3D Printing Process for Silicon Carbide Ceramic Matrix Composites

Abstract

This invention discloses a 3D printing process for silicon carbide ceramic matrix composite materials that enables simultaneous printing, powder cleaning, and part removal during the 3D printing process. The process includes steps S1: selecting SiC powder and a binder; S2: preparing composite powder; S3: printing a SiC ceramic preform; and S4: densifying the SiC ceramic preform using vacuum debinding and PIP impregnation pyrolysis processes. A 3D printing laser sintering system is employed in step S3. This process enables rapid preparation of silicon carbide ceramic matrix composite materials, improving preparation efficiency and reducing production costs.

Description

Technical Field

[0001] This invention relates to the field of composite material preparation, and in particular to a process for preparing 3D printed silicon carbide ceramic matrix composite materials. Background Technology

[0002] With the development of the aerospace industry, there is an urgent need for advanced materials that can meet the requirements of high-temperature working environments. Silicon carbide ceramic matrix composites, with their excellent physical and chemical properties, are among the preferred materials for new structural ceramics. Silicon carbide ceramics possess excellent characteristics such as high melting point, high hardness, high wear resistance, oxidation resistance, thermal shock resistance, low coefficient of thermal expansion, high thermal conductivity, and low density. They are increasingly valued and applied in aerospace (rocket launchers, turbine blades, and bearings), military industry (vehicle armor), and chemical industry (sealing elements, carburetors).

[0003] However, silicon carbide, as a typical covalent compound, presents numerous challenges in its forming, sintering, and processing due to its high hardness, brittleness, and difficulty in sintering. Traditional forming methods for silicon carbide ceramics include dry pressing, isostatic pressing, slip casting, and extrusion, while newer methods include gel casting and direct solidification casting. These forming methods typically require molds, which have drawbacks such as difficulty in forming large and complex structures, high processing costs, and long processing cycles, significantly limiting the application of silicon carbide ceramics. Common sintering methods for silicon carbide ceramics include pressureless sintering, reaction sintering, and hot pressing, which present a series of problems such as high sintering temperatures, the need for sintering aids, stringent equipment requirements, and easy deformation of the formed parts.

[0004] 3D printing technology is a novel forming method. Unlike traditional subtractive manufacturing, it can directly form three-dimensional structures from computer-generated models by adding layers one by one. 3D printing not only eliminates the need for mold making, significantly shortening the manufacturing cycle, but also successfully overcomes the limitations of traditional processing techniques for forming complex specimens, making it particularly suitable for processing complex structural specimens. Currently, 3D printing technology is relatively mature and widely used in the manufacture of metal and polymer parts; however, using this technology to manufacture ceramic specimens still faces many challenges, such as high porosity, poor material uniformity, and low mechanical properties in the formed specimens.

[0005] Organic precursor impregnation pyrolysis (PIP) technology involves impregnating a ceramic precursor into the interior of a reinforcement, followed by pyrolysis at a set temperature and atmosphere to obtain a densified ceramic matrix composite. Densification of the ceramic matrix composite can be achieved through multiple precursor impregnation pyrolysis processes. The PIP method offers significant advantages in terms of saving material preparation time, reducing sintering temperature, and lowering manufacturing costs.

[0006] In the preparation of silicon carbide ceramic matrix composites, the molding process and densification process are crucial steps. Based on this background, this paper proposes a novel 3D printing process for preparing silicon carbide ceramic matrix composites. A silicon carbide ceramic preform is formed using 3D printing technology, and the preform is densified using PIP precursor impregnation and pyrolysis technology, achieving rapid preparation of high-performance silicon carbide ceramic matrix composites. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a 3D printing process for silicon carbide ceramic matrix composite materials that enables rapid preparation of silicon carbide ceramic matrix composite materials; and enables simultaneous printing, powder cleaning, and part removal in the 3D printing process, thereby improving the preparation efficiency of silicon carbide ceramic matrix composite materials and reducing production costs.

[0008] The technical solution adopted by this invention to solve its technical problem is: a 3D printing silicon carbide ceramic matrix composite material preparation process, including the following steps:

[0009] S1. Select SiC powder and binder;

[0010] The SiC powder is selected as a printing powder with a particle size of 10-150μm; the binder is NH4H2PO4, aluminum powder or epoxy resin;

[0011] S2. Preparation of composite powder;

[0012] Composite powder is prepared by mixing binder and SiC powder using mechanical mixing or kneading methods.

[0013] S3. Using a 3D printing laser sintering system to print SiC ceramic blanks;

[0014] The 3D printing laser sintering system includes a base; one end of the base is provided with a rotating groove; the other end of the base is provided with a powder feeding cylinder;

[0015] A circular platform is provided above one end of the base, and a first support platform is provided above the other end; a second powder cavity is provided on the circular platform;

[0016] Guide rails are provided on the circular platform and the first support platform; a powder feeding device is provided on the guide rails;

[0017] An arc-shaped gap exists between the first support platform and the circular platform; a forming cavity rotating device is provided inside the rotating groove; the forming cavity rotating device has a rotating annular platform; multiple evenly distributed forming cavities are provided on the rotating annular platform; the forming cavity rotating device enables the rotation of multiple forming cavities; the rotating annular platform, the first support platform, and the circular platform form a working platform;

[0018] An integrated processing system is installed above the rotating device of the molding cavity; the integrated processing system includes a gas protection system, a dust extraction system, and a part removal system.

[0019] The gas protection system includes a housing disposed above the working platform; the housing forms a sealed space above the working platform; the gas protection system fills the sealed space with inert gas to achieve gas protection;

[0020] The gas protection system enables dust extraction from the workpiece inside the forming cavity; the part removal system provides a part removal station for the workpiece inside the forming cavity.

[0021] A laser forming and scanning device is provided above the rotating annular platform; the laser forming and scanning device is located above the guide rail; the laser forming and scanning device is used for laser scanning of the forming cavity;

[0022] S4. The SiC ceramic blank is densified by vacuum degreasing and PIP impregnation pyrolysis process.

[0023] Furthermore, step S3, which involves printing the SiC ceramic blank using a 3D printing laser sintering system, also includes the following steps:

[0024] S31. Optimize the laser parameters and composite powder preheating temperature settings;

[0025] The laser parameter is the laser energy density; the laser energy density is optimized according to the following formula;

[0026]

[0027] In the formula: q is the laser energy density; K is the proportionality coefficient; P is the laser power; V is the laser scanning speed; and D is the scanning spacing.

[0028] The laser power in the formula is such that the powder in the scanning area is bonded together, while the powder in the non-scanning area around the scanning area is not bonded together; the laser power, laser scanning speed and scanning spacing are optimized through orthogonal experiments.

[0029] The powder preheating temperature is determined by the glass transition temperature of the resin; the powder preheating temperature is lower than the glass transition temperature; glass transition temperature - powder preheating temperature = ΔT; where ΔT is determined according to process requirements.

[0030] S32. Set the printing direction of the 3D printing laser sintering system; select vertical printing;

[0031] S33. The composite powder is loaded into the 3D printing laser sintering system, and the SiC ceramic blank is prepared by the 3D printing laser sintering system.

[0032] Furthermore, the molding cavity rotating device includes a bottom rotating ring and a top rotating ring platform;

[0033] A supporting column is provided between the bottom rotating ring and the rotating ring platform;

[0034] The rotating annular platform is provided with molding cavities evenly distributed along the circumference; a first telescopic device for adjusting the depth of the molding cavity is provided below the molding cavity.

