JP2013089377A - Target for x-ray tube and x-ray tube using the same, x-ray inspection device, and method of manufacturing target for x-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a target for X-ray tube which has high temperature strength and is reduced in cost, and a method of manufacturing the same.SOLUTION: The target for X-ray tube having a carbon base and an Mo base or Mo alloy base joined together through a joining layer is characterized in that when the joining layer has a composition ratio detected by EPMA, the joining layer has a diffusion phase of MoVX with 1-100 μm in thickness, a VX alloy layer of 10-500 μm in thickness, an X rich phase of 1-600 μm in thickness, an XZr alloy layer phase of 10-1,500 μm in thickness, where X includes at least one or more kinds selected from Nb, Ta, and W.

Description

The present invention relates to an X-ray tube target, an X-ray tube using the X-ray tube target, an X-ray inspection apparatus, and an X-ray tube target manufacturing method.

X-ray tube is an X-ray CT device, X-ray fluoroscopy device that uses X-ray transmission power to grasp the inside of a subject such as a human body, non-destructive inspection that detects defects inside a structure, case inside, etc. Analyzer (
For example, it is used for various X-ray inspection apparatuses such as luggage inspection apparatuses.
The X-ray inspection apparatus includes an X-ray detector that includes an X-ray tube that generates X-rays and a scintillator (including an image amplification tube) for detecting X-rays that have passed through the subject.
An X-ray tube generally includes a glass bulb, a pair of cathodes and an anode disposed so as to face each other in a metal or ceramic container, the cathode is composed of a tungsten filament or the like, and the anode is tungsten (W). , Molybdenum (Mo) or a target made of an alloy thereof. The operating principle of this X-ray tube is that electrons are emitted by heating the tungsten filament of the cathode, they are accelerated by the voltage applied between the anode and the cathode, and collide with the target that becomes the anode with kinetic energy as an electron beam. ,
As a result, X-rays are emitted from the target in a predetermined direction.
In recent years, X-ray CT, X-ray fluoroscopy devices, and nondestructive inspection devices are required to improve resolution by increasing the definition of X-ray images and to acquire moving images and shorten inspection times. In order to improve the resolution of X-ray CT, it is necessary to reduce the size of each X-ray scintillator used in the X-ray detection unit and arrange a large number of them in the same detection area. However, when the X-ray scintillator is reduced in size, the X-ray detection sensitivity for the same X-ray incident energy per unit area decreases. This reduction in sensitivity can be compensated for by increasing the X-ray output of the X-ray tube. Furthermore, moving image acquisition and inspection time can be shortened by increasing the X-ray output of the X-ray tube. For this reason, a high-power X-ray tube capable of generating stronger X-rays than before has been demanded, and its development and practical use have been performed.

In general, in order to increase the X-ray output of the X-ray tube, it is necessary to increase the kinetic energy of electrons colliding with the target. However, a part of the kinetic energy of electrons raises the temperature of the electron collision part on the target as thermal energy, causing the target itself to melt or the metal phase of the target to deteriorate due to the temperature rise.
For this reason, many high-power X-ray tubes have an axisymmetric rotating body (for example, a disk shape) as a target, and the focal plane of the target that receives electron beam irradiation by rotating at a high speed of 2000 rpm to 10,000 rpm or more with respect to the electron beam. It has a structure that constantly changes and prevents local temperature rise. An X-ray tube having such a target is called a rotating anode (target) X-ray tube.
In order to further increase the output of such a rotary anode X-ray tube, (1) the kinetic energy of the electron beam colliding with the target is increased after further increasing the rotation speed of the target to improve the cooling efficiency. (2) There are methods such as enlarging the target and widening the area where the electron beam collides.

