Method for manufacturing re-fe-b-based grain boundary diffusion magnet using slurry prepared through hydrogen atmosphere heat treatment of multi-component alloy, and grain boundary diffusion magnet manufactured thereby
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-03-07
- Publication Date
- 2026-08-13
Smart Images
Figure KR2025099614_13082026_PF_FP_ABST
Abstract
Description
Method for manufacturing RE-FE-B grain boundary diffusion magnets using a slurry produced by heat treatment of a multicomponent alloy in a hydrogen atmosphere, and grain boundary diffusion magnets manufactured thereby
[0001] The present invention relates to a method for manufacturing an RE-Fe-B grain boundary diffusion magnet using a slurry produced by heat treatment of a multicomponent alloy in a hydrogen atmosphere, and to a grain boundary diffusion magnet manufactured thereby. More specifically, the invention relates to a process of manufacturing a multicomponent alloy with a low melting point into a slurry form to facilitate grain boundary diffusion in order to reduce the amount of heavy rare earth elements used compared to existing grain boundary diffusion sources, a method for manufacturing a Ce-substituted RE-Fe-B grain boundary diffusion magnet having magnetic properties of 90% or more by applying the same, and to a grain boundary diffusion magnet manufactured thereby.
[0002] Nd-Fe-B sintered magnets are rare-earth magnets composed mainly of neodymium (Nd), iron (Fe), and boron (B). They possess excellent magnetic properties and are utilized in various industries requiring high-performance magnets. In particular, demand for them is expanding for motor applications, and consequently, there is a requirement for them to possess even higher coercivity.
[0003] Accordingly, a grain boundary diffusion process is performed on rare earth magnets to improve their magnetic properties. Grain boundary diffusion is a process that improves the magnetic properties of a magnet by applying a specific element, primarily a rare earth metal, to the surface of the magnet and then diffusing it into the grain boundaries within the magnet through heat treatment.
[0004] Conventional technology utilized fluorides, hydrides, or metals containing heavy rare earths to facilitate grain boundary diffusion of heavy rare earths such as Tb and Dy. However, due to the limited resources and cost associated with heavy rare earths, there was a need for resources to minimize or replace them. To address this, methods involving the addition of transition metals such as Al, Cu, Co, and Ga, or other materials, to heavy rare earths, or the use of only light rare earths, were employed.
[0005] As described above, the method of adding transition metals to heavy rare earths has the advantage of lowering the melting point and increasing wettability compared to using only heavy rare earths, thereby increasing grain boundary diffusion efficiency. However, it has the disadvantage that it is difficult to control uniform coating and diffusion amount during the process of coating the alloy onto sintered magnets, and it is difficult to apply to mass production. The present invention was devised to solve these problems.
[0006] Meanwhile, the present invention is a technology developed through the Next Generation Promising Seed Technology Convergence Fast Track Research Project (2710001933 / 00238493) "Development of High-Efficiency Permanent Magnet Motors for Micro / Personal-E-Mobility" of the Ministry of Science and ICT of the Republic of Korea and the National Research Foundation of Korea from January 1, 2024 to March 3, 2025.
[0007] The objective of the present invention is to solve the aforementioned conventional problems and to provide a method for manufacturing an RE-Fe-B grain boundary diffusion magnet using a slurry produced by hydrogen atmosphere heat treatment of a multicomponent alloy, which can significantly reduce the amount of heavy rare earth elements used compared to existing grain boundary diffusion sources, while increasing the uniformity of the grain boundary diffusion source coating, making it easy to control the amount of diffusion, and obtaining high magnetic properties of more than 90% compared to existing methods, and a grain boundary diffusion magnet manufactured thereby.
