JP5324863B2 - Vacuum furnace and heat treatment apparatus in magnetic field using this vacuum furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum furnace forming a vacuum state during heating by infrared rays while suppressing radiation of heat to outside regardless of the material quality of an outer member and a heat treatment device in the magnetic field using the vacuum furnace. <P>SOLUTION: The vacuum furnace includes an inner pipe 14 formed of a material permeating infrared rays; an outer pipe 16 forming an outer space S2 with the inner pipe 14; a heating means 18 arranged within the outer space S2 and irradiating infrared rays to a heated target W through the inner pipe 14; a holding means 20 for holding the heated target W in the position enabling heating; and a plurality of radiation shield plates 22 arranged within the outer space S2 to shield a space between the heating means 18 and the outer pipe 16 and reflecting the infrared rays from the heating means 18. The respective radiation shield plates 22 are juxtaposed to the direction orthogonal to the inner face of the outer pipe 16 and are arranged so that the adjacent radiation shield plates 22 leave a clearance in their juxtaposed direction. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a vacuum furnace for heating an object to be heated in a vacuum, and a magnetic field heat treatment apparatus using the vacuum furnace.

  Conventionally, as a vacuum furnace for heating an object to be heated in vacuum in order to perform sintering or heat treatment without oxidation, the one described in Patent Document 1 is known.

  As shown in FIG. 3, the vacuum furnace includes a quartz tube 102 that stores a heating object w such as a wafer, a heating furnace 104 that surrounds the quartz tube 102 from the outside, and a heating furnace 104 that surrounds the heating furnace 104 from the outside. And an outer frame 106. The quartz tube 102 is a tube made of quartz and extending vertically. In the quartz tube 102, a first exhaust means (not shown) such as a vacuum pump is connected to an exhaust port 108 provided in the quartz tube 102, and the inside of the quartz tube 102 is evacuated by the first exhaust means. As a result, the internal space s1 becomes a vacuum. The heating furnace 104 is for heating the heating object w stored in the quartz tube 102, and emits infrared rays toward the inside of the heating furnace 104. The outer frame 106 is a box-shaped container made of stainless steel. In the outer frame 106, a second exhaust unit (not shown) is connected to an exhaust port 110 provided in the outer frame 106, and the inside of the outer frame 106 is evacuated by the second exhaust unit, thereby quartz. The outer space s2 formed between the tube 102 and the outer frame 106 is evacuated.

  In the vacuum furnace 100 configured as described above, after the heating object w is stored in the quartz tube 102, the internal space s1 and the external space s2 are respectively formed by the first and second exhaust means (not shown). It is evacuated and becomes a vacuum. After being evacuated in this way, the heating furnace 104 emits infrared rays inward, that is, toward the quartz tube 102. This infrared light is transmitted through the quartz tube 102 and reaches the heating object w. The heating object w is heated by the radiant infrared rays that have reached in this way, whereby the heating object w is heated in vacuum.

At this time, the quartz tube 102 is heated and softened by the heating furnace 104, but both the internal space s1 of the quartz tube 102 and the space around the quartz tube 102 (outer space s2) are in a vacuum, and thus the quartz tube 102 There is only a slight pressure difference between the inside and the outside, and the quartz tube 102 is not deformed by this pressure difference.
Japanese Unexamined Patent Publication No. 6-232065

  In the vacuum furnace 100, it is difficult to select the material of the outer frame 106. For example, when the outer frame 106 is formed of quartz, the outer frame 106 is heated and softened by infrared rays from the heating furnace 104, and a pressure difference between the vacuum outer space s2 and the outside of the outer frame 106 that is atmospheric pressure. There is a risk of deformation. Further, when the outer frame 106 is formed of quartz, it becomes difficult to join the outer frame 106 to another structural material.

  In addition, if the outer frame 106 is made thick in order to prevent heat from infrared rays from the heating furnace 104 from being transferred to the surface of the vacuum furnace 100 (outer frame 106), the structure of the vacuum furnace 100 increases in size. Arise.

  Therefore, in view of the above problems, the present invention provides a vacuum furnace capable of forming a vacuum state under heating by infrared rays while suppressing heat dissipation to the outside regardless of the material of the outer member, and the vacuum It is an object to provide a heat treatment apparatus in a magnetic field using a furnace.

