EP4227963A1 - Method for producing a magnetic material and magnetic material - Google Patents
Method for producing a magnetic material and magnetic material Download PDFInfo
- Publication number
- EP4227963A1 EP4227963A1 EP22155955.2A EP22155955A EP4227963A1 EP 4227963 A1 EP4227963 A1 EP 4227963A1 EP 22155955 A EP22155955 A EP 22155955A EP 4227963 A1 EP4227963 A1 EP 4227963A1
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- EP
- European Patent Office
- Prior art keywords
- lanthanide
- salt
- magnetic material
- grains
- mixture
- Prior art date
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- 239000000696 magnetic material Substances 0.000 title claims abstract description 39
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 12
- 150000002602 lanthanoids Chemical class 0.000 claims abstract description 65
- 229910052747 lanthanoid Inorganic materials 0.000 claims abstract description 55
- 150000003839 salts Chemical class 0.000 claims abstract description 34
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 29
- 239000000203 mixture Substances 0.000 claims abstract description 20
- 239000006247 magnetic powder Substances 0.000 claims abstract description 15
- 229910052742 iron Inorganic materials 0.000 claims abstract description 14
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims abstract description 13
- 239000011230 binding agent Substances 0.000 claims abstract description 12
- 229910052796 boron Inorganic materials 0.000 claims abstract description 12
- 239000002904 solvent Substances 0.000 claims abstract description 12
- 238000009792 diffusion process Methods 0.000 claims abstract description 10
- 238000001764 infiltration Methods 0.000 claims abstract description 10
- 230000008595 infiltration Effects 0.000 claims abstract description 10
- 238000010438 heat treatment Methods 0.000 claims abstract description 8
- 238000007493 shaping process Methods 0.000 claims abstract description 5
- 238000000034 method Methods 0.000 claims description 28
- 229910052692 Dysprosium Inorganic materials 0.000 claims description 14
- KBQHZAAAGSGFKK-UHFFFAOYSA-N dysprosium atom Chemical compound [Dy] KBQHZAAAGSGFKK-UHFFFAOYSA-N 0.000 claims description 14
- 239000012071 phase Substances 0.000 claims description 14
- 229910052779 Neodymium Inorganic materials 0.000 claims description 13
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 claims description 13
- GZCRRIHWUXGPOV-UHFFFAOYSA-N terbium atom Chemical compound [Tb] GZCRRIHWUXGPOV-UHFFFAOYSA-N 0.000 claims description 12
- 229910052771 Terbium Inorganic materials 0.000 claims description 11
- 239000000463 material Substances 0.000 claims description 11
- 239000007791 liquid phase Substances 0.000 claims description 10
- 238000009826 distribution Methods 0.000 claims description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 claims description 4
- 230000015572 biosynthetic process Effects 0.000 claims description 4
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 3
- 229910052791 calcium Inorganic materials 0.000 claims description 3
- 239000011575 calcium Substances 0.000 claims description 3
- 239000002245 particle Substances 0.000 claims description 2
- XRADHEAKQRNYQQ-UHFFFAOYSA-K trifluoroneodymium Chemical compound F[Nd](F)F XRADHEAKQRNYQQ-UHFFFAOYSA-K 0.000 claims description 2
- 239000011148 porous material Substances 0.000 abstract description 5
- 238000005245 sintering Methods 0.000 description 10
- ZDVYABSQRRRIOJ-UHFFFAOYSA-N boron;iron Chemical compound [Fe]#B ZDVYABSQRRRIOJ-UHFFFAOYSA-N 0.000 description 8
- 239000000243 solution Substances 0.000 description 8
- 239000007788 liquid Substances 0.000 description 3
- 238000001000 micrograph Methods 0.000 description 3
- 239000000956 alloy Substances 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 229910001634 calcium fluoride Inorganic materials 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 210000003739 neck Anatomy 0.000 description 2
- 229910000521 B alloy Inorganic materials 0.000 description 1
- 240000000581 Triticum monococcum Species 0.000 description 1
- QJVKUMXDEUEQLH-UHFFFAOYSA-N [B].[Fe].[Nd] Chemical compound [B].[Fe].[Nd] QJVKUMXDEUEQLH-UHFFFAOYSA-N 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 150000002222 fluorine compounds Chemical class 0.000 description 1
- 238000010191 image analysis Methods 0.000 description 1
- 238000000462 isostatic pressing Methods 0.000 description 1
- 239000002648 laminated material Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920005596 polymer binder Polymers 0.000 description 1
- 239000002491 polymer binding agent Substances 0.000 description 1
- 238000002459 porosimetry Methods 0.000 description 1
- -1 salts calcium fluoride Chemical class 0.000 description 1
- 238000005029 sieve analysis Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000003826 uniaxial pressing Methods 0.000 description 1
Images
Classifications
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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
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- 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
- H01F41/0293—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 diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets
Definitions
- the present invention relates to a method for producing a magnetic material according to patent claim 1 and a magnetic material according to patent claim 10.
- Metallic high-performance magnets also have high magnetic losses when used with high frequencies.
- such a material for example based on iron, boron and neodymium, is segmented by sawing and reassembled using a polymer binder to form a laminate.
- a polymer binder to form a laminate.
- laminate materials have good permanent magnetic properties, they are, as already mentioned, no longer suitable for use in high-load electrical machines due to the polymer bond (here in the laminate and not in the microstructure) at temperatures below 100 °C .
- the object of the invention is to provide a method for producing a magnetic material and a magnetic material which, compared to the prior art, have a higher temperature resistance and also have better permanent magnetic properties.
