Laminated magnet and motor

Abstract

The present invention provides a novel laminated magnet in which eddy current loss generated inside can be reduced and which is excellent in magnetic characteristics.　A laminated magnet (10) is formed by laminating a plurality of magnets (11) and an insulating layer (13) in a first direction. The magnets (11) contain a rare earth element. The total amount of rare earth element in the magnets (11) is 27 mass% or more and 31.0 mass% or less. The dielectric constant of the laminated magnet (10) at 1 kHz in the first direction is 1.0-5.0.

Description

Laminated magnet and motor

[0001] The present disclosure relates to laminated magnets and motors.

[0002] Patent Document 1 discloses a rare earth magnet with a resistive layer formed on the surface of the magnet body. It also shows a laminated magnet in which multiple rare earth magnets are stacked and molded with resin. Various magnets have also been proposed with the aim of reducing eddy current loss (e.g., Patent Documents 2 to 4).

[0003] JP 2017-174962 A JP 2013-219911 A JP 2007-157903 A JP 2003-164083 A

[0004] In recent years, there have been various demands for laminated magnets. For example, there is a demand for a new laminated magnet that can reduce eddy current loss generated inside and has excellent magnetic properties. The present disclosure has been made in consideration of the above-mentioned circumstances, and aims to provide a new laminated magnet that can reduce eddy current loss generated inside and has excellent magnetic properties. The present disclosure can be realized in the following forms.

[0005] [1] A laminated magnet in which a plurality of magnets and insulating layers are stacked in a first direction, the magnets contain rare earth elements, the total amount of rare earth elements in the magnets is 27% by mass or more and 31.0% by mass or less, and the dielectric constant of the laminated magnet at 1 kHz in the first direction is 1.0 or more and 5.0 or less.

[0006] According to the present disclosure, it is possible to provide a novel laminated magnet that can reduce eddy current loss generated inside and has excellent magnetic properties.

[0007] 6 is a perspective view schematically showing an example of a laminated magnet. FIG. 7 is a top view of the laminated magnet. FIG. 8 is a cross-sectional view taken along line A-A in FIG. 2. FIG. 9 is an enlarged view showing a portion of FIG. 3. FIG. 10 is a diagram for explaining a method for measuring the average degree of orientation of magnets in Alternative Example 1. FIG. 11 is a cross-sectional view of Alternative Example 1 of the laminated magnet. FIG. 12 is an enlarged view showing a portion of FIG. 13. FIG. 14 is a perspective view schematically showing Alternative Example 2 of the laminated magnet. FIG. 15 is a diagram for explaining a method for measuring the average degree of orientation of magnets in Alternative Example 2. FIG. 16 is a cross-sectional view schematically showing a portion of a motor. FIG. 17 is a plan view of a rotor.

[0008] Hereinafter, preferred examples of the present disclosure will be described. [2] The magnet laminate according to [1], wherein the insulating layer is primarily composed of inorganic crystals. [3] The magnet laminate according to [2], wherein the inorganic crystals include at least one type of Group 2A fluoride of the periodic table. [4] The magnet laminate according to any one of [1] to [3], wherein a surface coating layer of rare earth nitride is present. [5] The magnet laminate according to [4], wherein the magnets have an average degree of orientation of 97.0% or more. [6] The magnet laminate according to any one of [1] to [3], wherein the magnets have an average degree of orientation of 97.0% or more. [7] A motor comprising the magnet laminate according to any one of [1] to [6].

[0009] The present disclosure will be described in detail below. In this specification, when a numerical range is indicated using "-", it is assumed that both the lower limit and the upper limit are included unless otherwise specified. For example, the expression "10-20" includes both the lower limit of "10" and the upper limit of "20". In other words, "10-20" has the same meaning as "10 or more and 20 or less". In this specification, the upper and lower limit values ​​of each numerical range can be arbitrarily combined. Hereinafter, the Z-axis direction in each figure is the stacking direction (first direction) of the magnet laminate 10. One direction perpendicular to the Z-axis direction is referred to as the X-axis direction (also referred to as the second direction), and the direction perpendicular to the Z-axis direction and the X-axis direction is referred to as the Y-axis direction.

[0010] 1. Magnet Laminate 10 As shown in Figures 1 to 3, magnet laminate 10 is a magnet laminate in which multiple magnets 11 and insulating layers 13 are stacked in a first direction. Magnet 11 contains rare earth elements. The total amount of rare earth elements in magnet 11 is 27% by mass or more and 31.0% by mass or less. The permittivity of magnet laminate 10 at 1 kHz in the first direction is 1.0 or more and 5.0 or less.

[0011] (1) Magnet 11 The magnet 11 is a permanent magnet containing a rare earth element. From the viewpoint of having good magnetic properties, the magnet 11 is preferably a rare earth sintered magnet.

[0012] The composition of magnet 11 is not particularly limited as long as it contains rare earth elements. From the viewpoint of increasing magnetic flux density, the total amount of rare earth elements in magnet 11 is 31.0 mass% or less, and preferably 29.5 mass% or less. The lower limit of the total amount of rare earth elements in magnet 11 is 27 mass% or more, and may be, for example, 28 mass% or more, or 28.5 mass% or more. The total amount of rare earth elements in magnet 11 can be measured by X-ray fluorescence analysis. The total amount of rare earth elements can be adjusted by changing the content of rare earth elements in the raw materials of magnet 11 and insulating layer 13.

[0013] The magnet 11 may be, for example, a magnet containing a rare earth element (R), a transition metal element (T), and boron (B). Such a magnet is also called an RTB magnet.

[0014] Examples of rare earth elements include one or more selected from the group consisting of neodymium (Nd), praseodymium (Pr), terbium (Tb), dysprosium (Dy), samarium (Sm), yttrium (Y), scandium (Sc), lanthanum (La), cerium (Ce), europium (Eu), gadolinium (Gd), holmium (Ho), ytterbium (Yb), and lutetium (Lu). Among these, the rare earth element preferably includes one or more of Nd, Pr, Dy, and Tb, and more preferably includes Nd as the primary component. Note that "primarily Nd" means that the Nd content (mass%) is the highest among the rare earth elements. The B content is preferably 0.1% to 3% by mass of the entire magnet 11, and more preferably 0.5% to 1.5% by mass.

