Magnetic structure and method for producing same

Abstract

A magnetic structure (10) comprises a non-magnetic substrate (12) and a plurality of columnar magnetic thin films (11). The magnetic thin films are formed from a rare earth magnetic material, and are provided on the non-magnetic substrate. With regard to the in-plane direction of the non-magnetic substrate, there are provided a film forming region (A1) where the magnetic thin films are provided, and a non-film forming region (A2) where no magnetic thin films are provided. A method for producing the magnetic structure comprises the following processes. A raw material powder is produced by mixing: a rare earth magnetic powder forming a main phase; and a grain boundary powder made from a low-melting-point metal material forming a grain boundary material. The non-magnetic substrate is supported with a substrate support section (221) functioning as an orienting magnet. A mask (230) that has an opening (231) of a shape corresponding to the film forming region is overlaid onto a thin film forming surface (13) on the non-magnetic substrate. The magnetic thin films are formed on the thin film forming surface by injecting the raw material powder toward the thin film forming surface where the mask has been overlaid.

Description

[Technical field]

[0001] The present disclosure relates to magnetic structures and methods for making the same. [Background technology]

[0002] For example, in electric devices using permanent magnets, such as motors and generators, miniaturization and high output are universal needs regardless of field or era. Specifically, for example, in order to realize small drones, there is a demand for miniaturization of drive motors. Such drive motors require large torque. For this reason, there is a demand for strengthening the magnetic force of the permanent magnets provided in the small drive motors.

[0003] Alternatively, for example, in the pharmaceutical and drug discovery fields, the development of high-speed, high-efficiency, and high-precision separation technologies for antibodies and proteins is progressing. In protein separation, magnetic particles that can be magnetically recovered are reacted with and adsorbed to proteins, and then recovered using permanent magnets, etc., to recover and extract the target substance. In order to improve the precision and sensitivity of separation technology, efforts are being made to increase the specific reaction area and increase the number of binding targets by micronizing magnetic particles. On the other hand, since the magnetization per particle is determined by the volume, the interaction with the external magnetic field per particle becomes smaller as the magnetic particles become finer. Therefore, with permanent magnet-type collectors, it is difficult to collect only the magnetic nanoparticles that are bound to the target substance because the magnetic field gradient in the collection area is small. For this reason, efforts are being made to use fine SUS filters magnetized by an external magnetic field. In addition, a magnetic recovery device using a superconducting magnet has been proposed to create a strong magnetic field gradient. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-42349 A Summary of the Invention

[0005] As a result of the inventor's earnest study, the following problem was found. Specifically, for example, in order to reduce the size and increase the output of the drive motor, it is preferable to use a permanent magnet made of rare earth elements such as neodymium and samarium. In addition, for example, in magnetic particle recovery devices, devices using permanent magnets are often inexpensive and small, and can be used easily, but the magnetic field gradient is small, and it is difficult to efficiently separate trace substances in a short time. In this regard, a method of inducing a strong magnetic field gradient by using a superconducting magnet to manipulate the electric field over time to increase the magnetic field gradient can be mentioned. However, this method requires a superconducting magnet and a cooling device for it, so the device becomes larger and more expensive. Therefore, in order to induce a strong magnetic field gradient using a permanent magnet, a method of miniaturizing the magnet and imparting a magnetic field gradient can be considered. In this case, it is preferable to use a permanent magnet made of rare earth elements such as neodymium and samarium.

[0006] However, rare earth magnets containing rare earth elements such as neodymium and samarium have excellent magnetic properties, but their oxidation resistance is very low, and even slight oxidation will cause a significant decrease in magnetic properties. In particular, when the size is reduced to a size of less than a micron, the specific surface area becomes large, so that the magnet is immediately oxidized and its performance is significantly reduced. For this reason, there is a limit to how much the material can be reduced in size. In other words, in the conventional technology, it is theoretically impossible to produce magnets with a size less than the particle diameter of the material, and there is a limit to how much the magnet can be reduced in size. In addition, a method of forming a film by controlling the desired composition ratio using vacuum deposition or sputtering using single raw materials is also conceivable. However, the film formation speed is slow, and it is not possible to obtain a practical lamination efficiency per unit time. Furthermore, in the thin film formation process such as sputtering and deposition, a complex post-annealing process is required.

[0007] The present disclosure has been made in consideration of the various circumstances at the time of filing of the present application, as exemplified above, etc. That is, the present disclosure provides a small magnetic structure capable of inducing a strong magnetic field gradient, which is constituted by a magnetic thin film that is a micro-sized permanent magnet made of a rare earth magnetic material that is easily oxidized, for example.

[0008] According to one aspect of the disclosure, the magnetic structure (10) comprises: A non-magnetic substrate (12); A plurality of columnar magnetic thin films (11) formed of a rare earth magnetic material and provided on the non-magnetic substrate; Equipped with A film-formation region (A1) where the magnetic thin film is provided and a non-film-formation region (A2) where the magnetic thin film is not provided are defined in an in-plane direction intersecting with the thickness direction of the non-magnetic substrate. Has The magnetic thin film is made of the rare earth magnetic material and is formed to a thickness thinner than the grain size of the rare earth magnetic powder constituting the raw powder. According to another aspect of the present disclosure, a method for manufacturing the magnetic structure includes the following steps, procedures, or steps: A raw material powder is produced by mixing rare earth magnetic powder constituting a main phase and a grain boundary material powder made of a low melting point metal material constituting a grain boundary material; The non-magnetic substrate is supported by a substrate support portion (221) functioning as an orientation magnet, and a mask (230) having an opening portion (231) having a shape corresponding to the film formation region is superimposed on a thin film formation surface (13) which is the surface of the non-magnetic substrate opposite a back surface (14) facing the substrate support portion; The raw material powder is sprayed toward the thin film formation surface on which the mask is superimposed, thereby forming the magnetic thin film on the thin film formation surface.

