EP0386286B1 - Auf Seltenerdeisen basierender Dauermagnet - Google Patents

Auf Seltenerdeisen basierender Dauermagnet Download PDF

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Publication number
EP0386286B1
EP0386286B1 EP89104002A EP89104002A EP0386286B1 EP 0386286 B1 EP0386286 B1 EP 0386286B1 EP 89104002 A EP89104002 A EP 89104002A EP 89104002 A EP89104002 A EP 89104002A EP 0386286 B1 EP0386286 B1 EP 0386286B1
Authority
EP
European Patent Office
Prior art keywords
rare earth
permanent magnet
iron
cobalt
magnet
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
EP89104002A
Other languages
English (en)
French (fr)
Other versions
EP0386286A1 (de
Inventor
Ken Ohashi
Yoshio Tawara
Toshikazu Yokoyama
Ryo Osugi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shin Etsu Chemical Co Ltd
Original Assignee
Shin Etsu Chemical Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from JP62233481A external-priority patent/JPS6476703A/ja
Application filed by Shin Etsu Chemical Co Ltd filed Critical Shin Etsu Chemical Co Ltd
Priority to DE1989624587 priority Critical patent/DE68924587T2/de
Priority to EP89104002A priority patent/EP0386286B1/de
Publication of EP0386286A1 publication Critical patent/EP0386286A1/de
Application granted granted Critical
Publication of EP0386286B1 publication Critical patent/EP0386286B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • 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
    • H01F1/0555—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 pressed, sintered or bonded together
    • H01F1/0557—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 pressed, sintered or bonded together sintered

