Preparation method of reinforced copper-silver-based electrical contact composite material based on carbon nanotubes

Abstract

The invention relates to a method for preparing a carbon nanotube reinforced copper-silver-based electrical contact composite material based on a liquid phase atomization method, and belongs to the technical field of electrical contact preparation. The preparation method comprises the following steps: carrying out hot pressed sintering on mixed powder of reinforcement powder, copper powder and silver powder, solidifying the powder to form an Ag-coated CNTs / Cu-Ag composite material block, and then preparing the Ag-coated CNTs reinforced Cu-Ag-based electrical contact composite material through a process route of solid solution, extrusion and aging. The preparation method disclosed by the invention is simple to operate and stable in preparation process, and the mechanical and electrical properties of the prepared composite material can respectively reach 157HV and 103% IACS (International Annealed Copper Standard) and above; according to the method, ablation and damage of the surface of the electrical contact in the working process are relieved, the viscosity of a molten pool is increased, the contact resistance in the electrical contact process can be reduced, the current concentration phenomenon and the temperature rise effect at a contact point can be relieved, the mass loss of an electrical contact material is reduced, the maintenance cost is reduced, and the method has good application prospects in the field of electrical contact materials.

Description

Background Art

[0001] Electrical contact materials are used in switches, relays, electrical connections, and electrical connectors. Due to their crucial role in electrical components, they are known as the "heart of electrical appliances." In switchgear, they primarily serve the functions of disconnecting and connecting circuits, controlling the flow of current through contact or separation. During electrical connections, they also carry the current, directly impacting the equipment's switching capabilities, electrical lifespan, and reliability. They also serve as core components of low-voltage electrical appliances, high-voltage circuit breakers, switchgear, and other equipment, directly determining their operating efficiency and service life. Therefore, research and preparation of new electrical contact materials with high electrical and thermal conductivity, excellent friction resistance, and arc erosion resistance has become a key technology to break through existing material bottlenecks and extend the service life of electrical appliances.

[0002] At present, the mainstream electrical contact materials are mainly silver-based alloys, copper-based alloys and new nanomaterials, and their application scope covers high, medium and low voltage electrical contact application scenarios. Among them, traditional silver-based electrical contacts are prone to arc erosion in high voltage and high current environments, which shortens the contact life. At the same time, they also face problems such as high manufacturing costs and difficulty in production, making it difficult to achieve large-scale batch production and application. Traditional copper-based electrical contacts such as copper tungsten (CuW) and copper chromium (CuCr) have high tungsten and chromium content. Although this improves strength and reduces production costs, it seriously affects the electrical conductivity of the electrical contacts, resulting in a significant decline in electrical performance. At the same time, the low intrinsic thermal conductivity of added elements such as tungsten and chromium further leads to arc aggregation, resulting in a reduction in the arc erosion area on the surface of the electrical contact, affecting the arc erosion resistance of the electrical contact and accelerating the failure behavior of the electrical contact. Therefore, the development of copper materials with high strength, high conductivity, good thermal conductivity and wear resistance is an effective strategy to solve the application defects of electrical contact materials. Carbon nanotubes (CNTs), a typical one-dimensional carbon nanomaterial, have a low work function and excellent electrical properties. They can disperse the arc during arc erosion during electrical contact testing, dissipating arc energy and protecting the copper substrate. They can also increase the viscosity of the copper liquid under arcing, reduce copper splashing, improve arc stability, and extend the life of the electrical contact material. Therefore, the addition of CNTs can achieve a synergistic improvement in the overall performance of copper-based contact materials, making up for the limited application of traditional copper-based electrical contact materials. Summary of the Invention

[0003] In view of this, the present invention provides a method for preparing silver-loaded carbon nanotubes (Ag@CNTs)-reinforced Cu-Ag-based electrical contact materials using a liquid-phase atomization method. On the one hand, the Ag@CNTs prepared by the liquid-phase atomization method improve the intrinsic dispersibility of the CNTs and enhance the interfacial bonding strength between the CNTs and the copper-silver matrix, thereby achieving excellent electrical and thermal conductivity, reducing the contact resistance of the contact material, alleviating the temperature rise effect, and improving the service life of the electrical contacts. On the other hand, the Cu-Ag-based composite material prepared by the hot extrusion process fully utilizes the excellent electron transport capability of the CNTs along the axial direction, achieving both excellent electrical properties and good mechanical properties, and possessing outstanding resistance to arc erosion, meeting the requirements for the use of current new medium- and low-voltage electrical contact materials.

