WO2007056895A1

WO2007056895A1 - Compact foamed thyrite with high intensity and preparation method of the same

Info

Publication number: WO2007056895A1
Application number: PCT/CN2005/001962
Authority: WO
Inventors: Jinsong Zhang; Xiaoming Cao; Chong Tian; Zhenming Yang
Original assignee: Institute Of Metal Research Chinese Academy Of Sciences
Priority date: 2005-11-18
Filing date: 2005-11-18
Publication date: 2007-05-24

Abstract

The compact foam silicon carbide ceramics material with high strength and the production method of the same are disclosed by the invention. The material is composed by silicon carbide 90-98wt% and silicon 10-2wt%, silicon carbide powder and resin with high carbon-producing ration are mixed to form slurry, foam plastic is cut and soaked in the slurry, which is taken out, removing unnecessary slurry, is treated by semi-solidifying, then high-temperature high-pressure solidifying, the solidified foam body is pyrolized to obtain foam carbon frame with same shape as original foam shape, composed of silicon carbide and pyrolized carbon , opening the centre hole on carbon frame by grinding, the silicon carbide slurry is injected into the centre hole until filling by press injection method, then is pyrolized, carbon in the carbon frame reacts with silicon in gas or liquid phase by silicon infiltration process to generate silicon carbide , and combine with original silicon carbide particles in foam carbon frame, thus to obtain the compact silicon carbide foam ceramics with high strength. The ceramic network obtained by the invention has high density, homogeneous micro structure, smaller amount of silicon residual and high intensity.

Description

High-strength dense foamed silicon carbide ceramic material and preparation method thereof

The present invention relates to a foamed silicon carbide ceramic material, and more particularly to a high strength dense foamed silicon carbide ceramic material and a method of preparing the same.

Background technique

Foam ceramic is a special porous ceramic. The geometrical feature is a three-dimensional connected network formed by connecting the basic closed loops and the basic units. Due to its excellent high temperature resistance, oxidation resistance, acid and alkali corrosion resistance, thermal shock resistance and semiconductor properties, the production and application of foamed silicon carbide ceramics have received extensive attention.

The current foamed silicon carbide ceramics are prepared by the following four methods: powder sintering, solid phase reaction sintering, silicone-containing pyrolysis, and vapor deposition.

The powder sintering process is further divided into two different processes. One is to adjust the silicon carbide powder containing a certain amount of sintering aid and the connecting agent (such as ethyl silicate hydrolyzate, silica sol, etc.) into a slurry of suitable concentration, and then immersed in the polyurethane foam, and solidified and dried. After that, the linker and the polyurethane foam are removed in the range of 200 to 600 °C. Then, the temperature is raised to between 1500 and 2200 ° C for sintering to obtain a foamed silicon carbide ceramic; the other method is to uniformly mix the silicon carbide powder containing the sintering aid with the zeolite foaming agent, and then use Molding or casting method. The blowing agent is removed by melting or gasification, and then sintered at a high temperature to obtain a foamed silicon carbide ceramic.

In the solid phase reaction sintering method, a plant-like foaming agent is uniformly mixed with silicon powder and carbon powder. The foaming agent is obtained by melting or gasifying, and after sintering at a high temperature, a foamed silicon carbide ceramic is obtained.

The silicon-containing resin pyrolysis method is to form a silicone gel precursor into a polymer gel, and to remove the organic solvent in the gel to obtain a foam-like silicon-containing resin, which is fully pre-oxidized and then pyrolyzed to obtain a foamed silicon carbide ceramic.

The vapor deposition method is a method of depositing silicon carbide onto a reticulated carbon fiber braid by chemical vapor deposition to obtain a foamed silicon carbide ceramic.

Excessive manufacturing costs make the vapor deposition process substantially lose the possibility of producing foamed silicon carbide ceramics on an industrial scale. Like other foamed ceramics (such as alumina and zirconia), low strength has been a fundamental problem in the existing methods of preparing various foamed silicon carbide ceramics. In addition to the foamed silicon carbide ceramic prepared by the vapor deposition method, the fundamental reason for the low strength of the foamed silicon carbide ceramic prepared by other methods is that the ceramic ribs constituting the ceramic foam skeleton are not high.

