EP0066348B1 - Verfahren zur Herstellung von Magneten - Google Patents

Verfahren zur Herstellung von Magneten Download PDF

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Publication number
EP0066348B1
EP0066348B1 EP19820300510 EP82300510A EP0066348B1 EP 0066348 B1 EP0066348 B1 EP 0066348B1 EP 19820300510 EP19820300510 EP 19820300510 EP 82300510 A EP82300510 A EP 82300510A EP 0066348 B1 EP0066348 B1 EP 0066348B1
Authority
EP
European Patent Office
Prior art keywords
particles
container
particle charge
pressing
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
Application number
EP19820300510
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English (en)
French (fr)
Other versions
EP0066348A2 (de
EP0066348A3 (en
Inventor
Kalatur Sabdam Vangipuram Lakshmi Narasimhan
Charles Daniel Preusch
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.)
Crucible Materials Corp
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Crucible Materials Corp
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Filing date
Publication date
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Publication of EP0066348A2 publication Critical patent/EP0066348A2/de
Publication of EP0066348A3 publication Critical patent/EP0066348A3/en
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Publication of EP0066348B1 publication Critical patent/EP0066348B1/de
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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
    • H01F1/06—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
    • 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
    • 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
    • H01F41/0273—Imparting anisotropy

Definitions

  • This invention relates to a method for producing magnets with improved remanence.
  • magnets from powdered magnetic alloys, including rare earth cobalt magnets, by compacting as by die pressing a charge of aligned or oriented fine powder of a magnetic alloy of the desired magnet composition. Thereafter, the compacted charge is heat treated at temperatures of the order of 1093 to 1143°C (2000 to 2090°F). It is known that by increasing the density in the production of magnets of this type from particle charges of the magnetic material that remanence can be improved. Conventionally, density is increased by raising the sintering temperature after die pressing; however, this results in a corresponding lowering of coercive force.
  • United State Patent Specification No. 3,919,003 discloses the alignment of particles of cobalt-rare earth alloy in a magnetic field prior to hydrostatic pressing to form a green bar, the green bar subsequently being sintered at about 1100°C to a density of 87% or more with substantially non-interconnecting pores.
  • Another object of the invention is in the production of magnets to provide for improved alignment or orientation to achieve higher remanence values.
  • the present invention provides a method for producing magnets with improved remanence by applying a magnetic field to a particle charge of a magnet alloy to magnetically align said particles, and thereafter consolidating said particle charge to form a magnet particle, wherein said method comprises hot isostatically pressing said particles to consolidate the same to full density.
  • said magnetic field is applied as at least one pulse, and suitably a plurality of pulses, with each said pulse having a duration not exceeding one second and a power level of at least 50,000 oersted (39789 ampere turns per centimetre).
  • the magnetically aligned particles are isostatically pressed to compact the particle charge in a hot condition.
  • hot as used herein in this context means a temperature below the full density sintering temperature of the particles but above the temperature necessary to produce a close-pore structure.
  • samarium to a temperature that is below the full density sintering temperature but above the temperature necessary to produce a close-pore structure and then subjects the material while at this temperature to isostatic compacting, increased density and thus improved remanence is achieved while maintaining good coercive force.
  • Coercive force is maintained by maintaining the temperature below the full density sintering temperature.
  • remanence is improved by aligning or orienting the material by the use of a pulsating magnetic field within a container.
  • the container may be a collapsible container within which the material can thereafter be isostatically compacted.
  • the pulsating magnetic field should have a pulse duration not exceeding one second per pulse and each pulse typically will be of the order of 15 millisecond.
  • At least one pulse and preferably two pulses at a power level of at least 50,000 Oe (39789 ampere turns per centimetre) is suitable for the purpose.
  • the particles may be compacted to an intermediate density by additional pulsing.
