Composite material

Abstract

A composite material comprises a dispersion material having a thermal conductivity of 100 W / K ⋅ m or above, and an insulator interposed between the dispersion materials. For example, the dispersion material is an aluminum-based metal powder. For example, the insulator is an oxide or a resin having a glass transition point equal to or lower than the melting point of the dispersion material. For example, the electrical conductivity of the composite material is 0.5 × 106 S / m or below.

Description

Composite material Cross-reference to related applications

[0001] This international application claims priority based on Japanese Patent Application No. 2024-174351, which was filed with the Japan Patent Office on October 3, 2024, and incorporates by reference the entire contents of Japanese Patent Application No. 2024-174351 into this international application.

[0002] This disclosure relates to a composite material.

[0003] Patent Documents 1 and 2 describe powder-compressed cores. A powder-compressed core is obtained by compression molding iron-based powder together with a binder containing resin or ceramics.

[0004] JP-A-2011-216745 JP-A-2016-12671

[0005] In recent years, the development of mobility powered by motors such as electric vehicles and drones has been booming. Along with this, the output of motors has been increasing and the weight has been decreasing. With the increase in the output of motors, the need to improve the thermal conductivity of the materials constituting the motors has been increasing. Currently, CFPR may be adopted as a material for structural members such as motor cases for the purpose of weight reduction, but materials with even higher thermal conductivity are required.

[0006] Also, around a rotating motor, the change in magnetic flux is intense. If a material with high electrical conductivity is around the motor, a large amount of induced current will be generated, which is not preferable because it becomes a resistance to the rotation of the motor or a cause of heat generation. Therefore, it is preferable that the electrical conductivity of the materials constituting the motor is low.

[0007] Since the powder-compressed cores described in Patent Documents 1 and 2 have low thermal conductivity, they are not suitable for uses other than motor cores. In one aspect of this disclosure, it is preferable to provide a composite material having high thermal conductivity and low electrical conductivity.

[0008] One aspect of this disclosure is a composite material including a dispersion material having a thermal conductivity of 100 W / K·m or more and an insulator interposed between the dispersion materials. The composite material, which is one aspect of this disclosure, has high thermal conductivity and low electrical conductivity.

[0009] This is an explanatory diagram showing the composition of the composite material and the manufacturing method. It is a perspective view showing the configuration of the equipment for heating and compressing the raw materials. It is a side cross-sectional view showing the configuration of the equipment during heating and compression.

[0010] 1... Composite material, 3... Dispersant, 4... Insulator powder, 5... Insulator, 11... Apparatus, 13... Cylindrical die, 13A... Inner circumference, 13B... Outer circumference, 15... First cylindrical bunch, 17... Second cylindrical bunch, 19... Third cylindrical bunch, 21... Raw material

[0011] Exemplary embodiments of the present disclosure will be described with reference to the drawings. <First Embodiment> 1. Composite Material 1 As shown in S_C in Diagram 1, the composite material 1 comprises a dispersant 3 and an insulator 5. The insulator 5 is interposed between the dispersants 3. The thermal conductivity of the dispersant 3 is 100 W / K·m or more.

[0012] The dispersant 3 is, for example, a metal powder. Examples of metals include aluminum, copper, silver, gold, and alloys of two or more of these. The dispersant 3 is, for example, an aluminum-based metal powder. Examples of aluminum-based metal powders include aluminum atomized powder and aluminum cutting chips. The average particle size of the dispersant 3 is preferably 10 μm or more and 500 μm or less. The method for measuring the average particle size is the mesh passage method.

[0013] The insulator 5 is, for example, a low-melting-point ceramic, oxide, silicone, or resin. The glass transition temperature of the insulator 5 is, for example, below the melting point of the dispersant 3. The insulator 5 is, for example, a low-melting-point ceramic, oxide, silicone, or resin whose glass transition temperature is below the melting point of the dispersant 3.

[0014] The electrical conductivity of composite material 1 is, for example, 0.5 × 10⁻⁶ ６ It is less than or equal to S / m. One way to reduce the electrical conductivity of composite material 1 is to increase the amount of insulator 5. The thermal conductivity of composite material 1 is, for example, 8 W / K·m or more, and preferably 10 W / K·m or more. One way to increase the thermal conductivity of composite material 1 is to decrease the amount of insulator 5.