X-ray CT or X-ray tube of X-ray inspection equipment is not continuous irradiation, but when one CT inspection and one nondestructive inspection are completed, the time during which X-ray irradiation is not performed before the next inspection (the energy input to the target) There is no time). Therefore, by increasing the heat capacity of the target as a whole, the maximum temperature of the target during X-ray irradiation can be suppressed and the average temperature of the target can be increased, thus supporting the high output of the X-ray tube. it can. Since the target becomes a rotating body when increasing the heat capacity of the entire target, it is desirable to reduce its mass as much as possible. As mentioned above, W, Mo and its alloys are required for the part of the target where the electron beam collides. However, the mass is too large to construct the target with only W, Mo and its alloys having high density and low specific heat. Not appropriate. Therefore, there is no problem in the mechanical strength at high temperature in order to suppress the large heat capacity and the weight increase of the target.
In addition, it is desirable to use it by joining with an alloy thereof.
Further, as a method for realizing an X-ray tube target of a high-power X-ray tube, a method of enlarging the heat radiation area by enlarging the target size of W, Mo or an alloy thereof can be considered. A significant increase in weight and size is required for the X-ray tube including the structure and bearings in consideration of the rigidity of the rotating body. Furthermore, when used in CT apparatuses where high-speed scanning is a trend, the entire X-ray tube of the CT apparatus needs to be rotated at the CT scanning speed, and thus it is very difficult to construct a structure that can withstand such a large centrifugal force.
As described above, an X-ray tube in which W, Mo and carbon are bonded can reduce the weight of the target. Japanese Patent No. 3040203 (Patent Document 1) has been proposed as such an X-ray tube target. Patent Document 1 uses a method of joining using V (vanadium) as a brazing material.

Japanese Patent No. 3040203

By using the method of patent document 1, the target for X-ray tubes excellent in the joining strength under high temperature is obtained. However, the brazing material using vanadium as disclosed in Patent Document 1 requires a manufacturing cost because vanadium is very expensive. In order to solve such problems, the present invention provides an X-ray tube target, a method for manufacturing the same, and an X-ray detector by increasing the bonding strength at high temperatures and using an inexpensive bonding method.

The X-ray tube target of the present invention is a target for an X-ray tube in which a carbon base material and a Mo base material or a Mo alloy base material are bonded via a bonding layer. When the composition ratio of the bonding layer is detected by EPMA, The bonding layer is a MoVX diffusion phase having a thickness of 1 to 100 μm and a thickness of 10 to 50.
0 μm VX alloy phase, 1 to 600 μm thick X-rich phase, 10 to 1500 μm thick XZ
An r alloy phase, wherein X is at least one selected from Nb, Ta, and W.
Further, the MoVX diffusion phase preferably includes a solid solution of MoVX. The VX alloy phase preferably has a Mo content of 10% by mass or less (including 0). Moreover, it is preferable that X is 90 mass% or more in the said X rich phase. The XZr alloy phase preferably includes a ZrC phase. Such X-ray tube targets are X-ray tubes,
Furthermore, it is most suitable for an X-ray inspection apparatus.

Moreover, the manufacturing method of the target for X-ray tubes of this invention WHEREIN: In the manufacturing method of the target for X-ray tubes which joined the carbon base material and Mo base material or Mo alloy base material through the joining layer, a carbon base material and M
o A first brazing filler metal layer made of V having a thickness of 0.001 mm or more and less than 0.01 mm, or Nb, Ta, or W having a thickness of 0.1 to 0.6 mm between the base material or the Mo alloy base material. At least one
Joining at a temperature of 1730 to 1900 ° C., a second brazing filler metal layer comprising a seed as a main component, a brazing filler metal layer producing step for producing a third brazing filler metal layer made of Zr having a thickness of 0.1 to 0.3 mm, and It comprises a joining process.
Moreover, it is preferable that a brazing material layer production process is a process of producing the clad material of a 1st brazing material layer, a 2nd brazing material layer, and a 3rd brazing material layer. Moreover, the brazing filler metal layer production process is performed on the second brazing filler metal layer.
It is preferable to include a step of forming a V film serving as the first brazing material layer. The joining process is 173.
It is preferable to carry out at the temperature of 0-1860 degreeC. The joining process is 1 to 200 kPa.
It is preferable to carry out while applying the pressure of. Moreover, it is preferable to perform a joining process in a vacuum or inert atmosphere.

ADVANTAGE OF THE INVENTION According to this invention, the target for X-ray tubes excellent in the joining strength under high temperature can be provided. In addition, since the bonding strength at high temperatures is excellent, a highly reliable X-ray detector can be obtained. In addition, since the amount of expensive material such as vanadium used can be reduced, the manufacturing cost can be reduced.

Sectional drawing which shows an example of the target for X-ray tubes of this invention. Sectional drawing which shows an example of the joining layer of this invention. Sectional drawing which shows another example of the joining layer of this invention. Sectional drawing which shows an example which provided the recessed part in the graphite base material of this invention. The figure which shows an example of the manufacturing method of this invention. The figure which shows an example of a test piece.

