Photocuring 3D printing aluminum-based ceramic core based on core-shell structure mineralizer modification and preparation method

Abstract

The invention discloses a core-shell structure mineralizer modification-based photocuring 3D printing aluminum-based ceramic core and a preparation method thereof. The aluminum-based ceramic core comprises the following substances in percentage by weight: 65-75% of aluminum-based ceramic powder, 5-15% of a core-shell structure mineralizer component and 15-25% of a photosensitive resin component. The preparation method comprises the following steps: preparing aluminum-based ceramic core slurry, and vacuumizing the aluminum-based ceramic core slurry; injecting the aluminum-based ceramic core slurry into a trough of 3D printing equipment, and printing an aluminum-based ceramic core blank; the aluminum-based ceramic core green body is subjected to ultrasonic cleaning and drying treatment; and the aluminum-based ceramic core blank is subjected to degreasing treatment and sintering treatment, and the photocuring 3D printing aluminum-based ceramic core based on core-shell structure mineralizer modification is prepared. According to the method, the sintering temperature of the 3D printing aluminum-based ceramic core blank can be effectively adjusted, generation of interlayer cracks in the degreasing and sintering process is reduced, and the aluminum-based ceramic core with excellent comprehensive performance is obtained.

Description

Photopolymerization 3D Printing Aluminum-based Ceramic Core Based on Core-Shell Structure Mineralizer Modification and its Preparation Method Technical Field

[0001] This invention belongs to the field of ceramic core material design and preparation technology, specifically relating to a photopolymerization 3D printing aluminum-based ceramic core based on core-shell structure mineralizer modification and its preparation method. Background Technology

[0002] With the ever-increasing performance requirements of high-temperature components in the modern aerospace field, aluminum-based ceramic cores play a crucial role in investment casting (especially in the manufacture of high-temperature alloy blades) due to their excellent high-temperature stability, creep resistance, and chemical inertness. However, traditional manufacturing processes for aluminum-based ceramic cores (such as hot press molding) have limitations such as high mold costs, long development cycles, and difficulty in forming complex and delicate internal cavity structures. In recent years, photopolymerization 3D printing technology has provided an advanced technical path for the rapid, flexible, and precise forming of ceramic cores. This technology can directly form ceramic blanks with complex flow channels, air-cooling cavities, and other intricate structures based on three-dimensional digital models, greatly simplifying the process and significantly shortening the product development cycle.

[0003] In terms of material systems, existing aluminum-based ceramic core slurries suitable for photopolymerization 3D printing typically consist of alumina ceramic powder, photosensitive resin systems, and necessary additives. However, due to the strong ionic bonds and numerous cationic charges of alumina, its low proton diffusion coefficient and high lattice energy result in sintering temperatures exceeding 1700℃ for alumina ceramics. This high-temperature process window presents the following technical challenges: high-temperature sintering causes rapid alumina grain growth, leading to the rapid aggregation of micropores within the ceramic, resulting in uncontrolled microstructure and difficulty in achieving the required density and mechanical properties for high-performance cores; the high-temperature sintering process exacerbates the risk of deformation and cracking caused by uneven shrinkage, severely affecting the dimensional accuracy and yield of the core; and the higher sintering temperature also significantly increases energy consumption and production costs.

[0004] To promote densification and reduce sintering temperature, existing technologies typically involve directly adding a certain proportion of mineralizer to alumina ceramic powder. However, this simple method of adding mineralizer still faces significant technical bottlenecks in material design and process implementation when applied to photopolymerization 3D printing: Firstly, the mineralizer dispersion is poor. In traditional photopolymerization slurry preparation processes, mineralizer powder is usually physically mixed with alumina main phase powder. Due to differences in particle size, density, and surface chemical properties between the mineralizer and alumina, sedimentation, agglomeration, or phase separation easily occur during slurry preparation, storage, and printing. This uneven distribution directly leads to local enrichment or depletion of mineralizer within the printed blank. In subsequent debinding and sintering processes, this can easily cause significant differences in local sintering rates, uneven stress distribution, and inconsistent shrinkage, resulting in defects such as warping, cracking, and deformation of the core product, making it difficult to guarantee dimensional accuracy and shape fidelity.

[0005] Secondly, the sintering behavior and core performance are uncontrollable. The mineralizer, which is simply physically mixed, comes into contact with the surface of alumina particles and reacts rapidly in the early stage of sintering. This premature and violent reaction can lead to the premature formation, excessive seepage or volatilization of local liquid phases, which not only reduces the effective utilization rate of the mineralizer, but may also cause problems such as uncontrolled grain growth, uneven porosity, and disordered distribution of the second phase. Ultimately, this leads to damage to the performance of the ceramic core and poor performance stability between batches.

[0006] Third, mineralizers have limited functionality and lack synergistic design and multifunctionality. Existing mineralizers mainly focus on reducing sintering temperature, and their introduction methods do not fully consider the deep integration with the characteristics of photocuring processes and the multi-dimensional performance requirements of the final ceramic core. As an independent dispersed phase, mineralizers cannot simultaneously play multiple roles such as enhancing slurry rheology, improving printing efficiency, and guiding microstructure evolution.

[0007] In summary, while existing photopolymerization 3D printing technologies for aluminum-based ceramic cores have achieved some success in reducing sintering temperatures by introducing mineralizers, the introduction methods remain at the simple physical blending stage. This fails to address core issues such as uniform dispersion and precise controllability of sintering behavior, severely hindering the reliable manufacturing of high-quality, high-precision, and high-performance complex-structure aluminum-based ceramic cores. Therefore, there is an urgent need to develop a photopolymerization 3D printing aluminum-based ceramic core and its preparation method based on core-shell structure mineralizer modification. This would enable mineralizer modification to be compatible with photopolymerization 3D printing processes, allowing for precise control of the sintering process and ultimately producing high-performance aluminum-based ceramic cores. Summary of the Invention

[0008] To address the problems existing in the prior art, this invention provides a photopolymerization 3D printing aluminum-based ceramic core based on a core-shell structure mineralizer modification. The mass percentage of each substance in the aluminum-based ceramic core is as follows: 65-75 wt% aluminum-based ceramic powder, 5-15 wt% core-shell structure mineralizer component, and 15-25 wt% photosensitive resin component, with the sum of the contents of all substances being 100 wt%. Each substance in the core-shell structure mineralizer component is a core-shell structure powder.

[0009] Preferably, the aluminum-based ceramic powder is fused alumina powder, which includes three particle size ranges. The mass percentage of each particle size range is as follows: 10μm ≤ particle size ≤ 30μm accounts for 42-55 wt%, 5μm ≤ particle size < 10μm accounts for 25-38 wt%, and 1μm ≤ particle size < 5μm accounts for 15-25 wt%. In this invention, the fused alumina powder is a corundum refractory material smelted from industrial alumina or calcined alumina, and is the main matrix material for investment casting.

[0010] In any of the above embodiments, it is preferred that the mass percentage of each substance in the core-shell structured mineralizer component is as follows: 5-10 wt% core-shell structured magnesium oxide powder, 18-28 wt% core-shell structured silica powder, 8-15 wt% core-shell structured titanium oxide powder, 8-15 wt% core-shell structured zirconium silicate powder, 15-18 wt% core-shell structured mullite powder, 15-18 wt% core-shell structured sodium zirconium phosphate powder, 4-8 wt% core-shell structured cordierite powder, and 4-8 wt% core-shell structured diatomaceous earth powder, with the sum of the contents of each substance being 100 wt%.

[0011] Preferably, in any of the above embodiments, the core-shell structured magnesium oxide powder, the core-shell structured silica powder, and the core-shell structured titanium oxide powder are respectively polystyrene-coated magnesium oxide powder, polystyrene-coated silica powder, and polystyrene-coated titanium oxide powder. The magnesium oxide powder, silica powder, and titanium oxide powder each include three particle size ranges, and the mass percentage of each particle size range in the magnesium oxide powder, silica powder, and titanium oxide powder is as follows: 5μm ≤ particle size ≤ 20μm accounts for 42-52wt%, 1μm ≤ particle size < 5μm accounts for 28-40wt%, and 0.1μm ≤ particle size < 1μm accounts for 15-25wt%.

