Infiltration sintering process of ceramic skeleton reinforced silicon nitride composite ceramic

Abstract

The invention discloses an infiltration sintering process of a ceramic skeleton reinforced silicon nitride composite ceramic, and belongs to the technical field of ceramic processing, communicated pores are reserved by pre-sintering a skeleton, a guarantee is provided for full filling of silicon nitride-based slurry, silicon powder added in the slurry is subjected to an in-situ chemical reaction with the surface of the skeleton in an integrated sintering process, and the surface of the skeleton is subjected to an in-situ chemical reaction; a stable transition phase is formed, so that the interface bonding is enhanced; the porosity, the pore size, the boundary dimension and the internal structure can be accurately regulated and controlled through 3D printing of the prefabricated framework, vacuum-pressure infiltration ensures that the slurry can uniformly and fully fill the pores of the framework, the problem of insufficient local infiltration is avoided, framework pre-sintering and matrix sintering are combined into one procedure through integrated sintering, the secondary processing step is reduced, and the production efficiency is improved. The defect generation probability caused by secondary sintering is reduced, the technological process is simplified, the controllability is high, the method is suitable for industrial batch production, the production cost is reduced, and the production efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of ceramic processing technology, and particularly relates to the infiltration and sintering process of ceramic skeleton-reinforced silicon nitride multiphase ceramics. Background Technology

[0002] Silicon nitride ceramics, as an advanced structural ceramic, occupy an important position in modern industry due to their excellent properties such as high strength, high hardness, high temperature resistance, corrosion resistance, and wear resistance. In the aerospace field, it can be used to manufacture key components such as engine combustion chambers and turbine blades, capable of withstanding the erosion and corrosion of high-temperature combustion gases. In mechanical engineering, it can be used to manufacture high-precision bearings and seals, significantly improving the operating efficiency and service life of mechanical equipment. In the automotive industry, it is expected to be used in engine pistons, cylinder liners, and other components to achieve weight reduction, energy saving, and performance improvement. However, pure silicon nitride ceramics have obvious performance shortcomings. They have low fracture toughness and high brittleness, making them prone to fracture under impact or complex stress. At the same time, their high-temperature creep resistance is insufficient, and they are prone to plastic deformation under long-term high-temperature service environments, leading to a decrease in the dimensional stability of components. These defects seriously limit their further application in extreme environments and high-end equipment.

[0003] To improve the mechanical properties of silicon nitride ceramics, existing technologies often employ particle reinforcement (such as adding SiC, A, etc.). Multiphase synthesis schemes using particles or fibers (such as carbon fibers and SiC fibers) are being explored. Among these, fiber / skeleton reinforcement has become a research hotspot due to its ability to significantly improve toughness through "bridging" and "pull-out" effects. However, existing fabrication processes have the following drawbacks: Traditional sintering processes (such as hot pressing and gas pressure sintering) require mixing the reinforcing phase (fiber / skeleton) with silicon nitride matrix powder before molding and sintering. This can easily lead to an overly strong or weak bond between the reinforcing phase and the matrix, and the fibers are easily damaged during the mixing process. The impregnation process often adopts a step-by-step approach of "sintering the skeleton first and then impregnating the matrix slurry". The interface bonding between the skeleton and the matrix is ​​poor, and a second high-temperature sintering is required after impregnation, which can easily lead to thermal expansion mismatch between the skeleton and the matrix and generate microcracks. Existing ceramic framework materials (such as SiC framework) have insufficient chemical compatibility with silicon nitride matrix, and are prone to interfacial reactions at high temperatures (such as the formation of low melting point phases), which reduces the high-temperature performance of the material.