[0008] The above objective is achieved by a method for manufacturing an RE-Fe-B grain boundary diffusion magnet using a slurry produced through hydrogen atmosphere heat treatment of a multicomponent alloy, comprising, according to the present invention: an alloy manufacturing step for manufacturing a rare earth alloy; a hydrogen atmosphere heat treatment step for heat-treating the manufactured rare earth alloy in a hydrogen atmosphere; a step for grinding the rare earth alloy to produce a ground material; a basket milling step for producing a finely ground mixture by applying a basket milling process to the ground material; an immersion step for immersing the mixture to produce a slurry; a diffusion step for applying the slurry to the surface of a sintered magnet and heat-treating it; and a residue removal step for removing residue from the surface of the sintered magnet after the diffusion step, wherein the rare earth alloy comprises heavy rare earth elements, light rare earth elements, and metal elements.
[0009] In addition, the above sintered magnet may be an Nd-Ce-Fe-B sintered magnet.
[0010] In addition, the above rare earth alloy is HRE 10 -LRE 60 -TM 30 It can be manufactured with at% (where HRE is a heavy rare earth element, LRE is a light rare earth element, and TM is a metallic element).
[0011] In addition, the heavy rare earth element may include Tb, the light rare earth element may include Pr and La, and the metal element may include Cu and Ga.
[0012] In addition, the hydrogen atmosphere heat treatment step is 9.00x10 -6 It can be heat-treated at 200 to 400°C for 4 to 12 hours by injecting hydrogen gas in a high vacuum of less than Torr.
[0013] In addition, the basket milling step can finely grind the above-mentioned ground material by mixing it with ethyl alcohol through a basket milling process and milling it at a speed of 600-1800 rpm for 3 to 6 hours.
[0014] In addition, the above immersion step can be prepared in the form of a slurry by immersing the mixture at room temperature for 1 to 3 days.
[0015] The above objective is achieved by an RE-Fe-B grain boundary diffusion magnet utilizing a slurry produced through hydrogen atmosphere heat treatment of a multicomponent alloy, characterized in that, according to the present invention, a mixed material including heavy rare earth elements, light rare earth elements, and metal elements is diffused at the grain boundaries by applying a rare earth alloy in the form of a slurry to the surface and heat-treating it.
[0016] The above objective is achieved by an electronic device comprising an RE-Fe-B grain boundary diffusion magnet utilizing a slurry produced by heat treatment of a multi-component alloy in a hydrogen atmosphere according to the present invention.
[0017] According to the present invention, by significantly reducing the amount of heavy rare earth elements used compared to conventional grain boundary diffusion sources to lower the manufacturing cost of grain boundary diffusion sintered magnets, and by applying a grain boundary diffusion source in the form of a slurry applicable to mass production processes, the uniformity of the application is improved and the amount of diffusion is controlled, thereby having the effect of securing magnetic properties of Ce substitution type sintered magnets of more than 90% compared to conventional methods.
[0018] Meanwhile, the effects of the present invention are not limited to those mentioned above, and various effects may be included within the scope obvious to a person skilled in the art from the contents described below.
[0019] FIG. 1 illustrates a flowchart of a method for manufacturing an RE-Fe-B grain boundary diffusion magnet using a slurry produced by heat treatment of a multicomponent alloy in a hydrogen atmosphere according to one embodiment of the present invention.
[0020] FIG. 2 illustrates the slurry manufacturing process of the manufacturing method of FIG. 1, and
[0021] FIG. 3 illustrates the process of applying the slurry of FIG. 2 to the surface of a sintered magnet, and
[0022] Figure 4 shows the results of measuring the coercivity and residual magnetic flux density of magnets manufactured by Examples 1 to 5, Comparative Example 1, and Comparative Example 2, respectively, which are embodiments of the present invention.
[0023] Hereinafter, some embodiments of the present invention will be described in detail with reference to the exemplary drawings. It should be noted that in assigning reference numerals to the components of each drawing, the same components are given the same reference numeral whenever possible, even if they are shown in different drawings.
[0024] In addition, when describing embodiments of the present invention, if it is determined that a detailed description of related known configurations or functions would hinder understanding of the embodiments of the present invention, such detailed description is omitted.
