A method for preparing aluminum-based composite material modified by ball-milling carbon nanotubes at high temperature

Abstract

The invention discloses a preparation method of a milled carbon nanotube modified aluminum-based composite material, characterized in that it comprises the following steps: step 1: premixing carbon nanotubes and copper powder to form a preform of carbon nanotubes and copper; step 2: placing the preform of carbon nanotubes and copper and an aluminum ingot in a ball mill, heating the ball mill, and placing ball milling beads; step 3: ball milling the preform of carbon nanotubes and copper, the aluminum ingot and the ball milling beads in the ball mill for a preset time at a preset speed, filtering the ball milling product under a preset temperature environment after the ball milling, sieving out the ball milling beads, and obtaining a milled carbon nanotube modified aluminum-based composite material. The traditional powder metallurgy and stirring casting are combined into one, the production efficiency is greatly improved, and it has a high practical production guidance significance.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy preparation, and in particular to a method for preparing an aluminum-based composite material modified by ball-milling carbon nanotubes at high temperature. Background Art

[0002] Aluminum and its alloys have excellent properties such as light weight, corrosion resistance, good thermal conductivity and electrical conductivity. They have become key materials in major national fields such as aerospace, transportation, etc., and are widely used in important parts such as aircraft main structure, skin, and automobile structure. Since the discovery of carbon nanotubes (CNTs) in 1991, they have been widely used by scholars at home and abroad because of their special sp2 hybridization of carbon atoms in their structure, low density, high specific surface area and large aspect ratio, excellent electrical and thermal conductivity, ultra-high tensile strength (~60GPa) and elastic modulus (~1TPa). They are ideal reinforcements for metal matrix composites and have received extensive attention from scholars at home and abroad. However, although the traditional powder metallurgy process can produce high-performance aluminum matrix composites, the process flow is relatively long; and the stirring casting process with higher production efficiency cannot produce high-performance materials due to the density difference between carbon nanotubes and aluminum.

[0003] The Chinese patent document with the publication number CN109020590B discloses a method for preparing a carbon nanotube-enhanced alumina-based composite material by a spray pyrolysis hot pressing method, which belongs to the technical field of composite material preparation. The invention adds pretreated carbon nanotubes and sodium dodecyl sulfate into deionized water to prepare a carbon nanotube dispersion, adds aluminum nitrate to prepare a carbon nanotube / aluminum salt solution, generates a carbon nanotube / aluminum hydroxide sol by adding ammonia water, atomizes the carbon nanotube / aluminum hydroxide sol into small droplets, evaporates the water in the droplets in a short time through a pyrolysis furnace, decomposes aluminum hydroxide into amorphous aluminum oxide, and simultaneously coats the carbon nanotubes dispersed evenly in the droplets to obtain spherical particles of amorphous aluminum oxide-coated carbon nanotubes with relatively uniform particle size, and spherical powders are subjected to hot pressing and sintering to generate carbon nanotube-enhanced alumina-based composite materials. However, this method is complex and not suitable for mass production. The Chinese patent document with the publication number CN110938764B discloses a method for preparing a carbon nanotube / aluminum composite material with high mechanical strength and high conductivity, comprising the following steps: Step 1: Take a single-walled carbon nanotube with a tube diameter of less than 6nm, etch the cap end of the carbon nanotube with an etchant at high temperature to obtain a single-walled carbon nanotube with an open end; Step 2: By controlling the ball milling time or the growth time of the carbon nanotube, an open-ended single-walled carbon nanotube with an aspect ratio of about 250 is obtained. By coating a layer of boride or rare earth coating with excellent wettability with the aluminum matrix on the surface of the single-walled carbon nanotube, its compatibility with the aluminum matrix is ​​improved, so that it is evenly distributed in the aluminum matrix. At the same time, high-temperature annealing treatment increases the diffusion of metal atoms and the like between carbon tubes. These treatments effectively improve the overall mechanical properties and conductivity of the carbon nanotube aluminum composite material. However, this method requires etching the cap end of the carbon nanotube with an etchant at high temperature, and the fault tolerance rate is low.

[0004] Therefore, there is still a lack of a simple and efficient method for preparing carbon nanotube-modified aluminum-based composite materials. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a ball-milled carbon nanotube modified aluminum-based composite material at high temperature. The method combines traditional powder metallurgy and stirring casting, shortens the process flow, greatly improves production efficiency, and has a high practical production guidance significance.

