EP1032940A1 - Method for producing a magnetic alloy powder - Google Patents

Method for producing a magnetic alloy powder

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Publication number
EP1032940A1
EP1032940A1 EP98956933A EP98956933A EP1032940A1 EP 1032940 A1 EP1032940 A1 EP 1032940A1 EP 98956933 A EP98956933 A EP 98956933A EP 98956933 A EP98956933 A EP 98956933A EP 1032940 A1 EP1032940 A1 EP 1032940A1
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EP
European Patent Office
Prior art keywords
alloy
powder
mpa
hydrogen
range
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.)
Granted
Application number
EP98956933A
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German (de)
French (fr)
Other versions
EP1032940B1 (en
Inventor
Oliver Gutfleisch
Michael Kubis
Axel Handstein
Bernhard Gebel
Karl-Hartmut MÜLLER
Ivor Rex Harris
Ludwig Schultz
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Institut fuer Festkoerper und Werkstofforschung Dresden eV
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Institut fuer Festkoerper und Werkstofforschung Dresden eV
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Priority claimed from DE1997151366 external-priority patent/DE19751366C2/en
Priority claimed from DE19751367A external-priority patent/DE19751367C2/en
Application filed by Institut fuer Festkoerper und Werkstofforschung Dresden eV filed Critical Institut fuer Festkoerper und Werkstofforschung Dresden eV
Publication of EP1032940A1 publication Critical patent/EP1032940A1/en
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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
    • H01F1/0553—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 obtained by reduction or by hydrogen decrepitation or embrittlement
    • 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
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/023—Hydrogen absorption
    • 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
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy

Definitions

  • the invention relates to the field of metallurgical process engineering and relates to a method for producing a magnetic alloy powder for hard magnetic applications.
  • the powder consists of a samanum-cobalt-based alloy.
  • the powder can be used to produce highly coercive permanent magnets by hot compaction or plastic binding. With the powder, however, such permanent magnets can also be produced by powder sintering by sintering.
  • Sm-Co-based permanent magnets have so far mainly been produced by powder metallurgy by sintering
  • CONFIRMATION HEADS Set microstructure that enables a high coercive force through the pinmng mechanism. However, these additives reduce the saturation magnetization.
  • the HD process (hydride decrepitation) has long been known in the field of the manufacture of magnetic powders based on alloys with elements from the rare earth element group (SE) (US Pat. No. 5,580,396, column 8, lines 30 to 41; Rare-earth Iron Permanent Magnets, ed.JMD Coey, Oxford 1996, pages 346 to 349 and pages 370 to 380).
  • SE rare earth element group
  • This process is used for crushing coarse, compact alloy bodies, and is therefore used for powder production.
  • the effect is used here that the hydrogen diffused into the intermediate grain phase or onto the intermediate lattice sites of the SE compound leads to an expansion of the intermediate grain phase or to a lattice extension of the SE compound.
  • HDDR hydrogenation-disproportionation-desorption-
  • This chemical reaction can be represented schematically (using the model substance A x B y mentioned above) as follows:
  • the hydrogenated alloy elements are then dehydrated again in a second process stage by means of a heat treatment under vacuum conditions, with simultaneous recombination of the alloy composition decomposed in stage 1 according to the following reaction equation:
  • HDDR stage 1 heating up to the temperatures of 500 ° C to 1000 ° C necessary for the above-described reaction often results in the hydrogen absorption typical of the HD process, as described above in the equation for the HD process is described, however, this is only an intermediate reaction, which is immediately followed by the desorption of the hydrogen.
  • the HDDR treatment can be carried out completely independently of the HD process, as has been shown, for example, with the “sol-HDDR” process, in which the hydrogen gas only reaches the peactor at the temperature m required for disproportionation (HDDR stage 1) is admitted and so there is no interstitial absorption of the hydrogen and thus no HD process (Gutyak et al., J. Alloys Compd. 215 (1994) 227).
  • the invention has for its object to provide a method which enables a technologically controllable and inexpensive production of a hard magnetic powder consisting of a samarium-cobalt-base alloy for highly coercive permanent magnets.
  • the process is based on an HDDR treatment in which a starting powder is subjected to hydrogenation with disproportionation of the alloy in a first process step under hydrogen and in a subsequent second process step to hydrogen desorption with recombination of the alloy under vacuum conditions.
  • a starting powder containing samarium and cobalt is used in the first process stage either at a high temperature in the range from 500 ° C. to 900 ° C. and with a high hydrogen pressure of> 0.5 MPa or using intensive fine grinding at a low temperature in the range from 50 ° C to 500 ° C and treated with a hydrogen pressure of> 0.15 MPa.
  • a hydrogen pressure in the range of 1.0 MPa to 5.0 MPa is preferably applied.
  • the intensive fine grinding is carried out for a period of 1 h to 100 h.
  • a starting powder can be a powder of an Sm-Co-based alloy or a powder mixture consisting of the individual elements of an S-Co-based alloy and / or consisting of one or more, for use in the case of intensive fine grinding a Sm-Co-based alloy suitable master alloys are used.
