CN103128284B - Reinforced method of carbon nanotubes (CNTs) of laser-induced composite fused deposition gradient content for copper matrix composite materials - Google Patents

Abstract

The invention discloses a reinforced method of carbon nanotubes (CNTs) of laser-induced composite fused deposition gradient content for copper matrix composite materials. The reinforced method of CNTs of the laser-induced composite fused deposition gradient content for the copper matrix composite materials is characterized by comprising the following steps: screening the CNTs by means of a method of rotating electrophoreses, and obtaining the CNTs of the same diameters and the same lengths; increasing the CNTs obtained by screening in a gradient mode by mass percent, and mixing the CNTs with copper alloy powder to be uniform on a planetary ball mill, conducting chemical nickel-plating processing, and preparing copper matrix composite powder with CNTs diffuse distributed; preparing reinforced copper matrix composite materials of CNTs of the gradient content by means of a method of laser-induced composite fused deposition. The reinforced method of CNTs of the laser-induced composite fused deposition gradient content for the copper matrix composite materials has the advantages that the defects that the CNTs are easy to gather, hard to disperse and hard to sift are overcome due to the fact that the CNTs are obtained by means of the method of rotating electrophoreses; gradient distribution of the content of the CNTs in the copper matrix composite materials can be achieved under the condition of increasing fused cladding efficiency by 5 times - 15 times; the method is a near net shape rapid manufacturing technology, precious materials can be markedly saved, manufacture cost is lowered, and manufacturing cycle is shortened.

Description

Method of Laser-Induction Hybrid Melting Deposition Gradient Content CNTs Reinforced Copper Matrix Composites

technical field

The invention belongs to the field of rapid manufacturing technology, and in particular relates to a method for laser-induction compound melting deposition of CNTs with gradient content to strengthen copper-based composite materials.

Background technique

Copper alloy has excellent electrical conductivity, thermal conductivity, corrosion resistance and good processing performance, and has a wide range of applications in the fields of integrated circuit lead frames, high-speed iron contact wires, and continuous casting molds. However, copper alloys are insufficient in strength, high temperature softening temperature and wear resistance, which greatly limits their application in industrial fields. As we all know, there is a contradictory relationship between the high strength and high conductivity of copper alloys. Therefore, how to greatly improve the strength, hardness, wear resistance and corrosion resistance of copper alloys on the premise of reducing the electrical and thermal conductivity of copper alloys as little as possible is the goal pursued by researchers at home and abroad.

At present, alloying method or second phase particle reinforcement method is usually used to improve the strength of copper alloy. According to the conduction theory, the point Chen distortion caused by atoms dissolved in the copper matrix has a much stronger scattering effect on electrons than the second phase particles on electron scattering. Therefore, the second-phase particle-reinforced copper alloy will not significantly reduce the electrical and thermal conductivity of the copper alloy, and can improve the room temperature and high temperature properties of the copper alloy, which has become an effective method to increase the strength of the copper alloy. Especially since Japan's Iijima first observed carbon nanotubes with a high-resolution electron microscope (Iijima S. Helical microtubules of graphitic carbon. Nature, 1991, 354: 56-58), carbon nanotubes have shown extraordinary properties with their unique structures. Strength, thermal conductivity, magnetoresistance and other properties, as a highly potential reinforcing phase, can form metal matrix composites with metals that have the characteristics of high strength, high modulus, high temperature resistance, small thermal expansion coefficient and strong thermal denaturation resistance. attracted extensive attention from researchers

In recent years, the methods for preparing CNTs-reinforced copper-based composites mainly include: powder metallurgy (Wang Sen. Preparation and research of carbon nanotube-reinforced copper-based composites, master's thesis, Lanzhou University, 2009, high-energy ball milling-high temperature sintering method (Cai Xiaolan, Jiang Taiwei, Chen Yaguang, Wang Kaijun. A preparation method of carbon nanotube-reinforced copper-based composite material. Chinese invention patent, publication number: CN102628115A), hot pressing method (Chen Haiying. Hot pressing method to prepare carbon nanotube/copper composite material Microstructure and performance research. Master's degree thesis, Harbin Institute of Technology, 2006), etc. The above three methods all exist in the preparation process: carbon nanotubes are easy to agglomerate, unevenly distributed, poor wettability with copper substrate, complex process, very difficult It is difficult to prepare large-volume carbon nanotube-reinforced copper-based composite materials, especially it is difficult to prepare copper-based composite materials with a gradient distribution of carbon nanotubes, and it is difficult to meet the needs of the industrial field for high-strength and high-conductivity copper alloys with gradient changes in performance. need.

