KR102637894B1 - Plate-shaped magnetic particle with controlled magnetic anisotropy and manufacturing method thereof - Google Patents

Abstract

The present disclosure relates to magnetic particles with controlled magnetic anisotropy and an electromagnetic wave absorber containing the same. The magnetic material is manufactured in the form of plate-shaped magnetic particles by a mechanical method, heat-set, and then subjected to magnetic field heat treatment to produce shape magnetic anisotropy and uniaxial magnetic anisotropy. It is given to a magnetic material to control magnetic anisotropy. Magnetic particles with controlled magnetic anisotropy as described above have improved electromagnetic properties, and electromagnetic wave absorbers containing them are lightweight and exhibit excellent radio wave absorption ability.

Description

Plate-shaped magnetic particle with controlled magnetic anisotropy and manufacturing method thereof}

The present disclosure relates to plate-shaped magnetic particles with controlled magnetic anisotropy and a manufacturing method thereof, and also relates to an electromagnetic wave absorber containing the magnetic particles.

Magnetic materials are used in various electronic and communication devices, and because they can have both dielectric and magnetic properties, they are also used to absorb or shield electromagnetic waves. In addition, magnetic materials have a wide range of applications because they have various types and characteristics depending on the material synthesis method.

For example, electromagnetic wave absorbing materials (RAM, Radar Absorbing Materials) are used as materials that can internally absorb incident electromagnetic waves so that they are not reflected from the surface of the medium. Magnetic particles are mainly added to reinforcing materials such as polymer binders, plasticizers, and dispersants. It is often mixed and used in the form of sheets or paints.

In particular, when applied as an electromagnetic wave absorbing material to the outer shell of a specific gas, there is a disadvantage that the overall weight of the electromagnetic wave absorbing material also increases rapidly due to the high density of the magnetic material.

In addition, in the spherical magnetic material mainly used in the past, the magnetic spins within the magnetic material are randomly aligned, which deteriorates the electromagnetic properties of the magnetic material, such as electromagnetic wave absorption characteristics. Therefore, there is a need for research and development on magnetic particles that minimize the deterioration of electromagnetic properties, and by applying them to electromagnetic wave absorption materials, it is intended to have excellent radio wave absorption ability while reducing weight.

The present disclosure seeks to provide magnetic particles with improved electromagnetic properties and a method for manufacturing the same.

The present disclosure seeks to provide magnetic particles with improved electromagnetic properties and excellent radio wave absorption ability, and a lightweight electromagnetic wave absorber containing the same.

The method for manufacturing plate-shaped magnetic particles with controlled magnetic anisotropy according to the present disclosure includes the steps of manufacturing a magnetic material in the form of plate-shaped magnetic particles by a mechanical method; heat fixing the plate-shaped magnetic particles; And a step of magnetic field heat treatment of the heat-fixed plate-shaped magnetic particles.

In addition, the plate-shaped magnetic particles with controlled magnetic anisotropy according to the present disclosure are manufactured by manufacturing a magnetic material in the form of plate-shaped magnetic particles by a mechanical method, heat-setting it, and heat-treating the heat-set plate-shaped magnetic particles in a magnetic field.

In one embodiment, the plate-shaped magnetic particles may be manufactured so that the ratio of the major axis or minor axis to thickness is 1 to 100 and the length of the major axis or minor axis is 1 to 30㎛.

In one embodiment, the magnetic material includes iron (Fe), permalloy, sandust, Fe-Si-based alloy, Fe-Co-based alloy, Fe-Cr-based alloy, Fe-Cr-Si-based alloy, or any of these. It may include one or more selected from the combination.

In one embodiment, the magnetic material may have a spherical shape.

In one embodiment, the magnetic field heat treatment may be heat treatment at a temperature of 300 to 800° C. under a magnetic field of 500 to 1,500 G (gauss).

In one embodiment, the heat setting may be heat setting at a temperature of 300 to 500°C.

In one embodiment, the mechanical method includes one or more methods selected from ball milling, attrition milling, jet milling, grinding, or a combination thereof. It could be.

In one embodiment, the mechanical method may be ball milling using balls with a size of 0.1 to 2 mm at 2000 to 4000 RPM.

In one embodiment, the electromagnetic wave absorber is a lightweight electromagnetic wave absorber and includes 20 to 60 parts by weight of magnetic particles and 40 to 80 parts by weight of a matrix based on 100 parts by weight of the electromagnetic wave absorber; The magnetic particles may be plate-shaped magnetic particles with controlled magnetic anisotropy manufactured according to the present disclosure.

