Preparation method of high-temperature-resistant, radiation-resistant and stealth multi-functional integrated ceramic matrix composite material

Abstract

The application relates to a preparation method of a high-temperature-resistant, radiation-resistant and stealth multifunctional integrated ceramic matrix composite material, which comprises the following steps: a. ball milling to prepare coated slurry containing functional filling particles and chemical vapor infiltration (CVI) process to prepare a silicon carbide (SiC) preform cloth; b. uniformly coating the mixed slurry on the surface of the SiC preform cloth and stacking and fixing the SiC preform cloth; and c. performing the CVI process on the fixed preform to deposit a silicon nitride (Si3N4) matrix to densify. The preparation method provided by the application realizes the high-temperature-resistant, radiation-resistant and stealth multifunctional structure integration of the ceramic matrix composite material, strengthens the mechanical properties of the ceramic matrix radiation shielding material in a high-temperature environment, improves the multifunctionality and high-temperature environment durability of the ceramic matrix composite material, and expands the application range of the ceramic matrix composite material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of radiation shielding materials, and relates to a preparation method of a high-temperature-resistant, anti-radiation and stealth multifunctional integrated ceramic matrix composite material. BACKGROUND

[0002] With the development of aerospace, nuclear weapons, energy and the like and the increase in the application of portable radiation sources, the requirements for radiation shielding materials are continuously improved. The existing shielding materials are difficult to realize the compatibility of shielding performance and mechanical properties and high-temperature resistance, and have low integration degree of function and structure, and thus cannot meet the use requirements. The ceramic matrix composite material has high specific strength, excellent high-temperature resistance and strong designability, and has been widely applied in the fields of aviation, aerospace, nuclear energy and the like, and is an optimal material for realizing the integration of function and structure.

[0003] At present, compared with metal-based shielding materials, polymer-based shielding materials, concrete and glass shielding materials, the research and application of ceramic-based shielding materials are relatively less in the field of radiation shielding and protection. The complex application environment has higher and higher requirements for the performance of the radiation shielding material. The material not only has excellent shielding performance, but also has good mechanical properties, high-temperature resistance and anti-radiation performance. Many existing shielding materials are difficult to meet the use requirements, mainly in that the shielding performance of the material is difficult to be compatible with other properties such as mechanical properties. Improving the integration degree of structure / function of the shielding material is an important research direction in the field at present and in the future. Therefore, in addition to optimizing the traditional radiation shielding, developing new and composite radiation shielding materials has great theoretical significance and application prospect. SUMMARY

[0004] Technical problems to be solved

[0005] In order to avoid the shortcomings of the prior art, the application provides a preparation method of a high-temperature-resistant, anti-radiation and stealth multifunctional integrated ceramic matrix composite material, which solves the problems of weak comprehensive performance of the radiation shielding material in a complex and harsh service environment and poor high-temperature mechanical properties. The high-temperature-resistant, anti-radiation and stealth multifunctional integrated ceramic matrix composite material is prepared by the CVI process and the coating and layering method, the performance stability of the ceramic-based radiation shielding material in a thermal environment and a radiation environment is enhanced, the mechanical properties of the ceramic-based radiation shielding material in a high-temperature environment are improved, the multifunctionality and high-temperature environmental durability of the ceramic matrix composite material are improved, and the application range of the ceramic matrix composite material is expanded.

[0006] Technical scheme

[0007] A preparation method of a high-temperature-resistant, anti-radiation and stealth multifunctional integrated ceramic matrix composite material, characterized by the following steps:

[0008] Step 1: depositing boron nitride BN interface and silicon nitride Si3N4 protective layer on multiple SiC fiber cloths in sequence by using CVI process;

[0009] When depositing the boron nitride BN interface, the precursor gas source is boron trichloride BCl3 and ammonia NH3, wherein BCl3 is a boron source, NH3 is a nitrogen source, the carrier gas is argon Ar, and the dilution gas is hydrogen H2;

[0010] When depositing the silicon nitride Si3N4 protective layer, the precursor gas source is silicon tetrachloride SiCl4 and ammonia NH3, wherein SiCl4 is a silicon source, NH3 is a nitrogen source, the carrier gas is argon Ar, and the dilution gas is hydrogen H2;

[0011] Step 2: applying mixed coating slurry to the surface of each SiC preform cloth deposited in step 1, and then fixing the multiple SiC preform cloths in a stack;

