WO2013047467A1 - 希土類永久磁石及び希土類永久磁石の製造方法 - Google Patents

希土類永久磁石及び希土類永久磁石の製造方法 Download PDF

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Publication number
WO2013047467A1
WO2013047467A1 PCT/JP2012/074471 JP2012074471W WO2013047467A1 WO 2013047467 A1 WO2013047467 A1 WO 2013047467A1 JP 2012074471 W JP2012074471 W JP 2012074471W WO 2013047467 A1 WO2013047467 A1 WO 2013047467A1
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Prior art keywords
magnet
permanent magnet
rare earth
sintering
earth permanent
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English (en)
French (fr)
Japanese (ja)
Inventor
孝志 尾崎
克也 久米
利昭 奥野
出光 尾関
智弘 大牟礼
啓介 太白
山本　貴士
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Nitto Denko Corp
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Nitto Denko Corp
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Priority to CN201280047635.6A priority Critical patent/CN103843081A/zh
Priority to EP12836769.5A priority patent/EP2763147A4/en
Priority to KR1020147011139A priority patent/KR20140082741A/ko
Priority to IN1766CHN2014 priority patent/IN2014CN01766A/en
Priority to US14/241,511 priority patent/US20140241929A1/en
Publication of WO2013047467A1 publication Critical patent/WO2013047467A1/ja
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    • 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
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/0536—Alloys characterised by their composition containing rare earth metals sintered
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • 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
    • B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
    • B22F1/107—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material containing organic material comprising solvents, e.g. for slip casting
    • 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
    • B22F3/10—Sintering only
    • B22F3/1017—Multiple heating or additional steps
    • B22F3/1021—Removal of binder or filler
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/02—Making ferrous alloys by powder metallurgy
    • C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
    • C22C33/0278—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5%
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
    • 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
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0572—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes with a protective layer
    • 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
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
    • H01F1/0577—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered
    • 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
    • H01F41/0253—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 for manufacturing permanent magnets
    • H01F41/0266—Moulding; Pressing
    • 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
    • H01F41/0253—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 for manufacturing permanent magnets
    • H01F41/0293—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 for manufacturing permanent magnets diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets
    • 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
    • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C2202/00—Physical properties
    • C22C2202/02—Magnetic

Definitions

  • the present invention relates to a rare earth permanent magnet and a method for producing a rare earth permanent magnet.
  • Permanent magnet motors used in hybrid cars, hard disk drives, and the like have been required to be smaller, lighter, higher in output, and more efficient. Further, in order to realize a reduction in size and weight, an increase in output, and an increase in efficiency in the permanent magnet motor, further improvement in magnetic characteristics is required for the permanent magnet embedded in the permanent magnet motor.
  • Permanent magnets include ferrite magnets, Sm—Co magnets, Nd—Fe—B magnets, Sm 2 Fe 17 N x magnets, and Nd—Fe—B magnets with particularly high residual magnetic flux density. Used as a permanent magnet for a permanent magnet motor.
  • a powder sintering method is generally used as a manufacturing method of the permanent magnet.
  • the powder sintering method first, raw materials are roughly pulverized, and magnet powder is manufactured by finely pulverizing with a jet mill (dry pulverization) or a wet bead mill (wet pulverization). Thereafter, the magnet powder is put into a mold and press-molded into a desired shape while applying a magnetic field from the outside. Then, it is manufactured by sintering the solid magnet powder formed into a desired shape at a predetermined temperature (for example, 800 ° C. to 1150 ° C. for Nd—Fe—B magnets).
  • a predetermined temperature for example, 800 ° C. to 1150 ° C. for Nd—Fe—B magnets.
  • JP 3298219 A (pages 4 and 5)
  • the magnetic performance of the permanent magnet is basically improved if the crystal grain size of the sintered body is reduced because the magnetic properties of the magnet are derived by the single domain fine particle theory. .
  • wet bead mill pulverization which is one of the pulverization methods used when pulverizing magnet raw materials, is filled with beads (media) in a container and rotated, and a slurry in which the raw materials are mixed in a solvent is added.
  • This is a method of grinding and crushing raw materials.
  • wet bead milling even when wet bead milling is used, it is difficult to pulverize most of the magnet raw material to a fine particle size range (for example, 0.1 ⁇ m to 5.0 ⁇ m).
  • the present invention has been made in order to solve the problems in the prior art, and in the case of wet pulverizing the magnet raw material, the wet pulverization property of the wet pulverization can be improved by wet pulverization with a specific organometallic compound added.
  • An object of the present invention is to provide a rare earth permanent magnet and a method for producing a rare earth permanent magnet that can be improved, and as a result, can reduce the crystal grain size after sintering, and have improved magnetic performance.
  • the rare earth permanent magnet according to the present invention includes a magnet raw material and a general formula M- (OR) x (where M is Nd, Al, Cu, Ag, Dy, Tb, V, Mo, Zr, At least one of Ta, Ti, W, and Nb is included, R is a substituent composed of a hydrocarbon having a carbon chain length of 2 to 16, and may be linear or branched, and x is an arbitrary integer.
  • a magnet powder obtained by pulverizing the magnet raw material by wet pulverization in an organic solvent, and attaching the organometallic compound to the particle surface of the magnet powder It is manufactured by a step of producing a molded body by molding powder and a step of sintering the molded body.
  • the rare earth permanent magnet according to the present invention is characterized in that R in the general formula is an alkyl group.
