KR102435666B1 - Method for manufacturing rare earth permanent magnet and rare earth permanent magnet manufactured therefrom - Google Patents

Abstract

The present invention relates to a method for manufacturing a rare earth permanent magnet and a rare earth permanent magnet manufactured thereby. The method for manufacturing a rare earth permanent magnet of the present invention comprises the steps of: manufacturing a rare earth magnet sintered body which includes an RE-Fe-B-TM system composition, wherein RE is 26 to 31 wt%, B is 0.5 to 1.5 wt%, TM is 0 to 15 wt%, and Fe is the remainder; processing the rare earth magnet sintered body into a predetermined shape; treating a surface of the processed rare earth magnet sintered body with a coating material containing at least one of rare earth metal and a rare earth metal compound in an amount of 0.4 to 1.2 wt% with respect to the weight of the processed rare earth magnet sintered body; loading the processed rare earth magnet sintered body into a furnace and primarily heating the same at a temperature of 800 to 1,000 ℃ for 4 to 8 hours in a vacuum or inert gas atmosphere to diffuse the coating material into the rare earth magnet sintered body; and secondarily heating the material obtained through the primarily heating step at a temperature of 400 to 600 ℃ in a vacuum or inert gas atmosphere.

Description

Method for manufacturing rare earth permanent magnet and rare earth permanent magnet manufactured therefrom

The present invention relates to a method for manufacturing a rare earth permanent magnet and to a rare earth permanent magnet manufactured by the method.

The most important information recording device of a computer, the hard disk drive (HDD), was the most important issue with the expansion of portable computers such as laptops a few years ago, while the miniaturization of the device was the most important issue. And it is changing with high speed. This trend change is due to an increase in the demand for computers used in the construction of various big data servers as the modern industrial structure enters the information society in earnest, and as the utilization of numerous data information and real-time communication become essential requirements. Therefore, unlike a moving personal desktop or notebook computer, server computers are used in a fixed location, so it is understood that it is most reasonable to increase the capacity of information storage and speed up the processing speed of these large amounts of information rather than reducing the size of the device.

Among these computer trend changes, the speeding up of the information processing speed increases the linear reciprocating speed of an actuator called Voice Coil Motor (VCM) that moves the MR or GMR sensor that reads and writes magnetic records at high speed among the components constituting the HDD. In order to increase the VCM speed, it is essential to maximize the magnetic flux density formed in the gap between two rare-earth magnets arranged in opposite directions among the components constituting the VCM.

On the other hand, the main magnetic properties for evaluating the performance of rare-earth magnets used in VCM are residual magnetic flux density and coercive force. In order to increase the magnitude of the magnetic flux density formed by the rare-earth magnets radiating to the outside, the residual magnetic flux density is generally increased. This method has been known to be the most reasonable means. When the residual magnetic flux density of a rare earth magnet is increased to a certain level, the magnetic flux density formed on the magnet surface also tends to be linearly proportional to the residual magnetic flux density increase.

On the other hand, the residual magnetic flux density and coercive force form a trade-off relationship due to the composition of the elements constituting the rare earth magnet and the nature of the manufacturing process. When it is increased, the coercive force (kOe) decreases to form an intersection point where the residual magnetic flux density and the coercive force are equal. If the residual magnetic flux density is increased beyond that, a magnet is manufactured in which the residual magnetic flux density (kG) is greater than the coercive force (kOe). In such a characteristic range, there is a problem that the increase in the residual magnetic flux density is not guaranteed to be proportional to the increase in the magnetic flux density formed on the surface of the magnet.

Specifically, the rare earth magnet used in a motor or actuator constitutes an open magnetic circuit in which a gap between the magnet and other materials is formed. An anti-magnetic field is formed toward the inside of the magnet, and this anti-magnetic field serves to demagnetize the magnetized magnet, and its magnitude is proportional to the residual magnetic flux density. In particular, in the case of VCM, a very large anti-magnetic field is formed because the gap between the two opposing rare-earth magnets is relatively large.

Japanese Laid-Open Patent Publication No. 2006-041295

The present invention was devised in consideration of the above points, and a rare earth material capable of forming a high magnetic flux density on the surface of a magnet despite the formation of a large anti-magnetic field that may occur when an open magnetic circuit is formed with a rare earth permanent magnet. An object of the present invention is to provide a method for manufacturing a permanent magnet and a rare-earth permanent magnet manufactured through the same.