The X-ray tube target of the present invention has a structure in which a carbon base material and a Mo base material or Mo alloy base material are joined via a joining layer. FIG. 1 shows a cross section showing an example of an X-ray tube target. In the figure, 1 is an X-ray tube target, 2 is an Mo base (or Mo alloy base), 3
Is a bonding layer, 4 is a carbon substrate, and 5 is a hole for inserting a rotating shaft.
The Mo (molybdenum) substrate 2 is a member that becomes an electron beam irradiation surface. Since Mo has a high specific gravity, if the X-ray tube target is composed of only the Mo base, the target becomes heavy, and it is necessary to reinforce a holder (rotating shaft), a rotating mechanism (motor), and the like for high-speed rotation. Therefore, it is important to replace a part of the target with the carbon substrate 4. In addition, the Mo alloy is not particularly limited as long as it has high-temperature strength. For example, a Mo alloy containing Ti and Zr in a total amount of 0.2 to 10% by mass, or Ti, Zr, Hf, La, T
A Mo alloy containing 0.2 to 10% by mass of any one of a single metal, an oxide, and a carbide of a, Y, Nb, W, Re, and the like. Further, W (tungsten) or a Re—W alloy (rhenium tungsten alloy) may be provided on the electron beam irradiation surface as necessary. Moreover, a graphite base material etc. are mentioned as a carbon base material.

In order to achieve both the weight reduction of the X-ray tube target and the bonding strength at high temperatures, the bonding layer 3 for firmly bonding the Mo base 2 and the carbon base 4 is necessary. In the present invention, when the composition ratio of the bonding layer is detected by EPMA, the bonding layer is composed of a MoVX diffusion phase having a thickness of 1 to 100 μm, a VX alloy phase having a thickness of 10 to 500 μm, and an X-rich phase having a thickness of 1 to 600 μm. , Thickness 10-150
An XZr alloy phase of 0 μm, wherein X is at least one selected from Nb, Ta, and W;
It is characterized by comprising.
Note that EMPA is used in the present invention because it is possible to perform surface analysis in a very small region, which is difficult to perform by chemical analysis. Specifically, the bonding layer is first cut in the thickness direction and polished with a diamond grindstone or the like so that the surface roughness (Ra) of the cut surface is 1 μm or less. And EP
Qualitative and quantitative analysis is performed by MA.

An example of the bonding layer of the present invention is shown in FIG. In FIG. 2, 2 is an Mo base, 3 is a bonding layer, 4 is a carbon base, 6 is a MoVX diffusion phase, 7 is a VX alloy phase, 8 is an X-rich phase, and 9 is an XZr alloy phase.
The bonding layer of the present invention comprises V (vanadium), an X component (at least one selected from Nb, Ta, and W) and Zr (zirconium) as essential components.
In general, Zr and carbon can obtain a strong bond, while Zr and Mo form a eutectic alloy having a low melting point. When a eutectic alloy having a low melting point is present, the bonding strength at high temperatures is lowered. In order to prevent the formation of such a ZrMo eutectic alloy, it is desirable to install a V or X component between Zr and Mo. V and X components do not decrease in melting point even when alloyed with Mo.
It is effective in preventing r diffusion.
In general, in order to join V and Mo, the liquid phase must be changed to a temperature higher than the melting point of V (1890 ° C.). However, at very high temperatures (over 2200 ° C), M
o The mechanical strength of the substrate is greatly reduced, and the quality of the product is deteriorated. Moreover, if it joins at too high temperature, the diffusion of Zr will progress and a MoZr alloy with weak intensity | strength will be formed.
On the other hand, at a temperature of about 1400 ° C., the liquid phase is insufficient and the bonding strength is lowered. Therefore, in order to solve such a problem, the X component is used in the present invention. That is, the X component (Nb
, Ta, W) is used to prevent Zr from diffusing into the Mo substrate. Further, it is possible to perform bonding at a temperature at which V becomes a liquid phase while preventing diffusion of Zr.

