Heat transfer member

Abstract

A heat transfer member according to one aspect of the present disclosure includes a first heat transfer body and a second heat transfer body. The first heat transfer body has a graphite block having a structure obtained by stacking a plurality of graphenes. The graphite block has a first surface located at one end in the stacking direction of the graphene, and a hole that opens in the first surface. The second heat transfer body is located in the hole and is thermally connected to the graphite block inside the hole. In the stacking direction, the thermal conductivity of the second heat transfer body is higher than the thermal conductivity of the first heat transfer body. In a direction perpendicular to the stacking direction, the thermal conductivity of the second heat transfer body is lower than the thermal conductivity of the first heat transfer body. A side surface of the graphite block is inclined relative to the stacking direction.

Description

Heat transfer components

[0001] This disclosure relates to a heat transfer component.

[0002] Traditionally, X-ray tubes have been used in medical equipment such as CT (Computed Tomography) scanners and X-ray machines, as well as in industrial non-destructive testing equipment. An X-ray tube is a device that generates X-rays by accelerating thermionic electrons generated at the cathode with an electric field and causing them to collide with the anode, thereby creating an impact.

[0003] The anode, which receives thermionic electrons, reaches temperatures of over 1000°C. Therefore, to reduce the localized temperature rise of the anode, a rotating anode X-ray tube is known that disperses the heat of the anode by rotating an umbrella-shaped anode at high speed (see Patent Document 1).

[0004] U.S. Patent Application Publication No. 2023 / 0079317

[0005] A heat transfer member according to one aspect of the present disclosure comprises a first heat transfer element and a second heat transfer element. The first heat transfer element has a graphite block having a structure in which a plurality of graphenes are stacked. The graphite block has a first surface located at one end in the direction of graphene stacking and a hole opening to the first surface. The second heat transfer element is located in the hole and is thermally connected to the graphite block inside the hole. In the stacking direction, the thermal conductivity of the second heat transfer element is higher than that of the first heat transfer element. In a direction perpendicular to the stacking direction, the thermal conductivity of the second heat transfer element is lower than that of the first heat transfer element. The side surface of the graphite block is inclined with respect to the stacking direction.

[0006] Figure 1 is a cross-sectional view showing an example of the configuration of a heat transfer member according to the first embodiment. Figure 2 is a plan view showing an example of the configuration of a heat transfer member according to the first embodiment. Figure 3 is a cross-sectional view showing an example of the configuration of a heat transfer member according to the second embodiment. Figure 4 is a cross-sectional view showing another example of the configuration of a heat transfer member according to the second embodiment. Figure 5 is a perspective view showing an example of the configuration of a heat transfer member according to the third embodiment. Figure 6 is a cross-sectional view showing an example of the configuration of a heat transfer member according to the third embodiment.

[0007] The conventional technology described above has room for further improvement in terms of improving thermal conductivity. "Improving thermal conductivity" here means efficiently transferring heat from a heat source (the anode in the example of a rotating anode X-ray tube) to a location away from the heat source. The challenge of "improving thermal conductivity" is not limited to the anode of the rotating anode X-ray tube described above, but can also arise for various components or heat-generating elements that receive heat from a heat source. This disclosure provides a technology that can improve thermal conductivity.

[0008] The embodiments for implementing the heat transfer member according to this disclosure (hereinafter referred to as "embodiments") will be described in detail below with reference to the drawings. However, this disclosure is not limited by these embodiments. Furthermore, each embodiment can be combined as appropriate, provided that the processing content is not inconsistent. Also, the same parts are denoted by the same reference numerals in each of the following embodiments, and redundant descriptions are omitted.

[0009] Furthermore, in the embodiments described below, expressions such as "constant," "orthogonal," "perpendicular," or "parallel" may be used, but these expressions do not require strict adherence to "constant," "orthogonal," "perpendicular," or "parallel" conditions. In other words, each of the above expressions allows for deviations, for example, in manufacturing accuracy or installation accuracy.

[0010] <First Embodiment> First, the configuration of the heat transfer member 1 according to the first embodiment will be described with reference to Figures 1 and 2. Figure 1 is a cross-sectional view showing an example of the configuration of the heat transfer member 1 according to the first embodiment. Figure 2 is a plan view showing an example of the configuration of the heat transfer member 1 according to the first embodiment. Note that Figure 1 corresponds to a cross-sectional view of the heat transfer member 1 along the dotted line connecting L1 and L2 shown in Figure 2.