[0009] In addition, in each section of the application documents, each element may be given a reference number in parentheses. In this case, the reference number merely indicates an example of the correspondence between the element and a specific configuration described in the embodiment described later. Therefore, the present disclosure is not limited in any way by the description of the reference number. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is an enlarged perspective view showing a schematic configuration of a magnetic structure according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram showing a schematic configuration of a magnetic structure manufacturing apparatus used for manufacturing the magnetic structure shown in FIG. [Diagram 3] FIG. 3 is an enlarged front view of the mask shown in FIG. 2. [Figure 4] FIG. 2 is a flow chart showing an outline of a manufacturing process for the magnetic structure shown in FIG. [Diagram 5] 2 is a table showing deposition conditions and results in one example of deposition of the magnetic thin film shown in FIG. 1. [Figure 6] 6 is a graph showing a result of film formation according to the film formation example shown in FIG. 5. [Figure 7] 2 is a table showing deposition conditions and results in another example of deposition of the magnetic thin film shown in FIG. 1. [Figure 8] 8 is a graph showing a result of film formation according to the film formation example shown in FIG. 7. [Figure 9] 2 is a table showing deposition conditions and results in yet another example of deposition of the magnetic thin film shown in FIG. [Figure 10] 10 is a graph showing a result of film formation according to the film formation example shown in FIG. [Figure 11] 2 is a table showing deposition conditions and results in yet another example of deposition of the magnetic thin film shown in FIG. [Figure 12] 12 is a graph showing a result of film formation according to the film formation example shown in FIG. 11. [Figure 13] 2 is a scanning electron microscope photograph showing the appearance of the magnetic structure shown in FIG. 1. [Figure 14] 3 is a graph showing the particle size distribution of raw material powder used in the magnetic structure manufacturing apparatus shown in FIG. 2. [Figure 15] 2 is a graph showing the grain size distribution of the magnetic thin film according to the example of film formation that does not include the grain boundary material of the magnetic thin film shown in FIG. 1. [Figure 16] 2 is a graph showing a grain size distribution of the magnetic thin film according to the example of film formation including the grain boundary material of the magnetic thin film shown in FIG. 1. [Figure 17] 17 is a table summarizing the particle size distributions shown in FIGS. 14 to 16. [Figure 18] 3 is an enlarged front view showing another configuration example of the mask shown in FIG. 2. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present disclosure will be described based on the drawings. Note that, if various modified examples applicable to one embodiment are inserted in the middle of a series of explanations regarding the embodiment, understanding of the embodiment may be hindered. For this reason, the modified examples are not inserted in the middle of a series of explanations regarding the embodiment, but are explained together thereafter. In addition, the description of each drawing and the description of the device configuration and its functions and operations described below corresponding thereto are simplified to briefly explain the contents of the present disclosure, and do not limit the contents of the present disclosure in any way. For this reason, it goes without saying that each drawing does not necessarily match a diagram showing a specific configuration that is actually manufactured and sold. In other words, it goes without saying that the present disclosure should not be interpreted as being limited by the description of each drawing and the description of the device configuration and its functions and operations described below corresponding thereto, unless the applicant explicitly limits it by the prosecution history of the present application, etc.

[0012] (Schematic configuration of the magnetic structure) Referring to FIG. 1, the magnetic structure 10 includes a magnetic thin film 11 and a non-magnetic substrate 12. The non-magnetic substrate 12 has a pair of main surfaces, a thin film forming surface 13 and a back surface 14. The "main surface" is a surface of a plate-like or film-like object that is perpendicular to the thickness direction. Specifically, the magnetic structure 10 has a configuration in which the magnetic thin film 11 is provided on the thin film forming surface 13, which is one main surface of a thin plate-like or thin film-like non-magnetic substrate 12. In addition, in one configuration example of the magnetic structure 10 shown in this embodiment, the non-magnetic substrate 12 is formed in a flat plate shape. Hereinafter, a direction that intersects (i.e., typically perpendicular to) the thickness direction of the non-magnetic substrate 12 and that is along the thin film forming surface 13 is referred to as an "in-plane direction".

[0013] The magnetic thin film 11 is made of a rare earth magnetic material. Preferably, the magnetic thin film 11 is made of a rare earth magnetic material forming a main phase and a grain boundary material made of a low melting point metal material. Specifically, for example, the magnetic thin film 11 is configured to contain a samarium-iron-nitrogen magnetic material as a main phase and 15 weight percent or less of zinc as a grain boundary material. The non-magnetic substrate 12, which is the base material, is made of metal, ceramics, synthetic resin, or the like.

[0014] In this embodiment, the magnetic structure 10 has a film-forming region A1 in which the magnetic thin film 11 is provided in the in-plane direction, and a non-film-forming region A2 in which the magnetic thin film 11 is not provided in the in-plane direction. The film-forming region A1 and the non-film-forming region A2 are arranged so as to be adjacent to each other in the in-plane direction. In one configuration example of the magnetic structure 10 shown in this embodiment, a plurality of magnetic thin films 11 formed in a columnar shape (for example, a cylindrical shape) protruding along the thickness direction of the non-magnetic substrate 12 are provided along the in-plane direction. Specifically, the magnetic thin films 11 are provided at approximately constant intervals in a first direction (i.e., the left-right direction in the figure) and a second direction that are in-plane directions and intersect with each other. That is, the plurality of magnetic thin films 11 are arranged at predetermined intervals (for example, intervals of 450 μm or less) in the first direction and the second direction. In addition, the magnetic thin films 11 are formed so that D / L=0.7 to 350, where D is the outer diameter and L is the film thickness. In this way, the film-forming region A1 is formed by a plurality of magnetic thin films 11 arranged along the in-plane direction. On the other hand, the non-film-forming region A2 is formed by a portion of the thin film formation surface 13 where no magnetic thin film 11 is provided. Furthermore, the magnetic thin films 11 are formed so that Sa / (Sa+Sb)≧0.17, where Sa is the area of ​​the film-forming region A1 and Sb is the area of ​​the non-film-forming region A2.

