JP7391730B2 - Magnetic materials, permanent magnets, rotating electric machines, and vehicles - Google Patents

Description

Embodiments relate to magnetic materials, permanent magnets, rotating electric machines, and vehicles.

Permanent magnets are used in products in a wide range of fields, including rotating electric machines such as motors and generators, electrical equipment such as speakers and measuring instruments, and vehicles such as automobiles and railway cars. In recent years, there has been a demand for the above-mentioned products to be smaller and more efficient, and high-performance permanent magnets with high magnetization and high coercive force are required.

Examples of high-performance permanent magnets include rare earth magnets such as Sm--Co magnets and Nd--Fe--B magnets. In these magnets, Fe and Co contribute to an increase in saturation magnetization. Furthermore, these magnets contain rare earth elements such as Nd and Sm, and exhibit large magnetic anisotropy due to the behavior of 4f electrons of the rare earth elements in the crystal field. Thereby, a large coercive force can be obtained.

Patent No. 4320701 JP2004-263232A Japanese Patent Application Publication No. 9-74006

The problem to be solved by the present invention is to increase the coercive force of the magnetic material.

The magnet material of the embodiment has a composition formula 1: R _x Nb _y B _t M _100-xy-t (R is at least one element selected from the group consisting of rare earth elements, and M is selected from Fe and Co. at least one element selected from the group, x is a number that satisfies 6.5x≦8 atomic%, y is a number that satisfies 0.75≦x/(x+y)≦0.95, t is a number satisfying 0≦t<12 atomic %), and comprises a main phase having at least one crystal phase selected from the group consisting of a TnMn _12- type crystal phase and a TbCu ₇ -type crystal phase, z defined by z=(100-xy-t)/(x+y) is a number satisfying 7.5≦z≦12. The magnet material has an intrinsic coercive force of 610 kA/m or more and a residual magnetization of 0.84 T or more, or the intrinsic coercive force of 660 kA/m or more and the residual magnetization of 0.82 T or more. .

It is a figure showing an example of a permanent magnet motor. FIG. 3 is a diagram showing an example of a variable magnetic flux motor. It is a figure showing an example of a generator. FIG. 1 is a schematic diagram showing an example of the configuration of a railway vehicle. FIG. 1 is a schematic diagram showing an example of the configuration of an automobile.

Embodiments will be described below with reference to the drawings. Note that the drawings are schematic, and for example, the relationship between thickness and planar dimension, the ratio of thickness of each layer, etc. may differ from the actual drawing. Furthermore, in the embodiments, substantially the same components are given the same reference numerals and explanations are omitted.

(First embodiment)
The magnet material of the embodiment contains a rare earth element, an M element (M is at least one element selected from the group consisting of Fe and Co), an Nb element, and a B element. The magnet material has a metal structure whose main phase is a crystalline phase containing a high concentration of M element. Saturation magnetization can be improved by increasing the M element concentration in the main phase. The main phase is the phase with the highest volume occupancy among the crystalline and amorphous phases in the magnet material. The magnetic material may include a subphase. The subphases are, for example, grain boundary phases, fine crystal phases, impurity phases, etc. that exist between the crystal grains of the main phase. Examples of the crystal phase containing a high concentration of M element include a ThMn ₁₂ -type crystal phase and a TbCu ₇ -type crystal phase.

By adding Nb element and B element in addition to the rare earth element and M element, the ability to form an amorphous state can be enhanced and the coercive force can be increased. One of the applications of the above-mentioned magnetic material is a bonded magnet and a motor using the same. In recent years, there has been an increasing demand for smaller and faster motors, and along with this, there has been an increasing demand for improved heat resistance of magnets. In order to improve heat resistance, it is necessary to improve coercive force.

One of the effective methods for developing a coercive force in a magnet material having large magnetic anisotropy is to refine the crystal grains in the magnet material. Therefore, it is preferable that the main phase has microcrystals. Microcrystals are formed by, for example, producing an amorphous ribbon using a liquid quenching method and then subjecting it to appropriate heat treatment to precipitate and grow crystal grains.

By refining the main phase with high magnetic anisotropy, individual crystal grains tend to be in a single domain state, suppressing the generation of reverse magnetic domains and domain wall propagation, and exhibiting high coercive force. If the crystal grain size is too fine or too coarse, the coercive force will be low, so the average crystal grain size of the main phase is preferably 0.1 nm or more and 100 nm or less, more preferably 0.5 nm or more and 80 nm or less. The thickness is more preferably 1 nm or more and 60 nm or less, and even more preferably 3 nm or more and 50 nm or less. Furthermore, the squareness ratio can be improved by narrowing the particle size distribution of the main phase.

A nonmagnetic or weakly magnetic grain boundary phase may be formed as the grain boundary phase. This breaks the magnetic coupling between crystal grains, increases the effect of suppressing the generation of reverse magnetic domains and the propagation of domain walls, and improves the coercive force.

In order to increase the coercive force, it is necessary to control the amounts of rare earth elements, M elements, Nb elements, and B elements added. The magnet material of the embodiment is represented by, for example, composition formula 1: R _x Nb _y B _t M _100-xy-t . Note that the magnet material may contain unavoidable impurities.

