Diffusion source powder and method for producing rare earth sintered magnet

Abstract

The technical problem to be solved by the present invention is to provide a diffusion source powder that can be uniformly adhered to the surface of a rare earth sintered magnet. According to the technical scheme for solving the technical problem, the manufacturing method of the diffusion source powder comprises the steps of preparing a rare earth alloy melt; and a step for forming a plurality of atomized powder particles from the melt heated to a temperature of 1100-1400 DEG C (inclusive) by an atomization method. And the rare earth alloy is R-M-A alloy. R includes at least one rare earth element and includes at least one of Nd and Pr. M is selected from at least one of Cu, Ga, Co and Fe. A represents at least one element selected from the group consisting of Al, Si, Ti, V, Cr, Mn, Co, Ni, Zn, Ge, Zr, Nb, Mo, Ag, and B.

Description

Technical Field

[0001] The present invention relates to a diffusion source powder and a method for producing a rare earth system sintered magnet using the diffusion source powder. Background Art

[0002] R2T 14 RTB sintered magnets with B-type compounds (R contains at least one rare earth element and contains at least one of Nd and Pr, and T is Fe or Fe and Co) as the main phase are well-known as the highest performance magnets among permanent magnets. They are used in various motors and home appliances such as voice coil motors (VCM) for hard disk drives and load-bearing motors for hybrid vehicles.

[0003] RTB sintered magnets have an intrinsic coercive force H at high temperatures. cJ (hereinafter referred to as "H cJ ”) decreases, thus causing irreversible thermal demagnetization. In order to avoid irreversible thermal demagnetization, it is required to maintain a high H even at high temperatures when used in motor applications, etc. cJ .

[0004] It is known that in RTB-based sintered magnets, heavy rare earth elements RH (Dy, Tb) are used to replace R2T 14 When part R in the B-type compound phase, H cJ To obtain high H at high temperature cJ It is effective to add a large amount of heavy rare earth elements RH to RTB based sintered magnets. However, in RTB based sintered magnets, when heavy rare earth elements RH are used to replace light rare earth elements RL (Nd, Pr), H cJ On the other hand, there is a residual magnetic flux density B r (hereinafter referred to as "B r ”) to reduce such problems. In addition, the heavy rare earth element RH is a rare resource, so it is necessary to reduce its usage.

[0005] Therefore, in recent years, the r Using less heavy rare earth element RH to increase the H of RTB sintered magnets cJ For example, it is proposed to allow fluoride or oxide of heavy rare earth element RH, or various metals M or M alloys to exist on the surface of sintered magnets alone or in mixture, and to perform heat treatment in this state, thereby diffusing heavy rare earth element RH that helps to increase coercive force into the magnet.

[0006] Patent Document 1 discloses the use of powders of R oxide, R fluoride, and R oxyfluoride (R is a rare earth element).

[0007] Patent Document 2 discloses the use of RM (M is one or more selected from Al, Cu, Zn, Ga, etc.) alloy powder.

[0008] Patent documents 3 and 4 disclose that by using a mixed powder of RM alloy (M is one or more selected from Al, Cu, Zn, Ga, etc.), M1M2 alloy (M1M2 is one or more selected from Al, Cu, Zn, Ga, etc.) and RH oxide, the RM alloy can be used to partially reduce the RH oxide during heat treatment and the heavy rare earth element RH can be introduced into the magnet.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: International Publication No. 2006 / 043348

[0012] Patent Document 2: Japanese Patent Application Publication No. 2008-263179

[0013] Patent Document 3: Japanese Patent Application Publication No. 2012-248827

[0014] Patent Document 4: Japanese Patent Application Publication No. 2012-248828

[0015] Patent Document 5: International Publication No. 2015 / 163397 Summary of the invention

[0016] Technical problem to be solved by the invention

[0017] The above-mentioned patent documents 1 to 4 disclose methods of causing a mixed powder containing RH compound powder to be present on the entire surface of a magnet (the entire surface of the magnet) and then subjecting it to heat treatment. According to specific examples of these methods, the mixed powder is dispersed in water or an organic solvent to form a slurry, and the magnet is immersed in the slurry and pulled (immersion pulling method). In the case of the immersion pulling method, the magnet pulled from the slurry is dried with hot air or naturally dried. It is also disclosed that the slurry is sprayed onto the magnet (spraying method) instead of immersing the magnet in the slurry.

[0018] In these methods, the slurry can be applied to the entire surface of the magnet. Therefore, the heavy rare earth element RH can be introduced into the magnet from the entire surface of the magnet, which can further increase the RH content after heat treatment. cJ However, in the immersion pulling method, the slurry will always be biased toward the lower part of the magnet due to gravity. In addition, in the spraying method, the coating thickness at the end of the magnet becomes thicker due to surface tension. It is difficult to make the RH compound uniformly present on the surface of the magnet by any method.

[0019] When using a low viscosity slurry to thin the coating layer, the unevenness of the coating layer thickness can be improved to a certain extent. However, since the amount of slurry applied is reduced, the H after heat treatment cannot be greatly improved. cJ When multiple coatings are performed to increase the amount of slurry applied, production efficiency is significantly reduced. In particular, when the spraying method is used, the slurry is also applied to the inner wall surface of the spraying device, and the utilization yield of the slurry is reduced. As a result, there is a problem of wasting the heavy rare earth element RH, which is a rare resource.

[0020] The present applicant disclosed in Patent Document 5 a method of performing diffusion heat treatment in a state where RLM alloy powder and RH fluoride powder are present on the surface of an RTB-based sintered magnet. It cannot be said that a method of making these powders uniformly present on the surface of an RTB-based sintered magnet has not yet been fully established. In particular, when the particle size of the diffusion source powder is non-uniform, the surface density of the diffusion source powder attached to the surface of the sintered magnet also becomes non-uniform, making it difficult to achieve uniform diffusion.

[0021] The present invention provides a diffusion source powder having high uniformity of particle size suitable for diffusing various elements into a rare earth system sintered magnet, and a method for producing a rare earth system sintered magnet capable of diffusing desired elements from the surface to the inside of the magnet by using the diffusion source powder.

[0022] Technical solutions for solving technical problems

[0023] In one embodiment, the method for manufacturing a diffusion source powder of the present invention is a method for manufacturing a diffusion source powder containing a plurality of atomized powder particles formed of a rare earth alloy, the manufacturing method comprising: a step of preparing a molten solution of the rare earth alloy; and a step of forming a plurality of atomized powder particles from the molten solution heated to a temperature of 1100° C. to 1400° C. by an atomization method. The rare earth alloy is an RMA alloy. R contains at least one rare earth element and contains at least one of Nd and Pr. M is at least one selected from Cu, Ga, Co and Fe. A is at least one selected from Al, Si, Ti, V, Cr, Mn, Co, Ni, Zn, Ge, Zr, Nb, Mo, Ag and B.

[0024] In one embodiment, the diffusion source powder of the present invention is a diffusion source powder containing a plurality of atomized powder particles formed of a rare earth alloy, wherein the rare earth alloy is an RMA alloy. R contains at least one rare earth element and contains at least one of Nd and Pr. M is at least one selected from Cu, Ga, Co and Fe. A is at least one selected from Al, Si, Ti, V, Cr, Mn, Co, Ni, Zn, Ge, Zr, Nb, Mo and Ag. More than half of the particles of the plurality of atomized powder particles each have a concave portion.

