KR101252064B1 - Method for manufacturing rare earth sintered magnet using rare earth additives - Google Patents

Abstract

Method for producing a sintered magnet using a rare earth additive according to the present invention, (a) preparing a R-Fe-B-based magnet powder (wherein 'R' is a rare earth element or a combination of rare earth elements); (b) grinding the rare earth additive powder to a predetermined size or less; (c) adding and mixing the rare earth additive powder to the magnetic powder; And (d) heating the sintered mixture of the magnet powder and the rare earth additive powder to a predetermined temperature and sintering at the same time to diffuse the rare earth elements contained in the rare earth additive powder onto the surface of the magnet powder.

Description

Method for manufacturing rare earth sintered magnet using rare earth additives}

The present invention relates to a method for producing a sintered magnet, and more particularly, to a method for producing a sintered magnet using a rare earth additive.

R-Fe-B sintered magnets (where 'R' is rare earth elements such as neodymium (Nd), dysprosium (Dy), terbium (Tb), or a combination of these rare earth elements) are the highest magnetic energy known so far It is a magnet with red ((BH) max) suitable for miniaturization and light weight of parts, and has been widely applied to VCM, mobile phone, audio system, and navigation. Therefore, studies have been actively conducted to develop magnets having a higher maximum magnetic energy ((BH) max), and high-performance R-Fe-B sintered magnets having already exceeded 58 MGOe have been developed.

On the other hand, with the recent reduction of energy and environmentally friendly green growth projects, the automobile industry is actively researching hybrid cars and electric vehicles using electric motors. Since these cars are commonly driven by using electric energy, permanent magnet motors and generators are employed, and higher performance rare earth permanent magnets are required for miniaturization, light weight, and energy efficiency of automobile parts.

Magnets require high thermal capability to be applied to motors in hybrid cars that are driven at high temperatures (200-220 ° C). However, the R-Fe-B sintered magnet has a drawback that the Curie temperature is low and the temperature coefficient of coercive force (? 0.55% / ° C) is large, and the coercive force is greatly reduced at high temperature. This disadvantage can be overcome by adding Dy or Tb having a large anisotropic magnetic field to improve the coercive force.

However, these heavy rare earth elements are antiferromagnetically bonded to Fe, which lowers the saturation magnetization value, and as a result, the (BH) max value of the magnet decreases. It is also considerably more expensive than neodymium (Nd) and does not have much reserves, which can lead to resource depletion if used in the current trend. Therefore, while reducing the content of Dy or Tb, the research to increase the coercive force of the sintered magnet is being actively conducted

An object of the present invention is to provide a method for producing a sintered magnet using a rare earth additive capable of improving the coercive force of the sintered magnet while reducing the content of rare earth elements such as dysprosium (Dy) in the sintered magnet.

The object is the steps of (a) preparing a R-Fe-B-based magnetic powder, wherein 'R' is a rare earth element or a combination of rare earth elements; (b) grinding the rare earth additive powder to a predetermined size or less; (c) adding and mixing the rare earth additive powder to the magnetic powder; And (d) heating the sintered mixture of the magnet powder and the rare earth additive powder to a predetermined temperature and sintering the same, and simultaneously diffusing the rare earth element contained in the rare earth additive powder onto the surface of the magnet powder. It is achieved by a method for producing a sintered magnet using a rare earth additive.

In the step (b), the rare earth additive powder may be pulverized to below 1 μm average particle size.

The rare earth additive may comprise a rare earth oxide.

The magnetic powder is Nd _{(30 ~ 33) -x} Dy _x Fe _{bal .} It has a B ₁ composition (x: 0 ~ 10 wt%), the rare earth oxide is dysprosium oxide (Dy ₂ O ₃ ), the step (c) is the rare earth oxide powder in a mixing ratio of 0.5 to 10.0 wt% It can be mixed with magnetic powder.

The rare earth additive may include rare earth fluorides.

The magnetic powder is Nd _{(30 ~ 33) -x} Dy _x Fe _{bal .} B ₁ a composition having (where, x: 0 ~ 10 wt% ), the rare earth fluoride is fluoride, dysprosium (DyF _3), and wherein step (c) the magnetic powder for the rare-earth fluoride powder at a mixing ratio of 0.5 to 10.0 wt% Can be mixed with

In the step (c), the magnetic powder and the rare earth additive powder may be mixed using a solvent, and then dried in a vacuum to remove the solvent.