[0035] The inner ring of the rotating annular platform matches the circular platform, and the rotation is sealed.

[0036] The outer ring of the rotating annular platform is matched with one end of the first support platform;

[0037] A sealing plate is provided below the outer ring of the rotating annular platform, which is sealed to the lower end of the housing; the sealing plate is in rotational sealing cooperation with the rotating annular platform.

[0038] The base is provided with a rotation drive device; the rotation groove is provided with an annular boss; the inner ring of the bottom rotation ring is provided with a rotation sleeve that matches the annular boss.

[0039] The rotating sleeve is fitted onto the annular boss and rotates in conjunction with the annular boss;

[0040] A gear ring is provided at the upper end of the inner cavity of the rotating sleeve; the rotation drive device is in drive cooperation with the gear ring.

[0041] Furthermore, the integrated processing system includes a housing; the housing includes a circular housing that matches the rotating ring stage and a rectangular housing that matches the first support platform; the circular housing and the rectangular housing are in communication; and the rectangular housing is sealed to the first support platform.

[0042] A powder filling box and an air suction device are provided on the top of the rectangular shell; an air supply device communicating with the inner cavity of the circular shell is provided on the top of the circular shell.

[0043] The gas supply device and the gas intake device together form a gas protection system, creating a circulating protective airflow;

[0044] The top of the circular shell is provided with a second telescopic device, a third telescopic device, a fourth telescopic device, a fifth telescopic device, and a guide cylinder; the fifth telescopic device is located in the middle of the circular shell.

[0045] The laser forming scanning device can move up and down through a fifth telescopic device;

[0046] The housing is provided with a first dust suction hood connected to the second telescopic device; a second dust suction hood connected to the third telescopic device; and a part retrieval hood connected to the fourth telescopic device.

[0047] The forming scanning mirror assembly, the first dust suction hood, the second dust suction hood, and the part removal hood each correspond to a forming cavity on the rotating annular platform;

[0048] Both the first and second dust hoods include a hood body; an annular air supply ring is provided on the top of the hood body; and an air supply pipe is provided on the annular air supply ring.

[0049] The hood is equipped with an exhaust plate that communicates with the annular air supply ring inside; the exhaust plate is equipped with evenly distributed exhaust nozzles; the lower end of the hood is equipped with an annular air intake pipe; the annular air intake pipe is equipped with an air intake nozzle; the lower end of the inner cavity of the hood is equipped with an air intake hole that communicates with the annular air intake pipe.

[0050] The top of the circular housing is provided with a first air supply device connected to the air supply pipe of the first dust hood and a second air supply device connected to the air supply pipe of the second dust hood.

[0051] A vacuum cleaner corresponding to the first and second vacuum hoods is provided at the lower end of one side of the circular shell; the vacuum cleaner has a suction pipe; the inner wall of the circular shell is provided with a nozzle groove that matches the air intake; a vacuum nozzle communicating with the suction pipe is provided at the bottom of the nozzle groove; the vacuum nozzle matches the air intake.

[0052] The second telescopic device, the third telescopic device, the first dust suction hood, the second dust suction hood, and the vacuum cleaner form a dust suction system to achieve dust suction of the workpiece inside the molding cavity;

[0053] A part-retrieving opening is provided on one side of the circular shell; sliding grooves are provided on both sides of the part-retrieving opening; a slider that seals the part-retrieving opening is installed in the sliding groove;

[0054] The part-retrieving cover has an opening on one side; a sealing cavity is provided on the side wall on both sides of the opening; a sliding groove matching the part-retrieving cover is provided inside the circular shell, and the opening matches the part-retrieving port.

[0055] The fourth telescopic device, the part-removing cover, and the part-removing port and slider provided on the circular shell form a part-removing system, providing a part-removing station for the workpiece in the forming cavity.

[0056] Furthermore, the powder feeding device includes a support frame;

[0057] A powder storage chamber is provided above the support frame; a powder spreading roller is provided inside the support frame; and a powder adding nozzle is provided above the powder storage chamber.

[0058] Both sides of one end of the support frame are provided with powder stripping blocks; a powder outlet of the powder storage chamber is provided between the two powder stripping blocks;

[0059] The other end of the support frame is provided with a slider that matches the guide rail; the slider is provided with a sliding drive device; and the powder outlet is provided with a powder quantity control device to control the amount of powder dispensed.

[0060] Furthermore, the lower end of the powder filling box is provided with a powder leakage nozzle; the lower end of the powder leakage nozzle is provided with a transverse sliding groove communicating with the powder leakage nozzle; the transverse sliding groove matches the powder filling nozzle; and a flow switch is provided inside the powder leakage nozzle.

[0061] Furthermore, the laser forming scanning device includes a support rod; a telescopic shaft is provided above one end of the support rod; and a guide column is provided above the other end.

[0062] A laser is installed at the bottom of one end of the support rod; a forming scanning mirror assembly is installed at the other end.

[0063] The telescopic shaft is driven to extend and retract via a fifth telescopic device; the guide column is slidably engaged with the guide cylinder.

[0064] A laser rangefinder is mounted on the top of the circular housing; the probe of the laser rangefinder is located directly above the support rod.

[0065] Furthermore, a powder scraper is provided on the guide rail above the gap between the circular platform and the first support platform.

[0066] Furthermore, the first telescopic device, the second telescopic device, the third telescopic device, the fourth telescopic device, and the fifth telescopic device are equipped with hydraulic cylinders or electric push rods.

[0067] Furthermore, a transparent annular cover is provided between the bottom rotating ring and the top rotating annular platform of the molding cavity rotating device.

[0068] The beneficial effects of the present invention are: the 3D printing silicon carbide ceramic matrix composite material preparation process of the present invention uses 3D printing technology to form silicon carbide ceramic blanks, and uses PIP precursor impregnation and pyrolysis technology to densify the blanks, thereby realizing the rapid preparation of high-performance silicon carbide ceramic matrix composite materials.

[0069] Secondly, in step S3, the parameters of the 3D printing laser sintering system are further optimized to ensure the forming quality of the silicon carbide ceramic matrix composite preform.

[0070] Furthermore, a 3D printing laser sintering system is used to print SiC ceramic blanks. The 3D printing laser sintering system can change the forming cavity through a forming cavity rotation device, and can also remove the workpiece by dust removal through an integrated processing system. By combining the forming cavity rotation device, the integrated processing system, and the laser forming scanning device, printing, powder cleaning, and part removal can be carried out simultaneously, thereby improving production efficiency and reducing production costs.

