Method for producing a raw magnet

Abstract

The invention relates to a method for producing a raw magnet (4), wherein - a first raw shape (2.1) is produced from a first magnetic starting material (1.1), - a second raw shape (2.2) is produced from a second magnetic starting material (1.2), - an external magnetic field (21) is applied to at least one raw shape (2), selected from a group consisting of the first raw shape (2.1) and the second raw shape (2.2), during and / or after the raw shape (2) is produced, - a third raw shape (3) is produced from the first raw shape (2.1) and the second raw shape (2.2) by means of joining said raw shapes to one another, - the third raw shape (3) is sintered, and the raw magnet (4) is obtained.

Description

[0001] The invention relates to a method for producing a raw magnet.

[0002] Permanent magnets from the rare earth group are used in a wide variety of technical applications and are characterized by a particularly high energy product. Neodymium-iron-boron magnets, in particular, exhibit an energy product of up to 400 kJ / m³.

[0003] Known methods for manufacturing a permanent magnet include producing, in particular pressing, a raw shape and subsequently sintering the raw shape. A disadvantage of these methods is that only simple magnet shapes, especially cylinders or cuboids, and / or simple magnetizations, especially axial magnetization, are achievable. A magnet shape and / or magnetization adapted to a specific requirement is therefore not possible.

[0004] Methods for creating complex magnet shapes and / or complex magnetizations are known in which at least two magnetized magnets are joined together. A disadvantage of these methods is that they are very cumbersome and time-consuming due to the mutual attraction of the magnets. Furthermore, the magnets can be damaged, and a worker can be injured, particularly by crushing injuries, if the magnets collide uncontrollably due to their mutual attraction.

[0005] Furthermore, mechanically fixing a magnet containing at least one rare-earth element within an assembly is not possible. This is due, among other things, to the magnet's simple shape and the fact that threads and bores cannot be produced using press sintering. Machining the magnet is also difficult because it is extremely brittle and should be avoided to ensure efficient resource utilization.

[0006] Methods are known for fixing magnets, particularly in an assembly, in which the magnets are glued into the assembly or encapsulated or overmolded with an impregnating resin. A disadvantage of these methods is that assembly is very complex and that the adhesive and / or impregnating resin can cause corrosion of the magnet.

[0007] US 2017 / 154713 shows the additive manufacturing of magnets, where the magnetic orientation can be adjusted. DE 10 2011 105324 shows the injection molding of magnets in one piece with Halbach-like iteration of the poles.

[0008] The invention is therefore based on the objective of creating a method for producing a raw magnet, in particular for producing a permanent magnet, wherein the aforementioned disadvantages, especially with regard to the permanent magnet to be produced, are at least partially eliminated, preferably avoided.

[0009] The problem is solved by providing the present technical teaching, in particular the teaching of independent claim 1 and of the embodiments disclosed in the dependent claims and the description.

[0010] The problem is solved, in particular, by providing a method for producing a raw magnet, wherein a first raw shape is produced from a first magnetic starting material and a second raw shape is produced from a second magnetic starting material. Furthermore, an external magnetic field is applied to at least one raw shape, selected from a group consisting of the first and second raw shapes, during its production. Alternatively or additionally, an external magnetic field is applied to the at least one raw shape after its production. Subsequently, a third raw shape is produced by joining the first and second raw shapes together. The third raw shape is then sintered, yielding the raw magnet.

[0011] Advantageously, this method is suitable for producing permanent magnets with complex shapes and / or magnetizations, obtained after magnetizing raw magnets. The resulting permanent magnet preferably has a shape and / or magnetization that can be tailored to specific requirements. Furthermore, little or no post-processing of the raw magnet is necessary. Additionally, the sintering of the third raw shape advantageously creates a metallurgical bond between the first and second raw shapes.

[0012] Advantageously, dipoles of the magnetic starting material are aligned in a parallel orientation by means of the externally applied magnetic field during and / or after the production of the at least one raw form.

[0013] Preferably, the externally applied magnetic field is generated by a switchable electromagnet and / or a permanent magnet.

[0014] In one embodiment, the third raw form is formed from a plurality of raw forms, in particular from a plurality of first raw forms and / or a plurality of second raw forms.

[0015] In one embodiment, the at least one raw mold, in particular exactly one raw mold, selected from a group consisting of the first raw mold and the second raw mold, is produced in the externally applied magnetic field. Advantageously, the particles of the magnetic starting material from which the at least one raw mold is produced align themselves according to the externally applied magnetic field during the production of the at least one raw mold. Preferably, the magnetic starting material of the at least one raw mold, in particular exactly one raw mold, is hard magnetic. In particular, the external magnetic field is applied to the at least one raw mold, in particular exactly one raw mold, only during the production of the at least one raw mold, in particular exactly one raw mold.In particular, the external magnetic field is not applied to the at least one raw mold, especially the exactly one raw mold, after the production of the at least one raw mold, especially the exactly one raw mold.

[0016] In a further embodiment, the external magnetic field is applied to the at least one raw mold, in particular to exactly one raw mold selected from a group consisting of the first raw mold and the second raw mold, after the production of the at least one raw mold, in particular to exactly one raw mold. In particular, the external magnetic field is applied to the at least one raw mold, in particular to exactly one raw mold, only after the production of the at least one raw mold, in particular to exactly one raw mold. In particular, the external magnetic field is not applied to the at least one raw mold, in particular to exactly one raw mold, during the production of the at least one raw mold, in particular to exactly one raw mold.

[0017] In a further embodiment, the external magnetic field is applied to at least one raw mold, in particular to exactly one raw mold selected from a group consisting of the first raw mold and the second raw mold, during and after the production of the raw mold, in particular the exactly one raw mold.

[0018] In a further embodiment, the first and second raw forms are produced in the externally applied magnetic field. Specifically, the external magnetic field is applied to the first raw form only during its production. Additionally, the external magnetic field is applied to the second raw form only during its production. Specifically, the external magnetic field is not applied to the first raw form after its production. Additionally, the external magnetic field is not applied to the second raw form after its production.

