Photocurable ceramic slurry suitable for ultra-rapid debinding and its preparation method and application

Abstract

The application belongs to the technical field of ceramic additive manufacturing, and particularly relates to a photocurable ceramic slurry suitable for super-fast debinding, a preparation method and application thereof. The slurry comprises 20-60 parts of photosensitive resin monomer, 0.5%-5wt.% of corresponding photoinitiator, 10-50 parts of inert solvent, 30-80 parts of ceramic powder and 0.5%-5wt.% of corresponding dispersant. The key lies in using a specific inert solvent with a boiling point range of 180-250 DEG C, a relative volatility less than 0.1 at 25 DEG C and not participating in photocuring. In the debinding process, the solvent is preferentially decomposed and volatilized to form connected initial exhaust channels in the green body, thereby realizing the spatial and temporal separation of the 'volatilization-decomposition' stage, so that the resin decomposition gas can be quickly discharged. The application effectively solves the problems of long debinding cycle and easy cracking of traditional photocurable ceramic green body, and is particularly suitable for high-performance ceramic systems such as silicon nitride, silicon carbide and aluminum nitride, and finally high-density and high-strength ceramic products can be obtained.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology for ceramic materials, specifically to a photocurable ceramic slurry suitable for ultra-fast degreasing, its preparation method, and its application. Background Technology

[0002] Photopolymerization 3D printing technologies (such as stereolithography (SLA) and digital light processing (DLP)) have become a research and application hotspot in ceramic additive manufacturing due to their unique advantages in forming high-precision, complex-structured ceramic parts. The key to this technology lies in preparing ceramic slurries that combine high solids content, good rheological properties, and suitable curing depth.

[0003] However, traditional photocurable ceramic slurries face severe challenges in the subsequent pyrolysis (debinding) process. The photosensitive resin in the slurry, acting as a temporary binder, needs to be completely decomposed and released at high temperatures. This process generates a large amount of gas, which, if not released promptly and smoothly from the dense green body, can easily create localized high pressure, leading to blistering, cracking, or even complete fragmentation of the green body. To avoid these defects, existing processes often resort to extremely slow heating rates and long holding times to ensure stable gas release, resulting in a debinding cycle that can last for tens or even hundreds of hours, severely restricting production efficiency and cost.

[0004] To shorten the degreasing cycle and ensure the yield, existing technologies mainly attempt to optimize the degreasing process and improve the slurry formulation, but both have limitations: (1) Optimize the degreasing process: By precisely controlling the heating curve and introducing multi-stage heat preservation or complex atmospheres (such as vacuum / protective gas switching), it is attempted to safely exhaust the gas without changing the intrinsic properties of the material. For example, the invention patent (CN202311585376.9) reduces the oxidation degree of aluminum nitride ceramics and shortens the degreasing time by controlling the partial pressure of oxygen and nitrogen in the furnace. Although such methods have certain effects, the process is complex, the equipment requirements are high, and the improvement in degreasing speed is limited. In essence, it is still a conservative and passive solution that adapts to the exhaust characteristics of the material.

[0005] (2) Improved slurry formulation: This mainly focuses on increasing solids content, improving dispersibility, or adjusting the resin system to enhance green strength. For example, adding specific functional group monomers can improve the adhesion of the slurry to the substrate, or optimizing the resin and diluent combination can yield a slurry with high solids content and low viscosity. Other methods aim to prepare slurries with high solids content (e.g., 55 vol% or more) to obtain high-density greens. While these improvements help with molding, they do not fundamentally solve the problem of concentrated gas emission during the resin decomposition stage. High-solids-content greens are denser, which can sometimes exacerbate venting resistance. More importantly, these solutions fail to proactively build efficient venting channels inside the green; gas emission still relies on the fine pores left after the slow thermal decomposition of the resin matrix, and the bottleneck of degreasing efficiency remains.

[0006] Recently, some studies have also attempted to actively improve the degreasing and venting process by adding non-reactive diluents or pore-forming agents to the slurry. For example, some works have adopted... γ -Gastrolide (GVL) was used as a diluent for high-solids-content (67 vol%) silica slurries, while other studies have used polypropylene glycol (PPG) as an additive for silicon nitride slurries. These approaches have demonstrated the feasibility of introducing volatile components to pre-form venting channels and have achieved some success. However, they still have significant limitations, especially when the target is high-performance ceramic systems with complex optical properties (such as dark colors and high light absorption) and high sintering activity (such as nitrides and carbides): For small-molecule solvents such as GVL, the research systems (e.g., SiO2) are typically light-colored, low-absorbance powders, with relatively relaxed requirements for curing depth. However, for dark-colored ceramics such as silicon nitride and silicon carbide, to ensure sufficient curing depth, extremely precise control of the absorbance and volatility stability of each component in the slurry is necessary. Existing methods lack precise definition and control of key solvent properties (such as relative volatility), making it difficult to guarantee ultra-stable operation during long-term printing and to ensure optimal and gradual evaporation in the initial degreasing stage to build a uniform exhaust network.

[0007] For polymer additives such as PPG, as high molecular weight compounds, they do not have a defined boiling point and are mainly removed over a wide temperature range through thermal decomposition. This characteristic means that their decomposition temperature range easily overlaps with that of photosensitive resins, making it impossible to achieve clear and controllable separation between "pre-pore building" and "subsequent venting" in the degreasing stage. This results in a narrow process window and may introduce new cracking risks due to concentrated gas release. Furthermore, their high molecular weight and viscosity also limit their addition amount in high-solids-content slurries.

