CN116396088A

CN116396088A - Method for improving melt siliconizing uniformity of MI-SiC/SiC preform and interlayer binding force of composite material

Info

Publication number: CN116396088A
Application number: CN202310361648.0A
Authority: CN
Inventors: 马付根
Original assignee: Hefei Fuweikang New Materials Co ltd
Current assignee: Hefei Fuweikang New Materials Co ltd
Priority date: 2023-04-03
Filing date: 2023-04-03
Publication date: 2023-07-07

Abstract

The invention discloses a method for improving the melt siliconizing uniformity of an MI-SiC/SiC preform and the interlayer binding force of a composite material, which aims to solve the technical problems of uneven siliconizing of large-size complex components and weaker interlayer binding force of the composite material, and adopts the technical scheme that: preparing fiber prepreg cloth or unidirectional prepreg tape, laminating, forming to obtain a preform, needling to obtain a preform with a needled array, curing in an autoclave, performing high-temperature heat treatment, and performing melt siliconizing in high-temperature vacuum to obtain the MI-SiC/SiC composite material. According to the invention, the carbon fiber wick matrix is introduced into the SiC fiber preform by utilizing the needling technology, so that the siliconizing points of the preform are increased, the siliconizing is not limited by the size and shape of the component by controlling the spacing of the needled carbon fiber wicks, and the difficult problem of uneven siliconizing or insufficient siliconizing of the large-size complex component is effectively solved.

Description

Method for improving melt siliconizing uniformity of MI-SiC/SiC preform and interlayer binding force of composite material

Technical Field

The invention belongs to the technical field of preparation of ceramic matrix composite materials, and particularly relates to a method for improving melt siliconizing uniformity of MI-SiC/SiC preforms and interlayer binding force of composite materials.

Background

The continuous fiber reinforced ceramic matrix composite material has the outstanding advantages of high temperature resistance, high specific strength and high specific modulus, has fracture characteristics similar to metals, and has high reliability, thus becoming novel aerospace heatEmergency material for structural member and nuclear industry radiation-resistant memberResearch on application of fiber-toughened high-temperature ceramic matrix composite (C, siC/SiC) by sand construction army, auspicious replacement and Zhang Zhaofu Advances, aeronautical manufacturing techniques, 2017)。

At present, the continuous silicon carbide fiber reinforced silicon carbide ceramic matrix composite (SiC/SiC) is one of the structural materials with the most excellent high temperature resistance. The preparation method of the material mainly comprises the following steps ofLiu Hu, yang Jinhua, jiao Jian, aircraft engine coupling Continuous SiC/SiC composite material preparation process and application prospect, aviation manufacturing technology and 2017): chemical vapor infiltration (Chemical Vapor Infiltration, CVI), melt infiltration (Melt Infiltration, MI), nano-infiltration transient eutectic (Nano-Infiltration and Transient Eutectic, NITE), sol-Gel (Sol-Gel), precursor dip cracking (Precursor Impregnationand Pyrolysis, PIP), CVI+PIP, and NITE+PIP.

Among these technologies, the SiC/SiC composite material (MI-SiC/SiC) prepared by the MI process has the performance advantages of low porosity, high thermal conductivity, high interlaminar shear strength, etc., and the process has the outstanding advantages of short preparation period and low cost, so that it has been applied to manufacture of aero-engines and industrial gas turbine hot end components abroad.

The universal electric (GE) company in the United states developed a unidirectional Prepreg tape-infiltration (Prepreg-MI) process and developed to

Is a brand MI-SiC/SiC composite material product which has been successfully applied to turbine outer rings, combustion chambers and other hot junction components of aeroengines and industrial gas turbinesDong Shaoming, hu Jianbao, zhang Xiangyu, siC/SiC composite MI process Preparation technique, aeronautical manufacturing technique, 2014,6). The unidirectional prepreg tape-MI process mainly comprises the following steps: (1) Firstly, preparing an interface layer on the surface of SiC fiber by adopting a Chemical Vapor Deposition (CVD) technology; (2) Mixing SiC powder, carbon powder, a resin binder, a surfactant and a solvent to prepare ceramic slurry, immersing the slurry into a fiber bundle with a coating, and winding the fiber bundle by a wet method to form a SiC fiber unidirectional prepreg tape; (3) Unidirectional pre-heatingThe immersed layer is stacked to form a composite material preform, and then the composite material preform is solidified to realize shaping; (4) Carbonizing the resin by pyrolysis, and discharging other organic components in a gaseous state to form a preform with a large number of micropores, so as to provide a channel for subsequent siliconizing; (5) And finally, heating the silicon powder or the silicon block to a molten state (higher than 1410 ℃), and allowing liquid silicon to infiltrate into the porous fiber preform under the action of capillary force, so that silicon carbide is generated by the reaction of silicon and carbon, and the compact MI-SiC/SiC composite material is prepared.

