Photo-cured aluminum oxide ceramic slurry and preparation method thereof

Abstract

The invention relates to the technical field of materials, in particular to light-cured aluminum oxide ceramic slurry and a preparation method thereof. The preparation method of the light-cured aluminum oxide ceramic slurry comprises the following preparation steps: preparation of alkenyl chitosan nanofibers, preparation of modified monomers, preparation of clathrate powder, preparation of a photosensitive resin premixed solution, preparation of clathrate powder and preparation of the light-cured aluminum oxide ceramic slurry. According to the preparation method, by introducing the alkenyl chitosan nanofiber and the inclusion compound powder, the rheological property, the sintering compactness and the mechanical property of the light-cured aluminum oxide ceramic slurry are remarkably improved, meanwhile, the apparent porosity and the shrinkage rate are reduced, and the preparation method is suitable for preparing the high-performance ceramic core.

Description

Technical Field

[0001] The present invention relates to the technical field of materials, and particularly to a photocurable alumina ceramic slurry and a preparation method thereof. Background Art

[0002] With the more stringent requirements of aeroengines for thrust-to-weight ratio and fast-cooling technology, the structure of aeroengine turbine blades has gradually tended to be precise and complex. As a consumable for forming the inner cavity structure of hollow blades, the surface quality, dimensional accuracy, high-temperature performance, etc. of ceramic cores have a direct impact on the qualification rate of blade production and manufacturing.

[0003] The photocurable 3D printing technology is a new type of ceramic forming technology with high forming accuracy and speed. Its principle is that through the selective irradiation of ultraviolet light, under the action of a photoinitiator, the monomers in the slurry composed of ceramic powder and photocurable resin are caused to undergo a polymerization reaction. After curing, a three-dimensional network is formed to wrap the ceramic particles and form a green body of a certain size and shape, and then the corresponding ceramic part is obtained through debinding and sintering. Therefore, the solid content and quality of the photocurable ceramic slurry are important factors directly affecting various performances of the ceramic part.

[0004] The patent technical document CN115043658B discloses a preparation method of photocurable ceramic slurry, which includes mixing surface-modified ceramic powder, photosensitive resin, and a dispersant to prepare ceramic slurry. The surface of the ceramic powder is modified by a modifier to make the ceramic powder have a certain affinity with the resin, and the viscosity of the slurry is effectively reduced by the combined use of a suitable dispersant, and a ceramic slurry with a high solid content and excellent fluidity can be obtained. The patent technical document CN111269007A discloses a ceramic photocurable slurry and a preparation method thereof, and the obtained slurry has better storage stability, which can ensure that the slurry has a sufficiently high anti-settling property and avoid adverse phenomena such as uneven printing performance caused by slurry settlement during the printing process. However, for the ceramic slurry for photocurable 3D printing, it must have good fluidity. Therefore, the slurry often has a low solid content, but the low solid content will lead to poor performance of the sintered formed part, and even phenomena such as shrinkage and collapse may occur. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a photocurable alumina ceramic slurry and a preparation method thereof to solve the problem that traditional ceramic slurries cannot have both good fluidity and high solid content at the same time.

[0006] Based on the above purpose, the present invention provides a preparation method of a photocurable alumina ceramic slurry, including the following steps:

[0007] S1: Disperse chitosan nanofibers in an ethanol solution, and ultrasonically treat until uniform. Then add silane coupling agent KH570, adjust the pH to 4 - 5, and stir at 60 - 70 °C for 4 - 5 h. Centrifuge, wash, and dry to obtain alkenylated chitosan nanofibers;

[0008] In step S1, the dosage ratio of the chitosan nanofibers, ethanol solution, and silane coupling agent KH570 is 1 - 2 g: 100 - 150 ml: 1 - 2 ml;

[0009] S2: Disperse trimethylolpropane triacrylate and alkenylated chitosan nanofibers in deionized water, stir evenly, then add ammonium persulfate and TEMED, and react at 25 - 30 °C for 1 - 2 h. Wash, freeze-dry, and crush to obtain a modified monomer;

[0010] In step S2, the dosage ratio of trimethylolpropane triacrylate, alkenylated chitosan nanofibers, ammonium persulfate, and TEMED is 0.3 - 0.5 g: 0.3 - 0.5 g: 0.04 - 0.05 g: 0.02 - 0.03 g;

