CN112440467B - Porous ceramic part with high specific surface area and preparation method thereof - Google Patents
Porous ceramic part with high specific surface area and preparation method thereof Download PDFInfo
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- CN112440467B CN112440467B CN201910791900.5A CN201910791900A CN112440467B CN 112440467 B CN112440467 B CN 112440467B CN 201910791900 A CN201910791900 A CN 201910791900A CN 112440467 B CN112440467 B CN 112440467B
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
- C04B38/02—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by adding chemical blowing agents
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/10—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on aluminium oxide
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
- C04B38/10—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by using foaming agents or by using mechanical means, e.g. adding preformed foam
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2101/00—Use of unspecified macromolecular compounds as moulding material
- B29K2101/12—Thermoplastic materials
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2309/00—Use of inorganic materials not provided for in groups B29K2303/00 - B29K2307/00, as reinforcement
- B29K2309/02—Ceramics
Abstract
The invention provides a porous ceramic part based on FDM-3D printing and a preparation method thereof, wherein the method comprises the steps of taking the material system as a raw material, extruding and drawing the raw material by a screw extruder to prepare a wire material, and carrying out FDM-3D printing on the prepared wire material to obtain a molded biscuit; and sequentially carrying out the procedures of de-bonding, oxidizing and sintering on the formed biscuit to obtain the porous ceramic product. The obtained porous ceramic has high porosity and specific surface area. The deposition line of the hollow cylinder is obtained by designing and optimizing the structure of the spray head, and the porosity of the part is further increased. The expanded microspheres are introduced into the thermoplastic high polymer material, and the microspheres expand to push the peripheral polymer matrix to move by heating, so that the pore size is uniform, and the porosity is improved. By utilizing the designability of 3D printing, the porous ceramic part with high specific surface area and porosity is prepared by starting from two aspects of a material body and a printing process and cooperatively improving and optimizing.
Description
Technical Field
The invention belongs to the technical field of 3D printing ceramic parts, and particularly relates to a porous ceramic part with a high specific surface area and a preparation method thereof.
Background
The porous ceramic material is a ceramic material which is baked at high temperature to enable the interior of the material to obtain a large number of closed or communicated pore structures, and has the characteristics of low density, high permeability, high temperature resistance, corrosion resistance, good heat insulation performance and the like. The porous ceramic material has the greatest characteristic of high porosity and specific surface area as a material with great prospect, so that the porous ceramic material is widely applied to the fields of daily life and industrial production, including filtration, separation, heat insulation, sound absorption, catalyst carriers and the like.
The preparation method of the porous ceramic material mainly comprises an organic foam impregnation process, an additive pore-forming process, a particle stacking method and the like. The organic foam impregnation process is the most commonly used process at present and is invented by Schwartzwalder in 1963, and the preparation process comprises the steps of firstly making some organic foams with open-pore three-dimensional structures into specific framework structures, then pouring ceramic raw pulp into the framework structures, and placing the ceramic raw pulp into a calcining furnace for high-temperature calcination after the raw pulp is slightly dried. After roasting, the organic foam is volatilized and removed, so that the porous ceramic material with specific pore size and pore density is obtained. The manufacturing process has the advantages of simple equipment and relatively low manufacturing cost, and products with high porosity and high strength can be prepared by the process. However, the above-mentioned methods for manufacturing porous ceramics also rely on a template or a mold to control the shape, which is difficult to realize for porous ceramics with complicated structure and shape.
With the maturity of electronic information technology, 3D printing also happened and popularized, opening the era of mold-free manufacturing. Journal of the academician of economics describes that digital manufacturing techniques, such as 3D printing, will alter the mode of production in the manufacturing industry and thus change the mode of operation of the industrial chain. 3D printing, also known as Additive Manufacturing (AM), occurred in the 70 s of the 20 th century. According to the definition given by the american society for testing and materials international standards organization F42 technical committee for additive manufacturing: 3D printing is a process of manufacturing objects from layers of material connected together according to 3D model data. The 3D printing is applied to the preparation of the porous ceramic, so that the research and development period and cost can be reduced, and the forming efficiency can be improved.
Chinese patent document CN108101574A discloses a method for preparing a ceramic porous piece by 3D printing and a ceramic porous piece, which is prepared by the following preparation method: (1) blank forming: loading the ceramic paste for 3D printing into a bin of a desktop printer, and forming a ceramic porous piece blank with a design specification at room temperature by adopting a 3D printing technology; (2) and (3) blank curing: placing the ceramic porous member blank formed in the blank forming step in a carbon dioxide atmosphere, and gradually drying, polymerizing and curing; (3) and (3) a finished product preparation step: and (3) placing the blank of the ceramic porous piece cured in the blank curing step into an air furnace, and carrying out integrated degreasing-sintering treatment to obtain the required ceramic porous piece.
