WO2017018252A1 - Procédé de fabrication d'aimant fritté de terres rares - Google Patents

Procédé de fabrication d'aimant fritté de terres rares Download PDF

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Publication number
WO2017018252A1
WO2017018252A1 PCT/JP2016/071015 JP2016071015W WO2017018252A1 WO 2017018252 A1 WO2017018252 A1 WO 2017018252A1 JP 2016071015 W JP2016071015 W JP 2016071015W WO 2017018252 A1 WO2017018252 A1 WO 2017018252A1
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Prior art keywords
coating film
sintered magnet
heat treatment
rtb
powder
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PCT/JP2016/071015
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English (en)
Japanese (ja)
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三野　修嗣
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日立金属株式会社
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Priority to JP2017530789A priority Critical patent/JP6604381B2/ja
Priority to CN201680037646.4A priority patent/CN107710360B/zh
Publication of WO2017018252A1 publication Critical patent/WO2017018252A1/fr

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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
    • B22F3/24—After-treatment of workpieces or articles
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C28/00—Alloys based on a metal not provided for in groups C22C5/00 - C22C27/00
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
    • C23C10/28—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes
    • C23C10/34—Embedding in a powder mixture, i.e. pack cementation
    • C23C10/52—Embedding in a powder mixture, i.e. pack cementation more than one element being diffused in one step
    • 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
    • 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
    • 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

Definitions

  • the present disclosure relates to a method for manufacturing a rare earth sintered magnet.
  • An RTB-based sintered magnet mainly composed of an R 2 T 14 B-type compound is known as the most powerful magnet among permanent magnets, such as a voice coil motor (VCM) of a hard disk drive, It is used for various motors such as motors for hybrid vehicles and home appliances.
  • VCM voice coil motor
  • H cJ the intrinsic coercive force H cJ
  • H cJ the intrinsic coercive force
  • the RTB-based sintered magnet is known to improve H cJ when a part of R in the R 2 T 14 B-type compound phase is substituted with a heavy rare earth element RH (Dy, Tb). .
  • a heavy rare earth element RH Dy, Tb
  • the light rare earth element RL Nd, Pr
  • B r residual magnetic flux density
  • Patent Document 1 discloses the use of R oxide, R fluoride, and R oxyfluoride powders.
  • Patent Document 2 discloses using a powder of an RM (M is one or more selected from Al, Cu, Zn, Ga, etc.) alloy.
  • Patent Documents 3 and 4 are RM alloys (M is one or more selected from Al, Cu, Zn, Ga, etc.), M1M2 alloys (M1M2 is one or more selected from Al, Cu, Zn, Ga, etc.), and It is disclosed that by using a mixed powder of RH oxide, it is possible to partially reduce the RH oxide with an RM alloy or the like during heat treatment and introduce the heavy rare earth element RH into the magnet.
  • the powder is present on the surface of the sintered magnet, typically, a slurry in which the powder is dispersed in water or an organic solvent is prepared, and the sintered magnet is contained in this slurry. After soaking, it is dried. Moreover, the method of apply
  • the present inventor examined a method of applying a paste obtained by mixing these powders with a binder to the surface of the sintered magnet, and the coating film was peeled off from the surface of the sintered magnet during the heat treatment, and the powder contained in the peeled portion. It has been found that the problem that medium elements do not sufficiently diffuse inside the sintered magnet can occur.
  • the embodiment of the present disclosure makes it possible to diffuse a desired element from the powder particles contained in the coating film into the coating object with good reproducibility.
  • a method of manufacturing a rare earth sintered magnet according to the present disclosure includes a step of preparing an RTB based sintered magnet, a coating film of a paste including a mixed powder in which a metal powder and a metal compound powder are mixed, and a resin binder. Is formed on the surface of the RTB-based sintered magnet, and the RTB-based sintered magnet having the coating film formed on the surface is subjected to a heat treatment.
