JP6512150B2 - Method of manufacturing RTB based sintered magnet - Google Patents

Description

  The present invention relates to a method of 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 of rare earth elements and necessarily includes 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 include various motors such as voice coil motors (VCM) for hard disk drives, motors for electric vehicles (including EV, HV and PHV), motors for industrial equipment, home appliances, etc. It is used for various purposes.

The RTB-based sintered magnet is composed of a main phase composed of a compound having an R ₂ T ₁₄ B crystal structure, and a grain boundary phase located in a grain boundary portion of the main phase. The R ₂ T ₁₄ B phase which is the main phase is a ferromagnetic phase and mainly contributes to the magnetizing action of the RTB-based 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 a heavy rare earth element RH (mainly Dy) It is known that coercivity H _cJ (hereinafter sometimes simply referred to as “H _cJ ”) is improved by substitution with and / or Tb). That is, in order to improve _HcJ , it is necessary to use many heavy rare earth elements RH.

However, replacing the light rare earth element RL in the R ₂ T ₁₄ B phase with the heavy rare earth element RH in the RTB-based sintered magnet improves H _cJ while reducing the residual magnetic flux density B _r (hereinafter simply referred to as “ B _r ") is lowered. Therefore, it is required to improve H _cJ without lowering B _r by using less heavy rare earth element RH. In addition, since the heavy rare earth element RH is a rare metal, it is required to reduce its usage.

In recent years, in order to improve the _HcJ of RTB-based sintered magnets, heavy rare earth elements RH such as Dy and Tb are supplied to the surface of RTB-based sintered magnets, and the heavy rare earth elements RH are used as magnets. A method has been proposed to improve H _cJ while suppressing the decrease in B _r by diffusing _inward .

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

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

  In Patent Document 3, a plurality of R-T-B-based sintered magnet bodies and a plurality of RH diffusion sources containing a heavy rare earth element RH can be relatively moved and brought close to or in contact with each other in a processing chamber. Heavy rare earth element from the RH diffusion source by charging and heating while moving the RTB-based sintered magnet and the RH diffusion source continuously or intermittently in the processing chamber The method of making it diffuse to the inside of a sintered compact is described, supplying RH to the surface of the said RTB type | system | group sintered magnet body.

WO 2007/102391 WO 2006/043348 International Publication No. 2011/077558

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, in the method described in Patent Document 1, since the sintered body and the bulk body containing the heavy rare earth element RH need to be arranged separately, the process for the arrangement takes time and effort. Moreover, the method of patent document 2 takes an effort in the process of apply | coating to a sintered compact the slurry which disperse | distributed the powder containing Dy and Tb to a solvent. On the other hand, according to the method described in Patent Document 3, the RH diffusion source and the RTB-based sintered magnet body are inserted into the processing chamber and moved continuously or intermittently. Specifically, the processing vessel is rotated and / or rocked. Therefore, it is not necessary to separate the RTB-based sintered magnet body and the RH diffusion source from each other, and it is also necessary to apply a slurry dispersed in a solvent or a slurry dispersed in a solvent to the sintered body. Absent. According to the method of Patent Document 3, the heavy rare earth element RH can be diffused to the inside of 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 There were times when I could not get

  In addition, as RTB-based sintered magnets exhibiting high coercivity, magnets having various shapes as compared with the prior art have been required. For example, there is a demand for an RTB-based sintered magnet having a shape extending in one direction, having a size of 5 mm long × 5 mm wide × 50 mm long. When the technology described in Patent Document 3 is applied to the raw material of the RTB-based sintered magnet having such an anisotropic shape, the RTB-based sintered magnet raw material It was found that cracking and chipping may occur in part.

  The present disclosure provides a method of manufacturing a novel RTB-based sintered magnet.

  In one aspect, the method of producing an RTB-based sintered magnet according to the present disclosure includes a plurality of RTB-based sintered magnet materials (R is at least one of rare earth elements, Nd and Pr). A step of preparing at least one of T, at least one of transition metal elements and always containing Fe, and 20 mass% or more of heavy rare earth element RH (heavy rare earth element RH is at least one of Tb and Dy) 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 agitation assisting members, wherein 65% of the total of the plurality of agitation assisting members in weight ratio Preparing a stirring aid member having a diameter of 0.5 mm or more and 4 mm or less, the plurality of R-T-B-based sintered magnet materials, and the plurality of R-T-B Based sintered magnet material And 2% or more and 15% or less by weight ratio, and 100% or more and 500% or less by weight ratio with respect to the plurality of RTB-based sintered magnet materials The R-T-B-based sintered magnet material, the alloy powder particle, and the stirring auxiliary member are provided by the steps of: Moving continuously or intermittently to perform RH supply diffusion processing.

  In one embodiment, in the step of performing the RH supply diffusion process, the processing container is heated to a processing temperature of 800 ° C. or more and 1000 ° C. or less.

  In one embodiment, the plurality of alloy powder particles have 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 in part.

  In one embodiment, the plurality of alloy powder particles contain 35% by mass or more and 65% by mass or less of the heavy rare earth element RH.

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

In one embodiment, the plurality of R-T-B-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 the minimum size It is.

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

  In one embodiment, each of the plurality of stirring aids is formed of a ceramic of zirconia, silicon nitride, silicon carbide, boron nitride, or a mixture thereof.

  In one embodiment, the R-T-B-based sintered magnet material to which the heavy rare earth element RH is supplied from any of the plurality of alloy powder particles in the step of the RH supply and diffusion treatment is the alloy powder particles. In the non-contact state, the process of heating and performing RH diffusion processing is included.

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

According to the embodiments of the present disclosure, stable and high H _cJ can be obtained. Moreover, even if the RTB-based sintered magnet material has a shape that is easily chipped, the effect of reducing the occurrence of cracking and chipping can also be obtained.

