Manufacturing method of raw magnet

Abstract

The present invention relates to a method for producing a raw magnet (1), comprising mixing a magnetic starting material (3) with a binder (5) to obtain a mixture (7) of the magnetic starting material (3) and the binder (5), producing a base form (9) from the mixture (7), treating the base form (9) with a dispersion (11) comprising at least one dispersing medium and a dispersed phase to obtain a treated base form (13), wherein at least one first substance (15) selected from the dispersing medium and the dispersed phase comprises an alloy additive for the raw magnet (1), and sintering the treated base form (13) to obtain the raw magnet (1).

Description

[Technical Field]

[0001] The present invention relates to a method for producing raw magnets (Rohmagnets). [Background technology]

[0002] Permanent magnets made from rare earth elements, produced from raw magnets, are used in many technical applications and are characterized by a particularly high energy product, in particular neodymium-iron-boron magnets, up to 400 kJ / m 3 has an energy product of

[0003] A requirement for permanent magnets, particularly in industrial applications, is that they have as high a coercive force as possible, which is the strength with which a permanent magnet can remain undamaged when exposed to an opposing magnetic field.

[0004] Permanent magnets made from the rare earth group, and in particular neodymium-iron-boron magnets, have a particularly temperature-dependent coercivity, which decreases with increasing temperature. Therefore, in industrial applications, particularly those that may involve high temperatures, and in particular electric motors, permanent magnets with high coercivity are advantageously used.

[0005] One way to increase the coercivity is to alloy with at least one additional rare earth element, in particular at least one "heavy" rare earth element, such as dysprosium and / or terbium. These elements are very expensive and have the disadvantage of reducing the remanence of the permanent magnet.

[0006] A second way to increase the coercivity relative to a comparable permanent magnet is to create a microstructure that is composed of finer particles than the starting powder of the comparable permanent magnet. Such a microstructure can be achieved, in particular, by using a starting powder that is finer than the starting powder of the comparable permanent magnet. Such finer powders, especially those with a particle size of less than 5 μm, have the disadvantage that, on the one hand, they are very difficult to manufacture in terms of process technology, and, on the other hand, they are very difficult to process, especially since the fine powders are prone to oxidation and therefore unusable.

[0007] A third way to increase coercivity is to use appropriate heat treatment, especially for permanent magnets produced by sintering, but the drawback is that the coercivity can only be increased to a very limited extent.

[0008] Furthermore, a grain boundary diffusion method known as grain boundary diffusion can be used. In this case, the sintered original form is coated with a dispersion of active materials immediately after the sintering process, after a grinding or wire cutting process, or after removing surface impurities by a post-treatment process with acid. These active materials contain at least one heavy rare earth element, which diffuses into the permanent magnet along the grain boundaries during a subsequent heat treatment process. The disadvantage is that the diffusion process is slow, so only permanent magnets with a wall thickness of up to 5 mm can be processed economically.

[0009] Furthermore, a powder mixing method called powder blending can be used. In this case, various powders are mixed together to produce a master form for a NdFeB permanent magnet. These powders have, on the one hand, various proportions of heavy rare earth elements and different particle sizes. During sintering of the master form, the heavy rare earth elements are embedded in the grain boundary regions. A disadvantage of this powder blending method is that different powders tend to aggregate due to van der Waals forces and / or magnetic attraction, which can result in demanding mixing and local inhomogeneity. This can make it very difficult to optimally utilize the heavy rare earth elements. Summary of the Invention [Problem to be solved by the invention]

[0010] The problem underlying the present invention is therefore to provide a method for producing raw magnets, in particular permanent magnets, in which the above-mentioned drawbacks, in particular those cited with respect to the permanent magnets produced, are at least partially eliminated, preferably avoided. [Means for solving the problem]

[0011] The above-mentioned problems are solved by providing the present technical teachings, in particular the teachings of the independent claims, as well as the embodiments disclosed in the dependent claims and the specification.

[0012] The above-mentioned problems are solved by providing a method for producing a raw magnet, in particular, by mixing a magnetic starting material with a binder to obtain a mixture of the magnetic starting material and the binder. Subsequently, a base form is produced from this mixture. Furthermore, the base form is treated with a dispersion containing at least one dispersion medium and a dispersed phase to obtain a treated base form. In this case, at least one first substance selected from the dispersion medium and the dispersed phase contains an alloy additive for the raw magnet. The treated base form is then sintered to obtain the raw magnet.