[0015] Examples of transition metal elements include one or more selected from the group consisting of iron (Fe), cobalt (Co), and nickel (Ni). Among these, from the viewpoint of magnetic properties, it is preferable to include one or more of Fe and Co as the transition metal element, and it is more preferable to include Fe as the main component. Incidentally, "Fe as the main component" means that the content (mass %) of Fe is the highest among the transition metal elements. The content of the transition metal element is preferably 60 mass % or more of the entire magnet 11, more preferably 65 mass % or more. The upper limit of the transition metal element is not particularly limited, and can be, for example, 73 mass % or less of the entire magnet 11. Furthermore, when Fe and Co are included, a portion of the Fe may be substituted with Co. For example, when the total of Fe and Co is 100 mass %, the content of Co can be greater than 0 mass % and less than 1 mass %.

[0016] Magnet 11 may contain elements other than those listed above (hereinafter also referred to as "other elements"). Examples of other elements include one or more selected from the group consisting of aluminum (Al), copper (Cu), zinc (Zn), indium (In), silicon (Si), phosphorus (P), sulfur (S), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), nickel (Ni), gallium (Ga), germanium (Ge), zirconium (Zr), niobium (Nb), molybdenum (Mo), palladium (Pd), silver (Ag), cadmium (Cd), tin (Sn), antimony (Sb), hafnium (Hf), tantalum (Ta), and tungsten (W). The content of other elements is preferably 0% to 3% by mass of the entire magnet 11.

[0017] From the viewpoint of improving coercivity, it is more preferable that magnet 11 have a region in which the concentration of heavy rare earth elements decreases from at least a portion of the surface of magnet 11 toward the interior of magnet 11. In FIGS. 4 and 7 , the decrease in concentration of heavy rare earth elements is represented by the shade of the shading. Areas with high concentrations of heavy rare earth elements are shown with dark shading, while areas with low concentrations are shown with light shading. A configuration having a region in which the concentration of heavy rare earth elements decreases can contribute to reducing the amount of heavy rare earth elements added while maintaining magnetic properties. The heavy rare earth elements can be one or more selected from the group consisting of terbium (Tb), dysprosium (Dy), gadolinium (Gd), holmium (Ho), europium (Eu), thulium (Tm), ytterbium (Yb), and lutetium (Lu). Of these, the heavy rare earth elements are preferably one or more of Dy and Tb. The region in magnet 11 where the concentration of the heavy rare earth element is reduced can be formed, for example, by applying a material containing the heavy rare earth element to the surface of magnet 11 and then heat treating it. Details will be explained later.

[0018] The magnet 11 is, for example, Nd ２ Fe １４ Preferably, the magnet 11 has a main phase of B and a rare earth-rich phase that has a higher rare earth element content than the main phase. The magnet 11 may also have a boron-rich phase that has a higher boron content than the main phase. The main phase usually has a tetragonal crystal structure. For example, the above-mentioned Nd ２ Fe １４ B has a tetragonal crystal structure. The main phase of the magnet 11 can be identified by X-ray diffraction (XRD) analysis of the magnet 11 as the component with the largest peak intensity. ２ Fe １４ When the peak intensity of B is the largest, the magnet 11 is Nd ２ Fe １４ It can be determined that the main phase is B.

[0019] The shape of the magnet 11 is not particularly limited. Preferably, the magnet 11 is, for example, plate-shaped. Plate-shaped magnets 11 have a shorter distance from the surface to the deepest part than thicker block-shaped magnets. Therefore, plate-shaped magnets 11 are suitable because they facilitate the diffusion of heavy rare earth elements into the interior when grain boundary diffusion occurs. Plate-shaped magnets 11 can be suitably used as a laminated magnet in which multiple magnets 11 and insulating layers 13 are stacked. The laminated magnet 10 of FIG. 1 has multiple magnets 11 stacked with the thickness direction of the plate-shaped magnets 11 as the stacking direction. In this laminated magnet 10, the magnets 11 and insulating layers 13 are alternately stacked. In a laminated magnet, each magnet 11 is sometimes referred to as a magnet body. The magnets 11 in FIGS. 1 and 2 are rectangular when viewed from above (Z-axis direction). The magnet 11 may have a shape other than rectangular when viewed from above, and may, for example, have a curved shape (such as a circular arc) that is convex in one direction when viewed from above (the positive direction in the X-axis direction in FIG. 8, or the upward direction in FIG. 9) as shown in FIGS. 8 and 9.

[0020] The thickness of magnet 11 is preferably 0.5 mm or more and 4.0 mm or less, and more preferably 1.2 mm or more and 2.5 mm or less. If magnet 11 is 0.5 mm or more thick, it is easy to form magnet 11 while ensuring an average degree of orientation. If magnet 11 is 4.0 mm or less thick, it is easy to diffuse the heavy rare earth element deep into the magnet laminate 10. Furthermore, if the thickness is 4.0 mm or less, eddy current loss inside magnet laminate 10 can be suitably reduced. The dimensions of plate-shaped magnet 11 in the direction perpendicular to the thickness are not particularly limited. For example, magnet 11 can have a thickness of 0.5 mm or more and 4.0 mm or less, or 4 mm or more and 10 mm or less, and a width of 10 mm or more and 30 mm or less.

[0021] (2) Insulating Layer 13 The insulating layer 13 is not particularly limited. For example, inorganic insulating materials such as inorganic crystals or organic insulating materials such as resins can be used as the insulating layer 13. The insulating layer 13 is preferably composed primarily of inorganic crystals. The inorganic crystals are more preferably non-magnetic crystalline particles. The term "composed primarily of inorganic crystals" means that the content of inorganic crystals in the insulating layer 13 is 50% by mass or more. The content of inorganic crystals in the insulating layer 13 is preferably 80% by mass or more, more preferably 90% by mass or more, and may be 100% by mass. The composition of the insulating layer 13 can be analyzed by the following method. When the insulating layer 13 is composed primarily of an inorganic insulating material, the presence of inorganic crystals can be determined by X-ray microanalysis or XRD analysis, and the content of inorganic crystals can be calculated by combining this with composition analysis by EPMA. When the insulating layer 13 is mainly composed of an organic insulating material, it can be analyzed by NMR (Nuclear Magnetic Resonance) and IR (Infrared Absorption Spectrometry) analysis.

[0022] The insulating layer 13 is made of inorganic crystals such as CaF ２ , BaF ２ , SrF ２ , MgF ２ , Al ２ O ３ , ZrO ２ , Dy ２ O ３ , Tb ２ O ３ , Nd ２ O ３ , TbF ３ , DyF ３ , LiF, SiO ２ , BN, ZrB ２ , Si ３ N ４ , TiB ２ , Pr ２ O ３ From the viewpoint of reducing eddy current loss, the insulating layer 13 preferably contains at least a fluoride of Group 2A of the periodic table as an inorganic crystal. The insulating layer 13 preferably contains CaF as the fluoride of Group 2A of the periodic table.２ , BaF ２ , SrF ２ , and MgF ２ It is more preferable that the insulating layer 13 contains at least one selected from the group consisting of CaF ２ It is particularly preferred that the composition contains:

[0023] When the total mass of the inorganic crystals is taken as 100 mass %, the insulating layer 13 preferably contains 80 mass % or more, more preferably 90 mass % or more, and even more preferably 95 mass % or more of a fluoride of Group 2A of the periodic table as the inorganic crystals. The upper limit of the content of the fluoride of Group 2A of the periodic table is not particularly limited, and may be, for example, 100 mass %.