[0019] In a further embodiment, the external magnetic field is applied to the first and second raw molds after their production. Specifically, the external magnetic field is applied to the first raw mold only after its production. Additionally, the external magnetic field is applied to the second raw mold only after its production. Specifically, the external magnetic field is not applied to the first raw mold during its production. Additionally, the external magnetic field is not applied to the second raw mold during its production.

[0020] In a further embodiment, the first raw mold is produced in the externally applied magnetic field. Additionally, the external magnetic field is applied to the second raw mold after its production. Specifically, the external magnetic field is applied to the first raw mold only during its production. Specifically, the external magnetic field is not applied to the first raw mold after its production. Additionally, specifically, the external magnetic field is applied to the second raw mold only after its production. Specifically, the external magnetic field is not applied to the second raw mold during its production.

[0021] In a further embodiment, the second raw mold is produced in the externally applied magnetic field. Additionally, the external magnetic field is applied to the first raw mold after its production. Specifically, the external magnetic field is applied to the second raw mold only during its production. Specifically, the external magnetic field is not applied to the second raw mold after its production. Additionally, specifically, the external magnetic field is applied to the first raw mold only after its production. Specifically, the external magnetic field is not applied to the first raw mold during its production.

[0022] In a further embodiment, an external magnetic field is applied to the first raw mold during and after its production. Additionally, an external magnetic field is applied to the second raw mold during and after its production. Furthermore, and particularly preferably, the second raw mold is heated to its softening temperature while the external magnetic field is applied.

[0023] Advantageously, the process is suitable for powdered magnetic starting materials formed from a newly melted alloy, particularly in the form of a cast ingot or as melt-spun material. Alternatively or additionally, the process is suitable for recycled magnetic material and / or contaminated recycled magnetic material. Furthermore, material obtained through recycling is preferably alloyed with at least one rare-earth element, preferably in powder form, to improve its properties.

[0024] The first magnetic starting material and / or the second magnetic starting material are preferably in a pure form or in a hydrogenated form. US patent application US 2013 / 0263699 A1 and German patent DE 198 43 883 C1 describe a process called hydrogen decrepitation (HD) for producing a hydrogenated form of the first magnetic starting material and / or the second magnetic starting material by means of hydrogen-induced decay.

[0025] Preferably, a magnetic pre-material is mechanically reduced, in particular by grinding, to a particle size of at least 1 µm to at most 200 µm in order to obtain a powdered magnetic starting material selected from the first magnetic starting material and the second magnetic starting material.

[0026] Preferably, the first magnetic starting material and the second magnetic starting material are identical. Alternatively, the first magnetic starting material and the second magnetic starting material are different, in particular, the first magnetic starting material and the second magnetic starting material differ in at least one property selected from a group consisting of a particle size, a particle shape, a particle size distribution, and a chemical composition.

[0027] Preferably, the raw magnet is magnetized, resulting in a permanent magnet. The method is then, in particular, a method for producing a permanent magnet.

[0028] According to a further development of the invention, the first magnetic starting material and / or the second magnetic starting material is a material comprising particles of an R x T y B alloy. Preferably, the first magnetic starting material and / or the second magnetic starting material is a material consisting of particles of an R x T y B alloy. In particular, the first magnetic starting material and / or the second magnetic starting material is preferably a material comprising or consisting of particles of an Nd x Fe y B alloy.

[0029] Preferably, the first magnetic starting material and / or the second magnetic starting material is a material comprising particles of an R x T y B alloy and particles of a rare-earth-rich phase. In particular, the first magnetic starting material and / or the second magnetic starting material preferably consists of a mixture of particles of an R x T y B alloy and particles of a rare-earth-rich phase. Preferably, the first magnetic starting material and / or the second magnetic starting material is a material comprising or consisting of particles of an Nd x Fe y B alloy and particles of a neodymium-rich phase. In particular, the first magnetic starting material and / or the second magnetic starting material preferably comprises or consists of a mixture of particles of an Nd x Fe y B alloy and particles of a neodymium-rich phase.

[0030] In the context of this technical teaching, R represents a rare-earth element, that is, an element from the rare-earth group, T represents at least one element selected from the group consisting of iron and cobalt, and B represents the element boron. In particular, the elements iron and cobalt partially or completely substitute for one another 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 another element, preferably a metal, in particular a transition metal, selected from the group consisting of aluminum, copper, zirconium, gallium, hafnium, and niobium, preferably in trace amounts.

[0031] Preferably, the first magnetic starting material and / or the second magnetic starting material comprises particles of an Nd 2 Fe 14 B alloy or consists of particles of an Nd 2 Fe 14 B alloy.

[0032] Preferably, the rare-earth-rich phase, in particular the neodymium-rich phase, comprises at least one rare-earth element, in particular neodymium, or a chemical compound of this rare-earth element, in particular neodymium. Additionally, the rare-earth-rich phase, in particular the neodymium-rich phase, preferably contains at least one further element of the RxTyB alloy, in particular the NdxFeyB alloy. Alternatively or additionally, the at least one rare-earth element, in particular neodymium, is present in a hydrogenated form. Preferably, the neodymium-rich phase comprises or consists of NdH₂ and / or NdH₂,7. Alternatively, in a preferred embodiment, the rare-earth-rich phase, in particular the neodymium-rich phase, consists of at least one rare-earth element, in particular neodymium, or of a chemical compound of this rare-earth element, in particular neodymium.

[0033] Alternatively, preferably the at least one rare earth element, in particular neodymium, in a hydrogenated form, in particular NdH 2 and / or NdH 2,7, is additionally added to the magnetic starting material.