  • the value obtained by subtracting the carbon content before the heat treatment of the mixed powder contained in the paste is in the range of 0.07% by mass or more and 0.50% by mass or less of the entire coating film after the heat treatment. So that the heat treatment Carbon content of the coating film is adjusted in.
  • the ratio of the mixed powder to the entire dried coating film before the heat treatment is 95% by mass or more and 99% by mass or less.
  • the mixed powder includes a metal powder of an RLM alloy (RL is Nd and / or Pr, M is one or more selected from Cu, Fe, Ga, Co, and Ni), and RH fluoride (RH is Dy and / or Tb), RH oxyfluoride, and at least one metal compound powder of RH oxide.
  • RLM alloy RL is Nd and / or Pr
  • M is one or more selected from Cu, Fe, Ga, Co, and Ni
  • RH fluoride RH is Dy and / or Tb
  • RH oxyfluoride RH oxyfluoride
  • the RLM alloy powder is not less than 50 mass% and not more than 96 mass% of the entire mixed powder.
  • the paste contains a coupling agent.
  • the residual carbon content was measured for a film that was heat-treated under the same conditions as the heat treatment step after peeling the film of the paste dried on the member that does not react with the paste from the member. Defined as content.
  • the coating film of the paste in which the powder and the binder are mixed is prevented from being peeled off by the heat treatment process, it is possible to diffuse a desired element from the powder in the coating film to the target. Can be realized well.
  • the coating film of the powder paste is suppressed or prevented from peeling from the surface of the sintered magnet, a desired metal element in the powder diffuses into the sintered magnet with a high yield, thereby improving HcJ . Effect can be obtained.
  • FIG. 2 is a cross-sectional view schematically showing a state after a paste coating film 200 is formed on the surface of an RTB-based sintered magnet 100 and a drying process is performed. It is sectional drawing which shows the coating film 200 after performing a binder removal process. It is sectional drawing which shows the state of the coating film 200 after hold
  • FIG. 3 is a cross-sectional view schematically showing a state in which heat treatment has progressed and metal in the coating film 200 has diffused from the surface of the RTB-based sintered magnet 100 into the magnet. It is sectional drawing which shows typically the part in which peeling of the coating film 200 produced in the middle of heat processing.
  • FIG. 3 is a perspective view showing the position of a magnet piece cut out from an RTB-based sintered magnet 100 with broken lines in order to measure magnet characteristics. It is the graph which showed the ratio of the mixed powder of Table 2, and the residual C amount (what subtracted mixed powder containing C amount) of Table 3 according to the kind of binder and coupling agent.
  • the binder in the paste is indispensable from the viewpoint of improving the application efficiency and making the application amount uniform.
  • the components in the binder mainly carbon (hereinafter simply referred to as “C”), are not necessary for improving the magnetic properties by diffusion of the metal element.
  • C is an impurity, and if contained in the magnet, it adversely affects the magnetic properties. For this reason, as long as the paste can be applied efficiently and uniformly, the role of the binder is completed, and it is important that the binder is removed as completely as possible in the heat treatment process.
  • the present inventor has intensively studied in order to solve the problem that the coating film for metal element diffusion is peeled off during the heat treatment as described above, and the diffusion component in the coating film is not sufficiently diffused in the magnet.
  • the coating film is peeled off by intentionally leaving a binder component, that is, C having an appropriate concentration in the coating film in a certain amount even during the diffusion heat treatment after completion of the binder removal.
  • the inventors have found that it can be suppressed or prevented and have come up with the present invention.
  • FIG. 1A is a sectional view schematically showing a state after a paste coating film 200 is formed on the surface of an RTB-based sintered magnet 100 and a drying process is performed.
  • a coating film (dry film) 200 a large number of metal powder particles 22 and metal compound powder particles 24 exist in the resin binder 20 that spreads in a film shape along the surface of the RTB-based sintered magnet 100.
