EP2483898B1 - Transformer core or transformer sheet having an amorphous and/or nanocrystalline microstructure and method for the production thereof - Google Patents

Description

The invention relates to a transformer core, comprising soft magnetic layers of an electrically conductive core material having an amorphous and / or nanocrystalline microstructure, which are separated from one another by separating layers of an electrically insulating material. Furthermore, the invention relates to a transformer sheet, comprising a soft magnetic layer of an electrically conductive core material having an amorphous and / or nanocrystalline microstructure, which is coated with a release layer of an electrically insulating material.

Moreover, the invention also relates to a method for producing a transformer sheet or a transformer core.

A transformer core or transformer sheet of the type specified and a method for its production is, for example, in the DE 33 26 556 C2 described. Thereafter, a transformer sheet having an amorphous microstructure can be obtained, for example, by dropping the molten metal containing a glass-forming element onto a cooled substrate, thereby causing extremely rapid cooling of the dropped metal. As a result, the metal solidifies amorphous. Subsequently, the electrically insulating layer can be applied by electrochemical means by a cathodic electrodeposition. The resulting transformer sheets can be processed by laminating or winding into a transformer core in which the layer of the metal with the amorphous crystal structure alternate with the separation layers.
According to the WO 2008/092265 A1 It is also known that amorphous self-supporting films can be produced by electrochemical means, which have a thickness between 20 and 250 microns. In this case, an alloy is deposited, which has iron as the main part, as a glass former phosphorus and another transition metal as alloying shares. FR 2 842 018 A3 . DE 33 46 659 A1 and the article " Solenoid-Type Thin-Film Micro-Transformer "by H. Kurata et al., IEEE Translation Journal on Magnetics, Japan, Vol. 9, No. 3, 1994 ) disclose transformers in which the magnetic core is formed of amorphous magnetic layers and insulating separation layers in monolithic composite with the transformer windings. US 5 435 903 A shows a transformer core, which is produced by the deposition of amorphous soft magnetic layers and electrically insulating separation layers.

Due to the relatively small thickness of the amorphous transformer sheets thus produced and their brittle behavior, the layering of such transformer sheets to transformer cores is associated with considerable expense. The object of the invention is therefore to provide transformer cores and transformer sheets and a method for their production, with which the production of transformer cores is comparatively facilitated.
This object is achieved with the transformer core specified above according to the invention in that a plurality of said soft magnetic layers and at least separating layers lying between them form a monolithic composite. A monolithic composite in the sense of the invention thus means an intimately interconnected layer sequence which has at least two soft magnetic layers and at least one separating layer therebetween. Of course, the composite may also have more than these three layers. Preferably as many separating layers as soft magnetic layers are arranged in the composite, so that several of these compounds can be stacked and in each case the uppermost separating layer of a composite with the lowest soft magnetic layer of the subsequent composite comes into contact. This is also at the transition between two connected ensures the electrical insulation of adjacent soft magnetic layers. According to the invention, the individual composites can also be processed as transformer sheets, with a plurality of said soft magnetic layers forming a monolithic composite at least with the separating layers lying between them. Again, it is particularly advantageous if just as many soft magnetic layers are produced as separating layers.
According to the invention, the monolithic composites are produced by the aforementioned method for producing a transformer sheet or a transformer core, in which a soft magnetic layer of an electrically conductive core material with an amorphous and / or nanocrystalline microstructure is electrochemically deposited on a base body. An electrically insulating separating layer is produced on the soft magnetic layer. Then a starting layer for a renewed electrochemical coating is then produced, then a further soft magnetic layer after the already mentioned method step and a further separating layer after the likewise described method step. This is repeated until the transformer sheet has reached the intended thickness. A composite is thus produced by the sequence of electrochemical coating steps, so that the layers grow on each other and thus creates an intimate connection. Therefore, in the required small thickness of the individual soft magnetic layers by producing the composite, a transformer sheet can be produced which has a sufficient thickness for the further handling steps. This facilitates the manufacture of transformer cores themselves, as the brittle material is easier to handle when it is in a greater thickness. In addition, the layers of as Composite manufactured transformer sheets simplified because fewer of these thicker transformer sheets must be laminated to the transformer core.
The advantage of using amorphous transformer cores or transformer plates is that they advantageously produce only small losses when used in the transformer. This is due to the low coercive field strength H _C , so that hysteresis losses during remagnetization can be kept low. In the case of an amorphous structure of the soft-magnetic layers, it is not possible to detect formation of structure grains. This is because the glass-forming alloying portion results in a vitreous structure, so that the order of the atoms is stochastic like a liquid. In the case of a nanocrystalline microstructure, individual grains can be recognized whose size, however, is in the nanometer range, ie smaller than 100 nm, preferably even smaller than 10 nm. The transition between an amorphous and nanocrystalline structure of the microstructure is fluid, although crystalline regions of the microstructure with dimensions in the nanometer range may also be present within an amorphous matrix surrounding them.
According to one embodiment of the invention, it is provided that the transformer core or the transformer sheet (or the sheets in a layered transformer core) have soft magnetic layers whose thickness is between 2 and 100 μm. In this way, it can be advantageously effected that the separating layers follow one another rapidly in the sequence of layers, which advantageously results in the eddy current losses in the transformer sheet minimize. The formation of eddy currents is namely prevented by the electrically insulating separation layers or at least contained. The separating layers can advantageously have a thickness of 0.1 to 1 μm. This thickness is sufficient to achieve sufficient electrical insulation between the adjacent soft magnetic layers. The monolithic layer composites produced can advantageously have a thickness between 0.2 and 0.6 mm. This thickness is sufficient for the composites to have sufficient handling stability during the stacking of the transformer core from individual transformer laminations.

