Laser-assisted gel molding additive manufacturing apparatus and method

Abstract

The application relates to the technical field of ceramic material forming, in particular to a laser-assisted gel forming additive manufacturing device and method. 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 surface of the lower shell, and the second guide rail is installed on the first guide rail; the forming mechanism comprises a forming groove, a spraying 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 realize independent movement in the horizontal Y-axis direction, and is moved on the first guide rail under the driving of the second guide rail; during work, the spraying unit sprays reagents to the forming groove area according to a specific path; the environmental control mechanism ensures the sealing property of the device; and the laser operation mechanism irradiates different positions during the forming process. The prepared ceramic material has high performance of traditional materials and high complexity structure of additive manufacturing.

Description

Technical Field

[0001] This invention relates to the field of ceramic material forming technology, and in particular to a laser-assisted gel molding additive manufacturing apparatus and method. Background Technology

[0002] Gel casting is a typical advanced traditional ceramic manufacturing technology. It boasts advantages such as a wide availability of powder materials and high-performance green bodies, and is widely used in the research and production of ceramic structural components made from carbides and oxides. Typically, gel casting involves formulating organic monomers with ceramic powder to create a low-viscosity, high-solids-content ceramic slurry. Under the action of catalysts and initiators, the organic monomers undergo cross-linking polymerization to form a three-dimensional network structure, resulting in in-situ solidification and shaping of the ceramic particles. With the continuous development of aerospace, petrochemical, and rail transportation industries, there are increasing demands for functional structural ceramics, such as heatless processes, lightweight designs, and integrated constructions. This requires ceramic structural components with corresponding complex structures. Although gel casting is a near-net-shape forming technology, significant technical barriers remain when preparing highly complex structures such as extremely small curved surfaces and lattice structures.

[0003] Additive manufacturing technology, based on the principle of layer-by-layer deposition, has brought about a revolutionary technological revolution in the fabrication of highly complex ceramic structures. To date, this technology can be categorized into more than ten types, including selective laser sintering, binder spraying, and photopolymerization, enabling the fabrication of materials with arbitrary structures. However, additive manufacturing technology has specific requirements for powders. For example, photopolymerization technology struggles to produce high-solids-content preforms when preparing high-absorbency carbide or nitride ceramics. Furthermore, the performance of ceramic materials currently prepared using additive manufacturing technology is significantly lower than that prepared using traditional techniques. Despite the clear technological advantages of additive manufacturing in fabricating complex ceramic structures, limitations in powder availability and poor preform performance restrict its development and application.

[0004] Existing additive manufacturing technologies can be categorized into powder bed molding and ceramic slurry molding based on the raw material form. Typical powder bed molding technologies include selective laser sintering (SLS) and binder jetting (BJP), while representative ceramic slurry molding technologies include photopolymerization (SLA / DLP). Due to the limited packing density of powders, it is difficult to obtain high-solids preforms. Therefore, ceramic slurry molding technology is more advantageous for preparing high-solids-content ceramic preforms. However, photopolymerization requires high light penetration depth in the slurry, and currently faces the challenge of simultaneously achieving high penetration depth and high solids content (usually below 50%), especially for high-absorbency ceramic materials such as silicon carbide and silicon nitride. Summary of the Invention

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

[0006] The primary objective of this invention is to provide a laser-assisted gel molding additive manufacturing apparatus, comprising a housing, a displacement mechanism, a material storage mechanism, a molding mechanism, an environmental control mechanism, and a laser operation mechanism; The housing includes 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 housing; 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 tank, a spraying 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 tank. The molding tank is placed horizontally and is used to support and cure the ceramic slurry. The scraper and the printing nozzle are both parallel to the molding tank. The spraying unit is mounted on a second guide rail and can move independently in the horizontal Y-axis direction. It can also move on the first guide rail under the drive of the second guide rail. During operation, the spraying unit sprays a certain amount of initiator or curing agent into the molding tank area according to a specific path. The environmental control mechanism is installed on the upper housing and is used to control the inflow and outflow of gas to ensure the airtightness of the device; The laser output of the laser working 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 position of the scraper and the second guide rail on the first guide rail, respectively, to prevent movement from exceeding the designed stroke.

