Preparation method of 3D printing ceramic slurry and ceramic shaping method

Abstract

The invention provides a preparation method of 3D printing ceramic slurry and a ceramic shaping method, and the preparation method of the 3D printing ceramic slurry comprises the following steps: S1, loading nano-scale silicon dioxide on the surface of micro-nano-scale aluminum oxide to obtain nano-silicon dioxide modified aluminum oxide; s2, coating the surface of the nano silicon dioxide modified aluminum oxide with aluminum hydroxide to obtain modified aluminum oxide; and S3, ball-milling and mixing the modified aluminum oxide and a dispersing agent, and then mixing and stirring with a binder, an auxiliary agent and a solvent. The 3D printing ceramic slurry provided by the invention can realize high solid content, has good dispersibility and fluidity, is strong in stability, is not liable to cause problems of layering, precipitation and the like, the surface smoothness of extruded silk threads is high, and a prepared ceramic product is high in strength.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramics, and particularly relates to a preparation method of a 3D printing ceramic slurry and a ceramic solidification method. Background Art

[0002] Due to excellent properties such as high hardness, high wear resistance, high temperature resistance, oxidation resistance, corrosion resistance, and good chemical stability, ceramic materials are listed as the three major solid materials today together with metal materials and polymer materials. However, due to the extremely high hardness and brittleness of ceramic materials, there are problems such as high cost and low processing efficiency in machining; furthermore, traditional forming processes greatly limit the application and development of ceramic products with complex structures.

[0003] In recent years, rapid prototyping processes for ceramic products have become a research hotspot due to advantages such as no need for molds, short manufacturing cycles, and low costs. The ceramic direct writing forming technology has a simple process, is easy to operate, and has low equipment costs. The slurry suitable for this technology needs to have the ability to solidify to maintain the printed shape. However, currently, the slurry suitable for this forming method has poor dispersibility and fluidity; at the same time, most of the prepared ceramic slurries do not consider the problem of easy storage. Generally, problems such as stratification and precipitation occur after a long storage time, resulting in the need to re-prepare the slurry, causing waste of time and raw materials. Summary of the Invention

[0004] In order to solve the above problems and overcome the above deficiencies in the prior art, the present invention provides a preparation method of a 3D printing ceramic slurry and a ceramic solidification method. The 3D printing ceramic slurry of the present invention can achieve a high solid content while having good dispersibility and fluidity, strong stability, not easily prone to problems such as stratification and precipitation, the extruded wire has a high surface smoothness, and the prepared ceramic product has high strength.

[0005] To achieve the above objectives, the present invention is realized through the following technical solutions: A preparation method of a 3D printing ceramic slurry, comprising the following steps: S1. Load nanoscale silica on the surface of micro-nano alumina to obtain nano-silica modified alumina; S2. Coat aluminum hydroxide on the surface of the nano-silica modified alumina to obtain modified alumina; S3. After ball-milling and mixing the modified alumina with a dispersant, then mix and stir it with a binder, an auxiliary agent, and a solvent to prepare the 3D printing ceramic slurry.

[0006] Preferably, step S1 specifically includes the following steps: placing micro-nano alumina in nano-silica sol, stirring and mixing for 0.5 - 1 h, then performing ultrasonic dispersion for 0.5 - 1 h, then filtering, drying in a vacuum drying oven, then placing it in a roasting furnace, heating to 420 - 450 °C and roasting for 1 - 1.5 h, cooling to room temperature, and obtaining nano-silica modified alumina through grinding and dispersion.

[0007] Preferably, the solid content of the nano-silica sol is 20 - 25%, the particle size of nano-silica in the nano-silica sol is 10 - 30 nm; the particle size of the micro-nano alumina is 0.5 - 1 μm.

