Preparation method of fiber-reinforced ceramic-based composite material

Abstract

The invention provides a preparation method of a fiber reinforced ceramic-based composite material, which comprises the following steps: S1) sealing a fiber preform by using a first vacuum bag film, and then sealing by using a second vacuum bag film to obtain a system to be impregnated; s2) placing the to-be-impregnated system in an autoclave, and vacuumizing the to-be-impregnated system; vacuumizing a precursor resin solution, introducing the vacuumized precursor resin solution into the to-be-impregnated system, and starting a pressurization program of the autoclave to perform pressurization impregnation; according to the preparation method provided by the invention, the fiber-reinforced ceramic matrix composite material is prepared by utilizing a combined process of RTM and an autoclave, an impregnation process is optimized, the number of times of a PIP process is reduced, and the purpose of rapidly and efficiently densifying the composite material is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of composite materials, and in particular to a method for preparing a fiber-reinforced ceramic-based composite material. Background Art

[0002] Fiber-reinforced ceramic matrix composites have excellent properties such as high strength, high toughness, high temperature resistance, good corrosion resistance and low density at high temperatures. They have broad application prospects in fields such as space technology and have been increasingly valued by material workers in recent years. For example, C / SiC composites are composed of carbon fiber preforms and silicon carbide matrix. During preparation, silicon carbide (SiC) matrix is ​​introduced into the carbon fiber preform to form a dense composite material. Since C / SiC composites are widely used in many fields and are important materials for the development of high-tech industries, it is increasingly meaningful to study efficient preparation methods for preparing C / SiC composites.

[0003] At present, there are many processes for preparing fiber-reinforced ceramic-based composites, mainly hot pressing, reactive sintering, direct melt oxidation, chemical vapor infiltration, sol-gel, precursor impregnation pyrolysis (PIP), etc. Among them, the precursor impregnation pyrolysis method is a more advanced and effective method, which has the advantages of simple process, low cost, and deep penetration. The prepared matrix is ​​uniform, and the pyrolysis temperature is relatively low, the damage to the carbon fiber is small, the composition of the matrix can be controlled, and the preparation of complex parts can be realized. Therefore, the fiber-reinforced polymer-based composites can be used to prepare preforms. An important process step in the preparation of fiber-reinforced ceramic-based composite preforms by the precursor impregnation pyrolysis method is the impregnation process. The quality of the impregnation process directly affects the densification of the material, thereby affecting the performance of the composite material.

[0004] The PIP method is a technology that uses precursor organic polymers to convert into ceramics to prepare ceramics and ceramic-based composites. However, a cracking reaction occurs during the pyrolysis of the precursor, in which a large amount of organic solvents are volatilized and low-density hydrocarbons escape. Before the final dense composite material is formed, multiple impregnation-cracking cycles are often required, which ultimately results in the number of PIP cycles being as high as more than ten times, resulting in a long preparation cycle for composite materials prepared by the PIP process; and the composite materials prepared by the PIP method have high porosity and large volume deformation.

[0005] Therefore, according to the engineering application needs of ceramic matrix composites, it is of great significance to shorten the preparation cycle of fiber-reinforced ceramic matrix composites, reduce the porosity of the composites and ensure dimensional stability. Summary of the invention

[0006] The technical problem solved by the present invention is to provide a method for preparing a fiber-reinforced ceramic-based composite material. The fiber-reinforced ceramic-based composite material provided by the present application has the characteristics of low porosity and high degree of densification, and can improve the impregnation efficiency; further, the preparation method provided by the present application can also prepare large-sized and complex-structured components.

[0007] In view of this, the present application provides a method for preparing a fiber-reinforced ceramic matrix composite material, comprising the following steps: S1) sealing the fiber preform with a first vacuum bag film, and then sealing it with a second vacuum bag film to obtain a system to be impregnated; S2) placing the system to be impregnated in an autoclave, and evacuating the system to be impregnated; The precursor resin solution is vacuumized, and then the vacuumized precursor resin solution is introduced into the system to be impregnated, and the pressurization program of the autoclave is started to perform pressurized impregnation; S3) starting a temperature rise curing procedure for curing, and then performing pyrolysis to obtain a fiber reinforced ceramic matrix composite material.

[0008] Preferably, the step S3) further includes: S4) Repeat step S2) and step S3) at least once.

[0009] Preferably, the method for preparing the fiber preform is specifically as follows: The fibers are needled, stitched or woven to obtain an initial fiber preform, wherein the volume density of the initial fiber preform is 0.3-1.1 g / cm 3 ; The initial fiber preform is subjected to chemical vapor infiltration to obtain a fiber preform having a pyrolytic carbon interface layer on the surface; The fiber is selected from one or more of carbon fiber T300, carbon fiber T700, carbon fiber M40 and silicon carbide fiber.

