CN117602957A - A kind of preparation method of C/SiC composite material - Google Patents

Abstract

The invention belongs to the technical field of preparation of aerospace thermostructural materials, and particularly discloses a preparation method of a C/SiC composite material. The preparation method of the invention uses the C fiber preform as a reinforcing phase, uses PCS/VHPCS complex phase precursor slurry as a first impregnant, and carries out a first round of PIP cyclic densification treatment to prepare an intermediate; and performing a second round of PIP cyclic densification treatment on the prepared intermediate by taking the polymer silicon carbide precursor without powder as a second impregnant to prepare the C/SiC composite material. The preparation method effectively shortens the preparation period of the PIP process of the C/SiC composite material on the basis of ensuring the mechanical property of the composite material.

Description

A kind of preparation method of C/SiC composite material

Technical field

The invention belongs to the technical field of aerospace thermal structural material preparation, and specifically relates to a preparation method of C/SiC composite materials.

Background technique

Continuous fiber-toughened C/SiC ceramic matrix composites have become important candidate materials for aerospace hot-end components and hypersonic aircraft thermal protection systems due to their high temperature resistance, low density, and high strength. The theoretical long-term use temperature of carbon fiber can reach 2600°C, and the domestic carbon fiber industry is in full swing. It has gradually broken the technology monopoly and the cost has dropped rapidly. This is of great significance to the development and application of C/SiC composite materials in the field of aerospace thermal structural materials. .

Currently, the preparation of C/SiC ceramic matrix composites mainly uses the precursor impregnation pyrolysis process (PIP). Due to the limited impregnation efficiency of the precursor in the PIP process, and the escape of cracked products will cause problems such as high porosity, it requires repeated impregnation and cracking to achieve the densification of the C/SiC composite matrix. The above characteristics of the PIP process lead to a long cycle time when preparing C/SiC composite materials, which is not conducive to its engineering application in the preparation of advanced hot-end components.

In view of the shortcomings of the current long cycle time for preparing C/SiC composite materials using the PIP process, the present invention aims to provide a method for preparing C/SiC composite materials to effectively shorten the preparation cycle of the PIP process.

Contents of the invention

The object of the present invention is to provide a method for preparing a C/SiC composite material. The present invention also provides the prepared C/SiC composite material and its application.

In order to achieve the above objects, the present invention adopts the following technical solutions.

In a first aspect, the present invention provides a method for preparing C/SiC composite materials. The method includes the steps:

Using the C fiber preform as the reinforcing phase and the PCS/VHPCS multi-phase precursor slurry as the first impregnating agent, the first round of PIP cycle densification treatment is performed to prepare a composite intermediate;

Then, using the polymer silicon carbide precursor as the second impregnating agent, the prepared composite material intermediate is subjected to a second round of PIP cycle densification treatment to prepare a C/SiC composite material;

Wherein, the PCS/VHPCS composite phase precursor slurry is a slurry containing solid polycarbosilane (PCS), liquid vinyl perhydropolycarbosilane (VHPCS) and SiC nanopowder; and/or,

The polymer silicon carbide precursor is a solid polycarbosilane solution or a liquid vinyl perhydropolycarbosilane or a mixed solution of liquid vinyl perhydropolycarbosilane and solid polycarbosilane. The second impregnating agent does not contain SiC nanopowder.

As an embodiment of the present invention, the first round of PIP cycle densification treatment includes 3 PIP cycles; and/or, the second round of PIP cycle densification treatment includes 3 to 5 PIP cycles.

Among them, one PIP cycle refers to one PIP treatment operation, that is, one vacuum impregnation and one high-temperature cracking treatment. Specifically, vacuum impregnation is performed in the impregnating agent, and then placed in the cracking furnace to perform high-temperature cracking under an inert atmosphere. .

As a specific embodiment of the present invention, the preparation method of C/SiC composite material provided by the present invention includes:

First, the C fiber preform with the interface layer structure deposited on the surface is vacuum impregnated in the first impregnating agent, and then placed in a cracking furnace for high-temperature cracking in an inert atmosphere, thereby completing a PIP cycle; a PIP cycle is processed The final C fiber preform is vacuum impregnated in the first impregnating agent, and then placed in a cracking furnace for high-temperature cracking in an inert atmosphere, thus completing the second PIP cycle; and so on, a total of three PIP cycles are performed. , to prepare composite material intermediates;

After that, the composite material intermediate is vacuum impregnated in the second impregnating agent, and then placed in a cracking furnace for high-temperature cracking in an inert atmosphere, thereby completing a PIP cycle; the intermediate processed by a PIP cycle is then processed in a cracking furnace. Vacuum impregnation is carried out in the second impregnating agent, and then placed in a cracking furnace for high-temperature cracking under an inert atmosphere, that is, the second PIP cycle is completed; and so on, a total of 3 to 5 PIP cycles are performed to obtain the C/SiC composite Material.

