A multi-interface protection C f Additive manufacturing methods for SiC and its complex structural components

Abstract

This invention discloses a multi-interface protection C f This invention relates to an additive manufacturing method for silicon carbide (SiC) and its complex structural components, belonging to the field of silicon carbide ceramic manufacturing technology. The method includes: mixing carbon fibers and silicon carbide powder in a graded manner to obtain a mixed powder; depositing the mixed powder through powder layer-by-layer printing to obtain a carbon fiber / silicon carbide preform; and obtaining a porous intermediate after degreasing treatment. The porous intermediate is then subjected to sequential chemical vapor infiltration to deposit a pyrolytic carbon interface layer, chemical vapor infiltration to deposit a ceramic interface layer, and slurry impregnation and pyrolysis to fill a carbonaceous sacrificial layer, thereby forming a multi-layered composite interface protection structure on the carbon fiber surface. The preform, after undergoing multi-interface protection treatment, is then subjected to reactive melting and post-processing to obtain high-toughness, high fiber retention rate SiC preforms. f / SiC ceramic complex structural components. This invention realizes the development of high-content carbon fiber / silicon carbide composite powder, improves the packing density of the composite powder and the uniformity of carbon fiber dispersion; and significantly improves the toughness of silicon carbide materials.

Description

Technical Field

[0001] This invention belongs to the field of silicon carbide ceramic manufacturing technology, specifically relating to a multi-interface protected C f Additive manufacturing method for SiC and its complex structural components. Background Technology

[0002] Silicon carbide (SiC) is an indispensable key material in modern industry, especially in high-temperature, high-pressure, high-frequency, and corrosive environments. In terms of mechanical properties, silicon carbide ceramics exhibit extremely high flexural strength, hardness, and wear resistance. Its hardness is second only to diamond and cubic boron nitride, and its flexural strength remains at a high level of 500-600 MPa even at 1400℃. In terms of thermal and chemical properties, its thermal conductivity is second only to beryllium oxide ceramics, enabling rapid heat dissipation and making it suitable for heat sinks and packaging materials in high-power electronic devices. Simultaneously, its low coefficient of thermal expansion gives the material good thermal shock resistance, allowing it to withstand drastic temperature changes without cracking. Furthermore, silicon carbide has good chemical inertness to most acids and alkalis. In high-temperature oxidizing environments, a dense silica protective film forms on its surface, preventing further oxygen diffusion and internal oxidation. Therefore, silicon carbide is widely used as abrasives and nozzles, gas turbine blades, high-temperature bearings, and wear-resistant components in heat exchangers.

[0003] However, the performance advantages determined by the strong covalent bonds and highly directional bonding of silicon carbide also bring a fundamental drawback—low room-temperature fracture toughness. When subjected to applied stress, silicon carbide ceramics lack the ability to undergo plastic deformation through dislocation slip like metals. Once a crack initiates, it propagates rapidly, leading to catastrophic failure. This intrinsic brittleness severely limits its application in structural components with extremely high reliability requirements. Therefore, how to effectively improve its toughness while maintaining its excellent performance has long been a research focus in the field of materials science.

[0004] To address the brittle nature of silicon carbide ceramics, researchers have drawn on strengthening concepts from metallic and composite materials, developing various toughening methods and processes. The core idea is to introduce a second phase or specific structure within the material to prevent fracture by consuming crack propagation energy, altering crack propagation paths, or shielding stress at the crack tip. Major toughening methods include fiber / whisker toughening, particle dispersion toughening, and nano / structure toughening.

