Method for manufacturing rare earth-sintered magnet and sintered magnet manufactured thereby

Abstract

The present invention relates to a method for manufacturing a rare earth-sintered magnet and a sintered magnet manufactured thereby, the method comprising: a magnet powder preparation step of preparing a RL-Fe-B-based magnet powder containing a light rare earth element (RL) and a RH-Fe-B-based magnet powder containing a heavy rare earth element (RH) by reduction-diffusion; a step of mixing the RL-Fe-B-based magnet powder and the RH-Fe-B-based magnet powder to prepare a mixture powder; and a step of sintering the mixture powder to manufacture a sintered magnet, wherein the RL is Nd or Pr and the RH is Dy or Tb.

Description

Method for manufacturing rare earth sintered magnets and sintered magnets manufactured therefrom

[0001] The present invention relates to a method for manufacturing a rare earth sintered magnet and a sintered magnet manufactured therefrom.

[0002]

[0003] Rare earth NdFeB magnets are made of Nd2Fe, a compound of the rare earth elements neodymium (Nd), iron, and boron (B). 14 This is a permanent magnet with a composition of B, and has been used as a general-purpose permanent magnet for 30 years since its development in 1983. These rare earth NdFeB magnets are used in various fields such as electronic information, automobile industry, medical devices, energy, and transportation. In particular, in line with the recent trend toward lightweight and miniaturization, they are being used in products such as electronic information devices, home electronics, mobile phones, robot motors, wind power generators, small motors for automobiles, and drive motors.

[0004] The typical manufacturing process for rare earth NdFeB magnets involves melting the metal, followed by a multi-step grinding process to produce alloy powder. This process is then subjected to a magnetic press process, followed by additional processes such as sintering and cutting. These processes all require a grinding step, which is time-consuming and requires a complex manufacturing process, such as surface coating after grinding.

[0005] In addition, rare earth NdFeB magnets generally use heavy rare earth (Dy, Tb) grain boundary diffusion (GBDP; Grain Boundary Diffusion Process) to secure high coercivity and thermal stability, thereby securing performance such as improved coercivity. The limitation of this heavy rare earth grain boundary diffusion method is that it can generally be applied to rare earth sintered magnets with a uniform thickness of less than 7 mm due to the restriction of the grain boundary diffusion distance of the heavy rare earth material coated on the surface, and it is difficult to apply it to rare earth magnets in shapes other than plate shapes such as arc-type, ring-type, irregular shapes, and large sizes.

[0006] Accordingly, the need for research on high-coercivity rare earth sintered magnets with a simple manufacturing process for rare earth magnet powder and no restrictions on size and shape is increasing.

[0007]

[0008] The purpose of the present invention is to provide a method for manufacturing a high-coercivity rare earth sintered magnet that can be manufactured into various sizes and shapes by a simple process without going through additional process steps such as a grain boundary diffusion process, and a high-coercivity rare earth sintered magnet manufactured thereby.

[0009]

[0010] The problems to be solved by the present invention are not limited to the problem(s) mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0011]

[0012] In order to achieve the above purpose, the present invention provides a method for producing rare earth elements (R) by a reduction-diffusion method. L ) including R L -Fe-B magnetic powder and heavy rare earth elements (R H ) including R H-Magnetic powder manufacturing step for manufacturing Fe-B type magnetic powder; The R L -Fe-B magnetic powder and R H -A step of mixing Fe-B type magnetic powder to produce a mixed powder; and a step of sintering the mixed powder to produce a sintered magnet; wherein R L is Nd or Pr, and the above R H Provides a method for manufacturing a rare earth sintered magnet, which is Dy or Tb.

[0013]

[0014] The above mixed powder may be a mixed powder of Nd-Fe-B type magnetic powder and Dy-Fe-B type magnetic powder, or a mixed powder of Nd-Fe-B type magnetic powder and Tb-Fe-B type magnetic powder.

