Preparation method of light-cured high-thermal-conductivity aluminum nitride ceramic special-shaped part based on synergistic regulation of residual carbon and yttrium fluoride

Abstract

This invention relates to a method for preparing photocurable high thermal conductivity aluminum nitride ceramic irregular parts based on the synergistic regulation of residual carbon and yttrium fluoride, comprising the following steps: S1, preparing a photocurable resin system; S2, adding aluminum nitride powder, yttrium fluoride, and a dispersant to the photocurable resin system to obtain a composite ceramic slurry suitable for photocurable 3D printing; S3, curing layer by layer to obtain an aluminum nitride ceramic irregular part green body; S4, placing the ceramic green body obtained in step S3 in an atmosphere sintering furnace for two-step debinding; S5, taking a small sample of the debinded sample obtained in step S4 for residual carbon content calibration; S6, sintering to obtain the aluminum nitride ceramic irregular part. This invention precisely controls the residual carbon content after debinding by designing photocurable monomer combinations with specific functionalities, and simultaneously uses yttrium fluoride sintering aid to achieve a triple effect of densification, removal of lattice oxygen, and absence of liquid phase residue. The residual carbon regulation and the synergistic effect of the aid complement each other to jointly achieve the preparation of high thermal conductivity aluminum nitride ceramic irregular parts.

Description

Technical Field

[0001] This invention relates to the fields of additive manufacturing and ceramic materials technology, and more specifically, to a method for preparing photocurable high thermal conductivity aluminum nitride ceramic irregular parts based on the synergistic regulation of residual carbon and yttrium fluoride. Background Technology

[0002] Photopolymer 3D printing technologies (including SLA and DLP) offer a revolutionary solution for fabricating complex aluminum nitride ceramic irregularly shaped parts, enabling "free manufacturing" without the need for expensive subsequent processing. However, the thermal conductivity of aluminum nitride ceramic irregularly shaped parts prepared by photopolymer 3D printing is generally low, with most studies reporting values ​​of only 150–180 W / m·K, significantly lower than the 230–250 W / m·K achievable by established industrial-scale forming processes such as dry pressing and tape casting. For high-power-density robot joints or irregularly shaped heat sinks for AI chips, this insufficient thermal conductivity leads to severe heat buildup, limiting the robot's sustained load capacity or the release of AI computing power. The main reasons for this gap include the following two aspects.

[0003] First, there is the issue of high organic content inherent in photopolymerization processes and the residual carbon problem during debinding. Photopolymerization requires the in-situ polymerization of photosensitive resin layer by layer under ultraviolet light, and the volume fraction of binder in ceramic slurry and green body is typically as high as 40–50 vol%. Debinding is a crucial step in removing organic matter: while air debinding can thoroughly remove carbon, the oxidizing atmosphere easily leads to oxidation of the aluminum nitride powder surface, introducing oxygen impurities, and the rapid exothermic oxidation can easily cause cracking of the green body; while inert atmosphere debinding can avoid oxidation, the pyrolysis of the resin will produce a large amount of residual carbon. Even with a stepwise debinding strategy of first inert atmosphere and then air atmosphere, a dilemma still exists: on the one hand, an appropriate amount of residual carbon can reduce oxygen in intergranular phases such as YAG during high-temperature sintering, promoting the removal of lattice oxygen and improving thermal conductivity; on the other hand, excessive residual carbon will remain at grain boundaries or form carbides, severely hindering phonon conduction and causing a significant decrease in thermal conductivity.

