KR101261099B1 - method for manufacturing rare earth sintering magnets - Google Patents

Abstract

The rare earth sintered magnet manufacturing method of the present invention comprises the steps of preparing a rare earth magnetic powder for rare earth sintered magnet; Mixing the rare earth magnetic powder with a liquid solvent to form a rare earth magnetic powder slurry; After filling the rare earth magnetic powder slurry to a mold, by pressing the rare earth magnetic powder slurry by a punch to discharge the liquid solvent of the rare earth magnetic powder slurry to the outside of the mold to form a filler of the rare earth magnetic powder, The rare earth magnetic powder has a filling density for increasing the orientation ratio of the rare earth magnetic powder; Applying a magnetic pulse to the filler in the mold by using a magnetic coil to orient the rare earth magnetic powder of the filler, and applying the pulse magnetic field one or more times to increase the orientation ratio of the rare earth magnetic powder; Separating the filler from the mold; And sintering the filler.

Description

Method for manufacturing rare earth sintering magnets

The present invention relates to a rare earth sintered magnet manufacturing method, and more particularly to a method of manufacturing a rare earth sintered magnet to simplify the manufacturing process using a wet pulse magnetic field orientation technique.

Generally, a butterfly shape used for a voice coil motor such as a hard disk drive (HDD) or a DVD (DVD), a disk used for a coreless motor ( Block-shaped rare earth sintered magnets used for disk or coin shape, servo motor and linear motor have a maximum magnetic energy of 40-48 MGOe.

According to the trend of miniaturization and high performance of parts and finished products utilizing rare earth sintered magnets, rare earth sintered magnets having better magnetic properties are required. In order to obtain such excellent magnetic properties, for example, the maximum magnetic energy, it is essential to improve the magnetic field forming technology in which the rare earth magnetic powder is oriented in the magnetic field application direction and molded in the rare earth sintered magnet manufacturing process. The magnetic field shaping technology currently widely used includes a static magnetic field longitudinal shaping technology and a static magnetic field transverse shaping technology.

The static magnetic field longitudinal shaping technology fills the mold with a rare earth magnetic powder pulverized to a size of 2 to 10 μm, applies a static magnetic field of 10 to 20 KOe to the rare earth magnetic powder and orients the rare earth magnetic powder in the magnetic field direction, followed by a rare earth magnetic field. The rare earth magnetic powder is molded while applying compressive stress to the powder in a direction parallel to the magnetic field direction. However, the static magnetic field longitudinal shaping technology uses a magnetic field generated by an electromagnet, for example, an electromagnet having an iron core in the center and a coil wound around the periphery to orient the rare earth magnetic powder. Difficult to increase Therefore, the static magnetic field longitudinal shaping technology can obtain rare earth sintered magnets having an orientation ratio of 85 to 90%, and obtain a maximum magnetic energy of 38 to 40 MGOe. Therefore, the rare earth sintered magnets have relatively low magnetic properties.

In the static magnetic field transverse shaping technology, the rare earth magnetic powder ground to a size of 2 to 10 µm is filled into the mold, and the rare earth magnetic powder is oriented in the magnetic field direction by applying a static magnetic field of 10 to 20 KOe to the rare earth magnetic powder, followed by the rare earth magnetic field. The rare earth magnetic powder is molded while applying compressive stress to the powder in a direction perpendicular to the magnetic field direction. By the way, the static magnetic field transverse shaping technology can improve the orientation ratio of the rare earth magnetic powder to 90-95% at the time of molding and obtain a maximum magnetic energy of about 44 MGOe, thereby producing a rare earth sintered magnet having high magnetic properties. However, unlike the static magnetic field longitudinal molding technique, the static magnetic field transverse molding technique is difficult to form a rare earth magnetic powder compact having a complicated shape such as a butterfly shape, a disk shape or a coin shape. Therefore, in order to manufacture a rare earth sintered magnet having a complex shape using the static magnetic field transverse shaping technology, a separate process of magnetic field shaping and sintering of the rare earth magnetic powder into a block shape, and then processing into a final product shape Work should be further performed. Therefore, static field transverse shaping technology is less economical than static field longitudinal shaping technology in terms of manufacturing cost.

Currently, there is a need for an improved technology for simplifying the manufacturing process of rare earth sintered magnets to lower the manufacturing cost and improving the magnetic properties of the rare earth sintered magnets.

