JP2019176122A - Method for manufacturing r-t-b based sintered magnet - Google Patents

Abstract

To provide a method for manufacturing an R-T-B based sintered magnet having high Band high Hwithout Dy nor Tb while achieving a high connection strength.SOLUTION: A method for manufacturing an R-T-B based sintered magnet comprises the steps of: preparing an R1-T-B based sintered magnet material; preparing an insulating member; and preparing R2-M alloy powder produced by an atomization method, provided that R2 is 65 mass% or more and 97 mass% or less and M is 3 mass% or more and 35 mass% or less. The method further comprises a bonding step of disposing the R2-M alloy powder between the R1-T-B based sintered magnet material and the insulating member and bonding the R1-T-B based sintered magnet material and the insulating member at a temperature of 450°C or higher and 1000°C or lower.SELECTED DRAWING: Figure 6

Description

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

  R-T-B based sintered magnets (R is at least one of rare earth elements and always contains Nd. T is Fe or Fe and Co, and B is boron) is the highest among permanent magnets. It is known as a high-performance magnet, and 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 composed of a main phase mainly composed of an R ₂ T ₁₄ B compound and a grain boundary phase located at the grain boundary portion of the main phase. The main phase R ₂ T ₁₄ B compound is a ferromagnetic material having a high saturation magnetization and an anisotropic magnetic field, and forms the basis of the characteristics of the RTB-based sintered magnet.

At a high temperature, the coercive force H _cJ (hereinafter sometimes simply referred to as “H _cJ ”) of the _RTB -based sintered magnet decreases, and irreversible thermal demagnetization occurs. Therefore, an _RTB -based sintered magnet used particularly for an electric vehicle motor is required to have a high _HcJ .

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 a heavy rare earth element RH (for example, Dy or Tb). Substitution is known to improve _HcJ . As the substitution amount of RH increases, _HcJ improves.

However, when RL in the R ₂ T ₁₄ B compound is replaced with RH, the H _{cJ of the RTB} -based sintered magnet is improved, while the residual magnetic flux density B _r (hereinafter simply referred to as “B _r ”). There is). In particular, heavy rare earth elements such as Dy and Tb have problems such as the supply is not stable and the price fluctuates greatly due to the small amount of resources and the limited production area. ing. Therefore, in recent years, it has been demanded to improve _HcJ without using heavy rare earth elements of Dy and Tb as much as possible.

In Patent Document 1, in order to suppress the use amount of heavy rare earth elements, unit magnets having a relatively large content of heavy rare earth elements such as Dy are arranged in portions where _HcJ needs to be increased, and other portions are arranged. Discloses a technique in which unit magnets having a relatively small content of heavy rare earth elements are arranged and these unit magnets are joined. The joint surface of the unit magnet is heated while being in contact with a metal powder containing a heavy rare earth element and an organic substance mixed paste.

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

Japanese Patent Laying-Open No. 2015-73045 JP-A-8-116633

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

In recent years, in applications such as electric vehicle motors, RTB-based sintered magnets having high _HcJ without using Dy and Tb have been demanded. Moreover, the joining technique currently disclosed by patent document 1 and 2 is joining the R-T-B type rare earth sintered magnets, or the R-T-B type rare earth sintered magnet and an iron-type metal member. It becomes possible. However, as a result of examination by the present inventors, it has been found that a new joining technique capable of realizing higher joining strength is required when used in a motor or the like that needs to rotate at high speed.

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 exemplary embodiment, the manufacturing method of the RTB-based sintered magnet of the present disclosure uses an R1-TB-based sintered magnet material (R1 is a rare earth element including at least one of Nd and Pr). A step of preparing, a step of preparing and preparing an insulating member, and R2: 65% by mass or more and 97% by mass or less (R2 is a rare earth element including at least one of Nd and Pr, and the total content of Dy and Tb relative to the entire R2 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). The step of preparing the R2-M alloy powder prepared by the atomizing method, the R2-M alloy powder is disposed between the R1-T-B system sintered magnet material and the insulating member, and 450 ° C. Above 1000 ℃ Including, a bonding step of bonding the insulating member and the R1-T-B based sintered magnet material in degrees.

  In one embodiment, R2 does not contain Dy and Tb (including unavoidable impurities), and the total content of Dy and Tb is 15% by mass or less based on the entire R2.