[0004] Therefore, there is an urgent need to develop a new process that can optimize the enhanced phase-matrix interface, has strong process controllability, and can mass-produce high-performance silicon nitride multiphase ceramics. Summary of the Invention

[0005] The purpose of this invention is to address the problem that existing ceramic framework materials (such as SiC framework) have insufficient chemical compatibility with silicon nitride matrix, and are prone to interfacial reactions at high temperatures (such as the formation of low-melting-point phases), which reduce the high-temperature performance of the material. Therefore, this invention proposes an infiltration and sintering process for ceramic framework-reinforced silicon nitride multiphase ceramics.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The infiltration and sintering process for ceramic-reinforced silicon nitride multiphase ceramics includes the following steps: S1: Pre-fabricated ceramic skeleton: Selected with a thermal expansion coefficient ≤1×1 compared to silicon nitride. Ceramic materials at / ℃ are used to prepare green bodies through 3D printing, and then pre-sintered at 1200-1400℃ to obtain a ceramic skeleton with a porosity of 30-50%. S2: Preparation of silicon nitride-based slurry: Using silicon nitride powder as the matrix, sintering aids, 0.1-0.5% silicon powder and dispersant are added and mixed to form a slurry with a solid content of 60-70%; S3: Impregnation treatment: After vacuum treatment of the ceramic skeleton, it is impregnated with silicon nitride-based slurry under a pressure of 0.5-2MPa and then dried; S4: Integrated sintering: Sintering at 1600-1800℃ for 2-4 hours in a nitrogen atmosphere, achieving interfacial bonding through in-situ reaction between silicon powder and the skeleton, to obtain multiphase ceramics; S5: Performance testing: Perform various performance tests on the prepared multiphase ceramics.

[0007] As a further description of the above technical solution: The ceramic material in step S1 is either silane or aluminum nitride.

[0008] As a further description of the above technical solution: The 3D printing in step S1 is photopolymerization molding, with a skeleton pore size of 50-200μm.

[0009] As a further description of the above technical solution: The sintering aid in step S2 is: -A Composite additives, with a mass fraction of 5-15%.

[0010] As a further description of the above technical solution: The sintering atmosphere in step S4 is nitrogen, with a pressure of 0.1-0.5 MPa, and a heating rate of 5 °C / min during the high-temperature stage.

[0011] As a further description of the above technical solution: The S1: ceramic skeleton prefabrication includes: Selection of framework material: Choose ceramic materials with excellent chemical compatibility with the silicon nitride matrix, such as silane or aluminum nitride, whose coefficient of thermal expansion differs from that of silicon nitride by ≤1×1. / ℃ (25-1000℃); Skeleton forming: Skeleton powder with a particle size of 1-5μm is mixed with polyvinyl alcohol with a mass fraction of 5-10%, and a green body with a three-dimensional interconnected pore structure is prepared by 3D printing, with a porosity of 30-50% and a pore size of 50-200μm; Skeleton pre-sintering: The green body is pre-sintered in a nitrogen atmosphere with a heating rate of 5-10℃ / min, a sintering temperature of 1200-1400℃, and a holding time of 2-4h to obtain a ceramic skeleton with a density of 60-70%, retaining interconnected pores to facilitate subsequent infiltration. The preparation of S2: silicon nitride-based slurry includes: Slurry formulation: Using silicon nitride powder with a particle size of 0.5-2μm and a mass fraction of 70-80% as the matrix, and adding 5-15% by mass of... -A Composite additives are used as sintering aids, polyethylene glycol (0.5-2% by mass) is used as a dispersant, and deionized water is mixed by ball milling for 2-4 hours to form a mixture with a solid content of 60-70% and a viscosity of 500-1000 mPa. A uniform slurry; Adding 0.1-0.5% of silicon powder with a particle size of 1-3μm to the slurry allows for in-situ reaction with the skeleton surface during sintering, thereby strengthening the interfacial bonding. The S3: impregnation treatment includes: The pre-sintered ceramic skeleton was placed in a vacuum impregnation device, and the vacuum was drawn to ≤10Pa and maintained for 30min. Inject silicon nitride-based slurry into the device, apply nitrogen pressure of 0.5-2 MPa, and maintain the pressure for 1-2 hours to allow the slurry to fully fill the interconnected pores of the skeleton. Remove the impregnated green body and dry it at 60-80℃ for 12-24 hours to remove free moisture; S4: Integrated sintering includes: The impregnated green body was placed in a graphite sintering furnace and sintered in a nitrogen atmosphere at a pressure of 0.1-0.5 MPa. Low temperature stage (room temperature - 800℃): heating rate 5℃ / min, to remove organic components from the green body; Intermediate temperature stage (800-1600℃): Heating rate 10℃ / min, promotes melting of sintering aids and formation of liquid phase; High temperature stage (1600-1800℃): heating rate 5℃ / min, holding for 2-4h. At this time, the silicon powder reacts in situ with the surface of the skeleton, realizing the interfacial bonding between the skeleton and the matrix. S5: Performance testing: The prepared multiphase ceramics are tested for bending strength, fracture toughness, and creep resistance at 1200℃.

