Method for manufacturing a laminated core for an electrical machine - Patent Application 20070122997

Abstract

A method for manufacturing a laminated core (1) for an electric machine, comprising the steps of: a) providing a foil sheet (4) each comprising an aluminum support foil (6) and a natural or produced aluminum oxide layer (7) and each coated on at least one side (11, 12) on a flux barrier surface (8) with a first foil coating (10) of a first powder mixture, the first powder mixture comprising an austenite stabilizer, aluminum oxide and an adhesive binder; b) providing metal sheets (5) of a laminated core (1); c) stacking the metal sheets (5) and the foil sheets (4) alternately, the orientation of the foil sheets (4) relative to the metal sheets (5) being such that the magnetic flux barrier surface (8) of each foil sheet (4) is in direct contact with each metal sheet (5) at a specific magnetic flux barrier point (9) of each metal sheet (5); and d) heating the stack of metal sheets (5) and foil sheets (4), austenite stabilizer from the first foil coating (10) of the foil sheet (4) diffuses into the metal of the respective contacting metal sheet (5) at the respective flux barrier points (9) to form a flux barrier (15); and - with dissolution of the support foil (6), aluminium from the support foil (6) of the foil sheet (4) diffuses into the metal of the respective adjacent metal sheet (5).

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a laminated core for an electrical machine. [Background technology]

[0002] EP 3511429 A1 discloses a laminated core and a method for producing the laminated core. Here, a metal plate layer is coated with a coating containing at least 20% aluminum and / or silicon by mass. The coated starting laminated core is then heat-treated to produce a laminated core. In one embodiment, the produced laminated core can have a silicon content of at least 6.5% by mass. In another embodiment, the silicon content can be greater than 4% and less than 6.5% by mass. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] European Patent Application Publication No. 3511429 Summary of the Invention [Means for solving the problem]

[0004] The method according to the invention with the features of the independent claims has the advantage that it allows for the targeted localization of flux barriers in the metal laminations of the laminated core. This makes it possible to modify the material properties of the rotor webs to make them magnetically non-conductive and thereby to create the flux barriers. In particular, the lamination structure of the laminated core allows for the creation of flux barriers with a three-dimensional shape.

[0005] According to the invention, this is achieved by the following method steps: In a first step 1a), a foil sheet is provided, each comprising an aluminum support foil and a natural or produced aluminum oxide layer, each coated on at least one side, on the flux barrier side, with a first foil coating of a first powder mixture, the first powder mixture comprising an austenite stabilizer or eutectic former, in particular manganese and / or nickel and / or cobalt, an electrical insulator, in particular aluminum oxide or silicon oxide (SiO2), and an adhesive binder, where the first foil coating forms a flux barrier after a subsequent heat treatment.

[0006] In a subsequent second step 1b), the sheet metal sheets of the laminated core are provided, which are in particular not electrically insulating, ie do not have a paint coating. In a subsequent third step 1c), the metal sheets and the foil sheets are stacked alternately, and the foil sheets are oriented relative to the metal sheets, particularly with respect to the rotational position, so that the magnetic flux barrier surface of each foil sheet is in direct contact with each respective metal sheet at a specific magnetic flux barrier point of each metal sheet.

[0007] In the subsequent fourth step 1d), the heating, in particular the heat treatment, of the stack of metal sheets and foil sheets is carried out as follows. - the austenite stabilizer from the first foil coating of the foil laminate diffuses into the metal of the respective contacting metal laminate at the respective flux barrier point, forming a flux barrier; As the support foil melts, aluminum from the support foil of the foil sheet diffuses into the metal of the adjacent sheet metal, whereby the aluminum content between the surface and the core of the sheet metal may decrease.

[0008] In this way, a non-magnetic austenite phase is formed at the magnetic flux barrier points. Advantageous developments of the method presented in the independent claims are possible by the measures set out in the dependent claims.

