WO2020009303A1 - Hybrid magnetic fiber and manufacturing method therefor - Google Patents

Abstract

A manufacturing method for a hybrid magnetic fiber is provided. The manufacturing method for a hybrid magnetic fiber may comprise the steps of: preparing a source solution comprising a first source material containing a rare earth element and a second source material containing a transition metal element; electrospinning the source solution to form a preliminary hybrid magnetic fiber containing a rare earth oxide and a transition metal oxide; and reducing the preliminary hybrid magnetic fiber to form a hybrid magnetic fiber, the hybrid magnetic fiber comprising: magnetic crystals containing a compound of the rare earth element and the transition metal element; and a magnetic boundary layer containing the transition metal element.

Description

Hybrid magnetic fiber and its manufacturing method

The present invention relates to a hybrid magnetic fiber and a method of manufacturing the same, and relates to a hybrid magnetic fiber including both hard magnetic and soft magnetic and a method of manufacturing the same.

The hard magnetic permanent magnets, which are widely applied to the electric and motor industries, are largely divided into rare earth-based magnets, and non-rare earth magnets such as ferrite and alnico. Rare earth magnets refer to compounds between rare earth metals and transition metals, and have a higher maximum magnetic energy ((BH) max) value than non-rare earth permanent magnets, which are essential to keep up with the recent weight reduction, miniaturization, and high performance of electronic products. It is an indispensable material. However, due to rising rare earth metal prices and unbalanced rare earth resource distribution, studies on rare earth reduction or non-rare earth magnet synthesis and alternative permanent magnet synthesis have been attempted.

For example, Korean Patent Publication No. 10-2017-0108468 (Application No .: 10-2016-0032417, Applicant: Yonsei University Industry-Academic Cooperation Foundation) includes a substrate, and a laminate formed on the substrate and formed of a Bi thin film layer and an Mn thin film layer. Disclosed is a coercive force-improved non-rare earth permanent magnet including a thin film laminate obtained by repeatedly laminating and heat-treating a unit at least two times and a method of manufacturing the same.

One technical problem to be solved by the present invention is to provide a hybrid magnetic fiber with improved coercivity and saturation magnetization and a method of manufacturing the same.

Another technical problem to be solved by the present invention is to provide a hybrid magnetic fiber having an improved maximum magnetic energy value and a method of manufacturing the same.

Another technical problem to be solved by the present invention is to provide a hybrid magnetic fiber with a reduced amount of rare earth and a method of manufacturing the same.

The technical problem to be solved by the present invention is not limited to the above.

In order to solve the above technical problem, the present invention provides a hybrid magnetic fiber manufacturing method.

According to an embodiment, the method of manufacturing a hybrid magnetic fiber may include preparing a source solution including a first source material including a rare earth element and a second source material including a transition metal element, and electrospinning the source solution. Forming a preliminary hybrid magnetic fiber comprising a rare earth oxide and a transition metal oxide, and reducing the preliminary hybrid magnetic fiber to form a magnetic crystal comprising a compound of the rare earth element and the transition metal element, And forming a hybrid magnetic fiber including a magnetic boundary layer including the transition metal element.

According to one embodiment, the magnetic crystal may include a hard-magnetic property, and the magnetic boundary layer may include a soft-magnetic property.

According to one embodiment, the magnetic boundary layer may include following the magnetization behavior of the magnetic crystal.

According to an embodiment, the mole fraction of the rare earth element in the source solution may include more than 9.290 at% and less than 10.562 at%.

According to an embodiment, the forming of the hybrid magnetic fibers may include mixing the preliminary hybrid magnetic fibers with a reducing agent, heat treating the preliminary hybrid magnetic fibers mixed with the reducing agent, and heat treating the preliminary hybrid magnetic fibers. It may include the step of washing with a washing solution.

According to an embodiment, the preliminary hybrid magnetic fiber mixed with the reducing agent may include heat treatment at a temperature of more than 500 ° C. and less than 800 ° C.

According to one embodiment, the reducing agent may include calcium (Ca).

According to one embodiment, the washing solution may include at least one of ammonium chloride (NH ₄ Cl), and methanol (CH ₃ OH).

According to an embodiment of the present disclosure, the source solution may further include a crystallization source including a metal and a viscous source including a polymer.

According to an embodiment, the rare earth element may include any one of La, Ce, Pr, Nd, Sm, or Gd.

According to one embodiment, the transition metal element may include any one of Fe, Co, or Ni.

In order to solve the above technical problem, the present invention provides a hybrid magnetic fiber.

According to an embodiment, the hybrid magnetic fibers may be disposed between a plurality of magnetic crystals including a rare earth element and a compound of a transition metal element, and the magnetic crystals adjacent to each other to surround the magnetic crystals, It may include a magnetic boundary layer (magnetic boundary layer) containing the transition metal element.

According to one embodiment, in the hybrid magnetic fiber, the volume fraction of the magnetic boundary layer may include more than 0 vol% less than 10 vol%.

According to an embodiment, the magnetic crystal may have a hard magnetic property, the magnetic boundary layer may have a soft magnetic property, and the magnetic boundary layer may include a magnetization behavior of the magnetic crystal.

In a method of manufacturing a hybrid magnetic fiber according to an embodiment of the present invention, preparing a source solution including a first source material including a rare earth element, and a second source material including a transition metal element, the source solution Electrospinning to form a preliminary hybrid magnetic fiber comprising a rare earth oxide and a transition metal oxide, and reducing the preliminary hybrid magnetic fiber to include a compound of the rare earth element and the transition metal element, and to exhibit hard magnetic properties. The method may include forming a hybrid magnetic fiber having a magnetic crystal having a magnetic crystal and a magnetic boundary layer including the transition metal element and having soft magnetic properties.

In addition, in the method of manufacturing a hybrid magnetic fiber according to the embodiment, by controlling the mole fraction of the rare earth element in the source solution, the volume fraction of the magnetic boundary layer in the hybrid magnetic fiber is controlled, as a result of the magnetic crystal And a magnetic exchange coupling effect between the magnetic boundary layers. Accordingly, saturation magnetization is increased while maintaining high coercivity, and further, the maximum magnetic energy ((BH) max) value is improved to provide a hybrid magnetic fiber exhibiting excellent magnetic properties. Can be.

1 is a flowchart illustrating a method of manufacturing a hybrid magnetic fiber according to an embodiment of the present invention.

2 is a flowchart illustrating a hybrid magnetic fiber forming step of the hybrid magnetic fiber manufacturing method according to an embodiment of the present invention in detail.

3 is a view showing a manufacturing process of a hybrid magnetic fiber according to an embodiment of the present invention.

4 is a view showing a hybrid magnetic fiber according to an embodiment of the present invention.

5 is a graph showing the characteristics of soft and hard magnetic materials.

FIG. 6 is a graph showing characteristics in the case where the self-exchange coupling effect is exhibited between soft magnetic and hard magnetic materials.

7 and 8 are photographs taken of the hybrid magnetic fiber according to Example 1 of the present invention.

