Method for manufacturing re-fe-b-based sintered magnet by using dry coating and re-fe-b-based sintered magnet manufactured thereby

Abstract

Disclosed are a method for manufacturing an RE-Fe-B-based sintered magnet by using dry coating, and an RE-Fe-B-based sintered magnet manufactured thereby. The present invention is characterized by comprising the steps of: applying a binder to a first surface of an RE-Fe-B-based sintered magnet and attaching rare-earth diffusion powder thereto; applying a binder to a second surface of the RE-Fe-B-based sintered magnet and attaching rare earth diffusion powder thereto; and heat-treating the RE-Fe-B-based sintered magnet to diffuse the rare earth diffusion powder into the RE-Fe-B-based sintered magnet.

Description

Method for manufacturing RE-FE-B type sintered magnet using dry coating and RE-FE-B type sintered magnet manufactured thereby

[0001] The present invention relates to a method for manufacturing a RE-Fe-B sintered magnet using dry coating capable of improving the performance of the magnet, and to a RE-Fe-B sintered magnet manufactured thereby.

[0002] Nd-Fe-B magnets are made of Nd2Fe, a compound of the rare earth elements neodymium (Nd) and iron and boron (B). 14 As a permanent magnet with a composition of B, it has been used as a general-purpose permanent magnet for 30 years since its development in 1983. These Nd-Fe-B magnets are used in various fields such as electronic information, automobile industry, medical devices, energy, and transportation.

[0003] In particular, in line with the recent trend toward lightweight and miniaturization, it is being used in products such as machine tools, electronic information devices, home appliances, mobile phones, robot motors, wind power generators, small motors for automobiles, and drive motors.

[0004] Heavy rare earth sintered magnets, such as Nd-Fe-B magnets, utilize the grain boundary diffusion process (GBDP) to improve coercivity performance. Heavy rare earth diffusion materials are applied to the magnet surface, and the performance is improved by diffusing the heavy rare earth into the grain boundaries through GBDP. Generally, the heavy rare earth diffusion materials are heat-treated by applying substances such as Tb and Dy, thereby increasing the coercivity.

[0005] However, the conventional dipping coating method and spray coating method for manufacturing Nd-Fe-B type magnets have difficulty in suppressing lateral diffusion because the heavy rare earth diffusion material diffuses to the side surface of the magnet, causing most of the heavy rare earth to aggregate on the main surface of the magnet, and as a result, the heavy rare earth is consumed on the surface of the magnet, and the lateral diffusion must be suppressed due to the shallow diffusion depth of the heavy rare earth.

[0006] Therefore, it is necessary to invent a new magnet manufacturing method that can solve the problems of lateral diffusion suppression and slurry waste of the conventional dipping coating method and spray coating method, and exhibit higher magnetic properties compared to the amount of coating through effective lateral diffusion suppression.

[0007]

[0008] One object of the present invention is to provide a method for manufacturing a RE-Fe-B sintered magnet using dry coating capable of improving the performance of the magnet, and a RE-Fe-B sintered magnet manufactured thereby.

[0009] One object of the present invention is to provide a method for manufacturing a RE-Fe-B sintered magnet using dry coating that can simplify the grain boundary diffusion process (GBDP), and a RE-Fe-B sintered magnet manufactured thereby.

[0010]

[0011] A method for manufacturing a RE-Fe-B sintered magnet using dry coating according to one embodiment of the present invention includes the steps of: applying a binder to a first surface of a RE-Fe-B sintered magnet and attaching a rare earth diffusion powder; applying a binder to a second surface of the RE-Fe-B sintered magnet and attaching a rare earth diffusion powder; and heat-treating the RE-Fe-B sintered magnet to diffuse the rare earth diffusion powder into the interior of the RE-Fe-B sintered magnet; wherein the RE-Fe-B sintered magnet is characterized in that the binder is applied using dry coating and the rare earth diffusion powder is attached.

[0012] In one embodiment, the dry coating may be any one of stamping, vacuum deposition, ion plating, and sputtering.

[0013] In one embodiment, the stamping method may utilize a dry coating mold.

[0014] In one embodiment, the stamping method can be used to control the application of the rare earth diffusion powder to the side of the RE-Fe-B sintered magnet.

[0015] In one embodiment, the binder may be either polyvinyl alcohol (PVA) or polyvinyl chloride (PVC).

[0016] In one embodiment, the thickness of the binder may be 10 μm to 50 μm.

[0017] In one embodiment, the rare earth diffusion powder is TbH x and DyH x (x is the number of atoms, 1≤x≤3) It can be any one of the following.

[0018] In one embodiment, the size of the rare earth diffusion powder may be from 30 μm to 53 μm.

[0019] In one embodiment, the thickness of the rare earth diffusion powder may be 80 μm to 150 μm.

[0020] In one embodiment, the step of heat-treating the RE-Fe-B sintered magnet to diffuse the rare earth diffusion powder into the interior of the RE-Fe-B sintered magnet may include a first heat treatment step performed at a heat treatment temperature of 800°C to 1000°C; and a second heat treatment step performed at a heat treatment temperature of 400°C to 600°C.

[0021] In one embodiment, the first heat treatment time may be 2 to 6 hours, and the second heat treatment time may be 2 to 6 hours.

[0022] According to one embodiment, the RE-Fe-B sintered magnet includes a rare earth alloy phase in which rare earth diffusion powder is diffused into grain boundaries within an RE-Fe-B substrate (wherein RE includes at least one of Nd, Pr, La, Ce, Y, Gd, Ho, Dy, and Tb) through grain boundary diffusion treatment, and the rare earth alloy phase can be represented by the following chemical formula 1.

[0023] [Chemical Formula 1]

[0024] (HR)2Fe 14 B

[0025] (In the above chemical formula 1, the HR includes at least one of Dy and Tb)

[0026]

[0027] According to one embodiment of the present invention, a method for manufacturing a RE-Fe-B sintered magnet using dry coating, which can perform a grain boundary diffusion process (GBDP) by attaching rare earth diffusion powder through a relatively simple process, and an RE-Fe-B sintered magnet manufactured thereby can be provided.

