CN115780801A - Preparation method of ball-milled carbon nanotube modified aluminum-based composite material at high temperature - Google Patents

Abstract

The invention discloses a method for preparing aluminum-based composite materials modified by grinding carbon nanotubes, which is characterized in that it comprises the following steps: Step 1: pre-mixing carbon nanotubes and copper powder to form carbon nanotubes and copper powder Prefabricated body; Step 2: Place the prefabricated body of carbon nanotubes and copper and aluminum ingots in a ball milling jar, heat the ball milling jar, and put ball milling beads; Step 3: Put the carbon nanotubes in the ball milling jar at a preset speed The tube and copper prefabricated body, aluminum ingot and ball milling beads are ball milled for a preset time. After the ball milling, the ball milling product is filtered under a preset temperature environment, and the ball milling beads are screened out to obtain a milled carbon nanotube modified aluminum matrix composite. Material. Combining traditional powder metallurgy and stirring casting into one, the production efficiency is greatly improved, and it has high practical production guiding significance.

Description

A kind of preparation method of ball milling carbon nanotube modified aluminum matrix composite material under high temperature

technical field

The invention relates to the technical field of aluminum alloy preparation, in particular to a method for preparing a ball-milled carbon nanotube modified aluminum-based composite material at high temperature.

Background technique

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

The Chinese patent document with publication number CN109020590B discloses a method for preparing carbon nanotube-reinforced alumina-based composite materials by spray pyrolysis and hot pressing, which belongs to the technical field of composite material preparation. In this invention, pretreated carbon nanotubes and sodium lauryl sulfate are added to deionized water to prepare a carbon nanotube dispersion, aluminum nitrate is added to prepare a carbon nanotube/aluminum salt solution, and carbon nanotubes are generated by adding ammonia water. Nanotube/aluminum hydroxide sol, atomize carbon nanotube/aluminum hydroxide sol into small droplets, evaporate the water in the droplets in a short time through a pyrolysis furnace, and decompose aluminum hydroxide into amorphous alumina At the same time, the uniformly dispersed carbon nanotubes in the coating droplets are obtained to obtain spherical particles of amorphous alumina-coated carbon nanotubes with a relatively uniform particle size, and the spherical powder is sintered by hot pressing to form a carbon nanotube-reinforced alumina-based composite material. However, this method is complicated in process and is not suitable for mass production. The Chinese patent document whose publication number is CN110938764B discloses a preparation method of a carbon nanotube/aluminum composite material with high mechanical strength and high conductivity, including the following steps: Step 1: take a single-walled carbon nanotube whose diameter is below 6nm, The etchant etches the cap end of the carbon nanotube 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, obtain a single-walled carbon nanotube with an aspect ratio of about 250. walled carbon nanotubes. By coating the surface of single-walled carbon nanotubes with a layer of boride or rare earth coating with excellent wettability to the aluminum matrix, the compatibility with the aluminum matrix is improved, and the distribution is uniform in the aluminum matrix. At the same time, high temperature annealing The treatment increases the diffusion of metal atoms among the carbon tubes, and these treatments effectively improve the overall mechanical properties and electrical conductivity of the carbon nanotube-aluminum composite. However, this method needs to use an etchant to etch the cap end of the carbon nanotube at high temperature, and the fault tolerance rate is low.

Therefore, there is still a lack of a simple and efficient method for preparing carbon nanotube-modified aluminum matrix composites.

Contents of the invention

The purpose of the present invention is to provide a method for preparing aluminum-based composite materials modified by ball-milling carbon nanotubes at high temperature. This method combines traditional powder metallurgy and stirring casting into one, shortens the process flow, greatly improves production efficiency, and has high practical production guiding significance.

To achieve this goal, the preparation method of the milled carbon nanotube modified aluminum-based composite material designed by the present invention comprises the following steps:

Step 1: Pre-mix carbon nanotubes and copper powder to form a preform of carbon nanotubes and copper. This design coats a layer of copper on the surface of carbon nanotubes to increase the wettability with the aluminum matrix;

Step 2: Put the prefabricated carbon nanotubes and copper and the aluminum ingot in the ball milling jar, heat the ball milling jar, and put in the ball milling beads. The above design adds a heating function to the ball milling jar of the traditional planetary ball mill, which can heat up to The temperature above the liquidus line of aluminum can melt aluminum;

Step 3: Carry out ball milling of carbon nanotubes and copper preforms, aluminum ingots and ball milling beads at a preset speed in a ball milling tank for a preset time, and filter the ball milling products under a preset temperature environment after the ball milling, Mill the beads to obtain the carbon nanotube modified aluminum-based composite material. The carbon nanotubes of the above design have also been dispersed evenly in the aluminum liquid. On the sieve made, the molten aluminum flows through the sieve, and the ball milling beads stay on the sieve, thereby achieving the filtering effect.

In step 1 of the above technical solution, carbon nanotubes and copper powder are premixed with a high-speed shearing machine, and the rotational speed of the high-speed shearing machine is 1000-5000 r/min. If the rotation speed is lower than 1000r/min, the carbon nanotubes will not be able to form a tight bond with the copper powder, and if the rotation speed is higher than 5000r/min, the structure of the carbon nanotubes will be destroyed.

