Method for preparing controllable resistance porous silicon carbide ceramic by inorganic pore-forming method

Abstract

The invention provides a method for preparing resistance-controllable porous silicon carbide ceramic by an inorganic pore-forming method, and belongs to the technical field of silicon carbide ceramic preparation, the raw materials comprise a matrix material, a pore-forming agent and a coating material, the matrix material comprises 100 parts of silicon carbide micro powder, 0.5-3 parts of boron carbide micro powder, 5-15 parts of an adhesive, 0.5-3 parts of a surfactant and 0.5-2 parts of a dispersant, the pore-forming agent is silicon dioxide hollow spheres, the coating material is nano carbon black, and the preparation method comprises the steps of weighing and granulating, coating with the pore-forming agent, mixing raw materials, preparing a green body, sintering and post-processing. The surface of the silicon dioxide hollow sphere is coated with the nano carbon black, the silicon carbide is generated through in-situ reaction, the residual silicon dioxide amount or residual carbon amount of the porous silicon carbide ceramic is changed by controlling the amount of the coated nano carbon black, and then the resistivity of the porous silicon carbide ceramic is regulated and controlled; meanwhile, mechanical properties such as compression strength and bending strength, oxidation resistance, corrosion resistance and chemical stability are improved.

Description

Technical Field

[0001] This invention relates to the field of silicon carbide ceramic preparation technology, specifically to a method for preparing controllable resistivity porous silicon carbide ceramics using an inorganic pore-forming method. Background Technology

[0002] Silicon carbide ceramics possess excellent properties such as high hardness, high strength, high temperature resistance, oxidation resistance, corrosion resistance, wear resistance, thermal shock resistance, and good chemical stability, and have been widely used in fields such as power, electronics, communications, chemistry, and energy. In recent years, with the rapid development of semiconductor technology, the demand for porous silicon carbide ceramics has been increasing.

[0003] Adding pore-forming agents is a common method for preparing porous silicon carbide ceramics. Organic pore-forming agents, such as those prepared by adding polymethyl methacrylate, polystyrene, and polyethylene oxide, have been widely used in industrial applications. However, due to the significant density difference between silicon carbide ceramic powder and organic pore-forming agents, stratification easily occurs during mixing, resulting in the need for further improvement in the uniformity, stability, and consistency of pore size and distribution, and microstructure of the prepared porous silicon carbide ceramics. Inorganic pore-forming agents, such as silica, have a smaller density difference with silicon carbide, and hold promise for producing porous silicon carbide ceramics with better uniformity, stability, and consistency in pore size and distribution and microstructure. With the continuous development of silica hollow sphere preparation technology, the technology for preparing silica hollow spheres with controllable particle size, pore size, and purity has gradually matured, and the cost has continued to decrease, laying the foundation for the preparation of porous silicon carbide ceramics by adding silica hollow spheres.

[0004] However, when silicon carbide ceramics contain a large amount of silicon dioxide, it will reduce the high temperature resistance, acid and alkali corrosion resistance, chemical stability, and electrical conductivity of porous silicon carbide ceramics. Therefore, it is urgent to further study how to reduce the amount of silicon dioxide in porous silicon carbide ceramics and minimize the adverse effects of silicon dioxide on the properties of porous ceramic materials. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing controllable resistivity porous silicon carbide ceramics using an inorganic pore-forming method, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing controllable resistivity porous silicon carbide ceramics using an inorganic pore-forming method. The raw materials for preparing porous silicon carbide ceramics include a matrix material, a pore-forming agent, and a coating material. By mass parts, the matrix material includes 100 parts of silicon carbide micro powder, 0.5-3 parts of boron carbide micro powder, 5-15 parts of binder, 0.5-3 parts of surfactant, and 0.5-2 parts of dispersant; the pore-forming agent is hollow silica spheres; and the coating material is nano-carbon black.

[0008] The preparation method includes the following steps:

[0009] S1. Weigh the above matrix material according to the ratio, add deionized water, ball mill to obtain silicon carbide ceramic slurry, spray granulation to obtain granulated powder;

[0010] S2, the pore-forming agent is processed to a rough surface, and then the surface of the pore-forming agent is coated with carbon powder using a coating material. After the coating is completed, the pore-forming agent is dried and sieved. The material that passes through the sieve is the coated pore-forming agent.

