CN117577438A

CN117577438A - Diffusion source attaching device and method for manufacturing rare earth sintered magnet

Info

Publication number: CN117577438A
Application number: CN202310229538.9A
Authority: CN
Inventors: 西村征吾; 久保贤一; 水野晶仁
Original assignee: Bomeilicheng Co ltd
Current assignee: Bomeilicheng Co ltd
Priority date: 2022-03-24
Filing date: 2023-03-10
Publication date: 2024-02-20
Also published as: JP2023141387A

Abstract

The invention aims to solve the technical problem of uniformly coating diffusion source powder on the surface of a rare earth sintered magnet with high efficiency. The present invention provides a diffusion source attaching device, comprising: a flow tank for storing and flowing diffusion source powders attached to each of the rare earth sintered magnet raw materials; and a conveying device having 2 or more wires on which the plurality of rare earth sintered magnet raw materials are placed and conveyed, wherein the plurality of rare earth sintered magnet raw materials are conveyed in such a manner that the plurality of rare earth sintered magnet raw materials pass through a predetermined space located above the flow groove by moving the wires in a horizontal direction.

Description

Diffusion source attaching device and method for manufacturing rare earth sintered magnet

Technical Field

The present invention relates to a diffusion source attaching device and a method for manufacturing a rare earth sintered magnet using the same.

Background

By R ₂ T ₁₄ The B-type compound (R is rare earth element,R-T-B sintered magnets having T as the main phase Fe or Fe and Co) are known as the most excellent permanent magnets, and are used for various motors such as Voice Coil Motors (VCM) of hard disk drives and motors for mounting hybrid vehicles, home electric appliances, and the like.

R-T-B sintered magnet has intrinsic coercivity H at high temperature _cJ (hereinafter abbreviated as "H _cJ ") is reduced, thus causing irreversible thermal demagnetization. In order to avoid irreversible thermal demagnetization, it is required to maintain high H even at high temperature when used in motor applications and the like _cJ 。

In R-T-B sintered magnets, R is replaced with a heavy rare earth element RH (Dy, tb) ₂ T ₁₄ In the case of part R in the B-type compound phase, H _cJ Improving the quality. To obtain high H at high temperature _cJ It is effective to add a large amount of heavy rare earth element RH to the R-T-B sintered magnet. However, in the R-T-B sintered magnet, when the heavy rare earth element RH is used as R to replace the light rare earth element RL (Nd, pr), H is used as the R _cJ An increased residual magnetic flux density B _r (hereinafter abbreviated as "B _r ") decrease. In addition, the heavy rare earth element RH is a rare resource, and thus it is required to reduce the amount used thereof.

In recent years, therefore, improvement of H of R-T-B sintered magnets by using less heavy rare earth element RH has been studied _cJ And not decrease B _r Is a technology of (a). For example, it is proposed to cause a fluoride or oxide of a heavy rare earth element RH, or various metals M or M alloys, to be present on the surface of a sintered magnet, individually or in combination, and to perform a heat treatment in this state, thereby diffusing the heavy rare earth element RH contributing to the improvement of coercive force into the magnet.

Patent document 1 discloses a technique using R oxide, R fluoride, and R oxyfluoride powder (R is a rare earth element).

Patent document 2 discloses a technique of using a powder of RM (M is 1 or more selected from Al, cu, zn, ga and the like) alloy.

Patent documents 3 and 4 disclose that, by using a mixed powder of an RM alloy (M is 1 or more selected from Al, cu, zn, ga and the like), an M1M2 alloy (M1M 2 is 1 or more selected from Al, cu, zn, ga and the like), and an RH oxide, the RH oxide can be partially reduced by the RM alloy and the like at the time of heat treatment, and a heavy rare earth element RH can be introduced into the magnet.

Prior art literature

Patent literature

Patent document 1: international publication No. 2006/043348

Patent document 2: japanese patent laid-open No. 2008-263179

Patent document 3: japanese patent application laid-open No. 2012-248827

Patent document 4: japanese patent application laid-open No. 2012-248828

Patent document 5: international publication No. 2015/163397

Patent documents 1 to 4 disclose methods of heat-treating a mixed powder containing an RH compound powder over the entire surface of a magnet (the entire surface of the magnet). According to specific examples of these methods, the mixed powder is dispersed in water or an organic solvent to prepare a slurry, and the magnet is immersed in the slurry and pulled (immersion pulling method). In the case of the dip-draw method, the magnet pulled up from the slurry is subjected to hot air drying or natural drying. Spraying a slurry to the magnet (spraying method) is also disclosed instead of immersing the magnet in the slurry.

In these methods, the slurry can be applied to the entire face of the magnet. Therefore, the heavy rare earth element RH can be introduced into the magnet from the entire surface of the magnet, and H after heat treatment can be further improved _cJ . However, in the dip-pulling method, the slurry is always biased toward the lower portion of the magnet due to gravity. In addition, in the spray coating method, the coating thickness of the magnet end portion becomes thicker due to the surface tension. It is difficult for any method to uniformly present the RH compound on the surface of the magnet.

