A high-modulus, high-thermal-conductivity aluminum-based composite material and its preparation method

Abstract

This invention provides a high-modulus, high-thermal-conductivity aluminum-based composite material and its preparation method. The aluminum-based composite material comprises an aluminum matrix and a reinforcing phase. The reinforcing phase includes core-shell structured CNTs@Al3BC particles and in-situ generated nano-reinforcing particles. The mass percentage of externally added CNTs in the composite material is 0.5-3.0%, and the core-shell structured CNTs@Al3BC particles are uniformly distributed between the aluminum matrix grains. The in-situ generated nano-reinforcing particles are γ-Al2O3 and / or AlN. The in-situ generated nano-reinforcing particles are distributed along the grain boundaries of the aluminum matrix grains, and the mass percentage of the in-situ generated nano-reinforcing particles is 2.9-16.4%. This invention also provides a method for preparing the above-mentioned composite material. The composite material of this invention has high modulus and high thermal conductivity, with an elastic modulus reaching 95-120 GPa and a thermal conductivity reaching 150-180 W / m. ‑1 K ‑1 .

Description

Technical Field

[0001] This invention belongs to the field of metal matrix composite technology, specifically relating to a high-modulus, high-thermal-conductivity aluminum matrix composite material and its preparation method. Background Technology

[0002] Aluminum alloys possess excellent mechanical and thermophysical properties, including low density, corrosion resistance, and high specific strength, making them a crucial basic material in the manufacturing industry. Aluminum's density is only one-third that of steel, yet its thermal conductivity is three times that of iron. However, traditional aluminum alloys have a relatively low elastic modulus (stiffness), only around 70 GPa, significantly limiting their application in the automotive, electronics and communications, and defense industries. Furthermore, with increasing demands for energy conservation, emission reduction, and lightweighting, structural components such as heat sinks are trending towards miniaturization and weight reduction, and the increasing power density is leading to ever-increasing requirements for thermal conductivity. However, the thermal conductivity of conventional aluminum alloys cannot meet the ever-increasing demands for heat dissipation performance. Therefore, researching and developing high-modulus, high-thermal-conductivity aluminum-based composite materials has significant application prospects and practical implications.

[0003] To improve the elastic modulus of aluminum alloys, current research both domestically and internationally can be summarized in two directions: alloying and the development of particle-reinforced aluminum matrix composites. Among alloying elements, Li is the most effective in improving the elastic modulus of aluminum alloys; however, Al-Li alloys suffer from demanding surface processing conditions, poor weldability, and their elastic modulus is generally not higher than 92 GPa. Since reinforcing particles (such as SiC, TiC, TiB2, etc.) have high elastic moduli, introducing reinforcing particles into the aluminum matrix to develop aluminum matrix composites is an effective strategy for improving the rigidity of aluminum alloys. Among these, carbon nanotubes (CNTs) are particularly valuable due to their extremely high theoretical elastic modulus (approximately 1 TPa) and excellent thermal conductivity (300-3000 W / m²). -1 K -1 CNTs (Cellular Tissue Materials) are promising reinforcements for aluminum matrix composites. However, the interfacial bond strength between CNTs and the aluminum matrix is ​​weak. When external loads are applied to CNTs-Al composites, the CNTs / Al interface often debonds, failing to effectively transfer the load and making the material highly susceptible to fracture. To address this issue, several studies have proposed methods to in-situ transform the outer layer of CNTs into phases such as Al4C3 to improve interfacial bonding. However, Al4C3 particles are prone to hydrolysis and are highly brittle, significantly affecting the mechanical properties of the composite material.

[0004] Therefore, developing a simple in-situ generation method for preparing carbon nanotube (CNT)-reinforced high-modulus, high-thermal-conductivity aluminum-based composite materials is of great significance. This invention is proposed to this end. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a high-modulus, high-thermal-conductivity aluminum-based composite material and its preparation method. This invention utilizes the liquid-solid reaction of Al with boronite (B₂O₃ or / and BN) to, on the one hand, generate in-situ nanoparticles (γ-Al₂O₃ or / and AlN) distributed in a network along grain boundaries, effectively contributing to the material's stiffness and strength. On the other hand, it enables Al and B elements to undergo a limited interfacial reaction with CNTs to generate Al₃BC. This fully utilizes the contribution of CNTs to the material's thermal conductivity while avoiding the drawback of CNTs' weak interfacial bonding strength with the Al matrix, which leads to easy material damage. Thus, a high-modulus, high-thermal-conductivity aluminum-based composite material is prepared.