[0025] In addition, terms such as first, second, A, B, (a), (b), etc., may be used when describing the components of the embodiments of the present invention. These terms are used merely to distinguish the components from other components, and the essence, order, or sequence of the components is not limited by these terms.
[0026]
[0027] Now, with reference to the attached drawings, a method (S100) for manufacturing an RE-Fe-B grain boundary diffusion magnet using a slurry produced by hydrogen atmosphere heat treatment of a multi-component alloy according to an embodiment of the present invention will be described in detail.
[0028] FIG. 1 is a flowchart of a method (S100) for manufacturing an RE-Fe-B grain boundary diffusion magnet using a slurry produced by heat treatment of a multi-component alloy in a hydrogen atmosphere according to one embodiment of the present invention, FIG. 2 is a process for manufacturing the slurry of the manufacturing method (S100) of FIG. 1, FIG. 3 is a process for applying the slurry of FIG. 2 to the surface of a sintered magnet, FIG. 4 is a result of measuring the coercivity and residual magnetic flux density of magnets manufactured by Examples 1 to 5, Comparative Example 1, and Comparative Example 2, respectively, which are embodiments of the present invention.
[0029] As illustrated in FIG. 1, a method for manufacturing an RE-Fe-B grain boundary diffusion magnet using a slurry produced by heat treatment of a multi-component alloy in a hydrogen atmosphere according to one embodiment of the present invention (hereinafter, grain boundary diffusion magnet manufacturing method) (S100) may include an alloy manufacturing step (S110), a hydrogen atmosphere heat treatment step (S120), a grinding step (S130), a basket milling step (S140), an immersion step (S150), a diffusion step (S160), and / or a residue removal step (S170).
[0030] Conventionally, heavy rare earth elements such as Tb and Dy were utilized through grain boundary diffusion. However, heavy rare earth elements presented issues regarding limited resources and costs. Consequently, to minimize the consumption of heavy rare earth elements or to replace them, methods were employed in which transition metals such as Al, Cu, Co, and Ga, or other materials, were added to the heavy rare earth elements, or only light rare earth elements were used. However, while adding a small amount of transition metal to heavy rare earth elements lowers the melting point and increases grain boundary wettability to improve grain boundary diffusion efficiency compared to using only heavy rare earth elements, this method has the disadvantage that it is difficult to control uniform coating and diffusion amount during the process of coating the alloy onto sintered magnets, making it difficult to apply to mass production. To solve these problems, the present invention utilizes a slurry prepared through hydrogenation heat treatment of a multicomponent alloy containing small amounts of heavy rare earth elements, light rare earth elements, and metal elements for grain boundary diffusion.
[0031] First, the alloy manufacturing step (S110) is a step for manufacturing a rare earth alloy.
[0032] Rare earth alloys can be manufactured to include rare earth elements and metal components. In this case, the rare earth alloy may be an RE-TM alloy, where RE is a rare earth element and TM is a metal element. The rare earth alloy is slurried through a series of processes described below, and the slurry of the rare earth alloy may be attached to a rare earth sintered magnet described below and diffused into the grain boundaries.
[0033] Specifically, rare earth alloys are HRE 10 -LRE 60 -TM 30 It is preferable to manufacture it with a composition of at%, wherein the HRE preferably contains Tb as a heavy rare earth element, the LRE preferably contains Pr and La as light rare earth elements, and the TM preferably contains Cu and Ga as metallic elements. The light rare earth elements Pr and La form a high anisotropic magnetic field and improve the microstructure, while the metallic elements Cu and Ga can improve the melting point and wettability of the rare earth alloy.
[0034] Next, the hydrogen atmosphere heat treatment step (S120) is a step of heat-treating the rare earth alloy produced through the alloy manufacturing step in a hydrogen atmosphere.
