Rare earth magnets, multilayer magnets, and motors

Abstract

To provide rare earth magnets, laminated magnets, and motors with excellent magnetic performance. [Solution] A rare earth magnet containing rare earth elements, characterized in that it satisfies pre-set conditions for parameters affecting magnetic performance. The parameter is the particle size of the particles constituting the rare earth magnet, and the condition is that in the frequency distribution of the particle size, the frequency of particles with a particle size in the range of 2.5 μm or more and 3.5 μm or less is 85% or more. The parameter is the degree of orientation of the rare earth magnet, and the condition is that 80% or more of the rare earth magnet has a degree of orientation in the range of 96.2% or more and 97.2% or less.

Description

Technical Field

[0001] The present invention relates to rare earth magnets, laminated magnets, and motors.

Background Art

[0002] Rare earth magnets containing rare earth elements may be arranged on a rotor constituting a motor. As such a rare earth magnet, Patent Document 1 discloses a rare earth magnet provided with a resistance layer containing rare earth elements, iron, and oxygen on its surface. Further, Patent Document 2 discloses a rare earth magnet having a dividing layer formed to extend in a direction orthogonal to the orientation direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Each of the rare earth magnets disclosed in Patent Documents 1 and 2 aims to reduce eddy current loss by providing a resistance layer or a dividing layer. However, improvement in magnetic performance (distribution of coercive force, degree of orientation, distribution of residual magnetic flux density, etc.) of the rare earth magnet itself excluding such a configuration has still been desired.

[0005] The present invention has been made to solve at least part of the above problems, and an object thereof is to provide a rare earth magnet having excellent magnetic performance.

Means for Solving the Problems

[0006] The present invention has been made to solve at least part of the above problems and can be realized in the following forms.

[0007] (1) According to one embodiment of the present invention, a rare earth magnet is provided. This rare earth magnet satisfies predetermined conditions for parameters that affect its magnetic performance.

[0008] (2) In the rare earth magnet according to the above embodiment, the parameter is the particle size of the particles constituting the rare earth magnet, and the condition is that in the frequency distribution of the particle size, the frequency of particles having a particle size in the range of 2.5 μm or more and 3.5 μm or less is 85% or more. The smaller the variation in particle size of the particles constituting the rare-earth magnet, the more uniform the distribution of coercivity in the rare-earth magnet becomes. With this configuration, the frequency of particles with a particle size within the range of 2.5 μm or more and 3.5 μm or less is 85% or more, so the variation in particle size is relatively small, and thus it is possible to provide a rare-earth magnet with a uniform distribution of coercivity.

[0009] (3) In the rare earth magnet according to the above embodiment, the parameter is the degree of orientation of the rare earth magnet, and the condition may be that 80% or more of the rare earth magnet has a degree of orientation within the range of 96.2% or more and 97.2% or less. With this configuration, more than 80% of the magnet has an orientation degree within the range of 96.2% or higher and 97.2% or lower, thus providing a rare earth magnet in which the orientation degree is relatively high in most parts.

[0010] (4) In the rare earth magnet according to the above embodiment, the parameter is the area ratio of pores in the cross-section of the rare earth magnet, and the condition is that the porosity, which is the ratio of pores in the cross-section, is 1.0% or less, and in the cross-section, the proportion of the total area of ​​the pores, calculated from the circular value of the pores, that is less than or equal to the length obtained by multiplying the average particle size of the particles constituting the rare earth magnet by 0.35, is 80% or more. The lower the porosity of a rare-earth magnet, the more the variation in its magnetic performance is suppressed. Furthermore, the smaller the pore diameter of the pores contained in the rare-earth magnet, the more the variation in its magnetic performance is suppressed. With this configuration, it is possible to provide a rare-earth magnet with a porosity of 1.0% or less, where the pore diameter of most of the pores contained in the rare-earth magnet is relatively small, thus suppressing variations in magnetic performance.

[0011] (5) In the rare earth magnet according to the above embodiment, the area occupied by the liquid phase at the grain boundary triple point in a 200 μm × 200 μm field of view observed on the surface of the rare earth magnet may be 8% or less, and the atomic content of the rare earth element contained in the liquid phase may be 42% or more and 68% or less. The inventors of this invention have found that when the liquid phase at the grain boundary triple point occupies 8% or less of a 200 μm × 200 μm field of view observed on the surface of a rare earth magnet, and the atomic content of rare earth elements in that liquid phase is 42% or more and 68% or less, the variation in the distribution of coercivity is suppressed. Therefore, this configuration makes it possible to provide a rare earth magnet in which the variation in the distribution of coercivity is suppressed.