[0034] The rare-earth-rich phase preferentially forms a phase within the microstructure of the raw magnet, located at the grain boundaries. In particular, the rare-earth-rich phase is enriched at these grain boundaries. Specifically, the rare-earth-rich phase is inhomogeneously distributed within the microstructure.

[0035] According to a further development of the invention, it is provided that the first magnetic starting material and / or the second magnetic starting material is a material which has at least one compound selected from a group consisting of an aluminum-nickel-cobalt alloy, a samarium-cobalt alloy, and a ferrite alloy.

[0036] Preferably, the first magnetic starting material and / or the second magnetic starting material is a material consisting of at least one compound selected from a group consisting of an aluminum-nickel-cobalt alloy, a samarium-cobalt alloy, and a ferrite alloy.

[0037] In one embodiment of the method, a samarium-cobalt alloy comprising SmCo 5, preferably consisting of SmCo 5, is used as the first magnetic starting material and / or as the second magnetic starting material.

[0038] In a further embodiment of the method, a samarium-cobalt alloy comprising Sm 2 Co 17 , iron, copper and zirconium, preferably consisting of Sm 2 Co 17 , iron, copper and zirconium, is used as the first magnetic starting material and / or as the second magnetic starting material.

[0039] In a further preferred embodiment of the method, the first magnetic starting material and / or the second magnetic starting material is a material comprising an iron oxide, in particular Fe₂O₃, and at least one metal oxide, in particular nickel oxide, zinc oxide, manganese oxide, cobalt oxide, copper oxide, magnesium oxide, cadmium oxide, barium oxide, or strontium oxide. Preferably, the material consists of an iron oxide, in particular Fe₂O₃, and at least one metal oxide, in particular nickel oxide, zinc oxide, manganese oxide, cobalt oxide, copper oxide, magnesium oxide, cadmium oxide, barium oxide, or strontium oxide. Particularly preferably, the material is selected from the group consisting of a manganese-zinc ferrite, a nickel-zinc ferrite, a strontium ferrite, a barium ferrite, and a cobalt ferrite.

[0040] According to a further development of the invention, a first external magnetic field is applied to the first raw mold during and / or after its production. Furthermore, a second external magnetic field is applied to the second raw mold during and / or after its production. Preferably, the first external magnetic field and the second external magnetic field differ from each other; in particular, the first external magnetic field and the second external magnetic field are not identical.

[0041] In one embodiment of the method, the first raw mold is produced in the first externally applied magnetic field. Additionally, the second raw mold is produced in the second externally applied magnetic field. Specifically, the first external magnetic field is applied to the first raw mold only during its production. Specifically, the first external magnetic field is not applied to the first raw mold after its production. Additionally, specifically, the second external magnetic field is applied to the second raw mold only during its production. Specifically, the second external magnetic field is not applied to the second raw mold after its production.

[0042] In a further embodiment of the method, the first external magnetic field is applied to the first raw mold after its production. Additionally, the second external magnetic field is applied to the second raw mold after its production. In particular, the first external magnetic field is applied to the first raw mold only after its production. In particular, the first external magnetic field is not applied to the first raw mold during its production. Additionally, the second external magnetic field is applied to the second raw mold only after its production. In particular, the second external magnetic field is not applied to the second raw mold during its production.

[0043] In a further embodiment of the method, the first raw mold is produced in the first externally applied magnetic field. Additionally, the second external magnetic field is applied to the second raw mold after its production. In particular, the first external magnetic field is applied to the first raw mold only during its production. In particular, the first external magnetic field is not applied to the first raw mold after its production. Additionally, in particular, the second external magnetic field is applied to the second raw mold only after its production. In particular, the second external magnetic field is not applied to the second raw mold during its production.

[0044] In a further embodiment of the method, the first external magnetic field is applied to the first raw mold after its production. Additionally, the second raw mold is produced in the second externally applied magnetic field. In particular, the first external magnetic field is applied to the first raw mold only after its production. In particular, the first external magnetic field is not applied to the first raw mold during its production. Additionally, the second external magnetic field is applied to the second raw mold only during its production. In particular, the second external magnetic field is not applied to the second raw mold after its production.

[0045] According to a further development of the invention, the first magnetic starting material is mixed with a first binder, yielding a first mixture of the first magnetic starting material and the first binder. Furthermore, the second magnetic starting material is mixed with a second binder, yielding a second mixture of the second magnetic starting material and the second binder. The first raw form is produced from the first mixture, and the second raw form is produced from the second mixture.

[0046] Additionally, after the production of the third raw mold, the first binder and the second binder are at least partially, preferably completely, removed from the third raw mold. Alternatively, before the production of the third raw mold, the first binder and / or the second binder are at least partially, preferably completely, removed from the first raw mold and / or the second raw mold.

[0047] In one embodiment of the process, the first mixture comprises a volume fraction of at least 45% to at most 75% of the first magnetic starting material and a volume fraction of at least 25% to at most 55% of the first binder. Alternatively or additionally, the second mixture comprises a volume fraction of at least 45% to at most 75% of the second magnetic starting material and a volume fraction of at least 25% to at most 45% of the second binder. The first binder and / or second binder preferably comprises at least one organic binder component.

[0048] Preferably, the first mixture and the second mixture are identical. Alternatively, the first mixture and the second mixture are different, in particular, the first mixture and the second mixture have different components and / or different weight proportions of the individual components.

[0049] Preferably, the first raw mold is heated to a first softening temperature, in particular the first softening temperature of the first mixture, while the external magnetic field is applied. Alternatively or additionally, the second raw mold is heated to a second softening temperature, in particular the second softening temperature of the second mixture, while the external magnetic field is applied.

[0050] In a further embodiment of the process, the first and second binders are at least partially removed from the third raw form by means of a solvent or a chemical process. Optionally, a remaining portion of the first and second binders is also removed from the third raw form by thermal decomposition, particularly directly before sintering.