From the above, the bonding layer of the present invention contains V (vanadium), X component (at least one selected from Nb, Ta, W) and Zr (zirconium) as essential components. Each phase will be described below.
The diffusion phase of MoVX is a phase formed by mutual diffusion of Mo and Mo used as a Mo base material, and V and X components, and forms a solid solution having a bcc crystal structure. The Mo content in the diffusion phase is an amount exceeding 10% by mass. The thickness of the diffusion phase of MoVX is 1 to 100 μm, preferably 10 to 50 μm.
The diffusion phase of MoVX is preferably formed on the Mo substrate as a continuous layer,
The diffusion phase should just be formed in 80% or more by the area ratio on Mo base material. On the other hand, when the thickness of the diffusion phase of MoVX is less than 1 μm, a portion where the diffusion phase is not formed is likely to occur (area ratio of 10
%). On the other hand, when the thickness exceeds 100 μm, not only the improvement effect of the bonding strength at high temperature is saturated, but also the thickness variation becomes large, and the bonding strength may be lowered. Further, the MoVX diffusion phase preferably comprises a solid solution of MoVX. By using a solid solution, it can be chemically stabilized.

The VX alloy phase has an X component of 10% by mass to 50% by mass and a Mo content of 10% by mass.
Hereinafter (including 0), it is the phase which is the balance V. As described above, the VX alloy phase preferably forms a solid solution of V and X components.
The thickness of the VX alloy phase is preferably 10 to 500 μm, more preferably 20 to 300 μm. If the thickness is less than 10 μm, there is a possibility that a portion that does not form a continuous layer is formed. Meanwhile, 30
If it exceeds 0 μm, the effect of providing the VX alloy phase is saturated. The NbTi alloy phase is preferably a continuous layer.
The X-rich phase is a phase in which the X component is 90% by mass or more and 100% by mass or less. As components other than X in the X-rich phase, V may be contained in an amount of 10% by mass or less (including 0), and Zr may be contained in an amount of 1% by mass or less (including 0). By providing the region having a V content of 10% by mass or less (including 0% by mass), it is possible to prevent Zr from diffusing more than necessary from the XZr alloy phase described later. By preventing the diffusion of Zr more than necessary, it is possible to prevent the formation of a low melting point MoZr eutectic alloy. The X-rich phase preferably has a thickness of 1 to 600 μm. 1μm
If it is less than the range, the effect of preventing the diffusion of Zr may be insufficient, and if it exceeds 600 μm, the effect of preventing the diffusion of Zr cannot be improved. A more preferable thickness of the X-rich phase is 30 to 400 μm.
As the X component, Nb is preferable among Nb, Ta, and W because of its low price.

The XZr alloy phase is a Zr phase containing an X component. This XZr alloy phase is Z
In some cases, r reacts with carbon to form a ZrC phase. Further, the ZrC phase is fine precipitation (precipitation of fine particles) due to the reaction of Zr and C, and has the effect of increasing the mechanical strength of the XZr alloy phase by dispersing fine precipitates in the XZn alloy phase. Bonding strength at high temperatures can be further improved. The XZr alloy phase is preferably a continuous layer. The ZrC phase is XZ as shown in FIG. 3 (in FIG. 3, 9 is the XZr alloy phase and 10 is the ZrC phase).
It is preferably in a state of being finely dispersed in the r alloy phase, and 0.1 to several percent in the XZr alloy phase.
If present (volume ratio), the effect is sufficient. Moreover, the thickness is 10-1500 micrometers, Furthermore, 100-500 micrometers is preferable.
The bonding layer as described above preferably has a total thickness of 20 to 2000 μm. The bonding layer is a range in which the thicknesses from the diffusion phase of MoNbTi to the ZrNb alloy phase (including the ZrC phase when there is a ZrC phase) are totaled. Further, when the thickness of the bonding layer is not uniform (for example, when a concave portion is provided on a bonding surface described later), the shortest distance is set as the thickness of the bonding layer.

By providing such a bonding layer, it is possible to obtain an X-ray tube target having a high bonding strength at a high temperature while reducing the amount of expensive vanadium used.
It is also effective to provide a concave portion on the bonding layer contact surface of the carbon substrate in order to further increase the bonding strength. FIG. 4 shows an example in which a recess is provided. In FIG. 4, 4 is a carbon substrate, 9 is an XZr alloy phase, and 11 is a recess. An anchor effect can be obtained by providing the recess. The concave portion is not limited to the V (buoy) shape shown in FIG. 4, and may include a concave cross section, a U shape, and the like. Moreover, a recessed part is not specifically limited, such as a dot shape, a vertical groove | channel, a horizontal groove | channel, a grid | lattice shape, a circular shape, a polygonal shape, and a spiral shape. Moreover, it is preferable to provide a recessed part in 50% or more of area ratio of a graphite base-material joint surface, and also 80% or more of range. If it is less than 50%, the effect of providing a recess is small.
Since the X-ray tube target of the present invention is excellent in bonding strength at high temperature, 2000 rpm
As described above, it is optimal when used for an X-ray tube rotating at a high speed of over 10,000 rpm, a large target having a diameter of 9 cm or more, a high output X-ray tube having an applied voltage of 100 kV or more, and the like. for that reason,
By using the X-ray tube target of the present invention, the reliability of the X-ray inspection apparatus can be improved.

