Soft magnetic composite material plate, and iron core and rotary electric machine employing soft magnetic composite material plate

Abstract

Provided are a soft magnetic composite material plate capable of reducing iron loss more than before without significantly impairing magnetization characteristics inherent to a soft magnetic material, and an iron core and a rotary electric machine employing the soft magnetic composite material plate. A soft magnetic composite material plate according to the present invention is characterized in that it is obtained by combining a soft magnetic material and an electrically insulating film. The soft magnetic material has a filament shape. The electrically insulating film contains a lead-free glass composition and has a linear expansion coefficient smaller than that of the soft magnetic material by at least 3 ppm / K. The electrically insulating film is formed on the surface of the filament-shaped soft magnetic material to form a soft magnetic composite wire. The soft magnetic material and the electrically insulating film are integrated so that the longitudinal direction of the soft magnetic composite wire is arranged in the in-plane direction of the plate shape of the soft magnetic composite material plate.

Description

Soft magnetic composite plate, iron core and rotating electric machine using said soft magnetic composite plate

[0001] The present invention relates to soft magnetic material technology, and more particularly to a soft magnetic composite plate exhibiting low iron loss, an iron core using the soft magnetic composite plate, and a rotating electric machine.

[0002] Laminated cores made by laminating multiple soft magnetic material sheets (e.g., 0.01 to 3 mm thick), such as electromagnetic pure iron sheets or electromagnetic steel sheets, are widely used in electrical machinery devices (e.g., rotating electrical machines and transformers).From the perspective of protecting the global environment, the application fields of electrical machinery devices using soft magnetic materials have been expanding in recent years, and as a result, there has been an increasing demand for higher output and efficiency in these electrical machinery devices.

[0003] When considering a rotating electric machine as an electromechanical device, its output is proportional to the product of the torque and the rotational speed during operation, so increasing either the torque or the rotational speed can increase output. Torque is proportional to the product of the magnetic flux density and the current value. To increase torque, it is desirable to use soft magnetic materials that achieve high saturation magnetic flux density Bs and / or high saturation magnetization Ms. Various methods of controlling the composition and microstructure of soft magnetic materials are being used to increase Bs / Ms.

[0004] When increasing the rotation speed during operation, the conversion efficiency between electrical energy and magnetic energy is important, and reducing the loss (iron loss Pi) in the soft magnetic material plate becomes a challenge. Reducing Pi also leads to reduced heat generation during operation. Pi is the sum of hysteresis loss and eddy current loss, and a small coercive force Hc is desirable to reduce hysteresis loss, while increasing electrical resistance and thinning the plate are effective in reducing eddy current loss.

[0005] Currently, Fe-Si alloy electrical steel sheets are widely used as a material that has a good balance between a relatively high Bs / Ms and a relatively low Pi. Fe-Co alloy sheets are known to have a higher Bs than Fe-Si alloy electrical steel sheets. In recent years, Fe (iron)-based amorphous alloy sheets and Fe-based nanocrystalline alloy sheets have also attracted attention as materials that have a lower Pi than Fe-Si alloy electrical steel sheets and Fe-Co alloy sheets.

[0006] On the other hand, since electromechanical devices using soft magnetic materials have a wide variety of applications and sizes, there has been active development of technology for the stable production of soft magnetic materials in order to meet the various required characteristics in the design of such electromechanical devices.

[0007] For example, in Patent Document 1 (JP 2022-113111), the alloy composition is represented by the formula (Fe 1-x A x ) a Si b B c Cu d M e where A is at least one of Ni and Co, and M is one or more selected from the group consisting of Nb, Mo, V, Zr, Hf, and W, and the atomic percentages are 82.4≦a≦86, 0.2≦b≦2.4, 12.5≦c≦15.0, 0.05≦d≦0.8, 0.4≦e≦1.0, and 0≦x≦0.1. The soft magnetic alloy ribbon has a structure in which crystal grains having a grain size of 60 nm or less exist in an amorphous phase, and has a saturation magnetic flux density of 1.74 T or more and an iron loss at 1 kHz and 1 T of 25 W / kg or less.

[0008] According to Patent Document 1, it is possible to obtain a soft magnetic alloy ribbon having a high saturation magnetic flux density and low iron loss, and a method for manufacturing the same.

[0009] Japanese Patent Application Laid-Open No. 2022-113111

[0010] As mentioned above, there is a growing demand for increasing the output power (e.g., power density W / kg) of electromechanical devices. Recently, increasing the rotation speed and / or frequency during operation has been promoted as a means of increasing the output power of electromechanical devices. However, increasing the rotation speed and / or frequency poses a major problem of energy loss and efficiency reduction due to the Pi of soft magnetic materials. In other words, in order to increase the power density and efficiency of electromechanical devices, it is desirable for soft magnetic materials to have both a high Bs / Ms and a low Pi.

[0011] The present invention has been made to achieve the above-mentioned object, and its primary object is to provide a soft magnetic composite sheet that can reduce Pi more than conventionally without significantly impairing the Bs / Ms characteristics inherent in soft magnetic materials, and an iron core and a rotating electric machine that use the soft magnetic composite sheet.

[0012] (I) One aspect of the present invention provides a soft magnetic composite plate in which a soft magnetic material and an electrically insulating coating are combined, wherein the soft magnetic material has a filament shape; the electrically insulating coating includes a lead-free glass composition and has a linear expansion coefficient that is 3 ppm / K or more smaller than the linear expansion coefficient of the soft magnetic material; a soft magnetic composite wire is formed in which the electrically insulating coating is formed on the surface of the filament-shaped soft magnetic material; and the soft magnetic composite wires are integrated so that their longitudinal directions are aligned in the in-plane direction of the plate shape of the soft magnetic composite plate.

[0013] In the present invention, the linear expansion coefficients of the soft magnetic material and the electrical insulating coating are defined as the average linear expansion coefficients from room temperature to the glass transition point Tg of the electrical insulating coating.

