High-dispersion carbon nanotube alloy particles, preparation method and application thereof, and method for preparing aluminum-based composite material

Abstract

The invention relates to the technical field of aluminum-based composite materials, and discloses high-dispersion carbon nanotube alloy particles, a preparation method and application thereof and a method for preparing an aluminum-based composite material. Comprising the following steps: burdening according to aluminum alloy components, and heating raw materials to a molten state to obtain mother alloy melt; and a gas atomization method is adopted, high-pressure inert atmosphere loaded with carbon nanotubes is used for impacting the mother alloy melt, the mother alloy melt is crushed into fine mother alloy molten drops, the surfaces of the carbon nanotubes are coated with the fine mother alloy molten drops, and the high-dispersion carbon nanotube alloy particles are obtained after cooling. According to the method, the carbon nanotube alloy particles are prepared in one step through the gas atomization method and used for preparing the aluminum-based composite material, structural damage and impurity introduction of the carbon nanotubes are effectively avoided, the dispersion and prefabrication efficiency of the carbon nanotubes is improved, and batch production is facilitated.

Description

Technical Field

[0001] This invention relates to the field of aluminum-based composite materials technology, specifically to highly dispersed carbon nanotube alloy particles, their preparation methods and applications, and methods for preparing aluminum-based composite materials. Background Technology

[0002] Aluminum-based composites have become an ideal choice for lightweight materials due to their significant advantages such as high specific strength, excellent wear resistance, and fatigue resistance. Currently, the main methods for preparing aluminum-based composites include powder metallurgy, pressure infiltration, and stir melting. However, these methods generally face challenges in dispersing and preforming nano-reinforcing materials.

[0003] In the mixing process of carbon nanotubes and aluminum / aluminum alloy powder, traditional ball milling transfers energy to aluminum particles and carbon nanotubes through continuous collisions of steel balls. This causes the aluminum particles to undergo cold welding, plastic deformation, atomic disorder, and dislocations, leading to raw material embrittlement and aluminum powder fragmentation. Simultaneously, carbon nanotubes exhibit truncation and an increase in amorphous carbon content. With prolonged ball milling, the damage to carbon nanotubes intensifies, amorphization and amorphization become more severe, and the amount of amorphous carbon generated increases accordingly. During sintering, this amorphous carbon reacts with aluminum to form Al4C3. Researchers have been exploring alternative or auxiliary methods, such as solution mixing, molecular-level mixing, and in-situ chemical vapor deposition, to achieve uniform dispersion of carbon nanotubes while better preserving their intact structure. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of carbon nanotube structure being damaged and difficulty in uniform dispersion during the mixing process of carbon nanotubes and aluminum / aluminum alloy powders. This invention provides highly dispersed carbon nanotube alloy particles, their preparation method and application, and a method for preparing aluminum-based composite materials. This method prepares carbon nanotube alloy particles in one step through gas atomization and uses them for the preparation of aluminum-based composite materials. It effectively avoids structural damage to carbon nanotubes and the introduction of impurities, improves the dispersion and prefabrication efficiency of carbon nanotubes, and is conducive to mass production.

[0005] To achieve the above objectives, the present invention provides a method for preparing highly dispersed carbon nanotube alloy particles, comprising: The raw materials are prepared according to the aluminum alloy composition and heated to a molten state to obtain the master alloy melt. The gas atomization method is used to impact the molten master alloy with a high-pressure inert atmosphere carrying carbon nanotubes, breaking the molten master alloy into fine master alloy droplets. The fine master alloy droplets coat the surface of the carbon nanotubes, and after cooling, highly dispersed carbon nanotube alloy particles are obtained.

[0006] Preferably, the temperature of the master alloy melt is 700~800℃.

[0007] Preferably, the pressure of the high-pressure inert atmosphere is 2.5~4MPa, and the flow rate is 50~70 L·s. -1 .

[0008] A second aspect of the present invention provides highly dispersed carbon nanotube alloy particles prepared by the above-described preparation method.

[0009] Preferably, the particle size of the highly dispersed carbon nanotube alloy particles is 50~200μm.

[0010] Preferably, the carbon nanotube content in the highly dispersed carbon nanotube alloy particles is 2~5.5 wt%.

[0011] A third aspect of the present invention provides the application of the above-mentioned highly dispersed carbon nanotube alloy particles in the preparation of aluminum-based composite materials.