As an embodiment of the present invention, in the first round of PIP cyclic densification treatment, the vacuum impregnation time is 15 to 30 hours, and the high temperature cracking treatment temperature is 800 to 1500°C; preferably, the first round of PIP In the cyclic densification treatment, the treatment temperature of high temperature cracking is 1100~1300℃.

As an embodiment of the present invention, in the second round of PIP cyclic densification treatment, the vacuum impregnation time is 15 to 30 hours, and the high temperature cracking treatment temperature is 800 to 1500°C; preferably, the second round of PIP In the cyclic densification treatment, the treatment temperature of high temperature cracking is 1100~1300℃.

As an embodiment of the present invention, in the PCS/VHPCS multi-phase precursor slurry, the mass ratio of solid polycarbosilane and liquid vinyl perhydropolycarbosilane is 1: (0.5-10), preferably 1: (1 to 5), more preferably 1:(3 to 5), more preferably 1:4.

As an embodiment of the present invention, in the PCS/VHPCS multi-phase precursor slurry, the mass of SiC nanopowder is 1 to 15% of the total mass of solid polycarbosilane and liquid vinyl perhydropolycarbosilane, preferably It is 5-12%, more preferably 9-11%, more preferably 10%.

As an embodiment of the present invention, a solvent is added to the PCS/VHPCS multi-phase precursor slurry, and the solvent is selected from any one or more of xylene, n-hexane, tetrahydrofuran, and butyl ether, preferably The solvent is xylene.

As an embodiment of the present invention, the amount of solvent in the PCS/VHPCS multi-phase precursor slurry is: the mass ratio of the solvent to the solid polycarbosilane is (0.1~10):1, preferably ( 0.25～9):1, more preferably (0.8～2):1, still more preferably (0.8～1.3):1, more preferably 1:1.

As an embodiment of the present invention, when the second impregnating agent is a solid polycarbosilane solution, the solid polycarbosilane solution is a xylene solution of solid polycarbosilane, and the mass percentage concentration is 45 to 55%.

As an embodiment of the present invention, when the second impregnating agent is a mixture of liquid vinyl perhydropolycarbosilane and solid polycarbosilane, the liquid vinyl perhydropolycarbosilane and solid polycarbosilane are in a mass ratio of ( 2～5):1 mixing, preferably mixing at a mass ratio (3～5):1.

As an embodiment of the present invention, the C fiber preform is selected from the group consisting of 2D, 2.5D, 3D, and needle punched C fiber preforms.

As an embodiment of the present invention, the surface of the C fiber preform is used as a reinforcing phase after depositing an interface layer structure; the interface layer is selected from the group consisting of pyrolytic carbon (PyC) interface layer, boron nitride (BN) interface layer, Any of pyrolytic carbon/SiC (PyC/SiC) multi-phase interface layer and boron nitride/SiC multi-phase interface layer (BN/SiC).

As a preferred embodiment of the present invention, when preparing the pyrolytic carbon (PyC) interface layer, a chemical vapor deposition process is used, the gas source is C ₃ H ₆ , and the deposition is performed at 800 to 1000°C and 0.5 to 4kPa for 2 to 60 hours. , C ₃ H ₆ flow rate is 200-800L/h, and argon gas flow rate is 200-800L/h.

As a preferred embodiment of the present invention, when preparing the boron nitride (BN) interface layer, a chemical vapor deposition process is used, the gas sources are boron trichloride and ammonia, hydrogen is used as the diluting gas, and the deposition temperature is 600 to 1100°C. , the deposition pressure is 500~2000Pa, the deposition time is 1~4h, the flow rate of boron trichloride is 0.4~1L/h, the flow rate of ammonia is 1.2~3L/h, and the flow rate of hydrogen is 4~8L/h.

As a preferred embodiment of the present invention, when preparing the SiC interface layer, a chemical vapor deposition process is used, using methyltrichlorosilane as the gas source, hydrogen as the carrier gas, the deposition temperature is 900~1200°C, and the pressure is 4~12kPa. The deposition time is 1 to 20 hours, and the flow molar ratio of methyltrichlorosilane and hydrogen is 1: (4 to 12).

