CN108118174B - Preparation method of carbon nano tube reinforced copper-based composite material - Google Patents

Abstract

The invention discloses a preparation method of a carbon nanotube reinforced copper-based composite material. By adding MWCNTs evenly between copper foils, through SPS sintering and cold rolling processes, a layered MWCNTs/Cu composite material thin strip is obtained. The relative density of the obtained MWCNTs/Cu composite material is 94.3-98.6%. Compared with the traditional powder SPS sintered MWCNTs/Cu composite, the resistivity is reduced by 10%-16%, and the yield strength is comparable.

Description

A kind of preparation method of carbon nanotube reinforced copper matrix composite material

technical field

The invention relates to a preparation method of a carbon nanotube reinforced copper-based composite material, and belongs to the field of composite material preparation.

Background technique

With the rapid development of science and technology and social economy, the strength, hardness, wear resistance and thermal stability of traditional copper and its alloy materials are more and more difficult to meet the performance requirements of copper materials in many fields, thus promoting copper matrix composite materials. material development. As typical one-dimensional nanomaterials, CNTs have ultra-high aspect ratios, superior mechanical properties, high electrical conductivity, high thermal conductivity, and low thermal expansion coefficients, and are considered as ideal reinforcement phases for the preparation of high-performance composites. The powder metallurgy method is generally used to add CNTs to the metal matrix to improve the physical properties of the metal. However, due to the agglomeration of CNTs and the non-wettability with Cu, CNTs/Cu composites prepared by traditional powder metallurgy sintering often have problems such as uneven distribution of CNTs, unsatisfactory electrical conductivity and mechanical properties.

Compared with the traditional powder metallurgy method, the SPS sintering process has the characteristics of faster sintering and lower energy consumption. The faster sintering speed can reduce the agglomeration of CNTs during the sintering process. However, due to the limitations of SPS sintering itself, it is usually only used for powder sintering. However, in the process of preparing CNTs reinforced copper matrix composites by powder powder gold method, it is necessary to carry out ball milling and mixing, and the ball milling process often causes CNTs to be cut off, reducing its aspect ratio, and the density difference between CNTs and copper powder is large. The size difference is large, and it is difficult to ensure the uniformity of mixing CNTs and copper powder by ball milling and other methods, and improper setting of ball milling parameters may lead to cold welding between copper powders, which is not conducive to sintering, so even if SPS is used, it is difficult to obtain dense composites. At the same time, the agglomeration of CNTs cannot be completely avoided, both of which will affect the final properties of the composites, especially the electrical conductivity of the composites.

SUMMARY OF THE INVENTION

In view of the deficiencies of the prior art, the purpose of the present invention is to provide a preparation method of a carbon nanotube reinforced copper matrix composite material in which copper foil is used as a matrix and combined with SPS sintering and cold rolling processes to promote the uniform dispersion of MWCNTs in the copper matrix.

A preparation method of a carbon nanotube reinforced copper-based composite material of the present invention comprises the following steps:

(1) The suspension containing multi-walled carbon nanotubes (MWCNTs) is sprayed on the copper foil, and dried to obtain copper foil A containing MWCNTs on the surface, and the mass fraction of MWCNTs in copper foil A is controlled to be 0.2-1.0% ;

(2) Assemble the copper foil A layer by layer, place it in a spark plasma sintering (SPS) furnace, and sinter it in a vacuum atmosphere. , and cooled after sintering to obtain MWCNTs/Cu composite preforms;

(3) The MWCNTs/Cu composite material preform is subjected to multi-pass cold rolling and annealing treatment to obtain a carbon nanotube reinforced copper matrix composite material. , The annealing process between passes is 500～600℃×10min.

The present invention provides a method for preparing a carbon nanotube reinforced copper-based composite material. In step (1), the length of the MWCNTs is 10-30 μm, and the diameter is less than 8 nm.

The present invention is a preparation method of a carbon nanotube reinforced copper-based composite material. In step (1), the MWCNTs are first purified, and the purification process is as follows: placing in 7.0M concentrated nitric acid, stirring and heating at 120° C. After refluxing for 4-5 hours, the purified MWCNTs were obtained after dilution, suction filtration and drying.

The present invention is a preparation method of a carbon nanotube reinforced copper-based composite material. In step (1), the formation process of the suspension is to place the MWCNTs in anhydrous ethanol and process with the aid of ultrasonic waves, and the ultrasonic time is 2h.

