JP3251779B2 - Manufacturing method of contact material for vacuum valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art The basic characteristics required for the contacts of a vacuum valve are welding resistance, withstand voltage and high breaking performance. However, these three requirements require conflicting physical properties, making it difficult to make them ideally compatible. Therefore, the priority requirement of the circuit to be applied is first, and the other requirements are slightly sacrificed. The current situation is to deal with it.

[0003] For example, conventionally, in a high-withstand-pressure, large-capacity vacuum circuit breaker, an anti-weld- ing component (Bi, Te, Pb, etc.) is used.
It is known that a Cu alloy containing not more than% by weight is provided as an electrode contact.

However, with respect to recent demands for higher voltage, the withstand voltage is not sufficient. In other words, the vacuum circuit breaker has features that are superior to other circuit breakers, such as small size, light weight, maintenance-free, and environmental friendliness.
Since the application to circuits having a voltage lower than V has been increased, and the demand for opening and closing special circuits, for example, capacitor circuits, has been rapidly increasing, it is necessary to further increase the withstand voltage.

[0005] One of the important factors hindering the achievement is a restriking phenomenon and a re-arcing phenomenon. Although the restriking phenomenon is regarded as important from the viewpoint of improving the reliability of products, not only its prevention technology but also its direct cause has not yet been clarified.

[0006] With the increase in the withstand voltage, the contact material is required to have a higher withstand voltage and a characteristic in which a re-ignition phenomenon occurs less frequently. In order to achieve high withstand voltage and no re-ignition of the contact material, minimize the amount of the fragile anti-welding component itself, which is a defect in pressure resistance, avoid excessive concentration, and avoid gas impurities and pins. It is desirable to minimize holes and the like and to increase the strength of the contact alloy itself.

[0007] From these viewpoints, the above-mentioned Cu-Bi alloy is not satisfactory. Further, although the conventionally used Cu-W contact is considerably excellent in the withstand voltage, this sintered contact alloy is liable to have air bubbles remaining due to the production method and contains a welding prevention material. Therefore, there is a disadvantage that the re-ignition phenomenon easily occurs.

By the way, it is known that the frequency of occurrence of such a re-ignition phenomenon can be reduced to some extent by maintaining the heated state after the infiltration operation. However, by holding the contacts in such a heated state,
Generally, the loss of the welding prevention material having a high vapor pressure is lost, so that not only the welding resistance is reduced, but also the economic loss accompanying the loss of the expensive welding prevention material is large.

The present inventors have conducted detailed studies on the total amount of gas released and the form of release in the process of heating the contact material. These factors and the occurrence of restriking are important. The release of these gases, especially for each of the raw materials that make up the contact material,
In particular, it has been found that the re-ignition phenomenon can be effectively suppressed by controlling the release of gas suddenly generated near the melting point.

That is, as the contact material is heated, most of the adsorbed gas is degassed below the melting point and a solid-dissolved gas is released in the vicinity of the melting point. For a very short time (for example, on the order of several milliseconds), a pulsative gas release (several to hundreds of bursts) is observed.

[0011] These abrupt gases contain a small amount of C ₂ H ₂ , CH _4, etc., but since these are mainly composed of oxygen, such as CO, CO ₂ , O ₂ , these abrupt gases are contained in the contact material. It is considered to be released by decomposition of the oxides.

According to the study of the present inventors, contact materials in which re-ignition occurs frequently emit a large amount of sudden gas.
Therefore, according to the above findings, it is conceivable to prevent the re-ignition phenomenon by maintaining the contact material at a temperature equal to or higher than its melting point and releasing the sudden gas factor in advance.

However, the contact material for a vacuum valve is
In order to contain a considerable amount of Cu and to decompose and remove these oxides, for example, at a vacuum degree of 10 ^-2 to 10 ^-4 Torr, about 1200
Temperatures above ℃ are required. For this reason, B having a high vapor pressure
Performing the above-described heat treatment on a contact material containing a welding prevention material such as i, Pb, Te, or Sb causes loss of an expensive welding prevention material and is one of the basic functions of the contact material. The welding prevention performance is lost.