[0004] Second, the difference in the effectiveness of sintering aid systems in removing intergranular phases. To obtain high thermal conductivity aluminum nitride ceramic shaped parts, sintering aids are usually added to lower the sintering temperature and remove lattice oxygen. While traditional yttrium oxide sintering aids can form a YAG liquid phase to promote densification and possess a certain ability to remove lattice oxygen, the resulting liquid phase is often anchored between the grains, significantly affecting thermal conductivity. To obtain high thermal conductivity aluminum nitride, secondary sintering can effectively remove some intergranular phases, but this process often results in insufficient liquid phase removal, leading to low final product yield. In contrast, yttrium fluoride, as a sintering aid, has its final product discharged in gaseous form (such as volatile fluorides or hydrides) during sintering, with very little residue. However, when using YF3 alone, due to the low viscosity of the liquid phase during sintering and the weaker oxygen removal ability of YF3 compared to Y2O3, lattice oxygen removal is incomplete.

[0005] Therefore, overcoming the thermal conductivity bottleneck of photopolymer 3D printed aluminum nitride ceramic irregular parts is a key material technology to promote the high power density integration of robots, the upgrading of AI computing hardware thermal management, and the miniaturization of intelligent equipment. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing photocurable high thermal conductivity aluminum nitride ceramic irregular parts based on the synergistic regulation of residual carbon and yttrium fluoride. This method can solve the technical problem that the thermal conductivity of photocurable 3D printed aluminum nitride ceramic irregular parts is low due to the difficulty in controlling residual carbon after degreasing and the limited effect of sintering aids in removing intergranular phases.

[0007] The technical solution adopted by this invention to solve its technical problem is: a method for preparing photocurable high thermal conductivity aluminum nitride ceramic irregular parts based on the synergistic regulation of residual carbon and yttrium fluoride, comprising the following steps: S1. Prepare a photocurable resin system composed of low-functionality monomers and multifunctional monomers; S2. Add aluminum nitride powder with a solid content of 45-60 vol%, yttrium fluoride accounting for 3-8 wt% of the total mass of aluminum nitride powder, and dispersant accounting for 3%-5% of the total mass of aluminum nitride powder to the photocurable resin system in step S1. After mixing evenly, add photoinitiator and degas under vacuum to obtain a composite ceramic slurry suitable for photocurable 3D printing. S3. Place the composite ceramic slurry obtained in step S2 into a photopolymerization 3D printer and cure it layer by layer to obtain a green blank of aluminum nitride ceramic irregular part. S4. Place the ceramic green body obtained in step S3 into an atmosphere sintering furnace. The first degreasing heating rate is 0.1-0.5℃ / min, and the degreasing temperature is 400-800℃. The second degreasing heating rate is 0.2-1℃ / min, and the degreasing temperature is 400-600℃. S5. Take a small sample of the defatted sample obtained in step S4 to determine the residual carbon content and confirm that it is within the range of residual carbon content. S6. The degreased sample that is confirmed to be within the range of residual carbon content is sintered to obtain aluminum nitride ceramic irregular parts.

[0008] According to the above scheme, in step S1, the mass ratio of low-functionality monomer to multifunctionality monomer is (3-6):(6-3).

[0009] According to the above scheme, the low-functionality monomer includes difunctional monomers and monofunctional monomers, and the monofunctional monomer is one or more of isobornyl acrylate (IBOA), hydroxyethyl acrylate (HEA), and ethoxyethoxyethyl acrylate (EEEA).

[0010] According to the above scheme, the bifunctional monomer is 1,6-hexanediol diacrylate (HDDA) or triethylene glycol dimethacrylate (TEGDMA).

[0011] According to the above scheme, the multifunctional monomer is one or more of the following monomers: trimethylolpropane triacrylate (TMPTA), pentaerythritol triacrylate (PETA), ethoxylated pentaerythritol tetraacrylate (PPTTA), and dipentaerythritol hexaacrylate (DPHA).

[0012] According to the above scheme, in step S4, the first step of degreasing is carried out under nitrogen, argon or vacuum atmosphere.

[0013] According to the above scheme, in step S4, the second degreasing step is carried out under air.

[0014] According to the above scheme, in step S4, the first step of degreasing and heat preservation time is 2-6 hours, and the second step of degreasing and heat preservation time is 2-4 hours.

[0015] According to the above scheme, in step S5, the standard for residual carbon content is 0.8-2.5 wt%.

