Modified aluminum-based composite material as well as preparation method and application thereof

Abstract

The invention provides a modified aluminum-based composite material and a preparation method and application thereof, and the preparation method creatively adopts an acoustic resonance mixer to perform coating treatment on carbon nanotubes and aluminum-based alloy powder so as to form a continuous and compact carbon nanotube coating layer on the outer surface of the aluminum-based alloy powder. The modified aluminum-based composite material prepared through the method has excellent comprehensive performance of radiation resistance, high heat conductivity and high strength, and has a wider industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of laser additive manufacturing technology for aluminum-based composite materials, and particularly to a modified aluminum-based composite material, its preparation method, and its applications. Background Technology

[0002] Aluminum-based composite materials, with their low density, high specific strength, and excellent thermal and electrical conductivity, have become ideal candidate materials for precision components in aerospace, nuclear industry, and other fields. In particular, their application in the harsh operating environments of deep space exploration and nuclear reactors places even more stringent requirements on them. They not only need to have efficient heat dissipation capabilities to ensure the stable operation of electronic components or core parts, but also need to withstand the material performance degradation caused by high-energy particle radiation.

[0003] Currently, laser powder bed fusion (LPBF) additive manufacturing technology has become the mainstream method for preparing aluminum-based composite components, offering the advantage of high freedom in complex structural design. However, the preparation of carbon nanotube-coated aluminum-based composites using this technology still faces several key technical bottlenecks. First, carbon nanotubes have extremely poor wettability with the aluminum matrix, easily agglomerating during laser melting and solidification, resulting in weak interfacial bonding and ineffective heat and stress transfer, hindering the full realization of their toughening and thermal conductivity enhancement effects. Second, under high-energy laser irradiation, carbon nanotubes readily undergo interfacial reactions with the aluminum matrix to generate the harmful Al4C3 phase, which not only significantly reduces the material's thermal conductivity but also lowers the composite's mechanical properties and radiation resistance stability. Third, conventional carbon nanotube addition methods struggle to achieve uniform dispersion and high-density coating within the aluminum matrix, resulting in limited improvement in the material's radiation resistance and thermal conductivity, failing to meet the requirements of harsh service environments.

[0004] Therefore, existing methods for preparing modified aluminum-based composite materials suffer from problems such as weak coating density between the aluminum matrix and carbon nanotubes, or weak interfacial bonding between carbon nanotubes and the aluminum matrix, or susceptibility to reactions, resulting in poor mechanical properties, thermal conductivity, and radiation resistance of the composite material. There is an urgent need to provide a method for preparing modified aluminum-based composite materials and a modified aluminum-based composite material itself to improve these problems. Summary of the Invention

[0005] The existing methods for preparing modified aluminum-based composite materials suffer from problems such as weak coating density between the aluminum matrix and carbon nanotubes, or weak interfacial bonding between carbon nanotubes and the aluminum matrix, or easy reaction, which result in poor mechanical properties, thermal conductivity, and radiation resistance of the composite materials.

[0006] This invention provides a method for preparing a modified aluminum-based composite material. The method includes: Step S1, coating carbon nanotubes and aluminum-based alloy powder in an acoustic resonance mixer to obtain aluminum-based alloy powder with a carbon nanotube coating layer on the outer surface; Step S2, establishing a three-dimensional solid geometric model using modeling software, and using slicing software to slice the model into layers and plan the laser scanning path to discretize the three-dimensional solid into two-dimensional data; Step S3, according to the two-dimensional data, melting the aluminum-based alloy powder with the carbon nanotube coating layer in a laser powder bed melting device to obtain a shaped aluminum-based composite material; Step S4, subjecting the shaped aluminum-based composite material to aging heat treatment to obtain a modified aluminum-based composite material; wherein, the coating process in the acoustic resonance mixer includes: sequentially performing a mixing program segment-stop program segment-mixing program segment cycle, with 8 to 12 cycles, a mixing program segment time of 20 to 60 seconds, and a stop program segment time of 40 to 120 seconds.