[0015] The density of composite material 1 is, for example, 2.7 g / cm³.３ The following are methods for reducing the density of composite material 1: reducing the pressure applied during the manufacturing of composite material 1, and increasing the diameter of the dispersant 3.

[0016] When the mass of the dispersant 3 is 100 parts by mass, the mass of the insulator 5 is preferably 30 parts by mass or more and 100 parts by mass or less. When the mass ratio of the dispersant 3 to the insulator 5 is within this range, the shape of the composite material 1 is more likely to be stable. The composite material 1 can be used, for example, as a material for structural members of a mobility motor. Examples of structural members include the cover for the entire motor, the fixing plate for the stator, the fixing plate for the rotor, and so on.

[0017] 2. Method for Manufacturing Composite Material 1 Composite material 1 can be manufactured, for example, by the following method. First, raw materials 21 shown in S_A in Figure 1 are prepared. Raw materials 21 include a dispersant 3 and an insulating powder 4. The insulating powder 4 becomes an insulator 5 when it is later melted. The insulating powder 4 functions as a binder. The insulating powder 4 is, for example, a powder of a low melting point ceramic, oxide, silicone, or resin. For example, the glass transition point of the insulating powder 4 is lower than the melting point of the dispersant 3. The average particle size of the insulating powder 4 is, for example, 1 μm or more and 30 μm or less.

[0018] The raw material 21 is, for example, a powder. For example, the raw material 21 can be prepared by mixing the dispersant 3 and the insulating powder 4. For mixing, for example, a mortar and pestle can be used. For example, in the raw material 21, the dispersant 3 and the insulating powder 4 are uniformly dispersed.

[0019] Next, the raw material 21 is heated and compressed. When the raw material 21 is heated and compressed, the insulating powder 4 melts and becomes a liquid insulating material 5, as shown in S_B and S_C in Figure 1. When the raw material 21 is heated and compressed, for example, the dispersant 3 does not melt. The liquid insulating material 5 fills the spaces between the dispersant 3 particles.

[0020] As a method for heating and compressing the raw material 21, for example, there is a method using the apparatus 11 shown in Figures 2 and 3, and a hot press apparatus (not shown). Apparatus 11 comprises a cylindrical die 13, a first cylindrical bunch 15, a second cylindrical bunch 17, and a third cylindrical bunch 19.

[0021] The cylindrical die 13 is a hollow cylindrical component. The cylindrical die 13 is composed of an inner circumference 13A and an outer circumference 13B. The outer circumference 13B is located further outward than the inner circumference 13A. The inner circumference 13A is made of graphite. The outer circumference 13B is made of SKD61 steel.

[0022] The first cylindrical bunch 15, the second cylindrical bunch 17, and the third cylindrical bunch 19 are each cylindrical members. The diameters D of the first cylindrical bunch 15, the second cylindrical bunch 17, and the third cylindrical bunch 19 are close to, and slightly smaller than, the inner diameter of the cylindrical die 13. The first cylindrical bunch 15 and the second cylindrical bunch 17 are made of graphite. The third cylindrical bunch 19 is made of SKD61 steel.

[0023] The method for heating and compressing the raw material 21 using the apparatus 11 and the hot press apparatus is as follows. First, as shown in Figure 3, the cylindrical die 13 is positioned so that its axial direction coincides with the vertical direction. Next, the first cylindrical bunch 15 is placed inside the cylindrical die 13. The thickness direction of the first cylindrical bunch 15 coincides with the vertical direction.

[0024] Next, the raw material 21 is placed on top of the first cylindrical bunch 15. Then, the second cylindrical bunch 17 is placed on top of the raw material 21. The thickness direction of the second cylindrical bunch 17 coincides with the vertical direction. The raw material 21 is sandwiched vertically between the first cylindrical bunch 15 and the second cylindrical bunch 17. Also, the outer circumference of the raw material 21 faces the inner circumference 13A.

[0025] Next, the third cylindrical bunch 19 is placed on top of the second cylindrical bunch 17. The thickness direction of the third cylindrical bunch 19 coincides with the vertical direction. At this time, the entirety of the first cylindrical bunch 15, the raw material 21, and the second cylindrical bunch 17 are housed inside the cylindrical die 13. A portion of the lower part of the third cylindrical bunch 19 is housed inside the cylindrical die 13, while the other portion protrudes above the cylindrical die 13.

