EP4244876A1 - Method for producing a permanent magnet from a magnetic starting material - Google Patents

Method for producing a permanent magnet from a magnetic starting material

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Publication number
EP4244876A1
EP4244876A1 EP21814732.0A EP21814732A EP4244876A1 EP 4244876 A1 EP4244876 A1 EP 4244876A1 EP 21814732 A EP21814732 A EP 21814732A EP 4244876 A1 EP4244876 A1 EP 4244876A1
Authority
EP
European Patent Office
Prior art keywords
hydrogen
starting material
raw
predetermined
magnetic
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.)
Pending
Application number
EP21814732.0A
Other languages
German (de)
French (fr)
Inventor
Johannes MAURATH
Simone Schuster
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mimplus Technologies & Co Kg GmbH
Original Assignee
Mimplus Technologies & Co Kg GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mimplus Technologies & Co Kg GmbH filed Critical Mimplus Technologies & Co Kg GmbH
Publication of EP4244876A1 publication Critical patent/EP4244876A1/en
Pending legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/06—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder
    • H01F1/08—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together
    • H01F1/086—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together sintered
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/10—Sintering only
    • B22F3/1003—Use of special medium during sintering, e.g. sintering aid
    • B22F3/1007—Atmosphere
    • 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
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/12—Both compacting and sintering
    • B22F3/14—Both compacting and sintering simultaneously
    • B22F3/15—Hot isostatic pressing
    • 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
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
    • H01F41/0273—Imparting anisotropy
    • 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
    • B22F2201/00—Treatment under specific atmosphere
    • B22F2201/10—Inert gases
    • 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
    • B22F2301/00—Metallic composition of the powder or its coating
    • B22F2301/35—Iron
    • B22F2301/355—Rare Earth - Fe intermetallic alloys
    • 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
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • B22F2998/10—Processes characterised by the sequence of their steps
    • 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
    • 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
    • H01F1/0573—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 obtained by reduction or by hydrogen decrepitation or embrittlement
    • 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
    • H01F1/0576—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 pressed, e.g. hot working

Definitions

  • the invention relates to a method for producing a permanent magnet from a magnetic starting material.
  • Permanent magnets from the rare earth group are used in a variety of technical applications and are characterized by a particularly high energy product.
  • Neodymium-iron-boron magnets in particular have an energy product of up to 400 kJ/m 3 .
  • the permanent magnets installed there are cyclically exposed to an oppositely directed magnetic field during operation. To ensure proper operation, the permanent magnets must maintain their magnetic flux density and magnetic alignment.
  • a permanent magnet has the highest possible coercive field strength.
  • the coercive field strength indicates how strong an opposing magnetic field to which the permanent magnet is exposed can be in order to prevent permanent damage to the permanent magnet.
  • Permanent magnets from the group of rare earths in particular neodymium-iron-boron magnets, have a temperature-dependent remanence and a temperature-dependent coercive field strength, with both the remanence and the coercive field strength decreasing with increasing temperature. Since the coercive field strength drops significantly more than the remanence with increasing temperature, in industrial applications, especially in Applications in which high temperatures can occur, especially in electric motors, preferably used permanent magnets with a high coercivity.
  • a first possibility for increasing the coercive field strength consists in an addition of at least one additional rare earth element, in particular at least one “heavy” rare earth element, such as dysprosium and/or terbium.
  • the disadvantage of this is that these elements are very expensive and also reduce the remanence of the permanent magnet at the same time.
  • a second possibility for increasing the coercive field strength in relation to a comparable permanent magnet consists in the production of a microstructure which is designed with finer grains than in the case of the comparable permanent magnet.
  • Such a structure can be realized in particular by using a starting powder that is finer-grained than a starting powder of the comparable permanent magnet.
  • the disadvantage of this is that such a fine-grained powder, in particular with a grain size ⁇ 5 ⁇ m, is very difficult to produce in terms of process technology and is very difficult to process, especially since the fine-grained powder oxidizes easily and thus becomes unusable.
  • a third possibility to increase the coercive field strength is a suitable heat treatment, especially in the case of permanent magnets which are manufactured by means of sintering.
  • the disadvantage of this is that the coercive field strength can only be increased to a very limited extent.
  • the invention is therefore based on the object of creating a method for producing a permanent magnet from a magnetic starting material, the disadvantages mentioned being at least partially eliminated, preferably avoided.
  • the object is achieved in particular by creating a method for producing a permanent magnet from a magnetic starting material, the magnetic starting material being shaped, with a raw mold being created.
  • a grain refinement is carried out on the raw form.
  • the raw form undergoes grain refinement subjected.
  • the raw form is then sintered, producing the permanent magnet.
  • a very fine-grained structure is advantageously created by means of grain refinement. It is particularly advantageous that the fine-grain structure is created in the raw form, in particular directly before sintering. It is thus possible to produce a permanent magnet with a very fine grain structure and a very high coercivity in a simple manner and without the risk that the starting material used will become unusable, in particular due to oxidation.
  • the method is advantageously suitable for a powdered magnetic starting material which is formed on the basis of a newly melted alloy, in particular in the form of a cast block or in the form of melt-spun material.
  • the method is suitable for recycled magnetic material and/or for contaminated recycled magnetic material.
  • material obtained by recycling is preferably alloyed with at least one rare earth element, preferably in powder form, to improve its properties.
  • the magnetic starting material is preferably in a pure form or in a hydrogenated form.
  • US patent application US 2013/0263699 A1 and German patent DE 198 43 883 CI describe a process called hydrogen decrepitation (HD) for producing a hydrogenated form of the magnetic starting material by means of hydrogen-induced decay.
  • HD hydrogen decrepitation
  • the magnetic starting material is preferably comminuted mechanically, in particular by grinding, to a particle size of 1 ⁇ m to 200 ⁇ m in order to obtain the magnetic starting material in powder form.
  • a material which has particles of an R x T y B alloy is used as the magnetic starting material.
  • a material consisting of particles of an R x T y B alloy is preferably used as the magnetic starting material.
  • a material which has particles of an Nd x Fe y B alloy or consists of particles of an Nd x Fe y B alloy is preferably used as the magnetic starting material.
  • a material which has particles of an R x T y B alloy and particles of a phase rich in rare earths is preferably used as the magnetic starting material.
  • the magnetic source material preferably consists of a mixture of R x TyB alloy particles and rare earth-rich phase particles.
  • a material which has particles of an Nd x Fe y B alloy and particles of a neodymium-rich phase or consists of such particles is preferably used as the magnetic starting material.
  • the magnetic starting material preferably has a mixture of particles of an Nd x Fe y B alloy and particles of a neodymium-rich phase or consists of such a mixture.
  • R is a rare earth element
  • T is at least one element selected from a group consisting of iron and cobalt
  • B is the element boron.
  • the elements iron and cobalt partially or partially substitute each other completely such that either only iron or only cobalt or any iron-cobalt mixture is present.
  • the rare earth element is neodymium.
  • the R x T y B alloy additionally comprises a further element, preferably a metal, in particular a transition metal selected from a group consisting of aluminum, copper, zirconium, gallium, hafnium and niobium, preferably in traces.
  • the magnetic starting material preferably has particles of an Nd2Fei4B alloy or consists of particles of an Nd2Fei4B alloy.
  • the rare earth-rich phase in particular the neodymium-rich phase, preferably has at least one rare earth element, in particular neodymium, or a chemical compound of this rare earth element, in particular neodymium.
  • the rare earth-rich phase, in particular the neodymium-rich phase preferably contains at least one further element of the R x T y B alloy, in particular the Nd x Fe y B alloy.
  • the at least one rare earth element, in particular neodymium is in a hydrogenated form.
  • the neodymium-rich phase preferably has NdH2 and/or NdH2.7 or consists of NdH2 and/or NdH2.7.
  • the rare earth-rich phase in particular the neodymium-rich phase, consists of at least one rare earth element, in particular neodymium, or a chemical compound of this rare earth element, in particular of neodymium.
  • the phase rich in rare earths preferably forms a phase in the structure of the permanent magnet that is located at grain boundaries of the structure.
  • the magnetic starting material is mixed with an organic binder, with a mixture of the magnetic starting material and the organic binder being obtained.
  • the raw form is created from the mixture, with the organic binder being at least partially removed from the raw form before grain refinement.
  • the organic binder is preferably completely removed from the raw form before grain refinement.
  • the magnetic starting material preferably in powder form, is advantageously mixed with the organic binder. Furthermore, the molding of the raw form from the mixture is possible in a simple manner.
  • the organic binder is in a hydrogen atmosphere or a hydrogen inert gas atmosphere at a pressure of at least 50 mbar absolute to at most 100 mbar above atmospheric pressure, preferably at 50 mbar above atmospheric pressure, at least partially, preferably completely from the Rough form removed.
  • the raw mold is heated to a temperature of at least 350 °C and at most 650 °C at a heating rate of at least 0.1 K/min and at most 10 K/min.
  • a holding stage is preferably provided at at least one predetermined temperature; in particular, holding stages are installed at a plurality of predetermined temperatures, with the temperature being maintained at the at least one holding stage for a predetermined period of time, preferably from at least 30 minutes to a maximum of 300 minutes will.
  • a preferred soak stage maintains a temperature of 600°C for a period of 180 minutes.
  • pure heating without holding stages lasts at least 35 minutes to at most 6500 minutes, in particular depending on the heating rate and the temperature to which the raw mold is heated.
  • the duration of the complete process for removing the organic binder from the raw mold in a preferred embodiment results from the selected heating rate, the temperature to which the raw mold is heated, and a number and a respective duration of the holding stages.
  • the organic binder is at least partially, preferably completely removed from the raw form in an inert gas atmosphere at a pressure of at least 10′5 mbar absolute to at most 100 mbar above atmospheric pressure, preferably at 50 mbar above atmospheric pressure.
  • the raw mold is heated to a temperature of at least 350° C. at a heating rate of at least 0.1 K/min and at most 10 K/min heated to a maximum of 650 °C.
  • a holding stage is preferably provided at at least one predetermined temperature, in particular holding stages are installed at a plurality of predetermined temperatures, the temperature at the at least one holding stage being maintained for a predetermined period.
  • a preferred soak stage maintains a temperature of 600°C for a period of 180 minutes.
  • the complete process for removing the organic binder from the raw form lasts at least 30 minutes and at most 300 minutes.
  • the raw form can be exposed to an atmosphere containing hydrogen, in particular in a hydrogen atmosphere, in particular in pure hydrogen, preferably at a pressure of at least 50 mbar absolute to at most 50 mbar above atmospheric pressure, at a temperature of at least 600°C and at most 900°C, preferably for a period of at least 30 minutes and at most 180 minutes.
  • an atmosphere containing hydrogen in particular in a hydrogen atmosphere, in particular in pure hydrogen, preferably at a pressure of at least 50 mbar absolute to at most 50 mbar above atmospheric pressure, at a temperature of at least 600°C and at most 900°C, preferably for a period of at least 30 minutes and at most 180 minutes.
  • a hydrogen atmosphere is understood to mean, in particular, a gas which consists of pure hydrogen and impurities of at most 5% by volume.
  • the magnetic starting material is mixed with an organic solvent, a mixture of the magnetic starting material and the organic solvent being obtained.
  • the raw form is created from the mixture, with the organic solvent being at least partially removed from the raw form before grain refinement.
  • the organic solvent is preferably completely removed from the raw form before grain refinement.
  • the magnetic starting material preferably in powder form, is mixed with the organic solvent. Furthermore, the molding of the raw form from the mixture is possible in a simple manner.
  • the organic solvent is heated at a maximum temperature of 250° C. and/or under vacuum, in particular at a pressure of at least 10'5 mbar absolute to a maximum of 800 mbar absolute, for a period of at least 30 minutes to a maximum of 180 minutes evaporated.
  • the grain refinement has a hydrogen storage step and a recombination step—following the hydrogen storage step.
  • the raw form particularly the particles of the magnetic source material constituting the raw form, is reacted with hydrogen.
  • the hydrogen is at least partially, preferably completely, withdrawn from the raw form.
  • the neodymium-iron-boron grains present in the neodymium-rich phase react with the hydrogen and result in the formation of a neodymium-hydrogen phase, an iron phase and an iron-boron phase.
  • the neodymium-hydrogen phases, the iron phases and the iron-boron phases are present in particular in addition to the neodymium-iron-boron phases, ie the reaction according to equation (1) does not proceed quantitatively.
  • the neodymium-hydrogen phases, the iron phases and the iron-boron phases form as small, finely divided islands in the initial neodymium-iron-boron grain.
  • the grain therefore does not disintegrate and, in particular, remains dimensionally stable.
  • the raw form remains dimensionally stable.
  • a reverse reaction of the chemical reaction (1) advantageously takes place during the recombination step.
  • reaction (2) at least partially, preferably completely, removed, ie the reaction according to equation (2) preferably proceeds quantitatively.
  • the small, finely divided islands of neodymium-hydrogen phases, iron phases, and iron-boron phases formed in chemical reaction (1) become small grains of neodymium Iron-boron phase merged.
  • the neodymium-iron-boron phase which forms the educt of the chemical reaction (1), differs from the neodymium-iron-boron phase, which forms the product of the chemical reaction (2), in the grain size of the respective phase .
  • the neodymium Iron-boron grains after the recombination step, especially after the chemical reaction (2), are smaller than the neodymium-iron-boron grains before the hydrogen occlusion step, especially before the chemical reaction (1).
  • the magnetic axis of the neodymium-iron-boron grains remains almost identical, preferably completely identical.
