A method for preparing a photocured 3D printed multi-material ceramic structure

Abstract

The present application relates to the technical field of ceramic 3D printing, and particularly relates to a preparation method of a light-cured 3D printing multi-material ceramic structural part, which comprises the following steps: ceramic powder A, mixed ceramic powder and ceramic powder B are respectively prepared into light-cured ceramic slurries with gradient contents by being sequentially mixed with light-cured monomers, dispersants, photoinitiators and low-molecular-weight plasticizers; the light-cured ceramic slurries are integratedly light-cured and printed in sequence according to the solid content gradient by using a multi-material light-cured 3D printing forming machine to prepare a multi-material ceramic structural part green body with a solid content gradient; the multi-material ceramic structural part green body is prepared; the multi-material ceramic structural part green body is debound under argon to obtain a multi-material ceramic structural part after sintering. The present application solves the problem that, in the process of traditional debinding of light-cured 3D printing forming multi-material ceramic structural parts, different ceramic material green bodies are prone to defects due to large component differences.

Description

Technical Field

[0001] This invention relates to the field of ceramic 3D printing technology, specifically to a method for preparing multi-material ceramic structural parts by photopolymerization 3D printing. Background Technology

[0002] With the development of modern industrial technology and the economy, the demand for processing complex-shaped ceramic structural components is increasing, especially the demand for high-precision integrated forming of multi-material ceramic structural components. This can meet the application needs of multi-material ceramic structural components in aerospace, automotive processing, micro-nano devices, semiconductors, and other fields. Additive manufacturing technology can meet the processing needs of complex-shaped ceramic structural components, among which stereolithography additive manufacturing technology can meet the processing needs of high-precision complex-shaped ceramic structural components. Specifically, digital light processing (DLP) forming processes based on multi-slurry baths and forming processes based on partitioned coating-stereolithography can meet the processing needs of complex-shaped ceramic structural components made of multiple ceramic materials.

[0003] However, photopolymerization 3D printing is based on the layer-by-layer selective photopolymerization of ceramic slurries. Because the organic content of the ceramic green bodies in photopolymerization 3D printing is excessively high, typically reaching 40-50% vol%, the removal of organic matter during the debinding process easily leads to defects. This is especially true in the photopolymerization forming of multi-material ceramics. Since different types of ceramic green bodies are photopolymerized from ceramic slurries with different compositions, and these slurries exhibit significant differences in organic formation and photopolymerization behavior, the chemical composition and physical state of the organic matter in the photopolymerized ceramic green bodies vary considerably. This makes interface formation and defects highly likely during the debinding process. Therefore, debinding failures in multi-material ceramic structures are a serious obstacle to the development of multi-material photopolymerization 3D printing technology.

[0004] For example, the Chinese invention patent "Apparatus and Method for Photopolymerization of Multi-Material Forming in Ceramic Additive Manufacturing" (CN202310408377.X) reports an apparatus and method for photopolymerization of multi-material forming in ceramic additive manufacturing. This method overcomes the shortcomings of material contamination during photopolymerization of multi-material ceramic printing, or the limitation of only being able to achieve multi-material photopolymerization printing in the longitudinal direction. However, it does not discuss the debinding process for photopolymerization 3D printed multi-material ceramic structural parts. Similarly, the literature "High-resolution multiceramic additive manufacturing based on digital lightprocessing" (Additive Manufacturing, 2022, 54, 102732.) reports the use of multi-slurry tank multi-material photopolymerization 3D printing technology to form structural parts of different ceramic materials in the Z-axis direction, but it also does not discuss the debinding process and debinding performance of multi-ceramic green bodies in detail. Summary of the Invention

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a method for preparing multi-material ceramic structural parts by photopolymerization 3D printing. Through slurry composition optimization, debinding process optimization, and gradient design, the multi-material ceramic structural parts formed by the multi-material photopolymerization 3D printer exhibit good interface bonding and no obvious defects after debinding. This solves the technical problem of easy defect generation caused by the large differences in the green body composition of different ceramic materials during the traditional debinding process.