[0011] S3, mix the granulated powder with the required amount of coated pore-forming agent evenly to obtain the mixture;

[0012] S4. The mixture is molded or isostatically pressed to obtain a green body. The green body is then dried to prevent cracking caused by rapid evaporation of moisture during sintering.

[0013] S5, the green body is placed in a sintering furnace for sintering, so that the nano carbon black coated on the surface of the silica hollow sphere reacts with the silica in situ to generate silicon carbide, and a porous silicon carbide ceramic sintered body is produced.

[0014] S6 involves grinding and polishing the porous silicon carbide sintered body to produce porous ceramic products.

[0015] Preferably, in step S1, the D of silicon carbide micropowder in the matrix material... 50 =0.45±0.2μm; D of boron carbide micro powder 50 =1.50±1μm; the surfactant is stearic acid or fatty acid glycerides; the dispersant is tetramethylammonium hydroxide or polyacrylic acid; the binder is phenolic resin, polyacryl alcohol or carboxymethyl cellulose.

[0016] Preferably, in step S1, the amount of deionized water is 0.9-1.5 times the mass of silicon carbide micro powder, the ball milling time is 8-20 hours, the moisture content of the granulated powder is 0.5-1.5%, and the mass ratio of particles with a size of 60-200 mesh in the granulated powder is greater than 90%.

[0017] Preferably, the detailed steps of step S2 include: A1, adding the pore-forming agent to the sugar coating machine, starting the sugar coating machine, and allowing the pore-forming agents to rub against each other for 1-5 hours to roughen the surface; A2, using an ethanol solution containing phenolic resin and carbon black to spray and humidify the pore-forming agent, coating the surface of the pore-forming agent with carbon powder; A3, drying the coated pore-forming agent at 30-50°C, passing it through a 40-mesh sieve, and retaining the material passing through the sieve.

[0018] If the pore-forming agent becomes too wet and agglomerates during the spray humidification process, the spraying of the ethanol mixture should be stopped. Instead, the sugar coating machine should be rotated to allow some of the ethanol to evaporate. After evaporation, the spraying of the ethanol mixture should continue until all the required ethanol mixture has been sprayed.

[0019] Preferably, the purity of the silica hollow spheres is not less than 99%.

[0020] The size and content of silica hollow spheres are determined based on the pore size and porosity of the porous ceramic. To prepare porous silicon carbide ceramics with larger pore sizes, larger silica hollow spheres should be selected. To prepare porous silicon carbide ceramics with higher porosity, the amount of silica hollow spheres added should be appropriately increased.

[0021] Preferably, the phenolic resin in the ethanol solution has a mass fraction of 1-10%, making it slightly viscous so that the carbon powder can adhere to the surface of the pore-forming agent; the nano-carbon black has a mass fraction of 1-10%, and the nano-carbon black has a D... 50 No more than 20nm.

[0022] Preferably, the mass ratio of nano carbon black to pore-forming agent is 0.2-0.6:1.

[0023] Preferably, the mass ratio of nano carbon black to pore-forming agent is 0.4-0.6:1.

[0024] Preferably, in step S4, the green body forming pressure is not less than 180 MPa to ensure that the green body has a certain strength, and then the green body is dried at 50-80℃ for 1-5 hours.

[0025] Preferably, in step S5, the green blank is placed in a vacuum sintering furnace and sintered. The temperature is raised to 1700-1900℃ and held for 1-6 hours to allow the nano carbon black coated on the surface of the silica hollow sphere to react in situ with the silica to generate silicon carbide. Then the temperature is raised to 2100-2200℃ and held for 1-7 hours to obtain a porous silicon carbide ceramic sintered body.

[0026] The beneficial effects of the above-described technical solution of the present invention are as follows:

[0027] 1. This invention controls the amount of nano-carbon black coated on the surface of the silica hollow sphere pore-forming agent, thereby changing the amount of residual silica or residual carbon in the porous silicon carbide ceramic, and thus adjusting the resistivity of the porous silicon carbide ceramic.

[0028] 2. By coating the surface of the pore-forming agent with nano carbon black, it reacts with silicon dioxide in situ to generate silicon carbide, which can not only regulate resistivity, but also improve mechanical properties such as compressive strength and flexural strength, as well as oxidation resistance, corrosion resistance and chemical stability.