[0025] In a certain embodiment, the manufacturing method of the rare earth sintered magnet of the present invention includes: a process of preparing the above-mentioned diffusion source powder; a process of preparing a rare earth sintered magnet raw material having a bonding layer provided on at least a portion of the surface; a process of making the above-mentioned diffusion source powder adhere to the above-mentioned bonding layer of the above-mentioned rare earth sintered magnet raw material; and a process of heating the above-mentioned rare earth sintered magnet raw material to diffuse the elements contained in the above-mentioned diffusion source powder from the above-mentioned diffusion source powder adhered to the above-mentioned bonding layer into the interior of the above-mentioned rare earth sintered magnet raw material.

[0026] Effects of the Invention

[0027] The embodiments of the present invention can provide a diffusion source powder with high uniformity of particle size suitable for diffusing various elements into a rare earth sintered magnet, and can also provide a method for manufacturing a rare earth sintered magnet by diffusing a desired element from the surface to the inside of the magnet using the diffusion source powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a cross-sectional view schematically showing diffusion source powder particles adhering to a rare earth system sintered magnet material according to a conventional example.

[0029] Figure 2A This is another cross-sectional view schematically showing diffusion source powder particles adhering to a certain rare earth system sintered magnet material according to a conventional example.

[0030] Figure 2B This is a cross-sectional view schematically showing conventional diffusion source powder particles attached to other rare earth system sintered magnet materials.

[0031] Figure 3 This is a flowchart showing a method for producing diffusion source powder according to an embodiment of the present invention.

[0032] Figure 4 It is a graph showing the particle size distribution (solid line) of the powder produced by spraying a molten metal at 1300°C in the step (S2) of forming atomized powder particles in the present embodiment and the particle size distribution (dashed line) of the powder produced by spraying a molten metal at 750°C in the step of forming atomized powder particles in the prior art.

[0033] Figure 5 This is a diagram showing an example of an electron microscope photograph of a plurality of particles constituting the diffusion source powder of the present embodiment.

[0034] Fig. 6A This is a cross-sectional view schematically showing diffusion source powder particles according to the present embodiment attached to a rare earth system sintered magnet material.

[0035] Figure 6BThis is a cross-sectional view schematically showing diffusion source powder particles according to the present embodiment attached to other rare earth system sintered magnet materials.

[0036] Figure 7 This is a diagram schematically showing an example of a general configuration of a diffusion source adhering device 1000 according to the present embodiment.

[0037] Figure 8 It is a three-dimensional diagram schematically showing a flow tank and the wire located above it.

[0038] Fig. 9 This is a perspective view showing a state where a plurality of rare earth system sintered magnet raw materials are carried on a wire and transported in the Y-axis direction.

[0039] Fig.10 It is a cross-sectional view schematically showing the flow tank 100 and the wire 20 located thereon.

[0040] Fig.11 This is a cross-sectional view showing a state in which a plurality of rare earth system sintered magnet raw materials 10 are conveyed in the Y-axis direction by the wire rod 20 in a state in which the diffusion source powder in the flow channel 100 begins to flow.

[0041] Fig.12 1 is a flow chart showing a method for producing a rare earth system sintered magnet according to the present embodiment.

[0042] Explanation of symbols

[0043] 10: Rare earth sintered magnet raw material; 12: Adhesive layer; 14: Diffusion source powder; 14P: Atomized powder particles; 14X: Concave portion of atomized powder particles; 20: Wire; 30: Recovery portion; 100: Flow trough; 200: Conveying device; 300: Flow trough storage chamber; 400: Circulation mechanism; 500: Diffusion source powder supply device; 600: Control device; 1000: Diffusion source attachment device. DETAILED DESCRIPTION

[0044] The present invention provides a diffusion source powder containing a plurality of atomized powder particles formed of a rare earth alloy and a method for producing the same.

[0045] Atomized powder particles are manufactured by atomization. When the molten metal or alloy flows out from a small opening provided at the bottom of the crucible and is sprayed and scattered toward a high-speed fluid or a rotating disk, powder particles of the metal or alloy that are rapidly solidified can be formed. Such a powder manufacturing method is called an atomization method, and the powder manufactured by the atomization method is called an atomized powder. Among them, the particles constituting the atomized powder are sometimes called atomized powder particles.

[0046] Atomized powder particles are different from powder particles produced by mechanically crushing an ingot of a metal or alloy, and have a roughly spherical shape. In addition, the distribution of particle sizes (particle diameters) contained in the atomized powder is sharper than the particle size distribution of the mechanically crushed powder. Therefore, the diffusion source powder containing a plurality of atomized powder particles formed of a rare earth alloy is more suitable for achieving uniform diffusion than the diffusion source powder containing powder particles formed by mechanically crushing a rare earth alloy.

[0047] However, according to the research of the inventors of the present invention, when using the diffusion source powder produced by the conventional atomization method, the surface density of the diffusion source powder attached to the surface of the sintered magnet raw material is sometimes uneven, making it difficult to achieve uniform diffusion. The inventors of the present invention have conducted careful research and found that the reason is that the particle size uniformity of the diffusion source powder produced by the conventional atomization method is not necessarily sufficient.

[0048] Figure 1 The figure is a cross-sectional view schematically showing an atomized powder particle 14P of a conventional example of a diffusion source powder 14 attached to a rare earth system sintered magnet raw material (workpiece) 10. Hereinafter, for the sake of simplicity, the atomized powder particle 14P is sometimes referred to as "particle 14P". In this example, an adhesive layer (adhesive) 12 is provided on the surface of the rare earth system sintered magnet raw material 10. The particle 14P is attached to the adhesive layer 12 by a diffusion source attachment device described later. By using such a diffusion source attachment device, as Figure 1 As shown, the particles 14P can be attached to the bonding layer 12 of the rare earth sintered magnet raw material 10 with a thickness of about one layer. When the size (particle diameter) of the attached particles 14P greatly varies depending on the position, the number and concentration of elements diffused from the particles 14P at each position into the rare earth sintered magnet raw material 10 will become different during the diffusion process.

[0049] In addition, in the diffusion source attachment device described later, the particles 14P of the diffusion source powder 14 suspended in the flow tank are attached to the bonding layer 12 of the rare earth system sintered magnet raw material 10. Therefore, when the particle size distribution of the diffusion source powder supplied to the flow tank has a large span, depending on the time point of attachment, the rare earth system sintered magnet raw material 10 mainly attached with particles 14P with relatively large particle sizes and the rare earth system sintered magnet raw material 10 mainly attached with particles 14P with relatively small particle sizes are produced. For example, at a certain time point in the attachment process, such as Figure 2A As shown, relatively small particles 14P of the diffusion source powder 14 are attached to the bonding layer 12 of the rare earth system sintered magnet raw material 10. At other time points, such as Figure 2BAs shown, relatively large particles 14P of the diffusion source powder 14 may be attached. In this case, the particle size of the particles 14P attached to the rare earth system sintered magnet raw material 10 will vary greatly in each manufacturing process, so the amount of elements diffused from the diffusion source powder 14 to the rare earth system sintered magnet raw material 10 changes, and as a result, the magnetic properties of each rare earth system sintered magnet vary greatly.

[0050] According to the embodiment of the present invention, the diffusion source powder 14 having a sharp particle size distribution can be produced, and thus such technical problems can be solved.

[0051] like Figure 3 As shown, the method for manufacturing diffusion source powder of this embodiment includes: a step of preparing a rare earth alloy melt (S1); and a step of forming a plurality of atomized powder particles from the melt heated to a temperature of 1100° C. to 1400° C. by an atomization method (S2).

