Preparation method of Cu-Ti-graphene composite material with layered gradient structure

Abstract

The invention discloses a preparation method of a Cu-Ti-graphene composite material with a layered gradient structure. The preparation method comprises the following steps: (1) powder pretreatment; (2) preparing a graphene mixed powder sample; (3) high-temperature reduction; (4) pressing and sintering the powder sample layer by layer; and (5) vacuum hot pressed sintering. The graphene nanoplatelets are added, high conductivity is reserved, and meanwhile the heat conduction performance and the mechanical performance of the copper-based alloy are enhanced; before the pure copper and the graphene microchip are mixed, Ti powder and the pure copper are added for ball-milling mixing, so that the Cu / C wettability is improved, and the strength of the composite material is enhanced; through mechanical mixing, the copper-titanium graphene powder is mixed more uniformly, and the performance is more excellent; a Cu-Ti-graphene sample is pressed in a layered mode through the layered gradient structure, the Ti element is fully diffused on a Cu / C interface, and a better strengthening effect is achieved; the Cu-Ti-graphene composite material which is excellent in density, heat conduction, electric conduction and mechanical properties and wider in application is prepared through vacuum hot pressing sintering and alloy grain size refinement.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of copper-based thermal conductive materials, and particularly relates to a method for preparing a layered gradient structure Cu-Ti-graphene composite material. Background Art

[0002] Copper-based alloys are widely used in various electronic component fields due to their excellent electrical properties. However, with the progress of the times, the poor thermal conductivity and mechanical properties of copper-based alloys cannot meet a wider range of applications. At present, there is a great demand for electronic packaging materials with high electrical conductivity and high thermal conductivity. To meet this demand, it is necessary to improve the thermal conductivity and mechanical properties of copper-based alloys while maintaining their high electrical conductivity.

[0003] Graphene is composed of a single layer to several layers of covalently bonded sp2 carbon atoms, in which the carbon atoms are arranged in a six-ring structure. Such a unique and stable structure endows graphene with a high tensile elastic modulus (1 TPa), tensile strength (130 GPa), and thermal conductivity (5000 Wm -1 K -1 ), zero bandgap, and high electron-hole mobility. Among them, the electron mobility can reach 15000 cm 2 / (v.s), and its resistivity reaches 10 -6 Ω·cm, which is the material with the smallest resistivity in the world at present. When an external mechanical force is applied, the carbon atom layer will bend and deform to adapt to the external force without having to rearrange the carbon atoms, thus maintaining the stability of the structure. Its high electrical conductivity, self-stability, and nano-layer structure determine that graphene can be used as a high-performance thermal conductive and conductive material. Therefore, using nano-graphene microplates to strengthen the copper matrix is a feasible and effective method.

[0004] At present, the preparation technologies for strengthening copper matrix with nano-graphene microplates mainly include powder metallurgy method, vacuum hot pressing sintering method, pressureless sintering method, high-energy mechanical grinding method, etc. However, these methods have characteristic defects: in the powder metallurgy method, the poor intrinsic wettability at the Cu / C interface limits the graphene strengthening effect, manifested as insufficient interfacial bonding strength and decreased thermal and electrical conductivity; in the pressureless sintering method, due to the lack of external pressure drive, problems such as insufficient material density and increased porosity are likely to occur; while in the vacuum hot pressing sintering method and high-energy mechanical grinding process, due to the influence of high-temperature sintering or severe mechanical action, abnormal grain growth of the copper matrix often occurs. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing a layered gradient structure Cu-Ti-graphene composite material, which simplifies the preparation process of the product, gives full play to the diffusion effect of Ti element at the Cu / C interface, and enhances the thermal conductivity and mechanical properties of the Cu-Ti-graphene composite material while retaining its high electrical conductivity.

