Laminated magnet and motor

Abstract

Provided is a novel laminated magnet capable of reducing eddy current losses that are generated within in a high-temperature environment of 150ºC or the like.　The laminated magnet (10) comprises a plurality of magnets (11) and an insulating layer (13) present between the plurality of magnets (11). The insulating layer (13) contains an inorganic crystal as the main component.

Description

Laminated magnet and motor

[0001] The present disclosure relates to a laminated magnet and a motor. This application is based on and claims the benefit of priority from Japanese Patent Application Nos. 2023-146621 filed on September 11, 2023, 2023-146626 filed on September 11, 2023, 2023-146620 filed on September 11, 2023, and 2023-146617 filed on September 11, 2023, the entire contents of which are incorporated herein by reference.

[0002] Patent Document 1 discloses a laminated magnet having a resistive layer formed on the surface of a magnet body. The resistive layer is formed by oxidizing the surface of the magnet body. Various laminated magnets have also been proposed with the aim of reducing eddy current loss (for example, Patent Documents 2 to 7).

[0003] JP 2017-174962 A JP 2013-219911 A JP 2007-157903 A JP 2003-164083 A JP 2008-147634 A JP 2007-266200 A JP 2020-41022 A

[0004] In recent years, there have been various demands for laminated magnets. For example, there is a demand for laminated magnets that can reduce eddy current loss that occurs inside them in high-temperature environments such as 150°C. The present disclosure has been made in consideration of the above circumstances, and aims to provide a novel laminated magnet that can reduce eddy current loss that occurs inside them in high-temperature environments such as 150°C. The present disclosure can be realized in the following forms.

[0005] A laminated magnet comprising: a plurality of magnets; and insulating layers present between the plurality of magnets, the insulating layers being primarily composed of inorganic crystals.

[0006] According to the present disclosure, it is possible to provide a novel laminated magnet that can reduce eddy current loss that occurs inside in a high-temperature environment.

[0007] 13A and 13B are perspective views schematically showing an example of a rare earth magnet according to the first embodiment. A top view of a rare earth magnet. A cross-sectional view taken along line A-A in FIG. 2. A cross-sectional view of Alternative Example 1 of the rare earth magnet. An enlarged view showing an enlarged portion of FIG. 4. A diagram for explaining a method for measuring the average degree of orientation of a magnet. A perspective view schematically showing Alternative Example 2 of a rare earth magnet. A diagram for explaining a method for measuring the average degree of orientation of the magnet in Alternative Example 2. A diagram schematically showing each part for measuring the average degree of orientation. A cross-sectional view schematically showing a part of a motor. A plan view of a rotor. A perspective view schematically showing an example of a laminated magnet according to the second embodiment. A top view of a laminated magnet. A cross-sectional view taken along line A-A in FIG. 13. A cross-sectional view of Alternative Example 1 of the laminated magnet. A diagram for explaining a method for measuring the average degree of orientation of the magnet. A diagram for explaining a method for measuring the average degree of orientation of the magnet in Alternative Example 2. A diagram schematically showing each part for measuring the average degree of orientation. A cross-sectional view schematically showing a part of a motor. A plan view of a rotor. 39 is a diagram showing a simulation result of sample B and an image of the magnetic flux density distribution. 39 is a diagram showing a simulation result of sample C and an image of the magnetic flux density distribution. 39 is a perspective view schematically showing an example of a laminated magnet according to a third embodiment. 39 is a top view of the laminated magnet. 39 is a cross-sectional view taken along line A-A of FIG. 25. 39 is an enlarged view showing an enlarged region R1 of FIG. 26. 39 is an enlarged view showing an enlarged region R2 of FIG. 26. 39 is a diagram for explaining the angle of the magnet. 39 is a cross-sectional view of another example 1 of the laminated magnet. 39 is an enlarged view showing an enlarged portion of FIG. 30. 39 is a perspective view schematically showing an example of a laminated magnet according to a fourth embodiment. 39 is a top view of the laminated magnet. 39 is a cross-sectional view taken along line A-A of FIG. 39. 39 is an enlarged view showing an enlarged portion of FIG. 39. 39 is a perspective view schematically showing another example 2 of the laminated magnet. 39 is a top view of another example 2 of the laminated magnet. FIG. 43 is a cross-sectional view of the laminated magnet of FIG. 42 cut along an imaginary plane.

[0008] The present disclosure also aims to achieve one or more of the following: to provide a novel laminated magnet that can reduce eddy current loss generated inside and can concentrate magnetic flux; to provide a novel laminated magnet that can reduce eddy current loss generated inside and is resistant to deterioration over time; and to provide a novel laminated magnet that can reduce eddy current loss generated inside and ensure the bonding strength of multiple plate magnets.

[0009] Here, a preferred example of the present disclosure is described. [1] A laminated magnet (10, 110, 210, 310) comprising a plurality of magnets (11, 111, 211, 311) and insulating layers (13, 113, 213, 313) present between the plurality of magnets (11, 111, 211, 311), wherein the insulating layers (13, 113, 213, 313) are primarily composed of inorganic crystals. [2] The magnet stack (110) according to [1], wherein a plurality of the magnets (111) and the insulating layer (113) are stacked in a first direction, the magnets (111) contain a rare earth element and have a curved shape convex in a second direction as viewed from the first direction, and the average orientation degree of each 1 mm wide portion centered on a normal line at a plurality of points on the curved side of the convex side of the outer periphery of the magnet (111) as viewed from the first direction, from one end to the other end, is 90% or more. [3] The magnet stack (210) according to [1], wherein the magnet (211) contains a crystalline phase containing a rare earth element and an iron element, the total rare earth element content of the magnet (211) is 27% by mass or more and 31.0% by mass or less, and the magnet (211) has a surface layer (217) of a rare earth-rich phase (17A) having a higher rare earth element content than the crystalline phase. [4] The magnet laminate (210) according to [3], wherein a plurality of the magnets (211) and the insulating layers are stacked in a first direction, 10 or more magnets (211) are used per 50 mm of the magnet laminate (210) in the first direction, and the volume resistivity of the magnet laminate (210) in the first direction is 100 Ω cm or more and 2000 Ω cm or less. [5] The magnet laminate (210) according to [3] or [4], wherein the inorganic crystal has a periodic table Group 2A fluoride as a main phase and one or more subphases selected from the group consisting of oxides of the rare earth elements and nitrides of the rare earth elements.[6] The laminated magnet (210) according to any one of [3] to [5], wherein three or more of the magnets (211) are used, the magnets (211) are plate magnets (211) having an upper bottom surface (11A1), a lower bottom surface (11A2), and a side surface (11B), and the angle between the lower bottom surface (11A2) of the topmost magnet (2111) located at the top of the plate magnets (211) and the lower bottom surface (11A2) of each intermediate magnet (2112) excluding the topmost magnet (2111) and the bottommost magnet (2113) located at the bottom is 3° or less. [7] The plate magnet (311) containing a rare earth element, which is the magnet (311), and the insulating layer (313) are alternately laminated, and the plate magnet (311) is Nd. ２ Fe １４B is a main phase, the thickness of the plate magnet (311) is 0.5 mm or more and 4.0 mm or less, when a cross section of the laminated magnet (310) is observed on a virtual plane (VP) including an imaginary line (L1) passing through a center of gravity (G1) of the laminated magnet (310) and extending in the stacking direction, where the cross section is cut so that the cross-sectional area of ​​the laminated magnet (310) is smallest, a Nd-rich phase (17A) having a higher Nd content than the main phase and fluoride particles (314) of a metal of Group 2A of the Periodic Table are present in a range from an interface (I) between the plate magnet (311) and the insulating layer (313) to a depth of 10 μm on the plate magnet (311) side, and the fluoride particles (314) occupy an area ratio of 7% or more and 22% or less in a first region (R1) that satisfies the following conditions (1) to (4): Condition (1): The first region (R1) is located on the plate magnet (311) side of the interface (I) between the plate magnet (311) and the insulating layer (313). Condition (2): The first region (R1) is a rectangle that is 10 μm in the stacking direction and 50 μm in a direction perpendicular to the stacking direction. Condition (3): When a line (L2) is drawn that passes through the center of gravity (G2) of the planar figure of the plate magnet (311) that appears in the cross section and extends in the stacking direction, the center (CT1) of the rectangle is located on the line (L2). Condition (4): The rectangle is in contact with the insulating layer (313). [8] The laminated magnet (310) according to [7], wherein the average particle diameter of the fluoride particles (314) is 2.0 μm or more and 8.0 μm or less. [9] The magnet stack (310) according to [7] or [8], wherein a heavy rare earth element is present in the second region (R2) that satisfies the following conditions (5) to (6): Condition (5): The second region is a rectangle that is 10 μm in the stacking direction and 50 μm in a direction perpendicular to the stacking direction. Condition (6): The center of the rectangle is located at the center of gravity of the planar shape of the plate magnet that appears in the cross section.

[10] The magnet stack (310) according to [9], wherein the following relationship is satisfied: 0.70≧β / α≧0.50, where α% by mass is the amount of the heavy rare earth element in the first region (R1), and β% by mass is the amount of the heavy rare earth element in the second region (R2).

[11] The magnet stack (310) according to any one of [7] to

[10] , wherein three or more plate magnets (311) are used, the plate magnets (311) having an upper bottom surface (11A1), a lower bottom surface (11A2), and side surfaces (11B), and the angle formed between the lower bottom surface (11A2) of the topmost magnet (3111) located at the top among the plate magnets (311) and the lower bottom surface (11A2) of any of the intermediate magnets (3112) excluding the topmost magnet (3111) and the bottommost magnet (3113) located at the bottom is 3° or less.

[12] A motor (30) having the magnet stack (210, 310) according to any one of [3] to

[11] .

[0010] <<First Embodiment>> A first embodiment of the present disclosure will be described in detail below. Note that in the first embodiment, 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 "10" and the upper limit "20". In other words, "10-20" has the same meaning as "10 or more and 20 or less". Furthermore, 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 direction in which the multiple magnets 11 are arranged. One direction perpendicular to the Z-axis direction is the X-axis direction (also referred to as the horizontal direction), and the direction perpendicular to the Z-axis direction and the X-axis direction is the Y-axis direction (also referred to as the vertical direction).

[0011] 1. Rare Earth Magnet 10 (Laminated Magnet) As illustrated in Figures 1 to 3, rare earth magnet 10 comprises a plurality of magnets 11 and insulating layers 13 present between the plurality of magnets 11. Insulating layers 13 are primarily composed of inorganic crystals.

[0012] (1) Magnet 11 (1.1) Composition of 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.

[0013] 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 preferably 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 may be, for example, 27 mass% or more, 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.

[0014] 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.

[0015] 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.

[0016] 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 %.

[0017] 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.

[0018] 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 FIG. 5, 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.

[0019] 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.

[0020] (1.2) Average Orientation of Magnets 11 The average orientation of magnets 11 is preferably 90% or more, and more preferably 95% or more. The higher the average orientation of magnets 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.

[0021] 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 6, 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 6, 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 6 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.

[0022] When the magnet 11 has a convex curved shape, as shown in Figures 7 and 8, 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 curve C1 on the convex side of 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.

[0023] Below, a method for calculating the average degree of orientation when the magnet 11 has a convex curved shape will be described in detail with reference to Figures 8 and 9. The curve on the convex side of the periphery of the magnet 11 as viewed from the Z-axis direction 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 8, multiple points Pn are identified. In this embodiment, five points P1-P5 are identified. On the magnet 11, points P1 and P5 at both ends of the convex curve C1 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 the curve C1, starting from one end. In this embodiment, point P3 is located in the middle of curve C1.

[0024] On the curve C1, the normal line N1-N5 at each point P1-P5 is 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. 9. In reality, the top and bottom surfaces of FIG. 9 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.

[0025] 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.

[0026] (1.3) Shape of Magnet 11 The shape of the magnet 11 is not particularly limited. For example, it is preferable that the magnet 11 be plate-shaped. Plate-shaped magnets 11 have a shorter distance from the surface to the deepest part compared to 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 rare earth magnet 10 in FIG. 1 is stacked with multiple magnets 11 stacked in the thickness direction of the plate-shaped magnets 11. In this laminated magnet, the magnets 11 and insulating layers 13 are stacked alternately. 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 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. 8), as shown in Figures 7 and 8.

[0027] (1.4) Thickness of Magnet 11 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 the thickness of magnet 11 is 0.5 mm or more, it is easy to form magnet 11 while ensuring an average degree of orientation. If the thickness of magnet 11 is 4.0 mm or less, it is easy to diffuse the heavy rare earth element to the interior. Furthermore, if the thickness is 4.0 mm or less, eddy current loss inside rare earth magnet 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 be 0.5 mm or more and 4.0 mm or less in thickness, 4 mm or more and 10 mm or less in length, and 10 mm or more and 30 mm or less in width.

[0028] (2) Insulating Layer 13 (2.1) Composition of Insulating Layer 13 The insulating layer 13 is mainly composed of inorganic crystals. The inorganic crystals are preferably non-magnetic crystalline particles. "Mainly composed 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. The presence of inorganic crystals is determined by X-ray microanalysis or XRD analysis, and the content of inorganic crystals is calculated in combination with composition analysis by EPMA (Electron Probe Micro Analyser).

[0029] 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:

[0030] 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 %.

[0031] 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 rare earth magnet 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.

[0032] (2.2) Presence and Arrangement of Insulating Layer 13 It is sufficient that insulating layer 13 is present at least between magnets 11, 11. The arrangement of insulating layer 13 is, for example, as follows: Insulating layer 13 may be arranged so as to cover the entire surface of magnet 11 (see FIG. 4). In the example of FIG. 4, both upper and lower main surfaces 11A and both side surfaces 11B of each magnet 11 are covered with insulating layer 13, and insulating layer 13 is arranged so as to cover the entire surface of magnet 11. In the example of FIG. 3, the side surfaces 11B of each magnet 11 are not covered with insulating layer 13, and insulating layer 13 is arranged so as to cover only a portion of the surface of magnet 11. 3, the magnet 11 in the top row has one main surface 11A (lower side) covered with an insulating layer 13, but the other main surface 11A (upper side) is not covered with an insulating layer 13, and the insulating layer 13 is arranged in a manner that covers a portion of the surface of the magnet 11. Similarly, in the example of FIG. 3, the magnet 11 in the bottom row has one main surface 11A (upper side) covered with an insulating layer 13, but the other main surface 11A (lower side) is not covered with an insulating layer 13, and the insulating layer 13 is arranged in a manner that covers a portion of the surface of the magnet 11. Furthermore, the insulating layer 13 may be arranged between the multiple magnets 11 in a manner that extends from one side surface 11B (e.g., the left surface in FIG. 33) to the other side surface 11B (e.g., the right surface in FIG. 33) of the magnet 11 (see FIG. 33), or may be arranged in a manner that partially separates the magnets 11. In other words, as long as the rare earth magnet 10 has portions where the magnets 11 are insulated from each other by the insulating layer 13, the magnets 11 may have portions where they are partially connected to each other.

[0033] 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 aligned (the Z-axis direction) where components derived from the insulating layer 13 and components derived from the magnet 11 are mixed. Such a rare earth magnet 10 can be suitably formed by hot pressing. The conditions for hot pressing will be explained later.

[0034] 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. 10 , when the rare earth magnet 10 is used as a motor magnet, etc., the insulating layers 13 are preferably provided along the orientation direction of the magnets 11 (the X-axis direction in FIG. 10 ) 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 rare earth magnet 10 (the X-axis direction in FIG. 10 ), thereby effectively reducing eddy current loss.

[0035] (2.3) Thickness of Insulating Layer 13 The thickness T of insulating layer 13 is not particularly limited. From the viewpoint of ensuring sufficient insulation, the thickness T of 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 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 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 insulating layer 13 is measured, for example, by observing the cross section of rare earth magnet 10 with a scanning electron microscope (SEM) and measuring the distance between magnets 11 located on both sides of insulating layer 13 (see FIG. 5 ).

[0036] 2. Manufacturing Method of Rare Earth Magnet 10 There are no particular limitations on the manufacturing method of rare earth magnet 10. An example of a manufacturing method for rare earth magnet 10, which is a laminated magnet in which magnets 11 and insulating layers 13 are alternately stacked, is shown below.

[0037] (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.

[0038] (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.

[0039] (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.).

[0040] (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).

[0041] (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.

[0042] (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.

[0043] (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.

[0044] (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.

[0045] (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 －４The hot pressing may be performed under a pressure of 1000 psi (1000 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 hot pressing heat treatment time may be, for example, 10 minutes to 20 hours. Through the above series of steps, a rare earth magnet 10 comprising magnets 11 and insulating layers 13 is produced. The rare earth magnet 10 is formed by bonding multiple magnets 11 together with insulating layers 13, forming an integrated magnet.

[0046] 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. Furthermore, this hot pressing process can make the insulating layer 13 sufficiently thin and uniform in thickness.

[0047] The rare earth magnet 10 obtained as described above can be considered to be a rare earth magnet manufactured by hot pressing (hot uniaxial pressing) a laminate consisting of at least a pair of magnets 11, 11 (sintered SC alloys) sandwiching the raw material for the insulating layer 13, so that pressure is applied in a direction that crushes the raw material for the insulating layer 13. Alternatively, the rare earth magnet 10 can be considered to be a rare earth magnet manufactured by arranging a first magnet 11 (sintered SC alloy), the raw material for the insulating layer 13, and a second magnet 11 (sintered 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 preferably contains inorganic crystals. The raw material for the insulating layer 13 may also 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 %.