[0008] Preferably, the spraying unit includes a print head and a conduit; the print head is mounted on a second guide rail; the print head can move independently on the second guide rail in the horizontal Y-axis direction, and under the drive of the second guide rail, it can 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 curing agent, and the initiator or curing agent is delivered 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 spraying path of the print head are controlled by a computer to ensure the precise distribution of the initiator or curing agent.

[0009] Preferably, the lower housing is provided with two lifting platforms, which are used to place the storage tank and the forming tank respectively, and the height of the storage tank and the forming tank can be independently adjusted to meet different forming requirements; a sealing gasket is installed at the connection between the upper housing and the lower housing to prevent gas leakage.

[0010] Preferably, the laser operating mechanism includes a laser, a beam shaping unit, and a scanning mirror arranged sequentially along the optical path; the laser provides a laser source for heating the slurry; the beam shaping unit collimates and shapes the laser beam emitted by the laser to improve the quality of the output beam; and the scanning mirror is used to control the beam direction. The laser is a fiber laser, YAG laser, CO2 laser, or 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 perpendicular to each other.

[0012] The second objective of this invention is to provide a laser-assisted gel molding additive manufacturing method, which uses the aforementioned laser-assisted gel molding additive manufacturing apparatus for preparation, and specifically includes the following steps: S1. Ceramic powder, organic monomer, crosslinking agent and dispersant are mixed in a certain proportion and degassed to obtain ceramic slurry; S2. Pour the ceramic slurry prepared in step S1 into the storage tank; S3. Seal the laser-assisted gel molding additive manufacturing device, maintain a vacuum environment after evacuation, or fill it with inert gas; S4. Lower or raise the forming tank and the storage tank to the corresponding heights respectively, and use a scraper to scrape the ceramic slurry from the storage tank and spread it evenly into the forming tank; then the scraper returns to its initial position; S5. Start the jetting unit. The print head starts from the standby position and jets the initiator or fixative along a specific path. After jetting is completed, the print head returns to the standby position. S6. Start the laser operation mechanism. The laser emits a laser beam, which is adjusted by the beam shaping unit and scanning mirror and then irradiates the initiator area to accelerate the induction period and promote the rapid polymerization of organic matter. One laser operation is completed after irradiation for a period of time. S7. Repeat steps S4 to S7 until the program ends, complete the printing, and obtain the ceramic preform.

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

[0014] Preferably, the ceramic powder includes alumina, silicon carbide, aluminum nitride, and silicon nitride; The organic monomers include acrylamide, isobutylene maleic anhydride polymer, chitosan, agarose, methacrylamide, acrylic acid, butadiene, or furfuryl alcohol; The crosslinking agent is methyl acrylate, N,N'-methylenebisacrylamide, polydimethacrylate 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, benzyl chloride, ammonium persulfate, or azo initiators.

[0015] Preferably, step S1 includes the following sub-steps: S11. Mix the organic monomer, crosslinking agent, and solvent in a certain proportion and stir to obtain a premixed solution; S12. Add ceramic powder and dispersant to the premixed liquid, ball mill and mix, then degas under vacuum to obtain ceramic slurry.

[0016] Compared with the prior art, the present invention can achieve the following beneficial effects: This invention addresses the problem of low solid content in special ceramic preforms based on existing additive manufacturing technologies. It combines traditional special ceramic preparation techniques with additive manufacturing, utilizing the fundamental principles of gel casting. This fully leverages the advantages of high solid content in traditional ceramic preforms with the complex shape-forming capabilities of additive manufacturing. The invention provides a manufacturing method using a high-solid-content ceramic slurry (above 65%) formed by gel casting, assisted by laser heat source for thermosetting, thus solving the problem of difficult photocuring of ceramic slurries in existing additive manufacturing. Simultaneously, the powder particle composition in the slurry can be controlled to optimize material properties. Ceramics prepared using the laser-assisted gel casting additive manufacturing device and method of this invention possess the advantages of high material properties from traditional methods, while also exhibiting the advantages of highly complex structures found in additive manufacturing ceramics. By fully utilizing the advantages of both technologies, high-performance preparation of complex-structured ceramics can be achieved, which is of great significance for broadening the application range of special ceramics or extending their service life. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the laser-assisted gel molding additive manufacturing apparatus provided in an embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram of the internal structure of the laser operation mechanism of the laser-assisted gel molding additive manufacturing apparatus provided in an embodiment of the present invention.

