WO2016143664A1 - Mnbi-based magnetic powder, method for producing same, compound for bonded magnets, bonded magnet and metal magnet - Google Patents

Mnbi-based magnetic powder, method for producing same, compound for bonded magnets, bonded magnet and metal magnet Download PDF

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WO2016143664A1
WO2016143664A1 PCT/JP2016/056609 JP2016056609W WO2016143664A1 WO 2016143664 A1 WO2016143664 A1 WO 2016143664A1 JP 2016056609 W JP2016056609 W JP 2016056609W WO 2016143664 A1 WO2016143664 A1 WO 2016143664A1
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mnbi
powder
hexagonal
magnet
magnetic powder
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PCT/JP2016/056609
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French (fr)
Japanese (ja)
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信宏 片山
森本　耕一郎
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戸田工業株式会社
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Priority to CN201680013880.3A priority Critical patent/CN107408438A/en
Priority to JP2017505280A priority patent/JPWO2016143664A1/en
Publication of WO2016143664A1 publication Critical patent/WO2016143664A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C12/00—Alloys based on antimony or bismuth
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/06—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/06—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder
    • H01F1/08—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/02—Permanent magnets [PM]

Definitions

  • the present invention relates to a MnBi-based magnetic powder, a manufacturing method thereof, a bonded magnet compound, a bonded magnet, and a metal magnet.
  • MnBi magnet powder Since MnBi magnet powder has relatively high saturation magnetization and large crystal magnetic anisotropy, it is expected to be industrially used as a magnet for various motors. However, the oxidation resistance is low, and there is a drawback in that saturation magnetization decreases due to rapid oxidative corrosion particularly in an atmosphere containing water. Therefore, in order to eliminate such drawbacks, methods of coating with a binding resin or using a rust inhibitor have been attempted.
  • Patent Document 1 proposes a method of adding another metal element.
  • Patent Document 2 proposes to improve the corrosion resistance by adding an alkaline earth metal such as Sr to MnBi magnetic powder.
  • Patent Document 3 proposes to adsorb a cationic activator or amphoteric activator containing nitrogen atoms such as amine, amide, imide, etc. to MnBi magnetic powder to prevent oxidative degradation and to suppress a decrease in saturation magnetization. ing.
  • JP-A-9-139304 JP 2001-257110 A Japanese Patent Laid-Open No. 9-7163
  • the present invention provides a MnBi-based magnetic powder that can maintain high saturation magnetization even when stored in a high-temperature, high-humidity environment for a long period of time, and a method for producing such a MnBi-based magnetic powder. For the purpose.
  • the present invention provides a bonded magnet that can maintain high saturation magnetization even when stored in a high-temperature and high-humidity environment for a long period of time, and a bonded magnet that can manufacture such a bonded magnet.
  • the purpose is to provide a compound.
  • Another object of the present invention is to provide a metal magnet that can maintain high saturation magnetization even when stored in a high temperature and high humidity environment for a long period of time.
  • the present invention includes a hexagonal MnBi magnetic phase, and the content of Zn in the hexagonal MnBi magnetic phase is 0.5 to 8% by mass.
  • An MnBi magnetic powder is provided.
  • the above MnBi magnetic powder contains 0.5 to 8% by mass of Zn in the hexagonal MnBi magnetic phase having low oxidation resistance. This is presumed to improve the oxidation resistance of the hexagonal MnBi magnetic phase in a high temperature and high humidity environment. As a result, the MnBi magnetic powder can maintain high saturation magnetization even when stored for a long time in a high temperature and high humidity environment.
  • the present invention provides a hexagonal MnBi magnetic material containing Zn by mixing MnBi alloy powder and Zn powder and heat-treating them at 280 to 380 ° C. in an inert gas atmosphere under vacuum or reduced pressure.
  • a method for producing an MnBi-based magnetic powder comprising a step of obtaining a MnBi-based magnetic powder containing a phase, wherein the content of Zn in the hexagonal MnBi magnetic phase is 0.5 to 8% by mass.
  • MnBi-based magnetic powder manufacturing method a mixture of MnBi alloy powder and Zn powder is heated to 280 to 380 ° C. in a vacuum or in an inert gas atmosphere under reduced pressure. Thereby, Zn is vaporized, Zn is diffused into the hexagonal MnBi magnetic phase, and a hexagonal MnBi magnetic phase having a Zn content of 0.5 to 8% by mass is obtained.
  • the hexagonal MnBi magnetic phase thus obtained is presumed to have improved oxidation resistance in a high temperature and high humidity environment.
  • the MnBi-based magnetic powder obtained by the above production method can maintain high saturation magnetization even when stored for a long time in a high temperature and high humidity environment.
  • the present invention provides a process for obtaining a MnBi-based magnetic powder containing a hexagonal MnBi magnetic phase containing Zn by performing heat treatment and pulverization of a quenched ribbon obtained by melting and quenching an MnBiZn alloy. And a method for producing MnBi-based magnetic powder, wherein the content of Zn in the hexagonal MnBi magnetic phase is 0.5 to 8% by mass.
  • MnBi magnetic powder having a Zn content of 0.5 to 8% by mass in the hexagonal MnBi magnetic phase is obtained by melting and quenching, followed by heat treatment and pulverization. Yes.
  • Such MnBi-based magnetic powder can maintain high saturation magnetization even when stored for a long time in a high temperature and high humidity environment.
  • Either heat treatment or pulverization may be performed first.
  • the heat treatment is preferably performed at 280 to 380 ° C. in an inert gas atmosphere.
  • the present invention provides a bonded magnet compound comprising a kneaded material containing the above-described MnBi-based magnetic powder and a resin binder, and a bonded magnet including the above-described MnBi-based magnetic powder and a resin binder. . Since such a compound and bond magnet contain the MnBi magnetic powder having the above-described characteristics, high saturation magnetization can be maintained even if stored for a long time in a high temperature and high humidity environment.
  • the present invention includes a hexagonal MnBi magnetic phase containing Zn, and the content of Zn in the hexagonal MnBi magnetic phase is 0.5 to 8 mass relative to the total of Mn, Bi and Zn. %, Provide a metal magnet.
  • This metal magnet can be obtained by heat-treating or sintering a molded body produced by pressure-molding the above-described MnBi-based magnetic powder.
  • Such a metal magnet contains 0.5 to 8% by mass of Zn in a hexagonal MnBi magnetic phase having low oxidation resistance. This is presumed to improve the oxidation resistance of the hexagonal MnBi magnetic phase in a high temperature and high humidity environment. As a result, the metal magnet can maintain high saturation magnetization even if stored for a long time in a high temperature and high humidity environment.
  • the present invention it is possible to provide a MnBi-based magnetic powder capable of maintaining high saturation magnetization even when stored in a high-temperature and high-humidity environment for a long period of time, and a method for producing such MnBi-based magnetic powder.
  • the present invention also provides a bonded magnet that can maintain a high saturation magnetization even when stored in a high temperature and high humidity environment for a long period of time, and a bonded magnet compound capable of producing such a bonded magnet. Can do.
  • the present invention can provide a metal magnet that can maintain high saturation magnetization even when stored in a high temperature and high humidity environment for a long period of time.
  • FIG. 1A is an example of an electron micrograph showing an enlarged part of the cross section of the MnBi-based magnetic powder.
  • FIG. 1B is a diagram schematically showing a cross-sectional structure shown in the electron micrograph of FIG.
  • FIG. 2A is another example of an electron micrograph showing an enlarged part of a cross section of the MnBi-based magnetic powder.
  • FIG. 2B is a diagram showing a result of performing line analysis (EDX analysis) in the electron micrograph of FIG.
  • FIG. 3 is a flowchart showing a specific example of a method for producing an MnBi-based magnetic powder, a bonded magnet, and a metal magnet.
  • FIG. 1A is an example of an electron micrograph showing an enlarged part of the cross section of the MnBi-based magnetic powder.
  • FIG. 1B is a diagram schematically showing a cross-sectional structure shown in the electron micrograph of FIG.
  • FIG. 2A is another example of an electron micrograph showing an enlarged part of
  • FIG. 4 is a flowchart showing another specific example of a method for producing an MnBi-based magnetic powder, a bonded magnet, and a metal magnet.
  • FIG. 5 is a flowchart showing still another specific example of a method for producing an MnBi-based magnetic powder, a bond magnet, and a metal magnet.
  • FIG. 6 is a perspective view showing an embodiment of the MnBi-based metal magnet.
  • the MnBi magnetic powder of the present embodiment contains a hexagonal MnBi magnetic phase as a main component.
  • a hexagonal MnBi magnetic phase in addition to the hexagonal MnBi magnetic phase, at least one of a Bi phase and a Mn phase may be contained as a subcomponent.
  • the Mn phase is formed from Mn and Mn oxide.
  • the Bi phase is formed from Bi.
  • the total content of Mn and Bi in the MnBi magnetic powder may be, for example, 90% by mass or more, or 94% by mass or more.
  • the content ratio of Mn to the total of Mn and Bi is preferably 35 to 65 mol%, more preferably 37.5 to 50 mol%.
  • Mn the ratio of the hexagonal MnBi magnetic phase decreases, and the magnetization value tends to decrease.
  • the content ratio of Mn becomes too high, Bi is insufficient, the ratio of the hexagonal MnBi magnetic phase decreases, and the magnetization value tends to decrease.
  • the proportion of the Bi phase decreases, and the anisotropy in the heat treatment in the magnetic field tends to be insufficient.
  • excess Mn it will become easy to form MnZn and it exists in the tendency for Zn content in a MnBi magnetic phase to reduce.
  • the Zn content in the MnBi-based magnetic powder may be, for example, 0.3 to 5% by mass, or 0.4 to 4% by mass. Good.
  • the average particle diameter of the MnBi magnetic powder is, for example, 3 to 150 ⁇ m.
  • FIG. 1 (A) is an example of an electron micrograph showing an enlarged part of a cross section obtained by embedding a MnBi-based magnetic powder of the present embodiment in a resin and polishing it with a cross section polisher.
  • FIG. 1B is a diagram schematically showing a cross-sectional structure shown in the electron micrograph of FIG.
  • the MnBi-based magnetic powder contains a hexagonal MnBi magnetic phase 10 and a Bi phase 20 adjacent thereto. 1A and 1B also show the resin 30 used for embedding the MnBi magnetic powder.
  • the hexagonal MnBi magnetic phase 10 contains Zn in addition to Mn and Bi.
  • the content of Zn in the hexagonal MnBi magnetic phase 10 is 0.5 to 8% by mass, preferably 0.9 to 6% by mass.
  • excellent corrosion resistance tends to be impaired.
  • the Zn content is excessive, the nonmagnetic component increases and the magnetization value tends to decrease.
  • FIG. 2 (A) is another example of an electron micrograph showing an enlarged part of a cross section obtained by embedding the MnBi-based magnetic powder of the present embodiment in a resin and polishing it with a cross section polisher.
  • FIG. 2B is a diagram illustrating a result of performing line analysis (EDX analysis) along the line segment with the point a as a starting point in the electron micrograph of FIG.
  • EDX analysis line analysis
  • the MnBi-based magnetic powder contains a hexagonal MnBi magnetic phase 10 and Bi phases 20 and 20 so as to sandwich this.
  • the hexagonal MnBi magnetic phase 10 contains Mn, Bi, and Zn.
  • the Bi phase 20 is substantially free of Mn and Zn.
  • the hexagonal MnBi magnetism is maintained while keeping the ratio of nonmagnetic components low by allowing Zn to be unevenly distributed in the hexagonal MnBi magnetic phase 10 of the MnBi-based magnetic powder.
  • the corrosion resistance of the phase 10 can be effectively improved.
  • the Zn content in the Bi phase 20 is, for example, 0.01% by mass or less.
  • the Zn content in the Mn phase is, for example, 10% by mass or less.
  • the ratio of the hexagonal MnBi magnetic phase 10 in the MnBi-based magnetic powder may be, for example, 60 to 98% as an area ratio in a cross-sectional electron micrograph as shown in FIGS. 1 (A) and 2 (A). 70-95%. If the area ratio is too low, the ratio of the nonmagnetic phase tends to increase and the saturation magnetization value tends to decrease. On the other hand, if this area ratio becomes too high, for example, when the particles are larger than the size of the single magnetic domain, the Bi phase 20 that dissolves when the magnetic powder is obtained by performing the heat treatment in the magnetic field decreases. This tends to make it difficult for the hexagonal MnBi magnetic phase 10 to be oriented during heat treatment in a magnetic field. However, when the particles are substantially the same as the single magnetic domain size, the ratio of the hexagonal MnBi magnetic phase 10 may be high because it is not necessary to orient the hexagonal MnBi magnetic phase 10 within the particle.
  • the MnBi magnetic powder of this embodiment may be a magnet powder that has been heat-treated in a magnetic field.
  • the hexagonal MnBi magnetic phase has high oxidation resistance.
  • the MnBi-based magnetic powder can reduce the decrease in saturation magnetization even when stored for a long time in a high temperature and high humidity environment. Bond magnets and metal magnets formed using such MnBi-based magnetic powder can reduce the decrease in saturation magnetization even when stored for a long time in a high temperature and high humidity environment.
  • a method for producing an MnBi-based magnetic powder includes a step of obtaining an MnBi alloy powder, and heating a mixed powder containing the MnBi alloy powder and the Zn powder to 280 to 380 ° C. under reduced pressure to obtain a hexagonal MnBi Forming a magnetic phase and diffusing Zn inside the hexagonal MnBi magnetic phase to obtain a MnBi-based magnetic powder having a Zn content of 0.5 to 8 mass% in the hexagonal MnBi magnetic phase.
  • magnetic powder containing MnBi as a main component and Zn or the like as a subcomponent is referred to as MnBi-based magnetic powder in this specification.
  • MnBi alloy powder is obtained by (i) powder metallurgy method for obtaining MnBi alloy powder by crushing and sintering Mn and Bi, and (ii) obtaining MnBi alloy powder by melting and atomizing MnBi alloy.
  • Atomizing method (iii) Melting method to obtain MnBi alloy powder by pulverizing MnBi alloy lump obtained by melting in an arc furnace, (iv) Quenching the molten MnBi alloy with a roll, It can be manufactured using a liquid quenching method in which MnBi alloy powder is obtained by pulverization.
  • a chip, a shot, a powder, or the like can be appropriately selected and used as the Mn raw material and the Bi raw material.
  • a Zn raw material a chip, a shot, a powder, or the like can be appropriately selected and used.
  • the liquid quenching method (iv) is preferable.
  • an MnBi alloy powder having a sufficiently small particle size can be obtained by pulverizing a quenched ribbon obtained by quenching a molten alloy with a roll.
  • Zn can be sufficiently diffused into the hexagonal MnBi magnetic phase in the heat treatment step.
  • FIG. 3 is a flowchart showing a specific example of a method for producing MnBi-based magnetic powder, a compound for bonded magnet, a bonded magnet, and a metal magnet.
  • the MnBi alloy powder is prepared using the above (iv) liquid quenching method. That is, first, a Mn raw material and a Bi raw material are prepared, and a melting step S1 for melting (melting casting) the MnBi alloy by, for example, arc melting or the like is performed. Thereafter, a liquid quenching step S2 for obtaining a quenched ribbon by a liquid quenching method is performed. Subsequently, a coarse pulverization step S3 for coarsely pulverizing the obtained quenched ribbon is performed to obtain an MnBi alloy powder.
  • the MnBi alloy powder and the Zn powder obtained as described above are mixed.
  • the mixing ratio at this time is such that 1 to 10% by mass of Zn powder is mixed with MnBi alloy powder.