  • the hydrogen storage step is carried out in an atmosphere containing hydrogen under a predetermined storage s pressure for a predetermined storage period. Furthermore, during the hydrogen incorporation step, the green form is heated to a predetermined incorporation s temperature.
  • the predetermined storage pressure is at least 50 mbar absolute to at most 50 mbar above atmospheric pressure.
  • the predetermined storage period is preferably at least 30 minutes to at most 300 minutes.
  • the predetermined storage s temperature is preferably at least 750° C. to at most 900° C. and is achieved in particular by means of a heating rate of at least 0.1 K/min to at most 10 K/min, preferably 3 K/min.
  • the hydrogen storage step is carried out in an atmosphere consisting of hydrogen, in particular in a hydrogen atmosphere or in pure hydrogen.
  • the hydrogen storage step is carried out in an atmosphere which has hydrogen and at least one inert gas, in particular selected from argon and helium, preferably consists of hydrogen and at least one inert gas, in particular selected from argon and helium.
  • the atmosphere in which the hydrogen storage step is carried out preferably has at least 60% by volume hydrogen and at least one inert gas, in particular selected from argon and helium, or it consists of at least 60% by volume hydrogen and at least one inert gas , in particular selected from argon and helium.
  • the hydrogen storage step is particularly preferably carried out in a hydrogen atmosphere, in particular in pure hydrogen.
  • the recombination step is carried out in an atmosphere containing a process gas or consisting of the process gas under a predetermined recombination pressure and a predetermined recombination temperature for a predetermined recombination duration.
  • the predetermined recombination temperature is at least 750°C to at most 900°C.
  • the predetermined recombination duration is preferably at least 30 minutes to at most 300 minutes.
  • the predetermined recombination pressure is at least 10′ 5 mbar absolute and at most 10′ 3 mbar absolute.
  • the predetermined recombination temperature is at least 750°C and at most 900°C.
  • the recombination step is carried out for the predetermined recombination duration of at least 30 minutes and at most 300 minutes.
  • the process gas is selected from a group consisting of hydrogen, argon and helium.
  • the predetermined recombination pressure is at least 10'3 mbar absolute up to at most 900 mbar absolute, particularly preferably up to at most 200 mbar absolute, the atmosphere containing the process gas hydrogen.
  • the atmosphere in which the recombination step is carried out has at most 40% by volume, preferably at most 20% by volume, hydrogen and at least one inert gas, in particular selected from argon and helium, or the atmosphere consists of at most 40 % by volume, preferably at most 20% by volume, hydrogen and at least one inert gas, in particular selected from argon and helium.
  • the atmosphere in which the recombination step is carried out has in particular at least 60% by volume, preferably at least 80% by volume, inert gas, with the volume fractions of all inert gases in the atmosphere being added up for this purpose.
  • the recombination step is carried out in a hydrogen atmosphere or in pure hydrogen.
  • the predetermined recombination temperature is at least 750°C and at most 900°C. The recombination step is carried out for the predetermined recombination duration of at least 30 minutes and at most 300 minutes.
  • the predetermined recombination pressure is at least 10'3 mbar absolute to at most 50 mbar above atmospheric pressure, the atmosphere consisting of the process gas argon and/or helium.
  • the predetermined recombination temperature is at least 750°C and at most 900°C. The recombination step is carried out for the predetermined recombination duration of at least 30 minutes and at most 300 minutes.
  • the raw mold is cooled to a predetermined cooling temperature during or after the recombination step.
  • the raw form is produced by means of a method selected from a group consisting of injection molding, in particular metal powder injection molding, additive manufacturing, extrusion, cold pressing and hot pressing.
  • the raw form is produced by injection molding a mixture comprising the magnetic starting material and the organic binder.
  • the raw form is produced by cold pressing a magnetic starting material.
  • the particles are mechanically interlocked, in particular under a pressure of up to 1 GPa.
  • dry cold pressing in particular, no additional liquid component is added to the magnetic starting material.
  • wet cold pressing an organic solvent, preferably a volatile non-polar and/or polar organic solvent, is added to the magnetic starting material.
  • the volatile non-polar and/or polar organic solvent is selected from a group consisting of an alcohol, an acyclic alkane, a cyclic alkane, a ketone, and a mixture of volatile organic substances that can serve as a solvent. Ethanol or isopropanol is preferably used as the alcohol.
  • Cyclohexane is preferably used as the cyclic alkane.
  • Acetone is preferably used as the ketone.
  • the mixture of volatile organic substances is preferably selected from a group consisting of petroleum, mineral spirits, and mineral spirits.
  • the organic solvent serves in particular as a binder in wet cold pressing.
  • the raw form is preferably dried before sintering.
  • the raw form is produced by hot pressing a magnetic starting material. During hot pressing, the particles are in particular mechanically interlocked and/or cold-welded.
  • the raw mold is produced in an externally applied magnetic field. Dipoles of the magnetic starting material are advantageously aligned in a parallel orientation by means of the externally applied magnetic field during the production of the raw form.
  • the externally applied magnetic field is preferably generated by a switchable electromagnet and/or a permanent magnet.
  • the raw form is sintered at a predetermined sintering pressure and at a predetermined sintering temperature, preferably a temperature of at least 900° C. to at most 1200° C., in an atmosphere consisting of a process gas for a predetermined sintering - Duration is sintered.
  • the predetermined sintering time is preferably at least 30 minutes and at most 240 minutes.
  • the predetermined sintering pressure is at least 10'5 mbar absolute to at most 50 mbar above atmospheric pressure.
  • the process gas is selected from a group consisting of argon and helium.
  • the raw mold is made in an atmosphere consisting of argon and/or helium at a predetermined sintering pressure of at least 10'5 mbar absolute to at most 50 mbar above atmospheric pressure and at a predetermined sintering temperature of at least 1000 °C up to a maximum of 1200 °C for a predetermined sintering time of at least 30 minutes and at most 240 minutes.
  • the raw mold is made in an atmosphere consisting of argon and/or helium at a predetermined sintering pressure of at least 10'5 mbar absolute to at most 50 mbar above atmospheric pressure and at a predetermined sintering temperature of at least 900°C to a maximum of 1000°C for a predetermined sintering time of a minimum of 30 minutes to a maximum of 240 minutes.
  • a predetermined sintering pressure of at least 10'5 mbar absolute to at most 50 mbar above atmospheric pressure and at a predetermined sintering temperature of at least 900°C to a maximum of 1000°C for a predetermined sintering time of a minimum of 30 minutes to a maximum of 240 minutes.
  • the hot isostatic pressing is carried out at a pressure of at least 800 bar to a maximum of 2000 bar and a temperature of at least 900° C. to a maximum of 1200° C. for a period of at least 30 minutes to a maximum of 240 minutes.
  • the sintered raw form is subjected to an additional heat treatment.
  • Processes for heat treatment are known from the prior art and enable an additional increase in the coercive field strength of the permanent magnet, which is produced by sintering the raw form.
  • the invention also includes a permanent magnet which is produced by means of a method according to the invention or by means of a method according to one or more of the embodiments described above.
  • the invention also includes use of such a permanent magnet in a device selected from a group consisting of an electric motor, a loudspeaker, a microphone, a generator, a hard disk drive and a sensor.
  • the invention also includes a device selected from a group consisting of an electric motor, a loudspeaker, a microphone, a generator, a hard disk drive, and a sensor, the device having a permanent magnet which is activated by a method according to the invention or a method according to a or more of the embodiments described above is provided.
  • FIG. 1 shows a flow chart of a method for producing a permanent magnet
  • FIG. 2 shows a schematic representation of an embodiment of grain refinement in a first exemplary embodiment of a raw mold
  • 3 shows a schematic representation of a second exemplary embodiment of a raw mold.
  • FIG. 1 shows a flow chart of a method for manufacturing a permanent magnet.
  • the magnetic starting material preferably in powder form, is made available.
  • the powdery magnetic raw material is obtained by grinding an ingot, a melt-spun material, or a recycled magnetic material.
  • the starting material is embrittled by hydrogen embrittlement prior to milling.
  • the magnetic source material comprises particles of an R x T y B alloy, preferably a Nd2Fei4B alloy, and preferably particles of a rare earth-rich phase.
  • the magnetic starting material is shaped, with a raw form 1 shown in FIG. 2a) being created.
  • the raw mold 1 is preferably produced by a method selected from a group consisting of injection molding, additive manufacturing, extrusion, cold pressing, and hot pressing.
  • the production of the raw mold 1 is carried out under an externally applied magnetic field.
  • the magnetic field is preferably generated by a switchable electromagnet and/or a permanent magnet.
  • step c) grain refinement is carried out on the raw mold 1 .
  • the process step of grain refinement preferably has a hydrogen storage step, in particular step c1), and a recombination step, in particular step c2).
  • the raw mold 1, particularly the particles of the magnetic raw material constituting the raw mold 1 are reacted with hydrogen.
  • the hydrogen charging step is performed in an atmosphere containing hydrogen under a predetermined storage pressure for a predetermined storage period.
  • the green mold 1 is heated to a predetermined storage s temperature.
  • the hydrogen is preferably withdrawn from the raw form 1 at least partially, preferably completely.
  • the recombination step is carried out in an atmosphere comprising or consisting of a process gas, preferably hydrogen, argon, and/or helium, under a predetermined recombination pressure and a predetermined recombination temperature for a predetermined recombination period is performed.
  • the raw form 1 is cooled to a predetermined cooling temperature during or after the recombination step, in particular during or after step c2).
  • the raw form 1 is sintered, the permanent magnet being produced.
  • the raw mold 1 is at a predetermined sintering pressure, preferably at least 10' 5 mbar absolute to a maximum of 50 mbar above atmospheric pressure, at a predetermined sintering temperature, preferably at a temperature of at least 900 ° C to a maximum of 1200 ° C, in a an atmosphere consisting of a process gas, preferably argon and/or helium, for a predetermined sintering time, preferably at least 30 minutes to a maximum of 240 minutes.
  • Process step e) can optionally be carried out between step a) and step b).
  • the magnetic base material is mixed with an organic binder or an organic solvent to obtain a mixture of the magnetic base material and the organic binder or the organic solvent.
  • the raw mold 1 is created from the mixture in step b).
  • An organic binder is preferably used if the raw mold 1 is produced by injection molding.
  • An organic solvent is preferably used if the raw mold 1 is produced by wet cold pressing.
  • step f) must be carried out between step b) and step c).
  • step f) the organic binder or the organic solvent which was added to the magnetic starting material in step e) is at least partially, preferably completely, removed.
  • an additional process step g) can be carried out between step b) and step c) or between step f) and step c).
  • the raw form is exposed in an atmosphere containing hydrogen, in particular a hydrogen atmosphere or in pure hydrogen, preferably at a pressure of at least 50 mbar absolute to at most 50 mbar above atmospheric pressure, and preferably at a temperature of at least 600° C. to at most 900 °C, preferably for a period of at least 30 minutes to at most 180 minutes.
  • an additional process step h) - individually or in combination with the process steps e), f) and g) - be carried out.
  • step h) the sintered raw form 1 is post-treated by means of hot isostatic pressing in order to post-compact the permanent magnet.
  • the hot isostatic pressing is carried out at a pressure of preferably at least 800 bar to a maximum of 2000 bar and a temperature of preferably at least 900° C. to a maximum of 1200° C. for a period of preferably at least 30 minutes to a maximum of 240 minutes.
  • the second shows a schematic representation of an embodiment of grain refinement in a first embodiment of a raw mold 1.
  • the first embodiment of a raw mold 1 has particles of an Nd2Fei4B alloy.
  • FIG. 2 a) shows a section 3 from a single large Nd2Fei4B grain 5 as part of the magnetic starting material.
  • the Nd2Fei4B-Com 5 has a magnetic axis 7 .
  • the raw mold 1 shown in FIG. 2a) is subjected to a hydrogen storage step. In this case, hydrogen is stored in the raw form 1 and the particles of the Nd2Fei4B alloy, in particular the Nd2Fei4B grain 5 shown, are split according to the chemical reaction (1).
  • FIG. 2 b) shows section 3 after the chemical reaction (1), in particular after the hydrogen storage step.
  • the Nd2Fei4B grain 5 was split into a plurality of NdHx grains 9, a plurality of Fe grains 11, a plurality of Fe2B grains 13 and a plurality of Nd2Fei4B grains 15. Only the majority of Nd2Fei4B grains 15 have the magnetic axis 7 .
  • the plurality of NdH x grains 9, the plurality of Fe grains 11, and the plurality of Fe2B grains 13 have no magnetic axis.
  • the NdH x grains 9, the Fe grains 11, the Fe2B grains 13 and the Nd2Fei4B grains 15 are each smaller than the initial Nd2Fei4B grain 5.
  • the raw form 1 from FIG. 2 b) is subjected to a recombination step, in which the hydrogen is at least partially, preferably completely, withdrawn from the raw form 1 .
  • the recombination step occurs according to the chemical reaction (2).
  • FIG. 2 c) shows section 3 after the chemical reaction (2), in particular after the recombination step.
  • the individual are stored Grains of the plurality of NdH x grains 9, the plurality of Fe grains 11, the plurality of Fe2B grains 13 and the plurality of Nd2Fei4B grains 15 together and form another plurality of new Nd2Fei4B grains 17.
  • Each grain of the plurality of Nd2Fei4B grains 17 has the magnetic axis 7.
  • a grain 17 and a magnetic axis 7 are provided with a reference number.
