Photocurable 3D printing ceramic core paste and preparation method thereof

Abstract

The application relates to a photocuring 3D printing ceramic core slurry and a preparation method, and relates to the technical field of photocuring 3D printing additive ceramic preparation. The preparation method of the photocuring 3D printing ceramic core slurry comprises the following steps: after ceramic base body powder and a mineralizer are mixed and treated, sintering treatment is carried out under a reducing atmosphere to obtain surface-modified solid-phase powder; wherein the sintering treatment temperature is 300-800 DEG C, and the sintering treatment time is 2-12 h; the surface-modified solid-phase powder, a photosensitive resin, a dispersing agent and a photoinitiator are prepared into the photocuring 3D printing ceramic core slurry. The application is mainly used for preparing a photocuring 3D printing ceramic core slurry with low viscosity, uniform stability and high solid content.

Description

Technical Field

[0001] This invention relates to the field of photopolymer 3D printing additive ceramic preparation technology, and in particular to a photopolymer 3D printing ceramic core slurry and its preparation method. Background Technology

[0002] With advancements in aviation technology, higher standards have been set for the temperature resistance of engine turbine blades. Currently, both domestic and international manufacturers are designing hollow turbine blades with complex cooling channels to improve the cooling efficiency of engine turbine inlets. Ceramic cores, as a key transitional component in the manufacture of hollow turbine blades, are becoming increasingly complex in structure.

[0003] Traditional ceramic cores are mainly obtained using hot injection molding technology, which is suitable for the mass production of simple ceramic cores. However, due to the limitations of molds, it cannot meet the production requirements of ceramic cores with hollow cooling channels. Therefore, there is an urgent need to find a new rapid prototyping process for complex ceramic cores.

[0004] Stereolithography 3D printing for ceramic cores is not limited by molds, offering low cost, high precision, and short processing cycles, providing a new fabrication technology for complex ceramic core structures. Currently, ceramic cores with complex internal cavity structures have been successfully fabricated using stereolithography 3D printing technology. However, due to the layered structure of 3D printing, the ceramic core blank is prone to shrinkage, deformation, and cracking after debinding and sintering, limiting its wider application.

[0005] The key to fabricating high-performance ceramic parts using photopolymer 3D printing lies in the preparation of the ceramic slurry. Experiments show that higher solid content in the ceramic slurry results in lower shrinkage rates during debinding and sintering, and fewer defects such as deformation and cracking. Therefore, increasing the solid content of the slurry while maintaining printability is a crucial area that urgently needs to be addressed in photopolymer 3D printing of ceramic cores. However, at least one technical challenge in preparing high-solid-content ceramic slurries is the poor wettability of hydrophilic ceramic particles with oily resins, making it difficult to disperse the ceramic particles in the resin. Summary of the Invention

[0006] In view of this, the present invention provides a photocurable 3D printing ceramic core slurry and its preparation method, the main purpose of which is to solve the problem of the difficulty in dispersing ceramic particles in photosensitive resin, so as to prepare a photocurable 3D printing ceramic core slurry with high solid content.

[0007] To achieve the above objectives, the present invention mainly provides the following technical solutions:

[0008] On one hand, embodiments of the present invention provide a method for preparing a photocurable 3D printing ceramic core slurry, which includes the following steps:

[0009] Preparation of surface-modified solid powder: ceramic matrix powder and mineralizer are mixed and treated, and then sintered in a reducing atmosphere to obtain surface-modified solid powder; wherein, the sintering temperature is 300-800℃ and the sintering time is 2-12h.

[0010] Preparation of ceramic core slurry: The surface-modified solid powder, photosensitive resin, dispersant, and photoinitiator are formulated into a photocurable 3D printing ceramic core slurry; wherein, at least two of the dispersant are selected from BYK9076, KOS110, BYK111, KOS163, and BYK180.

[0011] Preferably, the raw materials for preparing the photocurable 3D printing ceramic core slurry include, by weight: 65-75 parts by weight of ceramic matrix powder, 10-20 parts by weight of mineralizer, 1-3 parts by weight of photoinitiator, 10-20 parts by weight of photosensitive resin, and 3-8 parts by weight of dispersant.

[0012] Preferably, the ceramic matrix powder is selected from one or more of SiO2 and Al2O3; and / or the particle size of the ceramic matrix powder is 5-11 μm. And / or the mineralizer is selected from one or more of SiO2, Al2O3, ZrO2, and Y2O3; and / or the particle size of the mineralizer is 3-7 μm; and / or the particle size of the ceramic matrix powder is larger than the particle size of the mineralizer.

