阅读说明：本技术 一种石墨烯掺杂c/c复合材料及其制备方法 (Graphene-doped C/C composite material and preparation method thereof ) 是由 陈奇志 李擎 喻林萍 万维华 沈玮俊 贺跃辉 方皓 王绍立 史磊 黄盛武 于 2019-12-03 设计创作，主要内容包括：本发明公开了一种石墨烯掺杂C/C复合材料的制备方法,包括如下步骤：S1)石墨/碳纤维/酚醛树脂热压坯的制备：将掺杂有石墨烯的石墨烘干除湿后与酚醛树脂充分混合,再与脱胶分散的碳纤维混合,热压成型；S2)碳/碳复合材料预制体的形成：将石墨/碳纤维/酚醛树脂热压坯在氩气氛保护下的高温碳化炉中梯度升温完成碳化过程；S3)采用化学气相渗透工艺,通过高温梯度沉积得碳/碳复合材料：以气态烃类为前驱气体,将碳/碳复合材料预制体的表面暴露于高温热分解的碳氢化合物气氛中,逐渐完成热解碳的沉积过程。本发明工艺过程简单,工艺参数易控,所得材料导电导热性能良好,强度高,可作为用于湿法冶金阴极的石墨烯掺杂C/C复合材料。(The invention discloses a preparation method of a graphene-doped C/C composite material, which comprises the following steps: s1) preparation of graphite/carbon fiber/phenolic resin hot pressed compact: drying and dehumidifying graphite doped with graphene, fully mixing the graphite with phenolic resin, mixing the mixture with degummed and dispersed carbon fibers, and performing hot press molding; s2) formation of carbon/carbon composite preform: carrying out gradient temperature rise on the graphite/carbon fiber/phenolic resin hot pressed compact in a high-temperature carbonization furnace under the protection of argon atmosphere to finish the carbonization process; s3) adopting a chemical vapor infiltration process, and obtaining the carbon/carbon composite material through high-temperature gradient deposition: and exposing the surface of the carbon/carbon composite material preform to a hydrocarbon atmosphere subjected to high-temperature thermal decomposition by taking gaseous hydrocarbons as precursor gas, and gradually finishing the deposition process of pyrolytic carbon. The method has the advantages of simple process, easily-controlled process parameters, good electric and heat conducting performance of the obtained material and high strength, and can be used as a graphene-doped C/C composite material for a hydrometallurgy cathode.)

1. A preparation method of a graphene-doped C/C composite material is characterized by comprising the following steps:

s1) preparation of graphite/carbon fiber/phenolic resin hot pressed compact: drying and dehumidifying graphite doped with graphene, fully mixing the graphite with phenolic resin, mixing the mixture with degummed and dispersed carbon fibers, and performing hot press molding;

s2) formation of carbon/carbon composite preform: the graphite/carbon fiber/phenolic resin hot pressed compact is subjected to gradient temperature rise in a high-temperature carbonization furnace under the protection of argon to complete the carbonization process;

s3) adopting a chemical vapor infiltration process, and obtaining the carbon/carbon composite material through high-temperature gradient deposition: and exposing the surface of the carbon/carbon composite material preform to a hydrocarbon atmosphere subjected to high-temperature thermal decomposition by taking gaseous hydrocarbons as precursor gas, and gradually finishing the deposition process of pyrolytic carbon.

2. The method for preparing the graphene-doped C/C composite material according to claim 1, wherein the content of Fe impurities in the graphite of the step S1 is less than 100ppm, and the median diameter is less than 10 μm; the length of the carbon fiber is 2-10 mu m; the mass percentage of the graphene doped in the graphite is 2.0-8.0%, and the balance is graphite; the mass percentage of free phenol in the phenolic resin is less than 10%.

3. The preparation method of the graphene-doped C/C composite material according to claim 1, wherein the hot-pressed compact of the step S1 comprises the following components in percentage by mass: the content of graphite powder is 30-60%; the carbon fiber content is 10-30%; the content of the phenolic resin is 20-40%.

4. The method for preparing the graphene-doped C/C composite material according to claim 1, wherein the control pressure range during the hot press molding in the step S1 is 30-100 MPa.