[0012] (6) According to another embodiment of the present invention, a laminated magnet is provided. This laminated magnet comprises any of the rare earth magnets described in (1) to (5) above and a plurality of insulating layers, wherein the rare earth magnets and the insulating layers are alternately laminated. Rare-earth magnets tend to have low eddy current losses. Furthermore, the insulating layer exhibits almost no change in resistance with temperature, thus reducing eddy current losses over a wide temperature range. Therefore, this configuration, with alternating layers of such rare-earth magnets and insulating layers, provides a laminated magnet capable of reducing eddy current losses in high-temperature environments.

[0013] (7) According to another embodiment of the present invention, a motor is provided, wherein one of the rare earth magnets described in (1) to (5) above is arranged in the rotor. According to this configuration, since a rare earth magnet with excellent magnetic performance is arranged on the rotor, a motor with excellent rotation efficiency can be provided.

[0014] In addition, the present invention can be realized in various aspects. For example, in addition to a rare earth magnet, a laminated magnet, and a motor in which these are arranged on the rotor, it can be realized in the form of a device or the like provided with any one of a rare earth magnet, a laminated magnet, and a motor.

Brief Description of the Drawings

[0015] [Figure 1] It is an explanatory diagram schematically showing the rare earth magnet of the first embodiment. [Figure 2] It is an explanatory diagram schematically showing a cross section of the rare earth magnet. [Figure 3] It is an explanatory diagram showing the results of an evaluation test of rare earth magnets with different various parameters. [Figure 4] It is an explanatory diagram schematically showing the laminated magnet of the second embodiment. [Figure 5] It is a cross-sectional view of the motor of the third embodiment.

Modes for Carrying Out the Invention

[0016] <First Embodiment> FIG. 1 is an explanatory diagram schematically showing a rare earth magnet 1 as the first embodiment of the present invention. In FIG. 1, XYZ axes orthogonal to each other are shown. The rectangular parallelepiped-shaped rare earth magnet 1 shown in FIG. 1 is defined by a side Sx along the X-axis direction, a side Sy along the Y-axis direction, and a side Sz along the Z-axis direction.

[0017] The rare earth magnet 1 contains rare earth elements. Examples of the 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, it is preferable to contain one or more of Nd, Pr, Dy, and Tb as the rare earth elements, and it is more preferable to contain Nd as the main component. Note that having Nd as the main component means that the content (mass%) of Nd is the highest among the rare earth elements. The rare earth magnet 1 may contain transition metal elements and boron in addition to the rare earth elements. Such a magnet is also referred to as an R-T-B-based magnet.

[0018] The rare earth magnet 1 satisfies preset conditions regarding parameters that affect magnetic performance. Specifically, the rare earth magnet 1 satisfies at least one or more of the following conditions (1) to (4). Condition (1): The parameter that affects magnetic performance is the particle size of the particles constituting the rare earth magnet 1. The preset condition is that in the frequency distribution of the particle size, the frequency of particles having a particle size within the range of 2.5 μm or more and 3.5 μm or less is 85% or more. Condition (2): The parameter that affects magnetic performance is the degree of orientation of the rare earth magnet 1. The preset condition is that in the rare earth magnet 1, the portion having an orientation degree within the range of 96.2% or more and 97.2% or less is 80% or more. Condition (3): The parameter that affects magnetic performance is the area ratio of pores in the cross-section of the rare earth magnet 1. The preset condition is that the porosity, which is the ratio of pores in the cross-section, is 1.0% or less, and in the cross-section, the ratio of the partial total area, which is the total area of the pores calculated from the circular conversion value of the pore diameter and is less than or equal to the length obtained by multiplying the average particle size of the particles constituting the rare earth magnet 1 by 0.35, to the total area of the pores is 80% or more. Condition (4): The parameters that affect magnetic performance are the area occupied by the liquid phase at the grain boundary triple point in a 200 μm × 200 μm field of view observed on the surface of the rare earth magnet 1, and the atomic content of rare earth elements contained in the liquid phase. The pre-set conditions are that the area occupied by the liquid phase at the grain boundary triple point in that field of view is 8% or less, and the atomic content of rare earth elements contained in that liquid phase is 42% or more and 68% or less. Here, the rare earth elements refer to the various elements mentioned above as rare earth elements contained in the rare earth magnet 1. Furthermore, atomic content refers to the total amount of these various elements contained.

