JP2017183348A - Method for manufacturing r-t-b-based sintered magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an R-T-B-based sintered magnet, in which a heavy rare earth element RH is diffused from the surface of an R-T-B-based sintered magnet material thereinto.SOLUTION: A method for manufacturing an R-T-B-based sintered magnet comprises the steps of: preparing an R-T-B-based sintered magnet material; preparing alloy powder particles of 90 μm or less in size, which include 20-80 mass% of a heavy rare earth element RH; and preparing stirring auxiliary members of which the respective diameters are in a range of 0.5-4 mm. The method further comprises the steps of: feeding the R-T-B-based sintered magnet material, 2-15% of alloy powder particles to a weight of the R-T-B-based sintered magnet material, and 100-500% of the stirring auxiliary members to the weight of the R-T-B-based sintered magnet material into a process chamber; and rotating and/or swinging the process chamber while heating the process chamber, thereby continuously or intermittently moving the R-T-B-based sintered magnet material, the alloy powder particles and the stirring auxiliary members to perform an RH supply diffusion process.SELECTED DRAWING: Figure 2

Description

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

  The RTB-based sintered magnet is known as the highest performance magnet among permanent magnets. Here, R is at least one kind of rare earth elements and always contains at least one of Nd and Pr. T is at least one of transition metal elements and necessarily contains Fe. R-T-B sintered magnets are a wide variety of motors such as voice coil motors (VCM) for hard disk drives, motors for electric vehicles (including EV, HV, PHV), motors for industrial equipment, and home appliances. It is used for various purposes.

The RTB-based sintered magnet is composed of a main phase made of a compound having an R ₂ T ₁₄ B-type crystal structure and a grain boundary phase located at the grain boundary portion of the main phase. The main phase R ₂ T ₁₄ B phase is a ferromagnetic phase and mainly contributes to the magnetizing action of the R—T—B system sintered magnet.

In the RTB-based sintered magnet, a part of the light rare earth element RL (mainly Nd and / or Pr) contained in R in the main phase R ₂ T ₁₄ B phase is converted to heavy rare earth element RH (mainly Dy And / or Tb) is known to improve the coercive force H _cJ (hereinafter sometimes simply referred to as “H _cJ ”). That is, in order to improve H _cJ , it is necessary to use a large amount of heavy rare earth element RH.

However, when the light rare earth element RL in the R ₂ T ₁₄ B phase is replaced with the heavy rare earth element RH in the R-T-B based sintered magnet, H _cJ is improved, while the residual magnetic flux density B _r (hereinafter simply “ “B _r ” may decrease). Therefore, to improve the H _cJ are sought without reducing the B _r with the use of RH less heavy rare-earth element. Further, since the heavy rare earth element RH is a rare metal, a reduction in the amount of use is required.

In recent years, for the purpose of improving _HcJ of an R-T-B type sintered magnet, heavy rare earth elements RH such as Dy and Tb are supplied to the surface of the R-T-B type sintered magnet, and the heavy rare earth element RH is used as a magnet. while suppressing the decrease in B _r by diffusing into the interior, a method of improving the H _cJ is proposed.

  In Patent Document 1, the sintered body and the bulk body containing the heavy rare earth element RH are arranged apart from each other through a Nb net or the like, and the sintered body and the bulk body are heated to a predetermined temperature. A method is described in which heavy rare earth elements RH are supplied from the bulk body to the surface of the sintered body and diffused into the sintered body.

  In Patent Document 2, a powder containing at least one of Dy and Tb is heated at a temperature lower than the sintering temperature in a state where the powder is present on the surface of the sintered body, whereby at least one of Dy and Tb is obtained from the powder. A method of diffusing into the sintered body is described.

  Patent Document 3 discloses that a plurality of RTB-based sintered magnet bodies and a plurality of RH diffusion sources containing heavy rare earth elements RH are relatively movable and close to or in contact with each other. The R—T—B-based sintered magnet body and the RH diffusion source are heated while being moved continuously or intermittently in the processing chamber, whereby the heavy rare earth element is removed from the RH diffusion source. A method is described in which RH is supplied to the surface of the RTB-based sintered magnet body and diffused into the sintered body.

International Publication No. 2007/102391 International Publication No. 2006/043348 International Publication No. 2011/007758

While suppressing the decrease in B _r by the method described in Patent Documents 1 to 3, it is possible to improve the H _cJ. However, since the method described in Patent Document 1 requires the sintered body and the bulk body containing the heavy rare earth element RH to be spaced apart from each other, it takes time to place the sintered body. In addition, the method described in Patent Document 2 takes time and effort to apply a slurry in which a powder containing Dy or Tb is dispersed in a solvent to a sintered body. On the other hand, in the method described in Patent Document 3, the RH diffusion source and the RTB-based sintered magnet body are charged into the processing chamber and moved continuously or intermittently. Specifically, the processing container is rotated and / or rocked. Therefore, it is not necessary to arrange the R-T-B system sintered magnet body and the RH diffusion source apart from each other, and it is also necessary to disperse in the solvent or to apply the slurry dispersed in the solvent to the sintered body. Absent. According to the method of Patent Document 3, the heavy rare earth element RH can be diffused into the sintered body while being supplied to the RTB-based sintered magnet body from the RH diffusion source.

According to the method described in Patent Document 3, a relatively simple manner, while suppressing the decrease in B _r, although it is possible to improve the H _cJ, increased width of the H _cJ varies, high stable H _cJ May not be obtained.

  In addition, as an RTB-based sintered magnet exhibiting a high coercive force, those having various shapes than before have been demanded. For example, there is a demand for a RTB-based sintered magnet having a shape extending long in one direction and having a size of 5 mm long × 5 mm wide × 50 mm long. When the technique described in Patent Document 3 is applied to the material of the RTB-based sintered magnet having such an anisotropic shape, the RTB-based sintered magnet material It was found that some cracks and chips may occur.

  The present disclosure provides a new method for producing an RTB-based sintered magnet.

  The manufacturing method of the RTB-based sintered magnet of the present disclosure is, in one embodiment, a plurality of RTB-based sintered magnet materials (where R is at least one kind of rare earth elements, and Nd and Pr). A step of preparing at least one, T is at least one of transition metal elements and must contain Fe), and a heavy rare earth element RH (heavy rare earth element RH is at least one of Tb and Dy) of 20% by mass or more A step of preparing a plurality of alloy powder particles having a size of 90 μm or less, containing 80% by mass or less, and a plurality of stirring auxiliary members, 65% of the total of the plurality of stirring auxiliary members by weight ratio A step of preparing a stirring auxiliary member having a diameter of 0.5 mm or more and 4 mm or less, the plurality of RTB-based sintered magnet materials, and the plurality of RTBs. For sintered magnet materials The alloy powder particles having a weight ratio of 2% to 15%, and the stirring auxiliary member having a weight ratio of 100% to 500% with respect to the plurality of R-T-B sintered magnet materials, The RTB-based sintered magnet material, the alloy powder particles, and the stirring auxiliary member by heating and rotating and / or swinging the processing container. And a process of performing RH supply diffusion processing by moving continuously or intermittently.

  In one embodiment, in the step of performing the RH supply diffusion treatment, the treatment container is heated to a treatment temperature of 800 ° C. or higher and 1000 ° C. or lower.

  In one embodiment, each of the plurality of alloy powder particles has a size of 38 μm or more and 75 μm or less.

  In one embodiment, a weight ratio of the plurality of alloy powder particles charged into the processing container to the RTB-based sintered magnet material is 3% or more and 7% or less.

  In one embodiment, the plurality of alloy powder particles contain alloy powder particles in which a new surface is exposed at least partially.

  In one embodiment, the plurality of alloy powder particles contain the heavy rare earth element RH in an amount of 35 mass% to 65 mass%.

  In one embodiment, the heavy rare earth element RH is Tb.

In one embodiment, the plurality of RTB-based sintered magnet materials have a volume of 1000 mm ³ or more, and a maximum size of three sizes in three orthogonal directions is twice or more a minimum size. It is.