The present invention provides a method for preparing a carbon nanotube reinforced copper-based composite material. In step (1), the copper foil has a thickness of 50 μm and a diameter of 40 mm, and the raw material of the copper foil is red copper.

The present invention provides a method for preparing a carbon nanotube reinforced copper-based composite material. In step (1), the mass fraction of MWCNTs in the copper foil A is controlled to be 0.2-0.8%.

The present invention provides a method for preparing a carbon nanotube reinforced copper-based composite material. In step (2), the number of layers used for the stacking of the copper foil A is 50 to 80 layers.

The present invention provides a method for preparing a carbon nanotube reinforced copper-based composite material. In step (2), the sintering temperature is 850-900° C., the sintering pressure is 20 Mpa, and the holding time is 5 minutes.

The present invention provides a method for preparing a carbon nanotube-reinforced copper-based composite material. In step (2), the heating rate during the sintering process is 40-50° C./min.

The present invention provides a method for preparing a carbon nanotube reinforced copper-based composite material. In step (2), the cooling method is to perform water cooling on a furnace, and the cooling rate during the cooling process is controlled to be 50-60°C/min.

The present invention provides a method for preparing a carbon nanotube reinforced copper-based composite material. In step (3), the number of times of the multi-pass cold rolling and annealing treatment is 5 times.

The present invention provides a method for preparing a carbon nanotube reinforced copper-based composite material. In step (3), the total reduction of the pass is 92% to 95%.

The present invention provides a method for preparing a carbon nanotube-reinforced copper-based composite material. In step (3), the thickness of the obtained carbon nanotube-reinforced copper-based composite material is 0.2 mm, and the volume ratio of MWCNTs in the composite material is 0.9-4.5% . In the present invention, the thickness of the carbon nanotube reinforced composite material is finally controlled to be 0.2 mm by the number of layers of copper foil and the total pressing amount in the cold rolling process.

The present invention provides a method for preparing a carbon nanotube-reinforced copper-based composite material. The carbon nanotube-reinforced copper-based composite material obtained in step (3) has a relative density of 94.3% to 98.6% and a resistivity of 0.212 (μΩ·m) to 0.0281. (μΩ·m), the hardness is 64HV to 73.5HV.

Beneficial effects of the present invention:

The invention uses copper foil as the matrix for the first time, and by spraying 0.2-1.0% MWCNTs on the surface of the copper foil, stacking 50-80 layers of copper foil, and cooperating with the control conditions in the sintering process of SPS, the surface containing MWCNTs is successfully realized. SPS sintering of copper foil, and through the control of multi-pass cold rolling and annealing process parameters, 0.2mm MWCNTs/Cu composites can be obtained in a controllable manner, and the volume ratio of MWCNTs in the composites is 0.9-4.5% , that is, a composite material with high MWCNTs content was obtained.

In the present invention, the size of the copper foil and the number of layers to be stacked are preferred. SPS is sintered first. After SPS sintering, the layers of the copper foil have been diffused before each other. At the same time, the diffusion of copper formed in the SPS sintering process restricts carbon. , so that the MWCNTs particles are confined in a small area, which is the same as the grid or approximate grid formed with copper, the MWCNTs are dispersed in the grid, and then use 5 times of cold rolling with a large total pressure of more than 90%. The amount of MWCNTs on the copper foil is further uniformly distributed in the small area of the grid, so that the MWCNTs are fully diluted and the possibility of agglomeration is completely avoided. Foil growth, so that a high volume fraction of MWCNTs content, uniform distribution, and high density composites can be obtained.

Using the present invention, taking the addition of 0.2% MWCNTs as an example, the relative density of the prepared carbon nanotube composite material reaches 98.6%, the resistivity in the parallel interlayer direction is 0.0212 (μΩ·m), and the hardness is 70.9HV.

To sum up, the carbon nanotube composite material and the preparation method thereof provided by the present invention can realize the uniform distribution of MWCNTs in the pure Cu matrix, and the obtained composite material has high density, which is compared with the traditional powder SPS sintered MWCNTs/Cu composite material. , the resistivity of the MWCNTs/Cu composite material obtained by the invention is reduced by 10% to 16%, and the hardness and yield strength are equivalent, indicating that the distribution of MWCNTs is more uniform and the electrical conductivity is improved, which can greatly broaden the application range of this type of material.