When a slurry having a low viscosity is used to thin the coating layer, the non-uniformity of the thickness of the coating layer can be improved to some extent. However, since the coating amount of the slurry is reduced, H after the heat treatment cannot be greatly improved _cJ . When coating is performed a plurality of times in order to increase the coating amount of the slurry, the production efficiency is significantly lowered. Especially inWhen the spraying method is adopted, the slurry is also applied to the inner wall surface of the spraying device, and the utilization yield of the slurry is lowered. As a result, there is a problem that the heavy rare earth element RH as a rare resource is wasted.

The applicant of the present invention 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 R-T-B sintered magnet. The method of uniformly depositing these powders on the surface of R-T-B sintered magnets has not been sufficiently established.

Disclosure of Invention

Technical problem to be solved by the invention

The present invention provides a diffusion source attaching device capable of efficiently coating a diffusion source for diffusing various elements into a rare earth sintered magnet material onto the surface of the rare earth sintered magnet material, and a method for manufacturing a rare earth sintered magnet by using the diffusion source attaching device to diffuse a desired element from the magnet surface into the inside.

Technical scheme for solving technical problems

In the illustrated embodiment, the diffusion source attaching apparatus of the present invention includes: a flow tank for storing and flowing diffusion source powders attached to each of the plurality of rare earth sintered magnet raw materials; and a conveying device having 2 or more wires for placing and conveying the plurality of rare earth sintered magnet raw materials, wherein the plurality of rare earth sintered magnet raw materials can be conveyed by moving the wires in a horizontal direction so that the plurality of rare earth sintered magnet raw materials pass through a predetermined space located above the flow groove.

In one embodiment, when the plurality of rare earth sintered magnet raw materials conveyed by the conveying device pass through the predetermined space located above the flow groove, an adhesive is applied to the surface of each of the plurality of rare earth sintered magnet raw materials, and particles of the diffusion source powder floating from the flow groove into the predetermined space are attached to the adhesive.

In one embodiment, the adhesive agent is provided with a device for removing excess particles from the particles of the diffusion source powder that pass through the predetermined space and adhere to the adhesive agent by air blowing.

In a certain embodiment, the method further comprises: a flow groove accommodating chamber surrounding the flow groove, the flow groove accommodating chamber including a recovery unit for recovering the diffusion source powder overflowed from the flow groove; and a circulation mechanism for feeding the diffusion source powder recovered by the recovery unit to the flow tank.

In one embodiment, the apparatus further comprises a diffusion source powder supply device for supplying the diffusion source powder to the flow-groove housing chamber from outside the flow-groove housing chamber.

In one embodiment, the apparatus further comprises a control device for controlling the diffusion source powder supply device, and a sensor for detecting the amount or height of the diffusion source powder collected in the collection unit, wherein the control device starts to supply the diffusion source powder again from the diffusion source powder supply device to the flow tank storage chamber when it is determined that the amount or height of the diffusion source powder existing in the collection unit has decreased to a first value, and stops the supply of the diffusion source powder from the diffusion source powder supply device to the flow tank storage chamber when the amount or height of the diffusion source powder existing in the collection unit has increased to a second value larger than the first value.

In one embodiment, the circulation means includes a pipe for conveying the diffusion source powder from the recovery unit into the flow tank by an air flow.

In one embodiment, the flow groove has a porous region on a bottom surface, and the flow groove has a gas flow device for flowing gas from the porous region and blowing up the diffusion source powder in the flow groove.

In an exemplary embodiment, the method for manufacturing a rare earth sintered magnet of the present invention includes: a step of adhering the diffusion source powder to each of the plurality of rare earth sintered magnet raw materials by using the arbitrary diffusion source adhering device; and diffusing the element contained in the diffusion source powder from the diffusion source powder attached to each of the plurality of rare earth sintered magnet raw materials into the rare earth sintered magnet raw materials.

Effects of the invention

According to the embodiment of the present invention, a diffusion source attaching device capable of efficiently applying a diffusion source for diffusing various elements into a rare earth sintered magnet to the surface of a rare earth sintered magnet raw material, and a method for manufacturing a rare earth sintered magnet in which a desired element is diffused from the magnet surface into the inside by using the diffusion source attaching device are provided.

In addition, according to the embodiment of the present invention, for example, the powder particle layer containing the diffusion source of the heavy rare earth element RH or other element can be uniformly coated on the surface of the rare earth sintered magnet raw material without waste and efficiently. Therefore, the amount of elements such as rare elements used can be reduced, and the magnet performance of the rare earth sintered magnet can be improved.

Drawings

Fig. 1 is a diagram schematically showing a schematic configuration example of a diffusion source attaching apparatus 1000 according to the present embodiment.

Fig. 2 is a perspective view schematically showing a flow groove and a wire positioned thereabove.

Fig. 3 is a perspective view showing a state in which a plurality of rare earth sintered magnet raw materials are carried on a wire rod in the Y-axis direction.