[0012] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: In this invention, the pre-sintered skeleton retains interconnected pores, ensuring sufficient filling of the silicon nitride-based slurry. The silicon powder added to the slurry undergoes an in-situ chemical reaction with the skeleton surface during the integrated sintering process, forming a stable transition phase. This creates a "chemical bond" interface between the skeleton and the silicon nitride matrix, increasing the interface bonding strength by 30-50% (≥80MPa) and enhancing the interface bonding. Thanks to the excellent interfacial bonding between the framework and the matrix, as well as the "bridging" and "pull-out" reinforcement effects of the framework, the flexural strength of the multiphase ceramic is ≥800MPa, and the fracture toughness is ≥7MPa. The m¹ / ² is increased by 20% and 40% respectively compared to pure silicon nitride ceramics, improving the mechanical properties of multiphase ceramics and making them less prone to fracture when subjected to impact or complex stress. Because the thermal expansion of the skeleton and the matrix is ​​matched (difference ≤ 1×1) / ℃), effectively reducing the degree of thermal expansion mismatch between the skeleton and the matrix, significantly reducing the thermal stress generated during sintering and cooling and high-temperature service, avoiding the generation of microcracks, reducing the creep rate by 50% at 1200℃, and without interface reaction deterioration, resulting in good high-temperature stability of the prepared multiphase ceramic. 3D printing prefabricated skeletons allow for precise control of porosity, pore size, external dimensions, and internal structure, meeting the customized needs of different products. Vacuum-pressure impregnation ensures that the slurry can uniformly and fully fill the skeleton pores, avoiding the problem of insufficient impregnation in certain areas. Integrated sintering combines the pre-sintering of the skeleton with the sintering of the matrix into a single process, reducing secondary processing steps and lowering the probability of defects caused by secondary sintering. The process is simplified, highly controllable, and suitable for industrial mass production, which helps to reduce production costs and improve production efficiency. Detailed Implementation

[0013] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0014] In its specific implementation, the present invention provides a technical solution: The infiltration and sintering process for ceramic-reinforced silicon nitride multiphase ceramics includes the following steps: S1: Pre-fabricated ceramic skeleton: Selected with a thermal expansion coefficient ≤1×1 compared to silicon nitride. Ceramic materials at / ℃ are used to prepare green bodies through 3D printing, and then pre-sintered at 1200-1400℃ to obtain a ceramic skeleton with a porosity of 30-50%. S2: Preparation of silicon nitride-based slurry: Using silicon nitride powder as the matrix, sintering aids, 0.1-0.5% silicon powder and dispersant are added and mixed to form a slurry with a solid content of 60-70%; S3: Impregnation treatment: After vacuum treatment of the ceramic skeleton, it is impregnated with silicon nitride-based slurry under a pressure of 0.5-2MPa and then dried; S4: Integrated sintering: Sintering at 1600-1800℃ for 2-4 hours in a nitrogen atmosphere, achieving interfacial bonding through in-situ reaction between silicon powder and the skeleton, to obtain multiphase ceramics; S5: Performance testing: Perform various performance tests on the prepared multiphase ceramics.

[0015] The ceramic material in step S1 is either silane or aluminum nitride.

[0016] The 3D printing in step S1 is photopolymerization molding, with a skeleton pore size of 50-200μm.

[0017] The sintering aid in step S2 is -A Composite additives, with a mass fraction of 5-15%.

[0018] The sintering atmosphere in step S4 is nitrogen, with a pressure of 0.1-0.5 MPa, and a heating rate of 5 °C / min in the high-temperature stage.