[0048] 3. Uses of Rare Earth Magnet 10 There are no particular limitations on the uses of rare earth magnet 10. Rare earth magnet 10 is suitable as a magnet for motors. Rare earth magnet 10 has low eddy current loss generated internally, and eddy current loss is resistant to change, which can contribute to one or more of the following effects: motor miniaturization, heat suppression, improved heat resistance, and improved heat dissipation. Furthermore, the insulating layer 13 of rare earth magnet 10 is less susceptible to changes in insulating performance due to the influence of humidity, temperature, and deterioration over time than insulating layers made of resin or the like. Therefore, rare earth magnet 10 is useful in a variety of applications where resistance to change in insulating performance is desired.

[0049] An example of a motor 30 equipped with a rare earth magnet 10 will be described below with reference to FIGS. 10 and 11 . The motor 30 includes a stator 31 and a rotor 33 arranged inside the stator 31. A rare earth magnet 10 is arranged in the rotor 33, and a winding (not shown) is arranged in the stator 31. The motor 30 in FIG. 10 is an inner rotor type in which the magnet is arranged on the inside (rotating shaft side) and the winding is 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 winding is arranged on the inside (rotating shaft side) and the magnet is arranged on the outside.

[0050] The rotor 33 includes a rotating shaft 34, a rotating core 35, and a plurality of rare earth 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 rare earth magnet 10 is inserted into each magnet hole 39.

[0051] 4. Actions and Effects of the Present Embodiment Because the insulating layer 13 of the rare earth magnet 10 of this embodiment is primarily composed of inorganic crystals, eddy current loss is unlikely to change in high-temperature environments. The reason for this is presumed to be as follows. However, the present disclosure is not limited to this presumption. Since the insulating layer 13, whose primary component is inorganic crystals, shows almost no change in resistance in the range from room temperature (e.g., 25°C) to 150°C, it is presumed that eddy current loss reduction can be achieved over a wide temperature range. Furthermore, since the insulating layer 13, whose primary component is inorganic crystals, has a thermal expansion coefficient close to that of the magnet 11, it is believed that the insulating layer 13 is unlikely to change in quality even through thermal cycling. Note that the difference in thermal expansion coefficient between the insulating layer 13 and the magnet 11 is ±3.0 x 10 －５ / K or less. It is presumed that this is also the reason why the durability (heat resistance) of the rare earth magnet 10 of this embodiment is improved.

[0052] The rare earth magnet 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, allows the magnets 11, 11 to be bonded (adhered) with sufficient strength. Furthermore, because 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 magnet would oxidize and its 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 magnet 11 can be suitably maintained. [Example]

[0053] The present disclosure will be explained in more detail below with reference to examples.

[0054] 1. Fabrication of Laminated Magnets as Rare Earth Magnets In Experimental Examples 1A to 16A and Experimental Examples 1B to 4B, "laminated magnets" corresponding to "rare earth magnet 10" were fabricated.

[0055] <Experimental Examples 1A to 16A> (1) SC Alloy Preparation Step The main raw materials of an 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.

[0056] (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.

[0057] (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.

[0058] (4) Fine pulverization step, second lubricant addition step The SC alloy powder after adding the lubricant was finely pulverized in a nitrogen atmosphere using a jet mill. The average particle size D50 after fine pulverization was 2.0 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.

[0059] (5) Powder Filling Step, Orientation Step, and Compaction 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 subsequent step. In the samples of Experimental Examples 1A to 16A and Experimental Examples 1B to 4B, each magnet was a rectangular parallelepiped with a thickness of 2 mm, 5 mm, and 16 mm. 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 to 20 MPa, packing density: 3.0 g / cm. ３ -4.0 g / cm ３ , relative density: 40%-52%.

[0060] (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.

[0061] (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. ３The 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.

[0062] (8) Laminate Temporarily Fixing Process 25 magnets coated with an insulating layer were stacked in air and temporarily fixed. The number of magnets stacked was adjusted so that the dimension of the laminated magnet in the stacking direction was 50 mm. This method allows for the production of plate-shaped magnets without the need for a cutting process or other process to cut out plate-shaped magnets from a larger magnet.

[0063] (9) Hot Pressing Step The temporarily fixed laminate was placed in a hot press mold and subjected to uniaxial hot pressing. This step was carried out under a vacuum atmosphere (for example, 10 －３ Pa-10 －４ The hot pressing was carried out in a vacuum atmosphere (700-1100°C), or in an inert atmosphere (nitrogen atmosphere, argon atmosphere). The hot pressing temperature was 700-1100°C, the hot pressing time was 1 second to 1 hour, the hot pressing pressure was 3 MPa or more and 100 MPa or less, and the hot pressing heat treatment time was 10 minutes to 20 hours. In this manner, laminated magnet samples for Experimental Examples 1A to 16A were produced.

[0064] <Experimental Examples 1B to 4B> In Experimental Examples 1B to 4B, 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) to (6) and (8) described above for Experimental Examples 1A to 16A, and laminated magnet samples for Experimental Examples 1B to 4B were produced.

[0065] In Experimental Examples 1B to 4B, 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.

[0066] In Experimental Examples 1B to 4B, the temporarily fixed laminate was placed in a press mold and pressed uniaxially. This step was carried out in an air atmosphere. The press temperature was 25°C, the press time was at least the time required for the resin to harden, and the press pressure was 3 MPa.

[0067] 2. Characteristics of Experimental Examples 1A to 16A and Experimental Examples 1B to 4B Table 1 summarizes the characteristics of the magnets and insulating layers of Experimental Examples 1A to 16A and Experimental Examples 1B to 4B. The "Type" column of "Magnet" indicates the type of magnet. "Neodymium magnet" means Nd ２ Fe １４ This indicates that the magnet has B as its main phase. The "Main Component" column under "Insulating Layer" indicates the compound with the highest 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. The "Main Component Content" column indicates the mass % of the main component when the entire insulating layer is taken as 100 mass %. In Experimental Examples 1A to 16A, the main component exists as inorganic crystals, and the "Main Component Content" is the amount of inorganic crystals contained in the insulating layer. The amount of inorganic crystals (mass %) was determined by X-ray microanalysis or XRD analysis, and calculated in combination with EPMA composition analysis. Note that in Experimental Examples 1B to 4B, components other than inorganic crystals in the insulating layer are considered to be the main components, and the value listed is the amount of inorganic crystals (mass %) minus 100 (mass %). The "Thickness" column under "Insulating Layer" indicates the thickness of the insulating layer. The thickness of the insulating layer was measured by observing the cross section of the laminated magnet with a SEM (scanning electron microscope).

[0068]

[0069] 3. Performance Evaluation (1) Evaluation Method for Eddy Current Loss (25°C, 1 kHz) The eddy current loss was measured for Experimental Examples 1A to 16A and Experimental Examples 1B to 4B at 25°C and 1 kHz. Specifically, each sample of Experimental Examples 1A to 16A and Experimental Examples 1B to 4B 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.

[0070] 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

[0071] (2) Thermal Cycle Test The following thermal cycle test was conducted to evaluate the heat resistance of Experimental Examples 1A to 16A and Experimental Examples 1B to 4B. The thermal cycle consisted of a low temperature of 25°C and a high temperature of 180°C (1 minute) per cycle, and the number of thermal cycles was 1,000. The bending strength (MPa) of each sample after the test was measured in accordance with JIS R1664:2004. The bending strength (MPa) of the sample before the test was set to 100%, and the reduction rate (%) of the bending strength of the sample after the test was calculated. A low reduction rate (%) of the bending strength of the sample after the test is one indicator of high durability (heat resistance).

[0072] The evaluation was made as follows: "A": The rate of decrease in bending strength was 5% or less; "B": The rate of decrease in bending strength was more than 5% and less than 12%; "C": The rate of decrease in bending strength was more than 12%.

[0073] (3) Method for Evaluating Eddy Current Loss (150°C, 1 kHz) The eddy current losses of Experimental Examples 1A to 16A and Experimental Examples 1B to 4B were measured at 150°C and 1 kHz under the same conditions as those for the eddy current loss (25°C, 1 kHz) described above, except for the temperature. The eddy current loss at 25°C and 1 kHz was set as 100%, and the rate of change (%) of the eddy current loss at 150°C and 1 kHz was calculated.

[0074] The evaluation was made as follows: "A": rate of change in eddy current loss is 5% or less; "B": rate of change in eddy current loss is more than 5% and less than 10%; "C": rate of change in eddy current loss is more than 10%

[0075] 4. Evaluation Results The evaluation results are shown in Table 1. Experimental Examples 1A to 16A satisfy the following requirement (a). In contrast, Experimental Examples 1B to 4B do not satisfy the following requirement (a). Requirement (a): The insulating layer contains inorganic crystals as its main component.

[0076] Experimental Examples 1A to 16A were evaluated as "A" or "B" for eddy current loss at 25°C and 1 kHz. Experimental Examples 1A to 16A were evaluated as "A" or "B" for the thermal cycle test. Experimental Examples 1A to 16A were evaluated as "A" or "B" for eddy current loss at 150°C and 1 kHz. In contrast, Experimental Examples 1B to 4B were evaluated as "C" for eddy current loss at 150°C and 1 kHz. It was suggested that Experimental Examples 1A to 16A can reduce eddy current loss generated internally in a high-temperature environment.

[0077] Furthermore, among Experimental Examples 1A to 16A, Experimental Examples 1A to 3A, which further satisfied the following requirement (b), were all rated "A" in the evaluation of eddy current loss (25°C, 1 kHz), the evaluation of thermal cycle test, and the evaluation of eddy current loss (150°C, 1 kHz). It was suggested that by satisfying requirement (b), eddy current loss can be further reduced and eddy current loss is less likely to change. Requirement (b): Contains a fluoride of Group 2A of the periodic table as the inorganic crystal.

[0078] 5. Effects of the Examples Experimental Examples 1A to 16A were able to reduce eddy current loss generated inside in a high temperature environment such as 150°C.

[0079] 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.

[0080] <<Second Embodiment>> A second embodiment of the present disclosure will be described in detail below. In this specification, when a numerical range is indicated using "-", it is assumed that the range includes both the lower and upper limits, unless otherwise specified. For example, the expression "10-20" includes both the lower limit "10" and the upper limit "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 limits 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 110. One direction perpendicular to the Z-axis direction is 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 the Y-axis direction.

[0081] 1. Magnet Stack 110 As illustrated in Figures 12 to 14, the magnet stack 110 is formed by stacking multiple magnets 111 and insulating layers 113 in a first direction. The magnets 111 contain a rare earth element. When viewed from the first direction, the magnets 111 have a curved shape that is convex in a second direction, and the average orientation of each 1 mm wide portion centered on the normal line at multiple points on the curve on the convex side in the second direction from one end to the other on the outer periphery of the magnet 111 when viewed from the first direction is 90% or higher. The insulating layers 113 are primarily composed of inorganic crystals.

[0082] (1) Magnet 111 The composition of the magnet 111 is the same as that explained in the section "(1.1) Composition of the magnet 11" in the first embodiment, and the description in this section applies as is.

[0083] The average degree of orientation of the magnets 111 and a method for measuring it will be described later. In Figures 13 and 14, the outline arrows indicate the orientation direction. Multiple magnets 111 can be used, for example, lined up in a direction perpendicular to the orientation direction, as shown in Figure 14.

[0084] The shape of the magnet 111 is not particularly limited. The magnet 111 is preferably, for example, plate-shaped. The plate-shaped magnet 111 has a shorter distance from the surface to the deepest part compared to a thicker block-shaped magnet. Therefore, the plate-shaped magnet 111 is suitable because it facilitates the diffusion of heavy rare earth elements into the interior when the heavy rare earth elements are diffused through grain boundaries. Plate-shaped magnets 111 can be suitably used as a laminated magnet in which multiple magnets 111 and insulating layers 113 are stacked. The laminated magnet 110 of FIG. 12 includes multiple magnets 111 stacked with the thickness direction of the plate-shaped magnet 111 as the stacking direction. In this laminated magnet 110, the magnets 111 and insulating layers 113 are alternately stacked. In a laminated magnet, each magnet 111 is sometimes referred to as a magnet body. The shape of the magnet 111 viewed from the first direction (Z-axis direction) will be described later.

[0085] The thickness of the magnet 111 is the same as that explained in the section "(1.4) Thickness of the magnet 11" in the first embodiment, and the description in this section applies as is.

[0086] (2) Insulating Layer 113 The composition of the insulating layer 113 is the same as that explained in the section "(2.1) Composition of Insulating Layer 113" in the first embodiment, and the description in this section applies as is.

[0087] The insulating layer 113 only needs to be present between the magnets 111, 111. The insulating layer 113 may be arranged, for example, as follows: The insulating layer 113 may be arranged so as to cover the entire surface of the magnet 111 (see FIG. 15). In the example of FIG. 15, both the upper and lower main surfaces 11A and both side surfaces 11B of each magnet 111 are covered with the insulating layer 113, and the insulating layer 113 is arranged so as to cover the entire surface of the magnet 111. The insulating layer 113 may be arranged so as to cover only a portion of the surface of the magnet 111 (see FIG. 14). In the example of FIG. 14, the side surfaces 11B of each magnet 111 are not covered with the insulating layer 113, and the insulating layer 113 is arranged so as to cover only a portion of the surface of the magnet 111. 14, the topmost magnet 111 has one (lower) main surface 11A covered with insulating layer 113, but the other (upper) main surface 11A is not covered with insulating layer 113, with insulating layer 113 arranged to cover part of the surface of magnet 111. Similarly, in the example of Fig. 14, the bottommost magnet 111 has one (upper) main surface 11A covered with insulating layer 113, but the other (lower) main surface 11A is not covered with insulating layer 113, with insulating layer 113 arranged to cover part of the surface of magnet 111.

[0088] The insulating layer 113 is preferably provided so as to be in direct contact with the magnet 111. The insulating layer 113 may also be an insulating bonding layer that bonds (adheses) the magnets 111, 111 located on both sides. From the viewpoint of bonding the magnets 111, 111 with sufficient strength, the insulating layer 113 preferably has a region in the direction in which the multiple magnets 111 are arranged (the Z-axis direction) where components derived from the insulating layer 113 and components derived from the magnet 111 are mixed. Such a magnet stack 110 can be suitably formed by hot pressing. The conditions for hot pressing will be described later.

[0089] The insulating layers 113 may be provided along the orientation direction of the magnetic field of each magnet 111 (e.g., the X-axis direction in FIG. 14 , the direction of the white arrow in FIG. 14 ), or along a direction intersecting the orientation direction (e.g., the X-axis direction in FIG. 14 ) (e.g., the Z-axis direction in FIG. 14 ). Note that, as shown in FIG. 19 , when the magnet stack 110 is used as a motor magnet or the like, the insulating layers 113 are preferably provided along the orientation direction of the magnets 111 (the X-axis direction in FIG. 19 ) from the perspective of efficiently reducing eddy current loss. With this configuration, the insulating layers 113 are arranged approximately parallel to the direction in which the magnetic flux generated in the stator 131 passes through the magnet stack 110 (the X-axis direction in FIG. 19 ), thereby effectively reducing eddy current loss.

[0090] The thickness of the insulating layer 113 is the same as that explained in the section "(2.3) Thickness of the insulating layer 113" in the first embodiment, and the description in this section applies as is.

[0091] (3) Configuration of the magnet stack 110 From the viewpoint of reducing eddy current loss, it is preferable that 10 or more magnets 111 are used per 50 mm of the dimension of the magnet stack 110 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.

[0092] (4) Shape of magnet 111 as viewed from the first direction When viewed from the first direction, magnet 111 has a curved shape that is convex in the second direction. In this embodiment, the first direction corresponds to the Z-axis direction. The second direction corresponds to the X-axis direction.

[0093] The shape of magnet 111 is not particularly limited as long as it is a curved shape that is convex in the second direction. Magnet 111 is preferably arc-shaped from the viewpoint of concentrating magnetic flux. In this disclosure, an arc-shaped shape is defined as a shape in which, on the periphery of the magnet as viewed from the first direction, a curve C1 on the convex side is generally arc-shaped, and a line opposing curve C1 (an opposing line C2, described below) is also generally arc-shaped. In other words, the arc-shaped shape includes two generally arc-shaped curves that extend parallel to each other on the contour line of the periphery of the magnet as viewed from the first direction. Magnet 111 may also have a convex curved shape other than an arc-shaped shape.

[0094] The magnet 111 in Figures 16 and 17 will be specifically described below, with the curve C1 representing the convex curve on the periphery of the magnet 111 as viewed from the Z-axis direction, and the opposing line C2 representing the line that traces the edge opposite to the curve C1. The magnet 111 in Figure 16 is an arc-shaped magnet. The curve C1 is a perfect circular arc. The radius of curvature of the curve C1 is constant. The opposing line C2 is a perfect circular arc that is concentric with the curve C1. In Figure 16, the center of curvature of the curve C1 and the opposing line C2 is indicated by point O. The opposing line C2 is a curve (a parallel curve to the curve C1) that is a constant distance from each point on the curve C1 in the normal direction. The magnet 111 in Figure 17 is an example of a convex curved shape other than an arc shape. This magnet 111 is approximately U-shaped. The curve C1 is a curve with a variable radius of curvature. Specifically, the curve C1 has a straight portion and a portion that is bent from the straight portion. When the radius of curvature of the curve C1 changes, it is preferable that the radius of curvature change continuously. The opposing line C2 is a curve (a parallel curve to the curve C1) that is located at a certain distance from each point on the curve C1 in the normal direction.