[0019] Regarding condition (1), the particle size and frequency distribution of the particles constituting the rare earth magnet 1 are calculated from SEM images taken of the chemically etched surface of the rare earth magnet 1 using a scanning electron microscope (SEM). Specifically, an SEM image of a 200 μm × 200 μm area of ​​the surface of the chemically etched rare earth magnet 1 is binarized, and then the area of ​​each particle is calculated as a perfect circle (πr). 2 After approximating, the particle size of the particles constituting the rare earth magnet 1 is calculated by considering its diameter (2r) as the particle size of each particle. Condition (1) is determined by preparing five such SEM images and summing the particle sizes of the particles calculated from these five SEM images. Chemical etching of the surface of the rare earth magnet 1 is performed using Nital solution for 10 to 100 seconds.

[0020] Regarding condition (2), the degree of orientation of the rare earth magnet 1 is the 0.25 cm section cut from the rare earth magnet 1. 3 Of the rectangular prism-shaped samples, 0.125 cm 3The measurement will be performed using a pulsed high magnetic field measuring instrument (magnetic field: 4T) in the specified region. Depending on the size of the rare earth magnet 1 from which the rectangular parallelepiped samples are cut, as many samples as possible will be cut, with at least three samples to be cut and measured. In addition, the surface of the samples will be cut so that the surface of the rare earth magnet 1 is not included. Then, condition (2) will be determined based on whether the ratio of the number of samples with an orientation degree between 96.2% and 97.2% to the total number of measured samples is 80% or more. For example, if 10 samples are cut and measured, and 8 of those samples have an orientation degree between 96.2% and 97.2%, then the portion of the rare earth magnet 1 with an orientation degree between 96.2% and 97.2% is considered to be 80%, and condition (2) will be deemed to be satisfied.

[0021] Regarding condition (3), the porosity, pore diameter, total area (the sum of the areas of pores in that cross-section), and partial total area (the sum of the areas of pores in that cross-section with a pore diameter less than or equal to the length obtained by multiplying the average particle size of the particles constituting the rare earth magnet 1 by 0.35) are calculated from five SEM images of a 200 μm × 200 μm area of ​​the cross-section of the rare earth magnet 1. Note that the cross-section referred to here is a mechanically polished cross-section.

[0022] Figure 2 is a schematic diagram illustrating the cross-section CS of the rare earth magnet 1. Using Figure 2, we will explain how to calculate the porosity in the cross-section of the rare earth magnet 1. Six pores ST are formed in the cross-section CS in Figure 2. The porosity in condition (3), as explained using Figure 2, is the sum of the total area of ​​the six pores ST and the area of ​​the cross-section CS (hatched area), multiplied by 100 after dividing the sum of the total area of ​​the six pores ST, and expressed in units of %. For example, in the case of an SEM image taken over a 200 μm × 200 μm area, the value is obtained by multiplying the sum of the total area of ​​all pores contained in the SEM image by 200 μm × 200 μm and multiplying by 100 (%). The average value of the porosity calculated from each of the five SEM images is used to determine condition (3).

[0023] The pore diameter in the cross-section of the rare earth magnet 1 is determined by binarizing an SEM image of a 200 μm × 200 μm area of ​​the cross-section of the rare earth magnet 1, and then calculating the area of ​​each pore as a perfect circle (πr). 2 After approximating, the diameter (2r) is considered to be the pore diameter of each pore, thereby calculating the pore diameter in the cross-section of the rare earth magnet 1.

[0024] The total area of ​​the cross-section of the rare-earth magnet 1 is calculated by summing the areas of all pores captured in the SEM image. The partial total area of ​​the cross-section of the rare-earth magnet 1 is calculated by summing the areas of pores whose pore diameter (as described above), calculated from the circular equivalent value of the pores, is less than or equal to the length obtained by multiplying the average particle size of the particles constituting the rare-earth magnet 1 (the median diameter of the particle sizes of all particles captured in the SEM image) by 0.35. The partial total area for each of the five SEM images is calculated by referring to the average particle size calculated for each SEM image. To determine condition (3), the value obtained by dividing the partial total area by the total area for each of the five SEM images and multiplying the result by 100 is calculated, and the average of these five calculated values ​​is used.

[0025] Regarding condition (4), the region occupied by the liquid phase at the grain boundary triple point and the atomic content of rare earth elements contained in the liquid phase are calculated from five SEM images taken on the surface of the rare earth magnet 1, where the grain boundary triple point is included in a 200 μm × 200 μm area. The region occupied by the liquid phase at the grain boundary triple point is 200 μm × 200 μm, and the region occupied by the liquid phase at the grain boundary triple point (unit: μm) 2 This is the value obtained by dividing by ) and multiplying by 100, and is expressed in units of %. The atomic content of rare earth elements contained in the liquid phase is measured by SEM-EDX (energy-dispersive X-ray spectroscopy). For the determination of condition (4), the average value of the region occupied by the liquid phase at the grain boundary triple point, calculated from each of the five SEM images, and the average value of the atomic content of rare earth elements contained in the same liquid phase, calculated from each of the five SEM images, are used.