[0010] Preferably, the fiber preform is of regular shape or irregular shape.

[0011] Preferably, the system to be impregnated is evacuated to a vacuum degree of less than 100 Pa for 40 min to 80 min; and the precursor resin solution is evacuated for 20 to 60 min.

[0012] Preferably, the pressure of the pressurization procedure is 200-2000 kPa, and the time is 1-6 hours; the heating rate of the temperature-raising curing procedure is 0.5-5°C / min, the temperature is 80-200°C, and the heat preservation time is 1.5-5 hours.

[0013] Preferably, the heating rate of the pyrolysis is 3-10°C / min, the temperature is 900-1200°C, and the insulation time is 1-2h.

[0014] Preferably, the precursor resin solution is prepared as follows: Mixing a precursor resin and a curing agent to obtain a precursor resin solution; placing the precursor resin solution in a precursor resin providing device; Turning on the vacuum system of the precursor resin providing device to evacuate the precursor resin solution; The precursor resin is selected from one of polycarbosilane, polysiloxane, polynitrosilane and polyborosilazane, the curing agent is selected from dicumyl peroxide, and the mass ratio of the precursor resin to the curing agent is 1000: (1-10).

[0015] Preferably, step S2) is specifically as follows: S21) providing a first interface and a second interface on the first vacuum bag film, and providing a third interface on the second vacuum bag film; The first interface is connected to the interface of the precursor resin providing device through the first interface of the autoclave; The second interface is connected to an interface of a precursor resin collecting device through a second interface of the autoclave; The third interface is connected to the vacuum system of the autoclave; S22) opening the vacuum system of the precursor resin collecting device and the vacuum system of the autoclave to evacuate the precursor resin; S23) opening the precursor resin providing device to introduce the precursor resin solution into the system to be impregnated for impregnation, starting the pressurization procedure of the autoclave, and closing the precursor resin providing device after the precursor resin solution flows into the precursor resin collecting device.

[0016] Preferably, in step S4), step S2) and step S3) are repeated 4 to 7 times in sequence.

[0017] The present application provides a method for preparing a fiber-reinforced ceramic-based composite material, which first seals a fiber preform with a first vacuum bag film and a second vacuum bag film in sequence to obtain a system to be impregnated, then places the system to be impregnated in an autoclave, and evacuates it, and at the same time evacuates a precursor resin solution, then introduces the precursor resin solution into the system to be impregnated, and starts the pressurization program of the autoclave for pressurized impregnation; then performs curing and pyrolysis in sequence; that is, a fiber-reinforced ceramic-based composite material is obtained; in the method for preparing a fiber-reinforced ceramic-based composite material provided in the present application, the precursor resin solution is heated and pressurized by using an autoclave, which overcomes the flow resistance and improves its fluidity, and can drive the precursor resin solution to be impregnated into the fiber preform. At the same time, the precursor resin solution is impregnated into the fiber preform under pressure without dead ends in the autoclave. Since the autoclave is under uniform pressure, the pressure acting on the normal line of each point on the surface of the vacuum bag film is the same, which has obvious advantages over the traditional PIP method, can greatly improve the impregnation efficiency, and realizes the densification preparation of the composite material.

[0018] Furthermore, the method provided by the present invention shortens the PIP cycle, and the composite material can be densified through only 5 to 8 impregnation and cracking cycles; the present application utilizes vacuum bag film to seal the fiber preform, and uses the structurally variable and flexible vacuum bag film as a preparation model, so that the prepared composite material has the advantage of preparing large-sized and complex structural components. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the process for preparing the fiber-reinforced ceramic matrix composite material of the present invention; Figure 2 A simplified diagram of the structure of the device for preparing the fiber-reinforced ceramic matrix composite material of the present invention; Figure 3 This is a curve diagram of impregnation and cracking times-weight gain efficiency-open porosity in the process of preparing a fiber-reinforced ceramic matrix composite material in Example 2 of the present invention; Figure 4 This is a SEM photograph of the fiber-reinforced ceramic matrix composite material prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0020] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0021] In view of the problems of long cycle and low densification of the PIP process for preparing fiber-reinforced ceramic-based composite materials in the prior art, the present application provides a method for preparing fiber-reinforced ceramic-based composite materials, which utilizes a process combining resin transfer molding (RTM) process with an autoclave to impregnate the precursor resin solution in the system to be impregnated, and combines the heating and pressurizing function of the autoclave and the advantage of the fiber preform that can be laid in the RTM process to achieve efficient preparation of fiber-reinforced ceramic-based composite materials, and make the fiber-reinforced ceramic-based composite materials have a high degree of densification. Specifically, an embodiment of the present invention discloses a method for preparing a fiber-reinforced ceramic-based composite material, comprising the following steps: S1) sealing the fiber preform with a first vacuum bag film and then with a second vacuum bag to obtain a system to be impregnated; S2) placing the system to be impregnated in an autoclave, and evacuating the system to be impregnated; The precursor resin solution is vacuumized, and then the vacuumized precursor resin solution is introduced into the system to be impregnated, and the pressurization program of the autoclave is started to perform pressurized impregnation; S3) starting a temperature rise curing procedure for curing, and then performing pyrolysis to obtain a fiber reinforced ceramic matrix composite material.

