High-performance ceramic ultra-fast degreasing and sintering method based on photocuring additive manufacturing

Abstract

The invention discloses a high-performance ceramic ultra-fast degreasing and sintering method based on photocuring additive manufacturing, and relates to the technical field of photocuring additive manufacturing. The method comprises the following steps: preparing a monomer containing chemical functional groups for photo-crosslinking reaction and thermal crosslinking reaction or high polymer photo-cured ceramic slurry with high solid phase content; carrying out photocuring molding to obtain a printing green body; and the printing green body is subjected to ultra-fast degreasing and ultra-fast high-temperature sintering through ultra-fast high-temperature sintering equipment based on Joule heating. According to the invention, a monomer or high polymer system with photo-crosslinking and thermal crosslinking dual-mechanism reactions is introduced, and a polymer network skeleton with high strength and high decomposition rate is constructed in a printing green body. According to the slurry system, the green body can bear an extremely high temperature rise rate without cracking, deformation or bubbling in Joule heating ultra-fast high-temperature sintering equipment, so that organic matters are quickly and thoroughly removed, and the degreasing efficiency and reliability are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of photopolymer additive manufacturing technology, and in particular to a method for ultra-fast debinding and sintering of high-performance ceramics based on photopolymer additive manufacturing. Background Technology

[0002] High-performance ceramics (also known as special ceramics, fine ceramics, or high-tech ceramics) are a new type of advanced material that, due to their excellent physical, chemical, and mechanical properties, have shown broad application potential in high-end fields such as aerospace, electronics, and biomedicine. Based on high-purity raw materials and precise manufacturing processes, these materials are significantly different from traditional ceramics and can be classified according to functional requirements into structural ceramics (such as oxides, nitrides, carbides, high-entropy, and transparent ceramics) and functional ceramics (including piezoelectric, ferroelectric, dielectric, and sensitive ceramics). Furthermore, bioceramics, smart ceramics, and ceramic matrix composites have further expanded their application scope.

[0003] Among various manufacturing processes for high-performance ceramics, photopolymer additive manufacturing technology has attracted much attention due to its high precision, high efficiency, and ability to form complex structures. This technology forms a green body by layer-by-layer curing of photosensitive slurry, followed by debinding and sintering to obtain dense ceramic parts. However, the organic components in the green body need to be removed by a thermal debinding process, which typically requires staged holding at an extremely slow heating rate (e.g., 0.3–1.5℃ / min) within the range of 80–600℃ to allow the organic matter to decompose gradually. This process often takes tens or even hundreds of hours, severely limiting the overall manufacturing efficiency.

[0004] Besides debinding, the sintering process also has a crucial impact on the final properties of ceramics. Different sintering methods (such as pressureless sintering, hot pressing, and spark plasma sintering) significantly alter the diffusion mechanism, mass transfer behavior, and microstructure of materials, thereby affecting their thermal and mechanical properties. Although emerging technologies such as ultrafast high-temperature sintering (UHS) can achieve densification within minutes, significantly reducing energy consumption and suppressing grain growth, most current sintering methods still require tens of minutes to tens of hours, and have not yet fully realized their energy-saving potential.

[0005] Existing patented technologies also reflect similar bottlenecks. For example, the zirconia ceramics reported in CN116854468B require a degreasing and sintering process involving multiple slow heating stages and long holding times; CN118420353A and CN119661234A respectively proposed complex multi-stage degreasing procedures and sintering curves for aluminum nitride ceramics, which still require processing times of more than ten hours; while CN105330268B, although shortening the total time to 8–20 hours through a two-step degreasing method, still failed to fundamentally solve the problem of low efficiency.

[0006] Therefore, although photopolymer additive manufacturing technology provides a good foundation for the formation of complex structures in high-performance ceramics, the long debinding and sintering processes currently severely limit the overall efficiency and widespread application of this technology. There is an urgent need to develop a new process method that can significantly shorten the debinding and sintering time while ensuring material properties, thereby improving the feasibility and economy of photopolymer additive manufacturing of high-performance ceramics. Summary of the Invention

[0007] The technical problem to be solved by this invention is that the debinding and sintering process of high-performance ceramics prepared by photopolymer additive manufacturing technology is relatively long. This invention provides an ultra-fast debinding and sintering method for high-performance ceramics based on photopolymer additive manufacturing.