According to another embodiment of the invention, it is provided that in the transformer sheet or the transformer core, the separating layers and / or the starting layers lying between the separating layers and the soft magnetic layers are doped with nanoparticles for electrochemical deposition, like the relevant layer into which they are incorporated are electrically conductive or electrically insulating. The chemical elements that make up the nanoparticles are selected in such a way that their incorporation into the matrix of the respective layer causes mechanical residual stresses in the respective layer due to atomic radii deviating from the layer material. The mechanical stresses advantageously cause magnetic anisotropies. These anisotropies may be due to the location of the doping z. B. be influenced in lines or strip shape. The position of the doping can be influenced by introducing the nanoparticles only partially into the layer. This can be achieved by not depositing the nanoparticles together with the metal to be deposited (dispersion with the electrolyte), but instead applying them to the substrate in a separate coating step become. This coating step must take place before the electrochemical coating and can be done, for example, by cold gas spraying of the particles used.

The generated mechanical stresses have a positive effect on the magnetization losses in the transformer sheet.
This can be described as a model as follows. The mechanical stresses in the magnetically active layer lead to the retention of the so-called Bloch walls (these are the partitions of the white areas). Due to the immobility of the Bloch walls, the magnetic moments of entire white areas are reversed when an external magnetic field is applied. As a result, with the same energy of the primary coil of a transformer, the magnetic field of the material of the transformer core changes more. The greater change in the magnetic field induces greater energy in the secondary coil of the transformer. This advantageously reduces the loss of magnetization and increases the relative permeability number.

According to another particular embodiment of the invention, it is provided that in the transformer sheet or the transformer core as the starting layer for electrochemical coating between the separation layers and the soft magnetic layers, an electrically conductive material is provided whose thermal expansion coefficient is at least 10% and at most 30% of different from that of the soft magnetic layer. The conductive material is necessary in order to again be able to deposit a layer of the soft magnetic material on the electrically insulating separating layer. Since the separation layer itself can not serve as an electrode for the deposition of layer material, the application of the starting layer, for example by means of thermal Spraying or PVD process upstream of the electrochemical coating step.

By providing starting layers of a material whose thermal expansion coefficient differs from that of the soft magnetic layers, the already-described mechanism of generating residual stresses can be achieved as the material of the transformer core heats up during operation. This is due to the fact that the heating during operation of the transformer core is greater than during its production, for example by means of electrochemical deposition and cold gas spraying. Here is another benefit of using cold gas spraying. This means that the layers of the transformer core or transformer sheet can be largely without residual stresses and then arise during operation of the transformer by heating it. According to the mechanism already described above (use of particles with different atomic radii), the magnetization losses can advantageously be reduced and the relative permeability number increases.