[0007] Furthermore, in step S1, the amount of carbon nanotubes added accounts for 1~3wt% of the modified aluminum-based composite material; preferably, the material is cyclically treated and then cooled, with a cooling temperature of 30~40℃.

[0008] Furthermore, the aluminum-based alloy powder has a particle size D50 of 20~55μm and a purity >99%; preferably, the carbon nanotubes are multi-walled carbon nanotubes with an outer diameter of 11~45nm, a length of 11~55μm, and a purity ≥98%.

[0009] Furthermore, the acoustic resonance mixer has a gravitational acceleration of 0.1~1.0g, a resonance frequency of 45~60Hz, and an operating temperature of 65~70℃; preferably, in step S4, the aging heat treatment is carried out in a muffle furnace.

[0010] Furthermore, in step S3, before the melting treatment, a drying treatment is required, with a treatment temperature of 50~70℃ and a treatment time of 2~6h.

[0011] Furthermore, the starting temperature of the aging heat treatment is 20~40℃, the heating rate is 3~8℃ / min, the holding temperature is 280~370℃, and the holding time is 2~5h.

[0012] In another aspect, the present invention provides a modified aluminum-based composite material, which is obtained by the above-described method for preparing the modified aluminum-based composite material.

[0013] Furthermore, the modified aluminum-based composite material includes an aluminum alloy matrix and a carbon nanotube coating layer on the outer surface of the aluminum alloy matrix. The thickness of the carbon nanotube coating layer is 10~20 nm and the density is 1.2~2.1 g / cm³.

[0014] Furthermore, the modified aluminum-based composite material has a thermal conductivity of 170~190 W / mK and a thermal diffusivity of 45~60 mm. 2 / s.

[0015] In another aspect, the present invention provides a modified aluminum-based composite material for use in aerospace, nuclear industry, or new energy vehicle fields.

[0016] Compared with existing technologies, the advantages of this invention are as follows: Firstly, the uniform coating and good interfacial bonding of carbon nanotubes in the aluminum matrix significantly improves the radiation resistance of the composite material. The interface between the carbon nanotubes and the matrix can adsorb and reduce point defects caused by radiation, inhibit the formation and growth of dislocation loops and void defects, thereby reducing problems such as surface blistering, abnormal increase in hardness, and decrease in elongation under radiation environment, and thus improving its mechanical properties. Secondly, based on the high thermal conductivity of carbon nanotubes, the close bonding with the aluminum-based alloy promotes the rapid transfer of heat energy in the material, giving the composite material good heat dissipation performance. Secondly, the preparation method provided by this invention can achieve uniform dispersion of carbon nanotubes in the aluminum-based alloy, reduce the performance inhomogeneity caused by agglomeration, and ensure the forming integrity of the modified composite material in complex structures, which is conducive to the integrated forming of components. The modified aluminum-based composite material prepared by this invention has superior comprehensive properties of radiation resistance, high thermal conductivity, and high strength, and has a broader prospect for industrial application. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 SEM image (magnification approximately 3000x) of the modified aluminum-based composite material prepared according to Example 1 of the present invention. Figure 2 The image shows a SEM image (magnification approximately 10,000x) of the modified aluminum-based composite material prepared according to Example 1 of the present invention after irradiation. Figure 3 The image shows a SEM image (magnification approximately 10,000x) of the modified aluminum-based composite material prepared according to Example 2 of the present invention after irradiation. Figure 4 The image shows a SEM image (magnification approximately 10,000x) of the modified aluminum-based composite material prepared according to Example 3 of the present invention after irradiation. Figure 5 SEM image (magnification approximately 10,000x) of the modified aluminum-based composite material prepared according to Comparative Example 1 of the present invention after irradiation. Figure 6 The image shows a SEM image (magnification approximately 10,000x) of the modified aluminum-based composite material prepared according to Comparative Example 2 of this invention after irradiation. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0020] According to the existing methods for preparing modified aluminum-based composite materials, there are technical problems such as weak coating density between the aluminum matrix and carbon nanotubes, or weak interfacial bonding force between carbon nanotubes and aluminum matrix, or easy reaction, which leads to poor mechanical properties, thermal conductivity and radiation resistance of the composite material. Based on this, the present invention provides a method for preparing a modified aluminum-based composite material, the method comprising: step S1, taking carbon nanotubes and aluminum-based alloy powder and coating them in an acoustic resonance mixer to obtain aluminum-based alloy powder with a carbon nanotube coating layer on the outer surface; step S2, using modeling software to establish a three-dimensional solid geometric model, and using slicing software to slice the model into layers and plan the laser scanning path to discretize the three-dimensional solid into two-dimensional data; step S3, according to the two-dimensional data, melting the aluminum-based alloy powder with a carbon nanotube coating layer in a laser powder bed melting device to obtain a shaped aluminum-based composite material; step S4, taking the shaped aluminum-based composite material and subjecting it to aging heat treatment to obtain a modified aluminum-based composite material; wherein, the coating process in the acoustic resonance mixer includes: sequentially performing a mixing program segment-stop program segment-mixing program segment cyclic processing, the number of cycles being 8 to 12, the mixing program segment time being 20 to 60 seconds, and the stop program segment time being 40 to 120 seconds.

