Self-healing modified compact C / SiC composite material and rapid densification method thereof

Abstract

The invention discloses a self-healing modified compact C / SiC composite material and a rapid densification method thereof, and relates to the technical field of material preparation, the method comprises the following steps: carrying out vacuum-pressure impregnation treatment on a semi-compact C / SiC composite material by using a precursor solution to obtain an impregnated material; carrying out curing treatment on the impregnated material to obtain a prefabricated body; carrying out high-temperature cracking treatment on the prefabricated body to obtain the self-healing modified semi-compact C / SiC composite material; and carrying out deposition treatment on the self-healing modified semi-compact C / SiC composite material to prepare the self-healing modified compact C / SiC composite material. According to the method, the semi-compact C / SiC composite material is subjected to single-time dipping treatment, so that a better compact effect can be achieved, the problem of low efficiency caused by multiple rounds of dipping is solved, deep penetration is realized through single-time vacuum-pressure dipping, self-healing components are introduced to be matched with curing and cracking treatment, pore regeneration is reduced, and the density of the composite material is improved. Residual holes of the material are further sealed through deposition treatment, and the preparation period is shortened while the density of the composite material is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material preparation, in particular to a self-healing modified dense C / SiC composite material and a rapid densification method thereof. BACKGROUND

[0002] C / SiC composite material has important application value in multiple industrial fields due to its excellent comprehensive performance. The material not only has the characteristics of light weight and high strength, but also shows good thermal stability and corrosion resistance, making it an ideal choice for high-temperature application scenarios such as hot end components of aero-engines and thermal protection systems of spacecraft.

[0003] Currently, there are two main densification processes for C / SiC composite materials in industrial production: (1) Chemical vapor deposition method, which passes gaseous precursors into a porous fiber preform, generates a ceramic matrix by pyrolysis or chemical reaction under the conditions of high temperature and low pressure, and deposits on the fiber surface. Although a high-purity matrix material can be obtained, there are significant shortcomings such as long process cycle, harsh equipment requirements, and inevitable presence of many pore defects in the final product; (2) Precursor impregnation and pyrolysis method, which impregnates an organic precursor solution into a fiber preform and then converts it into an inorganic ceramic matrix by pyrolysis. However, the porosity problem caused by matrix shrinkage and gas escape during multiple cycles of impregnation-pyrolysis is always difficult to effectively solve. Both of these two traditional methods have common problems such as complex process, high energy consumption, and low efficiency, which affect the densification and processing efficiency of C / SiC composite materials. SUMMARY

[0004] In order to overcome the shortcomings of the prior art, the present application provides a self-healing modified dense C / SiC composite material and a rapid densification method thereof, aiming to improve the densification and processing efficiency of C / SiC composite materials.

[0005] The first aspect of the present application provides a rapid densification method of a self-healing modified dense C / SiC composite material, comprising the following steps:

[0006] S1, performing vacuum-pressure impregnation treatment on a semi-dense C / SiC composite material using a precursor solution to obtain an impregnated material;

[0007] S2, performing curing treatment on the impregnated material to obtain a preform;

[0008] S3, performing high-temperature pyrolysis treatment on the preform to obtain a self-healing modified semi-dense C / SiC composite material;

[0009] S4, performing deposition treatment on the self-healing modified semi-dense C / SiC composite material to obtain a self-healing modified dense C / SiC composite material.