[0006] To achieve the above object, the present invention uses the following technical solutions:

[0007] A preparation method of a layered gradient structure Cu-Ti-graphene composite material specifically includes the following steps:

[0008] (1) Powder pretreatment

[0009] Weigh high-purity Cu powder and Ti powder respectively and load them into the ball milling tank in sequence, add hard alloy balls, place the ball milling tank in a vacuum glove box with an argon atmosphere for assembly, take out the ball milling tank after assembly is completed, and fix it in a planetary ball mill for ball milling;

[0010] (2) Preparation of graphene mixed powder sample

[0011] Take two beakers and pour deionized water into them respectively. Take an appropriate amount of sodium dodecylbenzenesulfonate (SDBS) and dissolve it in deionized water, and stir until completely dissolved; take different amounts of nano-graphene microplates in the two beakers and label them 1 and 2, place the beakers in an ice-water bath ultrasonic cleaner for ultrasonic treatment to make them evenly dispersed in the solution, and obtain graphene suspensions; weigh an appropriate amount of the powder after ball milling in step (1) and place it in the graphene suspension, then add a dispersant, carry out mechanical stirring, and then place the beaker in an ultrasonic cleaner for ultrasonic treatment to make them fully mixed and uniform;

[0012] (3) High-temperature reduction

[0013] Take out the beaker after ultrasonic treatment in step (2), put it into a drying oven for drying, grind the dried powder evenly and spread it on a ceramic boat, then put it into a tube furnace, set the program and carry out reduction treatment in a hydrogen atmosphere, and finally obtain Cu-Ti-graphene composite powder;

[0014] (4) Layered pressing and sintering of powder samples

[0015] Weigh an appropriate amount of the copper-titanium mixed powder after ball milling in step (1), spread it flat in a graphite mold for pre-compaction, continue to add the reduced No. 1 Cu-Ti-graphene composite powder after grinding in step (3) on the surface of the specimen, spread it flat again for pre-compaction, and finally add the reduced No. 2 Cu-Ti-graphene composite powder after grinding in step (3) for pre-compaction treatment;

[0016] (5) Vacuum hot pressing and sintering

[0017] Place the graphite mold pretreated in step (4) in the furnace cavity of a vacuum hot pressing sintering furnace, set the program to vacuum the furnace cavity, and then carry out sintering. After sintering is completed, a Cu-Ti-graphene composite material is obtained.

[0018] Preferably, in the laminated gradient structure Cu-Ti-graphene composite material, the mass fraction of Ti powder is 0.5-1.5%, the volume fractions of nano-graphene micro-sheets are 10% and 20% respectively, and the rest is high-purity Cu powder. The Cu powder is high-purity electrolytic Cu powder, in the shape of grape clusters, with a purity of 99.999%, a particle size of 1-3 μm, the purity of Ti powder is 99.99%, the particle size is larger than 300 mesh, the thickness of the nano-graphene micro-sheet is 6-8 nm, the width is 15 μm, and the specific surface area reference value is 132.4 m 2 / g.

[0019] Preferably, in the step (1), the planetary ball mill is a QM-QX4 all-round planetary ball mill, the ball milling speed is 200 rpm, the ball-to-material ratio is 5:1, the ball milling time is 8 h, and both the ball tank and the ball milling medium balls are made of cemented carbide.

[0020] Preferably, when sodium dodecylbenzenesulfonate (SDBS) is dissolved in deionized water in the step (2), the mass percentage of sodium dodecylbenzenesulfonate (SDBS) is 0.5 wt%-2.0 wt%.

[0021] Preferably, when mechanical stirring and ultrasonic treatment are carried out in the step (2), the ultrasonic cleaner used is a JK-5200B type ultrasonic cleaner, with a power of 200 W and a frequency of 40 KHz; in addition to an appropriate amount of SDBS mixed solution in the beaker, sodium dodecylbenzoate is also added as a dispersant, and its addition amount is determined according to the dispersion of the mixed powder to promote more uniform dispersion of the powder.

[0022] Preferably, the model of the drying oven in the step (3) is DHG-9000-9005, the drying temperature is 50-60 °C, and the drying time is 12 h.

[0023] Preferably, the model of the tube furnace in the step (3) is GSL-1200X, and the set program is to heat from room temperature to 200 °C at a rate of 10 °C / min, hold for 2 h, and then cool to room temperature with the furnace.

[0024] Preferably, the gas introduced in the step (3) is 10% H2-90% Ar, and the introduction amount is 300-350 ml / min.

[0025] Preferably, in the step (4), the inner diameter of the graphite mold is 20 mm, the outer diameter is 60 mm, and the height is 70 mm. Carbon paper is used to isolate the Cu-Ti-graphene composite powder from the graphite mold, which is convenient for sampling and demolding after sintering.