[0052] The rare earth alloy is an RMA alloy. Among them, R contains at least one rare earth element and contains at least one of Nd and Pr. M is at least one selected from Cu, Ga, Co and Fe. A is at least one selected from Al, Si, Ti, V, Cr, Mn, Co, Ni, Zn, Ge, Zr, Nb, Mo, Ag and B. A is not an element required for the RMA alloy. In the case where the RMA alloy does not contain A, the RMA alloy can be recorded as "RM alloy", but in the present invention, it is recorded as "RMA alloy" in order to adopt a unified form of expression. In a preferred embodiment, A is at least one selected from Al, Si, Ti, V, Cr, Mn, Co, Ni, Zn, Ge, Zr, Nb, Mo and Ag. Among them, each group of M and A contains a repeated element (Co), but in the case where one of M and A selects the repeated element, the other is no longer repeatedly selected.

[0053] In one embodiment, the composition ratio of R is 65 mass % to 95 mass % of the entire RMA alloy, the composition ratio of M is 5 mass % to 35 mass % of the entire RMA alloy, and the composition ratio of A is 0 mass % to 3 mass % of the entire RMA alloy.

[0054] The total composition ratio of Nd and Pr is 60 mass % or more of the whole R. M contains at least one of Cu and Ga. The total composition ratio of Cu and Ga is 50 mass % or more of the whole M. The step (S2) of forming atomized powder particles includes a step of spraying the above-mentioned molten metal, and the temperature of the above-mentioned molten metal is adjusted to a range of 1100°C to 1400°C (preferably 1250°C to 1350°C).

[0055] Figure 4 The graph shows the particle size distribution (solid line) of the powder produced by spraying a molten metal at 1300°C in the step (S2) of forming atomized powder particles in the present embodiment and the particle size distribution (dashed line) of the powder produced by spraying a molten metal at 750°C in the step of forming atomized powder particles in the prior art. The particle size distribution is a frequency distribution, which is a value obtained by differentiating the cumulative distribution by the particle size. Figure 4 The vertical axis represents the frequency, and the horizontal axis represents the particle size.

[0056] according to Figure 4 It is clear that, with this embodiment, the particle size distribution is sharper than that of the prior art, and the span of the particle size distribution is narrower. This means that the deviation of the particle size is reduced. More specifically, the tailing of the relatively small side of the particle size that is significant when the melt is ejected at 750°C is reduced when the melt is ejected at 1300°C. One of the reasons for this is that by increasing the melt temperature, the viscosity of the melt is reduced when the melt is ejected, and the stability of the melt when the melt is ejected is increased.

[0057] By using this embodiment, it is possible to produce an atomized powder having a volume-based median particle size d50 of 50 μm or more and 150 μm or less, so that it has a sharp particle size distribution. The median particle size d50 refers to the particle size (median particle size) at which the cumulative particle size distribution (volume basis) from the small particle size side is 50%. d50 can be determined, for example, by measuring in a particle size distribution measuring device "HELOS & RODOS" manufactured by Sympatec under the conditions of dispersion pressure: 4 bar, measurement range: R2, and calculation mode: HRLD.

[0058] In the present embodiment, in the step (S2) of forming atomized powder particles, since the spray temperature is adjusted to a melt in the range of 1100°C to 1400°C (preferably 1250°C to 1350°C), the atomized powder particles 14P are concave. One of the reasons is considered to be the volume shrinkage of the melt droplets generated when rapidly cooled from a high temperature of 1100°C or more (preferably 1250°C or more). In more detail, when the high-temperature droplets fly in the gas and cool, they begin to solidify from the surface of the droplets located in front of the flight direction, generating a shell portion (solid phase). Afterwards, the solidified region (solid phase) begins to grow from the shell portion, and when the temperature of the droplets drops and the volume shrinks, a depression occurs, and solidification ends.

[0059] Figure 5 1 is a diagram showing an example of an electron microscope photograph of particles (atomized powder particles) 14P generated at high temperature according to the present embodiment. Figure 5 This is a reflection electron image obtained by photographing atomized powder particles generated by spraying a molten metal at a temperature of 1300°C using a JCM-6000Plus electron microscope manufactured by JEOL Ltd. Figure 5 As shown, it is preferred to count the number of particles in the field of view of a photograph of atomized powder particles placed on a plane, and more than half of the particles have concave portions. Figure 5 In the example, about 70% of the total number of particles of the atomized powder in the field of view have a concave portion. In this way, most of the particles 14P of the present embodiment are formed with a concave portion 14X. Even if the existing atomization method of ejecting the melt at a temperature below 1250°C and rapidly cooling is used, there is a possibility that some particles will form a concave portion. However, such atomized powder particles with concave portions are currently removed as defective products and are not used. In the present embodiment, such atomized powder particles 14P with concave portions 14X are actively utilized. The presence of the concave portion 14X can reduce the fluidity of the diffusion source powder 14 and increase the ratio of the surface area of ​​each particle 14P to the volume, thereby achieving the effect of improving the adhesion to the adhesive layer described later. The "concave portion" possessed by the atomized powder particles of the present embodiment is an area on the surface of the particle where a depression occurs on the side where the center of gravity of the particle is located, and refers to an area where the maximum diameter of the outer edge of the depressed area is greater than 20% of the diameter of the atomized powder particle. The number of concave portions possessed by the atomized powder particles is not limited to one, and can also be multiple.

[0060] The diffusion source powder 14 of this embodiment has a sharp particle size distribution, and even at any time point in the attachment process, such as Fig. 6A and Figure 6B As shown, particles 14P of the same particle size of the diffusion source powder 14 are attached to the bonding layer 12 of the rare earth system sintered magnet raw material 10. Therefore, it is possible to suppress the particle size of the particles 14P attached to the rare earth system sintered magnet raw material 10 from greatly varying in each manufacturing process, and to make the number of elements diffused from the diffusion source powder 14 to the rare earth system sintered magnet raw material 10 uniform. As a result, it is possible to suppress a large deviation in the magnetic properties of each rare earth system sintered magnet.

[0061] Hereinafter, a configuration example and an operation example of a diffusion source adhering device suitable for adhering the diffusion source powder 14 of the present embodiment to a rare earth system sintered magnet material will be described.

[0062] First, refer to Figure 7 . Figure 7 1 is a diagram schematically showing an example of a general configuration of a diffusion source adhering device 1000 according to the present embodiment. In the diagram, for reference, an X-axis, a Y-axis, and a Z-axis orthogonal to each other are shown.

[0063] exist Figure 7In the example of, the diffusion source attachment device 1000 has a flow trough 100 and a conveying device 200. The flow trough 100 is a device for storing and flowing the diffusion source powder 14 attached to each of a plurality of rare earth system sintered magnet raw materials (workpieces) 10. The diffusion source powder 14 of the present embodiment is an atomized powder manufactured by the aforementioned manufacturing method. Most of the particles 14P contained in the diffusion source powder 14 are formed with a recess 14X. The conveying device 200 has two or more wires 20 that carry and convey a plurality of rare earth system sintered magnet raw materials 10, and can move each wire 20 in a horizontal direction (Y-axis direction). The wire 20 is driven, for example, by a motor. The conveying device 200 conveys a plurality of rare earth system sintered magnet raw materials 10 in a manner such that the plurality of rare earth system sintered magnet raw materials 10 pass through a prescribed space S located above the flow trough 100. The height range of the prescribed space S is within a range of, for example, 5 mm to 100 mm from the upper end of the flow trough 100. In the top view observed from the positive direction of the Z axis, the predetermined space S is contained in the area of ​​the diffusion source powder 14 formed by the flow trough 100 as a fluidized bed. The fluidized bed is formed by supplying an airflow with a certain flow rate or more from below the powder, and the flow resistance to the powder particles is equal to the gravity, so that the powder can flow like a boiling liquid. Such fluidization is also called "fluidization". The presence of a concave portion in the particle 14P does not directly affect the fluidization.