  • the Nd2Fei4B grains 17 are advantageously each smaller than the initial Nd2Fei4B grain 5 from FIG. 2a).
  • the magnetic axis 7—or the sum of the magnetic axes 7— is almost unchanged before, during and after the grain refinement, as shown in FIG.
  • Fig. 3 shows a schematic representation of a second embodiment of a raw form 1.
  • the raw form 1 consists of Nd2Fei4B grains 5, 17 and a plurality of particles 19 of a rare earth-rich phase, preferably a neodymium-rich phase, which is preferably a hydride present.
  • the magnetic axes 7 of the Nd2Fei4B grains 5, 17 have almost the identical direction.
  • an Nd2Fei4B grain 5, 17, a rare earth-rich particle 19 and a magnetic axis 7 are provided with a reference number.

Abstract

The invention relates to a method for producing a permanent magnet from a magnetic starting material, wherein – the magnetic starting material is brought into shape, wherein a blank (1) is produced, – the blank (1) is subjected to a grain refining, – the blank (1) is sintered, wherein the permanent magnet is produced.

Description

Verfahren zur Herstellung eines Permanentmagneten aus einem magnetischen Ausgangsmaterial Process for producing a permanent magnet from a magnetic starting material
Die Erfindung betrifft ein Verfahren zur Herstellung eines Permanentmagneten aus einem magnetischen Ausgangsmaterial. The invention relates to a method for producing a permanent magnet from a magnetic starting material.
Permanentmagnete aus der Gruppe der Seltenen Erden werden in einer Vielzahl von technischen Anwendungen eingesetzt und zeichnen sich durch ein besonders hohes Energieprodukt aus. Insbesondere Neodym-Eisen-Bor-Magnete weisen ein Energieprodukt von bis zu 400 kJ/m3 auf. Permanent magnets from the rare earth group are used in a variety of technical applications and are characterized by a particularly high energy product. Neodymium-iron-boron magnets in particular have an energy product of up to 400 kJ/m 3 .
Insbesondere bei industriellen Anwendungen ist eine Anforderung an Permanentmagnete, dass die Remanenz dieser Permanentmagnete auch bei einem entgegengesetzt gerichteten magnetischen Feld nicht bleibend abgeschwächt wird. Insbesondere bei Elektromotoren werden die dort verbauten Permanentmagnete während des Betriebs zyklisch einem entgegengesetzt gerichteten magnetischen Feld ausgesetzt. Um einen fehlerfreien Betrieb sicherzustellen, müssen die Permanentmagnete ihre magnetische Flussdichte und ihre magnetische Ausrichtung beibehalten. A requirement for permanent magnets, particularly in industrial applications, is that the remanence of these permanent magnets is not permanently weakened even in the event of a magnetic field directed in the opposite direction. In electric motors in particular, the permanent magnets installed there are cyclically exposed to an oppositely directed magnetic field during operation. To ensure proper operation, the permanent magnets must maintain their magnetic flux density and magnetic alignment.
Darüber hinaus ist es bei industriellen Anwendungen vorteilhaft, wenn ein Permanentmagnet eine möglichst hohe Koerzitivfeldstärke aufweist. Die Koerzitivfeldstärke gibt an, wie stark ein entgegengesetzt gerichtetes magnetisches Feld, welchem der Permanentmagnet ausgesetzt ist, sein darf, um eine bleibende Schädigung des Permanentmagneten auszuschließen. In addition, it is advantageous in industrial applications if a permanent magnet has the highest possible coercive field strength. The coercive field strength indicates how strong an opposing magnetic field to which the permanent magnet is exposed can be in order to prevent permanent damage to the permanent magnet.
Permanentmagnete aus der Gruppe der Seltenen Erden, insbesondere Neodym-Eisen-Bor- Magnete, weisen eine temperaturabhängige Remanenz und eine temperaturabhängige Koerzitivfeldstärke auf, wobei sowohl die Remanenz als auch die Koerzitivfeldstärke bei steigender Temperatur sinken. Da die Koerzitivfeldstärke mit steigender Temperatur deutlich stärker sinkt als die Remanenz, werden bei industriellen Anwendungen, vor allem bei Anwendungen, bei denen hohe Temperaturen auftreten können, insbesondere bei Elektromotoren, bevorzugt Permanentmagnete mit einer hohen Koerzitivfeldstärke eingesetzt. Permanent magnets from the group of rare earths, in particular neodymium-iron-boron magnets, have a temperature-dependent remanence and a temperature-dependent coercive field strength, with both the remanence and the coercive field strength decreasing with increasing temperature. Since the coercive field strength drops significantly more than the remanence with increasing temperature, in industrial applications, especially in Applications in which high temperatures can occur, especially in electric motors, preferably used permanent magnets with a high coercivity.
Eine erste Möglichkeit zur Erhöhung der Koerzitivfeldstärke besteht in einer Zulegierung von mindestens einem zusätzlichen Seltene-Erden-Element, insbesondere mindestens einem „schweren“ Seltene-Erden-Element, wie beispielsweise Dysprosium und/oder Terbium. Nachteilig daran ist, dass diese Elemente sehr teuer sind und zudem gleichzeitig die Remanenz des Permanentmagneten herab setzen. A first possibility for increasing the coercive field strength consists in an addition of at least one additional rare earth element, in particular at least one “heavy” rare earth element, such as dysprosium and/or terbium. The disadvantage of this is that these elements are very expensive and also reduce the remanence of the permanent magnet at the same time.
Eine zweite Möglichkeit zur Erhöhung der Koerzitivfeldstärke in Bezug auf einen vergleichbaren Permanentmagneten besteht in der Herstellung eines Gefüges, welches feinkörniger ausgestaltet ist als bei dem vergleichbaren Permanentmagneten. Ein solches Gefüge kann insbesondere mittels des Einsatzes eines Ausgangspulvers realisiert werden, welches feinkörniger ist als ein Ausgangspulver des vergleichbaren Permanentmagneten. Nachteilig daran ist, dass ein solch feinkörnigeres Pulver, insbesondere mit einer Korngröße < 5 pm, zum einen verfahrenstechnisch sehr schwierig herzustellen und zum anderen sehr schwierig zu verarbeiten ist, insbesondere da das feinkörnige Pulver leicht oxidiert und damit unbrauchbar wird. A second possibility for increasing the coercive field strength in relation to a comparable permanent magnet consists in the production of a microstructure which is designed with finer grains than in the case of the comparable permanent magnet. Such a structure can be realized in particular by using a starting powder that is finer-grained than a starting powder of the comparable permanent magnet. The disadvantage of this is that such a fine-grained powder, in particular with a grain size <5 μm, is very difficult to produce in terms of process technology and is very difficult to process, especially since the fine-grained powder oxidizes easily and thus becomes unusable.
Eine dritte Möglichkeit zur Erhöhung der Koerzitivfeldstärke ist eine geeignete Wärmebehandlung, insbesondere bei Permanentmagneten, welche mittels Sintern hergestellt werden. Nachteilig daran ist, dass damit die Koerzitivfeldstärke nur in einem sehr eingeschränkten Maße erhöht werden kann. A third possibility to increase the coercive field strength is a suitable heat treatment, especially in the case of permanent magnets which are manufactured by means of sintering. The disadvantage of this is that the coercive field strength can only be increased to a very limited extent.
Der Erfindung liegt daher die Aufgabe zugrunde, ein Verfahren zur Herstellung eines Permanentmagneten aus einem magnetischen Ausgangsmaterial zu schaffen, wobei die genannten Nachteile zumindest teilweise behoben, vorzugsweise vermieden sind. The invention is therefore based on the object of creating a method for producing a permanent magnet from a magnetic starting material, the disadvantages mentioned being at least partially eliminated, preferably avoided.
Die Aufgabe wird gelöst, indem die vorliegende technische Lehre bereitgestellt wird, insbesondere die Lehre der unabhängigen Ansprüche sowie der in den abhängigen Ansprüchen und der Beschreibung offenbarten Ausführungsformen. The object is achieved by providing the present technical teaching, in particular the teaching of the independent claims and the embodiments disclosed in the dependent claims and the description.
Die Aufgabe wird insbesondere gelöst, indem ein Verfahren zur Herstellung eines Permanentmagneten aus einem magnetischen Ausgangsmaterial geschaffen wird, wobei das magnetische Ausgangsmaterial in Form gebracht wird, wobei eine Rohform erstellt wird. An der Rohform wird eine Kornfeinung durchgeführt. Insbesondere wird die Rohform einer Kornfeinung unterzogen. Anschließend wird die Rohform gesintert, wobei der Permanentmagnet hergestellt wird. The object is achieved in particular by creating a method for producing a permanent magnet from a magnetic starting material, the magnetic starting material being shaped, with a raw mold being created. A grain refinement is carried out on the raw form. In particular, the raw form undergoes grain refinement subjected. The raw form is then sintered, producing the permanent magnet.
Vorteilhafterweise wird mittels der Kornfeinung ein sehr feinkörniges Gefüge erstellt. Besonders vorteilhaft ist, dass das feinkörnige Gefüge in der Rohform, insbesondere direkt vor dem Sintern, erstellt wird. Damit ist es möglich, einen Permanentmagneten mit einer sehr feinen Komstruktur und einer sehr hohen Koerzitivfeldstärke auf einfache Weise und ohne die Gefahr, dass das verwendete Ausgangsmaterial insbesondere durch Oxidation unbrauchbar wird, zu erzeugen. A very fine-grained structure is advantageously created by means of grain refinement. It is particularly advantageous that the fine-grain structure is created in the raw form, in particular directly before sintering. It is thus possible to produce a permanent magnet with a very fine grain structure and a very high coercivity in a simple manner and without the risk that the starting material used will become unusable, in particular due to oxidation.
Vorteilhafterweise eignet sich das Verfahren für ein pulverförmiges magnetisches Ausgangsmaterial, welches auf Basis einer neu erschmolzenen Legierung, insbesondere in Form eines Gussblocks oder in Form von schmelzgesponnenem Material, gebildet ist. Alternativ oder zusätzlich eignet sich das Verfahren für recyceltes magnetisches Material und/oder für kontaminiertes recyceltes magnetisches Material. Zusätzlich wird Material, welches mittels Recyclings gewonnen wird, zur Verbesserung seiner Eigenschaften vorzugsweise mit mindestens einem Seltene-Erden-Element, vorzugsweise in Pulverform, auflegiert. The method is advantageously suitable for a powdered magnetic starting material which is formed on the basis of a newly melted alloy, in particular in the form of a cast block or in the form of melt-spun material. Alternatively or additionally, the method is suitable for recycled magnetic material and/or for contaminated recycled magnetic material. In addition, material obtained by recycling is preferably alloyed with at least one rare earth element, preferably in powder form, to improve its properties.
Das magnetische Ausgangsmaterial liegt bevorzugt in einer reinen Form oder in einer hydrierten Form vor. Die US-amerikanische Patentanmeldung US 2013/0263699 Al und das deutsche Patent DE 198 43 883 CI beschreiben ein Verfahren, genannt hydrogen decrepitation (HD) , zur Herstellung einer hydrierten Form des magnetischen Ausgangsmaterials mittels eines wasserstoffinduzierten Verfalls. The magnetic starting material is preferably in a pure form or in a hydrogenated form. US patent application US 2013/0263699 A1 and German patent DE 198 43 883 CI describe a process called hydrogen decrepitation (HD) for producing a hydrogenated form of the magnetic starting material by means of hydrogen-induced decay.
Vorzugsweise wird das magnetische Ausgangsmaterial mechanisch, insbesondere durch Mahlen, auf eine Partikelgröße von 1 pm bis 200 pm zerkleinert, um das pulverförmige magnetische Ausgangsmaterial zu gewinnen. The magnetic starting material is preferably comminuted mechanically, in particular by grinding, to a particle size of 1 μm to 200 μm in order to obtain the magnetic starting material in powder form.
Gemäß einer Weiterbildung der Erfindung ist vorgesehen, dass als magnetisches Ausgangsmaterial ein Material verwendet wird, welches Partikel einer RxTyB -Legierung aufweist. Vorzugsweise wird als magnetisches Ausgangsmaterial ein Material verwendet, welches aus Partikeln einer RxTyB -Legierung besteht. Insbesondere wird bevorzugt als magnetisches Ausgangsmaterial ein Material verwendet, welches Partikel einer NdxFeyB-Legierung aufweist oder aus Partikeln einer NdxFeyB-Legierung besteht. Vorzugsweise wird als magnetisches Ausgangsmaterial ein Material verwendet, welches Partikel einer RxTyB -Legierung und Partikel einer Seltene-Erden-reichen Phase aufweist. Insbesondere besteht das magnetische Ausgangsmaterial bevorzugt aus einem Gemisch aus Partikeln einer RxTyB -Legierung und Partikeln einer Seltene-Erden-reichen Phase. Bevorzugt wird als magnetisches Ausgangsmaterial ein Material verwendet, welches Partikel einer NdxFeyB- Legierung und Partikel einer Neodym-reichen Phase aufweist oder aus solchen Partikeln besteht. Insbesondere weist das magnetische Ausgangsmaterial bevorzugt ein Gemisch aus Partikeln einer NdxFeyB-Legierung und Partikeln einer Neodym-reichen Phase auf oder besteht aus einem solchen Gemisch. According to a further development of the invention, it is provided that a material which has particles of an R x T y B alloy is used as the magnetic starting material. A material consisting of particles of an R x T y B alloy is preferably used as the magnetic starting material. In particular, a material which has particles of an Nd x Fe y B alloy or consists of particles of an Nd x Fe y B alloy is preferably used as the magnetic starting material. A material which has particles of an R x T y B alloy and particles of a phase rich in rare earths is preferably used as the magnetic starting material. In particular, the magnetic source material preferably consists of a mixture of R x TyB alloy particles and rare earth-rich phase particles. A material which has particles of an Nd x Fe y B alloy and particles of a neodymium-rich phase or consists of such particles is preferably used as the magnetic starting material. In particular, the magnetic starting material preferably has a mixture of particles of an Nd x Fe y B alloy and particles of a neodymium-rich phase or consists of such a mixture.
