Light-cured silicon nitride ceramic slurry and preparation method thereof

Abstract

The invention discloses light-cured silicon nitride ceramic slurry and a preparation method thereof, and relates to the technical field of light-cured printing. The preparation method comprises the following steps: S1, preparing modified silicon nitride powder: coating the surface of the silicon nitride powder with salt by using a recrystallization method to prepare the modified silicon nitride powder; and S2, carrying out ball milling on the modified silicon nitride powder and a sintering aid, uniformly mixing, drying, sieving, and adding into the resin premixed liquid to prepare the light-cured silicon nitride ceramic slurry. According to the invention, the surface of the silicon nitride powder is coated with the salt crystal layer by using the characteristic of cooling precipitation of the saturated salt solution, and the salt crystal layer is lower in refractive index and less in light absorption, so that the refractive index and absorbance of the silicon nitride powder can be effectively reduced by coating the surface of the silicon nitride powder with the salt crystal; the curing depth and the printing precision of the slurry are improved.

Description

Technical Field

[0001] The invention relates to the technical field of photocuring printing, and in particular to a photocuring silicon nitride ceramic slurry and a preparation method thereof. Background Art

[0002] Silicon nitride ceramics are widely used in various fields such as automobiles, energy, and aerospace due to their excellent comprehensive properties. With the refinement and complexity of engineering application fields, the demand for high-precision and complex structure silicon nitride is also increasing. However, the current high-precision and complex structure silicon nitride is mainly processed by traditional turning, milling, and grinding, which is costly and time-consuming. Therefore, research and exploration of the new technology of silicon nitride additive manufacturing is very necessary.

[0003] At present, additive manufacturing has emerged many printing processes due to its characteristics of rapid prototyping, high precision and complex prototyping, such as selective laser sintering (SLS), selective laser melting (SLM), binder jet forming (3DP), direct writing freeform prototyping (DIW), digital light processing (DLP), stereolithography (SLA), etc. Among them, SLS and SLM are mainly used in metal additive manufacturing because of the high melting and boiling points of ceramics; 3DP and DIW have poor precision and are only suitable for scenes with low requirements for precision and mechanical properties; SLA is a point light source exposure with a slow speed; so the current printing process that can take into account both high precision and high speed is DLP printing.

[0004] However, gray silicon nitride powder has high absorbance and refractive index. Compared with ceramics such as alumina, zirconium oxide, and aluminum nitride, silicon nitride ceramics are more difficult to obtain high curing depth and high printing accuracy. Faced with this problem, researchers have proposed methods such as high-temperature oxidation and co-precipitation coating of white additives on the surface of silicon nitride powder. However, the high-temperature oxidation method is energy-consuming and time-consuming, and has poor control over the oxygen content in the matrix, which will affect thermal conductivity, high-temperature performance, etc.; in order to obtain a uniform white coating layer, the co-precipitation method has a limited number of powders modified each time, and the formula of the white additive is limited, which limits the application of light-cured silicon nitride ceramics. Summary of the invention

[0005] The technical problem to be solved by the present invention is that the curing depth of silicon nitride ceramic slurry is low and the printing accuracy is poor, which limits the application of light-cured silicon nitride ceramics.

[0006] In order to solve the above problems, the present invention proposes the following technical solutions:

[0007] In one aspect, the present invention provides a method for preparing a photocurable silicon nitride ceramic slurry, comprising the following steps:

[0008] S1. Preparing modified silicon nitride powder: coating the surface of silicon nitride powder with salt by a recrystallization method to obtain modified silicon nitride powder;

[0009] S2. The modified silicon nitride powder and the sintering aid are ball-milled and mixed, dried and sieved, and added to the resin premix to obtain a light-cured silicon nitride ceramic slurry.

[0010] The present invention utilizes the characteristics of precipitation of saturated salt solution upon cooling to coat a layer of salt crystals on the surface of silicon nitride powder. Since the refractive index of the salt crystal layer is lower (such as the refractive index of KCL crystal is about 1.37), it absorbs less light. Therefore, coating the surface of silicon nitride powder with salt crystals can reduce the refractive index and absorbance of the silicon nitride powder to a certain extent, thereby making it more conducive to obtaining silicon nitride DLP printed products with high curing depth and high precision.

