3D printing pure silicon carbide porous ceramic and preparation method thereof

Abstract

The invention discloses a 3D printing pure silicon carbide porous ceramic and a preparation method thereof, and belongs to the technical field of porous ceramics. According to the method disclosed by the invention, the silicon carbide mixed powder material, the photosensitive resin monomer, the additive, the photoinitiator, the dispersing agent and the thickening agent are used as raw materials, so that the finally prepared silicon carbide porous ceramic consists of a pure silicon carbide phase, and the bonding firmness between crystal grains can be effectively improved; therefore, the mechanical strength of the porous ceramic can be effectively improved, no sintering aid is introduced, no oxide is introduced in the process, the preparation of the pure silicon carbide porous ceramic can be realized, and the thermal conductivity, elastic modulus and high-temperature usability of the ceramic material can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of porous ceramics, and in particular relates to a 3D printed pure silicon carbide porous ceramic and a preparation method thereof. Background Art

[0002] There is a three-dimensional network skeleton structure inside silicon carbide porous ceramics, so that a large number of pores are evenly distributed inside the ceramics, with a high comparative area. These pores are mainly composed of through holes and closed holes, giving it unique properties. High porosity not only increases the specific surface area of ​​the material, but also improves its permeability and filtration efficiency; silicon carbide porous ceramics are made of silicon carbide particles as ceramic aggregates, and other ceramic adhesives are added and sintered under high temperature conditions. During the sintering process, the ceramic binder melts at high temperature and solidifies during the cooling process, tightly bonding the silicon carbide particles together, thereby giving the material a high flexural strength; silicon carbide is a typical covalent compound, and there is a strong covalent bond between C and Si, so it is difficult to react with acids and alkalis. Under high temperature conditions, silicon carbide is also difficult to decompose or melt, which makes silicon carbide porous ceramics resistant to high temperatures, strong acid and alkali corrosion, and has good chemical stability; because silicon carbide porous ceramics have a high porosity, they are mainly used in the field of filtration. The large number of through holes inside allow the filtered solution to fully contact the ceramic material, thereby improving the filtration efficiency. In addition, after a period of use, its filtering capacity can be restored by simple flushing, which has good reproducibility. Based on the above advantages, silicon carbide porous ceramics are ideal materials for use in the fields of pillars, biology, catalysis, filtration and metal matrix composite material preparation.

[0003] At present, the most commonly used methods for preparing silicon carbide porous ceramics are mainly pore-forming agent sintering and organic foam impregnation. These methods will add more or less sintering aids during the sintering process, introduce oxides and other easily fusible substances, and cannot prepare pure silicon carbide porous ceramics. It is easy to affect the thermal conductivity, elastic modulus and high-temperature performance of the final material. Summary of the invention

[0004] The purpose of the present invention is to provide a 3D printed pure silicon carbide porous ceramic and a preparation method thereof, so as to solve the technical problem that the existing preparation methods are difficult to achieve the preparation of pure silicon carbide porous ceramics.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention discloses a method for preparing 3D printed pure silicon carbide porous ceramics, comprising the following steps: The photosensitive resin monomer, additives and photoinitiator are mixed and stirred to obtain a premixed liquid, and then the silicon carbide mixed powder material, dispersant and thickener are added to the premixed liquid and stirred to obtain a ceramic paste; The ceramic paste is subjected to light-curing 3D printing to obtain a ceramic blank; After degreasing, sintering and decarbonizing the ceramic blank in sequence, 3D printed pure silicon carbide porous ceramics are obtained.

[0006] Furthermore, in terms of mass percentage, the silicon carbide mixed powder material is obtained by mixing 50%-90% silicon carbide, 10%-25% silicon dioxide and 0%-25% cured phenolic resin microspheres.

[0007] Further, the particle size of the silicon carbide is one or more of 2-3um, 15-20um and 50-57um; The particle size of the silicon dioxide is 0.5-30um; the particle size of the cured phenolic resin microspheres is 15-30um.

[0008] Furthermore, the mass ratio of the silicon carbide mixed powder material to the premixed liquid is (2-7): (1-3); the content of the additive is 20 wt.%-30 wt.% of the total amount of the photosensitive resin; and the amount of the photoinitiator added is 2 wt.%-8 wt.% of the total amount of the photosensitive resin monomer.