  • the coating film 200 immediately after application has an appropriate viscosity that is easy to apply and still maintains sufficient fluidity, but the fluidity is lost by performing the drying process.
  • FIG. 1B shows a cross section of the coating film 200 after performing the binder removal process at the temperature T1. Although most of the resin binder 20 of the coating film 200 is lost due to thermal decomposition or evaporation due to the binder removal process, the metal powder particles 22 and the metal compound powder particles 24 in the coating film (dry film) 200 are retained by the remaining portion. Is done. The coating film (dry film) 200 is adhered or fixed to the surface of the RTB-based sintered magnet 100.
  • FIG. 1C shows the state of the coating film 200 after heat treatment at a temperature (T3) exceeding the melting point (T2) of the metal powder particles 22.
  • T3 a temperature exceeding the melting point of the metal powder particles 22.
  • the coating film 200 When the coating film 200 is peeled off, the coating film 200 is warped in the vicinity of the temperature T2, and peeling starts to occur.
  • the coating film 200 When the coating film 200 is formed on, for example, the upper surface of the RTB-based sintered magnet, the coating film 200 that starts to warp near the temperature T2 is softened in the process in which the heat treatment temperature further rises and reaches the temperature T3. Then, it may happen that it naturally adheres again to the upper surface of the RTB-based sintered magnet.
  • the coating film 200 when the coating film 200 is formed on the side surface of the RTB-based sintered magnet, the coating film 200 that starts to warp near the temperature T2 adheres again to the side surface of the RTB-based sintered magnet. There is nothing.
  • the coating film 200 when the coating film 200 is formed on the lower surface of the RTB-based sintered magnet, when the RTB-based sintered magnet is supported on a flat surface, the RTB When the space is present below the RTB-based sintered magnet, such as when supported by a rod-like or mesh-like support member, although warpage and peeling are not likely to occur due to the weight of the sintered magnet, Part of the film will peel off and will not adhere again.
  • the heat treatment proceeds at the temperature (T3), and the metal in the coating film 200 (for example, M derived from the RLM alloy that is metal powder particles or RH derived from the RH compound that is metal compound powder particles) is RT— A mode that it has diffused from the surface of B system sintered magnet 100 to the inside of a magnet is shown typically. At this time, rare earth elements diffuse from the inside of the RTB-based sintered magnet 100 to the surface, and mutual diffusion occurs. In this way, the metal component in the coating film can be diffused into the RTB-based sintered magnet by performing a heat treatment on the RTB-based sintered magnet having the coating film formed on the surface. It becomes possible.
  • FIG. 2 is a cross-sectional view schematically showing a part where the coating film 200 has been peeled off during the heat treatment.
  • FIG. 3 schematically shows the state of the heat treatment temperature T3 in the portion where the coating film 200 is peeled off.
  • FIGS. 2 and 3 when peeling occurs in the coating film 200, a gap is generated between the coating film 200 and the RTB-based sintered magnet 100, so that the coating film 200 is included.
  • the metal component cannot be uniformly diffused into the RTB-based sintered magnet 100.
  • a method for producing a rare earth-based sintered magnet in a non-limiting exemplary embodiment of the present disclosure includes a step of preparing an RTB-based sintered magnet, and a paste coating film including a mixed powder and a resin binder Forming on the surface of the RTB-based sintered magnet.
  • This mixed powder is a powder in which the metal powder and the metal compound powder are mixed. Note that the “metal” of the metal powder does not have to be composed of one kind of metal element, and may be “metal alloy”.
  • the metal component in the coating film is converted to R— by performing heat treatment on the RTB based sintered magnet having the coating film formed on the surface. And a step of diffusing inside the TB sintered magnet.
  • the coating film contains carbon (residual C) remaining after the heat treatment step.
  • the value obtained by subtracting the carbon content before heat treatment of the mixed powder contained in the paste from the carbon content (residual C amount) remaining in the coating film after the heat treatment is 0 for the entire coating film after the heat treatment.