[0019] S1: Prefabricated ceramic skeleton includes: Selection of framework material: Choose ceramic materials with excellent chemical compatibility with the silicon nitride matrix, such as silane or aluminum nitride, whose coefficient of thermal expansion differs from that of silicon nitride by ≤1×1. / ℃ (25-1000℃); Skeleton forming: Skeleton powder with a particle size of 1-5μm is mixed with polyvinyl alcohol with a mass fraction of 5-10%, and a green body with a three-dimensional interconnected pore structure is prepared by photopolymerization 3D printing, with a porosity of 30-50% and a pore size of 50-200μm. Skeleton pre-sintering: The green body is pre-sintered in a nitrogen atmosphere with a heating rate of 5-10℃ / min, a sintering temperature of 1200-1400℃, and a holding time of 2-4h to obtain a ceramic skeleton with a density of 60-70%, retaining interconnected pores to facilitate subsequent infiltration. S2: Preparation of silicon nitride-based slurry includes: Slurry formulation: Using silicon nitride powder with a particle size of 0.5-2μm and a mass fraction of 70-80% as the matrix, and adding 5-15% by mass of... -A Composite additives are used as sintering aids, polyethylene glycol (0.5-2% by mass) is used as a dispersant, and deionized water is mixed by ball milling for 2-4 hours to form a mixture with a solid content of 60-70% and a viscosity of 500-1000 mPa. A uniform slurry; Adding 0.1-0.5% of silicon powder with a particle size of 1-3μm to the slurry allows for in-situ reaction with the skeleton surface during sintering, thereby strengthening the interfacial bonding. S3: Impregnation treatment includes: The pre-sintered ceramic skeleton was placed in a vacuum impregnation device, and the vacuum was drawn to ≤10Pa and maintained for 30min. Inject silicon nitride-based slurry into the device, apply nitrogen pressure of 0.5-2 MPa, and maintain the pressure for 1-2 hours to allow the slurry to fully fill the interconnected pores of the skeleton. Remove the impregnated green body and dry it at 60-80℃ for 12-24 hours to remove free moisture; S4: Integrated sintering includes: The impregnated green body was placed in a graphite sintering furnace and sintered in a nitrogen atmosphere at a pressure of 0.1-0.5 MPa. Low temperature stage (room temperature - 800℃): heating rate 5℃ / min, to remove organic components from the green body; Intermediate temperature stage (800-1600℃): Heating rate 10℃ / min, promotes melting of sintering aids and formation of liquid phase; High temperature stage (1600-1800℃): heating rate 5℃ / min, holding for 2-4h. At this time, the silicon powder reacts in situ with the surface of the skeleton, realizing the interfacial bonding between the skeleton and the matrix. S5: Performance testing: The prepared multiphase ceramics are tested for bending strength, fracture toughness, and creep resistance at 1200℃.

[0020] Example 1: The infiltration and sintering process for ceramic-reinforced silicon nitride multiphase ceramics includes the following steps: S1: Pre-fabricated ceramic skeleton: Selected with a thermal expansion coefficient ≤1×1 compared to silicon nitride. Ceramic materials at / ℃ are used to prepare green bodies through 3D printing, and then pre-sintered at 1200-1400℃ to obtain a ceramic skeleton with a porosity of 30-50%. S2: Preparation of silicon nitride-based slurry: Using silicon nitride powder as the matrix, sintering aids, 0.1-0.5% silicon powder and dispersant are added and mixed to form a slurry with a solid content of 60-70%; S3: Impregnation treatment: After vacuum treatment of the ceramic skeleton, it is impregnated with silicon nitride-based slurry under a pressure of 0.5-2MPa and then dried; S4: Integrated sintering: Sintering at 1600-1800℃ for 2-4 hours in a nitrogen atmosphere, achieving interfacial bonding through in-situ reaction between silicon powder and the skeleton, to obtain multiphase ceramics; S5: Performance testing: Perform various performance tests on the prepared multiphase ceramics.

[0021] The ceramic material used in step S1 is silane.

[0022] The 3D printing in step S1 is photopolymerization molding, with a skeleton pore size of 50-200μm.

[0023] The sintering aid in step S2 is -A Composite additives, with a mass fraction of 5-15%.

[0024] The sintering atmosphere in step S4 is nitrogen, with a pressure of 0.1-0.5 MPa, and a heating rate of 5 °C / min in the high-temperature stage.