[0009] Advantageously, the first powder mixture further comprises an electrically insulating insulator material, in particular aluminum oxide or silicon oxide (SiO2), and / or an alloying material, in particular silicon, since this simultaneously results in an insulating layer between adjacent metal sheets in the region of the magnetic flux barrier surface of each foil sheet and / or further alloying of adjacent metal sheets in the region of the magnetic flux barrier surface.

[0010] Advantageously, in step 1a), each foil sheet is coated on its insulating side with at least one second foil coating of a second powder mixture, each containing an electrically insulating insulator, in particular aluminum oxide or silicon oxide (SiO2), and an adhesive binder. In this way, preparations are made for the creation of a complete insulating layer between adjacent, in particular non-insulated, metal sheets.

[0011] It is highly advantageous if heating is performed in step 1d) such that insulating material, in particular from the first and / or second foil coating of the foil laminate and / or from the aluminum oxide layer, remains between the metal laminates after heating, forming insulating layers between adjacent metal laminates, respectively, in the region of the insulating surfaces and in particular in the region of the magnetic flux barrier surfaces or magnetic flux barriers. This generation of insulating layers between adjacent metal laminates allows the utilization of the generated magnetic flux barrier in the laminated core.

[0012] Additionally, an adhesive binder is provided to adhere the first or second powder mixture to the support foil of each foil sheet, and is advantageously a paste and / or a polysaccharide, especially xanthan and / or amylopectin. For example, to ensure a secure bond of the powder to the foil sheet, aluminum oxide powder or a powder mixture consisting of manganese powder and aluminum oxide powder can be mixed with water and xanthan. This mixture can then be coated on at least one side of the foil sheet, for example, using a compressed air spray gun. A suitable stencil can then be used to adequately cover a portion of each metal sheet, so that only the areas that will later serve as magnetic flux barriers are coated during coating with the manganese-containing powder mixture. In the case of a manganese-free powder mixture, a stencil that covers only the magnetic flux barrier areas is preferably used. During subsequent drying, the water evaporates. The xanthan remaining in the mixture ensures good adhesion of the powder. The other side of the foil sheet can then be coated in the same way.

[0013] According to an exemplary embodiment, the shape and / or area of ​​the foil sheets correspond to those of the sheet metal sheets. The foil sheets can be punched to the same shape as the sheet metal sheets before being stacked on the laminated core. Preferably, however, the laminated core is formed by alternately stacking non-punched foil sheets and punched sheet metal sheets, and after stacking is complete, the excess aluminum foil is removed. Since the aluminum foil is very thin, little waste is required. In another possible embodiment, the removal of the excess foil can be omitted, as it melts and drips off during the heat treatment.

[0014] Furthermore, it is advantageous if the first powder mixture comprises a further substance suitable for forming a eutectic with the austenite stabilizer, in particular with a melting point below 1300° C. Since nickel does not form a eutectic with iron, in order to form a eutectic with the austenite stabilizer, tin in particular is provided to form a eutectic with nickel.

[0015] The eutectic formers are advantageously capable of promoting the formation of austenite from the liquid phase down to low temperatures, without decomposition into two phases on further cooling, so that austenite is present even at room temperature. The eutectic formers are based on copper and / or zinc and / or carbon and / or nitrogen.

[0016] During heat treatment, the austenite stabilizer diffuses into the iron, resulting in austenite rather than other transformations, particularly ferrite. In this case, a high concentration can be achieved locally, with the austenite stabilizer diffusing to some extent from two sides of each sheet metal to the core. By adding additional eutectic-forming substances, such as manganese, nickel, or cobalt, or a mixture of these austenite stabilizers, a lower melting point can be advantageously achieved. It is also conceivable to use only the eutectic-forming substances copper and / or zinc and / or carbon and / or nitrogen to induce the formation of austenite. However, carbon has the disadvantage of being very diffusive, while nitrogen has the disadvantage of being very poorly diffusive.