[0028] According to one embodiment of the present invention, by attaching rare earth diffusion powder to the upper and lower surfaces of a magnet using dry coating in the form of a stamping method, which is a stamping method, the rare earth diffusion powder can be effectively suppressed from being applied to the side surfaces of the magnet, thereby providing improved magnetic properties. A method for manufacturing a RE-Fe-B sintered magnet using dry coating and an RE-Fe-B sintered magnet manufactured thereby can be provided.

[0029] According to one embodiment of the present invention, a binder is applied to a magnet surface, and rare earth diffusion powder is directly attached on the applied binder, thereby securing improved magnetic properties compared to a relatively small amount of application, and a method for manufacturing a RE-Fe-B sintered magnet using dry application that can solve the problems of slurry waste and oxidation, which are problems of the existing dipping application method, and an RE-Fe-B sintered magnet manufactured thereby can be provided.

[0030] According to one embodiment of the present invention, a method for manufacturing a RE-Fe-B sintered magnet using dry coating, which can uniformly attach a large amount of rare earth diffusion powder by performing dry coating using a stamping method using a dry coating mold, and an RE-Fe-B sintered magnet manufactured through the dry coating method can be provided.

[0031]

[0032] FIG. 1 is a schematic diagram illustrating a method for manufacturing a RE-Fe-B sintered magnet using dry coating according to one embodiment of the present invention.

[0033] FIG. 2 is a flowchart illustrating a method for manufacturing a RE-Fe-B sintered magnet using dry coating according to one embodiment of the present invention.

[0034] Figure 3 is a graph showing the upper surface of a dry coating mold.

[0035] Figure 4 is a graph showing the side view of a dry coating mold.

[0036] Figure 5 is an image of a dry application method using a dry application mold.

[0037] Figure 6 is a schematic diagram illustrating Comparative Example 1 and Example 1.

[0038] Figure 7 is an image of a RE-Fe-B sintered magnet according to Comparative Example 1 and Example 1.

[0039] Figure 8a shows the intrinsic coercivity (H) of RE-Fe-B sintered magnets according to comparative example 1 and example 1. cj) is a graph showing the residual flux density (B r ) is a graph showing the maximum energy ((BH) max )) is a graph showing the

[0040] Figure 9a shows the intrinsic coercivity (H) of RE-Fe-B system sintered magnets according to Comparative Example 1-1, Comparative Example 1-2, Example 1-1, Example 1-2, and Example 1-3. cj ) is a graph showing the residual flux density (B r ) is a graph showing the maximum energy ((BH) max )) is a graph showing the

[0041] Figure 9d shows the coercivity (H) of RE-Fe-B system sintered magnets according to Comparative Example 1-1, Comparative Example 1-2, Example 1-1, Example 1-2, and Example 1-3. cb ) is a graph illustrating the magnetic field (H k ) is a graph showing the aspect ratio (H k / H cj ) is a graph showing the

[0042] Fig. 10a is a graph showing the magnetization curve of a basic magnet, Fig. 10b is a graph showing the magnetization curve of Comparative Example 1-1, and Fig. 10c is a graph showing the magnetization curve of Comparative Example 1-2.

[0043] FIG. 10d is a graph showing a magnetization curve of Example 1-1, FIG. 10e is a graph showing a magnetization curve of Example 1-2, and FIG. 10f is a graph showing a magnetization curve of Example 1-3.

[0044] Figures 10g and 10h are graphs showing the magnetization curve of a blank magnet.

[0045] Figure 11 is an image illustrating the properties of the RE-Fe-B sintered magnet used in Figures 7 to 10h.

[0046] Figure 12 is a schematic diagram illustrating comparative example 2.

[0047] Figure 13 is an image of a RE-Fe-B sintered magnet according to Comparative Example 2.

[0048] Figure 14 is an image of a RE-Fe-B sintered magnet according to Comparative Example 2 and Example 2.

[0049] Figure 15a shows the intrinsic coercivity (H) of RE-Fe-B sintered magnets according to comparative example 2 and example 2. cj ) is a graph showing the residual flux density (B r ) is a graph showing the maximum energy ((BH) max )) is a graph showing the

[0050] Fig. 16 is an image illustrating the properties of the RE-Fe-B sintered magnet used in Figs. 13 to 15c.

[0051]

[0052] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings and the contents described in the attached drawings, but the present invention is not limited or restricted by the embodiments.

[0053] The terminology used herein is for the purpose of describing embodiments and is not intended to limit the present invention. In this specification, the singular includes the plural unless specifically stated otherwise. The terms "comprises" and / or "comprising" as used herein do not exclude the presence or addition of one or more other components or steps.

[0054] The terms “embodiment,” “example,” “aspect,” “example,” and the like as used herein are not to be construed as implying that any aspect or design described is better or advantageous over other aspects or designs.

[0055] Also, the term 'or' implies an inclusive or rather than an exclusive or. That is, unless stated otherwise or clear from the context, the expression 'x utilizes a or b' means any one of the natural inclusive permutations.

[0056] Additionally, as used in this specification and claims, the singular forms “a” or “an” should generally be construed to mean “one or more” unless otherwise indicated or clear from the context to be in the singular form.

[0057] The terms used in the following description have been selected as common and universal in the relevant technical fields. However, other terms may be used depending on technological developments and / or changes, customs, and the preferences of technicians. Therefore, the terms used in the following description should not be construed as limiting the technical concepts, but rather as exemplary terms used to describe the embodiments.

[0058] Additionally, in certain cases, the applicant may arbitrarily select terms, in which case their detailed meanings will be described in the relevant description. Therefore, the terms used in the following description should be understood not simply as names, but based on their inherent meaning and the overall context of the specification.