- the solution to the problem consists in a method for producing a magnetic material with the features of patent claim 1 and in a sintered, polymer-free magnetic material with the features of patent claim 10.
- infiltration means the introduction of a fluid into an open-pored system.
- the fluid including the solvent, can be gaseous, with the substance to be introduced condensing on the pore walls and being deposited there.
- the infiltration of liquid media which is driven on the basis of capillary effects and capillary forces, preferably takes place.
- the solvent is also liquid here.
- the method described leads to a magnetic material that has exceptionally high permanent magnetic properties and at the same time shows a high temperature resistance of significantly more than 100 °C.
- the use of a second lanthanide in the border areas between the existing grains, which already have an iron-boron alloy and a lanthanide contained therein, causes a significant increase in the permanent magnetic properties compared to pure iron-boron-lanthanide materials.
- the salt which is also infiltrated with the second lanthanide into the pores of the porous preliminary body causes a reduction in the electrical conductivity compared to a purely metallic permanent magnet based on iron, boron and lanthanide, for example also iron, boron and neodymium.
- the second lanthanide increases the magnetic properties and that the salt introduced with the second lanthanide reduces the electrical conductance in order to create high frequency stability.
- the first lanthanide is neodymium.
- Iron-boron-neodymium permanent magnets basically have very good permanent magnetic properties.
- the second lanthanide, which is infiltrated in the porous preliminary body together with salt, preferably has a higher atomic number than the first lanthanide.
- the elements dysprosium and terbium are suitable for this purpose, in particular in contrast to the first lanthanide neodymium. Mixtures or alloys of these elements can also be useful.
- a salt that is soluble in the liquid phase of the second lanthanide and combines with it is advantageously used as the added salt that reduces the electrical conductance of the magnetic material. Therefore e.g. B. the oxide of dysprosium or terbium very well suited.
- a fluoride can also be suitable as a salt, since fluorides can be easily dissolved in the liquid phase of the second lanthanide.
- the salts calcium fluoride or neodymium fluoride are particularly suitable.
- a further advantage of the invention is that, due to the process steps described, it is possible to use a grain size distribution which is between 100 and 300 micrometers. This preferably includes 80% of the grains of the magnetic powder present in the microstructure of the resulting material.
- the particle size distribution is determined by sieve analysis.
- the grain distribution in the microstructure of the magnetic material is analyzed by image analysis of a light micrograph of a micrograph of the magnetic material.
- the element distribution within the grains is determined by a quantified EDX evaluation based on a scanning electron microscope evaluation of the micrograph.
- Another component of the invention is a sintered, polymer-free magnetic material with the features of claim 10.
- This has a microstructure that is between 60 vol% and 80 vol% lanthanide iron boron grains.
- the grains have at least 80 at% iron and boron in their core. In their edge area, the grains contain more than 50 at% of a first lanthanide, which is present there in an increased concentration, in addition to the iron and boron.
- the magnetic material is characterized by the fact that between the lanthanide-FeB grains there is an intermediate phase that contains more than 50 at% of a second element from the lanthanide series, i.e. a second lanthanide that has a higher atomic number than the first lanthanide , which is present in the grains. Furthermore, this intermediate phase contains a salt, with the electrical conductivity of the magnetic material being less than 10 S/m.
- the magnetic material described has the same advantageous properties that have already been described with regard to the method for producing this magnetic material.
- the introduction of the second lanthanide into the intermediate phase, together with the salt described, leads on the one hand to an increase in the permanent magnetic properties with a simultaneous reduction in the electrical conductance by the salt.
- the permanent magnet itself, it is expedient to use neodymium as the first lanthanide element, which together with iron and boron results in a very good permanent magnet. Furthermore, it is expedient to use dysprosium or terbium or alloys thereof as the second lanthanide, which increases the magnetic properties even further.
- the oxide of dysprosium and terbium, or a fluoride of calcium or dysprosium, are also particularly suitable for dissolving in the second lanthanide and bringing about a reduction in the electrical conductance there.
- the magnet material is particularly preferably characterized by a low porosity, with this in particular being less than 20 vol%.
- the porosity is measured by mercury porosimetry.
- FIG 1 is purely schematic the manufacturing process for producing a magnetic material 2, which at the end of the process chain figure 1 is shown.
- a mixture 4 is first provided in any mixing device 48 , which comprises a magnetic powder 6 and a binder 10 .
- This mixture is shaped into a porous preform 12 in a shaping process using any desired shaping device 42, shown here for example in the form of a uniaxial press.
- any desired shaping device 42 shown here for example in the form of a uniaxial press.
- isostatic pressing of the preliminary body 12 or an extrusion method could also be used.
- the resulting preliminary body 12 thus has the binder 10 and the magnetic powder 6, wherein in a further step, a debinding step 14, in a debinding oven 44 at elevated temperature, for example at 220 ° C, the binder 10 is thermally decomposed and from the Pre-body 12 exits.
- This process step is called debinding.
- the formerly essentially dense preliminary body 12 has become a porous preliminary body 16 since the binder 10 previously contained has decomposed thermally or chemically and has escaped from the preliminary body 12 .
- the porous preform 16 is now fed to an infiltration step.
- a second mixture 18 is first provided, which includes a second lanthanide 20 and a salt 22, which are added together to a solvent 24, from which a solution 26 is formed.
- the solution 26 is infiltrated into the porous preform 16 by capillary forces.
- infiltration is to be understood broadly.
- the description using a solvent is an exemplary, advantageous embodiment.