[0008] Preferably, step S2 specifically includes the following steps: dispersing nano-silica modified alumina in an ethanol / water mixed solution, cooling to 1 - 5 °C, performing ultrasonic treatment for 1 - 3 h, then slowly dropping an aluminum nitrate aqueous solution while stirring, and adding ammonia water during the dropping of the aluminum nitrate aqueous solution to keep the pH value of the reaction system between 8.5 - 9.5; after the dropping of the aluminum nitrate aqueous solution is completed, continuously stir for 3 - 6 h, then filter and wash, and then perform vacuum drying to obtain modified alumina.

[0009] Preferably, in the ethanol / water mixed solution, the volume ratio of ethanol to water is 1:0.5 - 1; the concentration of the aluminum nitrate aqueous solution is 0.01 - 0.02 mol / L; the volume ratio of nano-silica modified alumina, ethanol / water mixed solution, and aluminum nitrate aqueous solution is 1:50 - 70:0.5 - 1.

[0010] Preferably, the 3D printing ceramic slurry comprises the following raw materials in parts by weight: 60 - 70 parts of modified alumina, 2 - 5 parts of dispersant, 9 - 12 parts of binder, 0.5 - 1 part of auxiliary agent, and 10 - 20 parts of solvent.

[0011] Preferably, the dispersant includes any one of oleic acid, citric acid, and polyethylene glycol, the binder is polyvinylpyrrolidone; the solvent is one of ethanol or deionized water; the auxiliary agent is fumed silica.

[0012] Specifically, the polyvinylpyrrolidone used in the present invention is PVP K30; the fumed silica is Cabot hydrophilic fumed silica, and the product number is LM150.

[0013] As a general inventive concept, the present invention provides a method for forming a ceramic solid, including the following steps: layer-by-layer printing and forming the 3D printing ceramic slurry through a DIW inkjet direct writing 3D printer to obtain a green ceramic body; transferring the green ceramic body to a sintering furnace under vacuum or inert gas for sintering to obtain a ceramic product;

[0014] The 3D printing ceramic slurry is the 3D printing ceramic slurry prepared by the above preparation method.

[0015] Preferably, the printing rate of the DIW ink direct writing 3D printer is 20-50 mm / s; the inner diameter of the needle of the 3D printer is 1.4-1.8 mm.

[0016] Preferably, during sintering, first heat up at a heating rate of 2-5 °C / min to 260-300 °C, keep warm for 30-90 min, then heat up at a heating rate of 8-15 °C / min to 900-950 °C, keep warm for 50-120 min, and then heat up at a heating rate of 2-5 °C / min to 1250-1350 °C, keep warm for 2-8 h.

[0017] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: 1. The ceramic powder used in the present invention is micro-nano alumina. By loading nano-silica on its surface, the surface roughness can be significantly improved. The improvement of this roughness is beneficial to promoting the dispersibility of alumina. At the same time, aluminum hydroxide is coated on the surface of the obtained nano-silica modified alumina. Hydrogen bonds are formed between aluminum hydroxide and the solvent (water or ethanol), and hydrogen bond interactions also occur between alumina particles. As a result, alumina can reduce agglomeration, be more uniformly and stably dispersed in the solvent, and when combined with other raw materials, the 3D printing ceramic slurry has good dispersibility and fluidity while achieving a high solid content, has a long storage period, and is not prone to problems such as delamination and precipitation.

[0018] 2. In the present invention, nano-silica and aluminum hydroxide are successively coated on the surface of alumina. During the sintering process, aluminum hydroxide decomposes into highly active transition alumina, reducing the sintering activation energy. Subsequently, the nano-alumina generated by sintering can fill the gaps, enhance the contact between particles, and promote tissue densification. During the subsequent temperature increase process, the nano-silica on the surface of alumina can enhance the interfacial diffusion and promote the formation of sintering necks, enabling the obtained ceramic products to have a finer microstructure and an overall strength improvement.

