A high-strength, high-thermal-conductivity graphite-ceramic composite material and its preparation method

Abstract

This invention discloses a method for preparing a high-strength, high-thermal-conductivity graphite ceramic composite material. The graphite ceramic composite material is composed of graphite powder, a silicon carbide reinforcing network, and glassy carbon. The silicon carbide reinforcing network consists of a dendritic silicon carbide network and a regularized silicon carbide network. The preparation process of the high-strength, high-thermal-conductivity graphite ceramic composite material includes powder mixing, layer-unit micro-hot pressing, interlayer degassing network construction, repeated processes, pressure-holding curing, rapid carbonization, multiple impregnation strengthening, and high-temperature sintering. The method for preparing the high-strength, high-thermal-conductivity graphite ceramic composite material provided by this invention has advantages such as low energy consumption and low cost. It belongs to pressureless sintering technology and is suitable for the preparation of large-size graphite ceramic composite materials. The obtained graphite ceramic composite material possesses high strength, high thermal conductivity, oxidation resistance, and thermal shock resistance, and has broad application prospects in high-temperature casting, civilian and military equipment, and other fields.

Description

Technical Field

[0001] This invention provides a high-strength, high-thermal-conductivity graphite ceramic composite material and its preparation method, belonging to the field of inorganic non-metallic material forming technology, and relating to the development and application of a high-strength, high-thermal-conductivity graphite ceramic composite material. Technical Background

[0002] Carbon-graphite materials are widely used in aerospace, casting, energy, and chemical industries due to their excellent properties such as lightweight, high strength, high thermal conductivity, high temperature resistance, and thermal shock resistance. However, in actual production processes, stress release and pyrolysis of binders can lead to structural defects such as porosity, cracks, and disordered layering. These defects significantly affect the mechanical properties and oxidation resistance of the materials. Research shows that combining ceramics as a reinforcing phase with a graphite matrix can reduce microstructural defects within the graphite matrix, thereby improving its mechanical properties and oxidation resistance. Currently, ceramic reinforcing phases in graphite matrices are mainly distributed in two ways: dispersed distribution and continuous distribution.

[0003] Han Yongjun et al. prepared SiC-reinforced graphite composites using natural flake graphite powder and SiC powder as raw materials. After pre-pressing, the composite material underwent liquid-phase hot pressing and sintering. When the SiC content was 20 vol%, the in-plane thermal conductivity was 219 W / m·K, significantly higher than that of typical polycrystalline graphite. Its flexural strength reached 105 MPa, 1.75 times that of commercially available high-strength pure graphite samples. Zhang Xiaoyu et al. prepared AlN-reinforced highly oriented graphite composites by ball milling and uniformly mixing natural flake graphite powder and aluminum nitride (AlN), followed by SPS sintering. These composites exhibited high thermal conductivity along the graphite flake direction, reaching 364 W / m, but their flexural strength was relatively low, at only 73 MPa. Furthermore, Zhang Xiaoyu et al. successfully prepared uniform and continuous WC-reinforced highly oriented graphite composites by coating the surface of natural flake graphite powder with a uniformly controllable WC coating using a molten salt method, followed by SPS sintering at 50 MPa. When the WC reinforcing phase content was 26 vol%, the composite material obtained exhibited the best overall performance, with a density of 94.6%, a flexural strength of 95 MPa, and a thermal conductivity of 381 W / m·K. Yang Jinhua et al. selected four graphite preforms with different pore structures for melt-infiltrating reaction. Their research showed that the melt-infiltrated composite material consisted of three phases: graphite, silicon, and silicon carbide. Furthermore, the distribution of silicon and silicon carbide was closely related to the pore structure of the graphite. The strength of the melt-infiltrated material was 1.7–6.2 times that of the original graphite sample.

[0004] The current methods for preparing graphite ceramic composites have the following shortcomings: (1) Graphite ceramic composites mainly adopt hot pressing sintering, ion sintering (SPS) and melt infiltration, which have high requirements for process equipment and make it difficult to prepare large-size graphite ceramic composites; (2) It is difficult to control the spatial distribution of ceramic reinforcing phase, resulting in limited improvement of the overall performance of composite materials; (3) The production and preparation cycle is long, energy consumption is high and cost is high.