In addition, the present invention provides a rare-earth magnet for VCM capable of achieving an increase in VCM speed and high-speed HDD by providing the rare-earth permanent magnet according to the present invention as a rare-earth magnet employed in a VCM of a hard disk, and a hard disk drive including the same. It serves a different purpose to provide.

In order to solve the above problems, the present invention provides a step of manufacturing a rare earth magnet sintered body having a RE-Fe-B-TM system (here, RE = rare earth element, TM = 3d transition element) composition and having a rare earth element content of 31 wt% or less; processing the rare-earth magnet sintered body into a predetermined shape; treating the surface of the processed rare-earth magnet sintered body so that an applied material including at least one of a rare earth metal and a rare earth metal compound is disposed; The first heat treatment step in which the coated material is diffused into the rare earth magnet sintered body by charging the sintered body into the furnace and heating it to a temperature of 400 to 1,000°C in a vacuum or inert gas atmosphere, and 400 to 1000°C in a vacuum or inert gas atmosphere after the first heat treatment Provided is a method for manufacturing a rare earth permanent magnet, which includes the step of performing secondary heat treatment at a temperature.

According to an embodiment of the present invention, the heat treatment temperature in the first heat treatment step may be greater than the heat treatment temperature in the second heat treatment step.

Further, in the composition of the rare earth magnet sintered body, RE is 26 to 31% by weight, B is 0.5 to 1.5% by weight, and TM is 0 to 15% by weight, and Fe may be contained in the balance.

In addition, the total weight of any one or more of the rare earth metal and the rare earth metal compound may be treated to be 0.1 to 2.0 wt %, more preferably 0.25 to 2.0 wt %, more preferably 0.1 to 2.0 wt % based on the weight of the magnet to which the coating material is treated It can be treated to be 0.4 to 1.2 wt%.

In addition, the rare earth metal and the rare earth metal compound include at least one light rare earth metal selected from the group consisting of lanthanum, cerium, praseodymium, promethium, neodymium, samarium, europium, and scandium, and gadolinium, terbium, dysprosium, holm, erbium, thulium, and ytterbium. , may include one or more of one or more heavy rare earth metals selected from the group consisting of lutetium and yttrium.

In addition, the present invention is a rare earth permanent magnet magnet having a RE-Fe-B-TM system (here, RE = rare earth element, TM = 3d transition element) composition, the rare earth element content is 33 wt% or less, and the residual magnetic flux density is 14.20 kG or more provides

According to an embodiment of the present invention, the residual magnetic flux density (kG) may be smaller than the coercive force (kOe).

In addition, it may be used for VCM provided in a hard disk drive.

In addition, the rare earth permanent magnet may be manufactured by the manufacturing method according to the present invention.

In addition, the present invention provides a hard disk drive including the rare earth permanent magnet according to the present invention.

The method for manufacturing a rare-earth permanent magnet according to the present invention can form a high magnetic flux density on the surface of the magnet despite the formation of a large anti-magnetic field that can occur when an open magnetic circuit is formed with the rare-earth permanent magnet. In addition, due to these physical properties, it is very suitable as a rare earth magnet used in the VCM of a hard disk drive, and is useful for increasing the speed of the VCM and achieving the high speed of the HDD, so it can be widely applied to various hard disk drives and related industries. have.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily implement them. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

A rare-earth permanent magnet according to an embodiment of the present invention has a RE-Fe-B-TM system (here, RE = rare earth element, TM = 3d transition element) composition and a rare earth element content of 31 wt% or less for manufacturing a rare earth magnet sintered body Step (step S1), processing the rare-earth magnet sintered body into a predetermined shape (step S2), processing the coating material including at least one of a rare-earth metal and a rare-earth metal compound to be disposed on the surface of the processed rare-earth magnet sintered body (step S2) Step S3), the first heat treatment step of charging the processed rare-earth magnet sintered body having the coating material on the surface into the furnace and heating it in a vacuum or inert gas atmosphere to a temperature of 400 ~ 1,000℃ to diffuse the coating material into the rare earth magnet sintered body (S4) step), and after the first heat treatment, in a vacuum or inert gas atmosphere, the second heat treatment at a temperature of 400 to 1000° C. (step S5) may be prepared.

First, as the step S1 according to the present invention, a step of manufacturing a rare earth magnet sintered body having a RE-Fe-B-TM system (here, RE = rare earth element, TM = 3d transition element) composition and having a rare earth element content of 31 wt% or less was performed. carry out

The rare earth magnet sintered body may be manufactured by a known method using an alloy powder having a RE-Fe-B-TM-based composition. For example, the rare earth magnet sintered body may be manufactured by compression molding and sintering powder having a desired alloy composition.

