Laser-assisted gel forming additive manufacturing device and method

Abstract

The invention relates to the technical field of ceramic material forming, in particular to a laser-assisted gel forming additive manufacturing device and method. A shell in the device comprises an upper shell and a lower shell. The lower shell is provided with a lifting platform to realize independent lifting adjustment of the height; the displacement mechanism comprises a first guide rail and a second guide rail; the first guide rail is installed on the side face of the lower shell. The second guide rail is installed on the first guide rail. The forming mechanism comprises a forming groove, an injection unit and a scraper; the scraper and the printing nozzle are parallel to the forming groove; the spraying unit is installed on the second guide rail to independently move in the horizontal Y-axis direction and is driven by the second guide rail to move on the first guide rail. During working, the spraying unit sprays a reagent to a forming groove area according to a specific path; the environment control mechanism ensures the sealing performance of the device; and the laser operation mechanism irradiates different positions in the forming process. The method has the advantages that the prepared ceramic material not only has high performance of a traditional material, but also has a high-complexity structure of additive manufacturing.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic material forming, and in particular to a laser-assisted gel forming additive manufacturing device and method. Background Art

[0002] Gel injection molding technology is a typical traditional preparation technology for advanced ceramics. This technology has the advantages of a wide range of powder materials and high green body performance. It is widely used in the research and development and production of ceramic structural parts such as carbides and oxides. Generally, gel injection molding technology is to mix organic monomers and ceramic powders into a low-viscosity, high-solid content ceramic slurry. Under the action of catalysts, initiators, etc., the organic monomers are caused to undergo cross-linking polymerization to form a three-dimensional network structure, and the ceramic particles are solidified and formed in situ. With the continuous development of aerospace, petrochemical, rail transportation and other fields, structural ceramics have been put forward functional requirements such as athermalization, lightweight, and integration. This requires ceramic structural parts to have complex structures with corresponding functions. Although gel injection molding technology is a near-net-size molding technology, there are still insurmountable technical barriers in the preparation of highly complex structures such as extremely small surfaces and lattice structures.

[0003] Additive manufacturing technology, based on the principle of layer-by-layer stacking, has brought about a disruptive technological change in the preparation of ceramics with highly complex structures. To date, this technology can be divided into more than ten types, such as laser selective sintering, binder injection molding, and photocuring, which can realize the preparation of materials of any structure. However, additive manufacturing technology has specific requirements for powders. For example, photocuring technology is difficult to achieve the preparation of high-solid content preforms when preparing carbides or nitride ceramics with high absorbance. At the same time, the performance of ceramic materials currently prepared by additive manufacturing technology is far lower than that of ceramics prepared by traditional preparation technology. Although additive manufacturing technology has obvious technical advantages in the preparation of complex structural ceramics, problems such as limited powder material and poor green body performance have restricted the development and application of additive manufacturing technology.

[0004] Existing additive manufacturing technologies can be divided into two categories based on the form of the raw materials: powder bed molding and ceramic slurry molding. Typical powder bed molding technologies include selective laser sintering (SLS) and binder jetting (BJP), while representative ceramic slurry molding technologies include stereolithography (SLA / DLP). Due to the limited packing density of powders, it is difficult to obtain high-solid-phase preforms. Therefore, ceramic slurry molding technology is more advantageous when preparing high-solid-content ceramic preforms. However, stereolithography requires a high penetration depth of light in the slurry, and currently faces the problem of being unable to simultaneously achieve a high penetration depth and a high solid-phase content (usually less than 50%), especially for ceramic materials such as silicon carbide and silicon nitride, which have high absorbance. Summary of the Invention

[0005] The present invention provides a laser-assisted gel molding additive manufacturing device and method to solve the problems of limited powder material, poor green body performance and low solid content of special ceramic preforms in existing additive manufacturing technologies.

[0006] The first object of the present invention is to provide a laser-assisted gel forming additive manufacturing device, comprising a housing, a displacement mechanism, a material storage mechanism, a forming mechanism, an environmental control mechanism, and a laser operating mechanism; The housing comprises an upper housing and a lower housing; the lower housing is provided with at least two lifting platforms to achieve independent height adjustment of objects placed on the lifting platforms; the upper housing and the lower housing are sealed in the working state; The displacement mechanism includes a first guide rail and a second guide rail; the first guide rail is installed on the side of the lower shell; the second guide rail is installed on the first guide rail and moves along the first guide rail in the horizontal X-axis direction; The storage mechanism includes a storage tank for storing special ceramic slurry; The molding mechanism includes a molding trough, a spray unit, and a scraper; the scraper is mounted on a first guide rail on the side of the lower housing and is used to spread the slurry in the storage tank into the molding trough; the molding trough is placed horizontally and is used to carry and solidify the ceramic slurry; the scraper and the print head are parallel to the molding trough; the spray unit is mounted on a second guide rail and independently moves in the horizontal Y-axis direction, and is driven by the second guide rail to move on the first guide rail; when in operation, the spray unit sprays a certain amount of initiator or curing agent into the molding trough area along a specific path; The environmental control mechanism is mounted on the upper housing and is used to control the inflow and outflow of gas to ensure the sealing of the device; The output laser of the laser operation mechanism covers the forming groove and irradiates different positions during the forming process.