[0010] By the technical scheme, the semi-dense C / SiC composite material is subjected to vacuum pressure impregnation treatment, so that the air bubble barrier of the material can be eliminated and the precursor solution can be penetrated into the pores of the material to obtain a preform, and then the preform is subjected to solidification treatment, so that the preform forms a stable three-dimensional network structure to avoid deformation in subsequent high-temperature pyrolysis; in the pyrolysis process, the precursor is converted into a ceramic phase to reduce the pores of the material; the deposition treatment fills the pores on the surface of the body and seals the residual pores inside the material to improve the density; compared with the traditional process, the traditional process usually needs the precursor to be subjected to more than 9 times of repeated impregnation and pyrolysis, and the final process time is more than 200 hours, while the semi-dense C / SiC composite material is subjected to single impregnation treatment in the present application, so that good densification effect can be achieved, the problem of low efficiency caused by multiple impregnation is effectively solved, deep penetration is achieved through single vacuum-pressure impregnation, pores are reduced and regenerated through solidification and pyrolysis treatment, and residual pores of the modified semi-dense C / SiC composite material are further sealed and healed through deposition treatment, so that the density of the composite material is improved and the preparation period is shortened.

[0011] Compared with the existing pressure impregnation process, the existing pressure impregnation process adopts a gas pressurization method, in the traditional gas pressurization pressure impregnation process, the pressurized gas entering the pores of the semi-dense composite material will block the flow of the precursor into the material, and then leave closed pores in the material; in addition, the process also makes the precursor solution dissolve into the pressurized gas during the impregnation process, so that large-sized pores are generated in the ceramic converted from the precursor. The vacuum-pressure impregnation device designed in the present application adopts a method of mechanical pressurization on one side and vacuumization on the other side, which can effectively avoid the above problems of gas phase pressurization and significantly improve the densification effect of the material; the method can also improve the impregnation speed of the precursor by means of the pressure difference between the mechanical pressure and the vacuum, and the efficiency of preparing the C / SiC composite material can also be significantly improved since the present process does not need to use a solvent to dilute the precursor.

[0012] Optionally, the vacuum-pressure impregnation treatment specifically includes the following steps:

[0013] S11, placing the semi-dense C / SiC composite material in a vacuum-pressure impregnation device;

[0014] S12, adding the precursor solution into the vacuum-pressure impregnation device;

[0015] S13, performing vacuumization treatment on the vacuum-pressure impregnation device;

[0016] S14, applying a pressure of 1.0-4.0 MPa to the vacuum-pressure impregnation device for 3-15 min;

[0017] In the vacuumization treatment, the vacuum degree in the vacuum-pressure impregnation device is greater than -90 kPa.

[0018] Through the above technical solution, after the semi-dense C / SiC composite material and the precursor solution are placed in a vacuum-pressure impregnation device, the gas inside the device is removed to improve the permeability of the precursor solution. A vacuum degree greater than -90kPa can effectively reduce the penetration resistance of the precursor solution; then a constant pressure is applied to the impregnation device to prompt the precursor solution to fully fill the pores of the composite material. When the pressure is lower than 1.5MPa, the precursor solution is difficult to completely fill the pores. When the pressure is higher than 3.5MPa, the adsorption of the precursor solution and the composite material is affected. The pressure is maintained for 3-15 minutes to ensure that the solution fully fills the pores. The present invention first vacuums and exhausts the gas and then applies pressure to drive the precursor solution to penetrate. Combined with the optimization of vacuum control pressure and holding time, it can achieve more sufficient pore filling in a single treatment, shorten the preparation cycle, and reduce the occurrence of internal damage to the material caused by multiple impregnations.

[0019] Optionally, the vacuum-pressure impregnation device comprises:

[0020] The upper pressure part is provided with a pressurizing channel, through which the precursor solution enters the vacuum-pressure impregnation device;

[0021] a lower connecting portion, sealedly connected to the upper pressing portion, and used for containing a semi-dense C / SiC composite material;

[0022] a vacuum pump connected to the bottom of the lower connecting portion and used to extract gas from the vacuum-pressure impregnation device;

[0023] A pressure rod enters the upper pressure part through the pressure channel;

[0024] The hydraulic press presses the semi-dense C / SiC composite material in the lower connection part through a pressure rod.