[0095] The radius of curvature of the curve C1 is not particularly limited. Hereinafter, the smallest radius of curvature among the radii of curvature of points on the curve C1 is referred to as the minimum radius of curvature. When the curve C1 is an arc of a perfect circle, the minimum radius of curvature is the same as the radius of the perfect circle. The minimum radius of curvature of the curve C1 is preferably 10 mm or more, more preferably 20 mm or more, and even more preferably 30 mm or more. From the viewpoint of favorably concentrating the magnetic flux density, the minimum radius of curvature of the curve C1 is preferably 100 mm or less, more preferably 75 mm or less, and even more preferably 50 mm or less. From these viewpoints, the minimum radius of curvature of the curve C1 is preferably 10 mm or more and 100 mm or less, more preferably 20 mm or more and 75 mm or less, and even more preferably 30 mm or more and 50 mm or less. When the curve C1 is an arc of a perfect circle, the central angle of the curve C1 is preferably 120° or more and 180° or less, more preferably 150° or less.

[0096] (5) Average Orientation of Magnet 111 Magnet 111 has an average orientation of 90% or more in each 1 mm wide portion 112 centered on a normal Nn at multiple points Pn from one end to the other end of curve C1 on the convex side in the second direction on the outer periphery of magnet 111 when viewed from the first direction. The average orientation can be, for example, 92% or more, 94% or more, 95% or more, or 96% or more. The higher the average orientation of magnet 111, the better, but it is usually 99.5% or less.

[0097] The method for measuring the average degree of orientation of magnet 111 will be described below with reference to Figures 16 and 18. The average degree of orientation of magnet 111 is determined 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 end of the convex curve C1 on the outer periphery of magnet 111 as viewed from the first direction (Z-axis direction). The number of multiple points Pn is not particularly limited. If the size of magnet 111 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.

[0098] First, as shown in FIG. 16, multiple points Pn are identified. In this embodiment, five points P1-P5 are identified. On the magnet 111, points P1 and P5 are taken at both ends of the curve C1 on the convex side, 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 taken in order from one end at positions that divide the distance between points P1 and P5 at both ends of the curve C1 into equal intervals (positions that divide the distance into four equal parts in this embodiment). Note that point P3 in this embodiment is located in the middle of the curve C1.

[0099] On the curve C1, the normal lines N1-N5 at each point P1-P5 are identified. A 1 mm wide portion 112 is cut out from the magnet 111, centered on the normal line Nn. Each portion 112 is, for example, approximately rectangular prism-shaped, as shown in FIG. 18. In reality, the top and bottom surfaces of FIG. 18 are curved. The degree of orientation of each portion 112 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 112 is calculated as the average degree of orientation. The average degree of orientation can also be calculated for the magnet 111 of FIG. 17 using the same measurement method as above.

[0100] In addition, the magnet 111 can achieve the above average orientation degree of 90% or more by applying a magnetic field that spreads in the normal direction of the curve C1 of the magnet 111 in the orientation process described below, for example.

[0101] 2. Manufacturing Method of the Magnet Laminate 110 There are no particular limitations on the manufacturing method of the magnet laminate 110. An example of a manufacturing method of the magnet laminate 110 in which magnets 111 and insulating layers 113 are alternately stacked is shown below.

[0102] In the manufacturing method of the laminated magnet 110, the (1) SC alloy preparation step, (2) hydrogen crushing step, (3) coarse pulverization step, first lubricant addition step, (4) fine pulverization step, and second lubricant addition step are the same as the explanations of the (1) SC alloy preparation step, (2) hydrogen crushing step, (3) coarse pulverization step, first lubricant addition step, (4) fine pulverization step, and second lubricant addition step in "2. Manufacturing method of rare earth magnet 10" in the first embodiment, and this explanation applies as is.

[0103] (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). A mold having multiple molding spaces of a predetermined thickness is used. 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. For example, if the magnet 111 has an arc shape as shown in FIG. 16, a radial magnetic field (a magnetic field in which magnetic field lines radiate) is applied. 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. The shape of the compact can be made as desired by changing the shape of the mold into which the SC alloy powder is filled after the pulverization process. In addition, the average degree of orientation of the compact can be increased by using an orientation coil that matches the shape of the compact.

[0104] In the manufacturing method of the magnet laminate 110, the (6) mold disassembly step, the first firing step, the (7) insulating layer application step, the (8) laminate temporary fixing step, and the (9) hot pressing step are the same as the explanations of the (6) mold disassembly step, the first firing step, the (7) insulating layer application step, the (8) laminate temporary fixing step, and the (9) hot pressing step in “2. Manufacturing method of rare earth magnet 10” in the first embodiment, and this explanation applies as is.

[0105] The magnet stack 110 obtained as described above can be understood as a magnet stack manufactured by hot pressing (hot uniaxial pressing) a laminate in which the raw material of the insulating layer 113 is sandwiched between at least a pair of magnets 111, 111 (sintered bodies of SC alloy), so that pressure is applied in a direction that crushes the raw material of the insulating layer 113. The magnet stack 110 can also be understood as a magnet stack manufactured by arranging a first magnet 111 (sintered body of SC alloy), the raw material of the insulating layer 113, and a second magnet 111 (sintered body of SC alloy) in this order to form a laminate, and applying pressure to the first magnet 111 and the second magnet 111 from both sides while heating the laminate. The raw material of the insulating layer 113 may further contain a component containing a heavy rare earth element. For example, the raw material of the insulating layer 113 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 %.

[0106] 3. Uses of the Magnet Laminate 110 The uses of the magnet laminate 110 are not particularly limited. The magnet laminate 110 is suitable as a magnet for motors. The magnet laminate 110 has low eddy current loss generated internally and can concentrate magnetic flux, which can contribute to one or more of the following effects: motor miniaturization, heat suppression, improved heat resistance, and improved heat dissipation. Furthermore, because the insulating layer 113 of the magnet laminate 110 is primarily composed of inorganic crystals, its insulating performance is less susceptible to changes due to humidity, temperature, and deterioration over time than insulating layers made of resin or the like. Therefore, the magnet laminate 110 is useful for a variety of applications where resistance to changes in insulating performance is desired.

[0107] An example of a motor 130 including a magnet stack 110 will be described below with reference to FIGS. 19 and 20 . The motor 130 includes a stator 131 and a rotor 133 arranged inside the stator 131. The magnet stack 110 is arranged in the rotor 133, and a winding (not shown) is arranged in the stator 131. The motor 130 in FIG. 19 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.

[0108] The rotor 133 includes a rotating shaft 134, a rotating core 135, and a plurality of laminated magnets 110. The rotating core 135 is formed by laminating electromagnetic steel sheets. A shaft hole 137 is formed in the center of the rotating core 135. The rotating shaft 134 is inserted into the shaft hole 137. A plurality of magnet holes 139 are formed in the rotating core 135 at intervals in the circumferential direction. A laminated magnet 110 is inserted into each magnet hole 139. Each laminated magnet 110 is arranged with the convex side of its convex curved shape facing the rotating shaft 134. Note that the arrangement of the laminated magnets 110 is not limited to the arrangement shown in FIG. 20. For example, two magnets may be arranged side by side in an arc, as in the rotor of sample C shown in the lower part of FIG. 23.

[0109] 4. Functions and Effects of the Present Embodiment The magnet laminate 110 of the present embodiment is composed of multiple magnets 111 and insulating layers 113 stacked together, thereby reducing eddy current loss. However, when magnets 111 with a convex curved shape, as in the present embodiment, are used in the magnet laminate 110, it is difficult to increase the average orientation measured as described above. For example, high-pressure magnetic field pressing is generally considered to be an effective method for increasing the orientation of magnets. However, high-pressure magnetic field pressing is limited to the manufacture of large block magnets due to limitations on the size and shape of the molding die. Therefore, high-pressure magnetic field pressing is unsuitable for manufacturing thin magnets such as those used in magnet laminates. Another method that has been considered is to produce a magnet with a convex curved shape by, for example, parallel-orienting a rectangular magnet when viewed from a first direction and then bending it so that it is convex in a second direction. However, bending a magnet can reduce the orientation of the magnet, making it difficult to ensure a sufficient average orientation. The inventors of the present application have conducted extensive research to improve the average degree of orientation of the magnets 111, and have developed the novel laminated magnet 110 of the present disclosure.

[0110] Since the laminated magnet 110 has an average degree of orientation of 90% or more, it is able to concentrate magnetic flux. Below, a computer simulation is used to examine the magnetic flux distribution of Sample A, Sample B, and Sample C when the magnets are applied to rotors. The finite element method electromagnetic field analysis software JMAG (manufactured by JSOL Corporation) was used to examine the magnetic flux distribution. The upper graphs of Figures 21 to 23 show the relationship between the angle in the range of a central angle of 90° in the rotor and the magnetic flux density. The magnets described below are used for each rotor. The horizontal axis represents the angle (°) with respect to the line OX shown in the rotor in the lower graph. The vertical axis represents the magnetic flux density (W / m ２ 21 to 23 show the rotor and the simulated distribution of magnetic flux density (absolute value). The arrows on each magnet roughly indicate the orientation direction of the magnet.

[0111] The magnets of Samples A, B, and C have the following properties: <Sample A> Shape of magnet when viewed from a first direction: rectangular Area of ​​main surface of magnet: 96.8 mm２ (Long side dimension: 22 mm, short side dimension: 4.4 mm) Magnet orientation: Parallel orientation Average degree of magnet orientation: 97% Arrangement: Two magnets arranged in a V-shape. <Sample B> Magnet shape as viewed from the first direction: Arc shape (corresponding to a convex curved shape) Area of ​​the main surface of the magnet: 96.8 mm ２ (The radius of curvature of the outer arc was 25.4 mm, the radius of curvature of the inner arc was 21 mm, the outer and inner arcs were concentric, and both had a central angle of 54.3°) Magnet orientation: Parallel orientation Average degree of magnet orientation: 88% Arrangement: Two magnets were arranged in an arc shape. <Sample C> Magnet shape as viewed from the first direction: Arc shape (corresponding to a convex curved shape) Area of ​​the main surface of the magnet: 96.8 mm ２ (The radius of curvature of the outer arc is 25.4 mm, the radius of curvature of the inner arc is 21 mm, the outer arc and the inner arc are concentric, and both have a central angle of 54.3°) - Magnet orientation: Radial orientation - Average orientation degree of magnets: 95% - Arrangement: Two magnets were arranged in an arc shape.

[0112] The maximum magnetic flux density of sample A is 0.5388 W / m ２ The maximum magnetic flux density of sample B was 0.5521 W / m ２ The maximum magnetic flux density of sample C was 0.5729 W / m ２ Each magnetic flux density is rounded to the fifth decimal place.

[0113] Table 2 below summarizes the characteristics of "magnet shape," "average orientation," and "maximum magnetic flux density" for Sample A, Sample B, and Sample C. Each item is evaluated using the following criteria. Satisfaction of shape requirements: If the magnet shape is convexly curved, it is rated "satisfied," and if it is not convexly curved, it is rated "not satisfied." Satisfaction of orientation requirements: If the average orientation of the magnet measured using the above measurement method is 90% or more, it is rated "satisfied," and if it is less than 90%, it is rated "not satisfied." Table 2 shows that compared to Sample A, which uses a rectangular magnet (average orientation 97%, V-shaped arrangement), Sample B (average orientation 88%, arc-shaped arrangement) and Sample C (average orientation 95%, arc-shaped arrangement), which use convexly curved magnets, have high magnetic flux density despite their low average orientation. Furthermore, when comparing Sample B (average orientation 88%, arcuate arrangement) and Sample C (average orientation 95%, arcuate arrangement), both of which use convexly curved magnets, Sample C has a higher magnetic flux density than Sample B. From these results, it can be seen that the higher the average orientation of a convexly curved magnet, the more concentrated the magnetic flux density, thereby increasing the magnetic flux density. Therefore, it can be seen that a convexly curved magnet with an average orientation of 90% or more will have a higher magnetic flux density than a magnet with an average orientation of less than 90%. Sample B, which uses a convexly curved magnet, has a higher magnetic flux density than Sample A, which uses a rectangular magnet, even though it has an average orientation of 88%. Therefore, it can be seen that sufficient magnetic flux density can be achieved when the magnet is convexly curved and the average orientation is 90% or more.

[0114]

[0115] Furthermore, in the magnet laminate 110, the insulating layer 113 is primarily composed of inorganic crystals, so eddy current loss is unlikely to change. The reason for this is presumed to be as follows. However, the present disclosure is not limited to this presumption. The insulating layer 113, which is primarily composed of inorganic crystals, shows almost no change in resistance value in the range from room temperature (e.g., 25°C) to 150°C, so it is presumed that it is possible to reduce eddy current loss over a wide temperature range. Furthermore, since the insulating layer 113, which is primarily composed of inorganic crystals, has a thermal expansion coefficient close to that of the magnet 111, it is thought that the insulating layer 113 is unlikely to change in quality even through thermal cycling. Note that the difference in thermal expansion coefficient between the insulating layer 113 and the magnet 111 is ±3.0 x 10 －５ / K or less. For this reason as well, it is presumed that the durability (heat resistance) of the magnet laminate 110 of this embodiment is improved.

[0116] The magnet stack 110 of this embodiment has an insulating layer 113 between the magnets 111, 111. With this configuration, the insulating layer 113, which is primarily composed of inorganic crystals, can bond (adhere) the magnets 111, 111 with sufficient strength. Furthermore, because the insulating layer 113 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, if amorphous glass were used for the insulating layer, as opposed to this embodiment, there is a concern that the magnets may oxidize and lose their magnetic properties. On the other hand, because the insulating layer 113 of this embodiment is primarily composed of inorganic crystals, the magnetic properties of the magnets 111 can be suitably maintained. [Example]

[0117] The second embodiment of the present disclosure will be described in more detail below with reference to examples.

[0118] 1. Fabrication of Laminated Magnets <Experimental Examples 1C to 16C> (1) SC Alloy Preparation Step The main raw materials of an Nd / Pr alloy, an alloy containing Co, Al, Cu, Ga, and Zr, and a single metal were mixed to form 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.

[0119] (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.

[0120] (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.

[0121] (4) Fine pulverization step, second lubricant addition step The SC alloy powder after adding the lubricant was finely pulverized in a nitrogen atmosphere using a jet mill. The average particle size D50 after fine pulverization was 2.0 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.

[0122] (5) Powder Filling Process, Orientation Process, and Compaction Process: The SC alloy powder after the pulverization process and the second lubricant addition process was filled into each molding space of a mold equipped with multiple partition plates in a nitrogen atmosphere. Each compact formed in each molding space corresponds to each magnet to be stacked in a subsequent process. The planar shape of each "magnet 111" was an arc shape with a central angle of 180°, with the curve C1 having a radius of curvature of 15 mm and the opposing line C2 having a radius of curvature of 12 mm, and the curve C1 and the opposing line C2 being concentric. 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. At this time, a radial magnetic field (a magnetic field in which magnetic lines of force radiate) was used. The SC alloy powder filled in the mold was pressed 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%.

[0123] (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.

[0124] (7) Insulating Layer Coating Step After the first firing step, the partition plates were removed from the magnets to be fired, and the raw material for the insulating layer was coated on six surfaces of the magnets before lamination. The raw material for the insulating layer consisted of the compound powders of the main components listed in Table 3 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.

[0125] (8) Laminate Temporarily Fixing Process 25 magnets coated with an insulating layer were stacked in air and temporarily fixed. The number of magnets stacked was adjusted so that the dimension of the laminated magnet in the stacking direction was 50 mm. This method allows for the production of plate-shaped magnets without the need for a cutting process or other process to cut out plate-shaped magnets from a larger magnet.

[0126] (9) Hot Pressing Step The temporarily fixed laminate was placed in a hot press mold and subjected to uniaxial hot pressing. The hot pressing conditions for each of Experimental Examples 1C to 16C were as shown in Table 3. In Table 3, "vac" in the "atmosphere" section indicates vacuum, and "Ar" indicates argon atmosphere. The hot pressing time was 1 second to 1 hour, and the hot pressing heat treatment time was 10 minutes to 20 hours. In this manner, laminated magnet samples for each of Experimental Examples 1C to 16C were produced.

[0127] <Experimental Examples 1D to 5D> In Experimental Examples 1D to 5D, 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) to (6) and (8) described above for Experimental Examples 1C to 16C, and laminated magnet samples for Experimental Examples 1D to 5D were produced.

[0128] In Experimental Examples 1D to 5D, 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 3 was applied.

[0129] In Experimental Examples 1D to 5D, in the pressing step, the temporarily fixed laminate was placed in a press mold and pressed under uniaxial pressure. The pressing conditions for each of Experimental Examples 1D to 5D were as shown in Table 3. In Table 3, "air" under "atmosphere" indicates atmospheric conditions.