[0026] Figure 3 shows, in table form, the results of evaluation tests conducted on rare earth magnets (Examples 1-15 and Comparative Examples 1-5) with different parameters related to magnetic performance. Among the examples and comparative examples with different parameters, Examples 1-15 correspond to the first embodiment of the present invention, which is rare earth magnet 1.

[0027] Examples 1-15 and Comparative Examples 1-5 were prepared according to the following steps (1)-(6).

[0028] (Process 1) SC alloy preparation process A raw material alloy (strip-cast alloy (SC alloy)) containing rare earth elements, transition metal elements, and boron is prepared. Examples of transition metal elements include one or more selected from the group consisting of iron (Fe), cobalt (Co), and nickel (Ni).

[0029] (Step 2) Hydrogen decomposition process In a hydrogen atmosphere, hydrogen is absorbed into the SC alloy at a predetermined temperature and time, causing the grain boundaries (rare earth-rich phase) and the inside of the grains of the SC alloy to become brittle. The hydrogen decomposition process is carried out under conditions where the predetermined temperature is 150-200 degrees Celsius and the predetermined time is 1-3 hours.

[0030] (Step 3) Coarse grinding step, first lubricant addition step The SC alloy powder, which has undergone a hydrogenation process, is coarsely ground (coarse grinding process). At this time, it is preferable to add a lubricant to the SC alloy powder (first lubricant addition process). This process is preferably carried out under an inert atmosphere (such as a nitrogen atmosphere or an argon atmosphere).

[0031] (Step 4) Fine grinding step, second lubricant addition step The SC alloy powder after the coarse grinding process is finely ground to a predetermined average particle size D50 (fine grinding process). At this time, a lubricant may be added to the finely ground SC alloy powder to improve its fluidity (second lubricant addition process). This process is preferably carried out under an inert atmosphere (nitrogen atmosphere, argon atmosphere, etc.). In Examples 1 to 15, the fine grinding process is performed with a predetermined average particle size D50 of 2.0 μm to 3.5 μm. In Comparative Examples 1 to 5, the fine grinding process is performed with a predetermined average particle size D50 of 3.5 μm to 4.5 μm.

[0032] (Step 5) Powder filling process, orientation process, molding process The SC alloy powder, after the fine grinding process, is filled into a mold. This process is preferably carried out under an inert atmosphere (such as a nitrogen or argon atmosphere). The mold used has multiple molding spaces of a predetermined thickness. Each molding space is separated, for example, by multiple partition plates. After filling the mold with powder, a magnetic field is applied in a predetermined direction to align the orientation of the SC alloy powder. Then, the SC alloy powder filled in the mold is pressurized to form an SC alloy molded body. In this way, an SC alloy molded body having a predetermined degree of orientation (for example, an average degree of orientation of 90% or more) and a predetermined thickness (for example, a thickness of 1.2 mm to 2.5 mm) can be obtained without performing a cutting process.

[0033] (Step 6) Mold removal process, firing process The molded body is removed from the mold (mold removal process). The molded body is fired at a predetermined firing temperature for a predetermined time (firing process). This firing is preferably carried out in a vacuum. Prior to this firing, heating at a temperature lower than the firing temperature may be performed for dehydrogenation. The firing process is carried out under conditions where the predetermined firing temperature is 950 degrees and the predetermined time is 0.5 to 4.0 hours.

[0034] The particle size and frequency distribution of the particles constituting the rare earth magnet 1, which are related to condition (1), are influenced by the setting of the average particle size D50 in the fine grinding process, density unevenness during powder filling in the molding process, and heat treatment conditions (firing temperature and firing time) in the firing process.

[0035] The degree of orientation of the rare earth magnet 1 related to condition (2) is influenced by the particle size and frequency distribution of the particles constituting the rare earth magnet 1, as well as the applied conditions in the orientation process, the particle density in the molded body, and the shape of the molded body.

[0036] Regarding condition (3), the porosity in the cross-section of the rare earth magnet 1 is influenced not only by the particle size and frequency distribution of the particles constituting the rare earth magnet 1, but also by the particle density in the molded body and the heat treatment conditions (firing temperature and firing time) in the firing process.

[0037] The region occupied by the liquid phase at the grain boundary triple point and the atomic content of rare earth elements contained in the liquid phase, which relate to condition (4), are influenced by the composition of the raw material alloy prepared in the SC alloy preparation process, the heat treatment conditions (fire temperature and firing time) in the firing process, and the cooling rate.

