JPWO2019187857A1 - Manufacturing method of RTB-based sintered magnet - Google Patents

Abstract

Atomizing method containing a step of preparing and preparing a plurality of R1-TB based sintered magnet materials having different compositions, R2: 65% by mass or more and 97% by mass or less, and M: 3% by mass or more and 35% by mass or less. The R2-M alloy powder is arranged between the step of preparing and preparing the R2-M alloy powder produced by the above and the plurality of R1-TB based sintered magnet materials, and the temperature is 450 ° C. or higher and 1000 ° C. or lower. A method for manufacturing an R-TB-based sintered magnet, which comprises a step of joining the plurality of R1-TB-based sintered magnet materials in the above.

Description

The present invention relates to a method for manufacturing an RTB-based sintered magnet.

R-TB-based sintered magnets (R is at least one of the rare earth elements and always contains Nd. T is Fe or Fe and Co and B is boron) are the highest among permanent magnets. Known as a high-performance magnet, it is used in various motors such as voice coil motors (VCM) for hard disk drives, motors for electric vehicles (EV, HV, PHV, etc.), motors for industrial equipment, and home appliances.

The RTB-based sintered magnet is mainly _{composed of a main phase composed of an R 2} T ₁₄ B compound and a grain boundary phase located at a grain boundary portion of the main phase. The main phase, R ₂ T ₁₄ B compound, is a ferromagnetic material with high saturation magnetization and anisotropic magnetic field, and forms the basis of the characteristics of R-TB based sintered magnets.

At high temperatures, the coercive force H _cJ (hereinafter, may be simply referred to as “H _cJ ”) of the RTB-based sintered magnet decreases, so that irreversible thermal demagnetization occurs. _{Therefore, the RTB} -based sintered magnet used in the motor for electric vehicles is required to have a high H cJ.

In the RTB-based sintered magnet, a part of the light rare earth element RL (for example, Nd or Pr) contained in R _{in the R 2} T _{14 B compound is used as the heavy rare earth element RH (for example, Dy or Tb).} Substitution is known to improve _{H cJ. H cJ} improves as the amount of RH substitution increases.

However, substitution with RH to RL in R ₂ T ₁₄ B compound, while improving H _cJ of the R-T-B-based sintered magnet, the remanence B _r (hereinafter, simply referred to as "B _r" is There is) decreases. In particular, Dy and Tb heavy rare earth elements have problems such as unstable supply and large price fluctuations due to the small amount of resources present and the limited production areas. ing. Therefore, in recent years, it has been required to improve _{H cJ} without using heavy rare earth elements of Dy and Tb as much as possible.

In Patent Document 1, a unit magnet having a relatively high content of heavy rare earth elements such as Dy is arranged in a portion where _{H cJ} needs to be increased in order to suppress the amount of heavy rare earth elements used, and a unit magnet having a relatively high content of heavy rare earth elements is arranged in other portions. Discloses a technique for joining a plurality of unit magnets by arranging unit magnets having a relatively low content of heavy rare earth elements. The joint surface of the unit magnet is heated in a state of being in contact with each other through a paste in which a metal powder containing a heavy rare earth element and an organic substance are mixed.

Patent Document 2 discloses a technique for joining an RTB-based rare earth sintered magnet and a heterogeneous member such as a silicon steel plate via an alloy powder of a rare earth element and another metal element.

JP-A-2015-73045 Japanese Unexamined Patent Publication No. 8-116633

According to the joining technique disclosed in Patent Document 1, a unit magnet having a relatively high content of heavy rare earth elements such as Dy and a unit magnet having a relatively low content of heavy rare earth elements are arranged. Therefore, the amount of heavy rare earth elements used can be reduced. However, the bonding surfaces of the unit magnets are bonded by heating in contact with each other through a paste in which a metal powder containing a heavy rare earth element and an organic substance are mixed (that is, they are bonded by diffusion of the heavy rare earth element). ing).

In recent years, in applications such as motors for electric vehicles, RTB-based sintered magnets having _{high H cJ without using Dy and Tb have been required.} Further, the joining technique disclosed in Patent Documents 1 and 2 can join RTB-based rare earth sintered magnets or RTB-based rare earth sintered magnets and iron-based metal members. It will be possible. However, as a result of the study by the present inventor, it has been found that a new bonding technique capable of achieving higher bonding strength is required when used in a motor or the like that requires high-speed rotation.