[0014] The present invention allows the soft magnetic composite plate (I) of the present invention to be modified in any combination as follows: (i) The thickness of the soft magnetic composite plate is 0.01 mm or more and 3 mm or less, the space factor of the soft magnetic material is 80 volume % or more, and the average thickness of the electrically insulating coating is less than 10% of the diameter of a circle having an equivalent area of ​​the cross section of the filament shape. (ii) The glass composition, when its nominal components are expressed in terms of oxides, contains 40% by mass or more and 70% by mass or less of V2O5 (vanadium oxide) and 10% by mass or more and 35% by mass or less of P2O5 (phosphorus oxide), the sum of the V2O5 and the P2O5 being 50% by mass or more and 98% by mass or less; the glass composition contains two or more elements selected from the group consisting of BaO (barium oxide), Sb2O3 (antimony oxide), WO3 (tungsten oxide), ZnO (zinc oxide), K2O (potassium oxide), Fe2O3 (iron oxide), TeO2 (tellurium oxide), Ag2O (silver oxide), and Li2O (lithium oxide) in a total amount of 2% by mass or more and 50% by mass or less, with the remainder being unavoidable impurities; and the softening point of the glass composition is 500°C or less. (iii) The electrical insulating coating contains 75% by volume or less of a filler material of oxide particles, and the filler material is one or more of the group consisting of SiO2 (silicon oxide), ZrO2 (zirconium oxide), Al2O3 (aluminum oxide), Nb2O5 (niobium oxide), ZrSiO4 (zirconium silicate), Zr2(WO4)(PO4)2 (zirconium tungstate phosphate), 2MgO.2Al2O3.5SiO2 (cordierite), 3Al2O3.2SiO2 (mullite), and LiAlSiO4 (eucryptite). (iv) The linear expansion coefficient of the electrical insulating coating is less than 10 ppm / °C. (v) The soft magnetic material experiences a tensile strain in the range of 10 μST to 1000 μST along its longitudinal direction.

[0015] (II) Another aspect of the present invention provides an iron core made of a laminate of soft magnetic composite material plates, wherein the soft magnetic iron alloy plates are the soft magnetic iron alloy plates according to the present invention, and the soft magnetic composite wires are arranged so that the longitudinal direction of the soft magnetic composite wires is parallel to the magnetization direction applied to the soft magnetic composite material plates.

[0016] (III) Yet another aspect of the present invention provides a rotating electric machine having an iron core, characterized in that the iron core is the iron core according to the present invention described above.

[0017] According to the present invention, it is possible to provide a soft magnetic composite plate that can reduce Pi more than conventionally without significantly impairing the Bs / Ms characteristics that the soft magnetic material originally has, and an iron core and a rotating electric machine that use the soft magnetic composite plate.

[0018] Problems, configurations, and effects other than those described above will become clear from the description of the embodiments below.

[0019] Fig. 1 is a partially enlarged schematic perspective view showing an example of the structure of a soft magnetic composite iron core according to the present invention. Fig. 2 is a schematic perspective view showing an example of an iron core according to the present invention. Fig. 3 is a schematic perspective view showing an example of a stator for a rotating electric machine. Fig. 4 is an enlarged schematic cross-sectional view of a slot region of a stator. Fig. 5 is an example of a chart obtained during the temperature rise process of differential thermal analysis for a glass composition used as an electrical insulating coating in the present invention. Fig. 6 is a flow chart showing an outline of a method for manufacturing an iron core using a soft magnetic composite plate according to the present invention. Fig. 7 is a schematic plan view showing an example of an arrangement of soft magnetic composite wires in a soft magnetic composite plate according to the present invention.

[0020] [Basic Concept of the Present Invention] As mentioned above, Pi is the sum of hysteresis loss and eddy current loss, and increasing the electrical resistance of soft magnetic material sheets and reducing their thickness are considered effective ways of reducing eddy current loss. The present inventors have conducted various studies on technologies for further reducing Pi in soft magnetic material sheets.

[0021] In this research, it was found that increasing the electrical resistance by partially replacing the constituent components of soft magnetic materials and simply thinning the soft magnetic material tend to lead to a decrease in the Bs / Ms characteristics. On the other hand, it was found that applying tensile strain in the in-plane direction of the soft magnetic material plate may be able to reduce hysteresis loss. Furthermore, it was found that it is preferable to align the tensile strain applied to the soft magnetic material plate with the magnetization direction of the soft magnetic material plate.

[0022] The inventors of the present invention have further intensively researched means for reducing Pi below conventional values ​​without significantly impairing the inherent Bs / Ms characteristics of soft magnetic materials. As a result, they have found a possible solution in a method in which soft magnetic material is filamentized to reduce the eddy current area, and an electrically insulating coating having a smaller linear expansion coefficient than the soft magnetic material is formed on the surface of the soft magnetic filaments to reduce hysteresis loss, thereby forming a soft magnetic composite wire that is subjected to tensile strain, and then bundling the soft magnetic composite wires to form a plate shape. The present invention was completed based on this finding.

[0023] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the specific embodiments described, and can be appropriately combined with or improved on known techniques without departing from the technical concept of the invention.

[0024] [Soft Magnetic Composite Plate and Iron Core of the Present Invention] Fig. 1 is a partially enlarged perspective schematic view showing an example of the structure of a soft magnetic composite plate of the present invention, and Fig. 2 is a perspective schematic view showing an example of an iron core of the present invention. As shown in Fig. 1, a soft magnetic composite plate 20 of the present invention is formed by bundling multiple soft magnetic composite wires 10, each of which has an electrically insulating coating 2 formed on the surface of a filament-shaped soft magnetic material (soft magnetic filament 1), and integrally molding the bundled wires into a plate shape. The soft magnetic composite plate 20 can be suitably used, for example, as a soft magnetic plate for a segmented iron core. Furthermore, as shown in Fig. 2, an iron core 30 of the present invention is formed by stacking multiple soft magnetic composite plates 20 together.

[0025] In Fig. 1, the cross section of the soft magnetic composite plate 20 shows four layers of soft magnetic filaments 1 stacked in a square arrangement in the thickness direction, but the present invention is not limited to this. For example, the soft magnetic filaments 1 may be stacked in one to three layers, five or more layers, or a hexagonal arrangement. There is no particular limitation on the thickness of the soft magnetic composite plate 20, but when used as a constituent material for a laminated iron core, a thickness of 0.01 mm or more and 3 mm or less is preferable.