[0071] Finally, the 3D printing laser sintering system described in this application can realize real-time detection of laser scanning distance, which is convenient for control and ensures the forming quality of the initial blank. Attached Figure Description

[0072] Figure 1 This is a flowchart of the 3D printing process for silicon carbide ceramic matrix composite materials in an embodiment of the present invention;

[0073] Figure 2 This is an exploded schematic diagram of the 3D printing laser sintering system in an embodiment of the present invention;

[0074] Figure 3 This is a perspective view of the 3D printing laser sintering system in an embodiment of the present invention;

[0075] Figure 4 This is a front view of the 3D printing laser sintering system in an embodiment of the present invention;

[0076] Figure 5 This is a top view of the 3D printing laser sintering system in an embodiment of the present invention;

[0077] Figure 6 yes Figure 5 A-A sectional view;

[0078] Figure 7 This is a perspective view of the 3D printing laser sintering system with the shell removed in an embodiment of the present invention;

[0079] Figure 8 yes Figure 6 A magnified view of part B in the image;

[0080] Figure 9 yes Figure 6 A magnified view of part C;

[0081] Figure 10 This is a perspective view of the powder feeding device in an embodiment of the present invention;

[0082] Figure 11 This is a rear view of the powder feeding device in an embodiment of the present invention;

[0083] Figure 12 This is a side view of the powder feeding device in an embodiment of the present invention;

[0084] Figure 13 This is a perspective view of the dust hood in an embodiment of the present invention;

[0085] Figure 14 This is a schematic diagram of the structure of the dust collection hood in an embodiment of the present invention;

[0086] Figure 15 This is a perspective view of the part-removal cover in an embodiment of the present invention;

[0087] Figure 16 These are microstructure and particle size distribution diagrams of the powder in the embodiments of the present invention;

[0088] In the picture, Figure 16 (a) shows the microstructure of #600. Figure 16 (b) shows the particle size distribution of #600. Figure 16 (c) shows the microstructure of #360. Figure 16 (d) is

[0089] #360 particle size distribution Figure 16 (e) shows the microstructure of #280. Figure 16 (f) shows the particle size distribution of #280;

[0090] Figure 17 This is a particle size distribution diagram of epoxy resin E-12 powder in an embodiment of the present invention;

[0091] Figure 18 This is a schematic diagram of the impregnation and pyrolysis of the 3D-printed SiC ceramic material after degreasing in an embodiment of the present invention;

[0092] Figure 19 This is a schematic diagram showing the relationship between the weight gain, porosity, and density of the 3D-printed SiC ceramic matrix composite material and the impregnation cycle in an embodiment of the present invention.

[0093] Figure 19 Weight gain rate of SiC ceramic matrix composites printed with different PIP cycles;

[0094] Figure 19 b. Schematic diagram of porosity and density of SiC ceramic matrix composites 3D printed with different PIP cycles;

[0095] The diagram shows: 100 - base, 200 - first support platform, 300 - dust collection device, 400 - circular platform, 500 - powder feeding device, 600 - molding cavity rotation device, 700 - integrated processing system, 800 - laser forming scanning device, and 900 - dust collection hood. Detailed Implementation

[0096] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0097] Example 1

[0098] like Figure 1 As shown, the 3D printing silicon carbide ceramic matrix composite material preparation process of the present invention includes the following steps:

[0099] S1. Select SiC powder and binder;

[0100] The printing powder is selected with a particle size of 10-150μm; the binder is NH4H2PO4, aluminum powder or epoxy resin;

[0101] Based on the technical characteristics of selective laser sintering (SLS), the size and morphology of 3D printing powder affect the accuracy of the formed preform and the performance of the final ceramic specimen. Different powder particles have different microstructures and average particle sizes. If the powder particle size is too small, it is prone to agglomeration due to surface tension, and it is also prone to static electricity during the powder spreading process, sticking to the powder spreading roller and causing uneven powder thickness, which affects the quality of the formed part. If the powder particle size is too large, it will affect the surface smoothness, accuracy, and density of the formed part. Therefore, the printing powder used for selective laser sintering needs to meet good flowability and an appropriate particle size distribution of 10-150 μm to facilitate smooth powder spreading during the forming process. In this embodiment, three SiC powders with different particle sizes provided by Qingdao Yamada Abrasive Materials Co., Ltd. of Shandong Province were selected for comparative experiments. The microstructure and particle size distribution of the powders are as follows: Figure 16 As shown in Table 1.

[0102] Table 1. Particle size distribution parameters of SiC powder

[0103]

[0104] As shown in Table 1, the measured values ​​of the average particle size parameters of the three powders are distributed between 20 μm and 70 μm, which is suitable for selective laser sintering (SLS). Comparison of the microstructure and particle size distribution of the three powder sizes reveals that the selected SiC powder has an irregular geometric shape, with particle sizes in the micrometer range, and exhibits a suitable normal distribution, making it suitable for SLS forming.

[0105] Selective laser sintering of ceramic powders allows for the selection of various binders, such as NH4H2PO4, aluminum powder, and epoxy resin.

[0106] Epoxy resins, due to their active epoxy groups and highly polar hydroxyl and ether groups, possess extremely strong adhesive power, high mechanical strength, good dimensional stability, low shrinkage, low water absorption, and low preheating temperature. Specimens prepared using epoxy resin as a binder will avoid warping or cracking due to binder shrinkage during SLS molding and cooling, thus achieving high molding precision. Furthermore, during specimen preparation, the binder needs to be removed. Inorganic and metallic binders can produce harmful substances or metal residues during removal, while epoxy resin decomposes into inorganic small molecules at high temperatures and releases them in gaseous form. The small amount of pyrolytic carbon produced can also serve a connecting and supporting function. In this embodiment, bisphenol A type epoxy resin E-12 is selected as the binder, with a particle size distribution as shown below. Figure 17As shown. This binder has a small particle size and good flowability, which not only allows it to fill the spaces between silicon carbide particles evenly, facilitating powder spreading and ensuring the accuracy of the green body, but also makes it easier to remove during the subsequent degreasing process.

[0107] S2. Preparation of composite powder;

[0108] Composite powder is prepared by mixing binder and SiC powder using mechanical mixing or kneading methods.

[0109] Methods for preparing multi-component composite materials typically include mechanical mixing and kneading. Mechanical mixing involves uniformly mixing the required powder in a V-type mixer or ball mill. Generally, no phase change occurs during mixing, and the materials retain their original shape and properties. Kneading involves feeding a specific proportion of raw materials into a mixer or screw extruder; this method is complex, costly, and inefficient. Mechanical mixing, on the other hand, is simple and pollution-free; therefore, it was chosen to prepare the composite powder used in this paper.

[0110] In this embodiment, three composite powders with different particle sizes were prepared, named #600, #360, and #280, respectively. First, a certain amount of SiC micro powder was weighed and simultaneously added to a V-type mixer with an appropriate amount of epoxy resin E-12 binder. The mixture was mechanically mixed for 12 hours to ensure uniform mixing. The powder was then removed, dried, and left to use. The resulting powder was light green. Scanning electron microscopy (SEM) observation of the composite powder's microstructure showed that the mechanical mixing method effectively mixed the silicon carbide and epoxy resin E-12 powders uniformly. The epoxy resin E-12 binder was evenly distributed on and around the surface of the SiC powder particles, meeting the requirements for composite powders in selective laser sintering (SLS) 3D printing.

[0111] S3. Using a 3D printing laser sintering system to print SiC ceramic blanks;

[0112] In the selective laser sintering (SLS) process for forming silicon carbide preforms, the strength and dimensional accuracy of the specimens are related to multiple forming process parameters. Each of these parameters has a crucial impact on the quality of the formed specimen; inappropriate process parameters can lead to various defects in the specimens and even make sintering difficult. The main process parameters include: laser parameters, preheating temperature, and delamination thickness.

[0113] S31. Optimize the laser parameters, composite powder preheating temperature, and printing layer thickness.