9 to 11 are photographs comparing the characteristics of the heat treatment in the process of producing a hybrid magnetic fiber according to Example 1 of the present invention.

12 is a photograph comparing the influence of the washing solution in the process of washing the hybrid magnetic fiber according to Example 1 of the present invention.

13 is a photograph of a hybrid magnetic fiber according to Example 2 of the present invention.

14 is a graph showing an Sm-Co bicomponent system.

15 is a graph showing the effect of the mole fraction of rare earth elements contained in the source solution on the structure of the hybrid magnetic fiber according to Example 2 of the present invention.

16 and 17 are graphs showing the effect of the mole fraction of the rare earth elements contained in the source solution on the structure of the hybrid magnetic fiber according to Example 1 of the present invention.

18 is a graph showing the characteristics of a hybrid magnetic fiber according to a comparative example of the present invention in which no magnetic exchange coupling effect occurs.

19 is a graph showing the effect of the volume fraction of the magnetic boundary layer on the magnetic properties of the hybrid magnetic fiber according to Example 1 of the present invention.

20 is a graph showing the effect of the volume fraction of the magnetic crystals on the residual magnetization value of the hybrid magnetic fiber according to Example 1 of the present invention.

21 is a graph showing the effect of the volume fraction of the magnetic crystal on the maximum magnetic energy value of the hybrid magnetic fiber according to Example 1 of the present invention.

22 and 23 are graphs showing modification of the Recoil curve of the hybrid magnetic fibers according to Example 1 of the present invention, in which the volume fractions of the magnetic crystals and the magnetic crystal layers are different.

24 is a graph showing Recoil susceptibility values of hybrid magnetic fibers according to Example 1 of the present invention, in which the volume fractions of the magnetic boundary layers are different from each other.

25 to 27 is a graph comparing the characteristics of the heat treatment in the process of producing a hybrid magnetic fiber according to Example 1 of the present invention.

28 is a graph showing a change in characteristics of the rare earth oxide with respect to the heat treatment temperature.

29 to 31 are photographs and graphs comparing the diameters of the hybrid magnetic fibers according to Examples 1 and 3 of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical idea of the present invention is not limited to the exemplary embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed contents are thorough and complete, and that the spirit of the present invention can be sufficiently delivered to those skilled in the art.

In the present specification, when a component is mentioned to be on another component, it means that it may be formed directly on the other component or a third component may be interposed therebetween. In addition, in the drawings, the thicknesses of films and regions are exaggerated for effective explanation of technical contents.

In addition, in various embodiments of the present specification, terms such as first, second, and third are used to describe various components, but these components should not be limited by these terms. These terms are only used to distinguish one component from another. Thus, what is referred to as a first component in one embodiment may be referred to as a second component in another embodiment. Each embodiment described and illustrated herein also includes its complementary embodiment. In addition, the term 'and / or' is used herein to include at least one of the components listed before and after.

In the specification, the singular encompasses the plural unless the context clearly indicates otherwise. In addition, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, element, or combination thereof described in the specification, and one or more other features or numbers, steps, configurations It should not be understood to exclude the possibility of the presence or the addition of elements or combinations thereof. In addition, the term "connection" is used herein to mean both indirectly connecting a plurality of components, and directly connecting.

In addition, in the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

1 is a flow chart illustrating a method of manufacturing a hybrid magnetic fiber according to an embodiment of the present invention, Figure 2 is a flow chart illustrating the hybrid magnetic fiber forming step of the hybrid magnetic fiber manufacturing method according to an embodiment of the present invention in detail. 3 is a view showing a hybrid magnetic fiber manufacturing process according to an embodiment of the present invention, Figure 4 is a view showing a hybrid magnetic fiber according to an embodiment of the present invention.

1 to 4, a source solution including a first source material and a second source material may be prepared (S100). According to one embodiment, the first source material may include a rare-earth element. For example, the rare earth element may include any one of La, Ce, Pr, Nd, Sm, or Gd. According to one embodiment, the second source material may include a transition-metal element. For example, the transition metal element may include any one of Fe, Co, or Ni.

The source solution may further include a crystallization source, and a viscous source. According to one embodiment, the crystallization source may include a metal. For example, the metal may be a metal water-soluble salt such as copper (Cu) or zirconium (Zr). The crystallization source can improve the crystallinity of the hybrid magnetic fiber 100 to be described later. According to one embodiment, the viscous source may include a polymer. For example, the polymer may include at least one of polyvinylpyrrolidone (PVP), polyacrylonitrile (PAN), poly (vinyl acetate) (PVAC), polyvinylbutyral (PVB), poly (vinyl alcohol) (PVA), or polyethylene oxide (PEO). It may include. The viscous source may give viscosity to the source solution and control the diameter of the hybrid magnetic fiber 100 to be described later.

According to one embodiment, the mole fraction (at%) of the rare earth element in the source solution can be controlled. Specifically, the mole fraction of the rare earth element in the source solution may be controlled to be greater than 9.290 at% and less than 10.562 at%. In this case, an exchange-coupling effect may be generated between the magnetic crystal 110 and the magnetic boundary layer 120, which are included in the hybrid magnetic fiber 100 to be described later. In addition, the mole fraction of the rare earth element in the source solution may be controlled to more than 10.156 at% and less than 10.562 at%. In this case, the magnetic exchange coupling effect generated between the magnetic crystal 110 and the magnetic boundary layer 120 included in the hybrid magnetic fiber 100 to be described later may have a maximum value. A more detailed description will be given later.

The source solution is electrospun to form a preliminary hybrid magnetic fiber (S200). The preliminary hybrid magnetic fiber formed by electrospinning the source solution may include a rare earth oxide and a transition metal oxide.

According to an embodiment, the preliminary hybrid magnetic fiber forming step may include a first preliminary hybrid magnetic fiber forming step and a second preliminary hybrid magnetic fiber forming step. The first preliminary hybrid magnetic fiber forming step may be performed by electrospinning the source solution. The first preliminary hybrid magnetic fiber may be made of a solid component of the source solution. The first preliminary hybrid magnetic fiber may include a water-soluble metal salt, a polymer, and the like. The forming of the second preliminary hybrid magnetic fiber may be performed by calcining the first preliminary hybrid magnetic fiber. That is, the first preliminary hybrid magnetic fiber may be thermally treated to decompose an organic material including a polymer in the first preliminary hybrid magnetic fiber. The second preliminary hybrid magnetic fiber may include an oxide including all of a rare earth oxide, a transition metal oxide, and a rare earth-transition metal.

More specifically, the source solution may be injected into a syringe 10, and the source solution may be spun by using a syringe pump 20. In this case, the tip 30 of the syringe has an inner diameter of 0.05 to 2 mm, a collector in which the syringe tip 30 and the preliminary hybrid magnetic fibers are collected is spaced 10 to 20 cm apart, and the syringe pump 20 ) May spin the source solution at a rate of 0.3-0.8 mL / h. In addition, the voltage applied for electrospinning may be 16-23 kV. The first preliminary hybrid magnetic fiber may be formed through the above-described process.