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

As a result of the study according to the present invention, according to the method described in Patent Document 3, when the individual RH diffusion sources are too large or there are many small RH diffusion sources, the RTB sintered magnet can be obtained. It has been found that the supply of the heavy rare earth element RH is insufficient and high H _cJ can 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 in the processing vessel is in an appropriate range. By adjusting the stirring assist member having a diameter of 0.5 mm or more and 4 mm or less, it is possible to stably obtain a high H _cJ , and further, a _{shape in} which the _RTB -based sintered magnet material is easily chipped It has been found that the effect of reducing the occurrence of cracking and chipping can also be obtained even if the

  The manufacturing method of the RTB-based sintered magnet of the present disclosure is, in a non-limiting exemplary embodiment, a step of preparing a plurality of RTB-based sintered magnet materials; Preparing a plurality of alloy powder particles having a size of 90 μm or less and containing 20 mass% or more and 80 mass% or less, and a plurality of stirring assisting members each having a diameter of 0.5 mm or more and 4 mm or less And preparing the

  Here, 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 necessarily includes Fe. The heavy rare earth element RH is at least one of Tb and Dy. In addition, the stirring assistance member which occupies 65% or more of the whole stirring assistance member by a weight ratio has a diameter of 0.5 mm or more and 4 mm or less, respectively. The diameter of each of the stirring aid members that occupy 65% or more of the entire stirring aid member by weight ratio may be 1 mm or more and 3 mm or less in one aspect, and 2 mm or more 3 mm or less in another aspect.

  The manufacturing method of the RTB-based sintered magnet of the present disclosure further includes, in a non-limiting exemplary embodiment, the plurality of RTB-based sintered magnet materials, and the plurality of R-based sintered magnets. 100% by weight ratio of the alloy powder particles of 2% or more and 15% or less by weight ratio to a sintered material of a T-B based sintered magnet and the plurality of R-T-B sintered magnet materials R-T-B-based sintered magnet material and alloy powder by heating the processing container and rotating and / or rocking while charging the processing aid with the above-mentioned stirring auxiliary member of 500% or less and the processing container. Moving the particles and the stirring aid continuously or intermittently to perform the RH supply diffusion process.

  In the step of performing the RH supply diffusion process, each alloy powder particle containing the heavy rare earth element RH in an amount of 20% by mass to 80% by mass functions as an RH diffusion source. When the processing container is rotating and / or swinging, in the heated processing container, the RTB-based sintered magnet material and the alloy powder particles are agitated and come in contact with each other or are separated after the contact. Repeat the thing. At this time, the agitation assisting member promotes agitation of the RTB-based sintered magnet material and the alloy powder particles, so that the RTB-based sintered magnet material, the alloy powder particles, and the agitation assisting member are: It flows and moves in the processing vessel. The weight ratio of the stirring auxiliary member charged into the processing vessel to the RTB-based sintered magnet material charged into 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 heavy rare earth element RH (heavy rare earth element RH is Tb and / or Dy) in an amount of 35% by mass to 50% by mass. In the dehydrogenation step in the hydrogen grinding, the alloy is heated to 400 ° C. or more and 550 ° C. or less.

In the method described in Patent Document 3, the size of the RH diffusion source is not particularly limited. In addition, Patent Document 3 does not describe how to insert an RH diffusion source of a specific size into an RTB-based sintered magnet material. As a result of examining the method described in Patent Document 3 in detail, the present inventors prepared alloy powder particles of a specific size as an RH diffusion source, and of the alloy powder particles of the specific size. It has been found that by _{setting the loading amount} to a specific ratio to the weight ratio of the _RTB -based sintered magnet material, it is possible to stably obtain high _HcJ .

  In the present disclosure, while the heavy rare earth element RH is supplied to the RTB-based sintered magnet material, the diffusion of the heavy rare earth element RH into the magnet is referred to as “RH supply diffusion processing”. In addition, after the RH supply diffusion process is performed, diffusion of the heavy rare earth element RH into the R-T-B-based sintered magnet without supplying the heavy rare earth element RH is referred to as "RH diffusion process". Furthermore, heat treatment performed for the purpose of improving the magnet characteristics of the RTB-based sintered magnet after RH supply diffusion treatment or after RH diffusion treatment is simply referred to as “heat treatment”.

[Step of preparing a plurality of RTB based sintered magnet materials]
In the embodiment of the present invention, an RTB-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 The RTB based sintered magnet material manufactured according to the known composition and manufacturing method can be used in the following.

  In the present disclosure, RTB-based sintered magnets before RH supply diffusion processing and during RH supply diffusion processing are referred to as “RTB-based sintered magnet materials”, and RT after RT-supply diffusion processing. The -B-based sintered magnet is referred to as "R-T-B-based sintered magnet".

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

  The R-T-B-based sintered magnet material of the above composition is manufactured by a known manufacturing method.

The plurality of sintered magnet materials that can be used in the embodiments of the present disclosure have, for example, a volume of 1000 mm ³ or more, respectively, and a maximum size of three sizes in three orthogonal directions is twice the minimum size It is above.

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

  In one embodiment, each of the plurality of sintered magnet materials has a rectangular parallelepiped shape in which one side has a length (L) of 40 mm or more and the other two sides (D, H) has a length of 20 mm or less. doing. In another embodiment, each of the plurality of sintered magnet materials may have a substantially rectangular parallelepiped shape with a length of 40 mm or more on one side and a length of 10 mm or less on the other two sides. The individual sintered magnet materials may be chamfered at each vertex position, as shown in FIG. 1 (b). By chamfering, the occurrence of cracking and chipping can be further suppressed.

  In addition, the shape and size of the sintered magnet raw material to which the manufacturing method of this indication is applied are not limited to said example.

[Step of preparing a plurality of alloy powder particles]
The present invention prepares a plurality of alloy powder particles having a size of 90 μm or less and containing 20% by mass to 80% by mass of the heavy rare earth element RH as an RH diffusion source. In the present invention, the heavy rare earth element RH is Tb and / or Dy, and for example, a TbFe alloy, a DyFe alloy, etc. containing 20% by mass to 80% by mass of Tb and / or Dy can be used. Higher _HcJ can be obtained using Tb than Dy. If the heavy rare earth element RH is less than 20% by mass, the amount of the heavy rare earth element RH supplied may be small, and high H _cJ may not be obtained. In addition, when the heavy rare earth element RH exceeds 80% by mass, there is a risk that the RH diffusion source may ignite when the RH diffusion source is introduced 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, it can be classified and prepared using a sieve with an opening of 90 μm (JIS Z 8801-2000 standard sieve). If alloy powder particles having a size of 90 μm or less are not used, high H _cJ can not be stably obtained. Alloy powder particles having a size of 90 μm or less are obtained by pulverizing an alloy containing heavy rare earth element RH in an amount of 20% by mass to 80% by mass using a known method such as a pin mill crusher, and a sieve having an opening of 90 μm. It can prepare by using and classifying.