[0114] 1. Laser parameters

[0115] As a moving heat source, the laser beam interacts with the powder for a time typically tens of milliseconds or even less, resulting in rapid heating and cooling of the powder. During heating, the powder's thermophysical properties, such as laser absorptivity, reflectivity, and thermal conductivity, change with increasing temperature, and the temperature at various points within the powder is constantly fluctuating. This constitutes a highly complex, unsteady-state heat transfer process. The primary criterion for evaluating the quality of selective laser sintering (SLS) preforms is the specimen's strength. Only with sufficient strength can preforms with complex structures be manufactured, ensuring the smooth progress of subsequent powder cleaning and post-processing. To improve preform strength, the temperature in the scanning zone during laser scanning must exceed the melting point of the epoxy resin.

[0116] For the initial blank, forming accuracy is also an important standard for measuring forming quality. Although epoxy resin has good adhesion, its low melting point results in poor blank accuracy. Laser energy density is an important parameter related to the size of the heat-affected zone. Among laser parameters, laser energy density is defined as the laser energy obtained per unit area of ​​powder, which is determined by laser power, laser beam scanning speed, and scanning spacing.

[0117] Laser energy density is expressed as:

[0118]

[0119] In the formula: q is the laser energy density; K is the proportionality coefficient; P is the laser power; V is the laser scanning speed; and D is the scanning distance. It can be seen from the formula that the laser energy density is directly proportional to the laser power, inversely proportional to the scanning speed, and inversely proportional to the scanning distance.

[0120] The laser power in the formula ensures that the powder in the scanning area adheres together, while the powder in the non-scanning areas surrounding the scanning area does not adhere together. The laser power, laser scanning speed, and scanning spacing are optimized through orthogonal experiments, as detailed below:

[0121] (1) Laser power

[0122] Laser power control is crucial. Excessive laser power leads to excessive energy, which can carbonize the epoxy resin, causing it to lose its adhesive properties. Even if the epoxy resin doesn't carbonize, the temperature field created in the laser-scanned area can cause excessive sintering in the depth direction, reducing the Z-axis accuracy of the part. It can also raise the temperature in the surrounding non-scanned areas, causing the epoxy resin to soften and bond the surrounding particles together. Horizontal distortion of the contour edges will also occur, significantly reducing the dimensional accuracy of the blank. Conversely, insufficient laser power results in insufficient energy, failing to soften the epoxy resin and preventing the powder from bonding sufficiently. Poor adhesion between layers leads to insufficient strength in the blank. Therefore, the laser power should be just right to ensure that the powder in the scanned area bonds together, while the powder in the surrounding non-scanned areas remains unbonded.

[0123] (2) Scanning speed

[0124] The scanning speed in selective laser sintering (SLS) is also a key parameter in the preform forming process, directly affecting the laser energy density and thus the preform quality. Keeping other process parameters constant, a faster laser scanning speed results in higher forming efficiency and a greater number of preforms per unit time. However, an excessively fast scanning speed means a shorter time the laser stays on a single powder layer. As calculated by the laser energy density formula, a lower laser energy density leads to a lower heating temperature for layering, less energy absorbed by the powder layer, and lower melting degree of the powder particles. This results in incomplete preform sintering, lower strength, and a tendency for powder shedding or even failure to form. Conversely, a slower scanning speed results in lower forming efficiency. Because the laser stays on the powder layer for a longer time, more energy is available for the powder to absorb, leading to more complete powder melting and a denser, stronger part. However, the scanning speed cannot be too low. An excessively low scanning speed causes energy accumulation on the powder surface, resulting in a sudden increase in local temperature, potentially leading to material "carbonization." Furthermore, a large temperature difference between the laser irradiation area and the surrounding area exacerbates warping and deformation of the part, compromising the accuracy of the preform. Therefore, the above factors need to be considered comprehensively when determining the scanning speed range of the laser.

[0125] (3) The scanning spacing, i.e., the straight-line distance between two laser scanning lines, is directly related to the laser spot diameter. An overlap coefficient is generally used. To measure, i.e., the width of the overlapping portion (D) w The percentage of the scan width (W) is shown in the following formula.

[0126]

[0127] when When the value is 0, it means that two adjacent laser scanning lines do not overlap, resulting in a weak connection between the scanning lines, or even the inability to form a continuous cross-section. When the value is 0... When the laser energy is 100, adjacent laser scanning lines completely overlap, and the laser scans repeatedly in place. The laser energy absorbed by the epoxy resin powder is far greater than the energy required for its melting, resulting in over-burning or even decomposition. To ensure a uniform laser energy distribution in the printed powder, thereby improving the microstructure and mechanical properties of the sintered part, during the laser scanning process, it is necessary to ensure that the powder in the scanning line area adheres together while controlling the temperature field formed in the scanning area.

[0128] The influence of the surrounding powder is minimized. This allows for slight overlap between two adjacent scan lines without causing adhesion or boundary phenomena between adjacent scan lines during single-layer selective laser sintering, ensuring the integrity of the adhesion of the single layer in the selective area, while reducing the influence of the temperature field of the scan area on its surrounding area, thereby ensuring the dimensional accuracy of the initial blank.

[0129] 2. Preheating temperature

[0130] Preheating temperature is also a crucial indicator determining the printing accuracy and strength of the specimen. A suitable preheating temperature provides sufficient pre-energy to the material, reducing the need for laser energy supply. Simultaneously, the preheating temperature reduces the temperature gradient between the powder in the laser scanning area and its surroundings, decreasing the temperature difference before and after molding, thus reducing warping of the sintered part and improving the dimensional accuracy of selective laser sintering (SLS) specimens. Before printing, after the powder is leveled in the printer, the preheating temperature must be controllable within a limited range. The preheating temperature should avoid being too high or too low, generally slightly lower than the glass transition temperature (Tg) of the resin. The glass transition temperature, an important thermal parameter of materials, is the temperature at which amorphous polymers transition from a highly elastic state to a glassy state or vice versa. It is also the lowest transition temperature at which the molecular chains of amorphous polymers move from a frozen state to a state of motion. Near this temperature, many thermal properties of the material undergo significant changes. When the temperature is below the glass transition temperature, the material exhibits brittleness; the molecular chains and segments are frozen and cannot move. Only the atoms (or groups) constituting the molecules vibrate in their equilibrium positions. When the temperature reaches the glass transition temperature, although the molecular chains cannot move, the chain segments begin to move, exhibiting highly elastic properties. When the temperature is above the glass transition temperature, the entire molecular chain moves, exhibiting viscous flow properties. Therefore, glass transition temperature - powder preheating temperature = ΔT; where ΔT is determined according to process requirements.

[0131] In this embodiment, only the epoxy resin undergoes a phase transition during the selective laser sintering (SLS) 3D printing process of the SiC / E-12 composite powder used. Therefore, the preheating temperature should be determined based on the glass transition temperature of epoxy resin E-12. Differential scanning calorimetry (DSC) was used to test the epoxy resin E-12. During the experiment, 11.50 mg of epoxy resin E-12 was taken, and N2 was used as a protective gas. The temperature was increased from room temperature to 300°C at a rate of 10°C / min and held at that temperature for 10 minutes. The glass transition temperature of epoxy resin E-12 is 56.17°C, and its melting range is relatively narrow. Considering the characteristics of the laboratory ambient temperature, the preheating temperature was ultimately determined to be 50°C.