A high intensity proposed by the applicant of the present invention in the Chinese invention patent application (application number 00110479.9) The silicon carbide foam ceramic and the preparation method thereof make the relative enthalpy of the ceramic ribs reach 90% or more, thereby greatly improving the strength of the foamed silicon carbide ceramic. In recent years, research work has found that the residual silicon content in ceramic ribs is too high (generally over 20%), and the uneven distribution limits the improvement of the strength of foamed silicon carbide ceramics, which needs to be further solved.

Summary of the invention

The object of the present invention is to provide a high-strength dense foamed silicon carbide ceramic material and a preparation method thereof. The ceramic ribs prepared by the method have high density (more than 99%) and low residual silicon content (less than 10). %), the structure is uniform, and the strength of the foamed silicon carbide ceramic is significantly improved.

The technical solution of the present invention is a high-strength dense foamed silicon carbide foam ceramic material characterized by: 90% to 98% silicon carbide and 10% to 2% silicon by weight fraction.

The silicon carbide foam ceramic has a polygonal closed ring as a basic unit, and the basic units are connected to each other to form a three-dimensional connected network; the relative density of the ceramic ribs constituting the polygonal closed ring unit is ≥99%, and the average grain size is 50ηιη~10μηι .

The preparation method of the dense silicon carbide foam ceramic is characterized in that: the silicon carbide powder, the high-yield carbon resin is used as a basic raw material, and the foam plastic is used as a template, and the preparation process is as follows:

1) Slurry preparation

The silicon carbide powder, the high-yield carbon resin, the curing agent and the ethanol are mixed in proportion, and the weight percentage between the silicon carbide powder, the high-yield carbon resin and the curing agent is 80 wt% to 30 wt%: 19 wt% to 50 wt%: lwt%~ 20wt%, after mechanical agitation, ball milling time is 0.5~2 hours, filtered through 35~140 mesh screen to obtain slurry, solid matter in the slurry (ie solute, including: silicon carbide powder, high yield carbon rate resin and curing The weight of the agent is 30~80% of the total amount of the paddle _;

2) Dip

Cut the foam into the desired shape and size, evenly immerse it in the slurry, take it out and squeeze out the excess slurry, remove the excess slurry by air blowing and centrifugation, heat the semi-cured, and heat at 50~80 °C. The curing time is 5~60min, and the above dip, extruding and solidification processes are repeated until the weight required for the predetermined volume fraction is 10-60%, and the foamed silicon carbide ceramic precursor is obtained;

3") hot press densification

Put the silicon carbide foam ceramic precursor into a high-pressure container, 'fill with nitrogen or inert gas for high temperature and high pressure curing, the pressure is l~35MPa, the temperature is 50~300°C, the heating rate is 1~5°C, the heat preservation is 5 Minutes to 3 hours, obtaining a dense foamed silicon carbide foam ceramic precursor; The dense silicon carbide foam ceramic precursor is pyrolyzed under the protection of nitrogen or an inert atmosphere, the heating rate is 1~5 ° C per minute, the temperature is raised to 600~1300 ° C, and the temperature is kept for 0.5~2 hours to obtain a foam ceramic carbon skeleton; -

5) Fill the carbon skeleton center hole.

Since the foam is burned off after pyrolysis, a central hole is left in the foamed ceramic carbon skeleton rib, so it is necessary to fill the carbon skeleton center hole to achieve densification. After the center hole of the surface of the carbon skeleton is ground, the filling slurry is pressed into the center hole by a high pressure injection method, and the pressure is 1 to 35 MPa, and the pressure is maintained for 10 minutes to 2 hours, and the dense foamed silicon carbide is obtained by pyrolysis. Carbon skeleton, pyrolysis is carried out under nitrogen or an inert atmosphere or under vacuum, the heating rate is 10 ° C per minute, the temperature is 600 ~ 1300 ° C, and the temperature is maintained for 0.5 to 2 hours;

6) Siliconizing

The pyrolyzed dense silicon carbide foam carbon skeleton is reacted and sintered into silicon, and the silicon infiltration is carried out under nitrogen or an inert atmosphere or under vacuum, and the heating rate is 5 to 15 ° C per minute, and the temperature is 1400 to 2000 ° C. Insulation for 0.5 to 4 hours gives high strength dense foamed silicon carbide ceramic material.