  • the starting powder should preferably be finely ground at a hydrogen pressure in the range from 0.5 MPa to 2.5 MPa.
  • the hydrogen desorption treatment is expediently carried out on the magnetic powder obtained by means of a heat treatment in the range from 500 ° C. to 1000 ° C.
  • starting powders which form magnetic alloy powders having the alloy composition Sm x Co ⁇ oo- x with 10 ⁇ x ⁇ 30 or the alloy composition Sm x C ⁇ oo- x - a - b - c Fe a CU b Zr c with 10 ⁇ x ⁇ 30, a ⁇ 45, b ⁇ 15 and c ⁇ 15.
  • the method according to the invention creates a new possibility for the magnetic hardening of Sm-Co base compounds.
  • the method opens up new approaches for optimizing the magnetic properties of Sm-Co magnets, which leads to an improvement in the properties and represents an inexpensive alternative for the production of such magnets.
  • a melted Sm 2 (Co, Fe, Cu, Zr) ⁇ 7 starting alloy as is usually used for the production of S-Co sintered magnets and whose coercive strengths are determined by the pinmng mechanism, is crushed down to particle sizes ⁇ 160 ⁇ and then heated in a hydrogen atmosphere of 2 MPa to a temperature of 600 ° C. and held at this temperature for half an hour.
  • the powder is hydrogenated by the hydrogen, with a disproportionation of the alloy taking place.
  • the powder is then heated to 750 ° C. with constant pumping and is held at this temperature again for half an hour.
  • the powder produced in this way has a high coercive force H c of about 5 kA / cm and can be processed into powerful permanent magnets.
  • An SmCos base alloy is crushed to particle sizes ⁇ 500 ⁇ m and then heated in a hydrogen atmosphere of 2 MPa to a temperature of 600 ° C and held at this temperature for half an hour. Then the powder is under constant Pumping heated up to 750 ° C and held again at this temperature for half an hour.
  • the powder produced in this way has a high coercive force H c of about 10 kA / cm and can be used for the production of powerful permanent magnets.
  • a melted Sm 2 (Co, Fe, Cu, Zr) 17 starting alloy is crushed down to particle sizes smaller than 160 ⁇ m and then, using a vibratory mill in a hydrogen atmosphere of 1 MPa, at a grinding bowl temperature of 350 ° C., intensively ground for a period of 20 hours. In addition to fine grinding, a disproportionation of the alloy takes place simultaneously due to the hydrogen present.
  • the powder is then heated to 750 ° C. while hydrogen is being pumped out, and is held at this temperature for half an hour in order to carry out hydrogen desorption.
  • the powder produced in this way has a high coercive force H c of about 10 kA / cm and can be processed into powerful permanent magnets.
  • An SmCos base alloy is crushed down to particle sizes smaller than 500 ⁇ m and then with the help of a
  • the powder produced in this way has a high coercive force H c of about 30 kA / cm and can be used for the production of powerful permanent magnets.

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  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)
  • Hard Magnetic Materials (AREA)
  • Powder Metallurgy (AREA)

Abstract

The aim of the invention is to provide a technologically controllable, economical method for producing a hard magnetic powder consisting of a samarium-cobalt base alloy for highly coercive permanent magnets. The inventive method is based on an HDDR (hydrogenation-disproportionation-desorption-recombination) treatment. In a first stage of the process, an initial powder is subjected to hydrogenation under hydrogen with disproportionation of the alloy. In a subsequent second stage, the powder is subjected to hydrogen desorption under vacuum conditions with recombination of the alloy. According to the invention, an initial powder containing samarium and cobalt is treated in the first stage of the process either at a high temperature of between 500 DEG C and 900 DEG C and with a high hydrogen pressure of > 0.5 MPa or by intensive fine grinding at a low temperature of between 50 DEG C and 500 DEG C and with a hydrogen pressure of > 0.15 MPa. The invention therefore provides a method for producing magnetic alloy powders from samarium-cobalt base alloys. Said magnetic alloy powders can in turn be used for producing highly coercive permanent magnets by hot compacting or plastic binding.

Description

Verfahren zur Herstellung eines MagnetlegierungspulversProcess for producing a magnetic alloy powder
Technisches GebietTechnical field
Die Erfindung bezieht sich auf das Gebiet der metallurgischen Verfahrenstechnik und betrifft ein Verfahren zur Herstellung eines Magnetlegierungspulvers für hartmagnetische Anwendungen. Das Pulver besteht aus einer Samanum-Kobalt- Basis-Legierung . Mit dem Pulver können hochkoerzitive Permanentmagnete durch Heißkompaktierung oder Kunststoffbindung hergestellt werden. Mit dem Pulver können derartige Permanentmagnete jedoch auch auf pulvermetallurgischem Wege durch Sintern erzeugt werden.The invention relates to the field of metallurgical process engineering and relates to a method for producing a magnetic alloy powder for hard magnetic applications. The powder consists of a samanum-cobalt-based alloy. The powder can be used to produce highly coercive permanent magnets by hot compaction or plastic binding. With the powder, however, such permanent magnets can also be produced by powder sintering by sintering.