[0016] According to the above scheme, in step S6, sintering is carried out at 1700°C-1900°C under a nitrogen atmosphere, and the temperature is held for 2-8 hours. The furnace is then cooled to obtain aluminum nitride ceramic irregular parts with a thermal conductivity of 230-250 W / (m·K).

[0017] The method for preparing photocurable high thermal conductivity aluminum nitride ceramic irregular parts based on the synergistic regulation of residual carbon and yttrium fluoride of the present invention has the following beneficial effects: 1. This invention precisely controls the amount of residual carbon within a suitable range by combining low-functionality and multi-functionality monomers, thus avoiding damage to thermal conductivity caused by excessive residual carbon.

[0018] 2. This invention utilizes a dual mechanism of residual carbon regulation and synergistic effect with specific additives. By selecting yttrium fluoride as a sintering aid, clean grain boundaries are obtained. Simultaneously, an appropriate amount of residual carbon can reduce oxygen in intergranular phases such as YAG during sintering, promoting lattice oxygen removal and grain boundary purification. This solves the problem of weak oxygen removal capacity of yttrium fluoride as a single additive during sintering, resulting in aluminum nitride ceramic irregular parts with clean grain boundaries. The thermal conductivity of the prepared aluminum nitride ceramic irregular parts stably reaches 230-250 W / m·K, which is comparable to traditional processes such as dry pressing and tape casting. This invention completely breaks through the technical bottleneck that the thermal conductivity of photopolymer 3D printed aluminum nitride ceramic irregular parts has long hovered around 150-180 W / m·K.

[0019] 3. The present invention utilizes vacuum or atmosphere for the first step of degreasing to remove elements such as hydrogen and oxygen from the cured resin, leaving residual carbon, and then uses air atmosphere degreasing in the second step to remove a certain amount of residual carbon and control the content of residual carbon. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a comparison chart of the thermal conductivity of the aluminum nitride ceramic irregular parts prepared in Examples 1-2 and Comparative Examples 1-3; Figure 2 These are SEM images of the sintered aluminum nitride ceramic irregular-shaped parts prepared in Example 1; Figure 3 This is a SEM image of the sintered aluminum nitride ceramic irregular body prepared in Comparative Example 1 (Y2O3 additive); Figure 4 This is a SEM image of the sintered body of the aluminum nitride ceramic irregular part prepared in Comparative Example 2 (high residual carbon content); Figure 5 This is a graph showing the effect of different low-functionality / multifunctionality monomer ratios on the amount of residual carbon after degreasing. Detailed Implementation

[0021] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0022] This invention provides a method for preparing photocurable high thermal conductivity aluminum nitride ceramic irregular parts based on the synergistic regulation of residual carbon and sintering aids, comprising the following steps: Step 1: Prepare a photocurable resin system composed of low-functionality monomers or bifunctional monomers (one or more of isobornyl acrylate (IBOA), hydroxyethyl acrylate (HEA), ethoxyethoxyethyl acrylate (EEEA), 1,6-hexanediol diacrylate (HDDA), triethylene glycol dimethacrylate (TEGDMA)) and polyfunctional monomers (one or more of trifunctional or higher-functionality monomers such as trimethylolpropane triacrylate (TMPTA), pentaerythritol triacrylate (PETA), ethoxylated pentaerythritol tetraacrylate (PPTTA), dipentaerythritol hexaacrylate (DPHA)). The mass ratio of low-functionality monomers to polyfunctional monomers is (3-6):(6-3). By adjusting this ratio, low-functionality monomers, with their smaller molecular weight, are easier to thermally decompose, while polyfunctional monomers, with their larger molecular weight, are more difficult to thermally decompose. Therefore, when using the same heat treatment process, the resin formulation with a higher content of low-functionality monomers has a lower residual carbon content (as low as 0.8%). Resin formulations with high levels of functional monomers have high carbon residue (up to 2.5 wt%), while those with high levels of functional monomers have high carbon residue (up to 2.5 wt%).