[0024] When the insulating layer 13 is primarily composed of a Group 2A fluoride, the raw material for the insulating layer 13 preferably contains the above-mentioned heavy rare earth element compound in addition to the Group 2A fluoride. If the raw material for the insulating layer 13 contains the above-mentioned heavy rare earth element compound, the heavy rare earth element can be favorably diffused into the magnet 11. The heavy rare earth element contained in the raw material for the insulating layer 13 diffuses into the magnet 11 after heat treatment. Therefore, the insulating layer 13 of the resulting magnet laminate 10 contains almost no heavy rare earth element. The mass ratio of the Group 2A fluoride to the heavy rare earth element compound in the raw material for the insulating layer 13 is not particularly limited. The mass ratio of the Group 2A fluoride to the heavy rare earth element compound in the raw material for the insulating layer 13 can be, for example, 20:80-40:60.

[0025] The insulating layer 13 only needs to be present between the magnets 11, 11. The insulating layer 13 may be arranged, for example, as follows: The insulating layer 13 may be arranged so as to cover the entire surface of the magnet 11 (see FIG. 6). In the example of FIG. 6, both the upper and lower main surfaces 11A and both side surfaces 11B of each magnet 11 are covered with the insulating layer 13, and the insulating layer 13 is arranged so as to cover the entire surface of the magnet 11. The insulating layer 13 may be arranged so as to cover only a portion of the surface of the magnet 11 (see FIG. 3). In the example of FIG. 3, the side surfaces 11B of each magnet 11 are not covered with the insulating layer 13, and the insulating layer 13 is arranged so as to cover only a portion of the surface of the magnet 11. 3, the topmost magnet 11 has one (lower) main surface 11A covered with insulating layer 13, but the other (upper) main surface 11A is not covered with insulating layer 13, and insulating layer 13 is arranged to cover part of the surface of magnet 11. Similarly, in the example of FIG. 3, the bottommost magnet 11 has one (upper) main surface 11A covered with insulating layer 13, but the other (lower) main surface 11A is not covered with insulating layer 13, and insulating layer 13 is arranged to cover part of the surface of magnet 11.

[0026] The insulating layer 13 is preferably provided so as to be in direct contact with the magnet 11. The insulating layer 13 may also be an insulating bonding layer that bonds (adheses) the magnets 11, 11 located on both sides. From the viewpoint of bonding the magnets 11, 11 with sufficient strength, the insulating layer 13 preferably has a region in the direction in which the multiple magnets 11 are arranged (the Z-axis direction) where components derived from the insulating layer 13 and components derived from the magnet 11 are mixed. Such a magnet stack 10 can be suitably formed by hot pressing. The conditions for hot pressing will be explained later.

[0027] The insulating layers 13 may be provided along the orientation direction of the magnetic field of each magnet 11 (e.g., the X-axis direction in FIG. 3 , the direction of the white arrow in FIG. 3 ), or along a direction intersecting the orientation direction (e.g., the X-axis direction in FIG. 3 ) (e.g., the Z-axis direction in FIG. 3 ). Note that, as shown in FIG. 11 , when the magnet stack 10 is used as a motor magnet or the like, the insulating layers 13 are preferably provided along the orientation direction of the magnets 11 (the X-axis direction in FIG. 11 ) from the perspective of efficiently reducing eddy current loss. With this configuration, the insulating layers 13 are arranged approximately parallel to the direction in which the magnetic flux generated in the stator 31 passes through the magnet stack 10 (the X-axis direction in FIG. 11 ), thereby effectively reducing eddy current loss.

[0028] The thickness T of the insulating layer 13 is not particularly limited. From the viewpoint of ensuring sufficient insulation, the thickness T of the insulating layer 13 is preferably 5 μm or more, more preferably 9 μm or more, and even more preferably 12 μm or more. From the viewpoint of ensuring magnetic properties, the thickness T of the insulating layer 13 is preferably 30 μm or less, more preferably 25 μm or less, and even more preferably 18 μm or less. From these viewpoints, the thickness T of the insulating layer 13 is preferably 5 μm or more and 30 μm or less, more preferably 9 μm or more and 25 μm or less, and even more preferably 12 μm or more and 18 μm or less. The thickness T of the insulating layer 13 is measured, for example, by observing the cross section of the magnet laminate 10 with a scanning electron microscope (SEM) and measuring the distance between the magnets 11 located on both sides of the insulating layer 13 (see FIGS. 4 and 7 ).

[0029] (3) Configuration of the magnet stack 10 From the viewpoint of reducing eddy current loss, it is preferable that 10 or more magnets 11 are used per 50 mm of dimension of the magnet stack 10 in the first direction, preferably 20 or more magnets, and preferably 25 or more magnets. There is no particular upper limit on the number of magnets, and it may be, for example, 35 or less.

[0030] (4) Requirements for Dielectric Constant The dielectric constant of the magnet laminate 10 at 1 kHz in the first direction is 1.0 or more and 5.0 or less. A dielectric constant within this range is suitable for various applications, such as motors. The upper limit of the dielectric constant may be 4.5 or less, or 4.2 or less, from the viewpoint of maintaining a suitable impedance of the magnet laminate 10. The lower limit of the dielectric constant may be 2.0 or more, 2.5 or more, or 3.0 or more. The dielectric constant can be controlled by the dielectric constant of the insulating layer 13 itself, the number of divisions of the magnet laminate 10 (the number of insulating layers 13), etc. For example, using insulating layers 13 with a high dielectric constant tends to increase the dielectric constant, while using insulating layers 13 with a low dielectric constant tends to decrease the dielectric constant. Furthermore, increasing the number of insulating layers 13 increases the dielectric constant, while decreasing the number of insulating layers 13 tends to decrease the dielectric constant. Furthermore, increasing the temperature and pressure in the hot pressing process described below tends to thicken the surface coating layer 15 and increase the dielectric constant.