  In one embodiment, each of the plurality of sintered magnet materials is chamfered in a rectangular parallelepiped shape having a length of one side of 40 mm or more and a length of the other two sides of 10 mm or less, or at each vertex position. It has a substantially rectangular parallelepiped shape.

  In one embodiment, each of the plurality of stirring assisting members is made of ceramics of zirconia, silicon nitride, silicon carbide, boron nitride, or a mixture thereof.

  In one embodiment, the RTB-based sintered magnet material supplied with the heavy rare earth element RH from any one of the plurality of alloy powder particles in the RH supply diffusion treatment step is used as the alloy powder particles. And a step of performing RH diffusion treatment by heating in a non-contact state.

  In one embodiment, the plurality of alloy powder particles are produced by hydrogen pulverizing an alloy containing a heavy rare earth element RH (heavy rare earth element RH is Tb and / or Dy) in a range of 35 mass% to 50 mass%. In the dehydrogenation step in the hydrogen pulverization, the alloy is heated to 400 ° C. or higher and 550 ° C. or lower.

According to the embodiment of the present disclosure, high H _cJ can be _stably obtained. Moreover, even if the RTB-based sintered magnet material has a shape that is easily chipped, an effect of reducing the occurrence of cracks and chips can be obtained.

(A) And (b) is a perspective view which shows the example of the shape of a sintered magnet raw material. It is sectional drawing which shows typically an example of the apparatus used for RH supply diffusion process of this invention. It is a graph which shows an example of the heat pattern at the time of a diffusion process process.

As a result of the examination by the present invention, according to the method described in Patent Document 3, if the individual RH diffusion sources are too large or there are many small RH diffusion sources, the R-T-B system sintered magnet can be obtained. It has been found that the supply of heavy rare earth element RH becomes insufficient and high H _cJ may not be obtained.

In addition, the size of the RH diffusion source containing the heavy rare earth element RH in the range of 20% by mass to 80% by mass is limited to 90 μm or less, and the weight ratio of the RH diffusion source inserted into the processing vessel is within an appropriate range. By adjusting and using an auxiliary stirring member having a diameter of 0.5 mm or more and 4 mm or less, a stable high H _cJ can be obtained, and the R-T-B system sintered magnet material is easily chipped. Even if it has, it turned out that the effect of reducing generation | occurrence | production of a crack and a chip | tip is also acquired.

  In a non-limiting exemplary embodiment, the manufacturing method of the RTB-based sintered magnet of the present disclosure includes a step of preparing a plurality of RTB-based sintered magnet materials, and a heavy rare earth element RH. Preparing a plurality of alloy powder particles having a size of 90 μm or less, and a plurality of stirring auxiliary members each having a diameter in the range of 0.5 mm to 4 mm And preparing a process.

  Here, R is at least one of rare earth elements and always includes at least one of Nd and Pr, and T is at least one of transition metal elements and always includes Fe. The heavy rare earth element RH is at least one of Tb and Dy. In addition, the stirring auxiliary member which occupies 65% or more of the whole stirring auxiliary member by weight ratio has a diameter of 0.5 mm or more and 4 mm or less, respectively. The diameter of each of the stirring assisting members occupying 65% or more of the entire stirring assisting member by weight ratio may be 1 mm or more and 3 mm or less in some embodiments, and may be 2 mm or more and 3 mm or less in other embodiments.

  The manufacturing method of the RTB-based sintered magnet of the present disclosure is not limited to the exemplary embodiment, and further includes the plurality of RTB-based sintered magnet materials and the plurality of R-based sintered magnet materials. -The alloy powder particles having a weight ratio of 2% to 15% with respect to the TB sintered magnet material, and 100% with respect to the plurality of RTB sintered magnet materials. The step of charging the stirring auxiliary member of 500% or less into the processing container, and heating and rotating and / or swinging the processing container, thereby allowing the RTB-based sintered magnet material and the alloy powder to be heated. And a step of performing the RH supply diffusion process by moving the particles and the stirring auxiliary member continuously or intermittently.

  In the step of performing the RH supply diffusion treatment, each alloy powder particle containing the heavy rare earth element RH at 20% by mass or more and 80% by mass or less functions as an RH diffusion source. When the processing container is rotating and / or swinging, the RTB-based sintered magnet material and the alloy powder particles are agitated in the heated processing container, and come into contact with each other or leave after the contact. Repeat that. At this time, since the stirring auxiliary member promotes stirring of the RTB-based sintered magnet material and the alloy powder particles, the RTB-based sintered magnet material, the alloy powder particles, and the stirring auxiliary member are: It moves and moves in the processing container. The weight ratio of the stirring assisting member charged in the processing vessel to the R-T-B type sintered magnet material charged in the processing vessel may be 200% or more and 300% or less in a preferred embodiment. .

  In a preferred embodiment, the plurality of alloy powder particles are produced by hydrogen pulverizing an alloy containing a heavy rare earth element RH (heavy rare earth element RH is Tb and / or Dy) in a range of 35 mass% to 50 mass%, In the dehydrogenation step in the hydrogen pulverization, the alloy is heated to 400 ° C. or higher and 550 ° C. or lower.

In the method described in Patent Document 3, the size of the RH diffusion source is not particularly limited. Further, Patent Document 3 does not describe how much the RH diffusion source having a specific size is inserted into the RTB-based sintered magnet material. As a result of examining the method described in Patent Document 3 in detail, the present inventors have prepared alloy powder particles of a specific size as an RH diffusion source, and the alloy powder particles of the specific size are prepared. It has been found that a high H _cJ can be _stably obtained by _{setting the charging amount} to a specific ratio with respect to the weight ratio of the _RTB -based sintered magnet material.

  In the present disclosure, supplying the heavy rare earth element RH to the RTB-based sintered magnet material and diffusing the heavy rare earth element RH into the magnet is referred to as “RH supply diffusion treatment”. Moreover, after carrying out the RH supply diffusion treatment, diffusing the heavy rare earth element RH into the inside of the R-T-B system sintered magnet without supplying the heavy rare earth element RH is called “RH diffusion treatment”. Furthermore, the heat treatment performed for the purpose of improving the magnet characteristics of the RTB-based sintered magnet after the RH supply diffusion treatment or after the RH diffusion treatment is simply referred to as “heat treatment”.

[Step of preparing a plurality of RTB-based sintered magnet materials]
In an embodiment of the present invention, an R-T-B based sintered magnet material (R is at least one of rare earth elements and always includes at least one of Nd and Pr, T is at least one of transition metal elements and Fe R-T-B sintered magnet material manufactured by a known composition and manufacturing method can be used.

  In the present disclosure, the RTB-based sintered magnet before and during the RH supply diffusion process is referred to as an “RTB-based sintered magnet material”, and the RT after the RH supply diffusion process. -B system sintered magnet is called "RTB system sintered magnet."

The RTB-based sintered magnet material in the embodiment of the present disclosure has the following composition, for example.
Rare earth element R: 12-17 atom%
B (a part of B may be substituted with C): 5 to 8 atomic%
Additive element M (selected from the group consisting of Al, Ti, V, Cr, Mn, Ni, Cu, Zn, Ga, Zr, Nb, Mo, Ag, In, Sn, Hf, Ta, W, Pb, and Bi At least one): 0 to 2 atomic%
T (a transition metal mainly composed of Fe and may contain Co) and inevitable impurities: balance

  The RTB-based sintered magnet material having the above composition is manufactured by a known manufacturing method.

The plurality of sintered magnet materials that can be used in the embodiment of the present disclosure each have a volume of, for example, 1000 mm ³ or more, and the maximum size of three sizes in three orthogonal directions is twice the minimum size. That's it.

  FIG. 1 is a perspective view showing an example of the shape of the sintered magnet material 1. FIG. 1A shows the dimensions of the sintered magnet material 1, that is, the length L, the depth D, and the height H. FIG. 1B shows a form in which chamfering is performed on eight vertices of the sintered magnet material shown in FIG.