- the lanthanide could also be brought to an appropriate melting temperature
- the salt 22 could be dissolved in it and the open-pored preform 16 could be infiltrated with the second mixture in the liquid phase in a high-temperature process.
- CVD or CVI chemical vapor deposition
- an infiltrated preliminary body 30 is spoken of, which is sintered in a further process step, a heat treatment 28 in a heat treatment furnace 46 at a sintering temperature to form the magnetic material 2 .
- the heat treatment 28 is preferably a diffusion-controlled sintering process in which there is preferably no liquid phase in the microstructure of a sintered body 52 (transitional state between infiltrated preliminary body 30 and magnetic material 2) during the process.
- a diffusion-controlled sintering process in which there is preferably no liquid phase in the microstructure of a sintered body 52 (transitional state between infiltrated preliminary body 30 and magnetic material 2) during the process.
- the sintered body 52 states of aggregation, which indeed have liquid phase fractions, but with the exchange of Materials between grains 32 diffusion processes dominate.
- a microstructure 34 as shown in figure 3 is shown can be achieved.
- FIG 3 a typical magnetic grain 32 of the magnetic powder 6 is first shown, which has an iron-boron (FeB) phase 36 in an inner region.
- FeB iron-boron
- an edge region 38 of the grain 32 there is a phase which is very strongly enriched with a first lanthanide, in particular neodymium.
- the atomic proportion of the neodymium in the edge region 38 preferably has more than 50%.
- 38 iron-boron atoms can also be present in the edge area. It has been found that a magnetic powder 6 designed in this way with the magnetic grains 32 and the edge region 38 rich in lanthanide described can produce a magnetic material 2 which has very good permanent magnetic properties.
- Such grains usually have a grain diameter of between 100 ⁇ m and 300 ⁇ m (preferably 200 ⁇ m), whereby they preferably have a grain substructure (not shown graphically here) in the size range of 5 ⁇ m and 15 ⁇ m, which belongs to the good permanent-magnetic or Contribute to hard magnetic properties.
- microstructure 34 is a result of the manufacturing process described, in particular through the infiltration of a porous preform 16 with a second lanthanide and a salt 22 and the subsequent diffusion-controlled sintering process 28.
- the microstructure 34 shown is characterized in particular by the figure 2 described grains 32, which have an iron-boron core and are surrounded by a border area 38 rich in neodymium. Occasionally, the grains 32 are also connected to one another by the formation of sinter necks 50 . For the most part, however, there is an intermediate phase 40 between the grains 32 , which comprises the second lanthanide 20 and the salt 22 .
- the second lanthanide 20 for example dysprosium or terbium, with a salt 22 of dysprosium or terbium or a calcium fluoride, dominates the intermediate phase 40.
- dysprosium or terbium atoms also diffuse in the edge region 38 of the grains 32.
- the iron-boron core of the grains 32 is replaced by neodymium and enriched with a heavier, higher atomic number lanthanide such as dysprosium or terbium, further enhancing the permanent magnetic properties of the iron-boron.
- the porosity of the microstructure 34 or of the magnetic material 2 is very low; it is preferably below 20% by volume, particularly preferably below 10% by volume. Such a low porosity can be achieved in particular by the sintering process described.
- the described microstructure 34 proves to be a typical microstructure that is achieved by a diffusion-controlled process. If the liquid phase were to dominate during production or during the sintering process, as is often the case in the prior art, then the microstructure would be dominated by melt phases.
- the original grain 32 is only present in a slightly modified form with a higher degree of lanthanide enrichment in the edge region 38 .
- grains 32 used to have a larger diameter than is usual in the prior art are expedient in the case of the described material 2 and the microstructure 34 for the grains 32 used to have a larger diameter than is usual in the prior art.
- Grains 32 have a diameter between 100 and 300 microns, preferably between 150 and 250 microns. You are in accordance figure 2 advantageous shape with core area 36 and edge area 38 can be produced better.
- a A grain 32 designed in this way leads to better permanent magnetic properties in the microstructure 34 or in the magnetic material 2 .
- liquid phase sintering processes require the use of grains smaller than 20 microns. Such small grains, which are not shown here, lead to poorer magnetic properties.
- Good hard magnetic magnet materials 2 which were produced by the method described or according to a microstructure figure 3 have a remanence B r of 1.1 T and a coercivity H c of about 2600 kA/m and an energy product (B ⁇ H) max of 225 kJ/m 3 in example A and a remanence B r in example B of 1.5 T and a coercivity Hc of about 1400 kA/m and an energy product (B ⁇ H) max of 410 kJ/m 3
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- Power Engineering (AREA)
- Chemical & Material Sciences (AREA)
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- Hard Magnetic Materials (AREA)
- Powder Metallurgy (AREA)
Abstract
Die Erfindung betrifft ein Verfahren zu Herstellung eines Magnetwerkstoffs (2), umfassend folgende Schritte:- Bereitstellen einer Mischung (4) eines Magnetpulvers (6) umfassend Eisen, Bor und ein erstes Lanthanoid (8), und ein Bindemittel (10),- Formgebung der Mischung (4) zu einem Vorkörper (12),- Durchführen eines Entbinderungsschrittes (14) zur Entfernung des Bindemittels (10) unter Ausbildung eines offenporigen Vorkörpers (16)- Bereitstellen einer zweiten Mischung (18) aus einem zweiten Lanthanoiden (20) und einem Salz (22) das einen elektrischen Leitwert von weniger als 10<sup>-1</sup> S/m aufweist,- Lösen dieser zweiten Mischung (18) in einem Lösungsmittel (24) zu einer Lösung (26) und- Infiltration des offenporigen Vorkörpers (16) mit der Lösung (26),- Entfernung des Lösungsmittels (24) und- Wärmebehandlung (28) des infiltrierten Vorkörpers (30) auf einem Temperaturniveau, dass zu einer Diffusion des zweiten Lanthanoiden (20) und des Salzes (22) in einem Grenzbereich zwischen Körner (32) des Magnetpulvers (6) führt.The invention relates to a method for producing a magnetic material (2), comprising the following steps: - providing a mixture (4) of a magnetic powder (6) comprising iron, boron and a first lanthanide (8) and a binder (10), - shaping the mixture (4) to form a preform (12),- carrying out a debinding step (14) to remove the binder (10) while forming an open-pored preform (16)- providing a second mixture (18) of a second lanthanide (20) and a salt (22) which has an electrical conductivity of less than 10<sup>-1</sup> S/m,- dissolving this second mixture (18) in a solvent (24) to form a solution (26), and- infiltration the open-pore preform (16) with the solution (26), - removal of the solvent (24) and - heat treatment (28) of the infiltrated preform (30) at a temperature level that leads to diffusion of the second lanthanide (20) and the salt ( 22) in a boundary area between grains (32) of the magnetic powder (6).