[0025] S1: Prefabricated ceramic skeleton includes: Selection of framework material: Choose a ceramic material with excellent chemical compatibility with the silicon nitride matrix, such as silane, whose coefficient of thermal expansion differs from that of silicon nitride by ≤1×1. / ℃ (25-1000℃); Skeleton forming: Skeleton powder with a particle size of 1-5μm is mixed with 10% polyvinyl alcohol by mass, and a green body with a three-dimensional interconnected pore structure is prepared by photopolymerization 3D printing, with a porosity of 40% and a pore size of 100μm. Skeleton pre-sintering: The green body is pre-sintered in a nitrogen atmosphere at a heating rate of 5-10℃ / min, a sintering temperature of 1300℃, and a holding time of 3h to obtain a ceramic skeleton with a density of 65%, retaining interconnected pores to facilitate subsequent infiltration. S2: Preparation of silicon nitride-based slurry includes: Slurry formulation: Using silicon nitride powder with a particle size of 0.5-2μm and a mass fraction of 75% as the matrix, and adding 10% by mass of... -A Composite additives are used as sintering aids, among which -A A mixture of polyethylene glycol (1% by mass, 1% by mass) and deionized water was ball-milled for 3 hours to form a solution with a solid content of 65% and a viscosity of 800 mPa. A uniform slurry; Adding 0.3% silicon powder with a particle size of 1-3μm to the slurry allows it to react in situ with the skeleton surface during sintering, thereby strengthening the interfacial bonding. S3: Impregnation treatment includes: The pre-sintered ceramic skeleton was placed in a vacuum impregnation device, and the vacuum was drawn to ≤10Pa and maintained for 30min. Inject silicon nitride-based slurry into the device, apply nitrogen pressure of 1 MPa, and maintain the pressure for 1.5 hours to allow the slurry to fully fill the interconnected pores of the skeleton. Remove the impregnated green body and dry it at 80℃ for 20 hours to remove free moisture; S4: Integrated sintering includes: The impregnated green body was placed in a graphite sintering furnace and sintered in a nitrogen atmosphere at a pressure of 0.3 MPa. Low temperature stage (room temperature - 800℃): heating rate 5℃ / min, to remove organic components from the green body; Intermediate temperature stage (800-1600℃): Heating rate 10℃ / min, promotes melting of sintering aids and formation of liquid phase; High temperature stage (1600-1800℃): heating rate 5℃ / min, heating to 1700℃ and holding for 3h. At this time, the silicon powder and the surface of the skeleton react in situ, realizing the interfacial bonding between the skeleton and the matrix. S5: Performance Tests: Bending strength 850MPa, fracture toughness 7.5MPa m 1 / 2 Creep resistance at 1200℃ is 2.0×10⁻⁶. -8 / h -1 .

[0026] Example 2: The infiltration and sintering process for ceramic-reinforced silicon nitride multiphase ceramics includes the following steps: S1: Pre-fabricated ceramic skeleton: Selected with a thermal expansion coefficient ≤1×1 compared to silicon nitride. Ceramic materials at / ℃ are used to prepare green bodies through 3D printing, and then pre-sintered at 1200-1400℃ to obtain a ceramic skeleton with a porosity of 30-50%. S2: Preparation of silicon nitride-based slurry: Using silicon nitride powder as the matrix, sintering aids, 0.1-0.5% silicon powder and dispersant are added and mixed to form a slurry with a solid content of 60-70%; S3: Impregnation treatment: After vacuum treatment of the ceramic skeleton, it is impregnated with silicon nitride-based slurry under a pressure of 0.5-2MPa and then dried; S4: Integrated sintering: Sintering at 1600-1800℃ for 2-4 hours in a nitrogen atmosphere, achieving interfacial bonding through in-situ reaction between silicon powder and the skeleton, to obtain multiphase ceramics; S5: Performance testing: Perform various performance tests on the prepared multiphase ceramics.

[0027] The ceramic material used in step S1 is aluminum nitride.

[0028] The 3D printing in step S1 is photopolymerization molding, with a skeleton pore size of 50-200μm.

[0029] The sintering aid in step S2 is -A Composite additives, with a mass fraction of 5-15%.

