EP0583041B1 - Verfahren zum Herstellen eines Dauermagneten auf Basis von NdFeB - Google Patents

Verfahren zum Herstellen eines Dauermagneten auf Basis von NdFeB Download PDF

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Publication number
EP0583041B1
EP0583041B1 EP93202359A EP93202359A EP0583041B1 EP 0583041 B1 EP0583041 B1 EP 0583041B1 EP 93202359 A EP93202359 A EP 93202359A EP 93202359 A EP93202359 A EP 93202359A EP 0583041 B1 EP0583041 B1 EP 0583041B1
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EP
European Patent Office
Prior art keywords
powder
ndfeb
alloy
magnet
average particle
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP93202359A
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English (en)
French (fr)
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EP0583041A1 (de
Inventor
Kurt Heinz Jürgen Buschow
Franciscus Hubertus Feijen
Dirk Bastiaan De Mooij
Arjan Noordermeer
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Koninklijke Philips NV
Original Assignee
Koninklijke Philips Electronics NV
Philips Electronics NV
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Publication date
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Priority to EP93202359A priority Critical patent/EP0583041B1/de
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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
    • H01F1/055—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
    • 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
    • B22F1/09—Mixtures of metallic powders

Definitions

  • the invention relates to a method of manufacturing a permanent magnet on the basis of NdFeB, in which method a powder of NdFeB and a powder of metallic Ga are mixed to form a mixture which is subsequently aligned and compressed into a shaped article which is then sintered.
  • Magnets on the basis of NdFeB have extremely favourable hard-magnetic properties, such as a large energy product and a relatively high saturation magnetization. Said magnets are used, in particular, in applications requiring miniaturization of hard-magnetic components, as is the case with, for example, small electric motors for driving hard discs in computers.
  • a method of the type mentioned in the opening paragraph is described in, for example, European Patent Application EP-A 249.973.
  • a powder of an intermetallic alloy of composition Nd 13 Fe 81 B 6 is mixed with a powder of metallic Ga in a ball mill.
  • the mixture thus obtained comprises 96 wt.% of NdFeB powder having an average particle size of 3 micrometers and 4 wt.% of metallic Ga powder having an average particle size of a few tens of micrometers.
  • the mixture is subsequently aligned in a magnetic field, compressed under increased pressure at 600° C and sintered.
  • This method causes Ga to melt and subsequently form a so-called cementing phase which is present between the magnetic grains of the NdFeB.
  • the presence of said Ga-containing phase around the NdFeB grains provides the magnet with an improved corrosion resistance and an increased coercive force.
  • the known method has disadvantages.
  • metallic Ga is very ductile by nature. Owing thereto it proved to be very difficult to convert metallic Ga into homogenic powders. This applies in particular to Ga powders having an average grain size below 100 micrometers. Ga powders having an average grain size below 10 micrometers cannot be produced in practice. It has been found that mixing such Ga powders and NdFeB powders to a homogeneous mixture is a very problematic process. If said powders are inhomogeneously mixed, the magnetic properties of the permanent magnets are adversely affected.
  • the invention further aims at providing a method of manufacturing permanent magnets having a relatively satisfactory corrosion resistance and a relatively large coercive force.
  • the magnets manufactured in accordance with the inventive method must also exhibit a sufficiently high Curie temperature.
  • a method as described in the opening paragraph which is characterized according to the invention in that instead of a powder of metallic Ga a powder of a Ga alloy is used which predominantly comprises Ga and one or more than one rare earth metals (RE). It has been found that alloys of Ga and one or more than one rare earth metals are very brittle. By virtue thereof they can be pulverized relatively easily into powders having a relatively small average grain size. Homogenic powders having an average grain size of 10 micrometers and less can be manufactured in a relatively simple manner from RE-Ga alloys. In this respect, alloys of NdGa and NdPrGa were found to be suitable.
  • RE rare earth metals
  • the Ga of the alloy can make a bond with the free Nd, which is present in relatively large quantities in the liquid phase, to form an alloy which is not sensitive to oxidation. Further it has been found that, during sintering, an exchange of Ga for Fe, which is bonded in the hard-magnetic phase of the grains, can take place. Said exchange, which occurs in the outermost part of the grains, provides the hard-magnetic material with an increased Curie temperature.
  • a further preferred embodiment of the method in accordance with the invention is characterized in that the rare earth metals used are Tb and/or Dy. Alloys of these elements with Ga do not only provide the magnets with an increased Curie temperature and an improved resistance to corrosion but also with an increased anisotropy. This can probably be attributed to an exchange of Nd for Tb and/or Dy in the outermost part of the magnetic grains. The Nd thus released in the liquid phase is bonded by the Ga present to form an alloy which is not sensitive to oxidation.
  • a further favourable embodiment of the method in accordance with the invention is characterized in that the average particle size of the powder of the Ga alloy is smaller than the average particle size of the powder of NdFeB.
  • the average particle size of the powder of the Ga alloy ranges from 2-10 micrometers and the average particle size of the NdFeB powder ranges from 10-100 micrometers.
  • Fig. 1 shows the magnetization curve measured after cooling of the sintered magnet.
  • Said magnet exhibited a magnetization of 118 Am 2 /kg and a coercive force of 300 kA/m.
  • the Curie temperature of the magnet was 322° C. This is seven degrees higher than the Curie temperature of a magnet to which no DyGa powder was added. Accelerated life tests showed that the magnet had a better resistance to oxidation than a conventional NdFeB magnet.
  • a powder having an average particle size of 10 micrometers, formed from the above-mentioned NdFeB alloy was mixed in the same manner with a DyGa powder having an average particle size of 5 micrometers.
  • the quantity of GaDy powder being 3 wt.% of the overall mixture.
  • This mixture was subsequently oriented, compressed and sintered (1 hour, 1048° C). After sintering the magnet was subjected to a temperature treatment at 580° C under a protective gas for 90 minutes.
  • Fig. 2 shows the magnetization curve of the magnet described in the preceding paragraph.
  • the magnetization was 117 kA 2 /kg and the coercive force was 1300 kA/m.
  • the Curie temperature was 322° C. Also this magnet was found to be less sensitive to oxidation than conventional NdFeB magnets which do not comprise Ga in the intergranular phase.