[0005] In summary, a new preparation process is urgently needed to solve the problem of preparing large-size graphite-ceramic composite materials, while achieving controllable distribution of the ceramic phase, thereby eliminating and reducing defects such as internal cracks and pores in graphite and improving its performance. Summary of the Invention

[0006] In view of the shortcomings of the current graphite ceramic composite process technology, this invention provides a high-strength and high-thermal-conductivity graphite ceramic composite material and its preparation method. The invention idea and technical principle are as follows: (1) Using the principle of micro-thermal pressing additive manufacturing technology, the mixed powder is shaped. Under the combined action of temperature field, shear force of powder spreading roller and electromagnetic force, the natural flake graphite powder is deflected and oriented, so that the graphite ceramic composite has a high thermal conductivity in a certain direction; (2) The interlayer exhaust network structure is realized in the process of forming the graphite ceramic composite green body. The exhaust network channel is formed before the binder is pyrolyzed in large quantities. (2) By repeatedly impregnating with silica sol and melting silica to strengthen and fill the exhaust network channels, and fill the pores left by the pyrolysis of phenolic resin, when the silica completely fills the exhaust network in the early stage, it will also generate a regular silica network according to the designed network structure. In this process, some silica sol solution and the solution generated after melting silica will penetrate along the thickness direction through the exhaust channel, thereby forming a dendritic silica network and improving the strength of graphite ceramic composite material.

[0007] A high-strength, high-thermal-conductivity graphite-ceramic composite material and its preparation method, comprising the following specific steps:

[0008] (1) Preparation of mixed powder: graphite powder, silicon powder and thermosetting phenolic resin powder are mixed by ball milling;

[0009] (2) Layer unit micro-thermo-pressing: After the mixed powder is spread out, the heated powder is rapidly pressed into a selected area using an electromagnetic press head. The density of the graphite ceramic composite material is controlled to be 1.8-1.9 g / cm³ by controlling the downward distance of the press head (controlled according to the thickness of the unit layer, 0.5~5 mm). 3 By adjusting the impact speed of the pressure head to 100-150 times / min, and stacking them layer by layer, a graphite ceramic composite material layer unit is obtained.

[0010] (3) Interlayer exhaust network structure: an exhaust network is printed on the layer unit by a high-voltage electrostatic melting 3D printer, and after curing and carbonization, a graphite ceramic composite material preform is obtained;

[0011] (4) Impregnation with phenolic resin solution: The graphite ceramic composite preform is impregnated in phenolic resin solution, dried and then rapidly carbonized to obtain a graphite ceramic composite preform impregnated with phenolic resin.

[0012] (5) Impregnation with silica sol solution: The preform from step (4) is impregnated in silica sol solution, dried and then rapidly carbonized to obtain a graphite ceramic composite preform impregnated with silica sol.

[0013] (6) Melt infiltration: After mixing the graphite ceramic composite material preform impregnated with silica sol with silica powder, high-temperature melt infiltration is carried out to obtain a high-strength and high-thermal-conductivity graphite ceramic composite material.

[0014] The mixed powder in step (1) includes graphite powder of 150-700 mesh with a carbon content greater than 98% and a mass fraction of 40-70 wt.%; high-purity silicon powder of 200-900 mesh with a chemical purity of 99% and a mass fraction of 20-40 wt.%; and thermosetting phenolic resin powder of 150-800 mesh with a mass fraction of 20-35 wt.%. The mixed powder is placed in a dry ball mill and mixed for 4-10 hours until it is homogeneous.

[0015] The micro-hot pressing process parameters for the layer unit in step (2) are: forming pressure 5~100 MPa, holding time 10~60 min, layer unit thickness 0.5~5 mm, and heating temperature 80~140℃.

[0016] The interlayer venting network construction in step (3) refers to printing the venting network on the layer unit using a high-voltage electrostatic melting 3D printer. The structure of the venting network is a sun ring structure, a spider web structure, or a grid structure, etc. The material is polylactic acid PLA or poly(ε-caprolactone) PCL, and its diameter is 0.01~10 μm. The process parameters of the high-voltage electrostatic melting 3D printer are: receiving platform temperature 5℃~20℃, printing speed 10~60 mm / s, high voltage 1~10kV can be applied, nozzle temperature 20℃~200℃, and heating rate ≤5 min.

