3D printing ceramic slurry, preparation method and application thereof, and preparation method of silicon nitride ceramic

Abstract

The embodiment of the invention relates to the technical field of 3D printing, and provides 3D printing ceramic slurry, a preparation method and application thereof and a preparation method of silicon nitride ceramic, and the 3D printing ceramic slurry at least has high solid content and high strength performance under the condition of low viscosity. The 3D printing ceramic slurry comprises inorganic powder, photosensitive resin, a dispersing agent and a photoinitiator, the inorganic powder comprises silicon nitride coarse powder and silicon nitride fine powder, the average particle size of the silicon nitride coarse powder is 1-1.5 mu m, the average particle size of the silicon nitride fine powder is 0.1-0.7 mu m, and the mass ratio of the silicon nitride coarse powder to the silicon nitride fine powder is 1: 9-4: 6; the inorganic powder accounts for 30 vol%-50 vol% of the total solid content of the inorganic powder and the photosensitive resin; the mass ratio of the dispersing agent to the inorganic powder is 0.01-0.08; the mass ratio of the photoinitiator to the photosensitive resin is 0.015 to 0.05.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of 3D printing technology, and in particular to a 3D printing ceramic slurry, a preparation method and application thereof, and a preparation method of silicon nitride ceramics. Background Art

[0002] Silicon nitride ceramics have excellent comprehensive properties inherent in ceramic materials, such as high strength, high fracture toughness, high temperature resistance, oxidation resistance and small thermal expansion coefficient. They also have relatively low dielectric constant and dielectric loss. Silicon nitride ceramics play a vital role in many fields with its excellent comprehensive properties in all aspects, and have become one of the indispensable materials in the development of modern science and technology.

[0003] Due to the high strength and poor toughness of silicon nitride ceramic materials, it is very challenging to achieve the precise design and preparation of regular ceramic lattice structures through post-processing processes such as machining and cutting. Although new ceramic molding processes such as gel casting, slip casting, and injection molding can solve the problem of preparing ceramics with regularly distributed internal pores, it is still extremely difficult to manufacture high-precision structural ceramics with particularly complex shapes.

[0004] Combining 3D (Three Dimension Printing) printing technology with the preparation process of ceramics has made it possible to control the macroscopic physical properties of ceramic materials by changing their structural design. However, due to the high viscosity, poor flow and optical properties of silicon nitride ceramic materials themselves, they face many problems in the field of photocuring ceramic slurries. The solid phase content of silicon nitride ceramic slurries is difficult to increase, the dispersion is difficult, and the curing depth is low. These factors directly affect the molding of silicon nitride ceramic materials and the improvement of their properties. Summary of the invention

[0005] The embodiments of the present application provide a 3D printing ceramic slurry, a preparation method and application thereof, and a preparation method of silicon nitride ceramics, which can at least have both high solid content and high strength performance under low viscosity conditions.

[0006] According to some embodiments of the present application, on the one hand, the embodiments of the present application provide a 3D printing ceramic slurry, including: an inorganic powder, the inorganic powder including coarse silicon nitride powder and fine silicon nitride powder, the average particle size of the coarse silicon nitride powder is 1 μm to 1.5 μm, the average particle size of the fine silicon nitride powder is 0.1 μm to 0.7 μm, and the mass ratio of the coarse silicon nitride powder to the fine silicon nitride powder is 1:9 to 4:6; a photosensitive resin, the solid content of the inorganic powder in the total of the inorganic powder and the photosensitive resin is 30 vol% to 50 vol%; a dispersant, the mass ratio of the dispersant to the inorganic powder is 0.01 to 0.08; a photoinitiator, the mass ratio of the photoinitiator to the photosensitive resin is 0.015 to 0.05.

[0007] In some embodiments, the inorganic powder also includes: yttrium oxide and magnesium oxide. The mass fractions of the substances in the inorganic powder are: the total mass fraction of silicon nitride coarse powder and silicon nitride fine powder is 75 to 85 parts, the mass fraction of yttrium oxide is 5 to 15 parts, and the mass fraction of magnesium oxide is 5 to 15 parts.

[0008] In some embodiments, the total mass of yttrium oxide and magnesium oxide accounts for 5% to 20% of the total mass of the inorganic powder.

[0009] In some embodiments, the photosensitive resin is selected from: one or more of 2-hydroxyethyl acrylate, 1,6-hexanediol diacrylate or trimethylolpropane triacrylate; the dispersant is selected from: one or more of sodium tripolyphosphate, sodium hexametaphosphate or sodium pyrophosphate; the initiator is selected from: one or more of phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, bis(1-(2,4-difluorophenyl)-3-pyrrolyl)titanocene, 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone.

