Preparation method of high-strength Cf / SiC composite material based on low-texture PyC interface phase

Abstract

The invention discloses a preparation method of a high-strength Cf / SiC composite material based on a low-texture PyC interface phase, and belongs to the technical field of material preparation. The method comprises the following steps: firstly, placing a carbon fiber preform in a graphite mold, then placing the graphite mold in a CVI furnace body, connecting the graphite mold into a CVI gas path system, and gradually heating a furnace chamber to a specific temperature; and after the temperature of the furnace chamber is stable, methane is introduced into the furnace chamber, specific CVI deposition parameters are set, operation is conducted for 0.5-2 h, and the loose and porous low-texture PyC interface phase with the thickness of 100-500 nm is prepared. Thirdly, CVI deposition parameters for depositing the SiC substrate are adjusted, trichloromethylsilane, hydrogen and nitrogen with the specific flow are introduced into the furnace chamber, and operation is conducted for 8-120 h; finally, all precursor gas sources are closed, the sample is gradually cooled to the room temperature in the nitrogen atmosphere, and preparation of the high-strength Cf / SiC composite material is completed. The core innovation point of the invention is that a loose and porous low-texture PyC interface phase is prepared in the Cf / SiC composite material, so that the prepared Cf / SiC composite material has better mechanical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of material preparation, and particularly to a method for preparing a high-strength C f / SiC composite material. Background Technique

[0002] Carbon fiber reinforced silicon carbide (C f / SiC) composite materials have important applications in the aerospace field due to their advantages such as light weight, high specific strength, high temperature resistance, and ablation resistance, including thermal protection on the surface of hypersonic aircraft, aircraft nose cones, engine nozzles, etc. High mechanical property C f / SiC composite materials can reduce the usage amount (thickness or volume) of thermal protection materials, increase the effective space inside the aircraft, and truly achieve the integration of thermal protection and load-bearing. In C f / SiC composite materials, the PyC interface phase is one of the most common and widely used interface phase materials, which significantly affects the mechanical properties of the composite materials. However, current research on the design and study of the PyC interface phase mainly focuses on regulating its thickness and heat treatment, etc., and generally ignores the microstructure differences of the PyC interface phase itself.

[0003] This patent starts from regulating the microstructure of the PyC interface phase, designs and prepares a PyC interface phase with a specific microstructure, aiming to significantly improve the mechanical properties of C f / SiC composite materials. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing a high-strength C f / SiC composite material to solve the problems existing in the background technique.

[0005] To achieve the above purpose, the present invention provides a method for preparing a high-strength C f / SiC composite material based on a low-texture PyC interface phase. The core method is to deposit a loose and porous low-texture PyC interface phase on the surface of carbon fibers.

[0006] Preferably, it specifically includes the following steps:

[0007] S1. Place the carbon fiber preform in a confined graphite mold, place the graphite mold in the CVI furnace body, connect the graphite mold to the CVI gas path system, and gradually heat it up in a nitrogen atmosphere;

[0008] S2. Deposit the low-texture PyC interface phase: Introduce pure methane as the only deposition gas source and regulate the CVI process parameters for depositing the PyC interface phase;

[0009] S3. Deposit the SiC interfacial phase: Set the deposition parameters of the CVI process for depositing the SiC interfacial phase, and introduce trichloromethylsilane, hydrogen, and nitrogen, where trichloromethylsilane serves as the deposition gas source;

[0010] S4. Stop introducing the gas source, and then introduce nitrogen, and cool to room temperature in a nitrogen environment.

[0011] Preferably, in S1, the carbon fiber preform is any one of one-dimensional carbon fiber bundles, two-dimensional carbon fiber cloth, or three-dimensional carbon fiber braids.

[0012] Preferably, in S2, the CVI deposition parameters for depositing the low-texture PyC interfacial phase are: deposition temperature 1150 °C, deposition pressure 5 kPa, and deposition time 0.5 - 2 h.