[0026] Preferably, in the step (5), the model of the vacuum hot-pressing sintering furnace is GSL-2000X-HV, and a thermocouple is used for temperature measurement. The front end of the thermocouple is inserted into the temperature measurement hole of the graphite mold. The vacuum hot-pressing sintering setting program is as follows: heating from room temperature to 920 °C at a heating rate of 10 °C / min, keeping the temperature for 1 h under a pressure of 50 MPa, and then cooling with the furnace.

[0027] The innovation of the present invention lies in:

[0028] In terms of material design: By mixing Cu powder, Ti powder, and nano-graphene micro-sheets in a certain proportion, making full use of Ti to form a carbide layer, significantly improving the wettability of Cu / C, increasing the relative density and thermal conductivity, and also fully utilizing the properties of nano-graphene micro-sheets such as high thermal conductivity, good electrical conductivity, self-stability, and nano-layer structure to achieve the strengthening effect on the copper matrix; By constructing a layered gradient structure and laminating the Cu-Ti-graphene sample, realizing the full diffusion of Ti elements at the Cu / C interface and strengthening the interfacial bonding performance of Cu / C.

[0029] In terms of the preparation method: The preparation method of the present invention consists of ball milling, drying, reduction, mechanical stirring, ultrasonic treatment, and vacuum hot-pressing sintering processes. The process flow is relatively simple, and the operation process is easy. At the same time, these processes enable the material to have a specific crystal structure and phase composition, thereby improving the performance of the material. This preparation method provides the possibility for large-scale production of this high-performance thermally and electrically conductive material.

[0030] In terms of performance optimization: By using nano-graphene micro-sheets and the method of laminating the Cu-Ti-graphene with a layered gradient structure to enhance the copper-based composite material, further improving the thermal conductivity and mechanical properties of the copper-based alloy, showing excellent overall performance.

[0031] Compared with the existing process technologies, the present invention has at least the following beneficial effects:

[0032] The present invention adds nanographene microsheets, which have high Young's modulus, high fracture strength and extremely high thermal conductivity / electrical conductivity, and enhance the thermal conductivity and mechanical properties of the copper-based alloy while retaining high electrical conductivity. When a single nanographene microsheet is incorporated into a copper-based composite material, the inherent poor wettability of Cu / C limits the strength effect of the graphene. Before mixing pure copper and nanographene microsheets, the present invention adds Ti powder and pure copper for ball milling, because the carbide (such as TiC) layer can effectively enhance the interface bonding strength, improve the wettability of Cu / C, and further enhance the strength of the composite material. Mechanical Compared with directly adding graphene to copper-titanium powder during ball milling, the method of mixing nano-graphene flakes and copper-titanium powder can better retain the atomic structural characteristics of graphene, making the obtained copper-titanium graphene powder more evenly mixed and having better performance in all aspects; the Cu-Ti-graphene sample is pressed in layers with a layered gradient structure to achieve sufficient diffusion of the Ti element at the Cu / C interface, thereby achieving better strengthening effect; the grain size of the alloy is refined through the densification effect of vacuum hot pressing sintering, and finally a Cu-Ti-graphene composite material with superior density, thermal conductivity, electrical conductivity and mechanical properties and wider application is prepared. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the surface morphology of the Cu-1.5%Ti-graphene composite material powder in Example 3;

[0034] Figure 2 This is a high-magnification fracture morphology image of the Cu-1.5%Ti-graphene composite material in Example 3;

[0035] Figure 3 This is the interface morphology of the Cu-1.5%Ti-graphene composite material in Example 3;

[0036] Figure 4 This is the EDS analysis diagram of the Cu-1.5%Ti-graphene composite material in Example 3. DETAILED DESCRIPTION

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0038] Example 1

[0039] The Cu-graphene composite material in this embodiment is processed by ball milling, drying, reduction, mechanical stirring, ultrasonication and vacuum hot pressing sintering. The volume fractions of nanographene microplatelets are 10.0% and 20.0% respectively, and the rest is high-purity Cu powder. The Cu powder is high-purity electrolytic Cu powder, in the shape of grape bunches, with a purity of 99.999% and a particle size of 1-3 μm. The nanographene microplatelets are 6-8 nm thick and 15 μm wide, with a reference specific surface area of 132.4 m 2 / g.