  In one embodiment, each of the plurality of sintered magnet materials has a rectangular parallelepiped shape in which the length (L) of one side is 40 mm or more and the lengths (D, H) of the other two sides are each 20 mm or less. doing. In another embodiment, each of the plurality of sintered magnet materials may have a substantially rectangular parallelepiped shape with one side having a length of 40 mm or more and the other two sides having a length of 10 mm or less. Each sintered magnet material may be chamfered at each vertex position as shown in FIG. By chamfering, the occurrence of cracks and chips can be further suppressed.

  The shape and size of the sintered magnet material to which the manufacturing method of the present disclosure is applied are not limited to the above example.

[Step of preparing a plurality of alloy powder particles]
In the present invention, as the RH diffusion source, a plurality of alloy powder particles having a size of 90 μm or less and containing 20 to 80% by mass of the heavy rare earth element RH are prepared. In the present invention, the heavy rare earth element RH is Tb and / or Dy. For example, a TbFe alloy, a DyFe alloy, or the like containing 20 mass% to 80 mass% of Tb and / or Dy can be used. Higher H _cJ can be obtained by using Tb than Dy. When the heavy rare earth element RH is less than 20% by mass, the supply amount of the heavy rare earth element RH is decreased, and high H _cJ may not be obtained. Further, if the heavy rare earth element RH exceeds 80% by mass, the RH diffusion source may ignite when the RH diffusion source is put into the processing container. The content of the heavy rare earth element RH in the RH diffusion source is preferably 35% by mass to 65% by mass, and more preferably 40% by mass to 60% by mass.

The method of preparing a plurality of alloy powder particles having a size of 90 μm or less in the embodiment of the present invention is not particularly limited. For example, classification can be performed using a sieve having a mesh opening of 90 μm (JIS Z 8801-2000 standard sieve). When alloy powder particles having a size of 90 μm or less are not used, high H _cJ cannot be stably obtained. For alloy powder particles having a size of 90 μm or less, an alloy containing heavy rare earth element RH of 20% by mass or more and 80% by mass or less is pulverized using a known method such as a pin mill pulverizer, and a sieve having an opening of 90 μm is used. It can prepare by classifying using.

  When a plurality of alloy powder particles having a size of 90 μm or less are prepared using a known method such as the pin mill pulverizer, it takes a long time to pulverize the alloy to 90 μm or less, or pin mill pulverization is performed several times. Doing so may lead to deterioration of mass productivity. Therefore, in place of these methods, hydrogen pulverization is performed, in which hydrogen is occluded in an alloy containing heavy rare earth element RH 35 mass% to 50 mass% and then heated to 400 ° C. or higher and 550 ° C. or lower. May be performed. As a result, almost all of the plurality of alloy powder particles (weight ratio of 90% or more) can be pulverized to a size of 90 μm or less, so that it is relatively simple and a large amount is 90 μm or less at a time. A plurality of alloy powder particles can be obtained. Accordingly, it is possible to perform the RH supply diffusion treatment by directly charging a plurality of alloy powder particles into the processing vessel without performing classification using a sieve having an opening of 90 μm. In this case, when a plurality of alloy powder particles are charged to the RTB-based sintered magnet material at 2%, which is the lower limit of the weight ratio, and RH supply diffusion treatment is performed, a plurality of particles having a size of 90 μm or less are obtained. Since the weight ratio of the individual alloy powder particles may be 2% or less, it is preferable to charge 2.2% or more by weight ratio.

  When performing the hydrogen pulverization, an alloy containing 35% by mass or more and 50% by mass or less of the heavy rare earth element RH is prepared. If the content of the heavy rare earth element RH is less than 35% by mass, the alloy may not be hydrogen crushed to a size of 90 μm or less. On the other hand, if the content of the heavy rare earth element RH exceeds 50% by mass, a large amount of hydrogen may remain. Therefore, the content of the heavy rare earth element RH is preferably 35% by mass or more and 50% by mass or less. Hydrogen crushing is performed on the alloy. Hydrogen pulverization is performed by temporarily storing hydrogen in the alloy and then releasing the hydrogen. Therefore, hydrogen pulverization includes a hydrogen storage process and a dehydrogenation process. What is necessary is just to perform the hydrogen storage process in the hydrogen pulverization of this invention by a well-known method. For example, after charging the alloy into the hydrogen furnace, hydrogen supply into the hydrogen furnace is started at room temperature, and a hydrogen occlusion process for maintaining the absolute pressure of hydrogen at about 0.3 MPa is performed for 90 minutes. In this step, the hydrogen in the furnace is consumed with the hydrogen occlusion reaction of the alloy powder, and the pressure of the hydrogen decreases. Therefore, hydrogen is additionally supplied to compensate for the decrease, and the pressure is controlled to about 0.3 MPa. In the dehydrogenation step, the alloy after the hydrogen storage step is heated to 400 ° C. or higher and 550 ° C. or lower in vacuum. Thereby, the size can be pulverized to 90 μm or less with almost no hydrogen remaining. When the heating temperature is less than 400 ° C. and exceeds 550 ° C., hydrogen remains (about several hundred ppm) in the plurality of alloy powder particles. When the hydrogen remains, hydrogen is supplied from the plurality of alloy powder particles to the RTB-based sintered magnet material during the subsequent RH supply diffusion treatment, and finally the RTB-based sintered magnet is obtained. Becomes hydrogen embrittled and cannot be used as a product. Therefore, the heating temperature in the dehydrogenation step is preferably 400 ° C. or higher and 550 ° C. or lower.

Preferably, the size of the alloy powder particles is 38 μm or more and 75 μm or less, and more preferably, the size of the alloy powder particles is 38 μm or more and 63 μm. _This is because high H _cJ can be obtained more stably. Moreover, when many alloy powder particles less than 38 micrometers are contained, since an alloy powder particle is too small, there exists a possibility that a RH diffusion source may ignite. The alloy powder particles may contain at least one of Nd, Pr, La, Ce, Zn, Zr, Sm, and Co as long as the effects of the present invention are not impaired other than Tb, Dy, and Fe. Furthermore, as inevitable impurities, Al, Ti, V, Cr, Mn, Ni, Cu, Ga, Nb, Mo, Ag, In, Hf, Ta, W, Pb, Si, and Bi may be included.

  It is preferable that the plurality of alloy powder particles contain alloy powder particles in which a new surface is exposed at least partially. In the present invention, the nascent surface is exposed when the surface of the alloy powder particle is a foreign substance other than the RH diffusion source, such as an R oxide or an R-T-B compound (compound having a composition close to the main phase). The state where does not exist. As described above, the plurality of alloy powder particles are prepared by pulverizing an alloy containing 20% by mass or more and 80% by mass or less of the heavy rare earth element RH. Therefore, the plurality of alloy powder particles obtained thereby are at least It has alloy powder particles in which the nascent surface is partially exposed. However, when the RH supply diffusion process is repeatedly performed, that is, in place of the R-T-B system sintered magnet after the RH supply diffusion process, a plurality of new RTB system sintered magnet materials are prepared. When the RH supply diffusion treatment is performed again using the plurality of R-T-B sintered magnet materials and the plurality of (used) alloy powder particles after the RH supply diffusion treatment, Even if a plurality of alloy powder particles having a size of 90 μm or less exist after the supply diffusion treatment, the entire surface of the alloy powder particles after the RH supply diffusion treatment is covered with foreign matters, R oxides, etc. The new surface may not be exposed. Therefore, when the RH supply diffusion treatment is repeatedly performed using the processed alloy powder particles, the supply of the heavy rare earth element RH to the RTB-based sintered magnet material is reduced due to foreign matter, R oxide, or the like. There is. Therefore, it is preferable to pulverize the processed alloy powder particles with a known pulverizer or the like so that the fracture surface of the alloy powder particles is exposed, that is, the nascent surface is exposed.

