High-purity porous silicon carbide ceramics and preparation method and application thereof

Abstract

The present invention relates to a high-purity porous silicon carbide ceramic and its preparation method and application. The preparation method comprises the following steps: 1) preparing a first silicon carbide ceramic green body; the first silicon carbide ceramic green body is composed of silicon carbide ceramic particles with a purity of ≥99.9% and a pore-forming agent; 2) high-temperature sintering to obtain a second silicon carbide ceramic green body; the sintering temperature is greater than the burnout temperature of the pore-forming agent; the second silicon carbide ceramic green body contains only one component, silicon carbide ceramic particles; 3) depositing a silicon carbide film on the pore walls and pore ribs of the second silicon carbide ceramic green body, coating the silicon carbide ceramic particles therein, and obtaining a high-purity porous silicon carbide ceramic. The technical problem to be solved by the present invention is how to improve the purity of porous silicon carbide ceramics so that its purity can reach more than 99.9% and its strength can reach 50MPa, meeting its application requirements in wafer processing, liquid crystal panel processing and flexible screen processing in the semiconductor industry.

Description

Technical Field

[0001] The invention belongs to the technical field of porous ceramics, and in particular relates to a high-purity porous silicon carbide ceramic and a preparation method and application thereof. Background Art

[0002] Wafer processing, liquid crystal panel processing and flexible screen processing in the semiconductor industry all require porous ceramic suction cups. Some of the processes have extremely high requirements for the purity of porous silicon carbide ceramic suction cups, requiring their purity to reach more than 99.9% to avoid impurities in the suction cups from contaminating the materials and affecting their use effects. However, the porous silicon carbide ceramics in the prior art mainly include pressureless sintered silicon carbide, glass-bonded silicon carbide and the like. Since sintering aids such as boron carbide and yttrium oxide are added to the pressureless sintered silicon carbide porous ceramics during the preparation process to ensure the sintering of silicon carbide ceramics, the silicon carbide porous ceramics prepared by this process are not of high purity and cannot meet the influence of wafer processing on material purity; and because the glass-bonded silicon carbide porous ceramics contain glass phase materials such as silicon and aluminum, their purity is also not high and cannot meet the requirements of material purity for wafer processing. Summary of the invention

[0003] The main purpose of the present invention is to provide a high-purity porous silicon carbide ceramic and its preparation method and application. The technical problem to be solved is how to improve the purity and strength of porous silicon carbide ceramics so that its purity can reach more than 99.9% and its strength is ≥50MPa, meeting its application requirements in wafer processing, liquid crystal panel processing and flexible screen processing in the semiconductor industry, so as to be more suitable for practical use.

[0004] The purpose of the present invention and the technical problem to be solved are achieved by adopting the following technical solutions. According to a method for preparing high-purity porous silicon carbide ceramics proposed by the present invention, the method comprises the following steps:

[0005] 1) preparing a first silicon carbide ceramic green body; the first silicon carbide ceramic green body is composed of silicon carbide ceramic particles with a purity of ≥99.9% and a pore-forming agent;

[0006] 2) high-temperature sintering to obtain a second silicon carbide ceramic green body; the sintering temperature is greater than the burnout temperature of the pore-forming agent; the second silicon carbide ceramic green body contains only one component, namely silicon carbide ceramic particles;

[0007] 3) depositing a silicon carbide film on the pore walls and pore rib surfaces of the second silicon carbide ceramic green body to cover the silicon carbide ceramic particles therein, thereby obtaining a high-purity porous silicon carbide ceramic.

[0008] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0009] Preferably, in the aforementioned preparation method, the pore-forming agent comprises an organic monomer and an organic auxiliary agent; or, in addition to the organic monomer and the organic auxiliary agent, the pore-forming agent further comprises carbon powder and / or carbon black.

[0010] Preferably, in the aforementioned preparation method, the high temperature sintering is to burn out all the organic monomers and organic additives; or, the high temperature sintering is to burn out all the organic monomers and organic additives, as well as carbon powder and / or carbon black; the temperature of the high temperature sintering is 400-800°C.

