Electrical strip, use of an electrical strip and method of manufacturing an electrical strip

Abstract

This invention relates to an electrical strip having at least one functional layer (4) composed at least partially of a ferromagnetic material and at least one additional layer (8) composed at least partially of a nonmagnetizable material, characterized in that the at least one additional layer (8) and the at least one functional layer (4) are bonded together by an adhesive bond (12) having atomic diffusion (14), and / or characterized in that the thickness of the at least one functional layer (4) is in the range of 2 to 100 µm, preferably 2 to 60 µm. This invention also relates to an application of this electrical strip as a core, and a method for manufacturing an electrical strip. This invention solves the technical problems of providing an electrical strip and a process for producing an electrical strip, thereby improving upon the disadvantages described in the prior art, and specifically, increasing the efficiency of energy conversion in applications as an inductor component.

Description

Technical Field

[0001] Invention Field

[0002] This invention relates to an electrical strip having at least one functional layer composed at least partially of a ferromagnetic material and at least one additional layer composed at least partially of a non-magnetizable material. This invention also relates to the use of an electrical strip and a method for manufacturing an electrical strip. Prior Technology

[0003] Background of the Invention

[0004] Electrical strips and tapes are widely used in all types of electrical systems, such as in generators for power generation, transformers for power transmission and distribution, motors and other motors for energy recovery, and other applications in the field of electrical engineering.

[0005] Electrical strips are specially processed for use as inductive components, such as magnetic cores in motors or transformers. Electrical strips are generally understood to be rolled strips made of magnetic materials, such as iron-silicon alloys. After a multi-stage manufacturing process including, for example, steel production, hot or cold strip processing and, where necessary, heat treatment and strip coating, as well as the finishing process and straightening (stretch-bending straightening) of the strip in the processing line, the electrical strip is longitudinally cut to the width for use and processed into electrical sheets, i.e., individual portions of the electrical strip, by stamping, etching, erosion, wire etching, cutting, waterjet cutting or laser cutting.

[0006] In other processing steps, the electrical sheets are subsequently layered, packaged, and fixed to form electromagnetic components, specifically sheet stacks. These electromagnetic components, as magnetic cores, are used in electrical systems such as generators, transformers, electric motors, and other magnetic applications in the form of stators, rotors, transformers, and other magnetic cores in relays, switches, contactors, chokes, ignition coils, meters, and controllable deflection magnets.

[0007] Numerous properties, such as their geometry, mechanics, and other material properties, are crucial for the intended use of electrical sheets in their respective applications. However, their characteristics in electromagnetic fields are particularly important for the function of individual components. Electrical sheets are generally made of so-called soft magnetic materials, that is, materials that are particularly easy to magnetize in external magnetic fields and thus make optimal use of energy when used in electrical systems.

[0008] The magnetizability of a material is described by its material-dependent absolute permeability µ. The relationship between the magnetic field strength H acting on a magnetic material and the magnetic flux density generated in the magnetic material by H is as follows: In empty space, there exists Where µ0 is the so-called magnetic field constant. It is called the permeability number or the dimensionless quantity of relative permeability. Characterizing the magnetic properties of materials. Ferromagnetic materials are suitable for the following applications. The material amplifies the external magnetic field inside the material. For the construction of motors, ferromagnetic materials are mainly important due to their field amplification effect.

[0009] The magnetizability of ferromagnetic materials is described by the orientation of the B-H curve. A changing magnetic field strength H causes the movement and growth of magnetic domains, i.e., microscopic regions within the ferromagnetic material, where individual atomic or molecular magnetic particles are oriented in the same manner within the material. Because this process occurs within the magnetic material, the orientation of B relative to H changes with increasing magnetic field strength, unlike the orientation that occurs with decreasing magnetic field strength. This deviation from the curve is called hysteresis.

[0010] The type of electrical stripe is determined by the direction of the characteristic curve B relative to H. The rising branch of the characteristic curve (the direction of B as the magnetic field strength H increases) and the falling branch of the characteristic curve (the direction of B as the magnetic field strength decreases) merge at their endpoints to form a hysteresis loop. The area of ​​the hysteresis loop describes the energy required to remagnetize the magnetic material.

[0011] When the external magnetic field H is broken, a certain value of the magnetic polarization J of the portion of the flux density B induced by the magnetic material remains unchanged. This value is called the magnetic coercivity Br. The width of the hysteresis is determined by the coercivity Hc (the field strength necessary to make the flux density zero). During remagnetization, the material state passes through a closed hysteresis loop, the area of ​​which represents the amount of energy (heat) released to the environment per volume of material per remagnetization cycle.

[0012] Therefore, the magnetic properties of components in an electrical system have a decisive influence on its efficiency and thus on energy consumption. Increased efficiency and thus improved energy conversion can be achieved by applying relevant optimizations, particularly regarding the magnetic properties of electrical components, and specifically regarding core losses. Remagnetization loss, or core loss, is a term used to describe the heat loss of magnetic materials in an alternating magnetic field due to changes in magnetization. Changes in magnetization can be caused by alternating current, a magnetic field, or the movement of components made of magnetic materials. For example, the rotor of a DC generator also experiences an alternating magnetic field.

[0013] To date, electrical strips with thicknesses ranging from 1 mm to 0.5 mm, and in some cases down to 0.1 mm, have been produced. Electrical strips with the most likely isotropic properties are used in electrical engineering applications where the magnetic flux is not constant in any particular direction. For such non-grain-oriented (NO) electrical steels, a polycrystalline structure with a grain size between 20 µm and 200 µm is ideal. For applications where particularly low remagnetization loss is critical and where high permeability or polarization is required, uniformly oriented electrical strips with crystalline texture are typically used; these are called grain-oriented (KO) electrical strips.

[0014] In the case of remagnetization loss, eddy current loss and hysteresis loss are fundamentally distinguished. Hysteresis loss refers to the loss describing the work required to shift a magnetic domain during the remagnetization of a magnetic material. This loss is proportional to the area of ​​the hysteresis loop crossed by the B-H curve, and is determined by... , where kH describes the shape factor, which depends on the geometry of the material and the stress during processing (e.g., stamping, bending, drawing). Furthermore, Hc represents coercivity, Bmax represents the amplitude of magnetic induction in the material, f represents the remagnetization frequency, and ρ represents the material density.

[0015] If a conductor is exposed to a changing magnetic field, a voltage is induced, which in turn generates a current. The heat loss caused by this current is called eddy current loss, and according to... To calculate, the material dependency quantity Also known as the eddy current loss factor, where φ represents the specific conductivity (conductivity) of the material, d is the thickness of the electrical sheet, and ρ is the material density of the electrical sheet.

[0016] Therefore, the magnetic properties of the electrical sheet, and specifically its remagnetization loss, are essentially determined by the material-specific parameters and the thickness of the electrical sheet. Iron cores made of solid materials are almost unusable due to high eddy current losses; furthermore, the core heats up as the eddy current frequency increases. To avoid this and reduce core losses, motor cores are designed as laminated, i.e., stacked and insulated electrical sheets within a package, or as wound and cut strip cores.

[0017] To effectively suppress eddy current formation, the laminates of the electrical sheets are coated with an insulating layer, such as varnish. The thickness of this insulating layer is in the range of a few µm, and typically each sheet has a 1 to 2 µm thick insulating varnish layer on each side with a certain degree of roughness. If the electrical sheets are now stacked and bonded, the stack mainly consists of the electrical sheets, but also of varnish and air pockets. The entire volume of the stack (also known as the encapsulation) is therefore not entirely filled with magnetic material.