[0012] The mixed coating slurry is a mixture of 50-60% by volume of W powder, 20-30% of B4C powder and 10-20% of Sm2O3 powder, and ultrapure water, and then adding polycarbosilane PCS;

[0013] The additional polycarbosilane PCS is 50-60wt%;

[0014] Step 3: depositing Si3N4 matrix by using CVI process to densify the SiC preform cloth, and obtaining high-temperature-resistant, radiation-resistant and stealth multi-functional integrated ceramic matrix composite material;

[0015] When depositing the Si3N4 matrix by using the CVI process, the precursor gas source is silicon tetrachloride SiCl4 and ammonia NH3, wherein SiCl4 is a silicon source, NH3 is a nitrogen source, the carrier gas is argon Ar, and the dilution gas is hydrogen H2.

[0016] The SiC preform cloth is a two-dimensional woven structure of SiC fiber cloth.

[0017] The multiple SiC fiber cloths are 8-10.

[0018] The deposition time of the boron nitride BN interface is 160-260h, and the deposition temperature is 650-850℃; the gas flow ratio is: boron source BCl3 is 20-30ml / min, nitrogen source NH3 is 60-70ml / min, carrier gas argon Ar is 100-120ml / min, and dilution gas hydrogen H2 is 100-120ml / min.

[0019] The deposition time of the deposited silicon nitride Si3N4 protective layer is 120-220 h, and the deposition temperature is 800-1000℃; the gas flow ratio is: silicon source SiCl4 is 100-110 ml / min, nitrogen source NH3 is 60-70 ml / min, carrier gas argon Ar is 100-120 ml / min, and dilution gas hydrogen H2 is 100-120 ml / min.

[0020] The deposition temperature of the CVI process of step 3 is 800-1000℃; the gas flow ratio is: silicon source SiCl4 is 100-110 ml / min, nitrogen source NH3 is 60-70 ml / min, carrier gas argon Ar is 100-120 ml / min, and dilution gas hydrogen H2 is 100-120 ml / min.

[0021] The mixed powder of the W powder, B4C powder and Sm2O3 powder is prepared by a ball milling process, the ball-to-material ratio is 7:1-9:1, and the ball milling time is 24 h to prepare the mixed powder.

[0022] The ratio of the mixed powder to ultrapure water in the mixed coating slurry is 4:1-6:1 by mass.

[0023] A high-temperature-resistant, radiation-resistant and stealth multifunctional integrated ceramic matrix composite material prepared by the preparation method, characterized in that: the structure of the multifunctional integrated ceramic matrix composite material is SiC f / Si3N4-W-B4C-Sm2O3-SiC, including SiC fiber cloth, and the SiC fiber cloth is provided with a boron nitride BN interface with a thickness of 450-500 nm; the BN interface is provided with silicon nitride Si3N4 with a thickness of 2.5-4.5 μm; the SiC fiber cloth is provided with WBS functional group particles and polycarbosilane PCS functional group particles to form WBSP (W-B4C-Sm2O3-PCS) functional filling material; the overall structure is densified by a CVI process; the SiC f / Si3N4-WBSP composite material has a densification degree of not less than 85%; the SiC f / Si3N4-WBSP composite material has a linear attenuation coefficient and a mass attenuation coefficient of 0.242 cm -1 and 0.103 cm 2 / g, respectively; the shielding effect reaches more than 70%; the RL value can reach a full-frequency absorption of-9 dB or less, the electromagnetic wave absorption rate is about 87% or more, and the effective wave absorption bandwidth is 3.52 GHz.

[0024] An application of the aforementioned high-temperature resistant, radiation-resistant, and stealth-functional integrated ceramic matrix composite material is characterized by its suitability for use in complex high-temperature radiation environments with temperatures up to 1350℃, radiation source energy of 0.662 MeV, and electromagnetic wave frequency of 12.4 GHz; while maintaining good shielding and stealth performance, wherein the shielding effect and electromagnetic wave absorption rate can reach over 70% and 87% respectively at room temperature; and at an ambient temperature of 1350℃, SiC... f The shielding effect and electromagnetic wave absorption rate of the / Si3N4-WBSP composite material are reduced, reaching 54% and 85% or more, respectively.