The first preliminary hybrid magnetic fiber may be collected in an alumina crucible and heat-treated at atmospheric pressure of 500 to 900 ° C. in an atmospheric atmosphere. In this process, all organic materials including polymers can be thermally decomposed. At this time, the temperature increase rate condition may be 1 ~ 10 ℃ per minute. The second preliminary hybrid magnetic fiber may be formed through the above-described process.

The preliminary hybrid magnetic fibers may be reduced to form a hybrid magnetic fiber 100 including a magnetic crystal 110 and a magnetic boundary layer 120 (S300). According to one embodiment, the hybrid magnetic fiber 100 includes a plurality of the magnetic crystals 110, the magnetic boundary layer 120 is disposed between the magnetic crystals 110 adjacent to each other, the magnetic crystals It may have a structure surrounding the (110).

The magnetic crystal 110 may include a compound of the rare earth element and the electrometal element. For example, the magnetic crystal 110 may include Nd ₂ Fe ₁₄ B, Sm ₂ Co ₁₇ and the like. Accordingly, the magnetic crystal 110 may have a hard-magnetic characteristic. Alternatively, the magnetic boundary layer 120 may include the transition metal element. For example, the magnetic boundary layer 120 may include fcc-Fe, fcc-Co, and the like. Accordingly, the magnetic boundary layer 120 may have a soft magnetic property.

Unlike the above, according to another embodiment, the hybrid magnetic fiber 100 is a chain in which the first single crystal 110 of hard magnetic properties and the second single crystal 120 of soft magnetic properties are alternately and repeatedly arranged. It may have a structure.

That is, the hybrid magnetic fiber 100 according to the embodiment has a structure of any one of the magnetic crystal 110-magnetic boundary layer 120 structure, or the first single crystal 110-second single crystal 120 chain structure. Can be. The structure of the hybrid magnetic fiber 100, the conditions of the electrospinning process described above, the heat treatment conditions in the heat treatment reduction step described below, and the hard magnetic material, and soft magnetic material in the hybrid magnetic fiber 100 It can be determined according to the volume ratio and the like. Specifically, when controlled by the conditions of the electrospinning process, when the diameter of the hybrid magnetic fiber 100 is less than 500nm, the hybrid magnetic fiber 100 is the first single crystal 110-second single crystal 120 ) Can be formed into a chain structure. In addition, when the volume of the soft magnetic material is 10 vol% or more in the hybrid magnetic fiber 100, the hybrid magnetic fiber 100 may be formed in a first single crystal 110-second single crystal 120 chain structure. Can be.

The hybrid magnetic fibers 100 may have different industrial fields depending on the type of structure to be formed. For example, when the hybrid magnetic fiber 100 has a magnetic crystal 110-magnetic boundary layer 120 structure, the hybrid magnetic fiber 100 may be sintered to be used in a high output product in the form of a sintered magnet. In particular, it can be used in various advanced commercial equipment such as driving motors of hybrid vehicles (HEV) and electric vehicles (EVs), small motors for vehicles, VCMs for hard disks, speakers for mobile phones, small parts in industrial robots, and MRI.

On the contrary, when the hybrid magnetic fiber 100 has a first single crystal 110-second single crystal 120 chain structure, the hybrid magnetic fiber 100 is mixed with a binder material and molded to form a bond-based magnet ( Plastic magnet, rubber magnet). Although the magnetic properties are lower than that of the sintered magnet, it can be used for door packing of a refrigerator, paperweight of a bulletin board, various stationery, etc. due to its high workability, seismic resistance, and impact resistance.

According to one embodiment, the forming of the hybrid magnetic fiber 100 (S300), the step of mixing the preliminary hybrid magnetic fiber with a reducing agent (S310), the step of heat-treating the preliminary hybrid magnetic fiber mixed with the reducing agent ( S320), and washing the heat-treated preliminary hybrid magnetic fiber with a washing solution (S330). That is, after the preliminary hybrid magnetic fiber 100 is mixed with a reducing agent and heat-treated, the hybrid magnetic fiber 100 may be formed.

The reducing agent may include calcium (Ca). For example, the reducing agent may include CaH ₂ . In this case, the hybrid magnetic fiber 100 may be easily formed. Specifically, in the case of rare earth elements, it has a very small oxidation energy, it is possible to maintain the most stable phase in the form of oxides. Accordingly, in order to reduce the rare earth oxide to metal, a high temperature of 1500 ° C. or higher and a hydrogen atmosphere are required, and process difficulties are generated. However, since calcium (Ca) has a smaller oxidation energy than rare earth elements, when used as a reducing agent, a relatively low heat treatment temperature (for example, 500 to 800 ° C.) and a rare earth oxide in a non-hydrogen atmosphere are used. Can be easily reduced.

The heat treatment temperature of the preliminary hybrid magnetic fiber mixed with the reducing agent may be controlled. Specifically, the preliminary hybrid magnetic fiber mixed with the reducing agent may be heat-treated at a temperature of more than 500 ℃ less than 800 ℃. In this case, the hybrid magnetic fiber 100 may be easily formed. On the contrary, when the preliminary hybrid magnetic fiber mixed with the reducing agent is heat-treated at a temperature of 500 ° C. or less, a problem may occur in which the reduction is not performed because the temperature is too low. In addition, when the preliminary hybrid magnetic fiber mixed with the reducing agent is heat-treated at a temperature of 800 ° C. or more, the hybrid magnetic fiber 100 may not be in the form of a fiber and may be deformed into a particle form.

The washing solution may include at least one of ammonium chloride (NH ₄ Cl), and methanol (CH ₃ OH). In this case, the hybrid magnetic fiber 100 may be easily formed. Specifically, when the preliminary hybrid magnetic fiber is reduced by using a reducing agent including calcium (Ca), calcium oxide (CaO) may be formed on the metal surface of which the rare earth oxide is reduced. Accordingly, a process for removing calcium oxide (CaO) is required, and a conventional calcium oxide (CaO) removing process uses a washing solution in which acetic acid or hydrochloric acid is mixed with ultrapure water. In this case, a problem may occur when the acid solution causes a fatal effect such as corrosion or oxidation even on the magnetic phase. However, in the case of the washing solution containing at least one of ammonium chloride (NH ₄ Cl) and methanol (CH ₃ OH), calcium oxide (CaO) can be easily removed without affecting the magnetic phase. .

According to one embodiment, in the hybrid magnetic fiber 100, the volume fraction (vol%) of the magnetic boundary layer 120 may be controlled. Specifically, in the hybrid magnetic fiber 100, the volume fraction of the magnetic boundary layer 120 may be controlled to more than 0 vol% less than 10 vol%. In this case, the magnetic boundary layer 120 may follow the magnetization behavior of the magnetic crystal 110. That is, an exchange-coupling effect may be generated between the magnetic crystal 110 and the magnetic boundary layer 120. In addition, in the hybrid magnetic fiber 100, the volume fraction of the magnetic boundary layer 120 may be controlled to more than 0 vol% less than 3 vol%. In this case, the magnetic exchange coupling effect generated between the magnetic crystal 110 and the magnetic boundary layer 120 may have a maximum value.