[0026] [Stator and rotating electric machine using the soft magnetic composite plate of the present invention] Figure 3A is a schematic perspective view showing an example of a stator for a rotating electric machine, and Figure 3B is an enlarged schematic cross-sectional view of a slot region of the stator. Note that the cross-sectional view refers to a cross section perpendicular to the rotation axis direction (a cross section whose normal is parallel to the axial direction). In a rotating electric machine, a rotor (not shown) is disposed radially inside the stator shown in Figures 3A and 3B.

[0027] 3A and 3B, the stator 40 has stator coils 41 wound in multiple stator slots 31 formed on the inner periphery of the core 30. The stator slots 31 are spaces that are arranged at a predetermined circumferential pitch around the circumferential direction of the core 30 and penetrate the core 30 in the axial direction, with slits 32 opening in the axial direction at the innermost periphery. The areas separating adjacent stator slots 31 are called teeth 33 of the core 30, and the parts of the inner periphery tip areas of the teeth 33 that define the slits 32 are called tooth claw portions 34. The outer periphery parts connecting adjacent teeth 33 are called yokes 35 of the core 30.

[0028] The stator coil 41 is typically made up of multiple segment conductors 42. For example, in Figures 3A and 3B, the stator coil 41 is made up of three segment conductors 42 corresponding to the U, V, and W phases of a three-phase AC. Furthermore, in order to prevent partial discharge between the segment conductors 42 and the iron core 30 and between the phases (U, V, and W), the outer periphery of each segment conductor 42 is typically covered with an electrical insulating material 43 (e.g., insulating paper or enamel coating).

[0029] The rotating electric machine referred to here is a rotating electric machine that uses an iron core 30 made of the soft magnetic composite material plate 20 of the present invention. The iron core 30 can reduce Pi more than conventionally without significantly impairing the Bs / Ms characteristics inherent in soft magnetic materials, and therefore can suitably accommodate higher rotation speeds and higher frequencies while suppressing energy loss and efficiency decline in the rotating electric machine. As a result, the rotating electric machine can improve its power density more than conventionally.

[0030] The structure of the soft magnetic composite plate 20 will now be described in detail.

[0031] (Soft Magnetic Filament) There is no particular limitation on the soft magnetic material used in the present invention, but from the viewpoint of Bs / Ms, it is preferable to use a material that exhibits a higher Bs / Ms than Fe-Si alloy-based electrical steel sheet (e.g., electromagnetic pure iron material, Fe-Co alloy material, Fe-N alloy material, Fe-Co-N alloy material, etc.). Also, from the viewpoint of Pi, it is preferable to use a material that is suitable for reducing Pi (e.g., Fe-Co alloy material, Fe-Co-N alloy material, Fe-based amorphous alloy material, Fe-based nanocrystalline alloy material, etc.).

[0032] In the present invention, the Fe-based nanocrystalline alloy material basically means an alloy material in which an Fe-based nanocrystalline alloy phase is finely dispersed in a matrix of an Fe-based amorphous alloy phase, but it may also be an alloy material composed only of an Fe-based nanocrystalline alloy phase.

[0033] Regarding the filament shape, although Fig. 1 illustrates a case where the filament cross section is rectangular, the present invention is not limited thereto. For example, the filament cross section may be circular, elliptical, hexagonal, or flat. There are no particular limitations on the filament diameter, but assuming that the final thickness of the soft magnetic material plate is 0.01 to 3 mm, it is preferable to control the filament diameter so that the diameter of the equivalent area circle of the cross section is 0.008 mm to 2.5 mm.

[0034] Furthermore, when the soft magnetic composite plate 20 of the present invention is used as a constituent material of a laminated iron core, it is preferable that the space factor of the soft magnetic filaments 1 in the soft magnetic composite plate 20 be 80 volume % or more in order to ensure desirable magnetic properties (e.g., magnetic flux density of the iron core).

[0035] (Electrical insulating coating) The electrical insulating coating 2 preferably has a linear expansion coefficient smaller than that of the soft magnetic filament 1 (usually 10 ppm / K or greater). When the electrical insulating coating 2 has a linear expansion coefficient smaller than that of the soft magnetic filament 1, compressive stress is applied to the electrical insulating coating 2 when the electrical insulating coating 2 is cooled from its formation temperature to room temperature, and tensile stress can be applied to the soft magnetic filament 1.

[0036] More specifically, the electrical insulating coating 2 is preferably made of a material that contains a lead-free glass composition and has a linear expansion coefficient that is at least 3 ppm / K smaller than that of the soft magnetic filaments 1. The linear expansion coefficient of the electrical insulating coating 2 is more preferably at least 5 ppm / K smaller, and even more preferably at least 10 ppm / K smaller, than that of the soft magnetic material.

[0037] Research by the present inventors has revealed that applying a tensile strain within the elastic deformation range to the soft magnetic filament 1 in the longitudinal direction can significantly reduce Pi. On the other hand, applying a tensile strain within the plastic deformation range to the soft magnetic filament 1 increases Pi. The amount of strain applied to the soft magnetic filament 1 is preferably in the range of 10 μST to 1000 μST (where ST means the amount of strain), more preferably in the range of 15 μST to 800 μST, and even more preferably in the range of 20 μST to 700 μST.

[0038] In addition, from the viewpoint of ensuring the space factor of the soft magnetic filaments 1 in the soft magnetic composite material plate 20, the average thickness of the electrical insulating coating 2 is preferably less than 10% of the diameter of the equivalent area circle of the cross section of the soft magnetic filaments 1.

[0039] 4 is an example of a chart (DTA curve) obtained during the temperature rise process of differential thermal analysis (DTA) for the glass composition used as an electrical insulating coating in the present invention. As shown in FIG. 4, the onset temperature of the first endothermic peak is taken as the glass transition point Tg (viscosity = 10 13.3 The peak temperature of the first endothermic peak is the sag point Td (viscosity = 10 11.0 The peak temperature of the second endothermic peak is the softening point Ts (viscosity = 10 7.65 The peak temperature of the first exothermic peak is defined as the crystallization peak temperature Tcp. Each temperature is determined by the tangent method.