[0025] Through the above technical solution, after the semi-dense C / SiC composite material is placed on the lower connection part, the upper pressure part is sealed and connected to the lower connection part, the precursor solution is injected into the closed cavity through the pressurized channel, and after the vacuum pump reduces the vacuum degree in the cavity to the target value, the hydraulic press drives the pressurizing rod to apply constant pressure to the impregnation solution; the split structure is convenient for clamping the material, and the independent pressurizing rod design can avoid the stress concentration caused by the overall pressurization. The synergistic effect of vacuum and pressure promotes the solution to fully penetrate the pores of the material; the present invention effectively removes the gas inside the composite material and realizes deep filling of the precursor solution by performing vacuum and pressurization simultaneously, thereby improving the efficiency of single impregnation, avoiding impregnation cycles and improving the processing efficiency of the composite material.

[0026] Optionally, the precursor solution is a polymer organosilicon precursor or a mixture of a polymer organosilicon precursor and an organic solvent;

[0027] The precursor solution is PSNB, but is not limited to PSNB precursor;

[0028] The mass ratio of the organic solvent to the polymer organosilicon precursor is 0-1:1.

[0029] Through the above technical solution, the organic solvent can dilute the precursor solution and maintain the fluidity of the precursor solution. The present invention adjusts the viscosity of the precursor solution so that the precursor solution can effectively penetrate into the different pore structures in the semi-dense C / SiC composite material, thereby reducing the hole defects formed by insufficient local penetration.

[0030] Optionally, the curing temperature of the curing treatment is 50-250° C., and the holding time of the curing treatment is 1-3 hours.

[0031] Through the above technical solution, curing treatment is carried out at 50-250°C to ensure that the precursor solution is fully cross-linked and cured without thermal decomposition, thereby avoiding excessive temperature causing the precursor solution to volatilize too quickly to form pores; 1-3h of heat preservation can not only ensure that the precursor completes the cross-linking reaction to form a stable preform structure, providing a stable skeleton support for subsequent high-temperature cracking treatment, but also prevent resource waste or excessive oxidation caused by too long a time; the present invention realizes the efficient conversion of the precursor solution into the preform, ensures that the cured product has a stable chemical structure and mechanical properties, and lays the foundation for the densification of the ceramic matrix in the subsequent cracking process. At the same time, the optimized curing parameters shorten the process cycle while ensuring material properties, avoiding energy waste.

[0032] Optionally, the temperature of the high-temperature pyrolysis treatment is 800-1200°C, the heating rate of the high-temperature pyrolysis is 0-6°C / min, and the cooling rate is 0-6°C / min;

[0033] The holding time of the high temperature cracking is 1-3 hours.

[0034] Through the above technical solution, pyrolysis is carried out at a temperature of 800-1200°C, and the pyrolysis reaction is completed at this temperature for 1-3 hours. The heating rate matches the thermal expansion coefficient of the material to avoid matrix cracking due to excessive temperature difference. The slow cooling process can effectively release the residual stress inside the material. Combined with sufficient insulation time, the pyrolysis products form a self-healing modified semi-dense C / SiC composite material.

[0035] Optionally, the curing treatment and the high-temperature cracking treatment are both carried out under a protective gas atmosphere.

[0036] Optionally, the deposition process comprises the following steps:

[0037] Step 1: placing the self-healing modified semi-dense C / SiC composite material in a chemical vapor infiltration furnace;

[0038] Step 2: Mix the precursor with hydrogen and argon and introduce them into a chemical vapor infiltration furnace to deposit the self-healing modified semi-dense C / SiC composite material.

[0039] Through the above technical solution, the self-healing modified semi-dense C / SiC composite material obtained after high-temperature cracking forms a porous structure, the precursor is transported by a mixed gas in a chemical vapor infiltration furnace, argon is used as a carrier to evenly disperse the precursor molecules, hydrogen is used as a reducing agent to lower the cracking temperature and inhibit the generation of free carbon, and the generated silicon carbide gradually fills the pores. During the deposition process, the reaction gas concentration gradient is maintained by continuously introducing the mixed gas, which promotes the uniform growth of the deposited layer along the depth direction of the pores; the present invention uses the synergistic effect of hydrogen and argon mixed gases to maintain the precursor delivery efficiency while optimizing the cracking reaction path, so that the deposited material preferentially nucleates and grows inside the pores, shortening the single deposition time, effectively reducing the number of depositions, avoiding interface damage caused by multiple depositions, and at the same time inhibiting the formation of closed pores and improving the density of the material.