[0035] The rare earth alloy manufactured through the above alloy manufacturing steps is heat-treated in a hydrogen atmosphere and subsequently ground through a grinding step. At this time, the heat treatment is 9.00 x 10 -6 Hydrogen gas can be injected in a high vacuum of less than Torr and carried out at 200 to 400°C for 4 to 12 hours.
[0036] Next, the crushing step (S130) is a step of producing a crushed material by crushing the rare earth alloy that has undergone the hydrogen atmosphere heat treatment step (S120).
[0037] The alloy produced through the above hydrogen atmosphere heat treatment process can be easily crushed using a mortar and pestle or the like due to its brittleness.
[0038] Next, the basket milling step (S140) is a step of producing a finely ground mixture by applying a basket milling process to the ground material.
[0039] The above-mentioned ground material can be finely ground by mixing it with ethyl alcohol through a basket milling process and milling it at a speed of 600 to 1800 rpm for 3 to 6 hours.
[0040] Next, the immersion step (S150) is a step of immersing the mixture to produce it in the form of a slurry.
[0041] The mixture produced through the basket milling step (S140) above may undergo an immersion process at room temperature for 1 to 3 days. The mixture that has undergone the immersion step (S150) above becomes a final slurry form for coating the sintered magnet described later.
[0042] Next, the diffusion step (S160) is a step of applying the slurry to the surface of the sintered magnet and heat-treating it.
[0043] The RE-Fe-B sintered magnet used in the above diffusion step (S160) may be a Ce substitution type sintered magnet. Specifically, it may be a 12mm x 12mm x 5mm Nd-Ce-Fe-B sintered magnet whose surface is etched by ultrasonically cleaning it in a 2% solution of ethanol and silver nitrate for 20 seconds.
[0044] The sintered magnet coated with the above slurry is heat-treated under preset conditions, thereby causing grain boundary diffusion in which the alloy in the form of the slurry, which is a grain boundary diffusion source, penetrates into the interior of the magnet.
[0045] Specifically, the diffusion step (S160) includes a process in which the material is heated at a heating rate of 30°C in a high vacuum atmosphere and maintained at a temperature of 900°C for 10 hours to melt and diffuse into the interior of the magnet to carry out a penetration reaction, and after surface coating, a stress relief and stabilization process is carried out through continuous heat treatment at 900°C for 10 hours and at 480°C for 3 hours, thereby lowering the difficulty of the technology and improving thermal stability by performing heat treatment at a lower temperature for a shorter time compared to existing technology.
[0046] Next, the residue removal step (S170) is a step of removing residue from the surface of the sintered magnet after the diffusion step (S160).
[0047] The residue removal step is a step to finally complete the grain boundary diffusion magnet by removing the residual slurry remaining on the surface of the rare earth sintered magnet that has undergone the grain boundary diffusion process.
[0048] According to a method (S100) for manufacturing a grain boundary diffusion magnet according to an embodiment of the present invention, which includes an alloy manufacturing step (S110), a hydrogen atmosphere heat treatment step (S120), a grinding step (S130), a basket milling step (S140), an immersion step (S150), a diffusion step (S160), and / or a residue removal step (S170) as described above, the amount of heavy rare earth elements used is significantly reduced compared to conventional grain boundary diffusion sources, thereby lowering the manufacturing cost of grain boundary diffusion sintered magnets. Furthermore, by applying a grain boundary diffusion source in the form of a slurry that is applicable to mass production processes, the uniformity of the application is improved and the amount of diffusion is controlled, thereby ensuring magnetic properties of Ce substitution type sintered magnets of more than 90% compared to conventional methods.
[0049]
[0050] Furthermore, the grain boundary diffusion magnet manufactured according to the above-described manufacturing method (S100) can be utilized by being included in an electronic device, and the electronic device may be any one selected from the group consisting of a computer hard disk, magnetic resonance imaging (MRI), an electric motor, a home appliance compressor, a battery electrode, a wind turbine, a speaker, headphones, and a magnetic bearing.