Im Kontext der vorliegenden technischen Lehre steht R für ein Seltene-Erden-Element, T für mindestens ein Element, ausgewählt aus einer Gruppe, bestehend aus Eisen und Cobalt, und B für das Element Bor. Insbesondere substituieren sich die Elemente Eisen und Cobalt teilweise oder vollständig derart, dass entweder nur Eisen oder nur Cobalt oder eine beliebige Eisen-Cobalt- Mischung vorliegt. Vorzugsweise ist das Seltene-Erden-Element Neodym. In einer bevorzugten Ausführungsform umfasst die RxTyB -Legierung zusätzlich ein weiteres Element, vorzugsweise ein Metall, insbesondere ein Übergangsmetall, ausgewählt aus einer Gruppe, bestehend aus Aluminium, Kupfer, Zirkonium, Gallium, Hafnium, und Niob, vorzugsweise in Spuren. In the context of the present technical teaching, R is a rare earth element, T is at least one element selected from a group consisting of iron and cobalt, and B is the element boron. In particular, the elements iron and cobalt partially or partially substitute each other completely such that either only iron or only cobalt or any iron-cobalt mixture is present. Preferably the rare earth element is neodymium. In a preferred embodiment, the R x T y B alloy additionally comprises a further element, preferably a metal, in particular a transition metal selected from a group consisting of aluminum, copper, zirconium, gallium, hafnium and niobium, preferably in traces.
Vorzugsweise weist das magnetische Ausgangsmaterial Partikel einer Nd2Fei4B -Legierung auf oder besteht aus Partikeln einer Nd2Fei4B -Legierung. The magnetic starting material preferably has particles of an Nd2Fei4B alloy or consists of particles of an Nd2Fei4B alloy.
Vorzugsweise weist die Seltene-Erden-reiche Phase, insbesondere die Neodym-reiche Phase, mindestens ein Seltene-Erden-Element, insbesondere Neodym, oder eine chemische Verbindung dieses Seltene-Erden-Elements, insbesondere von Neodym, auf. Zusätzlich enthält die Seltene- Erden-reiche Phase, insbesondere die Neodym-reiche Phase, bevorzugt mindestens ein weiteres Element der RxTyB -Legierung, insbesondere der NdxFeyB -Legierung. Alternativ oder zusätzlich liegt das mindestens eine Seltene-Erden-Element, insbesondere Neodym, in einer hydrierten Form vor. Vorzugsweise weist die Neodym-reiche Phase NdH2 und/oder NdH2,7 auf oder besteht aus NdH2 und/oder NdH2,7. Alternativ ist es in bevorzugter Ausgestaltung möglich, dass die Seltene- Erden-reiche Phase, insbesondere die Neodym-reiche Phase, aus mindestens einem Seltene-Erden- Element, insbesondere aus Neodym, oder aus einer chemischen Verbindung dieses Seltene-Erden- Elements, insbesondere von Neodym, besteht. Die Seltene-Erden-reiche Phase bildet bevorzugt im Gefüge des Permanentmagneten eine Phase, die sich an Korngrenzen des Gefüges befindet. The rare earth-rich phase, in particular the neodymium-rich phase, preferably has at least one rare earth element, in particular neodymium, or a chemical compound of this rare earth element, in particular neodymium. In addition, the rare earth-rich phase, in particular the neodymium-rich phase, preferably contains at least one further element of the R x T y B alloy, in particular the Nd x Fe y B alloy. Alternatively or additionally, the at least one rare earth element, in particular neodymium, is in a hydrogenated form. The neodymium-rich phase preferably has NdH2 and/or NdH2.7 or consists of NdH2 and/or NdH2.7. Alternatively, it is possible in a preferred embodiment that the rare earth-rich phase, in particular the neodymium-rich phase, consists of at least one rare earth element, in particular neodymium, or a chemical compound of this rare earth element, in particular of neodymium. The phase rich in rare earths preferably forms a phase in the structure of the permanent magnet that is located at grain boundaries of the structure.
Gemäß einer Weiterbildung der Erfindung ist vorgesehen, dass das magnetische Ausgangsmaterial mit einem organischen Binder vermischt wird, wobei ein Gemisch aus dem magnetischen Ausgangsmaterial und dem organischen Binder erhalten wird. Die Rohform wird aus dem Gemisch erstellt, wobei der organischen Binder vor der Kornfeinung zumindest teilweise aus der Rohform entfernt wird. Vorzugsweise wird der organische Binder vor der Kornfeinung komplett aus der Rohform entfernt. Vorteilhafterweise wird das magnetische Ausgangsmaterial, vorzugsweise in Pulverform, mit dem organischen Binder vermischt. Weiterhin ist die Formung der Rohform aus dem Gemisch in einfacher Weise möglich. According to a development of the invention, it is provided that the magnetic starting material is mixed with an organic binder, with a mixture of the magnetic starting material and the organic binder being obtained. The raw form is created from the mixture, with the organic binder being at least partially removed from the raw form before grain refinement. The organic binder is preferably completely removed from the raw form before grain refinement. The magnetic starting material, preferably in powder form, is advantageously mixed with the organic binder. Furthermore, the molding of the raw form from the mixture is possible in a simple manner.
In einer Ausführungsform des Verfahrens wird der organische Binder in einer Wasserstoff- Atmosphäre oder einer Wasserstoff-Inertgas-Atmosphäre bei einem Druck von mindestens 50 mbar absolut bis höchstens 100 mbar über Atmosphärendruck, vorzugsweise bei 50 mbar über Atmosphärendruck, zumindest teilweise, vorzugsweise komplett aus der Rohform entfernt. Dabei wird die Rohform mit einer Heizrate von mindestens 0,1 K/min bis höchstens 10 K/min auf eine Temperatur von mindestens 350 °C bis höchstens 650 °C erhitzt. Während der Erhitzung der Rohform wird vorzugsweise bei mindestens einer vorbestimmten Temperatur eine Haltestufe vorgesehen, insbesondere werden bei einer Mehrzahl vorbestimmter Temperaturen Haltestufen eingebaut, wobei die Temperatur bei der mindestens einen Haltestufe für eine vorbestimmte Dauer, vorzugsweise von mindestens 30 Minuten bis höchstens 300 Minuten, aufrechterhalten wird. Insbesondere wird bei einer bevorzugten Haltestufe eine Temperatur von 600 °C für eine Dauer von 180 Minuten aufrechterhalten. Somit dauert eine reine Erhitzung ohne Haltestufen, insbesondere in Abhängigkeit von der Heizrate und der Temperatur, auf welche die Rohform erhitzt wird, mindestens 35 Minuten bis höchstens 6500 Minuten. Eine Dauer des kompletten Prozesses zur Entfernung des organischen Binders aus der Rohform in bevorzugter Ausgestaltung ergibt sich aus der gewählten Heizrate, der Temperatur, auf welche die Rohform erhitzt wird, und einer Anzahl und einer jeweiligen Dauer der Haltestufen. In one embodiment of the method, the organic binder is in a hydrogen atmosphere or a hydrogen inert gas atmosphere at a pressure of at least 50 mbar absolute to at most 100 mbar above atmospheric pressure, preferably at 50 mbar above atmospheric pressure, at least partially, preferably completely from the Rough form removed. The raw mold is heated to a temperature of at least 350 °C and at most 650 °C at a heating rate of at least 0.1 K/min and at most 10 K/min. During the heating of the raw mold, a holding stage is preferably provided at at least one predetermined temperature; in particular, holding stages are installed at a plurality of predetermined temperatures, with the temperature being maintained at the at least one holding stage for a predetermined period of time, preferably from at least 30 minutes to a maximum of 300 minutes will. In particular, a preferred soak stage maintains a temperature of 600°C for a period of 180 minutes. Thus, pure heating without holding stages lasts at least 35 minutes to at most 6500 minutes, in particular depending on the heating rate and the temperature to which the raw mold is heated. The duration of the complete process for removing the organic binder from the raw mold in a preferred embodiment results from the selected heating rate, the temperature to which the raw mold is heated, and a number and a respective duration of the holding stages.
In einer weiteren Ausführungsform des Verfahrens wird der organische Binder in einer Inertgas- Atmosphäre bei einem Druck von mindestens 10’5 mbar absolut bis höchstens 100 mbar über Atmosphärendruck, vorzugsweise bei 50 mbar über Atmosphärendruck, zumindest teilweise, vorzugsweise komplett aus der Rohform entfernt. Dabei wird die Rohform mit einer Heizrate von mindestens 0,1 K/min bis höchstens 10 K/min auf eine Temperatur von mindestens 350 °C bis höchstens 650 °C erhitzt. Während der Erhitzung der Rohform wird vorzugsweise bei mindestens einer vorbestimmten Temperatur eine Haltestufe vorgesehen, insbesondere werden bei einer Mehrzahl vorbestimmter Temperaturen Haltestufen eingebaut, wobei die Temperatur bei der mindestens einen Haltestufe für eine vorbestimmte Dauer aufrechterhalten wird. Insbesondere wird bei einer bevorzugten Haltestufe eine Temperatur von 600 °C für eine Dauer von 180 Minuten aufrechterhalten. Der komplette Prozess zur Entfernung des organischen Binders aus der Rohform dauert in bevorzugter Ausgestaltung mindestens 30 Minuten bis höchstens 300 Minuten. In a further embodiment of the method, the organic binder is at least partially, preferably completely removed from the raw form in an inert gas atmosphere at a pressure of at least 10′5 mbar absolute to at most 100 mbar above atmospheric pressure, preferably at 50 mbar above atmospheric pressure. The raw mold is heated to a temperature of at least 350° C. at a heating rate of at least 0.1 K/min and at most 10 K/min heated to a maximum of 650 °C. During the heating of the raw mold, a holding stage is preferably provided at at least one predetermined temperature, in particular holding stages are installed at a plurality of predetermined temperatures, the temperature at the at least one holding stage being maintained for a predetermined period. In particular, a preferred soak stage maintains a temperature of 600°C for a period of 180 minutes. In a preferred embodiment, the complete process for removing the organic binder from the raw form lasts at least 30 minutes and at most 300 minutes.
Zusätzlich kann, nach der zumindest teilweisen, vorzugweise kompletten, Entfernung des organischen Binders aus der Rohform, die Rohform in einer Wasserstoff aufweisenden Atmosphäre, insbesondere in einer Wasserstoffatmosphäre, insbesondere in reinem Wasserstoff, vorzugsweise bei einem Druck von mindestens 50 mbar absolut bis höchstens 50 mbar über Atmosphärendruck, bei einer Temperatur von mindestens 600 °C bis höchstens 900 °C, vorzugsweise für eine Dauer von mindestens 30 Minuten bis höchstens 180 Minuten, hydriert werden. In addition, after the at least partial, preferably complete, removal of the organic binder from the raw form, the raw form can be exposed to an atmosphere containing hydrogen, in particular in a hydrogen atmosphere, in particular in pure hydrogen, preferably at a pressure of at least 50 mbar absolute to at most 50 mbar above atmospheric pressure, at a temperature of at least 600°C and at most 900°C, preferably for a period of at least 30 minutes and at most 180 minutes.
Unter einer Wasserstoffatmosphäre wird im Kontext der vorliegenden technischen Lehre insbesondere ein Gas verstanden, das aus reinem Wasserstoff und Verunreinigungen von höchstens 5 Vol.-% besteht. In the context of the present technical teaching, a hydrogen atmosphere is understood to mean, in particular, a gas which consists of pure hydrogen and impurities of at most 5% by volume.
Gemäß einer Weiterbildung der Erfindung ist vorgesehen, dass das magnetische Ausgangsmaterial mit einem organischen Lösungsmittel vermischt wird, wobei ein Gemisch aus dem magnetischen Ausgangsmaterial und dem organischen Lösungsmittel erhalten wird. Die Rohform wird aus dem Gemisch erstellt, wobei das organische Lösungsmittel vor der Kornfeinung zumindest teilweise aus der Rohform entfernt wird. Vorzugsweise wird das organische Lösungsmittel vor der Kornfeinung komplett aus der Rohform entfernt. Vorteilhafterweise wird das magnetische Ausgangsmaterial, vorzugsweise in Pulverform, mit dem organische Lösungsmittel vermischt. Weiterhin ist die Formung der Rohform aus dem Gemisch in einfacher Weise möglich. According to a development of the invention, it is provided that the magnetic starting material is mixed with an organic solvent, a mixture of the magnetic starting material and the organic solvent being obtained. The raw form is created from the mixture, with the organic solvent being at least partially removed from the raw form before grain refinement. The organic solvent is preferably completely removed from the raw form before grain refinement. Advantageously, the magnetic starting material, preferably in powder form, is mixed with the organic solvent. Furthermore, the molding of the raw form from the mixture is possible in a simple manner.