Accordingly, it is an object of the present invention to simplify the manufacturing process of rare earth sintered magnet to lower the manufacturing cost.

Another object of the present invention is to improve the magnetic properties of rare earth sintered magnets.

In order to achieve the above object, the rare earth sintered magnet manufacturing method according to the present invention comprises the steps of preparing a rare earth magnetic powder for rare earth sintered magnet; Mixing the rare earth magnetic powder with a liquid solvent to form a rare earth magnetic powder slurry; After filling the rare earth magnetic powder slurry to a mold, by pressing the rare earth magnetic powder slurry by a punch to discharge the liquid solvent of the rare earth magnetic powder slurry to the outside of the mold to form a filler of the rare earth magnetic powder, The rare earth magnetic powder has a filling density for increasing the orientation ratio of the rare earth magnetic powder; Applying a magnetic pulse to the filler in the mold by using a magnetic coil to orient the rare earth magnetic powder of the filler, and applying the pulse magnetic field one or more times to increase the orientation ratio of the rare earth magnetic powder; Separating the filler from the mold; And sintering the filler.

Preferably, the forming of the filler includes: filling the rare earth magnetic powder slurry by injecting the slurry into a mold by using a slurry injection device; Disposing an upper punch on an upper side of the mold; And pressing the rare earth magnetic powder slurry by the upper punch and the lower punch of the mold to discharge the liquid solvent of the rare earth magnetic powder slurry to form the filler.

Preferably, the rare earth magnetic powder can be mixed with a liquid solvent having a concentration of 10 to 50 wt%.
Preferably, the rare earth magnetic powder can be filled at a packing density of 2.0 to 4.0 g / cc.
Preferably, the pulse magnetic field can be applied one or more times in the range of 10 to 80 KOe.

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According to the present invention, it is not necessary to perform a separate molding process after the magnetic field alignment process, and by forming the rare earth magnetic powder filler into the same shape as the final product, a separate additional processing process for the shape of the final product is performed. Since there is no need to proceed, the manufacturing process can be simplified to shorten the manufacturing time and lower the manufacturing cost. In addition, it is possible to obtain magnetic properties of 45 MGOe or more exceeding the limit of the characteristics obtainable in the static field longitudinal axis forming technique or the static field diaphragm forming technique.

1 is a process flow chart showing a rare earth sintered magnet manufacturing method according to the present invention.
2A to 2D are process flowcharts showing the wet pulse magnetic field longitudinal alignment method applied to the rare earth sintered magnet manufacturing method according to the present invention.

Hereinafter, a rare earth sintered magnet manufacturing method according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a process flow chart showing a rare earth sintered magnet manufacturing method according to the present invention, Figures 2a to 2d is a process flow chart showing a wet pulse magnetic field longitudinal alignment method applied to the rare earth sintered magnet manufacturing method according to the present invention.

1 and 2a to 2d, first, in the rare earth magnetic powder manufacturing step (S10), to prepare a rare earth magnetic powder (1) for the rare earth sintered magnet.

In more detail, in the mixing step (S11), the alloy composition corresponding to the rare earth magnetic powder (1) for the rare earth sintered magnet, for example 27 ~ 36wt% RE-64 ~ 73wt% Fe-0 ~ 5wt% The raw materials of RE, Fe, TM, and B are respectively weighed so as to have a composition of TM-0 to 2 wt% B (here, RE: rare earth element and TM: 3d transition metal), and these raw materials are mixed. Subsequently, in the dissolution step (S13), these mixed raw materials are melted by a dissolution method, for example, a vacuum induction heating method or the like to form an alloy molten metal. Then, in the quench solidification step (S15), the molten alloy is quench solidified by, for example, strip casting, chilled mold casting, or the like to form an alloy ingot. Then, in the hydrotreatment / dehydrogenation step (S17), in order to improve the grinding capacity of the alloy ingot, for example, in a hydrogen gas atmosphere of 0.1 to 10 atm and a temperature of room temperature to 600 ° C. for 0.5 to 8 hours. The alloy ingot is heated to hydrogenate the alloy ingot. Subsequently, the alloy ingot is dehydrogenated by heating the alloy ingot for 0.5 to 10 hours at a vacuum of ¹ × 10 ⁻¹ Torr or less and a temperature of 700 to 900 ° C., for example. Then, in the grinding step (S19), for example, by grinding the alloy ingot using a grinding method such as a jet mill, atrita mill, ball mill, vibration mill, etc., for example, a uniform having a particle size of 2 ~ 10㎛ To prepare a fine rare earth magnetic powder (1). Here, the process of manufacturing the rare earth magnetic powder which has a particle size of 2-10 micrometers from an alloy ingot is performed in nitrogen gas or an inert gas atmosphere. This is to prevent the rare earth magnetic powder from contaminating with oxygen and deteriorating magnetic properties.