[0009] Furthermore, the amount of the dispersant added is 2wt.%-3wt.% of the total amount of the silicon carbide mixed powder material; The thickener is added in an amount of 2 wt.%-4 wt.% of the total amount of the photosensitive resin monomer.

[0010] Further, the photosensitive resin monomer is one or more of 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, dipentaerythritol hexaacrylate and 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate; The additive is one or more of 4,4′-isopropyldiphenol, fluorenyl acrylic acid, fluorenyl acrylic acid composite glue, and (3-glycidyl propoxy) trimethoxy silane; The photoinitiator is one or more of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, 2-isopropylthioxanthone, ethyl 4-dimethylaminobenzoate and 4-isobutylphenyl-4'-methylphenyliodine hexafluorophosphate; The dispersant is one or more of KOS110, Solsperse 85000 and 9065; The thickener is one or more of carbomer, stearic acid and BYK-405.

[0011] Furthermore, the method of stirring the added silicon carbide mixed powder material is ball milling or homogenization; the speed of the ball milling is 300-350 r / min, and the time is 20-26h; the speed of the homogenization is 1000-2000 r / min, and the time is 1-3min.

[0012] Furthermore, the parameters of the light-curing 3D printing are: An ultraviolet laser with a wavelength of 355nm is used, with a power of 500mW-700mW, a scanning speed of 1200mm / s-2500mm / s, a scanning offset of 0.005-0.1mm, and a single-layer lift of 25um-70um.

[0013] Furthermore, the process parameters of the degreasing are: Under an inert atmosphere, heat from room temperature to 150-450°C at a heating rate of 0.25-5°C / min, keep warm for 0.5h-4h, continue to heat to 500-900°C at a heating rate of 2-5°C / min, keep warm for 0-2h, then heat to 1200-1300°C at a heating rate of 3-5°C / min, keep warm for 1-2h, and cool to room temperature; The process parameters of the sintering are: In an inert atmosphere, heat from room temperature to 1600-2200°C at a heating rate of 2-5°C / min, keep warm for 4-5h, and cool to room temperature; The process parameters of the carbon removal are: In an air atmosphere, heat from room temperature to 500-600°C at a heating rate of 2-5°C / min, keep warm for 2-3h, and cool to room temperature.

[0014] The invention also discloses 3D printed pure silicon carbide porous ceramics prepared by the preparation method.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a preparation method of 3D printed pure silicon carbide porous ceramics, which uses silicon carbide mixed powder material, photosensitive resin monomer, additives, photoinitiator, dispersant and thickener as raw materials, wherein the photosensitive resin monomer is cured to form a silicon carbide ceramic blank, which can be cracked and converted into amorphous carbon in the subsequent degreasing process, and the generated amorphous carbon can play a bonding role on silicon carbide particles, so that the ceramic blank has a certain strength, and at the same time, the amorphous carbon cracked by the resin system formed by the photosensitive resin monomer during the sintering process will react with silicon dioxide in the powder to generate carbonized The generated silicon carbide replaces the role of amorphous carbon in the high temperature stage, so that the silicon carbide particles are bonded together with a certain strength. This process does not generate any by-products, which not only makes the final silicon carbide porous ceramics composed of pure silicon carbide phase, but also can effectively improve the firmness of the bonding between the grains, thereby effectively improving the mechanical strength of the porous ceramics; the present invention adopts the light-curing 3D printing method, does not introduce sintering aids, does not introduce oxides in the process, can realize the preparation of pure silicon carbide porous ceramics, and improves the thermal conductivity, elastic modulus and high-temperature performance of ceramic materials.

[0016] Furthermore, the method of the present invention combines the advantages of additive manufacturing design to achieve customized preparation of multi-level porous materials, greatly expanding the application range of porous ceramic materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the XRD pattern of the porous silicon carbide ceramic of the present invention; Figure 2 This is a SEM image of a cross section of the porous silicon carbide ceramic of the present invention; Figure 3 is the porosity of the porous silicon carbide ceramic of the present invention. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0019] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0020] In this article, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0021] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0022] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0023] The present invention provides a method for preparing 3D printed pure silicon carbide porous ceramics, comprising the following steps: Step 1: Weigh the powder materials according to the following formula to obtain a silicon carbide mixed powder material: by mass percentage, weigh 50%-90% silicon carbide, 10%-25% silicon dioxide, and 0%-25% cured phenolic resin microspheres; Step 2: Mix and stir the photosensitive resin monomer, additives and photoinitiator to obtain a premixed liquid, then add the silicon carbide mixed powder material, dispersant and thickener to the premixed liquid, and mill for 20-26 hours at a speed of 300-350 r / min in a planetary ball mill or homogenize for 1-3 minutes at a speed of 1000-2000 r / min in a homogenizer to obtain a ceramic paste; Step 3: Place the ceramic paste into a ceramic 3D printing device for light-curing 3D printing to obtain a ceramic blank; Step 4: After degreasing, sintering and decarbonizing the ceramic blank in sequence, 3D printed pure silicon carbide porous ceramics are obtained.