[0018] The eddy current losses also decrease as the thickness of the electrical steel decreases. However, the production of thin electrical strips increases the demands on the manufacturing process. Furthermore, it should be noted that with extremely thin electrical strips, the ratio between the magnetizable material of the electrical strip and the non-magnetizable material of the coating becomes unfavorable: the more coating material on the surface of the electrical strip relative to its thickness, the less iron is contained in the package at a given height. The worse this ratio, the thinner the electrical steel, and the smaller the ratio of metal sheet to varnish thickness becomes, and beyond a certain point, the positive effects of using particularly thin electrical steel diminish.

[0019] Therefore, electrical strips are produced to meet market demands for manufacturing in varying thicknesses and subsequent processing into electrical sheets. By laminating thin layers of electrical sheets into a core, extremely tight tolerances are required for the sheet or strip thickness, especially for larger core heights. Amorphous electrical steel with thicknesses of 0.50 mm and 0.65 mm is the primary production material, but 0.35 mm and 1.00 mm are also common. For grain-oriented electrical steel, common thicknesses are 0.35 mm, 0.30 mm, 0.27 mm, and 0.23 mm. Furthermore, electrical strips with a nominal thickness of 0.1 mm are known.

[0020] Another important method to reduce core loss is the use of tempered alloys. For example, core loss can be reduced by adding silicon, because the resistivity of magnetic materials increases with increasing silicon content, thus decreasing conductivity. However, increased silicon content is detrimental to the cold formability of electrical steel, and commercial electrical strips are typically cold-rolled, leading to increased requirements for manufacturing and processing. Generally, the silicon content should not exceed 3.5% by weight.

[0021] Besides reducing the sheet thickness and using tempered alloys, other suitable measures to improve the material properties of electrical sheets include adjusting the microstructure properties, especially in terms of grain size and texture. However, this adjustment has a major negative impact on the mechanical properties of the electrical sheet and therefore on its machinability.

[0022] Therefore, the present invention addresses the technical problem of providing an electrical strip of the type mentioned at the beginning and a method for producing the electrical strip, which improves upon the shortcomings of the prior art and, in particular, increases the efficiency of energy conversion in applications as inductor components. Summary of the Invention

[0023] Invention Summary

[0024] According to the first teaching, the aforementioned technical problem is solved in an electrical strip having at least one functional layer composed at least partially of ferromagnetic material and at least one additional layer composed at least partially of nonmagnetizable material, because the at least one functional layer and the at least one additional layer are bonded together by an adhesive having atomic diffusion.

[0025] In the following text, "electric strip" should be understood as, for example, at least two layers of electrical strip, or at least two layers of electrical sheet cut from such an electrical strip. Electrical strips can also be used to construct electrical sheets. Due to their ferromagnetic properties, the various specified types of electrical strips and electrical sheets are used as inductor components in motors or in transformers or transformers.

[0026] In principle, the properties of the electrical strips described below are generated by the few layers mentioned. For example, it is preferable to have an additional layer between two functional layers. Alternatively, three to ten functional layers can be provided, each with two to nine additional layers disposed therebetween. As described below, two functional layers can also be adjacent to each other and then separated from other functional layers by additional layers.

[0027] Furthermore, the electrical strip is preferably made of multiple functional layers and additional layers, which are arranged adjacent to each other and preferably alternately. Typically, 10 to 100 functional layers with a corresponding number of additional layers can be stacked. However, the number of layers is not limited in principle, but is limited by the feasibility of production.

[0028] Within the scope of this invention, it is recognized that bonding at least one functional layer and at least one additional layer by means of an adhesive with atomic diffusion can provide an electrical strip with improved material properties, specifically improved magnetic properties. By means of this bonding, internal stress at the transitions of the bonded components and thus within the electrical strip or sheet can be reduced.

[0029] Bonding via adhesives with atomic diffusion should be understood as a transition layer formed by the atomic diffusion of the bonding materials of the bonding complexes, creating a bond between two bonding complexes in the bonding region. This transition layer facilitates the continuous adjustment of material properties. Atomic diffusion adhesive bonding is thus achieved by forming a transition layer between layers.

[0030] In the transition layer, the atoms of the bonding agents gradually mix, and the bonding occurs through a spatial variation process (diffusion) within the transition layer (also known as the bonding region). This transition layer causes a reduction in internal tension. The extent of the transition region depends on the individual bonding agents used, and especially the diffusion properties of the materials involved.

[0031] To characterize the bonding and properties of adhesives with atomic diffusion (i.e., the bonding regions of adhesives in the transition layer), various analytical methods can be applied. These methods include optical microscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), secondary ion mass spectrometry (SIMS), and microhardness profile analysis.

[0032] For example, this composite may be referred to as a coated composite. Preferably, the two bonding agents are metallic materials, and the coated composite represents the metallic bonding of the two bonding agents or the coating agent. However, composites between metallic materials and non-metallic materials such as carbon-containing materials or non-metallic bonding agents such as plastics are also possible. The bonding agents of the composite are mainly disposed in layers adjacent to each other. The bonding of the bonding agents in the coated composite can be achieved by coating. For this purpose, coating can be achieved by cold rolling coating or hot rolling coating.

[0033] Alternatively, the bonding components can also be joined by soldering metal encapsulation (specifically, diffusion soldering or electric soldering) or by encapsulation and partial soldering. Furthermore, production via sintering or hot-pressing (HIP) is also possible.

[0034] According to the invention, at least one functional layer is at least partially, preferably entirely, composed of a ferromagnetic material, specifically iron, nickel, cobalt, other ferromagnetic materials, alloys thereof, or a coating of two or more of these materials. Even in the case of substantially paramagnetic materials such as copper, for example, ferromagnetic properties are known to be induced by appropriate treatment of the metal. In this case, the material is also suitable for producing the functional layer.

[0035] In this regard, it is preferable that the functional layer be designed as a continuous layer to achieve its properties in the most probable way. However, the functional layer can also be designed as a discontinuous layer, since the continuity of the layer cannot be fully guaranteed during production. On the other hand, depending on the materials used, the production of functional layers designed as discontinuous layers can also be carried out such that the material of the additional layer at least partially penetrates the material of the functional layer. In this way, other properties of the composite, such as electrical conductivity or durability, can be improved. The material of the functional layer can also contain other non-ferromagnetic components and inclusions.

[0036] Similarly, at least partially, and preferably entirely, of a nonmagnetizable material should be understood as a layer designed to be either a continuous or discontinuous layer. This also applies where a continuous layer is required, and preferably to a certain extent, to achieve the properties of the additional layer in the most probable manner. The at least one additional layer may also contain materials other than nonmagnetizable materials. Specifically, both the at least one functional layer and the at least one additional layer may contain open or closed pores, such as air pockets.

[0037] At least one additional layer may consist of one layer or at least two layers. Preferably, at least one additional layer is a sheathing material or a multilayer composite material. Particularly preferred, at least one additional layer comprises a mica layer or a graphene layer on a copper or aluminum metal layer. Fiber composite materials, ceramic materials, or layered silicates (mica) may also be used as materials for at least one additional layer, thereby specifically introducing electrical insulation into the electrical strip or electrical sheet.

[0038] Specifically, if the additional layer is designed to be a discontinuous additional layer, providing at least one such additional layer can also advantageously affect material properties, such as the magnetic properties of the electrical strip. The discontinuous additional layer can contact the functional layer disposed on both sides of the at least one additional layer.

[0039] Alternatively, at least one additional layer is preferably formed as a continuous layer, thereby preventing contact between the functional layers disposed on both sides of the at least one additional layer. Providing at least one continuously formed additional layer and providing at least one discontinuously formed additional layer can both have a particularly good effect on the material properties of the electrical strip, and specifically its magnetic properties. Specifically, it can reduce the magnetization loss of the electrical steel core.