  • Zn powder since Zn powder is vaporized, it is preferable to mix more Zn powder than the Zn content of the target MnBi magnetic powder.
  • the mixed powder of the MnBi alloy powder and the Zn powder is 280 to 380 ° C. (preferably 300 to 370 ° C.) in vacuum or in an inert gas atmosphere under reduced pressure (preferably 10 Pa or less). Heat for 30-200 minutes.
  • the inert gas include argon gas and nitrogen gas.
  • the heating temperature under the above heating conditions is less than 280 ° C.
  • Zn is not sufficiently vaporized, so that the heat treatment step S5 tends to be long.
  • the hexagonal MnBi magnetic phase tends not to be generated sufficiently.
  • the heating temperature exceeds 380 ° C.
  • the structural phase transition of the hexagonal MnBi magnetic phase from the ferromagnetic low temperature phase to the paramagnetic high temperature phase occurs, and the ferromagnetism tends to disappear.
  • Bi dissolves and the Bi phase precipitates the ratio of the hexagonal MnBi magnetic phase tends to decrease and the saturation magnetization value tends to decrease.
  • the treatment time under the above heating conditions is too short, Zn diffusion does not proceed sufficiently, and a sufficient corrosion resistance improvement effect may not be obtained. Further, the hexagonal MnBi magnetic phase tends not to be generated sufficiently. On the other hand, if the treatment time is too long, the hexagonal MnBi magnetic phase grows and the coercive force tends to decrease.
  • the hexagonal MnBi magnetic phase in the MnBi-based magnetic powder obtained by the above-described manufacturing method has high oxidation resistance. For this reason, the MnBi-based magnetic powder can reduce the decrease in saturation magnetization even when stored for a long time in a high temperature and high humidity environment.
  • a magnetic field heat treatment step S6 is performed.
  • the magnetic field heat treatment step S6 is performed by heating the MnBi magnetic powder at a temperature of 260 to 380 ° C. for 30 to 600 minutes while applying a magnetic field of 0.4 to 0.8 T (4000 to 8000 G), for example. it can. By performing such a heat treatment step S6 in a magnetic field, anisotropic magnet powder can be obtained.
  • the heating temperature in the heat treatment step S6 in a magnetic field is too low, there is a tendency that it is difficult to be anisotropic enough. On the other hand, if the heating temperature is too high, a structural phase transition of the hexagonal MnBi magnetic phase from the ferromagnetic low temperature phase to the paramagnetic high temperature phase occurs, and the ferromagnetism tends to disappear. If the heating time in the heat treatment step S6 in the magnetic field is too short, there is a tendency that it is difficult to be anisotropic enough. On the other hand, it is sufficient that the heating time is about 600 minutes.
  • anisotropic magnet powder which has desired particle size by performing crushing process S7 after heat processing process S6 in a magnetic field.
  • the present invention is not limited to such a procedure.
  • the particles are reduced to a single domain size in the pulverization step S7 without performing the heat treatment step S6 in the magnetic field.
  • An anisotropic magnet powder may be obtained by pulverization.
  • an in-magnetic field forming step S8 is performed in which anisotropic magnet powder is formed in a magnetic field to produce a compact.
  • the applied magnetic field is, for example, 0.4 to 0.8 T (4000 to 8000 G), and the molding pressure is, for example, 1 to 10 t / cm 2 .
  • a heat treatment step S9 is performed in which the obtained molded body is heated at a temperature of 200 to 380 ° C. for 1 to 10 hours in an inert gas atmosphere.
  • a hot compression step of applying pressure while heating may be performed.
  • an anisotropic MnBi-based metal magnet can be manufactured.
  • the MnBi-based metal magnet obtained using the MnBi-based magnetic powder can maintain high saturation magnetization even when used in a high-temperature and high-humidity environment.
  • a molding step S20 is performed in which the MnBi-based magnetic powder is molded to produce a molded body.
  • the molding can be performed by a known method such as compression molding or injection molding at a molding pressure of 1 to 10 t / cm 2 .
  • the in-magnetic field sintering step S21 is performed using the obtained molded body. Thereby, an anisotropic MnBi-based metal magnet can be obtained. Sintering in a magnetic field can be performed by heating at a temperature of 280 to 380 ° C.
  • MnBi-based metal magnet obtained by this manufacturing method is also obtained using the MnBi-based magnetic powder, high saturation magnetization can be maintained even when used in a high temperature and high humidity environment.
  • a bonded magnet can be manufactured by performing a molding step S11 in which a compound for a bonded magnet obtained by kneading is molded in a magnetic field of, for example, 0.4 to 0.8 T (4000 to 8000 G).
  • the molding can be performed by a known method such as compression molding or injection molding at a molding pressure of 1 to 10 t / cm 2 .
  • the resin binder may be a thermosetting resin such as an epoxy resin.
  • the magnet powder and the resin binder are kneaded and molded by pressure molding or the like, and then a heat treatment is performed to manufacture a bonded magnet.
  • the bond magnet obtained by using the MnBi-based magnetic powder can suppress a decrease in saturation magnetization even when used in a high temperature and high humidity environment.
  • the manufacturing method of the MnBi-based magnetic powder of this embodiment is a method of melting and quenching a Mn raw material, a Bi raw material, and a Zn raw material, followed by a melt quenching method in which a rapidly cooled ribbon is obtained, and then subjecting the quenched ribbon to heat treatment and pulverization
  • a MnBi-based magnetic powder containing a hexagonal MnBi magnetic phase and having a Zn content of 0.5 to 8% by mass in the hexagonal MnBi magnetic phase is a method of melting and quenching a Mn raw material, a Bi raw material, and a Zn raw material.
  • FIG. 4 is a flowchart showing another specific example of a method for producing a MnBi magnetic powder and a method for producing a bonded magnet compound, a bonded magnet, and a metal magnet using the MnBi magnetic powder obtained by the production method.
  • a preparation step S31 for preparing a MnBi alloy by any one of the methods (i) to (iv) of the above embodiment is performed using a Mn raw material and a Bi raw material.
  • MnBiZn alloy an alloy containing MnBi as a main component and Zn or the like as a subcomponent.
  • the melting step S32 since a part of the evaporated Zn is scattered, it is preferable to add more Zn than the target Zn content of the MnBi-based magnetic powder. For example, 1 to 10% by mass of Zn is added to the MnBi alloy.
  • a liquid quenching step S33 for quenching the melted MnBiZn alloy by a melt quenching method and a coarse pulverizing step S34 are performed.
  • the quenched ribbon is roughly pulverized by a known method to obtain MnBi-based alloy powder.
  • This MnBi-based alloy powder is a nonmagnetic powder containing MnBi as a main component and Zn or the like as a subcomponent.
  • a heat treatment step S6 in a magnetic field and a pulverization step S7 can be performed to obtain an MnBi-based magnetic powder (magnet powder).
  • the heat treatment step S6 in the magnetic field and the pulverization step S7 can be performed in the same manner as the flowchart shown in FIG. In this case, the procedure is not limited to this.
  • the particles are made into a single domain size in the pulverization step S7 without performing the heat treatment step S6 in the magnetic field.
  • an anisotropic magnet powder is obtained after the hexagonal MnBi magnetic phase is sufficiently generated in the heat treatment step S5, the particles are made into a single domain size in the pulverization step S7 without performing the heat treatment step S6 in the magnetic field.
  • the MnBi-based metal magnet can be manufactured by performing the forming step S8 in the magnetic field and the heat treatment step S9 in the same manner as the flowchart shown in FIG.
  • the MnBi-based metal magnet may be manufactured by performing the molding step S20 and the magnetic field sintering step S21 using the MnBi-based magnetic powder.
  • the bonded magnet may be manufactured by performing the kneading step S10 and the forming step S11 using the MnBi-based magnetic powder and the resin binder.
  • the hexagonal MnBi magnetic phase in the MnBi magnetic powder obtained by this production method has high oxidation resistance. For this reason, the MnBi-based magnetic powder can reduce the decrease in saturation magnetization even when stored for a long time in a high temperature and high humidity environment.
  • FIG. 5 is a flowchart showing still another specific example of a method for producing a MnBi-based magnetic powder and a method for producing a compound for a bonded magnet, a bonded magnet, and a metal magnet using the MnBi-based magnetic powder obtained by this manufacturing method. is there.
  • the heat treatment step S34 is performed after the preparation step S31, the dissolution step S32, and the liquid quenching step S33, as in the flowchart shown in FIG.
  • the quenched ribbon after liquid quenching is heated at 280 to 380 ° C. (preferably 300 to 370 ° C.) for 30 to 200 minutes in an inert gas atmosphere.
  • the heat treatment step S34 may be performed, for example, in an inert gas atmosphere under a reduced pressure of 10 Pa or less, or in a vacuum.
  • an MnBi-based alloy having a hexagonal MnBi magnetic phase containing a predetermined amount of Zn is obtained.
  • the MnBi magnetic powder can be obtained.
  • each powder is pulverized using a ball mill or the like until it reaches a single magnetic domain level of about 10 ⁇ m (single crystal size). If pulverized to this extent, anisotropic MnBi magnet powder can be obtained without applying a magnetic field.
  • the MnBi metal magnet can be obtained by performing the forming step S8 in the magnetic field and the heat treatment step S9. Similar to the flowchart shown in FIG. 4, the MnBi-based metal magnet and the bonded magnet can be manufactured by performing the steps in the magnetic field forming step S8 or the kneading step S10 and the subsequent steps.
  • FIG. 6 is a perspective view of the MnBi-based metal magnet 50.
  • the shape of the MnBi-based metal magnet is not limited to the cylindrical shape as shown in FIG. 6, and may be, for example, a prismatic shape or a spherical shape.
  • the bonded magnet may also have a cylindrical shape as shown in FIG. 6, a prismatic shape, or a spherical shape.
  • the composition of the MnBi-based metal magnet 50 includes a hexagonal MnBi magnetic phase containing Zn.
  • the content of Zn in the hexagonal MnBi magnetic phase is 0.5 to 8% by mass with respect to the total of Mn, Bi and Zn. This content may be, for example, 0.3 to 5% by mass or 0.4 to 4% by mass from the viewpoint of improving corrosion resistance while maintaining high magnetic properties.
  • the contents of Mn, Bi and Zn in the hexagonal MnBi magnetic phase of the MnBi-based metal magnet 50 may be the same as those described in the embodiment of the MnBi-based magnetic powder.
  • the MnBi-based metal magnet 50 can be obtained by heat-treating or sintering a molded body produced by pressure-molding the above-described MnBi-based magnetic powder.
  • the compound for bond magnet is composed of a kneaded product of the above-described MnBi-based magnetic powder and a resin binder.
  • the bonded magnet is obtained by molding such a bonded magnet compound.
  • the bonded magnet includes the MnBi-based magnetic powder and the resin binder according to the above-described embodiment.
  • the composition of the bonded magnet compound and the MnBi-based magnetic powder contained in the bonded magnet may be the same as described in the above embodiment.
  • Example 1 ⁇ Production of magnet powder>
  • the Mn chip and Bi shot were melted in an arc melting furnace to prepare a MnBi alloy.
  • 5 g of the MnBi alloy obtained in the arc melting furnace was put into a hot water discharge nozzle of a transparent quartz tube having an orifice diameter of ⁇ 0.45 mm at the bottom. After evacuating the chamber of the liquid quenching apparatus, the MnBi alloy in the hot water nozzle was melted by high frequency melting in an argon gas atmosphere of 50 kPa.
  • a MnBi molten metal was sprayed onto a copper roll at a molten metal injection pressure of 10 kPa to obtain a quenched ribbon.
  • the rotational speed of the roll was 20 m / s, and the distance between the roll and the hot water nozzle was 0.4 mm.
  • the obtained quenched ribbon was pulverized to obtain a MnBi alloy powder having a particle size of 150 ⁇ m or less.
  • a mixed powder was prepared by mixing Zn powder (3.0% by mass) with MnBi alloy powder (100% by mass).
  • the mixed powder was heat-treated in an inert gas (nitrogen gas) atmosphere of 10 Pa or less at a temperature of 320 ° C. for 120 minutes to diffuse Zn into MnBi.
  • the temperature at this time is shown as “heat treatment temperature” in Table 1.
  • an MnBi magnetic powder was obtained.
  • MnBi magnetic powder is subjected to heat treatment in a magnetic field in which a magnetic field of 0.6 T (6000 G) is applied, and the magnet powder is obtained. Obtained.
  • Example 2 A magnetic powder was obtained by preparing a MnBi magnetic powder in the same manner as in Example 1 except that a mixed powder was prepared by mixing a Zn powder (5.0% by mass) with an MnBi alloy powder (100% by mass). It was. Evaluations 1 and 2 were performed in the same manner as in Example 1. The evaluation results are as shown in Tables 1 and 2.
  • Example 3 A magnetic powder was obtained by preparing a MnBi magnetic powder in the same manner as in Example 1 except that the temperature during heat treatment of the mixed powder was 360 ° C. Evaluations 1 and 2 were performed in the same manner as in Example 1. The evaluation results are as shown in Tables 1 and 2.
  • Example 4 A magnetic powder was obtained by preparing a MnBi magnetic powder in the same manner as in Example 3 except that a mixed powder was prepared by mixing a Zn powder (5.0 mass%) with an MnBi alloy powder (100 mass%). It was. The magnet powder was evaluated in the same manner as in Example 3. The evaluation results are as shown in Tables 1 and 2.
  • Example 6 The Mn chip and Bi shot were melted in an arc melting furnace to prepare a MnBi alloy.
  • 1% by mass of Zn was added to the MnBi alloy (100% by mass) obtained in the arc melting furnace, and again melted in the arc melting furnace.
  • 5 g of the obtained MnBiZn alloy was put into a hot water nozzle of a transparent quartz tube having an orifice diameter of ⁇ 0.45 mm at the bottom.
  • the MnBiZn alloy in the hot water nozzle was melted by high-frequency melting in an argon gas atmosphere of 50 kPa. Then, a MnBiZn molten metal was sprayed onto a copper roll at a molten metal injection pressure of 10 kPa to obtain a quenched ribbon.
  • the rotational speed of the roll was 20 m / s, and the distance between the roll and the hot water nozzle was 0.4 mm.
  • the obtained quenched ribbon was coarsely pulverized to obtain a MnBi alloy powder having a particle size of 150 ⁇ m or less.
  • MnBi-based alloy powder is subjected to heat treatment in a magnetic field in which a magnetic field of 0.6 T (6000 G) is applied, and MnBi-based magnetic powder ( Magnet powder) was obtained.
  • Table 1 shows the temperature of the heat treatment in the magnetic field at this time. Evaluations 1 and 2 were performed in the same manner as in Example 1. The evaluation results are as shown in Tables 1 and 2.
  • Example 7 A MnBi-based alloy powder was prepared in the same manner as in Example 6 except that 2% by mass of Zn was added to the MnBi alloy (100% by mass) obtained in the arc melting furnace to obtain a magnet powder. Evaluations 1 and 2 were performed in the same manner as in Example 1. The evaluation results are as shown in Tables 1 and 2.
  • Example 8 In the same manner as in Example 6, a MnBiZn molten metal was sprayed onto the roll to obtain a quenched ribbon.
  • the quenched ribbon was heat treated (atmosphere: argon gas, temperature: 300 ° C., time: 240 minutes). This heat treatment was performed in an inert gas atmosphere of 10 Pa or less. Table 1 shows the temperature of the heat treatment at this time.