[0017] Advantageously, a multi-step heat treatment in the presence of hydrogen can be contemplated. Advantageously, prior to this heat treatment, a further heat treatment of the metal sheets between which the coated foil sheets are placed is carried out at a temperature ranging from about 150°C to about 500°C for about 1 to about 2 hours. This can be carried out at 400°C in particular. In this first step, the xanthan is decomposed into water, carbon monoxide, carbon dioxide, and methane, and can therefore be removed. In the next step, heat treatment is carried out at a temperature ranging from 950°C to 1250°C, preferably from 1000°C to 1100°C, for a period of 1 to 24 hours, in particular, to diffuse an austenite stabilizer, particularly manganese and aluminum, into the metal sheets. Once the austenite stabilizer and aluminum have been completely diffused, an electrically insulating solid, such as aluminum oxide powder, remains between the metal sheets as an electrically insulating layer.

[0018] In one possible embodiment, laminated cores can be inexpensively manufactured, particularly with inherent magnetic flux barriers and excellent electrical insulation between the individual metal sheets. Advantageously, the formation of local inherent magnetic flux barriers within the metal sheets can be achieved by at least one austenite stabilizer dispersed within the metal sheets. Preferably, the local inherent magnetic flux barriers extend across the thickness of each metal sheet. The inherent magnetic flux barriers are created by locally losing the ferromagnetic properties of each metal sheet, and therefore also losing or at least substantially reducing its very high magnetic permeability. Furthermore, electrical insulation between the metal sheets can be ensured at the same time.

[0019] Thus, the magnetic flux barrier is realized by omitting the electrical sheet, which, unlike conventional designs in which slots are provided or the thickness is locally reduced by embossing, improves the mechanical stability of the metal sheet. In particular, this allows for higher maximum speeds, especially for the rotor, and improves the vibration resistance of the laminated core. Furthermore, advantageously, the configuration of the magnetic flux circuit can be improved, in particular allowing for a more flexible configuration without requiring significant manufacturing costs.

[0020] Thus, the austenite stabilizer advantageously allows for the realization of paramagnetic austenite, thus avoiding the formation of ferromagnetic and therefore highly permeable ferrite. In the regions where the austenite stabilizer is diffused, the paramagnetic austenite is stable up to room temperature.

[0021] The powdered austenite stabilizer can advantageously be part of a powder mixture with an insulating solid (especially silicon dioxide) and, optionally, an additional substance (especially silicon) as an alloying material. The coated aluminum foil is preferably cut into foil sheets large enough to completely cover each individual metal sheet. When stacking metal sheets for rotor or stator electrical sheets, preferably, one foil piece is placed for each metal sheet placed in the stack. The stack thus formed advantageously consists of alternating metal sheets and foil sheets. During subsequent heat treatment, the austenite stabilizer or silicon or aluminum in the aluminum foil is diffused depending on the presence in one region, and the electrically insulating powder remains as an electrically insulating layer between adjacent metal sheets.

[0022] In one possible embodiment, aluminum foil is coated with at least two different powder mixtures, both containing inorganic electrical insulator powders. At least one of the powder mixtures preferably contains at least one austenite stabilizer. The coated aluminum foils can then be stacked alternately with metal sheets to form a laminated core. A heat treatment then follows, diffusing the aluminum and austenite stabilizer into the metal sheets. The insulating powder remains between adjacent metal sheets as an electrically insulating layer. Coating can be achieved by methods such as spraying, brushing, or printing.

[0023] Suitable austenite stabilizers are preferably those that strongly promote the formation of austenite when cooled from temperatures above 1200°C. Additional requirements may be that such austenite stabilizers are stable in a hydrogen atmosphere and diffuse into the iron of the sheet metal at least at 1200°C. Manganese, nickel, and cobalt are particularly preferred, but copper is also preferred. Copper forms a eutectic down to low temperatures, at which austenite can no longer be decomposed into other phases. Furthermore, it is advantageous to apply the austenite stabilizer together with additional substances, particularly those with melting points below 1300°C, that do not participate in the formation of ferrite or austenite but form a eutectic with the austenite stabilizer. Such additional substances may also be austenite stabilizers, but less effectively.