[0011] (Heat transfer member) As shown in Figures 1 and 2, the heat transfer member 1 may have a first heat transfer element 10 and a second heat transfer element 20. The first heat transfer element 10 may have a graphite block 11 and a hole 12.

[0012] The graphite block 11 may be a laminate having a structure in which multiple graphene 13 are stacked in one direction. The graphene 13 may be a sheet-like material in which a honeycomb structure, composed of bonded carbon atoms, extends in two dimensions. The graphene 13 may be bonded to each other by intermolecular forces, such as van der Waals forces.

[0013] In the first embodiment, a plurality of graphene 13 are stacked in the Z-axis direction. That is, the honeycomb structure of graphene 13 may extend along the XY plane perpendicular to the Z-axis direction.

[0014] The graphite block 11 may be, for example, a plate-shaped member with a circular shape in plan view (see Figure 2). The graphite block 11 may have a first surface 111, a second surface 112 located opposite the first surface 111, and a side surface 113 connecting the first surface 111 and the second surface 112.

[0015] As will be described in more detail later, in this disclosure, the side surface 113 may be inclined with respect to the stacking direction of the plurality of graphenes 13, i.e., the Z-axis direction. In other words, in this disclosure, the graphite block 11 may have a frustoconical shape.

[0016] The first surface 111 may extend along the XY plane and be located at one end (in this case, the end on the negative Z-axis side) in the stacking direction of the multiple graphenes 13. The second surface 112 may extend along the XY plane and be located at the other end (in this case, the end on the positive Z-axis side) in the stacking direction of the graphenes 13.

[0017] The graphite block 11 has anisotropy in its thermal conductivity. Specifically, the graphite block 11 may have very high thermal conductivity in the direction along the crystal plane, in this case, in the XY plane.

[0018] The thermal conductivity of the graphite block 11 in the direction along the crystal plane may be, for example, 200 W / m·K or more. On the other hand, the thermal conductivity of the graphite block 11 in the stacking direction of the graphene 13 may be, for example, 7 W / m·K.

[0019] The thermal conductivity of the graphite block 11 in the direction along the crystal plane may preferably be 370 W / m·K or higher. More preferably, it may be 450 W / m·K or higher. Even more preferably, it may be 800 W / m·K or higher. In the first embodiment, the thermal conductivity of the graphite block 11 in the direction along the crystal plane may be 1200 W / m·K or higher, more specifically, about 1700 W / m·K.

[0020] The graphite block 11 may be made of a specific material whose main component is pyrolytic graphite. In this disclosure, "main component" means, for example, that it has a volume ratio of 50% or more. The graphite block 11 may be made of pyrolytic graphite with a volume ratio of 95% or more, or it may be a substantially pure carbon material with a volume ratio of 99% or more pyrolytic graphite. If the graphite block 11 is a substantially pure carbon material, the stress applied to the graphite block 11 due to the thermal expansion of impurities present inside the graphite block 11 is suppressed. In addition, the decrease in thermal conductivity in the direction along the crystal plane of the graphite block 11 due to impurities present inside the graphite block 11 is suppressed.

[0021] Pyrolytic graphite may be produced, for example, as follows: For example, pyrolytic graphite is produced by vapor deposition and layering of hydrocarbons, and then subjected to a pressurized annealing treatment to produce highly oriented pyrolytic graphite having a thermal conductivity of about 1700 W / m·K.

[0022] The side surface 113 may be inclined with respect to the stacking direction of the graphene 13. Specifically, the side surface 113 may be inclined in a direction in which the dimensions of the graphite block 11 in a direction perpendicular to the stacking direction of the graphene 13 increase toward the first surface 111.

[0023] In such a case, the ends of the surfaces of the graphene 13 constituting the graphite block 11 that face adjacent graphene 13 may be exposed to the outside. That is, at the end of each graphene 13, the crystal plane may be exposed toward the positive Z-axis direction. Such a surface 113 may be a stepped surface formed by the ends of the multiple graphene 13.

[0024] With this configuration, for example, if there is a heat source on the second surface 112 side, the heat from the heat source can be directly received by the side surface 113. Specifically, not only the graphene 13 facing the heat source (the graphene 13 located on the second surface 112), but also the ends of the other multiple graphenes 13 can directly receive heat. The heat received by the side surface 113 moves along the crystal plane of each graphene 13 and is then conducted to the second heat transfer body 20, which will be described later.

[0025] The hole 12 opens into the first surface 111 of the graphite block 11. The hole 12 may extend along the stacking direction of the graphene 13 and penetrate the graphite block 11. That is, the hole 12 may open into the first surface 111 and the second surface 112 of the graphite block 11.