  Therefore, in order to solve the above problems, the vacuum furnace according to the present invention is a vacuum furnace for heating an object to be heated in a vacuum, and is formed of a material that transmits infrared rays and surrounds an evacuable internal space. An outer tube that surrounds the inner tube from the outside to form an outer space that can be exhausted independently of the inner space, and an outer periphery of the inner tube in the outer space A heating unit disposed in a circumferential direction along a surface and irradiating infrared rays to the heating object through the inner tube in order to heat the heating object in the inner tube; and the heating unit in the inner space A holding means for holding the object to be heated at a position where heating is possible, and a plurality of sheets arranged so as to block between the heating means and the outer tube in the outer space and reflecting infrared rays from the heating means Each radiation shield plate Shield plate are aligned in a direction perpendicular to the inner surface of the outer tube, so that the radiation shield plate adjacent places intervals to each other in the arrangement direction, and being disposed respectively. In addition, in this invention, a vacuum means the state decompressed to the pressure close | similar to a vacuum.

  Since the heating means is disposed in the outer space, it is surrounded by the outer tube except in a direction facing the inner tube. Among these, the infrared rays to the inner tube pass through the inner tube and heat the sample inside, while the infrared rays going to the outer tube are reflected by the radiation shield plate, so Is suppressed to the surface of the vacuum furnace. Furthermore, by arranging the plurality of radiation shield plates in the vacuumed outer space, the space required for arranging the radiation shield plates can be reduced.

  Specifically, since the plurality of radiation shield plates are disposed in the outer space, the space between adjacent radiation shield plates is also evacuated by evacuating the outer space. Since heat conduction is low in vacuum, a sufficient heat insulating effect in the direction in which the radiation shield plates are arranged can be obtained even if the thickness of each radiation shield plate and the interval between adjacent radiation shield plates are reduced. Therefore, even if the space between the heating means and the outer tube is narrow in the outer space, it is possible to arrange the radiation shield plates as many as necessary for heat insulation. Therefore, the plurality of radiation shield plates can be disposed in the outer space without greatly increasing the radial size or axial size of the outer tube.

  In the vacuum furnace according to the present invention, it is preferable that the plurality of radiation shield plates are arranged so as to block at least a gap between the heating means and the outer tube in a radial direction of the outer tube.

  According to this configuration, it is possible to reduce the size of the vacuum furnace in the radial direction while suppressing an increase in the surface temperature on the radial side of the vacuum furnace. That is, since the infrared rays going outward in the radial direction from the heating means are reflected by the radiation shield plate, the conduction of heat from the infrared rays to the surface on the radial side in the vacuum furnace is suppressed, and the vacuum The distance between the inner peripheral surface of the outer tube and the heating means can be reduced while suppressing an increase in the surface temperature on the radial side of the furnace.

  The plurality of radiation shield plates are further arranged so as to shield between the heating means and the outer tube also in the axial direction of the outer tube, and the plurality of radiation shield plates arranged in the radial direction. More preferably, the axial end portion and the radially outer end portions of the plurality of radiation shield plates arranged in the axial direction are connected to each other.

  By adopting such a configuration, it is possible to reduce the axial size of the outer tube while suppressing an increase in the surface temperature on the axial direction side of the outer tube, and to conduct heat to the entire surface of the vacuum furnace. Is more suppressed.

  This is because, since infrared rays traveling in the axial direction from the heating means are reflected by the radiation shield plate, conduction of heat from the infrared rays to the surface on the axial direction side in the outer tube is suppressed. This is because the distance between the inner surface on the axial direction side of the outer tube and the heating means can be reduced while suppressing an increase in the surface temperature on the axial direction side of the tube. Further, since the heating means is in a state surrounded by the radiation shield plate except in a direction facing the inner tube, infrared rays that are directed to directions other than the direction toward the inner tube out of the infrared rays irradiated by the heating means are the radiation shield. This is because it is reflected by the plate and the conduction of heat to the surface of the vacuum furnace is further suppressed.

  The inner tube and the outer tube are preferably formed of quartz.

  According to such a configuration, since the inner tube is made of quartz, infrared rays from the heating means are efficiently transmitted into the internal space, and the heating object is efficiently heated by the infrared rays. Further, since the outer tube is formed of quartz like the inner tube, for example, it is not necessary to perform a metallization process like the bonding of quartz and metal, and the outer tube can be easily bonded by welding. It is easy to keep the space airtight.

  Also, a low vacuum pump that exhausts the airtight space from the atmospheric pressure state to a predetermined vacuum level, and a high vacuum that exhausts the space from the predetermined vacuum level to a higher vacuum level. A suction pump of the high vacuum pump is connected to the inner pipe for exhausting the interior space, and the suction part of the low vacuum pump is connected to the inner part via the high vacuum pump. It may be configured to be connected to the exhaust part of the high vacuum pump for exhausting the space and also connected to the outer pipe for exhausting the outside space.

  According to such a configuration, compared to the case where separate exhaust systems are connected to the inner pipe and the outer pipe, the number of pumps for exhausting can be reduced, and the vacuum furnace can be reduced in size and cost. .