In one aspect of the present disclosure, it is possible to provide plate-shaped magnetic particles with controlled magnetic anisotropy that exhibit excellent electromagnetic properties and a method for manufacturing the same.

In another aspect of the present disclosure, it is possible to provide plate-shaped magnetic particles that exhibit excellent radio wave absorption ability by controlling magnetic anisotropy and a method of manufacturing the same.

In another aspect of the present disclosure, it is possible to provide a lightweight electromagnetic wave absorber that includes plate-shaped magnetic particles with controlled magnetic anisotropy according to the present disclosure and has excellent radio wave absorption ability in a high frequency band.

In another aspect of the present disclosure, an electromagnetic wave absorber containing plate-shaped magnetic particles with controlled magnetic anisotropy according to the present disclosure can be applied to provide a flying vehicle in the military and aviation fields with excellent radio wave absorption ability.

Figure 1 is a photograph comparing the shapes of the magnetic particles of Example 2 and Comparative Example 1 taken by SEM.

Hereinafter, the plate-shaped magnetic particles with controlled magnetic anisotropy of the present disclosure and their manufacturing method will be described in detail. However, this is merely illustrative and the present disclosure is not limited to the specific embodiments described by way of example.

The terms used in this disclosure are general terms that are currently widely used as much as possible while considering the function of this disclosure, but this may vary depending on the intention or precedent of a technician working in the related field, the emergence of new technology, etc. Unless otherwise defined, the technical and scientific terms used may have meanings commonly understood by those skilled in the art in the technical field to which this disclosure pertains.

In the present disclosure and the appended claims, terms such as “include” or “have” mean the presence of features or components described in the specification, and, unless specifically limited, one or more other features or This does not exclude the possibility of additional components.

As used in this disclosure and the appended claims, singular expressions include plural expressions, unless the context clearly dictates the singular. Additionally, plural expressions include singular expressions, unless the context clearly specifies plural expressions.

In addition, the numerical range used in the present disclosure includes the lower limit and the upper limit and all values within the range, the increments logically derived from the shape and width of the defined range, all doubly defined values, and the upper limit of the numerical range defined in different forms. and all possible combinations of the lower bounds. Unless otherwise specified in the present disclosure, values outside the numerical range that may occur due to experimental error or rounding of values are also included in the defined numerical range.

The term "about" or the like used in the present disclosure and appended claims is used to encompass tolerance when tolerance exists.

The method for manufacturing magnetic particles with controlled magnetic anisotropy according to the present disclosure includes the steps of manufacturing a magnetic material in the form of plate-shaped magnetic particles by a mechanical method; heat fixing the plate-shaped magnetic particles; And a step of magnetic field heat treatment of the heat-fixed plate-shaped magnetic particles.

The plate-shaped magnetic particles with controlled magnetic anisotropy according to the present disclosure are manufactured by manufacturing a magnetic material in the form of a plate-shaped magnetic particle by a mechanical method, heat-setting it, and heat-treating the heat-set plate-shaped magnetic particle in a magnetic field.

The magnetic particles with controlled magnetic anisotropy manufactured as described above have two magnetic anisotropy improvement effects: shape magnetic anisotropy and uniaxial magnetic anisotropy. Specifically, first, the magnetic material is manufactured from plate-shaped magnetic particles, and shape magnetic anisotropy is imparted, and then uniaxial magnetic anisotropy is imparted through magnetic field heat treatment. Additionally, magnetostriction of plate-shaped magnetic particles resulting from mechanical methods such as milling or grinding can be minimized through the heat setting step. From this, the magnetic particles with controlled magnetic anisotropy according to the present disclosure can have the advantage of improved electromagnetic properties.

In one embodiment, the plate-shaped magnetic particles may have a ratio of the long axis or short axis to thickness of 1 to 100, and the long axis or short axis of the plate-shaped magnetic particles may be manufactured with a length of 1 to 30㎛. In addition, the ratio of the major axis or minor axis to the thickness is 1 or more, 10 or more, 20 or more, 30 or more, 40 or more, 50 or more, 100 or less, 90 or less, 80 or less, 70 or less, 60 or less, 50 or less, or within the above range. It may be a numerical value, and the length of the major axis or minor axis may be 1 ㎛ or more, 5 ㎛ or more, 10 ㎛ or more, 15 ㎛ or more, 30 ㎛ or less, 25 ㎛ or less, 20 ㎛ or less, 15 ㎛ or less, or a value within the above range. . In the above range, the plate shape of the magnetic particles can exist evenly without being broken, and the magnetic anisotropy of the shape from the plate shape can be effectively imparted to the magnetic particles.