  • the quenched ribbon was pulverized using a ball mill (conditions: 50 rpm, 2 hours) until the particle size became 63 ⁇ m or less to obtain MnBi-based magnetic powder (magnet powder). The average particle size of the magnet powder was 15 ⁇ m.
  • Evaluations 1 and 2 were performed in the same manner as in Example 1. The evaluation results are as shown in Tables 1 and 2.
  • Example 1 A magnetic powder was obtained by preparing a MnBi magnetic powder in the same manner as in Example 1 except that the Zn powder was not mixed. Evaluations 1 and 2 were performed in the same manner as in Example 1. The evaluation results are as shown in Tables 1 and 2.
  • Example 2 A magnetic powder was obtained by preparing a MnBi magnetic powder in the same manner as in Example 1 except that a mixed powder was prepared by mixing a Zn powder (8.0% by mass) with MnBi alloy powder (100% by mass). It was. Evaluations 1 and 2 were performed in the same manner as in Example 1. The evaluation results are as shown in Tables 1 and 2.
  • Table 2 shows the saturation magnetization deterioration rate calculated by the following equation from the values of saturation magnetization before and after storage for 4 days in air at a temperature of 40 ° C. and a relative humidity of 50%.
  • Saturation magnetization deterioration rate (%) 100 ⁇ [saturation magnetization after storage] / [saturation magnetization before storage] ⁇ 100
  • the Zn content (2) of the magnet powder of each example was in the range of 0.5 to 8% by mass.
  • the magnet powder of each example had a saturation magnetization deterioration rate of 5% or less even after being stored in air at a temperature of 40 ° C. and a relative humidity of 50% for 4 days.
  • oxygen content was 3000 ppm or less. From this, it was confirmed that the magnet powders of the respective examples contain a predetermined amount of Zn in the hexagonal MnBi magnetic phase, thereby suppressing oxidative deterioration and reducing the deterioration rate of saturation magnetization.
  • Comparative Example 1 since the hexagonal MnBi magnetic phase did not contain Zn, it was confirmed that the deterioration rate of saturation magnetization increased due to the progress of oxidation deterioration.
  • the oxygen content of the magnet powder of Comparative Example 1 was higher than that of the example.
  • the saturation magnetization deterioration rate of Examples 1, 6, 7, and 8 when stored under condition (1) is 15% or less, and the saturation magnetization deterioration rate is significantly higher than that of Comparative Example 1. It was getting smaller.
  • the deterioration rate of saturation magnetization of Examples 1, 6, 7, and 8 when stored under the condition (2) is 20% or less, and the deterioration rate of saturation magnetization is significantly higher than that of Comparative Example 1. It was getting smaller.
  • Example 9 Comparative Examples 3 to 12
  • Magnet powder was obtained in the same manner as in Example 6 except that the elements added to the MnBi alloy were as shown in Table 5.
  • a magnetic powder was prepared by heat-treating MnBi alloy powder containing no additive element under the same conditions as in Example 6 (Comparative Example 3).
  • the prepared magnet powder was stored at normal temperature (about 20 ° C.) in the air.
  • the saturation sample (4 ⁇ I max ), residual magnetic flux density (Br), and coercive force (Hcj) before storage and after storage (after 4 days and 15 days) were measured using a vibrating sample magnetometer (VSM: VSM manufactured by Toei Industry Co., Ltd.). -5 type). Table 5 shows the measurement results.
  • the magnet powder of Example 9 to which Zn was added had high saturation magnetization even after storage for 15 days. That is, it was confirmed that by using Zn, oxidation is sufficiently suppressed and high saturation magnetization can be maintained.
  • Comparative Examples 9 to 12 since the saturation magnetization at the initial stage (before storage) was too low, evaluation after storage was not performed.
  • the present invention it is possible to provide a MnBi-based magnetic powder capable of maintaining high saturation magnetization even when stored in a high-temperature and high-humidity environment for a long period of time, and a method for producing such MnBi-based magnetic powder.
  • the present invention also provides a bonded magnet that can maintain high saturation magnetization even when stored in a high temperature and high humidity environment for a long period of time, a compound for bonded magnet that can produce such a bonded magnet, and a metal magnet. Can be provided.

Abstract

Provided is an MnBi-based magnetic powder which contains a hexagonal MnBi magnetic phase, and wherein the content of Zn in the hexagonal MnBi magnetic phase is 0.5-8% by mass. Also provided is a bonded magnet which contains this Mn-Bi-based magnetic powder and a resin binder. Also provided is a metal magnet which contains a hexagonal MnBi magnetic phase containing Zn, and wherein the content of Zn relative to the total content of Mn, Bi and Zn in the hexagonal MnBi magnetic phase is 0.5-8% by mass.

Description

ＭｎＢｉ系磁性粉末及びその製造方法、並びに、ボンド磁石用コンパウンド、ボンド磁石、及び金属磁石MnBi-based magnetic powder, method for producing the same, bond magnet compound, bond magnet, and metal magnet
　本発明は、ＭｎＢｉ系磁性粉末及びその製造方法、並びに、ボンド磁石用コンパウンド、ボンド磁石、及び金属磁石に関する。 The present invention relates to a MnBi-based magnetic powder, a manufacturing method thereof, a bonded magnet compound, a bonded magnet, and a metal magnet.
　ＭｎＢｉ磁石粉末は、比較的高い飽和磁化と大きな結晶磁気異方性を有するため、各種モータ用磁石等として工業的に利用されることが期待されている。しかし、耐酸化性が低く、特に水を含む雰囲気中で急速に酸化腐食して飽和磁化が低下するという欠点がある。そこで、このような欠点を解消するために、結合樹脂で被覆したり、防錆剤を用いたりする方法が試みられている。 Since MnBi magnet powder has relatively high saturation magnetization and large crystal magnetic anisotropy, it is expected to be industrially used as a magnet for various motors. However, the oxidation resistance is low, and there is a drawback in that saturation magnetization decreases due to rapid oxidative corrosion particularly in an atmosphere containing water. Therefore, in order to eliminate such drawbacks, methods of coating with a binding resin or using a rust inhibitor have been attempted.
　別の方法としては、別の金属元素を添加する方法が試みられている。例えば、特許文献１では、六方晶ＭｎＢｉのＭｎの一部をＮｉで置換している。これによって、電気化学的に結晶構造を安定化し、腐食環境下における分解を防ぐことが提案されている。特許文献２ではＭｎＢｉ磁性粉末にＳｒ等のアルカリ土類金属を添加することによって耐食性を向上することが提案されている。 As another method, a method of adding another metal element has been tried. For example, in Patent Document 1, a part of Mn of hexagonal MnBi is substituted with Ni. It has been proposed to stabilize the crystal structure electrochemically and prevent decomposition in a corrosive environment. Patent Document 2 proposes to improve the corrosion resistance by adding an alkaline earth metal such as Sr to MnBi magnetic powder.
　特許文献３ではＭｎＢｉ磁性粉末に、アミン、アミド、イミド等の窒素原子が含まれるカチオン系活性剤または両性活性剤を吸着させて酸化分解を防止し、飽和磁化の低下を抑制することが提案されている。 Patent Document 3 proposes to adsorb a cationic activator or amphoteric activator containing nitrogen atoms such as amine, amide, imide, etc. to MnBi magnetic powder to prevent oxidative degradation and to suppress a decrease in saturation magnetization. ing.
特開平９－１３９３０４号公報JP-A-9-139304 特開２００１－２５７１１０号公報JP 2001-257110 A 特開平９－７１６３号公報Japanese Patent Laid-Open No. 9-7163
　しかしながら、従来の技術ではＭｎＢｉ系磁性粉末の耐食性は十分ではなく、特に高温高湿下において飽和磁化が大きく低下する。このため、未だ磁石材料として実用化されるに至っていない。そこで、本発明は、一つの側面において、高温高湿環境下に長期間保管しても、高い飽和磁化を維持できるＭｎＢｉ系磁性粉末、及びそのようなＭｎＢｉ系磁性粉末を製造する方法を提供することを目的とする。 However, the corrosion resistance of the MnBi-based magnetic powder is not sufficient with the conventional technology, and the saturation magnetization is greatly reduced particularly under high temperature and high humidity. For this reason, it has not yet been put into practical use as a magnet material. Therefore, in one aspect, the present invention provides a MnBi-based magnetic powder that can maintain high saturation magnetization even when stored in a high-temperature, high-humidity environment for a long period of time, and a method for producing such a MnBi-based magnetic powder. For the purpose.
　また、本発明は、別の側面において、高温高湿環境下に長期間保管しても、高い飽和磁化を維持できるボンド磁石、及び、そのようなボンド磁石を製造することが可能なボンド磁石用コンパウンドを提供することを目的とする。本発明は、さらに別の側面において、高温高湿環境下に長期間保管しても、高い飽和磁化を維持できる金属磁石を提供することを目的とする。 In another aspect, the present invention provides a bonded magnet that can maintain high saturation magnetization even when stored in a high-temperature and high-humidity environment for a long period of time, and a bonded magnet that can manufacture such a bonded magnet. The purpose is to provide a compound. Another object of the present invention is to provide a metal magnet that can maintain high saturation magnetization even when stored in a high temperature and high humidity environment for a long period of time.
　これまでのＭｎＢｉ磁性粉末は、高温高湿環境下に保管すると、急速に酸化腐食が進行し、これが飽和磁化の低下の要因となっていた。これは、主として、ＭｎＢｉ磁性粉末に含まれる六方晶ＭｎＢｉ磁性相の耐酸化性の低さに起因していることが分かった。そこで、本発明者らは、六方晶ＭｎＢｉ磁性相の耐酸化性を改善するために、鋭意検討を行った。その結果、六方晶ＭｎＢｉ磁性相に所定の含有量のＺｎを含有させることが有効であることが分かった。本発明は、このような知見に基づいてなされたものであり、一つの側面において、六方晶ＭｎＢｉ磁性相を含有し、六方晶ＭｎＢｉ磁性相におけるＺｎの含有量が０．５～８質量％であるＭｎＢｉ系磁性粉末を提供する。 <Previous MnBi magnetic powders, when stored in a high-temperature and high-humidity environment, rapidly undergoes oxidative corrosion, which caused a decrease in saturation magnetization. It was found that this was mainly due to the low oxidation resistance of the hexagonal MnBi magnetic phase contained in the MnBi magnetic powder. Therefore, the present inventors have intensively studied to improve the oxidation resistance of the hexagonal MnBi magnetic phase. As a result, it has been found that it is effective to contain a predetermined content of Zn in the hexagonal MnBi magnetic phase. The present invention has been made based on such findings. In one aspect, the present invention includes a hexagonal MnBi magnetic phase, and the content of Zn in the hexagonal MnBi magnetic phase is 0.5 to 8% by mass. An MnBi magnetic powder is provided.
　上述のＭｎＢｉ系磁性粉末は、耐酸化性が低い六方晶ＭｎＢｉ磁性相に、０．５～８質量％のＺｎを含有する。これによって、高温高湿環境下における六方晶ＭｎＢｉ磁性相の耐酸化性が向上すると推定される。その結果、ＭｎＢｉ系磁性粉末は、高温高湿環境下に長期間保管しても高い飽和磁化を維持することができる。 The above MnBi magnetic powder contains 0.5 to 8% by mass of Zn in the hexagonal MnBi magnetic phase having low oxidation resistance. This is presumed to improve the oxidation resistance of the hexagonal MnBi magnetic phase in a high temperature and high humidity environment. As a result, the MnBi magnetic powder can maintain high saturation magnetization even when stored for a long time in a high temperature and high humidity environment.
　本発明は、別の側面において、ＭｎＢｉ合金粉末とＺｎ粉末とを混合し、真空中、又は減圧下にある不活性ガス雰囲気中において２８０～３８０℃で熱処理して、Ｚｎを含む六方晶ＭｎＢｉ磁性相を含有するＭｎＢｉ系磁性粉末を得る工程を有し、六方晶ＭｎＢｉ磁性相におけるＺｎの含有量が０．５～８質量％である、ＭｎＢｉ系磁性粉末の製造方法を提供する。 In another aspect, the present invention provides a hexagonal MnBi magnetic material containing Zn by mixing MnBi alloy powder and Zn powder and heat-treating them at 280 to 380 ° C. in an inert gas atmosphere under vacuum or reduced pressure. There is provided a method for producing an MnBi-based magnetic powder comprising a step of obtaining a MnBi-based magnetic powder containing a phase, wherein the content of Zn in the hexagonal MnBi magnetic phase is 0.5 to 8% by mass.
　上述のＭｎＢｉ系磁性粉末の製造方法では、ＭｎＢｉ合金粉末とＺｎ粉末との混合物を、真空中、又は減圧下にある不活性ガス雰囲気中において２８０～３８０℃に加熱している。これによって、Ｚｎが気化して、六方晶ＭｎＢｉ磁性相の内部にＺｎが拡散され、Ｚｎの含有量が０．５～８質量％である六方晶ＭｎＢｉ磁性相を得ている。このようにして得られる六方晶ＭｎＢｉ磁性相は、高温高湿環境下における耐酸化性が向上すると推定される。その結果、上記製造方法によって得られるＭｎＢｉ系磁性粉末は、高温高湿環境下に長期間保管しても高い飽和磁化を維持することができる。 In the MnBi-based magnetic powder manufacturing method described above, a mixture of MnBi alloy powder and Zn powder is heated to 280 to 380 ° C. in a vacuum or in an inert gas atmosphere under reduced pressure. Thereby, Zn is vaporized, Zn is diffused into the hexagonal MnBi magnetic phase, and a hexagonal MnBi magnetic phase having a Zn content of 0.5 to 8% by mass is obtained. The hexagonal MnBi magnetic phase thus obtained is presumed to have improved oxidation resistance in a high temperature and high humidity environment. As a result, the MnBi-based magnetic powder obtained by the above production method can maintain high saturation magnetization even when stored for a long time in a high temperature and high humidity environment.
　本発明は、さらに別の側面において、ＭｎＢｉＺｎ合金を溶融急冷して得られた急冷薄帯の熱処理及び粉砕を行って、Ｚｎを含む六方晶ＭｎＢｉ磁性相を含有するＭｎＢｉ系磁性粉末を得る工程を有し、六方晶ＭｎＢｉ磁性相におけるＺｎの含有量が０．５～８質量％である、ＭｎＢｉ系磁性粉末の製造方法を提供する。 In yet another aspect, the present invention provides a process for obtaining a MnBi-based magnetic powder containing a hexagonal MnBi magnetic phase containing Zn by performing heat treatment and pulverization of a quenched ribbon obtained by melting and quenching an MnBiZn alloy. And a method for producing MnBi-based magnetic powder, wherein the content of Zn in the hexagonal MnBi magnetic phase is 0.5 to 8% by mass.
　上述のＭｎＢｉ系磁性粉末の製造方法では、溶融急冷した後、熱処理及び粉砕することによって、六方晶ＭｎＢｉ磁性相におけるＺｎの含有量が０．５～８質量％であるＭｎＢｉ系磁性粉末を得ている。このようなＭｎＢｉ系磁性粉末は、高温高湿環境下に長期間保管しても高い飽和磁化を維持することができる。なお、熱処理及び粉砕は、どちらを先に行ってもよい。熱処理は、不活性ガス雰囲気中において２８０～３８０℃で行うことが好ましい。 In the MnBi magnetic powder manufacturing method described above, MnBi magnetic powder having a Zn content of 0.5 to 8% by mass in the hexagonal MnBi magnetic phase is obtained by melting and quenching, followed by heat treatment and pulverization. Yes. Such MnBi-based magnetic powder can maintain high saturation magnetization even when stored for a long time in a high temperature and high humidity environment. Either heat treatment or pulverization may be performed first. The heat treatment is preferably performed at 280 to 380 ° C. in an inert gas atmosphere.