  More specifically, the high vacuum pump is a pump that, after roughly exhausting to a predetermined vacuum level with the low vacuum pump, further exhausting from that state to reach a high vacuum level. The exhaust system to be connected requires the low vacuum pump for rough exhaust in addition to the high vacuum pump. Accordingly, the low vacuum pump for rough exhaust in the exhaust system connected to the inner pipe and the low vacuum pump in the exhaust system connected to the outer pipe are used as a common low vacuum pump. Can be reduced.

  A magnetic field heat treatment apparatus according to the present invention is a magnetic field heat treatment apparatus for performing heat treatment of an object to be heated in a strong magnetic field, and is disposed around the vacuum furnace and the vacuum furnace. A superconducting electromagnet that forms a magnetic field in the furnace, and the superconducting electromagnet is disposed around the vacuum furnace so as to apply a magnetic field to the heating object to be heated in the vacuum furnace. A coil and a cryogenic container that holds the superconducting coil while maintaining the superconducting coil at a temperature at which the superconducting coil is in a superconducting state, and in the vacuum furnace, the radiation shield plate is directed from the heating means to the outer tube. It is configured to suppress the influence of heat by the infrared rays into the cryogenic container by reflecting infrared rays.

  According to this configuration, a strong magnetic field can be formed in the internal space while the internal space of the vacuum furnace is in a vacuum state under heating. In addition, for the formation of this strong magnetic field, the influence of heat from the vacuum furnace on the inside of the vessel where the inside must be maintained at a low temperature can be suppressed. That is, by suppressing an increase in the surface temperature of the vacuum furnace, the heat transfer from the vacuum furnace to the container is suppressed, and the vacuum furnace to the superconducting coil held at a low temperature in the container The influence of heat from the can be suppressed. Therefore, even when the vacuum furnace is heated, the superconducting state of the superconducting coil is maintained, and a stable strong magnetic field can be continuously applied to the object to be heated.

  As described above, according to the present invention, a vacuum furnace capable of forming a vacuum state under heating with infrared rays while suppressing heat dissipation to the outside regardless of the material of the outer member, and this vacuum furnace are used. It is possible to provide a heat treatment apparatus in a magnetic field.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

  The heat treatment apparatus in a magnetic field according to the present invention is for performing heat treatment on a heating object while applying a strong magnetic field in a vacuum atmosphere. Applications of such devices include the following.

・ Improved properties of thermoelectric element materials Thermoelectric element materials discovered after 2000 have many oxides, and the crystal structure of these oxides has a layered structure. It is known that the directions are aligned (orientated). It is also known that the material properties of the oxides are improved when the crystal orientations are aligned. However, in order to orient the crystal of the oxide, a magnetic field of 10 T or more that can be generated only with a superconducting magnet is often required. In addition, since the oxide is basically fired into a product, it is necessary that the crystal be oriented in a strong magnetic field and then fired in situ. Therefore, in order to improve the characteristics of the thermoelectric element material such as the oxide, a magnetic field heat treatment apparatus capable of performing heat treatment while simultaneously controlling the magnetic field and the atmosphere (degree of vacuum) is used.

-Improvement of mechanical properties such as alumina, titania, zinc oxide, aluminum nitride, silicon nitride, silicon carbide, apatite These materials are also known to be oriented in a strong magnetic field. For example, apatite used for artificial bone is manufactured by firing raw material powder. At this time, if the crystal direction of the powder is not controlled, the material characteristics are considered to be isotropic. On the other hand, it is known that the crystals of bone in the human body (main component is apatite) are oriented. Therefore, if the raw material powder is oriented and fired in a magnetic field, it can be expected to produce an artificial bone having mechanical properties close to those of real bones. In order to improve the mechanical properties of such materials, a heat treatment apparatus in a magnetic field that can perform orientation and firing in a magnetic field is used.

  In addition to these, attempts have been made at various places to control precipitation in steel materials and non-ferrous metal materials with a magnetic field. In such attempts, the heat treatment apparatus in a magnetic field that can control the atmosphere in the heat treatment process is used. It is done.

  In addition, the heat treatment apparatus in the magnetic field is used in the heat treatment process for semiconductors and the single crystal growth process of silicon where it is important that the atmosphere is vacuum in the heat treatment process. Since a high vacuum environment is required for levitation and the like, the heat treatment apparatus in a magnetic field is used.

  In addition, the vacuum furnace incorporated in the heat processing apparatus in a magnetic field which concerns on this embodiment is not restricted to what is put and used in a magnetic field.

  The magnetic field heat treatment apparatus will be specifically described below. As shown in FIG. 1, the heat treatment apparatus in a magnetic field applies a magnetic field to a sample and a vacuum furnace 10 for heating an object to be heated (hereinafter, also simply referred to as “sample”) W in a vacuum. A superconducting magnet (superconducting electromagnet) 50.