[0024] Materials suitable for the electrically insulating powder are electrically insulating solids that are stable and do not melt, preferably in a water atmosphere up to at least 1250°C. In a hydrogen atmosphere, a significant reduction in aluminum oxide by up to 20% by mass fraction occurs only at 1300°C. At a heat treatment temperature of 1250°C, the aluminum oxide is reduced by up to 7%. Silicon oxide (SiO2) and mullite (Al (4+2x) Si (2-2x) O (10-x) , where x=0.17 to x=0.59), are also stable and do not melt in strongly reducing aqueous atmospheres up to 1250°C, and therefore are similarly suitable as electrically insulating solids.

[0025] For example, an aluminum foil may have a thickness of 5 μm and be print-coated on both sides with a mixture of manganese powder and aluminum oxide powder, or with aluminum oxide powder alone, depending on the desired flux barrier geometry. The manganese powder may consist of manganese nanopowder with a particle size of approximately 30-50 nm and / or manganese powder with an average particle size of 1-5 μm. The aluminum oxide powder may have an average particle size of, for example, 3 μm or even 40 nm. However, depending on the application and availability, other particle sizes may be used for the manganese powder or manganese nanopowder and aluminum oxide powder. The same applies to other materials.

[0026] Thus, laminated cores with advantageous properties can be realized at low cost, which in particular allows for the economical realization of very powerful electric motors, which are used, for example, in electric cars, electric bicycles or hybrid drives.

[0027] Preferred exemplary embodiments of the present invention are described in more detail herein below with reference to the accompanying drawings, in which corresponding elements are designated with the same reference numerals, and in which: [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 2 is a schematic diagram of a laminated core before heat treatment. [Figure 2A] 2 is a partial view of the laminated core according to FIG. 1 according to detail II in FIG. 1; [Figure 2B] 2 is a partial view of the laminated core according to FIG. 1 after heat treatment according to detail II in FIG. 1; [Figure 3] 2C is a partial view of the laminated core corresponding to the viewing direction III in FIG. 2B. [Figure 4A] 1 is a phase diagram illustrating the present invention, showing a diagram for an austenite stabilizer; FIG. [Figure 4B] 1 is a phase diagram illustrating the present invention, showing a diagram for eutectic formers; FIG. [Figure 4C]1 is a phase diagram illustrating the present invention, showing a diagram for ferrite forming materials; DETAILED DESCRIPTION OF THE INVENTION

[0029] FIG. 1 shows a schematic diagram of a laminated core 1 before heat treatment. FIG. 2A shows a partial view of the laminated core according to FIG. 1 according to detail II in FIG. FIG. 2B is a partial view of the laminated core according to FIG. 1 after heat treatment according to detail II in FIG.

[0030] The laminated core 1 includes a plurality of thin metal plates 5 made of an iron-based material stacked on top of each other. FIG. 1 shows the state of the laminated core 1 before heat treatment. The laminated core 1 may be a laminated core for a rotor or a stator of an electric machine. The laminated core 1 is formed into a cylindrical shape.

[0031] 2A and 2B show in schematic and partial views the laminated core 1 before and after heat treatment according to possible forms. To manufacture the laminated core 1, the following method steps are carried out according to the invention.

[0032] In a first step 1a), a foil sheet 4 is provided, each comprising an aluminum support foil 6, i.e., aluminum foil 6, and a natural or produced aluminum oxide layer 7, each coated on at least one side 11, 12, on a flux barrier surface 8, with a first foil coating 10 of a first powder mixture, the first powder mixture comprising an austenite stabilizer, in particular manganese and / or nickel and / or cobalt, aluminum oxide, and an adhesive binder.

[0033] In a second step 1b), metal sheets 5 of the laminated core 1 are provided, which are in particular not electrically insulated. The metal sheets 5 are made from electrical sheets. The shape and / or area of ​​the foil sheets 4 can correspond to the shape and / or area of ​​the metal sheets 5.