[0021] Based on carbon nanotubes (MWCNTs) as a one-dimensional nano-reinforcing phase, which possesses both extremely high thermal conductivity and excellent structural stability, their composite with an aluminum matrix can significantly improve the thermal conductivity of the material. Simultaneously, the carbon nanotube / matrix interface can act as an irradiation defect trap, adsorbing vacancies and interstitial atomic point defects generated by high-energy particle bombardment, inhibiting the formation and growth of dislocation loops and voids, thereby enhancing the material's radiation resistance. This invention creatively employs an acoustic resonance mixer to coat carbon nanotubes with aluminum-based alloy powder, forming a continuous and dense carbon nanotube coating layer on the outer surface of the aluminum-based alloy powder. A three-dimensional solid geometric model is then established using modeling software, and the model is layered and slicing software is used to plan the laser scanning path, discretizing the three-dimensional entity into two-dimensional data. Based on the two-dimensional data, the aluminum-based alloy powder with the carbon nanotube coating layer is melted in a laser powder bed melting device to obtain a shaped aluminum-based composite material. The shaped aluminum-based composite material is then subjected to aging heat treatment to obtain a modified aluminum-based composite material. Further optimization of the encapsulation process for the acoustic resonance mixer includes: sequentially performing a mixing program segment - a shutdown program segment - a mixing program segment in a loop, with 8 to 12 loops, a mixing program segment duration of 20 to 60 seconds, and a shutdown program segment duration of 40 to 120 seconds.

[0022] The method for preparing modified aluminum-based composite materials provided by this invention significantly improves the radiation resistance of the composite material through the uniform coating and good interfacial bonding of carbon nanotubes in the aluminum matrix. The interface between carbon nanotubes and the matrix can adsorb and reduce point defects caused by radiation, inhibit the formation and growth of dislocation loops and void defects, thereby reducing problems such as surface blistering, abnormal increase in hardness, and decrease in elongation under radiation environment, and thus improving its mechanical properties. Secondly, based on the high thermal conductivity of carbon nanotubes, the tight bonding with the aluminum-based alloy promotes the rapid transfer of heat energy in the material, giving the composite material good heat dissipation performance. On the other hand, the preparation method provided by this invention can achieve uniform dispersion of carbon nanotubes in the aluminum-based alloy, reduce the performance inhomogeneity caused by agglomeration, and ensure the forming integrity of the modified composite material in complex structures, which is conducive to the integrated forming of components. The modified aluminum-based composite material prepared by this invention has excellent comprehensive properties of radiation resistance, high thermal conductivity, and high strength, and has a broader prospect for industrial application.

