Photocuring 3D printing-based phosphate enhanced aluminum nitride ceramic and preparation method thereof

Abstract

The invention relates to the technical field of ceramic additive manufacturing, in particular to phosphate enhanced aluminum nitride ceramic based on photocuring 3D printing and a preparation method thereof. The invention discloses a preparation and printing method for enhancing thermo-mechanical properties of photocuring 3D printing AlN-based ceramic by adding magnesium dihydrogen phosphate, and the preparation and printing method specifically comprises the following steps: adding magnesium dihydrogen phosphate into three resins, namely o-phenyl phenoxyethyl acrylate, 1, 6-hexanediol diacrylate and ethoxylated pentaerythritol tetraacrylate, stirring, and carrying out ultrasonic treatment to obtain the photocuring 3D printing AlN-based ceramic. And the curing depth, the density and the mechanical-thermal performance of the photocuring 3D printing AlN ceramic slurry can be remarkably improved. The obtained 3D printing AlN-based ceramic can be applied to a thermal management device.

Description

Technical Field

[0001] This invention relates to the field of ceramic additive manufacturing technology, specifically to a phosphate-reinforced aluminum nitride ceramic based on photopolymerization 3D printing and its preparation method. Background Technology

[0002] In today's wave of miniaturization, integration, and high power in electronic devices, efficient heat dissipation has become a core bottleneck restricting performance and reliability. Aluminum nitride ceramics possess a coefficient of thermal expansion that is highly compatible with semiconductor chips (such as silicon and gallium arsenide). This compatibility significantly reduces interfacial thermal stress during drastic temperature changes, greatly improving the long-term reliability and lifespan of the packaging structure. Furthermore, it exhibits good mechanical strength, excellent chemical stability, low dielectric constant and loss, and precision machinability. With its series of superior comprehensive properties, aluminum nitride ceramics have undeniably established their key core position in advanced heat dissipation, especially in high-power, high-density electronic packaging.

[0003] However, since photopolymerization printing requires resin, the evaporation of the resin during the debinding and sintering process inevitably introduces porosity. This results in the density of photopolymerized AlN ceramics being lower than that of AlN ceramics sintered using traditional methods, which is one of the unavoidable drawbacks of photopolymerization printing itself. Due to the lower density, the printed AlN ceramics often fail to meet the expected mechanical and thermal properties. Summary of the Invention

[0004] To achieve the above objectives, this invention provides a phosphate-reinforced aluminum nitride ceramic based on photopolymerization 3D printing and its preparation method. The aluminum nitride ceramic of this invention exhibits improved thermal conductivity and flexural strength, enabling it to serve under more demanding operating conditions. The technical solution of this invention is implemented as follows: In a first aspect, the present invention provides a method for preparing phosphate-reinforced aluminum nitride ceramics based on photopolymerization 3D printing, comprising the following steps: S1. Prepare aluminum nitride photocurable slurry, wherein the aluminum nitride photocurable slurry comprises aluminum nitride powder, photocurable resin, phosphate, dispersant, photoinitiator, sintering aid and defoamer; S2. The above aluminum nitride photocurable slurry is photocured and printed. After degreasing, decarburizing and sintering, phosphate-reinforced aluminum nitride ceramics are obtained.

[0005] Based on the above scheme, preferably, the phosphate is magnesium dihydrogen phosphate.

[0006] Specifically, adding magnesium dihydrogen phosphate as a high-temperature binder to aluminum nitride slurry can effectively reduce the distance between ceramic powders, improving both curing performance and density. The mechanism is as follows: magnesium dihydrogen phosphate bonds with Al ions generated on the surface of AlN particles, and adjacent magnesium dihydrogen phosphate particles are bonded together through dehydration condensation, thus tightly binding the AlN particles together. This helps shorten the distance between AlN particles, thereby increasing the curing depth of the slurry. During the degreasing and decarburization stage, magnesium dihydrogen phosphate also undergoes a dehydration condensation reaction, further increasing the density of AlN ceramics and improving their thermal properties. Furthermore, during sintering, it decomposes to produce magnesium oxide, which reacts with aluminum oxide to form magnesium aluminum spinel, enhancing the mechanical properties of AlN ceramics.