[0006] To achieve the above objectives, according to a first aspect of the present invention, a method for preparing photopolymer 3D printed multi-material ceramic structural parts is provided, comprising the following steps:

[0007] (1) Ceramic powder A, mixed ceramic powder, and ceramic powder B are respectively formulated with photocurable monomer, dispersant, photoinitiator, and low molecular weight plasticizer to prepare photocurable ceramic slurry, wherein the solid content of ceramic powder A, mixed ceramic powder, and ceramic powder B in the corresponding photocurable ceramic slurry changes in a uniform gradient manner; wherein, the mixed ceramic powder is a mixture of ceramic powder A and ceramic powder B; wherein, the low molecular weight plasticizer is an aliphatic plasticizer or phthalic plasticizer with a molecular weight of less than 400 and a decomposition temperature of less than 300℃;

[0008] (2) The photocurable ceramic slurry is used in a multi-material photocurable 3D printing machine to perform integrated photocurable printing according to the solid content gradient of the photocurable ceramic slurry to prepare a green body of a multi-material ceramic structure with a solid content gradient.

[0009] (3) The green body of the multi-material ceramic structure is degreased and sintered under argon to produce a multi-material ceramic structure.

[0010] As a preferred embodiment of the present invention, the low molecular weight plasticizer is polyethylene glycol, polypropylene glycol, diethylene glycol, or dibutyl phthalate; wherein the molecular weight of the polyethylene glycol and the polypropylene glycol is 200.

[0011] In the photocurable ceramic slurry, the volume ratio of the low molecular weight plasticizer to the photocurable monomer is from 1.5:8.5 to 2.5:7.5.

[0012] As a preferred embodiment of the present invention, the solid content of the ceramic powder A, the mixed ceramic powder, and the ceramic powder B in the corresponding photocurable ceramic slurry is 40-60 vol%.

[0013] At least one light-cured ceramic slurry with a mixed solid content of ceramic powders is prepared according to the difference in solid content between ceramic powder A and ceramic powder B in the corresponding light-cured ceramic slurry, and the solid content difference between the two light-cured ceramic slurries with adjacent solid contents is 1-2.5 vol.

[0014] As a preferred embodiment of the present invention, both ceramic powder A and ceramic powder B are selected from one of silicon oxide, zirconium oxide, aluminum oxide, hydroxyapatite, calcium phosphate, silicon carbide, silicon nitride, aluminum nitride, or titanium nitride, and the ceramic powder A and ceramic powder B are made of different materials.

[0015] As a preferred embodiment of the present invention, the photocurable monomer is a mixture of monofunctional photocurable monomers, difunctional photocurable monomers and polyfunctional photocurable monomers; the amount of the photocurable monomer added accounts for 30-50 vol% of the photocurable ceramic slurry;

[0016] The volume ratio of the monofunctional photocurable monomer to the polyfunctional photocurable monomer is 1:4 to 4:1, and the total volume ratio of the monofunctional photocurable monomer to the polyfunctional photocurable monomer is 50 vol% of the photocurable monomer.

[0017] The monofunctional monomer is one of lauryl acrylate, ethoxyethoxyethyl acrylate, isobornyl acrylate, and acryloylmorpholine; the difunctional photocurable monomer is one of 1,6-hexanediol acrylate, tripropylene glycol diacrylate, dipropylene glycol acrylate, propionyl dipentylene glycol acrylate, and 1,9-nonanediol diacrylate; the polyfunctional photocurable monomer is one of trimethylolpropane triacrylate, ethoxytrimethylolpropane triacrylate, and pentaerythritol triacrylate.

[0018] As a preferred embodiment of the present invention, the dispersant is one of the polymer copolymer dispersants BYK111, BYK183, BYK163, BYK180, Sago9090, and Sago9073, and the amount of the dispersant added accounts for 2-5 wt% of the photocurable ceramic slurry.

[0019] The photoinitiator is one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 1-hydroxycyclohexylphenyl ketone, and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and the amount of the photoinitiator added accounts for 2-4 wt% of the photocurable ceramic slurry.

[0020] As a preferred embodiment of the present invention, the degreasing temperature is raised from room temperature to 600°C at a rate of 0.1–0.6°C / min, and the temperature is maintained at 300°C, 340°C, 400°C, 420°C, and 500°C for 1–3 hours respectively.

[0021] As a preferred embodiment of the present invention, the photocurable ceramic slurry further comprises aliphatic polyurethane acrylate or epoxy acrylate, and the volume ratio of the aliphatic polyurethane acrylate or the epoxy acrylate to the photocurable monomer is 1:9 to 3:7.

