Joining body structure of vacuum valve, and vacuum valve

Abstract

To prevent the occurrence of a defect in a brazing material layer in a joining body structure of a vacuum valve.SOLUTION: A joining body structure of a vacuum valve according to an embodiment has: a first base material having a first joining surface; a second base material having a second joining surface facing the first joining surface; a mesh sheet provided between the first joining surface and the second joining surface; and a brazing material layer held together with the mesh sheet between the first joining surface and the second joining surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a vacuum interrupter assembly structure and a vacuum interrupter. [Background technology]

[0002] A brazing process is used to join metals together in the manufacture of vacuum vessels. This process can sometimes result in defects such as dripping of the molten brazing material and voids. For example, in the sealing area, a ceramic porcelain insulator is metallized and brazed to a metal sealing fitting. If brazing material drips from the metallized area onto the ceramic porcelain insulator during joining, it can become a starting point for discharge in the vacuum vessel, making it more susceptible to dielectric breakdown. Furthermore, if voids form in the brazing material layer, the valve will not be sealed properly and can become a source of leaks in the vacuum valve, reducing the vacuum level inside the valve and causing dielectric breakdown. In addition, there is a technique for forming a porous layer on one side of the metal to prevent dripping, but forming the porous layer requires an additional process, and it is difficult to adjust the sintering conditions to stabilize the quality. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-182967 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of an embodiment of the present invention is to suppress the occurrence of defects in the brazing material layer in the joined body structure of a vacuum interrupter. [Means for solving the problem]

[0005] According to an embodiment, a first base material having a first joining surface; a second base material having a second bonding surface opposite to the first bonding surface; a mesh sheet provided between the first bonding surface and the second bonding surface; and A vacuum valve joint structure is provided that includes a brazing material layer held together with the mesh sheet between the first joint surface and the second joint surface. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a cross-sectional view showing the configuration of a joined body structure of a vacuum interrupter according to a first embodiment. [Figure 2] FIG. 2 is a front view illustrating an example of the configuration of a mesh sheet. [Figure 3] FIG. 6 is a vertical cross-sectional view showing the configuration of a vacuum interrupter according to a second embodiment. [Figure 4] 3A and 3B are diagrams illustrating an example of a joined body structure of the vacuum interrupter according to the first embodiment during joining. [Figure 5] FIG. 1 is a diagram showing the configuration of a test piece used in Example 1. [Figure 6A] 1 is a schematic diagram showing the experimental results of Example 1. FIG. [Figure 6B] 1 is a schematic diagram showing the experimental results of Example 1. FIG. [Figure 6C] 1 is a schematic diagram showing the experimental results of Example 1. FIG. [Figure 7] FIG. 10 is a diagram illustrating the configuration of a test piece used in Example 2. [Figure 8] FIG. 10 is a diagram schematically showing an ultrasonic microscope image of Example 2. [Figure 9] 1 is an electron microscope photograph of a cross section of the bonded structure of Example 2. [Figure 10] FIG. 10 is a diagram for explaining the arrangement of the mesh sheet in the third embodiment. [Figure 11] FIG. 10 is a cross-sectional view showing an example of a bonded structure of Example 3. [Figure 12] FIG. 10 is a diagram illustrating an example of a bonded structure according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] The vacuum interrupter assembly structure according to the first embodiment includes a first base material having a first bonding surface, a second base material having a second bonding surface opposite the first bonding surface, and a mesh sheet and a brazing material layer held by the mesh sheet between the first and second bonding surfaces.

[0008] In addition, the vacuum valve of the second embodiment comprises an insulating container having open ends at both ends, a vacuum container having a pair of sealing fittings joined to the open ends, and a pair of electrodes detachably attached to the vacuum container, and has the above-mentioned assembly structure in at least a portion thereof.

