Method for producing granulated particles for cold storage material particles, method for producing cold storage material particles, method for producing cold storage unit, method for producing refrigeration unit, method for producing cryopump, method for producing superconducting magnet, method for producing nuclear magnetic resonance imaging device, method for producing nuclear magnetic resonance device, method for producing magnetic field-applied single-crystal pulling device, and method for producing helium recondensation device

Abstract

To provide a method for producing granulated particles for cold storage material particles, enabling a reduction in the production cost of the cold storage material particles.SOLUTION: A method for producing granulated particles for cold storage material particles according to an embodiment includes: mixing a raw material powder comprising a rare-earth oxysulfide containing at least one rare-earth element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu or a raw material powder comprising a rare-earth oxide containing at least one rare-earth element with a binder containing 0.01 wt.% or more to 40 wt.% or less of an organic substance to prepare a raw material mixture; and then granulating the raw material mixture by tumbling granulation, stirring granulation, extrusion, spraying, or press molding, wherein the granulated particles for cold storage material particles have a carbon level of 0.001 wt.% or more and 50 wt.% or less and a relative density of 10% or more and 50% or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a method for manufacturing granulated particles for regenerator particles, a method for manufacturing regenerator particles, a method for manufacturing a regenerator, a method for manufacturing a refrigerator, a method for manufacturing a cryopump, a method for manufacturing a superconducting magnet, a method for manufacturing a nuclear magnetic resonance imaging device, a method for manufacturing a nuclear magnetic resonance device, a method for manufacturing a magnetic field application type single crystal pulling device, and a method for manufacturing a helium recondensation device. [Background technology]

[0002] In recent years, superconducting technology has made remarkable progress, and as the fields of application of superconducting technology expand, the development of small, high-performance cryogenic refrigerators has become essential. Cryogenic refrigerators are required to be lightweight, small, and highly thermally efficient. Cryogenic refrigerators are being put to practical use in a variety of application fields.

[0003] A cryogenic refrigerator is equipped with a regenerator filled with multiple regenerator materials. For example, cold is generated by heat exchange between the regenerator material and helium gas passing through the regenerator. For example, in superconducting MRI devices and cryopumps used in semiconductor manufacturing equipment, refrigerators using refrigeration cycles such as the Gifford-McMahon (GM) type, Stirling type, or pulse tube type are used.

[0004] High-performance refrigerators are also essential for magnetic levitation trains, which use superconducting magnets to generate magnetic force. Recently, high-performance refrigerators have also been used in superconducting energy storage devices (SMES) and magnetic field application type single crystal pulling devices for manufacturing high-quality silicon wafers. In addition, the development and practical application of pulse tube refrigerators, which are expected to be highly reliable, is also being actively pursued.

[0005] In the above-mentioned superconducting magnets and MRI devices, the liquid helium used evaporates, making the supply of liquid helium a problem. In recent years, the helium depletion problem has become more serious, leading to difficulties in obtaining it and affecting the industrial sector.

[0006] In order to reduce the consumption of liquid helium and ease the burden of maintenance such as replenishment, helium recondensing devices that recondense evaporated helium have been put into practical use and are in high demand. These helium recondensing devices also use GM refrigerators or pulse tube refrigerators that cool the helium to a temperature of 4K to liquefy it.

[0007] In a refrigerator, a working medium such as compressed helium (He) gas flows in one direction through a regenerator filled with a regenerator material, supplying its thermal energy to the regenerator material. The expanded working medium then flows in the opposite direction through the regenerator, receiving thermal energy from the regenerator material. As the heat recovery effect in this process improves, the thermal efficiency of the working medium cycle improves, making it possible to achieve lower temperatures. In order to ensure smooth exchange of thermal energy between the helium gas and the regenerator material, it is desirable for the regenerator material to have a high thermal conductivity.

[0008] Here, the higher the specific heat per unit volume of the cold storage material mounted in the cold storage unit, the more heat energy the cold storage material can store, and therefore the more the refrigeration capacity of the refrigerator is improved. For this reason, it is desirable to fill the cold storage unit with a cold storage material that has a high specific heat at low temperatures on the low temperature side and a cold storage material that has a high specific heat at high temperatures on the high temperature side.

[0009] The magnetic regenerator material exhibits a high volumetric heat capacity in a specific temperature range depending on its composition. Therefore, by combining magnetic regenerator materials with different compositions that exhibit different volumetric heat capacities, the regenerator capacity can be increased, and the refrigeration capacity of the refrigerator can be improved.

[0010] Furthermore, the higher the thermal conductivity and thermal transfer coefficient of the cold storage material filled in the cold storage unit, the more efficient the transfer of thermal energy becomes, and the more efficient the refrigerator becomes.

[0011] In conventional refrigerators, freezing at 4K has been achieved by filling the high-temperature side of the regenerator with metallic regenerator particles such as lead (Pb), bismuth (Bi), or tin (Sn), and filling the low-temperature side of the regenerator (below 20K) with metallic magnetic regenerator particles such as Er3Ni, ErNi, or HoCu2.

[0012] In recent years, attempts have been made to improve the cooling capacity of refrigerators by replacing some of the metal-based magnetic regenerator particles with ceramic magnetic regenerator particles such as Gd2O2S, Tb2O2S, Dy2O2S, Ho2O2S, and GdAlO3, which have high specific heat in the temperature range from 2K to 10K.

[0013] The above-mentioned ceramic magnetic regenerator particles are obtained through a multi-stage manufacturing process, such as mixing raw materials and binders, granulation, degreasing at several hundred degrees, sulfurization at several hundred degrees, and sintering at several thousand degrees. Therefore, if degreasing and sulfurization can be carried out at lower temperatures than in the past, the manufacturing cost and environmental load can be reduced. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] JP 2003-73661 A [Patent Document 2] JP 2003-213252 A [Patent Document 3] International Publication No. 2018 / 025581 Summary of the Invention [Problem to be solved by the invention]

[0015] An object of the present invention is to provide a method for producing granulated particles for use in cooling accumulator particles, which can reduce the production cost of cooling accumulator particles. [Means for solving the problem]

[0016] In one embodiment, a method for producing granulated particles for use as cold storage material particles includes mixing a raw material powder containing a rare earth oxysulfide containing at least one rare earth element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, or a raw material powder containing a rare earth oxide containing the at least one rare earth element, with a binder containing 0.01% by weight to 40% by weight of an organic substance to obtain a raw material mixture, and granulating the raw material mixture by a rolling granulation method, a stirring granulation method, an extrusion method, a spraying method, or a press molding method, in which the carbon concentration of the granulated particles for use as cold storage material particles is 0.001% by weight to 50% by weight, and the relative density of the granulated particles for use as cold storage material particles is 10% to 50%. [Brief description of the drawings]

[0017] [Figure 1] FIG. 2 is a schematic cross-sectional view of a granulated particle for use as a cold storage material particle according to the first embodiment. [Diagram 2] FIG. 11 is a schematic cross-sectional view showing the configuration of a main part of a cold storage material particle according to a second embodiment and a refrigerator according to a fourth embodiment. [Diagram 3] FIG. 11 is a cross-sectional view showing a schematic configuration of a cryopump according to a fifth embodiment. [Figure 4] FIG. 13 is a perspective view showing a schematic configuration of a superconducting magnet according to a sixth embodiment. [Diagram 5] FIG. 13 is a cross-sectional view showing a schematic configuration of a nuclear magnetic resonance imaging apparatus according to a seventh embodiment. [Figure 6] FIG. 13 is a cross-sectional view showing a schematic configuration of a nuclear magnetic resonance spectrometer according to an eighth embodiment. [Figure 7] FIG. 13 is a perspective view showing a schematic configuration of a magnetic field application type single crystal pulling apparatus according to a ninth embodiment. [Figure 8] FIG. 23 is a schematic diagram showing a schematic configuration of a helium recondensation device according to a tenth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the same reference numerals will be used to designate the same or similar components, and the description of components that have already been described may be omitted as appropriate.

[0019] In this specification, the term "extremely low temperature" refers to a temperature range in which the superconducting phenomenon can be utilized industrially in a useful manner, for example, a temperature range of 20K or lower.

[0020] (First embodiment) The granulated particles for the regenerator particles of the first embodiment contain a rare earth oxysulfide containing at least one rare earth element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu), or a rare earth oxide containing the at least one rare earth element, and carbon having a concentration of 0.001% by weight or more and 50% by weight or less, and have a relative density of 10% to 50%.

[0021] FIG. 1 is a schematic cross-sectional view of a granulated particle for use as a cold storage material particle according to the first embodiment.

[0022] The granulated particles 101 for cold storage material particles of the first embodiment are granulated particles for producing cold storage material particles. For example, the granulated particles 101 for cold storage material particles of the first embodiment are subjected to a heat treatment for degreasing and a heat treatment for sintering, thereby producing cold storage material particles. After the heat treatment for degreasing and before the heat treatment for sintering, the granulated particles 101 for cold storage material particles may be subjected to a heat treatment for sulfurization.

[0023] The granulated particles 101 for cold storage material particles according to the first embodiment include, for example, raw material powder 101a, a binder 101b, and voids 101c, as shown in Fig. 1. The granulated particles 101 for cold storage material particles may include, for example, a dispersion medium instead of the binder 101b. The granulated particles 101 for cold storage material particles may include, for example, a gelling agent instead of the binder 101b. The raw material powder 101a may include, for example, a sintering aid for promoting sintering when producing cold storage material particles.

[0024] The granulated particles 101 for cold storage material particles are formed by granulating raw material powder 101a. The granulated particles 101 for cold storage material particles are formed, for example, by binding a plurality of raw material powders 101a with a binder 101b.

[0025] The granulated particles 101 for cold storage material particles are, for example, gel. The granulated particles 101 for cold storage material particles are formed, for example, by gelling a plurality of raw material powders 101a using a gelling agent (gelling solution). The raw material powders 101a are, for example, in a state in which they have lost their independent mobility and are aggregated and solidified.

[0026] When the granulated particles 101 for use as cold storage material particles are a gel, the granulated particles 101 for use as cold storage material particles contain, for example, raw material powder 101a and a dispersion medium. The dispersion medium contains, for example, a gelling agent. When the granulated particles 101 for use as cold storage material particles are a gel, the granulated particles 101 for use as cold storage material particles contain, for example, raw material powder 101a and a gelling agent. Note that the gelling agent that has gelled after the granulated particles 101 for use as cold storage material particles are gelled is also referred to as a gelling agent.