[0022] As a preferred embodiment of the present invention, the photocurable ceramic slurry further comprises a sintering aid;

[0023] The sintering aid is one or more of yttrium oxide powder, aluminum oxide powder, and magnesium oxide powder;

[0024] The amount of the sintering aid added accounts for 2-4 wt% of the photocurable ceramic slurry.

[0025] According to another aspect of the present invention, a multi-material ceramic structural component prepared by the preparation method described in the first aspect is provided.

[0026] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages:

[0027] (1) The present invention, through the slurry composition, specifically due to the introduction of low molecular weight plasticizers (aliphatic plasticizers or phthalic plasticizers with molecular weight below 400 and decomposition temperature below 300℃), ensures that after the prepared multi-material ceramic green body is thermally degreased, there are no obvious defects generated at the interface between different materials, and the interface bonding is good, which greatly improves the performance of photopolymerization forming 3D printing to prepare multi-material ceramic structural parts.

[0028] (2) Through the optimization of slurry composition and gradient structure, combined with the introduction of low molecular weight plasticizer and the design of gradient structure, the prepared multi-material ceramic green body has no obvious defects generated at the interface between different materials after thermal debinding, and the interface bonding is good, which greatly improves the performance of photopolymerization forming 3D printing to prepare multi-material ceramic structural parts.

[0029] (3) Through comprehensive optimization of slurry composition, degreasing process and gradient structure, the present invention enables the multi-material ceramic green body to have good interfacial bonding between different materials after thermal degreasing. The degreasing time required for multi-material ceramic green body is reduced during the preparation process, which can effectively improve the processing efficiency of multi-material photopolymerization 3D printing to prepare multi-material ceramic structural parts. Attached Figure Description

[0030] Figure 1 These are TG / DSC data graphs of ceramic green bodies under different slurry compositions and debinding processes in Comparative Examples 1-3 of this invention; wherein, Figure 1 In Figure a, the TG / DSC analysis of the multi-material ceramic structural component prepared in Comparative Example 1 is shown. Figure 1 Figure b shows the TG / DSC analysis of the multi-material ceramic structural component prepared in Comparative Example 2. Figure 1 In Figure c, the TG / DSC analysis of the multi-material ceramic structural component prepared in Comparative Example 3 is shown.

[0031] Figure 2 TG / DSC data for ceramic green bodies with different gradient designs as exemplified in Embodiment 1 of the present invention;

[0032] Figure 3 These are SEM images of multi-ceramic material splines and complex-shaped ceramic material structural parts after degreasing, taken under different slurry compositions, degreasing processes, and gradient designs in Comparative Examples 1-3 and Example 1 of this invention; wherein, Figure 3 In the image, 'a' is the SEM image of the sample corresponding to Comparative Example 1. Figure 3 In Figure b, the SEM image of the sample corresponding to Comparative Example 2 is shown. Figure 3 In the image, c is the SEM image of the sample corresponding to Comparative Example 3; Figure 3 In the image, d represents the SEM image of the sample corresponding to Example 1. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0034] This invention provides a method for preparing photopolymer 3D printed multi-material ceramic structural parts, comprising the following steps:

[0035] (1) Preparation of photocurable ceramic slurry:

[0036] Ceramic powder A, mixed ceramic powder, and ceramic powder B are dried, ground, and sieved; wherein the mixed ceramic powder is a mixture of ceramic powder A and ceramic powder B, and the mass ratio of ceramic powder A to ceramic powder B is 2:8-25:5.

[0037] The sieved ceramic powder A, mixed ceramic powder, and ceramic powder B were sequentially and separately formulated with photocurable monomers, dispersants, photoinitiators, and low molecular weight plasticizers to prepare photocurable ceramic slurries with gradient solid content. That is, the solid content of ceramic powder A, mixed ceramic powder, and ceramic powder B in the corresponding photocurable ceramic slurries showed a uniform gradient. The low molecular weight plasticizer was an aliphatic plasticizer or a phthalic plasticizer with a molecular weight of less than 400 and a decomposition temperature of less than 300℃.

[0038] (2) Preparation of green blanks for multi-material ceramic structural components:

[0039] Using the aforementioned photocurable ceramic slurry as raw material, a multi-material photocurable 3D printing machine is used to import the processing model and perform photocurable printing according to the order of gradient solid content (solid content from high to low or solid content from low to high) to form a green body of a multi-material ceramic structure with a solid content gradient.

