Ceramic part with inner cavity in complex shape and preparation method and application thereof
By using low-melting-point organic materials to prepare the core and combining it with gel casting and high-temperature sintering, the cracking problem caused by the mismatch between the shrinkage of the core and the green body was solved, and low-cost molding of ceramic parts with complex internal cavities was achieved.
Patent Information
- Application Number
- CN202512024236.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-30
- Publication Date
- 2026-04-03
AI Technical Summary
Existing gel casting technology, when dealing with complex internal cavities, suffers from excessive internal stress due to the mismatch between the shrinkage of the core and the blank, making it difficult to remove the core smoothly. This leads to cracking of the ceramic parts and makes it impossible to effectively form complex-shaped internal cavities.
A core is prepared using a low-melting-point organic material, a ceramic blank is prepared by gel casting, the core is removed by heating at a low temperature, and then high-temperature sintering is performed to obtain a ceramic part with a complex-shaped internal cavity.
It enables low-cost molding of ceramic parts with complex internal cavities, suitable for various sizes and shapes, avoiding cracking problems caused by the mismatch between the core and the blank shrinkage, and improving the molding success rate.
Smart Images
Figure CN121777264A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of ceramic materials technology, specifically relating to a ceramic component with a complex-shaped internal cavity, its preparation method, and its application. Background Technology
[0002] Structural ceramics (such as silicon nitride, silicon carbide, boron carbide, alumina, and zirconium oxide) have been widely used in aerospace, electronics, biomedicine, and high-end equipment manufacturing due to their superior properties, including high strength, high hardness, wear resistance, corrosion resistance, and high temperature resistance. With technological advancements, increasingly higher demands are being placed on the shape complexity, dimensional accuracy, and performance of these ceramic components. For example, structural parts with complex internal flow channels, thin walls, irregular curved surfaces, or large-sized integrated structures are required. Currently, near-net-shape forming technologies for complex-shaped ceramic components mainly include injection molding, gel casting, and 3D printing. Among these, gel casting has attracted significant attention due to its relatively simple process equipment, ability to produce large-sized and complex-shaped green bodies, good green body uniformity, and low organic content. Gel casting technology involves injecting a low-viscosity ceramic slurry into a mold, where in-situ polymerization of organic monomers forms a three-dimensional network gel, firmly encapsulating and solidifying the ceramic particles to obtain a high-density, high-strength green body. While gel casting technology can achieve near-net-shape molding of complex shapes, its inherent limitations become apparent when dealing with complex internal cavities: the volume shrinkage of the gel preform during the drying stage generates a strong clamping force on the internal core, making it impossible to remove the core smoothly. The mismatch between the shrinkage of the core and the preform creates enormous internal stress, ultimately leading to cracking of the green preform, which has become a key bottleneck restricting the application of this technology. Some parts have complex internal cavity shapes that are difficult to form using traditional molding methods and cannot be machined. Summary of the Invention
[0003] To address the shortcomings of the existing technology, the primary objective of this invention is to provide a method for preparing ceramic components with complex-shaped internal cavities. This method employs gel casting, using a low-melting-point organic material to prepare the core. After the ceramic green body is stably formed, the core material is removed by melting it at a low temperature, resulting in a ceramic green body with complex-shaped internal cavities. This green body is then sintered in a high-temperature furnace to obtain a dense ceramic component. This method is suitable for preparing various ceramic components with complex-shaped internal cavities.
[0004] Another object of the present invention is to provide a ceramic component with a complex-shaped internal cavity obtained by the above method.
[0005] Another object of the present invention is to provide the application of the above-mentioned ceramic component with a complex-shaped internal cavity.
[0006] The objective of this invention is achieved through the following technical solution: A method for fabricating a ceramic component with a complex-shaped internal cavity includes the following specific steps: S1. Prepare a mold according to the shape of the ceramic part, and install a core made of low-melting-point organic material into the mold to obtain a mold with an internal core; S2. Ceramic powder, gel monomer, crosslinking agent, pH adjuster, dispersant, catalyst and solvent are mixed and ball-milled to obtain ceramic slurry; S3. Degas the ceramic slurry in a vacuum environment for 5-15 minutes, then add the initiator and stir thoroughly. Pour the mixture into a mold with an internal core and let it stand to gel, thus obtaining a ceramic gel green body. S4. Place the ceramic gel green body in an environment with humidity of 60~100%RH, heat it at 45~95℃ to melt and remove the core, and after drying, degelatinate it at 600~900℃ to obtain the ceramic green body; S5. The ceramic blank is sintered in air or under a protective atmosphere at 1200~2200℃ to obtain a ceramic part with a complex internal cavity.