[0022] In the preparation process of fiber reinforced ceramic matrix composite materials, the present application includes the following steps: preform preparation - CVI interface phase preparation - autoclave - RTM pressure impregnation - curing - cracking - repeated pressure impregnation, curing, cracking, such as Figure 1 As shown, Figure 1 A schematic diagram of the process for preparing fiber-reinforced ceramic matrix composite materials for this application.

[0023] According to the present invention, firstly, the raw material of fiber-reinforced ceramic matrix composite material is prepared. For the preparation of the initial fiber preform, two-dimensional stitched fibers, three-dimensional needle-punched fibers, and woven fibers can be used. The fibers are fibers well known to those skilled in the art. For example, the fibers are selected from one or more of carbon fiber T300, carbon fiber T700, carbon fiber M40, and silicon carbide fiber. The volume density of the initial fiber preform is 0.3~1.1g / cm 3 Specifically, the volume density of the initial fiber preform is 0.4-0.8 g / cm 3 More specifically, the volume density of the initial fiber preform is 0.6-0.7 g / cm 3 Then, the initial fiber preform is subjected to chemical vapor infiltration, that is, a pyrolytic carbon interface layer is prepared on the surface of the fiber preform by using a chemical vapor infiltration process, specifically: The fiber preform is placed in a CVI deposition furnace, evacuated to a vacuum degree of less than 200Pa, and then heated to 800-1500°C. Subsequently, a carbon source gas is introduced at a flow rate of 5-15L / min, the pressure in the furnace is controlled to be 0.5-20kPa, and the temperature is kept for 1-30h. Finally, a protective gas is introduced into the furnace, and the temperature is naturally lowered to room temperature under the protective atmosphere.

[0024] In the above process, specifically, the temperature is raised to 900-1300° C., the flow rate is 6-13 L / min, the pressure is 1-15 kPa, and the temperature is kept for 3-23 hours.

[0025] In the present application, the fiber preform may be of regular shape or irregular shape; the fiber preform may be a carbon fiber preform. The fiber preform used in the present application is preferably a fiber preform with a pyrolytic carbon interface layer prepared on the surface.

[0026] For the preparation of the precursor resin solution, which is used as an impregnation solution, the preparation method is specifically as follows: The precursor resin and the curing agent are mixed to obtain a precursor resin solution.

[0027] During the preparation of the precursor resin solution, the precursor resin is selected from one of polycarbosilane, polysiloxane, polynitrosilane and polyborosilazane, the curing agent is selected from diisopropylbenzene peroxide, and the mass ratio of the precursor resin to the curing agent is 1000: (1-10); specifically, the precursor resin is selected from polycarbosilane or polysiloxane, and the mass ratio of the precursor resin to the curing agent is 1000: (2-8), more specifically 1000: (3-6); the viscosity of the precursor resin solution is 30-100 mpa·s, specifically, the viscosity of the precursor resin solution is 50-80 mpa·s. The RTM-autoclave process provided in the present application is suitable for liquid precursor resins, wherein the addition of a curing agent is also beneficial to improving the ceramic yield, making the impregnation more compact, the porosity lower, and the preparation cycle greatly shortened, which is beneficial to rapid molding.

[0028] The present application then places the precursor resin solution in a precursor resin providing device, turns on the vacuum system of the precursor resin providing device to evacuate the precursor resin solution to remove the air in the precursor resin solution; if the viscosity of the precursor resin solution is relatively large, the precursor resin providing device is used to heat the precursor solution; the vacuuming time is 20 to 40 minutes, specifically, the vacuuming time is 25 to 35 minutes. The precursor resin providing device has the functions of vacuuming, pressurizing and heating. The pressurizing is used to introduce the precursor resin solution into the preform in the autoclave. The heating is used to reduce the viscosity of the precursor resin solution with higher viscosity and improve its fluidity. Specifically, the precursor resin providing device is a closed container with a pressure-resistant function. The outer wall of the container is equipped with a heating control unit, a vacuuming unit and a device for displaying the resin liquid level. It is connected to the air source of the autoclave or other independent air sources at the top, and there are a shut-off valve, a pressure regulating valve and a pressure display in the pipeline. It is connected to the resin introduction port on the wall of the autoclave at the bottom, and there is a switch valve in the pipeline. The upper and lower pipelines must be pressure-resistant pipelines.