  • the carbon content of the coating film before the heat treatment is adjusted so as to be in the range of 0.07 mass% or more and 0.50 mass% or less.
  • the value obtained by subtracting the carbon content before heat treatment of the mixed powder contained in the paste from the carbon content (residual C amount) remaining in the coating film after heat treatment is the value of the coating film after heat treatment. It exists in the range of 0.07 mass% or more and 0.50 mass% or less of the whole.
  • the content (mass) of carbon remaining in the coating film after the heat treatment step is X
  • the carbon content (mass) of the mixed powder contained in the paste before the heat treatment is Y
  • Z is the total mass of the coating film after the heat treatment.
  • the carbon content of the paste before the heat treatment depends on the amount of carbon contained in a composition such as a mixed powder and a resin binder constituting the paste.
  • part of the carbon in the paste disappears due to thermal decomposition or evaporation due to the heat treatment, so that the amount of carbon contained in the coating film after the heat treatment may vary depending on the temperature and time of the heat treatment.
  • the coating film is peeled only when (XY) / Z finally obtained is in a narrow range of 0.07% by mass or more and 0.50% by mass or less. It was found that it was prevented.
  • a paste coating film is formed on the surface of an actual rare earth sintered magnet, the mixed powder reacts with the rare earth sintered magnet during the heat treatment, so it is difficult to correctly measure the values of X and Z. possible. Therefore, according to the present disclosure, when determining the value of (XY) / Z, a paste coating film is formed on the surface of a substance having low reactivity with the mixed powder, and after performing a predetermined heat treatment, Measure X and Z.
  • the substance having low reactivity with the mixed powder is optional, but for example, a resin film such as PET (polyethylene terephthalate) having a thickness of about 0.05 mm to 0.2 mm can be used.
  • Paste preparation As described above, the carbon content (mass) X remaining in the coating film after the heat treatment step, the carbon content (mass) Y before heat treatment of the mixed powder contained in the paste, and the heat treatment
  • the binder type, the mixed powder, and the like so that the index value (XY) / Z expressed by the total mass Z of the coating film later falls within the range of 0.07% by mass to 0.50% by mass.
  • the amount of coupling, the type of coupling agent to be added, the amount added, etc. are adjusted.
  • the paste may be mixed with an organic solvent or water to adjust the viscosity of the paste. Since C in the organic solvent is almost completely evaporated and removed when the coating film is dried, the amount of C is not affected.
  • the type of binder and the type of coupling agent that can be added as necessary are not particularly limited.
  • PVA or ethyl cellulose can be used as the binder, and a silane coupling agent, titanate coupling agent, aluminate coupling agent, or the like can be used as the coupling agent.
  • the blending ratio of the mixed powder, binder, and coupling agent can be adjusted so that the mixed powder occupies 95 to 99% of the total in the dry film state.
  • the addition amount of the coupling agent can be blended so as to be 0 to 85% with respect to the resin as the binder.
  • (XY) / Z is not always included in the range of 0.07% by mass or more and 0.50% by mass or less. This is because the amount of residual C varies depending on the type of binder and coupling agent. Therefore, it is necessary to obtain (XY) / Z by measuring the amount of residual C after heat treatment by changing the kind and blending ratio of the mixed powder, binder, and coupling agent that actually constitute the paste. Then, the paste conditions may be selected such that the obtained (XY) / Z is in the range of 0.07 mass% to 0.50 mass%.
  • the spatial distribution and concentration of components in the coating film on the surface of the RTB-based sintered magnet may change during the heat treatment. This is because the metal component in the coating film is affected by diffusion into the RTB-based sintered magnet. As a result, it has been found that each component does not necessarily exist uniformly in the thickness direction in the coating film. Specifically, the carbon concentration in the coating film tends to be higher in the surface layer portion on the opposite side from the magnet surface than on the side in contact with the magnet surface. Further, when peeling does not occur in the coating film, it is extremely difficult to measure the amount of C in the coating film by removing only the coating film from the surface of the RTB-based sintered magnet. For this reason, it is difficult to accurately measure the amount of residual C in the coating film on the surface of the RTB-based sintered magnet.