In addition, one obtains an advantageous embodiment of the invention, when the soft magnetic layers and / or lying between the separation layers and the soft magnetic layers start layers for electrochemical deposition are doped with hard magnetic particles, wherein the magnetic field with respect to its field line at least substantially on the planned field line course in the transformer core or transformer sheet is aligned. This can be advantageously stabilized in the operation of the transformer, the required field line profile of the magnetic field to be generated. In addition, the magnetic properties of the resulting composite material between those of an amorphous layer and those of a nanocrystalline Set metal. This applies to the electrochemically deposited matrix in which the magnetic particles are incorporated. Thus, a subsequent heat treatment of the amorphous material with which normally amorphous microstructural orders can be converted into nanocrystalline can be saved. The adjustment of the microstructure of the matrix between amorphous and nanocrystalline is advantageously much more accurately possible by means of the incorporated particles. It can then be further displaced by a heat treatment in the direction of nanocrystalline structural orders. In itself, however, it is the aim of the incorporation of the nanoparticles according to the invention that an application-specific optimized combination with the matrix material results in a composite material with small hysteresis losses and high saturation magnetization. This results in the same size of the transformer core to the possibility of transmitting a larger energy or when transmitting the same amount of energy transformer cores, which have a smaller size. Advantageously, a more effective use of material or a lesser amount of cooling is required.
The object stated above is also achieved by a method for producing a transformer sheet or a transformer core consisting of a package of transformer laminations, in which a soft magnetic layer of an electrically conductive core material with an amorphous and / or transformer sheet is produced on a base body with an amorphous and / or or nanocrystalline microstructure is deposited electrochemically. An electrically insulating separating layer is then produced on this soft magnetic layer. Then, a starting layer for the electrochemical coating, a further soft magnetic layer after the already mentioned method step and a further separating layer after the already mentioned method step are produced repeatedly. This is repeated until the transformer sheet has the intended thickness has reached. This method is advantageous for the production of transformer plates or transformer cores in the manner already described above, which have the advantages already described. The electrochemical manufacturing method advantageously allows the production of extremely thin layers, so that the soft magnetic layers and the separating layers ensure effective prevention of eddy current losses. In addition, the transformer sheets produced according to the invention are easier to process, since the thicknesses of the sheets produced can be selected independently of the small thickness of the individual soft magnetic layers. The respective starting layers for the electrochemical coating are required because the separation layers due to their effect in the transformer plate (prevention of eddy current losses) must be electrically insulating. However, these are therefore not suitable for a further electrochemical deposition step. This can only take place if a starting layer for the electrochemical coating is again applied to the electrically insulating separating layers.
According to an advantageous embodiment of the method according to the invention it is provided that the coating with the soft magnetic layer by a reverse pulse plating takes place. This per se known electrochemical deposition method involves the insertion of pulsed Abscheideströmen for the coated workpieces. Preferably, the current pulses alternately change from cathodic to anodic currents, wherein the cathodic deposition must predominate on the workpiece as compared to the anodic dissolution to come to a deposition. The reverse pulse plating is particularly advantageous for the deposition of uniform layer thicknesses.

Advantageously, at least one soft magnetic element, in particular one or more of the elements Fe, Si, Ni or Co, and at least one glass-forming element, in particular P and / or B, are jointly deposited as a soft magnetic layer. The soft magnetic elements serve advantageously to produce a soft magnetic layer, wherein the glass formers are added to ensure the formation of an amorphous microstructure during the electrochemical deposition.

An embodiment of the method according to the invention provides that the layers produced in each case correspond exactly to the longitudinal section of the transformer core to be produced with a cutting plane aligned parallel to the course of the layer. In other words, the orientation of the layers is exactly in the direction that is usually used to laminate transformer sheets. The layer planes are thus such that the two center axes of the transformer windings lie in one of these layer planes. This is advantageous because the expansion of the transformer core is the lowest across these layer planes and therefore the transformer core or, correspondingly, the transformer plates can be made with a minimum number of individual layers.

It is advantageous if the deposition of the starting layer takes place by atomization of powder, by thermal spraying (in particular cold gas spraying) or by PVD coating of an electrically conductive material. In other words, the electrically conductive material is applied to the previously applied electrically insulating release layer by atomizing, thermal spraying or PVD coating. This coating step can be carried out until the starting layer has the required thickness for a subsequent electrochemical coating. This is in particular achievable by the thermal spraying, since this method allows comparatively high deposition rates. Preferably, the cold gas spraying can be used, because this goes largely without a thermal load of the deposited particles of the starting layer and the substrate of Statte. A thermal load of the substrate should be avoided if the amorphous microstructure of the soft magnetic layers is to be completely retained. However, thermal spraying such as plasma spraying can also be used to achieve a targeted transformation of the deposited amorphous structure into a nanocrystalline structure by the thermal energy introduced in this way.