Description
Die vorliegende Erfindung betrifft ein Verfahren zur Herstellung eines Magnetwerkstoffes nach Patentanspruch 1 sowie einen Magnetwerkstoff nach Patentanspruch 10.The present invention relates to a method for producing a magnetic material according to patent claim 1 and a magnetic material according to
Metallische Hochleistungsmagnete weisen bei Anwendung mit hohen Frequenzen auch hohe magnetische Verluste auf. Hierzu existieren im Stand der Technik verschiedene Lösungsansätze. Es ist bekannt, dass ein geringerer elektrischer Leitwert des Magnetwerkstoffes die genannten Wirbelstromverluste reduzieren kann. Daher werden vielfach kunststoffgebundene Magnete, die einen metallisch-magnetisch wirkenden Anteil haben, hergestellt. Diese Magnete weisen gute dauermagnetische Eigenschaften auf, zeigen sich jedoch bei höheren Betriebstemperaturen aufgrund ihrer Kunststoffbindung als ungeeignet. Insbesondere Temperaturen über 100 °C führen bereits dazu, dass derartige Magnetwerkstoffe nur noch bedingt einsetzbar sind und ihre magnetischen Eigenschaften nicht entsprechend ausspielen können.Metallic high-performance magnets also have high magnetic losses when used with high frequencies. There are various approaches to solving this in the prior art. It is known that a lower electrical conductance of the magnetic material can reduce the eddy current losses mentioned. For this reason, plastic-bonded magnets that have a metallic-magnetic component are often produced. These magnets have good permanent magnetic properties, but are unsuitable for higher operating temperatures due to their plastic bonding. In particular, temperatures above 100 °C mean that such magnetic materials can only be used to a limited extent and their magnetic properties cannot be exploited accordingly.
Bei rein metallischen bzw. metallreichen Dauermagneten, beispielsweise auf der Basis von Neodym, Eisen und Bor, werden auch Materialien im sogenannten Flüssigphasensintern hergestellt. Hierbei wird eine neodymreiche Schicht um Eisenbohrkörner herum erzeugt, die bei einem Flüssigsinterprozess ausgebildet wird. Hierfür wird eine sehr feine Mikrostruktur der Eisenbohrkörner benötigt, die in der Regel weniger als 20 mµ beträgt. Der Flüssigphasensinterprozess ist aufwendig und schwer zu regulieren. Die so erzielten Ergebnisse führen jedoch nicht zu den gewünschten guten dauermagnetischen Eigenschaften. Insbesondere ist bei derartig hergestellten Magnetwerkstoffen der elektrische Leitwert zu hoch, sodass wieder die beschriebenen Wirbelstromverluste auftreten.In the case of purely metallic or metal-rich permanent magnets, for example based on neodymium, iron and boron, materials are also produced in what is known as liquid phase sintering. Here, a layer rich in neodymium is created around iron drill grains, which is formed during a liquid sintering process. This requires a very fine microstructure of the iron drill bits, which is usually less than 20 mµ. The liquid phase sintering process is complex and difficult to regulate. However, the results achieved in this way do not lead to the desired good permanent-magnetic properties. In particular, with magnetic materials produced in this way, the electrical conductance is too high, so that the described eddy current losses occur again.
Um dies zu verhindern, wird im Stand der Technik ein derartiger Werkstoff beispielsweise auf Basis von Eisen, Bor und Neodym durch Zersägen segmentiert und unter Verwendung eines Polymerbinders wieder zu einem Laminat zusammengesetzt. Derartige Laminat-Werkstoffe weisen zwar gute dauermagnetische Eigenschaften auf, sie sind jedoch, wie bereits erwähnt, aufgrund der Polymerbindung (hier im Laminat und nicht in der Mikrostruktur) bereits bei Temperaturen unter 100 °C nicht mehr gut für den Einsatz in hochbelasteten elektrischen Maschinen geeignet.In order to prevent this, in the prior art such a material, for example based on iron, boron and neodymium, is segmented by sawing and reassembled using a polymer binder to form a laminate. Although such laminate materials have good permanent magnetic properties, they are, as already mentioned, no longer suitable for use in high-load electrical machines due to the polymer bond (here in the laminate and not in the microstructure) at temperatures below 100 °C .