  • a paste is applied on a resin film and dried to obtain a dry film (a film obtained by drying the paste coating film). And after heat-processing this dry film
  • the amount of residual C can be determined by measuring at the end of heat treatment.
  • the amount of C in the dry film hardly changes from the start of heat treatment (when the magnet temperature reaches the heat treatment temperature) to the end of heat treatment.
  • the amount of C in the dry film hardly changes even after the binder removal treatment performed before the heat treatment is completed until the heat treatment is completed. Therefore, even if the amount of C in the dry film is measured during these periods, the amount of residual C at the end of the heat treatment can be accurately estimated.
  • the carbon content (residual C amount) remaining in the coating film even after the heat treatment step is determined at an arbitrary timing in the period from the end of the binder removal treatment before the heat treatment to the end of the heat treatment for diffusion. Can be measured.
  • the value of “residual carbon content” (residual carbon content) after the heat treatment step is clearly defined, and therefore the “residual carbon content” value does not react with the paste. It is defined as the carbon content measured for a film that has been subjected to the heat treatment under the same conditions as in the heat treatment step after peeling off the paste film (paste dry film) from the member.
  • the mixed powder contained in the paste is a powder in a state where the metal powder and the metal compound powder are mixed.
  • the content of the mixed powder varies depending on what metal element is introduced into the RTB-based sintered magnet.
  • a specific example of the mixed powder will be described below by taking an example in which the heavy rare earth element RH is diffused into the RTB-based sintered magnet.
  • RLM alloy powder that functions as a diffusion aid can be used.
  • RL a light rare earth element having a high effect of reducing the RH compound is suitable. Further, RL is also sometimes M also has the effect of diffused into the magnet to improve the H cJ, tends to reduce the spread easily B r to the main phase crystal grains inside the element should be avoided. From the viewpoint of high effect of reducing this RH compound and difficulty in diffusing into the main phase crystal grains, RL is one or more selected from Nd and / or Pr, M is selected from Cu, Fe, Ga, Co, Ni, and Al.
  • the RLM alloy uses an alloy containing RL at 50 atomic% or more and having a melting point equal to or lower than the heat treatment temperature.
  • Such an RLM alloy efficiently reduces the RH compound during the heat treatment, and the RH reduced at a higher rate diffuses into the RTB-based sintered magnet so that the RTB system can be efficiently used even in a small amount.
  • the H cJ of the sintered magnet can be improved.
  • the particle size of the RLM alloy powder is preferably 500 ⁇ m or less.
  • RH is Dy and / or Tb
  • the RH compound is one or more selected from RH fluoride, RH oxide, and RH oxyfluoride
  • RH fluoride is preferable because it is easily reduced by the RLM alloy and has a large effect of improving HcJ .
  • the particle size of the RH compound powder is preferably 100 ⁇ m or less.
  • the RH oxyfluoride in the present invention may be included in the RH fluoride as an intermediate substance in the production process of the RH fluoride.
  • RH diffuses into the RTB -based sintered magnet, and H cJ can be greatly improved with a small amount of RH.
  • a powder (third powder) other than the powder of the RLM alloy and the RH compound is present on the surface of the RTB-based sintered magnet. Care must be taken not to inhibit diffusion of RH in the RH compound into the RTB-based sintered magnet.
  • the mass ratio of the “RLM alloy and RH compound” powder in the entire powder existing on the surface of the RTB-based sintered magnet is desirably 70% or more.
  • RTB-based sintered magnet base material An RTB-based sintered magnet base material to be diffused of the heavy rare earth element RH is prepared.
  • an RTB-based sintered magnet that is a target of diffusion of the heavy rare earth element RH may be strictly referred to as an RTB-based sintered magnet base material.