  In some embodiments, R2 necessarily contains Pr and M necessarily contains Ga.

  In one embodiment, the insulating member is a sheet formed from mica.

  In one embodiment, the R1-T-B based sintered magnet material has an average thickness of 2 mm or less.

  In one embodiment, the R1-T-B based sintered magnet material has an average thickness of 1 mm or less.

  In one embodiment, the joining step includes a step of laminating three or more layers of R1-T-B-based sintered magnet material via the insulating member.

According to embodiments of the present disclosure, for performing bonded using powder R2-M alloy powder made by atomizing method, while realizing a high bonding strength, high without using Dy and Tb B _{r And} an _RTB -based sintered magnet having _HcJ can be manufactured.

It is sectional drawing which expands and partially shows a part of RTB system sintered magnet. FIG. 1B is a cross-sectional view schematically showing a further enlarged view of a broken-line rectangular region in FIG. 1A. It is typical sectional drawing of the alloy powder formed by the conventional grinding | pulverization. It is a typical sectional view of the alloy powder formed by the atomization method by the embodiment of this indication. It is a perspective view showing typically the state before joining of the R1-T-B system sintered magnet material by the embodiment of this indication. It is a perspective view showing typically the state under joining of the R1-T-B system sintered magnet material by the embodiment of this indication. It is a flowchart which shows the example of the process in the manufacturing method of the RTB type sintered magnet by embodiment of this indication.

FIG. 1A is a cross-sectional view schematically showing a part of an R-T-B system sintered magnet in an enlarged manner, and FIG. 1B is a cross-sectional view schematically showing in a further enlarged view a broken-line rectangular region in FIG. 1A. It is. In FIG. 1A, for example, an arrow having a length of 5 μm is described as a reference length indicating the size for reference. As shown in FIG. 1A and FIG. 1B, the RTB-based sintered magnet includes a main phase 12 mainly composed of an R ₂ T ₁₄ B compound, and a grain boundary phase 14 located at a grain boundary portion of the main phase 12. It consists of and. As shown in FIG. 1B, the grain boundary phase 14 includes two grain boundary phases 14a in which two R ₂ T ₁₄ B compound particles (grains) are adjacent, and grains in which three R ₂ T ₁₄ B compound particles are adjacent. Boundary triple point 14b.

The R ₂ T ₁₄ B compound that 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 may be close to 2: 14: 1).

The present inventor can modify the grain boundary phase and increase _HcJ by diffusing at least one selected from the group consisting of Ga, Cu, In, Al, Sn, and Co into the grain boundary. I found out that For such modification of the grain boundary phase, an R1-T-B system sintered magnet material (R1 is a rare earth element including at least one of Nd and Pr) is prepared, and R1-T-B system sintering is performed. It is preferable that the metal element M (at least one selected from the group consisting of Ga, Cu, In, Al, Sn, and Co) is supplied from the surface of the magnet material to the grain boundary to diffuse in the grain boundary. Such diffusion of the metal element M is an alloy of 65 mass% to 97 mass% R2 (rare earth element including at least one of Nd and Pr) and 3 mass% to 35 mass% M, that is, R2 -M alloy powder can be used. 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 investigation, the inventor applied R2-M alloy powder (atomized powder of R2-M alloy) produced by the atomizing method to the surface of the R1-T-B system sintered magnet material for diffusion. It has been found that when heat treatment is performed, the insulating member can be used as an excellent fusing agent for joining the R1-T-B sintered magnet material. That is, the atomized powder of the R2-M alloy functions as a diffusion source for introduction into the two-particle grain boundary of the R1-T-B system sintered magnet material, and insulates the R1-T-B system sintered magnet material. It has been found that it can also function as a powder that is bonded to a member and bonded uniformly. This is due to the uniform shape and size distribution of the atomized powder particles compared to the powder particles formed by pulverizing the R2-M alloy. As a result, it becomes difficult to form a nest on the joint surface, and the joint strength is improved.

  When the R1-T-B system sintered magnet material is joined to the insulating member, the strength of the R1-T-B system sintered magnet material itself can be supplemented with the assistance of the insulating member, and the overall strength and rigidity can be increased. . This exhibits an excellent effect especially when the thickness of the R1-T-B based sintered magnet material is thin. By bonding an R1-T-B sintered magnet material to an insulating member, for example, even when it has a sheet-like or bar-like shape with a thickness of 3 mm or less, an R-T-B based firing that hardly causes cracking or chipping. A magnetized magnet is realized.

