composite materials

Abstract

To provide a composite material having high thermal conductivity and low electrical conductivity. [Solution] The composite material comprises dispersed materials with a thermal conductivity of 100 W / K·m or more and an insulator interposed between the dispersed materials. For example, the dispersed materials are aluminum-based metal powders. For example, the insulator is an oxide or resin whose glass transition point is equal to or lower than the melting point of the dispersed materials. For example, the electrical conductivity of the composite material is 0.5×10 6 S / m or less.

Description

[Technical Field]

[0001] The present disclosure relates to composite materials. [Background technology]

[0002] Powder magnetic cores are described in Patent Documents 1 and 2. Powder magnetic cores are made by compressing and molding iron-based powder together with a binder containing resin and ceramics. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-216745 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-12671 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the development of motor-powered mobility such as electric vehicles and drones has become more active. Accordingly, motors are becoming more powerful and lighter. As motors become more powerful, there is a growing need to improve the thermal conductivity of the materials that make up the motors. Currently, CFRP is sometimes used as a material for structural components such as motor cases to reduce weight, but materials with even higher thermal conductivity are needed.

[0005] In addition, magnetic flux changes drastically around a rotating motor. If a material with high electrical conductivity is placed near the motor, it is undesirable because it generates a large amount of induced current, which causes resistance to the motor's rotation and causes heat generation. For this reason, it is preferable for the material that makes up the motor to have low electrical conductivity.

[0006] The powder magnetic cores described in Patent Documents 1 and 2 have low thermal conductivity and are therefore unsuitable for applications other than motor cores. In one aspect of the present disclosure, it is preferable to provide a composite material with high thermal conductivity and low electrical conductivity. [Means for solving the problem]

[0007] One aspect of the present disclosure is a composite material including dispersed materials having a thermal conductivity of 100 W / K m or more and an insulator interposed between the dispersed materials. The composite material according to one aspect of the present disclosure has high thermal conductivity and low electrical conductivity. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an explanatory diagram showing the structure of a composite material and a manufacturing method thereof. [Figure 2] FIG. 1 is a perspective view showing the configuration of an apparatus for heating and compressing raw materials. [Figure 3] FIG. 2 is a side cross-sectional view showing the configuration of the device when heat compression is being performed. DETAILED DESCRIPTION OF THE INVENTION

[0009] Exemplary embodiments of the present disclosure will now be described with reference to the drawings. First Embodiment 1. Composition of composite material 1 As shown in S_C in FIG. 1, the composite material 1 includes dispersed materials 3 and insulators 5. The insulators 5 are interposed between the dispersed materials 3. The thermal conductivity of the dispersed materials 3 is 100 W / K·m or more.

[0010] The dispersed material 3 is, for example, a metal powder. Examples of metals include aluminum, copper, silver, gold, and alloys of two or more of these. The dispersed material 3 is, for example, an aluminum-based metal powder. Examples of aluminum-based metal powder include aluminum atomized powder and aluminum cutting chips. The average particle size of the dispersed material 3 is preferably 10 μm or more and 500 μm or less. The average particle size is measured by a mesh passing method.

[0011] The insulator 5 is, for example, a low-melting ceramic, an oxide, a silicone, or a resin. The glass transition point of the insulator 5 is, for example, lower than the melting point of the dispersed material 3. The insulator 5 is, for example, a low-melting ceramic, an oxide, a silicone, or a resin whose glass transition point is lower than the melting point of the dispersed material 3.

[0012] The electrical conductivity of the composite material 1 is, for example, 0.5 × 10 6 S / m or less. One way to reduce the electrical conductivity of the composite material 1 is to increase the amount of insulator 5. The thermal conductivity of the 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 the composite material 1 is to reduce the amount of insulator 5.

[0013] The density of the composite material 1 is, for example, 2.7 g / cm 3 The methods for reducing the density of the composite material 1 include reducing the pressure used when producing the composite material 1 and increasing the diameter of the dispersed materials 3.

[0014] When the mass of the dispersed material 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 dispersed material 3 to the insulator 5 is within this range, the shape of the composite material 1 is likely to be stable. The composite material 1 can be used, for example, as a material for structural components of mobility motors. Examples of structural components include the cover for the entire motor, the fixing plate for the stator, and the fixing plate for the rotor.

[0015] 2. Manufacturing method of composite material 1 The composite material 1 can be manufactured, for example, by the following method. First, a raw material 21 shown as S_A in FIG. 1 is prepared. The raw material 21 includes a dispersion material 3 and an insulator powder 4. When later melted, the insulator powder 4 becomes an insulator 5. The insulator powder 4 functions as a binder. The insulator 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 insulator powder 4 is lower than the melting point of the dispersion material 3. The average particle size of the insulator powder 4 is, for example, 1 μm or more and 30 μm or less.