  The vacuum furnace 10 includes a double pipe (vacuum furnace body) 12 and an exhaust system 30 that evacuates (reduces pressure) the double pipe 12. Inside the double tube 12 are a heater (heating means) 18 for heating the sample W, a sample stage (holding means) 20 for holding the sample W, and a plurality of radiation shields for reflecting infrared rays. A plate 22 is arranged.

  The double tube 12 includes an inner tube 14 and an outer tube 16, and an inner space S 1 for arranging the sample W is formed in the inner tube 14, and between the inner tube 14 and the outer tube 16. An outer space S2 for arranging the heater 18 is formed. The inner tube 14 is a tube that surrounds the inner space S1, has a constant diameter, and has one end opening closed. In the present embodiment, the inner tube 14 is a tube that extends vertically and has a closed lower end opening. The inner pipe 14 is configured to be evacuated from the upper opening 15 at the upper end. A flange 15 a that extends in the radial direction of the inner tube 14 is provided around the upper opening 15.

  The outer tube 16 surrounds the inner tube 14 from the outside, that is, a tube having a larger diameter than the inner tube 14, and forms an outer space S <b> 2 between the outer peripheral surface of the inner tube 14 and the inner peripheral surface of the outer tube 16. . Specifically, the outer tube 16 surrounds the outer side of the inner tube 14 so that the inner circumferential surface of the outer tube 16 and the outer circumferential surface of the inner tube 14 are spaced apart from each other. The portion is attached to the inner tube 14 by being joined to the outer peripheral surface of the inner tube 14. An exhaust port 17 is provided at the upper end of the outer pipe 16, and the outer space S <b> 2 can be exhausted from the exhaust port 17 independently of the internal space S <b> 1.

  The inner tube 14 and the outer tube 16 thus configured are each formed of quartz. By doing so, for example, it is not necessary to perform a metallization process like the joining of quartz and metal, the inner tube 14 and the outer tube 16 can be easily joined by welding, and the outer space S2 is made airtight. Easy to keep. However, the material forming the inner tube 14 and the outer tube 16 is not limited to quartz, and is not necessarily limited to the same material.

The exhaust system 30 includes a rotary pump (low vacuum pump) 32 and a turbo molecular pump (high vacuum pump) 34. The rotary pump 32 is a pump for exhausting (depressurizing) the inside space S1 and the outside space S2 from an atmospheric pressure state to a predetermined degree of vacuum (in the present embodiment, about 10 ⁻³ Torr). The turbo molecular pump 34 is a pump for exhausting (depressurizing) the interior space S1 from the predetermined degree of vacuum to a higher degree of vacuum (in this embodiment, about 10 ⁻⁶ Torr).

  In the rotary pump 32 and the turbo molecular pump 34, the intake part 34 a of the turbo molecular pump 34 is connected to the upper opening 15 of the inner pipe 14 via the exhaust pipe 36, and the intake part 32 a of the rotary pump 32 is connected to the exhaust pipe 38. To the exhaust part 34b of the turbo molecular pump 34. The intake portion 32 a of the rotary pump 32 is also connected to the exhaust port portion 17 of the outer tube 16 via the exhaust tube 38. The exhaust pipe 36 and the upper opening 15 of the inner pipe 14 are detachably connected by a flange 36 a provided at the end of the exhaust pipe 36 on the inner pipe 14 side and a flange 15 a of the upper opening 15. . Similarly, the exhaust pipe 38 and the exhaust port 17 of the outer pipe 16 are also detachably connected.

  By configuring the exhaust system 30 in this manner, the number of pumps (rotary pumps 32) for exhausting can be reduced compared to the case where separate exhaust systems are connected to the inner tube 14 and the outer tube 16. That is, the exhaust system to which the turbo molecular pump 34 is connected requires a rotary pump 32 for rough exhaust connected to the exhaust part 34b of the turbo molecular pump 34 in addition to the turbo molecular pump 34. The number of pumps can be reduced by using the rotary pump 32 that is shared with the rotary pump connected to the pipe 16.

  The method of connecting the turbo molecular pump 34 is not limited to the method of connecting to exhaust from one end of the inner pipe 14 as in the present embodiment, but the connection to exhaust from both ends of the inner pipe 14. It may be a method (see FIG. 2A). Separate exhaust systems 30a and 30b may be connected to the inner tube 14 and the outer tube 16 (see FIG. 2B). In this case, since the turbo molecular pump 34 and the rotary pump 32 are arranged in the exhaust system 30a, and the rotary pump 132 different from the exhaust system 30a is arranged in the exhaust system 30b, as in the present embodiment. The number of pumps cannot be reduced.