The R element is a rare earth element, and is an element that can bring large magnetic anisotropy to the magnet material and provide a high coercive force to the permanent magnet. Specifically, R elements include yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pr), samarium (Sm), europium (Eu), and gadolinium ( At least one element selected from the group consisting of Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). In particular, it is preferable to use Sm. For example, when a plurality of elements including Sm are used as the R element, the performance of the magnetic material, such as coercive force, can be improved by setting the Sm concentration to 50 atomic % or more of all the elements that can be used as the R element.

The amount x of the R element added preferably satisfies, for example, 6.2<x≦8 atomic %. If x is too small or too large, foreign phases will precipitate and the coercive force will decrease. The amount x of the R element to be added is a number that satisfies 6.3≦x≦7.7 atomic%, furthermore, a number that satisfies 6.4≦x≦7.5 atomic%, and furthermore, 6.5≦x≦ More preferably, the number satisfies 7.4 atomic %.

Niobium (Nb) is an element effective in stabilizing a crystal phase containing a high concentration of M element. It is also an effective element for promoting amorphization. By adjusting the addition amount y of the Nb element and the addition amount x of the R element so as to satisfy a specific relational expression, it is possible to improve the performance of the magnet material, for example, the coercive force. The amount y of the Nb element added is preferably a number satisfying, for example, 0.75≦x/(x+y)≦0.95.

When x/(x+y) is less than 0.75, the Sm concentration in the crystal structure decreases, the magnetic anisotropy of the magnet material decreases, and the stability of the main phase decreases, such as α-Fe phase. It becomes difficult to obtain a high coercive force for reasons such as easy decomposition into R ₂ Fe ₁₄ B phase.

When x/(x+y) is larger than 0.95, the amount of Nb becomes too small, making it difficult to make it amorphous, and the coercive force decreases. More preferably, it is a number that satisfies 0.76≦x/(x+y)≦0.93, and still more preferably a number that satisfies 0.77≦x/(x+y)≦0.9.

50 atomic % or less of the Nb element may be substituted with at least one element selected from the group consisting of zirconium (Zr), tantalum (Ta), and hafnium (Hf). Zr element, Ta element, and Hf element are effective elements for stabilizing the crystal phase and making it amorphous.

The M element is at least one element selected from the group consisting of Fe and Co, and is an element responsible for high saturation magnetization of the magnet material. Since Fe has higher magnetization than Fe and Co, it is preferable that 50 atomic % or more of the M element is Fe. By adding Co to the M element, the Curie temperature of the magnet material increases, and a decrease in saturation magnetization in a high temperature region can be suppressed. Furthermore, by adding a small amount of Co, the saturation magnetization can be increased more than when Fe alone is used. On the other hand, increasing the Co ratio leads to a decrease in the anisotropic magnetic field. Furthermore, if the Co ratio is too high, it also causes a decrease in saturation magnetization. Therefore, by appropriately controlling the ratio of Fe and Co, high saturation magnetization, high anisotropic magnetic field, and high Curie temperature can be simultaneously achieved. When M in compositional formula 1 is expressed as (Fe _1-y Co _y ), the preferable value of y is 0.01≦y<0.7, more preferably 0.01≦y<0.5, More preferably, 0.01≦y≦0.3. 20 atomic% or less of M elements are aluminum (Al), silicon (Si), chromium (Cr), manganese (Mn), nickel (Ni), vanadium (V), titanium (Ti), copper (Cu), and tantalum. (Ta) may be substituted with at least one element selected from the group consisting of tungsten (W), molybdenum (Mo), and gallium (Ga). The above elements contribute, for example, to the growth of crystal grains constituting the main phase.

Boron (B) is an element effective in promoting amorphization. By appropriately controlling the amount t of element B added, an amorphous ribbon can be obtained by a method with high industrial productivity such as a single roll quenching method. The amount t of the B element added is preferably a number that satisfies, for example, 0≦t<12 atomic %. If there is too much B element, different phases such as the R ₂ Fe ₁₄ B phase are likely to be formed, resulting in a decrease in coercive force. Although it is possible to make the material amorphous without substantially containing element B, when a single roll method is used, it is necessary to increase the peripheral speed of the roll to increase the cooling rate, which reduces industrial productivity. The amount t of element B added is more preferably a number that satisfies 0.5≦t≦11 atomic %, still more preferably a number that satisfies 1≦t≦10.8 atomic %, and even more preferably 2 The number satisfies ≦t≦10.5 atomic %.

A part of the R element may be replaced by a Y element. At this time, the magnetic material is represented by, for example, composition formula 2: (R _1-u Y _u ) _x Nb _y B _t M _100-xy-t . Note that the magnet material may contain unavoidable impurities. Regarding the explanation of the R element, the Nb element, the B element, and the M element, the above explanation can be used as appropriate.

The Y element is an effective element for stabilizing a crystal phase containing a high concentration of M element, such as a ThMn ₁₂ -type crystal phase or a TbCu ₇ -type crystal phase. The higher the M element concentration, the higher the saturation magnetization of the crystal phase containing a high concentration of M element, which can improve the magnetic properties. However, when the M element concentration increases, the crystal structure becomes unstable, leading to decomposition of the main phase , coercive force decreases due to precipitation of α-Fe or α-(Fe, Co) phase. On the other hand, by substituting a part of the R element with the Y element, the stability of the crystal phase containing a high concentration of the M element can be improved, and the M element concentration can be further increased. This makes it possible to achieve both high coercive force and high magnetization. It is preferable that the amount u of Y element added satisfies 0.01≦u≦0.5 atomic %. If u is too small, the stabilizing effect will be small, and if u is too large, the magnetic anisotropy will decrease and the coercive force will decrease. More preferably, u is a number satisfying 0.02≦u≦0.4 atomic %, and even more preferably 0.05≦u≦0.3 atomic %.