Advantageously, however, the deposition of the starting layer can also take place in two steps. After the above-described atomization, thermal spraying or PVD coating with the material of the starting layer and with an amount that is not sufficient for a galvanic deposition, can be carried out as an intermediate step electrochemical deposition of the electrically conductive material by an electroless method until the starting layer has reached the required thickness. In fact, even low layer thicknesses or not yet closed layers on the electrically insulating separating layer are sufficient for currentless deposition.

It is particularly advantageous if the electrically conductive material with which the starting layer is produced contains only chemical elements of the soft magnetic layer. This has the advantage that the starting layer after completion of the overlying soft magnetic layer so to speak merges with this and no longer appears as a separate layer in appearance. This will influence the product to be produced Product of transformer core or transformer sheet.

A particular embodiment of the method according to the invention is obtained when a base body made of a soft magnetic, electrically conductive material, in particular with an amorphous and / or nanocrystalline microstructure is used. The base body, which is always required for an electrochemical coating to provide a substrate for coating, can according to this advantageous embodiment support the function of the transformer sheet or of the transformer core in the same way as the subsequently produced soft magnetic layers. In particular, if the base body consists of an amorphous and / or nanocrystalline structure, a performance comparable to the soft magnetic layers can be achieved. The same applies to soft magnetic nanoparticles which can be incorporated into the soft magnetic layers and / or starter layers in order to influence the microstructure there in the manner already described. The microstructure can be influenced in such a way that a specific ratio of the proportions of amorphous and / or nanocrystalline microstructures can be set. This advantageously eliminates post-treatment of the layers for adjusting the microstructure (heat treatment), which, however, can optionally be carried out to correct the properties of the layers produced. The incorporation of soft magnetic nanoparticles can advantageously also be promoted in that they are deposited in a magnetic field or the substrate is magnetized during the deposition. In this way, the incorporation rates of nanoparticles can be influenced, wherein in addition to the concentration of the nanoparticles to be incorporated in the electrolyte, a parameter for adjusting the particle concentration available stands. This can be used in particular to shift a rate of incorporation to higher values, since the concentration of nanoparticles that can be dispersed in the electrolyte is limited (otherwise the nanoparticles precipitate out of the suspension again).

Alternatively, it can also be advantageously provided that hard-magnetic particles are incorporated into the soft-magnetic layers and / or the starting layers, during the deposition process the forming layer being exposed to a magnetic field whose field line profile at least substantially corresponds to the planned field line profile in the transformer core to be produced. The advantages of a soft magnetic layer or so produced transformer sheets or transformer cores thus produced has already been explained. By means of the deposition process, the hard magnetic particles, the magnetization of which does not change during operation of the transformer, are fixed in a certain orientation in the surrounding matrix of the structure, for which reason the magnetic field generated by them during operation of the transformer superimposes the magnetic field due to the processes taking place in the transformer , As a result, the magnetic field in the transformer is stabilized and deviations from the desired field line course are attenuated. Furthermore, it is advantageously possible to carry out a targeted correction of the magnetic field generated during operation in the transformer. In order to accomplish this, deviations must be intentionally provided for the magnetic field which is used during the deposition process of the forming layers, which produces an orientation of the hard magnetic particles with intended deviations from the planned field line course in the transformer core to be produced. As a result, a magnetic field with deviating in the later operation of the transformer by the built-hard magnetic particles Field line history compared to the planned field line history produced in the transformer core. The deviating magnetic field then corrects the magnetic field actually produced in the transformer core in the desired manner, whereby, for example, unwanted deviations of the actually generated field line profile of a transformer from the desired field line course can be corrected.

Furthermore, it can be advantageously provided in the method according to the invention that nanoparticles are incorporated in the starting layers and / or in the separating layers, which, like the relevant layer in which they are incorporated, are electrically conductive or electrically insulating. The chemical elements of the nanoparticles are selected such that their incorporation into the matrix of the respective layer by means of atomic radii deviating from the layer material lead to mechanical residual stresses in the relevant layer. With this embodiment of the method, it is therefore possible to generate residual stresses in the product to be produced, whose positive effects (reduction of the magnetization loss and increase in the permeability number) have already been described above. The positive effect is due to the immobilization of the Bloch walls. In the same way, an electrically conductive material whose thermal expansion coefficient differs by at least 10 and at most 30% from that of the soft magnetic layers can advantageously be deposited for the starting layers. This also makes it possible to generate residual stresses during operation due to the heating of the transformer core, which positively influence the magnetic behavior of the transformer in the manner already described.