[0040] The material of at least one functional layer may comprise an iron-silicon alloy. Such alloys have proven advantageous for electrical strips, and specifically for electrical sheets, particularly regarding remagnetization losses. The functional layer may have a grain-oriented microstructure or an amorphous microstructure. Alternatively, the material of at least one functional layer may also comprise other iron (Fe) alloys and alloys of cobalt (Co), aluminum (Al), and / or nickel (Ni).

[0041] In a preferred manner, the production of the functional layer aims to generate as many large grains as possible, preferably up to the size of multiple layers in thickness. Furthermore, depending on the material of the additional layers, the diffusion of elements and their implementation within the lattice of the functional layer material are possible.

[0042] Using the composite material described above, electrical strips comprising functional layers and / or additional layers made of different materials can be provided, preferably comprising functional layers made of different ferromagnetic materials and additional layers made of different nonmagnetizable materials. Specifically, the different materials may have different material properties, for example, different properties regarding electrical or thermal conductivity and material density. In this way, specific selection of material properties is possible, and if advantageously selected and combined, the magnetic properties of the electrical steel can be particularly improved.

[0043] Within the scope of this invention, specifically, it is recognized that reverse losses, and more specifically, hysteresis losses and eddy current losses, can be reduced by means of an adhesive with atomic diffusion, combined with the composite according to the invention. Preferably, the introduction of additional layers reduces electrical stripes caused by… The given eddy current loss and its origin The given hysteresis losses, specifically ρ and φ, are used to reduce the overall core magnetization loss. This reduction in core magnetization loss, specifically hysteresis loss and eddy current loss, can be observed at frequencies ranging from 1 kHz to 10 kHz. The possible frequency range depends on the specific materials of the functional layer and / or additional layers.

[0044] Compared to measurements of relatively thick electrical sheets without additional layers, a reduction in hysteresis loss can be observed, particularly by reducing the area of ​​the hysteresis loop crossed by the B-H curve of the composite having at least one functional layer and at least one additional layer according to the present invention. Furthermore, the coercive magnetic field strength can be influenced by the composite via atomically diffused adhesive bonding. Regarding the reduction in eddy current loss, the eddy current loss factor was observed. The reduction.

[0045] Furthermore, by providing at least one additional layer made of a non-magnetizable material, other material properties of the electrical strip, besides its magnetic properties, can be specifically affected. For example, it is possible to reduce the weight of the electrical strip by using at least one additional layer with a lower material density ρ compared to the material of the functional layer. This reduction in weight advantageously leads to further improvements in the energy efficiency of the electrical strip, particularly when the electrical strip is used as an electrical plate in a moving component.

[0046] Furthermore, the thermal conductivity of the electrical strip can be specifically affected by providing at least one additional layer. For example, the material used for at least one additional layer can have a higher thermal conductivity than the material used for at least one functional layer. In this way, the thermal conductivity of the electrical strip can be improved, enabling it to operate under higher thermal loads compared to an electrical strip without at least one additional layer.

[0047] Furthermore, the bonding according to the invention, achieved by means of an adhesive with atomic diffusion, allows for a reduction in the thickness of the magnetically effective functional layer of the electrical strip. This is particularly advantageous for achieving lower core magnetization losses due to the quadratic dependence of the eddy current loss factor on the thickness d of the individual functional layers of the electrical steel.

[0048] According to the second teaching, the technical problem mentioned above is solved according to the present invention in an electrical strip having at least one functional layer composed at least partially, preferably entirely of ferromagnetic material and at least one additional layer composed at least partially, preferably entirely of nonmagnetizable material, wherein the at least one additional layer and the at least one functional layer are preferably bonded to each other, wherein the thickness of the at least one functional layer is in the range of 2 to 100 µm, preferably 2 to 60 µm.

[0049] In principle, the properties of the electrical strip described below are also generated by the few layers mentioned herein. However, preferably, the electrical strip is made of multiple functional layers and additional layers, which are arranged adjacent to each other and preferably alternately. Typically, 5 to 100 functional layers with a corresponding number of additional layers can exist in a stacked form. However, the number of layers is not limited in principle, but is limited by the feasibility of production.

[0050] It is recognized that core magnetization losses can be significantly reduced by means of such electrical strips having at least one functional layer with a thickness ranging from 2 to 100 µm, preferably from 2 to 60 µm. Specifically, the significant reduction in eddy current losses is achieved by the thickness of the functional layers: the eddy current loss factor kwirbel = φ * d2 / (6 * ρ) is quadratically dependent on the thickness d of the individual functional layers. By providing at least one functional layer of such thickness, partially, preferably entirely composed of magnetizable material, and at least one additional layer of non-magnetizable material, the thickness of the individual functional layers of the electrical strip with eddy current losses is reduced. However, the total thickness of the functional layers can then substantially correspond to that of conventional electrical sheets. Therefore, the described electrical sheet can have the same magnetic effect as the inductor component of a conventional electrical strip, but with lower energy loss. This is because of the eddy current loss factor and therefore the eddy current losses can be significantly reduced. This achieves particularly efficient energy conversion.

[0051] Furthermore, it is generally accepted that by providing at least one functional layer with the aforementioned thickness, the coercive magnetic field strength can also be affected, and hysteresis losses can be reduced. Specifically, providing at least one functional layer with the aforementioned low thickness allows the magnetically effective layer to be separated from the fixed total thickness of the electrical strip, thereby spatially restricting the propagation of eddy currents.

[0052] Preferably, in the electrical strip described above according to the second teaching of the invention, at least one additional layer and at least one functional layer are bonded together by an adhesive having atomic diffusion. In this way, an electrical strip can be provided whose bonding is attributable to the advantages of bonding by an adhesive having atomic diffusion and the low thickness of at least one functional layer. This advantageously results in a particularly significant reduction in core magnetization loss. Specifically, in addition to magnetic properties, improved material properties can also be achieved by the described composite. For example, the adhesive bonding achieves a reduction in internal stress and an increase in the adhesive strength between individual layers.

[0053] In another embodiment of the electrical strip, the thickness of at least one additional layer is in the range of 2 µm to 100 µm, preferably in the range of 2 to 60 µm. By introducing at least one, preferably several, additional layers of such small thickness, the material properties of the composite material can be particularly affected. Specifically, providing at least one or several additional layers allows the material of the functional layers to diffuse through the additional layers. For example, if the additional layers have an electrically insulating material, the diffusion of the material of the functional layers through the additional layers can eliminate the electrical insulation between the functional layers. The thermal conductivity between these layers can also be improved by diffusion.

[0054] When designing functional layers and additional layers, the goal is to form them as continuous layers. However, the magnetic properties can also be improved by using at least one or more additional layers that are not formed as continuous layers, and specifically, magnetic backlash losses, especially hysteresis losses and eddy current losses, can be reduced compared to conventional electrical strips. Furthermore, it is possible to achieve contact between functional layers, such as electrical contact. This can further positively influence the electromagnetic properties of the electrical strip, especially for the specific geometry of the components made from it, particularly in applications requiring electrical strips made of composite materials with variable thickness and good conductivity.

[0055] According to another embodiment of the electrical strip, at least one additional layer is at least partially, preferably entirely, composed of a metallic material. By using a metallic but non-magnetic material for the material of at least one additional layer, a particularly adhesive metallic bond with atomic diffusion can be achieved. This results in an increase in the resistance of the electrical strip and thus a longer service life. Overall, a particularly resource-efficient electrical strip is thus specified. Since metals have significantly good electrical and thermal conductivity, the electrical and / or thermal conductivity of the electrical strip can also be increased in this manner, depending on the metallic material used.

[0056] In another embodiment, at least one additional layer has copper (Cu), preferably with a copper content ranging from 1% to 15% by weight. Copper is characterized by its high thermal conductivity, which allows for the designation of electrical strips with improved thermal conductivity.