[0008] More importantly, none of the above solutions provide a universal solution to systematically resolve the core contradiction in printing high-performance ceramics: simultaneously ensuring "ultra-stable slurry," "highly controllable volatilization / decomposition behavior," and "strict separation of the degreasing stage." This contradiction is particularly pronounced for materials such as silicon nitride and silicon carbide. Summary of the Invention

[0009] To address the technical bottlenecks in existing photocurable ceramic green body degreasing processes, which are lengthy and prone to cracking due to internal gas accumulation, this invention aims to provide a novel photocurable ceramic slurry, its preparation method, and its applications. This technical solution aims to start from the material formulation design stage, introducing a specific inert solvent with precisely designed volatility characteristics. While ensuring excellent slurry printing performance, it pre-constructs efficient venting channels within the green body, thereby achieving rapid and safe degreasing of ceramic products, significantly shortening the production cycle and improving the yield.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a photocurable ceramic slurry suitable for ultra-rapid degreasing, the slurry comprising the following components in parts by mass: Photosensitive resin monomer: 20~60 parts, as the main body for forming the three-dimensional network structure, providing the initial strength of the green body; Photoinitiator: accounting for 0.5% to 5% of the mass of the photosensitive resin monomer, used to initiate the photopolymerization reaction; Inert solvent: 10-50 parts; Ceramic powder: 30-80 parts; Dispersant: accounting for 0.5% to 5% of the mass of the ceramic powder, used to ensure stable dispersion of the ceramic powder in the system.

[0011] The inert solvent does not participate in the photocuring crosslinking reaction; the boiling point of the inert solvent is in the range of 180℃ to 250℃ and its relative volatility at 25℃ is less than 0.1 with reference to n-butyl acetate. Specifically, the inert solvent has a relative volatility of less than 0.1 at 25°C (with butyl acetate as 1), and its chemical properties are stable, not participating in the photocuring crosslinking reaction. Strictly limiting the volatility of the inert solvent is crucial to ensuring the slurry maintains stable viscosity and does not degrade in performance during long-term printing. The core function of the inert solvent is that, during subsequent green body debinding, it is removed preferentially from the thermal decomposition temperature range of the photosensitive resin monomers through physical evaporation. This preferential evaporation behavior can generate and form a large number of interconnected initial venting channels in situ within the still-tough resin and ceramic framework. Furthermore, the boiling point of the inert solvent is preferably between 180°C and 250°C. A boiling point that is too low may cause slight solvent evaporation during printing, affecting the stability of the slurry; a boiling point that is too high may cause its evaporation stage to overlap with the resin decomposition stage, weakening the pre-pore-forming effect.

[0012] Furthermore, the slurry of the present invention also has the following key performance parameters: its solid volume fraction is 45%~60%, and it has a 30 s [response time missing]. -1 The viscosity at the shear rate is 1.5~15 Pa·s, and the curing depth is not less than 30 μm. These parameters together ensure that the slurry has good flow and spreadability at high solids content, is suitable for layer-by-layer printing processes, and has sufficient single-layer curing capability.

[0013] Preferably, the inert solvent includes one or more of diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, tripropylene glycol methyl ether, and propylene glycol phenyl ether. More preferably, the inert solvent is a diethylene glycol ether or tripropylene glycol methyl ether. This boiling point range and the preferred solvent type together ensure that the solvent can fully evaporate within a relatively narrow and controllable temperature window in the early stage of degreasing, thereby achieving a clear separation from the resin decomposition stage.

[0014] Furthermore, the ceramic powder is one or more combinations of nitride ceramics (such as silicon nitride), carbide ceramics (such as silicon carbide), or boride ceramics. To address the issue of strong ultraviolet light absorption in some dark-colored ceramic powders, the ceramic powder can undergo surface coating modification to reduce its ultraviolet light absorption rate, thereby ensuring the overall curing depth of the slurry. To obtain a higher green body density, the ceramic powder can be composed of single-size powder or two or more powders of different sizes graded together.

[0015] Furthermore, the photosensitive resin monomer includes one or more combinations of polyurethane acrylate, aliphatic polyurethane acrylate, aromatic polyurethane acrylate, modified polyurethane acrylate, epoxy acrylate, polyester acrylate, pentaerythritol tetraacrylate ethoxylate, trimethylolpropane triacrylate, 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, isobornyl acrylate, and hydroxyethyl methacrylate.

[0016] Furthermore, the photoinitiator is a free radical photoinitiator selected from one or more of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (819), 2-isopropylthioxanthone (ITX), 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone (907), and 1-hydroxycyclohexylphenyl ketone (184); preferably, the photoinitiator is diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide.

[0017] Furthermore, the dispersant is a polymeric dispersant selected from one or more of BYK-111, BYK-108, BYK-180, BYK-190, KOS110, KOS163, KOS2400, TEGO Dispers 655, and Solsperse 41000; preferably, the dispersant is a block copolymer dispersant containing anchoring groups and solvation chains.

[0018] Secondly, this invention provides a method for preparing the aforementioned photocurable ceramic slurry suitable for ultra-fast degreasing. The method includes the following steps: S1. Mixing and ball-milling ceramic powder, dispersant, and a portion of inert solvent to obtain a uniform premix; S2. Stirring and degassing the premix with photosensitive resin monomer, the remaining inert solvent, and photoinitiator under vacuum conditions to finally obtain the slurry with highly uniform components and extremely low bubble content. This method is simple and easy to scale up. It should be noted that the method of adding the inert solvent is adjusted according to the viscosity of the slurry: if the slurry viscosity is relatively high, all of it can be added in S1. If the slurry viscosity is relatively low, a portion can be added in S1, and the remainder added in S2.