[0038] Let's return to the explanation of Figure 3. In the "Magnet Shape" section of the table in Figure 3, "X," "Y," and "Z" represent the lengths of sides Sx, Sy, and Sz in Figure 1, respectively, and the unit is mm.

[0039] In the table in Figure 3, "Average particle size" under "Particle size" refers to the average particle size (median diameter) of the particles constituting the rare earth magnet 1, with the unit being μm. In the table in Figure 3, "Frequency" under "Particle size" refers to the frequency of particles among the particles constituting the rare earth magnet 1 whose particle size is within the range of 2.5 μm or more and 3.5 μm or less, with the unit being %. "Frequency" is an item that serves as the criterion for determining condition (1), and condition (1) is met when it is 85% or more. The "Frequency" is calculated using the method described above.

[0040] In the table in Figure 3, the "Number of Measurements" for "Orientation Degree" is the number of rectangular parallelepiped samples cut from the rare earth magnet 1 and measured for orientation degree, with the unit being "pieces". In the table in Figure 3, the "Percentage" for "Orientation Degree" is the percentage of the number of samples whose orientation degree was within the range of 96.2% or higher and 97.2% or lower, relative to the "Number of Measurements", with the unit being %. For example, in Example 1, the "Number of Measurements" was 3, and the number of samples whose orientation degree was within the range of 96.2% or higher and 97.2% or lower was 2, so 2 / 3 × 100 ≈ 67 (%). The "Percentage" is an item that serves as the criterion for determining condition (2), and condition (2) is met when it is 80% or higher.

[0041] In the table in Figure 3, "Porosity" under "Porosity" refers to the porosity of the cross-section of the rare earth magnet 1, and is expressed in units of %. In the table in Figure 3, "Occupancy Rate" under "Porosity" refers to the percentage of the total area of ​​the cross-section of the rare earth magnet 1 occupied by the partial total area (the area of ​​pores with a diameter less than or equal to the average particle size of the particles constituting the rare earth magnet 1 multiplied by 0.35) out of the total area (the total area of ​​pores in that cross-section), and is expressed in units of %. Both "Porosity" and "Occupancy Rate" are criteria for determining condition (3), and condition (3) is met when "Porosity" is 1.0% or less and "Occupancy Rate" is 80% or more. Note that "Porosity" and "Occupancy Rate" are calculated using the method described above.

[0042] In the table in Figure 3, the "occupied area" at the "triple point" is the area occupied by the liquid phase at the grain boundary triple point within a 200 μm × 200 μm field of view observed on the surface of the rare earth magnet 1, and is expressed in units of %. In the table in Figure 3, the "atomic content" at the "triple point" is the atomic content of rare earth elements contained in the liquid phase, and is expressed in units of %. The "occupied area" and "atomic content" are the criteria for determining condition (4), and condition (4) is met when the "occupied area" is 8% or less and the "atomic content" is 42% or more and 68% or less. The "occupied area" and "atomic content" are calculated using the method described above.

[0043] In the table in Figure 3, "Rectangularity" in the "Evaluation Results" column represents the degree to which the demagnetization curve of rare earth magnet 1 is rectangular. "Rectangularity" was evaluated as "C" if it was 90% or less, "B" if it was greater than 90% but 93% or less, and "A" if it was greater than 93%.

[0044] In the table in Figure 3, the "Coercivity Distribution" in the "Evaluation Results" column represents the distribution of coercivity in rare-earth magnet 1. The "Coercivity Distribution" was evaluated as follows: "D" if the variation was 5% or more, "C" if the variation was 3% or more but less than 5%, "B" if the variation was 2.5% or more but less than 3%, and "A" if the variation was less than 2.4%.

[0045] In the table in Figure 3, the "Br distribution" in the "Evaluation Results" column represents the distribution of remanent magnetic flux density in rare earth magnet 1. Similar to the "Coercivity Distribution" mentioned above, the "Br distribution" was evaluated as follows: "D" if the variation was 5% or more, "C" if the variation was 3% or more but less than 5%, "B" if the variation was 2.5% or more but less than 3%, and "A" if the variation was less than 2.4%. The "Angularity," "Coercivity Distribution," and "Br Distribution" in the "Evaluation Results" were all measured using a vibrating sample magnetometer (VSM) or a pulsed BH tracer.

[0046] Comparative Examples 1-5 all failed to meet conditions (1)-(4). In all of Comparative Examples 1-5, the "squareness" was "C", the "coercivity distribution" was "D", and the "Br distribution" was "D".