[0057] In another embodiment of the electrical strip, at least one additional layer has aluminum (Al), preferably with an aluminum content ranging from 1% to 15%, specifically from 3% to 15% by weight. Aluminum also has high thermal conductivity, so that an electrical strip with improved thermal conductivity is also specified in this manner.

[0058] Electrical strips with improved thermal conductivity allow for improved heat dissipation, such as heat generated by induced eddy currents. Overall, heat generated by electrical steel can thus be dissipated more effectively due to remagnetization losses. Furthermore, heat can be better distributed within electrical components where the electrical strip functions as an electrical plate. Since heat loss increases with motor speed and frequency, electrical strips or plates made from them are particularly advantageous for applications requiring high frequencies and speeds.

[0059] Furthermore, it is advantageous to provide at least one additional layer containing a certain proportion of aluminum, because aluminum has a low density compared to other metallic materials. Therefore, providing at least one additional layer containing a certain proportion of aluminum reduces the weight of the electrical steel. This weight reduction allows for greater flexibility in the application of electrical strips or sheets in electrical and electronic components. This is particularly advantageous when using electrical strips for moving electrical components or electronic elements, as it saves energy used for moving these components.

[0060] In another embodiment of the electrical strip, at least one additional layer comprises zirconium (Zr). Zirconium is characterized not only by its high thermal conductivity but also by its good corrosion resistance. In this way, both the durability and thermal conductivity of the electrical strip are increased. Furthermore, the fact that zirconium is relatively soft and flexible makes it easier and more efficient to process at least one additional layer and / or the electrical strip, for example, by rolling, forging, and hammering.

[0061] Furthermore, at least one additional layer may have a specific thermal conductivity that is at least equal to, and preferably greater than, the specific thermal conductivity of at least one functional layer. In this way, an overall improved thermal conductivity of the electrical strip is achieved, resulting in the advantages previously described.

[0062] In other embodiments, at least one additional layer is at least partially, preferably entirely, composed of austenitic alloy or austenite (referred to as austenite). By providing at least one additional austenite layer, a reduction in magnetic reversal losses, specifically hysteresis losses and eddy current losses, can be achieved. By providing at least one additional layer of this paramagnetic material, the two functional layers of the electrical strip with the additional layer disposed therebetween can be magnetically separated, i.e., isolated, from each other. Specifically, this results in a reduction in eddy currents induced by electromagnetic induction.

[0063] Furthermore, providing at least one additional wostenite layer is advantageous because wostenite possesses favorable mechanical properties, such as high formability, and is therefore easy to handle. This simplifies the production of the electrical strip and provides increased flexibility for applications. wostenite steel or alloys also exhibit high resistance to corrosive environmental conditions, particularly corrosion attacks. Therefore, the resistance of the electrical strip can be increased, and its service life extended.

[0064] Specifically, it has proven advantageous to provide at least one additional voss field that has been heat-treated at a temperature in the range of 650 to 1000°C, preferably 670°C or 1000°C.

[0065] In other embodiments, at least one additional layer is at least partially, preferably entirely, composed of Damascus steel. The use of Damascus steel allows for the combination of different steels with varying advantages within a single material. For example, at least one additional layer can therefore be made of a material that is flexible and has cuttable properties. This is advantageous for the handling and subsequent application of the electrical strip.

[0066] Furthermore, at least one additional layer may be at least partially, preferably entirely, composed of a nonmetallic material, preferably a carbon (C) material, and specifically, preferably graphene or graphite. Nonmetallic materials typically have extremely low to negligible electrical conductivity, making them well-suited as at least one additional layer for insulating at least one functional layer. The use of nonmetallic materials can also positively influence other material properties of the electrical strip.

[0067] Due to the inherent high thermal conductivity of graphene or graphite, an electrical steel with improved thermal conductivity is specified according to one embodiment, allowing heat generated in the electrical strip to be dissipated more quickly, for example, through a loss-making process. Additionally, graphene or graphite is a highly flexible, pliable, transparent, and extremely tensile material, thereby improving the mechanical properties, and specifically the processability, of composite materials comprising at least one functional layer and at least one additional layer.

[0068] In another embodiment, at least two functional layers have different ferromagnetic materials, and / or at least two additional layers have different nonmagnetizable materials. In this way, it is possible to provide an electrical strip with high flexibility due to different material combinations and therefore the potential for optimization with respect to different applications. For example, it is possible to provide a higher proportion of certain alloying elements in the outer layer of the electrical strip, which, for example, helps to improve the corrosion resistance of the outer layer.

[0069] Furthermore, preferably, the material properties vary in at least one functional layer and / or at least one additional layer. Thus, different ferromagnetic properties or different electrical or thermal conductivity can be defined and achieved on the surface of the layers. For this purpose, different materials are disposed in sections of one of the layers before bonding, and these materials bond together after bonding, specifically after plating. Therefore, for example, for a particular electric motor design, a stator can be produced in which at least one additional layer containing copper with high thermal conductivity is disposed inside the motor to dissipate the generated heat, and at least one additional layer containing aluminum is disposed outside the motor to reduce weight.

[0070] It is also possible to alter the proportions of alloying elements with different diffusion properties within these layers, for example, in different additional layers and / or different functional layers. As the heat input from the outside gradually decreases into the interior of the material, it is thus possible to achieve uniform thermal diffusion across the entire thickness of the electrical strip. Alloying elements acting as diffusion barriers can also be introduced into individual layers. In this way, the electrical properties can be specifically affected in different regions of the electrical strip, especially during the production of the electrical strip.

[0071] Preferably, different regions of the three-dimensional structure of the electrical strip possess different material properties, specifically different magnetic properties. This allows for the creation of patterns of conductive and / or magnetically bonded regions within the electrical strip. Furthermore, alloying elements can be introduced to specifically influence the microstructure, for example, by binding impurities at grain boundaries. In this way, purer materials, specifically purer functional layers, can further reduce the electromagnetic losses of the electrical strip. Specifically, by providing an anisotropic microstructure, different material properties can be achieved both in directions parallel to the layer plane and in planes orthogonal to the layer plane.

[0072] Furthermore, when using several functional layers, at least two or more functional layers may have different thicknesses. Similarly, when using several additional layers, these additional layers may have different thicknesses. In this way, electrical strips with high geometric flexibility are specified for targeted adaptation to the available installation space in individual applications. Therefore, the optimal material properties of the electrical steel can be adjusted with particular fine precision.

[0073] According to another preferred embodiment for solving the technical problem mentioned above, an electrical strip, specifically an electrical sheet, is provided, wherein at least two electrical strips are arranged in a stacked manner, and wherein a separation layer, specifically a coating layer, is disposed between the at least two electrical strips, and wherein the electrical strips are formed according to one of the foregoing embodiments.

[0074] This type of configuration or stack is also known as laminated stacking and can be used, for example, as part of the stator and / or rotor of an electric motor. Due to the improved properties of the individual electrical strips, specifically regarding remagnetization losses, power transmission can be improved by means of thin-layer stacking when conducting and amplifying magnetic fields. Separating layers are used to insulate the individual electrical strips from each other and also to optimize the efficiency of the laminated stack by reducing core magnetization losses.

[0075] According to other teachings, the technical problems described above are also solved by using electrical strips, specifically electrical plates, as iron cores, wherein the electrical strips are formed according to one of the examples and variations explained above. Specifically, electrical plates are used as iron cores in electromagnets, specifically transformers or transformers, or in electric motors, or in relays, switches, contactors, choke coils, ignition coils, meters, and controllable deflection magnets.

[0076] The iron core, also known as a magnetic core, is understood as a component that, together with electrical conductors and mechanical parts, can be used to manufacture electrical or electronic components, also called inductors. A key characteristic of iron cores made from electrical sheets is their scalability and wide range of applications, from matchbox-sized main transformers to transformers and electric motors to power plant generators.

