A method for modifying ceramic powder based on light-cured forming and the product and application thereof

Abstract

The application belongs to the technical field of ceramic additive manufacturing, and particularly relates to a ceramic powder modification method based on light-curing forming, a product obtained by the method and application. The application performs modification treatment on silicon nitride ceramic particles in advance, so that the silicon nitride ceramic particles are more easily dispersed in photosensitive resin, the stability of light-curing slurry is improved, the light-curing depth of the slurry is improved, and the viscosity of the slurry is reduced. In the ceramic slurry provided by the application, active diluents with different functional groups are used to realize performance complementation, so that the prepared ceramic light-curing slurry can realize a larger curing depth under a smaller laser power. The light-curing ceramic slurry can be used to prepare porous silicon nitride ceramics after 3D printing, debinding and sintering. The prepared silicon nitride ceramics have high porosity and high bending strength, and have superior performance.

Description

Technical Field

[0001] This invention belongs to the field of ceramic additive manufacturing technology, specifically relating to a method for modifying ceramic powder based on photopolymerization molding, the resulting product, and its applications. Background Technology

[0002] With its advantages such as high temperature resistance, corrosion resistance, high strength, and good biocompatibility, Si3N4 ceramics have shone brightly in aerospace, biomedical, and military fields. As the applications of Si3N4 ceramics continue to expand, higher demands are being placed on them. However, the high hardness and strength of Si3N4 ceramics make it difficult to prepare Si3N4 ceramics with complex structures using traditional manufacturing methods. Therefore, the application of Si3N4 ceramics in the high-end market is limited. To solve the problem of complex forming of Si3N4 ceramics, it is necessary to find new technologies capable of manufacturing ceramics with complex shapes.

[0003] Unlike traditional turning and milling methods, 3D printing creates parts by layering materials. Part design is achieved through computer-generated 3D models, which are then sliced ​​layer by layer by the computer. This allows for the fabrication of complex and intricate parts with a short development cycle, saving time and costs. During printing, the machine prints layer by layer according to the sliced ​​data, creating a 3D product. Photopolymer 3D printing is one method of 3D printing, typically involving mixing ceramic particles with photosensitive resin to form a slurry or an organic ceramic precursor. The photosensitive resin is then cured by cross-linking polymerization caused by irradiation with light of a specific wavelength. The high absorbance and refractive index of silicon nitride ceramic particles result in a lower curing depth for silicon nitride photopolymer slurries under the same laser power irradiation compared to white oxide ceramic slurries such as Al2O3 and ZrO2. To ensure sufficient curing depth during printing, higher laser power is usually required; however, excessively high laser power can lead to wrinkles and over-curing in the printed layers. Therefore, improving the curing depth of silicon nitride photopolymer slurries is a crucial problem to be solved in the development of silicon nitride photopolymer printing. Summary of the Invention

[0004] To address the issues of high light absorption and extremely high viscosity in existing silicon nitride photocurable ceramic slurries, this invention provides a method for modifying ceramic powders based on photocuring molding.

[0005] The present invention also provides silicon nitride ceramic powder obtained by the above preparation method.

[0006] Another object of the present invention is to provide the application of the above-mentioned modified ceramic powder in the preparation of 3D printing photocurable slurry.

[0007] The specific technical solution of the present invention is as follows: This invention provides a method for modifying ceramic powder, comprising the following steps: (1) The ceramic powder is pre-treated with surface oxidation to obtain oxidized ceramic powder; (2) The oxidized ceramic powder was ball-milled and mixed with silane coupling agent for modification, and then sintering aid and dispersant were added and ball-milled again to obtain a mixed slurry; (3) Adjust the pH value of the mixed slurry, and then continue to ball mill and disperse it. Filter and dry the uniformly dispersed solution to obtain the modified ceramic powder. The ceramic powder is silicon nitride powder or silicon carbide powder.

[0008] Furthermore, in step (1), the surface oxidation treatment is carried out at 1100-1300 °C. o Oxidize at temperature C for 0.5-2 hours.

[0009] Furthermore, in step (2), the amount of silane coupling agent added is 0.5-2 wt% of the oxidized ceramic powder; the silane coupling agent is one or more of KH-560, KH-550, and SA; the mixing modification is ball milling and dispersion in hexanol solution for 4-8 h; the volume ratio of the oxidized ceramic powder to the ethanol solution is 1:1-1:2.

[0010] Further, in step (2), the amount of sintering aid added accounts for 2-10 wt% of the oxidized ceramic powder; the sintering aid is composed of Y2O3 and Al2O3 in a mass ratio of 1-3:2-5; the amount of dispersant added accounts for 0.4-1.5 wt% of the oxidized ceramic powder; the dispersant is one or more of KSO2000, KSO163, DW-404, Solsperse 41000 and K2001; the ball milling time is 1-4 h.

