JP2642386B2 - Vacuum valve and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a vacuum valve and a method of manufacturing the same, and particularly, hermetically seals a ceramic container and a metal lid using a metal braze. The present invention also relates to a vacuum valve formed with a vacuum container and a method for manufacturing the same.

(Prior Art) Generally, a vacuum valve comprises a ceramic container 1 formed in a cylindrical shape as shown in FIG. 3, and sealing portions 2a, 2 at both ends thereof.
A vacuum container is formed in a vacuum-tight manner by metal lids 3a and 3b provided through a pair of b. A pair of contacts attached to opposed ends of the fixed conductive shaft 4a and the movable conductive shaft 4b in the vacuum container. 5a, 5b
Are provided, and the contact 5a is a fixed contact and the contact 5b is a movable contact. The other ends of the fixed conductive shaft 4a and the movable conductive shaft 4b are a fixed terminal 6a and a movable terminal 6b, respectively. Further, a bellows 7 is attached to the movable conductive shaft 4b of the movable contact 5b.
Is attached, and the movable contact 5b can be moved in the axial direction while keeping the inside of the vacuum container vacuum-tight. A metal arc shield (not shown) is provided above the bellows 7 to prevent the bellows 7 from being covered with the arc vapor. Reference numeral 8 denotes a metallic arc shield provided in the vacuum vessel so as to cover the contacts 5a and 5b, and prevents the ceramic vessel 1 from being covered with arc vapor. Further, the contacts 5a and 5b are directly brazed to the fixed conductive shaft 4a and the movable conductive shaft 4b, respectively, or brazed via electrodes (not shown).

In such a vacuum valve configuration, when the ceramic container 1 and the metal lids 3a and 3b are joined via the sealing portions 2a and 2b, generally, a metallized layer (for example, Mo-Mn), and silver brazing is performed via the metallized layer.

That is, conventionally, as a method of joining ceramics, a method in which a ceramic is first metallized and then brazed to a metal has been mainly used. As a metallizing method, the following method is known.

(1) A method in which a powder containing Mo or W as a main component is applied to the surface of a ceramic base material, and heated to, for example, 1400 to 1700 ° C. in a reducing atmosphere to react with the ceramic base material and metallize. Is plated with Ni or the like.

(2) A method of arranging Au or Pt on the surface of a ceramic base material and heating while applying pressure to perform metallization.

(3) An active metal such as Ti or Zr and N
A method in which transition metals such as i and Cu are arranged and heat treated at a temperature higher than the melting point of those alloys for metallizing.

And so on.

As described above, in a general vacuum valve, the ceramic container 1 which forms a vacuum container together with the metal lids 3a and 3b is used.
It is indispensable to join the metal lids 3a and 3b in a vacuum-tight manner, and to provide a metallized layer at the joint, and to improve the wettability with the silver brazing material if necessary on the surface of the metallized layer. Therefore, a plating treatment of Ni or the like and a heat treatment of the plating layer of Ni or the like are performed.

(Problems to be Solved by the Invention) However, the method (1) has a problem in a complicated process such as a process at a very high temperature for metallizing. Further, in the method (2), an expensive noble metal is used. Therefore, a vacuum valve having a large joint area requires a high pressure for the purpose of increasing the adhesion in addition to the problem of economy, and the productivity ( The pressurized parts for obtaining pressure take up some space in the brazing furnace).

On the other hand, in the above method (3), the active metal wets the ceramic base material, so that almost no pressure is required, and with the effect of the active metal, the active metal has strong adhesion to the ceramic base material.
Where the metallization can be metallized and the ceramic and metal members overlap sufficiently, the silver braze shows good bonding, but the brazing material is placed on the part without metal members, i.e. simply on the surface of the ceramic. In such a portion, there is a problem that metallization is not satisfactorily performed, and a vacuum valve with good airtightness cannot be obtained.