Then, in the slurry forming step (S20), the rare earth magnetic powder prepared in the rare earth magnetic powder production step (S10) of the liquid solvent (3) having a concentration of 10 to 50wt%, such as nucleic acid or alcohol, etc. The rare earth magnetic powder slurry 5 is mixed with the organic solvent. On the other hand, since the liquidity of the rare earth magnetic powder 1 is not improved unless the liquid solvent 3 is included, the rare earth magnetic powder 1 cannot be sufficiently oriented in a subsequent alignment step (S40), and more than 50% of the liquid solvent. If (3) is included, the work to remove a part of the excess liquid solvent (3) before the alignment step (S40) should be added.

Then, in the slurry filling step (S30), the rare earth magnetic powder slurry (5) is introduced into the main body 11 of the slurry injection device 10, and then agitator, for example an impeller, in the main body 11 By rotating (13), the rare earth magnetic powder slurry (5) is injected through the slurry inlet (15) of the main body (11) toward a mold, for example, a mold of a nonmagnetic material such as sus. Therefore, the rare earth magnetic powder slurry 5 is filled in the inner space formed by the side wall portion 21 and the lower punch 23 of the mold 20.

 After the rare earth magnetic powder slurry 5 is injected into the mold 20 by a predetermined amount for the rare earth sintered magnet, the rare earth magnetic powder slurry 5 is stopped inside the mold 20 by stopping the rotation of the impeller 13. Stop injection into the space.

Subsequently, the upper punch 25 is placed in the upper opening of the mold 20 to pressurize the rare earth magnetic powder slurry 5 in the mold 20 so that the rare earth magnetic powder 1 has a high charge of 2.0 to 4.0 g / cc. The filler 7 filled with density is formed. At this time, the liquid solvent 3 in the filler 7 is partially discharged to the outside of the mold 20. That is, the liquid solvent 3 in the filler 7 is discharged to the outside through the gap between the side wall portion 21 and the lower punch 23 and the gap between the side wall portion 21 and the upper punch 25. . Of course, in order to discharge the liquid solvent 3, a discharge hole (not shown) may be formed through the side wall portion 21.

Next, in the alignment step S40, the mold 20 filled with the filling body 7 is positioned at the center between the left and right magnetic field coil parts 31 of the alignment device. Subsequently, the magnetic field coil part 31 repeatedly applies, for example, a pulse magnetic field of 10 to 80 KOe, preferably a pulse magnetic field of 50 to 70 KOe, for example, 1 to 10 times by the magnetic field coil part 31. The filler (9) in which the rare earth magnetic powder (1) in () is oriented in the magnetic field direction is formed. Therefore, in the filler 9, the oriented rare earth magnetic powder 1a is present. On the other hand, after the alignment step (S40), a separate molding process for increasing the density of the filler (9) does not proceed.

Then, in the extraction step (S50), for example, by using the extraction unit of the extraction device, for example, the air cylinder 31, by moving the lower punch 23 along the guide portion on the inner wall of the side wall portion 21 The filler body 9 is extracted. Thus, the filler body 9 is separated from the mold 20.

Then, in the sintering step (S60), after charging the filler (9) in the sintering furnace (not shown), the filler (9), for example, 1 to 2 at a vacuum atmosphere and 300 ~ 400 ℃ temperature Heating for a time to completely remove the remaining liquid solvent in the filler (9). Subsequently, the filler 9 is heated at a temperature of, for example, a vacuum atmosphere and 1000 to 1100 ° C. for 1 to 4 hours, thereby forming a sintered body and densifying.

Finally, in the heat treatment step (S70), by heating the sintered body, for example, at a temperature of 400 ~ 900 ℃ with a vacuum atmosphere to obtain a rare earth sintered magnet to complete the manufacturing process for the rare earth sintered magnet manufacturing method.