[0009] According to the first and second embodiments, by providing a brazing material layer together with a mesh sheet between the first and second joining surfaces of the joined body structure, the molten brazing material is held by the mesh sheet during joining and is less likely to spread to areas other than the joining surface where the mesh sheet is placed, thereby suppressing the occurrence of defects such as dripping of the brazing material and voids.

[0010] Furthermore, if defects such as dripping of the solder material or voids occur in the joint structure of the insulating container of the vacuum valve, they can become the starting point for discharge in the vacuum container, making it more likely to cause dielectric breakdown. However, by using the above-mentioned joint structure, it is possible to suppress the occurrence of such dielectric breakdown.

[0011] Hereinafter, embodiments will be described with reference to the drawings. The disclosure is merely an example, and appropriate modifications that are easily conceivable by those skilled in the art while maintaining the gist of the invention are naturally included within the scope of the present invention. Furthermore, in order to clarify the explanation, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. Furthermore, in this specification and each drawing, elements similar to those described above with reference to the previous drawings may be designated by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0012] FIG. 1 is a cross-sectional view showing the configuration of the joined body structure of the vacuum interrupter according to the first embodiment. FIG. 2 shows a front view illustrating an example of the configuration of the mesh sheet. As shown in the figure, the vacuum interrupter assembly structure 110 includes a first base material 102a having a first joining surface 102c and a second base material 102b having a second joining surface 102d opposite the first joining surface 102c. Between the first joining surface 102c and the second joining surface 102d, for example, a mesh sheet 101 and a brazing filler metal layer 103 are provided. The brazing filler metal layer 103 is formed by cooling and solidifying a brazing filler metal having a melting point lower than that of the first base material 102a and the second base material 102b. The brazing filler metal melted during joining can penetrate between the first joining surface 102c and the second joining surface 102d by capillary action. When the mesh sheet 101 is provided, the brazing filler metal, in its molten state, is held between the mesh sheet and the first joining surface 102c or between the mesh sheet and the second joining surface 102d by capillary action. This improves the wettability of the brazing filler metal due to capillary action, and prevents the occurrence of defects such as dripping and voids caused by the molten brazing filler metal. After joining, the molten brazing filler metal is cooled and solidified to form a brazing filler metal layer 103 held by the mesh sheet 101.

[0013] As shown in FIGS. 1 and 2, the mesh sheet 101 may have, for example, a plain weave structure, with wires 101a woven horizontally and wires 101b woven vertically. The diameter of the wires 101a and 101b is represented by the wire diameter dw. The mesh size is represented by the distance dm between the central axes of adjacent wires 101a. The mesh sheet 101 may have a structure in which metal wires are woven, such as a plain weave, twill weave, plain tatami weave, or twill tatami weave, or a perforated metal plate. The in-plane pore area Sp corresponds to the area of ​​the pores surrounded by the wires 101a and 101b. The equivalent in-plane pore diameter dp corresponds to the distance between adjacent wires 101a. The metal plate may have a surface roughness sufficient to allow the molten brazing filler metal to penetrate between the first joining surface 102c and the second joining surface 102d by capillary action. As the wire diameter dw and the mesh opening dm of the mesh sheet 101 increase, the pore size required for the capillary force to be exerted increases, and the capillary force tends to decrease. Since it is necessary to maintain a state in which the capillary force is higher than gravity, both the wire diameter dw and the mesh opening dm can be set to the order of millimeters or less.

[0014] Table 1 below shows the wire diameter dw (mm), mesh size dm (mm), and in-plane pore area Sp (mm) assuming the use of a mesh sheet made of copper (Cu) and a brazing filler metal made of 28% by weight Ag and 72% by weight Cu. 2 ), equivalent in-plane pore diameter dp (mm), gravity (N) acting on the brazing filler metal in the pore, and capillary force (N) are shown. The in-plane pore area in Table 1 was calculated by approximating the area enclosed by wire 101a, wire 101b, and the joining surface in Figure 1 as a triangle. The gravity acting on the brazing filler metal in the pore was calculated by approximately calculating the volume of the pore as the product of the in-plane pore area Sp and the wire diameter dw, and then calculating the volume of the pore from the weight of the brazing filler metal. The capillary force was calculated by approximating the surface tension component acting on the side of the pore as π·dp·σ·cosθ, assuming the surface tension σ of the brazing filler metal filling the pore to be 900 mN / m and the contact angle θ with the pore to be 0°.