[0005] Additive manufacturing technology enables the one-piece fabrication of complex structural components. In the field of additive manufacturing (3D printing), introducing a second phase into silicon carbide and maximizing its toughening effect is a key technical challenge. The inhomogeneity of multi-component composite systems naturally affects the 3D printing process and imposes numerous limitations on subsequent sintering. The mismatch in geometry between carbon fiber and silicon carbide powder, poor uniformity of the composite powder system, complex property control processes, difficulty in controlling the densification process of the preform before sintering, and the susceptibility of carbon fiber to damage during reaction sintering all contribute to the challenges in additive manufacturing of silicon carbide. f SiC materials often have low carbon fiber content, resulting in no significant improvement in toughness. Furthermore, the density and strength of the material are reduced due to the incorporation of carbon fibers. Therefore, high-toughness SiC... f Breakthroughs are urgently needed in additive manufacturing methods for SiC. Summary of the Invention

[0006] The technical problem to be solved: To overcome the shortcomings of existing technologies, this invention provides a multi-interface protection C f An additive manufacturing method for SiC and its complex structural components involves first performing vapor phase deposition of a carbon interface on the preform, followed by liquid phase impregnation of silicon carbide, and combining this with specific process design to achieve high-toughness SiC. f The printing and sintering of SiC solves the current C f The additive manufacturing process of SiC faces significant challenges in toughening.

[0007] The technical solution of this invention is: a multi-interface protection C f The additive manufacturing method for SiC and its complex structural components, with the following specific steps: S1. Carbon fibers of different mesh sizes are mixed with silicon carbide powders of different particle sizes in a graded manner, and the physical properties of the mixed powder are adjusted to make it suitable for powder bed preparation. S2. The mixed powder is formed by powder bed additive manufacturing process to obtain a ceramic blank rich in carbon fiber, and the ceramic blank is degreased to obtain a porous intermediate. S3. The porous intermediate is subjected to chemical vapor infiltration to deposit a pyrolytic carbon interface layer, chemical vapor infiltration to deposit a ceramic interface layer, and slurry impregnation and pyrolysis to fill a carbonaceous sacrificial layer, thereby forming a multi-layer composite interface protection structure on the carbon fiber surface, and obtaining an intermediate after multi-interface protection treatment; the multi-layer composite interface protection structure is used in the reaction melting and infiltration process as a sacrificial reaction layer, a molten silicon isolation layer, and a fiber-matrix weak bonding layer in sequence. S4. The intermediate, after multi-interface protection treatment, undergoes reactive melt infiltration treatment, followed by post-processing to obtain C with high toughness and high fiber retention rate. f / SiC ceramic complex structural components.

[0008] A further technical solution of the present invention is: in S1, the length of the carbon fiber is distributed in the range of 100 mesh to 1000 mesh, and the median particle size of the silicon carbide powder is distributed in the range of 1 micrometer to 300 micrometers; The graded mixture is a two-graded compound system, that is, at least two kinds of carbon fibers with different mesh sizes are mixed evenly with at least two kinds of silicon carbide powder with different particle sizes, and the volume fraction of carbon fibers in the mixed powder is between 10% and 90%. A further technical solution of the present invention is: in step S1, the adjusted physical properties of the mixed powder are: loose density 0.9–1.7 g / cm³. 3 Tap density 1.2–2.0 g / cm³ 3 The angle of repose is 30° to 45°.

[0009] A further technical solution of the present invention is as follows: In step S2, the powder bed additive manufacturing process is a binder spray molding process or a selective laser sintering process; the degreasing treatment is carried out under an inert protective atmosphere or vacuum, the heating rate is controlled below 2℃ / min, and a segmented heat preservation method is adopted. The heating rate below 800℃ is controlled below 2℃ / min, and the temperature is kept at 300℃, 550℃, and 800℃ for 0.5 to 5 hours respectively. After that, the heating rate is unlimited, and the temperature is raised to any temperature within the range of 800℃ to 1800℃. After holding for 0.5 to 5 hours, the temperature is cooled. A further technical solution of the present invention is: in S3, the chemical vapor infiltration process for depositing the pyrolytic carbon interface uses methane, propylene or ethylene as the carbon source, the deposition temperature is 1000-1500℃, and the deposition is performed once or multiple times. A further technical solution of the present invention is: in S3, the ceramic deposited by the chemical vapor infiltration process for depositing the ceramic interface is selected from one or more of silicon carbide, boron carbide, boron nitride or silicon nitride, the deposition temperature is 700-1500℃, and the deposition is performed once or more.

