EP3414768B1 - Hybrid magnet and method for the production thereof - Google Patents

Description

The invention relates to a hybrid magnet which comprises at least one soft magnetic and at least one hard magnetic material. Furthermore, the invention relates to a manufacturing method of such a hybrid magnet.

Magnetic materials can be produced using a melt metallurgical process (as cast magnetic materials) or a powder metallurgical process (as sintered magnetic materials or powder magnetic composite materials). Powder-metallurgical processes that include sintering can be used to produce magnetic components whose shape cannot be achieved by melt metallurgy. This applies e.g. B. especially for magnetic materials with crystal anisotropy (NdFeB, SmCo, etc.). Powder metallurgical manufacturing processes can include the following process steps: powdering a magnetic starting material, pressing the resulting powder into a green part to form a desired shape, sintering the green part, optional thermal treatment to reduce stress and optimize the structure, and optionally magnetization in an external magnetic field. Furthermore, magnets produced in this way can be mechanically post-treated if necessary, for example by grinding or polishing.

A distinction is made in particular between metallic crystalline, metallic amorphous and oxidic materials. Furthermore, magnetic materials are divided according to the size of their coercive field strength (often abbreviated as HcJ) into magnetically hard (having a large coercive field strength), semi-hard (having a medium coercive field strength) and soft (having a small coercive field strength) material types.

So-called hybrid magnets are also known. A hybrid magnet is understood to mean a component which comprises at least two different magnetic materials, in particular at least one hard magnetic material and at least one soft magnetic material. In particular, hybrid magnets are known in which the hard magnetic and the soft magnetic material are integrated in a matrix body made of plastic. Hybrid magnets of this type can have the disadvantage that their magnetic properties are less pronounced than desired, that the temperature stability and mechanical strength can be limited due to the plastic material, and / or that such hybrid magnets cannot be exposed to media that could attack the plastic material.

In the US 6,972,046 B2 discloses a method for manufacturing hybrid magnets. A coating of powder particles is used to avoid the formation of agglomerates.

In the US 2014/0072470 A1 describes a method for producing hybrid magnets, in which a powder mixture is molded with a press die with an angled channel.

WO 2012/159096 A2 envelops hard magnetic with soft magnetic materials and influences the exchange interaction through non-magnetic materials along the grain boundaries.

Proceeding from this, it is an object of the present invention to solve or at least alleviate the technical problems described in connection with the prior art. In particular, a hybrid magnet with improved magnetic, mechanical and / or thermal properties is to be presented. Furthermore, a suitable process for its production is to be specified.

These objects are achieved with a hybrid magnet and a method for producing a hybrid magnet in accordance with the features of the independent claims. Further advantageous refinements of the hybrid magnet and the method are specified in the dependent patent claims. The features listed individually in the claims can be combined with one another in any technologically meaningful manner and can be explained by

Issues from the description are supplemented, further embodiment variants of the invention being shown.

1. A) Erzeugen einer hartmagnetischen Schicht aus einem hartmagnetischen Material,
2. B) Erzeugen einer weichmagnetischen Schicht aus einem weichmagnetischen Material, und
3. C) Erzeugen einer Trennschicht aus einem magnetisch passiven Material, wobei durch jeweils mehrfaches Anwenden der Verfahrensschritte A), B) und C) ein Hybridmagnet geformt wird, der einen Schichtaufbau aufweist.

A process for producing a hybrid magnet contributes to this, comprising at least the following process steps:

1. A) producing a hard magnetic layer from a hard magnetic material,
2. B) producing a soft magnetic layer from a soft magnetic material, and
3. C) Generating a separating layer from a magnetically passive material, a hybrid magnet having a layer structure being formed by repeatedly using method steps A), B) and C).

According to the invention, process step C) is carried out once after each process step A) and once after each process step B). This creates a (single) separating layer between two adjacent layers of hard magnetic material and / or soft magnetic material. Hybrid magnets with a layer structure can be produced, in which the hard magnetic layers and the soft magnetic layers are combined in any layer sequence. Hard magnetic layers and soft magnetic layers are preferably formed alternately or in another regular manner.

Many soft magnetic materials have a higher saturation magnetization than hard magnetic materials. In contrast, a larger coercive field strength is required for hard magnetic materials in order to remagnetize it (reversing the direction of the magnetization). These advantages can be combined with a hybrid magnet, ie a hybrid magnet can have a pronounced effect as a permanent magnet (large remanent magnetization), which can only be destroyed with great difficulty by external influences (large coercive field strength).

The layer structure of the hybrid magnet, in particular when the magnetization is oriented perpendicular to the layer structure, means that the soft magnetic layers are always in a supporting field of the hard magnetic layers and thus contribute to the overall magnetization of the hybrid magnet. If soft magnetic areas are arranged next to hard magnetic areas, e.g. in the extreme case that the hard magnetic layers are magnetized along their layer plane, the soft magnetic layers act as a magnetic short circuit and the hybrid magnet cannot produce a magnetic flux that can be used outdoors.

A hard magnetic layer is to be understood as an area of the hybrid magnet that consists predominantly or exclusively of a hard magnetic material. A hard magnetic layer does not necessarily have to be a coherent area of hard magnetic material. In the case of hybrid magnets with a matrix body in particular, a hard magnetic layer can be formed from partial regions of hard magnetic material which are (partially) separated from one another in the layer plane by the matrix material. Preferably, but not necessarily, all hard magnetic layers consist of the same hard magnetic material. Alternatively, different hard magnetic materials can be used in a hybrid magnet. Different hard magnetic materials can be processed in one layer. However, differently constructed layers can also be present, each consisting of different hard magnetic materials.