As described above, in any of the above (1), (2), and (3), after metallizing, a metal member for sealing necessary to maintain the airtightness inside the vacuum valve is used. There is a problem that it is necessary to join and the process becomes complicated.

Furthermore, in joining a ceramic container of a vacuum valve to a metal lid, a joining technique using a brazing material melts the brazing material at the time of joining, and fills a gap at a joining portion with the brazing material to improve adhesion with the member. It is used in a wide range of applications because it keeps good and does not require pressurization at the time of bonding and is simple in process. Particularly in the joining of dissimilar materials, the members react greatly to each other as in the case of diffusion welding or fusion welding, so that an alloy layer is not generated, and therefore, the strength reduction due to the brittleness of the generated alloy layer is small. There are benefits. However, depending on the combination of members, when the brazing material is melted, the constituent elements of the member are rapidly diffused into the brazing material, and as a result, a reaction between those elements or a reaction with the constituent elements in the brazing material is caused. There is also a problem that a harmful alloy layer may be generated.

The present invention has been made in view of the above problems,
The purpose is that metallizing and airtight joining can be performed at the same time instead of brazing after metalizing the joining surface of the conventional ceramic member in advance, which is extremely useful in terms of reliability and economy. To provide a simple vacuum valve.

Another object of the present invention is to provide a vacuum valve having improved reliability by preventing the formation of a harmful layer and preventing a silver brazing component from entering a ceramic container or a metal lid when joining the ceramic container and the metal lid. It is to provide a manufacturing method of.

[Configuration of the invention]

(Means for Solving the Problems) As a result of repeated studies to achieve the above object,
The joining surface between the ceramic container of the vacuum valve and the metal lid for sealing is finished to a surface roughness of 0.1 to 10 μm, and at least one surface has an activity of Ti or / and Zr having an average particle size of 1 to 10 μm. 0.1-1 metal or their mixed powder
Pre-applied in an amount of 0 mg / cm ^2, further by heating interposed or contacting the metal brazing material between the coating layer and the metal lid, easily airtightly and ceramic container and the metal lid It is what joins well. In particular, a brazing material for joining is placed between the ceramic container and the metal lid, and an intermediate material made of Fe or / and Cr is interposed between the two brazing materials to form a highly reliable vacuum valve. Thus, the present invention has been completed. That is, the present invention forms a vacuum container by closing both end openings of a cylindrical ceramic container with a metal lid, and disposes a pair of contacts that can be freely contacted and separated inside the vacuum container. A vacuum valve comprising an arc shield for preventing evaporated metal from a contact from adhering to the inner surface of the ceramic container,
An active metal layer made of at least one of Ti and Zr in an amount of 0.1 to 10 mg / cm ^{2 on} at least a joining surface of the ceramic container of a pair of joined objects composed of the ceramic container and the metal lid. After adhering, a brazing material for joining each of the members to be joined is arranged so as to be in contact with the members to be joined, and Fe and Cr
A vacuum valve, wherein an intermediate material made of at least one of the above materials is interposed and the brazing material is melted.

Further, the present invention provides a vacuum container by closing both ends of a cylindrical ceramic container with a metal lid, and disposing a pair of contacts that can be freely contacted and separated inside the vacuum container. In a vacuum valve having an arc shield for preventing metal evaporated from a contact point from adhering to an inner surface of the ceramic container, at least the ceramic container of a pair of joined bodies composed of the ceramic container and the metal cover A first step of obtaining a finish processing surface having a surface roughness of 0.1 to 10 μm,
A second step of adhering an active metal consisting of at least one of Ti and Zr in an amount of 0 mg / cm ² , between the pair of objects, a brazing material for each object to be bonded; It is arranged so as to be in contact with the workpiece and between these brazing materials.
A third step of interposing an intermediate material made of at least one of Fe and Cr, and a fourth step of heating the inside of the vacuum vessel during or after evacuation to join the pair of members to be joined. A method for manufacturing a vacuum valve, comprising the steps of:

 The embodiment is as follows.