Stand der TechnikState of the art
Permanentmagnete auf Sm-Co-Basis werden bisher vorwiegend auf pulvermetallurgischem Wege durch Sintern hergestelltSm-Co-based permanent magnets have so far mainly been produced by powder metallurgy by sintering
(K. Strnat and R. M. W. Strnat, J. Magn. Magn. Mater. 100 (1991) 38) . Zur Herstellung des dafür benotigten Sm-Co- Pulvers ist es bereits bekannt, zunächst eine entsprechende Legierung zu erschmelzen, diese nach dem Erstarren zu zerkleinern und m einem Passivierungsgas unterhalb der Phasentransformationstemperatur der Legierung warmezubehandeln (US 5 122 203) . Eine derartige Herstellungsweise hat den Nachteil, daß eine energie- und zeitaufwendige mehrstufige Wärmebehandlung notwendig ist, um hohe Koerzitivfeldstarken einzustellen. Des weiteren hat eine derartige Herstellungsweise den Nachteil, daß für Magnete des Sιri2Cθi7-Typs Additive wie Cu und Zr notwendig sind, um eine(K. Strnat and RMW Strnat, J. Magn. Magn. Mater. 100 (1991) 38). To produce the Sm-Co powder required for this, it is already known to first melt an appropriate alloy, to comminute it after solidification and to heat-treat it in a passivation gas below the phase transformation temperature of the alloy (US Pat. No. 5,122,203). Such a production method has the disadvantage that an energy-consuming and time-consuming multi-stage heat treatment is necessary in order to set high coercive field strengths. Furthermore, such a method of production has the disadvantage that additives such as Cu and Zr are necessary for magnets of the Si 2 Co 7 type 7 in order to
BESTATIGUNGSKOPfE Mikrostruktur einzustellen, die eine hohe Koerzitivfeidstarke durch den Pinmng-Mechanismus ermöglicht. Diese Additive verringern jedoch die Sattigungsmagnetisierung .CONFIRMATION HEADS Set microstructure that enables a high coercive force through the pinmng mechanism. However, these additives reduce the saturation magnetization.
Auf dem Gebiet der Herstellung von Magnetpulvern auf der Basis von Legierungen mit Elementen aus der Gruppe der Seltenen Erden (SE) ist seit langem der HD-Prozess (Hydrid- Dekrepitation) bekannt (US 5 580 396, Spalte 8, Zeilen 30 bis 41; Rare-earth Iron Permanent Magnets, ed. J.M.D. Coey, Oxford 1996, Seiten 346 bis 349 und Seiten 370 bis 380) . Dieser Prozess wird eingesetzt zum Zerkleinern von groben, kompakten Legierungskorpern, dient also zur Pulvererzeugung. Dabei wird der Effekt genutzt, dass der m die Zwischenkornphase oder auf die Zwischengitterplatze der SE- Verbindung diffundierte Wasserstoff zu einer Ausdehnung der Zwischenkornphase beziehungsweise zu einer Gitterdehnung der SE-Verbmdung fuhrt. Die durch die Ausdehnung bzw. Gitterdehnung hervorgerufenen Spannungen fuhren zur mter- und mtergranularer Rissbildung und schließlich zu einem regelrechten Zerplatzen beziehungsweise Zerstauben (Dekrepitieren) des hydrierten Materials. Dieser Pulverisierungsvorgang kann auch noch durch die Einwirkung von Vibrationen (DE 28 16 538) oder durch den Einsatz einer Schwmgmuhle (CH 560 955) unterstutzt werden.The HD process (hydride decrepitation) has long been known in the field of the manufacture of magnetic powders based on alloys with elements from the rare earth element group (SE) (US Pat. No. 5,580,396, column 8, lines 30 to 41; Rare-earth Iron Permanent Magnets, ed.JMD Coey, Oxford 1996, pages 346 to 349 and pages 370 to 380). This process is used for crushing coarse, compact alloy bodies, and is therefore used for powder production. The effect is used here that the hydrogen diffused into the intermediate grain phase or onto the intermediate lattice sites of the SE compound leads to an expansion of the intermediate grain phase or to a lattice extension of the SE compound. The stresses caused by the expansion or lattice expansion lead to mter- and mtergranular crack formation and finally to a real bursting or dusting (decrepitating) of the hydrogenated material. This pulverization process can also be supported by the action of vibrations (DE 28 16 538) or by using a sponging mill (CH 560 955).
Beim Anwenden des HD-Prozesses für eine Verbindung AxBy, m der A ein Element der Seltenen Erden sei und B für ein oder mehrere andere Elemente (zumeist Ubergangsmetalle) steht, findet folgende Reaktion statt:When using the HD process for a compound A x B y , where A is a rare earth element and B stands for one or more other elements (mostly transition metals), the following reaction takes place:
A>By + z/2 H2 - AxByHz (HD-Prozess)A > B y + z / 2 H 2 - A x B y H z (HD process)
Nach dem eigentlichen HD-Prozess findet dann oftmals bei derAfter the actual HD process then often takes place at the
Weiterverarbeitung des erzeugten Pulvers zum Endprodukt im Zuge der sich anschließenden Prozessschritte, zum Beispiel beim Sintern, noch ein Entfernen/Desorbieren des Wasserstoffs statt, bei dem die Reaktion AxByHz -> AxBy + z/2 H2 ablauft.Further processing of the powder produced to the end product in the course of the subsequent process steps, for example during sintering, the hydrogen is still removed / desorbed, in which the reaction A x B y H z -> A x B y + z / 2 H 2 takes place.