[0040] The lower the characteristic temperatures Tg, Td, and Ts of a glass composition, the more easily it softens and flows at low temperatures, and the lower the temperature at which the electrical insulating coating 2 can be formed. From the standpoints of workability and temperature controllability, it is desirable to form the electrical insulating coating 2 at a temperature that is approximately 20 to 50°C higher than Ts. On the other hand, if the glass composition crystallizes, the softening and flow properties are significantly impaired and the adhesion of the coating is also greatly reduced, so the coating must be formed at a temperature below Tcp.

[0041] For these reasons, the glass composition constituting the electrical insulating coating 2 preferably has a characteristic temperature such that the temperature difference between Ts and Tcp is at least about 20 to 50° C. More specifically, the glass composition used in the present invention preferably has a Ts of 500° C. or less, more preferably 450° C. or less, and even more preferably 420° C. or less.

[0042] Since it is undesirable for the electrical insulating coating 2 of the soft magnetic composite sheet 20 to soften and flow when the electromechanical device is used, it is preferable to set the Ts of the glass composition to be higher than the temperature at which the electromechanical device is used when using the soft magnetic composite sheet 20 of the present invention. For example, when the operating temperature of the electromechanical device is 150°C, it is preferable that the Ts of the glass composition be higher than 150°C.

[0043] From the viewpoint of environmental protection, the glass composition used in the present invention is preferably a lead-free glass composition, and when its nominal components are expressed as oxides, it contains 40% by mass or more and 70% by mass or less of V2O5 and 10% by mass or more and 35% by mass or less of P2O5, the total of V2O5 and P2O5 being 50% by mass or more and 98% by mass or less, and it contains two or more elements selected from the group consisting of BaO, Sb2O3, WO3, ZnO, KO, Fe2O3, TeO2, Ag2O, and Li2O in a total amount of 2% by mass or more and 50% by mass or less, with the remainder consisting of unavoidable impurities.

[0044] In the present invention, "lead-free" does not mean that lead components are intentionally contained, but it is acceptable that lead components are inevitably contained within a range below the value specified by the laws and regulations of each country.

[0045] In the glass composition used in the present invention, V2O5 is a component that contributes to lowering the glass softening flow temperature. P2O5 is a component that can form the glass skeleton and also contributes to suppressing crystallization of glass. BaO, Sb2O3, WO3, ZnO, K2O, and Fe2O3 are components that contribute to improving the moisture resistance and water resistance of glass and suppressing crystallization. TeO2 and Ag2O, like V2O5, are components that contribute to lowering the glass softening flow temperature. Li2O is a vitrifying component that contributes to improving adhesion and adhesion.

[0046] By controlling the above components and their contents, a lead-free glass composition having a desired characteristic temperature can be obtained. However, if the difference in the linear expansion coefficient between the soft magnetic filament 1 and the electrical insulating coating 2 is too small, sufficient tensile strain cannot be imparted to the soft magnetic filament 1.

[0047] Therefore, a filler may be mixed into the lead-free glass composition to control the linear expansion coefficient of the electrical insulating coating 2. Naturally, mixing a filler is not essential. Oxide particles are preferred as fillers in terms of compatibility with oxide glass. For example, one or more of the following may be suitably used: SiO2, ZrO2, Al2O3, Nb2O5, ZrSiO4, Zr2(WO4)(PO4)2, 2MgO·2Al2O3·5SiO2, 3Al2O3·2SiO2, and LiAlSiO4. The oxide particles are preferably spherical (e.g., with a minor axis / major axis ratio of 0.8 or greater).

[0048] The average particle size of the filler is preferably 0.1 μm to 10 μm, more preferably 0.5 μm to 5 μm. When a filler is mixed, the mixing ratio is preferably 75 vol% or less, more preferably 70 vol% or less, and even more preferably 5 vol% to 70 vol%.

[0049] Forming the electrical insulating coating 2 by mixing a filler into the glass composition has the advantage of being able to control the linear expansion coefficient of the electrical insulating coating 2 and also the viscosity during softening and flow. Another advantage is that controlling the average particle size and mixing ratio of the filler makes it easier to control the spacing between the soft magnetic filaments 1 (i.e., the thickness of the electrical insulating coating 2) when bundling the soft magnetic filaments 1 and molding them into an integrated structure.

[0050] [Method for manufacturing a soft magnetic composite plate and an iron core using the soft magnetic composite plate] Fig. 5 is a flow diagram showing an outline of a method for manufacturing an iron core using a soft magnetic composite plate according to the present invention. As shown in Fig. 5, first, a soft magnetic filament preparation step S1 for preparing a soft magnetic filament 1 and a paste preparation step S2 for preparing a paste that will be the basis for the electrical insulating coating 2 are performed. The order of steps S1 and S2 does not matter.

[0051] Next, the paste prepared in step S2 is applied to the surface of the soft magnetic filament 1 prepared in step S1 to form a soft magnetic composite wire precursor that serves as an intermediate material, and then an electrical insulating coating formation step S3 is performed in which the soft magnetic composite wire precursor is subjected to a predetermined heat treatment to form an electrical insulating coating 2. Through this step, a soft magnetic composite wire 10 is obtained.

[0052] Next, a soft magnetic composite plate forming step S4 is performed in which the soft magnetic composite wires 10 are bundled and molded while being subjected to a predetermined heat treatment to form the soft magnetic composite plate 20. Through this step, the soft magnetic composite plate 20 according to the present invention is obtained.

[0053] Next, an iron core formation step S5 is performed in which a plurality of soft magnetic composite plates 20 are stacked to form the iron core 30. At this time, although it is not an essential process, it is more preferable to subject the entire stacked soft magnetic composite plates 20 to a predetermined heat treatment to soften, flow, and harden the electrical insulating coating 2 again, thereby joining the soft magnetic composite plates 20 together. Through this step, the iron core 30 according to the present invention is obtained.

[0054] Each step will be described in more detail.

[0055] Step S1 is a step of preparing a soft magnetic filament 1. This step is not particularly limited as long as the desired soft magnetic filament 1 can be prepared, and a conventional metal processing method (for example, wire drawing from a rod material or cutting from a thin plate material) may be used, or the soft magnetic filament 1 may be procured from a commercially available soft magnetic material wire.