In one embodiment, the magnetic material includes iron (Fe), permalloy, sandust, Fe-Si-based alloy, Fe-Co-based alloy, Fe-Cr-based alloy, Fe-Cr-Si-based alloy, or any of these. It may include one or more selected from the combination. However, it is not necessarily limited to this, and any magnetic material that can be manufactured as a plate-shaped magnetic particle that achieves the physical properties of the present disclosure through mechanical compression and flaking such as milling or grinding may be used.

In one embodiment, the magnetic material may have a spherical shape. For example, the particle size (D ₅₀ ) of the spherical magnetic material is 100 ㎛ or less, 80 ㎛ or less, 60 ㎛ or less, 50 ㎛ or less, 40 ㎛ or less, 30 ㎛ or less, 1 ㎛ or more, 10 ㎛ or more, 20 ㎛ or more, or the above. It may be a value within a range, preferably 1 to 50 ㎛, 1 to 20 ㎛, or 1 to 10 ㎛.

If the particle size of the magnetic material is too small, it may break before forming a plate shape during mechanical compression, and if the particle size is too large, the yield of plate-shaped magnetic particles that satisfy the ratio of the long axis or short axis to the thickness may decrease. there is. However, as long as the physical properties of the present disclosure are achieved, the shape of the magnetic material is not necessarily limited to a spherical shape, and other types of magnetic materials can also be manufactured as plate-shaped magnetic particles that achieve the physical properties of the present disclosure through mechanical methods such as milling or grinding. If possible, that's fine.

Shape magnetic anisotropy can be imparted to the magnetic particles by compressing and flaking the magnetic material using a mechanical method to produce plate-shaped magnetic particles. Magnetic anisotropy refers to direction dependence due to the magnetic properties of magnetic particles, and this direction dependence appears depending on the direction of the magnetic moment within the magnetic particle.

For example, spherical magnetic particles have no magnetic moment directionality, so they can be randomly aligned in all directions. Therefore, the magnetization time of the internal magnetic moment of spherical magnetic particles is similar regardless of the direction of electromagnetic waves incident from the outside, and some of them are not magnetized for electromagnetic waves incident in a specific direction, thereby deteriorating the electromagnetic wave absorption characteristics in a specific direction.

When these spherical magnetic particles are compressed and flattened by mechanical methods to produce plate-shaped magnetic particles, the magnetic moment inside the magnetic particles is quickly oriented in a specific direction in response to electromagnetic waves incident in a specific direction due to the magnetic anisotropy of the plate-shaped shape. Effective magnetization is possible.

In this way, the magnetic moments of plate-shaped magnetic particles can be preferentially aligned according to a specific direction and have a larger surface area compared to spherical magnetic particles. Therefore, plate-shaped magnetic particles can have improved electromagnetic properties than before and can exhibit excellent radio wave absorption ability by effectively interacting with electromagnetic waves incident from the outside.

In addition, uniaxial magnetic anisotropy can be added by heat-treating the plate-shaped magnetic particles to which the shape magnetic anisotropy is imparted under a magnetic field. First, the plate-shaped magnetic particles align their internal magnetic moments in a specific direction due to magnetic anisotropy due to the plate shape under a magnetic field, and through heat treatment, the magnetic particles are provided with additional heat energy to achieve the target alignment of the magnetic moments in one direction. do. Due to the above-mentioned alignment, uniaxial magnetic anisotropy is imparted to the plate-shaped magnetic particles, and from this, the plate-shaped magnetic particles heat-treated under a magnetic field can have improved electromagnetic properties than before, and also have a magnetic moment along a specific axis with respect to electromagnetic waves incident from the outside. Because it is magnetized, it can effectively interact with electromagnetic waves and exhibit excellent radio wave absorption ability.