In einer Ausführungsform des Verfahrens wird das organische Lösungsmittel bei einer Temperatur von höchstens 250 °C und/oder unter Vakuum, insbesondere bei einem Druck von mindestens 10’ 5 mbar absolut bis höchstens 800 mbar absolut, für eine Dauer von mindestens 30 Minuten bis höchstens 180 Minuten abgedampft. Gemäß einer Weiterbildung der Erfindung ist vorgesehen, dass die Kornfeinung einen Wasserstoff-Einlagerungsschritt und einen - dem Wasserstoff-Einlagerungsschritt nachfolgenden - Rekombinationsschritt aufweist. Bei dem Wasserstoff-Einlagerungsschritt wird die Rohform, insbesondere die Partikel des magnetischen Ausgangsmaterials, aus welchem die Rohform besteht, mit Wasserstoff zur Reaktion gebracht. Bei dem Rekombinationsschritt wird der Rohform der Wasserstoff zumindest teilweise, vorzugweise komplett, entzogen. In one embodiment of the method, the organic solvent is heated at a maximum temperature of 250° C. and/or under vacuum, in particular at a pressure of at least 10'5 mbar absolute to a maximum of 800 mbar absolute, for a period of at least 30 minutes to a maximum of 180 minutes evaporated. According to a development of the invention, it is provided that the grain refinement has a hydrogen storage step and a recombination step—following the hydrogen storage step. In the hydrogen occlusion step, the raw form, particularly the particles of the magnetic source material constituting the raw form, is reacted with hydrogen. In the recombination step, the hydrogen is at least partially, preferably completely, withdrawn from the raw form.
Vorteilhafterweise findet während des Wasserstoff-Einlagerungsschritts an den Neodym-Eisen- Bor-Partikeln die chemische Reaktion The chemical reaction advantageously takes place on the neodymium-iron-boron particles during the hydrogen storage step
Nd2Fei4B + x H2 — ► 2 NdHx + 12 Fe + Fe2B (1) statt, wobei x eine positive Zahl ist. Vorteilhafterweise reagieren die in der Neodym-reichen Phase vorliegenden Neodym-Eisen-Bor-Körner mit dem Wasserstoff und führen zur Ausbildung einer Neodym-Wasserstoff-Phase, einer Eisen-Phase und einer Eisen-Bor-Phase. Die Neodym- Wasserstoff-Phasen, die Eisen-Phasen und die Eisen-Bor-Phasen liegen insbesondere zusätzlich zu den Neodym- Eisen-Bor-Phasen vor, das heißt die Reaktion gemäß der Gleichung (1) verläuft nicht quantitativ. Vorteilhafterweise entstehen die Neodym-Wasserstoff-Phasen, die Eisen-Phasen und die Eisen-B or- Phasen als kleine, fein verteilte Inseln in dem initialen Neodym-Eisen-Bor- Kom. Somit zerfällt das Korn nicht und bleibt insbesondere formstabil. Darüber hinaus bleibt damit auch die Rohform formstabil. Nd 2 Fe i4 B + x H 2 — ► 2 NdH x + 12 Fe + Fe 2 B (1) where x is a positive number. Advantageously, the neodymium-iron-boron grains present in the neodymium-rich phase react with the hydrogen and result in the formation of a neodymium-hydrogen phase, an iron phase and an iron-boron phase. The neodymium-hydrogen phases, the iron phases and the iron-boron phases are present in particular in addition to the neodymium-iron-boron phases, ie the reaction according to equation (1) does not proceed quantitatively. Advantageously, the neodymium-hydrogen phases, the iron phases and the iron-boron phases form as small, finely divided islands in the initial neodymium-iron-boron grain. The grain therefore does not disintegrate and, in particular, remains dimensionally stable. In addition, the raw form remains dimensionally stable.
Vorteilhafterweise findet während des Rekombinations Schrittes eine Rückreaktion der chemischen Reaktion (1) statt. Dabei wird der Wasserstoff gemäß der chemischen Reaktion A reverse reaction of the chemical reaction (1) advantageously takes place during the recombination step. Here, the hydrogen according to the chemical reaction
2 NdHx + 12 Fe + Fe2B Nd2Fei4B + x H2 (2) zumindest teilweise, vorzugsweise komplett, entzogen, das heißt die Reaktion gemäß der Gleichung (2) verläuft bevorzugt quantitativ. Vorteilhafterweise werden bei der chemischen Reaktion (2) die kleinen, fein verteilten Inseln der Neodym-Wasserstoff-Phasen, der Eisen-Phasen und der Eisen-Bor-Phasen, welche bei der chemischen Reaktion (1) entstehen, zu kleinen Körnern der Neodym-Eisen-Bor-Phase zusammengefügt. 2 NdH x + 12 Fe + Fe 2 B Nd 2 Fe 14 B + x H 2 (2) at least partially, preferably completely, removed, ie the reaction according to equation (2) preferably proceeds quantitatively. Advantageously, in chemical reaction (2), the small, finely divided islands of neodymium-hydrogen phases, iron phases, and iron-boron phases formed in chemical reaction (1) become small grains of neodymium Iron-boron phase merged.
Vorteilhafterweise unterscheidet sich die Neodym-Eisen-Bor-Phase, welche das Edukt der chemischen Reaktion (1) bildet, von der Neodym-Eisen-Bor-Phase, welche das Produkt der chemischen Reaktion (2) bildet, in der Korngröße der jeweiligen Phase. Dabei sind die Neodym- Eisen-Bor-Körner nach dem Rekombinations schritt, insbesondere nach der chemischen Reaktion (2), kleiner sind als die Neodym-Eisen-Bor-Körner vor dem Wasserstoff-Einlagerungsschritt, insbesondere vor der chemischen Reaktion (1). Darüber hinaus bleibt die magnetische Achse der Neodym-Eisen-Bor-Körner nahezu identisch, vorzugsweise komplett identisch. Advantageously, the neodymium-iron-boron phase, which forms the educt of the chemical reaction (1), differs from the neodymium-iron-boron phase, which forms the product of the chemical reaction (2), in the grain size of the respective phase . The neodymium Iron-boron grains after the recombination step, especially after the chemical reaction (2), are smaller than the neodymium-iron-boron grains before the hydrogen occlusion step, especially before the chemical reaction (1). In addition, the magnetic axis of the neodymium-iron-boron grains remains almost identical, preferably completely identical.
Gemäß einer Weiterbildung der Erfindung ist vorgesehen, dass der Wasserstoff- Einlagerungsschritt in einer Wasserstoff aufweisenden Atmosphäre unter einem vorbestimmten Einlagerung s -Druck für eine vorbestimmte Einlagerungs-Dauer durchgeführt wird. Weiterhin wird die Rohform während des Wasserstoff-Einlagerungsschrittes auf eine vorbestimmte Einlagerung s -Temperatur erhitzt. According to a development of the invention, it is provided that the hydrogen storage step is carried out in an atmosphere containing hydrogen under a predetermined storage s pressure for a predetermined storage period. Furthermore, during the hydrogen incorporation step, the green form is heated to a predetermined incorporation s temperature.
Vorzugsweise ist der vorbestimmte Einlagerungs-Druck mindestens 50 mbar absolut bis höchstens 50 mbar über Atmosphärendruck. Weiterhin ist die vorbestimmte Einlagerungs-Dauer vorzugsweise mindestens 30 Minuten bis höchstens 300 Minuten. Die vorbestimmte Einlagerung s -Temperatur ist vorzugsweise mindestens 750 °C bis höchstens 900 °C und wird insbesondere mittels einer Heizrate von mindestens 0,1 K/min bis höchstens 10 K/min, bevorzugt 3 K/min, erreicht. Preferably, the predetermined storage pressure is at least 50 mbar absolute to at most 50 mbar above atmospheric pressure. Furthermore, the predetermined storage period is preferably at least 30 minutes to at most 300 minutes. The predetermined storage s temperature is preferably at least 750° C. to at most 900° C. and is achieved in particular by means of a heating rate of at least 0.1 K/min to at most 10 K/min, preferably 3 K/min.
In einer Ausführungsform des Verfahrens wird der Wasserstoff-Einlagerungsschritt in einer Atmosphäre, welche aus Wasserstoff besteht, insbesondere in einer Wasserstoffatmosphäre oder in reinem Wasserstoff, durchgeführt. In one embodiment of the method, the hydrogen storage step is carried out in an atmosphere consisting of hydrogen, in particular in a hydrogen atmosphere or in pure hydrogen.
In einer weiteren Ausführungsform des Verfahrens wird der Wasserstoff-Einlagerungsschritt in einer Atmosphäre, welche Wasserstoff und mindestens ein Inertgas, insbesondere ausgewählt aus Argon und Helium, aufweist, vorzugsweise aus Wasserstoff und mindestens einem Inertgas, insbesondere ausgewählt aus Argon und Helium, besteht, durchgeführt. In a further embodiment of the method, the hydrogen storage step is carried out in an atmosphere which has hydrogen and at least one inert gas, in particular selected from argon and helium, preferably consists of hydrogen and at least one inert gas, in particular selected from argon and helium.
Bevorzugt weist die Atmosphäre, in welcher der Wasserstoff-Einlagerungsschritt durchgeführt wird, mindestens 60 Vol.-% Wasserstoff und mindestens ein Inertgas, insbesondere ausgewählt aus Argon und Helium, auf, oder sie besteht aus mindestens 60 Vol.-% Wasserstoff und mindestens einem Inertgas, insbesondere ausgewählt aus Argon und Helium. Besonders bevorzugt wird der Wasserstoff-Einlagerungsschritt in einer Wasserstoffatmosphäre, insbesondere in reinem Wasserstoff durchgeführt. Gemäß einer Weiterbildung der Erfindung ist vorgesehen, dass der Rekombinationsschritt in einer ein Verfahrensgas aufweisenden oder aus dem Verfahrensgas bestehenden Atmosphäre unter einem vorbestimmten Rekombinations-Druck und einer vorbestimmten Rekombinations- Temperatur für eine vorbestimmte Rekombinations-Dauer durchgeführt wird. The atmosphere in which the hydrogen storage step is carried out preferably has at least 60% by volume hydrogen and at least one inert gas, in particular selected from argon and helium, or it consists of at least 60% by volume hydrogen and at least one inert gas , in particular selected from argon and helium. The hydrogen storage step is particularly preferably carried out in a hydrogen atmosphere, in particular in pure hydrogen. According to a development of the invention, it is provided that the recombination step is carried out in an atmosphere containing a process gas or consisting of the process gas under a predetermined recombination pressure and a predetermined recombination temperature for a predetermined recombination duration.
Vorzugsweise ist die vorbestimmte Rekombinations-Temperatur mindestens 750 °C bis höchstens 900 °C. Alternativ oder zusätzlich ist die vorbestimmte Rekombinations-Dauer vorzugsweise mindestens 30 Minuten bis höchstens 300 Minuten. Preferably, the predetermined recombination temperature is at least 750°C to at most 900°C. Alternatively or additionally, the predetermined recombination duration is preferably at least 30 minutes to at most 300 minutes.
In einer Ausführungsform des Verfahrens ist der vorbestimmte Rekombinations-Druck mindestens 10’5 mbar absolut bis höchstens 10’3 mbar absolut. Weiterhin beträgt die vorbestimmte Rekombinations-Temperatur mindestens 750 °C bis höchstens 900 °C. Der Rekombinationsschritt wird für die vorbestimmte Rekombinations-Dauer von mindestens 30 Minuten bis höchstens 300 Minuten durchgeführt. In one embodiment of the method, the predetermined recombination pressure is at least 10′ 5 mbar absolute and at most 10′ 3 mbar absolute. Furthermore, the predetermined recombination temperature is at least 750°C and at most 900°C. The recombination step is carried out for the predetermined recombination duration of at least 30 minutes and at most 300 minutes.
Gemäß einer Weiterbildung der Erfindung ist vorgesehen, dass das Verfahrensgas ausgewählt ist aus einer Gruppe, bestehend aus Wasserstoff, Argon, und Helium. According to a development of the invention, it is provided that the process gas is selected from a group consisting of hydrogen, argon and helium.