Chinese patent document CN105645840A discloses a porous ceramic microsphere composite material for 3D printing, which mainly comprises porous ceramic microspheres and thermoplastic resin, wherein the porous ceramic microspheres account for 80-99% of the total weight, the thermoplastic resin accounts for 1-20% of the total weight, and the ceramic material for 3D printing is prepared by extrusion granulation in a double-screw extruder.
Chinese patent document CN108178659A discloses a molding material for 3D printing, which is composed of the following components: the molding material comprises graded modified alumina powder, yellow dextrin powder and a binder, wherein the binder accounts for 5-50% of the molding material by mass, and the dosage ratio of the graded modified alumina powder to the yellow dextrin powder is (63-97) to (15-25).
In a few published patents for preparing porous ceramics by 3D printing, there are few reports on methods for improving the porosity and specific surface area of a formed part, and the porosity and specific surface area are important characteristic parameters of porous ceramics and play a key role in the application field thereof.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention aims to provide a spray head for preparing a porous ceramic part with high specific surface area based on Fused Deposition Modeling (FDM)3D printing; another object of the present invention is to provide a material system which can be printed by means of the above-mentioned nozzles to give porous ceramic articles with a high specific surface area; it is a further object of the present invention to provide a method for preparing a porous ceramic article having a high specific surface area based on the above showerhead using the above material system; it is a further object of the present invention to provide a porous ceramic article having a high specific surface area obtained by said preparation method using said material system and said spray head.
FDM is formed by melting materials at high temperature, extruding the materials into filaments through a spray head, and stacking and forming the filaments on a component platform. FDM is the most common 3D printing technology, and its working process is: under the control of a computer, according to the section profile of a part determined by a three-dimensional model, a printing spray head moves in the horizontal X direction, a component platform moves in the horizontal Y direction, meanwhile, a wire feeding mechanism feeds thermoplastic plastic wires into the spray head, the thermoplastic plastic wires become a flowable melt after being heated, and then the melt is extruded through a nozzle and deposited on the platform.
The purpose of the invention is realized by the following technical scheme:
the invention provides a sprayer based on FDM-3D printing, wherein the sprayer comprises a sprayer upper part, a sprayer lower part, a baffle and a baffle connecting piece;
the structure of the upper spray head part is cylindrical, the structure of the lower spray head part is a cone frustum structure, a feed port is formed at one end of the upper spray head part, the other end of the upper spray head part is connected with the end, with the larger diameter, of the lower spray head part, and a discharge port is formed at the end, with the smaller diameter, of the lower spray head part;
the baffle is flush with the discharge hole in the direction vertical to the bottom surface, and a C-shaped gap is formed between the baffle and the discharge hole; the baffle is connected with the upper part of the spray head or the lower part of the spray head through a baffle connecting piece.
According to the invention, the structure of the baffle is an opposite structure, the baffle is flush with the discharge hole in the direction vertical to the bottom surface, and a C-shaped gap is formed between the baffle and the discharge hole.
The invention provides a material system suitable for FDM-3D printing, wherein the material system comprises a thermoplastic polymer composition, expandable microspheres, rigid particles and optional rare earth additives, wherein the initial foaming temperature of the expandable microspheres is lower than the processing temperature of the material system for processing into a wire for FDM-3D printing and the processing temperature of FDM-3D printing.
According to the invention, the thermoplastic polymer composition accounts for 15-25wt% of the total mass of the material system, the expandable microspheres account for 2-6wt% of the total mass of the material system, the rigid particles account for 72-80wt% of the total mass of the material system, and the rare earth additive accounts for 0-1.5wt% of the total mass of the material system.
According to the present invention, the thermoplastic polymer composition includes a thermoplastic polymer, an internal lubricant, and a tackifying resin.
Preferably, the thermoplastic polymer composition comprises 60-80wt% of thermoplastic polymer, 10-20wt% of internal lubricant and 10-20wt% of tackifying resin.
Preferably, the rigid particles have a particle size in the micrometer range, for example, in one or more combinations of 1 μm, 5 μm, 10 μm and 30 μm; for example, the rigid particles are selected from the group consisting of 70 parts of rigid particles having a particle size of 30 μm, 25 parts of rigid particles having a particle size of 5 μm, and 5 parts of rigid particles having a particle size of 1 μm; or a combination of 50 parts of rigid particles having a particle size of 30 μm and 50 parts of rigid particles having a particle size of 1 μm; the specific rigid particles are selected from the combination of 70 parts of alumina particles with the particle size of 30 mu m, 25 parts of alumina particles with the particle size of 5 mu m and 5 parts of alumina particles with the particle size of 1 mu m; or a combination of 50 parts of alumina particles having a particle size of 30 μm and 50 parts of alumina particles having a particle size of 1 μm.
The invention provides a porous ceramic part which is obtained by printing the material system through FDM-3D printing equipment comprising the nozzle based on FDM-3D printing.