[0040] Optionally, the pressure in the chemical vapor infiltration furnace is 5 kPa, the temperature of the deposition reaction is the same as that of the high-temperature pyrolysis reaction, and the deposition time is 60 h;

[0041] The flow ratio of the precursor, hydrogen and argon is 1:1:(1-3).

[0042] Through the above technical scheme, the self-healing modified semi-dense C / SiC composite material obtained after high-temperature pyrolysis is directly transferred to a chemical atmospheric infiltration furnace. The pressure in the furnace is stabilized at 5kPa by vacuuming and mixed gas injection, which is conducive to the diffusion of the mixed gas, reduces premature surface closure, and improves the infiltration uniformity inside the material. Too low pressure will affect the deposition rate. The deposition temperature is consistent with the high-temperature pyrolysis temperature to reduce interface damage caused by thermal fluctuations. Too high temperature leads to too fast deposition, and the pores of the self-healing modified semi-dense C / SiC composite material are closed. Too low temperature can easily cause incomplete deposition reaction. The self-healing modified semi-dense C / SiC composite material does not require secondary heating, which reduces thermal stress. While ensuring effective penetration of the precursor, the single deposition cycle is shortened, reducing process energy consumption. Argon is used as a carrier to dilute the precursor concentration, and hydrogen promotes precursor pyrolysis and inhibits carbon deposition.

[0043] A second aspect of the present invention provides a self-healing modified dense C / SiC composite material, which is prepared according to any of the above-mentioned preparation methods. The porosity reduction rate of the self-healing modified dense C / SiC composite material is greater than 20%.

[0044] By the technical scheme, the self-healing modified dense C / SiC composite material is prepared by single vacuum-pressure impregnation combined with PIP and CVI method, the problems of low efficiency and pore regeneration caused by multiple cycles in the traditional method are avoided, the porosity in the material is effectively reduced, and the densification efficiency of the C / SiC composite material is improved.

[0045] The application has the advantages that: the self-healing modified dense C / SiC composite material is prepared by vacuum-pressure impregnation combined with PIP and CVI method, the production cycle is significantly shortened under the premise of ensuring the material performance, the precursor solution is fully infiltrated by optimizing the impregnation device and process parameters, the porosity of the material is effectively reduced, and the process cycle is short, the densification is high, and the porosity is low. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 It is a flowchart of a rapid densification method of a self-healing modified dense C / SiC composite material provided by the embodiment of the application.

[0047] Figure 2 It is a structural schematic diagram of a vacuum-pressure impregnation device and an anti-backflow device.

[0048] Figure 3 It is a mu CT graph of example 1.

[0049] Figure 4 It is a mu CT graph of example 2.

[0050] Figure 5 It is a mu CT graph of example 3.

[0051] Figure 6 It is a mu CT graph of example 1.

[0052] Figure 7 It is a mu CT graph of a material without densification treatment.

[0053] In the figure: 1, upper pressing part; 11, pressing rod; 2, lower joint part; 21, joint; 22, locking bolt; 3, vacuum pump; 4, sample table; 5, rubber ring; 6, sealing ring; 7, pipeline; 8, conical flask; 91, first valve; 92, second valve. DETAILED DESCRIPTION

[0054] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0055] Figure 1Flowchart of a rapid densification method of a self-healing modified dense C / SiC composite material provided by an embodiment of the present invention, such as Figure 1 As shown, the method includes the following steps:

[0056] S1. vacuum-pressure impregnation treatment is performed on a semi-dense C / SiC composite material using a precursor solution to obtain an impregnated material;

[0057] S2, curing the impregnated material to obtain a preform;

[0058] S3, performing high-temperature cracking treatment on the preform to obtain a self-healing modified semi-dense C / SiC composite material;

[0059] S4. Performing a deposition treatment on the self-healing modified semi-dense C / SiC composite material to obtain a self-healing modified dense C / SiC composite material.