[0011] S3: Disperse aluminum nanoparticles in deionized water, stir evenly and then heat. Slowly add sodium alginate during the heating process, and cool to room temperature after complete dissolution to obtain an aluminum - sodium alginate mixture. Subsequently, dissolve chitosan and anhydrous calcium chloride in a 1 wt% acetic acid aqueous solution to obtain a chitosan - calcium chloride mixed solution. Then, dropwise add the aluminum - sodium alginate mixture into the chitosan - calcium chloride mixed solution, let it stand for 12 h, filter, wash, and freeze-dry to obtain an inclusion complex powder;

[0012] In step S3, the dosage ratio of the aluminum nanoparticles, deionized water, sodium alginate, chitosan, anhydrous calcium chloride, and acetic acid aqueous solution is 5 - 6 g: 95 - 100 g: 0.8 - 1 g: 1.5 - 2 g: 2 - 3 g: 100 ml;

[0013] S4: Mix polyurethane acrylate, 1,6 - hexanediol diacrylate, dipropylene glycol diacrylate, trimethylolpropane triacrylate, modified monomer, photoinitiator TPO - L, dispersant BYK111, and inclusion complex powder. Then magnetically stir the mixture at a speed of 600 rpm for 2 h and let it stand for 24 h to obtain a photosensitive resin premix;

[0014] In step S4, the dosage ratio of polyurethane acrylate, 1,6 - hexanediol diacrylate, dipropylene glycol diacrylate, trimethylolpropane triacrylate, modified monomer, initiator TPO - L, dispersant BYK111, and inclusion complex powder is 100 - 150 g: 60 - 90 g: 30 - 45 g: 5 - 10 g: 5 - 6 g: 6 - 9 g: 6 - 10 g: 3 - 5 g;

[0015] S5: Ball mill the alumina powder, zirconia, chromium oxide and sintering aid, and grind through a 100-mesh sieve to obtain ceramic powder.

[0016] S6: Premix the ceramic powder and the photosensitive resin premix solution through a homogenizer for high-speed mixing, and then use a vacuum degassing machine to degas and defoam the slurry to obtain a photocurable alumina ceramic slurry.

[0017] Preferably, in step S1, the diameter of the chitosan nanofibers is 30 - 50 nm and the length is 2 μm.

[0018] Preferably, in step S3, the particle size of the aluminum nanoparticles is 50 - 100 nm.

[0019] Preferably, in step S3, the concentration of the acetic acid aqueous solution is 1 wt%.

[0020] Preferably, the polyurethane acrylate in step S4 is purchased from Shanghai Yinchang New Materials Co., Ltd.

[0021] Preferably, in step S5, the dosage ratio of the alumina powder, zirconia, chromium oxide, and sintering aid is 70 - 80 g: 10 - 15 g: 5 g: 5 g;

[0022] Preferably, the sintering aid in step S5 is composed of yttrium oxide, samarium oxide, and lanthanum oxide mixed in a weight ratio of 3: 1: 1.

[0023] Preferably, in step S5, the ball milling speed is 300 - 400 rpm and the time is 10 h.

[0024] Preferably, in step S6, the solid content of the photocurable alumina ceramic slurry is 55 - 58 vol%.

[0025] Preferably, in step S6, the speed of the homogenizer is 2500 - 3000 r / min and the mixing time is 3 min.

[0026] Advantages of the present invention: The photocurable alumina ceramic slurry of the present invention has a lower slurry viscosity and improved rheological properties, making the slurry easier to process and form.

[0027] The core obtained by printing and sintering the photocurable alumina ceramic slurry of the present invention has excellent mechanical strength, low open porosity, and shrinkage rate.

[0028] The photocurable alumina ceramic slurry of the present invention introduces chitosan nanofibers into the premixed solution by grafting and aluminum nanoparticles into the premixed solution by inclusion, so that the slurry has good fluidity, and the ceramic core obtained by using this slurry has obvious improvements in both flexural strength, open porosity and shrinkage rate. Detailed implementation mode

[0029] To make the purpose, technical solution and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with specific embodiments.