[0030] The sintering atmosphere in step S4 is nitrogen, with a pressure of 0.1-0.5 MPa, and a heating rate of 5 °C / min in the high-temperature stage.

[0031] S1: Prefabricated ceramic skeleton includes: Selection of framework material: Choose a ceramic material with excellent chemical compatibility with the silicon nitride matrix, such as aluminum nitride, whose coefficient of thermal expansion differs from that of silicon nitride by ≤1×1. / ℃ (25-1000℃); Skeleton forming: Skeleton powder with a particle size of 1-5μm is mixed with 8% polyvinyl alcohol by mass, and a green body with a three-dimensional interconnected pore structure is prepared by photopolymerization 3D printing, with a porosity of 35% and a pore size of 80μm. Skeleton pre-sintering: The green body is pre-sintered in a nitrogen atmosphere at a heating rate of 5-10℃ / min, a sintering temperature of 1400℃, and a holding time of 2h to obtain a ceramic skeleton with a density of 68%, retaining interconnected pores to facilitate subsequent infiltration. S2: Preparation of silicon nitride-based slurry includes: Slurry formulation: Using silicon nitride powder with a particle size of 0.5-2μm and a mass fraction of 80% as the matrix, and adding 8% by mass of... -A Composite additives are used as sintering aids, among which -A A mixture of polyethylene glycol (0.8% by mass) and deionized water at a mass ratio of 2:1 was ball-milled for 4 hours to form a mixture with a solid content of 70% and a viscosity of 900 mPa. A uniform slurry; Adding 0.3% silicon powder with a particle size of 1-3μm to the slurry allows it to react in situ with the skeleton surface during sintering, thereby strengthening the interfacial bonding. S3: Impregnation treatment includes: The pre-sintered ceramic skeleton was placed in a vacuum impregnation device, and the vacuum was drawn to ≤10Pa and maintained for 30min. Inject silicon nitride-based slurry into the device, apply nitrogen pressure of 1.5 MPa, and maintain the pressure for 2 hours to allow the slurry to fully fill the interconnected pores of the skeleton. Remove the impregnated blank and dry it at 70℃ for 24 hours to remove free moisture; S4: Integrated sintering includes: The impregnated green body was placed in a graphite sintering furnace and sintered in a nitrogen atmosphere at a pressure of 0.5 MPa. Low temperature stage (room temperature - 800℃): heating rate 5℃ / min, to remove organic components from the green body; Intermediate temperature stage (800-1600℃): Heating rate 10℃ / min, promotes melting of sintering aids and formation of liquid phase; High temperature stage (1600-1800℃): heating rate 5℃ / min, heating to 1750℃ and holding for 2h. At this time, silicon powder and skeleton surface react in situ to achieve interfacial bonding between skeleton and matrix. S5: Performance Tests: Bending strength 820MPa, fracture toughness 7.2MPa m 1 / 2 Creep resistance at 1200℃ is 2.3×10⁻⁶ -8 / h -1 .

[0032] As can be seen from the comparison of the above embodiments, the multiphase ceramics prepared using silane or AlN framework materials and combined with an integrated sintering process exhibit higher interfacial bonding strength, flexural strength, fracture toughness, and high-temperature creep resistance. The flexural strength is ≥800MPa and the fracture toughness is ≥7MPa. m 1 / 2 The creep resistance at 1200℃ is ≤2.5×10. -8 / h -1 .

Claims

1. A process for the infiltration sintering of ceramic framework reinforced silicon nitride composite ceramics, characterized in that, The method comprises the following steps: S1: Pre-fabricated ceramic skeleton: Selected with a thermal expansion coefficient ≤1×1 compared to silicon nitride. Ceramic materials at / ℃ are used to prepare green bodies through 3D printing, and then pre-sintered at 1200-1400℃ to obtain a ceramic skeleton with a porosity of 30-50%. S2: silicon nitride-based slurry preparation: taking silicon nitride powder as the base, adding sintering aids, 0.1-0.5% silicon powder and dispersants, and mixing to form a slurry with a solid content of 60-70%; S3: impregnation treatment: after vacuum treatment of the ceramic skeleton, the silicon nitride-based slurry is impregnated under a pressure of 0.5-2 MPa, and then dried; S4: integrated sintering: sintering at 1600-1800 ℃ for 2-4 h in a nitrogen atmosphere, realizing interface bonding through in-situ reaction of the silicon powder and the skeleton, and obtaining the composite ceramic; S5: performance test: testing the prepared composite ceramic for various performances.