[0004] The objectives of the present invention are achieved through the following technical solutions.

[0005] A method for preparing a carbon nanotube-reinforced copper-based electrical contact composite material comprises the following steps: (1) Ag@CNTs reinforcement was prepared by liquid phase atomization of Ag-containing metal salt solution and carbon nanotubes (CNTs); (2) The precursor powder (Ag@CNTs) and copper powder (Cu) are mixed evenly to obtain Ag@CNTs / Cu composite powder; (3) The composite powder was placed in a mold with a diameter of 30 mm and sintered into a composite material block by rapid hot pressing, referred to as Ag@CNTs / Cu; (4) The Ag@CNTs / Cu bulk composite material was subjected to hot extrusion deformation treatment at 800~900℃ to obtain an Ag@CNTs reinforced copper-silver based electrical contact composite material; (5) During the deformation process, Ag was dissolved due to the high temperature. After hot extrusion, the rod was aged at a temperature of 350-450 °C and an aging time of 1-10 hours. Finally, a modified carbon nanotube reinforced copper-silver based electrical contact composite material was obtained.

[0006] Preferably, step (1) of preparing Ag@CNTs precursor powder comprises dispersing silver nitrate and carbon nanotube powder in pure water respectively, and then mixing to form a uniform mixed solution; the mixed solution is atomized into Ag@CNTs composite powder by liquid phase. The specific operation is as follows: first, 0.05-0.2g of CNTs carbon nanotube powder is placed in a beaker filled with pure water for ultrasonic dispersion, then 1.8-3g of silver nitrate is placed in 2000ml of pure water and stirred, and the dispersed CNTs dispersion is poured into the mixture and stirred for 30-60min. After stirring, the mixed solution is poured into an ultrasonic atomizer, the liquid is atomized and placed in a tube furnace at a temperature of 650-750°C for heat treatment, and the precursor powder is collected by electrostatic adsorption, referred to as Ag@CNTs.

[0007] Preferably, in the mixed solution, the concentration of silver nitrate is 0.6-1 g / L, and the concentration of carbon nanotubes is 0.017-0.07 g / L.

[0008] Preferably, the mixed powder described in step (2) is obtained by ball milling, which specifically includes the following steps: adding the precursor powder Ag@CNTs and copper powder into a ball mill, adding an organic solvent as a ball milling medium, setting the ball-to-material ratio to 10:1, the ball milling speed to 300~400 r / min, ball milling for 6~8h in the atmosphere, and vacuum drying after the ball milling to remove the organic solvent to obtain a uniformly mixed mixed powder, referred to as Ag@CNTs / Cu composite powder.

[0009] Preferably, the specific operation of step (3) is: loading the obtained composite powder into a mold with a diameter of 30 mm, and performing rapid hot pressing sintering, the sintering temperature is 750~850℃, the heating rate is 50~150℃ / min, the holding time is 15~25min, and the pressure is 50~120MPa.

[0010] Preferably, in step (4), the hot extrusion process has an extrusion ratio of 15:1 to 25:1 and an extrusion speed of 4 to 10 mm / s.

[0011] Preferably, in step (5), the aging treatment temperature is 350-450° C., and the aging treatment time is 1-10 hours.

[0012] Preferably, the carbon nanotubes in step (1) are single-walled, double-walled or multi-walled carbon nanotubes with an outer diameter of 50-100 nm and a length of 10-30 μm; the particle size of the copper powder is 20-50 μm.

