阅读说明：本技术 一种全碳导热复合材料及其制备方法 (All-carbon heat-conducting composite material and preparation method thereof ) 是由 冯奕钰 高龙 封伟 张飞 吕峰 于 2018-07-31 设计创作，主要内容包括：本发明公开一种全碳导热复合材料及其制备方法,通过膨胀石墨利用液相剥离制得石墨烯,接着通过等离子体增强化学气相沉积法生长垂直石墨烯,接着将其研磨成粉末,与中间相沥青粉末混合,经过热压,冷却。可得到全碳的导热复合材料,具有更好的导热性能和机械性能,所得到的材料的导热率可高达50W/(m·K),为碳功能材料的制备提出了新的方法,也扩宽了碳复合材料的应用范围。(The invention discloses an all-carbon heat-conducting composite material and a preparation method thereof. The obtained carbon-containing heat-conducting composite material has better heat-conducting property and mechanical property, the heat conductivity of the obtained material can reach 50W/(m.K), a new method is provided for preparing the carbon functional material, and the application range of the carbon composite material is widened.)

1. An all-carbon heat-conducting composite material is characterized by comprising the following steps:

step 1, performing liquid phase stripping by using expanded graphite to obtain graphene;

in the step 1, 0.1-0.5 part by mass of expanded graphite is uniformly dispersed in 100-150 parts by volume of N-methylpyrrolidone and reacted for 5-10 hours at 140-160 ℃ to obtain a graphene dispersion liquid; carrying out ultrasonic centrifugation on the obtained graphene dispersion liquid, taking supernatant, carrying out suction filtration to remove the NMP solvent, washing, carrying out ultrasonic treatment again to obtain a graphene solution, and carrying out freeze drying to obtain graphene powder;

step 2, vertically growing graphene on the surface of the graphene prepared in the step 1 by using a PECVD system;

in the step 2, putting the prepared graphene into a PECVD system device, vacuumizing the PECVD system device, heating the graphene to 500-700 ℃, introducing a carbon source gas, keeping the vacuum and heating state, turning on a plasma source to perform vertical growth of the graphene, naturally cooling to the room temperature of 20-25 ℃ to obtain a sample of the vertical graphene grown on the surface of the graphene, and introducing an inert protective gas as a protective gas all the time in the process;

step 3, mixing and stirring the sample of the graphene with the surface vertical to the surface of the graphene obtained in the step 2 and mesophase pitch, pressurizing and melting the mixture, and cooling the mixture to obtain the all-carbon heat-conducting composite material, wherein the heat conductivity can reach 45-50W/(m.K) along the axial direction of the material;

in step 3, the mass ratio of the mesophase pitch to the sample of the graphene with the surface growth vertical graphene obtained in step 2 is (5-12): 1, mixing and stirring the two materials, putting the mixture into a mould for pressurizing and melting, wherein the hot pressing pressure is 1-5 MPa, the hot pressing temperature is 800-1000 ℃, and the hot pressing time is 10-15 min.

2. The all-carbon heat-conducting composite material as claimed in claim 1, wherein in the step 1, the obtained graphene dispersion liquid is subjected to ultrasonic treatment for 10-30 min, then is centrifuged at 2000r/min for 10-15 min, the supernatant is taken, the NMP solvent is removed by suction filtration, the graphene solution is obtained by water washing and ultrasonic treatment, and the graphene powder is obtained by freeze drying.

3. The all-carbon heat-conducting composite material as claimed in claim 1, wherein in the step 3, the mass ratio of the mesophase pitch to the sample of the graphene surface-grown vertical graphene obtained in the step 2 is (8-12): 1; and (3) selecting mesophase pitch as a powder material, and grinding the sample of the graphene with the surface growing vertical to the graphene obtained in the step (2) into powder.

4. The all-carbon heat-conducting composite material as claimed in claim 1, wherein in the step 2, the carbon source gas is methane, ethane or ethanol, and the gas flow rate is 1000-1300 sccm; the inert protective gas is nitrogen, helium or argon, and the gas flow is 800-1000 sccm.

5. The all-carbon heat-conducting composite material as claimed in claim 1, wherein in the step 2, the graphene vertical growth is performed for 5-20 min, preferably 10-15 min, and the vacuum is maintained at 150-200 Pa.