[0031] (5) Rare Earth Nitride Surface Coating Layer 15 The magnet laminate 10 preferably has a rare earth nitride surface coating layer 15 from the viewpoints of improving the strength of the magnet 11 and suppressing deterioration due to oxygen. Examples of rare earth nitrides include one or more selected from the group consisting of NdN, TbN, and DyN. The state of the surface coating layer 15 can be confirmed by observing the cross section of the magnet laminate 10 with an FE-SEM.

[0032] The rare earth nitride surface coating layer 15 can be formed, for example, by nitriding the rare earth elements contained in the rare earth-rich phase that has flowed out to the surface of the magnet 11. The lower the total amount of rare earth elements in the magnet 11, the less likely such rare earth-rich phases tend to flow out to the surface of the magnet 11. The present inventors have newly discovered that the rare earth nitride surface coating layer 15 can be formed by hot pressing even in magnet laminates 10 that use magnets 11 with a total rare earth element amount of 31.0 mass% or less, and have developed the technology of the present disclosure. The method of forming the rare earth nitride surface coating layer 15 by hot pressing will be described later.

[0033] The thickness of the surface coating layer 15 is not particularly limited. From the viewpoint of improving the strength of the magnet 11 and suppressing deterioration due to oxygen, the thickness of the surface coating layer 15 is preferably 2 μm or more, more preferably 3.5 μm or more, and even more preferably 5 μm or more. There is no particular upper limit to the thickness of the surface coating layer 15, and it is usually 10 μm or less. The thickness of the surface coating layer 15 can be measured, for example, by observing the cross section of the magnet laminate 10 with an FE-SEM.

[0034] (6) Average Orientation of Magnet 11 The average orientation of magnet 11 is preferably 90% or more, more preferably 95% or more, even more preferably 97.0% or more, and particularly preferably 98.0% or more. The higher the average orientation of magnet 11, the better, but it is usually 99.5% or less. In Figures 2 and 3, the white arrows indicate the orientation direction. Multiple magnets 11 can be used, for example, lined up in a direction perpendicular to the orientation direction, as shown in Figure 3.

[0035] The average orientation of magnet 11 can be determined, for example, as follows. If magnet 11 is rectangular (quadrature) as shown in Figures 1 and 5, it is cut out to a size compatible with the measuring device and measured. For example, on the rectangular base of magnet 11 in Figure 5, the average orientation is determined as the average orientation of each 1 mm wide section centered on the normal Nn at multiple points Pn from one end of the long side to the other. The number of multiple points Pn is not particularly limited. Figure 5 shows five points P1-P5 and normals N1-N5 at each of points P1-P5. If the size of magnet 11 is sufficiently small, the number of multiple points Pn may be two, but five or more is preferable. The number of multiple points Pn is usually 10 or less. For example, a pulsed high magnetic field measuring device (magnetic field: 4 T) can be used as the measuring device. If the cut-out portion does not fit into the measuring device, a sample of a size that can fit into the measuring device is cut out from the center of the cut-out portion.

[0036] When the magnet 11 has a convex curved shape, as shown in Figures 8 and 9, the average orientation is calculated as the average degree of orientation of each 1 mm wide portion centered on the normal Nn at multiple points Pn from one end to the other on the convex side curve C1 on the outer periphery of the magnet 11 as viewed from the first direction (Z-axis direction). The number of points Pn is not particularly limited. When the size of the magnet 11 is sufficiently small, the number of points Pn may be two, but five or more is preferable. The number of points Pn is usually 10 or less. Note that when the magnet 11 has a convex curved shape, the radius of curvature of the curve C1 is not limited to a constant value and may vary.

[0037] Below, a method for calculating the average degree of orientation when magnet 11 has a convex curved shape will be described in detail with reference to Figures 9 and 10. When viewed from the Z-axis direction, the curve on the convex side of the periphery of magnet 11 is designated as curve C1, and the line tracing the edge opposite curve C1 is designated as opposing line C2. First, as shown in Figure 9, multiple points Pn are identified. In this embodiment, five points P1-P5 are identified. On magnet 11, points P1 and P5 at both ends of curve C1 on the convex side are located within 5 mm of one end (e.g., the left end) and within 5 mm of the other end (e.g., the right end). Multiple points (points P2-P4 in this embodiment) are located at equal intervals (four equal positions in this embodiment) between points P1 and P5 at both ends of curve C1, starting from one end. In this embodiment, point P3 is located in the middle of curve C1.

[0038] On the curve C1, the normal lines N1-N5 at each point P1-P5 are identified. A 1 mm wide portion 12 is cut out from the magnet 11, centered on the normal line Nn. Each portion 12 is, for example, approximately rectangular prism-shaped, as shown in FIG. 10. In reality, the top and bottom surfaces of FIG. 10 are curved surfaces. The degree of orientation of each portion 12 is measured, for example, using a pulsed high magnetic field measuring device (magnetic field: 4 T). If the cut-out portion does not fit into the measuring device, a sample of a size that can fit into the measuring device is cut out from the center of the cut-out portion. The average value of the degrees of orientation of each portion 12 is calculated as the average degree of orientation.

[0039] The average degree of orientation of magnet 11 can be controlled, for example, by appropriately designing the magnetic field to be applied in the orientation process described below. For example, even if magnet 11 has a convex curved shape, the above-mentioned average degree of orientation of 90% or more can be achieved by applying a magnetic field that extends in the normal direction of curve C1 of magnet 11 in the orientation process described below.

[0040] (7) Requirements for the aspect ratio and average particle size of the main phase particles of magnet 11 The average aspect ratio of the main phase particles of magnet 11 is preferably 2 or more and 4 or less. The average particle size of the main phase particles is preferably 1.5 μm or more and 4.0 μm or less. Within these ranges, the packing of the main phase particles is improved, and the magnetic permeability of magnet 11 can be improved. The average aspect ratio may be 2.3 or more and 4 or less, or 2.5 or more and 4 or less. The average particle size may be 1.8 μm or more and 3.5 μm or less, or 2.0 μm or more and 3.0 μm or less.

[0041] The average aspect ratio of the main phase grains of magnet 11 is determined by observing a cross section of magnet laminate 10 along the first direction with a field emission scanning electron microscope (FE-SEM). Specifically, a square field of view of 200 μm × 200 μm is observed using the FE-SEM. Note that the observed main phase grains do not include main phase grains that are partially missing from the field of view. The aspect ratios of all observed main phase grains are measured by image analysis. The average of the measured aspect ratios is defined as the average aspect ratio. The average aspect ratio can be controlled by changing the conditions of the hot pressing process in the manufacturing method of magnet laminate 10 described below. For example, increasing the hot pressing pressure tends to increase the average aspect ratio, while decreasing the hot pressing pressure tends to decrease the average aspect ratio.