[0040] In this embodiment, the preparation method of the Cu-graphene composite material is as follows:

[0041] (1) Powder pretreatment

[0042] Weigh 50 g of high-purity Cu powder, put it into a ball milling tank, add cemented carbide balls at a ball-to-material ratio of 5:1, place the ball milling tank in a vacuum glove box with an argon atmosphere for assembly, take out the ball milling tank after assembly, fix it in a planetary ball mill, set the rotation speed to 200 rpm, and ball mill for 8 h;

[0043] (2) Preparation of graphene mixed powder sample

[0044] Pour 100 ml of deionized water into two beakers and label them 1 and 2 respectively. Add 1 g of SDBS to the deionized water in each beaker and stir for 10 min to completely dissolve it in the deionized water; weigh 0.775 g of nano-graphene microplates into beaker No. 1, weigh 1.74 g of nano-graphene microplates into beaker No. 2, then place the beakers in an ice-water bath ultrasonic cleaner and ultrasonicate for 30 min to obtain graphene suspensions; weigh out 24.225 g of the ball-milled powder and place it in beaker No. 1, weigh out 23.26 g of the ball-milled powder and place it in beaker No. 2, then add 0.06 g of sodium dodecylbenzenesulfonate dispersant respectively, carry out mechanical stirring for 30 min, and then place the beakers in an ultrasonic cleaner and ultrasonicate for 30 min to make them fully mixed and uniform;

[0045] (3) High-temperature reduction

[0046] Take out the ultrasonically treated beakers in step (2), put them into a drying oven for drying treatment, the drying temperature is 50 - 60 °C, the drying time is 12 h, after drying, grind the obtained powder, spread it evenly on a ceramic boat, and then put it into a tube furnace, introduce a gas of 10% H2 - 90% Ar at a flow rate of 300 - 350 ml / min to create a reducing atmosphere, set the program to heat from room temperature to 200 °C at a rate of 10 °C / min, hold for 2 h, and then cool to room temperature with the furnace, finally obtaining Cu-Ti-graphene composite powder;

[0047] (4) Layered pressing and sintering of powder samples

[0048] Weigh 10 g of the ball-milled copper powder in step (1) and spread it evenly in a graphite mold (the inner diameter of the graphite mold is 20 mm, the outer diameter is 60 mm, and the height is 70 mm. A carbon paper is used to isolate the Cu-graphene composite powder from the graphite mold to facilitate sampling and demolding after sintering), and pre-compact it under a pressure of 5 MPa. Then, continue to add 10 g of the reduced 10% vol GN Cu-graphene composite powder in step (3) after grinding on the surface of the sample, spread it evenly again, and pre-compact it under a pressure of 5 MPa. Finally, add 10 g of the reduced 20% vol GN Cu-graphene composite powder in step (3) after grinding and pre-compact it under a pressure of 10 MPa, and hold the pressure for 15 s.

[0049] (5) Vacuum hot pressing sintering

[0050] Place the pre-pressed graphite mold into the furnace cavity of a vacuum hot pressing sintering furnace, and insert the front end of the thermocouple into the temperature measurement hole of the graphite mold; close the furnace cavity door for vacuum treatment. After the furnace cavity reaches the required vacuum level, sinter it according to the set program as follows: heat up from room temperature to 920 °C at a heating rate of 10 °C / min, hold for 1 h under a pressure of 50 MPa, and then cool down with the furnace. After sintering is completed, a Cu-graphene composite material is obtained.

[0051] Example 2

[0052] The Cu-Ti-graphene composite material in this example is processed by ball milling, drying, reduction, mechanical stirring, ultrasonic treatment, and vacuum hot pressing sintering processes. The mass fraction of Ti powder is 0.5%, the volume fractions of nano-graphene micro-sheets are 10.0% and 20.0% respectively, and the rest is high-purity Cu powder. The Cu powder is high-purity electrolytic Cu powder, in the shape of grape clusters, with a purity of 99.999%, a particle size of 1 - 3 μm, the purity of Ti powder is 99.99%, the particle size is larger than 300 mesh, the thickness of nano-graphene micro-sheets is 6 - 8 nm, the width is 15 μm, and the specific surface area reference value is 132.4 m 2 / g.