  • the term “RTB-based sintered magnet” includes such “RTB-based sintered magnet base material”.
  • a known material can be used, for example, having the following composition.
  • Rare earth element R 12 to 17 atomic% B (a part of B (boron) may be substituted with C (carbon)): 5 to 8 atomic%
  • Additive element M ′ selected from the group consisting of Al, Ti, V, Cr, Mn, Ni, Cu, Zn, Ga, Zr, Nb, Mo, Ag, In, Sn, Hf, Ta, W, Pb, and Bi At least one kind): 0 to 2 atomic% T (which is a transition metal element mainly containing Fe and may contain Co) and inevitable impurities: the balance
  • the rare earth element R is mainly composed of at least one kind selected from light rare earth elements RL (Nd, Pr) Element), but may contain heavy rare earth elements. In addition, when a heavy rare earth element is contained, it is preferable that at least one of Dy and Tb is included.
  • the RTB-based sintered magnet base material having the above composition is manufactured by an arbitrary manufacturing method.
  • Examples of a method for forming a coating film on the surface of the RTB-based sintered magnet may include a coating method (printing method), a dipping method, a spray method, and the like.
  • the thickness of the coating film can be set in the range of 0.05 to 0.5 mm, for example.
  • the amount of RH element in the powder present on the surface of the RTB-based sintered magnet is preferably 0.03 to 0.35 mg, preferably 0.05 to 0.25 mg per 1 mm 2 of the magnet surface. More preferably.
  • the thickness of the coating film can be adjusted to realize such a value.
  • the coating film is held at a temperature of, for example, 80 to 100 ° C. for 30 minutes to 3 hours and dried.
  • the coating film is heat-treated at a temperature (T1) of 350 to 450 ° C. for 1 to 4 hours, for example.
  • T1 a temperature of 350 to 450 ° C. for 1 to 4 hours, for example.
  • a heat treatment is performed at a temperature (T3) exceeding the melting point (T2) of the metal powder particles contained in the coating film, for example, 500 to 1000 ° C. Are diffused from the surface of the RTB-based sintered magnet to the inside.
  • the heat treatment can be performed in a state in which the powder of the RLM alloy and the powder of the RH compound are present on the surface of the RTB-based sintered magnet. Since the RLM alloy powder melts after the start of the heat treatment, it is not necessary for the RLM alloy to always maintain a “powder” state during the heat treatment.
  • the atmosphere for the heat treatment is preferably a vacuum or an inert gas atmosphere.
  • the surface of the coating film is ground to a depth of, for example, about 50 to 500 ⁇ m, and the coating film and the surface layer of the RTB-based sintered magnet are removed.
  • Example 1 -Measurement of C amount Mixed powder, binder, coupling agent, and solvent were blended under the conditions shown in Table 1 below to prepare a paste. These blending ratios are shown as mass% (mass%) in Table 1.
  • the mixed powder in this example was prepared by mixing RLM alloy powder and RH fluoride powder at a mass ratio of 60:40.
  • the RLM alloy powder is composed of Nd 70 Cu 30 alloy particles having a particle size of 150 ⁇ m or less prepared by a centrifugal atomization method.
  • the RH fluoride powder is composed of TbF 3 particles having a particle size of 100 ⁇ m or less.
  • the binder used in this example is EC (ethyl cellulose) or PVA (polyvinyl alcohol).
  • the coupling agent is an epoxy SC (silane coupling agent), an amino SC, an amino TC (titanate coupling agent), a vinyl SC, an alkyl SC, or a methacrylic SC.
  • the solvent was ethanol when the binder was ethyl cellulose, and pure water when the binder was polyvinyl alcohol.
  • the prepared paste was applied to a PET film having a thickness of 70 ⁇ m and dried at 90 ° C. for 1 hour.
  • the paste after drying is referred to as “dry film”.
  • Table 2 shows the ratio of each component in the dried film obtained by calculation.