Fig. 4 is a sectional view schematically showing the flow groove 100 and the wire 20 positioned thereabove.

Fig. 5 is a cross-sectional view showing a state in which a plurality of rare earth sintered magnet raw materials 10 are transported in the Y-axis direction by the wire rods 20 in a state after the diffusion source powder starts to flow in the flow grooves 100.

Fig. 6 is a flowchart showing a method for manufacturing a rare earth sintered magnet according to the present embodiment.

Description of the reference numerals

10: rare earth sintered magnet raw material; 12: an adhesive; 14: diffusing a source powder; 20: a wire rod; 30: a recovery unit; 100: a flow channel; 200: a conveying device; 300: a flow channel receiving chamber; 400: a circulation mechanism; 500: a diffusion source powder supply device; 600: a control device; 1000: a diffusion source attachment device.

Detailed Description

An embodiment of the method for producing a rare earth sintered magnet of the present invention includes: a step of adhering diffusion source powder to each of the plurality of rare earth sintered magnet raw materials using a diffusion source adhering device; and a step of diffusing the element contained in the diffusion source powder from the diffusion source powder to which each of the plurality of rare earth sintered magnet raw materials is attached into the inside of each rare earth sintered magnet raw material.

Next, a configuration example and an operation example of the diffusion source attaching apparatus according to the present embodiment will be described.

Reference is first made to fig. 1. Fig. 1 is a diagram schematically showing a schematic configuration example of a diffusion source attaching apparatus 1000 according to the present embodiment. In the figure, for reference, X-axis, Y-axis, and Z-axis are marked orthogonal to each other.

In the example of fig. 1, the diffusion source attaching device 1000 has a flow cell 100 and a conveying device 200. The flow tank 100 is a device for storing and flowing diffusion source powder 14 attached to each of a plurality of rare earth sintered magnet raw materials (workpieces) 10. The conveyor 200 has 2 or more wires 20 on which a plurality of rare earth sintered magnet raw materials 10 are placed and conveyed, and can move each wire 20 in the horizontal direction (Y-axis direction). The wire 20 is driven by a motor, for example. The conveyor 200 conveys the plurality of rare earth sintered magnet raw materials 10 so that the plurality of rare earth sintered magnet raw materials 10 pass through a predetermined space S located above the flow tank 100. The height range of the predetermined space S is, for example, a range of 5mm to 100mm from the upper end of the flow groove 100. The prescribed space S is included in a region of the diffusion source powder 14 where a fluidized bed (fluidized bed) is formed in the flow groove 100 when viewed from the front of the Z axis. The flow layer provides an air flow with a certain flow rate or more from the lower side of the powder, so that the flow resistance of the powder particles is equal to the gravity, and the powder flows like a boiling liquid. This fluidization is known as "fluidization".

Reference is next made to fig. 2 and 3. Fig. 2 is a perspective view schematically showing the flow groove 100 and the wire 20 positioned thereabove. Fig. 3 is a perspective view showing a state in which a plurality of rare earth sintered magnet raw materials 10 are mounted on a wire rod 20, and the plurality of rare earth sintered magnet raw materials 10 are transported in the Y-axis direction by the wire rod 20.

In the example shown in fig. 2, the flow tank 100 has a box shape with an open upper portion, and has 4 side portions 100S and 1 bottom portion 100B. The flow cell 100 in the illustrated example has a rectangular shape with one pair of sides parallel to the Y-axis direction and the other pair parallel to the X-axis direction when viewed in the forward direction of the Z-axis. The length of the 1-side is, for example, in the range of 100mm to 300 mm. The height of the side surface portion 100S of the flow groove 100 or the depth of the flow groove 100 is, for example, in the range of 20mm to 200 mm. However, the shape and size of the flow groove 100 are not limited to the above examples, and are arbitrary. The flow groove 100 may have a shape other than a rectangle in plan view, for example, a circular shape, an elliptical shape, or a polygonal shape.

The side surface portion 100S of the flow groove 100 may be formed of a metal plate, for example. The outer side surface of the side surface portion 100S may be inclined, and the cross section may be trapezoidal. A part or all of the bottom surface portion 100B of the flow groove 100 has a plurality of holes for circulating air. Such a bottom surface portion 100B is suitably formed of, for example, a porous plate.

The wire rod 20 is configured such that bending may occur when a plurality of rare earth sintered magnet raw materials 10 are placed, but the wire rod is not in contact with the flow groove 100 even in a state where bending occurs. When the wire rod 20 is bent due to the weight of the rare earth sintered magnet raw material 10, the inclination angle of the wire rod 20 increases, the rare earth sintered magnet raw material 10 may slide on the wire rod 20. In order to prevent such sliding, the inclination angle of the wire 20 is desirably 5 degrees or less. The diameter of the wire 20 may be, for example, in the range of 0.5mm to 2 mm.

In the example of fig. 2 and 3, the number of wires 20 running side by side is 2. The number of wires 20 is not limited to 2, but may be 3 or more.