[0030] Example 1: A photocurable alumina ceramic slurry, and the specific preparation steps are as follows:

[0031] (1) Disperse 1 g of chitosan nanofibers in 100 ml of ethanol solution, and ultrasonically treat until uniform, then add 1 ml of silane coupling agent KH570, adjust the pH to 4, and stir at 60 °C for 4 h, centrifuge, wash, and dry to obtain vinylated chitosan nanofibers;

[0032] (2) Disperse 0.3 g of trimethylolpropane triacrylate and 0.3 g of vinylated chitosan nanofibers in deionized water, stir evenly, then add 0.04 g of ammonium persulfate and 0.02 g of TEMED, react at 25 °C for 1 h, wash twice with deionized water, freeze-dry, and crush to obtain a modified monomer;

[0033] (3) Disperse 5 g of aluminum nanoparticles in 95 g of deionized water, stir evenly and then heat, slowly add 0.8 g of sodium alginate during the heating process, and cool to room temperature after complete dissolution to obtain an aluminum-sodium alginate mixture; then dissolve 1.5 g of chitosan and 2 g of anhydrous calcium chloride in 100 ml of 1 wt% acetic acid aqueous solution to obtain a chitosan-calcium chloride mixed solution; then dropwise add the aluminum-sodium alginate mixture into the chitosan-calcium chloride mixed solution, let stand for 12 h, filter, wash, and freeze-dry to obtain an inclusion powder;

[0034] (4) Mix 100 g of polyurethane acrylate, 60 g of 1,6-hexanediol diacrylate, 30 g of dipropylene glycol diacrylate, 5 g of trimethylolpropane triacrylate, 5 g of modified monomer, 6 g of photoinitiator TPO-L, 6 g of dispersant BYK111, and 3 g of inclusion powder, and then magnetically stir the mixture at a speed of 600 rpm for 2 h, and let stand for 24 h to obtain a photosensitive resin premixed solution;

[0035] (5) Ball-mill 70 g of alumina powder, 10 g of zirconia, 5 g of chromium oxide and 5 g of sintering aid at a rotation speed of 300 rpm for 10 h, and grind through a 100-mesh sieve to obtain ceramic powder;

[0036] (6) Premix the ceramic powder and the photosensitive resin premix solution through a homogenizer for high-speed mixing, and then use a vacuum defoaming machine to degas and defoam the slurry for 15 minutes to obtain a photocurable alumina ceramic slurry with a solid content of 55 vol%. Among them, the rotation speed of the homogenizer is 2500 r / min, and the mixing time is 3 minutes.

[0037] Example 2: A photocurable alumina ceramic slurry, and the specific preparation steps are as follows:

[0038] (1) Disperse 1.5 g of chitosan nanofibers in 130 ml of ethanol solution, and ultrasonically treat until uniform. Then add 1.5 ml of silane coupling agent KH570, adjust the pH to 4.4, and stir at 65 °C for 5 h. Centrifuge, wash, and dry to obtain vinylated chitosan nanofibers;

[0039] (2) Disperse 0.4 g of trimethylolpropane triacrylate and 0.4 g of vinylated chitosan nanofibers in deionized water, stir evenly, then add 0.05 g of ammonium persulfate and 0.03 g of TEMED, react at 30 °C for 2 h, wash twice with deionized water, freeze-dry, and crush to obtain a modified monomer;

[0040] (3) Disperse 5.5 g of aluminum nanoparticles in 98 g of deionized water, stir evenly and then heat. Slowly add 0.9 g of sodium alginate during the heating process. After complete dissolution, cool to room temperature to obtain an aluminum-sodium alginate mixture; then dissolve 1.9 g of chitosan and 2.5 g of anhydrous calcium chloride in 100 ml of 1 wt% acetic acid aqueous solution to obtain a chitosan-calcium chloride mixed solution; then slowly drop the aluminum-sodium alginate mixture into the chitosan-calcium chloride mixed solution, stand for 12 h, filter, wash, and freeze-dry to obtain an inclusion complex powder;

[0041] (4) Mix 130 g of polyurethane acrylate, 75 g of 1,6-hexanediol diacrylate, 40 g of dipropylene glycol diacrylate, 8 g of trimethylolpropane triacrylate, 5.5 g of modified monomer, 8 g of photoinitiator TPO-L, 8 g of dispersant BYK111, and 4 g of inclusion complex powder. Then magnetically stir the mixture at a speed of 600 rpm for 2 h and stand for 24 h to obtain a photosensitive resin premix solution;