[0007] Based on the above scheme, preferably, the amount of magnesium dihydrogen phosphate used is 3% to 9% of the sum of the weights of aluminum nitride powder and sintering aid.

[0008] More preferably, the amount of magnesium dihydrogen phosphate used is 7% of the sum of the weights of aluminum nitride powder and sintering aid.

[0009] Specifically, a low content of magnesium dihydrogen phosphate cannot achieve densification and has limited effect on improving the performance of AlN ceramics. On the other hand, an excessively high content of magnesium dihydrogen phosphate will lead to the generation of excessive phosphorus oxide, which will vaporize during sintering, resulting in porosity and defects that significantly reduce the performance of AlN ceramics.

[0010] Based on the above scheme, preferably, the photocurable resin includes o-phenylphenoxyethyl acrylate, 1,6-hexanediol diacrylate and ethoxylated pentaerythritol tetraacrylate; the dispersant includes a polymer copolymer dispersant; the photoinitiator includes bis(2,4,6-trimethylbenzoyl)diphenylphosphine oxide; and the sintering aid includes yttrium trioxide powder.

[0011] More preferably, the mass ratio of the aluminum nitride powder to yttrium oxide is (95-97):(3-5).

[0012] Specifically, this content ratio ensures that yttrium oxide acts as a sintering aid without affecting the bonding effect of magnesium dihydrogen phosphate.

[0013] More preferably, the aluminum nitride powder has an average particle size of 1.0~1.2μm, the yttrium oxide powder has an average particle size of 50nm, and the magnesium dihydrogen phosphate powder has an average particle size of 0.5~1μm.

[0014] Specifically, using aluminum nitride powder with a particle size of 1~1.2μm can ensure high performance of AlN ceramics and will not cause the slurry to become too viscous to print due to excessively small particle size.

[0015] Based on the above scheme, preferably, the mass ratio of o-phenylphenoxyethyl acrylate, 1,6-hexanediol diacrylate and ethoxylated pentaerythritol tetraacrylate is 5:4:1.

[0016] Specifically, the addition of magnesium dihydrogen phosphate will cause a bonding reaction with AlN particles, bringing them closer together, which will lead to a decrease in rheological properties. By adjusting the resin formulation and adding a higher proportion of low-viscosity resin, the rheological properties of the entire slurry can be improved to ensure that the slurry can be printed normally.

[0017] Based on the above scheme, preferably, the preparation method of the aluminum nitride photocurable slurry in step S1 includes: adding aluminum nitride powder, photocurable resin, phosphate, dispersant, photoinitiator and sintering aid to anhydrous ethanol and placing it in a ball milling jar, using zirconia ball milling beads as the ball milling medium, and ball milling for 9.5~10.5h.

[0018] More preferably, after ball milling and mixing, the mixture is dried in a drying oven and then ground through a 100-mesh sieve to obtain a mixed powder; the ball milling speed is 350 rpm.

[0019] Based on the above scheme, preferably, in step S2, the photopolymerization printing parameters include: an exposure intensity of 19.38~32.81mW / cm². 2 The printing layer thickness is 25μm; the exposure time is 5~15s; and aluminum nitride ceramic green bodies are obtained after layer-by-layer printing.

[0020] Based on the above scheme, preferably, in step S2, the degreasing process includes: placing the photocured aluminum nitride ceramic green body in a protective atmosphere, raising the temperature from 25°C to 600°C at a rate of 0.1°C / min to 1°C / min, and holding it at 150°C, 250°C, 350°C and 450°C for 60 to 240 minutes respectively.

[0021] Based on the above scheme, preferably, in step S2, the decarburization process includes: placing the degreased aluminum nitride ceramic in a muffle furnace, raising the temperature from 25°C to 1000°C at a heating rate of 0.5°C / min to 5°C / min, and holding it at 350°C and 600°C for 60 minutes respectively.

[0022] Specifically, magnesium dihydrogen phosphate undergoes a dehydration reaction at 200~400℃, and decomposes into magnesium pyrophosphate at 500~800℃.

[0023] Based on the above scheme, preferably, in step S2, the sintering process includes: placing the degreased and decarburized aluminum nitride ceramic in a protective atmosphere for pressureless sintering, first holding it at 1600℃ for 1 hour, and then holding it at 1850℃ for 3 hours.