[0130] 2. Characteristics of Experimental Examples 1C to 16C and Experimental Examples 1D to 5D Table 3 summarizes the characteristics of the magnets and insulating layers of Experimental Examples 1C to 16C and Experimental Examples 1D to 5D. The "Type" column of "Magnet" indicates the type of magnet. "Neodymium magnet" means Nd ２ Fe １４This indicates that the magnet has B as the main phase. The "Average Orientation" column indicates the average orientation measured using the method described in the embodiment. The "Main Component" column of the "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. In Experimental Examples 1C to 16C and Experimental Examples 1D to 5D, the content (mass %) of the main component was 65% or more when the entire insulating layer was taken as 100% by mass. The amount (mass %) of inorganic crystals was calculated by determining the presence of inorganic crystals using micro X-ray analysis or XRD analysis and combining this with the compositional analysis using EPMA. In Experimental Examples 1D to 5D, components other than inorganic crystals in the insulating layer were considered to be the main component, and the content of the main component was calculated by subtracting the amount (mass %) of inorganic crystals from 100 (mass %). The "Thickness" column of the "Insulating Layer" indicates the thickness of the insulating layer. The thickness of the insulating layer was measured by observing the cross section of the laminated magnet with a SEM (scanning electron microscope). The "number of divisions" column for "laminated magnet" indicates the number of layers of the "magnet," as described above.

[0131]

[0132] 3. Performance Evaluation (1) Evaluation Method for Eddy Current Loss (25°C, 1 kHz) The eddy current loss was measured for Experimental Examples 1C to 16C and Experimental Examples 1D to 5D at 25°C and 1 kHz. Specifically, each sample of Experimental Examples 1C to 16C and Experimental Examples 1D to 5D 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.

[0133] 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

[0134] (2) Thermal Cycle Test The following thermal cycle test was conducted to evaluate the heat resistance of Experimental Examples 1C to 16C and Experimental Examples 1D to 5D. The thermal cycle consisted of a low temperature of 25°C and a high temperature of 180°C (1 minute) per cycle, and the number of thermal cycles was 1,000. The bending strength (MPa) of each sample after the test was measured in accordance with JIS R1664:2004. The bending strength (MPa) of the sample before the test was set to 100%, and the reduction rate (%) of the bending strength of the sample after the test was calculated. A low reduction rate (%) of the bending strength of the sample after the test is one indicator of high durability (heat resistance).

[0135] The evaluation was made as follows: "A": The rate of decrease in bending strength was 5% or less; "B": The rate of decrease in bending strength was more than 5% and less than 12%; "C": The rate of decrease in bending strength was more than 12%.

[0136] (3) Method for Evaluating Eddy Current Loss (150°C, 1 kHz) The eddy current losses of Experimental Examples 1C to 16C and Experimental Examples 1D to 5D were measured at 150°C and 1 kHz under the same conditions as those for the eddy current loss (25°C, 1 kHz) described above, except for the temperature. The eddy current loss at 25°C and 1 kHz was set as 100%, and the rate of change (%) of the eddy current loss at 150°C and 1 kHz was calculated.

[0137] The evaluation was made as follows: "A": rate of change in eddy current loss is 5% or less; "B": rate of change in eddy current loss is more than 5% and less than 10%; "C": rate of change in eddy current loss is more than 10%

[0138] 4. Evaluation Results The evaluation results are also shown in Table 3. Experimental Examples 1C to 16C satisfy the following requirements (a) to (d). In contrast, Experimental Examples 1D and 3D to 5D do not satisfy requirement (d). Experimental Example 2D does not satisfy requirements (c) and (d). Requirement (a): The magnet is a laminated magnet in which multiple magnets and insulating layers are stacked in a first direction. Requirement (b): The magnet contains a rare earth element and has a curved shape that is convex in a second direction when viewed from the first direction. Requirement (c): The average degree of orientation of each 1 mm wide portion centered on the normal line at multiple points from one end to the other end of the curve on the convex side in the second direction on the outer periphery of the magnet when viewed from the first direction is 90% or more. Requirement (d): The insulating layer is primarily composed of inorganic crystals.

[0139] For Experimental Examples 1C to 16C, the eddy current loss at 25°C and 1 kHz was evaluated as either "A" or "B," and the eddy current loss at 150°C and 1 kHz was evaluated as either "A" or "B." This suggests that Experimental Examples 1C to 16C can reduce eddy current loss.

[0140] Furthermore, among Experimental Examples 1C to 16C, Experimental Examples 1C to 3C, which further satisfied the following requirement (e), received an "A" rating in the evaluation of eddy current loss at 25°C and 1 kHz, the evaluation in the thermal cycle test, and the evaluation of eddy current loss at 150°C and 1 kHz. It was suggested that by satisfying requirement (e), eddy current loss can be further reduced and eddy current loss is less likely to change. Requirement (e): Contains a fluoride of Group 2A of the Periodic Table as the inorganic crystal.

[0141] 5. Effects of Examples Experimental Examples 1C to 16C were able to reduce eddy current loss generated inside. Furthermore, Experimental Examples 1C to 16C had an average degree of orientation of 90% or more, which allowed for magnetic flux concentration.

[0142] 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.

[0143] (Notes in the second embodiment) This specification includes the following inventions: [1] A laminated magnet in which a plurality of magnets and insulating layers are stacked in a first direction, wherein the magnets contain a rare earth element and have a curved shape that is convex in a second direction when viewed from the first direction, and the average degree of orientation of each 1 mm wide portion centered on a normal line at a plurality of points on the curved surface on the convex side in the second direction from one end to the other of the outer periphery of the magnet when viewed from the first direction is 90% or more, and the insulating layer is composed mainly of inorganic crystals.

[0144] <<Third Embodiment>> A third embodiment of the present disclosure will be described in detail below. In the third embodiment, when a numerical range is indicated using "-", both the lower limit and the upper limit are included unless otherwise specified. For example, the expression "10-20" includes both the lower limit "10" and the upper limit "20". In other words, "10-20" has the same meaning as "10 or more and 20 or less". Furthermore, 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 stack 210. One direction perpendicular to the Z-axis direction is 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 the Y-axis direction.

[0145] 1. Magnet Laminate 210 As shown in Figures 24 to 26, magnet laminate 210 is a magnet laminate formed by stacking multiple magnets 211 and insulating layers 213. Magnet 211 includes a crystalline phase containing rare earth elements and iron elements. The total amount of rare earth elements in magnet 211 is 27% by mass or more and 31.0% by mass or less. As shown in Figures 27 and 28, magnet 211 has a surface layer 217 of a rare earth-rich phase that contains a higher amount of rare earth elements than the crystalline phase.

[0146] (1) Magnet 211 The magnet 211 is a permanent magnet containing a rare earth element. From the viewpoint of having good magnetic properties, the magnet 211 is preferably a rare earth sintered magnet.

[0147] The composition of magnet 211 is not particularly limited as long as it contains a crystalline phase containing rare earth elements and iron. From the viewpoint of increasing magnetic flux density, the total amount of rare earth elements in magnet 211 is 31.0% by mass or less, and preferably 29.5% by mass or less. The lower limit of the total amount of rare earth elements in magnet 211 is 27% by mass or more, and may be, for example, 28% by mass or more, or 28.5% by mass or more. The total amount of rare earth elements in magnet 211 can be measured by fluorescent X-ray 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 211 and insulating layer 213.

[0148] The magnet 211 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.

[0149] 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 211, and more preferably 0.5% to 1.5% by mass.

[0150] 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 Fe content (mass %) 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 211, more preferably 65 mass % or more. The upper limit of the transition metal element content is not particularly limited, and can be, for example, 73 mass % or less of the entire magnet 211. 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 Co content can be greater than 0 mass % and less than 1 mass %.

[0151] Magnet 211 may contain elements other than the above elements (hereinafter also referred to as "other elements"). Examples of other elements include one or more elements 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 the other elements is preferably 0% to 3% by mass of the entire magnet 211.

[0152] From the viewpoint of improving coercivity, it is more preferable that the magnet 211 has a region in which the concentration of the heavy rare earth element decreases from at least a portion of the surface of the magnet 211 toward the interior of the magnet 211. FIG. 30 is a cross-sectional view of Alternative Example 1 of the magnet laminate 210, and FIG. 31 is an enlarged view of a portion of FIG. 30. In FIG. 31, the decrease in concentration of the heavy rare earth element is represented by the shade of the shading. Areas with high concentrations of the heavy rare earth element are indicated by dark shading, while areas with low concentrations are indicated by light shading. A configuration having a region in which the concentration of the heavy rare earth element decreases can contribute to reducing the amount of heavy rare earth element added while maintaining magnetic properties. The heavy rare earth element can be one or more elements selected from the group consisting of terbium (Tb), dysprosium (Dy), gadolinium (Gd), holmium (Ho), europium (Eu), thulium (Tm), ytterbium (Yb), and lutetium (Lu). Among these, the heavy rare earth element is preferably one or more of Dy and Tb. The region in magnet 211 where the concentration of the heavy rare earth element is reduced can be formed, for example, by applying a raw material containing the heavy rare earth element to the surface of magnet 211 and then heat treating it. Details will be explained later.

[0153] The magnet 211 includes a crystalline phase containing a rare earth element and an iron element. The magnet 211 usually includes the crystalline phase as a main phase. The crystalline phase containing a rare earth element and an iron element is, for example, Nd ２ Fe １４ The magnet 211 has a rare earth-rich phase that has a higher rare earth element content than the crystalline phase. The magnet 211 may also have a boron-rich phase that has a higher boron content than the crystalline phase. The crystalline 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 211 can be identified as the component with the largest peak intensity by X-ray diffraction (XRD) analysis of the magnet 211. ２ Fe １４ When the peak intensity of B is the largest, the magnet 211 is Nd ２ Fe １４ It can be determined that the main phase is B.

[0154] The average orientation of magnet 211 is the same as the explanation in the "(1.2) Average Orientation of Magnet 11" column of the first embodiment, and the description in this column applies as is. The shape of magnet 211 is the same as the explanation in the "(1.3) Shape of Magnet 11" column of the first embodiment, and the description in this column applies as is. The thickness of magnet 211 is the same as the explanation in the "(1.4) Thickness of Magnet 11" column of the first embodiment, and the description in this column applies as is.

[0155] (2) Insulating Layer 213 The insulating layer 213 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 213. The insulating layer 213 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 inorganic crystal content in the insulating layer 213 is 50% by mass or more. The inorganic crystal content in the insulating layer 213 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 213 can be analyzed by the following method. The presence of inorganic crystals is determined by X-ray microanalysis or XRD analysis, and the inorganic crystal content is calculated in combination with composition analysis using an EPMA (Electron Probe Micro Analyser).

[0156] The insulating layer 213 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 , TiB２ , Pr ２ O ３ From the viewpoint of reducing eddy current loss, the insulating layer 213 preferably contains at least a fluoride of Group 2A of the periodic table as an inorganic crystal. The insulating layer 213 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 213 contains at least one selected from the group consisting of CaF ２ It is particularly preferable that the insulating layer 213 contains 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more of a fluoride of Group 2A of the periodic table as an inorganic crystal, when the entire inorganic crystal is taken as 100% by mass. 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% by mass.

[0157] When the insulating layer 213 is primarily composed of a Group 2A fluoride, the raw material for the insulating layer 213 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 213 contains the above-mentioned heavy rare earth element compound, the heavy rare earth element can be favorably diffused into the magnet 211. The heavy rare earth element contained in the raw material for the insulating layer 213 diffuses into the magnet 211 after heat treatment. Therefore, the insulating layer 213 of the resulting magnet laminate 210 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 213 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 213 can be, for example, 20:80-40:60.

[0158] The state and arrangement of the insulating layer 213 are the same as those explained in the section "(2.2) State and arrangement of the insulating layer 13" in the first embodiment, and the description in this section applies as is. The thickness of the insulating layer 213 is the same as those explained in the section "(2.3) Thickness of the insulating layer 13" in the first embodiment, and the description in this section applies as is.

[0159] (3) Configuration of the Magnet Stack 210 From the viewpoint of reducing eddy current loss, it is preferable that 10 or more magnets 211 are used per 50 mm of the dimension of the magnet stack 210 in the first direction, preferably 20 or more magnets, and preferably 25 or more magnets are used. There is no particular upper limit on the number of magnets, and it may be, for example, 42 or less.

[0160] (4) Requirements for the Surface Layer 217 As shown in FIGS. 27 and 28 , the magnet 211 has a surface layer 217. The surface layer 217 is composed of a rare-earth-rich phase 17A, which is hatched in the figure. The surface layer 217 may be composed solely of the rare-earth-rich phase 17A, as shown in FIG. 28 . Alternatively, the surface layer 217 may contain, in addition to the rare-earth-rich phase 17A, inorganic crystalline particles 214, as shown in FIG. 27 . The rare-earth-rich phase 17A contains a higher rare-earth element content than the crystalline phase containing rare-earth elements and iron (e.g., crystalline phase particles 219). This configuration can ensure better insulation between the magnets 211 and improve eddy current loss compared to a configuration without the surface layer 217. The rare-earth element contained in the rare-earth-rich phase 17A is typically the same type as at least one of the rare-earth elements contained in the crystalline phase. For example, when the main component of the rare earth element contained in the crystalline phase is Nd, the rare earth rich phase 17A becomes a Nd rich phase.

[0161] In general, the lower the total amount of rare earth elements in the magnet 211, the less likely it is that the surface layer 217 of the rare earth-rich phase 17A will form. The reason for this is presumed to be as follows: The lower the total amount of rare earth elements in the magnet 211, the less likely it is that rare earth-rich components derived from the crystalline phase will flow to the surface of the magnet 211. The present inventors have newly discovered that the surface layer 217 of the rare earth-rich phase 17A can be formed by hot pressing even in a magnet stack 210 using magnets 211 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 surface layer 217 of the rare earth-rich phase 17A by hot pressing will be described later.

[0162] The surface layer 217 of the magnet 211 shown in Figure 27 is located on the main surface 11A side. This surface layer 217 is in contact with the insulating layer 213. When the surface layer 217 is in contact with the insulating layer 213, as described above, the surface layer 217 may be composed of, for example, inorganic crystal particles 214 in addition to the rare earth-rich phase 17A. Examples of the inorganic crystal particles 214 include the above-mentioned particles of Group 2A fluoride of the periodic table. The surface layer 217 of the magnet 211 shown in Figure 28 is located on the side surface 11B side. This surface layer 217 is not in contact with the insulating layer 213. The presence of the surface layer 217 in the magnet 211 can be confirmed, for example, by subjecting a cross section of the magnet laminate 210 to micro X-ray analysis or XRD analysis in combination with composition analysis by EPMA.

[0163] The thickness of the surface layer 217 is not particularly limited. From the viewpoint of reducing eddy current loss, the thickness of the surface layer 217 is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 25 μm or more. There is no particular upper limit to the thickness of the surface layer 217, and it is usually 40 μm or less. The thickness of the surface layer 217 can be measured, for example, by subjecting a cross section of the magnet laminate 210 to X-ray microanalysis or XRD analysis in combination with composition analysis by EPMA.

[0164] (5) Requirements for Volume Resistivity The volume resistivity in the first direction of the magnet laminate 210 is preferably 100 Ω·cm or more and 2000 Ω·cm or less. A volume resistivity in this range is suitable for various applications such as motors. From the viewpoint of reducing eddy current loss, the lower limit of the volume resistivity is preferably 400 Ω·cm or more, more preferably 800 Ω·cm or more, and even more preferably 1200 Ω·cm or more. The volume resistivity is measured in accordance with JIS C2139:2008. The volume resistivity can be controlled by the volume resistivity of the insulating layer 213 itself, the number of insulating layers 213, etc. For example, using insulating layers 213 with high volume resistivity tends to increase the volume resistivity, while using insulating layers 213 with low volume resistivity tends to decrease the volume resistivity. Furthermore, increasing the number of insulating layers 213 tends to increase the volume resistivity, while decreasing the number of insulating layers 213 tends to decrease the volume resistivity.

[0165] (6) Requirements for the Subphase of Inorganic Crystal From the viewpoint of reducing eddy current loss, improving moisture resistance, and improving heat resistance, it is preferable that the inorganic crystal of the insulating layer 213 has a periodic table Group 2A fluoride as a main phase and one or more types selected from the group consisting of oxides of rare earth elements and nitrides of rare earth elements (hereinafter also referred to as oxides of rare earth elements, etc.) as a subphase.

[0166] The oxides of rare earth elements include Dy ２ O ３ , Tb ２ O ３ , Nd ２ O ３ , and Pr ２ O ３Examples of rare earth element nitrides include one or more selected from the group consisting of DyN, TbN, NdN, and PrN. Such rare earth element oxides can be formed by oxidizing a portion of the rare earth elements that have seeped out of the magnet 211 during hot pressing, which will be described later. Examples of rare earth element nitrides include one or more selected from the group consisting of DyN, TbN, NdN, and PrN. Such rare earth element nitrides can be formed, for example, by nitriding a portion of the rare earth elements that have seeped out of the magnet 211 during hot pressing, which will be described later. The presence of rare earth element oxides can be confirmed, for example, by subjecting a cross section of the magnet laminate 210 to micro X-ray analysis or XRD analysis in combination with composition analysis by EPMA.