Es ist auch bereits bekannt, bei der Herstellung von Magnetpulvern aus insbesondere Nd-Fe-B-Legierungen zur Verbesserung der magnetischen Eigenschaften das Verfahren der HDDR (Hydrierung-Disproportionierung-Desorption-It is also already known to use the process of HDDR (hydrogenation-disproportionation-desorption-) in the production of magnetic powders from in particular Nd-Fe-B alloys to improve the magnetic properties.
Rekombmation) anzuwenden (EP 0 304 054; EP 0 516 264; DE 196 07 747) . Bei dieser Behandlung wird das Pulver m einer 1. Verfahrensstufe m einer Wasserstoffatmosphare mit einem niedrigen Druck im Bereich von 0, 8 x 105 Pa bis höchstens 0,15 MPa hydriert. Infolge dieserRecombination) (EP 0 304 054; EP 0 516 264; DE 196 07 747). In this treatment, the powder is hydrogenated in a first process stage in a hydrogen atmosphere at a low pressure in the range from 0.8 × 10 5 Pa to at most 0.15 MPa. As a result of this
Wasserstoffbehandlung findet eine chemische ReaktionHydrogen treatment finds a chemical reaction
(Disproportiomerung) statt, das heißt, die ursprungliche Phase zerfallt unter Bildung eines binaren Hydrids und der übrigen Elemente oder Kombinationen der Elemente der Ausgangsphase .(Disproportionation) instead, that is, the original phase disintegrates to form a binary hydride and the remaining elements or combinations of the elements of the starting phase.
Diese chemische Reaktion kann schematisch (unter analoger Verwendung der obengenannten Modellsubstanz AxBy) wie folgt dargestellt werden:This chemical reaction can be represented schematically (using the model substance A x B y mentioned above) as follows:
AxBy + z/2 H2 -> AXHZ + yB (HDDR-Stufe 1)A x B y + z / 2 H 2 -> A X H Z + yB (HDDR level 1)
Anschließend werden dann m einer 2. Verfahrensstufe mittels einer Wärmebehandlung unter Vakuumbedingungen die hydrierten Legierungselemente wieder dehydriert, bei gleichzeitiger Rekombination der m Stufe 1 zersetzten Legierungszusammensetzung gemäß folgender Reaktionsgleichung:The hydrogenated alloy elements are then dehydrated again in a second process stage by means of a heat treatment under vacuum conditions, with simultaneous recombination of the alloy composition decomposed in stage 1 according to the following reaction equation:
AXHZ + yB - AxBy + z/2 H2 (HDDR-Stufe 2 ,A X H Z + yB - A x B y + z / 2 H 2 (HDDR level 2,
Durch die HDDR-Behandlung wird eine Kπstallitgroße erreicht , die im Bereich der Emdomanenteilchengroße liegt , die z . B . für Nd2Fe-idB und etwa 300 nm betragt . Diese Kornfemung, die zu einer Verbesserung der magnetischen Eigenschaften des Magnetpulvers fuhrt, ist das Hauptziel der HDDR-Behandlung und nicht - wie beim HD-Prozess - die Pulverherstellung. An dieser Stelle sei ausdrücklich darauf hingewiesen, dass der HD-Prozess nicht mit der ersten Stufe der HDDR-Behandlung identisch ist, wie die ersten beiden Buchstaben der Abkürzung "HDDR" eventuell suggerieren konnten .Through the HDDR treatment a Kπstallit size is achieved, which is in the range of the Emdoman particle size z. B. for Nd 2 Fe-idB and is about 300 nm. This Grain detachment, which leads to an improvement in the magnetic properties of the magnetic powder, is the main goal of the HDDR treatment and not - as in the HD process - the powder production. At this point, it should be expressly pointed out that the HD process is not identical to the first stage of HDDR treatment, as the first two letters of the abbreviation "HDDR" might suggest.