[0013] Preferably, in the step of preparing the surface-modified solid powder: when mixing the ceramic matrix powder and the mineralizer, the ceramic matrix powder with a large particle size is added first, and then the mineralizer with a small particle size is added.

[0014] Preferably, in the step of preparing the surface-modified solid powder: the surface of the particles of the surface-modified solid powder is coated with a layered film.

[0015] Preferably, in the step of preparing the surface-modified solid powder: the reducing atmosphere includes one or more gases selected from hydrogen, carbon monoxide, and hydrogen chloride.

[0016] Preferably, the photosensitive resin is one or more of ethylene glycol diacrylate, trimethylolpropane triacrylate, hydroxy methacrylate, tripropylene glycol diacrylate, and vinyl acetate.

[0017] Regarding the dispersant being two of BYK9076, KOS110, BYK111, KOS163, and BYK180, it should be noted that: (1) different dispersants act on different functional groups on the surface of ceramic powder; (2) different types of dispersants have different mechanisms of action, namely steric hindrance type and electrostatic repulsion type. Here, two different types of dispersants are selected to act on different sites on the ceramic surface to achieve synergistic dispersion. Preferably, the dispersant is BYK9076 and BYK111.

[0018] The photoinitiator is one or both of photoinitiator 851 (i.e., diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, also known as TPO) and photoinitiator 819 (i.e., bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, also known as BAPO); and / or the viscosity of the photosensitive resin is 40-80 MPa·s; and / or the viscosity of the dispersant is 40-80 MPa·s.

[0019] Preferably, the step of preparing the ceramic core slurry includes:

[0020] Preparation of liquid solvent: The photosensitive resin and dispersant are mixed to obtain a liquid solvent;

[0021] Preparation of slurry premix: The surface-modified solid powder and liquid solvent are mixed to obtain the slurry premix;

[0022] Preparation of ceramic core slurry: After adding a photoinitiator to the slurry premix, ball milling is performed to obtain photocurable 3D printing ceramic core slurry.

[0023] Preferably, in the step of preparing the ceramic core slurry, a photoinitiator and grinding beads are added to the slurry premix, and the slurry is ball-milled using a planetary ball mill; preferably, the planetary ball mill speed is 300-500 rpm / min, the ball milling time is 2-4 h, and the mass of the equal-diameter grinding beads is 1 / 3-2 / 3 of the sum of the mass of the slurry premix and the photoinitiator.

[0024] Preferably, the photocurable 3D printing ceramic core slurry comprises 65-75% solid phase and 25-35% liquid phase (the liquid phase here includes: photosensitive resin, dispersant, and photoinitiator) by volume fraction.

[0025] Furthermore, embodiments of the present invention provide a photocurable 3D printing ceramic core slurry, wherein the photocurable 3D printing ceramic core slurry is prepared by the preparation method of any one of the above-described photocurable 3D printing ceramic core slurries. Preferably, the solid content of the photocurable 3D printing ceramic core slurry is 65-75 vol% by volume fraction. Preferably, the solid content is [not specified] in 25-35 seconds.-1 At a shear rate of 7500-10000 mPa·s, the viscosity of the photocurable 3D printing ceramic core slurry is 7500-10000 mPa·s.

[0026] In another aspect, embodiments of the present invention provide a method for preparing a photopolymerizable 3D printed silicon-based ceramic core, wherein the preparation method includes the following steps:

[0027] The above-mentioned photopolymer 3D printing slurry was printed into a ceramic core blank using a photopolymer 3D printing process.

[0028] The ceramic core blank is degreased and sintered to obtain a photopolymer 3D printed ceramic core.