[0053] The preparation method of the Cu-Ti-graphene composite material in this example is as follows:

[0054] (1) Powder pretreatment

[0055] Weigh 49.75 g of high-purity Cu powder and 0.25 g of Ti powder respectively, put them into a ball milling tank, add cemented carbide balls with a ball-to-powder ratio of 5:1, assemble the ball milling tank in a vacuum glove box under an argon atmosphere, take out the ball milling tank after assembly, fix it in a planetary ball mill, set the rotation speed to 200 rpm, and ball mill for 8 h;

[0056] (2) Preparation of graphene mixed powder sample

[0057] Pour 100 ml of deionized water into two beakers respectively, label them as 1 and 2, add 1 g of SDBS to each beaker and dissolve it in deionized water, and stir for 10 min to completely dissolve it in deionized water; weigh 0.775 g of nano-graphene micro-sheets into beaker No. 1, weigh 1.74 g of nano-graphene micro-sheets into beaker No. 2, then place the beakers in an ice-water bath ultrasonic cleaner and ultrasonicate for 30 min to obtain graphene suspensions; weigh out 24.225 g of the ball-milled powder and place it in beaker No. 1, weigh out 23.26 g of the ball-milled powder and place it in beaker No. 2, then add 0.06 g of sodium dodecylbenzenesulfonate dispersant respectively, carry out mechanical stirring for 30 min, and then place the beakers in an ultrasonic cleaner and ultrasonicate for 30 min to make them fully mixed and uniform;

[0058] (3) High-temperature reduction

[0059] Take out the ultrasonically treated beakers in step (2), put them into a drying oven for drying treatment, the drying temperature is 50 - 60 °C, the drying time is 12 h, after drying, grind the obtained powder and spread it evenly on a ceramic boat and then put it into a tube furnace, and introduce a gas of 10% H2 - 90% Ar at a flow rate of 300 - 350 ml / min to create a reducing atmosphere, set the program to heat from room temperature to 200 °C at a rate of 10 °C / min, hold for 2 h, and then cool to room temperature with the furnace, and finally obtain Cu-Ti-graphene composite powder;

[0060] (4) Layered pressing and sintering of powder samples

[0061] Weigh 10 g of the copper-titanium mixed powder ball-milled in step (1) into a graphite mold (the inner diameter of the graphite mold is 20 mm, the outer diameter is 60 mm, and the height is 70 mm. Carbon paper is used to isolate between the Cu-Ti-graphene composite powder and the graphite mold to facilitate sampling and demolding after sintering), level it and pre-compact it at a pressure of 5 MPa. Continue to add 10 g of the ground Cu-Ti-graphene composite powder with 10% vol GN in No. 1 after reduction in step (3) on the surface of the specimen, level it again and pre-compact it at a pressure of 5 MPa. Finally, add 10 g of the ground Cu-Ti-graphene composite powder with 20% vol GN in No. 2 after reduction in step (3) and pre-compact it at a pressure of 10 MPa, and hold the pressure for 15 s;

[0062] (5) Vacuum hot pressing and sintering

[0063] Place the pre-pressed graphite mold described above in the furnace chamber of a vacuum hot-pressing sintering furnace, and insert the front end of the thermocouple into the temperature-measuring hole of the graphite mold; close the furnace chamber door for vacuum treatment, and after the furnace chamber reaches the required vacuum level, perform sintering according to the set program as follows: heat from room temperature to 920 °C at a heating rate of 10 °C / min, hold for 1 h under a pressure of 50 MPa, and then cool with the furnace. After sintering is completed, a Cu-Ti-graphene composite material is obtained.

[0064] Example 3

[0065] The Cu-Ti-graphene composite material in this example is processed by ball milling, drying, reduction, mechanical stirring, ultrasonic treatment, and vacuum hot-pressing sintering processes. Among them, the mass fraction of Ti powder is 1.5%, and the volume fractions of nano-graphene micro-sheets are 10.0% and 20.0% respectively, and the rest is high-purity Cu powder. The Cu powder is high-purity electrolytic Cu powder, in the shape of grape clusters, with a purity of 99.999%, a particle size of 1 - 3 μm, the purity of Ti powder is 99.99%, the particle size is larger than 300 mesh, the thickness of the nano-graphene micro-sheet is 6 - 8 nm, the width is 15 μm, and the specific surface area reference value is 132.4 m 2 / g.