In der HDDR-Stufe 1 kommt es beim Aufheizen bis zu den für die oben dargestellte Reaktion notwendigen Temperaturen von 500°C bis 1000°C zwar oft zu der für den HD-Prozess typischen Wasserstoffabsorption wie sie oben m der Gleichung für den HD-Prozess beschrieben ist, jedoch stellt dies nur eine Zwischenreaktion dar, der unmittelbar die Desorption des Wasserstoffs folgt. Die HDDR-Behandlung kann völlig unabhängig vom HD-Prozess durchgeführt werden, wie zum Beispiel mit dem "solιd-HDDR"-Prozess gezeigt wurde, bei dem das Wasserstoffgas erst bei der für die Disproportionierung (HDDR-Stufe 1) notwendigen Temperatur m den Peaktor eingelassen wird und es so zu keiner mterstitiellen Absorption des Wasserstoffs und damit nicht zum HD-Prozess kommt (Gutfleisch et al . , J. Alloys Compd. 215 (1994) 227).In HDDR stage 1, heating up to the temperatures of 500 ° C to 1000 ° C necessary for the above-described reaction often results in the hydrogen absorption typical of the HD process, as described above in the equation for the HD process is described, however, this is only an intermediate reaction, which is immediately followed by the desorption of the hydrogen. The HDDR treatment can be carried out completely independently of the HD process, as has been shown, for example, with the “sol-HDDR” process, in which the hydrogen gas only reaches the peactor at the temperature m required for disproportionation (HDDR stage 1) is admitted and so there is no interstitial absorption of the hydrogen and thus no HD process (Gutfleisch et al., J. Alloys Compd. 215 (1994) 227).
Bekannt ist auch die zunehmende Stabilisierung von SE-Fe- Verbmdungen im Falle der Substitution des Fe durch Co (A. Fujita and I. R. Harris, IEEE Trans. Magn. 30 (1994) 860) .Also known is the increasing stabilization of SE-Fe compounds when Fe is substituted by Co (A. Fujita and I.R. Harris, IEEE Trans. Magn. 30 (1994) 860).
Eine Übertragung der für Nd-Fe-B-Magnetpulver bekannten HDDR- Verfahrensbedmgungen auf Sm-Co-Magnetpulver ist nicht möglich, da eine Disproportionierungsreaktion, wie sie in der oben dargestellten Stufe 1 der HDDR-Behandlung stattfindet, unter den üblichen HDDR-Bedmgungen (500 < T < 1000°C, -0,1 MPa Wasserstoffdruck) bei Sm-Co- Magnetpulvern wegen der großen Stabilität dieser Legierungen nicht eintritt.It is not possible to transfer the HDDR process conditions known for Nd-Fe-B magnetic powder to Sm-Co magnetic powder, since a disproportionation reaction, as takes place in stage 1 of the HDDR treatment shown above, takes place under the usual HDDR conditions ( 500 <T <1000 ° C, -0.1 MPa hydrogen pressure) at Sm-Co- Magnetic powders do not occur because of the great stability of these alloys.
Darstellung der ErfindungPresentation of the invention
Der Erfindung liegt die Aufgabe zugrunde, ein Verfahren zu schaffen, das eine technologisch beherrschbare und kostengünstige Herstellung eines hartmagnetischen, aus einer Samarium-Kobalt-Basis-Legierung bestehenden Pulvers für hochkoerzitive Permanentmagnete ermöglicht.The invention has for its object to provide a method which enables a technologically controllable and inexpensive production of a hard magnetic powder consisting of a samarium-cobalt-base alloy for highly coercive permanent magnets.
Diese Aufgabe wird nach der Erfindung mit dem m den Patentansprüchen beschriebenen Herstellungsverfahren gelost.This object is achieved according to the invention with the manufacturing method described in the claims.
Das Verfahren basiert auf einer HDDR-Behandlung , bei der ein Ausgangspulver in einer ersten Verfahrensstufe unter Wasserstoff einer Hydrierung mit Disproportiomerung der Legierung und m einer anschließenden zweiten Verfahrensstufe unter Vakuumbedingungen einer Wasserstoffdesorption mit Rekombination der Legierung unterworfen wird. Erfmdungsgemaß wird dabei ein Samarium und Kobalt enthaltendes Ausgangspulver in der ersten Verfahrensstufe entweder bei einer hohen Temperatur im Bereich von 500 °C bis 900 °C und mit einem hohen Wasserstoffdruck von > 0,5 MPa oder aber unter Anwendung einer intensiven Feinmahlung bei einer niedrigen Temperatur im Bereich von 50 °C bis 500 °C und mit einem Wasserstoffdruck von > 0,15 MPa behandelt.The process is based on an HDDR treatment in which a starting powder is subjected to hydrogenation with disproportionation of the alloy in a first process step under hydrogen and in a subsequent second process step to hydrogen desorption with recombination of the alloy under vacuum conditions. According to the invention, a starting powder containing samarium and cobalt is used in the first process stage either at a high temperature in the range from 500 ° C. to 900 ° C. and with a high hydrogen pressure of> 0.5 MPa or using intensive fine grinding at a low temperature in the range from 50 ° C to 500 ° C and treated with a hydrogen pressure of> 0.15 MPa.
Beide Verfahrensvarianten fuhren zur Disproportiomerung der Ausgangsphase und zur Bildung eines kristallinen binaren Samarium-Hydrids .Both process variants lead to disproportionation of the starting phase and to the formation of a crystalline binary samarium hydride.
Im Falle der Anwendung der hohen Temperatur im Bereich von 500 °C bis 900 °C wird vorzugsweise ein Wasserstoffdruck im Bereich von 1,0 MPa bis 5,0 MPa angewandt. Gemäß einer zweckmäßigen Ausgestaltung des Verfahrens wird die intensive Feinmahlung wahrend einer Dauer von 1 h bis 100 h durchgeführt.In the case of using the high temperature in the range of 500 ° C to 900 ° C, a hydrogen pressure in the range of 1.0 MPa to 5.0 MPa is preferably applied. According to an expedient embodiment of the method, the intensive fine grinding is carried out for a period of 1 h to 100 h.