[0011] Furthermore, in step (3), the pH value of the mixed slurry is adjusted to 10-13 using 25 wt% TMAH; the ball milling dispersion time is 2-5 h.

[0012] The present invention also provides an application of the modified ceramic powder prepared by the above modification method in the preparation of 3D printing photocurable ceramic slurry, characterized in that the proportions of each raw material in the photocurable ceramic slurry are as follows: 40-65 wt% modified ceramic powder, 28-58.6 wt% photosensitive resin, 0.3-1.5 wt% dispersant, 0.5-2.5 wt% plasticizer, and 0.6-3 wt% photoinitiator.

[0013] Furthermore, the modified ceramic powder is modified silicon nitride powder or a mixture of modified silicon nitride powder and silicon carbide powder; when the ceramic powder is a mixture, the mass ratio of the modified silicon nitride powder to the silicon carbide powder is 8:3.

[0014] Furthermore, the photosensitive resin comprises pentaerythritol tetraacrylate ethoxylate, o-phenylphenethyl acrylate, and a bifunctional monomer; the bifunctional monomer is 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, polyethylene glycol (200) diacrylate, polyethylene glycol (400) diacrylate, polyethylene glycol (600) diacrylate, neopentyl glycol diacrylate propylene oxide, or tricyclodecanedimethyl diacrylate; in the photosensitive resin: the proportion of the bifunctional monomer is 0-40 wt%; the proportion of pentaerythritol tetraacrylate ethoxylate is 17.14-57.14 wt%; the proportion of o-phenylphenethyl acrylate is 25.7-71.42 wt%; the photoinitiator is (2,4... The dispersant is any one or more of (6-trimethylbenzoyl)diphenylphosphine oxide, chlorobenzaldehyde, p-isopropylbenzylthiophenol, and ethyl acrylate; the dispersant is any one or two of KSO2000, KSO163, DW-404, and K2201; and the plasticizer is polyethylene glycol.

[0015] Furthermore, when using photocurable ceramic slurry for 3D printing, the process includes model slicing, curing depth testing, printing, debinding, and sintering.

[0016] Furthermore, the degreasing program is set as follows: 0-360℃ at a rate of 0.1-0.5℃ / min, holding for 1-2 hours; 360-440℃ at a rate of 0.1-0.5℃ / min, holding for 2-4 hours; 440-480℃ at a rate of 0.1-0.5℃ / min, holding for 1-2 hours; 480-650℃ at a rate of 0.1-0.5℃ / min, holding for 1-2 hours; 650-20℃ at a rate of 1-5℃ / min. The sintering process is set as follows: 0-600℃ at a rate of 1-8℃ / min, holding for 1-2 hours; 600-1750℃ at a rate of 1-5℃ / min, holding for 1-3 hours; 1750-600℃ at a rate of 1-10℃ / min; 600-20℃ at a rate of 5-20℃ / min.

[0017] The preparation process of the 3D printing photocurable ceramic slurry provided by the present invention is as follows: ceramic powder, photosensitive resin, photoinitiator, dispersant and plasticizer are taken by mass percentage, stirred in a ball mill, and defoamed to obtain photocurable slurry.

[0018] The specific printing process of the 3D printing photocurable ceramic slurry provided by this invention is as follows: (1) Place the photocurable ceramic slurry in a photocurable 3D printing device and print the blank by laser curing; (2) The printed blank is placed in a degreasing furnace for degreasing, and heated at a rate of 0.1-0.5℃ / min and kept at 360℃, 440℃, 480℃ and 650℃ for 1-2 hours.

[0019] (3) The degreased green body is sintered in a nitrogen atmosphere at a heating rate of 1-8℃ / min and held at 600℃ and 1750℃ for 1-3h. After cooling, silicon nitride ceramic samples are obtained.

[0020] The submicron-sized silicon nitride ceramic powder and silicon carbide ceramic powder used in this invention have a particle size of 0.5-5 μm.