[0064] Next, refer to Figure 8 and Fig. 9 . Figure 8 It is a three-dimensional diagram schematically showing the flow tank 100 and the wire 20 located above it. Fig. 9 This is a perspective view showing a state in which a plurality of rare earth system sintered magnet materials 10 are placed on the wire 20 and the plurality of rare earth system sintered magnet materials 10 are transported in the Y-axis direction by the wire 20 .

[0065] exist Figure 8 In the example shown, the flow cell 100 has the shape of a box with an open top, and has four side portions 100S and a bottom portion 100B. When viewed from the positive direction of the Z axis, the flow cell 100 in the example shown has a rectangular shape in which a pair of sides are parallel to the Y axis direction and the other pair of sides are parallel to the X axis direction. The length of one side is, for example, in the range of 100 mm to 300 mm. In addition, the height of the side portion 100S of the flow cell 100 or the depth of the flow cell 100 is, for example, in the range of 20 mm to 200 mm. However, the shape and size of the flow cell 100 are not limited to the above examples and are arbitrary. When viewed from above, the flow cell 100 may also have a shape other than a rectangle, such as a circular, elliptical, or polygonal shape.

[0066] The side surface 100S of the flow tank 100 can be formed of a metal plate, for example. The outer side surface of the side surface 100S can be inclined, and the cross section can also be a trapezoid. A part or all of the bottom surface 100B of the flow tank 100 has a plurality of holes for air circulation. Such a bottom surface 100B is suitable for being formed of a porous plate, for example.

[0067] The wire 20 may be bent when carrying a plurality of rare earth system sintered magnet raw materials 10, but it is configured so that the wire does not contact the flow groove 100 even in the bent state. The wire 20 is bent due to the weight of the rare earth system sintered magnet raw materials 10, and when the inclination angle of the wire 20 increases, there is a possibility that the rare earth system sintered magnet raw materials 10 slide on the wire 20. In order to prevent such sliding, it is desirable that the inclination angle of the wire 20 is 5 degrees or less. The diameter of the wire 20 can be, for example, in the range of 0.5 mm to 2 mm.

[0068] exist Figure 8 and Fig. 9 In the example of FIG. 1 , the number of the parallel wires 20 is 2. The number of the wires 20 is not limited to 2, and may be 3 or more.

[0069] Next, refer to Fig.10 and Fig.11 . Fig.10 2 is a cross-sectional view schematically showing the flow tank 100 and the wire 20 located thereon. Fig.10 In this state, the diffusion source powder 14 is stored in the flow tank 100, but the flow has not started. Fig.11 This is a cross-sectional view showing a state in which a plurality of rare earth system sintered magnet raw materials 10 are conveyed in the Y-axis direction by the wire rod 20 while the diffusion source powder in the flow channel 100 begins to flow.

[0070] In the example shown in the figure, the flow trough 100 has a porous area 120 on the bottom surface. The diffusion source attachment device 1000 of this embodiment has an air flow device 140 that flows gas from the porous area 120 and blows up the diffusion source powder 14 in the flow trough 100. The air flow sent from the air flow device 140 to the flow trough 100 through the porous area 120 fluidizes the diffusion source powder 14 in the flow trough 100 to form a fluidized layer. In the embodiment of the present invention, the diffusion source powder 14 is attached to the surface of the rare earth sintered magnet raw material 10 outside (above) the flow trough 100 instead of inside the diffusion source powder 14 where the fluidized layer is formed inside the flow trough 100. This is because in the embodiment of the present invention, as long as the attachment of about one layer of powder particles can be achieved uniformly, it is not necessary to attach a thick particle layer. Therefore, when forming a fluidized layer, the diffusion source powder 14 is preferably blown up to a height of about 10 mm to 30 mm from the upper surface of the flow trough 100.

[0071] In this embodiment, when the plurality of rare earth system sintered magnet raw materials 10 conveyed by the wire 20 of the conveying device 200 respectively pass through the prescribed space S located above the flow trough 100, the plurality of rare earth system sintered magnet raw materials 10 are in a state where the adhesive layer 12 is provided on the surface of each of the plurality of rare earth system sintered magnet raw materials 10. Such an adhesive layer 12 can be formed by applying an adhesive liquid to the rare earth system sintered magnet raw materials 10 on the wire 20 using a spray device or the like. Using the flow trough 100, the particles 14P of the diffusion source powder 14 suspended in the prescribed space S adhere to the adhesive layer 12 of the rare earth system sintered magnet raw material 10 moving in the horizontal direction. At this time, the particles 14P form a particle layer by directly contacting and adhering to the adhesive layer 12. Among them, the particles 14P may form other particle layers on such a particle layer. However, such particles 14P constituting other particle layers do not directly contact the adhesive layer 12, and thus do not adhere. Therefore, by the air blowing process performed later, other particle layers can be easily removed, and a state in which substantially one layer of particle layer covers the surface of the adhesive layer 12 is formed. In this way, the adhesion of the diffusion source powder is controlled. As a result, it is possible to perform uniform diffusion with good reproducibility, and suppress the deviation of the magnetic properties.

[0072] In order to carry out the above-mentioned blowing process, the diffusion source attachment device 1000, or the manufacturing equipment including the diffusion source attachment device 1000 may also have a device (not shown) for removing unnecessary particles from the diffusion source powder 14 passing through the specified space S and attached to the adhesive layer 12 by using air blowing.

[0073] Refer again Figure 7 .

[0074] In the present embodiment, the diffusion source attachment device 1000 further includes a flow trough storage chamber 300 and a circulation mechanism 400 surrounding the flow trough 100. The flow trough storage chamber 300 includes a recovery unit 30 for recovering the diffusion source powder 14 overflowing from the flow trough 100. The flow trough storage chamber 300 preferably has a funnel-shaped inclination at the lower portion, and the recovery unit 30 is provided at the lower end thereof. The particles of the diffusion source powder 14 suspended in the flow trough storage chamber 300 fall due to their own weight and are collected in the recovery unit 30. The circulation mechanism 400 is configured to deliver the diffusion source powder 14 recovered by the recovery unit 30 to the flow trough 100.

[0075] In this embodiment, the circulation mechanism 400 has a pipe 40 for conveying the diffusion source powder 14 from the recovery unit 30 to the flow tank 100 by air flow. Specifically, by the operation of the ejector E1, the air flowing in the pipe 40 conveys the diffusion source powder 14 in the recovery unit 30 by air flow. The ejector E1 is supplied with a gas such as air pressurized by a pump (not shown) via a valve V1.

[0076] The pipeline 40 is connected to the flow tank storage chamber 300. In the flow tank storage chamber 300, the front end of the pipeline 40 is configured to be able to supply the diffusion source powder 14 to the flow tank 100. A funnel-shaped relay container may also be provided between the front end of the pipeline 40 and the flow tank 100. Such a relay container has a small opening at the bottom, and can function as a buffer device for adjusting the supply rate, so that the diffusion source powder 14 transported through the pipeline 40 will not be supplied to the flow tank 100 in large quantities at once. The relay device has the function of separating the diffusion source powder 14 from the transport air and preventing the recovered diffusion source powder 14 from falling directly on the workpiece 10. By providing such a relay device, the diffusion source powder 14 from the flow tank 100 can be stably attached to the workpiece 10 without changes due to the recovered diffusion source powder 14.