[0013] Preferably, in S2, the gas residence time of methane is 0.05 s.

[0014] Preferably, in S2, the thickness of the loose and porous low-texture PyC is 100 - 500 nm.

[0015] Preferably, in S3, the CVI deposition parameters for depositing the SiC interfacial phase are: deposition temperature 1000 °C, deposition pressure 5 kPa, and deposition time 8 - 120 h.

[0016] Preferably, in S3, the gas flow rate of trichloromethylsilane is 0.3 mL / min.

[0017] Preferably, in S3, the gas flow rate of hydrogen is 250 mL / min.

[0018] Preferably, in S3, the gas flow rate of nitrogen is 250 mL / min.

[0019] On the one hand, the loose and porous low-texture PyC interfacial phase can both weaken the interface of the C f / SiC composite material, avoid stress concentration of carbon fibers, and can also bridge the defects on the surface of carbon fibers to avoid brittle fracture of carbon fibers under low stress. On the other hand, the thickness of the low-texture PyC interfacial phase should not be less than 100 nm nor more than 500 nm, otherwise it will lead to too strong or too weak an interface, which is not conducive to maximizing the mechanical properties of the C f / SiC composite material.

[0020] Therefore, the preparation method of a high-strength C f / SiC composite material of the present invention has the following beneficial effects:

[0021] (1) The preparation process of the present invention is simple, and the preparation of the loose and porous low-texture PyC interfacial phase can be realized in a conventional CVI deposition system;

[0022] (2) The C f / SiC composite material prepared by the present invention has significantly improved mechanical properties, and its tensile strength has increased by more than 30% compared to the current mechanical property level of the existing C f / SiC composite material.

[0023] The technical solution of the present invention will be further described in detail below with reference to the drawings and embodiments. Description of the Drawings

[0024] Figure 1 It is a cross-sectional morphology diagram of the PyC interface phase prepared in Example 1 of the present invention;

[0025] Figure 2 It is a physical diagram of the 1D mini-C f / SiC composite material prepared in Example 1 of the present invention;

[0026] Figure 3 It is a stress-strain curve of the 1D mini-C f / SiC composite material prepared in Example 1 of the present invention;

[0027] Figure 4 It is the cross-sectional morphology of the PyC interface phase prepared in Example 2 of the present invention;

[0028] Figure 5 It is a physical diagram of the 3D laminated stitched-C f / SiC composite material prepared in Example 2 of the present invention;

[0029] Figure 6 It is a stress-strain curve of the 3D laminated stitched-C f / SiC composite material prepared in Example 2 of the present invention. Detailed Embodiments

[0030] The present invention provides a method for preparing a high-strength C f / SiC composite material, which specifically includes the following steps:

[0031] S1. Place the carbon fiber preform in the CVI furnace body and ensure the correct assembly of the gas path, and then set a specific heating program; wherein, the carbon fiber preform is any one of one-dimensional carbon fiber bundles, two-dimensional carbon fiber cloths, or three-dimensional carbon fiber braids.

[0032] S2. Prepare a low-texture PyC interface phase: Set the deposition parameters of the CVI process, wherein the deposition temperature is 1150 °C, the deposition pressure is 5 kPa, pure methane is introduced as the deposition gas source, the residence time of methane is 0.05 s, and the deposition time is 0.5 - 2 h. The residence time of methane gas is controlled by the flow rate of methane. The greater the flow rate of methane, the shorter the residence time of methane in the mold.

[0033] The PyC interface phase obtained in this step is a loose and porous low-texture PyC, and the thickness of the PyC interface phase is 100 - 500 nm.