  When a plurality of alloy powder particles having a size of 90 μm or less are produced using a known method such as a pin mill crusher, it takes a long time to grind the alloy to 90 μm or less, or several times In some cases, this may cause the deterioration of mass productivity. Therefore, in place of these methods, hydrogen is absorbed in an alloy containing heavy rare earth element RH of 35% by mass to 50% by mass, and then a dehydrogenation step of heating to 400 ° C. or more and 550 ° C. or less is performed. You may Thereby, most of the plurality of alloy powder particles (90% or more by weight ratio) can be crushed to a size of 90 μm or less, so the size is 90 μm or less in a relatively large amount at one time. And a plurality of alloy powder particles can be obtained. Therefore, it is possible to load a plurality of alloy powder particles as they are into the processing container without performing classification using a sieve with an opening of 90 μm, and to perform RH supply diffusion processing. In this case, when a plurality of alloy powder particles are charged at 2%, which is the lower limit of the weight ratio, to the R-T-B sintered magnet material and subjected to RH supply diffusion processing, a plurality of particles having a size of 90 μm or less Since there is a possibility that the weight ratio of individual alloy powder particles may be 2% or less, it is preferable to charge 2.2% or more by weight ratio.

  When the hydrogen pulverization is performed, an alloy containing 35 to 50 mass% 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, there is a possibility that the alloy can not be pulverized to a size of 90 μm or less. On the other hand, when the content of the heavy rare earth element RH exceeds 50% by mass, a large amount of hydrogen may be left. Therefore, the content of the heavy rare earth element RH is preferably 35% by mass or more and 50% by mass or less. Hydrogen grinding is performed on the alloy. Hydrogen grinding is performed by causing the alloy to temporarily store hydrogen and then releasing hydrogen. Therefore, hydrogen grinding has a hydrogen storage step and a dehydrogenation step. The hydrogen storage step in the hydrogen pulverization of the present invention may be performed by a known method. For example, after the alloy is charged into the hydrogen furnace, hydrogen supply into the hydrogen furnace is started at room temperature, and a hydrogen storage process for maintaining the absolute pressure of hydrogen at about 0.3 MPa is performed for 90 minutes. In this process, hydrogen in the furnace is consumed along with the hydrogen storage reaction of the alloy powder, and the pressure of hydrogen is lowered. Therefore, additional hydrogen is supplied to control the pressure to about 0.3 MPa to compensate for the decrease. In the dehydrogenation step, the alloy after the hydrogen absorption step is heated to 400 ° C. or more and 550 ° C. or less in vacuum. By this, it is possible to grind to a size of 90 μm or less with almost no hydrogen remaining. When the heating temperature is lower than 400 ° C. and higher than 550 ° C., hydrogen will remain (about several hundred ppm) in the plurality of alloy powder particles. When hydrogen remains, hydrogen is supplied from the plurality of alloy powder particles to the RTB-based sintered magnet material during the subsequent RH feed diffusion processing, and the RTB-based sintered magnet finally obtained However, hydrogen embrittlement makes it impossible to use as a product. Therefore, the heating temperature in the dehydrogenation step is preferably 400 ° C. or more and 550 ° C. or less.

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. It is because high H _cJ can be obtained more stably. In addition, when the alloy powder particles smaller than 38 μm are contained in a large amount, the alloy powder particles are too small, which may cause the RH diffusion source to ignite. The alloy powder particles may contain at least one of Nd, Pr, La, Ce, Zn, Zr, Sm and Co in addition to Tb, Dy and Fe, as long as the effects of the present invention are not impaired. Further, as unavoidable impurities, Al, Ti, V, Cr, Mn, Ni, Cu, Ga, Nb, Mo, Ag, In, Hf, Ta, W, Pb, Si, Bi and the like 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 in part. In the present invention, the fact that the new surface is exposed means a foreign substance other than the RH diffusion source on the surface of the alloy powder particle, such as R oxide or R-T-B compound (compound having a composition close to the main phase) States that do not exist. As described above, since the plurality of alloy powder particles are prepared by crushing an alloy containing the heavy rare earth element RH in the range of 20% by mass to 80% by mass, the plurality of alloy powder particles obtained therefrom is at least It has alloy powder particles in which a new surface is exposed in part. However, when performing the RH supply diffusion process repeatedly, that is, changing to the RTB-based sintered magnet after the RH supply diffusion process, and preparing a plurality of new RTB-based sintered magnet materials When performing the RH supply diffusion process again using the plurality of RTB-based sintered magnet materials and the (used) alloy powder particles after the RH supply diffusion process, Even if a plurality of alloy powder particles having a size of 90 μm or less are present after the supply diffusion process, the entire surface of the alloy powder particles is covered with foreign matter, R oxide, etc. after the RH supply diffusion process. Surface may not be exposed. Therefore, in the case where the RH supply and diffusion process is repeated using the alloy powder particles after the treatment, when the supply of the heavy rare earth element RH to the RTB-based sintered magnet material is reduced due to foreign substances, R oxides, etc. There is. Therefore, it is preferable to grind | pulverize with respect to the several alloy powder particle | grains after a process by a well-known grinder etc., and to make the fracture | rupture surface of alloy powder particle | grains exposed, ie, the state in which the new surface was exposed.