In a second aspect, the present invention provides a C/SiC composite material obtained by the preparation method of the present invention.

In a third aspect, the present invention provides applications of the C/SiC composite materials obtained by the preparation method of the present invention, wherein the applications include applications as aerospace thermal structural materials.

The preparation method of C/SiC composite materials provided by the present invention aims at the shortcomings of the long PIP process cycle of the current C/SiC composite materials, and is prepared by using solid polycarbosilane (PCS) and liquid vinyl perhydropolycarbosilane (VHPCS). Multiphase silicon carbide precursor, and disperse an appropriate amount of SiC nanopowder in it to prepare PCS/VHPCS multiphase precursor slurry as the first matrix impregnating agent, and perform the first 3 steps of the carbon fiber preform (i.e., C fiber preform) PIP cycle, and then use the powder-free polymer silicon carbide precursor as the second matrix impregnating agent to perform the subsequent PIP cycle. On the basis of ensuring the mechanical properties of the composite material, the present invention can be used for more than 12 times. The preparation cycle of the PIP cycle is shortened to 6 to 8 PIP cycles, which significantly reduces the number of PIP cycles and effectively shortens the PIP process preparation cycle of C/SiC composite materials.

In addition, the present invention can not only make full use of the production capacity advantages of PCS and SiC nanopowders, but also fully utilize the advantages of VHPCS such as easy cross-linking and solidification and high ceramic yield, which is beneficial to the engineering application of the method of the present invention.

The beneficial effects of the present invention are as follows:

(1) The basic mechanical properties of the C/SiC composite material prepared by the present invention are excellent, not less than 80% of the performance of the C/SiC composite material prepared by the conventional PIP process.

(2) The present invention only requires 6 to 8 PIP cycles to prepare C/SiC composite materials. Compared with the current 12 to 15 PIP cycles that conventionally use PCS organic solution as the impregnating agent, the cycle is significantly shorter.

(3) The present invention can shorten the cost of preparing C/SiC composite materials. Since the cost of SiC nanopowder is lower than that of precursor-derived SiC, the introduction of some SiC nanopowder can further reduce the cost of preparing composite materials.

(4) The present invention can not only make full use of the production capacity advantages of PCS and SiC nanopowders, but also fully utilize the advantages of VHPCS such as easy cross-linking and solidification and high ceramic yield, which is beneficial to the engineering application of the method of the present invention.

Description of drawings

Figure 1 is a fracture SEM morphology of the C/SiC composite material prepared in Example 2 of the present invention;

Figure 2 is a comparison chart of the matrix weight gain curves of the C/SiC composite material prepared in Example 1 of the present invention and the C/SiC composite material prepared by conventional processes obtained in Experimental Example 1 of the effect of the present invention;

Figure 3 is a comparison chart of the normal temperature mechanical properties of the C/SiC composite materials prepared in Example 1 and Example 2 of the present invention and the C/SiC composite material prepared by conventional processes obtained in Experimental Example 2 of the effect of the present invention.

Detailed ways

The technical solution of the present invention is described in further detail below. Those skilled in the art should understand that the specific embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

It should be noted that, unless otherwise specified, the technical means used in the following examples are conventional means well known to those skilled in the art, and the raw materials used are all commercially available conventional commodities.

Example 1

This embodiment provides a C/SiC composite material. The preparation method includes the following steps:

(1) Cut 14 pieces of C fiber cloth with a size of 100mm×100mm and sew them together to prepare a C fiber preform with a two-dimensional structure (2D).

(2) Deposit and prepare a boron nitride (BN) interface layer on the surface of the C fiber preform, using a chemical vapor deposition process. The gas source is boron trichloride (BCl ₃ ) and ammonia. Hydrogen is used as the diluting gas. The deposition temperature is 900℃, deposition pressure is 800Pa, deposition time is 4h, boron trichloride flow rate is 0.8L/h, ammonia flow rate is 1.2L/h, and hydrogen flow rate is 6L/h.