[0029] 3. Coating the surface of hollow silica spheres with nano-carbon black can make the carbon black more evenly distributed in the green body, solving the problem of uneven distribution caused by the agglomeration of added carbon black, which leads to uneven product phase composition and microstructure, thereby improving the performance consistency of the product.

[0030] 4. Compared with organic pore-forming agents, the density difference between silicon dioxide and silicon carbide is significantly reduced. Therefore, silicon dioxide hollow spheres can be more uniformly distributed in the green body, resulting in porous silicon carbide ceramics with more uniform phase composition and microstructure, which is beneficial to improving the consistency of product performance. Detailed Implementation

[0031] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0032] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0033] Example 1

[0034] A method for preparing controllable resistivity porous silicon carbide ceramics using an inorganic pore-forming method includes the following steps:

[0035] S1. Weigh 100 parts of silicon carbide micro powder, 1 part of boron carbide micro powder, 0.5 parts of stearic acid, 0.5 parts of polyacrylic acid, and 10 parts of phenolic resin, add them to a drum ball mill, add 110 parts of deionized water, and ball mill for 10 hours to obtain silicon carbide ceramic slurry; then spray granulate the silicon carbide slurry to obtain granulated powder. The moisture content of the granulated powder is measured to be 0.9%, and the mass ratio of granulated powder with a particle size of 60-200 mesh is 92%.

[0036] S2, add 10 parts of silica hollow sphere pore-forming agent with a median particle size of 80μm to the sugar coating machine, start the sugar coating machine and run it for 3 hours to make the pore-forming agents rub against each other and make the surface rough; add 4 parts of carbon black and 1.5 parts of phenolic resin to 70 parts of ethanol, mix well, and then continue to rotate the sugar coating machine to spray and humidify the pore-forming agent with ethanol solution to coat the surface of the pore-forming agent with a thin layer of carbon powder. After coating, dry at 40℃ and pass through a 40-mesh sieve. The material that passes through the sieve is the coated pore-forming agent, which is reserved for later use.

[0037] S3, uniformly mix the silicon carbide granulated powder obtained in step S1 with the required amount of the coated pore-forming agent prepared in step S2.

[0038] S4. The mixture obtained in step S3 is molded with a molding pressure of 180 MPa to prepare a porous silicon carbide ceramic green body. Then, the green body is dried at 60°C for 3 hours to avoid cracking caused by rapid evaporation of moisture during sintering.

[0039] S5. The green body obtained in step S4 is placed in a vacuum sintering furnace and heated to 1800℃ and held for 2 hours to allow the silica hollow spheres to react in situ with the nano carbon powder coated on their surface to generate silicon carbide; finally, the temperature is raised to 2150℃ and held for 2 hours to obtain a porous silicon carbide ceramic sintered body.

[0040] S6 involves grinding, polishing, and other post-processing of the porous silicon carbide ceramic sintered body to obtain porous ceramic products of the required specifications, shapes, and sizes.

[0041] Testing revealed that the obtained porous silicon carbide ceramic had an open porosity of 12.4% and a resistivity of 1.8 × 10⁻⁶. 7 Ω·cm.

[0042] Example 2

[0043] A method for preparing controllable resistivity porous silicon carbide ceramics using an inorganic pore-forming method includes the following steps:

[0044] S1. Weigh 100 parts of silicon carbide micro powder, 1 part of boron carbide micro powder, 0.5 parts of stearic acid, 0.5 parts of polyacrylic acid, and 10 parts of phenolic resin, add them to a drum ball mill, add 110 parts of deionized water, and ball mill for 10 hours to obtain silicon carbide ceramic slurry; then spray granulate the silicon carbide slurry to obtain granulated powder. The moisture content of the granulated powder is measured to be 0.9%, and the mass ratio of granulated powder with a particle size of 60-200 mesh is 92%.