[0017] After constructing the exhaust network on the layer unit in step (3), the layer unit micro hot pressing molding is repeated to prepare the layer unit and the exhaust network alternately to obtain the graphite ceramic composite material blank.

[0018] The curing temperature is 140℃~220℃, and the pressure is 5~80 MPa;

[0019] The rapid carbonization process is as follows: evacuate to 100 Pa or below, heat to 300°C at a rate of 120-180°C / h; heat to 700°C at a rate of 60-120°C / h, and fill with 99% pure argon or nitrogen gas at 300-350°C, and hold at 380-400°C for 0.5-1 h; finally, heat to 800°C at 130-160°C / h, hold for 1-3 h, cool to room temperature with the furnace, and remove to obtain a graphite ceramic composite preform.

[0020] In step (4), the phenolic resin solution is impregnated, with a concentration of 20–40 wt.%. The impregnation process parameters are as follows: first, the vacuum degree is reduced to below 100 Pa, and then the phenolic resin solution is impregnated into the graphite ceramic composite preform under a pressure of 0.1–0.5 MPa. Subsequently, it is dried in a hot air drying oven at a temperature below 100°C to obtain the graphite ceramic composite preform. The rapid carbonization process is the same as in step (3).

[0021] In the process of impregnating the silica sol solution in step (5): first, the vacuum degree is evacuated to 100 Pa or below, and the silica sol solution is impregnated into the graphite ceramic composite preform under a pressure of 0.1 to 0.5 MPa, and then dried in a hot air drying oven at a temperature below 100°C; the rapid carbonization process is the same as in step (3).

[0022] After repeating the impregnation process in steps (4) and (5), rapid carbonization is carried out. This process is repeated 2 to 4 times to obtain a graphite ceramic composite preform.

[0023] In step (5), the molten silicon infiltration involves placing high-purity silicon powder (200-900 mesh, 99% chemical purity) into a graphite crucible, then placing the graphite ceramic composite material preform into the crucible, evacuating to below 100 Pa, first heating to 300°C at 120-180°C / h, then heating to 700°C at 60-120°C / h, and filling with 99% pure argon or nitrogen gas at 300-350°C; finally heating to 1500-1600°C at 100-160°C / h, holding for 1-3 hours, and then removing the material to obtain a high-strength, high-thermal-conductivity graphite ceramic composite material.

[0024] The above-mentioned technical method has the following advantages:

[0025] 1. By incorporating a low-melting-point (PLA melting point is 105℃, PCL melting point is 62℃) exhaust network to construct an "exhaust channel", the gas can be rapidly released from the graphite matrix during the carbonization process, effectively avoiding crack defects that occur in large-size graphite ceramic composite materials during rapid carbonization, reducing production energy consumption, and significantly increasing the carbonization rate.

[0026] 2. The low-melting-point exhaust network is made of polylactic acid (PLA) or poly(ε-caprolactone) (PCL). This material has the advantages of low melting point, low carbon residue and low cost, and can ensure complete decomposition during the large-scale pyrolysis of phenolic resin to form an exhaust channel.

[0027] 3. This method involves combining graphite and silicon carbide ceramics, and filling the exhaust network channels through multiple impregnations with silica sol and molten silica infiltration, as well as filling the pores left by the pyrolysis of phenolic resin. When the silicon carbide completely fills the previously constructed exhaust network, a regular silicon carbide network will be generated according to the designed network structure. During this process, some silica sol solution and the solution generated after molten silica infiltration will permeate along the thickness direction through the exhaust channels, thereby forming a dendritic silicon carbide network and improving the strength of the graphite ceramic composite material. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the silicon carbide reinforced network structure inside the composite material.

[0029] Figure 2 This is a process flow diagram for the preparation of high-strength, high-thermal-conductivity graphite ceramic composite materials.

[0030] Figure 3 This is a schematic diagram of the designed exhaust network structure.

[0031] Figure 4 This is a comparison image of carbonized samples with and without an exhaust network. Detailed Implementation

[0032] Example 1

[0033] A high-strength, high-thermal-conductivity graphite ceramic composite material and its preparation method are disclosed. The graphite ceramic composite material is composed of natural flake graphite powder, high-purity silicon powder, and thermosetting phenolic resin powder, wherein the mass fraction of natural flake graphite powder is 40 wt.% (200 mesh), the mass fraction of high-purity silicon powder is 40 wt.% (200 mesh), and the mass fraction of thermosetting phenolic resin powder is 20 wt.% (500 mesh).