[Step of charging RTB-based sintered magnet material and alloy powder particles into processing chamber]
A plurality of alloy powder particles having a weight ratio of 2% to 15% by weight based on the plurality of RTB-based sintered magnet materials and the plurality of RTB-based sintered magnet materials; Into the processing vessel. Thereby, high _HcJ can be stably obtained by performing the process of performing the RH supply diffusion process described later. When the weight ratio of the plurality of alloy powder particles having a size of 90 μm or less is less than 2% with respect to the RTB-based sintered magnet material, the amount of the alloy powder particles having a size of 90 μm or less is too small. It is not possible to obtain high H _cJ . Also, if it exceeds 15%, the alloy powder particles react excessively with the liquid phase exuded from the RTB based sintered magnet material, and abnormally adhere to the surface of the RTB based sintered magnet material Phenomenon occurs. Since a state where new heavy rare earth element RH is difficult to be supplied to the RTB-based sintered magnet material is formed by this phenomenon, it is not possible to _stably obtain high _HcJ . Therefore, although alloy powder particles of 90 μm or less are necessary to stably obtain high H _cJ , the amount thereof 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 ratio with respect to the plurality of RTB-based sintered magnet materials. It 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 a plurality of R-T-B sintered magnet materials by 2% or more and 15% or less, that is, the embodiment of the present invention described above In addition to the above, for example, a plurality of alloy powder particles having a size of more than 90 μm may be charged into the processing container as long as the conditions are satisfied. However, since the heavy rare earth element RH is a rare metal and a reduction in the amount used is required, it is preferable not to use a plurality of alloy powder particles having a size of more than 90 μm. In addition, if the amount of alloy powder particles exceeding 90 μm is too large, the amount of RT-B-based sintered magnet material that can be processed at one time decreases, so the RTB-based sintered magnet material and alloy The powder particles (total of alloy powder particles having a size of 90 μm or less and more than 90 μm) are preferably loaded into the processing vessel in a weight ratio of 1: 0.02 to 2.

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

  In an embodiment of the present disclosure, a plurality of agitation assisting members, in which 65% or more of the entire agitation assisting members by weight ratio use the agitation assisting member of 0.5 mm or more and 4 mm or less . The diameter φ of the stirring assisting 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, as long as the stirring auxiliary member satisfies the above-mentioned 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), other than these, it is less than 0.5 mm or more than 4 mm. You may have the stirring auxiliary member which has a diameter. However, if the size is too large or too small, it may be difficult to handle in mass production, so the stirring assist member preferably has a diameter of 0.3 mm or more and 20 mm or less.

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

  The agitation assisting member preferably has a shape that facilitates movement in the processing container. Here, examples of the shape that is easy to move include a spherical shape and a cylindrical shape. The stirring assisting member is preferably made of a material that is difficult to react even when coming into contact with the RTB-based sintered magnet material and the alloy powder particles during the RH supply diffusion process. As a material of the stirring assisting member, zirconia, silicon nitride, silicon carbide and boron nitride, or a ceramic of a mixture of these, etc. are preferable. It may be an element of a group including Mo, W, Nb, Ta, Hf, Zr, or a mixture of these.

[Step of performing RH supply diffusion processing]
The R-T-B system is obtained by heating and rotating and / or rocking a processing container in which a plurality of R-T-B sintered magnet materials and a plurality of alloy powder particles are charged in the above process. The heavy rare earth element RH is supplied from the alloy powder particles to the surface of the R-T-B based sintered magnet material by moving the sintered magnet material and the alloy powder particles continuously or intermittently. An RH supply diffusion process is performed to diffuse the heavy rare earth element RH inside the magnet. This makes it possible to _stably obtain high H _cJ while suppressing the decrease in B _r . 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. The method of using the device will be described based on FIG. First, the lid 5 of FIG. 2 is removed from the processing container 4 and a plurality of RTB-based sintered magnet materials 1, a plurality of alloy powder particles 2 and a plurality of stirring assisting members 3 are charged into the processing container 4 And attach the lid 5 to the processing container 4 again. The ratio of the loading amount of the RTB-based sintered magnet material 1, the alloy powder particle 2, and the stirring auxiliary member 3 is set to be within the above-described predetermined range.

  Next, the inside of the processing container 4 is evacuated and depressurized by the exhaust unit 6 (an Ar gas or the like may be introduced after depressurization). Then, while the processing container 4 is rotated by the motor 8, heating by the heater 7 is performed. The RH supply and diffusion process can be smoothly performed by uniformly stirring the R-T-B-based sintered magnet material 1, the alloy powder particles 2 and the stirring assisting member 3 as illustrated by the rotation of the processing container 4. 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 heat resistance of 1000 ° C. or higher, and the RTB-based sintered magnet material 1, alloy powder particles 2, and stirring assist Any material that does not easily react with any of the members 3 may 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, and the like may be used. The processing container 4 is provided with a lid 5 which can be opened and closed or removed. Further, protrusions may be provided on the inner wall of the processing container 4 so that the RTB-based sintered magnet material 1, the alloy powder particles 2 and the stirring assisting member 3 can be moved efficiently. Furthermore, the shape of the processing container 4 may be oval or polygonal in addition to circular. The processing container 4 is connected to the 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 so that 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 the heater 7 disposed on the outer peripheral portion thereof. A typical example of the heater 7 is a resistive heater that generates heat by current. By heating the processing container 4, the R-T-B-based sintered magnet material 1, the alloy powder particles 2, and the stirring assisting member 3 charged in the inside thereof are also heated. The processing container 4 is rotatably supported, and can be rotated by the motor 8 even during heating by the heater 7. As for the rotational speed of the processing container 4, it is preferable to set the circumferential speed of the inner wall surface of the processing container 4 to 0.1 m or more per minute, for example.

  In the present embodiment, the temperatures of the R-T-B-based sintered magnet material 1, the alloy powder particles 2 and the stirring assisting 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, which are relatively difficult to vaporize, to a high temperature of, for example, 1000 ° C. or higher. Therefore, a temperature (800 suitable for diffusing Dy and / or Tb into the R-T-B-based sintered magnet material 1 through the grain boundary phase of the R-T-B-based sintered magnet material 1 RH supply diffusion processing can be realized at a temperature of not less than ° C and not more than 1000 ° C.

