JPH10185339A - Cryogenic cold storage material, refrigerating machine employing the same and heat shielding material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the pressure loss of refrigerant (operating medium) to develop refrigerating capacity sufficiently and permit the restraining of invasion of heat effectively by a method wherein the cavities of a porous bearer are filled with magnetic granular bodies, containing rare earth elements, in a cryogenic heat storage material employed for refrigerating machine and the like. SOLUTION: A sheet type cryogenic cold storage material 1 is provided with the structure of organization, in which the cavities of a porous bearer 2, made of Ni, are filled with a multitude of magnetic granular bodies (ErNi alloy powder). Respective magnetic granular bodies 4 are connected strongly to the porous bearer 2 through a connecting agent or polyvinyl alcohol. On the other hand, bumps, having the height of about 0.05mm, are formed on the surface of the cryogenic heat storage material 1 through rolling work employing an emboss working roll. The ends of obtained respective cryogenic cold storage materials 1 are connected by welding to make a continuous ribbon type cold heat storage material while the cold heat storage material is rolled to obtain a rolled cryogenic cold storage material 1. The roll type cryogenic cold storage material 1 is filled into the cold storage device 5 to effect cold storage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryogenic cold storage material used in refrigerators and the like, a refrigerator using the same, and a cryogenic heat shield material. The present invention relates to a cryogenic cold storage material that can be easily processed into a shape that reduces pressure loss and that can exhibit a low pressure loss, a refrigerator using the same, and a cryogenic heat shield material.

[0002]

2. Description of the Related Art In recent years, superconducting technology has been remarkably developed, and as its application field has expanded, the development of a small, high-performance refrigerator has become indispensable. Such refrigerators are required to be lightweight, small, and have high thermal efficiency.

For example, in a superconducting MRI apparatus, a cryopump, or the like, a refrigerator using a refrigeration cycle such as a Gifford-McMahon system (GM system) or a Stirling system is used. High-performance refrigerators are also essential for magnetic levitation trains. More recently, a high-performance refrigerator has been equipped as a main component in a superconducting power storage device (SMES), a single crystal pulling device in a magnetic field for producing high quality silicon wafers, and the like. Further, in order to stabilize the temperature of components operating in a cryogenic region, such as superconducting wires, superconducting elements, and infrared sensors, cryogenic cold storage materials for thermal anchors, heat sinks, and heat shields are widely used.

FIG. 9 is a cross-sectional view showing a main part of a conventional two-stage GM refrigerator. The GM refrigerator 10 has a vacuum vessel 13 in which a large-diameter first cylinder 11 and a small-diameter second cylinder 12 connected coaxially with the first cylinder 11 are installed. A first regenerator 14 is disposed in the first cylinder 11 so as to reciprocate freely.
2 is provided with a second regenerator 15 reciprocally movable.
Between the first cylinder 11 and the first regenerator 14;
Seal rings 16 and 17 are arranged between the cylinder 12 and the second regenerator 15, respectively.

The first regenerator 14 contains a first regenerative material 18 such as a Cu mesh. In the second regenerator 15,
A cryogenic cold storage material is accommodated as the second cold storage material 19. The first regenerator 14 and the second regenerator 15 are provided in a space between the first regenerator 18 and the cryogenic regenerator 19 and the like.
Each has a passage for a working medium (refrigerant) such as gas.

A first expansion chamber 20 is provided between the first regenerator 14 and the second regenerator 15. Further, a second expansion chamber 21 is provided between the second regenerator 15 and the end wall of the second cylinder 12. A first cooling stage 22 is provided at the bottom of the first expansion chamber 20, and a second expansion chamber 21
A second cooling stage 23 having a lower temperature than the first cooling stage 22 is formed at the bottom of the first cooling stage 22.

In the two-stage GM refrigerator 10 described above, a high-pressure working medium (for example, He
Gas) is supplied. The supplied working medium passes between the first regenerators 18 accommodated in the first regenerator 14, reaches the first expansion chamber 20, and further reaches the cryogenic regenerator material accommodated in the second regenerator 15. (Second regenerative material) passes through the space 19 and reaches the second expansion chamber 21. At this time, the working medium is each cold storage material 1
8 and 19 are cooled by supplying thermal energy. The working medium that has passed between the cold storage materials 18 and 19 is
21 to generate cold, and each cooling stage 22,
23 is cooled. The expanded working medium is stored in each cold storage material 1
It flows between 8 and 19 in the opposite direction. The working medium is each cold storage material 1
Emitted after receiving thermal energy from 8,19. As the recuperation effect becomes better in such a process, the thermal efficiency of the working medium cycle is improved, and a lower temperature is realized.

That is, in the GM refrigerator as described above, the inside of the regenerator filled with the regenerator material is compressed He
A working medium, such as a gas, flows in one direction and supplies its thermal energy to the cold storage material, where the expanded working medium flows in the opposite direction and receives heat energy from the cold storage material. As the recuperation effect becomes better in such a process, the thermal efficiency of the working medium cycle is improved and a lower temperature can be realized.

Conventionally, Cu, Pb, and the like have been mainly used as the cold storage material used in the refrigerator described above.
However, since such a regenerator material has a remarkably small volume specific heat in an extremely low temperature range of 20 ° K or less, the recuperation effect described above does not function sufficiently, and it has been difficult to realize an extremely low temperature.

Therefore, recently, in order to realize a temperature closer to absolute zero, Er ₃ Ni, ErNi, ErNi ₂ , ErRh, which show a large volume specific heat in a cryogenic temperature region, have been developed.
Use of a magnetic regenerator made of an intermetallic compound composed of a rare earth element and a transition metal element, such as HoCu ₂ , has been studied.

The above-described magnetic regenerator material is usually processed into a spherical shape having a diameter of about 0.1 to 0.5 mm in order to efficiently perform heat exchange with a working medium such as He gas. Used in body shape. By applying the regenerator filled with the spherical magnetic particles to a GM refrigerator, a refrigeration operation in which the ultimate temperature is 4 ° K is realized.

FIG. 10 is a sectional view showing an example of the configuration of a low-temperature cold storage device 30 using the GN refrigerator 10 as described above. In particular, a superconducting MRI device, a magnetic levitation train, a superconductive power storage device (SMES), 1 shows a superconducting magnet cooler constituting a main part such as a single crystal pulling apparatus.

A low-temperature cooling device 30 shown in FIG. 10 is disposed so as to surround a superconducting magnet 31 as an object to be cooled, a GM refrigerator 10 for cooling the superconducting magnet 31 to an extremely low temperature, and a superconducting magnet 31. The plurality of heat shield materials 32 are arranged in a vacuum vessel 33. The plurality of heat shield members 32 are held in a vacuum vessel 33 via support members 34. A thermal switch 35 for thermally separating the cooling means such as the refrigerator 10 from the cooled object.
Is provided.

The heat shield 32 has a thickness of 1 to 1.
Those made of a copper (Cu) plate of about 2 mm are widely used. In order to suppress heat intrusion from the outside as much as possible and to increase the cooling efficiency of the entire cooling system, these heat shielding materials 3 are used.
2 are arranged in multiple layers.

[0015]

However, unlike a conventional GM refrigerator having a refrigeration cycle as low as about several Hz as described above, such as a Stirling refrigerator or a pulse tube refrigerator having a refrigeration cycle of several tens Hz, as described above. In a refrigerator that performs high-speed cycle operation, the pressure loss in the regenerator filled with the spherical magnetic particles increases, and heat exchange between the working medium and the magnetic particles becomes insufficient. There was a problem that it was difficult to exert the refrigerating ability.