Die Aufgabe der Erfindung besteht darin, ein Verfahren zur Herstellung eines Magnetwerkstoffes sowie einen Magnetwerkstoff bereitzustellen, die gegenüber dem Stand der Technik eine höhere Temperaturbeständigkeit aufweisen und dabei auch bessere dauermagnetische Eigenschaften mit sich bringen.The object of the invention is to provide a method for producing a magnetic material and a magnetic material which, compared to the prior art, have a higher temperature resistance and also have better permanent magnetic properties.
Die Lösung der Aufgabe besteht in einem Verfahren zur Herstellung eines Magnetwerkstoffes mit den Merkmalen des Patentanspruches 1 sowie in einem gesinterten, polymerfreien Magnetwerkstoff mit den Merkmalen des Patentanspruches 10.The solution to the problem consists in a method for producing a magnetic material with the features of patent claim 1 and in a sintered, polymer-free magnetic material with the features of
Das entsprechende Verfahren gemäß Patentanspruch 1 zur Herstellung eines Magnetwerkstoffes umfasst folgende Schritte:
- Bereitstellen einer Mischung eines Magnetpulvers, die Eisen und Bor sowie ein erstes Lanthanoid und ein Bindemittel umfasst.
- Durchführen eines Entbinderungsschrittes zur Entfernung des Bindemittels unter Ausbildung eines offenporigen Formkörpers.
- Bereitstellen einer zweiten Mischung aus einem zweiten Lanthanoid und einem Salz, das einen elektrischen Leitwert von weniger als 10-1 S/m aufweist.
- Lösen dieser zweiten Mischung in einem Lösungsmittel zu einer Lösung und
- providing a magnetic powder mixture comprising iron and boron and a first lanthanide and a binder.
- Carrying out a debinding step to remove the binder with the formation of an open-pore molded body.
- providing a second mixture of a second lanthanide and a salt having a conductivity of less than 10-1 S/m.
- Dissolve this second mixture in a solvent to form a solution and
Infiltration des offenporigen Vorkörpers mit der Lösung.
- Entfernung des Lösungsmittels und
Wärmbehandlung des infiltrierten Vorkörpers auf einem Temperaturniveau, das zu einer Diffusion des zweiten Lanthanoiden und des Salzes in einem Grenzbereich zwischen Körnern des Magnetpulvers führt.
- removal of the solvent and
Heat treatment of the infiltrated preform at a temperature level that leads to diffusion of the second lanthanide and the salt in a boundary area between grains of the magnetic powder.
Unter Infiltration wird hierbei das Einbringen eines Fluids in ein offenporiges System verstanden. Das Fluid einschließlich des Lösungsmittels kann dabei gasförmig sein, wobei es zu einer Kondensation des einzubringenden Stoffes an den Porenwänden kommt und diese dort abscheiden. Bevorzugt erfolgt jedoch die Infiltration von flüssigen Medien, die auf Basis von Kapillareffekten und Kapillarkräften getrieben ist. Hierbei ist auch das Lösungsmittel flüssig.In this context, infiltration means the introduction of a fluid into an open-pored system. The fluid, including the solvent, can be gaseous, with the substance to be introduced condensing on the pore walls and being deposited there. However, the infiltration of liquid media, which is driven on the basis of capillary effects and capillary forces, preferably takes place. The solvent is also liquid here.
Gegenüber dem Stand der Technik führt das beschriebene Verfahren zu einem Magnetwerkstoff, der ausgesprochen hohe dauermagnetische Eigenschaften aufweist und dabei eine hohe Temperaturbeständigkeit von deutlich mehr als 100 °C zeigt. Die Verwendung eines zweiten Lanthanoiden, das in den Grenzbereichen zwischen den bereits bestehenden Körnern, die bereits eine Eisen-Bor-Legierung sowie ein darin enthaltenes Lanthanoid aufweisen, bewirkt noch einmal eine deutliche Erhöhung der dauermagnetischen Eigenschaften gegenüber reinen Eisen-Bor-Lanthanoid-Werkstoffen. Ferner bewirkt das ebenfalls mit dem zweiten Lanthanoid in die Poren des porösen Vorkörpers infiltrierte Salz eine Verringerung des elektrischen Leitwertes gegenüber einem rein metallischen Dauermagneten auf Basis von Eisen, Bor und Lanthanoid, beispielsweise auch Eisen, Bor und Neodym. Dadurch werden ohmsche Wirbelstromverluste bei hohen Frequenzen im Magnetwerkstoff reduziert, weshalb der Werkstoff bei höheren Frequenzen auch bessere magnetische Eigenschaften aufweist. Zusammenfassend kann gesagt werden, dass einerseits das zweite Lanthanoid die magnetischen Eigenschaften erhöht und dass mit dem zweiten Lanthanoid eingebrachtes Salz den elektrischen Leitwert verringert, um dabei eine hohe Frequenzbeständigkeit zu schaffen.Compared to the state of the art, the method described leads to a magnetic material that has exceptionally high permanent magnetic properties and at the same time shows a high temperature resistance of significantly more than 100 °C. The use of a second lanthanide in the border areas between the existing grains, which already have an iron-boron alloy and a lanthanide contained therein, causes a significant increase in the permanent magnetic properties compared to pure iron-boron-lanthanide materials. Furthermore, the salt which is also infiltrated with the second lanthanide into the pores of the porous preliminary body causes a reduction in the electrical conductivity compared to a purely metallic permanent magnet based on iron, boron and lanthanide, for example also iron, boron and neodymium. This reduces ohmic eddy current losses at high frequencies in the magnetic material, which is why the material also has better magnetic properties at higher frequencies. In summary, it can be said that on the one hand the second lanthanide increases the magnetic properties and that the salt introduced with the second lanthanide reduces the electrical conductance in order to create high frequency stability.