5 is a graph showing the characteristics of the soft magnetic and hard magnetic material, Figure 6 is a graph showing the characteristics when the magnetic exchange coupling effect between the soft magnetic and hard magnetic material.

5 and 6, in the case of the soft magnetic material, as shown in FIG. 5A, saturation magnetization (M _s ) is relatively high, and coercivity (H _C ) is relatively high. It may have a low appearance. On the other hand, in the case of the hard magnetic material, as shown in FIG. 5 (b), the coercive force (H _C ) may be relatively high, and the saturation magnetization (M _s ) may be relatively low. However, when a magnetic exchange coupling effect occurs between the soft magnetic material and the hard magnetic material, as shown in FIG. 6, both coercive force (H _c ) and saturation magnetization (M _S ) may be high. As a result, a material exhibiting a self-exchange effect between the hard magnetic material and the soft magnetic material has excellent magnetic properties and can be easily used as a permanent magnet.

As described above, the hybrid magnetic fiber 100 according to the embodiment, the magnetic crystal 110 of the hard magnetic properties included in the hybrid magnetic fiber 100, and the magnetic boundary layer 120 of the soft magnetic properties A self-exchange effect may occur between them. To this end, the volume fraction of the magnetic boundary layer 120 in the hybrid magnetic fiber 100 can be controlled. In addition, the volume fraction of the magnetic boundary layer 120 in the hybrid magnetic fiber 100 may be controlled by the mole fraction of the rare earth element in the source solution. The mole fraction of the rare earth element in the source solution according to the volume fraction of the magnetic boundary layer 120 in the hybrid magnetic fiber 100 may be calculated through Equation 1 below.

<Equation 1>

(RE (at.%)): Mole fraction of rare earth elements in the source solution, ρ _hard : density of magnetic crystals, x _hard : Volume fraction of magnetic crystals in the hybrid magnetic fibers (0.0 to 1.0), m _RE : Number of atoms of rare earth elements in the magnetic crystal (eg m _RE = 2 in Sm ₂ Co ₁₇ ), MW _hard : Molecular weight of magnetic crystals, ρ _soft : Density of the magnetic boundary layer, m _TM: atomic number of crystals in the magnetic transition metal element (for example, in the _{Sm 2 Co 17 m TM = 17} ), MW soft: Molecular weight of the magnetic boundary layer)

That is, by controlling the mole fraction of the rare earth element in the source solution, the volume fraction of the magnetic boundary layer 120 in the hybrid magnetic fiber 100 is controlled, resulting in the magnetic crystal 110 and the magnetic boundary layer. A self-exchange coupling effect between 120 may occur. Specifically, when the mole fraction of the rare earth element in the source solution is controlled to be greater than 9.290 at% and less than 10.562 at%, the volume fraction of the magnetic boundary layer 120 in the hybrid magnetic fiber 100 is greater than 0 vol% 10. It can be controlled to less than vol%. In this case, a magnetic exchange coupling effect may occur between the magnetic crystal 110 and the magnetic boundary layer 120. As a result, the hybrid magnetic fiber 100 according to the embodiment exhibits a high magnetic property, it can be easily used as a permanent magnet. In other words, the hybrid magnetic fiber 100 according to the embodiment may exhibit high magnetic properties through the mixing of the hard magnetic material and the soft magnetic material, so that the use of the rare earth material for manufacturing the permanent magnet may be reduced. Can be.

Unlike the method of manufacturing the hybrid magnetic fiber according to the above-described embodiment, conventionally, in order to mix the hard magnetic material and the soft magnetic material, a simple mixing method, a coating method, a deposition method, a bulk process, a plasma process, and the like Was used.

In the case of the simple mixing method, as a method of physically bonding the hard magnetic nanopowder and the soft magnetic nanopowder, there is a disadvantage that a process such as sintering must be additionally performed in order to generate a self-exchange coupling effect.

In the coating method, a soft-magnetic material is coated on the hard magnetic material to form a core-shell structured material. Typically, a sol-gel coating method is used. In the sol-gel coating method, nano-powders such as chemical reaction of hard magnetic material in air and hydrogen heat treatment for sol formation and reduction, oxidation of demagnetizing material in heat treatment to remove organic matter, etc. Since it is very susceptible to surface oxidation, ferrite in the form of oxide is mainly used. Accordingly, there is a problem that it is difficult to expect higher magnetic properties than commercial hard magnetic materials.

In the deposition method, a composite powder is prepared by coating a soft magnetic material on the surface of a hard magnetic material by electroless or electrolytic deposition.A process of dipping a light magnetic material in an acid solution containing hydrochloric acid (HCl) and ammonia solution Oxidation and surface defects of the hard magnetic material may be generated from the process of using the basic plating solution. Accordingly, the use of the ferrite in a stable oxide form is limited, and when the soft magnetic coating layer prepared as a result of the deposition is an oxide, there is a problem that an additional reduction heat treatment process must be accompanied.

For the bulk process, there are techniques for producing hard and soft magnetic alloys from high purity metal ingots or for depositing hybrid structures of hard and soft magnetic materials through subsequent heat treatment of amorphous hard magnetic materials, Magnetic properties can be expected, but due to the low coercivity, there is a problem that the range of use for the bonded magnet is limited.

In the plasma process, it is possible to produce nano-sized hard magnetic and soft magnetic composite powders in an inert atmosphere, but it requires 5,000 to 10,000 K high-grade heat source for the vaporization and dissolution of the powder, difficult to control the size and amount In the powder collection process, the reactivity of the nano powder with the gas may occur.

However, the method of manufacturing a hybrid magnetic fiber according to an embodiment of the present invention, preparing a source solution comprising a first source material containing a rare earth element, and a second source material containing a transition metal element, the Electrospinning a source solution to form the preliminary hybrid magnetic fiber comprising a rare earth oxide and a transition metal oxide, and reducing the preliminary hybrid magnetic fiber to include a compound of the rare earth element and the transition metal element, Forming the hybrid magnetic fiber 100 including the magnetic crystal 110 having a hard magnetic property and the magnetic boundary layer 120 including the transition metal element and having a soft magnetic property. It may include the step.

In addition, in the method of manufacturing a hybrid magnetic fiber according to the embodiment, the volume fraction of the magnetic boundary layer 120 in the hybrid magnetic fiber 100 is controlled by controlling the mole fraction of the rare earth element in the source solution. As a result, a magnetic exchange coupling effect may be generated between the magnetic crystal 110 and the magnetic boundary layer 120. Accordingly, saturation magnetization is increased while maintaining high coercivity, and further, the maximum magnetic energy ((BH) max) value is improved to provide a hybrid magnetic fiber exhibiting excellent magnetic properties. Can be.

In the above, the hybrid magnetic fiber and the manufacturing method thereof according to the embodiment of the present invention have been described. Hereinafter, specific experimental examples and characteristics evaluation results of the hybrid magnetic fiber and its manufacturing method according to the embodiment of the present invention will be described.

