JPH05283022A - Anode for x-ray tube - Google Patents

Abstract

PURPOSE:To realize high power and a long life with the generation of surface roughness under use environment prevented, by composing an anode, of Re-W alloy which includes substantial isometic organization and a relative density of a specific % or more, and in which Re has a specific wt.% and the remainder is composed of W or doped W. CONSTITUTION:Re powder of 1g., having a mean grain diameter of 5mum, and W powder of 9g., having a mean grain diameter of 3mum are mixed with acetone used as a binder, and a mixture is press-formed in a normal condition and is sintered under an Ar atmosphere. This sintering is made at 2200 deg.C for 6-13 hours, and a sintered body of Re-W alloy, having a relative density of 92-96%, is obtained. Static hydrostatic pressure forming treatment is made to this sintered body under the condition of 1700-2000 deg.C and 2000kg/cm<2> to obtain Re-W alloy, which is having actual isometric organization and a relative density of 96 % or more and Re of 3-15wt.% and in which the remainder is composed of W or doped W. An anode 3 is formed of this alloy, and is faced to a cathode 1 to be applied by high pressure, obtaining an X-ray 6. Consequently, high power and a long life can be realized with generation of surface roughness under use environment prevented.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an anode for an X-ray tube,
X which is particularly suitable as an anode target for a fixed anode X-ray tube
The present invention relates to an anode for a wire tube.

[0002]

2. Description of the Related Art An X-ray tube, for example, a fixed anode type X-ray tube, has a structure as shown in FIG. 1, in which a cathode 1 and an anode 3 supported by a support 2 are placed in a high vacuum tube. Are installed opposite to each other, and a cathode and an anode are connected to a high-voltage power supply (not shown). Cooling water 4 is circulated in the support 2 to cool the anode 3. When a high voltage is applied between both electrodes, the thermoelectron beam 5 generated from the cathode collides with the anode 3 and, at this time, X-rays are generated in the direction of arrow 6. As an anode target material for such a fixed anode type X-ray tube, a W alloy in which a small amount of W or Fe is doped to raise the recrystallization temperature is conventionally used as the material. These materials were manufactured by powder metallurgy molding, sintering, and rolling into plate materials. Conventionally, it has been considered that in order to obtain high-temperature strength, it is necessary to make a true density and to form a fibrous structure (texture), and it is essential to roll a W or W alloy sintered body into a plate material. It was supposed to be a process. The anode for an X-ray tube manufactured in this manner is liable to undergo rapid deterioration of its characteristics due to surface roughness in a harsh environment of use. This is likely to occur, and thus there was a limit to increasing the output.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems associated with the above-mentioned prior art, and prevents the occurrence of surface roughness in the environment of use, and further An object of the present invention is to provide an anode for an X-ray tube, which can achieve higher output and longer life.

[0004]

In order to solve the above problems, the anode for an X-ray tube of the present invention comprises a Re-W alloy having a substantially equiaxed crystal structure and a relative density of 96% or more. It is characterized by becoming. The Re-W alloy is Re
It is preferable that the balance is 3 to 15% by weight, and the balance is W or doped W.

Detailed Description of the Invention The anode for the X-ray tube of the present invention uses a Re-W alloy as its material. By using Re as an alloy component instead of conventional W or doped W, the strength at high temperature can be increased. The content of Re is 3 to 15% by weight
Is preferable, and more preferably 3 to 10% by weight. If the Re content is less than 3% by weight, the effect of increasing the high temperature strength cannot be obtained by adding Re, while if it exceeds 15% by weight, Re is a very expensive metal, which is disadvantageous in terms of cost. In addition to the effect of addition reaching saturation, formation of an intermetallic compound with W becomes brittle, which is not preferable. Further, W is preferable as the base metal of the alloy.

In the present invention, the metal structure of the Re-W alloy has a substantially equiaxed crystal structure. With the equiaxed crystal structure as described above, even if a crack is generated due to thermal shock, the crack stops in a shallow state of the surface and it is difficult to proceed to the inside, and the reliability is improved as compared with the conventional texture. Further, the heat load is made uniform, and the generation state of X-rays can be stabilized. Here, having a substantially equiaxed crystal structure means that distributions of peak intensities in X-ray diffraction are substantially the same in the X, Y, and Z axis directions.

In the present invention, the relative density of the Re-W alloy is 96% or more, preferably 97% or more. If the relative density is less than 96%, sufficient thermal shock resistance cannot be obtained, surface roughness is severe, stress cracking occurs, and sufficient reliability cannot be obtained.

Manufacturing Method The manufacturing method of the X-ray tube anode of the present invention will be described below.