[0012] The core-shell structured zirconium silicate powder and the core-shell structured mullite powder are respectively polystyrene-coated zirconium silicate powder and polystyrene-coated mullite powder. Both the zirconium silicate powder and the mullite powder include two particle size ranges. The mass percentage of each particle size range in the zirconium silicate powder and the mullite powder is 52-68 wt% for particles with a particle size of 8 μm ≤ 20 μm and 32-48 wt% for particles with a particle size of 1 μm ≤ < 8 μm.

[0013] The core-shell structured sodium zirconium phosphate powder and the core-shell structured cordierite powder are respectively polystyrene-coated sodium zirconium phosphate powder and polystyrene-coated cordierite powder. Both the sodium zirconium phosphate powder and the cordierite powder include three particle size ranges. The mass percentage of each particle size range in the sodium zirconium phosphate powder and the cordierite powder is as follows: 10μm≤particle size≤35μm accounts for 28-42wt%, 5μm≤particle size<10μm accounts for 40-50wt%, and 1μm≤particle size<5μm accounts for 15-25wt%.

[0014] The core-shell structured diatomaceous earth powder is polystyrene-coated diatomaceous earth. The diatomaceous earth includes two particle size ranges, with each particle size range accounting for 55-65 wt% of the diatomaceous earth by mass: 5 μm ≤ particle size ≤ 18 μm accounts for 55-65 wt%, and 1 μm ≤ particle size < 5 μm accounts for 35-45 wt%.

[0015] In any of the above embodiments, it is preferred that the mass percentage of each substance in the photosensitive resin component is 1-5 wt% for photoinitiator, 5-10 wt% for dispersant, and 85-90 wt% for crosslinking aid, and the sum of the contents of each substance is 100 wt%.

[0016] In any of the above embodiments, preferably, the photoinitiator is 1-hydroxycyclohexylphenyl ketone and / or trimethylbenzoyl-diphenylphosphine oxide; the dispersant is any one or more of BYK-111, BYK-9076, and KOS-110; and the mass percentage of each substance in the crosslinking aid is 42-55 wt% of 1,6-hexanediol diacrylate, 22-35 wt% of trimethylolpropane triacrylate, 10-14 wt% of isobornyl acrylate, and 10-14 wt% of isobornyl methacrylate.

[0017] In this invention, BYK-111 and BYK-9076 are different types of dispersants from BYK (Germany), and KOS-110 is a dispersant from KOC (Korea). Among the crosslinking aids, isobornyl acrylate, isobornyl methacrylate, and 1,6-hexanediol diacrylate have fewer functional groups, which can give the ceramic slurry good fluidity; trimethylolpropane triacrylate is a trifunctional organic monomer that can effectively accelerate photopolymerization and improve printing effect.

[0018] This invention also provides a method for preparing a photopolymerizable 3D printed aluminum-based ceramic core based on a core-shell structure mineralizer modification. The preparation method includes the following steps in sequence: Step 1: Preparing an aluminum-based ceramic core slurry according to the designed material ratio and process parameters; Step 2: Placing the container containing the aluminum-based ceramic core slurry in a vacuum device for vacuum treatment to remove air bubbles inside the slurry; Step 3: Injecting the aluminum-based ceramic core slurry into the material tank of the 3D printing equipment and printing the aluminum-based ceramic core blank according to the designed core structure; Step 4: The aluminum-based ceramic core preform is ultrasonically cleaned in an ultrasonic cleaner to remove uncured resin and surface residues. Then, it is transferred to an oven for drying to completely remove photopolymer residues and improve surface smoothness. In step five, the aluminum-based ceramic core preform is degreased in a box-type muffle furnace to remove organic matter from the preform. In step six, the aluminum-based ceramic core preform is sintered in a sintering furnace to promote densification of the preform. After sintering, a photopolymerized 3D printed aluminum-based ceramic core modified with a core-shell structure mineralizer is obtained.

[0019] Preferably, in step one, the preparation of the aluminum-based ceramic core slurry includes the following steps in sequence: Step 1.1: Prepare core-shell structured magnesium oxide powder, core-shell structured silica powder, core-shell structured titanium oxide powder, core-shell structured zirconium silicate powder, core-shell structured mullite powder, core-shell structured sodium zirconium phosphate powder, core-shell structured cordierite powder, and core-shell structured diatomaceous earth powder according to the designed process parameters. Then, put the prepared core-shell structured powders into a V-type mixer and mix them evenly at room temperature at a mixing speed of 300-600 rpm. Step 1.2: Place the aluminum-based ceramic powder and the core-shell structured mineralizer component into a mixer and stir at room temperature at a speed of 300-600 rpm for 1-2 hours to ensure uniform mixing of all substances. Step 1.3: Place the photoinitiator, dispersant, and crosslinking aid into a mixer and continue stirring at room temperature at a speed of 300-600 rpm for 3-6 hours to ensure uniform mixing of all substances, thus obtaining the aluminum-based ceramic core slurry.

[0020] In any of the above schemes, it is preferred that, in step 1.1, the preparation methods of the core-shell structured magnesium oxide powder, core-shell structured silica powder, core-shell structured titanium oxide powder, core-shell structured zirconium silicate powder, core-shell structured mullite powder, core-shell structured sodium zirconium phosphate powder, core-shell structured cordierite powder, and core-shell structured diatomaceous earth powder are the same. Among the various core-shell structured powders prepared, magnesium oxide powder, silica powder, titanium oxide powder, zirconium silicate powder, mullite powder, sodium zirconium phosphate powder, cordierite powder, and diatomaceous earth are the core materials of their respective core-shell structured powders. The specific preparation methods include the following steps in sequence: Step (1): Put the core material into a beaker containing deionized water, and then put the beaker into an ultrasonic machine for ultrasonic treatment. Ultrasonic dispersion was used to obtain a nuclear material mixture. The mass ratio of nuclear material to deionized water was 1:30-40. The ultrasonic frequency was 15-25 kHz and the ultrasonic time was 10-15 min. Step (2): The nuclear material mixture in the beaker was transferred to a centrifuge tube and then placed in a benchtop high-speed centrifuge for centrifugation. The centrifugation speed was 7000-8000 rpm and the centrifugation time was 10-15 min. After centrifugation, the mixture was allowed to stand to precipitate the nuclear material and the supernatant was removed. Step (3): Steps (1) to (2) were repeated twice to obtain the pretreated nuclear material. Step (4): The pretreated nuclear material was placed in a mixed solution of ethanol and deionized water and stirred evenly at room temperature. Premixed slurry A is obtained, with the mass ratio of nuclear material to mixed solution being 1:45-55, and the mass ratio of ethanol to deionized water being 8-12:1. The stirring speed is 300-500 rpm, and the stirring time is 20-40 min. Step (5): Styrene monomer and benzoyl peroxide are mixed evenly at room temperature to obtain a mixed solution of the two, with the mass ratio of styrene monomer to benzoyl peroxide being 14-18:1. The mixed solution of the two is slowly added to premixed slurry A and stirred evenly at room temperature to obtain premixed slurry B, with the mass ratio of the mixed solution of the two to premixed slurry A being 4-6:1. The stirring speed is 300-500 rpm, and the stirring time is 20-30 min. Step (6): The container containing premixed slurry B is placed in a water bath and heated and stirred to coat the surface of the core material with organic matter, resulting in a mixed core material slurry. The heating temperature is 70-80℃, the stirring speed is 500-600rpm, and the stirring time is 4-5h. Step (7): The mixed core material slurry is placed in a drying oven for drying to remove ethanol and deionized water, resulting in a blocky core material solid. The drying temperature is 80-100℃, and the drying time is 6-12h. Step (8): The blocky core material solid is washed and filtered three times in ethanol, and then placed in a drying oven for drying to obtain polystyrene-coated core material. The drying temperature is 50-80℃, and the drying time is 6-12h.

[0021] In any of the above schemes, it is preferred that, in step two, the aluminum-based ceramic core slurry is subjected to vacuum treatment with a vacuum degree of -0.06 to -0.07 MPa and a holding time of 5-10 min.

[0022] In any of the above schemes, it is preferred that, in step three, during the printing of the aluminum-based ceramic core preform, the main process parameters involved are: a cured layer thickness of 50-100 μm, an ultraviolet light wavelength of 300-450 nm, an exposure time of 3-10 s, and an exposure power of 10-30 mW / cm². 2 .