[0059] Unless otherwise defined, all terms (including technical and scientific terms) used herein may be used in their common sense to those of ordinary skill in the art to which the present invention pertains. Furthermore, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0060] Meanwhile, when describing the present invention, if a detailed description of a related known function or configuration is judged to unnecessarily obscure the gist of the present invention, such detailed description will be omitted. Furthermore, the terminology used in this specification is intended to appropriately express embodiments of the present invention and may vary depending on the intent of the user or operator, or the customary practices in the field to which the present invention pertains. Therefore, the definitions of these terms should be based on the contents throughout this specification.

[0061]

[0062] FIG. 1 is a schematic diagram illustrating a method for manufacturing a RE-Fe-B sintered magnet using dry coating according to one embodiment of the present invention, and FIG. 2 is a flowchart illustrating a method for manufacturing a RE-Fe-B sintered magnet using dry coating according to one embodiment of the present invention.

[0063] A method for manufacturing a RE-Fe-B sintered magnet (130) using dry coating according to one embodiment of the present invention includes a step (S110) of applying a binder (10) to a first surface of a RE-Fe-B sintered magnet mother body (100) and attaching a rare earth diffusion powder (20), a step (S120) of applying a binder (10) to a second surface of the RE-Fe-B sintered magnet (110) including a first attachment surface and attaching a rare earth diffusion powder (20), and a heat treatment step (S130) of heating the RE-Fe-B sintered magnet (120) including the first and second attachment surfaces to diffuse the binder into the magnet.

[0064] In particular, the method for manufacturing a RE-Fe-B sintered magnet (130) using dry coating according to one embodiment of the present invention can improve the performance of the RE-Fe-B sintered magnet (130) by supplementing the conventional dipping coating method using slurry by attaching a binder (10) and a rare earth diffusion powder (20) using dry coating, and solving the problems of lateral diffusion suppression, slurry waste, and oxidation.

[0065] First, a method for manufacturing a RE-Fe-B sintered magnet (130) using dry coating according to one embodiment of the present invention includes a step (S110) of applying a binder (10) to a first surface of a RE-Fe-B sintered magnet mother body (100) and attaching rare earth diffusion powder (20).

[0066] Specifically, a binder (10) can be applied to the first surface of a RE-Fe-B sintered magnet mother body (100) using a dry application method, and a rare earth diffusion powder (20) can be attached to the applied binder (10) using a dry application method.

[0067] The dry application method may be any one of stamping, vacuum deposition, ion plating, and sputtering, and preferably, the stamping method.

[0068] A method for manufacturing a RE-Fe-B sintered magnet (130) using dry coating according to one embodiment of the present invention uses dry coating of a stamping method in the form of stamping through a dry coating mold, thereby attaching rare earth diffusion powder (20) to the upper and lower surfaces of the magnet, thereby effectively suppressing the rare earth diffusion powder (20) from being applied to the side surfaces of the magnet, and thereby manufacturing an RE-Fe-B sintered magnet using dry coating that can provide improved magnetic properties.

[0069]

[0070] Fig. 3 is a graph showing the upper surface of a dry coating mold, Fig. 4 is a graph showing the side surface of a dry coating mold, and Fig. 5 is an image of a dry coating method using a dry coating mold.

[0071] Using the dry coating mold of FIGS. 3 and 4, a binder (10) can be applied to the first surface of the RE-Fe-B sintered magnet mother body (100), and rare earth diffusion powder (20) can be attached.

[0072] Referring to FIGS. 3 and 4, the dry coating mold is used as a large-capacity mold rather than one for applying a single magnet, so that a binder (10) can be applied to a large number of magnets with one stamping, and rare earth diffusion powder (20) can be attached to the applied binder (10). Therefore, rare earth diffusion powder (20) can be uniformly attached to a large number of magnets at once using the dry coating mold.

[0073] In particular, the conventional dipping coating method has a problem in that the thickness of the rare earth alloy coating layer is formed differently depending on the coating speed during coating, resulting in a decrease in coating uniformity and productivity.

[0074] However, referring to FIG. 5, a method for manufacturing a RE-Fe-B sintered magnet (130) using dry coating according to one embodiment of the present invention applies a stamping method of stamping a binder (10) and a rare earth diffusion powder (20) like a stamp on a first surface of a RE-Fe-B sintered magnet mother body (100) using dry coating, thereby improving coating uniformity and enabling large-scale manufacturing, thereby improving productivity.

[0075] Specifically, the method for manufacturing a RE-Fe-B sintered magnet (130) using dry coating according to one embodiment of the present invention can solve the problem of the thickness of the coating layer varying in the conventional dipping coating method by manufacturing a dry coating mold and performing the coating process, thereby enabling the formation of a uniform coating layer of rare earth diffusion powder (20).

[0076] If the coating process is carried out without using a dry coating mold, rare earth diffusion powder may be coated on the side of the magnet, and when coating the side, the diffusion depth may be reduced and the diffusion source may be consumed by agglomeration inside the main body of the magnet surface, which may cause a problem of deterioration in magnetic properties.

[0077] In addition, a method for manufacturing a RE-Fe-B sintered magnet (130) using dry coating according to an embodiment of the present invention can apply rare earth diffusion powder (20) in the form of dry powder to the upper and lower surfaces of the RE-Fe-B sintered magnet (130) using a stamping method, and can be mixed with a small amount of ethanol to make it into a clay form and apply it to the upper and lower surfaces of the RE-Fe-B sintered magnet (130). For example, when applying it in the form of clay, 5 ml to 10 ml of ethanol can be mixed per 100 g of rare earth diffusion powder (20), and through this, scattering of the rare earth diffusion powder (20) can be suppressed, but there is a problem in that it is difficult to control the application amount of the fine rare earth diffusion powder (20).

[0078] Accordingly, according to one embodiment of the present invention, when the rare earth diffusion powder (20) is applied in the form of dry powder to the upper and lower surfaces of the RE-Fe-B sintered magnet (130) using a stamping method, the amount of application can be finely controlled because the rare earth diffusion powder (20) is attached in the form of dry powder, so there is an advantage in that it does not cause a decrease in the performance of the magnet that may occur due to excessive application of the rare earth diffusion powder (20) to the upper and lower surfaces of the RE-Fe-B sintered magnet (130).