[0029] Compared with the prior art, the photopolymerizable 3D printing ceramic core slurry and its preparation method of the present invention have at least the following beneficial effects:

[0030] On one hand, embodiments of the present invention provide a method for preparing a photocurable 3D printing ceramic core slurry, comprising the following steps: mixing ceramic matrix powder and a mineralizer, and then sintering the mixture under a reducing atmosphere to obtain a surface-modified solid powder; wherein the sintering temperature is 300-800℃ and the sintering time is 2-12h; and the surface-modified solid powder, photosensitive resin, dispersant, and initiator are formulated into a photocurable 3D printing ceramic core slurry. It should be noted that the present invention, by sintering ceramic particles under a reducing atmosphere, reduces or removes cations on the surface of the ceramic particles, or converts them into hydroxyl bonds, thereby regulating the surface state of the ceramic particles. This alleviates the problem of incompatibility between the oxide ceramic particles and the oil-based photosensitive resin due to the hydrophilicity of the hydroxyl groups on the surface, improves the dispersibility of the ceramic particles in the slurry, thereby reducing the viscosity of the slurry and increasing its solid content. Simultaneously, at least two dispersants are selected for joint dispersion. On the one hand, different mechanisms of action determine that different types of dispersants have cross-effects in the slurry but also exhibit different dispersion effects. On the other hand, by utilizing the synergistic effect of at least two dispersants and the multi-site modification of ceramic particle surface (i.e., by utilizing the hydrophilic groups on the surface of the regularized ceramic particles, the incompatibility between hydrophilic oxide ceramic particles and oily photosensitive resin is improved, the dispersion of ceramic particles in liquid-phase photosensitive resin is increased, and the preparation of high solid content ceramic slurry is achieved), the ceramic particles are uniformly dispersed in the photosensitive resin, and the preparation of low viscosity, uniform and stable, high solid content photocurable 3D printing silicon-based ceramic core slurry is achieved.

[0031] Additionally, it should be noted that: (1) The surface of the solid powder modified by sintering is coated with a layered film. The uniform and continuous coating layer changes the surface morphology of the ceramic particles, making the particle surface smooth and stable, and improving the dispersion of the ceramic particles. The bonding between the thin films on the surface of the ceramic particles is better than the bonding between the ceramic particles, which enhances the adhesion between the ceramic particles. The layered structure of the core blank prepared by the modified powder is weakened, which enhances the physical properties of the ceramic core blank. (2) Modification by sintering can achieve uniform modification of large batches of powder. The difference between different batches of powder modified by this method is small, and the error is small.

[0032] Furthermore, the present invention provides a method for preparing a photopolymerizable 3D printing ceramic core slurry by selecting different powder particle sizes and adding them in different orders. During mixing, ceramic aggregate powder with larger particle size is added first, followed by mineralizer filler particles with smaller particle size. This reduces the agglomeration of mineralizer particles and allows them to be fully dispersed in the middle of the large particle skeleton, making the powder in the slurry more compact and achieving the preparation of a ceramic slurry with high solid content.

[0033] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0034] Figure 1 This is a flowchart illustrating a method for preparing a photopolymerizable 3D printing ceramic core slurry according to an embodiment of the present invention.

[0035] Figure 2 This is a schematic diagram illustrating the flowability of ceramic core slurry prepared according to embodiments and comparative examples of the present invention;

[0036] Figure 3 These are TEM images of solid-phase powders; among them, Figure 3 Figure (a) in the figure is a TEM image of the surface after modification in Example 1; Figure 3 Figure (b) in the figure is a TEM image of the solid powder in Example 1;

[0037] Figure 4 The image shows a white light interference pattern of a ceramic core blank prepared from the 3D printing ceramic core slurry of Example 1.

[0038] Figure 5 The image shows a white light interference pattern of the ceramic core blank prepared from the 3D printing ceramic core slurry of Comparative Example 1. Detailed Implementation

[0039] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the specific embodiments, structures, features, and effects according to the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "embodiments" or "embodiments" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0040] This invention mainly addresses the incompatibility between water-based oxide ceramic particles and oil-based photosensitive resin by modifying the surface of ceramic powder and adding dispersants, thereby promoting the dispersion of ceramic particles in the resin system and increasing the solid content of the slurry.

[0041] The main solutions of this invention are as follows:

[0042] On one hand, embodiments of the present invention provide a method for preparing photopolymerizable 3D printing ceramic core slurry, such as... Figure 1 As shown, it includes the following steps:

[0043] Preparation of surface-modified solid powder: ceramic matrix powder and mineralizer are mixed and treated, and then sintered in a reducing atmosphere to obtain surface-modified solid powder; wherein, the sintering temperature is 300-800℃ and the sintering time is 2-12h.

[0044] In this step: the ceramic matrix powder is selected from one or more of SiO2 and Al2O3; the mineralizing agent is selected from one or more of SiO2, Al2O3, ZrO2, and Y2O3.