[0021] Compared with the prior art, the present invention has the following beneficial effects: 1. The ceramic slurry provided by the present invention uses active diluents with different functional groups to achieve complementary performance, so that the prepared ceramic photocurable slurry can achieve a large curing depth at a relatively small laser power; 2. The photocurable ceramic slurry of the present invention can be used to prepare porous silicon nitride ceramics after 3D printing, debinding and sintering. The prepared silicon nitride ceramics have high porosity, high flexural strength and excellent performance. 3. The present invention pre-modifies the silicon nitride ceramic particles, making them easier to disperse in the photosensitive resin, thereby improving the stability of the photocurable slurry, increasing the photocuring depth of the slurry, and reducing the viscosity of the slurry. Attached Figure Description

[0022] Figure 1 The debinding and sintering curve of Example 1; Figure 2 The graph shows the flexural strength test results of the materials prepared in Examples 1-4; Figure 3 Photocuring depth test curves for the materials prepared in Examples 1-4; Figure 4 The graph shows the flexural strength test results of the materials prepared in Examples 5-6; Figure 5 The photocuring depth test curves for the materials prepared in Examples 5-6; Figure 6 The debinding and sintering curve is shown in Comparative Example 1; Figure 7 This is a comparison diagram of the samples prepared in Example 1 and Comparative Example 1. Detailed Implementation

[0023] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0024] In some embodiments, the particle size of the silicon nitride ceramic powder or silicon carbide powder used in this invention is 0.5-1 μm.

[0025] In some embodiments, when using a single silicon nitride powder, the most preferred method is to use 1 μm silicon nitride ceramic powder and 0.5 μm silicon nitride powder in a mass ratio of 1:1.

[0026] Example 1 The composition of the photocurable ceramic slurry in this embodiment, by weight percentage, is as follows: Silicon nitride ceramic powder (1μm) 27.5wt%, silicon nitride ceramic powder (0.5μm) 27.5wt%, pentaerythritol tetraacrylate ethoxylate 25wt%, o-phenyl phenylethyl acrylate 18wt%, photoinitiator 0.8wt%, plasticizer 0.5wt%, dispersant 0.7wt%.

[0027] The specific preparation process is as follows: S0, weigh out 50wt% of silicon nitride ceramic powder (1μm) and 50wt% of silicon nitride ceramic powder (0.5μm), and heat the ceramic powders in a muffle furnace at 1200 degrees for 1 hour. S1. Pour the treated ceramic powder and ethanol into a ball mill jar at a volume ratio of 1:2. Add 1.5 wt% KH-560 (silane coupling agent) ceramic powder and ball mill for 4 hours. Then add 2 wt% Y2O3 (sintering aid), 3 wt% Al2O3 (sintering aid), and 0.45 wt% K2201 (dispersant). Ball mill for 2 hours. Adjust the pH to 11 using TMAH and dry. S2, take 55wt% ceramic powder, 25wt% pentaerythritol tetraacrylate ethoxylate, 18wt% o-phenylphenylethyl acrylate, 0.8wt% TPO (photoinitiator), 0.7wt% K2201 (dispersant), and 0.5wt% PEG-300 (plasticizer), respectively, and ball mill and stir for 2 hours at a mass ratio of 1:2 between the mixed slurry and ceramic balls. After defoaming treatment, a photocurable slurry is obtained.

[0028] The application steps for this ceramic slurry are as follows: Model slices were prepared; in this embodiment, the slice layer thickness was 20 μm. A trial curing test was performed to determine the printing power, followed by printing. After printing, debinding and sintering were carried out (the debinding and sintering curve is shown in the figure). Figure 1 As shown in the image.

[0029] The defatting program is set as follows: 0-360℃, heat up at a rate of 0.5℃ / min, hold for 1 hour; 360-440℃, heat up at a rate of 0.2℃ / min, hold for 2 hours; 440-480℃, heat up at a rate of 0.1℃ / min, hold for 1 hour; 480-650℃, heat up at a rate of 0.1℃ / min, hold for 2 hours; 650-20℃, cool down at a rate of 5℃ / min.

[0030] The sintering program is set as follows: 0-600℃, heating at a rate of 5℃ / min, holding for 1 hour; 600-1750℃, heating at a rate of 2℃ / min, holding for 3 hours; 1750-600℃, cooling at a rate of 5℃ / min; 600-20℃, cooling at a rate of 10℃ / min.

[0031] In this embodiment, the laser power and curing depth of the ceramic slurry are as follows: Figure 3 As shown. The results of the flexural strength test are as follows. Figure 2 As shown, the flexural strength of Si3N4 ceramic was tested using a CM5105 universal testing machine through a three-point bending test. Sintered Si3N4 ceramic was cut into strips with dimensions of 36mm × 4mm × 3mm (l × b × h). The span during measurement was 30mm (L), the loading speed was 0.5mm / min, and the maximum external load (P) was recorded after the sample fractured. Based on the data, the flexural strength was calculated to be 235MPa. Example 2 The composition of the photocurable ceramic slurry in this embodiment, by weight percentage, is as follows: 40wt% silicon nitride ceramic powder (1μm), 15wt% silicon carbide ceramic powder (1μm), 25wt% pentaerythritol tetraacrylate ethoxylate, 18wt% o-phenyl phenylethyl acrylate, 0.8wt% photoinitiator, 0.5wt% plasticizer, and 0.7wt% dispersant.