[0010] According to some embodiments of the present application, on the other hand, the embodiments of the present application also provide a method for preparing a 3D printing ceramic slurry, comprising: weighing silicon nitride coarse powder, silicon nitride fine powder, photosensitive resin, dispersant and photoinitiator according to the 3D printing ceramic slurry in the above-mentioned embodiments; mixing the silicon nitride coarse powder and the silicon nitride fine powder with an ethanol solution and performing a first ball milling treatment to obtain a premix, wherein the silicon nitride coarse powder and the silicon nitride fine powder together account for 30 vol% to 50 vol% of the total solid content of the silicon nitride coarse powder, the silicon nitride fine powder and the ethanol solution; drying and grinding the premix to obtain an inorganic mixed powder; mixing the inorganic mixed powder with a photosensitive resin to obtain a premixed liquid; adding a photoinitiator and a dispersant to the premixed liquid and performing a second ball milling treatment to obtain an initial slurry; filtering the initial slurry through a sieve to obtain a target slurry.

[0011] In some embodiments, the first ball milling treatment is performed at a rotation speed of 100 r / min to 200 r / min for 8 h to 10 h; the second ball milling treatment is performed at a rotation speed of 1000 r / min to 2000 r / min for 10 h to 12 h.

[0012] In some embodiments, the drying process is performed at a temperature of 80° C. to 100° C. and for a time of 10 h to 12 h.

[0013] In some embodiments, the mesh size of the sieve is 100-300 mesh.

[0014] In some embodiments, the grinding process lasts for 30 min to 40 min.

[0015] According to some embodiments of the present application, the embodiments of the present application further provide a method for preparing silicon nitride ceramics, comprising: using the 3D printing ceramic slurry in the above embodiment as a raw material or using the target slurry prepared by the preparation method of the 3D printing ceramic slurry in the above embodiment as a raw material, and printing layer by layer by a 3D printer to prepare a silicon nitride ceramic embryo, and the exposure intensity of the 3D printer printing is 60mW / cm 2 ~150mW / cm 2 , the exposure time of the bottom layer is 1s to 4s, the exposure time of the normal layer is 3s to 6s, the printed layer thickness is 30μm to 60μm, and the scraper speed is 600mm / min to 1800mm / min; vacuum debinding treatment is performed, and the silicon nitride ceramic body is heated to 300℃ to 500℃ in a vacuum furnace at a rate of 0.1℃ / min to 0.5℃ / min, and then kept warm for 1h to 3h; air decarbonization treatment is performed, and the silicon nitride ceramic body is heated to 500℃ to 700℃ in a muffle furnace at a rate of 5℃ / min to 15℃ / min, and then kept warm for 0.5h to 1.5h; sintering treatment is performed, and the silicon nitride ceramic body is heated to 1800℃ to 2000℃ at a rate of 1℃ / min to 10℃ / min, and then sintered for 1h to 3h.

[0016] According to some embodiments of the present application, on the other hand, the embodiments of the present application further provide an application of the 3D printing ceramic slurry in the above embodiments in 3D printing technology.

[0017] The technical solution provided by the embodiments of the present application has at least the following advantages:

[0018] The present application provides a 3D printing ceramic slurry, a preparation method and application thereof, and a preparation method of silicon nitride ceramics. The 3D printing ceramic slurry includes an inorganic powder, a photosensitive resin, a dispersant and a photoinitiator, wherein the inorganic powder includes coarse silicon nitride powder (with an average particle size of 1 μm to 1.5 μm) and fine silicon nitride powder (with an average particle size of 0.1 μm to 0.7 μm), and the mass ratio of the coarse silicon nitride powder to the fine silicon nitride powder is 1:9 to 4:6. By allocating the ratio of the coarse silicon nitride powder to the fine silicon nitride powder, and adjusting the amount of the photosensitive resin, dispersant and photoinitiator in the 3D printing ceramic slurry, a silicon nitride ceramic slurry with a high solid content and low viscosity is obtained, thereby solving the problems of poor photocuring performance of the 3D printing ceramic slurry and low strength of the photocured ceramic embryo, and the prepared silicon nitride ceramic has high density and mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise specified, the pictures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present application or the technical solutions in the traditional technology, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A flowchart corresponding to the method for preparing a 3D printing ceramic slurry provided in an embodiment of the present application;

[0021] Figure 2 This is a flow chart corresponding to the method for preparing silicon nitride ceramics provided in an embodiment of the present application. DETAILED DESCRIPTION

[0022] From the background technology, we can know that due to the high viscosity, poor flow and optical properties of silicon nitride ceramic materials themselves, they face many problems in the field of photocuring ceramic slurry. The solid phase content of silicon nitride ceramic slurry is difficult to increase, the dispersion is difficult, and the curing depth is low. These factors directly affect the molding of silicon nitride ceramic materials and the improvement of their properties.