6. The preparation method of the all-carbon heat-conducting composite material is characterized by comprising the following steps of:

step 1, performing liquid phase stripping by using expanded graphite to obtain graphene;

in the step 1, 0.1-0.5 part by mass of expanded graphite is uniformly dispersed in 100-150 parts by volume of N-methylpyrrolidone and reacted for 5-10 hours at 140-160 ℃ to obtain a graphene dispersion liquid; carrying out ultrasonic centrifugation on the obtained graphene dispersion liquid, taking supernatant, carrying out suction filtration to remove the NMP solvent, washing, carrying out ultrasonic treatment again to obtain a graphene solution, and carrying out freeze drying to obtain graphene powder;

step 2, vertically growing graphene on the surface of the graphene prepared in the step 1 by using a PECVD system;

in the step 2, putting the prepared graphene into a PECVD system device, vacuumizing the PECVD system device, heating the graphene to 500-700 ℃, introducing a carbon source gas, keeping the vacuum and heating state, turning on a plasma source to perform vertical growth of the graphene, naturally cooling to the room temperature of 20-25 ℃ to obtain a sample of the vertical graphene grown on the surface of the graphene, and introducing an inert protective gas as a protective gas all the time in the process;

step 3, mixing, stirring, pressurizing and melting the sample of the graphene with the surface vertical to the surface of the graphene obtained in the step 2 and the mesophase pitch, and cooling to obtain the all-carbon heat-conducting composite material;

in step 3, the mass ratio of the mesophase pitch to the sample of the graphene with the surface growth vertical graphene obtained in step 2 is (5-12): 1, mixing and stirring the two materials, putting the mixture into a mould for pressurizing and melting, wherein the hot pressing pressure is 1-5 MPa, the hot pressing temperature is 800-1000 ℃, and the hot pressing time is 10-15 min.

7. The preparation method of the all-carbon heat-conducting composite material according to claim 6, wherein in the step 1, the obtained graphene dispersion liquid is subjected to ultrasonic treatment for 10-30 min, then is centrifuged at 2000r/min for 10-15 min, the supernatant is taken, the NMP solvent is removed by suction filtration, the graphene solution is prepared by water washing and ultrasonic treatment, and the graphene powder is obtained by freeze drying.

8. The method for preparing an all-carbon heat-conducting composite material according to claim 6, wherein in the step 2, the carbon source gas is methane, ethane or ethanol, and the gas flow rate is 1000-1300 sccm; the inert protective gas is nitrogen, helium or argon, and the gas flow is 800-1000 sccm.

9. The method for preparing an all-carbon heat-conducting composite material according to claim 6, wherein in the step 2, the graphene vertical growth is performed for 5-20 min, preferably 10-15 min, and the vacuum is maintained at 150-200 Pa.

10. The preparation method of the all-carbon heat-conducting composite material as claimed in claim 6, wherein in the step 3, the mass ratio of the mesophase pitch to the sample of the graphene obtained in the step 2 with the surface growth of the vertical graphene is (8-12): 1; and (3) selecting mesophase pitch as a powder material, and grinding the sample of the graphene with the surface growing vertical to the graphene obtained in the step (2) into powder.

Technical Field

The invention belongs to the field of carbon functional composite materials, and particularly relates to an all-carbon heat-conducting composite material and a preparation method thereof.

Background

Graphene (Graphene) was discovered in 2004 and has been of interest since the day they were discovered. Although countless enthusiasm is caused, the graphene is still a key focus of researchers in many fields, the graphene is a new material with a two-dimensional honeycomb lattice structure formed by close packing of single-layer carbon atoms, the excellent mechanical property, electrical property and thermal property of the graphene are discovered sequentially due to the unique crystal structure characteristics of the graphene, and the graphene is expected to show wide application prospects in the research fields of microelectronics, functional materials, energy batteries and the like. The preparation of graphene in large area and high yield is a prerequisite for its wide application.

To date, the main methods for preparing graphene are: chemical vapor deposition, micro-mechanical lift-off, carbon nanotube cutting, liquid phase ultrasonic lift-off, redox, etc. The chemical reduction method is used for reducing the oxidized functional groups in the graphene oxide by the reducing agent to prepare the graphene, has the advantages of simple process, low cost, high conversion rate, batch production and the like, and is widely applied. However, reducing agents commonly used in chemical reduction methods at present, such as hydrazine hydrate and derivatives thereof, hydrogen iodide, sodium borohydride and the like, are substances with high toxicity or dangerous substances, and reduction reactions reported at present are generally performed in an aqueous solution, and the saturated concentration of a reduced graphene oxide aqueous dispersion is too low and unstable due to the hydrophobic property of the reduced graphene oxide, so that aggregation or pi-pi stacking is easy to occur, and the preparation efficiency and performance of graphene are seriously affected. The liquid phase ultrasonic stripping method has the advantages of simple process, low cost, environmental protection and the like, and is an effective method for realizing large-scale production of graphene. The all-carbon composite material has excellent properties of light weight, high heat conductivity, high modulus, low thermal expansion, high temperature and high strength of the traditional carbon/carbon composite material and the like, becomes a hot spot of the current composite material research, and has wide application prospect in the fields of aerospace, electronic technology, nuclear industry and the like.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide an all-carbon heat-conducting composite material and a preparation method thereof.