[0016] The raw material 21 is in the form of, for example, powder. For example, the raw material 21 can be prepared by mixing the dispersing material 3 and the insulating powder 4. For example, a mortar or the like can be used for mixing. For example, in the raw material 21, the dispersing material 3 and the insulating powder 4 are uniformly dispersed.

[0017] Next, the raw material 21 is heated and compressed. When the raw material 21 is heated and compressed, the insulator powder 4 melts and becomes a liquid insulator 5, as shown by S_B and S_C in FIG. 1. When the raw material 21 is heated and compressed, for example, the dispersed material 3 does not melt. The liquid insulator 5 fills the spaces between the dispersed material 3.

[0018] 2 and 3 and a hot press device (not shown) are used as a method for heating and compressing raw material 21. Apparatus 11 includes a cylindrical die 13, a first cylindrical bunch 15, a second cylindrical bunch 17, and a third cylindrical bunch 19.

[0019] The cylindrical die 13 is a hollow cylindrical member. The cylindrical die 13 is composed of an inner peripheral portion 13A and an outer peripheral portion 13B. The outer peripheral portion 13B is located on the outer peripheral side of the inner peripheral portion 13A. The inner peripheral portion 13A is made of graphite. The outer peripheral portion 13B is made of SKD61 steel.

[0020] The first cylindrical bunch 15, the second cylindrical bunch 17, and the third cylindrical bunch 19 are each a member having a cylindrical shape. The diameter D of the first cylindrical bunch 15, the second cylindrical bunch 17, and the third cylindrical bunch 19 is close to, but 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.

[0021] The method for heating and compressing the raw material 21 using the apparatus 11 and the hot press device is as follows. First, as shown in FIG. 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.

[0022] Next, the raw material 21 is placed on the first cylindrical bunch 15. Next, the second cylindrical bunch 17 is placed on the raw material 21. The thickness direction of the second cylindrical bunch 17 coincides with the vertical direction. The raw material 21 is sandwiched between the first cylindrical bunch 15 and the second cylindrical bunch 17 in the vertical direction. In addition, the outer periphery of the raw material 21 faces the inner periphery 13A.

[0023] 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 first cylindrical bunch 15, the raw material 21, and the second cylindrical bunch 17 are entirely contained inside the cylindrical die 13. A lower part of the third cylindrical bunch 19 is contained inside the cylindrical die 13, and the other part protrudes above the cylindrical die 13.

[0024] Next, the device 11 is placed in a hot press. By heating the device 11 while pressing the third cylindrical bunch 19 downward using the hot press, the raw material 21 can be heated and compressed. The heating and compression may be performed under vacuum or atmospheric pressure. When the raw material 21 is heated and compressed, the insulator powder 4 melts and becomes a liquid insulator 5, as shown by S_B and S_C in FIG. 1. When the raw material 21 is heated and compressed, the dispersed material 3 does not melt. The liquid insulator 5 fills the spaces between the dispersed material 3.

[0025] Next, the device 11 is cooled. At this time, the insulator 5 solidifies, and the composite material 1 is completed. The cooling may be performed under vacuum or atmospheric pressure. For example, the cooling may be performed by natural cooling. Next, the device 11 is removed from the hot press device, and then the composite material 1 is removed from the device 11. Through the above steps, the composite material 1 shown in S_C in FIG. 1 is obtained.

[0026] 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, induced current is unlikely to occur in composite material 1, even when composite material 1 is installed in a location where magnetic flux changes drastically, such as around a rotating motor. Because induced current is unlikely to occur in composite material 1, energy loss can be suppressed.

[0027] (1B) For example, the density of the composite material 1 can be reduced. When the density of the composite material 1 is low, the composite material 1 can be used for a mobile object. Examples of mobile objects include HAPS (Flying Aerial Platforms), eVTOL (Electric Vehicles), electric vehicles, drones, etc.

[0028] <Example> 1. Preparation of samples S1 to S7 Samples S1 to S7 were each produced as follows. First, raw material 21 was prepared. In the case of sample S1, raw material 21 consisted of only aluminum powder. In the cases of samples S2 to S6, raw material 21 was a mixture of aluminum powder and low-melting-point ceramic powder. In the cases of samples S2 to S6, the mass ratio of aluminum powder to low-melting-point ceramic powder was as shown in Table 1.