[0008] To address the above problems, the present invention proposes the following technical solution:

[0009] This invention provides a method for ultra-fast debinding and sintering of high-performance ceramics based on photopolymer additive manufacturing, comprising the following steps:

[0010] A high-solid-content photocurable ceramic slurry is prepared, wherein the photocurable ceramic slurry contains:

[0011] (a) at least one monomer or polymer with a chemical functional group capable of photocrosslinking reaction, 1 to 20 wt%;

[0012] (b) At least one monomer or polymer with a chemical functional group capable of thermal crosslinking reaction, 0.5 to 5 wt%;

[0013] (c) at least one low molecular weight solvent, 8.5 to 39 wt%;

[0014] (d) High-performance ceramic powder, 60–90 wt%;

[0015] (e) At least one photoinitiator, comprising 0.5 to 5 wt% of a monomer or polymer with chemical functional groups capable of photocrosslinking;

[0016] Photopolymerization molding is performed to obtain the printed green body;

[0017] The ultra-fast high-temperature sintering equipment based on Joule heating performs ultra-fast degreasing and ultra-fast high-temperature sintering on the printed green body.

[0018] The photocurable ceramic slurry of the present invention has a solid content of 30-70 vol%, preferably 45-65 vol%. During the photocuring process, the slurry undergoes a photocuring crosslinking reaction at low temperature using monomers or polymers with chemical functional groups capable of photocrosslinking, resulting in a printed green body. During the debinding process, this printed green body undergoes a thermal crosslinking reaction at high temperature using monomers or polymers (b) with chemical functional groups capable of thermal crosslinking. This thermal crosslinking reaction significantly improves the interparticle adhesion and body strength of the green body during debinding, thereby preventing cracking and deformation.

[0019] Furthermore, the photocuring crosslinking reaction temperature of the monomer or polymer of the chemical functional group capable of photocrosslinking is 0–60°C, preferably 20–30°C.

[0020] According to the present invention, the preferred monomer (a) containing chemical functional groups capable of photocrosslinking reaction includes at least one (meth)acrylate, (meth)acrylamide, thiol-containing acrylic resin, acrylic group-modified organosilicon resin or mixture thereof, particularly preferred are multifunctional (meth)acrylate, acrylic group-modified organosilicon polymer or mixture thereof.

[0021] Suitable examples of polyfunctional (meth)acrylates are pentaerythritol tetraacrylate (PPTTA), bisphenol A di(meth)acrylate, ethoxylated or propoxylated bisphenol A di(meth)acrylate, di, tri, tetra, penta, hexa or heptapropylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate.

[0022] Tetra-, penta-, and hexa-functional acrylates, methacrylates, and organosilicon polymers are particularly preferred, such as dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, and acrylic acid-modified organosilicon polymers. These highly functional monomers or polymers have more photoreactive groups, which helps to improve the strength of the green body and ensure the integrity of the green body during the degreasing process.

[0023] Furthermore, the thermal crosslinking reaction temperature of the monomer or polymer of the chemical functional group capable of thermal crosslinking is 40–300°C, preferably 80–250°C.

[0024] Furthermore, the monomers or polymers with chemical functional groups capable of thermal crosslinking are selected from at least one secondary, primary, and tertiary amine monomer or polymer. These polymers exhibit thermosetting properties, high-temperature stability, and high adhesion, and can be re-crosslinked with acrylic or epoxy groups by means of heat during photocrosslinking or degreasing, thereby improving the strength of the preform. Suitable compounds include methylamine, urea, ethylamine, ethanolamine, ethylenediamine, dimethylamine, trimethylamine, triethylamine, propylamine, isopropylamine, 1,3-propanediamine, 1,2-propanediamine, tripropylamine, triethanolamine, butylamine, isobutylamine, tert-butylamine, hexylamine, octylamine, aniline, benzylamine, cyclohexylamine, pyridine, hexamethylenetetramine, o-toluidine, m-toluidine, p-toluidine, 8-hydroxyquinoline, diphenylamine, and benzidine. Polymers containing secondary, primary, and tertiary amines are also suitable, such as polyethyleneimine, polyimide, polydopamine, polyurea, and polyacrylamide. Polyethyleneimine and polyimide are particularly suitable.

[0025] Furthermore, the photocurable ceramic slurry also includes a surface modifier. The surface modifier and the monomer or polymer of the chemical functional group that can realize the thermal crosslinking reaction are premixed with the high-performance ceramic powder to modify the surface of the high-performance ceramic powder. Then, the monomer or polymer of the chemical functional group that can realize the photocrosslinking reaction and the low molecular weight solvent are added to prepare the photocurable ceramic slurry.