[0032] The specific preparation process is as follows: S0, weigh silicon nitride ceramic powder (1μm) and silicon carbide ceramic powder (1μm) in a ratio of 8:3 respectively, and heat the ceramic powder in a muffle furnace at 1200 degrees for 2 hours; S1. The treated ceramic powder and ethanol were poured into a ball mill jar at a volume ratio of 1:2. 1.5 wt% KH-560 (silane coupling agent) ceramic powder was added and ball milled for 4 hours. Then, 2 wt% Y2O3 (sintering aid), 3 wt% Al2O3 (sintering aid), and 0.45 wt% K2201 (dispersant) ceramic powder were added and ball milled for 2 hours. The pH was adjusted to 12 using TMAH and then dried. S2, take 55wt% ceramic powder, 25wt% pentaerythritol tetraacrylate ethoxylate, 18wt% o-phenylphenylethyl acrylate, 0.8wt% TPO (photoinitiator), 0.7wt% K2201 (dispersant), and 0.5wt% PEG-300 (plasticizer), respectively, and ball mill and stir for 2 hours at a mass ratio of 1:2 between the mixed slurry and ceramic balls. After defoaming treatment, a photocurable slurry is obtained.

[0033] The application steps for this ceramic slurry are as follows: Model slices are prepared, with a slice thickness of 20 μm in this embodiment; a trial curing is performed to determine the printing power, followed by printing. After printing is complete, degreasing and sintering are then performed.

[0034] The defatting program is set as follows: 0-360℃, heat up at a rate of 0.5℃ / min, hold for 1 hour; 360-440℃, heat up at a rate of 0.2℃ / min, hold for 2 hours; 440-480℃, heat up at a rate of 0.1℃ / min, hold for 1 hour; 480-650℃, heat up at a rate of 0.1℃ / min, hold for 2 hours; 650-20℃, cool down at a rate of 5℃ / min.

[0035] The sintering program is set as follows: 0-600℃, heating at a rate of 5℃ / min, holding for 1 hour; 600-1750℃, heating at a rate of 2℃ / min, holding for 3 hours; 1750-600℃, cooling at a rate of 5℃ / min; 600-20℃, cooling at a rate of 10℃ / min.

[0036] In this embodiment, the laser power and curing depth of the ceramic slurry are as follows: Figure 3 As shown. The results of the flexural strength test are as follows. Figure 2 As shown, the flexural strength of ceramics was tested using a CM5105 universal testing machine through a three-point bending test. The sintered ceramic was cut into strips with dimensions of 36mm × 4mm × 3mm (l × b × h). During measurement, the span was 30mm (L), the loading speed was 0.5mm / min, and the maximum external load (P) was recorded after the sample fractured. Based on the data, the flexural strength was calculated to be 256MPa.

[0037] Example 3 The composition of the photocurable ceramic slurry in this embodiment, by weight percentage, is as follows: Silicon nitride ceramic powder (1μm) 55wt%, pentaerythritol tetraacrylate ethoxylate 18wt%, o-phenyl phenylethyl acrylate 10wt%, bifunctional monomer 1,6-hexanediol diacrylate 10wt%, photoinitiator 0.8wt%, plasticizer 0.4wt%, dispersant 0.8wt%.

[0038] The specific preparation process is as follows: S0, weigh out silicon nitride ceramic powder (1μm). Place the ceramic powder in a muffle furnace and heat at 1200 degrees Celsius for 1 hour; S1, the ceramic powder and ethanol are poured into a ball mill jar at a volume ratio of 1:2, 1.5wt% KH-560 (silane coupling agent) is added, and the mixture is ball milled for 4 hours. Then, 2wt% Y2O3, 3wt% Al2O3 (sintering aid), and 0.45wt% KSO2000 (dispersant) are added and the mixture is ball milled for 2 hours. The pH is adjusted to 13 using TMAH and then dried. S2, take 55wt% ceramic powder, 18wt% pentaerythritol tetraacrylate ethoxylate, 10wt% o-phenylphenylethyl acrylate, 15wt% difunctional monomer 1,6-hexanediol diacrylate, 0.8wt% TPO (photoinitiator), 0.8wt% KSO2000 (dispersant), and 0.4wt% PEG-300 (plasticizer), respectively, and ball mill and stir for 2 hours at a mass ratio of 1:2 between the mixed slurry and ceramic balls. After defoaming treatment, a photocurable slurry is obtained.