[0023] In the related art, the solid content is increased by introducing dispersants or surface modification into silicon nitride ceramic slurry, thereby improving the strength of the silicon nitride ceramic body after molding. However, while these methods increase the solid content of the ceramic slurry and the strength of the ceramic body, they often lead to a decrease in the dispersion of the material, making the ceramic slurry difficult to prepare and unsuitable for photocuring processes, and it is difficult to meet the needs of photocuring production application scenarios. In addition, the stability issues of silicon nitride powder in ceramic slurries with high solid content, such as sedimentation and uneven curing, have not been fully resolved, resulting in large fluctuations in the quality of printed parts.

[0024] The present application provides a 3D printing ceramic slurry, a preparation method and application thereof, and a preparation method of silicon nitride ceramics. The 3D printing ceramic slurry includes an inorganic powder, a photosensitive resin, a dispersant and a photoinitiator, wherein the inorganic powder includes coarse silicon nitride powder (with an average particle size of 1 μm to 1.5 μm) and fine silicon nitride powder (with an average particle size of 0.1 μm to 0.7 μm), and the mass ratio of the coarse silicon nitride powder to the fine silicon nitride powder is 1:9 to 4:6. By allocating the ratio of the coarse silicon nitride powder to the fine silicon nitride powder, and adjusting the amount of the photosensitive resin, dispersant and photoinitiator in the 3D printing ceramic slurry, a silicon nitride ceramic slurry with a high solid content and low viscosity is obtained, thereby solving the problems of poor photocuring performance of the 3D printing ceramic slurry and low strength of the photocured ceramic embryo, and the prepared silicon nitride ceramic has high density and mechanical properties.

[0025] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0026] In the description of the embodiments of the present application, “plurality” means more than two, unless otherwise clearly and specifically defined.

[0027] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0028] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0029] In the description of the embodiments of the present application, when a certain component “includes” another component, unless otherwise stated, other components are not excluded and other components may be further included.

[0030] The terms used in the description of the various described embodiments herein are used only to describe specific embodiments and are not intended to be limiting. As used in the description of the various described embodiments and the appended claims, "components" are also intended to include plural forms unless the context clearly indicates otherwise.

[0031] The following will describe the various embodiments of the present application in detail with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that in the various embodiments of the present application, many technical details are provided in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solution claimed in the present application can be implemented.

[0032] According to some embodiments of the present application, on the one hand, the embodiments of the present application provide a 3D printing ceramic slurry, including: an inorganic powder, the inorganic powder including coarse silicon nitride powder and fine silicon nitride powder, the average particle size of the coarse silicon nitride powder is 1 μm to 1.5 μm, the average particle size of the fine silicon nitride powder is 0.1 μm to 0.7 μm, and the mass ratio of the coarse silicon nitride powder to the fine silicon nitride powder is 1:9 to 4:6; a photosensitive resin, the solid content of the inorganic powder in the total of the inorganic powder and the photosensitive resin is 30 vol% to 50 vol%; a dispersant, the mass ratio of the dispersant to the inorganic powder is 0.01 to 0.08; a photoinitiator, the mass ratio of the photoinitiator to the photosensitive resin is 0.015 to 0.05.

[0033] In a particle group composed of single silicon nitride particles of different sizes, the average particle size is expressed as the equivalent diameter of the largest particle when the cumulative distribution in the particle size distribution curve is 50%. For example, the average particle size of the coarse silicon nitride powder can be 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm or 1.5 μm, etc.; the average particle size of the fine silicon nitride powder can be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm or 0.7 μm, etc.

[0034] The mass ratio of the coarse silicon nitride powder to the fine silicon nitride powder can be 1:9, 2:8, 3:7 or 4:6.

[0035] The solid content of the inorganic powder in the total of the inorganic powder and the photosensitive resin can be specifically 30 vol%, 33 vol%, 38 vol%, 40 vol%, 42 vol%, 45 vol%, 47 vol% or 50 vol%, etc.

[0036] The mass ratio of the dispersant to the inorganic powder may specifically be 0.0.1, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07 or 0.08.

[0037] The mass ratio of the photoinitiator to the photosensitive resin may specifically be 0.015, 0.02, 0.026, 0.03, 0.034, 0.04, 0.045 or 0.05.

[0038] In some embodiments, the inorganic powder may further include: yttrium oxide and magnesium oxide, and the mass fractions of the substances in the inorganic powder are: the mass fractions of the total silicon nitride coarse powder and silicon nitride fine powder are 75 to 85 parts, the mass fractions of yttrium oxide are 5 to 15 parts, and the mass fractions of magnesium oxide are 5 to 15 parts. For example, the mass fractions of the total silicon nitride coarse powder and silicon nitride fine powder can be 75, 78, 80, 82 or 85 parts, etc.; the mass fractions of yttrium oxide can be 5, 6, 8, 10, 13 or 15 parts, etc.; the mass fractions of magnesium oxide can be 5, 6, 8, 10, 13 or 15 parts, etc. As sintering aids, yttrium oxide and magnesium oxide can help improve the sintering activity of ceramic ligands prepared by 3D printing ceramic slurry during sintering treatment. A high content of magnesium oxide helps densification, but due to the high vapor pressure of magnesium oxide at high temperatures, samples containing only magnesium oxide sintering aids cannot be fully densified; as the content of yttrium oxide increases, the degree of densification will also increase, but excessive yttrium oxide will also be harmful to densification, so coordinating the ratio of yttrium oxide and magnesium oxide can change the properties of silicon carbide ceramics.

