A three-dimensional network carbon phase reinforced copper-based composite material and preparation method thereof

Abstract

The present invention relates to a three-dimensional network carbon phase reinforced copper-based composite material and a preparation method thereof; it belongs to the technical field of carbon / copper composite material design and preparation. The composite material comprises short carbon fibers, carbon nanotubes, and a matrix, wherein the matrix is ​​copper or a copper alloy; wherein the short carbon fibers and carbon nanotubes are distributed in a copper and / or copper alloy matrix, wherein the short carbon fibers serve as a primary reinforcement, and the carbon nanotubes serve as a secondary reinforcement, and all or part of the carbon nanotubes are fixed on the short carbon fibers by in-situ growth. The preparation method comprises: taking short carbon fibers of different lengths according to the components involved; then depositing and generating carbon nanotubes on the short carbon fibers; obtaining CNT‑Cf; and then obtaining the composite material by a melt infiltration process. The composite material of the present invention has a reasonable structural design, a simple and controllable preparation process, and excellent performance of the obtained product, which is convenient for large-scale industrial application.

Description

Technical Field

[0001] The invention relates to a three-dimensional network carbon phase reinforced copper-based composite material and a preparation method thereof, and belongs to the technical field of design and preparation of carbon / copper composite materials. Background Art

[0002] In the fields of railways, light rails, subways, and motors, sliding collector materials (pantograph slides, collector shoes, or sliders) are required to obtain current from copper wires or conductive rails during operation. The matching performance of sliding collector materials / conductive meshes is crucial to the safe operation of high-speed trains and motors, which requires sliding collector materials to have high mechanical properties, low resistance, excellent wear resistance, and lubricity.

[0003] Carbon-based composite materials (copper-impregnated carbon slides and pure carbon slides) are widely used as sliding collector materials due to their good self-lubricating properties, but their toughness and strength are poor, and the worn surface is prone to rupture and collapse, resulting in abnormal wear. Graphite / copper-based composite materials have high strength, low resistance, excellent thermal and electrical conductivity, and good wear resistance, and are widely used in pantograph slides and motor brushes, but the lubrication and friction properties of graphite / copper-based slide materials are insufficient, and they are prone to cause large wear on copper meshes. This is because there is a large difference in density between graphite and copper powder. During the powder metallurgy ball milling preparation process of graphite / copper-based composite materials, graphite and copper powder are prone to stratification, causing graphite powder agglomeration, and the lubricity of graphite / copper-based composite materials is difficult to fully exert.

[0004] Carbon fiber reinforced copper / carbon composites have attracted the attention of researchers and have shown excellent mechanical properties, electrical conductivity, and friction and wear properties. However, there has been no breakthrough in industrialization. The main reasons are the complex preparation process of this type of composite material and the high cost of long carbon fibers. Short carbon fiber reinforced carbon-based skateboards have the problem of difficulty in uniformly dispersing carbon fibers and insufficient carbon fiber reinforcement effect. In the Northwestern Polytechnical University patent [CN101525730A] - low-pressure assisted melt infiltration preparation method for high volume fraction C / Cu composite materials, the inventor prepares a preform by mixed carbonization of short carbon fibers and phenolic resin, and prepares a short carbon fiber reinforced C / Cu-based composite material by low-pressure assisted melt infiltration. The composite material has a high volume carbon content; however, the thermal matching and shrinkage of the short carbon fibers and the resin during the carbonization process are quite different. After carbonization, the interface bonding strength between the carbon fibers and the resin carbon matrix is ​​poor, and the carbon fibers are easy to pull out, making it difficult to give full play to the reinforcement effect of the short carbon fibers. Summary of the invention

[0005] In response to the above-mentioned problem of sliding collector materials, this patent proposes for the first time to use low-cost short carbon fibers instead of long carbon fibers or graphite as lubricating components, combined with carbon nanotubes (CNTs) to form a three-dimensional network structure reinforced copper-based composite material, namely, in-situ CNT-modified carbon fiber / copper-based composite material (CNT-Cf / copper-based composite material).

[0006] In view of the complex weaving process of long carbon fiber and the difficulty of dispersing graphite powder by ball milling, this patented material uses short carbon fiber stacking + CVD deposition pyrolytic carbon shaping preform to make the short carbon fiber evenly dispersed in the CNT-Cf / copper-based composite material; based on the multi-level reinforcement theory of tree root system, short carbon fiber is the first-level reinforcement (root trunk), CNT is the second-level reinforcement (root whisker), and short carbon fiber and CNT form a three-dimensional network structure to improve the comprehensive performance of the copper matrix (mechanical properties, electrical and thermal conductivity, and friction and wear properties). CNT-Cf / copper-based composite materials have good interface bonding and high density. This type of composite material has high electrical and thermal conductivity, high mechanical properties, excellent wear resistance and self-lubricating properties. At the same time, its preparation process is simple and easy to control. It is a new type of sliding collector material with good market prospects.