(3) Perform the first round of PIP cycle densification treatment on the C fiber preform with boron nitride (BN) interface layer deposited on the surface, using PCS/VHPCS multi-phase precursor slurry as the first impregnating agent;

Among them, the first impregnating agent preparation method is: first prepare 400g of a xylene solution of solid polycarbosilane (PCS) with a concentration of 50wt%, and mix this solution with 800g of liquid vinyl perhydropolycarbosilane (VHPCS) and 100g of SiC nanopowder Mix the mixture thoroughly and mechanically stir evenly to obtain the first impregnating agent;

The C fiber preform with the boron nitride (BN) interface layer deposited on the surface is vacuum impregnated in the first impregnating agent (relative vacuum degree ≤ -0.8 bar) for 20 hours. After impregnation, it is placed in a cracking furnace and inert under nitrogen. Under the atmosphere, perform high-temperature cracking at 1250°C for 1 hour to complete a PIP cycle; then vacuum-impregnate the C fiber preform processed by one PIP cycle in the first impregnating agent for 20 hours, and then place it in the cracking furnace in nitrogen. Carry out high-temperature cracking at 1250°C for 1 hour under the atmosphere to complete the second PIP cycle; by analogy, a total of 3 PIP cycles are performed to obtain the composite material intermediate.

(4) Perform a second round of PIP cycle densification treatment on the composite intermediate prepared in step (3), use liquid vinyl perhydropolycarbosilane (VHPCS) as the second impregnating agent, and perform three PIP cycles. That is, the intermediate is vacuum impregnated in the second impregnating agent (relative vacuum degree ≤ -0.8 bar), the impregnation time is 20 hours, and after impregnation, it is placed in the cracking furnace, and high-temperature cracking is performed at 1250°C for 2 hours under a nitrogen inert atmosphere, completing once PIP cycle; the intermediate treated by the first PIP cycle is vacuum impregnated in the second impregnating agent for 20 hours, and then placed in the cracking furnace for high temperature cracking at 1250°C for 2 hours under a nitrogen atmosphere to complete the second PIP cycle; and so on, a total of 3 PIP cycles are performed to prepare the C/SiC composite material.

Example 2

This embodiment provides a C/SiC composite material. The preparation method includes the following steps:

(1) Cut 14 pieces of C fiber cloth with a size of 100mm×100mm and sew them together to prepare a C fiber preform with a two-dimensional structure (2D).

(2) Deposit and prepare the pyrolytic carbon (PyC) interface layer on the surface of the C fiber preform, using a chemical vapor deposition process, the gas source is C ₃ H ₆ , and deposited for 20 hours under the conditions of 980°C and 800Pa, C ₃ H ₆ flow rate It is 8L/min, and the argon flow rate is 8L/min.

(3) Perform the first round of PIP cycle densification treatment on the C fiber preform with the pyrolytic carbon (PyC) interface layer deposited on the surface, using PCS/VHPCS multi-phase precursor slurry as the first impregnating agent;

Among them, the first impregnating agent preparation method is: first prepare 400g of a xylene solution of solid polycarbosilane (PCS) with a concentration of 50wt%, and mix this solution with 800g of liquid vinyl perhydropolycarbosilane (VHPCS) and 100g of SiC nanopowder Mix the mixture thoroughly and mechanically stir evenly to obtain the first impregnating agent;

The C fiber preform with the pyrolytic carbon (PyC) interface layer deposited on the surface is vacuum impregnated in the first impregnating agent (relative vacuum degree ≤ -0.8 bar) for 25 hours. After impregnation, it is placed in a cracking furnace and placed in a nitrogen atmosphere. Perform high-temperature cracking at 1250°C for 0.5h under an inert atmosphere to complete a PIP cycle; then vacuum impregnate the C fiber preform in the first impregnating agent for 25h after one PIP cycle, and then place it in the cracking furnace. High-temperature cracking was carried out at 1250°C for 0.5h under a nitrogen atmosphere to complete the second PIP cycle; and by analogy, a total of 3 PIP cycles were performed to obtain the composite intermediate.

(4) Perform a second round of PIP cycle densification treatment on the intermediate prepared in step (3), use a solid polycarbosilane xylene solution with a concentration of 50wt% as the second impregnating agent, and perform 4 PIP cycles. The intermediate is vacuum impregnated in the second impregnating agent (relative vacuum degree ≤ -0.8 bar) for 20 hours. After impregnation, it is placed in a cracking furnace and subjected to high temperature cracking at 1250°C for 0.5 hours under a nitrogen inert atmosphere, completing once PIP cycle; the intermediate treated by the first PIP cycle is vacuum impregnated in the second impregnating agent for 20 hours, and then placed in the cracking furnace for high temperature cracking at 1250°C for 0.5 hours in a nitrogen atmosphere to complete the second PIP cycle; and so on, a total of 4 PIP cycles are performed to prepare the C/SiC composite material.