[0040] (3) Degreasing and sintering:

[0041] The above-mentioned exothermic degreasing furnace for green billets is designed to remove the atmosphere, rate, and holding time.

[0042] Finally, multi-material ceramic structural components with controllable microstructures were obtained through high-temperature sintering.

[0043] Furthermore, the aforementioned low molecular weight plasticizer is polyethylene glycol 200 (PEG200; molecular weight 200; decomposition temperature 200℃), polypropylene glycol 200 (PPG200; molecular weight 200; decomposition temperature 158℃), diethylene glycol (DEG: molecular weight 106.12; decomposition temperature 167℃) or dibutyl phthalate (DBP; molecular weight 278.34; decomposition temperature 190℃); and the volume ratio of the low molecular weight plasticizer to the photocurable monomer in the same photocurable ceramic slurry is from 1.5:8.5 to 2.5:7.5.

[0044] Furthermore, the solid content of different ceramic powders in the photocurable ceramic slurry ranges from 40-60 vol%. Both ceramic powder A and ceramic powder B are selected from one of silicon oxide, zirconium oxide, alumina, hydroxyapatite, calcium phosphate, silicon carbide, silicon nitride, aluminum nitride, or titanium nitride, and the raw materials selected for ceramic powder A and ceramic powder B are different.

[0045] At least one photocurable ceramic slurry with mixed solid content of ceramic powder A and ceramic powder B is prepared according to the difference in solid content between the two photocurable ceramic slurries, and the solid content difference between two photocurable ceramic slurries with adjacent solid contents is 1-2.5 vol%. For example, the interface between a ceramic green body with a high solid content of 50-60 vol% and a ceramic green body with a low solid content of 40-45 vol% can be designed with a multi-layer graded transition layer with a solid content of 45-50 vol%.

[0046] Furthermore, the photocurable monomer is a mixture of monofunctional, difunctional, and multifunctional photocurable monomers; the amount of photocurable monomer added accounts for 30-50 vol% of the photocurable ceramic slurry.

[0047] The volume ratio of monofunctional photocurable monomers, difunctional photocurable monomers, and polyfunctional photocurable monomers is 1:5:4 to 4:5:1, and the total volume ratio of monofunctional and polyfunctional photocurable monomers is 50 vol% of the photocurable monomers. In the description of this invention, the polyfunctional photocurable monomer is a photocurable monomer with a light energy greater than or equal to 3, as known in the art.

[0048] The monofunctional monomer is one of lauryl acrylate (LA), ethoxyethoxyethyl acrylate (EOEOEA), isobornyl acrylate (IBOA), and acrylmorpholine (ACMO).

[0049] The bifunctional photocurable monomer is one of 1,6-hexanediol acrylate (HDDA), tripropylene glycol diacrylate (TPGDA), dipropylene glycol acrylate (DPGDA), dinepentylene glycol acrylate (NPG2PODA), and 1,9-nonanediol diacrylate (NDDA).

[0050] The multifunctional photocurable monomer is one of trimethylolpropane triacrylate (TMPTA), trimethylolpropane triacrylate ethoxylate (TMP3EOTA), and pentaerythritol triacrylate (PETA).

[0051] Furthermore, the dispersant is one of the polymer copolymer dispersants BYK111, BYK183, BYK163, BYK180, Sago9090, and Sago9073, and the amount of dispersant added accounts for 2-5 wt% of the photocurable ceramic slurry.

[0052] The photoinitiator is one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), 1-hydroxycyclohexylphenyl methyl ketone (184), and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (819), and the amount of photoinitiator added accounts for 2-4 wt% of the photocurable ceramic slurry.

[0053] Furthermore, in photopolymer 3D printing, the laser power is set to 5-200 mW / cm². 2 The printing layer thickness is 20-50μm, and the extrusion rate and direct writing rate of the photocurable ceramic slurry for each gradient layer are 5-10cm. 3 Photopolymerization printing is performed at speeds of 5-20 mm / s and in the order of solid content gradient (solid content from high to low or from low to high) to form green blanks of multi-material ceramic structural parts with solid content gradient.

[0054] Furthermore, the degreasing temperature was increased from room temperature to 600℃ at a rate of 0.1-0.6℃ / min, and the temperature was maintained at 300℃, 340℃, 400℃, 420℃ and 500℃ for 1-3 hours respectively.