Specifically, the powder having the alloy composition is uniformly melted by induction heating in an inert gas atmosphere, for example, an arcon atmosphere, in a base material weighed to have a desired alloy composition, and a mold casting or strip casting method can be prepared, and a strip According to the casting method, it may be pulverized after realizing an alloy strip by cooling at a cooling rate of 0.1 to 5 m/s. In addition, in order to improve the pulverization ability before pulverization, hydrogen absorption and removal is normally exposed for a long time at room temperature and hydrogen atmosphere so that hydrogen is sufficiently absorbed in the alloy strip. The crack-inducing alloy scrip may be finely powdered using a known grinding technique, for example, a jet-mill, and the embodied alloy powder may have an average particle diameter of 1.0 to 5.0 μm.

The alloy powder has a RE-Fe-B-TM composition, specifically, RE is 26 to 31 wt%, B is 0.5 to 1.5 wt%, TM is 0 to 15 wt%, and Fe may be contained in the balance. Here, RE is a rare earth element, and one or two or more selected from Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu may be used. . For example, the RE may be Nd in consideration of cost and magnetic properties. RE in the raw alloy is contained in an amount of 31% by weight or less, preferably 26 to 31% by weight. If it exceeds 31% by weight, the magnetic flux density formed on the surface of the implemented rare earth permanent magnet can achieve the object of the present invention. It may not be large enough to the level that is present, and the surface magnetic flux density of the final magnet may decrease.

In addition, the TM may be, for example, Co or Ni as a 3d transition element. The TM may include the purpose of increasing the Curie temperature, but may cause deterioration of magnetic properties such as a decrease in residual magnetic flux density. Accordingly, for example, the TM may be contained within 15% by weight when not included in the raw alloy or included in the raw alloy.

In addition, B may be contained in an amount of 0.5 to 1.5% by weight of the raw alloy.

In addition, the raw material alloy contains one or two or more elements among Ti, Al, V, Nb, Ga, Zr, Cu, Si, Cr, Mn, Zn, Mo, Hf, W, Ta and Sn within 2% by weight. It may further contain, and by containing these elements, magnetic properties such as residual magnetic flux density and coercive force can be improved.

In addition, the Fe may be contained in the remaining amount in the raw material alloy.

The obtained rare-earth alloy powder can be compression-molded after being charged into a predetermined mold. In addition, a magnetic field is applied during compression molding to obtain a compression molded article oriented in the magnetic field direction. The compression molded body may be charged into a sintering furnace to be manufactured into a sintered body and sintered at a temperature of 900 to 1100°C. In addition, sintering may be performed in a vacuum atmosphere, for example, after heating at a low temperature increase rate to 400 ° C., completely removing residues such as solvents, and then raising the temperature to 900 to 1100 ° C. at a rate of 3 to 10 ° C./min. After holding for 3 hours, it can be cooled and implemented as a rare earth magnet sintered body.

The embodied rare-earth magnet sintered body is subjected to a step of processing the rare earth magnet sintered body into a predetermined shape as step S2 according to the present invention.

The predetermined shape may be, for example, a VCM shape, and may be subjected to processing such as grinding and cutting to achieve a desired size, and the grinding and cutting may be performed using a known technique in the art, so the present invention is particularly concerned with this. do not limit

Thereafter, as step S3 according to the present invention, a treatment step is performed so that a coating material including at least one of a rare earth metal and a rare earth metal compound is disposed on the surface of the processed rare earth magnet sintered body.

Preferably, steps of degreasing, washing, pickling and drying the processed rare-earth magnet sintered body may be further performed before step S3 is performed.

Specifically, through step S3 and step S4 to be described later, the rare earth metal component contained in the coating material penetrates from the surface of the magnet to the inside through diffusion. It is important to keep the surface clean by removing rust from the surface. As an example, after immersing the processed sintered body in an alkaline degreasing agent solution, and rubbing it with a pie 2 ~ 10mm sized ceramic ball to remove the oil component on the surface of the magnet, clean the processed sintered body several times with distilled water. The remaining degreasing agent can be completely removed. As a continuous process, rust generated during processing can be completely removed by immersing the degreased sintered compact in a nitric acid dilute solution with a content of 1 to 10% and pickling for 1 to 5 minutes. Transfer to distilled water and use an ultrasonic cleaner to remove nitric acid remaining on the surface of the sintered body and dry it sufficiently.