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 be able to form an effective wetting layer.

In step 2 of the above technical solution, 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. 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.

In step 2 of the above technical solution, the heating temperature for heating the ball mill jar is 500-800°C. If the temperature is lower than 500°C, the molten aluminum will solidify, and if the temperature is higher than 800°C, the carbon nanotubes will be ablated.

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.

In step 3 of the above technical solution, the rotational speed of the ball milling treatment in the ball mill tank is 100-2000 r/min. If the rotation speed is lower than 100r/min, the carbon nanotubes will not be uniformly dispersed in the aluminum liquid, and if the rotation speed is higher than 2000r/min, the structure of the carbon nanotubes will be destroyed.

In step 3 of the above technical solution, the time for ball milling in the ball mill tank is 0.5-10 hours.

In step 3 of the above technical solution, after the ball milling is completed, the ball milling product is filtered under a temperature environment of 500-800°C. If the temperature is lower than 500°C, the molten aluminum will solidify, and if the temperature is higher than 800°C, the carbon nanotubes will be ablated.

In step 3 of the above technical solution, after the ball milling is completed, the ball milling product is filtered through a filter sieve made of steel wire mesh. Ablation and the introduction of impurities may occur with other screens.

Beneficial effects of the present invention:

The present invention improves the interfacial bonding between carbon nanotubes and aluminum liquid through the pre-combination of copper powder and carbon nanotubes;

At present, the industry needs to first prepare the preform by powder metallurgy, and then use high-temperature smelting to integrate the preform after powder metallurgy into the matrix material. The invention is equivalent to ball milling while smelting, which can not only reduce the structural damage of carbon nanotubes caused by the impact of mechanical ball milling by using the resistance of aluminum liquid, but also enable the additives during stirring and smelting to be uniformly dispersed in the matrix. Combine traditional powder metallurgy and stirring casting into one, give full play to the technical advantages of the two, and ensure the superior performance of the material while greatly improving the production efficiency;

The raw materials used in the invention are green and environment-friendly, the process is simple and easy to operate, and is suitable for mass industrial production.

Description of drawings

Fig. 1 is a process flow diagram of the present invention.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment the present invention is described in further detail:

Example 1

A method for preparing a ball-milled carbon nanotube modified aluminum-based composite material at high temperature, comprising the following steps:

Step 1: Pre-mixing carbon nanotubes and copper powder with a high-speed shearing machine at a speed of 3000 r/min to form a carbon nanotube and copper preform with a mass fraction of carbon nanotubes of 5 wt.%.

Step 2: Put the prefabricated body of carbon nanotubes and copper and the aluminum ingot in a ball milling jar, heat the ball milling jar at 700°C, and put ball milling beads ten times the mass of the ball milling material, the carbon nanotubes and copper The preform accounts for 2wt.% of the total mass of the carbon nanotube and copper preform and the aluminum ingot.

Step 3: Mill the preforms of carbon nanotubes and copper, aluminum ingots and ball milling beads in a ball milling tank at a speed of 1000 r/min for 3 hours. After the ball milling, filter the ball milling products at a temperature of 600° C. and sieve out the ball milling Beads were milled to obtain carbon nanotube-modified aluminum matrix composites.

Example 2

Prepared according to the steps of Example 1, the difference from Example 1 is that the speed of the high-speed shearing machine in the step 1 is 1000r/min.

Example 3

Prepared according to the steps of Example 1, the difference from Example 1 is that the speed of the high-speed shearing machine in the step 1 is 2000r/min.

Example 4

Prepared according to the steps of Example 1, the difference from Example 1 is that the speed of the high-speed shearing machine in the step 1 is 4000r/min.

Example 5

Prepared 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 in the preform of carbon nanotubes and copper is 1wt.%.

Example 6

Prepared 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 in the carbon nanotube and copper preform is 10wt.%.

Example 7

Prepared 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 in the carbon nanotube and copper preform is 15wt.%.

Example 8

Prepared according to the steps of Example 1, the difference from Example 1 is that the preform of carbon nanotubes and copper in the step 2 accounts for 1wt.% of the total mass of the preforms of carbon nanotubes and copper and the aluminum ingot.

Example 9

Prepared according to the steps of Example 1, the difference from Example 1 is that the preform of carbon nanotubes and copper in the step 2 accounts for 3wt.% of the total mass of the preforms of carbon nanotubes and copper and the aluminum ingot.

Example 10

Prepared according to the steps of Example 1, the difference from Example 1 is that the preform of carbon nanotubes and copper in the step 2 accounts for 4wt.% of the total mass of the preforms of carbon nanotubes and copper and the aluminum ingot.

Example 11

Prepared according to the steps of Example 1, the difference from Example 1 is that the heating temperature of the ball mill jar in the step 2 is 500°C.

Example 12

Prepared according to the steps of Example 1, the difference from Example 1 is that the heating temperature of the ball mill jar in the step 2 is 600°C.

Example 13

Prepared according to the steps of Example 1, the difference from Example 1 is that the heating temperature of the ball mill jar in the step 2 is 800°C.