Hybrid magnetic fiber production according to Example 1

Samarium (III) nitrate hexahydrate (Smrium (III) nitrate hexahydrate; Sm (NO ₃ ) ₃ 6H ₂ O) and cobalt (II) nitrate hexahydrate (Cobalt (II) nitrate hexahydrate; Co (NO ₃₎ ) ₂ 6H ₂ O) and a solution of 0.4g of PVP having a molecular weight of 1,300,000 in 6 mL of ethanol was mixed to prepare a source solution.

The prepared source solution is placed in a syringe for electrospinning and continuously pushed at a rate of 0.3 to 0.8 mL / h using a syringe pump. At this time, the tip of the syringe and the collector in which the spun fibers are collected are spaced apart at intervals of 15 cm, and a high voltage (16-23 kV) is applied so that the source solution is spun by the potential difference. The material deposited on the collector is collected in an alumina (alumina, Al ₂ O ₃ ) crucible and heat treated at an air temperature of about 700 ° C. for 3 hours to decompose all organic materials including polymers. In the process the rare earth-containing oxide of SmCoO ₃ -Co ₃ O ₄ - a spare magnetic hybrid fibers comprising a transition metal oxide can be obtained.

The preliminary hybrid magnetic fibers were mixed with CaH ₂ in a volume ratio of 1: 1 and reduced by heat treatment for 3 hours at a temperature of about 700 ° C. in an inert atmosphere, followed by washing with ammonium chloride and methanol to give Sm of hard magnetic properties. _A hybrid magnetic fiber according to the first embodiment including a ₂ Co ₁₇ magnetic crystal and a fcc-Co magnetic boundary layer having soft magnetic properties was prepared.

In addition, in order to control the volume fraction of the Sm ₂ Co ₁₇ magnetic crystal in the hybrid magnetic fiber according to the first embodiment, the mole fraction of the samarium element in the source solution was controlled, which is calculated through Equation 2 below. The calculated results are summarized in <Table 1>.

<Equation 2>

(Sm (at%): a rare earth element molar fraction in the source solution, ρ _Sm2Co17: Sm ₂ Co ₁₇ the density of the magnetic crystals, x _Sm2Co17: volume of Sm ₂ Co ₁₇ magnetic crystal in the hybrid magnetic fiber fraction (0.0 ~ 1.0), m _Sm : number of atoms of rare earth elements in magnetic crystals, MW _Sm2Co17 : molecular weight of magnetic crystals ρ _Co : density of magnetic boundary layers, m _Co : number of atoms of transition metal elements in magnetic crystals, MW _Co : molecular weight of magnetic boundary layers)

Volume fraction of magnetic crystals in hybrid magnetic fibers (Sm 2 Co 17 vol%)	Mole fraction of rare earth elements in the source solution (Sm at%)
100	10.562
99	10.409
97	10.156
95	9.906
90	9.290
80	8.101
50	4.803
30	2.786
10	0.885
0	0

Hybrid magnetic fiber production according to Example 2

Neodymium (III) nitrate hexahydrate (Nd (NO ₃ ) ₃ 6H ₂ O) and iron (III) nitrate hexahydrate (Iron (III) nitrate nonahydrate; Fe (NO ₃ ) in 4.5 mL ultrapure water ) ₃ 9H ₂ O) and a solution of 0.6 g of PVP having a molecular weight of 1,300,000 in 3 mL of ethanol was mixed to prepare a source solution. In addition, boric acid (H ₃ BO ₃ ) was further mixed as much as half the number of moles of neodymium (III) nitrate hexahydrate.

The prepared source solution is placed in a syringe for electrospinning and continuously pushed at a rate of 0.3 to 0.8 mL / h using a syringe pump. At this time, the tip of the syringe and the collector in which the spun fibers are collected are spaced at an interval of 18 cm, and a high voltage (16-23 kV) is applied so that the source solution is spun by the potential difference. The material deposited on the collector is collected in an alumina (alumina, Al ₂ O ₃ ) crucible and heat treated at an air temperature of about 700 ° C. for 3 hours to decompose all organic materials including polymers. In this process, a preliminary hybrid magnetic fiber containing a rare earth oxide-transition metal oxide of NdFeO ₃ -NdBO ₃ -Fe ₂ O ₃ is obtained.

The preliminary hybrid magnetic fibers were mixed with CaH ₂ in a volume ratio of 1: 1 and reduced by heat treatment for 3 hours at a temperature of about 700 ° C. in an inert atmosphere, followed by washing with ammonium chloride and methanol to give Nd of hard magnetic properties. _A hybrid magnetic fiber according to a second embodiment including a ₂ Fe ₁₄ B magnetic crystal and a fcc-Fe magnetic boundary layer having soft magnetic properties was prepared.

In addition, in order to control the volume fraction of Nd ₂ Fe ₁₄ B magnetic crystals in the hybrid magnetic fiber according to the second embodiment, the mole fraction of the neodymium element in the source solution was controlled, which was calculated through Equation 3 below. The calculated results are summarized in <Table 2>.

<Equation 3>

(Nd (at%): mole fraction of rare earth elements in the source solution, ρ _Nd2Fe14B : density of Nd ₂ Fe ₁₄ B magnetic crystals, x _Nd2Fe14B : volume fraction of Nd ₂ Fe ₁₄ B magnetic crystals in a hybrid magnetic fiber (0.0 to 1.0) , m _Nd : number of atoms of the rare earth element in the magnetic crystal, MW _Nd2Fe14B : molecular weight of the magnetic crystal ρ _Fe : density of the magnetic boundary layer, m _Fe : number of atoms of the transition metal element in the magnetic crystal, MW _Fe : molecular weight of the magnetic boundary layer)

Volume fraction of magnetic crystals in hybrid magnetic fibers (Nd 2 Fe 14 B vol%)	Mole fraction of rare earth elements in the source solution (Nd at%)
100	12.505
99	12.348
97	12.037
95	11.729
90	10.973
80	9.515
50	5.541
30	3.180
10	1.016
0	0

In addition, the configuration of the hybrid magnetic fibers according to the first embodiment and the second embodiment is summarized through <Table 3> below.

division	Magnetic crystal	Magnetic boundary layer
Example 1	Sm 2 Co 17	Co
Example 2	Nd 2 Fe 14 B	Fe

Hybrid magnetic fiber production according to Example 3

A hybrid magnetic fiber according to Example 1 was prepared, but manufactured to have a diameter of 250 nm or less, thereby preparing a hybrid magnetic fiber according to Example 3 having a chain structure of hard magnetic property single crystal-soft magnetic property single crystal.

The structure of the hybrid magnetic fibers according to Examples 1 to 3 is summarized through Table 4 below.

division	rescue
Example 1	Magnetic Crystal-Magnetic Boundary Layer Structure
Example 2	Magnetic Crystal-Magnetic Boundary Layer Structure
Example 3	Monocrystalline-Single Crystal Chain Structure

7 and 8 are photographs taken of the hybrid magnetic fiber according to Example 1 of the present invention.