The high-yield carbon-rate resin is selected from one or more of an epoxy resin, a phenol resin, a furfural resin, and a phenolphthalal resin.

The ethanol concentration was 95%. ·

The silicon carbide powder is a silicon carbide powder having an average particle size of 10 ηηι to 15 μηι.

The silicon carbide powder has a weight purity of 95% or more.

The curing agent is one of p-toluenesulfonic acid, penolol, oxalic acid or citric acid.

The foam is a polyurethane foam or a polyether foam, and has a pore diameter of l to 3 mm.

The invention combines a silicon carbide powder with a high-yield carbon-rate resin to prepare a slurry; select a foam of a suitable pore size, and cut it into a desired shape and size, and then immerse it in the slurry, take it out, and use the extrusion, Wind blowing, centrifugation, etc. to remove excess slurry, semi-cured; high temperature, high pressure curing in a high pressure vessel to increase the initial density of the foam ceramic skeleton precursor; the cured foam in a vacuum or inert gas or nitrogen protection furnace Pyrolysis is carried out to obtain a foamy carbon skeleton composed of silicon carbide and pyrolytic carbon in the same shape as the original foam; grinding the central hole of the carbon skeleton, and injecting the silicon carbide slurry into the center hole of the carbon skeleton by injection molding And filling the central hole, and then pyrolyzing; after the silicon infiltration process, the carbon in the carbon skeleton reacts with the gas phase or the liquid phase silicon to form silicon carbide, and combines with the original silicon carbide particles in the foam skeleton to obtain high strength and compactness. Silicon carbide foam ceramics.

The invention has the following beneficial effects:

1. The ceramic ribs have high density, uniform microstructure and less residual silicon.

The method of using the hot-pressed foam ceramic skeleton precursor of the invention not only significantly improves the foam ceramic precursor The initial density of the body ribs also eliminates the problem of microstructure non-uniformity caused by the delamination formed by multiple immersion; and the injection of silicon carbide slurry into the central hole of the foam ceramic carbon skeleton by the injection method, and through the silicon infiltration The reaction is such that the center hole is 3⁄4 full of silicon carbide. The use of these two measures keeps the density of ceramic ribs above 99%, the residual silicon content below 10% (generally below 5%), and the microstructure is very uniform, see Figures 1, 2, and 3. This is a remarkable feature not found in other foamed silicon carbide ceramic preparation methods.

2. High strength.

Due to the large increase in the density of the ceramic ribs, the uniformity of the microstructure, and the large reduction in the amount of residual silicon, the key reason for the low strength of the foamed ceramics is fundamentally solved, and the ratio of the foamed silicon carbide ceramics prepared by the present invention is made. The compressive strength reaches 500 MPa, cm ^{3 1} , which is more than 2 times higher than the compressive strength of the foamed silicon carbide ceramic prepared by the method of the present invention (Application No. 00110479.9), which is prepared by other methods. The foamed silicon carbide ceramic 3⁄4 has a 5 to 10 times higher compressive strength.

DRAWINGS

Figure 1 shows the macroscopic morphology of the foamed silicon carbide ceramic (scale is lmm).

Figure 2 shows the fracture morphology of the foamed silicon carbide ceramic rib (200 μη scale).

Figure 3 shows the microstructure inside the foamed silicon carbide ceramic rib (scale 50 μm).

detailed description

The invention is described in detail below by way of examples.