[0047] Examples 1 to 5 all met only condition (1). In all of Examples 1 to 5, the "squareness" was "B", the "coercivity distribution" was "C", and the "Br distribution" was "C". In other words, compared to Comparative Examples 1 to 5, Examples 1 to 5 showed improved evaluations in all aspects of the "evaluation results": "squareness", "coercivity distribution", and "Br distribution".

[0048] Examples 6-9 all satisfied conditions (1) and (2). In all of Examples 6-9, the "squareness" was "B", the "coercivity distribution" was "C", and the "Br distribution" was "B". In other words, compared to Examples 1-5, Examples 6-9 had equivalent evaluations for "squareness" and "coercivity distribution" among the "evaluation results", but the evaluation of "Br distribution" was improved.

[0049] Examples 10 to 12 all satisfied conditions (1) to (3). In all of Examples 10 to 12, the "squareness" was "B", the "coercivity distribution" was "C", and the "Br distribution" was "A". In other words, compared to Examples 6 to 9, Examples 10 to 12 had equivalent evaluations for "squareness" and "coercivity distribution" among the "evaluation results", but the evaluation of "Br distribution" was improved.

[0050] Examples 13-15 all satisfied conditions (1)-(4). In all of Examples 13-15, "Rectangularity" was "A", "Coercivity Distribution" was "B", and "Br Distribution" was "A". In other words, compared to Examples 10-12, Examples 13-15 had the same evaluation of "Br Distribution" among the "Evaluation Results", but the evaluations of "Rectangularity" and "Coercivity Distribution" were improved. The "Evaluation Results" of Examples 1-15 and Comparative Examples 1-5 showed that the more conditions (1)-(4) that were satisfied, the better the "Evaluation Results".

[0051] The rare earth magnet 1 of the embodiment described above satisfies at least one of the above-mentioned conditions (1) to (4).

[0052] The smaller the variation in particle size of the particles constituting the rare-earth magnet 1, the more uniform the distribution of coercivity in the rare-earth magnet becomes. In other words, when the rare-earth magnet 1 satisfies condition (1), the variation in particle size of the particles constituting the rare-earth magnet 1 is relatively small, making it possible to provide a rare-earth magnet 1 with a uniform distribution of coercivity. Furthermore, a comparison of Examples 1-5 and Comparative Examples 1-5 in Figure 3 confirms that when condition (1) is met, not only the "coercivity distribution" but also the "squareness" and "Br distribution" are improved.

[0053] When the rare earth magnet 1 satisfies condition (2), it is possible to provide a rare earth magnet 1 in which the degree of orientation is relatively high in most parts. Furthermore, a comparison of Examples 6-9 and Examples 1-5 in Figure 3 shows that when condition (2) is satisfied in addition to condition (1), the "Br distribution" is further improved.

[0054] The lower the porosity of the rare earth magnet 1, the more the variation in magnetic performance of the rare earth magnet 1 is suppressed. Also, the smaller the pore diameter of the pores contained in the rare earth magnet 1, the more the variation in magnetic performance of the rare earth magnet 1 is suppressed. In other words, when the rare earth magnet 1 satisfies condition (3), the porosity is 1.0% or less, and the pore diameter of most of the pores contained in the rare earth magnet is relatively small, so it is possible to provide a rare earth magnet 1 with suppressed variation in magnetic performance. Furthermore, a comparison of Examples 10-12 and Examples 6-9 in Figure 3 shows that when condition (3) is satisfied in addition to conditions (1) and (2), the "Br distribution" is further improved.

[0055] The inventors of this application have found that when the liquid phase at the grain boundary triple point occupies 8% or less of a 200 μm × 200 μm field of view observed on the surface of the rare earth magnet 1, and the atomic content of rare earth elements in that liquid phase is 42% or more and 68% or less, the variation in the distribution of coercivity is suppressed. In other words, when the rare earth magnet 1 satisfies condition (4), it is possible to provide a rare earth magnet 1 in which the variation in the distribution of coercivity is suppressed. Furthermore, a comparison of Examples 13-15 and Examples 10-12 in Figure 3 shows that when condition (4) is satisfied in addition to conditions (1)-(3), not only the "coercivity distribution" but also the "angular shape" is improved.

[0056] <Second Embodiment> Figure 4 is a schematic diagram illustrating a laminated magnet 2 as a second embodiment of the present invention. The laminated magnet 2 comprises a plurality of rare earth magnets 1 and a plurality of insulating layers IN. As shown in Figure 4, in the laminated magnet 2, the rare earth magnets 1 and the insulating layers IN are stacked alternately. The rare earth magnets 1 referred to here are the same as the rare earth magnets 1 described in the first embodiment. In Figure 4, the orientation direction of the rare earth magnets 1 is the +X axis direction.

