Particle, composite material, method for producing particle, and method for producing composite material

Abstract

To provide particles suitable for manufacturing a composite material.SOLUTION: The particle 1 is a core-shell particle having a core particle 3 and a shell layer 5 covering the core particle 3. The core particle 3 is formed of a metal particle. The shell layer 5 has an insulating layer 7 formed on the surface of the core particle 3 and an outermost layer 9 formed outside the insulating layer 7. The outermost layer 9 contains Ti (titanium).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to particles, composite materials, methods for making particles, and methods for making composite materials. [Background technology]

[0002] Conventionally, dust cores having a structure in which metal particles are isolated by ceramic are known. A capacitor with a similar structure has also been proposed. Both are produced by a method of molding core-shell type particles, in which metal particles are covered with ceramic, using a mold press. However, there were the following issues: It was difficult to mold into complex shapes or film shapes. It was also difficult to mold into large-sized products. There was also the issue of high costs because different molds were required for each product. There was also the issue of weak bonding strength between particles, making them brittle. Therefore, in order to solve at least one of the above problems, a cold spray method has been proposed in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-212466 Summary of the Invention [Problem to be solved by the invention]

[0004] However, this technology does not solve the problem of weak bonding strength between particles, making the material brittle.In addition, this technology also causes the particles to become flat, which reduces the isotropy of properties such as magnetic permeability and permittivity. The present disclosure has been made in view of the above circumstances, and aims to solve at least one of the above problems. The present disclosure can be realized in the following forms. [Means for solving the problem]

[0005] [1] a core particle made of a metal particle; an insulating layer formed on the surface of the core particle; an outermost layer formed outside the insulating layer, Particles, wherein the outermost layer contains Ti (titanium). [2] The particle according to [1], having an intermediate layer between the insulating layer and the outermost layer. [3] A composite material comprising a plurality of particles according to [1] or [2] bound together. [4] The composite material according to [3], wherein the metal particles have a flatness of 3.3 or less. [5] The composite material according to [3] or [4], wherein gaps exist between the metal particles. [6] [1] or [2], the method for producing particles, forming the outermost layer containing Ti (titanium) on the outside of the insulating layer; A method for producing particles, comprising: [7] A method for producing a composite material according to any one of [3] to [5], cold spraying the particles; A method for manufacturing a composite material, comprising: [Effects of the Invention]

[0006] According to the present disclosure, at least one of the above problems can be solved. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a schematic diagram of a cross section of a particle. [Figure 2] FIG. 2 is a schematic enlarged view of a part of the cross section of a particle. [Figure 3] FIG. 2 is a schematic diagram of a cross section of a composite material. [Figure 4] FIG. 1 is a schematic diagram illustrating cold spray. [Figure 5] These are SEM images (backscattered electron images) of particle C. The upper image shows a cross-sectional image of particle C, and the lower image shows a surface image of particle C. [Figure 6] 1 is a graph showing particle adhesion rates to a substrate by cold spraying. [Figure 7] 1 is a graph showing particle adhesion rates to a substrate by cold spraying. [Figure 8] This is an SEM image (backscattered electron image) of a cross section of a composite material. [Figure 9] This is an SEM image (backscattered electron image) of the surface of the composite material. [Figure 10] This is an SEM image (backscattered electron image) of a cross section of a composite material. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present disclosure will be described in detail below. In this specification, when a numerical range is indicated using "-", it is intended to include both the lower and upper limits unless otherwise specified. For example, the expression "10-20" includes both the lower limit "10" and the upper limit "20". In other words, "10-20" has the same meaning as "10 or more and 20 or less". Furthermore, in this specification, the upper and lower limits of each numerical range can be arbitrarily combined. Furthermore, the drawings are conceptual diagrams for explaining the disclosed contents and do not accurately depict actual dimensions.

[0009] 1. Particle 1 Particle 1 is a core-shell particle having a core particle 3 and a shell layer 5 covering the core particle 3. The core particle 3 is made of a metal particle. The shell layer 5 has an insulating layer 7 formed on the surface of the core particle 3 and an outermost layer 9 formed outside the insulating layer 7. The outermost layer 9 contains Ti (titanium). The shell layer 5 may have an intermediate layer 11 between the insulating layer 7 and the outermost layer 9.