[0023] Step 2: Add aluminum nitride powder with a solid content of 45-60 vol%, yttrium fluoride accounting for 3-8 wt% of the total mass of aluminum nitride powder, and dispersant accounting for 3%-5% of the total mass of aluminum nitride powder to the photocurable resin system obtained in Step 1. After mixing evenly, add photoinitiator and degas under vacuum to obtain a composite ceramic slurry suitable for photocurable 3D printing.

[0024] Step 3: Place the composite ceramic slurry obtained in Step 2 into a photopolymerization 3D printer, and use slicing software to control ultraviolet light irradiation to cure layer by layer to obtain a green body of aluminum nitride ceramic irregular part.

[0025] Step 4: Place the ceramic green body obtained in Step 3 into an atmosphere sintering furnace. The first step is carried out under nitrogen, argon, or vacuum atmosphere, with a heating rate of 0.1-0.5℃ / min, a degreasing temperature of 400-800℃, and a holding time of 2-6 hours. The second step is carried out under air atmosphere, with a heating rate of 0.2-1℃ / min, a degreasing temperature of 400-600℃, and a holding time of 2-4 hours. With the same resin formulation, the second step with higher air degreasing temperature results in a relatively lower residual carbon content, and a longer holding time also leads to a relatively lower residual carbon content. Conversely, the second step with lower air degreasing temperature results in a relatively higher residual carbon content, and a shorter holding time also leads to an increased residual carbon content.

[0026] Step 5: Take a small sample of the degreased sample obtained in Step 4 and calibrate the residual carbon content to confirm that it is within the range of 0.8-2.5wt% residual carbon content.

[0027] Step 6: Sinter at 1700°C-1900°C under a nitrogen atmosphere, hold for 2-8 hours, and cool with the furnace to obtain a thermal conductivity of 230-250 W / (m²). Aluminum nitride ceramic irregular parts.

[0028] Experimental materials: Aluminum nitride powder: D50=1.2μm, purity ≥99.5%; Yttrium oxide (Y2O3) powder: D50=0.5μm, purity ≥99.9%; Yttrium fluoride (YF3) powder: D50 = 0.5 μm, purity ≥ 99.9%; Low-functionality monomers: HDDA, TEGDMA (bifunctional), IBOA, HEA, EEEA (monofunctional); Multifunctional monomers: TMPTA (trifunctional), PPTTA (tetrafunctional), DPHA (hexafunctional); Dispersant: BYK-111 (phosphate ester polymer); Photoinitiator: TPO (2,4,6-trimethylbenzoyl-diphenylphosphine oxide).

[0029] Test method: Residual carbon content test of resin and slurry: Thermogravimetric analyzer (TGA), N2 atmosphere, heating rate 10℃ / min, test up to 1000℃; Test of residual carbon content in degreased green body: carbon-sulfur analyzer; Thermal conductivity testing: Laser flare method (LFA), room temperature test; Microstructure: Fracture morphology was observed using a scanning electron microscope (SEM); Density: Archimedes' method of water displacement.

[0030] Example 1 (high proportion of monofunctional components and low proportion of high-functional components, high air degreasing temperature, relatively low carbon content, yttrium polyfluoride) (1) Design of photocurable resin system: The monofunctional monomer IBOA, the difunctional HDDA and the multifunctional monomer TMPTA are mixed in a mass ratio of 1:1:1 to obtain the photocurable resin system.

[0031] (2) Preparation of composite slurry: Take 100g of AlN powder, 6g of yttrium fluoride powder, 2g of dispersant BYK-1112g, and 40g of the photocurable resin system obtained in step (1). Mix them for 4h using a planetary ball mill, then add 1g of photoinitiator TPO, continue mixing for 1h, and vacuum degas for 20min to obtain composite ceramic slurry (solid content 52vol%).