[0029] After the above-mentioned preparatory work is completed, the present application seals the fiber preform prepared above with a first vacuum bag film and then with a second vacuum bag film, that is, the surface of the fiber preform is sealed with the first vacuum bag film and the second vacuum bag film in sequence. The vacuum bag film is a vacuum film well known to technicians in this field, which has the characteristics of good flexibility, large size, and arbitrarily adjustable structure. The vacuum bag film is used as a sealing model for the fiber preform, which can wrap the fiber preform as a whole, so that the precursor resin is subjected to a normal force without dead ends, thereby improving the impregnation driving force and being more conducive to the preparation of large-sized and complex-structured components; after the fiber preform is sealed with the first vacuum bag film and the second vacuum bag film, a system to be impregnated is obtained.

[0030] The present application then places the system to be impregnated in an autoclave. In addition to retaining all the functions of conventional autoclaves in the prior art, the autoclave also has a channel for the precursor resin solution to enter, a channel for the precursor resin solution to flow out, and a vacuum channel separated from the original vacuum pipeline. The precursor resin solution inlet channel is connected to the precursor resin providing device, the precursor resin solution outflow channel is connected to the precursor resin collecting device, and the vacuum channel is connected to the vacuum bag film; therefore, the autoclave should at least add 2 more channel interfaces at appropriate positions on the tank wall. Similarly, 3 interfaces are reserved on the vacuum bag film, the first vacuum bag film is provided with 2 interfaces, and the second vacuum bag film is provided with 1 interface; the 2 interfaces reserved for the first vacuum bag film are respectively connected to the 2 interfaces on the tank wall of the autoclave (these 2 interfaces are connected to the vacuum bag film inwardly, and one is connected to the precursor resin providing device and the other is connected to the precursor resin collecting device outwardly), and one interface of the second vacuum bag film is connected to the vacuum system of the autoclave; specifically, as Figure 2 As shown. The vacuum system of the autoclave is connected to the system to be impregnated in the autoclave through a vacuum pump, and there are vacuum buffer tanks and corresponding valves in the pipeline, which is a high-pressure resistant pipeline. The above-mentioned precursor resin collection device is a collection container for surplus resin, which is connected to the impregnation system on the autoclave. The pipeline material is a high-pressure resistant pipeline, and there should be a valve switch in the pipeline, which is opened during the vacuuming and precursor resin solution entering process, and closed when the entering process is completed.

[0031] After the interface of the autoclave is connected to the interface of the vacuum bag film, the interface of the precursor resin providing device, and the interface of the precursor resin collecting device, the vacuum system of the precursor resin collecting device and the vacuum system of the autoclave are turned on to evacuate the system to be impregnated to obtain a vacuum system to be impregnated with an internal negative pressure; the vacuuming time is 40 to 80 minutes, specifically, the vacuuming time is 50 to 70 minutes.

[0032] After the above vacuum treatment is completed, the flow of the precursor resin solution is controlled by the switch valve in the pipeline. First, the precursor resin solution is slowly introduced into the fiber preform through the vacuum negative pressure in the system to be impregnated. When the precursor resin solution flows into the precursor resin collection device connected to the vacuum pump, the switch valve through which the precursor resin solution flows out is closed, and a pressure of less than 100kpa is applied to the precursor resin providing device, so that the fiber preform in the first vacuum bag film is in the rich precursor resin solution, and then the precursor resin entry channel is closed to complete the first round of impregnation process. During the impregnation process, the pressurization program of the pressurization tank is turned on for pressurized impregnation; the pressure of the pressurization program is 0.2~2MPa, and the time is 1~6h; specifically, the pressure of the pressurization program is 0.2MPa~1.8MPa, and the time is 3~6h.

[0033] After the pressurized impregnation, the temperature rise curing program of the autoclave is started to cure and crosslink the precursor, and the temperature rise rate of the temperature rise curing program is 1~5℃ / min, the temperature is 80~200℃, and the temperature is kept for 1.5~5h; specifically, the temperature rise curing program is first increased to 80~140℃ at a temperature rise rate of 2~5℃ / min, kept for 1~2h, and then increased to 150~200℃ at a temperature rise rate of 0.5~1.5℃ / min, and kept for 2~3h.