  Further, when an R-T-B system sintered magnet is used in a motor, if a large eddy current is generated, power loss and unnecessary heat generation are caused. It is also possible to suppress the formation of eddy currents by laminating R1-T-B based sintered magnet materials via insulating members. Three or more R1-T-B-based sintered magnet materials may be laminated via an insulating member.

  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 strip casting method and then pulverized). The alloy powder is disposed between the two solid members 20 and is located in a gap formed by the opposing surfaces (surfaces to be joined) 20S of the members 20. As can be seen from FIG. 2, the shapes and sizes of the individual powder particles 50P are scattered. Since the alloy powder 50 is produced by pulverizing the alloy, the particles 50P have flat portions, acute-angle convex portions, complicated fracture surfaces, and the like.

  On the other hand, FIG. 3 is a schematic cross-sectional view of an R2-M alloy powder 30 formed by an atomization method according to an embodiment of the present disclosure. As FIG. 3 shows, each particle | grain 30P which comprises the R2-M alloy powder 30 formed by the atomizing method is spherical. Such spherical powder particles 30P are arranged between the surfaces (surfaces to be joined) 20S of the opposing solid member 20, and when the surfaces 20S of the solid member 20 are brought close to each other, the voids created by the opposing surfaces 20S are uniform. Can be rearranged to fill. For this reason, it is possible to increase the degree of adhesion of the bonding surface 20S without forming an unnecessary nest at the time of bonding.

  FIG. 4 is a perspective view schematically showing a state before joining of the R1-T-B system sintered magnet material according to the embodiment of the present disclosure. In the illustrated example, R1-T-B based sintered magnet materials 22 and 26 and insulating members 20 and 24 are alternately stacked. A layer of R2-M alloy powder 30 formed by an atomization method is formed between the first insulating member 20 located at the lower end and the first R1-T-B system sintered magnet material 22. . In the example of FIG. 4, the R2-M alloy powder 30 is applied to the upper surface of the first insulating member 20. However, the R2-M alloy powder 30 formed by the atomizing method may be applied to the bottom surface of the first R1-T-B system sintered magnet material 22. Similarly, the R2-M alloy powder 30 formed by the atomization method is also formed between the first R1-T-B-based sintered magnet material 22 and the second insulating member 24 positioned thereon. Layer is formed. Further, a layer of R2-M alloy powder 30 formed by the atomization method is also formed between the second insulating member 24 and the second R1-T-B sintered magnet material 26 located at the upper end. Has been. The R2-M alloy powder 30 includes a first R1-T-B based sintered magnet material 22, a second R1-T-B based sintered magnet material 25, a first insulating member 20, and a second insulating material. 24 may be applied to the entire surface.

  FIG. 5 is a perspective view schematically showing a state during joining of the R1-T-B based sintered magnet material according to the embodiment of the present disclosure. In the state shown in FIG. 5, the first insulating member 20 and the first R1-T-B system sintered magnet material 22 are close to each other with the R2-M alloy powder 30 interposed therebetween. The first R1-T-B system sintered magnet material 22 and the second insulating member 24 are close to each other with the R2-M alloy powder 30 interposed therebetween. The second insulating member 24 and the second R1-T-B 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 insulating member 20, the first R1-T-B system sintered magnet material 22, and the second insulating member 24. , And the second R1-T-B system sintered magnet material 26 are joined together to produce an R-T-B system sintered magnet 200 in which they are integrated.

  In this joining step, the rare earth element R2 and the metal element M contained in the R2-M alloy powder 30 are separated from the joining surfaces of the first and second R1-T-B based sintered magnet materials 22, 26. It diffuses inside the first and second R1-T-B system sintered magnet materials 22 and 26 through the boundary. 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 an improvement in bonding strength.

  Note that R2-M alloys such as Pr-Ga alloys have high ductility and generally poor grindability. For this reason, a long time is required for pulverization, and there is a problem in mass productivity. In the embodiment of the present disclosure, it is possible to obtain powder particles (for example, particles having a particle size of 200 μm or less) without performing pulverization by using atomized powder of R2-M alloy.