[0045] S2, add 10 parts of silica hollow sphere pore-forming agent with a median particle size of 80μm to the sugar coating machine, start the sugar coating machine and run it for 3 hours to make the pore-forming agents rub against each other and make the surface rough; add 6 parts of carbon black and 2.2 parts of phenolic resin to 80 parts of ethanol, mix evenly, and then continue to rotate the sugar coating machine to spray and humidify the pore-forming agent with ethanol solution to coat the surface of the pore-forming agent with a thin layer of carbon powder. After coating, dry at 40℃ and pass through a 40-mesh sieve. The material that passes through the sieve is the coated pore-forming agent, which is reserved for later use.

[0046] S3, uniformly mix the silicon carbide granulated powder obtained in step S1 with the required amount of the coated pore-forming agent prepared in step S2.

[0047] S4. The mixture obtained in step S3 is molded with a molding pressure of 180 MPa to prepare a porous silicon carbide ceramic green body. Then, the green body is dried at 60°C for 3 hours to avoid cracking caused by rapid evaporation of moisture during sintering.

[0048] S5. The green body obtained in step S4 is placed in a vacuum sintering furnace and heated to 1800℃ and held for 2 hours to allow the silica hollow spheres to react in situ with the nano carbon powder coated on their surface to generate silicon carbide; finally, the temperature is raised to 2150℃ and held for 2 hours to obtain a porous silicon carbide ceramic sintered body.

[0049] S6 involves grinding, polishing, and other post-processing of the porous silicon carbide ceramic sintered body to obtain porous ceramic products of the required specifications, shapes, and sizes.

[0050] Testing revealed that the obtained porous silicon carbide ceramic had an open porosity of 13.5% and a resistivity of 1.8 × 10⁻⁶. 3 Ω·cm.

[0051] Example 3

[0052] A method for preparing controllable resistivity porous silicon carbide ceramics using an inorganic pore-forming method includes the following steps:

[0053] S1. Weigh 100 parts of silicon carbide micro powder, 1 part of boron carbide micro powder, 0.5 parts of stearic acid, 0.5 parts of polyacrylic acid, and 10 parts of phenolic resin, add them to a drum ball mill, add 110 parts of deionized water, and ball mill for 10 hours to obtain silicon carbide ceramic slurry; then spray granulate the silicon carbide slurry to obtain granulated powder. The moisture content of the granulated powder is measured to be 0.9%, and the mass ratio of granulated powder with a particle size of 60-200 mesh is 92%.

[0054] S2, add 10 parts of silica hollow sphere pore-forming agent with a median particle size of 80μm to the sugar coating machine, start the sugar coating machine and run it for 3 hours to make the pore-forming agents rub against each other and make the surface rough; add 6 parts of carbon black and 5 parts of phenolic resin to 125 parts of ethanol, mix evenly, and then continue to rotate the sugar coating machine to spray and humidify the pore-forming agent with ethanol solution to coat the surface of the pore-forming agent with a thin layer of carbon powder. After coating, dry at 40℃ and pass through a 40-mesh sieve. The material that passes through the sieve is the coated pore-forming agent, which is reserved for later use.

[0055] S3, uniformly mix the silicon carbide granulated powder obtained in step S1 with the required amount of the coated pore-forming agent prepared in step S2.

[0056] S4. The mixture obtained in step S3 is molded with a molding pressure of 180 MPa to prepare a porous silicon carbide ceramic green body. Then, the green body is dried at 60°C for 3 hours to avoid cracking caused by rapid evaporation of moisture during sintering.

[0057] S5. The green body obtained in step S4 is placed in a vacuum sintering furnace and heated to 1800℃ and held for 2 hours to allow the silica hollow spheres to react in situ with the nano carbon powder coated on their surface to generate silicon carbide; finally, the temperature is raised to 2150℃ and held for 2 hours to obtain a porous silicon carbide ceramic sintered body.

[0058] S6 involves grinding, polishing, and other post-processing of the porous silicon carbide ceramic sintered body to obtain porous ceramic products of the required specifications, shapes, and sizes.

[0059] The obtained porous silicon carbide ceramic was found to have an open porosity of 14.8% and a resistivity of 37 Ω·cm.

[0060] Comparative Example 1

[0061] A method for producing porous silicon carbide ceramics includes the following steps:

[0062] The technical solution is described in Example 2.

[0063] The difference is that step S2 is omitted, and the pore-forming agent is not coated with nano-carbon black. In step S3, the pore-forming agent is directly mixed with the granulating powder.