[0011] Furthermore, the step S1 specifically includes:

[0012] S11, adding salt and silicon nitride powder to deionized water at a temperature of 40 to 60° C. to prepare a suspension;

[0013] S12, lowering the temperature of the suspension until the salt content in the suspension is supersaturated, so that the salt precipitates from the suspension and is coated on the silicon nitride powder;

[0014] S13, filtering to obtain modified silicon nitride powder.

[0015] The present invention adds sieved silicon nitride powder to a high-concentration salt solution. As the temperature decreases, the salt solution is in an oversaturated state and solid salt crystals are precipitated. The precipitated solid salt crystals grow with silicon nitride grains as a template, thereby uniformly coating the surface of the silicon nitride powder with a layer of salt crystals.

[0016] Specifically, in step S13, the filtration is performed by suction filtration, and the filtered solid is dried in an oven at 50-60° C. to obtain modified silicon nitride powder.

[0017] Furthermore, in the step S12, the content of the precipitated salt is 0.1-10% of the mass of the silicon nitride powder.

[0018] Furthermore, the D50 particle size of the silicon nitride powder is 0.5 to 3 um.

[0019] Specifically, in step S2, it also includes adding silicon nitride balls with a diameter of 3 mm in the presence of a solvent and ball milling with a planetary ball mill, with a rotation speed of 200-300 r / min, a ball milling time of 1-3 hours, and the amount of silicon nitride balls used is 1.5-3 times the mass of the powder, and the solvent is at least one of ethanol, isopropanol, n-butanol, ethyl acetate, butyl acetate, butanone and cyclohexanone, preferably ethanol or n-butanol, and the amount is 2-3 times the mass of the powder.

[0020] After ball milling, the powder is dried in an oven at 50-60°C and sieved through 100-200 mesh.

[0021] Furthermore, the solid content of the photocurable silicon nitride ceramic slurry is 40-50 vol%.

[0022] Furthermore, the salt is KCl, NaCl or KNO 3 At least one of .

[0023] Furthermore, the resin premix consists of a resin, a dispersant and a photoinitiator; the resin is selected from at least one of BPA1OEODMA, TMPTA, HDDA, PPTTA, DOP and n-octanol; the dispersant is at least one of KOS-110, BYK-110 and BYK-111, and its dosage is 0.5-2wt% of the solid content; the photoinitiator is at least one of 819, 1000, 1156, TPO and TPO-L, and its dosage is 1-1.5wt% of the resin.

[0024] More preferably, the dispersant is at least one of KOS-110 and BYK-110, and the amount used is 0.5-2wt% of the solid content; the photoinitiator is one of 819 and TPO, and the amount used is 1wt% of the resin.

[0025] It should be noted that when preparing the slurry, the resin premix is ​​first mixed evenly by ultrasound, and the duration of ultrasound is 2 to 5 minutes. After the slurry is prepared, it is mixed by a homogenizer, and the homogenization speed is 1500 to 2000 r / min, and the homogenization time is 30 to 120 seconds.

[0026] Furthermore, the sintering aid comprises an alkali metal compound and a rare earth compound, wherein the alkali metal compound is MgO, MgF 2 、Al 2 O 3 and CaO, the rare earth compound is Y 2 O 3 , Yb 2 O 3 、CeO、Dy 2 O 3 , YF 3 and YbF 3 At least one of .

[0027] In another aspect, the present invention provides a photocurable silicon nitride ceramic slurry, which is prepared by the preparation method described above.

[0028] On the other hand, the present invention provides a photocurable silicon nitride ceramic, which is a photocurable silicon nitride ceramic slurry prepared by the preparation method described above, or the photocurable silicon nitride ceramic slurry is obtained by DLP printing, degreasing and sintering.

[0029] Furthermore, the process parameters for light-curing printing are: exposure time 3 to 12 seconds.