5. The method for preparing the graphene-doped C/C composite material according to claim 1, wherein the step S2 includes: preserving the heat of the hot pressed blank at 400 ℃ for 2-4 hours, preserving the heat at 400-600 ℃ for 4-8 hours, preserving the heat at 600-950 ℃ for 10-16 hours, and controlling the temperature rise speed to be 5 ℃/min; the initial density of the hot pressed compact is 0.2-0.9 g/cm³。

6. The method of preparing the graphene-doped C/C composite material according to claim 1, wherein the deposition source gas is methane, natural gas, a methane-hydrogen gas mixture or propane during the chemical vapor infiltration process in the step S3, and the flow rate of the deposition source gas is 0.20～0.8g/(h·mm²)。

7. The method for preparing the graphene-doped C/C composite material according to claim 1, wherein in the step S3, the deposition temperature ranges from 900 ℃ to 1050 ℃, and the furnace pressure ranges from 0.1 kPa to 5 kPa.

8. The preparation method of the graphene-doped C/C composite material according to claim 7, wherein in the step S3, the temperature rise speed is controlled to be 3-8 ℃/min, and the total high-temperature residence time is 20-42 hours.

9. A graphene-doped C/C composite material for a hydrometallurgical cathode, which is characterized by being prepared by the preparation method of any one of claims 1-8.

10. The graphene-doped C/C composite material for the hydrometallurgical cathode of claim 9, wherein the density of the C/C composite material is 1.3-1.5 g/cm³A resistivity of 11.8 to 15.0 [ mu ] omega.m and an impact toughness of 1.8 to 1.95J/cm²And the bending strength is 75-88 MPa.

Technical Field

The invention relates to a C/C composite material and a preparation method thereof, in particular to a graphene-doped C/C composite material and a preparation method thereof.

Background

The carbon/carbon (C/C) composite material integrates the excellent mechanical property of the fiber reinforced composite material and the excellent high-temperature property of the carbon material, and has a series of excellent properties such as high specific strength, specific modulus, good toughness, excellent strength retention rate at high temperature, creep resistance, thermal shock resistance and the like. The properties of carbon/carbon composites depend on the reinforcing carbon fibers, the matrix carbon, and the interface between the fibers and the matrix, with the density and structure of the matrix carbon being the most important factors affecting the mechanical properties. The pyrolytic carbon matrix is obtained by adopting a Chemical Vapor Infiltration (CVI) process and taking gaseous hydrocarbons as precursor gas through extremely complicated pyrolytic and deposition reaction processes.

At present, research and development of C/C composite materials are mainly focused on the high-technology fields of aerospace, aviation and the like, and are less concerned with research of civil high-performance and low-cost C/C composite materials. The overall research is still in the pursuit of the macroscopic properties of the material, the basic research on the organization structure, the property controllability, the adjustability and the like of the material is quite weak, and the requirement of national economic development on the high-performance C/C composite material is difficult to meet.

For example, hydrometallurgical electrolysis generally adopts copper as a cathode, the copper can be made into a large-size electrode, and the characteristic of high single-bath yield is achieved, but due to different use conditions, the quality defect that copper is mixed in an electrolytic finished product exists. Therefore, a substitute material for copper cathode is needed to further improve the hydrometallurgy technology and greatly improve the product quality.

Disclosure of Invention

The technical problem to be solved by the invention is to provide the graphene-doped C/C composite material and the preparation method thereof, the process is simple, the process parameters are easy to control, and the obtained material has good electric and heat conductivity and high strength; can be widely applied to the technical fields of hydrometallurgy electrolysis, catalytic carriers and the like.

The technical scheme adopted by the invention for solving the technical problems is to provide a graphene-doped C/C composite material and a preparation method thereof, and the preparation method comprises the following steps: s1) preparation of graphite/carbon fiber/phenolic resin hot pressed compact: drying and dehumidifying graphite doped with graphene, fully mixing the graphite with phenolic resin, mixing the mixture with degummed and dispersed carbon fibers, and performing hot press molding; s2) formation of carbon/carbon composite preform: the graphite/carbon fiber/phenolic resin hot pressed compact is subjected to gradient temperature rise in a high-temperature carbonization furnace under the protection of argon to complete the carbonization process; s3) adopting a chemical vapor infiltration process, and obtaining the carbon/carbon composite material through high-temperature gradient deposition: and exposing the surface of the carbon/carbon composite material preform to a hydrocarbon atmosphere subjected to high-temperature thermal decomposition by taking gaseous hydrocarbons as precursor gas, and gradually finishing the deposition process of pyrolytic carbon.