[0023] In a preferred embodiment, in step S1, the amount of carbon nanotubes added accounts for 1 to 3 wt% of the modified aluminum-based composite material, so that the high-density carbon nanotubes are uniformly coated on the aluminum-based alloy powder, thereby improving the thermal conductivity and radiation resistance of the modified composite material; more preferably, the material is subjected to a cooling treatment after cyclic treatment, and the cooling temperature is 30 to 40°C.

[0024] To further enable carbon nanotubes to form a continuous and dense coating layer on the surface of aluminum alloy matrix powder through programmed acoustic resonance mixing, the preferred particle size D50 of the aluminum alloy powder is 20~55μm, and the purity is >99%; the carbon nanotubes are multi-walled carbon nanotubes with an outer diameter of 11~45nm, a length of 11~55μm, and a purity ≥98%.

[0025] In a preferred embodiment, the acoustic resonance mixer has a gravitational acceleration of 0.1~1.0g, a resonance frequency of 45~60Hz, and an operating temperature of 65~70℃. In step S2, a three-dimensional solid geometric model of the target part is established using Solidworks software. Then, the model is sliced ​​into layers and a laser scanning path is planned using Magics software to discretize the three-dimensional solid into a series of two-dimensional data, which are saved and imported into the LPBF device. In step S3, the LPBF-150 laser powder bed melting equipment is used. This equipment mainly includes an IPG 500W fiber laser (maximum laser power of 500W, laser beam spot size of 70μm, laser wavelength of 1064μm), an inert gas protection system (O2<200ppm), a flexible automatic powder spreading device (with a scraper), a powder recovery system, a forming cylinder and a powder cylinder (maximum forming size of 150mm×150mm×300mm), and a computer forming control system.

[0026] In a preferred embodiment, step S3 specifically involves the following steps: First, an aluminum-based alloy powder with a carbon nanotube coating is uniformly spread onto a forming substrate using a powder spreading device. A laser beam scans the sliced ​​area line by line according to a pre-designed scanning path, causing the powder layer to melt rapidly, thereby obtaining the first two-dimensional plane of the part to be formed. Then, a computer control system lowers the forming substrate by one powder layer thickness, while the piston of the powder supply cylinder rises by one powder layer thickness. The powder spreading device then spreads another layer of aluminum-based alloy powder with a carbon nanotube coating on the outer surface of the part to be formed. The high-energy laser beam scans the second layer of powder according to the sliced ​​information to obtain the second two-dimensional plane of the part to be formed. The above steps are repeated, and the aluminum-based alloy powder with a carbon nanotube coating on the outer surface of the part to be formed is formed layer by layer until the part to be formed is completed, thus obtaining the formed aluminum-based composite material. In step S4, the aging heat treatment is preferably performed in a muffle furnace.

[0027] To further improve the flowability of aluminum-based alloy powder coated with carbon nanotubes, in step S3, preferably before melting treatment, a drying treatment is required, with a treatment temperature of 50~70℃ and a treatment time of 2~6h; more preferably, the starting temperature of the aging heat treatment is 20~40℃, the heating rate is 3~8℃ / min, the holding temperature is 280~370℃, and the holding time is 2~5h.

[0028] In another aspect, the present invention provides a modified aluminum-based composite material obtained by the preparation method of the modified aluminum-based composite material described above. This modified aluminum-based composite material possesses superior comprehensive properties, including radiation resistance, high thermal conductivity, and high strength, and has broader prospects for industrial applications.

[0029] In a preferred embodiment, the modified aluminum-based composite material comprises an aluminum alloy matrix and a carbon nanotube coating layer covering the outer surface of the aluminum alloy matrix. The carbon nanotube coating layer has a thickness of 10-20 nm and a density of 1.2-2.1 g / cm³. Preferably, the modified aluminum-based composite material has a thermal conductivity of 170-190 W / mK and a thermal diffusivity of 45-60 mm². 2 / s, which gives the modified aluminum-based composite material better thermal conductivity, radiation resistance and mechanical properties.