[0015] The above R H -Fe-B type magnetic powder is the above R L - It may be included in the mixed powder in an amount of 1 to 30 parts by weight based on a total of 100 parts by weight of the Fe-B type magnetic powder.

[0016] The above mixed powder is NdH x (2≤x≤3), Nd 1-x Co x H y (0.1≤x≤0.5, 2≤y≤3), Nd 1-x M x (M=Fe, Co, Cu, Al, (0.1≤x≤0.5) and may include at least one rare earth alloy hydrogen compound or rare earth alloy compound selected from the group consisting of combinations thereof.

[0017] The above rare earth alloy hydrogen compound is R L - It may be included in the mixed powder in an amount of 1 to 10 parts by weight based on a total of 100 parts by weight of the Fe-B type magnetic powder.

[0018] After sintering the above mixed powder, a heat treatment step may be further included.

[0019] The above sintering may be performed at 1000 to 1100°C for 1 to 6 hours.

[0020] The above heat treatment may be performed at 1050 to 1090°C for 2 to 4 hours.

[0021] The above sintered magnet may have a coercive force of 15 kOe or more.

[0022] In addition, the present invention provides a rare earth sintered magnet manufactured by the above manufacturing method.

[0023]

[0024] The method for manufacturing a rare earth sintered magnet according to the present invention can efficiently manufacture light rare earth magnet powder and heavy rare earth magnet powder using a reduction-diffusion method (chemical synthesis method) without going through additional process steps such as a grain boundary diffusion process.

[0025] In addition, the method for manufacturing a rare earth sintered magnet according to the present invention quantitatively mixes manufactured light rare earth magnet powder and heavy rare earth magnet powder and then sintering them, thereby inducing pseudo-grain boundary diffusion that induces grain boundary diffusion of heavy rare earth (Dy, Tb) in the sintering step, thereby efficiently manufacturing a high-coercivity rare earth sintered magnet with a simple process.

[0026] In addition, the method for manufacturing a rare earth magnet according to the present invention can fill sintered powder into molds having various sizes and shapes, thereby manufacturing a high-coercivity rare earth sintered magnet without limitations in size and shape.

[0027] In addition, the high-coercivity rare earth sintered magnet manufactured by the method for manufacturing a rare earth sintered magnet according to the present invention can be widely applied to various future industries and eco-friendly energy fields, such as electric vehicle drive motors, drone / UAM propulsion motors, and wind power generators.

[0028]

[0029] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the detailed description of the present invention or the composition of the invention described in the claims.

[0030]

[0031] FIG. 1 is a schematic diagram illustrating a method for manufacturing a rare earth sintered magnet according to one embodiment of the present invention.

[0032] FIG. 2A is a schematic diagram showing the microstructure of a rare earth sintered magnet manufactured according to Example 1, and FIG. 2B is a schematic diagram showing the microstructure of a rare earth sintered magnet manufactured according to Comparative Example 1.

[0033] Figure 3A is Nd2Fe manufactured in Example 1. 14 Nd2Fe manufactured using B magnetic powder 14 B is a BH measurement graph for a sintered magnet, and Fig. 3B is a graph of Nd2Fe manufactured in Example 1. 14 B powder and Dy2Fe 14 This is a BH measurement graph for a sintered magnet manufactured by mixing B powder, and FIG. 3C is a BH measurement graph for a sintered magnet manufactured in Comparative Example 1, and FIG. 3D is a BH measurement graph for a sintered magnet manufactured in Comparative Example 2.

[0034] Figure 4A is Nd2Fe manufactured in Example 1. 14 Nd2Fe manufactured using B magnetic powder 14 B is a BH measurement graph for a sintered magnet, and Fig. 4B is a graph of Nd2Fe manufactured in Example 2. 14 B powder and Tb2Fe 14 This is a BH measurement graph for a sintered magnet manufactured by mixing B powder.

[0035] FIG. 5 shows a sintered magnet manufactured by filling a mixed powder including NdFeB powder and DyFeB powder manufactured according to Example 1 into molds having various shapes and sizes.