[0060] The raw material information involved in the present invention is shown in Table 1.

[0061] Table 1 Raw material information

[0062] raw material source PSNB precursor Beijing Institute of Chemistry, Chinese Academy of Sciences Tetrahydrofuran Tianjin Fuyu Fine Chemical Co., Ltd. Argon Xi'an Weiguang Gas Co., Ltd. Deionized water Xi'an Xinyuan Distilled Water Plant

[0063] The semi-dense C / SiC composite material of the present invention is woven from ceramic fiber bundles or carbon fiber bundles in two-dimensional plain weave, two-dimensional satin weave, 2.5D weave, three-dimensional four-way weave, and three-dimensional needle weave. The 2.5D weaving C / SiC composite material used in the embodiments and comparative examples of the present invention has an initial average open porosity of 21.3±1% and an average bulk density of 1.8±0.04 g / cm 3 .

[0064] The semi-dense C / SiC composite material needs to be pretreated before vacuum-pressure impregnation treatment. The specific steps are as follows:

[0065] After using deionized water to clean impurities and dust on the surface of the semi-dense C / SiC composite material, place it in a beaker filled with deionized water, and then place the beaker in a CR-040S ultrasonic cleaning machine for cleaning for 5-10 minutes;

[0066] The cleaned semi-dense C / SiC composite material is placed in a BPG-7032 vacuum drying oven and dried at 40-70° C. for 8-24 hours to obtain a pretreated semi-dense C / SiC composite material.

[0067] Reference Figure 2The vacuum-pressure impregnation device comprises an upper pressing part 1, a lower connecting part 2, a vacuum pump 3, a pressurizing rod 11 and an INSTRON 8801 universal testing machine. The upper pressing part 1 is provided with a pressurizing channel in the axial direction. The lower connecting part 2 is fixedly connected with a sample table 4. The sample table 4 is provided with a plurality of air holes. The semi-dense C / SiC composite material is placed on the sample table 4. The upper pressing part 1 and the lower connecting part 2 are provided with rubber ring grooves for placing rubber rings 5 on the two sides close to each other. The upper pressing part 1 is sealingly connected with the lower connecting part 2 through locking bolts 22. The precursor solution enters the vacuum-pressure impregnation device from the pressurizing channel. The pressurizing channel is provided with a sealing groove for placing a sealing ring 6. The pressurizing rod 11 is inserted into the upper pressing part 1 along the pressurizing channel.

[0068] The vacuum pump 3 is communicated with the bottom of the lower connecting part 2 through a joint 21. In order to prevent the precursor solution from being sucked into the vacuum pump 3 through the joint 21, the joint 21 is inserted into the outer periphery of the lower connecting part 2 in the horizontal direction and is sealingly communicated with the lower connecting part 2. An anti-back suction device is arranged between the joint 21 and the vacuum pump 3. The anti-back suction device comprises two pipes 7 which are respectively communicated with the vacuum pump 3 and the lower connecting part 2. The other ends of the two pipes 7 are inserted into a conical flask 8. The two pipes 7 are respectively provided with two-way valves for controlling the gas flow rate. The one close to the vacuum pump 3 is a first valve 91 and the one close to the vacuum-pressure impregnation device is a second valve 92. The conical flask 8 contains liquid. The pipe openings of the two pipes 7 are arranged above the liquid level. In the initial state, the first vacuum pump 3 is opened and the second vacuum pump 3 is closed.

