CN112209720B - Carbon/silicon carbide bicontinuous phase composite material and preparation method thereof - Google Patents

Carbon/silicon carbide bicontinuous phase composite material and preparation method thereof Download PDF

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CN112209720B
CN112209720B CN202011076751.3A CN202011076751A CN112209720B CN 112209720 B CN112209720 B CN 112209720B CN 202011076751 A CN202011076751 A CN 202011076751A CN 112209720 B CN112209720 B CN 112209720B
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silicon carbide
carbon
composite material
carbide powder
phase composite
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CN112209720A (en
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廖寄乔
李军
邓华峰
龚智
李丙菊
石磊
刘学文
王跃军
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Hunan Jinbo Carbon Co ltd
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    • C04B35/56—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides
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Abstract

The invention relates to a carbon/silicon carbide bicontinuous phase composite material and a preparation method thereof. The composite material is composed of recrystallized silicon carbide and pyrolytic carbon, wherein the mass fraction of the recrystallized silicon carbide in the composite material is 80-83%: the mass fraction of the pyrolytic carbon in the composite material is as follows: 17-20%, and the porosity of the composite material is less than or equal to 5%. The preparation method comprises the steps of mixing the silicon carbide powder with a pore-forming agent and a forming agent to obtain a mixture, carrying out compression molding on the mixture to obtain a silicon carbide green body, drying and sintering the silicon carbide green body to obtain a silicon carbide green body with the porosity of 25-35%, and carrying out chemical vapor deposition and pyrolytic carbon decomposition on the silicon carbide green body to obtain the carbon/silicon carbide bicontinuous phase composite material. The obtained carbon/silicon carbide bicontinuous phase composite material has good high-temperature mechanical property, good thermal shock resistance and excellent erosion resistance.

Description

Carbon/silicon carbide bicontinuous phase composite material and preparation method thereof
Technical Field
The invention relates to a carbon/silicon carbide bicontinuous phase composite material and a preparation method thereof, belonging to the technical field of preparation of composite materials.
Background
The silicon carbide ceramic has hardness second to that of diamond, and has outstanding physicochemical properties of small thermal expansion coefficient, high thermal conductivity, good chemical stability, high wear resistance, good mechanical property and oxidation resistance at high temperature, and the like.
In the actual preparation process, the most main forming modes of the silicon carbide ceramic are as follows: reaction sintered silicon carbide (RBSiC), recrystallized silicon carbide (RSiC), and precursor conversion (PIP);
the RBSiC process can prepare SiC parts with complex shapes, and the sintering temperature is low, but the RBSiC has low purity and abundant silicon, so the high-temperature performance is poor. The RSiC is formed by forming fine SiC powder and evaporating and condensing SiC fine powder on coarse particles at high temperature to form a sintering process, and has the highest purity of over 99 percent, so that the RSiC has the advantages of a lot of pure silicon carbide, such as excellent high-temperature strength retention capacity, oxidation resistance, thermal shock resistance and the like. However, since the raw materials of the SiC powder and the binder are SiC powder and the binder does not shrink in volume during sintering, the binder is decomposed during sintering, so that the porosity of the binder is about 15%, the strength of the binder is reduced, the high-temperature service life of the binder is shortened, the defect of leakage is caused, and the application of the binder in the high-temperature field is limited.
The precursor conversion process (PIP) is a process of converting a liquid precursor, mainly used as a composite material, and compounding the composite material with other reinforcement substrates, such as the prior patents N101033137A and CN101037825A, in which a carbon fiber preform is prepared, and then pyrolytic carbon and organic SiC are alternately deposited by a chemical vapor infiltration method to form a multi-layer substrate, so as to obtain a C/C-SiC composite material. However, the cost of the carbon fiber and its prefabricated body is high, and the period of the compounding process is long, so that the price of the composite material is high.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a carbon/silicon carbide bicontinuous phase composite material which has high purity, low cost and excellent high-temperature mechanical property, thermal shock resistance and erosion resistance and a preparation method thereof.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention relates to a carbon/silicon carbide bicontinuous phase composite material, which comprises the following components in percentage by weight: the composite material consists of recrystallized silicon carbide and pyrolytic carbon, wherein the mass fraction of the recrystallized silicon carbide in the composite material is 80-83%; the mass fraction of the pyrolytic carbon in the composite material is as follows: 17-20%, wherein the porosity of the composite material is less than or equal to 5%, and the apparent porosity is less than or equal to 1%.