[0034] S3. Prepare the SiC interface phase: Change the deposition parameters of the CVI process, lower the deposition temperature to 1000 °C, the deposition pressure is 5 kPa, and introduce trichloromethylsilane, hydrogen, and nitrogen. Among them, trichloromethylsilane is used as the deposition gas source, the gas flow rate of trichloromethylsilane is 0.3 mL / min, the gas flow rates of hydrogen and nitrogen are both 250 mL / min, and the deposition time is 8 - 120 h. When the carbon fiber preform is a one-dimensional carbon fiber bundle, the deposition time is 9 - 20 h; when the carbon fiber preform is a two-dimensional carbon fiber cloth or a three-dimensional carbon fiber braid, the deposition time is extended to 20 - 120 h.

[0035] S4. Stop introducing all the precursor gas sources, and set a cooling program to gradually cool the sample to room temperature in a nitrogen environment.

[0036] The technical solutions of the present invention will be further described below through the accompanying drawings and embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention. In addition, it should be understood that after reading the content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application and all belong to the protection scope of the present invention.

[0037] As used herein, "embodiment" means that the specific features, structures, or characteristics described in connection with the embodiment may be included in at least one embodiment of the present application. The term "embodiment" that appears in various positions in the specification does not necessarily refer to the same embodiment, nor does it particularly limit its independence or relevance to other embodiments. In principle, in the present application, as long as there is no technical contradiction or conflict, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0038] Unless otherwise defined, the meanings of the technical terms used herein are the same as those commonly understood by those skilled in the technical field to which this application belongs; the use of relevant terms herein is only for describing specific embodiments and is not intended to limit this application.

[0039] In the present invention, unless otherwise specified, the reagents, instruments, equipment, etc. used are all the reagents, instruments, and equipment commonly used by those skilled in the art in this field.

[0040] Example 1

[0041] This embodiment provides a method for preparing a high-strength C f / SiC composite material, and the specific steps are as follows:

[0042] Place a one-dimensional carbon fiber bundle (1D mini carbon fiber bundle) in a small graphite mold, and connect the fiber bundle and the graphite mold to the gas path system of a chemical vapor deposition furnace (CVI). Gradually heat the furnace body to 1150 °C under a nitrogen atmosphere. Then, set the deposition pressure to 5 kPa, introduce pure methane as the deposition gas source, with a gas residence time of 0.05 s (methane flow rate 695 mL / min), and deposit for 2 h. Then adjust the temperature of the furnace body to 1000 °C, introduce trichloromethylsilane, hydrogen, and nitrogen, set the flow rate of trichloromethylsilane to 0.3 mL / min, and the flow rates of hydrogen and nitrogen to 250 mL / min each, and deposit for 8 h. After the deposition is completed, turn off all precursor gas sources and let the sample cool down to room temperature gradually under a high-temperature nitrogen atmosphere. The cross-sectional morphology diagram of the PyC interface phase after deposition and the sample diagram of the finally obtained 1D mini-C f / SiC composite material are respectively as Figure 1 and Figure 2 shown.

[0043] As Figure 1 can be seen, the PyC interface phase prepared in this embodiment is a loose and porous low-texture PyC, and its thickness is about 500 nm.

[0044] The stress-strain curve of the mini-C f / SiC composite material prepared in this embodiment is as Figure 3 shown. As Figure 3 can be seen, the mechanical properties of the 1D mini-C f / SiC composite material prepared according to this process are 862 MPa, significantly better than the current level (the mechanical properties of the current mini-C f / SiC composite material generally do not exceed 600 MPa).

[0045] Example Two

[0046] This embodiment provides a method for preparing a high-strength C f / SiC composite material, and the specific steps are as follows:

[0047] Place the 3D laminated stitched carbon fiber preform in a medium - large graphite mold, and connect the graphite mold to the gas path system of a chemical vapor deposition furnace (CVI). Gradually heat the furnace body to a specific temperature of 1150 °C in a nitrogen atmosphere in the furnace chamber. Then, set the deposition pressure to 5 kPa, introduce pure methane as the deposition gas source and set the gas residence time to 0.05 s (methane flow rate 1500 mL / min), and deposit for 25 min. Then adjust the temperature of the furnace body to 1000 °C, introduce trichloromethylsilane, hydrogen, and nitrogen, set the flow rate of trichloromethylsilane to 0.3 mL / min, and the flow rates of hydrogen and nitrogen are both 250 mL / min, and deposit for 120 h. After the deposition is completed, turn off all precursor gas sources and let the sample cool down to room temperature gradually in a high - temperature nitrogen atmosphere. The cross - sectional morphology diagram of the PyC interface phase after deposition and the sample diagram of the finally obtained 3D laminated stitched C f / SiC composite are as Figure 4 and Figure 5 shown.