　本発明は、さらに別の側面において、上述のＭｎＢｉ系磁性粉末と樹脂バインダとを含む混練物からなるボンド磁石用コンパウンド、及び、上述のＭｎＢｉ系磁性粉末と樹脂バインダとを含むボンド磁石を提供する。このようなコンパウンド及びボンド磁石は、上述の特徴を有するＭｎＢｉ系磁性粉末を含有することから、高温高湿環境下に長期間保管しても高い飽和磁化を維持することができる。 In still another aspect, the present invention provides a bonded magnet compound comprising a kneaded material containing the above-described MnBi-based magnetic powder and a resin binder, and a bonded magnet including the above-described MnBi-based magnetic powder and a resin binder. . Since such a compound and bond magnet contain the MnBi magnetic powder having the above-described characteristics, high saturation magnetization can be maintained even if stored for a long time in a high temperature and high humidity environment.
　本発明は、さらに別の側面において、Ｚｎを含有する六方晶ＭｎＢｉ磁性相を含有し、上記六方晶ＭｎＢｉ磁性相における、Ｍｎ、Ｂｉ及びＺｎの合計に対するＺｎの含有量が０．５～８質量％である、金属磁石を提供する。この金属磁石は、上述のＭｎＢｉ系磁性粉末を加圧成形して作製した成形体を、熱処理又は焼結して得ることができる。このような金属磁石は、耐酸化性が低い六方晶ＭｎＢｉ磁性相に、０．５～８質量％のＺｎを含有する。これによって、高温高湿環境下における六方晶ＭｎＢｉ磁性相の耐酸化性が向上すると推定される。その結果、金属磁石は、高温高湿環境下に長期間保管しても高い飽和磁化を維持することができる。 In still another aspect, the present invention includes a hexagonal MnBi magnetic phase containing Zn, and the content of Zn in the hexagonal MnBi magnetic phase is 0.5 to 8 mass relative to the total of Mn, Bi and Zn. %, Provide a metal magnet. This metal magnet can be obtained by heat-treating or sintering a molded body produced by pressure-molding the above-described MnBi-based magnetic powder. Such a metal magnet contains 0.5 to 8% by mass of Zn in a hexagonal MnBi magnetic phase having low oxidation resistance. This is presumed to improve the oxidation resistance of the hexagonal MnBi magnetic phase in a high temperature and high humidity environment. As a result, the metal magnet can maintain high saturation magnetization even if stored for a long time in a high temperature and high humidity environment.
　本発明によれば、高温高湿環境下に長期間保管しても、高い飽和磁化を維持できるＭｎＢｉ系磁性粉末、及びそのようなＭｎＢｉ系磁性粉末を製造する方法を提供することができる。また、本発明は、高温高湿環境下に長期間保管しても、高い飽和磁化を維持できるボンド磁石、及び、そのようなボンド磁石を製造することが可能なボンド磁石用コンパウンドを提供することができる。さらに、本発明は、高温高湿環境下に長期間保管しても、高い飽和磁化を維持できる金属磁石を提供することができる。 According to the present invention, it is possible to provide a MnBi-based magnetic powder capable of maintaining high saturation magnetization even when stored in a high-temperature and high-humidity environment for a long period of time, and a method for producing such MnBi-based magnetic powder. The present invention also provides a bonded magnet that can maintain a high saturation magnetization even when stored in a high temperature and high humidity environment for a long period of time, and a bonded magnet compound capable of producing such a bonded magnet. Can do. Furthermore, the present invention can provide a metal magnet that can maintain high saturation magnetization even when stored in a high temperature and high humidity environment for a long period of time.
図１（Ａ）は、ＭｎＢｉ系磁性粉末の断面の一部を拡大して示す電子顕微鏡写真の一例である。図１（Ｂ）は、図１（Ａ）の電子顕微鏡写真に写し出された断面構造を模式的に示す図である。FIG. 1A is an example of an electron micrograph showing an enlarged part of the cross section of the MnBi-based magnetic powder. FIG. 1B is a diagram schematically showing a cross-sectional structure shown in the electron micrograph of FIG. 図２（Ａ）は、ＭｎＢｉ系磁性粉末の断面の一部を拡大して示す電子顕微鏡写真の別の例である。図２（Ｂ）は、図２（Ａ）の電子顕微鏡写真において線分析（ＥＤＸ分析）を行った結果を示す図である。FIG. 2A is another example of an electron micrograph showing an enlarged part of a cross section of the MnBi-based magnetic powder. FIG. 2B is a diagram showing a result of performing line analysis (EDX analysis) in the electron micrograph of FIG. 図３は、ＭｎＢｉ系磁性粉末、ボンド磁石、及び金属磁石を製造する方法の一具体例を示すフローチャートである。FIG. 3 is a flowchart showing a specific example of a method for producing an MnBi-based magnetic powder, a bonded magnet, and a metal magnet. 図４は、ＭｎＢｉ系磁性粉末、ボンド磁石、及び金属磁石を製造する方法の別の具体例を示すフローチャートである。FIG. 4 is a flowchart showing another specific example of a method for producing an MnBi-based magnetic powder, a bonded magnet, and a metal magnet. 図５は、ＭｎＢｉ系磁性粉末、ボンド磁石、及び金属磁石を製造する方法のさらに別の具体例を示すフローチャートである。FIG. 5 is a flowchart showing still another specific example of a method for producing an MnBi-based magnetic powder, a bond magnet, and a metal magnet. 図６は、ＭｎＢｉ系金属磁石の一実施形態を示す斜視図である。FIG. 6 is a perspective view showing an embodiment of the MnBi-based metal magnet.
　本発明の一実施形態を、場合により図面を参照しながら詳細に説明する。なお、以下の実施形態は、本発明を説明するための例示であり、本発明を以下の内容に限定する趣旨ではない。 An embodiment of the present invention will be described in detail with reference to the drawings in some cases. In addition, the following embodiment is an illustration for demonstrating this invention, and is not the meaning which limits this invention to the following content.
　本実施形態のＭｎＢｉ系磁性粉末は、主成分として六方晶ＭｎＢｉ磁性相を含有する。六方晶ＭｎＢｉ磁性相のほかに、副成分としてＢｉ相及びＭｎ相の少なくとも一方を含有してもよい。Ｍｎ相は、Ｍｎ及びＭｎ酸化物から形成される。Ｂｉ相は、Ｂｉから形成される。ＭｎＢｉ系磁性粉末は、Ｂｉ相を含有することによって、磁場中熱処理時に六方晶ＭｎＢｉ磁性相の配向性が良好となり、異方性の高い磁石粉末を容易に得ることができる。ＭｎＢｉ系磁性粉末におけるＭｎ及びＢｉの合計含有量は、例えば、９０質量％以上であってもよく、９４質量％以上であってもよい。 The MnBi magnetic powder of the present embodiment contains a hexagonal MnBi magnetic phase as a main component. In addition to the hexagonal MnBi magnetic phase, at least one of a Bi phase and a Mn phase may be contained as a subcomponent. The Mn phase is formed from Mn and Mn oxide. The Bi phase is formed from Bi. When the MnBi magnetic powder contains the Bi phase, the orientation of the hexagonal MnBi magnetic phase is improved during heat treatment in a magnetic field, and a highly anisotropic magnet powder can be easily obtained. The total content of Mn and Bi in the MnBi magnetic powder may be, for example, 90% by mass or more, or 94% by mass or more.
　ＭｎとＢｉの合計に対するＭｎの含有比率は、好ましくは３５～６５ｍｏｌ％であり、より好ましくは３７．５～５０ｍｏｌ％である。Ｍｎの含有比率が低くなり過ぎると、Ｍｎが不足して六方晶ＭｎＢｉ磁性相の割合が低下し、磁化の値が低下する傾向にある。一方、Ｍｎの含有比率が高くなり過ぎると、Ｂｉが不足して六方晶ＭｎＢｉ磁性相の割合が低下し、磁化の値が低下する傾向にある。また、Ｂｉ相の割合が少なくなって、磁場中熱処理での異方化が不十分となる傾向にある。また、余剰のＭｎが存在すると、ＭｎＺｎが形成されやすくなり、ＭｎＢｉ磁性相におけるＺｎ含有量が減少する傾向にある。 The content ratio of Mn to the total of Mn and Bi is preferably 35 to 65 mol%, more preferably 37.5 to 50 mol%. When the content ratio of Mn becomes too low, Mn is insufficient, the ratio of the hexagonal MnBi magnetic phase decreases, and the magnetization value tends to decrease. On the other hand, when the content ratio of Mn becomes too high, Bi is insufficient, the ratio of the hexagonal MnBi magnetic phase decreases, and the magnetization value tends to decrease. Further, the proportion of the Bi phase decreases, and the anisotropy in the heat treatment in the magnetic field tends to be insufficient. Moreover, when there exists excess Mn, it will become easy to form MnZn and it exists in the tendency for Zn content in a MnBi magnetic phase to reduce.
　ＭｎＢｉ系磁性粉末におけるＺｎの含有量は、高い磁気特性を維持しつつ耐食性を向上する観点から、例えば０．３～５質量％であってもよく、０．４～４質量％であってもよい。ＭｎＢｉ系磁性粉末の平均粒径は、例えば３～１５０μmである。 From the viewpoint of improving corrosion resistance while maintaining high magnetic properties, the Zn content in the MnBi-based magnetic powder may be, for example, 0.3 to 5% by mass, or 0.4 to 4% by mass. Good. The average particle diameter of the MnBi magnetic powder is, for example, 3 to 150 μm.
　図１（Ａ）は、本実施形態のＭｎＢｉ系磁性粉末を樹脂包埋し、クロスセクションポリッシャーによって研磨して得られた断面の一部を拡大して示す電子顕微鏡写真の一例である。図１（Ｂ）は、図１（Ａ）の電子顕微鏡写真に写し出された断面構造を模式的に示す図である。 FIG. 1 (A) is an example of an electron micrograph showing an enlarged part of a cross section obtained by embedding a MnBi-based magnetic powder of the present embodiment in a resin and polishing it with a cross section polisher. FIG. 1B is a diagram schematically showing a cross-sectional structure shown in the electron micrograph of FIG.
　図１（Ａ）及び図１（Ｂ）に示されるように、ＭｎＢｉ系磁性粉末は、六方晶ＭｎＢｉ磁性相１０と、これに隣接するＢｉ相２０とを含有する。図１（Ａ）及び図１（Ｂ）には、ＭｎＢｉ系磁性粉末を包埋するために用いられた樹脂３０も写し出されている。 As shown in FIGS. 1 (A) and 1 (B), the MnBi-based magnetic powder contains a hexagonal MnBi magnetic phase 10 and a Bi phase 20 adjacent thereto. 1A and 1B also show the resin 30 used for embedding the MnBi magnetic powder.
　六方晶ＭｎＢｉ磁性相１０は、Ｍｎ及びＢｉに加えて、Ｚｎを含有する。六方晶ＭｎＢｉ磁性相１０におけるＺｎの含有量は、０．５～８質量％であり、好ましくは０．９～６質量％である。このＺｎの含有量が過小になると、優れた耐食性が損なわれる傾向にある。一方、このＺｎの含有量が過大になると、非磁性成分が増加して磁化の値が低下する傾向にある。 The hexagonal MnBi magnetic phase 10 contains Zn in addition to Mn and Bi. The content of Zn in the hexagonal MnBi magnetic phase 10 is 0.5 to 8% by mass, preferably 0.9 to 6% by mass. When the Zn content is too low, excellent corrosion resistance tends to be impaired. On the other hand, when the Zn content is excessive, the nonmagnetic component increases and the magnetization value tends to decrease.
　図２（Ａ）は、本実施形態のＭｎＢｉ系磁性粉末を樹脂包埋し、クロスセクションポリッシャーによって研磨して得られた断面の一部を拡大して示す電子顕微鏡写真の別の例である。図２（Ｂ）は、図２（Ａ）の電子顕微鏡写真において点ａを開始点として線分に沿って、線分析（ＥＤＸ分析）を行った結果を示す図である。 FIG. 2 (A) is another example of an electron micrograph showing an enlarged part of a cross section obtained by embedding the MnBi-based magnetic powder of the present embodiment in a resin and polishing it with a cross section polisher. FIG. 2B is a diagram illustrating a result of performing line analysis (EDX analysis) along the line segment with the point a as a starting point in the electron micrograph of FIG.
　図２（Ａ）に示されるように、ＭｎＢｉ系磁性粉末は、六方晶ＭｎＢｉ磁性相１０と、これを挟むように、Ｂｉ相２０，２０とを含有する。図２（Ｂ）に示される線分析によれば、六方晶ＭｎＢｉ磁性相１０には、Ｍｎ，Ｂｉ，及びＺｎが含まれている。一方、Ｂｉ相２０には、Ｍｎ及びＺｎが実質的に含まれていない。 As shown in FIG. 2 (A), the MnBi-based magnetic powder contains a hexagonal MnBi magnetic phase 10 and Bi phases 20 and 20 so as to sandwich this. According to the line analysis shown in FIG. 2B, the hexagonal MnBi magnetic phase 10 contains Mn, Bi, and Zn. On the other hand, the Bi phase 20 is substantially free of Mn and Zn.
　図２（Ａ）及び図２（Ｂ）に示すように、ＭｎＢｉ系磁性粉末の六方晶ＭｎＢｉ磁性相１０にＺｎを偏在させることによって、非磁性成分の割合を低く維持しつつ、六方晶ＭｎＢｉ磁性相１０の耐食性を効果的に向上させることができる。このような観点から、Ｂｉ相２０におけるＺｎの含有量は、例えば０．０１質量％以下である。同様の観点から、Ｍｎ相におけるＺｎの含有量は、例えば１０質量％以下である。 As shown in FIGS. 2 (A) and 2 (B), the hexagonal MnBi magnetism is maintained while keeping the ratio of nonmagnetic components low by allowing Zn to be unevenly distributed in the hexagonal MnBi magnetic phase 10 of the MnBi-based magnetic powder. The corrosion resistance of the phase 10 can be effectively improved. From such a viewpoint, the Zn content in the Bi phase 20 is, for example, 0.01% by mass or less. From the same viewpoint, the Zn content in the Mn phase is, for example, 10% by mass or less.
　ＭｎＢｉ系磁性粉末における六方晶ＭｎＢｉ磁性相１０の割合は、図１（Ａ）及び図２（Ａ）に示すような断面の電子顕微鏡写真における面積比率として、例えば６０～９８％であってもよく、７０～９５％であってもよい。この面積比率が低くなり過ぎると、非磁性相の割合が高くなって飽和磁化の値が低くなる傾向にある。一方、この面積比率が高くなり過ぎると、例えば、粒子が単磁区のサイズよりも大きい場合に、磁場中熱処理を行って磁石粉末を得る際に溶解するＢｉ相２０が少なくなる。これによって、磁場中熱処理時に六方晶ＭｎＢｉ磁性相１０が配向し難くなる傾向にある。ただし、粒子が単磁区サイズとほぼ同じである場合には、六方晶ＭｎＢｉ磁性相１０を粒子内で配向させる必要がないことから、六方晶ＭｎＢｉ磁性相１０の割合は高くてもよい。 The ratio of the hexagonal MnBi magnetic phase 10 in the MnBi-based magnetic powder may be, for example, 60 to 98% as an area ratio in a cross-sectional electron micrograph as shown in FIGS. 1 (A) and 2 (A). 70-95%. If the area ratio is too low, the ratio of the nonmagnetic phase tends to increase and the saturation magnetization value tends to decrease. On the other hand, if this area ratio becomes too high, for example, when the particles are larger than the size of the single magnetic domain, the Bi phase 20 that dissolves when the magnetic powder is obtained by performing the heat treatment in the magnetic field decreases. This tends to make it difficult for the hexagonal MnBi magnetic phase 10 to be oriented during heat treatment in a magnetic field. However, when the particles are substantially the same as the single magnetic domain size, the ratio of the hexagonal MnBi magnetic phase 10 may be high because it is not necessary to orient the hexagonal MnBi magnetic phase 10 within the particle.