[0007] The present invention discloses a three-dimensional network carbon phase reinforced copper-based composite material, which comprises short carbon fibers, carbon nanotubes and a matrix, wherein the matrix is ​​copper or a copper alloy; wherein the short carbon fibers and the carbon nanotubes are distributed in the copper and / or copper alloy matrix, the short carbon fibers serve as a primary reinforcement, the carbon nanotubes serve as a secondary reinforcement, and all or part of the carbon nanotubes are fixed on the short carbon fibers by in-situ growth.

[0008] The present invention discloses a three-dimensional network carbon phase reinforced copper-based composite material, wherein the short carbon fibers are composed of short chopped carbon fibers of different lengths, and the length of the short carbon fibers is less than or equal to 100 mm, preferably less than or equal to 30 mm, and more preferably less than or equal to 20 mm.

[0009] As a further preference, the chopped carbon fibers of different lengths include carbon fibers with a length of 15 to 20 mm, carbon fibers with a length of 6.5 to 13.5 mm, and carbon fibers with a length of 4.5 to 5.5 mm.

[0010] As a further preference, carbon fibers with a length of 15 to 20 mm, carbon fibers with a length of 6.5 to 13.5 mm, and carbon fibers with a length of 4.5 to 5.5 mm are composed in a mass ratio of A:B:C, wherein A and C are smaller than B.

[0011] In a further preferred embodiment, A is equal to 0.4 to 0.6 times B, and C is equal to 0.4 to 0.6 times B.

[0012] The invention discloses a three-dimensional network carbon phase reinforced copper-based composite material, wherein the mass of the carbon nanotubes is 1-20% of the mass of the short carbon fibers, preferably 6.5-13.5%.

[0013] The present invention discloses a three-dimensional network carbon phase reinforced copper-based composite material, wherein the total volume of carbon nanotubes and short carbon fibers accounts for 5-40% of the volume of the three-dimensional network carbon phase reinforced copper-based composite material, preferably 23-28%. That is, in the present invention, the volume of the three-dimensional network carbon phase reinforced copper-based composite material is defined as V; the total volume of carbon nanotubes and short carbon fibers in the three-dimensional network carbon phase reinforced copper-based composite material with a volume of V is defined as V. 碳 , V 碳 / V*100%=5-40%, preferably 23-28%.

[0014] The invention is based on the multi-level reinforcement theory of tree root system, short carbon fiber is used as the primary reinforcement, CNT is used as the secondary reinforcement, carbon fiber and CNT form a three-dimensional network structure to strengthen copper-based composite material; short carbon fiber and CNT are used as reinforcement and lubrication components, and short fiber stacking, pyrolysis carbon layer deposition, CNT in-situ growth and embedding and impregnation of copper alloy are used to prepare CNT-Cf / copper-based composite material with excellent performance. The preparation process of the invention is simple, easy to control and low in cost.

[0015] The present invention provides a method for preparing a three-dimensional network carbon phase reinforced copper-based composite material, comprising the following steps:

[0016] Step A

[0017] According to the components involved, short carbon fibers of different lengths are selected; then carbon nanotubes are deposited on the short carbon fibers to obtain CNT-Cf;

[0018] Step B

[0019] The powder with the nominal composition of the copper matrix design component is covered on the CNT-Cf;

[0020] Or the CNT-Cf is embedded in a powder with a nominal composition of the copper matrix design component, and sintered to obtain a product; the sintering temperature is greater than or equal to the melting temperature of the powder.

[0021] Preferably, in step A, a short carbon fiber porous body is obtained by pressing; then pyrolytic carbon is deposited on the short carbon fiber porous body by a CVI process to obtain a short carbon fiber porous body with pyrolytic carbon, and then carbon nanotubes are in situ generated on the short carbon fiber porous body with pyrolytic carbon by a chemical vapor deposition process.

[0022] In specific industrial applications, short carbon fibers of different lengths are selected for proportioning (for example, the fiber size ratio is linearly distributed or normally distributed, or in accordance with other design requirements of the present invention), the pore connectivity of the later carbon fiber preform is controlled, and the density of the Cf / copper-based composite material is optimized; the short chopped carbon fibers are stacked in a graphite mold, and the gaps between the carbon fibers are adjusted by shaking, vibrating, and pressing to prepare a short carbon fiber porous body.

[0023] In specific industrial applications, CVI deposits a pyrolytic carbon layer to fix the short carbon fiber structure. That is, pyrolytic carbon is deposited on the short carbon fiber porous body through the CVI process to obtain a short carbon fiber porous body with pyrolytic carbon; the CVI process conditions used are: temperature of 850-1150℃, pressure of 800-1200Pa; carbon source C3H6 gas flow rate of 1-3L / min, dilution gas N2 flow rate of 2-6L / min; deposition time of 50-300h.