Preferred hard magnetic materials are: martensitic steels; Alloys based on CuNiFe [copper, nickel, iron], CuNiCo [copper, nickel, cobalt], FeCoVCr [iron, cobalt, vanadium, chromium], MnAlC [manganese, aluminum, carbon], or AINiCo [aluminum, nickel, cobalt ]; Hard magnets based from PtCo [platinum, cobalt]; Rare earth magnets such as B. NdFeB [neodymium, iron, boron], SmCo [samarium, cobalt], or SmFeN [samarium, iron, nitrogen]; oxidic permanent magnets (hard ferrites); or new types of hard magnets such as B. MnBi [manganese, bismuth] or Fe ₁₆ N ₂ [iron, nitrogen].

A soft magnetic layer is to be understood as an area of the hybrid magnet that consists predominantly or exclusively of a soft magnetic material. A soft magnetic layer does not necessarily have to be a coherent area of soft magnetic material. In particular in the case of hybrid magnets with a matrix body, a soft magnetic layer can be formed from subregions of soft magnetic material which are (partially) separated from one another in the layer plane by the matrix material. Preferably, but not necessarily, all soft magnetic layers consist of the same soft magnetic material. Alternatively, different soft magnetic materials can be used in a hybrid magnet. Different soft magnetic materials can be processed in one layer. However, differently constructed layers can also be present, each consisting of different soft magnetic materials.

Preferred soft magnetic materials are: soft iron, carbon steels, alloys based on FeAl [iron, aluminum], FeAlSi [iron, aluminum, silicon], FeNi [iron, nickel], FeCo [iron, cobalt]; amorphous soft magnetic materials such as B. FeNiBSi [iron, nickel, boron, silicon], FeBSi [iron, boron, silicon]; soft magnetic ferrite materials such as B. MnZn ferrites [manganese, zinc], MgZn ferrites [magnesium, zinc]; Spinel materials such as B. MnMgZn [manganese, magnesium, zinc], NiZn [nickel, zinc]; or garnet materials such as B. BiCa [bismuth, calcium], YGd [yttrium, gadollinium].

In addition or as an alternative to the hard magnetic material and / or the soft magnetic material, a magnetically semi-hard material can be used. If a magnetically semi-hard material is used, the explanations for the hard magnetic materials or the soft magnetic materials apply in an analogous manner. Preferred magnetic semi-hard materials are: alloys based on FeNi [iron, nickel], FeMn [iron, manganese], FeNiMn [iron, nickel, manganese], CoFe [cobalt, iron], or FeCu [iron, copper]; Co ₄₉ Fe ₄₈ V ₃ [cobalt, iron, vanadium; also known as Remendur]; Co ₅₅ NiFe [cobalt, nickel, iron; also known as Vacozet], and Kovar.

The magnetically passive material can in particular be a diamagnetic material or a paramagnetic material. For example, a paramagnetic or diamagnetic metal can be used, such as Dy [dysprosium], Tb [terbium], Al [aluminum], Pt [platinum], Ti [titanium], Cu [copper], Pb [lead], Zn [zinc ], Sn [tin], Ga [gallium], Ge [germanium], Au [gold], Ag [silver], Mg [magnesium], Mo [molybdenum], Mn [manganese], Zr [zirconium], Li [lithium ]. Alloys or oxides of the specified materials can also be used. Further preferred materials are listed below. Preferably, but not necessarily, the same magnetically passive material is used for all separation layers.

An electrically non-conductive or poorly conductive magnetically passive material is preferably used.

In a large electrical conductor, a changing magnetic field can generate electrical currents (eddy currents) due to electromagnetic induction. These can lead to heating of the extended electrical conductor and / or adversely affect its magnetic properties. If separation layers made of an electrically non-conductive or poorly conductive material interrupt the electrical conductivity of the hybrid magnet, eddy currents can be reduced and / or locally restricted.

Eddy currents can be effectively suppressed, in particular in hybrid magnets, with a matrix body, since in them the individual magnetic layers are formed from partial areas of magnetic material which are (partially) separated from one another by the matrix material in the layer plane.

In one embodiment of the process, a coating technology is used in at least one of process steps A), B) and C).

The coating technology is preferably a wet technique, such as. B. a sol-gel process, a dry deposition process, and / or a chemical or physical vapor deposition process. A physical vapor deposition process (PVD) is understood to mean a vacuum-based coating process in which a starting material is converted into the gas phase and deposited on a substrate to be coated. Chemical vapor deposition (CVD) methods are similar to physical vapor deposition methods, with the difference that a chemical reaction takes place here when the starting material is deposited on the substrate. In particular, the coating technologies have in common that the material is supplied in small particles to the substrate and can be connected to the substrate there in such a way that a surface layer is firmly connected to the substrate.

A coating technology (ie in particular a coating method of the above type) is preferably used in each of method steps A), B) and C). In particular, the same coating technology is used for all process steps.

Design of the manufacturing method according to the invention: Method step A) comprises at least the following sub-step:
A1) Providing a hard magnetic powder comprising hard magnetic particles from the hard magnetic material.

Method step B) comprises at least the following sub-step:
B1) Providing a soft magnetic powder comprising soft magnetic particles from the soft magnetic material.