[0039] In some embodiments, the total mass of yttrium oxide and magnesium oxide accounts for 5% to 20% of the total mass of the inorganic powder, and can be specifically 5%, 8%, 10%, 13%, 15%, 18% or 20%. The total mass of yttrium oxide and magnesium oxide needs to be within an appropriate range to avoid affecting the dispersibility of the inorganic powder in the photosensitive resin.

[0040] In some embodiments, the photosensitive resin is selected from: one or more of 2-hydroxyethyl acrylate, 1,6-hexanediol diacrylate or trimethylolpropane triacrylate; the dispersant is selected from: one or more of sodium tripolyphosphate, sodium hexametaphosphate or sodium pyrophosphate; the initiator is selected from: one or more of phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, bis(1-(2,4-difluorophenyl)-3-pyrrolyl)titanocene, 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone.

[0041] In some embodiments, the 3D printing ceramic slurry may further include a defoamer, and the mass of the defoamer accounts for 0.05% to 0.1% of the total mass of the 3D printing ceramic slurry, and specifically may be 0.05%, 0.06%, 0.07%, 0.08%, 0.09% or 0.1%.

[0042] The present application provides a 3D printing ceramic slurry including an inorganic powder, a photosensitive resin, a dispersant and a photoinitiator, wherein the inorganic powder includes coarse silicon nitride powder (with an average particle size of 1 μm to 1.5 μm) and fine silicon nitride powder (with an average particle size of 0.1 μm to 0.7 μm). The fine silicon nitride powder with a smaller average particle size improves the stability of the 3D printing ceramic slurry, and the fine silicon nitride powder has a smaller average particle size and lower gravity, and the significant influence of Brownian motion reduces the sedimentation ability of the fine silicon nitride powder; in addition, the addition of the fine silicon nitride powder increases the sedimentation resistance of the coarse silicon nitride powder, resulting in a significant reduction in the overall sedimentation rate of the 3D printing ceramic slurry. By allocating the ratio of coarse silicon nitride powder and fine silicon nitride powder, and adjusting the dosage of photosensitive resin, dispersant and photoinitiator in 3D printing ceramic slurry, a silicon nitride ceramic slurry with high solid content and low viscosity is obtained, thereby solving the problems of poor photocuring performance of 3D printing ceramic slurry and low strength of photocured ceramic embryos. The prepared silicon nitride ceramics have high density and mechanical properties.

[0043] Correspondingly, another embodiment of the present application also provides a method for preparing a 3D printing ceramic slurry, which can be used to manufacture the 3D printing ceramic slurry provided in the above embodiment. The following will describe in detail the method for preparing a 3D printing ceramic slurry provided in another embodiment of the present application in conjunction with the accompanying drawings. For the parts that are the same or corresponding to the previous embodiment, refer to the corresponding description of the previous embodiment, and will not be described in detail below.

[0044] Figure 1 Flow chart corresponding to the method for preparing 3D printing ceramic slurry provided in an embodiment of the present application.

[0045] refer to Figure 1 The method for preparing the 3D printing ceramic slurry provided in the embodiment of the present application includes:

[0046] Step 11: Weigh silicon nitride coarse powder, silicon nitride fine powder, photosensitive resin, dispersant and photoinitiator according to the 3D printing ceramic slurry in the above embodiment;

[0047] Step 12: mixing the silicon nitride coarse powder and the silicon nitride fine powder with the ethanol solution and then performing a first ball milling process to obtain a premix, wherein the silicon nitride coarse powder and the silicon nitride fine powder together account for 30 vol% to 50 vol% of the solid content of the silicon nitride coarse powder, the silicon nitride fine powder and the ethanol solution;

[0048] Step 13: drying and grinding the premix to obtain an inorganic mixed powder;

[0049] Step 14: Mixing the inorganic mixed powder with the photosensitive resin to obtain a premixed solution;

[0050] Step 15: adding a photoinitiator and a dispersant to the premixed liquid for a second ball milling process to obtain an initial slurry;

[0051] Step 16: Filter the initial slurry through a sieve to obtain the target slurry.

