JPH1061622A - Airtight joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To join members made of metals difficult to be melted or active metals to each other while securing strength and air tightness. SOLUTION: Matched mother materials 1 and 2 are superposed in a backside plate 3, and at least one of the mother materials 1 and 2 is a metal difficult to be melted having a melting point of 2000 deg.C or higher or an active metal of IV class, a plurality of holes 4 penetrating the mother materials 1 and 2 from the backside plate 3 are formed at intervals along the matched parts, and rivets 5 are provided in the holes. Melted metal solder layers made of solder materials are formed for sealing gaps between the rivets and the mother materials 1 and 2, between the mother materials 1 and 2 and between the backside plate 3 and the mother materials 1 and 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint for hermetically joining metal members, and more particularly to a joint structure most suitable for hermetically joining members made of hard-to-melt metal or active metal.

[0002]

2. Description of the Related Art Joining methods used for structures such as metal containers include fusion welding (welding) using an arc, TIG, laser, electron beam, etc., brazing welding, riveting and bolting. There is mechanical joining by mechanical joining means.

[0003] Fusion welding is generally called "welding" and heats a portion of a base material to be welded and fuses only the base material or a base material and a filler metal to produce a molten metal. It is a method of solidifying and joining, and is widely used in the manufacture of structures, mainly ferrous metals. However, since the base material needs to be melted by the fusion welding method, it is essential to heat the base material to a temperature equal to or higher than the melting point of the base material. In addition, since the base material is accompanied by melting and solidification, structural changes, that is, recrystallization and coarsening are inevitable, and changes in properties such as embrittlement near the weld joint and reduced strength due to residual stress deformation and structural changes. Occurs. Therefore, it is particularly difficult to apply to hardly fusible metals such as molybdenum and tungsten which are remarkably embrittled by coarsening of crystal grains accompanying melting and solidification.

[0004] Further, depending on the contents of the container, a clad material composed of a group IV active metal having excellent corrosion resistance, such as Ti (titanium), Ta (tantalum), or Nb (niobium), or a refractory metal is used. Used mainly in the chemical industry. In the case of such a clad material, both the material on the main body side and the material on the composite material side are melted together, and a brittle intermetallic compound is generated, so that the fusion welding method cannot be applied.

[0005] On the other hand, brazing is also called "brazing",
Do not melt the base metal <Mold the filler metal (brazing material) having a melting point lower than that of the base metal, and use the capillary phenomenon to spread over the gap between the joining surfaces to form a molten metal brazing layer This is a method for joining. As a result, crystal grains do not become coarse due to melting and solidification of the base material and embrittlement due to the formation of intermetallic compounds does not occur. There are advantages such as low stress. Furthermore, brazing is suitable for materials that require high energy for melting the base material, such as refractory metals, or for materials that are liable to crack during solidification. However, brazing has a problem that the bonding strength is lower than that of the fusion welding method.

[0006] Joining by mechanical joining means such as rivets or bolts has been applied for a long time and is stable in strength, but has a problem in airtightness of the joint, for example, gas sealability. Therefore, methods such as reducing the rivet interval from the interval required to ensure strength, or covering the joint by plasma spraying, have been taken.
There was a problem that it was difficult to secure stable airtightness.

[0007]

Therefore, for example, Mo
(Molybdenum), W (tungsten), hard-to-melt metals such as super heat-resistant alloys, Group IV active metals such as Ti and Zr (zirconium), or cladding materials using these metals as composite materials. However, as described above, in fusion welding, characteristic changes such as embrittlement and a decrease in strength near the fusion welding joint are caused, and application is difficult. Another problem is that brazing has low joining strength. On the other hand, the joint by the mechanical joining means is difficult to manufacture the flange portion without using welding, and there is no appropriate packing that can withstand the high temperature to be used, and there is a problem in the airtightness of the joint, for example, gas sealability. ,
There were no joints suitable for hard-to-melt metals and active metals that had both strength and airtightness.

The present invention has been made in view of the above circumstances, and provides an airtight joint which can join a member made of a hardly fusible metal or an active metal while ensuring strength and airtightness. It is in.

[0009]

According to the present invention, there is provided a hermetic joint in which the end of one metal member is overlapped with the end of another metal member, and the other metal member is overlapped with the overlapped portion. A plurality of holes extending from the member to at least the middle of the one metal member are formed at intervals along the end, and a mechanical joining means is provided in the hole, and at least a gap between the superposed metal members is closed. A molten metal brazing layer is formed.

