a uniform composition. Further, the composition of the fine particles can be precisely controlled over a wide range, and the diameter, form, structure, etc. of the fine particles can be controlled according to the operating conditions. Furthermore, since the preparation temperature is relatively low, there is little reaction with the spray device wall, and a high purity alloy powder can be obtained. Therefore, this method is excellent as a precision preparation method for multi-component fine particles such as Cu—Cr.

  Next, in the step of forming the Cu—Cr alloy powder prepared by any of the atomizing method, the rotating electrode method, and the centrifugal spraying method, the alloy powder is filled in a die of a press molding machine and pressed with a predetermined pressure. A Cu-Cr molded body having a predetermined shape is obtained by molding. In particular, in the present invention, since the solid solution concentration of Cr in the Cu phase is reduced, and a soft Cu-Cr alloy powder having good formability is used, even when it is molded at a low pressure of 980 MPa or less, it is high. A Cu-Cr molded body having a density is obtained. Here, in order to obtain a Cu-Cr molded body having a predetermined shape by press molding with a pressing force of 980 MPa or more, a press machine that can withstand high pressure is required, and equipment that cannot be handled by a general-purpose machine. Subject to certain restrictions. In addition, since the mold is likely to be worn and damaged, maintenance is difficult, and mass production is substantially difficult, it is preferable to mold with a pressure of 980 MPa or less.

  The contact material for a vacuum circuit breaker according to the present invention is manufactured, for example, by the following procedure. First, a Cu—Cr material having a Cr content in the range of 30 to 70% by weight is melt-dispersed by the atomizing method, rotating electrode method or centrifugal spraying method, and further rapidly cooled to obtain a Cu—Cr alloy powder. The obtained Cu—Cr alloy powder was heat treated at a temperature of 800 ° C. or higher and 1080 ° C. or lower to separate Cu and Cr into two phases, and then the temperature from the heat treatment temperature to 500 ° C. or higher and 700 ° C. or lower was 30 minutes or longer. Cool gradually over time. The Cu—Cr alloy powder thus prepared is filled in a die of a press molding machine, press-molded with a pressure of 980 MPa or less to prepare a Cu—Cr molded body having a predetermined shape, and the obtained molding A Cu—Cr sintered body is formed by sintering the body in a non-oxidizing atmosphere such as a hydrogen atmosphere at a temperature of 900 to 1080 ° C. for 0.5 to 3 hours.

  The Cu—Cr sintered body formed in this way is processed into a predetermined shape to form a contact (contact member), and this contact is used with brazing material on the end faces of the opposing electrodes as shown in FIGS. Then, the vacuum circuit breaker is formed by joining the electrodes integrally joined to each other and joining the electrodes joined to the end portions of the conductive rods.

According to the Cu—Cr alloy powder used in the present invention and the contact material for a vacuum circuit breaker using the same according to the present invention, it is composed of Cu as a highly conductive component and Cr as an arc resistant component, and Cr in the Cu phase Since the solid solution concentration is 200 ppm or less, the hardness of the raw material powder is low, it is possible to reduce the molding pressure required at the time of molding, and there are equipment limitations such as the use of a general-purpose inexpensive molding machine. Alleviated. In addition, since the molding pressure is low, the molding die is less likely to be worn or damaged, and a manufacturing process with excellent mass productivity can be realized.

  Next, embodiments of the present invention will be described with reference to the following examples.

[Example 1]
As shown in Table 1, a Cu—Cr material having a Cu / Cr content ratio of 50:50 wt% was melted in an electric furnace and then scoured. Next, molten Cu and Cr were allowed to flow out of the nozzle, and nitrogen was blown against the molten metal stream to disperse and cool the molten metal, thereby obtaining a Cu—Cr alloy powder.

  Next, the obtained Cu—Cr alloy powder was heat-treated at a temperature of 1000 ° C. to separate Cu and Cr into two phases, and then cooled from the heat treatment temperature to 600 ° C. over 40 minutes. The Cu—Cr alloy powder thus prepared is filled into a die of a press molding machine, and press-molded at a pressure of 780 MPa so that the relative density of the contact material finally obtained is 94%. A shaped Cu—Cr compact was prepared, and the resulting compact was sintered in a hydrogen atmosphere at a temperature of 1000 ° C. for 3 hours to form a Cu—Cr sintered compact.