Meanwhile, the magnetic field forming process of forming a molded article by orienting and molding the rare earth magnetic powder in the magnetic field will be described in detail. First, in the process of filling the rare earth magnetic powder in the mold and orienting the rare earth magnetic powder in the mold in the magnetic field, the rare earth magnetic powder It is possible to ensure sufficient space for the rare earth magnetic powder in the mold to be oriented in the magnetic field at a packing density of 40 to 50% of the final compact density, thereby enabling complete magnetic field orientation of the rare earth magnetic powder. On the other hand, in the process of forming the rare earth magnetic powder after the magnetic field orientation of the rare earth magnetic powder, the rare earth magnetic powder of the molded body receives the compressive stress while the volume of the molded body in the mold is reduced. In this process, the initially magnetically oriented rare earth magnetic powder undergoes friction with neighboring rare earth magnetic powder gradually moving toward the center of the molded body, thereby deviating from the initial orientation direction, thereby lowering the orientation ratio.

Therefore, the present invention, in the filling process of the rare earth magnetic powder slurry, by increasing the packing density of the rare earth magnetic powder slurry to a level corresponding to the sintered density of the sintered body, the process does not go through the molding process that occurs most of the orientation misalignment of the rare earth magnetic powder slurry Fillers can be produced. In order to solve the problem that the rare earth magnetic powder is not oriented to the maximum due to the friction between neighboring rare earth magnetic powder due to the high packing density of the initial filler, the rare earth magnetic powder is used by using the rare earth magnetic powder slurry mixed with the rare earth magnetic powder and the liquid solvent. It is possible to maximize the rare earth magnetic powder orientation of the filler by minimizing the friction force between the powders and by using the pulse magnetic field as the applied magnetic field which can generate the strong magnetic field of instantaneous intensity.

Hereinafter, embodiments according to the present invention will be described in detail.

[First Embodiment]

First, in the rare earth magnetic powder production step (S10), to prepare a rare earth magnetic powder (1) for the rare earth sintered magnet.

In more detail, in the mixing step (S11), the alloy composition corresponding to the rare earth magnetic powder (1), for example 32wt% RE-66wt% Fe-1wt% TM-1wt% B (here, RE: rare earth The raw materials of RE, Fe, TM, and B are respectively weighed so as to have an element, TM: 3d transition metal) composition, and these raw materials are mixed. Subsequently, in the dissolution step (S13), these mixed raw materials are melted by a dissolution method, for example, a vacuum induction heating method or the like to form an alloy molten metal. Then, in the quench solidification step (S15), the molten alloy is quench solidified by, for example, strip casting, chilled mold casting or the like to form an alloy ingot. Then, in the hydrotreatment / dehydrogenation step (S17), in order to improve the grinding capacity of the alloy ingot, for example, the alloy ingot is heated for 4 hours at a hydrogen gas atmosphere of 1 atm and a temperature of room temperature to 600 ° C. Hydrogenation treatment. Subsequently, the alloy ingot is heated for 2 hours at a vacuum of ¹ × 10 ⁻¹ Torr or less and at a temperature of 700 ° C. to dehydrogenate the alloy ingot. Then, in the grinding step (S19), by grinding the alloy ingot using a grinding method, for example, a jet mill, a uniform and fine rare earth magnetic powder 1 having an average particle size of about 4.0 µm is obtained, for example. Here, the process of manufacturing the rare earth magnetic powder 1 which has an average particle size of about 4.0 micrometers from an alloy ingot is performed in nitrogen gas or an inert gas atmosphere. This is to prevent the rare earth magnetic powder 1 from being contaminated by oxygen and deteriorating its magnetic properties.

Then, in the slurry forming step (S20), the rare earth magnetic powder (1) 10 to 50wt%, for example, 10wt%, 20wt%, 30wt%, 40wt%, 50wt% of the liquid solvent (3), respectively, Each rare earth magnetic powder slurry 5 is mixed with an organic solvent such as, for example, a nucleic acid or an alcohol. On the other hand, since the liquidity of the rare earth magnetic powder 1 is not improved unless the liquid solvent 3 is included, the rare earth magnetic powder 1 cannot be sufficiently oriented in a subsequent alignment step (S40), and more than 50% of the liquid solvent. If (3) is included, the work to remove a part of the excess liquid solvent (3) before the alignment step (S40) should be added.