In the carbon/silicon carbide bicontinuous phase composite material provided by the invention, the silicon carbide phase and the carbon phase are both continuous phases and are tightly combined, so that the carbon/silicon carbide bicontinuous phase composite material has excellent high-temperature mechanical properties and long service life.
The invention relates to a preparation method of a carbon/silicon carbide bicontinuous phase composite material, which comprises the steps of mixing silicon carbide powder with a pore-forming agent and a forming agent to obtain a mixture, carrying out compression molding on the mixture to obtain a silicon carbide green body, drying and sintering the silicon carbide green body to obtain a silicon carbide green body with the porosity of 25-35 percent, preferably 26-33 percent, and carrying out chemical vapor deposition pyrolysis on the silicon carbide green body to obtain the carbon/silicon carbide bicontinuous phase composite material with the porosity of less than or equal to 5 percent.
In the preparation method, a recrystallized silicon carbide blank is prepared by adopting a recrystallization mode, the porosity of the silicon carbide blank is controlled to be 25-35% by adding a pore-forming agent, and then pyrolytic carbon is deposited, so that the carbon/silicon carbide bicontinuous phase composite material is obtained. In the preparation method of the invention, the control of the porosity of the silicon carbide blank to 25-35% is crucial, if the porosity is too small, the deposited carbon cannot form a continuous phase, and the mechanical property of the material is reduced, and if the porosity is too large, the doped carbon is too much, the silicon carbide is not easy to form a continuous phase, the strength of the recrystallized silicon carbide blank is reduced, the production difficulty is increased, the thermal conductivity and the thermal shock resistance of the product are reduced, and the service life of the product is shortened.
Preferably, the silicon carbide powder consists of silicon carbide powder A with the particle size of 0.1-10 microns, silicon carbide powder B with the particle size of 10-50 microns and silicon carbide powder C with the particle size of 50-100 microns, and the mass ratio of the silicon carbide powder A to the silicon carbide powder C is as follows: silicon carbide powder B: 20-30% of silicon carbide powder C: 10-20: 50-70.
In a further preferred scheme, the silicon carbide powder consists of silicon carbide powder A with the particle size of 0.5-0.8 μm, silicon carbide powder B with the particle size of 10-20 μm and silicon carbide powder C with the particle size of 45-55 μm, and the mass ratio of the silicon carbide powder A: silicon carbide powder B: 20-30% of silicon carbide powder C: 15-20: 55-65.
In the invention, the combination of the silicon carbide powders with three particle sizes is adopted, and the highest apparent density can be obtained under the combination of the particle sizes, so that the performance of the finally formed material is optimal. Because the size and the grain diameter are matched for the production of recrystallized silicon carbide, on one hand, the function of bonding large-grain silicon carbide is achieved by utilizing the volatile condensation of small-grain silicon carbide powder; on the other hand, because the silicon carbide particles are extremely hard and are not easy to compress and compact, the density of the green body can be effectively improved by matching the particle sizes. Through tests, the particle size combination can reach higher apparent density, so that the strength of the silicon carbide blank is improved, the thermal shock resistance is improved, the service life of the product is prolonged, and a foundation is laid for the excellent performance of the two-phase composite material.
In a preferred scheme, the pore-forming agent is sodium carbonate and polyethylene glycol, wherein the addition amount of the sodium carbonate is 2wt% -4 wt% of the mass of the silicon carbide powder, and the addition amount of the polyethylene glycol is 0.5wt% -5 wt% of the mass of the silicon carbide powder.