[0056] Step S2 is a step of preparing a paste that is the base of the electrical insulating coating 2. The paste is obtained by mixing a powder of the aforementioned lead-free glass composition or a frit obtained by mixing the powder with the aforementioned filler, with a resin binder and a solvent.

[0057] When a filler is mixed into the frit, as described above, the lead-free glass composition is preferably 25% by volume or more and 95% by volume or less, and the filler is preferably 5% by volume or more and 75% by volume or less. Nitrocellulose, for example, can be preferably used as a resin binder for the paste. Butyl carbitol acetate or α-terpineol, for example, can be preferably used as a solvent for the paste. The mixing ratios of the resin binder and the solvent can be adjusted appropriately, taking into account the ease of application of the glass paste.

[0058] In step S3, the paste prepared in step S2 is applied to the surface of the soft magnetic filament 1 prepared in step S1 to form a soft magnetic composite wire precursor that serves as an intermediate material, and then the soft magnetic composite wire precursor is subjected to a predetermined heat treatment to form an electrical insulating coating 2. In this way, a soft magnetic composite wire 10 is obtained.

[0059] The process for forming the soft magnetic composite wire precursor is not particularly limited to a specific application method, as long as the thickness of the paste coating film (e.g., on the order of μm) can be controlled. The prescribed heat treatment pattern includes, for example, a drying process in which the coating film is heated to and maintained at 120 to 200°C to dry out the moisture, binder components, and solvent components, followed by a firing process in which the coating film is heated to and maintained at a temperature 20 to 50°C higher than the Ts of the lead-free glass composition used. The maximum temperature of the firing process is lower than the Tcp of the lead-free glass composition used. When an Fe-based amorphous alloy material or an Fe-based nanocrystalline alloy material is used as the soft magnetic material, the maximum temperature is lower than the second crystallization temperature of the material.

[0060] The second crystallization temperature of Fe-based amorphous alloy materials and Fe-based nanocrystalline alloy materials is defined as the higher of the two large exothermic peaks observed during the heating process when DTA (differential thermal analysis) is performed on Fe-based amorphous alloy materials. The lower of the two large exothermic peaks is considered to be the exothermic reaction in which partial crystallization begins from the amorphous phase (the exothermic reaction in which the nanocrystalline alloy phase begins to nucleate and crystallize), and this peak temperature is defined as the first crystallization temperature. The higher peak is considered to be the exothermic reaction in which the original amorphous phase completely crystallizes and the nanocrystalline alloy phases begin to coalesce and coarsen.

[0061] After the electrical insulating coating 2 is formed by the firing process, when it is cooled, due to the difference in the linear expansion coefficients, compressive stress is applied to the electrical insulating coating 2 and tensile stress is applied to the soft magnetic filament 1. Ceramic materials are generally brittle to tensile stress but are very strong to compressive stress, so they can maintain / fix the soft magnetic filament 1 in a state where tensile strain is applied.

[0062] In order to adjust the tensile strain of the soft magnetic filament 1, the treatment may be carried out in a state where a tensile stress is applied to the soft magnetic filament 1.

[0063] In step S4, a plurality of the soft magnetic composite wires 10 prepared in step S3 are bundled and molded while being subjected to a predetermined heat treatment, thereby forming a soft magnetic composite plate 20. In this step, it is preferable to determine the magnetization direction that will occur in the iron core 30 when the soft magnetic composite plate 20 is used as the iron core 30 of an electric machine device, and then bundle and mold the plurality of soft magnetic composite wires 10 so that the magnetization direction and the longitudinal direction of the soft magnetic composite wire 10 coincide with each other.

[0064] Fig. 6 is a schematic plan view showing an example of the arrangement of soft magnetic composite wires in a soft magnetic composite plate according to the present invention. As shown in Fig. 6, in the portions that will become the teeth 33 of the iron core 30, it is preferable to arrange the soft magnetic composite wires 10 so that the radial direction of the soft magnetic composite plate 20 coincides with the longitudinal direction of the soft magnetic composite wires 10, and in the portions that will become the yoke 35 of the iron core 30, it is preferable to arrange the soft magnetic composite wires 10 so that the circumferential direction of the soft magnetic composite plate 20 coincides with the longitudinal direction of the soft magnetic composite wires 10.

[0065] The method of integral molding is not particularly limited, but since heating is performed while molding (molding while heating), for example, hot pressing or hot isostatic pressing (HIP) can be suitably used. The heat treatment pattern in step S4 is basically the same as step S3, except that differences in heat capacity of the heat-treated articles are taken into consideration and a drying process is not required.

[0066] In addition, if precise control of the shapes of the parts that will become the teeth 33 of the iron core 30 and the parts that will become the yoke 35 is not performed in the integral molding process of step S4, an additional soft magnetic composite plate shape processing step may be performed in which the integrally molded soft magnetic composite plate 20 is shaped using a conventional metal processing method (e.g., laser processing, water jet processing, etc.).

[0067] Step S5 is a step of laminating multiple soft magnetic composite plates 20 to form the iron core 30. At this time, a predetermined heat treatment may or may not be applied to the entire laminated soft magnetic composite plate 20. If the predetermined heat treatment is performed to soften, flow, and harden the electrical insulating coating 2 again and join the soft magnetic composite plates 20 together, the entire iron core 30 can be integrated, which has the advantage of contributing to the miniaturization of the iron core 30 and improving its vibration resistance. The heat treatment pattern in step S5 is the same as that in step S4.

[0068] As in step S4, an iron core shape processing step for precisely controlling the iron core 30 into a desired shape may be additionally performed as part of this step.

[0069] The present invention will be explained in more detail below with reference to various experiments, but the present invention is not limited to the configurations and structures described in these experiments.