[0010] (1) Core particle 3 The core particle 3 is made of a metal particle. The metal particles are not particularly limited. The metal particles are preferably at least one selected from the group consisting of iron particles, nickel particles, cobalt particles, Fe—Si alloy particles, Fe—Si—Cr alloy particles, Fe—Si—Al alloy particles (Sendust), Ni—Fe alloy particles (Permalloy), Ni—Fe—Mo alloy particles (Supermalloy), Fe-based amorphous alloy particles, Fe—Co alloy particles, aluminum alloy particles, copper alloy particles, zinc alloy particles, and tin alloy particles. In consideration of the application of particles 1 to powder magnetic cores, iron particles are preferred as the metal particles. The particle diameter (D50) (median diameter) of the core particle 3 is not particularly limited. From the viewpoint of ensuring sufficient bonding strength between particles 1 in the composite material 15 produced by cold spraying, the particle diameter (D50) of the core particle 3 is preferably 5 μm or more and 150 μm or less, more preferably 10 μm or more and 100 μm or less, and even more preferably 20 μm or more and 80 μm or less. The particle diameter (D50) can be measured by laser diffraction.

[0011] (2) Shell layer 5 The shell layer 5 has an insulating layer 7 formed on the surface of the core particle 3 and an outermost layer 9 formed outside the insulating layer 7 .

[0012] (2.1) Insulating layer 7 The insulating layer 7 is not particularly limited. The insulating layer 7 is preferably an oxide of the metal contained in the core particle 3, as this is relatively easy to form. For example, when the core particle 3 is an iron particle, the insulating layer 7 is preferably an iron oxide layer. In this case, the insulating layer 7 can be formed by oxidizing the surface of the core particle 3. From the viewpoint of ensuring sufficient insulation, the thickness of insulating layer 7 is preferably 50 nm or more, more preferably 100 nm or more, and even more preferably 200 nm or more. On the other hand, from the viewpoint of fully exhibiting the inherent functions of core particle 3, the thickness is preferably 1000 nm or less, more preferably 800 nm or less, and even more preferably 600 nm or less. From these viewpoints, the thickness of insulating layer 7 is preferably 50 nm or more and 1000 nm or less, more preferably 100 nm or more and 800 nm or less, and even more preferably 200 nm or more and 600 nm or less. The thickness of insulating layer 7 can be determined by observing the cross section of particle 1 with a FIB-SEM (dual beam scanning electron microscope).

[0013] (2.2) Outermost layer 9 The outermost layer 9 contains Ti (titanium). When the outermost layer 9 contains Ti, the adhesion rate of the particles 1 to the substrate 21 is improved during film formation by cold spray. When the outermost layer 9 contains Ti, the collision conditions during film formation by cold spray can be made slower. The outermost layer 9 may contain a component other than Ti (titanium), such as Al (aluminum), Ni (nickel), or Zn (zinc). The outermost layer 9 may be made of Ti (titanium). From the viewpoint of improving the adhesion rate of the particle 1 to the substrate 21, the thickness of the outermost layer 9 is preferably 5 nm or more, more preferably 20 nm or more, and even more preferably 50 nm or more. On the other hand, from the viewpoint of fully exhibiting the inherent functions of the core particle 3, the thickness is preferably 300 nm or less, more preferably 200 nm or less, and even more preferably 100 nm or less. From these viewpoints, the thickness of the outermost layer 9 is preferably 5 nm or more and 300 nm or less, more preferably 20 nm or more and 200 nm or less, and even more preferably 50 nm or more and 100 nm or less. The thickness of the outermost layer 9 can be determined by observing the cross section of the particle 1 with a FIB-SEM (dual beam scanning electron microscope).

[0014] (2.3) Middle Layer 11 (Optional Requirement) The shell layer 5 may have an intermediate layer 11 between the insulating layer 7 and the outermost layer 9. The provision of the intermediate layer 11 improves the plastic deformation characteristics of the particles 1. That is, when the particles 1 are collided with the substrate 21 by cold spraying, the intermediate layer 11 is mainly plastically deformed, and the particles 1 are deposited, forming a composite material 15. From the viewpoint of imparting plastic deformation properties to the particle 1, the intermediate layer 11 is preferably at least one selected from the group consisting of a Ni (nickel) layer, a Zn (zinc) layer, an Al (aluminum) layer, and a Cu (copper) layer. From the viewpoint of improving the adhesion rate of the particle 1 to the substrate 21, the thickness of the intermediate layer 11 is preferably 50 nm or more, more preferably 100 nm or more, and even more preferably 500 nm or more. On the other hand, from the viewpoint of fully exhibiting the inherent functions of the core particle 3, the thickness is preferably 5000 nm or less, more preferably 4000 nm or less, and even more preferably 3000 nm or less. From these viewpoints, the thickness of the intermediate layer 11 is preferably 50 nm or more and 5000 nm or less, more preferably 100 nm or more and 4000 nm or less, and even more preferably 500 nm or more and 3000 nm or less. The thickness of the intermediate layer 11 can be determined by observing the cross section of the particle 1 with a FIB-SEM (dual beam scanning electron microscope).