On the other hand, when Bi, for example, is heated as a welding prevention material, a plurality of types of gases are released very violently at around 400 to 500 ° C. Some of these released gases combine with Cu etc. in the process of raising the temperature to form a relatively stable compound, and some decompose during the melting operation, but others remain and remain sudden. Contributes to gas.

Even when Bi having a purity of 99.9999% is used as a raw material, such a burst of gas is still recognized when oxidation or gas adsorption is allowed to proceed.

The observation described above is based on the premise that, in a contact material containing a welding prevention material, impurities which cause a sudden gas are removed in advance by a heat treatment separately for a highly conductive material such as Cu and a welding prevention component. And the need to control the contamination of the contact alloy by the outgassed gases from crucibles, boats, plates, etc. during the manufacturing or heat treatment of the contact alloy.

Based on the former knowledge, the present inventors have developed a technique for individually heat-treating the constituent elements in advance in order to reduce the sudden gas, and to a certain extent, the tendency for the re-ignition occurrence probability to be reduced accordingly. I admit that there is.

Based on the latter finding, the present inventors have found that the material of the crucible, boat, plate and the like near the contact alloy at the time of melting or sintering and the physical and chemical state of its surface are changed to the form of sudden gas release. The authors acknowledge that this has a significant effect and, as a result, tends to be related to the magnitude of the probability of restriking occurring.

In particular, it has been recognized that the effect of reducing the sudden gas emission by controlling the contact alloy at the elemental level by the former technique can be surely and efficiently improved by overlapping with the latter technique.

Furthermore, it has been found that the amount of sudden gas in the total amount of gas contained in the contact alloy also affects the frequency of restriking. Since the sudden gas is actually released in a short time of about several milliseconds, it takes time and effort to measure the amount. Therefore, as described above, it is convenient to control by the ratio of the amount of the sudden gas obtained under certain conditions such as a predetermined temperature in the contact alloy, and the correlation with the frequency of restriking has been confirmed.

In the production or heat treatment of a contact alloy, it is necessary to minimize the generation of a burst of gas. However, since it is technically difficult to make this exactly zero, the occurrence of restriking is recognized. The upper limit of the amount of the sudden gas may be limited to the limit.

For the above-described reasons, in order to reduce, for example, oxygen gas which forms a solid solution or adsorbs on the contact material, the production or heat treatment of the contact material for the vacuum valve is performed by increasing the temperature up to the target heat treatment temperature and then performing the heat treatment. The sintering and infiltration operation at a constant temperature is generally performed in a vacuum. As a result, it is almost 1 in comparison with the case where the atmosphere is not controlled.
It is practically used because it is as light as / 10 to 1/1000. When the process is performed in hydrogen, the remaining hydrogen gas increases in vacuum, but the same tendency is observed from the viewpoint of reducing oxygen gas.

[0023]

As described above, conventionally, the amount of gas is reduced by setting the heat treatment atmosphere from the temperature raising operation to the sintering and infiltration operations in a vacuum or in hydrogen. This level of gas amount is not sufficient for recent demands for higher voltage and higher current, and for suppressing sudden gas that is useful for reducing the frequency of restriking, the heat treatment atmosphere must be used. No consideration was given to selection.
An object of the present invention is to provide a method for manufacturing a contact material for a vacuum valve, which can reduce the frequency of occurrence of restriking while maintaining high current interruption performance.

[0024]

In order to achieve the above-mentioned object, the present invention provides a heat-treated object comprising a highly conductive component comprising at least one of Cu or Ag and an arc-resistant component comprising Cr. A first step of heating to a predetermined heat treatment temperature, a second step of holding at the heat treatment temperature for a predetermined time, and a third step of cooling after holding for a predetermined time;
The gist is that the atmosphere in the second step or the third step is selected and the heat treatment atmosphere is switched to a desired atmosphere without lowering the heat treatment temperature.