[0132] 3. Layer thickness

[0133] Layer thickness refers to the height of each layer descending from the working cylinder. Selective laser sintering (SLS) involves slicing a 3D model into thin layers to obtain a series of cross-sectional contours. These contours are then used to create a 3D solid through layer-by-layer printing. Inevitably, errors occur in the continuity of the surface contours of the printed model. Therefore, the layer thickness perpendicular to the powder layer direction is a critical factor. The presence of layer thickness causes contour deviations between the printed specimen and the model. This is especially true for specimens with curved surfaces, where the laser sintering process cannot achieve a smooth transition, resulting in stepped surfaces and reduced dimensional accuracy of the initial blank. Therefore, for parts with curved surfaces, increasing the layer thickness significantly amplifies the stepped effect, increasing the dimensional accuracy error between the actual sintered specimen and the design model. When preparing curved blanks, it is advisable to appropriately reduce the layer thickness.

[0134] Theoretically, reducing the layer thickness reduces the step effect and improves the precision of the resulting part. However, a smaller layer thickness is not always better. A smaller layer thickness, based on the principle that the powder particle size should be smaller than the single-layer thickness during sintering, requires the use of relatively small powder particles. However, excessively small powder particles are prone to agglomeration and static electricity, adhering to the powder spreading roller and causing difficulties or even failure in powder spreading. Furthermore, smaller layers require longer printing times, reducing molding efficiency. Therefore, the selection of layer thickness should follow the principle of matching the particle size of the printing powder and other process parameters.

[0135] Furthermore, the layer thickness affects energy absorption. Because laser sintering has a limited layer thickness, if the layer thickness exceeds the maximum laser distribution along the layer depth direction, the bottom of each layer may not be fully sintered, resulting in weak or even nonexistent bonding between layers. This leads to reduced strength in the Z-direction, and the specimen may even delaminate. However, excessively thin layer thickness will cause some sintered powder to be sintered repeatedly. This repeated sintering increases the temperature of the repeated layers, causing the epoxy resin to volatilize, which also reduces strength in the Z-direction.

[0136] S32. Set the printing direction of the 3D printing laser sintering system; select vertical printing;

[0137] S33. The composite powder is loaded into the 3D printing laser sintering system, and the SiC ceramic blank is prepared by the 3D printing laser sintering system.

[0138] S4. The SiC ceramic blank is densified by vacuum degreasing and PIP impregnation pyrolysis process.

[0139] The PIP process first involves filling a 3D-printed SiC ceramic preform with a polymer through infiltration impregnation. Then, the specimen filled with impregnation liquid is removed and placed in an electric thermostatic drying oven for curing. The cured preform is then placed in a vacuum high-temperature sintering furnace and subjected to high-temperature pyrolysis under a nitrogen protective atmosphere to generate the SiC matrix. Figure 18 This is a schematic diagram of the impregnation and pyrolysis of 3D-printed SiC ceramic material after degreasing. The vacuum high-temperature pyrolysis process parameters are shown in Table 2.

[0140] Table 2 High-Temperature Pyrolysis Process Parameters for SiC Ceramic Matrix Composites

[0141]

[0142] like Figure 19 The figure shows the relationship between the weight gain, porosity, and density of 3D-printed SiC ceramic matrix composites and the impregnation cycle. From... Figure 19 As shown in (a), the weight gain rate of the specimen was relatively large in the first three PIP cycles, and the weight gain curve gradually flattened in subsequent cycles. This is because, with the increase of the impregnation cycle, the porosity of the specimen continuously decreased, and the amount of impregnating solution in each impregnation also decreased, resulting in a gradual decrease in the mass of the SiC matrix formed. After 8 cycles of impregnation and pyrolysis, the weight gain rate of the specimen was less than 1%. Figure 19 (b) It can be seen that the porosity of the 3D-printed SiC ceramic matrix composite material continuously decreases with the increase of the impregnation pyrolysis cycle. After 8 cycles of impregnation pyrolysis, the porosity of the specimen is 24.32%, of which the open porosity is 5.05%. The density gradually increases with the increase of the impregnation cycle, and the density of the specimen reaches 2.45 g / cm³ after 8 cycles of impregnation pyrolysis. 3 The porosity was increased by 64.43% compared to the degreased state, indicating that the polymer impregnation pyrolysis method can effectively reduce the porosity and increase the density of 3D printed SiC ceramic matrix composites.

[0143] like Figures 2 to 15 As shown; the 3D printing laser sintering system used in step S3 includes a base 100; one end of the base 100 is provided with a rotating groove 101; the other end of the base 100 is provided with a powder feeding cylinder 201;

[0144] A circular platform 400 is provided above one end of the base 100, and a first support platform 200 is provided above the other end; a second powder cavity 401 is provided on the circular platform 400.

[0145] The first support platform 200 serves to install the powder feeding device 500 and facilitates the powder feeding device 500 to stop powdering.

[0146] The second powder chamber 401 set on the circular platform 400 mainly functions to recover excess powder and can also serve as a second powder supply chamber.

[0147] Guide rails 402 are provided on the circular platform 400 and the first support platform 200; a powder feeding device 500 is provided on the guide rails 402;

[0148] By mounting the powder feeding device on the guide rail 402, it is easier to control the movement trajectory of the powder feeding device and ensure the linear movement of the powder feeding device.

[0149] An arc-shaped gap exists between the first support platform 200 and the circular platform 400; a molding cavity rotating device 600 is provided inside the rotating groove 101; the molding cavity rotating device 600 has a rotating annular platform 603; multiple uniformly distributed molding cavities 602 are provided on the rotating annular platform 603; the molding cavity rotating device 600 realizes the rotation of multiple molding cavities; the rotating annular platform 603, the first support platform 200, and the circular platform 400 form a working platform;

[0150] A comprehensive processing system 700 is provided above the molding cavity rotating device 600; the comprehensive processing system includes a gas protection system, a dust extraction system, and a part removal system.

[0151] The gas protection system includes a housing 701 disposed above the working platform; the housing 701 forms a sealed space above the working platform; the gas protection system fills the sealed space with inert gas to achieve gas protection;

[0152] The dust extraction system removes dust from the workpiece inside the forming cavity 602; the part removal system provides a part removal station for the workpiece inside the forming cavity 602.

[0153] A laser forming scanning device 800 is provided above the rotating annular stage 603; the laser forming scanning device 800 is located above the guide rail 402; the laser forming scanning device 800 is used for laser scanning of the forming cavity 602.

[0154] During the operation, inert gas protection is first implemented throughout the entire process through a gas protection system; then, a forming cavity 602 on the forming cavity rotating device 600 is rotated between the guide rails 402, and the forming cavity 602 is positioned directly below the laser forming scanning device 800; then, powder is spread in the forming cavity 602 within the forming cavity rotating device 600 through the powder feeding device 500.

[0155] After the powder is applied, the powder feeding device 500 returns to its initial position, at which point it is positioned on the first support platform 200. Then, the laser forming scanning device 800 scans the forming cavity 602 to form the first layer of workpiece. This process is repeated to achieve workpiece scanning and printing. After the workpiece is printed, the forming cavity rotating device 600 rotates the next forming cavity between the guide rails 402, positioning the forming cavity 602 directly below the laser forming scanning device 800. The forming cavity with the formed workpiece is then rotated to the bottom of the dust collection system to perform dust collection. After the workpiece is dusted, the forming cavity rotating device 600 waits for the workpiece inside the forming cavity to be printed. After the workpiece is printed, the forming cavity rotating device 600 rotates, causing any undusted workpieces to be dusted and then rotated to the bottom of the part removal system for part removal.