Preferably, the material system is uniformly mixed, plasticized and granulated by a double-screw extruder, and then drawn by a single-screw extruder, wherein the diameter of the drawn wire is 1.75mm, and the wire is printed by FDM-3D printing equipment comprising the nozzle based on FDM-3D printing to obtain the porous ceramic part.
The present invention provides a method for preparing a porous ceramic having a high specific surface area, the method comprising the steps of:
1) the material system suitable for FDM-3D printing is adopted as a raw material, the raw material is extruded and drawn by a screw extruder to prepare a wire material, and the prepared wire material is subjected to FDM-3D printing to obtain a molded biscuit;
2) and sequentially carrying out the procedures of de-bonding, oxidizing and sintering on the formed biscuit to obtain the porous ceramic product.
According to the invention, in the step 1), an FDM-3D printing device comprising the nozzle based on FDM-3D printing is used in the FDM-3D printing process. The hollow cylindrical deposition line can be prepared by the nozzle based on FDM-3D printing, wherein the inner diameter of the deposition line is 0.3-0.6mm, and the outer diameter of the deposition line is 1.2-1.5 mm.
The invention provides a porous ceramic product, which is prepared by the method for preparing the porous ceramic with high specific surface area.
Preferably, the article comprises macro-engineered pores, decomposed pores and expanded pores, the macro-engineered pores being pores formed by selectively depositing material by controlling the print trajectory at the time of 3D printing.
Preferably, the porosity and the specific surface area of the porous ceramic part are high and can reach 48-72% through mercury intrusion instrument test; the specific surface area is 260-350m according to GB/T6609.35 by adopting BET multilayer adsorption2/g。
The invention has the beneficial effects that:
the invention provides a porous ceramic part based on FDM-3D printing and a preparation method thereof, and the obtained porous ceramic has high porosity and specific surface area. The expanded microspheres are introduced into the thermoplastic high polymer material, and the microspheres expand to push the peripheral polymer matrix to move by heating, so that the pore size is uniform, and the porosity is improved. The deposition line of the hollow cylinder is obtained by designing and optimizing the structure of the spray head, and the porosity of the part is further increased. By utilizing the designability of 3D printing, the porous ceramic part with high specific surface area and porosity is prepared by starting from two aspects of a material body and a printing process and cooperatively improving and optimizing.
Drawings
Fig. 1 is a front view of the spray head according to the present invention.
Fig. 2 is a top view of the showerhead of the present invention.
Fig. 3 is a bottom view of the showerhead of the present invention.
FIG. 4 is a cross-sectional view taken along line A-A of the showerhead of the present invention.
FIG. 5 is a sectional view taken along line B-B of the showerhead of the present invention.
Fig. 6 shows the parts of the invention after 3D printing (left) and after high temperature sintering (right).
Detailed Description
[ spray head ]
As described above, the present invention provides a showerhead based on FDM-3D printing, the showerhead including a showerhead upper part, a showerhead lower part, a baffle, and a baffle connection member;
the structure of the upper spray head part is cylindrical, the structure of the lower spray head part is a cone frustum structure, a feed port is formed at one end of the upper spray head part, the other end of the upper spray head part is connected with the end, with the larger diameter, of the lower spray head part, and a discharge port is formed at the end, with the smaller diameter, of the lower spray head part;
the baffle is flush with the discharge hole in the direction vertical to the bottom surface, and a C-shaped gap is formed between the baffle and the discharge hole; the baffle is connected with the upper part of the spray head or the lower part of the spray head through a baffle connecting piece.
In one embodiment, the height of the upper part of the spray head is 10-30 mm; the inner diameter of the upper part of the spray head is 4-12 mm; illustratively, the height of the upper part of the spray head is 20 mm; the inner diameter of the upper part of the spray head is 8 mm.
In one embodiment, the height of the lower part of the spray head is 10-30 mm; the inner diameter of the end with the larger diameter of the lower part of the spray head is the same as that of the upper part of the spray head, and the inner diameter of the end with the smaller diameter of the lower part of the spray head is 1.0-1.5 mm; illustratively, the height of the showerhead lower member is 20 mm; the inner diameter of the end with the larger diameter of the lower part of the spray head is 8mm, and the inner diameter of the end with the smaller diameter of the lower part of the spray head is 1.2 mm.
In one embodiment, the baffle connector is a cylindrical structure.
In one specific embodiment, the structure of the baffle (3) is an opposite structure, and the baffle (3) is flush with the discharge hole in the direction perpendicular to the bottom surface and forms a C-shaped gap with the discharge hole.
In a specific embodiment, the opening radian of the C-shaped gap is pi/6-pi/4 rad, the part without the opening is in the shape of a concentric ring, the outer diameter of the concentric ring is 0.8-1mm, and the inner diameter of the concentric ring is 0.4-0.6 mm.
In the invention, when the nozzle based on FDM-3D printing is adopted, in the process of melting and extruding the thermoplastic polymer material, the thermoplastic polymer material from the C-shaped gap has an extrusion swelling effect, and the part of the C-shaped gap which is not communicated is compensated by the swelled thermoplastic polymer material, namely, a hollow cylindrical structure can be formed by the deposition line behind the nozzle based on FDM-3D printing. Illustratively, the deposited lines have an inner diameter of 0.3 to 0.6mm and an outer diameter of 1.2 to 1.5 mm.
The extrusion swelling effect is a typical expression that a thermoplastic polymer has viscoelasticity, and after passing through a narrow die, the molecular chain generates relative displacement, namely viscous flow and elastic flow caused by conformational change. The baffle connecting piece provides the support for the baffle, makes the baffle not take place deformation and displacement change under the impact of fuse-element, and the baffle connecting piece is located C font space top simultaneously, has shear deformation's effect to the fuse-element in the shower nozzle, further aggravates the effect of the swelling of extruding of fuse-element.
[ Material System ]
The invention also provides a material system suitable for FDM-3D printing, which comprises a thermoplastic polymer composition, expandable microspheres, rigid particles and optional rare earth additives, wherein the initial foaming temperature of the expandable microspheres is lower than the processing temperature of the material system for processing into the wire for FDM-3D printing and the processing temperature of FDM-3D printing.
In one embodiment, the thermoplastic polymer composition includes a thermoplastic polymer, an internal lubricant, and a tackifying resin.
Illustratively, the thermoplastic polymer is selected from one or more of ethylene-vinyl acetate copolymer (EVA) and ethylene-octene copolymer. Preferably, the melting point of the thermoplastic polymer is not more than 100 ℃.
Illustratively, the tackifying resin is selected from one or more of terpene resin, C5 petroleum resin, C9 petroleum resin, hydrogenated terpene resin, and the like, which can improve the interlayer bonding strength of the printed product and ensure the mechanical strength of the molded biscuit.
Illustratively, the internal lubricant is selected from at least one of stearic acid, sodium stearate, magnesium stearate, and the like, which is used to reduce intermolecular friction.
In one embodiment, the expandable microspheres are physical blowing agents, such as those selected from 095DU120 manufactured by akzo nobel Expancel, which is a thermally expandable polymeric microsphere having a core-shell structure, illustratively, a liquid low boiling alkane in the core and a thermoplastic polymer with good barrier properties in the shell.
As mentioned above, the initial foaming temperature of the expandable microspheres is lower than the processing temperature of the material system for processing into the filament for FDM-3D printing and the processing temperature for FDM-3D printing, which is set to ensure that the expandable microspheres do not foam during the filament preparation and 3D printing processes. For example, when the melting point of the thermoplastic polymer is not more than 100 ℃, the initial foaming temperature of the expandable microspheres is more than 100 ℃, and more for example, more than or equal to 110 ℃, or more than or equal to 120 ℃. The expandable microspheres can be foamed in a debonding process after the 3D printing step (because the temperature of the process is higher than the initial foaming temperature), so that the peripheral polymer matrix is pushed to move, the pore size can be further uniform, and the porosity is improved.
In a toolIn an embodiment, the rigid particles are selected from alumina particles; illustratively, the alumina particles are γ -Al2O3。
In one embodiment, the rigid particles have a particle size in the micrometer range, for example, in one or more combinations of 1 μm, 5 μm, 10 μm, and 30 μm; for example, the rigid particles are selected from the group consisting of 70 parts of rigid particles having a particle size of 30 μm, 25 parts of rigid particles having a particle size of 5 μm, and 5 parts of rigid particles having a particle size of 1 μm; or a combination of 50 parts of rigid particles having a particle size of 30 μm and 50 parts of rigid particles having a particle size of 1 μm; the specific rigid particles are selected from the combination of 70 parts of alumina particles with the particle size of 30 mu m, 25 parts of alumina particles with the particle size of 5 mu m and 5 parts of alumina particles with the particle size of 1 mu m; or a combination of 50 parts of alumina particles having a particle size of 30 μm and 50 parts of alumina particles having a particle size of 1 μm. The addition of the rigid particles can prepare ceramic products, particularly reasonable grading of particle size is carried out, so that the density of the green bodies after later sintering is ensured, the mechanical strength of the green bodies is ensured, and the specific surface area of the ceramic products can be effectively increased while high porosity is maintained.
According to the invention, the material system contains a high-content thermoplastic polymer used as a toughening agent, so that the prepared wire material can have certain impact toughness after being filled with high-content rigid particles, and the feeding requirement of FDM-3D printing is met.
In one embodiment, the rare earth additive is selected from La2O3And CeO2At least one of (1). The addition of the rare earth additive can protect hydroxyl on the surface of the aluminum oxide, inhibit sintering and phase change, reduce the damage of high temperature to a pore structure and improve the high-temperature thermal stability of the aluminum oxide.
In a specific embodiment, the material system has a melt index of greater than 30g/10min (according to ISO1133, test conditions 125 ℃, 0.325 kg).
In one embodiment, the material system is uniformly mixed, plasticized and granulated by a double-screw extruder, and then drawn by a single-screw extruder, wherein the diameter of the drawn wire is 1.75mm, and the drawn wire can be directly used for FDM-3D printing.
In one embodiment, the material system can be printed by the above-described inkjet head to obtain a porous ceramic article having a high specific surface area.
[ Cylinder type deposition line ]
The invention also provides a hollow cylindrical deposition line, wherein the deposition line is prepared by the nozzle based on FDM-3D printing, the inner diameter of the deposition line is 0.3-0.6mm, and the outer diameter of the deposition line is 1.2-1.5 mm.
Further, the deposited lines are prepared by the material system suitable for FDM-3D printing through the sprayer based on FDM-3D printing, and the inner diameter of each deposited line is 0.3-0.6mm, and the outer diameter of each deposited line is 1.2-1.5 mm.
[ method for preparing porous ceramics having a high specific surface area ]
The present invention also provides a method for preparing a porous ceramic having a high specific surface area, the method comprising the steps of:
1) the material system is adopted as a raw material, and is extruded and drawn by a screw extruder (which can be a single screw extruder or a double screw extruder) to prepare a wire material, and the prepared wire material is subjected to FDM-3D-based printing to obtain a molded biscuit;
2) and sequentially carrying out the procedures of de-bonding, oxidizing and sintering on the formed biscuit to obtain the porous ceramic product.
In the step 1), the spray head is used in the FDM-3D printing process. The hollow cylindrical deposition line can be prepared by the nozzle based on FDM-3D printing, wherein the inner diameter of the deposition line is 0.3-0.6mm, and the outer diameter of the deposition line is 1.2-1.5 mm.
In the step 1), the material system is uniformly mixed, plasticized and granulated by a double-screw extruder, and then drawn by a single-screw extruder, wherein the diameter of the drawn wire is 1.75mm, and the drawn wire can be directly used for FDM-3D printing.
In the step 2), in the debonding procedure, the temperature is raised to 500-; in the oxidation procedure, the temperature is raised to 800-1100 ℃ at the temperature rise speed of 3-6 ℃/min, and the heat preservation time is 2-4 hours; in the sintering process, the temperature is raised to 1100-1300 ℃ at the temperature rise speed of 8-15 ℃/min, and the heat preservation time is 4-8 hours.
In the step 2), the temperature is increased to 700 ℃ at the temperature increasing speed of 2 ℃/min in the debonding process, and the heat preservation time is 1 hour; in the oxidation procedure, the temperature is raised to 1000 ℃ at the temperature rise speed of 4 ℃/min, and the heat preservation time is 3 hours; in the sintering process, the temperature is increased to 1200 ℃ at the temperature rising speed of 10 ℃/min, and the heat preservation time is 6 hours.
In the step 2), in the debonding process, when the temperature is raised to 120 ℃, the expandable microspheres can foam to push the surrounding matrix material to move, so that a product with uniform pore size can be further prepared, and the porosity of the product can be improved.
[ porous ceramic product ]
The invention also provides a porous ceramic product which is prepared by the method for preparing the porous ceramic with high specific surface area.
In one embodiment, the article includes macro-engineered pores, decomposed pores, and expanded pores, the macro-engineered pores being pores formed by selectively depositing material by controlling a print trajectory during 3D printing. The decomposition pores are formed in the framework in a certain size range in the originally occupied space after the thermoplastic polymer is decomposed after being combusted. The expanded pores are pores formed by the expanded microspheres after being heated and expanded.
In one specific embodiment, the porosity and the specific surface area of the porous ceramic part are high and can reach 48 to 72 percent through a mercury porosimeter test; the specific surface area is 260-350m according to GB/T6609.35 by adopting BET multilayer adsorption2/g。
In one embodiment, the porous ceramic article is prepared using an FDM-based 3D printing apparatus including the showerhead described above.
Illustratively, the material system is prepared by adopting the material system through an FDM-based 3D printing device comprising the spray head.
The preparation method of the present invention will be described in further detail with reference to specific examples. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.
The experimental methods used in the following examples are all conventional methods unless otherwise specified; reagents, materials and the like used in the following examples are commercially available unless otherwise specified.
The EVA used in the following examples is Dupont Elvax 200W, the terpene resin is Zhengzhou Huamai chemical T90, and the expandable microspheres are Akzo Nobel Expancel 095DU120, gamma-Al2O3New material from Hangzhou Jikang, La2O3、CeO2And stearic acid was purchased from alatin.
The 3D printer used in the following examples was a three-dimensional high-tech, model number S1, which was a marine source, wherein the spray head used in comparative example 1 was a one-component spray head, and the spray heads used in examples 3 to 8 were the spray heads described in example 1.
Comparative example 1
20wt% of thermoplastic polymer composition, 79 wt% of gamma-Al2O3Granules, 0.5 wt% La2O3And 0.5 wt% CeO2Melt blending to prepare 1.75mm diameter wire. Wherein the thermoplastic polymer composition comprises 70 wt% of EVA, 20wt% of terpene resin and 10 wt% of stearic acid; gamma-Al2O3Has a particle diameter of 10 μm.
Adopting FDM-3D printing equipment to print the silk material, wherein the printing parameters are as follows:
the printing temperature is 100 ℃, the hot bed temperature is 40 ℃, the printing speed is 40mm/s, the filling rate is 100%, and the layer thickness is 0.4 mm. Preparing a latticed cube with the side length of 20mm, then putting the latticed cube into a sintering furnace, heating to 700 ℃ at the heating rate of 2 ℃/min, and keeping the temperature for 1 hour; in the oxidation procedure, the temperature is raised to 1000 ℃ at the temperature rise speed of 4 ℃/min, and the heat preservation time is 3 hours; in the sintering process, the temperature is increased to 1200 ℃ at the temperature rising speed of 10 ℃/min, and the heat preservation time is 6 hours. Finally obtaining the sintered alumina ceramic.
Example 1
The embodiment provides FDM-3D printing equipment, wherein a printing nozzle upper part 1, a nozzle lower part 2, a baffle 3 and a baffle connecting piece 4 are used in the printing equipment; the structure of the upper spray head component 1 is cylindrical, the structure of the lower spray head component 2 is a cone frustum structure, a feed inlet is formed at one end of the upper spray head component 1, the other end of the upper spray head component 1 is connected with the larger-diameter end of the lower spray head component 2, and a discharge outlet is formed at the smaller-diameter end of the lower spray head component 2; the baffle 3 is flush with the discharge hole in the direction vertical to the bottom surface, and a C-shaped gap is formed between the baffle and the discharge hole; the baffle 3 is connected with the spray head upper part 1 or the spray head lower part 2 through a baffle connecting piece 4;
the height of the upper part 1 of the spray head is 20 mm; the inner diameter of the upper part 1 of the spray head is 8 mm; the height of the lower part 2 of the spray head is 20 mm; the inner diameter of the larger end of the lower spray head part 2 is 8mm, and the inner diameter of the smaller end of the lower spray head part 2 is 1.2 mm; the structure of baffle 3 is different in nature structure, baffle 3 flushes with the discharge gate on the direction of perpendicular to bottom surface, and forms C font space between with the discharge gate. The radian of the opening of the C-shaped gap is pi/6-pi/4 rad, the part without the opening is in a concentric ring shape, the outer diameter of the concentric ring is 0.9mm, and the inner diameter of the concentric ring is 0.5 mm.
Example 2
When the nozzle based on FDM-3D printing described in embodiment 1 is used, in the process of melt extrusion of a thermoplastic polymer material, the thermoplastic polymer material coming out of the C-shaped gap has an extrusion swelling effect, and the unconnected portion of the C-shaped gap is compensated by the swollen thermoplastic polymer material, that is, a hollow cylindrical structure can be formed by the deposition line behind the nozzle based on FDM-3D printing. The inner diameter of the deposition line is 0.3-0.6mm, and the outer diameter is 1.2-1.5 mm.
Example 3
18 wt% of thermoplastic polymer composition, 2 wt% of expandable microspheres and 79 wt% of gamma-Al2O3Granules, 0.5 wt% La2O3And 0.5 wt% CeO2Melt blending to prepare 1.75mm diameter wire. Wherein the thermoplastic polymer composition comprises 70 wt% of EVA, 20wt% of terpene resin and 10 wt% of stearic acid; gamma-Al2O3Has a particle diameter of 10 μm.
And printing the silk material by adopting FDM-3D printing equipment to obtain a deposited line with the inner diameter of 0.3-0.6mm and the outer diameter of 1.2-1.5mm, wherein the printing parameter setting is the same as that of the comparative example 1. Finally obtaining the sintered alumina ceramic.
Example 4
20wt% of thermoplastic polymer composition, 79 wt% of gamma-Al2O3Granules, 0.5 wt% La2O3And 0.5 wt% CeO2Melt blending to prepare 1.75mm diameter wire. Wherein the thermoplastic polymer composition comprises 70 wt% of EVA, 20wt% of terpene resin and 10 wt% of stearic acid; gamma-Al2O3Has a particle diameter of 10 μm.
The printing of the wire is carried out by adopting the FDM-3D printing equipment in the embodiment 1, the deposition line with the size of the embodiment 2 is obtained by printing, and the printing parameter setting is the same as that in the comparative example 1. Finally obtaining the sintered alumina ceramic.
Example 5
18 wt% of thermoplastic polymer composition, 2 wt% of expandable microspheres and 79 wt% of gamma-Al2O3Granules, 0.5 wt% La2O3And 0.5 wt% CeO2Melt blending to prepare 1.75mm diameter wire. Wherein the thermoplastic polymer composition comprises 70 wt% of EVA, 20wt% of terpene resin and 10 wt% of stearic acid; gamma-Al2O3Has a particle diameter of 10 μm.
The printing of the wire is carried out by adopting the FDM-3D printing equipment in the embodiment 1, the deposition line with the size of the embodiment 2 is obtained by printing, and the printing parameter setting is the same as that in the comparative example 1. Finally obtaining the sintered alumina ceramic.
Example 6
16 wt% of thermoplastic polymer composition, 4 wt% of expandable microspheres and 79 wt% of gamma-Al2O3Granules, 0.5 wt% La2O3And 0.5 wt% CeO2Melt blending to prepare 1.75mm diameter filamentsA material is provided. Wherein the thermoplastic polymer composition comprises 70 wt% of EVA, 20wt% of terpene resin and 10 wt% of stearic acid; gamma-Al2O3Has a particle diameter of 10 μm.
The printing of the wire is carried out by adopting the FDM-3D printing equipment in the embodiment 1, the deposition line with the size of the embodiment 2 is obtained by printing, and the printing parameter setting is the same as that in the comparative example 1. Finally obtaining the sintered alumina ceramic.
Example 7
16 wt% of thermoplastic polymer composition, 4 wt% of expandable microspheres and 79 wt% of gamma-Al2O3Granules, 0.5 wt% La2O3And 0.5 wt% CeO2Melt blending to prepare 1.75mm diameter wire. Wherein the thermoplastic polymer composition comprises 70 wt% of EVA, 20wt% of terpene resin and 10 wt% of stearic acid; gamma-Al2O370 parts of 30 μm, 25 parts of 5 μm and 5 parts of 1 μm.
The printing of the wire is carried out by adopting the FDM-3D printing equipment in the embodiment 1, the deposition line with the size of the embodiment 2 is obtained by printing, and the printing parameter setting is the same as that in the comparative example 1. Finally obtaining the sintered alumina ceramic.
Example 8
16 wt% of thermoplastic polymer composition, 4 wt% of expandable microspheres and 79 wt% of gamma-Al2O3Granules, 0.5 wt% La2O3And 0.5 wt% CeO2Melt blending to prepare 1.75mm diameter wire. Wherein the thermoplastic polymer composition comprises 70 wt% of EVA, 20wt% of terpene resin and 10 wt% of stearic acid; gamma-Al2O350 parts of the mixture with the particle size of 30 μm and 50 parts of the mixture with the particle size of 1 μm.
The printing of the wire is carried out by adopting the FDM-3D printing equipment in the embodiment 1, the deposition line with the size of the embodiment 2 is obtained by printing, and the printing parameter setting is the same as that in the comparative example 1. Finally obtaining the sintered alumina ceramic.
Testing the porosity of the sintered part by using a mercury porosimeter; the specific surface area of the sintered parts was measured according to GB/T6609.35 using BET multilayer adsorption and the results are given in Table 1:
TABLE 1 porosity and specific surface area of the articles of comparative example 1 and examples 3-8
| Comparative example 1 | Example 3 | Example 4 | Example 5 | Example 6 | Example 7 | Example 8 | |
| Porosity/% | 48.3 | 52.6 | 58.1 | 61.3 | 63.9 | 62.8 | 61.7 |
| Specific surface area/m2/g | 232 | 239 | 286 | 283 | 305 | 345 | 332 |
As can be seen from table 1, comparing comparative example 1 and example 3, the porosity of the article can be effectively increased by adding expandable microspheres; compared with the comparative example 1 and the example 4, the deposition lines are in a hollow cylinder structure through the structural design of the spray head, so that the porosity and the specific surface area of the part can be greatly improved; comparative examples 5 to 8 by treatment with gamma-Al2O3The reasonable grading of the particle size can effectively improve the specific surface area of a finished piece while keeping high porosity.
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (12)
1. A porous ceramic part is obtained by printing a material system suitable for FDM-3D printing through an FDM-3D printing device with a sprayer based on FDM-3D printing;
the nozzle based on FDM-3D printing comprises an upper nozzle part (1), a lower nozzle part (2), a baffle (3) and a baffle connecting piece (4);
the structure of the upper spray head component (1) is cylindrical, the structure of the lower spray head component (2) is a truncated cone structure, a feed inlet is formed at one end of the upper spray head component (1), the other end of the upper spray head component (1) is connected with the end with the larger diameter of the lower spray head component (2), and a discharge outlet is formed at the end with the smaller diameter of the lower spray head component (2);
the baffle (3) is flush with the discharge hole in the direction vertical to the bottom surface, and a C-shaped gap is formed between the baffle and the discharge hole; the baffle (3) is connected with the upper part (1) of the spray head or the lower part (2) of the spray head through a baffle connecting piece (4);
the material system comprises a thermoplastic polymer composition, expandable microspheres, rigid particles, and optionally rare earth additives, wherein the expandable microspheres have an initial foaming temperature that is higher than the processing temperature of the material system into a wire for FDM-3D printing and the processing temperature of FDM-3D printing.