[0015] (3) Effects of Particle 1 of the Present Disclosure According to the particles 1 of the present disclosure, a composite material 15 having strong bonding strength between the particles 1 can be produced. According to the particles 1 of the present disclosure, by colliding and depositing the particles 1 on a substrate 21 by cold spraying, a composite material 15 having strong bonding strength between the particles 1 can be produced. According to the particles 1 of the present disclosure, even in low-speed collisions in the cold spray method, the adhesion rate of the particles 1 to the substrate 21 is high. Therefore, flattening of the particles 1 in the composite material 15 can be suppressed, and a decrease in the isotropy of the properties of the composite material 15 can be suppressed. The particles 1 of the present disclosure can be suitably used in the cold spray method. This makes it possible to produce a complex-shaped or large-sized composite material 15. The use of the cold spray method eliminates the need for a mold for each part, as is required in conventional die pressing. The particles 1 of the present disclosure can be suitably used in the cold spray method, and can therefore be formed into complex shapes, film shapes, and the like that cannot be realized by die pressing. The particles 1 of the present disclosure can be suitably used in a cold spray method, and therefore can be used to coat or build up other members. The particles 1 of the present disclosure can be suitably used in the cold spray method, enabling product designs that were previously impossible. For example, innovative designs such as designs using AI can be realized.

[0016] 2. Composite materials 15 The composite material 15 is formed by bonding a plurality of particles 1. Since the composite material 15 is formed by bonding core particles 3 made of metal particles, it is useful for applications such as dust cores, grain boundary insulating capacitors, soft magnetic core materials, and permanent magnet materials.

[0017] From the viewpoint of ensuring isotropy of the magnetic properties, the metal particles contained in the composite material 15 preferably have a flatness of 3.3 or less, more preferably 2.9 or less, and even more preferably 2.5 or less. Here, a method for measuring the flatness of the metal particles contained in the composite material 15 will be described. The flatness is determined by calculating the flatness from particles observed by FE-SEM (e.g., JSM-6330F) in a cross section of the composite material 15. Specifically, attention is focused on a plurality of metal particles that can be observed without chipping within a predetermined observation field (e.g., 200 μm × 200 μm). The major axis and minor axis of each metal particle are measured, and the major axis / minor axis ratio is calculated to determine the flatness. Note that the major axis refers to the longest diameter in the cross section of the metal particle, and the minor axis refers to the longest diameter perpendicular to the major axis. The flatness in this disclosure is then determined by arithmetically averaging the flatness of each particle. The flatness of each particle can be determined using common image analysis software.

[0018] It is preferable that gaps 17 exist between the metal particles in the composite material 15. The presence of the gaps 17 tends to lower the Young's modulus of the composite material 15, making it more susceptible to elastic deformation. The gaps 17 can be confirmed by observing the cross section of the composite material 15 with an FE-SEM (for example, JSM-6330F). There is no particular limitation on the size of gap 17. From the viewpoint of ensuring sufficient strength of composite material 15, gap 17 preferably has a cross-sectional area smaller than the average cross-sectional area of ​​the metal particles observed in the cross section of composite material 15. Here, a method for measuring the average cross-sectional area of ​​the metal particles contained in the composite material 15 will be described. The average cross-sectional area is determined by observing the cross-section of the composite material 15 using an FE-SEM (e.g., JSM-6330F) and calculating the average cross-sectional area from the particles. Specifically, attention is focused on a plurality of metal particles that can be observed without missing particles within a predetermined observation field (e.g., 200 μm × 200 μm). The cross-sectional area of ​​each metal particle is measured. The average cross-sectional area in the present disclosure is then determined by arithmetically averaging the cross-sectional areas of each particle. The cross-sectional area of ​​each particle can be determined using common image analysis software.