[0026] The hole 12 may be located in the center of the first surface 111 of the graphite block 11. The shape of the opening surface of the hole 12 may be, for example, circular (see Figure 2). The shape of the opening surface of the hole 12 is not particularly limited and may be, for example, square.

[0027] The second heat transfer element 20 is located in the hole 12 of the graphite block 11 and may be thermally connected to the graphite block 11 inside the hole 12. The second heat transfer element 20 may be, for example, a cylindrical member. Specifically, as will be described later, the second heat transfer element 20 and the graphite block 11 may be joined by, for example, the first joining material 30 described later. The shape of the second heat transfer element 20 is not particularly limited and can be appropriately changed to match the shape of the opening surface of the hole 12.

[0028] In the stacking direction of the graphene 13, the thermal conductivity of the second heat transfer element 20 is higher than that of the graphite block 11. Furthermore, in a direction perpendicular to the stacking direction of the graphene 13, the thermal conductivity of the second heat transfer element 20 is lower than that of the graphite block 11. As such a second heat transfer element 20, for example, a metallic material such as copper, silver, aluminum-based metals, or stainless steel may be used.

[0029] Not limited to the metal materials mentioned above, the second heat transfer body 20 may be, for example, a carbon material, or more specifically, a material made by stacking multiple graphenes, similar to the graphite block 11. In such a case, it is preferable that the graphite block 11 constituting the second heat transfer body 20 has multiple graphenes stacked in a direction perpendicular to the stacking direction of the multiple graphenes 13 constituting the graphite block 11. Alternatively, the second heat transfer body 20 may be, for example, a ceramic material such as AlN (aluminum nitride).

[0030] As described above, the graphite block 11, which has a structure in which multiple graphene 13 are stacked, has anisotropy in thermal conductivity, having very high thermal conductivity in the direction along the crystal plane, while having relatively low thermal conductivity in the stacking direction. In contrast, the heat transfer member 1 according to the first embodiment has a second heat transfer body 20 whose thermal conductivity in the stacking direction is higher than that of the graphite block 11.

[0031] The second heat transfer element 20 functions as a heat conduction path in the stacking direction. That is, the heat received on the side surface 113 of the graphite block 11 is conducted to the second heat transfer element 20 by moving along the crystal plane of the graphite block 11, and then moves through the second heat transfer element 20 in the stacking direction, specifically in the negative Z-axis direction.

[0032] With this second heat transfer element 20, the heat conducted from the graphite block 11 can be effectively moved along the stacking direction. This allows the heat to be effectively moved to a location away from the heat source, specifically to the negative Z-axis direction.

[0033] Thus, the heat transfer member 1 according to the first embodiment effectively receives heat from a heat source on the side surface 113 of the graphite block 11, efficiently conducts this heat to the second heat transfer body 20 via the graphite block 11, and efficiently moves it to a location away from the heat source via the second heat transfer body 20.

[0034] One end of the second heat transfer element 20 may protrude from the first surface 111. Similarly, the other end of the second heat transfer element 20 may protrude from the second surface 112. However, one end of the second heat transfer element 20 may be flush with the first surface 111, and the other end of the second heat transfer element 20 may be flush with the second surface 112.

[0035] Alternatively, one end of the second heat transfer element 20 may be located inside the hole 12, and the other end of the second heat transfer element 20 may also be located inside the hole 12. The second heat transfer element 20 only needs to be located in the internal region of the hole 12 that includes at least the central part of the graphite block 11 in the stacking direction of the graphene 13.

[0036] In this configuration, the hole 12 penetrates the graphite block 11, and the second heat transfer element 20 is filled into the hole 12, thereby effectively transferring heat from the heat source to the second heat transfer element 20. Specifically, by reducing the heat conduction path between the side surface 113 of the graphite block 11 and the second heat transfer element 20, the heat received by the side surface 113 can be effectively transferred to the second heat transfer element 20. Furthermore, since the heat from the heat source can be directly received by the second heat transfer element 20, the heat transfer performance of the heat transfer member 1 can be improved.

[0037] Preferably, one end of the second heat transfer element 20 protrudes from the first surface 111. With this configuration, the heat conducted from the graphite block 11 can be moved to a location further away from the heat source, specifically to a location further away in the negative Z-axis direction.