[0042] The average grain size of the main phase particles of magnet 11 is determined by observing a cross section of magnet laminate 10 taken along the first direction with an FE-SEM (field emission scanning electron microscope). Specifically, a square field of view of 200 μm × 200 μm is observed using the FE-SEM. Note that the observed main phase particles do not include main phase particles that are partially missing from the field of view. The equivalent area circle diameter is calculated for all observed main phase particles by image analysis. The average value of the calculated equivalent area circle diameters is taken as the average grain size. The above average grain size can be controlled by adjusting the average grain size D50 of the SC alloy powder obtained by the pulverization process in the manufacturing method of magnet laminate 10 described below.

[0043] (8) Requirements for the Porosity of Magnet 11 The porosity of magnet 11 is preferably 3% or less. Within this range, the packing of the main phase particles is improved, and the magnetic permeability of magnet 11 can be improved. The porosity is more preferably 2.5 or less, even more preferably 1.5 or less, and particularly preferably 1.2 or less. The lower limit of the porosity may be 0%, and is usually 0.1% or more.

[0044] The porosity of the magnet 11 is determined by observing a cross section of the magnet laminate 10 along the first direction using a field emission scanning electron microscope (FE-SEM). Specifically, three 500 μm × 500 μm square fields of view are observed using the FE-SEM. For each field of view, the area ratio of pores to the entire field of view is calculated using image analysis. The average of the calculated pore area ratios is taken as the porosity. The porosity can be controlled by changing the average particle size D50 of the SC alloy powder obtained in the pulverization process or the conditions of the hot pressing process in the manufacturing method of the magnet laminate 10 described below. For example, decreasing the average particle size D50 of the SC alloy powder tends to decrease the porosity. Increasing the average particle size D50 of the SC alloy powder tends to increase the porosity. Furthermore, increasing the hot pressing pressure tends to increase the average aspect ratio, while decreasing the hot pressing pressure tends to decrease the average aspect ratio.

[0045] 2. Manufacturing Method of the Magnet Laminate 10 There are no particular limitations on the manufacturing method of the magnet laminate 10. An example of a manufacturing method of the magnet laminate 10 in which magnets 11 and insulating layers 13 are alternately stacked is shown below.

[0046] (1) SC Alloy Preparation Step A raw alloy (strip cast alloy (SC alloy)) containing rare earth elements, transition metal elements, boron, and the like is prepared.

[0047] (2) Hydrogen decomposition process: In a hydrogen atmosphere, the SC alloy is allowed to absorb hydrogen at a predetermined temperature (e.g., 200°C) for a predetermined time (e.g., 1 to 5 hours), thereby embrittling the grain boundaries (rare earth-rich phase) of the SC alloy.

[0048] (3) Coarse Crushing Step, First Lubricant Addition Step The SC alloy powder that has undergone the hydrogen cracking step is coarsely crushed (coarse crushing step). At this time, a lubricant may be added to the SC alloy powder (first lubricant addition step). This step may be performed, for example, in an inert atmosphere (nitrogen atmosphere, argon atmosphere, etc.).

[0049] (4) Fine Pulverization Step, Second Lubricant Addition Step The SC alloy powder obtained after the coarse pulverization step is pulverized to a predetermined average particle size D50 (fine pulverization step). The average particle size D50 can be, for example, 2.0 μm-3.5 μm. At this time, a lubricant may be added to the finely pulverized SC alloy powder to improve the flowability of the pulverized powder (second lubricant addition step). This step is preferably performed in an inert atmosphere (such as a nitrogen atmosphere or an argon atmosphere).

[0050] (5) Powder Filling Process, Orientation Process, and Molding Process The SC alloy powder after the pulverization process is filled into a mold. This process is preferably performed, for example, under an inert atmosphere (such as a nitrogen atmosphere or an argon atmosphere). The mold has multiple molding spaces of a predetermined thickness. Each molding space is separated, for example, by multiple partition plates. A magnetic field is applied in a predetermined direction to the mold after powder filling to align the orientation of the SC alloy powder. The SC alloy powder filled into the mold is then compressed to form an SC alloy compact. In this way, an SC alloy compact having a predetermined degree of orientation (e.g., an average orientation of 90% or more) and a predetermined thickness (e.g., a thickness of 1.2 mm to 2.5 mm) can be obtained without a cutting process.

[0051] (6) Mold Breaking Step, First Firing Step The molded body is removed from the mold (mold breaking step). The molded body is sintered at a predetermined sintering temperature (e.g., 900°C-1200°C) for a predetermined time (e.g., 2 hours-5 hours) (first sintering step). This sintering is preferably carried out in a vacuum. Prior to this sintering, heating at a temperature lower than the sintering temperature may be carried out for dehydrogenation.

[0052] (7) Insulating Layer Coating Step The raw material for the insulating layer 13 is coated on the surface of the fired compact. The raw material for the insulating layer 13 can be, for example, a mixture of raw material powder of inorganic crystalline components, compound powder containing a heavy rare earth element, and a solvent. The raw material for the insulating layer 13 may be coated on at least one main surface of the compact, or may be coated on both main surfaces. The main surface of the compact is the surface corresponding to the main surface 11A of the magnet 11. The raw material for the insulating layer 13 may be coated on the entire surface of the compact, i.e., on both main surfaces and side surfaces if the compact is plate-shaped.

[0053] (8) Laminate Temporarily Fixing Process: A predetermined number of molded bodies coated with an insulating layer are stacked and temporarily fixed. Hereinafter, the temporarily fixed stack of molded bodies will also be referred to as a laminate. This method makes it possible to manufacture plate-shaped magnets 11 without the need for a cutting process or other process to cut out plate-shaped magnets from a larger magnet.

[0054] (9) Hot Pressing Step The temporarily fixed laminate is placed in a hot press mold and subjected to uniaxial hot pressing. This step is carried out, for example, under a vacuum atmosphere (for example, 10 －３ Pa-10 －４ The hot pressing may be performed under a pressure of 100 MPa (1 Pa) or in an inert atmosphere (such as a nitrogen atmosphere or an argon atmosphere). The hot pressing temperature may be, for example, 700°C-1100°C. The hot pressing time may be, for example, 1 second to 1 hour. The hot pressing pressure is preferably 3 MPa or more, more preferably 5 MPa or more, and even more preferably 8 MPa or more. There is no particular upper limit to the hot pressing pressure, and it may be, for example, 100 MPa or less. The heat treatment time for the hot pressing may be, for example, 10 minutes to 20 hours. By the above series of steps, a magnet stack 10 comprising magnets 11 and insulating layers 13 is manufactured. The magnet stack 10 is formed by bonding multiple magnets 11 together via the insulating layers 13, forming an integrated structure.