  • the step of producing the molded body includes forming a slurry in which the magnet powder, the organic solvent, and a binder resin are mixed, and molding the slurry into a sheet shape. A green sheet is produced as the molded body.
  • the rare earth permanent magnet according to the present invention is removed by scattering the binder resin by holding the molded body at a binder resin decomposition temperature for a predetermined time in a non-oxidizing atmosphere before sintering the molded body. It is characterized by doing.
  • the molded body in the step of removing the binder resin by scattering, is kept at 200 ° C. to 900 ° C. for a certain time in a hydrogen atmosphere or a mixed gas atmosphere of hydrogen and an inert gas. It is characterized by holding.
  • the method for producing a rare earth permanent magnet according to the present invention includes a magnet raw material and a general formula M- (OR) x (where M is Nd, Al, Cu, Ag, Dy, Tb, V, Mo, Zr, Ta). , Ti, W, and Nb, and R is a substituent composed of hydrocarbon having a carbon chain length of 2 to 16, which may be linear or branched, and x is an arbitrary integer.)
  • the method for producing a rare earth permanent magnet according to the present invention is characterized in that R in the general formula is an alkyl group.
  • the step of producing the molded body includes generating a slurry in which the magnet powder, the organic solvent, and a binder resin are mixed, and molding the slurry into a sheet shape.
  • a green sheet is produced as the molded body.
  • the method for producing a rare earth permanent magnet according to the present invention before sintering the molded body, scatters the binder resin by holding the molded body at a binder resin decomposition temperature for a certain time in a non-oxidizing atmosphere. It is made to remove.
  • the molded body in the step of scattering and removing the binder resin, is 200 ° C. to 900 ° C. in a hydrogen atmosphere or a mixed gas atmosphere of hydrogen and an inert gas. And holding for a certain time.
  • wet pulverization is performed by wet pulverizing the magnet raw material and the organometallic compound in an organic solvent. It becomes possible to improve grindability. For example, most of the magnet raw material can be pulverized to a fine particle size range (for example, 0.1 ⁇ m to 5.0 ⁇ m). As a result, the crystal grain size after sintering can be reduced, and the magnetic performance can be improved.
  • the organometallic compound adheres to the particle surface of the magnet powder.
  • elements such as Nd, Al, Cu, Ag, Dy, Tb, V, Mo, Zr, Ta, Ti, W, Nb, etc.
  • the organometallic compound can be easily dissolved in a general-purpose solvent such as toluene, and the magnet powder can be appropriately attached to the particle surface.
  • the organometallic compound composed of an alkyl group is used as the organometallic compound added to the magnet powder, the organometallic compound can be easily thermally decomposed. Become. As a result, it is possible to more reliably reduce the amount of carbon in the molded body when calcining.
  • the permanent magnet is constituted by a magnet obtained by sintering a green sheet formed from a slurry in which magnet powder, a resin binder, and an organic solvent are mixed. Since it becomes uniform, deformation such as warping and dent after sintering does not occur, and pressure unevenness at the time of pressing is eliminated, so there is no need for correction processing after sintering, which has been done conventionally, and the manufacturing process It can be simplified. Thereby, a permanent magnet can be formed with high dimensional accuracy. Further, even when the permanent magnet is thinned, it is possible to prevent the processing man-hours from increasing without reducing the material yield.
  • the rare earth permanent magnet according to the present invention before the green sheet is calcined, the binder resin is scattered and removed by holding the green sheet at a binder resin decomposition temperature for a predetermined time in a non-oxidizing atmosphere. Therefore, the amount of carbon contained in the magnet can be reduced in advance. As a result, it is possible to suppress the precipitation of ⁇ Fe in the main phase of the magnet after sintering, to densely sinter the entire magnet, and to prevent the coercive force from being lowered.
  • the carbon sheet contained in the magnet is calcined in a hydrogen atmosphere or a mixed gas atmosphere of hydrogen and an inert gas by calcining a green sheet kneaded with a binder resin. The amount can be reduced more reliably.
  • wet pulverization is performed by wet pulverizing a magnet raw material and an organometallic compound in an organic solvent in a wet pulverization process that is a process for producing a rare earth permanent magnet. It becomes possible to improve the pulverization property. For example, most of the magnet raw material can be pulverized to a fine particle size range (for example, 0.1 ⁇ m to 5.0 ⁇ m). As a result, the crystal grain size after sintering can be reduced, and the magnetic performance of the manufactured rare earth permanent magnet can be improved.
  • the organometallic compound adheres to the particle surface of the magnet powder.
  • elements such as Nd, Al, Cu, Ag, Dy, Tb, V, Mo, Zr, Ta, Ti, W, Nb, etc.
  • the organometallic compound can be easily dissolved in a general-purpose solvent such as toluene, and the magnet powder can be appropriately attached to the particle surface.
  • an organometallic compound composed of an alkyl group is used as the organometallic compound to be added to the magnet powder, so that the organometallic compound can be easily pyrolyzed. Is possible. As a result, it is possible to more reliably reduce the amount of carbon in the molded body when calcining.
  • the permanent magnet is constituted by a magnet obtained by sintering a green sheet formed from a slurry in which magnet powder, a resin binder, and an organic solvent are mixed. Due to the uniform shrinkage caused by deformation, deformation such as warping and dent after sintering does not occur, and pressure unevenness at the time of pressing is eliminated, so there is no need for conventional post-sintering correction processing, The manufacturing process can be simplified. Thereby, a permanent magnet can be formed with high dimensional accuracy. Further, even when the permanent magnet is thinned, it is possible to prevent the processing man-hours from increasing without reducing the material yield.