[0024] Preferably, silicon dioxide can be added in the form of solid microspheres or hollow microspheres, or introduced through surface oxidation of silicon carbide powder or conversion of tetraethyl orthosilicate, with a particle size of 0.5-30 um; the particle size of phenolic resin microspheres is 15-30 um.

[0025] Preferably, the mass ratio of the silicon carbide mixed powder material to the premixed liquid is (2-7): (1-3); the content of the additive is 20 wt.%-30wt.% of the total amount of the photosensitive resin monomer; the amount of the photoinitiator added is 2wt.%-8wt.% of the total amount of the photosensitive resin monomer; the amount of the dispersant added is 2wt.%-3wt.% of the total amount of the silicon carbide mixed powder material; and the amount of the thickener added is 2 wt.%-4wt.% of the total amount of the photosensitive resin monomer.

[0026] Preferably, the photosensitive resin monomer is one or more of 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, dipentaerythritol hexaacrylate and 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate; the additive is one or more of 4,4′-isopropyldiphenol, fluorenyl acrylic acid and fluorenyl acrylic acid composite glue, (3-glycidyl propoxy) trimethoxysilane; the photoinitiator is one or more of (2,4,6-trimethylbenzoyl) diphenylphosphine oxide, 2-isopropylthioxanthone, ethyl 4-dimethylaminobenzoate and 4-isobutylphenyl-4′-methylphenyl iodine hexafluorophosphate; the dispersant is one or more of KOS110, Solsperse 85000 and 9065; the thickener is one or more of carbomer, stearic acid and BYK-405.

[0027] Preferably, the parameters of photocuring 3D printing are: using ultraviolet laser with a wavelength of 355nm, under the conditions of power 600mW-700mW, scanning speed 1200mm / s-2500mm / s, scanning offset 0.005-0.1mm, and single layer lift 25um-70um.

[0028] Preferably, the printed silicon carbide blank is cleaned and dried and then placed in a tubular furnace for inert atmosphere degreasing, and the temperature is increased from room temperature to 150°C-450°C at a heating rate of 0.25-5°C / min, and kept warm for 0.5h-4h, and then the temperature is increased to 500-900°C at a heating rate of 2-5°C / min, and kept warm for 0-2h, and then the temperature is increased to 1200-1300°C at a heating rate of 3-5°C / min, and kept warm for 1-2h, and then cooled to room temperature to obtain the degreased silicon carbide blank.

[0029] Preferably, the degreased silicon carbide blank is heated from room temperature to 1600-2200° C. at a heating rate of 2-5° C. / min in an argon atmosphere, kept at this temperature for 4-5 hours, and cooled to room temperature to allow the silicon dioxide to undergo a carbothermal reduction reaction with the network carbon skeleton.

[0030] Preferably, the sintered silicon carbide is heated from room temperature to 500-600°C at a heating rate of 2-5°C / min in an air atmosphere, kept warm for 2-3 hours, cooled to room temperature, and excess carbon in the sintered body is removed to obtain a pure silicon carbide porous ceramic material.