[0007] Preferably, it also includes a first limit switch and a second limit switch; the first limit switch and the second limit switch are used to limit the positions of the scraper and the second guide rail on the first guide rail respectively to prevent movement beyond the designed stroke.

[0008] Preferably, the injection unit includes a print head and a conduit; the print head is mounted on a second guide rail; the print head independently realizes movement in the horizontal Y-axis direction on the second guide rail, and realizes movement on the first guide rail driven by the second guide rail, that is, movement in the horizontal X-axis direction; the conduit is connected to a feeding device containing an initiator or a curing agent, and the initiator or the curing agent is transported to the print head through the conduit, and the print head sprays a certain amount of initiator or curing agent along a specific path; the position and injection path of the print head are controlled by a computer to ensure the precise distribution of the initiator or the curing agent.

[0009] Preferably, two lifting platforms are provided in the lower shell, which are used to place the storage trough and the molding trough respectively, and realize independent lifting and adjusting of the height of the storage trough and the molding trough to meet different molding requirements; a sealing gasket is installed at the connection between the upper shell and the lower shell to prevent gas leakage.

[0010] Preferably, the laser operation mechanism includes a laser, a beam shaping unit, and a scanning mirror arranged in sequence along the optical path; the laser provides a laser source for slurry heating; the beam shaping unit collimates and shapes the laser beam emitted by the laser to improve the output beam quality; the scanning mirror is used to control the beam direction; The laser is a fiber laser, a YAG laser, a CO2 laser, or a semiconductor laser; the laser power of the laser is 5-50W, and the laser scanning rate is 800-2500mm / s.

[0011] Preferably, the laser is a CO2 laser with a wavelength of 10.6 μm and a minimum spot size of 80-90 μm; The first guide rail and the second guide rail are in a perpendicular relationship.

[0012] The second object of the present invention is to provide a laser-assisted gel forming additive manufacturing method, which is prepared using the laser-assisted gel forming additive manufacturing device and specifically includes the following steps: S1. The ceramic powder, organic monomer, crosslinking agent, and dispersant are mixed in a certain proportion and degassed to obtain a ceramic slurry; S2. The ceramic slurry prepared in step S1 is poured into the storage tank; S3. Seal the laser-assisted gel-forming additive manufacturing device, evacuate the device, and maintain the vacuum environment or fill it with an inert gas; S4. The molding tank and the storage tank are lowered or raised to the corresponding height, and the ceramic slurry is scraped out from the storage tank with a scraper and spread into the molding tank; the scraper then returns to its initial position; S5. Start the ejection unit, the print head starts from the standby position, and sprays the initiator or fixative along a specific path. After the ejection is completed, the print head returns to the standby position; S6. The laser operation mechanism is activated, and the laser emits a laser beam, which is adjusted by the beam shaping unit and the scanning mirror and then irradiated to the initiator area, accelerating the induction period and promoting the rapid polymerization of the organic matter. The laser operation is completed after a period of irradiation. S7. Repeat steps S4 to S7 until the program ends, completing the printing and obtaining the ceramic preform.

[0013] Preferably, the mixing in step S1 is ball milling for 1 to 5 hours, and the degassing is vacuum degassing.

[0014] Preferably, the ceramic powder includes aluminum oxide, silicon carbide, aluminum nitride, and silicon nitride; The organic monomer includes acrylamide, isobutylene maleic anhydride polymer, chitosan, agarose, methacrylamide, acrylic acid, butadiene or furfuryl alcohol; The cross-linking agent is methyl acrylate, N,N'-methylenebisacrylamide, polybismethacrylic acid or glutaraldehyde; The dispersant includes ammonium polyacrylate, ammonium citrate, ammonium polymethacrylate, sodium hexametaphosphate, and polyethylene glycol; The initiator or curing agent includes hydrogen peroxide, benzoic acid peroxide, sodium persulfate, potassium persulfate, sulfonyl chloride, ammonium persulfate or azo initiator.

[0015] Preferably, step S1 includes the following sub-steps: S11. The organic monomer, crosslinking agent, and solvent are mixed in a certain proportion and stirred to obtain a premixed solution; S12. Ceramic powder and dispersant are added to the premixed liquid, mixed by ball milling, and then vacuum degassing is performed to obtain a ceramic slurry.