[0013] Advantageously, the method allows for the economical and uniformly distributed introduction of a first material, particularly an alloying additive, into the base form. The economical introduction of the first material, particularly an alloying additive, reduces the cost of the base magnet when the alloying additive is expensive and rare. Furthermore, the magnetic properties of the base magnet, particularly the coercivity, are preferably improved, particularly increased, compared to conventionally produced magnets. Furthermore, the method allows for the processing of base forms having wall thicknesses of up to 40 mm. Advantageously, the first material, particularly the alloying additive, diffuses into the base form between the grains of the magnetic starting material, particularly along the grain boundaries between the grains. Furthermore, advantageously, the first material, particularly the alloying additive, can diffuse into the grains of the magnetic starting material, thereby also improving the coercivity, particularly when the alloying additive is a heavy rare earth element.

[0014] In particular, the dispersion consists of at least one dispersion medium and a dispersed phase.

[0015] In particular, the at least one first substance is an alloying additive. In particular, the at least one first substance consists of an alloying additive.

[0016] The first substance or alloy additive of the dispersion is in particular a rare earth element, in particular a heavy rare earth element, in particular dysprosium, terbium, holmium, and a light rare earth element, in particular praseodymium, neodymium, oxides of rare earth elements, hydrides of rare earth elements, nitrides of rare earth elements, carbides of rare earth elements, halides of rare earth elements, copper-rare earth element compounds, aluminum-rare earth element compounds, zirconium-rare earth element compounds, gallium-rare earth element compounds, R containing heavy rare earth elements. x T y B alloy, dysprosium-cobalt compounds, dysprosium-terbium-cobalt compounds, and terbium-cobalt compounds.

[0017] Advantageously, this method is suitable for powdered magnetic starting materials formed on the basis of freshly melted alloys, in particular in the form of cast blocks or melt-spun materials. Alternatively or additionally, the method is suitable for recycled magnetic materials and / or contaminated recycled magnetic materials. Furthermore, the recycled material is preferably alloyed with at least one rare earth element, preferably in powder form, to improve its properties.

[0018] The magnetic starting material is present in particular in pure or hydrogenated form. US patent application US 2013 / 0263699 A1 and German patent DE 19843883 C1 describe a method called hydrofractionation (HD) for producing hydrogenated forms of magnetic starting materials by hydrogen-induced cracking.

[0019] Preferably, the magnetic starting material is mechanically comminuted, in particular by grinding, to a particle size of 1 μm to 200 μm to obtain a powdered magnetic starting material.

[0020] Preferably, the magnetic starting material is not partially or completely dehydrated after grinding and / or before mixing with the binder, but is present in a hydrated state, in particular the magnetic starting material is mixed with the binder in a hydrated state after grinding.

[0021] In one embodiment of the method, the mixture comprises at least 45% and up to 75% volume fraction of magnetic starting material and at least 25% and up to 55% volume fraction of binder, which preferably comprises at least one organic binder component.

[0022] In one embodiment, the binder comprises at least two, particularly at least three, binder components. In particular, the first of the at least two binder components is a base polymer, which is soluble in the solvent used for preliminary debinding and / or decomposable by the acid used for preliminary debinding. Furthermore, the second of the at least two binder components is a backbone polymer, which is insoluble or very poorly soluble in the solvent used for preliminary debinding and / or not decomposable by the acid used for preliminary debinding. In particular, the backbone polymer has a solubility of less than 1 g / liter in the solvent. Furthermore, the backbone polymer preferably does not swell in the solvent used for preliminary debinding. As a result, the backbone polymer advantageously stabilizes the original form until it is sintered. In particular, the binder comprises a third binder component, which is a further base polymer, a further backbone polymer, and / or a dispersant.

[0023] In particular, the binder comprises at least one material selected from the group consisting of polyoxymethylene, polypropylene, paraffin wax, polyethylene, and polyamide. Preferably, polyoxymethylene, polypropylene, paraffin wax, polyethylene, and polyamide are advantageously thermoplastic resins and therefore suitable for producing master forms. Furthermore, the at least one material selected from the group consisting of polyoxymethylene, polypropylene, paraffin wax, polyethylene, and polyamide facilitates the orientation of the particles of the magnetic starting material.

[0024] In particular, the binder comprises at least one material selected from the group consisting of polyoxymethylene, polypropylene, paraffin wax, polyethylene, and polyamide, and at least one backbone polymer.

[0025] In particular, polyethylene, especially LDPE, is used as at least one backbone polymer. Alternatively or additionally, wax, especially paraffin wax, is used as the base polymer. Alternatively or additionally, a surfactant, especially stearic acid, is used as the dispersant.

[0026] In particular, the preliminary debinding uses at least one non-polar organic solvent selected from the group consisting of n-heptane, n-hexane, and cyclohexane. Alternatively or additionally, the preliminary debinding uses at least one polar organic solvent selected from the group consisting of acetone, isopropanol, and ethanol. Alternatively or additionally, the preliminary debinding uses at least one acid selected from the group consisting of nitric acid, acetic acid, and oxalic acid.