[0019] Furthermore, S1 specifically includes: ball milling for 1 to 6 hours using a planetary ball mill or a horizontal ball mill; S2 specifically includes: mixing in a planetary vacuum gravity mixer, stirring at 300 to 1500 rpm for 1 to 15 minutes, and simultaneously performing vacuum degassing.

[0020] Thirdly, the present invention provides the application of the above-mentioned photocurable ceramic slurry suitable for ultra-fast degreasing in the preparation of ceramic green bodies and ceramic products.

[0021] Fourthly, this invention provides a ceramic green body, which is formed by photopolymerization 3D printing from a photopolymerization ceramic slurry suitable for ultra-fast debinding, as described above. It is understood that the method for preparing this ceramic green body involves using the aforementioned photopolymerization ceramic slurry suitable for ultra-fast debinding, and then curing it layer by layer using photopolymerization 3D printing technologies such as stereolithography (SLA) or digital light processing (DLP) to directly form a ceramic green body with a complex three-dimensional structure. Because the slurry has a curing depth of not less than 30 μm, strong interlayer bonding and good dimensional accuracy are ensured.

[0022] Fifthly, the present invention provides a ceramic product obtained by degreasing and sintering the above-mentioned ceramic green body.

[0023] Sixthly, the present invention provides a method for preparing a ceramic product. The method includes: (a) using the aforementioned ceramic green body; (b) degreasing the green body: under air or an inert atmosphere, first heating to 150°C to 250°C at a rate of 1 to 5°C / min and holding at that temperature for 0.2 to 2 hours, during which the inert solvent preferentially and fully evaporates, forming a permeable initial pore network in the green body; then continuing to heat to 400°C to 600°C at the same or different heating rates, during which the photosensitive resin decomposes, and the generated gas can be quickly and smoothly discharged through the existing pore network, thereby avoiding gas pressure accumulation; (c) finally sintering the degreased green body at high temperature to densify it, thereby obtaining the final ceramic product.

[0024] Compared with the closest prior art, the beneficial effects of the present invention are as follows: (1) Achieving essential acceleration and precise separation of stages in the degreasing process: This invention introduces a small molecule ether inert solvent with low relative volatility (<0.1) and suitable boiling point (180~250℃), achieving clear spatiotemporal separation of "physical volatilization" and "thermal decomposition" in the internal stages of the degreasing process from a material design perspective. The solvent is preferentially and gradually removed through volatilization in the low-temperature stage, actively constructing a uniform "pre-set highway" exhaust network for the subsequent high-temperature resin decomposition stage, allowing a large amount of decomposition gas to diffuse rapidly. This allows the degreasing heating rate to be increased to 1~5℃ / min while ensuring the integrity of the green body. Compared with the traditional process that relies on the slow pyrolysis of resin to create pores, the total degreasing time can be shortened by more than 100%, or even by several times.

[0025] (2) Significantly improved degreasing yield of thick-walled and complex-structured green bodies: The initial pore network formed by the evaporation of inert solvents, thanks to the low volatility and uniformity of the solvent, has a more uniform distribution and excellent connectivity. It can efficiently release the gas pressure generated by the concentrated decomposition of resin, just like a pre-laid drainage system, fundamentally suppressing defects such as blistering and interlayer cracking caused by local high pressure. Especially for thick-walled or complex-structured components of high-performance ceramics such as silicon nitride, the yield can be significantly improved.

[0026] (3) Ensuring both excellent printing performance and exceptional paste stability at high solids content: This invention ensures exceptional time stability of the paste in the printing tank by strictly limiting the low relative volatility of the inert solvent. Its viscosity does not change significantly over time due to solvent evaporation, guaranteeing the reliability of long-term, high-precision printing. Simultaneously, at a high solids volume fraction of 45%–60%, through component optimization, the paste viscosity can still be controlled at 1.5–15 Pa·s (30 s⁻¹). -1 It ensures a curing depth of not less than 30μm, thereby simultaneously meeting the requirements for high densification sintering and good forming accuracy and green strength.

[0027] (4) Specific effectiveness and designability for high-performance ceramic systems: This technical solution is particularly suitable for high-performance ceramic systems such as nitrides, carbides, and borides. The ether-based inert solvent selected in this invention has a molecular polarity that can be adjusted over a wide range, enabling excellent matching with various photosensitive resin monomers of strong polarity, moderate polarity, and non-polarity, forming a highly uniform and stable slurry system. This distinguishes it from specific strong polar solvents (such as...). γ One of the core advantages of using valerol (GVL) or high molecular weight polymers (such as polypropylene glycol PPG) is that by selecting ether solvents with specific boiling points, the evaporation stage and the resin decomposition stage can be precisely matched. For dark, high-absorbency ceramic powders (such as some borides), this solution can be combined with powder surface modification technology to effectively ensure the curing depth and expand the material application range of photopolymerization molding technology. In addition, by adjusting the type and content of the solvent, the size and connectivity of the formed pore network can be flexibly controlled, thereby precisely matching the thermal decomposition characteristics and sintering process requirements of different ceramic materials, which has broad and in-depth application prospects. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced below; obviously, the drawings described below are some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0029] Figure 1 This is a flowchart illustrating the overall process of ceramic slurry preparation and ceramic product preparation according to the present invention.