[0079] Therefore, the method for manufacturing a RE-Fe-B sintered magnet (130) using dry coating according to one embodiment of the present invention can prevent side coating of the magnet by coating only the upper and lower surfaces of the RE-Fe-B sintered magnet (130) using the dry coating method, thereby solving the problem of deterioration of the magnetic properties of the side coating.

[0080] In addition, the dry coating method can provide the effect of not only improving magnetic properties but also facilitating process application in a vacuum gas atmosphere.

[0081] The existing dipping coating method has a problem in that it is difficult to proceed in a vacuum or ethanol atmosphere, and the method for manufacturing a RE-Fe-B sintered magnet (130) using dry coating according to one embodiment of the present invention can effectively suppress oxidation when coating is performed under a vacuum and argon gas atmosphere in a glove box.

[0082] The material of the dry coating mold is not particularly limited, but the dry coating mold may include plastic, aluminum, and stainless steel.

[0083] The transverse width of the dry application mold may be from 18 mm to 100 mm, and preferably, the transverse width of the dry application mold may be from 54 mm to 90 mm.

[0084] If the horizontal width of the dry coating mold exceeds 100 mm, there is a problem that the dry coating mold goes beyond the tray containing the rare earth diffusion powder (20) and the coating does not proceed effectively. If it is less than 18 mm, there is a problem that it is not suitable for the purpose of being used for large-capacity dry coating.

[0085] The vertical width of the dry application mold may be from 18 mm to 100 mm, and preferably, the vertical width of the dry application mold may be from 42 mm to 90 mm.

[0086] If the vertical width of the dry coating mold exceeds 100 mm, there is a problem that the dry coating mold goes beyond the tray containing the rare earth diffusion powder (20), and thus the coating does not proceed effectively. If it is less than 18 mm, there is a problem that it is not suitable for the purpose of being used for large-capacity dry coating.

[0087] The vertical thickness of the dry coating mold can be 2 mm to 4 mm. If the vertical thickness of the dry coating mold exceeds 4 mm, there is a problem that the number of magnets that can be applied decreases as the thickness increases. If it is less than 2 mm, there is a problem with the durability of the dry coating mold.

[0088] The width in the transverse direction of the area where at least one RE-Fe-B sintered magnet mother body (100) is placed within the dry coating mold may be 24 mm to 84 mm, and the width in the transverse direction is not limited thereto.

[0089] For example, when the RE-Fe-B sintered magnet matrix (100) has a size of 12 mm x 12 mm x 5 mm, 2 to 7 RE-Fe-B sintered magnet matrixes (100) can be arranged in the dry coating mold.

[0090] If the horizontal width of the area where at least one RE-Fe-B sintered magnet mother body (100) is placed within the dry coating mold exceeds 84 mm, there is a problem that the dry coating mold goes beyond the tray containing the rare earth diffusion powder (20), making the coating ineffective. If it is less than 24 mm, there is a problem that it is not suitable for the purpose of large-capacity coating.

[0091] In addition, the vertical width of the region in which at least one RE-Fe-B sintered magnet mother body (100) is placed within the dry coating mold may be 24 mm to 48 mm, and the width in the vertical direction is not limited thereto.

[0092] For example, when the RE-Fe-B sintered magnet matrix (100) has a size of 12 mm x 12 mm x 5 mm, two to four RE-Fe-B sintered magnet matrixes (100) can be placed in the dry coating mold.

[0093] If the vertical width of the area where at least one RE-Fe-B sintered magnet mother body (100) is placed within the dry coating mold exceeds 48 mm, there is a problem that the dry coating mold goes beyond the tray containing the rare earth diffusion powder (20), making the coating ineffective. If it is less than 24 mm, there is a problem that it is not suitable for the purpose of large-capacity coating.

[0094] For example, if the horizontal width of the area where at least one RE-Fe-B-based sintered magnet mother body (100) is arranged in the dry coating mold is 84 mm, the vertical width is 48 mm, and the RE-Fe-B-based sintered magnet mother bodies (100) have a size of 12 mm x 12 mm x 5 mm, a total of 28 RE-Fe-B-based sintered magnet mother bodies (100) can be arranged in the dry coating mold, and in this case, since the RE-Fe-B-based sintered magnet mother bodies (100) can be tightly fixed in the dry coating mold, a large amount of rare earth diffusion powder (20) can be effectively applied.

[0095] The dry coating mold is not particularly limited and can be adjusted according to the RE-Fe-B sintered magnet matrix (100). For example, the dry coating mold can be manufactured in a square shape.

[0096] Therefore, the method for manufacturing a RE-Fe-B sintered magnet (130) using dry coating according to one embodiment of the present invention applies a stamping method of stamping a binder (10) and a rare earth diffusion powder (20) like a stamp on the first surface of a RE-Fe-B sintered magnet mother body (100) using a dry coating method, and suppresses side coating of magnets, thereby improving the magnetic properties of the RE-Fe-B sintered magnet (130).

[0097] The RE-Fe-B sintered magnet (130) may include RE-Fe-B (RE includes at least one of Nd, Pr, La, Ce, Y, Gd, Ho, Dy, and Tb) magnet powder.

[0098] At this time, RE may include neodymium (Nd), and may further include at least one of praseodymium (Pr), lanthanum (La), cerium (Ce), yttrium (Y), gadolinium (Gd), holmium (Ho), dysprosium (Dy), and terbium (Tb), and preferably, the RE-Fe-B sintered magnet (130) may be Nd-Ce-Fe-B.

[0099] For example, RE-Fe-B sintered magnet (130) is (Nd,Ce)2Fe 14 It can be B, and at this time, the weight ratio can be 25 wt% PrNd, 7 wt% Ce, 0.94 wt% Fe bal.

[0100] In step S110, the RE-Fe-B sintered magnet mother body (100) can have a binder (10) applied to the first surface.

[0101] At this time, the first surface means the upper or lower surface of the RE-Fe-B system sintered magnet mother body (100), and a binder (10) can be applied to the upper or lower surface of the RE-Fe-B system sintered magnet mother body (100).