[0027] The raw material powder 101a contains a rare earth oxysulfide or a rare earth oxide. The rare earth oxysulfide contained in the raw material powder 101a contains at least one rare earth element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). Furthermore, the rare earth oxide contained in the raw material powder 101a includes at least one rare earth element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).

[0028] The rare earth oxysulfide contained in the raw material powder 101a is, for example, gadolinium oxysulfide or holmium oxysulfide. The rare earth oxysulfide contained in the raw material powder 101a is, for example, Gd2O2S, Tb2O2S, Dy2O2S, or Ho2O2S.

[0029] The rare earth oxide contained in the raw material powder 101a is, for example, gadolinium oxide or holmium oxide, Gd2O3, Tb2O3, Dy2O3, or Ho2O3.

[0030] The raw material powder 101a includes, for example, a carbonate, an oxide, a nitride, or a carbide containing a Group 1 element.The raw material powder 101a includes, for example, a carbonate, an oxide, a nitride, or a carbide containing a Group 2 element.

[0031] The raw material powder 101a contains, for example, a carbonate, an oxide, a nitride, or a carbide containing an additive element, which is at least one element selected from the group consisting of manganese (Mn), aluminum (Al), iron (Fe), copper (Cu), nickel (Ni), cobalt (Co), zirconium (Zr), yttrium (Y), and boron (B).

[0032] When the raw material powder 101a contains a sintering aid, the sintering aid is, for example, an oxide, such as aluminum oxide (alumina), magnesium oxide, yttrium oxide, zirconium oxide, or boron oxide.

[0033] The binder 101b is an organic material. The binder 101b is, for example, a resin. The binder 101b is, for example, polyvinyl alcohol, polyvinyl butyral, carboxymethyl cellulose, an acrylic resin, or polyethylene glycol.

[0034] When the granulated particles 101 for cold storage material particles contain a dispersion medium, the dispersion medium is an organic substance. The dispersion medium is, for example, an alginate. The dispersion medium is, for example, sodium alginate, ammonium alginate, or potassium alginate.

[0035] The relative density of the granulated particles 101 for use as cold storage material particles is 10% or more and 50% or less.

[0036] For example, when the relative density of the granulated particles 101 for cold storage material particles is low, the volume ratio of the raw material powder 101a in the granulated particles 101 for cold storage material particles is relatively small. When the relative density of the granulated particles 101 for cold storage material particles is low, the volume ratio of the binder 101b, the dispersion medium, or the voids 101c in the granulated particles 101 for cold storage material particles is relatively high.

[0037] On the other hand, when the relative density of the granulated particles 101 for cold storage material particles is high, the volume ratio of the raw material powder 101a in the granulated particles 101 for cold storage material particles is relatively high. When the relative density of the granulated particles 101 for cold storage material particles is high, the volume ratio of the binder 101b, the dispersion medium, or the voids 101c in the granulated particles 101 for cold storage material particles is relatively low.

[0038] The relative density of the granulated particles 101 for use as cold storage material particles can be calculated, for example, by dividing the average compact density obtained from 50 granulated particles by the true density of the constituent substances. The average compact density of 50 particles is calculated by dividing the weight of 50 granulated particles by the volume. The volume can be calculated by integrating the volumes of each particle, which are calculated assuming that the circle-equivalent diameter of each particle is the diameter of the particle.

[0039] In calculating the true density of the granulated particles 101 for use as cold storage material particles, first, the crystal phase of the raw material powder 101a constituting the granulated particles is identified by X-ray diffraction measurement. Then, the composition ratio of the raw material powder 101a constituting the granulated particles is obtained by Rietveld analysis or inductively coupled plasma atomic emission spectrometry of the X-ray diffraction pattern. The true density of the granulated particles 101 for use as cold storage material particles can be calculated from the crystal phase of the raw material powder 101a and the composition ratio of the raw material powder 101a.

[0040] The granulated particles 101 for use as cold storage material particles have a particle size of, for example, 50 μm or more and 7 mm or less. The aspect ratio of the granulated particles 101 for use as cold storage material particles is, for example, 1 or more and 5 or less. The aspect ratio of the granulated particles 101 for use as cold storage material particles is the ratio of the major axis to the minor axis of the granulated particles 101 for use as cold storage material particles. The shape of the granulated particles 101 for use as cold storage material particles is, for example, spherical.

[0041] In this specification, the particle diameter of the granulated particles 101 for use as cold storage material particles is a circle-equivalent diameter. The circle-equivalent diameter is the diameter of a perfect circle equivalent to the area of ​​a figure observed in an image such as an optical microscope image or a scanning electron microscope image (SEM image). The particle diameter of the granulated particles 101 for use as cold storage material particles can be determined, for example, by image analysis of the optical microscope image or the SEM image.

[0042] The granulated particles 101 for cold storage material particles contain carbon. The concentration of carbon contained in the granulated particles 101 for cold storage material particles is 0.001% by weight or more and 50% by weight or less.

[0043] Carbon is contained in, for example, the binder 101b or the dispersion medium. For example, when the relative density of the granulated particles 101 for cold storage material particles is low, the concentration of carbon is relatively high. For example, when the relative density of the granulated particles 101 for cold storage material particles is high, the concentration of carbon is relatively low.

[0044] The granulated particles 101 for cold storage material particles contain, for example, a Group 1 element. The Group 1 element is, for example, at least one element selected from the group consisting of lithium (Li), sodium (Na), and potassium (K).

[0045] The Group 1 element is contained in, for example, the raw material powder 101a, the binder 101b, or the dispersion medium. The Group 1 element is derived from, for example, a gelling solution used in producing the granulated particles 101 for the cold storage material particles.

[0046] The concentration of the Group 1 element contained in the granulated particles 101 for cold storage material particles is, for example, 0.001 atomic % or more and 60 atomic % or less.

[0047] The granulated particles 101 for cold storage material particles contain, for example, a Group 2 element. The Group 2 element is, for example, at least one element selected from the group consisting of magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba).

[0048] The Group 2 element is contained in, for example, the raw material powder 101a, the binder 101b, or the dispersion medium. The Group 2 element is derived from, for example, a gelling solution used in producing the granulated particles 101 for the cold storage material particles.

[0049] The concentration of the Group 2 element contained in the granulated particles 101 for cold storage material particles is, for example, 0.001 atomic % or more and 60 atomic % or less.

[0050] The granulated particles 101 for use as cold storage material particles contain an additive element, which is at least one element selected from the group consisting of manganese (Mn), aluminum (Al), iron (Fe), copper (Cu), nickel (Ni), cobalt (Co), zirconium (Zr), yttrium (Y), and boron (B).

[0051] The additive element is contained in, for example, the raw material powder 101a, the binder 101b, or the dispersion medium. The additive element is derived from, for example, a gelling solution used in producing the granulated particles 101 for the cold storage material particles.

[0052] The concentration of the additive element contained in the granulated particles 101 for cold storage material particles is, for example, 0.001 atomic % or more and 60 atomic % or less.

[0053] The detection of elements contained in the granulated particles 101 for cold storage material particles and the measurement of the atomic concentration of the elements can be performed, for example, by dissolving the granulated particles in a liquid and using inductively coupled plasma atomic emission spectroscopy (ICP-AES). Also, it can be performed using energy dispersive X-ray spectroscopy (EDX) or wavelength dispersive X-ray spectroscopy (WDX).

[0054] The method for producing the granulated particles for the cold storage material particles of the first embodiment is not particularly limited, but can be produced, for example, by mixing raw material powder and a binder using a ball mill or the like to prepare a raw material mixture, and then forming (granulating) the obtained raw material mixture into particles by a rolling granulation method, an agitation granulation method, an extrusion method, a spray method, a press molding method, or the like.

[0055] In the above granulation method, the strength of the granulated particles is improved by adding a binder to adhere the raw material powders to each other. For example, polyvinyl alcohol, polyvinyl butyral, carboxymethyl cellulose, acrylic resin, polyethylene glycol, etc. can be used as the binder. The amount of the binder added is, for example, 0.01% by weight or more and 40% by weight or less. For example, by increasing the amount of the binder, the breaking strength can be improved even if the relative density is low.

[0056] The raw material powder may be an oxide or an oxysulfide, and the type and ratio of the oxide or oxysulfide are adjusted according to the target composition of the regenerator particles.

[0057] The raw material powder may be a carbonate, oxide, nitride, or carbide containing a Group 1 element, Group 2 element, or additive element. The additive element is at least one element selected from the group consisting of manganese (Mn), aluminum (Al), iron (Fe), copper (Cu), nickel (Ni), cobalt (Co), zirconium (Zr), yttrium (Y), and boron (B). By using a carbonate, oxide, nitride, or carbide containing a Group 1 element, Group 2 element, or additive element as the raw material powder, granulated particles for use as heat accumulating material particles containing a Group 1 element, Group 2 element, or additive element can be produced.

[0058] The raw material mixture may contain a sintering aid as a raw material powder, such as aluminum oxide (alumina), magnesium oxide, yttrium oxide, zirconium oxide, or boron oxide.

[0059] In the rolling granulation, for example, the relative density of the granulated particles for the cold storage material particles can be changed by controlling the rotation speed and diameter of the granulator during granulation. If the rotation speed is slow or the diameter of the granulator is small, the energy during rolling decreases, and the relative density of the granulated particles for the cold storage material particles decreases.

[0060] In the manufacturing of the granulated particles for the cold storage material particles of the first embodiment, the raw material powder may be added to an alginic acid aqueous solution, mixed to prepare a slurry, and then dropped into a gelling solution to gel the slurry, thereby forming granules. This method is a method for forming granules by promoting gelation through a crosslinking reaction caused by polyvalent metal ions contained in the gelling solution.

[0061] The relative density of the granulated particles for cold storage material particles can be changed by changing the ratio of the raw material powder to the alginic acid aqueous solution. The weight ratio of the raw material powder to the alginic acid aqueous solution is, for example, 0.1 to 20 times.

[0062] The granulated particles for use as cold storage material particles are solidified into granules by gelation of the alginate. Therefore, the strength of the granulated particles, i.e., the gelling strength, varies depending on the amount of alginate contained in the particles or the viscosity of the alginate aqueous solution. For example, by adjusting the viscosity of the alginate aqueous solution, the alginate can secure the raw material powder in the gel, maintain the strength of the granulated particles for use as cold storage material particles, and obtain granulated particles for use as cold storage material particles having the desired shape.