[0010] A further technical solution of the present invention is: in S3, the slurry impregnation pyrolysis process includes, in sequence: impregnation pyrolysis using a nano-carbon impregnation liquid containing nano-carbon powder, and impregnation pyrolysis using a resin impregnation liquid; the number of impregnation pyrolysis operations is independently one or more times, and one or more roughing processes are performed during this process.

[0011] A further technical solution of the present invention is: in step S3, the nano-carbon in the nano-carbon impregnation liquid is selected from one or more of diamond, graphite carbon or amorphous carbon, and its particle size distribution is 0.1 micrometer to 1 micrometer; the resin in the resin impregnation liquid is selected from one or more of epoxy resin, phenolic resin, polyimide or furfural resin.

[0012] A further technical solution of the present invention is: in S4, the reactive melting infiltration treatment is gas-phase silicon infiltration, liquid-phase silicon infiltration, or gas-liquid phase synergistic silicon infiltration, and the silicon infiltration temperature is 1400-1700℃; the post-processing includes at least one roughing process performed after the slurry impregnation and pyrolysis step and before the reactive melting infiltration treatment, and a finishing process performed after the reactive melting infiltration treatment. The silicon raw material is one or more of high-purity silicon powder, high-purity silicon blocks, or silicon blocks made by bonding high-purity silicon powder.

[0013] A C prepared according to the preparation method f / SiC ceramic complex structural parts, the C f The retention rate of carbon fibers inside complex SiC ceramic structures after reactive infiltration is greater than 80%, and the fracture toughness of the material is ≥5.5 MPa·m. 1 / 2 .

[0014] Beneficial effects The beneficial effects of this invention are as follows: The method of this invention is based on powder bed additive manufacturing process, and utilizes a multi-interface protection strategy to perform gas / liquid phase treatment on the carbon fiber / silicon carbide composite preform obtained after 3D printing of graded mixed powder, thereby achieving high-toughness C f The printing and sintering of SiC significantly improves the toughness of the material. Specific effects are analyzed below: (1) This invention realizes the printing of short carbon fiber / silicon carbide dual-graded powder mixture: short carbon fibers of different mesh sizes work together, with longer carbon fibers interspersed in the porous preform, improving the preform strength and material toughness; shorter carbon fibers alleviate the problem of uneven carbon fiber dispersion, improve the uniformity of the mixture, and make it suitable for powder-layout printing. The silicon carbide gradation system further increases the bulk density of the powder and further increases the density of the preform. This dual-graded system allows for a higher proportion of carbon fiber component in printable carbon fiber / silicon carbide composite powder and provides a prerequisite for the molding of complex mechanical structural parts.

[0015] (2) This invention employs a multi-interface protection strategy to achieve a high "survival rate" of carbon fibers during the melting and infiltration process: a pyrolytic carbon interface layer and a ceramic interface layer are deposited by vapor phase deposition, and then nano-carbon / resin-pyrolyzed carbon interface is impregnated by liquid phase deposition to form a multi-layered interface system. During the preparation of this interface, the density of the green body also continuously increases, resulting in higher density and strength after sintering. The nano-carbon and resin-pyrolyzed carbon infiltrated by impregnation and pyrolysis serve as a reaction / sacrificial layer, the vapor-deposited ceramic interface layer serves as an isolation layer from gas / liquid silicon, and the vapor-deposited pyrolytic carbon interface serves as a weak bonding interface between the fiber and the matrix. During the reaction sintering process, liquid silicon first reacts fully with the outermost nano-carbon and resin-decomposed carbon to generate silicon carbide. Then, gaseous / liquid silicon further erodes into the fibers, which are isolated by the ceramic interface layer, allowing most of the carbon fibers to be retained. During the material fracture process, a large number of short fibers near the fracture point help deflect the crack and consume a large amount of fracture energy. If the interface bonding is too strong, the fibers will only contribute strength and little toughness. The weak interface of the innermost pyrolytic carbon causes the crack to preferentially propagate along this interface, which is equivalent to consuming more energy in front of the crack, further improving the toughening effect of the carbon fibers.