[0016] Compared with the prior art, the present invention can achieve the following beneficial effects: To address the low solids content problem of specialty ceramic preforms produced using existing additive manufacturing techniques, this invention leverages the fundamental principles of gelcasting to combine conventional specialty ceramic preparation techniques with additive manufacturing, leveraging the advantages of high solids content in conventional ceramic preforms with the complex shape forming capabilities of additive manufacturing. The invention provides a manufacturing method that utilizes a high-solids content ceramic slurry (greater than 65%) produced using gelcasting and uses a laser as a heat source to assist in thermal curing of the slurry, addressing the difficulties of photocuring in existing additive manufacturing ceramic slurries. Furthermore, the powder particle composition in the slurry can be regulated to optimize material properties. Ceramics produced using the laser-assisted gelcasting additive manufacturing device and method of the present invention combine the high material properties of conventional methods with the highly complex structures of additively manufactured ceramics. This leverages the advantages of both technologies to achieve high-performance production of complex ceramic structures, significantly expanding the application range of specialty ceramics and extending their service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the overall structure of a laser-assisted gel-forming additive manufacturing device provided according to an embodiment of the present invention.

[0018] Figure 2 Schematic diagram of the internal structure of the laser operating mechanism of the laser-assisted gel forming additive manufacturing device provided according to an embodiment of the present invention.

[0019] Figure 3The figure is a flow chart of a laser-assisted gel forming additive manufacturing method according to an embodiment of the present invention.

[0020] Reference numerals: 1. Inflatable valve; 2. Butterfly valve; 3. Scraper; 4. Storage tank; 5. First guide rail; 6. First limit switch; 7. Second limit switch; 8. Molding groove; 9. Print nozzle; 10. Catheter; 11. Second guide rail; 12. Upper shell; 13. Lower housing; 14. Laser operating mechanism; 141. Laser; 142. Beam shaping unit; 143. Scanning mirror; 144. Laser beam. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, identical modules are denoted by identical reference numerals. In the case of identical reference numerals, their names and functions are also identical. Therefore, their detailed description will not be repeated.

[0022] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0023] The present invention provides a laser-assisted gel molding additive manufacturing device, which is used to prepare special ceramic preforms through gel casting molding technology, has good sealing performance, and is used to achieve a vacuum or inert gas environment; Figure 1-Figure 2 The device includes: a housing, a displacement mechanism, a material storage mechanism, a molding mechanism, an environmental control mechanism and a laser operation mechanism 14, each of which works together to achieve efficient and high-quality ceramic preform molding; The housing includes an upper housing 12 and a lower housing 13; the lower housing 13 is provided with at least two lifting platforms to achieve independent height adjustment of objects placed on the lifting platforms; specifically, the two lifting platforms are provided to respectively place the material storage trough 4 and the forming trough 8, and achieve independent height adjustment of the material storage trough 4 and the forming trough 8 to meet different forming requirements; a sealing gasket is installed at the connection between the upper housing 12 and the lower housing 13 to prevent gas leakage; In a specific embodiment, the lifting platform is a Z-axis servo lifting platform, which is composed of a closed-loop control unit consisting of a servo motor, a ball screw, etc. The servo motor drives the ball screw to realize the lifting movement of the lifting platform in the Z-axis direction. The computer program receives the layer height, liquid level or process parameter instructions in real time to accurately control the lifting height of the storage tank 4 and the forming tank 8. The positioning accuracy is better than ±0.01mm, ensuring that the slurry thickness matches the laser action area.

[0024] The displacement mechanism includes a first guide rail 5 and a second guide rail 11; the first guide rail 5 is installed on the side of the lower shell 13; the second guide rail 11 (secondary guide rail) is installed on the first guide rail 5 through a bracket, and the second guide rail 11 moves horizontally along the first guide rail 5 in the X-axis direction, and the first guide rail 5 and the second guide rail 11 are in a vertical relationship.

[0025] The storage mechanism includes a storage tank 4 for storing special ceramic slurry; The forming mechanism includes a forming tank 8, a spray unit, and a scraper 3; The scraper 3 is mounted on the first guide rail 5 on the side of the lower housing 13. The movement of the scraper 3 on the first guide rail 5 is precisely controlled by a computer to spread the slurry in the storage tank 4 into the forming tank 8 to ensure uniform distribution of the slurry. The spray unit includes a print head 9 and a conduit 10. The print head 9 is mounted on a second guide rail 11. The print head 9 can independently move in the horizontal Y-axis direction on the second guide rail 11 and, driven by the second guide rail 11, can move in the horizontal X-axis direction on the first guide rail 5. The conduit 10 is connected to a feeding device containing reagents such as an initiator or a curing agent. The initiator or curing agent is transported to the print head 9 through the conduit 10. The print head 9 sprays a predetermined amount of initiator or curing agent along a specific path toward the molding groove 8. The position and spray path of the print head 9 are computer-controlled to ensure precise distribution of the initiator or curing agent. The forming tank 8 is placed horizontally to carry and solidify the ceramic slurry; the scraper 3 and the printing nozzle 9 are parallel to the forming tank 8 to ensure uniform distribution of the slurry and accurate injection of the initiator (or curing agent); The material storage trough 4 and the forming trough 8 are respectively placed on two independent lifting platforms of the lower shell 13. When ready to work, the lifting platforms make the forming trough 8 and the material storage trough 4 descend or rise to corresponding heights.