[0057] The insulating layer IN is mainly composed of inorganic crystals. Preferably, the inorganic crystals are non-magnetic crystalline particles. "Mainly composed of inorganic crystals" means that the inorganic crystal content in the insulating layer IN is 50% by mass or more. The composition of the insulating layer IN can be analyzed by the following method: The presence of inorganic crystals is determined by micro-X-ray analysis or XRD analysis, and the inorganic crystal content is calculated by combining this with compositional analysis using EPMA (Electron Probe Micro Analyser).

[0058] From the viewpoint of reducing eddy current loss, the insulating layer IN preferably contains one or more inorganic crystals selected from the group consisting of CaF2, BaF2, SrF2, MgF2, Al2O3, ZrO2, Dy2O3, Tb2O3, Nd2O3, TbF3, DyF3, LiF, SiO2, BN, ZrB2, Si3N4, TiB2, Pr2O3, and SiC.

[0059] The insulating layer IN is made of inorganic crystals, specifically fluorides from Group 2A of the periodic table, from the viewpoint of reducing eddy current losses. It is preferable that the insulating layer IN contains at least one of the following as a Group 2A fluoride of the periodic table: CaF2, BaF2, SrF2, and MgF2. Among these, it is particularly preferable that the insulating layer IN contains CaF2.

[0060] In Figure 4, each of the insulating layers IN is arranged to align with the XZ plane and the orientation direction of the rare earth magnet 1 (the +X axis direction in Figure 4). When a laminated magnet 2, which is formed by laminating the rare earth magnet 1 and the insulating layer IN as shown in Figure 4, is used as a motor magnet or the like, the insulating layer IN is arranged substantially parallel to the direction in which the magnetic flux generated in the stator passes through the rare earth magnet 1 (the X axis direction in Figure 4), thus effectively reducing eddy current losses. Note that each of the insulating layers IN may be arranged to align with the YZ plane or the XY plane with respect to the orientation direction of the rare earth magnet 1 (the +X axis direction in Figure 4).

[0061] Rare earth magnets 1 tend to have low eddy current losses. Furthermore, the insulating layer IN, which is mainly composed of inorganic crystals, shows almost no change in resistance from room temperature to 150°C, thus reducing eddy current losses over a wide temperature range. Therefore, a laminated magnet 2 in which such rare earth magnets 1 and insulating layer IN are alternately stacked is a laminated magnet 2 that can reduce eddy current losses generated internally in high-temperature environments.

[0062] <Third Embodiment> Figure 5 is a cross-sectional view of a motor 3 as a third embodiment of the present invention. The motor 3 comprises a stator 31 and a rotor 33 arranged inside the stator 31. A laminated magnet 2 is arranged on the rotor 33, and a winding (not shown) is arranged on the stator 31. The laminated magnet 2 referred to here is the same as the laminated magnet 2 described in the second embodiment. That is, the rare earth magnet 1 described in the first embodiment is arranged on the rotor 33. The motor 3 is an inner rotor type with the magnet arranged on the inside (rotating shaft side) and the winding arranged on the outside. The motor 3 is not limited to an inner rotor type. For example, the motor 3 may be an outer rotor type with the winding arranged on the inside (rotating shaft side) and the magnet arranged on the outside.

[0063] The rotor 33 comprises a rotating shaft 34, a rotating core 35, and multiple laminated magnets 2. 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. Multiple magnet holes 39 are formed in the rotating core 35 at intervals in the circumferential direction. A laminated magnet 2 is inserted into each magnet hole 39. Therefore, the motor 3 shown in Figure 5 is a motor with excellent rotational efficiency because the laminated magnets 2 with excellent magnetic performance are arranged in the rotor 33.

[0064] <Modified form of this embodiment> The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit, for example, the following modifications are also possible.

[0065] In the first embodiment described above, the examples shown in Table 3 of Figure 3 were Examples 1-5 that satisfied only condition (1), Examples 6-9 that satisfied conditions (1) and (2), Examples 10-12 that satisfied conditions (1)-(3), and Examples 13-15 that satisfied conditions (1)-(4), but are not limited to these. Embodiments of the present invention do not need to satisfy condition (1). More specifically, embodiments of the present invention only need to satisfy at least one of conditions (1)-(4).

[0066] In the second embodiment described above, the insulating layer IN was mainly composed of inorganic crystals, but is not limited to this. The insulating layer IN may be mainly composed of any material as long as it has insulating properties.