On the other hand, as a countermeasure for reducing the pressure loss in the regenerator, the shape of the magnetic regenerator material is a punched plate or ribbon-shaped regenerator material having a large number of through-holes wound in a roll shape, a mesh. A method has also been tried in which a cold storage material is processed into a laminated screen in which a plurality of cold storage materials are laminated.

However, since the magnetic regenerator material has remarkable brittleness peculiar to an intermetallic compound, it is difficult to perform a drilling process and a bending process, and it is substantially impossible to reduce the pressure loss in the regenerator by the shape of the regenerator material. Was impossible.

On the other hand, in a conventional low-temperature cooling device using a copper heat shielding material, when the refrigerator is stopped or when a low-temperature liquefied gas such as helium (He) evaporates, the specific heat of copper at a low temperature is reduced. Is small, the temperature of the heat shield material rises in a short time, and there is a problem that the effect of suppressing heat intrusion from the outside is lost.

Recently, a system for operating a cooling object such as a superconducting magnet in a compact operating state by separating the cooling means from the cooled object once has been studied. However, a conventional heat shield material made of only a metal material such as copper has a low specific heat and therefore has a small cooling effect, which makes it difficult to maintain a cooled object at a low temperature for a long time. there were.

As a countermeasure, a magnetic regenerator material made of an intermetallic compound containing a rare earth element and a transition metal element such as Er ₃ Ni, ErNi, HoCu ₂ , which has a large specific heat particularly in an extremely low temperature region, is used as a material of the heat shield material. The inventors of the present application have thought that this will be done. However, since the magnetic regenerative material as described above is generally a brittle material, there has been a problem that it is extremely difficult to process the magnetic regenerative material into a sheet material having a size used for a heat shield material.

For an object to be cooled such as a superconducting coil, a cylindrical heat shield material as shown in FIG. 10 is preferable, but a magnetic regenerator material, which is a brittle material, is formed into a cylindrical or curved surface. There is a problem that processing is more difficult than the flat shape.

On the other hand, the magnetic regenerator made of a rare earth element such as Nd has a slightly lower specific heat characteristic than the magnetic regenerator made of the above-mentioned intermetallic compound. In addition, it has a relatively large specific heat in an extremely low temperature region as compared with a normal metal such as Cu, and can be processed into a plate shape. However, in general, the heat shield material is often used in a relatively large area shape, and is used under the condition that a large load acts on the heat shield material itself. However, the structural strength of a heat shield material composed of a single element of a rare earth element such as Nd was insufficient, and it was impossible to apply the heat shield material as it was.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. In particular, the present invention is directed to processing a refrigerant (operating medium) into a shape having a small pressure loss and sufficient refrigeration capacity and a low pressure loss. It is a first object of the present invention to provide an extremely low-temperature regenerator material that can be easily operated and a refrigerator using the same.

It is a second object of the present invention to provide a heat shield material which can effectively suppress heat penetration, can be easily processed into an arbitrary shape, and has excellent structural strength. .

[0025]

In order to achieve the above object, a cryogenic cold storage material according to the present invention comprises a magnetic carrier containing a rare earth element filled in pores of a porous carrier. It is characterized by. Further, the porous carrier may be made of a sheet-like porous metal or a mesh-like metal. Further, the porosity of the porous carrier is preferably 90% or more. The porous carrier is preferably made of a foamed metal. further,
The porous carrier may be formed in a sheet shape, and a plurality of protrusions may be formed on at least one surface of the porous carrier.

Further, the cold storage material for cryogenic use according to the present invention prepares a uniform slurry by mixing magnetic particles containing a rare earth element with a binder, a solvent, a dispersant and a plasticizer.
The magnetic particles may be joined to each other by forming the obtained slurry into a sheet. Further, it is preferable to form a large number of ventilation holes in the sheet-shaped molded body made of the magnetic particles.

[0027] The refrigerator according to the present invention is characterized by comprising a regenerator filled with a cryogenic regenerator material formed by filling the pores of a porous carrier with the magnetic particles containing the rare earth element. And

Further, the cold storage material for cryogenic use formed in the sheet shape may be filled in a cold storage device in a state of being wound in a roll shape. Further, the cold storage material for cryogenic temperature may be composed of a plate-shaped cold storage material element having a large number of ventilation holes, and the plurality of cold storage material elements may be filled in a state of being stacked in multiple stages in the axial direction of the regenerator.

The cryogenic heat shield material according to the present invention is characterized in that the cryogenic cold storage material prepared as described above is integrally joined to a reinforcing member made of a material different from the cryogenic cold storage material. And

The reinforcing member is preferably made of at least one metal material selected from Cu, Al, Fe, and Ni or an alloy containing the metal material as a main component. The cryogenic cold storage material is characterized in that it is a sheet-shaped cold storage material formed by filling the pores of the porous carrier with magnetic particles together with a binder. Further, the cold storage material for cryogenic temperature and the reinforcing member may be joined by the binder.

As the magnetic particles used in the present invention, for example,

Formula 1: RM _z (1) (where R is Y, La, Ce, Pr, Nd, Pm, S
at least one rare earth element selected from m, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb;
M represents at least one metal element selected from Ni, Co, Cu, Ag, Al, Ru, In and Rh;
Represents a number in the range of 0.001 to 9.0 in atomic ratio. The same shall apply hereinafter), an intermetallic compound containing a rare earth element,
Magnetic particles made of a single element of a rare earth element such as Nd can be used.

The magnetic particles can be prepared by mechanically pulverizing a mother alloy having a predetermined composition. Further, a metal melt containing a predetermined amount of a rare earth element or a rare earth element melt is processed by a melt quenching method such as a centrifugal spray method, a rotating disk method (RDP method), an inert gas atomizing method, a single roll method, and a twin roll method. It can also be prepared. The shape of the magnetic particles may be any shape such as an irregular shape or a spherical shape.

When the particle size of the magnetic particles exceeds 5 mm, the filling of the porous carrier is impaired. Therefore, the particle size of the magnetic particles is set to 5 mm or less, but a more preferable particle size is 1 mm.
mm or less, but a more preferred particle size range is 0.1 mm.
It is 2 mm or less.

As the porous carrier for filling the magnetic particles, Ni, Cu, Pb, F which is excellent in workability and inexpensive is used.
e, stainless steel, Ni alloy, Cu alloy, Pb alloy, F
Those formed of an e-alloy are preferred. Further, a body in which a plating layer of Cr or the like is formed on the surface of a main body made of these metals or alloys can be used.

Specific examples of the porous carrier include a porous metal such as a foamed metal, and a mesh metal formed by weaving a metal wire vertically and horizontally.

The above-mentioned porous carrier can be produced, for example, according to the following steps. That is, after conducting a conductive treatment to a foamed resin such as urethane in which open cells are formed, various metal components such as Ni, Ni—Cr, and Ni—Al are electroplated on the inner and outer surfaces of the foamed resin. By volatilizing the components and performing alloying at the same time,
A porous metal-like carrier material in which the resin portion is voided is obtained. This carrier material is processed into a sheet or block shape to obtain a porous carrier used in the present invention.

The porosity of the porous carrier is more preferably larger from the viewpoint of filling a larger amount of magnetic particles having a large volume specific heat in an extremely low temperature range. The porosity of the porous carrier is preferably 20 vol.% Or more, more preferably 60 vol.
l.% or more, more preferably 90 vol.% or more. The porosity of the porous carrier is controlled to be 10 to 98 by controlling the degree of foaming of the foamed resin in the production process.
It can be adjusted arbitrarily within the range of vol.%.

The porous carrier prepared as described above can be filled with a large amount of magnetic particles in proportion to an increase in porosity. In addition, since it has a high specific surface area and all pores communicate with each other, the airflow resistance is small and the pressure loss is also small.