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

  The alloy powder particle 2 is heated to a high temperature, and the Dy or Tb is actively vaporized from the alloy powder particle 2 to form a thick film of the heavy rare earth element RH on the surface of the R-T-B based sintered magnet material 1 In order to form H, 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 RH supply diffusion processing. Such heating can not be performed by the heater 7 located outside the processing container 4 and needs to be performed by, for example, induction heating in which microwaves are emitted only to the alloy powder particles 2. In that case, since it is necessary to place the alloy powder particle 2 at a position separated from the R-T-B-based sintered magnet material 1 and the stirring assisting member 3, as in the embodiment of the present disclosure, R-T The B-based sintered magnet material 1, the alloy powder particles 2 and the stirring assisting member 3 can not be stirred into the processing container 4.

  The inside of the processing container 4 at the time of heating is preferably in an inert atmosphere. The "inert atmosphere" in the present invention includes a vacuum or an inert gas atmosphere. In addition, “inert gas” is, for example, a rare gas such as argon (Ar), but chemically between the R-T-B based sintered magnet material 1 and the alloy powder particles 2 and the stirring assisting member 3 In the present invention, a gas which does not react is included in the "inert gas". The pressure in the processing container 4 is preferably 1 kPa or less.

  In the RH supply diffusion process of the present invention, the temperature of at least the RTB-based sintered magnet material 1 and the alloy powder particle 2 is preferably maintained in the range of 500 ° C. or more and 1000 ° C. or less, 800 ° C. or more and 1000 ° C. The following range is more preferable. In the above temperature range, the R-T-B-based sintered magnet material 1 and the alloy powder particles 2 relatively move in the processing container and while being close to or in contact with each other, the heavy rare earth element RH is R-T-B-based It is a preferable temperature range in which the grain boundary phase in the inside of the sintered magnet material is propagated to the inside through the grain boundary phase, and the diffusion of the heavy rare earth element RH into the inside of the RTB-based sintered magnet material is efficiently performed. . The holding time may be determined in consideration of the loading amount, shape, and the like of the RTB-based sintered magnet material 1, the alloy powder particles 2, and the stirring assisting member 3. The holding time is, for example, 10 minutes to 72 hours, preferably 1 hour to 14 hours. Moreover, although the process container 4 has shown the structure which rotates in FIG. 2, the process container 4 may be made to rock | fluctuate, and you may carry out the operation | movement of a rotation and a rocking movement together.

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

  The method of separating the R-T-B-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 or the like.

After the RH supply diffusion process, the RH diffusion process may be performed to diffuse the heavy rare earth element RH into the interior of the R-T-B-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 the heavy rare earth element RH diffuses deeply from the surface side of the RTB-based sintered magnet, and as a whole magnet It is possible to increase H _cJ . The RH diffusion process heats the RTB-based sintered magnet within the range of 700 ° C. or more and 1000 ° C. or less under the condition that the heavy rare earth element RH is not supplied from the alloy powder particles to the RTB-based sintered magnet. . The time of the RH diffusion process is, for example, 10 minutes to 72 hours. Preferably, it is 1 hour to 12 hours.

  Furthermore, after the RH supply diffusion treatment or after the RH diffusion treatment, heat treatment may be performed to improve the magnetic properties of the RTB-based sintered magnet. This heat treatment is the same as the heat treatment carried out after sintering in a known method of manufacturing a RT-B based sintered magnet. Known conditions may be adopted for the heat treatment atmosphere, the heat treatment temperature and the like.

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

Example 1
Using Nd metal, Pr metal, Dy metal, ferroboron alloy, electrolytic Co, Al metal, Cu metal, Ga metal and electrolytic iron (all metals have a purity of 99% or more). It mixes so that it may become the composition of RTB-based sintered magnet material of A, those materials are melted respectively and cast by strip casting method, flake-like material of thickness 0.2-0.4 mm Got an alloy. The obtained flake-like raw material alloy was subjected to hydrogen embrittlement in a hydrogen pressurized atmosphere, and then subjected to dehydrogenation treatment of heating and cooling in vacuum to 550 ° C. to obtain roughly crushed powder. Next, 0.04 parts by mass of zinc stearate as a lubricant is added to 100 parts by mass of the roughly pulverized powder and mixed with the roughly pulverized powder thus obtained, and then it is dry-milled in a nitrogen stream using a jet mill apparatus. Thus, a finely pulverized powder with a particle size D ₅₀ of 4 μm was obtained. The particle diameter D ₅₀ is the volume-based median diameter obtained by laser diffraction method using a stream of the dispersion equation.

To the finely pulverized powder, 0.05 parts by mass of zinc stearate as a lubricant was added and mixed with 100 parts by mass of the finely pulverized powder, followed by molding in a magnetic field to obtain a molded body. As a 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 is sintered at 1070 ° C. for 4 hours in vacuum, and the raw material No. 1 is sintered. The 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. The analysis results of the components of the obtained RTB-based sintered magnet material are shown in Table 1. Each component in Table 1 was measured using high frequency inductively coupled plasma emission spectrometry (ICP-OES). In addition, O (oxygen content), gas melting-infrared absorption method, N (nitrogen content), gas melting-heat conduction method, C (carbon content), using a gas analyzer by combustion-infrared absorption method Measured. The resulting 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. Further, eight corners of the RTB-based sintered magnet are chamfered with a radius of 1.0 mm.

Next, a raw material alloy was prepared by using Tb metal and electrolytic iron so as to be TbFe ₃ (Tb 48.7 mass%, Fe 51.3 mass%). Casting and casting to dissolve these raw alloy was prepared flaky TbFe ₃ alloy thickness 0.2 to 0.4 mm. The resulting TbFe ₃ alloy was pin mill pulverizing, by sieving with JIS standard shown in Table 2, No. A to g of a plurality of alloy powder particles were prepared. More specifically, for alloy powder particle No. 1 in Table 2, a is an alloy powder particle which did not pass through a sieve of 212 micrometers which sieved a plurality of pin milled alloy powder particles through a sieve of 1000 micrometers, and then passed through a sieve of 1000 micrometers through a sieve of 212 micrometers. In addition, alloy powder particle no. g is an alloy powder particle that has passed through a 38 μm sieve. Alloy powder particle no. bf, Table 5 and Table 7 are described similarly. Furthermore, a plurality of zirconia balls having a diameter of 3 mm were prepared as a stirring aid member.