In addition, in the magnetic material represented by compositional formula 1 or compositional formula 2, the value of z defined by (100-xy-t)/(x+y) is proportional to the amount of M element added, and the value of z is The larger the value, the higher the magnetization obtained. It is preferable that z is a number satisfying 7.5≦z≦12. When z is less than 7.5, the M element concentration becomes low and the magnetization decreases. When z is larger than 12, precipitation of α-Fe or α-(Fe, Co) phase is unavoidable, resulting in a decrease in coercive force. It is more preferable that z is a number satisfying 8≦z≦12, still more preferably 8.5≦z≦12, still more preferably a number satisfying 9<z≦12, even more preferably 9 .5≦z≦12. In the case of the magnetic material represented by compositional formula 2, preferably the number satisfies 9<z≦12, and more preferably the number satisfies 9.5≦z≦12. By substituting a part of R with Y, the stability of the crystal phase containing a high concentration of the M element is improved, and it becomes easier to increase the coercive force in a composition with a large value of z.

In the magnet material represented by compositional formula 2, the amount x of the R element and the element Y, and the amount y of the Nb added are numbers that satisfy 4≦x≦11 atomic% and 0≦y≦6.5 atomic%, respectively. It is preferable that y be a number satisfying 0.75≦x/(x+y)≦0.95. More preferably, it is a number that satisfies 0.76≦x/(x+y)≦0.93, and still more preferably a number that satisfies 0.77≦x/(x+y)≦0.9. Further, x is more preferably a number satisfying 6.2<x≦8 atomic %, still more preferably a number satisfying 6.3≦x≦7.7 atomic %, still more preferably 6. The number satisfies 4≦x≦7.5 atomic %, and more preferably the number satisfies 6.5≦x≦7.4 atomic %.

The magnet material of the embodiment may further contain element A. Element A is at least one element selected from the group consisting of nitrogen (N), carbon (C), hydrogen (H), and phosphorus (P). The A element has the function of penetrating into the crystal lattice and causing at least one of, for example, expanding the crystal lattice and changing the electronic structure. Thereby, the Curie temperature, magnetic anisotropy, and saturation magnetization can be changed. Element A does not necessarily need to be added except as an unavoidable impurity.

The magnet material of the embodiment may be in the form of a quenched alloy ribbon produced by a liquid quenching method (melt span method), or may be in the form of a powder, for example, using a quenched alloy ribbon as a raw material. . The ribbon preferably has an average thickness of 10 μm or more and 60 μm or less. If the ribbon is too thin, the proportion of the surface deterioration layer increases and the magnetic properties, for example magnetization, decrease. Furthermore, if the ribbon is too thick, the cooling rate tends to be distributed within the ribbon, resulting in a decrease in coercive force. The average thickness of the ribbon is preferably 15 μm or more and 50 μm or less, more preferably 20 μm or more and 40 μm or less.

The magnetic material of the embodiment has an intrinsic coercive force of 300 kA/m or more and 2500 kA/m or less. In order to improve heat resistance, it is more preferably 500 kA/m or more and 2500 kA/m or less, still more preferably 600 kA/m or more and 2500 kA/m or less, still more preferably 610 kA/m or more and 2500 kA/m or less, and Preferably it is 620 kA/m or more and 2500 kA/m or less, more preferably 640 kA/m or more and 2500 kA/m or less.

The residual magnetization of the magnet material of the embodiment is 0.7T or more and 1.6T or less. The higher the residual magnetization, the more effective it is for downsizing the motor. The residual magnetization is preferably 0.75T or more and 1.6T or less, more preferably more than 0.8T and 1.6T or less.

The composition of the magnet material can be determined by, for example, high-frequency inductively coupled plasma-atomic emission spectroscopy (ICP-AES), scanning electron microscopy-energy dispersive X-ray spectroscopy (Scanning Electron Mic) roscope-Energy Dispersive X- ray Spectroscopy: SEM-EDX), Transmission Electron Microscope-Energy Dispersive X-ray Spectroscopy (TEM-EDX), scanning type Transmission electron microscopy - energy dispersive X-ray spectroscopy ( Scanning Transmission Electron Microscope-Energy Dispersive X-ray Spectroscopy (STEM-EDX) or the like. The volume ratio of each phase is determined comprehensively using observation using an electron microscope or optical microscope, X-ray diffraction, or the like.

The average particle size of the main phase is determined as follows. An arbitrary grain is selected from among the main phase crystal grains identified using STEM-EDX in the cross section of the magnet material, and the longest straight line A whose both ends touch another phase is drawn for the selected grain. Next, at the midpoint of this straight line A, draw a straight line B that is perpendicular to the straight line A and has both ends touching another phase. The average length of straight line A and straight line B is defined as phase diameter D. Obtain D of one or more arbitrary phases using the above procedure. The above D is calculated in five fields of view for one sample, and the average of each D is defined as the phase diameter (D). As the cross-section of the magnetic material, a cross-section of the sample at substantially the center of the surface having the maximum area is used.