[0016] In this invention, through the design of a two-gradation system for a composite powder of high-toughness carbon fiber mixed with silicon carbide and a multi-interface protection strategy, carbon fiber reinforced silicon carbide is prepared with the following characteristics: the fiber volume fraction can be greater than 50%; the fiber survival rate before and after reaction sintering is greater than 80%; and the overall density of the material can reach 2.75–2.95 g / cm³. 3 The material's flexural strength is 240–300 MPa; its maximum fracture toughness is ≥5.5 MPa·m. 1 / 2 The material's high fracture toughness originates from its two-stage carbon fiber and silicon carbide powder system, allowing for additive manufacturing of C... f The higher carbon fiber content incorporated during the / SiC process, along with the multi-layered interface protection design of the carbon fiber surface sacrificial layer, insulating layer, and weak bonding layer, ensures that more carbon fibers are retained during reaction sintering, providing sufficient fracture energy dissipation points for material fracture. The interface preparation process is synchronized with the preform densification treatment, and the material density is essentially guaranteed through multiple processes, thus possessing sufficient density and strength. Fewer harmful defects also create a prerequisite for high fracture toughness. Based on this method, C... f Additive manufacturing of complex SiC structural components. Attached Figure Description

[0017] Figure 1 The high-toughness C in the multi-interface protection embodiment of the present invention is f / SiC process flow diagram; Figure 2 This is the preform formed by BJ printing of high volume fraction carbon fiber / silicon carbide composite powder in the embodiments of the present invention; Figure 3These are the carbon fiber / silicon carbide mechanical test specimen strips after reaction sintering in the embodiments of the present invention; Figure 4 These are carbon fiber / silicon carbide fracture toughness test strips obtained by fine processing after reaction sintering in the embodiments of the present invention. Figure 5 This is a transmission electron microscope (TEM) image of the pyrolytic carbon interface on the carbon fiber surface deposited by chemical vapor deposition in an embodiment of the present invention. Figure 6 This is a scanning electron microscope image of the silicon carbide interface chemically vapor-deposited on the surface of carbon fibers coated with pyrolytic carbon in an embodiment of the present invention. Figure 7 This is a diagram showing the internal fiber morphology of the material after reaction sintering in an embodiment of the present invention; Figure 8 This is an image of the fiber pull-out section of the material cross-section in an embodiment of the present invention; Figure 9 This is a calculated image of the fiber area content of the material cross-section in an embodiment of the present invention; Figure 10 This is the force-displacement diagram of the fracture toughness of the material in Example 1; Figure 11 C prepared using the method of this invention f / A photo of the 3D printed blank of the SiC material fuel nozzle support plate; Figure 12 C prepared using the method of this invention f / A photo of the SiC material fuel nozzle support plate; Figure 13 C prepared using the method of this invention f / Photo of the 3D printed blank of the vibration test fixture bracket for the silicon carbide reflector made of SiC material; Figure 14 C prepared using the method of this invention f / A photo of the actual fixture bracket for vibration testing of silicon carbide reflectors made of SiC material. Detailed Implementation

[0018] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0019] Based on the current C f The additive manufacturing process for SiC faces the significant challenge of toughening, and existing technologies have made the following improvements: CN120574055A solves the forming and basic toughening problems of complex components (vortex generators) through "spray granulation" and "two-step PIP", but its fiber protection mechanism and the final toughness improvement are limited.