The technical purpose of the invention is realized by the following technical scheme:

an all-carbon heat-conducting composite material and a preparation method thereof are carried out according to the following steps:

step 1, performing liquid phase stripping by using expanded graphite to obtain graphene;

in the step 1, 0.1-0.5 part by mass of expanded graphite is uniformly dispersed in 100-150 parts by volume of N-methylpyrrolidone and reacted for 5-10 hours at 140-160 ℃ to obtain a graphene dispersion liquid; carrying out ultrasonic centrifugation on the obtained graphene dispersion liquid, taking supernatant, carrying out suction filtration to remove the NMP solvent, washing, carrying out ultrasonic treatment again to obtain a graphene solution, and carrying out freeze drying to obtain graphene powder;

in the step 1, performing ultrasonic treatment on the obtained graphene dispersion liquid for 10-30 min, then centrifuging at 2000r/min for 10-15 min, taking supernatant, performing suction filtration to remove NMP solvent, washing with water, performing ultrasonic treatment again to obtain graphene solution, and performing freeze drying to obtain graphene powder.

In step 1, 1g of each part by mass and 1mL of each part by volume were used.

Step 2, vertically growing graphene on the surface of the graphene prepared in the step 1 by using a PECVD system;

in the step 2, putting the prepared graphene into a PECVD system device, vacuumizing the PECVD system device, heating the graphene to 500-700 ℃, introducing a carbon source gas, keeping the vacuum and heating state, turning on a plasma source to perform vertical growth of the graphene, naturally cooling to the room temperature of 20-25 ℃ to obtain a sample of the vertical graphene grown on the surface of the graphene, and introducing an inert protective gas as a protective gas all the time in the process;

in step 2, the carbon source gas is methane, ethane or ethanol, and the gas flow rate is 1000-1300 sccm.

In the step 2, the inert protective gas is nitrogen, helium or argon, and the gas flow is 800-1000 sccm.

In step 2, the time for carrying out the vertical growth of the graphene is 5-20 min, preferably 10-15 min, and the vacuum is kept at 150-200 Pa.

And 3, mixing and stirring the sample of the graphene with the surface vertical to the surface of the graphene obtained in the step 2 and the mesophase pitch, pressurizing and melting, and cooling to obtain the all-carbon heat-conducting composite material.

In step 3, the mass ratio of the mesophase pitch to the sample of the graphene with the surface growth vertical graphene obtained in step 2 is (5-12): 1, preferably (8-12): 1, mixing and stirring the two materials, putting the mixture into a die, and performing pressure melting, wherein the hot pressing pressure is 1-5 MPa, the hot pressing temperature is 800-1000 ℃, and the hot pressing time is 10-15 min.

In the step 3, mesophase pitch is selected as a powder material, and the sample of the graphene with the surface growing vertical graphene obtained in the step 2 is ground into powder.

In the technical scheme of the invention, firstly, expanded graphite is used for liquid phase stripping to obtain graphene, then a PECVD system is used for vertically growing graphene on the surface of the prepared graphene (specifically, the references Bo Z, Yang Y, Chen J, et al, plasma-enhanced chemical vapor deposition synthesis of vertical oriented graphene nanosheets [ J ]. nanoscales, 2013,5(12): 5180-.

Drawings

Fig. 1 is a schematic flow and a schematic microstructure (heat conduction direction) of the present invention for preparing an all-carbon composite material.

Fig. 2 is a scanning electron microscope picture of the vertically grown graphene prepared by the present invention.

Detailed Description

The technical solution of the present invention is further described with reference to the following specific examples. The properties of the purchased mesophase pitch are as follows: content of black particle mesophase: 100%, softening point: 250 ℃ C., 300 ℃ C., quinoline insoluble: less than 5%, xylene insolubles: greater than 95%; specific references Bo Z, Yang Y, Chen J, et al, plasma-enhanced chemical vapor deposition synthesis of vertically oriented graphene nanosheets [ J ]. nanoscales, 2013,5(12): 5180-.