KR102236096B1 - Method for manufacturing ceramic bonded magnet and ceramic bonded magnet manufactured therefrom - Google Patents

Abstract

The present invention relates to a method for manufacturing a ceramic bonded magnet, and more particularly, to a method for manufacturing a ceramic bonded magnet that can be used in a high temperature environment of 200℃ or higher, and a ceramic bonded magnet manufactured therefrom. The present invention includes steps of preparing a magnetic powder and preparing a mixed powder.

Description

Method for manufacturing ceramic bonded magnet and ceramic bonded magnet manufactured therefrom {Method for manufacturing ceramic bonded magnet and ceramic bonded magnet manufactured therefrom}

The present invention relates to a method of manufacturing a ceramic bonded magnet, and more particularly, to a method of manufacturing a ceramic bonded magnet usable in a high temperature environment of 200°C or higher, and a ceramic bonded magnet manufactured through the same.

Rare-earth bonded permanent magnets are advantageous in miniaturization and weight reduction of motors as they can improve their magnetic force by 3 to 5 times compared to conventional ferrite magnets.

Rare-earth bonded magnets are manufactured by mixing a rare-earth magnetic powder and a bonding resin such as an organic binder, and press-molding into a desired magnet shape. Specifically, compression molding, injection molding, and extrusion molding are used. The compression molding method is a method of manufacturing a magnet by filling the compound in a press mold and then compression molding it to obtain a molded body, followed by heating to cure a thermosetting resin, which is a bonding resin. Compared to other methods, this method is widely used in preparation for the low degree of freedom for the implemented magnet shape because at least the amount of the binding resin can be molded.

However, in the case of a bonded magnet manufactured using a bonding resin such as an organic binder, when used in a high temperature environment of 200°C or higher, the bonding resin contained may be melted or thermally decomposed, and thus there is a problem that its use is limited.

Japanese Published Patent Publication No. 2004-072005

The present invention was conceived in consideration of the above points, and an object of the present invention is to provide a ceramic bonded magnet manufacturing method in which a decrease in mechanical strength at a high temperature compared to that at room temperature is minimized or prevented, and a ceramic bonded magnet manufactured through the method. have.

In addition, another object of the present invention is to provide a ceramic bonded magnet manufacturing method capable of minimizing fluctuations in magnetic properties such as reduction of coercivity due to improvement in mechanical strength at high temperature, and a ceramic bond manufactured through the same.

In order to solve the above problems, the present invention is a RE-Fe-B-TM system (here, RE = rare earth element, TM = 3d transition element) composition, step S1 of preparing a magnetic powder containing crystal grains, the magnetic powder It provides a method for manufacturing a ceramic bonded magnet manufactured including step S2 of preparing a mixed powder by kneading ceramic powder having a melting point of 400° C. or less and step S3 of hot compression molding the mixed powder.

According to an embodiment of the present invention, the magnetic powder may be an isotropic magnetic powder having an average particle diameter of 50 to 300 μm.

In addition, the isotropic magnetic powder may be prepared by HDDR or melt-spinning method.

In addition, in the above composition, RE may be 28 to 35 at%, B may be 0.5 to 1.5 at%, and TM may be 0 to 15 at%.

In addition, the ceramic powder may be V ₂ O ₅ -P ₂ O ₅ -TeO ₂ . In this case, the ceramic powder may be V ₂ O ₅ -P ₂ O ₅ -TeO ₂ in terms of ensuring both mechanical strength and coercive force characteristics.

In addition, the magnetic powder and the ceramic powder may be mixed in a weight ratio of 5:5 to 9:1, more preferably in a weight ratio of 7:3 to 9:1.

In addition, the hot compression molding may be performed at a temperature of 100 to 200° C. higher than the melting point of the ceramic powder.

In addition, in step S3, a magnetic field may be further applied from the outside before hot compression molding or during hot compression molding.

In addition, the present invention provides a RE-Fe-B-TM-based ceramic bonded magnet manufactured through the manufacturing method according to the present invention described above, and a ceramic bonded magnet having a compressive strength of 400 MPa or more at 175°C.