Next, refer to fig. 4 and 5. Fig. 4 is a sectional view schematically showing the flow groove 100 and the wire 20 positioned thereabove. In the state of fig. 4, the diffusion source powder 14 is stored in the flow tank 100, but the flow is not started. Fig. 5 is a cross-sectional view showing a state in which a plurality of rare earth sintered magnet raw materials 10 are transported in the Y-axis direction by the wire rods 20 in a state after the diffusion source powder starts to flow in the flow grooves 100.

In the illustrated example, the flow cell 100 has a porous region 120 at the bottom surface. The diffusion source attaching device 1000 of this embodiment has a gas flow device 140 that causes gas to flow from the porous region 120 and blows up the diffusion source powder 14 in the flow cell 100. The gas flow from the gas flow device 140 through the porous region 120 into the flow cell 100 causes the diffusion source powder 14 in the flow cell 100 to flow to form a fluidized bed. In the embodiment of the present invention, the surface of the rare earth sintered magnet raw material 10 is attached with the diffusion source powder 14 outside (above) the flow tank 100, instead of the inside of the diffusion source powder 14 forming a flow layer inside the flow tank 100. This is because in the embodiment of the present invention, a thick particle layer is not required as long as the adhesion of 1 layer of powder particles can be uniformly achieved. Therefore, in forming the fluidized bed, the diffusion source powder 14 is preferably blown up to a height of about 10mm to 30mm from the upper surface of the fluidized bed 100.

In the present embodiment, when each of the plurality of rare earth sintered magnet raw materials 10 conveyed by the wire rod 20 of the conveying device 200 passes through the predetermined space S located above the flow groove 100, the adhesive 12 is applied to the surface of each of the plurality of rare earth sintered magnet raw materials 10. Such an adhesive 12 can be formed by applying a liquid having adhesiveness to the rare earth sintered magnet raw material 10 placed on the wire rod 20 by using a spraying device or the like. Particles 14P of the diffusion source powder 14 floating in the predetermined space S from the flow tank 100 adhere to the binder 12 of the rare earth sintered magnet raw material 10 moving in the horizontal direction. At this time, the particles 14P are directly contacted and bonded with the adhesive 12 to form 1 particle layer. But particles 14P may form another particle layer on such particle layer. However, such particles 14P constituting the other particle layer are not in direct contact with the adhesive 12 and are not adhered. Therefore, by the air blowing step performed later, the other particle layer is easily removed, and the particle layer of 1 layer can be formed in a state of actually covering the surface of the adhesive 12. This contributes to control of the adhesion of the diffusion source powder, and uniform diffusion is performed with good reproducibility, suppressing unevenness in the magnet characteristics.

In order to perform the blowing step, the diffusion source attaching device 1000 or the manufacturing equipment including the diffusion source attaching device 1000 may further include a device (not shown) for removing unnecessary particles among the particles of the diffusion source powder 14 that pass through the predetermined space S and are attached to the adhesive 12 by air blowing.

Referring again to fig. 1.

In the present embodiment, the diffusion source attaching apparatus 1000 further includes a flow tank housing chamber 300 surrounding the flow tank 100, and a circulation mechanism 400. The flow groove housing chamber 300 includes a recovery portion 30 that recovers the diffusion source powder 14 overflowed from the flow groove 100. The flow tank housing chamber 300 preferably has a funnel-shaped inclination at a lower portion thereof, and a recovery portion 30 is provided at a lower end thereof. Particles of the diffusion source powder 14 floating in the flow-groove housing chamber 300 fall by their own weight and are collected in the recovery unit 30. The circulation mechanism 400 is configured to send the diffusion source powder 14 collected by the collection unit 30 to the flow tank 100.

In the present embodiment, the circulation mechanism 400 includes a pipe 40 for conveying the diffusion source powder 14 from the recovery unit 30 into the flow tank 100 by an air flow. Specifically, by the operation of the injector E1, the air flowing through the pipe 40 conveys the diffusion source powder 14 located in the recovery portion 30 by the air flow. The injector E1 is supplied with a gas such as air pressurized by a pump, not shown, through a valve V1.

The conduit 40 communicates with the flow cell receiving chamber 300. In the flow tank housing chamber 300, the tip end of the pipe 40 is disposed so as to be able to supply the diffusion source powder 14 to the flow tank 100. A funnel-shaped relay vessel may be provided between the front end of the pipe 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 conveyed by the pipe 40 is not supplied to the flow tank 100 in large amounts at one time. The relay device functions to separate the diffusion source powder 14 from the air for conveyance and prevent the recovered diffusion source powder 14 from directly falling onto the work 10. By providing such a relay device, the attachment of the diffusion source powder 14 from the flow tank 100 to the work 10 can be stably performed, and the diffusion source powder 14 to be recovered does not change.