[0063] The slurry can be dropped into the gelling solution using, for example, a dropper, a burette, a pipette, a syringe, a dispenser, an inkjet, etc. Hereinafter, this method for granulating particles is referred to as the alginic acid gel method.

[0064] In the alginate gel method, the particle size and aspect ratio of the granulated particles for the cold storage material particles can be changed by adjusting the viscosity of the slurry, the diameter of the discharge port during dropping, or the distance between the tip of the discharge port and the liquid surface of the gelling solution. The diameter of the discharge port is, for example, 50 μm or more and 3000 μm or less. The distance between the tip of the discharge port and the liquid surface of the gelling solution is, for example, 0.1 mm or more and 1000 mm or less.

[0065] When a dispenser is used for discharging, any of an air pulse type dispenser, a plunger type dispenser, and a piezoelectric type dispenser may be used as the device.

[0066] Inkjet printers are largely divided into continuous and on-demand types based on the ejection method, but any of these ejection methods may be used. In addition, on-demand printers are divided into three types: piezo, thermal, and valve, but any of these methods may be used.

[0067] The slurry dropped into the gelling solution using a dropper, burette, pipette, syringe, dispenser, inkjet, etc., is gelled by being held in the gelling solution. By gelling the slurry, granulated particles containing the raw material powder of the cold storage material are formed. The retention time of the slurry in the gelling solution is, for example, 10 minutes or more and 48 hours or less. If the gelling time is short, the gelling does not proceed sufficiently, and the strength of the granulated particles is reduced.

[0068] The alginic acid aqueous solution used in the alginic acid gel method is, for example, a sodium alginate aqueous solution, an ammonium alginate aqueous solution, or a potassium alginate aqueous solution. By using a sodium alginate aqueous solution or a potassium alginate aqueous solution containing a Group 1 element, sodium (Na) or potassium (K) can be contained in the granulated particles 101 for cold storage material particles. By using a mixed aqueous solution of a sodium alginate aqueous solution and a potassium alginate aqueous solution as a slurry, sodium (Na) and potassium (K) can be simultaneously contained in the granulated particles 101 for cold storage material particles.

[0069] The concentration of the alginate is, for example, 0.1% by weight or more and 5% by weight or less as an alginate aqueous solution. If the concentration of the alginate aqueous solution is lower than 0.1% by weight, a gel with sufficient strength cannot be formed, and granulated particles for use as cold storage material particles cannot be obtained.

[0070] As the gelling solution, for example, an aqueous solution of calcium lactate, an aqueous solution of calcium chloride, an aqueous solution of manganese (II) chloride, an aqueous solution of magnesium sulfate, an aqueous solution of beryllium sulfate, an aqueous solution of strontium nitrate, an aqueous solution of barium chloride, an aqueous solution of barium hydroxide, an aqueous solution of aluminum chloride, an aqueous solution of aluminum nitrate, an aqueous solution of aluminum lactate, an aqueous solution of iron (II) chloride, an aqueous solution of iron (III) chloride, an aqueous solution of copper (II) chloride, an aqueous solution of nickel (II) chloride, or an aqueous solution of cobalt (II) chloride can be used.

[0071] By using an aqueous solution of calcium lactate, an aqueous solution of calcium chloride, an aqueous solution of manganese (II) chloride, an aqueous solution of magnesium sulfate, an aqueous solution of beryllium sulfate, an aqueous solution of strontium nitrate, an aqueous solution of barium chloride, an aqueous solution of barium hydroxide, an aqueous solution of aluminum chloride, an aqueous solution of aluminum nitrate, an aqueous solution of aluminum lactate, an aqueous solution of iron (II) chloride, an aqueous solution of iron (III) chloride, an aqueous solution of copper (II) chloride, an aqueous solution of nickel (II) chloride, or an aqueous solution of cobalt (II) chloride in the gelling solution, calcium (K), manganese (Mn), magnesium (Mg), beryllium (Be), strontium (Sr), barium (Ba), aluminum (Al), iron (Fe), copper (Cu), nickel (Ni), or cobalt (Co) can be contained in the granulated particles 101 for the cold storage material particles.

[0072] In addition, by using an aluminum chloride aqueous solution, an aluminum nitrate aqueous solution, an aluminum lactate aqueous solution, an iron (II) chloride aqueous solution, an iron (III) chloride aqueous solution, a copper (II) chloride aqueous solution, a nickel (II) chloride aqueous solution, or a cobalt (II) chloride aqueous solution as a gelling solution, aluminum (Al), iron (Fe), copper (Cu), nickel (Ni), or cobalt (Co) can be contained in the granulated particles 101 for the cold storage material particles.

[0073] Since gelation proceeds through a crosslinking reaction caused by the polyvalent metal ions contained in the gelling solution, when an aqueous solution containing a group 1 element is used for the slurry and an aqueous solution containing an element that forms polyvalent metal ions in the aqueous solution is used for the gelling solution, the amount of group 1 element contained in the particles and the amount of element that forms polyvalent metal ions in the aqueous solution can be adjusted by adjusting the immersion time in the gelling solution of the particles granulated by dropping them into the gelling solution.

[0074] Examples of elements that form multivalent ions in an aqueous solution include calcium (Ca), manganese (Mn), magnesium (Mg), beryllium (Be), strontium (Sr), barium (Ba), aluminum (Al), iron (Fe), copper (Cu), nickel (Ni), and cobalt (Co).

[0075] At least two types of aqueous solutions containing different metal elements selected from the group consisting of calcium lactate aqueous solution, calcium chloride aqueous solution, manganese (II) chloride aqueous solution, magnesium sulfate aqueous solution, beryllium sulfate aqueous solution, strontium nitrate aqueous solution, barium chloride aqueous solution, barium hydroxide aqueous solution, aluminum chloride aqueous solution, aluminum nitrate aqueous solution, aluminum lactate aqueous solution, iron (II) chloride aqueous solution, iron (III) chloride aqueous solution, copper (II) chloride aqueous solution, nickel (II) chloride aqueous solution, and cobalt (II) chloride aqueous solution are mixed and used as a gelling solution, whereby two or more types of elements that form multivalent ions in an aqueous solution can be contained in the granulated particles 101 for cold storage material particles.

[0076] Next, the action and effect of the granulated particles for cold storage material particles of the first embodiment will be described.

[0077] The granulated particles for cold storage material particles are subjected to a heat treatment for degreasing and a heat treatment for sintering to manufacture the cold storage material particles. For example, when the granulated particles for cold storage material particles contain raw material powder of oxide, the granulated particles for cold storage material particles may be subjected to a heat treatment for sulfurization after the heat treatment for degreasing and before the heat treatment for sintering.

[0078] By degreasing the granulated particles for the cold storage material particles, a certain amount of organic components contained in the binder and the dispersion medium can be removed. For example, when the raw material powder is an oxide, if the degreasing is insufficient, the sulfurization of the oxide does not proceed sufficiently, and the required amount of oxysulfide cannot be generated.

[0079] Furthermore, if the granulated particles for the cold storage material particles are not sufficiently degreased and a large amount of organic components remain, the sintering reaction is also inhibited. If the sintering reaction is inhibited, the density of the cold storage material particles after sintering will be low. If the density of the cold storage material particles is low, the strength of the cold storage material particles will be weakened and there is a risk of them breaking during use in a refrigerator. If the sintering reaction is inhibited, the specific heat of the cold storage material particles after sintering will be low. If the specific heat of the cold storage material particles is low, the performance of the refrigerator will be reduced.

[0080] On the other hand, if the degreasing of the granulated particles for use as the cold storage material particles proceeds too far, the organic components necessary for ensuring the strength are lost, and as a result, the strength of the granulated particles after degreasing decreases, and there is a risk that the granulated particles may crack or chip.

[0081] The granulated particles 101 for use as cold storage material particles in the first embodiment have a relative density of 10% or more and 50% or less.

[0082] By setting the relative density of the granulated particles 101 for cold storage material particles to 50% or less, it is easy to remove organic components contained in the binder and the dispersion medium during the heat treatment for degreasing. Therefore, for example, the temperature of the heat treatment for degreasing can be reduced, or the time of the heat treatment for degreasing can be shortened. Also, for example, the temperature of the heat treatment for sulfurization can be reduced, or the time of the heat treatment for sulfurization can be shortened. Also, for example, the temperature of the heat treatment for sintering can be reduced, or the time of the heat treatment for sintering can be shortened. Therefore, according to the granulated particles 101 for cold storage material particles of the first embodiment, the manufacturing cost of the cold storage material particles can be reduced by reducing the temperature of the heat treatment or the time of the heat treatment.

[0083] From the viewpoint of reducing the temperature of the heat treatment for degreasing, sulfurizing, or sintering, or from the viewpoint of reducing the time of the heat treatment for degreasing, sulfurizing, or sintering, the relative density of the granulated particles 101 for the cold storage material particles is preferably 45% or less, and more preferably 40% or less.

[0084] If the relative density of the granulated particles for use as cold storage material particles is less than 10%, for example, the proportion of voids in the cold storage material particles increases, and the strength of the granulated particles for use as cold storage material particles decreases. If the strength of the granulated particles for use as cold storage material particles decreases, the handling of the granulated particles for use as cold storage material particles becomes difficult.

[0085] Furthermore, if the relative density of the granulated particles for the cold storage material particles is less than 10%, there is a risk that an excessive amount of organic components will be removed during the heat treatment for degreasing, which will result in a decrease in the strength and specific heat of the produced cold storage material particles.

[0086] In addition, when the relative density of the granulated particles for cold storage material particles is less than 10%, for example, the relative density of the manufactured cold storage material particles decreases, and the specific heat of the cold storage material particles decreases. This is thought to be because the number of contact points between the raw material powders decreases, and the sinterability of the cold storage material particles decreases.

[0087] By setting the relative density of the granulated particles 101 for use as cold storage material particles of the first embodiment to 10% or more, the strength of the granulated particles 101 for use as cold storage material particles is maintained, and the granulated particles for use as cold storage material particles become easy to handle.

[0088] In addition, by making the relative density of the granulated particles 101 for cold storage material particles 100 10% or more, excessive removal of organic components during the heat treatment for degreasing is suppressed, and therefore, the decrease in strength and specific heat of the cold storage material particles produced is suppressed.

[0089] Furthermore, by setting the relative density of the granulated particles 101 for cold storage material particles to 10% or more, the sintering property of the cold storage material particles to be manufactured is improved, and the specific heat of the cold storage material particles is improved.