[0013] Preferably, the mass ratio of the Ag@CNTs to the copper powder is 1:100 to 36:100; the mass fraction of Ag in the Ag@CNTs is 60 to 90%, and the mass fraction of Ag in the Ag@CNTs / Cu is 2 to 10%.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) The method of the present invention introduces CNTs into the traditional Cu-Ag based electrical contact material and uses Ag nanoparticles to modify the surface of CNTs using the liquid phase atomization method, which effectively improves the density difference between CNTs and the Cu-Ag matrix, alleviates the problem of CNTs agglomeration, and achieves uniform dispersion of CNTs; (2) The method of the present invention enhances the interface bonding between CNTs and the Cu-Ag matrix by adding Ag nanoparticles, fully exerts the arc dispersion effect of CNTs, alleviates the ablation and damage of the electric contact surface during operation, increases the viscosity of the molten pool, reduces the quality loss of the electric contact material, and reduces maintenance costs; (3) The present invention adopts a hot extrusion technology route to prepare CNTs reinforced Cu-Ag based electrical contact composite materials, which can achieve directional arrangement of CNTs, reduce contact resistance during electrical contact, alleviate current concentration and temperature rise effect at the contact point, reduce the mass loss of electrical contacts, delay the welding phenomenon between contacts, and improve the service life of electrical contacts; (4) The preparation route described in the present invention has stable process effects, short preparation cycle, reasonable cost control, strong practicality, and has considerable application prospects in the field of electrical contact. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Transmission electron microscopy (TEM) images of the Ag@CNTs composite powder in step (1) of Example 1 at different magnifications and energy dispersive spectroscopy (EDS) analysis; Figure 2 TEM image of step (5) in the implementation case, and energy spectrum analysis of Ag and CNTs; Figure 3 Comparison of the conductivity and hardness bar graphs of the Ag@CNTs / Cu composite material prepared in Example 1 and the CNTs / Cu prepared in Comparative Example 1; Figure 4 Comparison of arc energy and welding force between the Ag@CNTs / Cu composite material prepared in Example 1 and the CNTs / Cu prepared in Comparative Example 1; Figure 5 Comparison of the conductivity and hardness bar graphs of the Ag@CNTs / Cu composite material prepared in Example 2 and the CNTs / Cu prepared in Comparative Example 2; Figure 6Comparison of arc energy and welding force between the Ag@CNTs / Cu composite material prepared in Example 2 and the CNTs / Cu prepared in Comparative Example 2; Figure 7 Comparison of the conductivity and hardness bar graphs of the Ag@CNTs / Cu composite material prepared in Example 3 and the CNTs / Cu prepared in Comparative Example 3; Figure 8 Comparison of arc energy and welding force of Ag@CNTs / Cu composite material prepared in Example 3 and CNTs / Cu prepared in Comparative Example 3; DETAILED DESCRIPTION

[0016] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, wherein the methods are conventional methods unless otherwise specified, and the raw materials can be obtained from public commercial channels unless otherwise specified.

[0017] In the following embodiments: The purity of CNTs powder is 99 wt.%, the outer diameter is 50-100 nm, and the length is 10-30 μm. It is produced by Zhongke Times Nanotechnology Co., Ltd. AgNO3 is colorless or white crystals with a purity of ≥99.8wt.%, Sinopharm Chemical Reagent Co., Ltd. The Cu powder has a purity of 99.9%, a particle size of 20-50 μm, and a dendritic morphology. It is manufactured by Shanghai Naio Nanotechnology Co., Ltd. Ag powder with a purity of 99% and a particle size of 300 nm was purchased from MacLean Chemical Reagent Co., Ltd. Scanning electron microscope: Nova Nano-450, FEI, USA; Mechanical Properties: Tensile tests were conducted at room temperature using a universal tensile testing machine (AUTOGRAPH AG-I, Shimadzu Corporation, Japan). The specimen dimensions (dogbone type) were 16 mm × 2 mm × 1.5 mm (length × width × thickness), and the tensile rate was 0.2 mm / min.

[0018] Electrical contact performance characterization: Electrical contact tests were conducted at room temperature using an electrical contact material tester (JF04C, Kunming, China). The test voltage was 24 V, the current was 10 A, the number of interruptions was 5000, the opening distance was 1 mm, and the breaking time was 1 s.