[0051] According to a further development of the invention, a first main component of the first binder and a second main component of the second binder are identical. Advantageously, this makes it possible to achieve a metallurgical bond between the first and second raw forms, in particular between the first and second binders, during the production of the third raw form by joining.

[0052] In one embodiment of the method, the first binder and the second binder are identical.

[0053] According to a further development of the invention, it is provided that at least one raw form, selected from the first raw form and the second 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, dry pressing, and wet pressing.

[0054] In one embodiment of the method, the first raw shape is produced by injection molding the first mixture, which comprises the first magnetic starting material and the first binder. Alternatively or additionally, the second raw shape is produced by injection molding the second mixture, which comprises the second magnetic starting material and the second binder.

[0055] In a further embodiment of the process, at least one raw form, selected from the first and second raw forms, is produced by cold pressing a magnetic starting material. During cold pressing, the particles are mechanically interlocked, particularly under a pressure of up to 1 GPa. In dry cold pressing, no additional liquid component is added to the magnetic starting material. In wet cold pressing, at least one organic solvent, preferably a volatile organic solvent, is added to the magnetic starting material. The volatile organic solvent is selected from the group consisting of an alcohol, an aliphatic compound, an acyclic alkane, a cyclic alkane, a ketone, an alkene, an aromatic compound, and a mixture of volatile organic substances that can serve as solvents. Ethanol or isopropanol is preferably used as the alcohol.Cyclohexane is preferably used as the cyclic alkane. Acetone is preferably used as the ketone. Benzene, xylene, and / or toluene are preferably used as the aromatic compound. The mixture of volatile organic substances is preferably selected from the group consisting of petroleum, white spirit, and naphtha. The organic solvent serves as a binder in wet-cold pressing. Furthermore, the first crude form and / or the second crude form is preferably dried before sintering.

[0056] In another embodiment of the method, the first raw form and the second raw form are produced using the identical method.

[0057] According to a further development of the invention, the second raw form is injection-molded onto the first raw form, in particular by injection molding of the second mixture. The third raw form is thereby produced.

[0058] Preferably, at least one magnetic starting material, selected from a group consisting of the first magnetic starting material and the second magnetic starting material, comprises a hard magnetic material; in particular, the at least one magnetic starting material comprises a hard magnetic material. In particular, the hard magnetic material is an R x T y B alloy. Additionally, at least one magnetic starting material, selected from a group consisting of the first magnetic starting material and the second magnetic starting material, comprises a soft magnetic or a paramagnetic material; in particular, the at most one magnetic starting material comprises a soft magnetic or paramagnetic material.Preferably, the first magnetic starting material is a hard magnetic material or consists of a hard magnetic material, and the second magnetic starting material is a soft magnetic or paramagnetic material or consists of a soft magnetic or paramagnetic material. Advantageously, a soft magnetic or paramagnetic material can be easily post-processed after sintering, in particular by machining.

[0059] In a preferred embodiment of the method, the first and second blanks are produced by injection molding, wherein the first blank is at least partially overmolded with the second mixture. To produce the first blank, the first mixture is injected into a first cavity of a mold. After the first blank has cooled and / or solidified, it is placed in a second cavity of the mold and overmolded with the second mixture, producing the second blank, which preferably encloses the first blank, at least partially. The first and second blanks together form the third blank. As the second mixture solidifies, the volume of the second blank decreases. Therefore, the second blank shrinks upon solidification, forming a force-fit connection between the first and second blanks.Additionally, depending on the geometry of the first and second raw molds, a positive-locking connection between them is achieved. This process is advantageously applicable to a multiple of raw molds.

[0060] According to a further development of the invention, the third raw form is produced by means of a method selected from a group consisting of material-bonding joining, in particular gluing, form-fitting joining, force-fitting joining and loose joining.

[0061] In one embodiment of the method, the third raw form is produced by material bonding. Preferably, the first binder and the second binder have at least one identical binder component. Preferably, the at least one identical binder component is a thermoplastic. Furthermore, the at least one identical binder component is the first main component of the first binder and the second main component of the second binder. Particularly preferably, at least one magnetic starting material, selected from a group consisting of the first magnetic starting material and the second magnetic starting material, is a hard magnetic material.

[0062] In a first embodiment of the material-bonded joining process, a first joining surface of the first raw form and a second joining surface of the second raw form are heated to a temperature of at least 35 °C to a maximum of 230 °C, preferably at least 70 °C to a maximum of 200 °C, particularly by means of a hot plate or a laser, whereby the first joining surface and the second joining surface are melted. Once the first joining surface and the second joining surface have melted, they are pressed together with a pressure of at least 0.001 MPa to a maximum of 10 MPa until the molten joining surfaces have solidified again, whereby the first raw form and the second raw form are materially bonded to each other to form the third raw form.

[0063] In a second embodiment of material joining, the first joining surface and the second joining surface are materially joined together by friction welding, whereby the third raw form is produced.

[0064] In a third embodiment of the material-bonded joining process, the third raw form is produced by adhesive bonding. It is particularly preferred that the first and second raw forms are joined using a physically and / or chemically curing adhesive.

[0065] In one embodiment of the bonding process, a hot melt adhesive that physically cures is used. Preferably, at least one binder is melted and used as an adhesive to join the first and second raw parts. The hot melt adhesive preferably comprises at least one magnetic starting material, particularly in powder form.

[0066] In another embodiment of the bonding process, an adhesive comprising at least one polymer dissolved in a solvent is used to join the first and second raw material forms. In particular, the solvent in the adhesive evaporates, resulting in an adhesive effect.

[0067] In another embodiment of the bonding process, an adhesive selected from a group consisting of a cyanoacrylate, an epoxy adhesive, and a phenolic resin is used to join the first raw form and the second raw form together.

[0068] In a further embodiment of the method, the third blank is produced by means of positive locking. Preferably, the first blank and the second blank can be positively locked together via their respective geometries, in particular via a tongue-and-groove geometry, a screw-thread geometry, or a pin-bore geometry. Preferably, at least one magnetic starting material, selected from a group consisting of the first magnetic starting material and the second magnetic starting material, is a hard magnetic material.