Example 3

This embodiment provides a C/SiC composite material. The preparation method includes the following steps:

(1) Cut 14 pieces of C fiber cloth with a size of 100mm×100mm and sew them together to prepare a C fiber preform with a two-dimensional structure (2D).

(2) Deposit and prepare a pyrolytic carbon (PyC) interface layer on the surface of the C fiber preform, using a chemical vapor deposition process, with the gas source being C ₃ H ₆ , and depositing for 40 hours at 980°C and 800 Pa, with a C ₃ H ₆ flow rate It is 8L/min, and the argon flow rate is 8L/min.

(3) Perform the first round of PIP cycle densification treatment on the C fiber preform with the pyrolytic carbon (PyC) interface layer deposited on the surface, using PCS/VHPCS multi-phase precursor slurry as the first impregnating agent;

Among them, the first impregnating agent preparation method is: first prepare 400g of a xylene solution of solid polycarbosilane (PCS) with a concentration of 50wt%, and mix this solution with 800g of liquid vinyl perhydropolycarbosilane (VHPCS) and 100g of SiC nanopowder Mix the mixture thoroughly and mechanically stir evenly to obtain the first impregnating agent;

The C fiber preform with the pyrolytic carbon (PyC) interface layer deposited on the surface is vacuum impregnated in the first impregnating agent (relative vacuum degree ≤ -0.8 bar) for 30 hours. After impregnation, it is placed in a cracking furnace and placed in a nitrogen atmosphere. Under an inert atmosphere, perform high-temperature cracking at 1250°C for 1 hour to complete a PIP cycle; then vacuum impregnate the C fiber preform in the first impregnating agent for 20 hours after one PIP cycle, and then place it in the cracking furnace. Carry out high-temperature cracking at 1250°C for 1 hour under nitrogen atmosphere to complete the second PIP cycle; and by analogy, perform a total of 3 PIP cycles to obtain the intermediate.

(4) The intermediate obtained in step (3) is subjected to a second round of PIP cycle densification treatment, using a mixture of liquid vinyl perhydropolycarbosilane and solid polycarbosilane (liquid vinyl perhydropolycarbosilane and solid Polycarbosilane (mixed with a mass ratio of 4:1) is used as the second impregnating agent, and three PIP cycles are performed, that is, the intermediate is vacuum impregnated in the second impregnating agent (vacuum degree ≤ -0.8bar), the impregnation time is 20 hours, after impregnation Place it in a cracking furnace and conduct high-temperature cracking at 1250°C for 1 hour under a nitrogen inert atmosphere to complete a PIP cycle; then vacuum impregnate the intermediate treated by a PIP cycle in a second impregnating agent for 20 hours, and then place it again Enter the cracking furnace and conduct high-temperature cracking at 1250°C for 1 hour in a nitrogen atmosphere to complete the second PIP cycle; and by analogy, a total of 3 PIP cycles are performed to prepare the C/SiC composite material.

The SEM morphology of the fracture surface of the C/SiC composite material prepared in Example 2 is shown in Figure 1. Obvious phenomena such as fiber pullout, debonding, and gradient peeling at the interface can be observed, reflecting the C prepared by this process. /SiC composite materials have good strengthening and toughening properties.

Effect Experiment Example 1

The matrix weight gain curves of the C/SiC composite material prepared in Example 1 of the present invention and the C/SiC composite material prepared by the conventional PIP process were compared. The comparison chart is shown in Figure 2.

It can be seen from Figure 2 that the weight gain effect of Example 1 after 6 PIP cycles can reach the matrix weight gain effect after 11 PIP cycles using the conventional process of PCS xylene solution.

Among them, the preparation method of the C/SiC composite material prepared using the conventional PIP process is different from the preparation method of Example 1 of the present invention in that: when the C fiber preform with a boron nitride (BN) interface layer deposited on the surface is subjected to PIP cycle densification treatment , a solid polycarbosilane xylene solution with a concentration of 50wt% was used as the impregnating agent, and a total of 11 PIP cycles were performed to prepare C/SiC composite materials.

Effect Experiment Example 2

The mechanical properties at room temperature were compared between the C/SiC composite materials prepared in Example 1 and Example 2 of the present invention and the C/SiC composite materials prepared using the conventional PIP process. The mechanical property test was conducted in accordance with the relevant standards of GBT 6569-2006.