[0030] Figure 2 This is a schematic diagram comparing the degassing principle of a traditional slurry preform (left) and the slurry preform of this invention (right) during the degreasing process.

[0031] Figure 3 This is a viscosity-shear rate curve of the slurry prepared in Example 1 of the present invention.

[0032] Figure 4 This is a comparison chart of the thermogravimetric (TG) and differential thermogravimetric (DTG) curves of the green body during the degreasing process of the traditional comparative example (left) and Example 1 of the present invention (right).

[0033] Figure 5 This is a stress-strain curve of the silicon nitride ceramic prepared in Example 1 of the present invention.

[0034] Figure 6 This is a comparison image of the cross-section of a green blank after heat treatment at 250°C, showing a traditional comparative example (left) and an embodiment 1 of the present invention (right).

[0035] Figure 7 This is a degreasing process curve diagram of Example 1 showing that the green body does not crack under different degreasing processes.

[0036] Figure 8 This is a photograph of a complex-structured ceramic green body prepared using the method of this invention after degreasing. Detailed Implementation

[0037] In view of the background technology, in order to fundamentally reconcile the contradictions between "high solids content of slurry and printing stability" and "green strength" and "rapid degreasing and safety", this invention provides a photocurable ceramic slurry that can start from the material design source, introduce inert components with precise and controllable volatility characteristics, and actively construct an internal exhaust network while ensuring good printability (such as curing depth of not less than 30μm) and green strength, thereby achieving ultra-fast and high-yield degreasing. This has become a key technical problem that urgently needs to be solved to promote the efficient and large-scale application of this technology.

[0038] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter range described in the present invention. Reasonable variations derived therefrom are still within the protection scope of the claims of the present invention.

[0039] It should be understood that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses. Furthermore, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not intended to limit the order of the method steps or define the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0040] It should be noted that the endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges. These numerical ranges should be considered as specifically disclosed herein. Process equipment or apparatus not specifically specified in the following embodiments employs conventional equipment or apparatus in the art.

[0041] 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 specific embodiments. The following embodiments are intended to illustrate the invention, not to limit it. Unless otherwise specified, all reagents and instruments used in this invention are commercially available.

[0042] Reference Figure 1 This invention provides a method for preparing a light-curing ceramic slurry suitable for ultra-fast degreasing, from the preparation of ceramic green bodies to the final production of ceramic products.

[0043] The formulation of the photocurable ceramic slurry suitable for ultra-fast degreasing is as follows (all parts by weight): 20-60 parts of photosensitive resin monomer, 10-50 parts of inert solvent, and 30-80 parts of ceramic powder; it also includes 0.5%-5% of photoinitiator by weight of the photosensitive resin monomer and 0.5%-5% of dispersant by weight of the ceramic powder.

[0044] The method specifically includes: S1. Mix ceramic powder, dispersant and all or part of inert solvent and ball mill to obtain premix.

[0045] S2. The premixed material is stirred and mixed with the photosensitive resin monomer, photoinitiator and the remaining inert solvent under vacuum and degassed to obtain a photocurable ceramic slurry suitable for ultra-fast degreasing (referred to as ceramic slurry).

[0046] S3. The ceramic slurry is solidified layer by layer using photopolymerization 3D printing technology to obtain a ceramic green body (i.e., a ceramic blank).

[0047] S4. The ceramic green body is degreased and sintered to obtain ceramic products.

[0048] Reference Figure 2 Traditional photocurable ceramic slurries face severe challenges during the subsequent pyrolysis (debinding) process. The photosensitive resin in the slurry, acting as a temporary binder, needs to be completely decomposed and released at high temperatures. This process generates a large amount of gas, which, unable to escape from the dense interior of the green body in a timely and smooth manner, can easily create localized high pressure, leading to blistering, cracking, or even complete fragmentation of the green body.

[0049] The formulation of the photocurable ceramic slurry suitable for ultra-fast degreasing provided by this invention includes an inert solvent. During the degreasing process of the green body, the solvent is removed preferentially from the thermal decomposition temperature range of the photosensitive resin monomer through physical volatilization. This results in the in-situ generation and formation of a large number of interconnected initial venting channels within the still resilient resin and ceramic framework. This further avoids bubbling and cracking caused by high pressure.

[0050] In the method provided by this invention, a photograph of the ceramic green body after degreasing treatment is shown below. Figure 8 As shown in the image, the sample is intact with a smooth surface and no cracks.

[0051] Example 1: Preferred embodiment using silicon nitride ceramic as an example This embodiment provides a method for preparing photocurable silicon nitride ceramic slurry and its products suitable for ultra-fast degreasing.

[0052] Slurry preparation: Weigh out the particles with a particle size D according to the mass fraction. 50 0.5μm α - 64 parts of silicon nitride powder, D 50 6 parts of 0.5μm yttrium oxide, D 50 The mixture consisted of 2 parts of 0.2μm alumina (72 parts in total), 10 parts of diethylene glycol ethyl ether (boiling point 202℃, relative volatility approximately 0.02), and 1.5 parts of dispersant BYK-111. All three components were placed in a horizontal ball mill and ball-milled at 200 r / min for 4 hours to obtain a homogeneous premix.

[0053] Add 20 parts of photosensitive resin monomer (of which aliphatic polyurethane acrylate and 1,6-hexanediol diacrylate are mixed in a 1:1 mass ratio) and 0.5 parts of photoinitiator TPO to the premix. Transfer all materials into a planetary vacuum gravity mixer and stir at 900 rpm for 3 minutes while maintaining a vacuum of -0.05 MPa to remove air bubbles, finally obtaining slurry A1.