[0067] The embodiments of this specification have been described above based on the embodiments and modifications described above. The embodiments described above are for the purpose of facilitating understanding of this specification and do not limit it. This specification may be modified and improved without departing from its spirit and the scope of the claims, and equivalents thereof are included in this specification. Furthermore, any technical features that are not described as essential in this specification may be deleted as appropriate.

[0068] The present invention can also be realized in the following forms. [Application Example 1] A rare earth magnet containing rare earth elements, A rare earth magnet characterized by satisfying pre-set conditions for parameters that affect its magnetic performance. [Application Example 2] The rare earth magnet described in Application Example 1, The aforementioned parameter is the particle size of the particles constituting the rare earth magnet, The above condition is characterized in that, in the frequency distribution of particle size, the frequency of particles with a particle size within the range of 2.5 μm or more and 3.5 μm or less is 85% or more, for a rare earth magnet. [Application Example 3] A rare earth magnet as described in Application Example 1 or Application Example 2, The parameter is the degree of orientation of the rare earth magnet. The above condition is characterized in that 80% or more of the rare earth magnet has an orientation degree within the range of 96.2% or more and 97.2% or less. [Application Example 4] A rare earth magnet as described in any of Application Examples 1 to 3, The parameter is the area ratio of pores in the cross-section of the rare earth magnet. The above conditions are characterized in that the porosity, which is the proportion of pores in the cross-section, is 1.0% or less, and in the cross-section, the proportion of the total area of ​​pores in which the pore diameter calculated from the circular value of the pores is less than or equal to the length obtained by multiplying the average particle size of the particles constituting the rare earth magnet by 0.35 is 80% or more of the total area of ​​the pores. [Application Example 5] A rare earth magnet as described in any of Application Examples 1 to 4, The aforementioned parameters are the region occupied by the liquid phase at the grain boundary triple point in a 200 μm × 200 μm field of view observed on the surface of the rare earth magnet, and the atomic content of the rare earth element contained in the liquid phase. The aforementioned conditions are characterized in that the region is 8% or less, and the atomic content is 42% or more and 68% or less, for a rare earth magnet. [Application Example 6] It is a stacked magnet, Multiple rare earth magnets as described in any of Application Examples 1 to 5, It comprises multiple insulating layers, A laminated magnet characterized in that the rare earth magnet and the insulating layer are stacked alternately. [Application Example 7] It is a motor, A motor characterized in that a rare earth magnet described in any of Application Examples 1 to 5 is arranged in the rotor. [Explanation of Symbols]

[0069] 1…Rare earth magnets 2…Stacked magnets 3…motor 31…Stata 33...Rota 34…Rotation axis 35…Rotating iron core 37…Axial hole 39…Magnetic hole

Claims

1. A rare earth magnet containing rare earth elements, A rare earth magnet characterized by satisfying pre-set conditions for parameters that affect its magnetic performance.

2. A rare earth magnet according to claim 1, The aforementioned parameter is the particle size of the particles constituting the rare earth magnet, The above condition is characterized in that, in the frequency distribution of particle size, the frequency of particles with a particle size within the range of 2.5 μm or more and 3.5 μm or less is 85% or more, for a rare earth magnet.

3. A rare earth magnet according to claim 1, The parameter is the degree of orientation of the rare earth magnet. The aforementioned condition is a rare earth magnet characterized in that 80% or more of the rare earth magnet has an orientation degree within the range of 96.2% or more and 97.2% or less.

4. A rare earth magnet according to claim 1, The parameter is the area ratio of pores in the cross-section of the rare earth magnet. The above conditions are characterized in that the porosity, which is the proportion of pores in the cross-section, is 1.0% or less, and in the cross-section, the proportion of the total area of ​​the pores in which the pore diameter, calculated from the circular value of the pores, is less than or equal to the length obtained by multiplying the average particle size of the particles constituting the rare earth magnet by 0.35 is 80% or more of the total area of ​​the pores.

5. A rare earth magnet according to claim 1, The aforementioned parameters are the region occupied by the liquid phase at the grain boundary triple point in a 200 μm × 200 μm field of view observed on the surface of the rare earth magnet, and the atomic content of the rare earth element contained in the liquid phase. The aforementioned conditions are characterized in that the region is 8% or less, and the atomic content is 42% or more and 68% or less, for a rare earth magnet.

6. It is a stacked magnet, A plurality of rare earth magnets according to any one of claims 1 to 5, It comprises multiple insulating layers, A laminated magnet characterized in that the rare earth magnet and the insulating layer are stacked alternately.

7. It is a motor, A motor characterized in that a rare earth magnet according to any one of claims 1 to 5 is arranged in the rotor.

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