Dabei ist das erste Lanthanoid in einer bevorzugten Ausgestaltungsform der Erfindung Neodym. Eisen-Bor-Neodym Dauermagnete haben grundsätzlich sehr gute dauermagnetische Eigenschaften. Das zweite Lanthanoid, das in dem porösen Vorkörper zusammen mit Salz infiltriert wird, hat dabei bevorzugt eine höhere Ordnungszahl als das erste Lanthanoid. Hierfür bieten sich, insbesondere im Gegensatz zu dem ersten Lanthanoid Neodym die Elemente Dysprosium und Terbium an. Dabei können auch Mischungen bzw. Legierungen dieser Elemente zweckmäßig sein.In this case, in a preferred embodiment of the invention, the first lanthanide is neodymium. Iron-boron-neodymium permanent magnets basically have very good permanent magnetic properties. The second lanthanide, which is infiltrated in the porous preliminary body together with salt, preferably has a higher atomic number than the first lanthanide. The elements dysprosium and terbium are suitable for this purpose, in particular in contrast to the first lanthanide neodymium. Mixtures or alloys of these elements can also be useful.
Als beigefügtes Salz, das den elektrischen Leitwert des Magnetwerkstoffes reduziert, wird in vorteilhafter Weise ein Salz verwendet, das in der flüssigen Phase des zweiten Lanthanoids löslich ist und sich mit diesem verbindet. Daher ist z. B. das Oxid des Dysprosiums oder des Terbiums sehr gut geeignet. Grundsätzlich kann auch ein Fluorid als Salz geeignet sein, da sich Fluoride gut in der flüssigen Phase des zweiten Lanthanoids lösen lassen. Insbesondere sind die Salze Kalziumfluorid oder Neodymfluorid geeignet.A salt that is soluble in the liquid phase of the second lanthanide and combines with it is advantageously used as the added salt that reduces the electrical conductance of the magnetic material. Therefore e.g. B. the oxide of dysprosium or terbium very well suited. In principle, a fluoride can also be suitable as a salt, since fluorides can be easily dissolved in the liquid phase of the second lanthanide. The salts calcium fluoride or neodymium fluoride are particularly suitable.
Ein weiterer Vorteil der Erfindung besteht darin, dass aufgrund der beschriebenen Prozessschritte die Verwendung einer Korngrößenverteilung möglich ist, die zwischen 100 und 300 Mikrometer liegt. Hierunter fallen bevorzugt 80 % der in der Mikrostruktur des entstandenen Werkstoffes vorliegenden Körner des Magnetpulvers.A further advantage of the invention is that, due to the process steps described, it is possible to use a grain size distribution which is between 100 and 300 micrometers. This preferably includes 80% of the grains of the magnetic powder present in the microstructure of the resulting material.
Die Korngrößenverteilung erfolgt durch Siebanalyse. Die Analyse der Kornverteilung in der Mikrostruktur des Magnetwerkstoffes erfolgt durch eine Bildanalyse einer lichtmikroskopischen Aufnahme eines Schliffbildes des Magnetwerkstoffes. Die Bestimmung der Elementverteilung innerhalb der Körner erfolgt durch eine quantifizierte EDX Auswertung auf Basis einer Rasterelektronenmikroskop Auswertung des Schliffbildes.The particle size distribution is determined by sieve analysis. The grain distribution in the microstructure of the magnetic material is analyzed by image analysis of a light micrograph of a micrograph of the magnetic material. The element distribution within the grains is determined by a quantified EDX evaluation based on a scanning electron microscope evaluation of the micrograph.
Ein weiterer Bestandteil der Erfindung ist ein gesinterter, polymerfreier Magnetwerkstoff mit den Merkmalen des Anspruches 10. Dieser weist eine Mikrostruktur auf, die zwischen 60 vol% und 80 vol% Lanthanoid-Eisen-Bor-Körner aufweist. Die Körner weisen dabei in ihrem Kern mindestens 80 at% Eisen und Bor auf. In ihrem Randbereich umfassen die Körner neben dem Eisen und Bor mehr als 50 at% eines ersten Lanthanoids, das dort in erhöhter Konzentration vorliegt. Der Magnetwerkstoff zeichnet sich dadurch aus, dass zwischen den Lanthanoid-FeB-Körnern eine Zwischenphase vorliegt, die zu mehr als 50 at% ein zweites Element aus der Reihe der Lanthanoiden, also ein zweites Lanthanoid aufweist, das eine höhere Ordnungszahl aufweist als das erste Lanthanoid, das in den Körnern vorliegt. Ferner weist diese Zwischenphase ein Salz auf, wobei der elektrische Leitwert des Magnetwerkstoffes weniger als 10 S/m beträgt.Another component of the invention is a sintered, polymer-free magnetic material with the features of
Der beschriebene Magnetwerkstoff weist dieselben vorteilhaften Eigenschaften auf, die bereits bezüglich des Verfahrens zur Herstellung dieses Magnetwerkstoffes beschrieben sind. Insbesondere die Einbringung des zweiten Lanthanoiden in die Zwischenphase, gemeinsam mit dem beschriebenen Salz, führen einerseits zur Erhöhung der dauermagnetischen Eigenschaften bei einer gleichzeitigen Reduktion des elektrischen Leitwertes durch das Salz.The magnetic material described has the same advantageous properties that have already been described with regard to the method for producing this magnetic material. In particular, the introduction of the second lanthanide into the intermediate phase, together with the salt described, leads on the one hand to an increase in the permanent magnetic properties with a simultaneous reduction in the electrical conductance by the salt.