[0055] The hot pressing process allows the heavy rare earth elements (Tb, Dy, etc.) contained in the raw material of the applied insulating layer 13 to diffuse into the magnet 11. The hot pressing process also allows the magnet 11 (e.g., Nd ２ Fe １４ B) flows out to the surface of the magnet 11, and the rare earth element (Nd element) in the magnet 11 flows out to the surface of the magnet 11. ２ A surface layer of a rare earth-rich phase (Nd-rich phase) can be formed near the interface with the insulating layer 13 (a layer containing rare earth elements). Furthermore, by performing the hot pressing process in a nitrogen atmosphere, the surface coating layer 15 can be suitably formed. Furthermore, this hot pressing process can make the insulating layer 13 sufficiently thin and uniform in thickness.

[0056] The magnet stack 10 obtained as described above can be considered to be a magnet stack manufactured by hot pressing (hot uniaxial pressing) a laminate in which the raw material for the insulating layer 13 is sandwiched between at least one pair of magnets 11, 11 (sintered bodies of SC alloy), and applying pressure in a direction that crushes the raw material for the insulating layer 13. The magnet stack 10 can also be considered to be a magnet stack manufactured by arranging a first magnet 11 (sintered body of SC alloy), the raw material for the insulating layer 13, and a second magnet 11 (sintered body of SC alloy) in this order to form a laminate, and then applying pressure to the first magnet 11 and the second magnet 11 from both sides while heating the laminate. The raw material for the insulating layer 13 may further contain a component containing a heavy rare earth element. The raw material for the insulating layer 13 preferably contains inorganic crystals. The raw material for the insulating layer 13 may further contain a component containing a heavy rare earth element. For example, the raw material for the insulating layer 13 may be CaF ２ and TbF ３ When the total of CaF is taken as 100 mass % ２ It is preferable that the content of TbF is 20 mass % to 40 mass %. ３ It is preferable that the content is 60 mass % to 80 mass %.

[0057] 3. Uses of the Magnet Laminate 10 The uses of the magnet laminate 10 are not particularly limited. The magnet laminate 10 is suitable as a magnet for motors. The magnet laminate 10 has low eddy current loss generated internally and excellent magnetic properties, which can contribute to one or more of the following effects: motor miniaturization, suppression of heat generation, improved heat resistance, and improved heat dissipation. Furthermore, when the insulating layer 13 of the magnet laminate 10 is primarily composed of inorganic crystals, its insulating performance is less susceptible to changes due to the effects of humidity, temperature, and deterioration over time than bonding layers made of resin or the like. Therefore, the magnet laminate 10 is useful in a variety of applications where resistance to changes in insulating performance is desired.

[0058] An example of a motor 30 equipped with a magnet laminate 10 will be described below with reference to FIGS. 11 and 12 . The motor 30 includes a stator 31 and a rotor 33 arranged inside the stator 31. The magnet laminate 10 is arranged in the rotor 33, and a winding (not shown) is arranged in the stator 31. The motor 30 in FIG. 11 is an inner rotor type in which the magnets are arranged on the inside (rotating shaft side) and the windings are arranged on the outside. The motor is not limited to the inner rotor type. For example, the motor may be an outer rotor type in which the windings are arranged on the inside (rotating shaft side) and the magnets are arranged on the outside.

[0059] The rotor 33 includes a rotating shaft 34, a rotating core 35, and a plurality of laminated magnets 10. The rotating core 35 is formed by laminating electromagnetic steel sheets. A shaft hole 37 is formed in the center of the rotating core 35. The rotating shaft 34 is inserted into the shaft hole 37. A plurality of magnet holes 39 are formed in the rotating core 35 at intervals in the circumferential direction. A laminated magnet 10 is inserted into each magnet hole 39.

[0060] 4. Actions and Effects of the Present Embodiment The magnet laminate 10 of the present embodiment is capable of reducing eddy current loss generated internally and has excellent magnetic properties. The reasons for this are presumed to be as follows. Note that the present disclosure is not limited to this presumption. It is presumed that the magnetic flux density can be increased because the total rare earth element content of magnet 11 is 31.0 mass% or less. Furthermore, it is presumed that the permittivity of magnet laminate 10 at 1 kHz in the first direction is 1.0 or more and 5.0 or less, so it is presumed that eddy current loss can be reduced while favorably maintaining magnetic flux density.

[0061] Furthermore, in the magnet laminate 10, when the insulating layer 13 is primarily composed of inorganic crystals, eddy current loss is less likely to change. The reason for this is presumed to be as follows. However, the present disclosure is not limited to this presumption. It is presumed that the insulating layer 13 primarily composed of inorganic crystals shows almost no change in resistance from room temperature (e.g., 25°C) to 180°C, making it possible to reduce eddy current loss over a wide temperature range. Furthermore, since the insulating layer 13 primarily composed of inorganic crystals has a thermal expansion coefficient close to that of the magnet 11, it is thought that the insulating layer 13 is less likely to deteriorate even with thermal cycling. For this reason as well, it is presumed that the durability (heat resistance) of the magnet laminate 10 of this embodiment is improved.

[0062] The magnet stack 10 of this embodiment has an insulating layer 13 between the magnets 11, 11. With this configuration, the insulating layer 13, which is primarily composed of inorganic crystals, can bond (adhere) the magnets 11, 11 with sufficient strength. Furthermore, when the insulating layer 13 is primarily composed of inorganic crystals, it can be made thinner while maintaining sufficient bonding strength compared to bonding layers made of resin or the like. Furthermore, unlike this embodiment, if amorphous glass were used for the insulating layer, there is a concern that the magnets would oxidize and their magnetic properties would be impaired. On the other hand, because the insulating layer 13 of this embodiment is primarily composed of inorganic crystals, the magnetic properties of the magnets 11 can be suitably maintained.

[0063] Furthermore, when the insulating layer 13 contains at least one type of fluoride of Group 2A of the periodic table as inorganic crystals, the eddy current loss can be further reduced.

[0064] Furthermore, when a surface coating layer of rare earth nitride is present, moisture resistance can be improved.

[0065] The present disclosure will be explained in more detail below with reference to examples.