[0025]

In such a configuration, the effect of first performing the heat treatment on the object to be heat-treated in a vacuum atmosphere at the beginning of the heat treatment, that is, (step I) or (step I) and (step II), is as follows. And various gases (oxygen, nitrogen, etc.) loosely but adsorbed and adsorbed in large amounts in gaps between constituent particles
And quickly and reliably remove most of the water. On the other hand, when the first heat treatment is performed in a hydrogen atmosphere, it is not only difficult to remove a large amount of various gases and moisture in a short time, but also gas and moisture may remain particularly in gaps between constituent particles. This is disadvantageous for the production of a contact material with a reduced gas level, especially a reduced amount of bursty gas. This makes it difficult to provide a highly reliable vacuum valve that reduces the frequency of restriking while maintaining the desired high current interruption performance.

Next, the second half of the heat treatment, that is, (Step II)
Alternatively, the effect of performing the cooling treatment or the heating treatment and the cooling treatment on the heat-treated body in the hydrogen atmosphere in the (step II) and the (step III) is based on the structure of the heat-treated body that could not be removed by the heat treatment in the vacuum atmosphere. It decomposes and removes (reduces oxides) the gas, deposits and coatings still remaining in the details between the particles. On the other hand, when the second half of the heat treatment is performed in a vacuum atmosphere, not only the above effect is not obtained but also the cooling rate of the heat treatment object is reduced, and as a result, shrinkage holes inside the heat treatment object are generated together with reduced economic efficiency. It encourages and hinders obtaining a healthy contact material.

The effect of switching the heat treatment atmosphere from a vacuum atmosphere to a hydrogen atmosphere without lowering the heat treatment temperature is as follows.
In general, no matter how well the industrial heat treatment furnace is managed, it is impossible to prevent gas from leaking from the ingress furnace wall and the like. When the temperature of the heat treatment furnace is cooled, these gases are re-adsorbed on the furnace inner surface such as the furnace wall and serve as a gas supply source. When the object to be heat treated which has been subjected to the heat treatment in the vacuum atmosphere is placed in such an atmosphere, a phenomenon of reattachment and re-invasion of gas also occurs in the object to be heat treated. Therefore, in order to avoid this phenomenon, it is advantageous to switch the atmosphere without cooling the object to be heat-treated.

[0028]

An embodiment of the present invention will be described below with reference to the drawings. In this embodiment, the material used for the arc area, that is, the contact, and if necessary, the electrode, the conductive shaft,
As a material for the shield or the like, a material in which the total amount of the burst gas released under a heating state at least 50 ° C. higher than its melting point is less than 1% of the total gas amount in the material is used.

FIG. 1 is a front sectional view of a vacuum valve showing an embodiment of the present invention, and FIG. 2 is an enlarged view of a main part thereof. In these figures, a shut-off chamber 1 is composed of an insulating container 2 formed of an insulating material such as ceramic in a substantially cylindrical shape, and metal lids 4 and 5 provided at both ends thereof through sealing mechanisms 3 and 3a. It is hermetically sealed in a vacuum.

Further, in the shut-off chamber 1, a fixed electrode 8 and a movable electrode 9 are disposed at opposite ends of a pair of electrode rods 6, 7, respectively. A bellows 10 is attached to the electrode rod 7 of the movable electrode 9 so that the pair of electrodes 8, 9 can be opened and closed by reciprocating movement of the electrode 9 while keeping the inside of the shut-off chamber 1 vacuum-tight.

The bellows 10 is covered by a hood 11 to prevent the deposition of arc vapor. A cylindrical metal container 12 is provided in the shutoff chamber 1, and the deposition of arc vapor to the insulating container 2 is performed. Preventing.

On the other hand, as shown in FIG. 2, the movable electrode 9 is fixed to the conductive rod 7 by a brazing material 13 or is connected by crimping (not shown) by caulking. Are joined by the brazing material 15.

The fixed electrode 8 is almost the same except that the direction is reversed. The fixed electrode 8 is provided with a fixed contact 14a. The material used for manufacturing the material used in this embodiment is not different from the conventional one.

For example, the electrode or the conductive shaft is made of copper or a copper alloy made of oxygen-free copper, deoxidized copper, electrolytic copper or the like, and the contact alloy is made of the above copper, silver or both.
The maximum value is the amount obtained by subtracting the amount of the anti-welding material in the contact alloy, and the minimum value is 15% or more from the viewpoint of conductivity.

As the welding prevention material, Bi, Pb,
At least one of Te and Sb is used, and these anti-welding materials are used in accordance with the degree of anti-welding required for the contact alloy.
The amount is used in the range of 5%.