The production method of the X-ray tube target of the present invention is not particularly limited as long as it has the above-described configuration, but the following method can be mentioned as a method for obtaining it efficiently.
First, as the brazing material layer, a first brazing material layer made of V having a thickness of 0.001 mm or more and less than 0.01 mm, at least one selected from Nb, Ta, and W having a thickness of 0.1 to 0.6 mm is used. A brazing filler metal layer producing step is carried out for producing a second brazing filler metal layer as a main component and a third brazing filler metal layer made of Zr having a thickness of 0.1 to 0.3 mm.
As a method for producing the brazing material layer, there are a method of installing a foil body of each metal, a method of applying each metal powder in a paste form, and the like.
Further, the brazing material layer production step can be a step of producing a clad material of the first brazing material layer, the second brazing material layer, and the third brazing material layer. With this method, it is easy to control each brazing filler metal layer to a uniform thickness as compared with the method of applying a metal paste.
Further, the brazing material layer manufacturing step can include a step of forming a V film to be the first brazing material layer on the second brazing material layer. If this method is used, the V layer can be thinned, which is particularly effective when it is desired to reduce the amount of expensive V used.
FIG. 5 shows an example of a process for providing a brazing material layer. In FIG. 5, 2 is a Mo substrate, 4 is a carbon substrate, 1
2 is a first brazing filler metal layer, 13 is a second brazing filler metal layer, and 14 is a third brazing filler metal layer. Step of installing each brazing filler metal layer between Mo base and carbon base so as to have a laminated structure of Mo base / first brazing filler metal layer / second brazing filler metal layer / third brazing filler metal layer / carbon base material I do.
Moreover, it is preferable to use each brazing material layer having a high purity of 98% or more.

Further, the thickness of the first brazing filler metal layer is 0.001 mm or more and less than 0.01 mm, and further 0.00
A range of 3 to 0.008 mm is preferable. The thickness of the first brazing material layer is 0.001 mm
If the amount is less than 1, the amount of vanadium is too small, and a uniform MoVX diffusion phase may not be formed. On the other hand, if it is 0.01 mm or more, the effect of using vanadium is not only saturated, but also causes an increase in cost.
The second brazing filler metal layer has a thickness of 0.1 to 0.6 mm, and the third brazing filler metal layer has a thickness of 0.1 to 0.3 m.
A range of m is preferable. If the thickness of the second brazing material layer is less than 0.1 mm, there is a possibility that Zr diffusion cannot be sufficiently prevented. The thickness of the third brazing filler metal layer (Zr layer) is 0.1 mm.
If it is less than the range, the bonding strength with the carbon substrate may be lowered. On the other hand, the thickness of the second brazing filler metal layer is 0.
If the thickness exceeds 6 mm or the thickness of the third brazing filler metal layer exceeds 0.3 mm, the target joining layer may not be obtained, and the brazing material that has become a liquid phase during the joining process may be used as a target. There is a high risk of leakage to the outside.
Next, the joining process which joins what was made into the laminated structure at the temperature of 1730-1900 degreeC is performed. At this time, when the temperature is lower than 1730 ° C., each brazing filler metal layer is not sufficiently liquid phase. Also 1900
If it exceeds ° C., the mechanical strength of the Mo substrate may be significantly deteriorated. A more preferable temperature is 1730 to 1860 ° C. If the temperature is equal to or lower than the melting point of Zr (1852 ° C.), the risk of Zr leaking out of the target is low.