[0019] Example 1 A method for preparing an Ag@CNTs-reinforced Cu-Ag-based electrical contact material is as follows: (1) Place 0.05 g of carbon nanotubes in a beaker filled with pure water, ultrasonicate for 30 min, stir for 10 min every 10 min, and then place 1.8 g of silver nitrate in 2000 ml of pure water and stir. Pour the dispersed CNTs solution into the beaker and continue stirring. Then, keep the mixed solution in a stirring state and place it in an ultrasonic atomizer. Atomize the liquid into a 650 °C tube furnace and collect the Ag@CNTs powder by electrostatic adsorption. (2) 1.4 g of the collected Ag@CNTs was mixed with 30 g of pure Cu powder at a ball-to-material ratio of 10:1, 50 ml of organic solvent was added, the ball milling speed was 300 r / min, 6 h, and vacuum dried to obtain composite powder Ag@CNTs; (3) 50 g of Ag@CNTs composite powder was placed in a mold with a diameter of 30 mm, the pressure was 50 MPa, and the temperature was kept at 750 °C for 25 min at a heating rate of 50 °C / min. After sintering, the composite material block was obtained by cooling in the furnace. (4) The Ag@CNTs / Cu composite block was extruded and deformed by hot extrusion, wherein the extrusion temperature was 800°C, the extrusion ratio was 15:1, and the extrusion speed was 4 mm / s. After extrusion, an Ag@CNTs / Cu electrical contact material with a diameter of 8 mm was obtained; (5) During the deformation process, Ag was dissolved due to the high temperature. After hot extrusion, the bar was aged at 350 °C for 1 hour.

[0020] In order to verify the dispersion effect of liquid phase atomization on CNTs, the morphology and energy spectrum of Ag@CNTs after liquid phase atomization were characterized by TEM. Figure 1 (a) and Figure 1 (b) is the TEM image of Ag@CNTs precursor at different magnifications. Figure 1 (b) The element distribution surface was scanned under a transmission electron microscope. The element distribution is shown in Figure 1 (c) and Figure 1 As shown in (d), it can be observed that the Ag particles are uniformly dispersed on the CNTs, and some of the Ag forms a strip structure after hot extrusion. Figure 2 (c) and Figure 2 As shown in (d), after hot extrusion, CNTs and Ag composite powders are evenly dispersed, which helps to reduce the contact resistance of Ag in electrical contact work. CNTs play a role in dispersing arcs, consuming arc energy, and protecting the copper matrix during arc erosion. At the same time, they can also improve the viscosity of copper liquid under arc action, avoid arc concentration caused by Ag phase agglomeration, and effectively improve the arc erosion resistance of the contact and the service life of the electrical contact.

[0021] Comparative Example 1 (1) Weigh 1.2 g of Ag powder and 30 g of pure Cu powder, place them in a beaker filled with 50 ml of organic solvent, stir for 30 min, pour them into a ball mill with a ball-to-material ratio of 10:1, and ball mill at a speed of 300 r / min for 6 h. After ball milling, dry them under vacuum to remove alcohol to obtain Cu-Ag composite powder; (2) 50 g of Cu-Ag composite powder was placed in a graphite sintering mold with an inner diameter of 30 mm, and the mold was placed in a rapid hot pressing sintering furnace. The furnace was evacuated to vacuum, the sintering pressure was 50 MPa, and the temperature was kept at 750 °C for 25 min at a heating rate of 50 °C / min. After sintering, the composite material block was obtained by cooling in the furnace. (3) The Cu-Ag composite block was extruded and deformed by hot extrusion, wherein the extrusion temperature was 800°C, the extrusion ratio was 15:1, and the extrusion speed was 4 mm / s, and a Cu-Ag electrical contact material with a diameter of 8 mm was obtained after extrusion; (4) During the deformation process, Ag was dissolved due to the high temperature. After hot extrusion, the bar was aged at 350 °C for 1 hour.

[0022] If Cu and Ag powders are directly dispersed and mixed by ball milling, Ag's low melting point (964°C) and poor hardness will result in poor resistance to welding and wear during the disconnection process of electrical contact testing, limiting its further application. Therefore, the surface of carbon nanotubes is modified by liquid phase atomization, and Ag is loaded on CNTs. This eliminates the density difference between CNTs and Cu and changes the interface between Cu and CNTs. This not only helps disperse CNTs in Cu, but also utilizes the conductivity of Ag to ensure that the conductivity of the composite material is not reduced, improving the arc erosion resistance of the Cu-Ag contact and extending its service life.