[0090] From the viewpoint of maintaining the strength of the granulated particles 101 for cold storage material particles, the relative density of the granulated particles 101 for cold storage material particles is preferably 15% or more, and more preferably 20% or more. From the viewpoint of suppressing excessive removal of organic components during the heat treatment for degreasing, the relative density of the granulated particles 101 for cold storage material particles is preferably 15% or more, and more preferably 20% or more. From the viewpoint of improving the sinterability of the cold storage material particles to be produced, the relative density of the granulated particles 101 for cold storage material particles is preferably 15% or more, and more preferably 20% or more.

[0091] The granulated particles 101 for use as cold storage material particles in the first embodiment contain carbon at a concentration of 0.001% by weight or more and 50% by weight or less.

[0092] When the carbon concentration of the granulated particles for use as cold storage material particles is high, the strength of the granulated particles for use as cold storage material particles is improved. For example, when the carbon concentration of the granulated particles for use as cold storage material particles is less than 0.001% by weight, the strength of the granulated particles for use as cold storage material particles is reduced, making handling difficult.

[0093] On the other hand, if the carbon concentration of the granulated particles for cold storage material particles is high, the thermal conductivity of the cold storage material particles produced from the granulated particles for cold storage material particles decreases because excess carbon remains at the crystal grain boundaries of the cold storage material particles produced.

[0094] The granulated particles 101 for use as cold storage material particles of the first embodiment have a carbon concentration of 0.001% by weight or more, which improves the strength of the granulated particles for use as cold storage material particles. From the viewpoint of improving the strength of the granulated particles for use as cold storage material particles, the carbon concentration of the granulated particles 101 for use as cold storage material particles is preferably 0.01% by weight or more, and more preferably 0.1% by weight or more.

[0095] The granulated particles 101 for cold storage material particles of the first embodiment have a carbon concentration of 50% by weight or less, which improves the thermal conductivity of the cold storage material particles produced. From the viewpoint of improving the thermal conductivity of the cold storage material particles produced, the carbon concentration of the granulated particles 101 for cold storage material particles is preferably 10% by weight or less, and more preferably 5% by weight or less.

[0096] The granulated particles 101 for cold storage material particles of the first embodiment preferably contain a Group 1 element with a concentration of 0.001 atomic % or more and 60 atomic % or less. By containing a Group 1 element in the above concentration range, the granulated particles 101 for cold storage material particles can improve the sintering property of the cold storage material particles to be manufactured. Therefore, for example, the strength and specific heat of the cold storage material particles to be manufactured are improved.

[0097] From the viewpoint of improving the sinterability of the produced cold storage material particles, the concentration of the Group 1 element contained in the granulated particles 101 for cold storage material particles is more preferably 0.01 atomic % or more and 30 atomic % or less, and even more preferably 0.1 atomic % or more and 10 atomic % or less.

[0098] The granulated particles 101 for cold storage material particles of the first embodiment preferably contain a Group II element with a concentration of 0.001 atomic % or more and 60 atomic % or less. By containing a Group II element in the above concentration range, the granulated particles 101 for cold storage material particles can improve the sintering property of the cold storage material particles to be manufactured. Therefore, for example, the strength and specific heat of the cold storage material particles to be manufactured are improved.

[0099] From the viewpoint of improving the sinterability of the produced cold storage material particles, the concentration of the Group 2 element contained in the granulated particles 101 for cold storage material particles is more preferably 0.01 atomic % or more and 30 atomic % or less, and even more preferably 0.1 atomic % or more and 10 atomic % or less.

[0100] The granulated particles 101 for cold storage material particles of the first embodiment preferably contain an additive element that is at least one element selected from the group consisting of manganese (Mn), aluminum (Al), iron (Fe), copper (Cu), nickel (Ni), cobalt (Co), zirconium (Zr), yttrium (Y), and boron (B) at a concentration of 0.001 atomic % or more and 60 atomic % or less. The granulated particles 101 for cold storage material particles contain an additive element in the above concentration range, thereby improving the sinterability of the cold storage material particles to be manufactured. Therefore, for example, the strength and specific heat of the cold storage material particles to be manufactured are improved.

[0101] From the viewpoint of improving the sinterability of the produced cold storage material particles, the concentration of the additive element contained in the granulated particles 101 for cold storage material particles is more preferably 0.01 atomic % or more and 30 atomic % or less, and even more preferably 0.1 atomic % or more and 10 atomic % or less.

[0102] The granulated particles 101 for cold storage material particles of the first embodiment preferably contain aluminum oxide (alumina), magnesium oxide, yttrium oxide, zirconium oxide, or boron oxide. The above oxides function as sintering aids. By containing the above oxides, the granulated particles 101 for cold storage material particles can improve the sinterability of the cold storage material particles to be produced.

[0103] As described above, according to the first embodiment, it is possible to provide granulated particles for cold storage material particles that can reduce the manufacturing cost of cold storage material particles.

[0104] Second Embodiment The cold storage material particles of the second embodiment are obtained by sintering the granulated particles for cold storage material particles of the first embodiment.

[0105] The cold storage material particles of the second embodiment have a particle size of, for example, 50 μm or more and 5 mm or less. The aspect ratio of the cold storage material particles is, for example, 1 or more and 5 or less. The aspect ratio of the cold storage material particles is the ratio of the major axis to the minor axis of the cold storage material particles. The shape of the cold storage material particles is, for example, spherical. The cold storage material particles of the second embodiment have a relative density of, for example, 90% or more. The relative density of the cold storage material particles of the second embodiment is preferably 93% or more, and more preferably 95% or more.

[0106] The cold storage material particles of the second embodiment are cold storage material particles obtained from the granulated particles for cold storage material particles of the first embodiment. The cold storage material particles of the second embodiment contain rare earth oxysulfide or rare earth oxide. The rare earth oxysulfide contained in the cold storage material particles contains at least one rare earth element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). The rare earth oxide contained in the regenerator particles contains at least one rare earth element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).

[0107] The maximum value of the volumetric specific heat of the cold storage material particles in the second embodiment in the temperature range of 2 K to 10 K is, for example, 0.5 J / (cm 3 ·K) or higher.

[0108] The cold storage material particles of the second embodiment may be, for example, a compound represented by the general formula R 2±0.1 O2S 1±0.1 (wherein R represents at least one rare earth element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu).

[0109] In the rare earth oxysulfide represented by the above general formula, the maximum volumetric specific heat and the temperature at which the maximum volumetric specific heat is shown vary depending on the selected rare earth element. Therefore, the specific heat characteristics of the rare earth oxysulfide can be adjusted by appropriately adjusting the ratio of the rare earth element. The rare earth element is, for example, at least one element selected from the group consisting of Gd, Tb, Dy, Ho, and Er. The rare earth element may include, for example, two or more kinds of rare earth elements.

[0110] The cold storage material particles of the second embodiment may be, for example, a compound represented by the general formula R 1±0.1 M 1±0.1 O 3±0.1 (wherein R represents at least one element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, and M represents at least one element selected from the group consisting of Al, Cr, Mn, and Fe).

[0111] In the rare earth oxide represented by the above general formula, the maximum volumetric specific heat and the temperature at which the maximum volumetric specific heat is shown vary depending on the rare earth element selected. Therefore, the specific heat characteristics of the rare earth oxide can be adjusted by appropriately adjusting the ratio of the rare earth element. The rare earth element is, for example, at least one element selected from the group consisting of Gd, Tb, Dy, Ho, and Er. The rare earth element may include, for example, two or more kinds of rare earth elements.

[0112] The cold storage material particles of the second embodiment contain at least one element selected from the group consisting of aluminum (Al), magnesium (Mg), iron (Fe), copper (Cu), nickel (Ni), cobalt (Co), zirconium (Zr), and yttrium (Y). The above element is, for example, an element derived from the sintering aid contained in the granulated particles 101 for cold storage material particles of the first embodiment.

[0113] The cold storage material particles of the second embodiment contain, for example, boron (B). The boron (B) is derived from, for example, the sintering aid contained in the granulated particles 101 for cold storage material particles of the first embodiment.

[0114] The cold storage material particles of the second embodiment contain, as an oxide, a substance derived from the sintering aid of the granulated particles 101 for cold storage material particles of the first embodiment. The oxide is, for example, aluminum oxide (alumina), magnesium oxide, yttrium oxide, zirconium oxide, or boron oxide.

[0115] The cold storage material particles of the second embodiment contain at least one element selected from the group consisting of aluminum (Al), magnesium (Mg), iron (Fe), copper (Cu), nickel (Ni), cobalt (Co), zirconium (Zr), yttrium (Y), and boron (B) in an amount of 0.01 atomic % or more and 20 atomic % or less.

[0116] The above elements constituting the sintering aid do not exhibit specific heat properties, so if the amount of the above elements added exceeds 20 atomic % in the cold storage material particles, the volumetric specific heat of the cold storage material particles decreases, the cold storage performance of the cold storage unit decreases, and the refrigeration capacity of the refrigerator decreases.

[0117] The cold storage material particles of the second embodiment have a volumetric specific heat of 0.5 J / (cm 3 ·K) or more. The cold storage material particles of the second embodiment have a volumetric specific heat of 0.55 J / (cm) in the temperature range of 2 K to 8 K. 3 ·K) or more. The cold storage material particles of the second embodiment have a volumetric specific heat of, for example, 0.6 J / (cm 3 ·K) or higher.

[0118] The cold storage material particles of the second embodiment have a maximum volumetric specific heat of 0.5 J / (cm 3 ·K) or more. Therefore, the cold storage material particles of the second embodiment have a high volumetric specific heat. Since the cold storage material particles of the second embodiment have a high volumetric specific heat, a cold storage device equipped with the cold storage material particles of the second embodiment has high cold storage performance, and the refrigerator exhibits high refrigeration capacity.

[0119] The particle size of the cold storage material particles in the second embodiment is, for example, 50 μm or more and 5 mm or less. The particle size of the cold storage material particles is preferably 1 mm or less, and more preferably 500 μm or less. When the particle size of the cold storage material particles exceeds the above lower limit, the packing density of the cold storage material particles in the cold storage unit is lowered, the pressure loss of the working medium such as helium is reduced, and the refrigeration performance of the refrigerator is improved. On the other hand, when the particle size of the cold storage material particles is below the above upper limit, the distance from the surface of the cold storage material particle to the center of the particle is shortened, and heat transfer between the working medium and the cold storage material particles is easily transmitted to the center of the cold storage material, and the refrigeration performance of the refrigerator is improved.