[0024] In specific industrial applications, when carbon nanotubes are in situ generated on a porous body of short carbon fibers with pyrolytic carbon by chemical vapor deposition, the following process is used:

[0025] First, the electroplated nickel layer provides a catalyst for CNT preparation. The electroplating current is 9-16A, the plating solution is 9-16wt% Ni4SO4, and the electroplating time is 4-7h. The nickel-plated sample is transferred to the deposition furnace, and then CVD grows CNT. The CVD process conditions are: temperature 700-1100℃, pressure 1-500Pa; carbon source C3H6 gas flow rate 50-110cm 3 / min, the dilution gas N2 flow rate is 150-450cm 3 / min, the reducing gas H2 flow rate is 150-250cm 3 / min; the morphology of CNT is regulated by controlling the gas flow rate, and the diameter and length of CNT are regulated by controlling the deposition temperature and time. Finally, graphitization treatment is performed. Carbon fibers include asphalt-based carbon fibers and polyacrylonitrile (PAN)-based carbon fibers, and the chopped carbon fibers have a size of 0.5mm-100mm; the temperature is raised to the required temperature (1600-2800℃) and kept warm for 30min-5h.

[0026] In the present invention, the copper content in the copper matrix is ​​greater than 95 wt %. As a further preferred embodiment, the copper matrix contains copper, nickel and chromium.

[0027] As a further preferred embodiment, the copper matrix contains copper, nickel, and chromium, and the ratio of copper: nickel: chromium = 100-102: 1.8-2.2: 0.8-1.2. Of course, the copper matrix may also contain other metal elements M, and the mass ratio of M to copper is copper: M = 100-102: 08-1.2; and M is selected from at least one of tin, zirconium, tungsten, titanium, silicon, lead, molybdenum, aluminum, and iron.

[0028] When applied in industry, in step B, the graphite mold containing the CNT-Cf preform and the copper alloy powder or copper powder is transferred into a sintering furnace, evacuated, heated until the copper alloy or copper is melted, and kept warm for a certain time; N2 or Ar or H2 is passed as protection, a certain pressure (0.5-100MPa) is added, and the heat and pressure are maintained for melt infiltration, and the CNT-Cf / copper-based composite material is obtained after cooling. The heating temperature is preferably 1100-1250°C, and the time is 5min-180min. When applied in industry, the pressure can be controlled at 0.5-6MPa, and more preferably 3-5MPa during melt infiltration.

[0029] The present invention controls the carbon fiber content and density of the CNT-Cf / copper-based composite material by adjusting the ratio of short-cut carbon fibers of different lengths, controls the CNT morphology and size by adjusting the CVD process, controls the interface wettability between the copper matrix and the carbon fibers by adjusting the copper alloy ratio, and improves the densification effect of the embedded and impregnated CNT-Cf / copper-based composite material.

[0030] The present invention adopts carbon fiber and CNT to form a three-dimensional network structure to strengthen the copper-based composite material. The CNT-modified carbon fiber / copper-based composite material is a new type of sliding current collector material with the advantages of high electrical conductivity, high thermal conductivity, self-lubrication, low cost and easy industrialization.

[0031] The present invention uses carbon fiber and CNT to form a three-dimensional network structure to strengthen the copper-based composite material. The impact strength of the obtained CNT-Cf / copper-based composite material is 4.3-5.2 kj / m 2 , hardness of 72-81 HRB, conductivity of 42.5-56% AICS. After optimization, the impact strength of the obtained CNT-Cf / copper matrix composite material is 4.6-5.2 kj / m 2 , hardness is 75~81HRB, and conductivity is 49~56%AICS.

[0032] The present invention uses carbon fiber and CNT to form a three-dimensional network structure to strengthen the copper-based composite material. The friction coefficient of the obtained CNT-Cf / copper-based composite material is 0.08-0.14 and the wear rate is 1.05-2.87mm / 10000km under the conditions of 50A, speed 100km / h and load 90N. After optimization, the friction coefficient of the obtained CNT-Cf / copper-based composite material is 0.08-0.11 and the wear rate is 1.05-1.25mm / 10000km under the conditions of 50A, speed 100km / h and load 90N.

[0033] Compared with the prior art (copper-based powder metallurgy skateboard and carbon-based skateboard), the advantages and positive effects of the present invention are as follows:

[0034] (1) Compared with the dispersion of short carbon fibers (graphite powder) in the powder metallurgy method and the melting and impregnation method, the preparation of CNT-Cf / copper-based composite materials using carbon fiber stacking-CVD fixed structure-embedding impregnation densification can make the short carbon fibers more evenly dispersed, and the preparation process is simple and easy to control and industrialize. CNT-Cf / copper-based composite materials have the advantages of high electrical conductivity, high thermal conductivity, self-lubrication, low cost and easy industrialization. They are a new type of sliding current collector material with good market prospects.

[0035] (2) Short carbon fibers are used instead of graphite powder as the lubricating phase to improve the lubrication performance of the composite material while increasing its strength and toughness; short carbon fibers are used instead of long carbon fibers to reduce costs.