By adding the pore-forming agent with the content, the porosity of the silicon carbide green body can be controlled to be 25-35%.
In a preferable scheme, the forming agent is sodium cellulose, and the addition amount of the sodium cellulose is 0.5wt% -5 wt% of the mass of the silicon carbide powder.
In the actual operation process, silicon carbide powder, a pore-forming agent and a forming agent are mixed by a mixer, then water is added, and the mixture is obtained through mixing kneading, ageing and vacuum mud refining.
In a preferable scheme, the drying mode is microwave drying, the temperature of the microwave drying is 80-100 ℃, and the time is 8-16 h.
According to the invention, the silicon carbide green body is subjected to microwave drying, the deformation and cracking of the silicon carbide green body can be avoided by adopting the microwave drying, the yield is improved, and in addition, the final composite material has more excellent performance.
Preferably, the sintering process comprises the steps of vacuumizing, controlling the furnace pressure to be less than 10Pa, heating to 2350-2450 ℃ at the heating rate of 3-5 ℃/min, introducing argon till the furnace pressure is 800-1000 Pa, keeping the temperature for 4-5 h, cooling to 800 ℃ along with the furnace, stopping vacuumizing, and continuing to cool along with the furnace.
In order to obtain high-purity recrystallized silicon carbide, the whole process of the invention adopts negative pressure sintering, high negative pressure is adopted in the temperature rising stage, so that impurities can be completely volatilized, and when the sintering temperature is reached, argon is filled, sintering is controlled under the condition of lower negative pressure, and the optimal environment of evaporation-condensation-recrystallization is created for the silicon carbide.
The inventor finds that if the negative pressure is too high when the sintering temperature is reached, the accuracy of an infrared thermometer is disturbed, and silicon carbide steam is easily pumped out of a furnace body along with a vacuum pump to influence recrystallization and sintering.
Certainly, if the silicon carbide is sintered under normal pressure in a protective atmosphere, impurity components in the silicon carbide are not easy to discharge, and the temperature measurement accuracy of the infrared thermometer is also interfered by the excessively concentrated protective atmosphere.
In a preferred embodiment, the density of the silicon carbide green body is 2.1g/cm3～2.4g/cm3。
In a preferred embodiment, the chemical vapor deposition process comprises: with C3H6Or natural gas is carbon source gas, N2Controlling carbon source gas and N as diluent gas2The volume ratio is 1: 1-5, controlling the surface temperature of the silicon carbide blank to be 900-1200 ℃, the furnace pressure to be 1-10 kPa, the deposition time to be 60-120 h, and cooling along with the furnace after the deposition is finished.
In a preferable scheme, the density of the carbon/silicon carbide bicontinuous phase composite material is 2.6-2.9 g/cm3。
The principle and the advantages are as follows:
the invention discloses a carbon/silicon carbide bicontinuous phase structure composite material, which adopts a high-purity silicon carbide prefabricated blank body, wherein two kinds of high-purity silicon carbide coarse powder and high-activity silicon carbide micro powder are mixed, are subjected to anaerobic sintering at the high temperature of 2350-2450 ℃ after being formed, and are subjected to vapor deposition pyrolytic carbon at the temperature of 900-1200 ℃. Because the material has high purity, the carbon and the silicon carbide are both continuous phases and the two-phase combination is tight, the material has excellent high-temperature mechanical property and long service life.
The carbon/silicon carbide bicontinuous phase composite material prepared by the invention has the technical index that the volume density is 2.6-2.9 g/cm3Porosity of 1.2-4.8%, apparent porosity of 0.1-0.9%, Young's modulus of 300-330 GPa, breaking strength of 100-130 MPa at 1200 deg.C, and thermal expansion coefficient of 2.2-3.5 × 10-6/K, the thermal conductivity coefficient is 28-32W/(m.K), the acid and alkali resistance is 1-14, the thermal shock resistance is tested by an air quenching method, and the repeated thermal cycle times are 40-60. Therefore, the material has high Young's modulus, high thermal conductivity, low expansion coefficient, good high-temperature mechanical property, good thermal shock resistance and excellent erosion resistanceThe material is an ideal material for containers required in the fields of silicon smelting, lithium battery anode and cathode material sintering and the like.