[0006] This invention is achieved through the following means:

[0007] A high-modulus, high-thermal-conductivity aluminum-based composite material is disclosed. The composite material comprises an aluminum matrix and a reinforcing phase. The reinforcing phase includes core-shell structured CNTs@Al3BC particles and in-situ generated nano-reinforcing particles. The core-shell structured CNTs@Al3BC particles have an externally added CNT core and an in-situ generated Al3BC particle shell, exhibiting an Al3BC-coated CNT structure. The mass percentage of externally added CNTs in the composite material is 0.5%–3.0%, and the core-shell structured CNTs@Al3BC particles are uniformly distributed between the aluminum matrix grains. The in-situ generated nano-reinforcing particles are γ-Al2O3 and / or AlN. The in-situ generated nano-reinforcing particles are distributed along the grain boundaries of the aluminum matrix grains, and the mass percentage of the in-situ generated nano-reinforcing particles is 2.9%–16.4%.

[0008] According to a preferred embodiment of the present invention, the size of the aluminum matrix grains is 0.2~1.5μm.

[0009] According to a preferred embodiment of the present invention, the added CNTs are multi-walled CNTs with a diameter of 30~100nm, more preferably 30~50nm, and a length of 10~50μm, more preferably 10~20μm; the multi-walled carbon nanotubes are commercially available products.

[0010] According to a preferred embodiment of the present invention, the size of the in-situ generated Al3BC particles is 0.1~1μm.

[0011] According to a preferred embodiment of the present invention, the size of the in-situ generated nano-reinforcing particles is 5~100 nm.

[0012] The preparation method of the above-mentioned high-modulus and high-thermal-conductivity composite material includes the following steps:

[0013] (1) Prepare the required raw materials according to the following mass percentages: aluminum powder 86.7~97.4%, boronite 2.0~10.0%, CNT powder 0.5~3.0%, catalyst 0.1~0.3%;

[0014] (2) Mix the aluminum powder, boronite, CNT powder and catalyst in step (1), and ball mill the resulting material under an argon atmosphere to obtain a mixture.

[0015] (3) Degas the mixture obtained in step (2) and press it into a preform in a cold isostatic press;

[0016] (4) The preform is placed in a heating furnace for heat preservation treatment, and then extruded using a hot extruder to obtain a high modulus and high thermal conductivity aluminum-based composite material.

[0017] According to a preferred embodiment of the present invention, the aluminum powder size in step (1) is ≤80μm, and more preferably 1~50μm.

[0018] According to a preferred embodiment of the present invention, the boron body in step (1) is B2O3 and / or BN, and the size of the boron body is ≤10μm, more preferably 1~5μm.

[0019] According to a preferred embodiment of the present invention, the diameter of the CNTs powder in step (1) is 30~100nm, more preferably 30~50nm, and the length is 10~50μm, more preferably 10~20μm; the CNTs powder is multi-walled carbon nanotube powder.

[0020] According to a preferred embodiment of the present invention, the catalyst in step (1) is graphene oxide, which can be commercially available or prepared by existing methods.

[0021] According to a preferred embodiment of the present invention, the rotation speed of the ball mill in step (2) is ≥300 r / min, more preferably 300~400 r / min; the ball milling time is 1~5 h, and the ball-to-material ratio is 5~12:1.

[0022] According to a preferred embodiment of the present invention, in step (3), the pressure of the cold isostatic press is 210~300MPa.

[0023] According to a preferred embodiment of the present invention, the temperature of the heat preservation treatment in step (4) is 580~800℃, and the heat preservation treatment time is 0.5~4h.

[0024] According to a preferred embodiment of the present invention, the extrusion ratio of the extruder in step (4) is 5 to 25:1.

