Radial graphite flake-copper-based composite material and method for manufacturing the same

Abstract

This invention relates to a radial graphite flake-copper-based composite material and its preparation method. The preparation method includes the following steps: S1, graphite flake pretreatment; S2, depositing a metal layer on the surface of the graphite flakes; S3, thoroughly mixing graphite flakes with different volume fractions of metal-coated layers and copper powder, followed by heating and pressurizing sintering; S4, cutting the sintered sample into several triangular prisms in the X-Y plane, arranging the cut prisms into cylinders with the central angle as the vertex, so that the graphite flakes are arranged radially and vertically outward with the Z-axis as the center, filling the gaps in the prisms with copper powder, and then heating and pressurizing to sinter to obtain the radial graphite flake-copper-based composite material. This invention adjusts the orientation of the graphite flakes to the Z-plane direction through cutting and reorganization, significantly improving the thermal conductivity in the Z-plane direction while maintaining the thermal conductivity in the XY plane.

Description

Technical Field

[0001] This invention belongs to the field of preparation technology of thermally isotropic graphite-copper composite materials, specifically relating to a radial graphite flake-copper-based composite material and its preparation method. Background Technology

[0002] Graphite possesses high thermal conductivity in the XY directions (1200 W / mK), and copper is also a readily available metal with high thermal conductivity (400 W / mK), making graphite / copper composites a subject of extensive research in thermal management. However, due to the two-dimensional nature of graphite, its thermal conductivity in the Z-axis direction is low (10-20 W / mK), resulting in low thermal conductivity (<100 W / mK) in the Z-axis direction for graphite / copper composites. This anisotropic difference limits the application of graphite / copper composites in thermal management. Therefore, it is necessary to investigate a method to further improve the thermal conductivity in the Z-axis direction while maintaining the high in-plane thermal conductivity of graphite / copper composites.

[0003] Chinese invention patent application CN201810677269.1 discloses a method for preparing a copper-based composite material reinforced with high thermal conductivity isotropic graphite spheres, comprising pure copper powder and graphite spheres. The prepared graphite sphere-copper-based composite material exhibits approximately isotropic thermal conductivity and uniform microstructure distribution. However, the isotropic nature of the graphite spheres used in this invention reduces the overall thermal conductivity to around 70 W / mK, which falls short of the ideal value. Chinese invention patent application CN202110777824.X discloses a sandwich-structured graphite-copper-graphite heat dissipation film and its preparation method, comprising a copper layer and graphite layers located on both sides of the copper layer; a metal or non-metal transition layer is present between the copper layer and the graphite layer. The method for preparing this sandwich-structured graphite-copper-graphite heat dissipation film results in a heat dissipation film with strong interfacial bonding and low interfacial thermal resistance. However, the longitudinal thermal conductivity of this invention does not reach the ideal value and cannot solve the problem of localized high heat dissipation in current electronic devices. Summary of the Invention

[0004] In summary, the purpose of this invention is to provide a composite material in which the orientation of all graphite flakes is adjusted to be vertical and the overall configuration of the graphite flakes is radial. This fully utilizes the advantage of high in-plane thermal conductivity, and improves the thermal conductivity in the Z-axis direction without reducing the thermal conductivity in the XY plane. Furthermore, it is designed to solve the problem of high local heat. By arranging the positions of the reinforcing terms and placing more graphite flakes in the high-heat area, the local heat dissipation value can be improved, thus solving the problem of low out-of-plane thermal conductivity of graphite / copper composite materials mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a radial graphite flake-copper-based composite material, wherein the graphite flakes in the graphite flake-copper-based composite material are arranged vertically in a radial pattern centered on the Z-axis.

[0006] The preparation method of the graphite flake-copper-based composite material includes the following steps: S1, graphite flake pretreatment; S2, coating the graphite flake surface with a metal layer; S3, after thoroughly mixing graphite flakes and copper powder with different volume fractions of metal layer coating, placing them in a cylindrical graphite mold and heating and pressurizing for sintering to obtain graphite flake-copper composite materials with different volume fractions; S4, cutting the sintered sample in step S3 into several triangular prisms in the XY plane with a central angle of 10°-45°, arranging the cut triangular prisms into cylinders with the central angle as the apex, so that the graphite flakes are arranged radially and vertically outward with the Z-axis as the center, filling the gaps in the triangular prisms with copper powder, and heating and pressurizing the cylindrical sample to obtain radial graphite flake-copper-based composite material.