Moreover, when joining, it is desirable to carry out while applying a pressure of 1 to 200 kPa. Bonding strength can be improved by bonding while applying pressure. Moreover, even if the vanadium layer is thin, sufficient bonding strength can be obtained. If the pressure is less than 1 kPa, the effect of applying pressure is insufficient, and if it exceeds 200 kPa, the brazing filler metal layer becomes a liquid phase at the time of joining and may overflow from the target. A more preferable pressure is 2 to 50 kPa.
Moreover, it is preferable to perform a joining process in a vacuum or non-oxidizing atmosphere. The vacuum is preferably 1 × 10 ⁻² Pa or less. Examples of the non-oxidizing atmosphere include nitrogen and argon atmospheres, and an argon atmosphere is particularly preferable. Moreover, it can prevent that a brazing filler metal layer is oxidized more than necessary by performing in a vacuum or non-oxidizing atmosphere. When joining, heat treatment in a hydrogen atmosphere is also effective as a pretreatment. By exposing the bonding surface to a hydrogen atmosphere in this manner, adsorbed oxygen, oxides, and the like that can hinder bonding can be removed, and the bonding strength can be further increased.

Moreover, although the heating time at the time of joining is based on the said conditions, holding | maintenance of 1 minute-1 hour is preferable. The heating time is 1 minute after the temperature of the bonding layer falls within the range of ± 10 ° C. with respect to the target bonding temperature.
It is preferable to hold for 1 hour.
Moreover, after joining, post-processes, such as a side surface grinding | polishing process, are performed as needed. Furthermore, when assembling into an X-ray tube, it is assembled by being joined to a rotating shaft (shaft). The X-ray tube target of the present invention is suitable for a rotating anode, and is excellent in high-temperature strength, so a large target having a rotational speed of 2000 rpm or more, a diameter of 9 cm or more, further 12 cm or more, or an applied voltage of 100 kV or more, high speed, large size, high Suitable for output X-ray tube. Further, an X-ray inspection apparatus can be obtained by combining the X-ray tube of the present invention with a detector such as a scintillator. Since the X-ray tube can cope with high speed, large size or high output, the performance as an X-ray inspection apparatus can be improved. In particular, it is suitable for an X-ray inspection apparatus for CT and an X-ray inspection apparatus for fluoroscopy. CT is an inspection apparatus that can process an image three-dimensionally (three-dimensional image), and the one for fluoroscopy is an inspection apparatus that can obtain a two-dimensional image in a shorter time than CT. In either case, high speed, large size or high output of the X-ray tube is required.

[Example]
Hereinafter, embodiments of the present invention will be specifically described with reference to examples and comparative examples.
Example 1
As a first brazing material layer, a 0.005 mm thick V foil (purity 99% by mass or more), as a second brazing material layer 0.3 mm thick Nb foil (purity 99% by mass or more), as a third brazing material layer Thickness 0.2
A foil brazing filler metal layer of mm Zr foil (purity 98 mass% or more) was prepared.
After being laminated so as to be Mo base / first brazing filler metal layer / second brazing filler metal layer / third brazing filler metal layer / graphite base material, in vacuum (1 × 10 ⁻² Pa or less), 1850 ° C. × 30 Minute, pressure addition 1
The X-ray tube target according to Example 1 was manufactured by bonding under the condition of 0 kPa. The diameter of the target is 10 cm, and 0.5 mass% of Ti is used as the Mo base.
The Mo alloy base material which consists of 0.08 mass% r and remainder Mo was used. Further, a groove having a V-shaped cross section was formed in a spiral shape on the joining surface side of the graphite base material with an area ratio of 80% or more.
The joint section of the obtained X-ray tube target was cut out and polished until the surface roughness Ra became 1 μm, and then the composition, thickness, etc. of each phase of the joint section were investigated by EPMA. The results are shown in Table 2.
(Examples 2 to 6)
What changed the thickness of the brazing filler metal layer, the alloy composition, the joining conditions and the like as shown in Table 1 was prepared, and investigated by EPMA in the same manner as in Example 1. The results are shown in Table 2. In the brazing material manufacturing step, “V film formation by sputtering” means that a vanadium film was formed on the surface of the second brazing material foil by sputtering. Further, “processing into a clad material in advance” indicates that the first to third brazing material foils are integrated with the clad material in the rolling process.

(Comparative Example 1)
A Zr foil with a thickness of 100 μm and a Mo substrate are placed on a graphite substrate in vacuum (1 × 10
⁻² Pa or less), 1720 ° C. × 5 minutes, and pressure was applied under the conditions of 10 kPa.
(Comparative Example 2)
A laminated structure of Mo base material / vanadium foil with a thickness of 0.07 mm / tungsten foil with a thickness of 0.3 mm / NbZr alloy (Nb 20 mass%) with a thickness of 0.1 mm / graphite base material in a vacuum (10 ^{− (4} Torr or less) 1700 ° C. × 10 minutes, no pressure was applied, and heat bonding was performed.