[0027] In one embodiment, the binder comprises polyethylene, particularly LDPE, as a backbone polymer, a wax, particularly paraffin wax, as a base polymer, and a surfactant, particularly stearic acid, as a dispersant. Further, a non-polar organic solvent, particularly n-heptane, is used for the preliminary debinding.

[0028] In particular, a colloidal dispersion is used as the dispersion.

[0029] In particular, stable dispersions are used. In the context of the present technical teachings, stable dispersions are characterized in that the dispersed phase, in particular the alloy additive for the raw magnet, settles very slowly in the Earth's gravitational field, in particular only after at least one hour, or does not settle at all.

[0030] In one embodiment, the original form is treated with the dispersion at least twice, in particular three or more times. Alternatively, the original form is first treated at least once with a first dispersion and then at least once with a second dispersion, the first and second dispersions being different from each other. In particular, the first dispersion comprises a first alloy additive and the second dispersion comprises a second alloy additive, the first and second alloy additives being different from each other. Alternatively or additionally, the treated original form is treated with a further substance, in particular a liquid, in particular before sintering. In particular, the original form is treated with multiple (in particular different) dispersions and / or multiple (in particular different) further substances in multiple treatment steps.

[0031] In particular, preforms with a wall thickness of 0.4 mm up to 10 mm are produced and treated with the dispersion.

[0032] In particular, the raw magnet is magnetized by a magnetic field, in particular a magnetic pulse, to obtain a permanent magnet. Preferably, the magnetic field, in particular the magnetic pulse, has a magnetic flux density of at least 2 Tesla, particularly advantageously at least 3 Tesla. In particular, a method including this step is a method for producing a permanent magnet.

[0033] According to a further embodiment of the present invention, the magnetic starting material is R x T y Preferably, a material containing particles of the R B alloy is used as the magnetic starting material. x T y A material consisting of particles of the B alloy is used. Particularly advantageously, as the magnetic starting material, Nd x Fe y Contains particles of B alloy or Nd x Fe y A material consisting of particles of alloy B is used.

[0034] Preferably, the magnetic starting material is R x T y A material containing particles of the B alloy and particles of a rare earth rich phase is used. In particular, the magnetic starting material is preferably R x T yThe magnetic starting material is preferably a mixture of particles of the B alloy and particles of a rare earth-rich phase. x Fe y A material is used which comprises or consists of particles of the B alloy and particles of a neodymium-rich phase. In particular, the magnetic starting material is advantageously Nd x Fe y It comprises or consists of a mixture of particles of the B alloy and particles of the neodymium-rich phase.

[0035] In the context of the present technical teaching, R represents a rare earth element, 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 are partially or completely substituted for each other so that either only iron, or only cobalt, or an iron-cobalt mixture is present. Preferably, the rare earth element is neodymium. In an advantageous embodiment, R x T y The B alloy further comprises, preferably in trace amounts, additional elements, preferably metals, especially transition metals, selected from the group consisting of aluminum, copper, zirconium, gallium, hafnium, and niobium.

[0036] Preferably, the magnetic starting material is NdFe 14 Contains particles of B alloy or Nd2Fe 14 It consists of particles of B alloy.

[0037] 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 comprises R x T y B alloys, especially Nd x Fe y B alloy. Alternatively or additionally, at least one rare earth element, in particular neodymium, is present in a hydride form. Preferably, the neodymium-rich phase is NdH and / or NdH 2.7 or NdH2 and / or NdH 2.7Alternatively, 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 a chemical compound of this rare earth element, in particular neodymium.

[0038] The rare earth rich phase advantageously forms a phase present along the grain boundaries in the microstructure of the raw magnet, and particularly in the microstructure of the permanent magnet obtained from the raw magnet.

[0039] According to a further embodiment of the invention, an external magnetic field is applied to the master form during its production. Alternatively or additionally, an external magnetic field is applied to the master form after its production. Advantageously, the dipoles of the magnetic starting material are aligned in parallel by the external magnetic field during and / or after the production of the master form.

[0040] Preferably, after applying the magnetic field to the master form, the master form is treated with the dispersion.

[0041] Preferably, the external magnetic field is generated by a switchable electromagnet and / or a permanent magnet.

[0042] In one embodiment, the master form is produced in an external magnetic field. Preferably, during production of the master form, the particles of the magnetic starting material from which the master form is produced are oriented in response to the external magnetic field. Preferably, the magnetic starting material of the master form is hard magnetic. In particular, the external magnetic field is applied to the master form only during production of the master form. In particular, no external magnetic field is applied to the master form after production of the master form.