In one embodiment, the magnetic field heat treatment may be heat treatment at a temperature of 300 to 800° C. in a magnetic field of 500 to 1,500 G. In addition, the magnetic field may be 500G or more, 600G or more, 700G or more, 800G or more, 900G or more, 1000G or more, 1500G or less, 1400G or less, 1300G or less, 1200G or less, 1100G or less, or a value within the above range, and the heat treatment temperature is 300G or more. It may be ℃ or higher, 400℃ or higher, 500℃ or higher, 800℃ or lower, 700℃ or lower, or 600℃ or lower. In this way, the magnetic moment of the plate-shaped magnetic particles that have received heat energy through magnetic field heat treatment can be effectively aligned along the magnetic field direction, and magnetic anisotropy can be effectively imparted to the magnetic particles in the uniaxial direction.

In one embodiment, the heat setting may be heat setting at a temperature of 300 to 500°C. The temperature may be 300°C or higher, 400°C or higher, 500°C or lower, 400°C or lower, or a value within the above range. Magnetostriction of plate-shaped magnetic particles can be minimized through heat setting.

For example, when a magnetic material is compressed and flaked by a mechanical method such as milling or grinding, defects due to mechanical stress and grinding action may occur, which may affect the magnetostriction characteristics of the manufactured magnetic particles. For this reason, if magnetic field heat treatment is performed immediately at a high temperature without a heat setting step, physical deformation and magnetotransformation of the magnetic particles may occur during the magnetization process. Therefore, the manufactured plate-shaped magnetic particles may be heat-set and then subjected to magnetic field heat treatment to minimize physical deformation and magnetic deformation.

In one embodiment, the mechanical method includes one or more methods selected from ball milling, attrition milling, jet milling, grinding, or a combination thereof. It could be. However, it is not necessarily limited to this, and plate-shaped magnetic particles may be manufactured by compressing or pulverizing the magnetic material using other conventional milling or grinding methods used in the art, or the same or similar methods.

In one embodiment, the mechanical method may be ball milling using balls with a size of 0.1 to 2 mm at 2000 to 4000 RPM. In addition, ball milling conditions are not particularly limited as long as the physical properties of the present disclosure are achieved, but when ball milling is performed within the above range, magnetic particles that satisfy the shape anisotropy characteristics desired in the present disclosure can be manufactured with an increased yield. In addition, by adjusting the ball milling time, the ratio of the thickness to the long axis or short axis of the plate-shaped magnetic particles can be adjusted. For example, as the ball milling time increases, the magnetic particles become more flattened, resulting in a plate-shaped magnetic particle with an increased ratio of the long axis or short axis to the thickness. Magnetic particles can be manufactured. Additionally, when the ratio of the long axis or short axis to the thickness of the magnetic particle increases, further improved electromagnetic properties can be exhibited.

In one embodiment, the electromagnetic wave absorber is a lightweight electromagnetic wave absorber, and includes 20 to 60 parts by weight of magnetic particles and 40 to 80 parts by weight of a matrix based on 100 parts by weight of the electromagnetic wave absorber, and the magnetic particles are manufactured according to the present disclosure. It may be a magnetic particle with controlled magnetic anisotropy. Additionally, the magnetic particles may be included in an amount of 20 parts by weight or more, 30 parts by weight or more, 40 parts by weight or less, 60 parts by weight or less, 50 parts by weight or less, 40 parts by weight or less, or a value within the above range, and the matrix is 40 parts by weight. It may be included in more than 50 parts by weight, more than 60 parts by weight, less than 80 parts by weight, less than 70 parts by weight, less than 60 parts by weight, or within the above range.

Since the magnetic particles included in the electromagnetic wave absorber are magnetic particles with improved electromagnetic properties through controlled magnetic anisotropy, it is possible to provide a lightweight radio wave absorber that exhibits excellent radio wave absorption ability even by adding a smaller amount of magnetic particles than before. For example, it can be applied to fields such as cutting-edge electronic equipment related to electromagnetic waves.

Although not specifically limited thereto, the matrix included in the electromagnetic wave absorber may be a polymer material in which magnetic particles can be uniformly dispersed, a plasticizer, a dispersant, etc. Additionally, the electromagnetic wave absorber in which magnetic particles are uniformly dispersed in the matrix may be in the form of a paint, for example.