Auch bezüglich des Dauermagneten an sich ist es zweckmäßig, als erstes Lanthanoidelement des Neodyms anzuwenden, das zusammen mit Eisen und Bor einen sehr guten Dauermagneten ergibt. Des Weiteren ist es zweckmäßig, als zweites Lanthanoid das Dysprosium oder das Terbium bzw. Legierungen hieraus anzuwenden, wodurch die magnetischen Eigenschaften noch einmal erhöht werden.Also with regard to the permanent magnet itself, it is expedient to use neodymium as the first lanthanide element, which together with iron and boron results in a very good permanent magnet. Furthermore, it is expedient to use dysprosium or terbium or alloys thereof as the second lanthanide, which increases the magnetic properties even further.
Auch das Oxid des Dysprosiums und des Terbiums, bzw. ein Fluorid des Kalziums oder des Dysprosiums, sind besonders gut geeignet, sich in dem zweiten Lanthanoid zu lösen und dort eine Reduktion des elektrischen Leitwertes zu bewirken.The oxide of dysprosium and terbium, or a fluoride of calcium or dysprosium, are also particularly suitable for dissolving in the second lanthanide and bringing about a reduction in the electrical conductance there.
Besonders bevorzugt zeichnet sich der Magnetwerkstoff durch eine geringe Porosität aus, wobei diese insbesondere weniger als 20 vol% beträgt. Die Porosität wird mittels Quecksilberporosimetrie gemessen.The magnet material is particularly preferably characterized by a low porosity, with this in particular being less than 20 vol%. The porosity is measured by mercury porosimetry.
Weitere vorteilhafte Merkmale und weitere Ausgestaltungsformen der Erfindung werden anhand der folgenden Figuren beschrieben. Dabei handelt es sich um rein schematische Darstellungen, die keine Einschränkung im Schutzbereich darstellen.Further advantageous features and further embodiments of the invention are described with reference to the following figures. These are purely schematic representations that do not represent any restrictions in the scope of protection.
Dabei zeigen:
-
Figur 1 einen schematischen Ablauf des beschriebenen Verfahrens zur Herstellung eines Magnetwerkstoffes -
einen Querschnitt durch ein Korn eines Magnetpulvers undFigur 2 -
Figur 3 eine schematische Darstellung der Mikrostruktur des Magnetwerkstoffes.
-
figure 1 a schematic sequence of the described method for producing a magnetic material -
figure 2 a cross-section through a grain of magnetic powder and -
figure 3 a schematic representation of the microstructure of the magnetic material.
In
Der so entstandene Vorkörper 12 weist somit das Bindemittel 10 und das Magnetpulver 6 auf, wobei in einem weiteren Schritt, einem Entbinderungsschritt 14, in einem Entbinderungsofen 44 bei erhöhter Temperatur, beispielsweise bei 220 °C, das Bindemittel 10 thermisch zersetzt wird und aus dem Vorkörper 12 austritt. Diesen Prozessschritt bezeichnet man als Entbindern.The resulting
Nach dem Entbindern ist der ehemals im Wesentlichen dichte Vorkörper 12 zu einem porösen Vorkörper 16 geworden, da das vormals enthaltene Bindemittel 10 sich thermisch bzw. chemisch zersetzt hat und aus dem Vorkörper 12 ausgetreten ist. Der poröse Vorkörper 16 wird nun einem Infiltrationsschritt zugeführt. Hierbei wird zunächst eine zweite Mischung 18 bereitgestellt, die ein zweites Lanthanoid 20 sowie ein Salz 22 umfasst, die zusammen in ein Lösungsmittel 24 gegeben werden, woraus eine Lösung 26 entsteht. Die Lösung 26 wird über Kapillarkräfte in den porösen Vorkörper 16 infiltriert.After the binder has been removed, the formerly essentially dense
Der Begriff Infiltration ist dabei weitläufig zu verstehen. Grundsätzlich handelt es sich bei der Beschreibung unter Anwendung eines Lösungsmittels um eine beispielhafte, vorteilhafte Ausgestaltungsform. Grundsätzlich könnte auch das Lanthanoid auf eine entsprechende Schmelztemperatur gebracht werden, darin das Salz 22 gelöst werden und bei einem Hochtemperaturprozess eine Infiltration des offenporigen Vorkörpers 16 mit der zweiten Mischung in flüssiger Phase durchgeführt werden. Des Weiteren ist es auch möglich, die zweite Mischung 18 und das Lösungsmittel 24 in der Art zu wählen, dass die Lösung 26 in gasförmiger Form vorliegt und eine Infiltration in Form einer Gasphasenabscheidung, beispielsweise in Form einer chemical wapor deposition (CVD oder CVI), erfolgt.The term infiltration is to be understood broadly. In principle, the description using a solvent is an exemplary, advantageous embodiment. In principle, the lanthanide could also be brought to an appropriate melting temperature, the salt 22 could be dissolved in it and the open-pored