[0031] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0032] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0033] Example 1 A method for preparing 3D printed pure silicon carbide porous ceramics comprises the following steps: Step 1: Evenly mix 20um silicon carbide powder with ethanol and deionized water, and slowly drip tetraethyl orthosilicate and ammonia water in sequence while stirring, so that tetraethyl orthosilicate undergoes hydrolysis reaction with deionized water in an alkaline environment to convert into silicon dioxide microspheres with a particle size of about 0.5um. After the reaction is completed, a mixed powder of silicon carbide and silicon dioxide is obtained by centrifugal filtration, drying, and sieving. The ratio of tetraethyl orthosilicate and deionized water is adjusted so that the mass fraction of silicon carbide in the mixed powder is 90% and the mass fraction of silicon dioxide is 10%; Step 2: 10 wt.% of 1,6-hexanediol diacrylate, 7.5 wt.% of tripropylene glycol diacrylate, 25 wt.% of trimethylolpropane triacrylate, 20 wt.% of dipentaerythritol hexaacrylate and 37.5 wt.% of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate are mixed to obtain a photosensitive resin monomer; Step 3: respectively adding 12.5 wt.% of the total amount of the photosensitive resin monomer of the additive 4,4′-isopropyldiphenol and 12.5 wt.% of the total amount of the photosensitive resin monomer of the additive fluorenyl acrylic acid and the composite glue of fluorenyl acrylic acid to the photosensitive resin monomer in step 2, and mixing them thoroughly to obtain a mixed resin; Step 4: respectively adding 2 wt.% of the total amount of photosensitive resin monomers of a photoinitiator (2,4,6-trimethylbenzoyl) diphenylphosphine oxide, 2 wt.% of the total amount of photosensitive resin monomers of a photoinitiator 2-isopropylthioxanthone, 2 wt.% of the total amount of photosensitive resin monomers of a photoinitiator 4-isobutylphenyl-4'-methylphenyliodine hexafluorophosphate, and 1 wt.% of the total amount of photosensitive resin monomers of a co-initiator 4-dimethylaminobenzoic acid ethyl ester to the mixed resin in step 3 to completely dissolve them to obtain a premixed solution; Step 5: The silicon carbide mixed powder material in step 1 and the premixed liquid in step 4 are mixed in a mass ratio of 7:3, and 3 wt.% of the total amount of the silicon carbide mixed powder material and 2 wt.% of the total amount of the photosensitive resin monomer, the thickener BYK-405, are added, and the mixture is homogenized at a speed of 2000 r / min for 2 minutes to obtain a ceramic paste; Step 6: Place the ceramic paste in the silo of the ceramic printer, import the model into the printer computer, level the printer and then print, use a 355nm wavelength ultraviolet laser, where the laser power is set to 540mW, the scanning speed is set to 2500mm / s, the scanning interval is set to 0.08mm, and the layer thickness is set to 25μm. After printing, a ceramic blank is obtained; Step 7: After cleaning and drying the ceramic blank, place it in a tubular furnace for inert atmosphere degreasing, heat it to 150°C at 5°C / min, heat it to 280°C at a heating rate of 2°C / min, keep it warm for 2h, heat it to 350°C at a heating rate of 2°C / min, keep it warm for 2h, heat it to 500°C at a heating rate of 1°C / min, keep it warm for 4h, heat it to 900°C at a heating rate of 5°C / min, keep it warm for 1h, and then cool it to room temperature with the furnace to obtain carbon skeleton supported silicon carbide porous ceramics; Step 8: Place the carbon skeleton supported silicon carbide porous ceramics into an atmosphere sintering furnace for inert atmosphere sintering, heat up to 1300°C at 5°C / min, then heat up to 1600°C at 10°C / min, keep warm for 3 hours, and then cool to room temperature with the furnace to complete the carbon thermal reduction reaction of the carbon skeleton and silicon dioxide, and obtain a mesh silicon carbide supported silicon carbide porous ceramics; Step 9: Raise the temperature of the silicon carbide porous ceramic supported by the mesh silicon carbide to 600°C at 3°C / min and keep it warm for 3 hours to remove excess carbon in the silicon carbide porous ceramic, and finally obtain 3D printed pure silicon carbide porous ceramic.