The average thickness of the rapidly solidified alloy ribbon is determined, for example, as follows. The thickness of a thin strip of 10 mm or more is measured using a micrometer. The average thickness of the ribbon is calculated by measuring the thickness of 10 or more ribbon pieces and calculating the average value of the values excluding the maximum and minimum values.

Magnet properties such as coercive force and magnetization of the magnet material are calculated using, for example, a vibrating sample magnetometer (VSM).

Next, an example of a method for manufacturing the magnet material of the embodiment will be described. First, an alloy containing predetermined elements necessary for a magnet material is manufactured. For example, the alloy can be manufactured using an arc melting method, a high frequency melting method, a mold casting method, a mechanical alloying method, a mechanical grinding method, a gas atomization method, a reduction diffusion method, or the like.

The above alloy is melted and rapidly cooled. This makes the alloy amorphous. The melted alloy is cooled using, for example, a liquid quenching method (melt span method). In the liquid quenching method, molten alloy is injected onto rolls rotating at high speed. The roll may be a single roll type or a twin roll type, and the material used is mainly copper or the like. The cooling rate of the molten metal can be controlled by controlling the amount of molten metal to be injected and the circumferential speed of the rotating rolls. The degree of amorphization of the alloy can be controlled by composition and cooling rate. Moreover, if an amorphous alloy has already been obtained by using a gas atomization method or the like during the production of the above-mentioned alloy, there is no need to perform the rapid cooling step again.

Heat treatment is performed on the amorphous alloy or alloy ribbon. Thereby, the main phase can be crystallized and a metal structure including the main phase having microcrystals can be formed. For example, heating is performed at a temperature of 500° C. or more and 1000° C. or less for 5 minutes or more and 300 hours or less in an inert atmosphere such as Ar or vacuum.

If the temperature is too low, crystallization and uniformity will be insufficient and the coercive force will decrease. Furthermore, if the temperature is too high, a different phase is generated due to decomposition of the main phase, etc., and the coercive force and squareness are reduced. The heating temperature is, for example, more preferably 520°C or more and 800°C or less, still more preferably 540°C or more and 700°C or less, and still more preferably 550°C or more and 650°C or less. If the heating time is too short, crystallization and uniformity will be insufficient and the coercive force will decrease.

If the heating time is too long, a different phase is generated due to decomposition of the main phase, etc., and the coercive force and squareness deteriorate. Preferable heating time is 15 minutes or more and 150 hours or less, more preferably 30 minutes or more and 120 hours or less, still more preferably 1 hour or more and 120 hours or less, still more preferably 2 hours or more and 100 hours or less, and Preferably it is 3 hours or more and 80 hours or less.

After heating, the crystallized alloy or ribbon is cooled by a method such as furnace cooling, underwater quenching, gas quenching, or oil quenching.

Element A may be introduced into the above alloy. It is preferable that the alloy is ground into powder before the step of introducing the A element into the alloy. When the A element is nitrogen, by heating the alloy at a temperature of 200°C or more and 700°C or less for 1 hour or more and 100 hours or less in an atmosphere of nitrogen gas, ammonia gas, etc. at about 0.1 atmosphere or more and 100 atmospheres or less, The alloy can be nitrided to allow the N element to enter the alloy. When element A is carbon, the temperature is 300°C or more and 900°C or less in an atmosphere of C ₂ H ₂ , CH ₄ , C ₃ H ₈ , CO gas, or thermal decomposition gas of methanol at about 0.1 atm or more and 100 atm or less. By heating the alloy in a temperature range of 1 hour or more and 100 hours or less, the alloy can be carbonized and the C element can penetrate into the alloy. When element A is hydrogen, the alloy is hydrogenated by heating it at a temperature range of 200 to 700°C for 1 to 100 hours in an atmosphere of hydrogen gas or ammonia gas at about 0.1 to 100 atmospheres. , H elements can be introduced into the alloy. When the A element is phosphorus, the alloy can be phosphorized and the P element can be penetrated into the alloy.

A magnet material is manufactured through the above steps. Moreover, magnet powder is manufactured by pulverizing the above alloy or ribbon. Furthermore, a permanent magnet is manufactured using the above magnet material and magnet powder. An example of the magnet manufacturing process is shown.

A permanent magnet having a sintered body can be formed by pressurizing and sintering the magnet material. Pressure sintering methods include applying pressure with a press molding machine and then heating and sintering, using a discharge plasma sintering method, using a hot press, and using a hot working method. is applicable. For example, the magnetic material is pulverized using a pulverizer such as a jet mill or a ball mill, and a molded body is obtained by magnetically oriented pressing in a magnetic field of about 1 to 2 T at a pressure of about 1 ton. A sintered body is produced by heating and sintering the obtained molded body in an inert gas atmosphere such as Ar or vacuum. A permanent magnet can be manufactured by appropriately heat-treating the sintered body in an inert atmosphere or the like.

Further, a bonded magnet can be manufactured by pulverizing the above magnet material, fixing the pulverized material with a binder, and mixing the pulverized materials. As the binder, for example, thermosetting resin, thermoplastic resin, low melting point alloy, rubber material, etc. can be used. As a molding method, for example, a compression molding method or an injection molding method can be used.

The magnetic properties of a bonded magnet, particularly the residual magnetization and the maximum magnetic energy product, can be enhanced by increasing the density of the bonded magnet. Further, by increasing the density and reducing the voids in the bonded magnet, corrosion resistance can be improved.