Example 1

The weight ratio is 60%: 35%: 5% of the average particle size 2μιη silicon carbide powder, ammonia phenolic resin, p-toluenesulfonic acid co-dissolved in absolute ethanol, so that the solids in the slurry: silicon carbide powder, high carbon production The weight of the resin and the curing agent is 40% of the total amount of the slurry, and the ball milling time is 0.5 hour after mechanical stirring, and filtered through a 35 mesh screen to prepare a slurry, and the polyurethane foam having a pore diameter of 1 mm is cut into a required size. Uniformly immersed in the slurry, soaked for 1 minute, taken out and squeezed out excess slurry, air-dried and semi-cured in an oven at a temperature of 50 ° C for 10 minutes. The above process is repeated several times until the desired weight of 30% of the predetermined volume fraction (volume fraction of the silicon carbide ceramic in the finished product) is reached. Then, it was placed in a high-pressure vessel, filled with nitrogen gas to a pressure of 12 MPa, and the temperature was raised to 250 ° C, and the temperature was raised at 2 ° C per minute, and the temperature was maintained for 1 hour to be solidified to obtain a precursor. The precursor was pyrolyzed under argon gas to form a carbon skeleton; wherein the heating rate was 2 ° C per minute, the temperature was raised to 800 Torr, and the temperature was maintained for 0.5 hours. The center hole of the surface of the carbon skeleton is ground, and a slurry having a viscosity of 150 mPa-s is pressed into the center hole in a high-pressure vessel at a pressure of 5 MPa. After holding for 20 minutes, it is pyrolyzed under argon gas to heat up. The rate is 2Ό per minute, the temperature is 800°C, and the temperature is kept for 0.5 hours. After pyrolysis, vacuum silicon is applied, the heating rate is 10°C/min, the temperature is 1800°C, and the temperature is kept for 1 hour. A high-strength dense silicon carbide foam ceramic material having a rib density of 99%, a residual silicon content of 5%, a silicon carbide average grain size of 1.8 μπα, and a foamed silicon carbide ceramic specific compressive strength of 460 ΜΡ3·η ³ ·^, The composition is silicon carbide: 98%, silicon: 2%.

Example 2

The difference from Embodiment 1 is:

The weight ratio is 45%: 50%: 5% of the average particle size of 2μπι silicon carbide powder, epoxy resin (brand number EP0141 - 310), p-toluenesulfonic acid co-dissolved in anhydrous ethanol, so that the solids in the slurry : The weight of silicon carbide powder, high-yield carbon resin and curing agent is 60% of the total amount of slurry. After mechanical agitation, the ball milling time is 1 hour, filtered through a 55 mesh screen to prepare a slurry, and a polyamine with a pore diameter of 2 mm. After the fat foam is cut into the required size, it is evenly immersed in the slurry, soaked for 1 minute, taken out and squeezed out the excess slurry, air-dried, and semi-cured at 50 ° C for 10 minutes. The above process is repeated several times until it reaches The required weight of 20% of the predetermined volume fraction (volume fraction of the silicon carbide ceramic in the finished product). Then, it was placed in a high-pressure vessel, filled with nitrogen gas to a pressure of 10 MPa, and the temperature was raised to 200 ° C, and the temperature was raised to 3 Torr per minute, and the temperature was maintained for 1 hour. Pyrolysis under argon gas to form a carbon skeleton; wherein the heating rate is 2 ° C per minute, the temperature is raised to 900 ° C, and the temperature is maintained for 0.5 hours. The center hole of the surface of the carbon skeleton is ground. In a high-pressure vessel, a slurry having a viscosity of 200 mPa_s is pressed into the center hole at a pressure of 10 MPa. After holding for 40 minutes, the solution is pyrolyzed under argon gas protection at a heating rate of 3 ° C per minute, temperature 900 ° C, holding for 1 hour; after pyrolysis, vacuum siliconizing, reaction temperature 1600 ° C, heating rate of 10 Ό / min, holding for 1 hour, to obtain high strength dense silicon carbide foam ceramic material , the rib density is 99 ° /. The average grain size of silicon carbide is 1.7μηα, and its composition is silicon carbide: 95%, silicon: 5%.