[0036] Long CNTs are introduced and combined with short fibers to form a three-dimensional reinforcement structure, such as the reinforcement of soil by tree roots (e.g. Figure 2 ), short carbon fibers are primary reinforcement (root trunk), and long CNTs are secondary reinforcement (root whiskers), which improve the mechanical properties, thermoelectric properties, and friction and wear properties of the composite material as a whole. This is because: 1. CNTs improve the interface bonding between carbon fibers and copper matrix, and carbon fibers are not easy to be pulled out and fall off, thereby improving the reinforcement effect of carbon fibers; 2. CNTs combine with short carbon fibers to form a three-dimensional interconnected structure to improve thermal and electrical conductivity; 3. CNTs improve the wear resistance of the copper matrix in the low-density carbon fiber area, while improving the lubrication performance of this area. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The preparation flow chart of CNT-Cf / copper-based composite materials;

[0038] Figure 2 The diagrams are hierarchical reinforcement principle diagrams, where (a) is a schematic diagram of the root reinforcement principle of a tree, and (b) is a schematic diagram of the three-dimensional reinforcement principle of a CNT-Cf / copper-based composite material;

[0039] Figure 3 The microscopic morphology photograph of the CNT-Cf preform obtained in implementation 1;

[0040] Figure 4 The friction coefficient diagram of the copper-based composite material obtained in the embodiment and the comparative example;

[0041] Figure 5 The wear rates of the copper-based composite materials obtained in the examples and comparative examples are shown in FIG. DETAILED DESCRIPTION

[0042] Comparative Example 1

[0043] Transfer the asphalt-based carbon fiber with a length of 5 mm into the graphitization furnace, heat it to 2000℃, keep it warm for 1.5 hours, and carry out graphitization treatment. Mix copper powder: nickel powder: chromium powder at a ratio of 100:2:1, add asphalt-based carbon fiber balls with a length of 10 mm, ball mill (60-240min, speed 20-45n / min) and mix them evenly. Transfer the mixed powder into the mold for molding (300-500MPa) to prepare a cold billet. Put the cold billet into the sintering furnace, the sintering temperature is 850-950℃, keep it warm for 5-60min, and use hydrogen as the protective gas. After cooling, the Cf / copper-based composite material is obtained.

[0044] The carbon fiber density in the Cf / copper-based composite material is low and the aspect ratio is large. During the ball milling process, more carbon fibers float on the upper part of the composite material to form agglomerates. The carbon fiber content in the Cf / copper-based composite material is about 15 vol%, the degree of graphitization is 19.9%, and the porosity is 8.3%. The impact strength of the composite material is 1.6 kj / m 2 , hardness is 51HRB, conductivity is 20.3%AICS. Under the conditions of 50A, speed 100km / h, load 90N, the friction coefficient of the composite material is 0.28, and the wear rate is 9.6mm / 10000km.

[0045] The carbon fibers in the Cf / copper-based composite material are unevenly dispersed, have a high porosity, a high friction coefficient, and insufficient wear resistance.

[0046] Comparative Example 2

[0047] Add multi-walled CNT (aspect ratio of about 50-200:1) to water, ultrasonically treat to evenly disperse the CNT, then filter and dry for use; mix copper powder: nickel powder: chromium powder at 100:2:1, add multi-walled CNT, ball mill (60-240min, speed 20-45n / min) and evenly mix. Transfer the mixed powder into a mold for molding (300-500MPa) to prepare a cold billet. Put the cold billet into a sintering furnace, the sintering temperature is 850-950℃, keep warm for 5-60min, and use hydrogen as a protective gas. After cooling, a CNT / copper-based composite material is obtained.

[0048] The CNT in the CNT copper-based composite material has a large aspect ratio and is very easy to agglomerate and break during the ball milling process. The CNT content in the Cf / copper-based composite material is about 0.5 vol%, and the porosity is 5.7%. The impact strength of the composite material is 2.8 kj / m 2 , hardness is 77HRB, conductivity is 34.7%AICS. Under the conditions of 50A, speed 100km / h, load 90N, the friction coefficient of the composite material is 0.34, and the wear rate is 15.5mm / 10000km. The CNT in the CNT / copper-based composite material is unevenly dispersed, the friction coefficient is high, and the wear resistance is poor.

[0049] Comparative Example 3

[0050] The pitch-based carbon fiber with a length of 10 mm was placed in a deposition furnace, and a pyrolytic carbon layer was deposited by CVI to fix the short carbon fiber structure. Finally, it was transferred to a graphitization furnace, heated to 2000°C, and kept at this temperature for 1.5 hours for graphitization treatment.

[0051] Copper powder: nickel powder: chromium powder are mixed in a ratio of 100:2:1, and evenly mixed after ball milling. The copper alloy mixed powder is covered on the chopped carbon fiber preform, and transferred to the sintering furnace; vacuum is evacuated, heated to 1200℃, and kept warm for 30 minutes; N2 is used as a protective gas, 5MPa pressure is added, and the temperature is kept and pressure is maintained for 30 minutes, and the Cf / copper-based composite material is obtained after cooling.