Various embodiments of the present invention, while achieving a high bonding strength, to provide a method of manufacturing a R-T-B based sintered magnet having a high B _r and high H _cJ without using Dy and Tb ..

In the method for producing an RTB-based sintered magnet of the present disclosure, in an exemplary embodiment, a plurality of R1-TB-based sintered magnet materials having different compositions (R1 contains at least one of Nd and Pr). Rare earth element including) and R2: 65% by mass or more and 97% by mass or less (R2 is a rare earth element containing at least one of Nd and Pr, and the total content of Dy and Tb with respect to the whole R2 is 50. (M by mass% or less), and M: 3% by mass or more and 35% by mass or less (M is at least one selected from the group consisting of Ga, Cu, In, Al, Sn and Co), and the atomizing method. The R2-M alloy powder is arranged between the step of preparing and preparing the R2-M alloy powder produced by the above and the plurality of R1-TB-based sintered magnet materials, and the temperature is 450 ° C. or higher and 1000 ° C. or lower. Includes the step of joining the plurality of R1-TB based sintered magnet materials.

In certain embodiments, the total content of Dy and Tb relative to R2 as a whole is 15% by weight or less.

In certain embodiments, R2 always contains Pr and M always contains Ga.

In a certain embodiment, the plurality of R1-TB based sintered magnet materials are the first R1-TB based sintered magnet material having a relatively high coercive force and the first R1-TB based sintered magnet material having a relatively low coercive force. 2 R1-TB based sintered magnet material is included.

In a certain embodiment, at least one of the first R1-TB based sintered magnet material and the second R1-TB based sintered magnet material has a thickness of 2 mm or less.

In a certain embodiment, at least one of the first R1-TB based sintered magnet material and the second R1-TB based sintered magnet material has a thickness of 1 mm or less.

According to the embodiment of the present disclosure, since the bonding is performed using the powder of the R2-M alloy powder produced by the atomization method, the bonding is performed with high bonding strength, and high B without using Dy and Tb. _{An RTB} -based sintered magnet having _r and H cJ can be produced.

It is sectional drawing which shows the part of the RTB-based sintered magnet by enlarging and empirically. It is sectional drawing which shows the inside of the broken line rectangular area of FIG. 1A by further enlarging. It is a schematic cross-sectional view of the alloy powder formed by the conventional pulverization. It is a schematic cross-sectional view of the alloy powder formed by the atomizing method according to the embodiment of this disclosure. It is a perspective view which shows typically the state before joining of the R1-TB system sintered magnet material by embodiment of this disclosure. It is a perspective view which shows typically the state during joining of the R1-TB system sintered magnet material by embodiment of this disclosure. It is a flowchart which shows the example of the process in the manufacturing method of the RTB system sintered magnet by the embodiment of this disclosure.

FIG. 1A is a cross-sectional view schematically showing an enlarged part of an RTB-based sintered magnet, and FIG. 1B is a cross-sectional view schematically showing the inside of the broken line rectangular region of FIG. 1A in an enlarged manner. Is. In FIG. 1A, as an example, an arrow having a length of 5 μm is shown for reference as a reference length indicating the size. As shown in FIGS. 1A and 1B, the RTB-based sintered magnet has a _{main phase 12 mainly composed of the R 2} T ₁₄ B compound and a grain boundary phase 14 located at the grain boundary portion of the main phase 12. It is composed of and. The grain boundary phase 14, as shown in FIG. 1B, 2 two R ₂ T ₁₄ B compound particles (grains) and a second grain grain boundary phase 14a adjacent grain three R ₂ T ₁₄ B compound particles adjacent Including the boundary triple point 14b.

_{The R 2} T ₁₄ B compound, which is the main phase 12, is a ferromagnetic material having a high saturation magnetization and an anisotropic magnetic field. Therefore, in the R-T-B based sintered magnet, it is possible to improve the B _r by increasing the existence ratio of R ₂ T ₁₄ B compound is the main phase 12. In _{order to increase the abundance ratio of the R 2} T ₁₄ B compound, the R amount, T amount, and B amount in the raw material alloy _{are set to the stoichiometric ratio of the R 2} T ₁₄ B compound (R amount: T amount: B amount = It should be close to 2:14: 1).