[0038] As described above, the second heat transfer body 20 may be located in the internal region of the hole 12 that opens at the center of the first surface 111 of the graphite block 11. According to such a configuration, the side surfaces 113 are symmetrically located with respect to the second heat transfer body 20. For this reason, the variation in the distance from the end of each graphene 13 forming the side surface 113 to the second heat transfer body 20 is small, and the temperature variation of the graphite block 11 is small. Therefore, the thermal conductivity of the first heat transfer body 10 can be increased.

[0039] In the stacking direction of the graphene 13, the coefficient of thermal expansion of the first heat transfer body 10 may be higher than the coefficient of thermal expansion of the second heat transfer body 20. According to such a configuration, by the second heat transfer body 20 restraining the thermal expansion of the first heat transfer body 10 in the stacking direction of the graphene 13, it is possible to reduce the dimensional change when the temperature of the heat transfer member 1 changes.

[0040] Specifically, the coefficient of thermal expansion of the graphite block 11 in the stacking direction of the graphene 13 may be, for example, 20×10 －６ / K or more. In the present disclosure, when simply described as "coefficient of thermal expansion", it means the linear expansion coefficient.

[0041] More specifically, the coefficient of thermal expansion of the graphite block 11 in the stacking direction of the graphene 13 may be about 24×10 －６ / K. Also, the coefficient of thermal expansion of the graphite block 11 in the stacking direction of the graphene 13 may be 27×10 －６ / K or less.

[0042] In the direction orthogonal to the stacking direction of the graphene 13, that is, in the direction along the crystal plane, the coefficient of thermal expansion of the first heat transfer body 10 may be lower than the coefficient of thermal expansion of the second heat transfer body 20. According to such a configuration, when the temperature of the heat transfer member 1 rises, the second heat transfer body 20 expands more than the first heat transfer body 10, so the adhesion between the second heat transfer body 20 and the first heat transfer body 10 is improved. As a result, heat is more easily transferred from the first heat transfer body 10 to the second heat transfer body 20, so the thermal conductivity of the heat transfer member 1 can be increased.

[0043] Specifically, the coefficient of thermal expansion of the graphite block 11 in the direction along the crystal plane may be, for example, 0.050×10 －６ / K or the like.

[0044] Note that the coefficient of thermal expansion of the graphite block 11 in the direction along the crystal plane may be a negative value. Specifically, it may be −0.001×10 －６ / K or less. The coefficient of thermal expansion of the graphite block 11 in the direction along the crystal plane may be −0.01×10 －６ / K or more.

[0045] In the present embodiment, the inclination angle of the side surface 113 may be adjusted so that the difference between the coefficient of thermal expansion of the side surface 113 in the direction in which the side surface 113 extends and the coefficient of thermal expansion of a first member 50 (see the third embodiment) described later becomes small. That is, the absolute value of the difference between the coefficient of thermal expansion of the side surface 113 in the direction in which the side surface 113 extends and the coefficient of thermal expansion of the first member 50 may be smaller than the absolute value of the difference between the coefficient of thermal expansion of the graphite block 11 in the stacking direction and the coefficient of thermal expansion of the first member 50. In this case, compared with the case where the side surface 113 is not inclined, the stress at the boundary between the side surface 113 and the first member 50 that may be caused by the difference in the coefficient of thermal expansion can be reduced. Hereinafter, the coefficient of thermal expansion of the side surface 113 in the direction in which the side surface 113 extends will be simply referred to as "the coefficient of thermal expansion of the side surface 113".

[0046] The coefficient of thermal expansion of the side surface 113 changes according to the inclination angle of the side surface 113. Specifically, the coefficient of thermal expansion of the side surface 113 increases as the inclination angle of the side surface 113 approaches 90°, and decreases as the inclination angle of the side surface 113 approaches 0°. This is because as the inclination angle approaches 90°, the influence of the coefficient of thermal expansion of the graphene 13 in the stacking direction on the coefficient of thermal expansion of the side surface 113 increases. Note that the inclination angle may be 89° or less and 5° or more. In this case, the coefficient of thermal expansion of the side surface 113 is a value in the range of 0.50×10 －６ / K to 24×10 －６ / K. Further, the inclination angle may be 70° or less and 25° or more. In this case, the coefficient of thermal expansion of the side surface 113 is 5.0×10 －６ / K to 20×10 －６The value will be within the range of / K.

[0047] In the stacking direction of the graphene 13, the toughness of the first heat transfer element 10 may be lower than that of the second heat transfer element 20. With this configuration, the second heat transfer element 20 restrains the first heat transfer element 10, thereby reducing the stress applied to the heat transfer member 1 due to repeated thermal expansion and contraction.