[0043] In a further embodiment, the external magnetic field is applied to the master form after its production. In particular, the external magnetic field is applied to the master form only after its production. In particular, no external magnetic field is applied to the master form during its production.

[0044] In a further embodiment, an external magnetic field is applied to the prototype during and after its creation.

[0045] Preferably, the master form is heated to the softening temperature of the mixture while applying an external magnetic field.

[0046] According to a further embodiment of the present invention, the master form is preliminarily debound before treatment with the dispersion. Alternatively or additionally, the master form is preliminarily debound during treatment with the dispersion. Alternatively or additionally, the treated master form is debound before sintering. In particular, during the preliminarily debinding, soluble binder components are dissolved from the master form, whereby the master form advantageously has an at least partially open-pored surface, in particular a completely open-pored surface. In particular, a master form porosity of at least 30% by volume, preferably at least 40% by volume, preferably at least 50% by volume, more preferably at least 55% by volume and up to 60% by volume is obtained. Advantageously, the backbone polymer of the binder remains in the master form after the preliminarily debinding. The backbone polymer preferably increases the mechanical stability of the master form.

[0047] The at least partially open-pored surface and / or open-pored structure of the parent form preferably allows the dispersion, particularly the first substance, particularly the alloying additive, to penetrate quickly and uniformly into the parent form, and further advantageously allows the dispersion, particularly the first substance, particularly the alloying additive, to freely diffuse into the parent form during any subsequent heat treatment.

[0048] In particular, the preliminary debinding is carried out as a solvent debinding.

[0049] If the treatment with the dispersion is carried out after preliminary debinding, the original form has an open pore structure and the dispersion can easily reach the pore channels of the original form.

[0050] If preliminary debinding is performed simultaneously with treatment with the dispersion, the soluble organic binder components are removed from the form while the first material, particularly the alloying additive, diffuses into the pore channels of the form.

[0051] In an advantageous embodiment of the method, the binder is at least partially removed from the preform, in particular by means of a solvent, in particular an organic solvent, in particular by solvent extraction, or by further chemical methods. Alternatively or additionally, binder residues are removed from the treated preform by pyrolysis, in particular immediately before sintering. Alternatively, binder residues are removed from the treated preform by pyrolysis during sintering.

[0052] In an alternative embodiment, after treating, and in particular coating, the master form with the dispersion, the master form is preliminarily debindered and / or debound.

[0053] According to a further embodiment of the present invention, the master form is preliminarily debound using a predetermined pressure and a predetermined temperature for a predetermined period of time.

[0054] In particular, the predetermined temperature is at least as high as room temperature, in particular 25° C., in particular the predetermined temperature is at least 30° C. Alternatively or additionally, the predetermined temperature is at most such that the predetermined temperature is at least 10° C. lower than the boiling point of the solvent used during preliminary debinding at the predetermined pressure.

[0055] In particular, the predetermined pressure is at least 50 mbar below atmospheric pressure and up to 50 mbar above atmospheric pressure, preferably the predetermined pressure is approximately the same as atmospheric pressure, in particular the same as atmospheric pressure.

[0056] In particular, the predetermined period of time is at least 1 hour and up to 72 hours.

[0057] According to a further embodiment of the invention, the treated form is dried before sintering.

[0058] In one embodiment, the master form is dried after the first treatment with the dispersion and / or after the treatment with the first dispersion. In particular, after drying the master form, the master form is treated again with the dispersion and / or the second dispersion.

[0059] In a further embodiment, after drying the treated form, the treated form is treated with a further substance.

[0060] According to a further embodiment of the invention, a dispersion suspension or aerosol is used as the dispersion. The second substance of the dispersion, selected from the dispersion medium and the dispersed phase, is in particular selected from the group consisting of solvents, air, nitrogen, argon and helium. The first substance of the dispersion is selected from the group consisting of rare earth elements, in particular heavy rare earth elements, in particular dysprosium, terbium, holmium, and light rare earth elements, in particular praseodymium, neodymium, oxides of rare earth elements, hydrides of rare earth elements, nitrides of rare earth elements, carbides of rare earth elements, halides of rare earth elements, copper-rare earth element compounds, aluminum-rare earth element compounds, zirconium-rare earth element compounds, gallium-rare earth element compounds, R containing heavy rare earth elements. x T y B alloy, dysprosium-cobalt compounds, dysprosium-terbium-cobalt compounds, and terbium-cobalt compounds.

[0061] When a heavy rare earth element is used as an alloy additive, particularly as the first substance, the coercivity is particularly enhanced because the heavy rare earth element accumulates along the grain boundaries during sintering. Alternatively or additionally, the heavy rare earth element diffuses into the grains of the magnetic starting material, which also enhances the coercivity.