NASA developed a slurry casting-infiltration (SlurryCast-MI) process and formed multiple brands of ceramic matrix composite products, such as N22, N24, etc. (-)Dong Shaoming, hu Jianbao, zhang Xiangyu, siC/SiC composite material MI technique, aviation manufacturing technology, 2014,6). The slurry casting-infiltration process comprises the following steps: (1) Firstly, laminating and forming SiC fiber cloth to obtain a composite material preform; (2) adopting CVI technology to prepare an interface layer on the surface of the fiber; (3) Depositing a SiC protective layer on the surface of the interface layer by adopting a CVI technology so as to reduce corrosion of molten silicon to SiC fibers and surface coatings in the subsequent infiltration process; (4) Mixing SiC powder, a resin binder, a surfactant and a solvent to prepare ceramic slurry, immersing the slurry into the preform, then carbonizing the resin by pyrolysis, and discharging other organic components in a gaseous state to form a preform with a large number of micropores, so as to provide a channel for subsequent siliconizing; (5) And finally, heating the silicon powder or the silicon block to a molten state (higher than 1410 ℃), and allowing liquid silicon to infiltrate into the porous fiber preform under the action of capillary force, so that silicon carbide is generated by the reaction of silicon and carbon, and the compact MI-SiC/SiC composite material is prepared.

In the MI process described above, molten silicon enters the interior of the preform by capillary forces. Because molten silicon is strongly corrosive to SiC fibers and SiC fiber surface coatings, it is necessary to tightly control the siliconizing conditions to reduce the corrosive damage of liquid silicon to the fibers and coatings. Therefore, the temperature and time of the melt-siliconizing are strictly limited, and are generally 1410-1450 ℃ for 10-120 min. At this temperature, the silicon has a high viscosity and a high surface tension, which results in a limited penetration distance (typically within 50 mm) in the preform. In the MI process, liquid silicon reacts with carbon inside the matrix to produce SiC. The reaction formula is as follows:

Si(l)+C(s)＝SiC(s)

the generated SiC product can further obstruct the penetration of liquid silicon, so that the effective distance of siliconizing is further reduced. Therefore, how to adapt the melt siliconizing technology to the preparation of large-size MI-SiC/SiC components is one of the core problems of the technology for engineering applications.

At present, the research of MI-SiC/SiC composite materials is less related to how to solve the engineering technical problem of siliconizing large-size components. Patent CN112457027A 2020 @Wang Peng, zhao Bingbing, zhang Qian, zhang Hai, zhang Xi, wang Yan, li Jianzhang, large-sized circles Tool and method for melt siliconizing of cross-section ceramic matrix composite member) A siliconizing method for large-size cylindrical member features that multiple layers of graphite crucibles are arranged along the length direction of cylindrical member, and graphite paper is used to connect silicon source to prefabricated body. In the technology, the quality of siliconizing is affected by manual operation factors, such as the contact tightness of graphite paper and components, the filling density of silicon materials and the like, and a graphite crucible with complex shape is required to be processed aiming at different components, so that the process reliability is affected, and the cost is high; in addition, in order to ensure the sufficient penetration of silicon, the siliconizing temperature of the technology reaches 1650 ℃ and the time is as long as a plurality of hours, so that obvious corrosion damage and heat damage are generated on the coating and the SiC fiber, and the mechanical property of the composite material is obviously reduced.

Because the liquid silicon permeation distance is limited, when the MI technology is used for preparing the large-size MI-SiC/SiC composite material, the defect of insufficient local siliconizing is often generated at the position far away from the liquid silicon source. Shortening the penetration distance of liquid silicon can improve the uniformity of siliconizing and improve the quality of products. The penetration distance of molten silicon is shortened by the needling technology, the siliconizing condition can be obviously improved, and no related report is yet seen at present.