[0026] This invention introduces monomers or polymers (b) with chemically functional groups capable of thermal crosslinking reactions into the surface of structural ceramics as surface modifiers. This surface modification method can more effectively improve the strength of the green body during the debinding process. These monomers or polymers (b) with chemically functional groups capable of thermal crosslinking reactions can be compounded with reagents such as oleic acid, carboxylic acid, phosphoric acid, or silane coupling agents, which are beneficial for improving the compatibility of powder and resin, and are also beneficial for reducing slurry viscosity.

[0027] According to the present invention, the low molecular weight solvent (c) has the characteristic of low boiling point. Reagents with boiling points in the range of 60°C to 300°C are preferred. Reagents with boiling points in the range of 150°C to 250°C are particularly preferred. The low molecular weight solvent (c) has the advantage of low molecular polarity, which can avoid the entanglement of chemical monomers, significantly reduce slurry viscosity, and increase the solid phase content. During the degreasing process, these low molecular weight solvents preferentially detach from the green body, easily flow out in liquid form, and quickly form airflow channels, thereby promoting rapid degreasing and avoiding damage to the green body.

[0028] Furthermore, the low molecular weight solvent is selected from terpineol, polyethylene glycol, water, ethanol, toluene, tetrahydrofuran, mixtures thereof, and modifiers.

[0029] According to the present invention, the high-performance ceramic powders include, but are not limited to, nitride ceramics (aluminum nitride, silicon nitride, etc.), oxide ceramics (zirconia, alumina, etc.), carbide ceramics (silicon carbide, titanium carbide, etc.), piezoelectric ceramics, high-entropy ceramics, transparent ceramics, and the above-mentioned ceramic matrix composites. Granulation, spheroidization, and gradation treatment of these powders are preferred, as this can significantly increase the solid content of the slurry and improve its flowability.

[0030] According to the present invention, the photopolymerization molding method of the slurry includes, but is not limited to, stereolithography (SLA), digital light processing (DLP), and two-photon polymerization (TPP).

[0031] This invention relates to an ultra-fast high-temperature sintering apparatus based on Joule heating for ultra-fast degreasing and ultra-fast high-temperature sintering of the printed green body. Typically, the ultra-fast high-temperature sintering apparatus includes:

[0032] (1) A carbon-based porous liquid-absorbing sheet, felt, or powder;

[0033] (2) A controllable power supply and positive and negative electrodes;

[0034] (3) A glass box capable of providing air, inert atmosphere, and vacuum atmosphere, and a corresponding cooling system;

[0035] (4) Infrared thermometer and thermocouple temperature measuring device.

[0036] In this device, the left and right ends of a porous carbon-based absorbent sheet, felt, or powder (1) are connected to the positive and negative electrodes (2) of a controllable power supply, and the electrical energy output by the controllable power supply can achieve Joule heating. This controllable power supply can output constant power or pulse power at a certain frequency, thereby generating precisely controllable temperature heat or pulse heat on the porous carbon absorbent felt (1). This heating device can achieve a heating rate of up to 1000℃ / s.

[0037] During the degreasing process, the high temperature generated by the carbon-based porous absorbent sheets, felts, or powder (1) allows the solvent in the green body to preferentially decompose and flow out of the green body, and is drawn into the porous absorbent carbon felt (1) through the porous wicking effect, preventing the accumulation of organic matter inside the green body, thereby improving the degreasing efficiency and preventing the green body from cracking. In further heating, the solvent in the carbon-based porous absorbent sheets, felts, or powder (1) will evaporate and leave the carbon-based porous absorbent sheets, felts, or powder (1). More importantly, this Joule-based ultra-fast high-temperature sintering equipment has controllable high temperature and ultra-fast heating rate, so that the organic matter is rapidly pyrolyzed and flows out of the green body, so that the green body does not contain too much residual carbon and does not require further air degreasing. Therefore, it can directly enter the sintering stage.

[0038] According to the present invention, the appropriate degreasing atmosphere and sintering atmosphere are determined based on the TG-DSC curves of the printed green body in air, nitrogen, hydrogen, argon, and their mixtures or vacuum atmosphere. Vacuum atmosphere is preferred for degreasing, as it is more conducive to the removal of organic matter.

[0039] Furthermore, the heating rate of the ultra-fast degreasing is 10-100℃ / min, and the degreasing holding temperature of the slurry of different ceramic systems can be determined by thermogravimetric-differential scanning calorimetry test, with a holding time of 5 seconds to 180 minutes, preferably 20 seconds to 90 minutes.

[0040] Furthermore, the heating rate of the ultra-fast high-temperature sintering is not less than 200℃ / min, and the holding time is from 1 second to 60 min.