[0066] 1. Fabrication of Laminated Magnets The "laminated magnets" are made by stacking multiple "magnets 11," and the number of laminations of "magnets 11" in each example and comparative example is shown as the "number of divisions" in Table 2. The total thickness (dimension in the lamination direction) of each laminated magnet is set to 50 mm. Therefore, each laminated magnet has the number of "magnets 11" stacked per 50 mm of thickness shown in Table 2. In other words, each laminated magnet is divided into the number of magnets shown in Table 2 per 50 mm of thickness. The thickness of the "magnets 11" was adjusted for each example and comparative example so that the number of laminations of "magnets 11" per 50 mm of thickness of the laminated magnet was the number of divisions shown in Table 2. The thickness of the "magnets 11" for each example and comparative example was adjusted based on the thickness of the molding space for the powder filling process described below. The planar shape of each "magnet 11" was rectangular (5 mm x 16 mm).

[0067] <Example 2-21> (1) SC alloy preparation step The main raw materials of a Nd / Pr alloy, an alloy containing Co, Al, Cu, Ga, and Zr, and a metal element were mixed to prepare a strip cast alloy (SC alloy) (for example, composition: Nd ２ Fe １４ B) was prepared under an argon atmosphere. The SC alloy was a plate-shaped powder with a main surface dimension of 10 mm × 10 mm to 20 mm × 20 mm.

[0068] (2) Hydrogen Crushing Step The SC alloy was allowed to absorb hydrogen in a hydrogen furnace (hydrogen atmosphere, 200°C, 2 hours) to embrittle the grain boundaries (neodymium-rich phases) of the SC alloy.

[0069] (3) Coarse grinding step, first lubricant addition step A lubricant was added to the SC alloy powder that had undergone the hydrogen crushing step. Methyl caprylate was used as the lubricant. The lubricant was mixed at a ratio of 0.03% by mass to 0.07% by mass relative to the amount of SC alloy. While adding the lubricant to the SC alloy powder, the powder was coarsely ground using a stirrer in a nitrogen or argon atmosphere. The average particle size of the SC alloy after coarse grinding was 50 μm to 500 μm.

[0070] (4) Fine pulverization step, second lubricant addition step The SC alloy powder after adding the lubricant was finely pulverized using a jet mill under a nitrogen atmosphere. The average particle size D50 after fine pulverization was 2.5 μm-3.5 μm. A lubricant was added to the SC alloy powder after fine pulverization. Methyl laurate was used as the lubricant. The mixing ratio of the lubricant to the amount of SC alloy was 0.05% by mass-0.1% by mass.

[0071] (5) Powder filling step, orientation step, and molding step The SC alloy powder after the pulverization step and the second lubricant addition step was filled into each molding space of a mold provided with multiple partition plates in a nitrogen atmosphere. Each compact formed in each molding space corresponds to each magnet to be stacked in a later step. A magnetic field (e.g., 5000 V) was applied to the mold after powder filling in the planar direction of each compact (direction perpendicular to the thickness direction) to align the orientation of the SC alloy powder. The SC alloy powder filled in the mold was compressed to form an SC alloy compact. The pressure molding conditions were pressure: 5 MPa-20 MPa, packing density: 3.0 g / cm ３ -4.0 g / cm ３ , relative density: 40%-52%.

[0072] (6) Mold Disassembly Process, First Firing Process The outer frame was removed from the mold, and a continuous arrangement of molded bodies and partition plates (the object to be fired) was prepared. For dehydrogenation, the object to be fired (with the partition plates) was heated at 500°C for 3-4 hours in an Ar atmosphere. Thereafter, the object to be fired (with the partition plates) was held at 930°C-1050°C for 3 hours and fired in a vacuum atmosphere.

[0073] (7) Insulating Layer Coating Step After the first firing step, the partition plates were removed from the sintered object, and the raw material for the insulating layer was coated on six surfaces of the magnet before lamination. The raw material for the insulating layer consisted of the compound powder of the main component listed in Table 1 and TbF ３ The compound powder and the solvent were mixed. ３ The ratio of the compound powder was 10 mass % to 20 mass %. The thickness of the insulating layer raw material was 12 μm or more and 14 μm or less. The insulating layer raw material was applied in the air by a spray method.

[0074] (8) Laminate Temporarily Fixing Process The magnets coated with the insulating layer were stacked in air in batches of 10 to 28 sheets, as shown in Table 2. The number of sheets stacked was adjusted so that the dimension of the laminated magnet in the stacking direction was 50 mm. This method makes it possible to manufacture plate-shaped magnets without the need for a cutting process or other process to cut out plate-shaped magnets from a larger magnet.

[0075] (9) Hot Pressing Process The temporarily fixed laminate was placed in a hot press mold and subjected to uniaxial hot pressing. The hot pressing conditions for each example were as shown in Table 1. In Table 1, "air" under "atmosphere" indicates air atmosphere, "vac" indicates vacuum, and "N2" indicates nitrogen atmosphere. The hot pressing pressure time was 1 second to 1 hour, and the hot pressing heat treatment time was 10 minutes to 20 hours. In this way, laminated magnet samples of Examples 1-21 were produced.

[0076] Example 1 and Comparative Examples 1-4 In Example 1 and Comparative Examples 1-4, the insulating layer coating step and pressing step described below were performed instead of the insulating layer coating step (7) and hot pressing step (9) described above. The steps other than the insulating layer coating step and pressing step described below were the same as the steps (1)-(6) and (8) described above for Example 2-21, and samples of each laminated magnet were produced.

[0077] In Example 1 and Comparative Examples 1-4, in the insulating layer coating step, first, TbF ３ A mixture of the compound powder and solvent was applied to the substrate. The substrate was then heat-treated until the coating film on the surface was completely removed. After that, a resin having the main component shown in Table 1 was applied.

[0078] In Example 1 and Comparative Examples 1-4, the temporarily fixed laminate was placed in a press mold and pressed uniaxially in the pressing process. This process was carried out in an air atmosphere. The pressing temperature was 25°C, the pressing time was longer than the time required for the resin to harden, and the pressing pressure was 3 MPa.

[0079] Comparative Example 5: In Comparative Example 5, a single block-shaped magnet was used instead of a laminated magnet. Specifically, in Comparative Example 3, the SC alloy powder after the fine pulverization step and the second lubricant addition step was filled into a molding die that was not provided with multiple partition plates. In Comparative Example 3, a block-shaped magnet was obtained in the same manner as in Examples 1-21, except that (7) the insulating layer application step, (8) the laminate temporary fixing step, and (9) the hot pressing step were not performed.

[0080] 2. Characteristics of Examples and Comparative Examples Table 1 summarizes the characteristics of the magnets and insulating layers of each example and comparative example. The "TRE" column under "Magnet" indicates the total amount of rare earth elements in the magnet, measured using the method described in the embodiment. The "Number of divisions" column indicates the number of layers of "Magnet 11" as described above. The "Main component" column under "Insulating layer" indicates the compound with the largest amount (mass %) contained in the insulating layer. Regarding the components of the insulating layer, inorganic substances were identified using EPMA and XRD, and organic substances were identified using NMR and IR analysis.