[0051]
[0052] The operation and effects of the present invention will be explained in more detail below through specific embodiments. However, these are presented as examples of the invention and do not limit the scope of the invention in any way.
[0053]
[0054] <Examples 1 to 5> Preparation of RE-Fe-B-based Medium-Light Rare Earth Grain Boundary Diffusion Magnets
[0055] The heavy rare earth element HRE is Tb, the light rare earth element LRE is Pr and La, the metallic element TM is Cu and Ga, and the composition is HRE 10 -LRE 60 -TM 30 A rare earth alloy with at% was manufactured.
[0056] Subsequently, the above rare earth alloy is 9.00 x 10 -6 Hydrogen gas was injected in a high vacuum of less than Torr and heat-treated at 200–400°C for 4–12 hours.
[0057] Subsequently, the heat-treated rare earth alloy was crushed using a mortar and pestle, mixed with ethyl alcohol through a basket milling process, and milled at a speed of 600 to 1800 rpm for 3 to 6 hours to produce a finely ground mixture.
[0058] Afterwards, the above mixture was immersed at room temperature for 1 to 3 days to prepare it in the form of a slurry.
[0059] Subsequently, the above slurry was applied to the surface of a 12.5 mm x 12.5 mm x 5 mm Nd-Ce-Fe-B sintered magnet that had been etched by ultrasonically cleaning the surface in a 2% solution of ethanol and silver nitrate for 20 seconds. At this time, the application amount for Example 1 was 1.02 wt%, the application amount for Example 2 was 1.55 wt%, the application amount for Example 3 was 2.05 wt%, the application amount for Example 4 was 2.61 wt%, and the application amount for Example 5 was 3.17 wt%.
[0060] Afterwards, the above sintered magnet was heated at a heating rate of 30°C in a high vacuum atmosphere, maintained at 900°C for 10 hours, and then continuously maintained at 480°C for 3 hours to perform heat treatment.
[0061] Subsequently, after removing the diffusion layer residue remaining on the surface of the magnet that had undergone diffusion and heat treatment, magnetization was performed using a Magnetizer, and magnetic properties were measured using a BH loop tracer.
[0062]
[0063] <Experimental Example 1> Analysis of Changes in Magnetic Properties of RE-Fe-B Medium-Light Rare Earth Grain Boundary Diffusion Magnets
[0064] The change in magnetic properties was measured using a BH loop tracer for each of the magnets: Examples 1 to 5 (slurry coating), Comparative Example 1 (Original) which was not treated with grain boundary diffusion, and Comparative Example 2 (metal ribbon) which was treated with grain boundary diffusion by attaching an alloy of the same composition with a metal ribbon.
[0065] As shown in Figure 4, compared to Comparative Example 1, which was not treated with grain boundary diffusion, and Comparative Example 2, which was treated with grain boundary diffusion by attaching an alloy of the same composition with a metal ribbon, it was found that the magnets of Examples 1 to 5, which were treated with grain boundary diffusion using a slurry prepared through heat treatment in a hydrogen atmosphere as a grain boundary diffusion source, could achieve an improvement in coercivity of 90% or more.
[0066]
[0067] Although all components constituting an embodiment of the present invention have been described above as being combined or operating in combination, the present invention is not necessarily limited to such an embodiment. That is, within the scope of the purpose of the present invention, all components may be selectively combined in one or more ways to operate.
[0068] Furthermore, terms such as "include," "compose," or "have" as described above, unless specifically stated otherwise, mean that the relevant component may be inherent; therefore, they should be interpreted as allowing for the inclusion of additional components rather than excluding them. All terms, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains, unless otherwise defined. Commonly used terms, such as those defined in advance, should be interpreted in accordance with their meaning in the context of the relevant technology and, unless explicitly defined in the present invention, should not be interpreted in an ideal or overly formal sense.