The coating material including any one or more of the rare earth metal and the rare earth metal compound may be disposed on the surface of the processed rare earth magnet sintered body that has been subjected to the degreasing, washing, pickling and drying steps as described above.

The coating material including any one or more of the rare earth metal and the rare earth metal compound may further include any one or more of the rare earth metal and the rare earth metal compound, and alcohol as a dispersion medium, which may be included in a weight ratio of 40 to 60: 60 to 40, respectively. and may be included, for example, in a weight ratio of 50:50.

In addition, at least one of the rare earth metal and the rare earth metal compound is selected from the group consisting of lanthanum, cerium, praseodymium, promethium, neodymium, samarium, europium, and scandium, and at least one light rare earth metal selected from the group consisting of, and gadolinium, terbium, dysprosium, holm, erbium , thulium, ytterbium, lutetium, and yttrium may include one or more of one or more heavy rare earth metals selected from the group consisting of. In addition, the compound containing the rare earth metal compound as described above may be a hydrogen compound or a fluorine compound.

In addition, the rare earth metal and the rare earth metal compound may be included in the coating material in the form of a powder. .

On the other hand, the above-described coating material may be treated such that the total weight of at least one of the rare earth metal and the rare earth metal compound is 0.1 to 2.0 wt %, more preferably 0.25 to 1.2 wt %, based on the weight of the magnet to which the coating material is treated. , more preferably 0.4 to 2.0% by weight, more preferably 0.4 to 1.2% by weight, and as a very preferred example, it may be treated to be 0.40 to 0.65% by weight. If the total weight of any one or more of the rare earth metal and the rare earth metal compound in the treated coating material is less than 0.1% by weight based on the weight of the treated magnet, the surface magnetic flux density formed on the surface of the magnet to be realized is low, which may not be sufficient. In addition, the residual magnetic flux density and coercive force implemented when it exceeds 2.0 wt% may be reduced, and the surface magnetic flux density formed on the surface of the magnet may be low. On the other hand, when the total weight of one or more of the rare-earth metal and the rare-earth metal compound exceeds 1.2% by weight, for example, when the total weight of one or more of the rare-earth metal and the rare-earth metal compound exceeds the weight of the magnet to which the coating material is treated, the input amount of one or more of the rare-earth metal and the rare-earth metal compound is increased There is a risk of rising manufacturing costs.

Next, in step S4 according to the present invention, the processed rare-earth magnet sintered body having the coating material on its surface is charged into the furnace and heated to a temperature of 400 to 1,000° C. in a vacuum or inert gas atmosphere to diffuse the coated material into the rare earth magnet sintered body. A first heat treatment step is performed.

Preferably, in the first heat treatment step, the heat treatment temperature may be 800 to 1000° C., and the temperature increase rate to the heat treatment temperature may be 0.5 to 2° C. In addition, it may be carried out under vacuum or an inert gas atmosphere, for example, an argon gas atmosphere. In addition, the holding time at the heat treatment temperature may be 4 to 8 hours, which may be advantageous to achieve the object of the present invention.

In addition, after the first heat treatment step, as step S5 according to the present invention, a step of performing a second heat treatment at a temperature of 400 to 1000° C. in a vacuum or an inert gas atmosphere is performed, thereby improving the diffusivity of the rare earth metal element, and heat treatment It may be advantageous to implement a magnet of good quality without cracks inside and outside the magnet. Preferably, after the first heat treatment step, after being cooled to room temperature at a cooling rate of 10 to 50° C./min, 400 to 1000° C. at a temperature increase rate of 1 to 10° C./min, more preferably, the heat treatment temperature in the first heat treatment step It can be heat treated for 1 to 3 hours at a lower 400 ~ 600 ℃ temperature.

The rare earth permanent magnet implemented by the above-described manufacturing method has a RE-Fe-B-TM system (here, RE = rare earth element, TM = 3d transition element) composition, the rare earth element content is 33 wt% or less, and the residual magnetic flux density is 14.20 more than kg.

In addition, according to an embodiment of the present invention, the residual magnetic flux density (kG) is smaller than the coercive force (kOe) while having a residual magnetic flux density of 14.20 kG or more, so that the surface magnetic flux density is proportional to the increase in the residual magnetic flux density even in an open magnetic circuit. There are advantages to increase. If the residual magnetic flux density is less than 14.20 kG, it may be difficult to use as a VCM employed in a high-speed hard disk drive because the magnetic flux density formed on the surface is low. In addition, if the residual magnetic flux density (kG) is equal to or greater than the coercive force (kOe), the surface magnetic flux density may be low even when the residual magnetic flux density is greater than 14.20 kG.