[0026] The environmental control mechanism includes an inflation valve 1 and a butterfly valve 2 installed on the upper shell 12, which are used to control the inflow and outflow of gas to ensure the sealing of the entire device; the inflation valve 1 is used to inject inert gas into the working area to exclude oxygen and prevent the free radical polymerization process from being inhibited; the butterfly valve 2 is used to control the inflow and outflow of inert gas to maintain the inert gas environment in the working area; specifically, sealing gaskets are installed around the mounting holes of the inflation valve 1 and the butterfly valve 2 to prevent gas leakage; the sealing gaskets are made of chemically resistant materials such as fluororubber or polytetrafluoroethylene; the inflation valve 1 and the butterfly valve 2 are fixed to the upper shell 12 by fasteners such as bolts and nuts to ensure close contact between the valves and the shell, thereby achieving a good sealing effect.

[0027] like Figure 2 As shown, the laser operating mechanism 14 includes a laser 141, a beam shaping unit 142, and a scanning mirror 143 arranged in sequence along the optical path. The laser 141 provides a laser source for slurry heating and is used to provide heat for the organic monomer curing process. The beam shaping unit 142 collimates and shapes the laser beam emitted by the laser 141 to improve the output beam quality. The scanning mirror 143 is used to control the beam direction. The laser beam 144 is used as the output laser to directly heat the printing area. The laser operating mechanism 14 is installed in a position that ensures that its beam can cover the entire area of ​​the molding groove 8, so as to facilitate irradiation of the initiator at different positions during the molding process. Specifically, the laser operating mechanism 14 has a laser power of 10-50W and a laser scanning rate of 1000-1600 mm / s. The design of the laser operating mechanism 14 ensures that the laser can evenly irradiate the initiator area, thereby accelerating the curing process and improving the molding efficiency. The laser 141 is a fiber laser, a YAG laser, a CO2 laser, a semiconductor laser, etc., and its specific type can be selected according to actual needs; preferably, a CO2 laser with a wavelength of 10.6 μm and a minimum spot size of 80-90 μm.

[0028] The device also includes a first limit switch 6 and a second limit switch 7; the first limit switch 6 and the second limit switch 7 are respectively used to limit the positions of the scraper 3 and the second guide rail 11 on the first guide rail 5 to prevent the components from moving beyond their designed stroke and avoid impact or damage to the equipment.

[0029] The present invention also provides a laser-assisted gel forming additive manufacturing method, that is, a method for preparing a ceramic preform; the preparation is performed using the laser-assisted gel forming additive manufacturing device of the present invention, and specifically includes the following steps: S1. Preparation of ceramic slurry; mixing ceramic powder, organic monomer, crosslinking agent, dispersant in a certain proportion, degassing, to obtain a ceramic slurry; Specifically, ceramic powders include but are not limited to alumina, silicon carbide, aluminum nitride, etc.; organic monomers include but are not limited to acrylamide, isobutylene maleic anhydride polymer, chitosan, agarose, methacrylamide, acrylic acid, butadiene, furfuryl alcohol, etc.; crosslinking agents include methyl acrylate, N,N'-methylenebisacrylamide, polydimethyl methacrylate, or glutaraldehyde, etc.; dispersants include but are not limited to ammonium polyacrylate, ammonium citrate, ammonium polymethacrylate, sodium hexametaphosphate, polyethylene glycol, etc.; Specifically, the mixing is performed by ball milling for 1 to 5 hours, and the degassing is performed by vacuum degassing; Specifically, the following sub-steps are included: S11. The organic monomer, crosslinking agent, and solvent are mixed in a certain proportion and stirred to obtain a premixed solution; S12 ceramic powder and dispersant were added to the premix, ball-milled, and vacuum degassed to obtain a ceramic slurry; S2. The ceramic slurry prepared in step S1 is poured into the storage tank; S3. Seal the laser-assisted gel-forming additive manufacturing device, evacuate the device, and maintain the vacuum environment or fill it with an inert gas; S4. The molding tank and the storage tank are lowered or raised to the corresponding height, and the ceramic slurry is scraped out from the storage tank with a scraper and spread into the molding tank; S5. Start the ejection unit, the print head starts from the standby position, and sprays the initiator or fixative along a specific path. After the ejection is completed, the print head returns to the standby position; The initiator includes but is not limited to hydrogen peroxide, benzoic acid peroxide, sodium persulfate, potassium persulfate, etc.; S6. The laser operation mechanism is activated, and the laser emits a laser beam, which is adjusted by the beam shaping unit and the scanning mirror and then irradiated to the initiator area, accelerating the induction period and promoting the rapid polymerization of the organic matter. The laser operation is completed after a period of irradiation. S7. Repeat steps S4 to S7 until the program ends, completing the printing and obtaining the ceramic preform.

