Magnetic composite, and elements or components comprising a magnetic composite.

Abstract

To provide a magnetic composite that utilizes the magnetic properties based on magnetoplumbite-type hexagonal ferrite while exhibiting excellent flexibility and adhesion. Furthermore, to provide an element or component comprising the said magnetic composite. [Solution] A magnetic composite comprising a substrate and a ferrite layer provided on the surface of the substrate, wherein the ferrite layer mainly contains magnetoplumbite-type hexagonal ferrite, has a thickness of 2.0 μm or more, and in a minute-angle incident X-ray diffraction profile using Cu-Kα as a source, the ratio (A / B) of the full width at half maximum A of the (107) diffraction peak of the ferrite layer at an incident angle of 1° to the full width at half maximum B of the (107) diffraction peak of the ferrite layer at an incident angle of 5° is 0.70 or more and 0.95 or less.

Description

[Technical Field]

[0001] The present invention relates to magnetic composites, and elements or components comprising magnetic composites. [Background technology]

[0002] Magnetoplanbite-type hexagonal ferrites, such as Sr ferrite and Ba ferrite (hereinafter sometimes collectively referred to as "M-type ferrites"), are hard magnetic materials with high magnetic anisotropy and coercivity, and are widely used in permanent magnet applications. Furthermore, they can achieve high magnetic resonance frequencies beyond the Sneak limit, and are expected to be applied to electromagnetic wave absorbers in the high-frequency range.

[0003] It has been proposed to prepare a paint by mixing a hard magnetic material such as M-type ferrite with a resin and a solvent, and then to apply the resulting paint to a substrate to create a magnetic composite consisting of a substrate and a magnetic layer.

[0004] For example, Patent Document 1 describes a flexible magnet sheet in which a coating is formed by mixing and dispersing ferromagnetic material powder with a binder such as resin, applying the coating to a substrate to form a coating film, and then magnetizing one or both sides of the coated object. It states that ferromagnetic material powders such as BaO·6Fe2O3 and SrO·6Fe2O3 can be used, that thin films can be easily made and variations in film thickness can be kept small, and that it can be applied to a wide range of applications such as magnets for linear motors, magnets for encoders, magnetic sensors, and switches (Claim 1,

[0011] ,

[0076] and

[0077] ).

[0005] Patent Document 2 describes the composition formula AFe (12-x) Al x O 19However, a radio wave absorber is disclosed in which A is one or more of Sr, Ba, Ca, and Pb, and x: 1.0 to 2.2, and the peak particle size of the laser diffraction scattering particle size distribution is 10 μm or more. (Claim 1) Furthermore, Patent Document 2 states that a radio wave absorber exhibiting excellent radio wave absorption performance around 76 GHz can also be constructed by mixing the above-mentioned magnetoplanbite-type hexagonal ferrite powder into a paint and applying it to the surface of a substrate (Paragraph

[0031] ). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 11-273938 [Patent Document 2] Japanese Patent Publication No. 2007-250823 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] As described above, magnetic composites consisting of a magnetic layer containing M-type ferrite and a substrate have been proposed conventionally. However, the inventors' research has revealed that there is room for improvement in the conventional technology. Specifically, the magnetic composites disclosed in Patent Documents 1 and 2, which are made by coating a substrate with an M-type ferrite-containing paint, have limitations in improving magnetic properties because the ferrite layer (magnetic layer) contains a large amount of resin, which is a non-magnetic component. Furthermore, problems were found in terms of flexibility and adhesion.

[0008] As a result of further investigation by the inventors, it was found that in a magnetic composite comprising a ferrite layer mainly composed of M-type hexagonal ferrite exhibiting hard magnetic properties and a substrate, the peak full width at half maximum ratio in the minute-angle incident X-ray diffraction profile is important, and by controlling this peak full width at half maximum ratio, it is possible to obtain a magnetic composite with excellent flexibility and adhesion while utilizing the magnetic properties based on M-type ferrite.

[0009] This invention was completed based on such findings, and aims to provide a magnetic composite with excellent flexibility and adhesion while utilizing the magnetic properties based on magnetoplumbite-type hexagonal ferrite (M-type ferrite). Furthermore, this invention also aims to provide an element equipped with the said magnetic composite. [Means for solving the problem]

[0010] The present invention encompasses the following embodiments (1) to (7). In this specification, the expression "~" includes the values ​​at both ends. That is, "X~Y" is synonymous with "X or greater and Y or less".

[0011] (1) A magnetic composite comprising a substrate and a ferrite layer provided on the surface of the substrate, The ferrite layer mainly consists of magnetoplumbite-type hexagonal ferrite, has a thickness of 2.0 μm or more, and in a small-angle incident X-ray diffraction profile using Cu-Kα as a source, the ratio (A / B) of the full width at half maximum A of the (107) diffraction peak of the ferrite layer at an incident angle of 1° to the full width at half maximum B of the (107) diffraction peak of the ferrite layer at an incident angle of 5° is 0.70 or more and 0.95 or less, in a magnetic composite.

[0012] (2) The magnetic composite of (1) above, wherein the ferrite layer comprises at least one or both of strontium (Sr) and barium (Ba), iron (Fe), and oxygen (O).

[0013] (3) Thickness of the base material (d S A magnetic composite of the above (1) or (2), wherein the diameter is 10.0 μm or larger.

[0014] (4) Any of the magnetic composites described in (1) to (3) above, wherein the arithmetic mean roughness (Ra) of the surface of the ferrite layer is 0.10 μm or more and 0.30 μm or less.

[0015] (5) The surface resistance of the ferrite layer is 1.0 × 10 5 A magnetic composite of any of the above (1) to (4) having a capacitance of Ω or greater.

[0016] (6) An element or component comprising any one of the magnetic composites of (1) to (5) above.

[0017] (7) The element or component of (6) above, which is at least one selected from the group consisting of an electromagnetic noise absorber, an antenna, a sensor, an actuator, and a motor.