2. The infiltration sintering process of ceramic skeleton reinforced silicon nitride composite ceramics according to claim 1, characterized in that, The ceramic material in the S1 step is one of silicon nitride or aluminum nitride.

3. The infiltration sintering process of ceramic skeleton reinforced silicon nitride composite ceramics according to claim 2, characterized in that, The 3D printing in the S1 step is light solidification molding, and the skeleton aperture is 50-200 μm.

4. The infiltration sintering process of ceramic skeleton reinforced silicon nitride composite ceramics according to claim 3, characterized in that, The sintering aid in the S2 step is -A Composite aid, 5-15% by mass.

5. The infiltration sintering process of ceramic skeleton reinforced silicon nitride composite ceramics according to claim 4, characterized in that, The sintering atmosphere in the S4 step is nitrogen, the pressure is 0.1-0.5 MPa, and the high-temperature stage has a heating rate of 5 ℃ / min.

6. The impregnation sintering process of the ceramic skeleton reinforced silicon nitride composite ceramic according to claim 5, wherein The S1: ceramic skeleton preparation comprises: Skeleton material selection: select ceramic materials such as sialon or aluminum nitride which have excellent chemical compatibility with silicon nitride matrix, and the difference of thermal expansion coefficient with silicon nitride is ≤1×10-6 / ℃ (25-1000℃) / ℃ (25-1000℃) Skeleton molding: mixing skeleton powder with a particle size of 1-5 μm and polyvinyl alcohol with a mass fraction of 5-10%, and preparing a green body with a three-dimensional interconnected pore structure through 3D printing, the porosity being 30-50%, and the aperture being 50-200 μm; Skeleton pre-sintering: pre-sintering the green body in a nitrogen atmosphere, the heating rate being 5-10 ℃ / min, the sintering temperature being 1200-1400 ℃, and the holding time being 2-4 h, so as to obtain a ceramic skeleton with a density of 60-70% and retained interconnected pores, facilitating subsequent impregnation; The S2: silicon nitride-based slurry preparation comprises: The slurry formula: taking the silicon nitride powder with the particle size of 0.5-2 μm and the mass fraction of 70-80% as the matrix, adding the composite additive with the mass fraction of 5-15% -A The composite additive as the sintering additive, the polyethylene glycol with the mass fraction of 0.5-2% as the dispersant and the deionized water are ball-mixed for 2-4 h to form the uniform slurry with the solid content of 60-70% and the viscosity of 500-1000 mPa s. Adding 0.1-0.5% silicon powder with a particle size of 1-3 μm in the slurry, which is used for in-situ reaction with the skeleton surface during sintering to strengthen the interface bonding; The S3: impregnation treatment comprises: Placing the pre-sintered ceramic skeleton in a vacuum impregnation device, and vacuumizing to ≤10 Pa and holding for 30 min; Injecting the silicon nitride-based slurry into the device, applying a nitrogen pressure of 0.5-2 MPa, and holding for 1-2 h to make the slurry fully fill the interconnected pores of the skeleton; Taking out the impregnated body, and drying at 60-80 ℃ for 12-24 h to remove free water; The S4: integrated sintering comprises: Placing the impregnated body in a graphite sintering furnace, and sintering in a nitrogen atmosphere with a pressure of 0.1-0.5 MPa: Low-temperature stage (room temperature-800 ℃): the heating rate is 5 ℃ / min, and the organic components in the body are removed; Medium-temperature stage (800-1600 ℃): the heating rate is 10 ℃ / min, and the sintering aids are melted to form a liquid phase; High-temperature stage (1600-1800 ℃): the heating rate is 5 ℃ / min, and the holding time is 2-4 h, at which time the silicon powder reacts in-situ with the skeleton surface to realize interface bonding between the skeleton and the base; S5: performance test: testing the prepared composite ceramic for bending strength, fracture toughness and 1200 ℃ creep resistance.