[0052] In step 12, the rotation speed of the first ball milling treatment is 100 r / min to 200 r / min, specifically 100 r / min, 130 r / min, 150 r / min, 180 r / min or 200 r / min, etc.; the time is 8 h to 10 h, specifically 8 h, 8.5 h, 9 h, 9.5 h or 10 h, etc. In step 15, the rotation speed of the second ball milling treatment is 1000 r / min to 2000 r / min, specifically 1000 r / min, 1200 r / min, 1500 r / min, 1800 r / min or 2000 r / min, etc.; the time is 10 h to 12 h, specifically 10 h, 10.6 h, 11 h, 11.4 h or 12 h, etc. The ball milling time and speed determine the uniformity of particle dispersion. If the high-energy ball milling time is too long, the ball milling temperature may be maintained at a high state, increasing the possibility of oxidation contamination of the ball milling materials, and also causing the ball milling materials to agglomerate, greatly affecting the performance of the material; if the ball milling speed reaches or exceeds the critical speed, the ball milling medium will move close to the inner wall of the tank and will not be thrown off, greatly weakening the collision and extrusion effect of the ball milling medium on the ball milling materials. Therefore, the ball milling time and ball milling speed need to be adjusted within an appropriate range.

[0053] In step 13, the drying temperature is 80°C to 100°C, specifically 80°C, 85°C, 90°C, 95°C or 100°C, etc.; the drying time is 10h to 12h, specifically 10h, 10.6h, 11h, 11.4h or 12h, etc. The drying temperature and time determine the degree of drying of the solvent, and the time and temperature need to be within an appropriate range to avoid residual solvent from affecting the performance of the slurry.

[0054] In step 13, the grinding time is 30 min to 40 min, specifically 30 min, 33 min, 35 min, 38 min or 40 min, etc. The grinding time needs to be within an appropriate range to avoid the problem of agglomeration of the inorganic mixed powder after drying.

[0055] In step 11, if yttrium oxide and magnesium oxide are also weighed according to the above embodiment, then in step 14, during the process of mixing the inorganic mixed powder with the photosensitive resin, yttrium oxide and magnesium oxide are also added to the photosensitive resin.

[0056] In step 16, the mesh number of the sieve can be 100-300 meshes, specifically 100 meshes, 120 meshes, 150 meshes, 180 meshes, 200 meshes, 230 meshes, 260 meshes, 290 meshes or 300 meshes, etc. When the mesh number of the sieve is within a suitable range, the waste of the slurry can be reduced while the final target slurry meets the required uniformity.

[0057] In the preparation method of 3D printing ceramic slurry provided in the embodiment of the present application, silicon nitride coarse powder and silicon nitride fine powder are first mixed with an ethanol solution to obtain a premix, and the premix is ​​subjected to a first ball milling treatment to uniformly disperse the silicon nitride coarse powder and the silicon nitride fine powder first, and the two silicon nitride powders with different average particle sizes are mixed by a wet mixing process, so as to effectively improve the packing density of the powder in the 3D printing ceramic slurry, and the mutual adsorption force of powders with different particle sizes is optimized, and the powder dispersion of the 3D printing ceramic slurry is not easy to agglomerate, which is conducive to improving The quality of the printed part is improved; the premix is ​​then dried to remove the ethanol solution, and the silicon nitride coarse powder is prevented from agglomerating into lumps by grinding; a photoinitiator and a dispersant are added to the premix to obtain a premix of the inorganic mixed powder and the photosensitive resin, and a second ball milling treatment is performed to uniformly disperse the silicon nitride coarse powder, the silicon nitride fine powder, the dispersant and the photoinitiator in the photosensitive resin; and a target slurry that is uniformly dispersed and free of impurities is obtained by filtering through a sieve, and the target slurry has excellent dispersion performance and a high solid content.

[0058] Correspondingly, the present application also provides a method for preparing silicon nitride ceramics on the other hand, using the 3D printing ceramic slurry in the above embodiment as a raw material or the target slurry prepared by the preparation method of the 3D printing ceramic slurry in the above embodiment as a raw material. The preparation method of silicon nitride ceramics provided in the embodiment of the present application will be described in detail below in conjunction with the accompanying drawings. For the parts that are the same or corresponding to the above embodiments, refer to the corresponding description of the above embodiments, and will not be described in detail below.

[0059] Figure 2 This is a flow chart corresponding to the method for preparing silicon nitride ceramics provided in an embodiment of the present application.