[0030] The ceramic preform forming principles of the present invention include: (1) crosslinking and curing of organic monomers under the action of initiators, catalysts, etc., with laser heat source accelerating the curing rate; and (2) organic monomers themselves have crosslinking activity, which leads to self-curing under the action of laser heat source. Specific examples are listed below to further illustrate this.

[0031] Example 1 A method for preparing a silicon nitride ceramic preform is provided, wherein the method adopts the laser-assisted gel-molding additive manufacturing device of the present invention for preparation; the laser adopts a carbon dioxide laser with a laser power of 5 to 20 W, a scanning speed of 800 to 2500 mm / s, and a scanning pitch of 0.1 to 0.3 mm; and the method specifically comprises the following steps: S1. Preparation of ceramic slurry: S11. An organic monomer, a crosslinking agent, and a solvent are mixed in a certain proportion and stirred to obtain a premixed solution; wherein the organic monomer is furfuryl alcohol; the crosslinking agent is a phenolic resin; the solvent is ethylene glycol; the mass ratio of ethylene glycol:furfuryl alcohol:phenolic resin is 2:1:1, and ethylene glycol is 10-30% of the total mass of the silicon nitride ceramic powder; S12. Ceramic powder and dispersant are added to the premixed solution, ball-milled for 2 hours, and then vacuum-degassed to obtain a ceramic slurry; wherein the ceramic powder is silicon nitride ceramic powder; the dispersant is one or more of ammonium polymethacrylate, sodium hexametaphosphate, and polyethylene glycol, and the dispersant accounts for 1 to 3% of the mass of the silicon nitride ceramic powder; S2. The ceramic slurry prepared in step S1 is poured into the storage tank; S3. Seal the laser-assisted gel-forming additive manufacturing device, evacuate the device, and maintain the vacuum environment or fill it with an inert gas; S4. Lower the molding tank by 100 μm, raise the storage tank, and use a scraper to scrape the ceramic slurry from the storage tank and spread it into the molding tank; then the scraper returns to its initial position; S5. Start the ejection unit, the print head starts from the standby position, sprays the initiator according to a specific path, and after the ejection is completed, the print head returns to the standby position; The initiator includes but is not limited to hydrogen peroxide, benzoic acid peroxide, sodium persulfate, potassium persulfate, etc.; S6. The laser operation mechanism is activated, and the laser emits a laser beam. After being adjusted by the beam shaping unit and the scanning mirror, it irradiates the initiator area, initiating the cross-linking and curing reaction of the phenolic resin and furfuryl alcohol, accelerating the induction period, and promoting the rapid polymerization of the organic matter. The laser operation is completed after a period of irradiation. S7. Repeat steps S4 to S7 until the program ends, completing the printing and obtaining a silicon nitride ceramic preform.

[0032] Example 2 A method for preparing a silicon carbide ceramic preform is provided, which is prepared using the laser-assisted gel-molding additive manufacturing device of the present invention; the method specifically comprises the following steps: S1. Prepare a ceramic slurry; mix an organic monomer, a crosslinking agent, and a solvent in a certain proportion and stir to obtain a premixed solution; wherein the organic monomer is furfuryl alcohol; the crosslinking agent is a phenolic resin; and the solvent is ethylene glycol; the mass ratio of ethylene glycol:furfuryl alcohol:phenolic resin is 2:1:1, and ethylene glycol accounts for 10-30% of the total mass of the silicon carbide ceramic powder; Ceramic powder and dispersant are added to the premixed solution, ball-milled for 1 to 5 hours, and then vacuum-degassed to obtain a ceramic slurry; wherein the ceramic powder is silicon carbide ceramic powder; the dispersant is polyethylene glycol PEG400, and the dispersant accounts for 2.5% of the mass of the silicon carbide ceramic powder; S2. The ceramic slurry prepared in step S1 is poured into the storage tank; S3. Seal the laser-assisted gel-forming additive manufacturing device, evacuate the device, and maintain the vacuum environment or fill it with an inert gas; S4. Lower the forming tank by 50-200 μm and the storage tank by 80 μm. Use a scraper to scrape the ceramic slurry from the storage tank and spread it into the forming tank; then return the scraper to its original position. S5. Start the jetting unit, the print head starts from the standby position, sprays the initiator or curing agent along a specific path, and after the jetting is completed, the print head returns to the standby position; The initiator is but not limited to hydrogen peroxide, benzoic acid peroxide, sodium persulfate, potassium persulfate, etc.; the curing agent is sulfonyl chloride; S6. The laser operation mechanism is activated, and the laser emits a laser beam. After being adjusted by the beam shaping unit and the scanning mirror, it irradiates the initiator area, initiating the cross-linking and curing reaction of the phenolic resin and furfuryl alcohol, accelerating the induction period, and promoting the rapid polymerization of the organic matter. The laser operation is completed after a period of irradiation. S7. Repeat steps S4 to S7 until the program ends, completing the printing and obtaining a silicon carbide ceramic preform.