_{The present inventor modifies the} grain boundary phase and enhances H cJ by diffusing at least one selected from the group consisting of Ga, Cu, In, Al, Sn and Co together with R into the grain boundaries. Turned out to be possible. For such modification of the grain boundary phase, an R1-TB based sintered magnet material (R1 is a rare earth element containing at least one of Nd and Pr) is prepared, and R1-TB based sintered. It is preferable to supply the metal element M (at least one selected from the group consisting of Ga, Cu, In, Al, Sn and Co) from the surface of the magnet material to the grain boundaries to diffuse the inside of the grain boundaries. Such diffusion of the metal element M is an alloy of R2 (rare earth element containing at least one of Nd and Pr) of 65% by mass or more and 97% by mass or less and M of 3% by mass or more and 35% by mass or less, that is, R2. It can be carried out using a powder of −M alloy. Thus, it is possible to obtain the R-T-B based sintered magnet having a high B _r and high H _cJ without using Dy and Tb.

As a result of further studies, the present inventor applies R2-M alloy powder (atomized powder of R2-M alloy) produced by the atomizing method to the surface of the R1-TB alloy sintered magnet material for diffusion. It has been found that when the heat treatment is performed, it can be used as an excellent welding agent for joining other solid members to the R1-TB based sintered magnet material. That is, the atomized powder of the R2-M alloy functions as a diffusion source for introducing into the two-particle boundary, and also as a powder that joins the surfaces of the R1-TB-based sintered magnets and uniformly bonds them. It turns out that it can work. This is because the shape and size distribution of the atomized powder particles is more uniform than that of the powder particles formed by pulverizing the R2-M alloy. As a result, nests are less likely to be formed on the joint surface, and the joint strength is improved.

FIG. 2 is a schematic cross-sectional view of an alloy powder 50 formed by conventional pulverization (for example, a raw material alloy produced by an ingot method or a strip casting method and then pulverized). The alloy powder is arranged between the two solid members 20 and is located in the void created by the opposing surfaces (bonded surfaces) 20S of the members 20. As can be seen from FIG. 2, the shapes and sizes of the individual powder particles 50P are different. Since the alloy powder 50 is produced by crushing an alloy, the particles 50P have flat portions, acute-angled convex portions, complicated fracture surfaces, and the like.

On the other hand, FIG. 3 is a schematic cross-sectional view of the R2-M alloy powder 30 formed by the atomizing method according to the embodiment of the present disclosure. As shown in FIG. 3, the individual particles 30P constituting the R2-M alloy powder 30 formed by the atomization method are spherical. Such spherical powder particles 30P are arranged between the surfaces (bonded surfaces) 20S of the facing solid members 20, and when the surfaces 20S of the solid members 20 are brought close to each other, the voids formed by the facing surfaces 20S are uniform. Can be rearranged to fill in. Therefore, it is possible to increase the degree of adhesion of the joint surface 20S without forming unnecessary nests at the time of joining.

FIG. 4 is a perspective view schematically showing a state before joining the R1-TB based sintered magnet material according to the embodiment of the present disclosure. In the illustrated example, the R1-TB based sintered magnet materials 22, 24, and 26 are laminated. A first R1-TB based sintered magnet material 22 located at the lower end and a second R1-TB based sintered magnet material 24 located at the center were formed by an atomizing method. A layer of R2-M alloy powder 30 is formed. Similarly, the atomizing method is also applied between the second R1-TB based sintered magnet material 24 located at the center and the third R1-TB based sintered magnet material 26 located at the upper end. A layer of R2-M alloy powder 30 formed by is formed. In the example of FIG. 4, the R2-M alloy powder 30 is applied to the upper surface of the first R1-TB based sintered magnet material 22 and the upper surface of the second R1-TB based sintered magnet material 24. Has been done. However, the R2-M alloy powder 30 formed by the atomizing method is the bottom surface of the second R1-TB based sintered magnet material 24 and / or the third R1-TB based sintered magnet material 26. It may be applied to the bottom surface, or may be applied to the entire surface of the second R1-TB based sintered magnet material or the entire surface of the first and third R1-TB based sintered magnets. Good.

FIG. 5 is a perspective view schematically showing a state during joining of the R1-TB based sintered magnet material according to the embodiment of the present disclosure. In the state shown in FIG. 5, the first R1-TB-based sintered magnet material 22 and the second R1-TB-based sintered magnet material 24 are close to each other with the R2-M alloy powder 30 interposed therebetween. The second R1-TB-based sintered magnet material 24 and the third R1-TB-based sintered magnet material 26 are close to each other with the R2-M alloy powder 30 interposed therebetween.