[0048] As Figure 4 shown, at the current deposition time, the thickness of the loose and porous low - texture PyC interface phase prepared in this example is about 100 nm.

[0049] The stress - strain curve of the 3D laminated stitched - C f / SiC composite prepared in this example is as Figure 6 shown. From Figure 6 it can be seen that the mechanical properties of the 3D laminated stitched - C f / SiC composite prepared according to this process are 420 MPa, which is significantly better than the current level (250 - 300 MPa).

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A high-strength C based on a low-textured PyC interface phase f A method for preparing a SiC composite material, characterized in that: A loose, porous, low-textured PyC interphase is deposited on the carbon fiber surface.

2. A high strength C based on a low texture PyC interface phase according to claim 1. f A method for preparing a SiC composite material, characterized in that: The specific steps include: S1. Placing the carbon fiber preform in a confined graphite mold, placing the graphite mold in a CVI furnace, connecting the graphite mold to the CVI gas system and gradually heating it up under a nitrogen atmosphere; S2, deposition of low-texture PyC interface phase: pure methane is introduced as the only deposition gas source, and the CVI process parameters for deposition of PyC interface phase are regulated; S3, depositing SiC interface phase: setting deposition parameters of the CVI process for depositing SiC interface phase, introducing trichloromethylsilane, hydrogen and nitrogen, wherein trichloromethylsilane is used as a deposition gas source; S4. Stop the gas supply, then supply nitrogen, and cool to room temperature under a nitrogen environment.

3. A high strength C based on a low texture PyC interface phase according to claim 2. f A method for preparing a SiC composite material, characterized in that: In S1, the carbon fiber preform is any one of a one-dimensional carbon fiber bundle, a two-dimensional carbon fiber cloth, or a three-dimensional carbon fiber braid.

4. A high strength C based on a low texture PyC interface phase according to claim 2 f A method for preparing a SiC composite material, characterized in that: In S2, the CVI deposition parameters for depositing the PyC interface phase are: deposition temperature 1150°C, deposition pressure 5 kPa, and deposition time 0.5-2 h.

5. A high strength C based on a low texture PyC interface phase according to claim 2 f A method for preparing a SiC composite material, characterized in that: In S2, the gas residence time of methane is 0.05 s.

6. A high strength C based on a low texture PyC interface phase according to claim 2 f A method for preparing a SiC composite material, characterized in that: In S2, the prepared PyC interface phase is a loose, porous, low-textured PyC interface phase, and its thickness is 100-500 nm.

7. A high strength C based on a low texture PyC interface phase according to claim 2. f A method for preparing a SiC composite material, characterized in that: In S3, the CVI deposition parameters for depositing the SiC interface phase are set as follows: deposition temperature 1000°C, deposition pressure 5 kPa, and deposition time 8-120 h.

8. A high strength C based on a low texture PyC interface phase according to claim 2 f A method for preparing a SiC composite material, characterized in that: In S3, the gas flow rate of trichloromethylsilane was 0.3 mL / min.

9. A high strength C based on a low texture PyC interface phase according to claim 2 f A method for preparing a SiC composite material, characterized in that: In S3, the gas flow rate of hydrogen was 250 mL / min.

10. A high strength C based on a low texture PyC interface phase according to claim 2 f A method for preparing a SiC composite material, characterized in that: In S3, the gas flow rate of nitrogen was 250 mL / min.

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