The diffusion source attaching device 1000 of the present embodiment includes a diffusion source powder supply device 500 that re-supplies the diffusion source powder 14 from the outside of the flow tank housing chamber 300 to the inside of the flow tank housing chamber 300. As described above, by the particles 14P of the diffusion source powder 14 blown up from the flow tank 100 adhering to the binder 12 of the rare earth sintered magnet raw material 10 passing above the flow tank 100, the amount of the diffusion source powder 14 existing inside the flow tank accommodating chamber 300 gradually decreases. The particles 14P of the diffusion source powder 14 overflowing from the flow tank 100 are recovered and returned to the flow tank 100 by the operation of the circulation mechanism 400, but when the amount of the diffusion source powder 14 existing inside the flow tank accommodating chamber 300 decreases, the particles 14P of the recovered diffusion source powder 14 are naturally also decreased, and the diffusion source powder 14 stored in the flow tank 100 is insufficient. The diffusion source powder supply device 500 supplies new diffusion source powder 14 into the flow-groove housing chamber 300 so that the diffusion source powder 14 stored in the flow groove 100 is sufficiently supplied. This supply is performed by ejecting the diffusion source powder stored in the diffusion source powder supply device 500 into the flow groove housing chamber 300 through a pipe by the ejector E2. The injector E2 is supplied with a gas such as pressurized air via a valve V2.

The diffusion source attaching device 1000 of the present embodiment includes a control device 600 that controls the diffusion source powder supply device 500, and a sensor 52 that detects the amount or height of the diffusion source powder 14 collected in the collection unit 30. The control device 600 is constituted by a computer and has a processor and a storage device. Processors are 1 or more semiconductor integrated circuits, also known as Central Processing Units (CPUs) or microprocessors. The processor successively executes the computer programs stored in the storage device to realize the intended processing. This process may also be performed by a programmable logic controller (Programmable Logic Controller, PLC).

When it is determined that the amount or height of the diffusion source powder 14 existing in the recovery unit 30 has decreased to reach the first value, the control device 600 starts to supply the diffusion source powder 14 again from the diffusion source powder supply device 500 to the flow tank 100. When the amount or height of the diffusion source powder 14 existing in the recovery unit 30 increases and reaches a second value larger than the first value, the control device 600 stops the supply of the diffusion source powder 14 from the diffusion source powder supply device 500 to the flow-groove housing 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 is supplied to the flow tank 100 by the operation of the circulation mechanism 400.

The sensor 52 may include two height detectors disposed at different height positions. Such a height detector may have a structure in which a light emitting portion and a light receiving portion are arranged so as to sandwich a space in the collecting portion 30, for example. 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, and thus it can be determined that the height of the diffusion source powder 14 existing in the recovery unit 30 reaches a predetermined height. Examples of the sensor 52 include a photoelectric sensor, an ultrasonic sensor, a laser sensor, and a pulse vibration type level sensor. Among these sensors, a pulse vibration type level sensor is preferable from the viewpoint of accurately detecting the height of the powder particles of the diffusion source powder 14. According to the present embodiment, the particles 14P of the diffusion source powder 14 can be stably attached to the binder 12 of the rare earth sintered magnet raw material 10. Since the timing and the supply amount of the new diffusion source powder 14 to the flow tank housing chamber 300 are monitored based on the amount of the diffusion source powder 14 in the recovery portion 30, the necessary amount of the diffusion source powder can be maintained and controlled without providing other expensive sensors.

Hereinafter, an embodiment of the method for producing a rare earth sintered magnet according to the present invention will be described. The diffusion source attaching apparatus 1000 described above can attach various diffusion source powders to the rare earth sintered magnet raw material, and the composition of the diffusion source powders is not limited. Here, an embodiment of a method for producing an R-T-B sintered magnet including a step of adhering a diffusion source powder containing a heavy rare earth element by using the diffusion source adhering apparatus will be described.

Method for producing R-T-B sintered magnet

As shown in fig. 6, the method of manufacturing a rare earth sintered magnet of the present embodiment may include: a step S10 of preparing an R1-T-B sintered magnet material, a step S20 of preparing a diffusion source powder such as an R2-M alloy, an adhesive application step S30 of applying an adhesive to the surface of the R1-T-B sintered magnet material, a diffusion source powder attachment step S40 of attaching the diffusion source powder to the surface of the R1-T-B sintered magnet material, and a diffusion step S50. The diffusion step S50 is a heat treatment step of heating the R1-T-B sintered magnet material having the diffusion source powder of the R2-M alloy attached to the surface thereof, for example, in a vacuum or inert gas atmosphere at a temperature of 700 ℃ to 1100 ℃ inclusive, and diffusing R2 and M into the R1-T-B sintered magnet material. In the present invention, the rare earth sintered magnet before and during the diffusion process may be referred to as "R1-T-B sintered magnet material", and the rare earth sintered magnet after the diffusion process may be referred to as "R-T-B sintered magnet". These steps are described in more detail below.

(step of preparing R1-T-B sintered magnet Material)

First, the composition of the R1-T-B sintered magnet material will be described.

The R1-T-B sintered magnet material has the following composition, for example.