Definitions

  • the present invention relates to a rare earth-based permanent magnet alloy or, more particularly, to a rare earth-based alloy for permanent magnet having excellent magnetic properties and useful as a component of various kinds of electric and electronic instruments.
  • Ternary alloys of neodymium, boron and iron have been proposed in recent years as a material of permanent magnets having magnetic properties even higher than those of smarium-cobalt magnets (see, for example, Japanese Patent Kokai 59-46008) and greatly highlighted in respect of the abundance of the naturally occurring resources of neodymium and iron as compared with samarium and cobalt.
  • this ternary magnet alloy has a serious defect of high susceptibility to rusting so that no practically usable permanent magnet can be prepared from the alloy unless the permanent magnet is provided with a protective coating layer against rusting.
  • No industrially applicable coating method for protective coating has yet been developed and this problem is a bottleneck which prevents the permanent magnets of this type from prevalence.
  • permanent magnets of the ternary alloy of neodymium, iron and boron have a relatively low Curie point T c of 310 °C and the residual magnetization thereof has a large temperature dependency of -0.12%/°C so that they can hardly be used in the field of applications in which stability of the magnetic properties is essential against variation of the temperature as in electric motors and measuring instruments.
  • Extensive investigations are of course now under way to develop rare earth-based permanent magnet alloys other than the above mentioned one such as an alloy composed of a rare earth element R and a transition metal M of which the ratio of R:M is 10 or larger and ternary alloys other than R2Fe14B but no promising magnet alloys have yet been discovered.
  • binary intermetallic compounds composed of a rare earth element R and iron are well known as a magnetic material including RFe2, RFe3 and R2Fe17.
  • Tey are, however, not satisfactory as a material of permanent magnets because each of them has a disadvantageously low value of either one of the important magnetic properties such as the Curie point T c , saturation magnetization M S and magnetic anisotropy coefficient K u .
  • Croat et al. have reported in Appl. Phys. Lett., volume 37, page 1096 (1981) that a permanent magnet of a rare earth-iron binary system can be obtained by undertaking the method of thin-film quenching method in which a metastable phase is quenched and immobilized.
  • the above described binary intermetallic compounds are each in a metastable phase produced by the method of sputtering in the form of a thin film of which the crystalline structure is hexagonal according to the report of the authors. It is generally understood that these binary intermetallic compounds cannot provide a permanent magnet in a bulky form. Such a magnet is magnetically isotropic with consequently low magnetic properties and the stability thereof is also questionable as an attribute of the metastable phase forming the basic structure of the magnet. Accordingly, it is eagerly desired to develop a rare earth-based alloy for permanent magnets having high magnetic properties with stability and rustproofness from inexpensive materials.
  • EP-A 0 253 428 teaches a magnetic material having a tetragonal crystal structure of the ThMn12-type whereby said magnetic material has the formula Re(Me I 1-x Me II x )12 wherein Re is one or more rare earth metals, Me I is Fe, Co or a mixture of Fe and Co, Me II is Ti, V, Cr, Si, W or Mo, and x represents 0,1 to 0,35.
  • EP-A 0 106 948 teaches magnetic materials comprising Fe, B, R (rare earth elements) and Co having a major phase of Fe-Co-B-R intermetallic compound(s) of tetragonal system. There it is also taught that the substitution of Fe with Co generally causes complicated results which are almost unexpectable.
  • the rare earth element denoted by R in the above and useful as an ingredient of the inventive magnet include yttrium and the elements having an atomic number of 57 to 71, i.e. lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium.
  • the rare earth element is yttrium or a so-called light rare earth element having an atomic number of, for example, 57 to 64.
  • Heavy rare earth elements are less preferable because of the possible decrease in the saturation magnetization M s of the magnet prepared therefrom. It is of course optional that two kinds or more of the rare earth elements are used in combination, if so desired.
  • the balance of the rare earth element and titanium is iron and an unavoidable amount of impurities including carbon, oxygen and the like.
  • the permanent magnet of the invention can be prepared by the well known powder metallurgical method. Namely, the rare earth element, titanium and iron each in the metallic from are melted together and cast in a mold and the powder of the compound obtained by pulverizing the ingot is molded in a magnetic field into a powder compact or green body which is sintered and aged according to a schedule of the heat treatment in such a manner that the crystalline grains in the resultant magnet have a particle diameter not ex-ceeding 25 ⁇ m or, preferably, in the range from 5 to 15 ⁇ m.
  • the magnetic compound of the invention is further admixed with a transition element and a light element such as aluminum and silicon with an object to further improve the magnetic properties or, in particular, coercive force i H c although, in most cases, the saturation magnetization M s is more or less decreased thereby so that it is important when addition of such elements is intended to consider the balance of the coercive force and the saturation magnetization in the selection of the kind and amount of the additive elements.
  • the most disadvantageous defect in the neodymium-iron-boron magnets is the high susceptibility of the ternary compound to oxidation and a great decrease is caused in the magnetic properties of the magnets prepared by the powder metallurgical method due to the rapid oxidation of the surface of the fine particles thereof in the course of the magnet preparation.
  • a magnet prepared thereby is also susceptible to rusting and cannot be used in a practical application unless a protective surface coating is provided thereon.
  • the rare earth-based permanent magnet of the invention is highly corrosion-resistant despite the high content of iron and can be used as such without a protective surface coating although the corrosion resistance can be further enhanced when the magnet is provided with a surface coating by spraying or electrodeposition of a resinous coating composition or by vapor-phase deposition, sputtering or ion plating of a highly corrosion-resistant metallic material.
  • the quenching thin-film method is also applicable to the inventive permanent magnet to give a thin-film magnet having a high coercive force which is pulverized and processed into an isotropic plastic magnet according to a known procedure. It is of course possible that an anisotropically sintered magnet is pulverized and the powder is processed into a magnetically anisotropic plastic magnet.
  • a ternary magnetic compound of a rare earth element, titanium and iron of the formula RTiFe11 has an outstandingly high Curie point as compared with the R2Fe17-type binary magnetic compounds.
  • a magnet of SmTiFe11 has a Curie point of about 310 °C.
  • the improvement obtained by the above described ternary magnetic compound of a rare earth element, titanium and iron is still insufficient in respect of the relatively large temperature dependency of the magnetic properties as in the neodymium-iron-boron magnets.
  • the magnetic compound or alloy, respectively, of the inventive permanent magnet consists essentially of (a) from 12% to 30% by weight of a rare earth element or a combination of two kinds or more of rare earth elements, (b) from 1% to 10% by weight of titanium, (c) up to 34% by weight or, preferably, up to 27% by weight of cobalt and (d) the balance of iron, the principal crystalline phase of the compound belonging to the body-centered tetragonal system of the ThMn12 type.
  • the amount of cobalt should appropriately be selected depending on the desired degree of improvement in the Curie point. It should be noted, however, increase in the content of cobalt over the above mentioned upper limit has no particularly advantageous effect in further increasing the Curie point rather with disadvantageous influences on other magnetic properties if not to mention the increased cost due to the use of a large amount of the expensive cobalt metal. Generally speaking, a cobalt content of 10% by weight has an effect of increasing the Curie point of the magnet by about 90 °C or more along with a remarkable effect in decreasing the temperature dependency of the magnetic properties.
  • Each of the ingots was crushed and pulverized in a jet mill using nitrogen gas as the jet gas into a fine powder having an average particle diameter of 2 to 10 ⁇ m.
  • the powder in a mold was magnetically oriented in a magnetic field of 1,19 x 106 A/m (15 kOe) and shaped by press-molding in a hydraulic press under a pressure of 1.5 tons/cm2 into a powder compact which was sintered for 1 hour in an atmosphere of argon gas at a temperature of 1000 to 1200 °C and subjected to an aging treatment for 1 hour at 400 to 900 °C followed by quenching.