Referring to FIGS. 7 and 8, the hybrid magnetic fiber according to Example 1, wherein the mole fraction of the rare earth element in the source solution is controlled to 10.56 at%, 0 at%, 9.91 at%, and 4.80 at%, is SEM Scanning electron microscope images were taken and shown in FIGS. 7A, 7B, 8A, and 8B, respectively. As shown in FIG. 7 and FIG. 8, it was confirmed that the hybrid magnetic fiber according to Example 1 was formed in a fiber shape having a diameter of about 500 nm.

9 to 11 are photographs comparing the characteristics of the heat treatment in the process of producing a hybrid magnetic fiber according to Example 1 of the present invention.

9 to 11, the temperature according to the heat treatment in the reduction step of the preliminary hybrid magnetic fiber is controlled to 400 ℃, 500 ℃, 600 ℃, 700 ℃, 750 ℃, and 800 ℃ the hybrid according to Example 1 formed SEM images of the magnetic fibers were carried out in FIGS. 9A, 9B, 10A, 10B, 11A, and 11B, respectively. Indicated.

As can be seen in Figures 9 (a) and (b), when the temperature is 400 ℃ and 500 ℃ heat treatment in the reduction step, it was confirmed that the rare earth oxide is not easily reduced. In addition, as can be seen in Figure 11 (a) and (b), when the temperature to be heat-treated in the reduction step is 750 ℃ and 800 ℃, it could be confirmed that the shape of the fiber does not maintain the shape of the particles. On the other hand, as can be seen in Figure 10 (a) and (b), when the temperature is heat treated in the reduction step of 600 ℃ and 700 ℃, it is easy to reduce the rare earth oxide, it is confirmed that the hybrid magnetic fiber is easily formed Could.

12 is a photograph comparing the influence of the washing solution in the process of washing the hybrid magnetic fiber according to Example 1 of the present invention.

12 (a) and 12 (b), in the process of washing the hybrid magnetic fiber according to Example 1, the case where the ammonium chloride and methanol are washed with the washing solution according to the embodiment of FIG. As shown in (a), the case of washing with a conventional washing solution mixed with ultrapure water and weak acid is shown in (b) of FIG. As can be seen in (a) and (b) of Figure 12, when washed with the existing washing solution, by-products remain on the surface of the fiber to reduce the magnetic properties, while when washed with the washing solution according to the embodiment, the magnetic By-products except fibers were selectively removed, and it was confirmed that magnetic properties reaching theoretical values were obtained.

13 is a photograph of a hybrid magnetic fiber according to Example 2 of the present invention.

Referring to (a) to (c) of Figure 13, SEM of the hybrid magnetic fiber according to Example 2 formed by controlling the mole fraction of the rare earth element in the source solution is controlled to 12.5 at%, 3.18 at%, and 0 at% The photographs are shown in FIGS. 13A to 13C, respectively. As can be seen from (a) to (c) of FIG. 13, even when Nd was used as the rare earth element and Fe was used as the transition metal element, it was confirmed that hybrid magnetic fibers were easily formed.

14 is a graph showing an Sm-Co bicomponent system.

Referring to FIG. 14, the state of the Sm-Co compound according to the mole fraction (at%) and temperature (° C.) of Sm in the Sm-Co compound is shown. As can be seen in Figure 14, when the mole fraction of Sm in the Sm-Co compound is less than 10.6 at%, it was confirmed that the hard magnetic properties and soft magnetic properties coexist.

15 is a graph showing the effect of the mole fraction of rare earth elements contained in the source solution on the structure of the hybrid magnetic fiber according to Example 2 of the present invention.

Referring to (a) to (c) of FIG. 15, the hybrid magnetic material according to Example 2, wherein the mole fraction of the rare earth element Nd in the source solution is controlled to 12.5 at%, 3.18 at%, and 0 at%, is formed. X-ray diffraction analysis was shown by measuring the relative intensity (au) according to 2θ (degree) for each fiber. As can be seen in FIG. 15 (a), when the mole fraction of the rare earth element in the source solution is 12.5 at%, only the hard magnetic properties of Nd ₂ Fe ₁₄ B were found. In addition, as can be seen in Figure 15 (c), when the mole fraction of the rare earth element in the source solution is 0 at%, it was confirmed that only the soft magnetic properties of fcc-Fe. However, as can be seen in Figure 15 (b), when the mole fraction of the rare earth element in the source solution is 3.15 at%, it is confirmed that both the hard magnetic properties of Nd ₂ Fe ₁₄ B and the soft magnetic properties of fcc-Fe appear Could.

16 and 17 are graphs showing the effect of the mole fraction of the rare earth elements contained in the source solution on the structure of the hybrid magnetic fiber according to Example 1 of the present invention.

16 and 17, the hybrid magnetic fiber according to Example 2, wherein the mole fraction of rare earth element (Sm) in the source solution is controlled to be 10.56 at%, 0 at%, 9.91 at%, and 4.80 at% X-ray diffraction analysis by measuring the relative intensity (au) according to 2θ (degree) for each, and these are respectively (a) of Figure 16, (b) of Figure 16, (a) of Figure 17, and Figure 17 It is shown in (b).

As can be seen from (a) of Figure 16, when the mole fraction of the rare earth element in the source solution is 10.56 at%, it was confirmed that only the magnetic properties of Sm ₂ Co ₁₇ appears. In addition, as can be seen in Figure 16 (b), when the mole fraction of the rare earth element in the source solution is 0 at%, it was confirmed that only the soft magnetic properties of fcc-Co. However, as shown in (a) and (b) of FIG. 17, when the mole fraction of rare earth elements in the source solution is 9.91 at%, and 4.80 at%, the hard magnetic properties of Sm ₂ Co ₁₇ and All of the soft magnetic properties were confirmed.

18 is a graph showing the characteristics of a hybrid magnetic fiber according to a comparative example of the present invention in which no magnetic exchange coupling effect occurs.

Referring to FIG. 18, an Applied field (kOe) of a hybrid magnetic fiber according to a comparative example of the present invention, in which Sm ₂ Co ₁₇ light magnetic material and fcc-Co soft magnetic material are simply mixed in a volume ratio of 50 vol%: 50 vol%. Magnetization (emu / g) was measured according to) and the magnetic hysteresis curve was shown. As can be seen in FIG. 18, the hybrid magnetic fiber according to Example 1, in which the volume fraction of the Sm ₂ Co ₁₇ magnetic crystal and the fcc-Co magnetic boundary layer was controlled to 50 vol%: 50 vol%, was considered to exhibit a kink phenomenon. , It was confirmed that the effect of the auto-exchange coupling did not occur.

19 is a graph showing the effect of the volume fraction of the magnetic boundary layer on the magnetic properties of the hybrid magnetic fiber according to Example 1 of the present invention.