[0036]

[0037] It should be noted that in the following description, only the parts necessary for understanding the embodiments of the present invention are described, and the description of other parts may be omitted to the extent that it does not distract from the gist of the present invention.

[0038] The terms and words used in this specification and claims described below should not be interpreted as limited to their conventional or dictionary meanings, but should be interpreted with meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term to best describe his or her own invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are merely preferred embodiments of the present invention and do not represent all of the technical idea of ​​the present invention. Therefore, it should be understood that there may be various equivalents and modified examples that can replace them at the time of this application.

[0039]

[0040] Hereinafter, the present invention will be described in detail.

[0041] FIG. 1 is a schematic diagram of a method for manufacturing a rare earth sintered magnet according to one embodiment of the present invention.

[0042] Referring to Figure 1, the present invention relates to a method for producing rare earth elements (R) by a reduction-diffusion method. L ) including R L -Fe-B magnetic powder and heavy rare earth elements (R H ) including R H -Magnetic powder manufacturing step for manufacturing Fe-B type magnetic powder; The R L -Fe-B magnetic powder and R H- A method for manufacturing a rare earth sintered magnet is provided, comprising: a step of manufacturing a mixed powder by mixing Fe-B type magnetic powder; and a step of manufacturing a sintered magnet by sintering the mixed powder.

[0043]

[0044] First, the magnetic powder manufacturing step is to manufacture rare earth elements (R L ) including R L -Fe-B magnetic powder and heavy rare earth elements (R H ) including R H -This is the step of manufacturing Fe-B type magnetic powder.

[0045] In one embodiment, the R L is Nd or Pr, and the above R H can be Dy or Tb.

[0046] In one embodiment, the R L -Fe-B magnetic powder and R H -Fe-B type magnetic powder can be manufactured through a reduction-diffusion method.

[0047] In one embodiment, the reduction-diffusion method comprises R2Fe 14 It includes a step of synthesizing the powder of phase B and a step of washing.

[0048] The above R2Fe 14 In B, R is R L or R H It may mean .

[0049] In one embodiment, the R2Fe 14 The step of synthesizing the powder of phase B may include a step of preparing a primary mixture by mixing rare earth oxide, boron, and iron; a step of preparing a secondary mixture by adding and mixing a reducing agent such as calcium to the primary mixture; and a step of heating the secondary mixture to a temperature of 800 to 1100°C.

[0050] The above rare earth oxide is the rare earth element R, R L or RH In correspondence with, Nd2O3, Pr2O3 (or Pr6O 11 ), Dy2O3 and Tb2O3 (or Tb4O7).

[0051] The above synthesis is a method of forming R-Fe-B alloy magnet powder by mixing raw materials such as rare earth oxides, boron, and iron, and reducing and diffusion of the raw materials at a temperature of 800 to 1100°C. After synthesizing the R-Fe-B alloy magnet powder, it is cooled to room temperature, and then an inert gas (e.g., argon gas) is removed using a vacuum pump and hydrogen (H2) gas is injected to change the atmosphere to a hydrogen atmosphere. The synthesized R-Fe-B and excess rare earth metal (R) react with the hydrogen gas to form R-Fe-BH and rare earth hydride [RH] in which hydrogen is absorbed into the interstitial site of the crystal lattice. x (x=2 to 3)] is formed. As these hydrides are formed, the crystal grains expand, inducing lattice mismatch between the agglomerated crystal grains, which induces cracks and facilitates separation between the crystal grains. Hydrogen absorption can also proceed spontaneously with self-heating even at room temperature. When R-Fe-BH, in which hydrogen is absorbed between crystal lattices, is heated, the absorbed hydrogen is desorbed and restored to an R-Fe-B crystal from which hydrogen is completely removed above a certain temperature. The heating conditions for separating hydrogen can apply a heating method in a hydrogen atmosphere or a heating method in a vacuum atmosphere. When heated in a hydrogen atmosphere, the R-Fe-B crystal structure is broken down by hydrogen disproportionation above a certain temperature (e.g., 600°C) and decomposed into RH2, Fe, Fe2B, etc., so when removing hydrogen, removal is possible under vacuum conditions at a temperature below 600°C.