Then, in the slurry filling step (S30), the rare earth magnetic powder slurry (5) is introduced into the main body 11 of the slurry injection device 10, and then agitator, for example, an impeller 13 in the main body 11 The rare earth magnetic powder slurry 5 is injected into the mold, for example, a nonmagnetic material such as sus (SUS) through the slurry inlet 15 of the main body 11 by rotating. Therefore, the rare earth magnetic powder slurry 5 is filled in the inner space formed by the side wall portion 21 and the lower punch 23 of the mold 20.

 Then, after the rare earth magnetic powder slurry 5 is injected into the mold 20 by a predetermined amount for the rare earth sintered magnet, the rare earth magnetic powder slurry 5 is stopped by rotating the impeller 13. Stop injection into the internal space of the

Then, the upper punch 25 is placed in the upper opening of the mold 20 to pressurize the rare earth magnetic powder slurry 5 in the mold 20 so that the rare earth magnetic powder 1 is, for example, 3.4 g / cc. The filler 7 filled with high charge density is formed. At this time, the liquid solvent 3 in the filler 7 is discharged to the outside of the mold 20. That is, the liquid solvent 3 in the filler 7 is discharged to the outside through the gap between the side wall portion 21 and the lower punch 23 and the gap between the side wall portion 21 and the upper punch 25. . Of course, in order to discharge the liquid solvent 3, a discharge hole (not shown) may be formed through the side wall portion 21.

Next, in the alignment step S40, the mold 20 filled with the filling body 7 is positioned at the center between the left and right magnetic field coil parts 31 of the alignment device. Subsequently, a pulse magnetic field of 50 KOe, for example, is applied to the filling body 7 by the magnetic field coil part 31 to form the filling body 9 in which the rare earth magnetic powder 1 in the filling body 7 is oriented in the magnetic field direction. do. At this time, in order to increase the orientation ratio of the rare earth magnetic powder 1, the pulse magnetic field may be repeatedly applied one or more times, for example, five times. Therefore, in the filler 9, the oriented rare earth magnetic powder 1a is present. On the other hand, after the alignment step (S40), a separate molding process for increasing the density of the filler (9) does not proceed.

Then, in the extraction step (S50), for example, by using the extraction unit of the extraction device, for example, the air cylinder 31, by moving the lower punch 23 along the guide portion on the inner wall of the side wall portion 21 The filler body 9 is extracted. Thus, the filler body 9 is separated from the mold 20.

Then, in the sintering step (S60), the filler 9 is charged to a sintering furnace (not shown), and then the filler 9 is heated, for example, in a vacuum atmosphere and at 350 ° C. for 2 hours. The remaining liquid solvent in the filler 9 is completely removed. Subsequently, the filler 9 is heated at, for example, a vacuum atmosphere and a temperature of 1070 ° C. for 4 hours to form a sintered body and to densify it.

Finally, in the heat treatment step (S70), for example, by heating the sintered body for 2 hours in a vacuum atmosphere and the temperature of 500 ℃ to obtain a rare earth sintered magnet to complete the manufacturing process for the rare earth sintered magnet manufacturing method.

Subsequently, using a B-H loop tracer, the magnetic hysteresis curve was measured while applying a magnetic field of up to 20 KOe to each rare earth sintered magnet, and the results are shown in Table 1 below.

In Table 1, the rare earth sintered magnet has a high maximum magnetic energy of 44.86 ~ 46.60 MGOe depending on the solvent concentration. When the solvent concentration of the liquid solvent is 30% or more, the characteristics of the rare earth sintered magnet gradually become worse. Therefore, it can be seen that the magnetic properties of the rare earth sintered magnet of the present invention is excellent.

Molding technology Solvent concentration
(wt%) Residual magnetic flux density
(kG) Coercivity
(kOe) Maximum magnetic energy
(MGOe) Pulse magnetic field wet molding technology 10 13.6 16.11 44.85 20 13.7 16.00 46.08 30 13.9 16.02 46.92 40 13.8 15.89 46.54 50 13.8 15.90 46.60

[Second Embodiment]

First, in the rare earth magnetic powder production step (S10), using the same method as mentioned above to prepare a rare earth magnetic powder (1).

Thereafter, in the slurry forming step (S20), the rare earth magnetic powder (1) is mixed with an organic solvent such as a liquid solvent (3) having a concentration of 30 wt%, for example, a nucleic acid or an alcohol, and the like. Form.