[0020] CN111018537A simplifies the process and achieves effective fiber protection through "SiC powder gradation" and "secondary carbonization," but its protective layer is simple and fails to overcome the bottleneck of fiber content and toughness.

[0021] To address the aforementioned problems, this invention organically integrates three interface layers with different functions: CVI pyrolytic carbon (weak interface), CVI ceramic (physical barrier), and slurry-impregnated carbon (sacrificial layer). This integration, combined with bi-graded high-fiber-content powder and a multi-step densification process, systematically solves the problems associated with additive manufacturing of CVI. f The core challenge in SiC composite materials is "how to achieve ultra-high fiber retention rate with high fiber content and ultimately obtain extremely high fracture toughness". The specific technical solution is as follows: A multi-interface protection C f The additive manufacturing method for SiC and its complex structural components, with the following specific steps: S1. Carbon fibers of different mesh sizes are mixed with silicon carbide powders of different particle sizes in a graded manner, and the physical properties of the mixed powder are adjusted to make it suitable for powder bed preparation. S2. The mixed powder is formed by powder bed additive manufacturing process to obtain a ceramic blank rich in carbon fiber, and the ceramic blank is degreased to obtain a porous intermediate. S3. The porous intermediate is subjected to chemical vapor infiltration to deposit a pyrolytic carbon interface layer, chemical vapor infiltration to deposit a ceramic interface layer, and slurry impregnation and pyrolysis to fill a carbonaceous sacrificial layer, thereby forming a multi-layer composite interface protection structure on the carbon fiber surface, and obtaining an intermediate after multi-interface protection treatment; the multi-layer composite interface protection structure is used in the reaction melting and infiltration process as a sacrificial reaction layer, a molten silicon isolation layer, and a fiber-matrix weak bonding layer in sequence. S4. The intermediate, after multi-interface protection treatment, undergoes reactive melt infiltration treatment, followed by post-processing to obtain C with high toughness and high fiber retention rate. f / SiC ceramic complex structural components.

[0022] The above technical solution will be further explained below with reference to examples and accompanying drawings: Example 1 Reference Figure 1 As shown, a C-type multi-interface protection f The additive manufacturing method for complex SiC structural components, with the following process flow: (1) Mix 400 mesh and 200 mesh carbon fibers in a ratio of 9:1 with silicon carbide powder (50 mesh, 70 mesh and 200 mesh in a ratio of 3:6.5:0.5). The volume fraction of carbon fibers in the mixed powder is 30%. Adjust the physical properties of the mixed powder to: loose density 0.9~1.9 g / cm³ 3Tap density: 1.2–2.2 g / cm³ 3 An angle of repose of 30° to 45° is used to ensure that the mixed powder is evenly spread on the printing platform under the action of the powder spreading roller / scraper. (2) The mixed powder was formed by binder jet molding (BJ) using furan resin binder. The preform was slowly degreased at a heating rate of 0.5℃ / min, and held at 450℃, 650℃ and 900℃ for one hour each. After reaching 900℃, it was cooled down with the furnace to obtain a porous intermediate, such as... Figure 2 As shown; (3) The porous intermediate obtained after degreasing was placed in a graphite box with a porous structure, and pyrolytic carbon was deposited by chemical vapor infiltration (CVI). Each batch of deposition lasted 3 days and was repeated 2 times to obtain intermediate 1. (4) Intermediate 1 was placed in a porous graphite box and a silicon carbide interface protective layer was deposited by chemical vapor infiltration (CVI). Each batch of deposition lasted 3 days and was repeated 2 times to obtain intermediate 2. (5) Nanographite was uniformly dispersed in a phenolic resin / ethanol solution (resin to ethanol ratio of 1:2), with a nanographite mass fraction of 5%. Intermediate 2 was impregnated in the above slurry at a pressure of 2 MPa for 0.5 h, followed by pyrolysis using a degreasing temperature program. This impregnation and pyrolysis was repeated once. Subsequently, a phenolic resin / ethanol solution (resin to ethanol ratio of 1:1) was used for impregnation at a pressure of 2 MPa for 0.5 h, followed by pyrolysis using a degreasing temperature program. This impregnation and pyrolysis was repeated three times to obtain intermediate 3. After each impregnation and pyrolysis, the material underwent necessary rough processing.