[0167] The content of the rare earth element oxide or the like is not particularly limited. When the entire inorganic crystal is taken as 100 mass%, the content of the rare earth element oxide or the like is preferably 5 mass% or less, more preferably 3 mass% or less, and even more preferably 1 mass% or less. The content of the rare earth element oxide or the like may be 0 mass%. The content of the rare earth element oxide or the like can be controlled by adjusting the oxygen partial pressure and nitrogen partial pressure during hot pressing and maintaining a predetermined temperature for a predetermined time during the temperature drop process. If the oxygen partial pressure during hot pressing is high, the content of the rare earth element oxide tends to be high. If the oxygen partial pressure during hot pressing is low, the content of the rare earth element oxide tends to be low. Furthermore, if the nitrogen partial pressure during hot pressing is high, the content of the rare earth element nitride tends to be high. If the nitrogen partial pressure during hot pressing is low, the content of the rare earth element nitride tends to be low. To form an oxide of a rare earth element, the temperature may be lowered, for example, by holding the material at 250°C to 350°C for 12 to 20 minutes. To form a nitride of a rare earth element, the temperature may be lowered, for example, by holding the material at 600°C to 800°C for 12 to 20 minutes.

[0168] (7) Requirements for the angle of the magnets As shown in Figure 29, when three or more magnets 211 are used and the magnets 211 are plate magnets 211 having an upper bottom surface 11A1, a lower bottom surface 11A2, and side surfaces 11B, the magnets 211 are preferably arranged as follows: The upper bottom surface 11A1 and the lower bottom surface 11A2 of one plate magnet 211 are flat surfaces that extend approximately parallel to each other. In the following description of the magnet stack 210 in Figure 29, the topmost magnet 211 located at the top is designated by the symbol 2111, the bottommost magnet 211 located at the bottom is designated by the symbol 2113, and each intermediate magnet 211 excluding the topmost magnet 2111 and the bottommost magnet 2113 is designated by the symbol 2112. In the magnet stack 210, it is preferable that the angle formed between the lower bottom surface 11A2 of the top magnet 2111, which is located at the top of the plate magnets 211, and the lower bottom surface 11A2 of each intermediate magnet 2112 is 3° or less. The above angle is more preferably 2.5° or less, and even more preferably 2.2° or less. The angle formed between the lower bottom surface 11A2 of the top magnet 2111 and the lower bottom surface 11A2 of each intermediate magnet 2112 is 0° or more. An angle of 0° formed between the lower bottom surface 11A2 of the top magnet 2111 and the lower bottom surface 11A2 of the intermediate magnet 2112 indicates that the top magnet 2111 and the intermediate magnets 2112 are arranged approximately parallel to each other.

[0169] The angle formed between the lower bottom surface 11A2 of the top magnet 2111 and the lower bottom surface 11A2 of the intermediate magnets 2112 can be calculated by image analysis of the cross-sectional observation images of the magnet stack 210. In any of the multiple cross-sectional observation images (for example, two cross-sectional observation images), the angle between the lower bottom surface 11A2 of the top magnet 2111 and the lower bottom surface 11A2 of each intermediate magnet 2112 is calculated, and if all angles are 3° or less, it is determined that the angle formed between the lower bottom surface 11A2 of the top magnet 2111 located at the top and the lower bottom surface 11A2 of each intermediate magnet 2112 is 3° or less.

[0170] The fact that the above angle is 3° or less is one indicator that the plate magnets 211 are arranged approximately parallel. With a configuration in which the above angle is 3° or less, the orientation direction of the plate magnets 211 can be aligned, improving the magnetic flux density of the magnet stack 210. Note that the angle between the lower bottom surface 11A2 of the top magnet 2111 and the lower bottom surface 11A2 of each intermediate magnet 2112 can be reduced by, for example, performing a hot pressing process to make the thickness of the insulating layer 213 between the magnets 211 uniform.

[0171] 2. Manufacturing Method of Magnet Laminate 210 The manufacturing method of the magnet laminate 210 is the same as that explained in the section "2. Manufacturing Method of Rare Earth Magnet 10" in the first embodiment, and the description in this section applies as is.

[0172] The magnet stack 210 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 of the insulating layer 213 is sandwiched between at least a pair of magnets 211, 211 (sintered bodies of SC alloy), and applying pressure in a direction that crushes the raw material of the insulating layer 213. Alternatively, the magnet stack 210 can be considered to be a magnet stack manufactured by arranging a first magnet 211 (sintered body of SC alloy), the raw material of the insulating layer 213, and a second magnet 211 (sintered body of SC alloy) in this order to form a laminate, and then applying pressure to the first magnet 211 and the second magnet 211 from both sides while heating the laminate. The raw material of the insulating layer 213 preferably contains inorganic crystals. The raw material of the insulating layer 213 may further contain a component containing a heavy rare earth element. For example, the raw material of the insulating layer 213 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 %.

[0173] 3. Uses of the Magnet Laminate 210 The uses of the magnet laminate 210 are not particularly limited. The magnet laminate 210 is suitable as a magnet for a motor. The magnet laminate 210 has low eddy current loss generated internally and is resistant to deterioration over time, 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 213 of the magnet laminate 210 is primarily composed of inorganic crystals, its insulating performance is less susceptible to changes due to the influence of humidity, temperature, and deterioration over time than insulating layers made of resin or the like. Therefore, the magnet laminate 210 is useful for various applications where resistance to changes in insulating performance is desired. For details of the motor, please refer to the first embodiment, and a description thereof will be omitted.

[0174] 4. Actions and Effects of the Present Embodiment The magnet laminate 210 of the present embodiment can reduce eddy current loss generated internally and is resistant to deterioration over time. The reasons for this are presumed to be as follows. However, the present disclosure is not limited to this presumption. Because the total rare earth element content of magnet 211 is 31.0 mass% or less, it is presumed that magnetic flux density can be ensured even in high-temperature environments such as 100°C. Furthermore, because magnet 211 has a rare-earth-rich phase surface layer 217 that contains a higher rare earth element content than the crystalline phase, it is presumed that this can contribute to one or more of the following: That is, it is presumed that it can contribute to reducing eddy current loss, improving moisture resistance, and reducing strength change after thermal cycling. Furthermore, rare-earth-rich phase surface layer 217 is less likely to deteriorate the magnetic properties of magnet 211 than, for example, a surface layer made of inorganic oxide, etc., and can also contribute to ensuring magnetic properties.

[0175] Furthermore, when ten or more magnets 211 are used per 50 mm of the magnet stack 210 in the first direction, eddy current loss can be further reduced. Furthermore, when the insulating layer 213 is primarily composed of inorganic crystals, it is even less susceptible to deterioration over time. 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 213 primarily composed of inorganic crystals exhibits 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 213 primarily composed of inorganic crystals has a thermal expansion coefficient close to that of the magnets 211, it is believed that the insulating layer 213 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 stack 210 of this embodiment is improved.

[0176] Furthermore, when the inorganic crystal has a fluoride of Group 2A of the periodic table as a main phase and one or more subphases selected from the group consisting of oxides of rare earth elements and nitrides of rare earth elements, it is possible to expect reduced eddy current loss, improved moisture resistance, and reduced change in strength after thermal cycling.

[0177] Furthermore, if the magnet stack 210 satisfies the above requirement (7) regarding the angle of the magnets, the magnetic flux density of the magnet stack 210 can be further improved.

[0178] The present disclosure will be explained in more detail below with reference to examples.

[0179] 1. Fabrication of Magnet Laminates The "magnet laminates" are made by stacking multiple "magnets 211," and the number of "magnets 211" laminated in each of Experimental Examples 1E to 20E and Experimental Examples 1F to 6F is shown as the "number of divisions" in Table 5. The total thickness (dimension in the stacking direction) of each magnet laminate is set to 50 mm. Therefore, each magnet laminate is stacked with the number of "magnets 211" divided as shown in Table 5 per 50 mm of thickness. In other words, each magnet laminate is divided into the number of magnets divided as shown in Table 5 per 50 mm of thickness.

[0180] <Experimental Examples 1E to 20E, and 2F> (1) SC Alloy Preparation Step The main raw materials of an 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.

[0181] (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.

[0182] (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.

[0183] (4) Fine pulverization step, second lubricant addition step The SC alloy powder after adding the lubricant was finely pulverized in a nitrogen atmosphere using a jet mill. The average particle size D50 after fine pulverization was 2.0 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.

[0184] (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%.

[0185] (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.

[0186] (7) Insulating Layer Coating Step After the first firing step, the partition plates were removed from the fired 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 was a mixture of powders of compounds A, B, and C listed in Table 4, and a solvent. TbF ３ Compound powder or DyF ３ The ratio of the compound powder was 0 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.

[0187] (8) Laminate Temporarily Fixing Process The magnets coated with the insulating layer were stacked in the air to the number of divisions shown in Table 5, and temporarily fixed. The number of layers 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.

[0188] (9) Hot Pressing Step The temporarily fixed laminate was placed in a hot press mold and subjected to uniaxial hot pressing. This step was carried out under a vacuum atmosphere (for example, 10 －３ Pa-10 －４ The hot pressing was performed under an inert atmosphere (nitrogen atmosphere, argon atmosphere), or air. The hot pressing temperature was 700°C to 1100°C, the hot pressing pressure time was 1 second to 1 hour, the hot pressing pressure was 3 MPa to 100 MPa, and the hot pressing heat treatment time was 10 minutes to 20 hours. As a result, laminated magnet samples were produced for Experimental Examples 1E to 20E and Experimental Example 2F. Note that, during the cooling process after the hot pressing step, if the sample was held at 650°C for 15 minutes in a nitrogen atmosphere, nitrides of rare earth elements were formed. Furthermore, during the cooling process after the hot pressing step, if the sample was held at 300°C for 15 minutes in air, oxides of rare earth elements were formed. Experimental Examples 9E to 20E, among Experimental Examples 1E to 20E, were held during one of the above cooling processes. Among Experimental Examples 1E to 20E, Experimental Examples 1E to 8E did not maintain the temperature at a predetermined temperature during the temperature drop process.

[0189] <Experimental Example 1F> Experimental Example 1F is an example in which the above-mentioned (9) hot pressing step was not performed. In Experimental Example 1F, after forming magnets in the same manner as steps (1) to (6) above, a very thin layer of adhesive was applied to the magnet surfaces, and the raw material for the insulating layer was applied between adjacent magnets to join the magnets together, thereby producing a laminated magnet sample. Note that when the above-mentioned (9) hot pressing step is performed, a surface layer is formed on the magnet, but since the hot pressing step was not performed in Experimental Example 1F, no surface layer was formed on the magnet.

[0190] <Experimental Examples 3F to 6F> In Experimental Examples 3F to 6F, 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) to (6) and (8) described above for Experimental Examples 1E to 20E and Experimental Example 2F, and laminated magnet samples for Experimental Examples 3F to 6F were produced.

[0191] In Experimental Examples 3F to 6F, 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 4 was applied.

[0192] In Experimental Examples 3F to 6F, in the pressing step, the temporarily fixed laminate was placed in a press mold and pressed uniaxially. This step was carried out in an air atmosphere. The pressing temperature was 25°C, the pressing time was at least the time required for the resin to harden, and the pressing pressure was 3 MPa.

[0193] 2. Characteristics of Experimental Examples 1E to 20E and Experimental Examples 1F to 6F Tables 4 and 5 summarize the characteristics of the magnets and insulating layers of Experimental Examples 1E to 20E and Experimental Examples 1F to 6F. 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 "Presence or Absence of Surface Layer" column under "Magnet" indicates "Present" if a surface layer of rare earth-rich phase is present, and "Absent" if no surface layer of rare earth-rich phase is present.

[0194] The "Component: A" column under "Insulating Layer" indicates the compound contained in the insulating layer in the largest amount (mass %). The "Component: B" and "Component: C" columns under "Insulating Layer" indicate compounds other than "Component: A" contained in the insulating layer. The inorganic crystal content (mass %) indicates the inorganic crystal content (mass %) when the entire insulating layer is taken as 100 mass %. The presence of inorganic crystals was determined by X-ray microanalysis or XRD analysis and calculated in combination with EPMA composition analysis. In Experimental Examples 1E to 20E, 1F, and 2F, "Component: A," "Component: B," and "Component: C" exist as inorganic crystals, and the "inorganic crystal content" is the sum of the "Content of A," "Content of B," and "Content of C." For Experimental Examples 3F to 6F, the inorganic crystal content was not calculated. In the "Oxide / Nitride" column, if one or more subphases selected from the group consisting of oxides of rare earth elements and nitrides of rare earth elements are present, it is marked "Present," and if the above subphases are not present, it is marked "Absent." If this "Oxide / Nitride" is "Present," the above requirement (6) for inorganic crystalline subphases (requirement (e) described below) is met.

[0195] The "Number of divisions" column indicates the number of layers of the "magnet 211" as described above. The "Volume resistivity" column indicates the volume resistivity of the magnet, measured using the method described in the embodiment. The volume resistivity was measured at 25°C based on JIS C2139:2008. The "Magnet angle" column indicates the largest angle between the lower base surface of the top magnet and the lower base surface of each intermediate magnet, measured using the method described in the embodiment. If the angle listed in this "Magnet angle" column is 3° or less, the above (7) requirement regarding the magnet angle (requirement (f) described below) is met.

[0196]

[0197]

[0198] 3. Performance Evaluation (1) Evaluation Method for Eddy Current Loss (100°C, 1 kHz) The eddy current loss of Experimental Examples 1E to 20E and Experimental Examples 1F to 6F was measured at 100°C and 1 kHz. Specifically, each sample of Experimental Examples 1E to 20E and Experimental Examples 1F to 6F 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.

[0199] The evaluation was made as follows: Eddy current loss (100°C, 1 kHz) "AA"...80 W / kg or less "A"...greater than 80 W / kg and less than 90 W / kg "B"...greater than 90 W / kg and less than 105 W / kg "C"...greater than 105 W / kg

[0200] (2) Evaluation Method of Moisture Resistance To evaluate the moisture resistance of Experimental Examples 1E to 20E and Experimental Examples 1F to 6F, 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 (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.

[0201] 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%

[0202] (3) Thermal Cycle Test The following thermal cycle test was conducted to evaluate the heat resistance of Experimental Examples 1E to 20E and Experimental Examples 1F to 6F. The thermal cycle consisted of a low temperature of 25°C and a high temperature of 100°C (1 minute) per cycle, and the number of thermal cycles was 1,000. The bending strength (MPa) of each sample after the test was measured in accordance with JIS R1664:2004. The bending strength (MPa) of the sample before the test was set to 100%, and the reduction rate (%) of the bending strength of the sample after the test was calculated. A low reduction rate (%) of the bending strength of the sample after the test is one indicator of high durability (heat resistance).

[0203] The evaluation was made as follows: "A": The rate of decrease in bending strength was 5% or less; "B": The rate of decrease in bending strength was more than 5% and less than 15%; "C": The rate of decrease in bending strength was more than 15%.

[0204] (4) Evaluation method for magnetic flux density (100°C) The magnetic flux density Br (T) was measured with a pulse BH tracer at 100°C. The evaluation direction for the measurement was a direction perpendicular to the surface of the uppermost magnet for the laminated magnet.

[0205] The evaluation was as follows: "A": 1.47T or more; "B": 1.45T or more, less than 1.47T; "C": Less than 1.45T.

[0206] 4. Evaluation Results The evaluation results are also shown in Table 5. Experimental Examples 1E to 20E satisfy the following requirements (a) to (c). Requirement (a): The magnet is a laminated magnet in which multiple magnets and insulating layers are stacked in a first direction. Requirement (b): The magnet contains a crystalline phase containing rare earth elements and iron elements, 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 magnet has a surface layer of a rare earth-rich phase that contains a higher amount of rare earth elements than the crystalline phase.

[0207] In contrast, Experimental Examples 1F to 6F do not satisfy the following requirements: Experimental Examples 1F and 3F to 6F do not satisfy requirement (c); Experimental Example 2F does not satisfy requirement (b).

[0208] Experimental Examples 1E to 20E were evaluated as "AA," "A," or "B" for eddy current loss at 100°C and 1 kHz. Experimental Examples 1E to 20E were evaluated as "A" or "B" for moisture resistance. Experimental Examples 1E to 20E were evaluated as "A" or "B" for the thermal cycle test. Experimental Examples 1E to 20E were evaluated as "A" or "B" for magnetic flux density at 100°C. In contrast, Experimental Examples 2F, 3F, and 6F were evaluated as "C" for eddy current loss at 100°C and 1 kHz. Experimental Examples 1F to 3F, 5F, and 6F were evaluated as "C" for moisture resistance. Experimental Examples 1F to 6F were evaluated as "C" for the thermal cycle test. Experimental Examples 2F to 6F were evaluated as "C" for magnetic flux density at 100°C. It was suggested that Experimental Examples 1E to 20E were able to reduce eddy current loss and ensure magnetic properties equal to or better than those of Experimental Examples 3F to 6F.

[0209] Furthermore, among Experimental Examples 1E to 20E, Experimental Examples 6E to 20E, which further satisfied the following requirement (d), were evaluated as "AA" or "A" for eddy current loss at 100°C and 1 kHz. It was suggested that by satisfying requirement (d), eddy current loss can be further reduced. Requirement (d): 10 or more magnets are used per 50 mm of the dimension of the magnet stack 210 in the first direction, the insulating layer is composed mainly of inorganic crystals, and the volume resistivity of the magnet stack in the first direction is 100 Ω-cm or more and 2000 Ω-cm or less.