In the step (d), the predetermined temperature may have a range of 1040 to 1090 ℃.

Step (a) comprises the steps of: (a1) preparing an alloy strip of R-Fe-B composition; (a2) performing hydrotreating on the alloy strip; (a3) performing a dehydrogenation treatment on the alloy strip; And (a4) pulverizing the alloy strip to form the magnetic powder.

The step (a2) may include forming a vacuum in the chamber after charging the alloy strip into a chamber; Injecting hydrogen into the chamber; Maintaining the first set temperature for a first set time after heating the temperature in the chamber to a first set temperature; And injecting an inert gas into the chamber to cool the alloy strip, wherein step (a3) comprises: forming a vacuum in the chamber; Maintaining the second set temperature for a second set time after heating the temperature in the chamber to a second set temperature; And injecting an inert gas into the chamber to cool the alloy strip.

The first set temperature is in the range of 350 to 450 ℃, the magnetic powder may have an average particle size of 3 to 7 ㎛.

According to the present invention, a rare earth oxide powder or a rare earth fluoride powder pulverized to a predetermined size or less is added to an R-Fe-B-based magnet powder, followed by mixing and heating the mixture to a predetermined temperature to sinter the rare earth oxide powder or rare earth. By diffusing the rare earth elements contained in the fluoride powder onto the surface of the magnet powder, the coercive force of the sintered magnet can be improved while reducing the content of rare earth elements such as dysprosium (Dy) in the sintered magnet.

1 is a schematic flowchart of a method of manufacturing a rare earth sintered magnet according to an embodiment of the present invention.
FIG. 2 is a flowchart of a step of preparing a magnet powder in the method of manufacturing the rare earth sintered magnet of FIG. 1.
3 is a flowchart of a step of mixing the magnet powder and the rare earth oxide powder in a wet mixing method in the method of manufacturing the rare earth sintered magnet of FIG. 1.
4 is Dy ₂ O ₃ used for mixing in Experimental Example 1-1 The SEM image of the powder ((a) is high magnification, (b) is low magnification).
5 shows the potato curve of the sintered magnet prepared in Experimental Example 1-1.
FIG. 6 shows SEM images ((a) is high magnification and (b) is low magnification) of Dy ₂ O ₃ powder ground in a planetary mill for 30 minutes in Experimental Example 1-2.
7 shows the potato curve of the sintered magnets prepared in Experimental Example 1-2.
8 is a schematic flowchart of a method of manufacturing a rare earth sintered magnet according to another embodiment of the present invention.
9 is DyF ₃ used for mixing in Experimental Example 2 The SEM image of the powder ((a) is high magnification, (b) is low magnification).
10 shows the potato curve of the sintered magnets prepared in Experimental Example 2.

In order to fully understand the present invention, operational advantages of the present invention, and objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the accompanying drawings which illustrate preferred embodiments of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in order to avoid unnecessary obscuration of the present invention.

1 is a schematic flowchart of a method of manufacturing a sintered magnet using a rare earth additive according to an embodiment of the present invention, FIG. 2 is a flowchart of preparing magnetic powder in the method of manufacturing the sintered magnet of FIG. 1, and FIG. 3. 1 is a flowchart of a step of mixing the magnetic powder and the rare earth oxide powder in a wet mixing method in the method of manufacturing the sintered magnet of FIG. 1.

Referring to FIG. 1, in the method of manufacturing a sintered magnet using the rare earth additive according to the present embodiment, a step (S110) of preparing an R-Fe-B-based magnet powder and grinding the rare earth oxide powder to a predetermined size or less Step S120, adding and mixing the rare earth oxide powder to the magnetic powder (S130), heating the mixture of the magnet powder and the rare earth oxide powder to a predetermined temperature, and sintering at the same time to the rare earth oxide powder on the surface of the magnetic powder It may include the step (S140) to diffuse the included rare earth element on the surface of the magnet powder. Here, 'R' represents rare earth elements such as neodymium (Nd, neodymium), dysprosium (Dy, dysprosium), terbium (Tb, terbium), or a combination of these rare earth elements.