[0034] According to the present invention, the cured fiber preform is then pyrolyzed; the heating rate of the pyrolysis is 3-10°C / min, the temperature is 900-1200°C, and the temperature is kept for 1-2 hours; specifically, the heating rate of the pyrolysis is 5-8°C / min, the temperature is 1000-1100°C, and then the temperature is lowered at 5-8°C / min, and the protective atmosphere of the pyrolysis is argon.

[0035] The present application finally repeats the above impregnation-curing-pyrolysis process at least once. Preferably, the impregnation-curing-pyrolysis process is performed 5 to 8 times to ensure that a densified fiber-reinforced ceramic-based composite material is obtained.

[0036] The present invention adopts a combined process of resin-based composite material molding process RTM combined with autoclave pressurization to prepare fiber-reinforced ceramic-based composite materials. The method is suitable for liquid precursor resin solution. Since the autoclave can apply pressure to the precursor resin solution, heat it, overcome flow resistance, and improve its fluidity, the precursor resin solution can be driven to be impregnated into the fiber preform impregnation system; the autoclave is used for heating and pressurization with equal pressure. The precursor resin solution is under pressure without dead angles in the autoclave, and the pressure acting on the normal line of each point on the surface of the vacuum bag film is also the same. Compared with the traditional PIP pressure impregnation method, it has obvious advantages and greater impregnation efficiency; at the same time, the vacuum bag film is used to seal the fiber preform, which has the advantage of preparing large-sized and complex components. The method combines the advantages of the two processes, introduces a new molding concept, combines the characteristics of high pressure and good quality of the autoclave with the advantages of RTM, and forms a liquid molding process method in which the three major process parameters of internal vacuum, external pressure and implementation temperature are independent and controllable. This method optimizes the impregnation process and reduces the number of PIP processes. The material can be densified through only 5 to 8 impregnation and pyrolysis cycles, achieving the purpose of fast and efficient densification of composite materials. It solves the problems of excessive impregnation and pyrolysis times, which damages fiber properties, and excessive product porosity and long preparation cycle.

[0037] In order to further understand the present invention, the preparation method of the fiber-reinforced ceramic-based composite material provided by the present invention is described in detail below in conjunction with examples, and the protection scope of the present invention is not limited by the following examples.

[0038] Example 1

[0039] S1: Preform weaving: Carbon fiber cloth and mesh fiber are laminated, and then normal fiber needle punching is performed, with a needle punching density of 30-35 needles / cm². The carbon fiber preform is first prepared into a preform with a shape close to or the same as the component, and fixed with a tooling. The component thickness is 10mm, the carbon fiber volume fraction is 35%, and the carbon fiber used is Toray T700; S2: Deposition interface layer: The woven carbon fiber preform is fixed on the tooling, placed in a CVI deposition furnace, and a pyrolytic carbon interface layer with a thickness of about 300 nm is prepared on the surface of the preform; S3: The silicon carbide organic precursor solution is impregnated using an autoclave-RTM process, specifically: Weigh a certain amount of liquid polycarbosilane resin, add dicumyl peroxide (DCP) at a mass ratio of 1000:3 and stir to make it completely dissolved in the polycarbosilane resin with a viscosity of 80-90 mPa.s; pour the obtained resin mixture into the resin tank, open the valve in the pipe connecting the resin tank and the vacuum pump, and evacuate for 1 hour to remove the air in the resin mixture for standby use; Use two layers of vacuum bag film to seal the carbon fiber preform with the deposited carbon interface layer, and reserve three interfaces on the vacuum bag film, two interfaces on the first layer of vacuum bag film, and one interface on the second layer; after the sealing is completed, transfer the preform together with the vacuum bag film into the autoclave, and then connect the two interfaces reserved on the first layer to the two interfaces on the wall of the autoclave respectively (these interfaces are the two interfaces after the autoclave is modified, and these two interfaces are connected to the interfaces on the vacuum bag film inwardly, and one is connected to the resin tank and the other is connected to the resin collection tank outwardly), and one interface on the second layer is connected to the vacuum pump of the autoclave; After the pipeline connection is completed, turn on the vacuum pump connected to the resin collection tank and the vacuum pump of the autoclave to evacuate for 1 hour, so that the vacuum degree of the vacuum bag film is less than 100 Pa, and keep it leak-proof for 10 minutes. At the same time, remove the air in the carbon fiber preform and all connecting pipelines to put the entire impregnation system in a vacuum environment; After the vacuum treatment, the valve of the resin tank is opened, and the negative pressure in the vacuum bag film is used to introduce the resin mixture to impregnate the carbon fiber preform. The pressurization program of the autoclave equipment is started for pressure impregnation, wherein the pressurization program is pressurized to 1.5MPa for 3 hours; after the resin continuously flows into the resin collection tank, the resin outflow valve is closed; S4: After the impregnation is completed, the heating program is turned on and the temperature is raised to 120-130°C at 3°C / min and kept at this temperature for 1 hour, and then the temperature is raised to 160°C at 0.5°C / min, kept at this temperature for 2 hours, and then cooled down for curing; S5: transferring the cured fiber preform to a high-temperature pyrolysis furnace, heating it to 1100°C at a rate of 5°C / min, keeping it at that temperature for 1h, and cooling it at a rate of 5°C / min, with argon as the protective atmosphere; S6: Impregnation-curing-cracking was repeated 8 times, and finally a Cf / SiC composite component was obtained. The Cf / SiC composite material was dense, with a component density of 2.15g / cm³ and an open porosity of 5%.