  The heating heater 18 irradiates the sample W with infrared rays through the inner tube 14 in order to heat the sample W in the inner space S1 of the inner tube 14. The heater 18 is arranged in the circumferential direction along the outer peripheral surface of the inner tube 14 in the outer space S2. In this embodiment, Kanthal or a platinum rhodium alloy is used for the heater 18 for heating. The heater 18 is not limited to Kanthal or a platinum rhodium alloy, and may be made of other materials as long as the sample W can be heated by infrared irradiation.

  The sample stage 20 holds the sample W at a position where it can be heated by the heater 18 in the internal space S1 of the inner tube 14, more specifically, at a position where the heater 18 is disposed in the axial direction of the inner tube 14. To do. Internal radiation shield plates 24 are connected to the sample stage 20 above and below the held sample W via separate members (not shown). The internal radiation shield plate 24 is for reflecting (blocking) the infrared rays traveling in the vertical direction so that the infrared rays applied to the sample W do not go outside from the vertical direction of the inner tube 14. Block to cross. Specifically, a plurality of internal radiation shield plates 24 are arranged in the axial direction of the inner tube 14, and adjacent internal radiation shield plates 24 are arranged so as to be spaced from each other in the arrangement direction (FIG. 1). reference). A spacer 25 is provided between the adjacent internal radiation shield plates 24 in order to maintain the spacing. The sample stage 20 to which such an internal radiation shield plate 24 is connected is inserted into the internal space S1 of the inner tube 14 while holding the sample W. The internal radiation shield plate 24 and the spacer 25 are formed of the same material as the radiation shield plate 22 and the spacer 23 disposed in the outer space S2.

  The radiation shield plate 22 is disposed so as to block between the heater 18 and the outer tube 16 in the outer space S2, and reflects (blocks) infrared rays from the heater 18 toward the outer tube 16. The radiation shield plate 22 is a plate-like body having a constant thickness, the vapor pressure at the temperature at which the sample W is heated is negligibly low, the radiation rate is low, non-magnetic, and resistant to high temperatures ( It has a high melting point and does not soften. In the present embodiment, the radiation shield plate 22 is formed of molybdenum, but is not limited thereto, and may be niobium, tantalum, tungsten, or the like. Moreover, in this embodiment, in order to improve the heat insulation efficiency, the surface of the radiation shield board 22 is comprised so that infrared rays may be reflected.

  The radiation shield plates 22 are arranged so that a plurality of layers form a layer structure. Specifically, the plurality of radiation shield plates 22 are arranged in a direction (left-right direction in FIG. 1) orthogonal to the inner surface of the outer tube 16 on the radial direction side. And each radiation shield board 22 is each arrange | positioned so that it may mutually space in the arrangement direction. Therefore, a layered space is formed between the adjacent radiation shield plates 22. That is, the radiation shield plates 22 and the layered spaces are arranged alternately. In order to form this layered space, a spacer 23 is disposed between adjacent radiation shield plates 22. The spacer 23 is made of a highly heat-insulating material, and ceramics is used in this embodiment. Note that the spacer 23 is not limited to ceramics, and may be formed of molybdenum, niobium, or the like.

  In the plurality of radiation shield plates 22 arranged in this way, the thickness of each radiation shield plate 22 is small and the interval between adjacent radiation shield plates 22 is narrow, but sufficient heat insulation effect in the direction in which the radiation shield plates 22 are arranged is obtained. Can be obtained. This is because the outer space S2 in which the plurality of radiation shield plates 22 are arranged is evacuated when the sample W is heated, so that the heat conduction between the adjacent radiation shield plates 22 becomes low, and the radiation shield plate 22 concerned. This is because is formed of a material having a low emissivity.

  Thus, even if the thickness of the radiation shield plate 22 is reduced and the interval between the adjacent radiation shield plates 22 is reduced, a sufficient heat insulating effect can be obtained. Therefore, in the outer space S2, the heater 18 and the outer tube 16 Even if the interval is narrow, the number of radiation shield plates 22 required for heat insulation can be arranged. Therefore, a plurality of radiation shield plates 22 can be arranged in the outer space S2 without enlarging the size of the outer tube 16 in the radial direction. That is, the vacuum furnace 10 can be downsized.

  The plurality of radiation shield plates 22 are arranged not only on the outside of the heater 18 (on the side opposite to the inner tube 14) but also on the upper side and the lower side so as to block between the heater 18 and the outer tube 16. ing. Specifically, like the radiation shield plate 22 arranged outside the heater 18, a plurality of radiation shield plates 22 are arranged to form a layer structure. The plurality of radiation shield plates 22 are arranged in a direction (vertical direction in FIG. 1) perpendicular to the inner surface on the axial direction side of the outer tube 16 so as to be spaced from each other in the arrangement direction. Therefore, a layered space is formed between the adjacent radiation shield plates 22. In order to form this layered space, a spacer 23 similar to that described above is disposed between adjacent radiation shield plates 22.

