JPH11213880A - Manufacture of x-ray tube target, and target manufacturing unit thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture an X-ray tube target provided with high durability and difficult to be peeled by bonding a target member of the tungsten material having sufficient thickness to a peripheral surface of a base. SOLUTION: An insert material having a melting point lower than that of a target member 3 and a base 2 is interposed between the inner peripheral surface of the target member 3 of the tungsten material and the base 2. In a vacuum atmosphere, the target member 3 is fitted on the base 2, and the target member 3 is sealed by the base 2 and a cover member 4 so as to form a target manufacturing unit formed by combining the base 2, the target member 3, the insert material and the cover member 4 (unit forming process). This target manufacturing unit is heated at the predetermined temperature, while pressurizing the unit so as to manufacture an X-ray tube target.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for manufacturing an X-ray tube target that generates X-rays in response to collision of electrons emitted from an electron gun, and more particularly to an X-ray tube using a tungsten material as a target member. Target manufacturing method,
The present invention relates to a target manufacturing unit manufactured in an intermediate step of the manufacturing method.

[0002]

2. Description of the Related Art As is well known, an X-ray tube used for an X-ray source of various X-ray utilizing apparatuses such as an X-ray diffractometer is known.
An X-ray tube target (anti-cathode) is arranged opposite to the electron gun, and electrons emitted from the electron gun collide with the surface of the X-ray tube target to generate X-rays from the surface of the X-ray tube target. It has a structure to make it.

As materials for generating X-rays in response to electron collision, for example, molybdenum, chromium, tungsten,
Metal materials such as gold and silver can be used. When the entire X-ray tube target is formed of such a metal material, not only is the product cost high, but also the thermal conductivity is low depending on the material, and the heat generated when electrons collide is efficiently cooled. There is a problem that cooling water cannot be kept in contact with cooling water for a long time due to low corrosion resistance.

Accordingly, a conventional X-ray tube target is shown in FIG.
As shown in FIG. 3, a target material 20 is formed of a metal material that emits X-rays in response to the collision of electrons, and the target material 20 is formed of a metal material having a good thermal conductivity.
1, and cooling water is circulated on the back side of the base 21 via pipes 22 and 23 to cool the heat generated at the time of electron collision.

[0005]

A conventional X-ray tube target of this kind includes a target material 20 on a required portion of a base 21.
In this method, bonding or forming is performed by brazing, vacuum deposition, ion plating, sputtering, plating, or the like. However, any of these methods has a problem that the target material 20 is easily peeled from the base 21.

In particular, in the case of the target material 20 using a tungsten material, it is limited that the target material 20 is formed on the base 21 to a thickness of about 20 μm by ion plating. Since re-polishing cannot be performed even if the surface frequently occurs and the surface becomes rough due to use, there is a disadvantage that durability is poor.

The present invention has been made in view of such circumstances, and has a high durability which is hard to peel off by joining a target member made of a tungsten material having a sufficient thickness to a peripheral surface of a base. It is intended to manufacture an X-ray tube target.

The present applicant has previously proposed a method of manufacturing an X-ray tube target in which a target member 20 is joined to the surface of a base 21 by utilizing liquid phase diffusion by an insert material (Japanese Patent Application Laid-Open No. 9-161673). Reference). The present invention is an improvement of the previously proposed manufacturing method, in particular, an X-ray tube target using a tungsten material as a target member.
It can be manufactured with good yield.

[0009]

In order to achieve the above object, a method of manufacturing an X-ray tube target according to the present invention is characterized by including the following steps. A target member forming step of forming an annular target member using a tungsten material A base forming step of forming a base having a cylindrical peripheral wall for externally fitting the target member by using a metal material having good heat conductivity. Using a metal material having good conductivity, a cover member forming step of forming a cover member having a cylindrical peripheral wall that covers the periphery of the target member. At least an inner peripheral surface of the target member and the base, the target member, While interposing an insert material having a melting point lower than that of the base, under a vacuum atmosphere, the target member is externally fitted to the base, and a cover member is attached around the target member. The target member is sealed by using the base, target member, insert material and cover member. A heating step of heating the target manufacturing unit to a predetermined temperature while uniformly pressing the target from the surroundings and melting the insert material; isothermally solidifying the insert material while uniformly pressing the target manufacturing unit from the surroundings. Isothermal solidification process After the isothermal solidification process, a diffusion heat treatment process in which the base, the target member, and the insert material are mutually diffused by heat treatment while uniformly pressing the target manufacturing unit from the surroundings.