The method of manufacturing a ceramic bonded magnet according to the present invention may be suitable for widespread use even in a high temperature environment as changes in mechanical strength such as compressive strength are minimized even if heat is generated at a high temperature due to an eddy current or exposure to a use temperature of 200°C or higher. have. In addition, as the mechanical strength is improved and physical property changes such as a reduction in coercivity that may occur are prevented, it can be widely applied to the entire industry, such as a rotating machine such as a motor.

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

The ceramic bonded 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 step S1 of preparing a magnetic powder containing crystal grains, the It can be prepared including a step S2 of preparing a mixed powder by kneading a ceramic powder having a melting point of 400° C. or less with the magnetic powder, and a step S3 of hot compression molding the mixed powder.

First, as step S1 according to the present invention, a step of preparing a magnetic powder having a composition of RE-Fe-B-TM (here, RE=rare earth element, TM=3d transition element) and containing crystal grains is performed.

The magnetic powder powder is an alloy having a RE-Fe-B-TM composition, and the element RE constituting the raw material alloy is a rare earth element, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, One or two or more selected from Ho, Er, Tm, Yb and Lu can be used. For example, the RE may be Nd in consideration of cost and magnetic properties. RE in the raw material alloy may be, for example, 28 to 35 at%.

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

In addition, the B may be contained in 0.5 ~ 1.5at% of the raw material alloy.

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

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

In addition, the alloy having the RE-Fe-B-TM-based composition can be produced through a known method of manufacturing a RE-Fe-B-based rare earth magnet, for example, an ingot or strip produced by a book mold method or a centrifugal casting method. It can be manufactured by a cast method. The prepared raw material alloy may be made of isotropic magnetic powder having crystal grains by using a known hydrogen decrepitaion desorption recombination (HDDR) method, or the raw material alloy may be made of isotropic magnetic powder having crystal grains through a known melt-spinning method. .

At this time, the magnetic powder may have an average particle diameter of 50 to 300 μm, more preferably 150 to 200 μm, and through this, there is an advantage of achieving an increased mechanical strength together with the ceramic powder to be described later. Further, more preferably, the magnetic powder has a particle diameter of ±30% or less, more preferably ±10% to ±30% with respect to a predetermined average particle diameter, and more preferably 60% or more of the total number of magnetic powders. In other words, it may be more advantageous to achieve an increased mechanical strength with ceramic powder to be described later through accounting for 30 to 40%.

At this time, the isotropic magnetic powder prepared through the HDDR method may contain fine grains of 200 to 300 nm, for example, and the isotropic magnetic powder prepared through the melt-spinning method may contain fine grains of 30 to 80 nm. I can.

Next, as step S2 according to the present invention, a step of preparing a mixed powder by kneading ceramic powder having a melting point of 400° C. or lower with the magnetic powder prepared in step S1 described above is performed.

The ceramic powder serves as a binder for bonding the magnetic powder. The ceramic powder having a melting point of 400° C. or less is used, and it may be advantageous to prevent a decrease in coercive force of the ceramic bonded magnet implemented through this. If a ceramic powder having a melting point exceeding 400°C is used, there may be a problem such as a decrease in coercivity due to the formation of an oxide layer at the interface of the ceramic powder due to hot compression molding. Preferably, the ceramic powder may have a melting point of 250 to 400° C., and if the melting point of the ceramic powder is insufficient, it may be difficult to use in a high-temperature environment.

The ceramic powder may be a known material having a melting point of 400° C. or less, but preferably V ₂ O ₅ -P ₂ O ₅ -TeO ₂ may be used, thereby preventing both excellent mechanical strength and coercive force fluctuations at high temperatures. It is advantageous to achieve.

In addition, the magnetic powder and the ceramic powder may be mixed in a weight ratio of 5:5 to 9:1, more preferably in a weight ratio of 7:3 to 9:1, through which more improved mechanical strength at high temperature and excellent magnetic It can be advantageous to achieve the enemy properties together.

Next, as step S3 according to the present invention, the step of hot compression molding the mixed powder may be performed.