[0069] When the semi-dense C / SiC composite material needs to be subjected to vacuum-pressure impregnation treatment, firstly, the sample table 4 is placed on the lower connecting part 2 and the semi-dense C / SiC composite material is placed on the sample table 4. Then, the rubber ring 5 is placed in the rubber ring groove. The upper pressing part 1 and the lower connecting part 2 are locked through the plurality of locking bolts 22. The pressurizing rod 11 is inserted into the upper pressing part 1 along the pressurizing channel. Then, the vacuum pump 3, the anti-back suction device and the lower connecting part 2 are sequentially communicated. After the vacuum pump 3 is opened and air is sucked for 5-20 s, the first valve 91 is closed and the second valve 92 is opened. The gas in the vacuum-pressure impregnation device is completely sucked out. The vacuum degree in the vacuum-pressure impregnation device is greater than -90 kPa. Finally, the hydraulic machine is used to apply a pressure of 1.0-4.0 MPa to the top end of the pressurizing rod 11. The bottom end of the pressurizing rod 11 presses the semi-dense C / SiC composite material. The pressure is maintained for 3-15 min. The impregnated material is prepared.

[0070] The preparation method of the C / SiC composite material related to the present application will be specifically described in combination with specific examples and comparative examples.

[0071] Example

[0072] Example 1

[0073] A method for rapidly densifying a self-healing modified dense C / SiC composite material comprises the following steps:

[0074] S1. Add 10 ml of PSNB (polysilazane borane) precursor to a 50 ml beaker, then slowly add 10 ml of tetrahydrofuran to the beaker and continue stirring to mix evenly to obtain a precursor solution. The precursor solution is used to perform vacuum-pressure impregnation treatment on a 2.5D woven C / SiC composite material. The hydraulic press pressure is 1.6 MPa and the pressure is maintained for 5 minutes to obtain an impregnated material.

[0075] S2. The impregnated material was placed in a GSL-1100W tube furnace, and the temperature in the tube furnace was raised to 170°C at a heating rate of 4°C / min and kept at this temperature for 1 hour. The temperature in the tube furnace was then lowered to room temperature at a cooling rate of 2°C / min to obtain a preform. Argon gas was introduced into the tube furnace throughout the curing process.

[0076] S3. Grinding off the remaining precursor on the surface of the preform with a file, placing the polished preform in a tube furnace, then heating the temperature in the tube furnace to 1000° C. at a heating rate of 4° C. / min and keeping it at that temperature for 2 h, then cooling the temperature in the tube furnace to room temperature at a cooling rate of 2° C. / min, and introducing argon gas into the tube furnace throughout the process to obtain a self-healing modified semi-dense C / SiC composite material;

[0077] S4. Place the self-healing modified semi-dense C / SiC composite material in a chemical vapor infiltration furnace, and introduce trichloromethylsilane, hydrogen and argon into the reaction chamber of the chemical vapor infiltration furnace by bubbling at a flow ratio of 1:1:1. The pressure in the reaction chamber is 5 kPa, the temperature is 800°C, and the deposition time is 60 h to obtain a dense C / SiC composite material.

[0078] Example 2

[0079] A method for rapid densification of a self-healing modified dense C / SiC composite material is different from Example 1 in that the pressure applied by the hydraulic press is 3.2 MPa.

[0080] Example 3

[0081] A method for rapid densification of a self-healing modified dense C / SiC composite material is different from Example 1 in that the pressure of the hydraulic press is 3.2 MPa and the holding time is 10 minutes.

[0082] Comparative Example

[0083] Comparative Example 1

[0084] A rapid densification method of self-healing modified dense C / SiC composite material, different from example 1 is that the treatment method of the impregnation material is different, the precursor solution is used to perform vacuum impregnation treatment on the 2.5D woven C / SiC composite material, and the impregnation is performed in a vacuum impregnation tank, a beaker containing PSNB precursor solution is placed in the vacuum impregnation tank, the sample is hung on the iron wire passing through the top cover of the impregnation tank, and the sample is not in contact with the precursor solution when the sample is hung. Connect the air path, start the vacuum pump, and time after the vacuum degree is stable, push the iron wire down after 30 minutes, and immerse the sample completely in the precursor solution. After impregnation for 30 minutes, close the vacuum pump, and slowly open the impregnation pipe valve until the air pressure inside and outside the impregnation tank is balanced.