[0040] Example 2

[0041] S1: Prepare the precursor resin solution: weigh a certain amount of polycarbosilane precursor resin, add the curing agent DCP (diisopropylbenzene peroxide) in a mass ratio of 1000:3, and stir evenly to make the DCP completely dissolved; Pour the obtained precursor resin solution into the resin tank, open the valve in the pipeline connecting the resin tank and the vacuum pump, and evacuate for 1 hour to remove the air in the resin mixture for later use; S2: Carbon fiber preform preparation uses a carbon fiber needle punched preform with a volume density of 0.45g / cm³; The carbon fiber needle-punched preform is fixed on a fixture and placed in a CVI deposition furnace, and a 300nm thick pyrolytic carbon interface layer is prepared on the surface of the carbon fiber needle-punched preform; S3: The silicon carbide organic precursor solution is impregnated using an autoclave-RTM process, specifically: Use two layers of vacuum bag film to seal the carbon fiber preform with the deposited carbon interface layer, and reserve three interfaces on the vacuum bag film, two interfaces on the first layer of vacuum bag film, and one interface on the second layer; after the sealing is completed, transfer the preform together with the vacuum bag film into the autoclave, and then connect the two interfaces reserved on the first layer to the two interfaces on the wall of the autoclave respectively (these interfaces are the two interfaces after the autoclave is modified, and these two interfaces are connected to the interfaces on the vacuum bag film inwardly, and one is connected to the resin tank and the other is connected to the resin collection tank outwardly), and one interface on the second layer is connected to the vacuum pump of the autoclave; After the pipeline connection is completed, turn on the vacuum pump connected to the resin collection tank and the vacuum pump of the autoclave to evacuate for 1 hour, so that the vacuum degree of the vacuum bag film is less than 100 Pa, and keep it leak-proof for 10 minutes. At the same time, remove the air in the carbon fiber preform and all connecting pipelines to put the entire impregnation system in a vacuum environment; After the vacuum treatment, the valve of the resin tank is opened, and the negative pressure in the vacuum bag film is used to introduce the resin mixture to impregnate the carbon fiber preform. The pressurization program of the autoclave equipment is started for pressure impregnation, wherein the pressurization program is pressurized to 1.0 MPa for 3 hours; after the resin continuously flows into the resin collection tank, the resin outflow valve is closed; S4: After the impregnation is completed, the heating program is turned on and the temperature is raised to 120-130°C at 3°C / min and kept at this temperature for 1 hour, and then the temperature is raised to 160°C at 0.5°C / min, kept at this temperature for 2 hours, and then cooled down for curing; S5: transferring the cured fiber preform to a high-temperature pyrolysis furnace, heating it to 1100°C at a rate of 5°C / min, keeping it at that temperature for 1h, and cooling it at a rate of 5°C / min, with argon as the protective atmosphere; S6: Repeat impregnation-curing-cracking 8 times to finally obtain the Cf / SiC composite material.

[0042] The Archimedes drainage method was used to test the bulk density and open porosity. The measured density was 2.2 g / cm³ and the open porosity was 6.2%.

[0043] The weight gain efficiency and open porosity of each impregnation cracking process were tested, and the results are as follows: Figure 3 As shown by Figure 3 It can be seen that after 8 cycles, the weight gain efficiency dropped to less than 1%, and the open porosity dropped to 6.2%.

[0044] Figure 4 The SEM photo of the composite material prepared in this example is Figure 4 It can be seen that the composite material prepared in this embodiment has a densified structure.