The hot compression molding may be performed by appropriately employing a known hot compression molding method, and the present invention is not particularly limited thereto. At this time, preferably, the temperature during the hot compression molding may be performed at a temperature higher than the melting point of the ceramic powder by 100 to 200°C, and if performed at a temperature of less than 100°C, it may be difficult to sufficiently achieve mechanical strength, and exceed 200°C. There is a concern that the coercive force may decrease when performing with temperature.

On the other hand, the step S3 may further apply a magnetic field from the outside before hot compression molding or during hot compression molding, and through this, it may be advantageous to align the mixed powder in the magnetic field direction. Preferably, the strength of the applied magnetic field may be 1.0 to 2.0T, through which it may be advantageous to achieve the object of the present invention.

In addition, the ceramic bonded magnet manufactured through hot compression molding may be an isotropic magnet that maintains the isotropy of the magnetic powder, or may be an anisotropic magnet manufactured by further performing a hot deformation process applying a pressure of ^{0.5 ton/cm 2 or more.}

The ceramic bonded magnet manufactured by the above-described manufacturing method is a RE-B-TM-Fe-based ceramic bonded magnet, and may have a compressive strength of 400 MPa or more at 175°C, and a decrease in compressive strength compared to the compressive strength at room temperature, for example, 25°C This is 25% or less, preferably 20% or less, more preferably 10% or less, so that the mechanical strength at high temperature is very excellent, and there is little change in mechanical strength compared to room temperature, so that excellent quality can be maintained.

On the other hand, the ceramic bonded magnet has an excellent coercivity of 12.0 kOe or more and a specific resistance of 1.0 μΩ·cm×10 ³ or more, minimizing magnetic loss due to eddy current, and preventing physical property fluctuations due to heat generation.

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

<Example 1>

As a starting material, Nd, Fe, B, Nb, Ga are properly weighed, the components are mixed, melted, and alloyed using an alloy ingot, and the final Nd _12.5 Fe _80.6 B _6.4 Ga _0.3 Nb _0.2 (At this time, the content of each element is at%. ) An alloy raw material was prepared. Then, a magnetic powder having an average particle diameter of 160 μm having a grain size distribution of 200 to 500 nm was prepared using a conventional HDDR (Hydrogen decrepitaion desorption recombination) method. In addition, at this time, the magnetic powder was 36% of the total number of magnetic powders having a particle diameter of ±10% to ±30% of the average particle diameter.

Thereafter, ceramic powder having a melting point of V ₂ O ₅ -P ₂ O ₅ -TeO ₂ having a melting point of 280° C. was mixed in a weight ratio of 8:2 to prepare a mixed powder.

Thereafter, the mixed powder was hot compression molded in an argon atmosphere. Specifically, the horn powder was uniformly charged into a mold having a size of 12pi×15mm, and a magnetic field was applied from the outside at an intensity of 1.8T so that the mixed powder was aligned in the magnetic field direction. Thereafter, the temperature of the mold was heated to 420° C., which is about 140° C. higher than the melting point of the ceramic powder, ^{and pressurized at 1} ton/cm 2 to prepare an anisotropic ceramic bond magnet.

<Examples 2 to 3>

It was prepared in the same manner as in Example 1, but the anisotropic ceramic bonded magnet as shown in Table 1 was prepared by changing the mixing ratio of the ceramic powder as shown in Table 1 below.

<Comparative Examples 1 to 3>

Prepared in the same manner as in Example 1, but as shown in Table 1 below, the type of ceramic powder _{was changed to Bi 2} O-SiO ₂ -B ₂ O ₃ with a melting point of 550°C, and the temperature of the mold was 690°C during hot compression molding. Was changed to to prepare an anisotropic ceramic bonded magnet as shown in Table 1 below.

<Comparative Example 4>

Preparation was carried out in the same manner as in Example 1, but an epoxy bonded magnet as shown in Table 1 was prepared by mixing an epoxy resin to an amount of 3% by weight.