[0032] (3) Photopolymerization 3D printing: Pour the slurry into the DLP photopolymerization printer, with a layer thickness of 50μm and an exposure time of 8s, and print to obtain a ceramic green body.

[0033] (4) Degreasing and sintering: The green blank is placed in an atmosphere sintering furnace and heated to 550°C at 0.3°C / min under N2 atmosphere and held for 2 hours for degreasing. Then, it is heated to 600°C at 0.8°C / min under air atmosphere and held for 2 hours. (5) Residual carbon calibration: The residual carbon content of the degreased green body is tested using a carbon-sulfur analyzer.

[0034] (6) Sintering: The temperature is increased to 1780℃ at 3℃ / min under N2 atmosphere, and sintered for 3h. The furnace is then cooled to obtain a high thermal conductivity aluminum nitride ceramic part with clean grain boundaries.

[0035] Example 2 (high proportion of single-functional components and low proportion of high-functional components, low air degreasing temperature, relatively medium carbon content, and medium yttrium fluoride content) (1) Design of photocurable resin system: The monofunctional monomer IBOA, the difunctional HDDA and the multifunctional monomer TMPTA are mixed in a mass ratio of 1:1:1 to obtain the photocurable resin system.

[0036] (2) Preparation of composite slurry: Take 100g of AlN powder, 4.5g of yttrium fluoride powder, 2g of dispersant BYK-1112, and 40g of the photocurable resin system obtained in step (1). Mix them for 4 hours using a planetary ball mill, then add 1g of photoinitiator TPO, continue mixing for 1 hour, and vacuum degas for 20 minutes to obtain composite ceramic slurry (solid content 52 vol%).

[0037] (3) Photopolymerization 3D printing: Pour the slurry into the DLP photopolymerization printer, with a layer thickness of 50μm and an exposure time of 8s, and print to obtain a ceramic green body.

[0038] (4) Degreasing and sintering: The green blank is placed in an atmosphere sintering furnace and heated to 600°C at 0.5°C / min under N2 atmosphere and held for 3 hours to degrease. Then, it is heated to 500°C at 1°C / min under air atmosphere and held for 2 hours. (5) Residual carbon calibration: The residual carbon content of the degreased green body is tested using a carbon-sulfur analyzer.

[0039] (6) Sintering: The temperature is increased to 1780℃ at 3℃ / min under N2 atmosphere, and sintered for 3h. The furnace is then cooled to obtain a high thermal conductivity aluminum nitride ceramic part with clean grain boundaries.

[0040] Example 3 (low monofunctionality, high monofunctionality, high air degreasing temperature, relatively medium carbon content, and medium yttrium fluoride content) (1) Design of photocurable resin system: The monofunctional monomer HEA, the difunctional TEGDMA and the multifunctional monomer PPTTA are mixed in a mass ratio of 1:2:6 to obtain the photocurable resin system.

[0041] (2) Preparation of composite slurry: Take 100g of AlN powder, 4.5g of yttrium fluoride powder, 2g of dispersant BYK-1112, and 40g of the photocurable resin system obtained in step (1). Mix them for 4 hours using a planetary ball mill, then add 1g of photoinitiator TPO, continue mixing for 1 hour, and vacuum degas for 20 minutes to obtain composite ceramic slurry (solid content 52 vol%).

[0042] (3) Photopolymerization 3D printing: Pour the slurry into the DLP photopolymerization printer, with a layer thickness of 45μm and an exposure time of 8s, and print to obtain a ceramic green body.

[0043] (4) Degreasing and sintering: The green blank is placed in an atmosphere sintering furnace and heated to 550°C at 0.3°C / min under N2 atmosphere and held for 2 hours for degreasing. Then, it is heated to 600°C at 0.8°C / min under air atmosphere and held for 2 hours. (5) Residual carbon calibration: The residual carbon content of the degreased green body is tested using a carbon-sulfur analyzer.