In addition, MI-SiC/SiC is prepared from prepreg lamination, so that the interlayer bonding force of the final composite material is weak, and the interlayer tensile strength is 30-40 MPa. When used as a hot end component, the component has a large temperature gradient in the thickness direction, and interlayer shearing or tensile failure of the composite material is easy to occur. Improving the interlayer binding force of the MI-SiC/SiC composite material can obviously improve the service life and the application range of the component, and research and development personnel in various countries list the component as key problems to be solved.

Disclosure of Invention

The invention aims to provide a method for improving the melt siliconizing uniformity of an MI-SiC/SiC preform and the interlayer binding force of a composite material so as to solve the technical problems.

The invention aims to solve the technical problems, and is realized by adopting the following technical scheme:

the utility model provides a method for improving MI-SiC/SiC preform fusion siliconizing uniformity and composite material interlayer bonding force, its frock that uses includes upper cover plate, bottom plate and a plurality of fastening bolt, a plurality of wick holes have evenly been seted up at upper cover plate middle part, upper cover plate and bottom plate all around pass through a plurality of fastening bolt fixed connection, upper cover plate and bottom plate's surface all spray coating boron nitride release agent;

the method comprises the following steps:

1) The continuous SiC fibers are made into fiber prepreg cloth or unidirectional prepreg tape A, and the method concretely comprises the following steps:

when preparing the fiber cloth, firstly weaving SiC fibers to obtain the fiber cloth, and preparing a fiber surface coating; soaking SiC fiber cloth with a fiber surface coating in ceramic slurry, taking out after full soaking, and drying to obtain prepreg cloth;

when preparing the unidirectional prepreg tape, firstly preparing a surface coating on SiC fiber bundle filaments, then enabling the fiber bundles to continuously pass through a ceramic slurry pool, and winding the fiber bundles with slurry on a roller to form the unidirectional prepreg tape;

2) Carrying out lamination forming on the fiber prepreg cloth or the unidirectional prepreg tape A to obtain a preform, carrying out needling by using a needling machine, and enabling carbon fibers to protrude out of the surface of the preform after needling to obtain a preform B with a needling array;

3) Sealing the B by using a vacuum bag, continuously vacuumizing the interior, and curing in an autoclave to obtain a cured preform C;

4) Performing heat treatment on the C in an inert atmosphere at a high temperature to carbonize the preform, thereby obtaining a carbonized preform D;

5) Placing the D on a bottom plate of the tool, covering an upper cover plate, enabling the protruding carbon fiber arrays to penetrate through lampwick holes, locking the upper cover plate and the bottom plate by using fastening bolts, uniformly paving silicon powder on the upper surface of the upper cover plate, and covering the protruding carbon fiber arrays;

6) And 5) placing the sample and the tool obtained in the step 5) in a siliconizing furnace, melting and siliconizing under vacuum, and then cooling to room temperature along with the furnace to obtain the MI-SiC/SiC composite material.

Preferably, in the step 1), the surface coating layer comprises BN coating with the thickness of 200nm-600nm and Si with the thickness of 100nm-500nm from the surface layer of the fiber outwards ₃ N ₄ A coating and a C coating with a thickness of 5nm-50 nm.

Preferably, in the step 1), the thickness of the single piece of prepreg cloth is 0.3mm-0.8mm, and the thickness of the single piece of unidirectional prepreg tape is 0.2mm-0.6mm.

Preferably, the ceramic slurry in the step 1) contains silicon carbide powder, carbon powder, a resin binder, a dispersant and a solvent.

Preferably, the solid content of the ceramic slurry is 20% -50%, wherein the granularity of the silicon carbide powder is 0.5-5 mu m, the granularity of the carbon powder is 0.1-5 mu m, and the resin binder is any one of epoxy resin, phenolic resin or furfural resin.

Preferably, in the step 2), 1K-3K carbon fiber bundles are used for needling, and the needling distance is 10mm-100mm; the needling length is 5mm-20mm, and the carbon fiber protrudes 3mm-5mm from the surface of the preform after needling.

Preferably, the curing pressure of the autoclave in the step 3) is 0.5MPa to 2MPa; the temperature is 80-150 ℃ and the heat preservation time is 0.5-10 h; the high-temperature carbonization in the step 4) is carried out in any inert atmosphere, the temperature is 900-1300 ℃, and the heat preservation time is 0.5-5 h.

Preferably, the upper cover plate, the fastening bolts and the bottom plate are all made of graphite.

Preferably, the temperature of the melt siliconizing in the step 6) is 1410-1450 ℃, and the siliconizing time is 1-60 min.