[0077] Using an electrical strip as a core, as described in one of the previously explained examples and variations, allows for greater flexibility in the size of electrical or electronic components while optimizing energy conversion. Specifically, by using at least one functional layer with the aforementioned low thickness, the thickness of the electrical strip can be flexibly designed and, specifically, reduced. Furthermore, it is recognized that by using an electrical strip as a core, the core magnetization loss, specifically hysteresis loss, and eddy current loss of the core can be reduced. By constructing the electrical strip as a composite material comprising at least one functional layer and at least one additional layer as described above, eddy currents induced by electromagnetic induction are spatially confined to at least one functional layer, thereby reducing eddy current losses.

[0078] It is also particularly advantageous to use several electrical strips, for example, as a core, which can be configured in a stack, one on top of the other. The stacked electrical strips can be glued together by means of a release layer (specifically, a varnish layer) or otherwise bonded together.

[0079] By means of electrical strips characterized by adhesiveness through atomic diffusion forming the bonds described above, material properties that have a decisive influence on the design parameters of the core can be specifically influenced. For example, the weight of the core can be reduced by providing at least one additional layer with a material density lower than that of at least one functional layer. Furthermore, electrical strips and thus the core with improved thermal conductivity can be achieved by specific material selection for at least one additional layer and by means of the composite described. This is particularly advantageous for high power densities, which can rapidly lead to core overheating. Therefore, the use of the described electrical strips also enables the operation of electrical or electronic components at higher temperatures. Overall, by using the described electrical strips as the core, energy conversion can be made more efficient.

[0080] Advantageously, the described electrical strip can be used as a core for low-frequency (at most a few kHz line frequency) applications and for high-power and ultra-high-power applications in the megawatt range. Specifically, the electrical strip described above can be advantageously used as a core in stators or transformers, and is commonly used in motors. Other properties of the core (such as tensile strength) can also be affected by suitable material selection.

[0081] According to the present invention, the above-mentioned technical problems are also solved by a method for producing electrical strips, wherein at least one functional layer is provided, wherein at least one additional layer is provided, wherein the at least one functional layer and the at least one additional layer are arranged adjacent to each other, specifically one on top of the other, and wherein an adhesive bond with atomic diffusion is produced between the at least one functional layer and the at least one additional layer by applying pressure.

[0082] This process enables individual composite structures of layers of different materials and variations in the thickness of individual layers, wherein the layers have high adhesion to each other. Specifically, at least one functional layer and at least one additional layer are combined to form a composite material. Overall, the properties of the electrical strip can therefore be tailored to various applications. Specifically, the magnetic properties of the electrical steel can be positively influenced by the specific selection of layer materials, and core magnetization losses, especially eddy current losses and hysteresis losses, can be reduced. Furthermore, by selecting materials with different thermal expansion, the so-called operation and resulting load between these layers can be positively affected. For example, the total thermal expansion of the electrical steel can be reduced by balancing the thermal expansion between these layers. This allows for the optimized design of components, such as motor components, in which the electrical strip is used as an electrical sheet.

[0083] In this process, a material different from that of at least one additional layer is used in at least one functional layer. Therefore, the composite material is produced with properties between extremes of the specific properties of the combined materials. It is also possible to modify the layer thickness of individual layers using the process mentioned above, allowing for targeted further influence on the desired properties of the electrical strip.

[0084] Preferably, at least one functional layer is at least partially, and preferably entirely, composed of a ferromagnetic material, specifically one of the ferromagnetic materials mentioned above. More preferably, at least one additional layer is at least partially, and preferably entirely, composed of a non-magnetizable material, specifically one of the materials mentioned above. Other combinations of materials, such as metallic or carbon-containing materials, specifically graphene, are also possible.

[0085] This method also enables the production of electrical strips having several functional layers and several additional layers, wherein the functional layers and additional layers are preferably arranged in an alternating order. For example, it is possible to produce composite materials with insulating additional layers. Preferably, an adhesive bond with atomic diffusion is created between an additional layer and a functional layer by applying pressure.

[0086] Alternatively, several functional layers or additional layers can be arranged adjacent to each other, such that the thickness of a layer composed of similar layers can be varied by using layers with uniform thickness. For example, by arranging multiple functional layers one on top of another, a functional layer with a variable thickness, which is a multiple of the thickness of a single functional layer, can be produced. Furthermore, by arranging several additional layers on top of each other, an insulating effect can be increased relative to the functional layers adjacent to the additional layers.

[0087] In the aforementioned process, a combination of additives is used, in which at least one functional layer and at least one additional layer are arranged close to each other and in close contact, specifically closer to atomic distances. The layer stacking can be performed prior to a cleaning process, in which the contacting surfaces are cleaned of impurities such as absorbed gases, oxide layers, or oil residues.

[0088] Cleaning processes, specifically the removal of oxide layers, increase the bonding capacity of the surfaces of the binders. The oxide layer and general surface layer of the binders can also be increased by cracking or roughening, for example, through other processes such as forming processes. Other processes such as rolling or stretching are also used to solidify the areas of the binders near the surface and produce highly reactive surfaces.

[0089] By applying pressure, the surfaces to be bonded are brought into close contact over a large area. This pressure can also be applied in conjunction with other processes, such as forming processes. Bonding is formed by adhesive bonding between the bonding agents through mixing via atomic diffusion, thereby creating a transition layer on which material properties are continuously adjusted. Furthermore, it is possible to introduce other energy in the form of heat, which can enhance atomic diffusion. However, adhesive bonding with atomic diffusion can also be achieved without introducing additional heat. The introduction of pressure (e.g., by pressing the bonding agents together) and the introduction of other energy (e.g., in the form of heat) can occur simultaneously or at different times.

[0090] The introduction of other energies can also affect the expansion of the transition layer, which is generally dependent on the individual materials of the bonding agents. Increased expansion and enhanced atomic diffusion can specifically influence the material properties of electrical strips. For example, increased expansion and enhanced atomic diffusion lead to greater mixing in the composite material, which can promote increased electrical and / or thermal conductivity and dimensional stability in electrical steels.

[0091] Furthermore, the introduction of energy and heat can specifically affect the microstructure of composite materials. For example, recrystallization of the material, such as at least one functional layer and / or at least one additional layer, can occur. The degree of consolidation of the material, such as at least one functional layer and / or at least one additional layer, can also be affected.

[0092] The process described above can be understood, for example, as a coating process; therefore, in English usage, the term "coating" is primarily used to describe this process. Essentially, the process described above produces a metallic bond of two bonded materials at a time. It can also produce an adhesive bond of atomic diffusion between a metallic material and a non-metallic material, such as a carbon-containing material, or between non-metallic materials.

[0093] According to a preferred embodiment of the process, at least one of at least one functional layer and / or at least one of at least one additional layer is heat-treated. Heat treatment can particularly affect material properties, specifically the microstructure. Individual or multiple layers may be heat-treated individually prior to bonding, or multiple layers may be heat-treated together during or after bonding.

[0094] The heat treatment of individual layers prior to bonding can specifically affect the material properties of only some of a plurality of electrical strip layers (e.g., outer configuration layers). Therefore, the microstructure and resulting electromagnetic properties of individual layers can be specifically altered. For example, heat treatment can lead to increased grain growth or the formation of precipitates of individual elements (especially alloying elements).

[0095] Heat treatment during the bonding process can increase atomic diffusion between layers and thus increase the adhesive strength of the layers to be bonded. Further adjustments to the material properties, specifically the microstructure, can be made through heat treatment after bonding, and the adhesive strength can also be further increased in this manner.

[0096] In another preferred embodiment of the process, at least one functional layer and at least one additional layer are bonded together by cold rolling. In this manner, it is possible to separate the forming and diffusion processes during the production of the electrical strip. Furthermore, the composite formed by cold rolling can be further processed similarly to that formed from a homogeneous material.