[0060] refer to Figure 2 The method for preparing silicon nitride ceramics provided in the embodiment of the present application includes:

[0061] Step 21: Using the 3D printing ceramic slurry in the above embodiment as a raw material or the target slurry prepared by the preparation method of the 3D printing ceramic slurry in the above embodiment as a raw material, a silicon nitride ceramic body is prepared by printing layer by layer through a 3D printer. The exposure intensity of the 3D printer printing is 60mW / cm 2 ~150mW / cm 2, the exposure time of the bottom layer is 1s~4s, the exposure time of the normal layer is 3s~6s, the printed layer thickness is 30μm~60μm, and the scraper speed is 600mm / min~1800mm / min;

[0062] Step 22: performing vacuum debinding treatment, heating the silicon nitride ceramic body in a vacuum furnace at a rate of 0.1°C / min to 0.5°C / min to 300°C to 500°C and then keeping the temperature for 1h to 3h;

[0063] Step 23: performing air decarbonization treatment, heating the silicon nitride ceramic body in a muffle furnace at a rate of 5°C / min to 15°C / min to 500°C to 700°C, and then keeping the temperature for 0.5h to 1.5h;

[0064] Step 24: Perform sintering treatment, raise the temperature of the silicon nitride ceramic body to 1800° C. to 2000° C. at a rate of 1° C. / min to 10° C. / min, and then sinter for 1 h to 3 h.

[0065] In step 21, when the 3D printing ceramic slurry in the above embodiment is used as the raw material, the components can be directly mixed in a ball mill. The ball mill stirring rate can be 200r / min to 250r / min, and the time can be 8h to 12h.

[0066] In step 21, the exposure intensity of the 3D printer printing can be specifically 60mW / cm 2 、82mW / cm 2 、96mW / cm 2 、104mW / cm 2 、115mW / cm 2 、130mW / cm 2 、136mW / cm 2 or 150mW / cm 2 etc.; the exposure time of the bottom layer can be specifically 1s, 2s, 3s or 4s; the exposure time of the normal layer can be specifically 3s, 4s, 5s or 6s; the printed layer thickness can be specifically 30μm, 33μm, 35μm, 37μm, 40μm, 44μm, 46μm, 48μm, 50μm, 55μm or 60μm; the speed of the scraper can be specifically 600mm / min, 700mm / min, 880mm / min, 950mm / min, 1000mm / min, 1200mm / min, 1550mm / min, 1700mm / min or 1800mm / min, etc.

[0067] In step 22, the heating rate can be specifically 0.1℃ / min, 0.2℃ / min, 0.3℃ / min, 0.4℃ / min or 0.5℃ / min; the termination temperature of the heating can be specifically 300℃, 330℃, 350℃, 370℃, 400℃, 420℃, 450℃, 480℃ or 500℃; the insulation time can be specifically 1h, 1.4h, 1.6h, 2h, 2.2h, 2.5h, 2.8h or 3h.

[0068] In step 23, the heating rate can be specifically 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min, 11℃ / min, 12℃ / min, 13℃ / min, 14℃ / min or 15℃ / min; the termination temperature of the heating can be specifically 500℃, 530℃, 550℃, 570℃, 600℃, 620℃, 650℃, 680℃ or 700℃; the insulation time can be specifically 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.2h or 1.5h.

[0069] In step 24, the heating rate can be specifically 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min or 10°C / min; the sintering temperature can be specifically 1800°C, 1850°C, 1870°C, 1900°C, 1920°C, 1950°C, 1980°C or 2000°C; the sintering time can be specifically 1h, 1.4h, 1.6h, 2h, 2.2h, 2.5h, 2.8h or 3h.

[0070] According to some embodiments of the present application, on the other hand, the embodiments of the present application further provide an application of the 3D printing ceramic slurry in the above embodiment in 3D printing technology, using the 3D printing ceramic slurry in the above embodiment as a raw material or the target slurry prepared by the preparation method of the 3D printing ceramic slurry in the above embodiment as a raw material, combining 3D printing technology with the ceramic preparation process to prepare ceramic materials.

[0071] The following are specific embodiments of the present application:

[0072] Embodiment 1:

[0073] Weigh silicon nitride coarse powder, silicon nitride fine powder, yttrium oxide, magnesium oxide, photosensitive resin, dispersant and photoinitiator, wherein the average particle size of silicon nitride coarse powder is 1.5 μm, the average particle size of silicon nitride fine powder is 0.7 μm, and the mass ratio of silicon nitride coarse powder to silicon nitride fine powder is 1:9; the total solid content of silicon nitride coarse powder and silicon nitride fine powder to the total solid content of silicon nitride coarse powder, silicon nitride fine powder and photosensitive resin is 45 vol%; the mass ratio of silicon nitride coarse powder and silicon nitride fine powder to the total solid content of yttrium oxide and magnesium oxide is 80:10:10; the mass ratio of dispersant to silicon nitride coarse powder, silicon nitride fine powder, yttrium oxide and magnesium oxide is 0.02; the mass ratio of photoinitiator to photosensitive resin is 0.04;

[0074] The silicon nitride coarse powder and the silicon nitride fine powder are mixed with the ethanol solution and then subjected to a first ball milling treatment to obtain a premix, wherein the silicon nitride coarse powder and the silicon nitride fine powder account for 45 vol% of the total solid content of the silicon nitride coarse powder, the silicon nitride fine powder and the ethanol solution; the first ball milling treatment is performed at a rotation speed of 150 r / min and a time of 8 hours;