[0011] Preferably, in the aforementioned preparation method, the deposition is chemical vapor deposition; the raw gas for the deposition is monomethyltrichlorosilane with a flow rate of 0.7 L / min; hydrogen is used as a catalyst; the volume ratio of hydrogen to monomethyltrichlorosilane is 10:1; and the deposition temperature is 1100-1300°C.

[0012] Preferably, in the aforementioned preparation method, the purity of the silicon carbide film is ≥99.9%.

[0013] Preferably, in the aforementioned preparation method, the thickness of the silicon carbide film is 20 to 40 microns.

[0014] The purpose of the present invention and the solution to the technical problem are also achieved by adopting the following technical solutions. A high-purity porous silicon carbide ceramic proposed in the present invention comprises:

[0015] A silicon carbide porous body comprising only one component, silicon carbide;

[0016] A silicon carbide coating layer is coated on the pore wall surface or pore rib surface of the pores in the silicon carbide porous body; the thickness of the silicon carbide coating layer is 20 to 40 microns;

[0017] The silicon carbide content of the high-purity porous silicon carbide ceramic is ≥99.9% and the strength is ≥50MPa.

[0018] Preferably, the aforementioned high-purity porous silicon carbide ceramic is prepared according to the aforementioned method for preparing the high-purity porous silicon carbide ceramic.

[0019] The purpose of the present invention and the technical problem solved by the present invention are also achieved by the following technical solutions: The present invention proposes an application of a high-purity porous silicon carbide ceramic in the field of wafer processing, liquid crystal panel processing or flexible screen processing technology.

[0020] The purpose of the present invention and the technical problem solved by the present invention are also achieved by the following technical solutions: According to the ceramic suction cup proposed by the present invention, the material is high-purity porous silicon carbide ceramic with a purity of ≥99.9 and a strength of ≥50MPa.

[0021] By means of the above technical solution, the high-purity porous silicon carbide ceramic and its preparation method and application proposed by the present invention have at least the following advantages:

[0022] The high-purity porous silicon carbide ceramic and its preparation method and application proposed in the present invention firstly use high-purity silicon carbide micropowder and pore-forming agent to uniformly mix to prepare ceramic slurry, and prepare the ceramic slurry into a first silicon carbide ceramic green body by conventional methods in the prior art, such as gel injection, dry pressing, isostatic pressing, grouting and other processes; then, it is subjected to high-temperature sintering treatment to remove binder and pyrolysis, and the components added as pore-forming agent in the first silicon carbide ceramic green body are completely burned out to obtain a porous silicon carbide ceramic with a certain strength, that is, a second silicon carbide ceramic green body; finally, the second silicon carbide ceramic green body is placed in a chemical vapor deposition silicon carbide device, and a layer of high-purity silicon carbide coating with a thickness of 20 to 40 microns is deposited on the pore wall surface and the pore rib surface of the pore by a chemical vapor deposition process, and the porous silicon carbide ceramic is completely coated by the deposited dense silicon carbide coating, so that the purity and strength of the porous silicon carbide ceramic are further improved, thereby obtaining a high-purity porous silicon carbide ceramic that can meet the use requirements. The high-purity porous silicon carbide ceramics prepared by the technical solution of the present invention have extremely high purity and good strength. When applied to wafer processing, liquid crystal panel processing or flexible screen processing in the semiconductor industry, the influence of impurity components in the suction cup on the material can be avoided.

[0023] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a physical photograph of the second silicon carbide ceramic green body in Example 1 of the present invention;

[0025] Figure 2 is an electron microscope image of the second silicon carbide ceramic green body in Example 1 of the present invention;

[0026] Figure 3 is an XRD pattern of the second silicon carbide ceramic green body in Example 1 of the present invention;

[0027] Figure 4 This is an electron microscope image of the high-purity porous silicon carbide ceramic in Example 1 of the present invention. DETAILED DESCRIPTION

[0028] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of a high-purity porous silicon carbide ceramic and its preparation method and application proposed in accordance with the present invention, its specific implementation method, structure, characteristics and effects, in combination with the accompanying drawings and preferred embodiments.