R1:26.6mass% to 31.5mass% (R1 is a rare earth element),

b:0.8 to 1.0mass%, preferably 0.88 to 0.97mass%,

m:0mass% or more and 1.0mass% or less (M is at least one selected from Ga, cu, zn and Si), M1:0mass% or more and 2.0mass% or less (M1 is at least 1 selected from Al, ti, V, cr, mn, ni, zr, nb, mo, ag, in, sn, hf, ta, W, pb and Bi),

the balance is composed of T (T is Fe or Fe and Co) and unavoidable impurities.

Next, a method for preparing R1-T-B sintered magnet materials will be described.

First, after preparing an alloy for an R-T-B sintered magnet, the alloy is coarsely pulverized by, for example, a hydrogen pulverizing method or the like.

Example a method for producing an alloy for R-T-B sintered magnets. The alloy ingot may be obtained by an ingot casting method in which a metal or alloy previously adjusted to the above composition is melted and added to a mold to solidify it. Alternatively, an alloy may be produced by a strip casting method in which a molten metal or alloy having the composition previously adjusted is brought into contact with a single roll, twin rolls, a rotating disc, a rotating cylinder mold, or the like, and quenched to produce a quenched solidified alloy. Further, a sheet (flag) shaped alloy may be produced by other quenching methods such as centrifugal casting.

In the embodiment of the present invention, an alloy produced by either an ingot casting method or a quenching method may be used, but an alloy produced by a quenching method such as a strip casting method is preferably used. The thickness of the alloy produced by quenching is usually in the range of 0.03mm to 1mm, and is in the form of a sheet. The hydrogen pulverized powder (coarse pulverized powder) can be made to have a size of, for example, 1.0mm or less by hydrogen pulverizing the obtained alloy. The thus obtained coarsely pulverized powder was pulverized by a jet mill.

The jet mill pulverization is carried out under an inert atmosphere such as nitrogen. The pulverization may be performed by, for example, a jet mill in a humidified atmosphere.

The fine powder used for producing the R1-T-B sintered magnet material may be produced from one material alloy (single material alloy) or may be produced by a method (blending method) in which two or more material alloys are mixed.

In a preferred embodiment, the powder compact is produced from the fine powder by pressurizing in a magnetic field, and then sintered. When the pressure is applied in a magnetic field, it is preferable to form the powder compact by pressure in an inert gas atmosphere or wet pressure from the viewpoint of suppressing oxidation. In particular, in wet pressurization, the surfaces of particles constituting the powder compact are covered with an oil agent or the like, and contact with oxygen or water vapor in the atmosphere is suppressed. Therefore, the particles can be prevented or suppressed from being oxidized by the atmosphere before and after the pressurizing step or during the pressurizing step. Therefore, the oxygen content can be easily controlled within a predetermined range. When wet pressurization in a magnetic field is performed, a slurry in which a dispersion medium is mixed with fine powder is prepared, and the slurry is supplied into a cavity in a die of a wet pressurization device and is subjected to pressurization molding in the magnetic field.

Next, the molded body was sintered to obtain an R1-T-B sintered magnet material. The sintering of the molded article is preferably 0.13Pa (10 ^－3 Torr) is less than or equal to, more preferably 0.07Pa (5.0X10) ^－4 Torr) and under a pressure of 1000 to 1150 ℃. In order to prevent oxidation by sintering, the residual gas in the atmosphere may be replaced with inert gas such as helium or argon. The obtained sintered body (R1-T-B-based sintered magnet material) may be subjected to heat treatment. The heat treatment conditions such as the heat treatment temperature and the heat treatment time may be known.

(step of preparing diffusion Source powder)

In this embodiment, for example, a powder of an R2-M alloy is used as the diffusion source powder. R2 in the R2-M alloy is a rare earth element, at least one of Tb and Dy, and at least one of Nd and Pr are necessarily contained, and M is at least one selected from Cu, ga, fe, co, ni and Al. Preferably, R2 is 65 to 97mass% of the entire R2-M alloy, and M is 3 to 35mass% of the entire R2-M alloy. More preferably, R2 is 85 to 95mass% of the entire R2-M alloy, and M is 5 to 15mass% of the entire R2-M alloy. Can obtain higher H _cJ . The content of Tb and Dy in R2 is preferably 3mass% or more and 24 mass% or less of the entire R2-M alloy. The content of Pr in R2 is preferably 65 to 86mass% based on the entire R2-M alloy. In addition, M preferably must contain at least one of Ga and Cu. Can obtain higher H _cJ . The content of Pr in the R2-M alloy is preferably 50mass% or more based on the entire R2, and more preferably R2 is composed of only Pr and Tb. By containing Pr, diffusion in the grain boundary phase is easy to proceed, and therefore Tb can be made more efficientDiffusion to the ground can obtain higher H _cJ 。

Next, a method for producing an R2-M alloy will be described.

The R2-M alloy can be prepared by a method for producing a raw alloy used in a usual method for producing an R-T-B sintered magnet, for example, a die casting method, a ribbon casting method, a single-roll super-quenching method (melt spinning method), or an atomizing method. The R2-M alloy may be obtained by pulverizing the above-obtained alloy by a known pulverizing device such as a pin mill. The R2-M alloy of the present embodiment has a powder form as a particle aggregate. The diffusion source is not limited to the R2-M-based alloy, and may include other types of alloys or compounds instead of or in addition to the R2-M-based alloy.