In order to produce a Re-W alloy having a substantially equiaxed crystal structure and a relative density of 96% or more, after sintering the Re-W alloy by a usual powder metallurgy method, HIP is used.
It can be manufactured only by performing (hot isostatic pressing) treatment. More specifically, first, a predetermined amount of Re powder (average particle size of 0.1 to 1) is adjusted so as to obtain a desired Re content.
0 μm, preferably 0.5 to 5 μm, more preferably 1 to 2 μm) and W powder (average particle size 0.1 to 10 μm, preferably 1 to 5 μm, more preferably 2.5 to 3.5).
(μm) with an appropriate binder (acetone, etc.) and press-molded under normal conditions to obtain a molded body,
This molded body was subjected to 2000 to 22 under a vacuum inert gas atmosphere.
Sinter at 00 ° C. for about 6 to 8 hours. Thus, a Re-W alloy sintered body having a relative density of about 92 to 96% is obtained. This sintered body is 1700 to 2000 ° C., 1700 to 2
By performing the HIP treatment under the condition of 000 kgf / cm ² , a Re-W alloy having a relative density of 96% or more can be obtained. By properly selecting the temperature condition of this HIP treatment, a Re-W alloy having a desired relative density can be obtained. In addition, since this HIP treatment is isotropic pressure pressurization, a substantially equiaxed crystal structure is obtained.

According to this method, the sintered body of the Re-W alloy only has to be HIP-treated, and the conventional rolling process for obtaining a true density and forming a fibrous structure is completely unnecessary. In addition, the process has a great merit, and the cost can be reduced.

[0011]

The following examples serve to explain the present invention more specifically. The scope of the present invention is not limited by the following examples.

Example 1 1 g of Re powder (average particle size 5 μm) and W powder (average particle size 3)
9 μm) was mixed with acetone as a binder, and the mixture was press-molded under normal conditions to obtain a molded body. The molded body was placed in an Ar atmosphere at 2200 ° C. for 6 hours or
Sintered for hours. Thus, a sintered body of a 10% Re-W alloy having a relative density of 92 to 96% was obtained. This sintered body 17
The relative density is 97 to 100% by HIP treatment under the conditions of 00 to 2000 ° C. and 2000 kgf / cm ^2.
Re-W alloy of FIG. 2 shows the relationship between the temperature condition of the HIP treatment and the relative density of the obtained Re-W alloy. HI
When the P treatment temperature is 1700 ° C., the relative density is approximately 97 to 99.
%, The relative density is approximately 98 when the HIP processing temperature is 1800 ° C.
The relative density was about 100% when the HIP treatment temperature was 2000 ° C.

When the Re-W alloy thus obtained was used as an anode of a fixed anode type X-ray tube, good characteristics were obtained without surface roughness.

When the HIP treatment temperature was 1600 ° C., the relative density was about 94 to 98%, and both good and bad ones were obtained.

Comparative Example 1 10% Re-W was molded and sintered by a conventional powder metallurgy method, and this sintered body was rolled to produce a plate material. This plate was cut out to make an anode for a fixed anode type X-ray tube.
It could not be manufactured industrially due to cracking due to rolling.

Comparative Example 2 1 g of Re powder (average particle size 5 μm) and W powder (average particle size 3)
9 μm) was mixed with acetone as a binder, and the mixture was press-molded under normal conditions to obtain a molded body. The molded body was placed in an Ar atmosphere at 2200 ° C. for 6 hours or
Sintered for hours. Thus, a sintered body of a 10% Re-W alloy having a relative density of 92 to 96% was obtained (see FIG. 2).

When the Re-W alloy thus obtained is used as an anode of a fixed rotating anode type X-ray tube, surface roughness occurs and stress cracking occurs, and its characteristics are equal to or lower than those of conventional ones. Met.

[0018]

According to the X-ray tube anode of the present invention, R having a substantially equiaxed crystal structure and a relative density of 96% or more.
By using the e-W alloy, it is possible to prevent the occurrence of surface roughness under the use environment and to further increase the output.
The life can be extended.

[Brief description of drawings]

FIG. 1 is an explanatory view of the outline of the structure of a fixed anode X-ray tube.

FIG. 2 is a graph showing the relationship between the HIP treatment temperature and the relative density of Re-W alloy.

[Explanation of symbols]

 3 anode

Claims (2)

[Claims] 1. An anode for an X-ray tube, which is made of a Re-W alloy having a substantially equiaxed crystal structure and a relative density of 96% or more. 2. The anode for an X-ray tube according to claim 1, wherein the Re-W alloy comprises Re 3 to 15% by weight and the balance W or doped W.