JPH09213179A - Manufacture of vacuum bulb - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve joining performance and reduce lowering of operating characteristics and restrike characteristics by specifying heating/cooling speed in assembling. SOLUTION: In a heating process when the end part of an insulating container in which a pair of electrodes are arranged in such a state as freely contacted/separated with each other and a sealing metal which seals the insulating container with a lid body are joined together, they are heated at the temperature increase speed of 1-20 deg.C/min from work temperature of 600 deg.C to brazing. In a cooling process, they are cooled at the cooling speed of 0.5-30 deg.C/min from brazing work temperature to 400 deg.C. This process can optimize heating/cooling conditions in assembling and improve the joining performance of the end face of the insulating container with the sealing metal via a silver brazing material. Improving of joining strength after the joining treatment can reduce the lowering of the operation characteristics and restrike characteristics for a long period.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing a vacuum valve.

[0002]

2. Description of the Related Art Generally, a vacuum valve is constructed as follows. That is, for example, it has a ceramic insulating container (outer tube) formed of at least 90% purity aluminum oxide, etc., and inside it has a fixed electrode joined to the current-carrying shaft and the current-carrying shaft in the same way on the opposite side And a movable electrode which is joined to and is separable by a bellows. Both ends of this insulating container are vacuum-tightly sealed with a lid by sealing metal fittings to form a vacuum container. Further, when the electrodes are opened and closed to cut off the current, an arc composed of metal particles is formed between the contacts. This arc maintains the current at a low arc voltage and diffuses at high speed to the surroundings, but it is not preferable that the metal particles of the arc adhere to the inner surface of the insulating container,
An arc shield is provided around the electrodes and is joined to the mounting member of the insulating container.

In general, ceramics have excellent heat resistance, insulation, and airtightness, and are used as electrical component materials such as the insulating container of the above-mentioned vacuum valve by taking advantage of their characteristics.

Particularly, in the case of a ceramic outer tube of a vacuum valve, in order to maintain a vacuum inside, it is necessary to strictly maintain hermeticity for a long period of time. However, since the ceramics insulating container and the metal generally differ greatly in thermal expansion coefficient, thermal stress often occurs due to the difference in thermal expansion coefficient between the two. These thermal stresses tend to cause cracks in ceramics.
Therefore, in order to reduce the occurrence of such thermal stress, a joining method using a metal as close as possible to the coefficient of thermal expansion of ceramics has been studied. Examples of metals used for such purposes include iron-based alloys, particularly Invar-based alloys, Erinba-based alloys, or F alloys commonly called Kovar or 42 alloy.
Examples include iron-based low coefficient of thermal expansion alloys such as e-Ni-based and Fe-Ni-Co-based alloys.

By the way, when the ceramic insulating container and the sealing metal are joined via a silver brazing material, generally, the end face (surface) of the ceramic member is commonly called molybdenum.
Mo, W, Mn called manganese method (Mo-Mn method)
It is said that paste containing powder is applied in advance, high temperature heat treatment of 1400 ° C or more is performed in a humidified atmosphere to metallize the surface of the ceramic insulating container, and then Ni plating is performed and then a brazing material is used for bonding. Many expensive methods are used.

[0006]

By the way, recently, a method of combining a metal such as Ti, which is called an active metal, and a metallic silver brazing material such as silver brazing (Ag-Cu) has been attracting attention. This method uses IVA, V of the periodic table such as Ti and Zr.
Bonding is performed by utilizing the action of active metals such as group A having high reactivity with ceramics, and representative active metals include Ag-Cu-Ti, Ag-Cu-Zr, and Cu-Ti brazing materials. To be

By placing these active metal brazing materials in various states such as alloys and laminated bodies on the joint between metal and ceramics and heating them in a vacuum inert atmosphere, the two can be joined well. It can be done. According to this method, the melting points of these brazing materials are about 780 ° C. for Ag—Cu type and about 870 ° C. for Cu—Ti type, which are generally low. It is characterized in that it can be joined with and high joint strength can be obtained.