Example 14

Prepared according to the steps of Example 1, the difference from Example 1 is that the rotating speed of the ball mill in Step 3 is 100r/min.

Example 15

Prepared according to the steps of Example 1, the difference from Example 1 is that the rotating speed of the ball mill in Step 3 is 500r/min.

Example 16

Prepared according to the steps of Example 1, the difference from Example 1 is that the rotating speed of the ball mill in Step 3 is 1500r/min.

Example 17

Prepared according to the steps of Example 1, the difference from Example 1 is that the time of the ball milling in the step 3 is 0.5h.

Example 18

Prepared according to the steps of Example 1, the difference from Example 1 is that the time of the ball milling in the step 3 is 6h.

Example 19

Prepared according to the steps of Example 1, the difference from Example 1 is that the time of the ball milling in the step 3 is 9h.

The tensile strength and elongation of the carbon nanotube-reinforced aluminum matrix composites prepared in Examples 1-19 were tested, and the test results are shown in Table 1.

The mechanical property contrast of table 1 embodiment 1～19

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 Example 11 528 7.5 Example 12 514 7.3 Example 13 473 6.9 Example 14 489 7.5 Example 15 546 7.3 Example 16 575 7.1 Example 17 523 7.2 Example 18 546 7.3 Example 19 549 7.5

As can be seen from the data in Table 1, from the rotating speed of the high-speed shearing machine, the mass percentage of carbon nanotubes to the carbon nanotube-copper preform, the carbon nanotube-copper preform to the total mass ratio of the preform to the aluminum ingot, Orthogonal experiments were carried out on 6 process parameters such as the heating temperature of the ball milling tank, the rotating speed of the ball milling, and the time of the ball milling. Through the mechanical performance test, the rotating speed of the high-speed shearing machine adopted in Example 1 was 3000r/min, and the carbon nanotube accounted for The mass percent of the carbon nanotube-copper preform is 5wt.%, the carbon nanotube-copper preform accounts for 2wt.% of the total mass ratio of the preform-aluminum ingot, the heating temperature of the ball mill jar is 700°C, and the ball milling speed is 1000r/min, ball milling time 3h as the optimal process parameters, the tensile strength of the prepared aluminum matrix composite material reaches 585MPa, and the elongation rate reaches 7.1%.

Raw materials used in the present invention, equipment, if not specified, are commonly used raw materials, equipment in this area; Method used in the present invention, if not specified, are conventional methods in this area.

The above are only preferred embodiments of the present invention, and do not limit the present invention in any way. All simple modifications, changes and equivalent transformations made to the above embodiments according to the technical essence of the present invention still belong to the technical solution of the present invention. scope of protection.

Claims (10)

1. A preparation method of a ball-milled carbon nanotube modified aluminum matrix composite material at a high temperature is characterized by comprising the following steps:

step 1: premixing the carbon nano tube and copper powder to form a prefabricated body of the carbon nano tube and the copper;

step 2: placing the prefabricated body of the carbon nano tube and the copper and an aluminum ingot into a ball milling tank, heating the ball milling tank, and placing ball milling beads into the ball milling tank;

and step 3: and (3) carrying out ball milling on the prefabricated body of the carbon nano tube and the copper, the aluminum ingot and the ball milling beads in a ball milling tank for a preset time at a preset rotating speed, filtering a ball milling product in a preset temperature environment after the ball milling is finished, and screening out the ball milling beads to obtain the carbon nano tube milled modified aluminum-based composite material.

2. The method for preparing the ball-milled carbon nanotube modified aluminum matrix composite material at the high temperature according to claim 1, which is characterized in that: in the step 1, the carbon nano tubes and the copper powder are premixed by a high-speed shearing machine, and the rotating speed of the high-speed shearing machine is 1000-5000 r/min.

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

4. The method for preparing the ball-milled carbon nanotube modified aluminum matrix composite material at the high temperature according to claim 1, which is 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.

5. The method for preparing a ball-milled carbon nanotube modified aluminum-based composite material at a high temperature according to claim 1, which is characterized in that: in the step 2, the heating temperature for heating the ball milling tank is 500-800 ℃.

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

7. The method for preparing the ball-milled carbon nanotube modified aluminum matrix composite material at the high temperature according to claim 1, which is characterized in that: in the step 3, the rotating speed of the ball milling treatment in the ball milling tank is 100-2000 r/min.

8. The method for preparing the ball-milled carbon nanotube modified aluminum matrix composite material at the high temperature according to claim 1, which is characterized in that: in the step 3, the ball milling treatment time in the ball milling tank is 0.5-10 h.

9. The method for preparing a ball-milled carbon nanotube modified aluminum-based composite material at a high temperature according to claim 1, which is characterized in that: in the step 3, after the ball milling is finished, filtering the ball milling product at the temperature of 500-800 ℃.

10. The method for preparing the ball-milled carbon nanotube modified aluminum matrix composite material at the high temperature according to claim 1, which is characterized in that: and in the step 3, filtering the ball-milled product by using a filter sieve made of a steel wire mesh after the ball milling is finished.

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