[0023] In any of the above schemes, it is preferred that, in step four, the cleaning agent used for ultrasonic cleaning is any one of ethanol, acetone, and isopropanol, the ultrasonic cleaning frequency is 80-100kHz, the ultrasonic cleaning time is 3-5min, the drying temperature is 100-110℃, and the drying time is 8-10min.

[0024] In any of the above schemes, the preferred method is that, in step five, the degreasing process of the aluminum-based ceramic core blank is as follows: first, the aluminum-based ceramic core blank is embedded in a sagger filled with kaolin, and then the sagger is placed in a box-type muffle furnace; under an air atmosphere, the temperature is increased from room temperature to 200℃ at a heating rate of 0.1-0.5℃ / min and held for 1-2 hours; the temperature is further increased to 320℃ at a heating rate of 0.1-0.5℃ / min and held for 1-2 hours; the temperature is further increased to 460℃ at a heating rate of 0.1-0.5℃ / min and held for 1-2 hours; the temperature is further increased to 600℃ at a heating rate of 0.1-0.5℃ / min and held for 1-2 hours, and then cooled to room temperature with the furnace.

[0025] In any of the above schemes, the preferred method is that, in step six, the sintering process of the aluminum-based ceramic core blank is as follows: a sagger containing kaolin filler and the aluminum-based ceramic core blank is placed in a sintering furnace, and under an air atmosphere, the temperature is raised from room temperature to 1100℃ at a heating rate of 3-5℃ / min and held for 1-1.5h; the temperature is then raised to 1280-1350℃ at a heating rate of 2-3℃ / min and held for 4-6h; and then the temperature is lowered to 900℃ at a cooling rate of 1-4℃ / min and cooled to room temperature with the furnace.

[0026] The vacuum equipment, 3D printing equipment, ultrasonic cleaner, oven, drying oven, box-type muffle furnace, sintering furnace, benchtop high-speed centrifuge, V-type mixer, and agitator used in this invention are all traditional equipment, and there are no special requirements for their structure or model. The 3D printing process for aluminum-based ceramic core blanks is also a traditional process, and there are no special requirements for the process flow, as long as the aforementioned main process parameters meet the requirements of this invention.

[0027] In the entire preparation process of the aluminum-based ceramic core, the material selection and proportion of the core-shell structure mineralizer components, the gradation and content of the core material in various core-shell structure powders, and the preparation process and process parameters of various core-shell structure powders are all very critical. These parameters need to work together to achieve the technical effect expected by this invention.

[0028] This invention innovatively introduces a core-shell structured mineralizer component, achieving low-temperature sintering and improved overall performance of aluminum-based ceramic cores. During sintering, the outer shell of the core-shell powder preferentially forms a uniform liquid phase, effectively driving the rearrangement and densification of ceramic particles, thereby significantly reducing the overall sintering temperature. The core of the core-shell powder, as a high-temperature stable phase, inhibits abnormal grain growth while also playing a role in structural reinforcement and crack toughening. This mechanism not only fundamentally alleviates the deformation and cracking problems caused by traditional high-temperature sintering, ensuring that the 3D-printed aluminum-based ceramic core blank maintains excellent shape integrity and dimensional stability throughout the debinding and sintering process, but also improves the overall efficiency from 3D printing to post-processing by reducing the process temperature and shortening the production cycle. Ultimately, it achieves a breakthrough in aluminum-based ceramic core preparation technology in terms of process reliability, structural accuracy, and overall performance.

[0029] The present invention is based on the photopolymerization 3D printing aluminum-based ceramic core and preparation method modified by core-shell structure mineralizer, which has the following beneficial effects: (1) The present invention constructs a core-shell structure mineralizer component, so that the shell forms a stable interface in the slurry system, effectively suppressing the agglomeration and phase separation caused by the physical difference between it and the matrix material, realizing the uniform dispersion of mineralizer powder, avoiding local reaction too fast or insufficient, significantly reducing stress concentration caused by local density difference and inconsistent shrinkage during degreasing and sintering, fundamentally suppressing the problems of warping, cracking and deformation of ceramic core in the later heat treatment, and ensuring that the ceramic core maintains excellent shape integrity and dimensional stability.

[0030] (2) The core-shell structure mineralizer component of the present invention has an outer shell that can adjust the contact timing and reaction rate between the mineralizer and the matrix particles, avoid premature or excessive local liquid phase generation, ensure that the liquid phase is uniformly formed in the appropriate temperature range and continuously promotes densification. This not only significantly improves the utilization efficiency of the mineralizer, but also promotes uniform grain growth and controllable pore distribution, and finally obtains an aluminum-based ceramic core with uniform microstructure, excellent mechanical properties and high batch consistency.

[0031] (3) The core-shell structure mineralizer component design of the present invention breaks through the functional limitation of traditional mineralizers that only reduce sintering temperature. Through material and structural design, it can play multiple roles at the same time: the outer shell can regulate the rheological properties of the slurry and improve printing efficiency; the core, as a high-temperature stable phase, can inhibit abnormal grain growth during sintering and can also act as a reinforcing phase to improve the toughness of the core; the overall structure can guide the densification process, microstructure evolution and final performance during sintering, thereby ensuring low-temperature sintering while synergistically improving the dimensional accuracy, structural integrity and comprehensive performance of the core.

[0032] (4) The aluminum-based ceramic core (after sintering) prepared by the present invention has a roughness of 2.1-3.5 μm, a sintering shrinkage rate of 1.7-3.4% in the printing direction, a porosity of 30-45%, a room temperature bending strength of 18-22 MPa, a high temperature bending strength of 18-25 MPa, and a deflection of 0.5-1.2 mm.

[0033] (5) The present invention can effectively adjust the sintering temperature of the photopolymer 3D printed aluminum-based ceramic core blank, reduce the generation of interlayer cracks during degreasing and sintering, obtain aluminum-based ceramic core with excellent comprehensive performance, and promote the application of 3D printing technology in the field of ceramic core precision casting. Attached Figure Description

[0034] Figure 1 is a microstructure of the core-shell structure powder (core-shell structure titanium dioxide powder) prepared according to a preferred embodiment of the photopolymerization 3D printing aluminum-based ceramic core modified with a core-shell structure mineralizer and the preparation method of the present invention; Figure 2 is a physical image of the aluminum-based ceramic core slurry prepared in the embodiment shown in Figure 1; Figure 3 is a physical image of the aluminum-based ceramic sample prepared in the embodiment shown in Figure 1; Figure 4 is a partial physical image of the aluminum-based ceramic core prepared in the embodiment shown in Figure 1; Figure 5 is a microstructure of the aluminum-based ceramic core prepared in the embodiment shown in Figure 1 (showing pores); Figure 6 is a microstructure of the aluminum-based ceramic core prepared in the embodiment shown in Figure 1 (showing the sintering neck). Detailed Implementation

[0035] To further understand the invention, the following detailed description of the invention will be provided in conjunction with specific embodiments.

[0036] Example 1: A preferred embodiment of the photopolymerization 3D printing aluminum-based ceramic core based on core-shell structure mineralizer modification according to the present invention, wherein the proportions of each substance in the aluminum-based ceramic core are: 70wt% aluminum-based ceramic powder, 10wt% core-shell structure mineralizer component, and 20wt% photosensitive resin component, wherein each substance in the core-shell structure mineralizer component is a core-shell structure powder. The aluminum-based ceramic powder is fused alumina powder, which includes three particle size ranges, with the following proportions: 48wt% for particles 10μm ≤ ≤ 30μm, 32wt% for particles 5μm ≤ < 10μm, and 20wt% for particles 1μm ≤ < 5μm.

[0037] The composition of the core-shell mineralizer is as follows: 7 wt% core-shell magnesium oxide powder, 23 wt% core-shell silicon dioxide powder, 12 wt% core-shell titanium oxide powder, 12 wt% core-shell zirconium silicate powder, 17 wt% core-shell mullite powder, 17 wt% core-shell sodium zirconium phosphate powder, 6 wt% core-shell cordierite powder, and 6 wt% core-shell diatomaceous earth powder.