Referring to FIG. 19, magnetization (emu / g) according to the applied field (Oe) of the hybrid magnetic fiber according to Example 1, in which the volume fraction of the fcc-Co magnetic boundary layer was controlled, was measured to show a magnetic history curve. As can be seen in Figure 19, in the case of the hybrid magnetic fiber according to the first embodiment of the present invention, unlike the hybrid magnetic fiber according to the comparative example shown in Figure 18, the kink phenomenon does not appear in the magnetic hysteresis curve, the magnetic exchange coupling effect Was confirmed to occur.

In addition, the magnetic properties of the hybrid magnetic fiber according to the first embodiment having a different volume fraction of the fcc-Co magnetic boundary layer is summarized through Table 5 below.

Volume fraction of Fcc-Co magnetic boundary layer (vol%)	Saturation Magnetization M s (emu / g)	Residual Magnetization M r (emu / g)	Susceptibility M r / M s (%)	Coercivity H ci (Oe)	Max Magnetic Energy (BH) max (MGOe)
0	84.390	58.509	69.332	7044.6	7.001
0.3	88.176	60.696	68.835	6953.3	N / A
One	87.265	59.559	68.251	6953.7	7.577
1.5	87.550	59.756	68.253	6741.5	N / A
3	87.887	58.706	66.797	6513.4	7.429
5	97.310	63.135	64.880	6193.0	7.208
7	98.377	62.070	63.094	5721.2	6.398
10	98.760	60.329	61.087	5128.0	6.010
20	99.444	54.478	54.783	3672.1	N / A
30	109.350	52.182	47.720	2526.2	N / A
50	124.670	47.231	37.885	1208.9	N / A
70	138.460	40.602	29.324	604.1	N / A
100	164.600	25.245	15.337	162.5	0.401

As can be seen from Table 5, the hybrid magnetic fiber according to Example 1 exhibits the highest maximum magnetic energy ((BH) _max ) value when the volume fraction of the fcc-Co magnetic boundary layer is 1 vol%. I could confirm it. Accordingly, when the volume fraction of the fcc-Co magnetic boundary layer is 1 vol%, it was found that the effect of the magnetic exchange coupling between the Sm ₂ Co ₁₇ magnetic crystal and the fcc-Co magnetic boundary layer is maximized.

Theoretically, in order to generate a magnetic exchange coupling force between the hard magnetic material and the soft magnetic material, the size of the soft magnetic material should be smaller than twice the domain-wall width of the magnetic domain boundary. The theoretical size of the fcc-Co magnetic boundary layer, which is necessary to exhibit the effect of the magnetic exchange coupling between the Sm ₂ Co ₁₇ magnetic crystal and the fcc-Co magnetic boundary layer, is about 20.0 nm, which is less than about 5 at% when calculated by volume fraction. It can be seen that it is substantially in agreement with the experimental data of the invention.

20 is a graph showing the effect of the volume fraction of the magnetic crystals on the residual magnetization value of the hybrid magnetic fiber according to Example 1 of the present invention.

Referring to FIG. 20, the residual magnetization value (Remanence, M _r (emu / g)) of the hybrid magnetic fiber according to Example 1, in which the volume fraction of the Sm ₂ Co ₁₇ magnetic crystal is controlled, is shown. As shown in FIG. 20, when the volume fraction of the Sm ₂ Co ₁₇ magnetic crystal was 90 vol% or more, it was confirmed that the residual magnetization value was higher than that of the Sm ₂ Co ₁₇ single phase.

21 is a graph showing the effect of the volume fraction of the magnetic crystal on the maximum magnetic energy value of the hybrid magnetic fiber according to Example 1 of the present invention.

Referring to FIG. 21, the maximum magnetic energy value (Energy product, (BH) _max (MGOe)) of the hybrid magnetic fiber according to Example 1, in which the volume fraction of the Sm ₂ Co ₁₇ magnetic crystal is controlled, is shown. As can be seen in FIG. 21, when the volume fraction of the Sm ₂ Co ₁₇ magnetic crystal was 99 vol%, the maximum magnetic energy value was found to be the highest as 7.577 MGOe.

As can be seen from Figure 19 to 21, the hybrid magnetic fiber according to Example 1, when the volume fraction of the fcc-Co magnetic boundary layer is greater than 0 vol% less than 3 vol%, Sm ₂ Co ₁₇ magnetic crystals and fcc- It can be seen that the magnetic exchange coupling effect easily occurs between the Co magnetic boundary layers.

22 and 23 are graphs showing modification of the Recoil curve of the hybrid magnetic fibers according to Example 1 of the present invention, in which the volume fractions of the magnetic crystals and the magnetic crystal layers are different.

22 and 23, when the volume fraction of the Sm ₂ Co ₁₇ magnetic crystal and the fcc-Co magnetic crystal layer is 97 vol%: 3 vol%, 95 vol%: 5 vol%, and 70 vol% In the case of 30 vol%, magnetization (emu / g) according to the Applied Field (Oe) was measured, and the Recoil curve modifications are shown in FIGS. 22A, 22B, and 23. .

As can be seen from (a) and (b) of FIG. 22, when the volume fraction of the Sm ₂ Co ₁₇ magnetic crystal and the fcc-Co magnetic crystal layer is 97 vol%: 3 vol%, 95 vol%: 5 vol% In the case of the hybrid magnetic fiber according to Example 1, it was confirmed that a closed loop (closed loop) appears. On the other hand, as can be seen in Figure 23, when the volume fraction of the Sm ₂ Co ₁₇ magnetic crystals and fcc-Co magnetic crystal layer is 70 vol%: 30 vol% hybrid magnetic fiber according to the first embodiment, the open loop ( opened loop) appears. In the case of the hybrid magnetic fiber showing the closed loop, the magnetic exchange coupling effect between the Sm ₂ Co ₁₇ magnetic crystal and the fcc-Co magnetic crystal layer is shown, but in the case of the hybrid magnetic fiber showing the open loop, the Sm ₂ Co ₁₇ magnetic crystal and It means that the magnetic exchange coupling effect does not appear between the fcc-Co magnetic crystal layer.

24 is a graph showing Recoil susceptibility values of hybrid magnetic fibers according to Example 1 of the present invention, in which the volume fractions of the magnetic boundary layers are different from each other.

Referring to FIG. 24, when the volume fraction of the fcc-Co magnetic boundary layer is greater than 1 vol% (Co-excess-1), greater than 3 vol% (Co-excess-3), and greater than 5 vol% ( Co-excess-5), and for each of the hybrid magnetic fibers according to example 1 above 30 vol% (Co-excess-30), dM / dH (emu / (g. Oe)) was measured to indicate the value of Recoil susceptibility.

As can be seen in Figure 24, when the volume fraction of the fcc-Co magnetic boundary layer is greater than 1 vol% (Co-excess-1), greater than 3 vol% (Co-excess-3), and greater than 5 vol% Hybrid magnetic fiber according to Example 1 of the case (Co-excess-5) was confirmed that one peak (peak) appears. However, the hybrid magnetic fiber according to Example 1 above when the volume fraction of the fcc-Co magnetic boundary layer is greater than 30 vol% (Co-excess-30) has two peaks at about −7 kOe and −2.5 kOe. It was confirmed that (peak) appeared. In the graph showing the Recoil susceptibility value, one peak means that a magnetic exchange coupling effect occurs between the Sm ₂ Co ₁₇ magnetic crystal and the fcc-Co magnetic crystal layer, and the two peaks indicate the Sm ₂ Co ₁₇ magnetic crystal and fcc- It means that the magnetic exchange coupling effect does not appear between the Co magnetic crystal layers.