Method step C) comprises at least the following sub-step:
C1) coating at least one of the hard magnetic particles or the soft magnetic particles with at least one coating made of the magnetically passive material.

• D) Formen eines den Hybridmagneten bildenden Körpers gemäß den Verfahrensschritten A), B) und C); und
• E) Sintern des Körpers, wobei eine Temperatur verwendet wird, die hinreichend groß ist, um die Beschichtung in einen die hartmagnetischen Partikel und die weichmagnetischen Partikel umgebenden Matrixkörper umzuformen,

wobei während des gesamten Verfahrens eine Sintertemperatur für das hartmagnetische Material und eine Sintertemperatur für das weichmagnetische Material nicht überschritten werden, und wobei in Verfahrensschritt E) eine Sintertemperatur des magnetisch passiven Materials überschritten wird.The method further preferably comprises the following method steps:

• D) forming a body forming the hybrid magnet in accordance with process steps A), B) and C); and
• E) sintering the body, using a temperature which is sufficiently high to convert the coating into a matrix body surrounding the hard magnetic particles and the soft magnetic particles,

wherein a sintering temperature for the hard magnetic material and a sintering temperature for the soft magnetic material are not exceeded during the entire process, and wherein in process step E) a sintering temperature of the magnetically passive material is exceeded.

The shaping of the hybrid magnet in method step D) can optionally take place in an external magnetic field.

Process steps D) and E) are preferably carried out in the order given. Sub-step A1) can include formulation preparation, mixing and / or portioning of the hard magnetic material used. Furthermore, a powder of the hard magnetic material can be produced in sub-step A1) be, e.g. B. by crushing a solid made of this hard magnetic material.

The above explanations for sub-step A1) can also be used for the provision of the soft magnetic material in sub-step B1).

In sub-step C1), the coating of the particles is preferably carried out using one of the following coating processes: B. "vacuum deposition", "plasma deposition", "sputtering", "molecular beam epitaxy (MBE)", "vapor phase epitaxy", or "liquid phase epitaxy"; CVD such as B. "sol-gel deposition", or "metallo-organic chemical vapor deposition (MOCVD)". These methods are well known to those skilled in the art. In sub-step C1), a single coating layer is preferably applied to the particles. In an alternative embodiment of the method, two coating layers made of different materials are preferably applied in sub-step C1).

The coating of the particles can prevent neighboring particles from agglomerating. This can make the manufacturing process easier. Furthermore, the coating of the particles can reduce a magnetic exchange interaction of neighboring particles, in particular neighboring particles of different materials. The coating of the particles can likewise lead to passivation of the surfaces of the particles. This can reduce the risk of self-ignition of the particles when in contact with air. This can make it easier to carry out the method because an inert gas atmosphere can be dispensed with. In particular, eddy currents can be reduced and / or locally restricted by the electrically insulating coating of the particles.

In process step D), the body is shaped in that the soft magnetic powder and the hard magnetic powder are applied one above the other in the desired order of the layer structure. Optionally, after the application of a layer by wiping the distribution of the powder forming this layer can be improved. The separating layers are formed by coating the particles, so that only layers of the hard magnetic powder and layers of the soft magnetic powder have to be layered one above the other, with exactly one (uniform and / or coherent) separating layer being formed between adjacent layers. In particular, this means that each time step A) is carried out and step B) is carried out, step C) is also carried out.

In process step E), a hybrid magnet is formed from the body formed in process step D) by sintering. Sintering means that the body is exposed to an elevated temperature, the coating of the particles being formed into a matrix body surrounding the particles. The temperature selected for sintering is preferably selected such that the hard magnetic and soft magnetic materials do not sinter. This means in particular that the temperature selected for sintering preferably corresponds at most to the melting temperature of the magnetically passive material or, if such a melting temperature is not well-defined for the material in question, to the transformation temperature. The latter relates to such amorphous materials, such as. B. glass in which a melt does not occur at a certain melting temperature. Instead, the mechanical properties of these materials change continuously over a temperature range. This is characterized by the specification of a transformation temperature. The temperature used for sintering is preferably selected depending on all materials used. For example, the transformation temperature of many glasses is in the range up to 900 ° C. If such a glass is used as a magnetically passive material, a preferred temperature range for the sintering (material-specific) is 400 ° C. to 800 ° C. at normal pressure (1013 hPa), in particular 550 ° C. to 650 ° C. Before step E) the body commonly referred to as pellet. After the sintering has been carried out in step E), the body is usually referred to as sintering.

The entire process, including all process steps, is preferably carried out under conditions in which no (significant or widespread) sintering of the hard magnetic or soft magnetic material used occurs. It should be taken into account that the sintering temperature of a material can be pressure-dependent. The temperature is preferably significantly lower during the entire process, in particular at least 50 ° C. lower and preferably at least 100 ° C. lower than the sintering temperature of each hard magnetic or soft magnetic material used.

In a further embodiment of the method, the coating has a coating thickness which is in the range from 1 nm to 300 nm, in particular in the range from 2 nm to 50 nm. The coating thickness is usually to be understood as the spatial extent of the coating, which is the smallest Dimension. By selecting the layer thickness in the proposed range, the described advantages of the coating can be achieved to a sufficient extent. On the other hand, the layer thickness is small enough not to significantly reduce the magnetic properties of the hybrid magnet.