[0007] Furthermore, the graphite flakes have a thickness of 2-30 μm, an aspect ratio of 5-20, and a density of 1.8-2.2 g / cm³. 3 The volume fraction of graphite flakes is 20%-60%.

[0008] Furthermore, step S1, the graphite flake pretreatment, specifically involves degreasing, roughening, and sensitizing the graphite flakes.

[0009] Furthermore, in step S2, the coating on the graphite flake surface can be achieved by chemical plating, electroplating, vacuum vapor deposition, or salt bath plating, with a coating thickness of 0.1-2 micrometers.

[0010] Furthermore, the metal layer plated in step S2 is one of copper, nickel, tungsten, titanium, and zirconium.

[0011] Furthermore, the S3 rapid heating and pressurizing sintering process involves heating to 780-900℃ at a rate of 100℃ / min and holding at 30MPa pressure for 10 minutes.

[0012] Furthermore, the S4 heating and pressurizing sintering process involves heating at a rate of 100℃ / min and holding at 780-900℃ and 20-35MPa for 10 minutes.

[0013] The beneficial effects of this invention are as follows:

[0014] 1. The present invention uses a plating method to plate copper, nickel, tungsten, titanium or zirconium coatings on graphite flakes, which improves the interfacial bonding between graphite flakes and copper, avoids the problem of a significant decrease in heat transfer capacity caused by air gaps, and effectively improves the heat conductivity.

[0015] 2. This invention adjusts the orientation of graphite flakes to the Z-plane direction by cutting and recombining, which significantly improves the thermal conductivity in the Z-plane direction while maintaining the thermal conductivity in the XY plane. Attached Figure Description

[0016] Figure 1 The graphite flakes in the graphite flake-copper matrix composite material prepared for this invention are arranged vertically in a radial pattern centered on the Z-axis.

[0017] Figure 2 This is a schematic diagram of step S4 of the present invention. Detailed Implementation

[0018] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading this invention, any modifications of the invention in various equivalent forms by those skilled in the art will fall short of the scope defined by the appended claims.

[0019] Comparative Example 1

[0020] 1) Select copper powder with a purity of 99.9% and an average particle size of 20 μm, and a thickness of 20 μm and a density of 2.2 g / cm³. 3 Graphite flakes with a volume fraction of 40% were subjected to chemical copper plating, with a coating thickness of 1 μm.

[0021] 2) Copper-plated graphite flakes and copper composite powder are placed in a cylindrical graphite mold and sintered using the SPS process at a vacuum degree of 10. -3 A horizontally aligned graphite flake / copper composite material was prepared by sintering at 850℃ for 10 min under a heating rate of 100℃ / min and a sintering pressure of 30MPa. The thermal conductivity of the composite material in the XY direction reached 470 W·m. -1 ·K -1 The thermal conductivity in the Z direction is 73 W·m. -1 ·K -1 .

[0022] Example 1

[0023] 1) Select copper powder with a purity of 99.9% and an average particle size of 20 μm, and a thickness of 20 μm and a density of 2.2 g / cm³. 3 Graphite flakes with a volume fraction of 40% were subjected to chemical copper plating, with a coating thickness of 1 μm.

[0024] 2) Copper-plated graphite flakes and copper composite powder are placed in a cylindrical graphite mold and sintered using the SPS process at 10°C. -3Horizontally arranged graphite flakes / copper composite material was prepared by sintering at 850℃ for 10 min under a heating rate of 100℃ / min and a sintering pressure of 30MPa.

[0025] 3) Subsequently, a diamond wire cutter was used to cut the sample into a triangular shape in the XY plane. The cut samples were then rearranged and reassembled, the gaps were filled with copper powder, and SPS sintering was performed at 10... -3 Under a heating rate of 100℃ / min and a sintering pressure of 25MPa, a secondary sintering process was performed at 800℃ for 10 min to obtain a radially longitudinally arranged graphite flake / copper composite material. Its thermal conductivity in the XY direction reached 518 W·m. -1 ·K -1 The thermal conductivity in the Z direction can reach 479 W·m. -1 ·K -1 .

[0026] Example 2

[0027] 1) Select copper powder with a purity of 99.9% and an average particle size of 20μm. Select graphite flakes with a thickness of 20μm, a density of 2.2g / cm3, and a volume fraction of 50%. Perform chemical copper plating on the graphite flakes to achieve a coating thickness of 2μm.

[0028] 2) Copper-plated graphite flakes and copper composite powder are placed in a cylindrical graphite mold and sintered using the SPS process at 10°C. -3 Horizontally arranged graphite flakes / copper composite material was prepared by sintering at 850℃ for 10 min under a heating rate of 100℃ / min and a sintering pressure of 30MPa.