  As illustrated in FIG. 6, the manufacturing method of the RTB-based sintered magnet according to the present disclosure is prepared by the step S <b> 10 of preparing the R1-TB-based sintered magnet material and the insulating member, and the atomizing method. Step S20 of preparing the R2-M alloy powder. The order of the step S10 for preparing the R1-T-B based sintered magnet material and the insulating member and the step S20 for preparing the R2-M alloy powder produced by the R atomizing method is arbitrary, and each is manufactured at a different place. R1-T-B sintered magnet material, insulating member, and R2-M alloy atomized powder may be used.

  Furthermore, the manufacturing method of the R-T-B system sintered magnet by this indication WHEREIN: Process S30 which arrange | positions R2-M alloy powder between a R1-T-B system sintered magnet raw material and an insulating member, R1-T -The process S40 which joins a B type sintered magnet raw material and an insulating member is included.

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

1. Step of preparing R1-T-B system sintered magnet material First, an R1-T-B system sintered magnet material is prepared. The R1-T-B system sintered magnet material may be any known R-T-B system sintered magnet. A typical example of the R1-T-B system sintered magnet material that can be used in the present embodiment has the following composition.
Rare earth element R1: 27.5-35.0 mass%
B (a part of B (boron) may be substituted with C (carbon)): 0.80 to 0.99% by mass
Ga: 0 to 0.8 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 composed of Fe and may contain Co) and inevitable impurities: remainder

Also preferably, the following inequality (1) is satisfied.
[T] /55.85> 14 [B] /10.8 (1)
Here, [T] is the content of T expressed in mass%, and [B] is the content of B expressed in 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 do.

  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 heavy rare earth elements 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 entire R1-T-B based sintered magnet material, and most preferably, the R1-T-B based sintered magnet material is Dy. And does not contain heavy rare earth elements such as Tb (including unavoidable impurities).

  The R1-T-B based sintered magnet material having the above composition can be manufactured by any known manufacturing method. The R1-T-B based sintered magnet material may be sintered, or may be subjected to cutting or polishing.

  In the example shown in FIG. 4, the sizes of the insulating member 24 and the R1-T-B system sintered magnet material 26 are arbitrary. When the thickness of the R1-T-B system sintered magnet material 26 is 1 mm or less, the strength of the R1-T-B system sintered magnet material 26 itself is lowered, so that handling may generally be difficult. Even in such a case, according to the embodiment of the present disclosure, the insulating member 24 supports the R1-T-B system sintered magnet material 26 and the overall strength is improved, so that handling becomes easy. From such a viewpoint, the size of the R1-T-B based sintered magnet material 26 is, for example, not less than 0.5 mm and not more than 2 mm, and may be, for example, not less than 0.5 mm and not more than 1 mm.

2. Step of Preparing Insulating Member The insulating member is preferably formed from a material having a high withstand voltage. Yes. The insulating member needs to have heat resistance that can withstand the temperature at which the R2-M alloy powder melts. For this reason, the insulating member may be formed from a sheet of an inorganic material such as ceramics. For example, a sheet formed from mica. When the insulating member has a sheet shape, the thickness can be, for example, 0.01 mm or more and 1 mm or less.

3. Step of preparing R2-M alloy powder produced by atomization 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 entire 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 entire 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 (including unavoidable impurities). R2 is 65 mass% or more and 97 mass% or less of the whole R2-M alloy. R2 preferably contains Pr, and the amount of Pr in R2 is preferably 40% by mass or more, and 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 mass% or more and 35 mass% or less of the whole R2-M alloy. M preferably necessarily contains Ga, and the amount of Ga in M is 50% by mass or more. The R2-M alloy may contain inevitable impurities. Most preferably, an R2-M alloy powder is used in which the amount of Pr in R2 is 70% by mass or more and the amount of Ga in M is 50% by mass or more. Thereby, Ga can be introduced into the two-grain grain boundary with almost no introduction into the main phase crystal grains. By introducing a liquid phase containing Ga into the two-particle grain boundary, high _HcJ can be obtained without using Dy or Tb.

  In the embodiment of the present disclosure, the R2-M alloy powder is produced by an atomizing method. The atomizing method is a kind of powder preparation method called a 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 an alloy is melted in a melting furnace to form a molten metal, and the molten metal is sprayed and solidified in an inert gas atmosphere such as nitrogen or argon. Since the sprayed molten metal scatters as fine droplets, it is cooled and solidified at a high speed. Since the produced powder particles each have a spherical shape, it is not necessary to perform pulverization. The size of the powder particles produced by the atomizing method is distributed in the range of 10 μm to 200 μm, for example.