[0052] The carbon fiber content of the Cf / copper matrix composite is about 15.2 vol%, the degree of graphitization is 20.3%, and the porosity is 6.5%. The impact strength of the composite is 2.5 kj / m 2 , hardness is 70HRB, conductivity is 31.9%AICS. Under the conditions of 50A, speed 100km / h, load 90N, the friction coefficient of the composite material is 0.19, and the wear rate is 3.77mm / 10000km.

[0053] Comparative Example 4

[0054] Asphalt-based carbon fibers with lengths of 20 mm, 10 mm, and 5 mm were mixed in a ratio of 1:2:1. Finally, they were transferred to a graphitization furnace, heated to 2000°C, and kept warm for 1.5 hours for graphitization treatment.

[0055] Copper powder: nickel powder: chromium powder are mixed in a ratio of 100:2:1, and evenly mixed after ball milling. The copper alloy mixed powder is covered on the chopped carbon fiber preform, and transferred to the sintering furnace; vacuum is evacuated, heated to 1200℃, and kept warm for 30 minutes; N2 is used as a protective gas, 5MPa pressure is added, and the temperature is kept and pressure is maintained for 30 minutes, and the Cf / copper-based composite material is obtained after cooling.

[0056] The carbon fiber content of the Cf / copper matrix composite is about 19.9 vol%, the degree of graphitization is 20.3%, and the porosity is 5.7%. The impact strength of the composite is 2.9 kj / m 2 , hardness is 68HRB, conductivity is 32.3%AICS. Under the conditions of 50A, speed 100km / h, load 90N, the friction coefficient of the composite material is 0.181, and the wear rate is 3.65mm / 10000km.

[0057] Comparative Example 5

[0058] Asphalt-based carbon fibers with lengths of 20 mm, 10 mm, and 5 mm were mixed in a ratio of 1:2:1; the short carbon fiber structure was fixed by CVI deposition of pyrolytic carbon layer. The CVI process conditions were: temperature of 980 ° C, pressure of 1000 Pa; carbon source C3H6 gas flow rate of 2 L / min, dilution gas N2 flow rate of 4 L / min; deposition time of 100 h. Then graphitization treatment was performed, the temperature was raised to the required temperature (2000 ° C), and the temperature was kept for 1 h to obtain a Cf / C preform.

[0059] Copper powder: nickel powder: chromium powder are mixed in a ratio of 100:2:1, and evenly mixed after ball milling. The copper alloy mixed powder is covered on the chopped carbon fiber preform, and transferred to the sintering furnace; vacuum is evacuated, heated to 1200℃, and kept warm for 30 minutes; N2 is used as a protective gas, 5MPa pressure is added, and the temperature is kept and pressure is maintained for 30 minutes, and the Cf / copper-based composite material is obtained after cooling.

[0060] The carbon fiber content of the Cf / copper matrix composite is about 21.5 vol%, the pyrolytic carbon thickness is 2.88 μm, the graphitization degree is 25.4%, and the porosity is 2.47%. The impact strength of the composite is 4.0 kj / m 2 , hardness is 74HRB, conductivity is 43.8%AICS. Under the conditions of 50A, speed 100km / h, load 90N, the friction coefficient of the composite material is 0.155, and the wear rate is 1.69mm / 10000km.

[0061] Example 1

[0062] Asphalt-based carbon fibers with lengths of 20mm, 10mm, and 5mm are mixed in a ratio of 1:2:1. CVI deposits a pyrolytic carbon layer to fix the short carbon fiber structure. The CVI process conditions are: temperature of 980°C, pressure of 1000Pa; carbon source C3H6 gas flow rate of 2L / min, dilution gas N2 flow rate of 4L / min; deposition time of 100h. CVD deposits long carbon nanotubes, and the electroplated nickel layer provides a catalyst for CNT preparation. The electroplating current is 12A, the plating solution is 12wt% Ni4SO4, and the electroplating time is 5h; the nickel-plated sample is transferred to the deposition furnace, and CVD grows CNT. The CVD process conditions are: temperature of 850°C, pressure of 100Pa; carbon source C3H6 gas flow rate of 100cm 3 / min, the dilution gas N2 flow rate is 200cm 3 / min, the reducing gas H2 flow rate is 180cm 3 / min, deposition time is 3h. Then graphitization treatment is carried out, heating to the required temperature (2500℃), and keeping the temperature for 1h. The CNT-Cf preform is obtained, such as Figure 3 shown.

[0063] Copper powder: nickel powder: chromium powder are mixed in a ratio of 100:2:1, and evenly mixed after ball milling. The copper alloy mixed powder is covered on the chopped carbon fiber preform, and transferred to the sintering furnace; vacuum is evacuated, heated to 1200℃, and kept warm for 30 minutes; N2 is passed as a protective gas, 5MPa pressure is added, and the temperature is kept and pressure is maintained for 30 minutes, and the CNT-Cf / copper-based composite material is obtained after cooling.