Detailed Description
Example l
Firstly, taking 20 wt% of silicon carbide powder (0.5 particle), 15 wt% of silicon carbide powder (30 micron) and 65 wt% of silicon carbide powder (85 micron) as a mixture, adding 3 wt% of sodium carbonate, 4wt% of polyethylene glycol and 3 wt% of sodium cellulose, mixing for 1h, adding 25 wt% of purified water, kneading for 2h, aging for 24h, and performing vacuum mud refining for three times. Forming by extrusion, drying for 12h at 100 ℃ in a microwave drying furnace to obtain a silicon carbide green body, placing the silicon carbide green body in a sintering furnace, controlling the furnace pressure to be less than 10Pa, then heating to 2450 ℃ at the heating rate of 4.5 ℃/min, and introducing argon until the furnace pressure is 950 Pa; and (5) preserving heat and sintering for 5 hours to obtain the silicon carbide green body with the porosity of 32 percent. And then carrying out CVI carbon gas phase deposition on the porous silicon carbide blank, wherein the process comprises the following steps: using natural gas as carbon source, N2Controlling carbon source gas and N as diluent gas2Is 1: 3; the surface temperature of the silicon carbide blank body is controlled to be 1200 ℃, the furnace pressure is controlled to be 10kPa, and the deposition time is controlled to be 120 hours. And obtaining the carbon/silicon carbide bicontinuous phase structure composite material.
The finished sample of this example was tested for performance and the results were as follows: bulk density 2.89g/cm3Porosity of 2.8%, apparent porosity of 0.5%, Young's modulus of 326GPa, breaking strength of 128MPa at 1200 deg.C, and thermal expansion coefficient of 2.2 × 10-6The thermal conductivity coefficient is 31W/(m.K), the acid and alkali resistance is 1-14, the thermal shock resistance is tested by an air quenching method, the repeated thermal cycle times are 60, and the impurity content of the product is 0.03%.
Example 2
The process of this example is the same as example 1 except that some process parameters are changed: and (3) performing CVI carbon vapor deposition, wherein the surface temperature of the silicon carbide blank is controlled to be 1000 ℃, and the deposition time is 100 hours.
The same performance tests as in example l were carried out on the finished test specimens of this example, with the following results: bulk density 2.76g/cm3Porosity 4.6%, apparent porosity 0.8%, Young's modulus 308GPa, flexural strength at 1200 deg.C 106MPa, and thermal expansion coefficient 2.6 × 10-6The thermal conductivity coefficient is 28W/(m.K), the acid and alkali resistance is 1-14, the thermal shock resistance is tested by an air quenching method, the repeated thermal cycle times are 46, and the impurity content of the product is 0.03%.
Example 3
The process of this example is the same as example 1 except that some process parameters are changed: the raw and auxiliary materials adopt 30 wt% of silicon carbide powder (0.8 particle), 20 wt% of silicon carbide powder (20 micron), 50 wt% of silicon carbide powder (55 micron) as a mixture, 2wt% of sodium carbonate, 0.5wt% of polyethylene glycol and 0.5wt% of sodium cellulose are added, and a silicon carbide blank with the porosity of 26% is prepared.
The same performance tests as in example l were carried out on the finished test specimens of this example, with the following results: bulk density 2.87g/cm3Porosity of 3.1%, apparent porosity of 0.6%, Young's modulus of 320GPa, breaking strength of 117MPa at 1200 deg.C, and thermal expansion coefficient of 3.5 × 10-6The thermal conductivity coefficient is 32W/(m.K), the acid and alkali resistance is 1-14, the thermal shock resistance is tested by an air quenching method, the repeated thermal cycle times are 55, and the impurity content of the product is 0.03%.