[0029] The present invention provides a method for preparing high-purity porous silicon carbide ceramics, which comprises the following steps:

[0030] First, a first silicon carbide ceramic green body is prepared. A ceramic slurry is first prepared, and then the slurry is prepared into a first silicon carbide ceramic green body; the first silicon carbide ceramic green body can be prepared by various methods of porous ceramics, such as slip casting, molding, gel casting, etc., which are not specifically limited in the present invention.

[0031] When preparing the ceramic slurry, the selection of materials requires that the first silicon carbide ceramic green body is composed of silicon carbide ceramic particles with a purity of ≥99.9% and a pore-forming agent, that is, the ceramic slurry contains only one type of silicon carbide ceramic particles in addition to the pore-forming agent. The pore-forming agent mentioned here is a broad pore-forming agent, which includes both a narrow pore-forming agent and a burn-out agent, an organic monomer and a cross-linking agent, a ceramic binder, and various additives added to improve the performance of the ceramic slurry such as dispersion, etc. In addition to providing a porous structure for silicon carbide ceramics, the pore-forming agent also provides a temporary binder for silicon carbide powder; through the temporary bonding of the pore-forming agent, the silicon carbide powder is bonded together and then prepared into the first silicon carbide ceramic green body so that it can maintain a certain shape for subsequent processes.

[0032] The ceramic slurry can be prepared in a variety of systems, which are not specifically limited in the present invention. Examples of the ceramic slurry systems and green body forming methods that can be selected are as follows:

[0033] The ceramic slurry may include: 15-25wt% deionized water, 30-70wt% high-purity silicon carbide powder (purity 99.9%), 2-10wt% carbon black, 3-8wt% acrylamide, 0.3-0.8wt% N'N-methylenebisacrylamide, 0.1-0.5wt% polyvinylpyrrolidone (PVP for short) and 3-7wt% tetramethylammonium hydroxide solution, which are ball-milled in a ball mill to fully disperse SiC and C powder to form a ceramic slurry; then, initiators such as ammonium persulfate, hydrogen peroxide, sodium bisulfite or azobenzene are added to the ceramic slurry to solidify the ceramic slurry to form a network structure, and the silicon carbide powder is coated therein to form a gel containing SiC and carbon black; the specific embodiment 1 of the present invention adopts this ceramic slurry system.

[0034] Alternatively, the ceramic slurry may include: 20-30% anhydrous ethanol, 30-50wt% high-purity silicon carbide powder, 20%-40%wt% phenolic resin, 3-6wt% tetramethylammonium hydroxide is added for dispersion, ball milled for 18 hours, mixed evenly to obtain ceramic slurry, placed in an oven at 130°C for curing, and dried for 12 hours; Specific embodiment 2 of the present invention adopts this ceramic slurry system.

[0035] Alternatively, the ceramic slurry may include: 20-30% anhydrous ethanol, 30-50wt% high-purity silicon carbide powder, 5%-25%wt% carbon powder, 5-20wt% phenolic resin as raw materials, 3-6wt% tetramethylammonium hydroxide and 0.1-0.5wt% polyvinyl pyrrolidone as dispersants, ball milling for 18 hours, mixing evenly to obtain ceramic slurry, placing it in an oven at 80°C for 12 hours to dry, sieving to obtain a powder containing a phenolic resin binder, and then dry-pressing the powder; specific embodiment 3 of the present invention adopts this ceramic slurry system.