[0066] The preparation method of the Cu-Ti-graphene composite material in this example is as follows:

[0067] (1) Powder pretreatment

[0068] Weigh 49.25 g of high-purity Cu powder and 0.75 g of Ti powder respectively, put them into a ball milling tank, add hard alloy balls at a ball-to-material ratio of 5:1, assemble the ball milling tank in a vacuum glove box under an argon atmosphere, take out the ball milling tank after assembly, fix it in a planetary ball mill, set the rotation speed to 200 rpm, and ball mill for 8 h;

[0069] (2) Preparation of graphene mixed powder sample

[0070] Pour 100 ml of deionized water into two beakers and label them 1 and 2 respectively. Add 1 g of SDBS to each beaker and dissolve it in deionized water by stirring for 10 min until it is completely dissolved in deionized water; weigh 0.775 g of nano-graphene micro-sheets into beaker No. 1 and 1.74 g of nano-graphene micro-sheets into beaker No. 2, then place the beakers in an ice-water bath ultrasonic cleaner and ultrasonicate for 30 min to obtain graphene suspensions; weigh out 24.225 g of the ball-milled powder and place it in beaker No. 1, weigh out 23.26 g of the ball-milled powder and place it in beaker No. 2, then add 0.06 g of sodium dodecylbenzenesulfonate dispersant respectively, stir mechanically for 30 min, and then place the beakers in an ultrasonic cleaner and ultrasonicate for 30 min to make them fully mixed and uniform;

[0071] (3) High-temperature reduction

[0072] Take out the beaker after ultrasonic treatment in step (2), put it into a drying oven for drying treatment. The drying temperature is 50 - 60 °C, and the drying time is 12 h. After drying, grind the obtained powder and evenly spread it on a ceramic boat, then put it into a tube furnace, and introduce a gas of 10% H₂ - 90% Ar at a flow rate of 300 - 350 ml / min to create a reducing atmosphere. Set the program to heat from room temperature to 200 °C at a rate of 10 °C / min, hold for 2 h, and then cool to room temperature with the furnace. Finally, obtain the Cu - Ti - graphene composite powder;

[0073] (4) Layered pressing and sintering of the powder sample

[0074] Weigh 10 g of the copper - titanium mixed powder after ball - milling in step (1) and spread it evenly in a graphite mold (the inner diameter of the graphite mold is 20 mm, the outer diameter is 60 mm, and the height is 70 mm. Carbon paper is used to isolate between the Cu - Ti - graphene composite powder and the graphite mold to facilitate sampling and demolding after sintering), and pre - compact it at a pressure of 5 MPa. Then, continue to add 10 g of the ground Cu - Ti - graphene composite powder with 10% vol GN No. 1 after reduction in step (3) on the surface of the sample, spread it evenly again, and pre - compact it at a pressure of 5 MPa. Finally, add 10 g of the ground Cu - Ti - graphene composite powder with 20% vol GN No. 2 after reduction in step (3) and pre - compact it at a pressure of 10 MPa for 15 s;

[0075] (5) Vacuum hot - pressing sintering

[0076] Place the above - mentioned pre - pressed graphite mold into the furnace cavity of a vacuum hot - pressing sintering furnace, and insert the front end of the thermocouple into the temperature - measuring hole of the graphite mold; close the furnace cavity door for vacuum treatment. After the furnace cavity reaches the required vacuum level, sinter according to the set program as follows: heat from room temperature to 920 °C at a heating rate of 10 °C / min, hold for 1 h under a pressure of 50 MPa, and then cool with the furnace. After sintering, obtain the Cu - Ti - graphene composite material.

[0077] Table 1 Performance table of bulk thermal conductivity, electrical conductivity, and flexural strength of Cu, Cu - graphene, Cu - 0.5% Ti - graphene, and Cu - 1.5% Ti - graphene

[0078]

[0079] From Figure 1 It can be seen that the powder presents a spherical shape, and the particle size is 20 - 25 μm.