In a further embodiment of the method, the body is pressed between method steps D) and E) to form an intermediate product, a so-called compact. After the layer structure has been built up from powder by applying the desired layer or layers, an increased pressure applied from the outside can lead to a compression of the particles. This can improve the sintering activity and thus increase the stability of the finished sintered hybrid magnet. A compact is to be understood here as a body which is produced by pressing powder, it being possible in particular to use a die press.

In a further embodiment of the method, the pressing takes place in an external magnetic field.

The external magnetic field can be generated, for example, by an electrical coil. The external magnetic field preferably has an extent which surrounds the entire compact. The external magnetic field is likewise preferably a homogeneous magnetic field which points in the direction of the magnetization desired for the hybrid magnet. The method is particularly preferred if the external magnetic field is oriented perpendicular to the layer plane. The external magnetic field can cause the magnetization of the magnetic particles to align along the external magnetic field. Depending on the materials used, the external magnetic field applied during pressing can advantageously influence the properties of the hybrid magnet. In particular in the case of magnetic materials with a pronounced crystal anisotropy, an external magnetic field applied during the pressing can align the particles in such a way that a preferred direction of magnetization is the same for all particles. After pressing, the alignment of the particles can be fixed. Even if the magnetization is lost again in a later process step (in particular due to the effect of temperature), the alignment of the particles can remain. In the case of a subsequent magnetization, this can be used to benefit from the preferred direction of magnetization common to all particles.

In a further embodiment of the method, the hard magnetic particles and the soft magnetic particles are acted on at least temporarily with ultrasound. Exposure to ultrasound can increase the packing density of the powder. This can improve the stability of the hybrid magnet. The ultrasound is preferably generated by an ultrasound probe in the vicinity of the hybrid magnet. The action with ultrasound preferably takes place before and / or during the pressing.

In a further embodiment of the method, the separating layer has a separating layer thickness which is in the range from 1 nm to 300 nm, in particular in the range from 2 nm to 50 nm. The separating layer thickness is to be understood as the spatial dimension which has the smallest dimension, this also regularly relates to the expansion of the separating layer perpendicular to the layer structure. If the hybrid magnet is made from powder, the separating layer thickness depends in particular on the coating thickness described above. In any case, i. H. For hybrid magnets that are produced in a different way, the advantages described above in connection with the choice of the coating thickness apply in a corresponding manner to the choice of the separating layer thickness.

In a further embodiment of the method, the hybrid magnet is magnetized in an external magnetic field.

The magnetization is preferably carried out when the hybrid magnet has already been sintered.

The method is particularly preferred if the external magnetic field is oriented perpendicular to the layer plane.

After sintering or after finishing, the magnetization can optionally be carried out. The magnetization can in a z. B. generated by an electrical coil, external magnetic field, which is preferably homogeneous and encloses the entire hybrid magnet. This external magnetic field can differ from the external magnetic field described above both in orientation and in strength. The external magnetic field could also be referred to here as a second external magnetic field in order to distinguish it from the magnetic field described above. The external magnetic field used here is preferably sufficiently strong to be parallel To achieve alignment of the magnetization of the particles, which remains even without an external magnetic field (remanent magnetization).

Furthermore, the method can include an (additional) thermal treatment in a further external magnetic field (material-specific, e.g. for Alnico alloys.

A further aspect of the invention relates to a hybrid magnet, comprising a layer structure composed of layers, at least one of the layers being a hard magnetic layer and at least one of the layers being a soft magnetic layer, and adjacent layers being separated by a magnetically passive material.

Such a hybrid magnet is preferably, but not necessarily, produced using the method proposed here. In any case, the explanations described in connection with the method can be used individually or in combination for explanations of the structure, the properties and the advantages of the proposed hybrid magnet.

In a further embodiment of the hybrid magnet, each hard magnetic layer is formed from hard magnetic particles and each soft magnetic layer from soft magnetic particles, the hard magnetic particles and the soft magnetic particles being surrounded by a matrix body. Such a hybrid magnet is preferably produced by the method according to the invention in an embodiment which comprises the use of powder. In this case, the particles in the hybrid magnet correspond to the particles of the powder.

In a further embodiment of the hybrid magnet, the hard magnetic particles and the soft magnetic particles have an (average) diameter (or a grain size) in the range from 0.2 μm to 250 μm.

In a further embodiment of the hybrid magnet, the magnetically passive material forming the matrix body is one of the following materials in particular: glass, glass-ceramic, metallic glass or ceramic.

The execution of the matrix body with one of these materials can be achieved, for example, by sintering a body formed from powder with a corresponding coating. Glasses are understood to mean, in particular, amorphous substances which are structurally present as an irregular structure (network). In contrast, there are in particular crystalline substances that are present in an ordered lattice structure. Metallic glasses are primarily understood to mean metal alloys which, unlike ordinary metals or metal alloys, are amorphous, i. H. have no ordered lattice structure. Glasses, glass ceramics or ceramics are characterized by a particularly high level of corrosion protection and protection against ignition.

In a further embodiment of the hybrid magnet, each layer has a layer thickness and a (spatial) width, the width corresponding to at least ten times the layer thickness for each layer.

The layer thickness is regularly to be understood as the extent of a layer perpendicular to the layer structure. The width is then the extent of the layer perpendicular to the direction in which the layer thickness is measured. This means in particular that with a layer of any shape in any direction perpendicular to the layer structure, the width must be greater than ten times the layer thickness.