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

Table 3 shows the measurement results of the magnetic properties of the obtained RTB-based sintered magnet. The values of B _r and H _cJ shown in Table 3 are measured by a BH tracer by machining the entire surface of the _RTB -based sintered magnet after heat treatment to make the sample 5 mm (M) x 7 mm x 7 mm did. Sample No. in Table 3 1 is alloy powder No. 1; a and RTB-based sintered magnet materials No. A is used to perform RH supply diffusion processing. Sample No. 2-7 are described similarly.

As shown in Table 3, 3% by weight ratio of alloy powder particles having a size of 90 μm or less is charged in a treatment container to a sintered RTB based magnet material, and the treatment container is heated and rotated. The RTB-based sintered magnet (samples Nos. 4 to 7) in the embodiment of the present invention subjected to the RH supply and diffusion treatment is R- of the comparative example using alloy powder particles having a size exceeding 90 μm. Higher H _cJ is obtained as compared to the T-B based sintered magnets (samples Nos. 1 to 3). Also, if the 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), but stable to be within the scope of the invention it is possible (as in sample No.4~7, H _cJ variation in the range of 1920kA / m~2014kA / m is small) obtain high H _cJ. In addition, as shown in Table 3, the size is 38 μm or more and 75 μm or less (samples No. 5 and 6 in the embodiment of the present invention) more stably and high H _cJ is obtained, and the size is further smaller. Higher _HcJ is obtained in the _{range of} 38 μm or more and 63 μm or less (Sample No. 6 of the present invention).

  Moreover, the obtained sample No. The chipping of 1 to 7 RTB-based sintered magnets was evaluated. For evaluation of chipping, 20 pieces of R-T-B sintered magnets were taken out, and the number ratio of R-T-B-based sintered magnets having a chip size equal to or larger than the volume of a sphere of 1 mm in diameter was counted The incidence rate of chipping is evaluated as 10% or less according to the present invention. Sample No. When 20 pieces of 1 to 7 RTB-based sintered magnets were drawn out and evaluation of chipping was conducted, all samples were within the range of the present invention (the incidence of chipping is 10% or less) .

Example 2
In the same manner as in Example 1, the material No. 1 is obtained. An RTB-based sintered magnet material of A was prepared. Then prepared TbFe ₃ alloy in the same manner as in Example 1, by multiplying the 90 [mu] m sieve and a pin mill pulverizing (JIS standard), were prepared following plurality of alloy powder particles 90 [mu] m. Furthermore, a plurality of zirconia balls having a diameter of 3 mm were prepared as a stirring aid member.

  The alloy powder particles, the RTB-based sintered magnet material, and the stirring auxiliary member were loaded into the processing container shown in FIG. The weight ratio of the alloy powder particles to the RTB-based sintered magnet material is shown in Table 4. In Table 4, for example, sample no. 8 shows that the alloy powder particles were charged at 1% by weight ratio to the RTB-based sintered magnet material. Sample No. 9 to 19 are described in the same manner. The RH supply diffusion process was performed in the same manner as in Example 1 except that the alloy powder particles were charged into the processing vessel at a weight ratio shown in Table 4. Furthermore, 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. The values of B _r and H _cJ shown in Table 4 were measured by the same method as in Example 1.

As shown in Table 4, the R-T-B of the present invention obtained by charging the alloy powder particles in a proportion by weight of 2% to 15% with respect to the R-T-B sintered magnet material The sintered sintered magnet (samples No. 9 to 14) has a weight ratio higher than that of the R-T-B sintered magnet (samples No. 8 and 15 to 19) of the comparative example whose weight ratio is out of the range H _cJ has been obtained. Furthermore, as shown in Table 4, the weight ratio of the alloy powder particles to the _RTB -based sintered magnet material is 3% or more and 7% or less (samples _{Nos. 10} to 12), in which H _cJ is higher. It is obtained. Moreover, the obtained sample No. When the chip of the RTB-based sintered magnet of 8 to 19 was evaluated under the same conditions as in Example 1, all the samples were within the range of the present invention (the incidence of chipping is 10% or less).

Example 3
In the same manner as in Example 1, the material No. 1 is obtained. A plurality of lots of RTB based sintered magnet materials of A were prepared. Then prepared TbFe ₃ alloy in the same manner as in Example 1, by sieving with JIS standard shown in Table 5 by a pin mill pulverizing, No. Several lots of alloy powder particles h to j were prepared. Furthermore, a plurality of zirconia balls having a diameter of 3 mm were prepared as a stirring aid member.

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

Table 6 shows the measurement results of the magnetic properties of the obtained RTB-based sintered magnet. The values of B _r and H _cJ shown in Table 6 were measured by the same method as in Example 1.

As shown in Table 6, the RTB-based sintered magnet of the present invention (Sample No. 1) was obtained even when the RH supply and diffusion process was repeated using alloy powder particles that had been subjected to the RH supply and diffusion process once. In the samples 21 and 22), a high _HcJ is obtained as compared with the _RTB -based sintered magnet (sample No. 20) of the comparative example using alloy powder particles having a size of more than 90 μm. Moreover, stable as being within the scope of the present invention (1881kA / m and 1890kA / m) high H _cJ are achieved. Moreover, the obtained sample No. When the chip of the RTB-based sintered magnet of 20 to 22 was evaluated under the same conditions as in Example 1, all the samples were within the range of the present invention (the incidence of chipping is 10% or less).

Example 4
A plurality of R-T-B sintered magnet materials and a plurality of alloy powder particles h to j are prepared in the same manner as in Example 3, and a plurality of RH supply diffusion treatments are performed in the same manner as in Example 3. I went for a minute. Then, the alloy powder particles of each lot remaining after RH supply diffusion are collected, subjected to pin mill grinding (grind to such an extent that the alloy powder particles do not become too small), and again passed through a sieve according to JIS standard shown in Table 7. Several alloy powder particles of h'-j 'were prepared. When the alloy powder particles (h 'to j') are observed by a field emission scanning electron microscope (FE-SEM), foreign matter other than the RH diffusion source (for example, R oxide or RTB) is observed on the surface. It was confirmed that there was a portion where the compound was not present (a portion where the nascent surface was exposed was confirmed). Furthermore, a plurality of zirconia balls having a diameter of 3 mm were prepared as a stirring aid member.