[0045] The ceramic matrix powder is spherical in shape; the mineralizer powder is also spherical in shape.

[0046] In addition, the particle size of the ceramic matrix powder is 5-11 μm, and the particle size of the mineralizer powder is 3-7 μm.

[0047] In addition, when mixing ceramic matrix powder and mineralizer, the ceramic matrix powder with a larger particle size (skeleton) is added first, followed by the mineralizer with a slightly smaller particle size (filler powder).

[0048] In addition, reducing atmospheres include one or more gases selected from hydrogen, carbon monoxide, and hydrogen chloride.

[0049] Regarding the sintering process in this step, the following explanation is provided: The sintering process mainly involves surface modification of the ceramic particles, which reduces and removes the cations on the surface of the ceramic particles or transforms them into hydroxyl bonds. This regulates the surface state of the ceramic particles, alleviates the problem of incompatibility between the oxide ceramic particles and the oil-based photosensitive resin due to the hydrophilicity of the hydroxyl groups on the surface, improves the dispersibility of the ceramic particles in the slurry, reduces the viscosity of the slurry, and increases the solid content of the slurry.

[0050] Preparation of liquid solvent: The photosensitive resin and dispersant are mixed to obtain the liquid solvent.

[0051] In this step, the photosensitive resin and dispersant are mixed evenly to obtain a liquid solvent.

[0052] The photosensitive resin is one or more of ethylene glycol diacrylate, trimethylolpropane triacrylate, hydroxy methacrylate, tripropylene glycol diacrylate, and vinyl acetate. The dispersant is at least two of BYK9076, KOS110, BYK111, KOS163, and BYK180.

[0053] The viscosity of the photosensitive resin is 40-80 MPa·s. The viscosity of the dispersant is 40-80 MPa·s.

[0054] Preparation of slurry premix: The surface-modified solid powder and liquid solvent are mixed to obtain the slurry premix.

[0055] In this step, the surface-modified solid powder is added to the liquid solvent in batches, and a slurry premix is ​​prepared by mechanical stirring.

[0056] Preparation of ceramic core slurry: After adding a photoinitiator to the slurry premix, ball milling is performed to obtain photocurable 3D printing ceramic core slurry.

[0057] In this step, a photoinitiator and equal-diameter grinding balls are added to the slurry premix, and the mixture is ball-milled using a planetary ball mill to obtain a photocurable 3D printing ceramic core slurry. The planetary ball mill operates at a speed of 300-500 rpm / min, the milling time is 2-4 hours, and the mass of the equal-diameter grinding balls is 1 / 3-2 / 3 of the sum of the masses of the slurry premix and the photoinitiator.

[0058] The photoinitiator is one or both of photoinitiator 851 and photoinitiator 819.

[0059] Regarding the above steps: by weight, the raw materials for preparing the photocurable 3D printing ceramic core slurry include: 65-75 parts by weight of ceramic matrix powder, 10-20 parts by weight of mineralizer, 1-3 parts by weight of photoinitiator, 10-20 parts by weight of photosensitive resin, and 3-8 parts by weight of dispersant.

[0060] The photopolymer 3D printing ceramic core slurry comprises 65-75% solid phase and 25-35% liquid phase by volume fraction.

[0061] Regarding the above steps, it should be noted that:

[0062] On one hand, the present invention provides a method for preparing a photocurable 3D printing ceramic core slurry, which for the first time proposes to sinter ceramic particles in a reducing atmosphere to modify their surface. This process regulates the surface state of the ceramic particles, alleviates the problem of incompatibility between oxide ceramic particles and oil-based photosensitive resins due to the hydrophilicity of hydroxyl groups on the surface, improves the dispersibility of ceramic particles in the slurry, reduces the viscosity of the slurry, and increases the solid content of the slurry.

[0063] Furthermore, the method for preparing a photopolymerizable 3D printing ceramic core slurry provided in this embodiment of the invention uses at least two dispersants (such as BYK9076 + BYK111) for joint dispersion. Different mechanisms of action determine that different types of dispersants have overlapping effects in the slurry, yet exhibit different dispersion effects. This invention uses dual dispersants acting on the surface of ceramic particles at multiple sites, increasing the repulsive force between ceramic particles in the slurry, reducing the viscosity of the slurry, and thus increasing the solid content of the ceramic slurry.