[0030] Compared with the prior art, the technical effects achieved by the present invention include:

[0031] The method for preparing a photocurable silicon nitride ceramic slurry provided by the present invention comprises the steps of S1, preparing a modified silicon nitride powder: coating the surface of the silicon nitride powder with salt by a recrystallization method to obtain a modified silicon nitride powder; S2, ball-milling and mixing the modified silicon nitride powder and a sintering aid, drying and sieving, and adding the mixture to a resin premix to obtain a photocurable silicon nitride ceramic slurry. The present invention utilizes the characteristics of precipitation of a saturated salt solution by cooling to coat a layer of salt crystals on the surface of the silicon nitride powder. Since the refractive index of the salt crystal layer is lower (such as the refractive index of KCL crystal is about 1.37), the absorption of light is also less, so coating the surface of the silicon nitride powder with salt crystals can effectively reduce the refractive index and absorbance of the silicon nitride powder, thereby improving the curing depth and printing accuracy of the slurry. Experiments show that, by coating and modifying silicon nitride powder with salt, the curing depth of silicon nitride slurry is increased by 14% to 23% and 21% to 31% respectively compared with the slurry made from unmodified powder and powder modified with a conventional modifier (KH570). This greatly improves the problems of low curing depth and poor precision caused by the large refractive index and absorbance of silicon nitride slurry during photocuring printing. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0033] Figure 1 This is the solubility curve of KCl crystals. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0036] It should also be understood that the terms used in this description of the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present invention. As used in the description of the embodiments of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms of "a", "an" and "the" are intended to include plural forms.

[0037] Example 1

[0038] This embodiment provides a photocurable silicon nitride ceramic slurry and a preparation method thereof, and a silicon nitride ceramic obtained from the slurry. The specific description is as follows:

[0039] Step S1: Weigh 37.92 g of KCl crystals, 30 g of Si with a D50 of 0.7 um 3 N 4 The powder was added with 100 ml of deionized water and mixed evenly, and the solution was heated to 40° C. to prepare a suspension.

[0040] Step S2: Lower the temperature of the suspension to 30°C to allow KCl to precipitate from the suspension and coat the Si 3 N 4 On the powder.

[0041] Step S3: Remove the deionized water in the suspension by filtration, and dry the solid in an oven at 60°C to obtain 29.99 g of modified silicon nitride powder. This is due to the loss caused by filtration (for example, part of the powder adheres to the filtration funnel and filter paper), and the actual amount obtained is less than the amount of the original silicon nitride powder.

[0042] Step S4: Weigh the modified silicon nitride powder according to the proportion: Y 2 O 3 ∶MgO=93∶2∶5 (wt%), mix, a total of 30g; add it to 100g anhydrous ethanol and 50g of 3mm silicon nitride balls in a planetary ball mill at 300r / min for 1 hour, filter to remove the silicon nitride balls, and then place the mixture in an oven at 60℃ to dry, and after drying, sieve with a 100-mesh sieve to obtain a mixed powder.

[0043] Step S5: 6 g of resin was weighed according to PPTTA:HDDA:DOP=5:2:3; 1 wt% of the powder was weighed as dispersant BYK-110, that is, 0.13 g; 1 wt% of the resin was weighed as photoinitiator TPO, that is, 0.06 g. After mixing, ultrasonic treatment was performed for 3 minutes to obtain a resin premix.

[0044] Step S6: 13 g of the mixed powder of step S4 was added to the resin premix of step S5, and mixed with a homogenizer at 2000 r / min for 60 s to prepare a silicon nitride ceramic slurry with a solid content of 40 vol%.

[0045] Step S7: Printing the obtained silicon nitride ceramic slurry with a photocuring printer, and obtaining a silicon nitride ceramic device after degreasing and sintering.

[0046] Example 2

[0047] This embodiment provides a photocurable silicon nitride ceramic slurry and a preparation method thereof, and a silicon nitride ceramic obtained from the slurry. The specific description is as follows:

[0048] Step S1: Weigh 38.52 g of KCl crystals, 30 g of Si with a D50 of 0.7 um 3 N 4 The powder was added with 100 ml of deionized water and mixed evenly, and the solution was heated to 40° C. to prepare a suspension.

[0049] Step S2: Lower the temperature of the suspension to 30°C to allow KCl to precipitate from the suspension and coat the Si 3 N 4 On the powder.

[0050] Step S3: remove the deionized water in the suspension by suction filtration, put the solid into an oven at 60° C. and dry it to obtain 30.58 g of modified silicon nitride powder.