[0097] In the cold rolling cladding process, the bonding materials, such as at least one functional layer and at least one additional layer, can be pre-treated. Here, the material to be cladding is degreased and activated close to the cladding process, typically by brushing with a wire brush. For some materials, activation may not be necessary. In the next step, the layers to be bonded are cold rolled together, thereby achieving a significant reduction in thickness and a considerable elongation of the material combination.

[0098] Before and / or during cold rolling, a temperature of 50 to 500°C is preferred if heating at least one of the layers is advantageous. Preheating can also be performed by indirect material heating using the equipment in which the cold rolling is being carried out. Preheating does not correspond to hot rolling because the temperature is chosen within the melting point range. The preheating temperature induces improved reactivity on the layer surface, resulting in better bonding of the layers. The temperature generated during cold rolling due to the stretching of the material and surface fracture then falls within, for example, a range of up to 400°C. Additional heating at temperatures below the recrystallization temperature of the rolled material can also be provided during cold rolling.

[0099] By applying high pressure during rolling, new highly active surfaces can be created between the layers to be bonded while air is expelled, and these highly active surfaces can come into close contact with each other. The adhesive force, mechanical interlocking, and bonding that have already begun at certain points can achieve the initial adhesion of the layers to be bonded.

[0100] Following the coating process, adhesion annealing or diffusion annealing can occur directly, where heat treatment activates or strengthens rearrangement processes at atomic energy levels, transforming incompletely adhered layers into bonds. However, for some material combinations, the adhesion generated during coating is sufficient, eliminating the need for adhesion annealing. In the case of heat treatment, process parameters can be optimized to avoid or minimize any potential intermetallic layers. Furthermore, materials that can be strongly strain-hardened by the coating process can recrystallize. Thus, the forming potential necessary for further processing of the material is restored.

[0101] In other steps, the composite material can be rolled almost to its final thickness. Further heat treatment can also be performed to adjust the strength and microstructure properties of the electrical steel. In the case of extremely thin final dimensions, due to the high overall deformation, several rolling and / or annealing cycles may be necessary. On the other hand, especially in the case of thicker final dimensions, it is also possible to directly plate to the final thickness, eliminating the need for subsequent rolling processes.

[0102] This can be followed by full-face rolling, precision pressing with lower deformation, and stretch bending processes, where the material composite may lack any tensile elongation that can occur in the soft-annealed state. By using different roller roughnesses, specific surface finishes—from rough to bright, or isotropic or structured—can be simultaneously set, for example, through laser structuring (etching) of the surface or indirectly through laser structuring (etching) of the rollers used. Full-face cutting can also be eliminated, especially when specific surface finishes are not critical.

[0103] In addition, specifically as a final process step, cutting may be provided, in which the material is cut to the final width and / or trimmed at the edges.

[0104] According to an alternative embodiment of the process, at least one functional layer and at least one additional layer are bonded together by hot rolling. In hot rolling, the layers are bonded at a temperature above the recrystallization threshold during the hot pressing process. For this purpose, the layers to be bonded are typically bonded together into a package before rolling and hot-rolled out as a complete unit. The bonding can be simultaneously produced by a diffusion process that requires a certain temperature for activation.

[0105] According to another alternative embodiment of the process, at least one functional layer and at least one additional layer are bonded together by explosive coating. By means of explosive coating, no heat energy is introduced during the coating process, thereby preventing the formation of brittle intermetallic phases.

[0106] Regardless of the specific embodiments of the processes described above, electrical strips are typically in strip form after bonding. The strip-form electrical strips may be further processed after the processes according to the invention, specifically after plating, such as shaping, cutting to size, and bonding. Due to their good adhesive properties, it is possible to form electrical strips resembling homogeneous materials. Typically, the forming processes used are rolling, bending, deep drawing, stretch forming, hydroforming, or roll forming.

[0107] Furthermore, mechanical separation, such as cutting or stamping, is possible. Thermal cutting and laser processing are also feasible. Additionally, chemical etching, wire etching, or waterjet cutting can be used. These processes advantageously do not increase or only minimally increase the k-shape factor in the calculation of core magnetization loss. Providing an additional layer, specifically comprising a non-magnetizable material, preferably an aluminum-containing material, can also provide advantages regarding the material properties affected by the separation process. For example, providing an additional layer comprising a corrosion-resistant material, such as a material containing aluminum or other reactive alloying elements, can delay corrosion, especially at the cut edges of the electrical sheet.

[0108] Individual electrical strips can be joined to form a package, which is commonly referred to as a package body. A package consisting at least partially, and preferably entirely, of at least one electrical strip according to the invention allows for further processing that remains virtually unchanged in known standardized processes, so that no adaptations are needed to any other possible process steps following the process according to the invention.

[0109] A single-stage process known as stamping packaging is also available, in which electrical steel is stamped out, placed on a stack, and joined to the stack. Simple Explanation of the Diagram

[0110] Other features and advantages of the present invention will become apparent from the following description of examples of embodiments accompanied by the accompanying drawings.

[0111] Show in the diagram Figures 1a to 1d illustrate various embodiments of the electrical strip in the form of an electrical sheet according to the present invention. Figures 2a and 2b schematically illustrate the steps of an embodiment of the method according to the present invention for manufacturing electrical strips in the form of electrical sheets. Figures 3a and 3b show the test results for various electrical strips in the form of electrical sheets, and Figures 4a and 4b show the hysteresis measurement of various electrical strips in the form of electrical sheets. Implementation

[0112] Detailed Description of Preferred Embodiments

[0113] In the following description of various embodiments of the present invention, components and elements having the same function and the same mode of operation are given the same reference numerals, even though such components and elements may differ in size or shape in various embodiments.

[0114] The embodiments relate to electrical sheets described as examples of electrical strips.

[0115] Figures 1a to 1d first illustrate various embodiments of the electrical sheet 2 according to the present invention.

[0116] Figure 1a shows a partial micrograph of the structure of an electrical sheet 2, which has several functional layers 4 and additional layers 8 made of ferromagnetic material, arranged one on top of the other, with the functional layers 4 and the additional layers 8 arranged in an alternating order.

[0117] Functional layer 4 is made of DD11 (1.0332) grade ferromagnetic hot-rolled steel. The grain structure of the ferromagnetic material in functional layer 4 is characterized by grain sizes of less than 100 µm, with many grain sizes ranging from 20 to 50 µm.

[0118] In this example, the additional layer 8 is designed as a continuous layer, separating the functional layers 4 from each other. The non-magnetizable material of the additional layer 8 is copper (Cu).

[0119] An electrical sheet 2 is shown with functional layers 4 having a generally constant thickness (layer thickness) d1i, where i indicates each individual functional layer 4 and extends from 1 to n, where n indicates the total number of functional layers 4 present. Here, d11 = d12 = d13 = ... = d1n, the thickness is generally constant, but varies in width due to the manufacturing process.

[0120] Alternatively, functional layer 4 may be formed with a thickness d1i, which applies to d11 ≠ d12 ≠ d13 ≠ ... ≠ d1n, thus having different thicknesses d1i. Furthermore, only some functional layers 4 may have different thicknesses d1i, while other functional layers 4 may have a substantially constant thickness d1i. The above applies to the thickness d2i of the additional layer 8.

[0121] As can be seen from the scale in Figure 1a, the entire medium achieves layer thicknesses d1i and d2i that are significantly less than 100 µm, and specifically less than 60 µm.