Advantages of the Invention

[0018] According to the present invention, there is provided a magnetic composite excellent in flexibility and adhesion while making use of magnetic properties based on magnetoplumbite-type hexagonal ferrite. Further, according to the present invention, there is provided an element or component comprising the magnetic composite.

Brief Description of the Drawings

[0019] [Figure 1] Shows the state of reflection and refraction of X-rays in micro-angle XRD. [Figure 2] Shows one aspect of the magnetic composite. [Figure 3] Shows another aspect of the magnetic composite. [Figure 4] Shows another aspect of the magnetic composite. [Figure 5] Shows still another aspect of the magnetic composite. [Figure 6] Shows an example of the configuration of an aerosol deposition film-forming apparatus. [Figure 7] Shows an example of the X-ray diffraction profiles of a substrate, ferrite powder, and ferrite layer.

Modes for Carrying Out the Invention

[0020] Specific embodiments of the present invention (hereinafter referred to as "these embodiments") are described below. However, the present invention is not limited to the following embodiments, and various modifications are possible without altering the essence of the invention. Furthermore, in this specification, any combination of preferred embodiments can be adopted as long as technical consistency can be maintained. For example, one of the preferred numerical ranges can be arbitrarily combined with the other.

[0021] <<1.Magnetic composite>> The magnetic composite of this embodiment comprises a substrate and a ferrite layer provided on the surface of the substrate. The ferrite layer mainly contains magnetoplumbite-type hexagonal ferrite and has a thickness of 2.0 μm or more. Furthermore, in the small-angle incident X-ray diffraction profile using Cu-Kα as a source, the ratio (A / B) of the full width at half maximum (FWHM) B of the (107) diffraction peak of the ferrite layer at an incident angle of 5° to the full width at half maximum (FWHM) A of the (107) diffraction peak of the ferrite layer at an incident angle of 1° is 0.70 or more and 0.95 or less. The magnetic composite will be described in detail below.

[0022] <Base material> The substrate functions as a support for the ferrite layer. As long as it functions as a support, the shape of the substrate is not limited. For example, it may be in the shape of a plate, sheet, foil, rod, box, thread, or strip. The material of the substrate is also not limited. Examples include resin, metal, ceramic, glass, cloth, or a combination thereof. However, it is preferable that the substrate is composed of either metal or resin, or both.

[0023] When the substrate is made of metal, conductivity can be imparted to the substrate. Therefore, the substrate can be used for applications such as electrodes. Furthermore, when a magnetic composite is used as an electromagnetic wave absorber (electromagnetic noise absorber), the metal substrate can function as an electromagnetic wave reflector. That is, when the ferrite layer of the magnetic composite is oriented towards the electromagnetic wave incidence side, a portion of the electromagnetic wave is incident on the ferrite layer. The intensity of the incident electromagnetic wave is attenuated as it passes through the ferrite layer. The attenuated electromagnetic wave is reflected by the surface of the metal substrate, passes through the ferrite layer again, and is radiated from its surface.

[0024] The composition of the metal constituting the metal substrate is not limited. It may be a single metal or an alloy. Preferably, the metal is at least one selected from the group consisting of copper (Cu), aluminum (Al), nickel (Ni), iron (Fe), cobalt (Co), chromium (Cr), gold (Au), and silver (Ag).

[0025] The metal substrate may consist solely of metal, or it may be a laminate of a non-metallic substrate and a metal layer. In this case, the metal layer laminated on the non-metallic substrate corresponds to the metal substrate. A resin film such as PET film can be used as the non-metallic substrate. As the metal layer, one formed on the non-metallic substrate by a thin-film formation method may be used.

[0026] When the base material is made of resin, the resin base material may be in the form of a plate or a sheet. However, it is preferably in the form of a sheet. By using a sheet-shaped resin base material (resin sheet), a magnetic composite with excellent flexibility can be made. The resin that makes up the resin base material is not particularly limited. It may be a single resin, or it may be a mixture or copolymer of two or more types of resins. Preferably, the resin is at least one selected from the group consisting of polycarbonate (PC), polyimide (PI), polyvinyl chloride (PVC), polyoxymethylene (POM), acrylonitrile butadiene styrene (ABS), polyether ether ketone (PEEK), and polyamide (PA). These resins have excellent mechanical strength and excellent insulating properties.

[0027] Preferably, the thickness (d S ) of the base material is 10.0 μm or more. If the base material is excessively thin, it becomes difficult to impart sufficient mechanical strength. From the viewpoint of enhancing mechanical strength, the base material thickness (d S ) is more preferably 25.0 μm or more, and even more preferably 50.0 μm or more. The upper limit of the base material thickness is not limited. However, by appropriately suppressing the thickness, it becomes possible to give flexibility to the magnetic composite. Therefore, for example, the magnetic composite can be applied to the curved surface of a device having a curved surface. The base material thickness may be 5000 μm or less, 2000 μm or less, or 1000 μm or less.

[0028] <Ferrite layer> In the magnetic composite of the present embodiment, the ferrite layer provided on the base material is the main body for expressing magnetic properties. The ferrite layer contains a magnetoplumbite-type hexagonal ferrite (M-type ferrite) as a main component. M-type ferrite has a basic composition represented by the general formula AFe 12 O 19 (where A is a divalent metal such as Ba, Sr, Ca, and / or Pb), and has the characteristics of having a large magnetic anisotropy and exhibiting excellent hard magnetic properties. Therefore, it is widely used in applications of permanent magnets that can generate a strong magnetic force (magnetic flux) externally without requiring electric power. In addition, since M-type ferrite has a large magnetic anisotropy, it has a high magnetic resonance frequency, and it is expected to exhibit electromagnetic wave absorption performance in the high-frequency range by making use of this feature.

[0029] Furthermore, the M-type ferrite in this embodiment may be a ferrite in which a portion of the divalent metal element A (Sr, Ba, Ca, Pb, etc.) in the above-described composition formula is replaced with other metal elements such as lanthanum (La), neodymium (Nd), and / or samarium (Sm). Alternatively, it may be a ferrite in which a portion of iron (Fe) is replaced with other metal elements such as aluminum (Al), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), zirconium (Zr), and / or tin (Sn). Moreover, it is not limited to a ferrite where the atomic ratio of the A-site element to the Fe-site element is strictly "12". As long as the crystal structure of magnetoplumbite-type hexagonal ferrite is maintained, deviations in composition are acceptable.