[0052] In one embodiment, the R2Fe 14 The synthesis of the powder of phase B can be accomplished by heating to 400°C in a hydrogen atmosphere and then applying vacuum conditions to remove hydrogen. By removing hydrogen from the hydrogen-absorbed R-Fe-BH, separation between R-Fe-B crystal particles due to shrinkage after crystal expansion can be further promoted, while at the same time, sintering imperfections due to hydrogen gas release can be controlled during the subsequent manufacture of sintered magnets.

[0053] In one embodiment, the R2Fe 14 When the powder of B phase is manufactured by mixing rare earth oxides, boron, and iron, the molar ratio of rare earth oxides, boron, and iron can be between 1:14:1 and 1.5:14:1. The rare earth oxides, boron, and iron are R2Fe 14 B is a raw material for manufacturing magnetic powder, and when the above molar ratio is satisfied, R2Fe is produced with a high yield. 14 B magnetic powder can be manufactured. If the molar ratio is less than 1:14:1, R2Fe 14 There is a problem that the composition of the B main phase is distorted and an R-rich grain boundary phase is not formed, and when the molar ratio exceeds 1.5:14:1, the amount of rare earth elements is excessive, so reduced rare earth elements remain, which may cause cohesion between particles or excessive growth of grain crystals.

[0054] The above heating, for synthesis purposes, may be carried out at a temperature of 800 to 1100°C in an inert gas atmosphere for 10 minutes to 6 hours. If the heating time is less than 10 minutes, the powder may not be sufficiently synthesized, and if the heating time is more than 6 hours, the powder size may become coarse and the primary particles may clump together.

[0055] The magnetic powder manufactured in this way is R2Fe 14 B may be. In addition, the size of the manufactured magnetic powder may be 0.5 to 10 μm, or 0.5 to 5 μm.

[0056] Typically, to form R2Fe14B magnet powder, the raw material is melted at a high temperature of 1500 to 2000°C and then rapidly cooled to form a lump of raw material, and this lump is crushed and hydrogen crushed to form R2Fe. 14 B Magnetic powder is obtained.

[0057] However, in the case of conventional methods, high temperatures are required to melt the raw materials, and then the process of cooling and crushing them is required, which makes the process time long and complicated. In addition, the R2Fe crushed in this way 14 A separate surface treatment process may be required to enhance corrosion resistance and improve electrical resistance of the B magnet powder.

[0058] However, when manufacturing R-Fe-B magnetic powder by the reduction-diffusion method according to the present invention, R2Fe is produced by reduction and diffusion of raw materials at a temperature of 800 to 1100°C. 14 B magnetic powder can be formed. Since the magnetic powder is formed in a size of several μm by the above reduction-diffusion method, there is an advantage in that there is no need to perform a separate expensive equipment such as a Jet-Mill and a mechanical grinding process.

[0059] In addition, in the process of obtaining a sintered magnet by sintering the mixed powder containing each magnetic powder thereafter, when sintering is performed in a temperature range of 1000 to 1100°C, grain growth inevitably occurs, and this grain growth acts as a factor that reduces coercivity. Since the size of the grains of the sintered magnet is directly related to the size of the initial magnetic powder, if the average size of each magnetic powder is controlled to 0.5 to 10 μm, or 0.5 to 5 μm, as in the magnetic powder according to one embodiment of the present invention, a sintered magnet with improved coercivity can be manufactured thereafter.

[0060] Additionally, the size of the alloy powder produced can be controlled by controlling the size of the iron powder used as a raw material.

[0061] In one embodiment, when manufacturing a magnetic powder by the reduction-diffusion method described above, a by-product such as calcium oxide or magnesium oxide may be generated during the manufacturing process of the magnetic powder, and thus a washing step for removing the by-product may be further included.