[0077] The diffusion source attachment device 1000 of the present embodiment includes a diffusion source powder supply device 500 for resupplying the diffusion source powder 14 from the outside of the flow trough storage chamber 300 to the inside of the flow trough storage chamber 300. As described above, the particles 14P of the diffusion source powder 14 blown up from the flow trough 100 are attached to the adhesive layer 12 of the rare earth system sintered magnet raw material 10 passing over the flow trough 100, and the amount of the diffusion source powder 14 existing in the flow trough storage chamber 300 gradually decreases. The particles 14P of the diffusion source powder 14 overflowing from the flow trough 100 are recovered and returned to the flow trough 100 by the operation of the circulation mechanism 400. When the amount of the diffusion source powder 14 existing in the flow trough storage chamber 300 decreases, the particles 14P of the diffusion source powder 14 recovered will naturally decrease, and the diffusion source powder 14 stored in the flow trough 100 will become insufficient. The diffusion source powder supply device 500 supplies new diffusion source powder 14 to the interior of the flow tank storage chamber 300 so that the diffusion source powder 14 stored in the flow tank 100 will not be insufficient. This supply is implemented by using the injector E2 to eject the diffusion source powder stored in the diffusion source powder supply device 500 through the pipeline into the interior of the flow tank storage chamber 300. The injector E2 is supplied with pressurized gas such as air through the valve V2.

[0078] The diffusion source attachment device 1000 of this embodiment has a control device 600 for controlling the diffusion source powder supply device 500 and a sensor 52 for detecting the amount or height of the diffusion source powder 14 recovered by the recovery unit 30. The control device 600 is composed of a computer and has a processor and a storage device. The processor is one or more semiconductor integrated circuits, also known as a central processing unit (CPU) or a microprocessor. The processor executes the computer program stored in the storage device in sequence to achieve the desired processing. Such processing can also be performed by a programmable logic controller (PLC).

[0079] When the control device 600 determines that the amount or height of the diffusion source powder 14 in the recovery unit 30 decreases and reaches a first value, the control device 600 starts to supply new diffusion source powder 14 from the diffusion source powder supply device 500 to the flow tank 100. Furthermore, when the amount or height of the diffusion source powder 14 in the recovery unit 30 increases and reaches a second value greater than the first value, the control device 600 stops supplying the diffusion source powder 14 from the diffusion source powder supply device 500 to the flow tank storage chamber 300. In this way, the new diffusion source powder 14 supplied from the diffusion source powder supply device 500 to the flow tank storage chamber 300 is recovered by the recovery unit 30 and supplied to the flow tank 100 through the operation of the circulation mechanism 400.

[0080] The sensor 52 may include two height detectors arranged at different heights. Such a height detector may, for example, have a structure that sandwiches the space in the recovery unit 30 and is configured with a light emitting unit and a light receiving unit. By using such a height detector, the light receiving unit detects that the diffusion source powder 14 in the recovery unit 30 blocks the light emitted from the light emitting unit, thereby determining that the height of the diffusion source powder 14 in the recovery unit 30 has reached a predetermined height. Among them, examples of the sensor 52 include a photoelectric sensor, an ultrasonic sensor, a laser sensor, and a pulse vibration level sensor. Among these, from the perspective of accurately detecting the height of the powder particles of the diffusion source powder 14, a pulse vibration level sensor is preferred. By using this embodiment, the particles 14P of the diffusion source powder 14 can be stably attached to the bonding layer 12 of the rare earth sintered magnet raw material 10. The time point and supply amount of the new diffusion source powder 14 supplied to the flow tank storage chamber 300 can be monitored based on the amount of the diffusion source powder 14 in the recovery unit 30, so it is possible to maintain the amount of the necessary diffusion source powder without setting other expensive sensors.

[0081] Hereinafter, an embodiment of the method for manufacturing a rare earth sintered magnet of the present invention will be described. The above-mentioned diffusion source attachment device 1000 can attach various diffusion source powders to the raw material of the rare earth sintered magnet, and the composition of the diffusion source powder is not limited. Herein, an embodiment of the method for manufacturing an RTB sintered magnet including a step of attaching a diffusion source powder containing a heavy rare earth element using the above-mentioned diffusion source attachment device will be described.

[0082] <Method for producing rare earth sintered magnet>

[0083] like Fig.12As shown, the method for manufacturing a rare earth sintered magnet of the present embodiment may include: a step S10 of preparing a raw material for an R1-TB sintered magnet; a step S20 of preparing a diffusion source powder such as an RMA alloy; a step S30 of applying an adhesive layer to the surface of the R1-TB sintered magnet raw material; a step S40 of attaching a diffusion source powder to the surface of the R1-TB sintered magnet raw material; and a diffusion step S50. The diffusion step S50 is a heat treatment step of heating the magnet raw material with the diffusion source powder of the rare earth alloy attached to the surface at a temperature of 700°C to 1100°C in a vacuum or inert gas atmosphere to diffuse the elements contained in the diffusion source powder into the interior of the R1-TB sintered magnet raw material.

[0084] In the present invention, the R1-TB sintered magnet before and during the diffusion process is sometimes referred to as a "rare earth sintered magnet raw material", and the rare earth sintered magnet after the diffusion process is simply referred to as a "rare earth sintered magnet". These processes are described in more detail below.

[0085] In the present embodiment, in the step S20 of preparing the diffusion source powder, the diffusion source powder containing a plurality of atomized powder particles formed of a rare earth alloy is prepared by the aforementioned atomization method. Specifically, it includes the step of preparing a molten rare earth alloy and the step of forming a plurality of atomized powder particles from the molten metal heated to a temperature of 1100°C to 1400°C (preferably 1250°C to 1350°C) by the atomization method. In addition, the rare earth alloy is an RMA alloy. Among them, R contains at least one rare earth element and contains at least one of Nd and Pr. M is at least one selected from Cu, Ga, Co and Fe. A is at least one selected from Al, Si, Ti, V, Cr, Mn, Co, Ni, Zn, Ge, Zr, Nb, Mo, Ag and B.

[0086] (Process of Preparing Raw Materials for Rare Earth Sintered Magnets)

[0087] The rare earth (R1-TB) sintered magnet raw material of this embodiment has the following composition, for example.

[0088] R1: 26.6 mass% or more and 31.5 mass% or less (R1 is a rare earth element);

[0089] B: 0.8 mass% to 1.0 mass%, preferably 0.88 mass% to 0.97 mass%;

[0090] M: 0 mass% to 1.0 mass% (M is at least one selected from Ga, Cu, Zn and Si), M1: 0 mass% to 2.0 mass% (M1 is at least one selected from Al, Ti, V, Cr, Mn, Ni, Zr, Nb, Mo, Ag, In, Sn, Hf, Ta, W, Pb and Bi);

[0091] The remainder is T (T is Fe or Fe and Co) and inevitable impurities.

[0092] Next, a method for producing the rare earth system sintered magnet material having the above composition will be described.

[0093] First, after preparing an alloy for a rare earth system sintered magnet, the alloy is coarsely pulverized by, for example, a hydrogen pulverization method.

[0094] The following is an example of a method for producing an alloy for a rare earth sintered magnet. The alloy ingot can be obtained by an ingot casting method in which a metal or alloy pre-adjusted to the above composition is melted and added to a mold to solidify it. The alloy can also be produced by a strip casting method in which a molten metal or alloy pre-adjusted to the above composition is brought into contact with a single roll, double rolls, a rotating disk or a rotating cylindrical mold to rapidly cool and produce a rapidly solidified alloy. Other rapid cooling methods such as centrifugal casting can also be used to produce thin-sheet alloys.