[0034] use Figure 2 The process flow diagram is described above. The specific preparation steps are as follows: (1) Preparation of graphite ceramic composite green body

[0035] The prepared mixed powder was spread out and layer units were fabricated using micro-hot pressing. The micro-hot pressing process parameters were: forming pressure 30 MPa, unit layer thickness 4 mm (the compression distance was controlled to be 4 mm based on the unit layer thickness of 4 mm), heating temperature 120℃, and indenter impact speed 100 times / min. A low-melting-point exhaust network was then directly printed on the layer units using a high-voltage electrostatic melting 3D printer. The exhaust network has a solar ring structure. Figure 3 In the middle (1), the diameter of the solar ring skeleton is 1μm, the material is poly(ε-caprolactone) PCL, and the process parameters of the high-voltage electrostatic melting 3D printer are: receiving platform temperature 5℃, printing speed 10mm / s, applied high voltage 4kV, nozzle temperature 150℃, heating rate ≤5 min. After constructing the exhaust network on the layer unit, the layer unit micro-thermal pressing and interlayer exhaust network construction steps are continued. The layer unit and exhaust network are prepared alternately 3 times to complete the graphite ceramic composite material blank. Then, it is cured under pressure for a period of time, according to the curing temperature of 110℃, the pressure of 30MPa, and the heat and pressure holding for 20 min.

[0036] (2) Post-treatment of graphite ceramic composite preform

[0037] The graphite-ceramic composite was placed in a carbonization furnace. Based on the dissolution and decomposition temperatures of the exhaust network, a suitable carbonization process was developed as follows: The vacuum was evacuated to 80 Pa, and the temperature was increased to 300℃ at a rate of 120℃ / h; then increased to 700℃ at a rate of 80℃ / h, and 99% pure nitrogen was introduced at 350℃, and the temperature was held at 380℃ for 0.5 h; finally, the temperature was increased to 800℃ at a rate of 130℃ / h, held for 1 h, and then cooled to room temperature in the furnace. The resulting graphite-ceramic composite preform was then obtained. Next, an impregnation treatment was performed. The detailed process was as follows: first, the preform was impregnated with a phenolic resin solution for rapid carbonization; second, it was impregnated with a silica sol solution for rapid carbonization (the impregnation with phenolic resin and silica sol solutions was repeated twice) to obtain the graphite-ceramic composite preform. The impregnation process parameters are as follows: vacuum level is increased to 80 Pa, and the impregnation solution is impregnated into the carbonized graphite ceramic composite preform under a pressure of 0.5 MPa, followed by drying in a 100℃ hot air drying oven. The obtained preform undergoes melt-infiltration treatment: 500-mesh high-purity silicon powder with a chemical purity of 99% is placed in a graphite crucible, and then the graphite ceramic composite preform is also placed in the crucible. Melt-infiltration of the graphite ceramic composite preform is performed in a carbonization furnace at 1500℃. The detailed process is as follows: vacuum level is increased to below 100 Pa, the temperature is first increased to 300℃ at 140℃ / h, then increased to 700℃ at 90℃ / h, and 99% pure argon is introduced at 350℃; finally, the temperature is increased to 1500℃ at 130℃ / h, held for 1 h, and then removed to obtain a high-strength, high-thermal-conductivity graphite ceramic composite material. A schematic diagram of the silicon carbide reinforced network structure inside the composite material is shown below. Figure 1 As shown in the figure. Experiments revealed that the graphite-ceramic composite material prepared by this process has dimensions of 400 × 300 × 240 mm and a density of 1.81 g / cm³. 3 It has a thermal conductivity of 242.58 W / m∙K, a compressive strength of 157.16 MPa, and a smooth surface without bulges or cracks (e.g., Figure 4 (As shown in B).

[0038] The sample without an exhaust network, after undergoing the same after-treatment process, developed bulges and irregular cracks. Figure 4 As shown in Figure A), the thermal conductivity is 180 W / m∙K and the compressive strength is 60.52 MPa.