[0029] 3) Subsequently, a diamond wire cutter was used to cut the sample into a triangular shape in the XY plane. The cut samples were then rearranged and reassembled, the gaps were filled with copper powder, and SPS sintering was performed at 10... -3 Under a heating rate of 100℃ / min and a sintering pressure of 25MPa, a secondary sintering process was performed at 800℃ for 10 min to obtain a radially longitudinally arranged graphite flake / copper composite material. Its thermal conductivity in the XY direction reached 498 W·m. -1 ·K -1 The thermal conductivity in the Z direction can reach 487 W·m. -1 ·K -1 .

[0030] Example 3

[0031] 1) Select copper powder with a purity of 99.9% and an average particle size of 20μm. Select graphite flakes with a thickness of 20μm, a density of 2.2g / cm3, and a volume fraction of 60%. Perform chemical copper plating on the graphite flakes to achieve a coating thickness of 1μm.

[0032] 2) Copper-plated graphite flakes and copper composite powder are placed in a cylindrical graphite mold and sintered using the SPS process at 10°C. -3 Horizontally arranged graphite flakes / copper composite material was prepared by sintering at 850℃ for 10 min under a heating rate of 100℃ / min and a sintering pressure of 30MPa.

[0033] 3) Subsequently, a diamond wire cutter was used to cut the sample into a triangular shape in the XY plane. The cut samples were then rearranged and reassembled, the gaps were filled with copper powder, and SPS sintering was performed at 10... -3 Under a heating rate of 100℃ / min and a sintering pressure of 25MPa, a secondary sintering process was performed at 800℃ for 10 min to obtain a radially longitudinally arranged graphite flake / copper composite material. Its thermal conductivity in the XY direction reached 482 W·m. -1 ·K -1 The thermal conductivity in the Z direction can reach 474 W·m. -1 ·K -1 .

[0034] Example 4

[0035] 1) Select copper powder with a purity of 99.9% and an average particle size of 20μm. Select graphite flakes with a thickness of 20μm, a density of 2.2g / cm3, and a volume fraction of 40%. Perform chemical tungsten plating on the graphite flakes to achieve a coating thickness of 0.5μm.

[0036] 2) Copper-plated graphite flakes and copper composite powder are placed in a cylindrical graphite mold and sintered using the SPS process at 10°C. -3 Horizontally arranged graphite flakes / copper composite material was prepared by sintering at 850℃ for 10 min under a heating rate of 100℃ / min and a sintering pressure of 30MPa.

[0037] 3) Subsequently, a diamond wire cutter was used to cut the sample into a triangular shape in the XY plane. The cut samples were then rearranged and reassembled, the gaps were filled with copper powder, and SPS sintering was performed at 10... -3 Under a heating rate of 100℃ / min and a sintering pressure of 25MPa, a secondary sintering process was performed at 800℃ for 10 min to obtain a radially longitudinally arranged graphite flake / copper composite material. Its thermal conductivity in the XY direction reached 465 W·m. -1 ·K -1The thermal conductivity in the Z direction can reach 442 W·m. -1 ·K -1 .

[0038] Example 5

[0039] 1) Select copper powder with a purity of 99.9% and an average particle size of 20μm. Select graphite flakes with a thickness of 20μm, a density of 2.2g / cm3, and a volume fraction of 40%. Perform chemical titanium plating on the graphite flakes to achieve a coating thickness of 0.5μm.

[0040] 2) Copper-plated graphite flakes and copper composite powder are placed in a cylindrical graphite mold and sintered using the SPS process at 10°C. -3 Horizontally arranged graphite flakes / copper composite material was prepared by sintering at 850℃ for 10 min under a heating rate of 100℃ / min and a sintering pressure of 30MPa.

[0041] 3) Subsequently, a diamond wire cutter was used to cut the sample into a triangular shape in the XY plane. The cut samples were then rearranged and reassembled, the gaps were filled with copper powder, and SPS sintering was performed at 10... -3 Under a heating rate of 100℃ / min and a sintering pressure of 25MPa, a secondary sintering process was performed at 800℃ for 10 min to obtain a radially longitudinally arranged graphite flake / copper composite material. Its thermal conductivity in the XY direction reached 447 W·m. -1 ·K -1 The thermal conductivity in the Z direction can reach 419 W·m. -1 ·K -1 .