Example 4
The process of this example is the same as example 3, except that some process parameters are changed: performing CVI carbon vapor deposition to control carbon source gas and N2Is 1: 1, controlling the surface temperature of the silicon carbide blank to be 1000 ℃, and depositing for 100 hours.
The same performance tests as in example l were carried out on the finished test specimens of this example, with the following results: bulk density 2.65g/cm3Porosity 4.7%, apparent porosity 0.8%, Young's modulus 302GPa, flexural strength at 1200 deg.C 102MPa, and thermal expansion coefficient 2.6 × 10-6The thermal conductivity coefficient is 30W/(m.K), the acid and alkali resistance is 1-14, the thermal shock resistance is tested by an air quenching method, the repeated thermal cycle times are 42, and the impurity content of the product is 0.03%.
Example 5
The process of this example is the same as example 3, except that some process parameters are changed: the raw and auxiliary materials are as follows by weight percent: 20 wt% of silicon carbide powder (0.8 particle), 15 wt% of silicon carbide powder (15 micron) and 65 wt% of silicon carbide powder (50 micron) are mixed materials, and the mixture is added3 wt% of sodium carbonate, 2wt% of polyethylene glycol and 2wt% of sodium cellulose, mixing for 1h, and adding 23 wt% of purified water; drying at 90 deg.C for 12 h. And (3) preserving heat for 5 hours at 2350 ℃ in argon atmosphere to obtain the silicon carbide blank with the porosity of 30%. And then carrying out CVI carbon gas phase deposition on the porous silicon carbide blank in a chemical gas phase deposition furnace, wherein the process comprises the following steps: c3H6Is carbon source gas, N2Controlling carbon source gas and N as diluent gas2Is 1: 2; the surface temperature of the silicon carbide blank body is controlled to be 1000 ℃, the furnace pressure is controlled to be 5kPa, and the deposition time is controlled to be 120 hours. And obtaining the carbon/silicon carbide bicontinuous phase structure composite material.
The same performance tests as in example l were carried out on the finished test specimens of this example, with the following results: bulk density 2.86g/cm3Porosity of 3.5%, apparent porosity of 0.7%, Young's modulus of 310GPa, flexural strength of 112MPa at 1200 deg.C, and thermal expansion coefficient of 2.8 × 10-6The thermal conductivity coefficient is 29W/(m.K), the acid and alkali resistance is 1-14, the thermal shock resistance is tested by an air quenching method, the repeated thermal cycle times are 55, and the impurity content of the product is 0.029%.
Comparative example 1
Comparative example 1 the other process was the same as in example 1 except that some of the following process parameters were varied: using natural gas as carbon source gas, N2Controlling carbon source gas and N as diluent gas2Is 1: 3; controlling the surface temperature of the silicon carbide blank body to be 800 ℃, the furnace pressure to be 8kPa, and the deposition time to be 100 hours. Thus obtaining the carbon/silicon carbide bicontinuous phase structure composite material of the invention.
The same performance tests as in example l were carried out on the finished test specimens of comparative example 1, with the following results: bulk density 2.45g/cm3Porosity of 14.5%, apparent porosity of 3.2%, Young's modulus of 228GPa, breaking strength of 78MPa at 1200 deg.C, and thermal expansion coefficient of 2.9 × 10-6The thermal conductivity coefficient is 15W/(m.K), the acid and alkali resistance is 1-14, the thermal shock resistance is tested by an air quenching method, the repeated thermal cycle times are 10, and the impurity content of the product is 0.029%.
Comparative example 2
Comparative example 2 the process was otherwise the same as in example 1 except that the following parameters were varied: the proportion of the silicon carbide powder is 5wt% of silicon carbide powder (0.5 particle), 5wt% of silicon carbide powder (10 microns) and 90 wt% of silicon carbide powder (45 microns).