[0036] Secondly, the first silicon carbide ceramic green body is placed in a high temperature furnace for high temperature sintering to obtain a second silicon carbide ceramic green body. The high temperature sintering is to burn out all the organic monomers and organic additives; or, the high temperature sintering is to burn out all the organic monomers and organic additives, as well as carbon powder and / or carbon black. The purpose of high temperature sintering is, on the one hand, to thermally debond the material used as a pore-forming agent in the ceramic slurry, so that after the pore-forming agent is burned out, its original position can form a large number of pores, so that the silicon carbide ceramic forms a porous structure, which is convenient for the CVD process. The organic precursor can enter the pores and deposit in the pores to form a SiC coating, and the SiC coating covers the silicon carbide ceramic particles; on the other hand, it is to sinter the silicon carbide powder so that even if it contains only one component of silicon carbide, it can form a ceramic green body with a certain strength; by controlling the temperature, time and other process parameters of high temperature sintering, the strength of the second silicon carbide ceramic green body can be 6 to 11 MPa.

[0037] The present invention limits the sintering temperature to be greater than the burnout temperature of the pore-forming agent, with the purpose of completely burning out the pore-forming agent added to the ceramic slurry during sintering, so that the second silicon carbide ceramic green body contains and only contains one component, silicon carbide, thereby ensuring the purity of the second silicon carbide ceramic green body, so that the second silicon carbide ceramic green body contains only one component, silicon carbide.

[0038] Depending on the different pore-forming agents in the ceramic slurry, there are different requirements for the high-temperature sintering temperature; preferably, the high-temperature sintering temperature is 400-800°C.

[0039] Finally, a silicon carbide film is deposited on the pore walls and pore rib surfaces of the second silicon carbide ceramic green body.

[0040] The deposition of the silicon carbide film is achieved by chemical vapor deposition. The second silicon carbide ceramic green body obtained by high-temperature sintering is placed in a chemical vapor deposition silicon carbide device, at 1100-1300°C, with monomethyltrichlorosilane as the raw material, and its flow rate is 0.7L / min; hydrogen is used as a catalyst; the volume ratio of hydrogen to monomethyltrichlorosilane is 10:1; the deposition temperature is preferably 1200°C. A layer of dense high-purity silicon carbide film with a purity of ≥99.9% is deposited on the pore wall surface and pore rib surface of the porous silicon carbide ceramic green body, and the silicon carbide ceramic particles are coated therein, which can improve the strength of the porous silicon carbide ceramic, and obtain a high-purity porous silicon carbide ceramic whose purity and strength meet the application requirements at the same time.

[0041] In order to ensure the strength and porosity of high-purity porous silicon carbide ceramics, the present invention preferably has a thickness of 20 to 40 microns for the high-purity silicon carbide film. If the thickness of the deposited silicon carbide film is too thin, it is difficult to improve the strength to meet the requirements of using porous ceramics as suction cups, and if the thickness of the deposited silicon carbide film is too thick, it will affect the pore size and porosity on the one hand, and increase the cost on the other hand.

[0042] The present invention also provides a high-purity porous silicon carbide ceramic, which comprises:

[0043] A silicon carbide porous body comprising only one component, silicon carbide;

[0044] A silicon carbide coating layer is coated on the pore wall surface or pore rib surface of the pores in the silicon carbide porous body; the thickness of the silicon carbide coating layer is 20 to 40 microns;

[0045] The silicon carbide content of the high-purity porous silicon carbide ceramic is ≥99.9% and the strength is ≥50MPa.

[0046] The high-purity porous silicon carbide ceramic is preferably prepared by the aforementioned method.

[0047] The present invention also proposes an application of high-purity porous silicon carbide ceramics in the technical fields of wafer processing, liquid crystal panel processing or flexible screen processing.

[0048] The present invention also provides a ceramic suction cup, which is prepared using the above-mentioned high-purity porous silicon carbide ceramic, and the material of the ceramic suction cup is high-purity porous silicon carbide ceramic with a purity of ≥99.9 and a strength of ≥50MPa.

[0049] The present invention will be further described below in conjunction with specific embodiments, but this should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by technicians in this field based on the above-mentioned contents of the present invention still fall within the scope of protection of the present invention.