In addition, the implemented rare earth permanent magnet may have a coercive force of 13.0 kOe or more, more preferably 14.3 kOe or more. In addition, the surface magnetic flux density may be 6000 kG or more, more preferably 6600 kG or more, and still more preferably 6800 kG or more.

The rare-earth permanent magnet according to the present invention described above may be suitable for VCM applications provided in hard disk drives as it exhibits excellent surface magnetic flux density as described above. Accordingly, the present invention includes a hard disk drive including the above-mentioned rare earth permanent magnet, and in the case of other components included in the hard disk drive, any known structure employed in the hard disk drive can be employed without limitation, so the present invention is not limited thereto. is not particularly limited.

The present invention will be described in more detail through the following examples, but the following examples are not intended to limit the scope of the present invention, which should be construed to aid understanding of the present invention.

<Example 1>

30% by weight RE-68% by weight Fe-1% by weight TM-1% by weight B was composed of, at this time, RE was composed of Nd, TM was composed of Co. Each was appropriately weighed to match the content of the composition, the components were mixed and uniformly dissolved by induction heating in an argon atmosphere, and cooled to a cooling condition of 1 m/sec using a strip casting method to prepare an alloy strip. In order to improve the pulverization ability of the manufactured alloy strip, it was exposed to room temperature and hydrogen atmosphere for 6 hours so that hydrogen was sufficiently absorbed in the alloy strip. By removing the hydrogen, sufficient cracks were induced in the alloy strip. Then, the coarse alloy powder was collided between the powder and the powder by high-pressure nitrogen gas using a jet-mill device to prepare a uniform powder having an average particle diameter of 3.5 μm.

The prepared rare-earth alloy powder was charged into a mold and compression molding was performed while applying a magnetic field of 2 Tesla to prepare a compression molded body oriented in the magnetic field direction. After completely removing residues such as solvents remaining in the molded body, the temperature was raised to 1060°C at a temperature increase rate of 5°C/min and maintained for 2 hours, followed by cooling to prepare a rare earth magnet sintered body.

Thereafter, the rare earth magnet sintered body was polished and cut to manufacture a VCM shape and size workpiece.

After that, the workpiece was immersed in an alkali degreasing agent solution to remove foreign substances such as oil and partially rusted surface, and then rubbed with a pie 8-sized ceramic ball to remove oil on the surface of the magnet. , the remaining degreasing agent was completely removed by washing the magnet again several times with distilled water. As a continuous process, rust generated during processing was completely removed by immersing the degreased sintered body in a nitric acid dilute solution with a content of 5% and pickling for 2 minutes. The nitric acid remaining on the magnet surface was removed using a washer and dried sufficiently. After that, the coating material is prepared by mixing and uniformly kneading the Dy-hydrogen compound (DyH ₂ ) so that the ratio of the ethanol and the ethanol is 1:1 by weight. -The hydrogen compound was uniformly applied to the selected both sides of the magnet, and the content of the Dy-hydrogen compound applied to the workpiece, which is a magnet, was adjusted to be 0.1 wt% based on the weight of the workpiece, which is a magnet. After that, the workpiece coated with the coating material is charged into a heating furnace, heated at a temperature increase rate of 1°C/min in an argon gas atmosphere, and maintained at 900°C for 6 hours while the Dy-hydrogen compound is decomposed into Dy and diffused and penetrated into the magnet. The reaction was allowed to proceed. After the diffusion was completed, it was cooled to room temperature, and the temperature was raised again at a temperature increase rate of 1°C/min, and final heat treatment was performed at 500°C for 2 hours. Through the process, rare earth permanent magnets as shown in Table 1 were finally manufactured.

<Examples 2 to 5>

It was prepared in the same manner as in Example 1, but by adjusting the content of the Dy-hydrogen compound applied in the coating material as shown in Table 1 below, rare earth permanent magnets as shown in Table 1 were manufactured.

<Comparative Examples 1 to 2>

Prepared in the same manner as in Example 1, but after changing the weight % of the total rare earth elements in the alloy without treating the coating material or without treating the coating material as shown in Table 1 below, a final heat treatment at 500 ° C. for 2 hours Rare-earth permanent magnets as shown in Table 1 were prepared.