[Step of charging RTB-based sintered magnet material and alloy powder particles into processing vessel]
A plurality of R-T-B based sintered magnet materials, and a plurality of alloy powder particles having a weight ratio of 2% to 15% with respect to the plurality of R-T-B based sintered magnet materials; Is charged into the processing container. Thereby, high _HcJ can be stably obtained by performing the process of performing the RH supply diffusion process mentioned later. When a plurality of alloy powder particles having a size of 90 μm or less are less than 2% by weight with respect to the R-T-B sintered magnet material, since the alloy powder particles of 90 μm or less are too few, stable High H _cJ cannot be obtained. When the content exceeds 15%, the alloy powder particles react excessively with the liquid phase leached from the RTB-based sintered magnet material, and abnormally adhere to the surface of the RTB-based sintered magnet material. A phenomenon occurs. Due to this phenomenon, a state in which a new heavy rare earth element RH is difficult to be supplied to the R-T-B based sintered magnet material is formed, and thus high H _cJ cannot be stably obtained. For this reason, alloy powder particles of 90 μm or less are necessary to stably obtain high H _cJ , but the amount needs to be in a specific range (2% or more and 15% or less). Preferably, the charged amount of the plurality of alloy powder particles is 3% or more and 7% or less by weight with respect to the plurality of RTB-based sintered magnet materials. _This is because high H _cJ can be obtained more stably.

  If a plurality of alloy powder particles having a size of 90 μm or less are charged to 2% or more and 15% or less with respect to a plurality of RTB-based sintered magnet materials, that is, the embodiment of the present invention described above is used. In addition to these, for example, a plurality of alloy powder particles having a size exceeding 90 μm may be charged into the processing container. However, since the heavy rare earth element RH is a rare metal and a reduction in the amount of use is required, it is preferable not to use a plurality of alloy powder particles having a size exceeding 90 μm. Also, if there are too many alloy powder particles having a size exceeding 90 μm, the amount of RT-B system sintered magnet material that can be processed at one time will be reduced. The powder particles (the total of the alloy powder particles having a size of 90 μm or less and over 90 μm) are preferably charged into the processing container so that the weight ratio is 1: 0.02-2.

  In an embodiment of the present invention, a plurality of stirring assist members are further charged in the processing container. The agitation auxiliary member promotes contact between the alloy powder particles and the RTB-based sintered magnet material, and the heavy rare earth element RH once attached to the agitation auxiliary member is indirectly applied to the RTB-based sintered magnet material. The role to supply. Furthermore, the stirring assisting member also has a role of preventing chipping due to contact between the RTB-based sintered magnet materials in the processing container.

  In the embodiment of the present disclosure, there are a plurality of stirring assisting members, in which 65% or more of the stirring assisting members of the plurality of stirring assisting members is 0.5 mm to 4 mm in weight ratio. . The diameter φ of the stirring auxiliary member is preferably 1 mm or more and 3 mm or less, more preferably 2 mm or more and 3 mm or less. In addition, if the stirring auxiliary member satisfies the above-described conditions of the present invention (the stirring auxiliary member having a diameter of 0.5 mm or more and 4 mm or less is 65% or more), the stirring auxiliary member is less than 0.5 mm or exceeds 4 mm. You may have the stirring auxiliary member which has a diameter. However, if it is too large or too small, it may be difficult to handle in mass production. Therefore, the stirring assisting member preferably has a diameter of 0.3 mm or more and 20 mm or less.

  In order to fully exhibit the function of the stirring auxiliary member, the amount of the stirring auxiliary member charged in the processing vessel is 100 by weight with respect to the plurality of R-T-B system sintered magnet materials to be inserted. % Or more and 500% or less, preferably 200% or more and 300% or less.

  It is preferable that the stirring auxiliary member has a shape that can easily move in the processing container. Examples of shapes that are easy to move here include spherical and cylindrical shapes. The stirring assisting member is preferably formed of a material that does not easily react even when it contacts the RTB-based sintered magnet material and alloy powder particles during the RH supply diffusion treatment. As a material for the stirring auxiliary member, zirconia, silicon nitride, silicon carbide, boron nitride, ceramics of a mixture thereof, or the like is preferable. It may be a group element including Mo, W, Nb, Ta, Hf, Zr, or a mixture thereof.

[Step of performing RH supply diffusion treatment]
By heating and rotating and / or swinging the processing vessel charged with a plurality of R-T-B type sintered magnet materials and a plurality of alloy powder particles according to the above process, the R-T-B type While supplying the rare earth element RH from the alloy powder particles to the surface of the R-T-B system sintered magnet material by moving the sintered magnet material and the alloy powder particles continuously or intermittently, An RH supply diffusion process for diffusing the heavy rare earth element RH into the magnet is performed. Thus, while suppressing a decrease in B _r, it is possible to stably obtain a high H _cJ. The RH supply diffusion process of the present invention may be performed by a known method described in Patent Document 3. FIG. 2 is a cross-sectional view schematically showing an example of an apparatus used for the RH supply diffusion process of the present invention. A method of using the apparatus will be described with reference to FIG. First, the lid 5 shown in FIG. 2 is removed from the processing vessel 4, and a plurality of RTB-based sintered magnet materials 1, a plurality of alloy powder particles 2, and a plurality of stirring auxiliary members 3 are charged into the processing vessel 4. Then, the lid 5 is attached to the processing container 4 again. The proportions of the charged amounts of the RTB-based sintered magnet material 1, the alloy powder particles 2, and the stirring auxiliary member 3 are set so as to be within the predetermined range described above.

  Next, the inside of the processing container 4 is evacuated and decompressed by the exhaust device 6 (Ar gas or the like may be introduced after decompression). Then, heating by the heater 7 is performed while rotating the processing container 4 by the motor 8. By rotating the processing container 4, the RTB-based sintered magnet material 1, the alloy powder particles 2, and the stirring auxiliary member 3 are uniformly stirred as shown in the drawing, so that the RH supply diffusion process can be performed smoothly. it can.

  The processing container 4 shown in FIG. 2 is made of stainless steel, but the material is not limited to this, and has a heat resistance of 1000 ° C. or higher, an RTB-based sintered magnet material 1, alloy powder particles 2, and a stirring aid. Any material that does not easily react with any of the members 3 can be used. For example, an alloy containing at least one of Nb, Mo, and W, an Fe—Cr—Al alloy, an Fe—Cr—Co alloy, or the like may be used. The processing container 4 is provided with a lid 5 that can be opened and closed or removed. Moreover, you may install a protrusion in the inner wall of the processing container 4 so that the RTB system sintered magnet raw material 1, the alloy powder particle 2, and the stirring auxiliary member 3 can move efficiently. Furthermore, the shape of the processing container 4 may be an ellipse or a polygon as well as a circle. The processing container 4 is connected to an exhaust device 6, and the inside of the processing container 4 can be depressurized or pressurized by the exhaust device 6. A gas supply device (not shown) is connected to the processing container 4, and an inert gas or the like can be introduced into the processing container from the gas supply device.

  The processing container 4 is heated by a heater 7 disposed on the outer periphery thereof. A typical example of the heater 7 is a resistance heater that generates heat by an electric current. By heating the processing vessel 4, the RTB-based sintered magnet material 1, the alloy powder particles 2, and the stirring auxiliary member 3 charged therein are also heated. The processing container 4 is rotatably supported and can be rotated by the motor 8 during heating by the heater 7. As for the rotational speed of the processing container 4, it is preferable to set the peripheral speed of the inner wall surface of the processing container 4 to 0.1 m / min or more, for example.

  In the present embodiment, the temperatures of the RTB-based sintered magnet material 1, the alloy powder particles 2, and the stirring auxiliary member 3 in the processing container 4 reach substantially the same level. In the embodiment of the present disclosure, it is not necessary to heat Dy and Tb that are relatively hard to vaporize to, for example, a high temperature of 1000 ° C. or higher. Therefore, a temperature suitable for diffusing Dy and / or Tb into the inside of the R-T-B system sintered magnet material 1 through the grain boundary phase of the R-T-B system sintered magnet material 1 (800 RH supply diffusion treatment can be realized at a temperature of not less than 1000 ° C and not more than 1000 ° C.