  • the binder resin before calcining the green sheet, the binder resin is scattered by holding the green sheet at a binder resin decomposition temperature for a certain time in a non-oxidizing atmosphere. Therefore, the amount of carbon contained in the magnet can be reduced in advance. As a result, it is possible to suppress the precipitation of ⁇ Fe in the main phase of the magnet after sintering, to densely sinter the entire magnet, and to prevent the coercive force from being lowered.
  • the green sheet kneaded with the binder resin is calcined in a hydrogen atmosphere or a mixed gas atmosphere of hydrogen and an inert gas, so that it is contained in the magnet.
  • the amount of carbon to be reduced can be more reliably reduced.
  • FIG. 1 is an overall view showing a permanent magnet according to the present invention.
  • FIG. 2 is an enlarged schematic view showing the vicinity of the grain boundary of the permanent magnet according to the present invention.
  • FIG. 3 is a diagram for explaining the effect at the time of sintering based on the improvement of the thickness accuracy of the green sheet according to the present invention.
  • FIG. 4 is a diagram for explaining the effect during sintering based on the improvement of the thickness accuracy of the green sheet according to the present invention.
  • FIG. 5 is an explanatory view showing a manufacturing process of the permanent magnet according to the present invention.
  • FIG. 6 is an explanatory view showing a green sheet forming step in particular among the manufacturing steps of the permanent magnet according to the present invention.
  • FIG. 7 is an explanatory diagram showing the pressure-sintering step of the green sheet, among the manufacturing steps of the permanent magnet according to the present invention.
  • FIG. 8 is an enlarged photograph showing the magnet powder after wet pulverization of the permanent magnet of Example 1.
  • FIG. 9 is an enlarged photograph showing the magnet powder after wet pulverization of the permanent magnet of Example 2.
  • FIG. 10 is an enlarged photograph showing the magnet powder after wet pulverization of the permanent magnet of Example 3.
  • FIG. 11 is an enlarged photograph showing the magnet powder after wet pulverization for the permanent magnet of Comparative Example 1.
  • FIG. 1 is an overall view showing a permanent magnet 1 according to the present invention.
  • the permanent magnet 1 shown in FIG. 1 has a fan shape, but the shape of the permanent magnet 1 varies depending on the punched shape.
  • the permanent magnet 1 according to the present invention is an Nd—Fe—B based magnet.
  • the content of each component is Nd: 27 to 40 wt%, B: 1 to 2 wt%, and Fe (electrolytic iron): 60 to 70 wt%.
  • FIG. 1 is an overall view showing a permanent magnet 1 according to the present embodiment.
  • the permanent magnet 1 is a thin film-like permanent magnet having a thickness of, for example, 0.05 mm to 10 mm (for example, 4 mm). And it is produced by sintering the green sheet shape
  • the permanent magnet 1 has a portion of Nd in the surface portion (outer shell) of the crystal grains of the Nd crystal particles 2 constituting the permanent magnet 1 with Al, Cu, Ag, By generating the layer 3 (hereinafter referred to as the outer shell layer 3) substituted with Dy, Tb, V, Mo, Zr, Ta, Ti, W, Nb or the like, Make it unevenly distributed.
  • FIG. 2 is an enlarged view showing Nd crystal particles 2 constituting the permanent magnet 1.
  • substitution of Dy or the like is performed by adding an organometallic compound containing Dy or the like before forming a pulverized magnet powder as described below.
  • M- (OR) x wherein M is Nd, Al, Cu, Ag, Dy, Tb, V, Mo, Zr, Ta, Including at least one of Ti, W, and Nb, wherein R is a substituent composed of a hydrocarbon having a carbon chain length of 2 to 16, which may be linear or branched, and x is any integer.
  • An organometallic compound containing M represented (for example, niobium decanoxide, niobium tetradecanoxide, niobium butoxide, etc.) is added and mixed with the magnet powder in a wet state.
  • M represented for example, niobium decanoxide, niobium tetradecanoxide, niobium butoxide, etc.
  • the organometallic compound containing Dy or Tb is dispersed in an organic solvent, and the organometallic compound containing Dy or Tb is efficiently dispersed on the particle surface of the Nd magnet particle. It becomes possible to adhere. And when sintering the magnetic powder to which the organometallic compound containing Dy or Tb is added, the Dy or Tb in the organometallic compound uniformly adhered to the particle surface of the Nd magnet particles by wet dispersion becomes Nd magnet particles. Substitution is performed by diffusion and penetration into the crystal growth region, and a Dy layer or a Tb layer is formed as the outer shell layer 3 on the surface of the Nd crystal particle 2.
  • Dy or Tb can be unevenly distributed at the grain boundaries of the magnet particles.
  • the Dy layer is made of, for example, (Dy x Nd 1-x ) 2 Fe 14 B intermetallic compound. Then, Dy and Tb unevenly distributed at the grain boundaries suppress the generation of reverse magnetic domains at the grain boundaries, so that the coercive force can be improved.
  • the amount of Dy or Tb added can be reduced as compared with the conventional case, and a decrease in residual magnetic flux density can be suppressed.
  • M contains a refractory metal element such as V, Mo, Zr, Ta, Ti, W, or Nb (hereinafter referred to as Nb)
  • Nb a refractory metal element
  • an organometallic compound containing Nb or the like is dispersed in an organic solvent. It becomes possible to uniformly adhere an organometallic compound containing Nb or the like to the particle surface of the Nd magnet particle.