[0041] The present invention also provides a method for preparing high-performance ceramics, including the ultra-fast debinding and sintering method for high-performance ceramics based on photocuring additive manufacturing.

[0042] The present invention also provides a high-performance ceramic, which is prepared by the method described above.

[0043] Compared with the prior art, the technical effects achieved by the present invention include:

[0044] This invention provides a high-performance ceramic ultra-fast debinding and sintering method based on photopolymer additive manufacturing. By introducing a monomer or polymer system with both photocrosslinking and thermal crosslinking mechanisms, and in conjunction with the synergistic effect of a low molecular weight solvent, a high-strength, high-decomposition-rate polymer network framework is constructed inside the printed green body. This slurry system enables the green body to withstand extremely high heating rates in a Joule-heated ultra-fast high-temperature sintering device without cracking, deformation, or blistering, thereby achieving rapid and thorough removal of organic matter. This significantly shortens the traditional thermal debinding process, which requires tens or even hundreds of hours, to within minutes, significantly improving debinding efficiency and reliability.

[0045] Meanwhile, this invention utilizes the ultra-high-speed heating and high-temperature field uniformity unique to Joule heating technology, allowing for immediate transition to the ultra-fast sintering stage after debinding. The extremely high heating rate effectively suppresses abnormal grain growth in ceramics, promoting uniform densification of the green body, thereby obtaining high-performance ceramic parts with fine grains, dense structure, and excellent mechanical properties. This sintering method not only avoids the volatilization of grain boundary phases or compositional segregation that may result from traditional long-term sintering, but also facilitates obtaining superior thermal, mechanical, and functional properties.

[0046] In summary, this invention combines innovative material formulations with ultra-fast process equipment, fundamentally solving the core technical bottleneck of long debinding and sintering cycles in the process of photopolymer additive manufacturing of high-performance ceramics. It achieves a qualitative leap in the overall manufacturing efficiency from green body to dense part, while ensuring the optimization and improvement of the comprehensive performance of the final ceramic part. Attached Figure Description

[0047] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 The rheological curves of the slurry in Example 1 and Comparative Example 1 are shown.

[0049] Figure 2 The figures are top views of the degreased blanks of Examples 2-3 and Comparative Examples 2-3; in the figures, (a) is the degreased blank of Comparative Example 2, (b) is the degreased blank of Comparative Example 3, (c) is the degreased blank of Example 2 after heating to 550°C at a rate of 20°C / min, and (d) is the degreased blank of Example 3 after heating to 550°C at a rate of 30°C / min.

[0050] Figure 3 for Figure 2 Side view.

[0051] Figure 4 The figures show cross-sectional SEM images of aluminum nitride ceramic samples obtained in Examples 4-9; in the figures, (a) is a cross-sectional SEM image of the ceramic sample of Example 4; (b) is a cross-sectional SEM image of the ceramic sample of Example 5; (c) is a cross-sectional SEM image of the ceramic sample of Example 6; (d) is a cross-sectional SEM image of the ceramic sample of Example 7; (e) is a cross-sectional SEM image of the ceramic sample of Example 8; and (f) is a cross-sectional SEM image of the ceramic sample of Example 9. Detailed Implementation

[0052] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0053] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0054] It should also be understood that the terminology used in this specification of embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of the invention. As used in this specification of embodiments of the invention and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0055] The effect of the addition method of monomers or polymers with chemical functional groups capable of thermal cross-linking (b) on the properties of the slurry was investigated.

[0056] Example 1

[0057] Aluminum nitride powder and sintering aid YAG were weighed at a mass ratio of 95:5, and anhydrous ethanol was used as the grinding medium. The mixture was then ball-milled in a planetary ball mill at 350 rpm for 6 hours. Next, 2 wt% of polyethyleneimine and a silane coupling agent (1:1) were added dropwise, and ball-milling continued for 3 hours. The mixture was then dried using a rotary evaporator and sieved to obtain a uniformly mixed and modified AlN composite powder. A photosensitive resin suitable for photocurable additive manufacturing was prepared by mixing 8 g of terpineol, 2 g of dipentaerythritol hexaacrylate, and 0.2 g of photoinitiator (Omnirad 651). The modified ceramic powder and photosensitive resin were then homogenized in a homogenizer at 2200 rpm for 5 minutes to obtain a 30 vol% AlN ceramic slurry. The viscosity of the slurry was measured using a rotational rheometer, where the viscosity was highest at a shear rate of 35 s⁻¹. -1 At that time, its viscosity was 1.64 Pa·s, and the specific rheological curve is as follows: Figure 1 As shown.