The same performance tests as in example l were carried out on the finished sample of comparative example 2, with the following results: bulk density 2.49g/cm3Porosity of 13.6%, apparent porosity of 3.0%, Young's modulus of 235GPa, breaking strength of 82MPa at 1200 deg.C, and thermal expansion coefficient of 2.0 × 10-6The thermal conductivity coefficient is 18W/(m.K), the acid and alkali resistance is 1-14, the thermal shock resistance is tested by an air quenching method, the repeated thermal cycle times are 12, and the impurity content of the product is 0.03%.
Comparative example 3
The other conditions were the same as in example 1 except that no pore-forming agent was added during the preparation of the silicon carbide green body: sodium carbonate and polyethylene glycol, resulting in a silicon carbide body with a porosity of 14%. Then CVI carbon gas phase deposition is carried out to obtain the carbon/silicon carbide composite material.
The same performance tests as in example l were carried out on the finished sample of comparative example 3, with the following results: bulk density 2.95g/cm3Porosity of 1.7%, apparent porosity of 0.3%, Young's modulus of 308GPa, breaking strength of 112MPa at 1200 deg.C, and thermal expansion coefficient of 3.9 × 10-6The material has the advantages of high thermal conductivity coefficient of 26W/(m.K), acid and alkali resistance of 1-14, thermal shock resistance tested by an air quenching method, 42 times of repeated thermal cycle and 0.028% of impurity content of the product.
Comparative example 4
The other conditions are the same as those in example 1, and only 8 wt% of sodium carbonate and 7 wt% of polyethylene glycol are added in the preparation process of the silicon carbide green body, so that the silicon carbide green body with the porosity of 46% is obtained. Then CVI carbon gas phase deposition is carried out for 160 hours until the carbon/silicon carbide composite material is compact, and the carbon/silicon carbide composite material is obtained.
The same performance tests as in example l were carried out on the finished test specimens of comparative example 4, with the following results: bulk density 2.35g/cm3Porosity of 8.0%, apparent porosity of 1.5%, Young's modulus of 276GPa, breaking strength of 75MPa at 1200 deg.C, and thermal expansion coefficient of 2.1 × 10-6The thermal conductivity coefficient is 22W/(m.K), the acid and alkali resistance is 1-14, the thermal shock resistance is tested by an air quenching method, the repeated thermal cycle times are 11, and the impurity content of the product is 0.028%.
Comparative example 5
The other conditions were the same as in example 1 except that the sintering process of the silicon carbide green body was: the whole process adopts the furnace pressure less than 10 Pa.
The same performance tests as in example l were carried out on the finished test specimens of comparative example 5, with the following results: bulk density 2.35g/cm3Porosity of 8.0%, apparent porosity of 1.5%, Young's modulus of 216GPa, breaking strength of 55MPa at 1200 deg.C, and thermal expansion coefficient of 1.8 × 10-6The thermal conductivity coefficient is 18W/(m.K), the acid and alkali resistance is 1-14, the thermal shock resistance is tested by an air quenching method, the repeated thermal cycle times are 6, and the impurity content of the product is 0.015%.
Comparative example 6
The other conditions were the same as in example 1 except that the sintering process of the silicon carbide green body was: the whole process adopts argon atmosphere and is sintered under normal pressure.
The same performance tests as in example l were carried out on the finished test specimens of this comparative example 6, with the following results: bulk density 2.88g/cm3Porosity of 2.7%, apparent porosity of 0.5%, Young's modulus of 315GPa, flexural strength of 112MPa at 1200 deg.C, and thermal expansion coefficient of 2.6 × 10-6The thermal conductivity coefficient is 29W/(m.K), the acid and alkali resistance is 3-10, the thermal shock resistance is tested by an air quenching method, the repeated thermal cycle times are 50, and the impurity content of the product is 1.6%.