[0081] In the "Surface Coating Layer" column, "Yes" is recorded if a surface coating layer of rare earth nitride is present, and "No" is recorded if a surface coating layer of rare earth nitride is not present. The "Dielectric Constant" column shows the dielectric constant of the magnet measured using the method described in the embodiment. The dielectric constant was measured at 25°C using a measuring device (manufactured by Keysight Technologies, device name: Impedance Analyzer, model number: E4990A). The "Average Orientation Degree" column shows the average orientation degree of the magnet measured using the method described in the embodiment.

[0082]

[0083] 3. Performance Evaluation (1) Evaluation Method for Eddy Current Loss (25°C, 1 kHz) The eddy current loss of the example and comparative example was measured at 25°C and 1 kHz. Specifically, each sample of the example and comparative example was sandwiched between the magnetic poles of a C-type core, and the loss at a frequency of 1 kHz and a magnetic flux density of 0.01 T was measured using a wattmeter.

[0084] The evaluation was made as follows: Eddy current loss (25°C, 1 kHz) "A": 90 W / kg or less "B": greater than 90 W / kg and less than 105 W / kg "C": greater than 105 W / kg

[0085] (2) Evaluation method for residual magnetic flux density Br The residual magnetic flux density Br (T) was measured using a pulse BH tracer. The temperature of the magnet stack during measurement was 50°C. The evaluation direction for the measurement was a direction perpendicular to the surface of the topmost magnet of the magnet stack.

[0086] The evaluation was made as follows: "AA": 1.48T or more; "A": 1.46T or more, less than 1.48T; "B": 1.43T or more, less than 1.46T; "C": Less than 1.43T.

[0087] (3) Evaluation Method of Moisture Resistance To evaluate the moisture resistance of the Examples and Comparative Examples, the samples were left standing for 50 hours under conditions of 70°C and 60% humidity. The volume resistivity (Ω cm) of each sample after the test was measured. The volume resistivity was measured at 25°C using a measuring device (manufactured by Keysight Technologies, Inc., device name: Impedance Analyzer, model number: E4990A). The volume resistivity (Ω cm) of the sample before the test was set to 100%, and the reduction rate (%) of the volume resistivity of the sample after the test was calculated. A low reduction rate (%) of the volume resistivity of the sample after the test is one indicator of high moisture resistance.

[0088] The evaluation was made as follows: "A": Reduction rate of volume resistivity 5% or less; "B": Reduction rate of volume resistivity more than 5% and 10% or less; "C": Reduction rate of volume resistivity more than 10%

[0089] 4. Evaluation Results The evaluation results are also shown in Table 1. Example 1-21 satisfies the following requirements (a) to (c). Requirement (a): The laminated magnet is formed by stacking multiple magnets and insulating layers in a first direction. Requirement (b): The magnet contains a rare earth element, and the total amount of rare earth elements in the magnet is 27% by mass or more and 31.0% by mass or less. Requirement (c): The dielectric constant of the laminated magnet at 1 kHz in the first direction is 1.0 or more and 5.0 or less.

[0090] In contrast, Comparative Examples 1 to 5 do not satisfy the following requirements: Comparative Examples 1 and 2 do not satisfy requirement (b); Comparative Examples 3 and 4 do not satisfy requirement (c); and Comparative Example 5 does not satisfy requirements (a) and (c).

[0091] In Example 1-21, the eddy current loss at 1 kHz was evaluated as "A" or "B." In Example 1-21, the residual magnetic flux density was evaluated as either "AA," "A," or "B." In contrast, in Comparative Examples 4 and 5, the eddy current loss at 1 kHz was evaluated as "C." In Comparative Example 1-3, the residual magnetic flux density was evaluated as "C." It was suggested that Example 1-21 could reduce the eddy current loss generated inside and had excellent magnetic properties.

[0092] Furthermore, among Examples 1 to 21, Examples 10 to 21, which further satisfied the following requirement (d), were evaluated as "A" in terms of eddy current loss at 1 kHz. It was suggested that by satisfying requirement (d), eddy current loss can be further reduced. Requirement (d): The inorganic crystal contains a fluoride of Group 2A of the periodic table.

[0093] Furthermore, among Examples 1-21, Example 7-21, which further satisfied the following requirement (e), was evaluated as "AA" or "A" for residual magnetic flux density. Furthermore, Example 7-21 was evaluated as "A" for moisture resistance. It was suggested that by satisfying requirement (e), the magnetic properties were even more excellent. It was also suggested that by satisfying requirement (e), moisture resistance could be further improved. Requirement (e): A surface coating layer of a rare earth nitride is present.

[0094] Furthermore, among Examples 1-21, Examples 16-21, which further satisfied the following requirement (f), were rated "AA" for residual magnetic flux density. It was suggested that satisfying requirement (f) resulted in even more excellent magnetic properties. Requirement (f): The average degree of orientation of the magnet is 97.0% or more.

[0095] 5. Effects of the Example The example was able to reduce the eddy current loss generated inside, and had excellent magnetic properties.

[0096] The present invention is not limited to the above-described embodiments, and various modifications and variations are possible within the scope of the claims of the present invention.

[0097] DESCRIPTION OF SYMBOLS 10...Laminated magnet 11...Magnet 13...Insulating layer 15...Surface coating layer 30...Motor 31...Stator 33...Rotor 34...Rotating shaft 35...Rotating core 37...Shaft hole 39...Magnet hole

Claims

1. A laminated magnet in which multiple magnets and insulating layers are stacked in a first direction, the magnets contain rare earth elements, the total rare earth element content of the magnet is 27% by mass or more and 31.0% by mass or less, and the dielectric constant of the laminated magnet at 1 kHz in the first direction is 1.0 or more and 5.0 or less.

2. The magnet laminate according to claim 1, wherein the insulating layer is composed mainly of inorganic crystals.

3. The laminated magnet according to claim 2, wherein the inorganic crystal contains at least one type of fluoride of Group 2A of the periodic table.

4. A laminated magnet according to any one of claims 1 to 3, which has a surface coating layer of rare earth nitride.

5. The laminated magnet according to claim 4, wherein the average degree of orientation of the magnets is 97.0% or more.

6. A laminated magnet according to any one of claims 1 to 3, wherein the average degree of orientation of the magnets is 97.0% or more.

7. A motor comprising a laminated magnet according to any one of claims 1 to 3.

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