[0048] The second heat transfer element 20 may be bonded to multiple graphene 13 within the hole 12. The multiple graphene 13 are bonded by intermolecular forces. For this reason, if the second heat transfer element 20 is bonded to a single graphene 13, for example, if an external force is applied to the second heat transfer element 20, the graphene 13 bonded to the second heat transfer element 20 is likely to peel off from the graphite block 11. In contrast, if the second heat transfer element 20 is bonded across multiple graphene 13, peeling of the graphene 13 is less likely to occur. Therefore, with this configuration, the adhesion between the second heat transfer element 20 and the first heat transfer element 10 is high.

[0049] Specifically, the heat transfer member 1 according to the first embodiment may have a first joining material 30 between the hole 12 and the second heat transfer body 20. For example, a brazing material may be used as the first joining material 30. For example, titanium brazing material may be used. Alternatively, a brazing material other than titanium brazing material may be used, such as silver brazing material, copper brazing material, or aluminum brazing material.

[0050] With this configuration, the bonding force between the first heat transfer element 10 and the second heat transfer element 20 can be increased. For example, when titanium brazing material is used as the first bonding material 30, a layer of titanium carbide is formed at the interface between the graphite block 11 and the first bonding material 30, thereby increasing the bonding force between the graphite block 11 and the second heat transfer element 20.

[0051] The surface roughness of the inner circumferential surface of the hole 12 may be greater than the surface roughness of the first surface 111 and the second surface 112. The rougher inner circumferential surface of the hole 12 increases the contact area between the hole 12 and the first joining material 30. As a result, the adhesion force between the hole 12 and the first joining material 30 is increased, and the bonding force between the first heat transfer element 10 and the second heat transfer element 20 can be improved.

[0052] Specifically, the surface roughness of the inner circumferential surface of the hole 12 may be 20 times or more the surface roughness of the first surface 111 and the second surface 112, or it may be 10 times or more but less than 20 times, or it may be 5 times or more but less than 10 times. Furthermore, the surface roughness of the inner circumferential surface of the hole 12 may be less than the surface roughness of the first surface 111 and the second surface 112.

[0053] In this disclosure, "surface roughness" means the arithmetic mean roughness Ra as defined in JIS B 0601:2001.

[0054] Multiple graphene 13 ends are exposed on the inner circumferential surface of the hole 12. The positions of the multiple graphene 13 ends exposed on the inner circumferential surface of the hole 12 are misaligned. In other words, when the inner circumferential surface of the hole 12 is viewed at the molecular level, it has irregularities due to the misalignment of the ends of the multiple graphene 13. In this way, the presence of fine irregularities at the molecular level on the inner circumferential surface of the hole 12 increases the contact area between the hole 12 and the first bonding material 30. As a result, the adhesion force between the hole 12 and the first bonding material 30 is increased, and the bonding force between the first heat transfer body 10 and the second heat transfer body 20 can be improved.

[0055] In the first embodiment, the second heat transfer element 20 may be rotatable around the Z-axis (θ-direction). Specifically, one end of the second heat transfer element 20 protruding from the first surface 111 may be connected to a rotation mechanism or the like (not shown). By rotating the second heat transfer element 20 around the Z-axis in this way, the heat transfer member 1 can also be rotated around the Z-axis. Such a configuration can be used, for example, in an X-ray tube. This point will be discussed later with reference to Figures 5 and 6.

[0056] <Second Embodiment> Next, the configuration of the heat transfer member 1 according to the second embodiment will be described with reference to Figures 3 and 4. Figure 3 is a cross-sectional view showing an example of the configuration of the heat transfer member 1 according to the second embodiment.

[0057] The first heat transfer body 10 according to the second embodiment may have a plating layer 40 covering the graphite block 11. That is, the heat transfer member 1 according to the second embodiment corresponds to a configuration in which a plating layer 40 is provided on the surface of the graphite block 11 according to the first embodiment.

[0058] As shown in Figure 3, the plating layer 40 may cover the entire graphite block 11. That is, the plating layer 40 may be located on the surface of the first surface 111, the second surface 112, the side surface 113, and the hole 12. The plating layer 40 may be made of, for example, Ni (nickel) or Cu (copper). The plating layer 40 can be formed by, for example, electroplating.

[0059] The graphite block 11 has the property that when stress is generated along the plane direction of the crystal plane, the graphene 13 located on the crystal plane is prone to peeling. In contrast, by covering the graphite block 11 with a plating layer 40, the occurrence of peeling or damage to the graphene 13 can be reduced, and high toughness of the heat transfer member 1 can be achieved. Furthermore, the diffusion of fragments of the graphite block 11 into the surroundings can be reduced.