Contents of the invention

The purpose of the present invention is to provide a method for laser-induction composite melting deposition of CNTs with gradient content to strengthen copper-based composite materials. The laser-induction composite melting deposition technology described in the present invention is a rapid manufacturing technology for manufacturing high-performance compact components formed by combining laser-induction composite cladding technology and rapid prototype manufacturing technology. In addition, the present invention adopts the method of spin electrophoresis to screen out the carbon nanotubes with the same diameter and the same length, and then the carbon nanotubes are gradually increased according to the mass percentage, respectively mixed with copper alloy powder through a ball mill, and formed after electroless nickel plating, which has good fluidity and is suitable for automatic Powder feeding, copper-based composite powder with dispersed distribution of CNTs, and finally multi-layer laser-induction composite melting deposition to prepare CNTs-reinforced copper-based composite materials with gradient distribution along the thickness direction of the material.

The present invention is achieved like this, and its method and steps are:

(1) Screening of carbon nanotubes: use spin electrophoresis to screen and obtain carbon nanotubes with the same diameter and length, specifically:

1) Using a mixture of 30-70% sulfuric acid and 40-80% nitric acid with a volume ratio of 1:1, pickling carbon nanotubes with a diameter of 2-100nm and a length of 5-100μm for 3-10h to obtain purified carbon nanotube;

2) Add the purified carbon nanotubes into a surface modification tank filled with a hexadecyltrimethylammonium bromide solution with a concentration of 0.5~2.0g/L and a temperature of 40~90℃, and disperse them under ultrasonic waves. Disperse on the device for 2~8h, so that the purified carbon nanotubes are positively charged after surface modification;

3) The upper electrode of the rotary electrophoresis device is connected to the negative pole of the power supply, and rotates along its central axis at a speed of 5-10 rpm. The lower surface is equipped with a permeable membrane made of polyamide, and the lower electrode is connected to the positive pole of the power supply. Select the voltage of the rotating electrophoresis device in the range of 10~30V and fix it. The carbon nanotubes with the same diameter and the same length move to the upper electrode under the action of the electric field force and are adsorbed on the surface of the permeable membrane;

4) Take the permeable membrane adsorbed with carbon nanotubes from the lower surface of the upper electrode, completely dissolve in a mixed solvent of phenol and glacial acetic acid with a volume ratio of 1:1, filter and wash with deionized water, and dry in vacuum for 2~4h ;

(2) Preparation of copper-based composite powder with dispersed distribution of CNTs: The carbon nanotubes obtained by screening are gradually increased in mass percentage and mixed with copper alloy powder on a planetary ball mill, and then electroless nickel plating is performed to prepare a flowable Good performance, suitable for automatic powder feeding, copper-based composite powder with dispersed distribution of CNTs;

(3) Preparation of CNTs-reinforced copper-based composites with gradient content: the prepared copper-based composite powder with dispersed distribution of CNTs is prepared by multi-layer laser-induction composite melting deposition method to prepare CNTs-reinforced copper-based composites with gradient content , the laser used is a cross-flow CO ₂ laser, and the induction heater used is an integrated modular high-frequency induction heater. The specific process parameters are: laser power 1~10kW, laser scanning speed 1~8m/min, spot diameter 0.5~5mm , Induction heating power 10~150kW, powder feeding rate 30~300g/min, spray angle 45~53°, lap rate 40~60%.

The CNTs described in the present invention are distributed in a gradient of 0.05-20wt% along the thickness direction of the material, and the content of the CNTs in the outermost layer is 20wt%.

In the present invention, when the step (1) is carried out, a rotary electrophoresis device is installed in the surface modification tank, the upper and lower electrodes of the rotary electrophoresis device are circular with a diameter of 100-500mm, and the lower electrode is located at the surface of the surface modification tank. bottom.

When the present invention is performing the step (2), the chemical composition of the copper alloy powder is: Zr 0.1~0.35wt%, Al 0.8~5wt%, Ni 0.1~0.25wt%, Y 0.01~0.025wt%, Hf 0.01 ~0.035wt%, the balance is Cu.