[0210] Furthermore, among Experimental Examples 1E to 20E, Experimental Examples 9E to 20E, which further satisfied the following requirement (e), were evaluated as "AA" for eddy current loss at 100°C and 1 kHz, "A" for moisture resistance, and "A" for the thermal cycle test. It was suggested that by satisfying requirement (e), it is possible to further reduce eddy current loss, improve moisture resistance, and reduce strength change after thermal cycling. Requirement (e): The inorganic crystal has a fluoride of Group 2A of the periodic table as the main phase, and one or more subphases selected from the group consisting of oxides of rare earth elements and nitrides of rare earth elements.

[0211] Furthermore, among Experimental Examples 1E to 20E, Experimental Examples 15E to 20E, which further satisfied the following requirement (f), were rated "A" for magnetic flux density (100°C). It was suggested that satisfying requirement (f) could further improve magnetic properties. Requirement (f): Among the plate magnets, the angle formed between the bottom surface of the topmost magnet located at the top and the bottom surface of each intermediate magnet excluding the topmost magnet and the bottommost magnet located at the bottom is 3° or less.

[0212] 5. Effects of the Examples Experimental Examples 1E to 20E were able to reduce eddy current loss generated inside. Experimental Examples 1E to 20E were less susceptible to deterioration over time.

[0213] 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.

[0214] (Additional notes in the third embodiment) This specification includes the following inventions. [1] A magnet laminate formed by stacking a plurality of magnets and insulating layers, wherein the magnets include a crystalline phase containing rare earth elements and iron, the total rare earth element content of the magnets is 27% by mass or more and 31.0% by mass or less, and the magnets have a surface layer of a rare earth-rich phase having a higher rare earth element content than the crystalline phase. [2] The magnet laminate according to [1], wherein the magnets and insulating layers are stacked in a first direction, 10 or more magnets are used per 50 mm of the magnet laminate in the first direction, the insulating layers are mainly composed of inorganic crystals, and the volume resistivity of the magnet laminate in the first direction is 100 Ω·cm or more and 2000 Ω·cm or less. [3] The magnet laminate according to [2], wherein the inorganic crystals have a fluoride of Group 2A of the periodic table as a main phase and one or more subphases selected from the group consisting of oxides of the rare earth elements and nitrides of the rare earth elements. [4] The magnet laminate according to any one of [1] to [3], wherein three or more magnets are used, the magnets are plate magnets having upper and lower surfaces, and side surfaces, and the lower surface of the topmost magnet among the plate magnets forms an angle of 3° or less with the lower surface of each intermediate magnet excluding the topmost magnet and the bottommost magnet. [5] A motor having the magnet laminate according to any one of [1] to [3].

[0215] <<Fourth Embodiment>> A fourth embodiment of the present disclosure will be described in detail below. In the fourth embodiment, when a numerical range is indicated using "-", both the lower limit and the upper limit are included unless otherwise specified. For example, the expression "10-20" includes both the lower limit "10" and the upper limit "20". In other words, "10-20" has the same meaning as "10 or more and 20 or less". Furthermore, 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 stack 310. One direction perpendicular to the Z-axis direction is 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 the Y-axis direction.

[0216] 1. Laminated Magnet 310 As shown in Figures 32 to 34, the laminated magnet 310 is a laminated magnet in which plate magnets 311 containing rare earth elements and insulating bonding layers 313 (insulating layers) are alternately stacked. The plate magnets 311 are made of Nd ２ Fe １４ B is the main phase. The thickness of the plate magnet 311 is 0.5 mm or more and 4.0 mm or less. When a virtual line L1 passing through the center of gravity G1 of the magnet stack 310 and extending in the stacking direction is taken, and a cross section of the magnet stack 310 cut so that the cross-sectional area of ​​the magnet stack 310 is smallest on a virtual plane VP including the virtual line L1 is observed, a Nd-rich phase 17A having a higher Nd content than the main phase and fluoride particles 314 of a metal from Group 2A of the periodic table are present in the range from the interface between the plate magnet 311 and the insulating bonding layer 313 to a depth of 10 μm on the plate magnet side. In the first region R1 satisfying the following conditions (1) to (4), the area ratio occupied by the fluoride particles 314 is 7% or more and 22% or less. Condition (1): The first region R1 is present on the plate magnet 311 side from the interface between the plate magnet 311 and the insulating bonding layer 313. Condition (2): The first region R1 is a rectangle that is 10 μm in the stacking direction and 50 μm in the direction perpendicular to the stacking direction. Condition (3): When a line L2 is drawn that passes through the center of gravity G2 of the planar figure of the plate magnet 311 that appears in the cross section and extends in the stacking direction, the center CT1 of the rectangle lies on the line L2. Condition (4): The rectangle is in contact with the insulating bonding layer 313.

[0217] (1) Plate Magnet 311 The plate magnet 311 is a permanent magnet containing a rare earth element. From the viewpoint of having good magnetic properties, the plate magnet 311 is preferably a rare earth sintered magnet.

[0218] The composition of the plate magnet 311 is Nd ２ Fe １４There are no particular limitations as long as B is the main phase. From the viewpoint of increasing the magnetic flux density, the total amount of rare earth elements in the plate magnet 311 is preferably 31.0 mass% or less, and more preferably 29.5 mass% or less. The lower limit of the total amount of rare earth elements in the plate magnet 311 may be, for example, 27 mass% or more, 28 mass% or more, or 28.5 mass% or more. The total amount of rare earth elements in the plate magnet 311 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 the plate magnet 311 and the insulating bonding layer 313.

[0219] 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% by mass or more and 3% by mass or less of the entire plate magnet 311, and more preferably 0.5% by mass or more and 1.5% by mass or less.

[0220] In addition to iron (Fe), the transition metal element may include one or more elements selected from the group consisting of 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 Fe content (mass %) is the highest among the transition metal elements. The content of the transition metal element is preferably 60 mass % or more of the entire plate magnet 311, 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 plate magnet 311. 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 Co content can be greater than 0 mass % and less than 1 mass %.

[0221] The plate magnet 311 may contain elements other than the above elements (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 the other elements is preferably 0% to 3% by mass of the entire plate magnet 311.

[0222] From the viewpoint of improving coercivity, it is more preferable that the plate magnet 311 have a region in which the concentration of the heavy rare earth element decreases from at least a portion of the surface of the plate magnet 311 toward the interior of the plate magnet 311. Fig. 39 is a cross-sectional view of Alternative Example 1 of the magnet stack 310, and Fig. 40 is an enlarged view of a portion of Fig. 39. In Fig. 40, the decrease in concentration of the heavy rare earth element is represented by the shade of the shading. Areas with high concentrations of the heavy rare earth element 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 the heavy rare earth element decreases can contribute to reducing the amount of heavy rare earth element added while maintaining magnetic properties. The heavy rare earth element may be one or more elements 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 element is preferably one or more elements selected from Dy and Tb. The region in plate magnet 311 where the concentration of the heavy rare earth element decreases can be formed, for example, by applying a material containing the heavy rare earth element to the surface of plate magnet 311 and then heat treating it. Details will be described later.

[0223] The plate magnet 311 is made of Nd ２ Fe １４ The plate magnet 311 has a Nd-rich phase that has a higher Nd content than the main phase. The plate magnet 311 may further have a boron-rich phase that has a higher boron content than the crystalline phase. The crystalline 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 plate magnet 311 can be identified as the component with the largest peak intensity by XRD (X-ray diffraction) analysis of the plate magnet 311. ２ Fe １４ When the peak intensity of B is the largest, the plate magnet 311 is Nd ２ Fe １４ It can be determined that the main phase is B.

[0224] The average orientation of the plate magnet 311 is the same as that explained in the section "(1.2) Average orientation of the magnet 11" in the first embodiment, and the description in this section applies as is.

[0225] The plate magnet 311 has a shorter distance from the surface to the deepest part than a block-shaped magnet with a larger thickness. Therefore, the plate magnet 311 is suitable because it facilitates the diffusion of heavy rare earth elements into the interior when the heavy rare earth elements are diffused through grain boundaries. The plate magnet 311 can be suitably used as a laminated magnet in which multiple plate magnets 311 and insulating bonding layers 313 are stacked. The laminated magnet 310 in FIG. 32 is formed by stacking multiple plate magnets 311 with the thickness direction of the plate magnet 311 as the stacking direction. In this laminated magnet, the plate magnets 311 and insulating bonding layers 313 are stacked alternately. In a laminated magnet, each plate magnet 311 is sometimes referred to as a magnet body. Note that the plate magnets 311 in FIGS. 32 and 33 are rectangular when viewed from above (Z-axis direction). The plate magnet 311 may have a shape other than rectangular when viewed from above, and may 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 Figure 42, or the upward direction in Figure 42), as shown in Figures 41 and 42.

[0226] The thickness of each plate magnet 311 is 0.5 mm or more and 4.0 mm or less, and preferably 1.2 mm or more and 2.5 mm or less. If the thickness of the plate magnet 311 is 0.5 mm or more, it is easy to form the plate magnet 311 while ensuring an average degree of orientation. If the thickness of the plate magnet 311 is 4.0 mm or less, it is easy to diffuse the heavy rare earth element to the interior. Furthermore, if the thickness is 4.0 mm or less, eddy current loss inside the magnet stack 310 can be suitably reduced. The dimensions of the plate magnet 311 in the direction perpendicular to the thickness are not particularly limited. For example, the plate magnet 311 can have a thickness of 0.5 mm or more and 4.0 mm or less, a length of 4 mm or more and 10 mm or less, and a width of 10 mm or more and 30 mm or less.

[0227] (2) Insulating Bonding Layer 313 (Insulating Layer) The insulating bonding layer 313 is not particularly limited as long as it contains fluoride particles 314 of a metal of Group 2A of the periodic table. The insulating bonding layer 313 preferably contains inorganic crystals as its main component. Incidentally, "containing inorganic crystals as its main component" means that the content of inorganic crystals in the insulating bonding layer 313 is 50% by mass or more. The content of inorganic crystals in the insulating bonding layer 313 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 bonding layer 313 can be analyzed by the following method. The presence of inorganic crystals is determined by X-ray microanalysis or XRD analysis, and the content of inorganic crystals is calculated in combination with composition analysis by EPMA (Electron Probe Micro Analyser).

[0228] The insulating bonding layer 313 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 bonding layer 313 preferably contains at least a fluoride of Group 2A of the periodic table as an inorganic crystal. The insulating bonding layer 313 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 bonding layer 313 contains at least one selected from the group consisting of CaF２ It is particularly preferred that the composition contains:

[0229] When the total mass of the inorganic crystal is taken as 100 mass %, the insulating bonding layer 313 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 crystal. 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 %.

[0230] When the insulating bonding layer 313 is primarily composed of a Group 2A fluoride, the raw material for the insulating bonding layer 313 preferably contains the above-mentioned heavy rare earth element compound in addition to the Group 2A fluoride. If the raw material for the insulating bonding layer 313 contains the above-mentioned heavy rare earth element compound, the heavy rare earth element can be favorably diffused into the plate magnet 311. The heavy rare earth element contained in the raw material for the insulating bonding layer 313 diffuses into the plate magnet 311 after heat treatment. Therefore, the insulating bonding layer 313 of the resulting magnet laminate 310 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 bonding layer 313 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 bonding layer 313 can be, for example, 20:80-40:60.

[0231] The state and arrangement of the insulating bonding layer 331 are the same as those explained in the section "(2.2) State and arrangement of the insulating layer 13" in the first embodiment, and the description in this section applies as is. The thickness of the insulating bonding layer 331 is the same as those explained in the section "(2.3) Thickness of the insulating layer 13" in the first embodiment, and the description in this section applies as is.

[0232] (3) Configuration of the Magnet Stack 310 From the viewpoint of reducing eddy current loss, it is preferable that 10 or more plate magnets 311 are used per 50 mm of the dimension of the magnet stack 310 in the first direction, preferably 20 or more, and preferably 25 or more. There is no particular upper limit on the number of magnets, and it may be, for example, 42 or less.

[0233] (4) Requirements for Interface I Between Plate Magnet 311 and Insulating Bonding Layer 313 When an imaginary line L1 passing through the center of gravity G1 of the laminated magnet 310 and extending in the stacking direction is taken, and a cross section of the laminated magnet 310 cut so that the cross-sectional area of ​​the laminated magnet 310 is smallest is observed on an imaginary plane VP including the imaginary line L1, a Nd-rich phase 17A having a higher Nd content than the main phase, and fluoride particles 314 of a metal of Group 2A of the periodic table are present in the range from the interface I between the plate magnet 311 and the insulating bonding layer 313 to a depth of 10 μm on the plate magnet 311 side.

[0234] A cross section of the magnet laminate 310 will be specifically described with reference to FIGS. 32 to 34 . In the magnet laminate 310, an imaginary line L1 passing through the center of gravity G1 in FIG. 32 and extending in the stacking direction extends in the Z-axis direction. As shown in FIG. 33 , an imaginary plane VP cutting the magnet laminate 310 so that its cross-sectional area is smallest is the XZ plane including the imaginary line L1. Note that a cross section of the magnet laminate 310 cut along a plane that includes the imaginary line L1 and intersects with the X-axis direction has a larger cross-sectional area than a cross section cut along the XZ plane. As shown in FIG. 34 , multiple cut surfaces of the plate magnet 311 appear in the cross section cut along the imaginary plane VP. The cut surfaces of each plate magnet 311 form a rectangular planar shape. In the magnet laminate 310 of FIGS. 41 to 43 , the imaginary line L1 also extends in the Z-axis direction. The imaginary plane VP is the XZ plane including the imaginary line L1. 43, a cross section cut by the imaginary plane VP shows a plurality of cut surfaces of the plate magnet 311. Each cut surface of the plate magnet 311 forms a rectangular planar figure.

[0235] 35 is an enlarged schematic view of region R0 of the magnet stack 310 of FIG. 34. The main surface 11A (upper bottom surface 11A1 described later) of the plate magnet 311 constitutes an interface I between the plate magnet 311 and the insulating bonding layer 313. The interface I between the plate magnet 311 and the insulating bonding layer 313 can be identified by image analysis using, for example, EPMA. The Nd-rich phase 17A contains Nd ２ Fe １４The Nd-rich phase 17A has a higher Nd content than the B main phase (e.g., main phase particles 319). The Nd-rich phase 17A is, for example, layered on the surface of the plate magnet 311. At least a portion of the fluoride particles 314 of a Group 2A metal of the periodic table are contained in the layered Nd-rich phase 17A. In other words, the plate magnet 311 can be said to have a surface layer 317 of the Nd-rich phase 17A containing the fluoride particles 314. A configuration in which the Nd-rich phase 17A and the fluoride particles 314 of a Group 2A metal of the periodic table are present in a range from the interface I between the plate magnet 311 and the insulating bonding layer 313 to a depth of 10 μm on the plate magnet 311 side can be expected to have the following effects. That is, with this configuration, insulation between the plate magnets 311 can be more effectively ensured than when only the Nd-rich phase 17A is present. Therefore, eddy current loss in the magnet laminate 310 can be effectively reduced. The presence of the Nd-rich phase 17A and the fluoride particles 314 of a Group 2A metal of the periodic table can be confirmed, for example, by subjecting a cross section of the magnet laminate 310 to micro X-ray analysis or XRD analysis in combination with an EPMA composition analysis. The requirements for the interface I between the plate magnet 311 and the insulating bonding layer 313 can be met by observing multiple 50 μm × 50 μm square fields of view when observing the cross-sectional structure of the magnet laminate 310, and the requirements can be met in at least one of the fields of view.

[0236] In general, the lower the total amount of rare earth elements in the plate magnet 311, the less likely the Nd-rich phase 17A is to be present near the interface I between the plate magnet 311 and the insulating bonding layer 313. The reason for this is presumed to be as follows. That is, the lower the total amount of rare earth elements in the plate magnet 311, the less likely the Nd-rich components derived from the main phase to flow to the surface of the plate magnet 311. The present inventors have newly discovered that even in a magnet stack 310 using a plate magnet 311 with a low total amount of rare earth elements (e.g., 31.0 mass% or less), the Nd-rich phase 17A can be present near the interface I by hot pressing. Furthermore, the presently disclosed technology has been developed, in which the Nd-rich phase 17A and the fluoride particles 314 of a metal of Group 2A of the periodic table are present near the interface I by using fluoride particles 314 of a metal of Group 2A of the periodic table as the raw material for the insulating bonding layer 313. The method of making the Nd-rich phase 17A and the fluoride particles 314 of a metal of Group 2A of the periodic table present near the interface I by hot pressing will be described later.

[0237] The thickness of the surface layer 317 of the Nd-rich phase 17A containing the fluoride particles 314 is not particularly limited. From the viewpoint of reducing eddy current loss, the thickness of the surface layer 317 is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 25 μm or more. There is no particular upper limit to the thickness of the surface layer 317, and it is usually 40 μm or less. The thickness of the surface layer 317 can be measured, for example, by subjecting a cross section of the magnet laminate 310 to micro X-ray analysis or XRD analysis in combination with composition analysis by EPMA.