[0024] Specifically, magnesium oxide reacts with aluminum oxide at 1400~1600℃ to form magnesium aluminum spinel.

[0025] In a second aspect, the present invention provides a phosphate-reinforced aluminum nitride ceramic obtained by the preparation method described in the first aspect.

[0026] Compared with the prior art, the advantages of the present invention are as follows: (1) This invention adds magnesium dihydrogen phosphate as a high-temperature binder to formulate the photocurable printing slurry, which improves the curing depth of the photocurable 3D printing AlN ceramic slurry and is beneficial for rapidly printing high-precision, defect-free AlN-based ultrathin precision porous ceramic blanks. Furthermore, during the sintering process, magnesium dihydrogen phosphate can effectively pull AlN ceramic particles closer together, improve density and overcome the inherent defects of photocurable printing, thereby improving the mechanical and thermal properties of photocurable printed AlN ceramics. This invention enables AlN-based ceramics for thermal management applications, allowing aluminum nitride ceramic parts to serve in more demanding environments.

[0027] (2) The resin formulation used in this invention is a new resin formulation with an adjusted ratio of o-phenylphenoxyethyl acrylate: 1,6-hexanediol diacrylate: ethoxylated pentaerythritol tetraacrylate of 5:4:1. This formulation can eliminate the problem of decreased rheological properties after adding magnesium dihydrogen phosphate and reduce the viscosity of AlN ceramic slurry. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram illustrating the principle by which magnesium dihydrogen phosphate can improve density and curing performance in this invention. Figure 2 The morphology of the complete ceramic green sample obtained by photocuring and printing the aluminum nitride paste prepared in Example 1 of the present invention; Figure 3 The mechanical and thermal properties of ceramics obtained by photocuring and printing slurries prepared with different phosphate contents in Examples 1-4 and Comparative Examples 1-4 of the present invention are shown. Figure 4 This is a SEM image of the aluminum nitride ceramic prepared in Example 1 of this invention after sintering. Figure 5This is a comparison of the viscosity of slurries prepared with different phosphate contents in Examples 1-4 of the present invention; Figure 6 This is a comparison of the viscosity of slurries prepared with different phosphate contents in Example 1 and Comparative Examples 2-4 of the present invention; Figure 7 This is a comparison of the curing depth of slurries prepared with different phosphate contents in Examples 1-4 of the present invention; Figure 8 This is a comparison of the curing depth of slurries prepared with different phosphate contents in Example 1 and Comparative Examples 2-4 of the present invention. Detailed Implementation

[0030] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0031] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0032] In this document, the terms “containing,” “comprising,” or “including” are open-ended expressions, meaning they include the contents specified in this invention but do not exclude other aspects.

[0033] In this document, the terms “optionally,” “optionally,” or “optionally” generally refer to an event or condition that may, but may not, occur, and the description includes both cases in which the event or condition occurs and cases in which the event or condition does not occur.

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0035] The 3D printer used in this invention is the Cerastation 160 ceramic 3D printer developed by Jiangsu Qiandu Technology Co., Ltd. The ceramic printing layer thickness used for testing was 25 μm, and the exposure energy was 19.38~32.81 mW / cm². 2 The exposure time is 5-15 seconds. Unless otherwise specified, all raw materials used in this invention are commercially available in the field; details are shown in Table 1.