[0039] The application steps for this ceramic slurry are as follows: Model slices are prepared, with a slice thickness of 20 μm in this embodiment; a trial curing is performed to determine the printing power, followed by printing. After printing is complete, degreasing and sintering are then performed.

[0040] The defatting program is set as follows: 0-360℃, heat up at a rate of 0.4℃ / min, hold for 1 hour; 360-440℃, heat up at a rate of 0.2℃ / min, hold for 2 hours; 440-480℃, heat up at a rate of 0.1℃ / min, hold for 1 hour; 480-650℃, heat up at a rate of 0.1℃ / min, hold for 2 hours; 650-20℃, cool down at a rate of 6℃ / min.

[0041] The sintering program is set as follows: 0-600℃ at a rate of 6℃ / min, hold for 1 hour; 600-1750℃ at a rate of 2℃ / min, hold for 3 hours; 1750-600℃ at a rate of 5℃ / min, cool down; 600-20℃ at a rate of 10℃ / min.

[0042] In this embodiment, the laser power and curing depth of the ceramic slurry are as follows: Figure 3 As shown. The results of the flexural strength test are as follows. Figure 2 As shown, the flexural strength of Si3N4 ceramic was tested using a CM5105 universal testing machine through a three-point bending test. Sintered Si3N4 ceramic was cut into strips with dimensions of 36mm × 4mm × 3mm (l × b × h). The span during measurement was 30mm (L), the loading speed was 0.5mm / min, and the maximum external load (P) was recorded after the sample fractured. Based on the data, the flexural strength was calculated to be 205MPa. Example 4 The composition of the photocurable ceramic slurry in this embodiment, by weight percentage, is as follows: The composition includes 55wt% silicon nitride ceramic powder (0.5μm), 18wt% pentaerythritol tetraacrylate ethoxylate, 10wt% o-phenyl phenylethyl acrylate, 15wt% difunctional monomer tripropylene glycol diacrylate, 0.7wt% photoinitiator, 0.4wt% plasticizer, and 0.9wt% dispersant.

[0043] The specific preparation process is as follows: S0, weigh out silicon nitride ceramic powder (0.5μm). Place the ceramic powder in a muffle furnace and heat at 1200 degrees Celsius for 2 hours; S1, the ceramic powder and ethanol are poured into a ball mill jar at a volume ratio of 1:2, 1.6 wt% KH-560 (silane coupling agent) is added, and the mixture is ball milled for 4 hours. Then, 2 wt% Y2O3, 3 wt% Al2O3 (sintering aid), and 0.45 wt% DW-404 (dispersant) are added and the mixture is ball milled for 2 hours. The pH is adjusted to 10 using TMAH and then dried. S2, take 55wt% ceramic powder, 18wt% pentaerythritol tetraacrylate ethoxylate, 10wt% o-phenylphenylethyl acrylate, 15wt% difunctional monomer tripropylene glycol diacrylate, 0.7wt% TPO (photoinitiator), 0.9wt% DW-404 (dispersant), and 0.4wt% PEG-300 (plasticizer), respectively, and ball mill and stir for 2 hours at a mass ratio of 1:2 between the mixed slurry and ceramic balls. After defoaming treatment, a photocurable slurry is obtained.

[0044] The application steps for this ceramic slurry are as follows: Model slices are prepared, with a slice thickness of 20 μm in this embodiment; a trial curing is performed to determine the printing power, followed by printing. After printing is complete, degreasing and sintering are then performed.

[0045] The defatting program is set as follows: 0-360℃, heat up at a rate of 0.2℃ / min, hold for 1 hour; 360-440℃, heat up at a rate of 0.1℃ / min, hold for 2 hours; 440-480℃, heat up at a rate of 0.1℃ / min, hold for 1 hour; 480-650℃, heat up at a rate of 0.1℃ / min, hold for 2 hours; 650-20℃, cool down at a rate of 5℃ / min.

[0046] The sintering program is set as follows: 0-600℃, heating at a rate of 3℃ / min, holding for 1 hour; 600-1750℃, heating at a rate of 2℃ / min, holding for 3 hours; 1750-600℃, cooling at a rate of 5℃ / min; 600-20℃, cooling at a rate of 10℃ / min.

[0047] In this embodiment, the laser power and curing depth of the ceramic slurry are as follows: Figure 3 As shown. The results of the flexural strength test are as follows. Figure 2 As shown, the flexural strength of Si3N4 ceramic was tested using a CM5105 universal testing machine through a three-point bending test. The sintered Si3N4 ceramic was cut into strips with dimensions of 36mm × 4mm × 3mm (l × b × h). During measurement, the span was 30mm (L), the loading speed was 0.5mm / min, and the maximum external load (P) was recorded after the sample fractured. Based on the data, the flexural strength was calculated to be 219MPa.