[0042] (5) Ball mill 75 g of alumina powder, 13 g of zirconia, 5 g of chromium oxide, and 5 g of sintering aid at a rotation speed of 350 rpm for 10 h, and then grind through a 100-mesh sieve to obtain a ceramic powder;

[0043] (6) Premix the ceramic powder and the photosensitive resin premix solution through a homogenizer for high-speed mixing, and then use a vacuum degassing machine to degas and defoam the slurry for 15 min to obtain a photocurable alumina ceramic slurry with a solid content of 56 vol%. Among them, the rotation speed of the homogenizer is 2800 r / min, and the mixing time is 3 min.

[0044] Example 3: A photocurable alumina ceramic slurry, and the specific preparation steps are as follows:

[0045] (1) Disperse 2 g of chitosan nanofibers in 150 ml of ethanol solution, and ultrasonically treat until uniform. Then add 2 ml of silane coupling agent KH570, adjust the pH to 5, and stir at 70 °C for 5 h, centrifuge, wash, and dry to obtain vinylated chitosan nanofibers;

[0046] (2) Disperse 0.5 g of trimethylolpropane triacrylate and 0.5 g of vinylated chitosan nanofibers in deionized water, stir evenly, then add 0.05 g of ammonium persulfate and 0.03 g of TEMED, react at 30 °C for 2 h, wash twice with deionized water, freeze-dry, and crush to obtain a modified monomer;

[0047] (3) Disperse 6 g of aluminum nanoparticles in 100 g of deionized water, stir evenly and then heat. Slowly add 1 g of sodium alginate during the heating process. After complete dissolution, cool to room temperature to obtain an aluminum-sodium alginate mixture; then dissolve 2 g of chitosan and 3 g of anhydrous calcium chloride in 100 ml of 1 wt% acetic acid aqueous solution to obtain a chitosan-calcium chloride mixed solution; then slowly drop the aluminum-sodium alginate mixture into the chitosan-calcium chloride mixed solution, stand for 12 h, filter, wash, and freeze-dry to obtain an inclusion complex powder;

[0048] (4) Mix 150 g of polyurethane acrylate, 90 g of 1,6-hexanediol diacrylate, 45 g of dipropylene glycol diacrylate, 10 g of trimethylolpropane triacrylate, 6 g of modified monomer, 9 g of photoinitiator TPO-L, 10 g of dispersant BYK111, and 5 g of inclusion complex powder, and then magnetically stir the mixture at a speed of 600 rpm for 2 h and stand for 24 h to obtain a photosensitive resin premix solution;

[0049] (5) Ball-mill 80 g of alumina powder, 15 g of zirconia, 5 g of chromium oxide, and 5 g of sintering aid at a rotation speed of 300 - 400 rpm for 10 h, and then grind through a 100-mesh sieve to obtain a ceramic powder;

[0050] (6) Premix the ceramic powder and the photosensitive resin premix solution through a homogenizer for high-speed mixing, and then use a vacuum defoaming machine to degas and defoam the slurry for 15 min to obtain a photocurable alumina ceramic slurry with a solid content of 58 vol%, wherein the rotation speed of the homogenizer is 3000 r / min and the mixing time is 3 min.

[0051] Comparative Example 1: A photocurable alumina ceramic slurry, which is different from Example 2 in that the aluminum nanoparticles are not encapsulated. The specific preparation steps are as follows:

[0052] (1) Disperse 1.5 g of chitosan nanofibers in 130 ml of ethanol solution, and ultrasonically treat until uniform. Then add 1.5 ml of silane coupling agent KH570, adjust the pH to 4.4, and stir at 65 °C for 5 h. Centrifuge, wash, and dry to obtain vinylated chitosan nanofibers;

[0053] (2) Disperse 0.4 g of trimethylolpropane triacrylate and 0.4 g of vinylated chitosan nanofibers in deionized water, stir evenly, then add 0.05 g of ammonium persulfate and 0.03 g of TEMED, react at 30 °C for 2 h, wash twice with deionized water, freeze-dry, and crush to obtain a modified monomer;