According to the present invention, in the heating step, the base melts at a low eutectic temperature due to the eutectic with the insert material, so that the so-called liquid phase diffusion proceeds efficiently, and the target member and the base are added. Join under pressure.

Subsequently, by isothermally solidifying the insert material, the joined portion does not melt even if the insert material is reheated to the joining temperature thereafter. Therefore, even if the temperature becomes high due to the collision of electrons, there is no possibility that the target member is detached from the base. Here, “isothermal solidification” refers to a phenomenon in which the composition of a metal material changes due to diffusion while the temperature is maintained at a constant temperature, and the melting point increases to solidify the metal material.

Furthermore, in the diffusion heat treatment step, since the material of the joining portion is homogenized, the adhesion between the base and the target member is large, and a more reliable joining state can be formed.

[0013] The tungsten material forming the target member is very brittle. Therefore, the heating step,
In the isothermal solidification step and the diffusion heat treatment step, if non-uniform pressure acts on the outer peripheral surface and the inner peripheral surface of the target member, cracks occur and cause a reduction in yield.

In the method of manufacturing an X-ray tube target previously proposed by the present applicant (see Japanese Patent Application Laid-Open No. 9-161673), the outer periphery of the target member is surrounded by a frame material. In particular, when the target member is formed of a tungsten material, the member tends to crack.

Therefore, in the present invention, a target manufacturing unit having a structure in which a target member is fitted on a base and a cover member is mounted around the target member, and the target member is sealed by the base and the cover member. Is formed in advance. By subjecting this target production unit to the above heating step, isothermal solidification step, and diffusion heat treatment step, a uniform pressure acts on the inner peripheral surface of the target member via the base, and the outer peripheral surface of the member also Since a uniform pressure acts through the cover member, cracking of the target member can be suppressed.

Further, if the cover member is formed of the same material as the base and the peripheral walls of the base and the cover member are formed in a cylindrical shape having substantially the same thickness, the pressure acting on the inner peripheral surface of the target member can be improved. And the pressure acting on the outer peripheral surface can be made substantially uniform, so that cracking of the target member can be further suppressed.

It has been difficult with conventional techniques to form a hard and brittle tungsten material in an annular shape. However, the present inventors have developed a seamless circle by drawing while heating the tungsten material. The formation of an annular target member was realized.

Further, in the unit forming step, the target member is sealed with the base and the cover member in a vacuum atmosphere, so that a sealed chamber surrounded by the base and the cover member is evacuated to a vacuum state. It becomes possible to appropriately advance liquid layer diffusion and the like. here,
Sealing between the base and the cover member under a vacuum atmosphere can be realized by electron beam welding. Preferably, the insert material is formed of a material that is eutectic with the metal material forming the base in the heating step.

The target manufacturing unit formed in the intermediate step of the above-described method for manufacturing an X-ray tube target includes a base having a cylindrical peripheral wall formed of a metal material having good heat conductivity, and a base material formed of a tungsten material. And a cover member having a cylindrical peripheral wall which is formed of a metal material having good heat conductivity and covers the periphery of the target member.
Then, an insert material having a melting point lower than that of the target member and the base is interposed between at least the inner peripheral surface of the target member and the base, and the target member is formed by sealing with the base and the cover member. Is done.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a longitudinal sectional view of an X-ray tube target manufactured by a manufacturing method according to an embodiment of the present invention. This X-ray tube target 1
This is a rotary target (anti-cathode) called a rotor target, and has a structure in which an annular target member 3 is joined to the circumferential surface of a base 2 having a bottomed cylindrical shape. The base 2 is formed of a metal material having good heat conductivity, for example, a copper alloy such as oxygen-free copper or chromium copper, and is mounted on a rotation driving device (not shown) and rotates at high speed.