[0048] Example 5 The composition of the photocurable ceramic slurry in this embodiment, by weight percentage, is as follows: Silicon nitride ceramic powder (1μm) 55wt%, pentaerythritol tetraacrylate ethoxylate 25wt%, o-phenyl phenylethyl acrylate 18wt%, photoinitiator 0.8wt%, plasticizer 0.5wt%, dispersant 0.7wt%.

[0049] The specific preparation process is as follows: S0, weigh out silicon nitride ceramic powder (1μm) and heat it in a muffle furnace at 1200 degrees for 1 hour; S1. Pour the treated ceramic powder and ethanol into a ball mill jar at a volume ratio of 1:2. Add 1.5 wt% KH-560 (silane coupling agent) ceramic powder and ball mill for 4 hours. Then add 2 wt% Y2O3 (sintering aid), 3 wt% Al2O3 (sintering aid), and 0.45 wt% K2201 (dispersant) ceramic powder and ball mill for 2 hours. Adjust the pH to 11 using TMAH and dry. S2, take 55wt% ceramic powder, 25wt% pentaerythritol tetraacrylate ethoxylate, 18wt% o-phenylphenylethyl acrylate, 0.8wt% TPO (photoinitiator), 0.7wt% K2201 (dispersant), and 0.5wt% PEG-300 (plasticizer), respectively, and ball mill and stir for 2 hours at a mass ratio of 1:2 between the mixed slurry and ceramic balls. After defoaming treatment, a photocurable slurry is obtained.

[0050] The application steps for this ceramic slurry are as follows: The model is sliced, and the slice layer thickness in Comparative Example 1 is 20μm; the printing power is determined by trial curing, and then printing is carried out. After printing is completed, degreasing and sintering are performed.

[0051] The defatting program is set as follows: 0-360℃, heat up at a rate of 0.5℃ / min, hold for 1 hour; 360-440℃, heat up at a rate of 0.2℃ / min, hold for 2 hours; 440-480℃, heat up at a rate of 0.1℃ / min, hold for 1 hour; 480-650℃, heat up at a rate of 0.1℃ / min, hold for 2 hours; 650-20℃, cool down at a rate of 5℃ / min.

[0052] The sintering program is set as follows: 0-600℃, heating at a rate of 5℃ / min, holding for 1 hour; 600-1750℃, heating at a rate of 2℃ / min, holding for 3 hours; 1750-600℃, cooling at a rate of 5℃ / min; 600-20℃, cooling at a rate of 10℃ / min.

[0053] Example 5: Laser power and curing depth of ceramic slurry as follows Figure 4 As shown. The results of the flexural strength test are as follows. Figure 5 As shown, the flexural strength of Si3N4 ceramic was tested using a CM5105 universal testing machine through a three-point bending test. Sintered Si3N4 ceramic was cut into strips with dimensions of 36mm × 4mm × 3mm (l × b × h). The span during measurement was 30mm (L), the loading speed was 0.5mm / min, and the maximum external load (P) was recorded after the sample fractured. Based on the data, the flexural strength was calculated to be 198MPa. Example 6 The composition of the photocurable ceramic slurry in this embodiment, by weight percentage, is as follows: Silicon nitride ceramic powder (0.5μm) 55wt%, pentaerythritol tetraacrylate 25wt%, o-phenyl phenylethyl acrylate 18wt%, photoinitiator 0.7wt%, plasticizer 0.4wt%, dispersant 0.9wt%.

[0054] The specific preparation process is as follows: S0, weigh out silicon nitride ceramic powder (0.5μm). Place the ceramic powder in a muffle furnace and heat at 1200 degrees Celsius for 2 hours; S1, the ceramic powder and ethanol are poured into a ball mill jar at a volume ratio of 1:2, 1.6 wt% KH-560 (silane coupling agent) is added, and the mixture is ball milled for 4 hours. Then, 2 wt% Y2O3, 3 wt% Al2O3 (sintering aid), and 0.45 wt% DW-404 (dispersant) are added and the mixture is ball milled for 2 hours. The pH is adjusted to 10 using TMAH and then dried. S2, take 55wt% ceramic powder, 25wt% pentaerythritol tetraacrylate ethoxylate, 18wt% o-phenyl phenylethyl acrylate, 0.7wt% TPO (photoinitiator), 0.9wt% DW-404 (dispersant), and 0.4wt% PEG-300 (plasticizer), respectively, ball mill and stir, and defoam to obtain photocurable slurry.