[0006] To achieve this purpose, the present invention provides a method for preparing a milled carbon nanotube-modified aluminum-based composite material, which comprises the following steps:

[0007] Step 1: premix the carbon nanotubes and copper powder to form a preform of carbon nanotubes and copper. This design coats the surface of the carbon nanotubes with a layer of copper to increase wettability with the aluminum substrate.

[0008] Step 2: Place the carbon nanotube and copper preforms and the aluminum ingot in a ball mill, heat the ball mill, and put in the ball mill beads. The above design adds a heating function to the ball mill of the traditional planetary ball mill, which can heat the ball mill to a temperature above the liquidus of aluminum and melt the aluminum.

[0009] Step 3: In a ball mill, the carbon nanotube and copper preform, the aluminum ingot and the ball milling beads are ball milled for a preset time at a preset speed. After the ball milling, the ball milling product is filtered under a preset temperature environment to screen out the ball milling beads to obtain a ground carbon nanotube-modified aluminum-based composite material. The above-mentioned designed carbon nanotubes have also been evenly dispersed in the aluminum liquid. At this time, the aluminum liquid and the ball milling beads in the ball milling tank are poured onto a sieve made of steel wire mesh under a high temperature environment. The aluminum liquid flows through the sieve and the ball milling beads remain on the sieve, thereby achieving a filtering effect.

[0010] In step 1 of the above technical solution, the carbon nanotubes and copper powder are pre-mixed by a high-speed shearing machine, and the speed of the high-speed shearing machine is 1000-5000 r / min. If the speed is lower than 1000 r / min, the carbon nanotubes and copper powder cannot be tightly combined, and if the speed is higher than 5000 r / min, the structure of the carbon nanotubes will be destroyed.

[0011] In step 1 of the above technical solution, the mass percentage of carbon nanotubes in the carbon nanotube and copper preform is 1-20wt%. If the mass percentage is lower than 1wt%, the strengthening effect will not be achieved, and if the mass percentage is higher than 20wt%, copper will not form an effective wetting layer.

[0012] In step 2 of the above technical solution, the carbon nanotube and copper preform accounts for 1-10wt.% of the total mass of the carbon nanotube and copper preform and the aluminum ingot. If the mass percentage is lower than 1wt.%, the strengthening effect will not be achieved, and if the mass percentage is higher than 10wt.%, the preform will be difficult to disperse in the matrix.

[0013] In step 2 of the above technical solution, the ball mill is heated at a temperature of 500-800° C. If the temperature is lower than 500° C., the aluminum liquid will solidify, and if the temperature is higher than 800° C., the carbon nanotubes will be ablated.

[0014] In step 2 of the above technical solution, the mass of the ball milling beads is 9 to 11 times that of the ball milling material.

[0015] In step 3 of the above technical solution, the speed of ball milling in the ball mill is 100 to 2000 r / min. If the speed is lower than 100 r / min, the carbon nanotubes cannot be evenly dispersed in the aluminum liquid, and if the speed is higher than 2000 r / min, the structure of the carbon nanotubes will be destroyed.

[0016] In step 3 of the above technical solution, the ball milling time in the ball mill is 0.5 to 10 hours.

[0017] In step 3 of the above technical solution, after the ball milling is completed, the ball milling product is filtered at a temperature of 500-800° C. When the temperature is lower than 500° C., the aluminum liquid will solidify, and when the temperature is higher than 800° C., the carbon nanotubes will be ablated.

[0018] In step 3 of the above technical solution, after the ball milling is completed, the ball milling product is filtered using a filter screen made of a wire mesh. Using other filter screens may cause ablation and introduce impurities.

[0019] Beneficial effects of the present invention:

[0020] The present invention improves the interface bonding between the carbon nanotubes and the aluminum liquid by pre-bonding the copper powder and the carbon nanotubes;

[0021] At present, the industry needs to first prepare a preform by powder metallurgy, and then use high-temperature smelting to melt the preform after powder metallurgy into the matrix material. The present invention is equivalent to smelting and ball milling at the same time, which can not only use the resistance of aluminum liquid to reduce the damage of carbon nanotube structure caused by mechanical ball milling impact, but also enable the additives during stirring and smelting to be evenly dispersed in the matrix. Combining traditional powder metallurgy and stirring casting into one, giving full play to the technical advantages of both, greatly improving the preparation efficiency while ensuring the superior performance of the material;

[0022] The raw materials used in the invention are green and environmentally friendly, the process operation is simple, and the invention is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0025] Example 1

[0026] A method for preparing a high temperature ball-milled carbon nanotube modified aluminum-based composite material comprises the following steps:

[0027] Step 1: premix the carbon nanotubes and copper powder using a high-speed shearing machine at a rotation speed of 3000 r / min to form a preform of carbon nanotubes and copper with a carbon nanotube mass fraction of 5 wt.%.