[0095] In an embodiment of the present invention, an alloy manufactured by any method of an ingot casting method and a quenching method can be used, and an alloy manufactured by a quenching method such as a strip casting method is preferably used. The thickness of the alloy made by the quenching method is usually in the range of 0.03 mm to 1 mm, and is in the shape of a thin sheet. By hydrogen pulverizing the obtained alloy, the size of the hydrogen pulverized powder (coarse pulverized powder) can be made, for example, less than 1.0 mm. The coarse pulverized powder thus obtained is pulverized by a jet mill.

[0096] The jet mill pulverization is performed in an inert atmosphere such as nitrogen. The pulverization can be performed, for example, by a jet mill in a humidified atmosphere.

[0097] Fine powders used to make raw materials for rare earth sintered magnets may be made from one raw material alloy (single raw material alloy) or by mixing two or more raw material alloys (blending method) as long as they satisfy the above conditions.

[0098] In a preferred embodiment, after a powder molded body is made from the above-mentioned fine powder by pressing in a magnetic field, the powder molded body is sintered. When pressing in a magnetic field, from the viewpoint of suppressing oxidation, it is preferred to form a powder molded body by pressing in an inert gas atmosphere or wet pressing. In particular, with regard to wet pressing, the surface of the particles constituting the powder molded body is covered with a dispersant such as an oil agent, which can suppress contact with oxygen or water vapor in the atmosphere. Therefore, it is possible to prevent or suppress oxidation of the particles by the atmosphere before, during or after the pressing process. Therefore, it is easy to control the oxygen content within a specified range. In the case of wet pressing in a magnetic field, a slurry in which a dispersion medium is mixed in the fine powder is prepared, supplied to the mold cavity of the mold of the wet pressing device, and compression molding is performed in a magnetic field.

[0099] Next, the molded body is sintered to obtain a rare earth sintered magnet raw material. The molded body is preferably sintered at 0.13 Pa (10 -3 Torr) or less, more preferably 0.07 Pa (5.0×10 -4 Torr) and at a temperature range of 1000°C to 1150°C. In order to prevent oxidation caused by sintering, the residual gas in the atmosphere can be replaced with an inactive gas such as helium or argon. The obtained sintered body (rare earth sintered magnet raw material) can also be heat treated. The heat treatment conditions such as heat treatment temperature and heat treatment time can adopt known conditions.

[0100] (Step of Preparing Diffusion Source Powder)

[0101] In this embodiment, as the diffusion source powder, an atomized powder of the RMA alloy produced by the above-mentioned method is used. R contains at least one rare earth element and contains at least one of Nd and Pr. M is at least one selected from Cu, Ga, Co and Fe. A is at least one selected from Al, Si, Ti, V, Cr, Mn, Co, Ni, Zn, Ge, Zr, Nb, Mo, Ag and B. More preferably, A is at least one selected from Al, Si, Ti, V, Cr, Mn, Co, Ni, Zn, Ge, Zr, Nb, Mo and Ag.

[0102] In one embodiment, the composition ratio of R is 65 mass % to 95 mass % of the whole RMA alloy, the composition ratio of M is 5 mass % to 35 mass % of the whole RMA alloy, and the composition ratio of A is 0 mass % to 3 mass % of the whole RMA alloy. cJ Preferably, R is 85 mass % to 95 mass % of the entire RMA alloy, and M is 5 mass % to 15 mass % of the entire RMA alloy.

[0103] Preferably, the total composition ratio of Nd and Pr is 60 mass % or more of the entire R. M includes at least one of Cu and Ga, and the total composition ratio of Cu and Ga is 50 mass % or more of the entire M.

[0104] The content of Tb and Dy in R is preferably 3% by mass or more and 24% by mass or less of the total RMA alloy. In addition, the content of Pr in R is preferably 65% ​​by mass or more and 86% by mass or less of the total RMA alloy. In addition, M preferably must contain at least one of Ga and Cu. A higher H cJ The content of Pr in the RMA alloy is preferably 50 mass % or more of the total R, and more preferably R contains only Pr and Tb. By containing Pr, diffusion in the grain boundary phase becomes easier, so Tb can be diffused more efficiently, and a higher H can be obtained. cJ .

[0105] Next, a method for producing a diffusion source powder containing an RMA alloy will be described.

[0106] The diffusion source powder containing the RMA alloy can be prepared from a melt having a higher temperature than the above-mentioned conventional example by using an atomization method. The diffusion source powder is not limited to the powder of the RMA alloy, and can also replace the powder of the RMA alloy, or in addition to the powder of the RMA alloy, include powders of other types of alloys or compounds.

[0107] (Adhesive coating process)

[0108] In the present embodiment, the adhesive coating step (adhesive layer forming step) is performed before the diffusion source powder attaching step.

[0109] As the adhesive applied to the surface of the raw material of the rare earth sintered magnet, PVA (polyvinyl alcohol), PVB (polyvinyl butyral), PVP (polyvinyl pyrrolidone) and the like can be cited. In the case where the adhesive layer is a water-based adhesive, the raw material of the rare earth sintered magnet can be preheated before coating. The purpose of preheating is to remove excess solvent to control the adhesive force and to make the adhesive layer adhere evenly. The heating temperature is preferably 60 to 100°C. In the case of an adhesive layer of a highly volatile organic solvent system, this step can be omitted.

[0110] The method of applying the adhesive on the surface of the raw material of the rare earth sintered magnet can be any method. As specific examples of coating, spraying, dipping, coating using a dispensing machine, etc. can be cited. In a preferred embodiment, the adhesive is applied to the entire surface (the entire surface) of the raw material of the rare earth sintered magnet. It is also possible to apply the adhesive not to the entire surface of the raw material of the rare earth sintered magnet, but partially. In particular, when the thickness of the raw material of the rare earth sintered magnet is relatively thin (for example, about 2 mm), sometimes only the diffusion source powder is attached to the surface with the largest area on the surface of the raw material of the rare earth sintered magnet, so that the necessary elements can be diffused to the entire magnet. Utilizing the manufacturing method of the present invention, for multiple surfaces with different normal directions on the surface of the raw material of the rare earth sintered magnet, the diffusion source powder can be attached through a single process. The thickness of the adhesive layer is preferably greater than 10 μm and less than 100 μm.

[0111] (Diffusion source powder attachment process)

[0112] In this embodiment, using Figure 7 The diffusion source adhering apparatus 1000 shown is used to adhere diffusion source powder of RMA alloy to the surface of a rare earth system sintered magnet material.

[0113] At this time, if Fig.11 As shown, the adhesion of the diffusion source powder ends while the rare earth sintered magnet raw material is being conveyed by the wire 20. The conveying speed of the wire 20 in this embodiment is in the range of 500 mm / min to 2000 mm / min, and the time required for the diffusion source powder to adhere to one rare earth sintered magnet raw material is only about 1 to 2 seconds. In addition, the diffusion source powder adheres to the rare earth sintered magnet raw material while it is supported by the fine wire, so the diffusion source powder can be uniformly adhered to almost all surfaces of the rare earth sintered magnet raw material. Using this embodiment, atomized powder particles made from a high-temperature melt of the diffusion source powder are Figure 4 As shown, it has a sharp particle size distribution. Therefore, the particle size of the atomized powder particles attached to the raw material of the rare earth sintered magnet is uniform. In addition, the atomized powder particles are formed with recesses, so the ratio of the surface area to the particle size increases. As a result, the contact area between the adhesive layer and the atomized powder particles increases, and the bonding force is improved. As a result, it is possible to suppress the atomized powder particles from peeling off from the adhesive layer.