  When the RTB-based sintered magnet material 1 and the alloy powder particles 2 come into contact with each other, the heavy rare earth element RH is supplied from the alloy powder particles 2 to the surface of the RTB-based sintered magnet material 1. The heavy rare earth element RH diffuses into the RTB-based sintered magnet material 1 through the grain boundary phase of the RTB-based sintered magnet material 1 during the RH supply diffusion process. . Such a method does not require the formation of a thick film of heavy rare earth element RH on the surface of the R-T-B system sintered magnet material 1, and therefore the temperature of the alloy powder particles 2 is R-T-B system. Even at a temperature almost equal to the temperature of the sintered magnet material 1 (800 ° C. or higher and 1000 ° C. or lower) (temperature difference is 50 ° C. or lower, for example), the supply and diffusion of the heavy rare earth element RH can be realized simultaneously.

  A thick film of heavy rare earth element RH is formed on the surface of the RTB-based sintered magnet material 1 by heating the alloy powder particles 2 to a high temperature and vaporizing Dy or Tb actively from the alloy powder particles 2. In order to form the RH, it is necessary to selectively heat the alloy powder particles 2 to a temperature significantly higher than that of the RTB-based sintered magnet material 1 during the RH supply diffusion treatment. Such heating cannot be performed by the heater 7 located outside the processing container 4, and needs to be performed by, for example, induction heating that radiates microwaves only to the alloy powder particles 2. In that case, since it is necessary to place the alloy powder particles 2 at a position away from the RTB-based sintered magnet material 1 and the stirring auxiliary member 3, as in the embodiment of the present disclosure, RT The B-based sintered magnet material 1, the alloy powder particles 2, and the stirring auxiliary member 3 cannot be stirred inside the processing container 4.

  The inside of the processing container 4 during heating is preferably in an inert atmosphere. The “inert atmosphere” in the present invention includes a vacuum or an inert gas atmosphere. The “inert gas” is a rare gas such as argon (Ar), for example, but chemically reacts with the RTB-based sintered magnet material 1, the alloy powder particles 2, and the stirring auxiliary member 3. Any gas that does not react is included in the “inert gas” in the present invention. The pressure in the processing container 4 is preferably 1 kPa or less.

  In the RH supply diffusion treatment of the present invention, it is preferable to maintain at least the temperature of the RTB-based sintered magnet material 1 and the alloy powder particles 2 within a range of 500 ° C. or higher and 1000 ° C. or lower, and 800 ° C. or higher and 1000 ° C. The following range is more preferable. The temperature range is such that the R—T—B system sintered magnet material 1 and the alloy powder particles 2 move relatively close to each other in the processing vessel, and the heavy rare earth element RH is sintered in the R—T—B system. This is a preferable temperature range in which the grain boundary phase inside the magnet material is diffused and diffused into the inside, and the diffusion of the heavy rare earth element RH into the RTB-based sintered magnet material is efficiently performed. . The holding time may be determined in consideration of the charged amount and shape of the RTB-based sintered magnet material 1, the alloy powder particles 2, and the stirring auxiliary member 3. The holding time is, for example, 10 minutes to 72 hours, preferably 1 hour to 14 hours. Further, FIG. 2 shows a configuration in which the processing container 4 rotates, but the processing container 4 may be swung or may be rotated and swung together.

[Example of heat pattern]
The temperature of the processing container during the RH supply diffusion process changes as shown in FIG. 3, for example. FIG. 3 is a graph showing an example of a change (heat pattern) in the processing chamber temperature after the start of heating. In the example of FIG. 3, evacuation was performed while the temperature was raised by the heater. The temperature rising rate is about 5 ° C./min. The temperature was maintained at, for example, about 600 ° C. until the pressure in the processing chamber reached a desired level. Thereafter, rotation of the processing chamber is started. The temperature was raised until the diffusion treatment temperature was reached. The temperature rising rate is about 5 ° C./min. After reaching the diffusion treatment temperature, the temperature is maintained for a predetermined time. Thereafter, heating by the heater was stopped and the temperature was lowered to about room temperature. Thereafter, the RTB-based sintered magnet material taken out from the apparatus of FIG. 2 is put into another heat treatment furnace, subjected to RH diffusion treatment (800 ° C. to 950 ° C. × 4 hours to 10 hours), and further after diffusion. Heat treatment (450 ° C. to 550 ° C. × 3 hours to 5 hours) is performed. Note that the heat pattern that can be executed by the diffusion processing of the present disclosure is not limited to the example illustrated in FIG. 3, and various other patterns can be employed. Further, evacuation may be performed until the diffusion treatment is completed and the sintered magnet material is sufficiently cooled.

  A method for separating the RTB-based sintered magnet, the alloy powder particles, and the stirring auxiliary member after the RH supply diffusion treatment may be performed by a known method, and the method is not particularly limited. For example, the punching metal may be separated by vibrating it.

After the RH supply diffusion treatment, the RH diffusion treatment may be performed in which the heavy rare earth element RH is diffused into the RTB-based sintered magnet without supplying the heavy rare earth element RH. As a result, the diffusion of the heavy rare earth element RH occurs in the RTB-based sintered magnet, so that the heavy rare earth element RH diffuses deeply from the surface side of the RTB-based sintered magnet. It is possible to increase H _cJ . In the RH diffusion treatment, the RTB-based sintered magnet is heated within a range of 700 ° C. or more and 1000 ° C. or less in a situation where the heavy rare earth element RH is not supplied from the alloy powder particles to the RTB-based sintered magnet. . The time for the RH diffusion process is, for example, 10 minutes to 72 hours. Preferably it is 1 to 12 hours.

  Furthermore, after the RH supply diffusion treatment or after the RH diffusion treatment, heat treatment may be performed for the purpose of improving the magnetic properties of the R-T-B based sintered magnet. This heat treatment is the same as the heat treatment performed after sintering in the known RT-B sintered magnet manufacturing method. Known conditions may be employed for the heat treatment atmosphere, the heat treatment temperature, and the like.

  Embodiments of the present invention will be described in more detail by way of examples, but the present invention is not limited to them.

<Example 1>
Using Nd metal, Pr metal, Dy metal, ferroboron alloy, electrolytic Co, Al metal, Cu metal, Ga metal and electrolytic iron (all metals are 99% or more in purity) Blended so as to have the composition of A-R-T-B sintered magnet material of A, these raw materials were respectively melted and cast by a strip cast method, and a flaky raw material having a thickness of 0.2 to 0.4 mm An alloy was obtained. The obtained flaky raw material alloy was hydrogen embrittled in a hydrogen-pressurized atmosphere and then subjected to dehydrogenation treatment by heating and cooling to 550 ° C. in a vacuum to obtain coarsely pulverized powder. Next, after adding and mixing 0.04 parts by mass of zinc stearate as a lubricant with respect to 100 parts by mass of the coarsely pulverized powder, the resulting coarsely pulverized powder is dry pulverized in a nitrogen stream using a jet mill device. As a result, finely pulverized powder having a particle diameter D ₅₀ of 4 μm was obtained. The particle diameter D ₅₀ is a volume-based median diameter obtained by a laser diffraction method using an air flow dispersion method.

After adding and mixing 0.05 parts by mass of zinc stearate as a lubricant with respect to 100 parts by mass of the finely pulverized powder, the finely pulverized powder was molded in a magnetic field to obtain a molded body. As the forming apparatus, a so-called perpendicular magnetic field forming apparatus (transverse magnetic field forming apparatus) in which the magnetic field application direction and the pressing direction are orthogonal to each other was used. The obtained molded body was sintered in vacuum at 1070 ° C. for 4 hours. An RTB-based sintered magnet material of A was obtained. The density of the RTB-based sintered magnet material was 7.5 Mg / m ³ or more. Table 1 shows the analysis results of the components of the obtained RTB-based sintered magnet material. In addition, each component in Table 1 was measured using high frequency inductively coupled plasma optical emission spectrometry (ICP-OES). O (oxygen amount) is a gas melting-infrared absorption method, N (nitrogen amount) is a gas melting-heat conduction method, and C (carbon amount) is a combustion-infrared absorption method. Measured. The obtained RTB-based sintered magnet material has a size of 50.5 mm × 8.5 mm × 5.5 mm, and has a rectangular shape as a whole. In addition, the eight corners of the RTB-based sintered magnet are chamfered with a radius of 1.0 mm.