In some embodiments, pressure may be applied in the stacking direction. By performing the heat treatment in the state shown in FIG. 5, the R2-M alloy powder is melted, and the first R1-TB-based sintered magnet material 22 and the second R1-TB-based sintered magnet material 22 are used. The 24 is joined, and the second R1-TB-based sintered magnet material 24 and the third R1-TB-based sintered magnet material 2 are joined. In this way, an RTB-based sintered magnet in which these magnet materials are integrated is produced.

In this joining step, the rare earth element R2 and the metal element M contained in the R2-M alloy powder 30 enter the inside from the joining surface of the R1-TB based sintered magnet materials 22, 23, 24 via grain boundaries. Spread. The R2-M alloy powder 30 produced by the atomizing method functions not only as a diffusion source but also as an excellent bonding aid and contributes to the improvement of bonding strength.

R2-M alloys such as Pr-Ga alloys have high ductility and generally have poor grindability. Therefore, it takes a long time to grind, and there is a problem in mass productivity. In the embodiment of the present disclosure, by using the atomized powder of the R2-M alloy, powder particles (for example, particles having a particle size of 200 μm or less) can be obtained without pulverization.

As illustrated in FIG. 6, the method for producing an RTB-based sintered magnet according to the present disclosure is produced by a step S10 for preparing a plurality of R1-TB-based sintered magnet materials and an atomizing method. The step S20 for preparing the R2-M alloy powder is included. The order of the step S10 for preparing a plurality of R1-TB-based sintered magnet materials and the step S20 for preparing the R2-M alloy powder produced by the atomization method is arbitrary, and each is manufactured at a different place. R1-TB based sintered magnet material and R2-M alloy atomized powder may be used.

Further, the method for manufacturing the RTB-based sintered magnet according to the present disclosure includes a step S30 of arranging the R2-M alloy powder between the plurality of R1-TB-based sintered magnet materials and a plurality of R1-T. Includes step S40 for joining the −B-based sintered magnet material.

Hereinafter, embodiments of the method for manufacturing the RTB-based sintered magnet of the present disclosure will be described in more detail.

1. 1. Step of Preparing R1-TB-based Sintered Magnet Material First, a plurality of R1-TB-based sintered magnet materials are prepared. The R1-TB-based sintered magnet material may be any known R-TB-based sintered magnet. A typical example of the R1-TB based sintered magnet material that can be used in this embodiment has the following composition.
Rare earth element R1: 27.5 to 35.0% by mass
B (a part of B (boron) may be replaced with C (carbon)): 0.80 to 0.99% by mass
Ga: 0 to 0.8% by mass
Additive metal element M (at least one selected from the group consisting of Al, Cu, Zr, Nb): 0 to 2% by mass
T (a transition metal element mainly containing Fe, which may contain Co) and unavoidable impurities: balance

Further, preferably, the following inequality (1) is satisfied.
[T] /55.85> 14 [B] /10.8 (1)
Here, [T] is the content of T represented by mass%, and [B] is the content of B represented by mass%.

The fact that satisfies this inequality, the content of B is less than the stoichiometric ratio of the R ₂ T ₁₄ B compound, i.e., the main phase (R ₂ T ₁₄ B compound) T amount used for formation to This means that the amount of B is relatively small.

By diffusing R2-M alloy powder against R1-T-B based sintered magnet material satisfying the formula (1), that without using Dy and Tb to obtain a higher B _r and H _cJ Can be done.

The rare earth element R1 is mainly a light rare earth element RL (at least one element selected from Nd and Pr), but may contain a heavy rare earth element such as Dy and Tb. However, the amount of heavy rare earth elements such as Dy and Tb used is preferably 2% or less of the total amount of the R1-TB based sintered magnet material, and most preferably the R1-TB based sintered magnet material is Dy. And does not contain heavy rare earth elements such as Tb (including unavoidable impurities).