Examples of the matrix include polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyacrylonitrile resin, acrylonitrile-butadiene-styrene (ABS), styrene-acrylonitrile (SAN), acrylic resin, Methacrylic resin, polyamide, thermoplastic polyester (polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc.), polycarbonate, polyphenylene sulfide resin, polyamideimide, polyvinyl butyral, polyvinyl Formal, polyhydroxypolyether, polyether, polyphthalamide, fluorine-based resin (polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), etc.), phenoxy resin, polyurethane-based resin , nitrile-butadiene resin, phenol-based resin (PE), urea-based resin (UF), melamine-based resin (MF), unsaturated polyester-based resin (UP), two-component epoxy resin, styrene-butadiene rubber (SBR), poly Butadiene rubber (BR), acrylonitrile-butadiene rubber (NBR), polyisobutylene (PIB) rubber, acrylic rubber, fluorine rubber, silicone rubber, and chloroprene, and the matrix contains one or more of the above materials. You can.

Hereinafter, embodiments of the present invention will be further described with reference to specific experimental examples. The examples and comparative examples included in the experimental examples only illustrate the present invention and do not limit the scope of the appended patent claims, and various changes and modifications to the examples are possible within the scope and technical idea of the present invention. It is obvious to those skilled in the art, and it is natural that such variations and modifications fall within the scope of the appended patent claims.

First, the method of measuring physical properties in Examples and Comparative Examples was performed as follows.

1) Observation of the shape of magnetic particles using a scanning electron microscope (SEM)

The shapes of the magnetic particles in the following examples and comparative examples were observed using a SEM (Scanning Electron Microscope, Quanta FEG 650). Among the observation results, the results of comparing the shapes of the magnetic particles manufactured in Example 2 and Comparative Example 1 are shown in Figure 1.

2) Comparison of electromagnetic properties: dielectric constant and permeability measurement

What dielectric constant and permeability mean to the electromagnetic properties of magnetic particles is: First, dielectric constant is the degree to which electric dipoles formed by polarization inside a material are aligned when an external electric field is applied. It indicates that charges are accumulated through electric polarization and represents a measure of the material's ability to store charges. In addition, permeability is a coefficient that indicates the degree to which a material is magnetized in an externally given magnetic field and the degree to which magnetic flux flows. The larger the permeability value, the easier it is to magnetize the material. When the permittivity and permeability are related to the frequency of an external magnetic field, the values appear as complex numbers and are called complex permittivity and complex permeability.

Therefore, the complex permittivity and complex permeability were measured to compare the electromagnetic properties of the magnetic particles prepared in the following examples and comparative examples.

The specimen for this is a two-component epoxy resin prepared by mixing the base material (KFR-1275, Kukdo Chemical) and the hardener (KFH-5478, Kukdo Chemical) at a weight ratio of 4:1, and magnetic particles are mixed at a weight ratio of 7:3. The complex permittivity and complex permeability of the manufactured specimens were measured using a network analyzer (Agilent) and the waveguide method in the frequency range of 2 to 18 GHz. Electromagnetic properties were compared based on the results measured at a frequency of 10 GHz, which is the middle value of the above frequency range.

Hereinafter, examples and comparative examples were prepared as follows and the results of evaluation according to the physical property measurement method are described below.

[Example 1]

Spherical iron magnetic particle powder (Basf, D ₅₀ 10 μm) was ball milled into 2 mm balls at 3000 RPM for 400 hours to produce plate-shaped magnetic particles with a major axis-to-thickness ratio of 60 and a major axis length of 20 μm. At this time, the length and thickness of the long axis of 10 randomly selected magnetic particles were measured from images taken of ball-milled plate-shaped magnetic particles using a scanning electron microscope (SEM), and then the average value of the remaining values excluding the maximum and minimum values was calculated. Thus, the ratio of the major axis to the thickness and the length of the major axis were set.

The plate-shaped magnetic particles were heat-treated in a furnace at 400° C. for 1 hour to heat-set, and then a magnetic field of 1000 G was applied to produce magnetic particles with controlled magnetic anisotropy.

[Example 2]

Ball milling was performed for 200 hours to produce plate-shaped magnetic particles with a ratio of long axis to thickness of 30 and a long axis of 1㎛, and were manufactured in the same manner as in Example 1.

[Example 3]

Ball milling was performed for 96 hours to produce plate-shaped magnetic particles with a ratio of long axis to thickness of 20 and a long axis of 10㎛.

[Comparative Example 1]

Spherical iron magnetic particle powder (iron, Basf, D ₅₀ 5μm) was used as is without ball milling, heat setting, or magnetic field heat treatment.