In the implementation of the manufacturing technique of the present embodiment, a crucible or a container in a well-controlled state is used to prevent the intrusion and diffusion of impurities and gases from the crucible or the like into the contact material, and The point is to remove factors that may cause gas generation. In that sense, degassing a crucible or the like under predetermined conditions in advance
Useful as an assistive technology.

In addition to managing the state of the crucible and the like,
The selection of the material is also useful as an auxiliary technology for reducing the sudden gas. By combining this technology and assistive technology,
A contact material with less sudden gas is obtained. A contact having a desired shape can be obtained by subjecting the obtained contact material to processing such as cutting and polishing as necessary, or applying plastic processing such as forging rolling as necessary.

The evaluation of the contact material was performed based on two conditions, which will be described later, ie, sudden gas release and re-ignition probability. An example of obtaining the contact alloy used in the most severe arc region among the materials used in the present embodiment is as follows. Hereinafter, with reference to Tables 1 and 2, a more specific description will be given by a sample test.

[0039]

[Table 1]

[0040]

[Table 2]

Examples: 1-2, Comparative Examples: 1-3 (Example: 1) Cu purified at a temperature of 1300 ° C. or more, 13
Using Cr degassed at a temperature of 00 ° C. or more as a raw material, Cu,
Cr powder was mixed and molded at 4 tons / cm ² to obtain a heat-treated body.

After raising the temperature in a vacuum atmosphere (step I), solid phase sintering at 1000 ° C. in a vacuum atmosphere (step II), the atmosphere is switched to a hydrogen atmosphere at this temperature and cooled in a hydrogen atmosphere (step III).
A Cu-25Cr contact material was manufactured. (Comparative Example: 1) In the same manner as in the above (Example: 1), Cu and Cr powder were mixed using Cu purified at a temperature of 1300 ° C. or more and Cr degassed at a temperature of 1300 ° C. or more as raw materials, and 4 tons. /cm
^The heat-treated body was obtained by molding in ² .

After raising the temperature in a vacuum atmosphere (Step I), solid-phase sintering at 1000 ° C. in a vacuum atmosphere (Step II), and cooling it to about 500 ° C. in a vacuum atmosphere (Step III), Switch to atmosphere and cool to room temperature (Step III).
A 25Cr contact material was manufactured. (Comparative Example: 2) In the above (Example 1), after raising the temperature in a vacuum atmosphere (Step I), solid-phase sintering at 1000 ° C. in a vacuum atmosphere (Step II), and then directly room temperature in a vacuum atmosphere (Step III) to produce a contact material. (Comparative Example: 3) In the same manner as in the above (Example: 1), Cu and Cr powders were mixed using Cu purified at a temperature of 1300 ° C. or higher and Cr degassed at a temperature of 1300 ° C. or higher as raw materials, and 4 tons. /cm
^The heat-treated body was obtained by molding in ² .

After raising the temperature in a hydrogen atmosphere (step I) and solid-phase sintering at 1000 ° C. in a hydrogen atmosphere (step II), it is cooled to room temperature in a hydrogen atmosphere (step III) to obtain Cu-25C
An r-contact material was manufactured. (Example: 2) Similar to the above (Example: 1), Cu and Cr powders were mixed using Cu refined at a temperature of 1300 ° C. or higher and Cr degassed at a temperature of 1300 ° C. or higher as raw materials, and 4 tons. /cm
^The heat-treated body was obtained by molding in ² .

The temperature was raised in a vacuum atmosphere (step I), solid phase sintering was performed at 1000 ° C. in a hydrogen atmosphere (step II), and then switched to a hydrogen atmosphere at this temperature and cooled in a hydrogen atmosphere (step III).
A Cu-25Cr contact material was manufactured.

Example: 3-4, Comparative Example: 4-5 (Example: 3) In the same manner as in the above (Example: 1), Cu purified at a temperature of 1300 ° C. or more was removed from Cu at a temperature of 1300 ° C. or more. A gaseous Cr powder is prepared.