[0025] Beneficial effects

[0026] This invention proposes a method for preparing a high-temperature resistant, radiation-resistant, and stealth-functional integrated ceramic matrix composite material, comprising the following steps: a. preparing a coating slurry containing functional filler particles by ball milling and preparing a silicon carbide (SiC) prefabricated fabric by chemical vapor infiltration (CVI); b. uniformly coating the mixed slurry onto the surface of the SiC prefabricated fabric and stacking and fixing it neatly; c. densifying the stacked and fixed prefabricated body by depositing a silicon nitride (Si3N4) matrix using a CVI process. The preparation method provided by this invention achieves a high-temperature resistant, radiation-resistant, and stealth-functional integrated structure of the ceramic matrix composite material, enhances the mechanical properties of ceramic matrix radiation shielding materials in high-temperature environments, improves the multifunctionality and high-temperature durability of the ceramic matrix composite material, and expands the application range of the ceramic matrix composite material.

[0027] Regarding densification, the material of this invention, SiC f The densification degree of the Si3N4-WBSP composite material is not less than 85%;

[0028] In terms of radiation resistance, SiC at higher energies (not less than 0.662 MeV) of 137Cs sources... f The linear decay coefficient and mass decay coefficient of the / Si3N4-WBSP composite material are 0.242 cm⁻¹. -1 and 0.103 cm 2 / g, when the thickness of the composite material is greater than 0.84cm, the shielding effect can reach more than 70%;

[0029] Regarding microwave absorption performance, SiC exhibits superior performance in the X-band under conditions ranging from 8.2 to 12.4 GHz. fThe real part, imaginary part and dielectric loss tangent of the average dielectric constant of the / Si3N4-WBSP composite material are about 7.90, 4.56 and 0.58 respectively, when the thickness of the composite material is 2.64 mm, the RL value can reach full-frequency absorption below -9 dB, the electromagnetic wave absorption rate is about 87% or more, and the effective wave absorption bandwidth is 3.52 GHz.

[0030] The material is used in a high-temperature irradiation complex environment with a temperature of 1350 DEG C, a radiation source energy of 0.662 MeV and an electromagnetic wave frequency of 12.4 GHz, and meanwhile, good shielding performance and stealth performance are maintained, wherein the shielding effect and the electromagnetic wave absorption rate can reach 70% and 87% or more respectively under room temperature environment conditions; when the environmental temperature is 1350 DEG C, the SiC f The shielding effect and the electromagnetic wave absorption rate of the / Si3N4-WBSP composite material decrease, and can reach 54% and 85% or more respectively.

[0031] In the application: after BN interface and Si3N4 protective layer are deposited on the surface of the SiC fiber cloth, W, B4C and Sm2O3 (WBS) functional component particles are introduced into the SiC preform by using the coating and laying method, and polycarbosilane (PCS) is also introduced, the introduction of the WBS functional component makes the composite material have good shielding performance and wave absorption performance, and the PCS is the precursor of SiC, and after heat treatment, the PCS is crosslinked, solidified and cracked to be transformed into SiC ceramic phase with good thermal stability and mechanical performance. On the one hand, the addition of the PCS can contain the WBS phase, so that the WBS phase is physically isolated from the Si3N4 matrix, the reaction and diffusion of Sm2O3 in the WBS phase and the Si3N4 matrix are prevented, and the generation of Sm-Si-O-N glass phase is inhibited. On the other hand, Sm2O3 in the WBS phase will directly react with the SiC formed by the cracking of the PCS at high temperature to form a stable silicate phase, so that the Sm element is fixed in the WBSP phase. In addition, the PCS itself has certain adhesion, so it can also be used as a binder. The SiC ceramic phase formed by the cracking of the PCS can improve the strength of the WBS phase and improve the interlayer bonding of the composite material, so as to improve the mechanical properties of the / Si3N4-WBS composite material at high temperature. f The / Si3N4-WBS composite material has high-temperature mechanical properties, and meanwhile, the original shielding performance and wave absorption performance of the composite material are retained, and the service temperature of the material is increased to about 1350 DEG C. The changed components in the application are not simple and can be determined.