[0055] Preferably, the sintering is carried out in two steps: first, the temperature is raised at 1800°C for 2-4 hours under an inert gas at a heating rate of 5°C / min, and then sintered at 1800°C for 1-2 hours in a spark plasma SPS furnace at a heating rate of 5°C / min.

[0056] Furthermore, the UV-curable ceramic slurry also contains oligomers such as aliphatic polyurethane acrylate or epoxy acrylate, which are used in conjunction with the UV-curing monomer to adjust the viscosity of the slurry and appropriately regulate the degree of UV curing. The volume ratio of the aliphatic polyurethane acrylate or epoxy acrylate oligomer to the UV-curing monomer is 1:9 to 3:7.

[0057] Furthermore, the photocurable ceramic slurry also contains sintering aids; the sintering aids are one or more of yttrium oxide powder (Y2O3 powder), aluminum oxide powder (Al2O3 powder), and magnesium oxide powder (MgO powder), and the amount added corresponds to 2-4 wt% of the photocurable ceramic slurry.

[0058] In some embodiments of the present invention, after hot degreasing of the multi-material ceramic green body based on the above preparation method, no obvious defects are generated at the interface between different materials, and the interface bonding is good, which improves the overall performance of the multi-material ceramic structural parts.

[0059] In some embodiments of the present invention, based on the optimization of the composition, degreasing parameters and gradient structure design by the above method, multi-material ceramic materials can meet the design requirements of complex-shaped ceramic structural parts and high-precision complex-shaped ceramic structural parts, thus making them more suitable for the application of multi-material ceramic structural parts in aerospace, automotive processing, micro-nano devices, semiconductors and other fields.

[0060] Some specific embodiments will be given below, along with detailed descriptions in conjunction with the accompanying drawings.

[0061] Comparative Example 1:

[0062] 1) Dry, grind, and sieve the alumina and silica powders;

[0063] 2) Weigh IBOA, HDDA, and PETA in a volume ratio of 2:5:3. The oligomer is an aliphatic polyurethane acrylate. The volume ratio of the photocurable monomer to the oligomer is set to 1:9. The dispersant is 2wt% BYK111, and the initiator is 3wt% 819. Prepare 40 vol% and 52.5 vol% silica ceramic slurry and alumina ceramic slurry, respectively.

[0064] 3) Using the above slurry as raw material, a multi-material photopolymerization 3D printing machine is used to design a gradient-free structure, import the processing model, and form a green body of a multi-material ceramic structure.

[0065] 4) Degrease the above-mentioned green billets in an exothermic degreasing furnace using an air atmosphere. The heating rate is 0.1℃ / min, and the holding time is 2 hours at 300℃, 340℃, 400℃, 420℃, and 500℃.

[0066] 5) Finally, multi-material ceramic structural parts with controllable microstructure are obtained through high-temperature sintering.

[0067] Comparative Example 2:

[0068] 1) Dry, grind, and sieve the alumina and zirconium oxide powders;

[0069] 2) Weigh ACMO, HDDA and TMP3EOTA in a volume ratio of 3:5:2. The oligomer is epoxy acrylate. The volume ratio of the photocurable monomer to the oligomer is set to 2:8. The dispersant is 3wt% BYK163 and the initiator is 2wt% TPO. Prepare 40vol% and 52.5vol% alumina ceramic slurry and zirconia ceramic slurry respectively.

[0070] 3) Using the above slurry as raw material, a multi-material photopolymerization 3D printing machine is used to design a gradient-free structure, import the processing model, and form a green body of a multi-material ceramic structure.

[0071] 4) Degrease the above-mentioned green billets in an exothermic degreasing furnace using an argon atmosphere. The heating rate is 0.1℃ / min, and the holding time is 2 hours at 300℃, 340℃, 400℃, 420℃, and 500℃.

[0072] 5) Finally, multi-material ceramic structural parts with controllable microstructure are obtained through high-temperature sintering.

[0073] Comparative Example 3:

[0074] 1) Dry, grind, and sieve the silicon carbide and titanium nitride powders;

[0075] 2) Weigh IBOA, DPGDA and PETA in a volume ratio of 1:5:4. The oligomer is aliphatic polyurethane acrylate. The volume ratio of the photocurable monomer to the oligomer is set to 3:7. The dispersant is 3wt% Sago9900, the initiator is 2wt% 819, the plasticizer is PPG200, and the volume ratio of the plasticizer to the photocurable monomer is 2:8. Prepare 40 vol% and 52.5 vol% silicon carbide ceramic slurry and titanium nitride ceramic slurry respectively.