The temperature of the Cr powder was raised in a vacuum atmosphere (step I) while the Cr skeleton obtained by sintering the Cr powder at a temperature of 1150 ° C. or higher and Cu at a temperature of 1170 ° C. The molten Cu was vacuum infiltrated into the voids of the Cr skeleton (Step II), switched to a hydrogen atmosphere at this temperature, and cooled in a hydrogen atmosphere (Step III) to produce a Cu-25Cr contact material. (Comparative Example: 4) Similar to the above (Example: 1), Cu purified at a temperature of 1300 ° C. or higher and Cr powder degassed at a temperature of 1300 ° C. or higher are prepared.

The temperature of the Cr skeleton obtained by sintering the Cr powder at a temperature of 1150 ° C. or higher in a vacuum atmosphere and Cu is superimposed in a vacuum atmosphere while superimposing the Cu (step I), and the temperature is maintained at 1170 ° C. The molten Cu was vacuum infiltrated into the voids of the Cr skeleton (Step II) and then cooled to room temperature in a vacuum atmosphere (Step III) to produce a Cu-25Cr contact material. (Comparative Example: 5) Similar to the above (Example 1), Cu purified at a temperature of 1300 ° C. or more and Cr powder degassed at a temperature of 1300 ° C. or more are prepared.

The Cr skeleton obtained by sintering the Cr powder at a temperature of 1150 ° C. or more in a vacuum atmosphere and Cu are superimposed, and the temperature is raised in a vacuum atmosphere (step I) while being kept at 1170 ° C. The molten Cu was infiltrated in a hydrogen atmosphere in the voids of the Cr skeleton (Step II) and cooled in a hydrogen atmosphere (Step III) to produce a Cu-25Cr contact material. (Example 4) Similar to the above (Example 1), Cu purified at a temperature of 1300 ° C. or more and Cr powder degassed at a temperature of 1300 ° C. or more are prepared.

The temperature of the Cr powder was raised in a vacuum atmosphere (step I) while the Cr skeleton obtained by sintering the Cr powder at a temperature of 1150 ° C. or higher and Cu at a temperature of 1170 ° C. The molten Cu was infiltrated in a hydrogen atmosphere in the voids of the Cr skeleton (Step II) and cooled in a hydrogen atmosphere (Step III) to produce a Cu-25Cr contact material.

As is clear from Examples 1 to 4 and Comparative Examples 1 to 5, the heating (step I) and the heating and holding (step II) are performed in a vacuum atmosphere, the cooling (step III) is performed in a hydrogen atmosphere, and The effect is exhibited by switching the atmosphere at a high heating and holding temperature. As shown in Comparative Example 1, it was found that the effect was low if the atmosphere was switched after cooling the atmosphere to about 500 ° C. (Comparison between Example 1 and Comparative Example 1). Further, when the atmosphere is not switched, sufficient characteristics are not obtained (Comparative Examples: 2-3, Comparative Examples: 4-
5).

Examples 5 to 8 (Example 5) On the other hand, for a Cu-Cr-Bi alloy containing, for example, Bi as a welding prevention component, Bi purified at a temperature of 600 ° C. or higher is prepared as a raw material. Cu and Cr are the same as in the above (Example 1).

Cu, Cr and Bi powders are mixed and molded to obtain a heat-treated body, which is heated in a vacuum atmosphere (step I).
After solid phase sintering at 1000 ° C in a vacuum atmosphere (Step II), switch to hydrogen atmosphere at this temperature and cool in a hydrogen atmosphere (Step III)
Then, a Cu-50Cr-0.2 Bi contact material was manufactured. (Example 6) As in the above (Example 1), Bi purified at a temperature of 600 ° C. or higher is prepared as a raw material. Cu, C
r is the same as the above (Example 1).

After infiltrating CuBi into the Cr skeleton at 160 ° C. in a vacuum atmosphere (step II), the atmosphere is switched to a hydrogen atmosphere at this temperature and cooled and solidified in a hydrogen atmosphere (step III).
A Cu-25Cr-0.2 Bi contact material was manufactured.

As described above, the same effect is obtained with the Cu—Cr—Bi alloy (Examples: 5 to 6). Further, in Examples: 5 to 6, Cu-Cr-Bi alloys containing Bi as a welding prevention component were shown, but Cu-Cr-Te alloys containing Te as a welding prevention component other than Bi,
It is also effective for Cu-Cr-Sb alloy containing Sb.