[0062] The above byproduct removal can be accomplished by immersing the manufactured magnetic powder in a non-aqueous solvent or a non-alcoholic solvent and washing it. When removing byproducts, if a solvent with an -OH functional group, such as an aqueous or alcoholic solvent, is used, it may oxidize the oxidation-sensitive R-Fe-B surface, causing significant problems during sintering. Therefore, it is preferable to use a non-aqueous or non-alcoholic solvent for the purpose of suppressing surface oxidation. The above washing can be repeated two or more times.

[0063] The non-aqueous solvent may include at least one of methanol, ethanol, acetone, acetonitrile, and tetrahydrofuran, and the non-alcoholic solvent may include an oil (e.g., kerosene).

[0064] Ammonium salts or acids can be dissolved in non-aqueous solvents or non-alcoholic solvents to remove by-products, specifically NH2NH2NH4, At least one of NH4NO3, NH4Cl, 2-Ethyl hexanoic acid (EHA) and ethylenediaminetetraacetic acid (EDTA) can be dissolved in a non-aqueous solvent or a non-alcoholic solvent.

[0065]

[0066] Next, the step of manufacturing the above mixed powder is to manufacture R by the reduction-diffusion method described above. L -Fe-B magnetic powder and R H -This is the step of mixing the Fe-B type magnetic powder.

[0067] In one implementation, R L -Fe-B magnetic powder and R H -When using a mixture of Fe-B type magnetic powder, R H - It is possible to overcome the disadvantages that occur when adding powders of heavy rare earth metals and heavy rare earth metal hydrides (Dy, Tb, DyH2, TbH2) or heavy rare earth-transition metal simple alloys (Dy-Cu, Dy-Fe, Dy-Co, Tb-Cu, Tb-Fe, Tb-Co, etc.) instead of Fe-B type magnet powder. Specifically, it ... elements during the sintering process. L - It can overcome the problem of not being able to properly induce the optimal coercivity enhancement effect by uniformly diffusing and dispersing inside the Fe-B crystal grains and distributing them at the particle interface of the sintered magnet. R, which has its own crystal structure and is stable at high temperatures H -Fe-B crystal grain powder R L - When mixed with Fe-B type magnet powder and sintered, the rare earth (Nd, Pr) atoms in the intergrain phase existing between grain boundaries are R H -Infiltrates into Fe-B crystal grains (R H -R substituted with Nd to form -Nd)-Fe-B H (Dy, Tb) The heavy rare earth atoms are quantitatively exchanged with the light rare earth metal atoms on the interface where the atoms are substituted. L -It is estimated that it does not penetrate uniformly into the Fe-B crystal lattice but is distributed on the interface.

[0068] In one embodiment, the mixed powder may be a mixed powder of Nd-Fe-B type magnetic powder and Dy-Fe-B type magnetic powder, or a mixed powder of Nd-Fe-B type magnetic powder and Tb-Fe-B type magnetic powder.

[0069] In one embodiment, the R H -Fe-B type magnetic powder is the above R L- It can be included in the mixed powder in an amount of 1 to 30 parts by weight, specifically 1 to 10 parts by weight, based on a total of 100 parts by weight of the Fe-B type magnetic powder, and when included in the above numerical range, an effect of improving coercivity can be expected.

[0070] In one embodiment, the heavy rare earth (Dy or Tb) is R H - It can be included at 30 wt% based on the total weight of 100 wt% of the Fe-B type magnetic powder.

[0071] In one embodiment, the mixed powder may further include a rare earth alloy hydrogen compound or a rare earth alloy compound to further promote subsequent sintering. The mixed powder may include, for example, NdH x (2≤x≤3), Nd 1-x Co x H y (0.1≤x≤0.5, 2≤y≤3), Nd 1-x M x (M=Fe, Co, Cu, Al, (0.1≤x≤0.5) and may include at least one selected from the group consisting of combinations thereof.