[0060] Figure 4 is a cross-sectional view showing another example of the configuration of the heat transfer member 1 according to the second embodiment. The plating layer 40 may be provided so as to cover at least a portion of the area of ​​the graphite block 11 other than the hole 12. Specifically, as shown in Figure 4, for example, the plating layer 40 may be located only on the surface of the first surface 111, the second surface 112, and the side surface 113.

[0061] With this configuration, heat can be efficiently conducted from the graphite block 11 to the second heat transfer body 20 compared to the case where the hole 12 is covered with the plating layer 40. Specifically, since the thermal conductivity of the plating layer 40 is smaller than the thermal conductivity of the graphite block 11 in the direction perpendicular to the stacking direction of the graphene 13, heat can be efficiently conducted to the second heat transfer body 20 with this configuration.

[0062] To obtain such a configuration, for example, a plating layer 40 can be formed on the graphite block 11 while the surface of the hole portion 12 is masked. Alternatively, after forming a plating layer 40 that covers the entire graphite block 11, the plating layer 40 on the surface of the hole portion 12 may be removed by blasting or polishing with abrasive paper.

[0063] Alternatively, the plating layer 40 may not be provided on the surface of the side surface 113 of the graphite block 11. With this configuration, heat can be received more effectively on the side surface 113 compared to the case where the plating layer 40 is provided on the side surface 113.

[0064] <Third Embodiment> Next, the configuration of the heat transfer member 1 according to the third embodiment will be described with reference to Figures 5 and 6. Figure 5 is a perspective view showing an example of the configuration of the heat transfer member 1 according to the third embodiment.

[0065] The heat transfer member 1 according to the third embodiment may have a first member 50 and a second member 60 that protect the graphite block 11. That is, the heat transfer member 1 according to the third embodiment corresponds to a configuration in which the first member 50 and the second member 60 are provided in addition to the heat transfer member 1 according to the first embodiment.

[0066] The first member 50 may be, for example, a metal umbrella-shaped member. Specifically, it may be an umbrella-shaped member, for example, having a truncated square pyramidal shape. The first member 50 may be positioned to cover the second surface 112 and side surface 113 of the graphite block 11 which has a truncated cone shape (see Figure 6).

[0067] The second member 60 may be, for example, a thin metal plate. As shown in Figure 5, the dimensions of the second member 60 in plan view may be substantially the same as the dimensions of the first member 50 in plan view. The second member 60 may be positioned to cover the first surface 111 of the graphite block 11 which has a frustoconical shape (see Figure 6). The second member 60 may have a through hole in its center, and the second heat transfer element 20 may be inserted through this through hole.

[0068] Thus, in the heat transfer member 1 according to the third embodiment, the graphite block 11 may be covered by the first member 50 and the second member 60. In other words, the graphite block 11 may be located in the internal space formed by the first member 50 and the second member 60.

[0069] Next, the configuration of the heat transfer member 1 according to the third embodiment will be described in detail with reference to Figure 6. Figure 6 is a cross-sectional view showing an example of the configuration of the heat transfer member 1 according to the third embodiment. Specifically, Figure 6 is a cross-sectional view taken along the line VI-VI shown in Figure 5.

[0070] The first member 50 may have a first inner wall surface 51 that is positioned opposite the second surface 112 of the graphite block 11. The first inner wall surface 51 may be circular in plan view, for example. Specifically, the first inner wall surface 51 may have approximately the same diameter as the second surface 112 of the graphite block 11, for example. The first inner wall surface 51 may be in contact with the second surface 112.

[0071] The first member 50 may be connected to the second heat transfer element 20 at the first inner wall surface 51. For example, the second heat transfer element 20 according to the third embodiment may have a screw groove at one end protruding from the second surface 112. Alternatively, for example, the first member 50 may have a screw hole 511 located on the first inner wall surface 51 that is connected to the screw groove. The first member 50 and the second heat transfer element 20 may be fixedly connected by this configuration.

[0072] In this way, by fixing the first member 50 and the second member 60 together, the first member 50 can directly conduct the heat received from the heat source to the second heat transfer body 20, thereby improving the heat conduction performance of the heat transfer member 1. Furthermore, when the second heat transfer body 20 rotates around the Z axis (θ direction), the first member 50 is less likely to detach from the second heat transfer body 20. Note that the first inner wall surface 51 of the first member 50 and the second member 60 may be joined to each other not only by screws, but also by welding or other means.