There is always a tendency at the side edges of a hard magnetic layer that the magnetic field lines want to short-circuit in the shortest way. This effect is intensified if soft magnetic material is also present in this area. This proportion of short-circuited magnetic field lines is no longer available for the actual task of a permanent magnet, namely to generate a magnetic field in its external space. The requirement that the spatial width of the magnetic layers must be at least 10 times the thickness of the individual layers can minimize the influence of the magnetic short circuits at the edges of the layers.

In a further embodiment of the hybrid magnet, the layers are aligned perpendicular to the magnetization of the hybrid magnet.

As described above, the alignment of the magnetization perpendicular to the layer structure means that the soft magnetic layers are always in a supporting field of the hard magnetic layers and thus contribute to the overall magnetization of the hybrid magnet. With a hybrid magnet with a magnetization aligned perpendicular to the layer structure, the described advantages of a hybrid magnet with a layer structure can be used to the maximum.

The particular advantages and design features presented for the hybrid magnet described can be applied and transferred to the described method in any technologically meaningful manner.

In the following, specific embodiments of the hybrid magnet and / or the manufacturing method for manufacturing the hybrid magnet will be described by way of example.

In a first embodiment of a manufacturing process, starting materials for the manufacturing process are selected and made available in a recipe manufacturing according to component and material requirements (in particular with regard to magnetic properties such as e.g. retentive magnetization and a coercive field strength as well as with regard to temperature properties such as a transformation temperature) . Then prepare in a powder the raw materials pulverized. This happens e.g. B. with conventional techniques. In a subsequent coating, powder particles are coated, e.g. B. with a single or multiple coating. Furthermore, a green compact is built up layer by layer in a layer structure made of powder. Optionally, pressing (with or without a magnetic field) follows to a compact. This is followed by a sintering of the green body, an optional annealing, an optional post-treatment and optionally a magnetization. Three examples of this first embodiment of the manufacturing method are described below.

In a second embodiment of a manufacturing process, the previously described formulation manufacturing is carried out first. This is followed by building up a layer structure and producing layers using coating technologies, which can optionally be carried out in a magnetic field. Finally, as before, sintering, optional tempering, optional post-treatment and optional magnetization follow. Two examples of this second embodiment of the manufacturing method are described below.

A first example of a hybrid magnet relates to a hybrid magnet made of powder, consisting of NdFeB [neodymium, iron, boron] as a hard magnetic material. 90% of the particles of this material have a diameter of less than 3 µm, 50% of less than 1 µm and 30% of 0.2 to 0.5 µm. Furthermore, the hybrid magnet consists of pure iron [Fe] as a soft magnetic material. 90% of the particles of this material have a diameter of less than 2 µm and 30% of 0.2 to 0.8 µm. The coating is formed from an oxide composition comprising the following proportions: 30 to 60 mol% Bi ₂ O ₃ [bismuth oxide], 30 to 40 mol% B ₂ O ₃ [boron oxide], 10 to 20 mol% ZnO [zinc oxide] and 5 to 10 mol% SiO ₂ [silicon dioxide]. The layer structure alternately has a hard magnetic and a soft magnetic layer, with adjacent layers being separated from each other by a separating layer (indirectly by coating the Powder). The body is 100 mm by 300 mm wide and has a height of 8 mm. The individual layers (together with a separating layer) each have a layer thickness of 2.5 µm. The layer structure comprises 3200 layers, i.e. 1600 layers per material. After the layers have been created, the NdFeB particles are aligned by means of an external magnetic field with a strength of 1200 kA / m generated with an electromagnet. No pressing takes place. The sintering ("pressless sintering" or "bulk sintering") is carried out over a period of one hour at 400 to 500 ° C. in an argon atmosphere. The body is then divided into parts by cutting with a width of 20 mm by 10 mm and a height of 5 mm. Another magnetization optionally follows.

A second example of a hybrid magnet is a hybrid magnet made of powder, consisting of NdFeB [neodymium, iron, boron] as the hard magnetic material. 90% of the particles of this material have a diameter of less than 3 µm, 50% of less than 2 µm and 30% of 0.2 to 1 µm. Furthermore, the hybrid magnet consists of a composition of 90% Fe [iron], 5% Ni [nickel], 2% Co [cobalt] and 3% Si [silicon] as a soft magnetic material. 90% of the particles of this composition have a diameter of less than 2 μm and 30% of 0.2 to 0.1 μm. The coating is formed from an oxide composition, comprising the following proportions: 40 to 60 mol% PbO [lead oxide], 30 to 40 mol% B ₂ O ₃ [boron oxide], 5 to 10 mol% ZnO [zinc oxide]. The layer structure alternately has one hard magnetic and two soft magnetic layers. The body is 100 mm by 300 mm wide and has a height of 9.9 mm. The individual layers have a layer thickness (together with a separating layer) of 3 µm each. The layer structure comprises 3300 layers, i.e. 1100 layers of the hard magnetic material and 2200 layers of the soft magnetic material. Pressing takes place in the form of a die press. The sintering is carried out for one hour at 400 to 500 ° C in an argon atmosphere. Then the body is divided into parts cut by cutting with a width of 20 mm by 10 mm and a height of 9 mm. Another magnetization optionally follows.