The beneficial effects of the invention are as follows:

1. according to the invention, the carbon fiber wick matrix is introduced into the SiC fiber preform by utilizing the needling technology, so that the siliconizing point of the preform is increased. The liquid silicon permeates from the carbon fiber lamp cores to the surrounding prefabricated body, so that the siliconizing distance is shortened. By controlling the spacing of the needle-punched carbon fiber lampwicks, siliconizing is not limited by the size and shape of the component, and the difficult problems of uneven siliconizing or insufficient siliconizing of large-size complex components are effectively solved;

2. the carbon fiber wick array can greatly shorten the silicon soaking time and reduce the corrosion of liquid silicon to SiC fibers, thereby guaranteeing the excellent mechanical properties of the MI-SiC/SiC composite material;

3. the compact columnar silicon carbide formed after the carbon fiber lamp wick and the liquid silicon react can obviously improve the interlayer bonding strength of the composite material;

4. the invention has simple process and low cost, is suitable for mass production of large-size complex components, and has the value of engineering application.

Drawings

FIG. 1 is a schematic illustration of needling of a fibrous preform according to the present invention;

FIG. 2 is an enlarged view of a portion of area A of FIG. 1;

FIG. 3 is a schematic diagram of the siliconizing tool and preform assembly of the present invention;

wherein: 1-carbon fiber bundle wire, 2-transmission gear, 3-felting needle, 4-SiC fiber preform, 5-fiber feeding device, 6-carbon fiber lamp wick, 7-upper cover plate, 8-fastening bolt, 9-bottom plate and 10-silica powder.

Detailed Description

In order that the manner in which the above recited features, objects and advantages of the present invention are obtained, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Based on the examples in the embodiments, those skilled in the art can obtain other examples without making any inventive effort, which fall within the scope of the invention.

Specific embodiments of the present invention are described below with reference to the accompanying drawings.

Example 1

The utility model provides a method for improving MI-SiC/SiC preform fusion siliconizing uniformity and composite material interlayer bonding force, its frock that uses includes upper cover plate 7, bottom plate 9 and four fastening bolts 8 that graphite was made, a plurality of wick holes that aperture is 2mm have evenly been seted up at upper cover plate 7 middle part, upper cover plate 7 and bottom plate 9 all around pass through four fastening bolts 8 fixed connection, upper cover plate 7 and bottom plate 9's surface all spray boron nitride release agent;

the method comprises the following steps:

1) The continuous SiC fibers are made into a unidirectional prepreg tape A, which is specifically as follows:

when preparing the unidirectional prepreg tape, firstly, preparing a BN coating with the thickness of 400nm and Si with the thickness of 400nm on SiC fiber bundle filaments from the fiber surface layer outwards in sequence ₃ N ₄ The coating and the C coating with the thickness of 30nm are coated, then the fiber bundle continuously passes through a ceramic slurry pool, the fiber bundle with the slurry is wound on a roller with the diameter of 600mm, and after the winding width reaches 400mm, the fiber bundle is sheared from the roller to obtain a unidirectional prepreg tape A with the width of 400mm, the length of 1884mm and the thickness of 0.4 mm;

the ceramic slurry contains 25wt.% of SiC powder, 0.8 μm of D50, 10wt.% of C powder, 0.1 μm of D50, 12wt.% of phenolic resin and curing agent, 3wt.% of dispersing agent Polyethylenimine (PEI) and absolute ethyl alcohol as solvent.

2) Cutting a unidirectional prepreg tape A into sheets with the length of 400mm multiplied by 400mm, laminating and forming 8 layers of sheets to obtain a preform, mutually perpendicular to the fiber directions of each adjacent layer, and carrying out needling by using a needling machine, wherein 1K carbon fiber bundles are used as lampwicks, the lampwick interval is 20mm, and the length of the needled carbon fibers is 15mm, so as to obtain a preform B with a lampwick matrix;

because part of solvent residues still remain in the laminated preform, not only a certain bonding force between layers is ensured, but also the resistance during needling can be reduced; in addition, the fiber bundles in the preform can also move to a certain extent, so that the damage of needling to the SiC fibers can be reduced. 1K-3K carbon fiber bundle wires are used for needling, and the needling interval is 10mm-100mm; the carbon fiber protrudes 3mm-5mm from the surface of the preform after the needling is performed, so that the carbon fiber can be fully contacted with liquid silicon during subsequent siliconizing, and a rapid channel of the liquid silicon is formed.