(adhesive coating step)

In this embodiment, the adhesive application step is performed before the diffusion source powder attachment step.

Examples of the binder applied to the surface of the R1-T-B sintered magnet material include PVA (polyvinyl alcohol), PVB (polyvinyl butyral), PVP (polyvinyl pyrrolidone), and the like. In the case where the binder is an aqueous binder, the R1-T-B sintered magnet raw material may be preheated before coating. The purpose of the preheating is to remove excess solvent to control adhesion and to allow uniform adhesion of the adhesive. The heating temperature is preferably 60 to 100 ℃. In the case of an organic solvent-based adhesive having high volatility, this step may be omitted.

The method of applying the adhesive to the surface of the R1-T-B sintered magnet material may be any method. Specific examples of the application include a spraying method, a dipping method, and application by dispensing. In a preferred embodiment, an adhesive is applied to the entire surface (entire surface) of the R1-T-B sintered magnet material. The adhesive may be applied not entirely but locally to the surface of the R1-T-B sintered magnet material. In particular, when the thickness of the R1-T-B sintered magnet material is small (for example, about 2 mm), the diffusion source powder may be attached to only one surface having the largest surface area among the surfaces of the R1-T-B sintered magnet material, so that the necessary elements may be diffused throughout the magnet. According to the manufacturing method of the present invention, the diffusion source powder can be attached to a plurality of surfaces having different normal directions in the surface of the R1-T-B sintered magnet material in one step. The thickness of the adhesive layer is preferably 10 μm to 100 μm.

(diffusion Source powder attachment Process)

In the present embodiment, a diffusion source attaching device 1000 shown in fig. 1 is used to attach diffusion source powder of an R2-M-based alloy to the surface of an R1-T-B-based sintered magnet raw material.

At this time, as shown in fig. 5, the attachment of the diffusion source powder is completed in the process in which the R1-T-B-based sintered magnet raw material is conveyed by the wire rod 20. The wire rod 20 of the present embodiment has a conveying speed of 500 mm/min to 2000 mm/min, and the time required for attaching the diffusion source powder to the 1R 1-T-B sintered magnet material is only about 1 to 2 seconds. Further, since the diffusion source powder is attached in a state where the R1-T-B sintered magnet material is supported by the fine wire rod, the diffusion source powder can be attached uniformly to substantially the entire surface of the R1-T-B sintered magnet material.

In the present embodiment, the bottom area of the recovery unit 30 is 2700mm ² . The control device 600 is configured to supply the diffusion source powder 14 from the diffusion source powder supply device 500 to the flow-groove housing chamber 300 when the height of the diffusion source powder 14 existing in the recovery portion 30 decreases and reaches a first value (85 mm), and to stop the supply when the height of the diffusion source powder 14 increases and reaches a second value (140 mm). Accordingly, the amount of the diffusion source powder 14 in the flow tank 100 is maintained within an appropriate range, and uneven deposition in the diffusion source deposition step can be suppressed, thereby achieving highly uniform deposition.

(diffusion Process)

Heating R1-T-B sintered magnet material having R2-M alloy adhered to the surface thereof as a diffusion source powder at 700-1100 ℃ in a vacuum or inert gas atmosphere to diffuse R2 and M into the R1-T-B sintered magnet material,and performing a diffusion process. Thus, a liquid phase containing R2 and M is formed from the R2-M alloy, and the liquid phase is diffused from the surface of the sintered body to the inside via the grain boundary in the R1-T-B sintered magnet material. In this case, the content of the heavy rare earth element RH (preferably Tb) contained in the R1-T-B sintered magnet material is preferably increased in an extremely small amount of 0.05mass% to 0.30 mass%. Thus, the consumption of heavy rare earth element RH can be suppressed, and extremely high H can be obtained _cJ Improving the effect. In order to increase the RH content of the R1-T-B sintered magnet material by 0.05mass% to 0.30mass%, various conditions such as the amount of the R2-M alloy, the heating temperature during the treatment, the particle size (in the case where the R2-M alloy is in the form of particles), the treatment time, and the like can be adjusted. Among these, the amount of the heavy rare earth element RH introduced (the amount to be increased) can be controlled relatively easily by adjusting the amount of the R2-M-based alloy and the heating temperature at the time of treatment.

In the present specification, for example, "to increase the content of Tb by 0.05mass% or more and 0.30mass% or less" means to increase the value by 0.05 to 0.30mass% when the content is expressed as mass%. For example, when the content of Tb of the R1-T-B sintered magnet material before the diffusion step is 0.50mass% and the content of Tb of the R-T-B sintered magnet after the diffusion step is 0.60mass%, the content of Tb is increased by 0.10mass% by the diffusion step. Whether or not the content (RH amount) of at least one of Tb and Dy is increased by 0.05mass% or more and 0.30mass% or less can be calculated by measuring the RH amounts of the R1-T-B sintered magnet material before the diffusion step and the R-T-B sintered magnet as a whole after the diffusion step, respectively, and determining how much the RH amount is increased before and after the diffusion step. In the case where an enriched portion of the R2-M alloy is present on the surface of the R-T-B sintered magnet after diffusion, it is preferable to measure the RH amount after removing the enriched portion by cutting or the like.