[0019] The composite material 15 of the present disclosure has strong bonding strength between the particles 1 . The composite material 15 of the present disclosure can be produced by depositing particles 1 onto a substrate 21 by cold spraying. The composite material 15 of the present disclosure is easy to manufacture because it can be produced even with the low impact velocity of the cold spray process. When the composite material 15 of the present disclosure is produced, the adhesion rate of the particles 1 to the substrate 21 is high, so that the production cost can be reduced. When the composite material 15 of the present disclosure is manufactured, the particles 1 in the composite material 15 can be prevented from being flattened by employing low-speed collisions, and the deterioration of the isotropy in the properties of the composite material 15 can be prevented. The composite material 15 of the present disclosure can be manufactured by a cold spray method. This makes it possible to manufacture a complex-shaped or large-sized composite material 15. By using the cold spray method, there is no need for a mold for each part, as is required in conventional die pressing methods. The composite material 15 of the present disclosure can be produced by the cold spray method, and therefore can be made into complex shapes and film shapes that cannot be achieved by die pressing. The composite material 15 of the present disclosure can be manufactured by the cold spray method, enabling previously unattainable product designs. For example, innovative designs such as AI-based designs can be realized.

[0020] 3. Method for producing particle 1 (1) Preferred Method for Producing Particles 1 The method for producing the particles 1 is not particularly limited. The method for producing the particle 1 preferably includes a step of forming an outermost layer 9 containing Ti (titanium) on the outside of the insulating layer 7. In this step, a known method such as sputtering or CVD is used. Here, a preferred embodiment of the method for producing the particles 1 will be described. The method for producing particle 1 is as follows: an insulating layer forming step of forming an insulating layer 7 by oxidizing the surface of the core particle 3; an intermediate layer forming step of forming an intermediate layer 11 on the core particle 3 on which the insulating layer 7 has been formed; It is preferable to further include an outermost layer forming step of forming an outermost layer 9 containing Ti on the core particle 3 on which the intermediate layer 11 has been formed.

[0021] In the insulating layer forming step, the particles 1 are preferably heat-treated in the presence of oxygen. The conditions for the heat treatment are not particularly limited. From the viewpoint of ensuring a sufficient thickness of the oxide film to be formed, the maximum temperature in the heat treatment is preferably higher than 300°C, more preferably 350°C or higher, and even more preferably 380°C or higher. On the other hand, from the viewpoint of suppressing adhesion between the particles 1, the maximum temperature is preferably lower than 500°C, more preferably 450°C or lower, and even more preferably 410°C or lower. From these viewpoints, the maximum temperature in the heat treatment is preferably higher than 300°C and lower than 500°C, more preferably 350°C or higher and 450°C or lower, and even more preferably 380°C or higher and 410°C or lower.

[0022] In the intermediate layer forming step, a metal film is preferably formed by electroless plating on the surface of the core particle 3 on which the insulating layer 7 has been formed. An example of electroless plating is electroless nickel plating (powder plating).

[0023] In the outermost layer forming step, as described above, known techniques such as sputtering and CVD are employed.

[0024] (2) Effects of the method for producing particle 1 of the present disclosure According to the preferred manufacturing method of the present disclosure, particles 1 suitable as raw materials for composite material 15 having strong bonding strength between particles 1 can be manufactured. According to the preferred manufacturing method of the present disclosure, particles 1 suitable as a raw material for a composite material 15 manufactured using cold spraying can be manufactured.

[0025] 4. Manufacturing method of composite material 15 The method for producing the composite material 15 is not particularly limited. The composite material 15 preferably includes a step of cold spraying the particles 1. Cold spraying is a method of forming a film by colliding metal powder in a solid state against a target at supersonic speed using an inert gas as the working medium. Because the raw material powder is not melted, a film that is not altered by oxidation or heat is obtained. Specifically, a gas flow is accelerated to supersonic speed by a tapered-divergent nozzle with a throat of the cold spray device. When the particles 1 are placed in the gas flow heated by a heater, they are accelerated and heated, colliding with and adhering to the substrate 21 in a solid state. According to the preferred manufacturing method of the present disclosure, a composite material 15 having strong bonding strength between particles 1 can be manufactured. According to a preferred manufacturing method of the present disclosure, the particles 1 are deposited by colliding with the substrate 21 by cold spraying, thereby producing a composite material 15 having strong bonding strength between the particles 1. According to the preferred manufacturing method of the present disclosure, even with low-speed collisions in the cold spray method, the adhesion rate of the particles 1 to the substrate 21 can be increased. Therefore, flattening of the particles 1 in the composite material 15 can be suppressed, and a decrease in the isotropy of the properties of the composite material 15 can be suppressed. [Example]

[0026] The present disclosure will be explained more specifically with reference to examples.