[0019] 3. By optimizing the composition and ratio of the 3D printing ceramic slurry, the present invention can complete rapid surface solidification and realize the direct ink writing 3D printing of high-solid-phase materials. The 3D printing ceramic slurry of the present invention is simple to prepare, has few component types, has good dispersibility and fluidity while achieving a high solid content, has strong stability, is not prone to problems such as delamination and precipitation, has a high surface smoothness of the extruded wire, and the obtained ceramic products have high strength. The 3D printing ceramic slurry is combined with a suitable sintering process to prepare ceramic products with good shape retention and high strength. The present invention can realize the fine and diversified manufacturing of alumina ceramics and has potential application prospects in multiple fields. Description of the Drawings

[0020] The accompanying drawings are used to provide a further understanding of the present invention and form a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention.

[0021] Figure 1 It is a picture of the printing process of the 3D printing ceramic slurry in Embodiment 6 of the present invention.

[0022] Figure 2 It is a scanning electron microscope picture of the ceramic product prepared in Embodiment 6 of the present invention. Detailed Embodiments

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without any creative efforts shall fall within the scope of protection of the present invention.

[0024] Embodiment 1: A method for preparing a 3D printing ceramic slurry, comprising the following steps: S1. Place alumina with a particle size of 0.5 - 1 μm in a nano-silica sol with a solid content of 20% (the particle size of nano-silica in the sol is 10 - 30 nm). After stirring and mixing for 1 h, then ultrasonically disperse for 1 h, and then filter. Place it in a vacuum drying oven and vacuum dry at 60 °C, and then place it in a roasting furnace, heat up to 425 °C and roast for 1 h, cool to room temperature, and obtain nano-silica modified alumina after grinding and dispersion.

[0025] S2. Disperse the nano-silica modified alumina in an ethanol / water mixture, cool down to 2 °C, and ultrasonically treat for 2 h. Then, while stirring, slowly dropwise add an aluminum nitrate aqueous solution with a concentration of 0.015 mol / L, and add ammonia water during the dropping of the aluminum nitrate aqueous solution to keep the pH value of the reaction system between 8.5 - 9.5. After the dropping of the aluminum nitrate aqueous solution is completed, continue to stir for 5 h, and then filter, wash, and then vacuum dry to obtain modified alumina (i.e., nano-silica modified alumina coated with aluminum hydroxide).

[0026] Among them, in the ethanol / water mixture, the volume ratio of ethanol to water is 1:1; the volume ratio of nano-silica modified alumina, ethanol / water mixture, and aluminum nitrate aqueous solution is 1:60:0.8.

[0027] S3. After ball-milling and mixing 130 g of modified alumina with 6 g of citric acid, mix it with 20 g of polyvinylpyrrolidone, 2 g of fumed silica, and 35 g of deionized water in a vacuum pug mill to obtain a 3D printing ceramic slurry.

[0028] Example 2: A method for preparing a 3D printing ceramic slurry, comprising the following steps: S1. Place alumina with a particle size of 0.5 - 1 μm in a nano-silica sol with a solid content of 25% (the particle size of nano-silica in the sol is 10 - 30 nm), stir and mix for 0.5 h, then ultrasonically disperse for 1 h, then filter, place in a vacuum drying oven and vacuum dry at 60 °C, then place in a roasting furnace, heat up to 450 °C and roast for 1 h, cool to room temperature, and obtain nano-silica modified alumina through grinding and dispersion.

[0029] S2. Disperse the nano-silica modified alumina in an ethanol / water mixture, cool to 1 °C, ultrasonically treat for 3 h, then slowly drip a 0.01 mol / L aluminum nitrate aqueous solution while stirring, and add ammonia water during the dripping of the aluminum nitrate aqueous solution to keep the pH value of the reaction system between 8.5 - 9.5; after the dripping of the aluminum nitrate aqueous solution is completed, continue to stir for 3 h, then filter, wash, and then vacuum dry to obtain modified alumina.