[0102] Specifically, the binder (10) can be applied to the upper or lower surface of the RE-Fe-B sintered magnet mother body (100) to form an adhesive layer to which the rare earth diffusion powder (20) is attached.

[0103] The binder (10) may be either polyvinyl alcohol (PVA) or polyvinyl chloride (PVC), and preferably, the binder (10) may be polyvinyl alcohol (PVA).

[0104] At this time, polyvinyl alcohol (PVA) used as a binder (10) is in the form of a liquid glue, and can be applied to the upper or lower surface of the RE-Fe-B sintered magnet mother body (100).

[0105] For example, polyvinyl alcohol (PVA) can be applied to the upper surface of a RE-Fe-B sintered magnet mother body (100) using a cotton swab, and rare earth diffusion powder (20) can be attached onto the polyvinyl alcohol (PVA).

[0106] In addition, the RE-Fe-B sintered magnet mother body (100) can be turned over and polyvinyl alcohol (PVA) can be applied once more to the lower surface of the RE-Fe-B sintered magnet mother body (100), and rare earth diffusion powder (20) can be attached on the polyvinyl alcohol (PVA), and can be applied a total of two times.

[0107] The thickness of the applied binder (10) layer may be 10 µm to 50 µm. If the thickness of the applied binder (10) layer is less than 10 µm, there is a problem of non-adhesion when applying the powder, and if it exceeds 50 µm, there is a problem of the liquid binder clumping together with the diffusion source due to excessive application of the binder (10).

[0108] In step S110, a RE-Fe-B sintered magnet mother body (100) may be formed by applying a binder (10) to the first surface of the RE-Fe-B sintered magnet mother body (100), and attaching a rare earth diffusion powder (20) onto the applied binder (10).

[0109] Rare earth diffusion powder (20) is TbH x and DyH x (x is the number of atoms, 1≤x≤3) It can be any one of them, preferably TbH.

[0110] By using rare earth hydride containing heavy rare earth elements such as Dy and Tb as rare earth diffusion powder (20), the coercivity of RE-Fe-B system sintered magnet (130) can be improved due to increased magnetic anisotropy.

[0111] The rare earth diffusion powder (20) can be manufactured in the form of a ribbon alloy, and after hydrogen disproportionation treatment, it can be manufactured by grinding using any one of a ball mill, a jet mill, a basket mill, and grinding, and preferably, a basket mill method can be used.

[0112] In detail, the raw material of rare earth diffusion powder (20) is manufactured into an alloy form using induction melting, and the alloy is manufactured into a thin ribbon form through a melt spinning process.

[0113] After this, the first crushing is performed through hydrogen disproportionation treatment, and then the second grinding is performed under an argon (Ar) atmosphere in a glove box to produce an alloy powder of 53㎛ or less, and the third crushing is performed through a basket mill for the final crushing to refine the powder.

[0114] At this time, by separating the solvent and solute from the thirdly pulverized powder and drying the powder, a dry powder, which is a rare earth diffusion powder (20), can be obtained.

[0115] The basket mill method can be performed under any one of the gas atmospheres of argon (Ar), nitrogen (N), hydrogen (H2), and vacuum.

[0116] At this time, the basket mill method manufactures rare earth diffusion powder (20) by using high energy generated from frictional force due to rotation, and at this time, the basket mill method is performed under a gas atmosphere of any one of inert gases such as argon (Ar), nitrogen (N), hydrogen (H2), and vacuum, thereby preventing oxidation of the rare earth alloy and reducing the size of the powder as much as possible to reduce the melting point.

[0117] The size of the rare earth diffusion powder (20) can be 30 ㎛ to 53 ㎛, and if the size of the rare earth diffusion powder (20) exceeds 53 ㎛, there is a problem of uneven application due to the large size of the powders.

[0118] As the size of the rare earth diffusion powder (20) decreases, the degree of uniform dispersion in the RE-Fe-B system sintered magnet matrix (100) increases, so that the diffusion source can be uniformly coated during dry coating, thereby securing improved magnetic properties.

[0119] The thickness of the attached rare earth diffusion powder layer can be 80 ㎛ to 150 ㎛. If the thickness of the attached rare earth diffusion powder layer is less than 80 ㎛, there is a problem that the magnetic properties do not increase significantly, and if it exceeds 150 ㎛, there is a problem that the magnet is corroded due to over-coating.

[0120] The conventional dipping coating method produces rare earth diffusion powder through grinding and produces slurry through precipitation, which causes oxidation problems using the slurry, and causes waste of slurry due to the use of excessive slurry for dipping coating.

[0121] Therefore, the method for manufacturing a RE-Fe-B sintered magnet (130) using dry coating according to one embodiment of the present invention can solve the problem of conventional slurry waste and the problem of oxidation caused by slurry manufacturing by directly attaching rare earth diffusion powder (20) to the magnet surface using the dry coating method.

[0122] Next, a method for manufacturing a RE-Fe-B sintered magnet (130) using dry coating according to one embodiment of the present invention includes a step (S120) of applying a binder (10) to a second surface of a RE-Fe-B sintered magnet (110) including a first attachment surface and attaching rare earth diffusion powder (20).

[0123] In step S120, the RE-Fe-B sintered magnet (110) including the first attachment surface can apply a binder (10) to the second surface.

[0124] At this time, the second surface means the upper or lower surface positioned facing the first attachment surface of the RE-Fe-B sintered magnet (110) including the first attachment surface, and a binder (10) can be applied to the upper or lower surface of the RE-Fe-B sintered magnet (110) including the first attachment surface.

[0125] Specifically, the binder (10) can be applied to the upper or lower surface of the RE-Fe-B sintered magnet (110) including the first attachment surface to form an adhesive layer to which the rare earth diffusion powder (20) is attached.

[0126] Hereinafter, step S120 is performed in the same manner as step S110, and a description of the same method is omitted.

[0127] Lastly, the method for manufacturing a RE-Fe-B sintered magnet (130) using dry coating according to one embodiment of the present invention includes a step (S130) of heat-treating a RE-Fe-B sintered magnet (120) including first and second attachment surfaces to diffuse rare earth diffusion powder (20) into the interior.