[0027] 1. Particle Preparation Particles A, B, C, and D were prepared. Particle C corresponds to the example. (1) Preparation of Particle C Iron particles were used as the core particles 3. The iron particles were gas atomized powder made of pure Fe and having a median particle size D50 of approximately 75 μm. The iron particles used had passed through a sieve with a mesh size of 150 μm. The insulating layer 7 was an oxide film. The oxide film was formed by heat treating the iron particles in air. A rotary kiln was used for the heat treatment. The air flow was set to 1 L / min, and the iron particles with the oxide film formed on their surfaces were held in the rotary kiln at a maximum temperature of 400°C for 1 hour. The heat treatment was performed under the conditions of a temperature rise rate of 2.5°C / min, a temperature drop rate of 2.5°C / min, and a rotation speed of 1.5 rpm. The intermediate layer 11 was a Ni film. The Ni film was formed by electroless nickel plating (powder plating). The outermost layer 9 was a Ti film. The Ti film was formed by sputtering metal titanium (powder sputtering). Iron particles with oxide and Ni films on their surfaces were flowed in a rotating barrel and sputtered to form the film. The film formation time was 7 hours. In this way, the following particle C was prepared. Figure 5 shows an SEM image of particle C. The upper image in Figure 5 shows an SEM image of the cross section. The lower image in Figure 5 shows an SEM image of the surface. <Particle C> Core particle 3: Iron particle Insulation layer 7: 0.4 μm Intermediate layer 11: Ni film (2.5μm) Outermost layer 9:Ti film (0.1μm)

[0028] (2) Preparation of Particle B Particles B were produced in the same manner as particles C, except that the outermost layer 9 was not formed. <Particle B> Core particle 3: Iron particle Insulation layer 7: 0.4 μm Intermediate layer 11: Ni film (2.5μm) Outermost layer 9: None

[0029] (3) Preparation of Particle A Particles A were produced in the same manner as particles B, except that the Ni film of the intermediate layer 11 was set to 0.5 μm. <Particle A> Core particle 3: Iron particle Insulation layer 7: 0.4 μm Intermediate layer 11: Ni film (0.5μm) Outermost layer 9: None

[0030] (4) Preparation of Particle D Iron particles were used as the core particles 3. The iron particles were gas atomized powder made of pure Fe and having a median particle size D50 of approximately 75 μm. The iron particles used had passed through a sieve with a mesh size of 150 μm. None of the insulating layer 7, intermediate layer 11, and outermost layer 9 was formed. <Particle D> Core particle 3: Iron particle Insulation layer 7: None Middle layer 11: None Outermost layer 9: None

[0031] 2. Composite materials 15 (1) Preparation of composite material 15 Particles A, B, C, and D were used. Composite material 15 was produced using the following cold spray device. <Cold spray device> Equipment: Plasma Giken Kogyo cold spray equipment PCS-1000V2 Nozzle: Φ2.8mm longer Gas type: Nitrogen gas Gas temperature: 800℃ Gas pressure: 3MPa or 5MPa Distance between gun and substrate: 30, 55, 80, 130, 180 mm Powder supply rate: Estimated 30 g / min (powder supply device rotation speed: 1.0 rpm) Gun movement speed (robot moves gun left and right): 300 mm / sec (In this case, the film was formed by moving the nozzle back and forth 20 times (40 passes) on the same line.) Projection angle to the substrate: 90° Base material: Aluminum A1050P-H24, no surface treatment. (The surface has not been roughened by blasting, as is often done with thermal spraying.) Base material size: 100m x 20mm x 2mm thick