[0030] Among them, in the ethanol / water mixture, the volume ratio of ethanol to water is 1:0.5; the volume ratio of nano-silica modified alumina, ethanol / water mixture, and aluminum nitrate aqueous solution is 1:50:1.

[0031] S3. After ball-milling and mixing 125 g of modified alumina with 8 g of citric acid, mix it with 18 g of polyvinylpyrrolidone, 1 g of fumed silica, and 30 g of deionized water in a vacuum pug mill to obtain a 3D printing ceramic slurry.

[0032] Example 3: A method for preparing a 3D printing ceramic slurry, comprising the following steps: S1. Place alumina with a particle size of 0.5 - 1 μm in a nano-silica sol with a solid content of 20% (the particle size of nano-silica in the sol is 10 - 30 nm), stir and mix for 1 h, then ultrasonically disperse for 0.5 h, then filter, place in a vacuum drying oven and vacuum dry at 60 °C, then place in a roasting furnace, heat up to 420 °C and roast for 1.5 h, cool to room temperature, and obtain nano-silica modified alumina through grinding and dispersion.

[0033] S2. Disperse the nano-silica modified alumina in the ethanol / water mixture, cool down to 5 °C, perform ultrasonic treatment for 1 h, then slowly dropwise add an aqueous aluminum nitrate solution with a concentration of 0.02 mol / L while stirring, and add ammonia water during the dropping of the aqueous aluminum nitrate solution to keep the pH value of the reaction system between 8.5 and 9.5; after the dropping of the aqueous aluminum nitrate solution is completed, continue stirring for 6 h, then perform filtration and washing, and then vacuum dry to obtain the modified alumina.

[0034] Among them, in the ethanol / water mixture, the volume ratio of ethanol to water is 1:1; the volume ratio of the nano-silica modified alumina, the ethanol / water mixture, and the aqueous aluminum nitrate solution is 1:70:0.5.

[0035] S3. After ball-milling and mixing 120 g of the modified alumina with 4 g of oleic acid, then place it together with 20 g of polyvinylpyrrolidone, 1 g of fumed silica, and 20 g of deionized water in a vacuum clay mixer for mixing and stirring to obtain the 3D printing ceramic slurry.

[0036] Example 4: A method for preparing a 3D printing ceramic slurry, comprising the following steps: S1. Prepare the nano-silica modified alumina by the method in Example 3.

[0037] S2. Prepare the modified alumina by the method in Example 3.

[0038] S3. After ball-milling and mixing 140 g of the modified alumina with 10 g of oleic acid, then place it together with 24 g of polyvinylpyrrolidone, 1.5 g of fumed silica, and 40 g of deionized water in a vacuum clay mixer for mixing and stirring to obtain the 3D printing ceramic slurry.

[0039] Example 5: A method for preparing a 3D printing ceramic slurry, comprising the following steps: S1. Prepare the nano-silica modified alumina by the method in Example 1.

[0040] S2. Prepare the modified alumina by the method in Example 1.

[0041] S3. After ball-milling and mixing 125 g of the modified alumina with 5 g of citric acid, then place it together with 22 g of polyvinylpyrrolidone, 2 g of fumed silica, and 30 g of deionized water in a vacuum clay mixer for mixing and stirring to obtain the 3D printing ceramic slurry.

[0042] Example 6: A method for solidifying ceramics, comprising the following steps: Step 1. Mix high-strength gypsum powder and deionized water in a ratio of 3:1 to make a gypsum board with a thickness of 10 mm; Step 2: After discharging the gas in the 3D printing ceramic slurry prepared in Example 1, load it into the syringe of a DIW ink direct writing 3D printer with a needle inner diameter of 1.7 mm. Place the gypsum board on the printing platform, set up the 3D printing program and start layer-by-layer printing at a printing rate of 30 mm / s. The printed three-dimensional structure is dried to obtain a green alumina ceramic body. Transfer the green alumina ceramic body to a vacuum sintering furnace for sintering. During sintering, first heat it up to 300 °C at a heating rate of 5 °C / min and hold for 60 min, then heat it up to 920 °C at a heating rate of 10 °C / min and hold for 80 min, and then heat it up to 1300 °C at a heating rate of 3 °C / min and hold for 5 h, and cool it down to room temperature with the furnace to obtain a ceramic product.