In einer weiteren Ausführungsform des Verfahrens beträgt der vorbestimmte Rekombinations- Druck mindestens 10’3 mbar absolut bis höchstens 900 mbar absolut, besonders bevorzugt bis höchstens 200 mbar absolut, wobei die Atmosphäre das Verfahrensgas Wasserstoff aufweist. Insbesondere weist die Atmosphäre, in welcher der Rekombinations schritt durchgeführt wird, höchstens 40 Vol.-%, vorzugsweise höchstens 20 Vol.-%, Wasserstoff und mindestens ein Inertgas, insbesondere ausgewählt aus Argon und Helium, auf, oder die Atmosphäre besteht aus höchstens 40 Vol.-%, vorzugsweise höchstens 20 Vol.-%, Wasserstoff und mindestens einem Inertgas, insbesondere ausgewählt aus Argon und Helium. Alternativ oder zusätzlich weist die Atmosphäre, in welcher der Rekombinationsschritt durchgeführt wird, insbesondere mindestens 60 Vol.-%, vorzugsweise mindestens 80 Vol.-%, Inertgas auf, wobei hierfür die Volumenanteile aller Inertgase, welche die Atmosphäre aufweist, addiert werden. Alternativ wird der Rekombinationsschritt in einer Wasserstoffatmosphäre oder in reinem Wasserstoff durchgeführt. Weiterhin beträgt die vorbestimmte Rekombinations-Temperatur mindestens 750 °C bis höchstens 900 °C. Der Rekombinationsschritt wird für die vorbestimmte Rekombinations-Dauer von mindestens 30 Minuten bis höchstens 300 Minuten durchgeführt. In einer weiteren Ausführungsform des Verfahrens beträgt der vorbestimmte Rekombinations- Druck mindestens 10’3 mbar absolut bis höchstens 50 mbar über Atmosphärendruck, wobei die Atmosphäre aus dem Verfahrensgas Argon und/oder Helium besteht. Weiterhin beträgt die vorbestimmte Rekombinations-Temperatur mindestens 750 °C bis höchstens 900 °C. Der Rekombinationsschritt wird für die vorbestimmte Rekombinations-Dauer von mindestens 30 Minuten bis höchstens 300 Minuten durchgeführt. In a further embodiment of the method, the predetermined recombination pressure is at least 10'3 mbar absolute up to at most 900 mbar absolute, particularly preferably up to at most 200 mbar absolute, the atmosphere containing the process gas hydrogen. In particular, the atmosphere in which the recombination step is carried out has at most 40% by volume, preferably at most 20% by volume, hydrogen and at least one inert gas, in particular selected from argon and helium, or the atmosphere consists of at most 40 % by volume, preferably at most 20% by volume, hydrogen and at least one inert gas, in particular selected from argon and helium. Alternatively or additionally, the atmosphere in which the recombination step is carried out has in particular at least 60% by volume, preferably at least 80% by volume, inert gas, with the volume fractions of all inert gases in the atmosphere being added up for this purpose. Alternatively, the recombination step is carried out in a hydrogen atmosphere or in pure hydrogen. Furthermore, the predetermined recombination temperature is at least 750°C and at most 900°C. The recombination step is carried out for the predetermined recombination duration of at least 30 minutes and at most 300 minutes. In a further embodiment of the method, the predetermined recombination pressure is at least 10'3 mbar absolute to at most 50 mbar above atmospheric pressure, the atmosphere consisting of the process gas argon and/or helium. Furthermore, the predetermined recombination temperature is at least 750°C and at most 900°C. The recombination step is carried out for the predetermined recombination duration of at least 30 minutes and at most 300 minutes.
Gemäß einer Weiterbildung der Erfindung ist vorgesehen, dass die Rohform während oder nach dem Rekombinations schritt auf eine vorbestimmte Abkühlung-Temperatur abgekühlt wird. According to a development of the invention, it is provided that the raw mold is cooled to a predetermined cooling temperature during or after the recombination step.
Gemäß einer Weiterbildung der Erfindung ist vorgesehen, dass die Rohform mittels eines Verfahrens, ausgewählt aus einer Gruppe, bestehend aus Spritzgießen, insbesondere Metallpulver- Spritzgießen, additivem Fertigen, Extrudieren, Kaltpressen, und Heißpressen, hergestellt wird. According to a development of the invention, it is provided that the raw form is produced by means of a method selected from a group consisting of injection molding, in particular metal powder injection molding, additive manufacturing, extrusion, cold pressing and hot pressing.
In einer Ausführungsform des Verfahrens wird die Rohform mittels Spritzgießen eines Gemisches, welches das magnetische Ausgangsmaterial und den organischen Binder aufweist, hergestellt. In one embodiment of the method, the raw form is produced by injection molding a mixture comprising the magnetic starting material and the organic binder.
In einer weiteren Ausführungsform des Verfahrens wird die Rohform mittels Kaltpressen eines magnetischen Ausgangsmaterials hergestellt. Beim Kaltpressen werden die Partikel, insbesondere unter einem Druck von bis zu 1 GPa, mechanisch verzahnt. Beim Trocken-Kaltpressen wird dem magnetischen Ausgangsmaterial insbesondere keine zusätzliche flüssige Komponente beigefügt. Beim Nass-Kaltpressen wird dem magnetischen Ausgangsmaterial ein organisches Lösungsmittel, vorzugsweise ein flüchtiges unpolares und/oder polares organisches Lösungsmittel, beigefügt. Das flüchtige unpolare und/oder polare organische Lösungsmittel ist ausgewählt aus einer Gruppe, bestehend aus einem Alkohol, einem acyclischen Alkan, einem cyclischen Alkan, einem Keton, und einem Gemisch aus flüchtigen organischen Substanzen, die als Lösungsmittel dienen können. Als Alkohol wird vorzugsweise Ethanol oder Isopropanol verwendet. Als cyclisches Alkan wird vorzugsweise Cyclohexan verwendet. Als Keton wird vorzugsweise Aceton verwendet. Das Gemisch aus flüchtigen organischen Substanzen ist vorzugsweise ausgewählt aus einer Gruppe, bestehend aus Petroleum, Testbenzin, und Leichtbenzin. Das organische Lösungsmittel dient beim Nass-Kaltpressen insbesondere als Binder. Weiterhin wird die Rohform vorzugsweise vor dem Sintern getrocknet. In einer weiteren Ausführungsform des Verfahrens wird die Rohform mittels Heißpressen eines magnetischen Ausgangsmaterials hergestellt. Beim Heißpressen werden die Partikel insbesondere mechanisch verzahnt und/oder kaltverschweißt. In a further embodiment of the method, the raw form is produced by cold pressing a magnetic starting material. During cold pressing, the particles are mechanically interlocked, in particular under a pressure of up to 1 GPa. In dry cold pressing, in particular, no additional liquid component is added to the magnetic starting material. In wet cold pressing, an organic solvent, preferably a volatile non-polar and/or polar organic solvent, is added to the magnetic starting material. The volatile non-polar and/or polar organic solvent is selected from a group consisting of an alcohol, an acyclic alkane, a cyclic alkane, a ketone, and a mixture of volatile organic substances that can serve as a solvent. Ethanol or isopropanol is preferably used as the alcohol. Cyclohexane is preferably used as the cyclic alkane. Acetone is preferably used as the ketone. The mixture of volatile organic substances is preferably selected from a group consisting of petroleum, mineral spirits, and mineral spirits. The organic solvent serves in particular as a binder in wet cold pressing. Furthermore, the raw form is preferably dried before sintering. In a further embodiment of the method, the raw form is produced by hot pressing a magnetic starting material. During hot pressing, the particles are in particular mechanically interlocked and/or cold-welded.
Gemäß einer Weiterbildung der Erfindung ist vorgesehen, dass die Rohform in einem extern anliegenden Magnetfeld hergestellt wird. Vorteilhafterweise werden Dipole des magnetischen Ausgangsmaterials mittels des extern anliegenden Magnetfelds bei der Herstellung der Rohform in einer parallelen Orientierung ausgerichtet. According to a development of the invention, it is provided that the raw mold is produced in an externally applied magnetic field. Dipoles of the magnetic starting material are advantageously aligned in a parallel orientation by means of the externally applied magnetic field during the production of the raw form.
Vorzugsweise wird das extern anliegende Magnetfeld von einem schaltbaren Elektromagneten und/oder einem Permanentmagneten erzeugt. The externally applied magnetic field is preferably generated by a switchable electromagnet and/or a permanent magnet.
Gemäß einer Weiterbildung der Erfindung ist vorgesehen, dass die Rohform bei einem vorbestimmten Sinter-Druck und bei einer vorbestimmten Sinter-Temperatur, vorzugsweise einer Temperatur von mindestens 900 °C bis höchstens 1200 °C, in einer aus einem Prozessgas bestehenden Atmosphäre für eine vorbestimmte Sinter-Dauer gesintert wird. According to a development of the invention, it is provided that the raw form is sintered at a predetermined sintering pressure and at a predetermined sintering temperature, preferably a temperature of at least 900° C. to at most 1200° C., in an atmosphere consisting of a process gas for a predetermined sintering - Duration is sintered.
Vorzugsweise beträgt die vorbestimmte Sinter-Dauer mindestens 30 Minuten bis höchstens 240 Minuten. Alternativ oder zusätzlich beträgt der vorbestimmte Sinter-Druck mindestens 10’5 mbar absolut bis höchstens 50 mbar über Atmosphärendruck. The predetermined sintering time is preferably at least 30 minutes and at most 240 minutes. Alternatively or additionally, the predetermined sintering pressure is at least 10'5 mbar absolute to at most 50 mbar above atmospheric pressure.
Gemäß einer Weiterbildung der Erfindung ist vorgesehen, dass das Prozessgas ausgewählt ist aus einer Gruppe, bestehend aus Argon und Helium. According to a development of the invention, it is provided that the process gas is selected from a group consisting of argon and helium.
In einer Ausführungsform des Verfahrens wird die Rohform in einer Atmosphäre, welche aus Argon und/oder Helium besteht, bei einem vorbestimmten Sinter-Druck von mindestens 10’5 mbar absolut bis höchstens 50 mbar über Atmosphärendruck und bei einer vorbestimmten Sinter- Temperatur von mindestens 1000 °C bis höchstens 1200 °C für eine vorbestimmte Sinter-Dauer von mindestens 30 Minuten bis höchstens 240 Minuten gesintert. In one embodiment of the method, the raw mold is made in an atmosphere consisting of argon and/or helium at a predetermined sintering pressure of at least 10'5 mbar absolute to at most 50 mbar above atmospheric pressure and at a predetermined sintering temperature of at least 1000 °C up to a maximum of 1200 °C for a predetermined sintering time of at least 30 minutes and at most 240 minutes.
In einer weiteren Ausführungsform des Verfahrens wird die Rohform in einer Atmosphäre, welche aus Argon und/oder Helium besteht, bei einem vorbestimmten Sinter-Druck von mindestens 10’5 mbar absolut bis höchstens 50 mbar über Atmosphärendruck und bei einer vorbestimmten Sinter- Temperatur von mindestens 900 °C bis höchstens 1000 °C für eine vorbestimmte Sinter-Dauer von mindestens 30 Minuten bis höchstens 240 Minuten gesintert. Gemäß einer Weiterbildung der Erfindung ist vorgesehen, dass die gesinterte Rohform mittels Heißisostatischen Pressens nachbehandelt wird. Damit wird vorteilhafterweise die gesinterte Rohform nachverdichtet und ein übermäßiges Kornwachstum in dem sehr feinkörnige Gefüge verhindert. In a further embodiment of the method, the raw mold is made in an atmosphere consisting of argon and/or helium at a predetermined sintering pressure of at least 10'5 mbar absolute to at most 50 mbar above atmospheric pressure and at a predetermined sintering temperature of at least 900°C to a maximum of 1000°C for a predetermined sintering time of a minimum of 30 minutes to a maximum of 240 minutes. According to a development of the invention, it is provided that the sintered raw form is post-treated by means of hot isostatic pressing. This advantageously recompacts the sintered raw form and prevents excessive grain growth in the very fine-grain structure.
In einer bevorzugten Ausführungsform des Verfahrens wird das Heißisostatische Pressen bei einem Druck von mindestens 800 bar bis höchstens 2000 bar und einer Temperatur von mindestens 900 °C bis höchstens 1200 °C für eine Dauer von mindestens 30 Minuten bis höchstens 240 Minuten durchgeführt. In a preferred embodiment of the method, the hot isostatic pressing is carried out at a pressure of at least 800 bar to a maximum of 2000 bar and a temperature of at least 900° C. to a maximum of 1200° C. for a period of at least 30 minutes to a maximum of 240 minutes.
Gemäß einer Weiterbildung der Erfindung ist vorgesehen, dass die gesinterte Rohform einer zusätzlichen Wärmebehandlung unterzogen wird. Verfahren zur Wärmebehandlung sind aus dem Stand der Technik bekannt und ermöglichen eine zusätzliche Erhöhung der Koerzitivfeldstärke des Permanentmagneten, welcher mittels Sintern der Rohform entsteht. According to a development of the invention, it is provided that the sintered raw form is subjected to an additional heat treatment. Processes for heat treatment are known from the prior art and enable an additional increase in the coercive field strength of the permanent magnet, which is produced by sintering the raw form.
Zu Erfindung gehört auch ein Permanentmagnet, der mittels eines erfindungsgemäßen Verfahrens oder mittels eines Verfahrens nach einer oder mehreren der zuvor beschriebenen Ausführungsformen hergestellt ist. The invention also includes a permanent magnet which is produced by means of a method according to the invention or by means of a method according to one or more of the embodiments described above.
Zu Erfindung gehört weiterhin eine Verwendung eines solchen Permanentmagneten in einer Vorrichtung, ausgewählt aus einer Gruppe, bestehend aus einem Elektromotor, einem Lautsprecher, einem Mikrofon, einem Generator, einem Festplattenlaufwerk, und einem Sensor. The invention also includes use of such a permanent magnet in a device selected from a group consisting of an electric motor, a loudspeaker, a microphone, a generator, a hard disk drive and a sensor.
Zur Erfindung gehört auch eine Vorrichtung, ausgewählt aus einer Gruppe, bestehend aus einem Elektromotor, einem Lautsprecher, einem Mikrofon, einem Generator, einem Festplattenlaufwerk, und einem Sensor, wobei die Vorrichtung einen Permanentmagnet aufweist, welcher mittels eines erfindungsgemäßen Verfahrens oder eines Verfahrens nach einem oder mehreren der zuvor beschriebenen Ausführungsformen geschaffen wird. The invention also includes a device selected from a group consisting of an electric motor, a loudspeaker, a microphone, a generator, a hard disk drive, and a sensor, the device having a permanent magnet which is activated by a method according to the invention or a method according to a or more of the embodiments described above is provided.