[0007] Preferably, the low-melting-point organic compound in step S1 is one or more of carboxylic acids, alcohols, esters, and hydrocarbons, which is solid at room temperature <35°C and melts at 45~95°C; the core is prepared by casting, injection molding, 3D printing, or machining.
[0008] More preferably, the carboxylic acid is lauric acid or stearic acid; the alcohol is cetyl alcohol, stearyl alcohol or polyethylene glycol; the ester is phenyl salicylate, rosin or butter; and the hydrocarbon is paraffin.
[0009] Preferably, in step S2, the gel monomer is one or more of acrylamide, methacrylamide, hydroxymethylacrylamide, or hydroxyethyl acrylate; the ceramic powder is silicon nitride, alumina, zirconium oxide, silicon carbide, or boron carbide; the crosslinking agent is one or more of N,N'-methylenebisacrylamide, polyethylene glycol dimethacrylate, or polyethylene glycol diacrylate; the pH adjuster is one or more of ammonia, triethanolamine, or tetramethylammonium hydroxide; the dispersant is one or more of ammonium polyacrylate, polyvinylpyrrolidone, or PEG; the catalyst is one or more of N,N-dimethyl-p-toluidine, N,N,N',N'-tetramethylethylenediamine, or ferrous sulfate; and the solvent is deionized water and / or anhydrous ethanol.
[0010] Preferably, in step S2, the mass ratio of the gel monomer to the crosslinking agent is (1~5):(0.2~0.3); the mass ratio of the catalyst to the crosslinking agent is (0.02~0.1):(0.8~1.2); the amount of gel monomer added is 0.5~15wt% of the ceramic powder mass; and the mass ratio of the pH adjuster, dispersant, catalyst and solvent is (1~4):(1~4):(0.02~1):(75~95).
[0011] Preferably, the initiator in step S3 is one or more of ammonium persulfate, sodium bisulfite, potassium bisulfite, or potassium persulfate, and the amount of the initiator added is 0.01~2 wt% of the ceramic powder mass.
[0012] Preferably, the degassing time in step S3 is 5-15 minutes; the heating and melting in step S4 is performed using a water bath, oil bath, or electric heating mantle.
[0013] Preferably, when the ceramic green body in step S5 is an oxide, it is sintered at 1200~1750℃ in an air environment; when the ceramic green body is a nitride, it is sintered at 1600~2000℃ in a nitrogen environment; when the ceramic green body is a carbide, it is sintered at 1600~2200℃ in an argon environment.
[0014] A ceramic component with a complex-shaped internal cavity is obtained by the method described above.
[0015] The ceramic components with complex-shaped cavities are used in the chemical, energy, or electronic fields.
[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses low-melting-point organic materials to prepare the core, and uses gel casting to prepare ceramic parts with complex-shaped cavities.
[0017] 2. The present invention uses gel casting molding, which has a low cost, is applicable to various ceramic powders, and can form ceramic parts of various sizes with complex internal cavities. Attached Figure Description
[0018] Figure 1 This is a top view and a schematic diagram of the structure of the ceramic component with an internal cavity structure in Example 1; Figure 2 This is a top view and a schematic diagram of the cetyl alcohol core of Example 1. Figure 3 This is a top view and a schematic diagram of the structure of the ceramic component with an internal cavity structure in Example 2; Figure 4 This is a top view and a schematic diagram of the structure of the stearic acid core with inner cavity in Example 2; Figure 5 This is a top view and a schematic diagram of the structure of the ceramic component with an internal cavity structure in Example 3; Figure 6 The image shows a top view and a schematic diagram of the structure of the inner cavity paraffin core of Example 3. Detailed Implementation
[0019] The present invention will be further described in detail below with reference to embodiments, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.