[0070] [Experiment 1] (Preparation of Soft Magnetic Materials SM-1 to SM-4) Soft magnetic materials SM-1 to SM-4 were prepared as materials for the soft magnetic filament 1. A commercially available Fe-based amorphous alloy plate (Magprost Co., Ltd., 1K101, thickness 25 μm, length 70 mm, width 20 mm) was prepared as the soft magnetic material SM-1. A commercially available Fe-based nanocrystalline alloy plate (Magnet Institute Co., Ltd., NANOMET®, NMAQ, thickness 25 μm, length 70 mm, width 20 mm) was prepared as the soft magnetic material SM-2. NMAQ is a soft magnetic material plate that becomes an Fe-based nanocrystalline alloy plate by a specified nanocrystallization heat treatment.

[0071] A homemade Fe-Co alloy plate (80 atomic % Fe-20 atomic % Co, 100 μm thick, 70 mm long, and 20 mm wide) was prepared as the soft magnetic material SM-3. An Fe-Co-N alloy plate (79.5 atomic % Fe-19.5 atomic % Co-1 atomic % N, 100 μm thick, 70 mm long, and 20 mm wide) was prepared as the soft magnetic material SM-4 by nitriding SM-3.

[0072] (Preparation of Soft Magnetic Filaments SMF-1 to 4) As the soft magnetic filaments SMF-1 to 4, soft magnetic materials SM-1 to SM-4 were cut to a width of 1 mm and prepared.

[0073] (Investigation of properties of soft magnetic materials SM-1 to 4) The crystallization temperatures of the prepared SM-1 and 2 were measured using a differential thermal analyzer (Hitachi High-Tech Corporation, model: TG / DTA6200). The results are shown in Table 1 below.

[0074] Based on the results of the DTA measurements, SM-1 and SM-2 were heat-treated and the effect on Pi was investigated. Pi was also investigated for the prepared SM-3 and SM-4. Pi measurements were performed using a BH loop analyzer (IFG Corporation, IF-BH550) and the H coil method (compliant with JIS C 2556:2015) using a vertical yoke single sheet tester. Iron loss Pi under the conditions of magnetic flux density 1.0 T, frequency 400 Hz, and temperature 20°C -1.0 / 400(unit: W / kg) and iron loss Pi under the conditions of magnetic flux density 1.0 T, frequency 10000 Hz, and temperature 20°C -1.0 / 10k The results are shown in Table 1.

[0075]

[0076] As shown in Table 1, SM-1 has a first crystallization temperature of 533°C and a second crystallization temperature of 557°C. SM-2 has a first crystallization temperature of 395°C and a second crystallization temperature of 514°C. SM-1 and SM-2 exhibit very low Pi values ​​for heat treatment at a temperature (505°C) lower than the second crystallization temperature. -1.0 / 400 However, at 10000 Hz, Pi -1.0 / 10k It is confirmed that the Pi increases dramatically when heat treatment is performed at a temperature above the second crystallization temperature (700°C). -1.0 / 400 On the other hand, in SMF-3 and SMF-4, the Pi is sufficiently low at 400 Hz. -1.0 / 400 However, at 10000 Hz, Pi -1.0 / 10k is confirmed to increase dramatically.

[0077] [Experiment 2] (Preparation of Glass Compositions G-1 to G-3) Glass compositions G-1 to G-3 were prepared, each having the nominal composition shown in Table 2 below. The nominal compositions in the table are expressed as the mass ratio of each component converted to oxide. The starting materials used were V2O5 (Kojundo Chemical Laboratory Co., Ltd., purity 99.9%), P2O5 (Kojundo Chemical Laboratory Co., Ltd., purity 99.9%), BaCO3 (Kojundo Chemical Laboratory Co., Ltd., purity 99.9%), and Sb2O3 (Fujifilm Wako Pure Chemical Corporation, purity 99.9%). As can be seen from the purity of the starting materials, the lead-free glass composition used in the present invention contains a certain amount of unavoidable impurities.

[0078] The platinum crucible containing the mixed raw material powder was placed in a glass melting furnace and heated to 900°C at a heating rate of 5°C / min to melt the mixed raw material powder. The mixture was then held for 1 hour while stirring with an alumina rod to homogenize the composition of the melt in the platinum crucible. The platinum crucible was then removed from the glass melting furnace, and the melt was poured into a graphite mold preheated to 300°C to produce a bulk glass composition. The cast bulk was then transferred to a stress relief furnace preheated to a stress relief temperature, held for 1 hour to remove strain, and then cooled to room temperature at a rate of 1°C / min. The cooled bulk was pulverized using a stamp mill and a jet mill to prepare powders of lead-free glass compositions G-1 to G-3.

[0079] (Measurement of characteristic temperatures of glass compositions G-1 to G-3) The characteristic temperatures of G-1 to G-3 were measured using the same differential thermal analyzer as in Experiment 1. The measurement conditions were as follows: α-alumina as the standard sample, nitrogen as the measurement atmosphere, and a heating rate of 5°C / min. The measurement results of the softening points Ts are also shown in Table 2.

[0080]

[0081] As shown in Table 2, it has been confirmed that glass compositions with desirable characteristic temperatures can be obtained by controlling the constituent components and content of the glass. It has also been confirmed that the crystallization peak temperatures Tcp of G-1 to G-3 are each 45°C or more higher than Ts.

[0082] (Preparation of Glass Frits GF-1 to GF-9 and Investigation of Bulk Properties) The powders of G-1 to G-3 prepared above and a filler powder were mixed in the ratios shown in Table 3 below to prepare glass frits GF-1 to GF-9, which serve as the basis for the electrical insulating coating 2. Spherical SiO2 powder (average particle size 1 μm) was used as the filler powder.

[0083] Each of the prepared glass frits GF-1 to GF-9 was used to form a powder compact, which was then fired at a temperature 20°C higher than the Ts of the glass composition used to produce a bulk body corresponding to the electrical insulating coating 2. The bulk body was then ground into a prismatic shape (4 mm x 4 mm x 15 mm) to prepare a sample for measuring the linear expansion coefficient. The linear expansion coefficient of each sample was measured using a thermal dilatometer (ULVAC, Inc., Model DL-9600). The temperature range for measuring the linear expansion coefficient was from 30°C to the Tg of the glass composition. The results are also shown in Table 3.

[0084]

[0085] As shown in Table 3, it is confirmed that the linear expansion coefficient of the electrical insulating coating 2 can be controlled by mixing a filler into the glass composition.