[0038] The core-shell structured magnesium oxide powder, the core-shell structured silica powder, and the core-shell structured titanium oxide powder are respectively polystyrene-coated magnesium oxide powder, polystyrene-coated silica powder, and polystyrene-coated titanium oxide powder. The magnesium oxide powder, silica powder, and titanium oxide powder all include three particle size ranges, with each particle size range accounting for 46 wt% of 5 μm ≤ particle size ≤ 20 μm, 34 wt% of 1 μm ≤ particle size < 5 μm, and 20 wt% of 0.1 μm ≤ particle size < 1 μm.

[0039] The core-shell structured zirconium silicate powder and the core-shell structured mullite powder are respectively polystyrene-coated zirconium silicate powder and polystyrene-coated mullite powder. Both the zirconium silicate powder and the mullite powder include two particle size ranges, with each particle size range accounting for 60 wt% of 8 μm ≤ particle size ≤ 20 μm and 40 wt% of 1 μm ≤ particle size < 8 μm.

[0040] The core-shell structured sodium zirconium phosphate powder and the core-shell structured cordierite powder are respectively polystyrene-coated sodium zirconium phosphate powder and polystyrene-coated cordierite powder. Both the sodium zirconium phosphate powder and the cordierite powder include three particle size ranges, with each particle size range accounting for 35 wt% of 10 μm ≤ particle size ≤ 35 μm, 45 wt% of 5 μm ≤ particle size < 10 μm, and 20 wt% of 1 μm ≤ particle size < 5 μm.

[0041] The core-shell structured diatomaceous earth powder is polystyrene-coated diatomaceous earth. The diatomaceous earth includes two particle size categories, with each category having a particle size ratio of 60 wt% for particles ≤ 5 μm and ≤ 18 μm, and 40 wt% for particles ≤ 1 μm and < 5 μm.

[0042] The photosensitive resin component comprises, in the following proportions: photoinitiator 4 wt%, dispersant 8 wt%, and crosslinking aid 88 wt%. The photoinitiator is 1-hydroxycyclohexylphenyl ketone or trimethylbenzoyl-diphenylphosphine oxide; the dispersant is any one of BYK-111, BYK-9076, and KOS-110; and the crosslinking aid comprises, in the following proportions: 1,6-hexanediol diacrylate 48 wt%, trimethylolpropane triacrylate 28 wt%, isobornyl acrylate 12 wt%, and isobornyl methacrylate 12 wt%.

[0043] This embodiment also provides a method for preparing a photopolymerizable 3D printed aluminum-based ceramic core based on a core-shell structure mineralizer modification. The preparation method includes the following steps in sequence: Step 1: Prepare an aluminum-based ceramic core slurry according to the designed material ratio and process parameters; Step 2: Place the container containing the aluminum-based ceramic core slurry in a vacuum equipment for vacuum treatment to remove air bubbles inside the slurry; Step 3: Inject the aluminum-based ceramic core slurry into the material tank of the 3D printing equipment and print the aluminum-based ceramic core blank according to the designed core structure; Step 4: ... The aluminum-based ceramic core preform is placed in an ultrasonic cleaner for ultrasonic cleaning to remove uncured resin and surface residues. Then, it is transferred to an oven for drying to completely remove photopolymer residues and improve surface smoothness. Step five: The aluminum-based ceramic core preform is placed in a box-type muffle furnace for degreasing to remove organic matter from the preform. Step six: The aluminum-based ceramic core preform is placed in a sintering furnace for sintering to promote densification of the preform. After sintering, a photopolymerized 3D printed aluminum-based ceramic core based on a core-shell structure mineralizer modification is obtained.

[0044] In step one, the preparation of the aluminum-based ceramic core slurry includes the following steps in sequence: Step 1.1: Prepare core-shell structured magnesium oxide powder, core-shell structured silica powder, core-shell structured titanium oxide powder, core-shell structured zirconium silicate powder, core-shell structured mullite powder, core-shell structured sodium zirconium phosphate powder, core-shell structured cordierite powder, and core-shell structured diatomaceous earth powder according to the designed process parameters. Then, put the prepared core-shell structured powders into a V-type mixer and mix them evenly at room temperature at a mixing speed of 450 rpm. The mixing time is 0.8h, thus obtaining the core-shell structured mineralizer component; Step 1.2: Place the aluminum-based ceramic powder and the core-shell structured mineralizer component into a mixer, and stir at room temperature at a speed of 450rpm for 1.5h to ensure uniform mixing of all substances; Step 1.3: Place the photoinitiator, dispersant, and crosslinking aid into a mixer, and continue stirring at room temperature at a speed of 450rpm for 4.5h to ensure uniform mixing of all substances, thus obtaining the aluminum-based ceramic core slurry.

[0045] In step 1.1, the preparation methods for core-shell structured magnesium oxide powder, core-shell structured silica powder, core-shell structured titanium oxide powder, core-shell structured zirconium silicate powder, core-shell structured mullite powder, core-shell structured sodium zirconium phosphate powder, core-shell structured cordierite powder, and core-shell structured diatomaceous earth powder are the same. Among the various core-shell structured powders prepared, magnesium oxide powder, silica powder, titanium oxide powder, zirconium silicate powder, mullite powder, sodium zirconium phosphate powder, cordierite powder, and diatomaceous earth are the core materials of their respective core-shell structured powders. The specific preparation methods include the following steps in sequence: Step (1): Place the core material into a beaker containing deionized water, and then place the beaker into... The mixture of nuclear material was ultrasonically dispersed in an ultrasonic machine to obtain a nuclear material mixture. The mass ratio of nuclear material to deionized water was 1:35. The ultrasonic frequency was 20 kHz and the ultrasonic time was 12 min. Step (2): The nuclear material mixture in the beaker was transferred to a centrifuge tube, and then the centrifuge tube was placed in a benchtop high-speed centrifuge for centrifugation. The centrifugation speed was 7500 rpm and the centrifugation time was 12 min. After centrifugation, the mixture was allowed to stand to precipitate the nuclear material and the supernatant was removed. Step (3): Steps (1) to (2) were repeated twice to obtain the pretreated nuclear material. Step (4): The pretreated nuclear material was placed in a mixed solution of ethanol and deionized water. Stir evenly at room temperature to obtain premixed slurry A. The mass ratio of the core material to the mixed solution is 1:50, the mass ratio of ethanol to deionized water is 10:1, the stirring speed is 400 rpm, and the stirring time is 30 min; Step (5): Styrene monomer and benzoyl peroxide are mixed evenly at room temperature to obtain a mixed solution of the two. The mass ratio of styrene monomer to benzoyl peroxide is 16:1; The mixed solution of the two is slowly added to premixed slurry A and stirred evenly at room temperature to obtain premixed slurry B. The mass ratio of the mixed solution of the two to premixed slurry A is 5:1, the stirring speed is 400 rpm, and the stirring time is 25 min; Step (6): The container containing premixed slurry B is placed in a water bath and heated and stirred to coat the surface of the core material with organic matter, resulting in a core material mixed slurry. The heating temperature is 75℃, the stirring speed is 550rpm, and the stirring time is 4.5h. Step (7): The core material mixed slurry is placed in a drying oven for drying to remove ethanol and deionized water, resulting in a blocky core material solid. The drying temperature is 90℃ and the drying time is 9h. Step (8): The blocky core material solid is washed and filtered three times in ethanol, and then placed in a drying oven for drying to obtain polystyrene-coated core material. The drying temperature is 65℃ and the drying time is 9h.

[0046] In step two, the aluminum-based ceramic core slurry is subjected to vacuum treatment with a vacuum degree of -0.06 MPa and a holding time of 8 min.

[0047] In step three, the main process parameters involved in printing the aluminum-based ceramic core preform are: a cured layer thickness of 75 μm, an ultraviolet light wavelength of 380 nm, an exposure time of 7 s, and an exposure power of 20 mW / cm². 2 .

[0048] In step four, the cleaning agent used for ultrasonic cleaning is any one of ethanol, acetone, or isopropanol. The ultrasonic cleaning frequency is 90kHz, and the ultrasonic cleaning time is 4 minutes. The drying temperature is 105℃, and the drying time is 9 minutes.