A third example of a hybrid magnet is a hybrid magnet made of powder, consisting of NdFeB [neodymium, iron, boron] as a hard magnetic material with a layer thickness of 300 nm and 90% Fe [iron], 5% Ni [nickel], 2 % Co [cobalt], 3% Si [silicon] as a soft magnetic material with a layer thickness of 350 nm. The separating layers are formed from an oxide composition, comprising the following proportions: 40 to 60 mol% PbO [lead oxide], 30 to 40 mol% B ₂ O ₃ [boron oxide], 5 to 10 mol% SiO ₂ [silicon dioxide] with a separating layer thickness of 10 nm. The layer structure alternately has a hard magnetic and a soft magnetic layer. The body is 10 mm by 25 mm wide and 6 mm high. Alignment takes place in the magnetic field before sintering. The sintering is carried out for one hour at 400 to 900 ° C in an argon atmosphere. Another magnetization optionally follows.

In a fourth example of a hybrid magnet, a layer structure with coating technologies is produced by first growing a thin hard magnetic layer in a first step, e.g. B. from Nd ₂ Fe ₁₄ B [neodymium, iron, boron] with a thickness of 250 to 300 nm. This layer thickness corresponds to a single-domain particle diameter of Nd ₂ Fe ₁₄ B. One of the following coating technologies introduced above can be used: "atomic layer deposition "(ALD)," metal-organic chemical vapor deposition "(MOCVD) or" chemical vapor deposition "(CVD). The following organometallic compounds can be used for these coating technologies: tris- [N, N-bis (trimethylsilyl) amido] neodymium (III) for neodymium [Nd], iron (III) tris (2,2,6,6- tetramethyl-3,5-heptanedionate) for iron [Fe] and triisopropylborate for boron [B]. In a second step, e.g. B. applied by CVD a 5 to 10 nm thin separation layer. Here, for. For example, the following oxides can be used: SiO ₂ [silicon oxide], B ₂ O ₃

[Boron oxide], Na ₂ O [sodium oxide], KO [potassium oxide], Al ₂ O ₃ [aluminum oxide]. Various precursors can be used for this, e.g. B. Tetraethyl orthosilicate (TEOS) for SiO2 [silicon oxide], triethyl borate (TEB) for B ₂ O ₃ [boron oxide], sodium ethoxide for Na ₂ O [sodium oxide], aluminum isopropoxide for Al ₂ O ₃ [aluminum oxide], potassium ethanolate for KO [ Cobalt oxide]. Oxide mixtures with PbO [lead oxide], Bi ₂ O ₃ [bismuth oxide], P ₂ O ₅ [phosphorus oxide], ZnO [zinc oxide] or SnO [tin oxide] can also be used here in order to be able to produce low-melting glasses. For this, e.g. B. the following precursors are possible: lead (II) acetate trihydrate for PbO [lead oxide], bismuth (III) acetates for Bi ₂ O ₃ [bismuth oxide], phosphorus trichloride for P ₂ O ₅ [phosphorus oxide], zinc acetate for ZnO [zinc oxide] , Tin (II) acetate for SnO [tin oxide]. Rare earth oxides can also be built into the separating layer, which in turn arise from precursors such as neodymium (III) isopropoxide and dysprosium (III) acetate hydrate. In a third step, a thin layer of a soft magnetic phase, e.g. B. FeCo [iron, cobalt], FeSi [iron, silicon] or FeNi [iron, nickel] applied, which result from precursors such as iron (III) tris (2,2,6,6-tetramethyl-3,5- heptanedionate) for iron [Fe], silicon tetrachloride for silicon [Si], (Co) bis (cyclopentadienyl) cobalt (II) for cobalt [Co] and (Ni) bis (cyclopentadienyl) nickel (II) for nickel [Ni]. A separating layer of binary, ternary or quaternary oxide mixtures is then applied again, from which a glass, a glass ceramic or a ceramic phase forms in the further course of the process. The sequence of the layer structure is repeated until the desired total thickness is reached. This creates a layer structure in which hard magnetic layers and soft magnetic layers always alternate, which are separated from one another by separating layers.

A fifth example is a hybrid magnet similar to that previously described in the fourth example. The only difference is the sequence and the number of different layers. Instead of always arranging hard magnetic layers and soft magnetic layers alternately, several soft magnetic layers can also be arranged Layers or several hard magnetic layers follow one another, which can also be separated from one another by a separating layer. Adjacent layers of the same material are therefore grouped together.

Fig. 1:

eine schematische Darstellung eines Querschnitts eines Zwischenproduktes eines aus bereits beschichtetem Pulver hergestellten Hybridmagneten vor dem Sintern,

Fig. 2:

eine schematische Darstellung eines Querschnitts des Hybridmagneten aus Fig. 1 nach dem Sintern,

Fig. 3:

eine schematische Darstellung eines mit Beschichtungstechnologien hergestellten Hybridmagneten,

Fig. 4:

eine schematische Darstellung eines Querschnitts eines mit Beschichtungstechnologien hergestellten weiteren Hybridmagneten,

Fig. 5:

ein Flussdiagramm einer ersten Ausführungsform eines Herstellungsverfahrens, und

Fig. 6:

ein Flussdiagramm einer zweiten Ausführungsform eines Herstellungsverfahrens.