[0073] The first member 50 may have a second inner wall surface 52 positioned opposite the side surface 113 of the graphite block 11. This second inner wall surface 52 may be in contact with the side surface 113. Alternatively, the second inner wall surface 52 may be joined to the side surface 113 by a brazing material or the like (not shown).

[0074] With this configuration, the first member 50 and the side surface 113 of the graphite block 11 can be thermally connected. As a result, when the first member 50 receives heat from a heat source, that heat is efficiently conducted to the graphite block 11 via the side surface 113.

[0075] The first member 50 may have a connecting surface 53 that is in contact with the second member 60. This connecting surface 53 may be a plane having an annular shape in plan view. The first member 50 may have a plurality of screw holes 531 located on this connecting surface 53. The second member 60 may also have a plurality of through holes 61, each located opposite the connecting surface 53.

[0076] The first member 50 and the second member 60 may be fixed to each other, for example, by screwing them together. Specifically, for example, the first member 50 and the second member 60 may be fixedly connected by inserting a screw 70 into the through hole 61 and screwing the screw 70 into the screw hole 531. The first member 50 and the second member 60 may be joined to each other by means other than screwing, for example, by welding.

[0077] Thus, according to the heat transfer member 1 of the third embodiment, by covering the graphite block 11 with the first member 50 and the second member 60, the occurrence of peeling or damage to the graphene 13 can be reduced, and the heat transfer member 1 can achieve high toughness. In addition, the diffusion of fragments of the graphite block 11 into the surroundings can be reduced.

[0078] In the third embodiment, the first member 50 is an umbrella-shaped member with a general shape of a truncated square pyramid, but it is not limited to this, and the first member 50 may be an umbrella-shaped member with a general shape of a square pyramid, for example.

[0079] Alternatively, the first member 50 may be a member with a concave shape. In this case, the first member 50 may have at least the first inner wall surface 51, the second inner wall surface 52, and the connecting surface 53 described above.

[0080] Furthermore, the heat transfer member 1 according to the third embodiment can be used, for example, in medical equipment such as CT scanners and X-ray machines, or in rotating anode X-ray tubes in industrial non-destructive testing equipment. In such cases, the first heat transfer element 10 may be a rotating anode.

[0081] In such a case, the rotating anode generates heat due to collisions with accelerated thermionic electrons. In other words, in this case, the rotating anode becomes the heat source. According to the heat transfer member 1 of the third embodiment, the heat generated at the rotating anode can be efficiently transferred to a location away from the heat source. In other words, the thermal conductivity of the rotating anode X-ray tube can be improved.

[0082] Although the present disclosure has been described in detail above, this disclosure is not limited to the embodiments described above, and various modifications and improvements are possible without departing from the gist of this disclosure.

[0083] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. Indeed, the embodiments described above can be embodied in a variety of forms. Furthermore, the embodiments described above may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims.

[0084] Furthermore, this technology can also take the following configurations: (1) A heat transfer member comprising a first heat transfer element and a second heat transfer element, wherein the first heat transfer element comprises a graphite block having a structure in which a plurality of graphenes are stacked, the graphite block has a first surface located at one end in the stacking direction of the graphenes and a hole opening to the first surface, the second heat transfer element is located in the hole and is thermally connected to the graphite block inside the hole, the thermal conductivity of the second heat transfer element is higher than that of the first heat transfer element in the stacking direction, the thermal conductivity of the second heat transfer element is lower than that of the first heat transfer element in a direction perpendicular to the stacking direction, and the side surface of the graphite block is inclined with respect to the stacking direction. (2) The heat transfer member according to (1), wherein the side surface is inclined in a direction in which the dimension of the graphite block in the direction perpendicular to the stacking direction increases toward the first surface. (3) The heat transfer member according to (1) or (2), wherein the hole penetrates the graphite block and the second heat transfer body is located in the internal region of the hole, including the central part of the graphite block in the stacking direction. (4) The heat transfer member according to any one of (1) to (3), wherein the hole opens in the center of the first surface and the second heat transfer body protrudes from the first surface. (5) The heat transfer member according to any one of (1) to (4), wherein the first heat transfer body has a plating layer covering the graphite block. (6) The heat transfer member according to (5), wherein the plating layer covers at least a portion of the graphite block other than the hole. (7) The heat transfer member according to any one of (1) to (6), wherein there is a bonding material between the hole and the second heat transfer body. (8) The graphite block has a frustoconical shape, the hole is open in the center of the first surface and penetrates the graphite block, and the second heat transfer member is the heat transfer member according to any one of (1) to (7) above which penetrates the graphite block.(9) The heat transfer member according to (8), comprising a first member in contact with at least the side surface of the graphite block and a second member in contact with at least the first surface of the graphite block, wherein the graphite block is covered by the first member and the second member. (10) The heat transfer member according to (9), wherein the second heat transfer body is connected to the first member. (11) The heat transfer member according to any one of (1) to (10), wherein in the stacking direction, the thermal expansion coefficient of the first heat transfer body is higher than that of the second heat transfer body. (12) The heat transfer member according to any one of (1) to (11), wherein in a direction perpendicular to the stacking direction, the thermal expansion coefficient of the first heat transfer body is lower than that of the second heat transfer body. (13) The heat transfer member according to any one of (1) to (12), wherein in the stacking direction, the toughness of the first heat transfer body is lower than that of the second heat transfer body. (14) The heat transfer member according to (9) or (10), wherein the absolute value of the difference between the thermal expansion coefficient of the side surface in the direction in which the side surface extends and the thermal expansion coefficient of the first member is smaller than the absolute value of the difference between the thermal expansion coefficient of the graphite block in the stacking direction and the thermal expansion coefficient of the first member.