[0051] Step S4: Weigh the modified silicon nitride powder according to the proportion: Y 2 O 3 ∶MgO=93∶2∶5 (wt%), mix, a total of 30g; add it to 100g anhydrous ethanol and 50g of 3mm silicon nitride balls in a planetary ball mill at 300r / min for 1 hour, filter to remove the silicon nitride balls, and then place the mixture in an oven at 60℃ to dry, and after drying, sieve with a 100-mesh sieve to obtain a mixed powder.

[0052] Step S5: 6 g of resin was weighed according to PPTTA:HDDA:DOP=5:2:3; 1 wt% of the powder was weighed as dispersant BYK-110, that is, 0.13 g; 1 wt% of the resin was weighed as photoinitiator TPO, that is, 0.06 g. After mixing, ultrasonic treatment was performed for 3 minutes to obtain a resin premix.

[0053] Step S6: 13 g of the mixed powder of step S4 was added to the resin premix of step S5, and mixed with a homogenizer at 2000 r / min for 60 s to prepare a silicon nitride ceramic slurry with a solid content of 40 vol%.

[0054] Step S7: Printing the obtained silicon nitride ceramic slurry with a photocuring printer to obtain a silicon nitride ceramic device.

[0055] Example 3

[0056] This embodiment provides a photocurable silicon nitride ceramic slurry and a preparation method thereof, and a silicon nitride ceramic obtained from the slurry. The specific description is as follows:

[0057] Step S1: Weigh 39.12 g of KCl crystals, 30 g of Si with a D50 of 0.7 um 3 N 4 The powder was added with 100 ml of deionized water and mixed evenly, and the solution was heated to 40° C. to prepare a suspension.

[0058] Step S2: Lower the temperature of the suspension to 30°C to allow KCl to precipitate from the suspension and coat the Si 3 N 4 On the powder.

[0059] Step S3: remove the deionized water in the suspension by suction filtration, put the solid into an oven at 60° C. and dry it to obtain 31.16 g of modified silicon nitride powder.

[0060] Step S4: Weigh the modified silicon nitride powder according to the proportion: Y 2 O 3 ∶MgO=93∶2∶5 (wt%), mix, a total of 30g; add it to 100g anhydrous ethanol and 50g of 3mm silicon nitride balls in a planetary ball mill at 300r / min for 1 hour, filter to remove the silicon nitride balls, and then place the mixture in an oven at 60℃ to dry, and after drying, sieve with a 100-mesh sieve to obtain a mixed powder.

[0061] Step S5: 6 g of resin was weighed according to PPTTA:HDDA:DOP=5:2:3; 1 wt% of the powder was weighed as dispersant BYK-110, that is, 0.13 g; 1 wt% of the resin was weighed as photoinitiator TPO, that is, 0.06 g. After mixing, ultrasonic treatment was performed for 3 minutes to obtain a resin premix.

[0062] Step S6: 13 g of the mixed powder of step S4 was added to the resin premix of step S5, and mixed with a homogenizer at 2000 r / min for 60 s to prepare a silicon nitride ceramic slurry with a solid content of 40 vol%.

[0063] Step S7: Printing the obtained silicon nitride ceramic slurry with a photocuring printer to obtain a silicon nitride ceramic device.

[0064] Example 4

[0065] This embodiment provides a photocurable silicon nitride ceramic slurry and a preparation method thereof, and a silicon nitride ceramic obtained from the slurry. The specific description is as follows:

[0066] Step S1: Weigh 39.72 g of KCl crystals, 30 g of Si with a D50 of 0.7 um 3 N 4 The powder was added with 100 ml of deionized water and mixed evenly, and the solution was heated to 40° C. to prepare a suspension.

[0067] Step S2: Lower the temperature of the suspension to 30°C to allow KCl to precipitate from the suspension and coat the Si 3 N 4 On the powder.

[0068] Step S3: remove the deionized water in the suspension by suction filtration, put the solid into an oven at 60° C. and dry it to obtain 31.75 g of modified silicon nitride powder.

[0069] Step S4: Weigh the modified silicon nitride powder according to the proportion: Y 2 O 3 ∶MgO=93∶2∶5 (wt%), mix, a total of 30g; add it to 100g anhydrous ethanol and 50g of 3mm silicon nitride balls in a planetary ball mill at 300r / min for 1 hour, filter to remove the silicon nitride balls, and then place the mixture in an oven at 60℃ to dry, and after drying, sieve with a 100-mesh sieve to obtain a mixed powder.