Example 3

The difference from Embodiment 1 is:

Silicon carbide powder, resin (thermosetting phenolic resin 30%, furfural resin 70%) and oxalic acid weight ratio of 70wt%: 20wt%: 10wt%, cosolving thermosetting phenolic resin, furfural resin and oxalic acid in anhydrous ethanol, made a paddle solution, and then uniformly adding silicon carbide powder having an average particle size of 5 μm to the above solution, so that the solid content of the slurry: the weight of the silicon carbide powder, the high-yield carbon resin and the curing agent is 50% of the total amount of the slurry. After mechanical stirring, the ball milling time was 2 hours, and the mixture was filtered through a 75 mesh screen to prepare a paddle. The polyurethane foam with a pore size of 2 mm was cut into the required size and uniformly immersed in the slurry. After taking out, the excess slurry was squeezed out, soaked for 1 minute, and air-dried and semi-cured at 60 ° C for 50 minutes. The above process was repeated several times. , until the desired weight fraction of 40% of the predetermined volume fraction (the volume fraction of the silicon carbide ceramic in the finished product) is reached. It was placed in a high-pressure vessel, filled with nitrogen gas to a pressure of ll MPa, and heated to 230 ° C. The heating rate was 4 ° C per minute and the temperature was maintained for 15 minutes. Pyrolysis under nitrogen protection to form a carbon skeleton; The rate is 3 每 per minute, the temperature is raised to 1000 ° C, and the temperature is kept for 1 hour. The center hole of the carbon skeleton table 3⁄4 is ground, and the slurry with a viscosity of 250 mPa_s is pressed into the center hole in a high pressure vessel at a pressure of 15 MPa. After holding for 1 hour, the slurry is pyrolyzed under a nitrogen atmosphere, and the heating rate is 6 ° C per minute, temperature 1000 ° C, heat preservation for 2 hours; after pyrolysis, siliconization under nitrogen protection, reaction temperature 165 (TC, heating rate of 15 ° C / min, heat preservation for 2 hours, high strength and compact The silicon carbide foam ceramic material has a rib density of 99%, and the silicon carbide has an average grain size of 4.2 μm, and its composition is silicon carbide: 92%, silicon: 8%.

Example 4

The difference from the first embodiment is that - the weight ratio of 60%: 35%: 5% of the average particle size of 1.5 μm silicon carbide powder, boron phenolic resin, and pentazol are co-dissolved in absolute ethanol to make the slurry Medium solids: The weight of silicon carbide powder, high-yield carbon resin and curing agent is 80% of the total volume of the paddle. After mechanical agitation, the ball milling time is 0.5 hours. After filtering through a 95 mesh screen, the slurry is made into a slurry with a pore size of 2 mm. The polyurethane foam is cut into the required size and uniformly immersed in the slurry, soaked for 1 minute, taken out and squeezed out the excess slurry, and the air is semi-cured at 80 ° C for 20 minutes, and the above process is repeated several times until The weight required to reach 50% of the predetermined volume fraction (volume fraction of silicon carbide ceramics in the finished product). It was placed in a high-pressure vessel, filled with argon gas to a pressure of 18 MPa, raised to 260 ° C, and heated at a rate of 5 ° C per minute for 2 hours. Pyrolysis under argon gas to form a carbon skeleton; wherein the heating rate is 4 ° C per minute, the temperature is raised to 600 ° C, and the temperature is maintained for 2 hours. The center hole of the surface of the carbon skeleton is ground. In a high-pressure vessel, a slurry having a viscosity of 300 mPa is pressed into the center hole at a pressure of 35 MPa. After holding for 10 minutes, the solution is pyrolyzed under argon gas protection at a rate of temperature increase. 8 ° C per minute, temperature 1200 ° C, holding for 0.5 hours; after pyrolysis, under silicon protection, siliconizing, reaction temperature 1400 ° C, heating rate of 5 ° C / min, heat preservation for 3 hours, high The dense dense silicon carbide foam ceramic material has a rib density of 100%, and the average grain size of the silicon carbide is Ι.ΐμηα, and its composition is silicon carbide: 90%, silicon: 10%.