[0050] Unless otherwise specified, the materials, reagents, etc. involved below are all commercially available products well known to those skilled in the art; unless otherwise specified, the methods described are all methods well known in the art. Unless otherwise defined, the technical terms or scientific terms used should have the common meanings understood by ordinary technicians in the field to which the present invention belongs.

[0051] Embodiment 1:

[0052] This embodiment prepares a high-purity porous silicon carbide ceramic, and the specific steps are as follows:

[0053] 1) Preparation of ceramic slurry: 19.3wt% of deionized water, 66wt% of high-purity silicon carbide powder (purity 99.9%), 2.11wt% of carbon black, 5.3wt% of acrylamide, 0.5wt% of N'N-methylenebisacrylamide, 0.19wt% of polyvinylpyrrolidone (PVP) and 6.6wt% of tetramethylammonium hydroxide solution (aqueous solution with a mass concentration of 10wt%) were weighed in percentage by mass; the above raw materials were added into a ball mill and ball milled for 24 hours to fully disperse SiC powder and C powder to form a slurry.

[0054] 2) Preparing a first silicon carbide ceramic green body: adding ammonium persulfate initiator to the ceramic slurry prepared in step 1), wherein the amount of initiator added is 0.1wt% of the ceramic slurry; then sealing the slurry and allowing it to stand to solidify the ceramic slurry to form a network structure, in which the silicon carbide powder is encapsulated to form a gel containing SiC powder and C black powder; then placing the aforementioned gel in a constant temperature and humidity chamber for temperature and humidity controlled drying until the sample weight of the gel no longer changes, and the water loss is considered complete, which is the first silicon carbide ceramic green body.

[0055] 3) high temperature sintering to prepare a second silicon carbide ceramic green body: the first silicon carbide ceramic green body prepared in step 2) is placed in a muffle furnace for heating, and subjected to a binder removal and pyrolysis treatment at 750° C. in an oxidizing atmosphere, so that the C black, organic monomers and various organic additives in the first silicon carbide ceramic green body are all burned away, and the C black, organic monomers and various organic additives are all left as pores in the silicon carbide, thereby obtaining a silicon carbide porous body with a certain strength, i.e., the second silicon carbide ceramic green body, whose strength is 6 MPa; Figure 1 The following is a photo of the second silicon carbide ceramic green body prepared in this embodiment. Figure 1 It can be seen that it is a porous body including a large number of pores; Figure 2 The SEM photo of the second silicon carbide ceramic green body prepared in this embodiment is shown in FIG. Figure 2 It can be seen that the pores are more clearly visible. From the SEM image, it can be judged that the pores are generally 3 to 5 microns, which can meet the process requirements of subsequent chemical vapor deposition. Figure 3 The XRD pattern of the second silicon carbide ceramic green body prepared in this embodiment is shown in FIG. Figure 3 It can be seen that, through XRD testing and characterization, the composition of the second silicon carbide ceramic green body includes only one component, silicon carbide.

[0056] 4) Preparation of high-purity porous silicon carbide ceramics by silicon carbide film deposition: The second silicon carbide ceramic green body prepared in step 3), i.e., the silicon carbide porous body, is placed in a chemical vapor deposition (CVD) device, using monomethyltrichlorosilane as the raw material at a flow rate of 0.7 L / min; using hydrogen as a catalyst; the volume ratio of hydrogen to monomethyltrichlorosilane is 10:1; using a chemical vapor deposition process at 1200°C to deposit silicon carbide, so that a layer of high-purity SiC coating is deposited on the pore ribs and pore walls of the silicon carbide porous body. Figure 4 The SEM photo of the high-purity porous silicon carbide ceramic prepared in this embodiment is shown in FIG. Figure 4 It can be seen that a dense silicon carbide layer is formed on the pore walls of the pores, and the wall thickness at different positions can be measured to be 20 to 40 microns through SEM images.

[0057] In this embodiment, a high-purity SiC coating is coated on the pore walls and pore rib surfaces of a silicon carbide porous body containing only one component of silicon carbide particles to obtain a high-purity porous silicon carbide ceramic with a relatively high strength of 56 MPa and a purity of ≥99.9%.