The cold storage material for cryogenic use according to the present invention is formed by filling the pores of the porous carrier prepared as described above with magnetic particles. Heat exchange between the working medium and the cold storage material
When the working medium passing through the inside of the sheet-shaped regenerator is used in a regenerator designed to directly exchange heat with the regenerator, the ratio of filling the porous particles with the magnetic particles is 20 to 20.
90%. When the filling ratio is less than 20%, the flow path (ventilation) resistance of the working medium is small, but the cooling effect of the magnetic particles is insufficient. On the other hand, if the filling ratio exceeds 90%, the flow resistance of the working medium becomes excessively large, so that the pressure loss of the regenerator becomes large and the regenerative effect is reduced.

Here, the filling ratio is defined as the magnetic cold storage material particles occupying the whole volume (including the porous carrier) of the sheet-shaped cold storage material whose thickness has been finally adjusted by a roll process as described later. Defined as a percentage of body volume.

Further, the heat exchange between the working medium and the cold storage material is mainly performed by the working fluid passing through the surface of the sheet cold storage material having a low flow path resistance, not by the working medium passing through the inside of the sheet cold storage material. When used in a regenerator (gap regenerator) designed to exchange heat with a regenerator material, the filling ratio of the magnetic particles is in the range of 60 to 92%. In addition, 65-8
A range of 8% is preferable, and a range of 70 to 85% is more preferable. When the filling ratio is small, the cold storage effect of the magnetic particles is reduced. On the other hand, when the filling ratio is too large, the magnetic particles are distorted due to stress applied at the time of filling and the characteristics are deteriorated.

By attaching a thermoplastic resin such as polyvinyl alcohol (PVA) or a thermosetting resin such as epoxy resin or polyimide as a binder to the surface of the porous carrier or the surface of the magnetic particles, The bonding strength between the body and the porous carrier can be increased, the magnetic particles are less likely to fall off due to vibration or the like, and a cryogenic cold storage material having excellent structural strength can be obtained.

As a method of filling the porous carrier with the magnetic particles to form a composite, for example, a binder and a solvent are mixed with the magnetic particles prepared by the above-mentioned melt quenching method or mechanical pulverization method. A slurry-like paste was prepared, and the paste was uniformly filled in a porous carrier such as a porous metal or a mesh-like metal prepared as described above. A method of drying for 5 to 2.0 hours to remove the solvent component can be adopted.

The bonding strength between the magnetic particles and the porous carrier can be increased by further pressing or rolling the porous carrier filled with the magnetic particles (powder). At the same time, it becomes possible to adjust the thickness of the cold storage material for cryogenic temperature formed in a sheet shape.

The thickness of the sheet-like cold storage material for cryogenic temperature is as follows:
The range is 0.01 to 2 mm in order to secure the ease of winding or bending to form a predetermined shape. Note that 0.
The thickness is preferably in the range of 0.5 to 1.0 mm, more preferably 0.1 to 1.0 mm.
The range of about 0.5 mm is more preferable.

A plurality of projections are formed on the surface of the porous carrier by rolling the porous carrier filled with the magnetic particles into a sheet shape using an embossing roll having irregularities on the surface. can do. When the porous carrier having the projections is wound to form a columnar cold storage material for cryogenic use, the adjacent sheet-shaped porous carriers are not closely adhered to each other and are isolated from each other by the projections. Therefore, when applied to the gap regenerator, a working medium (refrigerant) such as He gas can smoothly flow through the space of the isolation part, and the pressure loss of the working medium becomes extremely small.

[0047] As a further transition metal or various alloys which is a constituent material of the porous carrier such as the porous metal or meshed metal, heat in the low temperature region in comparison with the particular magnetic cold accumulating material made of the general formula RM _z High conductivity can be selected. In this way, the Stirling refrigerator or pulse tube refrigerator that performs a high-speed cycle operation such that the heat penetration depth is reduced is provided with the cryogenic cold storage material of the present application comprising the porous carrier and the magnetic particles. Even when is used, the heat transfer effect of the porous metal or mesh-like metal is sufficiently exerted on the magnetic particles filled in the deep portion of the porous carrier, and the magnetic particles, the carrier, and the working medium The heat exchange between the two is performed quickly.

On the other hand, depending on the design of the regenerator, it may be desired to reduce the heat conduction from the high-temperature side to the low-temperature side of the regenerator.
In such a case, it is preferable to use a material having a low thermal conductivity in a low-temperature region, such as stainless steel, in contrast to the above, for example, as a transition metal or various alloys to be a constituent material of the porous carrier. . Such a choice can be either a refrigerator or a regenerator design.

When the porous carrier filled with the magnetic particles is loaded into a regenerator, it may be wound into a roll or a sheet cut into an appropriate shape. In the case of processing into a roll, it is also possible to stack a plurality of narrow pieces and load them in the regenerator. When a sheet-like material is used, it is conceivable that the flat surface is loaded substantially parallel to the flow direction of the working medium, or that the flat surface is loaded so as to be orthogonal thereto. In the case of orthogonal loading, in order to secure a flow path for the working medium, it is necessary to perform perforation or use a magnetic particle having a low packing density.

According to the cold storage material for cryogenic temperature according to the above configuration,
A porous carrier with low airflow resistance and good workability is formed by filling magnetic particles in the pores of the porous carrier, and magnetic particles with high brittleness are supported on the porous carrier that is easily deformed. Having a structure. Therefore, it is extremely easy to process the magnetic particles into a shape that reduces the pressure loss. Therefore, even when used as a cold storage material for refrigerators that perform high-speed cycle operation such as Stirling refrigerators and pulse tube refrigerators, operation with low pressure loss and high heat exchange efficiency is possible, and high refrigeration capacity is achieved. A refrigerator can be realized.

It is also possible to form the above-mentioned pulverized magnetic particles into a sheet or plate by various molding methods to produce a sheet- or plate-shaped regenerator material for cryogenic temperature. That is, the magnetic particles prepared as described above are pulverized so that the average particle diameter is several μm (the number of particles having a particle diameter of 50 μm or less is 70% or more), and a binder (binder) and a solvent are added to the obtained powder. , A dispersant, a plasticizer, and the like are added as necessary, and uniformly mixed to prepare a slurry.

Examples of the binder include, but are not limited to, polyacrylate, polymethacrylate, cellulose acetate, polyvinyl butyral, polyvinyl alcohol (PVA), polyvinyl butyral (PVB), methyl cellulose, polyethylene glycol, carboxymethyl cellulose, and the like. Can be used. As the solvent, acetone, toluene, trichlene, ethyl alcohol, ethyl acetate, water and the like can be used. As the dispersant, glycerin triolate, allylsulfonic acid, phosphates, various surfactants and the like can be used. In addition, as a plasticizer mainly added to improve the flexibility and processability of a molded article, octyl phthalate, butyl benzyl phthalate, glycerin, polyethylene glycol, saccharose acetate isobutyrate, dibutyl phthalate, diisodecyl phthalate, etc. Can be used.

Next, the obtained slurry is, for example, a metal plate;
It is coated on the surface of a plastic film and formed into a sheet, or the slurry is formed into a plate. The forming method is not particularly limited, but a doctor blade method, a roll forming method, a gravure coating method, or the like can be used. The cold storage material formed into a sheet or a plate is subjected to a heat treatment as needed, to volatilize a binder, a solvent and the like, and dried.

The sheet-like cold storage material formed as described above is
Unlike conventional cold storage materials having high brittleness, they can be deformed into various shapes. For example, by winding a sheet-shaped regenerator material into a roll shape and filling the regenerator in a refrigerator, a function as an extremely low-temperature regenerative material having low airflow resistance can be exhibited. Here, it is possible to freely change the airflow resistance by changing the winding method of the sheet-shaped regenerative material. In particular, since the form can be changed so that the ventilation resistance is reduced, it is useful as a cold storage material for a refrigerator that performs high-speed cycle operation.