[0128] Step S130 may include a first heat treatment step performed at a heat treatment temperature of 800°C to 1000°C. If the heat treatment temperature is lower than 800°C, there is a problem that diffusion does not occur properly because it is lower than the melting point of the rare earth diffusion powder (20), and if it exceeds 1000°C, there may be a problem that magnetic properties are reduced due to abnormal grain growth and columnar decomposition.

[0129] The first heat treatment step can be performed to homogeneously diffuse the rare earth diffusion powder (20) inside the RE-Fe-B sintered magnet (120) including the first and second attachment surfaces.

[0130] In addition, the first diffusion heat treatment time in step S130 may be 2 to 6 hours, and if the heat treatment time is less than 2 hours, there may be a problem that diffusion does not occur properly due to insufficient diffusion time of the rare earth diffusion powder (20), and if it exceeds 6 hours, there may be a problem that grain boundary diffusion of the rare earth diffusion powder (20) does not occur properly.

[0131] Step S130 may include a second heat treatment step performed at a heat treatment temperature of 400°C to 600°C. If the heat treatment temperature is less than 400°C, there may be a problem that microstructure improvement is not properly performed, and if it exceeds 600°C, there may be a problem that grain growth is caused.

[0132] Additionally, the second diffusion heat treatment time in step S130 may be 2 to 6 hours.

[0133] The second heat treatment step is performed at a relatively lower temperature than the first heat treatment step after performing the first heat treatment step, and can be performed to improve the microstructure of the RE-Fe-B sintered magnet (130).

[0134] In particular, when performing the first heat treatment step and the second heat treatment step, since the temperature condition has a greater influence on the diffusion of the rare earth diffusion powder (20) than the time condition, the process conditions are optimized in the order of temperature and time.

[0135] Therefore, a RE-Fe-B sintered magnet (130) according to an embodiment of the present invention can be manufactured through a method for manufacturing a RE-Fe-B sintered magnet (130) using dry coating according to an embodiment of the present invention.

[0136] The RE-Fe-B sintered magnet (130) of the present invention includes a rare earth alloy phase in which rare earth diffusion powder (20) is diffused into the internal grain boundaries of a RE-Fe-B base material (RE includes at least one of Nd, Pr, La, Ce, Y, Gd, Ho, Dy, and Tb) through grain boundary diffusion treatment, and the rare earth alloy phase can be represented by the following chemical formula 1.

[0137] [Chemical Formula 1]

[0138] (HR)2Fe 14 B

[0139] (In Chemical Formula 1, HR includes at least one of Dy and Tb)

[0140] Therefore, according to one embodiment of the present invention, a grain boundary diffusion process (GBDP) can be performed by attaching rare earth diffusion powder through a relatively simple process, and by attaching rare earth diffusion powder to the upper and lower surfaces of a magnet using a dry application method of a stamping method in the form of a stamp, the rare earth diffusion powder can be effectively suppressed from being applied to the side surfaces of the magnet, thereby improving magnetic properties.

[0141] In particular, since a large quantity of rare earth diffusion powder can be uniformly attached by performing dry coating using a stamping method using a dry coating mold, a large quantity of RE-Fe-B sintered magnets can be manufactured at one time.

[0142] In addition, by applying a binder to a surface and directly attaching a rare earth diffusion powder on the applied binder, improved magnetic properties can be secured compared to a relatively small amount of application, and a method for manufacturing a RE-Fe-B sintered magnet using dry application that can solve the problems of slurry waste and oxidation, which are problems of the existing dipping application method, and an RE-Fe-B sintered magnet manufactured thereby can be provided.

[0143]

[0144] Hereinafter, the present invention will be described in more detail through examples. These examples are intended to explain the present invention more specifically, but the scope of the present invention is not limited by these examples.

[0145]

[0146] Comparative Example 1: Dipping application

[0147] TbHx powder with a size of less than 30㎛ was mixed with 200 g ethanol in a ratio of 200 g: 1500 ml, and then ground and mixed using basket milling at 850 rpm for approximately 3 hours. After basket milling, the solution was aged for approximately 3 days to adjust the concentration and remove residual hydrogen in the powder, and then the ethanol was removed to adjust the concentration of the solution. After adjusting the concentration to approximately 1 wt%, dipping application was performed.

[0148]

[0149] Comparative Example 2: Dipping application after side taping

[0150] The side surface, which is the plane parallel to the c-axis of the prepared Nd-Fe-B magnet, was taped using Kapton tape. Afterwards, dipping application was performed in the same manner as in Comparative Example 1, and the Kapton tape attached to the side surface was removed and heat treatment was performed.

[0151]

[0152] Example 1: Dry application

[0153] TbHx powder having a size of less than 30 μm was prepared, and 10 to 50 μm of PVA binder was applied to the prepared NdCeFeB sintered magnet matrix using a dry coating mold, and the prepared TbH rare earth diffusion powder was attached using a stamping method to a thickness of 80 to 150 μm.

[0154] Next, the GBDP process was performed to diffuse TbHx within the NdCeFeB sintered magnet matrix. After being placed in a furnace, heat treatment was performed at 850°C for 6 hours to diffuse Tb and then cooled to room temperature. After that, to improve the microstructure, heat treatment was performed at 450°C for 3 hours and then cooled to room temperature.

[0155]

[0156] Example 2: Dry application after basket milling

[0157] 200 g of TbHx rare earth diffusion powder and 1500 ml of ethanol were mixed and basket milled. Basket milling was performed under the same conditions as Comparative Example 1. Through basket milling, the powder was pulverized to an average particle size of less than 30 μm, and then the slurry was allowed to settle for 3 days to separate the solvent and solute. After removing the solvent, the powder was dried, and a PVA binder was applied to the prepared NdCeFeB sintered magnet matrix at a thickness of 10 μm to 50 μm using a dry coating mold, and the prepared TbH rare earth diffusion powder was attached using a stamping method at a thickness of 80 to 150 μm.