[0023] (6) The intermediate 3 is placed in a boron nitride crucible and subjected to gas-liquid phase synergistic reaction sintering (RMI) to obtain the sintered product, such as... Figure 3 An unprocessed three-point bending mechanical specimen strip, after which the material is processed to obtain the required C-shape. f / SiC ceramics, such as Figure 4 Fracture toughness test specimen strips.

[0024] Example 2 The difference from Example 1 is that in step (4), a boron nitride interface protective layer is deposited. Each batch of deposits takes 3 days and is repeated 2 times to obtain intermediate 2. All other steps are the same.

[0025] Example 3 The difference from Example 1 lies in step (2), where 15% by mass of phenolic resin is incorporated into the mixed powder, and selective laser sintering (SLS) is used for printing. The preform is slowly degreased at a heating rate of 0.5℃ / min, and held at 450℃, 650℃, and 900℃ for one hour each. After reaching 900℃, it is cooled down with the furnace to obtain the intermediate. All other steps are the same.

[0026] Example 4 The difference from Example 1 is in step (1), where 400-mesh carbon fiber is selected and mixed with silicon carbide powder (50-mesh, 70-mesh and 200-mesh in a ratio of 3:6.5:0.5), with a fiber volume fraction of 30%. The physical properties of the powder are adjusted so that the powder can be evenly spread on the printing platform under the action of the powder spreading roller / scraper. All other steps are the same.

[0027] Example 5 Based on the process scheme of Example 1, a fuel nozzle support plate structure with hollow channels was successfully manufactured, such as... Figure 11 , 12 As shown.

[0028] Example 6 Based on the process scheme of Example 1, a vibration dynamics test fixture suitable for silicon carbide mirrors was successfully manufactured, such as... Figure 13 , 14 As shown.

[0029] Comparative Example 1 The difference from Example 1 is that step (1) is omitted, and 400-mesh carbon fiber is used and mixed with 70-mesh silicon carbide powder, with a fiber volume fraction of 30%. All other steps are the same.

[0030] Comparative Example 2 The difference from Example 1 is that step (3) is omitted. All other steps are the same.

[0031] Comparative Example 3 The difference from Example 1 is that step (4) is omitted. All other steps are the same.

[0032] Comparative Example 4 The difference from Example 1 is that step (5) is omitted. All other steps are the same.

[0033] To more clearly demonstrate the beneficial effects of the method of the present invention, the material test results of the above embodiments and comparative examples are listed in Table 1: Table 1. Performance test results of carbon fiber / silicon carbide composite materials prepared in the examples and comparative examples.

[0034] As can be seen from the table above, Examples 1 and 2 demonstrate the effectiveness of the combination of the pyrolytic carbon interface and the ceramic interface in protecting the carbon fibers from erosion during silicon infiltration. Examples 1 and 3 demonstrate that the carbon fiber / silicon carbide dual-grade composite powder is suitable for BJ and SLS processes in powder bed powdering, and can achieve 3D printing of high fiber volume fraction carbon fiber / silicon carbide composite powder. Examples 1-3 demonstrate that the process described in this invention can significantly improve the fracture toughness of 3D printed carbon fiber reinforced silicon carbide. Comparative Examples 1-3 respectively show the preparation of the pyrolytic carbon interface, the preparation of the ceramic interface, and the slurry impregnation process, and the fiber retention rate is low, indicating that none of them can effectively isolate the erosion of the carbon fibers by gaseous and molten silicon. The preparation of the interface protective layer is also a process of gradually densifying the preform and gradually introducing the carbon source, so the density and flexural strength of Comparative Examples 1-3 are low.