[0058] Comparative Example 1

[0059] Aluminum nitride powder and sintering aid YAG were weighed at a mass ratio of 95:5, and anhydrous ethanol was used as the grinding medium. The mixture was then ball-milled in a planetary ball mill at 350 rpm for 6 hours. Then, 1 wt% of silane coupling agent was added dropwise, and ball milling continued for 3 hours. The mixture was then dried using a rotary evaporator and sieved to obtain a uniformly mixed and modified AlN composite powder. A photosensitive resin suitable for photocurable additive manufacturing was prepared by mixing 0.5 g of polyethyleneimine, 8 g of terpineol, 2 g of dipentaerythritol hexaacrylate, and 0.2 g of photoinitiator (Omnirad 651). The modified ceramic powder and photosensitive resin were then homogenized in a homogenizer at 2200 rpm for 5 minutes to obtain a 30 vol% AlN ceramic slurry. The viscosity of the slurry was measured using a rotational rheometer at a shear rate of 35 s⁻¹. -1 At that time, its viscosity was 3.22 Pa·s, and the specific rheological curve is as follows: Figure 1 As shown.

[0060] It can be seen that by introducing monomers or polymers (b) with chemical functional groups that can achieve thermal crosslinking reaction (taking polyethyleneimine as an example in this experiment) as surface modifiers into the surface of structural ceramics, they can be combined with reagents such as silane coupling agents that are beneficial to improving the compatibility of powder and resin, which is conducive to reducing the viscosity of slurry.

[0061] Example 2

[0062] A high-solids-content (50 vol%) AlN ceramic slurry was prepared according to the slurry preparation process in Example 1. Multiple printed green bodies were obtained by curing the AlN ceramic slurry using a desktop DLP printer.

[0063] The green body was placed between two porous absorbent carbon felts. A gradually increasing current was passed through both ends of the carbon felts while maintaining a constant voltage of 18V. The heating rate of the carbon felts was adjusted to 20℃ / min, raising the temperature to 150℃, 250℃, 350℃, 450℃, and 550℃, respectively, and holding at these temperatures for 60 minutes. Afterward, the power was turned off, and the sample was allowed to cool to room temperature with the furnace, obtaining the degreased green body. In this embodiment, a photograph of the green body after degreasing at a rate of 20℃ / min to 550℃ is shown below. Figure 2 and Figure 3 (c) Upon observation, the surface of the degreased blank was intact and without cracks.

[0064] The bending strength of the billet at different degreasing temperatures was tested, and the results are shown in Table 1.

[0065] Table 1. Bending strength of green bodies at different degreasing temperatures

[0066] Degreasing temperature (°C) Flexural strength of billet (MPa) Printing green blanks 14.5 150 19.2 250 26.3 350 22.6 450 12.4 550 8.8

[0067] Example 3

[0068] The difference between this embodiment and Embodiment 2 is that: the heating rate of the carbon felt is adjusted to 50℃ / min to raise it to 550℃, held at that temperature for 60min, and then cooled to room temperature at a rate of 20℃ / min to obtain the degreased green body. (See...) Figure 2 and Figure 3 (d) Upon observation, the surface of the degreased blank was intact and without cracks.

[0069] Example 4

[0070] The difference between this embodiment and Embodiment 3 is that the degreased green body is placed between two porous liquid-absorbing carbon felts, and a gradually increasing current is passed through both ends of the carbon felts while maintaining a constant voltage of 31V. The temperature is raised to 1850℃ at 500℃ / min and held for 10s, then the power is turned off to allow the sample to cool down with the furnace, achieving sintering and obtaining AlN ceramics.

[0071] Example 5

[0072] The difference between this embodiment and Embodiment 3 is that the degreased green body is placed between two porous liquid-absorbing carbon felts, and a gradually increasing current is passed through both ends of the carbon felts while maintaining a constant voltage of 31V. The temperature is raised to 1850℃ at 500℃ / min and held for 20s, then the power is turned off to allow the sample to cool down with the furnace, achieving sintering and obtaining AlN ceramics.

[0073] Example 6

[0074] The difference between this embodiment and Embodiment 3 is that the degreased green body is placed between two porous liquid-absorbing carbon felts, and a gradually increasing current is passed through both ends of the carbon felts while maintaining a constant voltage of 31V. The temperature is raised to 1850℃ at 500℃ / min and held for 30s, then the power is turned off to allow the sample to cool down with the furnace, achieving sintering and obtaining AlN ceramics.