In the embodiment of the present disclosure, in the example shown in FIG. 4, the composition of one or both of the first R1-TB-based sintered magnet material 22 and the third R1-TB-based sintered magnet material 26. Is different from the composition of the second R1-TB based sintered magnet material 24. Of the plurality of R1-TB-based sintered magnet materials to be joined, at least one R1-TB-based sintered magnet material has a higher retention rate than other R1-TB-based sintered magnet materials. A small amount of at least one of Dy and Tb may be contained as a heavy rare earth element so as to achieve a magnetic force H _cJ. For example, when a part of one R1-TB based sintered magnet is required to exhibit a high coercive force H _{cJ, it is selective for some R1-TB based sintered magnet materials.} May be added with heavy rare earth elements. However, since it is preferable not to use Dy and Tb as much as possible, the total content of Dy and Tb is preferably 5% or less, more preferably 1% or less, and most preferably Dy of the entire R1-TB based sintered magnet. And Tb are not contained. The R1-TB based sintered magnet material having the above composition can be produced by any known production method. The R1-TB based sintered magnet material may be sintered, or may be cut or polished.

In the example shown in FIG. 4, the first and third R1-TB based sintered magnet materials 22 and 26 can be made thinner than the second R1-TB based sintered magnet material 24. For example, the thickness of the first and third R1-TB based sintered magnet materials 22 and 26 is 2 mm or less (or 1 mm or less), and the thickness of the second R1-TB based sintered magnet material 24 is The thickness can be greater than 2 mm (or greater than or equal to 1 mm).

2. Step of preparing R2-M alloy powder produced by the atomizing method (R2) R2 is a rare earth element containing at least one of Nd and Pr, and the total content of Dy and Tb with respect to the whole R2 is 50% by mass or less. is there. For example, when R2 is 80% by mass of the entire R2-M alloy, the total content of Dy and Tb is 40% by mass or less. Preferably, the total content of Dy and Tb with respect to the whole R2 is 15% by mass or less. Most preferably, the R2-M alloy powder does not contain heavy rare earth elements such as Dy and Tb (contains unavoidable impurities). R2 is 65% by mass or more and 97% by mass or less of the entire R2-M alloy. R2 always contains Pr, and the amount of Pr in R2 is preferably 40% by mass or more, more preferably 70% by mass or more.
(M) M is at least one selected from the group consisting of Ga, Cu, In, Al, Sn and Co. M is 3% by mass or more and 35% by mass or less of the entire R2-M alloy. M preferably always contains Ga, and the amount of Ga in M is 50% by mass or more. The R2-M alloy may contain unavoidable impurities. Most preferably, an R2-M alloy powder having an amount of Pr in R2 of 70% by mass or more and an amount of Ga in M of 50% by mass or more is used. As a result, Ga can be introduced into the two-particle boundary with almost no introduction into the main phase crystal grains. By introducing the liquid phase containing Ga into the two-particle boundary, high H _cJ can be obtained without using Dy or Tb.

In the embodiments of the present disclosure, the R2-M alloy powder is produced by the atomizing method. The atomizing method is one of the powder producing methods also called the molten metal spraying method, and includes known atomizing methods such as a gas atomizing method and a plasma atomizing method. For example, according to the gas atomization method, a metal or alloy is melted in a melting furnace to form a molten metal, and the molten metal is sprayed into an atmosphere of an inert gas such as nitrogen or argon to solidify. Since the sprayed molten metal scatters as fine droplets, it is cooled at a high speed and solidifies. Since each of the powder particles produced has a spherical shape, it is not necessary to pulverize the powder particles. The size of the powder particles produced by the atomizing method is distributed in the range of, for example, 10 μm to 200 μm.

According to the atomizing method, the droplets of the molten alloy to be sprayed are small, and the surface area is relatively large with respect to the weight of each droplet, so that the cooling rate is high. Therefore, the powder particles formed are amorphous or microcrystalline. In addition, these powder particles may be additionally heat-treated before the joining step to crystallize the amorphous material.

The particle size of the R2-M alloy powder can be adjusted by sieving. Further, if the amount of powder excluded by sieving is within 10% by mass, the effect is small, so that the powder may be used without sieving.