In the following, possible parameters for the production of the transformer cores or transformer plates by means of electrochemical coating will be explained by way of example. The production of a transformer sheet is then carried out by a sequence of the described basic steps simultaneously on both sides in order to halve the required coating time. The basic body is first produced by phosphating with an electrical insulation layer. Depending on the material of the base body, for example, iron phosphate or zinc phosphate is formed. In a next step, a starting layer is applied to the electrically insulating separating layer of phosphate for a subsequent electrochemical deposition. This can be done by a first intermediate step, in which conductive iron or nickel is applied in the form of powders by atomization or cold gas spraying. Alternatively, the metal can also be applied by sputtering or vapor deposition, which is worthwhile, above all, for small workpieces. In a second step, iron, iron phosphorous, nickel or an iron-nickel alloy is electrodeposited by electroless deposition until the layer so formed has received sufficient thickness for a subsequent electrodeposition step (i.e., applying a deposition current). Then, the galvanic deposition of an amorphous iron-phosphorus alloy or a nickel-iron alloy, which forms the soft magnetic layer. This can be done in detail as follows.

The base body used is a degreased, cleaned and activated metal foil of, for example, 20 μm thick, which consists of iron, nickel or a nickel-iron alloy. This is phosphated on both sides by dipping, spraying or electrochemical. The phosphating is carried out with an iron phosphate or zinc phosphate-containing solution and subsequent Drying at below 100 ° C. The chemicals required for this purpose can be obtained, for example, from SurTec.

The phosphating may also be cathodic using an electrolyte which may contain one or more of the following types of ions: Zn ²⁺ , Ca ⁺ , PO ₄ ³⁺ , NO ₃ ^- or ClO ₃ ^- or F ^- . This electrochemical deposition can be carried out at a temperature of 25 ° C a pH between 1 and 4 and a current density between 5 and 250 mA / cm ² . By varying the current density and the other conventional deposition parameters, it is possible to produce different layer thicknesses of up to 100 μm (preferably 1 to 20 μm). By means of a pulse plating, the layer can also be produced with pores, which in a next step serve to take up nickel, iron or nickel iron particles.

The step of coating with said particles is preferably accomplished by atomization or by cold gas spraying. This is done by an electroless deposition of an iron phosphorus alloy or nickel with a layer thickness of preferably 0.3 microns. The electrolyte used contains iron sulfate, sodium hypophosphite, potassium sodium tartrate, boric acid and small amounts of sugar acid. A pH of 8 to 11.5 is set with 15% sodium hydroxide solution, the electroless deposition process being carried out at 50 to 85 ° C. At 80 ° C and a pH of 10.5 to obtain an iron phosphorus alloy with 94.5 wt .-% iron and 5.5 wt .-% phosphorus.

For nickel deposition, an electrolyte containing nickel sulfate, sodium glycolate, and sodium hypophosphite may be used. With sodium hydroxide solution, the pH to 4 set to 5. The electroless deposition is carried out at a bath temperature between 90 and 95 ° C.

As soon as a closed starting layer is present, the electrochemical deposition of the amorphous iron-phosphorus or nickel-iron alloy can now take place. This electrochemical deposition of the soft magnetic layer is carried out with deposition baths consisting of aqueous solutions of iron (II) salts. For example, iron (II) chloride, iron (II) sulfate, iron (II) fluoroborate or iron (II) sulfamate can be used. As the phosphorus donor, a hypophosphite or orthophosphite is used (for example, sodium hypophosphite or sodium orthophosphite). This produces the desired iron-phosphorus alloys in the layer. In the electrodeposition, soluble anodes of iron, preferably of pure iron, or insoluble anodes, for example of platinized titanium, may be used. The deposition takes place at temperatures between 40 and 70 ° C. The selected current density is 10 to 100 A / dm ² . The deposition process can be carried out by a DC process or particularly advantageously by reverse pulse plating.

When nickel-iron deposition is to be carried out, an electrolyte consisting of, for example, nickel chloride, iron chloride, sodium chloride, sodium saccharin, sodium lauryl sulfate and boric acid may be used. The deposition takes place at 30 ° C. and a pH of 3 with a current density of 0.5 to 8 A / dm ² . The anodes used are nickel or iron anodes. After reaching the required layer thicknesses (eg 0.23 mm), the phosphating process step already described above is repeated.