[0023] The mechanical properties of the composite materials prepared in Example 1 and Comparative Example 1 were characterized respectively. The test results are as follows: Figure 3 As shown, the microhardness of the composite material of Example 1 (about 98 HV) is improved compared with the microhardness of the composite material of Comparative Example 1 (about 80 HV). International standard annealed copper is used for electrical conduction, and the electrical conductivity of Example 1 (92% IACS) is improved compared with the electrical conductivity of the composite material of Comparative Example 1 (about 80% IACS). This is because the effective dispersion of CNTs improves the interface bonding between Cu and CNTs, and the grains are refined during the hot extrusion process. During aging precipitation, Ag, as a precipitated phase, hinders dislocation movement, thereby improving the strength of the composite material. In addition, Ag, as the metal with the best conductivity, also plays a role in low resistance in the composite material, ensuring the conductivity of the composite material.

[0024] The electrical contact performance test (24 V, 10 A, 5000 times) was carried out on the composite materials prepared in Example 1 and Comparative Example 1. The results are as follows: Figure 4 As shown, the arc energy and arc burning time of the composite material of Example 1 are significantly lower than the arc energy and welding force of the composite material of Comparative Example 1. On the one hand, the preparation of Ag@CNTs by liquid phase atomization improves the intrinsic dispersibility of CNTs and enhances the interfacial bonding strength between CNTs and the copper-silver matrix, which is conducive to achieving excellent electrical and thermal conductivity, reducing the contact resistance of the contact material, alleviating the temperature rise effect, and improving the service life of the electrical contact; on the other hand, the Cu-Ag-based composite material prepared by hot extrusion fully utilizes the excellent electron transmission ability of CNTs along the axial direction, taking into account excellent electrical properties while ensuring good mechanical properties, and has outstanding resistance to arc erosion, meeting the current requirements for the use of new medium and low voltage electrical contact materials.

[0025] Example 2 A method for preparing an Ag@CNTs-reinforced Cu-Ag-based electrical contact material is as follows: (1) Place 0.1 g of carbon nanotubes in a beaker filled with pure water, ultrasonicate for 30 min, stir for 10 min every 10 min, and then place 2.5 g of silver nitrate in 2000 ml of pure water and stir. Pour the dispersed CNTs solution into the beaker and continue stirring. Then, keep the mixed solution in a stirring state and place it in an ultrasonic atomizer. Atomize the liquid into a 700 °C tube furnace and collect Ag@CNTs by electrostatic adsorption. (2) 1.8 g of the collected Ag@CNTs was mixed with 30 g of pure Cu powder at a ball-to-material ratio of 10:1, 50 ml of organic solvent was added, and the ball milling speed was 350 r / min for 7 h. The composite powder Ag@CNTs was obtained by vacuum drying. (3) 50 g of Ag@CNTs composite powder was placed in a mold with a diameter of 30 mm, the pressure was 100 MPa, and the temperature was kept at 800 °C for 20 min at a heating rate of 100 °C / min. After sintering, the composite material block was obtained by cooling in the furnace. (4) The Ag@CNTs / Cu composite block was extruded and deformed by hot extrusion, wherein the extrusion temperature was 850°C, the extrusion ratio was 20:1, and the extrusion speed was 8 mm / s. After extrusion, an Ag@CNTs / Cu electrical contact material with a diameter of 8 mm was obtained; (5) During the deformation process, Ag was dissolved due to the high temperature. After hot extrusion, the bar was aged at 400 °C for 5 hours.

[0026] Comparative Example 2 (1) Weigh 1.5 g of Ag powder, put it into the 50 ml organic solvent beaker and stir 30 ml, and pour it into a ball mill with a ball-to-material ratio of 10:1. Ball milling is carried out at a speed of 350 r / min for 7 h. After ball milling, it is dried under vacuum conditions to remove alcohol to obtain Cu-Ag composite powder; (2) 50 g of Cu-Ag composite powder was placed in a graphite sintering mold with an inner diameter of 30 mm, and the mold was placed in a rapid hot pressing sintering furnace. The furnace was evacuated to a vacuum with a pressure of 100 MPa and kept at 800 °C for 20 min at a heating rate of 100 °C / min. After sintering, the composite material block was obtained by cooling in the furnace. (3) The Cu-Ag composite block was extruded and deformed by hot extrusion, wherein the extrusion temperature was 850°C, the extrusion ratio was 20:1, and the extrusion speed was 8 mm / s, and a Cu-Ag electrical contact material with a diameter of 8 mm was obtained after extrusion; (4) During the deformation process, Ag was dissolved due to the high temperature. After hot extrusion, the bar was aged at 400 °C for 5 hours.