[0028] Step 2: Place the carbon nanotube and copper preforms and the aluminum ingot in a ball mill, heat the ball mill at 700°C, and put in ball mill beads ten times the mass of the ball mill material, wherein the carbon nanotube and copper preforms account for 2wt.% of the total mass of the carbon nanotube and copper preforms and the aluminum ingot.

[0029] Step 3: The carbon nanotube and copper preform, aluminum ingot and ball milling beads are ball milled in a ball mill at a speed of 1000 r / min for 3 hours. After the ball milling, the ball milling product is filtered at a temperature of 600° C. to screen out the ball milling beads to obtain a ground carbon nanotube modified aluminum-based composite material.

[0030] Example 2

[0031] The preparation was carried out according to the steps of Example 1, except that the rotation speed of the high-speed shearing machine in Step 1 was 1000 r / min.

[0032] Example 3

[0033] The preparation was carried out according to the steps of Example 1, except that the rotation speed of the high-speed shearing machine in Step 1 was 2000 r / min.

[0034] Example 4

[0035] The preparation was carried out according to the steps of Example 1, except that the rotation speed of the high-speed shearing machine in Step 1 was 4000 r / min.

[0036] Example 5

[0037] The preparation was carried out according to the steps of Example 1. The difference from Example 1 is that the mass percentage of the carbon nanotubes in the step 1 to the preform of the carbon nanotubes and copper is 1 wt.%.

[0038] Example 6

[0039] The preparation was carried out according to the steps of Example 1. The difference from Example 1 is that the mass percentage of the carbon nanotubes in the step 1 to the preform of the carbon nanotubes and copper is 10 wt.%.

[0040] Example 7

[0041] The preparation was carried out according to the steps of Example 1. The difference from Example 1 is that the mass percentage of the carbon nanotubes in the step 1 to the preform of the carbon nanotubes and copper is 15 wt.%.

[0042] Example 8

[0043] The preparation was carried out according to the steps of Example 1, but the difference from Example 1 was that the carbon nanotube and copper preform in step 2 accounted for 1 wt.% of the total mass of the carbon nanotube and copper preform and the aluminum ingot.

[0044] Example 9

[0045] The preparation was carried out according to the steps of Example 1, but the difference from Example 1 was that the carbon nanotube and copper preform in step 2 accounted for 3 wt.% of the total mass of the carbon nanotube and copper preform and the aluminum ingot.

[0046] Example 10

[0047] The preparation was carried out according to the steps of Example 1, but the difference from Example 1 was that the carbon nanotube and copper preform in step 2 accounted for 4 wt.% of the total mass of the carbon nanotube and copper preform and the aluminum ingot.

[0048] Embodiment 11

[0049] The preparation was carried out according to the steps of Example 1, except that the heating temperature of the ball mill in Step 2 was 500°C.

[0050] Example 12

[0051] The preparation was carried out according to the steps of Example 1, except that the heating temperature of the ball mill in step 2 was 600°C.

[0052] Example 13

[0053] The preparation was carried out according to the steps of Example 1, except that the heating temperature of the ball mill in Step 2 was 800°C.

[0054] Embodiment 14

[0055] The preparation was carried out according to the steps of Example 1, except that the rotation speed of the ball mill in step 3 was 100 r / min.

[0056] Embodiment 15

[0057] The preparation was carried out according to the steps of Example 1, except that the rotation speed of the ball mill in step 3 was 500 r / min.

[0058] Example 16

[0059] The preparation was carried out according to the steps of Example 1, except that the rotation speed of the ball mill in step 3 was 1500 r / min.

[0060] Embodiment 17

[0061] The preparation was carried out according to the steps of Example 1, except that the ball milling time in step 3 was 0.5 h.

[0062] Embodiment 18

[0063] The preparation was carried out according to the steps of Example 1, except that the ball milling time in step 3 was 6 h.

[0064] Embodiment 19

[0065] The preparation was carried out according to the steps of Example 1, except that the ball milling time in step 3 was 9 hours.