If transformer sheets are produced by the method described above, the required shape can be achieved in various ways. Either the transformer sheet is produced over a large area as a semifinished product, wherein the known forms for the transformer sheets in the form of an E and I are produced by separating the transformer sheet (for example punching). But it is also possible to bring the base body in the required form of the transformer sheet and then to coat, the transformer sheet is then formed immediately in its required shape. In order to guarantee the dimensional accuracy, in particular a coating after the reverse pulse plating is particularly advantageous. In this way, transformer sheets in all common configurations (M, EI, UI and LL) as well as sheet metal strips for the production of cut cores or even annular transformer sheets for the direct, gapless production of toroidal cores can be produced. Selected intermediates of the method exemplified above are described in U.S.P. FIGS. 4 to 7 described in more detail.

Figur 1

eine Anordnung für das elektrochemische Beschichten eines Transformatorbleches als Ausführungsbeispiel des erfindungsgemäßen Verfahrens,

Figur 2

den Stromverlauf eines Reverse Pulse Platings als Ausführungsbeispiels des erfindungsgemäßen Verfahrens,

Figur 3

den Prozess der Schichtentstehung bei einem Verfahren gemäß Figur 2 in einem Ausschnitt des Bauteils,

Figur 4

bis 7 verschiedene Zustände bei der Entstehung von Ausführungsbeispielen des erfindungsgemäßen Transformatorbleches als Schnitt bei der Durchführung eines Ausführungsbeispiels des erfindungsgemäßen Verfahrens und

Figur 8 und 9

die Ausschnitte VIII und IX aus den Figuren 6 und 7.

Further details of the invention will become apparent from the drawing, wherein in the figures the same or corresponding drawing elements are each provided with the same reference numerals and only to that extent be explained several times, as revealed by differences between the individual figures. Show it

FIG. 1

an arrangement for the electrochemical coating of a transformer sheet as an embodiment of the method according to the invention,

FIG. 2

the current profile of a reverse pulse plate as an embodiment of the method according to the invention,

FIG. 3

the process of layer formation in a method according to FIG. 2 in a section of the component,

FIG. 4

to 7 different states in the formation of embodiments of the transformer sheet according to the invention as a section in carrying out an embodiment of the method according to the invention and

FIGS. 8 and 9

the excerpts VIII and IX from the FIGS. 6 and 7 ,

FIG. 1 shows a galvanic bath 11, which is suitable for coating a base body 12 of a transformer sheet. This body is annular and therefore already has the shape of the transformer sheet to be installed. The main body 12 should be coated on both sides, which is why counter electrodes 13 are arranged on both sides and correspond in their extent to the base body 12 in order to produce the most uniform possible electric field in the electrolyte 14 used. The base body 12, which forms the working electrode, and the counter-electrodes 13 are connected to one another via a controller 15, it being possible to control the deposition current via the controller 15.

One possible control of the separation stream is in FIG. 2 shown. At the switched as a working electrode body 12 according to FIG. 1 is the deposition current density i on. This is according to FIG. 2 considered over time t. Alternately In the case of reverse pulse plating, cathodic current pulses having a deposition current density i _c and anodic current pulses having a deposition current density i _{a are} generated. Taking into account the respective associated pulse length t _c and t _a is to be considered in the leadership of the reverse pulse Platings that a total of a layer structure must be made. This presupposes that the integrals of the current density i over the time t Q _{c of} the cathodic current pulse are greater than Q _{a of} the anodic current pulse.

Due to the current flow, a layer growth can be generated, as in FIG. 3 is shown. At the edges, the irregularities 16 during cathodic layer growth, represented by the contour 17, can be largely corrected, since in the subsequent anodic current pulse the irregularity 16 is degraded disproportionately and the contour 18 is present after the anodic current pulse. In this case, the anodic dissolution of the material is less than the cathodic growth, which is why deposited material remains on the base body 12. The process is according to FIG. 3 shown greatly exaggerated to visualize the course of the contours 17, 18.

The in the FIGS. 4 to 7 represented intermediates of the method according to the invention can be produced with the above-mentioned examples of the method according to the invention.

In FIG. 4 the main body 12 is shown as a foil. This is already provided on both sides with an electrically insulating separation layer 19 by phosphating. On the release layer 19 further particles 20 are applied to a start layer 21, which FIG. 5 can be removed. The particles 20 can be, for example, by atomizing are applied to the release layer 19 and are in FIG. 5 no longer recognizable, since the starting layer 21 consists of the same material as the particles 20. In a subsequent process step (not shown), electrochemical coating on the starting layer 21 with the material of soft magnetic layers 22 (see FIG FIG. 6 ) respectively. These ensure the function of the transformer core.