[0030] In another aspect, the present invention provides an application of the above-mentioned modified aluminum-based composite material in the fields of aerospace, nuclear industry or new energy vehicles.

[0031] The following detailed description is exemplary and intended to provide further detailed explanation of the invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this invention is for describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention.

[0032] Example 1 First, 3.0 wt% (percentage of the total mass of the composite material) of multi-walled carbon nanotube powder was mixed with aluminum-based alloy powder and added to an acoustic resonance mixer for coating treatment. The process parameters of the acoustic resonance mixer were: acceleration 0.4 g, mixing system temperature 69.1℃, and resonance frequency 54.2 Hz. The coating treatment process was carried out in a cycle of mixing program segment-stop program segment-mixing program segment 10 times. Each program segment was set to mix for 30 seconds and stop for 60 seconds. After all program segments were completed, the mixture was cooled to 40℃, thereby forming a continuous and dense carbon nanotube coating layer on the surface of the aluminum-based alloy powder. The aluminum-based alloy powder had a particle size D50 of 38.2 μm and a purity of 99.6%. The carbon nanotubes were multi-walled carbon nanotubes with an outer diameter of 15 nm, a length of 20 μm, and a purity of 98.5%.

[0033] Then, a three-dimensional solid geometric model of the target part was created using Solidworks software on a computer. Magics software was then used to slice and plan the scanning path of the three-dimensional solid model, discretizing it into a series of two-dimensional data. This data was saved and imported into the laser powder bed melting equipment. The laser process parameters were set as follows: laser power 300W, scanning speed 600mm / s, layer thickness 30μm, scanning spacing 60μm, using a partitioned island scanning strategy, and the laser scanning direction rotation angle between adjacent layers was 37°.

[0034] Secondly, an LPBF-150 laser powder bed melting equipment was used. This equipment is equipped with an IPG 500W fiber laser, an inert gas protection system (O2 < 200ppm), a flexible automatic powder spreading device (with a scraper), a powder recovery system, a forming cylinder and a powder cylinder, and a computer forming control system. Before forming, the sandblasted aluminum alloy substrate was fixed on the worktable of the laser powder bed melting forming equipment and leveled. After the forming cavity was evacuated, inert gas was introduced. The laser powder bed melting process is as follows: First, the powder to be processed is evenly spread on the forming substrate using a powder spreading device. The laser beam scans the sliced ​​area line by line according to a pre-designed scanning path, causing the powder layer to melt rapidly, thereby obtaining the first two-dimensional plane of the part to be formed. Then, the computer control system lowers the forming substrate by one powder layer thickness, while the piston of the powder supply cylinder rises by one powder layer thickness. The powder spreading device then lays a new layer of powder to be processed. The high-energy laser beam scans the second layer of powder according to the sliced ​​information to obtain the second two-dimensional plane of the part to be formed. Finally, the above steps are repeated, and the powder to be processed is formed layer by layer until the part to be formed is completed, thus obtaining the processed aluminum-based composite material. Before the melting process, a drying process is also required, with a processing temperature of 60℃ and a processing time of 4 hours.

[0035] Finally, the shaped aluminum-based composite material was subjected to aging heat treatment. The muffle furnace was set with an initial temperature of 30℃, a heating rate of 5℃ / min, a holding temperature of 325℃, and a holding time of 4 hours, followed by furnace cooling to room temperature. The resulting modified aluminum-based composite material had a carbon nanotube coating thickness of 18 nm, a density of 1.85 g / cm³, a thermal conductivity of 180.4 W / mK, and a thermal diffusivity of 56 mm². 2 / s. Figure 1 This is a surface morphology diagram of the modified aluminum-based composite material. Figure 2 This is a diagram of its surface appearance after irradiation.

[0036] Example 2 The only difference from Example 1 is that the weight of the multi-walled carbon nanotube powder is 2.5 wt% (percentage of the total mass of the composite material). A modified aluminum-based composite material was obtained, with a carbon nanotube coating thickness of 16 nm, a density of 1.72 g / cm³, a thermal conductivity of 176.8 W / mK, and a thermal diffusivity of 51 mm². 2 / s. Figure 3 This is a surface morphology diagram of the modified aluminum-based composite material after irradiation.