[0058] Embodiment 2:

[0059] This embodiment prepares a high-purity porous silicon carbide ceramic, and the specific steps are as follows:

[0060] 1) Preparation of ceramic slurry: 25wt% anhydrous ethanol, 50wt% high-purity silicon carbide powder (purity 99.9%), 20wt% phenolic resin, and 5wt% tetramethylammonium hydroxide were weighed in percentage by mass; the above raw materials were added into a ball mill and ball milled for 18 hours to fully disperse the SiC powder to form a slurry.

[0061] 2) Preparing a first silicon carbide ceramic green body: The ceramic slurry prepared in step 1) is placed in a constant temperature and humidity chamber at 130° C. for curing and dried for 12 hours to obtain a first silicon carbide ceramic green body.

[0062] 3) high temperature sintering to prepare a second silicon carbide ceramic green body: the first silicon carbide ceramic green body prepared in step 2) is placed in a muffle furnace for heating, and subjected to a binder removal and pyrolysis treatment at 900° C. in an air atmosphere, so that the organic monomers and various organic additives in the first silicon carbide ceramic green body are burned out, and the organic monomers and various organic additives are left as pores in the silicon carbide, thereby obtaining a silicon carbide porous body with a certain strength, i.e., the second silicon carbide ceramic green body, whose strength is 8 MPa; XRD method test characterization shows that the composition of the second silicon carbide ceramic green body includes only one component, silicon carbide.

[0063] 4) Preparation of high-purity porous silicon carbide ceramics by silicon carbide thin film deposition: The second silicon carbide ceramic green body prepared in step 3), i.e., the silicon carbide porous body, is placed in a chemical vapor deposition (CVD) device, using monomethyltrichlorosilane as a raw material with a flow rate of 0.7 L / min; using hydrogen as a catalyst; the volume ratio of the hydrogen to monomethyltrichlorosilane is 10:1; and silicon carbide is deposited at 1200° C. using a chemical vapor deposition process, so that a layer of high-purity SiC coating is deposited on the pore ribs and pore walls of the silicon carbide porous body.

[0064] In this embodiment, a high-purity SiC coating is coated on the pore walls and pore rib surfaces of a silicon carbide porous body containing only one component of silicon carbide particles to obtain a high-strength high-purity porous silicon carbide ceramic with a strength of 52 MPa and a purity of ≥99.9%.

[0065] Embodiment 3:

[0066] This embodiment prepares a high-purity porous silicon carbide ceramic, and the specific steps are as follows:

[0067] 1) Preparation of ceramic slurry: 25wt% anhydrous ethanol, 45wt% high-purity silicon carbide powder (purity 99.9%), 5wt% carbon powder, 20wt% phenolic resin, 4.8wt% tetramethylammonium hydroxide and 0.2wt% polyvinylpyrrolidone as dispersant were weighed in percentage by mass; the above raw materials were added into a ball mill and ball milled for 18 hours to fully disperse the SiC powder and carbon powder to form a slurry.

[0068] 2) Preparing a first silicon carbide ceramic green body: drying the ceramic slurry prepared in step 1) in a constant temperature and humidity chamber at 80° C. for 12 hours, sieving to obtain a powder containing a phenolic resin binder, and then dry-pressing the powder to obtain a first silicon carbide ceramic green body.

[0069] 3) High-temperature sintering to prepare a second silicon carbide ceramic green body: The first silicon carbide ceramic green body prepared in step 2) is placed in a muffle furnace for heating, and subjected to a binder removal and pyrolysis treatment at 900° C. in an air atmosphere, so that the carbon powder, organic monomers and various organic additives in the first silicon carbide ceramic green body are burned away, and the carbon powder, organic monomers and various organic additives are retained as pores in the silicon carbide, thereby obtaining a silicon carbide porous body with a certain strength, i.e., the second silicon carbide ceramic green body, whose strength is 11 MPa; XRD method test characterization shows that the composition of the second silicon carbide ceramic green body includes only one component, silicon carbide.