  According to the atomizing method, since the droplets of the molten alloy to be sprayed are small and the surface area relative to the weight of each droplet is relatively large, the cooling rate is increased. Therefore, the formed powder particles are amorphous or microcrystalline. Note that these powder particles may be additionally heat-treated before the bonding step to crystallize amorphous.

  The particle size of the R2-M alloy powder can be adjusted by sieving. In addition, if the amount of powder excluded by sieving is within 10% by mass, the influence is small, and it may be used without sieving.

4). Step of placing R2-M alloy powder between R1-T-B sintered magnet material and insulating member R2-M alloy powder is placed between R1-T-B sintered magnet material and insulating member (In other words, the R2-M alloy powder is sandwiched between the R1-T-B sintered magnet material and the insulating member). The arrangement method may be arranged by applying R2-M alloy powder to the surface of both the R1-T-B system sintered magnet material and the insulating member, or either one (R1-T-B system firing). The R2-M alloy powder may be simply applied to only the surface of the magnet material and the surface of the insulating member. Further, the R2-M alloy powder may be applied to the entire surface of at least one of the R1-T-B based sintered magnet material and the insulating member, or only the bonding surface as shown in FIG. Two or more types of R2-M alloy powders having different compositions may be used. The method of applying the R2-M alloy powder 30 to the surface of the insulating member and / or the R1-T-B system sintered magnet material is not limited to a specific application method. You may perform the application | coating process which apply | coats an adhesive to the surface of application | coating object, and the process of making R2-M alloy powder adhere to the area | region which applied the adhesive. Examples of the pressure-sensitive adhesive include PVA (polyvinyl alcohol), PVB (polyvinyl butyral), and PVP (polyvinyl pyrrolidone). In the case where the pressure-sensitive adhesive is a water-based pressure-sensitive adhesive, the RTB-based sintered magnet material may be preliminarily heated before application. The purpose of the preheating is to remove excess solvent and control the adhesive force, and to uniformly adhere the adhesive. The heating temperature is preferably 60 to 100 ° C. In the case of a highly volatile organic solvent-based pressure-sensitive adhesive, this step may be omitted.

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

5. The step of joining the R1-T-B system sintered magnet material and the insulating member According to the present disclosure, the R1-T-B system sintered magnet material and the R2-M alloy powder (atomized powder) are in contact with each other. Then, heat treatment for bonding is started. 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 bonding can be performed at a temperature of 450 ° C. or more and 1000 ° C. or less for a time of 5 minutes or more and 720 minutes or less. The heat treatment may be performed at a relatively low temperature (450 ° C. or more and 600 ° C. or less) after performing the heat treatment at a relatively high temperature (700 ° C. or more and 1000 ° C. or less). Preferred conditions are as follows: heat treatment at 730 ° C. or higher and 980 ° C. or lower for 5 to 500 minutes, cooling (cooling to room temperature or cooling to 440 ° C. or higher and 550 ° C. or lower), and further 440 ° C. or higher and 550 ° C. or lower 5 Heat treatment for about 500 minutes to 500 minutes. The atmosphere gas for the heat treatment can be nitrogen or an inert gas. The atmospheric gas may be decompressed.