[0015] The magnetic thin film 11 is made of a rare earth magnetic material and is formed to a thickness thinner than the grain size of the rare earth magnetic powder constituting the raw material powder. That is, the submicron-sized magnetic thin film 11 is formed by spraying micron-sized raw material powder containing rare earth magnetic powder onto the non-magnetic substrate 12 using a magnetic structure manufacturing apparatus 20 described below. Specifically, the magnetic thin film 11 is formed to have an outer diameter (for example, diameter in the case of a cylindrical shape) of 350 μm or less and a thickness (i.e., height) of 100 nm or more.

[0016] (Magnetic structure manufacturing equipment) Fig. 2 shows a schematic configuration of a magnetic structure manufacturing apparatus 20 used for manufacturing the magnetic structure 10 shown in Fig. 1. The magnetic structure manufacturing apparatus 20 is configured to form a magnetic thin film 11 on the non-magnetic substrate 12 by a cold spray method in which raw material powder is sprayed onto the non-magnetic substrate 12. Specifically, as shown in Fig. 2, the magnetic structure manufacturing apparatus 20 includes a raw material powder generating section 21 and a molding section 22.

[0017] The raw powder generating unit 21 is configured to generate raw powder by mixing rare earth magnetic powder forming the main phase and grain boundary material powder made of a low melting point metal material forming the grain boundary material, and to supply the generated raw powder to the molding unit 22. Specifically, the raw powder generating unit 21 includes a raw material supply unit 211, a nanoparticle synthesis device 212, and a mixer 213. The raw material supply unit 211 is provided to supply the rare earth magnetic powder and the grain boundary material powder to the nanoparticle synthesis device 212 and the mixer 213. The nanoparticle synthesis device 212 is configured to synthesize grain boundary material powder made of nanoparticles by a thermal plasma method similar to that of JP 2021-59754 A, which is a prior application of the applicant of the present application. The mixer 213 is provided to generate raw material powder and granulate to a predetermined particle size by mixing and stirring the grain boundary material powder and rare earth magnetic powder synthesized by the nanoparticle synthesis device 212.

[0018] The molding unit 22 is configured to inject the raw material powder supplied from the raw material powder generation unit 21 toward the non-magnetic substrate 12 by a high-velocity gas stream in an inert gas atmosphere. Specifically, as shown in FIG. 2, the molding unit 22 includes a substrate support unit 221, a spray gun 222, a powder supplying device 223, and a working gas supplying unit 224.

[0019] The substrate support part 221 is disposed at the destination of the raw material powder sprayed by the spray gun 222. The substrate support part 221 is provided to support the non-magnetic substrate 12 with the thin film forming surface 13 facing the spray gun 222 by being joined to the back surface 14 of the non-magnetic substrate 12. The substrate support part 221 is formed in a plate shape having a thickness direction along the spray direction of the raw material powder. In this embodiment, the substrate support part 221 is formed of a permanent magnet such as a heat-resistant neodymium magnet so as to function as an orientation magnet for the formed magnetic thin film 11. The spray gun 222 is provided to spray the raw material powder supplied from the powder supply device 223 toward the non-magnetic substrate 12 supported by the substrate support part 221 by a high-speed gas flow of the working gas supplied from the working gas supply part 224. The molding section 22 is configured to be able to move the spraying position on the thin film formation surface 13 two-dimensionally in an in-plane direction by relatively moving the substrate support section 221 and the spray gun 222 in an in-plane direction that intersects (e.g., perpendicular to) the spraying direction of the raw material powder.

[0020] The powder supplying device 223 is provided to supply the raw material powder supplied from the raw material powder generating unit 21 to the spray gun 222. The working gas supplying unit 224 is provided to supply the working gas to the spray gun 222 from a gas cylinder (not shown) in which high-pressure gas is sealed. The working gas supplying unit 224 also includes a gas heater 225. The gas heater 225 is provided to be able to heat the working gas supplied to the spray gun 222 as necessary.

[0021] (Manufacturing method) Hereinafter, there will be described a method for manufacturing the magnetic structure 10 by the magnetic structure manufacturing apparatus 20 shown in Fig. 2. This manufacturing method includes a raw material powder producing step, a film formation preparation step, and a film formation step.

[0022] The raw powder generating step is a step of generating raw powder by mixing rare earth magnetic powder forming the main phase and grain boundary material powder made of a low melting point metal material forming the grain boundary material. Specifically, in this embodiment, grain boundary material powder is synthesized from a low melting point metal material, and the synthesized grain boundary material powder and rare earth magnetic powder are mixed and granulated to generate raw powder. Preferably, the raw powder contains magnetic powder made of a rare earth magnetic material and grain boundary material powder made of a low melting point metal material. Specifically, the raw powder contains zinc powder as grain boundary material powder in an amount of 15 weight percent or less. The zinc powder is made of zinc nanoparticles having a particle size of 1 μm or less, preferably 100 nm or less, more preferably 20 nm or less, and even more preferably 5 nm or less. The raw powder generating step is performed in the raw powder generating unit 21. In this embodiment, granulation is performed using a stirring granulation method that utilizes centrifugal force. In the stirring granulation method, the particle size of the raw powder can be adjusted by the rotation speed and rotation time of the stirring blade. Furthermore, if necessary, the raw material powder producing section 21 may carry out a classification step of separating and extracting raw material powder having a particle size within a certain range.