[0062] When copper compounds, in particular copper-rare earth compounds, in particular copper-rare earth alloys, or aluminum compounds, in particular aluminum-rare earth compounds, in particular aluminum-rare earth alloys, are used as alloy additives, in particular as the first substance, the layer thickness of the rare earth-rich phase increases, in particular during sintering, and thus the coercivity increases in particular.

[0063] When zirconium compounds, in particular zirconium-rare earth compounds, in particular zirconium-rare earth alloys, are used as alloy additives, in particular as the first substance, grain growth is preferably reduced and / or prevented, in particular during sintering.

[0064] When a gallium compound, in particular a gallium-rare earth compound, in particular a gallium-rare earth alloy, is used as the alloy additive, in particular as the first substance, the rare earth-rich phase has an amorphous structure, in particular after sintering, which preferably increases the coercivity.

[0065] According to a further embodiment of the invention, as solvent a compound selected from the group consisting of cyclohexane, n-hexane, n-heptane, paraffin oil, acetone, isopropanol, ethanol and organic solvents is used.

[0066] In particular, non-polar solvents, especially organic solvents, are used as solvents.

[0067] According to a further embodiment of the invention, the dispersion comprises the first substance as particles having a particle size of at least 0.001 μm and at most 30 μm. Alternatively or additionally, the volume fraction of the first substance in the dispersion is at least 1% and at most 70%.

[0068] In particular, the first substance is present at the start of the method in particulate form having a particle size of at least 0.001 μm and at most 30 μm. Alternatively, the first substance is treated by a milling step, in particular as a substep of the method, to produce particles having a particle size of at least 0.001 μm and at most 30 μm. Preferably, the milling step is carried out by an apparatus selected from the group consisting of a jet mill, a ball mill, and an attritor mill.

[0069] According to a further embodiment of the invention, the blank is treated with the dispersion by a method selected from the group consisting of spraying, in particular spraying with a spray gun, painting, in particular painting with a brush and / or roller, dipping, printing, in particular pad printing and / or screen printing, and slot die coating. Preferably, the blank is, in particular a preliminarily debinding method, whereby the blank, in particular an open-pored blank, is infiltrated with the dispersion.

[0070] In one embodiment, the original form is immersed in the dispersion so that the original form is completely surrounded by the dispersion. In particular, the dispersion comprises an alloying additive and a solvent. In particular, the dispersion consists of an alloying additive and a solvent. In particular, the original form is immersed in the dispersion for a period of at least 1 second and up to 24 hours, and in particular is covered by the dispersion.

[0071] In a further embodiment, the original form is coated with the dispersion, in particular the entire surface of the original form is coated with the dispersion. In particular, the original form is sprayed and / or coated with the dispersion. In particular, the dispersion comprises an alloying additive and at least one gas selected from the group consisting of air and inert gases, in particular nitrogen, argon, and helium. In particular, the dispersion consists of an alloying additive and at least one gas selected from the group consisting of air and inert gases, in particular nitrogen, argon, and helium. In particular, the original form is sprayed with the dispersion for a period of at least 1 second and up to 30 seconds.

[0072] According to a further embodiment of the invention, the master form is produced by a method selected from the group consisting of injection molding, in particular metal powder injection molding, additive manufacturing, extrusion, and wet pressing.

[0073] In one embodiment of the method, the master form is produced by injection molding of a mixture comprising the magnetic starting material and a binder, in particular an organic binder. Alternatively, the master form is produced by injection molding of a mixture consisting of the magnetic starting material and a binder, in particular an organic binder.

[0074] In a further embodiment of the method, the master form is produced by wet pressing of the magnetic starting material. In the wet pressing, an organic solvent, preferably a volatile, non-polar and / or polar organic solvent, is used as a binder. The volatile, non-polar and / or polar organic solvent is selected from the group consisting of alcohols, acyclic alkanes, cyclic alkanes, ketones, and mixtures of volatile organic substances that can be used as solvents. As alcohols, preferably ethanol or isopropanol is used. As cyclic alkanes, preferably cyclohexane is used. As ketones, preferably acetone is used. The mixture of volatile organic substances is preferably selected from the group consisting of mineral oil, white spirit, and ligroin. Furthermore, the master form is preferably dried before sintering.

[0075] According to a further embodiment of the invention, the treated preform is sintered in a vacuum. Alternatively, the treated preform is sintered in an atmosphere comprising at least one process gas selected from the group consisting of argon and helium. Alternatively, the treated preform is sintered in an atmosphere consisting of at least one process gas selected from the group consisting of argon and helium. Preferably, the particles of the magnetic starting material, in particular R, are sintered during sintering. x T y The B particles are alloyed with the alloying additives, which results in increased magnetic properties, particularly coercivity, of the raw magnet.