[0025] The technical features and beneficial effects of this invention are as follows:

[0026] 1. In the aluminum-based composite material of this invention, γ-Al2O3, AlN, and Al3BC particles are spontaneously generated in situ, with clean and uncontaminated surfaces, exhibiting high interfacial bonding strength with the aluminum matrix. γ-Al2O3 and / or AlN nanoparticles exhibit a three-dimensional network distribution along the grain boundaries of the matrix, fully leveraging their configurational strengthening effect to enhance material strength and modulus. High-modulus, high-thermal-conductivity CNTs form CNTs@Al3BC core-shell composite particles in situ, dispersed between grains, effectively enhancing material stiffness and thermal conductivity, and achieving strong bonding with the aluminum matrix, preventing the formation of the brittle Al4C3 phase. Based on the synergistic composite strengthening of these phases with different distributions, sizes, and structures, the composite material can achieve an elastic modulus of 95~120 GPa and a thermal conductivity of 150~180 Wm. -1 K -1 .

[0027] 2. A specific amount of catalyst is added to the aluminum-based composite material of this invention. The catalyst can lower the reaction temperature, regulate the reaction process, and prevent Al3BC particles from growing into undesirable morphologies such as needles. Furthermore, due to the low density of γ-Al2O3, AlN, Al3BC, and CNTs, the composite material prepared by this method has a density ≤3.0 g / cm³. 3 It has a significant lightweight characteristic.

[0028] 3. The method of the present invention is simple. By changing the ratio of aluminum powder, boronite and CNT powder, the mass percentage and distribution characteristics of the reinforcing particles can be controlled. By changing the heat preservation temperature and time, the size of γ-Al2O3 or / and AlN particles, as well as the size of each part of the CNTs@Al3BC core-shell structure, can be controlled, thereby customizing the elastic modulus and thermal conductivity of the composite material according to the application requirements. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the microstructure of the high modulus and high thermal conductivity aluminum matrix composite material of the present invention; in the figure, 1 is the aluminum matrix grain, 2 is the nano-reinforcing particles distributed along the grain boundaries, 3 is the in-situ endogenous Al3BC coating layer, and 4 is the CNTs reinforcing phase.

[0030] Figure 2 The image shows a transmission electron microscope (TEM) image of the microstructure of the high-modulus, high-thermal-conductivity aluminum-based composite material prepared in Example 1; in the image, 1 represents nano-γ-Al2O3 particles, 2 represents CNTs, 3 represents Al3BC, and 4 represents the aluminum matrix.

[0031] Figure 3 The image shows a high-resolution transmission electron microscope (TEM) image of CNTs@Al3BC core-shell structured particles in the high-modulus, high-thermal-conductivity aluminum-based composite material prepared in Example 1; 1 in the image shows the Al3BC particle lattice fringes, and 2 shows the CNTs lattice fringes. Detailed Implementation

[0032] The present invention will be further described below with reference to specific embodiments, but is not limited thereto.

[0033] Furthermore, unless otherwise specified, the experimental methods described in the following embodiments are all conventional methods; and unless otherwise specified, the reagents, materials and equipment are all commercially available.

[0034] The purity of the aluminum powder, boronite, and multi-walled CNTs powder used in the examples was 99.9%. Example 1

[0035] A method for preparing a high-modulus, high-thermal-conductivity aluminum-based composite material includes the following steps:

[0036] (1) Prepare the required raw materials according to the following mass percentages: 92.3% spherical aluminum powder (size 1μm), 5.0% boronite (B2O3 powder) (size 1μm), 2.5% CNTs powder (multi-walled, diameter 30nm, length 10μm), and 0.2% catalyst (graphene oxide);

[0037] (2) Mix the spherical aluminum powder, boronite, CNT powder and catalyst in step (1), and ball mill the resulting material at high speed (360 r / min) for 2 h in an argon atmosphere. The ball-to-material ratio is set at 7:1 to obtain the mixture.

[0038] (3) The mixture obtained in step (2) is degassed and pressed into a preform in a cold isostatic press at a pressure of 210 MPa;

[0039] (4) The preform is placed in a heating furnace and kept at 700℃ for 1 hour. It is then extruded using a hot extruder with an extrusion ratio of 16:1 to obtain a high-modulus, high-thermal-conductivity aluminum-based composite material.