[0034] Example 2 A method for preparing 3D printed pure silicon carbide porous ceramics comprises the following steps: Step 1: Weigh 35% of 50um silicon carbide, 24% of 20um silicon carbide, 24% of 3um silicon carbide, and 20% of 5um silicon dioxide in terms of mass percentage; Step 2: Fully mix 50 wt.% of 1,6-hexanediol diacrylate and 50 wt.% of trimethylolpropane triacrylate to obtain a photosensitive resin monomer; Step 3: Add 2 wt.% of the photoinitiator (2,4,6-trimethylbenzoyl) diphenylphosphine oxide to the photosensitive resin monomer in step 2 to completely dissolve the photosensitive resin monomer to obtain a premixed solution; Step 4: The silicon carbide mixed powder material in step 1 and the premixed liquid in step 3 are mixed in a mass ratio of 4:1, and 2 wt.% of the total amount of the silicon carbide mixed powder and 2 wt.% of the thickener Carbomer are added, and the mixture is ball-milled at a speed of 300 r / min for 26 hours to obtain a ceramic paste; Step 5: Place the ceramic paste in the silo of the ceramic printer, import the model into the printer computer, level the printer and then print, use a 355nm wavelength ultraviolet laser, where the laser power is set to 660mW, the scanning speed is set to 1200mm / s, the scanning spacing is set to 0.005mm, and the layer thickness is set to 70μm. After printing, a ceramic blank is obtained; Step 6: After cleaning and drying the ceramic blank, place it in a tubular furnace for inert atmosphere degreasing, heat it to 450°C at a rate of 1°C / min, keep it warm for 0.5h, then heat it to 500°C at a rate of 1°C / min, heat it to 1300°C at a rate of 5°C / min, keep it warm for 1h, and then cool it to room temperature with the furnace to obtain silicon carbide porous ceramics supported by a carbon skeleton; Step 7: Place the carbon skeleton supported silicon carbide porous ceramics in an atmosphere sintering furnace for inert atmosphere sintering, heat up to 1300°C at 5°C / min, then heat up to 1600°C at 10°C / min, keep warm for 3 hours, and then cool to room temperature with the furnace to complete the carbon thermal reduction reaction of the carbon skeleton and silicon dioxide, and obtain a mesh silicon carbide supported silicon carbide porous ceramics; Step 8: Raise the temperature of the silicon carbide porous ceramic supported by the mesh silicon carbide to 600°C at 3°C / min and keep it warm for 3 hours to remove excess carbon in the silicon carbide porous ceramic, and finally obtain 3D printed pure silicon carbide porous ceramic.

[0035] Example 3 A method for preparing 3D printed pure silicon carbide porous ceramics comprises the following steps: Step 1: Weigh 28% of 50um silicon carbide, 21% of 20um silicon carbide, 21% of 3um silicon carbide, 20% of 5um silicon dioxide and 10% of 35um phenolic resin microspheres in terms of mass percentage; Step 2: fully mixing 75 wt.% of 1,6-hexanediol diacrylate and 25 wt.% of trimethylolpropane triacrylate to obtain a photosensitive resin monomer; Step 3: Add 2 wt.% of the photoinitiator (2,4,6-trimethylbenzoyl) diphenylphosphine oxide to the photosensitive resin monomer in step 2 to completely dissolve the photosensitive resin monomer to obtain a premixed solution; Step 4: The silicon carbide mixed powder material in step 1 and the premixed liquid in step 3 are mixed in a mass ratio of 4:1, and 2 wt.% of the total amount of the silicon carbide mixed powder material is added as a dispersant KOS110 and 2 wt.% of the total amount of the photosensitive resin monomer as a thickener Carbomer. The mixture is ball-milled at a speed of 300 r / min for 24 hours to obtain a ceramic paste; Step 5: Place the ceramic paste in the silo of the ceramic printer, import the model into the printer computer, level the printer and then print, use a 355nm wavelength ultraviolet laser, where the laser power is set to 600mW, the scanning speed is set to 1200mm / s, the scanning spacing is set to 0.007mm, and the layer thickness is set to 75μm. After printing, a ceramic blank is obtained; Step 6: After cleaning and drying the ceramic blank, place it in a tubular furnace for inert atmosphere degreasing, heat it to 450°C at a rate of 1°C / min, keep it warm for 0.5h, heat it to 500°C at a rate of 1°C / min, heat it to 800°C at a rate of 5°C / min, keep it warm for 1h, heat it to 1300°C at a rate of 5°C / min, keep it warm for 1h, and cool it to room temperature with the furnace to obtain silicon carbide porous ceramics supported by a carbon skeleton; Step 7: Place the carbon skeleton supported silicon carbide porous ceramics in an atmosphere sintering furnace for inert atmosphere sintering, heat up to 1300°C at 5°C / min, then heat up to 1600°C at 10°C / min, keep warm for 3 hours, and then cool to room temperature with the furnace to complete the carbon thermal reduction reaction of the carbon skeleton and silicon dioxide, and obtain a mesh silicon carbide supported silicon carbide porous ceramics; Step 8: Raise the temperature of the silicon carbide porous ceramic supported by the mesh silicon carbide to 600°C at 3°C / min and keep it warm for 3 hours to remove excess carbon in the silicon carbide porous ceramic, and finally obtain 3D printed pure silicon carbide porous ceramic.