[0032] The application has the advantages and beneficial effects that: on the basis of WBS (W-B4C-Sm2O3) functional group particles, polycarbosilane (PCS) functional group particles are added to form a new WBSP (W-B4C-Sm2O3-PCS) functional filling material, and the new WBSP functional filling material is introduced into a SiC preform fiber cloth through a coating and laying method, and an interface and a matrix are deposited through a CVI process, so that a high-temperature-resistant-irradiation-resistant-stealth multi-functional integrated ceramic matrix composite material can be prepared, the preparation method can prevent the generation of Sm-Si-O-N glass phase, and at the same time, the problems of poor interlayer bonding of SiC f / Si3N4-WBS composite materials, the mechanical properties of the ceramic matrix radiation shielding material in a high-temperature environment are improved, the multi-functionality and high-temperature environment durability of the ceramic matrix composite material are improved, and the application range of the ceramic matrix composite material is expanded. f BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The SiC f / Si3N4-W-B4C-Sm2O3-SiC composite material is prepared according to the process flowchart of the application.

[0034] Figure 2 The SiC f / Si3N4-W-B4C-Sm2O3-SiC composite material is prepared according to the process flowchart of the application.

[0035] Figure 3 The SiC f / Si3N4-W-B4C-Sm2O3-SiC composite material is prepared according to the process flowchart of the application. f / Si3N4-W-B4C-Sm2O3 composite material is prepared according to the process flowchart of the application. 241 Am and 137 Cs radioactive sources.

[0036] Figure 4 The SiC f / Si3N4-W-B4C-Sm2O3-SiC composite material is prepared according to the process flowchart of the application. DETAILED DESCRIPTION ​

[0037] The application will be further described in connection with the embodiments and drawings as follows:

[0038] The application discloses a preparation method of a high-temperature-resistant, radiation-resistant and stealth multifunctional integrated ceramic matrix composite material.

[0039] a. Preparation of mixed coating slurry: W powder, B4C powder and Sm2O3 powder are mixed in a certain proportion, and then ball milled to form a mixed powder, which is then mixed with ultrapure water and stirred uniformly, and then mixed with polycarbosilane (PCS) in a certain proportion to prepare a mixed coating slurry.

[0040] Further, the mixed powder in step a is mixed in a proportion of 50% to 60% of tungsten (W) powder, 20% to 30% of boron carbide (B4C) powder and 10% to 20% of samarium oxide (Sm2O3) powder by volume fraction, and the ball-to-material ratio is 7:1 to 9:1 in the ball milling process, and the ball milling time is 24 hours to prepare the mixed powder.

[0041] Further, the mixed coating slurry in step a is mixed with ultrapure water in a mass ratio of 4:1 to 6:1, and then mixed uniformly in an electric mixer at a rotating speed of 200 to 400 rmp for 10 to 15 minutes, and finally 50 to 60 wt% of polycarbosilane (PCS) is added to prepare the mixed coating slurry.

[0042] b. Preparation of SiC preform cloth: a ruler is used to measure the size of the fiber cloth, a small knife is used to cut the fiber cloth to a specified number according to the size, and a clamp is used to fix the fiber cloth. A CVI process is used to deposit boron nitride (BN) interface and silicon nitride (Si3N4) protective layer on the SiC fiber cloth in the clamp in sequence.

[0043] Further, the SiC fiber cloth in step b is a two-dimensional woven structure SiC fiber cloth, and the size is 300mm×200mm, and the number of cutting is 8 to 10.

[0044] Further, the CVI process in step b uses boron trichloride (BCl3) and ammonia (NH3) as the precursor gas source for depositing the BN interface, wherein BCl3 is the boron source, NH3 is the nitrogen source, argon (Ar) is the carrier gas, hydrogen (H2) is the dilution gas, the gas flow rates are 20 to 30 ml / min, 60 to 70 ml / min, 100 to 120 ml / min and 100 to 120 ml / min respectively, the deposition time is 160 to 260 hours, the deposition temperature is 650 to 850℃, and the thickness is about 450 to 500 nm.

[0045] Further, the precursor gas source for depositing the Si3N4 protective layer by the CVI process in step b is silicon tetrachloride (SiCl4) and ammonia (NH3), wherein SiCl4 is the silicon source, NH3 is the nitrogen source, the carrier gas is argon (Ar), the dilution gas is hydrogen (H2), the gas flow rates are 100-110 ml / min, 60-70 ml / min, 100-120 ml / min, and 100-120 ml / min, respectively, the deposition time is 120-220 h, the deposition temperature is 800-1000°C, and the thickness is about 2.5-4.5 .