[0030] In this specification, the main component refers to a component with a content of 50.0% by mass or more. From the viewpoint of utilizing the magnetic properties based on M-type ferrite, the content of M-type ferrite in the ferrite layer is preferably 60.0% by mass or more, more preferably 70.0% by mass or more, even more preferably 80.0% by mass or more, particularly preferably 90.0% by mass or more, and most preferably 95.0% by mass or more. The ferrite layer may also contain components other than ferrite. Examples of such components include α-Fe2O3.

[0031] The ferrite layer of this embodiment preferably contains at least one or both of strontium (Sr) and barium (Ba), iron (Fe), and oxygen (O). That is, it is preferable that the M-type ferrite has a composition of Sr ferrite and / or Ba ferrite. A ferrite layer having such a composition has excellent shielding properties (electromagnetic wave absorption properties) as a magnetic material in the high-frequency range including the millimeter wave band.

[0032] The thickness of the ferrite layer in this embodiment (d FThe thickness is 2.0 μm or more. If the thickness is less than 2.0 μm, the thickness of the ferrite layer is likely to become non-uniform, which may reduce the film strength. In addition, this tends to lead to a decrease in magnetic properties. From the viewpoint of improving film strength and magnetic properties, a thickness of 5.0 μm or more is preferable, and 10.0 μm or more is more preferable. There is no upper limit to the thickness. However, it is difficult to deposit an excessively thick ferrite layer while maintaining its density. Also, if the ferrite layer is excessively thick, the internal stress of the ferrite layer becomes too large, which may cause the ferrite layer to peel off. In particular, when imparting flexibility to a magnetic composite, it is desirable for the ferrite layer to be moderately thin. A thickness of 100.0 μm or less is preferable, 50.0 μm or less is more preferable, and 20.0 μm or less is even more preferable. From the viewpoint of achieving both improved film strength and magnetic properties and the imparting of flexibility, the thickness is preferably 2.0 μm to 100.0 μm, more preferably 2.0 μm to 50.0 μm, and even more preferably 2.0 μm to 20.0 μm. Furthermore, although this embodiment does not exclude the case in which other layers are interposed between the ferrite layer and the substrate, it is preferable that no other layers are interposed between the ferrite layer and the substrate, that is, that the ferrite layer is directly provided on the surface of the substrate.

[0033] Note that the thickness (d F ) is the total thickness of the ferrite layer provided on the substrate. When the ferrite layer is provided on only one of the front or back surfaces of the substrate, the thickness of that ferrite layer is d F This corresponds to d. When ferrite layers are provided on both the front and back surfaces of the substrate, the sum of the thicknesses of the respective ferrite layers is d F It corresponds to this.

[0034] Furthermore, if the substrate is a laminate composed of multiple layers, the thickness of the layer in direct contact with the ferrite layer corresponds to the substrate thickness. If the substrate has irregularities, the arithmetic mean of the thinnest and thickest parts of the substrate where the ferrite layer is formed is the substrate thickness d. S The arithmetic mean of the thinnest and thickest parts of the composite and the thickness d of the substrate are used. S The difference is the thickness d of the ferrite layer. FIf ferrite layers are formed on both sides of the composite, the arithmetic mean of the thinnest and thickest parts of the composite and the thickness d of the substrate are used. S The difference is the thickness d of the ferrite layer. F It is assumed that, in other words, if ferrite layers of the same thickness are formed on both sides of the substrate, then twice the thickness of the ferrite layer on one side is considered to be d. F It corresponds to this.

[0035] In this embodiment, the ferrite layer exhibits a ratio (A / B) of 0.70 to 0.95 in the small-angle incident X-ray diffraction (XRD) profile using Cu-Kα as a source, where A is the full width at half maximum (FMAX) of the (107) diffraction peak of the ferrite layer at an incident angle of 1° and B is the full width at half maximum (FMAX) of the (107) diffraction peak of the ferrite layer at an incident angle of 5°. Here, the (107) diffraction peak is the diffraction peak corresponding to the (107) plane of the M-type ferrite contained in the ferrite layer. In other words, when small-angle incident X-ray diffraction analysis is performed on the ferrite layer, the ratio (A / B) of 0.70 to 0.95 in the XRD profile obtained under the condition of an incident angle of 1° and 0.70 to 0.95 in the XRD profile obtained under the condition of an incident angle of 5° is 0.70 to 0.95. The ferrite layer (107) diffraction peak appears near 2θ=32° in the XRD profile obtained using Cu-Kα as a source.

[0036] Figure 1 shows the reflection and refraction of X-rays in micro-angle X-ray diffraction (XRD). In micro-angle XRD analysis, X-rays are irradiated onto the sample at a small incident angle. In this case, the X-rays only penetrate near the surface of the sample. Therefore, micro-angle XRD has the characteristic of being able to analyze the region near the sample surface with high sensitivity. In this embodiment, the ratio of the full width at half maximum A of the main peak from the ferrite layer obtained when measured under an incident angle of 1° to the full width at half maximum B of the main peak obtained when measured under an incident angle of 5° is used as an index. The XRD profile obtained under a small incident angle (1°) contains only crystal information from a very shallow region near the surface of the ferrite layer, while the XRD profile obtained under a large incident angle (5°) also contains crystal information from the interior. By comparing the crystal information of the surface and the interior, the crystallinity of the ferrite layer can be evaluated with higher accuracy.