[0064] Furthermore, the present invention provides a method for preparing a photocurable 3D printing ceramic core slurry by selecting different powder particle sizes and adding them in different order. During mixing, the ceramic matrix powder with a larger particle size is added first, followed by the mineralizer with a smaller particle size. This reduces the agglomeration of the mineralizer and allows it to be fully dispersed in the middle of the large particle skeleton, making the powder in the slurry more compact and achieving the preparation of a ceramic slurry with high solid content.

[0065] The present invention will be further illustrated below with specific embodiments:

[0066] Example 1

[0067] This embodiment provides a method for preparing a photocurable 3D printing ceramic core slurry. The raw materials used in the method and their weight proportions are as follows: 70 parts by weight of ceramic matrix powder, 10 parts by weight of mineralizer, 1 part by weight of photoinitiator, 16 parts by weight of photosensitive resin, and 3 parts by weight of dispersant. The ceramic matrix powder is SiO2 with a particle size of 5 μm; the mineralizer is a mixed powder of Al2O3 and ZrO2 with a particle size of 3 μm; the mass ratio of Al2O3 to ZrO2 is 20:4. The photosensitive resin is obtained by mixing ethylene glycol diacrylate and trimethylolpropane triacrylate at a volume ratio of 7:1. The dispersant is a mixture of BYK111 and BYK9076 at a volume ratio of 1:1. The photoinitiator is photoinitiator 851.

[0068] The preparation method of this embodiment mainly includes the following steps:

[0069] 1) After uniformly mixing the ceramic matrix powder and the mineralizer, a solid powder is obtained. The solid powder is sintered in a sintering furnace under a hydrogen atmosphere to obtain a surface-modified solid powder. The sintering temperature is 300℃ and the sintering time is 6 hours.

[0070] 2) Mix the photosensitive resin and dispersant evenly to obtain a liquid solvent.

[0071] 3) The surface-modified solid powder is added to the liquid solvent in batches and the slurry premix is ​​prepared by mechanical stirring at 400 rpm / min.

[0072] 4) Add photoinitiator and equal-diameter grinding balls to the slurry premix (wherein, the mass of the equal-diameter grinding balls is 2 / 3 of the sum of the mass of the slurry premix and the initiator), and ball mill for 2 hours at 400 rpm / min using a planetary ball mill to obtain a high-solids-content photocurable 3D printing ceramic core slurry.

[0073] Example 2

[0074] This embodiment provides a method for preparing a photocurable 3D printing ceramic core slurry. The raw materials used in the method and their weight proportions are as follows: 65 parts by weight of ceramic matrix powder, 15 parts by weight of mineralizer, 1 part by weight of photoinitiator, 16 parts by weight of photosensitive resin, and 3 parts by weight of dispersant. The ceramic matrix powder is SiO2 with a particle size of 5 μm; the mineralizer is a mixed powder of Al2O3 and ZrO2 with a particle size of 3 μm; the mass ratio of Al2O3 to ZrO2 is 20:4. The photosensitive resin is obtained by mixing ethylene glycol diacrylate and trimethylolpropane triacrylate at a volume ratio of 7:1. The dispersant is a mixture of BYK111 and BYK9076 at a volume ratio of 2:3. The photoinitiator is photoinitiator 851.

[0075] The preparation method of this embodiment mainly includes the following steps:

[0076] 1) After uniformly mixing the ceramic matrix powder and the mineralizer, a solid powder is obtained. The solid powder is sintered in a sintering furnace under a hydrogen atmosphere to obtain a surface-modified solid powder. The sintering temperature is 300℃ and the sintering time is 6 hours.

[0077] 2) Mix the photosensitive resin and dispersant evenly to obtain a liquid solvent.

[0078] 3) The surface-modified solid powder is added to the liquid solvent in batches and the slurry premix is ​​prepared by mechanical stirring at 400 rpm / min.

[0079] 4) Add photoinitiator and equal-diameter grinding balls to the slurry premix (wherein, the mass of the equal-diameter grinding balls is 2 / 3 of the sum of the mass of the slurry premix and the initiator), and ball mill for 2 hours at 400 rpm / min using a planetary ball mill to obtain a high-solids-content photocurable 3D printing ceramic core slurry.