[0158] Next, the GBDP process was performed to diffuse TbHx within the NdCeFeB sintered magnet matrix. After being placed in a furnace, heat treatment was performed at 850°C for 6 hours to diffuse Tb and then cooled to room temperature. After that, to improve the microstructure, heat treatment was performed at 450°C for 3 hours and then cooled to room temperature.

[0159]

[0160] Fig. 6 is a schematic diagram illustrating Comparative Example 1 and Example 1, and Fig. 7 is an image of a RE-Fe-B system sintered magnet according to Comparative Example 1 and Example 1.

[0161] Referring to FIGS. 6 and 7, it can be confirmed that in Comparative Example 1 (dipping coating), rare earth diffusion powder is applied to all surfaces of the upper surface, lower surface, and side surfaces of the RE-Fe-B system sintered magnet, and in Example 1 (dry coating), it can be confirmed that rare earth diffusion powder is applied only to the upper surface and lower surface of the RE-Fe-B system sintered magnet.

[0162] Accordingly, in Example 1 (dry coating), rare earth diffusion powder is applied only to the upper and lower surfaces of the RE-Fe-B sintered magnet, thereby suppressing lateral diffusion of the rare earth diffusion powder.

[0163]

[0164] Figure 8a shows the intrinsic coercivity (H) of RE-Fe-B sintered magnets according to comparative example 1 and example 1. cj ) is a graph showing the residual flux density (B r ) is a graph showing the maximum energy ((BH) max )) is a graph showing the

[0165] Referring to Figures 8a to 8c, Example 1 (dry application) has an intrinsic coercivity (Hcj) of 16.95 kOe and a maximum energy ((BH) max )) It can be confirmed that this is improved compared to Comparative Example 1 (dipping application) with 27.255MGOe, and the residual flux density (B r ) is 12.81 kG, which is similar to Comparative Example 1 (dipping application).

[0166] In general, the residual flux density (Br) and the maximum magnetic energy product (BH) max )) is a trade-off relationship with the intrinsic coercivity (Hcj), and as the intrinsic coercivity (Hcj) of dry coating increases, the residual flux density (Br) and maximum magnetic energy product ((BH) max )) shows a decreasing trend.

[0167] In addition, for RE-Fe-B sintered magnets, which are generally applied to the drive motors of eco-friendly vehicles, an increase in intrinsic coercivity (Hcj) is important, and in order to significantly improve the intrinsic coercivity (Hcj) value of Example 1 (dry application), a certain degree of residual flux density (Br) and maximum magnetic energy product ((BH) max )) may follow.

[0168]

[0169] The following Figures 9a to 9f and Figures 10a to 10f show Comparative Example 1 (dipping application) and Example 1 (dry application) in detail according to the amount applied. Comparative Example 1 was performed as Comparative Example 1-1 in which dipping application was performed at 1.01 wt% and Comparative Example 1-2 in which dipping application was performed at 1.04 wt%, and Example 1 was performed as Example 1-1 in which dry application was performed at 1.20 wt%, Example 1-2 in which dry application was performed at 1.01 wt%, and Example 1-3 in which dry application was performed at 1.05 wt%.

[0170] Figure 9a shows the intrinsic coercivity (H) of RE-Fe-B system sintered magnets according to Comparative Example 1-1, Comparative Example 1-2, Example 1-1, Example 1-2, and Example 1-3. cj ) is a graph showing the residual flux density (B r ) is a graph showing the maximum energy ((BH) max )) is a graph showing the

[0171] Figure 9d shows the coercivity (H) of RE-Fe-B system sintered magnets according to Comparative Example 1-1, Comparative Example 1-2, Example 1-1, Example 1-2, and Example 1-3. cb ) is a graph illustrating the magnetic field (H k ) is a graph showing the aspect ratio (H k / H cj ) is a graph showing the

[0172] Referring to Figures 9a to 9f, Example 1-2 (dry application 1.20 wt%) has an intrinsic coercivity (H cj), residual flux density (B r ), maximum energy ((BH) max )), coercive force (H cb ), magnetic field (H k ) and aspect ratio (H k / H cj ) It can be confirmed that the numerical value has improved compared to Comparative Example 1-1 (dipping application 1.01 wt%) and Comparative Example 1-2 (dipping application 1.04 wt%).

[0173] Fig. 10a is a graph showing the magnetization curve of a basic magnet, Fig. 10b is a graph showing the magnetization curve of Comparative Example 1-1, and Fig. 10c is a graph showing the magnetization curve of Comparative Example 1-2.

[0174] FIG. 10d is a graph showing a magnetization curve of Example 1-1, FIG. 10e is a graph showing a magnetization curve of Example 1-2, and FIG. 10f is a graph showing a magnetization curve of Example 1-3.

[0175] Figures 10g and 10h are graphs showing the magnetization curve of a blank magnet.

[0176] Referring to FIGS. 10g and 10h, in general, when performing a grain boundary diffusion process (GBDP) of a Nd-Fe-B magnet, a diffusion source is applied to the base magnet and heat-treated. Since the magnetic properties of the base magnet are increased by the heat treatment alone, the performance values ​​of a blank magnet that was heat-treated without applying a diffusion source were checked to confirm that the magnetic properties are improved only by the diffusion source.

[0177] Accordingly, referring to FIGS. 10a to 10h, it can be confirmed that the magnetic properties of the magnets according to Examples 1-1, 1-2, and 1-3 were improved through dry application rather than through heat treatment alone.

[0178]

[0179] Figure 11 is an image illustrating the properties of the RE-Fe-B sintered magnet used in Figures 7 to 10h.

[0180] Referring to Fig. 11, it can be confirmed that the overall BH properties of Example 1 (dry application) are superior to those of Comparative Example 1 (dipping application).

[0181]

[0182] The following Figures 12 to 14 and Figures 15a to 15c were each performed twice for accurate measurements of Comparative Example 2 (dipping application after side taping) and Example 2 (dry application after basket milling). Comparative Example 2 was performed as Comparative Example 2-1 and Comparative Example 2-2, and Example 2 was performed as Example 2-1 and Example 2-2.