First, the step of preparing the R-Fe-B-based magnet powder (S110), as shown in Figure 2, the step of producing an alloy strip of the R-Fe-B composition (S111) and the prepared alloy strip And performing a dehydrogenation treatment on the hydrogenated alloy strip (S115), and grinding the dehydrogenation alloy strip to form magnet powder (S117). Can be.

In step S111, the alloy of R-Fe-B composition may be dissolved and rapidly cooled through a strip caster to prepare an alloy strip having a thickness of about 0.2 to 0.4 mm.

In step S113, a predetermined time (for example, about 2 hours) at a temperature in the range of preferably 350 to 450 ° C. (more preferably around 400 ° C.) at a predetermined hydrogen pressure (for example, about 0.1 MPa) for the prepared alloy strip. Hydrogen treatment may be carried out. Specifically, the hydrogen treatment step (S113), the step of forming a vacuum in the chamber after charging the alloy strip prepared in step S111 in a predetermined chamber (S113a), and injecting hydrogen into the chamber (S113b) and And maintaining the first set temperature for a first set time after heating the temperature in the chamber to the first set temperature (S113c), and injecting an inert gas into the chamber to cool the alloy strip (S113d). Can be. At this time, the vacuum in the chamber in step S113a is approximately 1 × 10 ⁻³ torr, and in step S113b, hydrogen may be injected to about 0.1 MPa.

On the other hand, in step S113c, the first set temperature, that is, the hydrotreating temperature, preferably has a range of 350 to 450 ° C. (more preferably around 400 ° C.), which is repeatedly changed within a range of 20 to 500 ° C. As the hydrotreatment temperature increases, the residual magnetization value of the sintered magnet is similar, but the coercivity of the sintered magnet tends to increase. On the other hand, this is because the coercivity decreases again when hydrogen treatment is performed at around 500 ° C. This experimental result is considered to be because the shape of the magnet powder changes microscopically as the hydrogen treatment temperature changes, and this change determines the degree of non-uniform hydrogen absorption between the inside and outside of the magnet powder. That is, the magnet powder prepared after the hydrogen treatment at 25 to 300 ℃ is crushed while the Nd-rich phase that causes the formation of reverse magnetic spheres are contained in the particles of the magnetic powder to some extent, compared to the hydrogen powder at 400 ℃ The magnetic powder is considered to have increased coercive force because the Nd-rich phase is relatively evenly distributed on the outside of the magnetic powder without such a portion, and thus a magnetic insulating layer is formed more uniformly after sintering. On the other hand, in the case of hydrogen treatment at 500 ° C or higher, the separation of the Nd-rich phase occurs excessively, and many parts exist as independent fine powders and are separated from the grinding process or exist in the form of Nd-rich pockets after sintering, and thus do not contribute significantly to the increase in coercivity. It seems to be. For reference, the first set time may be about 2 hours. Meanwhile, in the step S113d, an inert gas such as argon (Ar) is injected into the chamber to cool the alloy strip in the chamber. At this time, using an inert gas as a refrigerant for cooling the alloy strip is unnecessary in the cooling process. This is to suppress the occurrence.

In step S115, the hydrogenated alloy strip may be heated to about 550 ° C. in a vacuum chamber to remove hydrogen absorbed by the alloy strip. Specifically, the dehydrogenation step (S115), forming a vacuum in the chamber (S115a), and heating the temperature in the chamber to the second set temperature and maintaining the second set temperature for a second set time ( S115b) and injecting an inert gas into the chamber to cool the alloy strip (S115b). At this time, the second set temperature, that is, the dehydrogenation temperature is preferably in the range of 500 to 600 ℃, the second set time is preferably about 10 hours.

In step S117, the dehydrogenated alloy strip may be pulverized into a powder having an average particle size of 3 to 7 μm to form a magnetic powder. That is, it is preferable that the magnet powder has an average particle size of 3 to 7 μm so as to be smoothly mixed with the rare earth oxide powder to exhibit the required magnetic performance.