[0075] The premix is ​​dried and milled to obtain an inorganic mixed powder, the drying temperature is 90°C, the time is 12 hours, and the milling time is 30 minutes;

[0076] Mixing the inorganic mixed powder, yttrium oxide and magnesium oxide with a photosensitive resin to obtain a premixed solution;

[0077] Adding the photoinitiator and the dispersant into the premixed liquid for a second ball milling process to obtain an initial slurry; the second ball milling process has a rotation speed of 1500 r / min and a time of 12 h;

[0078] The target slurry is obtained by filtering the initial slurry through a sieve having a mesh size of 200 meshes;

[0079] Pour the target slurry into the 3D printer’s material tank, set the wavelength to 382nm, and the exposure intensity to 120mW / cm 2 , the exposure time of the bottom layer is 3s, the exposure time of the normal layer is 4s, the printing layer thickness is 50μm, the scraper speed is 1200mm / min, and printing is performed according to the slice file in the 3D printer to obtain a silicon nitride ceramic embryo;

[0080] Perform vacuum debinding treatment, raise the temperature of the silicon nitride ceramic body in the previous step to 400°C in a vacuum furnace at a rate of 0.3°C / min, and pre-sinter for 2h to remove organic matter;

[0081] Performing an air decarbonization step, heating the silicon nitride ceramic body in the previous step to 600° C. at a rate of 10° C. / min in a muffle furnace, and pre-firing for 1 hour to remove carbon residues of organic matter;

[0082] The silicon nitride ceramic body is sintered by heating the temperature of the silicon nitride ceramic body in the previous step to 1900° C. at a rate of 5° C. / min and sintering for 2 h to obtain silicon nitride ceramics.

[0083] The preparation method of Example 2 is basically the same as that of Example 1, except that the mass ratio of the coarse silicon nitride powder to the fine silicon nitride powder is 2:8.

[0084] The preparation method of Example 3 is basically the same as that of Example 1, except that the mass ratio of the coarse silicon nitride powder to the fine silicon nitride powder is 3:7.

[0085] The preparation method of Example 4 is basically the same as that of Example 1, except that the mass ratio of the coarse silicon nitride powder to the fine silicon nitride powder is 4:6.

[0086] The preparation method of Comparative Example 1 is substantially the same as that of Example 1, except that only coarse silicon nitride powder is included.

[0087] The preparation method of Comparative Example 2 is substantially the same as that of Example 1, except that only silicon nitride fine powder is included.

[0088] Mechanical tests were performed on the above-mentioned Examples 1 to 4 and Comparative Examples 1 to 2, and the test results are as follows:

[0089] Table 1 Test results of 10 parallel samples corresponding to Example 1

[0090]

[0091] Table 2 Test results of 10 parallel samples corresponding to Example 2

[0092]

[0093] Table 3 Test results of 10 parallel samples corresponding to Example 3

[0094]

[0095] Table 4 Test results of 10 parallel samples corresponding to Example 4

[0096]

[0097] Table 5 Test results of 10 parallel samples corresponding to comparative example 1

[0098]

[0099] Table 6 Mechanical test results corresponding to different embodiments and comparative examples

[0100]

[0101] The test results in Table 6 represent the average values ​​of 10 parallel samples corresponding to each embodiment or comparative example.

[0102] According to Tables 1 to 6, it is found that compared with the silicon nitride ceramics prepared by 3D printing ceramic slurry including only coarse silicon nitride powder or fine silicon nitride powder, the silicon nitride ceramics prepared in the embodiment of the present application have higher mechanical properties, the bending strength can reach 400MPa to 600MPa, and the fracture toughness can reach 5MPa·m 1 / 2 ~7MPa·m 1 / 2 , which can meet the use requirements of harsh environments. Under the requirements of photocuring ceramic slurry, although the sample including only coarse silicon nitride powder is easier to achieve high solid content, the mechanical properties are not good; and the slurry prepared only with fine silicon nitride powder in Comparative Example 2 cannot print out the corresponding sample, because the fine silicon nitride powder is easy to agglomerate, resulting in the inability to form the sample. The embodiment of the present application combines coarse silicon nitride powder and fine silicon nitride powder for grading and adjustment to obtain silicon nitride ceramics with both high solid content and excellent mechanical properties, which significantly improves the comprehensive performance of photocuring silicon nitride ceramic slurry and effectively overcomes the problems of low solid content, excessive sedimentation rate, and insufficient mechanical properties of silicon nitride ceramic slurry. In addition, according to Tables 1 to 4, it is not difficult to find that the quality fluctuation of silicon nitride ceramics prepared in the embodiment of the present application is small, which provides technical guarantee for the efficient and precise manufacturing of high-performance silicon nitride ceramics.