3. 3. Step of arranging R2-M alloy powder between a plurality of R1-TB based sintered magnet materials The R2-M alloy powder is arranged between R1-TB based sintered magnet materials (in other words, in other words. R2-M alloy powder is sandwiched between a plurality of R1-TB based sintered magnet materials). The arrangement method may be performed by applying R2-M alloy powder to the surfaces of both R1-TB-based sintered magnet materials, or the surface of one R1-TB-based sintered magnet material. R2-M alloy powder may be simply applied to the surface. Further, the R2-M alloy powder may be applied to the entire surface of the R1-TB based sintered magnet material, or may be only the joint surface as shown in FIG. Further, two or more kinds of R2-M alloy powders having different compositions may be used. The method of applying the R2-M alloy powder to the surface of a plurality of R1-TB based sintered magnet materials is not limited to a specific coating method. A coating step of applying the pressure-sensitive adhesive to the surface to be coated and a step of adhering the R2-M alloy powder to the area to which the pressure-sensitive adhesive is applied may be performed. Examples of the pressure-sensitive adhesive include PVA (polyvinyl alcohol), PVB (polyvinyl butyral), PVP (polyvinylpyrrolidone) and the like. When the pressure-sensitive adhesive is a water-based pressure-sensitive adhesive, the RTB-based sintered magnet material may be preheated before coating. The purpose of preheating is to remove excess solvent to control the adhesive strength and to evenly adhere the adhesive. The heating temperature is preferably 60 to 100 ° C. This step may be omitted in the case of a highly volatile organic solvent-based pressure-sensitive adhesive.

Any method may be used for applying the adhesive to the surface of the RTB-based sintered magnet material. Specific examples of coating include a spray method, a dipping method, and coating with a dispenser. The amount of the pressure-sensitive adhesive applied may be, for example, 1.02 × 10 ^{-5 to} 5.10 × 10 ^-5 g / mm ² .

4. Step of joining a plurality of R1-TB based sintered magnets According to the present disclosure, for joining in a state where the R1-TB based sintered magnet material and the R2-M alloy powder (atomized powder) are in contact with each other. Start the heat treatment of. As a result, while achieving a high bonding strength, R1-T-B based sintered magnet of the grain boundary phase to realize a reformed with high B _r and H _cJ throughout the internal magnet.

The heat treatment for joining can be carried out at a temperature of 450 ° C. or higher and 1000 ° C. or lower for a time of 5 minutes or more and 720 minutes or less. The heat treatment may be performed at a relatively high temperature (700 ° C. or higher and 1000 ° C. or lower) and then at a relatively low temperature (450 ° C. or higher and 600 ° C. or lower) (two-stage heat treatment). Preferred conditions are heat treatment at 730 ° C. or higher and 980 ° C. or lower for about 5 to 500 minutes, after cooling (after cooling to room temperature or after cooling to 440 ° C. or higher and 550 ° C. or lower), and further at 440 ° C. or higher and 550 ° C. or lower. Heat treatment may be performed for about 1 to 500 minutes. The atmosphere gas for heat treatment can be nitrogen or an inert gas. The atmospheric gas may be depressurized.

The present disclosure will be described in more detail by way of examples, but the present disclosure is not limited thereto.

Experimental Example 1
The R1-TB based sintered magnet material is No. 1 in Table 1. Each element was weighed and cast by a strip casting method so as to have the compositions shown in 1-A and 1-B to obtain a flake-shaped alloy. The obtained flake-shaped alloy was hydrogen embrittled in a hydrogen-pressurized atmosphere, and then dehydrogenated by heating and cooling in a vacuum up to 550 ° C. to obtain coarsely pulverized powder. Next, to the obtained coarsely pulverized powder, 0.04% by mass of zinc stearate was added as a lubricant to 100% by mass of the coarsely pulverized powder, mixed, and then using an airflow type crusher (jet mill device). , Dry pulverization in a nitrogen atmosphere to obtain an alloy powder having _{a particle size D 50 of 4.3 μm.} A liquid lubricant was added to the alloy powder in an amount of 0.3% by mass based on 100% by mass of the finely pulverized powder, mixed, and then molded in a magnetic field to obtain a molded product. As the molding apparatus, a so-called right-angle magnetic field forming apparatus (transverse magnetic field forming apparatus) in which the magnetic field application direction and the pressurizing method direction are orthogonal to each other was used. The obtained molded product was sintered in vacuum at 1000 ° C. or higher and 1050 ° C. or lower (select a temperature at which sufficient densification occurs by sintering for each sample) for 4 hours, and an R1-TB-based sintered magnet material (R1-TB-based sintered magnet material). A plurality of No. 1-A and 1-B) were prepared. The density of the sintered magnet was 7.5 Mg / m ³ or more. Further, the obtained R1-TB-based sintered magnet material was machined to obtain a length of 10 mm, a width of 5 mm, and a thickness of 3 mm (thickness is the magnetization direction). Table 1 shows the results of the components of the obtained R1-TB sintered magnet material. Each component in Table 1 was measured using high frequency inductively coupled plasma emission spectroscopy (ICP-OES). Further, all the R1-TB based sintered magnet materials satisfied the inequality (1).