[0054] Performance testing: The solid volume fraction of slurry A1 was measured to be 46% at 30 s. -1 The viscosity at the shear rate is 3.8 Pa·s (e.g. Figure 3 As shown in the figure, the curing depth was measured to be 55 μm using the direct measurement method.

[0055] A comparison of the thermogravimetric (TG) and differential thermogravimetric (DTG) curves of the green body during the degreasing process in Example 1 of this invention (right) and the conventional comparative example (left) is shown in the figure below. Figure 4 As shown, the thermogravimetric curve of degreasing of the green body in this embodiment is smoother, and the removal of inert components and decomposition of photosensitive resin proceed smoothly over a wider temperature range.

[0056] Green body preparation and debinding: Slurry A1 was imported into a DLP printer (wavelength 405 nm), and the single-layer exposure time was set to 20 seconds with a layer thickness of 25 μm to print a standard bending strength test green body (size: 3 mm × 4 mm × 45 mm). The green body was then placed in an air atmosphere box oven for debinding (process curve as shown). Figure 6 (As shown in curve 5): First, the temperature was increased to 250℃ at a rate of 5℃ / min and held for 15 min. Then, the temperature was increased to 430℃ at the same rate and held for 15 min. Finally, the temperature was increased to 550℃ at a rate of 5℃ / min and held for 30 min. The total degreasing time (including heating and holding) was recorded as 2.8 h. After degreasing, the green body was intact and had no visible cracks. Figure 7 As shown.

[0057] Sintering and Ceramic Mechanical Properties: The degreased green body was heated to 1300℃ in a vacuum environment at a rate of 5℃ / min and held for 0.5 hours, followed by a rate of 1℃ / min to 1800℃ and a holding time of 1 hour to obtain dense silicon nitride ceramic. The flexural strength of the sintered body was measured to be 700 MPa using the three-point bending method (e.g., ...). Figure 5 (As shown).

[0058] Example 2: Silicon carbide ceramic system This embodiment provides a method for preparing silicon carbide ceramic slurry and its products with high solid content.

[0059] Slurry preparation: Weigh out the particle size D 50 77 parts of 10μm silicon carbide powder, D 50 Three parts of 1μm diamond powder (80 parts in total), 10 parts of diethylene glycol butyl ether, and 1.5 parts of dispersant KOS163 were placed in a planetary ball mill and ball-milled at 300 r / min for 5 hours to obtain a premix.

[0060] 25 parts of photosensitive resin monomer (1,6-hexanediol diacrylate and trimethylolpropane triacrylate mixed at a mass ratio of 1:1) and 0.5 parts of photoinitiator 819 were added to the premix. The mixture was stirred at 600 rpm for 5 minutes in a planetary vacuum gravity mixer while maintaining a vacuum of -0.02 MPa for degassing to obtain slurry A2.

[0061] Performance testing: The solid volume fraction of slurry A2 was measured to be 57%, and the viscosity was 4.2 Pa·s @ 30s. -1 The curing depth is 42μm.

[0062] Green body preparation and debinding: A DLP printer (wavelength 405 nm) was used, with a single-layer exposure time of 30 seconds and a layer thickness of 30 μm to print the green body. Debinding was performed under a nitrogen protective atmosphere: the temperature was increased to 220℃ at a rate of 5℃ / min and held for 15 minutes, followed by increasing the temperature to 500℃ at the same rate and holding for 1 hour. The total debinding time was approximately 3 hours, and the green body remained intact without cracks.

[0063] Sintering and Ceramic Mechanical Properties: Silicon particles with a diameter of 1 mm were placed on the surface of the degreased green body. The body was then subjected to reaction sintering in a vacuum environment, with the temperature increased to 1700℃ at a rate of 5℃ / min and held for 1 hour to obtain silicon carbide ceramic. Its three-point bending strength was 343 MPa.

[0064] Example 3: Aluminum nitride ceramic system This embodiment demonstrates an aluminum nitride ceramic slurry suitable for high thermal conductivity applications and its rapid degreasing effect.

[0065] Slurry preparation: Weigh out the particle size D 50 58 parts of 1.0 μm aluminum nitride (AlN) powder, D 50 Two parts of 0.5 μm yttrium oxide (as a sintering aid, totaling 60 parts of ceramic powder), 15 parts of propylene glycol phenyl ether, and 0.5 parts of TEGO Dispers 655 dispersant were used. The mixture was ball-milled horizontally at 150 r / min for 2 hours.

[0066] Add 30 parts of photosensitive resin monomer (epoxy acrylate and isoborneol acrylate mixed at a mass ratio of 1:1) and 0.5 parts of photoinitiator TPO. Stir in a planetary vacuum gravity mixer at 1200 rpm for 2 minutes with a vacuum degree of -0.05 MPa to obtain slurry A3.

[0067] Performance testing: Slurry A3 has a solid volume fraction of 48% and a viscosity of 2.9 Pa·s @ 30s. -1 The curing depth is 110μm. The use of light-colored aluminum nitride powder ensures a high curing depth.

[0068] Green body preparation and debinding: A DLP printer was used, with a single-layer exposure time of 10 seconds and a layer thickness of 75 μm. Debinding process: The temperature was increased to 200℃ at 5℃ / min and held for 15 minutes, then increased to 450℃ at 5℃ / min and held for 45 minutes. The total debinding time was approximately 2.5 hours, and the green body remained intact.