[0043] In this example, the pictures of the printing process of the 3D printing ceramic slurry are as Figure 1 shown, and the scanning electron microscope pictures of the prepared ceramic products are as Figure 2 shown.

[0044] Example 7: A method for forming ceramics includes the following steps: Step 1: Mix high-strength gypsum powder and deionized water in a ratio of 3:1 to make a gypsum board with a thickness of 10 mm; Step 2: After discharging the gas in the 3D printing ceramic slurry prepared in Example 3, load it into the syringe of a DIW ink direct writing 3D printer with a needle inner diameter of 1.5 mm. Place the gypsum board on the printing platform, set up the 3D printing program and start layer-by-layer printing at a printing rate of 35 mm / s. The printed three-dimensional structure is dried to obtain a green alumina ceramic body. Transfer the green alumina ceramic body to a vacuum sintering furnace for sintering. During sintering, first heat it up to 260 °C at a heating rate of 2 °C / min and hold for 50 min, then heat it up to 950 °C at a heating rate of 10 °C / min and hold for 60 min, and then heat it up to 1250 °C at a heating rate of 2 °C / min and hold for 3 h, and cool it down to room temperature with the furnace to obtain a ceramic product.

[0045] Example 8: A method for forming ceramics includes the following steps: Step 1: Mix high-strength gypsum powder and deionized water in a ratio of 3:1 to make a gypsum board with a thickness of 10 mm; Step 2: After discharging the gas in the 3D printing ceramic slurry prepared in Example 2, load it into the syringe of a DIW ink direct writing 3D printer with a needle inner diameter of 1.5 mm. Place the gypsum board on the printing platform, set up the 3D printing program and start layer-by-layer printing at a printing rate of 50 mm / s. The printed three-dimensional structure is dried to obtain a green alumina ceramic body. Transfer the green alumina ceramic body to a vacuum sintering furnace for sintering. During sintering, first heat it up to 280 °C at a heating rate of 5 °C / min, hold for 60 min, then heat it up to 900 °C at a heating rate of 13 °C / min, hold for 120 min, and then heat it up to 1350 °C at a heating rate of 2 °C / min, hold for 2 h, and cool it down to room temperature with the furnace to obtain the ceramic product.

[0046] Comparative Example 1: Different from Example 1, the modified alumina was replaced with alumina having a particle size of 0.5 - 1 μm.

[0047] Comparative Example 2: Different from Example 1, the preparation method of the modified alumina includes the following steps: Disperse alumina with a particle size of 0.5 - 1 μm in an ethanol / water mixed solution, cool it down to 2 °C, and perform ultrasonic treatment for 2 h. Then, while stirring, slowly dropwise add an aluminum nitrate aqueous solution with a concentration of 0.015 mol / L, and add ammonia water during the dropping of the aluminum nitrate aqueous solution to keep the pH value of the reaction system between 8.5 - 9.5. After the dropping of the aluminum nitrate aqueous solution is completed, continue stirring for 5 h, then filter, wash, and then perform vacuum drying to obtain the modified alumina (i.e., alumina coated with aluminum hydroxide).

[0048] Among them, in the ethanol / water mixed solution, the volume ratio of ethanol to water is 1:1; the volume ratio of alumina, ethanol / water mixed solution, and aluminum nitrate aqueous solution is 1:60:0.8.

[0049] Comparative Example 3: Different from Example 1, the modified alumina is the nano-silica modified alumina prepared in Step S1, and no aluminum hydroxide coating is performed.