[0070] 4) Preparation of high-purity porous silicon carbide ceramics by silicon carbide thin film deposition: The second silicon carbide ceramic green body prepared in step 3), i.e., the silicon carbide porous body, is placed in a chemical vapor deposition (CVD) device, using monomethyltrichlorosilane as a raw material with a flow rate of 0.7 L / min; using hydrogen as a catalyst; the volume ratio of the hydrogen to monomethyltrichlorosilane is 10:1; and silicon carbide is deposited at 1200° C. using a chemical vapor deposition process, so that a layer of high-purity SiC coating is deposited on the pore ribs and pore walls of the silicon carbide porous body.

[0071] In this embodiment, a high-purity SiC coating is coated on the pore walls and pore rib surfaces of a silicon carbide porous body containing only one component of silicon carbide particles to obtain a high-purity porous silicon carbide ceramic with a relatively high strength of 50 MPa and a purity of ≥99.9%.

[0072] The technical features in the claims and / or the specification of the present invention may be combined, and the combination is not limited to the combination obtained by reference in the claims. The technical solution obtained by combining the technical features in the claims and / or the specification is also within the protection scope of the present invention.

[0073] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A method for preparing high-purity porous silicon carbide ceramics, characterized in that: It includes the following steps: 1) preparing a first silicon carbide ceramic green body; the first silicon carbide ceramic green body is composed of silicon carbide ceramic particles with a purity of ≥99.9% and a pore-forming agent; 2) high-temperature sintering to obtain a second silicon carbide ceramic green body; the sintering temperature is greater than the burnout temperature of the pore-forming agent; the second silicon carbide ceramic green body contains only one component, namely silicon carbide ceramic particles; 3) depositing a silicon carbide film on the pore walls and pore rib surfaces of the second silicon carbide ceramic green body to cover the silicon carbide ceramic particles therein, thereby obtaining a high-purity porous silicon carbide ceramic; The strength of the second silicon carbide ceramic green body is 6-11Mpa; The deposition is chemical vapor deposition; The purity of the silicon carbide film is ≥99.9%; The thickness of the silicon carbide film is 20-40 microns.

2. The preparation method according to claim 1, characterized in that: The pore-forming agent includes an organic monomer and an organic auxiliary agent; or, in addition to the organic monomer and the organic auxiliary agent, the pore-forming agent also includes carbon powder and / or carbon black.

3. The preparation method according to claim 2, characterized in that: The high temperature sintering is to burn out all the organic monomers and organic additives; or, the high temperature sintering is to burn out all the organic monomers and organic additives, as well as carbon powder and / or carbon black; the temperature of the high temperature sintering is 400-800°C.

4. The preparation method according to claim 1, characterized in that: The raw material gas for the deposition is monomethyltrichlorosilane with a flow rate of 0.7 L / min; hydrogen is used as a catalyst; the volume ratio of hydrogen to monomethyltrichlorosilane is 10:1; and the deposition temperature is 1100-1300°C.

5. A high-purity porous silicon carbide ceramic, characterized in that: It includes: A silicon carbide porous body comprising only one component, silicon carbide; A silicon carbide coating layer, coating the pore wall surface or pore rib surface of the pores in the silicon carbide porous body; The thickness of the silicon carbide coating is 20 to 40 microns; The silicon carbide content in the high-purity porous silicon carbide ceramic is ≥99.9% and the strength is ≥50MPa; The high-purity porous silicon carbide ceramic is prepared according to the preparation method according to any one of claims 1 to 4.

6. Application of the high-purity porous silicon carbide ceramic according to claim 5 in the field of wafer processing, liquid crystal panel processing or flexible screen processing technology.

7. A ceramic suction cup, characterized in that: The material is the high-purity porous silicon carbide ceramic according to claim 5 with a purity of ≥99.9 and a strength of ≥50MPa.

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