3) Sealing the B by using a vacuum bag, continuously vacuumizing the interior, and placing the B in an autoclave for curing at the pressure of 1.0MPa and the temperature of 135 ℃ for 2 hours to obtain a cured preform C;

in the process, the resin is solidified under the conditions of temperature and pressure, the porosity in the preform is reduced, and the microstructure uniformity and strength of the preform are greatly improved.

4) C is N at high temperature ₂ Performing heat treatment at 1100 ℃ for 2 hours in the atmosphere to carbonize the preform, thereby obtaining a carbonized preform D;

the inert atmosphere is nitrogen or argon, and in the process, the carbon-based resin adhesive is carbonized, gas byproducts are removed, and a large number of holes are introduced into the matrix, so that a passage is provided for subsequent melt siliconizing.

5) Placing the D on a bottom plate 9 of the tool, covering an upper cover plate 7, enabling the protruding carbon fiber array to penetrate through a lampwick hole, and locking the upper cover plate 7 and the bottom plate 9 by using a fastening bolt 8 so as to prevent a sample from deforming in the siliconizing process; silicon powder 10 is uniformly paved on the upper surface of the upper cover plate 7, and a protruding carbon fiber array is covered;

6) And 5) placing the sample and the tool obtained in the step 5) in a siliconizing furnace, heating to 1440 ℃ under 10Pa vacuum, preserving heat for 10min, and then cooling to room temperature along with the furnace to obtain the MI-SiC/SiC composite material.

When silicon is melted at high temperature, the silicon is sucked into the carbon fiber wick under the action of capillary force, and the molten silicon can quickly permeate and diffuse into surrounding prefabricated bodies because the pores of the carbon fibers are linear. Although the carbon fiber reacts with the liquid silicon to generate silicon carbide, a developed and unobstructed pore structure can be maintained to ensure the rapid transmission of the liquid silicon. After siliconizing is finished, the carbon fiber and liquid silicon react to be converted into SiC to become a part of a composite material matrix; the carbon in the SiC fiber preform layer also reacts with liquid silicon to convert to SiC, with other small voids being filled with liquid silicon.

The thickness of the BN coating can also be any value between 200nm and 600nm, si ₃ N ₄ The thickness of the coating may also be any value between 100nm and 500nm, and the thickness of the C coating may also be any value between 5nm and 50 nm.

The thickness of the monolithic unidirectional prepreg tape may also be any value between 0.2mm and 0.6mm.

The solid content of the ceramic slurry can be any value between 20 and 50 percent, the granularity of the silicon carbide powder can be any value between 0.5 and 5 mu m, the granularity of the carbon powder can be any value between 0.1 and 5 mu m, and the resin binder is any one of epoxy resin or furfural resin.

The carbon fiber bundle wires used in the needling in the step 2) can be any value between 1K and 3K, and the needling distance can be any value between 10mm and 100mm; the needling length can also be any value between 5mm and 20mm, and the surface of the carbon fiber protruding preform after needling can be any value between 3mm and 5mm.

The MI-SiC/SiC composite material obtained in the embodiment has the porosity of 3.3%, the volume fraction of SiC fibers of 22%, the tensile strength of the composite material of 249MPa, the fracture strain of 0.43% and the interlaminar tensile strength of 51MPa, and has excellent mechanical properties.

Comparative example

1) Step 1) as in example 1;

2) Cutting a unidirectional prepreg tape into sheets of 400mm×400mm, and laminating 8 sheets to form a preform, wherein the fiber directions of each adjacent layer are mutually perpendicular, unlike example 1 in which there is no needled carbon fiber wick;

3) Placing the preform into an autoclave for curing, wherein the pressure is 1.0MPa, the temperature is 135 ℃, and the time is 2 hours;

4) Step 4) of example 1;

5) The carbonized preform is assembled between two graphite sheets. Unlike example 1, the graphite sheet above was not perforated. When assembling, the prefabricated body is placed on the graphite plate, the silicon powder is paved on one side of the graphite plate and contacts one side of the prefabricated body, then the prefabricated body and the silicon powder are covered by the other graphite plate, and the graphite upper clamping plate and the graphite lower clamping plate are locked by utilizing the graphite bolts so as to prevent the sample from deforming in the siliconizing process. The inner surface of the graphite plate, which is in contact with the preform, is sprayed with a boron nitride release agent to prevent silicon powder from reacting with the graphite plate after melting and prevent the graphite plate from being bonded with the composite material after siliconizing the preform.