Die Erfindung wird im Folgenden anhand der Zeichnung näher erläutert. Dabei zeigen: The invention is explained in more detail below with reference to the drawing. show:
Fig. 1 ein Flussdiagramm eines Verfahrens zur Herstellung eines Permanentmagneten, 1 shows a flow chart of a method for producing a permanent magnet,
Fig. 2 eine schematische Darstellung einer Ausführungsform einer Kornfeinung bei einem ersten Ausführungsbeispiel einer Rohform, und Fig. 3 eine schematische Darstellung eines zweiten Ausführungsbeispiels einer Rohform. 2 shows a schematic representation of an embodiment of grain refinement in a first exemplary embodiment of a raw mold, and 3 shows a schematic representation of a second exemplary embodiment of a raw mold.
Fig. 1 zeigt ein Flussdiagramm eines Verfahrens zur Herstellung eines Permanentmagneten. 1 shows a flow chart of a method for manufacturing a permanent magnet.
In Schritt a) wird das magnetische Ausgangsmaterial, vorzugsweise in Pulverform, zur Verfügung gestellt. Vorzugsweise entsteht das pulverförmige magnetische Ausgangsmaterial mittels Mahlen eines Gussblocks, eines schmelzgesponnenen Materials oder eines recycelten magnetischen Materials. Vorzugsweise wird das Ausgangsmaterial vor dem Mahlen mittels Wasserstoffversprödung versprödet. Vorzugsweise weist das magnetische Ausgangsmaterial Partikel einer RxTyB-Legierung, vorzugsweise einer Nd2Fei4B-Legierung, und vorzugsweise Partikel einer Seltene-Erden-reichen Phase auf. In step a), the magnetic starting material, preferably in powder form, is made available. Preferably, the powdery magnetic raw material is obtained by grinding an ingot, a melt-spun material, or a recycled magnetic material. Preferably, the starting material is embrittled by hydrogen embrittlement prior to milling. Preferably, the magnetic source material comprises particles of an R x T y B alloy, preferably a Nd2Fei4B alloy, and preferably particles of a rare earth-rich phase.
In Schritt b) wird das magnetische Ausgangsmaterial in Form gebracht, wobei eine in Figur 2 a) dargestellte Rohform 1 erstellt wird. Die Rohform 1 wird vorzugsweise mittels eines Verfahrens, ausgewählt aus einer Gruppe, bestehend aus Spritzgießen, additivem Fertigen, Extrudieren, Kaltpressen, und Heißpressen, hergestellt. Optional wird die Herstellung der Rohform 1 unter einem extern anliegenden Magnetfeld durchgeführt. Vorzugsweise wird das Magnetfeld von einem schaltbaren Elektromagneten und/oder einem Permanentmagneten erzeugt. In step b), the magnetic starting material is shaped, with a raw form 1 shown in FIG. 2a) being created. The raw mold 1 is preferably produced by a method selected from a group consisting of injection molding, additive manufacturing, extrusion, cold pressing, and hot pressing. Optionally, the production of the raw mold 1 is carried out under an externally applied magnetic field. The magnetic field is preferably generated by a switchable electromagnet and/or a permanent magnet.
In Schritt c) wird an der Rohform 1 eine Kornfeinung durchgeführt. Der Verfahrens schritt der Kornfeinung weist vorzugsweise einen Wasserstoff-Einlagerungsschritt, insbesondere Schritt cl), und ein Rekombinationsschritt, insbesondere Schritt c2), auf. Vorzugsweise wird in dem Wasserstoff-Einlagerungsschritt die Rohform 1, insbesondere die Partikel des magnetischen Ausgangsmaterials, aus welchem die Rohform 1 besteht, mit Wasserstoff zur Reaktion gebracht. Vorzugsweise wird der Wasserstoff-Einladungsschritt in einer Atmosphäre, welche Wasserstoff aufweist, unter einem vorbestimmten Einlagerung s -Druck für eine vorbestimmte Einlagerungs- Dauer durchgeführt. Während des Wasserstoff-Einlagerungsschrittes wird die Rohform 1 auf eine vorbestimmte Einlagerung s -Temperatur erhitzt. In step c), grain refinement is carried out on the raw mold 1 . The process step of grain refinement preferably has a hydrogen storage step, in particular step c1), and a recombination step, in particular step c2). Preferably, in the hydrogen storage step, the raw mold 1, particularly the particles of the magnetic raw material constituting the raw mold 1, are reacted with hydrogen. Preferably, the hydrogen charging step is performed in an atmosphere containing hydrogen under a predetermined storage pressure for a predetermined storage period. During the hydrogen storage step, the green mold 1 is heated to a predetermined storage s temperature.
Vorzugsweise wird in dem anschließenden Rekombinationsschritt der Wasserstoff zumindest teilweise, vorzugsweise komplett, der Rohform 1 entzogen. Vorzugsweise wird der Rekombinationsschritt in einer Atmosphäre, welche ein Verfahrensgas, vorzugsweise Wasserstoff, Argon, und/oder Helium, aufweist oder aus dem Verfahrensgas besteht, unter einem vorbestimmten Rekombinations-Druck und einer vorbestimmten Rekombinations-Temperatur für eine vorbestimmte Rekombinations-Dauer durchgeführt. Optional wird die Rohform 1 während oder nach dem Rekombinationsschritt, insbesondere während oder nach Schritt c2), auf eine vorbestimmte Abkühlung-Temperatur abgekühlt. In the subsequent recombination step, the hydrogen is preferably withdrawn from the raw form 1 at least partially, preferably completely. Preferably, the recombination step is carried out in an atmosphere comprising or consisting of a process gas, preferably hydrogen, argon, and/or helium, under a predetermined recombination pressure and a predetermined recombination temperature for a predetermined recombination period is performed. Optionally, the raw form 1 is cooled to a predetermined cooling temperature during or after the recombination step, in particular during or after step c2).
In Schritt d) wird die Rohform 1 gesintert, wobei der Permanentmagnet hergestellt wird. Vorzugsweise wird die Rohform 1 bei einem vorbestimmten Sinter-Druck, vorzugsweise mindestens 10’5 mbar absolut bis höchstens 50 mbar über Atmosphärendruck, bei einer vorbestimmten Sinter-Temperatur, vorzugsweise bei einer Temperatur von mindestens 900 °C bis höchstens 1200 °C, in einer aus einem Prozessgas, vorzugsweise Argon und/oder Helium, bestehenden Atmosphäre für eine vorbestimmte Sinter-Dauer, vorzugsweise mindestens 30 Minuten bis höchstens 240 Minuten, gesintert. In step d), the raw form 1 is sintered, the permanent magnet being produced. Preferably, the raw mold 1 is at a predetermined sintering pressure, preferably at least 10' 5 mbar absolute to a maximum of 50 mbar above atmospheric pressure, at a predetermined sintering temperature, preferably at a temperature of at least 900 ° C to a maximum of 1200 ° C, in a an atmosphere consisting of a process gas, preferably argon and/or helium, for a predetermined sintering time, preferably at least 30 minutes to a maximum of 240 minutes.
Zwischen Schritt a) und Schritt b) kann der Verfahrensschritt e) optional ausgeführt werden. In Schritt e) wird das magnetische Ausgangsmaterial mit einem organischen Binder oder einem organischen Lösungsmittel vermischt, wobei ein Gemisch aus dem magnetischen Ausgangsmaterial und dem organischen Binder oder dem organischen Lösungsmittel erhalten wird. Die Rohform 1 wird in diesem Fall in Schritt b) aus dem Gemisch erstellt. Ein organischer Binder wird vorzugsweise verwendet, falls die Rohform 1 mittels Spritzgießens erzeugt wird. Ein organisches Lösungsmittel wird vorzugsweise verwendet, falls die Rohform 1 mittels Nass- Kaltpressens erzeugt wird. Process step e) can optionally be carried out between step a) and step b). In step e), the magnetic base material is mixed with an organic binder or an organic solvent to obtain a mixture of the magnetic base material and the organic binder or the organic solvent. In this case, the raw mold 1 is created from the mixture in step b). An organic binder is preferably used if the raw mold 1 is produced by injection molding. An organic solvent is preferably used if the raw mold 1 is produced by wet cold pressing.
Falls Schritt e) ausgeführt wird, wird obligatorisch zwischen Schritt b) und Schritt c) Verfahrens schritt f) ausgeführt. In Schritt f) wird der organischer Binder oder das organische Lösungsmittel, welcher oder welches in Schritt e) zu dem magnetischen Ausgangsmaterial hinzugefügt wurde, zumindest teilweise, vorzugsweise vollständig, entfernt. If step e) is carried out, method step f) must be carried out between step b) and step c). In step f) the organic binder or the organic solvent which was added to the magnetic starting material in step e) is at least partially, preferably completely, removed.
Optional kann zwischen Schritt b) und Schritt c) oder zwischen Schritt f) und Schritt c) ein zusätzlicher Verfahrens schritt g) durchgeführt werden. In Schritt g) wird die Rohform in einer Wasserstoff aufweisenden Atmosphäre, insbesondere einer Wasserstoffatmosphäre oder in reinem Wasserstoff, vorzugsweise bei einem Druck von mindestens 50 mbar absolut bis höchstens 50 mbar über Atmosphärendruck, und vorzugsweise bei einer Temperatur von mindestens 600 °C bis höchstens 900 °C, vorzugsweise für eine Dauer von mindestens 30 Minuten bis höchstens 180 Minuten, hydriert. Optional kann nach Schritt d) ein zusätzlicher Verfahrensschritt h) - einzeln oder in Kombination mit den Verfahrens schritten e), f) und g) - durchgeführt werden. In Schritt h) wird die gesintert Rohform 1 mittels Heißisostatischen Pressens nachbehandelt, um den Permanentmagneten nachzuverdichten. Das Heißisostatische Pressen wird bei einem Druck von vorzugsweise mindestens 800 bar bis höchstens 2000 bar und einer Temperatur von vorzugsweise mindestens 900 °C bis höchstens 1200 °C für eine Dauer von vorzugsweise mindestens 30 Minuten bis höchstens 240 Minuten durchgeführt. Optionally, an additional process step g) can be carried out between step b) and step c) or between step f) and step c). In step g), the raw form is exposed in an atmosphere containing hydrogen, in particular a hydrogen atmosphere or in pure hydrogen, preferably at a pressure of at least 50 mbar absolute to at most 50 mbar above atmospheric pressure, and preferably at a temperature of at least 600° C. to at most 900 °C, preferably for a period of at least 30 minutes to at most 180 minutes. Optionally, after step d), an additional process step h) - individually or in combination with the process steps e), f) and g) - be carried out. In step h), the sintered raw form 1 is post-treated by means of hot isostatic pressing in order to post-compact the permanent magnet. The hot isostatic pressing is carried out at a pressure of preferably at least 800 bar to a maximum of 2000 bar and a temperature of preferably at least 900° C. to a maximum of 1200° C. for a period of preferably at least 30 minutes to a maximum of 240 minutes.
Fig. 2 zeigt eine schematische Darstellung einer Ausführungsform einer Kornfeinung bei einem ersten Ausführungsbeispiel einer Rohform 1. Das erste Ausführungsbeispiel einer Rohform 1 weist Partikel einer Nd2Fei4B -Legierung auf. 2 shows a schematic representation of an embodiment of grain refinement in a first embodiment of a raw mold 1. The first embodiment of a raw mold 1 has particles of an Nd2Fei4B alloy.
In Figur 2 a) ist ein Ausschnitt 3 aus einem einzigen großen Nd2Fei4B-Kom 5, als Teil des magnetischen Ausgangsmaterials, dargestellt. Das Nd2Fei4B-Kom 5 weist eine magnetische Achse 7 auf. Die in Figur 2 a) dargestellte Rohform 1 wird einem Wasserstoff-Einlagerungsschritt unterzogen. Dabei wird Wasserstoff in die Rohform 1 eingelagert und die Partikel der Nd2Fei4B- Legierung, insbesondere das dargestellte Nd2Fei4B-Kom 5, werden entsprechend der chemischen Reaktion (1) aufgespalten. FIG. 2 a) shows a section 3 from a single large Nd2Fei4B grain 5 as part of the magnetic starting material. The Nd2Fei4B-Com 5 has a magnetic axis 7 . The raw mold 1 shown in FIG. 2a) is subjected to a hydrogen storage step. In this case, hydrogen is stored in the raw form 1 and the particles of the Nd2Fei4B alloy, in particular the Nd2Fei4B grain 5 shown, are split according to the chemical reaction (1).