[0076] In the context of the present technical teachings, a vacuum is defined as a pressure of 1×10 -3 An atmosphere having a pressure below 100 mbar (absolute pressure) is understood.

[0077] In particular, the primitive form is sintered in a helium atmosphere. Alternatively, the primitive form is sintered in an argon atmosphere. Alternatively, the primitive form is sintered in an argon-helium atmosphere. In particular, the atmosphere selected from the group consisting of a helium atmosphere, an argon atmosphere, and an argon-helium atmosphere is at least 1×10 above atmospheric pressure. -3 In the context of the present technical teaching, a helium atmosphere is understood to mean in particular a gas consisting of pure helium and up to 5% by volume of impurities.

[0078] In the context of the present technical teaching, an argon atmosphere is understood to be a gas consisting in particular of pure argon and a maximum of 5% by volume of impurities.

[0079] In the context of the present technical teaching, an argon-helium atmosphere is understood to be a gas consisting in particular of pure argon, pure helium and up to 5% by volume of impurities.

[0080] In particular, the preform is sintered at a sintering temperature of at least 950°C and up to 1200°C, preferably at least 1000°C and up to 1100°C.

[0081] In one embodiment, during sintering, the treated preform is heated from room temperature or the debinding temperature to the sintering temperature at a heating rate of at least 0.1 K / min and at most 10 K / min. During the heating of the treated preform, preferably at least one holding step at a predetermined intermediate temperature is provided; in particular, multiple holding steps at predetermined intermediate temperatures are incorporated, wherein the temperature in at least one holding step is kept constant for a predetermined period of preferably at least 30 minutes and at most 1200 minutes. In particular, the at least one intermediate temperature is at least 450°C and at most 900°C, preferably at least 700°C and at most 800°C. Advantageously, at least one holding step is carried out to remove particles of magnetic starting material, in particular R x T y The B particles are pre-alloyed with alloying additives. In one embodiment of the method, the holding step improves the diffusion of the alloying additives into the interior of the matrix along the grain boundaries or surfaces of the magnetic starting material.

[0082] The present invention also encompasses raw magnets produced by the method according to the invention or by the method according to one or more of the above embodiments, in particular permanent magnets obtained after magnetization of the raw magnets.

[0083] The invention further encompasses the use of such permanent magnets in devices selected from the group consisting of electric motors, speakers, microphones, generators, hard disk drives, and sensors.

[0084] The present invention also encompasses a device selected from the group consisting of an electric motor, a speaker, a microphone, a generator, a hard disk drive, and a sensor comprising a permanent magnet produced by a method according to the present invention or by a method according to one or more of the above embodiments.

[0085] The invention will be explained in more detail below on the basis of the drawings. [Brief explanation of the drawings]

[0086] [Figure 1] 1 is a flow chart of an exemplary embodiment of a method for producing a raw magnet. [Figure 2] 1 is a schematic diagram of an exemplary embodiment for producing a raw magnet. DETAILED DESCRIPTION OF THE INVENTION

[0087] FIG. 1 shows a flow chart of an exemplary embodiment of a method for producing a raw magnet 1.

[0088] In a first step a), the magnetic starting material 3 is mixed with a binder 5 to obtain a mixture 7 of the magnetic starting material 3 and the binder 5 .

[0089] In particular, R as the magnetic starting material 3 x T y Alternatively, a material containing particles of the R alloy may be used as the magnetic starting material 3. x T y Alternatively, the magnetic starting material 3 may be made of Nd. x Fe y Materials containing particles of B alloy, or Nd x Fe y A material consisting of particles of alloy B is used.

[0090] Preferably, the mixture 7 comprises at least 40% and up to 75% volume fraction of the magnetic starting material 3 and at least 25% and up to 55% volume fraction of the binder 5. The binder 5 preferably comprises at least one organic binder component.

[0091] In a second step b), a master form 9 is produced from the mixture 7. In particular, the master form 9 is produced by a method selected from the group consisting of injection molding, in particular metal powder injection molding, additive manufacturing, extrusion, and wet pressing.

[0092] In particular, in a second step b), in particular during the production of the master form 9, an external magnetic field is applied to the master form 9.

[0093] In a third step c), the master form 9 is treated with a dispersion 11 comprising at least one dispersion medium and a dispersed phase to obtain a treated master form 13. Alternatively, in a third step c), the master form 9 is treated with a dispersion 11 consisting of at least one dispersion medium and a dispersed phase to obtain a treated master form 13.