The target member 3 is formed of a tungsten material. Since the inner peripheral surface of the target member 3 is in contact with the base 2, the thermal conductivity is good, and the cooling efficiency of the target member 3 is high.

That is, X-rays are generated from the surface of the target member 3 by colliding electrons emitted from an electron gun (not shown) with the target member 3. At this time, the target member 3 generates high heat due to the collision of the electrons. Occur. In order to cool this heat, cooling water is circulated to the back side of the base 2 through the pipes 5a and 5b during operation, and heat exchange between the target member 3 and the cooling water through the base 2 It is carried out. Therefore, by bringing the target member 3 into contact with the base 2 that mediates the heat exchange, the cooling efficiency can be improved.

Both side edges of the target member 3 are sandwiched between a step 2a of the base 2 and a step 4a of the cover member 4 described later to prevent the target member 3 from slipping off.

Next, a method of manufacturing the above-mentioned X-ray tube target will be described in detail mainly with reference to FIGS. First, an annular target member 3 is formed using a tungsten material (target member forming step). In this step, a seamless annular target member 3 can be obtained by drawing while heating the tungsten material. Here, if the tungsten material is too thick, peeling occurs in the drawing process, while if it is too thin, cracks occur. Therefore, adjusting the thickness of the material is an important condition in this step. According to the experiments performed by the present inventors, the target member is set to have a thickness of 0.05 mm to 1.0 mm.
Thus, a desired X-ray tube target could be manufactured. It is needless to say that the tungsten material prepared in this step must be thicker than the target member 3 of the X-ray tube target 1 (final product) shown in FIG.

Further, the base 2 is formed using the above-mentioned metal material having good heat conductivity, and the cover member 4 is formed from the same metal material as the base 2. Member forming step). The base 2 is formed in a cylindrical shape with a bottom, and a step 2a is formed on the outer periphery. Cover member 4
Is formed in a cylindrical shape, and a step portion 4a is formed on the inner periphery.

The thickness of the peripheral wall 2b (formed in a cylindrical shape) on the base 2 on which the target member 3 is fitted as described later, and the peripheral wall covering the outer periphery of the target member 3 on the cover member 4 as described later. The thickness of 4b is set to substantially the same thickness. In addition, the step 2 a of the base 2 and the step 4 a of the cover member 4 are set to a height substantially equal to the thickness of the target member 3.

Next, the target member 3 is externally fitted to the peripheral wall 2b of the base 2, and the cover member 4 is externally fitted to the outer periphery of the base 2 and the target member 3, so that the target member 3
Is covered with the base 2 and the cover member 4 (see FIG. 2).

At this time, an insert material is interposed at least between the base 2 and the target member 3. As the insert material, various metal materials having a lower melting point than the base 2 and the target member 3 can be used. Preferably, a melting point lowering element is added to a metal material having a composition similar to that of the base 2 and the target member 3. Or a metal material that forms a liquid phase by eutectic with the base 2 and the target member 3. Examples of this type of insert material include gold,
Silver, a titanium alloy, tin, or the like can be applied.

The insert material is applied between the base 2 and the target member 3 in the form of a paste, or is inserted between the base 2 and the target member 3 in the form of a thin plate. Alternatively, the bonding surface of the base 2 or the target member 3 may be plated or vapor-deposited in advance.

According to the experiments by the present inventors, silver was used as an insert material, and the entire surface of the target member 3 was plated so that the space between the base 2, the target member 3, and the cover member 4 was firmly fixed to each other. We could join.

Subsequently, the base 2, the target member 3,
The combination of the cover members 4 is placed in a separately provided vacuum suction chamber and vacuum suction is performed. As a result, a vacuum atmosphere is formed, and a portion surrounded by the base 2 and the cover member 4 (a portion where the target member 3 is fitted) is sufficiently evacuated. If the gas remains in this portion, it is not possible to properly perform a process by a HIP (Hot Uniform Hot Pressing Device) described later. Then, under the vacuum atmosphere, the base 2 and the cover member 4
2 (a and b in FIG. 2) are subjected to electron beam welding, and the target member 3 is sealed with the base 2 and the cover member 4. Through the above steps (unit forming step), the target manufacturing unit 6 is formed.