Next Tb metal, TbFe ₃ (Tb48.7 wt%, Fe51.3 mass%) using an electrolytic iron were prepared starting alloy formulated such that. These raw material alloys were melted and cast by a strip casting method to prepare a flake-shaped TbFe ₃ alloy having a thickness of 0.2 to 0.4 mm. After pin milling the obtained TbFe ₃ alloy, it was passed through a JIS standard sieve shown in Table 2 to obtain No. 1 A plurality of alloy powder particles a to g were prepared. More specifically, the alloy powder particle Nos. a is an alloy powder particle obtained by passing a plurality of pin mill-ground alloy powder particles through a 1000 μm sieve and then passing through a 212 μm sieve and not passing through a 212 μm sieve through the 1000 μm sieve. In addition, alloy powder particle No. g is the alloy powder particles that passed through a 38 μm sieve. Alloy powder particle No. b to f, Tables 5 and 7 are also described in the same manner. Furthermore, a plurality of zirconia spheres having a diameter of 3 mm were prepared as stirring assist members.

  The RTB-based sintered magnet material, the plurality of alloy powder particles having a weight ratio of 3% with respect to the RTB-based sintered magnet material, and the RTB-based sintered magnet An agitation assisting member having a weight ratio of 200% with respect to the magnetized material was charged into the processing container shown in FIG. Specifically, the inner diameter of the processing vessel (inner diameter of the cylinder): about 300 mm, the length of the cylinder: about 1000 mm, the input weight of the R-T-B system sintered magnet material: about 35 kg (about 2000 pieces), RH diffusion The input weight of the source was about 1 kg, and the input amount of the stirring auxiliary member was about 70 kg. After the inside of the processing vessel was evacuated, Ar gas was introduced. And the inside of a processing container was heated and rotated, and RH supply diffusion processing was performed. The processing container was rotated at a peripheral speed of 0.3 m / min, and the temperature in the processing container was heated to 930 ° C. and held for 6 hours. Further, the RTB-based sintered magnet after the RH supply diffusion treatment was placed in another heat treatment furnace, and the heat treatment furnace was heated to 500 ° C. and held for 2 hours.

Table 3 shows the measurement results of the magnetic properties of the obtained RTB-based sintered magnet. B _r shown in Table 3, the value of H _cJ is subjected to machining on the whole surface of the R-T-B based sintered magnet after the heat treatment, the sample was 5mm (M) × 7mm × 7mm , measured by BH tracer did. Sample No. in Table 3 1 is an alloy powder No. 1; a and RTB-based sintered magnet material No. The RH supply diffusion process is performed using A. Sample No. 2-7 are described similarly.

As shown in Table 3, 3% by weight of alloy powder particles having a size of 90 μm or less are charged into the processing container in a weight ratio with respect to the R-T-B system sintered magnet material, and the processing container is heated and rotated. The R-T-B system sintered magnet (sample Nos. 4 to 7) in the embodiment of the present invention that has been subjected to the RH supply diffusion treatment is R- in the comparative example using alloy powder particles having a size exceeding 90 μm. Higher H _cJ is obtained as compared with the TB-based sintered magnet (Sample Nos. 1 to 3). In addition, when the particle size is 90 μm or more of alloy powder particles, H _cJ greatly fluctuates (H _cJ fluctuates in the range of 1493 kA / m to 1747 kA / m as in sample Nos. 1 to 3). Within the scope of the invention, high H _cJ can be obtained stably (as in Samples Nos. 4 to 7, H _cJ is in the range of 1920 kA / m to 2014 kA / m and fluctuation is small). In addition, as shown in Table 3, when the size is 38 μm or more and 75 μm or less (Sample Nos. 5 and 6 in the embodiment of the present invention), higher H _cJ is obtained more stably, and the size is further increased. A higher H _cJ is obtained in the case of 38 μm or more and 63 μm or less (sample No. 6 of the present invention).

  In addition, the obtained sample No. The chip | tip of the R-T-B type | system | group sintered magnet of 1-7 was evaluated. For evaluation of chipping, 20 R-T-B based sintered magnets were extracted, and the number ratio of R-T-B based sintered magnets in which chipping was equal to or greater than the volume of a sphere having a diameter of 1 mm was counted. Then, the occurrence rate of chipping is evaluated as 10% or less as the present invention. Sample No. 20 pieces of each of the 1 to 7 R-T-B sintered magnets were extracted and evaluated for chipping. All samples were within the scope of the present invention (the chipping rate was 10% or less). .

<Example 2>
In the same manner as in Example 1, the material No. A RTB-based sintered magnet material of A was prepared. Next, a TbFe ₃ alloy was prepared in the same manner as in Example 1, and was milled with a pin mill and applied to a 90 μm sieve (JIS standard) to prepare a plurality of alloy powder particles of 90 μm or less. Furthermore, a plurality of zirconia spheres having a diameter of 3 mm were prepared as stirring assist members.

  The alloy powder particles, the RTB-based sintered magnet material, and the stirring auxiliary member were charged into a processing vessel shown in FIG. Table 4 shows the weight ratio of the alloy powder particles to the RTB-based sintered magnet material. In Table 4, for example, Sample No. 8 shows that the alloy powder particles were charged at 1% by weight with respect to the RTB-based sintered magnet material. Sample No. 9 to 19 are also described in the same manner. RH supply diffusion treatment was performed in the same manner as in Example 1 except that the alloy powder particles were charged into the treatment container at a weight ratio shown in Table 4. Further, heat treatment was performed in the same manner as in Example 1.

Table 4 shows the measurement results of the magnetic properties of the obtained RTB-based sintered magnet. B _r shown in Table 4, the value of H _cJ was measured by the same manner as in Example 1..

As shown in Table 4, the RTB of the present invention obtained by charging the alloy powder particles in an amount of 2% to 15% by weight with respect to the RTB-based sintered magnet material. The sintered magnets (samples Nos. 9 to 14) are higher in weight ratio than the R-T-B sintered magnets (samples Nos. 8 and 15 to 19) of the comparative example that are outside the scope of the present invention. H _cJ is obtained. Furthermore, as shown in Table 4, _HcJ is higher when the weight ratio of the alloy powder particles to the _RTB -based sintered magnet material is 3% or more and 7% or less (Sample _{Nos. 10} to 12). Has been obtained. In addition, the obtained sample No. When the cracks of the 8 to 19 RTB-based sintered magnets were evaluated under the same conditions as in Example 1, all the samples were within the scope of the present invention (the occurrence rate of chips was 10% or less).

<Example 3>
In the same manner as in Example 1, the material No. A lot of R-T-B system sintered magnet materials of A were prepared. Next, a TbFe ₃ alloy was prepared in the same manner as in Example 1, and was pulverized with a pin mill and passed through a JIS standard sieve shown in Table 5. A plurality of lots of a plurality of alloy powder particles h to j were prepared. Furthermore, a plurality of zirconia spheres having a diameter of 3 mm were prepared as stirring assist members.

  The alloy powder particles, the RTB-based sintered magnet material, and the stirring auxiliary member were subjected to a plurality of lots of RH supply diffusion treatment under the same conditions as in Example 1. When the alloy powder particles (h to j) remaining after the RH supply diffusion treatment were observed for each lot by a field emission scanning electron microscope (FE-SEM), all lots had foreign matters other than the RH diffusion source on the entire surface. (For example, R oxide and R-T-B compound) were present. Further, the alloy powder particles of each lot remaining after the RH supply diffusion treatment are collected, respectively, and the collected alloy powder particles (h to j), the other lots of the RTB-based sintered magnet material, and the stirring assist RH supply diffusion treatment was performed in the same manner as in Example 1 using the members. Further, heat treatment was performed in the same manner as in Example 1. In addition, the magnitude | size of the alloy powder (hj) hardly changed before and after the said RH supply diffusion process.

Table 6 shows the measurement results of magnetic properties of the obtained RTB-based sintered magnet. B _r shown in Table 6, the value of H _cJ was measured by the same manner as in Example 1..