[0039] Example 2

[0040] A high-strength, high-thermal-conductivity graphite ceramic composite material and its preparation method are disclosed. The graphite ceramic composite material is composed of natural flake graphite powder, high-purity silicon powder, and thermosetting phenolic resin powder, wherein the mass fraction of natural flake graphite powder is 40 wt.% (200 mesh), the mass fraction of high-purity silicon powder is 40 wt.% (200 mesh), and the mass fraction of thermosetting phenolic resin powder is 20 wt.% (500 mesh).

[0041] The specific preparation steps are as follows: (1) Preparation of graphite ceramic composite green body

[0042] The prepared mixed powder was spread out and layer units were fabricated using micro-hot pressing. The micro-hot pressing process parameters were: forming pressure 30 MPa, unit layer thickness 2 mm (the compression distance was controlled to be 2 mm based on the unit layer thickness of 2 mm), heating temperature 120℃, and indenter impact speed 100 times / min. A low-melting-point exhaust network was then directly printed on the layer units using a high-voltage electrostatic melting 3D printer. The exhaust network had a spider web structure. Figure 3 In the middle (2), the diameter of the spider web skeleton is 2μm, the material is polylactic acid PLA, and the process parameters of the high-voltage electrostatic melting 3D printer are: receiving platform temperature 5℃, printing speed 10 mm / s, applied high voltage 4kV, nozzle temperature 150℃, heating rate ≤5 min. After constructing the exhaust network on the layer unit, the steps of layer unit micro-thermal pressing and interlayer exhaust network construction are continued. The layer unit and exhaust network are prepared alternately 3 times to complete the graphite ceramic composite material blank. Then, it is cured under pressure for a period of time, according to the curing temperature of 110℃, the pressure of 30 MPa, and the heat and pressure holding for 20 min.

[0043] (2) Post-treatment of graphite ceramic composite preform

[0044] The graphite-ceramic composite was placed in a carbonization furnace. Based on the dissolution and decomposition temperatures of the exhaust network, a suitable carbonization process was developed as follows: The vacuum was evacuated to 80 Pa, and the temperature was increased to 300℃ at a rate of 120℃ / h; then increased to 700℃ at a rate of 80℃ / h, and 99% pure nitrogen was introduced at 350℃, and the temperature was held at 380℃ for 0.5 h; finally, the temperature was increased to 800℃ at a rate of 130℃ / h, held for 1 h, and then cooled to room temperature in the furnace. The resulting graphite-ceramic composite preform was then obtained. Next, an impregnation treatment was performed. The detailed process was as follows: first, the preform was impregnated with a phenolic resin solution for rapid carbonization; second, it was impregnated with a silica sol solution for rapid carbonization (this process was repeated three times with the phenolic resin and silica sol solutions) to obtain the graphite-ceramic composite preform. The impregnation process parameters are as follows: vacuum level is increased to 80 Pa, and the impregnation solution is impregnated into the carbonized graphite ceramic composite preform under a pressure of 0.5 MPa, followed by drying in a 100℃ hot air drying oven. The obtained preform undergoes melt-infiltration treatment: 500-mesh high-purity silicon powder with a chemical purity of 99% is placed in a graphite crucible, and then the graphite ceramic composite preform is also placed in the crucible. Melt-infiltration of the graphite ceramic composite preform is performed in a carbonization furnace at 1500℃. The detailed process is as follows: vacuum level is increased to below 100 Pa, the temperature is first increased to 300℃ at 140℃ / h, then increased to 700℃ at 90℃ / h, and 99% pure argon is introduced at 350℃; finally, the temperature is increased to 1500℃ at 130℃ / h, held for 1 h, and then removed to obtain a high-strength, high-thermal-conductivity graphite ceramic composite material. A schematic diagram of the silicon carbide reinforced network structure inside the composite material is shown below. Figure 1 As shown.

[0045] Experiments showed that the graphite-ceramic composite material prepared by this process had dimensions of 400×300×240 mm and a density of 1.76 g / cm³. 3 It has a thermal conductivity of 220.15 W / m∙K, a compressive strength of 139.54 MPa, a smooth surface, and no bulges or cracks (the morphological structure diagram is similar to that of Example 1).