When carrying out the step (3) of the present invention, each time a layer is deposited, the laser-induction composite melting processing head is raised along the Z-axis by a distance equal to the thickness of the CAD two-dimensional sheet, and at the same time, refills the powder into the automatic powder feeder. Copper-based composite powder with dispersed distribution of CNTs, in which the content of CNTs in the composite powder is increased by 0.05~5wt% compared with the deposition of the previous layer, and then laser-induction composite melting deposition is carried out according to the scanning trajectory of the next layer, when all After the two-dimensional flakes are scanned, a three-dimensional CNTs-reinforced copper-based composite material with a gradient distribution is formed.

Compared with the existing technology, the advantages of the present invention are: (1) The carbon nanotubes used are screened by spin electrophoresis, have the characteristics of the same diameter and the same length, and overcome the problems of easy agglomeration, difficulty in dispersing and Difficult to screen; (2) The copper-based composite powder with dispersed distribution of CNTs has been treated with electroless nickel plating, which improves its high-temperature oxygen resistance and the wettability of CNTs and copper-based alloys; (3) can improve the cladding efficiency Under the conditions of 5~15 times, the copper base with high strength and high hardness, high wear resistance and high corrosion resistance, high electrical conductivity and high thermal conductivity, no pores and no cracks, and the content of CNTs is distributed along the thickness direction of the material is prepared. Composite materials; (4) It is a near net shape rapid manufacturing technology. The preparation of CNTs reinforced copper matrix composites with gradient content requires only a small amount of finishing or no processing, which can significantly save precious materials, reduce manufacturing costs and shorten the manufacturing cycle.

Detailed ways

Example 1

Laser-induction composite melting deposition was used to prepare CNTs-reinforced copper matrix composite parts with gradient content, in which CNTs were distributed in a gradient of 0.05-20wt% along the thickness of the material. The part was a hollow cylinder: the inner diameter and outer diameter were 80mm and 83mm, height 10.2mm, the thickness of the CAD two-dimensional slice obtained by slicing technology is 1.02mm, the content of CNTs in the first layer is 2wt%, and the content of CNTs in the latter layer is 2wt% higher than that in the previous layer , a total of 10 layers are deposited, and the specific implementation process is as follows:

(1) Screening of carbon nanotubes: use spin electrophoresis to screen and obtain carbon nanotubes with the same diameter and length, specifically:

1) Using a mixture of 35% sulfuric acid and 80% nitric acid at a volume ratio of 1:1, pickling carbon nanotubes with a diameter of 2-100 nm and a length of 5-100 μm for 4 hours to obtain purified carbon nanotubes;

2) Add the purified carbon nanotubes into a surface modification tank filled with a cetyltrimethylammonium bromide solution with a concentration of 0.8g/L and a temperature of 90°C, and disperse on an ultrasonic disperser for 3h , so that the purified carbon nanotubes are positively charged after surface modification;

3) The rotary electrophoresis device is installed in the surface modification tank. The upper and lower electrodes of the rotary electrophoresis device are circular with a diameter of 100 mm. The lower electrode is located at the bottom of the surface modification tank. The upper electrode is connected to the negative pole of the power supply. Rotate at a speed of 5 rpm, the lower surface is equipped with a permeable membrane made of polyamide, the lower electrode is connected to the positive electrode of the power supply, the voltage of the rotating electrophoresis device is selected to be 10V, and the carbon nanotubes with the same diameter and the same length are under the action of the electric field force The lower electrode moves upward and is adsorbed on the surface of the permeable membrane;

4) Take the permeable membrane adsorbed with carbon nanotubes from the lower surface of the upper electrode, completely dissolve in a mixed solvent of phenol and glacial acetic acid with a volume ratio of 1:1, filter and wash with deionized water, and dry in vacuum for 2 hours;

(2) Preparation of copper-based composite powder with dispersed distribution of CNTs: The carbon nanotubes obtained by screening are gradually increased in mass percentage and mixed with copper alloy powder on a planetary ball mill, and then electroless nickel plating is performed to prepare a flowable Copper-based composite powder with good performance, suitable for automatic powder feeding and dispersed distribution of CNTs. Among them, the chemical composition of copper alloy powder is Zr 0.15wt%, Al 0.8wt%, Ni 0.15wt%, Y 0.015wt%, Hf 0.015wt% , the balance is Cu;