[0122] Figure 1b also shows the structure of the electrical sheet 2 with the aid of a micrograph. The electrical sheet has a functional layer 4 and an additional layer 8 arranged one on top of the other, with the functional layer 4 and the additional layer 8 arranged in an alternating sequence. The functional layer 4 is again composed of steel DD11. In this example, the additional layer 8 is formed as a discontinuous layer, making contact between the functional layers 4 possible. Specifically, in this example, the irregular shapes of the additional layer 8 and the functional layer 4 are clearly visible. Here, the additional layer 8 is made of non-magnetizable aluminum (Al). The ferromagnetic material has a particularly fine-grained structure; the thickness of the functional layer 4 is less than 25 µm, and the thickness of the additional layer is a few µm.

[0123] Figures 1c and 1d show a partial microscopic view of the structure of an electrical sheet 2, which has several functional layers 4 and an additional layer 8 arranged one on top of the other, with the functional layers 4 and the additional layers 8 arranged in an alternating sequence. The functional layers 4 are again composed of steel DD11. In this example, the additional layers 8 are designed to be particularly thin and partially discontinuous, making contact between the functional layers 4 possible at some points. The presence of non-uniform material in the functional layers 4 is also clearly visible here, whereby the different gray levels in the individual functional layers 4 indicate the different compositions of the ferromagnetic material.

[0124] The average thickness of functional layer 4 is less than 75 µm. In the examples shown in Figures 1c and 1d, the non-magnetizable material of additional layer 8 is Worsfield steel (Worsfield body). Additional layer 8 may also appear as a discontinuous layer on the microscope because the thickness of such additional layers is very small at the selected resolution, less than 10 µm or less, but it still allows functional layers 4 to be completely isolated from each other.

[0125] The functional layer 4 and the additional layer 8 of the embodiment of the electrical sheet 2 shown in Figures 1a to 1d are bonded together by an adhesive with atomic diffusion. Specifically, Figure 1b shows the interdiffusion of the different materials of the functional layer 4 and the additional layer 8 at the microscopic level.

[0126] Figures 2a and 2b schematically illustrate the steps of an embodiment of the method according to the present invention for manufacturing electrical sheet 2.

[0127] Figure 2a first shows the process sequence of a cold-rolling plating apparatus 18, in which an electrical strip 2 to be produced is manufactured through various process steps. This electrical strip can be, for example, an electrical strip 2 according to the embodiments shown in Figures 1a to 1d.

[0128] In the first process step 20, the bonding agent is pretreated; here, the pretreatment of the material for the additional layer 8 is shown. In this first process step 20, pre-cleaning 20a, including degreasing the surface, and activation 20b, mechanically tearing the surface, are performed. In the example shown, the material fed from above and below for the functional layer 4 is not activated. However, depending on the material selected for the functional layer 4, additional activation may be provided.

[0129] Furthermore, the layers 4 and 8 to be joined are cold-rolled together, thereby achieving a significant reduction in thickness. The joining of the additional layer 8 of the material with the two functional layers 4 of the material is shown here. The rolling process shown in 20c applies pressure to the layers 4 and 8 to be joined, causing the layers 4 and 8 to come into close contact with each other at the atomic energy level.

[0130] Alternatively, the pretreatment, pre-cleaning, and activation steps shown in process step 20 may be performed on the material of functional layer 4, or only on the material of additional layer 8, and the material of additional layer 8 may be chosen based on the material that has not been pretreated before bonding layers 4 and 8. Therefore, a process may also be provided in which, for process step 20 shown in FIG. 2a, the material of functional layer 4 replaces the material of additional layer 8, and functional layer 4 of the material is pretreated before bonding with additional layer 8 of the material.

[0131] Figure 2b shows an enlarged section of the electrical strip 2 formed by an adhesive bond 12 with atomic diffusion 14. This adhesive bond 12 for the materials of the individual functional layers 4 and the additional layer 8 to be bonded has been initiated in the first process step 20. For some material combinations, this adhesive bond 12 is sufficient for the electrical strip 2.

[0132] According to Figure 2a, other process steps 22 involve adhesion annealing, also known as diffusion annealing, in which heat treatment activates or enhances other rearrangement processes 14 at atomic levels and can transform layers 4 and 8 that are still not fully adhered into bonds. However, for some material combinations, the adhesion generated during plating is sufficient to eliminate the need for adhesion annealing. This is because diffusion bonding is already generated during coating, regardless of whether cold rolling or hot rolling is used.

[0133] Following adhesion annealing, further rolling of the electrical strip 2 occurs in the next step 24, during which it is rolled to almost its final thickness. Additionally, other heat treatments (also known as bell annealing) to adjust the strength and structural properties of the electrical strip 2 can occur in subsequent step 26. Specifically, for very thin final dimensions, process steps 24 and 26 may be performed several times. However, especially for thicker final dimensions, a single rolling / annealing cycle 24, 26 may suffice.

[0134] Figure 2a illustrates other process steps 28, the finishing rolling process, which represents a finishing roll with a lower degree of deformation, in which any tension at the yield point that can occur in the soft-annealed state can be removed from the composite material 32. In this step 28, the target surface finish of the electrical sheet 2 can be set simultaneously by rolling with different roll roughnesses. The final process step 30 shown here is cutting, in which the composite material 32 is cut to its final width.

[0135] Figures 3a and 3b present the test results for various electrical inserts in tabular form, comparing an embodiment of the electrical insert 2 according to the present invention with reference inserts from the prior art, wherein reference inserts R1 and R2 are made of steel DD11. Reference insert R1 is heat-treated at approximately 670°C after production, and reference insert R2 is heat-treated at approximately 1000°C after production.

[0136] In the table of Figure 3a, the material parameters of conductivity ρ, material density ρ, and individual components of the electrical sheets are first given for the embodiments of the electrical sheets E1, E2, Wosten body 1 and Wosten body 2 according to the present invention and for reference object R1. The material parameters of the individual layers are calculated as arithmetic averages.

[0137] Although the reference piece consists of a single functional layer with a sheet thickness of 0.5 mm, electrical sheets E1, E2, Worsfield 1, and Worsfield 2 each consist of 16 layers: eight additional layers, each 10 µm thick; and eight functional layers, each 53 µm thick. The electrical sheet designated E1 has the structure and composition shown in Figure 1a, while electrical sheets E2, Worsfield 1, and Worsfield 2 correspond to Figures 1b, 1c, and 1d, respectively. All listed electrical sheets have a total thickness or sheet thickness of 0.5 mm, as indicated in row 5.

[0138] As described, the functional layer is made of DD11 steel to ensure comparability with references R1 and R2.

[0139] Furthermore, the table in Figure 3a illustrates the reduction in eddy current losses by means of an embodiment of the electrical piece 2 according to the present invention. In row 6 of the table in Figure 3a, the eddy current loss factor kwirbel = φ * d2 / (6 * ρ) calculated for each electrical piece 2 is indicated, based on... The table indicates specific eddy current losses in the materials. Specifically, row 7 of the table shows the reduction in eddy current losses achieved by the electrical sheets E1, E2, Worsfield 1, and Worsfield 2 compared to the reference R1. It is evident that these latter electrical sheets significantly reduce eddy current losses, by an average of 90%. Specifically, this reduction can be attributed to the lower thickness of the individual functional layers, each less than 60 µm.

[0140] The table in Figure 3b compares the hysteresis loss achieved by embodiments of the electrical steel sheets E1, E2, Worsfield 1, and Worsfield 2 according to the present invention with the hysteresis loss achieved by electrical sheets made of reference materials R1 and R2. The table compares specific material quantities, material density ρ, measured coercivity Hc, and hysteresis loss of each electrical sheet measured at frequencies of 1 kHz and 10 kHz.

[0141] Rows 7 and 8 of the table show the reduction in hysteresis loss achieved relative to reference R1 at 1 kHz and relative to reference R2 at 10 kHz using electrical plates E1, E2, Worsfield 1, and Worsfield 2. For each of electrical plates E1, E2, Worsfield 1, and Worsfield 2, a reduction in hysteresis loss is achieved. At 1 kHz, a reduction of at least 14% and at most 34% is achieved, and at 10 kHz, a reduction of at most 1% and at most 43% is achieved.