As shown in Table 6, even when the RH supply / diffusion treatment was repeatedly performed using the alloy powder particles once subjected to the RH supply / diffusion treatment, the RTB-based sintered magnet (sample No. 1) of the present invention was used. In _Nos . 21 and 22), a high H _cJ is obtained as compared with the R-T-B system sintered magnet (sample No. 20) of the comparative example using alloy powder particles having a size exceeding 90 μm. Moreover, high _HcJ is _stably obtained (1881 kA / m and 1890 kA / m) within the scope of the present invention. In addition, the obtained sample No. When 20 to 22 R-T-B sintered magnets were evaluated for chipping under the same conditions as in Example 1, all the samples were within the scope of the present invention (the chipping rate was 10% or less).

<Example 4>
A plurality of lots of RTB-based sintered magnet material and a plurality of alloy powder particles h to j are prepared in the same manner as in the third embodiment, and a plurality of lots of RH supply diffusion treatment are performed in the same manner as in the third embodiment. I went for a minute. Then, the alloy powder particles of each lot remaining after the RH supply diffusion are collected, pin milled (pulverized to such an extent that the alloy powder particles do not become too small), and again passed through a JIS standard sieve shown in Table 7 to obtain No. A plurality of alloy powder particles h ′ to j ′ were prepared. The alloy powder particles (h ′ to j ′) were observed with a field emission scanning electron microscope (FE-SEM). As a result, the surface of the alloy powder particles (h ′ to j ′) other than the RH diffusion source (for example, R oxide or RTB). It was confirmed that there was a portion where the (compound) was not present (the portion where the nascent surface was exposed was confirmed). Furthermore, a plurality of zirconia spheres having a diameter of 3 mm were prepared as stirring assist members.

  Next, an RTB-based sintered magnet material is prepared in the same manner as in Example 3, and the RTB-based sintered magnet material, the alloy powder particles (h ′ to j ′), and the stirring are prepared. The RH supply diffusion treatment was performed by the same method as in Example 1 using the auxiliary member. Further, heat treatment was performed in the same manner as in Example 1.

Table 8 shows the measurement results of magnetic properties of the obtained RTB-based sintered magnet. B _r shown in Table 8, the value of H _cJ was measured by the same manner as in Example 1..

As shown in Table 8, the RTB-based sintered magnet (No. 24) of the present invention in which the alloy powder particles after the RH supply diffusion treatment were pulverized and the new surface was exposed on at least a part of the alloy powder particles. And 25) is higher than the RTB-based sintered magnet (No. 21 and 22) of the present invention of Example 3 in which the nascent surface is not exposed on at least a part of the alloy powder particles. H _cJ is obtained. In addition, the obtained sample No. When 23 to 25 RTB-based sintered magnets were evaluated for chipping under the same conditions as in Example 1, all the samples were within the scope of the present invention (the chipping rate was 10% or less).

<Example 5>
In the same manner as in Example 1, the material No. A lot of R-T-B system sintered magnet materials of A were prepared. Next, using Tb metal and electrolytic iron, alloy powder Nos. An alloy was prepared in the same manner as in Example 1 by blending so as to have the composition shown in w-1 to w-5. The obtained alloy was subjected to pin mill pulverization and passed through a 90 μm sieve (JIS standard) to prepare a plurality of alloy powder particles of 90 μm or less (alloy powder Nos. W-1 to w-5), respectively. . Furthermore, a plurality of zirconia spheres having a diameter of 3 mm were prepared as stirring assist members.

  Next, RH supply diffusion treatment was performed under the same conditions as in Example 1 using the plurality of alloy powder particles, the RTB-based sintered magnet material, and the stirring auxiliary member under the conditions shown in Table 10. Further, heat treatment was performed in the same manner as in Example 1. The magnetic properties of the obtained RTB-based sintered magnet were measured by the same method as in Example 1. The measurement results are shown in Sample No. 26-30. Sample No. in Table 10 No. 26 is an alloy powder no. w-1 and RTB-based sintered magnet material No. The RH supply diffusion process is performed using A. Sample No. 27 to 30 are also described in the same manner.

As shown in Table 10, Sample No. using a plurality of alloy powder particles containing less than 35% by mass of the heavy rare earth element RH (Tb). 30 using a plurality of alloy powder particles containing 35% by mass or more of heavy rare earth element RH. Higher H _cJ is obtained for _26-29 . Furthermore, Sample No. using a plurality of alloy powder particles containing heavy rare earth element RH 40 mass% or more and 60 mass% or less. A higher H _cJ is obtained for 26-28. Accordingly, the plurality of alloy powder particles preferably contain 35% by mass or more of heavy rare earth element RH, and more preferably contain 40% by mass or more and 60% by mass or less. In addition, the obtained sample No. When 26 to 30 RTB-based sintered magnets were evaluated for chipping under the same conditions as in Example 1, all the samples were within the scope of the present invention (the chipping rate was 10% or less).

<Example 6>
In the same manner as in Example 1, the material No. A RTB-based sintered magnet material of A was prepared. Next, a TbFe ₃ alloy was prepared in the same manner as in Example 1. Next, a plurality of alloy powder particles were prepared by performing hydrogen pulverization on the TbFe ₃ alloy. In hydrogen pulverization, first, TbFe ₃ is charged into a hydrogen furnace, and then hydrogen supply to the hydrogen furnace is started at room temperature, and a hydrogen occlusion process for maintaining the absolute pressure of hydrogen at about 0.3 MPa is performed for 90 minutes. It was. In this step, the hydrogen in the furnace was consumed with the hydrogen occlusion reaction of the alloy powder, and the hydrogen pressure decreased. Therefore, hydrogen was additionally supplied to compensate for the decrease, and the pressure was controlled to about 0.3 MPa.

  Next, a dehydrogenation step of heating in vacuum at each dehydrogenation temperature shown in Table 11 for 8 hours was performed. The amount of hydrogen was measured by heating / dissolving column separation-thermal conductivity method (TCD) of a plurality of alloy powder particles after hydrogen pulverization in an Ar atmosphere. Table 11 shows the measurement results. Furthermore, a plurality of zirconia spheres having a diameter of 3 mm were prepared as stirring assist members.

  The same method as in Example 1 using the plurality of hydrogen-pulverized alloy powder particles, the RTB-based sintered magnet material, and the stirring auxiliary member that are not classified using a sieve having an opening of 90 μm RH supply diffusion treatment was performed. Further, heat treatment was performed in the same manner as in Example 1. For confirmation, when a plurality of alloy powder particles after hydrogen pulverization were passed through a 90 μm sieve, all of them were a plurality of alloy powder particles having a weight ratio of 90% or more and 90 μm or less.

  The magnetic properties of the obtained RTB-based sintered magnet were measured by the same method as in Example 1. Table 11 shows the measurement results.

As shown in Table 11, when a plurality of alloy powder particles are obtained by performing hydrogen pulverization, heating is performed to 400 ° C. or more and 550 ° C. or less in the dehydrogenation process (dehydrogenation temperature is 400 ° C. or more and 550 ° C. or less. ) In the present invention (sample Nos. 32-34) subjected to hydrogen pulverization, high H _cJ is obtained. Further, within the scope of the invention, a high H _cJ is _stably obtained (1998 kA / m to 2013 kA / m). In contrast, Sample No. whose dehydrogenation heat temperature is outside the scope of the present invention. For 31 and 35, the R-T-B system sintered magnet was hydrogen embrittled after the RH supply diffusion treatment, so the magnetic properties could not be measured. This is because, as shown in Table 11, the hydrogen content of the plurality of alloy powder particles (sample Nos. 32 to 34) produced under the hydrogen pulverization conditions of the present invention was tens of ppm, although hydrogen hardly remained. On the other hand, the hydrogen content of the plurality of alloy powder particles (sample Nos. 31 and 35) having a dehydrogenation temperature outside the range of the present invention is several hundred ppm, and a large amount of hydrogen remains. Therefore, at the time of the RH supply diffusion treatment, hydrogen is supplied from a plurality of alloy powder particles to the RTB-based sintered magnet material, so that the finally obtained RTB-based sintered magnet is hydrogen. It is thought that it became brittle. In addition, the obtained sample No. When the chipping of the 32-34 RTB-based sintered magnets was evaluated under the same conditions as in Example 1, all the samples were within the scope of the present invention (the occurrence rate of chipping was 10% or less).