In the airtight joint according to the present invention, in addition to the above structure, the other metal member is used as a backing plate, and another metal member is abutted against an end of the one metal member superposed thereon. Along with the other metal member and joined by mechanical joining means, forming a molten metal brazing layer that closes the gap between at least the other metal member and the another metal member overlapped, Is also good.

[0011] A molten metal brazing layer may be formed to close the gap between the mechanical joining means and the metal member.

It is preferable that at least one of the metal members is a group IV active metal or a hardly fusible metal having a melting point of 2000 ° C. or higher.

Preferably, the mechanical joining means is a rivet, a bolt or a bolt and nut.

The mechanical joining means is preferably a group IV active metal or a hardly fusible metal having a melting point of 2000 ° C. or higher.

It is preferable that at least one of the superposed metal members is made of molybdenum or a molybdenum alloy.

Further, it is preferable that the molten metal brazing layer is a Ru (ruthenium) -Mo eutectic alloy.

[0017] The Ru-Mo eutectic alloy may contain boron.

In the present invention, the following definitions are assumed.

Difficult-to-melt metals: Mo, W, Ru, Os (osmium), Ta, Nb, their alloys or the following super heat-resistant alloys having a melting point of 2000 ° C. or more.

Super heat resistant alloy: Fe (iron) base (Fe-Ni
Base), Ni (nickel) base, Co (cobalt) base, and a high-temperature high-strength alloy in which high-temperature strength is improved by precipitation of intermetallic compounds and dispersion of oxides and carbides.

Group IV active metals: Ti, Zr, Hf (hafnium), and alloys thereof.

The hole in which the mechanical joining means is provided may be a communication hole that penetrates one metal member and another metal member, or may be a hole that does not penetrate one metal member and reaches only halfway. In short, it may be formed according to the type of mechanical joining means. Of course, when a male screw is used as the mechanical joining means, a female screw is formed in the hole.

Method for forming molten metal brazing layer: Foil or rod-shaped brazing material is directly formed by an ordinary method in an inert gas atmosphere such as Ar (argon), a reducing gas atmosphere such as hydrogen gas, a vacuum atmosphere, or the air. A molten metal brazing layer may be formed by heating and melting, or a paste-form brazing material may be applied and a molten metal brazing layer may be formed by a backside heating method. The backside heating method is a method of heating from the back side or side surface of one of the metal members, and particularly when using a backing plate, a method of heating from the back side of the backing plate. This method uses molybdenum conventionally performed in an inert gas atmosphere, a reducing gas atmosphere or a vacuum atmosphere,
There is an advantage that the brazing of tungsten and their alloys can be performed in the atmosphere.

The present invention is a joint having sufficient strength and hermeticity for applying a hardly meltable metal such as molybdenum or tungsten having excellent high-temperature strength to a structure such as a container.
In other words, the joint is a joint having mechanical strength, and airtightness maintained by brazing the mechanically fastened portion, and having a combined function of both strength and airtightness.

Joining by mechanical fastening with rivets, bolts, bolts and nuts can provide the same strength as the base material by designing appropriate joints based on past results, and can be used in large containers. It is possible. However, the airtightness of a gas seal or the like is insufficient. Therefore, brazing is applied to the mechanical fastening portion, and the gap between the rivet or bolt and the material, and the gap between the materials are continuously filled with the brazing material, thereby providing airtightness.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a structure in which rivets and brazing are combined as an example of the joint of the present invention, and the structure will be described in order.

(1) A predetermined rivet hole 4 is formed in each of the base materials 1 and 2 made of a metal member to be fastened and the backing plate 3 made of a metal member.

(2) The periphery of the rivet hole, which is the upper and lower surfaces of the joint, is also cut.

(3) The rivet 5 having one rounded end, the base materials 1 and 2 and the backing plate 3 are sufficiently heated. The heating temperature varies depending on the material, but is set to be equal to or higher than the temperature at which each material has ductility.

(4) In the heated state, the rivet 5 is passed through the rivet holes 4 of the base materials 1 and 2 and the backing plate 3, one end of the rounded end is fixed with a jig, and the other end is hammered and rounded. Fix with rounding tool. FIG. 1 shows this state.