Description of drawings

1 is a flow chart of the preparation of the carbon nanotube composite material of the present invention.

Fig. 2 is a SEM image of the carbon nanotube composite material obtained in Example 2 of the present invention, wherein (a) is the distribution of MWCNTs after 2 passes of rolling, (b) is when 5 passes of rolling are carried out The distribution of MWCNTs.

Detailed ways

Example 1:

(1) Multi-walled carbon nanotubes (MWCNTs) with a length of 10-30 μm and a diameter of less than 8 nm were placed in 7.0 M concentrated nitric acid, heated under reflux at 120 °C for 4 h, diluted, filtered and dried to obtain purification (2) Disperse the purified MWCNTs in absolute ethanol and ultrasonically treat for 2 h to obtain an ink-like suspension; (3) Spray the MWCNTs suspension on a diameter of 40 mm and a thickness of 40 mm by spraying. On the copper foil of 50 μm, drying, and controlling the mass fraction of MWCNTs to be 0.2%; (4) 60 copper foils were assembled in layers, placed in a spark plasma sintering (SPS) furnace for sintering and forming, and the sintering temperature was 850 °C and the pressure was controlled at 850 °C. It is 20Mpa and the holding time is 5min; the heating rate during the sintering process is controlled to be 40℃/min. After the heat preservation is completed, the furnace is cooled by water cooling. (5) The sintered layered composite material is cold-rolled for 5 passes, the reduction of the pass is controlled to be less than 50%, the total reduction is 92%, and the annealing process between passes is 500 ° C × 10 min, and the thickness is prepared. The carbon nanotube composite material of the present invention is obtained as a thin strip of 0.2 mm. The relative density of the carbon nanotube composite material is 98.6%, the resistivity in the parallel interlayer direction is 0.0212 (μΩ·m), and the hardness is 70.9HV.

Example 2:

(1) Multi-walled carbon nanotubes (MWCNTs) with a length of 10-30 μm and a diameter of less than 8 nm were placed in 7.0 M concentrated nitric acid, heated under reflux at 120 °C for 4 h, diluted, filtered and dried to obtain purification (2) Disperse the purified MWCNTs in absolute ethanol and ultrasonically treat for 2 h to obtain an ink-like suspension; (3) Spray the MWCNTs suspension on a diameter of 40 mm and a thickness of 40 mm by spraying. 50 μm copper foil, dried, and the mass fraction of MWCNTs was controlled to be 0.4%; (4) 50 copper foils were assembled in layers, placed in a spark plasma sintering (SPS) furnace for sintering, and the sintering temperature was 850 °C and the pressure was controlled to be 0.4%. It is 20Mpa and the holding time is 5min; the heating rate during the sintering process is controlled to be 40℃/min. After the heat preservation is completed, the furnace is cooled by water cooling. (5) The sintered layered composite material is cold-rolled for 5 passes, the reduction of the pass is controlled to be less than 50%, the total reduction is 92%, and the annealing process between passes is 500 ° C × 10 min, and the thickness is prepared. The carbon nanotube composite material of the present invention is obtained as a thin strip of 0.2 mm. The relative density of the carbon nanotube composite material is 97.3%, the resistivity in the parallel interlayer direction is 0.0231 (μΩ·m), and the hardness is 64HV.

Example 3:

(1) Multi-walled carbon nanotubes (MWCNTs) with a length of 10-30 μm and a diameter of less than 8 nm were placed in 7.0 M concentrated nitric acid, heated under reflux at 120 °C for 4 h, diluted, filtered and dried to obtain purification (2) Disperse the purified MWCNTs in absolute ethanol and ultrasonically treat for 2 h to obtain an ink-like suspension; (3) Spray the MWCNTs suspension on a diameter of 40 mm and a thickness of 40 mm by spraying. 50 μm copper foil, dried, and the mass fraction of MWCNTs was controlled to be 0.6%; (4) 50 copper foils were assembled in layers, placed in a spark plasma sintering (SPS) furnace for sintering, and the sintering temperature was controlled to be 850 °C and the pressure was 850 °C. It is 20Mpa and the holding time is 5min; the heating rate during the sintering process is controlled to be 45°C/min. After the heat preservation is completed, the furnace is cooled by water cooling. (5) The sintered layered composite material is cold-rolled for 5 passes, the reduction of the pass is controlled to be less than 50%, the total reduction is 92%, and the annealing process between passes is 500 ° C × 10 min, and the thickness is prepared. The carbon nanotube composite material of the present invention is obtained as a thin strip of 0.2 mm. The relative density of the carbon nanotube composite material is 95.7%, the resistivity in the parallel interlayer direction is 0.0265 (μΩ·m), and the hardness is 70.3HV.