[0054] (3) Mix 130 g of polyurethane acrylate, 75 g of 1,6-hexanediol diacrylate, 40 g of dipropylene glycol diacrylate, 8 g of trimethylolpropane triacrylate, 5.5 g of modified monomer, 8 g of photoinitiator TPO-L, 8 g of dispersant BYK111, and 4 g of aluminum nanoparticles, and then magnetically stir the mixture at a speed of 600 rpm for 2 h and let it stand for 24 h to obtain a photosensitive resin premix solution;

[0055] (4) Ball mill 75 g of alumina powder, 13 g of zirconia, 5 g of chromium oxide, and 5 g of sintering aid at a rotation speed of 350 rpm for 10 h, and then grind through a 100-mesh sieve to obtain a ceramic powder;

[0056] (5) Premix the ceramic powder and the photosensitive resin premix solution through a homogenizer for high-speed mixing, and then use a vacuum defoaming machine to degas and defoam the slurry for 15 min to obtain a photocurable alumina ceramic slurry with a solid content of 56 vol%, wherein the rotation speed of the homogenizer is 2800 r / min and the mixing time is 3 min.

[0057] Comparative Example 2: A photocurable alumina ceramic slurry, which is different from Example 2 in that chitosan nanofibers are directly added. The specific preparation steps are as follows:

[0058] (1) Disperse 5.5 g of aluminum nanoparticles in 98 g of deionized water, stir evenly and then heat. Slowly add 0.9 g of sodium alginate during the heating process. After complete dissolution, cool to room temperature to obtain an aluminum-sodium alginate mixture; Subsequently, dissolve 1.9 g of chitosan and 2.5 g of anhydrous calcium chloride in 100 ml of 1 wt% acetic acid aqueous solution to obtain a chitosan-calcium chloride mixed solution; Then, dropwise add the aluminum-sodium alginate mixture into the chitosan-calcium chloride mixed solution, let it stand for 12 h, filter, wash, and freeze-dry to obtain the inclusion complex powder;

[0059] (2) Mix 130 g of polyurethane acrylate, 75 g of 1,6 - hexanediol diacrylate, 40 g of dipropylene glycol diacrylate, 8 g of trimethylolpropane triacrylate, 5.5 g of chitosan nanofibers, 8 g of photoinitiator TPO - L, 8 g of dispersant BYK111, and 4 g of inclusion complex powder. Subsequently, magnetically stir the mixture at a speed of 600 rpm for 2 h and let it stand for 24 h to obtain a photosensitive resin premix;

[0060] (3) Ball - mill 75 g of alumina powder, 13 g of zirconia, 5 g of chromium oxide, and 5 g of sintering aid at a rotation speed of 350 rpm for 10 h, and then grind through a 100 - mesh sieve to obtain ceramic powder;

[0061] (4) Mix the ceramic powder and the photosensitive resin premix through a high - speed mixer. Subsequently, use a vacuum defoaming machine to degas and defoam the slurry for 15 min to obtain a photocurable alumina ceramic slurry with a solid content of 56 vol%. Among them, the rotation speed of the high - speed mixer is 2800 r / min and the mixing time is 3 min.

[0062] Comparative Example 3: A photocurable alumina ceramic slurry, which is different from Example 2 in that no chitosan nanofibers are added. The specific preparation steps are as follows:

[0063] (1) Disperse 5.5 g of aluminum nanoparticles in 98 g of deionized water, stir evenly and then heat. Slowly add 0.9 g of sodium alginate during the heating process. After complete dissolution, cool to room temperature to obtain an aluminum-sodium alginate mixture; Subsequently, dissolve 1.9 g of chitosan and 2.5 g of anhydrous calcium chloride in 100 ml of 1 wt% acetic acid aqueous solution to obtain a chitosan-calcium chloride mixed solution; Then, dropwise add the aluminum-sodium alginate mixture into the chitosan-calcium chloride mixed solution, let it stand for 12 h, filter, wash, and freeze-dry to obtain the inclusion complex powder;

[0064] (2) Mix 130 g of polyurethane acrylate, 75 g of 1,6 - hexanediol diacrylate, 40 g of dipropylene glycol diacrylate, 8 g of trimethylolpropane triacrylate, 8 g of photoinitiator TPO - L, 8 g of dispersant BYK111, and 4 g of inclusion complex powder. Subsequently, magnetically stir the mixture at a speed of 600 rpm for 2 h, and let it stand for 24 h to obtain a photosensitive resin premix.