[0044] (6) Sintering: Under N2 atmosphere, the temperature is increased to 1800℃ at 5℃ / min, held for 4h for sintering, and cooled with the furnace to obtain a high thermal conductivity aluminum nitride ceramic shaped part with clean grain boundaries.

[0045] Example 4 (low monofunctional ratio, high high-functional ratio, low air degreasing temperature, relatively high carbon content, low yttrium fluoride content) (1) Design of photocurable resin system: The monofunctional monomer HEA, the difunctional TEGDMA and the multifunctional monomer PPTTA are mixed in a mass ratio of 1:2:6 to obtain the photocurable resin system.

[0046] (2) Preparation of composite slurry: Take 100g of AlN powder, 3g of yttrium fluoride powder, 2g of dispersant BYK-1112g, and 40g of the photocurable resin system obtained in step (1). Mix them for 4h using a planetary ball mill, then add 1g of photoinitiator TPO, continue mixing for 1h, and vacuum degas for 20min to obtain composite ceramic slurry (solid content 52vol%).

[0047] (3) Photopolymerization 3D printing: Pour the slurry into the DLP photopolymerization printer, with a layer thickness of 45μm and an exposure time of 8s, and print to obtain a ceramic green body.

[0048] (4) Degreasing and sintering: The green blank is placed in an atmosphere sintering furnace and heated to 600°C at 0.5°C / min under N2 atmosphere and held for 3 hours to degrease. Then, it is heated to 500°C at 1°C / min under air atmosphere and held for 2 hours. (5) Residual carbon calibration: The residual carbon content of the degreased green body is tested using a carbon-sulfur analyzer.

[0049] (6) Sintering: Under N2 atmosphere, the temperature is increased to 1800℃ at 5℃ / min, held for 4h for sintering, and cooled with the furnace to obtain a high thermal conductivity aluminum nitride ceramic shaped part with clean grain boundaries.

[0050] Example 5 (Controlling residual carbon with different monomer ratios) (1) Design of photocurable resin system: The monofunctional monomer IBOA, the difunctional monomer HDDA and the multifunctional monomer DPHA were mixed at mass ratios of 4:4:2, 3:3:3, 2:3:5, 1:2:6 and 1:1:8 respectively to obtain 5 photocurable resin systems with different residual carbon content.

[0051] The remaining steps are the same as in Example 1.

[0052] Comparative Example 1 (Another sintering aid) (1) Design of the photocurable resin system: Same as in Example 1 (IBOA:HDDA:TMPTA=1:1:1).

[0053] (2) Sintering aid system: Only Y2O3 is used, and the amount added is 3wt% of the mass of AlN powder (excluding YF3).

[0054] The remaining steps are the same as in Example 1.

[0055] Comparative Example 2 (High Residual Carbon Content) (1) Design of photocurable resin system: Only multifunctional monomer TMPTA is used (the content of low-functional monomer is 0).

[0056] The remaining steps are the same as in Example 1.

[0057] Comparative Example 3 (Low Residual Carbon Content) (1) Design of photocurable resin system: Only monofunctional monomers IBOA:HDDA=1:1 are used (the content of multifunctional monomers is 0).

[0058] The remaining steps are the same as in Example 1.

[0059] Example 6 (Effect of monomer ratio on residual carbon content) TGA tests were performed on the five resin systems with different monomer ratios in Example 5 to test their residual carbon rate (percentage relative to the initial mass of the resin) after degreasing at 600°C under N2 atmosphere, and converted to residual carbon amount relative to the mass of AlN powder (calculated based on the mass ratio of resin to powder in the slurry). The results are shown in Table 1.

[0060] Table 1. Effect of different HDDA / TMPTA ratios on residual carbon content

[0061] The results showed that the residual carbon content of the resin increased significantly with the increase of the proportion of the multifunctional monomer DPHA. By adjusting the ratio of low-functionality to multifunctional monomers, the residual carbon content can be precisely controlled within the range of 0.8-2.5 wt%.