The invention and the technical environment are explained in more detail below with reference to the figures. The figures show particularly preferred exemplary embodiments, to which the invention is, however, not limited. In particular, it should be pointed out that the figures and in particular the proportions shown are only schematic. In particular, the particles and the layers are only shown in such a small number that are sufficient to clearly visualize the concepts according to the invention. Show it:

Fig. 1:

1 shows a schematic representation of a cross section of an intermediate product of a hybrid magnet produced from already coated powder before sintering,

Fig. 2:

a schematic representation of a cross section of the hybrid magnet Fig. 1 after sintering,

Fig. 3:

1 shows a schematic illustration of a hybrid magnet produced using coating technologies,

Fig. 4:

1 shows a schematic representation of a cross section of a further hybrid magnet produced using coating technologies,

Fig. 5:

2 shows a flowchart of a first embodiment of a production method, and

Fig. 6:

a flowchart of a second embodiment of a manufacturing method.

Fig. 1 shows an intermediate product of a hybrid magnet 1, having hard magnetic layers 13 and soft magnetic layers 14. The hard magnetic layers 13 are (essentially) formed by hard magnetic particles 2. The hard magnetic particles 2 are (only) made of a hard magnetic material 5. The soft magnetic layers 14 are (essentially) made of soft magnetic particles 3, which themselves (only) are made of a soft magnetic material 6. The soft magnetic material 6 is represented by hatching. The hard magnetic particles 2 and the soft magnetic particles 3 each have a coating 4 made of a magnetically passive material 7. The coating 4 has a coating thickness 8. The hard magnetic particles 2 and the soft magnetic particles 3 each have approximately a diameter 12, which in this embodiment is the same size for all hard magnetic particles 2 and all soft magnetic particles 3. Also shown is a layer thickness 19 as the distance between adjacent layers. Hard magnetic layers 13 have a hard magnetic layer thickness 33 and soft magnetic layers 14 have a soft magnetic layer thickness 16, which does not have to be identical to the hard magnetic layer thickness 33. A width 20 is shown here as the extent of the hybrid magnet 1 perpendicular to the direction in which the layer thickness 19 is measured. The hybrid magnet 1 is in this Fig. 1 shown as a cross section through the layer structure, a situation before the sintering of the hybrid magnet semi-finished product is shown, so that the hard magnetic particles 2, the soft magnetic particles 3 and the coating 4 can still be recognized as such. Also shown is an applied external magnetic field 11 which leads to the alignment of the hard magnetic particles 2 and to the magnetization of the soft magnetic particles 3. The arrows 34 in the particles 2 and 3 indicate the direction of the magnetization. The external magnetic field 11 is homogeneous and encloses the volume of the entire body 17.

Fig. 2 shows the hybrid magnet 1 Fig. 1 after pressing and sintering. From the coating 4 of the hard magnetic particles 2 and the soft magnetic Particles 3 is a matrix body 9 made of the magnetically passive material 7. The matrix body 9 as well as the hard magnetic particles 2 and the soft magnetic particles 3 together now form a sintered part 10. The sintered part 10 is formed from the hard magnetic particles 2 and the soft magnetic particles 3 and the coating 4 by pressing and sintering. The sintered body 10 forms the body 17 of the hybrid magnet 1. The hard magnetic particles 2 made of the hard magnetic material 5 form the hard magnetic layers 13. The hard magnetic particles 2 represent partial regions of the hard magnetic layers 13 which are magnetically passive in the layer plane through the magnetically passive body forming the matrix body 9 Material 7 are separated from each other. The soft magnetic particles 3 made of the soft magnetic material 6 form the soft magnetic layers 14. In between there are separating layers 15, which in this embodiment are formed as part of the matrix body 9. This applies in particular to the first three examples of a hybrid magnet.

Fig. 3 shows a hybrid magnet 1, which has arisen from a manufacturing process using a coating technology. The hybrid magnet 1 comprises a body 17 which comprises hard magnetic layers 13 made of a hard magnetic material 5, soft magnetic layers 14 made of a soft magnetic material 6 and separating layers 15 made of a magnetically passive material 7. The soft magnetic material 6 is represented by hatching. The separating layers 15 have a separating layer thickness 18. The hard magnetic layers 13 and the soft magnetic layers 14 have a layer thickness 19, which in this embodiment is the same for all layers. The width 20 of the hybrid magnet 1 is also shown. Also shown is an external magnetic field 11 which can be applied during the production of the hybrid magnet 1. Fig. 3 relates in particular to the fourth example of a hybrid magnet explained above.

Fig. 4 shows a hybrid magnet 1 in a further embodiment. Compared to Fig. 3 another layer sequence is only shown as an example. Accordingly, adjacent layers of the same material can also be present in groups. Fig. 4 relates in particular to the fifth example of a hybrid magnet explained above. The in Fig. 4 The adapted layer structure shown with grouped layers of the same material can also be applied to hybrid magnets according to the first three examples. Grouped layers can also be provided with such hybrid magnets.

Fig. 5 shows the first embodiment of a manufacturing method described above. In a recipe manufacture 22, starting materials for the manufacturing process are selected and made available in accordance with component and material requirements (in particular with regard to magnetic properties such as, for example, retentive magnetization and a coercive field strength, and with regard to temperature properties such as a transformation temperature). The starting materials are then pulverized in a powder supply 23. This happens e.g. B. with conventional techniques. In a subsequent coating 24 powder particles are coated, for. B. with a single or multiple coating. Furthermore, a green compact is built up layer by layer in a layer structure made of powder 25. A pressing 26 (with or without a magnetic field) optionally follows to form a compact. This is followed by a sintering 27 of the green body, an optional annealing 28, an optional aftertreatment 29 and an optional magnetization 30. The first embodiment of a manufacturing method applies in particular to the first three examples of a hybrid magnet.