In FIG. 7 It is shown how, in each case, a separation layer 19 was again formed on the base body after the application of the soft magnetic layers 22 on both sides, and in each case particles 20 for a starting layer were deposited on the separation layers 19 thus formed. The following can be added to FIG. 5 Repeated steps are repeated as often as desired until the desired thickness of the transformer plate or the desired shape of the transformer core is reached. The starting layers 19 used can in this embodiment be formed, for example, from copper. Thus, there is always a layer of copper between the separating layers 19 and the soft magnetic layers 22 in the direction of the layer formation, which corresponds to the in FIG. 7 causes layer structure.

In FIG. 6 a layer structure is shown, in which the particles 20 are made of the same material as the soft magnetic layer 22. After application of the particles 20 then forms a layer structure, the in FIG. 5 is similar. However, the separation layers 21 in the layer composite according to FIG. 6 no longer recognizable, since these together with the soft magnetic layers 22 result in a single microstructure.

The FIGS. 8 and 9 It can be seen schematically how the incorporation of particles in different layers of the layer composite according to the invention for transformer sheets can be done. According to FIG. 8 For example, in the soft magnetic layer 22 made of nickel iron, nanoparticles 23 are also made of nickel iron. The soft magnetic layer 22, which grows amorphous during electrochemical coating, can thus be provided in a targeted manner with a nanocrystalline structure. Shown in dashed lines are grain boundaries 24, which are formed by the incorporation of the nanoparticles 23 and thus allow structure grains with nanocrystalline dimensions to form in the amorphous matrix of the layer 22. Furthermore, the nanoparticles 23 themselves may also be formed amorphous or crystalline. In the event that the nanoparticles 23 themselves are crystalline (as in FIG FIG. 8 represented by the nanoparticles further grains in the amorphous matrix of the layer 22, so that in FIG. 8 represented contours of the particles 23 also represent grain boundaries. If the particles 23 themselves were amorphous, they would fuse with the amorphous matrix of the soft magnetic layer 22 and would be virtually invisible.

In order to induce anisotropy and consequently to induce residual stresses, nanocrystalline particles 25 of a FeCuNbSiB alloy or of amorphous iron alloys (eg FeSiB alloy) may be introduced into the starting layer 21 of metal, which may consist for example of cobalt. These particles are dispersed in the electroless plating deposition electrode and then co-deposited with the starting layer 21. The concentration of the particles 25 can be adjusted by the temperature, the speed of movement of the electrolyte (agitation) and the composition of the electrolyte.

Furthermore, nanoparticles 26 of Al ₂ O ₃ or CrO ₃ can be introduced into the separating layer 19 (cf. FIG. 9 ). These nanoparticles 26 also lead to residual stresses and therefore improve the manufactured transformer sheet in the manner already mentioned above. The nanoparticles 26 can either be admixed to the electrolyte during an electrochemical phosphating or a precursor during the phosphating by dipping or spraying and are then automatically incorporated into the applied layer.

Anisotropy of the microstructure due to different coefficients of expansion can also be produced by using a suitable material such as gold, silver, copper or aluminum as starting layer 21. These metals generate the residual stresses when heating the transformer sheet by their deviating from the adjacent layers expansion coefficient.

In FIG. 9 Also shown is the introduction of magnetic particles 27, which may also be designed as nanoparticles. Schematically illustrated is a magnetic field 28, which has the magnetic particle 27 and which is aligned in the direction of the desired field line course in the soft magnetic layer 22. For the magnetic particles 27, all known hard magnetic alloys can be used.

Claims (20)