<Experimental example>

For the rare earth permanent magnets manufactured in Examples and Comparative Examples, each loop was measured while applying a maximum magnetic field of 30 kOe using a B-H loop tracer. Also, the magnet was assembled into a VCM module and a Gauss meter was used in the gap between the two magnets. The surface magnetic flux density was measured and shown in Table 1 below.

gun in alloy
rare earth elements
(weight%) grain boundary
diffusion
Whether in the coating material
rare earth metal elements
Application amount (wt%) residual
magnetic flux density,
Br(kG) coercive force,
hcj
(kOe) surface magnetic flux density,
φ(kG) Example 1 30 ○ 0.1 14.69 13.2 6211 Example 2 30 ○ 0.25 14.67 14.3 6544 Example 3 30 ○ 0.5 14.65 14.9 6830 Example 4 30 ○ 0.75 14.62 15.5 6816 Example 5 30 ○ 1.0 14.60 15.8 6821 Example 6 30 ○ 0.05 14.70 12.5 5820 Example 7 30 ○ 1.2 14.58 16.0 6800 Example 8 30 ○ 2.0 14.50 15.8 6751 Example 9 30 ○ 2.2 14.47 15.4 6661 Comparative Example 1 30 × × 14.70 12.0 5574 Comparative Example 2 32 × × 13.41 15.1 6240

As can be seen from Table 1,

In Comparative Examples 1 and 2, it can be seen that the surface magnetic flux density is lower than in Examples. In addition, in the case of Comparative Example 2, the surface magnetic flux density was higher than that of Example 1, which was due to the low residual magnetic flux density but large coercive force.

In addition, it can be seen that Examples 3 to 9 having a residual magnetic flux density of 14.2 kG or more and having a smaller residual magnetic flux density than a coercive force have very excellent surface magnetic flux density compared to other Examples.

Although one embodiment of the present invention has been described above, the spirit of the present invention is not limited to the embodiments presented herein, and those skilled in the art who understand the spirit of the present invention can add components within the scope of the same spirit. , changes, deletions, additions, etc. may easily suggest other embodiments, but this will also fall within the scope of the present invention.

Claims (10)

RE-Fe-B-TM system (here, RE = rare earth element, TM = 3d transition element) composition, RE is 26 to 31 wt%, B is 0.5 to 1.5 wt%, TM is 0 to 15 wt%, manufacturing a rare-earth magnet sintered body containing Fe as the balance;
processing the rare earth magnet sintered body into a predetermined shape;
treating the surface of the processed rare earth magnet sintered body with a coating material including at least one of a rare earth metal and a rare earth metal compound in an amount of 0.4 to 1.2 wt% based on the weight of the processed rare earth magnet sintered body;
A first heat treatment step of charging the processed rare-earth magnet sintered body having the coating material on its surface into a furnace and heating it in a vacuum or inert gas atmosphere at a temperature of 800 to 1,000° C. for 4 to 8 hours to diffuse the coated material into the rare earth magnet sintered body; and
After the primary heat treatment, performing a second heat treatment at a temperature of 400 to 600° C. in a vacuum or in an inert gas atmosphere to prepare a rare earth permanent magnet, wherein the rare earth permanent magnet has a rare earth element RE content of 26.4 to 32.2 wt%; , A method for manufacturing a rare earth permanent magnet having a residual magnetic flux density of 14.58 kG or more and less than 14.67 kG, a coercive force (kOe) greater than the residual magnetic flux density (kG), and a surface magnetic flux density of 6800 to 6830 kG. delete delete delete According to claim 1,
The rare earth metal and the rare earth metal compound include at least one light rare earth metal selected from the group consisting of lanthanum, cerium, praseodymium, promethium, neodymium, samarium, europium, and scandium, and
A method for manufacturing a rare earth permanent magnet comprising at least one selected from the group consisting of gadolinium, terbium, dysprosium, holm, erbium, thulium, ytterbium, lutetium and yttrium. It has a RE-Fe-B-TM system (here, RE = rare earth element, TM = 3d transition element) composition, the rare earth element content is 26.4 ~ 32.2 wt%, the residual magnetic flux density is 14.58 kG or more and less than 14.67 kG, and the coercive force (kOe) ) is greater than the residual magnetic flux density (kG) and the surface magnetic flux density is 6800 ~ 6830 kG of rare earth permanent magnets. delete 7. The method of claim 6,
A rare-earth permanent magnet, characterized in that it is used for VCM provided in a hard disk drive. 7. The method of claim 6,
A rare earth permanent magnet manufactured by the manufacturing method according to claim 1 . 10. A hard disk drive comprising the rare earth permanent magnet according to any one of claims 6, 8 and 9.