[0120] The particle size of the granulated particles for use as cold storage material particles is the circle-equivalent diameter. The circle-equivalent diameter is the diameter of a perfect circle equivalent to the area of ​​a figure observed in an image such as an optical microscope image or a scanning electron microscope image (SEM image). The particle size of the granulated particles for use as cold storage material particles can be determined, for example, by image analysis of the optical microscope image or the SEM image.

[0121] The cold storage material particles of the second embodiment have a relative density of, for example, 90% or more. The cold storage material particles of the second embodiment preferably have a relative density of 93% or more, and more preferably have a relative density of 95% or more.

[0122] The relative density of the cold storage material particles in the second embodiment can be calculated by dividing the average sintered density obtained from 50 cold storage material particles by the true density of the constituent materials. The average sintered density of 50 particles is calculated by dividing the weight of 50 cold storage material particles by the volume. The volume can be calculated by integrating the volumes of each particle, which are obtained by assuming that the circle-equivalent diameter of each particle is the diameter of the particle.

[0123] The crystal structure of the rare earth oxysulfide contained in the cold storage material particles of the second embodiment is, for example, Ce2O2S type, and its space group is P-3m. The crystal structure can be confirmed by powder X-ray diffraction measurement, observation of an electron beam backscatter diffraction image using a scanning electron microscope, or observation using a transmission electron microscope.

[0124] The crystal structure of the rare earth oxide contained in the cold storage material particles of the second embodiment is, for example, a perovskite type, and its space group is, for example, Pnma. The space group is, for example, Pm-3m. The crystal structure and space group can be confirmed by powder X-ray diffraction measurement, observation of an electron beam backscatter diffraction image using a scanning electron microscope, or observation using a transmission electron microscope.

[0125] The cold storage material particles of the second embodiment are manufactured by subjecting the granulated particles 101 for cold storage material particles of the first embodiment to a heat treatment for degreasing and a heat treatment for sintering. For example, when the granulated particles for cold storage material particles contain raw material powder of oxides, the granulated particles for cold storage material particles may be subjected to a heat treatment for sulfurization after the heat treatment for degreasing and before the heat treatment for sintering.

[0126] The degreasing heat treatment is performed, for example, in an air atmosphere. The temperature of the degreasing heat treatment is, for example, 400° C. or more and 700° C. or less. The time of the degreasing heat treatment is, for example, 30 minutes or more and 6 hours or less.

[0127] When an oxide is used as the raw powder 101a of the granulated particles 101 for cold storage material particles to manufacture cold storage material particles containing oxysulfide, the granulated particles 101 for cold storage material particles are sulfurized. In this case, heat treatment is performed in a sulfurization atmosphere. The sulfurization atmosphere contains a gas containing a sulfur atom with a negative oxidation number, such as hydrogen sulfide (H2S), carbon sulfide (CS2), or methanethiol (CH3SH). The temperature of the sulfurization heat treatment is, for example, 400°C or higher and 600°C or lower. The time of the sulfurization heat treatment is, for example, 1 hour or higher and 5 hours or lower.

[0128] The heat treatment for sintering the granulated particles after degreasing or the obtained oxysulfide is carried out, for example, in an inert gas atmosphere. The heat treatment temperature is, for example, 1100° C. or more and 2000° C. or less. The heat treatment temperature is, for example, 1200° C. or more and 1800° C. or less. The heat treatment time is, for example, 1 hour or more and 48 hours or less.

[0129] When the granulated particles 101 for cold storage material particles contain a Group 1 element, a Group 2 element, or an additive element, the sintering temperature can be lowered and the sintering time can be shortened due to the sintering promotion effect. The additive element is at least one element selected from the group consisting of manganese (Mn), aluminum (Al), iron (Fe), copper (Cu), nickel (Ni), cobalt (Co), zirconium (Zr), yttrium (Y), and boron (B).

[0130] The heat treatment for sintering the granulated particles 101 for use as cold storage material particles, which contains a Group 1 element, a Group 2 element, or an additive element, is carried out, for example, in an inert gas atmosphere. The temperature of the sintering heat treatment is, for example, 1000° C. or higher and 2000° C. or lower. The temperature of the sintering heat treatment is, for example, 1100° C. or higher and 1700° C. or lower. The time of the sintering heat treatment is, for example, 1 hour or higher and 48 hours or lower.

[0131] The cold storage material particles of the second embodiment are manufactured by sintering the granulated particles 101 for cold storage material particles of the first embodiment. Therefore, for example, the temperature of the degreasing heat treatment can be reduced or the time of the degreasing heat treatment can be shortened. Also, for example, the temperature of the sulfurizing heat treatment can be reduced or the time of the sulfurizing heat treatment can be shortened. Also, for example, the temperature of the sintering heat treatment can be reduced or the time of the sintering heat treatment can be shortened. Therefore, the manufacturing cost of the cold storage material particles of the second embodiment is reduced.

[0132] The cold storage material particles of the second embodiment are manufactured by sintering the granulated particles 101 for cold storage material particles of the first embodiment. Therefore, for example, organic components are sufficiently removed, the amount of residual carbon contained in the cold storage material particles is reduced, and the thermal conductivity of the cold storage material particles is improved. Therefore, the performance of a refrigerator using the cold storage material particles of the second embodiment is improved.

[0133] The aspect ratio of the cold storage material particles in the second embodiment is preferably, for example, from 1 to 5. The aspect ratio of the cold storage material particles is more preferably, for example, from 1 to 2. When the aspect ratio of the cold storage material particles is below the upper limit value, the voids when the cold storage material particles are filled in the cold storage unit become uniform, and the refrigeration performance of the refrigerator is improved.

[0134] As described above, according to the second embodiment, it is possible to provide cold storage material particles that can reduce the manufacturing cost.

[0135] (Third embodiment) The cold storage device of the third embodiment is a cold storage device filled with a plurality of cold storage particles of the second embodiment. For example, when the peripheral length of the projected image of the plurality of cold storage particles of the second embodiment is L and the actual area of ​​the projected image is A, the cold storage device of the third embodiment has a ratio of 4πA / L 2 The ratio of the cold storage material particles having a circularity R of 0.5 or less is 5% or less.

[0136] The circularity R can be obtained by image processing of the shapes of multiple cold storage material particles using an optical microscope. Cold storage material particles with a circularity R of 0.5 or less have a shape with unevenness on the surface. When multiple cold storage material particles containing more than 5% of such cold storage material particles are filled into a cold storage device, the porosity formed by the cold storage material particles in the cold storage device becomes non-uniform and the filling property becomes unstable, so that when the working medium flows in, the cold storage performance decreases, and the cold storage material particles move or break due to stress applied to the cold storage material particles when the cold storage material particles are filled or when the refrigerator is operated, causing clogging of the voids, thereby decreasing the refrigeration performance and long-term reliability of the refrigerator. The cold storage material particles with a circularity R of 0.5 or less are preferably 2% or less, and more preferably 0%.

[0137] (Fourth embodiment) The refrigerator of the fourth embodiment is a refrigerator including the cold storage unit of the third embodiment filled with a plurality of cold storage material particles of the second embodiment. Hereinafter, some of the contents overlapping with the second and third embodiments will be omitted.

[0138] Fig. 2 is a schematic cross-sectional view showing the main configuration of the regenerator particles of the second embodiment and the refrigerator of the fourth embodiment. Fig. 2 is a schematic cross-sectional view showing the main configuration of a GM refrigerator, which is an example of the refrigerator of the fourth embodiment, including the regenerator of the third embodiment filled with a plurality of regenerator particles of the second embodiment. The refrigerator of the fourth embodiment is a two-stage regenerator type cryogenic refrigerator 100 used for cooling superconducting equipment and the like. The regenerator filled with a plurality of regenerator particles of the second embodiment may be a Stirling type refrigerator or a pulse tube type refrigerator, in addition to the above-mentioned GM refrigerator.

[0139] The cold storage type cryogenic refrigerator 100 (refrigerator) includes a first cylinder 111, a second cylinder 112, a vacuum container 113, a first cold storage unit 114, a second cold storage unit 115 (cold storage units), a first seal ring 116, a second seal ring 117, a first cold storage material 118, a second cold storage material 119 (cold storage material particles), a first expansion chamber 120, a second expansion chamber 121, a first cooling stage 122, a second cooling stage 123, and a compressor 124.

[0140] The cold storage type cryogenic refrigerator 100 has a vacuum container 113 in which a large-diameter first cylinder 111 and a small-diameter second cylinder 112 coaxially connected to the first cylinder 111 are installed. A first cold storage unit 114 is arranged in the first cylinder 111 so as to be capable of reciprocating. A second cold storage unit 115, which is an example of the cold storage unit of the third embodiment, is arranged in the second cylinder 112 so as to be capable of reciprocating.

[0141] A first seal ring 116 is disposed between the first cylinder 111 and the first regenerator 114. A second seal ring 117 is disposed between the second cylinder 112 and the second regenerator 115.

[0142] The first regenerator 114 is filled with a first regenerator material 118 such as a Cu mesh. The second regenerator 115 is filled with a second regenerator material 119, which is a plurality of regenerator particles of the second embodiment.

[0143] The second regenerator 115 may be divided by a metal mesh material and have a plurality of regenerator packed beds. When the second regenerator 115 is divided into a plurality of packed beds, at least one packed bed is filled with a regenerator particle group consisting of a plurality of the regenerator particles of the second embodiment, and is combined with at least one type of regenerator particle group selected from, for example, a lead regenerator particle group, a bismuth regenerator particle group, a tin regenerator particle group, a holmium copper regenerator particle group, an erbium nickel regenerator particle group, an erbium cobalt regenerator particle group, and a gadolinium aluminum oxide regenerator particle group.

[0144] The combination of the heat storage materials is such that the first heat storage material particle group has a higher peak specific heat temperature, and the second heat storage material particle group has a lower peak specific heat temperature, and the combinations are made so that the peak specific heat temperatures decrease sequentially.

[0145] In the case of the two-layer type, a combination of using holmium copper cold storage material particles as the first cold storage material particle group and the cold storage material particle group according to the second embodiment as the second cold storage material particle group can be mentioned. Also, in the case of the three-layer type, a combination of using at least one cold storage material particle group selected from lead cold storage material particle group, bismuth cold storage material particle group, and tin cold storage material particle group as the first cold storage material particle group, using holmium copper cold storage material particle group as the second cold storage material particle group, and using the cold storage material particle group according to the second embodiment as the third cold storage material particle group can be mentioned.