[0085] Comparative example 2

[0086] A rapid densification method of self-healing modified dense C / SiC composite material, different from example 1 is that the self-healing modified semi-dense C / SiC composite material is not subjected to deposition treatment, that is, only vacuum-pressure impregnation PIP process is performed, and CVI process is not performed.

[0087] Comparative example 3

[0088] A rapid densification method of self-healing modified dense C / SiC composite material, different from comparative example 1 is that the self-healing modified semi-dense C / SiC composite material is not subjected to deposition treatment, that is, only vacuum-pressure impregnation PIP process is performed, and CVI process is not performed.

[0089] Comparative example 4

[0090] A rapid densification method of self-healing modified dense C / SiC composite material, different from example 1 is that the treatment method of the impregnation material is different, now the vacuum impregnation PIOP method is used, the C / SiC preform is vacuum impregnated with a precursor and is solidified, and then is directly placed into a CVI deposition furnace, and on-line cracking is performed in the heating process of the deposition furnace.

[0091] The preparation method of the self-healing modified dense C / SiC composite material of example 2-3 and comparative examples 1-4 is the same as that of example 1.

[0092] Performance detection

[0093] The dense C / SiC composite material provided by examples 1-3 and comparative examples 1-4 of the application is subjected to the following performance detection, and table 2 is the performance detection result.

[0094] Density: Take a 20 mm diameter circular blank sample, the dense C / SiC composite material samples of Examples 1-3 and Comparative Examples 1-4, and weigh them as m1. Immerse the sample in water for more than 30 minutes. Take out the saturated sample and wipe off the surface droplets, then weigh it as m2. Hang the saturated sample in water and weigh it as m3. The density is calculated as follows:

[0095]

[0096] Density change rate: Take 5 samples of the blank group with a diameter of 20 mm, 5 samples from Examples 1-3 and Comparative Examples 1-4, and measure 5 density values. Calculate the average density of the 5 blank groups and the average density of the 5 density values ​​of Examples 1-3 and Comparative Examples 1-4. Calculate the density change rate using the following formula:

[0097]

[0098] Porosity: Take m1, m2 and m3 of each sample of the blank group, Examples 1-3 and Comparative Examples 1-4 in the density measurement respectively, and calculate the porosity of the densified C / SiC composite material sample by the following formula:

[0099]

[0100] Porosity reduction rate: Take 5 samples of the blank group, Examples 1-3, and Comparative Examples 1-4, each with a diameter of 20 mm, and measure 5 porosity values. Calculate the average porosity of the 5 blank groups and the average porosity of the 5 samples of Examples 1-3 and Comparative Examples 1-4. Calculate the porosity reduction rate using the following formula:

[0101]

[0102] Three samples were taken for each embodiment and comparative example, and the average value of the density and porosity test results was taken. The specific test results are shown in Table 2.

[0103] Table 2 Performance results

[0104]

[0105] The present invention replaces the traditional vacuum impregnation process and pressure impregnation process by combining a single vacuum-pressure impregnation process and a vacuum-pressure impregnation device to achieve deep penetration, reduce pore regeneration with optimized curing and cracking parameters, and finally further seal the residual pores through the deposition process. Figure 2-7 As shown in the figure, the material density and porosity are improved while the preparation cycle is shortened to within 100 hours, while the traditional pressure impregnation needs to be repeated more than 9 times to achieve the densification effect of the present invention.