[0045] Example 3

[0046] S1: Prepare the precursor resin solution: weigh a certain amount of polycarbosilane precursor resin, add the curing agent DCP (diisopropylbenzene peroxide) in a mass ratio of 1000:3, and stir evenly to make the DCP completely dissolved; Pour the obtained precursor resin solution into the resin tank, open the valve in the pipeline connecting the resin tank and the vacuum pump, and evacuate for 1 hour to remove the air in the resin mixture for later use; S2: Carbon fiber preform preparation uses a piece of carbon fiber needle punched preform with a volume density of 0.5g / cm³; The carbon fiber needle-punched preform is fixed on a fixture and placed in a CVI deposition furnace, and a 300nm thick pyrolytic carbon interface layer is prepared on the surface of the carbon fiber needle-punched preform; S3: The silicon carbide organic precursor solution is impregnated using an autoclave-RTM process, specifically: Use two layers of vacuum bag film to seal the carbon fiber preform with the deposited carbon interface layer, and reserve three interfaces on the vacuum bag film, two interfaces on the first layer of vacuum bag film, and one interface on the second layer; after the sealing is completed, transfer the preform together with the vacuum bag film into the autoclave, and then connect the two interfaces reserved on the first layer to the two interfaces on the wall of the autoclave respectively (these interfaces are the two interfaces after the autoclave is modified, and these two interfaces are connected to the interfaces on the vacuum bag film inwardly, and one is connected to the resin tank and the other is connected to the resin collection tank outwardly), and one interface on the second layer is connected to the vacuum pump of the autoclave; After the pipeline connection is completed, turn on the vacuum pump connected to the resin collection tank and the vacuum pump of the autoclave to evacuate for 1 hour, so that the vacuum degree of the vacuum bag film is less than 100 Pa, and keep it leak-proof for 10 minutes. At the same time, remove the air in the carbon fiber preform and all connecting pipelines to put the entire impregnation system in a vacuum environment; After the vacuum treatment, the valve of the resin tank is opened, and the negative pressure in the vacuum bag film is used to introduce the resin mixture to impregnate the carbon fiber preform. The pressurization program of the autoclave equipment is started for pressure impregnation, wherein the pressurization program is pressurized to 0.9MPa for 3h; after the resin continuously flows into the resin collection tank, the resin outflow valve is closed; S4: After the impregnation is completed, the heating program is turned on and the temperature is raised to 120-130°C at 3°C / min and kept at this temperature for 1 hour, and then the temperature is raised to 160°C at 0.5°C / min, kept at this temperature for 2 hours, and then cooled down for curing; S5: transferring the cured fiber preform to a high-temperature pyrolysis furnace, heating it to 1100°C at a rate of 5°C / min, keeping it at that temperature for 1h, and cooling it at a rate of 5°C / min, with argon as the protective atmosphere; S6: Repeat impregnation-curing-cracking 6 times to finally obtain the Cf / SiC composite material.

[0047] The volume density and open porosity of the Cf / SiC composite material obtained above were tested by the Archimedes drainage method, and the density was measured to be 2.1 g / cm³ and the open porosity was 8%.

[0048] Example 4

[0049] S1: Prepare the precursor resin solution: weigh a certain amount of polysiloxane precursor resin, add the curing agent DCP (diisopropylbenzene peroxide) according to the mass ratio of 1000:4, and stir evenly to make the DCP completely dissolved; Pour the obtained precursor resin solution into the resin tank, open the valve in the pipeline connecting the resin tank and the vacuum pump, and evacuate for 1 hour to remove the air in the resin mixture for later use; S2: Carbon fiber preform preparation uses a piece of carbon fiber needle punched preform with a volume density of 0.5g / cm³; The carbon fiber needle-punched preform is fixed on a fixture and placed in a CVI deposition furnace, and a pyrolytic carbon interface layer with a thickness of 250 nm is prepared on the surface of the carbon fiber needle-punched preform; S3: The autoclave-RTM process is used to impregnate the silicon-oxygen-carbon organic precursor solution, specifically: Use two layers of vacuum bag film to seal the carbon fiber preform with the deposited carbon interface layer, and reserve three interfaces on the vacuum bag film, two interfaces on the first layer of vacuum bag film, and one interface on the second layer; after the sealing is completed, transfer the preform together with the vacuum bag film into the autoclave, and then connect the two interfaces reserved on the first layer to the two interfaces on the wall of the autoclave respectively (these interfaces are the two interfaces after the autoclave is modified, and these two interfaces are connected to the interfaces on the vacuum bag film inwardly, and one is connected to the resin tank and the other is connected to the resin collection tank outwardly), and one interface on the second layer is connected to the vacuum pump of the autoclave; After the pipeline connection is completed, turn on the vacuum pump connected to the resin collection tank and the vacuum pump of the autoclave to evacuate for 1 hour, so that the vacuum degree of the vacuum bag film is less than 100 Pa, and keep it leak-proof for 10 minutes. At the same time, remove the air in the carbon fiber preform and all connecting pipelines to put the entire impregnation system in a vacuum environment; After the vacuum treatment, the valve of the resin tank is opened, and the negative pressure in the vacuum bag film is used to introduce the resin mixture to impregnate the carbon fiber preform. The pressurization program of the autoclave equipment is started for pressure impregnation, wherein the pressurization program is pressurized to 1.5MPa for 4 hours; after the resin continuously flows into the resin collection tank, the resin outflow valve is closed; S4: After the impregnation is completed, the heating program is turned on and the temperature is raised to 120-130°C at 3°C / min and kept at this temperature for 1 hour, and then the temperature is raised to 160°C at 0.5°C / min, kept at this temperature for 2 hours, and then cooled down for curing; S5: transferring the cured fiber preform to a high-temperature pyrolysis furnace, heating it to 1000°C at a rate of 5°C / min, keeping it at that temperature for 1h, and cooling it at a rate of 5°C / min, with argon as the protective atmosphere; S6: Repeat the impregnation-curing-cracking process 7 times to finally obtain the Cf / SiOC composite material.