[0075] Example 7

[0076] The difference between this embodiment and Embodiment 3 is that the degreased green body is placed between two porous liquid-absorbing carbon felts, and a gradually increasing current is passed through both ends of the carbon felts while maintaining a constant voltage of 31V. The temperature is raised to 1950℃ at 500℃ / min and held for 10s, then the power is turned off to allow the sample to cool down with the furnace, achieving sintering and obtaining AlN ceramics.

[0077] Example 8

[0078] The difference between this embodiment and Embodiment 3 is that the degreased green body is placed between two porous liquid-absorbing carbon felts, and a gradually increasing current is passed through both ends of the carbon felts while maintaining a constant voltage of 31V. The temperature is raised to 1950℃ at 500℃ / min and held for 20s, then the power is turned off to allow the sample to cool down with the furnace, achieving sintering and obtaining AlN ceramics.

[0079] Example 9

[0080] The difference between this embodiment and Embodiment 3 is that the degreased green body is placed between two porous absorbent carbon felts, and a gradually increasing current is passed through both ends of the carbon felts while maintaining a constant voltage of 31V. The temperature is raised to 1950℃ at 500℃ / min and held for 30s, then the power is turned off to allow the sample to cool down with the furnace, achieving sintering and obtaining AlN ceramics.

[0081] Example 10

[0082] Rare earth oxide stabilized zirconia powder and sintering aid Cr2O3 were weighed at a mass ratio of 95:5, and anhydrous ethanol was used as the grinding medium. The mixture was then ball-milled in a planetary ball mill at 350 rpm for 6 hours. Next, 2 wt% of polyethyleneimine and silane coupling agent (1:1) were added dropwise, and ball-milling continued for 3 hours. The mixture was then dried using a rotary evaporator and sieved to obtain a uniformly mixed and modified AlN composite powder. A photosensitive resin suitable for photocurable additive manufacturing was prepared by mixing 8 g of terpineol, 2 g of dipentaerythritol hexaacrylate, and 0.2 g of photoinitiator (Omnirad 651). The modified ceramic powder and photosensitive resin were then homogenized and stirred at 2200 rpm for 5 minutes in a homogenizer to obtain a 50 vol% zirconia ceramic slurry with a high solid content. The zirconia ceramic slurry was then cured using a desktop DLP printer to obtain a printed green body.

[0083] The green body was placed between two porous absorbent carbon felts, and a gradually increasing current was passed through both ends of the carbon felts while maintaining a constant voltage of 18V. The heating rate of the carbon felts was adjusted to 50℃ / min, and the temperature was raised to 550℃, held for 60min, and then cooled to room temperature at a rate of 20℃ / min to obtain the degreased green body. Upon observation, the surface of the degreased green body was intact and without cracks.

[0084] The degreased green body was placed between two porous absorbent carbon felts, and a gradually increasing current was passed through both ends of the carbon felts while maintaining a constant voltage of 31V. The green body was heated to 1550℃ at a rate of 500℃ / min and held for 10s. Then the power was turned off and the sample was allowed to cool down with the furnace to obtain zirconia ceramic.

[0085] Example 11

[0086] The difference between this embodiment and Embodiment 10 is that the degreased green body is placed between two porous absorbent carbon felts, and a gradually increasing current is passed through both ends of the carbon felts while maintaining a constant voltage of 31V. The green body is heated to 1550℃ at 500℃ / min and held for 20s, then the power is turned off to allow the sample to cool down with the furnace, thus obtaining zirconia ceramic.

[0087] Example 12

[0088] The difference between this embodiment and Embodiment 10 is that the degreased green body is placed between two porous absorbent carbon felts, and a gradually increasing current is passed through both ends of the carbon felts while maintaining a constant voltage of 31V. The green body is heated to 1550℃ at 500℃ / min and held for 30s, then the power is turned off to allow the sample to cool down with the furnace, thus obtaining zirconia ceramic.

[0089] The ceramics prepared in Examples 4-12 were subjected to performance tests, and the results are shown in Table 2.