[0080] Comparative Example 1

[0081] Comparative Example 1 provides a method for preparing a photocurable 3D printing ceramic core slurry. The raw materials used and their weight proportions are as follows: 70 parts by weight of ceramic matrix powder, 10 parts by weight of mineralizer, 1 part by weight of photoinitiator, 16 parts by weight of photosensitive resin, and 3 parts by weight of dispersant. The ceramic matrix powder is SiO2 with a particle size of 5 μm; the mineralizer is a mixed powder of Al2O3 and ZrO2 with a particle size of 3 μm; the mass ratio of Al2O3 to ZrO2 is 20:4. The photosensitive resin is obtained by mixing ethylene glycol diacrylate and trimethylolpropane triacrylate at a volume ratio of 7:1. The dispersant is a mixture of BYK111 and BYK9076 at a volume ratio of 1:1. The photoinitiator is photoinitiator 851.

[0082] The main steps are as follows:

[0083] 1) After the ceramic matrix powder and mineralizer are mixed evenly, a solid powder is obtained.

[0084] 2) After the photosensitive resin and dispersant are mixed evenly, a liquid solvent is obtained.

[0085] 3) The solid powder is added to the liquid solvent in batches and the mixture is mechanically stirred at 400 rpm / min to obtain a slurry premix.

[0086] 4) Add photoinitiator and equal-diameter grinding balls to the slurry premix (wherein, the mass of the equal-diameter grinding balls is 2 / 3 of the sum of the mass of the slurry premix and the initiator), and use a planetary ball mill to ball mill at 400 rpm / min for 2 hours to obtain a high solids content stereolithography 3D printing ceramic core slurry.

[0087] Comparative Example 2

[0088] Comparative Example 2 provides a method for preparing a photocurable 3D printing ceramic core slurry. The raw materials used in this method, in parts by weight, are: 70 parts by weight of ceramic matrix powder, 10 parts by weight of mineralizer, 1 part by weight of photoinitiator, 16 parts by weight of photosensitive resin, and 3 parts by weight of dispersant. The ceramic matrix powder is SiO2 with a particle size of 5 μm; the mineralizer is a mixed powder of Al2O3 and ZrO2 with a particle size of 3 μm; the mass ratio of Al2O3 to ZrO2 is 20:4. The photosensitive resin is obtained by mixing ethylene glycol diacrylate and trimethylolpropane triacrylate in a volume ratio of 7:1. The dispersant is BYK9076. The photoinitiator is photoinitiator 851.

[0089] The preparation method of this embodiment mainly includes the following steps:

[0090] 1) After uniformly mixing the ceramic matrix powder and the mineralizer, a solid powder is obtained. The solid powder is sintered in a sintering furnace under a hydrogen atmosphere to obtain a surface-modified solid powder. The sintering temperature is 300℃ and the sintering time is 6 hours.

[0091] 2) Mix the photosensitive resin and dispersant evenly to obtain a liquid solvent.

[0092] 3) The surface-modified solid powder is added to the liquid solvent in batches and the slurry premix is ​​prepared by mechanical stirring at 400 rpm / min.

[0093] 4) Add photoinitiator and equal-diameter grinding balls to the slurry premix (wherein, the mass of the equal-diameter grinding balls is 2 / 3 of the sum of the mass of the slurry premix and the initiator), and ball mill for 2 hours at 400 rpm / min using a planetary ball mill to obtain a high-solids-content photocurable 3D printing ceramic core slurry.

[0094] Comparative Example 3

[0095] Comparative Example 3 provides a method for preparing a photocurable 3D printing ceramic core slurry. The raw materials used and their weight proportions are as follows: 70 parts by weight of ceramic matrix powder, 10 parts by weight of mineralizer, 1 part by weight of photoinitiator, 16 parts by weight of photosensitive resin, and 3 parts by weight of dispersant. The ceramic matrix powder is SiO2 with a particle size of 5 μm; the mineralizer is a mixed powder of Al2O3 and ZrO2 with a particle size of 3 μm; the mass ratio of Al2O3 to ZrO2 is 20:4. The photosensitive resin is obtained by mixing ethylene glycol diacrylate and trimethylolpropane triacrylate at a volume ratio of 7:1. The dispersant is BYK9076. The photoinitiator is photoinitiator 851.

[0096] The main steps are as follows:

[0097] 1) After the ceramic matrix powder and mineralizer are mixed evenly, a solid powder is obtained.

[0098] 2) After the photosensitive resin and dispersant are mixed evenly, a liquid solvent is obtained.