[0062] Example 7 (Performance Test Results) The performance of the aluminum nitride ceramic irregular parts prepared in Examples 1-4 and Comparative Examples 1-3 was tested, and the results are shown in Table 2.

[0063] Table 2 Comparison of ceramic properties of different embodiments and comparative examples

[0064] Please refer to Table 1 and Table 2. Figures 1-5 The specific technical effects are analyzed as follows: (1) An optimal range exists for residual carbon content: The thermal conductivity of Example 1 (residual carbon 0.81%), Example 2 (residual carbon 2.49%), Comparative Example 2 (residual carbon 6.5%), and Comparative Example 3 (residual carbon 0.1%) are 242, 240, 152, and 168 W / m², respectively. This indicates that if the residual carbon content is too low (<0.8%), the deoxygenation capacity is insufficient, and if the residual carbon content is too high (>2.5%), the thermal conductivity will be severely impaired. The optimal residual carbon range is 0.8-2.5 wt%.

[0065] (2) Significant synergistic effect of yttrium fluoride and residual carbon: compared with Example 1 (242 W / ) and Comparative Example 1 (178 W / Both had the same residual carbon content (0.81%), but Example 1 used YF3 additive, which increased the thermal conductivity by approximately 70 W / m² compared to Comparative Example 1 (Y₂O₃). This fully demonstrates that under this scheme, carbon compensates for the insufficient oxygen removal capacity of yttrium fluoride, while the low residue at yttrium fluoride grain boundaries significantly improves the performance of the final product. Examples 1 and 2 simultaneously achieved optimal residual carbon content (0.8-2.5%) and synergistic effects with additives, with thermal conductivity exceeding 240 W / m². The achievement of industrialization demonstrates that the dual mechanism of "residual carbon regulation + yttrium fluoride synergy" has a significant synergistic effect.

[0066] (3) The residual carbon content was significantly controlled by the degreasing temperature: Comparing Example 1 (600℃ degreasing, low carbon) and Example 2 (500℃ degreasing, medium carbon), the residual carbon content was 0.81% and 1.34% respectively under the same resin formulation, and the thermal conductivity was 242 and 239 W / m·K respectively; under another resin formulation in Example 3 (600℃ degreasing, medium carbon) and Example 4 (500℃ high carbon), the residual carbon content was 1.85% and 2.49% respectively, and the thermal conductivity was 241 and 240 W / m·K respectively. This shows that increasing the air degreasing temperature can effectively reduce the residual carbon content, while decreasing the temperature increases the residual carbon content. However, regardless of the residual carbon content fluctuating within the range of 0.81-2.49 wt%, as long as it is within the optimal range of 0.8-2.5 wt% and synergistic with yttrium fluoride, the thermal conductivity can stably reach above 239 W / m·K, proving the effectiveness and process tolerance of degreasing temperature as an independent control parameter.

[0067] This invention precisely controls the amount of residual carbon after degreasing by designing a specific combination of photocurable monomers with specific functionalities, thus aiding in the removal of some lattice oxygen. Simultaneously, it employs yttrium fluoride sintering aids to achieve a triple effect of densification, removal of lattice oxygen, and elimination of liquid phase residue. The control of residual carbon and the synergistic effect of the aids complement each other, jointly enabling the fabrication of high thermal conductivity aluminum nitride ceramic irregularly shaped parts. This allows for the industrialization of photocurable 3D-printed aluminum nitride ceramic irregularly shaped parts with a thermal conductivity of 230-250 W / m·K.