[0037] By limiting the ratio A / B to a predetermined range, the adhesion between the ferrite layer and the substrate can be improved, the film strength of the ferrite layer can be increased, and the flexibility of the magnetic composite can be further enhanced. Conversely, if the ratio A / B is less than 0.70 or greater than 0.95, the adhesion and flexibility will decrease. This is thought to be because if the ratio A / B is less than 0.70, the balance of the crystallinity distribution within the ferrite layer (crystallinity distribution from the vicinity of the substrate toward the surface) is disrupted, and if the ratio A / B is greater than 0.95, the crystallinity distribution within the ferrite layer almost disappears. A ratio A / B of 0.75 or more and 0.90 or less is preferable, and 0.80 or more and 0.90 or less is more preferable.

[0038] Preferably, the ferrite layer has an arithmetic mean roughness (Ra) of 0.10 μm or more and 0.30 μm or less. By appropriately controlling the surface Ra, the thickness of the ferrite layer can be made uniform. Conversely, if the Ra is excessively large, the thickness of the ferrite layer may become non-uniform. If the thickness is non-uniform, the electric field may concentrate locally when a high voltage is applied, which may cause leakage current to occur. Ra is more preferably 0.10 μm or more and 0.25 μm or less, and even more preferably 0.10 μm or more and 0.20 μm or less.

[0039] Preferably, the ferrite layer has a surface resistance of 1.0 × 10⁻⁶ 5 It is greater than Ω. Surface resistance depends on the resistance of the raw material powder. By increasing the surface resistance, the insulating properties of the ferrite layer can be improved. Therefore, when magnetic composites are applied to devices, problems such as eddy current generation can be suppressed. From the perspective of improving insulating properties, the surface resistance should be 1.0 × 10⁻⁶. 6 Ω or greater is more preferable, 1.0 × 10 8 A value of Ω or more is even more preferable, and 1.0 × 10 10 A resistance of Ω or greater is particularly preferred. There is no upper limit to the surface resistance. However, for example, 1.0 × 10⁻⁶ 12 It can be less than or equal to Ω.

[0040] Preferably, the adhesion strength between the ferrite layer and the substrate is H or higher on the pencil hardness scale. Here, the adhesion strength on the pencil hardness scale is the maximum hardness at which peeling of the ferrite layer is not observed when evaluated using a pencil hardness test (pencil scratch test) in accordance with the old JIS K5400. Pencil hardness increases in the order of 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, 6H, 7H, 8H, 9H, and 10H, and higher hardness indicates better adhesion. By increasing the adhesion strength, peeling of the ferrite layer when using magnetic composites can be suppressed. An adhesion strength of 5H or higher is more preferable, 6H or higher is even more preferable, 7H or higher is particularly preferable, and 8H or higher is most preferable.

[0041] Preferably, the ferrite layer contains ferrite components, with the remainder being unavoidable impurities. That is, it is preferable that it does not contain organic or inorganic components other than ferrite components in amounts exceeding the amount of unavoidable impurities. Here, ferrite components refer to the components that make up the main component, M-type ferrite. For example, if the ferrite layer is mainly composed of Sr ferrite, the ferrite components are strontium (Sr), iron (Fe), and oxygen (O). Also, if the ferrite layer is mainly composed of Ba ferrite, the ferrite components are barium (Ba), iron (Fe), and oxygen (O). Furthermore, unavoidable impurities are components that are inevitably mixed in during manufacturing, and their content is typically 1000 ppm or less. It is preferable that the ferrite layer does not contain components other than oxides, such as resin components.

[0042] The ferrite layer of this embodiment can be sufficiently densified even without containing resin components such as binders and / or inorganic additives such as sintering aids. By minimizing the content of nonmagnetic resin components and inorganic additives, the magnetic properties based on ferrite can be fully utilized.

[0043] The form of the magnetic composite is not particularly limited. As shown in Figure 2, the ferrite layer (ferrite film) may be provided on the entire surface of the substrate. As shown in Figure 3, the ferrite layer may be provided on only a part of the surface of the substrate. The ferrite layer may be provided on both sides of the substrate, not just one side. As shown in Figure 4, the ferrite layer with partially varying thickness may be provided on the surface of the resin substrate. Furthermore, as shown in Figure 5, the ferrite layer may be wrapped around the outer circumference of a rod-shaped resin substrate.

[0044] The magnetic composite of this embodiment is highly reliable and can be used stably for a long period of time. Such advantages make the magnetic composite applicable to a variety of applications. Examples of such applications include electromagnetic noise absorbers, antennas, sensors, actuators, and / or motors incorporating the magnetic composite.

[0045] <<2. Method for Manufacturing Magnetic Composites>> The manufacturing method of the magnetic composite of this embodiment is not limited as long as the above requirements are satisfied. However, a preferred manufacturing method comprises the following steps: a step of preparing a substrate and magnetoplanbite-type hexagonal ferrite powder (film-forming raw material powder; M-type ferrite powder) having an average particle size (D50) of 2.5 μm or more and 10.0 μm or less (preparation step); and a step of forming a film of this ferrite powder on the surface of the substrate by aerosol deposition (film-forming step).

[0046] Thus, by using ferrite powder with a specific particle size as a raw material and performing film formation using the aerosol deposition method (AD method), it is possible to produce a relatively thick ferrite layer at a high film formation rate while suppressing the aggregation of the raw material powder in the aerosolization chamber. This ferrite layer is dense, has excellent properties such as electrical insulation, and exhibits excellent adhesion to the substrate. Therefore, it is suitable as a method for manufacturing magnetic composites. Each step will be described in detail below.

[0047] <Preparation process> In the preparation step, the substrate and M-type ferrite powder (film-forming raw material powder) are prepared. Details of the substrate are as described above. Meanwhile, as the film-forming raw material powder, ferrite powder with an average particle size (D50) of 2.5 μm or more and 10.0 μm or less is prepared. Preferably, the average particle size is 2.5 μm or more and 7.0 μm or less. By adjusting the average particle size within the above range, a dense ferrite layer with high adhesion can be obtained in the subsequent film-forming step.

[0048] The method for producing ferrite powder (film-forming raw material powder) is not limited. However, preferably, a ferrite raw material mixture is calcined in an atmospheric environment to produce a calcined product, and the resulting calcined product is pulverized to produce irregularly shaped particles of a specific particle size. Alternatively, the ferrite raw material mixture may be subjected to calcination, pulverization, and / or granulation treatment before calcination. Known ferrite raw materials such as oxides, carbonates, and hydroxides may be used as the ferrite raw material.