[0015] [Table 1]

[0016] From Table 1, it can be seen that when the wire diameter is 10 mm, the gravity force of 4.41E-2 (N) acting on the brazing material in the pores becomes greater than the capillary force of 2.26E-2 (N), and therefore when the wire diameter is 10 mm or more, the capillary force tends to cease to be expressed. Furthermore, since the brazing filler metal generally used for brazing is in the form of a foil of about 0.1 mm, it is desirable that one or two pieces of this foil be enough to fill the pores. Since the diameter of the pores is roughly the same order as the wire diameter, the wire diameter can be 0.1 to 0.2 mm or less.

[0017] Examples of materials for the brazing material include Cu-silver (Ag) alloy, bismuth (Bi)-Cu alloy, and Cu-zinc (Zn) alloy. Materials that can be used for the mesh sheet include, for example, Cu, Cu-containing alloys such as Cu-Ni, Cu-Fe, Cu-Mn, Cu-P, Cu-Pd, Cu-Ti, Cu-Zr, Cu-Ag, Cu-Au, and Cu-Cd, nickel (Ni), and Ni-containing alloys such as Ni-Fe, Ni-Au, Ni-Mo, Ni-Co, Ni-Cr, and Ni-Mn. Furthermore, by selecting a combination that allows the brazing material and mesh sheet to react with each other, it is possible to control the material properties of the brazing material layer, such as increasing the melting point and resistance.

[0018] The first base material, the second base material, the brazing material layer, and the mesh sheet may each contain a first metal component made of Cu or a Cu alloy. If Cu or a Cu alloy is used as the first metal component in the materials for the brazing filler metal and mesh sheet, the Cu component in the mesh sheet will further dissolve into the brazing filler metal layer, increasing the Cu content and further increasing the melting point of the brazing filler metal layer. For example, if Cu is used for the first base material, a Cu alloy for the second base material, Cu for the mesh sheet, and 72 wt% Ag-28 wt% Cu (melting point 780°C, conductivity 87% IACS) for the brazing material, and the materials are joined at 900°C, the brazing material layer will have a high melting point, and the melting point can be raised to above 900°C.

[0019] In addition, the first base material, the second base material, and the brazing material layer each contain a first metal component consisting of Cu or an alloy containing Cu, and the mesh sheet can contain a second metal component consisting of Ni or an alloy containing Ni. Furthermore, if Cu or a Cu alloy is used as the brazing material and Ni or a Ni alloy is used as the mesh sheet material, the Ni component of the mesh sheet will dissolve into the brazing material layer, forming a Ni-Cu solid solution and resulting in a high resistance layer. For example, if Cu is used for the first base material, a Cu alloy for the second base material, Ni for the mesh sheet, and 72 wt% Ag-28 wt% Cu for the brazing filler metal, and they are joined at 900°C, the brazing filler metal layer will have high resistance, and the conductivity can be reduced to 75% IACS or less. As described above, according to the embodiment, high-quality joining can be achieved in brazing a vacuum interrupter.