[0238] (5) Requirements for the Area Ratio Occupied by the Fluoride Particles 314 In the first region R1 that satisfies the following conditions (1) to (4), the area ratio occupied by the fluoride particles 314 is 7% or more and 22% or less. Condition (1): The first region R1 is located on the plate magnet 311 side of the interface I between the plate magnet 311 and the insulating bonding layer 313. Condition (2): The first region R1 is a rectangle that is 10 μm in the stacking direction and 50 μm in the direction perpendicular to the stacking direction. Condition (3): When a line L2 is drawn that passes through the center of gravity G2 of the planar figure of the plate magnet 311 that appears in the cross section and extends in the stacking direction, the center CT1 of the rectangle is located on the line L2. Condition (4): The rectangle is in contact with the insulating bonding layer 313.

[0239] A method for identifying the first region R1 will be specifically described with reference to FIGS. 36 and 37 . The plate magnet 311 in FIG. 36 has an upper bottom surface 11A1, a lower bottom surface 11A2, and a side surface 11B. As shown in FIG. 37 , an insulating bonding layer 313 is located above the upper bottom surface 11A1. That is, the upper bottom surface 11A1 of the plate magnet 311 forms an interface I between the plate magnet 311 and the insulating bonding layer 313. The interface I between the plate magnet 311 and the insulating bonding layer 313 can be identified, for example, by image analysis using EPMA. As shown in FIG. 36 , the center of gravity G2 of the planar figure of the plate magnet 311 is identified. Because the planar figure of the plate magnet 311 is rectangular, the center of gravity G2 of the planar figure of the plate magnet 311 can be identified as the intersection of the diagonals of the planar figure. A straight line L2 is drawn that passes through the center of gravity G2 and extends in the Z-axis direction. Of the rectangles with a size of 10 μm in the Z-axis direction and 50 μm in the X-axis direction, whose center CT1 lies on the line L2, the rectangle whose top side is in contact with the insulating bonding layer 313 is identified as the first region R1. Note that the actual interface I has irregularities as shown in FIG. 35 , but the lowest point of the irregularities (the point closest to the center of the plate magnet) is used as the contact point, and a rectangle 10 μm in the stacking direction and 50 μm in the planar direction is identified as R1. Note that in the case where the lower bottom surface 11A2 of the plate magnet 311 forms the interface I between the plate magnet 311 and the insulating bonding layer 313, the rectangle whose bottom side is in contact with the insulating bonding layer 313 may be identified as the first region R1.

[0240] The area ratio occupied by the fluoride particles 314 is 7% or more, more preferably 10% or more, and even more preferably 12% or more, from the viewpoint of improving the insulation between the plate magnets 311. On the other hand, from the viewpoint of ensuring the bonding strength between the plate magnets 311, it is 22% or less, more preferably 21% or less. From these viewpoints, the area ratio occupied by the fluoride particles 314 is 7% or more and 22% or less, more preferably 10% or more and 22% or less, and even more preferably 12% or more and 21% or less. The area ratio occupied by the fluoride particles 314 can be calculated, for example, by performing micro X-ray analysis or XRD analysis on a cross section of the magnet stack 310, performing image analysis using EPMA within the first region R1, and then calculating the area ratio occupied by the fluoride particles 314 in the entire first region R1. The requirement regarding the area ratio occupied by the fluoride particles 314 of a metal of Group 2A of the periodic table may be satisfied by observing the first regions R1 of the plurality of plate magnets 311 and finding that the requirement is met in at least one of the regions.

[0241] The area ratio occupied by the fluoride particles 314 can be controlled, for example, by adjusting the hot-pressing conditions. For example, increasing the pressure during hot-pressing tends to increase the area ratio occupied by the fluoride particles 314. On the other hand, decreasing the pressure during hot-pressing tends to decrease the area ratio occupied by the fluoride particles 314. Furthermore, for example, increasing the temperature during hot-pressing tends to increase the area ratio occupied by the fluoride particles 314. On the other hand, decreasing the temperature during hot-pressing tends to decrease the area ratio occupied by the fluoride particles 314. Furthermore, increasing the pressure application time during hot-pressing tends to increase the area ratio occupied by the fluoride particles 314. On the other hand, decreasing the pressure application time during hot-pressing tends to decrease the area ratio occupied by the fluoride particles 314.

[0242] (6) Requirements for the Average Particle Diameter of Fluoride Particles 314 The average particle diameter of the fluoride particles 314 is not particularly limited. The average particle diameter of the fluoride particles 314 is preferably 2.0 μm or more and 8.0 μm or less, more preferably 2.2 μm or more and 6.0 μm or less, and even more preferably 2.5 μm or more and 4.0 μm or less. When the average particle diameter of the fluoride particles 314 is within the above range, the insulation resistance is increased and eddy current loss can be reduced. Furthermore, when the average particle diameter of the fluoride particles 314 is within the above range, the plate magnet 311 and the insulating bonding layer 313 are easily compatible with each other, and the adhesion strength between the plate magnet 311 and the insulating bonding layer 313 can be improved.

[0243] The average particle diameter of the fluoride particles 314 can be determined, for example, by subjecting a cross section of the magnet laminate 310 to micro X-ray analysis or XRD analysis, performing image analysis using an EPMA, and calculating the equivalent-area circle diameter from the particle area of ​​the fluoride particles 314. Specifically, the average particle diameter is determined as follows: Focus is placed on a plurality of fluoride particles 314 that can be observed without missing any particles within a predetermined observation field (e.g., 50 μm × 50 μm). The diameter (equivalent-area circle diameter) of an ideal circle (true circle) having an area equal to the area (projected area) of each particle image of the fluoride particles 314 is calculated as the particle diameter of each particle. The average particle diameter is then determined by arithmetically averaging the particle diameters of each particle.

[0244] The average particle size of fluoride particles 314 can be controlled by adjusting the average particle size of fluoride particles 314 of the metal of Group 2A of the periodic table used as the raw material of insulating bonding layer 313 .

[0245] (7) Requirements for the Second Region R2 It is preferable that the magnet stack 310 contains a heavy rare earth element in the second region R2, which satisfies the following conditions (5) and (6): Condition (5): The second region R2 is a rectangle measuring 10 μm in the stacking direction and 50 μm in the direction perpendicular to the stacking direction. Condition (6): The center CT2 of the rectangle is located at the center of gravity G2 of the planar shape of the plate magnet 311 that appears in the cross section.

[0246] A method for identifying the second region R2 will be described in detail with reference to Figure 36. As shown in Figure 36, the center of gravity G2 of the planar figure of the plate magnet 311 is identified. Because the planar figure of the plate magnet 311 is rectangular, the center of gravity G2 of the planar figure of the plate magnet 311 can be identified as the intersection of the diagonals of the planar figure. A rectangle measuring 10 μm in the Z-axis direction and 50 μm in the X-axis direction, with its center CT1 at the center of gravity G2, is identified as the second region R2.

[0247] The presence of the heavy rare earth element in the second region R2 can be confirmed, for example, by subjecting the cross section of the magnet laminate 310 to micro X-ray analysis or XRD analysis in combination with composition analysis by EPMA. The requirements for the second region R2 need only be met by observing the second regions R2 of the multiple plate magnets 311 when observing the cross-sectional structure of the magnet laminate 310 and finding that the requirements are met in at least one of the regions. To ensure that the heavy rare earth element is present in the second region R2, the magnet laminate 310 may be manufactured by, for example, hot pressing. A method for ensuring that the heavy rare earth element is present in the second region R2 by hot pressing will be described later.

[0248] (8) Requirements for the Ratio β / α of Heavy Rare Earth Elements When the amount of heavy rare earth elements in the first region R1 is α% by mass and the amount of heavy rare earth elements in the second region R2 is β% by mass, the magnet stack 310 preferably satisfies the following relationship: 0.70≧β / α≧0.50.

[0249] The amounts α and β of heavy rare earth elements can be calculated, for example, by subjecting a cross section of the magnet laminate 310 to micro X-ray analysis or XRD analysis in combination with EPMA composition analysis. For example, 10 or more points in each region are measured using EPMA point analysis, and the average value is used as the amount of heavy rare earth element in that region. The amount α of heavy rare earth element in the first region R1 is not particularly limited. The amount α of heavy rare earth element is preferably 1.0 mass% or more and 1.6 mass% or less. The amount β of heavy rare earth element in the second region R2 is not particularly limited. The amount β of heavy rare earth element is preferably more than 0.3 mass%, more preferably 0.7 mass% or more and 0.95 mass% or less. The requirement regarding the ratio β / α of heavy rare earth elements can be met by calculating the ratio β / α of heavy rare earth elements of multiple plate magnets 311 and finding that it is met in at least one of the plate magnets 311, and it is preferable that it be met in at least all five plate magnets 311 stacked in succession.

[0250] The ratio β / α of the heavy rare earth elements can be controlled by, for example, adjusting the thickness of the plate magnet 311 and the hot pressing conditions. For example, increasing the thickness of the plate magnet 311 tends to decrease the β / α value. On the other hand, decreasing the thickness of the plate magnet 311 tends to increase the β / α value. For example, increasing the temperature during hot pressing while shortening the pressure time tends to decrease the β / α value. On the other hand, decreasing the temperature during hot pressing while lengthening the pressure time tends to increase the β / α value.

[0251] (9) Requirements for the angle of the plate magnet 311 As shown in Figure 38, when three or more plate magnets 311 are used and the plate magnets 311 have an upper bottom surface 11A1, a lower bottom surface 11A2, and a side surface 11B, the plate magnets 311 are preferably arranged as follows: The upper bottom surface 11A1 and the lower bottom surface 11A2 of one plate magnet 311 are flat surfaces that extend approximately parallel to each other. In the following description of the magnet stack 310 in Figure 38, the topmost magnet 311 located at the top is designated by the symbol 3111, the bottommost magnet 311 located at the bottom is designated by the symbol 3113, and each intermediate magnet 311 excluding the topmost magnet 3111 and the bottommost magnet 3113 is designated by the symbol 3112. In the magnet stack 310, it is preferable that the angle formed between the lower bottom surface 11A2 of the top magnet 3111, which is located at the top of the plate magnets 311, and the lower bottom surface 11A2 of each intermediate magnet 3112 is 3° or less. The above angle is more preferably 2.5° or less, and even more preferably 2.2° or less. The angle formed between the lower bottom surface 11A2 of the top magnet 3111 and the lower bottom surface 11A2 of each intermediate magnet 3112 is 0° or more. An angle of 0° formed between the lower bottom surface 11A2 of the top magnet 3111 and the lower bottom surface 11A2 of the intermediate magnet 3112 indicates that the top magnet 3111 and the intermediate magnets 3112 are arranged approximately parallel to each other.

[0252] The angle formed between the lower bottom surface 11A2 of the top magnet 3111 and the lower bottom surface 11A2 of the intermediate magnets 3112 can be calculated by image analysis of the cross-sectional observation images of the magnet stack 310. For each of a plurality of cross-sectional observation images (for example, two cross-sectional observation images), the angle formed between the lower bottom surface 11A2 of the top magnet 3111 and the lower bottom surface 11A2 of each intermediate magnet 3112 is calculated, and if all angles are 3° or less, it is determined that the angle formed between the lower bottom surface 11A2 of the top magnet 3111 located at the top and the lower bottom surface 11A2 of each intermediate magnet 3112 is 3° or less.

[0253] The fact that the above angle is 3° or less is one indicator that the plate magnets 311 are arranged approximately parallel. With a configuration in which the above angle is 3° or less, the orientation direction of each plate magnet 311 can be aligned, improving the magnetic flux density of the magnet stack 310. The angle between the lower bottom surface 11A2 of the top magnet 3111 and the lower bottom surface 11A2 of each intermediate magnet 3112 can be reduced by, for example, performing a hot pressing process to make the thickness of the insulating bonding layer 313 between the plate magnets 311 uniform.

[0254] 2. Manufacturing Method of Magnet Laminate 310 There are no particular limitations on the manufacturing method of the magnet laminate 310. An example of a manufacturing method of the magnet laminate 310 in which plate magnets 311 and insulating bonding layers 313 are alternately stacked is shown below.

[0255] In the manufacturing method of the laminated magnet 310, the (1) SC alloy preparation step, (2) hydrogen crushing step, (3) coarse pulverization step, first lubricant addition step, (4) fine pulverization step, and second lubricant addition step are the same as the explanations of the (1) SC alloy preparation step, (2) hydrogen crushing step, (3) coarse pulverization step, first lubricant addition step, (4) fine pulverization step, and second lubricant addition step in "2. Manufacturing method of rare earth magnet 10" in the first embodiment, and this explanation applies as is.

[0256] (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 0.5 mm to 4.0 mm) can be obtained without a cutting process.

[0257] In the manufacturing method of the magnet laminate 310, the (6) mold disassembly step, the first firing step, the (7) insulating layer application step, the (8) laminate temporary fixing step, and the (9) hot pressing step are the same as the explanations of the (6) mold disassembly step, the first firing step, the (7) insulating layer application step, the (8) laminate temporary fixing step, and the (9) hot pressing step in "2. Manufacturing method of rare earth magnet 10" in the first embodiment, and this explanation applies as is.

[0258] The magnet stack 310 obtained as described above can be understood as a magnet stack manufactured by hot pressing (hot uniaxial pressing) a laminate having at least a pair of plate magnets 311, 311 (sintered SC alloys) sandwiching the raw material of the insulating bonding layer 313 between them so that pressure is applied in a direction that crushes the raw material of the insulating bonding layer 313. The magnet stack 310 can also be understood as a magnet stack manufactured by arranging a first plate magnet 311 (sintered SC alloy), the raw material of the insulating bonding layer 313, and a second plate magnet 311 (sintered SC alloy) in this order to form a laminate, and then applying pressure to the first plate magnet 311 and the second plate magnet 311 from both sides while heating the laminate. The raw material of the insulating bonding layer 313 may preferably contain inorganic crystals. The raw material of the insulating bonding layer 313 may further contain a component containing a heavy rare earth element. For example, the raw material of the insulating bonding layer 313 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 %.

[0259] 3. Uses of the Magnet Laminate 310 The uses of the magnet laminate 310 are not particularly limited. The magnet laminate 310 is suitable as a magnet for a motor. The magnet laminate 310 has low eddy current loss generated internally and is resistant to deterioration over time, 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 bonding layer 313 of the magnet laminate 310 is primarily composed of inorganic crystals, its insulating performance is less susceptible to changes due to the influence of humidity, temperature, and deterioration over time than insulating bonding layers made of resin or the like. Therefore, the magnet laminate 310 is useful for various applications where resistance to changes in insulating performance is desired. For details of the motor, please refer to the first embodiment, and a description thereof will be omitted.

[0260] 4. Actions and Effects of the Present Embodiment The magnet stack 310 of the present embodiment can reduce eddy current loss generated internally while ensuring the bonding strength of the multiple plate magnets 311. The reason for this is presumed to be as follows. Note that the present disclosure is not limited to this presumption. The magnet stack 310 of the present embodiment has the Nd-rich phase 17A and fluoride particles 314 of a metal of Group 2A of the periodic table between the plate magnets 311, thereby improving the insulation between the plate magnets 311 and reducing eddy current loss. Furthermore, if the area ratio of the fluoride particles 314 in the first region R1 is 7% or more and 22% or less, it is possible to ensure both the insulation between the plate magnets 311 and the bonding strength of the plate magnets 311.

[0261] When the average particle size of the fluoride particles 314 is 2.0 μm or more and 8.0 μm or less, the insulation resistance is increased and the eddy current loss can be suitably reduced.

[0262] When a heavy rare earth element is present in the second region R2, the coercive force can be improved.

[0263] When the above requirement (8) regarding the ratio β / α of heavy rare earth elements is satisfied, by allowing a high concentration of heavy rare earth elements to be present on the surface of plate magnet 311 while suppressing the concentration of heavy rare earth elements inside, it becomes possible to achieve excellent heat resistance while reducing the amount of expensive heavy rare earth elements used.

[0264] If the requirement (9) regarding the angle of the plate magnet 311 is satisfied, the strength of the joint surface of the plate magnet 311 against stress can be improved. If the plate magnets 311 are arranged so as not to be substantially parallel to each other and the angle is greater than 3°, the plate magnets 311 will be more likely to break under stress. [Example]

[0265] The present disclosure will be explained in more detail below with reference to examples.

[0266] 1. Fabrication of Laminated Magnets of Experimental Examples 1G to 21G, and Experimental Examples 1H to 7H (1) SC Alloy Preparation Process The main raw materials of Nd / Pr alloy, alloy containing Co, Al, Cu, Ga, Zr, and single metals were mixed to form strip cast alloys (SC alloys) (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.

[0267] (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.

[0268] (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.

[0269] (4) Fine pulverization step, second lubricant addition step The SC alloy powder after adding the lubricant was finely pulverized in a nitrogen atmosphere using a jet mill. The average particle size D50 after fine pulverization was 2.0 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.

[0270] (5) Powder Filling Step, Orientation Step, and Compaction 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 subsequent step. In the samples of Experimental Examples 1G to 21G and Experimental Examples 1H to 7H, each magnet had the thickness shown in Table 6 and was a rectangular parallelepiped with dimensions of 5 mm x 16 mm. 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 to 20 MPa, packing density: 3.0 g / cm. ３ -4.0 g / cm ３ , relative density: 40%-52%.

[0271] (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.