[0068] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for preparing photocurable high thermal conductivity aluminum nitride ceramic irregular parts based on the synergistic regulation of residual carbon and yttrium fluoride, characterized in that, Includes the following steps: S1. Prepare a photocurable resin system composed of low-functionality monomers and multifunctional monomers; S2. Add aluminum nitride powder with a solid content of 45-60 vol%, yttrium fluoride accounting for 3-8 wt% of the total mass of aluminum nitride powder, and dispersant accounting for 3%-5% of the total mass of aluminum nitride powder to the photocurable resin system in step S1. After mixing evenly, add photoinitiator and degas under vacuum to obtain a composite ceramic slurry suitable for photocurable 3D printing. S3. Place the composite ceramic slurry obtained in step S2 into a photopolymerization 3D printer and cure it layer by layer to obtain a green blank of aluminum nitride ceramic irregular part. S4. Place the ceramic green body obtained in step S3 into an atmosphere sintering furnace. The first degreasing heating rate is 0.1-0.5℃ / min, and the degreasing temperature is 400-800℃. The second degreasing heating rate is 0.2-1℃ / min, and the degreasing temperature is 400-600℃. S5. Take a small sample of the defatted sample obtained in step S4 to determine the residual carbon content and confirm that it is within the range of residual carbon content. S6. The degreased sample that is confirmed to be within the range of residual carbon content is sintered to obtain aluminum nitride ceramic irregular parts.

2. The method for preparing photocurable high thermal conductivity aluminum nitride ceramic irregular parts based on the synergistic regulation of residual carbon and yttrium fluoride according to claim 1, characterized in that, In step S1, the mass ratio of low-functionality monomer to multifunctionality monomer is (3-6):(6-3).

3. The method for preparing photocurable high thermal conductivity aluminum nitride ceramic irregular parts based on the synergistic regulation of residual carbon and yttrium fluoride according to claim 1, characterized in that, The low-functionality monomers include difunctional monomers and monofunctional monomers, wherein the monofunctional monomers are one or more of isobornyl acrylate (IBOA), hydroxyethyl acrylate (HEA), and ethoxyethoxyethyl acrylate (EEEA).

4. The method for preparing photocurable high thermal conductivity aluminum nitride ceramic irregular parts based on the synergistic regulation of residual carbon and yttrium fluoride according to claim 3, characterized in that, The bifunctional monomer is 1,6-hexanediol diacrylate (HDDA) or triethylene glycol dimethacrylate (TEGDMA).

5. The method for preparing photocurable high thermal conductivity aluminum nitride ceramic irregular parts based on the synergistic regulation of residual carbon and yttrium fluoride according to claim 1, characterized in that, The multifunctional monomer is one or more of the following monomers: trimethylolpropane triacrylate (TMPTA), pentaerythritol triacrylate (PETA), ethoxylated pentaerythritol tetraacrylate (PPTTA), and dipentaerythritol hexaacrylate (DPHA).

6. The method for preparing photocurable high thermal conductivity aluminum nitride ceramic irregular parts based on the synergistic regulation of residual carbon and yttrium fluoride according to claim 1, characterized in that, In step S4, the first degreasing step is carried out under a nitrogen, argon, or vacuum atmosphere.

7. The method for preparing photocurable high thermal conductivity aluminum nitride ceramic irregular parts based on the synergistic regulation of residual carbon and yttrium fluoride according to claim 1, characterized in that, In step S4, the second degreasing step is carried out under air.

8. The method for preparing photocurable high thermal conductivity aluminum nitride ceramic irregular parts based on the synergistic regulation of residual carbon and yttrium fluoride according to claim 1, characterized in that, In step S4, the first step of degreasing and heat preservation time is 2-6 hours, and the second step of degreasing and heat preservation time is 2-4 hours.

9. The method for preparing photocurable high thermal conductivity aluminum nitride ceramic irregular parts based on the synergistic regulation of residual carbon and yttrium fluoride according to claim 1, characterized in that, In step S5, the standard for residual carbon content is 0.8-2.5 wt%.

10. The method for preparing photocurable high thermal conductivity aluminum nitride ceramic irregular parts based on the synergistic regulation of residual carbon and yttrium fluoride according to claim 1, characterized in that, In step S6, sintering is carried out at 1700°C-1900°C under a nitrogen atmosphere, held for 2-8 hours, and then cooled in the furnace to obtain aluminum nitride ceramic irregular parts with a thermal conductivity of 230-250 W / (m·K).

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