[0036] Table 1 Raw materials used in this invention

[0037] Example 1 This embodiment provides a phosphate-reinforced aluminum nitride ceramic based on photopolymerization 3D printing and its preparation method, wherein the amount of magnesium dihydrogen phosphate used is 7% of the total weight of aluminum nitride powder and sintering aid, and includes the following steps: Preparation of aluminum nitride photocurable slurry: Weigh 8.46g of monofunctional photosensitive resin reactive diluent o-phenylphenoxyethyl acrylate, 6.77g of difunctional photosensitive resin reactive diluent 1,6-hexanediol diacrylate, 1.69g of tetrafunctional photosensitive resin reactive diluent ethoxylated pentaerythritol tetraacrylate, 1g of photoinitiator phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 47.5g of aluminum nitride powder, 2.5g of yttrium oxide sintering aid, 3.5g of magnesium dihydrogen phosphate powder, and 1g of dispersant SP-710 into a plastic container, add 20g of zirconia ball milling beads, and ball mill at 350 rpm for 10h to obtain the photocurable slurry; 2) Photopolymer 3D printing: A Cerastation 160 ceramic printer (Jiangsu Qiandu Technology Co., Ltd.) was used, with an exposure intensity of 25.23 mW / cm². 2 The single exposure time was 10 seconds, the single layer thickness was 25 μm, and the printed part was ultrasonically cleaned twice with anhydrous ethanol for 1 minute each time; the printed ceramic preform is shown in the image below. Figure 2 The uniform wall thickness and absence of obvious cracks indicate that the printing result is good. 3) Degreasing: A two-step degreasing method is used to degrease the printed blank. The specific steps are as follows: The printed sample is placed in a boron nitride crucible, and the crucible is placed in a tube furnace for degreasing treatment. The first step is low-temperature degreasing. First, the temperature is increased from 25℃ to 250℃ at a heating rate of 1℃ / min under a nitrogen atmosphere, and then held at 150℃ and 250℃ for 1 hour, and then cooled to room temperature. The second step is high-temperature degreasing. The temperature is increased to 250℃ at a heating rate of 1℃ and held for 1 hour, and then increased to 600℃ at a heating rate of 0.1℃ / min, and then held at 350℃ and 450℃ for 1 hour and 4 hours, respectively, and then cooled to room temperature. 4) Decarburization: The degreased ceramic body is placed in a low-temperature muffle furnace and heated from 25°C at a rate of 0.5°C / min. It is then held at 350°C and 600°C for 60 min respectively. Subsequently, the temperature is increased to 1000°C at a rate of 5°C / min. After the program is completed, the air is allowed to cool naturally to room temperature. 5) Sintering: After decarburization, sintering is carried out under a nitrogen atmosphere, first at 1600℃ for 1 hour, then at 1850℃ for 3 hours; phosphate-reinforced aluminum nitride ceramics are obtained. Figure 3 and Figure 4 As shown, a relatively complete precision structure and microstructure are obtained after sintering. The mechanical properties can reach 392.9 MPa and the thermal conductivity can reach 183.9 W / mK, as tested by the four-point bending test method.

[0038] Example 2

[0039] This embodiment provides a phosphate-reinforced aluminum nitride ceramic based on photopolymerization 3D printing and its preparation method. The difference from Embodiment 1 is that the amount of magnesium dihydrogen phosphate used is 3% of the total weight of the aluminum nitride powder and sintering aid, i.e., 1.5g of magnesium dihydrogen phosphate powder is used. The remaining steps are the same as in Embodiment 1. The mechanical properties and thermal conductivity test results of the aluminum nitride ceramic prepared in Embodiment 2 are as follows: Figure 3 As shown, the mechanical and thermal properties of AlN ceramics with 3% magnesium dihydrogen phosphate added are significantly lower than those of Example 1.

[0040] Example 3

[0041] This embodiment provides a phosphate-reinforced aluminum nitride ceramic based on photopolymerization 3D printing and its preparation method. The difference from Embodiment 1 is that the amount of magnesium dihydrogen phosphate used is 5% of the total weight of the aluminum nitride powder and sintering aid, i.e., 2.5g of magnesium dihydrogen phosphate powder is used. The remaining steps are the same as in Embodiment 1. The mechanical properties and thermal conductivity test results of the aluminum nitride ceramic prepared in Embodiment 3 are as follows: Figure 3 As shown, the mechanical and thermal properties of AlN ceramics with 5% magnesium dihydrogen phosphate added are significantly lower than those of Example 1.

[0042] Example 4

[0043] This embodiment provides a phosphate-reinforced aluminum nitride ceramic based on photopolymerization 3D printing and its preparation method. The difference from Embodiment 1 is that the amount of magnesium dihydrogen phosphate used is 9% of the total weight of the aluminum nitride powder and sintering aid, i.e., 4.5g of magnesium dihydrogen phosphate powder is used. The remaining steps are the same as in Embodiment 1. The mechanical properties and thermal conductivity test results of the aluminum nitride ceramic prepared in Embodiment 4 are as follows: Figure 3 As shown, the mechanical and thermal properties of AlN ceramics with 9% magnesium dihydrogen phosphate added are significantly lower than those of Example 1.