[0049] In step five, the degreasing process of the aluminum-based ceramic core blank is as follows: First, the aluminum-based ceramic core blank is embedded in a sagger filled with kaolin, and then the sagger is placed in a box-type muffle furnace; under an air atmosphere, the temperature is increased from room temperature to 200℃ at a heating rate of 0.3℃ / min and held for 1.5h; the temperature is then increased to 320℃ at a heating rate of 0.3℃ / min and held for 1.5h; the temperature is then increased to 460℃ at a heating rate of 0.3℃ / min and held for 1.5h; the temperature is then increased to 600℃ at a heating rate of 0.3℃ / min and held for 1.5h, and then cooled to room temperature with the furnace.

[0050] In step six, the sintering process of the aluminum-based ceramic core blank is as follows: the sagger containing kaolin filler and the aluminum-based ceramic core blank is placed in the sintering furnace, and the temperature is raised from room temperature to 1100℃ at a heating rate of 4℃ / min under air atmosphere, and held for 1.2h; the temperature is then raised to 1315℃ at a heating rate of 2.5℃ / min, and held for 5h; then the temperature is lowered to 900℃ at a cooling rate of 2.5℃ / min, and cooled to room temperature with the furnace.

[0051] The microstructure of the core-shell structure powder (e.g., core-shell structure titanium dioxide powder) prepared in this embodiment is shown in Figure 1. The aluminum-based ceramic core slurry prepared using the core-shell structure mineralizer powder is shown in Figure 2. The prepared aluminum-based ceramic sample is shown in Figure 3. The prepared aluminum-based ceramic core is shown in Figure 4. The microstructure of the aluminum-based ceramic core is shown in Figures 5 and 6, where Figure 5 shows the pores and Figure 6 shows the sintering neck.

[0052] This embodiment has the following beneficial effects: (1) By constructing a core-shell structure mineralizer component, the shell forms a stable interface in the slurry system, effectively suppressing the agglomeration and phase separation caused by the physical differences between it and the matrix material, realizing the uniform dispersion of the mineralizer powder, and ensuring that the ceramic core maintains excellent shape integrity and dimensional stability. (2) The shell can adjust the contact timing and reaction rate between the mineralizer and the matrix particles, ensuring that the liquid phase is uniformly formed in the appropriate temperature range and continuously promotes densification, ultimately obtaining an aluminum-based ceramic core with uniform microstructure, excellent mechanical properties, and high batch consistency. (3) The core-shell structure mineralizer design breaks through the functional limitation of traditional mineralizers in simply reducing sintering temperature. The overall structure can guide the densification process, microstructure evolution, and final performance during sintering, thereby ensuring low-temperature sintering while synergistically improving the dimensional accuracy, structural integrity, and comprehensive performance of the core. (4) Effectively adjusting the sintering temperature of the 3D printed aluminum-based ceramic core blank reduces the generation of interlayer cracks during degreasing and sintering, resulting in an aluminum-based ceramic core with excellent comprehensive performance.

[0053] Example 2: Another preferred embodiment of the photopolymerization 3D printing aluminum-based ceramic core and its preparation method based on core-shell structure mineralizer modification according to the present invention, the material selection, preparation process, and beneficial effects are basically the same as in Example 1, except that: the proportions of each substance in the aluminum-based ceramic core are 67wt% aluminum-based ceramic powder, 15wt% core-shell structure mineralizer component, and 18wt% photosensitive resin component. The proportions of each particle size in the fused alumina powder are: 44wt% for particles 10μm ≤ ≤ 30μm, 38wt% for particles 5μm ≤ < 10μm, and 18wt% for particles 1μm ≤ < 5μm.

[0054] The composition of the core-shell mineralizer is as follows: 5 wt% core-shell magnesium oxide powder, 27 wt% core-shell silicon dioxide powder, 8 wt% core-shell titanium dioxide powder, 15 wt% core-shell zirconium silicate powder, 15 wt% core-shell mullite powder, 18 wt% core-shell sodium zirconium phosphate powder, 4 wt% core-shell cordierite powder, and 8 wt% core-shell diatomaceous earth powder.

[0055] The core-shell structured magnesium oxide powder, the core-shell structured silica powder, and the core-shell structured titanium oxide powder are respectively polystyrene-coated magnesium oxide powder, polystyrene-coated silica powder, and polystyrene-coated titanium oxide powder. The particle size distribution of each particle size in the magnesium oxide powder, silica powder, and titanium oxide powder is as follows: 42 wt% for particles with a particle size of 5 μm ≤ 20 μm, 40 wt% for particles with a particle size of 1 μm ≤ < 5 μm, and 18 wt% for particles with a particle size of 0.1 μm ≤ < 1 μm.

[0056] The core-shell structured zirconium silicate powder and the core-shell structured mullite powder are respectively polystyrene-coated zirconium silicate powder and polystyrene-coated mullite powder. The particle size distribution of the zirconium silicate powder and the mullite powder is as follows: 8μm≤particle size≤20μm accounts for 52wt%, and 1μm≤particle size<8μm accounts for 48wt%.

[0057] The core-shell structured sodium zirconium phosphate powder and the core-shell structured cordierite powder are respectively polystyrene-coated sodium zirconium phosphate powder and polystyrene-coated cordierite powder. The particle size distribution of the sodium zirconium phosphate powder and the cordierite powder is as follows: 10μm ≤ particle size ≤ 35μm accounts for 32wt%, 5μm ≤ particle size < 10μm accounts for 50wt%, and 1μm ≤ particle size < 5μm accounts for 18wt%.

[0058] The core-shell structured diatomaceous earth powder is polystyrene-coated diatomaceous earth, and the particle size distribution of the diatomaceous earth is as follows: 55 wt% for particles with a particle size of 5 μm ≤ 18 μm and 45 wt% for particles with a particle size of 1 μm ≤ < 5 μm.

[0059] The proportions of each substance in the photosensitive resin component are as follows: photoinitiator 1 wt%, dispersant 9 wt%, and crosslinking aid 90 wt%. The proportions of each substance in the crosslinking aid are as follows: 1,6-hexanediol diacrylate 42 wt%, trimethylolpropane triacrylate 34 wt%, isobornyl acrylate 10 wt%, and isobornyl methacrylate 14 wt%.

[0060] In step one, the preparation of the aluminum-based ceramic core slurry includes the following steps: preparing various core-shell structure powders according to the designed process parameters; mixing the various core-shell structure powders evenly in a V-type mixer at a mixing speed of 300 rpm for 1 hour to obtain the core-shell structure mineralizer component; mixing the aluminum-based ceramic powder and the core-shell structure mineralizer component evenly in a mixer at a mixing speed of 300 rpm for 2 hours; and mixing the photoinitiator, dispersant, and crosslinking aid evenly in a mixer at a mixing speed of 300 rpm for 6 hours to obtain the aluminum-based ceramic core slurry.

[0061] The preparation methods for various core-shell structure powders are the same. In the preparation process, magnesium oxide powder, silicon dioxide powder, titanium oxide powder, zirconium silicate powder, mullite powder, sodium zirconium phosphate powder, cordierite powder, and diatomaceous earth are the core materials of their respective core-shell structure powders. The specific preparation methods include the following steps in sequence: Step (1): Put the core material into a beaker containing deionized water, and then put the beaker into an ultrasonic machine for ultrasonic dispersion to obtain a mixture of core materials. The mass ratio of core material to deionized water is 1:30, and the ultrasonic frequency is 15kHz. Ultrasonic time 15 min; Step (2): Transfer the nuclear material mixture in the beaker to a centrifuge tube, and then place the centrifuge tube into a benchtop high-speed centrifuge for centrifugation at 7000 rpm for 15 min. Let it stand to allow the nuclear material to precipitate and remove the supernatant; Step (3): Repeat steps (1) to (2) twice to obtain the pretreated nuclear material; Step (4): Put the pretreated nuclear material into a mixed solution of ethanol and deionized water and stir evenly to obtain premixed slurry A. The mass ratio of nuclear material to mixed solution is as follows: The ratio of ethanol to deionized water is 1:45, the mass ratio of ethanol to deionized water is 8:1, the stirring speed is 300 rpm, and the stirring time is 40 min; Step (5): Styrene monomer and benzoyl peroxide are mixed evenly at room temperature to obtain a mixture of the two, the mass ratio of styrene monomer to benzoyl peroxide is 14:1; The mixture of the two is slowly added to premixed slurry A and stirred evenly to obtain premixed slurry B, the mass ratio of the mixture of the two to premixed slurry A is 4:1, the stirring speed is 300 rpm, and the stirring time is 30 min; Step (6): The container is filled with styrene monomer and benzoyl peroxide at room temperature. The container with premixed slurry B is placed in a water bath and heated and stirred to obtain a core material mixed slurry. The heating temperature is 70℃, the stirring speed is 500rpm, and the stirring time is 5h. Step (7): The core material mixed slurry is placed in a drying oven for drying treatment to obtain a blocky core material solid. The drying treatment temperature is 80℃ and the drying treatment time is 12h. Step (8): The blocky core material solid is placed in ethanol for washing and filtering three times, and then placed in a drying oven for drying treatment to obtain polystyrene-coated core material. The drying treatment temperature is 50℃ and the drying treatment time is 12h.