[0050] The volume density and open porosity of the Cf / SiOC composite material prepared above were tested by the Archimedes drainage method, and the measured density was 1.9 g / cm³ and the open porosity was 5%.

[0051] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0052] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a fiber-reinforced ceramic matrix composite material, comprising the following steps: S1) sealing the fiber preform with a first vacuum bag film, and then sealing it with a second vacuum bag film to obtain a system to be impregnated; S2) placing the system to be impregnated in an autoclave, and evacuating the system to be impregnated; The precursor resin solution is vacuumized, and then the vacuumized precursor resin solution is introduced into the system to be impregnated, and the pressurization program of the autoclave is started to perform pressurized impregnation; S3) starting a temperature rise curing procedure for curing, and then performing pyrolysis to obtain a fiber reinforced ceramic matrix composite material.

2. The preparation method according to claim 1, characterized in that: The step S3) further includes: S4) Repeat step S2) and step S3) at least once.

3. The preparation method according to claim 1 or 2, characterized in that: The preparation method of the fiber preform is specifically as follows: The fibers are needled, stitched or woven to obtain an initial fiber preform, wherein the volume density of the initial fiber preform is 0.3-1.1 g / cm 3 ; The initial fiber preform is subjected to chemical vapor infiltration to obtain a fiber preform having a pyrolytic carbon interface layer on the surface; The fiber is selected from one or more of carbon fiber T300, carbon fiber T700, carbon fiber M40 and silicon carbide fiber.

4. The preparation method according to claim 1 or 2, characterized in that: The fiber preform is in a regular shape or an irregular shape.

5. The preparation method according to claim 1 or 2, characterized in that: The system to be impregnated is evacuated to a vacuum degree of less than 100 Pa for 40 minutes to 80 minutes; and the precursor resin solution is evacuated for 20 minutes to 60 minutes.

6. The preparation method according to claim 1 or 2, characterized in that: The pressure of the pressurization procedure is 200-2000 kPa, and the time is 1-6 hours; the heating rate of the temperature-raising curing procedure is 0.5-5°C / min, the temperature is 80-200°C, and the heat preservation is 1.5-5 hours.

7. The preparation method according to claim 1 or 2, characterized in that: The heating rate of the pyrolysis is 3-10°C / min, the temperature is 900-1200°C, and the heat preservation time is 1-2h.

8. The preparation method according to claim 1 or 2, characterized in that: The preparation of the precursor resin solution is specifically as follows: Mixing a precursor resin and a curing agent to obtain a precursor resin solution; placing the precursor resin solution in a precursor resin providing device; Turning on the vacuum system of the precursor resin providing device to evacuate the precursor resin solution; The precursor resin is selected from one of polycarbosilane, polysiloxane, polynitrosilane and polyborosilazane, the curing agent is selected from dicumyl peroxide, and the mass ratio of the precursor resin to the curing agent is 1000: (1-10).

9. The preparation method according to claim 8, characterized in that: Step S2) is specifically as follows: S21) providing a first interface and a second interface on the first vacuum bag film, and providing a third interface on the second vacuum bag film; The first interface is connected to the interface of the precursor resin providing device through the first interface of the autoclave; The second interface is connected to an interface of a precursor resin collecting device through a second interface of the autoclave; The third interface is connected to the vacuum system of the autoclave; S22) opening the vacuum system of the precursor resin collecting device and the vacuum system of the autoclave to evacuate the precursor resin; S23) opening the precursor resin providing device to introduce the precursor resin solution into the system to be impregnated for impregnation, starting the pressurization procedure of the autoclave, and closing the precursor resin providing device after the precursor resin solution flows into the precursor resin collecting device.

10. The preparation method according to claim 2, characterized in that: In step S4), step S2) and step S3) are repeated 4 to 7 times in sequence.

Images