  The radiation shield plate 22 disposed above and below is connected to the end of the outer tube 16 in the radial direction on the axial end of the outer tube 16 of the radiation shield plate 22 disposed outside the heater 18 for heating. Yes. Specifically, in this connection part, a plurality of radiation shield plates 22 arranged outside the heater 18 and a plurality of radiation shield plates 22 arranged on the upper side (or lower side) are both layered. The radiation shield plates 22 of the corresponding layers are connected to each other.

  By arranging the radiation shield plate 22 in this way, a plurality of radiation shield plates 22 can be arranged in the outer space S2 without increasing the size of the outer tube 16 in the axial direction. In addition, infrared rays that are directed to directions other than the direction toward the inside of the inner tube 14 among the infrared rays irradiated by the heater 18 are reflected by the radiation shield plate 22 and cannot reach the outer tube 16. The plurality of radiation shield plates 22 do not have to be disposed in the vicinity of the inner peripheral surface of the outer tube 16 or the heater 18, and are disposed so as to block between the outer tube 16 and the heater 18. If it is, it may be arranged at a position away from both the outer tube 16 and the heater 18.

  The superconducting magnet 50 is for forming a magnetic field in the vacuum furnace. Specifically, the superconducting magnet 50 includes a superconducting coil 52 for forming the magnetic field, and a cryostat (cold container) 54 that accommodates the superconducting coil 52 while maintaining the superconducting coil 52 at a temperature at which it is in a superconducting state. .

  The cryostat 54 is a vacuum container in which a storage space S3 for storing the superconducting coil 52 is formed and the storage space S3 is evacuated. The cryostat 54 has a cylindrical appearance with a large interval between the inner peripheral surface 54a and the outer peripheral surface 54b, and the vacuum furnace 10 is disposed in a region surrounded by the inner peripheral surface 54a along the central axis.

  The superconducting coil 52 is a solenoid coil that is housed in the housing space S3 of the cryostat 54 and shares a central axis with the vacuum furnace 10. The superconducting coil 52 is formed by winding a superconducting wire around a winding frame (not shown) made of aluminum or SUS. In this embodiment, the superconducting wire is made of NbTi and / or Nb3Sn.

  Around the superconducting coil 52, a heat shield 56 is provided for suppressing the influence of heat from the outside on the superconducting coil 52 and assisting cooling of the superconducting coil 52. The heat shield 56 is formed of a material having a high emissivity, and high-purity aluminum is used in the present embodiment.

  A cryogenic refrigerator 58 is connected to the superconducting coil 52 and the heat shield 56. The cryogenic refrigerator 58 is for cooling the superconducting coil 52 and the heat shield 56 so that the superconducting coil 52 can maintain a superconducting state.

  In the magnetic field heat treatment apparatus configured as described above, the heat treatment of the sample W in the magnetic field is performed as follows.

  The sample stage 20 is held by the sample stage 20, and the sample stage 20 holding the sample W is inserted into the internal space S1 from the upper opening 15 of the inner tube. At this time, the upper opening 15 of the inner pipe 14 and the exhaust pipe 36 are removed. Then, after the sample stage 20 is inserted into the inner tube 14, the flanges 15a, 36a of the upper opening 15 of the inner tube 14 and the exhaust tube 36 are connected by bolts or the like.

  In this state, the rotary pump 32 is operated, and the inside of the outer space S2 is exhausted and depressurized. Further, the rotary pump 32 exhausts the internal space S1 of the inner pipe 14 via the turbo molecular pump 34 and depressurizes it, because the intake part 32a is also connected to the exhaust part 34b of the turbo molecular pump 34. In this way, the internal space S1 and the outer space S2 are depressurized to a predetermined degree of vacuum by the common rotary pump 32.

When the inside space S1 and the outside space S2 reach a predetermined degree of vacuum, the turbo molecular pump 34 operates to depressurize the inside space S1 to a high vacuum state with a higher degree of vacuum. In the present embodiment, the pressure is reduced (evacuated) so that the outer space S2 is 10 ⁻³ Torr and the inner space S1 is 10 ⁻⁵ Torr.

  On the other hand, the superconducting magnet 50 is operated to form a uniform magnetic field (strong magnetic field) in the region where the sample W is held in the internal space S1. At this time, in order to maintain the superconducting state of the superconducting coil 52 and stably form the magnetic field, the superconducting coil 52 is housed in the cryostat 54 at an extremely low temperature. In the present embodiment, a magnetic field (about 10T in the present embodiment) is formed in which the magnetic field lines are perpendicular and the magnetic field strength is uniform. By forming such a magnetic field, a magnetic field is applied to the sample W.