Next, the step of grinding the rare earth oxide powder to a predetermined size or less (S120). At this time, the grinding operation for the rare earth oxide powder may be performed by a fine mill such as a jet mill, a ball mill, or the like. The rare earth oxide powder may comprise dysprosium oxide powder. That is, the rare earth oxide may include dysprosium oxide (Dy ₂ O ₃ ). However, the rare earth oxide in the present invention is not limited to dysprosium oxide (Dy ₂ O ₃ ). Meanwhile, in step S120, the rare earth oxide powder such as Dy ₂ O ₃ powder is pulverized to 1 µm or less in average particle size, that is, the predetermined size in step S120 is preferably 1 µm in average particle size. It will be described in detail through Experimental Example 1-1 and Experimental Example 1-2.

Next, the rare earth oxide powder may be added to the magnetic powder and mixed (S130). 3 illustrates a process of mixing the rare earth oxide powder with a magnetic powder by wet mixing. Referring to FIG. 3, the mixing step (S130) includes mixing the magnetic powder and the rare earth oxide powder with a solvent (S131). In addition, the mixture solution may be dried in a vacuum to remove the solvent from the mixture solution to obtain a dried mixture (S133). That is, in step S130, the magnetic powder and the rare earth oxide powder may be mixed using a solvent, and then dried in a vacuum to remove the solvent. In this case, the solvent for dissolving the magnetic powder and the rare earth oxide powder may be cyclohexane. And the like can be used. When the magnetic powder and the rare earth oxide powder are mixed using this wet mixing method, a more uniform mixing can be achieved between the magnetic powder and the rare earth oxide powder than the dry mixing, which leads to the aggregation of the rare earth oxide in the mixing process. As a result, the phenomenon that the residual magnetic flux density falls can be reduced. However, in the present invention, the mixing operation of the magnetic powder and the rare earth oxide powder is not limited to the above wet mixing method. That is, the mixing operation of the magnet powder and the rare earth oxide powder may be performed by a dry mixing method without using a solvent. In Experimental Examples 1-1 and 1-2, which will be described below, magnets are used by using a dry mixing method. The powder and rare earth oxide powder were mixed.

Next, a step of heating and sintering the mixture of the magnet powder and the rare earth oxide powder at a predetermined temperature may be performed to diffuse the rare earth elements included in the rare earth oxide powder onto the surface of the magnet powder (S140). That is, in the present invention, the process of diffusing the rare earth element included in the rare earth oxide powder on the surface of the magnet powder is not performed separately from the sintering process, but is simultaneously performed in the process of sintering the magnet powder. Accordingly, there is an advantage that the entire manufacturing process can be simplified by omitting a separate heat treatment process for diffusing the rare earth element on the surface of the magnet powder. Here, the 'predetermined temperature' preferably has a range of 1040 to 1090 ℃, which is not only the sintering action of the magnet powder in this temperature range, but also the effect of diffusing the rare earth elements contained in the rare earth oxide powder on the surface of the magnet powder This is because it goes smoothly. On the other hand, prior to the step S140, in the case of the anisotropic magnet powder, a step (not shown) of the magnetic powder obtained by the step S130 to dry or wet magnetic field molding under a certain size of the magnetic powder mixture may be further performed. have. For reference, after the step S140, a heat treatment step for improving the magnetic properties of the sintered magnet may be performed.

Hereinafter, with reference to FIGS. 4 to 7 will be described in detail the working effect of the manufacturing method of the sintered magnet using the rare earth additive according to the present embodiment. 4 is Dy ₂ O ₃ used for mixing in Experimental Example 1-1 SEM image of the powder is shown ((a) is a high magnification, (b) is a low magnification), Figure 5 shows the potato curve of the sintered magnet prepared in Experimental Example 1-1, Figure 6 is a planetary mill in Experimental Example 1-2 SEM image of Dy ₂ O ₃ powder pulverized for 30 minutes through ((a) is a high magnification, (b) is a low magnification), Figure 7 shows the potato curve of the sintered magnets prepared in Experimental Example 1-2.