[0072] In one embodiment, the rare earth alloy hydrogen compound is R L - It can be included in the mixed powder in an amount of 1 to 10 parts by weight, specifically 3 to 8 parts by weight, based on a total of 100 parts by weight of the Fe-B type magnetic powder, and when included in the above numerical range, it can prevent overgrowth of crystal grains and deterioration of magnetic properties during the sintering process.

[0073]

[0074] Next, the step of manufacturing a sintered magnet is the step of sintering the above mixed powder.

[0075] In one embodiment, after sintering the mixed powder, a step of annealing at a temperature lower than the sintering temperature may be further included.

[0076] The above sintering is performed at 1000 to 1100°C for 1 to 6 hours, and when sintering is performed at the above temperature and time, the performance of a sintered magnet with high coercivity can be secured after the sintering process.

[0077] The above post-sintering heat treatment is performed at 400 to 900°C for 2 to 4 hours, and when the heat treatment is performed at the above temperature and time, a sintered magnet having sufficient sintered density and high coercive force characteristics due to the distribution of heavy rare earth elements on the grain boundary surface can be manufactured.

[0078] In one embodiment, after sintering the mixed powder, the powder is filled into molds having various sizes and shapes, and a pulsed magnetic field is applied to orient the molds to manufacture a molded body for a sintered magnet having high coercivity, as shown in FIG. 5.

[0079] In one embodiment, the sintered magnet can be manufactured by filling the above-described mixed powder into molds having various shapes and sizes, as shown in FIG. 5, so that the size and shape of the final sintered magnet can be variously controlled according to the purpose of use and needs.

[0080] In one embodiment, the sintered magnet may have a coercivity of 15 kOe or greater, or 20 kOe or greater.

[0081] In one embodiment of the present invention, a high-coercivity rare-earth sintered magnet manufactured by the above-described method for manufacturing a rare-earth sintered magnet is provided.

[0082] The above rare earth sintered magnet is (R H , R L ) may be FeB, where R L is Nd or Pr, and the above R H can be Dy or Tb.

[0083]

[0084] The above description has explained the technical idea of ​​the present invention using one embodiment. Those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present invention. Therefore, the embodiments described in the present invention are not intended to limit the technical idea of ​​the present invention, but rather to explain it, and the scope of the technical idea of ​​the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the claims, and all technical ideas within a scope equivalent thereto should be interpreted as being included within the scope of the rights of the present invention.

[0085]

[0086] <Example>

[0087] Example 1

[0088] Manufacturing of NdFeB magnetic powder

[0089] A mixture is prepared by uniformly mixing 37 g of Nd2O3, 66 g of Fe, 0.92 g of B, 0.4 g of Cu, and 17 g of Ca.

[0090] The mixture is placed in a container of any shape and size, heated and reacted at 950°C for 1 hour in an inert gas (Ar, He) atmosphere to synthesize powder. Cool to room temperature, operate a vacuum pump to remove the inert gas, then inject hydrogen (H2, 100%) gas and heat at 400°C under 1 atm of hydrogen gas for 30 minutes. Afterwards, operate a vacuum pump to remove the hydrogen, replace it with an inert gas, and cool.

[0091] Next, a washing step is performed to remove Ca and CaO, which are reaction by-products, from the reaction mixture containing NdFeB, CaO, and Ca. Specifically, 5 g of Ammonium Carbamate (NH2CO2NH4) is added and dissolved in a mixed solution of 300 ml of 2-Ethyl hexanoic acid (EHA) and 700 ml of kerosene. As a result of dissolution, a mixed solution in which EHA and its ammonium salt (Ammonium 2-Ethyl hexanoate) are simultaneously dissolved in kerosene is generated. (NH2CO2NH4 + 2 EHA ® 2 NH4-EHA + CO2) The mixed solution and the reaction mixture are put into an Attrition Mill device to simultaneously remove CaO and Ca, which are reaction by-products, and mechanically grind them, thereby performing powder washing and particle grinding. Aliphatic organic acids (EHA) and organic acid ammonium salts (NH4-EHA) are mixed in the NdFeB powder, and ammonia (NH3) is adsorbed on the surface of the NdFeB alloy powder or rare earth hydrate (RH2), thereby preventing the formation of residual carbon due to organic acid adsorption. In addition, in order to prevent the formation of residual carbon during the manufacture of sintered magnets by residual organic acids or organic acid ammonium salts, the organic substances are removed by washing twice using hexane, and the washing is completed by vacuum drying, and single phase Nd2Fe 14 B magnetic powder particles were obtained.