25 to 27 is a graph comparing the characteristics of the heat treatment in the process of producing a hybrid magnetic fiber according to Example 1 of the present invention.

25 to 27, the hybrid according to Example 1, wherein the temperature to be heat-treated in the reduction step of the preliminary hybrid magnetic fiber is controlled to be 400 ° C., 500 ° C., 600 ° C., 700 ° C., 750 ° C., and 800 ° C. For each of the magnetic fibers, Relative intensity (au) according to 2theta (deg.) Was measured to show an X-ray diffraction pattern. Hybrid magnetic fibers heat treated at temperatures of 400 ° C., 500 ° C., 600 ° C., and 700 ° C. are shown in FIG. 25, and hybrid magnetic fibers heat treated at temperatures of 700 ° C., 750 ° C., and 800 ° C. are shown in FIG. 26. FIG. 27 is an enlarged graph of part A of FIG. 26.

As can be seen in Figures 25 to 27, when the temperature to be heat-treated in the reduction step is 400 ℃ and 500 ℃, the rare earth oxide is not easily reduced, the Sm ₂ Co ₁₇ magnetic crystals and fcc-Co magnetic crystal layer It was confirmed that the mixed structure was not measured. In addition, when the temperature to be heat-treated in the reduction step is 800 ℃, it was also confirmed that the mixed structure of the Sm ₂ Co ₁₇ magnetic crystals and fcc-Co magnetic crystal layer was not measured. On the other hand, when the temperature to be heat-treated in the reduction step is 600 ℃, 700 ℃ and 750 ℃, it was confirmed that the mixed structure of the Sm ₂ Co ₁₇ magnetic crystal and fcc-Co magnetic crystal layer is easily measured.

28 is a graph showing a change in characteristics of the rare earth oxide with respect to the heat treatment temperature.

Referring to FIG. 28, the Sm ₂ O ₃ rare earth oxide is heat-treated at 25 ° C. to 1000 ° C. at a temperature increase rate of 10 ° C./mim in a hydrogen atmosphere, and then the weight loss (%) of the heat treated rare earth oxide is determined. Measured and shown. As can be seen from FIG. 28, in the case of the rare earth oxide, even when heat-treated at a temperature of 1000 ° C., there was almost no mass loss, and it was confirmed that the reduction was not easy.

29 to 31 are photographs and graphs comparing the diameters of the hybrid magnetic fibers according to Examples 1 and 3 of the present invention.

Referring to FIG. 29, a SEM image of the hybrid magnetic fiber according to Example 3 is shown in FIG. 29A, and the diameter of the hybrid magnetic fiber is measured and illustrated in FIG. 29B. As can be seen from (a) and (b) of FIG. 29, it was confirmed that the hybrid magnetic fiber according to Example 3 had a diameter of 250 nm or less and had a chain structure.

30 and 31, SEM images of the hybrid magnetic fibers according to Example 1 having a diameter of about 500 nm and a diameter of about 1000 nm are shown in FIGS. 30A and 31A, respectively. The diameters of the hybrid magnetic fibers were measured and shown in FIGS. 30B and 31B. As can be seen in FIGS. 30 and 31, the hybrid magnetic fiber according to Example 1 having a diameter of about 500 nm and a diameter of about 1000 nm has a magnetic crystal-magnetic boundary layer structure.

As mentioned above, although this invention was demonstrated in detail using the preferable embodiment, the scope of the present invention is not limited to a specific embodiment, Comprising: It should be interpreted by the attached Claim. In addition, those skilled in the art should understand that many modifications and variations are possible without departing from the scope of the present invention.

Hybrid magnetic fiber according to an embodiment of the present invention can be utilized in various industrial fields, such as permanent magnets, electric motors, micro relays, sensors.

Claims (14)

1. Preparing a source solution comprising a first source material comprising a rare earth element and a second source material comprising a transition metal element;

   Electrospinning the source solution to form preliminary hybrid magnetic fibers comprising rare earth oxides and transition metal oxides; And

   Reducing the preliminary hybrid magnetic fiber, the hybrid magnetic fiber comprising a magnetic crystal containing a compound of the rare earth element and the transition metal element, and a magnetic boundary layer containing the transition metal element Comprising a step of forming a, magnetic magnetic fiber manufacturing method.
2. According to claim 1,

   Wherein said magnetic crystal has hard-magnetic properties, and said magnetic boundary layer has soft-magnetic properties.
3. According to claim 1,

   Wherein said magnetic boundary layer comprises following magnetization behavior of said magnetic crystals.
4. According to claim 1,

   And wherein the mole fraction of the rare earth element in the source solution is greater than 9.290 at% and less than 10.562 at%.
5. According to claim 1,

   The hybrid magnetic fiber forming step,

   Mixing the preliminary hybrid magnetic fibers with a reducing agent;

   Heat-treating the preliminary hybrid magnetic fibers mixed with the reducing agent; And

   The heat-treated preliminary hybrid magnetic fibers, comprising the step of washing with a washing solution, hybrid magnetic fiber manufacturing method.
6. The method of claim 5,

   The preliminary hybrid magnetic fiber mixed with the reducing agent comprises a heat treatment at a temperature of more than 500 ℃ less than 800 ℃, hybrid magnetic fiber manufacturing method.
7. The method of claim 5,

   The reducing agent is a hybrid magnetic fiber manufacturing method comprising calcium (Ca).
8. The method of claim 5,

   The washing solution is a hybrid magnetic fiber manufacturing method comprising at least one of ammonium chloride (NH ₄ Cl), and methanol (CH ₃ OH).
9. According to claim 1,

   The source solution is a hybrid magnetic fiber manufacturing method further comprises a crystallization source containing a metal, and a viscous source containing a polymer.
10. According to claim 1,

    The rare earth element, La, Ce, Pr, Nd, Sm, or Gd, hybrid magnetic fiber manufacturing method.
11. According to claim 1,

    The transition metal element, any one of Fe, Co, or Ni, hybrid magnetic fiber manufacturing method.
12. A plurality of magnetic crystals comprising a rare earth element and a compound of a transition metal element; And

    And a magnetic boundary layer disposed between the magnetic crystals adjacent to each other, surrounding the magnetic crystals, the magnetic boundary layer comprising the transition metal element.
13. The method of claim 12,

    Wherein, in the hybrid magnetic fiber, the volume fraction of the magnetic boundary layer is greater than 0 vol% and less than 10 vol%.
14. The method of claim 12,

    The magnetic crystal has a hard magnetic property, the magnetic boundary layer has a soft magnetic property,

    Wherein said magnetic boundary layer comprises magnetization behavior of said magnetic crystals.

Images