[0156] Therefore, the 3D printing laser sintering system provided by this invention can replace the forming cavity through the forming cavity rotation device, and can also achieve workpiece dust suction and workpiece removal through the integrated processing system. By combining the forming cavity rotation device, the integrated processing system and the laser forming scanning device, printing, powder cleaning and part removal can be carried out simultaneously; thus improving production efficiency and reducing production costs.

[0157] The powder feeding device 500 includes a support frame 501; a powder storage cavity 502 is provided above the support frame 501; a powder spreading roller 503 is provided inside the support frame 501; and a powder adding nozzle 507 is provided above the powder storage cavity 502.

[0158] The support frame 501 has powder stripping blocks 504 on both sides of one end; a powder outlet 505 of the powder storage cavity 502 is provided between the two powder stripping blocks 504.

[0159] The other end of the support frame 501 is provided with a slider that matches the guide rail 402; the slider is provided with a sliding drive device 509; and the powder outlet 505 is provided with a powder quantity control device to control the amount of powder dispensed.

[0160] The support frame 501 can be made of stainless steel. Its main function is to provide support and move the powder storage chamber 502. The powder spreading roller 503 installed in the support frame 501 primarily spreads the powder. The powder storage chamber 502 primarily replenishes the powder when it is insufficient.

[0161] The sliding drive device 509 on the slider is mainly used to move the powder feeding device; the sliding drive device 509 can be a micro motor. The powder quantity control device inside the powder outlet 505 mainly controls the amount of powder added, and can be a rotary switch.

[0162] The powder feeding device 500 of the present invention can realize the traditional powder feeding chamber powder feeding and spreading through the powder spreading roller; it can also realize the powder box powder feeding and spreading through the powder storage chamber 502.

[0163] The molding cavity rotating device 600 includes a bottom rotating ring 601 and a top rotating ring platform 603.

[0164] The bottom rotating ring 601 can adopt a frame structure, which mainly serves to provide support. The top rotating ring platform 603 can be made of stainless steel to facilitate various workstations.

[0165] A support column 604 is provided between the bottom rotating ring 601 and the rotating ring platform 603.

[0166] The rotating annular platform 603 is provided with molding cavities 602 evenly distributed along the circumference; a first telescopic device 605 for adjusting the depth of the molding cavity 602 is provided below the molding cavity 602.

[0167] The inner ring of the rotating annular platform 603 matches the circular platform 400 and is rotated and sealed; the outer ring of the rotating annular platform 603 matches one end of the first support platform 200; the sealing fit can prevent inert gas leakage and reduce the amount of inert gas used in the whole process.

[0168] A sealing plate 607 is provided below the outer ring of the rotating annular platform 603 and is sealed to the lower end of the housing 701; the sealing plate 607 is in a rotating sealing fit with the rotating annular platform 603.

[0169] Specifically, the circular platform 400, the first support platform 200, and the rotating annular platform 603 form a working platform; the powder feeding device 500 can move along the guide rail on the working platform.

[0170] A rotation drive device 103 is provided on the base 100; an annular boss 102 is provided in the rotation groove 101; and a rotation sleeve 606 matching the annular boss 102 is provided on the inner ring of the bottom rotation ring 601.

[0171] The rotating sleeve 606 is fitted onto the annular boss 102 and rotates in cooperation with the annular boss 102.

[0172] A gear ring 6061 is provided at the upper end of the inner cavity of the rotating sleeve 606; the rotation drive device 103 is in transmission cooperation with the gear ring 6061.

[0173] Specifically, bearings can be installed between the rotating sleeve 606 and the annular boss 102 to achieve rotational engagement and support. The rotation drive device 6061 can be a motor to drive the gear ring, thereby realizing the rotation of the bottom rotating ring 601 and the rotating annular platform 603.

[0174] The integrated processing system includes a housing 701; the housing 701 includes a circular housing that matches the rotating ring stage 603 and a rectangular housing that matches the first support platform 200; the circular housing and the rectangular housing are connected; and the rectangular housing is sealed to the first support platform 200.

[0175] Both the rectangular and circular shells can be made of stainless steel and formed by welding.

[0176] A powder filling box 715 and an air suction device 716 are provided on the top of the rectangular shell; an air supply device 702 communicating with the inner cavity of the circular shell is provided on the top of the circular shell.

[0177] The gas supply device 702 and the gas intake device 716 together form a gas protection system, creating a circulating protective airflow.

[0178] Specifically, both the lower end of the air supply device 702 and the air intake device 716 are equipped with an air distribution plate 7161; the air distribution plate 7161 can disperse the airflow. By supplying air to the circular shell through the air supply device 702 and drawing air into the rectangular shell through the air intake device 716, the gas forms an airflow from the circular shell to the rectangular shell; then the gas absorbed by the air intake device is supplied to the air supply device to achieve airflow circulation.

[0179] The top of the circular shell is provided with a second telescopic device 708, a third telescopic device 706, a fourth telescopic device 707, a fifth telescopic device 709, and a guide cylinder 705; the fifth telescopic device 709 is located in the middle of the circular shell.

[0180] The laser forming scanning device 800 can move up and down through the fifth telescopic device 709;

[0181] The housing 701 is provided with a first dust suction cover connected to the second telescopic device 708; a second dust suction cover connected to the third telescopic device 706; and a part retrieval cover 717 connected to the fourth telescopic device 707.

[0182] The forming scanning mirror group 805, the first dust suction hood, the second dust suction hood, and the part removal hood 717 are respectively corresponding to a forming cavity 602 on the rotating annular stage 603;

[0183] Both the first and second dust hoods include a hood body 901; the top of the hood body 901 is provided with an annular air supply ring 902; and an air supply pipe 904 is provided on the annular air supply ring 902.

[0184] The cover 901 is provided with an exhaust plate 907 that communicates with the annular air supply ring 902 inside; the exhaust plate 907 is provided with evenly distributed exhaust nozzles; the lower end of the cover 901 is provided with an annular air intake pipe 905; the annular air intake pipe 905 is provided with an air intake nozzle 906; the lower end of the inner cavity of the cover 901 is provided with an air intake hole 908 that communicates with the annular air intake pipe 905.

[0185] The top of the circular housing is provided with a first air supply device 704 connected to the air supply pipe 904 of the first dust hood and a second air supply device 703 connected to the air supply pipe 904 of the second dust hood.

[0186] A vacuum cleaner 300 corresponding to the first and second vacuum hoods is provided at the lower end of one side of the circular housing; the vacuum cleaner 300 has a suction pipe 302; the inner wall of the circular housing is provided with a nozzle groove that matches the air intake 906; a suction nozzle 303 communicating with the suction pipe 302 is provided at the bottom of the nozzle groove; the suction nozzle 303 matches the air intake 906;

[0187] The second telescopic device 708, the third telescopic device 706, the first dust suction hood, the second dust suction hood, and the vacuum cleaner 300 form a dust suction system to achieve dust suction of the workpiece in the forming cavity 602.