[0008] However, a plurality of randomly selected untreated ceramic insulating containers are used, and the iron-based low thermal expansion coefficient alloy (hereinafter referred to as iron-based alloy) is used as the sealing metal fitting. Even if the vacuum valve is used after being subjected to sufficient heat treatment for strain relief, some residual stress exists in the vicinity of the interface between the aluminum oxide ceramic insulating container and the sealing metal fitting. The main reason for this was the occurrence of irregularity and irregularity in airtightness and reignition.
From this, it was inferred that the state of the ceramic insulating container itself influences the airtightness and the occurrence of restriking in a variation phenomenon and an irregular occurrence. An object of the present invention is to provide a method of manufacturing a vacuum valve, which can improve the bondability and can reduce the deterioration of the breaking characteristic and the re-ignition characteristic over a long period of time.

[0009]

In order to achieve the above object, the present invention provides an end portion of an insulating container in which a pair of electrodes are arranged so that they can come into contact with and separate from each other, and a sealing for sealing the insulating container with a lid. A method of manufacturing a vacuum valve in which a brazing material is placed between the metal fittings and the insulating container and the metal fittings are hermetically sealed while exhausting the whole in a vacuum. 1 to
The gist of the present invention is to have a heating step of heating at a temperature rising rate of 20 ° C / min and a cooling step of cooling the brazing working temperature to 400 ° C at a cooling rate of 0.5 to 30 ° C / min.

In the vacuum circuit breaker, a phenomenon in which a flashover occurs in the vacuum valve after the current is cut off and the contacts are brought into a conductive state again (the discharge does not continue thereafter) is called re-ignition, and the mechanism of occurrence is unclear. However, an abnormal overvoltage is likely to occur because the electric circuit suddenly changes to the conductive state after the current is cut off. Particularly, according to an experiment in which re-ignition is generated when the capacitor bank is cut off, an extremely large overvoltage is generated and an excessive high-frequency current flows, so that suppression of re-ignition is required.

As described above, although the mechanism of occurrence of the re-ignition phenomenon is not yet known, according to the experiments and observations made by the present inventors, re-ignition is caused by the contact / contact between the vacuum valves and the contact / arc. It occurs quite frequently between shields. Therefore, the present inventors, for example, suppression of sudden gas emitted when the contact receives an arc, optimization of the contact surface morphology,
The technology that is extremely effective in suppressing the re-ignition has been clarified, and the number of re-ignitions has been significantly reduced. However, the recent demands for high withstand voltage, high current interruption, and miniaturization of vacuum valves are considered to be already limited by the improvement of the above contacts.
In addition to these, improvement optimization has become necessary.
That is, the inventors of the present invention appropriately seal or remove each component such as a ceramic insulating container outer tube, a contact, an arc shield, a metal lid, a current carrying shaft, a metal fitting, and a bellows into a vacuum valve. However, when a simulated re-ignition generation experiment was conducted, it was found that the condition of the ceramic insulating container is important, except for the contact and arc shield that receive the direct arc. Furthermore, when a vacuum valve was created by combining a plurality of ceramics insulating containers and the re-ignition occurrence situation was observed, after optimizing the contacts and contact materials, the ceramics insulating container with the largest surface area in the vacuum valve It has also been found to be beneficial to add an optimization of. In other words, as a result of detailed analysis, (a) the state of the end surface of the ceramic insulating container, (b) foreign matter such as gas or moisture that has adhered to, adsorbed on the surface of the ceramic insulating container, and has not been removed yet (c) ceramics It was found that the stress generated at the joint interface is involved due to the combination of and the sealing metal fitting.

As a result of the observation, in the state of the container end face of (a), the pre-finished surface roughness has an effect, and the re-ignition phenomenon occurs from the relatively early stage of the current interruption switching number. . In such a case, it was observed that the flow of the brazing material was hindered at the joining of the container end face and the sealing metal fitting. When the surface roughness is unsuitable, there are variations in the bonding strength after bonding and insufficient strength is observed.
Further, it has an unfavorable effect on the airtightness and the frequency of re-ignition.