[0023] The film formation preparation step is a step of forming a state in which the non-magnetic substrate 12 with the mask 230 superimposed on the thin film formation surface 13 is supported by the substrate support part 221. As shown in FIG. 3, the mask 230 has an opening 231 having a shape corresponding to the film formation region A1. That is, the opening 231 is a substantially circular through hole corresponding to the outer shape of the magnetic thin film 11, and has a hole diameter DD corresponding to the outer diameter of the magnetic thin film 11. The pitch P between adjacent openings 231 is set to 450 μm or less. The non-magnetic substrate 12 is supported by the substrate support part 221 by facing the back surface 14 to the substrate support part 221, and a part of the thin film formation surface 13 is covered by the mask 230. The part of the thin film formation surface 13 exposed to the outside through the opening 231 faces the spray gun 222, making it possible to form the magnetic thin film 11.

[0024] The film forming process is a process of forming a magnetic thin film 11 on a non-magnetic substrate 12 with a mask 230 superimposed thereon by spraying raw material powder toward the thin film forming surface 13 exposed to the outside through an opening 231. That is, the working gas supplied to the spray gun 222 is sprayed from the spray gun 222 as a supersonic high-speed gas flow. At this time, the raw material powder sprayed onto the thin film forming surface 13 by the high-speed gas flow of the working gas collides with and adheres to the thin film forming surface 13, forming a film as the magnetic thin film 11. By moving the substrate support part 221 and the spray gun 222 relative to each other in the in-plane direction and moving the spraying position on the thin film forming surface 13 two-dimensionally in the in-plane direction, the raw material powder can be sprayed uniformly over the entire surface of the thin film forming surface 13. Then, assuming that one spray of raw material powder over the entire surface of the thin film forming surface 13 is one pass, the magnetic thin film 11 can be formed with any thickness, i.e., height, by adjusting the number of passes, which is the number of times that one pass is repeated. Furthermore, the non-magnetic substrate 12 on which the magnetic thin film 11 is formed is supported by a substrate support 221 that functions as an orientation magnet. Therefore, the magnetic thin film 11 can be oriented, for example, in the direction perpendicular to the surface, which is the direction along the thickness direction. Here, in this embodiment, the film formation process is preferably performed in an inert gas atmosphere with an oxygen concentration of 1000 ppm or less.

[0025] In this embodiment, the pressure of the high-velocity gas stream in the working gas is preferably set to 0.5 MPa or more. Furthermore, the working gas supplied to the spray gun 222 by the working gas supply unit 224 is heated by the gas heater 225 as necessary. In this embodiment, the gas temperature in the high-velocity gas stream is preferably set to 100° C. or less.

[0026] Since the working gas has a temperature lower than the melting point of the material constituting the raw powder, the raw powder particles collide with the thin film formation surface 13 exposed at the opening 231 in the mask 230 while remaining in a solid phase. The raw powder particles collide with and adhere to the thin film formation surface 13, forming a magnetic thin film 11 on the thin film formation surface 13. After the film is formed, the mask 230 is peeled off to obtain the magnetic structure 10 having the configuration shown in FIG. 1. The manufacturing method as described above is summarized in FIG. 4. Here, "material synthesis" corresponds to the preparation of raw powder by the nanoparticle synthesis device 212 in the raw powder production unit 21. "Mixing" corresponds to the granulation process by the mixer 213 in the raw powder production unit 21. "Material synthesis" and "mixing" are included in the raw powder production process. "Mask processing" is a process of preparing, i.e., forming, the mask 230 having the configuration shown in FIG. 3, and is included in the film formation preparation process. "Film formation" includes the film formation process and the part of the film formation preparation process other than the preparation of the mask 230.

[0027] (effect) In the magnetic structure 10 having the above configuration, the magnetic thin films 11 constituting the rare earth permanent magnet are arranged at minute intervals, thereby realizing a locally high gradient magnetic field distribution. This makes it possible to provide a small magnetic structure 10 that can induce a strong magnetic field gradient and is composed of the magnetic thin films 11 that are micro-sized permanent magnets made of a rare earth magnetic material that is easily oxidized. Specifically, for example, when the magnetic structure 10 is used in an electric device such as a rotating electric machine, it is possible to obtain high output required for a driving motor of a small drone or the like while successfully miniaturizing the electric device. Alternatively, for example, when the magnetic structure 10 is used as a magnetic filter for collecting magnetic nanoparticles, it becomes possible to collect the magnetic nanoparticles with high efficiency and high accuracy using a simple and small device. In other words, it becomes possible to realize a simple and small magnetic collection device without applying a magnetic field from the outside using a large magnet or a superconducting magnet.

[0028] Here, the smaller the outer diameter of the magnetic thin film 11, the higher the magnetic gradient. Also, the greater the height, i.e., the film thickness, of the magnetic thin film 11, the greater the magnetization that can be obtained. As a result, it is possible to improve the performance (e.g., output and recovery efficiency) of a device using the magnetic structure 10. Also, by narrowing the gap between adjacent magnetic thin films 11 as much as possible, it is possible to improve the performance of a device using the magnetic structure 10. Therefore, the magnetic thin film 11 can be preferably formed to have a diameter of 350 μm or less and a height of 100 nm or more. Also, the gap between adjacent magnetic thin films 11 can be preferably set to 450 μm or less.