[0065] (3) Ball - mill 75 g of alumina powder, 13 g of zirconia, 5 g of chromium oxide, and 5 g of sintering aid at a rotation speed of 350 rpm for 10 h, and then grind through a 100 - mesh sieve to obtain ceramic powder.

[0066] (4) Mix the ceramic powder and the photosensitive resin premix through a high - speed mixer. Subsequently, use a vacuum degassing machine to degas and defoam the slurry for 15 min to obtain a photocurable alumina ceramic slurry with a solid content of 56 vol%. Among them, the rotation speed of the homogenizer is 2800 r / min, and the mixing time is 3 min.

[0067] Comparative Example 4: A photocurable alumina ceramic slurry, which is different from Example 2 in that in step (2), trimethylolpropane triacrylate is replaced by an equimolar amount of 1,6 - hexanediol diacrylate. The specific preparation steps are as follows:

[0068] (1) Disperse 1.5 g of chitosan nanofibers in 130 ml of ethanol solution, and ultrasonically treat until uniform. Then add 1.5 ml of silane coupling agent KH570, adjust the pH to 4.4, and stir at 65 °C for 5 h, centrifuge, wash, and dry to obtain vinylated chitosan nanofibers.

[0069] (2) Disperse 0.31 g of 1,6 - hexanediol diacrylate and 0.4 g of vinylated chitosan nanofibers in deionized water, stir evenly, then add 0.05 g of ammonium persulfate and 0.03 g of TEMED, react at 30 °C for 2 h, wash twice with deionized water, freeze - dry, and crush to obtain a modified monomer.

[0070] (3) Disperse 5.5 g of aluminum nanoparticles in 98 g of deionized water, stir evenly and then heat. Slowly add 0.9 g of sodium alginate during the heating process. After complete dissolution, cool to room temperature to obtain an aluminum - sodium alginate mixture. Subsequently, dissolve 1.9 g of chitosan and 2.5 g of anhydrous calcium chloride in 100 ml of 1 wt% acetic acid aqueous solution to obtain a chitosan - calcium chloride mixed solution. Then, drop - wise add the aluminum - sodium alginate mixture into the chitosan - calcium chloride mixed solution, let it stand for 12 h, filter, wash, and freeze - dry to obtain inclusion complex powder.

[0071] (4) Mix 130 g of polyurethane acrylate, 75 g of 1,6 - hexanediol diacrylate, 40 g of dipropylene glycol diacrylate, 8 g of trimethylolpropane triacrylate, 5.5 g of modified monomer, 8 g of photoinitiator TPO - L, 8 g of dispersant BYK111, and 4 g of inclusion complex powder. Subsequently, magnetically stir the mixture at a speed of 600 rpm for 2 h and let it stand for 24 h to obtain a photosensitive resin premix.

[0072] (5) Ball - mill 75 g of alumina powder, 13 g of zirconia, 5 g of chromium oxide, and 5 g of sintering aid at a rotation speed of 350 rpm for 10 h, and then grind them through a 100 - mesh sieve to obtain ceramic powder.

[0073] (6) Mix the ceramic powder and the photosensitive resin premix at high speed through a homogenizer. Subsequently, use a vacuum defoaming machine to degas and defoam the slurry for 15 min to obtain a photocurable alumina ceramic slurry with a solid content of 56 vol%. Among them, the rotation speed of the homogenizer is 2800 r / min, and the mixing time is 3 min.

[0074] Performance testing

[0075] Slurry viscosity: Use a THS - NDJ - 5S type constant - temperature viscometer to test the sample slurry; the test results are shown in Table 1.