[0049] When calcination is performed during the preparation of ferrite powder, for example, it should be done under conditions of 600-1200°C for 1-24 hours in an air atmosphere. When main calcination is performed, for example, it should be done under conditions of 800-1350°C for 4-24 hours in an air atmosphere.

[0050] The calcined material is preferably crushed using a grinder such as a dry bead mill. Dry grinding provides mechanochemical treatment to the calcined material, reducing the crystallite size and increasing its surface activity. The highly surface-active pulverized powder, combined with the effect of an appropriate particle size, contributes to the densification of the ferrite layer obtained in the subsequent film formation process.

[0051] <Film formation process> In the film formation process (deposition process), ferrite powder (film formation raw material powder) is deposited on the surface of the substrate using the aerosol deposition method (AD method) to form a ferrite layer. The aerosol deposition method (AD method) is a technique in which aerosolized raw material fine particles are sprayed onto the substrate at high speed, and a film is formed by the room-temperature impact solidification phenomenon. Because it utilizes the room-temperature impact solidification phenomenon, it is possible to form a dense film with high adhesion. Furthermore, since fine particles are used as the raw material, it is possible to obtain a thick film at a high film formation rate compared to thin film formation methods such as sputtering and vapor deposition, which separate the raw material to the atomic level. In addition, because film formation is possible at room temperature, there is no need to make the equipment configuration complex, which also has the effect of reducing manufacturing costs.

[0052] Figure 6 shows an example of the configuration of an aerosol deposition apparatus. The aerosol deposition apparatus (20) comprises an aerosolization chamber (2), a deposition chamber (4), a transport gas source (6), and a vacuum exhaust system (8). The aerosolization chamber (2) comprises a vibrator (10) and a raw material container (12) placed on top of it. Inside the deposition chamber (4) are a nozzle (14) and a stage (16). The stage (16) is configured to move perpendicular to the spray direction of the nozzle (14).

[0053] During film formation, a transport gas is introduced from a transport gas source (6) into a raw material container (12), and a vibrator (10) is activated. The raw material container (12) is filled with raw material fine particles (film formation raw material powder). The vibration mixes the raw material fine particles with the transport gas and aerosolizes them. The film formation chamber (4) is also evacuated by a vacuum exhaust system (8), reducing the pressure inside the chamber. The aerosolized raw material fine particles are transported into the film formation chamber (4) due to the pressure difference and ejected from a nozzle (14). The ejected raw material fine particles collide with the surface of a substrate (base material) placed on a stage (16) and deposit there. At this time, the kinetic energy of the raw material fine particles, which have been accelerated by gas transport, is locally released upon collision with the substrate, realizing substrate-particle and particle-particle bonding. This makes it possible to form a dense film. By moving the stage (16) during film formation, it becomes possible to form a film with expansion in the planar direction.

[0054] The reason why a dense ferrite layer can be obtained with the manufacturing method of this embodiment is as follows: Ceramics are generally said to be materials with a high elastic limit and that are difficult to plastically deform. However, when raw material nanoparticles collide with the substrate at high speed during film formation by the aerodeposition method, a large impact force is generated that exceeds the elastic limit, so we believe that the nanoparticles undergo plastic deformation. Specifically, defects such as crystal plane displacement and dislocation movement occur inside the nanoparticles, and in order to compensate for these defects, plastic deformation occurs and the crystal structure becomes finer. In addition, new surfaces are formed and mass transfer occurs. As a result of the combined action of these factors, we believe that the bonding force between the substrate and particles, and between particles themselves, is increased, resulting in a dense film. Furthermore, we believe that a portion of the ferrite is decomposed and reoxidized during plastic deformation, contributing to increased resistance. We also speculate that nanoparticles that collide with the substrate in the initial stage of film formation penetrate into the substrate, and these penetrating nanoparticles exhibit an anchoring effect, thereby increasing the adhesion between the ferrite layer and the substrate.

[0055] The average particle size of the raw ferrite powder is important for obtaining a dense ferrite layer. In this embodiment, the average particle size (D50) of the ferrite powder is limited to 2.5 μm or more and 10.0 μm or less. If the average particle size is less than 2.5 μm, it becomes difficult to obtain a dense film. This is because powders with a small average particle size have small particle masses. Aerosolized raw material fine particles collide with the substrate at high speed along with the transport gas. The transport gas that collides with the substrate changes direction and flows as exhaust gas. Particles with small particle size and small mass are swept away by the exhaust flow of the transport gas, resulting in a small collision velocity with the substrate surface and a small impact force. If the impact force is small, the plastic deformation received by the fine particles is insufficient, and the crystallite size does not decrease. The deposited film does not become dense, and becomes a compacted powder that is merely compressed powder. Such compacted powders contain many pores and have inferior magnetic and electrical properties. Moreover, the adhesion to the substrate is not high. On the other hand, if the average particle size exceeds 10.0 μm and is excessively large, the impact force on a single particle is large, but the number of contact points between particles decreases. As a result, plastic deformation and packing become insufficient, making it difficult to obtain a dense film.

[0056] The film deposition conditions for the aerosol deposition method are not particularly limited, as long as a dense ferrite layer with high adhesion can be obtained. Air or inert gases (nitrogen, argon, helium, etc.) can be used as the transport gas. However, air is preferred because it is easy to handle.

[0057] As long as the desired magnetic composite can be obtained, the flow rate of the transport gas is not limited. However, by changing the gas flow rate, it is possible to control the surface resistance and film thickness of the ferrite layer. Even with the same composition, making plastic deformation more likely during film formation makes the fine particles constituting the ferrite layer more susceptible to oxidation. We believe that these oxidized fine particles can be used to increase resistance while minimizing the degradation of magnetic properties.