[0019] Figure 3This is a flowchart of a laser-assisted gel molding additive manufacturing method according to an embodiment of the present invention.

[0020] Figure label: 1. Inflation valve; 2. Butterfly valve; 3. Scraper; 4. Storage tank; 5. First guide rail; 6. First limit switch; 7. Second limit switch; 8. Forming groove; 9. Printer head; 10. Catheter; 11. Second guide rail; 12. Upper shell; 13. Lower shell; 14. Laser operation mechanism; 141. Laser; 142. Beam shaping unit; 143. Scanning mirror; 144. Laser beam. Detailed Implementation

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

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0023] This invention provides a laser-assisted gel molding additive manufacturing apparatus for preparing special ceramic preforms using gel injection molding technology. The apparatus has good sealing properties to achieve a vacuum or inert gas environment; see also... Figures 1-2 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. All parts work 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, which can independently adjust the height of objects placed on the lifting platforms; specifically, two lifting platforms are provided, which are respectively used to place the storage tank 4 and the forming tank 8, and the heights of the storage tank 4 and the forming tank 8 can be independently adjusted to adapt to 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 consists of a closed-loop control unit composed 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 instructions on layer height, liquid level or process parameters 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 housing 13; the second guide rail 11 (secondary guide rail) is installed on the first guide rail 5 by a bracket, and the second guide rail 11 moves along the first guide rail 5 in the horizontal X-axis direction, and the first guide rail 5 and the second guide rail 11 are perpendicular to each other.

[0025] The storage mechanism includes a storage tank 4 for storing special ceramic slurry; The molding mechanism includes a molding trough 8, a spraying 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 scraper 3 moves on the first guide rail 5 under the precise control of the computer. It is used to spread the slurry in the storage tank 4 into the molding tank 8 to ensure the uniform distribution of the slurry. The spraying 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 move independently along the horizontal Y-axis on the second guide rail 11, and can also move along the first guide rail 5 (horizontal X-axis movement) driven by the second guide rail 11. The conduit 10 is connected to a feeding device containing reagents such as initiators or curing agents. The initiator or curing agent is delivered to the print head 9 through the conduit 10. The print head 9 sprays a certain amount of initiator or curing agent into the forming tank 8 area according to a specific path. The position and spraying path of the print head 9 are controlled by a computer to ensure the precise distribution of the initiator or curing agent. The molding tank 8 is placed horizontally to hold and cure the ceramic slurry; the scraper 3 and the printing nozzle 9 are both parallel to the molding tank 8 to ensure uniform distribution of the slurry and precise spraying of the initiator (or curing agent); The storage tank 4 and the forming tank 8 are respectively placed on two independent lifting platforms of the lower housing 13. When ready to work, the lifting platforms lower or raise the forming tank 8 and the storage tank 4 to the corresponding heights respectively.

[0026] The environmental control mechanism includes an inflation valve 1 and a butterfly valve 2 mounted on the upper housing 12, used to control the inflow and outflow of gas and ensure the airtightness of the entire device. The inflation valve 1 is used to inject inert gas into the working area to remove 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 housing 12 by fasteners such as bolts and nuts to ensure tight contact between the valve and the housing, thereby achieving a good sealing effect.