[0029] [Table 1]

[0030] For samples S2 to S6, aluminum powder and low-melting-point ceramic powder were mixed in a mortar for about 5 minutes to prepare raw material 21. By mixing, the low-melting-point ceramic powder was thoroughly coated on the surface of the aluminum powder. After mixing, raw material 21 had no separation between the silver color of the aluminum powder and the white color of the low-melting-point ceramic powder, 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, raw material 21 consisted only of low-melting-point ceramic powder. The purity of the aluminum powder contained in 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 dispersion material 3.

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

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

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

[0035] Next, the device 11 inside the vacuum hot press 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 device 11 was taken out into the atmosphere, and samples S1 to S7 were then taken out of the device 11. Through the above steps, samples S1 to S7 were obtained.

[0036] In the case of sample S1, after compaction, it easily crumbled when removed from apparatus 11. Note that compaction refers to heating and compression followed by cooling. In the cases of samples S2 to S3, the compacts after compaction crumbled and lost their shape. In the cases of samples S4 to S6, the compacts after compaction maintained their shape without crumbling. Samples S4 to S6 correspond to composite material 1. In the case of sample S7, it broke into pieces when removed from apparatus 11, and so a compact could not be obtained.

[0037] 2. Preparation of Samples S8 to S9 The A1050 rolled plate was used as sample S8, and the acrylic plate was used as sample S9.

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

[0039] The density was measured as follows: The mass of the sample was measured using an electronic balance. The diameter and thickness of the sample were measured using 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] Electrical conductivity was measured using a conductivity meter (Sigma Test) manufactured by Nippon Foerster. The measurement frequency was 480 kHz. The size of the test piece used for the measurement was φ25 mm × t1.5 mm. Thermal conductivity was measured using the laser flash method.

[0041] As shown in Table 1, samples S4 to S6 had low density, low electrical conductivity, and high thermal conductivity. The electrical conductivity of samples S4 to S6 was below the measurement limit of 0.5 × 10 6 The electrical conductivity was below S / M. The reason why samples S4 to S6 had low electrical conductivity is presumed to be because ceramic was present between the aluminum particles that make up the aluminum powder, insulating them from each other.

[0042] The electrical conductivity of the parts of samples S1 to S3 that barely retained their shape was measured and found to be 0.5 × 10 6 The S / M ratio was higher than that. The reason for this is presumably that the ceramic did not spread sufficiently between the aluminum particles, resulting in insufficient insulation. Sample S8 had high electrical conductivity. Sample S9 had low thermal conductivity.

[0043] <Other embodiments> Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be implemented in various modified forms.

[0044] (1) The insulating powder 4 contained in the raw material 21 may be in the form of a bamboo blind or a nonwoven fabric. (2) The function of one component in each of the above embodiments may be shared among multiple components, or the functions of multiple components may be performed by one component. Also, part of the configuration of each of the above embodiments may be omitted. Furthermore, at least part of the configuration of each of the above embodiments may be added to or substituted for the configuration of another of the 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 including the composite material 1 as a component, a method for manufacturing the composite material 1, etc. [Explanation of symbols]

[0046] 1...composite material, 3...dispersion material, 4...insulator powder, 5...insulator, 11...device, 13...cylindrical die, 13A...inner peripheral portion, 13B...outer peripheral portion, 15...first cylindrical bunch, 17...second cylindrical bunch, 19...third cylindrical bunch, 21...raw material

[0047] [Technical idea disclosed in this specification] [Item 1] A dispersion material with a thermal conductivity of 100 W / K·m or more; an insulator interposed between the dispersed materials; A composite material comprising: [Item 2] The composite material according to item 1, the insulator is an oxide or resin having a glass transition point lower than the melting point of the dispersion material; Composite material. [Item 3] The composite material according to item 1 or 2, Electrical conductivity is 0.5×10 6 S / m or less, Composite material. [Item 4] The composite material according to any one of items 1 to 3, Thermal conductivity is 8W / K·m or more. Composite material. [Item 5] The composite material according to any one of items 1 to 4, Density is 2.7g / cm 3 Below is the Composite material.

Claims

1. a dispersion material having a thermal conductivity of 100 W / K m or more; an insulator interposed between the dispersed materials; Equipped with The electrical conductivity is 0.5×10 6 S / m or less, The thermal conductivity is 8 W / K m or more, The insulator is a ceramic, an oxide (excluding the ceramic), or a silicone having a glass transition point equal to or lower than the melting point of the dispersed material. Composite material.

2. 2. The composite material according to claim 1, the insulator is the oxide having a glass transition point equal to or lower than the melting point of the dispersion material; Composite material.

3. The composite material according to claim 1 or 2, Density is 2.7 g / cm ３ Below is the Composite material.

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