[0026] Next, the apparatus 11 is placed inside the hot press apparatus. The hot press apparatus heats the apparatus 11 while pressing the third cylindrical bunch 19 downwards, thereby heating and compressing the raw material 21. Heating and compression may be performed under vacuum or under atmospheric pressure. When the raw material 21 is heated and compressed, the insulating powder 4 melts and becomes a liquid insulating material 5, as shown in S_B and S_C in Figure 1. When the raw material 21 is heated and compressed, the dispersant 3 does not melt. The liquid insulating material 5 fills the spaces between the dispersant 3 particles.

[0027] Next, the apparatus 11 is cooled. At this time, the insulator 5 solidifies, and the composite material 1 is completed. Cooling may be carried out under vacuum or under atmospheric pressure. For example, cooling is performed by natural cooling. Next, the apparatus 11 is removed from the hot press apparatus, and then the composite material 1 is removed from the apparatus 11. Through the above steps, the composite material 1 shown in S_C in Figure 1 is obtained.

[0028] 3. Effects of Composite Material 1 (1A) Composite material 1 has high thermal conductivity and low electrical conductivity. Because composite material 1 has low electrical conductivity, even when composite material 1 is installed in a place where the magnetic flux changes rapidly, such as around a rotating motor, it is difficult for induced current to be generated in composite material 1. Because it is difficult for induced current to be generated in composite material 1, energy loss can be suppressed.

[0029] (1B) For example, the density of composite material 1 can be reduced. When the density of composite material 1 is low, composite material 1 can be used in a mobile body. Examples of mobile bodies include HAPS (flying base stations), eVTOL (flying cars), electric vehicles, drones, etc. <Examples> 1. Manufacturing of samples S1 to S7 Samples S1 to S7 were each manufactured as follows. First, raw material 21 was prepared. In the case of sample S1, raw material 21 consisted only of aluminum powder. In the case of samples S2 to S6, raw material 21 was a mixture of aluminum powder and low-melting-point ceramic powder. In the case of samples S2 to S6, the mass ratio of aluminum powder to low-melting-point ceramic powder was as shown in Table 1.

[0030] In the case of samples S2 to S6, aluminum powder and low-melting-point ceramic powder were mixed in a mortar for about 5 minutes to prepare the raw material 21. By mixing, the low-melting-point ceramic powder was thoroughly coated onto the surface of the aluminum powder. After mixing, there were no areas in the raw material 21 where the silver color of the aluminum powder and the white color of the low-melting-point ceramic powder were separated, and they were uniformly mixed. This indicated that the aluminum powder and low-melting-point ceramic powder were thoroughly mixed.

[0031] In the case of sample S7, the raw material 21 consisted solely of low-melting-point ceramic powder. The purity of the aluminum powder contained in the raw material 21 of samples S1 to S6 was 99% or higher. The particle size of the aluminum powder was 300 μm or less. The thermal conductivity of the aluminum powder was 200 W / K·m. The melting point of the aluminum powder was 660.3°C. The aluminum powder corresponds to the dispersant 3.

[0032] The low-melting-point ceramic powder contained in the raw material 21 of samples S2 to S7 was TOMATEC TMS-490. The low-melting-point ceramic powder corresponds to the insulating powder 4.

[0033] Next, the raw material 21 was heated and compressed using the apparatus 11 shown in Figures 2 and 3 and a vacuum hot press apparatus manufactured by Daiya Vacuum, in the manner described above. The inner diameter of the cylindrical die 13 was 25 mm, the outer diameter was 100 mm, and the height was 70 mm. The diameters D of the first cylindrical bunch 15, the second cylindrical bunch 17, and the third cylindrical bunch 19 were each 70 mm. The thicknesses of the first cylindrical bunch 15, the second cylindrical bunch 17, and the third cylindrical bunch 19 were each 15 mm.

[0034] During the heat compression process, the temperature inside the vacuum hot press apparatus was raised to 550°C over 30 minutes and maintained at 550°C for 1 hour. During the heat compression process, a pressure of 1 ton was applied to the apparatus 11 for 1.5 hours. When heat compression was performed, in the case of samples S2 to S7, the low-melting-point ceramic powder melted and became an insulator 5.

[0035] Next, the apparatus 11 inside the vacuum hot press apparatus was allowed to cool naturally under vacuum. When cooled, the insulator 5, which had been molten, solidified in the case of samples S2 to S7. Next, the apparatus 11 was removed into the atmosphere, and then samples S1 to S7 were removed from the apparatus 11. Samples S1 to S7 were obtained through the above steps.