[0020] Example 1 1. Prepare a mold according to the shape of the ceramic part, and prepare the core by melting and casting. The core material is cetyl alcohol (whose melting temperature is about 50°C). The remaining mold material is 304 stainless steel. Install the core prepared by low melting point organic material into the mold to obtain a mold with built-in core. 2. Mix 200g of Si3N4 ceramic powder, 5g of methacrylamide, 1g of polyethylene glycol dimethacrylic acid, 2g of ammonia, 1g of ammonium polyacrylate, 0.1g of N,N-dimethyl-p-toluidine and 93.75g of deionized water and ball mill for 2 hours. The mass ratio of ball to powder is 2:1 to obtain ceramic slurry. 3. Degas the ceramic slurry under a vacuum of -0.1MPa for 5 minutes, add 0.05g of ammonium persulfate and stir thoroughly. Pour the mixture into a mold with an internal core and let it stand to gel for 3 hours to obtain a ceramic gel preform. 4. The ceramic gel green body is heated in a 50°C water bath at 60%RH to remove the core material cetyl alcohol. Then, it is placed in a degumming furnace and heated to 600°C for slow degumming to obtain the ceramic green body. 5. The ceramic blank is placed in a crucible in a high-temperature furnace and sintered at 1800℃ under a nitrogen atmosphere to obtain a ceramic part with a complex internal cavity, the structure of which is as follows: Figure 1 As shown, the inner cavity is as follows Figure 2 As shown, the sample is then machined according to its dimensions.
[0021] Example 2 1. Prepare a mold according to the shape of the ceramic part, and prepare the core by injection molding. The core material is stearic acid (decomposition temperature is about 70℃), and the remaining mold material is acrylic. Install the core made of low melting point organic material into the mold to obtain a mold with built-in core. 2. Mix 200g of Al2O3 ceramic powder, 12g of methacrylamide, 1g of N,N'-methylenebisacrylamide, 1g of ammonia, 2g of ammonium polyacrylate, 0.5g of N,N,N',N'-tetramethylethylenediamine and 75.19g of deionized water and ball mill for 2 hours. The ball-to-powder mass ratio is 2:1 to obtain a ceramic slurry. 3. Degas the ceramic slurry under a vacuum of -0.08MPa for 10 minutes, add 0.08g of potassium persulfate and stir thoroughly. Pour the mixture into a mold with an internal core and let it stand to gel for 4 hours to obtain a ceramic gel green body. 4. Low-temperature heating to remove the core: The ceramic gel green body is heated in an 80%RH environment and heated in an oil bath at 70℃ to remove the stearic acid core material. Then, it is placed in a degumming furnace and heated to 800℃ for slow degumming to obtain the ceramic green body. 5. The ceramic blank is placed in a crucible in a high-temperature furnace and sintered at 1700℃ in air to obtain a ceramic part with a complex internal cavity, the structure of which is as follows: Figure 3 As shown, the inner cavity is as follows Figure 4 As shown, the sample is then machined according to its dimensions.
[0022] Example 3 1. Prepare a mold according to the shape of the ceramic part, and prepare the core using 3D printing. The core material is paraffin wax (decomposition temperature below 90℃), and the remaining mold material is 6063 aluminum alloy. Install the core made of low melting point organic material into the mold to obtain a mold with an internal core. 2. Mix 200g of SiC ceramic powder, 20g of hydroxymethylacrylamide, 1g of N,N'-methylenebisacrylamide, 4g of tetramethylammonium hydroxide, 4g of ammonium polyacrylate, 0.2g of ferrous sulfate and 76.39g of deionized water and ball mill for 2 hours. The ball-to-powder mass ratio is 2:1 to obtain ceramic slurry. 3. Degas the ceramic slurry under a vacuum of -0.1MPa for 15 minutes, add 0.1g of potassium persulfate and stir thoroughly. Pour the mixture into a mold with an internal core and let it stand to gel for 3 hours to obtain a ceramic gel preform. 4. The ceramic gel green body is heated at 90°C in a 100%RH environment to remove the core material paraffin. Then, it is placed in a degumming furnace and heated to 900°C to slowly degumme the material, thus obtaining the ceramic green body. 5. The ceramic blank is placed in a crucible in a high-temperature furnace and sintered at 2000℃ under an argon atmosphere to obtain a ceramic part with a complex internal cavity, the structure of which is as follows: Figure 5 As shown, the inner cavity is as follows Figure 6 As shown, the sample is then machined according to its dimensions.