Nach der Infiltration wird von einem infiltrierten Vorkörper 30 gesprochen, der in einem weiteren Prozessschritt, einer Wärmebehandlung 28 in einem Wärmebehandlungsofen 46 bei einer Sintertemperatur zum Magnetwerkstoff 2 gesintert wird. Bei der Wärmehandlung 28 handelt es sich dabei bevorzugt um einen diffusionsgesteuerten Sinter-Prozess, bei dem bevorzugt keine flüssige Phase in der Mikrostruktur eines Sinterkörpers 52 (Übergangszustand zwischen infiltrierter Vorkörper 30 und Magnetwerkstoff 2) während des Prozesses vorliegt. Beispielsweise liegen bei Temperaturen von ca. 1000 °C, bevorzugt in einem Bereich zwischen 800 °C und 1200 °C, je nach verwendeten Komponenten für den Magnetwerkstoff 2, im Sinterkörper 52 Aggregatszustände vor, die zwar flüssige Phasenanteile aufweisen, wobei jedoch bei dem Austausch von Materialien zwischen Körnern 32 Diffusionsprozesse dominieren. Durch derartige diffusionsgesteuerte Prozesse kann eine Mikrostruktur 34, wie sie in
In
Diese guten dauermagnetischen Eigenschaften werden durch eine Mikrostruktur, die in
Die in
Im Gegensatz zum Stand der Technik erweist sich die beschriebene Mikrostruktur 34 als eine typische Mikrostruktur, die durch einen diffusionsgesteuerten Prozess erzielt wird. Würde bei der Herstellung bzw. bei dem Sinterprozess die flüssige Phase dominieren, wie es im Stand der Technik häufig angewendet wird, so würde die Mikrostruktur von Schmelzphasen dominiert werden. Hier liegt jedoch das ursprüngliche Korn 32 nur in leicht modifizierter Form mit einem höheren Anreicherungsgrad von Lanthanoiden im Randbereich 38 vor.In contrast to the prior art, the described
Ferner ist es bei dem beschriebenen Werkstoff 2 und der Mikrostruktur 34 zweckmäßig, dass die verwendeten Körner 32 einen höheren Durchmesser aufweisen als dies im Stand der Technik üblich ist. Körner 32 weisen einen Durchmesser zwischen 100 und 300 Mikrometer, bevorzugt zwischen 150 und 250 Mikrometer auf. Sie sind in der gemäß
- 22
- Magnetwerkstoffmagnet material
- 44
- Mischungmixture
- 66
- Magnetpulvermagnetic powder
- 88th
- erstes Lanthanoidfirst lanthanide
- 1010
- Bindemittelbinder
- 1212
- Vorkörperpre-body
- 1414
- Entbinderungsschrittdebinding step
- 1616
- offenporige Vorkörperopen-pore preforms
- 1818
- zweite Mischungsecond mix
- 2020
- zweites Lanthanoidsecond lanthanide
- 2222
- SalzSalt
- 2424
- Lösungsmittelsolvent
- 2626
- LösungSolution
- 2828
- Wärmebehandlungheat treatment
- 3030
- infiltrierte Vorkörperinfiltrated anterior bodies
- 3232
- Körniges MagnetpulverGranular magnetic powder
- 3434
- Mikrostrukturmicrostructure
- 3636
- Eisen-Bor Phaseiron-boron phase
- 3838
- Randbereichedge area
- 4040
- Zwischenphaseintermediate phase
- 4242
- Formgebungsvorrichtungshaping device
- 4444
- Entbinderungsofendebinding oven
- 4646
- Wärmebehandlungsofenheat treatment furnace
- 4848
- Mischvorrichtungmixing device
- 5050
- Sinterhälsesinter necks
Claims (14)
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Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2043114A1 (en) * | 2006-11-30 | 2009-04-01 | Hitachi Metals, Ltd. | R-Fe-B MICROCRYSTALLINE HIGH-DENSITY MAGNET AND PROCESS FOR PRODUCTION THEREOF |
CN105976959A (en) * | 2016-07-14 | 2016-09-28 | 安徽万磁电子有限公司 | Nickel-plating NdFeB magnet with terbium yttrium ions injected and preparation method of magnet |
WO2017055170A1 (en) * | 2015-09-28 | 2017-04-06 | OBE OHNMACHT & BAUMGäRTNER GMBH & CO. KG | Method for producing a permanent magnet |
WO2021071236A1 (en) * | 2019-10-07 | 2021-04-15 | 주식회사 엘지화학 | Manufacturing method of sintered magnet |
DE102020211857A1 (en) * | 2020-09-22 | 2022-03-24 | Mimplus Technologies Gmbh & Co. Kg | Process for producing a permanent magnet from a magnetic starting material |
-
2022
- 2022-02-09 EP EP22155955.2A patent/EP4227963A1/en active Pending
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2043114A1 (en) * | 2006-11-30 | 2009-04-01 | Hitachi Metals, Ltd. | R-Fe-B MICROCRYSTALLINE HIGH-DENSITY MAGNET AND PROCESS FOR PRODUCTION THEREOF |
WO2017055170A1 (en) * | 2015-09-28 | 2017-04-06 | OBE OHNMACHT & BAUMGäRTNER GMBH & CO. KG | Method for producing a permanent magnet |
CN105976959A (en) * | 2016-07-14 | 2016-09-28 | 安徽万磁电子有限公司 | Nickel-plating NdFeB magnet with terbium yttrium ions injected and preparation method of magnet |
WO2021071236A1 (en) * | 2019-10-07 | 2021-04-15 | 주식회사 엘지화학 | Manufacturing method of sintered magnet |
DE102020211857A1 (en) * | 2020-09-22 | 2022-03-24 | Mimplus Technologies Gmbh & Co. Kg | Process for producing a permanent magnet from a magnetic starting material |
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