[0012] A fourth aspect of the present invention provides a method for preparing an aluminum-based composite material, comprising: The above-mentioned highly dispersed carbon nanotube alloy particles were mixed with aluminum alloy melt, stirred and smelted, and then cast to obtain a low-content carbon nanotube reinforced aluminum matrix composite material. Alternatively, the above-mentioned highly dispersed carbon nanotube alloy particles can be directly hot-pressed and sintered to obtain a high-carbon nanotube-reinforced aluminum-based composite material.

[0013] Preferably, the chemical composition of the aluminum alloy melt is the same as that of the master alloy melt.

[0014] Preferably, the temperature for stirring and melting is 700~750℃, and the stirring speed is 150~250r / min.

[0015] Preferably, in the low-carbon nanotube reinforced aluminum matrix composite material, the carbon nanotube content is 0.5~1.5wt%.

[0016] Preferably, the hot pressing sintering conditions include: a temperature of 500~550℃, a pressure of 40~60 N / mm, and a time of 3~5h.

[0017] Preferably, the carbon nanotube content in the high-carbon nanotube reinforced aluminum matrix composite material is 2 to 5.5 wt%.

[0018] The present invention has the following beneficial effects: This invention provides a one-step preparation method for highly dispersed carbon nanotube alloy particles via gas atomization, avoiding structural damage issues associated with traditional ball milling methods, such as truncation, increased amorphous carbon content, and harmful reactions like Al4C3 formation. This ensures the integrity and high performance of the carbon nanotubes. Furthermore, the preparation method provided by this invention is simple to operate, significantly improving the dispersion and pre-fabrication efficiency of carbon nanotubes, facilitating mass production, reducing production costs, and meeting the industrial demand for efficient and stable preparation processes. By adjusting the mass fraction of carbon nanotubes and key parameters in the preparation process, such as melting, casting, and hot-pressing sintering, the properties of aluminum-based composite materials can be flexibly controlled to meet the specific needs of different application scenarios. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the preparation system for highly dispersed carbon nanotube alloy particles of the present invention; Figure 2 Here is a SEM image of the highly dispersed carbon nanotube alloy particles from Example 3; Figure 3 This is a SEM image of the highly dispersed carbon nanotube alloy particles from Example 4.

[0020] Explanation of reference numerals in the attached figures 1. Carbon nanotube storage tank; 2. Atomizing powder making device; 21. Pneumatic vacuum conveyor; 22. Atomizing chamber; 23. Atomizing nozzle; 24. Atomizing zone; 25. Guide pipe; 211. Feed inlet; 212. Air inlet; 213. Discharge outlet; 221. Feed port. Detailed Implementation

[0021] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0022] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0023] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0024] Furthermore, the technical solutions provided in the various embodiments of the present invention can be combined with each other, but only if they are feasible to those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0025] This invention provides a method for preparing highly dispersed carbon nanotube alloy particles, comprising: The raw materials are prepared according to the aluminum alloy composition and heated to a molten state to obtain the master alloy melt. The gas atomization method is used to impact the molten master alloy with a high-pressure inert atmosphere carrying carbon nanotubes, breaking the molten master alloy into fine master alloy droplets. The fine master alloy droplets coat the surface of the carbon nanotubes, and after cooling, highly dispersed carbon nanotube alloy particles are obtained.

[0026] The aluminum alloy in this invention is a conventional aluminum alloy in the art. The raw materials are mixed and heated to a molten state according to the required finished aluminum alloy product to obtain a master alloy melt.

[0027] Preferably, the temperature of the master alloy melt is 700~800℃; wherein the heating time is sufficient to ensure that all raw materials are heated to the molten state.

[0028] Preferably, the pressure of the high-pressure inert atmosphere is 2.5~4MPa, and the flow rate is 50~70 L·s. -1 .

[0029] In this invention, pressure refers to relative pressure (gauge pressure).

[0030] The inert atmosphere of the present invention may be selected from one or more of nitrogen, helium, neon, argon, krypton and xenon.

[0031] In specific embodiments, the preparation method of the highly dispersed carbon nanotube alloy particles of the present invention can be carried out in a manner such as... Figure 1 The preparation system for highly dispersed carbon nanotube alloy particles shown is implemented in the system, which includes a carbon nanotube storage tank 1 and an atomizing powder preparation device 2 connected to the nanotube storage tank 1; the atomizing powder preparation device 2 can be a conventional atomizing powder preparation device in the art.