  • the magnet powder is sintered, Nb or the like in the organometallic compound uniformly adhered to the surface of the Nd magnet particles by wet dispersion diffuses and penetrates into the crystal growth region of the Nd crystal particles.
  • a refractory metal layer is formed as the outer shell layer 3 on the surface of the Nd crystal particle 2.
  • the refractory metal layer is made of, for example, an NbFeB intermetallic compound.
  • the refractory metal layer coated on the surface of the Nd crystal particles functions as a means for suppressing so-called grain growth in which the average particle diameter of the Nd crystal particles increases when the permanent magnet 1 is sintered. As a result, it is possible to suppress grain growth of crystal grains during sintering.
  • the crystal grain size of the Nd crystal particles 2 is preferably 0.1 ⁇ m to 5.0 ⁇ m.
  • the magnetic performance can be improved.
  • the crystal grain size is a single domain grain size, the magnetic performance of the permanent magnet 1 can be dramatically improved.
  • M- (OR) x (wherein M includes at least one of Nd, Al, Cu, Ag, Dy, Tb, V, Mo, Zr, Ta, Ti, W, and Nb.
  • R Is a substituent composed of a hydrocarbon having a carbon chain length of 2 to 16, which may be linear or branched.
  • X is an arbitrary integer.
  • a metal alkoxide is an organometallic compound satisfying the general formula: The metal alkoxide is represented by the general formula M- (OR) n (M: metal element, R: organic group, n: valence of metal or metalloid).
  • Nd, Pr, Dy, Tb, W, Mo, V, Nb, Ta, Ti, Zr, Ir, Fe, Co, Ni, Cu, Zn, Cd, Al, Ga, In, Ge, Sb, Y, lanthanide, etc. are mentioned.
  • Nd, Al, Cu, Ag, Dy, Tb, V, Mo, Zr, Ta, Ti, W, and Nb are particularly used.
  • the type of alkoxide is not particularly limited, and examples thereof include methoxide, ethoxide, propoxide, isopropoxide, butoxide, alkoxide having 4 or more carbon atoms, and the like.
  • those having a low molecular weight are used for the purpose of suppressing residual coal by low-temperature decomposition as described later.
  • the methoxide having 1 carbon atom is easily decomposed and difficult to handle, and moreover, since the alkoxide is used as a dispersant for wet grinding as described later, the carbon chain length of R is particularly preferably 2 to 16. Is preferably 6 to 14, more preferably 10 to 14 alkoxide. Specific examples include butoxide having a carbon chain length of 4, hexoxide having a carbon chain length of 6, decanoxide having a carbon chain length of 10, tetradecanoxide having a carbon chain length of 14, and the like.
  • the carbon chain length of the organometallic compound to be used is too long, the organometallic compound is difficult to dissolve in a general-purpose solvent such as toluene.
  • the carbon chain length is set to 16 or less, more preferably 14 or less, in order to uniformly attach the organometallic compound to the surface of the Nd magnet particle.
  • organometallic compound composed of an alkyl group if used, the organometallic compound can be more easily thermally decomposed. That is, in the present invention, M- (OR) x (wherein M is Nd, Al, Cu, Ag, Dy, Tb, V, Mo, Zr, Ta, Ti, At least one of W and Nb is included, R is an alkyl group having a carbon chain length (alkyl chain length) of 2 to 16, which may be linear or branched, and x is an arbitrary integer. It is desirable to use organometallic compounds.
  • the molded body is sintered under appropriate firing conditions, it is possible to prevent M from diffusing and penetrating (solid solution) into the main phase.
  • the substitution region by M can be made only the outer shell portion.
  • the core Nd 2 T 14 B intermetallic compound phase occupies a high volume ratio. Thereby, the fall of the residual magnetic flux density (magnetic flux density when the intensity of an external magnetic field is set to 0) of the magnet can be suppressed.
  • the permanent magnet 1 of this invention is produced by sintering the green sheet shape
  • pressure sintering is used as a method of sintering a green sheet. It is done.
  • pressure sintering include hot press sintering, hot isostatic pressing (HIP) sintering, ultra-high pressure synthetic sintering, gas pressure sintering, and discharge plasma (SPS) sintering.
  • HIP hot isostatic pressing
  • SPS discharge plasma
  • a sintering method that can reduce the warpage generated in the magnet after sintering. Therefore, in the present invention, among the above sintering methods, it is desirable to use uniaxial pressure sintering in which pressure is applied in the uniaxial direction and SPS sintering in which sintering is performed by current sintering.
  • SPS sintering is a sintering method in which a graphite sintering mold having a sintering object disposed therein is heated while being pressed in a uniaxial direction.
  • SPS sintering in addition to the thermal and mechanical energy used in general sintering by pulse current heating and mechanical pressure, electromagnetic energy due to pulse current and self-heating of the workpiece and The discharge plasma energy generated between the particles is used as a driving force for the sintering. Therefore, rapid heating / cooling is possible compared to atmosphere heating in an electric furnace or the like, and sintering can be performed in a lower temperature range.
  • a green body obtained by punching a green sheet into a desired product shape (for example, a fan shape shown in FIG. 1) is placed in a sintering mold of an SPS sintering apparatus.
  • the multiple (for example, 10 pieces) molded object 5 is arrange
  • the plurality of molded bodies 5 are arranged in one space, but may be arranged in different spaces for each molded body 5.
  • the punches that pressurize the compact 5 for each space are configured so as to be integrated between the spaces (that is, pressurization can be performed simultaneously).