[0042] Example 6

[0043] 1) Select copper powder with a purity of 99.9% and an average particle size of 20μm. Select graphite flakes with a thickness of 20μm, a density of 2.2g / cm3, and a volume fraction of 40%. Perform electroless nickel plating on the graphite flakes, with a plating thickness of 1μm.

[0044] 2) Copper-plated graphite flakes and copper composite powder are placed in a cylindrical graphite mold and sintered using the SPS process at 10°C. -3 Horizontally arranged graphite flakes / copper composite material was prepared by sintering at 850℃ for 10 min under a heating rate of 100℃ / min and a sintering pressure of 30MPa.

[0045] 3) Subsequently, a diamond wire cutter was used to cut the sample into a triangular shape in the XY plane. The cut samples were then rearranged and reassembled, the gaps were filled with copper powder, and SPS sintering was performed at 10... -3Under a heating rate of 100℃ / min and a sintering pressure of 25MPa, a secondary sintering process was performed at 800℃ for 10 min to obtain a radially longitudinally arranged graphite flake / copper composite material. Its thermal conductivity in the XY direction reached 446 W·m. -1 ·K -1 The thermal conductivity in the Z direction can reach 428 W·m. -1 ·K -1 .

[0046] Example 7

[0047] 1) Select copper powder with a purity of 99.9% and an average particle size of 20μm. Select graphite flakes with a thickness of 20μm, a density of 2.2g / cm3, and a volume fraction of 40%. Perform chemical chromium plating on the graphite flakes to achieve a coating thickness of 1μm.

[0048] 2) Copper-plated graphite flakes and copper composite powder are placed in a cylindrical graphite mold and sintered using the SPS process at 10°C. -3 Horizontally arranged graphite flakes / copper composite material was prepared by sintering at 850℃ for 10 min under a heating rate of 100℃ / min and a sintering pressure of 35MPa.

[0049] 3) Subsequently, a diamond wire cutter was used to cut the sample into a triangular shape in the XY plane. The cut samples were then rearranged and reassembled, the gaps were filled with copper powder, and SPS sintering was performed at 10... -3 Under a heating rate of 100℃ / min and a sintering pressure of 25MPa, a secondary sintering process was performed at 800℃ for 10 min to obtain a radially longitudinally arranged graphite flake / copper composite material. Its thermal conductivity in the XY direction reached 466 W·m. -1 ·K -1 The thermal conductivity in the Z direction can reach 439 W·m. -1 ·K -1 .

Claims

1. A radial graphite flake-copper-based composite material, characterized in that, The graphite flakes in the graphite flake-copper-based composite material are arranged vertically in a radial pattern centered on the Z-axis. The preparation method of the graphite flake-copper-based composite material includes the following steps: S1, Pretreatment of graphite flakes, wherein the graphite flakes have a thickness of 2-30 μm, an aspect ratio of 5-20, and a density of 1.8-2.2 g / cm³. 3 The volume fraction of graphite flakes is 20%-60%; S2, a metal layer is deposited on the surface of graphite flakes, and the deposited metal layer is one of copper, nickel, tungsten, titanium, and zirconium; S3. After thoroughly mixing graphite flakes and copper powder with different volume fractions of metal coating, the mixture is placed in a cylindrical graphite mold and heated and sintered under pressure to obtain graphite flake copper composite materials with different volume fractions. S4. Cut the sintered sample from step S3 into several triangular prisms in the XY plane with a central angle of 10°-45°. Arrange the cut triangular prisms into cylinders. Fill the gaps between the triangular prisms with copper powder. Heat and pressurize the cylindrical sample to obtain a radial graphite flake-copper-based composite material.

2. The radial graphite flake-copper-based composite material as described in claim 1, characterized in that, The graphite flake pretreatment step S1 specifically involves degreasing, roughening, and sensitizing the graphite flakes.

3. The radial graphite flake-copper-based composite material as described in claim 1, characterized in that, In step S2, the graphite flakes can be coated using chemical plating, electroplating, vacuum vapor deposition, or salt bath plating, with a coating thickness of 0.1-2 micrometers.

4. The radial graphite flake-copper-based composite material as described in claim 1, characterized in that, The S3 rapid heating and pressurizing sintering process involves heating to 780-900℃ at a rate of 100℃ / min and holding at 30MPa pressure for 10 minutes.

5. The radial graphite flake-copper-based composite material as described in claim 1, characterized in that, The S4 heating and pressurizing sintering process involves heating at a rate of 100℃ / min and holding at 780-900℃ and 20-35MPa for 10 minutes.

Images