[0064] The carbon fiber content of CNT-Cf / copper-based composite material is about 22.8 vol%, the thickness of pyrolytic carbon is 3.03 μm, the CNT content is about 1.5 vol%, the degree of graphitization is 81.7%, and the porosity is 2.39%. The impact strength of the composite material is 4.8 kj / m 2 , hardness is 75HRB, conductivity is 51.4%AICS. Under the conditions of 50A, speed 100km / h, load 90N, the friction coefficient of the composite material is 0.11, the wear rate is 1.13mm / 10000km, and all indicators meet the requirements of modern electric locomotive skateboards.

[0065] Example 2

[0066] Asphalt-based carbon fibers with lengths of 20mm, 10mm, and 5mm are mixed in a ratio of 1:2:1. CVI deposits a pyrolytic carbon layer to fix the short carbon fiber structure. The CVI process conditions are: temperature of 980°C, pressure of 1000Pa; carbon source C3H6 gas flow rate of 2L / min, dilution gas N2 flow rate of 4L / min; deposition time of 150h. CVD deposits long carbon nanotubes, and the electroplated nickel layer provides a catalyst for CNT preparation. The electroplating current is 12A, the plating solution is 12wt% Ni4SO4, and the electroplating time is 6h; the nickel-plated sample is transferred to the deposition furnace, and CVD grows CNT. The CVD process conditions are: temperature of 850°C, pressure of 100Pa; carbon source C3H6 gas flow rate of 100cm 3 / min, the dilution gas N2 flow rate is 200cm 3 / min, the reducing gas H2 flow rate is 180cm 3 / min, the deposition time is 4h. Then graphitization treatment is carried out, the temperature is raised to the required temperature (2500℃), and the temperature is kept for 1h to obtain a CNT-Cf preform.

[0067] Copper powder: nickel powder: chromium powder are mixed in a ratio of 100:2:1, and evenly mixed after ball milling. The copper alloy mixed powder is covered on the chopped carbon fiber preform, and transferred to the sintering furnace; vacuum is evacuated, heated to 1200℃, and kept warm for 30 minutes; N2 is passed as a protective gas, 5MPa pressure is added, and the temperature is kept and pressure is maintained for 30 minutes, and the CNT-Cf / copper-based composite material is obtained after cooling.

[0068] The carbon fiber content of CNT-Cf / copper matrix composite material is about 25.3vol%, the pyrolytic carbon thickness is 25.58μm, the CNT content is about 2.1vol%, the graphitization degree is 94.5%, and the porosity is 4.41%. The impact strength of the composite material is 4.37kj / m 2 , hardness is 73HRB, conductivity is 42.9%AICS. Under the conditions of 50A, speed 100km / h, load 90N, the friction coefficient of the composite material is 0.09, the wear rate is 1.55mm / 10000km, and all indicators meet the requirements of modern electric locomotive skateboards.

[0069] Example 3

[0070] PAN-based carbon fibers with lengths of 20mm, 10mm, and 5mm were mixed in a ratio of 1:2:1. CVI deposited a pyrolytic carbon layer to fix the short carbon fiber structure. The CVI process conditions were: temperature of 980°C, pressure of 1000Pa; carbon source C3H6 gas flow rate of 2L / min, dilution gas N2 flow rate of 4L / min; deposition time of 150h. CVD deposited long carbon nanotubes, electroplated nickel layer provided catalyst for CNT preparation, electroplating current of 12A, plating solution of 12wt% Ni4SO4, electroplating time of 6h; the nickel-plated sample was transferred to the deposition furnace, and CNT was grown by CVD. The CVD process conditions were: temperature of 850°C, pressure of 100Pa; carbon source C3H6 gas flow rate of 80cm 3 / min, the dilution gas N2 flow rate is 240cm 3 / min, the reducing gas H2 flow rate is 160cm 3 / min, the deposition time is 4h. Then graphitization treatment is carried out, the temperature is raised to the required temperature (2500℃), and the temperature is kept for 1h to obtain a CNT-Cf preform.

[0071] Copper powder: nickel powder: chromium powder are mixed in a ratio of 100:2:1, and evenly mixed after ball milling. The copper alloy mixed powder is covered on the chopped carbon fiber preform, and transferred to the sintering furnace; vacuum is evacuated, heated to 1200℃, and kept warm for 30 minutes; N2 is passed as a protective gas, 5MPa pressure is added, and the temperature is kept and pressure is maintained for 30 minutes, and the CNT-Cf / copper-based composite material is obtained after cooling.

[0072] The carbon fiber content of CNT-Cf / copper matrix composite material is about 26.1vol%, the pyrolytic carbon thickness is 19.55μm, the CNT content is about 2.1vol%, the graphitization degree is 34.7%, and the porosity is 3.87%. The impact strength of the composite material is 4.52kj / m 2, hardness is 77HRB, conductivity is 46.3%AICS. Under the conditions of 50A, speed 100km / h, load 90N, the friction coefficient of the composite material is 0.14, the wear rate is 2.87mm / 10000km, and all indicators meet the requirements of modern electric locomotive skateboards.