  In this way, the heater 18 is operated in a state where the internal space S1 and the outer space S2 are depressurized to a predetermined degree of vacuum and a magnetic field is applied to the sample W. Infrared radiation emitted from the heater 18 passes through the inner tube 14 and reaches the sample W. The sample W is heated by the infrared rays (radiant infrared rays) that have arrived in this manner, whereby the sample W to which a magnetic field has been applied in a vacuum is heated. In the present embodiment, the sample W is heat-treated at 1000 ° C. or higher.

  On the other hand, of the infrared rays irradiated by the heater 18, the infrared rays that have not been directed to the sample W due to reflection on the outer peripheral surface of the inner tube 14 go to the outer tube 16. The infrared rays toward the outer tube 16 are reflected by the radiation shield plate 22. That is, the infrared rays that are directed toward the outer tube 16 without being directed toward the sample W are reflected by the radiation shield plate 22 disposed so as to block between the heater 18 and the outer tube 16, and cannot reach the outer tube 16.

  In addition, when reflected by the radiation shield plate 22, a part of the infrared energy is absorbed as heat, and this heat passes through the radiation shield plate 22 and is emitted from the back surface (the surface opposite to the side where the infrared light is incident). Is done. And the heat which reached | attained the adjacent radiation shield board 22 passes through this radiation shield board 22, and is discharge | released from a back surface. The above process is repeated, and the heat absorbed by the radiation shield plate 22 during the reflection attempts to pass through the plurality of radiation shield plates 22 in the arrangement direction, but the outer space S2 is evacuated. The heat cannot pass through the plurality of radiation shield plates 22, or can pass through very little.

  This is because, since the outer space S2 is in a vacuum state, the heat released from the back surface of the radiation shield plate 22 can only move as radiant infrared rays, so that the heat conduction between the radiation shield plates 22 is low, and the radiation shield plate. Since 22 is made of a material having a low emissivity, the intensity of the infrared rays radiated from the back surface is small with respect to the incident infrared rays. Therefore, the plurality of radiation shield plates 22 have sufficient heat insulation in the arrangement direction. This is because an effect can be obtained.

  With such a plurality of radiation shield plates 22, heat from the infrared rays from the heater 18 cannot reach the outer tube 16 or only a little, so that the surface temperature of the outer tube 16 due to heating by infrared rays, that is, An increase in the surface temperature of the vacuum furnace 10 is suppressed.

  On the other hand, in the inner tube 14, since the infrared rays directed toward the sample W pass through the tube wall of the inner tube 14 and reach the sample W as described above, the portion where the infrared rays are transmitted is heated.

  At this time, since the inner tube 14 is made of quartz, the heated portion of the inner tube 14 is softened, but the deformation of the softened portion is suppressed by the outer tube 16. That is, in the portion softened by heating in the inner tube 14, the outer space S <b> 2 surrounded by the outer tube 16 is formed on the outer side in the radial direction of the inner tube 14. Deformation due to a pressure difference from the evacuated internal space S1 does not occur. Furthermore, since the outer space S2 is also evacuated, the pressure difference between the outer space S2 and the inner space S1 is small in the softened portion, and deformation due to the pressure difference does not occur in the softened portion. Further, since the outer tube 16 is not heated and does not soften and is joined to the inner tube 14 at the upper and lower sides with the softened portion of the inner tube 14 interposed therebetween, the inner tube 14 is supported to suppress deformation.

  Further, since the inner tube 14 is formed of quartz, the gas permeability of the portion of the inner tube 14 heated by the heater 18 is increased, but from the portion where the gas permeability is increased by the outer tube 16. Permeation of outside air into the inner pipe 14 is suppressed. That is, an outer space S2 surrounded by the outer tube 16 is formed on the outer side in the radial direction of the inner tube 14 at the portion where the gas permeability is increased by heating, and this outer space is evacuated. The air or the like does not enter the internal space S1 from the part where the gas permeability is increased, and the degree of vacuum of the internal space S1 is not lowered. In other words, even when the inner tube 14 is made of quartz, the vacuum outside space S2 is provided by the outer tube 16, so that it is easy to maintain the degree of vacuum in the inner tube 14 during heating.

  By using the vacuum furnace 10 as described above, that is, the vacuum furnace 10 that can suppress an increase in the temperature of the surface during heating, in the heat treatment apparatus in a magnetic field according to the present embodiment, the internal space S1 of the vacuum furnace 10 is reduced. A strong magnetic field can be formed in the internal space S1 while being in a vacuum state under heating. In addition, for the formation of this strong magnetic field, the influence of heat from the vacuum furnace 10 into the cryostat 54 whose interior must be kept at a low temperature can be suppressed. That is, by suppressing the increase in the surface temperature of the vacuum furnace 10, the heat transfer from the vacuum furnace 10 to the cryostat 54 is suppressed, and the vacuum furnace 10 to the superconducting coil 52 held at a low temperature in the cryostat 54. The influence of heat from the can be suppressed. Therefore, even when the vacuum furnace 10 is heated, the superconducting state of the superconducting coil 52 is maintained, and a stable magnetic field can be continuously applied to the sample W.