[0076] 3) Using the above slurry as raw material, a multi-material photopolymerization 3D printing machine is used to design a gradient-free structure, import the processing model, and form a green body of a multi-material ceramic structure.

[0077] 4) Degrease the above-mentioned green billets in an exothermic degreasing furnace using an argon atmosphere. The heating rate is 0.1℃ / min, and the holding time is 2 hours at 300℃, 340℃, 400℃, 420℃, and 500℃.

[0078] 5) Finally, multi-material ceramic structural parts with controllable microstructure are obtained through high-temperature sintering.

[0079] Example 1:

[0080] 1) Dry, grind, and sieve the silicon carbide and titanium nitride powders;

[0081] 2) Weigh ACMO, DPGDA, and PETA in a volume ratio of 3:5:2. The oligomer is aliphatic polyurethane acrylate. The volume ratio of the photocurable monomer to the oligomer is set to 1:9. The dispersant is 2wt% Sago9900, the initiator is 4wt% 819, and the plasticizer is PPG200. The volume ratio of the plasticizer to the photocurable monomer is 1.5:8.5. Prepare 40 vol% silicon carbide ceramic slurry and 52.5 vol% titanium nitride ceramic slurry, respectively. Also prepare silicon carbide / titanium nitride composite slurries with solid contents of 42.5 vol%, 45 vol%, 47.5 vol%, and 50 vol%. In the silicon carbide / titanium nitride composite slurry, the mass ratio of silicon carbide powder to titanium nitride powder is 1:1.

[0082] 3) Using the above slurry as raw material, a multi-material photopolymerization 3D printing machine is used to design a gradient structure according to silicon carbide / titanium nitride composite slurry with solid contents of 42.5 vol%, 45 vol%, 47.5 vol%, and 50 vol%, and the slurry is imported into the processing model to form a green body of a multi-material ceramic structure with a gradient content.

[0083] 4) Degrease the above-mentioned green billets in an exothermic degreasing furnace using an argon atmosphere. The heating rate is 0.1℃ / min, and the holding time is 2 hours at 300℃, 340℃, 400℃, 420℃, and 500℃.

[0084] 5) Finally, multi-material ceramic structural parts with controllable microstructure are obtained through high-temperature sintering.

[0085] Example 2:

[0086] 1) Dry, grind, and sieve the silicon carbide and silicon nitride powders;

[0087] 2) Weigh IBOA, HDDA, and PETA in a volume ratio of 2:5:3. The oligomer is aliphatic polyurethane acrylate. The volume ratio of the photocurable monomer to the oligomer is set to 2:8. The dispersant is 2wt% BYK111, the initiator is 2wt% TPO, and the plasticizer is PEG200. The volume ratio of the plasticizer to the photocurable monomer is 2:8. Prepare 40 vol% and 52.5 vol% silicon carbide ceramic slurry and silicon nitride ceramic slurry, respectively. Also prepare 42.5 vol%, 45 vol%, 47.5 vol%, and 50 vol% silicon carbide / silicon nitride composite slurry. The mass ratio of silicon carbide powder to titanium nitride powder in the silicon carbide / titanium nitride composite slurry is 1:1.

[0088] 3) Using the above slurry as raw material, a gradient structure is designed using a multi-material photopolymerization 3D printing machine, the processing model is imported, and a multi-material ceramic structural green body is formed.

[0089] 4) The above-mentioned green billets are degreased in an exothermic degreasing furnace using an argon atmosphere. The heating rate is 0.3℃ / min, and the holding time is 300℃, 340℃, 400℃, 420℃, and 500℃, with a holding time of 3 hours.

[0090] 5) Finally, multi-material ceramic structural parts with controllable microstructure are obtained through high-temperature sintering.