As can be seen from Table 2, the bonding layer of the X-ray tube target according to the example had a predetermined phase structure. Moreover, all the MoVX diffusion phases of the examples were solid solutions. Further, the VX alloy phase was a region where Mo was 10% by mass or less. The X-rich phase was an area where the X component was 90% by mass or more (the remaining V was 10% by mass or less and Zr was 1% by mass or less). Further, although there was a ZrC phase in the XZr alloy phase, all were in the range of 0.2 to 2.5% by volume ratio.
Next, a test piece as shown in FIG. 6 was cut out from the X-ray tube target according to Examples and Comparative Examples, and the bending strength of the bonding layer was measured by a four-point bending method. At that time, the test piece was heated in a vacuum from room temperature to a high temperature region, the bending strength at each temperature was measured, and the temperature (joining heat resistance temperature) immediately before the strength suddenly decreased was investigated. The results are shown in Table 3.

The X-ray tube target according to this example has a high temperature strength equal to or higher than that of the comparative example.
In other words, despite the same characteristics, excellent bonding strength was obtained by reducing the amount of expensive vanadium used.

DESCRIPTION OF SYMBOLS 1 ... Target for X-ray tubes 2 ... Mo base material 3 ... Joining layer 4 ... Graphite base material 5 ... Hole 6 ... MoNbTi diffusion phase 7 ... NbTi alloy phase 8 ... Nb rich phase 9 ... ZrNb alloy phase 10 ... ZrC phase 11 ... concave portion 12 ... first brazing filler metal layer 13 ... second brazing filler metal layer 14 ... third brazing filler metal layer

Claims (14)

In the X-ray tube target in which the carbon base material and the Mo base material or the Mo alloy base material are joined via the joining layer, when the composition ratio of the joining layer is detected by EPMA, the joining layer has a thickness of 1 to 1. 100 μm MoVX diffusion phase, 10-500 μm thick VX alloy phase, 1-6 thick
00 μm X-rich phase, 10 to 1500 μm thick XZr alloy phase, where X is Nb, T
A target for an X-ray tube, comprising at least one selected from a and W. The X-ray tube target according to claim 1, wherein the MoVX diffusion phase comprises a solid solution of MoVX. The X-ray tube target according to claim 1, wherein the VX alloy phase has a Mo content of 10 mass% or less (including 0). 4. The X-rich phase is characterized in that X is 90% by mass or more.
The target for X-ray tubes of any one of these. The X-ray tube target according to any one of claims 1 to 4, wherein the XZr alloy phase includes a ZrC phase. An X-ray detector comprising the X-ray tube target according to any one of claims 1 to 5. An X-ray inspection apparatus using the X-ray detector according to claim 6. The X-ray inspection apparatus according to claim 7, which is used for CT or fluoroscopy. In the method for producing a target for an X-ray tube in which a carbon base material and a Mo base material or a Mo alloy base material are joined via a joining layer, a thickness of 0 is provided between the carbon base material and the Mo base material or the Mo alloy base material. .00
First brazing filler metal layer made of V having a thickness of 1 mm or more and less than 0.01 mm, Nb having a thickness of 0.1 to 0.6 mm
, Ta, W, the second brazing filler metal layer, the main component of which is at least one selected from the group consisting of Ta and W,
A brazing filler metal layer producing step for producing a third brazing filler metal layer made of 0.3 mm of Zr, and 1730-
The manufacturing method of the target for X-ray tubes characterized by comprising the joining process joined at the temperature of 1900 degreeC. 10. The method of manufacturing an X-ray tube target according to claim 9, wherein the brazing material layer manufacturing step is a step of manufacturing a clad material of the first brazing material layer, the second brazing material layer, and the third brazing material layer. . The X-ray tube target according to claim 9, wherein the brazing material layer manufacturing step includes a step of forming a V film serving as the first brazing material layer on the second brazing material layer. Manufacturing method. The method for manufacturing a target for an X-ray tube according to any one of claims 9 to 11, wherein the joining step is performed at a temperature of 1730 to 1860 ° C. The method for manufacturing a target for an X-ray tube according to any one of claims 9 to 12, wherein the joining step is performed while applying a pressure of 1 to 200 kPa. The method for manufacturing a target for an X-ray tube according to any one of claims 9 to 13, wherein the joining step is performed in a vacuum or in an inert atmosphere.

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