Next, No. in Table 2 An R2-M alloy powder was prepared by producing an alloy powder having the composition shown in 1-a by an atomizing method. The particle size of the obtained R2-M alloy powder was 106 μm or less. Furthermore, No. in Table 2 Each element was weighed so as to obtain an alloy having the composition shown in 1-b and cast by a strip casting method to obtain a flake-shaped alloy. The obtained flake-shaped alloy was hydrogen embrittled in a hydrogen-pressurized atmosphere, and then dehydrogenated by heating and cooling in a vacuum up to 550 ° C. to obtain coarsely pulverized powder. Zinc stearate as a lubricant was added to the obtained coarsely pulverized powder in an amount of 0.04% by mass based on 100% by mass of the coarsely pulverized powder, mixed, and then a nitrogen atmosphere was used using an air flow type pulverizer (jet mill device). Dry pulverization was performed in the medium to obtain an alloy powder having a particle size D _{50 of 4.3 μm.}

Next, No. 1 in Table 1. An adhesive was applied to the entire surface of the 1-A and 1-B R1-TB based sintered magnet materials. As a coating method, the R1-TB based sintered magnet material was heated to 60 ° C. on a hot plate, and then an adhesive was applied to the R1-TB based sintered magnet material by a spray method. PVP (polyvinylpyrrolidone) was used as the pressure-sensitive adhesive.

Next, with respect to the R1-TB based sintered magnet materials (No. 1-A and 1-B) coated with the adhesive, No. 1 in Table 2 was applied. A diffusion source of 1-a (R2-M alloy powder) was attached. The method of attachment is to spread the diffusion source in the container, cool the R1-TB-based sintered magnet material coated with the adhesive to room temperature, and then use the diffusion source in the container as the R1-TB-based sintered magnet material. It was attached so as to be sprinkled on the entire surface.

Next, the R1-TB system is in contact with the R1-TB system sintered magnet materials (No. 1-A and 1-B) and the R2-M alloy powder (No. 1-a). Sintered magnet material No. The R1-TB based sintered magnet material is joined by stacking 1-A and 1-B in the thickness (3 mm) direction (contacting the surfaces of 10 mm in length × 5 mm in width) and performing heat treatment. , RTB-based sintered magnet (No. 1-1) was obtained. The heat treatment was carried out at 900 ° C. for 8 hours, then cooled to room temperature, and further heat-treated at 500 ° C. for 6 hours (two-stage heat treatment). In the same manner, with respect to the R1-TB based sintered magnet materials (No. 1-A and 1-B), No. 1 in Table 2 was used. A diffusion source of 1-b is attached, and heat treatment is performed in the same manner to bond the R1-TB-based sintered magnet material to obtain an R-TB-based sintered magnet (No. 1-2). It was.

The generation of cavities on the joint surface of the obtained RTB-based sintered magnet was confirmed. If many nests occur, the adhesive strength may decrease or peeling may occur starting from the nests. Therefore, RTB-based sintered magnets are used especially for motors that need to rotate at high speed. If so, it is necessary to suppress the development of nests.

RTB-based sintered magnets (No. 1-1 and 1-2) are cut and polished by machining, respectively, and the cross section of any bonded magnet including the bonded surface (magnet cross section at width 5 mm x thickness 6 mm) is obtained. It was observed with a scanning electron microscope (SEM: JCM-7001F manufactured by JEOL Ltd.). The observation area was 500 μm × 500 μm, and the occurrence of nests on the joint surface was confirmed by visual inspection. According to the present invention, the occurrence of nests is 10% or less of the joint surface (100 × area of nest portion / area of joint portion). The results are shown in Table 3. When the occurrence of nests is 10% or less, it is described as 〇, and when it exceeds 10%, it is described as ×. Further, Table 3 shows the results of the magnetic characteristics of the RTB-based sintered magnet. The magnetic properties were measured using a BH tracer.

As shown in Table 3, the example of the present invention suppresses the generation of nests, whereas the comparative example (when a diffusion source prepared by the strip cast method is used) does not suppress the generation of nests.

Experimental Example 2
Approximately No. in Table 4. An R1-TB based sintered magnet material was prepared in the same manner as in Experimental Example 1 so as to have the compositions shown in 2-A and 2-B. The obtained R1-TB-based sintered magnet material was machined to obtain a length of 10 mm, a width of 5 mm, and a thickness of 3 mm (thickness is the magnetization direction). Table 4 shows the results of the components of the obtained R1-TB sintered magnet material. Each component in Table 4 was measured using high frequency inductively coupled plasma emission spectroscopy (ICP-OES). Further, No. 1 of Experimental Example 1. 1-A and 1-B R1-TB based sintered magnet materials were prepared.