[0099] 3) The solid powder is added to the liquid solvent in batches and the mixture is mechanically stirred at 400 rpm / min to obtain a slurry premix.

[0100] 4) Add photoinitiator and equal-diameter grinding balls to the slurry premix (wherein, the mass of the equal-diameter grinding balls is 2 / 3 of the sum of the mass of the slurry premix and the initiator), and use a planetary ball mill to ball mill at 400 rpm / min for 2 hours to obtain a high solids content stereolithography 3D printing ceramic core slurry.

[0101] Table 1

[0102] Testing items <![CDATA[Viscosity (30 s -1 )]]> Settlement rate Solid content Example 1 8470 mPa.s 0.066cm / h 70 vol.% Example 2 9050 mPa.s 0.069cm / h 70 vol.% Comparative Example 1 9810 mPa.s 0.084cm / h 70 vol.% Comparative Example 2 28750 mPa.s 0.127cm / h 70 vol.% Comparative Example 3 33420 mPa.s 0.147 m / h 70 vol.%

[0103] Figure 2 This is a schematic diagram illustrating the flowability of the ceramic core slurry prepared in the embodiments and comparative examples of the present invention. Table 1 shows the performance data of the ceramic core slurry prepared in the embodiments and comparative examples of the present invention. Figure 2 As can be clearly seen from Table 1, the embodiments of the present invention achieve the preparation of ceramic core slurry with high solid content, low viscosity, and uniform and stable properties through the synergistic effect of "surface-modified solid powder" + "dispersant".

[0104] Regarding the "synergistic effect," it's important to clarify that powder surface modification improves the surface morphology and chemical groups of ceramic particles, alleviating the incompatibility between hydrophilic oxide ceramic particles and oil-based photosensitive resins, thus increasing the dispersibility of ceramic particles in the liquid resin. Building upon this, the combination of dual dispersants increases the repulsive force between modified ceramic particles through electrostatic repulsion and steric hindrance mechanisms, further enhancing their dispersibility in the liquid resin. The combined effect of powder surface modification and the dual dispersant combination, through different mechanisms of action, achieves the goal of increasing the dispersibility of ceramic particles in the liquid resin.

[0105] Figure 3 These are TEM images of solid-phase powders; among them, Figure 3 Figure (a) in the figure is a TEM image of the surface-modified solid powder in Example 1; Figure 3 Figure (b) is a TEM image of the solid powder in Example 1. It can be seen that the surface-modified solid powder of Example 1 of the present invention forms regular ceramic particles. The surface of the modified ceramic powder is coated with a layered film. The uniform and continuous coating layer changes the surface morphology of the ceramic particles, making the surface of the particles smooth and stable, and improving the dispersion of the ceramic particles.

[0106] in addition, Figure 4 The image shows a white light interference pattern of a ceramic core blank prepared from the 3D printing ceramic core slurry of Example 1. Figure 5 This is a white light interferogram of the ceramic core blank prepared from the 3D printing ceramic core slurry of Comparative Example 1. From Figure 4 and Figure 5 It can be seen that the bonding between the thin films on the surface of the sintered modified ceramic particles is better than the bonding between the ceramic particles, which enhances the adhesion between the ceramic particles and weakens the layered structure of the core blank prepared from the modified powder. This phenomenon enhances the physical properties of the ceramic core blank.

[0107] In summary, the high solids content slurry prepared in the embodiments of the present invention was used to obtain a high solids content ceramic core through stereolithography 3D printing. After debinding and sintering, it was found that with the increase of solids content, the room temperature and high temperature (1500℃) flexural strength of the ceramic core were significantly improved, the sintering shrinkage in the three directions (X / Y / Z) was significantly reduced, the number of pores and voids in the microstructure of the core was reduced, and the structure was more compact.

[0108] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a photopolymerizable 3D printing ceramic core slurry, characterized in that, It includes the following steps: Preparation of surface-modified solid powder: ceramic matrix powder and mineralizer are mixed and treated, and then sintered in a reducing atmosphere to obtain surface-modified solid powder; wherein, the sintering temperature is 300-800℃ and the sintering time is 2-12h. Preparation of ceramic core slurry: The surface-modified solid powder, photosensitive resin, dispersant, and photoinitiator are formulated into a photocurable 3D printing ceramic core slurry; wherein, at least two of the dispersant are selected from BYK9076, KOS110, BYK111, KOS163, and BYK180; The ceramic matrix powder is selected from one or more of SiO2 and Al2O3.