[0069] Furthermore, the above description is merely an illustrative explanation of the technical concept of the present invention, and those skilled in the art to which the present invention pertains will be able to make various modifications and variations within the scope of the essential characteristics of the present invention.
[0070] Accordingly, the embodiments disclosed in this invention are intended to illustrate, not limit, the technical concept of the invention, and the scope of the technical concept of the invention is not limited by these embodiments. The scope of protection of this invention shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of this invention.
Claims
1. Alloy manufacturing step for manufacturing rare earth alloys; A hydrogen atmosphere heat treatment step of heat-treating the manufactured rare earth alloy in a hydrogen atmosphere; A step of producing a crushed material by crushing the above rare earth alloy; A basket milling step for producing a finely ground mixture by applying a basket milling process to the above-mentioned ground material; An immersion step of preparing the above mixture in the form of a slurry by immersing it; A diffusion step of applying the above slurry to the surface of a sintered magnet and heat-treating it; and The method includes a residue removal step for removing residue from the surface of the sintered magnet after the above diffusion step, The above rare earth alloy is, A method for manufacturing an RE-Fe-B grain boundary diffusion magnet using a slurry produced by hydrogen atmosphere heat treatment of a multicomponent alloy, characterized by containing heavy rare earth elements, light rare earth elements, and metallic elements.
2. In Claim 1, The above-mentioned sintered magnet is, A method for manufacturing an RE-Fe-B grain boundary diffusion magnet using a slurry produced by hydrogen atmosphere heat treatment of a multicomponent alloy, characterized in that it is an Nd-Ce-Fe-B sintered magnet.
3. In Claim 1, The above rare earth alloy is, HRE 10 -LRE 60 -TM 30 A method for manufacturing an RE-Fe-B grain boundary diffusion magnet using a slurry produced by hydrogen atmosphere heat treatment of a multicomponent alloy, characterized by being manufactured with at% (wherein HRE is a heavy rare earth element, LRE is a light rare earth element, and TM is a metal element).
4. In Claim 3, The above-mentioned heavy rare earth elements are, Includes Tb, The above-mentioned light rare earth elements are, Includes Pr and La, The above metal element is, A method for manufacturing an RE-Fe-B grain boundary diffusion magnet using a slurry produced by heat treatment in a hydrogen atmosphere of a multicomponent alloy characterized by containing Cu and Ga.
5. In Claim 1, The above hydrogen atmosphere heat treatment step is, 9.00x10 -6 A method for manufacturing an RE-Fe-B grain boundary diffusion magnet using a slurry produced by hydrogen atmosphere heat treatment of a multicomponent alloy, characterized by injecting hydrogen gas in a high vacuum of Torr or less and heat treating at 200 to 400°C for 4 to 12 hours.
6. In Claim 1, The basket milling step above is, A method for manufacturing an RE-Fe-B grain boundary diffusion magnet using a slurry produced by hydrogen atmosphere heat treatment of a multi-component alloy, characterized by finely grinding the above-mentioned ground material by mixing it with ethyl alcohol through a basket milling process and milling it at a speed of 600 to 1800 rpm for 3 to 6 hours.
7. In Claim 1, The above immersion step is, A method for manufacturing an RE-Fe-B grain boundary diffusion magnet using a slurry produced by hydrogen atmosphere heat treatment of a multicomponent alloy, characterized by immersing the above mixture in a slurry form at room temperature for 1 to 3 days.
8. RE-Fe-B grain boundary diffusion magnet utilizing a slurry produced by hydrogen atmosphere heat treatment of a multicomponent alloy, characterized by grain boundary diffusion of a mixed material including heavy rare earth elements, light rare earth elements, and metal elements by applying a rare earth alloy in slurry form to the surface and heat treating it.
9. An electronic device comprising an RE-Fe-B grain boundary diffusion magnet utilizing a slurry produced by heat treatment of a multicomponent alloy according to claim 8 in a hydrogen atmosphere.