  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 process was performed in the same manner as in Example 1 using the auxiliary member. Furthermore, heat treatment was performed in the same manner as in Example 1.

Table 8 shows the results of measuring the magnetic properties of the obtained RTB-based sintered magnet. The values of B _r and H _cJ shown in Table 8 were measured by the same method as in Example 1.

As shown in Table 8, the R-T-B-based sintered magnet of the present invention (No. 24) according to the present invention in which the alloy powder particles after RH supply diffusion treatment are ground to expose the nascent surface to at least a part of the alloy powder particles. And 25) are even higher compared to the RTB based sintered magnet (Nos. 21 and 22) of the present invention of Example 3 in which the nascent surface is not exposed to at least a part of the alloy powder particles. H _cJ has been obtained. Moreover, the obtained sample No. When the chip of the RTB-based sintered magnet of 23 to 25 was evaluated under the same conditions as in Example 1, all samples were within the range of the present invention (the incidence of chipping is 10% or less).

Example 5
In the same manner as in Example 1, the material No. 1 is obtained. A plurality of lots of RTB based sintered magnet materials of A were prepared. Next, using Tb metal and electrolytic iron, alloy powder No. 1 in Table 9 is used. The alloys were prepared in the same manner as in Example 1 by blending so as to have the compositions shown in w-1 to w-5. The obtained alloy was subjected to pin mill pulverization and applied to a sieve of 90 μm (JIS standard) to prepare a plurality of alloy powder particles of 90 μm or less (alloy powders No. w-1 to w-5). . Furthermore, a plurality of zirconia balls having a diameter of 3 mm were prepared as a stirring aid member.

  Next, RH supply diffusion processing was performed under the same conditions as 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. Furthermore, heat treatment was performed in the same manner as in Example 1. The magnetic properties of the resulting RTB-based sintered magnet were measured in the same manner as in Example 1. The measurement results are shown in Table 10. 26-30. Sample No. in Table 10 No. 26, alloy powder No. w-1 and RTB sintered magnet materials No. 1 A is used to perform RH supply diffusion processing. Sample No. 27-30 are described similarly.

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

Example 6
In the same manner as in Example 1, the material No. 1 is obtained. An RTB-based sintered magnet material of A was prepared. Was prepared TbFe ₃ alloy and then at the same manner as in Example 1. It was then prepared a plurality of alloy powder particles by performing a hydrogen pulverization against TbFe ₃ alloy. Hydrogen pulverization is carried out by first charging TbFe ₃ into the hydrogen furnace, then starting the hydrogen supply into the hydrogen furnace at room temperature, and performing a hydrogen storage process for 90 minutes maintaining the absolute pressure of hydrogen at about 0.3 MPa. The In this process, hydrogen in the furnace is consumed along with the hydrogen storage reaction of the alloy powder, and the pressure of hydrogen is reduced. Therefore, additional hydrogen is supplied to control the reduction to about 0.3 MPa.

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

  The same method as in Example 1 using a plurality of the alloy powder particles after the hydrogen grinding, the RTB-based sintered magnet material, and the stirring auxiliary member without classification using a sieve with an opening of 90 μm The RH supply diffusion process was performed. Furthermore, heat treatment was performed in the same manner as in Example 1. In addition, when a plurality of alloy powder particles after hydrogen pulverization were sieved with a 90 μm for confirmation, they 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 resulting RTB-based sintered magnet were measured in the same manner as in Example 1. The measurement results are shown in Table 11.

As shown in Table 11, in the case of obtaining a plurality of alloy powder particles by performing hydrogen grinding, heating is performed at 400 ° C. or more and 550 ° C. or less in the dehydrogenation step (dehydrogenation temperature is 400 ° C. or more and 550 ° C. or less The invention (samples Nos. 32 to 34) subjected to hydrogen grinding all gave high _HcJ . Moreover, stable as being within the scope of the invention (1998kA / m~2013kA / m) high H _cJ are achieved. On the other hand, sample No. 1 whose dehydrogenation heat temperature is out of the range of the present invention. In No. 31 and 35, the magnetic characteristics could not be measured because the RTB-based sintered magnet was hydrogen-embrittled after the RH supply diffusion treatment. This is because, as shown in Table 11, the hydrogen content of the plurality of alloy powder particles (samples No. 32 to 34) manufactured under the hydrogen pulverizing conditions of the present invention is several tens ppm and almost no hydrogen remains. On the other hand, the hydrogen content of several alloy powder particles (samples No. 31 and 35) whose dehydrogenation temperature is out of the range of the present invention is as large as several hundreds ppm and hydrogen remains. Therefore, since hydrogen is supplied from the plurality of alloy powder particles to the R-T-B-based sintered magnet material during RH supply diffusion processing, the finally obtained R-T-B-based sintered magnet is hydrogen It is considered to be embrittled. Moreover, the obtained sample No. When the chipping of the RTB-based sintered magnet of 32-34 was evaluated under the same conditions as in Example 1, all the samples were within the range of the present invention (the incidence of chipping is 10% or less).

Reference Example 1
In the same manner as in Example 1, the material No. 1 is obtained. An RTB-based sintered magnet material of A was prepared. Then prepared a pin mill pulverizing the TbFe ₃ alloy in the same manner as in Example 1 and sieved with 63 .mu.m, then to the alloy powder particles through the sieve of 63 .mu.m did not pass the sieve of 38μm sieved with 38μm alloy Powder particles were prepared. The said alloy powder particle of 3% with respect to the weight of the RTB type | system | group sintered magnet raw material was prepared, and the turbid liquid which mixed the prepared said alloy powder particle with alcohol with a mass fraction of 50% was prepared. The turbid solution was applied to the surface (entire surface) of the RTB-based sintered magnet material and dried with warm air.

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

  The magnetic properties of the resulting RTB-based sintered magnet were measured in the same manner as in Example 1. The measurement results are shown in Table 12.