[0027] like Figure 2 As shown, the laser processing mechanism 14 includes a laser 141, a beam shaping unit 142, and a scanning mirror 143 arranged sequentially along the optical path. The laser 141 provides a laser source for heating the slurry 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 directly heats the printing area as the output laser. The laser processing mechanism 14 is installed in a position that ensures that its beam can cover the entire area of ​​the molding tank 8, so as to irradiate the initiator at different positions during the molding process. Specifically, the laser power of the laser working mechanism 14 is 10~50W and the laser scanning rate is 1000~1600mm / s; the design of the laser working mechanism 14 ensures that the laser can be uniformly irradiated to the initiator area, thereby accelerating the curing process and improving the molding efficiency. Laser 141 can be a fiber laser, YAG laser, CO2 laser, semiconductor laser, etc., and its specific type can be selected according to actual needs; preferably, a CO2 laser with a wavelength of 10.6μm and a minimum spot size of 80~90μm is preferred.

[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 used to limit the position of the scraper 3 and the second guide rail 11 on the first guide rail 5, respectively, to prevent the components from moving beyond their designed stroke and to avoid impact or damage to the equipment.

[0029] This invention also provides a laser-assisted gel molding additive manufacturing method, namely a method for preparing a ceramic preform; the method uses the laser-assisted gel molding additive manufacturing apparatus of this invention for preparation, and specifically includes the following steps: S1. Preparation of ceramic slurry: Ceramic powder, organic monomer, crosslinking agent and dispersant are mixed in a certain proportion and degassed to obtain ceramic slurry; Specifically, the ceramic powder includes, but is not limited to, alumina, silicon carbide, and aluminum nitride; the organic monomers include, but are not limited to, acrylamide, isobutylene maleic anhydride polymer, chitosan, agarose, methacrylamide, acrylic acid, butadiene, and furfuryl alcohol; the crosslinking agents are methyl acrylate, N,N'-methylenebisacrylamide, polydimethicone, or glutaraldehyde; and the dispersants include, but are not limited to, ammonium polyacrylate, ammonium citrate, ammonium polymethacrylate, sodium hexametaphosphate, and polyethylene glycol. Specifically, the mixing process involves ball milling for 1-5 hours, and degassing is performed using vacuum degassing. Specifically, it includes the following sub-steps: S11. Mix the organic monomer, crosslinking agent, and solvent in a certain proportion and stir to obtain a premixed solution; S12. Add ceramic powder and dispersant to the premixed liquid, ball mill and mix, then degas under vacuum to obtain ceramic slurry; S2. Pour the ceramic slurry prepared in step S1 into the storage tank; S3. Seal the laser-assisted gel molding additive manufacturing device, maintain a vacuum environment after evacuation, or fill it with inert gas; S4. Lower or raise the molding tank and the storage tank to the corresponding heights respectively, and use a scraper to scrape the ceramic slurry from the storage tank and spread it evenly into the molding tank; S5. Start the jetting unit. The print head starts from the standby position and jets the initiator or fixative along a specific path. After jetting is completed, the print head returns to the standby position. The initiators include, but are not limited to, hydrogen peroxide, benzoic acid peroxide, sodium persulfate, potassium persulfate, etc. S6. Start the laser operation mechanism. The laser emits a laser beam, which is adjusted by the beam shaping unit and scanning mirror and then irradiates the initiator area to accelerate the induction period and promote the rapid polymerization of organic matter. One laser operation is completed after irradiation for a period of time. S7. Repeat steps S4 to S7 until the program ends, complete the printing, and obtain the ceramic preform.

[0030] The ceramic preform forming principle of the present invention includes: (1) cross-linking and curing of organic monomers under the action of initiators, catalysts, etc., and the curing rate is accelerated by laser heat source; (2) organic monomers themselves have cross-linking activity and undergo a self-curing process under the action of laser heat source. Specific embodiments will be listed below for further explanation.