The comparison of the normal temperature mechanical properties of the C/SiC composite materials prepared in Example 1 and Example 2 and the C/SiC composite material prepared by conventional processes is shown in Figure 3. It can be seen from Figure 3 that the bending strength of the C/SiC composite material prepared by the conventional process is 358.2MPa, while the room temperature bending strength of the C/SiC composite material prepared in Example 1 and Example 2 is 322.8MPa and 337.2MPa respectively. Achieved 90% and 94% of the former.

Among them, the preparation method of the C/SiC composite material prepared using the conventional PIP process is different from the preparation method of Example 1 of the present invention in that: when the C fiber preform with a boron nitride (BN) interface layer deposited on the surface is subjected to PIP cycle densification treatment , a solid polycarbosilane xylene solution with a concentration of 50wt% was used as the impregnating agent, and a total of 11 PIP cycles were performed to prepare C/SiC composite materials.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above. Those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. The embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily without conflict.

Claims (10)

1. A method for preparing a C/SiC composite material, the method comprising the steps of:

taking a C fiber preform as a reinforcing phase, and adopting PCS/VHPCS complex-phase precursor slurry as a first impregnant to perform a first round of PIP cyclic densification treatment to prepare an intermediate;

then, taking a polymer silicon carbide precursor as a second impregnant, and carrying out PIP cyclic densification treatment on the intermediate in a second round to prepare a C/SiC composite material;

the PCS/VHPCS complex-phase precursor slurry is slurry containing solid polycarbosilane, liquid vinyl perhydro polycarbosilane and SiC nano powder; and/or the number of the groups of groups,

the polymer silicon carbide precursor is solid polycarbosilane solution or liquid vinyl perhydro polycarbosilane and solid polycarbosilane mixed solution.

2. The method of manufacturing according to claim 1, wherein the first round of PIP cycle densification comprises 3 PIP cycles; and/or, the second round of PIP cycle densification comprises 3-5 PIP cycles.

3. The preparation method according to claim 1 or 2, wherein the mass ratio of solid polycarbosilane to liquid vinyl perhydro polycarbosilane in the PCS/VHPCS multiphase precursor slurry is 1 (0.5-10), preferably 1 (1-5), more preferably 1 (3-5); and/or the number of the groups of groups,

in the PCS/VHPCS multiphase precursor slurry, the mass of the SiC nano powder is 1-15% of the total mass of the solid polycarbosilane and the liquid vinyl perhydro polycarbosilane, preferably 5-12%, and more preferably 9-11%.

4. The preparation method according to claim 3, wherein a solvent is further added to the PCS/VHPCS complex phase precursor slurry, the solvent is selected from any one or more of xylene, n-hexane, tetrahydrofuran, and butyl ether, and preferably the solvent is xylene; and/or the number of the groups of groups,

the dosage of the solvent is as follows: the mass ratio of the solvent to the solid polycarbosilane is (0.1 to 10): 1, preferably (0.25 to 9): 1, more preferably (0.8 to 2): 1, and even more preferably (0.8 to 1.3): 1.

5. The method according to any one of claims 1 to 4, wherein when the second impregnating agent is a solid polycarbosilane solution, the solid polycarbosilane solution is a xylene solution of solid polycarbosilane, and the mass percentage concentration is 45 to 55%; and/or the number of the groups of groups,

when the second impregnant is a mixed liquid of liquid vinyl perhydro polycarbosilane and solid polycarbosilane, the liquid vinyl perhydro polycarbosilane and the solid polycarbosilane are mixed according to the mass ratio of (2-5): 1.

6. The method of any one of claims 1-5, wherein the C-fiber preform is selected from the group consisting of 2D, 2.5D, 3D, C-fiber preforms of needled knit construction.

7. The method of claim 6, wherein the surface of the C-fiber preform is deposited with an interfacial layer structure and then used as a reinforcing phase; the interface layer is selected from any one of pyrolytic carbon interface layer, boron nitride interface layer, pyrolytic carbon/SiC complex phase interface layer and boron nitride/SiC complex phase interface layer.

8. The method according to claim 1 or 2, wherein in the first round of PIP cyclic densification, the time of vacuum impregnation is 15 to 30 hours, and the treatment temperature of pyrolysis is 800 to 1500 ℃; and/or, in the second round of PIP circulating densification treatment, the time of vacuum impregnation is 15-30 hours, and the treatment temperature of pyrolysis is 800-1500 ℃.

9. A C/SiC composite material obtainable by the method of any one of claims 1 to 8.

10. Use of the C/SiC composite of claim 9 as an aerospace thermostructural material.