Next, this target manufacturing unit 6 is
It is inserted and arranged in the pressurizing chamber of the pressurizing device. As the pressurizing device, a hot press having a heating means inside is used. If a hot press device generally called a HIP (Hot Uniform Hot Pressing Device) is used, the pressure required for liquid phase diffusion can be applied from around the target manufacturing unit 6 and the following steps can be performed. Since the processing can be performed continuously in the pressurizing chamber 12, it is possible to proceed with the operation quickly.

FIG. 3 is a diagram schematically showing the configuration of the HIP 10. As shown in FIG. A heater 13 as a heating means is installed in the pressurizing chamber 12, and the inside of the pressurizing chamber 12 can be maintained at a desired constant temperature by computer control.
Impurity gas in the pressurized chamber 12 can be removed by suction through an exhaust pipe 14, while filling the pressurized chamber 12 with an inert gas such as N ₂ gas through a gas supply pipe 15. Is available.

With the target manufacturing unit 5 placed on the mounting table 11 in the pressurizing chamber 12, first, a heating step of melting the insert material is performed. In this step, the target production unit 6 is evenly pressurized from the surroundings and heated to a predetermined temperature. The temperature at this time is
And a temperature lower than the melting point of the target member 3, but set to an appropriate temperature at which the insert material melts to form a liquid phase. The pressure is set to an appropriate pressure that does not cause deformation or breakage of the base 2 or the like in consideration of expansion of the base 2 or the like due to heating and materials of the base 2 and the target member 3. That is, if the pressure is too low, the thin target member 3 may be cracked due to expansion of the base 2 due to heating. On the other hand, if the pressure is too large, the base 2 and the like may be deformed by the pressure.

This heating step is continued for an appropriate time required until the insert material is changed to a liquid phase, and after the insert material is eutectic to form a liquid phase, the process proceeds to the next step of isothermal solidification. In the isothermal solidification process, the pressurizing chamber 1
The temperature and pressure in 2 are kept for an appropriate time while being set to values substantially the same as or similar to those in the heating step. By this isothermal solidification process, liquid phase diffusion between the insert material, the base 2 and the target member 3 is advanced. Due to the liquid phase diffusion in the isothermal solidification step, the composition at the joint between the base 2 and the target member 3 changes, and the melting point of the insert material rises to solidify. As a result, it is possible to form a state in which the base 2 and the target member 3 are firmly joined, and the joined portion is not melted even when reheated to the joining temperature.

In the isothermal solidification step, while the interface between the solid phase and the liquid phase is moving, the elements constituting the insert material, the base 2 and the target member 3 are mutually diffused.
Isothermal coagulation is completed in a relatively short time compared to the time when the components of these components are homogenized. Therefore, the state where the heated and pressurized state in the pressurizing chamber 12 is maintained is continued to homogenize the composition at the joint between the base 2 and the target member 3 (diffusion heat treatment step).

After the insert material is isothermally solidified by this diffusion heat treatment step, diffusion proceeds between the insert material, the base 2 and the target member 3, and the base 2 and the target member 3 are more firmly joined. You. This diffusion heat treatment step is performed over a sufficiently long time as compared with the isothermal solidification step.

In the course of performing the heating step, the isothermal solidification step, and the diffusion heat treatment step as described above, solid phase diffusion also proceeds between the base 2 and the cover member 4 made of substantially the same metal material, A strong joining state is also formed between the base 2 and the cover member. In this state, the target member 3
It is buried inside the base 2 and the cover member 4. Therefore, the outer peripheral surface of the cover member 4 is mainly ground to expose the target member 3 to the surface. Finally, the base 2 is processed into an appropriate shape and dimensions, and the X-ray tube target 1
Is formed (see FIG. 1).