[0146] The holmium copper regenerator particles are preferably, for example, HoCu2 or HoCu.The erbium nickel regenerator particles are preferably, for example, ErNi or Er3Ni.

[0147] The first regenerator 114 and the second regenerator 115 each have a passage for the working medium provided in the gap of the first regenerator material 118 and the second regenerator material 119. The working medium is helium gas.

[0148] A first expansion chamber 120 is provided between the first cold storage unit 114 and the second cold storage unit 115. A second expansion chamber 121 is provided between the second cold storage unit 115 and the end wall of the second cylinder 112. A first cooling stage 122 is provided at the bottom of the first expansion chamber 120. A second cooling stage 123, which has a lower temperature than the first cooling stage 122, is formed at the bottom of the second expansion chamber 121.

[0149] The two-stage regenerative cryogenic refrigerator 100 described above is supplied with a high-pressure working medium from a compressor 124. The supplied working medium passes between the first regenerator material 118 packed in the first regenerator 114 and reaches the first expansion chamber 120. Then, the working medium passes between the second regenerator material 119 packed in the second regenerator 115 and reaches the second expansion chamber 121.

[0150] At this time, the working medium is cooled by supplying thermal energy to the first cold storage material 118 and the second cold storage material 119. The working medium passing between the first cold storage material 118 and the second cold storage material 119 expands in the first expansion chamber 120 and the second expansion chamber 121 to generate cold. Then, the first cooling stage 122 and the second cooling stage 123 are cooled.

[0151] The expanded working medium flows in the opposite direction between the first cold storage material 118 and the second cold storage material 119. The working medium is discharged after receiving thermal energy from the first cold storage material 118 and the second cold storage material 119. In this process, the heat recovery effect is improved, and the thermal efficiency of the working medium cycle is improved, so that the cold storage type cryogenic refrigerator 100 is configured to realize even lower temperatures.

[0152] In the cold storage unit provided in the refrigerator of the fourth embodiment, a plurality of cold storage particles of the second embodiment are filled in the second cold storage unit 115 as the second cold storage material 119. At least a part of the second cold storage material 119 is the cold storage material particle of the second embodiment.

[0153] In the second embodiment, when the peripheral length of each projected image of the plurality of cold storage material particles is L and the actual area of ​​the projected image is A, the ratio of the peripheral length of the projected image to the actual area of ​​the plurality of cold storage material particles is 4πA / L 2It is preferable that the circularity R of 0.5 or less is 5% or less.

[0154] In order to improve the refrigeration capacity of a refrigerator, it is desirable to improve the specific heat per unit volume of the cold storage material and to improve the thermal conductivity and heat transfer coefficient. The refrigerator of the fourth embodiment is equipped with a cold storage material or cold storage material particles that maintain the volumetric specific heat and improve the thermal conductivity and heat transfer coefficient.

[0155] By using the refrigerator of the fourth embodiment in a magnetic levitation train, the long-term reliability of the magnetic levitation train can be improved.

[0156] As described above, according to the fourth embodiment, a refrigerator with excellent characteristics can be realized by using the cold storage material particles with excellent characteristics.

[0157] Fifth embodiment The cryopump of the fifth embodiment includes the refrigerator of the fourth embodiment. Hereinafter, some of the contents that overlap with the fourth embodiment will be omitted.

[0158] 3 is a cross-sectional view showing a schematic configuration of a cryopump according to the fifth embodiment. The cryopump according to the fifth embodiment is a cryopump 500 including the regenerative cryogenic refrigerator 100 according to the fourth embodiment.

[0159] The cryopump 500 includes a cryopanel 501 that condenses or adsorbs gas molecules, a regenerative cryogenic refrigerator 100 that cools the cryopanel 501 to a predetermined cryogenic temperature, a shield 503 provided between the cryopanel 501 and the regenerative cryogenic refrigerator 100, a baffle 504 provided at the intake port, and a ring 505 that changes the pumping speed of argon, nitrogen, hydrogen, etc.

[0160] According to the fifth embodiment, a cryopump with excellent characteristics can be realized by using a refrigerator with excellent characteristics. In addition, by using the cryopump of the fifth embodiment in a semiconductor manufacturing device, the long-term reliability of the semiconductor manufacturing device can be improved and the number of maintenance operations for the semiconductor manufacturing device can be reduced. As a result, this contributes to improving the quality of the semiconductors manufactured and reducing the manufacturing costs.

[0161] Sixth embodiment The superconducting magnet of the sixth embodiment includes the refrigerator of the fourth embodiment. Hereinafter, some of the contents that overlap with the fourth embodiment will be omitted.

[0162] 4 is a perspective view showing a schematic configuration of a superconducting magnet according to a sixth embodiment. The superconducting magnet according to the sixth embodiment is, for example, a superconducting magnet 600 for a magnetic levitation train, which includes the regenerative cryogenic refrigerator 100 according to the fourth embodiment.

[0163] A superconducting magnet 600 for a magnetic levitation train includes a superconducting coil 601, a liquid helium tank 602 for cooling the superconducting coil 601, a liquid nitrogen tank 603 for preventing the evaporation of the liquid helium, a laminated insulation material 605, a power lead 606, a persistent current switch 607, and a regenerative type cryogenic refrigerator 100.

[0164] According to the fifth embodiment, a superconducting magnet with excellent characteristics can be realized by using a refrigerator with excellent characteristics.

[0165] Seventh embodiment The nuclear magnetic resonance imaging apparatus of the seventh embodiment includes the refrigerator of the fourth embodiment. Hereinafter, some of the contents that overlap with the fourth embodiment will be omitted.

[0166] 5 is a cross-sectional view showing a schematic configuration of a nuclear magnetic resonance imaging apparatus according to the seventh embodiment. The nuclear magnetic resonance imaging (MRI) apparatus according to the seventh embodiment is a nuclear magnetic resonance imaging apparatus 700 including the regenerative cryogenic refrigerator 100 according to the fourth embodiment.

[0167] The nuclear magnetic resonance imaging apparatus 700 includes a superconducting static magnetic field coil 701 that applies a spatially uniform and temporally stable static magnetic field to the human body, a correction coil (not shown) that corrects non-uniformity of the generated magnetic field, a gradient magnetic field coil 702 that applies a magnetic field gradient to a measurement region, a radio frequency wave transmitting / receiving probe 703, a cryostat 705, and a radiation heat insulating shield 706. A regenerative type cryogenic refrigerator 100 is used to cool the superconducting static magnetic field coil 701.

[0168] According to the seventh embodiment, a nuclear magnetic resonance imaging apparatus with excellent characteristics can be realized by using a refrigerator with excellent characteristics.

[0169] Eighth embodiment The nuclear magnetic resonance apparatus of the eighth embodiment includes the refrigerator of the fourth embodiment. Hereinafter, some of the contents that overlap with the fourth embodiment will be omitted.

[0170] 6 is a cross-sectional view showing a schematic configuration of a nuclear magnetic resonance apparatus according to a seventh embodiment. The nuclear magnetic resonance (NMR) apparatus according to the seventh embodiment is a nuclear magnetic resonance apparatus 800 including the regenerative cryogenic refrigerator 100 according to the third embodiment.

[0171] The nuclear magnetic resonance apparatus 800 includes a superconducting static magnetic field coil 802 that applies a magnetic field to a sample such as an organic substance placed in a sample tube 801, a high-frequency oscillator 803 that applies radio waves to the sample tube 801 in the magnetic field, and an amplifier 804 that amplifies an induced current generated in a coil (not shown) around the sample tube 801. The apparatus also includes a regenerative type cryogenic refrigerator 100 that cools the superconducting static magnetic field coil 802.

[0172] According to the eighth embodiment, a nuclear magnetic resonance apparatus with excellent characteristics can be realized by using a refrigerator with excellent characteristics.

[0173] Ninth embodiment The magnetic field application type single crystal pulling apparatus of the ninth embodiment includes the refrigerator of the fourth embodiment. In the following, some of the contents that overlap with the fourth embodiment will be omitted.

[0174] 7 is a perspective view showing a schematic configuration of a magnetic field application type single crystal pulling apparatus according to the ninth embodiment. The magnetic field application type single crystal pulling apparatus according to the ninth embodiment is a magnetic field application type single crystal pulling apparatus 900 including the regenerative cryogenic refrigerator 100 according to the fourth embodiment.

[0175] The magnetic field application type single crystal pulling apparatus 900 includes a single crystal pulling section 901 having a crucible for melting raw material, a heater, a single crystal pulling mechanism, etc., a superconducting coil 902 for applying a static magnetic field to the raw material melt, a lifting mechanism 903 for the single crystal pulling section 901, a current lead 905, a heat shield plate 906, and a helium container 907. A regenerative type cryogenic refrigerator 100 is used to cool the superconducting coil 902.

[0176] According to the ninth embodiment, a magnetic field application type single crystal pulling apparatus with excellent characteristics can be realized by using a refrigerator with excellent characteristics.

[0177] (Tenth embodiment) The helium recondensing device of the tenth embodiment includes the refrigerator of the fourth embodiment. Hereinafter, some of the contents that overlap with the fourth embodiment will be omitted.

[0178] 8 is a schematic diagram showing a schematic configuration of a helium recondensing apparatus according to the tenth embodiment. The helium recondensing apparatus according to the tenth embodiment is a helium recondensing apparatus 1000 including the regenerative cryogenic refrigerator 100 according to the fourth embodiment.

[0179] The helium recondensation device 1000 includes a regenerative cryogenic refrigerator 100 , an evaporation pipe 1001 , and a liquefaction pipe 1002 .

[0180] The helium recondensation device 1000 can recondense helium gas that evaporates from a liquid helium device provided in an apparatus that uses liquid helium, such as a superconducting magnet, a nuclear magnetic resonance (NMR) device, a nuclear magnetic resonance imaging (MRI) device, a physical property measurement system (PPMS), or a magnetic property measurement system, to produce liquid helium.

[0181] Helium gas is introduced into the helium recondenser 1000 from a liquid helium device (not shown) through evaporation piping 1001. The helium gas is cooled to 4K, which is below the liquefaction temperature of helium, by the regenerative cryogenic refrigerator 100. The condensed and liquefied liquid helium passes through liquefaction piping 1002 and returns to the liquid helium device.