(3) Preparation of CNTs-reinforced copper-based composites with gradient content: In the process of multi-layer laser-induction composite melting deposition, the laser used is a cross-flow CO ₂ laser, and the induction heater used is an integrated modular high-frequency Induction heater, the specific process parameters are: laser power 5kW, laser scanning speed 3m/min, spot diameter 1.5mm, induction heating power 60kW, powder feeding rate 120g/min, spray angle 45°, lap rate 40%; in addition, After each layer is deposited, the laser-induction composite melting processing head is raised 1.02mm along the Z axis, and at the same time, copper-based composite powder with dispersed distribution of CNTs is added to the automatic powder feeder. The content of CNTs in the composite powder is related to the deposition. One layer is increased by 2wt% compared with that of the next layer, and then the laser-induction composite melting deposition is carried out according to the scanning trajectory of the next layer. When all the two-dimensional thin slices are scanned, a three-dimensional CNTs-enhanced copper-based composite with a gradient distribution of content is formed. Material.

Example 2

Laser-induction compound melting deposition was used to prepare CNTs-reinforced copper-based composite parts with gradient content, in which CNTs were distributed in a gradient of 0.05-20wt% along the thickness of the material. The part was a hollow cylinder: the inner diameter and outer diameter were 120mm and 125mm, the height is 50.49mm, the thickness of the CAD two-dimensional slice obtained by slicing technology is 0.99mm, the content of CNTs in the first layer is 2wt%, and the content of CNTs in the latter layer is 0.36wt higher than that in the previous layer %, a total of 51 layers are deposited, and the specific implementation process is as follows:

(1) Screening of carbon nanotubes: use spin electrophoresis to screen and obtain carbon nanotubes with the same diameter and length, specifically:

1) Using a mixture of 50% sulfuric acid and 60% nitric acid with a volume ratio of 1:1, pickling carbon nanotubes with a diameter of 2-100 nm and a length of 5-100 μm for 6 hours to obtain purified carbon nanotubes;

2) Add the purified carbon nanotubes into a surface modification tank filled with cetyltrimethylammonium bromide solution at a concentration of 1.5g/L and a temperature of 70°C, and disperse on an ultrasonic disperser for 6h , so that the purified carbon nanotubes are positively charged after surface modification;

3) The rotary electrophoresis device is installed in the surface modification tank. The upper and lower electrodes of the rotary electrophoresis device are circular with a diameter of 300 mm. The lower electrode is located at the bottom of the surface modification tank. The upper electrode is connected to the negative pole of the power supply. Rotating at a speed of 7 rpm, the lower surface is equipped with a permeable membrane made of polyamide, the lower electrode is connected to the positive pole of the power supply, and the voltage of the rotating electrophoresis device is selected to be 20V. Carbon nanotubes with the same diameter and the same length are under the action of the electric field force The upward electrode moves and adsorbs on the surface of the permeable membrane;

4) Take the permeable membrane adsorbed with carbon nanotubes from the lower surface of the upper electrode, completely dissolve it in a mixed solvent of phenol and glacial acetic acid with a volume ratio of 1:1, filter and wash with deionized water, and dry in vacuum for 3 hours;

(2) Preparation of copper-based composite powder with dispersed distribution of CNTs: The carbon nanotubes obtained by screening are gradually increased in mass percentage and mixed with copper alloy powder on a planetary ball mill, and then electroless nickel plating is performed to prepare a flowable Copper-based composite powder with good performance, suitable for automatic powder feeding, and dispersed distribution of CNTs. Among them, the chemical composition of copper alloy powder is Zr 0.25wt%, Al 2.5wt%, Ni 0.2wt%, Y 0.02wt%, Hf 0.025wt% , the balance is Cu;

(3) Preparation of CNTs-reinforced copper-based composites with gradient content: In the process of multi-layer laser-induction composite melting deposition, the laser used is a cross-flow CO ₂ laser, and the induction heater used is an integrated modular high-frequency Induction heater, the specific process parameters are: laser power 7kW, laser scanning speed 5m/min, spot diameter 2.5mm, induction heating power 100kW, powder feeding rate 200g/min, spray angle 50°, lap rate 50%; in addition, After each layer is deposited, the laser-induction composite melting processing head is raised by 0.99 mm along the Z axis, and at the same time, copper-based composite powder with dispersed distribution of CNTs is added to the automatic powder feeder. The content of CNTs in the composite powder and the deposition 0.36wt% increase compared to the previous layer, and then follow the scanning trajectory of the next layer for laser-induction composite melting deposition. When all the two-dimensional thin slices are scanned, a three-dimensional CNTs reinforced copper with gradient distribution is formed. base composite material.

