JPH06260121A - Vacuum container using beryllium foil for window - Google Patents

Abstract

PURPOSE:To provide a vacuum container which uses a beryllium foil for the window and whose window is prevented from being cracked or damaged beforehand to improve air-tightness of the window and provide manufacturing method of the container. CONSTITUTION:A vacuum container 1 using a beryllium foil for the window is a container having a window 2 made of a beryllium foil with thickness from 10 to 100mum by diffusion joining or soldering of the foil to an open part 1a. The micro Vicker's hardness of the beryllium foil is set to be 150-300 and the shear stress of the beryllium foil is set to be >=3.0g/mum/mm<2> for unit thickness of the beryllium foil (mum) in the case the thickness is <70mum and >=2.5g/mum/mm<2> in the case the thickness is >=70mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses beryllium foil for a window suitable for use in, for example, an X-ray tube, an X-ray fluorescence multiplier tube, an X-ray proportional counter tube, an X-ray lithography, an X-ray detection tube and the like. It was about the vacuum container.

[0002]

2. Description of the Related Art Generally, in an X-ray tube, an X-ray fluorescence multiplier tube, an X-ray proportional counter tube, an X-ray lithography, an X-ray detection tube, etc., as shown in FIGS. 11
A window 12 made of beryllium foil is airtightly joined to a via a protective ring 13, and is used as an input window or an output window. In addition, 14 and 15 in the figure are brazing filler metals. in this case,
Since the beryllium foil and the dissimilar metals are exposed to a temperature atmosphere of 350 to 500 ° C. in the exhaust step during manufacturing, the joining of the beryllium foil and the dissimilar metal is performed by raising the temperature to a high temperature by a diffusion joining method or a brazing method.

By the way, the beryllium foil used for the window 12 of the conventional X-ray tube is obtained by hot rolling an ingot, or vapor-depositing the ingot to a certain thickness and then hot rolling it. It was finished in thickness. However, beryllium has a poor rolling property as compared with copper, aluminum, and the like, and has a large variation in physical characteristics, and it is difficult to reduce the variation range. When a beryllium foil having a large variation in physical properties was used, cracks 16 were formed in the window 12 as shown in FIG. Furthermore, when exhausting air in the manufacturing process of the X-ray tube, a pressure difference of 1 atm is applied to the window 12, so that the window 12 is damaged on the vacuum side 17 as shown in FIG.
There was a phenomenon that caused it.

[0004]

When the beryllium foil becomes extremely thin, particularly when it has a thickness of 100 μm or less, the absolute total strength of the beryllium foil is the same as that of the beryllium foil even if the strength per unit area and unit thickness of the beryllium foil is the same. It decreases with the decrease in depth.

However, the beryllium foil used as the window 12 of the X-ray tube must be vacuum-tight regardless of its thickness, and must be vacuum-tight. Cracks 16 and breaks 17 should not occur with respect to the thermal stress in the evacuation process and the differential pressure of 1 atm generated by keeping the inside of the tube in a vacuum atmosphere. However, conventionally, when a beryllium foil having a thickness of 100 μm or less is joined by a diffusion joining method or a brazing method, the above-mentioned phenomenon often occurs,
Beryllium foil with stable quality could not be obtained.

The cause of these occurrences is that when the beryllium foil and the metal to be joined to the beryllium foil are joined at the time of joining, the beryllium foil is cracked by the tensile, compressive or bending stress applied to the beryllium foil. , By further maintaining the vacuum atmosphere, a shear pressure is generated at the boundary surface of the joint due to the pressure difference of 1 atm,
It cannot withstand this stress and the beryllium foil is damaged.

Regarding the physical characteristics of the beryllium foil used at this time, the hardness and the maximum shear load when the beryllium foil was broken by pressing a round bar on the beryllium foil were measured. As a result, the micro Vickers hardness was 320 to 340. , The shear stress is 2.
3 g / μm / mm ² Met. And, the shape of the beryllium foil after the shear stress measurement was fractured because plastic deformation was not observed so much. In order to reduce the hardness, the beryllium foil is annealed in a vacuum to have a hardness of 140 and a shear stress of 3.2 g / μ.
m / mm ² Beryllium foil was used to bond it to iron by diffusion bonding in vacuum, but the beryllium foil was destroyed during evacuation.

That is, in the former case, the beryllium foil has a large pressure strain due to rolling, and therefore has a large number of internal defects such as dislocations. Although the hardness increases, on the contrary, the deformability decreases and the internal defects start. The shear stress is reduced. In the latter case, the beryllium foil is secondarily recrystallized by annealing and the brittle transition temperature rises, so that the hardness,
Shear stress is reduced.

The present invention solves the above inconveniences, and provides a vacuum container using a beryllium foil for a window in which cracks and breakage are prevented from occurring and the airtightness of the window is remarkably improved. The purpose is to

[0010]

The present invention relates to a vacuum container using a beryllium foil for a window in which a window made of beryllium foil having a thickness in the range of 10 to 100 μm is diffusion-bonded or brazed to an opening. The micro Vickers hardness of the beryllium foil is set in the range of 150 to 300, and the shear stress of the beryllium foil is equivalent to the unit thickness (μm) of the beryllium foil (1) 3.0 g / in the beryllium foil of less than 70 μm. μm / mm ² Above, (2) 2.5g / μm / mm ² for beryllium foil with a thickness of 70μm or more The above is a vacuum container using beryllium foil for the window set as described above.