(1) In the fourth step, after evacuating the inside of the vacuum container,
The ceramic member and the metal member are sealed.

(2) In the fourth step, the ceramic member and the metal member are sealed while the inside of the vacuum vessel is evacuated.

(3) In the fourth step, the ceramic member and the metal member are bonded in advance in a non-oxidizing atmosphere, and then the inside of the vacuum vessel is evacuated.

(Operation) As described above, according to the present invention, the ceramic container and the metal lid perform metallizing and hermetic bonding simultaneously without metallizing the ceramic container in advance,
There is no intrusion of the silver brazing material into the ceramic container or the metal lid, so that the manufacturing process can be simplified and a vacuum valve having high joining reliability can be obtained.

(Example) Hereinafter, an example of the present invention will be described. As described above, in the vacuum valve, the metal lid is connected to the ceramic container.

However, in general, the thermal expansion coefficients of ceramics and metals are significantly different, so that a considerable amount of thermal stress is generated at the joint due to the difference between the two. These thermal stresses have an important problem that cracks are easily generated in ceramics. Therefore, in order to reduce the occurrence of such thermal stress, a joined body using a metal having a thermal expansion coefficient close to that of ceramics has been studied as much as possible. The metal used for such a purpose is used as the lid. That is, generally, 42 alloy (42% Ni-Fe), Kovar (KOV 29% Ni-17Co-Fe) or the like is used as a metal lid for a vacuum vessel of a vacuum valve.

When joining these iron-based low thermal expansion alloys, if an Ag-based brazing material used for joining ordinary ceramics and metals is used, the components of the brazing material will easily penetrate (penetrate) around the grain boundaries, and This may cause the lid to deteriorate.

Therefore, in order to prevent this, for example, Weld J, 61-11, P3
As shown in Fig. 63, an attempt has been made to provide a Ni plating layer on the joining layer surface of an iron-based low thermal expansion alloy, but in this case, Ni diffuses into the brazing material and adversely affects the bondability between the ceramic and the brazing material. The effect was confirmed by experiments. This problem has been a serious drawback particularly when joining is performed to obtain a container or the like that protects airtightness.

Next, an embodiment of the present invention will be described in detail with reference to FIG. 1 and FIG.

Examples 1-3, Comparative Examples 1-2 As shown in FIG. 1, the outer diameter is 124 mm, the inner diameter is 110 mm, and the height is 170 m.
The end surfaces 10a and 10b of the m ₂ Al ₂ O ₃ ceramic container 10 were adjusted by polishing to have a surface roughness of 0.5 μm.

Next, a Ti powder having an average particle diameter of 3.5 μm is prepared. A mixture of the above-mentioned Ti powder in an ethyl alcohol solution of polyvinyl alcohol (binder) is passed through end faces 10a and 10b having the above surface roughness, for example, through a metal mesh,
Ti (active metal) powder was uniformly applied so that the applied amount was 1 mg / cm ² to form a Ti-coated surface 11 shown in FIG.

After a silver solder 12 having a thickness of 0.2 mm is placed on the Ti-coated surface 11, an intermediate material 14 (Example 1) made of Fe and having a thickness of 10 μm is brought into contact with the silver solder 12. Furthermore, a silver solder (for example, a 72% Ag-Cu alloy) for the metal lid 3a made of a 42% Ni-Fe alloy 13
Are arranged so that they have the configuration shown in FIG. Then, vacuum degree 2 × 10 ^-5 Torr, temperature 850 ° C., time 6
Under different conditions, the silver braze 12 is melted and the Ti
The ceramic container 10 and the metal lid 3a were sealed via the coating surface 11.

Immediately after cooling, the degree of vacuum in the sealed vacuum vessel was measured, and a level of 1 × 10 ⁻⁷ Torr was secured.