[0027] The conductivity and hardness of the composite materials prepared in Example 2 and Comparative Example 2 were tested respectively. The results are as follows: Figure 5 As shown in Figure 3, the composite material with the addition of Ag@CNTs has higher conductivity (about 103% IACS) and higher hardness (increased to about 157 HV).

[0028] The electrical contact performance test (24 V, 10 A, 5000 times) was carried out on the composite materials prepared in Example 2 and Comparative Example 2. The results are as follows: Figure 6 As shown, the arc energy and arc burning time of the composite material of Example 2 are significantly reduced compared with the arc energy and arc burning time of the composite material of Comparative Example 2, and the arc energy and welding force of the composite material of Example 2 are more stable during the breaking process.

[0029] Example 3 A method for preparing an Ag@CNTs-reinforced Cu-Ag-based electrical contact material is as follows: (1) Place 0.2 g of carbon nanotubes in a beaker filled with pure water, ultrasonicate for 30 min, stir for 10 min every 10 min, and then place 3 g of silver nitrate in 2000 ml of pure water and stir. Pour the dispersed CNTs solution into the beaker and continue stirring. Then, keep the mixed solution in a stirring state and place it in an ultrasonic atomizer. Atomize the liquid into a 750 °C tube furnace and collect Ag@CNTs by electrostatic adsorption. (2) 2 g of the collected Ag@CNTs were mixed with 30 g of pure Cu powder at a ball-to-material ratio of 10:1, 50 ml of organic solvent was added, the ball milling speed was 400 r / min, 8 h, and vacuum dried to obtain composite powder Ag@CNTs; (3) 50 g of Ag@CNTs composite powder was placed in a mold with a diameter of 30 mm, the pressure was 120 MPa, and the temperature was kept at 850 °C for 15 min at a heating rate of 150 °C / min. After sintering, the composite material block was obtained by cooling in the furnace. (4) The Ag@CNTs / Cu composite block was extruded and deformed by hot extrusion, wherein the extrusion temperature was 900°C, the extrusion ratio was 25:1, and the extrusion speed was 10 mm / s. After extrusion, an Ag@CNTs / Cu electrical contact material with a diameter of 8 mm was obtained; (5) During the deformation process, Ag was dissolved due to the high temperature. After hot extrusion, the bar was aged at 450 °C for 10 hours.

[0030] Comparative Example 3 (1) Weigh 2 g of Ag powder, put it into the 50 ml organic solvent beaker and stir 30 ml, and pour it into a ball mill with a ball-to-material ratio of 10:1. Ball milling is carried out at a speed of 400 r / min for 8 h. After ball milling, it is dried under vacuum to remove alcohol to obtain Cu-Ag composite powder; (2) 50 g of Cu-Ag composite powder was placed in a graphite sintering mold with an inner diameter of 30 mm, and the mold was placed in a rapid hot pressing sintering furnace. The furnace was evacuated to a vacuum with a pressure of 120 MPa, and the temperature was kept at 850 °C for 15 min at a heating rate of 150 °C / min. After sintering, the composite material block was obtained by cooling in the furnace. (3) The Cu-Ag composite block was extruded and deformed by hot extrusion, wherein the extrusion temperature was 900°C, the extrusion ratio was 25:1, and the extrusion speed was 10 mm / s, and a Cu-Ag electrical contact material with a diameter of 8 mm was obtained after extrusion; (4) During the deformation process, Ag was dissolved due to the high temperature. After hot extrusion, the bar was aged at 450 °C for 10 hours. The conductivity and hardness of the composite materials prepared in Example 3 and Comparative Example 3 were tested respectively. The results are as follows: Figure 7 As shown in Figure 3, the composite material with the addition of Ag@CNTs has higher conductivity (about 100% IACS) and higher hardness (increased to about 110HV).