[0080] From Figure 2It can be seen that the fracture surface of Cu-1.5%Ti-graphene presents an equiaxed dimple aggregation morphology as a whole; at the same time, it is found that the fracture surface is mainly composed of dimples and tear ridges inside the matrix, indicating that titanium elements enable graphene and copper matrix to deform synergistically and bear loads together by forming interfacial compounds or improving the interfacial bonding state, thus enhancing the overall plasticity and toughness of the material.

[0081] From Figure 3 , Figure 4 It can be seen that various element addition items can be found from the energy spectrum analysis, and Ti elements are evenly distributed between the Cu / C interfaces, proving that the full diffusion of Ti elements enhances the interfacial strength between Cu / C.

[0082] As can be seen from Table 1, compared with the copper-graphene alloy without titanium elements, the thermal conductivity and electrical conductivity of the material have been significantly improved after adding titanium elements; the flexural strength decreases slightly without adding titanium elements, while the flexural strength is significantly enhanced and the density is also significantly increased after adding titanium elements.

[0083] In the present invention, nano-graphene microplates are added. With their properties such as high Young's modulus, high fracture strength, and extremely high thermal / electrical conductivity, while retaining high electrical conductivity, the thermal conductivity and mechanical properties of the copper-based alloy are enhanced; when a single nano-graphene microplate is incorporated into the copper-based composite material, due to the poor inherent wettability of Cu / C, the strengthening effect of graphene is limited. In the present invention, before mixing pure copper and nano-graphene microplates, Ti powder is added and ball-milled with pure copper, because the carbide (such as TiC) layer can effectively enhance the interfacial bonding strength, improve the wettability of Cu / C, and further enhance the strength of the composite material; the method of mechanically mixing nano-graphene microplates and copper-titanium powder can better retain the atomic structure characteristics of graphene compared with directly adding graphene to the copper-titanium powder during ball milling, making the prepared copper-titanium-graphene powder mixture more uniform and having more excellent properties in all aspects; the Cu-Ti-graphene sample is pressed in a layered gradient structure to achieve the full diffusion of Ti elements at the Cu / C interface, so as to achieve a better strengthening effect; the grain size of the alloy is refined by the action of vacuum hot pressing sintering densification, and finally a Cu-Ti-graphene composite material with excellent density, thermal conductivity, electrical conductivity, mechanical properties and wider applications is prepared.

[0084] The above embodiments only illustrate the specific implementation schemes of the present disclosure, but the implementation schemes of the present disclosure are not limited to the above content. Any changes, modifications, substitutions, combinations, and simplifications made without substantially departing from the gist and principle of the inventive concept of the present disclosure shall be equivalent replacement methods and shall be included in the protection scope determined by the claims.

Claims

1. A preparation method of a layered gradient structure Cu-Ti-graphene composite material, characterized in that: Specifically, it includes the following steps: (1) Powder pretreatment Weigh high-purity Cu powder and Ti powder respectively and load them into the ball milling tank in sequence. Add cemented carbide balls. Place the ball milling tank in a vacuum glove box with an argon atmosphere for assembly. After the assembly is completed, take out the ball milling tank and fix it in a planetary ball mill for ball milling; (2) Preparation of graphene mixed powder sample Take two beakers and pour deionized water into them respectively. Dissolve an appropriate amount of sodium dodecylbenzenesulfonate (SDBS) in deionized water and stir until completely dissolved; Take different amounts of nano-graphene microplates in the two beakers and label them 1 and 2. Place the beakers in an ice-water bath ultrasonic cleaner for ultrasonic treatment to make them uniformly dispersed in the solution, obtaining a graphene suspension; Weigh an appropriate amount of the powder after ball milling in step (1) and place it in the graphene suspension. Then add a dispersant and conduct mechanical stirring. Then place the beaker in an ultrasonic cleaner for ultrasonic treatment to make them fully mixed and uniform; (3) High-temperature reduction Take out the beaker after ultrasonic treatment in step (2), put it into a drying oven for drying. Grind the dried powder evenly and spread it flat on a ceramic boat, then put it into a tube furnace. After setting the program, conduct reduction treatment in a hydrogen atmosphere, and finally obtain Cu-Ti-graphene composite powder; (4) Layered pressing and sintering of powder samples Weigh an appropriate amount of the copper-titanium mixed powder after ball milling in step (1), spread it flat in a graphite mold for pre-compaction. Continue to add the reduced No. 1 Cu-Ti-graphene composite powder after grinding in step (3) on the surface of the sample and spread it flat for pre-compaction. Finally, add the reduced No. 2 Cu-Ti-graphene composite powder after grinding in step (3) for pre-compaction treatment; (5) Vacuum hot pressing and sintering Place the graphite mold pretreated in step (4) into the furnace cavity of a vacuum hot pressing sintering furnace. After setting the program, conduct vacuum treatment on the furnace cavity, and then conduct sintering. After the sintering is completed, obtain a Cu-Ti-graphene composite material.