  Next, this Cu—Cr sintered body is processed into a predetermined shape to form contacts (contact members) 13a and 13b shown in FIGS. 1 and 2, and the brazing material 14 is attached to the end faces of the electrodes 7 and 8 facing each other. In addition, the electrodes 7 and 8 having the contacts 13a and 13b joined to each other are joined to the ends of the conductive rods 5 and 6 in the vacuum valve, whereby the vacuum circuit breaker according to the first embodiment is joined. Assembled.

[Example 2]
An alloy rod made of a Cu—Cr material with a Cu: Cr content ratio of 50:50 wt% was used as a consumable rotating electrode, and was rotated at high speed while energized and heated in a high vacuum. In other words, a W (tungsten) electrode is arranged at one end of the electrode, the Cu—Cr electrode rod is brought close to the W electrode, and the droplet from which the tip of the electrode rod of the Cu—Cr material is melted by the arc is dispersed by rotation. It was. Thereafter, the dispersed droplets were dropped into a tank filled with He to rapidly cool and solidify to obtain a Cu—Cr alloy powder.

  The obtained Cu—Cr alloy powder was heat treated at a temperature of 1000 ° C. to separate Cu and Cr into two phases, and then cooled from the heat treatment temperature to 600 ° C. over 40 minutes. The Cu—Cr alloy powder thus prepared is filled into a die of a press molding machine, and press-molded at a pressure of 780 MPa so that the relative density of the contact material finally obtained is 94%. A shaped Cu—Cr compact was prepared, and the resulting compact was sintered in a hydrogen atmosphere at a temperature of 1000 ° C. for 3 hours to form a Cu—Cr sintered compact.

  Next, this Cu—Cr sintered body is processed into a predetermined shape to form contacts (contact members) 13a and 13b shown in FIGS. 1 and 2, and the brazing material 14 is attached to the end faces of the electrodes 7 and 8 facing each other. Are joined together, and the electrodes 7 and 8 to which the contacts 13a and 13b are joined are joined to the ends of the conductive rods 5 and 6 in the vacuum valve, whereby the vacuum circuit breaker according to the second embodiment. Assembled.

[Example 3]
A Cu—Cr alloy molten metal having a Cu / Cr content ratio of 50: 50% by weight is sprayed on a rotating body (rotating drum) and dispersed, and at the same time, the centrifugal force is used to fly around and cool the Cu—Cr alloy. Cr alloy powder was used.

  The obtained Cu—Cr alloy powder was heat treated at a temperature of 1000 ° C. to separate Cu and Cr into two phases, and then cooled from the heat treatment temperature to 600 ° C. over 40 minutes. The Cu—Cr alloy powder thus prepared is filled into a die of a press molding machine, and press-molded at a pressure of 780 MPa so that the relative density of the contact material finally obtained is 94%. A shaped Cu—Cr compact was prepared, and the resulting compact was sintered in a hydrogen atmosphere at a temperature of 1000 ° C. for 3 hours to form a Cu—Cr sintered compact.

  Next, this Cu—Cr sintered body is processed into a predetermined shape to form contacts (contact members) 13a and 13b shown in FIGS. 1 and 2, and the brazing material 14 is attached to the end faces of the electrodes 7 and 8 facing each other. Are joined together, and the electrodes 7 and 8 to which the contacts 13a and 13b are joined, respectively, are joined to the ends of the conductive rods 5 and 6 in the vacuum valve, whereby the vacuum circuit breaker according to the third embodiment. Assembled.

[Comparative Example 1]
Cu-Cr alloy powder was prepared by treating the Cu-50% Cr material by the atomizing method in the same manner as in Example 1. Next, without carrying out the heat treatment after the atomizing treatment, the Cu—Cr alloy powder obtained by the rapid cooling treatment is filled in a press molding machine as it is, and thereafter molded and sintered under the same conditions as in Example 1 for comparison. A Cu—Cr sintered body according to No. 1 was prepared. Moreover, the obtained Cu-Cr sintered body was processed into a contact, and a vacuum circuit breaker according to Comparative Example 1 was assembled using the contact.