1. Transformer plate having a soft magnetic layer (22) of an electrically conductive core material with an amorphous and/or nanocrystalline microstructure which is coated with a separating layer (19) of an electrically insulating material,
   characterized in that
   multiple of said soft magnetic layers (22) form, at least with the separating layers (19) between them, a monolithic assembly.
2. Transformer plate according to Claim 1,
   characterized in that
   this has a thickness of between 0.2 mm and 0.6 mm.
3. Transformer core having soft magnetic layers (22) of an electrically conductive core material with an amorphous and/or nanocrystalline microstructure which are separated from one another by separating layers (19) of an electrically insulating material, wherein multiple of said soft magnetic layers (22) form, at least with the separating layers (19) between them, a monolithic assembly,
   characterized in that
   this assembly consists of a plate stack, wherein the transformer plates each consist entirely of a monolithic assembly of soft magnetic layers (22) and separating layers (19) .
4. Transformer core or transformer plate according to one of the preceding claims,
   characterized in that
   the soft magnetic layers (22) have a thickness of 2 µm to 100 µm.
5. Transformer core or transformer plate according to one of the preceding claims,
   characterized in that
   the separating layers (19) have a thickness of 0.1 µm to 5 µm.
6. Transformer core or transformer plate according to one of Claims 1 to 5,
   characterized in that
   the separating layers (19) and/or the start layers (21) between the separating layers (19) and the soft magnetic layers (22) are doped with nano-particles (25) for an electrochemical deposition, which particles, like the respective layer in which they are integrated, are electrically conductive or electrically insulating, and the chemical elements thereof are chosen such that their integration into the matrix of the respective layer produces residual stresses in the respective layer owing to atomic radii that differ from the layer material.
7. Transformer core or transformer plate according to one of Claims 1 to 6,
   characterized in that
   an electrically conductive material is provided as start layers (21) for electrochemical coating between the separating layers (19) and the soft magnetic layers (22), the thermal expansion coefficient of this material differing from that of the soft magnetic layers by at least 10% and at most 30%.
8. Transformer core or transformer plate according to one of Claims 1 to 7,
   characterized in that
   the soft magnetic layers (22) and/or the start layers (21) between the separating layers (19) and the soft magnetic layers (22) are doped with hard magnetic particles (27) for an electrochemical deposition, wherein the magnetic field thereof, with respect to its field line profile (28), is oriented at least substantially on the planned field line profile in the transformer core or transformer plate.
9. Method for producing a transformer plate or a transformer core consisting of a stack of transformer plates, in which, to produce the transformer plate(s),

   • a soft magnetic layer (22) of an electrically conductive core material is electrochemically deposited on a substrate (12) and obtains an amorphous and/or nanocrystalline microstructure,

   • an electrically insulating separating layer (19) is generated on the soft magnetic layer (22) and

   • a start layer (21) for the electrochemical coating, another soft magnetic layer (22) as per the above-mentioned method step and another separating layer (19) as per the above-mentioned method step are generated repeatedly until the transformer plate has reached the intended thickness.
10. Method according to Claim 9,
    characterized in that
    coating with the soft magnetic layer (22) is done by reverse pulse plating.
11. Method according to either of Claims 9 and 10,
    characterized in that
    as the soft magnetic layer (22), at least one soft magnetic element, in particular one or more of the elements Fe, Ni or Co, and at least one glass-forming element, in particular P and/or B, are deposited together.
12. Method according to one of Claims 9 to 11,
    characterized in that
    layers generated in each case correspond exactly to the longitudinal section of the transformer core that is to be produced with a plane of section oriented parallel to the layer profile.
13. Method according to one of Claims 9 to 12,
    characterized in that
    the start layer (21) is deposited by powder atomization, by thermal spraying or by PVD coating of an electrically conductive material.
14. Method according to Claim 13,
    characterized in that
    after atomization, thermal spraying or PVD coating, a current-free, electrochemical deposition of the electrically conductive material takes place until the start layer (21) has reached the requisite thickness.
15. Method according to one of Claims 13 and 14,
    characterized in that
    the electrically conductive material contains only chemical elements of the soft magnetic layer (22).
16. Method according to one of Claims 9 to 15,
    characterized in that
    a substrate of a soft magnetic, electrically conductive material, in particular having an amorphous and/or nanocrystalline microstructure, is used.
17. Method according to one of Claims 9 to 16,
    characterized in that
    soft magnetic nano-particles (23) are integrated into the soft magnetic layers (22) and/or the start layers (21).
18. Method according to one of Claims 9 to 17,
    characterized in that
    hard magnetic particles (27) are integrated into the soft magnetic layers (22) and/or the start layers, wherein during the deposition process the layer being formed is subject to a magnetic field, whose field line profile corresponds at least substantially to the planned field line profile in the transformer core that is to be produced.
19. Method according to one of Claims 9 to 18,
    characterized in that
    nano-particles (26) are integrated into the start layers (21) and/or the separating layers (19), which particles, like the respective layer in which they are integrated, are electrically conductive or electrically insulating, and the chemical elements thereof are chosen such that their integration into the matrix of the respective layer produces residual stresses in the respective layer owing to atomic radii that differ from the layer material.
20. Method according to one of Claims 9 to 19,
    characterized in that
    an electrically conductive material is deposited as start layers (21), the thermal expansion coefficient of this material differing from that of the soft magnetic layers by at least 10% and at most 30%.

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