Also, without coating the slurry,
After being directly dried, it can be press-formed and used as a plate-like cold storage material. That is, cooling is performed by forming a large number of ventilation holes penetrating the plate-shaped cold storage material in the thickness direction, and arranging the plate-shaped cold storage material in a multi-stage manner via fine spacers in the regenerator. A regenerator material having a uniform flow of the medium (He gas) and low airflow resistance can be obtained.

The cross-sectional shape of the ventilation hole is not particularly limited, but is preferably a circular shape which is easy to drill. In this case, the diameter of the ventilation hole is in the range of 10 μm to 1 mm, and particularly preferably in the range of 20 μm to 300 μm. Even when the cross-sectional shape of the vent hole is other than circular, it is preferable that the vent hole has a cross-sectional area corresponding to the circular shape. Further, the interval between the ventilation holes is set to 20 μm to 2 mm, more preferably 30 to 400 μm. The thickness of the plate-shaped regenerator material is preferably about 0.5 to 5 mm.

When the regenerator material in which the sheet regenerator material is wound in a roll shape is accommodated in the regenerator, the He gas as a cooling medium flows through the gap near the center of the roll in a concentrated manner. The flow as a whole medium also tends to be non-uniform. However, when the plate-shaped porous cold storage material is arranged in multiple stages as described above, the flow of the cooling medium becomes uniform, and the cold storage effect can be further enhanced.
The ventilation resistance can be arbitrarily adjusted by changing the diameter and the arrangement pitch of the ventilation holes. Further, when the plate-shaped porous regenerative material is arranged in multiple stages, the ventilation resistance can be further reduced as compared with the case where the conventional spherical magnetic particles are filled at the same filling ratio, Cycle operation at a higher speed becomes possible.

On the other hand, the heat shield material according to the present invention is formed by integrally joining the cryogenic cold storage material prepared as described above to a reinforcing member made of a material different from the cryogenic cold storage material. .

The cryogenic cold storage material is prepared, for example, by the following procedure. First, a slurry is prepared by mixing a magnetic regenerator powder obtained by crushing magnetic particles having the above composition with a binder, a solvent, and the like. Next, after the obtained slurry is filled into the pores of the porous carrier, the solvent component is evaporated to form a sheet-shaped magnetic regenerator.

Here, in order to evaporate the solvent component, it is effective to perform a heating operation or a decompression operation.
Further, as the porous carrier, a mesh metal or the like made of a fibrous metal can be used in addition to a porous metal such as a foamed metal. Further, as the constituent material of the porous carrier, Ni, Cu, Pb, Fe, Al, Ni alloy, C
Metal materials such as u alloy, Pb alloy, Fe alloy, Al alloy, and stainless steel are suitable.

The porosity of the porous metal or mesh-like metal is more preferably large so that the magnetic regenerator having a large specific heat can be filled more. Specifically, the porosity is set to 20 vol.% Or more, preferably 60 vol.% Or more, and more preferably 85 vol.% Or more.

The transition metal or alloy constituting the above-mentioned porous metal or mesh-like metal has a higher thermal conductivity at a low temperature than a general metal material. Therefore, even when the object to be cooled is cooled only by the conduction heat transfer from the refrigerator, the heat transfer efficiency by the porous metal or the mesh-like metal is high, and the magnetic cool storage material filled inside the sheet-like cool storage material is efficiently cooled. It is possible.

The binder (binder) for binding the magnetic regenerator material powder and the porous carrier is not particularly limited, but a thermoplastic resin such as polyvinyl alcohol (PVA) or carboxymethyl cellulose (CMC), an epoxy resin, A thermosetting resin such as polyimide can be suitably used.

Further, as the regenerator material for cryogenic temperature, it is possible to use a regenerator material prepared by the molten metal quenching method or a regenerator material cut or rolled as described below. That is, a molten metal melted with a predetermined composition is processed using a molten metal quenching method such as a single roll method, a twin roll method, or a centrifugal spray method, and is processed into a flake, needle, powder, or the like magnetic regenerator. A material can also be used. In this case, since the thickness of the flakes and the diameter of the needle-like or powder-like regenerator material become as thin as about 0.4 mm or less, a plurality of flakes or the like are used in an overlapping manner in the thickness direction via an adhesive (binder). You can also. Further, in the case of a magnetic regenerator material composed of a single element of a rare earth element such as Nd, it is possible to use a material obtained by cutting or rolling the ingot and processing it into a plate shape.

Among the above-mentioned magnetic regenerators, the magnetic regenerator made of an intermetallic compound is generally a brittle material, so that it is difficult to process it into a plate on an industrial scale. However, when it is formed into a plate or chip having a relatively small area, it can be manufactured by a method of cutting an ingot or a method of pulverizing the ingot and sintering the pulverized powder.

In this case, the area of each magnetic regenerator material is 1 to 1
It is preferably in the range of 000 cm ² . This area is 1
In the case of a large plate-shaped magnetic regenerator material having a size exceeding 000 cm ² , it is particularly difficult to process and has low mechanical strength. On the other hand, if a large-area object to be cooled is covered with a plate or chip-shaped magnetic regenerator material having an area of less than 1 cm ² , the number of joints between adjacent magnetic regenerator materials increases, and the heat shield effect is reduced. Therefore, although the area of each magnetic cold accumulating material is in the range of 1~1000cm ^2, 2~500cm ²
Is more preferable, and the range of 3 to 100 cm ² is more preferable. The thickness of each magnetic regenerator material is preferably in the range of 0.5 to 50 mm.

The reinforcing member for integrally joining the magnetic regenerator material supports and reinforces a magnetic regenerator material that cannot be processed into a large shape or a magnetic regenerator material that does not have sufficient structural strength, in addition to the heat shield effect by itself. Has functions. Ni, Cu, Fe, Al, N
In addition to metal materials such as i-alloy, Cu alloy, Fe alloy, Al alloy, and stainless steel, epoxy resin and fiber reinforced plastic (FRP) can be used. Among the above constituent materials, Cu, Al, Cu alloy, and Al alloy are preferable from the viewpoint of high thermal conductivity especially in a low temperature range. Further, an Fe-based metal material such as stainless steel is preferable from the viewpoint of inexpensiveness.

Various magnetic cold storage materials are integrally joined to the reinforcing member to form the cryogenic heat shield material according to the present invention. Here, as an adhesive for joining the sheet-shaped magnetic regenerator material in which the magnetic particles are filled into the pores of the porous carrier to the reinforcing member, a bonding agent used for joining the magnetic particles to the porous carrier is used. It is also possible to use an agent (binder).

That is, the slurry prepared by mixing the magnetic particles with a binder and a solvent is filled in the pores of the porous carrier, and the sheet-shaped magnetic regenerator material in a state before the solvent component is evaporated. Is dried in a state where the magnetic particles are brought into contact with the reinforcing member and fixed, so that the sheet-shaped magnetic cold storage material and the reinforcing member are simultaneously integrated with the binder (binder) joining the magnetic particles and the porous carrier. Can be joined.

Further, in order to increase the adhesion between the magnetic regenerator and the reinforcing member and reduce the thermal resistance and at the same time to increase the joint strength between the two members, the magnetic regenerator is screwed to the reinforcing member, or a belt or wire is used. It is also effective to bind the magnetic cool storage material from outside.

According to the heat shield material having the above-described structure, a heat shield material that can be easily processed into an arbitrary shape and that can maintain a cooled object at a low temperature for a long time can be obtained. In particular, the temperature stability of equipment operating in a cryogenic temperature range, such as a superconducting wire, a superconducting element, and an infrared sensor, can be greatly improved.