　本実施形態のＭｎＢｉ系磁性粉末は、磁場中熱処理が施された磁石粉末であってもよい。本実施形態のＭｎＢｉ系磁性粉末は、六方晶ＭｎＢｉ磁性相が、高い耐酸化性を有する。このため、ＭｎＢｉ系磁性粉末は、高温高湿環境下に長期間保管しても飽和磁化の低下を少なくすることができる。このようなＭｎＢｉ系磁性粉末を用いて形成されたボンド磁石及び金属磁石は、高温高湿環境下に長期間保管しても飽和磁化の低下を少なくすることができる。次に、ＭｎＢｉ系磁性粉末の製造方法の幾つかの実施形態を以下に説明する。 The MnBi magnetic powder of this embodiment may be a magnet powder that has been heat-treated in a magnetic field. In the MnBi magnetic powder of this embodiment, the hexagonal MnBi magnetic phase has high oxidation resistance. For this reason, the MnBi-based magnetic powder can reduce the decrease in saturation magnetization even when stored for a long time in a high temperature and high humidity environment. Bond magnets and metal magnets formed using such MnBi-based magnetic powder can reduce the decrease in saturation magnetization even when stored for a long time in a high temperature and high humidity environment. Next, some embodiments of the method for producing the MnBi-based magnetic powder will be described below.
　一実施形態に係るＭｎＢｉ系磁性粉末の製造方法は、ＭｎＢｉ合金粉末を得る工程と、ＭｎＢｉ合金粉末とＺｎ粉末とを含む混合粉末を、減圧下において２８０～３８０℃に加熱して、六方晶ＭｎＢｉ磁性相を生成させるとともに、六方晶ＭｎＢｉ磁性相の内部にＺｎを拡散させ、六方晶ＭｎＢｉ磁性相におけるＺｎの含有量が０．５～８質量％であるＭｎＢｉ系磁性粉末を得る工程とを有する。このように、主成分としてＭｎＢｉを含み、副成分としてＺｎ等を含む磁性粉末を、本明細書ではＭｎＢｉ系磁性粉末という。 According to one embodiment, a method for producing an MnBi-based magnetic powder includes a step of obtaining an MnBi alloy powder, and heating a mixed powder containing the MnBi alloy powder and the Zn powder to 280 to 380 ° C. under reduced pressure to obtain a hexagonal MnBi Forming a magnetic phase and diffusing Zn inside the hexagonal MnBi magnetic phase to obtain a MnBi-based magnetic powder having a Zn content of 0.5 to 8 mass% in the hexagonal MnBi magnetic phase. . Thus, magnetic powder containing MnBi as a main component and Zn or the like as a subcomponent is referred to as MnBi-based magnetic powder in this specification.
　ＭｎＢｉ合金粉末は、(i)Ｍｎ及びＢｉを粉砕して焼結した後に粉砕することによりＭｎＢｉ合金粉末を得る粉末冶金法、(ii)ＭｎＢｉ合金を溶融してアトマイズすることによりＭｎＢｉ合金粉末を得るアトマイズ法、(iii)アーク炉で溶融して得たＭｎＢｉ合金塊を粉砕することによりＭｎＢｉ合金粉末を得る溶融法、(iv)溶融したＭｎＢｉ合金をロールで急冷し、得られた急冷薄帯を粉砕することによりＭｎＢｉ合金粉末を得る液体急冷法、を用いて製造することができる。各方法において、Ｍｎ原料及びＢｉ原料としては、チップ、ショット又は粉末などを適宜選択して用いることができる。また、Ｚｎ原料も、チップ、ショット又は粉末などを適宜選択して用いることができる。 MnBi alloy powder is obtained by (i) powder metallurgy method for obtaining MnBi alloy powder by crushing and sintering Mn and Bi, and (ii) obtaining MnBi alloy powder by melting and atomizing MnBi alloy. Atomizing method, (iii) Melting method to obtain MnBi alloy powder by pulverizing MnBi alloy lump obtained by melting in an arc furnace, (iv) Quenching the molten MnBi alloy with a roll, It can be manufactured using a liquid quenching method in which MnBi alloy powder is obtained by pulverization. In each method, a chip, a shot, a powder, or the like can be appropriately selected and used as the Mn raw material and the Bi raw material. In addition, as a Zn raw material, a chip, a shot, a powder, or the like can be appropriately selected and used.
　上述の(i)～(iv)の方法のうち、(iv)の液体急冷法が好ましい。（iv）の液体急冷法では、溶融合金をロールで急冷して得られる急冷薄帯を粉砕することによって、粒径が十分に小さいＭｎＢｉ合金粉末を得ることができる。これによって、熱処理工程においてＺｎを六方晶ＭｎＢｉ磁性相の内部まで十分に拡散させることができる。 Among the methods (i) to (iv) described above, the liquid quenching method (iv) is preferable. In the liquid quenching method (iv), an MnBi alloy powder having a sufficiently small particle size can be obtained by pulverizing a quenched ribbon obtained by quenching a molten alloy with a roll. Thus, Zn can be sufficiently diffused into the hexagonal MnBi magnetic phase in the heat treatment step.
　図３は、ＭｎＢｉ系磁性粉末、ボンド磁石用コンパウンド、ボンド磁石、及び金属磁石の製造方法の具体例を示すフローチャートである。この例では、上述の(iv)液体急冷法を用いてＭｎＢｉ合金粉末を調製している。すなわち、まず、Ｍｎ原料及びＢｉ原料を準備して、例えばアーク溶解等によって、ＭｎＢｉ合金を溶製（溶解鋳造）する溶製工程Ｓ１を行う。その後、液体急冷法によって急冷薄帯を得る液体急冷工程Ｓ２を行う。続いて、得られた急冷薄帯を粗粉砕する粗粉砕工程Ｓ３を行って、ＭｎＢｉ合金粉末を得る。 FIG. 3 is a flowchart showing a specific example of a method for producing MnBi-based magnetic powder, a compound for bonded magnet, a bonded magnet, and a metal magnet. In this example, the MnBi alloy powder is prepared using the above (iv) liquid quenching method. That is, first, a Mn raw material and a Bi raw material are prepared, and a melting step S1 for melting (melting casting) the MnBi alloy by, for example, arc melting or the like is performed. Thereafter, a liquid quenching step S2 for obtaining a quenched ribbon by a liquid quenching method is performed. Subsequently, a coarse pulverization step S3 for coarsely pulverizing the obtained quenched ribbon is performed to obtain an MnBi alloy powder.
　混合工程Ｓ４では、上述のようにして得られたＭｎＢｉ合金粉末とＺｎ粉末とを混合する。このときの混合比は、ＭｎＢｉ合金粉末に対して、Ｚｎ粉末を１～１０質量％混合する。熱処理工程では、Ｚｎ粉末が気化する条件で行うため、目標とするＭｎＢｉ系磁性粉末のＺｎ含有量よりも、Ｚｎ粉末を多めに混合することが好ましい。 In the mixing step S4, the MnBi alloy powder and the Zn powder obtained as described above are mixed. The mixing ratio at this time is such that 1 to 10% by mass of Zn powder is mixed with MnBi alloy powder. In the heat treatment step, since Zn powder is vaporized, it is preferable to mix more Zn powder than the Zn content of the target MnBi magnetic powder.
　熱処理工程Ｓ５では、ＭｎＢｉ合金粉末とＺｎ粉末の混合粉末を、真空中、又は減圧下（好ましくは１０Ｐａ以下）にある不活性ガス雰囲気中、２８０～３８０℃（好ましくは３００～３７０℃）で、３０～２００分間加熱する。不活性ガスとしては、アルゴンガス、窒素ガス等が挙げられる。このような加熱条件で熱処理を施すことによって、気化したＺｎがＭｎＢｉ粒子の表面から六方晶ＭｎＢｉ相の内部に拡散する。このようにして、Ｚｎを所定量含有する六方晶ＭｎＢｉ磁性相を有するＭｎＢｉ系磁性粉末が得られる。 In the heat treatment step S5, the mixed powder of the MnBi alloy powder and the Zn powder is 280 to 380 ° C. (preferably 300 to 370 ° C.) in vacuum or in an inert gas atmosphere under reduced pressure (preferably 10 Pa or less). Heat for 30-200 minutes. Examples of the inert gas include argon gas and nitrogen gas. By performing a heat treatment under such heating conditions, vaporized Zn diffuses from the surface of the MnBi particles into the hexagonal MnBi phase. In this way, an MnBi magnetic powder having a hexagonal MnBi magnetic phase containing a predetermined amount of Zn is obtained.
　上述の加熱条件における加熱温度が２８０℃未満では、Ｚｎが十分に気化しないことから、熱処理工程Ｓ５が長くなる傾向にある。また、六方晶ＭｎＢｉ磁性相が十分に生成しない傾向にある。一方、当該加熱温度が３８０℃を超えると、六方晶ＭｎＢｉ磁性相の強磁性低温相から常磁性高温相への構造相転移が生じ、強磁性が消失する傾向にある。また、Ｂｉが溶解してＢｉ相が析出するため、六方晶ＭｎＢｉ磁性相の割合が低下して飽和磁化の値が低下する傾向にある。上記加熱条件の処理時間が短過ぎるとＺｎの拡散が十分に進行せず、十分な耐食性向上効果が得られない場合がある。また、六方晶ＭｎＢｉ磁性相が十分に生成しない傾向にある。一方、当該処理時間が長くなり過ぎると、六方晶ＭｎＢｉ磁性相が成長して保磁力が低下する傾向にある。 When the heating temperature under the above heating conditions is less than 280 ° C., Zn is not sufficiently vaporized, so that the heat treatment step S5 tends to be long. Further, the hexagonal MnBi magnetic phase tends not to be generated sufficiently. On the other hand, when the heating temperature exceeds 380 ° C., the structural phase transition of the hexagonal MnBi magnetic phase from the ferromagnetic low temperature phase to the paramagnetic high temperature phase occurs, and the ferromagnetism tends to disappear. Further, since Bi dissolves and the Bi phase precipitates, the ratio of the hexagonal MnBi magnetic phase tends to decrease and the saturation magnetization value tends to decrease. If the treatment time under the above heating conditions is too short, Zn diffusion does not proceed sufficiently, and a sufficient corrosion resistance improvement effect may not be obtained. Further, the hexagonal MnBi magnetic phase tends not to be generated sufficiently. On the other hand, if the treatment time is too long, the hexagonal MnBi magnetic phase grows and the coercive force tends to decrease.
　上述の製造方法によって得られるＭｎＢｉ系磁性粉末における六方晶ＭｎＢｉ磁性相は、高い耐酸化性を有する。このため、ＭｎＢｉ系磁性粉末は、高温高湿環境下に長期間保管しても飽和磁化の低下を少なくすることができる。 The hexagonal MnBi magnetic phase in the MnBi-based magnetic powder obtained by the above-described manufacturing method has high oxidation resistance. For this reason, the MnBi-based magnetic powder can reduce the decrease in saturation magnetization even when stored for a long time in a high temperature and high humidity environment.
　熱処理工程Ｓ５の後に、磁場中熱処理工程Ｓ６を行う。磁場中熱処理工程Ｓ６は、ＭｎＢｉ系磁性粉末に例えば０．４～０．８Ｔ（４０００～８０００Ｇ）の磁場を印加しながら、２６０～３８０℃の温度で３０～６００分間加熱することによって行うことができる。このような磁場中熱処理工程Ｓ６を行うことによって、異方性の磁石粉末を得ることができる。 After the heat treatment step S5, a magnetic field heat treatment step S6 is performed. The magnetic field heat treatment step S6 is performed by heating the MnBi magnetic powder at a temperature of 260 to 380 ° C. for 30 to 600 minutes while applying a magnetic field of 0.4 to 0.8 T (4000 to 8000 G), for example. it can. By performing such a heat treatment step S6 in a magnetic field, anisotropic magnet powder can be obtained.
　磁場中熱処理工程Ｓ６における加熱温度が低過ぎると、十分に異方化し難くなる傾向がある。一方、当該加熱温度が高過ぎると、六方晶ＭｎＢｉ磁性相の強磁性低温相から常磁性高温相への構造相転移が生じ、強磁性が消失する傾向にある。磁場中熱処理工程Ｓ６における加熱時間が短過ぎると、十分に異方化し難くなる傾向がある。一方、当該加熱時間は、６００分間程度行えば十分であり、これ以上長くしても効果は殆どない。 If the heating temperature in the heat treatment step S6 in a magnetic field is too low, there is a tendency that it is difficult to be anisotropic enough. On the other hand, if the heating temperature is too high, a structural phase transition of the hexagonal MnBi magnetic phase from the ferromagnetic low temperature phase to the paramagnetic high temperature phase occurs, and the ferromagnetism tends to disappear. If the heating time in the heat treatment step S6 in the magnetic field is too short, there is a tendency that it is difficult to be anisotropic enough. On the other hand, it is sufficient that the heating time is about 600 minutes.
　磁場中熱処理工程Ｓ６の後に、粉砕工程Ｓ７を行って、所望の粒径を有する異方性の磁石粉末としてもよい。ただし、このような手順に限定されず、例えば、熱処理工程Ｓ５で十分に六方晶ＭｎＢｉ磁性相を生成した後、磁場中熱処理工程Ｓ６を行うことなく、粉砕工程Ｓ７において粒子を単磁区サイズにまで粉砕して、異方性の磁石粉末を得てもよい。 It is good also as anisotropic magnet powder which has desired particle size by performing crushing process S7 after heat processing process S6 in a magnetic field. However, the present invention is not limited to such a procedure. For example, after the hexagonal MnBi magnetic phase is sufficiently generated in the heat treatment step S5, the particles are reduced to a single domain size in the pulverization step S7 without performing the heat treatment step S6 in the magnetic field. An anisotropic magnet powder may be obtained by pulverization.
　続いて、異方性の磁石粉末の磁場中成形を行って成形体を作製する磁場中成形工程Ｓ８を行う。印加する磁場は例えば０．４～０．８Ｔ（４０００～８０００Ｇ）であり、成形圧は例えば１～１０ｔ／ｃｍ２である。続いて、得られた成形体を、不活性ガス雰囲気中、２００～３８０℃の温度で１～１０時間加熱する熱処理工程Ｓ９を行う。もしくは、熱処理工程Ｓ９に代えて、加熱しながら加圧する熱間圧縮工程を行ってもよい。これによって、異方性のＭｎＢｉ系金属磁石を製造することができる。このように、ＭｎＢｉ系磁性粉末を用いて得られたＭｎＢｉ系金属磁石は、高温高湿環境下で用いても、高い飽和磁化を維持することができる。 Subsequently, an in-magnetic field forming step S8 is performed in which anisotropic magnet powder is formed in a magnetic field to produce a compact. The applied magnetic field is, for example, 0.4 to 0.8 T (4000 to 8000 G), and the molding pressure is, for example, 1 to 10 t / cm 2 . Subsequently, a heat treatment step S9 is performed in which the obtained molded body is heated at a temperature of 200 to 380 ° C. for 1 to 10 hours in an inert gas atmosphere. Alternatively, instead of the heat treatment step S9, a hot compression step of applying pressure while heating may be performed. Thereby, an anisotropic MnBi-based metal magnet can be manufactured. Thus, the MnBi-based metal magnet obtained using the MnBi-based magnetic powder can maintain high saturation magnetization even when used in a high-temperature and high-humidity environment.