Example 3

Laser-induction compound melting deposition was used to prepare CNTs-reinforced copper matrix composite parts with gradient content, in which CNTs were distributed along the thickness of the material in a gradient of 0.05-20wt%. The part was a hollow cylinder: the inner diameter and outer diameter were 300mm and 310mm, the height is 102.01mm, the thickness of the CAD two-dimensional slice obtained by slicing technology is 1.01mm, the content of CNTs in the first layer is 1.0wt%, and the content of CNTs in the latter layer is 0.19% higher than that in the previous layer wt%, a total of 101 layers were deposited, the specific implementation process is as follows:

(1) Screening of carbon nanotubes: use spin electrophoresis to screen and obtain carbon nanotubes with the same diameter and length, specifically:

1) Using a mixture of 65% sulfuric acid and 40% nitric acid with a volume ratio of 1:1, pickling carbon nanotubes with a diameter of 2-100 nm and a length of 5-100 μm for 8 hours to obtain purified carbon nanotubes;

2) Add the purified carbon nanotubes into a surface modification tank filled with cetyltrimethylammonium bromide solution with a concentration of 2.0g/L and a temperature of 50°C, and disperse on an ultrasonic disperser for 8h , so that the purified carbon nanotubes are positively charged after surface modification;

3) The rotary electrophoresis device is installed in the surface modification tank. The upper and lower electrodes of the rotary electrophoresis device are circular with a diameter of 500 mm. The lower electrode is located at the bottom of the surface modification tank. The upper electrode is connected to the negative pole of the power supply. Rotate at a speed of 9 rpm, the lower surface is equipped with a permeable membrane made of polyamide, the lower electrode is connected to the positive pole of the power supply, and the voltage of the rotating electrophoresis device is selected to be 30V. Carbon nanotubes with the same diameter and the same length are under the action of the electric field force The upward electrode moves and adsorbs on the surface of the permeable membrane;

4) Take the permeable membrane adsorbed with carbon nanotubes from the lower surface of the upper electrode, completely dissolve it in a mixed solvent of phenol and glacial acetic acid with a volume ratio of 1:1, filter and wash with deionized water, and vacuum dry for 4 hours;

(2) Preparation of copper-based composite powder with dispersed distribution of CNTs: The carbon nanotubes obtained by screening are gradually increased in mass percentage and mixed with copper alloy powder on a planetary ball mill, and then electroless nickel plating is performed to prepare a flowable Copper-based composite powder with good performance, suitable for automatic powder feeding, and dispersed distribution of CNTs. Among them, the chemical composition of copper alloy powder is Zr 0.35wt%, Al 4.5wt%, Ni 0.25wt%, Y 0.025wt%, Hf 0.03wt% , the balance is Cu;

(3) Preparation of CNTs-reinforced copper-based composites with gradient content: In the process of multi-layer laser-induction composite melting deposition, the laser used is a cross-flow CO ₂ laser, and the induction heater used is an integrated modular high-frequency Induction heater, the specific process parameters are: laser power 10kW, laser scanning speed 5m/min, spot diameter 5mm, induction heating power 150kW, powder feeding rate 300g/min, spray angle 53°, lap rate 60%; in addition, each After depositing one layer, raise the laser-induction composite melting processing head by 1.01 mm along the Z axis, and at the same time re-add the copper-based composite powder with dispersed distribution of CNTs into the automatic powder feeder, and the content of CNTs in the composite powder is related to the deposition. One layer is increased by 0.19wt%, and then the laser-induction composite melting deposition is carried out according to the scanning trajectory of the next layer. When all the two-dimensional thin slices are scanned, a three-dimensional CNTs reinforced copper matrix with a gradient distribution is formed. composite material.