[0062] In step two, the aluminum-based ceramic core slurry is evacuated to a vacuum level of -0.06 MPa and held for 10 minutes.

[0063] In step three, the main process parameters involved in printing the aluminum-based ceramic core preform are: a cured layer thickness of 50 μm, an ultraviolet light wavelength of 300 nm, an exposure time of 10 s, and an exposure power of 10 mW / cm². 2 .

[0064] In step four, the ultrasonic cleaning frequency is 80kHz and the ultrasonic cleaning time is 5min; the drying temperature is 100℃ and the drying time is 10min.

[0065] In step five, the degreasing process of the aluminum-based ceramic core blank is as follows: under air atmosphere, the temperature is increased from room temperature to 200℃ at a heating rate of 0.1℃ / min and held for 1 hour; the temperature is then increased to 320℃ at a heating rate of 0.1℃ / min and held for 1 hour; the temperature is then increased to 460℃ at a heating rate of 0.1℃ / min and held for 1 hour; the temperature is then increased to 600℃ at a heating rate of 0.1℃ / min and held for 1 hour, and then cooled to room temperature with the furnace.

[0066] In step six, the sintering process of the aluminum-based ceramic core blank is as follows: under an air atmosphere, the temperature is increased from room temperature to 1100℃ at a heating rate of 3℃ / min and held for 1 hour; then the temperature is increased to 1280℃ at a heating rate of 2℃ / min and held for 6 hours; then the temperature is decreased to 900℃ at a cooling rate of 1℃ / min and cooled to room temperature in the furnace.

[0067] Example 3: Another preferred embodiment of the photopolymerization 3D printing aluminum-based ceramic core and its preparation method based on core-shell structure mineralizer modification according to the present invention, the material selection, preparation process, and beneficial effects are basically the same as in Example 1, except that: the proportions of each substance in the aluminum-based ceramic core are 75wt% aluminum-based ceramic powder, 5wt% core-shell structure mineralizer component, and 20wt% photosensitive resin component. The proportions of each particle size in the fused alumina powder are: 50wt% for particles 10μm ≤ ≤ 30μm, 25wt% for particles 5μm ≤ < 10μm, and 25wt% for particles 1μm ≤ < 5μm.

[0068] The composition of the core-shell mineralizer is as follows: 10 wt% core-shell magnesium oxide powder, 20 wt% core-shell silicon dioxide powder, 15 wt% core-shell titanium oxide powder, 8 wt% core-shell zirconium silicate powder, 18 wt% core-shell mullite powder, 17 wt% core-shell sodium zirconium phosphate powder, 8 wt% core-shell cordierite powder, and 4 wt% core-shell diatomaceous earth powder.

[0069] The core-shell structured magnesium oxide powder, the core-shell structured silica powder, and the core-shell structured titanium oxide powder are respectively polystyrene-coated magnesium oxide powder, polystyrene-coated silica powder, and polystyrene-coated titanium oxide powder. The particle size distribution of each particle size in the magnesium oxide powder, silica powder, and titanium oxide powder is as follows: 50 wt% for particles with a particle size of 5 μm ≤ 20 μm, 28 wt% for particles with a particle size of 1 μm ≤ < 5 μm, and 22 wt% for particles with a particle size of 0.1 μm ≤ < 1 μm.

[0070] The core-shell structured zirconium silicate powder and the core-shell structured mullite powder are respectively polystyrene-coated zirconium silicate powder and polystyrene-coated mullite powder. The particle size distribution of the zirconium silicate powder and the mullite powder is as follows: 68 wt% for particles with a particle size of 8 μm ≤ 20 μm and 32 wt% for particles with a particle size of 1 μm ≤ < 8 μm.

[0071] The core-shell structured sodium zirconium phosphate powder and the core-shell structured cordierite powder are respectively polystyrene-coated sodium zirconium phosphate powder and polystyrene-coated cordierite powder. The particle size distribution of the sodium zirconium phosphate powder and the cordierite powder is as follows: 10μm≤particle size≤35μm accounts for 38wt%, 5μm≤particle size<10μm accounts for 40wt%, and 1μm≤particle size<5μm accounts for 22wt%.

[0072] The core-shell structured diatomaceous earth powder is polystyrene-coated diatomaceous earth, and the particle size distribution of the diatomaceous earth is as follows: 65 wt% for particles with a particle size of 5 μm ≤ 18 μm and 35 wt% for particles with a particle size of 1 μm ≤ < 5 μm.

[0073] The proportions of each substance in the photosensitive resin component are as follows: photoinitiator 5 wt%, dispersant 10 wt%, and crosslinking aid 85 wt%. The proportions of each substance in the crosslinking aid are as follows: 1,6-hexanediol diacrylate 54 wt%, trimethylolpropane triacrylate 22 wt%, isobornyl acrylate 14 wt%, and isobornyl methacrylate 10 wt%.

[0074] In step one, the preparation of the aluminum-based ceramic core slurry includes the following steps: preparing various core-shell structure powders according to the designed process parameters; mixing the various core-shell structure powders evenly in a V-type mixer at a mixing speed of 600 rpm for 0.5 h to obtain the core-shell structure mineralizer component; mixing the aluminum-based ceramic powder and the core-shell structure mineralizer component evenly in a mixer at a mixing speed of 600 rpm for 1 h; and mixing the photoinitiator, dispersant, and crosslinking aid evenly in a mixer at a mixing speed of 600 rpm for 3 h to obtain the aluminum-based ceramic core slurry.

[0075] The preparation methods for various core-shell structure powders are the same. In the preparation process, magnesium oxide powder, silicon dioxide powder, titanium oxide powder, zirconium silicate powder, mullite powder, sodium zirconium phosphate powder, cordierite powder, and diatomaceous earth are the core materials of their respective core-shell structure powders. The specific preparation methods include the following steps in sequence: Step (1): Put the core material into a beaker containing deionized water, and then put the beaker into an ultrasonic machine for ultrasonic dispersion to obtain a core material mixture. The mass ratio of the core material to deionized water is 1:40, and the ultrasonic frequency is 25kHz. Ultrasonic time 10 min; Step (2): Transfer the nuclear material mixture in the beaker to a centrifuge tube, and then place the centrifuge tube into a benchtop high-speed centrifuge for centrifugation at 8000 rpm for 10 min. Let it stand to allow the nuclear material to precipitate and remove the supernatant; Step (3): Repeat steps (1) to (2) twice to obtain the pretreated nuclear material; Step (4): Put the pretreated nuclear material into a mixed solution of ethanol and deionized water and stir evenly to obtain premixed slurry A. The mass ratio of nuclear material to mixed solution is as follows: The ratio of ethanol to deionized water is 12:1, the stirring speed is 500 rpm, and the stirring time is 20 min; Step (5): Styrene monomer and benzoyl peroxide are mixed evenly at room temperature to obtain a mixture of the two, with a mass ratio of styrene monomer to benzoyl peroxide of 18:1; The mixture of the two is slowly added to premixed slurry A and stirred evenly to obtain premixed slurry B, with a mass ratio of the mixture of the two to premixed slurry A of 6:1, the stirring speed is 500 rpm, and the stirring time is 20 min; Step (6): The mixture of styrene monomer and benzoyl peroxide is ..., the stirring speed is 500 rpm, and the stirring time is 20 min; The container containing premixed slurry B is placed in a water bath and heated and stirred to obtain a core material mixed slurry. The heating temperature is 80℃, the stirring speed is 600rpm, and the stirring time is 4h. Step (7): The core material mixed slurry is placed in a drying oven for drying treatment to obtain a blocky core material solid. The drying treatment temperature is 100℃ and the drying treatment time is 6h. Step (8): The blocky core material solid is placed in ethanol for washing and filtering three times, and then placed in a drying oven for drying treatment to obtain polystyrene-coated core material. The drying treatment temperature is 80℃ and the drying treatment time is 6h.