[0069] In one embodiment of positive locking, a geometry that enables a positive locking connection is formed during the production of the first raw form and the second raw form.

[0070] In another embodiment of the positive locking connection, the geometry that enables the positive locking connection is formed after the production of the first raw form and the second raw form, in particular by means of machining.

[0071] In another embodiment of the positive locking connection, the geometry that enables the positive locking connection is formed during the production of the first raw form and after the production of the second raw form, in particular by means of machining.

[0072] In a further embodiment of the method, the third raw form is produced by means of force-fit connection, in particular by means of a thread or an interference fit. Preferably, at least one magnetic starting material, selected from a group consisting of the first magnetic starting material and the second magnetic starting material, is a hard magnetic material.

[0073] In a further embodiment of the method, the third raw form is produced by loosely joining the first and second raw forms. Advantageously, loosely joining the first and second raw forms after sintering creates a force-fit and / or material-fit connection for the resulting raw magnet. Preferably, at least one magnetic starting material, selected from a group consisting of the first magnetic starting material and the second magnetic starting material, is a hard magnetic material.

[0074] In one embodiment of the loose joining process, the first blank has a recess in which the second blank is positioned. Preferably, the recess has a larger dimension than the second blank. In particular, the first blank exhibits a first volume shrinkage of at least 15% and at most 20% during sintering. Additionally, the second blank exhibits a second volume shrinkage of at least 15% and at most 20% during sintering. Furthermore, the second volume shrinkage is, in particular, less than the first volume shrinkage.Advantageously, during sintering, the second raw form is clamped into the recess of the first raw form by force due to the second volume shrinkage, which is less than the first volume shrinkage of the first raw form. In addition, a first connecting surface of the first raw form, which corresponds to the surface of the recess, and the second raw form, which is arranged in the recess, bond together during sintering.

[0075] In particular, if the first raw form is produced from the first mixture and the second raw form from the second mixture, the first volume shrinkage and the second volume shrinkage, which differs from the first volume shrinkage, are achieved by a first proportion of the first magnetic starting material in the first mixture differing from a second proportion of the second magnetic starting material in the second mixture.

[0076] Alternatively or additionally, if the first blank is made from the first magnetic starting material and the second blank is made from the second magnetic starting material, the first volume shrinkage and the second volume shrinkage, which differs from the first volume shrinkage, are achieved by differentiating a first blank density, which is obtained in particular during dry pressing with a first pressure, from a second blank density, which is obtained in particular during dry pressing with a second pressure that differs from the first pressure.

[0077] In a further embodiment of the loose joining process, the first and second raw forms are loosely layered to produce the third raw form, with a metallurgical bond being formed between the first and second raw forms during sintering. Particularly preferably, a metal foil, especially a stainless steel foil, is layered, particularly loosely, between the first and second raw forms before sintering. Alternatively or additionally, a ceramic foil is layered, particularly loosely, between the first and second raw forms before sintering. Alternatively or additionally, a plurality of first raw forms and / or a plurality of second raw forms are loosely layered to produce the third raw form.

[0078] According to a further development of the invention, the first binder and the second binder comprise at least one substance selected from the group consisting of polyoxymethylene, polypropylene, paraffin wax, polyethylene, and polyamide. Advantageously, polyoxymethylene, polypropylene, paraffin wax, polyethylene, and polyamide are thermoplastics and are therefore suitable for forming a metallurgical bond between the first and second raw materials. Furthermore, the at least one substance selected from the group consisting of polyoxymethylene, polypropylene, paraffin wax, polyethylene, and polyamide facilitates the alignment of the particles of the first magnetic starting material and the second magnetic starting material.

[0079] According to a further development of the invention, a separating layer is arranged, and in particular inserted, between the first joining surface of the first raw form and the second joining surface of the second raw form. Advantageously, the separating layer prevents a material-bonded connection between the first and second raw forms. Preferably, due to the separating layer, especially during loose joining, only a force-fit connection is formed between the first and second raw forms.

[0080] Advantageously, the separating layer makes it possible to separate the first and second raw forms with respect to at least one chemical and / or physical property of the raw forms and, in particular, of the permanent magnet. Specifically, the first and second connecting surfaces face each other and are separated by the separating layer, or at least separated with respect to at least one property.

[0081] In a further embodiment of the method, the separating layer is configured as at least one closed, i.e., in particular a continuous, separating layer. Alternatively, the separating layer is configured as a non-closed or partially open separating layer, in particular as a plurality of partially present separating layer fragments. Alternatively, the separating layer is configured in the form of particles on at least one interface, selected from the first interface and the second interface.

[0082] According to a further development of the invention, it is provided that a material is used as the separating layer which comprises at least one compound selected from a group consisting of aluminium oxide, zirconium oxide, yttrium oxide, and at least one rare earth oxide.

[0083] Preferably, a separating layer is used consisting of at least one compound selected from the group comprising aluminium oxide, zirconium oxide, yttrium oxide, and at least one rare earth oxide.

[0084] According to a further development of the invention, the third raw form is at least partially, preferably completely, debound. Preferably, during debinding, the at least one binder component is at least partially, preferably completely, removed from the third raw form.

[0085] Preferably, the third raw form is partially debound using a solvent. Subsequently, thermal debinding is preferably carried out, in particular, the thermal debinding is carried out before sintering.

[0086] Alternatively, the third raw form is completely debound using a solvent, in particular, the third raw form is debound before sintering.

[0087] According to a further development of the invention, the third raw form is sintered in an atmosphere containing at least one process gas selected from the group consisting of argon and helium. Particularly preferably, the atmosphere in which the third raw form is sintered consists of at least one process gas selected from the group consisting of argon and helium. Alternatively, the third raw form is preferably sintered in a vacuum.