[0086] (Preparation of glass pastes GP-1 to GP-9) 100 parts by mass of each of the glass frits GF-1 to GF-9 prepared in Experiment 2 was mixed with 10 parts by mass of nitrocellulose as a resin binder and 20 parts by mass of α-terpineol as a solvent to prepare glass pastes GP-1 to GP-9 for the soft magnetic composite wire 10.

[0087] [Experiment 3] (Preparation of soft magnetic composite plates SMCP-1r to 4r as reference samples) The glass paste GP-8 prepared in Experiment 2 was applied to both surfaces of the soft magnetic materials SM-1 to SM-4 prepared in Experiment 1 to form a soft magnetic composite plate precursor that served as an intermediate material. The soft magnetic composite plate precursor was then subjected to a predetermined heat treatment to form an electrical insulating coating 2, thereby preparing soft magnetic composite plates SMCP-1r to SMCP-4r as reference samples. The heat treatment pattern involved a drying process in which the plate was heated to 170°C and held for 30 minutes, followed by a firing process in which the plate was heated to a temperature 20°C higher than the Ts of the glass composition used and held for 30 minutes. The thickness of the electrical insulating coating 2 was controlled by controlling the thickness of the glass paste coating.

[0088] (Property investigation of soft magnetic composite plates SMCP-1r to 4r) For the manufactured SMCP-1r to 4r, iron loss Pi was measured in the same way as in Experiment 1. -1.0 / 400 and iron loss Pi -1.0 / 10kIn addition, the Pi in Table 1 was measured. -1.0 / 400 and Pi -1.0 / 10k The reduction rate (Pi reduction rate) was calculated from the measurement results.

[0089] Additionally, Pi -1.0 / 400 and Pi -1.0 / 10k After the measurement, the sample was cut and the Vickers hardness of the cross section of the soft magnetic material was measured using a nanoindentation tester (Elionix Co., Ltd., model ENT-1100a), and the amount of strain in the soft magnetic material was calculated. The results are shown in Table 4.

[0090]

[0091] As shown in Table 4 and Table 1, the soft magnetic composite material plates SMCP-1r to 4r, which are the reference samples, have a higher Pi than the soft magnetic materials SM-1 to SM-4. -1.0 / 400 and Pi -1.0 / 10k However, it can be seen that Pi of SMCP-1r to 4r has decreased. -1.0 / 10k The rate of decrease is Pi -1.0 / 400 It can be seen that this is small compared to the rate of decrease.

[0092] [Experiment 4] (Preparation of soft magnetic composite wire) The glass pastes GP-1 to GP-9 prepared in Experiment 2 were applied to both surfaces of the soft magnetic filaments SMF-1 to 4 prepared in Experiment 1 to form soft magnetic composite wire precursors as intermediate materials, and then the soft magnetic composite wire precursors were subjected to a predetermined heat treatment to form an electrical insulating coating 2, thereby preparing soft magnetic composite wires. The heat treatment pattern was the same as in Experiment 3, except that the drying process was omitted. Furthermore, the thickness of the electrical insulating coating 2 was controlled by controlling the thickness of the glass paste coating film, as in Experiment 3.

[0093] (Production of soft magnetic composite plates SMCP-1i to 20i of the present invention) The prepared soft magnetic composite wires were bundled and arranged into a plate shape (70 mm long, 70 mm wide). At this time, the soft magnetic composite wires were arranged so that their longitudinal directions were all aligned (parallel). The plate-shaped samples were then subjected to a specified heat treatment while being pressed to a thickness of 300 μm, causing the electrical insulating coating 2 to soften, flow, and harden again, resulting in an integrated molding. The heat treatment pattern was the same as in Experiment 3, except that the drying process was omitted.

[0094] Next, the integrally molded plate-shaped sample was cut parallel to the longitudinal direction of the arranged soft magnetic composite wires to produce soft magnetic composite material plates SMCP-1i to 20i of the present invention (length 70 mm, width 20 mm, thickness 300 μm, the longitudinal direction of the sample plate and the longitudinal direction of the soft magnetic composite wires were parallel).

[0095] (Property investigation of soft magnetic composite material plates SMCP-1i to 20i) The properties of the manufactured SMCP-1i to 20i were investigated in the same manner as in Experiment 3. In the Pi measurement, the applied magnetic field was adjusted to be parallel to the longitudinal direction of the sample plate (the magnetization direction was parallel to the longitudinal direction of the soft magnetic composite wire). The results are shown in Table 5.

[0096]

[0097] As shown in Tables 5 and 4, the soft magnetic composite plates SMCP-1i to 20i of the present invention have Pi values ​​equal to or higher than those of the reference samples SMCP-1r to 4r. -1.0 / 400 The Pi decreases by a much larger rate than that of SMCP-1r to 4r. -1.0 / 10k This is thought to be due to a combination of a reduction in hysteresis loss due to the application of tensile strain to the soft magnetic filaments and a reduction in eddy current loss due to filamentization (reduction in the eddy current area).

[0098] [Experiment 5] (Preparation of comparative soft magnetic composite plates SMCP-1c to 4c) The plate-shaped samples (length 70 mm, width 70 mm) integrally molded in Experiment 4 were cut perpendicular to the longitudinal direction of the arranged soft magnetic composite wires to prepare comparative soft magnetic composite plates SMCP-1c to 4c (length 70 mm, width 20 mm, thickness 300 μm, the longitudinal direction of the sample plate was perpendicular to the longitudinal direction of the soft magnetic composite wires).

[0099] (Property investigation of soft magnetic composite material plates SMCP-1c to 4c) The properties of the manufactured SMCP-1i to 20i were investigated in the same manner as in Experiment 3. In the Pi measurement, the applied magnetic field was adjusted to be parallel to the longitudinal direction of the sample plate (the magnetization direction was perpendicular to the longitudinal direction of the soft magnetic composite wire). The results are shown in Table 6.