The densified bonded magnet may have, for example, a magnetic material represented by compositional formula 3: R _x Nb _y B _t M _100-xy-t . R is at least one element selected from the group consisting of rare earth elements, M is at least one element selected from the group consisting of Fe and Co, and x satisfies 4.0<x≦11.0 atomic%. y is a number that satisfies 0≦y≦6.5, and t is a number that satisfies 0≦t<12 atomic %. For other explanations of the magnet material, the above explanation of the magnet material can be used as appropriate.

With magnet materials having a ribbon shape, it is difficult to increase the density due to factors such as friction between the materials during molding and springback of the material itself.

In order to increase the density of bonded magnets, in the compression molding process, there is a pressurization step in which a press pressure of 6×10 ² MPa or more is applied, and then the press pressure is increased to a pressure of 90% or less of the press pressure in the pressurization step. It is effective to alternate between lowering the pressure and depressurization step. By switching between pressurization and depressurization, the flow of the binder and material progresses in a direction that homogenizes the internal stress while releasing local residual stress due to springback and plastic deformation of the material. High density can be achieved by reducing voids. The density of the bonded magnet is, for example, 6.45 g/cm ³ or more and 7.8 g/cm ³ or less. The density of the bonded magnet is more preferably 6.53 g/cm ³ .

The pressure in the pressurizing step is preferably 6.0×10 ² MPa or more and 3.0×10 ³ MPa or less. If the pressure is less than 6.0×10 ² MPa, the effect of reducing voids is low because the force to flow the material and binder is insufficient. In the case of a pressure exceeding 3.0×10 ³ MPa, the pressurizing force is too strong, requiring special molds and equipment, and reducing productivity. The pressure in the pressurizing step is more preferably 8.0 x 10 ² MPa or more and 2.5 x 10 ³ MPa or less, and even more preferably 10.0 x 10 ² MPa or more and 2.0 x 10 ³ MPa or less. It is.

In the depressurization step, it is preferable to release the pressure to atmospheric pressure, but industrially, by allowing a pressure higher than atmospheric pressure to remain, lead time can be shortened and productivity can be improved. The pressure in the depressurization step is preferably 90% or less of the pressure in the pressurization step. If the pressure exceeds 90% of the pressure in the pressurizing step, the residual stress will not be sufficiently released in the depressurizing step, making it difficult for the material and binder to flow. The pressure in the depressurizing step is more preferably 60% or less of the pressure in the pressurizing step, and even more preferably 30% or less of the pressure in the pressurizing step. The lower limit of the pressure in the depressurization step is atmospheric pressure, and if it is less than atmospheric pressure, that is, in a reduced pressure state, a separate pressure reducing device is required, which significantly reduces productivity.

It is preferable to repeat the switching between the pressurizing step and the depressurizing step two or more times. If it is applied once, there will be little flow after the residual stress is released, and the effect of reducing voids will be low. The number of times of switching is more preferably 3 times or more, still more preferably 5 times or more, and even more preferably 10 times or more. The upper limit of the number of times of switching is preferably 20 times or less, for example. If it exceeds 20 times, there are too few remaining voids, so the material and binder do not flow, and the densification effect is low.

The average length of the magnet material used in the bonded magnet is preferably 5 μm or more and 1 mm or less. If the thickness is less than 5 μm, it is difficult for the material and binder to flow due to pressurization and depressurization, making it difficult to improve the density. If it exceeds 1 mm, the surface roughness of the bonded magnet will increase, reducing dimensional accuracy. The lower limit of the average length is, for example, more preferably 20 μm or more, further preferably 50 μm or more, even more preferably 100 μm or more, still more preferably 150 μm or more, and even more preferably 200 μm or more. The upper limit of the average length is, for example, more preferably 800 μm or less, and even more preferably 500 μm or less. By appropriately controlling the average length, it is possible to enhance the effect of increasing the density by repeating the pressurization step and the depressurization step, and it is possible to realize a bonded magnet having a high density of, for example, 6.53 g/cm ³ or more.

The density of the bonded magnet is determined from the dimensions and weight of the molded body. In order to further improve the dimensional accuracy, the bonded magnet may be subjected to a grinding process or the like before measurement. The average length of the magnetic material can be controlled, for example by sieving. The average length may be controlled by adjusting the grinding conditions such as the grinding time and screen diameter of various grinding devices such as cutter mills and hammer mills. The average length can be defined, for example, by determining the lengths of 50 or more powders in the long side direction from a SEM image and using the average value.

During compression molding, press pressure may be applied by applying rotational motion or reciprocating motion to a molding die such as a punch or a mortar. This adds forces such as shearing force, making it possible to achieve high density.

The binder of the bonded magnet includes resins such as epoxy resins, nylon resins, polyamide resins, polyimide resins, and silicone resins. The resin may be a powdered resin, a liquid resin, or a mixture of resins in these shapes, but it is particularly easy to increase the density of the bonded magnet when a liquid resin is used. The viscosity of the liquid resin is preferably 1 poise or more and 500 poise or less.

The binder content is preferably 0.5% by mass or more and 5% by mass or less. If it exceeds 5% by mass, the magnetic properties will be significantly degraded. If it is less than 0.5% by mass, the binding force will be insufficient and sufficient strength will not be obtained. The binder content is preferably 1% by mass or more and 4% by mass or less, more preferably 2% by mass or more and 3% by mass or less.