On the other hand, a large amount of foreign matter on the surface of the ceramic container (b) was generated in the early to middle stages of the number of times of opening and closing the current.
In such a case, a black shadow appears on the ceramic surface. It was also found that they were already attached in the previous step in terms of quantity compared to the ones attached during the heat treatment during assembly. It was effective to give a heat treatment step of heat treatment to 800 ° C or more before use. According to the micro x-ray analysis, the foreign matter existing on the ceramic surface after this treatment was significantly reduced from that before the treatment.

Further, in the relationship of stress at the joint interface of (C),
It occurred in the comparatively latter half of the passage of the number of times of the current interruption, but the re-ignition phenomenon was observed when it was opened and closed even if it was left alone without giving the opening and closing action. In such a case, the development of microcracks was observed in the vicinity of the joint interface, although it was extremely fine. Some vacuum valves showed a vacuum leak depending on the number of times of interruption. By optimizing the heating and cooling conditions when assembling the vacuum valve,
There was a tendency to reduce the progress of microcracks.

From the above, the timing of occurrence of the re-ignition phenomenon appears to be irrelevant to the progress of the number of times of current interruption, but each occurrence occurs as in (a), (b) and (c) above. It turned out that the cause differs depending on the time. This was considered to be an important cause for the occurrence of the re-ignition phenomenon for each vacuum valve.

[0016] Therefore, according to the research conducted by the present inventors, in order to suppress or reduce all the timings of each occurrence of re-ignition, a heat treatment process should be applied to the insulating container in advance. After optimizing the end surface roughness of
It was found that what is important is to optimize the heating and cooling conditions when assembling the vacuum valve, and the present invention has been completed.

[0017]

Embodiments of the present invention will be described in detail above. The gist of the present invention is to attach a vacuum valve sealing metal fitting using an active metal brazing material to a ceramic insulating container in order to reduce the occurrence of re-ignition phenomenon of the vacuum valve in order to reduce the vacuum valve assembly process. In particular, the proper control is given to the air-tight sealing process and the proper control is given to the ceramic insulating container among the constituent members, and the effect is obtained by superposing these. Therefore, a series of management for the ceramic insulating container is an important point. The conditions for characteristic evaluation are shown.

(1) Breaking characteristics: An experimental valve for breaking test equipped with a 70 mm diameter contact manufactured under each of the above-mentioned conditions was attached to a switchgear, and after baking, voltage aging, etc., a circuit of 24 kv, 50 Hz Was connected to each other and the breaking limit was compared and evaluated for three vacuum valves while increasing the current by 1 kA. In addition, only the result of the first embodiment is the vacuum valve 3
The values are average values of the book, and other numerical values are shown with a range of variation when the value of Example 1 is set to 100. A leak test was performed on the experimental valve before and after the breaking test, and the experimental valve after the breaking test was destroyed, and the extent of arc spread was also observed to help judge the breaking performance.

(2) Re-ignition characteristics: Re-ignition when a disc-shaped contact piece having a diameter of 30 mm and a thickness of 5 mm is mounted on a demountable type vacuum valve and a circuit of 24 kV x 500 A is cut off 2000 times. The frequency of occurrence was displayed in consideration of the variation values of the two circuit breakers (six vacuum valves).

(3) Evaluation of silver brazing property: Visual observation of adhesion state of silver brazing and metallurgical microscope of joint interface on a part of the vacuum valve after the vacuum valve assembling process (silver brazing process). It was judged from the microscopic observation result by.

(Examples 1 to 5 and Comparative Examples 1 and 2) An insulating ceramics container (main component) having an outer diameter of 6.7 cm, an inner diameter of 5.6 cm, and a height of 10 cm, which was ground to have an average surface roughness of about 1.5 μm. : AL ₂ O ₃ ) was prepared. The ceramic insulating container was preheated at 1650 ° C before assembly.

