JP2945466B2 - Airtight joint structure between ceramic tube and metal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an airtight joining structure between a ceramic tube and a metal.

[Conventional technology]

In recent years, in a high-energy beam accelerator called a storage ring, an electron and a positron collide with each other in an ultra-high vacuum state of about 10 ⁻¹⁰ Torr · l / sec.

It is essential that metal parts and members used in such accelerators have low degassing properties under ultra-high vacuum and low residual radioactivity. Recently, aluminum is used which is light in weight and has a residual activity less than an order of magnitude less than stainless steel when used in an accelerator.

In addition, the measurement value of the beam monitor used for grasping the state of the beam under a high frequency voltage in the gigahertz band is based on the fact that it is preferable that there is no metal having a high magnetic susceptibility around the beam monitor. Al or Cu having extremely low magnetic susceptibility is used as a metal material.

Further, in such a high energy beam accelerator, it is necessary to insulate parts of the accelerating tube with a material having a small degassing property and being less susceptible to beam damage, and ceramic such as alumina is used as the insulating material. ing. At this time, it is required that the interior of the accelerator be maintained in a high vacuum state. Therefore, an excellent hermetic joint structure between the ceramic component and the metal, which can highly hermetically join the ceramic component and the metal component, is developed. Is strongly desired.

In the hermetic joining structure between the ceramic component and the metal, Al, Cu, or an alloy containing these metals as a main component is usually used as a metal material for joining with the ceramic for the above-described reason.

FIG. 4 shows an example of a conventionally known hermetic joining structure between a ceramic tube and a metal using a ceramic tube, which is a typical example of the above ceramic parts.

This hermetic bonding structure has a structure in which a metallized layer 3 is provided on an end face 2 of a ceramics (alumina) tube 1 and a metal member 4 is brazed to the metallized layer 3 with a brazing material 5. Another metal part 7 (for example, an Al alloy part) is joined to the metal member 4 via a metal bellows 6. At this time, the joining is performed, for example, by metallizing the alumina end face with Mo / Mn and brazing using a brazing material such as silver brazing.

This conventional hermetic joining structure between a ceramic tube and a metal has a problem that if the inner diameter of the ceramic tube becomes about 60 mm or more in a major axis and about 40 mm or more in a minor diameter, cracks occur frequently on the metallized interface or on the ceramics side. (8 in FIG. 4 indicates the state of occurrence of cracks). The occurrence of the cracks is caused by the difference in the thermal expansion coefficient between the metal part and the ceramic part (for example, the thermal expansion coefficient of Al is 24 × 10 ^-6 / ° C, and the thermal expansion coefficient of alumina is 7 × 10 ^-6 / ° C). This is because the tensile stress generated at the interface exceeds the bonding strength of the interface or the strength of the ceramic. Usually, this tensile stress is generated in a cooling process after the ceramic component and the metal are integrated by heating brazing, and the magnitude thereof is determined by the difference in the coefficient of thermal expansion, the heat treatment temperature, the dimensions of the joined body, and the elasticity of the metal. It is shown as a function of the product of the coefficients, and when the joining material and the brazing temperature are constant, the larger the size of the joined body, the larger the generated tensile stress. The larger the tensile stress (residual stress) remaining in the joined body, the higher the rate of breakage during manufacturing, the lower the yield during manufacturing, and even if it is obtained as a joined body after combining with other parts In the process, the ceramic is frequently damaged.

[Problems to be solved by the invention]

The present invention eliminates the drawbacks of the above-mentioned prior art, can substantially avoid breakage of ceramics during manufacturing and subsequent steps, and can highly highly hermetically join a ceramic tube and a metal part. An object of the present invention is to provide an excellent hermetic joint structure between a ceramic tube and a metal.

[Means for solving the problem]

The hermetic joining structure between the ceramic tube and the metal of the present invention is as follows:
In an airtight joint structure in which a metal sealing member made of Al, Cu or an alloy containing these metals as a main component is brazed to the end of the ceramic tube, the metal sealing member is composed of two members. One end of the member is brazed to the outer periphery of the end of the ceramic tube, one end of the other member is brazed to the inner periphery of the end of the ceramic tube, and the other ends of the two members are in contact with each other. Means.

The hermetic joining structure between the ceramic tube and the metal of the present invention is as follows:
This structure does not generate tensile stress on the ceramics side, can almost avoid breakage of ceramics in the production and subsequent processes, which has frequently occurred with the conventionally known hermetic bonding structure, and has a high degree of connection between the ceramics tube and metal parts. It can be hermetically bonded to

Hereinafter, an airtight joining structure between a ceramic tube and a metal according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view showing an example of an airtight joint structure between a ceramic and a metal according to the present invention.

This airtight joint structure is a ceramic (alumina) tube 1
A metal sealing member made of Al, Cu or an alloy containing these metals as a main component is brazed to the end of the metal sealing member. At this time, the metal sealing member is composed of two members. Metallized layer 3 provided on the outer peripheral side of the end of ceramic tube 1
Then, one end of the other member 9 ′ is brazed to a metallized layer 3 ′ provided on the inner peripheral side of the end of the ceramic tube 1 with the brazing material 5 ′. (9 and 9 ') have a structure in which the other end portions are in contact with each other.