[0092] Manufacturing of DyFeB magnetic powder

[0093] In the production of NdFeB-based magnetic powder, single-phase Dy2Fe was produced under the same conditions and method as the production of the NdFeB-based magnetic powder, except that Dy2O3 was used instead of Nd2O3. 14 B magnetic powder particles were obtained.

[0094] Mixed powder manufacturing and sintering

[0095] Obtained Nd2Fe 145 wt% NdH2 powder and 12 wt% Dy2Fe in 100 g of B magnet powder 14 B magnet powder (corresponding to 4 wt% of Dy) is added and uniformly mixed using a paste mixer to produce a mixed powder. The mixed powder is filled into a cylindrical mold, and a pulsed magnetic field with an instantaneous magnetic field strength of 5 Tesla is applied to orient the mixed powder, thereby producing a molded body for a sintered magnet. Thereafter, the molded body is heated in a vacuum sintering furnace at 1070°C for 2 hours to perform sintering, thereby producing a sintered magnet. A schematic diagram showing the crystal structure of the sintered magnet produced is also shown in Fig. 2A.

[0096]

[0097] Example 2

[0098] In the above Example 1, Tb2O3 was used instead of Dy2O3 when manufacturing the DyFeB type magnetic powder, and a single phase Tb2Fe 14 Obtain B magnetic powder particles, Dy2Fe 14 Tb2Fe instead of B magnetic powder 14 A sintered magnet was manufactured under the same conditions and method as Example 1, except that the mixed powder was manufactured using B magnet powder.

[0099]

[0100] <Comparative Example>

[0101] Comparative Example 1

[0102] In the above Example 1, 12 wt% of Dy2Fe 14 4.8 wt% Dy instead of B magnet powder 65 Cu 35 Hydride (Dy 65 Cu 35 H x , where x is 2), except that the mixed powder was manufactured using the same conditions and method as in Example 1, and a schematic diagram showing the crystal structure of the manufactured sintered magnet is also shown in Fig. 2B.

[0103]

[0104] Comparative Example 2

[0105] In the above Example 1, 12 wt% of Dy2Fe 14 12 wt% Dy instead of B magnet powder 65 Cu 35 Hydride (Dy 65 Cu 35 H x , where x is 2), except that the mixed powder was manufactured using the same conditions and method as in Example 1, and a schematic diagram showing the crystal structure of the manufactured sintered magnet is also shown in Fig. 2B.

[0106]

[0107] <Experimental Example>

[0108] Figure 3A is Nd2Fe manufactured in Example 1. 14 Nd2Fe manufactured using B magnetic powder 14 B is a BH measurement graph for a sintered magnet, and Fig. 3B is a graph of Nd2Fe manufactured in Example 1. 14 B powder and Dy2Fe 14 This is a BH measurement graph for a sintered magnet manufactured by mixing B powder, FIG. 3C is a BH measurement graph for a sintered magnet manufactured in Comparative Example 1, and FIG. 3D is a BH (magnetic flux density-magnetic field) measurement graph for a sintered magnet manufactured in Comparative Example 2.

[0109] Referring to Figures 3A to 3D, Nd2Fe 14 B powder and Dy2Fe 14 It can be confirmed that a high-coercivity Nd-based sintered magnet can be manufactured through the sintering process alone when mixing and sintering B powder. In addition, Dy 65 Cu 35 When sintering with 12 wt% of hydrate added (Comparative Example 2), the heavy rare earth uniformly penetrates into the NdFeB crystal, resulting in 4.8 wt% of Dy 65 Cu 35It was confirmed that the characteristics were further deteriorated compared to the sintering results when hydrogen was added (Comparative Example 1).