[0076] Carry out photocuring printing on the obtained ceramic slurry. Among them, the scanning speed is 1500 - 8000 mm / s, the spot diameter is 47 μm, the laser power is 230 - 860 mW, and the printing layer thickness is 20 - 150 μm to obtain a wet ceramic core. Subsequently, put the wet ceramic core into a low - temperature box - type resistance furnace for debinding. In an air atmosphere, first heat it at a rate of 2 °C / min to 375 °C and hold for 30 min. Then heat it at a rate of 2 °C / min to 485 °C and hold for 30 min. Then heat it at a rate of 10 °C / min to 600 °C and hold for 30 min. Continue to heat it at a heating rate of 5 °C / min to 1000 °C and hold for 2 h and then cool it with the furnace. Then place it in a high - temperature box - type resistance furnace and heat it at a rate of 10 °C / min to 1500 - 1600 °C and hold for 1 - 2 h and then cool it with the furnace to obtain a ceramic core; and conduct performance testing on the ceramic core:

[0077] Open porosity: Test the ceramic core according to the Archimedes drainage method;

[0078] Shrinkage rate: Test the shrinkage rate (Z - axis direction) of the ceramic core according to HB5353.2 - 2004. The test bar model is a cuboid of 55 mm×10 mm×4 mm;

[0079] Flexural strength: According to HB5353.3.2004, the three-point bending method was used to test the flexural strength of the ceramic core. A WDW-GD microcomputer-controlled electronic universal testing machine was used for the test. The test bar was a cuboid with dimensions of 100mm×10mm×4.5mm.

[0080] Table 1 Performance test results

[0081]

[0082] Data analysis: From the examples and comparative examples in Table 1, it can be seen that in the present invention, chitosan nanofibers are introduced into the premix by grafting and aluminum nanoparticles are added to the premix by inclusion. The chitosan-included aluminum nanoparticles are uniformly dispersed in the slurry, reducing particle agglomeration, lowering the viscosity of the slurry, and improving fluidity. The chitosan nanofibers form a three-dimensional network structure in the slurry by grafting, further improving the dispersion of the particles and enhancing the stability of the slurry. The combined action of the two not only reduces the viscosity of the slurry but also improves its rheological properties, making the slurry easier to process and form. At the same time, during the subsequent sintering process, on the one hand, the two can form a stable alumina phase, promoting the densification of the ceramic matrix. On the other hand, the temporary skeleton effect of the chitosan nanofibers limits the excessive movement of the particles, jointly optimizing the flexural strength, shrinkage rate, and open porosity of the ceramic core.

[0083] From Example 2 and Comparative Example 1, it can be seen that after the aluminum nanoparticles are included by chitosan, the interaction force between the particles is reduced, the viscosity of the slurry is lowered, and during the subsequent printing and sintering processes, the aluminum nanoparticles can generate a stable physical reinforcement phase at high temperatures, thereby enhancing the flexural strength of the core. At the same time, more physical reinforcement phases inhibit the volume change of the ceramic matrix, further reducing the shrinkage rate. Moreover, inclusion can make the aluminum nanoparticles more uniformly distributed in the slurry, promoting the densification of ceramic particles during the sintering process, further reducing the formation of pores, and it can cooperate with chitosan nanofibers.

[0084] It can be seen from Example 2 and Comparative Examples 2 and 3 that adding chitosan nanofibers by grafting significantly improves the viscosity of the slurry, the flexural strength, shrinkage rate, and open porosity of the core. This is mainly because the surface activity of chitosan nanofibers themselves can improve the compatibility between particles and resin, further reducing the viscosity. Grafting it onto trimethylolpropane triacrylate enables it to be uniformly dispersed in the slurry, effectively reducing the frictional resistance between ceramic particles, thereby reducing the overall viscosity of the slurry. At the same time, chitosan nanofibers can fill the gaps between ceramic particles, reducing the porosity in the slurry, thus reducing the open porosity of the sintered ceramic core. Moreover, it can play the role of a temporary skeleton during the sintering process, restricting the excessive movement and densification of ceramic particles, thereby reducing the sintering shrinkage rate.

[0085] It can be seen from Example 2 and Comparative Example 4 that by grafting chitosan nanofiber segments onto trimethylolpropane triacrylate, compared with grafting onto 1,6 - hexanediol diacrylate, although the viscosity of the ceramic slurry decreases to a certain extent, the flexural strength, shrinkage rate, and open porosity of the core obtained after printing and sintering are all significantly improved.