[0029] In the above manufacturing method, the cold spray method is used to form the magnetic thin film 11, and the strong impact force during film formation refines the crystals to a particle size equivalent to the diameter of a single magnetic domain particle. This makes it possible to provide a magnetic structure 10 having a high-density magnetic thin film 11 with a film thickness equal to or smaller than the particle size of the raw material powder. That is, the above manufacturing method makes it possible to form a submicron-sized film from micron-sized raw material particles. Specifically, even if raw material powder prepared using samarium-iron-nitrogen magnetic powder with a particle size of 3 μm or more and 20 μm or less is used, the particle size of the samarium-iron-nitrogen after film formation is at the submicron level. This maximizes the magnetic properties. Note that if the particle size of the rare earth magnetic powder, such as samarium-iron-nitrogen magnetic material powder contained in the raw material powder, is too small, the collision energy during film formation is small and the pulverization effect cannot be obtained. On the other hand, if the particle size is too large, the magnetic properties are reduced.

[0030] There is a concern that the oxidation resistance of the rare earth magnet material particles constituting the magnetic thin film 11 may decrease if they are made fine. For this reason, in this embodiment, a grain boundary material is added to coat the surface of the rare earth magnet particles with the grain boundary material during film formation, thereby improving the oxidation resistance. In addition, this grain boundary material also plays a role as a binder for improving adhesion to the non-magnetic substrate 12. That is, by adjusting the grain size, composition, mixing ratio, and mixing method of the grain boundary material, good oxidation resistance due to the coating of the surface of the rare earth magnet particles and good adhesion to the non-magnetic substrate 12, which is the base material, can be realized. The smaller the grain size of the grain boundary material, the lower the melting point, so film formation at a low temperature is possible and the magnetic properties are improved. In addition, the lower the mixing ratio of the grain boundary material, the higher the saturation magnetization, and the higher the mixing ratio, the better the adhesion. Here, by using zinc nanoparticles as the grain boundary material powder, the magnetic performance is improved. By reducing the particle size of the zinc nanoparticles, the magnetic thin film 11 becomes denser. For this reason, it is preferable to contain 15 weight percent or less of zinc powder consisting of zinc nanoparticles with a particle size of 1 μm or less, preferably 100 nm or less, more preferably 20 nm or less, and even more preferably 5 nm or less. Note that commercially available zinc particles have a large particle size, are difficult to densify, and have a high melting point. Furthermore, it is preferable to carry out the raw powder production process in an inert gas atmosphere.

[0031] In this embodiment, the film formation process is performed in an inert gas atmosphere with an oxygen concentration of 1000 ppm or less. By lowering the oxygen concentration, decomposition of the rare earth magnetic material is suppressed. Specifically, for example, when the rare earth magnetic material is a samarium-iron-nitrogen based magnetic material, precipitation of soft magnetic α-Fe due to decomposition is suppressed. This improves the magnetic properties.

[0032] The higher the pressure of the high-velocity gas flow in the working gas, the finer and denser the crystals after film formation will be, and the better the magnetic properties will be. For this reason, the pressure of the high-velocity gas flow in the working gas is preferably 0.5 MPa or higher.

[0033] The film formation efficiency improves when the temperature of the working gas is as high as possible within the temperature range below the melting point or softening point of the raw material powder particles. On the other hand, by keeping the temperature of the working gas as low as possible, the grains constituting the magnetic thin film 11 are prevented from becoming large, and decomposition of the rare earth magnetic material is also prevented. For this reason, in this embodiment, the gas temperature in the high-velocity gas stream can be preferably set to 100° C. or less.

[0034] In this way, the above-mentioned manufacturing method makes it possible to inexpensively manufacture a small magnetic structure 10 that is capable of inducing a strong magnetic field gradient and is made of a magnetic thin film 11 that is a micro-sized permanent magnet made of an easily oxidized rare earth magnetic material. Also, it becomes possible to form the magnetic thin film 11 in any shape and arrangement.

[0035] (Example) Below, we will introduce a representative example of the formation of the magnetic thin film 11. First, the synthesis conditions for zinc nanoparticles used as the raw material powder are as follows. Plasma power: 6kW Gas type: Ar+3%H 2 Gas flow rate: 40L / min Chamber pressure: 90kPa Carrier gas type: Ar Carrier gas flow rate: 3L / min Oxygen concentration in furnace: less than 0.1 ppm

[0036] In addition, in a specific example of film formation shown here, a synthetic resin film with a thickness of 15 μm was used as the mask 230, and a plurality of openings 231 were provided with a hole diameter DD of 350 μm and a pitch P of 450 μm. Note that this example of film formation is intended to specifically show one embodiment of the magnetic structure 10 according to the present disclosure and the manufacturing method thereof, and does not limit the contents of the present disclosure. That is, as will be described later, the present disclosure is not limited to such an embodiment, and there is no particular limitation on the material and thickness of the mask 230, the shape and arrangement of the openings 231, and the like.

[0037] Figures 5 and 6 show the change in film thickness of magnetic thin film 11 with the change in the number of passes. The film thickness was determined using a micrometer by subtracting the film thickness of non-magnetic substrate 12 before film formation from the total film thickness including non-magnetic substrate 12 after film formation. In Figure 6, the vertical axis indicates film thickness and the horizontal axis indicates the number of passes. As shown in Figures 5 and 6, it was confirmed that the film thickness increased with the number of passes.