[0031] Example 1 A method for preparing a silicon nitride ceramic preform, comprising the use of the laser-assisted gel molding additive manufacturing apparatus of this invention; the laser used is a carbon dioxide laser with a laser power of 5~20W, a scanning speed of 800~2500mm / s, and a scanning spacing of 0.1~0.3mm; specifically including the following steps: S1. Preparation of ceramic slurry: S11. Mix the organic monomer, crosslinking agent, and solvent in a certain proportion and stir to obtain a premixed solution; wherein the organic monomer is furfuryl alcohol; the crosslinking agent is phenolic resin; the solvent is ethylene glycol; the mass ratio of ethylene glycol:furfuryl alcohol:phenolic resin is 2:1:1, and the ethylene glycol accounts for 10-30% of the total mass of silicon nitride ceramic powder. S12. Add ceramic powder and dispersant to the above premixed liquid, ball mill and mix for 2 hours, then degas under vacuum to obtain ceramic slurry; wherein the ceramic powder is silicon nitride ceramic powder; the dispersant is one or more of polyammonium methacrylate, sodium hexametaphosphate, and polyethylene glycol, and the dispersant accounts for 1-3% of the mass of silicon nitride ceramic powder; S2. Pour the ceramic slurry prepared in step S1 into the storage tank; S3. Seal the laser-assisted gel molding additive manufacturing device, maintain a vacuum environment after evacuation, or fill it with inert gas; S4. Lower the forming tank by 100μm, raise the storage tank, and use a scraper to scrape the ceramic slurry from the storage tank and spread it evenly into the forming tank; then the scraper returns to its initial position; S5. Start the jetting unit. The print head starts from the standby position and jets the initiator along a specific path. After jetting is completed, the print head returns to the standby position. The initiators include, but are not limited to, hydrogen peroxide, benzoic acid peroxide, sodium persulfate, potassium persulfate, etc. S6. Start the laser operation mechanism. The laser emits a laser beam, which is adjusted by the beam shaping unit and scanning mirror and then irradiates the initiator area to initiate the cross-linking and curing reaction of phenolic resin and furfuryl alcohol, accelerates the induction period, and promotes the rapid polymerization of organic matter. One laser operation is completed after irradiation for a period of time. S7. Repeat steps S4 to S7 until the program ends, complete the printing, and obtain the silicon nitride ceramic preform.

[0032] Example 2 A method for preparing a silicon carbide ceramic preform, using the laser-assisted gel molding additive manufacturing apparatus of this invention, specifically includes the following steps: S1. Prepare ceramic slurry; mix organic monomers, crosslinking agents, and solvents in a certain proportion and stir to obtain a premixed liquid; wherein the organic monomer is furfuryl alcohol; the crosslinking agent is phenolic resin; the solvent is ethylene glycol; the mass ratio of ethylene glycol:furfuryl alcohol:phenolic resin is 2:1:1, and the ethylene glycol accounts for 10~30% of the total mass of silicon carbide ceramic powder; Ceramic powder and dispersant were added to the above premixed liquid, and the mixture was ball-milled for 1-5 hours. Vacuum degassing was then performed to obtain a ceramic slurry. The ceramic powder was silicon carbide ceramic powder, and the dispersant was polyethylene glycol PEG400, accounting for 2.5% of the mass of the silicon carbide ceramic powder. S2. Pour the ceramic slurry prepared in step S1 into the storage tank; S3. Seal the laser-assisted gel molding additive manufacturing device, maintain a vacuum environment after evacuation, or fill it with inert gas; S4. Lower the forming tank by 50~200μm and raise the storage tank by 80μm. Use a scraper to scrape the ceramic slurry from the storage tank and spread it evenly into the forming tank; then the scraper returns to its initial position. S5. Start the spraying unit. The print head starts from the standby position and sprays the initiator or curing agent along a specific path. After spraying 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.; the curing agent is benzyl chloride; S6. Start the laser operation mechanism. The laser emits a laser beam, which is adjusted by the beam shaping unit and scanning mirror and then irradiates the initiator area to initiate the cross-linking and curing reaction of phenolic resin and furfuryl alcohol, accelerates the induction period, and promotes the rapid polymerization of organic matter. One laser operation is completed after irradiation for a period of time. S7. Repeat steps S4 to S7 until the program ends, complete the printing, and obtain the silicon carbide ceramic preform.