[0034] In a third step 1c), the metal sheets 5 and the foil sheets 4 are stacked alternately, and the foil sheets 4 are oriented relative to the metal sheets 5 such that the magnetic flux barrier surface 8 of each foil sheet 4 is in direct contact with each metal sheet 5 at a specific magnetic flux barrier point 9 of each metal sheet 5.

[0035] In a fourth step 1d), the stack of metal sheets 5 and foil sheets 4 is heated, for example by heat treatment in an oven. According to the invention, the heating is carried out as follows: - the austenite stabilizer from the first foil coating 10 of the foil sheet 4 diffuses into the metal of the respective contacting metal sheet 5 at the respective flux barrier points 9, forming a flux barrier 15 in the metal sheet 5; With the melting of the support foil 6, the aluminum from the support foil 6 of the foil lamina 4 diffuses to a certain depth into the metal of the respective adjacent metal lamina 5.

[0036] The first powder mixture may further comprise an electrically insulating insulator material, in particular aluminum oxide or silicon oxide (SiO2), and / or an alloy material, in particular silicon. Furthermore, in step 1a), each foil sheet 4 is further coated on its coated side 11, 12, respectively, on its insulating side 16, on which magnetic flux is retained, with at least one second foil coating 20 of a second powder mixture, each of which may comprise an electrically insulating insulating material, in particular aluminum oxide or silicon oxide (SiO2), and an adhesive binder. Heating is then carried out in step 1d), and insulating material, in particular from the first and / or second foil coating 20 of the foil sheet 4 and / or from the aluminum oxide layer 7, remains between the metal sheets 5 after heating is completed, forming insulating layers 32 between adjacent metal sheets 5, respectively, wherein each insulating layer 32 may be formed in the region of the insulating side 16, more particularly in the region of the magnetic flux barrier surface 8 or the magnetic flux barrier 15.

[0037] The adhesive binder of the first and second powder mixtures is used to adhere the first or second powder mixture to the support foil 6 of the respective foil sheet 4 and may be, for example, a paste and / or a polysaccharide, in particular xanthan.

[0038] Several exemplary embodiments of the present invention are described below. Prior to the heat treatment, aluminum-based foil sheets 4, which can be cut from aluminum foil, are inserted between the stacked metal sheets 5. The aluminum foil from which the foil sheets 4 are made is provided or coated, for example, on both sides with a natural or produced aluminum oxide layer 7. Here, the aluminum oxide layer 7 is formed continuously. Furthermore, both sides are provided with at least one first coating 10 containing an austenite stabilizer, which is only partially applied. In this exemplary embodiment, the foil sheet 4 has upper surfaces 11, 12 to which the first coating 10 containing an austenite stabilizer is applied. Furthermore, a second coating 20, which may contain, for example, a silicon-based alloy material, is applied to the areas where the first coating 10 is not applied.

[0039] Between adjacent metal sheet laminates 5 of the laminated core 1, foil laminates 4 are arranged, each having at least one aluminum oxide layer 7. Furthermore, a first coating 10, which contains, for example, manganese as an austenite stabilizer, is applied to the foil laminates 4. Where manganese is not applied to each foil piece 4, a second coating 20, which contains silicon as an alloying material, can be applied.

[0040] A respective first foil coating 10 is applied to the foil sheet 4 and each foil sheet 4 is placed between two metal sheet sheets 5 of the laminated core 1, so that austenite stabilizers and / or eutectic formers and / or formers of eutectic with austenite formers can be diffused into the material of each metal sheet 5 at the flux barrier points 9 of each metal sheet 5 by heat treatment.