[0088] According to a further development of the invention, a Halbach array is produced as the raw magnet. The first raw form is manufactured by injection molding in an externally applied magnetic field that exhibits a magnetic field orientation. The first raw form is then rotated such that the particle orientation within it is orthogonal to the magnetic field orientation. Subsequently, the second raw form is injection molded onto the rotated first raw form in the same externally applied magnetic field. Advantageously, this method allows for the simple and efficient production of a Halbach array, particularly in a magnet shape adapted to the application.

[0089] Preferably, the first mold is rotated only after it has solidified. Alternatively or additionally, the external magnetic field is not applied to the first mold during rotation.

[0090] Preferably, the second raw mold is only injected onto the first raw mold once the first raw mold has solidified.

[0091] In one embodiment, the process is carried out several times in succession, in particular four times in succession, to obtain a Halbach array which has a plurality of raw forms, in particular five raw forms.

[0092] The invention also includes a raw magnet, in particular a permanent magnet obtained after magnetization of the raw magnet, in particular a Halbach array, 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.

[0093] The invention also includes a raw magnet, in particular a permanent magnet obtained after magnetization of the raw magnet, which has at least one separating layer arranged in the interior of the permanent magnet, preferably as an electrically resistive layer or as an electrically insulating layer. In particular, the permanent magnet is produced in a method according to the invention or in a method according to one or more of the embodiments described above.

[0094] In one embodiment, the permanent magnet has at least five separating layers, preferably at least ten separating layers, preferably at least 15 separating layers, particularly preferably 20 separating layers, in the interior of the permanent magnet, wherein a separating layer is arranged between each pair of layers of the permanent magnet formed from a raw form.

[0095] The invention further includes the use of such a raw magnet, in particular 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.

[0096] 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, wherein the device has a permanent magnet which is created by means of a method according to the invention or a method according to one or more of the embodiments described above.

[0097] The invention will be explained in more detail below with reference to the drawing. The drawing shows: Fig. 1 a flowchart of a first embodiment of a method for producing a raw magnet, Fig. 2 a flowchart of a second embodiment of the method for producing the raw magnet, Fig. 3 a flowchart of a third embodiment of the method for producing the raw magnet, Fig. 4 a schematic representation of a first and second joining process for producing a third raw shape, and Fig. 5 a schematic representation of a third joining process for producing the third raw shape as a Halbach array.

[0098] Figure 1 shows a flowchart of a first embodiment of a method for producing a raw magnet 4.

[0099] In step a), a first raw form 2.1 is produced from a first magnetic starting material 1.1.

[0100] In step b), a second raw form 2.2 is produced from a second magnetic starting material 1.2.

[0101] Particularly preferably, the first magnetic starting material 1.1 and / or the second magnetic starting material 1.2 is a material made from particles of an R x T y B alloy and preferably particles of a rare-earth-rich phase. Alternatively, the first magnetic starting material 1.1 and / or the second magnetic starting material 1.2 is a material selected from the group consisting of an aluminum-nickel-cobalt alloy, a samarium-cobalt alloy, and a ferrite alloy.

[0102] An external magnetic field 21 is applied to at least one raw form 2, selected from a group consisting of the first raw form 2.1 and the second raw form 2.2, during and / or after the production of the raw form 2 according to step a) or b).

[0103] Preferably, the first raw form 2.1 is produced in the externally applied magnetic field 21. Alternatively or additionally, the external magnetic field 21 is applied to the first raw form 2.1 after its production. Alternatively or additionally, the second raw form 2.2 is produced in the externally applied magnetic field 21. Alternatively or additionally, the external magnetic field 21 is applied to the second raw form 2.2 after its production.

[0104] It is particularly preferred that a first external magnetic field is applied to the first raw form 2.1 during and / or after its production. Additionally, a second external magnetic field is applied to the second raw form 2.2 during and / or after its production.

[0105] Preferably, the first raw form 2.1 is produced in the first externally applied magnetic field, and the second raw form 2.2 is produced in the second externally applied magnetic field. Alternatively or additionally, the first external magnetic field is applied to the first raw form 2.1 after its production, and the second external magnetic field is applied to the second raw form 2.2 after its production.

[0106] Preferably, the first raw form 2.1 is produced in the first externally applied magnetic field, and the second external magnetic field is applied to the second raw form 2.2 after its production. Alternatively or additionally, the first external magnetic field is applied to the first raw form 2.1 after its production, and the second raw form 2.2 is produced in the second externally applied magnetic field.

[0107] Preferably, the first external magnetic field and the second external magnetic field differ from each other; in particular, the first external magnetic field and the second external magnetic field are not identical. Preferably, a first particle orientation 7.1 of the first raw shape 2.1 is generated by means of the first magnetic field, and a second particle orientation 7.2 of the second raw shape 2.2 is generated by means of the second magnetic field. Alternatively, instead of using the first magnetic field and the second magnetic field, in particular to generate two different particle orientations 7, the orientation of the first raw shape 2.1 and / or the second raw shape 2.2 is varied in the external magnetic field.

[0108] Preferably, at least one raw form 2, selected from the first raw form 2.1 and the second raw form 2.2, is produced, in particular in step a) and / or in step b), by means of a process selected from a group consisting of injection molding, additive manufacturing, extrusion, cold pressing, dry pressing, and wet pressing.

[0109] In step c), the first raw form 2.1 and the second raw form 2.2 are joined together by joining, producing a third raw form 3.

[0110] The third raw form 3 is preferably produced by means of a method selected from a group consisting of material joining, in particular gluing, form-fitting joining, force-liquid joining, and loose joining.

[0111] In step d), the third raw shape 3 is sintered, yielding the raw magnet 4. Preferably, the third raw shape 3 is sintered in an atmosphere containing at least one process gas selected from the group consisting of argon and helium. Particularly preferably, the atmosphere consists of at least one process gas selected from the group consisting of argon and helium. Alternatively, the third raw shape 3 is sintered in a vacuum.