The bonded magnet may include a coupling material such as a titanium-based coupling material or a silicon-based coupling material. The coupling agent has the effect of improving the dispersibility of the powder and is effective in improving the magnet density. The density of magnet materials can be improved by surface treatment with a lubricant such as fatty acids, fatty acid salts, amines, and amine acids.

(Second embodiment)
A permanent magnet including the magnetic material of the first embodiment can be used in various motors and generators. It can also be used as a fixed magnet or variable magnet for a variable magnetic flux motor or variable magnetic flux generator. By using the permanent magnet of the first embodiment, various motors and generators are constructed. When the permanent magnet of the first embodiment is applied to a variable magnetic flux motor, the configuration and drive system of the variable magnetic flux motor may include techniques disclosed in, for example, JP-A No. 2008-29148 and JP-A No. 2008-43172. can be applied.

Next, a motor and a generator equipped with the above permanent magnet will be explained with reference to the drawings. FIG. 1 is a diagram showing a permanent magnet motor. In the permanent magnet motor 11 shown in FIG. 1, a rotor (rotor) 13 is disposed within a stator (stator) 12. A permanent magnet 15, which is the permanent magnet of the first embodiment, is arranged in the iron core 14 of the rotor 13. By using the permanent magnets of the first embodiment, it is possible to achieve higher efficiency, smaller size, lower cost, etc. of the permanent magnet motor 11 based on the characteristics of each permanent magnet. The permanent magnet can also be inserted into a flux barrier portion of a synchronous reluctance motor. Thereby, the power factor of the synchronous reluctance motor can be increased.

FIG. 2 is a diagram showing a variable magnetic flux motor. In the variable magnetic flux motor 21 shown in FIG. 2, a rotor 23 is disposed within a stator 22. In the iron core 24 of the rotor 23, the permanent magnets of the first embodiment are arranged as fixed magnets 25 and variable magnets 26. The magnetic flux density (magnetic flux amount) of the variable magnet 26 can be varied. Since the magnetization direction of the variable magnet 26 is orthogonal to the Q-axis direction, it is not affected by the Q-axis current and can be magnetized by the D-axis current. The rotor 23 is provided with magnetization windings (not shown). By passing current from the magnetization circuit through this magnetization winding, the magnetic field directly acts on the variable magnet 26.

According to the permanent magnet of the first embodiment, a suitable coercive force can be obtained for the fixed magnet 25. When the permanent magnet of the first embodiment is applied to the variable magnet 26, the coercive force may be controlled, for example, within a range of 100 kA/m or more and 500 kA/m or less by changing the manufacturing conditions. In addition, in the variable magnetic flux motor 21 shown in FIG. 2, the permanent magnet of the first embodiment can be used for both the fixed magnet 25 and the variable magnet 26, but the permanent magnet of the first embodiment can be used for either one of the magnets. Permanent magnets may also be used. The variable magnetic flux motor 21 can output large torque with a small device size, and is therefore suitable for motors such as hybrid cars and electric cars that require high output and small size motors.

Figure 3 shows the generator. The generator 31 shown in FIG. 3 includes a stator 32 using the above permanent magnet. A rotor 33 disposed inside the stator 32 is connected to a turbine 34 provided at one end of the generator 31 via a shaft 35. The turbine 34 is rotated by, for example, fluid supplied from the outside. Note that instead of using the turbine 34 that rotates using fluid, it is also possible to rotate the shaft 35 by transmitting dynamic rotation such as regenerative energy of an automobile. Various known configurations can be adopted for the stator 32 and rotor 33.

The shaft 35 is in contact with a commutator (not shown) disposed on the opposite side of the rotor 33 from the turbine 34, and the electromotive force generated by the rotation of the rotor 33 is used as the output of the generator 31 to generate a phase-separated bus bar. The power is then boosted to the grid voltage and transmitted via a main transformer (not shown). The generator 31 may be either a regular generator or a variable magnetic flux generator. Note that the rotor 33 is charged with static electricity from the turbine 34 and the shaft current accompanying power generation. For this reason, the generator 31 is equipped with a brush 36 for discharging the electrical charge on the rotor 33.

As described above, by applying the permanent magnet to a generator, effects such as higher efficiency, smaller size, and lower cost can be obtained.

The rotating electric machine may be mounted, for example, on a railway vehicle (an example of a vehicle) used for railway transportation. FIG. 4 is a diagram illustrating an example of a railway vehicle 100 that includes a rotating electric machine 101. As the rotating electric machine 101, the motor shown in FIGS. 1 and 2, the generator shown in FIG. 3, etc. can be used. When the above-mentioned rotating electrical machine is mounted as the rotating electrical machine 101, the rotating electrical machine 101 generates driving force by using, for example, electric power supplied from an overhead wire or electric power supplied from a secondary battery mounted on the railway vehicle 100. It may be used as an electric motor (motor) that outputs , or it may be used as a generator that converts kinetic energy into electric power and supplies electric power to various loads in the railway vehicle 100 . By using a highly efficient rotating electrical machine like the rotating electrical machine of the embodiment, it is possible to run a railway vehicle while saving energy.