[0041] After the heat treatment, the metal sheets 5 may have areas where manganese has been diffused, areas where silicon and aluminum have been diffused, and an aluminum oxide layer 32 remaining between the metal sheets 5 . As shown in FIG. 2B , after heat treatment, an insulating layer 32 remains between the metal sheets 5. Here, the insulating layer 32 is obtained from the electrically insulating solid remaining between the metal sheets 5. The aluminum of the support foil 6 of the foil sheet 4 diffuses into the metal sheets 5 along with the silicon, creating an average penetration depth in each metal sheet 5. This results in the metal sheets 5 containing ferroalloy or high-ferroalloy material at least near the surface. The austenite stabilizer from the first coating 10 also diffuses into the metal sheets 5, with some diffusion from additional foil sheets 4 (not shown) occurring on both sides. The appropriate concentration of austenite stabilizer creates magnetic flux barriers 15 within the metal sheets 5 across the entire thickness 33 of the metal sheets 5 and magnetic flux barriers 14 within adjacent metal sheets 5.

[0042] The austenite stabilizer of the first coating 10 is based on manganese and / or nickel and / or cobalt and / or copper. Preferably, additional substances can be used that form a eutectic to lower the melting point, but also promote or have little effect on austenite formation. These substances, particularly the electrically insulating solid and the austenite stabilizer, are preferably in powder form and applied to the upper surfaces 11, 12 of the foil sheet 4 with an adhesive, particularly an adhesive binder and / or a polysaccharide, especially xanthan or amylopectin. Separation into individual layers, as shown in FIG. 1, is not necessarily required. This means that, on the one hand, the alloy material, particularly silicon, can be mixed with the electrically insulating solid and then applied partially to the upper surfaces 11, 12 of the foil sheet 4 with the adhesive binder and / or polysaccharide. On the other hand, the austenite stabilizer can be mixed with the electrically insulating solid and then applied to the remaining portions. Other orders are also possible.

[0043] FIG. 3 is a partial view of the laminated core corresponding to the viewing direction III in FIG. 2B. The austenite stabilizer is applied to the foil sheets 4 so as to form flux barriers 15 at the flux barrier points 9 in each metal sheet 5. In this exemplary embodiment, the flux barriers 15 are configured in or on webs 16 of the metal sheet 5. The webs 16 are formed, for example, by recesses 22 in each metal sheet 5. The recesses 22 may be provided, for example, near the circumference 21 of the laminated core 1.

[0044] Thus, for example, specific local magnetic flux barriers 15 can be formed within the metal sheet 5. These magnetic flux barriers 15 allow for substantial improvements in form and functionality. 4A, 4B, and 4C, the effect of a suitable alloying element X on the size of each austenite domain is shown in each phase diagram of FeX, where the concentration (wt%) of each alloying element X is plotted on the x-axis and the temperature T is plotted on the y-axis.

[0045] 4A is a phase diagram illustrating the present invention, showing an austenite stabilizer diagram. With manganese as an austenite stabilizer, the austenite phase (γ) becomes stable at lower temperatures as the manganese concentration increases, as shown in the schematic phase diagram. In this diagram, room temperature is shown as the lower temperature limit.

[0046] 4A shows an exemplary behavior according to the invention according to line Y, illustrating the effect of austenite stabilization during the course of heat treatment. Due to the diffusion of the austenite stabilizer into the respective metal sheet 5, the austenite of the heated metal sheet 5 is stabilized so that, upon cooling of the metal sheet 5, the austenite does not transform back into ferrite according to the phase diagram.

[0047] FIG. 4B shows a phase diagram for explaining the present invention, showing a diagram for eutectic forming materials. As shown in the schematic phase diagram, with copper as a eutectic former, the austenite phase becomes stable at lower temperatures as the copper concentration increases. However, this does not allow stability down to room temperature. At a certain copper concentration, a minimum temperature value occurs at which the austenite phase is still stable. This region, where austenite is stable even at temperatures significantly lower than A3, allows the austenite to be nearly frozen upon cooling and thus preserved upon further cooling to room temperature. As the copper concentration increases further, the temperature at which the austenite phase becomes stable also increases. This makes it increasingly difficult, and eventually impossible, to nearly freeze austenite upon cooling. Further increases in copper concentration lead to a concentration at which the formation of the austenite phase in iron is no longer possible.