[0033] Example 3 A method for preparing an alumina ceramic preform is provided, using the laser-assisted gel-molding additive manufacturing device of the present invention for preparation; the laser power is 10-50W, and the scanning speed is 1000-1600mm / s, and the method specifically comprises the following steps: S1. Prepare a ceramic slurry; mix an organic monomer, a crosslinking agent, and a solvent in a certain proportion and stir to obtain a premixed solution; wherein the organic monomer is furfuryl alcohol; the crosslinking agent is a phenolic resin; and the solvent is ethylene glycol; the mass ratio of ethylene glycol:furfuryl alcohol:phenolic resin is 2:1:1, and ethylene glycol accounts for 10-30% of the total mass of the alumina ceramic powder; Ceramic powder and dispersant are added to the premixed solution, ball-milled for 1 to 5 hours, and then vacuum-degassed to obtain a ceramic slurry; wherein the ceramic powder is alumina ceramic powder; the dispersant is polyethylene glycol PEG400, and the dispersant accounts for 2.5% of the mass of the alumina ceramic powder; S2. The ceramic slurry prepared in step S1 is poured into the storage tank; S3. Seal the laser-assisted gel-forming additive manufacturing device, evacuate the device, and maintain the vacuum environment or fill it with an inert gas; S4. Lower the forming tank by 50-200 μm and the storage tank by 80 μm. Use a scraper to scrape the ceramic slurry from the storage tank and spread it into the forming tank; then return the scraper to its original position. S5. Start the jetting unit, the print head starts from the standby position, sprays the initiator or curing agent along a specific path, and after the jetting is completed, the print head returns to the standby position; The initiator or curing agent is sulfonyl chloride; S6. The laser operation mechanism is activated, and the laser emits a laser beam. After being adjusted by the beam shaping unit and the scanning mirror, it irradiates the initiator area, initiating the cross-linking and curing reaction of the phenolic resin and furfuryl alcohol, accelerating the induction period, and promoting the rapid polymerization of the organic matter. The laser operation is completed after a period of irradiation. S7. Repeat steps S4 to S7 until the program ends, completing the printing and obtaining the alumina ceramic preform.

[0034] Example 4 A method for preparing an aluminum nitride ceramic preform is provided, wherein the method adopts the laser-assisted gel-molding additive manufacturing device of the present invention for preparation; the laser power is 10-50W, and the scanning speed is 1000-1600mm / s, and the method specifically comprises the following steps: S1. Prepare a ceramic slurry; mix an organic monomer, a crosslinking agent, and a solvent in a certain proportion and stir to obtain a premix; wherein the organic monomer is acrylamide; the crosslinking agent is at least one of N,N'-methylenebisacrylamide and polybis(methacrylic acid); and the solvent is water; wherein the mass ratio of solvent:monomer:crosslinking agent is (10-40):(1-5):(0.05-0.25), and the solvent accounts for 10-30% of the total mass of the aluminum nitride ceramic powder; Ceramic powder and dispersant are added to the premixed solution, ball-milled for 1 to 5 hours, and then vacuum-degassed to obtain a ceramic slurry; wherein the ceramic powder is aluminum nitride ceramic powder; the dispersant is at least one of polyethyleneimine (PEI) and polyammonium acrylate (PAA-NH4), and the dispersant accounts for 2.5% of the weight of the aluminum nitride ceramic powder; S2. The ceramic slurry prepared in step S1 is poured into the storage tank; S3. Seal the laser-assisted gel-forming additive manufacturing device, evacuate the device, and maintain the vacuum environment or fill it with an inert gas; S4. Lower the forming tank by 50-200 μm and the storage tank by 120 μm. Use a scraper to scrape the ceramic slurry from the storage tank and spread it into the forming tank. Then return the scraper to its original position. S5. Start the jetting unit, the print head starts from the standby position, sprays the initiator or curing agent along a specific path, and after the jetting is completed, the print head returns to the standby position; The initiator or curing agent is ammonium persulfate or azo initiator; S6. The laser operation mechanism is activated, and the laser emits a laser beam, which is adjusted by the beam shaping unit and the scanning mirror and then irradiated to the initiator area, accelerating the induction period and promoting the rapid polymerization of the organic matter. The laser operation is completed after a period of irradiation. S7. Repeat steps S4 to S7 until the program ends, completing the printing and obtaining the aluminum nitride ceramic preform.