[0046] Example 3

[0047] The process is basically the same as in Example 1, except that the structure of the exhaust network in step (1) of preparing the graphite ceramic composite green body is changed to a grid-like structure. Figure 3 In the middle (3), the diameter of the grid-shaped skeleton is 2μm.

[0048] Experiments showed that the graphite-ceramic composite material prepared by this process had dimensions of 400×300×240 mm and a density of 1.79 g / cm³. 3It has a thermal conductivity of 215.43 W / m∙K, a compressive strength of 138.47 MPa, a smooth surface, and no bulges or cracks (the morphological structure diagram is similar to that of Example 1).

[0049] Example 4

[0050] The process is basically the same as in Example 1, except that the material of the exhaust network skeleton in step (1) of preparing the graphite ceramic composite green body is polylactic acid PLA and the diameter is changed to 2 μm.

[0051] Experiments showed that the graphite-ceramic composite material prepared by this process had dimensions of 400×300×240 mm and a density of 1.85 g / cm³. 3 It has a thermal conductivity of 241.72 W / m∙K, a compressive strength of 165.73 MPa, a smooth surface, and no bulges or cracks (the morphological structure diagram is similar to that of Example 1).

[0052] Example 5

[0053] The process is basically the same as in Example 1, except that the number of times the phenolic resin solution and silica sol solution are repeated in the post-treatment of the graphite ceramic composite green body in step (2) is changed to 3.

[0054] Experiments showed that the graphite-ceramic composite material prepared by this process had dimensions of 400×300×240 mm and a density of 1.84 g / cm³. 3 It has a thermal conductivity of 261.72 W / m∙K, a compressive strength of 174.23 MPa, a smooth surface, and no bulges or cracks (the morphological structure diagram is similar to that of Example 1).

[0055] Example 6

[0056] The process is basically the same as in Example 2, except that the number of times the phenolic resin solution and silica sol solution are repeated in the post-treatment of the graphite ceramic composite green body in step (2) is changed to 3.

[0057] Experiments showed that the graphite-ceramic composite material prepared by this process had dimensions of 400×300×240 mm and a density of 1.79 g / cm³. 3 It has a thermal conductivity of 221.56 W / m∙K, a compressive strength of 143.23 MPa, a smooth surface, and no bulges or cracks (the morphological structure diagram is similar to that of Example 1).

Claims

1. A method for preparing a high-strength, high-thermal-conductivity graphite-ceramic composite material, characterized in that, Includes the following steps: (1) Preparation of mixed powder: graphite powder, silicon powder and thermosetting phenolic resin powder are mixed by ball milling; (2) Layer unit micro hot pressing molding: After the mixed powder is spread out, the heated powder is rapidly pounded in the selected area using an electromagnetic pressure head. The density of the graphite ceramic composite material is controlled by controlling the descent distance of the pressure head. By adjusting the pounding speed of the pressure head to 100~150 times / min, layers are stacked to obtain the graphite ceramic composite material layer unit. (3) Interlayer exhaust network construction: an exhaust network is printed on the layer unit by a high-voltage electrostatic melting 3D printer. After curing and carbonization, a graphite ceramic composite material preform is obtained. The structure of the interlayer exhaust network is a sun ring structure, a spider web structure or a grid structure. The material is polylactic acid PLA or polyε-caprolactone PCL, and its diameter is 0.01~10 μm. (4) Impregnation with phenolic resin solution: The graphite ceramic composite preform is impregnated in phenolic resin solution, dried and then rapidly carbonized to obtain a graphite ceramic composite preform impregnated with phenolic resin. (5) Impregnation with silica sol solution: The preform from step (4) is impregnated in silica sol solution, dried and then rapidly carbonized to obtain a graphite ceramic composite preform impregnated with silica sol. (6) Melt infiltration: After mixing the graphite ceramic composite material preform impregnated with silica sol with silica powder, high-temperature melt infiltration is carried out to obtain a high-strength and high-thermal-conductivity graphite ceramic composite material.

2. The method for preparing the high-strength, high-thermal-conductivity graphite-ceramic composite material according to claim 1, characterized in that, In step (1), the mixed powder consists of graphite powder of 150-700 mesh with a carbon content greater than 98% and a mass fraction of 40-70 wt.%; silicon powder of 200-900 mesh with a chemical purity of 99% and a mass fraction of 20-40 wt.%; and thermosetting phenolic resin powder of 150-800 mesh with a mass fraction of 20-35 wt.%.