As a sealing metal fitting, 42% Ni- with a plate thickness of 2 mm
An Fe alloy was prepared. As a brazing material containing an active metal, a 72% Ag-Cu-0.5% Ti alloy plate having a thickness of 0.1 mm was prepared. The brazing material containing the active metal used in this example can be carried out without being limited to this alloy plate, and the method of supplying the active metal includes, for example, a method of supplying Ti on the metal foil surface, That is, Ti melted or ionized by using an arc-melted Ti target as an active metal source and appropriately selecting or combining arc discharge, ion plating, electron impact, sputtering, etc. as a heating means.
To the surface of the metal foil (Cu foil). While controlling the implantation energy for vaporizing or ionizing, the average particle diameter of Ti particles on the metal foil surface is, for example, 0.01 to 20.
The range of μm may be set, and the amount of Ti particles on the Cu metal foil surface may be deposited, for example, about 1 mg / cm ² while controlling the working time. Further, it may be a composite of a Ti thin plate and a Cu plate. Alternatively, the Ti powder may be directly placed on or applied to the end face of the ceramic insulating container. In any case, it can be implemented with equal reliability.

As a brazing material containing no active metal,
A 0.1 mm 72% Ag-Cu alloy plate was prepared. A Cu plate having a thickness of 1 mm was prepared as the intermediate layer and the diffusion preventing material. This was carried out by appropriately omitting it according to manufacturing conditions or by increasing or decreasing the plate thickness.

Next, the brazing material containing the active metal prepared above, the brazing material containing no active metal, and if necessary, each member such as the intermediate layer and the diffusion preventive material are connected between the objects to be joined (the end face of the ceramic insulating container and the sealing metal fitting). ) So that airtight bonding can be performed, and subjected to the airtight bonding process between the metal fitting and the ceramic insulating container in a vacuum atmosphere of 5 × 10 ⁻⁴ Pa. In this case, the hermetically sealing step comprises 1 heating step, 2 heating holding step, and 3 cooling step. First, the heating temperature and the holding time for joining are kept constant at 850 ° C x 5 minutes (2 heating and holding step), and further cooling after the heating and holding step is finished at 850 ° C (T
m; maximum heating temperature) to 400 ° C, the cooling rate is kept constant at 2 ° C / min (3 cooling steps), and the temperature of the object to be joined is increased from room temperature to the heating and holding temperature of 850 ° C. A vacuum valve was manufactured in which the heating rate was controlled from 0.5 ° C./min to 120 ° C./min in the temperature process (1 heating step) from 600 ° C. to 850 ° C. (Examples 1 to 5 and Comparative Example 1).
~ 2). Next, the evaluation results based on the evaluation conditions (Table 1) are shown in Table 2 (Examples 1 to 5 and Comparative Examples 1 and 2) and will be specifically described.

[0025]

[Table 1]

[0026]

[Table 2]

When the circuit of 24 kV, 50 Hz is interrupted while increasing the current by 1 kA, the interruption performance judged by the current value when the interruption is successful within 1 ms without re-ignition is When the heating rate in the process is 0.5 ° C./min (Comparative Example 1) and 1 to 20 ° C./min (Examples 1 to 3),
It showed a good interruption characteristic equivalent to that of the comparative example. However, the heating rate was 0.5 ° C./min (Comparative Example 1), which had no problem in terms of breaking performance, and an increase in contact resistance and a decrease in welding resistance, which are thought to be caused by compositional variations on the contact surface, were observed. There wasn't.

Similarly, the re-ignition characteristic judged by the frequency of re-ignition when the circuit of 24 kV × 500 A is interrupted 2000 times is also the same.
When the heating rate in the heating step is in the range of 0.5 ° C./min (Comparative Example 1) and 1 to 20 ° C./min (Examples 1 to 3), good characteristics equivalent to those of Example 1 as a comparison target are exhibited. It was When the heating rate was 0.5 min / min (Comparative Example 1), it was within the allowable range, but the airtightness tended to decrease with the lapse of the number of interruptions. When the heating rate in the heating step is 120 ° C./min (Comparative Example 2), the variation range is large as shown in Table 2, and the airtightness tends to be remarkably lowered.