[0272] (7) Insulating Bonding Layer Coating Step After the first firing step, the partition plates were removed from the fired object, and the raw material for the insulating bonding layer was coated on six surfaces of the magnet before lamination. ２ and TbF ３ The compound powder and the solvent were mixed. ３ The proportion of the compound powder was 10 mass % to 20 mass %. The thickness of the raw material for the insulating bonding layer was 12 μm or more and 14 μm or less. The raw material for the insulating bonding layer was applied in the air by a spray method.

[0273] (8) Laminate Temporarily Fixing Process Eight to eighty magnets coated with an insulating bonding layer were stacked in air and temporarily fixed. The number of magnets 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.

[0274] (9) Hot Pressing Step The temporarily fixed laminate was placed in a hot press mold and subjected to uniaxial hot pressing. This step was carried out under a vacuum atmosphere (for example, 10 －３ Pa-10 －４ The hot pressing was carried out under a pressure of 700°C to 1100°C, or in an inert atmosphere (nitrogen atmosphere, argon atmosphere). The hot pressing temperature was 700°C to 1100°C, the hot pressing time was 10 minutes to 1 hour, the hot pressing pressure was 3 MPa to 100 MPa, and the hot pressing heat treatment time was 10 minutes to 20 hours. In this manner, laminated magnet samples were produced for Experimental Examples 1G to 21G and Experimental Examples 1H to 7H.

[0275] 2. Characteristics of Experimental Examples 1G to 21G and Experimental Examples 1H to 7H The plate magnets of Experimental Examples 1G to 21G and Experimental Examples 1H to 7H were analyzed by X-ray diffraction (XRD). ２ Fe １４ Since the peak intensity of B was the largest, the plate magnet was Nd ２ Fe １４ It was determined that the main phase was B.

[0276] Furthermore, the cross sections of the laminated magnets of Experimental Examples 1G to 21G and Experimental Examples 1H to 7H were subjected to micro X-ray analysis or XRD analysis, and confirmed in combination with EPMA composition analysis. This confirmed the presence of an Nd-rich phase and fluoride particles of a metal of Group 2A of the periodic table in the range from the interface I between the plate magnet and the insulating bonding layer to a depth of 10 μm on the plate magnet side.

[0277] Table 6 summarizes the properties of the plate magnets and insulating bonding layers for each of Experimental Examples 1G to 21G and Experimental Examples 1H to 7H. The "Thickness" column for "Plate Magnet" indicates the thickness (mm) of each plate magnet. The "Area Percentage" column for "Fluoride Particles" indicates the area percentage occupied by fluoride particles, measured using the method described above in "(5) Requirements for the Area Percentage Occupied by Fluoride Particles 314." The "Average Particle Diameter" column for "Fluoride Particles" indicates the particle diameter of the fluoride particles, measured using the method described above in "(6) Requirements for the Average Particle Diameter of Fluoride Particles 314."

[0278] The column "First region: α" in the "Amount of heavy rare earth element" indicates the amount of heavy rare earth element in the first region, measured by the method described above in "(8) Requirement regarding the ratio β / α of heavy rare earth element." The column "Second region: β" indicates the amount of heavy rare earth element in the second region, measured by the method described above in "(8) Requirement regarding the ratio β / α of heavy rare earth element." The column "Concentration ratio: β / α" indicates the value of β / α, calculated by the method described above in "(8) Requirement regarding the ratio β / α of heavy rare earth element."

[0279] The "Angle of Plate Magnet" column in the "Stacked Magnet" section shows the largest angle between the bottom surface of the top magnet and the bottom surface of each intermediate magnet, measured using the method described in the embodiment. If the angle listed in this "Angle of Plate Magnet" column is 3° or less, the above (9) requirement regarding the angle of the plate magnet 311 (requirement (g) described below) is met.

[0280]

[0281] 3. Performance Evaluation (1) Evaluation Method for Residual Magnetic Flux Density Residual magnetic flux density (T) was measured using a pulse BH tracer. The measurement evaluation direction was perpendicular to the surface of the top magnet for laminated magnets. A high residual magnetic flux density is an indicator of strong magnetic force.

[0282] The evaluation was made as follows: "A": 1.43T or more and less than 1.45T; "B": 1.40T or more and less than 1.43T; "C": Less than 1.40T.

[0283] (2) Evaluation method for coercive force Coercive force (kA / m) was measured using a pulsed BH tracer. The measurement direction was perpendicular to the surface of the top magnet for laminated magnets. A high coercive force is an indicator of high heat resistance as a magnet.

[0284] The evaluation was made as follows: "A": 2150 kA / m or more and less than 2400 kA / m; "B": 2000 kA / m or more and less than 2150 kA / m; "C": less than 2000 kA / m

[0285] (3) Evaluation of Heat Generation Temperature A 5mm x 16mm x 50mm block magnet was prepared as a reference. The block magnet and the laminated magnets of Experimental Examples 1G-21G and 1H-7H were attached to a motor, and tests were conducted by running the motor at rotation speeds of 2000 rpm, 4000 rpm, 6000 rpm, and 8000 rpm. Immediately after the test, the surface temperatures of the block magnet and the laminated magnets of Experimental Examples 1G-21G and 1H-7H were measured using a laser and Thermo Label (registered trademark). The surface temperature (°C) of each of the laminated magnets of Experimental Examples 1G-21G and 1H-7H was subtracted from the surface temperature (°C) of the block magnet to calculate a difference (°C), and the results were evaluated according to the following criteria. A lower difference (°C) is an indicator of an advantage in reducing eddy current loss.

[0286] The evaluation was made as follows: "A": difference value is less than -20°C; "B": difference value is between -20°C and -10°C; "C": difference value is -10°C or more.

[0287] (4) Evaluation of Durability Each of the laminated magnets of Experimental Examples 1G to 21G and Experimental Examples 1H to 7H was left standing for 100 hours under the following conditions. After that, the presence or absence of peeling between the plate magnet and the insulating bonding layer was visually checked. The absence of peeling even in a hotter and more humid environment is one indicator of the high durability of the laminated magnet. Condition 1: In the atmosphere, 60°C Condition 2: 50% relative humidity, 60°C Condition 3: 50% relative humidity, 70°C

[0288] The evaluation was made as follows: "A": Peeled off under condition 3 (relative humidity 50%, 70°C), and did not peel off under conditions 2 and 1. "B": Peeled off under condition 2 (relative humidity 50%, 60°C), and did not peel off under condition 1. "C": Peeled off under condition 1 (air, 60°C).

[0289] 4. Evaluation Results The evaluation results are shown in Table 6. Experimental Examples 1G to 21G satisfy the following requirements (a) to (d): Requirement (a): The laminated magnet is formed by alternately stacking plate magnets containing rare earth elements and insulating bonding layers. Requirement (b): The plate magnet is made of Nd ２ Fe １４ B is the main phase. Requirement (c): The thickness of the sheet magnet is 0.5 mm or more and 4.0 mm or less. Requirement (d): When an imaginary line passing through the center of gravity of the laminated magnet and extending in the stacking direction is taken, and a cross section of the laminated magnet is cut so that the cross-sectional area of ​​the laminated magnet is smallest on an imaginary plane containing the imaginary line, an Nd-rich phase with a higher Nd content than the main phase and fluoride particles of a metal from Group 2A of the Periodic Table are present in the range from interface I between the sheet magnet and the insulating bonding layer to a depth of 10 μm on the sheet magnet side, and the area ratio of the fluoride particles in the first region is 7% or more and 22% or less.

[0290] In contrast, Experimental Examples 1H to 7H do not satisfy the following requirements: Experimental Examples 2H, 5H, and 6H do not satisfy requirements (c) and (d); and Experimental Examples 1H, 3H, 4H, and 7H do not satisfy requirement (d).

[0291] Experimental Examples 1G to 21G were rated either "A" or "B" for heat generation temperature. Experimental Examples 1G to 21G were rated "A" or "B" for durability. In contrast, Experimental Examples 3H and 5H to 7H were rated "C" for heat generation temperature. Experimental Examples 1H to 7H were rated "C" for durability. It was suggested that Experimental Examples 1G to 21G can reduce eddy current loss generated internally and ensure the bonding strength of multiple plate magnets.

[0292] Furthermore, among Experimental Examples 1G to 21G, Experimental Examples 7G to 21G, which further satisfied the following requirement (e), were evaluated as "A" in terms of heat generation temperature. It was suggested that by satisfying requirement (e), eddy current loss can be further reduced. Requirement (e): The average particle size of the fluoride particles is 2.0 μm or more and 8.0 μm or less.

[0293] Furthermore, among Experimental Examples 1G to 21G, Experimental Examples 12G to 21G, which further satisfied the following requirement (f), were rated "A" for coercivity and "A" for durability. It was suggested that by satisfying requirement (f), it is possible to improve coercivity and ensure the bonding strength of multiple plate magnets. Requirement (f): When the amount of heavy rare earth element in the first region is α% by mass and the amount of heavy rare earth element in the second region is β% by mass, the following relationship is satisfied: 0.70≧β / α≧0.50.

[0294] Furthermore, among Experimental Examples 1G to 21G, Experimental Examples 17G to 21G, which further satisfied the following requirement (g), were rated "A" for residual magnetic flux density. It was suggested that satisfying requirement (g) can improve magnetic force. Requirement (g): Among the plate magnets, the angle formed between the bottom surface of the topmost magnet located at the top and the bottom surface of each intermediate magnet excluding the topmost magnet and the bottommost magnet located at the bottom is 3° or less.

[0295] 5. Effects of the Examples Experimental Examples 1G to 21G were able to reduce the eddy current loss generated inside, and also ensure the bonding strength of the multiple plate magnets.

[0296] 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.

[0297] (Additional Note in the Fourth Embodiment) This specification includes the following inventions: [1] A laminated magnet in which plate magnets containing rare earth elements and insulating bonding layers are alternately stacked, wherein the plate magnets are Nd ２ Fe １４A laminated magnet having B as a main phase, the thickness of the sheet magnet being 0.5 mm or more and 4.0 mm or less, when a cross section of the laminated magnet is observed on a virtual plane including a virtual line passing through the center of gravity of the laminated magnet and extending in the stacking direction, with the cross section being smallest, a Nd-rich phase having a higher Nd content than the main phase and fluoride particles of a metal of Group 2A of the Periodic Table are present in a range from the interface between the sheet magnet and the insulating bonding layer to a depth of 10 μm on the sheet magnet side, and the fluoride particles occupy an area of ​​7% or more and 22% or less in a first region that satisfies the following conditions (1) to (4): Condition (1): The first region is present on the sheet magnet side from the interface between the sheet magnet and the insulating bonding layer. Condition (2): The first region is a rectangle measuring 10 μm in the stacking direction and 50 μm in the direction perpendicular to the stacking direction. Condition (3): When a line is drawn that passes through the center of gravity of the planar figure of the plate magnet that appears in the cross section and extends in the stacking direction, the center of the rectangle is located on the line. Condition (4): The rectangle is in contact with the insulating bonding layer. [2] The laminated magnet according to [1], wherein the average particle size of the fluoride particles is 2.0 μm or more and 8.0 μm or less. [3] The laminated magnet according to [1] or [2], wherein a heavy rare earth element is present in the second region that satisfies the following conditions (5) to (6): Condition (5): The second region is a rectangle that is 10 μm in the stacking direction and 50 μm in the direction perpendicular to the stacking direction. Condition (6): The center of the rectangle is located at the center of gravity of the planar figure of the plate magnet that appears in the cross section. [4] The magnet laminate according to [3], wherein, where the amount of the heavy rare earth element in the first region is α% by mass and the amount of the heavy rare earth element in the second region is β% by mass, the following relationship is satisfied: 0.70≧β / α≧0.50. [5] The magnet laminate according to [1] or [2], wherein three or more plate magnets are used, each plate magnet has an upper bottom surface, a lower bottom surface, and a side surface, and the lower bottom surface of the uppermost magnet among the plate magnets forms an angle of 3° or less with the lower bottom surface of any of the intermediate magnets excluding the uppermost magnet and the lowermost magnet. [6] A motor having the magnet laminate according to [1] or [2].

[0298] <Explanation of symbols in the description of the first embodiment> 10... rare earth magnet 11... magnet 13... insulating layer 30... motor 31... stator 33... rotor 34... rotating shaft 35... rotating core 37... shaft hole 39... magnet hole <Explanation of symbols in the description of the second embodiment> 110... laminated magnet 111... magnet 113... insulating layer 130... motor 131... stator 133... rotor 134... rotating shaft 135... rotating core 137... shaft hole 139... magnet hole <Explanation of symbols in the description of the third embodiment> 210... laminated magnet 211... magnet 11A... main surface 11A1... upper bottom surface 11A2... lower bottom surface 11B... side surface 213... insulating layer 214... inorganic crystal particle 217... surface layer 17A... rare earth rich phase (Nd rich phase) 2111...Top magnet 2112...Intermediate magnet 2113...Bottom magnet <Explanation of symbols in the description of the fourth embodiment> 310...Laminated magnet 311...Plate magnet 11A1...Upper bottom surface 11A2...Lower bottom surface 11B...Side surface 313...Insulating bonding layer 314...Fluoride particles 317...Surface layer 17A...Nd-rich phase 3111...Top magnet 3112...Intermediate magnet 3113...Bottom magnet I...Interface

Claims

1. A laminated magnet comprising: a plurality of magnets; and insulating layers present between the plurality of magnets, the insulating layers being primarily composed of inorganic crystals.

2. The laminated magnet described in claim 1, wherein a plurality of the magnets and the insulating layers are stacked in a first direction, the magnets contain a rare earth element and have a curved shape that is convex in a second direction when viewed from the first direction, and the average orientation of each portion of a 1 mm width centered on the normal line at multiple points from one end to the other end on the curve on the convex side in the second direction on the outer periphery of the magnet when viewed from the first direction is 90% or more.

3. The laminated magnet according to claim 1, wherein the magnet includes a crystalline phase containing rare earth elements and iron 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 magnet has a surface layer of a rare earth-rich phase having a higher rare earth element content than the crystalline phase.

4. The laminated magnet according to claim 3, wherein a plurality of the magnets and the insulating layers are laminated in a first direction, 10 or more magnets are used per 50 mm of the dimension of the laminated magnet in the first direction, and the volume resistivity of the laminated magnet in the first direction is 100 Ω·cm or more and 2000 Ω·cm or less.

5. The magnet laminate according to claim 4, wherein the inorganic crystals have a main phase of a fluoride of Group 2A of the periodic table and a subphase of at least one type selected from the group consisting of oxides of rare earth elements and nitrides of rare earth elements.

6. A laminated magnet as described in any one of claims 3 to 5, wherein three or more magnets are used, the magnets being plate magnets having upper and lower bottom surfaces, and the angle between the lower bottom surface of the topmost magnet located at the top of the plate magnets and the lower bottom surfaces of each of the intermediate magnets excluding the topmost magnet and the bottommost magnet located at the bottom is 3° or less.

7. The magnet is a plate magnet containing a rare earth element, and the insulating layer is laminated alternately. The plate magnet is Nd ２ Fe １４ The laminated magnet according to claim 1, wherein B is a main phase, the thickness of the sheet magnet is 0.5 mm or more and 4.0 mm or less, and when a cross section of the laminated magnet is observed by taking a virtual line passing through the center of gravity of the laminated magnet and extending in the stacking direction, and cutting the laminated magnet so that the cross-sectional area is the smallest on a virtual plane including the virtual line, a Nd-rich phase having a higher Nd content than the main phase and fluoride particles of a metal of Group 2A of the Periodic Table are present in a range from the interface between the sheet magnet and the insulating layer to a depth of 10 μm on the sheet magnet side, and the fluoride particles occupy an area ratio of 7% to 22% in a first region that satisfies the following conditions (1) to (4). Condition (1): The first region is present on the sheet magnet side from the interface between the sheet magnet and the insulating layer. Condition (2): The first region is a rectangle of 10 μm in the stacking direction and 50 μm in a direction perpendicular to the stacking direction. Condition (3): When a straight line is drawn that passes through the center of gravity of the planar shape of the plate magnet that appears in the cross section and extends in the stacking direction, the center of the rectangle is on the straight line. Condition (4): The rectangle is in contact with the insulating layer.

8. The laminated magnet according to claim 7, wherein the average particle size of the fluoride particles is 2.0 μm or more and 8.0 μm or less.

9. The magnet laminate according to claim 7 or 8, wherein a heavy rare earth element is present in the second region that satisfies the following conditions (5) to (6): Condition (5): The second region is a rectangle that is 10 μm in the stacking direction and 50 μm in a direction perpendicular to the stacking direction. Condition (6): The center of the rectangle is located at the center of gravity of the planar figure of the plate magnet that appears in the cross section.

10. The magnet laminate according to claim 9, wherein, when the amount of said heavy rare earth element in said first region is α% by mass, and the amount of said heavy rare earth element in said second region is β% by mass, the relationship 0.70≧β / α≧0.50 is satisfied.

11. A laminated magnet as described in claim 7 or claim 8, wherein three or more plate magnets are used, each plate magnet having an upper bottom surface, a lower bottom surface, and a side surface, and the angle between the lower bottom surface of the topmost magnet located at the top among the plate magnets and the lower bottom surface of any of the intermediate magnets excluding the topmost magnet and the bottommost magnet located at the bottom is 3° or less.

12. A motor having the laminated magnet according to claim 3 or 7.

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