(5) Gap between base materials 1 and 2 and rivet 5
A brazing material 6 is applied to the surroundings and heated to a predetermined temperature. Then, as shown in FIG. 2, the brazing material flows into the rivet portion and the base material gap portion, and there is almost no void, and a very good joining state is obtained.

Here, as the brazing material, a material which does not cause problems such as embrittlement and evaporation at a use temperature and a use atmosphere may be selected, and there is no particular limitation. For example, Ru-Mo eutectic alloy brazing material can be used for molybdenum which is widely used as a structural material among hardly fusible metals. Ru-Mo
The composition range of the brazing material can be 33.5 to 49.5% by weight of Ru. The Ru-Mo brazing material has a Ru-Mo eutectic structure in this range, and further has a eutectic point of 43%.
% By weight Ru-57% by weight Mo is desirable. Furthermore, Ru-
By adding 2.8% by weight of B (boron) to the Mo eutectic alloy brazing material, it is possible to lower the melting point from 1955 ° C. to 1600 ° C. The problem is significantly reduced.

Further, the joint may be formed as shown in FIG. 3 by directly overlapping the base materials 1 and 2 without using the backing plate 3. In this case, similarly to the above, after the rivet 5 is fixed to the rivet hole 4, the gap between the base materials 1 and 2, that is, the corner formed by the end of the base material 1 and the upper surface of the base material 2 (filled portion). Then, the brazing material 6 is applied around the rivet 5 and heated to a predetermined temperature.

Further, the molybdenum base material and the backing plate are made of a lanthanum-containing molybdenum plate (Japanese Patent Publication No. 2-3865).
9 is disclosed). The rivet is also made of a lanthanum-containing molybdenum rod (JP-B-3-22460).
To be disclosed). The lanthanum-containing molybdenum is composed of lanthanum or lanthanum oxide in an amount of 0.1 to less than 1.0% by weight, and the remainder is molybdenum, and exhibits an interlocking structure that extends in a substantially constant direction and is recrystallized. It is a molybdenum alloy having crystal grains and having excellent workability and high-temperature deformation resistance. By using this lanthanum-containing molybdenum for a structure used at a high temperature, the amount of deformation at a high temperature can be made smaller than when pure molybdenum is used.

As a method of obtaining corrosion resistance relatively inexpensively in chemical equipment, a method of obtaining a non-melting metal such as Nb or Ta or T
A clad material of a combined material of active metals such as i and Zr and a steel material such as stainless steel constituting a base material is often applied. In this case, when joining the clad materials by the fusion welding method, a region where both materials on the base material side and the joining material side melt together is generated, and a fragile intermetallic compound is generated. It is necessary to melt each side independently, which complicates construction.

In this case, the strength and the airtightness of the joint can be obtained by using a rivet or bolt made of a composite material metal or an alloy thereof and using, for example, a silver braze as the brazing material.

The base material is not limited to the above-mentioned materials. Depending on the range of the temperature limitation, various types of Inconel-based alloys, SUS-based iron-based alloys and their clad materials, or other materials may be used. The joint combining mechanical fastening and brazing makes it possible to achieve both strength and airtightness of the joint.

As described above, according to the present invention, a joint having a composite function in which the strength is secured by the mechanical joining means and the airtightness is secured by brazing to the portion of the mechanical joining means is then simplified. Can be provided by construction. For example,
Refractory metals such as molybdenum and active metals such as Ti and Zr as base materials, and 41.7Ru-55.5Mo as brazing materials
By using -2.8B, a structure that can be used even at 1500 ° C. in a reducing and inert atmosphere can be manufactured. Further, the bonding of the clad material made of the above-mentioned metal becomes possible.

[0039]

【Example】

Example 1 In the structure shown in FIG. 1, a Mo plate having a thickness of 1.5 mm was used for the base materials 1 and 2 and the backing plate 3, and a rivet 5 was 3 m in diameter.
m Mo rivet, and the gap between the base materials 1 and 2 is 2 mm
Then, a rivet joint was manufactured.

4 around the gap between the base materials 1 and 2 and the rivet 5
1.7% by weight Ru-55.5% by weight Mo-2.8% by weight
After applying a paste in which isobutyl methacrylate was added as a binder to the brazing filler metal powder prepared in B, the temperature was raised to 1650 ° C. at a rate of 15 ° C. per minute in an Ar atmosphere, and held at this temperature for 10 minutes. Slow cooling was performed to complete the joining.