[0100]

[0101] As shown in Table 6 and Table 1, the soft magnetic composite material plates SMCP-1c to SMCP-4c, which are comparative samples, have a higher Pi value than the soft magnetic materials SM-1 to SM-4. -1.0 / 400 and Pi -1.0 / 10k It can be seen that Pi is increasing. -1.0 / 400 Decrease rate and Pi -1.0 / 10k Pi, not the rate of decrease -1.0 / 400 Growth rate and Pi -1.0 / 10k From this result, it can be said that in a soft magnetic composite plate, it is desirable to align the magnetization direction with the longitudinal direction of the soft magnetic composite wire (the longitudinal direction of the soft magnetic filament).

[0102] The above-described embodiments and experiments have been described to aid in understanding the present invention, and the present invention is not limited to the specific configurations described. For example, it is possible to replace part of the configuration of the embodiments with configurations that are within the technical common sense of those skilled in the art, and it is also possible to add configurations that are within the technical common sense of those skilled in the art to the configuration of the embodiments. In other words, it is possible to delete, replace, or add part of the configurations of the embodiments and experiments in this specification, as long as they do not deviate from the technical concept of the invention.

[0103] 1...soft magnetic filament, 2...electrical insulating coating, 10...soft magnetic composite wire, 20...soft magnetic composite material plate, 30...iron core, 31...stator slot, 32...slit, 33...teeth, 34...teeth claw portion, 35...yoke portion, 40...stator, 41...stator coil, 42...segment conductor, 43...electrical insulating material.

Claims

1. A soft magnetic composite plate comprising a soft magnetic material and an electrically insulating coating, wherein the soft magnetic material has a filament shape, the electrically insulating coating contains a lead-free glass composition and has a linear expansion coefficient that is at least 3 ppm / K smaller than that of the soft magnetic material, and the electrically insulating coating forms a soft magnetic composite wire on the surface of the filament-shaped soft magnetic material, and the soft magnetic composite wires are integrated so that their longitudinal directions are aligned in the in-plane direction of the plate shape of the soft magnetic composite plate.

2. A soft magnetic composite plate according to claim 1, characterized in that the thickness of the soft magnetic composite plate is 0.01 mm or more and 3 mm or less, the space factor of the soft magnetic material is 80 volume % or more, and the average thickness of the electrical insulating coating is less than 10% of the diameter of a circle having an equivalent area of ​​the cross section of the filament shape.

3. A soft magnetic composite plate according to claim 1, wherein the glass composition, when expressed as nominal components in terms of oxides, contains 40% by mass or more and 70% by mass or less of V2O5 and 10% by mass or more and 35% by mass or less of P2O5, the sum of the V2O5 and the P2O5 being 50% by mass or more and 98% by mass or less, the glass composition contains two or more elements selected from the group consisting of BaO, Sb2O3, WO3, ZnO, K2O, Fe2O3, TeO2, Ag2O, and Li2O in a total amount of 2% by mass or more and 50% by mass or less, and the remainder being unavoidable impurities, and the softening point of the glass composition is 500°C or less.

4. A soft magnetic composite plate according to claim 2, wherein the glass composition, when expressed as nominal components in terms of oxides, contains 40% by mass or more and 70% by mass or less of V2O5 and 10% by mass or more and 35% by mass or less of P2O5, the sum of the V2O5 and the P2O5 being 50% by mass or more and 98% by mass or less, the glass composition contains two or more elements selected from the group consisting of BaO, Sb2O3, WO3, ZnO, K2O, Fe2O3, TeO2, Ag2O, and Li2O in a total amount of 2% by mass or more and 50% by mass or less, and the remainder being unavoidable impurities, and the softening point of the glass composition is 500°C or less.

5. A soft magnetic composite plate according to claim 3, wherein the electrically insulating coating contains 75% by volume or less of a filler of oxide particles, and the filler is one or more selected from the group consisting of SiO2, ZrO2, Al2O3, Nb2O5, ZrSiO4, Zr2(WO4)(PO4)2, 2MgO.2Al2O3.5SiO2, 3Al2O3.2SiO2, and LiAlSiO4.

6. A soft magnetic composite plate according to claim 4, wherein the electrically insulating coating contains 75% by volume or less of a filler of oxide particles, and the filler is one or more selected from the group consisting of SiO2, ZrO2, Al2O3, Nb2O5, ZrSiO4, Zr2(WO4)(PO4)2, 2MgO.2Al2O3.5SiO2, 3Al2O3.2SiO2, and LiAlSiO4.

7. A soft magnetic composite plate according to claim 5, wherein the coefficient of linear expansion of the electrically insulating coating is less than 10 ppm / °C.

8. A soft magnetic composite plate according to claim 6, wherein the coefficient of linear expansion of the electrically insulating coating is less than 10 ppm / °C.

9. A soft magnetic composite plate according to any one of claims 1 to 8, characterized in that the soft magnetic material has a tensile strain in the range of 10 μST to 1000 μST along its longitudinal direction.

10. A soft magnetic composite plate according to any one of claims 1 to 8, characterized in that the soft magnetic composite plate has a tensile strain in the range of 10 μST or more and 1000 μST or less along its in-plane direction.

11. An iron core comprising a laminate of soft magnetic composite plates, wherein the soft magnetic composite plates are soft magnetic composite plates as defined in any one of claims 1 to 8, and the soft magnetic materials are arranged so that the longitudinal direction of the wire-shaped soft magnetic material is parallel to the magnetization direction applied to the soft magnetic composite plates.

12. An iron core made of a laminate of soft magnetic composite plates, wherein the soft magnetic composite plates are the soft magnetic composite plates described in claim 9, and the soft magnetic materials are arranged so that the longitudinal direction of the wire-shaped soft magnetic material is parallel to the magnetization direction applied to the soft magnetic composite plates.

13. An iron core comprising a laminate of soft magnetic composite plates, wherein the soft magnetic composite plates are the soft magnetic composite plates described in claim 10, and the soft magnetic materials are arranged so that the longitudinal direction of the wire-shaped soft magnetic material is parallel to the magnetization direction applied to the soft magnetic composite plates.

14. A rotating electric machine having an iron core, characterized in that the iron core is the iron core according to claim 11.

15. A rotating electric machine having an iron core, characterized in that the iron core is the iron core according to claim 12.

16. A rotating electric machine having an iron core, characterized in that the iron core is the iron core according to claim 13.

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