In Figur 2 b) ist der Ausschnitt 3 nach der chemischen Reaktion (1), insbesondere nach dem Wasserstoff-Einlagerungsschritt, dargestellt. Das Nd2Fei4B-Korn 5 wurde in eine Mehrzahl von NdHx-Kömern 9, eine Mehrzahl von Fe-Kömern 11, eine Mehrzahl von Fe2B-Körnern 13 und eine Mehrzahl von Nd2Fei4B-Körnem 15 aufgespalten. Einzig die Mehrzahl von Nd2Fei4B- Körnem 15 weist die magnetische Achse 7 auf. Die Mehrzahl von NdHx-Kömern 9, die Mehrzahl von Fe-Kömem 11 und die Mehrzahl von Fe2B-Körnem 13 weisen keine magnetische Achse auf. Vorteilhafterweise sind die NdHx-Kömer 9, die Fe-Körner 11, die Fe2B-Kömer 13 und die Nd2Fei4B-Kömer 15 jeweils kleiner als das initiale Nd2Fei4B-Korn 5. Zur übersichtlicheren Darstellung ist jeweils nur ein Korn 9, 11, 13 und 15 und eine magnetische Achse 7 mit einem Bezugszeichen versehen. Die Rohform 1 aus Figur 2 b) wird einem Rekombinationsschritt unterzogen, bei welchem der Rohform 1 der Wasserstoff zumindest teilweise, vorzugsweise komplett, entzogen wird. Der Rekombinationsschritt erfolgt entsprechend der chemischen Reaktion (2). FIG. 2 b) shows section 3 after the chemical reaction (1), in particular after the hydrogen storage step. The Nd2Fei4B grain 5 was split into a plurality of NdHx grains 9, a plurality of Fe grains 11, a plurality of Fe2B grains 13 and a plurality of Nd2Fei4B grains 15. Only the majority of Nd2Fei4B grains 15 have the magnetic axis 7 . The plurality of NdH x grains 9, the plurality of Fe grains 11, and the plurality of Fe2B grains 13 have no magnetic axis. Advantageously, the NdH x grains 9, the Fe grains 11, the Fe2B grains 13 and the Nd2Fei4B grains 15 are each smaller than the initial Nd2Fei4B grain 5. For the sake of clarity, only one grain 9, 11, 13 and 15 and a magnetic axis 7 are provided with a reference number. The raw form 1 from FIG. 2 b) is subjected to a recombination step, in which the hydrogen is at least partially, preferably completely, withdrawn from the raw form 1 . The recombination step occurs according to the chemical reaction (2).
In Figur 2 c) ist der Ausschnitt 3 nach der chemischen Reaktion (2), insbesondere nach dem Rekombinationsschritt, dargestellt. Mittels Entziehen des Wasserstoffes lagern sich die einzelnen Körner der Mehrzahl von NdHx-Körnem 9, der Mehrzahl von Fe-Körnern 11, der Mehrzahl von Fe2B-Kömem 13 und der Mehrzahl von Nd2Fei4B- Körnern 15 zusammen und bilden eine weitere Mehrzahl von neuen Nd2Fei4B-Körnem 17. Jedes Korn der Mehrzahl von Nd2Fei4B-Kömern 17 weist die magnetische Achse 7 auf. Zur übersichtlicheren Darstellung sind ein Korn 17 und eine magnetische Achse 7 mit einem Bezugszeichen versehen. Vorteilhafterweise sind die Nd2Fei4B- Kömer 17 jeweils kleiner als das initiale Nd2Fei4B-Kom 5 aus Figur 2 a). FIG. 2 c) shows section 3 after the chemical reaction (2), in particular after the recombination step. By removing the hydrogen, the individual are stored Grains of the plurality of NdH x grains 9, the plurality of Fe grains 11, the plurality of Fe2B grains 13 and the plurality of Nd2Fei4B grains 15 together and form another plurality of new Nd2Fei4B grains 17. Each grain of the plurality of Nd2Fei4B grains 17 has the magnetic axis 7. For the sake of clarity, a grain 17 and a magnetic axis 7 are provided with a reference number. The Nd2Fei4B grains 17 are advantageously each smaller than the initial Nd2Fei4B grain 5 from FIG. 2a).
Vorteilhafterweise ist die magnetische Achse 7 - bzw. die Summe der magnetischen Achsen 7 - vor, während und nach der Kornfeinung, wie in Figur 2 dargestellt, nahezu unverändert. Advantageously, the magnetic axis 7—or the sum of the magnetic axes 7—is almost unchanged before, during and after the grain refinement, as shown in FIG.
Fig. 3 zeigt eine schematische Darstellung eines zweiten Ausführungsbeispiels einer Rohform 1. Die Rohform 1 besteht aus Nd2Fei4B-Körnem 5, 17 und einer Mehrzahl von Partikeln 19 einer Seltene-Erden-reichen Phase, vorzugsweise einer Neodym-reichen Phase, welche vorzugsweise als Hydrid vorliegt. Die magnetischen Achsen 7 der Nd2Fei4B-Körner 5, 17 weisen nahezu die identische Richtung auf. Zur übersichtlicheren Darstellung ist ein Nd2Fei4B-Korn 5, 17, ein Seltene-Erden-reicher Partikel 19 und eine magnetische Achse 7 mit einem Bezugszeichen versehen. Fig. 3 shows a schematic representation of a second embodiment of a raw form 1. The raw form 1 consists of Nd2Fei4B grains 5, 17 and a plurality of particles 19 of a rare earth-rich phase, preferably a neodymium-rich phase, which is preferably a hydride present. The magnetic axes 7 of the Nd2Fei4B grains 5, 17 have almost the identical direction. For the sake of clarity, an Nd2Fei4B grain 5, 17, a rare earth-rich particle 19 and a magnetic axis 7 are provided with a reference number.

Claims

ANSPRÜCHE EXPECTATIONS
1. Verfahren zur Herstellung eines Permanentmagneten aus einem magnetischen Ausgangsmaterial, wobei 1. A method for producing a permanent magnet from a magnetic starting material, wherein
- das magnetische Ausgangsmaterial in Form gebracht wird, wobei eine Rohform (1) erstellt wird, wobei - The magnetic starting material is brought into shape, with a raw form (1) being created, wherein
- die Rohform (1) einer Kornfeinung unterzogen wird, wobei - The raw form (1) is subjected to a grain refinement, wherein
- die Rohform (1) gesintert wird, wobei der Permanentmagnet hergestellt wird. - The raw form (1) is sintered, the permanent magnet being produced.
2. Verfahren nach Anspruch 1, wobei als magnetisches Ausgangsmaterial ein Material verwendet wird, das Partikel einer RxTyB -Legierung und vorzugsweise Partikel einer Seltene-Erden-reichen Phase aufweist. 2. The method according to claim 1, wherein a material is used as the magnetic starting material, the particles of an R x T y B alloy and preferably particles of a rare earth-rich phase.
3. Verfahren nach einem der vorhergehenden Ansprüche, wobei 3. The method according to any one of the preceding claims, wherein
- das magnetische Ausgangsmaterial mit einem organischen Binder vermischt wird, wobei - The magnetic starting material is mixed with an organic binder, wherein
- ein Gemisch aus dem magnetischen Ausgangsmaterial und dem organischen Binder erhalten wird, wobei - A mixture of the magnetic starting material and the organic binder is obtained, wherein
- die Rohform (1) aus dem Gemisch erstellt wird, wobei - The raw form (1) is created from the mixture, wherein
- der organische Binder vor der Kornfeinung zumindest teilweise, vorzugsweise komplett, aus der Rohform (1) entfernt wird. - the organic binder is at least partially, preferably completely, removed from the raw mold (1) before grain refinement.
4. Verfahren nach einem der vorhergehenden Ansprüche, wobei 4. The method according to any one of the preceding claims, wherein
- das magnetische Ausgangsmaterial mit einem organischen Lösungsmittel vermischt wird, wobei - The magnetic starting material is mixed with an organic solvent, wherein
- ein Gemisch aus dem magnetischen Ausgangsmaterial und dem organischen Lösungsmittel erhalten wird, wobei - die Rohform (1) aus dem Gemisch erstellt wird, wobei - a mixture of the magnetic starting material and the organic solvent is obtained, wherein - The raw form (1) is created from the mixture, wherein
- das organische Lösungsmittel vor der Kornfeinung zumindest teilweise, vorzugsweise komplett, aus der Rohform (1) entfernt wird. Verfahren nach einem der vorhergehenden Ansprüche, wobei - the organic solvent is at least partially, preferably completely, removed from the raw mold (1) before grain refinement. Method according to one of the preceding claims, wherein
- die Kornfeinung einen Wasserstoff-Einlagerungsschritt und einen Rekombinations schritt aufweist, wobei - The grain refinement has a hydrogen storage step and a recombination step, wherein
- in dem Wasserstoff-Einlagerungsschritt die Rohform (1), insbesondere die Partikel des magnetischen Ausgangsmaterials, aus welchen die Rohform (1) besteht, mit Wasserstoff zur Reaktion gebracht wird, wobei - In the hydrogen storage step, the raw form (1), in particular the particles of the magnetic starting material, of which the raw form (1) consists, is reacted with hydrogen, wherein
- in dem Rekombinationsschritt der Wasserstoff zumindest teilweise, vorzugsweise komplett, entzogen wird. Verfahren nach einem der vorhergehenden Ansprüche, wobei der Wasserstoff-- In the recombination step, the hydrogen is at least partially, preferably completely, withdrawn. Method according to any one of the preceding claims, wherein the hydrogen
Einlagerungsschritt in einer Wasserstoff aufweisenden Atmosphäre unter einem vorbestimmten Einlagerung s -Druck für eine vorbestimmte Einlagerung s -Dauer durchgeführt wird, wobei die Rohform (1) während des Wasserstoff-Einlagerungsschritt auf eine vorbestimmte Einlagerungs-Temperatur erhitzt wird. Verfahren nach einem der vorhergehenden Ansprüche, wobei der Rekombinationsschritt in einer ein Verfahrensgas aufweisenden oder aus dem Verfahrensgas bestehenden Atmosphäre unter einem vorbestimmten Rekombinations-Druck und einer vorbestimmten Rekombinations-Temperatur für eine vorbestimmte Rekombinations-Dauer durchgeführt wird. Verfahren nach einem der vorhergehenden Ansprüche, wobei das Verfahrensgas ausgewählt ist aus einer Gruppe, bestehend aus Wasserstoff, Argon, und Helium. Verfahren nach einem der vorhergehenden Ansprüche, wobei die Rohform (1) während oder nach dem Rekombinationsschritt auf eine vorbestimmte Abkühl-Temperatur abgekühlt wird 19 embedding step is carried out in an atmosphere comprising hydrogen under a predetermined embedding s pressure for a predetermined embedding s duration, wherein the raw mold (1) is heated to a predetermined embedding temperature during the hydrogen embedding step. A method according to any one of the preceding claims, wherein the recombination step is carried out in an atmosphere comprising or consisting of a process gas under a predetermined recombination pressure and temperature for a predetermined recombination time. A method according to any one of the preceding claims, wherein the process gas is selected from a group consisting of hydrogen, argon, and helium. Method according to one of the preceding claims, in which the raw mold (1) is cooled to a predetermined cooling temperature during or after the recombination step 19
10. Verfahren nach einem der vorhergehenden Ansprüche, wobei die Rohform (1) mittels eines Verfahrens, ausgewählt aus einer Gruppe, bestehend aus Spritzgießen, additivem Fertigen, Extrudieren, Kaltpressen, und Heißpressen, hergestellt wird. 10. The method according to any one of the preceding claims, wherein the raw mold (1) is produced by a method selected from a group consisting of injection molding, additive manufacturing, extrusion, cold pressing, and hot pressing.
11. Verfahren nach einem der vorhergehenden Ansprüche, wobei die Rohform (1) in einem extern anliegenden Magnetfeld hergestellt wird. 11. The method according to any one of the preceding claims, wherein the raw mold (1) is produced in an externally applied magnetic field.
12. Verfahren nach einem der vorhergehenden Ansprüche, wobei die Rohform (1) bei einem vorbestimmten Sinter-Druck und bei einer vorbestimmten Sinter-Temperatur, vorzugsweise einer Temperatur von mindestens 900 °C bis höchstens 1200 °C, in einer aus einem Prozessgas bestehenden Atmosphäre für eine vorbestimmte Sinter-Dauer gesintert wird. 12. The method according to any one of the preceding claims, wherein the raw mold (1) at a predetermined sintering pressure and at a predetermined sintering temperature, preferably a temperature of at least 900 °C to at most 1200 °C, in an atmosphere consisting of a process gas is sintered for a predetermined sintering time.
13. Verfahren nach einem der vorhergehenden Ansprüche, wobei das Prozessgas ausgewählt ist aus einer Gruppe, bestehend aus Argon und Helium. 13. The method according to any one of the preceding claims, wherein the process gas is selected from a group consisting of argon and helium.
14. Verfahren nach einem der vorherigen Ansprüche, wobei die gesendete Rohform (1) mittels Heißisostatischen Pressens nachbehandelt wird. 14. The method according to any one of the preceding claims, wherein the sent raw form (1) is post-treated by means of hot isostatic pressing.
EP21814732.0A 2020-11-13 2021-11-12 Method for producing a permanent magnet from a magnetic starting material Pending EP4244876A1 (en)

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DE102020214335.8A DE102020214335A1 (en) 2020-11-13 2020-11-13 Process for producing a permanent magnet from a magnetic starting material
PCT/EP2021/081593 WO2022101447A1 (en) 2020-11-13 2021-11-12 Method for producing a permanent magnet from a magnetic starting material

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DE19843883C1 (en) 1998-09-24 1999-10-07 Vacuumschmelze Gmbh Method for recycling of permanent magnets forming part of scrap material
US8268093B2 (en) * 2006-05-18 2012-09-18 Hitachi Metals, Ltd. R-Fe-B porous magnet and method for producing the same
EP2043114B1 (en) * 2006-11-30 2019-01-02 Hitachi Metals, Ltd. R-fe-b microcrystalline high-density magnet and process for production thereof
US9663843B2 (en) 2010-12-02 2017-05-30 The University Of Birmingham Magnet recycling
HUE053709T2 (en) 2011-06-24 2021-07-28 Nitto Denko Corp Production method for rare earth permanent magnet
GB201511553D0 (en) 2015-07-01 2015-08-12 Univ Birmingham Magnet production
ES2968229T3 (en) 2015-09-28 2024-05-08 Mimplus Tech Gmbh & Co Kg Procedure to make a permanent magnet
KR102045402B1 (en) * 2018-04-30 2019-11-15 성림첨단산업(주) Manufacturing method of rare earth sintered magnet

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