[0091] Example 3:

[0092] 1) Dry, grind, and sieve the silicon nitride and aluminum nitride powders;

[0093] 2) Weigh ACMO, HDDA, and TMP3EOTA in a volume ratio of 3:5:2. The oligomer is aliphatic polyurethane acrylate. The volume ratio of the photocurable monomer to the oligomer is set to 1:9. The dispersant is 2wt% BYK163, the initiator is 2wt% 819, and the plasticizer is DEG. The volume ratio of the plasticizer to the photocurable monomer is 1:9. Prepare 40 vol% and 52.5 vol% silicon carbide ceramic slurry and silicon nitride ceramic slurry, respectively. Also prepare 42.5 vol%, 45 vol%, 47.5 vol% and 50 vol% silicon nitride / aluminum nitride composite slurry. In the silicon carbide / titanium nitride composite slurry, the mass ratio of silicon carbide powder to titanium nitride powder is 1:1.

[0094] 3) Using the above slurry as raw material, a gradient structure is designed using a multi-material photopolymerization 3D printing machine, the processing model is imported, and a multi-material ceramic structural green body is formed.

[0095] 4) Degrease the above-mentioned green billets in an exothermic degreasing furnace using an argon atmosphere. The heating rate is 0.2℃ / min, and the holding time is 300, 340, 400, 420, and 500℃ for 3 hours.

[0096] 5) Finally, multi-material ceramic structural parts with controllable microstructure are obtained through high-temperature sintering.

[0097] The above embodiments and comparative examples were subjected to TG / DSC testing and interface SEM testing, respectively.

[0098] TG / DSC tests were performed at a heating rate of 10℃ / min in the range of 20-600℃.

[0099] like Figure 1 The data shown are the TG / DSC data for comparative examples 1-3. Figure 1 In the figure, 'a' corresponds to the TG / DSC analysis of the multi-material ceramic structural component prepared in air without gradient design and plasticizer, and degreased in air, corresponding to ratio 1. The heat release during the high-temperature degreasing stage is 4.09 mw / mg and 2.23 mw / mg. Figure 1 Figure b corresponds to the multi-material ceramic structural component prepared in Comparative Example 2 with no gradient design, no plasticizer, and degreasing in argon. The heat release during the high-temperature degreasing stage is 0.58 mw / mg and 0.53 mw / mg. Figure 1 In Figure c, the multi-material ceramic structural component prepared by gradient-free design, PPG200 plasticizer and degreasing in argon gas in Comparative Example 3 shows exothermic reactions of 0.23 mw / mg and 0.03 mw / mg during the high-temperature degreasing stage.

[0100] TG / DSC data for ceramic green bodies with different gradient designs in Example 1. TG / DSC tests were performed separately on different layers of the gradient-designed structural component, such as... Figure 2As shown, gradient design can effectively mitigate the heat dissipation differences between different layers.

[0101] Figure 3 SEM images of multi-ceramic splines and complex-shaped ceramic structural components after degreasing, used in Comparative Examples 1-3 and Example 1 with different slurry compositions, degreasing processes, and gradient designs. According to the SEM images, Comparative Example 1... Figure 3 As shown in Figure a, multi-material ceramic structural components prepared without gradient design, without plasticizers, and degreased in air exhibit large cracks and delamination at heterogeneous interfaces; Comparative Example 2 shows... Figure 3 As shown in b, the multi-material ceramic structural component prepared without gradient design, without plasticizer, and degreased in argon gas exhibits only delamination defects at the heterogeneous interface; Comparative Example 3... Figure 3 As shown in c, multi-material ceramic structural components prepared using gradient design, PPG200 plasticizer, and debinding in argon exhibit only minor delamination defects at the heterogeneous interface; implementation examples include... Figure 3 As shown in d, when gradient design, addition of plasticizer, and degreasing in argon gas are performed, no obvious defects are generated at the heterogeneous interface.

[0102] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims and their equivalents, this invention also intends to include these modifications and variations. The above-described embodiments are merely preferred embodiments for fully illustrating the invention, and their scope of protection is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on this invention are all within the scope of protection of this invention, which is defined by the claims.