6) After assembly, placing the sample and the graphite tool in a siliconizing furnace, heating to 1440 ℃ under 10Pa vacuum atmosphere, preserving heat for 30min, and then cooling to room temperature along with the furnace to obtain the MI-SiC/SiC composite material.

Comparative example results the results show that when there is no needled carbon fiber wick array, although the siliconizing time is prolonged from 10min to 30min, the liquid silicon penetration distance from one side of the preform is only 65mm, and the rest is not substantially siliconized.

The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the above-described embodiments, and that the above-described embodiments and descriptions are only preferred embodiments of the present invention, and are not intended to limit the invention, and that various changes and modifications may be made therein without departing from the spirit and scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. The utility model provides a method for improving MI-SiC/SiC preform melt siliconizing uniformity and composite material interlayer bonding force, its frock that uses includes upper cover plate (7), bottom plate (9) and a plurality of fastening bolt (8), a plurality of wick holes have evenly been seted up at upper cover plate (7) middle part, upper cover plate (7) and bottom plate (9) all around pass through a plurality of fastening bolt (8) fixed connection, upper cover plate (7) and bottom plate (9) surface all spray boron nitride release agent;

the method is characterized by comprising the following steps of:

5) Placing the D on a bottom plate (9) of the tool, covering an upper cover plate (7), enabling the protruding carbon fiber array to penetrate through a lampwick hole, locking the upper cover plate (7) and the bottom plate (9) by using a fastening bolt (8), uniformly paving silicon powder (10) on the upper surface of the upper cover plate (7), and covering the protruding carbon fiber array;

2. The method for improving the uniformity of melt siliconizing and the interlayer bonding force of composite materials according to claim 1, wherein in the step 1), the surface coating comprises BN coating with the thickness of 200nm to 600nm and Si with the thickness of 100nm to 500nm from the surface layer of the fiber to the outside ₃ N ₄ A coating and a C coating with a thickness of 5nm-50 nm.

3. The method for improving the uniformity of melt siliconizing and the interlayer bonding force of composite materials according to claim 1, wherein in the step 1), the thickness of the single piece of prepreg cloth is 0.3mm-0.8mm, and the thickness of the single piece of unidirectional prepreg tape is 0.2mm-0.6mm.

4. The method for improving the melt siliconizing uniformity of the MI-SiC/SiC preform and the interlayer binding force of the composite material according to claim 1, wherein the ceramic slurry in the step 1) comprises silicon carbide powder, carbon powder, a resin binder, a dispersing agent and a solvent.

5. The method for improving the melt siliconizing uniformity and the interlayer binding force of a composite material of an MI-SiC/SiC preform according to claim 4, wherein the solid content of the ceramic slurry is 20% -50%, the granularity of the silicon carbide powder is 0.5-5 μm, the granularity of the carbon powder is 0.1-5 μm, and the resin binder is any one of epoxy resin, phenolic resin or furfural resin.

6. The method for improving the melt siliconizing uniformity of the MI-SiC/SiC preform and the interlayer binding force of the composite material according to claim 1, wherein 1K-3K carbon fiber bundles are used for needling in the step 2), and the needling distance is 10mm-100mm; the needling length is 5mm-20mm, and the carbon fiber protrudes 3mm-5mm from the surface of the preform after needling.

7. The method for improving the melt siliconizing uniformity of the MI-SiC/SiC preform and the interlayer binding force of the composite material according to claim 1, wherein the curing pressure of the autoclave in the step 3) is 0.5MPa to 2MPa; the temperature is 80-150 ℃ and the heat preservation time is 0.5-10 h; the high-temperature carbonization in the step 4) is carried out in any inert atmosphere, the temperature is 900-1300 ℃, and the heat preservation time is 0.5-5 h.

8. The method for improving the melt siliconizing uniformity of the MI-SiC/SiC preform and the interlayer binding force of the composite material according to claim 1, wherein the upper cover plate (7), the fastening bolts (8) and the bottom plate (9) are all made of graphite.

9. The method for improving the uniformity of melt siliconizing and the interlayer bonding force of composite materials according to claim 1, wherein the melt siliconizing temperature in the step 6) is 1410-1450 ℃ and the siliconizing time is 1-60 min.