Then, in the slurry filling step (S30), the rare earth magnetic powder slurry (5) is introduced into the main body 11 of the slurry injection device 10, and then agitator, for example, an impeller 13 in the main body 11 The rare earth magnetic powder slurry 5 is injected into the mold, for example, a nonmagnetic material such as sus (SUS) through the slurry inlet 15 of the main body 11 by rotating. Therefore, the rare earth magnetic powder slurry 5 is filled in the inner space formed by the side wall portion 21 and the lower punch 23 of the mold 20.

 Then, after the rare earth magnetic powder slurry 5 is injected into the mold 20 by a predetermined amount for the rare earth sintered magnet, the rare earth magnetic powder slurry 5 is stopped by rotating the impeller 13. Stop injection into the internal space of the

Then, the upper punch 25 is placed in the upper opening of the mold 20 to pressurize the rare earth magnetic powder slurry 5 in the mold 20 so as to press the rare earth magnetic powder 1 into the rare earth magnetic powder 1. The fillers 7 respectively filled with high filling densities of 2.6 to 4.0 g / cc, for example, high filling densities of 2.6, 3.0, 3.4, 3.7 and 4.0 g / cc, for enhancing the orientation ratio are formed. At this time, the liquid solvent 3 in the filler 7 is discharged to the outside of the mold 20. That is, the liquid solvent 3 in the filler 7 is discharged to the outside through the gap between the side wall portion 21 and the lower punch 23 and the gap between the side wall portion 21 and the upper punch 25. . Of course, in order to discharge the liquid solvent 3, a discharge hole (not shown) may be formed through the side wall portion 21.

Next, in the alignment step S40, the mold 20 filled with the filling body 7 is positioned at the center between the left and right magnetic field coil parts 31 of the alignment device. Subsequently, a pulse magnetic field of 50 KOe, for example, is applied to the filling body 7 by the magnetic field coil part 31 to form the filling body 9 in which the rare earth magnetic powder 1 in the filling body 7 is oriented in the magnetic field direction. do. At this time, in order to increase the orientation ratio of the rare earth magnetic powder 1, the pulse magnetic field may be repeatedly applied once or plural times, for example, five times. Therefore, in the filler 9, the oriented rare earth magnetic powder 1a is present. On the other hand, after the alignment step (S40), a separate molding process for increasing the density of the filler (9) does not proceed.

Then, in the extraction step (S50), for example, by using the extraction unit of the extraction device, for example, the air cylinder 31, by moving the lower punch 23 along the guide portion on the inner wall of the side wall portion 21 The filler body 9 is extracted. Thus, the filler body 9 is separated from the mold 20.

Then, in the sintering step (S60), the filler 9 is charged to a sintering furnace (not shown), and then the filler 9 is heated, for example, in a vacuum atmosphere and at 350 ° C. for 2 hours. The remaining liquid solvent in the filler 9 is completely removed. Subsequently, the filler 9 is heated at, for example, a vacuum atmosphere and a temperature of 1070 ° C. for 4 hours to form a sintered body and to densify it.

Finally, in the heat treatment step (S70), for example, by heating the sintered body for 2 hours in a vacuum atmosphere and the temperature of 500 ℃ to obtain a rare earth sintered magnet to complete the manufacturing process for the rare earth sintered magnet manufacturing method.

Subsequently, using a B-H loop tracer, the magnetic history curve was measured while applying a maximum magnetic field of 20 KOe to each rare earth sintered magnet, and the results are shown in Table 2.

In Table 2, the rare earth sintered magnet has a high maximum magnetic energy product of 0.94 to 46.92 MGOe depending on the respective packing densities. The characteristics of the rare earth sintered magnet when the packing density is 3.4 g / cc are optimal, and the characteristics of the rare earth sintered magnet when the packing density exceeds 3.4 g / cc or the packing density is smaller than 3.4 g / cc gradually become worse. Therefore, it can be seen that the magnetic properties of the rare earth sintered magnet of the present invention is excellent.

Molding technology Packing density
(g / cc) Residual magnetic flux density
(kG) Coercivity
(kOe) Maximum magnetic energy
(MGOe) Pulse magnetic field wet molding technology 2.6 13.5 15.70 44.55 3.0 13.8 15.88 46.42 3.4 13.9 16.02 46.92 3.7 13.6 16.11 46.07 4.0 13.0 16.24 40.94

[Third Embodiment]

First, in the rare earth magnetic powder production step (S10), using the same method as mentioned above to prepare a rare earth magnetic powder (1).