[0085] 1 Heat transfer member 10 First heat transfer element 11 Graphite block 12 Hole 13 Graphene 20 Second heat transfer element 30 First bonding material 40 Plating layer 50 First member 51 First inner wall surface 52 Second inner wall surface 53 Connecting surface 60 Second member 61 Through hole 70 Screw 111 First surface 112 Second surface 113 Side surface 511, 531 Screw hole

Claims

1. A heat transfer member comprising a first heat transfer element and a second heat transfer element, wherein the first heat transfer element has a graphite block having a structure in which a plurality of graphenes are stacked, the graphite block has a first surface located at one end in the stacking direction of the graphenes and a hole opening to the first surface, the second heat transfer element is located in the hole and is thermally connected to the graphite block inside the hole, the thermal conductivity of the second heat transfer element is higher than that of the first heat transfer element in the stacking direction, the thermal conductivity of the second heat transfer element is lower than that of the first heat transfer element in a direction perpendicular to the stacking direction, and the side surface of the graphite block is inclined with respect to the stacking direction.

2. The heat transfer member according to claim 1, wherein the side surface is inclined in a direction in which the dimension in the direction perpendicular to the stacking direction of the graphite block increases toward the first surface.

3. The heat transfer member according to claim 1 or 2, wherein the hole penetrates the graphite block, and the second heat transfer element is located in the internal region of the hole, including the central portion of the graphite block in the stacking direction.

4. The heat transfer member according to any one of claims 1 to 3, wherein the hole is opened in the center of the first surface, and the second heat transfer element protrudes from the first surface.

5. The heat transfer member according to any one of claims 1 to 4, wherein the first heat transfer body has a plating layer covering the graphite block.

6. The heat transfer member according to claim 5, wherein the plating layer covers at least a portion of the area of ​​the graphite block other than the hole.

7. The heat transfer member according to any one of claims 1 to 6, wherein a bonding material is provided between the hole and the second heat transfer element.

8. The heat transfer member according to any one of claims 1 to 7, wherein the graphite block has a frustoconical shape, the hole opens in the center of the first surface and penetrates the graphite block, and the second heat transfer body penetrates the graphite block.

9. The heat transfer member according to claim 8, comprising a first member in contact with at least the side surface of the graphite block, and a second member in contact with at least the first surface of the graphite block, wherein the graphite block is covered by the first member and the second member.

10. The heat transfer member according to claim 9, wherein the second heat transfer member is connected to the first member.

11. The heat transfer member according to any one of claims 1 to 10, wherein the thermal expansion coefficient of the first heat transfer element is higher than the thermal expansion coefficient of the second heat transfer element in the stacking direction.

12. The heat transfer member according to any one of claims 1 to 11, wherein the thermal expansion coefficient of the first heat transfer element is lower than the thermal expansion coefficient of the second heat transfer element in a direction perpendicular to the stacking direction.

13. The heat transfer member according to any one of claims 1 to 12, wherein the toughness of the first heat transfer element is lower than the toughness of the second heat transfer element in the stacking direction.

14. The heat transfer member according to claim 9 or 10, wherein the absolute value of the difference between the thermal expansion coefficient of the side surface in the direction in which the side surface extends and the thermal expansion coefficient of the first member is smaller than the absolute value of the difference between the thermal expansion coefficient of the graphite block in the stacking direction and the thermal expansion coefficient of the first member.

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