[0142] To reduce hysteresis loss, it is advantageous to... This is beneficial for reducing coercivity Hc and increasing material density ρ. In this experiment, it was found that by using the electrical sheet 2 of the present invention, which is bonded by an adhesive bond 12 having atomic diffusion 14, and by providing an additional layer 8 according to the present invention, hysteresis loss can be reduced by reducing the coercivity Hc, as shown here for E2, Worsfield 1, and Worsfield 2. Furthermore, even with the increase in coercivity Hc shown here at E1, hysteresis loss can be significantly reduced compared to the reference value, and this reduction is not solely due to the increase in the arithmetic mean of the material density ρ.

[0143] An effect can also be achieved by means of the electrical sheet 2 of the present invention having a functional layer 4 bonded by an adhesive bond 12 having atomic diffusion 14 and an additional layer 8, and by providing an additional layer 8 of the present invention for separating the individual functional layers 4 of the present invention having a small thickness, thereby reducing hysteresis losses caused by the structural processes within the composite material. For example, the energy required to change the alignment of the internal basic structure (magnetic domain) is reduced. This effect can be regarded as an increase in material density, which is effective in electromagnetically related remagnetization effects.

[0144] Figures 4a and 4b illustrate hysteresis measurements of various electrical sheets. Figure 4a compares the hysteresis loops 34 and 36 measured using embodiments E1 and E2 of the electrical sheet 2 according to the present invention, as explained above, with the hysteresis loops 38 and 40 measured using single-layer reference sheets R3 and R4 made of DD11. Reference sheet R3 has been heat-treated at approximately 600°C, while reference sheet R4 is roll-hardened and has not yet undergone heat treatment. Both reference sheets also have a sheet thickness of 0.5 mm.

[0145] In Figure 4b, the hysteresis loops 42 and 44 measured by the embodiments of the electrical sheet 2 according to the present invention, as explained above, are compared with the hysteresis loop 46 measured for the reference sheet R1, as explained above.

[0146] All hysteresis loops 34, 36, 38, 40, 42, 44 and 46 shown in Figures 4a and 4b were measured at a frequency of 1 kHz.

[0147] Hysteresis loss is proportional to the area of ​​each hysteresis loop traversed, such that it can be seen from the figures that, compared with the reference electrical pieces R1, R3 and R4, the hysteresis loss measured in the respective figures of the embodiments of electrical pieces E1, E2, Worsfield 1 and Worsfield 2 according to the present invention is lower.

[0148] Specifically, compared to all other measured values, the measured hysteresis loss for E2, with a value of Physt = 1647 W / kg, is significantly reduced. The measured hysteresis losses for E1 (Physt = 2280 W / kg), for Worsfield 1 (Physt = 2121 W / kg), and for Worsfield 2 (Physt = 2131 W / kg) are also lower than those for reference material R1 (Physt = 2556 W / kg), for R3 (Physt = 2436 W / kg), and for R4 (Physt = 2732 W / kg).

[0149] All the measurements presented clearly demonstrate that the electrical sheet 2 according to the embodiments of the invention described above achieves a reduction in both hysteresis loss and eddy current loss. Overall, when the electrical sheet 2 according to the invention is used in an electromagnetic assembly, core magnetization loss is significantly reduced, both by the targeted material selection of the functional layer 4 and the additional layer 8 and by the design of the targeted materials, specifically by the thickness of the functional layer 4. This achieves optimized energy conversion in the electromagnetic assembly and allows for more flexible design of the electromagnetic assembly, specifically through variable and combinable layer thicknesses and variable material selection.

[0150] The absolute values ​​of the hysteresis curves shown in Figures 4a and 4b should be understood as examples. If steels with different ferromagnetic properties are used as reference materials and functional layers of the electrical sheet according to the present invention, other absolute magnetization values ​​can be produced, but the relative orientation of the hysteresis curves and the interpreted improvements will occur in the same manner as with other steels.

[0151] 2: Electrical film 4: Functional Layer 8: Additional Layer 12: Adhesive bonding 14: Atomic diffusion 18: Cold Rolling Coating Equipment 20, 22, 28, 30: Process steps 20a: Pre-cleaning 20b: Activation 24: Process Steps / Rolling 26: Process Steps / Annealing 34, 36, 38, 40, 42, 44, 46: Hysteresis loops d 11 , d 12 , d 13 , d 21 , d 22 : thickness E1, E2: Electrical components R1, R2, R3, R4: Reference films

Claims

1. An electrical strip having at least one functional layer (4) at least partially composed of a ferromagnetic material, and having at least one additional layer (8) at least partially composed of a nonmagnetizable material, characterized in that the at least one functional layer (4) and the at least one additional layer (8) are bonded to each other by an adhesive (12) having atomic diffusion (14).

2. An electrical strip having at least one functional layer (4) at least partially composed of a ferromagnetic material, and having at least one additional layer (8) at least partially composed of a nonmagnetizable material, wherein the at least one additional layer (8) and the at least one functional layer (4) are bonded to each other, characterized in that the thickness of the at least one functional layer (4) is in the range of 2 to 100 µm.

3. The electrical strip of claim 2, characterized in that the at least one additional layer (8) and the at least one functional layer (4) are bonded to each other by an adhesive bond (12) having atomic diffusion (14).

4. The electrical strip of any one of claims 1 to 3, characterized in that the thickness of the at least one additional layer (8) is in the range of 2 to 100 µm.

5. The electrical strip of any one of claims 1 to 3, characterized in that the at least one additional layer (8) is at least partially composed of a metallic material.

6. The electrical strip of any one of claims 1 to 3, characterized in that the at least one additional layer (8) has copper (Cu).

7. The electrical strip of any one of claims 1 to 3, characterized in that the at least one additional layer (8) has aluminum (Al).

8. An electrical strip of any one of claims 1 to 3, characterized in that the at least one additional layer (8) has a specific thermal conductivity at least equal to that of the at least one functional layer (4).

9. The electrical strip of any one of claims 1 to 3, characterized in that the at least one additional layer (8) is at least partially composed of a Worsfield alloy or a Worsfield steel.

10. The electrical strip of any one of claims 1 to 3, characterized in that the at least one additional layer (8) is at least partially composed of a non-metallic material.

11. An electrical strip of any one of claims 1 to 3, characterized in that at least two functional layers (4) have different ferromagnetic materials, and / or when several additional layers (8) are used, at least two additional layers (8) have different nonmagnetizable materials.

12. An electrical strip as claimed in any one of claims 1 to 3, characterized in that the material properties vary in the at least one functional layer and / or the at least one additional layer.

13. An electrical strip, specifically an electrical sheet, configuration as claimed in any one of claims 1 to 12, characterized in that at least two electrical strips are arranged in a stack, and a separation layer is disposed between the at least two electrical strips.

14. An application of an electrical strip as claimed in any one of claims 1 to 12, which serves as an iron core.

15. A method of manufacturing an electrical strip as claimed in any one of claims 1 to 12, wherein at least one functional layer (4) is provided, wherein at least one additional layer (8) is provided, wherein the at least one functional layer (8) and the at least one additional layer are disposed adjacent to each other, and wherein an adhesive bond (12) having atomic diffusion (14) is generated between the at least one functional layer (4) and the at least one additional layer (8) by applying pressure.

16. The method of claim 15, wherein at least one of the at least one functional layer (4) and / or at least one of the at least one additional layer (8) is heat-treated.

17. The method of claim 15 or 16, wherein the at least one functional layer (4) and the at least one additional layer (8) are joined together by means of cold rolling or by means of hot rolling.

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