[0070] Step S5: 6 g of resin was weighed according to PPTTA:HDDA:DOP=5:2:3; 1 wt% of the powder was weighed as dispersant BYK-110, that is, 0.13 g; 1 wt% of the resin was weighed as photoinitiator TPO, that is, 0.06 g. After mixing, ultrasonic treatment was performed for 3 minutes to obtain a resin premix.

[0071] Step S6: 13 g of the mixed powder of step S4 was added to the resin premix of step S5, and mixed with a homogenizer at 2000 r / min for 60 s to prepare a silicon nitride ceramic slurry with a solid content of 40 vol%.

[0072] Step S7: Printing the obtained silicon nitride ceramic slurry with a photocuring printer to obtain a silicon nitride ceramic device.

[0073] Example 5

[0074] This embodiment provides a photocurable silicon nitride ceramic slurry and a preparation method thereof, and a silicon nitride ceramic obtained from the slurry. The specific description is as follows:

[0075] Step S1: Weigh 40.32 g of KCl crystals, 30 g of Si with a D50 of 0.7 um 3 N 4 The powder was added with 100 ml of deionized water and mixed evenly, and the solution was heated to 50° C. to prepare a suspension.

[0076] Step S2: Lower the temperature of the suspension to 30°C to allow KCl to precipitate from the suspension and coat the Si 3 N 4 On the powder.

[0077] Step S3: remove the deionized water in the suspension by suction filtration, put the solid into an oven at 60° C. and dry it to obtain 32.34 g of modified silicon nitride powder.

[0078] Step S4: Weigh the modified silicon nitride powder according to the proportion: Y 2 O 3 ∶MgO=93∶2∶5 (wt%), mix, a total of 30g; add it to 100g anhydrous ethanol and 50g of 3mm silicon nitride balls in a planetary ball mill at 300r / min for 1 hour, filter to remove the silicon nitride balls, and then place the mixture in an oven at 60℃ to dry, and after drying, sieve with a 100-mesh sieve to obtain a mixed powder.

[0079] Step S5: 6 g of resin was weighed according to PPTTA:HDDA:DOP=5:2:3; 1 wt% of the powder was weighed as dispersant BYK-110, that is, 0.13 g; 1 wt% of the resin was weighed as photoinitiator TPO, that is, 0.06 g. After mixing, ultrasonic treatment was performed for 3 minutes to obtain a resin premix.

[0080] Step S6: 13 g of the mixed powder of step S4 was added to the resin premix of step S5, and mixed with a homogenizer at 2000 r / min for 60 s to prepare a silicon nitride ceramic slurry with a solid content of 40 vol%.

[0081] Step S7: Printing the obtained silicon nitride ceramic slurry with a photocuring printer to obtain a silicon nitride ceramic device.

[0082] Example 6

[0083] This embodiment provides a photocurable silicon nitride ceramic slurry and a preparation method thereof, and a silicon nitride ceramic obtained from the slurry. The specific description is as follows:

[0084] Step S1: Weigh 37.92 g of KCl crystals, 30 g of Si with a D50 of 0.7 um 3 N 4 The powder was added with 100 ml of deionized water and mixed evenly, and the solution was heated to 40° C. to prepare a suspension.

[0085] Step S2: Lower the temperature of the suspension to 30°C to allow KCl to precipitate from the suspension and coat the Si 3 N 4 On the powder.

[0086] Step S3: remove the deionized water in the suspension by suction filtration, put the solid into an oven at 60° C. and dry it to obtain 29.99 g of modified silicon nitride powder.

[0087] Step S4: Weigh the modified silicon nitride powder according to the proportion: Y 2 O 3 ∶MgO=93∶2∶5 (wt%), mix, a total of 30g; add it to 100g anhydrous ethanol and 50g of 3mm silicon nitride balls in a planetary ball mill at 300r / min for 1 hour, filter to remove the silicon nitride balls, and then place the mixture in an oven at 60℃ to dry, and after drying, sieve with a 100-mesh sieve to obtain a mixed powder.