Under such conditions, the thickness of the intermediate member 14 was set to 2 μm (Comparative Example 1), 150 μm (Example 2), 800 μm (Example 3), and a configuration not using the intermediate member 14 (Comparative Example 2). The same treatment as in No. 1 was performed, and the ceramic container 10 and the metal lid 3a were joined. When the joining strengths were measured, they all showed 30 kg / mm ² as shown in Table 1. However, when there was no intermediate material 14 (Comparative Example 1), the silver brazing used in the silver brazing treatment was used. In some samples, the Ag component penetrated into the grain boundaries of the metal lid 3a, and the sample itself was leaked by a leak test using He, which was not preferable in terms of reliability. Further, even when the thickness of the intermediate material 14 was 2 μm (Comparative Example 2), the phenomenon of Ag bleeding was observed, which was not preferable in terms of reliability. However, intermediate material 14
When the thickness is 10 μm or more (Examples 1 to 3),
The airtightness and the degree of Ag uptake were within the allowable range.
From these results, it was found that the presence of the intermediate member 14 is important for maintaining the overall reliability of the vacuum valve, and in particular, the thickness thereof needs to be 10 μm or more.

Examples 4 to 5 and Comparative Example 3 However, the above conclusions are particularly concluded that the surface finish roughness of the end face 10a or 10b of the ceramic container 10 is 0.5 μm, the particle size of the Ti (active metal) powder is 3.5 μm, Is 1 mg / cm ^2, and especially when these conditions do not satisfy the prescribed conditions, airtightness and bonding strength are affected, so from the viewpoint of securing overall reliability, Intermediate material mentioned above
Need to control at the same time as the management of 14 thickness. That is, when the material of the intermediate material 14 is Fe and its thickness is 10 μm, and when the surface roughness of the end face 10a or 10b of the ceramic container 10 is 0.1 to 10 μm (Examples 4 and 5),
While the overall properties including the joint strength are good,
When the thickness was 50 μm (Comparative Example 3), both the airtightness and the bonding strength were lower than those of Examples 4 and 5. Incidentally, the penetration phenomenon of the silver brazing into the metal lid grain boundaries is very small due to the effect of the presence of the intermediate material 14 as in the first to third embodiments.

When the surface roughness of the end face 10a or 10b of the ceramic container 10 is smaller than 0.1 μm (Example 1), the economic value is reduced. Therefore, the surface roughness of the end face 10a or 10b of the ceramic container 10 is substantially 0.1 to 10 μm.
It is necessary to select a range of m.

Examples 6 to 9 and Comparative Examples 4 to 6 The thickness of the Ti coating surface 11 also affects the airtightness and the bonding strength. That is, if the thickness is in the range of 1 to 10 μm (Examples 6 and 7), there is no problem overall, but if the thickness is 44 μm (Comparative Example 4), the bonding strength is 30 kg / mm ^2. Although the above could be secured, a leak was observed.

Further, when the adhesion amount of the Ti-coated surface 11 was also 0.01 mg / cm ² , both the joining strength and the airtightness were remarkably inferior, and 0.1 to 10 mg / cm ² (Example 8,
9) was within the preferable range, and when the amount was too large, problems were also found in the leak characteristics and the bonding strength. Therefore, the adhesion amount of the Ti-coated surface 11 was set to 0.1 to 10 mg / cm ^2, and a good overall bonding state was obtained by using an intermediate material under predetermined conditions.

Embodiments 10 to 14 The embodiments 1 to 9 described above are used as the material of the Ti coating surface 11.
Although the example of Ti has been described, the present invention is not limited to Ti, but Zr
(Example 10) and Ti-Zr (Example 12) also provided favorable effects overall.

Although the example of Fe as the material of the intermediate material 14 has been described, it was recognized that the present invention is also effective for Cr in addition to Fe (Examples 11 to 14).

Furthermore, as a metal lid 3a or 3b, 42 alloy (42%
There is no problem even if a material other than Ni-Fe) is used (Kovar in Example 14).