[0073] Example 4

[0074] Asphalt-based carbon fibers with lengths of 20mm, 10mm, and 5mm are mixed in a ratio of 1:2:1. CVI deposits a pyrolytic carbon layer to fix the short carbon fiber structure. The CVI process conditions are: temperature of 980°C, pressure of 1000Pa; carbon source C3H6 gas flow rate of 2L / min, dilution gas N2 flow rate of 4L / min; deposition time of 150h. CVD deposits long carbon nanotubes, and the electroplated nickel layer provides a catalyst for CNT preparation. The electroplating current is 12A, the plating solution is 12wt% Ni4SO4, and the electroplating time is 6h; the nickel-plated sample is transferred to the deposition furnace, and CVD grows CNT. The CVD process conditions are: temperature of 850°C, pressure of 100Pa; carbon source C3H6 gas flow rate of 100cm 3 / min, the dilution gas N2 flow rate is 300cm 3 / min, the reducing gas H2 flow rate is 200cm 3 / min, the deposition time is 5h. Then graphitization treatment is carried out, the temperature is raised to the required temperature (2500℃), and the temperature is kept for 1h to obtain a CNT-Cf preform.

[0075] Copper powder: nickel powder: chromium powder: tin powder are mixed in a ratio of 100:2:1:1, and evenly mixed after ball milling. The copper alloy mixed powder is covered on the chopped carbon fiber preform, and transferred to the sintering furnace; vacuum is evacuated, heated to 1200℃, and kept warm for 30 minutes; N2 is passed as a protective gas, 5MPa pressure is added, and the temperature is kept and pressure is maintained for 30 minutes, and the CNT-Cf / copper-based composite material is obtained after cooling.

[0076] The carbon fiber content of CNT-Cf / copper-based composite material is about 21.8 vol%, the thickness of pyrolytic carbon is 22.89 μm, the CNT content is about 2.45 vol%, the degree of graphitization is 91.9%, and the porosity is 2.98%. The impact strength of the composite material is 4.68 kj / m 2 , hardness is 77HRB, conductivity is 49.2%AICS. Under the conditions of 50A, speed 100km / h, load 90N, the friction coefficient of the composite material is 0.08, the wear rate is 1.05mm / 10000km, and all indicators meet the requirements of modern electric locomotive skateboards.

[0077] Example 5

[0078] Asphalt-based carbon fibers with lengths of 20mm, 10mm, and 5mm are mixed in a ratio of 1:2:1. CVI deposits a pyrolytic carbon layer to fix the short carbon fiber structure. The CVI process conditions are: temperature of 980°C, pressure of 1000Pa; carbon source C3H6 gas flow rate of 2L / min, dilution gas N2 flow rate of 4L / min; deposition time of 50h. CVD deposits long carbon nanotubes, and the electroplated nickel layer provides a catalyst for CNT preparation. The electroplating current is 12A, the plating solution is 12wt% Ni4SO4, and the electroplating time is 6h; the nickel-plated sample is transferred to the deposition furnace, and CNT is grown by CVD. The CVD process conditions are: temperature of 850°C, pressure of 100Pa; carbon source C3H6 gas flow rate of 60cm 3 / min, the dilution gas N2 flow rate is 200cm 3 / min, the reducing gas H2 flow rate is 200cm 3 / min, the deposition time is 7h. Then graphitization treatment is carried out, the temperature is raised to the required temperature (2500℃), and the temperature is kept for 1h to obtain a CNT-Cf preform.

[0079] Copper powder: nickel powder: chromium powder: tin powder are mixed in a ratio of 100:2:1:1, and evenly mixed after ball milling. The copper alloy mixed powder is covered on the chopped carbon fiber preform, and transferred to the sintering furnace; vacuum is evacuated, heated to 1200℃, and kept warm for 30 minutes; N2 is passed as a protective gas, 5MPa pressure is added, and the temperature is kept and pressure is maintained for 30 minutes, and the CNT-Cf / copper-based composite material is obtained after cooling.

[0080] The carbon fiber content of CNT-Cf / copper matrix composite material is about 20.3vol%, the pyrolytic carbon thickness is 5.71μm, the CNT content is about 2.8vol%, the graphitization degree is 85.8%, and the porosity is 1.98%. The impact strength of the composite material is 5.15kj / m 2 , hardness is 80HRB, conductivity is 55.6%AICS. Under the conditions of 50A, speed 100km / h, load 90N, the friction coefficient of the composite material is 0.11, the wear rate is 1.25mm / 10000km, and all indicators meet the requirements of modern electric locomotive skateboards.