[0183] Fig. 12 is a schematic diagram illustrating Comparative Example 2, Fig. 13 is an image of a RE-Fe-B sintered magnet according to Comparative Example 2, and Fig. 14 is an image of a RE-Fe-B sintered magnet according to Comparative Example 2 and Example 2.

[0184] Referring to FIGS. 12 and 14, Comparative Example 1 (dipping application) was supplemented by attaching tape to the side of Comparative Example 2 (dipping application after side taping) and then applying dipping application. Through this, it can be confirmed that in Comparative Example 2 (dipping application after side taping) and Example 2 (dry application after basket milling), rare earth diffusion powder was applied only to the upper and lower surfaces of the RE-Fe-B system sintered magnet.

[0185]

[0186] Figure 15a shows the intrinsic coercivity (H) of RE-Fe-B sintered magnets according to comparative example 2 and example 2. cj ) is a graph showing the residual flux density (B r ) is a graph showing the maximum energy ((BH) max )) is a graph showing the

[0187] Referring to Figures 15a to 15c, Example 2 (dry application after basket milling) has an intrinsic coercive force of 18.75 kOe and a residual flux density (B r ) was 12.975 kG, which was improved compared to Comparative Example 2 (dipping application after side taping), and the maximum energy ((BH) max )) It can be confirmed that this is similar to Comparative Example 2 (dipping application after side taping) with 32.83MGOe.

[0188] Accordingly, referring to FIGS. 15a to 15c, in order to significantly improve the intrinsic coercivity (Hcj) value of Example 2 (dry application after basket milling), a certain degree of residual flux density (Br) and maximum magnetic energy product ((BH) max )) may follow.

[0189]

[0190] Fig. 16 is an image illustrating the properties of the RE-Fe-B sintered magnet used in Figs. 13 to 15c.

[0191] Therefore, referring to FIGS. 15a to 16, the intrinsic coercivity (H) in Comparative Example 2 and Example 2 cj ), residual flux density (B r ) and maximum energy ((BH) max )) Since the difference is not large, the method for manufacturing a RE-Fe-B system sintered magnet using dry coating according to one embodiment of the present invention, which attaches the diffusion powder using a relatively simple process using a dry coating method of stamping the rare earth diffusion powder like a stamp, can shorten the manufacturing process time and improve efficiency.

[0192]

[0193] Although the present invention has been described with reference to limited embodiments and drawings, it is not limited to the embodiments described above, and those skilled in the art will appreciate that various modifications and variations may be made based on this description. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the following claims but also by equivalents thereof.

Claims

1. A step of applying a binder to the first surface of a RE-Fe-B sintered magnet and attaching rare earth diffusion powder; A step of applying a binder to the second surface of the RE-Fe-B sintered magnet and attaching rare earth diffusion powder; and A step of heat-treating the RE-Fe-B sintered magnet to diffuse the rare earth diffusion powder into the interior of the RE-Fe-B sintered magnet; Including, A method for manufacturing a RE-Fe-B sintered magnet using dry coating, characterized in that the RE-Fe-B sintered magnet uses dry coating to attach the binder and the rare earth diffusion powder.

2. In paragraph 1, A method for manufacturing a RE-Fe-B sintered magnet using dry coating, characterized in that the above dry coating is one of stamping, vacuum deposition, ion plating, and sputtering.

3. In paragraph 2, A method for manufacturing a RE-Fe-B sintered magnet using dry coating, characterized in that the above stamping method uses a dry coating mold.

4. In paragraph 2, A method for manufacturing a RE-Fe-B system sintered magnet using dry coating, characterized in that the rare earth diffusion powder is controlled to be applied to the side of the RE-Fe-B system sintered magnet by the stamping method.

5. In paragraph 1, A method for manufacturing a RE-Fe-B sintered magnet using dry coating, characterized in that the binder is one of polyvinyl alcohol (PVA) and polyvinyl chloride (PVC).

6. In paragraph 1, A method for manufacturing a RE-Fe-B system sintered magnet using dry coating, characterized in that the thickness of the binder is 10㎛ to 50㎛.

7. In paragraph 1, The above rare earth diffusion powder is TbH x and DyH x (x is the number of atoms, 1≤x≤3) A method for manufacturing a RE-Fe-B system sintered magnet using dry coating characterized by one of the following.

8. In paragraph 1, A method for manufacturing a RE-Fe-B system sintered magnet using dry coating, characterized in that the size of the rare earth diffusion powder is 30 ㎛ to 53 ㎛.

9. In paragraph 1, A method for manufacturing a RE-Fe-B system sintered magnet using dry coating, characterized in that the thickness of the rare earth diffusion powder is 80 ㎛ to 150 ㎛.

10. In paragraph 1, The step of heat-treating the RE-Fe-B sintered magnet to diffuse the rare earth diffusion powder into the interior of the RE-Fe-B sintered magnet is as follows: A first heat treatment step performed at a heat treatment temperature of 800°C to 1000°C; and A second heat treatment step performed at a heat treatment temperature of 400°C to 600°C; A method for manufacturing a RE-Fe-B system sintered magnet using dry coating, characterized in that it includes.

11. In paragraph 10, The above first heat treatment time is 2 to 6 hours, A method for manufacturing a RE-Fe-B sintered magnet using dry coating, characterized in that the second heat treatment time is 2 to 6 hours.

12. A RE-Fe-B sintered magnet characterized by being manufactured according to Article 1.

13. In paragraph 12, The above RE-Fe-B sintered magnet includes a rare earth alloy phase in which rare earth diffusion powder is diffused into the internal grain boundaries of a RE-Fe-B substrate (wherein RE includes at least one of Nd, Pr, La, Ce, Y, Gd, Ho, Dy, and Tb) through grain boundary diffusion treatment. A RE-Fe-B type sintered magnet characterized in that the rare earth alloy phase is represented by the following chemical formula 1. [Chemical Formula 1] (HR)2Fe 14 B (In the above chemical formula 1, the HR includes at least one of Dy and Tb)

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