Thereafter, in the slurry forming step (S20), the rare earth magnetic powder (1) is mixed with an organic solvent such as a liquid solvent (3) having a concentration of 30 wt%, for example, a nucleic acid or an alcohol, and the like. Form.

Then, in the slurry filling step (S30), the rare earth magnetic powder slurry (5) is introduced into the main body 11 of the slurry injection device 10, and then agitator, for example, an impeller 13 in the main body 11 The rare earth magnetic powder slurry 5 is injected into the mold, for example, a nonmagnetic material such as sus (SUS) through the slurry inlet 15 of the main body 11 by rotating. Therefore, the rare earth magnetic powder slurry 5 is filled in the inner space formed by the side wall portion 21 and the lower punch 23 of the mold 20.

 Then, after the rare earth magnetic powder slurry 5 is injected into the mold 20 by a predetermined amount for the rare earth sintered magnet, the rare earth magnetic powder slurry 5 is stopped by rotating the impeller 13. Stop injection into the internal space of the

Then, the upper punch 25 is placed in the upper opening of the mold 20 to pressurize the rare earth magnetic powder slurry 5 in the mold 20 so that the rare earth magnetic powder 1 has a high filling density of 3.4 g / cc. The filler 7 filled with is formed. At this time, the liquid solvent 3 in the filler 7 is discharged to the outside of the mold 20. That is, the liquid solvent 3 in the filler 7 is discharged to the outside through the gap between the side wall portion 21 and the lower punch 23 and the gap between the side wall portion 21 and the upper punch 25. . Of course, in order to discharge the liquid solvent 3, a discharge hole (not shown) may be formed through the side wall portion 21.

Next, in the alignment step S40, the mold 20 filled with the filling body 7 is positioned at the center between the left and right magnetic field coil parts 31 of the alignment device. Subsequently, the magnetic field coil part 31 applies a pulse magnetic field of, for example, 10 to 50 KOe, for example, 10 KOe, 20 KOe, 30 KOe, 40 KOe, 50 KOe, to the filler 7 to form a rare earth magnetic powder in the filler 7. The filler 9 in which (1) was oriented in the magnetic field direction is formed, respectively. At this time, in order to increase the orientation ratio of the rare earth magnetic powder 1, the pulse magnetic field may be repeatedly applied once or plural times, for example, five times. Therefore, in the filler 9, the oriented rare earth magnetic powder 1a is present. On the other hand, after the alignment step (S40), a separate molding process for increasing the density of the filler (9) does not proceed.

Then, in the extraction step (S50), for example, by using the extraction unit of the extraction device, for example, the air cylinder 31, by moving the lower punch 23 along the guide portion on the inner wall of the side wall portion 21 The filler body 9 is extracted. Thus, the filler body 9 is separated from the mold 20.

Then, in the sintering step (S60), the filler 9 is charged to a sintering furnace (not shown), and then the filler 9 is heated, for example, in a vacuum atmosphere and at 350 ° C. for 2 hours. The remaining liquid solvent in the filler 9 is completely removed. Subsequently, the filler 9 is heated at, for example, a vacuum atmosphere and a temperature of 1070 ° C. for 4 hours to form a sintered body and to densify it.

Finally, in the heat treatment step (S70), for example, by heating the sintered body for 2 hours in a vacuum atmosphere and the temperature of 500 ℃ to obtain a rare earth sintered magnet to complete the manufacturing process for the rare earth sintered magnet manufacturing method.

Subsequently, using a B-H loop tracer, the magnetic history curve was measured while applying a maximum magnetic field of 20 KOe to each rare earth sintered magnet, and the results are shown in Table 3.

In Table 3, the rare earth sintered magnet has a high maximum magnetic energy of 40.94-46.92 MGOe depending on the applied pulse magnetic field strength. The characteristics of the rare earth sintered magnets when the pulse magnetic field strength is less than 10 kOe are not improved compared to the prior art, and when the pulse magnetic field strength is larger than 80 kOe, the capacity of the power supply device must be larger and the economic difficulty There is this. Therefore, it can be seen that the magnetic properties of the rare earth sintered magnet of the present invention is excellent.