[0035] Example 5 A method for preparing a silicon carbide ceramic preform is provided, wherein the method adopts the laser-assisted gel-molding additive manufacturing device of the present invention for preparation; the laser power of the laser is 10-50W, and the scanning speed is 1000-1600mm / s, and the method specifically comprises the following steps: S1. Prepare a ceramic slurry; mix an organic monomer, a crosslinking agent, and a solvent in a certain proportion and stir to obtain a premix; wherein the organic monomer is acrylamide; the crosslinking agent is at least one of N,N'-methylenebisacrylamide and polybis(methacrylic acid); and the solvent is water; wherein the mass ratio of solvent:monomer:crosslinking agent is (10-40):(1-5):(0.05-0.25), and the solvent accounts for 10-30% of the total mass of the silicon carbide ceramic powder; Ceramic powder and dispersant are added to the premixed solution, ball-milled for 1 to 5 hours, and then vacuum-degassed to obtain a ceramic slurry; wherein the ceramic powder is silicon carbide ceramic powder; the dispersant is at least one of polyethyleneimine (PEI) and polyammonium acrylate (PAA-NH4), and the dispersant accounts for 2.5% of the mass of the silicon carbide ceramic powder; Steps S2 to S6 are the same as those in Example 4; S7. Repeat steps S4 to S7 until the program ends, completing the printing and obtaining a silicon carbide ceramic preform.

[0036] Brief description of the principle of the present invention: The principle of gel injection molding technology is that the initiator induces the cross-linking polymerization of organic monomers to form a three-dimensional network structure to fix special ceramic powders and form a ceramic preform of a specific shape. The technical feature is that the initiator triggers the monomer to undergo a cross-linking polymerization process after a certain induction period. This process is greatly affected by temperature, initiator concentration, monomer quantity, oxygen content, etc. Generally, the higher the temperature, the shorter the induction period. Therefore, the present invention uses laser as a heat source to shorten the induction period and improve molding efficiency. There is a certain range of correspondence between the initiator concentration and the monomer quantity. Otherwise, it is very easy to prolong the induction period or induce explosion. Oxygen is a free radical inhibitor, and a high oxygen content is not conducive to the cross-linking process. Therefore, the present invention uses a vacuum environment or an inert gas to ensure the molding quality of the preform.

[0037] The present invention aims to solve the problems of limited material resources and insufficient performance in existing additive manufacturing technologies and provides a new additive manufacturing technology. Based on the basic principle of gel injection molding technology, laser is used as a heat source to assist thermal curing molding. Specifically, it is embodied as follows: (1) Molding principle: high-solid content ceramic slurry is prepared with organic monomers, diluents, cross-linking agents, ceramic powders, etc. as raw materials. After a layer of ceramic slurry is laid at a specific height, an initiator is selectively sprayed by a nozzle, and the initiator area is sprayed in combination with laser scanning. The laser is used as a heat source to accelerate the curing process. After the molding tank drops to a specific height, the above operation is repeated to complete the additive manufacturing process; (2) Molding equipment: such as Figure 1 As shown, the basic components of the molding device include a storage tank, a molding tank, a guide rail, a lifting system, a nozzle, a scraper, a laser, etc. After the slurry is poured into the storage tank, it rises to a certain height under computer control, and the scraper moves on the guide rail to spread a layer of slurry on the molding tank. After the scraper returns to its original position, the nozzle sprays a certain amount of initiator along a specific path, and the laser irradiates the initiator area to provide heat for the organic monomer curing process. When the thermal curing process is completed, the molding tank descends to a certain height, and the above process is repeated to complete the molding process.

[0038] In summary, this invention addresses the low solids content issue in specialty ceramic preforms based on existing additive manufacturing techniques. By leveraging the fundamental principles of gelcasting, it combines conventional specialty ceramic preparation techniques with additive manufacturing, leveraging the advantages of conventional high-solids ceramic preforms with the complex shape-forming capabilities of additive manufacturing. To implement this novel additive manufacturing technology, new additive manufacturing equipment has been developed to promote its development and application in the specialty ceramics field.

[0039] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in the present disclosure can be achieved. This is not limited herein.

[0040] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A laser-assisted gel-forming additive manufacturing device, characterized in that: It includes a shell, a displacement mechanism, a material storage mechanism, a molding mechanism, an environmental control mechanism and a laser operation mechanism; The housing comprises an upper housing and a lower housing; the lower housing is provided with at least two lifting platforms to achieve independent height adjustment of objects placed on the lifting platforms; the upper housing and the lower housing are sealed in the working state; The displacement mechanism includes a first guide rail and a second guide rail; the first guide rail is installed on the side of the lower shell; the second guide rail is installed on the first guide rail and moves along the first guide rail in the horizontal X-axis direction; The storage mechanism includes a storage tank for storing special ceramic slurry; The molding mechanism includes a molding trough, a spray unit, and a scraper; the scraper is mounted on a first guide rail on the side of the lower housing and is used to spread the slurry in the storage tank into the molding trough; the molding trough is placed horizontally and is used to carry and solidify the ceramic slurry; the scraper and the print head are parallel to the molding trough; the spray unit is mounted on a second guide rail and independently moves in the horizontal Y-axis direction, and is driven by the second guide rail to move on the first guide rail; when in operation, the spray unit sprays a certain amount of initiator or curing agent into the molding trough area along a specific path; The environmental control mechanism is mounted on the upper housing and is used to control the inflow and outflow of gas to ensure the sealing of the device; The output laser of the laser operation mechanism covers the forming groove and irradiates different positions during the forming process.