  • the dried film was placed on a Mo plate, heated from room temperature to 400 ° C. at 10 ° C./min in a heat treatment apparatus, and heat treated at 400 ° C. for 2 hours. Thereafter, the temperature was further raised to 900 ° C. at 10 ° C./min, followed by heat treatment at 900 ° C. for 8 hours.
  • These heat treatment conditions are set to be the same as the heat treatment conditions performed after the paste is actually applied to the surface of the RTB-based sintered magnet to form a coating film.
  • the amount of residual C in the sample obtained by cooling after the heat treatment was measured with a high-frequency induction heating carbon analyzer (Horiba, Ltd .: EMIA-920V2).
  • Table 3 shows the amount of residual C in the sample, the amount of C contained in the mixed powder before the heat treatment, and the difference between them.
  • a B-type sintered magnet was produced. This was machined to obtain an RTB-based sintered magnet base material of 5.7 mm ⁇ 15.6 mm ⁇ 70.2 mm. Magnetic properties of the obtained R-T-B based sintered magnet base material where a measured by B-H tracer, H cJ is 1052kA / m, B r was 1.45 T. The amount of impurities in the RTB-based sintered magnet base material was measured with a gas analyzer, and as a result, oxygen was 740 ppm, nitrogen was 490 ppm, and carbon was 880 ppm.
  • a paste prepared with the types and blending ratios shown in Table 1 was applied to the surface of the above-mentioned RTB-based sintered magnet base material having a size of 15.6 mm ⁇ 70.2 mm by screen printing.
  • the coating amount was adjusted so that the amount of Tb per mm 2 was 0.07 mg. After application, it was dried at 90 ° C. for 1 hour.
  • the paste was applied to the opposite surface of the RTB-based sintered magnet base material and dried.
  • An RTB-based sintered magnet having a paste coating film (dried film) formed on both sides was erected so that the coating surface was vertical. Specifically, after raising the temperature from room temperature to 400 ° C. at 10 ° C./min, heat treatment is performed at 400 ° C. for 2 hours, and further, the temperature is raised to 900 ° C. at 10 ° C./min, and then at 900 ° C. for 8 hours. The heat treatment was performed.
  • FIG. 5 is a graph showing the difference between the ratio of the mixed powder in Table 2 and the “residual C amount ⁇ mixed powder-containing C amount” in Table 3 for each type of binder and coupling agent. This figure shows that when the value of “residual C content ⁇ mixed powder content C content” is 0.07% by mass or more, there is no coating film peeling after heat treatment, and when it is less than 0.07% by mass, coating film peeling occurs. It is shown that. Regardless of the type of binder and coupling agent, “residual C amount—mixed powder-containing C amount” tends to decrease as the proportion of the mixed powder increases.
  • residual C amount—mixed powder-containing C amount varies depending on the type of binder or coupling agent and the blending ratio thereof. For example, when the ratio of the mixed powder is 98.78% by mass or 98.28% by mass, the same ratio of the mixed powder, that is, even when the same amount of the binder and the coupling agent is used, the binder and the coupling are used. Depending on the difference in the agent, peeling of the coating film may or may not occur.
  • the binder when the value indicated by ⁇ , the binder is ethyl cellulose and the coupling agent is an epoxy silane coupling agent, or the value indicated by ⁇ , the binder is PVA and the coupling agent is not present, the same resin Even if a coupling agent is used, "residual C amount-mixed powder-containing C amount" depending on the difference in the ratio of the mixed powder (that is, the difference in the amount of binder and coupling agent used) and the blending ratio of the binder and the coupling agent.
  • the coating film may or may not peel off. As can be seen from ⁇ and ⁇ (the binder is ethyl cellulose and no coupling agent), the presence or absence of the coupling agent is the same, and the coating film may or may not peel off with or without the coupling agent.
  • the presence or absence of peeling after the heat treatment is not determined by the ratio of the mixed powder, the type of the binder or the coupling agent, or the blending ratio, but the “residual C amount-mixed powder after the heat treatment determined by the combination thereof” It turns out that it depends on "the amount of contained C”.