[0094] In this case, at least one first substance 15 selected from the dispersion medium and the dispersed phase contains an alloy additive for raw magnet 1. In particular, at least one first substance 15 selected from the dispersion medium and the dispersed phase consists of an alloy additive.

[0095] In particular, in step c), the master form 9 is treated with the dispersion 11 by a method selected from the group consisting of spraying, in particular spraying with a spray gun, coating, in particular coating with a brush and / or roller, dipping, printing, in particular pad printing and / or screen printing, and slot die coating.

[0096] In particular, colloidal and / or stable dispersions are used as dispersion 11.

[0097] In particular, a suspension or an aerosol is used as the dispersion 11 .

[0098] In particular, the first material 15 of the dispersion 11 may be a rare earth element, in particular a heavy rare earth element, in particular dysprosium, terbium, holmium, and a light rare earth element, in particular praseodymium, neodymium, oxides of rare earth elements, hydrides of rare earth elements, nitrides of rare earth elements, carbides of rare earth elements, halides of rare earth elements, copper-rare earth element compounds, aluminum-rare earth element compounds, zirconium-rare earth element compounds, gallium-rare earth element compounds, R containing heavy rare earth elements. x T y B alloy, dysprosium-cobalt compound, dysprosium-terbium-cobalt compound, and terbium-cobalt compound. Alternatively or additionally, dispersion 11 comprises first substance 15 as particles having a particle size of at least 0.001 μm and at most 30 μm. Alternatively or additionally, the volume fraction of first substance 15 in dispersion 11 is at least 1% and at most 70%.

[0099] In particular, the second substance 17 of the dispersion 11, selected from the dispersion medium and dispersed phase, is selected from the group consisting of solvents, air, nitrogen, argon, and helium. In particular, as solvents, compounds selected from the group consisting of cyclohexane, n-hexane, n-heptane, paraffin oil, acetone, isopropanol, ethanol, and organic solvents are used.

[0100] In particular, in the third step c), the master form 9 is preliminarily debound, in particular during treatment with the dispersion 11. In particular, the master form 9 is preliminarily debound for a predetermined period of time using a predetermined pressure and a predetermined temperature.

[0101] Optionally, the third step c) is carried out at least twice, in particular several times, so that the original form 9 is treated at least twice, in particular several times, with a dispersion 11 and / or with dispersions 11 that are different from one another, in particular a first dispersion and a second dispersion, in particular, the first dispersion comprising a first first substance and the second dispersion comprising a second first substance, the first first substance and the second first substance being different from one another.

[0102] In a fourth step d), the treated primitive form 13 is sintered to obtain the raw magnet 1. In particular, the treated primitive form 13 is sintered in a vacuum. Alternatively, the treated primitive form 13 is sintered in an atmosphere containing at least one process gas selected from the group consisting of argon and helium.

[0103] In an optional manufacturing step carried out after the fourth step d), the raw magnet is magnetized by a magnetic field, in particular a magnetic pulse, to obtain a magnetized permanent magnet. Preferably, the magnetic field, in particular the magnetic pulse, has a magnetic flux density of at least 2 Tesla, particularly advantageously at least 3 Tesla.

[0104] In an optional fifth step e), an external magnetic field is applied to the master form 9 after the second step b), in particular after production of the master form 9, and before the third step c), in particular before treatment of the master form 9 with the dispersion 11.

[0105] In an optional first sixth step f1), the master form 9 is preliminarily debound after the second step b), in particular after production of the master form 9, and before the third step c), in particular before treatment with the dispersion 11.

[0106] Preferably, the first sixth step f1) is carried out after the fifth step e), but it is also possible to carry out the first sixth step f1) before or simultaneously with the fifth step e).

[0107] In an optional second sixth step f2), the treated form 13 is debindered, in particular thermally debindered, before the fourth step d), in particular before sintering.

[0108] In an optional first seventh step g1), the treated form 13 is dried before the fourth step d), in particular before sintering.

[0109] In an optional second seventh step g2), the treated original form 13 is dried before a new third step c), in particular before a new treatment with dispersion 11 and / or a treatment with a further dispersion 11.

[0110] FIG. 2 shows a schematic diagram of an exemplary method for producing the raw magnet 1.

[0111] In all figures, identical and functionally identical elements are given the same reference numerals and, in that respect, reference is made to the respective preceding description.

[0112] In FIG. 2a), preferably R x T y B alloys, especially Nd x Fe y Shown is a mixture 7 of a magnetic starting material 3 from alloy B and a binder 5, in particular an organic binder. Mixture 7 is used to produce a master form 9, preferably by a method selected from the group consisting of injection molding, additive manufacturing, extrusion, and wet pressing.