[0103] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present application, and in practical applications, various changes may be made to the embodiments in form and detail without departing from the spirit and scope of the present application. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present application, and therefore the scope of protection of the present application shall be subject to the scope defined in the claims.

Claims

1. A 3D printing ceramic slurry, characterized in that: include: Inorganic powder, the inorganic powder comprises silicon nitride coarse powder and silicon nitride fine powder, the average particle size of the silicon nitride coarse powder is 1 μm to 1.5 μm, the average particle size of the silicon nitride fine powder is 0.1 μm to 0.7 μm, and the mass ratio of the silicon nitride coarse powder to the silicon nitride fine powder is 1:9 to 4:6; Photosensitive resin, the inorganic powder accounts for 30vol% to 50vol% of the total solid content of the inorganic powder and the photosensitive resin; Dispersant, the mass ratio of the dispersant to the inorganic powder is 0.01 to 0.08; The photoinitiator has a mass ratio of 0.015 to 0.05 to the photosensitive resin.

2. The 3D printing ceramic slurry according to claim 1, characterized in that: The inorganic powder also includes yttrium oxide and magnesium oxide. The mass fractions of the substances in the inorganic powder are as follows: the mass fraction of the silicon nitride coarse powder and the silicon nitride fine powder is 75 to 85 parts in total, the mass fraction of yttrium oxide is 5 to 15 parts, and the mass fraction of magnesium oxide is 5 to 15 parts.

3. The 3D printing ceramic slurry according to claim 2, characterized in that: The total mass of the yttrium oxide and the magnesium oxide accounts for 5% to 20% of the total mass of the inorganic powder.

4. A method for preparing a 3D printing ceramic slurry, characterized in that: include: Weigh silicon nitride coarse powder, silicon nitride fine powder, photosensitive resin, dispersant and photoinitiator according to the 3D printing ceramic slurry according to any one of claims 1 to 3; The silicon nitride coarse powder and the silicon nitride fine powder are mixed with an ethanol solution and then subjected to a first ball milling process to obtain a premix, wherein the silicon nitride coarse powder and the silicon nitride fine powder together account for 30 vol% to 50 vol% of the solid content of the silicon nitride coarse powder, the silicon nitride fine powder and the ethanol solution; The premix is ​​dried and ground to obtain an inorganic mixed powder; Mixing the inorganic mixed powder with the photosensitive resin to obtain a premixed liquid; Adding the photoinitiator and the dispersant into the premixed liquid for a second ball milling process to obtain an initial slurry; The initial slurry is filtered through a sieve to obtain the target slurry.

5. The method for preparing 3D printing ceramic slurry according to claim 4, characterized in that: The rotation speed of the first ball milling treatment is 100 r / min to 200 r / min, and the time is 8 h to 10 h; the rotation speed of the second ball milling treatment is 1000 r / min to 2000 r / min, and the time is 10 h to 12 h.

6. The method for preparing a 3D printing ceramic slurry according to claim 4, characterized in that: The drying process is carried out at a temperature of 80° C. to 100° C. and for a time of 10 h to 12 h.

7. The method for preparing a 3D printing ceramic slurry according to claim 4, characterized in that: The mesh number of the sieve is 100-300 meshes.

8. The method for preparing 3D printing ceramic slurry according to claim 4, characterized in that: The grinding process lasts for 30 to 40 minutes.

9. A method for preparing silicon nitride ceramics, characterized in that: include: The 3D printing ceramic slurry according to any one of claims 1 to 3 is used as a raw material, or the target slurry prepared by the preparation method of the 3D printing ceramic slurry according to any one of claims 4 to 8 is used as a raw material, and a silicon nitride ceramic body is prepared by printing layer by layer by a 3D printer, and the exposure intensity of the 3D printer printing is 60mW / cm 2 ~150mW / cm 2 , the exposure time of the bottom layer is 1s~4s, the exposure time of the normal layer is 3s~6s, the printed layer thickness is 30μm~60μm, and the scraper speed is 600mm / min~1800mm / min; Performing vacuum debinding treatment, heating the silicon nitride ceramic body in a vacuum furnace at a rate of 0.1°C / min to 0.5°C / min to 300°C to 500°C, and then keeping the temperature for 1h to 3h; Performing air decarbonization treatment, heating the silicon nitride ceramic body in a muffle furnace at a rate of 5°C / min to 15°C / min to 500°C to 700°C, and then keeping the temperature for 0.5h to 1.5h; The silicon nitride ceramic body is subjected to sintering treatment, wherein the temperature is raised to 1800° C. to 2000° C. at a rate of 1° C. / min to 10° C. / min and then sintered for 1 hour to 3 hours.

10. Use of the 3D printing ceramic slurry according to any one of claims 1 to 3 in 3D printing technology.

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