[0035] Figure 5 and Figure 6 This study demonstrates the feasibility of a multi-interface fabrication process by showcasing a pyrolytic carbon interface deposited by chemical vapor deposition on a carbon fiber surface and a silicon carbide interface deposited by chemical vapor deposition on a carbon fiber surface coated with pyrolytic carbon. After reaction sintering, the internal fibers of the material largely maintain their original morphology and are less susceptible to erosion by liquid silicon. Figure 7 In the fracture surface of the material, obvious traces of fiber pull-out are visible. Figure 8 The fiber area content of multiple material profiles was measured and the average value was taken. Figure 9 The carbon fiber content inside the material after reaction sintering can be determined by the volume fraction of carbon fibers in the powder, thus yielding the fiber retention rate. The carbon fiber retention rate after reaction sintering using the process described in this invention can reach over 80%. This high fiber content results in a higher fracture toughness of 5.0 MPa·m. 1 / 2 The above, up to a maximum of 5.57 MPa·m 1 / 2 ( Figure 10 ).

[0036] The two-stage arrangement of fiber and silicon carbide yields 3D printing powder with good dispersibility and flowability, which is beneficial for achieving 3D printing of silicon carbide powder with higher volume fraction fiber content. This method allows the carbon fiber volume fraction in the 3D printing raw material to reach 90%. The multi-interface protection mechanism of pyrolytic carbon, ceramic, and elemental / pyrolytic carbon ensures that most of the carbon fiber is retained during the silicon infiltration process, with a fiber retention rate of up to 80% or more. Simultaneously, it exhibits high flexural strength and density, making 3D printing of silicon carbide powder more efficient. f The toughness of SiC materials has exceeded 5.0 MPa·m. 1 / 2 Based on this method, additive manufacturing of the fuel nozzle support plate structure in Example 4 was achieved. Figure 11 and Figure 12These are the printed fuel nozzle support plate blank and the sintered finished product, respectively; achieving the C-shaped size greater than 500 mm in Example 5. f / Additive manufacturing of SiC scaffolds ( Figure 13 and Figure 14 These are the printed support blank and the sintered finished product, respectively, and have been successfully used as a vibration dynamics testing fixture for silicon carbide mirrors. This method can be extended to the manufacture of other similar silicon carbide structural components.

[0037] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A multi-interface protection C f An additive manufacturing method for SiC and its complex structural components, characterized in that... The specific steps are as follows: S1. Carbon fibers of different mesh sizes are mixed with silicon carbide powders of different particle sizes in a graded manner, and the physical properties of the mixed powder are adjusted to make it suitable for powder bed preparation. S2. The mixed powder is formed by powder bed additive manufacturing process to obtain a ceramic blank rich in carbon fiber, and the ceramic blank is degreased to obtain a porous intermediate. S3. The porous intermediate is subjected to chemical vapor infiltration to deposit a pyrolytic carbon interface layer, chemical vapor infiltration to deposit a ceramic interface layer, and slurry impregnation and pyrolysis to fill a carbonaceous sacrificial layer, thereby forming a multi-layer composite interface protection structure on the carbon fiber surface, and obtaining an intermediate after multi-interface protection treatment. The multilayer composite interface protection structure is used sequentially as a sacrificial reaction layer, a molten silicon isolation layer, and a fiber-matrix weak bonding layer during the reactive melting and infiltration process; S4. The intermediate, after multi-interface protection treatment, undergoes reactive melt infiltration treatment, followed by post-processing to obtain C with high toughness and high fiber retention rate. f / SiC ceramic complex structural components.