[0066] The tensile strength and elongation of the carbon nanotube reinforced aluminum-based composite materials prepared in Examples 1 to 19 were tested. The test results are shown in Table 1.

[0067] Table 1 Comparison of mechanical properties of Examples 1 to 19

[0068] sample Axial tensile strength MPa Axial elongation (%) Example 1 585 7.1 Example 2 432 7.2 Example 3 514 8.1 Example 4 532 8.0 Example 5 539 7.8 Example 6 552 7.1 Example 7 473 7.2 Example 8 489 8.1 Example 9 555 8.0 Example 10 538 7.8 Embodiment 11 528 7.5 Example 12 514 7.3 Example 13 473 6.9 Embodiment 14 489 7.5 Embodiment 15 546 7.3 Example 16 575 7.1 Embodiment 17 523 7.2 Embodiment 18 546 7.3 Embodiment 19 549 7.5

[0069] It can be seen from the data in Table 1 that an orthogonal test was conducted on six process parameters, including the rotation speed of the high-speed shearing machine, the mass percentage of carbon nanotubes in the carbon nanotube-copper preform, the total mass ratio of carbon nanotube-copper preform to preform-aluminum ingot, the heating temperature of the ball mill, the rotation speed of the ball mill, and the ball milling time. After mechanical property testing, the rotation speed of the high-speed shearing machine used in Example 1 is 3000r / min, the mass percentage of carbon nanotubes in the carbon nanotube-copper preform is 5wt.%, the total mass ratio of carbon nanotube-copper preform to preform-aluminum ingot is 2wt.%, the heating temperature of the ball mill is 700°C, the rotation speed of the ball mill is 1000r / min, and the ball milling time is 3h as the optimal process parameters. The tensile strength of the prepared aluminum-based composite material reaches 585MPa and the elongation reaches 7.1%.

[0070] The raw materials and equipment used in the present invention, unless otherwise specified, are all commonly used raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are all conventional methods in the art.

[0071] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a high temperature ball-milled carbon nanotube modified aluminum-based composite material, characterized in that: It includes the following steps: Step 1: premixing carbon nanotubes and copper powder to form a preform of carbon nanotubes and copper; Step 2: placing the carbon nanotube and copper preforms and the aluminum ingot in a ball mill, heating the ball mill, and placing ball mill beads; Step 3: ball-milling the carbon nanotube and copper preform, the aluminum ingot and the ball-milling beads in a ball-milling tank at a preset speed for a preset time, filtering the ball-milling product under a preset temperature environment after the ball-milling, screening out the ball-milling beads, and obtaining a ground carbon nanotube modified aluminum-based composite material; In the step 1, the carbon nanotubes and the copper powder are pre-mixed by a high-speed shearing machine, and the speed of the high-speed shearing machine is 1000-5000 r / min; In step 2, the ball mill is heated at a temperature of 500 to 800°C.

2. The method for preparing a high temperature ball-milled carbon nanotube-modified aluminum-based composite material according to claim 1, characterized in that: In the step 1, the mass percentage of the carbon nanotubes to the preform of the carbon nanotubes and copper is 1 to 20 wt.%.

3. The method for preparing a high temperature ball-milled carbon nanotube-modified aluminum-based composite material according to claim 1, characterized in that: In step 2, the carbon nanotube and copper preform accounts for 1-10 wt.% of the total mass of the carbon nanotube and copper preform and the aluminum ingot.

4. The method for preparing a high temperature ball-milled carbon nanotube-modified aluminum-based composite material according to claim 1, characterized in that: In the step 2, the mass of the ball milling beads is 9 to 11 times that of the ball milling material.

5. The method for preparing a high temperature ball-milled carbon nanotube-modified aluminum-based composite material according to claim 1, characterized in that: In step 3, the rotation speed of the ball milling treatment in the ball milling jar is 100 to 2000 r / min.

6. The method for preparing a high temperature ball-milled carbon nanotube modified aluminum-based composite material according to claim 1, characterized in that: In step 3, the ball milling time in the ball mill is 0.5 to 10 hours.

7. The method for preparing a high temperature ball-milled carbon nanotube-modified aluminum-based composite material according to claim 1, characterized in that: In the step 3, after the ball milling is completed, the ball milling product is filtered at a temperature of 500 to 800°C.

8. The method for preparing a high temperature ball-milled carbon nanotube-modified aluminum-based composite material according to claim 1, characterized in that: In the step 3, after the ball milling is completed, the ball milling product is filtered using a filter screen made of a wire mesh.

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