For example, Te purified at a temperature of 600 ° C. or higher is prepared as a raw material. Cu and Cr are as described above (Example: 1)
Is the same as After infiltrating CuBi into the Cr skeleton at 1120 ° C. in a vacuum atmosphere (Step II), switch to a hydrogen atmosphere at this temperature and cool and solidify in a hydrogen atmosphere (Step III).
Then, a Cu-50Cr-4Te contact material was manufactured. Cu-
Almost the same effects as those of the Cu-Cr-Bi alloy are obtained in the Cr-Te alloy.

Further, in the case of Cu-Cr-Sb alloy containing Sb, Sb purified at a temperature of 600 ° C. or more is prepared as a raw material. Cu and Cr are the same as in the above (Example 1). After infiltrating CuSb into a Cr skeleton at 1100 ° C. in a vacuum atmosphere (Step II), the atmosphere is switched to a hydrogen atmosphere at this temperature and solidified by cooling in a hydrogen atmosphere (Step III),
A -50Cr-0.2Sb contact material was manufactured. Cu-Cr-
In the case of the Sb alloy, substantially the same effects as those of the Cu-Cr-Bi alloy are obtained. (Example: 7) Cu powder obtained by pulverizing Cu purified at a temperature of 1300 ° C. or more, and Cr degassed at a temperature of 1300 ° C. or more
Powder, and mix Cu and Cr powder, 4 tons / cm ²
To obtain a heat-treated body.

The object to be heat-treated is heated to a temperature of 950 ° C. in a vacuum atmosphere (step I), and heated and held at 950 ° C. (step II) to obtain a CuCr skeleton.
° C (Step I), and heat and hold again at 1200 ° C (Step I)
I) Then, the molten Cu was vacuum-infiltrated into the voids of the CuCr skeleton, and the atmosphere was switched to a hydrogen atmosphere at this temperature and cooled in a hydrogen atmosphere (step III) to produce a Cu-50Cr contact material. (Example 8) Cu powder obtained by pulverizing Cu purified at a temperature of 1300 ° C. or more, and Cr degassed at a temperature of 1300 ° C. or more
Powder, and mix Cu and Cr powder, 4 tons / cm ²
To obtain a heat-treated body.

The temperature of the object to be heat-treated is raised to a temperature of 1030 ° C. in a vacuum atmosphere (Step I), and while heating and holding at 1030 ° C. (Step II), the vacuum atmosphere is switched to a hydrogen atmosphere and cooled in a hydrogen atmosphere ( Step III) to produce a Cu-50Cr contact material.

As described above, an excellent effect was exhibited by repeating the cycle of raising the temperature (step I) and heating and holding (step II) a plurality of times (Example: 7). In addition, heat holding (process
Even if the atmosphere was switched during the course of II), an excellent effect was exhibited (Example: 8).

Examples 9 to 18 In Examples 1 to 8 and Comparative Examples 1 to 5 described above, Cu was used as a high conductivity component and Cr was used as a typical arc resistant component. -It can be applied without being limited to Cr, Cu-Cr-Bi. For example, Cr in Cu-Cr
Is partly W (Example-9), part of Cr is Mo (Example-10), part of Cr is Ti (Example-11), and part of Cr is Ta (Example-12). , Cr are partially replaced by Nb (Example-1).
It is also effective in the production of contacts replaced in 3).

Further, as arc-resistant components other than Cr, W, M
The same effect is exhibited in a Cu alloy in which o, Ti, Ta, and Nb are selected (Examples: 14 to 19). Further, in Examples 1 to 8 and Comparative Examples 1 to 5 described above, Cu was shown as a typical example as a highly conductive component. However, the method of the present invention is not limited to Cu. The same effect is exhibited even with Ag-WC using carbide as a component. (Regarding sample test) (a) Sudden gas release A sample cut from an ingot is placed in a vacuum device for measuring sudden gas release and heated at a constant rate from room temperature to a predetermined temperature exceeding the melting point (for example, Cu- 12 for Cr
50 ° C.), and the integrated value of the number of times of sudden release during standing for a certain period of time (for example, 30 minutes when Cu = Cr) is measured in a vacuum degree of 10 ⁻⁵ to 10 ⁻⁶ Torr. (B) Probability of re-ignition The frequency of re-ignition when a disc-shaped contact piece with a diameter of 30 mm and a thickness of 5 mm is mounted on a day mountable vacuum valve and a 6 KV x 500 A circuit is cut off 2000 times is shown. The measurement was made, and the variation width (maximum and minimum) of two circuit breakers (six valves) was shown.