After this joining process, as shown in FIG. 2, it was confirmed that the brazing material sufficiently flowed in the rivet portion and the gap between the base materials, there were almost no voids, and a very good joining state was obtained. . Further, it was confirmed that the rivet portion and the base material were not damaged.

Example 2 As in Example 1, in the structure shown in FIG.
2, and stainless steel (plate thickness 1.0 mm) for backing plate 3
And a Ti (plate thickness 0.5 mm) clad plate
The rivet 5 was formed with Ti rivets having a diameter of 4 mm and the gap between the base materials 1 and 2 was set to 2 mm.

A paste is prepared by adding isobutyl methacrylate as a binder to a commercially available Ni-containing silver solder (BAg-21) powder in the gap between the base materials 1 and 2 and around the rivet, and then applying the paste in a vacuum atmosphere every minute. 8 at a speed of 20 ° C
The temperature was raised to 50 ° C., kept at this temperature for 10 minutes, and then gradually cooled to complete the joining.

After the joining process, it was confirmed that the brazing material sufficiently flowed around the rivet and the gap between the base materials, there was almost no void, and a very good joining state was obtained. Further, it was confirmed that there was no damage around the rivet and the base material.

Example 3 A Mo plate having a width of 100 mm, a length of 312 mm and a thickness of 3 mm was bent into a cylinder having an inner diameter of 100 mm and a length of 100 mm, and a width of 30 mm and a length of 70 mm in the direction of the outer peripheral axis of the joint.
A Mo plate having a thickness of 3 mm was separated by 15 mm at both ends and joined with a rivet joint to produce two cylinders. Furthermore, width 30mm
A Mo ring having an inner diameter of 106 mm and a thickness of 3 mm was joined by a rivet joint to produce a cylinder having an inner diameter of 100 mm and a length of 200 mm. Further, the base material 2 is joined to the stainless steel flanges 14 having a thickness of 15 mm at both ends by joints having the structure shown in FIG.
(See FIG. 5), and joined by a screw hole 4 'and a bolt 5'. Bolts 5 'are made of Mo with a diameter of 3mm and the interval is 20mm
And

After the flange was joined, the gap was adjusted to 41.7% by weight, Ru-55.5% by weight, Mo-2.8% by weight B from the inside of the cylinder around the gap at the plate joint and around the rivets and bolts as in Example 1. After applying a paste made by adding isobutyl methacrylate as a binder to the brazing filler metal powder, the temperature is raised to 1650 ° C. at a rate of 15 ° C. per minute in an Ar atmosphere, and then maintained at this temperature for 10 minutes, followed by slow cooling. Joining completed.

According to the method shown in FIG. 5, an airtight test of the completed cylindrical container 11 was carried out by increasing the air pressure to 0.5 kgf / cm ² . As a result, no decrease in internal pressure was observed even after 1 hour. The cylindrical container 11 has flanges 14 at both ends, and the flanges 14 are closed by blind plates 13. Pressurization in the cylindrical container 11 is performed by introducing compressed air through a pipe of a valve 16 by a compressor 15 from a hole provided in one of the blind plates 13. 17 is a pressure gauge.

Example 4 In the structure shown in FIG. 1, a Mo plate having a thickness of 1.5 mm was used for the base materials 1 and 2 and the backing plate 3, and a rivet 5 was 3 m in diameter.
m Mo rivet, and the gap between the base materials 1 and 2 is 2 mm
Then, a rivet joint was manufactured.

4 around the gap between the base materials 1 and 2 and the rivet 5
1.7% by weight Ru-55.5% by weight Mo-2.8% by weight
After applying a paste in which isobutyl methacrylate was added as a binder to the brazing filler metal powder prepared in B, the mixture was heated in the air using an oxygen-acetylene burner and a TIG welding torch from the back side of the joint, that is, the backing plate 3 side. And bonding was performed (backside heating method).

After this bonding treatment, it was confirmed that the brazing material sufficiently flowed through the rivet portion and the gap between the base materials by using any of the heating methods, that there were almost no voids, and that a very good bonding state was obtained. . Further, it was confirmed that the rivet portion and the base material were not damaged.