[0037] Example 3 The only difference from Example 1 is that the weight of the multi-walled carbon nanotube powder is 1.0 wt% (percentage of the total mass of the composite material). A modified aluminum-based composite material was obtained, with a carbon nanotube coating thickness of 12 nm, a density of 1.35 g / cm³, a thermal conductivity of 174.2 W / mK, and a thermal diffusivity of 49 mm². 2 / s. Figure 4 The image shows the surface morphology of the object after irradiation.

[0038] Comparative Example 1 The only difference from Example 1 is that steps S1 and S2 were not performed. A modified aluminum-based composite material was obtained, which lacked a carbon nanotube coating. The modified aluminum-based composite material had a thermal conductivity of 160.6 W / mK and a thermal diffusivity of 45 mm². 2 / s. Figure 5 The image shows the surface morphology of the object after irradiation.

[0039] Comparative Example 2 The only difference from Example 1 is that carbon nanotubes and aluminum alloy powder are directly mechanically mixed. This yields a modified aluminum-based composite material with a carbon nanotube coating thickness of 6 nm, a density of 0.62 g / cm³, a thermal conductivity of 155.4 W / mK, and a thermal diffusivity of 48 mm². 2 / s. Figure 6 The image shows the surface morphology of the object after irradiation.

[0040] Comparative Example 3 The only difference from Example 1 is that the weight of the multi-walled carbon nanotube powder is 0.05 wt% (percentage of the total mass of the composite material). A modified aluminum-based composite material was obtained, with a carbon nanotube coating thickness of 3 nm, a density of 0.28 g / cm³, a thermal conductivity of 162.7 W / mK, and a thermal diffusivity of 47 mm². 2 / s.

[0041] Performance testing: 1) Thermal conductivity Thermal conductivity was tested using the laser flash method with a Netzsch LFA 467 laser flash thermal conductivity meter. The sample size was a φ10mm × 2mm circular disc, which was mechanically ground and polished before testing at room temperature (25℃) under an inert atmosphere. The testing principle was as follows: a pulsed laser instantaneously heated one side of the sample surface, and an infrared detector recorded the temperature rise curve of the other side. The thermal diffusivity was calculated based on the thermal diffusion response time, and then combined with the material density and specific heat capacity to obtain the thermal conductivity.

[0042] 2) Radiation resistance Radiation resistance was evaluated using an ion irradiation simulation experiment. The irradiation equipment was a 200kV ion implanter, employing He... + Ions were injected at an energy of 200 keV at a dose rate of 2.0 × 10¹³ ions / cm², and the irradiation temperature was controlled at room temperature. After irradiation, the surface morphology changes of the material were observed using a scanning electron microscope (FEI Nova NanoSEM 450), and the proportion of bubbling area and the average diameter of the bubble caps were statistically analyzed using image analysis software. The testing principle is that high-energy ion bombardment of the material generates dislocation loops and void defects, which manifest as a bubble bulging structure on the surface. The number and size of these bubbles reflect the material's radiation resistance stability.

[0043] 3) Mechanical properties Mechanical properties were evaluated through microhardness testing and room temperature tensile testing. Microhardness was tested using an HXD-1000TM Vickers microhardness tester under a load of 200g and a holding time of 15s. Five different locations were tested on each specimen, and the average value was taken. Tensile properties were tested using an Instron 5982 universal testing machine. Specimens were prepared according to GB / T 228.1 standards, and the loading rate was 1mm / min. The testing principle is to evaluate the strength and deformation capacity of the material by observing its plastic deformation and fracture behavior under external load.

[0044] The above-described embodiments and comparative examples were subjected to the above-described performance tests, and the test results are shown in Table 1.