[0044] Comparative Example 1

[0045] The difference between this comparative example and Example 1 is that phosphate is not added, while the proportions of other additives are the same as in Example 1, such as... Figure 3 As shown, the mechanical and thermal properties of AlN ceramics without phosphate addition are significantly lower than those in Example 1.

[0046] Comparative Example 2

[0047] The difference between this comparative example and Example 1 is that the amount of magnesium dihydrogen phosphate used is 11% of the total weight of aluminum nitride powder and sintering aids, while the proportions of other additives are the same as in Example 1. The test results for its mechanical properties and thermal conductivity are as follows: Figure 3 As shown.

[0048] Comparative Example 3

[0049] The difference between this comparative example and Example 1 is that the amount of magnesium dihydrogen phosphate used is 13% of the total weight of aluminum nitride powder and sintering aids, while the proportions of other additives are the same as in Example 1. The test results for its mechanical properties and thermal conductivity are as follows: Figure 3 As shown.

[0050] Comparative Example 4

[0051] The difference between this comparative example and Example 1 is that the amount of magnesium dihydrogen phosphate used is 15% of the total weight of aluminum nitride powder and sintering aids, while the proportions of other additives are the same as in Example 1. The test results for its mechanical properties and thermal conductivity are as follows: Figure 3 As shown.

[0052] Comparative Example 5

[0053] The difference between this comparative example and Example 1 is that magnesium dihydrogen phosphate is replaced with an equal mass of aluminum dihydrogen phosphate, while the proportions of other additives remain the same as in Example 1. Its rheological properties were tested. At a shear rate of 400 (1 / s), the rheological properties measured using a rheological rotator were 703.2 Pa*s, significantly higher than in Example 1, and it failed to achieve normal printing results. This is because aluminum dihydrogen phosphate has a stronger adhesive effect compared to magnesium dihydrogen phosphate, leading to a large aggregation of AlN particles and thus a substantial increase in viscosity.

[0054] Comparative Example 6

[0055] The difference between this comparative example and Example 1 is that magnesium dihydrogen phosphate was replaced with an equal mass of magnesium oxide, while the proportions of other additives remained the same as in Example 1. The curing performance and the mechanical and thermal properties after sintering at 1850℃ were tested. The curing performance was tested using a Cerastation 160 UV curing instrument from Jiangsu Qiandu Company, and the results are shown in Table 2. The mechanical properties after sintering were 289.4 MPa, and the thermal properties were 152.7 W / mK, lower than those of Example 1. This is because magnesium oxide does not provide any beneficial effect during the printing stage.

[0056] Comparative Example 7

[0057] The difference between this comparative example and Example 1 lies in the addition of a different resin ratio: o-phenylphenoxyethyl acrylate: 1,6-hexanediol diacrylate: ethoxylated pentaerythritol tetraacrylate in a mass ratio of 5:3:2. Its rheological properties were tested. At a shear rate of 400 (1 / s), its rheological properties were 467.3 Pa*s, significantly higher than those of Example 1. This has a certain impact on the actual printing process, affecting the quality of the printed green body and interlayer bonding.

[0058] Table 2. Curing depth of slurries prepared in the examples and comparative examples.

[0059] Figure 5 and Figure 6 The graph shows a comparison of the viscosity of the slurry after mixing in Experiment 1 with that after mixing in Examples 2, 3, 4 and Comparative Examples 1 to 4. It can be seen that when the amount of magnesium dihydrogen phosphate added is 3% to 9%, its rheological properties are good and can support complete printing. Figure 7 and Figure 8 Table 2 shows a comparison of the curing depth of the slurry mixed in Experimental Example 1 with that of Examples 2, 3, 4, and Comparative Examples 1-4. When the magnesium dihydrogen phosphate content is 3%–9%, ​​the curing depth is slightly higher than at other content levels. Table 2 clearly shows that the curing depth of Experimental Example 1 is higher than that of the other examples and comparative examples.

[0060] Example 1 showed the best results when the magnesium dihydrogen phosphate addition was 7%, as this ratio produced sufficient magnesium oxide to generate magnesium aluminum spinel and improve performance, without producing excessive phosphorus oxide that would cause defects. Examples 2 and 3 reduced the content, resulting in insufficient magnesium aluminum spinel and failing to further improve performance; in Example 4, when the content reached 9%, residual phosphorus oxide appeared, leading to numerous defects and significantly reducing the performance of the AlN ceramic.