[0032] (2)Various measurement results (2.1) Particle adhesion rate to substrate Figure 6 is a graph showing the particle adhesion rate when the gun-to-substrate distance is changed using various types of particles A, B, C, and D. The particle adhesion rate is the mass of particles that adhere to the substrate relative to the mass of cold-sprayed particles, expressed as a percentage. For example, an adhesion rate of 100% indicates that all of the cold-sprayed particles adhered to the substrate. An adhesion rate of 0% indicates that none of the cold-sprayed particles adhered to the substrate. Figure 6 shows the adhesion rate under high-speed conditions with a gas pressure of 5 MPa. Under these high-speed conditions, particles B, C, and D all had higher adhesion rates than particle A. Figure 7 shows the deposition rate under low-speed conditions with a gas pressure of 3 MPa. Under these low-speed conditions, when particles B and D were used, the deposition rate was not significantly improved compared to particle A. This is thought to be because the bond strength between particles is weak and brittle at low speeds. On the other hand, even under low-speed conditions, when particle C was used, the deposition rate was significantly improved compared to particle A. Furthermore, under low-speed conditions, when particle C was used, the deposition rate was significantly improved compared to particles B and D. Thus, it was found that particle C, which has an outermost layer 9 of Ti film, significantly improved the deposition rate. It is presumed that the chemical activity of Ti in the outermost layer 9 contributed to this result. From these results, it is presumed that the outermost layer 9 of the particles C contains Ti, which strengthens the bond strength between the particles C in the composite material 15, resulting in an improved adhesion rate.

[0033] (2.2) State change of composite material 15 under cold spray conditions We compared the cross-sectional SEM images of composite material 15 produced using particle C while keeping the gas pressure constant and varying the gun-substrate distance. The results showed that the longer the gun-substrate distance, the more voids there were. Furthermore, the longer the gun-substrate distance, the more suppressed the flattening of particle C in composite material 15. Using particle C, we compared SEM images of the cross sections of composite material 15 produced when the gun-substrate distance was fixed and the gas pressure was changed. The results showed that the weaker the gas pressure, the more voids there were. In addition, the weaker the gas pressure, the more the flattening of particle C in composite material 15 tended to be suppressed. These results show that the weaker the gas pressure and the longer the substrate-to-substrate distance, the more voids there were in composite material 15. In addition, the weaker the gas pressure and the longer the substrate-to-substrate distance, the more the flattening of particles C in composite material 15 tended to be suppressed.

[0034] (2.3) Observation of the state of composite material 15 The cross section and surface of composite material 15, which was produced using particle C under conditions of a gas pressure of 3 MPa and a gun-to-substrate distance of 180 mm, were observed. Other production conditions were the same as those described in the "Cold spray apparatus" section of "2. Composite material 15 (1) Production of composite material 15" above.

[0035] An SEM image of a cross section of composite material 15 is shown in Figure 8. An SEM image of the surface of composite material 15 is shown in Figure 9. Figure 10 is an enlarged SEM image of a part of Figure 8. 8, 9, and 10, it was confirmed that the core-shell structure of particle C was maintained in composite material 15 produced using particle C. In FIG. 10, it can be clearly observed that the core-shell structure having core particle 3 and shell layer 5 was maintained.

[0036] 3. Effects of the Example The particles C of this example can be formed into a complex shape or a film shape. The particles C of this example can be used to form large-sized composite materials. Since the particles C of this example can be applied to cold spraying, a mold for each part is not required. In the particles C of this example, the outermost layer 9 contains Ti, and therefore the bonding strength between the particles C in the composite material 15 is strong.

[0037] The present invention is not limited to the above-described embodiments, and various modifications and variations are possible within the scope of the claims of the present invention. [Explanation of symbols]

[0038] 1...particle 3...core particle 5...shell layer 7...insulating layer 9...outermost layer 11...Middle class 15…Composite materials 17...Gap 21...Base material

Claims

1. a core particle made of a metal particle; an insulating layer formed on the surface of the core particle; an outermost layer formed outside the insulating layer, Particles, wherein the outermost layer contains Ti (titanium).

2. The particle according to claim 1 , further comprising an intermediate layer between the insulating layer and the outermost layer.

3. A composite material comprising a plurality of particles according to claim 1 or 2 bound together.

4. The composite material according to claim 3 , wherein the metal particles have a flatness of 3.3 or less.

5. The composite material of claim 3 , wherein interstices exist between the metal particles.

6. A method for producing the particles according to claim 1 or claim 2, comprising: forming the outermost layer containing Ti (titanium) on the outside of the insulating layer; A method for producing particles, comprising:

7. A method for producing the composite material according to claim 3, comprising: cold spraying the particles; A method for manufacturing a composite material, comprising:

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