[0045] Table 1 The following technical effects can be obtained from the test results of the above embodiments and comparative examples: The thermal conductivity test results show that the thermal conductivity of Example 1 reaches 180.4 W / mK, significantly higher than that of Comparative Example 1 (160.6 W / mK), indicating that the continuous and dense coating of carbon nanotubes significantly improves the thermal conductivity. The radiation resistance test results show that after irradiation, the blistering area of ​​Example 1 is only 8%, and the average bubble diameter is 32 nm, significantly better than Comparative Example 1 (blistering area 19%, bubble diameter 68 nm), indicating that the carbon nanotube / matrix interface effectively inhibits defect aggregation and void growth. The mechanical property test results show that the hardness and tensile strength of the material in Example 1 are significantly higher than those of the uncoated comparative material, and the performance degradation after irradiation is smaller, indicating that the carbon nanotube reinforcing phase improves structural stability under irradiation while enhancing strength.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a modified aluminum-based composite material, characterized in that, The preparation method includes: Step S1: Carbon nanotubes and aluminum-based alloy powder are coated in an acoustic resonance mixer to obtain aluminum-based alloy powder with a carbon nanotube coating layer on the outer surface. Step S2: A three-dimensional solid geometric model is established using modeling software, and the model is sliced ​​into layers and the laser scanning path is planned using slicing software to discretize the three-dimensional solid into two-dimensional data. Step S3: Based on the two-dimensional data, the aluminum-based alloy powder with a carbon nanotube coating on its outer surface is melted in a laser powder bed melting device to obtain a shaped aluminum-based composite material. Step S4: Take the processed aluminum-based composite material and perform aging heat treatment to obtain the modified aluminum-based composite material; The encapsulation process of the acoustic resonance mixer includes: performing a mixing program segment-stop program segment-mixing program segment cycle 8 to 12 times in sequence, wherein the mixing program segment time is 20 to 60 seconds and the stop program segment time is 40 to 120 seconds.

2. The preparation method according to claim 1, characterized in that, In step S1, the amount of carbon nanotubes added accounts for 1-3 wt% of the modified aluminum-based composite material; and / or, The cycle process is followed by a cooling process at a temperature of 30-40°C.

3. The preparation method according to claim 1, characterized in that, The aluminum-based alloy powder has a particle size D50 of 20~55μm and a purity >99%; and / or, The carbon nanotubes are multi-walled carbon nanotubes with an outer diameter of 11-45 nm, a length of 11-55 μm, and a purity of ≥98%.

4. The preparation method according to claim 1, characterized in that, The acoustic resonance mixer has a gravitational acceleration of 0.1~1.0g, a resonance frequency of 45~60Hz, and an operating temperature of 65~70℃; and / or, In step S4, the aging heat treatment is carried out in a muffle furnace.

5. The preparation method according to claim 1, characterized in that, In step S3, before the melting process, a drying process is required, with a processing temperature of 50~70℃ and a processing time of 2~6h.

6. The preparation method according to claim 4, characterized in that, The starting temperature of the aging heat treatment is 20~40℃, the heating rate is 3~8℃ / min, the holding temperature is 280~370℃, and the holding time is 2~5h.

7. A modified aluminum-based composite material, characterized in that, The modified aluminum-based composite material is obtained by the preparation method of the modified aluminum-based composite material according to any one of claims 1 to 6.

8. The modified aluminum-based composite material according to claim 7, characterized in that, The modified aluminum-based composite material includes an aluminum alloy matrix and a carbon nanotube coating layer covering the outer surface of the aluminum alloy matrix. The carbon nanotube coating layer has a thickness of 10~20nm and a density of 1.2~2.1g / cm³.

9. The modified aluminum-based composite material according to claim 7 or 8, characterized in that, The modified aluminum-based composite material has a thermal conductivity of 170~190 W / mK and a thermal diffusivity of 45~60 mm. 2 / s.

10. The application of a modified aluminum-based composite material according to any one of claims 7 to 9 in the fields of aerospace, nuclear industry or new energy vehicles.

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