[0061] Comparative Example 1 did not have the addition of magnesium dihydrogen phosphate, so there was no improvement in curing depth during the printing stage, nor was magnesium aluminum spinel generated to improve performance. Comparative Examples 2, 3, and 4 had higher magnesium dihydrogen phosphate content, resulting in more residual phosphorus oxide, which, similar to Example 4, significantly reduced the performance of AlN ceramics.

[0062] In summary, the addition of 7% magnesium dihydrogen phosphate in this invention significantly improves the curing depth and mechanical and thermal properties of the photopolymerizable 3D printing AlN-based ceramic slurry. This is beneficial for printing AlN-based ceramic preforms for thermal management. Furthermore, this invention allows for flexible control of the powder system particle size through processes such as ball milling and sieving, combined with the rational selection of phosphate addition amounts, enabling the production of AlN ceramics with high mechanical and thermal properties.

[0063] The embodiments described above are some, but not all, of the embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for preparing phosphate-reinforced aluminum nitride ceramics based on photopolymerization 3D printing, characterized in that, Includes the following steps: S1. Prepare aluminum nitride photocurable slurry, wherein the aluminum nitride photocurable slurry comprises aluminum nitride powder, photocurable resin, phosphate, dispersant, photoinitiator, sintering aid and defoamer; S2. The above aluminum nitride photocurable slurry is photocured and printed. After degreasing, decarburizing and sintering, phosphate-reinforced aluminum nitride ceramics are obtained.

2. The preparation method according to claim 1, characterized in that, The phosphate is magnesium dihydrogen phosphate.

3. The preparation method according to claim 2, characterized in that, The amount of magnesium dihydrogen phosphate used is 3% to 9% of the sum of the weights of aluminum nitride powder and sintering aids.

4. The preparation method according to claim 1, characterized in that, The photocurable resin includes o-phenylphenoxyethyl acrylate, 1,6-hexanediol diacrylate, and ethoxylated pentaerythritol tetraacrylate; the dispersant includes a polymer copolymer dispersant; the photoinitiator includes bis(2,4,6-trimethylbenzoyl)diphenylphosphine oxide; and the sintering aid includes yttrium trioxide powder.

5. The preparation method according to claim 4, characterized in that, The mass ratio of o-phenylphenoxyethyl acrylate, 1,6-hexanediol diacrylate and ethoxylated pentaerythritol tetraacrylate is 5:4:

1.

6. The preparation method according to claim 1, characterized in that, The preparation method of the aluminum nitride photocurable slurry in step S1 includes: adding aluminum nitride powder, photocurable resin, phosphate, dispersant, photoinitiator and sintering aid to anhydrous ethanol and placing it in a ball mill jar, using zirconia ball milling beads as the ball milling medium, and ball milling and mixing for 9.5~10.5h.

7. The preparation method according to claim 1, characterized in that, In step S2, the photopolymerization printing parameters include: an exposure intensity of 19.38~32.81 mW / cm². 2 The printing layer thickness is 25μm; the exposure time is 5~15s; and aluminum nitride ceramic green bodies are obtained after layer-by-layer printing.

8. The preparation method according to claim 7, characterized in that, In step S2, the degreasing process includes: placing the photocured aluminum nitride ceramic green body in a protective atmosphere, raising the temperature from 25°C to 600°C at a rate of 0.1°C / min to 1°C / min, and holding it at 150°C, 250°C, 350°C and 450°C for 60 to 240 minutes respectively.

9. The preparation method according to claim 8, characterized in that, In step S2, the decarburization process includes: placing the degreased aluminum nitride ceramic in a muffle furnace, raising the temperature from 25°C to 1000°C at a rate of 0.5°C / min to 5°C / min, and holding it at 350°C and 600°C for 60 minutes respectively. The sintering process includes: placing the decarburized aluminum nitride ceramic in a protective atmosphere for pressureless sintering, first holding it at 1600℃ for 1 hour, and then holding it at 1850℃ for 3 hours.

10. A phosphate-reinforced aluminum nitride ceramic obtained by the preparation method according to any one of claims 1 to 9.

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