  In the vacuum circuit breaker according to each of the above examples, the relative density of the contact material (contactor) was high, the conductivity was good, and an excellent breaking characteristic was obtained. On the other hand, in the circuit breaker of the comparative example, since the hardness of the Cu—Cr alloy powder obtained by the rapid cooling treatment was high and the formability was poor, the mass productivity deteriorated.

In addition, in order to compare and evaluate the formability of each contact material, in Example 1, Example 2, Example 3, and Comparative Example 1, the molding pressure required to obtain the Cu—Cr molded body and the Cu phase were fixed. The solid solution concentration of melted Cr and the hardness of the Cu—Cr alloy powder were measured, and the results shown in Table 1 below were obtained.

  As is clear from the results shown in Table 1, after obtaining the Cu—Cr alloy powder using the atomizing method according to Example 1, the rotating electrode method according to Example 2, and the centrifugal spraying method according to Example 3, In the contact member manufactured by heat treatment and subjected to the cooling treatment, compared with the contact member of Comparative Example 1 manufactured without obtaining the powder by the atomizing method and then passing through the heat treatment step, the contact member is particularly solid in the Cu phase. The solid solution concentration of Cr to be melted is reduced, and in any case, the solid solution concentration of Cr is 20 ppm or less.

  From this, the Cu-Cr alloy powder obtained by the atomizing method, the rotating electrode method, and the centrifugal spraying method is heat-treated and then cooled, so that Cr dissolved in the Cu phase is precipitated and separated into two phases. The amount of Cr dissolved in the Cu phase can be effectively reduced. Therefore, the hardness of the Cu—Cr alloy powder is low, and can be press-molded at a pressure lower than that of Comparative Example 1, in fact, a pressurizing force of 980 MPa or less, and a contact material for a vacuum circuit breaker having good moldability is obtained .

Sectional drawing which shows the structure of the vacuum circuit breaker to which the contact material which concerns on this invention is applied. Sectional drawing which expands and shows the contact and electrode part shown in FIG.

1 Shut-off room 2 Insulation container (vacuum container, vacuum valve)
3a, 3b Sealing metal 4a, 4b Lid 5 Conductive bar 6 Conductive bar 7 Electrode (fixed electrode)
8 electrodes (movable electrodes)
9 Bellows 10 Arc shield 11 Arc shield 12 Brazing portion 13a, 13b Contact member 14 Brazing material (Ag brazing material)

Claims (4)

A step of preparing a Cu-Cr alloy powder by melt-dispersing a Cu-Cr material composed of Cu as a highly conductive component and Cr as an arc-resistant component, and further rapidly cooling ;
Heat-treating the obtained Cu—Cr alloy powder at a temperature of 800 ° C. or higher and 1080 ° C. or lower to separate Cu and Cr into two phases;
Cooling the heat treatment temperature from 500 ° C. to 700 ° C. over a period of 30 minutes or more;
Produced by solid-solution concentration of Cr in the Cu phase Ri der 20 ppm or less, vacuum breaker Vickers hardness, characterized in that the Cu-Cr alloy powder is less than 60Hv produced by press molding Contact material . The contact material for a vacuum circuit breaker according to claim 1,
  A contact material for a vacuum circuit breaker, wherein the Cu-Cr alloy powder has a Vickers hardness of 55 Hv to 60 Hv. The contact material for a vacuum circuit breaker according to claim 1,
A contact material for a vacuum circuit breaker, wherein the Cr content of the Cu-Cr alloy powder is in the range of 20 to 70% by weight. The contact material for a vacuum circuit breaker according to claim 1 ,
A contact material for a vacuum circuit breaker, which is produced by a step of heat- sintering a molded body obtained by pressure-molding the Cu-Cr alloy powder at a temperature of 900 ° C to 1080 ° C.

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