The rotating electric machine may be installed in a vehicle (another example of a vehicle) such as a hybrid vehicle or an electric vehicle. FIG. 5 is a diagram illustrating an example of a vehicle 200 that includes a rotating electrical machine 201. As the rotating electric machine 201, the motor shown in FIGS. 1 and 2, the generator shown in FIG. 3, etc. can be used. When the above-described rotating electrical machine is installed as the rotating electrical machine 201, the rotating electrical machine 201 may be used as an electric motor that outputs the driving force of the automobile 200, or a generator that converts kinetic energy when the automobile 200 is running into electric power. . Further, the rotating electric machine may be installed in, for example, industrial equipment (industrial motor), air conditioning equipment (air conditioner/water heater compressor motor), wind power generator, or elevator (hoisting machine).

(Example 1-4)
Appropriate amounts of raw materials were weighed and an alloy was produced using an arc melting method. Next, the alloy was melted, and the resulting molten metal was quenched by a single roll method to produce a quenched alloy ribbon. The alloy ribbon was heated in an Ar atmosphere at a temperature of 650° C. for 4 hours, and then rapidly cooled with gas. The composition of the magnet material was evaluated using ICP-AES. In addition, the coercive force of the permanent magnet was evaluated using VSM. Table 1 shows the evaluation results of the composition, coercive force, and residual magnetization of the magnet material.

(Example 5-9)
Appropriate amounts of raw materials were weighed and an alloy was produced using an arc melting method. Next, the alloy was melted, and the resulting molten metal was quenched by a single roll method to produce a quenched alloy ribbon. The alloy ribbon was heated at a temperature of 630° C. for 12 hours in an Ar atmosphere, and then rapidly cooled with gas. The composition of the magnet material was evaluated using ICP-AES. Further, the coercive force and residual magnetization of the permanent magnet were evaluated using VSM. Table 1 shows the evaluation results of the composition, coercive force, and residual magnetization of the magnet material.

(Example 10-16)
Appropriate amounts of raw materials were weighed and an alloy was produced using an arc melting method. Next, the alloy was melted, and the resulting molten metal was quenched by a single roll method to produce a quenched alloy ribbon. The alloy ribbon was heated at a temperature of 600° C. for 30 hours in an Ar atmosphere, and then rapidly cooled with gas. The composition of the magnet material was evaluated using ICP-AES. Further, the coercive force and residual magnetization of the permanent magnet were evaluated using VSM. Table 1 shows the evaluation results of the composition, coercive force, and residual magnetization of the magnet material.

(Comparative example 1-3)
Appropriate amounts of raw materials were weighed and an alloy was produced using an arc melting method. Next, the alloy was melted, and the resulting molten metal was quenched by a single roll method to produce a quenched alloy ribbon. The alloy ribbon was heated at a temperature of 640° C. for 1 hour in an Ar atmosphere, and then rapidly cooled with gas. The composition of the magnet material was evaluated using ICP-AES. Further, the coercive force and residual magnetization of the permanent magnet were evaluated using VSM. Table 1 shows the evaluation results of the composition, coercive force, and residual magnetization of the magnet material. Table 1 shows the evaluation results of the composition, coercive force, and residual magnetization of the magnet material.

As shown in Table 1, the magnet material of Example 1-16 is represented by composition formula 1 or composition formula 2, and z defined by z=(100-xy-t)/(x+y) is 7. .5≦z≦12. Further, the magnet material of Example 1-16 has a main phase having at least one crystal phase selected from the group consisting of a TnMn _12- type crystal phase and a TbCu ₇ -type crystal phase. Further, the magnetic material of Example 1-16 has an intrinsic coercive force of 610 kA/m or more and a residual magnetization of more than 0.80 T.

(Example 17-19)
After producing a magnet material in the same manner as in Example 10-16, the magnet material was pulverized to have an average length of 200 μm or more and 500 μm or less. The pulverized powder, epoxy resin, and titanium coupling agent were weighed to be 97.0% by mass, 2.5% by mass, and 0.5% by mass, respectively, and an appropriate amount of acetone was added and mixed. Thereafter, the acetone was evaporated to prepare a mixed powder. After filling the mold with the obtained mixed powder, a pressure step of applying a pressure of 10.0 × 10 ² MPa to pressurize the filling material, and a depressurization step of depressurizing the filling to atmospheric pressure were alternately carried out. The process was changed and repeated five times to produce a molded body. The obtained molded body was heat-treated at a temperature of 130° C. for 1 hour to produce a bonded magnet, and its density and magnetic properties were evaluated. Table 2 shows the evaluation results of the composition of the magnet material, the density of the bonded magnet, the residual magnetization, and the maximum magnetic energy product. Remanent magnetization and maximum magnetic energy product were measured using a BH tracer.

(Example 20, 21)
A magnet material was produced in the same manner as in Example 10-16, and the magnet material was pulverized so that the average length was 100 μm or more and 200 μm or less. The pulverized powder, epoxy resin, and titanium coupling agent were weighed to be 97.0% by mass, 2.5% by mass, and 0.5% by mass, respectively, and an appropriate amount of acetone was added and mixed. Thereafter, the acetone was evaporated to prepare a mixed powder. After filling the mold with the obtained mixed powder, a pressure step of applying a pressure of 10.0 × 10 ² MPa to pressurize the filling material, and a depressurization step of depressurizing the filling to atmospheric pressure were alternately carried out. The process was changed and repeated five times to produce a molded body. The obtained molded body was heat-treated at a temperature of 130° C. for 1 hour to produce a bonded magnet, and its density and magnetic properties were evaluated. Table 2 shows the evaluation results of the composition of the magnet material, the density of the bonded magnet, the residual magnetization, and the maximum magnetic energy product. Remanent magnetization and maximum magnetic energy product were measured using a BH tracer.