Als Ausgangspulver kann im Falle der Anwendung einer intensiven Feinmahlung erfmdungsgemaß ein Pulver einer Sm- Co-Basis-Legierung oder aber eine Pulvermischung, bestehend aus den einzelnen Elementen einer S -Co-Basis-Legierung und/oder bestehend aus einer oder mehreren, zur Herstellung einer Sm-Co-Basis-Legierung geeigneten Vorlegierungen, eingesetzt werden.According to the invention, a starting powder can be a powder of an Sm-Co-based alloy or a powder mixture consisting of the individual elements of an S-Co-based alloy and / or consisting of one or more, for use in the case of intensive fine grinding a Sm-Co-based alloy suitable master alloys are used.
Das Ausgangspulver sollte im Falle der Anwendung einer intensiven Feinmahlung vorzugsweise bei einem Wasserstoffdruck im Bereich von 0,5 MPa bis 2,5 MPa feingemahlen werden.In the case of intensive fine grinding, the starting powder should preferably be finely ground at a hydrogen pressure in the range from 0.5 MPa to 2.5 MPa.
Zweckmaßigerweise wird die Wasserstoffdesorptionsbehandlung an dem erhaltenen Magnetpulver mittels einer Wärmebehandlung im Bereich von 500 °C bis 1000 °C durchgeführt.The hydrogen desorption treatment is expediently carried out on the magnetic powder obtained by means of a heat treatment in the range from 500 ° C. to 1000 ° C.
Nach der Erfindung werden bevorzugt solche Ausgangspulver eingesetzt, die zu Magnetlegierungspulvern mit der Legierungszusammensetzung SmxCoιoo-x mit 10 < x < 30 oder der Legierungszusammensetzung SmxCθιoo-x-a-b-cFeaCUbZrc mit 10 < x < 30, a < 45, b < 15 und c < 15 fuhren.According to the invention, preference is given to using starting powders which form magnetic alloy powders having the alloy composition Sm x Coιoo- x with 10 <x <30 or the alloy composition Sm x Cθιoo- x - a - b - c Fe a CU b Zr c with 10 <x <30, a <45, b <15 and c <15.
Mit dem erfmdungsgemaßen Verfahren wird eine neue Möglichkeit für die magnetische Härtung von Sm-Co-Basis- Verbmdungen geschaffen. Durch das Verfahren ergeben sich neue Ansätze für eine Optimierung der magnetischen Eigenschaften von Sm-Co-Magneten, die zu einer Verbesserung der Eigenschaften fuhrt und eine kostengünstige Alternative für die Herstellung solcher Magnete darstellt. Dies schließt die Möglichkeit einer Homogenisierung der Mikrostruktur der Sm-Co-Basisverbmdungen ein, wodurch eine langwierige Homogenisierung bei hohen Temperaturen entfallen kann.The method according to the invention creates a new possibility for the magnetic hardening of Sm-Co base compounds. The method opens up new approaches for optimizing the magnetic properties of Sm-Co magnets, which leads to an improvement in the properties and represents an inexpensive alternative for the production of such magnets. This closes the possibility of homogenizing the microstructure of the Sm-Co base compounds, which means that lengthy homogenization at high temperatures can be dispensed with.
Beste Wege zur Ausfuhrung der ErfindungBest ways to carry out the invention
Nachstehend ist die Erfindung an Hand von Ausfuhrungsbeispielen naher erläutert.The invention is explained in more detail below on the basis of exemplary embodiments.
Beispiel 1example 1
Eine erschmolzene Sm2 (Co, Fe, Cu, Zr) ι7-Ausgangslegιerung, wie sie üblicherweise für die Herstellung von S -Co Sintermagneten verwendet wird und deren Koerzitivfeidstarken durch den Pinmng-Mechamsmus bestimmt werden, wird bis auf Partikelgroßen < 160 μ zerkleinert und anschließend m einer Wasserstoffatmosphare von 2 MPa bis zu einer Temperatur von 600°C aufgeheizt und eine halbe Stunde bei dieser Temperatur gehalten. Durch den Wasserstoff wird das Pulver hydriert, wobei eine Disproportiomerung der Legierung stattfindet. Anschließend wird das Pulver unter standigem Abpumpen bis 750°C aufgeheizt und bei dieser Temperatur erneut eine halbe Stunde gehalten.A melted Sm 2 (Co, Fe, Cu, Zr) ι 7 starting alloy, as is usually used for the production of S-Co sintered magnets and whose coercive strengths are determined by the pinmng mechanism, is crushed down to particle sizes <160 μ and then heated in a hydrogen atmosphere of 2 MPa to a temperature of 600 ° C. and held at this temperature for half an hour. The powder is hydrogenated by the hydrogen, with a disproportionation of the alloy taking place. The powder is then heated to 750 ° C. with constant pumping and is held at this temperature again for half an hour.