[0032] Specifically, the atomizing powder-making device 2 includes a pneumatic vacuum conveyor 21 and an atomizing chamber 22. The pneumatic vacuum conveyor 21 is provided with a feed inlet 211, an air inlet 212 and a discharge outlet 213. The nanotube storage tank 1 is connected to the feed inlet 211 through a pipe. The air inlet 212 is connected to a high-pressure gas storage tank. The discharge outlet 213 is connected to the feed port 221 of the atomizing chamber 22.

[0033] In use, a high-pressure inert atmosphere is delivered from the inlet 212 to the pneumatic vacuum conveyor 21, creating a negative pressure airflow in the pipe at the feed inlet 211. This draws in the dried carbon nanotube powder from the carbon nanotube storage tank 1, resulting in a high-pressure inert atmosphere carrying the dried carbon nanotube powder. This atmosphere is then delivered to the outlet 213. The high-pressure inert atmosphere carrying the carbon nanotubes then enters the atomizing airflow channel of the atomizing chamber 22 through the feed inlet 221. It is then ejected from the atomizing nozzle 23 (which may be a free-fall nozzle or a confined nozzle) and impacts the master alloy melt flowing into the atomizing zone 24 through the guide pipe 25. In the atomizing zone 24, the master alloy melt is broken and dispersed by the high-pressure inert atmosphere carrying the carbon nanotubes, forming fine master alloy droplets. With the carbon nanotubes as heterogeneous nucleation cores, the fine master alloy droplets further coat the surface of the carbon nanotubes. They then rapidly cool and solidify into spherical powder, resulting in highly dispersed carbon nanotube alloy particles.

[0034] Furthermore, in this invention, the pressure and flow rate of the high-pressure inert atmosphere refer to the pressure and flow rate of the high-pressure inert atmosphere when it enters the pneumatic vacuum conveyor 21.

[0035] Preferably, the guide tube 25 directly controls the size of the droplets of the master alloy solution being dripped in. In order to ensure a better coating effect, the diameter of the guide tube 25 is more suitable to be 2~4 mm.

[0036] In this invention, because the carbon nanotubes are nanoscale in size, they will agglomerate during initial use. Therefore, in actual operation, several carbon nanotubes are usually agglomerated together to form an agglomerate. This agglomerate serves as a heterogeneous nucleation core, and the fine master alloy droplets will coat the surface of the agglomerate formed by the several carbon nanotubes.

[0037] A second aspect of the present invention provides highly dispersed carbon nanotube alloy particles prepared by the above-described preparation method.

[0038] Preferably, the particle size of the highly dispersed carbon nanotube alloy particles is 50~200μm; the carbon nanotube content in the highly dispersed carbon nanotube alloy particles is 2~5.5 wt%.

[0039] In this invention, the particle size of the final highly dispersed carbon nanotube alloy particles and the content of carbon nanotubes in the highly dispersed carbon nanotube alloy particles can be controlled by controlling the pressure and flow rate of the high-pressure inert atmosphere (the content of carbon nanotubes introduced can be controlled by controlling the pressure and flow rate of the high-pressure inert atmosphere).

[0040] A third aspect of the present invention provides the application of the above-mentioned highly dispersed carbon nanotube alloy particles in the preparation of aluminum-based composite materials.

[0041] A fourth aspect of the present invention provides a method for preparing an aluminum-based composite material, comprising: The above-mentioned highly dispersed carbon nanotube alloy particles were mixed with aluminum alloy melt, stirred and smelted, and then cast to obtain a low-content carbon nanotube reinforced aluminum matrix composite material. Alternatively, the above-mentioned highly dispersed carbon nanotube alloy particles can be directly hot-pressed and sintered to obtain a high-carbon nanotube-reinforced aluminum-based composite material.

[0042] In this invention, the chemical composition of the aluminum alloy melt is the same as that of the master alloy melt.

[0043] Preferably, the temperature for stirring and melting is 700~750℃, and the stirring speed is 150~250r / min.

[0044] In one specific implementation, the stirring and melting time is 10 minutes.

[0045] In a preferred embodiment, the carbon nanotube content in the low-carbon nanotube-reinforced aluminum matrix composite material can be controlled by controlling the ratio of highly dispersed carbon nanotube alloy particles to aluminum alloy melt; in the low-carbon nanotube-reinforced aluminum matrix composite material of the present invention, the carbon nanotube content is 0.5~1.5wt%.

[0046] In a preferred embodiment of the present invention, the conditions for hot pressing sintering include: a temperature of 500~550℃, a pressure of 40~60 N / mm, and a time of 3~5h.

[0047] In a preferred embodiment, the carbon nanotube content in the high-carbon nanotube reinforced aluminum matrix composite material is 2 to 5.5 wt%.