  • the thickness accuracy of the green sheet is within ⁇ 5%, more preferably within ⁇ 3%, and even more preferably within ⁇ 1% of the design value.
  • the thickness accuracy of the green sheet is low (for example, ⁇ 5% or more with respect to the design value)
  • a plurality of (for example, ten) molded bodies 5 are simultaneously placed in the sintering mold 6 as shown in FIG.
  • the thickness d of each molded body 5 varies, so that an imbalance in the current flow of the pulse current for each molded body 5 occurs.
  • the binder resin kneaded with the magnetic powder when producing the green sheet includes polyisobutylene (PIB), butyl rubber (IIR), polyisoprene (IR), polybutadiene, polystyrene, and styrene-isoprene block.
  • PIB polyisobutylene
  • IIR butyl rubber
  • IR polyisoprene
  • polybutadiene polystyrene
  • polystyrene-isoprene block polymer
  • SBS Styrene-butadiene block copolymer
  • 2-methyl-1-pentene polymer resin 2-methyl-1-butene polymer resin
  • ⁇ -methylstyrene polymer resin polybutyl methacrylate
  • polymethyl Use methacrylate or the like polyisobutylene
  • the binder resin in order to reduce the amount of oxygen contained in the magnet, it is desirable to use a polymer (for example, polyisobutylene) made of hydrocarbon, having depolymerization properties and excellent in thermal decomposability. .
  • a resin other than polyethylene and polypropylene in order to appropriately dissolve the binder resin in a general-purpose solvent such as toluene, it is desirable to use a resin other than polyethylene and polypropylene as the binder resin.
  • the amount of binder resin added is an amount that appropriately fills the gaps between the magnet particles in order to improve the sheet thickness accuracy when the slurry is formed into a sheet.
  • the ratio of the binder resin to the total amount of magnet powder and binder resin in the slurry after addition of the binder resin is 4 wt% to 40 wt%, more preferably 7 wt% to 30 wt%, and even more preferably 10 wt% to 20 wt%. .
  • the magnet raw material is pulverized by wet pulverization such as a bead mill.
  • wet pulverization an organic solvent is generally used as a solvent for mixing the magnet raw material. Therefore, when producing a green sheet, it becomes possible to make magnet powder into a slurry form by adding binder resin in the organic solvent containing the ground magnet powder, for example.
  • the organic solvent used for wet pulverization include alcohols such as isopropyl alcohol, ethanol and methanol, lower hydrocarbons such as pentane and hexane, aromatics such as benzene, toluene and xylene, and esters such as ethyl acetate.
  • one or more organic solvents selected from organic compounds consisting of hydrocarbons are used for the purpose of reducing the amount of oxygen contained in the magnet as described later. It is desirable to use it.
  • the one or more organic solvents selected from organic compounds composed of hydrocarbons include toluene, hexane, pentane, benzene, xylene, and mixtures thereof.
  • toluene or hexane is used.
  • the organic solvent may contain a small amount of an organic compound other than the organic compound made of hydrocarbon.
  • the magnet raw material when the magnet raw material is pulverized by wet pulverization such as a bead mill, the above-described organometallic compound (for example, niobium decanoxide, niobium tetradecanoxide, niobium butoxide, etc.) is added as a dispersant.
  • the pulverization property of the wet pulverization is improved, and most of the magnet raw material can be pulverized to a fine particle size range (for example, 0.1 ⁇ m to 5.0 ⁇ m).
  • a fine particle size range for example, 0.1 ⁇ m to 5.0 ⁇ m.
  • the magnet powder may be made into a slurry by adding an organic solvent and a binder resin.
  • organic solvents selected from organic compounds that are also composed of hydrocarbons as the organic solvent added to the dried magnet powder.
  • FIG. 5 is an explanatory view showing a manufacturing process of the permanent magnet 1 according to the present embodiment.
  • an ingot made of a predetermined fraction of Nd—Fe—B (eg, Nd: 32.7 wt%, Fe (electrolytic iron): 65.96 wt%, B: 1.34 wt%) is manufactured. Thereafter, the ingot is roughly pulverized to a size of about 200 ⁇ m by a stamp mill or a crusher. Alternatively, the ingot is melted, flakes are produced by strip casting, and coarsely pulverized by hydrogen crushing. Thereby, coarsely pulverized magnet powder 10 is obtained.
  • Nd—Fe—B eg, Nd: 32.7 wt%, Fe (electrolytic iron): 65.96 wt%, B: 1.34 wt
  • the coarsely pulverized magnet powder 10 is finely pulverized into a predetermined range of particle size (for example, 0.1 ⁇ m to 5.0 ⁇ m) by a wet method using a bead mill, and the magnet powder is dispersed in a solvent to prepare a dispersion solution 11. Further, when pulverizing, an organometallic compound containing Nd, Al, Cu, Ag, Dy, Tb, V, Mo, Zr, Ta, Ti, W, or Nb is added as a dispersant to the solvent.
  • Detailed pulverization conditions by wet pulverization are as follows.
  • ⁇ Crushing device Bead mill
  • ⁇ Crushing media After grinding with ⁇ 2 mm zirconia beads for 2 hours, grinding with ⁇ 0.5 mm zirconia beads for 2 hours.
  • M- (OR) x (wherein M is Nd, Al, Cu, Ag, Dy, Tb, V, Mo, Zr, Ta, Ti, W, Nb) R is a substituent composed of a hydrocarbon having a carbon chain length of 2 to 16, which may be linear or branched, and x is an arbitrary integer)) (for example, Niobium decanoxide, niobium tetradecanoxide, niobium butoxide, etc.) are preferably used.