[0038] 7 and 8 show the change in the film thickness of the magnetic thin film 11 when the presence or absence of zinc powder as the grain boundary material powder, the grain size, and the working gas temperature are changed. In the film formation examples of FIG. 7 and FIG. 8, nitrogen gas was used as the working gas. In FIG. 8, the vertical axis indicates the film thickness, and the horizontal axis indicates the working gas temperature. In addition, in FIG. 8, the circular plots correspond to Examples 2-1 to 2-4, i.e., without the grain boundary material. The triangular plots correspond to Examples 2-5 to 2-8, i.e., the average grain size of the grain boundary material is 5 nm. The square plots correspond to Examples 2-9 to 2-12, i.e., the average grain size of the grain boundary material is 20 nm. The inverted triangular plots correspond to Examples 2-13 to 2-14, i.e., the average grain size of the grain boundary material is 100 nm. The cross plots correspond to Examples 2-15 to 2-16, i.e., the average grain size of the grain boundary material is 1000 nm (i.e., 1 μm). The average grain size was calculated using a cross-sectional photograph taken by a scanning electron microscope. As shown in Figures 7 and 8, the film-forming property improved with an increase in the working gas temperature. Also, the film-forming property improved with the addition of zinc powder as the grain boundary material powder. Furthermore, the film-forming property improved with a smaller grain size of zinc powder as the grain boundary material powder.

[0039] 9 and 10 show the effect of an increase in the working gas temperature on the denseness of the magnetic thin film 11. The density was determined by using a liquid weighing method with an ethanol solvent to first determine the density of the non-magnetic substrate 12 before film formation, and then performing arithmetic processing from the overall density after film formation to determine the density of only the formed magnetic thin film 11. Here, the true density of samarium-iron-nitrogen is 7.63 g / cm 3 and the true density of zinc is 7.13 g / cm 3 Therefore, the maximum theoretical density estimated from the mixture ratio is about 7.6 g / cm 3In FIG. 10, the vertical axis indicates density, and the horizontal axis indicates working gas temperature. In FIG. 10, the black filled triangle plots indicate Examples 3-1 to 3-4, and the open triangle plots indicate density calculation values ​​in the case of no zinc addition corresponding to Examples 3-1 to 3-4. As shown in FIG. 9 and FIG. 10, the addition of zinc grain boundary material improved the denseness of the magnetic thin film 11. Furthermore, the density of the magnetic thin film 11 was almost constant regardless of the working gas temperature, and a packing rate of almost 100% was obtained. When the cross section of the magnetic thin film 11 after the film formation was confirmed using an image taken by a scanning electron microscope, no major defects were found, and it was confirmed that a dense film with a packing rate of 97 vol% or more was formed.

[0040] Figures 11 and 12 show the effect of oxygen concentration on the coercivity of magnetic thin film 11. In Figure 12, the vertical axis represents coercivity, and the horizontal axis represents working gas temperature. In Figure 12, circular plots represent Examples 4-1 to 4-4, i.e., cases where the oxygen concentration was 0.1 ppm, and square plots represent Examples 4-5 to 4-8, i.e., cases where the oxygen concentration was 1000 ppm. As shown in Figures 11 and 12, the lower the oxygen concentration, the higher the coercivity obtained.

[0041] 13 shows a scanning electron microscope photograph of a representative example of film formation using a mask 230 made of a synthetic resin film with a thickness of 15 μm and having a plurality of openings 231 with a hole diameter DD of 350 μm and a pitch P of 450 μm. As shown in FIG. 13, it was confirmed that the magnetic thin film 11 was formed in accordance with the shape and formation pattern of the openings 231 in the mask 230.

[0042] FIG. 14 shows the particle size distribution of the raw material powder. FIG. 15 shows the particle size distribution of the magnetic thin film 11 when no grain boundary material is included as in Examples 2-1 to 2-4. FIG. 16 shows the particle size distribution of the magnetic thin film 11 when a grain boundary material is included. These particle size distributions were calculated using cross-sectional photographs taken with a scanning electron microscope. FIG. 17 is a table summarizing these results. As is clear from the results shown in FIG. 14 to FIG. 17, it was confirmed that the grain size in the magnetic thin film 11 formed by the cold spray method is finer than that of the raw material powder, and that the magnetic thin film 11, which is a thin film magnet with a high density and dense structure, can be obtained.

[0043] (Modification) The present disclosure is not limited to the above embodiment. Therefore, the above embodiment can be modified as appropriate. Representative modified examples will be described below. In the following description of the modified examples, differences from the above embodiment will be mainly described. In addition, the same reference numerals are used for parts that are the same or equivalent to each other in the above embodiment and the modified examples. Therefore, in the following description of the modified examples, the description of the above embodiment can be appropriately used for components having the same reference numerals as the above embodiment, unless there is a technical contradiction or special additional explanation.

[0044] The present disclosure is not limited to the specific configurations shown in the above embodiments. For example, in the magnetic structure 10, the non-magnetic substrate 12 may be in a bent state. That is, for example, the non-magnetic substrate 12 may be formed to be bendable. Specifically, for example, the non-magnetic substrate 12 may be a flexible synthetic resin film.

[0045] The magnetic structure manufacturing apparatus 20 may be a low-pressure type cold spray apparatus with a working gas pressure of 1 MPa or less, or a high-pressure type cold spray apparatus with a working gas pressure of more than 1 MPa. The magnetic structure manufacturing apparatus 20 may also be provided with a temperature adjustment device that adjusts the temperature of the non-magnetic substrate 12 within a certain range. This makes it possible to control the film formation conditions of the magnetic thin film 11 and adjust the grain size, etc.