[0048] The present invention will be described in detail below through embodiments. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.

[0049] Example 1 (1) According to the aluminum alloy composition: Cu: 0.50wt%, Zn: 0.50wt%, Si: 1.10wt%, Mg: 3.60wt%, Mn: 0.80wt%, Ti: 0.12wt%, weigh the intermediate alloy of each element and pure aluminum ingots for batching. Mix all the raw materials in the atomizing powder making device 2 and heat them to the molten state to obtain the master alloy melt. The temperature of the master alloy melt is 750℃. (2) A high-pressure inert atmosphere (high-purity argon) is supplied from the inlet 212 to the vacuum conveyor 21. The pressure of the high-pressure inert atmosphere is 3.0 MPa and the flow rate is 50 L·s. -1This creates a negative pressure airflow within the pipe at the inlet 211, drawing the dried carbon nanotube powder from the carbon nanotube storage tank 1 through the inlet 211. This results in a high-pressure inert atmosphere carrying carbon nanotubes, which is then conveyed to the outlet 213. This high-pressure inert atmosphere carrying carbon nanotubes then enters the atomizing airflow channel of the atomizing chamber 22 through the feed port 221. The molten master alloy is then guided through the guide pipe 25 (the guide pipe 25 has a diameter of 3...). The carbon nanotubes are dropped into the atomization zone 24 using a gas atomization method. The high-pressure inert atmosphere carrying carbon nanotubes is ejected from the atomization nozzle 23 (free fall nozzle) and impacts the master alloy melt flowing into the atomization zone 24 through the guide tube 25. In the atomization zone 24, the master alloy melt is broken and dispersed by the high-pressure inert atmosphere carrying carbon nanotubes to form fine master alloy droplets. With carbon nanotubes as heterogeneous nucleation cores, the fine master alloy droplets will further coat the surface of carbon nanotubes. Then, they are rapidly cooled and solidified into spherical powders to obtain highly dispersed carbon nanotube alloy particles.

[0050] Example 2 The method was implemented according to Example 1, except that the pressure of the high-pressure inert atmosphere was 3.5 MPa and the flow rate was 60 L·s. -1 Highly dispersed carbon nanotube alloy particles were obtained.

[0051] Example 3 A highly dispersed carbon nanotube alloy particle with a particle size of 150~200μm; the carbon nanotube content is 2.8wt% as detected by a carbon-sulfur analyzer. The highly dispersed carbon nanotube alloy particle is prepared by the method of Example 1.

[0052] Example 4 A highly dispersed carbon nanotube alloy particle with a particle size of 80~150μm was prepared by a carbon-sulfur analyzer. The particle size of the highly dispersed carbon nanotube alloy particle was 80~150μm. The carbon nanotube content was 4.5wt%. The highly dispersed carbon nanotube alloy particle was prepared by the method of Example 2.

[0053] Example 5 The carbon nanotubes in the highly dispersed carbon nanotube alloy particles in Examples 3-4 have good integrity and dispersion, and can be used to prepare aluminum-based composite materials.

[0054] Example 6 The highly dispersed carbon nanotube alloy particles of Example 3 were mixed with aluminum alloy melt (the chemical composition of which was the same as that of the master alloy melt in Example 1). The ratio of the highly dispersed carbon nanotube alloy particles to the aluminum alloy melt was controlled, and the mixture was slowly stirred (at a speed of 60 r / min) to dissolve the highly dispersed carbon nanotube alloy particles. Then, stirring and melting were carried out at a stirring speed of 200 r / min, the stirring and melting temperature was 720°C, and the stirring and melting time was 10 min. After stirring was stopped, the mixture was quickly cast into a preheated metal mold to obtain a low-carbon nanotube reinforced aluminum-based composite material. The carbon nanotube content in this low-carbon nanotube reinforced aluminum-based composite material was 1 wt%.

[0055] Example 7 The method of Example 6 was implemented, except that the highly dispersed carbon nanotube alloy particles used were the same as those in Example 4, and the carbon nanotube content in the low-content carbon nanotube reinforced aluminum matrix composite material was 1.5 wt% by controlling the ratio of the highly dispersed carbon nanotube alloy particles to the aluminum alloy melt.

[0056] Example 8 The highly dispersed carbon nanotube alloy particles of Example 3 were loaded into a hot-pressing sintering mold and directly subjected to vacuum hot-pressing sintering. The hot-pressing sintering conditions included a temperature of 520°C, a pressure of 50 N / mm, and a time of 4 h. After molding, a high-carbon nanotube-reinforced aluminum-based composite material was obtained. The carbon nanotube content in this high-carbon nanotube-reinforced aluminum-based composite material was 2.8 wt%.