Fig. 6 shows the second embodiment of a manufacturing method described above. First, that is for Fig. 5 described recipe manufacture 22 performed. This is followed by building up a layer structure 31 and producing layers using coating technologies 32, which can optionally be carried out in a magnetic field. Finally, as before, the sintering 27, the optional annealing 28, the optional aftertreatment 29 and the optional magnetization follow 30. The second embodiment of a manufacturing method applies in particular to the fourth and fifth example of a hybrid magnet.

The above explanations have shown that the proposed production method and / or the hybrid magnet at least partially overcomes the technical problems described in connection with the prior art. In particular, a hybrid magnet with improved magnetic, mechanical and / or thermal properties was also presented.

Reference list

1

Hybrid magnet

2nd

hard magnetic particle

3rd

soft magnetic particle

4th

Coating

5

hard magnetic material

6

soft magnetic material

7

magnetically passive material

8th

Coating thickness

9

Matrix body

10th

Sinterling

11

External magnetic field

12th

diameter

13

hard magnetic layer

14

soft magnetic layer

15

Interface

16

soft magnetic layer thickness

17th

body

18th

Interface thickness

19th

Layer thickness

20th

Vastness

21

layer

22

Create recipe

23

Provide powder

24th

Coating

25th

Building up a layer structure from powder

26

Press

27

Sintering

28

Annealing

29

Post-treatment

30th

Magnetize

31

Building a layer structure

32

Creating layers with coating technologies

33

hard magnetic layer thickness

34

Direction of magnetization

Claims (13)

1. Method for producing a hybrid magnet (1), comprising at least the following method steps:

   A) producing a hard magnetic layer (13) from a hard magnetic material (5),

   B) producing a soft magnetic layer (14) from a soft magnetic material (6), and

   C) producing a spacer layer (15) from a magnetically passive material (7),
   wherein, by respectively multiple applications of the method steps A), B) and C), a hybrid magnet (1) having a layer structure is shaped;
   wherein method step A) comprises at least the following partial step:
   A1) providing a hard magnetic powder having hard magnetic particles (2) made from the hard magnetic material (5), wherein method step B) comprises at least the following partial step:
   B1) providing a soft magnetic powder having soft magnetic particles (3) made from the soft magnetic material (6), wherein method step C) comprises at least the following partial step:
   C1) applying at least one coating (4) made from the magnetically passive material (7) on at least one of the hard magnetic particles (2) or the soft magnetic particles (3);
   wherein step C) is performed in each case once after every performance of method step A) and in each case once after each performance of method step B).
2. Method according to Claim 1, wherein
   the method furthermore comprises the following method steps:

   D) shaping a body (17), which constitutes the hybrid magnet (1), in accordance with the method steps A), B) and C); and

   E) sintering the body (17), wherein a temperature is used that is sufficiently high to form the coating (4) into a matrix body (9) surrounding the hard magnetic particles (2) and the soft magnetic particles (3),
   wherein, during the entire method, a sintering temperature for the hard magnetic material (5) and a sintering temperature for the soft magnetic material (6) is not exceeded, and wherein, in method step E), a sintering temperature of the magnetically passive material (7) is exceeded.
3. Method according to Claim 1 and 2, wherein the coating (4) has a coating thickness (8) ranging from 1 nm to 300 nm.
4. Method according to one of Claims 2 and 3, wherein the body (17) is compressed into a pellet (10) between method steps D) and E).
5. Method according to Claim 4, wherein the pressing takes place in an external magnetic field (11).
6. Method according to one of Claims 4 and 5, wherein the hard magnetic particles (2) and the soft magnetic particles (3) are acted upon at least temporarily with ultrasound.
7. Method according to one of the preceding claims, wherein the spacer layer (15) has a spacer layer thickness (18) ranging from 1 nm to 300 nm.
8. Method according to one of the preceding claims, wherein the hybrid magnet (1) is magnetized in an external magnetic field (11).
9. Hybrid magnet (1), having a layer structure made of layers (21), wherein at least one of the layers (21) is a hard magnetic layer (13) and at least one of the layers (21) is a soft magnetic layer (14), and wherein adjacent layers (21) are separated by magnetically passive material (7); wherein each hard magnetic layer (13) is constituted of hard magnetic particles (2) having at least one coating made from the magnetically passive material (7); wherein each soft magnetic layer (14) is constituted of soft magnetic particles (3) having at least one coating made from the magnetically passive material (7); and wherein the hard magnetic particles (2) and the soft magnetic particles (3) are surrounded by a matrix body (9), wherein the matrix body (9) is constituted of the magnetically passive material (7).
10. Hybrid magnet (1) according to Claim 9, wherein the hard magnetic particles (2) and the soft magnetic particles (3) have a diameter (12) ranging from 0.2 µm to 250 µm.
11. Hybrid magnet (1) according to either of Claims 9 and 10, wherein the magnetically passive material (7) which constitutes the matrix body (9) is one of the following materials: glass, glass ceramic, metallic glass or ceramic.
12. Hybrid magnet (1) according to one of Claims 9 to 11, wherein each layer (21) has a layer thickness (19) and a width (20), and wherein the width (20) for each layer (21) corresponds to at least ten times the layer thickness (19).
13. Hybrid magnet (1) according to one of Claims 9 to 12, wherein the layers (21) are oriented perpendicular to the direction of magnetization (34) of the hybrid magnet (1).

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