At the time of mounting the contacts, only baking heating (450 ° C., 30 minutes) was performed, and the use of the brazing material and the accompanying heating were not performed. In addition, the total gas amount was the amount of gas released during holding at a high temperature of 1500 ° C. or higher for a predetermined time.

That is, the sample is accommodated in, for example, a carbon crucible held in a high vacuum, and the carbon crucible is directly energized or heated by a method such as high frequency heating.
Quantify the gas released from the sample.

[0065]

As described above, according to the present invention, since the atmosphere in each step of the manufacturing process is appropriately adjusted, it is possible to reduce the frequency of occurrence of restriking while maintaining high current interruption performance. it can.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a vacuum valve for explaining one embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

[Explanation of symbols]

 8: fixed electrode, 9: movable electrode, 14, 14a: contact

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshiko Minami 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Toshiba Corporation Yokohama Office (72) Inventor Atsushi Yamamoto 1 Toshiba-cho, Fuchu-shi, Tokyo Fuchu Toshiba Corporation Inside the factory (56) References JP-A-63-199833 (JP, A) JP-A-56-150155 (JP, A) JP-A-4-180546 (JP, A) JP-A-49-114609 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01H 33/66 C22C 1/00 H01H 11/04

Claims (8)

(57) [Claims] 1. A first step of heating an object to be heat-treated comprising a highly conductive component made of at least one of Cu or Ag and an arc-resistant component made of Cr to a predetermined heat treatment temperature; A second step of holding at a temperature for a predetermined time; and a third step of cooling after holding the predetermined time, wherein the first step is a vacuum atmosphere, the second step is a hydrogen atmosphere, and the heat treatment is performed. A method for manufacturing a contact material for a vacuum valve, wherein the heat treatment atmosphere is switched from a vacuum atmosphere to a hydrogen atmosphere without lowering the temperature. 2. The method according to claim 1, wherein the first and second steps are repeated a plurality of times. 3. A first step of heating an object to be heat-treated composed of a highly conductive component made of at least one of Cu or Ag and an arc-resistant component made of Cr to a predetermined heat treatment temperature; A second step of holding at a temperature for a predetermined time; and a third step of cooling after holding the predetermined time. The first step and the second step are performed in a vacuum atmosphere, and the third step is performed in a hydrogen atmosphere. A method for manufacturing a contact material for a vacuum valve, wherein the atmosphere is changed to an atmosphere and a heat treatment atmosphere is switched from a vacuum atmosphere to a hydrogen atmosphere without lowering the heat treatment temperature. 4. The heat treatment atmosphere is switched from a vacuum atmosphere to a hydrogen atmosphere without lowering the heat treatment temperature during the second step or the third step. A method for producing the contact material for a vacuum valve as described above. 5. The vacuum apparatus according to claim 1, wherein the switching from the vacuum atmosphere to the hydrogen atmosphere is performed by moving the heat treatment target to a hydrogen atmosphere chamber. Manufacturing method of valve contact material. 6. The vacuum valve according to claim 1, wherein the switching from the vacuum atmosphere to the hydrogen atmosphere is performed by injecting hydrogen into the vacuum atmosphere. Manufacturing method of contact material. 7. An arc-resistant component of the heat-treated body, wherein part or all of Cr is made of one of W, Mo, Ti, Ta and Nb. Item 6
The method for producing a contact material for a vacuum valve according to any one of the above. 8. The highly conductive component of the object to be heat-treated is Cu
, CuBi, CuTe, CuS containing 5 wt% or less of Cu, one of Bi, Te and Sb
The method for producing a contact material for a vacuum valve according to any one of claims 1 to 7, wherein the method is any one of (b) and (b).