[0076] In step two, the aluminum-based ceramic core slurry is evacuated to a vacuum level of -0.07 MPa and held for 5 minutes.

[0077] In step three, the main process parameters involved in printing the aluminum-based ceramic core preform are: a cured layer thickness of 100 μm, an ultraviolet light wavelength of 450 nm, an exposure time of 3 s, and an exposure power of 30 mW / cm². 2 .

[0078] In step four, the ultrasonic cleaning frequency is 100kHz and the ultrasonic cleaning time is 3min; the drying temperature is 110℃ and the drying time is 8min.

[0079] In step five, the degreasing process of the aluminum-based ceramic core blank is as follows: under air atmosphere, the temperature is increased from room temperature to 200℃ at a heating rate of 0.5℃ / min and held for 2 hours; the temperature is then increased to 320℃ at a heating rate of 0.5℃ / min and held for 2 hours; the temperature is then increased to 460℃ at a heating rate of 0.5℃ / min and held for 2 hours; the temperature is then increased to 600℃ at a heating rate of 0.5℃ / min and held for 2 hours, and then cooled to room temperature with the furnace.

[0080] In step six, the sintering process of the aluminum-based ceramic core blank is as follows: under an air atmosphere, the temperature is increased from room temperature to 1100℃ at a heating rate of 5℃ / min and held for 1.5h; then the temperature is increased to 1350℃ at a heating rate of 3℃ / min and held for 4h; then the temperature is decreased to 900℃ at a cooling rate of 4℃ / min and cooled to room temperature in the furnace.

[0081] Comparative Example: The aluminum-based ceramic core of this comparative example contains 70 wt% aluminum-based ceramic powder, 10 wt% mineralizer, and 20 wt% photosensitive resin. The aluminum-based ceramic powder and photosensitive resin components are essentially the same as in Example 1. The mineralizer component contains 20 wt% magnesium oxide powder, 38 wt% silica powder, 20 wt% zirconium silicate powder, and 22 wt% mullite powder. The particle size of each component in the mineralizer component is essentially the same as in Example 1. The preparation process and process parameters of the aluminum-based ceramic core are essentially the same as in Example 1. Compared with the above three examples, the mineralizer component of this comparative example lacks titanium oxide powder, sodium zirconium phosphate powder, cordierite powder, and diatomaceous earth. Furthermore, the mineralizer component of this comparative example is not prepared as a core-shell structure powder.

[0082] The aluminum-based ceramic cores (after sintering) prepared in the above embodiments and comparative examples were subjected to performance tests. The test conditions, test equipment, and test environment were all the same. The test results are shown in Table 1.

[0083] The test results in Table 1 show that the three embodiments introduced a core-shell structure mineralizer component, which, through material and structural design, simultaneously possesses multiple roles: the outer shell can regulate the rheological properties of the slurry and improve printing efficiency; the core, as a high-temperature stable phase, can both inhibit abnormal grain growth during sintering and act as a reinforcing phase to improve the strength and toughness of the core; the overall structure can guide the densification process, microstructure evolution, and final performance during sintering, thereby synergistically improving the dimensional accuracy, structural integrity, and overall performance of the core while ensuring low-temperature sintering.

[0084] The raw materials used in the above embodiments and comparative examples were purchased from Aladdin Reagent Co., Ltd. and Sinopharm Chemical Reagent Co., Ltd.

[0085] Special Note: The technical solution of this invention involves numerous parameters, and the synergistic effects between these parameters must be comprehensively considered to achieve the beneficial effects and significant progress of this invention. Furthermore, the value ranges of each parameter in the technical solution were obtained through extensive experimentation. For each parameter and the combinations thereof, the inventors have recorded a large amount of experimental data; however, due to space limitations, the specific experimental data is not disclosed here.

[0086] It will be readily understood by those skilled in the art that this invention includes any combination of the inventive description and specific embodiments outlined in the foregoing specification, as well as the various parts shown in the accompanying drawings. Due to space limitations and for the sake of brevity, not all of these combinations have been described in detail. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A photopolymerizable 3D printed aluminum-based ceramic core based on a core-shell structure mineralizer modification, characterized in that, The mass percentage of each substance in the aluminum-based ceramic core is as follows: 65-75 wt% aluminum-based ceramic powder, 5-15 wt% core-shell structure mineralizer component, and 15-25 wt% photosensitive resin component, with the sum of the contents of each substance being 100 wt%; each substance in the core-shell structure mineralizer component is a core-shell structure powder.

2. The photopolymerization 3D printing aluminum-based ceramic core based on core-shell structure mineralizer modification according to claim 1, characterized in that, The aluminum-based ceramic powder is fused alumina powder, which includes three particle size ranges. The mass percentage of each particle size range in the fused alumina powder is as follows: 10μm≤particle size≤30μm accounts for 42-55wt%, 5μm≤particle size<10μm accounts for 25-38wt%, and 1μm≤particle size<5μm accounts for 15-25wt%.

3. The photopolymerization 3D printing aluminum-based ceramic core based on core-shell structure mineralizer modification according to claim 2, characterized in that, The mass percentage of each substance in the core-shell structured mineralizer component is as follows: 5-10 wt% core-shell structured magnesium oxide powder, 18-28 wt% core-shell structured silica powder, 8-15 wt% core-shell structured titanium oxide powder, 8-15 wt% core-shell structured zirconium silicate powder, 15-18 wt% core-shell structured mullite powder, 15-18 wt% core-shell structured sodium zirconium phosphate powder, 4-8 wt% core-shell structured cordierite powder, and 4-8 wt% core-shell structured diatomaceous earth powder, with the sum of the contents of each substance being 100 wt%.

4. The photopolymerization 3D printing aluminum-based ceramic core based on core-shell structure mineralizer modification according to claim 3, characterized in that, The core-shell structured magnesium oxide powder, the core-shell structured silica powder, and the core-shell structured titanium oxide powder are respectively polystyrene-coated magnesium oxide powder, polystyrene-coated silica powder, and polystyrene-coated titanium oxide powder. Each of the magnesium oxide powder, silica powder, and titanium oxide powder comprises three particle size ranges, with each particle size range accounting for 42-52 wt% of the mass percentage of the magnesium oxide powder, silica powder, and titanium oxide powder respectively: 5μm ≤ particle size ≤ 20μm, 28-40 wt% of the mass percentage ... The particle size distribution is as follows: 8μm ≤ particle size ≤ 20μm accounts for 52-68wt%, and 1μm ≤ particle size < 8μm accounts for 32-48wt%. The core-shell structured sodium zirconium phosphate powder and the core-shell structured cordierite powder are respectively polystyrene-coated sodium zirconium phosphate powder and polystyrene-coated cordierite powder. Both the sodium zirconium phosphate powder and the cordierite powder include three particle size ranges, with each range accounting for 10% of the total mass of the sodium zirconium phosphate powder and the cordierite powder, respectively. Particles with a diameter of μm ≤ 35μm account for 28-42 wt%, particles with a diameter of 5μm ≤ < 10μm account for 40-50 wt%, and particles with a diameter of 1μm ≤ < 5μm account for 15-25 wt%. The core-shell structured diatomaceous earth powder is polystyrene-coated diatomaceous earth, which includes two particle size ranges. The mass percentage of each particle size range in the diatomaceous earth is as follows: particles with a diameter of 5μm ≤ 18μm account for 55-65 wt%, and particles with a diameter of 1μm ≤ < 5μm account for 35-45 wt%.

5. The photopolymerization 3D printing aluminum-based ceramic core based on core-shell structure mineralizer modification according to claim 4, characterized in that, The mass percentage of each substance in the photosensitive resin component is as follows: photoinitiator 1-5 wt%, dispersant 5-10 wt%, crosslinking aid 85-90 wt%, and the sum of the contents of each substance is 100 wt%.