  • highly oriented SmC 05 magnets have been produced by the use of superconducting solenoids to generate the high-intensity magnetic fields.
  • These superconducting solenoids must be operated at cryogenic temperatures [-268°C (-450°F)] to pass the high-density current necessary to generate these high-intensity magnetic fields.
  • the required high-intensity magnetic fields are preferably produced by discharging an assemblage of capacitors, e.g. four hundred to one thousand capacitors, thereby eliminating the need for superconducting solenoids.
  • the container may be a rubber bag and preferably after alignment the bag is evacuated in the presence of a constant DC field which serves to maintain alignment.
  • the particles of magnet material may be aligned within a preformed container, which will be collapsible and of a material such as stainless steel.
  • the step of subjecting the aligned material to a steady DC field in an evacuated container has been found to "lock in” the alignment and thus ensure improved remanence.
  • SmC0 5 powder was oriented in a die cavity with an applied magnetic field and pressed, the applied field and the pressing direction being normal to each other.
  • the pressed powder after sintering and post sintering had the properties as set forth in Table I.
  • the sintered magnet was loosely wrapped with stainless steel foil (not pressure tight; for handling convenience only) and as-hot-isostatically pressed (HIPed) at 954°C (1750°F).
  • the as-HIPed magnet had the properties as set forth in Table I.
  • the HIPed magnet was reheat treated at 910°C (1670°F) for three hours and quenched.
  • the magnetic properties after HIPing and heat treatment are set forth in Table I.
  • Example 3 Using the powder from the same batch as in Example 3, a magnet was made by sintering SmC0 5 powder that was previously oriented and cold isostatically pressed. The magnet had the properties set forth in Table IV.
  • the theoretical maximum density is 8.6 gm/Cm 3 .
  • the specific magnet had a density of 8.31 g/Cm 3 before hot isostatic pressing and the density increase after hot isostatic pressing was only about 2%, which accounts for the small improvement in remanence reported in the example. It is anticipated that if the theoretical maximum density had been achieved during hot isostatic pressing about a 3% increase in remanence would result.
  • SmC0 5 alloy was loaded into a stainless container and hydrogen admitted into the container.
  • the pressure was built up to 30 atmospheres; hydrogen absorption by the alloy results in a disintegration of the alloy to about -80 mesh powder.
  • the dehydrided powder was jet milled to about 4 p particle size.
  • the fine powder was loaded into a rubber bag of 19.05 mm (3/4") diameter and the bag was contained in a stainless or plastics sheath.
  • the bag was then pressurized and the powder oriented by placing the rubber bag along with the sheath inside a coil, and pulsing the coil, at least three times, with enough power to generate 60,000 Oe (47746 ampere turns per centimetre) within the coil.
  • the oriented powder was then placed in a steady DC field of -10 kOe and the bag evacuated to lock the alignment.
  • the evacuated bag containing the powder was then placed in an isostatic press chamber and compressed with a pressure up to 7040 Kg/cm 2 (100,000 psi).
  • the green compact was subsequently sintered between 1000-1200°C and post sinter aged between 870 ⁇ 930°C.
  • the magnets prepared from these four batches of powder in the manner described above had the properties set forth in Table V, which Table also shows magnetic properties of conventional commercial magnets.
  • Powder of SmC0 5 was loaded in a rubber bag and oriented in the poles of an electromagnet in a field of 25 kOe.
  • the oriented powder was then evacuated maintaining the steady DC field.
  • the evacuated bag containing the oriented powder was isostatically pressed followed by sintering and heat treatment.
  • the magnet had the following properties as shown in Table VI.
  • a fourth batch of SmC0 5 was processed into magnets by procedures as described in Example 1 except for a change in the compaction method.
  • the powder contained in the bag after alignment was initially compacted inside the bad by placing the bag towards the end of the coil and employing the field gradient present in the coil during pulsing to bring forth an initial compaction to an intermediate density by additional pulsing.
  • the oriented compacted powder placed in a steady DC field was evacuated, isostatically pressed and sintered.
  • the sintered sample was of uniform diameter and had a flat top and bottom contrary to the samples prepared without the field gradient packing which had a pyramidal top.
  • the magnetic properties of the sintered magnet prepared as per this example are shown in Table VII.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Manufacturing Cores, Coils, And Magnets (AREA)
  • Hard Magnetic Materials (AREA)
  • Powder Metallurgy (AREA)

Claims (14)