[0031] The electrical contact performance test (24 V, 10 A, 5000 times) was carried out on the composite materials prepared in Example 3 and Comparative Example 3. The results are as follows: Figure 8As shown, the arc energy and welding force of the composite material of Example 3 are significantly reduced compared with the arc energy and arc burning time of the composite material of Example 3, and the arc energy and arc burning time of the composite material of Example 3 are more stable during the breaking process.

[0032] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a carbon nanotube-reinforced copper-silver-based electrical contact composite material, characterized in that: The following steps are involved: (1) Ag-containing compounds and carbon nanotubes (CNTs) are prepared by liquid phase atomization to obtain Ag@CNTs precursor powder; (2) Mixing Ag@CNTs precursor powder and copper powder evenly to obtain mixed powder; (3) The mixed powder is placed in a mold and sintered into a composite material block by rapid hot pressing, referred to as Ag@CNTs / Cu; (4) The Ag@CNTs / Cu bulk composite material was subjected to hot extrusion deformation treatment at 800~900℃; (5) The material obtained by hot extrusion is subjected to aging treatment to obtain a modified carbon nanotube reinforced copper-silver based electrical contact composite material.

2. The method for preparing the carbon nanotube-reinforced copper-silver based electrical contact composite material according to claim 1, characterized in that: The mixed powder in step (2) is obtained by ball milling, which specifically includes the following steps: The precursor powders Ag@CNTs and copper powder were added to a ball mill, and an organic solvent was added as the ball milling medium. The ball-to-material ratio was set to 10:1, the ball milling speed was 300-400 r / min, and the ball milling was carried out under atmospheric pressure for 6-8 hours. After ball milling, the composite powder, namely Ag@CNTs / Cu composite powder, was obtained by vacuum drying.

3. The method for preparing the carbon nanotube-reinforced copper-silver based electrical contact composite material according to claim 1 or 2, characterized in that: Step (1) Preparation of Ag@CNTs precursor powder: Silver nitrate and carbon nanotube powder are dispersed in pure water respectively, and then stirred and mixed to form a uniform mixed solution; the mixed solution is formed into Ag@CNTs composite powder through liquid phase atomization.

4. The method for preparing the carbon nanotube-reinforced copper-silver based electrical contact composite material according to claim 3, characterized in that: In the mixed solution, the concentration of silver nitrate is 0.6~1 g / L, and the concentration of carbon nanotubes is 0.017~0.07g / L.

5. The method for preparing the carbon nanotube-reinforced copper-silver based electrical contact composite material according to claim 3, wherein: The liquid phase atomization method is to pour the mixed solution into an ultrasonic atomizer, atomize the liquid into a tube furnace with a temperature of 650~750℃, and collect the precursor powder by electrostatic adsorption, referred to as Ag@CNTs.

6. The method for preparing the carbon nanotube-reinforced copper-silver based electrical contact composite material according to claim 1, characterized in that: The carbon nanotubes in step (1) are single-walled, double-walled or multi-walled carbon nanotubes with an outer diameter of 50-100 nm and a length of 10-30 μm; the particle size of the copper powder in step (2) is 20-50 μm.

7. The method for preparing the carbon nanotube-reinforced copper-silver based electrical contact composite material according to claim 1 or 2, characterized in that: In step (3), the sintering temperature is 750-850°C, the heating rate is 50-150°C / min, the sintering pressure is 50-120 MPa, and the sintering time is 15-25 min.

8. The method for preparing the carbon nanotube-reinforced copper-silver based electrical contact composite material according to claim 1 or 2, characterized in that: In step (4), the hot extrusion process has an extrusion ratio of 15:1 to 25:1 and an extrusion speed of 4 to 10 mm / s.

9. The method for preparing the carbon nanotube-reinforced copper-silver based electrical contact composite material according to claim 1 or 2, characterized in that: In step (5), the aging treatment temperature is 350-450°C, and the aging time is 1-10 hours.

10. The method for preparing the carbon nanotube-reinforced copper-silver based electrical contact composite material according to claim 1, characterized in that: The mass ratio of the Ag@CNTs to the copper powder is 1:100-36:100; the mass fraction of Ag in the Ag@CNTs is 60-90%, and the mass fraction of Ag in the Ag@CNTs / Cu is 2-10%.

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