Claims

1. A three-dimensional network carbon phase reinforced copper-based composite material, characterized in that: The composite material comprises short carbon fibers, carbon nanotubes, and a matrix, wherein the matrix is ​​copper or a copper alloy; wherein the short carbon fibers and the carbon nanotubes are distributed in the copper and / or copper alloy matrix, the short carbon fibers serve as a primary reinforcement, the carbon nanotubes serve as a secondary reinforcement, and all or part of the carbon nanotubes are fixed on the short carbon fibers by in-situ growth; The short carbon fibers are composed of chopped carbon fibers of different lengths, wherein the length of the short carbon fibers is less than or equal to 100 mm; the chopped carbon fibers of different lengths include carbon fibers with a length of 15 to 20 mm, carbon fibers with a length of 6.5 to 13.5 mm, and carbon fibers with a length of 4.5 to 5.5 mm; The carbon fiber with a length of 15-20 mm, the carbon fiber with a length of 6.5-13.5 mm, and the carbon fiber with a length of 4.5-5.5 mm are composed in a mass ratio of A:B:C, wherein A and C are less than B; A is equal to 0.4-0.6 times B, and C is equal to 0.4-0.6 times B.

2. The three-dimensional network carbon phase reinforced copper-based composite material according to claim 1, characterized in that: The length of the short carbon fibers is less than or equal to 30 mm.

3. The three-dimensional network carbon phase reinforced copper-based composite material according to claim 1, characterized in that: The length of the short carbon fibers is less than or equal to 20 mm.

4. The three-dimensional network carbon phase reinforced copper-based composite material according to claim 1, characterized in that: The mass of the carbon nanotubes is 1-20% of the mass of the short carbon fibers; in the three-dimensional network carbon phase reinforced copper-based composite material, the total mass of the carbon nanotubes and the short carbon fibers accounts for 5-40% of the volume of the three-dimensional network carbon phase reinforced copper-based composite material.

5. The three-dimensional network carbon phase reinforced copper-based composite material according to claim 4, characterized in that: The mass of carbon nanotubes is 6.5-13.5% of the mass of short carbon fibers; In the three-dimensional network carbon phase reinforced copper-based composite material, the total mass of the carbon nanotubes and the short carbon fibers accounts for 23-28% of the volume of the three-dimensional network carbon phase reinforced copper-based composite material.

6. A method for preparing a three-dimensional network carbon phase reinforced copper-based composite material as claimed in any one of claims 1 to 5, characterized in that The steps include: Step A According to the components involved, short carbon fibers of different lengths are selected; then carbon nanotubes are deposited on the short carbon fibers to obtain CNT-Cf; Step B The powder with the nominal composition of the copper matrix design component is covered on the CNT-Cf; Or the CNT-Cf is embedded in a powder with a nominal composition of the copper matrix design component, and sintered to obtain a product; the sintering temperature is greater than or equal to the melting temperature of the powder.

7. The method for preparing a three-dimensional network carbon phase reinforced copper-based composite material according to claim 6, characterized in that: In step A, a short carbon fiber porous body is obtained by pressing; then pyrolytic carbon is deposited on the short carbon fiber porous body by a CVI process to obtain a short carbon fiber porous body with pyrolytic carbon, and then carbon nanotubes are in situ generated on the short carbon fiber porous body with pyrolytic carbon by a chemical vapor deposition process; The CVI process conditions used are: temperature 850-1150°C, pressure 800-1200Pa; carbon source C3H6 gas flow rate 1-3L / min, dilution gas N2 flow rate 2-6L / min; deposition time 50-300 h; When carbon nanotubes are grown in situ on a porous body of short carbon fibers with pyrolytic carbon by chemical vapor deposition, the following process is used: First, the electroplating nickel layer provides a catalyst for CNT preparation. The electroplating current is 9-16A, the plating solution is 9-16wt% Ni4SO4, and the electroplating time is 4-7h. The nickel-plated sample is transferred to a deposition furnace, and then CVD grows CNT. The CVD process conditions are: temperature 700-1100℃, pressure 1-500Pa; carbon source C3H6 gas flow rate is 50-110 cm 3 / min, the dilution gas N2 flow rate is 150-450 cm 3 / min, the reducing gas H2 flow rate is 150-250 cm 3 / min; the morphology of CNT is regulated by controlling the gas flow rate, and the diameter and length of CNT are regulated by controlling the deposition temperature and time; finally, graphitization treatment is performed, the carbon fiber includes asphalt-based carbon fiber and polyacrylonitrile-based carbon fiber, and the size of the chopped carbon fiber includes 0.5mm-100mm; the temperature is raised to 1600-2800℃ and kept warm for 30min-5h.

8. The method for preparing a three-dimensional network carbon phase reinforced copper-based composite material according to claim 6, characterized in that: The copper content in the copper matrix is ​​greater than 95wt%; the copper matrix contains copper, nickel and chromium, and the ratio of copper: nickel: chromium is 100~102: 1.8-2.2: 0.8-1.

2.

9. The method for preparing a three-dimensional network carbon phase reinforced copper-based composite material according to claim 8, characterized in that: The copper matrix contains other metal elements M, and the mass ratio of M to copper is copper:M=100~102:08~1.2; and M is selected from at least one of tin, zirconium, tungsten, titanium, silicon, lead, molybdenum, aluminum, and iron.

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