[0057] Example 9 The method of Example 8 was implemented, except that the highly dispersed carbon nanotube alloy particles used were the highly dispersed carbon nanotube alloy particles of Example 4, to obtain a high-content carbon nanotube reinforced aluminum matrix composite material; in this high-content carbon nanotube reinforced aluminum matrix composite material, the carbon nanotube content is 4.5 wt%.

[0058] Test Example 1 The highly dispersed carbon nanotube alloy particles of Examples 3 and 4 were observed by SEM. The SEM image of the highly dispersed carbon nanotube alloy particles of Example 3 is shown below. Figure 2 As shown, the SEM image of the highly dispersed carbon nanotube alloy particles in Example 4 is as follows. Figure 3 As shown, from Figure 2 and Figure 3As can be seen, the prepared highly dispersed carbon nanotube alloy particles exhibit a good spherical morphology and a relatively smooth surface. When the pressure of the high-pressure inert atmosphere is increased from 3 MPa to 3.5 MPa, the kinetic energy of the atomizing gas and the amount of carbon nanotubes transported are increased, resulting in a larger carbon nanotube loading. The molten master alloy is broken into finer droplets, and the average particle size decreases from 162.5 μm to 132.4 μm. The resulting highly dispersed carbon nanotube alloy particles are finer and have a higher carbon nanotube content.

[0059] The results above show that the one-step preparation of carbon nanotube alloy particles using the gas atomization method of this invention, and its application in the preparation of aluminum-based composite materials, can effectively avoid structural damage to carbon nanotubes and the introduction of possible impurities. It has significant advantages such as simple process flow, convenient operation, and high preparation efficiency.

[0060] It should be understood that any parts not described in detail in this specification belong to the prior art.

[0061] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing highly dispersed carbon nanotube alloy particles, characterized in that, include: The raw materials are prepared according to the aluminum alloy composition and heated to a molten state to obtain the master alloy melt. The gas atomization method is used to impact the molten master alloy with a high-pressure inert atmosphere carrying carbon nanotubes, breaking the molten master alloy into fine master alloy droplets. The fine master alloy droplets coat the surface of the carbon nanotubes, and after cooling, highly dispersed carbon nanotube alloy particles are obtained.

2. The preparation method according to claim 1, characterized in that, The temperature of the master alloy melt is 700~800℃.

3. The preparation method according to claim 1 or 2, characterized in that, The pressure of the high-pressure inert atmosphere is 2.5~4MPa, and the flow rate is 50~70 L·s. -1 .

4. Highly dispersed carbon nanotube alloy particles prepared by the preparation method according to any one of claims 1 to 3.

5. The highly dispersed carbon nanotube alloy particles according to claim 4, characterized in that, The highly dispersed carbon nanotube alloy particles have a particle size of 50~200μm; and / or The carbon nanotube content in the highly dispersed carbon nanotube alloy particles is 2~5.5 wt%.

6. The application of the highly dispersed carbon nanotube alloy particles according to claim 4 or 5 in the preparation of aluminum-based composite materials.

7. A method for preparing aluminum-based composite materials, characterized in that, include: The highly dispersed carbon nanotube alloy particles described in claim 4 or 5 are mixed with aluminum alloy melt, stirred and smelted, and then cast to obtain a low-content carbon nanotube reinforced aluminum-based composite material. Alternatively, the highly dispersed carbon nanotube alloy particles described in claim 4 or 5 can be directly subjected to hot pressing and sintering to obtain a high-content carbon nanotube-reinforced aluminum-based composite material.

8. The method according to claim 7, characterized in that, The chemical composition of the aluminum alloy melt is the same as that of the master alloy melt.

9. The method according to claim 7 or 8, characterized in that, The temperature for stirring and melting is 700~750℃, and the stirring speed is 150~250r / min.

10. The method according to claim 7, characterized in that, In the low-carbon nanotube reinforced aluminum matrix composite material, the carbon nanotube content is 0.5~1.5wt%.

11. The method according to claim 7, characterized in that, The conditions for hot pressing sintering include: a temperature of 500~550℃, a pressure of 40~60 N / mm, and a time of 3~5h.

12. The method according to claim 7 or 11, characterized in that, In the high-carbon nanotube-reinforced aluminum matrix composite material, the carbon nanotube content is 2~5.5 wt%.

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