　ＭｎＢｉ系金属磁石は、磁場中熱処理工程Ｓ６を行う前のＭｎＢｉ系磁性粉末を用いて製造してもよい。この場合、ＭｎＢｉ系磁性粉末を、成形して成形体を作製する成形工程Ｓ２０を行う。成形は、１～１０ｔ／ｃｍ２の成形圧で、圧縮成形及び射出成形等の公知の方法で行うことができる。得られた成形体を用いて磁場中焼結工程Ｓ２１を行う。これによって、異方性のＭｎＢｉ系金属磁石を得ることができる。磁場中焼結は、不活性ガス雰囲気中、０．４～０．６Ｔ（４０００～６０００Ｇ）の磁場を印加しながら、２８０～３８０℃の温度で１～１０時間加熱して行うことができる。この製造方法によって得られるＭｎＢｉ系金属磁石も、ＭｎＢｉ系磁性粉末を用いて得られることから、高温高湿環境下で用いても、高い飽和磁化を維持することができる。 You may manufacture a MnBi type | system | group metal magnet using the MnBi type | system | group magnetic powder before performing heat processing process S6 in a magnetic field. In this case, a molding step S20 is performed in which the MnBi-based magnetic powder is molded to produce a molded body. The molding can be performed by a known method such as compression molding or injection molding at a molding pressure of 1 to 10 t / cm 2 . The in-magnetic field sintering step S21 is performed using the obtained molded body. Thereby, an anisotropic MnBi-based metal magnet can be obtained. Sintering in a magnetic field can be performed by heating at a temperature of 280 to 380 ° C. for 1 to 10 hours while applying a magnetic field of 0.4 to 0.6 T (4000 to 6000 G) in an inert gas atmosphere. Since the MnBi-based metal magnet obtained by this manufacturing method is also obtained using the MnBi-based magnetic powder, high saturation magnetization can be maintained even when used in a high temperature and high humidity environment.
　磁石粉末を用いて、ボンド磁石用のコンパウンド及びボンド磁石を作製してもよい。この場合、磁石粉末に、熱可塑性樹脂、カップリング材、及び潤滑材を含む樹脂バインダを添加して混練する混練工程Ｓ１０を行ってもよい。混練して得られたボンド磁石用のコンパウンドを、例えば０．４～０．８Ｔ（４０００～８０００Ｇ）の磁場中で成形する成形工程Ｓ１１を行ってボンド磁石を製造することができる。成形は、１～１０ｔ／ｃｍ２の成形圧で、圧縮成形及び射出成形等の公知の方法で行うことができる。 You may produce the compound and bond magnet for bond magnets using magnet powder. In this case, you may perform kneading | mixing process S10 which adds and knead | mixes the resin powder containing a thermoplastic resin, a coupling material, and a lubricating material to magnet powder. A bonded magnet can be manufactured by performing a molding step S11 in which a compound for a bonded magnet obtained by kneading is molded in a magnetic field of, for example, 0.4 to 0.8 T (4000 to 8000 G). The molding can be performed by a known method such as compression molding or injection molding at a molding pressure of 1 to 10 t / cm 2 .
　樹脂バインダは、エポキシ樹脂等の熱硬化性樹脂であってもよい。この場合、磁石粉末と樹脂バインダとを混練して加圧成形等により成形した後、熱処理を行うことによりボンド磁石を製造することができる。このようにＭｎＢｉ系磁性粉末を用いて得られるボンド磁石は、高温高湿環境下で用いても、飽和磁化の低下を抑制することができる。 The resin binder may be a thermosetting resin such as an epoxy resin. In this case, the magnet powder and the resin binder are kneaded and molded by pressure molding or the like, and then a heat treatment is performed to manufacture a bonded magnet. Thus, the bond magnet obtained by using the MnBi-based magnetic powder can suppress a decrease in saturation magnetization even when used in a high temperature and high humidity environment.
　次に、ＭｎＢｉ系磁性粉末の製造方法の別の実施形態を説明する。本実施形態のＭｎＢｉ系磁性粉末の製造方法は、Ｍｎ原料とＢｉ原料とＺｎ原料とを溶解した後、急冷して急冷薄帯を得る溶融急冷法の後に、急冷薄帯の熱処理及び粉砕を実施することにより、六方晶ＭｎＢｉ磁性相を含有し、六方晶ＭｎＢｉ磁性相におけるＺｎの含有量が０．５～８質量％であるＭｎＢｉ系磁性粉末を得る工程を有する。 Next, another embodiment of the method for producing MnBi magnetic powder will be described. The manufacturing method of the MnBi-based magnetic powder of this embodiment is a method of melting and quenching a Mn raw material, a Bi raw material, and a Zn raw material, followed by a melt quenching method in which a rapidly cooled ribbon is obtained, and then subjecting the quenched ribbon to heat treatment and pulverization Thus, there is a step of obtaining a MnBi-based magnetic powder containing a hexagonal MnBi magnetic phase and having a Zn content of 0.5 to 8% by mass in the hexagonal MnBi magnetic phase.
　図４は、ＭｎＢｉ系磁性粉末の製造方法、及びこの製造方法によって得られるＭｎＢｉ系磁性粉末を用いたボンド磁石用コンパウンド、ボンド磁石、及び金属磁石の製造方法の別の具体例を示すフローチャートである。この例では、Ｍｎ原料及びＢｉ原料を用いて、上記実施形態の(i)～(iv)のいずれかの方法によってＭｎＢｉ合金を調製する調製工程Ｓ３１を行う。 FIG. 4 is a flowchart showing another specific example of a method for producing a MnBi magnetic powder and a method for producing a bonded magnet compound, a bonded magnet, and a metal magnet using the MnBi magnetic powder obtained by the production method. . In this example, a preparation step S31 for preparing a MnBi alloy by any one of the methods (i) to (iv) of the above embodiment is performed using a Mn raw material and a Bi raw material.
　調製工程Ｓ３１で調製したＭｎＢｉ合金にＺｎを配合する。ＭｎＢｉ合金及びＺｎは、ショット、チップ、粉末、又はインゴット等、各種形態のいずれであってもよい。そして、ＭｎＢｉ合金とＺｎとを溶解する溶解工程Ｓ３２を行う。このように、主成分としてＭｎＢｉを含み、副成分としてＺｎ等を含む合金を、本明細書ではＭｎＢｉＺｎ合金という。溶解工程Ｓ３２では、蒸発したＺｎの一部が飛散してしまうことから、目標とするＭｎＢｉ系磁性粉末のＺｎ含有量よりも、Ｚｎを多めに配合することが好ましい。例えば、ＭｎＢｉ合金に対して、Ｚｎを１～１０質量％配合する。 Zn is mixed with the MnBi alloy prepared in the preparation step S31. The MnBi alloy and Zn may be in any of various forms such as shot, chip, powder, or ingot. And melt | dissolution process S32 which melt | dissolves a MnBi alloy and Zn is performed. In this specification, an alloy containing MnBi as a main component and Zn or the like as a subcomponent is referred to as an MnBiZn alloy in this specification. In the melting step S32, since a part of the evaporated Zn is scattered, it is preferable to add more Zn than the target Zn content of the MnBi-based magnetic powder. For example, 1 to 10% by mass of Zn is added to the MnBi alloy.
　次いで、溶融急冷法によってＭｎＢｉＺｎ合金の溶解物を急冷する液体急冷工程Ｓ３３と、粗粉砕工程Ｓ３４とを行う。粗粉砕工程Ｓ３４では公知の方法によって、急冷薄帯を粗粉砕して、ＭｎＢｉ系合金粉末を得る。このＭｎＢｉ系合金粉末は、主成分としてＭｎＢｉを含み、副成分としてＺｎ等を含む非磁性の粉末である。粉砕工程Ｓ３４の後に、磁場中熱処理工程Ｓ６、粉砕工程Ｓ７を行って、ＭｎＢｉ系磁性粉末（磁石粉末）を得ることができる。磁場中熱処理工程Ｓ６、及び、粉砕工程Ｓ７は、図３に示すフローチャートと同様にして行うことができる。この場合もこのような手順に限定されず、例えば、熱処理工程Ｓ５で十分に六方晶ＭｎＢｉ磁性相を生成した後、磁場中熱処理工程Ｓ６を行うことなく、粉砕工程Ｓ７において粒子を単磁区サイズにまで粉砕して、異方性の磁石粉末を得てもよい。 Next, a liquid quenching step S33 for quenching the melted MnBiZn alloy by a melt quenching method and a coarse pulverizing step S34 are performed. In the coarse pulverization step S34, the quenched ribbon is roughly pulverized by a known method to obtain MnBi-based alloy powder. This MnBi-based alloy powder is a nonmagnetic powder containing MnBi as a main component and Zn or the like as a subcomponent. After the pulverization step S34, a heat treatment step S6 in a magnetic field and a pulverization step S7 can be performed to obtain an MnBi-based magnetic powder (magnet powder). The heat treatment step S6 in the magnetic field and the pulverization step S7 can be performed in the same manner as the flowchart shown in FIG. In this case, the procedure is not limited to this. For example, after the hexagonal MnBi magnetic phase is sufficiently generated in the heat treatment step S5, the particles are made into a single domain size in the pulverization step S7 without performing the heat treatment step S6 in the magnetic field. To obtain an anisotropic magnet powder.
　続いて、図３に示すフローチャートと同様にして磁場中成形工程Ｓ８及び熱処理工程Ｓ９を行って、ＭｎＢｉ系金属磁石を製造することができる。また、図３に示すフローチャートと同様にして、ＭｎＢｉ系磁性粉末を用いて、成形工程Ｓ２０及び磁場中焼結工程Ｓ２１を行って、ＭｎＢｉ系金属磁石を製造してもよい。また、図３に示すフローチャートと同様にして、ＭｎＢｉ系磁性粉末と樹脂バインダとを用いて混練工程Ｓ１０、及び成形工程Ｓ１１を行って、ボンド磁石を製造してもよい。 Subsequently, the MnBi-based metal magnet can be manufactured by performing the forming step S8 in the magnetic field and the heat treatment step S9 in the same manner as the flowchart shown in FIG. Similarly to the flowchart shown in FIG. 3, the MnBi-based metal magnet may be manufactured by performing the molding step S20 and the magnetic field sintering step S21 using the MnBi-based magnetic powder. Similarly to the flowchart shown in FIG. 3, the bonded magnet may be manufactured by performing the kneading step S10 and the forming step S11 using the MnBi-based magnetic powder and the resin binder.
　この製造方法によって得られるＭｎＢｉ系磁性粉末における六方晶ＭｎＢｉ磁性相は、高い耐酸化性を有する。このため、ＭｎＢｉ系磁性粉末は、高温高湿環境下に長期間保管しても飽和磁化の低下を少なくすることができる。 The hexagonal MnBi magnetic phase in the MnBi magnetic powder obtained by this production method has high oxidation resistance. For this reason, the MnBi-based magnetic powder can reduce the decrease in saturation magnetization even when stored for a long time in a high temperature and high humidity environment.
　図５は、ＭｎＢｉ系磁性粉末の製造方法、及びこの製造方法によって得られるＭｎＢｉ系磁性粉末を用いたボンド磁石用コンパウンド、ボンド磁石、及び金属磁石の製造方法のさらに別の具体例を示すフローチャートである。 FIG. 5 is a flowchart showing still another specific example of a method for producing a MnBi-based magnetic powder and a method for producing a compound for a bonded magnet, a bonded magnet, and a metal magnet using the MnBi-based magnetic powder obtained by this manufacturing method. is there.
　この具体例では、図４に示すフローチャートと同様に、調製工程Ｓ３１、溶解工程Ｓ３２、及び液体急冷工程Ｓ３３を行った後に、熱処理工程Ｓ３４を行う。熱処理工程Ｓ３４では、液体急冷後の急冷薄帯を、不活性ガス雰囲気中において、２８０～３８０℃（好ましくは３００～３７０℃）で、３０～２００分間加熱する。熱処理工程Ｓ３４は、例えば１０Ｐａ以下の減圧下にある不活性ガス雰囲気中、又は真空中で行ってもよい。このような加熱条件でＭｎＢｉＺｎ合金に熱処理を施すことによって、Ｚｎが六方晶ＭｎＢｉ相の内部に拡散する。このようにして、Ｚｎを所定量含有する六方晶ＭｎＢｉ磁性相を有するＭｎＢｉ系合金が得られる。粉砕工程Ｓ３５によってＭｎＢｉ系合金を粉砕することにより、ＭｎＢｉ系磁性粉末を得ることができる。ここで、粉砕を例えばボールミル等を用いて、各粉末を、単磁区レベルとなる１０μｍ（単結晶のサイズ）程度になるまで粉砕する。この程度まで粉砕すれば、磁場を印加することなく、異方性のＭｎＢｉ系磁石粉末を得ることができる。 In this specific example, the heat treatment step S34 is performed after the preparation step S31, the dissolution step S32, and the liquid quenching step S33, as in the flowchart shown in FIG. In the heat treatment step S34, the quenched ribbon after liquid quenching is heated at 280 to 380 ° C. (preferably 300 to 370 ° C.) for 30 to 200 minutes in an inert gas atmosphere. The heat treatment step S34 may be performed, for example, in an inert gas atmosphere under a reduced pressure of 10 Pa or less, or in a vacuum. By subjecting the MnBiZn alloy to heat treatment under such heating conditions, Zn diffuses into the hexagonal MnBi phase. In this way, an MnBi-based alloy having a hexagonal MnBi magnetic phase containing a predetermined amount of Zn is obtained. By crushing the MnBi alloy in the crushing step S35, the MnBi magnetic powder can be obtained. Here, each powder is pulverized using a ball mill or the like until it reaches a single magnetic domain level of about 10 μm (single crystal size). If pulverized to this extent, anisotropic MnBi magnet powder can be obtained without applying a magnetic field.
　粉砕工程Ｓ３５で得られたＭｎＢｉ系磁性粉末を用いて、磁場中成形工程Ｓ８、及び熱処理工程Ｓ９を行うことによって、ＭｎＢｉ系金属磁石を得ることができる。図４に示すフローチャートと同様にして、磁場中成形工程Ｓ８又は混練工程Ｓ１０以降の工程を行って、ＭｎＢｉ系金属磁石及びボンド磁石を製造することができる。 By using the MnBi magnetic powder obtained in the pulverization step S35, the MnBi metal magnet can be obtained by performing the forming step S8 in the magnetic field and the heat treatment step S9. Similar to the flowchart shown in FIG. 4, the MnBi-based metal magnet and the bonded magnet can be manufactured by performing the steps in the magnetic field forming step S8 or the kneading step S10 and the subsequent steps.
　図６は、ＭｎＢｉ系金属磁石５０の斜視図である。ＭｎＢｉ系金属磁石の形状は、図６に示すような円柱形状に限定されるものではなく、例えば角柱形状であってもよいし、球形状であってもよい。ボンド磁石も、図６に示すような円柱形状であってもよいし、角柱形状又は球形状であってもよい。 FIG. 6 is a perspective view of the MnBi-based metal magnet 50. The shape of the MnBi-based metal magnet is not limited to the cylindrical shape as shown in FIG. 6, and may be, for example, a prismatic shape or a spherical shape. The bonded magnet may also have a cylindrical shape as shown in FIG. 6, a prismatic shape, or a spherical shape.