(Experimental Example 1-1)

(1) Experimental method

In the present Experimental Example _{Nd 26 .1 Dy 6 .5 Fe bal} . After dissolving the alloy of the B ₁ composition was rapidly cooled through a strip caster to prepare an alloy strip having a thickness of about 0.2 ~ 0.4 mm. In this case, the subscript in the formula has units of wt%. The prepared alloy strip was subjected to hydrotreating at 400 ° C. for 2 hours at a hydrogen pressure of 0.1 MPa, and then heated to a temperature of 550 ° C. under vacuum to remove hydrogen. Hydrogen / dehydrogenated alloy strips were ground using a jet mill to produce magnetic powder of about 5-6 μm. A small amount of Dy ₂ O ₃ powder was added to the prepared magnetic powder, followed by dry mixing. The mixed powder was uniaxially formed under 1.9 T of magnetic field and vacuum-sintered at 1070 ° C. for 4 hours. After sintering, the first heat treatment was performed at 850 ° C. for 2 hours, followed by the second and third heat treatments at 530 ° C. and 500 ° C. for 2 hours, respectively. The shape and distribution of the prepared powder and the microstructure of the sintered body were analyzed by Scanning Electron Microscopy (Hitachi S-3000N), and the magnetic properties of the sintered body (Sintered magnet) were measured by BH loop tracer ) Was measured.

(2) Experimental result analysis

4 is Dy ₂ O ₃ used for mixing It shows a picture of the powder. As shown in FIG. 4, Dy ₂ O ₃ The average particle size of the powder was 3.5 μm, but the coarse powder of about 15 μm was also included. Such Dy ₂ O ₃ The powder 2 wt% (amount added to the target content of the sintered magnet so that Dy _{8.1 wt%) Nd 26 .1 Dy} 6 .5 Fe bal. The potato curve of the sintered magnet prepared by mixing with the magnet powder of the B ₁ composition is shown by a dotted line in FIG. Mixing the solid line I in Fig. _{5 Nd 26 .1 Dy 6 .5 Fe} bal. B ₁ represents a sintered magnet demagnetization curve of the composition. Dy ₂ O ₃ After mixing the powder, as shown by the dotted line, it was confirmed that the coercive force was greatly increased by the effect of the addition of Dy. However, the residual magnetic flux density (Br) and maximum magnetic energy ((BH) max) values decreased, and the permanent magnet performance index, that is, (BH) max + iHc values, also decreased. This decrease is the coarse Dy ₂ O ₃ It is believed that this is because the nonmagnetic phase increased because the powder was not decomposed and remained as it was.

(Experimental Example 1-2)

(1) Experimental method

In the present Experimental Example _{Nd 26 .1 Dy 6 .5 Fe bal} . The process of preparing the magnet powder of the B ₁ composition was performed in the same manner as the above-described experimental example. On the other hand, Dy ₂ O ₃ powder is _{Nd 26 .1 Dy 6 .5 Fe bal} . Prior to dry mixing with the magnet powder of B ₁ composition, it was ground for 30 minutes using a planetary mill to have an average particle size of 1 μm or less. 6 shows a photograph of Dy ₂ O ₃ powder ground for 30 minutes through a planetary mill. After grinding, as shown in FIG. 6, it could be confirmed that the powder was uniformly pulverized into Dy ₂ O ₃ powder having a size of about 1 μm, and the pulverized Dy ₂ O ₃ powder was aggregated to various sizes. The pulverized Dy ₂ O ₃ powder has a target Dy content of 6.9 to 8.1 wt%, that is, 0.5 to 2 wt% of Nd _26.1 Dy _6.5 Fe _bal. The sintered magnet was manufactured by substantially mixing with the magnet powder having the composition of B ₁ and undergoing substantially the same procedure as described above.

(2) Experimental result analysis

Potato curves of the sintered magnets prepared as described above are illustrated in FIG. 7. As shown in FIG. 7, as the amount of Dy ₂ O ₃ added increased, the coercive force increased and the residual magnetic flux density decreased. Also, 2 wt% of Dy ₂ O ₃ Compared to the case where the powder was mixed (Dy 8.1 wt% in the sintered magnet), Dy ₂ O ₃ It was found that the magnetic properties were improved compared to the sintered magnet (see FIG. 5) prepared by mixing the powder without grinding.

On the other hand, in Test Example 1-1 and Experimental Examples 1-2 above, Nd ₂₆ Dy _{6 .1 .5} Fe _bal. Magnetic powder having a B ₁ composition and Dy ₂ O ₃ powder having a mixing ratio of 0.5 to 2 wt% were used, but this is merely exemplary and the present invention is not limited thereto. Preferably, Nd ₍ 30-33 _{) -x} Dy _x Fe _{bal .} Dy ₂ O ₃ powder may be mixed in a magnetic powder having a B ₁ composition (wherein, x: 0 to 10 wt%) at a mixing ratio of 0.5 to 10.0 wt%.