[0033] Example 3 A method for preparing an alumina ceramic preform, using the laser-assisted gel molding additive manufacturing apparatus of this invention; the laser power is 10~50W, and the scanning speed is 1000~1600mm / s, specifically including the following steps: S1. Prepare ceramic slurry; mix organic monomers, crosslinking agents, and solvents in a certain proportion and stir to obtain a premixed liquid; wherein the organic monomer is furfuryl alcohol; the crosslinking agent is phenolic resin; the solvent is ethylene glycol; the mass ratio of ethylene glycol:furfuryl alcohol:phenolic resin is 2:1:1, and the ethylene glycol accounts for 10~30% of the total mass of alumina ceramic powder; Ceramic powder and dispersant were added to the above premixed liquid, and the mixture was ball-milled for 1-5 hours. Vacuum degassing was then performed to obtain a ceramic slurry. The ceramic powder was alumina ceramic powder, and the dispersant was polyethylene glycol PEG400, accounting for 2.5% of the mass of the alumina ceramic powder. S2. Pour the ceramic slurry prepared in step S1 into the storage tank; S3. Seal the laser-assisted gel molding additive manufacturing device, maintain a vacuum environment after evacuation, or fill it with inert gas; S4. Lower the forming tank by 50~200μm and raise the storage tank by 80μm. Use a scraper to scrape the ceramic slurry from the storage tank and spread it evenly into the forming tank; then the scraper returns to its initial position. S5. Start the spraying unit. The print head starts from the standby position and sprays the initiator or curing agent along a specific path. After spraying is completed, the print head returns to the standby position. The initiator or curing agent is benzyl chloride; S6. Start the laser operation mechanism. The laser emits a laser beam, which is adjusted by the beam shaping unit and scanning mirror and then irradiates the initiator area to initiate the cross-linking and curing reaction of phenolic resin and furfuryl alcohol, accelerates the induction period, and promotes the rapid polymerization of organic matter. One laser operation is completed after irradiation for a period of time. S7. Repeat steps S4 to S7 until the program ends, complete the printing, and obtain the alumina ceramic preform.

[0034] Example 4 A method for preparing an aluminum nitride ceramic preform, using the laser-assisted gel molding additive manufacturing apparatus of this invention; the laser power is 10~50W, and the scanning speed is 1000~1600mm / s, specifically including the following steps: S1. Prepare ceramic slurry; mix organic monomer, crosslinking agent, and solvent in a certain proportion and stir to obtain a premixed liquid; wherein the organic monomer is acrylamide; the crosslinking agent is at least one of N,N'-methylenebisacrylamide and polydimethicone; 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 is 10~30% of the total mass of aluminum nitride ceramic powder; Ceramic powder and dispersant were added to the above premixed liquid, and the mixture was ball-milled for 1-5 hours. After vacuum degassing, a ceramic slurry was obtained. The ceramic powder was aluminum nitride ceramic powder, and the dispersant was at least one of polyvinyl ammonium (PEI) and polyammonium polyacrylate (PAA-NH4), accounting for 2.5% of the mass of the aluminum nitride ceramic powder. S2. Pour the ceramic slurry prepared in step S1 into the storage tank; S3. Seal the laser-assisted gel molding additive manufacturing device, maintain a vacuum environment after evacuation, or fill it with inert gas; S4. Lower the forming tank by 50~200μm and raise the storage tank by 120μm. Use a scraper to scrape the ceramic slurry from the storage tank and spread it evenly into the forming tank; then the scraper returns to its initial position. S5. Start the spraying unit. The print head starts from the standby position and sprays the initiator or curing agent along a specific path. After spraying is completed, the print head returns to the standby position. The initiator or curing agent is ammonium persulfate or azo initiator; S6. Start the laser operation mechanism. The laser emits a laser beam, which is adjusted by the beam shaping unit and scanning mirror and then irradiates the initiator area to accelerate the induction period and promote the rapid polymerization of organic matter. One laser operation is completed after irradiation for a period of time. S7. Repeat steps S4 to S7 until the program ends, complete the printing, and obtain the aluminum nitride ceramic preform.