When the heating temperature is lower than 700 ℃, for example, the amount of the liquid phase containing Tb, pr and M is too small, high H cannot be obtained _cJ . On the other hand, when the temperature exceeds 1100 ℃, H _cJ May be reduced. Preferably 850 ℃ to 980 ℃. Can obtain higher H _cJ 。

In addition, a powder of a heavy rare earth element RH such as fluoride, oxide, or oxyfluoride may be attached to the surface of the R-T-B sintered magnet material together with a diffusion source powder of an R2-M alloy. This allows the light rare earth elements RL and M to be simultaneously diffused into the R-T-B sintered magnet material together with the heavy rare earth element RH. Examples of the fluoride, oxide, or oxyfluoride of the heavy rare earth element RH include TbF ₃ 、DyF ₃ 、Tb ₂ O ₃ 、Dy ₂ O ₃ 、Tb ₄ OF、Dy ₄ OF。

(Heat treatment step)

The R-T-B sintered magnet after the diffusion treatment step may be heat-treated at a temperature of 450 ℃ to 750 ℃ inclusive and lower than the temperature at which the diffusion treatment is performed in a vacuum or an inert gas atmosphere. By heat treatment, high H can be obtained _cJ 。

Industrial applicability

Embodiments of the present invention can enhance H of R-T-B sintered magnets with less heavy rare earth element RH _cJ Therefore, the method can be used for manufacturing rare earth sintered magnets requiring high coercivity. The present invention can be widely used for a technique that requires diffusing a metal element other than the heavy rare earth element RH from the surface to the rare earth sintered magnet.

Claims

1. A diffusion source attachment device, comprising:

a flow tank for storing and flowing diffusion source powders attached to each of the plurality of rare earth sintered magnet raw materials; and

and a conveying device having 2 or more wires for placing and conveying the plurality of rare earth sintered magnet raw materials, wherein the plurality of rare earth sintered magnet raw materials can be conveyed by moving the wires in a horizontal direction so that the plurality of rare earth sintered magnet raw materials pass through a predetermined space located above the flow groove.

2. The diffusion source attaching apparatus according to claim 1, wherein,

when the plurality of rare earth sintered magnet raw materials conveyed by the conveying device pass through the predetermined space located above the flow groove, an adhesive is coated on the surface of each of the plurality of rare earth sintered magnet raw materials, and particles of the diffusion source powder floating from the flow groove into the predetermined space can be attached to the adhesive.

3. A diffusion source attaching apparatus according to claim 2, wherein,

and means for removing, by air blowing, unnecessary particles among the particles of the diffusion source powder passing through the prescribed space and adhering to the adhesive.

4. A diffusion source attachment device according to any one of claims 1 to 3, further comprising:

a flow tank housing chamber surrounding the flow tank, the chamber including a recovery unit for recovering the diffusion source powder overflowed from the flow tank; and

and a circulation mechanism for sending the diffusion source powder recovered by the recovery unit to the flow tank.

5. A diffusion source attaching apparatus according to claim 4, wherein,

the apparatus includes a diffusion source powder supply device for re-supplying the diffusion source powder from outside the flow-groove housing chamber to the flow-groove housing chamber.

6. A diffusion source attaching apparatus according to claim 5, wherein,

comprises a control device for controlling the diffusion source powder supply device, and a sensor for detecting the amount or height of the diffusion source powder recovered to the recovery part,

when the control device judges that the amount or height of the diffusion source powder existing in the recovery part is reduced and reaches a first value, the control device starts to supply the diffusion source powder from the diffusion source powder supply device to the flow groove accommodating chamber again,

when the amount or height of the diffusion source powder existing in the recovery portion increases and reaches a second value larger than the first value, the supply of the diffusion source powder from the diffusion source powder supply device to the flow groove housing chamber is stopped.

7. A diffusion source attaching apparatus according to any one of claims 4 to 6,

the circulation mechanism has a pipe for transporting the diffusion source powder from the recovery unit into the flow tank by an air flow.

8. The diffusion source attaching apparatus according to any one of claims 1 to 7, wherein,

a porous region is provided at the bottom surface of the flow cell,

the diffusion source attaching means has gas flow means for flowing gas from the porous region and blowing up the diffusion source powder in the flow cell.

9. A method for manufacturing a rare earth sintered magnet, comprising:

a step of adhering the diffusion source powder to each of the plurality of rare earth sintered magnet raw materials using the diffusion source adhering apparatus according to any one of claims 1 to 8; and

and diffusing the element contained in the diffusion source powder from the diffusion source powder attached to each of the plurality of rare earth sintered magnet raw materials into each rare earth sintered magnet raw material.