Claims (9)

1. A preparation method of a carbon/silicon carbide bicontinuous phase composite material is characterized by comprising the following steps: mixing silicon carbide powder with a pore-forming agent and a forming agent to obtain a mixture, performing compression molding on the mixture to obtain a silicon carbide green body, drying and sintering the silicon carbide green body to obtain a silicon carbide green body with the porosity of 25-35%, and performing chemical vapor deposition pyrolysis on the silicon carbide green body to obtain a carbon/silicon carbide bicontinuous phase composite material with the porosity of less than or equal to 5%;
the carbon/silicon carbide bicontinuous phase composite material consists of recrystallized silicon carbide and pyrolytic carbon, wherein the mass fraction of the recrystallized silicon carbide in the carbon/silicon carbide bicontinuous phase composite material is 80-83%; the mass fraction of pyrolytic carbon in the carbon/silicon carbide bicontinuous phase composite material is 17-20%, and the porosity of the carbon/silicon carbide bicontinuous phase composite material is less than or equal to 5%.
2. The method for preparing a carbon/silicon carbide bicontinuous phase composite material as claimed in claim 1, wherein:
the silicon carbide powder consists of silicon carbide powder A with the particle size of 0.1-10 microns, silicon carbide powder B with the particle size of 10-50 microns and silicon carbide powder C with the particle size of 50-100 microns, and the mass ratio of the silicon carbide powder A to the silicon carbide powder C is as follows: silicon carbide powder B: and (3) silicon carbide powder C = 20-30: 10-20: 50-70.
3. The method for preparing a carbon/silicon carbide bicontinuous phase composite material as claimed in claim 1, wherein:
the silicon carbide powder consists of silicon carbide powder A with the particle size of 0.5-0.8 mu m, silicon carbide powder B with the particle size of 10-20 mu m and silicon carbide powder C with the particle size of 45-55 mu m, and the mass ratio of the silicon carbide powder A to the silicon carbide powder C is as follows: silicon carbide powder B: and (3) silicon carbide powder C = 20-30: 15-20: 55-65.
4. The method for preparing a carbon/silicon carbide bicontinuous phase composite material as claimed in claim 1, wherein:
the pore-forming agent is sodium carbonate and polyethylene glycol, wherein the addition amount of the sodium carbonate is 2-4 wt% of the mass of the silicon carbide powder, and the addition amount of the polyethylene glycol is 0.5-5 wt% of the mass of the silicon carbide powder.
5. The method for preparing a carbon/silicon carbide bicontinuous phase composite material as claimed in claim 1, wherein:
the forming agent is sodium cellulose, and the addition amount of the sodium cellulose is 0.5-5 wt% of the mass of the silicon carbide powder.
6. The method for preparing a carbon/silicon carbide bicontinuous phase composite material as claimed in claim 1, wherein: the drying mode is microwave drying, the temperature of the microwave drying is 80-100 ℃, and the time is 8-16 h.
7. The method for preparing a carbon/silicon carbide bicontinuous phase composite material as claimed in claim 1, wherein:
the sintering process comprises the following steps: vacuumizing, controlling the furnace pressure to be less than 10Pa, heating to 2350-2450 ℃ at the heating rate of 3-5 ℃/min, simultaneously filling argon until the furnace pressure is 800-1000 Pa, preserving heat for 4-5 h, cooling to 800 ℃ along with the furnace, stopping vacuumizing, and continuing cooling along with the furnace.
8. The method for preparing a carbon/silicon carbide bicontinuous phase composite material as claimed in claim 1, wherein:
the density of the silicon carbide green body is 2.1g/cm3～2.4 g/cm3。
9. The method for preparing a carbon/silicon carbide bicontinuous phase composite material as claimed in claim 1, wherein:
the chemical vapor deposition process comprises the following steps: with C3H6Or natural gas is carbon source gas, N2Controlling carbon source gas and N as diluent gas2The volume ratio is 1: 1-5, controlling the surface temperature of the silicon carbide blank to be 900-1200 ℃, the furnace pressure to be 1-10 kPa, the deposition time to be 60-120 h, and cooling along with the furnace after the deposition is finished.
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