[0064] Everything else is the same as in Example 2.

[0065] Experiments revealed silica residue in the furnace shell and vacuum channel. This is likely due to the melting and volatilization of silica in the green billet at high temperatures, which can damage the sintering furnace and reduce its service life.

[0066] Testing revealed that the obtained porous silicon carbide ceramic had an open porosity of 18.5% and a resistivity of 3.9 × 10⁻⁶. 8 Ω·cm.

[0067] Comparative Example 2

[0068] A method for preparing porous silicon carbide ceramics includes the following steps:

[0069] The technical solution is described in Example 2.

[0070] The difference is that in step S2, the pore-forming agent is not pre-ground, but is directly sprayed with ethanol mixture to humidify it.

[0071] Everything else is the same as in Example 2.

[0072] Experiments revealed that due to the smooth surface of the silica hollow spheres, the uniformity of the nano-carbon black coating was poor, and the pore-forming agent was prone to agglomeration. Furthermore, different products from the same batch exhibited fluctuations in porosity and resistivity, indicating a decrease in product performance consistency.

[0073] Testing revealed that the average open porosity of multiple porous silicon carbide ceramics was approximately 13.3%, and the resistivity was 3.5 × 10⁻⁶. 3 Ω·cm.

[0074] Comparative Example 3

[0075] A method for preparing porous silicon carbide ceramics includes the following steps:

[0076] The technical solution is described in Example 2.

[0077] The difference is that in step S2, the process of coating nano-carbon black is not used. Instead, in step S3, nano-carbon black is directly mixed with silicon carbide granulation powder and pore-forming agent until uniform.

[0078] Everything else is the same as in Example 2.

[0079] Experiments revealed that due to the tendency of nano-carbon black to agglomerate, direct mixing makes it difficult to achieve uniform mixing of nano-carbon black with silicon carbide granulation powder and pore-forming agents. This results in poor uniformity of carbon black distribution within the green body, manifested as significant fluctuations in porosity and resistivity in batch products. Even after cutting larger cubic products into smaller squares, the porosity and resistivity of different squares showed considerable differences. This indicates that directly mixing nano-carbon black with silicon carbide granulation powder and pore-forming agents does not easily guarantee uniform and consistent product performance.

[0080] Testing revealed that the average open porosity of multiple porous silicon carbide ceramics was 14.1%, and the resistivity was 4.6 × 10⁻⁶. 3 Ω·cm.

[0081] Results analysis:

[0082] 1. By comparing Examples 1, 2 and 3, it can be found that increasing the content of nano carbon black or phenolic resin used for coating can react more with silicon dioxide to form silicon carbide, reduce the residual silicon dioxide in the product, or increase the residual carbon content in the product and reduce the resistivity of the sample.

[0083] 2. By comparing Example 2 with Comparative Example 1, it can be seen that although the silica pore-forming agent melts and volatilizes at high temperature, there is still an unavoidable silica residue in the sample without the addition of nano carbon black, and therefore the resistivity is still relatively high.

[0084] 3. As can be seen from the comparison between Example 2 and Comparative Example 2, pre-grinding the pore-forming agent with a sugar coating machine can obtain a pore-forming agent with a relatively rough surface, which improves the coating effect of nano carbon black, helps to reduce the agglomeration of the pore-forming agent, and thus reduces the resistivity of the product.

[0085] 4. As can be seen from the comparison between Example 2 and Comparative Example 3, compared with mixing nano carbon black with silicon carbide granulated powder and pore-forming agent, nano carbon black coating pore-forming agent can distribute carbon black more evenly and can contact silicon dioxide more evenly and fully, react better to generate silicon carbide, reduce silicon dioxide residue, and thus reduce the resistivity of the product.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing controllable resistivity porous silicon carbide ceramics using an inorganic pore-forming method, characterized in that, The raw materials for preparing porous silicon carbide ceramics include matrix materials, pore-forming agents, and coating materials. By mass, the matrix materials include 100 parts of silicon carbide micro powder, 0.5-3 parts of boron carbide micro powder, 5-15 parts of binder, 0.5-3 parts of surfactant, and 0.5-2 parts of dispersant; the pore-forming agent is hollow silica spheres; and the coating material is nano-carbon black. The preparation method includes the following steps: S1. Weigh the above matrix material according to the ratio, add deionized water, ball mill to obtain silicon carbide ceramic slurry, spray granulation to obtain granulated powder; S2, the pore-forming agent is processed to a rough surface, and then the surface of the pore-forming agent is coated with carbon powder using a coating material. After the coating is completed, the pore-forming agent is dried and sieved. The material that passes through the sieve is the coated pore-forming agent. S3, mix the granulated powder with the required amount of coated pore-forming agent evenly to obtain the mixture; S4. The mixture is molded or isostatically pressed to obtain a green body. The green body is then dried to prevent cracking caused by rapid evaporation of moisture during sintering. S5, the green body is placed in a sintering furnace for sintering, so that the nano carbon black coated on the surface of the silica hollow sphere reacts with the silica in situ to generate silicon carbide, and a porous silicon carbide ceramic sintered body is produced. S6 involves grinding and polishing the porous silicon carbide sintered body to produce porous ceramic products.