[0182] According to the tenth embodiment, a refrigerator with excellent characteristics is used, thereby making it possible to realize a helium recondensing device with excellent characteristics. EXAMPLES

[0183] Hereinafter, examples and comparative examples relating to the granulated particles for cold storage material particles of the first embodiment and the cold storage material particles of the second embodiment, and their evaluation results will be described.

[0184] Example 1 The Gd2O3 powder was mixed and ground in a ball mill for 24 hours to prepare a raw material mixture. The obtained raw material mixture was then dried and granulated using a rolling granulator to prepare granulated particles for use as cold storage material particles with a particle size of 0.4mm to 0.6mm. At this time, polyvinyl alcohol was used as the binder, and was added to the raw material powder at 1.2% by weight. The carbon concentration of the granulated particles for use as cold storage material particles was 0.99% by weight. The relative density of the granulated particles for use as cold storage material particles was 34%.

[0185] In order to evaluate the strength of the granulated particles for use as cold storage material particles, the granulated particles were filled into a cylindrical container with a diameter of 15 mm and a height of 5 mm. At this time, a sufficient amount of granulated particles for use as cold storage material particles was filled so that the granulated particles for use as cold storage material particles were fixed in the cylindrical container and did not move freely. The amplitude of the container was 2 mm, and the maximum acceleration was 200 m / s. 2 A simple harmonic motion of 1×10 3 As a result, the rate of broken granulated particles for use as cold storage material particles was less than 0.1% by weight.

[0186] The granulated particles for use as cold storage material particles were degreased at 600°C for 2 hours in an air atmosphere. The granulated particles for use as cold storage material particles after degreasing had a carbon concentration of 0.51% by weight and a relative density of 40%. The granulated particles for use as cold storage material particles were heat-treated at 600°C for 2 hours in an atmosphere containing hydrogen sulfide (H2S) to sulfurize the granulated particles. Thereafter, the granulated particles for use as cold storage material particles were heat-treated at 1300°C for 12 hours in an inert gas atmosphere to sinter the granulated particles for use as cold storage material particles, and cold storage material particles were produced.

[0187] The main component of the regenerator particles in Example 1 is gadolinium oxysulfide.

[0188] In the following examples and comparative examples, the mixing time of the raw material powders, the conditions of the degreasing heat treatment, the conditions of the sulfurizing heat treatment, the conditions of the sintering heat treatment, etc. are adjusted to be appropriate conditions.

[0189] Example 2 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 1, except that a mixture of Gd2O3 powder and Na2CO3 powder was used as the raw material powder.

[0190] Example 3 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 2, except that K2CO3 powder was used instead of Na2CO3 powder.

[0191] Example 4 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 2, except that CaCO3 powder was used instead of Na2CO3 powder.

[0192] Example 5 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 2, except that MgCO3 powder was used instead of Na2CO3 powder.

[0193] Example 6 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 2, except that SrCO3 powder was used instead of Na2CO3 powder.

[0194] Example 7 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 2, except that CaCO3 powder was used in addition to Na2CO3 powder.

[0195] Example 8 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 7, except that MgCO3 powder was used instead of CaCO3 powder.

[0196] Example 9 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 7, except that SrCO3 powder was used instead of CaCO3 powder.

[0197] Example 10 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 1, except that Ho2O3 powder was used instead of Gd2O3 powder.

[0198] Example 11 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 2, except that K2CO3 powder was used in addition to Na2CO3 powder.

[0199] Example 12 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 2, except that K2CO3 powder and CaCO3 powder were used in addition to Na2CO3 powder.

[0200] (Examples 13 to 15) Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 2, except that the weight of the Na2CO3 powder was changed.

[0201] (Examples 16 to 18) Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 7, except that the weight of the CaCO3 powder was changed.

[0202] (Example 19) Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 2, except that a part of the Gd2O3 powder was changed to Ho2O3.

[0203] (Example 20) Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 1, except that Gd2O2S powder was used instead of Gd2O3 powder and sulfurization was not performed.

[0204] Example 21 Gd2O3 powder was added to the sodium alginate solution and mixed for 24 hours to create a slurry. The weight ratio of the raw powder to the alginate solution was 0.5 times. The created slurry was dropped into the calcium lactate solution, which was the gelling solution. A syringe was used to drop the slurry.

[0205] The diameter of the syringe was 510 μm, and the distance from the tip of the syringe to the liquid surface of the calcium lactate aqueous solution was 100 mm. The slurry dropped by the syringe was kept in the gelling solution for 5 hours.

[0206] The gelled granulated particles for use as cold storage material particles were then washed with pure water. After washing, the granulated particles for use as cold storage material particles were dried. The sodium concentration of the granulated particles for use as cold storage material particles was 0.83 atomic %, and the carbon concentration was 0.5 weight %. The relative density of the granulated particles for use as cold storage material particles was 27%. After drying, the granulated particles for use as cold storage material particles were degreased, sulfurized, and sintered.

[0207] The granulated particles for use as cold storage material particles were degreased at 500°C for 2 hours in an air atmosphere. After degreasing, the sodium concentration of the granulated particles for use as cold storage material particles was 1.0 atomic %, the carbon concentration was 0.25 weight %, and the relative density was 30%. After degreasing, the granulated particles for use as cold storage material particles were sulfurized by heat treatment at 600°C for 2 hours in an atmosphere containing hydrogen sulfide (H2S). The granulated particles for use as cold storage material particles were sintered by heat treatment at 1300°C for 12 hours in an inert gas atmosphere to produce cold storage material particles.

[0208] The main component of the regenerator particles of Example 21 was gadolinium oxysulfide. The sodium concentration in the regenerator particles of Example 21 was 1.1 atomic %.

[0209] (Examples 22 to 24) Granulated particles for ice storage material particles and ice storage material particles were produced in the same manner as in Example 21, except that the relative density of the granulated particles for ice storage material particles was changed by changing the ratio of raw material powder and sodium alginate aqueous solution, and sodium and calcium were removed by changing the washing time and number of times.

[0210] (Examples 25 to 26) Granulated particles for ice storage material particles and ice storage material particles were produced in the same manner as in Example 21, except that the concentration of the sodium alginate aqueous solution was changed to change the concentration of carbon contained in the granulated particles for ice storage material particles, and the washing time was adjusted.

[0211] Example 27 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 21, except that the aqueous magnesium chloride solution was used instead of the aqueous calcium lactate solution.

[0212] (Example 28) Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 21, except that the aqueous solution of strontium chloride was used instead of the aqueous solution of calcium lactate.

[0213] (Example 29) Except for using an air pulse dispenser instead of a syringe as a method for dropping the slurry, granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 21. The nozzle diameter was 510 μm, and the distance from the nozzle tip to the liquid surface of the calcium lactate aqueous solution was 100 mm.

[0214] (Example 30) Except for using a piezoelectric dispenser instead of a syringe as a method for dropping the slurry, granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 21. The nozzle aperture was 510 μm, and the distance from the nozzle tip to the liquid surface of the calcium lactate aqueous solution was 100 mm.

[0215] (Example 31) Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 21, except that a continuous ink jet was used as a method for dropping the slurry instead of a syringe.

[0216] (Examples 32 to 37) The granulated particles for cold storage material particles and the cold storage material particles of Examples 32 to 37 have different particle sizes or aspect ratios from the granulated particles for cold storage material particles and the cold storage material particles of Example 21. When producing the granulated particles for cold storage material particles of Examples 32 to 37, the aperture of the syringe and the distance from the tip of the syringe to the surface of the gelling solution were changed compared to when producing the granulated particles for cold storage material particles of Example 21.

[0217] (Example 38) Granulated particles for ice storage material particles and ice storage material particles were produced in the same manner as in Example 21, except that the relative density was set to 11% by changing the ratio of raw material powder and sodium alginate aqueous solution, and only calcium was removed by changing the soaking time, washing time and number of times.

[0218] (Example 39) Granulated particles for ice storage material particles and ice storage material particles were produced in the same manner as in Example 21, except that the relative density was set to 11% by changing the ratio of raw material powder and sodium alginate aqueous solution, and only sodium was removed by changing the soaking time, washing time and number of times.

[0219] (Example 40) Except for using Al2O3 powder as the raw powder, granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 22. The Al2O3 powder was added so that the Al content in the cold storage material particles was 15 atomic %.

[0220] (Example 41) Except for using Al2O3 powder as the raw powder, granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 38. The Al2O3 powder was added so that the Al content in the cold storage material particles was 15 atomic %.

[0221] (Example 42) Granulated particles for cold storage material particles and cold storage material particles were manufactured in the same manner as in Example 21, except that the relative density was set to 11% by changing the ratio of the raw material powder and the sodium alginate aqueous solution, and Al2O3 powder was also used as the raw material powder. The Al2O3 powder was added so that the Al contained in the cold storage material particles was 15 atomic %.

[0222] (Example 43) Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 21, except that the ratio of the raw material powder and the sodium alginate aqueous solution was changed to make the relative density 11%, and an aluminum chloride aqueous solution was used instead of the calcium lactate aqueous solution. Al was added so that the amount of Al contained in the cold storage material particles was 0.01 atomic %.

[0223] (Example 44) Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 21, except that the ratio of the raw material powder and the sodium alginate aqueous solution was changed to make the relative density 11%, and an aluminum chloride aqueous solution was used in addition to the calcium lactate aqueous solution. Al was added so that the amount of Al contained in the cold storage material particles was 0.01 atomic %.

[0224] (Example 45) Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 21, except that the ratio of the raw material powder and the sodium alginate aqueous solution was changed to make the relative density 11%, and an aluminum chloride aqueous solution was used in addition to the calcium lactate aqueous solution. Al was added so that the amount of Al contained in the cold storage material particles was 20 atomic %. (Example 46) Except for using Gd2O3 powder and Al2O3 powder as raw material powder and not performing heat treatment in an atmosphere containing hydrogen sulfide (H2S), granulated particles for cold storage material particles and cold storage material particles were manufactured in the same manner as in Example 1. The main component of the cold storage material particles is GdAlO3.

[0225] (Example 47) Granulated particles for the cold storage material particles and cold storage material particles were manufactured in the same manner as in Example 2, except that Gd2O3 powder and Al2O3 powder were used as the raw material powders and heat treatment was not performed in an atmosphere containing hydrogen sulfide (H2S). The main component was GdAlO3.

[0226] (Example 48) Granulated particles for the cold storage material particles and cold storage material particles were manufactured in the same manner as in Example 21, except that Gd2O3 powder and Al2O3 powder were used as the raw material powders and heat treatment was not performed in an atmosphere containing hydrogen sulfide (H2S). The main component was GdAlO3.