[0086] Those of ordinary skill in the art should understand that: the discussion of any above - mentioned embodiment is only exemplary and is not intended to imply that the scope of the present invention is limited to these examples; under the concept of the present invention, the technical features in the above - mentioned embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A method for preparing a light-cured alumina ceramic slurry, characterized in that: The following steps are involved: S1: Disperse chitosan nanofibers in an ethanol solution, homogenize by ultrasonication, then add silane coupling agent KH570, adjust the pH to 4-5, stir at 60-70°C for 4-5h, purify, and obtain olefinated chitosan nanofibers; S2: dispersing trimethylolpropane triacrylate and olefinated chitosan nanofibers in deionized water, stirring evenly, then adding ammonium persulfate and TEMED, reacting at 25-30°C for 1-2h, washing, freeze-drying, and crushing to obtain a modified monomer; S3: dispersing aluminum nanoparticles in deionized water, and then adding sodium alginate to obtain an aluminum-sodium alginate mixed solution; then dissolving chitosan and anhydrous calcium chloride in a 1wt% acetic acid aqueous solution to obtain a chitosan-calcium chloride mixed solution; then adding the aluminum-sodium alginate mixed solution dropwise to the chitosan-calcium chloride mixed solution, standing, and purifying to obtain inclusion compound powder; S4: polyurethane acrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, trimethylolpropane triacrylate, modified monomer, photoinitiator TPO-L, dispersant BYK111, inclusion compound powder are mixed, magnetically stirred, and allowed to stand to obtain a photosensitive resin premix solution; S5: ball-milling alumina powder, zirconium oxide, chromium oxide and a sintering aid, and sieving to obtain ceramic powder; S6: mixing the ceramic powder and the photosensitive resin premix, and then degassing and degassing the slurry to obtain a light-cured alumina ceramic slurry; In step S1, the amount ratio of chitosan nanofiber, ethanol solution and silane coupling agent KH570 is 1-2g:100-150ml:1-2ml; In step S2, the usage ratio of trimethylolpropane triacrylate, olefinated chitosan nanofibers, ammonium persulfate, and TEMED is 0.3-0.5 g: 0.3-0.5 g: 0.04-0.05 g: 0.02-0.03 g; The dosage ratio of the aluminum nanoparticles, deionized water, sodium alginate, chitosan, anhydrous calcium chloride, and acetic acid aqueous solution in step S3 is 5-6 g: 95-100 g: 0.8-1 g: 1.5-2 g: 2-3 g: 100 ml; In step S4, the usage ratio of polyurethane acrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, trimethylolpropane triacrylate, modified monomer, initiator TPO-L, dispersant BYK111, and inclusion compound powder is 100-150g: 60-90g: 30-45g: 5-10g: 5-6g: 6-9g: 6-10g: 3-5g.

2. The method for preparing the light-cured alumina ceramic slurry according to claim 1, characterized in that: The chitosan nanofibers in step S1 have a diameter of 30-50 nm and a length of 2 μm.

3. The method for preparing the light-cured alumina ceramic slurry according to claim 1, characterized in that: The particle size of the aluminum nanoparticles in step S3 is 50-100 nm.

4. The method for preparing the light-cured alumina ceramic slurry according to claim 1, characterized in that: The concentration of the acetic acid aqueous solution in step S3 is 1 wt %.

5. The method for preparing the light-cured alumina ceramic slurry according to claim 1, characterized in that: The dosage ratio of the alumina powder, zirconium oxide, chromium oxide and sintering aid in step S5 is 70-80g:10-15g:5g:5g.

6. The method for preparing the light-cured alumina ceramic slurry according to claim 1, characterized in that: The sintering aid in step S5 is a mixture of yttrium oxide, samarium oxide and lanthanum oxide in a weight ratio of 3:1:

1.

7. The method for preparing the light-cured alumina ceramic slurry according to claim 1, characterized in that: The ball milling speed in step S5 is 300-400 rpm and the time is 10 hours.

8. The method for preparing the light-cured alumina ceramic slurry according to claim 1, characterized in that: The solid content of the photocured alumina ceramic slurry in step S6 is 55-58 vol%.

9. The method for preparing the light-cured alumina ceramic slurry according to claim 1, characterized in that: The mixing in step S6 is performed by a homogenizer, the speed of the homogenizer is 2500-3000 r / min, and the mixing time is 3 min.

10. A photocured alumina ceramic slurry, characterized in that: The photocured alumina ceramic slurry is prepared according to the preparation method of any one of claims 1 to 9.

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