[0090] Table 2. Ceramic performance data obtained in Examples 4-12

[0091] Relative density (%) Strength (MPa) Hardness (GPa) <![CDATA[Toughness (MPa·m 1 / 2 )]]> Example 4 79.97 216±22.8 7.05 1.89 Example 5 88.05 257±26.55 7.72 2.15 Example 6 95.86 369±32.25 8.83 3.07 Example 7 91.17 330±54.63 8.17 2.88 Example 8 98.37 455±30.77 10.76 3.84 Example 9 99.70 493±32.64 11.81 3.56 Example 10 92.33 405±47.88 12.3 2.97 Example 11 97.61 723±57.65 14.33 4.31 Example 12 99.58 932±65.76 14.98 4.85

[0092] The cross-sectional SEM images of the aluminum nitride ceramic samples obtained in Examples 4-9 are shown below. Figure 4 As shown in Table 2, the ultra-fast debinding and sintering method described in this invention can achieve rapid densification of the green body for both aluminum nitride (AlN) and zirconia (ZrO2) ceramics, significantly shortening the process cycle. Furthermore, by adjusting the sintering temperature and holding time, the microstructure of the ceramic can be optimized, thereby improving the strength, hardness, and toughness of the ceramic material.

[0093] Comparative Example 2

[0094] Aluminum nitride powder and sintering aid YAG were weighed at a mass ratio of 95:5. Anhydrous ethanol was used as the grinding medium, and the mixture was then ball-milled in a planetary ball mill at a speed of 350 rpm for 6 hours. Then, 2 wt% of silane coupling agent was added dropwise, and the mixture was ball-milled for another 3 hours. The mixture was then dried by a rotary evaporator and sieved to obtain a uniformly mixed and modified AlN composite powder. A photosensitive resin suitable for photocurable additive manufacturing was prepared by mixing 2.3g pentaerythritol tetraacrylate (PPTTA), 2.5g 1,6-hexanediol diacrylate (HDDA), 1.7g polyurethane acrylate (U600), 1.5g polyethylene glycol (PEG-300), 2g n-octanol, and 0.2g photoinitiator (Omnirad 651). Subsequently, the modified ceramic powder and the photosensitive resin were stirred in a homogenizer at 2200 rpm for 5 minutes to obtain a high solid content (50 vol%) AlN ceramic slurry. The AlN ceramic slurry was then cured and molded using a desktop DLP printer to obtain a printed green body.

[0095] The green body was placed between two porous absorbent carbon felts. A gradually increasing current was passed through both ends of the carbon felts while maintaining a constant voltage of 18V. The heating rate of the carbon felts was adjusted to 20℃ / min, raising the temperature to 550℃ and holding it at that temperature for 60min. Then, the temperature was lowered to room temperature at a rate of 20℃ / min to obtain the degreased green body. (See attached image) Figure 2 and Figure 3 In (a), it was observed that the degreased blank was partially broken and macroscopic cracks remained on the sample.

[0096] Comparative Example 3

[0097] Aluminum nitride powder and sintering aid were weighed at a mass ratio of 95:5, and anhydrous ethanol was used as the grinding medium. The mixture was then ball-milled in a planetary ball mill at a speed of 350 rpm for 6 hours. Then, 2 wt% of silane coupling agent was added dropwise, and the mixture was ball-milled for another 3 hours. The mixture was then dried by a rotary evaporator and sieved to obtain a uniformly mixed and modified AlN composite powder. A photosensitive resin suitable for photocurable additive manufacturing was prepared by mixing 2.3g pentaerythritol tetraacrylate (PPTTA), 2.5g 1,6-hexanediol diacrylate (HDDA), 1.7g polyurethane acrylate (U600), 1.5g polyethylene glycol (PEG-300), 2g n-octanol, and 0.2g photoinitiator (Omnirad651). Subsequently, the modified ceramic powder and the photosensitive resin were stirred in a homogenizer at 2200 rpm for 5 min to obtain a high solid content 50 vol% AlN ceramic slurry. The AlN ceramic slurry was then cured and molded using a desktop DLP printer to obtain a printed green body.

[0098] The green body was placed between two porous absorbent carbon felts. A gradually increasing current was passed through both ends of the carbon felts while maintaining a constant voltage of 18V. The heating rate of the carbon felts was adjusted to 50℃ / min, raising the temperature to 550℃ and holding it at that temperature for 60min. Then, the temperature was lowered to room temperature at a rate of 50℃ / min to obtain the degreased green body. (See attached image) Figure 2 and Figure 3 In (b), it was observed that the degreased blank was partially fractured and macroscopic cracks remained on the sample.