[0055] The application steps for this ceramic slurry are as follows: Model slices are prepared, with a slice thickness of 20 μm in this embodiment; a trial curing is performed to determine the printing power, followed by printing. After printing is complete, degreasing and sintering are then performed.

[0056] The defatting program is set as follows: 0-360℃, heat up at a rate of 0.2℃ / min, hold for 1 hour; 360-440℃, heat up at a rate of 0.1℃ / min, hold for 2 hours; 440-480℃, heat up at a rate of 0.1℃ / min, hold for 1 hour; 480-650℃, heat up at a rate of 0.1℃ / min, hold for 2 hours; 650-20℃, cool down at a rate of 5℃ / min.

[0057] The sintering program is set as follows: 0-600℃, heating at a rate of 3℃ / min, holding for 1 hour; 600-1750℃, heating at a rate of 2℃ / min, holding for 3 hours; 1750-600℃, cooling at a rate of 5℃ / min; 600-20℃, cooling at a rate of 10℃ / min.

[0058] In this embodiment, the laser power and curing depth of the ceramic slurry are as follows: Figure 4 As shown. The results of the flexural strength test are as follows. Figure 5 As shown, the flexural strength of Si3N4 ceramic was tested using a CM5105 universal testing machine through a three-point bending test. The sintered Si3N4 ceramic was cut into strips with dimensions of 36mm × 4mm × 3mm (l × b × h). During measurement, the span was 30mm (L), the loading speed was 0.5mm / min, and the maximum external load (P) was recorded after the sample fractured. Based on the data, the flexural strength was calculated to be 206MPa.

[0059] Comparative Example 1 The composition of the light-cured ceramic slurry, by mass percentage, is the same as that in Example 1.

[0060] The specific preparation process is as follows: S0, weigh out 50wt% of silicon nitride ceramic powder (1μm) and 50wt% of silicon nitride ceramic powder (0.5μm). Place the ceramic powder in a muffle furnace and heat at 1200 degrees Celsius for 1 hour; S1, the ceramic powder and ethanol are poured into a ball mill jar at a volume ratio of 1:2, 1.5 wt% KH-560 (silane coupling agent) ceramic powder is added, and the mixture is ball milled for 4 hours. Then, 2 wt% Y2O3 (sintering aid), 3 wt% Al2O3 (sintering aid), and 0.45 wt% K2201 (dispersant) are added and the mixture is ball milled for 2 hours. The pH is adjusted to 11 using TMAH and then dried. S2, take 55wt% ceramic powder, 25wt% pentaerythritol tetraacrylate ethoxylate, 18wt% o-phenylphenylethyl acrylate, 0.8wt% TPO (photoinitiator), 0.7wt% K2201 (dispersant), and 0.5wt% PEG-300 (plasticizer), respectively, and ball mill and stir for 2 hours at a mass ratio of 1:2 between the mixed slurry and ceramic balls. After defoaming treatment, a photocurable slurry is obtained.

[0061] The application steps for this ceramic slurry are as follows: Model slices were prepared; in this embodiment, the slice layer thickness was 20 μm. A trial curing test was performed to determine the printing power, followed by printing. After printing, debinding and sintering were carried out (the debinding and sintering curve is shown in the figure). Figure 6 As shown in the image.

[0062] The defatting program is set as follows: 0-480℃, heat up at a rate of 0.5℃ / min, hold for 1 hour; 480-650℃, heat up at a rate of 0.2℃ / min, hold for 2 hours; 650-20℃, cool down at a rate of 5℃ / min.

[0063] The sintering program is set as follows: 0-600℃, heating at a rate of 5℃ / min, holding for 1 hour; 600-1750℃, heating at a rate of 2℃ / min, holding for 3 hours; 1750-600℃, cooling at a rate of 5℃ / min; 600-20℃, cooling at a rate of 10℃ / min.

[0064] Cracks appeared on the surface of the comparative example sample after sintering. (The sample appears to be...) Figure 7 As shown, further testing is not possible.

Claims

1. A method for modifying ceramic powder, characterized in that, Includes the following steps: (1) The ceramic powder is pre-treated with surface oxidation to obtain oxidized ceramic powder; (2) The oxidized ceramic powder was ball-milled and mixed with silane coupling agent for modification, and then sintering aid and dispersant were added and ball-milled again to obtain a mixed slurry; (3) Adjust the pH value of the mixed slurry, and then continue to ball mill and disperse it. Filter and dry the uniformly dispersed solution to obtain the modified ceramic powder. The ceramic powder is silicon nitride powder or silicon carbide powder.