Molding technology Pulse field strength
(kOe) Residual magnetic flux density
(kG) Coercivity
(kOe) Maximum magnetic energy
(MGOe) Pulse magnetic field wet molding technology 10 13.1 16.31 41.12 20 13.4 16.27 43.77 30 13.6 16.28 46.11 40 13.8 16.11 46.45 50 13.9 16.02 46.92

[Comparative Example]

First, in the rare earth magnetic powder production step (S10), using the same method as mentioned above to prepare a rare earth magnetic powder (1).

Thereafter, using the conventional static magnetic field transverse shaping technology, the rare earth magnetic powder 1 is filled into a mold (not shown) at a packing density of 1.8, 2.0, 2.2, 2.5, and 2.8 g / cc, respectively, using an electromagnet. Then, a powder (or not shown) is formed by powder orientation and molding while applying a static magnetic field of 20 KOe for 5 seconds to each rare earth magnetic powder in the mold.

Then, after the molded body is charged into a sintering furnace (not shown), the molded body is sintered and densified for 4 hours at, for example, a vacuum atmosphere and a temperature of 1070 ° C to form a sintered body. Finally, the rare earth sintered magnet is manufactured by heat-treating the sintered body at a temperature of about 500 ° C., for example.

Subsequently, magnetic history curves were measured using a B-H loop tracer while applying a maximum magnetic field of 20 KOe to each rare earth sintered magnet, and the results are shown in Table 4.

In Table 4, the rare earth sintered magnets produced by the prior art have a low maximum magnetic energy product of 45 MGOe depending on the respective packing densities. Therefore, it can be seen that the conventional rare earth sintered magnet exhibits lower magnetic properties than the rare earth sintered magnet of the present invention.

Molding technology Packing density
(g / cc) Residual magnetic flux density
(kG) Coercivity
(kOe) Maximum magnetic energy
(MGOe) Static magnetic field transverse molding technology 1.8 13.4 16.08 43.89 2.0 13.5 16.22 44.10 2.2 13.5 16.20 44.15 2.5 13.3 16.28 43.51 2.8 13.1 16.41 41.08

On the other hand, as described above, the present invention described the features and technical advantages of the present invention with reference to the preferred embodiments in order to better understand the claims of the present invention described below, changes, modifications of the present invention The modifications may be made by a person skilled in the art without departing from the spirit or scope of the invention as defined only by the claims.

1: rare earth magnetic powder
1a: Oriented rare earth magnetic powder
3: liquid solvent
5: rare type magnetic powder slurry
7,9: filler
10: slurry injection device
11: body
13: impeller
15: slurry inlet
20: mold
21: side wall
23: lower punch
25: upper punch
31: Magnetic coil part

Claims (5)

Preparing a rare earth magnetic powder for the rare earth sintered magnet;
Mixing the rare earth magnetic powder with a liquid solvent to form a rare earth magnetic powder slurry;
After filling the rare earth magnetic powder slurry to a mold, by pressing the rare earth magnetic powder slurry by a punch to discharge the liquid solvent of the rare earth magnetic powder slurry to the outside of the mold to form a filler of the rare earth magnetic powder, The rare earth magnetic powder has a filling density for increasing the orientation ratio of the rare earth magnetic powder;
Applying a magnetic pulse to the filler in the mold by using a magnetic coil to orient the rare earth magnetic powder of the filler, and applying the pulse magnetic field one or more times to increase the orientation ratio of the rare earth magnetic powder;
Separating the filler from the mold; And
Rare earth sintered magnet manufacturing method comprising the step of sintering the filler.
The method of claim 1, wherein the forming of the filler comprises:
Filling the rare earth magnetic powder slurry into a mold by using a slurry injection device;
Disposing an upper punch on an upper side of the mold; And
And pressing the rare earth magnetic powder slurry by the upper punch and the lower punch of the mold to discharge the liquid solvent of the rare earth magnetic powder slurry to form the filler. .
The rare earth sintered magnet production method according to claim 1, wherein the rare earth magnetic powder is mixed with a liquid solvent having a concentration of 10 to 50 wt%.
The rare earth sintered magnet production method according to claim 1, wherein the rare earth magnetic powder is filled at a packing density of 2.0 to 4.0 g / cc.
The rare earth sintered magnet manufacturing method according to claim 1, wherein the pulse magnetic field is applied one or more times in the range of 10 to 80 KOe.

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