  • the present invention has been completed based on such findings.
  • Example 2 The same evaluation as in Example 1 was performed using the mixed powder, binder, and coupling agent shown in Samples A to F in Table 5 below. The prepared paste was applied to a PET film and dried at 90 ° C. for 1 hour. Table 6 shows the ratio of each component in the dry film obtained by calculation.
  • the present invention can improve the H cJ of an RTB -based sintered magnet with less heavy rare earth element RH, and therefore can be used for the production of a rare-earth sintered magnet that requires a high H cJ .
  • the present invention can also be widely applied to techniques that require diffusion of metal elements other than the heavy rare earth element RH from the surface to the rare earth sintered magnet.
  • Metal powder particles Metal compound powder particles 100 RTB-based sintered magnet 200 Coating film

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  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
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Abstract

Un film de revêtement 200 d'une pâte qui contient un liant de résine 20 et une poudre mélangée obtenue par mélange d'une poudre métallique 22 et d'une poudre de composé métallique 24 est formé sur la surface d'un aimant fritté de système R-T-B 100. Après cela, le composant métallique dans le film de revêtement 200 est dispersé dans l'aimant fritté 100 par réalisation d'un traitement thermique. Le film de revêtement 200 contient du carbone qui reste après le traitement thermique, et la teneur en carbone dans le film de revêtement 200 avant le traitement thermique est ajustée de telle sorte que la valeur obtenue en soustrayant la teneur en carbone dans la poudre mélangée dans la pâte avant le traitement thermique de la teneur en carbone restant après le traitement thermique est à l'intérieur de la plage allant de 0,07 % en masse à 0,50 % en masse (inclus) de la totalité du film de revêtement 200 après le traitement thermique.
PCT/JP2016/071015 2015-07-29 2016-07-15 Procédé de fabrication d'aimant fritté de terres rares WO2017018252A1 (fr)

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JP2018164004A (ja) * 2017-03-27 2018-10-18 日立金属株式会社 Ｒ−ｔ−ｂ系焼結磁石の製造方法
JP2019062155A (ja) * 2017-09-28 2019-04-18 日立金属株式会社 Ｒ−ｔ−ｂ系焼結磁石の製造方法
JP2019075493A (ja) * 2017-10-18 2019-05-16 Tdk株式会社 磁石接合体
US20210296049A1 (en) * 2020-03-17 2021-09-23 Ningbo Jinji Strong Magnetic Material Co., Ltd. COATING MATERIALS FOR DIFFUSING INTO MAGNET OF NdFeB AND A METHOD OF MAKING IT
WO2023073228A1 (fr) 2021-10-29 2023-05-04 CureVac SE Arn circulaire amélioré pour exprimer des protéines thérapeutiques

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JP2018164004A (ja) * 2017-03-27 2018-10-18 日立金属株式会社 Ｒ−ｔ−ｂ系焼結磁石の製造方法
JP2019062155A (ja) * 2017-09-28 2019-04-18 日立金属株式会社 Ｒ−ｔ−ｂ系焼結磁石の製造方法
JP2019075493A (ja) * 2017-10-18 2019-05-16 Tdk株式会社 磁石接合体
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US20210296049A1 (en) * 2020-03-17 2021-09-23 Ningbo Jinji Strong Magnetic Material Co., Ltd. COATING MATERIALS FOR DIFFUSING INTO MAGNET OF NdFeB AND A METHOD OF MAKING IT
US11848152B2 (en) * 2020-03-17 2023-12-19 Ningbo Jinji Strong Magnetic Material Co., Ltd. Coating materials for diffusing into magnet of NdFeB and a method of making it
WO2023073228A1 (fr) 2021-10-29 2023-05-04 CureVac SE Arn circulaire amélioré pour exprimer des protéines thérapeutiques

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