[0040] This embodiment yields a high-modulus, high-thermal-conductivity aluminum matrix composite material reinforced with γ-Al2O3 and CNTs@Al3BC core-shell particles. The γ-Al2O3 particles have a size of approximately 20 nm and a mass fraction of 7.3%, distributed along the grain boundaries of the aluminum matrix. Al3BC particles, approximately 500 nm in size, are formed in situ around the CNT particles. The resulting core-shell structure of CNTs@Al3BC particles is diffusely distributed between the aluminum matrix grains. Transmission electron microscopy (TEM) images are shown below. Figure 2 As shown, high-resolution transmission electron microscopy images of CNTs@Al3BC core-shell structured particles in the composite material are as follows: Figure 3 As shown; the composite material has an elastic modulus of 98 GPa and a thermal conductivity of 162 W / m². -1 K -1 . Example 2

[0041] A method for preparing a high-modulus, high-thermal-conductivity aluminum-based composite material includes the following steps:

[0042] (1) Prepare the required raw materials according to the following mass percentages: 94.7% spherical aluminum powder (size 20μm), 2.0% boronite (BN powder) (size 5μm), 3.0% CNTs powder (multi-walled, diameter 50nm, length 20μm), and 0.3% catalyst (graphene oxide);

[0043] (2) Mix the high-purity spherical aluminum powder, boronite, CNT powder and catalyst in step (1), and ball mill the resulting material at high speed (300 r / min) for 5 h in an argon atmosphere. The ball-to-material ratio is set at 5:1 to obtain the mixture.

[0044] (3) The mixture obtained in step (2) is degassed and pressed into a preform in a cold isostatic press at a pressure of 300 MPa;

[0045] (4) The preform is placed in a heating furnace and kept at 800℃ for 0.5h. It is then extruded using a hot extruder with an extrusion ratio of 5:1 to obtain a high-modulus, high-thermal-conductivity aluminum-based composite material.

[0046] This embodiment yields a high-modulus, high-thermal-conductivity aluminum matrix composite material reinforced with AlN and CNT@Al3BC core-shell particles. The AlN particles have a size of 80 nm and a mass fraction of 3.3%, distributed along the grain boundaries of the aluminum matrix. Al3BC particles with a size of 1 μm are formed in situ around the CNT particles, and the resulting core-shell structure of CNTs@Al3BC particles is dispersed between the aluminum matrix grains. The composite material has an elastic modulus of 105 GPa and a thermal conductivity of 171 W / m². -1 K -1 . Example 3

[0047] A method for preparing a high-modulus, high-thermal-conductivity aluminum-based composite material includes the following steps:

[0048] (1) Prepare the required raw materials according to the following mass percentages: 89.4% spherical aluminum powder (size 50μm), 10.0% boronite (equal mass mixture of B2O3 and BN powder) (size 2μm), 0.5% CNT powder (multi-walled, diameter 40nm, length 15μm), and 0.1% catalyst (graphene oxide);

[0049] (2) Mix the high-purity spherical aluminum powder, boronite, CNT powder and catalyst in step (1), and ball mill the resulting material at high speed (400 r / min) for 1 h in an argon atmosphere. The ball-to-material ratio is set at 10:1 to obtain the mixture.

[0050] (3) The mixture obtained in step (2) is degassed and pressed into a preform in a cold isostatic press at a pressure of 250 MPa;

[0051] (4) The preform is placed in a heating furnace and kept at 600℃ for 3 hours. It is then extruded using a hot extruder with an extrusion ratio of 20:1 to obtain a high-modulus, high-thermal-conductivity aluminum-based composite material.

[0052] This embodiment yields a high-modulus, high-thermal-conductivity aluminum-based composite material reinforced with γ-Al₂O₃, AlN, and CNTs@Al₃BC core-shell particles. The γ-Al₂O₃ particles have a size of approximately 10 nm and a mass fraction of 7.3%, while the AlN particles have a size of 30 nm and a mass fraction of 8.2%. Both types of particles are distributed along the grain boundaries of the aluminum matrix. Al₃BC particles with a size of 200 nm are formed in situ around the CNT particles, and the resulting core-shell CNT@Al₃BC particles are dispersed between the aluminum matrix grains. The composite material has an elastic modulus of 115 GPa and a thermal conductivity of 156 W / m². -1 K -1 .