<Reference Example 1>
In the same manner as in Example 1, the material No. A RTB-based sintered magnet material of A was prepared. Next, a TbFe ₃ alloy was prepared and pin milled in the same manner as in Example 1 and passed through a 63 μm sieve, and then the alloy powder particles that passed through the 63 μm sieve were passed through the 38 μm sieve and did not pass through the 38 μm sieve. Powder particles were prepared. 3% of the alloy powder particles were prepared with respect to the weight of the RTB-based sintered magnet material, and a turbid liquid in which the prepared alloy powder particles were mixed with alcohol at a mass fraction of 50% was prepared. The said turbid liquid was apply | coated to the surface (entire surface) of the R-T-B type | system | group sintered magnet raw material, and it was made to dry with warm air.

The RTB-based sintered magnet material covered with TbFe ₃ was subjected to an RH supply diffusion treatment step of heating to 930 ° C. in an Ar atmosphere and holding for 6 hours. Further, heat treatment was performed in the same manner as in Example 1.

  The magnetic properties of the obtained RTB-based sintered magnet were measured by the same method as in Example 1. Table 12 shows the measurement results.

In Reference Example 1, not the RH supply diffusion process of the present invention but the RH supply diffusion process performed by the method described in Patent Document 2. Sample No. in Table 9 Sample No. 36 of Example 1 is different except that the RH supply diffusion treatment is different. 6 and the same composition and method. As shown in Table 12, sample no. 36 is a sample No. 36. Compared to 6, H _cJ is greatly reduced. That is, in the RH supply diffusion process described in Patent Document 2, alloy powder particles having a specific size of the present invention are used, and the amount of the alloy powder particles having the specific size is set to R-T-B system sintering. Even if it is a specific ratio of this invention with respect to the weight ratio of a magnet raw material, high _HcJ cannot be obtained.

<Example 7>
In the same manner as in Example 1, the material No. A RTB-based sintered magnet material of A was prepared. Next, a TbFe ₃ alloy was prepared in the same manner as in Example 1, and was milled with a pin mill and applied to a 90 μm sieve (JIS standard) to prepare a plurality of alloy powder particles of 90 μm or less. In addition, a plurality of zirconia balls having a diameter of 1 to 7 mm were prepared as stirring assist members.

  RH supply diffusion treatment was performed using the alloy powder particles, the RTB-based sintered magnet material, and the stirring auxiliary member. In the RH supply diffusion treatment, the RH supply diffusion treatment was performed in the same manner as in Example 1 except that a stirring auxiliary member having a size shown in Table 13 was used. Sample No. in Table 13 No. 41 is the same method as in Example 1 except that 70% of the plurality of stirring auxiliary members by weight ratio use a stirring auxiliary member with a diameter of 2 mm, and 30% use a stirring auxiliary member with a diameter of 7 mm. The RH supply diffusion treatment is performed. Sample No. 37 to 40 and 42 and 43 are also described in the same manner. Further, heat treatment was performed in the same manner as in Example 1.

  The magnetic properties of the obtained RTB-based sintered magnet were measured by the same method as in Example 1. Table 13 shows the measurement results. In addition, the obtained sample No. The chipping of 37 to 43 RTB-based sintered magnets was evaluated under the same conditions as in Example 1. The evaluation results are shown in Table 13. In Table 13, when the evaluation of chipping is within the range of the present invention (the generation rate of chipping is 10% or less), it is described as ◯, and when it is out of the range (the generation rate of chipping is more than 10%), it is described as x. .

  As shown in Table 13, the present invention (sample Nos. 37 to 39) in which 65% or more of the stirring assisting members of the plurality of stirring assisting members by weight ratio has a size of 0.5 mm or more and 4 mm or less. 41, 43) were all within the scope of the present invention (the occurrence rate of chipping was 10% or less). On the other hand, when the size of the stirring assisting member was outside the range of the present invention (Sample Nos. 40 and 42), many chips were generated.

  According to the present invention, it is possible to produce an RTB-based sintered magnet having a high residual magnetic flux density and a high coercive force. 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.

DESCRIPTION OF SYMBOLS 1 RTB type sintered magnet raw material 2 Alloy powder particle 3 Stirring auxiliary member 4 Processing container 5 Lid 6 Exhaust device 7 Heater 8 Motor

Claims (12)

A plurality of R-T-B sintered magnet materials (R is at least one of rare earth elements and always contains at least one of Nd and Pr, T is at least one of transition metal elements and always contains Fe) )
Preparing a plurality of alloy powder particles having a size of 90 μm or less, containing 20% by mass to 80% by mass of heavy rare earth element RH (heavy rare earth element RH is at least one of Tb and Dy);
A step of preparing a stirring assisting member having a diameter of 0.5 mm or more and 4 mm or less, wherein the stirring assisting member is a plurality of stirring assisting members, and 65% or more of the stirring assisting members of the plurality of stirring assisting members are by weight.
The plurality of R-T-B system sintered magnet materials, the alloy powder particles having a weight ratio of 2% to 15% with respect to the plurality of R-T-B system sintered magnet materials, A step of charging the stirring auxiliary member in a weight ratio of 100% to 500% with respect to a plurality of R-T-B system sintered magnet materials;
By heating and rotating and / or swinging the processing vessel, the RTB-based sintered magnet material, the alloy powder particles, and the stirring assisting member are moved continuously or intermittently to cause RH. Performing a supply diffusion process;
The manufacturing method of the RTB type | system | group sintered magnet containing this.   The manufacturing method of the RTB type | system | group sintered magnet of Claim 1 which heats the said process container to the process temperature of 800 to 1000 degreeC in the process of performing the said RH supply diffusion process.   3. The method for producing an RTB-based sintered magnet according to claim 1, wherein each of the plurality of alloy powder particles has a size of 38 μm or more and 75 μm or less.   4. The weight ratio of the plurality of alloy powder particles charged into the processing vessel to the RTB-based sintered magnet material is 3% or more and 7% or less. 5. Of manufacturing an R-T-B system sintered magnet.   The RTB-based sintered magnet according to any one of claims 1 to 4, wherein the plurality of alloy powder particles contain alloy powder particles in which a new surface is exposed at least partially. Production method.   6. The method for producing an RTB-based sintered magnet according to claim 1, wherein the plurality of alloy powder particles contain the heavy rare earth element RH in an amount of 35 mass% to 65 mass%.   The method for producing an RTB-based sintered magnet according to any one of claims 1 to 6, wherein the heavy rare earth element RH is Tb. The plurality of RTB-based sintered magnet materials have a volume of 1000 mm ³ or more, and a maximum size of three sizes in three orthogonal directions is twice or more a minimum size. The manufacturing method of the RTB type | system | group sintered magnet in any one of 1-7.   Each of the plurality of sintered magnet materials has a rectangular parallelepiped shape in which the length of one side is 40 mm or more and the length of each of the other two sides is 10 mm or less, or a substantially rectangular shape that is chamfered at each vertex position. The manufacturing method of the RTB type | system | group sintered magnet of Claim 8 which has these.   Each of the plurality of stirring assisting members is formed of ceramics of zirconia, silicon nitride, silicon carbide, boron nitride, or a mixture thereof, according to any one of claims 1 to 9. Manufacturing method of B system sintered magnet.   The RTB-based sintered magnet material supplied with the heavy rare earth element RH from any one of the plurality of alloy powder particles in the RH supply diffusion process is in a non-contact state with the alloy powder particles And the manufacturing method of the RTB system sintered magnet in any one of Claim 1 to 10 including the process of heating and performing RH diffusion process.   The plurality of alloy powder particles are produced by hydrogen pulverizing an alloy containing 35% by mass or more and 50% by mass or less of heavy rare earth element RH (heavy rare earth element RH is Tb and / or Dy). The manufacturing method of the RTB type | system | group sintered magnet in any one of Claim 1 to 11 which heats the said alloy to 400 to 550 degreeC in a dehydrogenation process.

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