[0058] The gas flow rate is preferably 5.0 L / min or more, more preferably 7.5 L / min or more, and even more preferably 10.0 L / min or more. If the transport gas flow rate is too low, the energy of the raw material particles upon impact with the substrate is low, and the plastic deformation of the raw material particles does not occur sufficiently during film formation. As a result, the crystallinity of the raw material particles remains, and the full width at half maximum (FWHM) of the X-ray diffraction lines of the resulting ferrite layer becomes small. If the transport gas flow rate is too high, the plastic deformation of the raw material particles occurs sufficiently during film formation, but oxidation occurs more than necessary during plastic deformation. As a portion of the ferrite layer becomes oxide, the full width at half maximum (FWHM) of the X-ray diffraction lines of the resulting ferrite layer becomes large. A transport gas flow rate of 20.0 L / min or less is desirable.

[0059] The internal pressure of the film deposition chamber may be, for example, 10-50 Pa before film deposition and 50-400 Pa during film deposition.

[0060] The scanning speed (movement speed) of the substrate (stage) may be, for example, 1.0 to 20.0 mm / second. The arithmetic mean roughness (Ra) of the ferrite layer surface depends on the scanning speed (movement speed) of the substrate (stage). By controlling the scanning speed, the surface Ra can be adjusted to an appropriate range, thereby making it possible to obtain a magnetic composite with excellent reading performance.

[0061] Furthermore, the coating (film formation) may be performed only once or multiple times, as long as the desired film thickness is achieved. However, if the ferrite layer thickness is excessively small, it may be difficult to obtain the desired peak width at half maximum (A / B) in the small-angle incident XRD profile. The number of coatings is, for example, 5 to 100 times, preferably 15 or more times.

[0062] <Magnetization process> If necessary, a magnetization process may be performed by applying a strong magnetic field to the ferrite layer deposited on the substrate. By magnetizing, the direction of the magnetic moments in the ferrite layer is aligned, thereby generating a strong magnetic force (magnetic flux) externally. Therefore, when using the magnetic composite for permanent magnet applications, it is desirable to include a magnetization process.

[0063] In this way, the magnetic composite of this embodiment can be obtained. In the obtained magnetic composite, the ferrite layer has excellent properties such as electrical insulation. It also has high adhesion to the substrate. In fact, the inventors have succeeded in fabricating a magnetic composite with a ferrite layer having an adhesion strength of 6H to 8H on the pencil hardness scale. Moreover, although not limited to such composites, a magnetic composite with a thinned substrate is flexible, making it possible to fabricate devices with complex shapes.

[0064] <<3. Elements or Components>> The element or component of this embodiment comprises the magnetic composite described above. Because this element or component includes an M-type ferrite layer exhibiting excellent hard magnetic properties, it is suitable for known applications where permanent magnets are used. Furthermore, it is expected to exhibit high magnetic resonance frequencies and electromagnetic wave absorption performance in the high-frequency range. As an element or component having such characteristics, at least one selected from the group consisting of electromagnetic noise absorbers, antennas, sensors, actuators, and motors is preferred. [Examples]

[0065] The present invention will be described in more detail using the following examples. However, the present invention is not limited to the following examples.

[0066] (1) Fabrication of magnetic composites [Example 1] In Example 1, a ferrite powder mainly composed of Sr-based ferrite was prepared, and the obtained ferrite powder was deposited on a polyimide substrate to create a magnetic composite. The preparation of the ferrite powder and the deposition of the film were carried out according to the following procedure.

[0067] <Preparation of ferrite powder> Iron oxide (Fe2O3) and strontium carbonate (SrCO3) were prepared as raw materials and mixed in a molar ratio of Fe2O3:SrCO3 = 5.75:1.0. The mixing was performed using a Henschel mixer. Next, the resulting mixture was ground for 4.5 hours using a dry media mill (a vibratory mill equipped with 1 / 8-inch diameter stainless steel beads), and the resulting pulverized material was pelletized using a roller compactor to obtain pellets of approximately 1 mm square.

[0068] The coarse powder was removed from the obtained pellets using a vibrating sieve with a mesh size of 3 mm, and then the fine powder was removed using a vibrating sieve with a mesh size of 0.5 mm. The pellets from which the coarse and fine powders had been removed were subjected to pre-sintering by heating in a rotary electric furnace at 1080°C in air for 3 hours to obtain a pre-sintered body.

[0069] The obtained pre-sintered body was pulverized using a dry media mill (vibrating mill equipped with 1 / 8-inch diameter stainless steel beads) until the volume-average particle size was approximately 4 μm. Then, water was added, and the material was further pulverized for 10 hours using a wet media mill (vertical bead mill equipped with 1 / 16-inch diameter stainless steel beads). An aqueous solution of polyvinyl alcohol (PVA) (20% by mass solution) was added to the resulting pulverized material as a binder to obtain a slurry. The solid content concentration in the slurry was 55.0% by mass, and the binder content was 1.0% by mass. The obtained slurry was spray-dried using a spray dryer to obtain granules.

[0070] The obtained granules were subjected to particle size adjustment, and then the binder was removed by heating them in a rotary electric furnace at 650°C for 2 hours. The binder-removed granules were then calcined in a fixed electric furnace at 1185°C in air for 4 hours to produce calcined material. Next, the resulting calcined material was pulverized using a dry bead mill equipped with 3 / 16-inch diameter steel ball beads to obtain pulverized calcined material.

[0071] <Film formation> A ferrite layer was deposited on the surface of a resin substrate using the obtained pulverized and calcined material. A 125 μm thick polyimide film was used as the substrate. The film deposition was carried out by the aerosol deposition method (AD method) under the following conditions.

[0072] - Carrier gas: Air - Gas flow rate: 10.0 L / min - Pressure inside the deposition chamber (before deposition): 30 Pa - Pressure inside the deposition chamber (during deposition): 200 Pa - Board scanning speed: 10 mm / second - Number of coatings: 10 times (one side) - Distance from substrate to nozzle: 20 mm - Nozzle shape: 10mm x 0.4mm

[0073] [Example 2] In Example 2, the number of coatings during film formation was changed from 10 to 20. Otherwise, the magnetic composite was fabricated in the same manner as in Example 1.