Example 4:

(1) Multi-walled carbon nanotubes (MWCNTs) with a length of 10-30 μm and a diameter of less than 8 nm were placed in 7.0 M concentrated nitric acid, heated under reflux at 120 °C for 4 h, diluted, filtered and dried to obtain purification (2) Disperse the purified MWCNTs in absolute ethanol and ultrasonically treat for 2 h to obtain an ink-like suspension; (3) Spray the MWCNTs suspension on a diameter of 40 mm and a thickness of 40 mm by spraying. 50μm copper foil, dried, and the mass fraction of MWCNTs was controlled to be 0.8%; (4) 60 copper foils were laminated and assembled, placed in a spark plasma sintering (SPS) furnace for sintering and forming, and the sintering temperature was 900 °C and the pressure was controlled to be 900 °C. It is 25Mpa and the holding time is 5min; the heating rate during the sintering process is controlled to be 45℃/min. After the heat preservation is completed, the furnace is cooled by water cooling. (5) The sintered layered composite material is cold-rolled for 5 passes, and the pass reduction is controlled to be less than 50%, the total reduction is 93.3%, and the annealing process between passes is 600 ℃ × 10min, and the thickness is prepared. The carbon nanotube composite material of the present invention is obtained as a thin strip of 0.2 mm. The relative density of the carbon nanotube composite material is 95.1%, the resistivity in the parallel interlayer direction is 0.0275 (μΩ·m), and the hardness is 72.3HV.

Example 5:

(1) Multi-walled carbon nanotubes (MWCNTs) with a length of 10-30 μm and a diameter of less than 8 nm were placed in 7.0 M concentrated nitric acid, heated under reflux at 120 °C for 4 h, diluted, filtered and dried to obtain purification (2) Disperse the purified MWCNTs in absolute ethanol and ultrasonically treat for 2 h to obtain an ink-like suspension; (3) Spray the MWCNTs suspension on a diameter of 40 mm and a thickness of 40 mm by spraying. On the copper foil of 50 μm, drying, and controlling the mass fraction of MWCNTs to be 0.8%; (4) Assembling the copper foil 80 layers in layers, placing it in a spark plasma sintering (SPS) furnace for sintering and forming, and controlling the sintering temperature to be 900 °C and the pressure to be 900 °C. The temperature is 25Mpa and the holding time is 5min; the heating rate during the sintering process is controlled to be 50℃/min. After the heat preservation is completed, the furnace is cooled by water cooling. (5) The sintered layered composite material is cold-rolled for 5 passes, the reduction of the pass is controlled to be less than 50%, the total reduction is 95%, and the annealing process between passes is 600 ° C × 10 min, and the thickness is prepared. The carbon nanotube composite material of the present invention is obtained as a thin strip of 0.2 mm. The relative density of the carbon nanotube composite material is 94.3%, the resistivity in the parallel interlayer direction is 0.0281 (μΩ·m), and the hardness is 73.5HV.

Comparative Example 1

The remaining conditions are the same as in Example 1, except that the temperature is adjusted to 600°C. After SPS sintering, it is found that the copper foils are not sintered together.

Comparative Example 2

The rest of the conditions are the same as in Example 3, except that the temperature is adjusted to 750°C. After SPS sintering, it is found that the copper foils are not sintered together.

Comparative Example 3

The rest of the conditions were the same as in Example 1, except that the temperature was adjusted to 950°C, and the copper foil occasionally melted. The copper foil is melted and a liquid phase is generated, causing the carbon nanotubes to agglomerate in the liquid phase, which seriously affects their dispersion uniformity.

Comparative Example 4

(1) Multi-walled carbon nanotubes (MWCNTs) with a length of 10-30 μm and a diameter of less than 8 nm were placed in 7.0 M concentrated nitric acid, heated under reflux at 120 °C for 4 h, diluted, filtered and dried to obtain purification (2) Disperse the purified MWCNTs in absolute ethanol and ultrasonically treat for 2 h to obtain an ink-like suspension; (3) Spray the MWCNTs suspension on a diameter of 40 mm and a thickness of 40 mm by spraying. 50μm copper foil, dried, and the mass fraction of MWCNTs was controlled to be 1.4%; (4) 50 copper foils were assembled in layers, placed in a spark plasma sintering (SPS) furnace for sintering, and the sintering temperature was controlled at 850°C and the pressure was 850°C. It is 20Mpa, and the holding time is 5min. After sintering, it was found that the copper foils were delaminated, which indicated that the sintering of copper foils was difficult due to too many MWCNTs between layers.