6. The photopolymerization 3D printing aluminum-based ceramic core based on core-shell structure mineralizer modification according to claim 5, characterized in that, The photoinitiator is 1-hydroxycyclohexylphenyl ketone and / or trimethylbenzoyl-diphenylphosphine oxide; the dispersant is any one or more of BYK-111, BYK-9076, and KOS-110; the mass percentage of each substance in the crosslinking aid is 42-55 wt% of 1,6-hexanediol diacrylate, 22-35 wt% of trimethylolpropane triacrylate, 10-14 wt% of isobornyl acrylate, and 10-14 wt% of isobornyl methacrylate.

7. A method for preparing a photopolymerizable 3D printed aluminum-based ceramic core based on a core-shell structure mineralizer modified according to any one of claims 1-6, characterized in that, The preparation method includes the following steps in sequence: Step 1: Prepare aluminum-based ceramic core slurry according to the designed material ratio and process parameters; Step 2: Place the container containing the aluminum-based ceramic core slurry in a vacuum equipment for vacuum treatment to remove air bubbles inside the slurry; Step 3: Inject the aluminum-based ceramic core slurry into the material tank of the 3D printing equipment and print the aluminum-based ceramic core blank according to the designed core structure; Step 4: Place the aluminum-based ceramic core blank in an ultrasonic cleaner for ultrasonic cleaning to remove uncured resin and surface residues, and then transfer it to an oven for drying to completely remove photopolymer residues and improve surface smoothness; Step 5: Place the aluminum-based ceramic core blank in a box-type muffle furnace for degreasing treatment to remove organic matter from the blank; Step 6: Place the aluminum-based ceramic core blank in a sintering furnace for sintering treatment to promote densification of the blank. After sintering, a photocurable 3D printed aluminum-based ceramic core modified with a core-shell structure mineralizer is obtained.

8. The method for preparing a photopolymer 3D printed aluminum-based ceramic core based on core-shell structure mineralizer modification according to claim 7, characterized in that, In step one, the preparation of the aluminum-based ceramic core slurry includes the following steps in sequence: Step 1.1: Prepare core-shell structured magnesium oxide powder, core-shell structured silica powder, core-shell structured titanium oxide powder, core-shell structured zirconium silicate powder, core-shell structured mullite powder, core-shell structured sodium zirconium phosphate powder, core-shell structured cordierite powder, and core-shell structured diatomaceous earth powder according to the designed process parameters. Then, put the prepared core-shell structured powders into a V-type mixer and mix them evenly at room temperature. The mixing speed is 300-600 rpm, and the mixing time is [not specified]. Step 1.2: Place the aluminum-based ceramic powder and the core-shell structured mineralizer component into a mixer and stir at room temperature at a speed of 300-600 rpm for 1-2 hours to ensure uniform mixing of all substances. Step 1.3: Place the photoinitiator, dispersant, and crosslinking aid into a mixer and continue stirring at room temperature at a speed of 300-600 rpm for 3-6 hours to ensure uniform mixing of all substances, thus obtaining the aluminum-based ceramic core slurry.

9. The method for preparing a photopolymer 3D printed aluminum-based ceramic core based on core-shell structure mineralizer modification according to claim 8, characterized in that, In step 1.1, the preparation methods for core-shell structured magnesium oxide powder, core-shell structured silica powder, core-shell structured titanium oxide powder, core-shell structured zirconium silicate powder, core-shell structured mullite powder, core-shell structured sodium zirconium phosphate powder, core-shell structured cordierite powder, and core-shell structured diatomaceous earth powder are the same. Among the various core-shell structured powders prepared, magnesium oxide powder, silica powder, titanium oxide powder, zirconium silicate powder, mullite powder, sodium zirconium phosphate powder, cordierite powder, and diatomaceous earth are the core materials of their respective core-shell structured powders. The specific preparation methods include the following steps in sequence: Step (1): Put the core material into a beaker containing deionized water, and then put the beaker into an ultrasonic machine for ultrasonic dispersion to obtain the core material. The mass ratio of nuclear material to deionized water in the mixture is 1:30-40, the ultrasonic frequency is 15-25kHz, and the ultrasonic time is 10-15min; Step (2): Transfer the nuclear material mixture in the beaker to a centrifuge tube, and then put the centrifuge tube into a benchtop high-speed centrifuge for centrifugation at a speed of 7000-8000rpm for 10-15min. After centrifugation, let it stand to allow the nuclear material to precipitate and remove the supernatant; Step (3): Repeat steps (1) to (2) twice to obtain the pretreated nuclear material; Step (4): Put the pretreated nuclear material into a mixed solution of ethanol and deionized water and stir evenly at room temperature to obtain a premixed slurry. A, the mass ratio of nuclear material to mixed solution is 1:45-55, the mass ratio of ethanol to deionized water is 8-12:1, the stirring speed is 300-500 rpm, and the stirring time is 20-40 min; Step (5): Styrene monomer and benzoyl peroxide are mixed evenly at room temperature to obtain a mixed solution of the two, the mass ratio of styrene monomer to benzoyl peroxide is 14-18:1; the mixed solution of the two is slowly added to premixed slurry A, and stirred evenly at room temperature to obtain premixed slurry B, the mass ratio of the mixed solution of the two to premixed slurry A is 4-6:1, the stirring speed is 300-500 rpm, and the stirring time is 20-30 min; Step (6): the premixed slurry B is added to the premixed slurry A. The container of slurry B is placed in a water bath for heating and stirring, so that the organic matter is coated on the surface of the core material to obtain a mixed core material slurry. The heating temperature is 70-80℃, the stirring speed is 500-600rpm, and the stirring time is 4-5h. Step (7): The mixed core material slurry is placed in a drying oven for drying treatment to remove ethanol and deionized water, and blocky core material solid is obtained. The drying treatment temperature is 80-100℃, and the drying treatment time is 6-12h. Step (8): The blocky core material solid is placed in ethanol for washing and filtration three times, and then placed in a drying oven for drying treatment to obtain polystyrene-coated core material. The drying treatment temperature is 50-80℃, and the drying treatment time is 6-12h.

10. The method for preparing a photopolymer 3D printed aluminum-based ceramic core based on core-shell structure mineralizer modification according to claim 9, characterized in that, In step two, the aluminum-based ceramic core slurry is subjected to vacuum treatment at a vacuum level of -0.06 to -0.07 MPa for a holding time of 5-10 minutes. In step three, the main process parameters involved in printing the aluminum-based ceramic core preform are: a cured layer thickness of 50-100 μm, an ultraviolet wavelength of 300-450 nm, an exposure time of 3-10 s, and an exposure power of 10-30 mW / cm². 2 In step four, the ultrasonic cleaning agent used is any one of ethanol, acetone, or isopropanol. The ultrasonic cleaning frequency is 80-100kHz, and the ultrasonic cleaning time is 3-5 minutes. The drying temperature is 100-110℃, and the drying time is 8-10 minutes. In step five, the degreasing process of the aluminum-based ceramic core blank is as follows: First, the aluminum-based ceramic core blank is embedded in a crucible filled with kaolin, and then the crucible is placed in a box-type muffle furnace. Under air atmosphere, the temperature is increased from room temperature to 200℃ at a heating rate of 0.1-0.5℃ / min and held for 1-2 hours. The temperature is then increased to 320℃ at a heating rate of 0.1-0.5℃ / min and held for 1-2 hours. The temperature is increased to 460℃ at a heating rate of 0.1-0.5℃ / min and held for 1-2 hours; then increased to 600℃ at a heating rate of 0.1-0.5℃ / min and held for 1-2 hours, followed by cooling to room temperature in the furnace. In step six, the sintering process of the aluminum-based ceramic core blank is as follows: the sagger containing kaolin filler and the aluminum-based ceramic core blank is placed in the sintering furnace, and under an air atmosphere, the temperature is increased from room temperature to 1100℃ at a heating rate of 3-5℃ / min and held for 1-1.5 hours; then increased to 1280-1350℃ at a heating rate of 2-3℃ / min and held for 4-6 hours; then decreased to 900℃ at a cooling rate of 1-4℃ / min and cooled to room temperature in the furnace.

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