2. The preparation method of a layered gradient structure Cu-Ti-graphene composite material as claimed in claim 1, wherein: In the layered gradient structure Cu-Ti-graphene composite material, the mass fraction of Ti powder is 0.5-1.5%, the volume fractions of nano-graphene micro-sheets are 10% and 20% respectively, and the rest is high-purity Cu powder. The Cu powder is high-purity electrolytic Cu powder, showing a grape bunch shape, with a purity of 99.999%, a particle size of 1-3μm, the purity of Ti powder is 99.99%, the particle size is larger than 300 mesh, the thickness of the nano-graphene micro-sheet is 6-8nm, the width is 15μm, and the reference value of specific surface area is 132.4m 2 / g.

3. The preparation method of a layered gradient structure Cu-Ti-graphene composite material according to claim 1, characterized in that: In step (1), the planetary ball mill is a QM-QX4 all-round planetary ball mill, the ball milling speed is 200 rpm, the ball-to-material ratio is 5:1, the ball milling time is 8 h, and both the ball tank and the ball milling medium balls are made of cemented carbide.

4. The preparation method of a layered gradient structure Cu-Ti-graphene composite material according to claim 1, characterized in that: When sodium dodecylbenzenesulfonate (SDBS) is dissolved in deionized water in step (2), the mass percentage of sodium dodecylbenzenesulfonate (SDBS) is 0.5 wt%-2.0 wt%.

5. The preparation method of a layered gradient structure Cu-Ti-graphene composite material as described in claim 1, characterized in that: When conducting mechanical stirring and ultrasonic treatment in step (2), the ultrasonic cleaner used is a JK-5200B type ultrasonic cleaner, with a power of 200 W and a frequency of 40 KHz; In addition to an appropriate amount of SDBS mixed solution in the beaker, sodium dodecylbenzoate is also added as a dispersant, and its addition amount is determined according to the dispersion of the mixed powder to promote more uniform dispersion of the powder.

6. The preparation method of a layered gradient structure Cu-Ti-graphene composite material according to claim 1, characterized in that: In step (3), the model of the drying oven is DHG-9000-9005, the drying temperature is 50-60 °C, and the drying time is 12 h.

7. The preparation method of a layered gradient structure Cu-Ti-graphene composite material according to claim 1, characterized in that: In step (3), the model of the tube furnace is GSL-1200X. Set the program to heat from room temperature to 200 °C at a rate of 10 °C / min, hold for 2 h, and then cool to room temperature with the furnace.

8. The preparation method of a layered gradient structure Cu-Ti-graphene composite material as claimed in claim 1, characterized in that: The gas introduced in step (3) is 10% H2 - 90% Ar, and the flow rate is 300 - 350 ml / min.

9. The preparation method of a layered gradient structure Cu-Ti-graphene composite material as described in claim 1, characterized in that: In step (4), the inner diameter of the graphite mold is 20 mm, the outer diameter is 60 mm, and the height is 70 mm. Carbon paper is used to isolate the Cu-Ti-graphene composite powder from the graphite mold to facilitate sampling and demolding after sintering.

10. The preparation method of a layered gradient structure Cu-Ti-graphene composite material according to claim 1, characterized in that: In step (5), the vacuum hot pressing sintering furnace model is GSL-2000X-HV, and a thermocouple is used for temperature measurement. The front end of the thermocouple is inserted into the temperature measurement hole of the graphite mold. The vacuum hot pressing sintering setting program is as follows: heat up from room temperature to 920 °C at a heating rate of 10 °C / min, hold for 1 h under a pressure of 50 MPa, and then cool with the furnace.

Images