[Comparative Example 2]

The spherical iron magnetic particle powder of Comparative Example 1 was subjected to magnetic field heat treatment under the same conditions as Example 1 without ball milling or heat setting.

Hereinafter, the physical property evaluation results of the Examples and Comparative Examples prepared as described above were compared.

First, through SEM images of the shapes of the magnetic particles manufactured in Example 2 and Comparative Example 1, the spherical shape of the iron magnetic particles of Comparative Example 1 and the plate-shaped shape of the magnetic particles with controlled magnetic anisotropy manufactured in Example 2 are shown. was able to confirm. From this, it was confirmed that, unlike Comparative Example 1, plate-shaped magnetic particles were manufactured in Example 2 through the ball milling process performed in Example 2.

Next, the complex permittivity and complex permeability measurement results measured at a frequency of 10 GHz were compared.

First, the real part value of the complex dielectric constant was higher in the examples than in the comparative examples. Specifically, when comparing the change rates of the increased real part value based on the complex dielectric constant real part value of Comparative Example 1 using spherical iron magnetic particle powder, Comparative Example 2 was about 18% and Example 3 was about 23%. , it was confirmed that the dielectric properties increased by about 56% in Example 2 and by 331% in Example 1.

In addition, the real part value of complex permeability was also higher in the examples than in the comparative examples. Specifically, when comparing the change rates of the increased real part value based on the complex permeability real part value of Comparative Example 1 using spherical iron magnetic particle powder, Comparative Example 2 was about 4% and Example 3 was about 6%. , it was confirmed that the magnetic properties increased by about 9% in Example 2 and by 11% in Example 1.

In addition, compared to Comparative Example 2 in which the same magnetic field heat treatment was performed, based on the results of a greater increase in the dielectric and magnetic properties of the examples having the shape of plate-shaped magnetic particles, the magnetic particles of Examples 1 to 3 were shaped like magnetic particles. It was found that both anisotropy and uniaxial magnetic anisotropy were controlled, resulting in excellent dielectric and magnetic properties.

Through the above evaluation, it was confirmed that the magnetic particles whose magnetic anisotropy was controlled through shape control and magnetic field heat treatment according to the present disclosure exhibited superior electromagnetic properties than conventional magnetic particles. In addition, it was confirmed that the electromagnetic wave absorber containing magnetic particles according to the present disclosure can exhibit excellent radio wave absorption ability while being lightweight.

Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments and may be implemented in various different forms, and those skilled in the art will understand the technical idea of the present invention. It will be understood that it can be implemented in other specific forms without changing the essential features. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive.

Claims (16)

Manufacturing a magnetic material in the form of plate-shaped magnetic particles by a mechanical method;
heat setting the plate-shaped magnetic particles at a temperature of 300 to 500°C; and
A method for producing plate-shaped magnetic particles having shape magnetic anisotropy and uniaxial magnetic anisotropy, comprising: magnetically heat-treating the heat-fixed plate-shaped magnetic particles at a temperature of 300 to 800° C. under a magnetic field of 500 to 1500 G (gauss). According to paragraph 1,
A method of producing plate-shaped magnetic particles having shape magnetic anisotropy and uniaxial magnetic anisotropy, wherein the plate-shaped magnetic particles are manufactured with a ratio of the major axis or minor axis to thickness of 1 to 100 and a length of the major axis or minor axis of 1 to 30 ㎛. . According to paragraph 1,
The magnetic material contains iron (Fe) and is one or more selected from permalloy, sandust, Fe-Si-based alloy, Fe-Co-based alloy, Fe-Cr-based alloy, Fe-Cr-Si-based alloy, or a combination thereof. A method for producing plate-shaped magnetic particles having shape magnetic anisotropy and uniaxial magnetic anisotropy, comprising: According to paragraph 1,
A method of manufacturing plate-shaped magnetic particles having shape magnetic anisotropy and uniaxial magnetic anisotropy, wherein the magnetic material is spherical. delete delete According to paragraph 1,
The mechanical method includes one or more methods selected from ball milling, attrition milling, jet milling, grinding, or a combination thereof. and a method for producing plate-shaped magnetic particles with uniaxial magnetic anisotropy. According to paragraph 1,
The mechanical method is a method of manufacturing plate-shaped magnetic particles having shape magnetic anisotropy and uniaxial magnetic anisotropy, which involves ball milling using balls with a size of 0.1 to 2 mm at 2000 to 4000 RPM. delete delete delete delete delete delete delete delete