　ＭｎＢｉ系金属磁石５０の組成は、Ｚｎを含有する六方晶ＭｎＢｉ磁性相を含有する。六方晶ＭｎＢｉ磁性相における、Ｍｎ、Ｂｉ及びＺｎの合計に対するＺｎの含有量は０．５～８質量％である。この含有量は、高い磁気特性を維持しつつ耐食性を向上する観点から、例えば、０．３～５質量％であってもよく、０．４～４質量％であってもよい。 The composition of the MnBi-based metal magnet 50 includes a hexagonal MnBi magnetic phase containing Zn. The content of Zn in the hexagonal MnBi magnetic phase is 0.5 to 8% by mass with respect to the total of Mn, Bi and Zn. This content may be, for example, 0.3 to 5% by mass or 0.4 to 4% by mass from the viewpoint of improving corrosion resistance while maintaining high magnetic properties.
　ＭｎＢｉ系金属磁石５０の六方晶ＭｎＢｉ磁性相におけるＭｎ、Ｂｉ及びＺｎの含有量は、ＭｎＢｉ系磁性粉末の実施形態で説明した内容と同じであってもよい。ＭｎＢｉ系金属磁石５０は、上述のＭｎＢｉ系磁性粉末を加圧成形して作製した成形体を、熱処理又は焼結して得ることができる。 The contents of Mn, Bi and Zn in the hexagonal MnBi magnetic phase of the MnBi-based metal magnet 50 may be the same as those described in the embodiment of the MnBi-based magnetic powder. The MnBi-based metal magnet 50 can be obtained by heat-treating or sintering a molded body produced by pressure-molding the above-described MnBi-based magnetic powder.
　ボンド磁石用コンパウンドは、一実施形態において、上述のＭｎＢｉ系磁性粉末と樹脂バインダとの混練物で構成される。ボンド磁石は、このようなボンド磁石用コンパウンドを成形して得られる。ボンド磁石は、上述の実施形態に係るＭｎＢｉ系磁性粉末と樹脂バインダとを含む。ボンド磁石用コンパウンド及びボンド磁石に含まれるＭｎＢｉ系磁性粉末の組成は、上述の実施形態で説明した内容と同じであってもよい。 In one embodiment, the compound for bond magnet is composed of a kneaded product of the above-described MnBi-based magnetic powder and a resin binder. The bonded magnet is obtained by molding such a bonded magnet compound. The bonded magnet includes the MnBi-based magnetic powder and the resin binder according to the above-described embodiment. The composition of the bonded magnet compound and the MnBi-based magnetic powder contained in the bonded magnet may be the same as described in the above embodiment.
　以上、本発明の幾つかの実施形態を説明したが、本発明が上述の幾つかの実施形態に限定されないことはいうまでもない。 As mentioned above, although some embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to the above-mentioned some embodiment.
　以下に、実施例と比較例を挙げて、本発明の内容をより詳細に説明する。ただし、本発明は、下記の実施例に限定されるものではない。 Hereinafter, the contents of the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to the following examples.
(実施例１)
＜磁石粉末の作製＞
　Ｍｎチップ及びＢｉショットを、アーク溶融炉で溶解して、ＭｎＢｉ合金を調製した。ＭｎＢｉ合金におけるＭｎとＢｉのモル比は、Ｍｎ：Ｂｉ＝４５：５５とした。アーク溶融炉で得られたＭｎＢｉ合金を、底部にφ０．４５ｍｍのオリフィス径を有する透明石英管の出湯ノズルに５ｇ入れた。液体急冷装置のチャンバー内を真空引きした後、５０ｋＰａのアルゴンガス雰囲気中にて高周波溶解によって、出湯ノズル内のＭｎＢｉ合金を溶解した。そして、溶湯噴射圧１０ｋＰａにて銅製のロール上にＭｎＢｉ溶湯を噴射して急冷薄帯を得た。ロールの回転速度は２０ｍ／ｓ、ロールと出湯ノズルの距離は０．４ｍｍとした。得られた急冷薄帯を粉砕して、粒径が１５０μｍ以下のＭｎＢｉ合金粉末を得た。 (Example 1)
<Production of magnet powder>
The Mn chip and Bi shot were melted in an arc melting furnace to prepare a MnBi alloy. The molar ratio of Mn to Bi in the MnBi alloy was Mn: Bi = 45: 55. 5 g of the MnBi alloy obtained in the arc melting furnace was put into a hot water discharge nozzle of a transparent quartz tube having an orifice diameter of φ0.45 mm at the bottom. After evacuating the chamber of the liquid quenching apparatus, the MnBi alloy in the hot water nozzle was melted by high frequency melting in an argon gas atmosphere of 50 kPa. Then, a MnBi molten metal was sprayed onto a copper roll at a molten metal injection pressure of 10 kPa to obtain a quenched ribbon. The rotational speed of the roll was 20 m / s, and the distance between the roll and the hot water nozzle was 0.4 mm. The obtained quenched ribbon was pulverized to obtain a MnBi alloy powder having a particle size of 150 μm or less.
　ＭｎＢｉ合金粉末（１００質量％）にＺｎ粉末（３．０質量％）を混合して混合粉末を調製した。１０Ｐａ以下の不活性ガス（窒素ガス）雰囲気中、温度３２０℃、時間１２０分間の条件で、混合粉末の熱処理を行って、ＭｎＢｉにＺｎを拡散させた。このときの温度を、表１に「熱処理温度」として示した。このようにして、ＭｎＢｉ系磁性粉末を得た。その後、所定の加熱条件下（雰囲気：アルゴンガス、温度：３００℃、時間：２４０分間）、ＭｎＢｉ系磁性粉末に０．６Ｔ（６０００Ｇ）の磁場を印加する磁場中熱処理を施して、磁石粉末を得た。 A mixed powder was prepared by mixing Zn powder (3.0% by mass) with MnBi alloy powder (100% by mass). The mixed powder was heat-treated in an inert gas (nitrogen gas) atmosphere of 10 Pa or less at a temperature of 320 ° C. for 120 minutes to diffuse Zn into MnBi. The temperature at this time is shown as “heat treatment temperature” in Table 1. In this way, an MnBi magnetic powder was obtained. After that, under predetermined heating conditions (atmosphere: argon gas, temperature: 300 ° C., time: 240 minutes), MnBi magnetic powder is subjected to heat treatment in a magnetic field in which a magnetic field of 0.6 T (6000 G) is applied, and the magnet powder is obtained. Obtained.
＜評価１＞
　ＩＣＰ発光分光分析装置（サーモフィッシャーサイエンティフィック株式会社製，装置名：ｉＣＡＰ６０００）を用いて、磁石粉末におけるＺｎ含有量を測定した。このＺｎ含有量は、磁石粉末全体に対するＺｎ含有量である。表１に、「Ｚｎ含有量（１）」として測定結果を示す。 <Evaluation 1>
The Zn content in the magnet powder was measured using an ICP emission spectroscopic analyzer (Thermo Fisher Scientific Co., Ltd., apparatus name: iCAP6000). This Zn content is the Zn content with respect to the entire magnet powder. Table 1 shows the measurement results as “Zn content (1)”.
　ＦＥ－ＳＥＭ（ＪＥＯＬ製，装置名：ＪＳＭ－７８００Ｆ）を用いて、磁石粉末を５００倍に拡大して観察した。この観察画像において、磁石粉末に含まれる六方晶ＭｎＢｉ磁性相、Ｂｉ相及びＭｎ相を特定した。ＦＥ－ＳＥＭ付随のＥＤＸを用いて、六方晶ＭｎＢｉ磁性相におけるＺｎ含有量を測定した。Ｚｎ含有量の測定は、任意に選択した５つの六方晶ＭｎＢｉ磁性相において行った。Ｚｎ含有量の測定値の平均値を、「Ｚｎ含有量（２）」として表１に示す。 Using a FE-SEM (manufactured by JEOL, apparatus name: JSM-7800F), the magnet powder was observed at a magnification of 500 times. In this observation image, the hexagonal MnBi magnetic phase, Bi phase and Mn phase contained in the magnet powder were specified. Zn content in the hexagonal MnBi magnetic phase was measured using EDX accompanied with FE-SEM. The Zn content was measured in five arbitrarily selected hexagonal MnBi magnetic phases. The average value of the measured Zn content is shown in Table 1 as “Zn content (2)”.
　振動試料型磁束計（ＶＳＭ：東英工業製ＶＳＭ－５型）を用いて、磁石粉末の飽和磁化（４πＩｍａｘ）、残留磁束密度（Ｂｒ）、及び保磁力（Ｈｃｊ）を測定した。測定結果は、表２の「保管前」の欄に示すとおりであった。 Using a vibrating sample magnetometer (VSM: VSM-5 manufactured by Toei Kogyo Co., Ltd.), the saturation magnetization (4πI max ), residual magnetic flux density (Br), and coercive force (Hcj) of the magnet powder were measured. The measurement results were as shown in the column “Before Storage” in Table 2.
＜評価２＞
　調製した磁石粉末を、温度４０℃、相対湿度５０％の空気中で４日間保管した。保管後の磁気特性を、「評価１」と同様にして測定した。さらに、不活性ガス融解－非分散型赤外線吸収法（ＨＯＲＩＢＡ製：装置名：ＥＭＧＡ－９３０）によって、保管後の磁石粉末の酸素含有量を測定した。これらの測定結果は、表２の「保管後」の欄に示すとおりであった。 <Evaluation 2>
The prepared magnet powder was stored in air at a temperature of 40 ° C. and a relative humidity of 50% for 4 days. The magnetic properties after storage were measured in the same manner as in “Evaluation 1”. Further, the oxygen content of the magnet powder after storage was measured by an inert gas melting-non-dispersive infrared absorption method (manufactured by HORIBA: apparatus name: EMGA-930). These measurement results were as shown in the column “After Storage” in Table 2.
（実施例２)
　ＭｎＢｉ合金粉末（１００質量％）にＺｎ粉末（５．０質量％）を混合して混合粉末を調製したこと以外は、実施例１と同様にしてＭｎＢｉ系磁性粉末を調製して磁石粉末を得た。そして、実施例１と同様にして評価１，２を行った。評価結果は表１及び表２に示すとおりであった。 (Example 2)
A magnetic powder was obtained by preparing a MnBi magnetic powder in the same manner as in Example 1 except that a mixed powder was prepared by mixing a Zn powder (5.0% by mass) with an MnBi alloy powder (100% by mass). It was. Evaluations 1 and 2 were performed in the same manner as in Example 1. The evaluation results are as shown in Tables 1 and 2.
（実施例３)
　混合粉末の熱処理時の温度を３６０℃としたこと以外は、実施例１と同様にしてＭｎＢｉ系磁性粉末を調製して磁石粉末を得た。そして、実施例１と同様にして評価１，２を行った。評価結果は表１及び表２に示すとおりであった。 (Example 3)
A magnetic powder was obtained by preparing a MnBi magnetic powder in the same manner as in Example 1 except that the temperature during heat treatment of the mixed powder was 360 ° C. Evaluations 1 and 2 were performed in the same manner as in Example 1. The evaluation results are as shown in Tables 1 and 2.
　(実施例４)
　ＭｎＢｉ合金粉末（１００質量％）にＺｎ粉末（５．０質量％）を混合して混合粉末を調製したこと以外は、実施例３と同様にしてＭｎＢｉ系磁性粉末を調製して磁石粉末を得た。そして、実施例３と同様にして、磁石粉末の評価を行った。評価結果は表１及び表２に示すとおりであった。 Example 4
A magnetic powder was obtained by preparing a MnBi magnetic powder in the same manner as in Example 3 except that a mixed powder was prepared by mixing a Zn powder (5.0 mass%) with an MnBi alloy powder (100 mass%). It was. The magnet powder was evaluated in the same manner as in Example 3. The evaluation results are as shown in Tables 1 and 2.
（実施例５)
　ＭｎＢｉ合金におけるＭｎとＢｉのモル比は、Ｍｎ：Ｂｉ＝３７．５：６２．５とした以外は、実施例１と同様にしてＭｎＢｉ系磁性粉末を調製して磁石粉末を得た。そして、実施例１と同様にして評価１，２を行った。評価結果は表１及び表２に示すとおりであった。 (Example 5)
A magnetic powder was obtained by preparing a MnBi magnetic powder in the same manner as in Example 1 except that the molar ratio of Mn to Bi in the MnBi alloy was Mn: Bi = 37.5: 62.5. Evaluations 1 and 2 were performed in the same manner as in Example 1. The evaluation results are as shown in Tables 1 and 2.
（実施例６）
　Ｍｎチップ及びＢｉショットを、アーク溶融炉で溶解して、ＭｎＢｉ合金を調製した。ＭｎＢｉ合金におけるＭｎとＢｉのモル比は、Ｍｎ：Ｂｉ＝３７．５：６２．５とした。アーク溶融炉で得られたＭｎＢｉ合金（１００質量％）に対してＺｎを１質量％添加し、再度アーク溶解炉で溶解した。得られたＭｎＢｉＺｎ合金を、底部にφ０．４５ｍｍのオリフィス径を有する透明石英管の出湯ノズルに５ｇ入れた。液体急冷装置のチャンバー内を真空引きした後、５０ｋＰａのアルゴンガス雰囲気中にて高周波溶解によって、出湯ノズル内のＭｎＢｉＺｎ合金を溶解した。そして、溶湯噴射圧１０ｋＰａにて銅製のロール上にＭｎＢｉＺｎ溶湯を噴射して急冷薄帯を得た。ロールの回転速度は２０ｍ／ｓ、ロールと出湯ノズルの距離は０．４ｍｍとした。得られた急冷薄帯を粗粉砕して、粒径が１５０μｍ以下であるＭｎＢｉ系合金粉末を得た。 (Example 6)
The Mn chip and Bi shot were melted in an arc melting furnace to prepare a MnBi alloy. The molar ratio of Mn to Bi in the MnBi alloy was Mn: Bi = 37.5: 62.5. 1% by mass of Zn was added to the MnBi alloy (100% by mass) obtained in the arc melting furnace, and again melted in the arc melting furnace. 5 g of the obtained MnBiZn alloy was put into a hot water nozzle of a transparent quartz tube having an orifice diameter of φ0.45 mm at the bottom. After evacuating the chamber of the liquid quenching apparatus, the MnBiZn alloy in the hot water nozzle was melted by high-frequency melting in an argon gas atmosphere of 50 kPa. Then, a MnBiZn molten metal was sprayed onto a copper roll at a molten metal injection pressure of 10 kPa to obtain a quenched ribbon. The rotational speed of the roll was 20 m / s, and the distance between the roll and the hot water nozzle was 0.4 mm. The obtained quenched ribbon was coarsely pulverized to obtain a MnBi alloy powder having a particle size of 150 μm or less.
　所定の加熱条件下（雰囲気：アルゴンガス、温度：３００℃、時間：２４０分間）、ＭｎＢｉ系合金粉末に０．６Ｔ（６０００Ｇ）の磁場を印加する磁場中熱処理を施して、ＭｎＢｉ系磁性粉末（磁石粉末）を得た。表１には、このときの磁場中熱処理の温度を示す。そして、実施例１と同様にして評価１，２を行った。評価結果は表１及び表２に示すとおりであった。 Under predetermined heating conditions (atmosphere: argon gas, temperature: 300 ° C., time: 240 minutes), MnBi-based alloy powder is subjected to heat treatment in a magnetic field in which a magnetic field of 0.6 T (6000 G) is applied, and MnBi-based magnetic powder ( Magnet powder) was obtained. Table 1 shows the temperature of the heat treatment in the magnetic field at this time. Evaluations 1 and 2 were performed in the same manner as in Example 1. The evaluation results are as shown in Tables 1 and 2.