Note that the withstand voltage characteristics are such that the fixed contact 5a and the movable contact 5b of the vacuum valve are opened by 10 mm, and a voltage of 30 KVAC is applied between the above contacts.
It was applied to investigate the presence or absence of flashover. Tables 1 and 2 show the case where discharge occurred between the contacts while the applied voltage was rising to 30 KV as flashover, and the case where there was no discharge at 30 KV for 1 minute as good. The examples were all good and no problem.

Further, as for the method of applying the active metal powder to the ceramic container, the same effect can be obtained by an evaporation method such as ion plating in addition to the method described above.

In the above-described embodiment, the case where the ceramic member and the metal member are joined at the same time as the inside of the vacuum valve is evacuated (or while the inside is evacuated) is shown. It is also possible to evacuate the inside with an exhaust pipe, etc. On the contrary, it is also possible to perform joining after the vacuum valve placed in the vacuum tank is sufficiently evacuated, and all have the same effect Can be selected as appropriate.

When the method of exhausting after joining both members in advance is selected, the joining atmosphere of both members may be not only the vacuum atmosphere described in the above embodiment but also an inert gas (for example, hydrogen).

Further, in the above-described embodiments and comparative examples, the active metal powder is applied through, for example, a metal mesh as a means for applying the active metal powder. However, the same result can be obtained by applying the above-mentioned predetermined amount by sputtering, ion plating or the like. .

〔The invention's effect〕

Since the present invention is configured as described above, it does not require metallizing to a ceramic member, which has been conventionally performed in a separate process, and simplifies the manufacturing process by performing it at the same time, thereby improving reliability and economy. A vacuum valve can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a ceramic container according to one embodiment of the present invention, and FIG. 2 is a ceramic container, a metal cover, a surface coated with Ti (active metal) powder and silver according to an embodiment of the present invention. FIG. 3 is a cross-sectional view showing an example of a conventional vacuum valve. 3a, 3b: metal lid, 5a: fixed contact 5b: movable contact, 10: ceramic container 11: Ti-coated surface, 12: silver brazing material 13: silver brazing material for metal lid, 14 …… Intermediate material

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shoji Niwa 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Plant, Inc. (56) References JP-A-64-102822 (JP, A) JP-A-62-281218 (JP, A) JP-A 54-177556 (JP, U) JP-A 50-69653 (JP, U)

Claims (2)

(57) [Claims] 1. A vacuum container is formed by closing both ends of a cylindrical ceramic container with a metal lid, and a pair of contacts that can be freely contacted and separated is disposed inside the vacuum container. In a vacuum valve comprising an arc shield for preventing evaporated metal from adhering to the inner surface of the ceramic container, at least the ceramic container of a pair of joined bodies comprising the ceramic container and the metal lid body After an active metal layer made of at least one of Ti and Zr in an amount of 0.1 to 10 mg / cm ² is attached to the joining surface, the brazing material is joined to the respective joining members to join the joining members. A vacuum valve, which is arranged so as to be in contact with the body, and an intermediate material made of at least one of Fe and Cr is interposed between these brazing materials, and the brazing material is melted. . 2. A vacuum container is formed by closing both ends of a cylindrical ceramic container with a metal lid, and a pair of contacts that can be freely contacted and separated is disposed inside the vacuum container. In a vacuum valve comprising an arc shield for preventing evaporated metal from adhering to the inner surface of the ceramic container, at least the ceramic container of a pair of joined bodies comprising the ceramic container and the metal lid body First step of obtaining a finished surface having a surface roughness of 0.1 to 10 μm by joining the bonding surface to 0.1 to 10 mg / cm
^{A second} step of adhering an active metal comprising at least one of Ti and Zr in an amount of ² between the pair of objects to be bonded; And between these brazing materials, Fe and
A third step of interposing an intermediate material made of at least one of Cr and a fourth step of heating the inside of the vacuum vessel during or after the evacuation, and then heating to join the pair of objects to be joined; A method for manufacturing a vacuum valve, comprising: