Photopolymerization 3D Printing of Alumina Ceramic Microspheres, Preparation Methods and Applications

Abstract

This invention belongs to the field of alumina ceramic technology, specifically relating to photopolymerization 3D printing of alumina ceramic microspheres, their preparation method, and applications. The method includes: mixing α-Al₂O₃ powder with anhydrous ethanol, heating under reflux, adding ethyl acetate, stirring continuously, and then removing the solvent to obtain a pretreated powder; mixing this powder with an active diluent, a photoinitiator, and a dispersant to prepare a ceramic slurry; designing and arranging spherical models in an array, slicing to generate a printing file, adding the ceramic slurry to a photopolymerization 3D printer to print a microsphere array preform, removing the support to obtain a spherical preform, and sintering to obtain the target ceramic microspheres. This method achieves the preparation of a ceramic slurry with high solid content, low viscosity, and stable dispersion; simultaneously, combining the array forming advantages of DLP photopolymerization 3D printing, the diameter of the microspheres can be precisely controlled, resulting in microspheres with high sphericity. This preparation method is simple and controllable, enabling mass production of alumina ceramic microspheres.

Description

Technical Field

[0001] This invention belongs to the field of alumina ceramic technology, specifically relating to photopolymerization 3D printing of alumina ceramic microspheres, their preparation methods, and applications. Background Technology

[0002] Alumina ceramic microspheres possess excellent properties such as high strength, high hardness, high temperature resistance, and corrosion resistance, making them widely applicable in grinding and polishing, catalyst supports, and filtration separation. In particular, alumina ceramic microspheres with high sphericity and controllable size ensure uniform stress on the grinding media during grinding, thereby improving grinding efficiency. In the field of catalyst supports, their regular spherical structure optimizes hydrodynamic properties and enhances catalytic activity.

[0003] Currently, the main methods for preparing alumina ceramic microspheres include spray drying, rolling, and sol-gel methods. However, these traditional methods have many shortcomings: microspheres prepared by spray drying have low sphericity and a wide size distribution, making precise control difficult; rolling is more suitable for preparing large-sized microspheres, and is difficult and inefficient for microspheres with a diameter of less than 1 mm; the sol-gel method is complex and costly, making it difficult to achieve large-scale mass production.

[0004] Photopolymerization 3D printing technology, with its advantages of high precision, high forming efficiency, and customizability, provides a new approach for the precise preparation of ceramic microspheres. However, the core bottleneck in the preparation of alumina ceramic microspheres by photopolymerization 3D printing lies in the performance control of the ceramic slurry. This technology requires the slurry to simultaneously possess high solid content, low viscosity, long-term dispersion stability, and excellent photopolymerization responsiveness. In existing technologies, the pretreatment of alumina powder often employs simple vacuum drying or atmospheric pressure drying methods, which are difficult to completely remove adsorbed water from the powder surface and easily lead to secondary agglomeration of the powder, thus affecting the dispersion stability of the slurry. At the same time, the use of a single dispersant in the slurry dispersion process makes it difficult to achieve low viscosity control under high solid content, ultimately adversely affecting the forming quality of the subsequent printed preform and the sphericity of the finished microspheres.

[0005] Furthermore, while existing technologies include methods for modifying alumina powder using composite coupling agents, most are geared towards general hydrophobic modification scenarios and fail to meet the specific process requirements of photopolymerization 3D printing. Moreover, the pretreatment process exhibits poor synergy with subsequent slurry preparation and printing processes, making it difficult to guarantee the dimensional accuracy and sphericity of the final product. Therefore, developing a method adapted to photopolymerization 3D printing processes that enables controllable size and high sphericity of alumina ceramic microspheres is of significant practical importance. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing photopolymerizable 3D printed alumina ceramic microspheres. This method achieves the preparation of ceramic slurry with high solid content, low viscosity, and stable dispersion through process optimization. Simultaneously, by combining the array-forming advantages of DLP photopolymerizable 3D printing, the diameter of the microspheres can be precisely controlled, resulting in microspheres with high sphericity. This preparation method is simple and controllable, requires no complex equipment, and enables mass production of alumina ceramic microspheres, effectively overcoming the deficiencies of traditional preparation methods.

[0007] Another objective of this invention is to provide photopolymerizable 3D printed alumina ceramic microspheres and their applications.

[0008] The technical solution adopted in this invention is as follows:

[0009] The method for preparing photopolymerizable 3D printed alumina ceramic microspheres includes the following steps:

[0010] (1) Mix α-Al2O3 powder with anhydrous ethanol and place it in a three-necked flask equipped with a reflux condenser. Heat and reflux the mixture with stirring to carry out azeotropic dehydration and dispersion. Then add ethyl acetate and continue stirring to carry out surface pre-coordination. After that, transfer the mixture to a rotary evaporator and remove the solvent by rotary evaporation to obtain pretreated alumina powder.

[0011] (2) The pretreated alumina powder, reactive diluent, photoinitiator and dispersant are mixed and dispersed by ball milling and vacuum degassing to obtain ceramic slurry; wherein the dispersant is composed of two components.

[0012] (3) Use 3D modeling software to design a sphere model with the required diameter, arrange multiple sphere models on the construction platform through a support structure array, import the slicing software to slice the array model, and generate a print file containing cross-sectional information of each layer.

[0013] (4) Add ceramic slurry to the material tank of the photopolymerization 3D printer. According to the printing file generated in step (3), the printer selectively exposes the slurry through the surface projection light source and cures it layer by layer to carry out photopolymerization 3D printing. Finally, a microbead array blank formed by the support structure and the spherical blank is formed on the construction platform. After printing is completed, the "microbead array blank" is removed from the construction platform and the support structure connecting each spherical blank is removed by physical or chemical means to obtain the spherical blank.

[0014] (5) The spherical blank is sintered to obtain photocurable 3D printed alumina ceramic microspheres.

[0015] The mass ratio of α-Al2O3 powder to anhydrous ethanol is (1:2) to (1:4); the heating and reflux stirring temperature is 70-85℃, and the time is 1-2h.

[0016] The amount of ethyl acetate added is 0.5-1 wt.% of the total amount of α-Al2O3 powder, the surface pre-coordination temperature is 70-85℃, and the time is 0.3-0.8h.

[0017] The rotary evaporation temperature is 60℃ and the pressure is -0.08MPa.

[0018] The volume of the pretreated alumina powder accounts for 55-65% of the total volume of the reactive diluent, photoinitiator, and pretreated alumina powder.

[0019] The active diluent is a mixture of trimethylolpropane triacrylate and tripropylene glycol diacrylate in a volume ratio of (1:2) to (2:1).

[0020] The photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and the amount of photoinitiator is 2-4 wt.% of the total amount of reactive diluent.

[0021] The dispersant is a mixture of KOS110 and BYK-111 in a mass ratio of (1:1) to (3:1), or a mixture of KOS110 and oleic acid in a mass ratio of (2:1) to (4:1). The amount of dispersant used is 2-5 wt. of the total amount of pretreated alumina powder.

[0022] In step (2), the ball milling dispersion uses zirconia balls as the ball milling medium, the ball-to-material ratio is 4:1, the ball milling speed is 300-400 r / min, and the ball milling time is 2-4 h; the vacuum degassing pressure is -0.09 MPa, and the degassing time is 30 min.

[0023] In step (3), the support structure is a thin rod-shaped structure with a diameter smaller than that of the spherical model. The support structure is integrally formed with the spherical blank during printing.

[0024] In step (3), the print file is generated by slicing software, and the slice thickness is 10-50μm.

[0025] In step (4), the supporting structure connecting each spherical blank is removed by physical or chemical means. Preferably, the supporting structure is removed by first soaking the "microbead array blank" in anhydrous ethanol for 5-15 minutes to soften the supporting structure, then gently peeling off the supporting structure with tweezers, and finally rinsing it clean with anhydrous ethanol and letting it air dry naturally.

[0026] In step (4), the photopolymerization 3D printing uses DLP surface projection technology, with an exposure wavelength of 405nm, a single-layer exposure time of 3-10s, and a layer thickness of 10-50μm.

[0027] The sintering is carried out in an air atmosphere, and the specific process includes: first, heating to 500-650℃ at 0.5-2℃ / min and holding for 1-3 hours for degreasing treatment; then heating to 1550-1650℃ at 3-5℃ / min and holding for 1-3 hours for densification sintering; after sintering, cooling to room temperature in the furnace.

[0028] The photocurable 3D printed alumina ceramic microspheres are prepared using the above-mentioned photocurable 3D printed alumina ceramic microspheres preparation method, and have a diameter of 0.3-5 mm and a sphericity ≥0.94.

[0029] The aforementioned photopolymer 3D printed alumina ceramic microspheres are used in grinding and polishing, catalytic carriers, or filtration and separation applications.

[0030] This invention utilizes the strong electronegativity of the carbonyl oxygen atom (C=O) in the ester group (-COO-), enabling it to form hydrogen bonds with hydrogen atoms in the hydroxyl groups on the alumina surface, as well as weak coordination bonds with the small number of exposed metallic aluminum atoms (active sites) on the alumina surface. Under azeotropic reflux conditions at 78°C, the molecular activity of ethyl acetate is enhanced, making it easier to contact the alumina powder surface. The ester group of ethyl acetate combines with the hydroxyl / active aluminum atoms on the alumina surface to form a temporary weak coordination structure. This structure is retained during the subsequent descaling process, thus forming an organic "anchoring point" on the alumina powder surface. Unlike the covalent bond grafting method formed by coupling agents, the binding force of these weakly coordinated organic groups is weaker, but sufficient to achieve the connection between inorganic alumina and organic photosensitive resin. Furthermore, it avoids leaving difficult-to-remove groups like coupling agents, and does not cause an increase in slurry viscosity due to improper dosage.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] (1) The present invention adopts the pretreatment process of "alcohol solvent azeotropic dispersion-surface pre-coordination". By utilizing the azeotropic effect of anhydrous ethanol and water adsorbed on the surface of alumina powder, complete dehydration can be achieved under mild conditions, while avoiding secondary agglomeration that occurs during conventional drying. The ester group of ethyl acetate can form a weak coordination bond with the hydroxyl group on the surface of alumina powder, pre-constructing organic anchoring sites. Powder agglomeration can be inhibited without adding any coupling agent, which greatly reduces the cost of raw materials and simplifies the process.

[0033] (2) By combining the synergistic compounding of dispersants and the optimized selection of active diluents with precise ball milling dispersion process, the present invention can achieve low viscosity control under the condition that the solid volume fraction of the slurry is 55%-65%, and the long-term dispersion stability of the slurry is excellent. At the same time, the slurry has good photocuring responsiveness and can be adapted to DLP surface projection photocuring 3D printing technology to ensure the forming accuracy of the printed blank.

[0034] (3) This invention combines the advantages of array molding of photopolymer 3D printing, which can realize the simultaneous preparation of multiple microbeads and has high production efficiency; through three-dimensional model design, the diameter of microbeads can be precisely controlled to reach the range of 0.3mm-5mm. After the printed blank is sintered, the sphericity of the obtained microbeads is ≥0.94, and the product performance is excellent.

[0035] (4) The preparation process of the present invention is simple and controllable, without the need for complex equipment, and can realize the precise and batch preparation of alumina ceramic microspheres. It effectively solves the problems of low sphericity, poor size controllability and complex process in traditional preparation methods, and has broad industrial application prospects. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the sphere model and supporting structure array arrangement designed in Example 1;

[0037] Figure 2 An optical microscope image of the alumina ceramic microspheres prepared in Example 1. Detailed Implementation

[0038] The present invention will be further described below with reference to the embodiments, but these embodiments do not limit the implementation of the present invention.

[0039] Unless otherwise specified, the raw materials used in the examples are all commercially available and conventional, and the process methods used in the examples are all conventional methods in the art.

[0040] The following is a description of some of the raw materials used in the examples and comparative examples:

[0041] BYK-111, purchased from BYK Chemicals, Germany;

[0042] KOS110, purchased from Guangzhou Kangou Shuang Trading Co., Ltd.

[0043] Example 1

[0044] The method for preparing photopolymerizable 3D printed alumina ceramic microspheres includes the following steps:

[0045] (1) 200g of α-Al2O3 powder (particle size 0.6±0.4μm) was mixed with 600g of anhydrous ethanol and placed in a three-necked flask equipped with a reflux condenser. The mixture was heated to 78℃ and stirred under reflux for 1.5h to carry out azeotropic dehydration dispersion. Then 1g of ethyl acetate was added and stirred at 78℃ for 0.5h to carry out surface pre-coordination. The mixture was then transferred to a rotary evaporator and the solvent was removed by rotary evaporation at 60℃ and -0.08MPa to obtain pretreated alumina powder.

[0046] (2) Mix 30g of reactive diluent (trimethylolpropane triacrylate and dipropylene glycol diacrylate in a volume ratio of 1:2), 0.6g of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 2.92g of dispersant (KOS110 and BYK-111 in a mass ratio of 1:1), place them in a ball mill jar and stir to mix evenly. Then add 146g of pretreated alumina powder (the volume of pretreated alumina powder accounts for 55% of the total volume of reactive diluent, photoinitiator and pretreated alumina powder). Use zirconia balls as the ball milling medium, the ball-to-material ratio is 4:1, and ball mill at 300r / min for 4h. After ball milling, place the slurry in a vacuum degassing chamber and degas under vacuum at -0.09MPa for 30min to obtain a uniform and stable ceramic slurry.

[0047] (3) Create a sphere model with a diameter of 0.5 mm using SolidWorks software. Arrange the sphere model in a 70×40 rectangular array on the construction platform, with a distance of 1.5 mm between the centers of adjacent spheres. Connect the adjacent spheres with cylindrical rods with a diameter of 0.1 mm and a length of 0.2 mm as a support structure (see the schematic diagram of the sphere model and support structure array arrangement). Figure 1 (As shown). Import the slicing software ChiTuBox, slice the array model, with a slice thickness of 30μm, and generate a print file containing cross-sectional information for each layer;

[0048] (4) Add the ceramic slurry to the material tank of the DLP photopolymerization 3D printer, import the printing file generated in step (3), set the exposure wavelength to 405nm, the single-layer exposure time to 3s, and the layer thickness to 30μm. Start printing, and the printer selectively exposes the slurry through the surface projection light source, solidifies the slurry layer by layer, and performs photopolymerization 3D printing. Finally, a microbead array blank formed by the support structure and the spherical blank is formed on the construction platform.

[0049] After printing is completed, the "microbead array preform" is removed from the construction platform and soaked in anhydrous ethanol for 5 minutes to soften the support structure. Then, the support structure is gently peeled off with tweezers. Finally, it is rinsed clean with anhydrous ethanol and air-dried to obtain a spherical preform.

[0050] (5) The spherical blank is placed in a box-type resistance furnace for sintering. The sintering is carried out in an air atmosphere. The specific process is as follows: first, the temperature is raised to 600℃ at 1℃ / min and held for 2h to completely remove the organic components; then, the temperature is raised to 1600℃ at 5℃ / min and held for 2h; after sintering, the blank is cooled to room temperature with the furnace to obtain photocurable 3D printed alumina ceramic microspheres with a diameter of 0.32mm.

[0051] Figure 2The image shown is an optical microscope image of the alumina ceramic microspheres prepared in Example 1. It can be seen that the prepared alumina ceramic microspheres have high sphericity.

[0052] Example 2

[0053] The method for preparing photopolymerizable 3D printed alumina ceramic microspheres includes the following steps:

[0054] (1) 200g of α-Al2O3 powder (particle size 0.6±0.4μm) was mixed with 500g of anhydrous ethanol and placed in a three-necked flask equipped with a reflux condenser. The mixture was heated to 75℃ and stirred under reflux for 1.8h to carry out azeotropic dehydration dispersion. Then 1.6g of ethyl acetate was added and stirred at 75℃ for 0.6h to carry out surface pre-coordination. The mixture was then transferred to a rotary evaporator and the solvent was removed by rotary evaporation at 60℃ and -0.08MPa to obtain pretreated alumina powder.

[0055] (2) Mix 30g of reactive diluent (trimethylolpropane triacrylate and dipropylene glycol diacrylate in a volume ratio of 1:1), 0.9g of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 5.4g of dispersant (KOS110 and BYK-111 in a mass ratio of 2:1), place them in a ball mill jar and stir to mix evenly. Then add 180.8g of pretreated alumina powder (the volume of pretreated alumina powder accounts for 60% of the total volume of reactive diluent, photoinitiator and pretreated alumina powder). Use zirconia balls as the ball milling medium, the ball-to-material ratio is 4:1, and ball mill at 300r / min for 4h. After ball milling, place the slurry in a vacuum degassing chamber and degas under vacuum at -0.09MPa for 30min to obtain a uniform and stable ceramic slurry.

[0056] (3) Create a sphere model with a diameter of 2mm using SolidWorks software. Arrange the sphere model in a 50×30 rectangular array on the construction platform, with a distance of 3mm between the centers of adjacent spheres. Connect the adjacent spheres with cylindrical rods with a diameter of 0.15mm and a length of 0.3mm as the support structure. Import the slicing software ChiTuBox, slice the array model, and slice the layer with a thickness of 20μm to generate a print file containing cross-sectional information of each layer.

[0057] (4) Add the ceramic slurry to the material tank of the DLP photopolymerization 3D printer, import the printing file generated in step (3), set the exposure wavelength to 405nm, the single-layer exposure time to 6s, and the layer thickness to 20μm. Start printing, and the printer selectively exposes the slurry through the surface projection light source, solidifies the slurry layer by layer, and performs photopolymerization 3D printing. Finally, a microbead array blank formed by the support structure and the spherical blank is formed on the construction platform.

[0058] After printing is completed, the "microbead array preform" is removed from the construction platform and soaked in anhydrous ethanol for 10 minutes to soften the support structure. Then, the support structure is gently peeled off with tweezers. Finally, it is rinsed clean with anhydrous ethanol and air-dried to obtain a spherical preform.

[0059] (5) The spherical blank is placed in a box-type resistance furnace for sintering. The sintering is carried out in an air atmosphere. The specific process is as follows: first, the temperature is raised to 550℃ at 0.8℃ / min and held for 2.5h to completely remove organic components; then, the temperature is raised to 1580℃ at 4℃ / min and held for 2.5h; after sintering, the blank is cooled to room temperature with the furnace to obtain photocurable 3D printed alumina ceramic microspheres with a diameter of 1.6mm.

[0060] Example 3

[0061] The method for preparing photopolymerizable 3D printed alumina ceramic microspheres includes the following steps:

[0062] (1) 200g of α-Al2O3 powder (particle size 0.6±0.4μm) was mixed with 600g of anhydrous ethanol and placed in a three-necked flask equipped with a reflux condenser. The mixture was heated to 78℃ and stirred under reflux for 1.5h to carry out azeotropic dehydration dispersion. Then 2.0g of ethyl acetate was added and stirred at 78℃ for 0.5h to carry out surface pre-coordination. The mixture was then transferred to a rotary evaporator and the solvent was removed by rotary evaporation at 60℃ and -0.08MPa to obtain pretreated alumina powder.

[0063] (2) Mix 30g of reactive diluent (trimethylolpropane triacrylate and dipropylene glycol diacrylate in a volume ratio of 2:1), 1.2g of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 11.3g of dispersant (KOS110 and BYK-111 in a mass ratio of 3:1), place them in a ball mill jar and stir to mix evenly. Then add 226g of pretreated alumina powder (the volume of pretreated alumina powder accounts for 65% of the total volume of reactive diluent, photoinitiator and pretreated alumina powder), use zirconia balls as the ball milling medium, the ball-to-material ratio is 4:1, and ball mill at 300r / min for 4h. After ball milling, place the slurry in a vacuum degassing box and degas under vacuum at -0.09MPa for 30min to obtain a uniform and stable ceramic slurry.

[0064] (3) Create a sphere model with a diameter of 4mm using SolidWorks software. Arrange the sphere model in a 30×20 rectangular array on the construction platform, with a spacing of 6mm between adjacent sphere centers. Connect the adjacent spheres using cylindrical rods with a diameter of 0.2mm and a length of 0.4mm as a support structure. Import the slicing software ChiTuBox and slice the array model. The slice layer thickness is 40μm. Generate a print file containing cross-sectional information for each layer.

[0065] (4) Add the ceramic slurry to the material tank of the DLP photopolymerization 3D printer, import the printing file generated in step (3), set the exposure wavelength to 405nm, the single-layer exposure time to 3s, and the layer thickness to 40μm. Start printing, and the printer selectively exposes the slurry through the surface projection light source, solidifies the slurry layer by layer, and performs photopolymerization 3D printing. Finally, a microbead array blank formed by the support structure and the spherical blank is formed on the construction platform.