（実施例７）
　アーク溶融炉で得られたＭｎＢｉ合金（１００質量％）に対してＺｎを２質量％添加したこと以外は、実施例６と同様にしてＭｎＢｉ系合金粉末を調製して磁石粉末を得た。そして、実施例１と同様にして評価１，２を行った。評価結果は表１及び表２に示すとおりであった。 (Example 7)
A MnBi-based alloy powder was prepared in the same manner as in Example 6 except that 2% by mass of Zn was added to the MnBi alloy (100% by mass) obtained in the arc melting furnace to obtain a magnet powder. Evaluations 1 and 2 were performed in the same manner as in Example 1. The evaluation results are as shown in Tables 1 and 2.
（実施例８）
　実施例６と同様にして、ロール上にＭｎＢｉＺｎ溶湯を噴射して急冷薄帯を得た。この急冷薄帯の熱処理（雰囲気：アルゴンガス、温度：３００℃、時間：２４０分間）を行った。この熱処理は、１０Ｐａ以下の不活性ガス雰囲気中で行った。表１には、このときの熱処理の温度を示す。ボールミル（条件：５０ｒｐｍ、２時間）を用いて急冷薄帯を粒径が６３μｍ以下になるまで粉砕して、ＭｎＢｉ系磁性粉末（磁石粉末）を得た。磁石粉末の平均粒径は１５μｍであった。そして、実施例１と同様にして評価１，２を行った。評価結果は表１及び表２に示すとおりであった。 (Example 8)
In the same manner as in Example 6, a MnBiZn molten metal was sprayed onto the roll to obtain a quenched ribbon. The quenched ribbon was heat treated (atmosphere: argon gas, temperature: 300 ° C., time: 240 minutes). This heat treatment was performed in an inert gas atmosphere of 10 Pa or less. Table 1 shows the temperature of the heat treatment at this time. The quenched ribbon was pulverized using a ball mill (conditions: 50 rpm, 2 hours) until the particle size became 63 μm or less to obtain MnBi-based magnetic powder (magnet powder). The average particle size of the magnet powder was 15 μm. Evaluations 1 and 2 were performed in the same manner as in Example 1. The evaluation results are as shown in Tables 1 and 2.
（比較例１)
　Ｚｎ粉末を混合しなかったこと以外は、実施例１と同様にしてＭｎＢｉ磁性粉末を調製して磁石粉末を得た。そして、実施例１と同様にして評価１，２を行った。評価結果は表１及び表２に示すとおりであった。 (Comparative Example 1)
A magnetic powder was obtained by preparing a MnBi magnetic powder in the same manner as in Example 1 except that the Zn powder was not mixed. Evaluations 1 and 2 were performed in the same manner as in Example 1. The evaluation results are as shown in Tables 1 and 2.
（比較例２)
　ＭｎＢｉ合金粉末（１００質量％）にＺｎ粉末（８．０質量％）を混合して混合粉末を調製したこと以外は、実施例１と同様にしてＭｎＢｉ系磁性粉末を調製して磁石粉末を得た。そして、実施例１と同様にして評価１，２を行った。評価結果は表１及び表２に示すとおりであった。 (Comparative Example 2)
A magnetic powder was obtained by preparing a MnBi magnetic powder in the same manner as in Example 1 except that a mixed powder was prepared by mixing a Zn powder (8.0% by mass) with MnBi alloy powder (100% by mass). It was. Evaluations 1 and 2 were performed in the same manner as in Example 1. The evaluation results are as shown in Tables 1 and 2.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表２には、温度４０℃、相対湿度５０％の空気中で４日間保管する前と保管後の飽和磁化の値から、以下の式によって算出した飽和磁化劣化率を示した。
　　飽和磁化劣化率（％）＝100－［保管後の飽和磁化］／［保管前の飽和磁化］×100 Table 2 shows the saturation magnetization deterioration rate calculated by the following equation from the values of saturation magnetization before and after storage for 4 days in air at a temperature of 40 ° C. and a relative humidity of 50%.
Saturation magnetization deterioration rate (%) = 100− [saturation magnetization after storage] / [saturation magnetization before storage] × 100
　表１に示すとおり、各実施例の磁石粉末のＺｎ含有量（２）は、０．５～８質量％の範囲内であった。表２に示すとおり、各実施例の磁石粉末は、温度４０℃、相対湿度５０％の空気中で４日間保管した後でも飽和磁化の劣化率は５％以下であった。また、酸素含有量は３０００ｐｐｍ以下であった。このことから、各実施例の磁石粉末は、六方晶ＭｎＢｉ磁性相に所定量のＺｎを含有することによって、酸化劣化が抑制され、飽和磁化の劣化率を小さくできることが確認された。一方、比較例１では、六方晶ＭｎＢｉ磁性相がＺｎを含有しないことから、酸化劣化が進行して飽和磁化の劣化率が大きくなることが確認された。比較例１の磁石粉末の酸素含有量は実施例よりも高かった。 As shown in Table 1, the Zn content (2) of the magnet powder of each example was in the range of 0.5 to 8% by mass. As shown in Table 2, the magnet powder of each example had a saturation magnetization deterioration rate of 5% or less even after being stored in air at a temperature of 40 ° C. and a relative humidity of 50% for 4 days. Moreover, oxygen content was 3000 ppm or less. From this, it was confirmed that the magnet powders of the respective examples contain a predetermined amount of Zn in the hexagonal MnBi magnetic phase, thereby suppressing oxidative deterioration and reducing the deterioration rate of saturation magnetization. On the other hand, in Comparative Example 1, since the hexagonal MnBi magnetic phase did not contain Zn, it was confirmed that the deterioration rate of saturation magnetization increased due to the progress of oxidation deterioration. The oxygen content of the magnet powder of Comparative Example 1 was higher than that of the example.
　比較例２では、Ｚｎの含有量（２）が多いため酸化劣化が抑制されていた。しかしながら、非磁性成分の含有量が大きくなっているため、飽和磁化の値が低かった。 In Comparative Example 2, since the Zn content (2) is large, oxidative degradation was suppressed. However, since the content of the nonmagnetic component is large, the value of the saturation magnetization is low.
＜評価３＞
　実施例１，６，７，８及び比較例１で調製した磁石粉末を、空気中、温度１００℃で１時間保管した（条件（１））。また、実施例１，６，７，８及び比較例１で調製した磁石粉末を、空気中、温度２５０℃で１時間保管した（条件（２））。条件（１）又は条件（２）で保管した後の磁石粉末の磁気特性を、「評価１」と同様にしてそれぞれ測定した。さらに、表２と同様にして、飽和磁化劣化率を算出した。条件（１）で保管したときの結果を表３に、条件（２）で保管したときの結果を表４にそれぞれ示す。 <Evaluation 3>
The magnet powders prepared in Examples 1, 6, 7, 8 and Comparative Example 1 were stored in air at a temperature of 100 ° C. for 1 hour (condition (1)). Further, the magnet powders prepared in Examples 1, 6, 7, 8 and Comparative Example 1 were stored in air at a temperature of 250 ° C. for 1 hour (condition (2)). The magnetic properties of the magnet powder after being stored under condition (1) or condition (2) were measured in the same manner as in “Evaluation 1”. Further, the saturation magnetization deterioration rate was calculated in the same manner as in Table 2. Table 3 shows the results when stored under condition (1), and Table 4 shows the results when stored under condition (2).
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　表３に示すとおり、条件（１）で保管したときの実施例１，６，７，８の飽和磁化の劣化率は１５％以下であり、比較例１よりも飽和磁化の劣化率が大幅に小さくなっていた。表４に示すとおり、条件（２）で保管したときの実施例１，６，７，８の飽和磁化の劣化率は２０％以下であり、比較例１よりも飽和磁化の劣化率が大幅に小さくなっていた。 As shown in Table 3, the saturation magnetization deterioration rate of Examples 1, 6, 7, and 8 when stored under condition (1) is 15% or less, and the saturation magnetization deterioration rate is significantly higher than that of Comparative Example 1. It was getting smaller. As shown in Table 4, the deterioration rate of saturation magnetization of Examples 1, 6, 7, and 8 when stored under the condition (2) is 20% or less, and the deterioration rate of saturation magnetization is significantly higher than that of Comparative Example 1. It was getting smaller.
（実施例９，比較例３～１２）
　ＺｎとＺｎ以外の元素を添加した場合のＭｎＢｉ系磁性粉末の耐酸化特性の比較を行った。ＭｎＢｉ合金に添加する元素を表５のとおりにしたこと以外は、実施例６と同様にして磁石粉末を得た。比較のため、添加元素を含まないＭｎＢｉ合金粉末を、実施例６と同じ条件で熱処理して磁石粉末を調製した（比較例３）。 (Example 9, Comparative Examples 3 to 12)
The oxidation resistance characteristics of MnBi-based magnetic powders when Zn and other elements than Zn were added were compared. Magnet powder was obtained in the same manner as in Example 6 except that the elements added to the MnBi alloy were as shown in Table 5. For comparison, a magnetic powder was prepared by heat-treating MnBi alloy powder containing no additive element under the same conditions as in Example 6 (Comparative Example 3).
　調製した磁石粉末を、大気中、常温（約２０℃）で保管した。保管前及び保管後（４日間後及び１５日間後）の飽和磁化（４πＩｍａｘ）、残留磁束密度（Ｂｒ）、及び保磁力（Ｈｃｊ）を、振動試料型磁束計（ＶＳＭ：東英工業製ＶＳＭ－５型）を用いて測定した。測定結果を表５に示す。 The prepared magnet powder was stored at normal temperature (about 20 ° C.) in the air. The saturation sample (4πI max ), residual magnetic flux density (Br), and coercive force (Hcj) before storage and after storage (after 4 days and 15 days) were measured using a vibrating sample magnetometer (VSM: VSM manufactured by Toei Industry Co., Ltd.). -5 type). Table 5 shows the measurement results.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
　表５に示すとおり、Ｚｎを添加した実施例９の磁石粉末は、１５日間保管後においても高い飽和磁化を有していた。すなわち、Ｚｎを用いることによって、酸化が十分に抑制されて、高い飽和磁化を維持できることが確認された。なお、比較例９～１２は、初期（保管前）の飽和磁化が低すぎたため、保管後の評価を行わなかった。 As shown in Table 5, the magnet powder of Example 9 to which Zn was added had high saturation magnetization even after storage for 15 days. That is, it was confirmed that by using Zn, oxidation is sufficiently suppressed and high saturation magnetization can be maintained. In Comparative Examples 9 to 12, since the saturation magnetization at the initial stage (before storage) was too low, evaluation after storage was not performed.
　本発明によれば、高温高湿環境下に長期間保管しても、高い飽和磁化を維持できるＭｎＢｉ系磁性粉末、及びそのようなＭｎＢｉ系磁性粉末を製造する方法を提供することができる。また、本発明は、高温高湿環境下に長期間保管しても、高い飽和磁化を維持できるボンド磁石、そのようなボンド磁石を製造することが可能なボンド磁石用コンパウンド、及び、金属磁石を提供することができる。 According to the present invention, it is possible to provide a MnBi-based magnetic powder capable of maintaining high saturation magnetization even when stored in a high-temperature and high-humidity environment for a long period of time, and a method for producing such MnBi-based magnetic powder. The present invention also provides a bonded magnet that can maintain high saturation magnetization even when stored in a high temperature and high humidity environment for a long period of time, a compound for bonded magnet that can produce such a bonded magnet, and a metal magnet. Can be provided.
　１０…六方晶ＭｎＢｉ磁性相、２０…Ｂｉ相、３０…樹脂、５０…ＭｎＢｉ系金属磁石。 10 ... hexagonal MnBi magnetic phase, 20 ... Bi phase, 30 ... resin, 50 ... MnBi-based metal magnet.

Claims (7)

  1. 　六方晶ＭｎＢｉ磁性相を含有し、前記六方晶ＭｎＢｉ磁性相におけるＺｎの含有量が０．５～８質量％であるＭｎＢｉ系磁性粉末。 An MnBi-based magnetic powder containing a hexagonal MnBi magnetic phase and having a Zn content of 0.5 to 8% by mass in the hexagonal MnBi magnetic phase.
  2. 　ＭｎＢｉ合金粉末とＺｎ粉末とを混合し、真空中、又は減圧下にある不活性ガス雰囲気中において２８０～３８０℃で熱処理して、Ｚｎを含む六方晶ＭｎＢｉ磁性相を含有するＭｎＢｉ系磁性粉末を得る工程を有し、
    　前記六方晶ＭｎＢｉ磁性相におけるＺｎの含有量が０．５～８質量％である、ＭｎＢｉ系磁性粉末の製造方法。     MnBi alloy powder and Zn powder are mixed and heat-treated at 280 to 380 ° C. in an inert gas atmosphere under vacuum or reduced pressure to obtain a MnBi magnetic powder containing a hexagonal MnBi magnetic phase containing Zn. Having a process of obtaining
    A method for producing a MnBi-based magnetic powder, wherein the content of Zn in the hexagonal MnBi magnetic phase is 0.5 to 8% by mass.
  3. 　ＭｎＢｉＺｎ合金を溶融急冷して得られた急冷薄帯の熱処理及び粉砕を行って、Ｚｎを含む六方晶ＭｎＢｉ磁性相を含有するＭｎＢｉ系磁性粉末を得る工程を有し、
    　前記六方晶ＭｎＢｉ磁性相におけるＺｎの含有量が０．５～８質量％である、ＭｎＢｉ系磁性粉末の製造方法。     A step of obtaining a MnBi-based magnetic powder containing a hexagonal MnBi magnetic phase containing Zn by performing heat treatment and pulverization of a quenched ribbon obtained by melting and quenching a MnBiZn alloy;
    A method for producing a MnBi-based magnetic powder, wherein the content of Zn in the hexagonal MnBi magnetic phase is 0.5 to 8% by mass.
  4. 　前記熱処理は、不活性ガス雰囲気中において２８０～３８０℃で行う、請求項３に記載のＭｎＢｉ系磁性粉末の製造方法。 The method for producing an MnBi-based magnetic powder according to claim 3, wherein the heat treatment is performed at 280 to 380 ° C in an inert gas atmosphere.
  5. 　請求項１に記載のＭｎＢｉ系磁性粉末と樹脂バインダとを含む混練物からなるボンド磁石用コンパウンド。 A compound for a bonded magnet comprising a kneaded material containing the MnBi magnetic powder according to claim 1 and a resin binder.
  6. 　請求項１に記載のＭｎＢｉ系磁性粉末と樹脂バインダとを含むボンド磁石。 A bonded magnet comprising the MnBi magnetic powder according to claim 1 and a resin binder.
  7. 　Ｚｎを含有する六方晶ＭｎＢｉ磁性相を含有し、
    　前記六方晶ＭｎＢｉ磁性相における、Ｍｎ、Ｂｉ及びＺｎの合計に対するＺｎの含有量が０．５～８質量％である、金属磁石。     Containing a hexagonal MnBi magnetic phase containing Zn,
    A metal magnet having a Zn content of 0.5 to 8% by mass relative to the total of Mn, Bi and Zn in the hexagonal MnBi magnetic phase.
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