  In addition, the heat processing apparatus in a magnetic field of this invention is not limited to the said embodiment, Of course, a various change can be added in the range which does not deviate from the summary of this invention.

  For example, in the present embodiment, the magnetic field formed in the part where the sample W of the vacuum furnace 10 is held is a magnetic field in which the magnetic lines of force are directed in the vertical direction, but is not limited thereto, and in the part, the horizontal direction The superconducting coil 52 may be disposed so that the magnetic field is applied to the cusp magnetic field, and the superconducting coil 52 may be disposed such that the central region of the cusp magnetic field is the portion.

  Moreover, although the double tube 12 extended up and down is used for the vacuum furnace 10 in this embodiment, the structure extended in a horizontal direction may be sufficient.

The schematic block diagram of the heat processing apparatus in a magnetic field which concerns on this embodiment is shown. It is a vacuum furnace which concerns on other embodiment, Comprising: (a) shows the schematic block diagram of the vacuum furnace by which the separate exhaust system was connected to the inner pipe and the outer pipe, respectively, (b) is the both ends of an inner pipe The schematic block diagram of the vacuum furnace to which the exhaust system exhausted from is connected is shown. The schematic block diagram of the conventional vacuum furnace is shown.

Explanation of symbols

10 Vacuum furnace 14 Inner tube 16 Outer tube 18 Heating heater (heating means)
20 Sample stage (holding means)
22 Radiation shield plate 50 Superconducting magnet (superconducting electromagnet)
52 Superconducting coil 54 Cryostat S1 Internal space S2 Outer space W Sample (object to be heated)

Claims (6)

A vacuum furnace for heating an object to be heated in vacuum,
An inner tube that is formed of a material that transmits infrared rays and surrounds an internal space that can be exhausted;
By surrounding the inner tube from the outside, an outer tube that forms an outer space that can be exhausted independently of the inner space between the inner tube and the inner tube;
A heating means that is arranged in the outer space along the outer peripheral surface of the inner tube in the circumferential direction, and irradiates the heating object with infrared rays through the inner tube in order to heat the heating object in the inner tube. When,
Holding means for holding the object to be heated in a position that can be heated by the heating means in the internal space;
A plurality of radiation shield plates that are arranged so as to shield between the heating means and the outer tube in the outer space, and that reflect infrared rays from the heating means;
Each of the radiation shield plates is arranged in a direction orthogonal to the inner surface of the outer tube, and the adjacent radiation shield plates are arranged so as to be spaced from each other in the arrangement direction. In the vacuum furnace according to claim 1,
The vacuum furnace, wherein the plurality of radiation shield plates are arranged so as to shield between the heating means and the outer tube in a radial direction of the outer tube. The vacuum furnace according to claim 2,
The plurality of radiation shield plates are arranged so as to block between the heating means and the outer tube also in the axial direction of the outer tube,
The axial ends of the plurality of radiation shield plates arranged in the radial direction and the radially outer ends of the plurality of radiation shield plates arranged in the axial direction are connected to each other. A vacuum furnace characterized by The vacuum furnace according to any one of claims 1 to 3,
The vacuum furnace, wherein the inner tube and the outer tube are each formed of quartz. In the vacuum furnace according to any one of claims 1 to 4,
A low vacuum pump that exhausts air in an airtight space from atmospheric pressure to a predetermined vacuum,
A high vacuum pump that evacuates the space from the predetermined vacuum level to a higher vacuum level.
An intake portion of the high vacuum pump is connected to the inner pipe for exhausting the interior space, and an intake portion of the low vacuum pump exhausts the interior space via the high vacuum pump. The vacuum furnace is connected to the exhaust part of the high vacuum pump and also connected to the outer pipe for exhausting the outside space. A heat treatment apparatus in a magnetic field that heats an object to be heated in a strong magnetic field,
The vacuum furnace according to any one of claims 1 to 5,
A superconducting electromagnet disposed around the vacuum furnace and forming a magnetic field in the vacuum furnace;
The superconducting electromagnet includes a superconducting coil disposed around the vacuum furnace so as to apply a magnetic field to the heating object heated in the vacuum furnace, and the superconducting coil is superposed on the superconducting coil. Having a cryogenic container to be accommodated while maintaining a temperature at which the conductive state is achieved,
The vacuum furnace is configured to suppress the influence of heat by the infrared rays into the cryogenic container by reflecting the infrared rays from the heating means to the outer tube by a radiation shield plate. Medium heat treatment equipment.

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