[0066] After printing is completed, the "microbead array preform" is removed from the construction platform and soaked in anhydrous ethanol for 15 minutes to soften the support structure. Then, the support structure is gently peeled off with tweezers. Finally, it is rinsed clean with anhydrous ethanol and air-dried to obtain a spherical preform.

[0067] (5) The spherical blank is placed in a box-type resistance furnace for sintering. The sintering is carried out in an air atmosphere. The specific process is as follows: first, the temperature is raised to 650℃ at 2℃ / min and held for 1h to completely remove the organic components; then, the temperature is raised to 1650℃ at 5℃ / min and held for 1h; after sintering, the blank is cooled to room temperature with the furnace to obtain photocurable 3D printed alumina ceramic microspheres with a diameter of 3.8mm.

[0068] Comparative Example 1

[0069] The difference from Example 1 is that ethyl acetate was not added in step (1). Instead, α-Al2O3 powder was azeotropically dehydrated and dispersed with anhydrous ethanol and then directly dried to obtain pretreated alumina powder. The other conditions were the same as in Example 1.

[0070] Comparative Example 2

[0071] The difference from Example 1 is that in step (1), α-Al2O3 powder is mixed with anhydrous ethanol and ethyl acetate and stirred at room temperature for 1.5 h. Then the mixture is transferred to a rotary evaporator and the solvent is removed by rotary evaporation at 60 °C and -0.08 MPa to obtain pretreated alumina powder. The other conditions are the same as in Example 1.

[0072] Comparative Example 3

[0073] The difference from Example 1 is that in step (2), only KOS110 (2.92g) is used as the dispersant, and it is not compounded with BYK-111. The other conditions are the same as in Example 1.

[0074] Comparative Example 4

[0075] The difference from Example 1 is that in step (1), silane coupling agent KH-550 is used instead of ethyl acetate (the amount added is 0.5 wt.% of the total amount of α-Al2O3 powder). α-Al2O3 powder is mixed with anhydrous ethanol and KH-550 and stirred at room temperature for 2 hours. Then the mixture is transferred to a rotary evaporator and the solvent is removed by rotary evaporation at 60°C and -0.08 MPa to obtain pretreated alumina powder. The other conditions are the same as in Example 1.

[0076] The viscosity of the ceramic slurries prepared in the examples and comparative examples was tested using a rotational viscometer. The test results are shown in Table 1.

[0077] The performance of the alumina ceramic microspheres prepared in the examples and comparative examples was tested, and the test methods are as follows:

[0078] Solid content: The percentage of the volume of pretreated alumina powder relative to the total volume of reactive diluent, photoinitiator, and pretreated alumina powder;

[0079] Density: Tested using Archimedes' displacement method, in accordance with GB / T 25995-2010;

[0080] Sphericity: According to GB / T 19077-2016, sphericity is calculated by laser particle size analyzer combined with image analysis software. Sphericity = actual minimum circumscribed sphere diameter / actual maximum circumscribed sphere diameter.

[0081] Vickers hardness: Refer to GB / T 16534-2009, use a Vickers hardness tester, test force 10N, holding time 10s;

[0082] Toughness: Tested in accordance with GB / T 23806-2009.

[0083] The test results are shown in Table 1.

[0084] Table 1 Performance Test Results

[0085]

[0086] As can be seen from the data in Table 1, the ceramic slurries of Examples 1-3 maintained a low viscosity (3.2-6.5 Pa) even under high solids content (55%-65% v / v) conditions. The results (s) were far superior to those of the comparative studies (7.6-10.3 Pa). (s) This illustrates that the "alcohol solvent azeotropic dispersion-surface pre-coordination" pretreatment process and the composite dispersant compounding scheme of the present invention work synergistically to effectively improve the dispersion stability of the slurry;

[0087] The sphericity of the products in the examples is ≥0.94, which is significantly higher than that of the comparative examples (0.82-0.88). This demonstrates the synergistic advantages of DLP photopolymerization 3D printing array forming and optimized process, and solves the problem of insufficient sphericity in traditional methods.

[0088] The density (94%-96%), Vickers hardness (19.5-20.8 GPa), and toughness (3.8-4.3 MPa) of the examples are as follows. In terms of m¹ / ², it is superior to the comparative example. In the special process scenario of photopolymer 3D printing, it achieves a three-dimensional balance of "process adaptability + mechanical properties + core functions (sphericity, size controllability)" and has better overall practicality.