Example 5 In the structure shown in FIG. 1, a 1.5 mm-thick lanthanum-containing molybdenum plate (JP-B-2) was used for the base materials 1, 2 and the backing plate 3.
38659) and the rivet 5 has a diameter of 3 mm.
The rivet joint was manufactured by using a lanthanum-containing molybdenum rod (disclosed in Japanese Examined Patent Publication No. 3-22460) and setting the gap between the base materials 1 and 2 to 2 mm.

4 around the gap between the base materials 1 and 2 and the rivet 5
1.7% by weight Ru-55.5% by weight Mo-2.8% by weight
After setting the B-sintered brazing rod, 1 minute per minute in Ar atmosphere
The temperature was raised to 1650 ° C. at a rate of 5 ° C., held at this temperature for 10 minutes, and then gradually cooled to complete the joining.

The sintered brazing filler used here was prepared by adding 8% by weight of liquid paraffin as a binder to the above brazing filler metal powder, kneading the mixture, extruding it to a diameter of 1 mm, and sintering it at 1400 ° C. in vacuum. However, there is no problem even if the material is processed under these conditions. For example, any material may be used as long as it can be handled at the time of use with a binder having no harmful residual carbon after sintering and sintering conditions.

After the joining process, as shown in FIG. 2, it was confirmed that the brazing material sufficiently flowed in the rivet portion and the gap between the base materials, that there were almost no voids, and that a very good joining state was obtained. . Further, it was confirmed that the rivet portion and the base material were not damaged.

In each of the above embodiments, rivets and bolts are used as mechanical joining means, but it goes without saying that bolts and nuts may be used.

Comparative Example 1 As in Example 3, Mo plates were joined by rivets to produce a cylinder having an inner diameter of 100 mm and a length of 200 mm. An airtightness test was performed in the same manner as in Example 3 with only the rivet joined. As a result, the pressurized air leaked in 5 seconds, and the internal pressure became 0 kgf / cm ² .

Comparative Example 2 As in Example 3, Mo plates were joined by rivets, and
A cylinder of 0 mm × 200 mm in length was manufactured. Further, Mo was sprayed on the rivet joint and its surroundings by plasma spraying. In this (rivet bonding + spraying) state, an airtight test was performed in the same manner as in Example 3. as a result,
In 30 seconds, the pressurized air leaked and the internal pressure became 0 kgf / cm ² .

Although some preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and includes various modifications. For example, in the formation of the molten metal brazing layer that closes the gap between the metal members in which the base materials 1 and 2 and the backing plate 3 are overlapped, in the example of FIG. Of the superposed portion (that is, the backing plate 3)
The molten metal brazing layer was formed in all of the gap between the base material 1 and the backing plate 3 and the base material 2) and the gap between the butted portions of the base materials 1 and 2. What is necessary is just to form in the gap of the overlap part of the backing plate 3 and the base materials 1 and 2, or the gap of the butted part of the base materials 1 and 2.

Further, the mechanical joining means, that is, the holes through which rivets or bolts are inserted, inserted or screwed, are formed from the upper base material 1 to the lower backing plate 3 in FIG.
May be formed so as to extend from the upper base material 1 to at least halfway of the lower base material 2, and further, from the lower backing plate 3 or the base material 2 to at least halfway of the upper base material 1. It may be formed so as to reach. In this case, it may not be necessary to form a molten metal brazing layer that closes the gap between the mechanical joining means and the base materials 1, 2 or the backing plate 3 for airtightness. For example, in FIG. 2, the base materials 1 and 2 are located inside the container,
When a hole is formed from the inner base materials 1 and 2 to the middle of the backing plate 3 outside the container, or the base materials 1 and 2 are located outside the container, and the base materials 1 and 2 In the case where a hole reaching the middle of the backing plate 3 inside the container is formed, it is necessary to form a molten metal brazing layer that closes the gap between the mechanical joining means and the base materials 1 and 2 in order to make the inside of the container airtight. There is. Conversely, in FIG. 2, when the base materials 1 and 2 are located inside the container and holes are formed from the backing plate 3 outside the container to the middle of the base materials 1 and 2, Is formed on the outside of the container, and a hole is formed from the inner backing plate 3 to the middle of the base materials 1 and 2 on the outside of the container. It is not necessary to form a molten metal brazing layer that closes the gap with the plate 3. This is the same in FIG. Note that the base materials 1 and 2 described above with reference to FIG. 2 are located inside the container, and a hole extending from the inner base materials 1 and 2 to the middle of the backing plate 3 outside the container, Even when holes 1 and 2 are located outside the container and holes are formed from the outer base materials 1 and 2 to the middle of the backing plate 3 inside the container, the gap between the butted portions of the base materials 1 and 2 is also formed. Instead of forming a molten metal brazing layer that closes the gap, a molten metal brazing layer that closes the gap is formed in each gap between the overlapped metal members of both ends of the backing plate 3 and the base materials 1 and 2. That is, the brazing material 6 is applied to each corner (filled portion) formed between both end portions of the backing plate 3 and the lower surfaces of the base materials 1 and 2 and heated to a predetermined temperature. If a molten metal brazing layer is formed in each gap between the upper surfaces of both ends and the lower surfaces of the base materials 1 and 2, a mechanical seal is required to make the container airtight. There is no need to form a molten brazing metal layer to close the gap between the coupling means and the backing plate 3.