[0114] In this embodiment, the bottom area of ​​the recovery unit 30 is 2700 mm 2The control device 600 is set to supply the diffusion source powder 14 from the diffusion source powder supply device 500 to the flow tank storage chamber 300 when the height of the diffusion source powder 14 in the recovery unit 30 decreases and reaches the first value (85 mm), and to stop supplying when the height of the diffusion source powder 14 increases and reaches the second value (140 mm). In this way, the amount of the diffusion source powder 14 in the flow tank 100 can be maintained within an appropriate range. As a result, the deviation of the amount of the diffusion source attachment process can be suppressed, and highly uniform attachment can be achieved.

[0115] (Diffusion process)

[0116] The following diffusion process is performed: the raw material of the rare earth sintered magnet having the diffusion source powder of the RMA alloy attached to the surface is heated in a vacuum or inert gas atmosphere at a temperature of 700°C to 1100°C to diffuse R and M into the interior of the raw material of the rare earth sintered magnet. Thus, a liquid phase containing R and M is generated from the RMA alloy, and the liquid phase is diffused from the surface of the sintered body into the interior through the grain boundaries in the raw material of the rare earth sintered magnet. At this time, it is preferred to increase the content of the heavy rare earth element RH (preferably Tb) contained in the raw material of the rare earth sintered magnet to an extremely small amount in the range of 0.05 mass% to 0.30 mass%. Thus, the consumption of the heavy rare earth element RH can be suppressed, and an extremely high RH can be obtained. cJ Improved effect. In order to increase the content of RH contained in the raw material of rare earth sintered magnet by 0.05 mass% or more and 0.30 mass% or less, various conditions such as the amount of RMA alloy, the heating temperature during treatment, the particle size (when the RMA alloy is in granular form), and the treatment time can be adjusted. Among these, by adjusting the amount of RMA alloy and the heating temperature during treatment, the amount (increase) of heavy rare earth element RH introduced can be controlled relatively easily. Utilizing this embodiment, the particle size of the atomized powder particles attached to the raw material of rare earth sintered magnet is uniformized, so the amount (increase) of heavy rare earth element RH introduced can be controlled with high precision, reducing the deviation of magnet properties.

[0117] In this specification, for example, "increasing the Tb content by 0.05 mass% or more and 0.30 mass% or less" means that, in the content expressed in mass%, the numerical value increases by 0.05 or more and 0.30 or less. For example, when the Tb content of the rare earth sintered magnet raw material before the diffusion process is 0.50 mass% and the Tb content of the RTB system sintered magnet after the diffusion process is 0.60 mass%, the Tb content is increased by 0.10 mass% by the diffusion process. Whether the content (RH amount) of at least one of Tb and Dy is increased by 0.05 mass% or more and 0.30 mass% or less can be calculated by measuring the rare earth sintered magnet raw material before the diffusion process and the RTB system sintered magnet after the diffusion process (the whole RH amount) respectively, and finding how much the RH amount increases before and after the diffusion. In addition, when there is a RMA alloy enriched portion on the surface of the RTB system sintered magnet after the diffusion, it is preferable to remove the enriched portion by cutting or the like and then measure the RH amount.

[0118] When the heating temperature is lower than 700°C, for example, the amount of liquid phase containing Tb, Pr and M is too small to obtain a high H cJ On the other hand, above 1100°C, there is H cJ The temperature is preferably 850°C or higher and 980°C or lower. cJ .

[0119] In addition, powders of fluoride, oxide, oxyfluoride, etc. of heavy rare earth element RH may be attached to the surface of RTB-based sintered magnet raw material together with the diffusion source powder of RMA alloy. Thus, light rare earth elements RL and M can be diffused into the interior of RTB-based sintered magnet raw material together with heavy rare earth element RH. Examples of fluoride, oxide, and oxyfluoride of heavy rare earth element RH include TbF3, DyF3, Tb2O3, Dy2O3, Tb4OF, and Dy4OF.

[0120] (Heat treatment process)

[0121] The RTB based sintered magnet after the diffusion treatment step can be heat treated in a vacuum or inert gas atmosphere at a temperature of 450°C to 750°C and lower than the temperature applied during the diffusion treatment. cJ .

[0122] The present invention includes the inventions described in the following items.

[0123] [Project 1]

[0124] A method for manufacturing a diffusion source powder, wherein the diffusion source powder contains a plurality of atomized powder particles formed of a rare earth alloy, the manufacturing method comprising:

[0125] A step of preparing a melt of the rare earth alloy; and

[0126] The step of forming a plurality of atomized powder particles from the molten liquid heated to a temperature of 1100° C. to 1400° C. by atomization,

[0127] The above rare earth alloy is RMA alloy.

[0128] R contains at least one rare earth element and contains at least one of Nd and Pr,

[0129] M is at least one selected from Cu, Ga, Co and Fe,

[0130] A is at least one selected from Al, Si, Ti, V, Cr, Mn, Co, Ni, Zn, Ge, Zr, Nb, Mo, Ag and B.

[0131] [Project 2]

[0132] A method for manufacturing a diffusion source powder as described in Item 1, wherein the composition ratio of R is greater than 65 mass % and less than 95 mass % of the entire RMA alloy, the composition ratio of M is greater than 5 mass % and less than 35 mass % of the entire RMA alloy, and the composition ratio of A is greater than 0 mass % and less than 3 mass % of the entire RMA alloy.

[0133] [Item 3]

[0134] A method for producing a diffusion source powder as described in item 2, wherein A is at least one selected from Al, Si, Ti, V, Cr, Mn, Co, Ni, Zn, Ge, Zr, Nb, Mo and Ag.

[0135] [Item 4]

[0136] The method for producing a diffusion source powder according to item 2 or 3, wherein the total composition ratio of Nd and Pr is 60 mass % or more of the entire R,

[0137] M contains at least one of Cu and Ga, and the total composition ratio of Cu and Ga is 50 mass % or more of the entire M.

[0138] [Item 5]

[0139] The method for producing a diffusion source powder according to any one of items 1 to 4, wherein:

[0140] The step of forming the atomized powder particles includes the step of spraying the molten metal, wherein the temperature of the molten metal is adjusted to be in the range of 1250° C. to 1350° C.

[0141] [Item 6]

[0142] The method for producing a diffusion source powder according to any one of items 1 to 5, wherein the step of forming the atomized powder particles includes the step of forming a recessed portion on each of more than half of the atomized powder particles.

[0143] [Item 7]

[0144] A diffusion source powder comprising a plurality of atomized powder particles formed of a rare earth alloy,

[0145] The above rare earth alloy is RMA alloy.

[0146] R contains at least one rare earth element and contains at least one of Nd and Pr,

[0147] M is at least one selected from Cu, Ga, Co and Fe,

[0148] A is at least one selected from Al, Si, Ti, V, Cr, Mn, Co, Ni, Zn, Ge, Zr, Nb, Mo, Ag and B,

[0149] More than half of the plurality of atomized powder particles each have a concave portion.

[0150] [Item 8]

[0151] The diffusion source powder as described in Item 7, wherein the composition ratio of R is greater than 65 mass % and less than 95 mass % of the entire RMA alloy, the composition ratio of M is greater than 5 mass % and less than 35 mass % of the entire RMA alloy, and the composition ratio of A is greater than 0 mass % and less than 3 mass % of the entire RMA alloy.

[0152] [Item 9]

[0153] The diffusion source powder as described in item 7 or 8, wherein A is at least one selected from Al, Si, Ti, V, Cr, Mn, Co, Ni, Zn, Ge, Zr, Nb, Mo and Ag.