[0046] The present disclosure is not limited to the specific manufacturing method shown in the above embodiment. That is, for example, the method of forming the magnetic thin film 11 is not limited to the cold spray method. Specifically, for example, the magnetic structure manufacturing apparatus 20 may be configured to form the magnetic thin film 11 on the non-magnetic substrate 12 by the aerosol deposition method. In addition, the material and thickness of the mask 230, the shape and arrangement of the openings 231, etc. may also be appropriately changed. Specifically, for example, the arrangement of the multiple openings 231 may be appropriately changed from the specific example shown in FIG. 3. In addition, as shown in FIG. 18, the openings 231 may be formed in a slit shape extending in the left-right direction in the figure, and may be arranged in a plurality of slits in the up-down direction in the figure. In this case, the film formation region A1 and the non-film formation region A2 are arranged so as to be adjacent to each other in the up-down direction in the figure, which is the in-plane direction. The slit width Ds may be set to, for example, 350 μm or less. In addition, the slit interval Ps may be set to, for example, 450 μm or less. However, the slit width and the slit interval are not limited to these. There is no particular limitation on the shape of the slit end. Furthermore, the slit-shaped opening 231 can be divided into multiple parts in the extension direction (i.e., the left-right direction in FIG. 18). In this way, according to the present disclosure, it is possible to easily form a submicron structure with any patterning.

[0047] In the above description, a plurality of components that were formed seamlessly and integrally with each other may be formed by bonding separate members together. Similarly, a plurality of components that were formed by bonding separate members together may be formed seamlessly and integrally with each other. Furthermore, in the above description, a plurality of components that were formed from the same material may be formed from different materials together. Similarly, a plurality of components that were formed from different materials together may be formed from the same material together.

[0048] Needless to say, the elements constituting the above-mentioned embodiments are not necessarily essential, except when expressly stated as essential or when clearly considered essential in principle. In addition, when the numbers, amounts, ranges, etc. of the components are mentioned, the present disclosure is not limited to the specific values, except when expressly stated as essential or when clearly limited to a specific value in principle. Similarly, when the shapes, directions, positional relationships, etc. of the components are mentioned, the present disclosure is not limited to the shapes, directions, positional relationships, etc., except when expressly stated as essential or when clearly limited to a specific shape, direction, positional relationship, etc. in principle.

[0049] The modified examples are not limited to the above examples. In addition, multiple modified examples may be combined with each other unless technically inconsistent.

[0050] (Disclosure Perspective) As is apparent from the above description, the present disclosure includes at least each of the aspects described below. <Point 1> The magnetic structure (10) comprises: A non-magnetic substrate (12); A plurality of columnar magnetic thin films (11) formed of a rare earth magnetic material and provided on the non-magnetic substrate; Equipped with In an in-plane direction intersecting the thickness direction of the non-magnetic substrate, there are a film-formed region (A1) where the magnetic thin film is provided, and a non-film-formed region (A2) where the magnetic thin film is not provided. <Point 2> In Viewpoint 1, assuming that the area of ​​the film-formed region is Sa and the area of ​​the non-film-formed region is Sb, Sa / (Sa+Sb)≧0.17. <Point 3> In the first and second aspects, the magnetic thin film is made of the rare earth magnetic material and is formed to have a thickness thinner than the grain size of the rare earth magnetic powder constituting the raw powder. <Point 4> In the first to third aspects, a plurality of the magnetic thin films are arranged at predetermined intervals. <Point 5> In a fourth aspect, the predetermined interval is 450 μm or less. <Point 6> In the aspects 1 to 5, when the outer diameter of the magnetic thin film is D and the thickness of the magnetic thin film is L, D / L=0.7~350. <Point 7> In the first to sixth aspects, the magnetic thin film is formed to have an outer diameter of 350 μm or less and a thickness of 100 nm or more. <Point 8> In the first to seventh aspects, the magnetic thin film includes the rare earth magnet material and a grain boundary material made of a low melting point metal material. <Point 9> In aspect 8, the magnetic thin film contains zinc as the grain boundary material in an amount of 15 weight percent or less. <Point 10> In the first to ninth aspects, the rare earth magnetic material is a samarium-iron-nitrogen magnetic material. <Point 11> A method for manufacturing a magnetic structure (10) comprising a non-magnetic substrate (12) and a plurality of columnar magnetic thin films (11) formed of a rare earth magnetic material and provided on the non-magnetic substrate, the magnetic structure having a deposition region (A1) where the magnetic thin films are provided and a non-deposition region (A2) where the magnetic thin films are not provided in an in-plane direction intersecting with a thickness direction of the non-magnetic substrate, includes the following processes, procedures, or steps: A raw material powder is produced by mixing rare earth magnetic powder constituting a main phase and a grain boundary material powder made of a low melting point metal material constituting a grain boundary material; The non-magnetic substrate is supported by a substrate support portion (221) functioning as an orientation magnet, and a mask (230) having an opening portion (231) having a shape corresponding to the film formation region is superimposed on a thin film formation surface (13) which is the surface of the non-magnetic substrate opposite a back surface (14) facing the substrate support portion; The raw material powder is sprayed toward the thin film formation surface on which the mask is superimposed, thereby forming the magnetic thin film on the thin film formation surface. <Point 12> In an eleventh aspect, the magnetic thin film is formed so as to satisfy the following formula, where Sa is the area of ​​the film-formed region and Sb is the area of ​​the non-film-formed region. Sa / (Sa+Sb)≧0.17 <Point 13> In the eleventh and twelfth aspects, the magnetic thin film is formed to a thickness smaller than the grain size of the rare earth magnetic powder. <Point 14> In the eleventh to thirteenth aspects, a plurality of the magnetic thin films are arranged at predetermined intervals. <Point 15> In a fourteenth aspect, the predetermined interval is 450 μm or less. <Point 16> In Aspects 11 to 15, when the outer diameter of the magnetic thin film is D and the thickness of the magnetic thin film is L, the magnetic thin film is formed so as to satisfy the following formula: D / L=0.7~350 <Point 17> In the eleventh to sixteenth aspects, the magnetic thin film is formed to have an outer diameter of 350 μm or less and a thickness of 100 nm or more. <Point 18> In Aspects 11 to 17, the injection of the raw material powder toward the thin film formation surface on which the mask is superimposed is performed by a high-velocity gas stream in an inert gas atmosphere having an oxygen concentration of 1000 ppm or less. <Point 19> In aspect 18, the gas pressure in the high-velocity gas stream is 0.5 MPa or more. <Point of View 20> In aspects 18 and 19, the gas temperature in the high-velocity gas stream is 100° C. or less. <Point 21> In the eleventh to twentyth aspects, the raw material powder includes a magnetic powder made of the rare earth magnet material, and a grain boundary material powder made of a low melting point metal material. <Point of View 22> In a twenty-first aspect, the raw material powder contains zinc powder as the grain boundary material powder in an amount of 15 weight percent or less. <Point of View 23> In a twenty-second aspect, the zinc powder is made of zinc nanoparticles having a particle size of 1 μm or less, preferably 100 nm or less, more preferably 20 nm or less, and even more preferably 5 nm or less. <Point of View 24> In Aspects 11 to 23, the rare earth magnetic material is a samarium-iron-nitrogen magnetic material.