3. The method for preparing the high-strength, high-thermal-conductivity graphite-ceramic composite material according to claim 1, characterized in that, The micro-hot pressing process parameters for the layer unit in step (2) are: forming pressure 5~100 MPa, holding time 10~60 min, layer unit thickness 0.5~5 mm, and heating temperature 80~140℃.

4. The method for preparing the high-strength, high-thermal-conductivity graphite-ceramic composite material according to claim 1, characterized in that, The process parameters of the high-voltage electrostatic melting 3D printer in step (3) are: receiving platform temperature 5℃~20℃, printing speed 10~60 mm / s, high voltage 1~10kV can be applied, nozzle temperature 20℃~200℃, and heating rate ≤5 min.

5. The method for preparing the high-strength, high-thermal-conductivity graphite-ceramic composite material according to claim 1, characterized in that, After constructing the exhaust network on the layer unit in step (3), the layer unit micro hot pressing molding is repeated to prepare the layer unit and the exhaust network alternately to obtain the graphite ceramic composite material blank. The curing temperature is 140℃~220℃, and the pressure is 5~80 MPa; The rapid carbonization process is as follows: evacuate to 100 Pa or below, heat to 300°C at a rate of 120-180°C / h; heat to 700°C at a rate of 60-120°C / h, and fill with 99% pure argon or nitrogen gas at 300-350°C, and hold at 380-400°C for 0.5-1 h; finally, heat to 800°C at 130-160°C / h, hold for 1-3 h, cool to room temperature with the furnace, and remove to obtain a graphite ceramic composite preform.

6. The method for preparing the high-strength, high-thermal-conductivity graphite-ceramic composite material according to claim 1, characterized in that, In the impregnation process of the phenolic resin solution in step (4), the concentration of the phenolic resin solution is 20-40 wt.%, and the impregnation process parameters are as follows: first, the vacuum degree is evacuated to 100 Pa or below, and the phenolic resin solution is impregnated into the graphite ceramic composite preform under a pressure of 0.1-0.5 MPa, and then dried in a hot air drying oven at a temperature below 100°C; the rapid carbonization process is the same as in step (3).

7. The method for preparing the high-strength, high-thermal-conductivity graphite-ceramic composite material according to claim 1, characterized in that, In the process of impregnating the silica sol solution in step (5): first, the vacuum degree is evacuated to 100 Pa or below, and the silica sol solution is impregnated into the graphite ceramic composite preform under a pressure of 0.1 to 0.5 MPa, and then dried in a hot air drying oven at a temperature below 100°C; the rapid carbonization process is the same as in step (3).

8. The method for preparing the high-strength, high-thermal-conductivity graphite-ceramic composite material according to claim 1, characterized in that, After repeating the impregnation process in steps (4) and (5), rapid carbonization is carried out. This process is repeated 2 to 4 times to obtain a graphite ceramic composite preform.

9. The method for preparing the high-strength, high-thermal-conductivity graphite-ceramic composite material according to claim 1, characterized in that, In step (5), the molten silicon infiltration involves placing high-purity silicon powder (200-900 mesh, 99% chemical purity) into a graphite crucible, then placing the graphite ceramic composite material preform into the crucible, evacuating to below 100 Pa, first heating to 300°C at 120-180°C / h, then heating to 700°C at 60-120°C / h, and filling with 99% pure argon or nitrogen gas at 300-350°C; finally heating to 1500-1600°C at 100-160°C / h, holding for 1-3 hours, and then removing the material to obtain a high-strength, high-thermal-conductivity graphite ceramic composite material.

10. The high-strength, high-thermal-conductivity graphite ceramic composite material prepared by the preparation method according to any one of claims 1-9, characterized in that, The prepared graphite ceramic composite material consists of graphite powder, silicon carbide reinforcing network and glassy carbon, wherein the volume percentage of graphite powder is 40-70%, the volume percentage of silicon carbide reinforcing network is 20-40%, and the volume percentage of glassy carbon is 5-10%. The silicon carbide reinforcing network and glassy carbon connect the graphite powder together.

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