Das so hergestellte Pulver weist eine hohe Koerzitivfeidstarke Hc von etwa 5 kA/cm auf und kann zu leistungsfähigen Permanentmagneten verarbeitet werden.The powder produced in this way has a high coercive force H c of about 5 kA / cm and can be processed into powerful permanent magnets.
Beispiel 2Example 2
Eine SmCos Ausgangslegierung wird bis auf Partikelgroßen < 500 μm zerkleinert und anschließend einer Wasserstoffatmosphare von 2 MPa bis zu einer Temperatur von 600°C aufgeheizt und eine halbe Stunde bei dieser Temperatur gehalten. Anschließend wird das Pulver unter standigem Abpumpen bis 750°C aufgeheizt und bei dieser Temperatur erneut eine halbe Stunde gehalten.An SmCos base alloy is crushed to particle sizes <500 μm and then heated in a hydrogen atmosphere of 2 MPa to a temperature of 600 ° C and held at this temperature for half an hour. Then the powder is under constant Pumping heated up to 750 ° C and held again at this temperature for half an hour.
Das auf diese Weise hergestellte Pulver weist eine hohe Koerzitivfeldstarke Hc von etwa 10 kA/cm auf und ist für die Herstellung leistungsfähiger Permanentmagnete verwendbar.The powder produced in this way has a high coercive force H c of about 10 kA / cm and can be used for the production of powerful permanent magnets.
Beispiel 3Example 3
Eine erschmolzene Sm2 (Co, Fe, Cu, Zr) 17 Ausgangslegierung, wie sie üblicherweise für die Herstellung von Sm-Co- Smtermagneten verwendet wird und deren Koerzitivfeidstarken durch den Pmnmg-Mechanismus bestimmt werden, wird bis auf Partikelgroßen kleiner 160 μm zerkleinert und anschließend mit Hilfe einer Vibrationsmuhle m einer Wasserstoffatmosphare von 1 MPa bei einer Temperatur des Mahlbechers von 350°C wahrend einer Dauer von 20 h intensiv gemahlen. Hierbei findet neben einer Feinmahlung gleichzeitig infolge des anwesenden Wasserstoffs eine Disproportiomerung der Legierung statt. Anschließend wird das Pulver zur Durchfuhrung einer Wasserstoffdesorption unter standigem Abpumpen von Wasserstoff bis auf 750°C aufgeheizt und bei dieser Temperatur eine halbe Stunde gehalten.A melted Sm 2 (Co, Fe, Cu, Zr) 17 starting alloy, as is usually used for the production of Sm-Co smter magnets and whose coercive forces are determined by the Pmnmg mechanism, is crushed down to particle sizes smaller than 160 μm and then, using a vibratory mill in a hydrogen atmosphere of 1 MPa, at a grinding bowl temperature of 350 ° C., intensively ground for a period of 20 hours. In addition to fine grinding, a disproportionation of the alloy takes place simultaneously due to the hydrogen present. The powder is then heated to 750 ° C. while hydrogen is being pumped out, and is held at this temperature for half an hour in order to carry out hydrogen desorption.
Das auf diese Weise hergestellte Pulver weist eine hohe Koerzitivfeldstarke Hc von etwa 10 kA/cm auf und kann zu leistungsfähigen Permanentmagneten verarbeitet werden.The powder produced in this way has a high coercive force H c of about 10 kA / cm and can be processed into powerful permanent magnets.
Beispiel 4Example 4
Eine SmCos Ausgangslegierung wird bis auf Partikelgroßen kleiner 500 μm zerkleinert und anschließend mit Hilfe einerAn SmCos base alloy is crushed down to particle sizes smaller than 500 μm and then with the help of a
Vibrationsmuhle m einer Wasserstoffatmosphare von 1 MPa bei einer Temperatur des Mahlbechers von 350 °C wahrend einer Dauer von 20 h intensiv gemahlen. Hierbei findet neben einer Feinmahlung gleichzeitig infolge des anwesenden Wasserstoffs eine Disproportiomerung der Legierung statt. Anschließend wird das Pulver zur Durchfuhrung einer Wasserstoffdesorption unter standigem Abpumpen von Wasserstoff bis auf 900°C aufgeheizt und bei dieser Temperatur eine halbe Stunde gehalten.Vibratory mill in a hydrogen atmosphere of 1 MPa at a temperature of the grinding bowl of 350 ° C for a period of 20 hours intensively ground. Here takes place next to one Fine grinding a disproportionation of the alloy takes place simultaneously due to the presence of hydrogen. The powder is then heated to 900 ° C. while hydrogen is being pumped out, and is kept at this temperature for half an hour in order to carry out a hydrogen desorption.
Das auf diese Weise hergestellte Pulver weist eine hohe Koerzitivfeldstarke Hc von etwa 30 kA/cm auf und ist für die Herstellung leistungsfähiger Permanentmagnete verwendbar. The powder produced in this way has a high coercive force H c of about 30 kA / cm and can be used for the production of powerful permanent magnets.