[0112] Figure 2 shows a flowchart of a second embodiment of a method for producing the raw magnet 4.

[0113] Identical and functionally equivalent elements are provided with the same reference symbols in all figures, so that reference is made to the preceding description in each case.

[0114] Furthermore, identical or functionally equivalent process steps are marked with identical letters, so that reference is made to the preceding description in each case.

[0115] The first magnetic starting material 1.1 is mixed with a first binder 5.1, yielding a first mixture 6.1 of the first magnetic starting material 1.1 and the first binder 5.1. In step a), the first crude form 2.1 is produced from the first mixture 6.1.

[0116] The second magnetic starting material 1.2 is mixed with a second binder 5.2, yielding a second mixture 6.2 consisting of the second magnetic starting material 1.2 and the second binder 5.2. In step b), the second crude form 2.2 is produced from the second mixture 6.2.

[0117] In step c), the first raw form 2.1 and the second raw form 2.2 are joined together by joining, whereby the third raw form 3 is produced.

[0118] In step d0), the first binder 5.1 and the second binder 5.2 are at least partially, preferably completely, removed from the third raw form 3 before sintering and after the production of the third raw form 3.

[0119] Preferably, a first main component of the first binder 5.1 and a second main component of the second binder 5.2 are identical. Alternatively or additionally, the first binder 5.1 and the second binder 5.2 comprise at least one substance selected from the group consisting of polyoxymethylene, polypropylene, paraffin wax, polyethylene, and polyamide.

[0120] Figure 3 shows a flowchart of the embodiment according to the invention of a method for producing the raw magnet 4.

[0121] The first raw form 2.1 and the second raw form 2.2 are not produced separately. In step a), the first raw form 2.1 is produced from the first mixture 6.1 by injection molding. In step b), the first raw form 2.1 is overmolded with the second mixture 6.2 by injection molding. In step b), the second mixture 6.2 is injected onto the first raw form 2.1 by injection molding. Thus, in step b), the second raw form 2.2 is produced, with the second mixture 6.2 forming a positive-locking bond with the first raw form 2.1. In step c), the second raw form 2.2 preferably solidifies and thus shrinks onto the first raw form 2.1 and / or bonds with the first raw form 2.1, producing the third raw form 3. In this embodiment, the joining process step therefore comprises the solidification of the second raw form 2.2. Figure 4 a)shows a schematic representation of a first joining process for producing the third raw form 3.

[0122] The first raw form 2.1 and the second raw form 2.2 are joined together to form the third raw form 3 by means of a form-fitting connection.

[0123] The first raw form 2.1 is produced in a first externally applied magnetic field. Alternatively or additionally, the first external magnetic field is applied to the first raw form 2.1 after its production. Therefore, the first raw form 2.1 exhibits the first particle orientation 7.1.

[0124] The second raw form 2.2 is produced in the first externally applied magnetic field. Alternatively or additionally, the first external magnetic field is applied to the second raw form 2.2 after its production. Therefore, the second raw form 2.2 exhibits the second particle orientation 7.2, which differs from the first particle orientation 7.1.

[0125] Alternatively, the second raw form 2.2 is produced in a second externally applied magnetic field. Alternatively or additionally, the second external magnetic field is applied to the second raw form 2.2 after its production. Therefore, the second raw form 2.2 exhibits the second particle orientation 7.2.

[0126] In particular, the first external magnetic field and the second external magnetic field differ from each other; specifically, the first external magnetic field and the second external magnetic field are not identical. Therefore, the first particle orientation 7.1 and the second particle orientation 7.2 differ from each other; specifically, the first particle orientation 7.1 and the second particle orientation 7.2 are not identical.

[0127] Preferably, the first geometry 9.1 of the first raw form 2.1 and the second geometry 9.2 of the second raw form 2.2 are matched such that the first raw form 2.1 and the second raw form 2.2 can be joined together to form the third raw form 3 by means of a positive-locking connection. Alternatively, the first geometry 9.1 and / or the second geometry 9.2 are machined by means of a machining process such that the first raw form 2.1 and the second raw form 2.2 can be joined together to form the third raw form 3 by means of a positive-locking connection.

[0128] The first geometry 9.1 and the second geometry 9.2 have a tongue-and-groove connection 11.

[0129] Figure 4 b) shows a schematic representation of a second joining process for producing the third raw form 3.

[0130] The first raw form 2.1 and the second raw form 2.2 are joined together to form the third raw form 3 by means of loose joining.

[0131] Preferably, the first raw mold 2.1 has a recess 13 into which the second raw mold 2.2 is inserted. Particularly preferably, the recess 13 of the first raw mold 2.1 is larger than that of the second raw mold 2.2.

[0132] During the sintering of the third raw form 3, the first raw form 2.1 and the second raw form 2.2 shrink. Since the initial volume shrinkage of the first raw form 2.1 during sintering is greater than the subsequent volume shrinkage of the second raw form 2.2, the first raw form 2.1 shrinks onto the second raw form 2.2, and a force-fit connection is formed between the first raw form 2.1 and the second raw form 2.2. Advantageously, a material-bonded connection is also created during sintering between a first contact surface 15.1 of the first raw form 2.1 and a second contact surface 15.2 of the second raw form 2.2.

[0133] Alternatively, a separating layer 17 is inserted between the first connecting surface 15.1 of the first raw form 2.1 and the second connecting surface 15.2 of the second raw form 2.2, thereby preventing a material-bonded connection between the first raw form 2.1 and the second raw form 2.2, in particular between the first connecting surface 15.1 of the first raw form 2.1 and the second connecting surface 15.2 of the second raw form 2.2.

[0134] Preferably, the separating layer 17 is a material comprising at least one compound selected from the group consisting of aluminum oxide, zirconium oxide, yttrium oxide, and at least one rare earth oxide. Particularly preferably, the separating layer 17 comprises at least one compound selected from the group consisting of aluminum oxide, zirconium oxide, yttrium oxide, and at least one rare earth oxide.