8 is a schematic flowchart of a method of manufacturing a sintered magnet using a rare earth additive according to another embodiment of the present invention. Hereinafter, a method of manufacturing a sintered magnet using a rare earth additive according to another embodiment of the present invention will be described based on differences from the above-described embodiment.

Referring to FIG. 8, in the method of manufacturing a sintered magnet using the rare earth additive according to the present embodiment, a step of preparing R-Fe-B-based magnet powder (S210) and grinding the rare earth fluoride powder to a predetermined size or less Step S220, adding the rare earth fluoride powder to the magnetic powder and mixing (S230), heating the mixture of the magnetic powder and the rare earth fluoride powder to a predetermined temperature and sintering at the same time to the rare earth fluoride powder on the surface of the magnetic powder It may include the step (S240) to diffuse the included rare earth element on the surface of the magnet powder. Here, 'R' represents rare earth elements such as neodymium (Nd, neodymium), dysprosium (Dy, dysprosium), terbium (Tb, terbium), or a combination of these rare earth elements.

Except for using the rare earth fluoride powder in place of the rare earth oxide powder of the above-described embodiment, the additive mixing the magnetic powder with the magnetic powder in order to improve the coercive force of the sintered magnet is used. As the manufacturing method of the sintered magnet using the rare earth additive according to the above embodiment is substantially the same (that is, the steps S210, S220, S230 and S240 respectively correspond to the steps S110, S120, S130 and S140 in the above-described embodiment). ), S210, S220, S230 and S240 steps are detailed steps and detailed description thereof will apply mutatis mutandis to the above-described embodiment.

Meanwhile, the rare earth fluoride powder may include dysprosium fluoride powder. That is, the rare earth fluoride may be dysprosium fluoride (DyF ₃ ). However, the rare earth fluoride in the present invention is not limited to dysprosium fluoride (DyF ₃ ).

As described above, the sintered magnet prepared by mixing the rare earth fluoride powder has the advantage that the coercive force is significantly improved than the sintered magnet prepared by mixing the rare earth oxide powder under the same conditions. On the other hand, in terms of the reduction of the residual magnetic flux density, it can be said that the sintered magnets prepared by mixing the rare earth oxide powders as in the above-described embodiments have advantages over the sintered magnets prepared by mixing the rare earth fluoride powders.

Hereinafter, with reference to FIGS. 9 and 10 will be described in detail the working effect of the manufacturing method of the sintered magnet using the rare earth additive according to the present embodiment. 9 is DyF ₃ used for mixing in Experimental Example 2 SEM image of the powder is shown ((a) is a high magnification, (b) is a low magnification), Figure 10 shows the potato curve of the sintered magnets prepared in Experimental Example 2.

(Experimental Example 2)

(1) Experimental method

In the present Experimental Example _{Nd 26 .1 Dy 6 .5 Fe bal} . The process of preparing the magnet powder of the B ₁ composition was performed in the same manner as the above-described experimental examples. On the other hand, DyF ₃ powder was provided through a grinding process to have an average particle size of 1 ㎛ or less as shown in FIG. Referring to FIG. 9 (b), it was found that the DyF ₃ powder was partially aggregated as in the above-described pulverized Dy ₂ O ₃ powder of Experimental Example 1-2. The DyF ₃ powder was _0.1, i.e., 0.5 ~ 2 wt% Dy such that the target content is 6.9 ~ 8.1 wt% in the final magnet Nd ₂₆ Dy _{6 .5} Fe _bal. The sintered magnet was manufactured by substantially mixing with the above-described experimental examples by mixing with B ₁ composition of the magnetic powder.

(2) Experimental result analysis

Potato curves of the sintered magnets prepared as shown above are shown in FIG. Referring to FIG. 10, similar to the magnetic properties (see FIG. 7) of the sintered magnet prepared by mixing Dy ₂ O ₃ powder in the above-described experimental example, the coercivity increased as the amount of DyF ₃ increased, and the residual magnetic flux density. And maximum magnetic energy ((BH) max) values were reduced. On the other hand, the increase of the coercive force and the decrease of the residual magnetic flux density were larger than the case of mixing the Dy ₂ O ₃ powder.