  • pulverization is an organic solvent
  • an organic solvent it is desirable to use the 1 or more types of organic solvent selected from the organic compound which consists of a hydrocarbon as mentioned above.
  • organic solvent there are toluene, hexane, pentane, benzene, xylene, a mixture thereof, and the like.
  • toluene or hexane is used.
  • the amount of the organometallic compound to be added is not particularly limited, but in order to properly function as a dispersant and to uniformly adhere the organometallic compound to the particle surface of the magnet powder, 0.1 part to The amount is 10 parts, preferably 0.2 to 8 parts, more preferably 0.5 to 5 parts (for example, 1 part).
  • a binder resin is further added to the dispersion solution 11. Thereby, a slurry 12 is produced in which a fine powder of a magnet raw material in which an organometallic compound is uniformly attached to the particle surface, a binder resin, and an organic solvent are mixed.
  • the binder resin it is desirable to use a polymer which is made of hydrocarbon as described above, has depolymerization properties, and is excellent in thermal decomposability. For example, polyisobutylene is used. Moreover, you may add binder resin in the state diluted with the solvent.
  • the amount of binder resin added is 4 wt% to 40 wt%, more preferably 7 wt% to 30 wt%, still more preferably the ratio of binder resin to the total amount of magnet powder and binder resin in the slurry after addition as described above. Is an amount of 10 wt% to 20 wt%.
  • the binder resin is added in an atmosphere made of an inert gas such as nitrogen gas, Ar gas, or He gas.
  • a green sheet 13 is formed from the generated slurry 12.
  • the produced slurry 12 can be applied by an appropriate method on a support substrate 14 such as a separator and dried as necessary.
  • the coating method is preferably a method having excellent layer thickness controllability such as a doctor blade method, a die method, or a comma coating method.
  • it is desirable to use a die method or a comma coating method that is particularly excellent in layer thickness controllability that is, a method capable of high accuracy on the base material.
  • a die method is used.
  • the support base material 14 for example, a silicone-treated polyester film is used.
  • the green sheet 13 is dried by holding at 90 ° C. for 10 minutes and then holding at 130 ° C. for 30 minutes. Furthermore, it is preferable to sufficiently defoam the mixture so that bubbles do not remain in the spreading layer by using an antifoaming agent in combination.
  • FIG. 6 is a schematic view showing a process of forming the green sheet 13 by a die method.
  • the die 15 used in the die system is formed by overlapping the blocks 16 and 17 with each other, and the slit 18 and the cavity (liquid reservoir) 19 are formed by a gap between the blocks 16 and 17.
  • the cavity 19 communicates with a supply port 20 provided in the block 17.
  • the supply port 20 is connected to a slurry supply system constituted by a metering pump (not shown) or the like, and the measured slurry 12 is supplied to the cavity 19 via the supply port 20 by a metering pump or the like. Is done.
  • the slurry 12 supplied to the cavity 19 is fed to the slit 18 and is discharged from the discharge port 21 of the slit 18 with a predetermined application width with a uniform amount in the width direction by a constant amount per unit time.
  • the support base material 14 is conveyed at a preset speed with the rotation of the coating roll 22. As a result, the discharged slurry 12 is applied to the support base material 14 with a predetermined thickness.
  • the thickness accuracy of the green sheet 13 to be formed is within ⁇ 5%, more preferably within ⁇ 3%, and even more preferably within ⁇ 1% with respect to the design value (for example, 4 mm).
  • the set thickness of the green sheet 13 is desirably set in the range of 0.05 mm to 10 mm.
  • the productivity must be reduced because multiple layers must be stacked.
  • the thickness is greater than 10 mm, it is necessary to reduce the drying speed in order to suppress foaming during drying, and productivity is significantly reduced.
  • a pulsed magnetic field is applied to the green sheet 13 coated on the support base material 14 in a direction crossing the transport direction before drying.
  • the intensity of the applied magnetic field is 5000 [Oe] to 50000 [Oe], preferably 10,000 [Oe] to 20000 [Oe].
  • the direction in which the magnetic field is oriented needs to be determined in consideration of the direction of the magnetic field required for the permanent magnet 1 formed from the green sheet 13, but is preferably in the in-plane direction.
  • the green sheet 13 formed from the slurry 12 is punched into a desired product shape (for example, a fan shape shown in FIG. 1), and a formed body 25 is formed.
  • a desired product shape for example, a fan shape shown in FIG. 1
  • the molded body 25 is maintained in hydrogen by holding it for several hours (for example, 5 hours) at a binder resin decomposition temperature in a non-oxidizing atmosphere (in particular, a hydrogen atmosphere or a mixed gas atmosphere of hydrogen and an inert gas in the present invention).
  • a non-oxidizing atmosphere in particular, a hydrogen atmosphere or a mixed gas atmosphere of hydrogen and an inert gas in the present invention.
  • Perform calcination In the case of performing in a hydrogen atmosphere, for example, the supply amount of hydrogen during calcination is set to 5 L / min.
  • the binder resin can be decomposed into monomers by a depolymerization reaction or the like and scattered to be removed. That is, so-called decarbonization for reducing the amount of carbon in the molded body 25 is performed.
  • the calcination treatment in hydrogen is performed under the condition that the carbon content in the molded body 25 is 1500 ppm or less, more preferably 1000 ppm or less. Accordingly, the entire permanent magnet 1 can be densely sintered by the subsequent sintering process, and the residual magnetic flux density and coercive force are not reduced.