[0135] Figure 5shows a schematic representation of a third joining method according to the invention for producing the third raw form 3 as a Halbach array.

[0136] In Figure 5 a) The first raw form 2.1 is produced in the externally applied magnetic field 21. Alternatively, after the first raw form 2.1 has been produced, the external magnetic field 21 is applied to it while the first raw form 2.1 is preferably heated to a softening temperature. During this process, the particles of the first magnetic starting material 1.1 align themselves according to a magnetic field orientation 19 of the external magnetic field 21, and the first particle orientation 7.1 is generated in the first raw form 2.1. The first raw form 2.1 is then rotated such that the first particle orientation 7.1 in the first raw form 2.1 is orthogonal to the magnetic field orientation 19.

[0137] The first raw form 2.1 is produced from the first mixture 6.1 by injection molding.

[0138] In Figure 5 b) The second raw form 2.2 is injection-molded onto the turned first raw form 2.1 using the second mixture 6.2 in the externally applied magnetic field 21, thereby producing the third raw form 3. During this process, the particles of the second magnetic starting material 1.2 align themselves according to the external magnetic field 21, and the second particle orientation 7.2 is generated in the second raw form 2.2.

[0139] From the third raw form 3, a raw magnet 4 in the form of a Halbach array is obtained by means of sintering.

Claims

1. Method for manufacturing a raw magnet (4), wherein - a Halbach-Array is manufactured as the raw magnet (4), wherein - a first raw form (2.1) is manufactured from a first magnetic base material (1.1), wherein - a second raw form (2.2) is manufactured from a second magnetic base material (1.2), wherein - an external magnetic field (21) is applied to at least one raw form (2) selected from a group consisting of the first raw form (2.1) and the second raw form (2.2) during manufacturing of the raw form (2), wherein - the first raw form (2.1) is manufactured by means of injection molding in the externally applied magnetic field (21) comprising a magnetic field orientation (19), wherein - the first raw form (2.1) is subsequently rotated such that a particle orientation (7) in the first raw form (2.1) is orthogonal to the magnetic field orientation (19), wherein - the second raw form (2.2) is injection molded onto the rotated first raw form (2.1) in the externally applied magnetic field (21) by means of injection molding, wherein - a third raw form (3) is manufactured from the first raw form (2.1) and the second raw form (2.2) by joining them together, wherein - the third raw form (3) is sintered, wherein the raw magnet (4) is obtained.

2. Method according to claim 1, wherein as the first magnetic base material (1.1) and / or as the second magnetic base material (1.2) a material is used which is made of particles of an RxTyB alloy and preferably particles of a rare-earth-rich phase.

3. Method according to claim 1, wherein as the first magnetic base material (1.1) and / or as the second magnetic base material (1.2) a material is used which is made of particles selected from a group consisting of an aluminium-nickel-cobalt alloy, a samarium-cobalt alloy, and a ferrite alloy.

4. Method according to any one of the preceding claims, wherein a first external magnetic field is applied to the first raw form (2.1) during and / or after manufacturing of the first raw form (2.1), wherein a second external magnetic field is applied to the second raw form (2.2) during and / or after manufacturing of the second raw form (2.2).

5. Method according to any one of the preceding claims, wherein - the first magnetic base material (1.1) is mixed with a first binder (5.1), wherein - a first mixture (6.1) of the first magnetic base material (1.1) and the first binder (5.1) is obtained, wherein - the first raw form (2.1) is manufactured from the first mixture (6.1), wherein - the second magnetic base material (1.2) is mixed with a second binder (5.2), wherein - a second mixture (6.2) of the second magnetic base material (1.2) and the second binder (5.2) is obtained, wherein - the second raw form (2.2) is manufactured from the second mixture (6.2), wherein - the first binder (5.1) and the second binder (5.2) are at least partially removed from the first raw form (2.1) and / or the second raw form (2.2) after and / or before manufacturing the third raw form (3) and before sintering.

6. Method according to any one of the preceding claims, wherein a first main component of the first binder (5.1) and a second main component of the second binder (5.2) are identical.

7. Method according to any one of the preceding claims, wherein at least one raw form (2) selected from the first raw form (2.1) and the second raw form (2.2) is manufactured by a method selected from a group consisting of injection molding, additive manufacturing, extrusion, cold pressing, dry pressing, and wet pressing.

8. Method according to any one of the preceding claims, wherein the second raw form (2.2) is injection molded onto the first raw form (2.1) by means of injection molding, in particular of the second mixture (6.2), wherein the third raw form (3) is manufactured.

9. Method according to any one of the preceding claims, wherein the third raw form (3) is manufactured by means of a method selected from a group consisting of substance-to-substance bonding, in particular gluing, form bonding, frictional bonding and loose bonding.

10. Method according to any one of the preceding claims, wherein the first binder (5.1) and the second binder (5.2) comprise at least one compound selected from a group consisting of polyoxymethylene, polypropylene, paraffin wax, polyethylene and polyamide.

11. Method according to any one of the preceding claims, wherein a separating layer (17) is arranged between a first connection surface (15.1) of the first raw form (2.1) and a second connection surface (15.2) of the second raw form (2.2).

12. Method according to any one of the preceding claims, wherein as the separating layer (17) a material is used which is made of at least one compound selected from a group consisting of aluminium oxide, zirconium oxide, yttrium oxide, and at least one rare-earth-oxide.

13. Method according to any one of the preceding claims, wherein the third raw form (3) is sintered in a vacuum or in an atmosphere comprising at least one process gas selected from a group consisting of argon and helium.

14. Method according to any one of the preceding claims, wherein an external magnetic field (21) is applied to at least one raw form (2) selected from a group consisting of the first raw form (2.1) and the second raw form (2.2) additionally after manufacturing of the raw form (2).

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