[0036] Example 4 A method for preparing 3D printed pure silicon carbide porous ceramics comprises the following steps: Step 1: Weigh 40% of 50um silicon carbide, 30% of 20um silicon carbide and 30% of 3um silicon carbide by mass percentage; Step 2: fully mixing 75 wt.% of 1,6-hexanediol diacrylate and 25 wt.% of trimethylolpropane triacrylate to obtain a photosensitive resin monomer; Step 3: Add 2 wt.% of the photoinitiator (2,4,6-trimethylbenzoyl) diphenylphosphine oxide to the photosensitive resin monomer in step 2 to completely dissolve the photosensitive resin monomer to obtain a premixed solution; Step 4: The silicon carbide mixed powder material in step 1 and the premixed liquid in step 3 are mixed in a mass ratio of 7:3, and 2 wt.% of the total amount of the silicon carbide mixed powder material is added as a dispersant KOS110 and 2 wt.% of the total amount of the photosensitive resin monomer as a thickener Carbomer. The mixture is ball-milled at a speed of 300 r / min for 24 h to obtain a ceramic paste; Step 5: Add 30um hollow silica microspheres to the ceramic paste in step 4, mix well, and then homogenize on a homogenizer at 1000r / min for 2min to obtain a final ceramic paste, wherein the mass ratio of the hollow silica microspheres to the silicon carbide mixed powder material is 1:9; Step 6: Place the ceramic paste obtained in step 5 into the silo of the ceramic printer, import the model into the printer computer, level the printer and then print, use a 355nm wavelength ultraviolet laser, wherein the laser power is set to 660mW, the scanning speed is set to 1200mm / s, the scanning spacing is set to 0.005mm, and the layer thickness is set to 70μm, and a ceramic blank is obtained after printing; Step 7: After cleaning and drying the ceramic blank, place it in a tubular furnace for inert atmosphere degreasing, heat it to 450°C at a rate of 1°C / min, keep it warm for 0.5h, heat it to 500°C at a rate of 1°C / min, heat it to 1300°C at a rate of 5°C / min, keep it warm for 1h, and cool it to room temperature with the furnace to obtain silicon carbide porous ceramics supported by a carbon skeleton; Step 8: Place the carbon skeleton supported silicon carbide porous ceramics into an atmosphere sintering furnace for inert atmosphere sintering, heat up to 1300°C at 5°C / min, then heat up to 1600°C at 10°C / min, keep warm for 3 hours, and then cool to room temperature with the furnace to complete the carbon thermal reduction reaction of the carbon skeleton and silicon dioxide, and obtain a mesh silicon carbide supported silicon carbide porous ceramics; Step 9: Raise the temperature of the silicon carbide porous ceramic supported by the mesh silicon carbide to 600°C at 3°C / min and keep it warm for 3 hours to remove excess carbon in the silicon carbide porous ceramic, and finally obtain 3D printed pure silicon carbide porous ceramic.

[0037] Table 1 shows the performance test data of porous silicon carbide ceramics prepared in different embodiments. It can be seen from the table that the porosity of the porous silicon carbide ceramics is between 43.74% and 50.81%, which has a high porosity; at the same time, moderate density usually means that the material has a light weight while maintaining sufficient strength; the weight of the material increases significantly after absorbing water (wet weight is greater than dry weight). The porous silicon carbide ceramic has good water absorption performance and can be used in fields that need to absorb or store water; although the weight of the material increases after absorbing water, its buoyancy in water remains stable. This may mean that the material has a certain stability and buoyancy retention ability in a liquid environment, which may have potential advantages for underwater applications or occasions requiring buoyancy.

[0038] Table 1 Performance test data of porous silicon carbide ceramics prepared in different embodiments

[0039] Figure 1 This is an XRD diagram of the porous silicon carbide ceramic sample prepared by the present invention. According to the diffraction peaks in the diagram, the sample is pure silicon carbide. The silicon carbide porous ceramics finally prepared by the present invention are composed of pure silicon carbide phase.

[0040] Figure 2 This is a cross-sectional SEM image of a porous silicon carbide ceramic sample prepared by the present invention. It can be seen from the image that the sample has a porous structure with a pore size of about 10 um; Figure 3 This is the porosity data of the porous silicon carbide ceramic sample prepared by the present invention measured by the drainage method. The porosity of the sample is about 50%. The present invention adopts the light-curing 3D printing method, does not introduce sintering aids, and does not introduce oxides during the process. It can realize the preparation of pure silicon carbide porous ceramics and improve the thermal conductivity, elastic modulus and high-temperature performance of ceramic materials.