  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-T-B sintered magnet material is approximately No. 1 in Table 1. Each element was weighed so as to have the composition shown in 1-A and cast by a strip casting method to obtain a flaky alloy. The obtained flaky alloy was hydrogen embrittled in a hydrogen-pressurized atmosphere, and then subjected to a dehydrogenation treatment in which it was heated and cooled in vacuum to 550 ° C. to obtain coarsely pulverized powder. Next, after adding and mixing 0.04% by mass of zinc stearate as a lubricant with respect to 100% by mass of the coarsely pulverized powder, the resulting coarsely pulverized powder was mixed with an airflow pulverizer (jet mill device). It was dry milled in a nitrogen atmosphere, the particle diameter _{D 50} was obtained alloy powder of 4.3 [mu] m. A liquid lubricant was added to and mixed with the alloy powder in an amount of 0.3% by mass with respect to 100% by mass of finely pulverized powder, and then molded in a magnetic field to obtain a molded body. The forming apparatus used was a so-called right-angle magnetic field forming apparatus (transverse magnetic field forming apparatus) in which the magnetic field application direction and the pressing method direction were orthogonal. The obtained molded body was sintered in vacuum at 1020 ° C. for 4 hours to prepare a plurality of R1-TB-based sintered magnet materials (No. 1-A). 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 so as to have a length of 10 mm × width of 5 mm (width is a magnetization direction) × thickness of 3 mm (thickness is a direction perpendicular to the magnetization). The results of the components of the obtained R1-T-B sintered magnet material are shown in Table 1. In addition, each component in Table 1 was measured using high frequency inductively coupled plasma optical emission spectrometry (ICP-OES). Moreover, all of the R1-T-B based sintered magnet materials satisfied the inequality (1). In addition, a ceramic insulating member was prepared. The dimensions of the insulating member were machined in the same manner as the R1-T-B system sintered magnet material to make the length 10 mm × width 5 mm × thickness 0.5 mm.

Next, no. An R1-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. 2 in Table 2 Each element was weighed so as to be an alloy having the composition shown in 1-b and cast by a strip casting method to obtain a flaky alloy. The obtained flaky alloy was hydrogen embrittled in a hydrogen-pressurized atmosphere, and then subjected to a dehydrogenation treatment in which it was heated and cooled in vacuum to 550 ° C. to obtain coarsely pulverized powder. After adding and mixing 0.04% by mass of zinc stearate as a lubricant with respect to 100% by mass of the coarsely pulverized powder, the resulting coarsely pulverized powder is mixed with a nitrogen atmosphere using an airflow pulverizer (jet mill device). dry milled at medium particle size _{D 50} was obtained alloy powder of 4.3 [mu] m.

  Next, no. An adhesive was applied to the entire surface of the 1-A R1-T-B system sintered magnet material surface. The application method was as follows. The R1-T-B system sintered magnet material was heated to 60 ° C. on a hot plate, and then an adhesive was applied to the R1-T-B system sintered magnet material by a spray method. PVP (polyvinyl pyrrolidone) was used as an adhesive.

  Next, with respect to the R1-T-B sintered magnet material (No. 1-A) coated with an adhesive, No. 1 in Table 2 was obtained. A 1-a diffusion source (R2-M alloy powder) was deposited. The adhesion method is to spread the diffusion source on the container, lower the temperature of the R1-T-B system sintered magnet material coated with adhesive to room temperature, and then use the R1-T-B system sintered magnet material in the container. It was made to adhere to the whole surface.

  Next, the R1-T-B system sintered magnet material (No. 1-A) and the R2-M alloy powder (No. 1-a) are in contact with each other, and the R1-T-B system sintered magnet material. No. 1-A and an insulating member are stacked in a thickness (3 mm) direction (surfaces of 10 mm length × 5 mm width are brought into contact with each other) and bonded by heat treatment to obtain an R-T-B system sintered magnet (No. 1-1) was obtained. The heat treatment was performed 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, for the R1-T-B sintered magnet material (No. 1-A), No. 1 in Table 2 was obtained. A 1-b diffusion source was attached and bonded by heat treatment in the same manner to obtain an RTB-based sintered magnet (No. 1-2).

  The generation of nests on the joint surface of the obtained RTB-based sintered magnet was confirmed. If a large number of nests are generated, the adhesive strength may decrease or peeling may occur starting from the nests. Therefore, an R-T-B system sintered magnet is used for a motor that needs to rotate at a high speed. If possible, it is necessary to suppress the occurrence of nests.

  R-T-B system sintered magnets (No. 1-1 and 1-2) are cut and polished by machining, respectively, and a cross section (magnet cross section at a width of 5 mm × thickness of 6 mm) of an arbitrary bonded magnet including a bonded surface is shown. It observed with the scanning electron microscope (SEM: JEOL JCM-7001F). The observation area was 500 μm × 500 μm, and the occurrence of nests on the joint surface was confirmed by visual recognition. Nest generation is 20% or less of the joint surface (100 × nest area / joint area). The results are shown in Table 3. The case where the occurrence of the nest is 20% or less is described as ◯ and the case where the nest is 20% or more is described as x. Further, Table 3 shows the results of the magnetic characteristics of the R-T-B system sintered magnet. The magnetic characteristics were measured by cutting only the R1-T-B system sintered magnet material from the bonded R-T-B system sintered magnet by cutting and using a B-H tracer.