[0072]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described more specifically with reference to the following examples.

Example 1 First, an ErNi mother alloy was prepared by high frequency melting. Next, this ErNi master alloy was mechanically pulverized to obtain an alloy powder having a size of 200 mesh or less. Next, an aqueous solution in which polyvinyl alcohol as a binder was dissolved at a concentration of 4% by weight was added to the obtained ErNi alloy powder at a ratio of 25% by weight of the alloy powder, and the mixture was uniformly kneaded to prepare a slurry paste. .

On the other hand, many porous Ni carriers (trade name: Celmet, manufactured by Sumitomo Electric Industries, Ltd.) having a thickness of 1.6 mm, a width of 50 mm, a length of 400 mm, and a porosity of 95 vol. Prepared.

Next, the slurry paste prepared as described above was uniformly filled in the pores of each of the Ni porous carriers described above, and then heated to a temperature of 1 in a reduced pressure atmosphere (1 to 100 Torr).
The moisture was evaporated by drying at 20 ° C. for 1 hour to prepare a sheet-like regenerative material in which ErNi magnetic particles adhered to a porous carrier via a binder.

Next, with respect to each of the obtained sheet-like regenerative materials,
Rolling was performed using an embossing roll having irregularities on the surface to prepare a sheet-like cold storage material for extremely low temperature according to Example 1 having a thickness of 0.8 mm.

The sheet-like cold storage material 1 for cryogenic use according to the first embodiment has a large number of magnetic particles (ErNi alloy) in the pores 3 of the Ni porous carrier 2 as schematically shown in FIG. Powder)
4 has a packed tissue structure. In addition, each magnetic particle 4
Is firmly bound to the porous carrier 2 via polyvinyl alcohol as a binder. A bump (not shown) having a height of 0.05 mm is formed on the surface of the sheet-like cold storage material 1 for cryogenic temperature by rolling using an embossing roll.

Next, a plurality of sheet-like regenerator materials were joined by spot welding the end portions of the obtained sheet-like regenerative materials for cryogenic temperature 1 to form a long ribbon-like regenerator material having a width of 50 mm. did.
Next, the obtained ribbon-shaped cold storage material was wound to obtain a roll-shaped cold storage material for cryogenic use. In this roll-shaped cold storage material, adjacent sheet-shaped cold storage materials are isolated by bumps (projections) formed on the surface.

Then, as shown in FIG. 1, the roll-shaped regenerator material for cryogenic temperature 1 was filled in a regenerator 5 having an inner diameter of 25 mm and a height of 50 mm. The filling ratio of the magnetic particles 4 in the regenerator 5 was 73 vol.%. When this regenerator 5 was used as a third-stage regenerator of a three-stage pulse tube refrigerator and operated at an operation frequency of 10 Hz,
As a refrigerating capacity at 10 ° K, 0.14 W was obtained.

Comparative Example 1 On the other hand, the ErNi alloy prepared in Example 1 was melted, and the obtained molten alloy was dispersed by a centrifugal spray method and simultaneously solidified by rapid cooling to prepare spherical magnetic particles. The obtained magnetic particles are sieved to have a diameter of 0.15 to 0.18 mm.
Spherical magnetic particles in the range of were selected. Next, the selected magnetic granules were stored in the regenerator (inner diameter 25) used in Example 1 shown in FIG.
mm × 50 mm in height). The filling ratio of the magnetic particles 4 in the regenerator 5 was 62 vol.%.

When the regenerator 5 filled with the spherical magnetic particles was used as the third regenerator of the pulse tube refrigerator in the same manner as in the first embodiment and operated under the same conditions, the lowest temperature reached The temperature was 16 ° K without reaching 10 ° K, and sufficient refrigeration capacity could not be obtained.

Embodiment 2 FIG. 3 is a perspective view showing the shape and structure of a cryogenic cold storage material 1a according to Embodiment 2. This cryogenic cold storage material 1a is:
The sheet-like cold storage material prepared in Example 1 was manufactured by bending a press at intervals in the longitudinal direction to form a plurality of protrusions 6. When the folded sheet-shaped regenerator is wound as shown in FIG.
Since the sheet-shaped cold storage material adjacent in the radial direction is isolated by the convex portion 6, the ventilation resistance in the width direction of the sheet-shaped cold storage material becomes small.

The regenerator material 1a for cryogenic temperature according to the second embodiment was filled in a regenerator 5 as shown in FIG. 1 and used as a third stage regenerator of a pulse tube refrigerator in the same manner as in the first embodiment. When operated under the conditions, 0.11 W was obtained as a refrigeration capacity at 10 ° K.

Example 3 In Example 1, a Ni porous carrier having a thickness of 2.0 mm, a diameter of 25 mm and a porosity of 97% was filled with ErNi magnetic particles to prepare a sheet-like regenerator material. Many holes having a diameter of 0.2 mm were formed at intervals of 0.5 mm in the sheet-like cold storage material by machining. This regenerative material was filled in the same regenerator as in Example 1 and operated under the same conditions as the third stage regenerator of the pulse tube refrigerator. As a result, a refrigerating capacity at 10 K ° of 0.13 W was obtained.

The cryogenic cold storage materials 1 and 1 according to the above embodiments.
In (a), a working medium (refrigerant) such as He gas passes through a flow path having low resistance between adjacent sheet-like cold storage materials, and performs heat exchange on the surface of the sheet-like cold storage materials. Therefore, it has been found that even when a high-speed cycle operation is performed, the pressure loss is small and the heat exchange rate is high, so that excellent refrigeration efficiency can be exhibited.

In particular, even if a strong working of winding and forming into a coil shape is performed, the porous carrier is freely deformed.
The magnetic particles are less likely to be cracked or damaged, and can be processed into a shape with reduced pressure loss.

In Example 1 and Comparative Example, in Example 1, the filling ratio of the magnetic particles in the regenerator could be increased without increasing the pressure loss.
It is considered that a large difference occurred in the refrigerating capacity.

In the above embodiment, the pores of the porous carrier are filled with magnetic particles to form a composite, thereby forming a sheet-like cold storage material for cryogenic use. The carrier and the magnetic particles can be combined to form a sheet-like cold storage material for cryogenic use.

That is, it is also possible to form a magnetic regenerator material in the form of a sheet by sandwiching magnetic particles between soft metal sheets such as Pb and integrating them by pressing.

In addition, a so-called canning, in which the inside of a bag-shaped member formed of a metal material such as Ni, Cu, Pb, and Al is filled with magnetic particles and then vacuum-sealed and sealed, is performed.
The canned sheet-shaped bag may be further rolled to integrate the metal material and the magnetic particles into a sheet-shaped magnetic cold storage material.

Further, the magnetic regenerator material is finely pulverized so as to have a particle diameter of about several μm, and a binder and a solvent are added to the obtained magnetic powder to form a slurry. It may be formed by a method or the like into a sheet-shaped formed body, and the sheet-shaped formed body may be heated to evaporate the binder component to form a sheet-shaped magnetic regenerator. In addition, it is also possible to perforate the said sheet-shaped molded object, and to form a sheet-shaped cold storage material with little airflow resistance.

Further, after a metal having a low melting point such as Pb and not reacting with the magnetic particles is coated on the surface of the magnetic particles by a mechanical alloying method or the like, the coated magnetic particles are formed into a sheet. Then, the obtained compact is heat-treated to dissolve the low-melting-point metal, and the low-melting-point metal firmly binds the magnetic particles to each other, whereby a sheet-like magnetic regenerator material can be produced. .

Next, a plate-like cold storage material for cryogenic temperature formed by molding pulverized magnetic particles will be described with reference to the following examples.