Claims

1. A magnetic structure (10), comprising: A non-magnetic substrate (12); A plurality of columnar magnetic thin films (11) formed of a rare earth magnetic material and provided on the non-magnetic substrate; Equipped with a film-formation region (A1) in which the magnetic thin film is provided and a non-film-formation region (A2) in which the magnetic thin film is not provided in an in-plane direction intersecting a thickness direction of the non-magnetic substrate, The magnetic thin film is made of the rare earth magnetic material and is formed to a thickness thinner than the grain size of the rare earth magnetic powder constituting the raw powder. magnetic structure.

2. If the area of ​​the film-formed region is Sa and the area of ​​the non-film-formed region is Sb, Sa / (Sa + Sb) ≧ 0.17; The magnetic structure of claim 1 .

3. A plurality of the magnetic thin films are arranged at predetermined intervals. The magnetic structure of claim 1 .

4. The predetermined interval is 450 μm or less. The magnetic structure of claim 3.

5. If the outer diameter of the magnetic thin film is D and the thickness of the magnetic thin film is L, then D / L = 0.7 to 350; The magnetic structure of claim 1 .

6. The magnetic thin film is formed to have an outer diameter of 350 μm or less and a thickness of 100 nm or more. The magnetic structure of claim 1 .

7. the magnetic thin film includes the rare earth magnet material and a grain boundary material made of a low melting point metal material; The magnetic structure of claim 1 .

8. The magnetic thin film contains zinc as the grain boundary material in an amount of 15 weight percent or less. The magnetic structure of claim 7.

9. The rare earth magnet material is a samarium-iron-nitrogen based magnet material. The magnetic structure according to any one of claims 1 to 8.

10. A method for manufacturing a magnetic structure (10) comprising a non-magnetic substrate (12) and a plurality of columnar magnetic thin films (11) formed of a rare earth magnetic material and provided on the non-magnetic substrate, the magnetic structure having a film-formed region (A1) in which the magnetic thin films are provided and a non-film-formed region (A2) in which the magnetic thin films are not provided in an in-plane direction intersecting a thickness direction of the non-magnetic substrate, the method comprising the steps of: A raw material powder is produced by mixing rare earth magnetic powder constituting a main phase and a grain boundary material powder made of a low melting point metal material constituting a grain boundary material; The non-magnetic substrate is supported by a substrate support portion (221) functioning as an orientation magnet, and a mask (230) having an opening portion (231) having a shape corresponding to the film formation region is superimposed on a thin film formation surface (13) which is the surface of the non-magnetic substrate opposite to a back surface (14) facing the substrate support portion; the raw material powder is sprayed toward the thin film formation surface on which the mask is superimposed, thereby forming the magnetic thin film on the thin film formation surface. A method for manufacturing a magnetic structure.

11. If the area of ​​the film-formed region is Sa and the area of ​​the non-film-formed region is Sb, The magnetic thin film is formed so that Sa / (Sa+Sb)≧0.

17. The method of claim 10.

12. The magnetic thin film is formed to a thickness thinner than the grain size of the rare earth magnetic powder. The method of claim 10.

13. A plurality of the magnetic thin films are arranged at predetermined intervals. The method of claim 10.

14. The predetermined interval is 450 μm or less. The method of claim 13.

15. If the outer diameter of the magnetic thin film is D and the thickness of the magnetic thin film is L, then The magnetic thin film is formed so that D / L=0.7 to 350. The method of claim 10.

16. The magnetic thin film is formed to have an outer diameter of 350 μm or less and a thickness of 100 nm or more. The method of claim 10.

17. The injection of the raw material powder toward the thin film formation surface on which the mask is superimposed is performed by a high-velocity gas stream in an inert gas atmosphere having an oxygen concentration of 1000 ppm or less. The method of claim 10.

18. The gas pressure in the high-speed gas flow is 0.5 MPa or more. The method of claim 17.

19. The gas temperature in the high-velocity gas stream is 100° C. or less. The method of claim 17.

20. The raw material powder includes a magnetic powder made of the rare earth magnet material and a grain boundary material powder made of the low melting point metal material. The method of claim 10.

21. The raw material powder contains zinc powder as the grain boundary material powder in an amount of 15 weight percent or less. The method of claim 20.

22. The zinc powder is made of zinc nanoparticles having a particle size of 1 μm or less. The method of claim 21.

23. The zinc powder is made of zinc nanoparticles having a particle size of 100 nm or less. The method of claim 22.

24. The zinc powder is made of zinc nanoparticles having a particle size of 20 nm or less. The method of claim 23.

25. The zinc powder is made of zinc nanoparticles having a particle size of 5 nm or less. The method of claim 24.

26. The rare earth magnet material is a samarium-iron-nitrogen based magnet material. The method according to any one of claims 10 to 25.

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