The reference example 1 is not the RH supply diffusion process of the present invention, but the RH supply diffusion process is performed by the method described in Patent Document 2. The sample numbers in Table 9 Sample No. 36 is the same as sample No. 1 of Example 1 except that the RH supply diffusion process is different. It is produced by the same composition and method as No. 6. As shown in Table 12, sample nos. 36 is the sample No. H _cJ is significantly reduced compared to 6. That is, in the RH supply diffusion process described in Patent Document 2, the alloy powder particle of the specific size of the present invention is used, and the charging amount of the alloy powder particle of the specific size is R-T-B based sintering Even high H _cJ can not be obtained as a specific ratio of the present invention to the weight ratio of the magnet material.

Example 7
In the same manner as in Example 1, the material No. 1 is obtained. An RTB-based sintered magnet material of A was prepared. Then prepared TbFe ₃ alloy in the same manner as in Example 1, by multiplying the 90 [mu] m sieve and a pin mill pulverizing (JIS standard), were prepared following plurality of alloy powder particles 90 [mu] m. In addition, a plurality of zirconia balls having a diameter of 1 to 7 mm were prepared as a stirring assisting member.

  An RH supply diffusion process was performed using the alloy powder particles, the RTB-based sintered magnet material, and the stirring auxiliary member. RH supply diffusion processing performed RH supply diffusion processing by the same method as Example 1 except using the stirring auxiliary member of the magnitude | size shown in Table 13. Sample No. in Table 13 41 is the same method as in Example 1 except that 70% of the total of a plurality of stirring assistants in weight ratio is using a 2 mm diameter stirring assistant and 30% is using a 7 mm diameter stirring assistant. RH supply diffusion processing was performed. Sample No. 37-40 and 42, 43 are likewise described. Furthermore, heat treatment was performed in the same manner as in Example 1.

  The magnetic properties of the resulting RTB-based sintered magnet were measured in the same manner as in Example 1. The measurement results are shown in Table 13. Moreover, the obtained sample No. The chipping of the RTB based sintered magnet of 37 to 43 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 incidence of chipping is 10% or less), it is described as ○, and when it is outside the range (the incidence of chipping is more than 10%), it is described as ×. .

  As shown in Table 13, the present invention (Sample Nos. 37 to 39) in which 65% or more of the stirring aid members in the weight ratio by weight ratio have a size of 0.5 mm or more and 4 mm or less. 41, and 43) were all within the scope of the present invention (the incidence of chipping was 10% or less). On the other hand, when the size of the stirring assisting member was out of the range of the present invention (samples No. 40 and 42), many chips occurred.

  According to the present invention, an RTB-based sintered magnet having a high residual magnetic flux density and a high coercive force can be manufactured. The sintered magnet of the present invention is suitable for various motors such as a motor for hybrid vehicle mounting exposed to high temperature, home appliances, and the like.

1 RTB-based sintered magnet material 2 alloy powder particle 3 stirring auxiliary member 4 processing vessel 5 lid 6 exhaust device 7 heater 8 motor

Claims (12)

Several R-T-B sintered magnet materials (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 necessarily includes Fe. Step of preparing
Preparing a plurality of alloy powder particles having a size of 90 μm or less, containing 20 to 80 mass% of heavy rare earth element RH (heavy rare earth element RH is at least one of Tb and Dy);
Preparing a plurality of agitation assisting members, wherein the agitation assisting members having a weight ratio of at least 65% of the total agitation assisting members have a diameter of 0.5 mm or more and 4 mm or less;
The plurality of RTB-based sintered magnet materials, and the alloy powder particles having a weight ratio of 2% to 15% with respect to the plurality of RTB-based sintered magnet materials, 100% or more and 500% or less by weight ratio with respect to a plurality of RTB-based sintered magnet materials;
The R-T-B-based sintered magnet material, the alloy powder particles, and the stirring auxiliary member are moved continuously or intermittently by heating and rotating and / or rocking the processing container to thereby rotate the RH. Performing a supply diffusion process;
The manufacturing method of the RTB-based sintered magnet containing   The manufacturing method of the RTB-type sintered magnet of Claim 1 which heats the said processing container to the processing temperature of 800 degreeC or more and 1000 degrees C or less in the process of performing the said RH supply diffusion process.   The method of manufacturing an RTB-based sintered magnet according to claim 1, wherein the size of each of the plurality of alloy powder particles is 38 μm or more and 75 μm or less.   The weight ratio with respect to the said RTB type | system | group sintered magnet raw material of several said alloy powder particle | grains charged in the said processing container is 3%-7% in any one of Claim 1 to 3 The manufacturing method of the RTB-based sintered magnet.   5. The R-T-B-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 in part. Production method.   The method for manufacturing an RTB-based sintered magnet according to any one of claims 1 to 5, wherein the plurality of alloy powder particles contain the heavy rare earth element RH in a range of 35% by mass to 65% by mass.   The method for producing an R-T-B-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 the maximum size of three sizes in three orthogonal directions is twice or more the minimum size. The manufacturing method of the RTB-based sintered magnet according to any one of 1 to 7.   Each of the plurality of sintered magnet materials has a shape of a rectangular solid having a length of 40 mm or more on one side and a length of 10 mm or less on the other 2 sides, or a shape of a substantially rectangular solid chamfered at each vertex position The manufacturing method of the RTB-type sintered magnet of Claim 8 which has these.   10. The R-T- according to any one of claims 1 to 9, wherein each of the plurality of stirring assisting members is formed of a ceramic of zirconia, silicon nitride, silicon carbide, boron nitride, or a mixture thereof. Method of producing a B-based sintered magnet   The R-T-B-based sintered magnet material to which the heavy rare earth element RH is supplied from any of the plurality of alloy powder particles in the step of the RH supply diffusion process is in a non-contact state with the alloy powder particles The manufacturing method of the RTB-based sintered magnet according to any one of claims 1 to 10, comprising the step of heating to perform RH diffusion processing.   The plurality of alloy powder particles are produced by hydrogen-pulverizing an alloy containing heavy rare earth element RH (heavy rare earth element RH is Tb and / or Dy) in an amount of 35% by mass to 50% by mass. The method for producing an RTB-based sintered magnet according to any one of claims 1 to 11, wherein the alloy is heated to 400 ° C to 550 ° C in the dehydrogenation step.

Images