Example 4 A mother alloy of a magnetic material having a composition of HoCu ₂ was prepared by high frequency melting. This mother alloy is pulverized using a jaw crusher, a hammer mill, and a ball mill in this order,
A magnetic alloy powder having an average particle size of 10 μm was prepared. 7% by weight of an acrylic resin as a binder, 70% by weight of metal isobutyl ketone (MIBK) as a solvent, and 2.8% by weight of dibutyl phthalate as a plasticizer were added to the magnetic alloy powder. The mixture was added and mixed with alumina balls using a pot roller for 24 hours to prepare a uniform slurry.

Next, after drying the obtained slurry,
The particles were passed through a # 60 sieve to make the particle diameter uniform. This dry powder was filled in a mold and pressed under a forming pressure of 180 kg / cm ² to form a plate-shaped cold storage material having a diameter of 28 mm and a thickness of 1 mm. Further, as shown in FIG. 4, a ventilation hole (through hole) 6 having a diameter of 100 μm is formed in the plate-shaped cold storage material.
Was mechanically perforated at a 200 μm pitch. Further, the obtained porous cold storage material plate was heated at a temperature of 70 in a nitrogen gas atmosphere.
It was degreased at 0 ° C. for 2 hours to obtain a plate-shaped porous cold storage material 1b.

With the obtained fifty plate-shaped porous regenerative materials 1b inserted between each plate as a spacer using a Teflon mesh material as a spacer, a two-stage expansion type pulse tube refrigerator as shown in FIG. The refrigerator was assembled by stacking and arranging in multiple stages in the axial direction of the second stage regenerator 5a. Then, as a result of operating this refrigerator at a frequency of 20 Hz, the lowest temperature reached 4.0 K, and excellent refrigeration performance was obtained.

Comparative Example 2 The mother alloy (HoCu ₂ ) prepared in Example 4 was melted, and the obtained molten alloy was rapidly solidified by centrifugal spraying (RDP) to prepare spherical magnetic particles. The obtained magnetic particles were sieved to select spherical magnetic particles having a diameter of 0.15 to 0.18 mm. The magnetic particles were filled in the second-stage regenerator 5a of the pulse tube refrigerator used in Example 4, and a refrigeration test was performed under the same conditions as in Example 4. As a result, the lowest temperature was 13.2K. .

Example 5 A mother alloy of a magnetic material having a composition of Er ₃ Ni was prepared by high frequency melting. This mother alloy is pulverized using a jaw crusher, a hammer mill, and a ball mill in this order,
A magnetic alloy powder having an average particle size of 8 μm was prepared. This magnetic alloy powder was added with 6 parts as a binder based on the weight of the alloy powder.
Wt% acrylic resin, 70 wt% metal isobutyl ketone (MIBK) as solvent, and 2. plasticizer.
5% by weight of dibutyl phthalate was added, and mixed with alumina balls by a pot roller for 24 hours to prepare a uniform slurry.

Next, the obtained slurry was molded by a doctor blade method to prepare a long sheet-like regenerator material having a width of 60 mm and a thickness of 300 μm.

Next, a 200 μm diameter was added to the sheet-shaped cold storage material.
m were mechanically pierced at a pitch of 300 μm. The obtained porous sheet-shaped regenerator material was wound into a roll-shaped regenerator material having a diameter of 28 mm and a height of 60 mm, and degreased at 700 ° C. for 2 hours in a nitrogen atmosphere in a state of extremely low temperature according to Example 5. A cold storage material was prepared.

The cryogenic regenerator material according to Example 5 thus formed into a roll was filled in the second regenerator of the two-stage expansion type pulse tube refrigerator to assemble the refrigerator. Then, as a result of operating this refrigerator at a frequency of 20 Hz, the minimum temperature reached 4.5 K, and excellent refrigeration performance was obtained.

Comparative Example 3 The master alloy (Er ₃ Ni) prepared in Example 5 was melted, and the obtained molten alloy was rapidly solidified by centrifugal spraying (RDP) to prepare spherical magnetic particles. The obtained magnetic particles were sieved to select spherical magnetic particles having a diameter of 0.15 to 0.18 mm. The magnetic particles were filled in the second stage regenerator of the pulse tube refrigerator used in Example 5, and a refrigeration test was performed under the same conditions as in Example 5. As a result, the lowest temperature was 17.0K.

Example 6 A melt of Nd was dispersed and quenched by Ar gas atomization into magnetic powder. The obtained powder was sieved to select a powder having a particle size of 100 μm or less. Next, an aqueous solution in which polyvinyl alcohol as a binder was dissolved at a concentration of 2% by weight was added to the obtained Nd powder at a ratio of 20% with respect to the powder weight, and the mixture was uniformly kneaded to prepare a slurry paste. .

On the other hand, many porous Ni carriers (trade name: Celmet, manufactured by Sumitomo Electric Industries, Ltd.) having a thickness of 1.6 mm, a width of 50 mm, a length of 400 mm, and a porosity of 95 vol. Prepared.

Next, the slurry paste prepared as described above was uniformly filled in the pores of each of the Ni porous carriers described above, and then heated at a temperature of 1 to 100 Torr in a reduced pressure atmosphere (1 to 100 Torr).
By drying at 20 ° C. for 1 hour to evaporate the water, a sheet-like cold storage material having Nd magnetic particles adhered to a porous carrier via a binder was prepared.

Next, for each of the obtained sheets of cold storage material,
The sheet was rolled by rolling using an embossing roll having irregularities on the surface to prepare a sheet-like cold storage material for extremely low temperature according to Example 6 having a thickness of 0.8 mm.

A bump having a height of 0.05 mm is formed on the surface of the sheet-like cold storage material for extremely low temperature according to the sixth embodiment by rolling using an embossing roll.

Next, a plurality of sheet-like regenerator materials were joined by spot welding the end portions of the obtained sheet-like regenerative materials for cryogenic temperature to form a long ribbon-like regenerator material having a width of 50 mm. . Next, the obtained ribbon-shaped cold storage material was wound to obtain a roll-shaped cold storage material for cryogenic use. In this roll-shaped cold storage material,
Adjacent sheet-like cold storage materials are isolated by bumps (projections) formed on the surface.

Then, the roll-shaped regenerator material for cryogenic temperature was filled in a regenerator having an inner diameter of 25 mm and a height of 50 mm. This regenerator is the second stage of the two-stage pulse tube refrigerator.
When used as a stage regenerator and operated at an operation frequency of 20 Hz, the lowest temperature reached 6.3 K, and excellent refrigerator performance was obtained.

Comparative Example 4 On the other hand, using Nd prepared in Example 6, a diameter of 50% was used.
A round bar of mm × 300 mm was prepared, and the Nd melt was dispersed and rapidly solidified at the same time by a rotating electrode method (REP) using the obtained Nd round bar as an electrode to prepare spherical magnetic particles. The obtained magnetic particles are sieved and the diameter is 0.15 to 0.15.
Spherical magnetic particles in the range of 0.18 mm were selected. Next, the selected magnetic particles were stored in the regenerator (inner diameter 25) used in Example 6.
mm x 50 mm height).

Then, the regenerator filled with the spherical magnetic particles was used as the second regenerator of the pulse tube refrigerator in the same manner as in Example 6 and operated under the same conditions. It was 18.2K without reaching 0.3K, and a sufficient refrigeration capacity could not be obtained.

Next, the cryogenic heat shield material according to the present invention will be described based on the following examples.

Example 7 First, a HoCu ₂ mother alloy was prepared by high frequency melting.
Next, this HoCu ₂ mother alloy was mechanically pulverized to 200 mm.
An alloy powder having a mesh or less was used. Next, the obtained HoCu
₍₂₎ An aqueous solution in which polyvinyl alcohol as a binder was dissolved at a concentration of 4% by weight in
% And kneaded uniformly to prepare a slurry-like paste.