Claims

1. A high-modulus, high-thermal-conductivity aluminum-based composite material, characterized in that, This aluminum-based composite material comprises an aluminum matrix and a reinforcing phase. The reinforcing phase includes core-shell structured CNTs@Al3BC particles and in-situ generated nano-reinforcing particles. The core-shell structured CNTs@Al3BC particles have an added CNT core and an in-situ generated Al3BC particle shell, exhibiting an Al3BC-coated CNT structure. The added CNTs in the composite material have a mass percentage of 0.5% to 3.0%, and the core-shell structured CNTs@Al3BC particles are uniformly distributed between the aluminum matrix grains. The in-situ generated nano-reinforcing particles are γ-Al2O3 and / or AlN. The in-situ generated nano-reinforcing particles are distributed along the grain boundaries of the aluminum matrix, and the mass percentage of the in-situ generated nano-reinforcing particles is 2.9% to 16.4%. The size of the aluminum matrix grains is 0.2~1.5μm; the added CNTs are multi-walled CNTs with a diameter of 30~100nm and a length of 10~50μm; the size of the in-situ generated Al3BC particles is 0.1~1μm; and the size of the in-situ generated nano-reinforcing particles is 5~100nm.

2. The high-modulus, high-thermal-conductivity aluminum-based composite material according to claim 1, characterized in that, The added CNTs have a diameter of 30~50nm and a length of 10~20μm.

3. A method for preparing the high-modulus, high-thermal-conductivity aluminum-based composite material according to any one of claims 1-2, comprising the following steps: (1) Prepare the required raw materials according to the following mass percentages: aluminum powder 86.7~97.4%, boronite 2.0~10.0%, CNT powder 0.5~3.0%, catalyst 0.1~0.3%; (2) Mix the aluminum powder, boronite, CNT powder and catalyst in step (1), and ball mill the resulting material under an argon atmosphere to obtain a mixture. (3) Degas the mixture obtained in step (2) and press it into a preform in a cold isostatic press; (4) The preform is placed in a heating furnace for heat preservation treatment, and then extruded using a hot extruder to obtain a high modulus and high thermal conductivity aluminum-based composite material.

4. The method for preparing the high-modulus, high-thermal-conductivity aluminum-based composite material according to claim 3, characterized in that, The aluminum powder size in step (1) is ≤80μm.

5. The method for preparing the high-modulus, high-thermal-conductivity aluminum-based composite material according to claim 3, characterized in that, The aluminum powder in step (1) has a size of 1~50μm.

6. The method for preparing the high-modulus, high-thermal-conductivity aluminum-based composite material according to claim 3, characterized in that, The boron body mentioned in step (1) is B2O3 and / or BN, and the size of the boron body is ≤10μm.

7. The method for preparing the high-modulus, high-thermal-conductivity aluminum-based composite material according to claim 3, characterized in that, The size of the boron body mentioned in step (1) is 1~5 μm.

8. The method for preparing the high-modulus, high-thermal-conductivity aluminum-based composite material according to claim 3, characterized in that, The CNTs powder mentioned in step (1) has a diameter of 30~100nm and a length of 10~50μm; the CNTs powder is multi-walled carbon nanotube powder.

9. The method for preparing the high-modulus, high-thermal-conductivity aluminum-based composite material according to claim 3, characterized in that, The CNT powder in step (1) has a diameter of 30~50nm and a length of 10~20μm.

10. The method for preparing the high-modulus, high-thermal-conductivity aluminum-based composite material according to claim 3, characterized in that, The ball milling speed in step (2) is ≥300 r / min; the ball milling time is 1~5 h, and the ball-to-material ratio is 5~12:

1.

11. The method for preparing the high-modulus, high-thermal-conductivity aluminum-based composite material according to claim 3, characterized in that, The ball milling speed in step (2) is 300~400 r / min.

12. The method for preparing the high-modulus, high-thermal-conductivity aluminum-based composite material according to claim 3, characterized in that, In step (3), the pressure of the cold isostatic press is 210~300MPa.

13. The method for preparing the high-modulus, high-thermal-conductivity aluminum-based composite material according to claim 3, characterized in that, The temperature of the heat preservation treatment in step (4) is 580~800℃, and the heat preservation time is 0.5~4h; the extrusion ratio of the extruder is 5~25:1.

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