[0069] Sintering and ceramic mechanical properties: Under the protection of flowing nitrogen atmosphere, the aluminum nitride ceramic was sintered at 1850℃ at a rate of 5℃ / min and held for 2 hours. The resulting aluminum nitride ceramic had a thermal conductivity of 170 W / (m·K) and a three-point bending strength of 320 MPa.

[0070] Example 4: Surface-modified boron carbide ceramic system This embodiment verifies that after surface modification of high light-absorbing carbides, combined with a specific solvent, good printing and degreasing effects can be achieved.

[0071] Slurry preparation: Powder pretreatment: Weigh the particle size D 50 Eighty parts of boron carbide (B4C) powder with a thickness of 2.0 μm were used. To reduce its strong absorption of ultraviolet light, a process similar to that in Example 5 was employed to coat the powder surface with an amorphous silica (SiO2) modification layer with a thickness of approximately 30 nm, resulting in a light gray modified B4C composite powder. It should be noted that, since the modification layer is very thin, it can be ignored in the calculation of the powder content.

[0072] Mixing and pulping: Weigh 80 parts of the above modified B4C composite powder, and place it together with 10 parts of diethylene glycol methyl ether and 0.5 parts of dispersant BYK-180 in a horizontal ball mill. Ball mill at 220 r / min for 6 hours to obtain a premix.

[0073] 32 parts of photosensitive resin monomer (aromatic polyurethane acrylate and 1,6-hexanediol diacrylate mixed at a mass ratio of 3:1) and 0.5 parts of photoinitiator 819 were added to the premix. The mixture was stirred under planetary vacuum (1100 rpm, 6 minutes, vacuum degree -0.06 MPa) to obtain slurry A4.

[0074] Performance testing: Slurry A4 has a solid volume fraction of 45% and a viscosity of 7.2 Pa·s @ 30s. -1 The curing depth is 70μm. Surface coating modification significantly improves the light absorption of dark boron carbide powder, enabling the curing depth to meet printing requirements.

[0075] Green body preparation and debinding: A DLP printer (wavelength 405 nm) was used, with a single-layer exposure time of 25 seconds and a layer thickness of 50 μm to print the green body. Debinding was performed under flowing argon protection: the temperature was increased to 180℃ at 3℃ / min and held for 1 hour, followed by an increase to 420℃ at 3℃ / min and held for 1.5 hours. The total debinding time was approximately 4.7 hours, and the green body remained intact without cracks or deformation.

[0076] Sintering and Ceramic Mechanical Properties: The degreased green body was placed in a vacuum hot-pressing sintering furnace and held at 2000℃ and 30MPa pressure for 1 hour to obtain dense boron carbide ceramic. Its Vickers hardness reached 32 GPa, and its three-point bending strength was 380MPa.

[0077] Comparative Example 1: Without inert solvents Slurry preparation: Except for the absence of any inert solvent, the composition is the same as the core ceramic component of Example 1: 72 parts silicon nitride-based powder and 1.5 parts dispersant BYK-111. To attempt to achieve a workable viscosity, the resin monomer was increased to 25.5 parts, and the photoinitiator TPO was correspondingly increased to 0.64 parts. Slurry D1 was prepared using the same horizontal ball milling and planetary vacuum stirring process as in Example 1.

[0078] Performance and Results: The viscosity of slurry D1 was too high (>50 Pa·s @ 30s). -1 The resin has extremely poor fluidity and cannot effectively level itself within the printing chamber, making normal printing difficult. The barely formed green body, when subjected to the same degreasing procedure as in Example 1 (i.e., heating at 5°C / min to 250°C and holding for 15 min, then heating at 5°C / min to 430°C and holding for 15 min), bursts around the second holding stage (approximately 430°C), indicating complete degreasing failure. This demonstrates that the lack of a pre-formed venting channel by an inert solvent prevents the gas generated by concentrated resin decomposition from escaping.

[0079] Comparative Example 2: Using a highly volatile solvent (replaced with ethyl acetate) Slurry preparation: The diethylene glycol ethyl ether in Example 1 was replaced with an equal mass of ethyl acetate (boiling point 77°C, relative volatility about 4.0), while the other components and processes remained unchanged, to obtain slurry D2.

[0080] Performance and Results: The initial viscosity of slurry D2 was 3.2 Pa·s @ 30s. -1 However, after standing in the printing tank for 30 minutes, the viscosity increased to 18 Pa·s @ 30s due to rapid solvent evaporation. -1The above factors lead to uneven material distribution during printing, resulting in defects such as streaks on the surface of the green body. When this poorly shaped green body is degreased, in the initial stage of the process (during a temperature increase of 5℃ / min to 250℃, within the range of approximately 80~120℃), the green body experiences severe bubbling and deformation due to rapid solvent vaporization, subsequently leading to structural disintegration and cracking. This indicates that highly volatile solvents damage the stability of the slurry and the structural integrity during the initial stage of degreasing.

[0081] Comparative Example 3: Using a polymerizable reactive diluent (replaced with styrene) Slurry preparation: The inert solvent in Example 1 was replaced with an equal mass of styrene that can participate in free radical copolymerization to obtain slurry D3.

[0082] Performance and Results: Slurry D3 can be printed, but the cured green body exhibits high internal stress and brittleness. During debinding, because styrene has polymerized into the three-dimensional network structure, it cannot preferentially volatilize and create pores at low temperatures. When using the same debinding procedure as in Example 1, the green body fractures brittlely during the heating process to higher temperatures (e.g., towards 550°C) because the gases generated by resin decomposition cannot escape. This confirms that the solvent's "non-participation in the photocuring crosslinking reaction" is a necessary prerequisite for it to perform its "pre-pore-forming" function during debinding.