Example 5

The difference from Embodiment 1 is:

Silicon carbide powder, resin (60% of thermosetting phenolic resin, 40% of bismuth resin) and penolsine weight ratio of 50wt%: 30wt%: 20wt%, co-solvent of thermosetting phenolic resin and furfural resin with penolidine In the anhydrous ethanol, 'making a slurry solution, and then uniformly adding the silicon carbide powder with an average particle size of 5 μm to the above solution, so that the solid content of the slurry: the weight of the silicon carbide powder, the high-yield carbon resin and the curing agent are 30% of the total amount of pulp, after mechanical agitation, the ball milling time is 1 hour, filtered through a 120 mesh screen to form a slurry, and the polyurethane foam having a pore diameter of 2 mm is cut into a desired size and uniformly immersed in the slurry. Soak for 1 minute, take out the excess slurry, and dry it at 50 °C for 30 minutes. The above process is repeated several times until it reaches 60% of the predetermined volume fraction (SiC silicon carbide in the finished product). The volume fraction of porcelain) is the required weight. Put it into a high-pressure container, fill it with nitrogen gas to bring the pressure to 25 MPa, raise the temperature to 240, and raise the temperature by 2 每 per minute, and heat it for 1 hour. Pyrolysis under argon gas to form a carbon skeleton; wherein the heating rate is 4 ° C per hour, the temperature is raised to 1000 ° C, and the temperature is maintained for 0.5 hours. The center hole of the carbon bone surface is ground. In the high-pressure vessel, the slurry with a viscosity of 180 mPa's is pressed into the center hole at a pressure of 20 MPa. After holding for 2 hours, the solution is pyrolyzed under argon gas protection at a heating rate of 6 ° C per minute, temperature 600 ° C, holding for 2 hours; after pyrolysis, vacuum siliconizing, reaction temperature 550 ° C, heating rate of 15 ° C / min, holding for 1 hour, high strength dense silicon carbide The foamed ceramic material has a rib density of 99%, and the average grain size of the silicon carbide is 3.8 μm, and its composition is silicon carbide: 96%, silicon: 4%.

Example 6

The difference from Embodiment 1 is:

Silicon carbide powder, resin (thermosetting phenolic resin 50%, furfural resin 50%) and citric acid weight ratio 40wt%: 40wt%: 20wt%, cosolving thermosetting phenolic resin and furfural resin with citric acid in absolute ethanol, The slurry solution is prepared, and the silicon carbide powder having an average particle size of ΙΟμπι is uniformly added to the above solution to make the solid content in the slurry: the weight of the silicon carbide powder, the high-yield carbon resin and the curing agent is 80% of the total amount of the slurry. After mechanical agitation, the ball milling time is 2 hours, filtered through a 140 mesh screen to prepare a slurry. The polyurethane foam having a pore size of 3 mm is cut into the required size and uniformly immersed in the slurry, soaked for 1 minute, and taken out. After the excess paddle is squeezed out and air-dried for 10 minutes at 50 ° C, the above process is repeated several times until the desired weight of 10% of the predetermined volume fraction (the volume fraction of the silicon carbide ceramic in the finished product) is reached. It is placed in a high-pressure vessel, filled with nitrogen gas to a pressure of 20 MPa, and heated to 280 ° C. The heating rate is 5 ° C per minute and the temperature is maintained for 1 hour. Pyrolysis under argon gas to form a carbon skeleton; wherein the heating rate is 2 ° C per minute, the temperature is raised to 900 Ό, and the temperature is maintained for 0.5 hours. The center hole of the surface of the carbon skeleton is ground. In a high-pressure vessel, a slurry having a viscosity of 280 mPa_s is pressed into the center hole at a pressure of 30 MPa. After holding for 30 minutes, the slurry is pyrolyzed under argon gas protection at a heating rate of 5 ° C per minute, temperature 800 ° C, heat preservation for 2 hours; after pyrolysis, vacuum silicon infiltration, reaction temperature 1650 ° C, heating rate of 15 ° C / min, heat preservation for 1 hour, to obtain high strength dense silicon carbide foam The ceramic material has a rib density of 100%, and the silicon carbide has an average grain size of 7.2 μm, and its composition is silicon carbide: 94%, silicon: 6%.