Claims

1. A method for preparing photopolymer 3D printed multi-material ceramic structural parts, characterized in that, Includes the following steps: (1) Ceramic powder A, mixed ceramic powder, and ceramic powder B are respectively formulated with a photocurable monomer, a dispersant, a photoinitiator, and a low molecular weight plasticizer to prepare a photocurable ceramic slurry, wherein the solid content of ceramic powder A, the mixed ceramic powder, and the ceramic powder B in the corresponding photocurable ceramic slurry changes in a uniform gradient; wherein the mixed ceramic powder is a mixture of ceramic powder A and ceramic powder B; wherein the low molecular weight plasticizer is an aliphatic plasticizer or a phthalic plasticizer with a molecular weight lower than 400 and a decomposition temperature lower than 300℃; the solid content of ceramic powder A, the mixed ceramic powder, and the ceramic powder B in the corresponding photocurable ceramic slurry is 40-60 vol%; at least one photocurable ceramic slurry with a mixed ceramic powder solid content is set according to the difference in solid content between ceramic powder A and ceramic powder B in the corresponding photocurable ceramic slurry, and the solid content difference between two photocurable ceramic slurries with adjacent solid contents is 1-2.5%. vol%; the volume ratio of the low molecular weight plasticizer to the photocurable monomer in the photocurable ceramic slurry is from 1.5:8.5 to 2.5:7.5; both ceramic powder A and ceramic powder B are selected from one of silicon oxide, zirconium oxide, alumina, hydroxyapatite, calcium phosphate, silicon carbide, silicon nitride, aluminum nitride, or titanium nitride, and the materials selected for ceramic powder A and ceramic powder B are different; (2) The photocurable ceramic slurry is used in a multi-material photocurable 3D printing machine to perform integrated photocurable printing according to the solid content gradient of the photocurable ceramic slurry to prepare a green body of a multi-material ceramic structure with a solid content gradient. (3) The green body of the multi-material ceramic structure is degreased and sintered under argon to produce a multi-material ceramic structure; the degreasing temperature is raised from room temperature to 600 ℃ at a rate of 0.1 ~ 0.6 ℃ / min, and held at 300 ℃, 340 ℃, 400 ℃, 420 ℃ and 500 ℃ for 1-3 h respectively.

2. The method for preparing photopolymer 3D printed multi-material ceramic structural parts according to claim 1, characterized in that, The low molecular weight plasticizer is polyethylene glycol, polypropylene glycol, diethylene glycol, or dibutyl phthalate; wherein the molecular weight of the polyethylene glycol and the polypropylene glycol is 200.

3. The method for preparing photopolymer 3D printed multi-material ceramic structural parts according to claim 1, characterized in that, The photocurable monomer is a mixture of monofunctional, difunctional, and multifunctional photocurable monomers; the amount of the photocurable monomer added accounts for 30-50 vol% of the photocurable ceramic slurry. The volume ratio of the monofunctional photocurable monomer to the polyfunctional photocurable monomer is 1:4 to 4:1, and the total volume ratio of the monofunctional and polyfunctional photocurable monomers is 50 vol% of the photocurable monomers. The monofunctional photocurable monomer is one of lauryl acrylate, ethoxyethoxyethyl acrylate, isobornyl acrylate, and acrylomorpholine; the difunctional photocurable monomer is one of 1,6-hexanediol acrylate, tripropylene glycol diacrylate, dipropylene glycol acrylate, propionyl dipentylene glycol acrylate, and 1,9-nonanediol diacrylate; the polyfunctional photocurable monomer is one of trimethylolpropane triacrylate, ethoxytrimethylolpropane triacrylate, and pentaerythritol triacrylate.

4. The method for preparing photopolymer 3D printed multi-material ceramic structural parts according to claim 1, characterized in that, The dispersant is one of the polymer copolymer dispersants BYK111, BYK183, BYK163, BYK180, Sago9090, and Sago9073, and the amount of the dispersant added accounts for 2-5 wt% of the photocurable ceramic slurry. The photoinitiator is one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 1-hydroxycyclohexylphenyl methyl ketone, and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and the amount of the photoinitiator added accounts for 2-4 wt% of the photocurable ceramic slurry.

5. The method for preparing photopolymer 3D printed multi-material ceramic structural parts according to claim 1, characterized in that, The photocurable ceramic slurry further comprises aliphatic polyurethane acrylate or epoxy acrylate, and the volume ratio of the aliphatic polyurethane acrylate or epoxy acrylate to the photocurable monomer is 1:9 to 3:

7.

6. The method for preparing photopolymer 3D printed multi-material ceramic structural parts according to claim 1, characterized in that, The photocurable ceramic slurry also contains sintering aids; The sintering aid is one or more of yttrium oxide powder, aluminum oxide powder, and magnesium oxide powder; The amount of the sintering aid added accounts for 2-4 wt% of the photocurable ceramic slurry.

7. Multi-material ceramic structural parts prepared by the preparation method according to any one of claims 1-6.

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