  As shown in Table 3, nest formation is suppressed in the inventive examples, whereas nest generation is not suppressed in the comparative example (using a diffusion source produced by a strip cast method).

Experimental example 2
No. in Table 4 An R1-T-B system sintered magnet material was prepared in the same manner as in Experimental Example 1 so that the compositions shown in 2-A and 2-B were obtained. The obtained R1-T-B based sintered magnet material was machined to have a length of 10 mm, a width of 5 mm, and a thickness of 3 mm (the direction in which the thickness is perpendicular to the magnetization). Table 4 shows the results of the components of the obtained R1-T-B sintered magnet material. In addition, each component in Table 4 was measured using the high frequency inductively coupled plasma optical emission spectroscopy (ICP-OES). In addition, a ceramic insulating member was prepared. The dimensions of the insulating member were machined in the same manner as the R1-T-B system sintered magnet material to make the length 10 mm × width 5 mm × thickness 0.5 mm. Next, in the same manner as in Example 1, no. 1-a R2-M alloy powder was prepared.

  Next, under the conditions shown in Table 6, the R1-T-B system sintered magnet material and the insulating member were joined in the same manner as in Experimental Example 1 to obtain an R-T-B system sintered magnet. No. in Table 6 2-1. An adhesive was applied to the entire surface of the 2-A R1-T-B system sintered magnet material in the same manner as in Experimental Example 1, and an R1-T-B system sintered magnet material (No. 2- In contrast to A), no. 1-a R-2M alloy powder was deposited in the same manner as in Experimental Example 1. Next, the R1-T-B system sintered magnet material (No. 2-A) and the R2-M alloy powder (No. 1-a) are in contact with each other, and the R1-T-B system sintered magnet material. No. 2-A and the insulating member are stacked in the thickness direction (3 mm), and bonded by performing heat treatment in the same manner as in Experimental Example 1 to obtain an RTB-based sintered magnet (No. 2-1) It is a thing. No. 2-2 is similarly described. With respect to the obtained RTB-based sintered magnet, generation of nests on the joint surface was confirmed by visual recognition in the same manner as in Experimental Example 1.

  As shown in Table 6, the nests of all the inventive examples are 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 a motor for mounting on a hybrid vehicle exposed to high temperatures, home appliances, and the like.

12 R ₂ T ₁₄ B main phase composed of compound 14 grain boundary phase 14 a two grain grain boundary phase 14 b grain boundary triple point 20, 24 solid member 22, 26 R 1 -T-B system sintered magnet material 30 R 2 -M alloy powder 50 alloy powder

Claims (7)

Step of preparing an R1-T-B based sintered magnet material (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) When,
Preparing an insulating member;
R2: 65 mass% or more and 97 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 entire R2 is 50 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)
A step of preparing an R2-M alloy powder prepared by an atomizing method,
The R2-T-B system sintered magnet material is disposed between the R1-T-B system sintered magnet material and the insulating member, and the R1-T-B system sintered magnet material is used at a temperature of 450 ° C. or higher and 1000 ° C. or lower. Bonding the insulating member;
The manufacturing method of the RTB type | system | group sintered magnet including this.   The manufacturing method of the RTB type | system | group sintered magnet of Claim 1 whose sum total content of Dy and Tb with respect to the whole R2 is 15 mass% or less.   The method for producing an R-T-B system sintered magnet according to claim 1 or 2, wherein R2 necessarily contains Pr and M necessarily contains Ga.   The said insulating member is a manufacturing method of the RTB system sintered magnet in any one of Claim 1 to 3 which is a sheet | seat formed from the mica.   The method for producing an RTB-based sintered magnet according to any one of claims 1 to 4, wherein the R1-TB-based sintered magnet material has an average thickness of 2 mm or less.   The said R1-T-B system sintered magnet raw material is a manufacturing method of the RTB system sintered magnet in any one of Claim 1 to 5 which has an average thickness of 1 mm or less.   The R-T-B system firing according to any one of claims 1 to 6, wherein the joining step includes a step of laminating three or more R1-T-B system sintered magnet materials via the insulating member. A manufacturing method of a magnet.

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