[0036] In the case of sample S1, it easily crumbled when removed from the apparatus 11 after compaction. Compaction refers to heating, compression, and subsequent cooling. In the case of samples S2 to S3, the molded body after compaction crumbled without maintaining its shape. In the case of samples S4 to S6, the molded body after compaction maintained its shape without crumbling. Samples S4 to S6 correspond to composite material 1. In the case of sample S7, it shattered into pieces when removed from the apparatus 11, making it impossible to obtain a molded body.

[0037] 2. Manufacturing of Samples S8 and S9 A1050 rolled sheet was used as Sample S8. An acrylic sheet was used as Sample S9.

[0038] 3. For each of the evaluation samples S4 to S6 of the samples S1 to S9, the density, electrical conductivity, and thermal conductivity were measured. Also, for each of the samples S8 and S9, the density and electrical conductivity were measured. Further, for each of the samples S1 to S3, the electrical conductivity was measured. The measurement results are shown in Table 1. The thermal conductivities of the samples S8 and S9 shown in Table 1 are literature values.

[0039] The method for measuring the density was as follows. The mass of the sample was measured with an electronic balance. Also, the diameter and thickness of the sample were measured with a micrometer, and the volume of the sample was calculated based on the diameter and thickness. Finally, the density of the sample was calculated from the mass and volume of the sample.

[0040] The electrical conductivity was measured using a conductivity meter (Sigma Test) manufactured by Nippon Felster. The frequency in the measurement was 480 kHz. The size of the test piece used in the measurement was φ25 mm × t1.5 mm. The thermal conductivity was measured by the laser flash method.

[0041] As shown in Table 1, in samples S4 to S6, the density was low, the electrical conductivity was low, and the thermal conductivity was high. The electrical conductivity of samples S4 to S6 was 0.5 × 10 ６ S / M or less, which was the measurement limit. The reason for the low electrical conductivity in samples S4 to S6 is presumed to be that ceramic is interposed between the aluminum particles constituting the aluminum powder, insulating the aluminum particles from each other.

[0042] When measuring the electrical conductivity of the part that barely maintained its shape among samples S1 to S3, it was 0.5 × 10 ６ S / M or more. The reason for this is presumed to be that the ceramic did not sufficiently spread between the aluminum particles and sufficient insulation was not achieved. In sample S8, the electrical conductivity was high. In sample S9, the thermal conductivity was low. <Other Embodiments> The embodiments of the present disclosure have been described above, but the present disclosure is not limited to the above-described embodiments and can be implemented in various modifications.

[0043] (1) The form of the insulator powder 4 contained in the raw material 21 may be in a mesh shape or a non-woven fabric shape.

[0044] (2) The functions of one component in each of the above embodiments may be shared by a plurality of components, or the functions of a plurality of components may be exerted by one component. Also, a part of the configuration of each of the above embodiments may be omitted. Further, at least a part of the configuration of each of the above embodiments may be added to, replaced with, etc. the configuration of other above embodiments.

[0045] (3) In addition to the composite material 1 described above, the present disclosure can also be realized in various forms such as a system having the composite material 1 as a component, a manufacturing method of the composite material 1, etc. [Technical idea disclosed in this specification] [Item 1] A composite material including a dispersion material having a thermal conductivity of 100 W / K·m or more and an insulator interposed between the dispersion materials. [Item 2] The composite material according to Item 1, wherein the insulator is an oxide or a resin having a glass transition point not higher than the melting point of the dispersion material. [Item 3] The composite material according to Item 1 or 2, having an electric conductivity of 0.5×10 ６ [[ID=​​

Claims

1. A composite material comprising a dispersant having a thermal conductivity of 100 W / K·m or more, and an insulator interposed between the dispersants.

2. A composite material according to claim 1, wherein the insulator is an oxide or resin whose glass transition temperature is below the melting temperature of the dispersant.

3. A composite material according to claim 1 or 2, wherein the electrical conductivity is 0.5 × 10 ６ Composite materials with a density of S / m or less.

4. A composite material according to claim 1 or 2, wherein the thermal conductivity is 8 W / K·m or more.

5. A composite material according to claim 1 or 2, wherein the density is 2.7 g / cm³. ３ The following are composite materials.

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