Claims (3)

  1. Permanentmagnet auf Basis einer Legierung, die im wesentlichen besteht aus
    (a) 12 bis 30 Gew.-% mindestens eines Seltenerdelementes ausgewählt aus der Gruppe bestehend aus Yttrium und den Elementen mit den Atomzahlen 57 bis 71,
    (b) 1 bis 10 Gew.-% Titan,
    (c) bis zu 34 Gew.-% Kobalt mit Ausnahme von 0 % und
    (d) Eisen als Rest,
    wobei die Hauptphase der Legierung eine kristalline Struktur besitzt, die zu dem raumzentrierten tetragonalen System vom ThMn₁₂-Typ gehört, und der Volumenanteil dieser Phase mindestens 50 % ausmacht.
  2. Permanentmagnet nach Anspruch 1, bei dem das Seltenerdelement ausgewählt ist aus der Gruppe bestehend aus Yttrium und den Elementen mit einer Atomzahl von 57 bis 64.
  3. Permanentmagnet nach Anspruch 1, bei dem die Menge an Kobalt als Komponente (c) nicht mehr als 27 Gew.-% ausmacht.
EP89104002A 1987-09-17 1989-03-07 Auf Seltenerdeisen basierender Dauermagnet Expired - Lifetime EP0386286B1 (de)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE1989624587 DE68924587T2 (de) 1989-03-07 1989-03-07 Auf Seltenerdeisen basierender Dauermagnet.
EP89104002A EP0386286B1 (de) 1987-09-17 1989-03-07 Auf Seltenerdeisen basierender Dauermagnet

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP62233481A JPS6476703A (en) 1987-09-17 1987-09-17 Rare earth element permanent magnet
EP89104002A EP0386286B1 (de) 1987-09-17 1989-03-07 Auf Seltenerdeisen basierender Dauermagnet

Publications (2)

Publication Number Publication Date
EP0386286A1 EP0386286A1 (de) 1990-09-12
EP0386286B1 true EP0386286B1 (de) 1995-10-18

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EP89104002A Expired - Lifetime EP0386286B1 (de) 1987-09-17 1989-03-07 Auf Seltenerdeisen basierender Dauermagnet

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Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3751084B2 (ja) * 1996-08-30 2006-03-01 本田技研工業株式会社 複合磁歪材料およびその製造方法
DE102013009940A1 (de) * 2013-06-13 2014-12-18 Hochschule Aalen Magnetisches Material, seine Verwendung und Verfahren zu dessen Herstellung
CN107785140A (zh) * 2016-08-24 2018-03-09 株式会社东芝 磁铁材料、永久磁铁、旋转电机及车辆
EP3291250B1 (de) * 2016-08-24 2021-05-26 Kabushiki Kaisha Toshiba Magnetmaterial, dauermagnet, elektrische rotationsmaschine und fahrzeug
US10490325B2 (en) 2016-08-24 2019-11-26 Kabushiki Kaisha Toshiba Magnetic material, permanent magnet, rotary electrical machine, and vehicle
CN107785139A (zh) * 2016-08-24 2018-03-09 株式会社东芝 磁铁材料、永久磁铁、旋转电机及车辆
JP6614365B2 (ja) * 2016-12-26 2019-12-04 日立金属株式会社 希土類−遷移金属系強磁性合金
JP6995542B2 (ja) * 2017-09-19 2022-02-04 株式会社東芝 磁石材料、永久磁石、回転電機、及び車両
WO2019058588A1 (en) * 2017-09-20 2019-03-28 Kabushiki Kaisha Toshiba MAGNETIC MATERIAL, PERMANENT MAGNET, ROTATING ELECTRIC MACHINE AND VEHICLE

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0106948A2 (de) * 1982-09-27 1984-05-02 Sumitomo Special Metals Co., Ltd. Permanent magnetisierbare Legierungen, magnetische Materialien und Dauermagnete die FeBR oder (Fe,Co)BR (R=seltene Erden) enthalten

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0242283B1 (de) * 1986-04-12 1990-11-07 Shin-Etsu Chemical Co., Ltd. Legierung auf Basis seltener Erden für Permanentmagnet
US5041171A (en) * 1986-07-18 1991-08-20 U.S. Philips Corporation Hard magnetic material

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0106948A2 (de) * 1982-09-27 1984-05-02 Sumitomo Special Metals Co., Ltd. Permanent magnetisierbare Legierungen, magnetische Materialien und Dauermagnete die FeBR oder (Fe,Co)BR (R=seltene Erden) enthalten

Also Published As

Publication number Publication date
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