[0020] FIG. 3 is a vertical cross-sectional view showing the configuration of a vacuum interrupter according to the second embodiment. As shown in the figure, the vacuum valve 100 has openings on both ends and comprises a cylindrical ceramic container 1 made of, for example, alumina porcelain as an insulating container, a fixed sealing metal fitting 2 sealed to one opening, and a movable sealing metal fitting 3 sealed to the other opening. A vacuum is maintained inside the vacuum valve 100. A central opening is provided in the fixed sealing metal fitting 2, through which a fixed current-carrying shaft 4, which serves as one of the electric paths, is fixed. A fixed electrode 5 is fixed to the end of the fixed current-carrying shaft 4 within the ceramic container 1. A movable electrode 8 is fixed to the end of a movable current-carrying shaft 9, which serves as the other electric path and movably passes through the central opening provided in the movable sealing metal fitting 3. A fixed contactor 6 is fixed to the end face of the fixed electrode 5, thereby forming a bonded structure between the fixed electrode 5 and the fixed contactor 6. A movable contactor 7, which faces the fixed contactor 6 and serves as a pair of separable contacts, is fixed to the end face of the movable electrode 8, thereby forming a bonded structure between the fixed contactor 6 and the movable contactor 7. Furthermore, a bonded structure with the fixed sealing metal fitting 2 is formed at one open end of the ceramic container 1, and a bonded structure with the movable sealing metal fitting 3 is formed at the other open end of the ceramic container 1.

[0021] The portion of the movable current-carrying shaft 9 on the movable sealing metal fitting 3 side from its central portion extends outside the ceramic container 1, and a bellows cover 10 is provided at this portion for hermetic sealing, with one end of a freely expandable cylindrical bellows 11 attached to the bellows cover 10. The other end of the bellows 11 is sealed to the central opening of the movable sealing metal fitting 3. This allows the movable current-carrying shaft 9 to move axially while maintaining the vacuum inside the insulating container 1. A cylindrical arc shield 12 is provided around the fixed electrode 5, movable electrode 8, fixed contactor 6, and movable contactor 7 to prevent metal vapor and molten metal, generated during opening and closing, from adhering to the inner wall of the insulating container 1 and reducing its insulation resistance.

[0022] In the vacuum valve 100, the vacuum valve joint structure according to the first embodiment can be applied to at least one of the joint structure between one opening end of the ceramic container 1 and the fixed side sealing metal fitting 2, the joint structure between the other opening end of the ceramic container 1 and the movable side sealing metal fitting 3, the joint structure between the fixed side electrode 5 and the fixed side contactor 6, or the joint structure between the fixed side contactor 6 and the movable side contactor 7, but is not limited to this.

[0023] FIG. 4 is a diagram illustrating an example of the joined structure used in FIG. 3 during joining. As shown in the figure, one opening 1a serving as a first joining surface of a ceramic container 1 serving as a first base material can be chamfered. A metallized layer 206 is provided on the opening 1a to improve adhesion when brazing to a fixed sealing metal fitting 2. The metallized layer 206 includes a molybdenum (Mo)-manganese (Mn) layer 205 provided on the opening 1a and a Ni plating 204 provided on the Mo-Mn layer 205. A mesh sheet 201 and a brazing material layer 207 held by the mesh sheet 201 are provided on the metallized layer 206. Here, even if the brazing material melts, it is held by the mesh sheet 201, so defects such as dripping of the brazing material or voids do not occur.

[0024] Hereinafter, the embodiment will be described more specifically with reference to examples. Example 1 A first embodiment will be described with reference to FIGS. 5, 6A, 6B, and 6C. In Example 1, an example will be described in which a mesh sheet is used to control the area where the brazing material spreads. FIG. 5 shows a diagram illustrating the configuration of the test piece used in Example 1. Test specimen 300 was prepared by placing a 0.144mm plain weave mesh sheet 301 made by weaving 0.1mm diameter oxygen-free copper wires on a 20mm x 20mm x 5mm oxygen-free copper flat plate 303. The mesh sheet structure was not limited to any particular weave method or dimensions, as long as it exhibited capillary action. However, the mesh sheet thickness could be 0.2mm or less, considering the thickness of the joints. For test specimen 300, square mesh sheets measuring 5mm x 5mm were cut from the four corners of a 20mm x 20mm square mesh sheet 301, forming cross-shaped mesh sheets 301. A 9mm diameter spherical brazing filler metal 302 made of 28wt% Ag / 72wt% Cu eutectic silver brazing filler metal was placed near the center of mesh sheet 301.