[0050] Comparative Example 4: Different from Example 1, in Step S2, the volume ratio of nano-silica modified alumina, ethanol / water mixed solution, and aluminum nitrate aqueous solution is 1:60:0.1.

[0051] Comparative Example 5: Different from Example 1, in Step S2, the volume ratio of nano-silica modified alumina, ethanol / water mixed solution, and aluminum nitrate aqueous solution is 1:60:4.

[0052] Comparative Example 6: Different from Example 6, the 3D printing ceramic slurry is the 3D printing ceramic slurry prepared in Comparative Example 1.

[0053] Comparative Example 7: Different from Example 6, the 3D printing ceramic slurry is the 3D printing ceramic slurry prepared in Comparative Example 2.

[0054] Comparative Example 8: Different from Example 6, the 3D printing ceramic slurry is the 3D printing ceramic slurry prepared in Comparative Example 3.

[0055] Comparative Example 9: Different from Example 6, the 3D printing ceramic slurry is the 3D printing ceramic slurry prepared in Comparative Example 4.

[0056] Comparative Example 10: Different from Example 6, the 3D printing ceramic slurry is the 3D printing ceramic slurry prepared in Comparative Example 5.

[0057] Test: 1. Seal the 3D printing ceramic slurries in Examples 1 - 5 and Comparative Examples 1 - 5 and place them at 2 - 4 °C for 20 days, and observe the problems of stratification and precipitation. The specific results are shown in Table 1.

[0058] Table 1: Stratification condition Precipitation condition Example 1 No stratification No precipitation Example 2 No stratification No precipitation Example 3 No stratification No precipitation Example 4 No stratification No precipitation Example 5 No stratification No precipitation Comparative example 1 Moderate stratification More precipitation Comparative example 2 No stratification A little precipitation Comparative example 3 Slight stratification A little precipitation Comparative example 4 No stratification No precipitation Comparative example 5 No stratification No precipitation As can be seen from Table 1, the 3D printing ceramic slurries in Examples 1 - 5 and Comparative Examples 1 - 5 have good stability, with almost no stratification and precipitation.

[0059] Comparing Example 1 with Comparative Example 1, it can be seen that if alumina is not modified at all, there will be obvious stratification and a large amount of precipitation. Comparing Example 1 with Comparative Example 2, it can be seen that if nano - silica is not used to modify alumina, there is no stratification but there will be a little precipitation; comparing Example 1 with Comparative Example 3, it can be seen that if sodium hydroxide - coated nano - silica is not used, there will be a little precipitation and slight stratification.

[0060] 2. Test the flexural strength of the ceramic products in Examples 6 - 8 and Comparative Examples 6 - 10. The test standard is ASTM C1161, and the specific test results are shown in Table 2.

[0061] Table 2: Flexural strength / MPa Example 6 467 Example 7 455 Example 8 471 Comparative example 6 382 Comparative example 7 422 Comparative example 8 416 Comparative example 9 431 Comparative example 10 401 As can be seen from Table 2, the ceramic products in Examples 6 - 8 generally have a high flexural strength. Comparing Example 6 with Comparative Example 6, it can be seen that if alumina is not modified at all, its flexural strength will be significantly reduced.

[0062] It can be seen from the comparison between Example 6 and Comparative Examples 7-8 that if nano-silica or aluminum hydroxide is not used to modify alumina, the flexural strength will decrease. It can be seen from the comparison between Example 6 and Comparative Examples 9-10 that when aluminum hydroxide coating is carried out, if the coating amount is too small, the strength will decrease, and if the coating amount is too large, the flexural strength will be significantly reduced.

[0063] The above embodiments are only the preferred embodiments of the present invention, and do not limit the protection scope of the present invention. Any changes made by adopting the design principle of the present invention and non-creative labor on this basis shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a 3D printing ceramic slurry, characterized in that, It includes the following steps: S1. Load nanoscale silica on the surface of micro-nano alumina to obtain nano-silica modified alumina; S2. Coating aluminum hydroxide on the surface of nano-silica modified alumina to obtain modified alumina; S3. After ball-milling and mixing the modified alumina with a dispersant, then mixing and stirring it with a binder, an additive, and a solvent to prepare the 3D printing ceramic slurry.