[0113] In FIG. 2b) the parent form 9 is shown after preliminary debinding, in particular after at least partial removal of the organic binder 5. In particular, during the preliminary debinding, the soluble binder components of the binder 5 are dissolved out of the parent form 9, so that the parent form 9 has an at least partially open-pored surface, in particular is completely open-pored. In particular, after the preliminary debinding, the backbone polymer 19 of the binder 5 remains in the parent form 9.

[0114] For greater clarity, only one particle of the magnetic starting material 3 is labeled.

[0115] In figure 2c) the original form 9 is represented during treatment with the dispersion 11. In particular, the original form 9 in figure 2c) is infiltrated with the dispersion 11, so that the dispersion 11 penetrates into the pores of the original form 9.

[0116] For a clearer representation, only one particle of magnetic starting material 3 and one backbone polymer 19 are labeled respectively.

[0117] In Figure 2d) the treated precursor 13 is shown, in particular the treated precursor 13 after drying. The first substance 15 is embedded in particulate form between the particles of the magnetic starting material 3 and the backbone polymer 19.

[0118] In FIG. 2e) the raw magnet 1 is shown after sintering. The particles of the magnetic starting material 3 are aggregated into crystal grains 21, especially R x T y B crystal grains are formed. Each crystal grain 21 is surrounded by the first substance 15.

Claims

1. A method for producing a raw material magnet (1), comprising the steps of: - mixing a magnetic starting material (3) with a binder (5) to obtain a mixture (7) of said magnetic starting material (3) and said binder (5), - producing a base form (9) from said mixture (7), - treating the base form (9) with a dispersion (11) comprising at least one dispersion medium and a dispersed phase to obtain a treated base form (13), wherein at least one first substance (15) selected from the dispersion medium and the dispersed phase comprises an alloying additive for the base magnet (1); - sintering the treated base form (13) to obtain the raw magnet (1).

2. As the magnetic starting material (3), R x T y 2. The method according to claim 1, wherein a material is used comprising particles of the B alloy and preferably particles of a rare earth rich phase.

3. 3. The method according to claim 1 or 2, wherein an external magnetic field is applied to the master form (9) during and / or after its manufacture.

4. - the master form (9) is preliminarily debound before and / or during the treatment with the dispersion (11), and / or 4. The method according to any one of claims 1 to 3, wherein the treated form (13) is debindered before sintering.

5. 5. The method according to any one of claims 1 to 4, wherein the master form (9) is preliminarily debound for a predetermined period of time, at a predetermined pressure and at a predetermined temperature.

6. 6. The method according to any one of claims 1 to 5, wherein the treated form (13) is dried before sintering.

7. - a suspension or an aerosol is used as the dispersion (11), - the second substance (17) of the dispersion (11) selected from the dispersion medium and the dispersed phase is selected from the group consisting of a solvent, air, nitrogen, argon, and helium; the first material (15) is a rare earth element, in particular a heavy rare earth element, in particular dysprosium, terbium, holmium, and a light rare earth element, in particular praseodymium, neodymium, oxides of rare earth elements, hydrides of rare earth elements, nitrides of rare earth elements, carbides of rare earth elements, halides of rare earth elements, copper-rare earth element compounds, aluminum-rare earth element compounds, zirconium-rare earth element compounds, gallium-rare earth element compounds, R containing heavy rare earth elements; x T y 7. The method of claim 1, wherein the metal is selected from the group consisting of B alloys, dysprosium-cobalt compounds, dysprosium-terbium-cobalt compounds, and terbium-cobalt compounds.

8. 8. The method according to claim 1, wherein the solvent used is a compound selected from the group consisting of cyclohexane, n-hexane, n-heptane, paraffin oil, acetone, isopropanol, ethanol, and organic solvents.

9. - the dispersion (11) comprises the first substance (15) as particles having a particle size of at least 0.001 μm and at most 30 μm, and / or 9. The method according to any one of claims 1 to 8, wherein the volume fraction of said first substance (15) in said dispersion (11) is at least 1% and up to 70%.

10. 10. The method according to any one of claims 1 to 9, wherein the blank (9) is treated with the dispersion (11) by a method selected from the group consisting of spraying, in particular spraying with a spray gun, coating, in particular coating with a brush and / or roller, dipping, printing, in particular pad printing and / or screen printing, and slot die coating.

11. 11. The method according to any one of claims 1 to 10, wherein the master form (9) is produced by a method selected from the group consisting of injection molding, additive manufacturing, extrusion, and wet pressing.

12. 12. The method according to any one of claims 1 to 11, wherein the treated form (13) is sintered in a vacuum or in an atmosphere comprising at least one process gas selected from the group consisting of argon and helium.

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