  • the binder resin decomposition temperature is determined based on the analysis result of the binder resin decomposition product and decomposition residue. Specifically, a temperature range is selected in which decomposition products of the binder are collected, decomposition products other than the monomers are not generated, and products due to side reactions of the remaining binder components are not detected even in the analysis of the residues. Although it varies depending on the type of the binder resin, it is set to 200 ° C. to 900 ° C., more preferably 400 ° C. to 600 ° C. (eg 600 ° C.).
  • a sintering process is performed to sinter the molded body 25 that has been calcined by the calcining process in hydrogen.
  • sintering is performed by pressure sintering.
  • pressure sintering include hot press sintering, hot isostatic pressing (HIP) sintering, ultra-high pressure synthetic sintering, gas pressure sintering, and discharge plasma (SPS) sintering.
  • HIP hot isostatic pressing
  • SPS discharge plasma
  • FIG. 7 is a schematic view showing a pressure sintering process of the compact 25 by SPS sintering.
  • SPS sintering As shown in FIG. 7, first, the molded body 25 is placed on a graphite sintering die 31. Note that the above-described calcination treatment in hydrogen may also be performed in a state where the molded body 25 is installed in the sintering mold 31. Then, the compact 25 placed on the sintering die 31 is held in the vacuum champ 32, and an upper punch 33 and a lower punch 34 made of graphite are set.
  • the plurality of molded bodies 5 are arranged in one space, but may be arranged in different spaces for each molded body 5.
  • the upper punch 33 and the lower punch 34 that pressurize the molded body 5 for each space are configured so as to be integrated between the spaces (that is, pressure can be applied simultaneously).
  • Specific sintering conditions are shown below. Pressurized value: 30 MPa Sintering temperature: raised to 940 ° C. at 10 ° C./min and held for 5 minutes
  • Atmosphere vacuum atmosphere of several Pa or less
  • toluene was used as an organic solvent for wet grinding.
  • 1 part of Nb decanoxide Nb (OC 10 H 21 ) 5
  • the pulverization was first pulverized with ⁇ 2 mm zirconia beads for 2 hours, and then pulverized with ⁇ 0.5 mm zirconia beads for 2 hours.
  • polyisobutylene was used as a binder resin to be added when the slurry was generated, and a slurry in which the ratio of the resin in the slurry after the addition was 16.7 w% was generated. Thereafter, the slurry was applied to a substrate by a die method to form a green sheet, and further punched into a desired product shape. The other steps are the same as those described in the above [Permanent magnet manufacturing method].
  • Example 2 The organometallic compound to be added when wet grinding was Nb tetradecanoxide (Nb (OC 14 H 29 ) 5 ). Other conditions are the same as in the example.
  • Example 3 The organometallic compound added when performing wet grinding was Nb butoxide (Nb (OC 4 H 9 ) 5 ). Other conditions are the same as in the example.
  • FIG. 8 to 11 are enlarged photographs showing magnet powders after wet pulverization of the permanent magnets of Examples 1 to 3 and Comparative Example 1.
  • FIG. 8 to 11 the particle size distribution of each magnet powder was measured, and D50 (median diameter) was calculated. Comparing each of the enlarged photographs of Examples 1 to 3 and Comparative Example 1, compared to Comparative Example 1 in which no organometallic compound was added in wet grinding, Examples 1 to 3 in which organometallic compound was added in wet grinding. Then, it turns out that the magnet raw material has been grind
  • Examples 1 to 3 D50 was 1.7 ⁇ m, 2.0 ⁇ m, and 3.7 ⁇ m, respectively, and most of the magnet raw material could be pulverized into a magnet powder having a particle size of 0.1 ⁇ m to 5.0 ⁇ m. Yes.
  • Comparative Example 1 D50 was 8.0 ⁇ m, indicating that the magnet raw material could not be pulverized to a magnet powder having a particle size of 0.1 ⁇ m to 5.0 ⁇ m.
  • the permanent magnets of Examples 1 to 3 can have a smaller crystal grain size after sintering than the permanent magnet of Comparative Example 1, and can improve the magnetic performance.
  • Nb1-eicosoxide which is an organometallic compound
  • Nb1-eicosoxide could not be dissolved in toluene. Therefore, it can be seen that when the carbon chain length of the organometallic compound is too long, the organometallic compound is difficult to dissolve in a general-purpose solvent such as toluene.
  • the added organometallic compound functions as a dispersant and improves the grindability of wet grinding.
  • an organometallic compound having a substituent R having a carbon chain length of 2 to 16 is used as the organometallic compound, most of the magnet raw material is 0.1 ⁇ m to while the organometallic compound is uniformly attached to the surface of the magnet particle. It turns out that it becomes possible to grind
  • Example 2 can pulverize the magnet raw material to a smaller particle size than Example 3, and Example 1 further pulverizes the magnetic material to a smaller particle size than Example 2. is made of. Therefore, compared with Nb butoxide having a carbon chain length of the substituent R of 4, Nb decanoxide having a carbon chain length of the substituent R of 10 or Nb tetradecanoxide having a carbon chain length of 14 is used for wet grinding. It can be seen that it is possible to improve the pulverization property.
  • the grindability of wet grinding varies depending on the carbon chain length of the substituent R of the organometallic compound to be added, and the carbon chain length is 2 to 16, more preferably 6 to 14, and even more preferably 10 to 14. As a result, the pulverizability can be improved.