On the other hand, in the above Experimental Example 2, Nd ₂₆ Dy _{6 .1 .5} Fe _bal. A magnet powder having a B ₁ composition and a DyF ₃ powder having a mixing ratio of 0.5 to 2 wt% were used, but this is merely exemplary and the present invention is not limited thereto. Preferably, Nd ₍ 30-33 _{) -x} Dy _x Fe _{bal .} The DyF ₃ powder may be mixed in a 0.5-10.0 wt% mixing ratio to a magnetic powder having a B ₁ composition (wherein, x: 0 to 10 wt%).

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Accordingly, such modifications or variations are intended to fall within the scope of the appended claims.

For example, the above-described embodiments show rare earth oxide powders such as Dy ₂ O ₃ and rare earth fluoride powders such as DyF ₃ as 'rare earth additive powders' added and mixed with the magnet powder, but the present invention is not limited thereto. . That is, the technical idea of the present invention may also be realized by adding and mixing a powder of rare earth oxides and other rare earth additives (for example, rare earth hydrides such as DyH2 and DyH3) to the magnetic powder.

Claims (11)

(a) preparing an R-Fe-B-based magnet powder, wherein 'R' is a rare earth element or a combination of rare earth elements;
(b) grinding the rare earth additive powder to a predetermined size or less;
(c) adding and mixing the rare earth additive powder to the magnetic powder; And
(d) heating the sintered mixture of the magnet powder and the rare earth additive powder to a predetermined temperature and sintering at the same time to diffuse the rare earth elements contained in the rare earth additive powder onto the surface of the magnet powder,
The step (a) comprises the steps of: (a1) preparing an alloy strip of R-Fe-B composition, (a2) performing hydrotreating on the alloy strip, and (a3) dehydrogenating the alloy strip. Performing a treatment, and (a4) grinding the alloy strip to form the magnetic powder,
The step (a2) may include forming a vacuum in the chamber after charging the alloy strip into a chamber, injecting hydrogen into the chamber, and heating the temperature in the chamber to a first predetermined temperature. Maintaining the first set temperature for a set time, and injecting an inert gas into the chamber to cool the alloy strip;
The step (a3) may include forming a vacuum in the chamber, maintaining the second set temperature for a second set time after heating the temperature in the chamber to a second set temperature, and inactivating the chamber. The method of manufacturing a sintered magnet using a rare earth additive, comprising the step of injecting a gas to cool the alloy strip.
The method of claim 1,
The step (b)
Method for producing a sintered magnet using a rare earth additive, characterized in that the rare earth additive powder is pulverized to less than 1 ㎛ average particle size.
The method of claim 1,
The rare earth additive is a method of producing a sintered magnet, characterized in that it comprises a rare earth oxide.
The method of claim 3,
The magnetic powder is Nd _{(30 ~ 33) -x} Dy _x Fe _{bal .} Has a B ₁ composition, where x: 0-10 wt%
The rare earth oxide is dysprosium oxide (Dy ₂ O ₃ ),
In the step (c), the rare earth oxide powder is mixed with the magnet powder in a mixing ratio of 0.5 to 10.0 wt%.
The method of claim 1,
The rare earth additive is a method of producing a sintered magnet, characterized in that it comprises a rare earth fluoride.
The method of claim 5,
The magnetic powder is Nd _{(30 ~ 33) -x} Dy _x Fe _{bal .} Has a B ₁ composition, where x: 0-10 wt%
The rare earth fluoride is dysprosium fluoride (DyF ₃ ),
In the step (c), the rare earth fluoride powder is mixed with the magnet powder in a mixing ratio of 0.5 to 10.0 wt%.
The method of claim 1,
The step (c)
The magnet powder and the rare earth additive powder is mixed using a solvent, and then dried in a vacuum to remove the solvent, characterized in that the manufacturing method of the sintered magnet using the rare earth additive.
The method of claim 1,
In the step (d)
The predetermined temperature is a method of producing a sintered magnet using a rare earth additive, characterized in that it has a range of 1040 ~ 1090 ℃.
delete delete The method of claim 1,
The first set temperature is in the range of 350 to 450 ℃,
The magnet powder is a method of producing a sintered magnet using a rare earth additive, characterized in that having an average particle size of 3 to 7 ㎛.

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