Claims

Rights request

1 . A high-strength dense silicon carbide foam ceramic material, characterized in that: by weight fraction, the composition is composed of 90% to 98% silicon carbide and 10% to 2% silicon; ceramics constituting a polygonal closed ring unit The relative density of the ribs is ≥99%, and the average grain size is 50ηπ ~10μπι.

2. A method for preparing a dense silicon carbide foam ceramic according to claim 1, characterized in that: the silicon carbide powder, the high-yield carbon-rate resin as a basic material, and the foam plastic as a template, the preparation process is as follows:

1) Slurry preparation

The silicon carbide powder, the high-yield carbon resin, the curing agent and the ethanol are mixed in proportion, and the weight percentage between the silicon carbide powder, the high-yield carbon resin and the curing agent is 80 wt% to 30 wt%: 19 wt% to 50 wt%: lwt%~ 20wt%, after mechanical agitation, ball milling time. 0.5~2 hours, filtered through 35~140 mesh screen to obtain slurry, the weight of the solid in the slurry is 30~80% of the total amount of slurry _;

2) Dip.

Cut the foam into the desired shape and size, evenly immerse it in the slurry, take it out and squeeze out the excess slurry, remove the excess slurry by air blowing and centrifugation, heat 'semi-cured, heating temperature 50~80°C The curing time is 5~60min, and the dip, extruding and solidification processes are repeated until the weight required for the predetermined volume fraction is 10-60%, and the foamed silicon carbide ceramic precursor is obtained;

3) Hot press densification

The silicon carbide foam ceramic precursor is placed in a high-pressure vessel, filled with nitrogen or an inert gas for high-temperature, high-pressure curing, pressure is l~35MPa, temperature is 50~300°C, heating rate is 1~5°C, and heat is kept for 5 minutes. ~ 3 hours, obtaining a dense foamed silicon carbide foam ceramic precursor;

4) Pyrolysis.

The dense silicon carbide foam ceramic precursor is pyrolyzed under the protection of nitrogen or an inert atmosphere, the heating rate is 1~5 °C per minute, the temperature is raised to 600~1300 °C, and the temperature is kept for 0.5~2 hours to obtain a foam ceramic carbon skeleton;

5) Fill the carbon skeleton center hole

After the center hole of the surface of the carbon skeleton is ground, the filling slurry is pressed into the center hole by a high pressure injection method, and the pressure is 1 to 35 MPa, and the pressure is maintained for 10 minutes to 2 hours, and the dense foamed silicon carbide is obtained by pyrolysis. Carbon skeleton, pyrolysis is carried out under nitrogen or an inert atmosphere or under vacuum, the heating rate is 1~10 °C per minute, the temperature is 600~1300 °C, and the temperature is 0.5-2 hours;

6) Siliconizing The pyrolyzed dense silicon carbide foam carbon skeleton is reacted and sintered into silicon, and the silicon infiltration is carried out under nitrogen or an inert atmosphere or under vacuum, and the heating rate is 5 to 15 ° C per minute, and the temperature is 1400 to 2000 ° C. Insulation for 0.5 to 4 hours, to obtain a dense dense foamed silicon carbide ceramic material.

3. The method for preparing a dense silicon carbide foam ceramic material according to claim 2, wherein: the high-yield carbon resin is selected from the group consisting of epoxy resin, phenol resin, furfural resin, and phenolic furfural resin. .

A method of producing a dense silicon carbide ceramic foam material according to claim 2, wherein the ethanol concentration is 95%.

The method for preparing a dense silicon carbide ceramic material according to claim 2, wherein the silicon carbide powder is a silicon carbide powder having an average particle size of 10 ηηι to 15 μηι.

The method for producing a dense foamed silicon carbide ceramic material according to claim 2, wherein the silicon carbide powder has a purity of 95% or more.

The method for preparing a dense foamed silicon carbide ceramic material according to claim 2, wherein the curing agent is one of p-toluenesulfonic acid, penolol, oxalic acid or citric acid.

The method for preparing a dense foamed silicon carbide ceramic material according to claim 2, wherein the foam is a polyurethane foam or a polyether foam, and has a pore diameter of l to 3 mm.