1. Verfahren zur Herstellen von Magneten mit erhöhter Remanenz durch Anlegen eines magnetischen Feldes an eine Teilchenfüllung aus Magnetlegierung um die Teilchen magnetisch auszurichten, wonach die Teilchenfüllung verfestigt wird um einen Magnetkörper zu bilden, dadurch gekennzeichnet, daß das Verfahren den Schritt des heißen isostatischen Pressens der Teilchen aufweist um diese zur vollen Dichte zu verfestigen.
2. Verfahren nach Anspruch 1, bei dem vor dem heißen isostatischen Pressen die Teilchenfüllung auf eine Temperatur aufgeheizt wird, die unterhalb der zur vollen Dichte erforderlichen Sintertemperatur ist, aber oberhalb derjenigen Temperatur ist, bei der die Teilchenfüllung im wesentlichen gasdicht ist.
3. Verfahren nach Ansprüchen 1 oder 2, bei dem die ausgerichtete Füllung zuerst bei Raumtemperatur durch Druckpressen oder kalte isostatische Komprimierung verdichtet wird, bevor sie erwärmt oder durch heißes isostatisches Pressen endverdichtet wird.
4. Verfahren nach einem der vorhergehenden Ansprüche, bei dem das magnetische Feld in Form von wenigstens einem Impuls angelegt wird, wobei jeder Impuls eine Dauer aufweist, die eine Sekunde nicht überschreitet und eine Stärke von wenigstens 50.000 Oersted (39789 Ampere-Windungen pro Zentimeter) aufweist.
5. Verfahren nach Anspruch 4, bei dem das magnetische Feld in Form einer Vielzahl von Impulsen angelegt wird, wobei jeder Impuls eine dauer aufweist, die eine Sekunde nicht überschreitet und eine Stärke von wenigstens 50.000 Oersted (39789 Ampere-Windungen pro Zentimeter) aufweist.
6. Verfahren nach einem der vorhergehenden Ansprüche, bei dem das magnetische Feld an die Teilchenfüllung innerhalb eines Behälters angelegt wird.
7. Verfahren nach Anspruch 6, bei dem die Teilchen in einem zusammenklappbaren Behälter zum magnetsichen Ausrichten und anschließender Verdichtung eingegeben werden.
8. Verfahren nach Anspruch 7, bei dem der Behälter ein Gummibehälter ist.
9. Verfahren nach Ansprüchen 6, 7 und 8, bei dem der Behälter so vorgeformt ist, daß er der gewünschten Gestalt der Teilchenfüllung nach der Verfestigung entspricht.
10. Verfahren nach einem der Ansprüche 6 bis 9, bei dem der Behälter in Gegenwart eines elektrischen Gleichstromfeldes nach dem Ausrichten der Teilchen evakuiert wird.
11. Verfahren nach einem der vorhergehenden Ansprüche, bei dem die Magnetlegierung wenigstens ein Übergangselement und wenigstens ein Seltene Erde-Element aufweist.
12. Verfahren nach Anspruch 11, bei dem wenigstens eines der Übergangselemente Kobalt ist.
13. Verfahren nach Ansprüche 11 oder 12, bei dem wenigstens eines der Seltene Erde-Elemente Samarium ist.
14. Verfahren nach einem der vorhergehenden Ansprüche, bei dem nach dem magnetischen Ausrichten der Teilchen diese Teilchen zu einer mittleren Dichte durch zusätzliche Impulse verdichtet werden.
EP19820300510 1981-05-11 1982-02-01 Verfahren zur Herstellung von Magneten Expired EP0066348B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US26227081A 1981-05-11 1981-05-11
US262270 1981-05-11

Publications (3)

Publication Number Publication Date
EP0066348A2 EP0066348A2 (de) 1982-12-08
EP0066348A3 EP0066348A3 (en) 1983-03-30
EP0066348B1 true EP0066348B1 (de) 1985-10-09

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Family Applications (1)

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EP19820300510 Expired EP0066348B1 (de) 1981-05-11 1982-02-01 Verfahren zur Herstellung von Magneten

Country Status (4)

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EP (1) EP0066348B1 (de)
JP (1) JPS57194512A (de)
CA (1) CA1176814A (de)
DE (1) DE3266728D1 (de)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1216623A (en) * 1983-05-09 1987-01-13 John J. Croat Bonded rare earth-iron magnets
US5080731A (en) * 1988-08-19 1992-01-14 Hitachi Metals, Ltd. Highly oriented permanent magnet and process for producing the same
JP3554604B2 (ja) * 1995-04-18 2004-08-18 インターメタリックス株式会社 圧粉体成形方法及び該方法に使用するゴムモールド
JP6511069B2 (ja) 2014-03-31 2019-05-15 エーエスエムエル ネザーランズ ビー．ブイ． アンジュレータ

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3919003A (en) * 1971-12-17 1975-11-11 Gen Electric Sintered cobalt-rare earth intermetallic product
JPS5646245B2 (de) * 1973-06-23 1981-10-31
CH603802A5 (de) * 1975-12-02 1978-08-31 Bbc Brown Boveri & Cie
JPS52155124A (en) * 1976-06-18 1977-12-23 Hitachi Metals Ltd Permanent magnetic alloy
JPS5941840B2 (ja) * 1978-12-28 1984-10-09 株式会社井上ジャパックス研究所 磁場プレス装置
JPS5923446B2 (ja) * 1979-03-22 1984-06-02 ティーディーケイ株式会社 プラスチック磁石とその製造法

Also Published As

Publication number Publication date
JPH0318329B2 (de) 1991-03-12
DE3266728D1 (en) 1985-11-14
CA1176814A (en) 1984-10-30
JPS57194512A (en) 1982-11-30
EP0066348A2 (de) 1982-12-08
EP0066348A3 (en) 1983-03-30

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