[0106] Finally, it should be noted that the above descriptions are merely optional examples of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for rapid densification of a self-healing modified dense C / SiC composite material, characterized in that: The steps include: S1. vacuum-pressure impregnation treatment is performed on a semi-dense C / SiC composite material using a precursor solution to obtain an impregnated material; S2, curing the impregnated material to obtain a preform; S3, performing high-temperature cracking treatment on the preform to obtain a self-healing modified semi-dense C / SiC composite material; S4. Performing a deposition treatment on the self-healing modified semi-dense C / SiC composite material to obtain a self-healing modified dense C / SiC composite material.

2. The method for rapid densification of a self-healing modified dense C / SiC composite material according to claim 1, characterized in that: The vacuum-pressure impregnation process specifically comprises the following steps: S11, placing the semi-dense C / SiC composite material on the lower connecting portion, and sealingly connecting the upper connecting portion and the lower connecting portion; S12, adding the precursor solution into a vacuum-pressure impregnation device through a pressurized channel; S13, vacuuming the vacuum-pressure impregnation device by using the vacuum pump; S14, applying a pressure of 1.0-4.0 MPa to the vacuum-pressure impregnation device and maintaining the pressure for 3-15 minutes; Wherein, the vacuum degree in the vacuum-pressure impregnation device during the vacuum treatment is greater than -90 kPa.

3. The method for rapid densification of a self-healing modified dense C / SiC composite material according to claim 2, characterized in that: The vacuum-pressure impregnation device comprises: The upper pressure part is provided with a pressurizing channel, through which the precursor solution enters the vacuum-pressure impregnation device; a lower connecting portion, sealedly connected to the upper pressing portion, and used for containing a semi-dense C / SiC composite material; a vacuum pump connected to the bottom of the lower connecting portion and used to extract gas from the vacuum-pressure impregnation device; A pressure rod enters the upper pressure part through the pressure channel; The hydraulic press presses the semi-dense C / SiC composite material in the lower connection part through a pressure rod.

4. The method for rapid densification of a self-healing modified dense C / SiC composite material according to claim 1, characterized in that: The precursor solution is a polymer organosilicon precursor or a mixture of a polymer organosilicon precursor and an organic solvent; The precursor solution is PSNB, but is not limited to PSNB precursor; The mass ratio of the organic solvent to the polymer organosilicon precursor is 0-1:

1.

5. The method for rapid densification of a self-healing modified dense C / SiC composite material according to claim 1, characterized in that: The curing temperature of the curing treatment is 50-250° C., and the heat preservation time of the curing treatment is 1-3 hours.

6. The method for rapid densification of a self-healing modified dense C / SiC composite material according to claim 1, characterized in that: The temperature of the high temperature pyrolysis treatment is 800-1200°C, the heating rate of the high temperature pyrolysis is 0-6°C / min, and the cooling rate is 0-6°C / min; The holding time of the high temperature cracking is 1-3 hours.

7. The method for rapid densification of a self-healing modified dense C / SiC composite material according to claim 1, characterized in that: The curing treatment and high-temperature cracking treatment are both carried out under a protective gas atmosphere.

8. The method for rapid densification of a self-healing modified dense C / SiC composite material according to claim 1, wherein the deposition process comprises the following steps: Step 1: placing the self-healing modified semi-dense C / SiC composite material in a chemical vapor infiltration furnace; Step 2: Mix the precursor with hydrogen and argon and introduce them into a chemical vapor infiltration furnace to deposit the self-healing modified semi-dense C / SiC composite material.

9. The method for rapid densification of a self-healing modified dense C / SiC composite material according to claim 8, characterized in that: The pressure in the chemical vapor infiltration furnace is 5 kPa, the temperature of the deposition reaction is the same as that of the high-temperature pyrolysis reaction, and the deposition time is 60 h; The flow ratio of the precursor, hydrogen and argon is 1:1:(1-3).

10. A self-healing modified dense C / SiC composite material, prepared according to the preparation method according to any one of claims 1 to 9, characterized in that: The porosity reduction rate of the self-healing modified dense C / SiC composite material is greater than 20%.

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