(Comparative example 4)
A magnet material was produced in the same manner as in Example 10-16, and the magnet material was pulverized so that the average length was 200 μm or more and 500 μm or less. The pulverized powder, epoxy resin, and titanium coupling agent were weighed to be 97.0% by mass, 2.5% by mass, and 0.5% by mass, respectively, and an appropriate amount of acetone was added and mixed. Thereafter, the acetone was evaporated to prepare a mixed powder. After filling the mold with the obtained mixed powder, a pressurizing step of applying a pressure of 10.0 x 10 ² MPa to pressurize the filling material, and then a depressurizing step of depressurizing to atmospheric pressure were performed once. A molded body was produced by performing the following steps. The obtained molded body was heat-treated at a temperature of 130° C. for 1 hour to produce a bonded magnet, and its density and magnetic properties were evaluated. Table 2 shows the evaluation results of the composition of the magnet material, the density of the bonded magnet, the residual magnetization, and the maximum magnetic energy product. Remanent magnetization and maximum magnetic energy product were measured using a BH tracer.

(Comparative example 5)
A magnet material was produced in the same manner as in Example 10-16, and the magnet material was pulverized so that the average length was 100 μm or more and 200 μm or less. The pulverized powder, epoxy resin, and titanium coupling agent were weighed to be 97.0% by mass, 2.5% by mass, and 0.5% by mass, respectively, and an appropriate amount of acetone was added and mixed. Thereafter, the acetone was evaporated to prepare a mixed powder. After filling the mold with the obtained mixed powder, a pressurizing step of applying a pressure of 10.0 x 10 ² MPa to pressurize the filling material, and then a depressurizing step of depressurizing to atmospheric pressure were performed once. A molded body was produced. The obtained molded body was heat-treated at a temperature of 130° C. for 1 hour to produce a bonded magnet, and its density and magnetic properties were evaluated. Table 2 shows the evaluation results of the composition of the magnet material, the density of the bonded magnet, the residual magnetization, and the maximum magnetic energy product. Remanent magnetization and maximum magnetic energy product were measured using a BH tracer.

As shown in Table 2, the bonded magnet of Examples 17-21 has a high density of 6.45 g/cm ³ or more. This shows that the density of the bonded magnet can be improved by adjusting the manufacturing conditions of the bonded magnet.

Note that the above embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention, as well as within the scope of the invention described in the claims and its equivalents.

DESCRIPTION OF SYMBOLS 11... Permanent magnet motor, 13... Rotor, 14... Iron core, 15... Permanent magnet, 21... Variable magnetic flux motor, 23... Rotor, 24... Iron core, 25... Fixed magnet, 26... Variable magnet, 31... Generator, 32... Stator, 33... Rotor, 34... Turbine, 35... Shaft, 36... Brush, 100... Railway vehicle, 101... Rotating electric machine, 200... Automobile, 201... Rotating electric machine.

Claims (13)

Compositional formula 1: R _x Nb _y B _t M _100-xy-t
(R is at least one element selected from the group consisting of rare earth elements, M is at least one element selected from the group consisting of Fe and Co, and x satisfies 6.5<x≦8 atomic%. (y is a number that satisfies 0.75≦x/(x+y)≦0.95, and t is a number that satisfies 0≦t<12 atomic%)
is expressed by
comprising a main phase having at least one crystal phase selected from the group consisting of a TnMn type ₁₂ crystal phase and a TbCu type ₇ crystal phase,
z defined by z=(100-xy-t)/(x+y) is a number that satisfies 7.5≦z≦12 ,
A magnetic material having an intrinsic coercive force of 610 kA/m or more and a residual magnetization of 0.84 T or more, or having an intrinsic coercive force of 660 kA/m or more and a residual magnetization of 0.82 T or more. The magnetic material according to claim 1, wherein the t is a number satisfying 8≦t<12 atomic %. The magnetic material according to claim 1 or 2 , wherein 50 atomic % or more of the R element is Sm. The magnet material according to any one of claims 1 to 3 , wherein 50 atomic % or less of the Nb element is substituted with at least one element selected from the group consisting of Zr, Hf, and Ta. The magnetic material according to any one of claims 1 to 4 , wherein 50 atomic % or more of the M element is Fe. 20 atomic % or less of the M element is substituted with at least one element selected from the group consisting of Ni, Cu, V, Cr, Mn, Al, Si, Ga, Ta, W, Ti, and Mo. The magnetic material according to any one of claims 1 to 5 . The magnetic material according to any one of claims 1 to 6 , wherein the main phase has an average crystal grain size of 0.1 nm or more and 100 nm or less. The magnetic material according to any one of claims 1 to 7 ,
binder and
A permanent magnet. The permanent magnet according to claim 8 , wherein the permanent magnet has a density of 6.45 g/cm ³ or more. stator and
comprising a rotor;
A rotating electric machine, wherein the stator or the rotor includes the permanent magnet according to claim 8 or 9 . The rotating electrical machine according to claim 10 , wherein the rotor is connected to a turbine via a shaft. A vehicle comprising the rotating electric machine according to claim 10 . The vehicle according to claim 12 , wherein the rotor is connected to a shaft, and rotation is transmitted to the shaft.

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