[0035] Example 5 A method for preparing a silicon carbide ceramic preform, using the laser-assisted gel molding additive manufacturing apparatus of this invention; the laser power is 10~50W, and the scanning speed is 1000~1600mm / s, specifically including the following steps: S1. Prepare ceramic slurry; mix organic monomer, crosslinking agent, and solvent in a certain proportion and stir to obtain a premixed liquid; wherein the organic monomer is acrylamide; the crosslinking agent is at least one of N,N'-methylenebisacrylamide and polydimethicone; 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 is 10~30% of the total mass of silicon carbide ceramic powder; Ceramic powder and dispersant are added to the above premixed liquid, and the mixture is ball-milled for 1-5 hours. After vacuum degassing, a ceramic slurry is obtained. The ceramic powder is silicon carbide ceramic powder, and the dispersant is at least one of polyethyleneimine (PEI) and ammonium polyacrylate (PAA-NH4), accounting for 2.5% of the mass of the silicon carbide ceramic powder. Steps S2 to S6 are the same as in Example 4; S7. Repeat steps S4 to S7 until the program ends, complete the printing, and obtain the silicon carbide ceramic preform.

[0036] Brief Description of the Invention: The principle of gel casting technology lies in the initiator inducing the cross-linking polymerization of organic monomers to form a three-dimensional network structure, thereby fixing special ceramic powder and forming a ceramic preform of a specific shape. The key technical feature is that the initiator initiates the cross-linking polymerization of monomers after a certain induction period. This process is significantly affected by temperature, initiator concentration, monomer quantity, and oxygen content. Generally, higher temperatures result in a shorter induction period. Therefore, this invention uses a laser as a heat source to shorten the induction period and improve molding efficiency. Furthermore, there is a certain correlation between initiator concentration and monomer quantity; otherwise, the induction period can easily be prolonged or explosive polymerization may occur. Oxygen is a free radical inhibitor, and high oxygen content is detrimental to the cross-linking process. Therefore, this invention employs a vacuum environment or inert gas to ensure the quality of the preform molding.

[0037] This invention addresses the limitations of existing additive manufacturing technologies in terms of material availability and performance deficiencies by providing a novel additive manufacturing technology. Based on the fundamental principles of gel casting technology, it utilizes a laser as a heat source to assist in thermosetting. Specifically, it includes: (1) Molding principle: A high-solids-content ceramic slurry is prepared using organic monomers, diluents, crosslinking agents, ceramic powder, etc. After a layer of ceramic slurry is laid at a specific height, an initiator is selectively sprayed using a nozzle, combined with laser scanning of the initiator area. The laser acts as a heat source to accelerate the curing process. After the molding tank descends 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, and a laser. After the slurry is poured into the storage tank, under computer control, the storage tank rises to a certain height. The scraper moves on the guide rail to spread a layer of slurry in the molding tank. After the scraper returns to its original position, the nozzle sprays a certain amount of initiator along a specific path. The laser irradiates the initiator area to provide heat for the curing process of the organic monomer. After 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 problem of low solid content in special ceramic preforms based on existing additive manufacturing technologies. It combines traditional special ceramic preparation techniques with additive manufacturing technology, utilizing the fundamental principles of gel casting. This fully leverages the high solid content advantage of traditional ceramic preforms with the complex shape-forming capabilities of additive manufacturing. To realize this novel additive manufacturing technology, new additive manufacturing equipment is developed to promote its development and application in the field of special ceramics.

[0039] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0040] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A laser-assisted gel molding additive manufacturing apparatus, characterized in that: It includes a housing, a displacement mechanism, a material storage mechanism, a forming mechanism, an environmental control mechanism, and a laser operation mechanism; The housing includes 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 housing; 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 tank, a spraying 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 tank. The molding tank is placed horizontally and is used to support and cure the ceramic slurry. The scraper and the printing nozzle are both parallel to the molding tank. The spraying unit is mounted on a second guide rail and can move independently in the horizontal Y-axis direction. It can also move on the first guide rail under the drive of the second guide rail. During operation, the spraying unit sprays a certain amount of initiator or curing agent into the molding tank area according to a specific path. The environmental control mechanism is installed on the upper housing and is used to control the inflow and outflow of gas to ensure the airtightness of the device; The laser output of the laser working mechanism covers the forming groove and irradiates different positions during the forming process.