2. The method for modifying ceramic powder according to claim 1, characterized in that, In step (1), the surface oxidation treatment is carried out at 1100-1300 °C. o Oxidize at temperature C for 0.5-2 hours.

3. The method for modifying ceramic powder according to any one of claims 1-2, characterized in that, In step (2), the amount of silane coupling agent added is 0.5-2 wt% of the oxidized ceramic powder; the silane coupling agent is one or more of KH-560, KH-550, and SA; the mixing modification is ball milling and dispersion in hexanol solution for 4-8 hours; the volume ratio of the oxidized ceramic powder to the ethanol solution is 1:1-1:

2.

4. The method for modifying ceramic powder according to claim 1 or 3, characterized in that, In step (2), the amount of sintering aid added accounts for 2-10 wt% of the oxidized ceramic powder; the sintering aid is composed of Y2O3 and Al2O3 in a mass ratio of 1-3:2-5; the amount of dispersant added accounts for 0.4-1.5 wt% of the oxidized ceramic powder; the dispersant is one or more of KSO2000, KSO163, DW-404, Solsperse 41000 and K2001; the ball milling time is 1-4 h.

5. The method for modifying ceramic powder according to any one of claims 1-4, characterized in that, In step (3), the pH value of the mixed slurry is adjusted to 10-13 using 25wt% TMAH; the ball milling dispersion time is 2-5h.

6. The application of a modified ceramic powder prepared by the modification method according to any one of claims 1-5 in the preparation of 3D printing photocurable ceramic slurry, characterized in that, The proportions of each raw material in the photocurable ceramic slurry are as follows: 40-65 wt% modified ceramic powder, 28-58.6 wt% photosensitive resin, 0.3-1.5 wt% dispersant, 0.5-2.5 wt% plasticizer, and 0.6-3 wt% photoinitiator.

7. The application of the modified ceramic powder prepared by the modification method according to claim 6 in the preparation of 3D printing photocurable ceramic slurry, characterized in that, The modified ceramic powder is modified silicon nitride powder or a mixture of modified silicon nitride powder and silicon carbide powder; when the ceramic powder is a mixture, the mass ratio of the modified silicon nitride powder to the silicon carbide powder is 8:

3.

8. The application of the modified ceramic powder according to claim 7 in the preparation of 3D printing photocurable ceramic slurry, characterized in that, The photosensitive resin comprises pentaerythritol tetraacrylate ethoxylate, o-phenylphenethyl acrylate, and a bifunctional monomer; the bifunctional monomer is 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, polyethylene glycol (200) diacrylate, polyethylene glycol (400) diacrylate, polyethylene glycol (600) diacrylate, neopentyl glycol diacrylate propylene oxide, or tricyclodecanedimethyl diacrylate; in the photosensitive resin: the proportion of the bifunctional monomer is 0-40 wt%; the proportion of pentaerythritol tetraacrylate ethoxylate is 17.14-57.14 wt%; the proportion of o-phenylphenethyl acrylate is 25.7-71.42 wt%; the photoinitiator is (2,4... The dispersant is any one or more of (6-trimethylbenzoyl)diphenylphosphine oxide, chlorobenzaldehyde, p-isopropylbenzylthiophenol, and ethyl acrylate; the dispersant is any one or two of KSO2000, KSO163, DW-404, and K2201; and the plasticizer is polyethylene glycol.

9. The application of the modified ceramic powder according to claim 7 or 8 in the preparation of 3D printing photocurable ceramic slurry, characterized in that, When using photocurable ceramic slurry for 3D printing, the process includes model slicing, curing depth testing, printing, debinding, and sintering.

10. The application of the modified ceramic powder according to claim 9 in the preparation of 3D printing photocurable ceramic slurry, characterized in that, The degreasing program is set as follows: 0-360℃, heating at a rate of 0.1-0.5℃ / min, holding for 1-2 hours; 360-440℃, heating at a rate of 0.1-0.5℃ / min, holding for 2-4 hours; 440-480℃, heating at a rate of 0.1-0.5℃ / min, holding for 1-2 hours; 480-650℃, heating at a rate of 0.1-0.5℃ / min, holding for 1-2 hours; 650-20℃, cooling at a rate of 1-5℃ / min. The sintering program is set as follows: 0-600℃ at a rate of 1-8℃ / min, holding for 1-2 hours; 600-1750℃ at a rate of 1-5℃ / min, holding for 1-3 hours; 1750-600℃ at a rate of 1-10℃ / min; 600-20℃ at a rate of 5-20℃ / min.

Images