[0188] In the specific working process, when the molding cavity rotates to the area below the first and second dust suction hoods, the first and second dust suction hoods move downwards under the action of the second telescopic device 708 and the third telescopic device 706, respectively, so that the bottom of the dust suction hoods is tightly attached to the rotating annular platform 603. Specifically, a rubber pad layer can be set at the lower end of the first and second dust suction hoods to achieve compression sealing. Then, the first air supply device 704 and the air supply pipe 904 of the second dust suction hood are activated, and the vacuum cleaner 300 is started. The first air supply device 704 supplies air through the exhaust plate 907 to blow away the dust on the workpiece; the vacuum cleaner 300 sucks in the air, so that the suction hole 908 absorbs the dust inside the hood, thereby achieving dust suction.

[0189] A part-retrieving port 712 is provided on one side of the circular shell; sliding grooves 711 are provided on both sides of the part-retrieving port 712; a slider 713 that seals the part-retrieving port 712 is installed in the sliding grooves 711;

[0190] The part-retrieving cover 717 has an opening 7171 on one side; a sealing cavity 7172 is provided on the side wall on both sides of the opening 7171; a sliding groove matching the part-retrieving cover 717 is provided inside the circular shell, and the opening 7171 matches the part-retrieving port 712.

[0191] The fourth telescopic device, the part-removing cover 717, and the part-removing port 712 and slider 713 provided on the circular shell form a part-removing system, providing a part-removing station for the workpiece in the forming cavity 602.

[0192] Specifically, during the operation, the fourth telescopic device moves the part-retrieving cover 717 downwards to seal the molding cavity below it; at this time, the part-retrieving cover 717 and the molding cavity are separated from the entire circular housing cavity; then the slider 713 is opened, and the part is retrieved through the part-retrieving port 712. After the part is retrieved, the fourth telescopic device moves the part-retrieving cover 717 upwards to reset it.

[0193] The powder filling box 715 is provided with a powder dispensing nozzle 718 at its lower end; the powder dispensing nozzle 718 is provided with a transverse sliding groove 719 communicating with the powder dispensing nozzle 718 at its lower end; the transverse sliding groove 719 matches the powder filling nozzle 507; a flow switch 720 is provided inside the powder dispensing nozzle 718.

[0194] When the powder supply in the powder feeding device 500 is insufficient, the powder feeding nozzle 507 slides below the powder leakage nozzle 718 and the flow switch 720 is turned on; thereby allowing the powder in the powder feeding box 715 to enter the powder feeding device 500 to replenish the powder; therefore, the device described in this invention facilitates automatic powder replenishment.

[0195] The laser forming scanning device 800 includes a support rod 801; a telescopic shaft 803 is provided above one end of the support rod 801; and a guide column 802 is provided above the other end.

[0196] A laser 804 is provided at the lower end of one end of the support rod 801; a forming scanning mirror group 805 is provided at the other end.

[0197] The telescopic shaft 803 is driven to extend and retract via the fifth telescopic device 709; the guide column 802 is slidably engaged with the guide cylinder 705.

[0198] A laser rangefinder 710 is mounted on the top of the circular housing; the probe of the laser rangefinder 710 is located directly above the support rod 801.

[0199] During operation, laser 804 emits laser light, and the laser power can be adjusted in real time. The forming scanning mirror assembly 805 then changes the laser path to achieve laser scanning and printing on the forming cavity. The laser scanning distance can be controlled by the extension and retraction of the fifth telescopic device. The laser range sensor 710 monitors and adjusts the distance in real time.

[0200] In a feasible embodiment, to prevent residual dust on the rotating annular stage 603 from affecting the molding cavity, a powder scraper 403 is further provided on the guide rail 402 above the gap between the circular platform 400 and the first support platform 200. The powder scraper 403 can remove residual dust on the rotating annular stage 603, ensuring the cleanliness of the working platform during powder application and preventing dust from mixing into the powder and entering the molding cavity.

[0201] In a feasible embodiment, to facilitate automated control, the first telescopic device 605, the second telescopic device 708, the third telescopic device 706, the fourth telescopic device 707, and the fifth telescopic device 709 are hydraulic cylinders or electric push rods.

[0202] In one feasible embodiment, in order to avoid damage to the components of the equipment by dust in the environment and to facilitate observation of the working status of the equipment, a transparent annular cover 610 is provided between the bottom rotating ring 601 and the top rotating annular platform 603 of the molding cavity rotating device 600.

Claims

1. A 3D printing process for silicon carbide ceramic matrix composite materials, characterized in that, Includes the following steps: S1. Select SiC powder and binder; The SiC powder is selected as a printing powder with a particle size of 10-150μm; The adhesive is NH4H2PO4, aluminum powder, or epoxy resin; S2. Preparation of composite powder; Composite powder is prepared by mixing binder and SiC powder using mechanical mixing or kneading methods. S3. Using a 3D printing laser sintering system to print SiC ceramic blanks; The 3D printing laser sintering system includes a base (100); a rotating groove (101) is provided at one end of the base (100); and a powder feeding cylinder (201) is provided at the other end of the base (100). A circular platform (400) is provided above one end of the base (100), and a first support platform (200) is provided above the other end; a second powder cavity (401) is provided on the circular platform (400); Guide rails (402) are provided on the circular platform (400) and the first support platform (200); a powder feeding device (500) is provided on the guide rails (402); An arc-shaped gap exists between the first support platform (200) and the circular platform (400); a molding cavity rotating device (600) is provided in the rotating groove (101); the molding cavity rotating device (600) has a rotating annular platform (603); a plurality of uniformly distributed molding cavities (602) are provided on the rotating annular platform (603); the molding cavity rotating device (600) realizes the rotation of the plurality of molding cavities; the rotating annular platform (603), the first support platform (200) and the circular platform (400) form a working platform; An integrated processing system (700) is provided above the molding cavity rotating device (600); the integrated processing system includes a gas protection system, a dust extraction system, and a part removal system; The gas protection system includes a housing (701) disposed above the working platform; the housing (701) forms a sealed space above the working platform; the gas protection system fills the sealed space with inert gas to achieve gas protection; The dust collection system removes dust from the workpiece inside the forming cavity (602); the part removal system provides a part removal station for the workpiece inside the forming cavity (602). A laser forming scanning device (800) is provided above the rotating ring stage (603); the laser forming scanning device (800) has a forming scanning mirror group (805); The laser forming scanning device (800) is located above the guide rail (402); the laser forming scanning device (800) is used for laser scanning of the forming cavity (602); S4. The SiC ceramic preform is densified by vacuum degreasing and PIP impregnation pyrolysis process. The integrated processing system includes a housing (701); the housing (701) includes a circular housing that matches the rotating ring stage (603) and a rectangular housing that matches the first support platform (200); the circular housing and the rectangular housing are in communication; and the rectangular housing is sealed to the first support platform (200); A powder filling box (715) and an air suction device (716) are provided on the top of the rectangular shell; an air supply device (702) communicating with the inner cavity of the circular shell is provided on the top of the circular shell; The gas supply device (702) and the gas intake device (716) together form a gas protection system, creating a circulating protective airflow; The top of the circular shell is provided with a second telescopic device (708), a third telescopic device (706), a fourth telescopic device (707), a fifth telescopic device (709), and a guide cylinder (705); the fifth telescopic device (709) is located in the middle of the circular shell; The laser forming scanning device (800) moves up and down via the fifth telescopic device (709); The housing (701) is provided with a first dust suction hood connected to the second telescopic device (708); a second dust suction hood connected to the third telescopic device (706); and a part retrieval hood (717) connected to the fourth telescopic device (707); The forming scanning mirror assembly (805), the first dust suction hood, the second dust suction hood, and the part removal hood (717) are respectively associated with a forming cavity (602) on the rotating annular stage (603); Both the first and second dust hoods include a hood body (901); the top of the hood body (901) is provided with an annular air supply ring (902); and an air supply pipe (904) is provided on the annular air supply ring (902). The cover (901) is provided with an exhaust plate (907) that communicates with the annular air supply ring (902) inside; the exhaust plate (907) is provided with evenly distributed exhaust nozzles; the lower end of the cover (901) is provided with an annular air intake pipe (905); the annular air intake pipe (905) is provided with an air intake nozzle (906); the lower end of the inner cavity of the cover (901) is provided with an air intake hole (908) that communicates with the annular air intake pipe (905); The top of the circular housing is provided with a first air supply device (704) connected to the air supply pipe (904) of the first dust hood and a second air supply device (703) connected to the air supply pipe (904) of the second dust hood. A vacuum cleaner (300) corresponding to the first and second vacuum hoods is provided at the lower end of one side of the circular housing; the vacuum cleaner (300) has a suction pipe (302); the inner wall of the circular housing is provided with a nozzle groove that matches the suction nozzle (906); a suction nozzle (303) communicating with the suction pipe (302) is provided at the bottom of the nozzle groove; the suction nozzle (303) matches the suction nozzle (906); The second telescopic device (708), the third telescopic device (706), the first dust hood, the second dust hood, and the vacuum cleaner (300) form a dust collection system to achieve dust collection of the workpiece in the forming cavity (602).