[0025] This is a vacuum of 10 -3 The specimen was heated to 800°C in a Pa atmosphere, which is a temperature above the melting point of the eutectic silver solder, and the state was checked after holding the specimen for 20 minutes. Schematic diagrams showing the experimental results are shown in FIGS. 6A, 6B, and 6C. FIG. 6A shows the state of the mesh sheet and brazing material before heating, FIG. 6B shows the state of the mesh sheet and brazing material after holding for 2 minutes, and FIG. 6C shows the state of the mesh sheet 301 and brazing material 302 after holding for 4 minutes. As shown in the figure, it was confirmed that the brazing material 302 after wetting and spreading was spread only within the area where the mesh sheet 301 was installed, and did not spread to the four corner areas where the mesh sheet 301 was not installed.

[0026] Example 2 A second embodiment will be described with reference to FIGS. 7, 8, and 9. FIG. In Example 2, an example of a joint structure is described in which a brazing filler metal with lower wettability than the 28 wt % Ag 72 wt % Cu eutectic silver brazing filler metal of Example 1 is used in combination with a mesh sheet to ensure appropriate wettability and reduce defects such as voids on the joint surface.

[0027] FIG. 7 shows a diagram for explaining the configuration of the test piece used in Example 2. As shown in the figure, a mesh sheet 401 with a plain weave structure of 0.144 mm mesh size, made by weaving oxygen-free copper wires with a wire diameter of 0.11 mm, was placed on an oxygen-free copper flat plate 403 measuring 20 mm length x 20 mm width x 5 mm thickness, followed by a 60 wt % Ag 40 wt % Cu silver brazing sheet 402 measuring 20 mm length x 20 mm width x 0.2 mm thickness, and an oxygen-free copper flat plate 404 measuring 20 mm length x 20 mm width x 5 mm thickness, to obtain a test piece 400. The structure of mesh sheet 401 is not limited to any particular dimensions as long as it has a plain weave structure that exhibits capillary action, but the thickness can be 0.2 mm or less in consideration of the thickness of the joint. This is a vacuum of 10 -3 The temperature was raised to 900°C in a Pa atmosphere and held for 20 minutes to bond the materials together, obtaining a bonded structure. After bonding, the defect rate of the bonding interface between the oxygen-free copper plate and the silver brazing layer obtained by bonding was evaluated using an ultrasonic microscope. In the observation with the ultrasonic microscope, the test piece 400 was placed so that ultrasonic waves from the probe were incident perpendicularly on the bonding surface, and the probe was scanned within the bonding surface while measuring the reflectivity of the ultrasonic waves at the bonding interface, and the bonding interface was imaged.

[0028] FIG. 8 is a diagram showing a schematic representation of an ultrasonic microscope image of Example 2. In the ultrasonic microscope image 502, the reflectivity is high where defects exist, so the areas with high reflectivity were assumed to be void defects, and the ratio of the void defects 503 to the bonding interface 504 was calculated as an area ratio, which was 16%. Furthermore, the cross section of the bonded body was observed with a scanning electron microscope to confirm the presence of void-like defects on the bonded surface.

[0029] FIG. 9 shows an electron microscope photograph of a cross section of the bonded structure of Example 2. As shown in the figure, in the electron microscope photograph 501 of the cross section of the bonded structure of Example 2, it can be seen that the mesh sheet 401 provided between the flat plates 403 and 404 is melted into the brazing material layer 402-1, and no significant defects were confirmed. As Comparative Example 1, a comparative test piece was prepared in the same manner as Test Piece 400 except that it did not include a mesh sheet. As in Example 2, the test piece was observed with an ultrasonic microscope and images of the bonded surface were taken. Furthermore, the cross section of the bonded body was observed with a scanning electron microscope to confirm the presence of void-like defects at the bonded surface. As a result, in Comparative Example 1, several void-like defects were observed in the cross section of the bonded body, and the defect rate based on the ultrasonic microscope image was about 40%. In contrast to this, in Example 2, there were no large void-like defects in the cross section of the bonded body, and the defect rate in the ultrasonic microscope image was low at 16%, which indicated that a good bonded interface could be obtained.