Claims

Patentansprüche claims
1. Verfahren zur Herstellung eines Magnetlegierungspulvers für hartmagnetische Anwendungen, indem ein Ausgangspulver einer HDDR-Behandlung unterworfen wird, bei der in einer ersten Verfahrensstufe in einer Wasserstoffatmosphare eine Hydrierung mit Disproportionierung der Legierung und in einer anschließenden zweiten Verfahrensstufe unter Vakuumbedingungen eine Wasserstoffdesorption mit Rekombination der Legierung ausgeführt wird, dadurch gekennzeichnet, dass ein Samarium und Kobalt enthaltendes Ausgangspulver in der ersten Verfahrensstufe entweder bei einer hohen Temperatur im Bereich von 500 °C bis 900 °C und mit einem hohen Wasserstoffdruck von > 0,5 MPa oder aber unter Anwendung einer intensiven Feinmahlung bei einer niedrigen Temperatur im Bereich von 50 °C bis 500 °C und mit einem Wasserstoffdruck von > 0,15 MPa behandelt wird.1. A process for producing a magnetic alloy powder for hard magnetic applications by subjecting a starting powder to an HDDR treatment in which, in a first process step, hydrogenation with disproportionation of the alloy in a hydrogen atmosphere and in a subsequent second process step under vacuum conditions, hydrogen desorption with recombination of the alloy is carried out, characterized in that a starting powder containing samarium and cobalt in the first process stage either at a high temperature in the range from 500 ° C to 900 ° C and with a high hydrogen pressure of> 0.5 MPa or using intensive fine grinding is treated at a low temperature in the range of 50 ° C to 500 ° C and with a hydrogen pressure of> 0.15 MPa.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass im Falle der Anwendung der hohen Temperatur im Bereich von 500 °C bis 900 °C ein Wasserstoffdruck im Bereich von 1,0 MPa bis 5,0 MPa angewandt wird.2. The method according to claim 1, characterized in that in the case of application of the high temperature in the range from 500 ° C to 900 ° C, a hydrogen pressure in the range from 1.0 MPa to 5.0 MPa is applied.
3. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die intensive Feinmahlung während einer Dauer von 1 h bis 100 h durchgeführt wird. 3. The method according to claim 1, characterized in that the intensive fine grinding is carried out for a period of 1 h to 100 h.
4. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass im Falle der Anwendung einer intensiven Feinmahlung als Ausgangspulver ein Pulver einer Sm-Co-Basis-Legierung oder eine Pulvermischung, bestehend aus den einzelnen Elementen einer Sm-Co-Basis-Legierung und/oder bestehend aus einer oder mehreren, zur Herstellung einer Sm-Co- Basis-Legierung geeigneten Vorlegierungen, eingesetzt wird.4. The method according to claim 1, characterized in that in the case of using an intensive fine grinding as the starting powder, a powder of an Sm-Co-based alloy or a powder mixture consisting of the individual elements of an Sm-Co-based alloy and / or consisting of one or more master alloys suitable for the production of an Sm-Co base alloy.
5. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass im Falle der Anwendung einer intensiven Feinmahlung das Ausgangspulver bei einem Wasserstoffdruck im Bereich von 0,5 MPa bis 2,5 MPa feingemahlen wird.5. The method according to claim 1, characterized in that in the case of using an intensive fine grinding, the starting powder is finely ground at a hydrogen pressure in the range from 0.5 MPa to 2.5 MPa.
6. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die Wasserstoffdesorptionsbehandlung mittels einer Wärmebehandlung im Bereich von 500 °C bis 1000 °C durchgeführt wird.6. The method according to claim 1, characterized in that the hydrogen desorption treatment is carried out by means of a heat treatment in the range from 500 ° C to 1000 ° C.
7. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass ein Magnetlegierungspulver der7. The method according to claim 1, characterized in that a magnetic alloy powder
Legierungszusammensetzung SmxCθιoo-x mit 10 < x < 30 hergestellt wird.Alloy composition Sm x Cθιoo- x with 10 <x <30 is produced.
8. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass ein Magnetlegierungspulver m der8. The method according to claim 1, characterized in that a magnetic alloy powder m the
Legierungszusammensetzung SmxCθιoo-x-a-b-cFeaCubZrc mit 10 < x < 30, a < 45, b < 15 und c < 15 hergestellt wird. Alloy composition Sm x Cθιoo- x - a - b - c Fe a Cu b Zr c with 10 <x <30, a <45, b <15 and c <15 is produced.
EP98956933A 1997-11-20 1998-11-19 Method for producing a magnetic alloy powder Expired - Lifetime EP1032940B1 (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
DE1997151366 DE19751366C2 (en) 1997-11-20 1997-11-20 Process for the production of a hard magnetic samarium-cobalt base material
DE19751367 1997-11-20
DE19751367A DE19751367C2 (en) 1997-11-20 1997-11-20 Process for producing a hard magnetic powder consisting of a samarium-cobalt-based alloy
DE19751366 1997-11-20
PCT/EP1998/007418 WO1999027544A1 (en) 1997-11-20 1998-11-19 Method for producing a magnetic alloy powder

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