[0041] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing 3D printed pure silicon carbide porous ceramics, characterized in that: The following steps are involved: The photosensitive resin monomer, additives and photoinitiator are mixed and stirred to obtain a premixed liquid, and then the silicon carbide mixed powder material, dispersant and thickener are added to the premixed liquid and stirred to obtain a ceramic paste; The ceramic paste is subjected to light-curing 3D printing to obtain a ceramic blank; After degreasing, sintering and decarbonizing the ceramic blank in sequence, 3D printed pure silicon carbide porous ceramics are obtained.

2. The method for preparing 3D printed pure silicon carbide porous ceramics according to claim 1, characterized in that: In terms of mass percentage, the silicon carbide mixed powder material is obtained by mixing 50%-90% silicon carbide, 10%-25% silicon dioxide and 0%-25% cured phenolic resin microspheres.

3. The method for preparing 3D printed pure silicon carbide porous ceramics according to claim 2, characterized in that: The particle size of the silicon carbide is one or more of 2-3um, 15-20um and 50-57um; The particle size of the silicon dioxide is 0.5-30 um; the particle size of the cured phenolic resin microspheres is 15-30 um.

4. The method for preparing 3D printed pure silicon carbide porous ceramics according to claim 1, characterized in that: The mass ratio of the silicon carbide mixed powder material to the premixed liquid is (2-7): (1-3); the content of the additive is 20 wt.%-30 wt.% of the total amount of the photosensitive resin; and the amount of the photoinitiator added is 2 wt.%-8 wt.% of the total amount of the photosensitive resin monomer.

5. The method for preparing 3D printed pure silicon carbide porous ceramics according to claim 1, characterized in that: The amount of the dispersant added is 2wt.%-3wt.% of the total amount of the silicon carbide mixed powder material; The thickener is added in an amount of 2 wt.%-4 wt.% of the total amount of the photosensitive resin monomer.

6. The method for preparing 3D printed pure silicon carbide porous ceramics according to claim 1, characterized in that: The photosensitive resin monomer is one or more of 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, dipentaerythritol hexaacrylate and 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate; The additive is one or more of 4,4′-isopropyldiphenol, fluorenyl acrylic acid, fluorenyl acrylic acid composite glue, and (3-glycidyl propoxy) trimethoxy silane; The photoinitiator is one or more of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, 2-isopropylthioxanthone, ethyl 4-dimethylaminobenzoate and 4-isobutylphenyl-4'-methylphenyliodine hexafluorophosphate; The dispersant is one or more of KOS110, Solsperse 85000 and 9065; The thickener is one or more of carbomer, stearic acid and BYK-405.

7. The method for preparing 3D printed pure silicon carbide porous ceramics according to claim 1, characterized in that: The method of stirring the silicon carbide mixed powder material is ball milling or homogenization; the speed of the ball milling is 300-350 r / min, and the time is 20-26h; the speed of the homogenization is 1000-2000 r / min, and the time is 1-3min.

8. The method for preparing 3D printed pure silicon carbide porous ceramics according to claim 1, characterized in that: The parameters of the light-curing 3D printing are: An ultraviolet laser with a wavelength of 355nm is used, with a power of 500mW-700mW, a scanning speed of 1200mm / s-2500mm / s, a scanning offset of 0.005-0.1mm, and a single-layer lift of 25um-70um.

9. The method for preparing 3D printed pure silicon carbide porous ceramics according to claim 1, characterized in that: The process parameters of the degreasing are: Under an inert atmosphere, heat from room temperature to 150-450°C at a heating rate of 0.25-5°C / min, keep warm for 0.5h-4h, continue to heat to 500-900°C at a heating rate of 2-5°C / min, keep warm for 0-2h, then heat to 1200-1300°C at a heating rate of 3-5°C / min, keep warm for 1-2h, and cool to room temperature; The process parameters of the sintering are: In an inert atmosphere, heat from room temperature to 1600-2200°C at a heating rate of 2-5°C / min, keep warm for 4-5h, and cool to room temperature; The process parameters of the carbon removal are: In an air atmosphere, heat from room temperature to 500-600°C at a heating rate of 2-5°C / min, keep warm for 2-3h, and cool to room temperature.

10. A 3D printed pure silicon carbide porous ceramic, characterized in that: The method is prepared by any one of claims 1 to 9.

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