2. The method for preparing the photopolymerizable 3D printing ceramic core slurry according to claim 1, characterized in that, The raw materials for preparing the photocurable 3D printing ceramic core slurry, by weight, include: 65-75 parts by weight of ceramic matrix powder, 10-20 parts by weight of mineralizer, 1-3 parts by weight of photoinitiator, 10-20 parts by weight of photosensitive resin, and 3-8 parts by weight of dispersant.

3. The method for preparing the photopolymerizable 3D printing ceramic core slurry according to claim 1, characterized in that, The ceramic matrix powder has a particle size of 5-11 μm; and / or The mineralizing agent is selected from one or more of SiO2, Al2O3, ZrO2, and Y2O3; and / or The mineralizer has a particle size of 3-7 μm; and / or The particle size of the ceramic matrix powder is larger than the particle size of the mineralizer.

4. The method for preparing the photopolymerizable 3D printing ceramic core slurry according to claim 1, characterized in that, In the step of preparing the surface-modified solid powder: When mixing ceramic matrix powder and mineralizer, first add the ceramic matrix powder with a large particle size, and then add the mineralizer with a small particle size.

5. The method for preparing the photopolymerizable 3D printing ceramic core slurry according to claim 1, characterized in that, In the step of preparing the surface-modified solid powder: The surface-modified solid powder particles are coated with a layered film; and / or The reducing atmosphere includes one or more gases selected from hydrogen, carbon monoxide, and hydrogen chloride.

6. The method for preparing the photopolymerizable 3D printing ceramic core slurry according to claim 1, characterized in that, The photosensitive resin is one or more of ethylene glycol diacrylate, trimethylolpropane triacrylate, hydroxy methacrylate, tripropylene glycol diacrylate, and vinyl acetate; and / or The dispersant is selected from BYK9076 and BYK111; and / or The photoinitiator is one or both of photoinitiator 851 and photoinitiator 819; and / or The viscosity of the photosensitive resin is 40-80 mPa·s; and / or The viscosity of the dispersant is 40-80 mPa·s.

7. The method for preparing photopolymerizable 3D printing ceramic core slurry according to claim 1, characterized in that, The step of preparing the ceramic core slurry includes: Preparation of liquid solvent: The photosensitive resin and dispersant are mixed to obtain a liquid solvent; Preparation of slurry premix: The surface-modified solid powder and liquid solvent are mixed to obtain the slurry premix; Preparation of ceramic core slurry: After adding a photoinitiator to the slurry premix, ball milling is performed to obtain photocurable 3D printing ceramic core slurry.

8. The method for preparing the photopolymerizable 3D printing ceramic core slurry according to claim 7, characterized in that, In the step of preparing ceramic core slurry, a photoinitiator and milling beads are added to the slurry premix, and the mixture is milled using a planetary ball mill.

9. The method for preparing the photopolymerizable 3D printing ceramic core slurry according to claim 8, characterized in that, The planetary ball mill operates at a speed of 300-500 rpm, with a milling time of 2-4 hours. The mass of the equal-diameter milling beads is 1 / 3 to 2 / 3 of the sum of the mass of the slurry premix and the photoinitiator.

10. The method for preparing the photopolymerizable 3D printing ceramic core slurry according to claim 1, characterized in that, By volume fraction, the photocurable 3D printing ceramic core slurry comprises 65-75% solid phase and 25-35% liquid phase.

11. A photopolymerizable 3D printing ceramic core slurry, characterized in that, The photocurable 3D printing ceramic core slurry is prepared by the method described in any one of claims 1-10.

12. The photopolymerizable 3D printing ceramic core slurry according to claim 11, characterized in that, The solid content of the photocurable 3D printing ceramic core slurry is 65-75 vol by volume fraction.

13. The photopolymerizable 3D printing ceramic core slurry according to claim 11, characterized in that, In 25-35s -1 At a shear rate of 7500-10000 mPa·s, the viscosity of the photocurable 3D printing ceramic core slurry is 7500-10000 mPa·s.

14. A method for preparing a photopolymerizable 3D printed silicon-based ceramic core, characterized in that, The preparation method includes the following steps: The photopolymer 3D printing slurry of any one of claims 11-13 is printed into a ceramic core blank using a photopolymer 3D printing process. The ceramic core blank is degreased and sintered to obtain a photopolymer 3D printed ceramic core.

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