[0089] Comparative Example 1 (without ethyl acetate) and Comparative Example 2 (without heating pretreatment) suffered from severe powder agglomeration, resulting in a surge in slurry viscosity and a decline in product performance. Comparative Example 3 (single dispersant) could not achieve low viscosity control under high solid content. Although Comparative Example 4 (silane coupling agent) had a certain modification effect, its adaptability was insufficient, and its performance was still inferior to that of the examples.

Claims

1. A method for preparing photocured 3D printed alumina ceramic microbeads, characterized in that, The method comprises the following steps: (1) mixing α-Al2O3 powder with anhydrous ethanol, and carrying out co-boiling dehydration dispersion by heating and refluxing and stirring; then adding ethyl acetate to carry out surface pre-coordination; and then removing the solvent to obtain pre-processed alumina powder; (2) mixing the pre-processed alumina powder, active diluent, photoinitiator and dispersant, and carrying out ball milling dispersion and vacuum degassing treatment to obtain ceramic slurry; wherein the active diluent is a mixture of trimethylolpropane triacrylate and tripropyleneglycol diacrylate, and the volume ratio is (1:2)-(2:1); the dispersant is a compound of KOS110 and BYK-111 with a mass ratio of (1:1)-(3:1), or a compound of KOS110 and oleic acid with a mass ratio of (2:1)-(4:1); (3) designing a spherical model by using a three-dimensional modeling software, arraying a plurality of spherical models through a support structure, importing a slicing software to slice, and generating a printing file; (4) adding the ceramic slurry into a photocuring 3D printer, photocuring 3D printing according to the printing file to form a microbead array blank integrally formed by the support structure and the spherical blank; and after printing is completed, removing the support structure to obtain the spherical blank; (5) sintering the spherical blank to obtain the photocuring 3D printed alumina ceramic microbead.

2. The method of claim 1, wherein the photocured 3D printed alumina ceramic microbeads are characterized by, The mass ratio of the α-Al2O3 powder to the anhydrous ethanol is (1:2)-(1:4); the temperature of heating and refluxing and stirring is 70-85℃, and the time is 1-2h.

3. The method of claim 1, wherein the photocured 3D printed alumina ceramic microbeads are characterized by, The adding amount of the ethyl acetate is 0.5-1wt.% of the total amount of the α-Al2O3 powder, the surface pre-coordination temperature is 70-85℃, and the time is 0.3-0.8h.

4. The method of claim 1, wherein the photocured 3D printed alumina ceramic microbeads are characterized by, The volume of the pre-processed alumina powder accounts for 55-65% of the total volume of the active diluent, the photoinitiator and the pre-processed alumina powder.

5. The method of claim 1, wherein the photocured 3D printed alumina ceramic microbeads are characterized by, The photoinitiator is 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide, and the amount of the photoinitiator is 2-4wt.% of the total amount of the active diluent.

6. The method of claim 1, wherein the photocured 3D printed alumina ceramic microbeads are characterized by, The amount of the dispersant is 2-5wt.% of the total amount of the pre-processed alumina powder.

7. The method of claim 1, wherein the photocured 3D printed alumina ceramic microbeads are characterized by, In the step (4), the photocuring 3D printing adopts DLP surface projection technology, the exposure wavelength is 405nm, the single layer exposure time is 3-10s, and the layer thickness is 10-50μm.

8. The method of claim 1, wherein the photocured 3D printed alumina ceramic microbeads are characterized by, The sintering is carried out in an air atmosphere, and the specific process comprises: first, increasing the temperature to 500-650℃ at a rate of 0.5-2℃ / min and keeping the temperature for 1-3h, and then increasing the temperature to 1550-1650℃ at a rate of 3-5℃ / min and keeping the temperature for 1-3h.

9. A photocured 3D printed alumina ceramic microbead, characterized in that, The photocuring 3D printed alumina ceramic microbead prepared by the method has a diameter of 0.3-5mm and a sphericity of ≥0.

94.

10. Use of the photocured 3D printed alumina ceramic microbeads according to claim 9, characterized in that, The photocuring 3D printed alumina ceramic microbead is used in the fields of grinding and polishing, catalytic carrier or filtration and separation.

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