[0011]

According to the present invention, cracks and breakage of the window are prevented from occurring at the time of joining and exhausting, and the airtightness of the window is remarkably improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

The vacuum container using beryllium foil for the window according to the present invention is constructed as shown in FIGS. 1 and 2, and the opening 1a of the vacuum container 1 is made of beryllium foil having a thickness of 10 to 100 μm. The window 2 is hermetically joined via the protective ring 3 and is used as an input window or an output window. Reference numerals 4 and 5 in the drawing are brazing materials.

In this case, the diffusion bonding method or the brazing method is used for the airtight bonding, but the micro Vickers hardness of the beryllium foil is set in the range of 150 to 300, and the shear stress of the beryllium foil is the same as that of the beryllium foil. Equivalent to unit thickness (μm) (1) 3.0 g / μm / mm ² for beryllium foil with a thickness of less than 70 μm Above, (2) 2.5g / μm / mm ² for beryllium foil with a thickness of 70μm or more Above, it is set to. Next, both the diffusion bonding method and the brazing method will be specifically described in terms of manufacturing methods. (In case of diffusion bonding method)

As shown, the opening 1a of the vacuum container 1
Further, a window 2 made of beryllium foil having a diameter of 18 mm and a thickness of 60 μm is airtightly joined via a protective ring 3 and brazing materials 4 and 5. In this case, a beryllium foil having a thickness of 60 μm was annealed in vacuum at 800 ° C. for 20 minutes and taken out. This beryllium foil was measured with a micro Vickers hardness meter under a load of 200 g and a holding time of 30 seconds. The shear stress was 5 m in diameter when the beryllium foil was fixed with a circular ring made of rubber and then stretched and fixed in the compression load cell of the compression tester.
A stainless steel round bar of m was continuously pressed against the beryllium foil at a speed of 1 mm / sec, and the load applied to the round bar at this time was written on the recording paper.

The beryllium foil thus measured has a hardness of 220 and a shear stress of 4.5 g / μm / mm ^2. Met. Diffusion bonding is performed in a vacuum at a bonding temperature of 600
Hold time 30 minutes, applied pressure 2.5 Kg / mm ² The brazing material is silver brazing (Ag 61%, Cu 24%, In 15%), and the vacuum container 1 and the protection ring 3 are made of stainless steel 304.
Was used.

The window 2 thus obtained had a slight concave surface on the vacuum side of the beryllium foil, but no cracks were observed, and there was no damage even with a pressure difference of 1 atm during evacuation, and vacuum tightness was obtained. Was also good.

The vacuum vessel 1 and the protection ring 3 are made of nickel-plated iron. Under the above conditions, only the pressure is 3.5 Kg / mm ^2. However, the beryllium foil showed almost no deformation and the vacuum airtightness was good. (In case of brazing method)

As shown, the opening 1a of the vacuum container 1
The window 2 made of beryllium foil having a diameter of 18 mm and a thickness of 89 μm is airtightly bonded to the base 2 through the protective ring 3 and the brazing material 5. In this case, the brazing material 4 should be omitted. Then, a beryllium foil having a thickness of 89 μm was annealed in vacuum at 750 ° C. for 20 minutes and taken out. The hardness and the shear stress of this beryllium foil were measured in the same manner as in the above diffusion bonding method, and they were 225 and 5.0 g / μm / mm ² , respectively.
Met. Using this beryllium foil, a temperature rising rate of 25 ° C., a temperature of 770 ° C., a holding time of 5 minutes were performed in vacuum, and the brazing material was brazed using silver brazing as in the diffusion bonding method. The vacuum container 1 and the protection ring 3 are made of stainless steel 3
04 was used without nickel plating.

In the thus-obtained window 2, beryllium foil was found to have some concave deformation on the vacuum side, but no cracks were found, and no damage was found even with a differential pressure of 1 atm during exhaust. The vacuum tightness was also good.

[0021]

According to the present invention, the cracking of the ultra-thin beryllium foil at the time of joining and the breakage of the airtightness due to the breakage of the ultra-thin beryllium foil at the time of evacuation are not affected by the diffusion bonding method or the brazing method. Can be prevented. As a result, the reliability of the joint is improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a vacuum container using beryllium foil for a window according to an embodiment of the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a cross-sectional view showing a conventional vacuum container using beryllium foil for a window.

FIG. 4 is a plan view of FIG.

FIG. 5 is a plan view showing a defect of a conventional vacuum container using beryllium foil for a window.

FIG. 6 is a plan view showing another defect of the conventional vacuum container using beryllium foil for the window.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Vacuum container, 1a ... Opening part of vacuum container, 2 ... Window, 3 ...
Protective ring, 4,5 ... brazing material.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H01J 47/06 4230-5E

Claims (1)

[Claims] 1. A vacuum container using a beryllium foil for a window, wherein a window made of beryllium foil having a thickness in the range of 10 to 100 μm is diffusion-bonded or brazed to an opening. The hardness is set in the range of 150 to 300, and the shear stress of the beryllium foil is equivalent to the unit thickness (μm) of the beryllium foil. (1) 3.0 g / μm /
mm ² Above, (2) 2.5g / μm / for beryllium foil of 70μm or more
mm ² Above, the vacuum container using beryllium foil for the window, characterized in that