[0030] Example 3 A third embodiment will be described with reference to FIGS. In Example 3, instead of the joined structure of the ceramic container 1 of the vacuum interrupter 100 in Figure 3 and the fixed sealing metal fitting 2 sealed to one of the openings, an joined structure using a mesh sheet as shown in Figure 11 is applied, thereby preventing dripping of the brazing material. FIG. 10 shows a diagram for explaining the arrangement of the mesh sheets before bonding. FIG. 11 is a cross-sectional view showing an example of the bonded structure of Example 3. As shown in FIG.

[0031] As shown in the figure, in the vacuum interrupter assembly structure 600 of Example 3, a ceramic porcelain insulator tube 602a serving as a first base material is joined to a fixed-side sealing metal fitting 602b serving as a second base material. One opening 602-1 serving as a first joining surface of the ceramic porcelain insulator tube 602a can be C-face processed. A metallized layer 602c is provided on the opening 602-1 to improve adhesion when brazing to the fixed-side sealing metal fitting 602b. The metallized layer 602c has a Mo-Mn layer provided on the opening 602-1 and Ni plating provided on the Mo-Mn layer. The metallized layer 602c is also provided up to the center of the C-face of the opening 602-1. A mesh sheet 601 having the same surface shape as the joining surface of the fixed-side sealing metal fitting 602b is placed on the metallized layer 602c. The mesh sheet 601 has a plain weave structure of oxygen-free copper wires with a wire diameter of 0.11 mm and mesh openings of 0.144 mm.

[0032] Next, a eutectic silver solder (28 wt % Ag, 72 wt % Cu) sheet having the same surface shape as the joining surface of the fixed sealing metal fitting 602b was placed between the joining surface of the fixed sealing metal fitting 602b and the mesh sheet 601 in FIG. -3 The temperature was raised to 800° C. in a Pa atmosphere and maintained at that temperature for 1 hour to obtain the bonded structure shown in Fig. 11. In the figure, 105 denotes the end face of the ceramic bushing 602a. After inspecting the appearance after brazing, it was found that the brazing material had not reached the C-face and was properly held on the end face of the ceramic tube.

[0033] Example 4 A fourth embodiment will be described with reference to FIG. In Example 4, an example is shown in which dripping of the brazing material is prevented by applying a joint structure using a mesh sheet as shown in Figure 12 instead of the joint structure between the fixed side electrode 5 and the fixed side contactor 6 of the vacuum interrupter 100 in Figure 3.

[0034] FIG. 12 is a diagram illustrating the configuration of an example of the bonded structure of Example 4. In FIG. In the vacuum interrupter joint structure 700 of Example 4, a fixed electrode 705 as a first base material fixed to the end of a fixed current-carrying shaft 704 is joined to a fixed contactor 706. As shown in the figure, a mesh sheet 701 having a surface shape similar to that of the first joint surface 705a is placed on a first joint surface 705a of the fixed electrode 705. The mesh sheet 701 has a plain weave structure of oxygen-free copper wire with a wire diameter of 0.11 mm and a mesh size of 0.144 mm. A eutectic silver solder (28 wt % Ag, 72 wt % Cu) sheet having a surface shape similar to that of the joint surface of the fixed contactor 706 is placed between the first joint surface 705a and the mesh sheet 701. These are placed in a vacuum chamber at a degree of vacuum of 10 -3 The temperature was raised to 800°C in a Pa atmosphere and held at that temperature for 1 hour. When the appearance after brazing was checked, it was found that the brazing material was not dripping and was properly held on the first bonding surface 705 a of the fixed electrode 705 .