[0074] [Example 3] In Example 3, the number of coatings during film formation was changed from 10 to 30. Otherwise, the magnetic composite was fabricated in the same manner as in Example 1.

[0075] [Example 4] In Example 4, the number of coatings during film formation was changed from 10 to 40. Otherwise, the magnetic composite was fabricated in the same manner as in Example 1.

[0076] [Example 5] In Example 5, the gas flow rate during film deposition was changed from 10.0 L / min to 5.0 L / min. Otherwise, the magnetic composite was fabricated in the same manner as in Example 1.

[0077] [Example 6] In Example 6, the gas flow rate during film deposition was changed from 10.0 L / min to 20.0 L / min. Otherwise, the magnetic composite was fabricated in the same manner as in Example 1.

[0078] [Example 7] In Example 7, the substrate was changed to a copper foil with a thickness of 50 μm. Otherwise, the magnetic composite was fabricated in the same manner as in Example 1.

[0079] [Example 8] In Example 8, the substrate was changed to a copper foil with a thickness of 50 μm. Also, the number of coatings during film formation was changed from 10 to 40. Otherwise, the magnetic composite was fabricated in the same manner as in Example 1.

[0080] [Example 9 (Comparative Example)] In Example 9, the ferrite powder obtained in Example 1 was kneaded with PVA, and the resulting mixture was molded to produce a resin sheet with a thickness of 500 μm. During kneading, the amount of ferrite powder was 90% by mass relative to the PVA.

[0081] [Example 10 (Comparative Example)] In Example 10, the pulverized and calcined material was further pulverized using a wet-type bead mill, and a ferrite layer was formed using the resulting finely pulverized material. Otherwise, the magnetic composite was fabricated in the same manner as in Example 1.

[0082] [Example 11 (Comparative Example)] In Example 11, the ferrite layer was formed using the calcined material (calcined granules) without any pulverization treatment. Otherwise, the magnetic composite was fabricated in the same manner as in Example 1.

[0083] [Example 12 (Comparative Example)] In Example 12, a planetary ball mill was used instead of a dry bead mill during the grinding process of the calcined material (calcined granules). Otherwise, the magnetic composite was fabricated in the same manner as in Example 1.

[0084] [Example 13 (Comparative Example)] In Example 13, the number of coatings during film formation was changed from 10 to 1. Otherwise, the magnetic composite was fabricated in the same manner as in Example 1.

[0085] [Example 14 (Comparative Example)] In Example 14, the gas flow rate during film deposition was changed from 10.0 L / min to 2.0 L / min. Otherwise, the magnetic composite was fabricated in the same manner as in Example 1.

[0086] The properties of the ferrite powder and substrate used in Examples 1 to 14 are summarized in Table 1 below.

[0087] [Table 1]

[0088] (2) Evaluation For Examples 1-14, the various characteristics were evaluated as follows.

[0089] <Particle size distribution> The particle size distribution of the ferrite powder used for ferrite layer deposition was measured as follows. First, 0.1 g of the sample and 20 ml of water were placed in a 30 ml beaker, and 2 drops of sodium hexametaphosphate were added as a dispersant. Next, the mixture was dispersed using an ultrasonic homogenizer (SMT Corporation, UH-150 model). The output level of the ultrasonic homogenizer was set to 4, and dispersion was performed for 20 seconds. After that, the bubbles formed on the surface of the beaker were removed, and the mixture was introduced into a laser diffraction particle size distribution analyzer (Shimadzu Corporation, SALD-7500nano) for measurement. From this measurement, the 10% cumulative diameter (D10), 50% cumulative diameter (D50; average particle size), and 90% cumulative diameter (D90) in the volume particle size distribution were determined. The measurement conditions were a pump speed of 7, an internal ultrasonic irradiation time of 30, and a refractive index of 1.70-050i.

[0090] <Thickness (ferrite layer)> The thickness of the ferrite layer in the magnetic composite was determined by observing its cross-section using a field emission scanning electron microscope (FE-SEM). Specifically, observation was performed under conditions of an acceleration voltage of 1.0 kV and a magnification of 1000x to obtain cross-sectional SEM images. Then, the thickness of the ferrite layer was determined at 10 arbitrary points in the obtained SEM images, and the average value was calculated.

[0091] <xrd> The substrate and ferrite powder used for ferrite layer deposition, as well as the deposited ferrite layer, were analyzed by X-ray diffraction (XRD). The analytical conditions were as follows.

[0092] - X-ray diffractometer: X'pertMPD manufactured by Panalytical Corporation - Source: Co-Kα - Tube voltage: 45kV -Tube current: 40mA - Scan speed: 0.002° / sec (continuous scan) - Scan range (2θ): 15~90°

[0093] <Small incidence angle XRD> The ferrite layer after film deposition was analyzed by micro-angle incident X-ray diffraction. The analysis conditions were as follows.

[0094] - X-ray diffractometer: Empyrean, manufactured by Panalytical Corporation - Radiation source: Cu LFF Line focus - Sample stage: chi-phi-z stage - Tube voltage: 45kV -Tube current: 40mA - Scan speed: 0.03° / sec (continuous scan) - Scan range (2θ): 15~90°

[0095] <Surface roughness (ferrite layer)> The arithmetic mean height (Ra) and maximum height (Rz) of the ferrite layer surface were evaluated using a laser microscope (Lasertec Corporation, OPTELICS HYBRID). Ten measurements were taken for each sample, and the average value was calculated. The measurements were performed in accordance with JIS B 0601-2001.

[0096] <Surface resistance (ferrite layer)> The surface resistance of the ferrite layer was measured using a resistivity meter (Mitsubishi Chemical Corporation, Hiresta IP MCP-HT260) when 100V was applied. Ten measurements were taken for each sample, and the average value was calculated.