[0088] Step S5: weigh 5g of resin according to PPTTA:HDDA:DOP=5:2:3; weigh 2wt% of the powder dispersant BYK-110, that is, 0.26g; weigh 1wt% of the resin photoinitiator TPO, that is, 0.06g. After mixing, ultrasonicate for 3min to obtain a resin premix.

[0089] Step S6: 16.25 g of the mixed powder of step S4 was added to the resin premix of step S5, and mixed with a homogenizer at 2000 r / min for 60 s to prepare a silicon nitride ceramic slurry with a solid content of 50 vol%.

[0090] Step S7: Printing the obtained silicon nitride ceramic slurry with a photocuring printer, and obtaining a silicon nitride ceramic device after degreasing and sintering.

[0091] Comparative Example 1

[0092] The difference between this comparative example and Example 1 is that the silicon nitride powder in this comparative example is not subjected to salt coating treatment. The specific preparation process is as follows:

[0093] Step S1: Weigh Si in proportion 3 N 4 (D50=0.7)∶Y 2 O 3 A total of 30 g of mixed powder of ∶MgO=93∶2∶5 (wt%) was added into 100 g of anhydrous ethanol and 50 g of 3 mm silicon nitride balls, and mixed and ball-milled at 300 r / min in a planetary ball mill for 1 hour. The silicon nitride balls were filtered out, and then the mixture was dried in an oven at 60°C. After drying, it was sieved with a 100-mesh sieve to obtain a mixed powder.

[0094] Step S2: weigh 6g of resin according to PPTTA:HDDA:DOP=5:2:3; weigh 1wt% of the powder dispersant BYK-110, that is, 0.13g; weigh 1wt% of the resin photoinitiator TPO, that is, 0.06g; mix and ultrasonicate for 3min to obtain a resin premix.

[0095] Step S3: 13 g of the mixed powder of step S1 was added to the resin premix of step S2, and mixed with a homogenizer at 2000 r / min for 60 s to prepare a silicon nitride ceramic slurry with a solid content of 40 vol%.

[0096] Step S4: Printing the obtained silicon nitride ceramic slurry with a photocuring printer to obtain a silicon nitride ceramic device.

[0097] Comparative Example 2

[0098] The difference between this comparative example and Example 1 is that in this comparative example, silicon nitride powder is modified by KH570. The specific preparation process is as follows:

[0099] Step S1: Weigh Si in proportion 3 N 4 (D50=0.7)∶Y 2 O 3 A total of 30g of mixed powder with ∶MgO=93:2:5 (wt%), 2wt% of the mass of the mixed powder, i.e. 0.6g of KH570, was weighed, the mixed powder and KH570 were added with 100g of anhydrous ethanol and 50g of 3mm silicon nitride balls, and mixed and ball-milled in a planetary ball mill at 300r / min for 1 hour, the silicon nitride balls were filtered out, and the mixture was placed in an oven at 60°C for drying. After drying, it was sieved with a 100-mesh sieve to obtain a KH570-modified mixed powder.

[0100] Step S2: weigh 6g of resin according to PPTTA:HDDA:DOP=5:2:3; weigh 1wt% of the powder dispersant BYK-110, that is, 0.13g; weigh 1wt% of the resin photoinitiator TPO, that is, 0.06g; mix and ultrasonicate for 3min to obtain a resin premix.

[0101] Step S3: 13 g of the mixed powder of step S1 was added to the resin premix of step S2, and mixed with a homogenizer at 2000 r / min for 60 s to prepare a silicon nitride ceramic slurry with a solid content of 40 vol%.

[0102] Step S4: Printing the obtained silicon nitride ceramic slurry with a photocuring printer to obtain a silicon nitride ceramic device.

[0103] Table 1. At 12mJ / cm 2 Curing depth (μm) of silicon nitride slurry prepared in Example 1 and Comparative Examples 1-2 at different curing times under exposure energy of

[0104]

[0105] Table 2. At 120.1 mJ / cm 2 The curing depth of the silicon nitride slurry prepared in different embodiments at the total exposure energy of

[0106]

[0107]

[0108] Note: Example of calculation method for KCl precipitation amount: See the solubility of KCl crystals at different temperatures. Figure 1Taking 30g silicon nitride powder as the main body, the solubility of KCl at 60°C is 45.8g, and the theoretical solubility of KCl at 40°C is 40.1g; at 60°C, 40.7g KCl is added to 100ml deionized water, and then the solution temperature is lowered to 40°C. Theoretically, 0.6g KCl will precipitate, which accounts for 2wt% of 30g silicon nitride powder. Therefore, the theoretical precipitation amount is 2wt%.