[0060]

The joint of the present invention is a joint which can be used for a hardly meltable metal member or a group IV active metal member. That is, the strength is secured by the mechanical joining means,
The gap between the mechanical coupling means and the metal member, and the gap between the superposed metal members are closed by brazing molten metal to ensure airtightness, so that a hardly fusible metal member or a Group IV active metal member, etc. Unprecedented strength and airtightness can be ensured without impairing the inherent characteristics that it can be used under severe conditions. Therefore, by using the joint of the present invention, it is possible to easily manufacture a structure such as a container that requires strength and airtightness, which could not be manufactured with a hardly fusible metal member or a Group IV active metal member in the past. Can be.

[Brief description of the drawings]

FIG. 1 is a sectional view for explaining an airtight joint of the present invention.

FIG. 2 is a cross-sectional view showing an example in which base materials are joined together according to the present invention.

FIG. 3 is a cross-sectional view showing another example in which base materials are joined together according to the present invention.

FIG. 4 is a sectional view showing still another example in which base materials are joined together according to the present invention.

FIG. 5 is a diagram showing an apparatus used for an airtight test.

[Explanation of symbols]

 1, 2 base material 3 backing plate 4 rivet hole 4 'screw hole 5 rivet 5' bolt 6 brazing material 11 cylindrical container 13 blind plate 14 flange 15 compressor 16 valve 17 pressure gauge

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kohei Ikegami 1-9-3 Kamata Honcho, Ota-ku, Tokyo Inside Niigata Ironworks Engineering Center Co., Ltd. (72) Inventor Yoshiaki Watanabe Isogo, Yokohama-shi, Kanagawa 27, Shinisogo-cho, Ward Inside Niigata Ironworks Development Center Co., Ltd.

Claims (9)

[Claims] 1. An end portion of one metal member is overlapped with an end portion of another metal member, and a hole extending from the other metal member to at least halfway of the one metal member is formed in the overlap portion. Airtight joint, wherein a plurality of holes are formed at intervals along the portion, a mechanical joining means is provided in the holes, and a molten metal brazing layer is formed to close at least the gap between the superposed metal members. . 2. The machine according to claim 1, wherein the other metal member is a backing plate, and another metal member is abutted against an end of the one metal member overlapped with the other metal member and overlapped with the other metal member. 2. The hermetic joint according to claim 1, wherein a molten metal brazing layer is formed, which is joined by a mechanical joining means, and closes a gap between the at least one other metal member and the another metal member. 3. The airtight joint according to claim 1, wherein a molten metal brazing layer is formed to close a gap between the mechanical joining means and the metal member. 4. At least one of said metal members has a melting point of 2.
The hermetic joint according to any one of claims 1 to 3, wherein the hermetic joint is a hardly meltable metal having a temperature of 000 ° C or higher or an active metal belonging to Group IV. 5. The apparatus according to claim 1, wherein said mechanical joining means is a rivet, a bolt or a bolt nut.
5. The airtight joint according to any one of 4. 6. The hermetic joint according to claim 4, wherein the mechanical joining means is a hardly fusible metal having a melting point of 2,000 ° C. or more, or a group IV active metal. 7. The airtight joint according to claim 6, wherein at least one of the superposed metal members is made of molybdenum or a molybdenum alloy. 8. The hermetic joint according to claim 7, wherein the molten metal brazing layer is a Ru—Mo eutectic alloy. 9. The airtight joint according to claim 8, wherein the Ru—Mo eutectic alloy contains boron.