Further, the content of Fe impurities in the graphite in the step S1 is less than 100ppm, and the median diameter is less than 10 μm; the length of the carbon fiber is 2-10 mu m; the mass percentage of the graphene doped in the graphite is 2.0-8.0%, and the balance is graphite; the mass percentage of free phenol in the phenolic resin is less than 10%.

Further, the hot-pressed compact of step S1 includes the following components in percentage by mass: the content of graphite powder is 30-60%; the carbon fiber content is 10-30%; the content of the phenolic resin is 20-40%.

Further, the control pressure range during the hot press molding in the step S1 is 30 to 100 MPa.

Further, the step S2 includes: preserving the heat of the hot pressed blank at 400 ℃ for 2-4 hours, preserving the heat at 400-600 ℃ for 4-8 hours, preserving the heat at 600-950 ℃ for 10-16 hours, and controlling the temperature rise speed to be 5 ℃/min; the initial density of the hot pressed compact is 0.2-0.9 g/cm³。

Further, in the chemical vapor infiltration process in the step S3, the deposition source gas is methane, natural gas, a methane-hydrogen mixture, or propane, and the flow rate of the deposition source gas is 0.20 to 0.8g/(h · mm)²)。

Further, in the step S3, the deposition temperature ranges from 900 ℃ to 1050 ℃, and the furnace pressure ranges from 0.1 kPa to 5 kPa.

Further, in the step S3, the temperature rise speed is controlled to be 3-8 ℃/min, and the total high-temperature residence time is 20-42 hours.

The technical scheme adopted by the invention for solving the technical problems is to provide the graphene doped C/C composite material for the hydrometallurgy cathode, and the graphene doped C/C composite material is prepared by the preparation method.

Further, the density of the C/C composite material is 1.3-1.5 g/cm³A resistivity of 11.8 to 15.0 [ mu ] omega.m and an impact toughness of 1.8 to 1.95J/cm²And the bending strength is 75-88 MPa.

Compared with the prior art, the invention has the following beneficial effects: the invention provides a graphene doped C/C composite material and a preparation method thereof.A hot press molding method is adopted to obtain a graphite (graphene)/carbon fiber/phenolic resin green body, a carbon/carbon composite material prefabricated body with a small amount of pore structures is formed after high-temperature carbonization, a Chemical Vapor Infiltration (CVI) method is adopted, gaseous hydrocarbons are taken as precursor gas, hydrocarbon gas molecules are dissociated on the hot deposition surface, and the pores are filled by pyrolytic carbon generated by gas-solid surface multiphase reaction, so that the prefabricated body is densified, and a C/C composite material cathode with good conductivity and high strength is obtained. Compared with the copper cathode which is used in large quantity at present, the C/C composite material cathode does not introduce metal impurities in the electrolytic process, the electrode polarization process is stable, and the quality of the product prepared by wet metallurgy is greatly improved. The C/C composite material has the advantages of easy control of process parameters, low cost and suitability for large-scale production.

Drawings

FIG. 1 is a schematic view of a surface micro-topography of a graphene doped C/C composite material in an embodiment of the invention;

FIG. 2 is a schematic diagram of a cross section of a graphene-doped C/C composite material showing the thickness of a CVI deposition layer according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a product shape of a graphene-doped C/C composite material obtained by strongly polarizing, electrolytically peeling a CVI surface layer in an embodiment of the invention;

FIG. 4 is an X-ray diffraction analysis chart of a matrix of a graphene-doped C/C composite material according to an embodiment of the present invention;

FIG. 5 is a Raman analysis diagram of a product obtained by strongly polarizing, electrolytically peeling and separating a CVI surface layer from a graphene-doped C/C composite material in an embodiment of the invention.

Detailed Description

The invention is further described below with reference to the figures and examples.