As described above, when the heating rate in the heating step is in the range of 1 to 20 ° C./minute, it is shown that both the breaking performance and the re-ignition characteristic are in the preferable range. As a reference evaluation, the airtightness was evaluated using a He leak detector for all of the vacuum valves that had undergone the airtight sealing process in advance. As a guide, the leak amount is 5 x 10
^{A value of -10} (Torr · L / sec) or less was regarded as a pass. There was a failure only in some of the valves of Comparative Example 2 in which the heating rate in the heating step was 120 ° C./minute, but the valves of other Examples 1 to 5 and Comparative Example 1 were in the acceptable range. .

Further, by using the vacuum valve after the evaluation of the airtightness, 0 to 120 KV is applied to both ends of the ceramic insulating container.
Impulse voltage was applied 10 times, and the withstand voltage characteristics for evaluating the voltage value and the number of times of dielectric breakdown when dielectric breakdown was evaluated were evaluated. As a guide, the case where the dielectric breakdown voltage value was 95KV and the number of dielectric breakdowns was zero was passed. The heating rate in the heating process is 12
Only some of the valves of Comparative Example 2 at 0 ° C./min had rejected valves, but the valves of other Examples 1 to 5 and Comparative Example 1 were in the acceptable range. From such a reference evaluation,
The importance of the heating rate in the heating process is suggested for the reliability of the vacuum valve.

The above-mentioned Examples 1 to 3 and Comparative Examples 1 to 1
In Section 2, the temperature range in which the heating rate should be controlled in the heating process was shown from 600 ° C to the heating and holding temperature of 850 ° C, but in practice, the range of 750 ° C to 850 ° C was controlled to the prescribed heating rate. However, the same stable blocking characteristics as above,
The characteristics of re-ignition are shown (Examples 4 and 5).

(Examples 6 to 7 and Comparative Examples 3 to 4) In Examples 1 to 5 and Comparative Examples 1 and 2 described above, particularly 1 in the airtight sealing process is used.
The importance of the heating rate up to the holding temperature in the heating process was shown. However, even if the heating rate is set within a predetermined preferable rate range, if the subsequent two heating and holding steps (holding temperature, holding time) are not appropriate, Comparative Example 3
As shown in ~ 4, the reliability of the breaking characteristic and the restriking characteristic is not sufficient. For example, at the holding temperature, when a 72Ag-Cu brazing material containing 0.1 to 5% Ti is used as a brazing material containing an active metal and a 72Ag-Cu brazing material containing no active metal is used, the brazing material Although the attachment work temperature varies depending on the Ti content, at least about 700 ° C is required, and 900
It is desirable to set the temperature within about ℃. Further, 60Cu-Mn containing 0.5 to 5% Ti is used as a brazing material containing an active metal, and 72Ag-Cu is used as a brazing material containing no active metal.
When a brazing material is used, the brazing temperature of the brazing material also varies depending on the amount of Ti, but it is higher than that described above and requires at least about 900 ° C, preferably up to about 1000 ° C. In this embodiment, the holding temperature is 850
When the temperature was selected and the effect of the heating and holding time was investigated, when the holding time was 1 minute (Comparative Example 3), the flow of the melted active brazing material was not uniform in appearance and local solidification was present. Also,
Even when the joint interface is observed with a metallurgical microscope, a micro portion where the brazing material is not well wetted is seen on the ceramic surface, which is not preferable from the viewpoint of airtightness. Example 1 to be compared
It was also found that there were many abnormalities in the restriking characteristics compared to.