Claims (5)

1. the CNTs of laser-inductive composite melt sedimentation gradient content strengthens a method for Cu-base composites, and its method step is:

(1) screening of CNT: adopt the method screening of rotation electrophoresis to obtain the CNT of same diameter and equal length, be specially:

1) adopting 30 ~ 70% sulfuric acid of volume ratio 1:1 and the mixed liquor of 40 ~ 80% nitric acid, is that 2 ~ 100nm and length are CNT pickling 3 ~ 10h of 5 ~ 100 μ m to diameter, obtains the CNT of purifying;

2) CNT after purifying is joined to concentration is housed is that 0.5 ~ 2.0g/L and temperature are in the surface modification groove of softex kw solution of 40 ~ 90 DEG C, on ultrasonic disperser, disperse 2 ~ 8h, make the CNT after purifying positively charged after surface modification;

3) top electrode of rotation electrophoretic apparatus connects power cathode, be 5 ~ 10 revs/min of rotations along its central shaft taking speed, its lower surface is provided with the permeable membrane that material is polyamide, bottom electrode connects positive source, in the scope that is 10 ~ 30V at DC voltage, choose the voltage of rotation electrophoretic apparatus and fix, the CNT that diameter is identical and length is identical electrode movement upwards under the effect of electric field force, and be adsorbed on permeable membrane surface;

4) permeable membrane that absorption is had to a CNT from power on lower surface of the utmost point takes out, and being dissolved in volume ratio is completely in the phenol of 1:1 and the mixed solvent of glacial acetic acid, filters with deionized water and washs, vacuum drying 2 ~ 4h;

(2) preparation of the copper base composite powder that CNTs disperse distributes: the CNT that screening is obtained increases and mixes on planetary ball mill with copper alloy powder respectively in gradient by mass percentage, then carry out chemical nickel plating processing, the copper base composite powder that be prepared into good fluidity, be applicable to automatic powder feeding, CNTs disperse distributes;

(3) CNTs of gradient content strengthens the preparation of Cu-base composites: the copper base composite powder that the CNTs disperse of preparation is distributed adopts the method for multiple tracks multilayer laser-inductive composite meltization deposition, the CNTs disperse of preparation gradient content strengthens Cu-base composites, and the laser instrument of use is crossing current CO ₂laser instrument, the induction heater using is integration module type high frequency induction heater, and concrete technology parameter is: laser power 1 ~ 10kW, laser scanning speed 1 ~ 8m/min, spot diameter 0.5 ~ 5mm, induction heating power 10 ~ 150kW, powder feeding rate 30 ~ 300g/min, 45 ~ 53 ° of jet angles, overlapping rate 40 ~ 60%.

2. the CNTs of laser-inductive composite melt sedimentation gradient content according to claim 1 strengthens the method for Cu-base composites, it is characterized in that CNTs is 0.05 ~ 20wt% gradient along thickness direction and distributes, and the content of outermost layer CNTs is 20wt%.

3. the CNTs of laser-inductive composite melt sedimentation gradient content according to claim 1 strengthens the method for Cu-base composites, while it is characterized in that carrying out described step (1), rotation electrophoretic apparatus is installed in surface modification groove, the upper and lower electrode of rotation electrophoretic apparatus is that diameter is the circle of 100 ~ 500mm, and bottom electrode is positioned at the bottom of surface modification groove.

4. the CNTs of laser-inductive composite melt sedimentation gradient content according to claim 1 strengthens the method for Cu-base composites, while it is characterized in that carrying out described step (2), the chemical composition of copper alloy powder is: Zr 0.1 ~ 0.35wt%, Al 0.8 ~ 5wt%, Ni 0.1 ~ 0.25wt%, Y 0.01 ~ 0.025wt%, Hf 0.01 ~ 0.035wt%, surplus are Cu.

5. the CNTs of laser-inductive composite melt sedimentation gradient content according to claim 1 strengthens the method for Cu-base composites, while it is characterized in that carrying out described step (3), the complete one deck of every deposition, by laser-inductive composite melt processing head along the Z axis distance equating with CAD two-dimensional slice thickness that rises, in automatic powder feeding device, rejoin the copper base composite powder that CNTs disperse distributes simultaneously, wherein CNTs increases by 0.05 ~ 5wt% at the content in composite powder compared with deposition is when last layer, then carry out laser-inductive composite meltization deposition according to the track while scan of lower one deck, after all two-dimensional slice have all been scanned, the CNTs that forms three-dimensional content distribution gradient strengthens Cu-base composites.