[0154] [Item 10]

[0155] The diffusion source powder according to any one of items 7 to 9, wherein the total composition ratio of Nd and Pr is 60 mass % or more of the entire R,

[0156] M contains at least one of Cu and Ga, and the total composition ratio of Cu and Ga is 50 mass % or more of the entire M.

[0157] [Item 11]

[0158] The diffusion source powder according to any one of items 7 to 10, wherein a volume-based median diameter d50 is 50 μm or more and 150 μm or less.

[0159] [Item 12]

[0160] A method for producing a rare earth sintered magnet, comprising:

[0161] A step of preparing the diffusion source powder according to any one of items 7 to 11;

[0162] A step of preparing a rare earth system sintered magnet raw material having an adhesive layer provided on at least a portion of the surface;

[0163] a step of attaching the diffusion source powder to the bonding layer of the rare earth system sintered magnet raw material; and

[0164] The step of heating the rare earth system sintered magnet material to diffuse the elements contained in the diffusion source powder from the diffusion source powder attached to the bonding layer into the interior of the rare earth system sintered magnet material.

[0165] [Item 13]

[0166] In the method for producing a rare earth system sintered magnet according to item 12, the step of causing the diffusion source powder to adhere to the bonding layer comprises:

[0167] The step of placing the diffusion source powder into a flow tank;

[0168] a step of causing the diffusion source powder to flow; and

[0169] A step of bringing the flowing diffusion source powder into contact with the bonding layer of the moving rare earth system sintered magnet raw material carried on a wire rod.

[0170] [Item 14]

[0171] A method for producing a rare earth sintered magnet, comprising:

[0172] A step of preparing a diffusion source powder by using the manufacturing method described in any one of items 1 to 6;

[0173] A step of preparing a rare earth system sintered magnet raw material having an adhesive layer provided on at least a portion of the surface;

[0174] a step of attaching the diffusion source powder to the bonding layer of the rare earth system sintered magnet raw material; and

[0175] The step of heating the rare earth system sintered magnet material to diffuse the elements contained in the diffusion source powder from the diffusion source powder attached to the bonding layer into the interior of the rare earth system sintered magnet material.

[0176] [Item 15]

[0177] In the method for producing a rare earth system sintered magnet according to item 14, the step of causing the diffusion source powder to adhere to the bonding layer comprises:

[0178] The step of placing the diffusion source powder into a flow tank;

[0179] a step of causing the diffusion source powder to flow; and

[0180] A step of bringing the flowing diffusion source powder into contact with the bonding layer of the moving rare earth system sintered magnet raw material carried on a wire rod.

[0181] Industrial Applicability

[0182] The embodiment of the present invention can use less heavy rare earth element RH to improve the H of RTB based sintered magnet. cJ , and thus can be used for the production of rare earth sintered magnets requiring high coercivity. In addition, the present invention can also be widely used in technologies that require the diffusion of other metal elements other than the heavy rare earth element RH from the surface into the rare earth sintered magnet.

Claims

1. A method for producing a diffusion source powder, the diffusion source powder comprising a plurality of atomized powder particles formed of a rare earth alloy, the method comprising: A step of preparing a melt of the rare earth alloy; and The step of forming a plurality of atomized powder particles from the molten liquid heated to a temperature of 1100° C. to 1400° C. by an atomization method, The rare earth alloy is an RMA alloy, R contains at least one rare earth element and contains at least one of Nd and Pr, M is at least one selected from Cu, Ga, Co and Fe, A is at least one selected from Al, Si, Ti, V, Cr, Mn, Co, Ni, Zn, Ge, Zr, Nb, Mo, Ag and B.

2. The method for producing a diffusion source powder according to claim 1, wherein: The composition ratio of R is 65 mass % or more and 95 mass % or less of the entire RMA alloy. The composition ratio of M is 5 mass % or more and 35 mass % or less of the entire RMA alloy. The composition ratio of A is not less than 0 mass % and not more than 3 mass % of the entire RMA alloy.

3. The method for producing a diffusion source powder according to claim 2, wherein: The total composition ratio of Nd and Pr is 60 mass % or more of the entire R. M contains at least one of Cu and Ga, and the total composition ratio of Cu and Ga is 50 mass % or more of the entire M.

4. The method for producing a diffusion source powder according to claim 3, wherein: The step of forming the atomized powder particles includes a step of spraying the molten metal, wherein the temperature of the molten metal is adjusted to be in a range of 1250° C. to 1350° C.

5. The method for producing a diffusion source powder according to any one of claims 1 to 4, characterized in that: The step of forming the atomized powder particles includes forming a concave portion on each of more than half of the atomized powder particles.

6. A diffusion source powder, characterized in that: Containing a plurality of atomized powder particles formed of a rare earth alloy, The rare earth alloy is an RMA alloy, R contains at least one rare earth element and contains at least one of Nd and Pr, M is at least one selected from Cu, Ga, Co and Fe, A is at least one selected from Al, Si, Ti, V, Cr, Mn, Co, Ni, Zn, Ge, Zr, Nb, Mo, Ag and B, More than half of the plurality of atomized powder particles each have a concave portion.

7. The diffusion source powder according to claim 6, characterized in that: The composition ratio of R is 65 mass % or more and 95 mass % or less of the entire RMA alloy. The composition ratio of M is 5 mass % or more and 35 mass % or less of the entire RMA alloy. The composition ratio of A is not less than 0 mass % and not more than 3 mass % of the entire RMA alloy.

8. The diffusion source powder according to claim 7, characterized in that: The total composition ratio of Nd and Pr is 60 mass % or more of the entire R. M contains at least one of Cu and Ga, and the total composition ratio of Cu and Ga is 50 mass % or more of the entire M.

9. The diffusion source powder according to claim 8, characterized in that: The volume-based median particle size d50 is 50 μm or more and 150 μm or less.

10. A method for producing a rare earth sintered magnet, characterized in that: include: A step of preparing the diffusion source powder according to any one of claims 6 to 9; A step of preparing a rare earth system sintered magnet raw material having an adhesive layer provided on at least a portion of the surface; a step of making the diffusion source powder adhere to the bonding layer of the rare earth system sintered magnet raw material; and The step of heating the rare earth system sintered magnet material to diffuse the elements contained in the diffusion source powder from the diffusion source powder attached to the bonding layer into the interior of the rare earth system sintered magnet material.

11. The method for producing a rare earth sintered magnet according to claim 10, wherein: The step of attaching the diffusion source powder to the adhesive layer includes: The step of placing the diffusion source powder into a flow tank; a step of causing the diffusion source powder to flow; and A step of bringing the flowing diffusion source powder into contact with the bonding layer of the moving rare earth system sintered magnet raw material carried on a wire rod.

12. A method for producing a rare earth sintered magnet, characterized in that: include: A step of preparing diffusion source powder using the manufacturing method according to any one of claims 1 to 5; A step of preparing a rare earth system sintered magnet raw material having an adhesive layer provided on at least a portion of the surface; a step of making the diffusion source powder adhere to the bonding layer of the rare earth system sintered magnet raw material; and The step of heating the rare earth system sintered magnet material to diffuse the elements contained in the diffusion source powder from the diffusion source powder attached to the bonding layer into the interior of the rare earth system sintered magnet material.

13. The method for producing a rare earth sintered magnet according to claim 12, wherein: The step of attaching the diffusion source powder to the adhesive layer includes: The step of placing the diffusion source powder into a flow tank; a step of causing the diffusion source powder to flow; and A step of bringing the flowing diffusion source powder into contact with the bonding layer of the moving rare earth system sintered magnet raw material carried on a wire rod.

Images