[0035] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0036] 1, 602a...insulating container, 2, 3, 602b...sealing metal fitting, ...vacuum container, 5, 8...electrode, 100...vacuum valve, 101, 201, 301, 401, 601, 701...mesh sheet, 102a...first base material, 102b...second base material, 102c, 705a...first bonding surface, 102d...second bonding surface, 103, 207, 402-1...brazing material layer, 302, 402...brazing material, 110, 600, 700...bonded body structure, 602-1...opening end,

Claims

1. a first base material having a first joining surface; a second base material having a second bonding surface opposite to the first bonding surface; a mesh sheet provided between the first bonding surface and the second bonding surface; and A vacuum interrupter joint structure including a brazing material layer held together with the mesh sheet between the first joint surface and the second joint surface.

2. 2. The vacuum valve assembly structure of claim 1, wherein the brazing material used in the brazing material layer is held in a molten state between the mesh sheet and the first joining surface, and between the mesh sheet and the second joining surface, by capillary action when joining.

3. 2. The vacuum interrupter assembly structure according to claim 1, wherein the first base material, the second base material, the brazing material layer, and the mesh sheet each contain a first metal component made of copper or a copper alloy.

4. 2. The vacuum valve joint structure according to claim 1, wherein the first base material, the second base material, and the brazing material layer each contain a first metal component made of copper or an alloy containing copper, and the mesh sheet contains a second metal component made of nickel or an alloy containing nickel.

5. 4. The vacuum valve assembly structure according to claim 3, wherein the brazing material layer further contains copper components from the mesh sheet that are dissolved during joining, thereby giving the brazing material a higher melting point than the brazing material used in the brazing material layer.

6. 5. The vacuum valve assembly structure according to claim 4, wherein the brazing filler metal layer further contains nickel components from the mesh sheet that are dissolved during joining, thereby forming a solid solution of copper and nickel, and having a higher resistance than the brazing filler metal used in the brazing filler metal layer.

7. an insulating container having open ends at both ends; a vacuum vessel having a pair of sealing metal fittings joined to the open end; a vacuum valve comprising a pair of electrodes detachably provided on the vacuum vessel, a first base material having a first joining surface; a second base material having a second bonding surface opposite to the first bonding surface; a mesh sheet provided between the first bonding surface and the second bonding surface; and A vacuum valve including a joint structure including a brazing material layer held together with the mesh sheet between the first joint surface and the second joint surface.

8. 8. The vacuum valve according to claim 7, wherein the first base material is the insulating container, and the second base material is the sealing metal fitting.

9. 8. The vacuum interrupter according to claim 7, wherein the first base material is a contact point of the electrode, and the second base material is a current-carrying shaft of the electrode.

10. 8. The vacuum valve according to claim 7, wherein the brazing material used in the brazing material layer is held in a molten state between the mesh sheet and the first joining surface and between the mesh sheet and the second joining surface by capillary action when joined.

11. 8. The vacuum valve according to claim 7, wherein the first base material, the second base material, the brazing material layer, and the mesh sheet each contain a first metal component made of copper or a copper alloy.

12. 8. The vacuum valve according to claim 7, wherein the first base material, the second base material, and the brazing material layer each contain a first metal component consisting of copper or an alloy containing copper, and the mesh sheet contains a second metal component consisting of nickel or an alloy containing nickel.

13. The vacuum valve according to claim 11, wherein the brazing material layer further contains copper components from the mesh sheet that are dissolved during joining, thereby giving the brazing material a higher melting point than the brazing material used in the brazing material layer.

14. The vacuum valve according to claim 12, wherein the brazing filler metal layer further contains nickel components from the mesh sheet that are dissolved during joining, thereby forming a solid solution of copper and nickel and having a higher resistance than the brazing filler metal used in the brazing filler metal layer.

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