On the other hand, there are many Ni porous carriers (trade name: Celmet, manufactured by Sumitomo Electric Industries, Ltd.) having a thickness of 1.6 mm, a width of 50 mm, a length of 400 mm, and a porosity of 95 vol. Prepared.

Next, the slurry paste prepared as described above was uniformly filled into the pores of each of the Ni porous carriers to prepare a sheet-like cold storage material 36a.

On the other hand, as shown in FIG.
A cylindrical reinforcing member (for the first layer) 37a having a diameter of 200 mm and a height of 300 mm and a reinforcing member (for the second layer) 37b having a diameter of 230 mm and a height of 350 mm was prepared. Then, before the binder of the sheet-like cold storage material 36a dries, the sheet-like cold storage material 36a is separated from the reinforcing members 37a,
It adhered to the outer surface of 37b. That is, the paste is excessively applied between each sheet-like cold storage material 36a and the reinforcing members 37a, 37b made of Cu to such an extent that the paste exudes from the porous carrier made of Ni, and is a binder component in the paste. The sheet-like cold storage material 36 is formed by the adhesive force of polyvinyl alcohol.
a and the reinforcing members 37a and 37b made of Cu were integrally joined. Further, the sheet-like cold storage material 36a and the reinforcing members 37a, 37
The sheet-like cold storage material 36a was screwed with a fixing screw 38 in order to improve the heat transfer between the sheet-like cold storage material 36a. Thereafter, by drying at 120 ° C. for 1 hour under a reduced pressure atmosphere, as shown in FIG.
Heat shield materials 39a and 39b in which 6a and reinforcing members 37a and 37b were integrally joined were prepared.

On the other hand, instead of HoCu ₂ , Er ₃ Ni
Was filled in the holes of the Ni porous carrier to prepare a sheet-like cold storage material 36b as shown in FIG. Further, as shown in FIG. 5, a bottomed cylindrical reinforcing member (for the third layer) 37c of 260 mm in diameter × 400 mm in height, made of Cu material having a thickness of 1 mm, 290 mm in diameter × 450 mm in height
And a bottomed cylindrical reinforcing member (for the fifth layer) 37e having a diameter of 310 mm and a height of 500 mm were prepared.

The reinforcing members 37c, 37d, 37e
A sheet-like cold storage material 36b containing Er ₃ Ni magnetic particles is integrally joined to the outer surface of the heat shield material 39c, 39d, 3 as shown in FIG.
9e was prepared.

Then, the heat shield materials 39a to 39e for the first to fifth layers prepared as described above are concentrically arranged in the vacuum vessel 33 as heat shield materials for the low-temperature cooler 30 shown in FIG. Thus, a low-temperature cooler for cooling the superconducting magnet 31 was assembled. As a heat shield material for the sixth to tenth layers, a conventional heat shield material 32 made of only a Cu material having a thickness of 1 mm as shown in FIG. 11 was arranged concentrically.

The low-temperature cooler 30 assembled as described above
, A total of 10 layers of heat shield material 3 are provided by a two-stage cooling type GM (Gifford McMaffon) refrigerator 10.
After cooling 9a to 39e and 32 to 32, the heat switch 35 is turned off to disconnect the thermal contact between the GM refrigerator 10 and the heat shield material.
The surface temperature was measured. As a result, the temperature reached to 4.0 K by the cooling action of the GM refrigerator 10 is still 5.0 K even after 100 hours have passed since the GM refrigerator 10 was separated, and excellent heat shield characteristics could be confirmed. Was.

Example 8 A HiCu ₂ alloy ingot was prepared by high frequency melting.
After mechanically cutting this ingot, it was subjected to grinding to prepare a large number of chip-shaped magnetic regenerators 20 mm long × 20 mm wide × 3 mm thick.

On the other hand, a cylindrical reinforcing member having a bottom and the same dimensions as the reinforcing members 37a and 37b for the first layer and the second layer used in Example 7 was prepared. And, of the chip-shaped magnetic regenerator material, the chip-shaped magnetic regenerative material to be joined to the side surface of the reinforcing member was subjected to finish processing into a curved surface shape so as to match the curvature of the side surface of the reinforcing member. On the other hand, the chip-shaped magnetic regenerator for joining to the bottom surface of the reinforcing member was kept flat.

Then, a tip-shaped magnetic regenerative material finished in a curved shape is coated on the side surface of the reinforcing member (made of Cu) with ethyl 2-.
While bonding via a cyanoacrylate instant adhesive (Aron Alpha: manufactured by Toa Gosei Chemical Industry Co., Ltd.), a planar chip-shaped magnetic regenerator material was similarly bonded to the bottom surface of each reinforcing member. In addition, since it is impossible to cover the circular bottom surface of each reinforcing member with a square chip-shaped magnetic regenerator material, the chips protruding from the outer periphery of the bottom surface are finished in a shape matching the outer peripheral shape. . As a result, a heat shield material (for the first layer and for the second layer) in which the chip-shaped magnetic regenerative material and the reinforcing member were integrally joined was prepared.

On the other hand, on the side and bottom surfaces of the Cu reinforcing members (for the third to fifth layers) prepared in Example 7, chip-shaped magnetic regenerators made of Er ₃ Ni processed in the same manner as above. By bonding the materials, heat shield materials for the third to fifth layers were respectively prepared.

Then, the heat shield materials for the first to fifth layers prepared as described above were combined with the low-temperature cooler 3 shown in FIG.
A low-temperature cold storage device for cooling the superconducting magnet 31 by concentrically disposing it in the vacuum vessel 33 as a heat shield material of No. 0 was assembled. As a heat shield material for the sixth to tenth layers, a conventional heat shield material 32 made of only a Cu material having a thickness of 1 mm as shown in FIG. 11 was arranged concentrically.

The low-temperature cooler 30 assembled as described above
After cooling a total of 10 layers of heat shield material by a two-stage cooling type GM (Gifford McMahon) refrigerator 10, the thermal switch 35 is turned off to disconnect thermal contact between the GM refrigerator 10 and the heat shield material. In this state, the surface temperature of the innermost heat shield material was measured. as a result,
The temperature reached to 4.0K by the cooling action of the GM refrigerator 10 was 6.7K even after 100 hours had passed after the GM refrigerator 10 was separated, and excellent heat shield characteristics were confirmed.

Example 9 A Nd metal lump was hot-rolled in an inert gas atmosphere to obtain a plate-shaped magnetic regenerator material having a thickness of 3 mm. On the other hand, the plate-shaped magnetic regenerative cold storage using an epoxy adhesive (Sumikadyne: manufactured by Sumitomo Chemical Co., Ltd.) was applied to the outer surfaces of the first to fifth layer Cu reinforcing members prepared in Example 7. The materials were glued. Further, in order to improve the heat transfer between the Nd magnetic regenerator material and the Cu reinforcing member, both members were screwed together with fixing screws 38 in the same manner as shown in FIG.

Then, the heat shield materials for the first to fifth layers prepared as described above were combined with the low-temperature cooling device 3 shown in FIG.
A low-temperature cold storage device for cooling the superconducting magnet 31 by concentrically disposing it in the vacuum vessel 33 as a heat shield material of No. 0 was assembled. As a heat shield material for the sixth to tenth layers, a conventional heat shield material 32 made of only a Cu material having a thickness of 1 mm as shown in FIG. 11 was arranged concentrically.

The low-temperature cooling device 30 assembled as described above
After cooling a total of 10 layers of heat shield material by a two-stage cooling type GM (Gifford McMahon) refrigerator 10, the thermal switch 35 is turned off to disconnect thermal contact between the GM refrigerator 10 and the heat shield material. In this state, the surface temperature of the innermost heat shield material was measured. as a result,
The temperature reached to 4.0K by the cooling action of the GM refrigerator 10 was 8.2K even after 100 hours had passed after the GM refrigerator 10 was separated, and excellent heat shield characteristics could be confirmed.