Comparative Example 5

The rest of the conditions were the same as in Example 1, only the SPS and the cold rolling process were exchanged, and it was found that the copper foils were delaminated, and no bond could be formed. This is because the content of multi-layer graphene added in Example 1 is 0.2%, which is equivalent to theoretically obtaining a composite material with a graphene volume ratio of 0.9%. For such a high volume composite, it is impossible to cold-roll first obtained after sintering.

Comparative Example 6

The rest of the conditions are the same as in Example 5, except that the pass reduction is changed to 60%, and it is found that the copper foil is cracked during the cold rolling process.

Claims (9)

1. A preparation method of a carbon nano tube reinforced copper-based composite material is characterized by comprising the following steps: the method comprises the following steps:

(1) spraying the suspension containing the MWCNTs on a copper foil, and drying to obtain a copper foil A with the surface containing the MWCNTs, wherein the mass fraction of the MWCNTs in the copper foil A is controlled to be 0.2-1.0%;

(2) assembling the A layer of the copper foil in a laminated manner, placing the copper foil in an SPS furnace, sintering and forming in a vacuum atmosphere, controlling the sintering temperature to be 800-900 ℃, the sintering pressure to be 20-25 Mpa and the heat preservation time to be 5-10 min, and cooling after sintering to obtain an MWCNTs/Cu composite material prefabricated part; the number of layers for assembling the copper foil A laminated layer is 50-80;

(3) and (2) carrying out multi-pass cold rolling and annealing treatment on the MWCNTs/Cu composite material prefabricated member to obtain the carbon nano tube reinforced copper-based composite material, wherein the pass reduction is less than 50%, the total reduction is more than 90%, and the inter-pass annealing process is 500-600 ℃ multiplied by 10 min.

2. The method for preparing a carbon nanotube reinforced copper-based composite material according to claim 1, wherein the method comprises the following steps: in the step (1), the MWCNTs have the length of 10-30 mu m and the pipe diameter of less than 8 nm.

3. The method for preparing a carbon nanotube reinforced copper-based composite material according to claim 1, wherein the method comprises the following steps: in the step (1), the MWCNTs are firstly purified, and the purification process comprises the following steps: and (3) placing the mixture into concentrated nitric acid of 7.0M, stirring and heating the mixture at 120 ℃ for refluxing for 4-5 h, diluting, filtering, and drying to obtain the purified MWCNTs.

4. The method for preparing a carbon nanotube reinforced copper-based composite material according to claim 1, wherein the method comprises the following steps: in the step (1), the MWCNTs are placed in absolute ethyl alcohol and treated under the assistance of ultrasonic waves, and the ultrasonic time is 2 hours.

5. The method for preparing a carbon nanotube reinforced copper-based composite material according to claim 1, wherein the method comprises the following steps: in the step (1), the copper foil is 50 μm thick and 40mm in diameter, and the copper foil is made of red copper.

6. The method for preparing a carbon nanotube reinforced copper-based composite material according to claim 1, wherein the method comprises the following steps: in the step (1), the mass fraction of MWCNTs in the copper foil A is controlled to be 0.2-0.8%.

7. The method for preparing a carbon nanotube reinforced copper-based composite material according to claim 1, wherein the method comprises the following steps: in the step (2), the sintering temperature is 850-900 ℃,

in the step (2), the temperature rise rate in the sintering process is 40-50 ℃/min.

8. The method for preparing a carbon nanotube reinforced copper-based composite material according to claim 1, wherein the method comprises the following steps: in the step (3), the times of the multi-pass cold rolling and annealing treatment are 5 times, and the total reduction of the passes is 92-95%.

9. The method for preparing a carbon nanotube-reinforced copper-based composite material according to any one of claims 1 to 8, wherein: the carbon nano tube reinforced copper-based composite material obtained in the step (3) has the relative density of 94.3-98.6%, the resistivity of 0.212 (mu omega-m) to 0.0281 (mu omega-m) and the hardness of 64 HV-73.5 HV.

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