The other ends of the two members may be joined by brazing.

In the hermetic joining structure of the present invention, as shown in FIG. 1, one end of the metal sealing member 9 is brazed to the metallized layer 3 on the outer peripheral side of the end of the ceramic tube 1 by the brazing material 5 to be hermetically sealed. Therefore, the stress applied to the ceramic in the cooling process after heating brazing is a compressive stress, and it is possible to almost avoid breakage of the ceramic at the time of manufacturing and subsequent processes that frequently occur in the above-mentioned conventional hermetic bonding structure, Moreover, the ceramic tube and the metal part can be highly airtightly joined. Further, in the airtight joining structure of the present invention, when brazing the metal sealing member to the outer peripheral side of the end of the ceramic tube, the metal sealing member 9 is usually provided on the outer peripheral portion of the ceramic tube as shown in FIG. Since it is brazed and installed in the recessed portion along the outer periphery thereof, it is also useful for maintaining the strength of the outer periphery of the ceramic tube.

In the hermetic bonding structure of the present invention, one end of the metal sealing member 9 'is brazed to the metallized layer 3' on the inner peripheral side of the end of the ceramic tube 1 with a brazing material 5 'as shown in FIG. Since the ceramic tube is tightly sealed, the inner peripheral end of the ceramic tube and the metal sealing member 9 'can be tightly joined to each other. As a result, the ceramic tube and the metal component can be highly air-tightly joined. . Particularly, in the accelerating tube, since a high-frequency current passes along the inner peripheral surface of the ceramic tube, if there is a gap between the end of the inner peripheral surface of the ceramic tube and the metal sealing member 9 ', this portion is used. In this case, the hermetic bonding structure of the present invention, which highly hermetically seals not only the outer peripheral surface of the end portion but also the inner peripheral surface of the end portion of the ceramic tube, is excellent in this respect.

In the hermetic joining structure between the ceramic tube and the metal according to the present invention, when the metal sealing member is brazed to the inner peripheral side of the end of the ceramic tube, as shown in FIG. The end of the inner peripheral surface of the ceramic tube 1 and the metal sealing member 9 'may be brazed so as to be in contact with each other. Alternatively, as in another example of the hermetic joint structure of the present invention shown in FIG. The sealing member 9 ′ may be brazed and installed in a concave portion provided on the inner peripheral portion of the ceramic tube 1 along the inner peripheral portion.

〔Example〕

 Hereinafter, examples according to the present invention will be described in detail.

FIG. 3 is a cross-sectional view showing one embodiment of an airtight joining structure between a ceramic tube and a metal according to the present invention.

As shown in FIG. 3, an alumina tube (diameter 60 mm, length 300 mm) 10 having a relative density of 98% and a purity of 99.9% was mixed with a predetermined composition (70: 30: 5: 10) and pasted. Ag-Cu-Ni
-Applying and drying Ti, performing metallization at 1150 ° C in a vacuum furnace to provide metallized layers 3 and 3 'on the outer peripheral side and the inner peripheral side of the end of the alumina tube 10, respectively. Oxygen-free Cu using BAg-8 (blow materials 5 and 5 ')
The metal sealing members 11 and 11 ′ made of
And airtightly joined.

Next, metallized layers 12 and 12 'are provided on the other end of the alumina tube 10 on the outer periphery and the inner periphery of the end of the alumina tube 10 in the same manner as above, respectively.
The metal sealing members 14 and 14 'made of A3004 (Al alloy) were brazed at 600 ° C. in a vacuum of 1 × 10 ⁻⁶ Torr, respectively, using the brazing materials (13 and 13 ′) and air-tightly joined.

The ultra-high vacuum ceramic accelerator thus obtained is
It has a vacuum tightness of 10 ^-11 Torr · l / sec, and does not easily break like a conventional ceramic tube.

〔effect〕

According to the hermetic joining structure of a ceramic tube and a metal of the present invention, it is possible to almost avoid breakage of ceramics at the time of manufacturing and subsequent steps, which frequently occurs in the conventional hermetic joining structure, and furthermore, the ceramic tube and metal parts And can be highly airtightly bonded.

[Brief description of the drawings]

1 and 2 are cross-sectional views showing an example of an airtight joining structure between a ceramic tube and a metal according to the present invention. FIG. 3 shows an embodiment of an airtight joining structure between a ceramic tube and a metal according to the present invention. FIG. 4 is a sectional view showing a conventional hermetic joining structure between a ceramic tube and a metal. 1,10 ... Ceramic tube 3,3 ', 12,12' ... Metalized layer 5,5 ', 13,13' ... Raw material 9,9 ', 11,11', 14,14 '... Metal Sealing member

Claims (1)

(57) [Claims] 1. An airtight joint structure in which a metal sealing member made of Al, Cu or an alloy containing these metals as a main component is brazed to an end of a ceramic tube, wherein the metal sealing member is two members. And one end of one member is brazed to the outer periphery of the end of the ceramic tube, and the other end is brazed to the inner periphery of the end of the ceramic tube.
An airtight joint structure between a ceramic tube and a metal, wherein the other end portions of the members are configured to be in contact with each other.