On the other hand, when the holding time is 3 minutes and 60 minutes (Examples 6 and 7), the flow of the active brazing material on the surface of the ceramic is uniform and good according to the observation with a metallurgical microscope at the joint interface. The joined state was shown. The breaking characteristics and the re-ignition characteristics equal to or higher than those of the comparative example 1 were shown.

When the holding time was 120 minutes (Comparative Example 4), the flow of the active brazing material was uniform with respect to the surface of the ceramic and a good bonding state was shown, while the C in the brazing material component was
Due to the selective evaporation of u and especially Ag, the surface of the joint after brazing had an uneven surface appearance. Both the breaking characteristic and the restriking characteristic were lower than those of the comparative example 1.
From the above, the heating rate condition in the heating step is 1 to
When the condition of 20 ° C./minute is selected, the holding time in the heating and holding step requires at least 3 minutes.

(Examples 8 to 9 and Comparative Examples 5 to 6) In the above Examples 1 to 7 and Comparative Examples 1 to 4, the cooling rate in the predetermined cooling section in the 3 cooling steps was kept constant at 2 ° C / min. However, the cooling rate is not limited to 2 ° C / min.
Table 2 within the range of min (Example 8) to 30 ° C / min (Example 9).
It has been confirmed that stable cutoff characteristics and re-ignition characteristics are exhibited.

However, when the cooling rate was 0.1 ° C./min (Comparative Example 5), the surface of the joint after brazing had an apparently uneven surface state and the brazing material composition fluctuated remarkably. A part of the material component adheres to the arc shield part, which affects the breaking characteristics and the restriking characteristics. In particular, the re-ignition probability showed a wide variation range from a good 0% to a 2.6% valve, which is at an unfavorable level.

The cooling rate was 120 ° C./min (Comparative Example 6).
According to the observation of the cross-sectional structure near the interface of the joint after brazing, the flow of the active brazing material was uniform and showed good wetting with respect to the ceramic surface, but there were many microcracks. Was recognized. This caused some valves to fail the shutoff test. Further, as a reference evaluation, He performed on the vacuum valve after the air-sealing process.
Even in the airtightness evaluation using the leak detector,
Large amount of leak in some valves is not desirable 8 × 10-7
0 (Torr · L / sec) and a remarkable leak amount. These (Comparative Examples 5 and 6) had lower cut-off characteristics and restriking characteristics as compared with the comparative examples (Table 2).

From the above, the heating rate condition in the heating step is selected to be 1 to 20 ° C./minute, and the cooling rate in the predetermined cooling section in the cooling step is 0.5 ° C./minute to 30 ° C./minute.
It was found that stable breaking and re-ignition characteristics were exhibited within the range of minutes.

(Examples 10 to 12 and Comparative Examples 7 to 8) In Examples 1 to 9 and Comparative Examples 1 to 6 described above, in the end adjusting step of the ceramic insulating container (end face of the outer tube), all of them are averaged. The case where the surface roughness (Rave.) Is fixed to 1.5 μm in advance is shown. However, in the present embodiment, the average surface roughness is not limited to 1.5 μm, and stable breaking characteristics and re-pointing are possible in the range of 0.05 to 10 μm. Exhibits arc characteristics (Table 2). However, when the average surface roughness of the end surface of the ceramic insulating container was 0.05 μm or less (Comparative Example 7), both the breaking characteristics and the re-ignition characteristics were within the preferable characteristic ranges as shown in Table 2, but a special finishing work technique was used. It is excluded from the viewpoint of mass productivity and cost. Further, when the average surface roughness is 100 μm (Comparative Example 8), the flow of the brazing material becomes non-uniform, a large amount of the brazing material is required, and a space is generated between the brazing material and the metal fitting. Is not preferable, and is also not preferable from the viewpoint of airtightness. A vacuum leak was found on some vacuum valves, making them untestable in terms of barrier performance. Also in the re-ignition characteristic, the variation range was remarkably 0.4 to 5.8% (Comparative Examples 7 and 8). On the other hand, the average surface roughness (Rave.) Is 0.05-
In 10 μm (Examples 10 to 12), Example 1 to be compared
Comparing with, the breaking characteristics and restriking characteristics were good.

(Examples 13 to 14 and Comparative Example 9) The above Example 1
In each of Comparative Examples 1 to 8 and Comparative Examples 1 to 8, a ceramic insulating container was subjected to a preheat treatment step at a temperature of 1650 ° C. before being subjected to the airtight sealing step. In this example, the temperature in the pre-heat treatment step showed a sufficient effect on the stability of the breaking property and the restriking property by the treatment at 600 ° C or higher (Examples 13 to 14). On the other hand, when the temperature of the pre-heat treatment step was 400 ° C., there was no effect, and there were remarkable variations in the breaking characteristics and restriking characteristics (Comparative Example 9).

(Examples 15 to 19, Comparative Example 10) The above Example 1
14 to Comparative Examples 1 to 9, the brazing filler metal containing the active metal used in the vacuum valve assembly (airtight sealing step) was 72%.
% Ag-Cu-0.5% Ti is shown as a representative brazing material, but the brazing material containing an active metal that can be used is not limited to this, and at least one of Ti, Zr, Hf, V and Cr is used. Ag or Ag containing 0.1 to 5% by weight in total
-A brazing material containing Cu as a main component, for example, 72% Ag-Cu-
0.1% Ti brazing material, 72% Ag-Cu-5% Ti brazing material, 7
2% Ag-Cu- 0.5% Zr brazing material, 72% Ag-Cu-
Even with the 0.1% Hf brazing material and the 72% Ag-Cu-0.1% Cr brazing material, the breaking characteristics and the re-ignition characteristics were almost the same as those of the comparative example 1 (Examples). 15-19). However, with the 72% Ag-Cu brazing material containing no active metals shown as a reference, the wettability to the surface of the ceramic insulating container was not obtained, resulting in poor bonding.
A remarkable vacuum leak is also recognized, which is not preferable. Both the breaking characteristic and the restriking characteristic showed remarkable variations (Comparative Example 1
0).

The evaluation results of Table 2 show the comprehensive evaluation results as a vacuum valve in consideration of the airtightness and the bondability evaluated together with the breaking characteristic and the restriking characteristic. On the other hand, in Examples 1 to 19 and Comparative Examples 1 to 10, Ag-Cu was used as an example of the brazing material containing no active metal. However, the brazing material is not limited to Ag-Cu-In and Ag-Cu-Sn. , C
Even the brazing material made of u-Mn achieves the purpose. Further, as the form of the brazing material containing the active metal, the one using the plate-shaped brazing material is shown, but the supply of the active metal is not limited to the plate shape, but may be powder, film or foil. Also achieve the purpose. Further, as the sealing metal fittings in the above-mentioned Examples and Comparative Examples, the iron-based alloy or the iron-based low thermal expansion coefficient alloy such as SUS304, 42 alloy or Kovar coated with Cu or Ni was shown. (Ni70Wt%
The same characteristics were obtained even with a sealing metal fitting made of Cu100 Wt%.

Further, the same effect can be obtained by simultaneously using the manufacturing method of the present invention at the locations where the brazing material is required, such as the outer tube of the insulating container and the sealing metal fitting, the current-carrying shaft and the electrode, the arc shield and the mounting member. At the same time, only one joining operation is required, and cost reduction can be realized. At this time, if only the current-carrying shaft and the electrodes are previously bonded, the reliability of the bonding is significantly improved.

[0044]

As described above, according to the present invention, between the end portion of the insulating container in which the pair of electrodes are arranged so that they can be contacted and separated from each other, and the sealing metal member for sealing the insulating container with the lid. In a method for manufacturing a vacuum valve, in which a brazing material is placed on the insulating container and the insulating container and the sealing metal fitting are hermetically sealed while exhausting the whole in a vacuum,
The heating process of heating from 00 ℃ to the brazing work temperature at a temperature rising rate of 1 to 20 ℃ / min and the brazing work temperature to 400 ℃
Since the cooling step of cooling at a cooling rate of 0.5 to 30 ° C./min is provided, it is possible to improve the bondability and reduce deterioration of the breaking characteristics and the re-ignition characteristics over a long period of time.

Front Page Continuation (72) Inventor Mikio Okawa 1 Toshiba Town, Fuchu City, Tokyo Inside the Fuchu Factory, Toshiba Corporation (72) Inventor Miho Maruyama 1 Komukai Toshiba Town, Kawasaki City, Kanagawa Prefecture Toshiba Research & Development Co., Ltd. Inside the Center (72) Inventor Takashi Kusano 1st Toshiba Town, Fuchu City, Tokyo Inside the Fuchu Factory, Toshiba Corporation

Claims (9)

[Claims] 1. A brazing material is inserted and placed between an end of an insulating container in which a pair of electrodes are arranged so as to be able to come into contact with and separate from each other and a sealing metal member for sealing the insulating container with a lid. In a method for manufacturing a vacuum valve in which the insulating container and the sealing metal fitting are hermetically sealed while exhausting the whole in a vacuum, heating is performed at a temperature rising rate of 1 to 20 ° C / min from 600 ° C to the brazing working temperature. Heating step to
A method for manufacturing a vacuum valve, comprising: a brazing process temperature to 400 ° C; and a cooling step of cooling at a cooling rate of 0.5 to 30 ° C / min. 2. A pair of electrodes joined to a current-carrying shaft are arranged inside so as to be able to come into contact with and separate from each other, and an end portion of an insulating container provided with an arc shield around the electrodes and the insulating container are sealed with a lid. In a method for manufacturing a vacuum valve, in which a brazing material is placed between the sealing metal fitting and the sealing metal fitting, and the insulating container and the sealing metal fitting are hermetically sealed while exhausting the whole in a vacuum, 600 ° C. A heating step for heating up to the working temperature at a temperature rising rate of 1 to 20 ° C./min; and a cooling step for cooling the brazing working temperature to 400 ° C. at a cooling rate of 0.5 to 30 ° C./min. The current-carrying shaft and the electrode, the arc shield and its mounting member are also placed with a brazing material interposed therebetween to exhaust the whole in a vacuum, and the airtight seal between the insulating container and the sealing metal fitting, Make sure that the current-carrying shaft and electrode, and the arc shield and its mounting member are joined together. A method for manufacturing a vacuum valve, characterized in that 3. The method for manufacturing a vacuum valve according to claim 2, wherein the current-carrying shaft and the electrode are bonded in advance in an inert atmosphere containing a vacuum atmosphere. 4. The method of manufacturing a vacuum valve according to claim 1, wherein in the heating step, the temperature is kept at least 700 ° C. for at least 3 minutes to maintain the heating. . 5. The heating step is at least 750 to 850.
The method is characterized in that heating is performed up to ℃ at a temperature rising rate of 1 to 20 ℃ / min, and in the cooling step, at least 900 to 400 ℃ is cooled at a cooling speed of 0.5 to 30 ℃ / min. The method for manufacturing a vacuum valve according to any one of claims 1 to 4. 6. The average surface roughness of the end portion of the insulating container is 0.
The vacuum valve manufacturing method according to any one of claims 1 to 5, wherein the vacuum valve is made to have a thickness of 05 to 10 µm. 7. The heat treatment step of heating the insulating container to 600 to 1700 ° C.
~ The method for manufacturing a vacuum valve according to claim 6. 8. The brazing material is mainly composed of Ag or Ag.Cu containing 0.1 to 5 wt% of at least one of Ti, Zr, Hf, V and Cr. The method for manufacturing a vacuum valve according to any one of claims 1 to 7. 9. Ag-Cu, Ag-Cu-In, Ag-
9. The method of manufacturing a vacuum valve according to claim 8, further comprising at least one brazing material selected from Cu-Sn and Cu-Mn.