2. The laser-assisted gel molding additive manufacturing apparatus 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 used to limit the position of the scraper and the second guide rail on the first guide rail, respectively, to prevent movement from exceeding the designed stroke.

3. The laser-assisted gel molding additive manufacturing apparatus according to claim 1, characterized in that: The spraying unit includes a print head and a conduit; the print head is mounted on a second guide rail; the print head can move independently along the horizontal Y-axis on the second guide rail, and under the drive of the second guide rail, it can move along the first guide rail, i.e., along the horizontal X-axis; the conduit is connected to a feeding device containing an initiator or curing agent, and the initiator or curing agent is delivered 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 spraying path of the print head are controlled by a computer to ensure the precise distribution of the initiator or curing agent.

4. The laser-assisted gel molding additive manufacturing apparatus according to claim 1, characterized in that: The lower housing is equipped with two lifting platforms, which are used to place the storage tank and the forming tank respectively, and allow for independent height adjustment of the storage tank and the forming tank to adapt to different forming requirements; a sealing gasket is installed at the connection between the upper housing and the lower housing to prevent gas leakage.

5. The laser-assisted gel molding additive manufacturing apparatus according to claim 1, characterized in that: The laser operating mechanism includes a laser, a beam shaping unit, and a scanning mirror arranged sequentially along the optical path; the laser provides a laser source for heating the slurry; the beam shaping unit collimates and shapes the laser beam emitted by the laser to improve the quality of the output beam; and the scanning mirror is used to control the beam direction. The laser is a fiber laser, YAG laser, CO2 laser, or 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 molding additive manufacturing apparatus 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 perpendicular to each other.

7. A laser-assisted gel molding additive manufacturing method, comprising using the laser-assisted gel molding additive manufacturing apparatus of claim 1, characterized in that: Specifically, the steps include the following: S1. Ceramic powder, organic monomer, crosslinking agent and dispersant are mixed in a certain proportion and degassed to obtain ceramic slurry; S2. Pour the ceramic slurry prepared in step S1 into the storage tank; S3. Seal the laser-assisted gel molding additive manufacturing device, maintain a vacuum environment after evacuation, or fill it with inert gas; S4. Lower or raise the forming tank and the storage tank to the corresponding heights respectively, and use a scraper to scrape the ceramic slurry from the storage tank and spread it evenly into the forming tank; then the scraper returns to its initial position; S5. Start the jetting unit. The print head starts from the standby position and jets the initiator or fixative along a specific path. After jetting is completed, the print head returns to the standby position. S6. Start the laser operation mechanism. The laser emits a laser beam, which is adjusted by the beam shaping unit and scanning mirror and then irradiates the initiator area to accelerate the induction period and promote the rapid polymerization of organic matter. One laser operation is completed after irradiation for a period of time. S7. Repeat steps S4 to S7 until the program ends, complete the printing, and obtain the ceramic preform.

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

9. The laser-assisted gel molding additive manufacturing method according to claim 7, characterized in that: The ceramic powder includes alumina, silicon carbide, aluminum nitride, and silicon nitride; The organic monomers include acrylamide, isobutylene maleic anhydride polymer, chitosan, agarose, methacrylamide, acrylic acid, butadiene, or furfuryl alcohol; The crosslinking agent is methyl acrylate, N,N'-methylenebisacrylamide, polydimethacrylate 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, benzyl chloride, ammonium persulfate, or azo initiators.

10. The laser-assisted gel molding additive manufacturing method according to claim 7, characterized in that: Step S1 includes the following sub-steps: S11. Mix the organic monomer, crosslinking agent, and solvent in a certain proportion and stir to obtain a premixed solution; S12. Add ceramic powder and dispersant to the premixed liquid, ball mill and mix, then degas under vacuum to obtain ceramic slurry.

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