2. The preparation method of the 3D printing ceramic slurry according to claim 1, wherein, Step S1 specifically includes the following steps: Place the micro-nano alumina in the nano-silica sol, stir and mix for 0.5 - 1 h, then ultrasonically disperse for 0.5 - 1 h, then filter, place it in a vacuum drying oven for drying, then place it in a roasting furnace, heat up to 420 - 450 °C and roast for 1 - 1.5 h, cool to room temperature, and obtain nano-silica modified alumina through grinding and dispersion.

3. The preparation method of the 3D printing ceramic slurry according to claim 2, wherein, The solid content of the nano-silica sol is 20 - 25%, and the particle size of the nano-silica in the nano-silica sol is 10 - 30 nm; the particle size of the micro-nano alumina is 0.5 - 1 μm.

4. The preparation method of the 3D printing ceramic slurry according to claim 1, wherein, Step S2 specifically includes the following steps: Disperse the nano-silica modified alumina in an ethanol / water mixed solution, cool down to 1 - 5 °C, ultrasonically treat for 1 - 3 h, then slowly dropwise add an aluminum nitrate aqueous solution while stirring, and add ammonia water during the dropping of the aluminum nitrate aqueous solution to keep the pH value of the reaction system between 8.5 - 9.5; after the dropping of the aluminum nitrate aqueous solution is completed, continue to stir for 3 - 6 h, then filter, wash, and then obtain the modified alumina through vacuum drying.

5. The preparation method of the 3D printing ceramic slurry according to claim 4, characterized in that, In the ethanol / water mixed solution, the volume ratio of ethanol to water is 1:0.5 - 1; the concentration of the aluminum nitrate aqueous solution is 0.01 - 0.02 mol / L; the volume ratio of the nano-silica modified alumina, the ethanol / water mixed solution, and the aluminum nitrate aqueous solution is 1:50 - 70:0.5 - 1.

6. The preparation method of the 3D printing ceramic slurry according to claim 1, wherein The 3D printing ceramic slurry includes the following raw materials in parts by weight: 60 - 70 parts of modified alumina, 2 - 5 parts of dispersant, 9 - 12 parts of binder, 0.5 - 1 part of additive, and 10 - 20 parts of solvent.

7. The preparation method of the 3D printing ceramic slurry according to claim 6, characterized in that, The dispersant includes any one of oleic acid, citric acid, and polyethylene glycol, the binder is polyvinylpyrrolidone; the solvent is one of ethanol or deionized water; the additive is fumed silica.

8. A ceramic solidification method, characterized in that, It includes the following steps: Layer-by-layer print and form the 3D printing ceramic slurry through a DIW ink direct writing 3D printer to obtain a green ceramic body; transfer the green ceramic body to a sintering furnace under vacuum or inert gas for sintering to obtain a ceramic product; The 3D printing ceramic slurry is the 3D printing ceramic slurry prepared by the preparation method described in any one of claims 1 - 7.

9. The pottery solidification method according to claim 8, characterized in that, The printing rate of the DIW ink direct writing 3D printer is 20 - 50 mm / s; the inner diameter of the needle of the 3D printer is 1.4 - 1.8 mm.

10. The ceramic solidification method according to claim 8, wherein During sintering, first heat up at a heating rate of 2 - 5 °C / min to 260 - 300 °C, hold for 30 - 90 min, then heat up at a heating rate of 8 - 15 °C / min to 900 - 950 °C, hold for 50 - 120 min, and then heat up at a heating rate of 2 - 5 °C / min to 1250 - 1350 °C, hold for 2 - 8 h.

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