[0099] Comparative Example 4

[0100] Rare earth oxide stabilized zirconia powder and sintering aid were weighed at a mass ratio of 95:5, and anhydrous ethanol was used as the grinding medium. The mixture was then ball-milled in a planetary ball mill at a speed of 350 rpm for 6 hours. Then, 2 wt% of silane coupling agent was added dropwise, and the mixture was ball-milled for another 3 hours. The mixture was then dried by a rotary evaporator and sieved to obtain a uniformly mixed and modified AlN composite powder. A photosensitive resin suitable for photocurable additive manufacturing was prepared by mixing pentaerythritol tetraacrylate (PPTTA), 1,6-hexanediol diacrylate (HDDA), polyurethane acrylate (U600), polyethylene glycol (PEG-300), n-octanol, and a photoinitiator (Omnirad 651). Subsequently, the modified ceramic powder and the photosensitive resin were stirred in a homogenizer at 2200 rpm for 5 min to obtain a high solid content AlN 50 vol% ceramic slurry. The AlN ceramic slurry was then cured and molded using a desktop DLP printer to obtain a printed green body.

[0101] The green body was placed between two porous absorbent carbon felts, and a gradually increasing current was passed through both ends of the carbon felts while maintaining a constant voltage of 18V. The heating rate of the carbon felts was adjusted to 50℃ / min, and the temperature was raised to 550℃, held for 60min, and then cooled to room temperature at a rate of 50℃ / min to obtain the degreased green body. Upon observation, the degreased green body showed partial fractures and macroscopic cracks.

[0102] The ceramic slurries of Comparative Examples 2-4 do not contain monomers or polymers with chemical functional groups that can achieve thermal cross-linking reactions (b), and the green bodies have insufficient strength under rapid heating during debinding (at a rate of 20-50℃ / min).

[0103] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0104] The above description describes specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high performance ceramic ultra-fast debinding and sintering method based on light-cured additive manufacturing, characterized in that, The method comprises the following steps: Preparation of high solid content photocured ceramic slurry containing: (a) at least one monomer or polymer of chemical functional groups capable of photo-crosslinking reaction, 1-20wt%; (b) at least one monomer or polymer of chemical functional groups capable of thermal-crosslinking reaction, 0.5-5wt%; (c) at least one low molecular weight solvent, 8.5-39wt%; (d) high performance ceramic powder, 60-90wt%; (e) at least one photoinitiator, 0.5-5wt% of the monomer or polymer of chemical functional groups capable of photo-crosslinking reaction; Photocured molding to obtain a printed green body; Super-fast high-temperature sintering equipment based on Joule heating for super-fast debinding and super-fast high-temperature sintering of the printed green body.

2. The high performance ceramic ultrafast debinding and sintering process based on light solidification additive manufacturing of claim 1, wherein, The photocured crosslinking reaction temperature of the monomer or polymer of chemical functional groups capable of photo-crosslinking reaction is 0-60℃.

3. The high performance ceramic ultrafast debinding and sintering process based on light solidification additive manufacturing as claimed in claim 1, wherein, The thermal crosslinking reaction temperature of the monomer or polymer of chemical functional groups capable of thermal-crosslinking reaction is 40-300℃.

4. The high performance ceramic ultrafast debinding and sintering process based on light solidification additive manufacturing as claimed in claim 1, wherein, The monomer or polymer of chemical functional groups capable of thermal-crosslinking reaction is selected from at least one monomer or polymer of secondary amine, primary amine and tertiary amine.

5. The high performance ceramic ultrafast debinding and sintering process based on light solidification additive manufacturing as claimed in claim 1, wherein, The photocured ceramic slurry further comprises a surface modifier, and the surface modifier and the monomer or polymer of chemical functional groups capable of thermal-crosslinking reaction are mixed with the high performance ceramic powder in advance to modify the surface of the high performance ceramic powder, and then the monomer or polymer of chemical functional groups capable of photo-crosslinking reaction and the low molecular weight solvent are added to prepare the photocured ceramic slurry.

6. The high performance ceramic ultrafast debinding and sintering process based on light solidification additive manufacturing as claimed in claim 1, wherein, The low molecular weight solvent is selected from terpineol, polyethylene glycol, water, ethanol, toluene, tetrahydrofuran, mixtures thereof and modified products.

7. The high performance ceramic ultrafast debinding and sintering process based on light solidification additive manufacturing as claimed in claim 1 wherein, The temperature rising rate of the super-fast debinding is 10-100℃ / min, and the holding time is 5 seconds to 180 minutes.

8. The high performance ceramic ultrafast debinding and sintering process based on light solidification additive manufacturing as claimed in claim 1, wherein, The temperature rising rate of the super-fast high-temperature sintering is not less than 200℃ / min, and the holding time is 1 second to 60 minutes.

9. A method of producing high performance ceramics, characterized by, The method for super-fast debinding and sintering of high performance ceramics based on photocured additive manufacturing according to any one of claims 1-8.

10. A high performance ceramic characterized by, Prepared by the preparation method according to claim 9.

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