[0097] <Membrane hardness (magnetic composite)> The adhesion between the ferrite layer and the substrate was evaluated using a pencil hardness test (pencil scratch test). The measurement was performed in accordance with the old JIS K5400 standard. In each test, the pencil was scratched five times with a pencil of the same hardness symbol. The tip of the pencil lead was sharpened after each scratch. Note that pencil hardness increases in the following order: 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, 6H, 7H, 8H, 9H, and 10H.

[0098] <Flexibility (magnetic composite)> The flexibility was evaluated by bending tests using cylindrical mandrels. Specifically, mandrels with diameters of 2, 3, 4, 5, 6, 8, 10, 12, 16, 20, 25, and 32 mm were prepared, and the magnetic composite was set with the ferrite layer facing outwards, and then bent 180°. The bending of the test apparatus was performed evenly over a period of 1 to 2 seconds. The above procedure was repeated by changing the diameter of the mandrel to a smaller one, and the diameter of the mandrel at which cracking of the coating or peeling of the coating from the substrate first occurred was recorded. This measurement was performed in accordance with JIS K5600.

[0099] <Magnetic properties (magnetic composites)> The magnetic properties of the magnetic composite were evaluated by adsorption tests using a magnet. Specifically, a neodymium magnet with a surface magnetic flux density of 0.20T and an adsorption force of 14.70N, measuring 10mm square (2mm thick), was prepared. When a 25mm square piece of the magnetic composite was brought within 10mm of the magnet, it was checked whether or not it was attracted to the magnet. The above procedure was repeated five times, changing the sampling location of the magnetic composite. Samples that were attracted every time were judged as "good," and samples that were not attracted even once were judged as "poor."

[0100] (3) Evaluation results The evaluation results obtained for Examples 1-14 are summarized in Table 2 below. In Table 2, surface resistance is expressed in E notation. That is, the number before "E" represents the mantissa, and the number after "E" represents the exponent.

[0101] The sample in Example 9, a resin sheet obtained by kneading ferrite powder and resin (PVA), had an excessively large peak width at half maximum (A / B) ratio in the micro-angle incident XRD profile. As a result, its pencil hardness was low, less than 3B. In addition, its minimum mandrel diameter was large at 20 mm, resulting in poor flexibility.

[0102] In Example 10, where a ferrite layer was deposited using the AD method, the ferrite powder used for deposition had a small particle size of 0.9 μm, resulting in an excessively large peak width at half maximum (A / B) in the micro-angle incident XRD profile. Consequently, the pencil hardness was low (less than 3B), and the minimum mandrel diameter was large (>32 mm). On the other hand, in Examples 11 and 12, where the ferrite powder particle size was large (13.5 μm or 83.5 μm), no ferrite layer deposition was observed, and the substrate surface appeared to have been etched away.

[0103] Furthermore, in Example 13, where a ferrite layer was deposited using the AD method, the ferrite layer thickness was small at 0.24 μm, resulting in an excessively large peak width-to-full ratio (A / B) in the micro-angle incidence XRD profile. Consequently, the pencil hardness was relatively low at H. Similarly, in Example 14, where the gas flow rate during deposition was low, the ferrite layer thickness was small at 0.11 μm, and the peak width-to-full ratio (A / B) was excessively large. Consequently, the pencil hardness was low.

[0104] In contrast, the samples in Examples 1 to 8 had a peak width at half maximum (A / B) ratio in the micro-angle incidence XRD profile that was controlled within an appropriate range. As a result, the pencil hardness was very high, ranging from 6H to 8H, and the adhesion was excellent. Furthermore, the minimum mandrel diameter was relatively small, ranging from 2 to 10 mm, and the flexibility was excellent. Of these, the samples in Examples 1, 2, 5, and 7 had particularly small minimum mandrel diameters of 2 to 4 mm and exhibited excellent flexibility.

[0105] [Table 2]

[0106] Figure 7 shows the X-ray diffraction profile (Co source) of the ferrite layer (magnetic composite) obtained for Example 7, along with the X-ray diffraction profiles of the substrate (copper foil) and ferrite powder (raw material powder) used for ferrite layer deposition. Diffraction peaks based on magnetoplumbite-type hexagonal ferrite were clearly observed in the profiles of the ferrite powder and the ferrite layer.

[0107] From the above results, it is understood that this embodiment provides a magnetic composite with excellent flexibility and adhesion while utilizing the magnetic properties based on magnetoplumbite-type hexagonal ferrite. [Explanation of Symbols]

[0108] 2. Aerosolization Chamber 4. Film deposition chamber 6. Conveying gas source 8. Vacuum Exhaust System 10 Vibrator 12 Raw material container 14 nozzles 16 stages 20 Aerosol Deposition Film Forming Apparatus< / xrd>

Claims

1. A magnetic composite comprising a substrate and a ferrite layer provided on the surface of the substrate, The ferrite layer mainly consists of magnetoplumbite-type hexagonal ferrite, has a thickness of 2.0 μm or more, and in a small-angle incident X-ray diffraction profile using Cu-Kα as a source, the ratio (A / B) of the full width at half maximum A of the (107) diffraction peak of the ferrite layer at an incident angle of 1° to the full width at half maximum B of the (107) diffraction peak of the ferrite layer at an incident angle of 5° is 0.70 or more and 0.95 or less, in a magnetic composite.

2. The magnetic composite according to claim 1, wherein the ferrite layer comprises at least one or both of strontium (Sr) and barium (Ba), iron (Fe), and oxygen (O).

3. The thickness of the substrate (d Ｓ The magnetic composite according to claim 1, wherein the diameter of the ) is 10.0 μm or more.

4. The magnetic composite according to claim 1, wherein the arithmetic mean roughness (Ra) of the surface of the ferrite layer is 0.10 μm or more and 0.30 μm or less.

5. The surface resistance of the ferrite layer is 1.0 × 10⁻⁶ ５ The magnetic composite according to claim 1, wherein the ohm is greater than or equal to Ω.

6. An element or component comprising the magnetic composite according to any one of claims 1 to 5.

7. The element or component according to claim 6, which is at least one selected from the group consisting of an electromagnetic noise absorber, an antenna, a sensor, an actuator, and a motor.

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