<Experimental Example 1>

For the ceramic bonded magnets prepared in Examples 1 to 3 and Comparative Examples 1 to 4, coercive force, specific resistance, and compressive strength at temperatures of 20°C and 175°C were measured, and are shown in Table 1 below.

At this time, the coercive force and specific resistance were measured using a B-H trace (applied magnetic field = 3 Tesla) and a 4 point probe (probe interval = 1 cm).

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Type of ceramic powder V ₂ O ₅ -P ₂ O ₅ -TeO ₂ Bi ₂ O-SiO ₂ -B ₂ O ₃ Epoxy resin
use Magnetic ratio and ceramic powder mixing weight ratio 8:2 7:3 9:1 8:2 7:3 9:1 8:2 Coercive force (Hcj, kOe) 12.6 12.5 12.5 10.2 7.7 12.0 12.5 Resistivity (μΩcm*10 ³ ) 0.84 1.30 0.41 0.81 1.27 0.44 0.35 Compressive strength (20℃, MPa) 523 589 490 512 569 485 65 Compressive strength (175℃, MPa) 412 461 402 403 447 392 21

As can be seen from Table 1, the ceramic bonded magnets of Examples 1 to 3 using ceramic powders having a melting point of 400° C. or less have similar levels compared to the ceramic bonded magnets of Comparative Examples 1 to 3 using ceramic powders having a melting point exceeding 400° C. It can be seen that there is little coercive force fluctuation while having the mechanical strength of.

<Example 4>

Prepared in the same manner as in Example 1, but the used magnetic powder was changed to an isotropic magnetic powder having an average particle diameter of 170 µm containing microcrystalline grains having a grain size range of 30 to 80 nm by a melt-spinning method, and an external magnetic field The mixed powder charged into the mold was heated to 420° C. without applying and ^{a pressure of 1 ton/cm 2} was applied to prepare an isotropic ceramic bonded magnet.

The prepared isotropic ceramic bonded magnet had a coercive force of 13.1 kOe and a specific resistance of 0.84 μΩcm×10 ³ .

Although an embodiment of the present invention has been described above, the spirit of the present invention is not limited to the embodiment presented in the present specification, and those skilled in the art who understand the spirit of the present invention can add components within the scope of the same idea It will be possible to easily propose other embodiments by changing, deleting, adding, etc., but it will be said that this is also within the scope of the present invention.

Claims (10)

S1 step of producing a magnetic powder containing a composition of RE-Fe-B-TM (here, RE = rare earth element, TM = 3d transition element) and crystal grains;
Step S2 of preparing a mixed powder by kneading _{V 2} O ₅ -P ₂ O ₅ -TeO ₂ as a ceramic powder having a melting point of 400° C. or less in the magnetic powder; And
S3 step of hot compression molding the mixed powder; ceramic bonded magnet manufacturing method comprising a. The method of claim 1,
The magnetic powder is a ceramic bonded magnet manufacturing method, characterized in that the isotropic magnetic powder having an average particle diameter of 50 ~ 300㎛. The method of claim 2,
The isotropic magnetic powder is a ceramic bonded magnet manufacturing method, characterized in that produced by HDDR or melt-spinning method. The method of claim 1,
In the above composition, RE is 28 ~ 35at%, B is 0.5 ~ 1.5at%, TM is 0 ~ 15at%, Fe is a ceramic bonded magnet manufacturing method, characterized in that included in the balance. delete The method of claim 1,
The method of manufacturing a ceramic bonded magnet, wherein the magnetic powder and the ceramic powder are mixed in a weight ratio of 5:5 to 9:1. The method of claim 1,
The method of manufacturing a ceramic bonded magnet, wherein the hot compression molding is performed at a temperature of 100 to 200° C. higher than the melting point of the ceramic powder. The method of claim 6,
The method of manufacturing a ceramic bonded magnet, wherein the magnetic powder and the ceramic powder are mixed in a weight ratio of 7:3 to 9:1. The method of claim 1,
The step S3 is a method of manufacturing a ceramic bonded magnet, wherein a magnetic field is further applied from the outside before or during hot compression molding. delete