Next, No. in Table 5 The R2-M alloy powder was prepared by producing the alloy powder having the compositions shown in 2-a to 2-e by the atomizing method. Further, the R2-M alloy powder of 1-a of Experimental Example 1 was prepared. The particle size of the obtained R2-M alloy powder was 106 μm or less.

Next, under the conditions shown in Table 6, the R1-TB-based sintered magnet material was bonded in the same manner as in Experimental Example 1 to obtain an R-TB-based sintered magnet. No. in Table 6 2-1 is No. 1-A and 1-B R1-TB based sintered magnet material An adhesive was applied to the entire surface of the surface in the same manner as in Experimental Example 1, and the adhesive was applied to the R1-TB based sintered magnet material ( No. 1-A and 1-B) The R-2M alloy powder of 2-a was attached in the same manner as in Experimental Example 1. Next, the R1-TB system is in contact with the R1-TB system sintered magnet materials (No. 1-A and 1-B) and the R2-M alloy powder (No. 2-a). Sintered magnet material No. By stacking 1-A and 1-B in the thickness direction (3 mm) and performing heat treatment in the same manner as in Experimental Example 1, the R1-TB-based sintered magnet material is bonded, and the R-TB-based A sintered magnet (No. 2-1) was obtained. No. 2-2-2-7 are also described in the same manner. With respect to the obtained RTB-based sintered magnet, the occurrence of cavities on the joint surface was visually confirmed in the same manner as in Experimental Example 1. Further, the magnetic characteristics of the RTB-based sintered magnet were measured. The results are shown in Table 6.

As shown in Table 6, in all the examples of the present invention, the generation of nests is suppressed.

According to the present invention, it is possible to produce R-T-B based sintered magnet having a high B _r and high H _cJ. The sintered magnet of the present invention is suitable for various motors such as motors for mounting on hybrid vehicles exposed to high temperatures, home appliances, and the like.

12 R ₂ T ₁₄ B Main phase 14 grain boundary phase 14a Two grain boundary phase

14b Grain boundary triple point 20 Solid member 30 R2-M alloy powder 22, 24, 26 R1-TB based sintered magnet material 50 Alloy powder

Claims (6)

A plurality of R1-TB based sintered magnet materials having different compositions (R1 is a rare earth element containing at least one of Nd and Pr, T is a transition metal element mainly containing Fe, and may contain Co. ) And the process of preparing
R2: 65% by mass or more and 97% by mass or less (R2 is a rare earth element containing at least one of Nd and Pr, and the total content of Dy and Tb with respect to R2 is 50% by mass or less), and M: 3. Mass% or more and 35 mass% or less (M is at least one selected from the group consisting of Ga, Cu, In, Al, Sn and Co)
And the step of preparing the R2-M alloy powder produced by the atomizing method.
The R2-M alloy powder is placed between the plurality of R1-TB based sintered magnet materials, and the plurality of R1-TB based sintered magnet materials are bonded at a temperature of 450 ° C. or higher and 1000 ° C. or lower. And the process to do
A method for producing an RTB-based sintered magnet, which comprises the above. The method for producing an RTB-based sintered magnet according to claim 1, wherein the total content of Dy and Tb with respect to the entire R2 is 15% by mass or less. The method for producing an RTB-based sintered magnet according to claim 1 or 2, wherein R2 always contains Pr and M always contains Ga. The plurality of R1-TB-based sintered magnet materials include a first R1-TB-based sintered magnet material having a relatively high coercive force and a second R1-T having a relatively low coercive force. The method for producing an RT-B-based sintered magnet according to any one of claims 1 to 3, which includes a −B-based sintered magnet material. Claims 1 to 4, wherein at least one of the first R1-TB-based sintered magnet material and the second R1-TB-based sintered magnet material has a thickness of 2 mm or less. The method for manufacturing an RTB-based sintered magnet according to any one of the above. Claims 1 to 5, wherein at least one of the first R1-TB-based sintered magnet material and the second R1-TB-based sintered magnet material has a thickness of 1 mm or less. The method for manufacturing an RTB-based sintered magnet according to any one of the above.

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