According to the experiments performed by the present inventors, an X-ray tube target having a target member having a thickness of about 0.2 mm could be manufactured by the above manufacturing method. Further, when the thickness of the target member exceeds 0.7 mm, the thermal conductivity deteriorates, while when the thickness is 0.05 mm or less, cracks easily occur.

The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the method of manufacturing the so-called rotor target has been described in detail. However, the present invention relates to an X-ray tube target other than the rotor target, for example, an X-ray tube target (fixed cathode) called a fixed target. Of course, it can also be applied to the manufacture of

In the above embodiment, an insert having a lower melting point than the base 2 and the cover member 4 can be interposed between the base 2 and the cover member 4. By doing so, the base 2, the insert material,
Also, the liquid phase diffusion proceeds between the cover member 4 and the base 2 and the cover member 4 can be more firmly joined. Furthermore, the insert material can be interposed not only on the inner peripheral surface of the target member 3 but also between the side surface of the target member 3 and the side surfaces of the step 2 c of the base 2 and the annular member 4. By doing so, the bonding area by liquid phase diffusion bonding is increased, and a stronger bonding state can be formed.

[0042]

As described above, according to the present invention,
Even when the base and the target member are each formed of a metal material having a large temperature difference in melting point, it is possible to improve the durability by reliably joining the members by the action of the insert material, and in particular, An X-ray tube target using a tungsten material as a target member can be manufactured with high yield.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an X-ray tube target manufactured by a manufacturing method according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a target manufacturing unit according to the embodiment of the present invention.

3 is a cross-sectional view showing a state where the target manufacturing unit shown in FIG. 2 is arranged in a pressurizing chamber of a pressurizing device.

FIG. 4 is a cross-sectional view for explaining a conventional general X-ray tube target.

[Explanation of symbols]

 1: X-ray tube target 2: Base 3: Target member 4: Cover member 6: Target production unit 10: HIP 12: Pressurizing chamber 13: Heater

Claims (6)

[Claims] 1. A target member forming step of forming an annular target member using a tungsten material, and a base having a cylindrical peripheral wall for externally fitting the target member using a metal material having good heat conductivity. A cover member forming step of forming a cover member having a cylindrical peripheral wall covering the periphery of the target member using a metal material having good heat conductivity; An insert material having a lower melting point than the target member and the base is interposed between the peripheral surface and the base, and the target member is externally fitted to the base under a vacuum atmosphere, and the target The cover member is mounted around a member, and the target member is sealed by the base and the cover member. Material, a unit forming step of forming a target manufacturing unit combining the insert material and the cover member, and a heating step of heating the target manufacturing unit to a predetermined temperature while uniformly pressing the surroundings, and melting the insert material, An isothermal solidification step of isothermally solidifying the insert material while uniformly pressing the target production unit from the surroundings, and after the isothermal solidification step, further heat-treating the target production unit while uniformly pressurizing the surroundings, A diffusion heat treatment step of mutually diffusing the base, the target member, and the insert material. 2. The X-ray tube target according to claim 1, wherein in the target member forming step, a seamless annular target member is formed by drawing while heating a tungsten material. Production method. 3. The cover member is formed of the same material as that of the base, and each peripheral wall of the base and the cover member is formed in a cylindrical shape having substantially the same thickness. 3. The method for manufacturing an X-ray tube target according to 2. 4. The unit according to claim 1, wherein in the unit forming step, the target member is sealed by electron beam welding between the base and the cover member. A method for manufacturing the X-ray tube target according to the above. 5. A base formed of a metal material having good heat conductivity and having a cylindrical peripheral wall, and a target member formed in an annular shape of a tungsten material and fitted to the peripheral wall of the base. And a cover member formed of a metal material having good heat conductivity and having a cylindrical peripheral wall covering the periphery of the target member, between at least an inner peripheral surface of the target member and the base. A target manufacturing unit, wherein an insert material having a lower melting point than the target member and the base is interposed, and the target member is sealed by the base and the cover member. 6. The target member has a thickness of 0.05 m.
The target production unit according to claim 5, wherein the target production unit is formed to have a length of m to 1.0 mm.