Comparative Example 5 All the heat shield materials of the first to tenth layers were
A low-temperature cooler of Comparative Example 5 was assembled in the same manner as in Example 7 except that it was formed of a conventional heat shield material consisting only of a Cu material having a thickness of 1 mm as shown in FIG.

The low-temperature cooling device 30 assembled as described above
After cooling a total of 10 layers of the heat shield material by a two-stage cooling type GM (Gifford McMahon) refrigerator 10, the thermal switch 35 is turned off to disconnect the thermal contact between the GM refrigerator 10 and the heat shield material. In this state, the surface temperature of the innermost heat shield material was measured. as a result,
The temperature reached to 4.0K by the cooling action of the GM refrigerator 10 rapidly increased to 22K after 100 hours after the GM refrigerator 10 was separated, and it can be reconfirmed that the heat shield effect is small. Was.

In the above embodiment, the heat shield material in which a sheet-like or chip-like magnetic cold storage material is integrally joined to the outer surface of the Cu reinforcing member is shown. Alternatively, it is possible to exhibit the same heat shield characteristics even when joined to either of the inner sides.

As shown in FIG. 6, by joining the magnetic regenerators 40 on both sides of the reinforcing member 37, a heat shield 41 having a greater regenerative effect and having excellent heat shielding properties can be obtained. Further, as shown in FIG. 7, the reinforcing member 42 may have a double structure, and a heat shield material 44 in which a gap is filled with a cold storage material powder 43 may be used. As shown in FIG. 8, a heat shield material 46 in which the cold storage material powder 43 is filled may be formed inside a pipe-like reinforcing member 45. In this case, a binder may be mixed with the cold storage material powder 43 as necessary.

According to the heat shield material according to the above embodiment,
Equipment that can be easily processed into an arbitrary shape and that can maintain the object to be cooled at a low temperature for a long period of time, and that operates in a cryogenic region, such as superconducting wires, superconducting elements, and infrared sensors. Temperature stability can be greatly improved.

[0135]

As described above, according to the cold storage material for cryogenic use according to the present invention, the pores of the porous carrier having low air flow resistance and good workability are filled with magnetic particles. The magnetic particles having high brittleness have a structure supported on a porous carrier which is easily deformed. Therefore, it is extremely easy to process the magnetic particles into a shape having a small pressure loss without causing cracking or damage. Therefore, even when used as a cold storage material for refrigerators that perform high-speed cycle operation such as Stirling refrigerators and pulse tube refrigerators, operation with low pressure loss and high heat exchange efficiency is possible, and high refrigeration capacity is achieved. A refrigerator can be realized.

Further, according to the heat shield material according to the present invention, it is easy to work into an arbitrary shape, and it is possible to maintain the object to be cooled at a low temperature for a long time.

[Brief description of the drawings]

FIG. 1 is a cutaway perspective view showing a regenerator filled with a cryogenic cold storage material according to the present invention.

FIG. 2 is a diagram showing a particle structure of a cryogenic cold storage material according to the present invention, and is an enlarged view of a part II in FIG. 1;

FIG. 3 is a perspective view showing another embodiment of the cryogenic cold storage material according to the present invention.

FIG. 4 is a cutaway perspective view showing a regenerator filled with a cryogenic regenerator according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing one embodiment of the heat shield material according to the present invention.

FIG. 6 is a perspective sectional view showing another embodiment of the heat shield material according to the present invention.

FIG. 7 is a perspective sectional view showing another embodiment of the heat shield material according to the present invention.

FIG. 8 is a perspective view showing another embodiment of the heat shield material according to the present invention.

FIG. 9 is a cross-sectional view illustrating a configuration of a main part of the GM refrigerator.

FIG. 10 is a sectional view showing a configuration example of a low-temperature cooler using a GM refrigerator and a heat shield material.

FIG. 11 is an enlarged sectional view of a portion XI in FIG. 10;

[Explanation of symbols]

Reference Signs List 1, 1a, 1b Cold storage material for cryogenic temperature 2 Porous carrier 3 Void portion 4 Magnetic particles (HoCu ₂ alloy powder) 5, 5a Cold storage device (second cold storage device) 6 Vent hole 10 GM refrigerator 11 First Cylinder 12 Second cylinder 13 Vacuum container 14 First regenerator 15 Second regenerator 16, 17 Seal ring 18 First regenerator material 19 Second regenerator material (cryogenic material for cryogenic temperature) 20 First expansion chamber 21 Second expansion chamber 22 1st cooling stage 23 2nd cooling stage 24 Compressor 30 Low temperature cooler 31 Superconducting magnet 32 Heat shield material 33 Vacuum container 34 Support material 35 Heat switch 36a, 36b Sheet-like cold storage material 37, 37a, 37b, 37c, 37d, 37e Reinforcing member 38 Fixing screw 39a, 39b, 39c, 39d, 39e Heat shield material 40 Magnetic cold storage material 41, 44, 46 Heat shield material 4 , 45 reinforcing member 43 cold accumulating material powder

Continuing from the front page (72) Inventor Rohana Chandratilaka 1st Toshiba Research & Development Center, Komukai-ku, Kawasaki-shi, Kanagawa Prefecture (72) Inventor Hideki Nakagome Hideki Nakagome Toshiba-cho, Koyuki-ku, Kawasaki-shi, Kanagawa No. 1 Inside Toshiba R & D Center

Claims (14)

[Claims] 1. A cold storage material for cryogenic use, wherein magnetic particles containing a rare earth element are filled in pores of a porous carrier. 2. The cold storage material for cryogenic use according to claim 1, wherein the porous carrier is a sheet-like porous metal or a mesh-like metal. 3. The cold storage material for cryogenic use according to claim 1, wherein the porosity of the porous carrier is 90% or more. 4. The cold storage material for cryogenic use according to claim 1, wherein the porous carrier is a foamed metal. 5. The cold storage material for cryogenic use according to claim 1, wherein the porous carrier is formed in a sheet shape and a plurality of projections are formed on at least one surface of the porous carrier. 6. A magnetic particle comprising a rare earth element-containing magnetic particle mixed with a binder, a solvent, a dispersant and a plasticizer to prepare a uniform slurry, and forming the obtained slurry into a sheet. A cold storage material for cryogenic use, characterized in that they are joined to each other. 7. The cold storage material for cryogenic use according to claim 6, wherein a large number of ventilation holes are formed in the sheet-like molded body made of magnetic particles. 8. A refrigerator comprising a regenerator filled with the cryogenic material according to any one of claims 1 to 7. 9. The refrigerator according to claim 8, wherein the cryogenic regenerator material is filled in the regenerator in a state of being wound in a roll shape. 10. The cold storage material for cryogenic use is composed of a plate-shaped cold storage material element having a large number of air holes, and a plurality of cold storage material elements are filled in a state of being stacked in multiple stages in the axial direction of the cool storage device. The refrigerator according to claim 8, wherein: 11. The cryogenic cold storage material according to claim 1, which is integrally joined to a reinforcing member made of a material different from the cryogenic cold storage material. Cool storage material. 12. The cryogenic material according to claim 11, wherein the reinforcing member is made of at least one metal material selected from Cu, Al, Fe, and Ni, or an alloy containing the metal material as a main component. Heat shield material. 13. The cold storage material for cryogenic use is a sheet-like cold storage material formed by filling magnetic particles together with a binder into pores of a porous carrier. Cryogenic heat shield material. 14. The cryogenic heat shield material according to claim 13, wherein the cryogenic cold storage material and the reinforcing member are joined by the binder.