[0083] Comparative Example 4: Using GVL as a diluent This comparative example aims to verify, if the methods mentioned in the prior art are used... γ How do the overall performance and final effect of replacing the specific ether solvent selected in this invention with valerolactone (GVL) by mass, under completely identical formulation and process conditions, compare?

[0084] Slurry preparation: Weigh out the same ceramic powder as in Example 1 according to the mass fractions. α - 64 parts silicon nitride, 6 parts yttrium oxide, 2 parts aluminum oxide), replace 10 parts diethylene glycol ethyl ether by mass with γ -Velolactone (GVL, boiling point 207℃), dispersant BYK-111 1.5 parts. The three components were placed in a horizontal ball mill and ball-milled at 200 r / min for 4 hours to obtain a homogeneous premix. The same photosensitive resin monomer as in Example 1 (16 parts, aliphatic polyurethane acrylate and HDDA mixed in a 1:1 ratio) and photoinitiator TPO (0.5 parts) were added to the premix. The mixture was stirred at 900 rpm for 3 minutes in a planetary vacuum gravity mixer while maintaining a vacuum of -0.05 MPa for degassing to obtain slurry D4.

[0085] Performance testing: Slurry stability: The solid volume fraction of slurry D4 was measured to be approximately 46% at 30 s. -¹The initial viscosity at the shear rate was 3.6 Pa·s, but after 4 hours of static simulation in the printing tank, the viscosity increased to 5.1 Pa·s @30s. -1 .

[0086] Curing performance: Under the same exposure parameters (20 seconds, 405 nm), the curing depth was measured to be 48 μm, which meets the basic requirements, but is lower than the 55 μm of Example 1.

[0087] Green body degreasing and results: The printed green body was processed using the same degreasing procedure as in Example 1. Microscopic observation of the degreased green body revealed internal microcracks.

[0088] Sintering and Properties: The degreased green body was sintered using the same process as in Example 1. The average three-point flexural strength of the resulting silicon nitride ceramic was 580 MPa, significantly lower than the 700 MPa of Example 1.

[0089] Comparative Example 5: Using PPG as an additive This comparative example aims to simulate and compare the schemes in the literature that use polypropylene glycol (PPG) as a non-reactive additive to verify its impact on slurry properties and the degreasing process.

[0090] Slurry Preparation: The formulation of Example 1 was adjusted to simulate the introduction of PPG. Maintaining the total amount of ceramic powder (72 parts) and the proportion of photoinitiator, the amount of photosensitive resin monomer was reduced to 15 parts, and an additional 5 parts of polypropylene glycol (PPG) with a molecular weight of approximately 1000 were added to make the total amount of organic matter (resin monomer + PPG + inert solvent) comparable to that of Example 1. The formulation was: 72 parts ceramic powder, 15 parts resin monomer, 5 parts PPG, 10 parts diethylene glycol ethyl ether, 1.5 parts dispersant BYK-111, and 0.5 parts photoinitiator TPO. Slurry D5 was prepared using the same ball milling, mixing, and degassing process as in Example 1.

[0091] Performance testing: The viscosity of slurry D5 increased significantly, reaching a high level at 30 s⁻¹. - ¹The shear rate was 8.2 Pa·s. Under the same exposure parameters, the curing depth decreased significantly to 25 μm, failing to meet the printing requirements. Ultimately, a 15 μm slice layer thickness was used for printing.

[0092] Green body degreasing and results: Due to the low strength of the green body, a more conservative degreasing process was adopted (heating at 2℃ / min to 200℃ and holding for 2 hours, then heating at 1℃ / min to 500℃ and holding for 2 hours), with a total degreasing time of 10.5 hours. After degreasing, the green body still showed obvious interlayer separation and deformation.

[0093] Sintering and performance: The degreased green body has severe defects, making it impossible to perform effective sintering to obtain complete ceramic parts that can be tested.

[0094] It should be noted that the resin monomers used in Comparative Examples 1 to 5 are all photosensitive resin monomers.

[0095] Table 1 Comparison of ceramic slurry properties, mechanical properties and effects of photocured ceramics in the examples and comparative examples

[0096] The comparison between the above embodiments and comparative examples clearly shows that the photocurable ceramic slurry and method provided by the present invention, by introducing an ether-based inert solvent with a specific low relative volatility (<0.1) and a suitable boiling point range (180~250℃), successfully coordinates the core contradiction in the printing and debinding process of high-solids-content ceramic slurry. Examples 1-4 all achieved rapid debinding (heating rate 1~5℃ / min) in different ceramic systems (Si3N4, SiC, AlN, B4C) and obtained high-strength, dense sintered bodies (flexural strength 320~700 MPa), which fully demonstrates the universality and effectiveness of the technical solution of the present invention.

[0097] Crucially, the comparative results reinforce the non-obviousness and technological advancement of the present invention from the opposite perspective: Comparative Examples 1 to 3 show that the "presence", "low volatility" and "non-reactivity" of the inert solvent are all indispensable, otherwise it will directly lead to printing failure, degreasing cracking or preform damage.