[0110] Figure 4A is Nd2Fe manufactured in Example 1. 14 Nd2Fe manufactured using B magnetic powder 14 B is a BH measurement graph for a sintered magnet, and Fig. 4B is a graph of Nd2Fe manufactured in Example 2. 14 B powder and Tb2Fe 14 This graph shows the BH measurement for a sintered magnet manufactured by mixing B powder.

[0111] Referring to Figures 4A and 4B, Nd2Fe 14 B powder and Tb2Fe 14 It can be confirmed that when mixing and sintering B powder, a high coercivity Nd-based sintered magnet with a coercivity of 20 kOe or more can be manufactured through the sintering process alone.

[0112]

[0113] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the exemplary embodiments disclosed herein, and that various modifications may be made by those skilled in the art within the scope of the technical spirit of the invention. Furthermore, even if the operational effects of the configurations of the invention have not been explicitly described and explained while describing the exemplary embodiments of the invention, it is also to be understood that the effects predictable by the configurations should be acknowledged.

Claims

1. Rare earth elements (R) by reduction-diffusion method L ) including R L -Fe-B magnetic powder and heavy rare earth elements (R H ) including R H -Magnetic powder manufacturing step for manufacturing Fe-B type magnetic powder; The above R L -Fe-B magnetic powder and R H -A step of preparing a mixed powder by mixing Fe-B type magnetic powder; and A step of manufacturing a sintered magnet by sintering the above mixed powder; The above R L is Nd or Pr, The above R H A method for manufacturing a rare earth sintered magnet, which is Dy or Tb.

2. In paragraph 1, A method for manufacturing a rare earth sintered magnet, wherein the above mixed powder is a mixed powder of Nd-Fe-B type magnet powder and Dy-Fe-B type magnet powder, or a mixed powder of Nd-Fe-B type magnet powder and Tb-Fe-B type magnet powder.

3. In paragraph 1, The above R H -Fe-B type magnetic powder is the above R L - A method for manufacturing a rare earth sintered magnet, wherein the mixed powder is included in an amount of 1 to 30 parts by weight based on a total of 100 parts by weight of Fe-B type magnet powder.

4. In paragraph 1, The above mixed powder is NdH x (2≤x≤3), Nd 1-x Co x H y (0.1≤x≤0.5, 2≤y≤3), Nd 1-x M x A method for manufacturing a rare earth sintered magnet, comprising at least one rare earth alloy hydrogen compound or rare earth alloy compound selected from the group consisting of (M=Fe, Co, Cu, Al, (0.1≤x≤0.5) and combinations thereof.

5. In paragraph 4, The above rare earth alloy hydrogen compound is R L - A method for manufacturing a rare earth sintered magnet, wherein the mixed powder is included in an amount of 1 to 10 parts by weight based on a total of 100 parts by weight of Fe-B type magnet powder.

6. In paragraph 1, A method for manufacturing a rare earth sintered magnet, further comprising a step of heat treatment after sintering the above mixed powder.

7. In paragraph 1, A method for manufacturing a rare earth sintered magnet, wherein the above sintering is performed at 1000 to 1100°C for 1 to 6 hours.

8. In paragraph 6, A method for manufacturing a rare earth sintered magnet, wherein the above heat treatment is performed at 400 to 900°C for 2 to 4 hours.

9. In paragraph 1, A method for manufacturing a rare earth sintered magnet, wherein the above sintered magnet has a coercive force of 15 kOe or more.

10. A rare earth sintered magnet manufactured by any one of the manufacturing methods of paragraph 1.

11. In paragraph 10, The above rare earth sintered magnet is a rare earth sintered magnet having a coercive force of 15 kOe or more.

12. In paragraph 10, The above rare earth sintered magnet is (R H , R L ) may be FeB, where R L is Nd or Pr, and the above R H is a rare earth sintered magnet, which is Dy or Tb.

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