[0109] As shown in Table 1 and Table 2, the embodiment of the present invention sets the KCl dosage in the embodiment with a gradient of 2wt% of the theoretical precipitation amount of KCl. The curing depth of the slurry in the embodiment with a theoretical precipitation amount of KCl of 2% to 10% is increased by 14% to 23% compared with the unmodified silicon nitride powder, and by 21% to 31% compared with the 2wt% KH570 modified silicon nitride powder. Since the surface of the modified silicon nitride powder of the present invention is coated with KCl crystals, the absorption and scattering effect of light on the surface is reduced compared with the unmodified silicon nitride powder, thereby increasing the curing depth under the same total exposure energy. Therefore, under the same curing depth, the total exposure energy required for the KCl-modified silicon nitride slurry is reduced, and the overexposure width is correspondingly reduced, thereby improving the printing accuracy.

[0110] In the embodiment of the present invention, KCl crystal is used as an example to recrystallize and coat silicon nitride powder. In other embodiments, NaCl or KNO 3 The crystals recrystallize and coat the silicon nitride powder.

[0111] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0112] The above is a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for preparing a photocurable silicon nitride ceramic slurry, characterized in that: The following steps are involved: S1. Preparing modified silicon nitride powder: coating the surface of silicon nitride powder with salt by a recrystallization method to obtain modified silicon nitride powder; S2. The modified silicon nitride powder and the sintering aid are ball-milled and mixed, dried and sieved, and added to the resin premix to obtain a light-cured silicon nitride ceramic slurry.

2. The method for preparing the photocurable silicon nitride ceramic slurry according to claim 1, characterized in that: The step S1 specifically includes: S11, adding salt and silicon nitride powder to deionized water at a temperature of 40 to 60° C. to prepare a suspension; S12, lowering the temperature of the suspension until the salt content in the suspension is supersaturated, so that the salt precipitates from the suspension and is coated on the silicon nitride powder; S13, filtering to obtain modified silicon nitride powder.

3. The method for preparing the photocurable silicon nitride ceramic slurry according to claim 2, characterized in that: In the step S12, the content of the precipitated salt is 0.1-10% of the mass of the silicon nitride powder.

4. The method for preparing the photocurable silicon nitride ceramic slurry according to claim 1, characterized in that: The D50 particle size of the silicon nitride powder is 0.5-3 um.

5. The method for preparing the photocurable silicon nitride ceramic slurry according to claim 1, characterized in that: The solid content of the photocurable silicon nitride ceramic slurry is 40-50 vol%.

6. The method for preparing the photocurable silicon nitride ceramic slurry according to claim 1, characterized in that: The salt is at least one of KCl, NaCl or KNO3.

7. The method for preparing the photocurable silicon nitride ceramic slurry according to claim 1, characterized in that: The resin premix consists of a resin, a dispersant and a photoinitiator; the resin is selected from at least one of BPA1OEODMA, TMPTA, HDDA, PPTTA, DOP and n-octanol; the dispersant is at least one of KOS-110, BYK-110 and BYK-111, and its dosage is 0.5-2wt% of the solid content; the photoinitiator is at least one of 819, 1000, 1156, TPO and TPO-L, and its dosage is 1-1.5wt% of the resin.

8. The method for preparing the photocurable silicon nitride ceramic slurry according to claim 1, characterized in that: The sintering aid comprises an alkali metal compound and a rare earth compound, wherein the alkali metal compound is at least one of MgO, MgF2, Al2O3 and CaO, and the rare earth compound is at least one of Y2O3, Yb2O3, CeO, Dy2O3, YF3 and YbF3.

9. A photocurable silicon nitride ceramic slurry, characterized in that: Prepared by the preparation method according to any one of claims 1 to 7.

10. A photocured silicon nitride ceramic, characterized in that: The photocurable silicon nitride ceramic slurry is prepared by the preparation method according to any one of claims 1 to 7, or is obtained by DLP printing, degreasing and sintering the photocurable silicon nitride ceramic slurry according to claim 8.

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