[0098] Comparative Examples 4 and 5 directly address the closest existing technologies. Although GVL or PPG as reported in the literature were used, the former resulted in a 17% decrease in product strength (580 vs 700 MPa) under the same process due to solvent-resin compatibility and debinding behavior matching issues; the latter, due to the severe degradation of slurry rheology and curing depth by PPG, could not yield intact products even with extremely slow debinding rates (as low as 1°C / min). These results clearly demonstrate that existing additive solutions cannot simply replace or be equivalent to the specific solvent design of this invention, and their effects fall far short of the synergistic effect achieved by this invention, which balances "printing stability," "rapid debinding," and "ultra-high strength" at high solids content.

[0099] Therefore, this invention is not a simple screening or optimization of existing additives, but rather a novel material solution based on the precise design of solvent physicochemical parameters, addressing the fundamental challenge of "active construction of exhaust channels" in high-performance ceramic photopolymer additive manufacturing. It has outstanding substantive features and significant progress.

[0100] Those skilled in the art will understand that the above embodiments are specific examples of implementing the present invention, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of the present invention. Any person skilled in the art can make their own modifications and alterations without departing from the spirit and scope of the present invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A photocurable ceramic slurry suitable for ultra-fast degreasing, characterized in that, Includes the following components by weight: Photosensitive resin monomer: 20-60 parts; the photosensitive resin monomer includes one or more of the following: polyurethane acrylate, aliphatic polyurethane acrylate, aromatic polyurethane acrylate, modified polyurethane acrylate, epoxy acrylate, polyester acrylate, pentaerythritol tetraacrylate ethoxylate, trimethylolpropane triacrylate, 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, isobornyl acrylate, and hydroxyethyl methacrylate. Photoinitiator: 0.5%~5% of the mass of the photosensitive resin monomer; Inert solvent: 10-50 parts; the inert solvent is selected from one or more of diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, tripropylene glycol methyl ether, and propylene glycol phenyl ether. Ceramic powder: 30-80 parts; Dispersant: 0.5%~5% of the mass of the ceramic powder; The inert solvent does not participate in the photocuring crosslinking reaction; the boiling point of the inert solvent is in the range of 180℃ to 250℃ and its relative volatility at 25℃ is less than 0.1 with reference to n-butyl acetate. The inert solvent is used to remove the photosensitive resin monomer by physical evaporation during the subsequent degreasing process through the thermal decomposition temperature range of the photosensitive resin monomer. The degreasing of the green body specifically includes: in air or an inert atmosphere, first heating to 150℃~250℃ at a rate of 1~5℃ / min and holding at that temperature for 0.2~2 hours. During this stage, the inert solvent evaporates preferentially and fully, forming a continuous initial pore network in the green body. The initial pore network is used to discharge the gas generated by the decomposition of the photosensitive resin in the subsequent stage, thereby avoiding gas pressure accumulation.

2. The photocurable ceramic slurry suitable for ultra-fast degreasing according to claim 1, characterized in that, The solid volume fraction of the slurry is 45%~60%, and it is applied in 30 seconds. -1 The viscosity at the shear rate is 1.5~15 Pa·s; and the solidification depth of the single layer formed by the curing of the slurry is not less than 30 μm.

3. The photocurable ceramic slurry suitable for ultra-fast degreasing according to claim 1, characterized in that, The ceramic powder is one or more of nitride ceramics, carbide ceramics, and boride ceramics.

4. The photocurable ceramic slurry suitable for ultra-fast degreasing according to claim 3, characterized in that, The ceramic powder is made from a single particle size powder or from two or more different particle sizes and then graded.

5. The photocurable ceramic slurry suitable for ultra-fast degreasing according to claim 3, characterized in that, The ceramic powder is a powder whose surface has been coated and modified to reduce the ultraviolet light absorption rate.

6. The photocurable ceramic slurry suitable for ultra-fast degreasing according to claim 1, characterized in that, The photoinitiator is a free radical photoinitiator, selected from one or more of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 2-isopropylthioxanthone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, and 1-hydroxycyclohexylphenyl ketone; The dispersant is a polymeric dispersant selected from one or more of BYK-111, BYK-108, BYK-180, BYK-190, KOS110, KOS163, KOS2400, TEGO Dispers 655, and Solsperse 41000.

7. A method for preparing a photocurable ceramic slurry suitable for ultra-fast degreasing according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1. The ceramic powder, dispersant, and all or part of the inert solvent are mixed and ball-milled to obtain a premix; S2. The premixed material is stirred and mixed with the photosensitive resin monomer, photoinitiator and remaining inert solvent under vacuum conditions and degassed to obtain the photocurable ceramic slurry suitable for ultra-fast degreasing.

8. The method for preparing a photocurable ceramic slurry suitable for ultra-fast degreasing according to claim 7, characterized in that, S1 specifically includes: ball milling for 1 to 6 hours; S2 specifically includes: stirring at 300~1500 rpm for 1~15 minutes, while simultaneously performing vacuum degassing.

9. The application of a photocurable ceramic slurry suitable for ultra-fast degreasing according to any one of claims 1 to 6 in the preparation of ceramic green bodies and ceramic products.

10. A ceramic green body, characterized in that, It is formed by photocuring 3D printing of a photocurable ceramic slurry suitable for ultra-fast degreasing as described in any one of claims 1 to 6.

11. A ceramic product, characterized in that, It is obtained by degreasing and sintering the ceramic green body as described in claim 10.

12. A method for preparing a ceramic article according to claim 11, characterized in that, The preparation method includes: subjecting the ceramic green body as described in claim 8 to the following degreasing treatment: under an air atmosphere or an inert atmosphere, first heating to 150℃~250℃ at a rate of 1~5℃ / min and holding at that temperature for 0.2~2 hours; then continuing to heat to 400℃~600℃.

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