2. The method for preparing controllable resistivity porous silicon carbide ceramics using the inorganic pore-forming method according to claim 1, characterized in that, In step S1, the D of silicon carbide micro powder in the matrix material 50 =0.45±0.2μm; D of boron carbide micro powder 50 =1.50±1μm; the surfactant is stearic acid or fatty acid glycerides; the dispersant is tetramethylammonium hydroxide or polyacrylic acid; the binder is phenolic resin, polyacryl alcohol or carboxymethyl cellulose.

3. The method for preparing controllable resistivity porous silicon carbide ceramics using the inorganic pore-forming method according to claim 1, characterized in that, In step S1, the amount of deionized water is 0.9-1.5 times the mass of silicon carbide micro powder, the ball milling time is 8-20 hours, the moisture content of the granulated powder is 0.5-1.5%, and the mass ratio of particles with a size of 60-200 mesh in the granulated powder is greater than 90%.

4. The method for preparing controllable resistivity porous silicon carbide ceramics using the inorganic pore-forming method according to claim 1, characterized in that, The detailed steps of step S2 include: A1, adding the pore-forming agent to the sugar coating machine, starting the sugar coating machine, and allowing the pore-forming agents to rub against each other for 1-5 hours to roughen the surface; A2, using an ethanol solution containing phenolic resin and carbon black to spray and humidify the pore-forming agent, coating the surface of the pore-forming agent with carbon powder; A3, drying the coated pore-forming agent at 30-50℃, passing it through a 40-mesh sieve, and retaining the material passing through the sieve.

5. The method for preparing controllable resistivity porous silicon carbide ceramics using the inorganic pore-forming method according to claim 1 or 4, characterized in that, The purity of the hollow silica spheres is not less than 99%.

6. The method for preparing controllable resistivity porous silicon carbide ceramics using the inorganic pore-forming method according to claim 4, characterized in that, In the ethanol solution, the mass fraction of phenolic resin is 1-10%; the mass fraction of nano-carbon black is 1-10%, and the D of the nano-carbon black is... 50 No more than 20nm.

7. The method for preparing controllable resistivity porous silicon carbide ceramics using the inorganic pore-forming method according to claim 6, characterized in that, The mass ratio of nano carbon black to pore-forming agent is 0.2-0.6:

1.

8. The method for preparing controllable resistivity porous silicon carbide ceramics using the inorganic pore-forming method according to claim 7, characterized in that, The mass ratio of nano carbon black to pore-forming agent is 0.4-0.6:

1.

9. The method for preparing controllable resistivity porous silicon carbide ceramics using the inorganic pore-forming method according to claim 1, characterized in that, In step S4, the green body forming pressure is not less than 180 MPa to ensure that the green body has a certain strength, and then the green body is dried at 50-80℃ for 1-5 hours.

10. The method for preparing controllable resistivity porous silicon carbide ceramics using the inorganic pore-forming method according to claim 1, characterized in that, In step S5, the green body is placed in a vacuum sintering furnace and sintered. The temperature is raised to 1700-1900℃ and held for 1-6 hours to allow the nano carbon black coated on the surface of the silica hollow spheres to react in situ with the silica to generate silicon carbide. Then the temperature is raised to 2100-2200℃ and held for 1-7 hours to obtain a porous silicon carbide ceramic sintered body.