[0048] FIG. 4C is a phase diagram for explaining the present invention, showing a diagram relating to ferrite forming materials. As shown in the schematic phase diagram, ferrite (α) is the stable phase at room temperature due to the presence of ferrite formers such as silicon and aluminum. This means that austenite is stable only when low concentrations of ferrite formers are present at the same time as high temperatures. Therefore, austenite cannot freeze out on cooling, as it will transform to ferrite at higher temperatures.

[0049] The invention is not limited to the exemplary embodiments described above.

Claims

1. A method for manufacturing a laminated core (1) of an electric machine, in particular for creating a magnetic flux barrier within said laminated core (1), comprising: a) providing a foil sheet (4), each comprising an aluminum support foil (6) and a natural or produced aluminum oxide layer (7), each coated on at least one side (11, 12) with a first foil coating (10) of a first powder mixture on a magnetic flux barrier surface (8), said first powder mixture comprising an austenite stabilizer, in particular manganese and / or nickel and / or cobalt, aluminum oxide, and an adhesive binder; b) providing the metal sheets (5) of the laminated core (1), said metal sheets (5) being not particularly electrically insulating; c) stacking metal sheets (5) and foil sheets (4) alternately, the foil sheets (4) being oriented relative to the metal sheets (5) such that the magnetic flux barrier surface (8) of each foil sheet (4) is in direct contact with each metal sheet (5) at a specific magnetic flux barrier point (9) of each metal sheet (5); d) heating, in particular heat treating, the laminate of metal sheets (5) and foil sheets (4), - the austenite stabilizer from the first foil coating (10) of the foil laminate (4) diffuses into the metal of the metal sheet laminate (5) that it contacts at each of the magnetic flux barrier points (9) to form a magnetic flux barrier (15); - with the dissolution of the support foil (6), the aluminum from the support foil (6) of the foil laminae (4) diffuses into the metal of the respective adjacent metal laminae (5); method.

2. The first powder mixture may further comprise an electrically insulating insulating material, in particular aluminum oxide or silicon oxide (SiO ２ 2. The method according to claim 1, characterized in that the material contains a metal, and / or an alloy material, in particular silicon.

3. In step a), the foil sheets (4) are each further coated on the coated side (11, 12), respectively on the insulating side (16), with at least one second foil coating (20) of a second powder mixture, the second powder mixture being each an electrically insulating insulator material, in particular aluminum oxide or silicon oxide (SiO ２ 10. The method of claim 1, further comprising:

4. 4. The method according to claim 3, characterized in that the heating in step d) is carried out so that the insulating material, in particular from the first and / or second foil coating (20) of the foil laminations (4) and / or from the aluminum oxide layer (7), remains between the metal laminations (5) after the heating, forming insulating layers (32) between adjacent metal laminations (5), respectively, the insulating layers (32) being formed in the region of the insulating surface (16) and in particular in the region of the magnetic flux barrier surface (8) or the magnetic flux barrier (15).

5. 2. The method according to claim 1, characterized in that the adhesive binder is provided to adhere the first or second powder mixture to the support foil (6) of the respective foil sheet (4), and is in particular a paste and / or a polysaccharide, in particular xanthan and / or amylopectin.

6. 2. The method according to claim 1, wherein the shape and / or area of ​​the foil sheet (4) corresponds to the shape and / or area of ​​the metal sheet (5).

7. 2. The method according to claim 1, wherein the first powder mixture comprises a further substance suitable for forming a eutectic with the austenite stabilizer, in particular with a melting point below 1300°C.

8. 2. The method of claim 1, wherein the heat treatment is preceded by a further heat treatment of the metal sheet laminates (5) between which the coated foil laminates (4) are arranged in a hydrogen-containing atmosphere at a temperature in the range of about 150°C to about 500°C for about 1 hour to about 2 hours in order to decompose the adhesive binder of the first and / or second foil coating (10, 20).

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