The preparation method of the graphene doped C/C composite material provided by the invention comprises the following steps:

s1) preparation of graphite/carbon fiber/phenolic resin hot pressed compact: drying and dehumidifying graphite doped with graphene, fully mixing the graphite with phenolic resin, mixing the mixture with degummed and dispersed carbon fibers, and performing hot press molding; the hot pressed blank comprises the following components in percentage by weight: the graphite powder content is 30-60%, the graphite content is too low, and the material resistance is too high; the carbon fiber content is 10-30% to improve the strength of the material; in order to realize smooth compression molding, the content of the phenolic resin is 20-40%;

s2) formation of carbon/carbon composite preform: the graphite/carbon fiber/phenolic resin hot pressed compact is subjected to gradient temperature rise in a high-temperature carbonization furnace under the protection of argon to complete the carbonization process;

s3) adopting a chemical vapor infiltration process, and obtaining the carbon/carbon composite material through high-temperature gradient deposition: and exposing the surface of the carbon/carbon composite material preform to a hydrocarbon atmosphere subjected to high-temperature thermal decomposition by taking gaseous hydrocarbons as precursor gas, and gradually finishing the deposition process of pyrolytic carbon.

The pyrolytic reaction process of pyrolytic carbon is accompanied by the formation, growth and dehydrogenation of a series of cyclic compounds, hydrocarbon gas molecules are dissociated on a hot deposition surface to form free radicals or relatively complex molecules, products obtained by the reaction are continuously decomposed on the surface of a substrate and return to a gas space to carry out gaseous polymerization reaction, the reactions are repeated, finally some hydrocarbons reach the surface of the substrate to simultaneously generate aromatic molecules, aliphatic molecules or free radicals, the conversion reaction is carried out in a high-temperature region near the deposition surface to generate various high-polymerization aromatic compounds, and finally the formed pyrolytic carbon is of a disordered-layer graphite structure. On one hand, the pyrolytic carbon deposition layer fills pores to densify the preform, and on the other hand, the surface of the substrate with high electric and thermal conductivity is obtained, so that the product has excellent electrochemical performance. The continuous preparation technology for hydrometallurgy electrolysis cathode application is realized by combining high-temperature carbonization and a chemical vapor reaction infiltration method, and the density of the obtained C/C composite material is more than 1.3g/cm³The resistivity is lower than 15.0 mu omega-m, and the impact toughness is more than 1.8J/cm²The bending strength is more than 75 MPa.

One specific example is given below:

weighing 500g of graphite after drying and dehumidifying, fully mixing with 35g of high-purity reduced graphene, adding 300g of phenolic resin, uniformly mixing, fully mixing with 150g of degummed and dispersed carbon fiber, carrying out hot press molding under 80MPa, and carrying out gradient temperature rise in a high-temperature carbonization furnace under the protection of argon atmosphere on graphite (graphene)/carbon fiber/phenolic resin hot pressed blank to 950 ℃ to complete the full carbonization process, wherein the temperature is kept at 500 ℃ for 6 hours, the temperature is kept at 800 ℃ for 12 hours, and the temperature rise rate is 5 ℃/min, so as to obtain a carbon/carbon composite material preform; methane is taken as precursor gas, and the flow rate is controlled to be 0.65 g/(h.mm)²) Fully exposing the surface of the C/C composite material prefabricated body to the hydrocarbon gas atmosphere decomposed by high-temperature heat, and gradually completing pyrolysisThe carbon deposition process and the matrix carbon graphitization process are kept at 600 ℃ for 8 hours, 850 ℃ for 6 hours and 1050 ℃ for 20 hours, and the furnace pressure is kept within 2.0 kPa. The density of the obtained C/C composite material is 1.32g/cm³Resistivity of 14.0. omega. m, and impact toughness of 1.9J/cm²And the bending strength is 80 MPa. The surface micro-topography is shown in figure 1, and a compact CVI deposition layer mainly containing pyrolytic carbon is formed; the CVI deposition layer was 22 μm thick as shown in fig. 2. The product obtained by carrying out strong polarization electrolytic stripping on the CVI surface layer by using the graphene-doped C/C composite material comprises a multi-layer graphene structure, and is shown in figure 3; x-ray diffraction analysis shows a good graphite crystal structure of the material matrix, as shown in FIG. 4, the abscissa is 2 θ angle (Two Theta, unit: degree) and the ordinate is diffraction intensity (unit: a.u.); raman results show the characteristic vibration peak position D-band (1350 cm) of CVI (chemical vapor deposition) layer graphene^-1) And G-band (1580 cm)^-1) And the D-band intensity is higher than the G-band, as shown in fig. 5, the abscissa in fig. 5 is the Raman shift (unit: cm^-1) The ordinate is the raman intensity (unit: a.u.); the CVI deposition layer is shown to generate graphene with a certain composition through the control of temperature and ventilation besides pyrolytic carbon components.

Although the present invention has been described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.