[0023] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.
Claims
1. A method for preparing a ceramic component with a complex-shaped internal cavity, characterized in that, The specific steps include the following: S1. Prepare a mold according to the shape of the ceramic part, and install a core made of low-melting-point organic material into the mold to obtain a mold with an internal core; S2. Ceramic powder, gel monomer, crosslinking agent, pH adjuster, dispersant, catalyst and solvent are mixed and ball-milled to obtain ceramic slurry; S3. Degas the ceramic slurry under vacuum, add an initiator and stir thoroughly, pour it into a mold with an internal core and let it stand to gel, thus obtaining a ceramic gel preform; S4. Place the ceramic gel green body in an environment with humidity of 60~100%RH, heat it at 45~95℃ to melt and remove the core, and after drying, degelatinate it at 600~900℃ to obtain the ceramic green body; S5. The ceramic blank is sintered in air or under a protective atmosphere at 1200~2200℃ to obtain a ceramic part with a complex internal cavity.
2. The method for preparing a ceramic component with a complex-shaped internal cavity according to claim 1, characterized in that, The low-melting-point organic compound mentioned in step S1 is one or more of carboxylic acids, alcohols, esters, and hydrocarbons, which is solid at room temperature <35℃ and melts at 45~95℃; the core prepared is produced by melt casting, injection molding, 3D printing, or machining.
3. The method for preparing a ceramic component with a complex-shaped internal cavity according to claim 2, characterized in that, The carboxylic acid is lauric acid or stearic acid; the alcohol is cetyl alcohol, stearyl alcohol or polyethylene glycol; the ester is phenyl salicylate, rosin or butter; and the hydrocarbon is paraffin.
4. The method for preparing a ceramic component with a complex-shaped internal cavity according to claim 1, characterized in that, In step S2, the gel monomer is one or more of acrylamide, methacrylamide, hydroxymethylacrylamide, or hydroxyethyl acrylate; the ceramic powder is silicon nitride, alumina, zirconium oxide, silicon carbide, or boron carbide; the crosslinking agent is one or more of N,N'-methylenebisacrylamide, polyethylene glycol dimethacrylate, or polyethylene glycol diacrylate; the pH adjuster is one or more of ammonia, triethanolamine, or tetramethylammonium hydroxide; the dispersant is one or more of ammonium polyacrylate, polyvinylpyrrolidone, or PEG; the catalyst is one or more of N,N-dimethyl-p-toluidine, N,N,N',N'-tetramethylethylenediamine, or ferrous sulfate; and the solvent is deionized water and / or anhydrous ethanol.
5. The method for preparing a ceramic component with a complex-shaped internal cavity according to claim 1, characterized in that, In step S2, the mass ratio of gel monomer to crosslinking agent is (1~5):(0.2~0.3); the mass ratio of catalyst to crosslinking agent is (0.02~0.1):(0.8~1.2); the amount of gel monomer added is 0.5~15wt% of the ceramic powder mass; the mass ratio of pH adjuster, dispersant, catalyst and solvent is (1~4):(1~4):(0.02~1):(75~95).
6. The method for preparing a ceramic component with a complex-shaped internal cavity according to claim 1, characterized in that, The initiator mentioned in step S3 is one or more of ammonium persulfate, sodium bisulfite, potassium bisulfite, and potassium persulfate, and the amount of the initiator added is 0.01~2wt% of the ceramic powder mass.
7. The method for preparing a ceramic component with a complex-shaped internal cavity according to claim 1, characterized in that, The degassing time in step S3 is 5-15 minutes; the heating and melting in step S4 is performed using a water bath, oil bath, or electric heating mantle.
8. The method for preparing a ceramic component with a complex-shaped internal cavity according to claim 1, characterized in that, When the ceramic green body in step S5 is an oxide, it is sintered at 1200~1750℃ in an air environment; when the ceramic green body is a nitride, it is sintered at 1600~2000℃ in a nitrogen environment; when the ceramic green body is a carbide, it is sintered at 1600~2200℃ in an argon environment.
9. A ceramic component with a complex-shaped internal cavity, characterized in that, The ceramic component is prepared by the method described in any one of claims 1-8.
10. The application of the ceramic component with a complex-shaped internal cavity according to claim 9 in the chemical, energy or electronic fields.