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  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Hard Magnetic Materials (AREA)
  • Powder Metallurgy (AREA)

Claims (5)

  1. Verfahren zum Herstellen eines Dauermagneten auf Basis von NdFeB, wobei ein Pulver von NdFeB und ein Pulver von metallischem Ga zu einem Gemisch verarbeitet werden, das daraufhin ausgerichtet und zu einem Formteil zusammengepreßt und danach gesintert wird, dadurch gekennzeichnet, daß statt eines Pulvers von metallischem Ga ein Pulver einer Ga-Legierung verwendet wird, das vorwiegend aus einem oder mehreren Seltenerdmetallen (RE) besteht.
  2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Zusammensetzung der Legierung der Formel REGax entspricht, wobei x=1 oder x=2 ist.
  3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die verwendeten Seltenerdmetalle Dy und/oder Tb sind.
  4. Verfahren nach Anspruch 1, 2 oder 3, dadurch gekennzeichnet, daß die mittlere Teilchengröße des Pulvers der Ga-Legierung kleiner ist als die mittlere Teilchengröße des Pulvers von NdFeB.
  5. Verfahren nach Anspruch 1, 2, 3 oder 4, dadurch gekennzeichnet, daß das Gemisch 1 - 5 Gew.%, vorzugsweise 2 - 4 Gew.% des Pulvers der Ga-Legierung enthält.
EP93202359A 1992-08-13 1993-08-11 Verfahren zum Herstellen eines Dauermagneten auf Basis von NdFeB Expired - Lifetime EP0583041B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP93202359A EP0583041B1 (de) 1992-08-13 1993-08-11 Verfahren zum Herstellen eines Dauermagneten auf Basis von NdFeB

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP92202498 1992-08-13
EP92202498 1992-08-13
EP93202359A EP0583041B1 (de) 1992-08-13 1993-08-11 Verfahren zum Herstellen eines Dauermagneten auf Basis von NdFeB

Publications (2)

Publication Number Publication Date
EP0583041A1 EP0583041A1 (de) 1994-02-16
EP0583041B1 true EP0583041B1 (de) 1997-02-05

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4044202A1 (de) * 2021-01-15 2022-08-17 Yantai Shougang Magnetic Materials Inc. Verfahren zur herstellung eines gesinterten ndfeb-magneten mit hoher koerzitivfeldstärke

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19636284C2 (de) * 1996-09-06 1998-07-16 Vacuumschmelze Gmbh SE-Fe-B-Dauermagnet und Verfahren zu seiner Herstellung
DE19636283A1 (de) * 1996-09-06 1998-03-12 Vacuumschmelze Gmbh Verfahren zur Herstellung eines SE-FE-B-Dauermagneten
CN106735202B (zh) * 2016-12-05 2018-06-19 江西理工大学 一种石墨烯改性烧结钕铁硼永磁材料及其制备方法

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3774333D1 (de) * 1986-06-16 1991-12-12 Tokin Corp Dauermagnet-material und verfahren zur herstellung.
JP2675430B2 (ja) * 1989-10-12 1997-11-12 川崎製鉄株式会社 耐蝕性希土類―遷移金属系磁石およびその製造方法

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4044202A1 (de) * 2021-01-15 2022-08-17 Yantai Shougang Magnetic Materials Inc. Verfahren zur herstellung eines gesinterten ndfeb-magneten mit hoher koerzitivfeldstärke
US11854736B2 (en) * 2021-01-15 2023-12-26 Yantai Dongxing Magnetic Materials Inc. Method of preparing a high-coercivity sintered NdFeB magnet

Also Published As

Publication number Publication date
EP0583041A1 (de) 1994-02-16

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