[0227] Comparative Example 1 The granulated particles for cold storage material particles of Comparative Example 1 differ from the granulated particles for cold storage material particles of Example 21 in that the relative density is as low as 9%. When producing the granulated particles for cold storage material particles of Comparative Example 1 and the cold storage material particles, the amount of raw material powder was reduced compared to when producing the granulated particles for cold storage material particles of Example 21.

[0228] Comparative Example 2 The granulated particles for cold storage material particles of Comparative Example 2 differ from the granulated particles for cold storage material particles of Example 21 in that the relative density is high at 51%. When producing the granulated particles for cold storage material particles of Comparative Example 2, the weight of the raw material powder was increased compared to when producing the granulated particles for cold storage material particles of Example 21.

[0229] Comparative Example 3 The granulated particles for use as cold storage material particles in Comparative Example 3 differ from the granulated particles for use as cold storage material particles in Example 21 in that the carbon concentration is as low as 0.0004% by weight. When producing the granulated particles for use as cold storage material particles in Comparative Example 3, the concentration of the sodium alginate aqueous solution was reduced compared to when producing the granulated particles for use as cold storage material particles in Example 21.

[0230] Comparative Example 4 The granulated particles for use as cold storage material particles in Comparative Example 4 differ from the granulated particles for use as cold storage material particles in Example 21 in that the carbon concentration is as high as 51% by weight. When producing the granulated particles for use as cold storage material particles in Comparative Example 4, the concentration of the sodium alginate aqueous solution was increased compared to when producing the granulated particles for use as cold storage material particles in Example 21.

[0231] Comparative Example 5 The granulated particles for cold storage material particles and the cold storage material particles of Comparative Example 5 are different from those of Example 41 in that the Al content in the cold storage material particles is as high as 65 atomic %. When producing the granulated particles for cold storage material particles and the cold storage material particles of Comparative Example 5, the weight of the Al2O3 powder was increased compared to when the granulated particles for cold storage material particles and the cold storage material particles of Example 41 were produced.

[0232] The strength of the granulated particles for cold storage material particles and the relative density and specific heat of the cold storage material particles were measured for the granulated particles for cold storage material particles and the cold storage material particles according to each of the Examples and Comparative Examples. The results are shown in Tables 1, 2, and 3. In Table 1, the granulated particles for cold storage material particles are referred to as "granulated particles," and the cold storage material particles produced from the granulated particles for cold storage material particles are referred to as "cold storage material particles."

[0233] [Table 1]

[0234] [Table 2]

[0235] [Table 3]

[0236] When the relative density of the granulated particles for use as cold storage material particles is less than 10%, the granulated particles cannot be collected as spherical particles, as in Comparative Example 1. This is believed to be because the strength of the granulated particles for use as cold storage material particles is significantly reduced due to the large proportion of voids contained in the granulated particles for use as cold storage material particles when the relative density is less than 10%.

[0237] When the relative density of the granulated particles for cold storage material particles exceeded 50% as in Comparative Example 2, the relative density of the cold storage material particles produced decreased significantly, and the specific heat also decreased significantly. This is believed to be because when the relative density of the granulated particles for cold storage material particles exceeded 50%, the organic components contained in the granulated particles for cold storage material particles could not be sufficiently removed, impairing the sinterability of the cold storage material particles.

[0238] From the results of Comparative Example 3, when the carbon concentration of the granulated particles for use as cold storage material particles is less than 0.001% by weight, the strength of the granulated particles for use as cold storage material particles is reduced, and therefore the granulated particles for use as cold storage material particles are easily broken during handling, resulting in a significant reduction in yield.

[0239] From the results of Comparative Example 4, when the carbon concentration of the granulated particles for the cold storage material particles exceeds 50% by weight, the relative density of the cold storage material particles after sintering is significantly decreased, and the specific heat is also significantly decreased. This is thought to be because the organic components contained in the granulated particles could not be sufficiently removed, and a large amount of carbon remained, which impaired the sinterability of the cold storage material particles.

[0240] From Examples 22 to 24, it can be seen that when no Group 1 element or Group 2 element is included, the relative density of the cold storage material particles is improved and the specific heat is also improved when the relative density is 15% to 50% compared to when the relative density is 10% to 15%. This is thought to be because when the relative density is too low, the number of contact points between the raw material powders decreases, and the sinterability of the cold storage material particles decreases.

[0241] From Example 38 and Example 39, it can be seen that when the first group element or the second group element is included, the relative density of the heat regenerator particles is improved and the specific heat is also improved even if the relative density is 10% or more and 15% or less. This is considered to be due to the sintering promotion effect of the first group element and the second group element.

[0242] As shown in Examples 40 to 45, even if the relative density is 10% or more and 15% or less, the relative density of the sintered particles is improved when a sintering aid is included. This is considered to be due to the sintering promotion effect of the sintering aid. When the relative density is less than 10%, the relative density of the cold storage material particles is low even if a sintering aid is included, and the specific heat is also small.

[0243] From the results of Comparative Example 5, it is understood that when the atomic concentration of the added element derived from the sintering aid is large, exceeding 60 atomic %, the specific heat of the regenerator particles decreases.

[0244] As shown in Examples 46 to 48, by not performing heat treatment in a hydrogen sulfide atmosphere, even if the main component of the heat storage material particles is GdAlO3, as long as the relative density of the granulated particles for the heat storage material particles is 10% or more and 50% or less, it is found that the same effect is obtained as when the main component is gadolinium oxysulfide.

[0245] From the above examples, the effects achieved by the granulated particles for cold storage material particles of the first embodiment and the cold storage material particles of the second embodiment were confirmed.

[0246] Although the above description has been given taking as an example an air pulse type dispenser or a piezoelectric type dispenser as the dispenser, a plunger type dispenser may also be used.

[0247] Although the above description has been given taking a continuous type inkjet as an example of the inkjet, an on-demand type inkjet may also be used.

[0248] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. For example, components of one embodiment may be replaced or changed with components of another embodiment. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0249] 100 Regenerative cryogenic refrigerator (refrigerator) 101 Granulated particles for cold storage material particles 115 Second regenerator (regenerator) 119 Second cold storage material (cold storage material particles) 500 Cryopump 600 Superconducting Magnet 700 Nuclear Magnetic Resonance Imaging Device 800 Nuclear Magnetic Resonance Spectrometer 900 Magnetic Field Application Type Single Crystal Pulling Apparatus 1000 Helium Recondenser

Claims

1. A raw material powder containing a rare earth oxysulfide containing at least one rare earth element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, or a raw material powder containing a rare earth oxide containing the at least one rare earth element, is mixed with a binder containing 0.01 wt % to 40 wt % of an organic substance to obtain a raw material mixture; A method for producing granulated particles for use in cold storage material particles, comprising granulating the raw material mixture by a rolling granulation method, an agitation granulation method, an extrusion method, a spraying method, or a press molding method, The carbon concentration of the granulated particles for the cold storage material particles is 0.001% by weight or more and 50% by weight or less, The method for producing granulated particles for use as cold storage material particles, wherein the granulated particles for use as cold storage material particles have a relative density of 10% or more and 50% or less.

2. A raw material powder containing a rare earth oxysulfide containing at least one rare earth element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, or a raw material powder containing a rare earth oxide containing the at least one rare earth element, is mixed with a dispersion medium containing an organic substance to prepare a slurry; A method for producing granulated particles for use in cold storage material particles, comprising dropping the slurry into a gelling solution to cause gelation and granulation, The weight ratio of the raw material powder to the dispersion medium is 0.1 times or more and 20 times or less, The carbon concentration of the granulated particles for the cold storage material particles is 0.001% by weight or more and 50% by weight or less, The method for producing granulated particles for use as cold storage material particles, wherein the granulated particles for use as cold storage material particles have a relative density of 10% or more and 50% or less.

3. 3. The method for producing granulated particles for use as cold storage material particles according to claim 1, wherein the particle size is from 50 μm to 7 mm.

4. 3. The method for producing granulated particles for use as cold storage material particles according to claim 1, wherein the aspect ratio is 1 or more and 5 or less.

5. 3. The method for producing granulated particles for use as cold storage material particles according to claim 1, further comprising a Group 1 element having a concentration of 0.001 atomic % or more and 60 atomic % or less.

6. 6. The method for producing granulated particles for use as regenerator particles according to claim 5, wherein the Group 1 element is at least one element selected from the group consisting of Li, Na, and K.

7. 3. The method for producing granulated particles for use as cold storage material particles according to claim 1, further comprising a Group II element having a concentration of 0.001 atomic % or more and 60 atomic % or less.

8. 8. The method for producing granulated particles for use as regenerator particles according to claim 7, wherein the Group II element is at least one element selected from the group consisting of Mg, Ca, Sr, and Ba.

9. 3. The method for producing granulated particles for use in cold storage material particles according to claim 1 or 2, further comprising an additive element having a concentration of 0.001 atomic % or more and 60 atomic % or less, the additive element being at least one element selected from the group consisting of Mn, Al, Fe, Cu, Ni, Co, Zr, Y, and B.

10. The method for producing granulated particles for use as cold storage material particles according to claim 2, which is a gel.

11. A method for producing cold storage material particles, comprising sintering the granulated particles for cold storage material particles according to claim 1 or 2.

12. The maximum volumetric specific heat in the temperature range from 2K to 10K is 0.5 J / (cm ３ The method for producing heat accumulating material particles according to claim 11, wherein the heat accumulating material particles have a molecular weight of 1000 or more.

13. The method for producing heat accumulating material particles according to claim 11, wherein the particle size is 50 μm or more and 5 mm or less.

14. The method for producing heat accumulating material particles according to claim 11, wherein the aspect ratio is 1 or more and 5 or less.

15. A method for producing a regenerator filled with a plurality of regenerator particles according to claim 11.

16. A method for manufacturing a refrigerator comprising the regenerator according to claim 15.

17. A method for manufacturing a cryopump comprising the refrigerator according to claim 16.

18. A method for producing a superconducting magnet, comprising the refrigerator according to claim 16.

19. A method for manufacturing a nuclear magnetic resonance imaging apparatus comprising the refrigerator according to claim 16.

20. A method for manufacturing a nuclear magnetic resonance apparatus comprising the refrigerator according to claim 16.

21. A method for producing a magnetic field application type single crystal pulling apparatus, comprising the refrigerator according to claim 16.

22. A method for producing a helium recondensing device comprising the refrigerator according to claim 16.

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