2. The porous ceramic article of claim 1 wherein the thermoplastic polymer composition comprises 15-25wt% of the total mass of the material system, the expandable microspheres comprise 2-6wt% of the total mass of the material system, the rigid particles comprise 72-80wt% of the total mass of the material system, and the rare earth additive comprises 0-1.5wt% of the total mass of the material system;
the thermoplastic polymer composition comprises 60-80wt% of thermoplastic polymer, 10-20wt% of internal lubricant and 10-20wt% of tackifying resin;
the rigid particles are gamma-Al2O3The rare earth additive is selected from La2O3And CeO2At least one of; the core of the expandable microsphere is liquid alkane with low boiling point, and the shell is thermoplastic polymer with good barrier property.
3. The porous ceramic article of claim 1 wherein the rigid particles have a particle size on the micron scale of one or more combinations of 1, 5, 10 and 30 μm.
4. The porous ceramic article of claim 1 wherein the rigid particles are selected from the group consisting of 70 parts rigid particles having a particle size of 30 μ ι η, 25 parts rigid particles having a particle size of 5 μ ι η, and 5 parts rigid particles having a particle size of 1 μ ι η; or a combination of 50 parts of rigid particles having a particle size of 30 μm and 50 parts of rigid particles having a particle size of 1 μm; the specific rigid particles are selected from the combination of 70 parts of alumina particles with the particle size of 30 mu m, 25 parts of alumina particles with the particle size of 5 mu m and 5 parts of alumina particles with the particle size of 1 mu m; or a combination of 50 parts of alumina particles having a particle size of 30 μm and 50 parts of alumina particles having a particle size of 1 μm.
5. The porous ceramic part as claimed in claim 1, wherein the baffle (3) has a special-shaped structure, and the baffle (3) is flush with the discharge port in a direction perpendicular to the bottom surface and forms a C-shaped gap with the discharge port.
6. The porous ceramic article according to claim 1, wherein the material system is plasticized and pelletized by a twin screw extruder after being homogeneously mixed, and then drawn by a single screw extruder with a drawn wire diameter of 1.75mm, and the wire is printed by the FDM-3D printing apparatus to obtain the porous ceramic article.
7. A method for preparing a porous ceramic having a high specific surface area, the method comprising the steps of:
1) preparing a wire material by using the material system in the porous ceramic part as a raw material and extruding and drawing the raw material through a screw extruder, and performing FDM-3D-based printing on the prepared wire material to obtain a molded biscuit;
2) sequentially carrying out the procedures of de-bonding, oxidizing and sintering on the molded biscuit to obtain a porous ceramic workpiece;
in the step 1), in the FDM-3D-based printing process, FDM-3D printing equipment comprising a nozzle based on FDM-3D printing is used;
the nozzle based on FDM-3D printing comprises an upper nozzle part (1), a lower nozzle part (2), a baffle (3) and a baffle connecting piece (4);
the structure of the upper spray head component (1) is cylindrical, the structure of the lower spray head component (2) is a truncated cone structure, a feed inlet is formed at one end of the upper spray head component (1), the other end of the upper spray head component (1) is connected with the end with the larger diameter of the lower spray head component (2), and a discharge outlet is formed at the end with the smaller diameter of the lower spray head component (2);
the baffle (3) is flush with the discharge hole in the direction vertical to the bottom surface, and a C-shaped gap is formed between the baffle and the discharge hole; the baffle (3) is connected with the upper part (1) of the spray head or the lower part (2) of the spray head through a baffle connecting piece (4).
8. The method of claim 7, wherein the baffle (3) is of a special-shaped structure, and the baffle (3) is flush with the discharge port in a direction perpendicular to the bottom surface and forms a C-shaped gap with the discharge port.
9. The method according to claim 7, wherein a hollow cylindrical deposited line with an inner diameter of 0.3-0.6mm and an outer diameter of 1.2-1.5mm can be prepared by the nozzle based on FDM-3D printing.
10. A porous ceramic article produced by the method for producing a porous ceramic having a high specific surface area according to any one of claims 7 to 9.
11. The article of claim 10, wherein the article comprises macro-engineered pores, decomposed pores, and expanded pores, the macro-engineered pores being pores formed by selectively depositing material by controlling print trajectories during 3D printing.
12. The article of claim 10 or 11, wherein the porous ceramic article has a high porosity and a high specific surface area, as measured by mercury intrusion porosimetry, ranging from 48% to 72%; the specific surface area is 260-350m according to GB/T6609.35 by adopting BET multilayer adsorption2/g。
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