2. The laser-assisted gel forming additive manufacturing device according to claim 1, characterized in that: It also includes a first limit switch and a second limit switch; the first limit switch and the second limit switch are respectively used to limit the positions of the scraper and the second guide rail on the first guide rail to prevent movement beyond the designed stroke.

3. The laser-assisted gel forming additive manufacturing device according to claim 1, characterized in that: The ejection unit includes a print head and a conduit; the print head is mounted on a second guide rail; the print head independently moves in the horizontal Y-axis direction on the second guide rail, and is driven by the second guide rail to move on the first guide rail, i.e., in the horizontal X-axis direction; the conduit is connected to a feeding device containing an initiator or a curing agent, and the initiator or curing agent is transported to the print head through the conduit, and the print head sprays a certain amount of initiator or curing agent along a specific path; the position and ejection path of the print head are controlled by a computer to ensure accurate distribution of the initiator or curing agent.

4. The laser-assisted gel forming additive manufacturing device according to claim 1, characterized in that: The lower shell is provided with two lifting platforms, which are used to place the material storage trough and the molding trough respectively, and realize independent lifting and adjusting of the height of the material storage trough and the molding trough to meet different molding requirements; a sealing gasket is installed at the connection between the upper shell and the lower shell to prevent gas leakage.

5. The laser-assisted gel forming additive manufacturing device according to claim 1, characterized in that: The laser operation mechanism includes a laser, a beam shaping unit, and a scanning mirror arranged in sequence along the optical path; the laser provides a laser source for slurry heating; the beam shaping unit collimates and shapes the laser beam emitted by the laser to improve the output beam quality; the scanning mirror is used to control the beam direction; The laser is a fiber laser, a YAG laser, a CO2 laser, or a semiconductor laser; the laser power of the laser is 5-50W, and the laser scanning rate is 800-2500mm / s.

6. The laser-assisted gel forming additive manufacturing device according to claim 5, characterized in that: The laser is a CO2 laser with a wavelength of 10.6 μm and a minimum spot size of 80-90 μm; The first guide rail and the second guide rail are in a perpendicular relationship.

7. A laser-assisted gel forming additive manufacturing method, prepared using the laser-assisted gel forming additive manufacturing device according to claim 1, characterized in that: The specific steps include: S1. The ceramic powder, organic monomer, crosslinking agent, and dispersant are mixed in a certain proportion and degassed to obtain a ceramic slurry; S2. The ceramic slurry prepared in step S1 is poured into the storage tank; S3. Seal the laser-assisted gel-forming additive manufacturing device, evacuate the device, and maintain the vacuum environment or fill it with an inert gas; S4. The molding tank and the storage tank are lowered or raised to the corresponding height, and the ceramic slurry is scraped out from the storage tank with a scraper and spread into the molding tank; the scraper then returns to its initial position; S5. Start the ejection unit, the print head starts from the standby position, and sprays the initiator or fixative along a specific path. After the ejection is completed, the print head returns to the standby position; S6. The laser operation mechanism is activated, and the laser emits a laser beam, which is adjusted by the beam shaping unit and the scanning mirror and then irradiated to the initiator area, accelerating the induction period and promoting the rapid polymerization of the organic matter. The laser operation is completed after a period of irradiation. S7. Repeat steps S4 to S7 until the program ends, completing the printing and obtaining the ceramic preform.

8. The laser-assisted gel forming additive manufacturing method according to claim 7, characterized in that: The mixing in step S1 is performed by ball milling for 1 to 5 hours, and the degassing is performed by vacuum degassing.

9. The laser-assisted gel forming additive manufacturing method according to claim 7, characterized in that: The ceramic powder includes aluminum oxide, silicon carbide, aluminum nitride, and silicon nitride; The organic monomer includes acrylamide, isobutylene maleic anhydride polymer, chitosan, agarose, methacrylamide, acrylic acid, butadiene or furfuryl alcohol; The cross-linking agent is methyl acrylate, N,N'-methylenebisacrylamide, polybismethacrylic acid or glutaraldehyde; The dispersant includes ammonium polyacrylate, ammonium citrate, ammonium polymethacrylate, sodium hexametaphosphate, and polyethylene glycol; The initiator or curing agent includes hydrogen peroxide, benzoic acid peroxide, sodium persulfate, potassium persulfate, sulfonyl chloride, ammonium persulfate or azo initiator.

10. The laser-assisted gel forming additive manufacturing method according to claim 7, characterized in that: The step S1 includes the following sub-steps: S11. The organic monomer, crosslinking agent, and solvent are mixed in a certain proportion and stirred to obtain a premixed solution; S12. Ceramic powder and dispersant are added to the premixed liquid, mixed by ball milling, and then vacuum degassing is performed to obtain a ceramic slurry.

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