  • the coarsely pulverized magnet powder and the general formula M- (OR) x (where M is Nd, Al, Cu, It contains at least one of Ag, Dy, Tb, V, Mo, Zr, Ta, Ti, W, and Nb, where R is a substituent composed of a hydrocarbon having a carbon chain length of 2 to 16, Branches may be used.
  • X is an arbitrary integer.
  • the permanent magnet 1 is manufactured by shaping
  • wet pulverization process which is a manufacturing process of the permanent magnet
  • wet pulverization can be improved by wet pulverizing the magnet raw material and the organometallic compound in an organic solvent.
  • most of the magnet raw material can be pulverized to a fine particle size range (for example, 0.1 ⁇ m to 5.0 ⁇ m). As a result, the crystal grain size after sintering can be reduced, and the magnetic performance can be improved.
  • the organometallic compound can be easily dissolved in a general-purpose solvent such as toluene, and the magnet powder is appropriately attached to the particle surface. It becomes possible. Also, by adding an organometallic compound containing Nd, Al, Cu, Ag, Dy, Tb, V, Mo, Zr, Ta, Ti, W, Nb, etc., the organometallic compound adheres to the particle surface of the magnet powder. In the case where elements such as Nd, Al, Cu, Ag, Dy, Tb, V, Mo, Zr, Ta, Ti, W, and Nb are added to improve the magnet characteristics. Each element can be efficiently distributed with respect to the grain boundary of the magnet.
  • the magnetic characteristics of the permanent magnet to be manufactured can be improved, and the amount of each element added can be made smaller than in the prior art, so that a decrease in residual magnetic flux density can be suppressed.
  • the permanent magnet is manufactured by sintering a green sheet formed from a slurry in which magnet powder, a resin binder, and an organic solvent are mixed, the manufactured permanent magnet is uniformly contracted by sintering. Because there is no deformation such as warping or dent after sintering, and pressure unevenness at the time of pressing is eliminated, there is no need for correction processing after sintering, which has been done conventionally, and the manufacturing process is simplified Can do. Thereby, a permanent magnet can be formed with high dimensional accuracy.
  • the binder resin is scattered and removed by performing a calcination process in which the green sheet is kept at the binder resin decomposition temperature for a certain period of time in a non-oxidizing atmosphere.
  • the amount of carbon contained therein can be reduced in advance. As a result, it is possible to suppress the precipitation of ⁇ Fe in the main phase of the magnet after sintering, to densely sinter the entire magnet, and to prevent the coercive force from being lowered.
  • the organometallic compound when an organometallic compound composed of an alkyl group is used as the organometallic compound to be added, the organometallic compound can be thermally decomposed at a low temperature when calcining the magnet powder in a hydrogen atmosphere. Thereby, the thermal decomposition of the organometallic compound can be more easily performed on the entire magnet particle. Further, in the calcining treatment, the green sheet kneaded with the binder resin is held at 200 ° C. to 900 ° C., more preferably 400 ° C. to 600 ° C. for a certain time in a hydrogen atmosphere or a mixed gas atmosphere of hydrogen and an inert gas. Therefore, the amount of carbon contained in the magnet can be more reliably reduced.
  • the pulverization conditions, kneading conditions, calcination conditions, sintering conditions, etc. of the magnet powder are not limited to the conditions described in the above examples.
  • the magnet powder is made into a slurry to produce a green sheet, and the green sheet is sintered to produce a permanent magnet.
  • the powder after the wet-pulverized magnet powder is dried. It is good also as sintering by a sintering method and producing a permanent magnet.
  • the green sheet is formed by the die method, but the green sheet is formed by using another method (for example, comma coating method, injection molding, mold molding, doctor blade method, etc.). Also good. However, it is desirable to use a system that can apply the slurry to the substrate with high accuracy. Further, the sintering method is not limited to pressure sintering, and may be sintered by vacuum firing. Moreover, in the said Example, although the wet bead mill is used as a means to wet pulverize magnet powder, you may use another wet pulverization system. For example, a nanomizer or the like may be used.
  • the magnet powder is made into a slurry by adding a binder resin to an organic solvent containing the pulverized magnet powder.
  • the magnet powder may be made into a slurry by adding an organic solvent and a binder resin.
  • toluene or hexane is used as the organic solvent added to the magnet powder, but other organic solvents may be used.
  • pentane, benzene, xylene, or a mixture thereof may be used.
  • Examples 1 and 2 as an organometallic compound containing Nd, Al, Cu, Ag, Dy, Tb, V, Mo, Zr, Ta, Ti, W, Nb, etc. added to the organic solvent during wet grinding.
  • Niobium decanoxide and niobium butoxide are used, but M- (OR) x (wherein M is Nd, Al, Cu, Ag, Dy, Tb, V, Mo, Zr, Ta, Ti, W, Nb R is a substituent composed of a hydrocarbon having a carbon chain length of 2 to 16, which may be linear or branched, and x is an arbitrary integer.) Any other organometallic compound may be used. Further, M may be configured to include an element other than the metal element.
  • the Nd—Fe—B system magnet has been described as an example, but other magnets may be used. Further, in the present invention, the Nd component is larger than the stoichiometric composition in the present invention, but it may be stoichiometric.

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PCT/JP2012/074471 2011-09-30 2012-09-25 希土類永久磁石及び希土類永久磁石の製造方法 Ceased WO2013047467A1 (ja)

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JP6511779B2 (ja) * 2014-11-12 2019-05-15 Tdk株式会社 Ｒ−ｔ−ｂ系焼結磁石
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KR20140082741A (ko) 2014-07-02
US20140241929A1 (en) 2014-08-28
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