2. The 3D printing silicon carbide ceramic matrix composite material preparation process as described in claim 1, characterized in that: Step S3, which uses a 3D printing laser sintering system to print SiC ceramic blanks, also includes the following steps: S31. Optimize the laser parameters, composite powder preheating temperature, and printing layer thickness. The laser parameter is the laser energy density; the laser energy density is optimized according to the following formula; In the formula: q is the laser energy density; K is the proportionality coefficient; P is the laser power; V is the laser scanning speed; and D is the scanning spacing. The laser power in the formula is such that the powder in the scanning area is bonded together, while the powder in the non-scanning area around the scanning area is not bonded together; the laser power, laser scanning speed and scanning spacing are optimized through orthogonal experiments. The powder preheating temperature is determined by the glass transition temperature of the resin; the powder preheating temperature is lower than the glass transition temperature; glass transition temperature - powder preheating temperature = ΔT; where ΔT is determined according to process requirements. S32. Set the printing direction of the 3D printing laser sintering system; select vertical printing; S33. The composite powder is loaded into the 3D printing laser sintering system, and the SiC ceramic blank is prepared by the 3D printing laser sintering system.

3. The 3D printing silicon carbide ceramic matrix composite material preparation process as described in claim 2, characterized in that: The molding cavity rotating device (600) includes a bottom rotating ring (601) and a top rotating ring platform (603); A supporting column (604) is provided between the bottom rotating ring (601) and the rotating ring platform (603); The rotating annular platform (603) is provided with molding cavities (602) evenly distributed along the circumference; a first telescopic device (605) for adjusting the depth of the molding cavity (602) is provided below the molding cavity (602); The inner ring of the rotating annular platform (603) matches the circular platform (400) and is in a rotating sealed fit; The outer ring of the rotating annular platform (603) matches one end of the first support platform (200); A sealing plate (607) is provided below the outer ring of the rotating annular platform (603) and is sealed to the lower end of the housing (701); the sealing plate (607) is in a rotating sealing fit with the rotating annular platform (603); A rotation drive device (103) is provided on the base (100); an annular boss (102) is provided in the rotation groove (101); and a rotating sleeve (606) matching the annular boss (102) is provided in the inner ring of the bottom rotating ring (601). The rotating sleeve (606) is fitted onto the annular boss (102) and rotates in conjunction with the annular boss (102); A gear ring (6061) is provided at the upper end of the inner cavity of the rotating sleeve (606); the rotating drive device (103) is in transmission cooperation with the gear ring (6061).

4. The 3D printing silicon carbide ceramic matrix composite material preparation process as described in claim 3, characterized in that: A part-removing port (712) is provided on one side of the circular shell; sliding grooves (711) are provided on both sides of the part-removing port (712); a slider (713) for sealing the part-removing port (712) is installed in the sliding groove (711); The part-retrieving cover (717) has an opening (7171) on one side; a sealing cavity (7172) is provided on the side wall on both sides of the opening (7171); a sliding groove matching the part-retrieving cover (717) is provided inside the circular shell, and the opening (7171) matches the part-retrieving port (712); The fourth telescopic device, the part-removing cover (717), and the part-removing port (712) and slider (713) provided on the circular shell form a part-removing system, providing a part-removing station for the workpiece in the forming cavity (602).

5. The preparation process of 3D printed silicon carbide ceramic matrix composite material as described in claim 1, characterized in that: The powder feeding device (500) includes a support frame (501); A powder storage chamber (502) is provided above the support frame (501); a powder spreading roller (503) is provided inside the support frame (501); and a powder adding nozzle (507) is provided above the powder storage chamber (502). The support frame (501) has powder stripping blocks (504) on both sides of one end; a powder outlet (505) of the powder storage cavity (502) is provided between the two powder stripping blocks (504); The other end of the support frame (501) is provided with a slider that matches the guide rail (402); the slider is provided with a sliding drive device (509); and the powder outlet (505) is provided with a powder quantity control device for controlling the amount of powder dispensed.

6. The 3D printing silicon carbide ceramic matrix composite material preparation process as described in claim 5, characterized in that: The powder filling box (715) is provided with a powder dispensing nozzle (718) at its lower end; the powder dispensing nozzle (718) is provided with a transverse sliding groove (719) communicating with the powder dispensing nozzle (718) at its lower end; the transverse sliding groove (719) matches the powder filling nozzle (507); a flow switch (720) is provided inside the powder dispensing nozzle (718).

7. The 3D printing silicon carbide ceramic matrix composite material preparation process as described in claim 6, characterized in that: The laser forming scanning device (800) includes a support rod (801); a telescopic shaft (803) is provided above one end of the support rod (801); and a guide column (802) is provided above the other end. A laser (804) is provided at the lower end of one end of the support rod (801); a forming scanning mirror assembly (805) is provided at the other end; The telescopic shaft (803) is driven to extend and retract via the fifth telescopic device (709); the guide column (802) is slidably engaged with the guide cylinder (705); A laser rangefinder (710) is provided on the top of the circular housing; the probe of the laser rangefinder (710) is located directly above the support rod (801).

8. The preparation process of 3D printed silicon carbide ceramic matrix composite material as described in claim 7, characterized in that: A powder scraper (403) is provided on the guide rail (402) above the gap between the circular platform (400) and the first support platform (200).

9. The 3D printing process for silicon carbide ceramic matrix composite materials as described in claim 4, characterized in that: The first telescopic device (605), the second telescopic device (708), the third telescopic device (706), the fourth telescopic device (707), and the fifth telescopic device (709) are hydraulic cylinders or electric push rods.

10. The 3D printing process for silicon carbide ceramic matrix composite materials as described in claim 4, characterized in that: A transparent annular cover (610) is provided between the bottom rotating ring (601) and the top rotating annular platform (603) of the molding cavity rotating device (600).

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