2. The C-type multi-interface protection according to claim 1 f An additive manufacturing method for SiC and its complex structural components, characterized by: In S1, the carbon fiber length is distributed in the range of 100 mesh to 1000 mesh, and the median particle size of the silicon carbide powder is distributed in the range of 1 micrometer to 300 micrometers. The graded mixture is a two-graded compound system, that is, at least two kinds of carbon fibers with different mesh sizes are mixed evenly with at least two kinds of silicon carbide powder with different particle sizes, and the volume fraction of carbon fibers in the mixed powder is between 10% and 90%.

3. A multi-interface protection C according to claim 1 f An additive manufacturing method for SiC and its complex structural components, characterized by: In step S1, the adjusted physical properties of the mixed powder are: loose density 0.9–1.9 g / cm³. 3 Tap density 1.2–2.2 g / cm³ 3 The angle of repose is 30° to 45°.

4. A multi-interface protection C according to claim 1 f An additive manufacturing method for SiC and its complex structural components, characterized by: In S2, the powder bed additive manufacturing process is a binder spray molding process or a selective laser sintering process; the degreasing treatment is carried out under an inert protective atmosphere or vacuum, and a segmented heat preservation method is adopted. The heating rate below 800℃ is controlled below 2℃ / min, and the temperature is kept at 300℃, 550℃, and 800℃ for 0.5 to 5 hours respectively. After that, the heating rate is unlimited, and the temperature is raised to any temperature within the range of 800℃ to 1800℃. After holding at the temperature for 0.5 to 5 hours, the temperature is cooled.

5. A multi-interface protection C according to claim 1 f An additive manufacturing method for SiC and its complex structural components, characterized by: In step S3, the chemical vapor infiltration process for depositing the pyrolytic carbon interface uses methane, propylene, or ethylene as the carbon source, the deposition temperature is 1000–1500°C, and the deposition is performed once or multiple times.

6. A multi-interface protection C according to claim 1 f An additive manufacturing method for SiC and its complex structural components, characterized by: In step S3, the ceramic deposited by the chemical vapor infiltration process for depositing the ceramic interface is selected from one or more of silicon carbide, boron carbide, boron nitride, or silicon nitride, the deposition temperature is 700-1500℃, and the deposition is performed once or multiple times.

7. A multi-interface protection C according to claim 1 f An additive manufacturing method for SiC and its complex structural components, characterized by: In S3, the slurry impregnation pyrolysis process includes, in sequence: impregnation pyrolysis using a nano-carbon impregnation solution containing nano-carbon powder, and impregnation pyrolysis using a resin impregnation solution; the number of impregnation pyrolysis operations is independently one or more times, and one or more roughing processes are performed during this process.

8. A multi-interface protection C according to claim 1 f An additive manufacturing method for SiC and its complex structural components, characterized by: In step S3, the nano-carbon in the nano-carbon impregnation solution is selected from one or more of diamond, graphite carbon, or amorphous carbon, and its particle size distribution is 0.1 micrometer to 1 micrometer; the resin in the resin impregnation solution is selected from one or more of epoxy resin, phenolic resin, polyimide, or furfural resin.

9. A multi-interface protection C according to claim 1 f An additive manufacturing method for SiC and its complex structural components, characterized by: In S4, the reactive melting infiltration treatment is gas-phase silicon infiltration, liquid-phase silicon infiltration, or gas-liquid phase synergistic silicon infiltration, and the silicon infiltration temperature is 1400-1700℃; the post-processing includes at least one roughing process performed after the slurry impregnation and pyrolysis step and before the reactive melting infiltration treatment, and a finishing process performed after the reactive melting infiltration treatment. The silicon raw material is one or more of high-purity silicon powder, high-purity silicon blocks, or silicon blocks made by bonding high-purity silicon powder.

10. A C prepared by the preparation method according to any one of claims 1-9 f / SiC ceramic complex structural components, characterized by: The C f The retention rate of carbon fibers inside complex SiC ceramic structures after reactive infiltration is greater than 80%, and the fracture toughness of the material is ≥5.5 MPa·m. 1 / 2 .

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