[0046] c. Preparation of the Si3N4 matrix: the mixed coating slurry prepared in step a is uniformly coated on the surface of the SiC preform prepared in step b by using a brush and then stacked and fixed, and then the Si3N4 matrix is deposited by the CVI process to densify the SiC preform.

[0047] Further, the precursor gas source for densifying the matrix by the CVI process in step c is silicon tetrachloride (SiCl4) and ammonia (NH3), wherein SiCl4 is the silicon source, NH3 is the nitrogen source, the carrier gas is argon (Ar), the dilution gas is hydrogen (H2), the gas flow rates are 100-110 ml / min, 60-70 ml / min, 100-120 ml / min, and 100-120 ml / min, respectively, and the deposition temperature is 800-1000°C.

[0048] Example 1:

[0049] In this example, the SiC f The SiC / Si3N4-W-B4C-Sm2O3-SiC composite material contains 50 wt% of polycarbosilane (PCS) and has a thickness of 2.22 mm.

[0050] a. Preparation of the mixed coating slurry: W powder, B4C powder, and Sm2O3 powder are mixed in a volume ratio of 5:3:2, and then the mixed powder is placed in a ball mill jar and ball milled for 24 h at a ball-to-powder ratio of 6:1 to form a mixed powder. Then, the uniformly mixed powder is ground and sieved to obtain a filler powder mixture. The filler powder mixture and a solution carrier (water and dimethylbenzene) are placed in a beaker in a mass ratio of 4:1, and then mixed uniformly by using an electric stirrer at a speed of 200 rpm for 10 min to obtain a mixed slurry in a non-fluid state. Finally, the mixed slurry is mixed and stirred with PCS precursors in a mass ratio of 1:1 to obtain a mixed coating slurry.

[0051] b. Preparation of SiC preform cloth: A ruler was used to measure the size of the 2D SiC fiber cloth to be 300 mm x 200 mm, and a small knife was used to cut the fiber cloth according to the size. A total of 8 pieces were cut, and they were soaked in anhydrous ethanol for ultrasonic cleaning to remove surface impurities. After drying, they were aligned and stacked. The prepared SiC fiber cloth was fixed using a graphite clamp, and graphite bolts were used to fix it around the edges to ensure the flatness of the SiC fiber cloth. Then, a BN interface was deposited using the CVI process. The precursor gas sources used were boron trichloride (BC13) and ammonia (NH3), where BCl3 was the boron source and NH3 was the nitrogen source. The carrier gas was argon (Ar), and the dilution gas was hydrogen (H2). The gas flow rates were 20 ml / min, 60 ml / min, 100 ml / min, and 100 ml / min, respectively. The deposition time was 160 h, and the deposition temperature was 650°C. The thickness was about 450 nm. Then, a Si3N4 protective layer was deposited using the CVI process. The precursor gas sources used were silicon tetrachloride (SiCl4) and ammonia (NH3), where SiCl4 was the silicon source and NH3 was the nitrogen source. The carrier gas was argon (Ar), and the dilution gas was hydrogen (H2). The gas flow rates were 100 ml / min, 60 ml / min, 100 ml / min, and 100 ml / min, respectively. The deposition time was 120 h, and the deposition temperature was 800°C. The thickness was about 2.5 .

[0052] c. Preparation of Si3N4 matrix: The mixed coating slurry prepared in step a was uniformly coated on the surface of the SiC fiber preform cloth prepared in step b using a brush. The preform cloth with multiple layers of coating slurry was then stacked and fixed with a graphite clamp. Finally, the Si3N4 matrix was densified using the CVI process. The precursor gas sources used were silicon tetrachloride (SiCl4) and ammonia (NH3), where SiCl4 was the silicon source and NH3 was the nitrogen source. The carrier gas was argon (Ar), and the dilution gas was hydrogen (H2). The gas flow rates were 100 ml / min, 60 ml / min, 100 ml / min, and 100 ml / min, respectively. The deposition temperature was 800°C.

[0053] Example 2:

[0054] In this example, the SiC f The SiC / Si3N4-W-B4C-Sm2O3-SiC composite material contains 55 wt% of polycarbosilane (PCS) with a thickness of 2.49 mm.

[0055] a. Preparation of mixed coating slurry: W powder, B4C powder and Sm2O3 powder are mixed in a volume ratio of 6:2:2, then the mixed powder is put into a ball mill tank, and ball milling is carried out at a ball-to-powder ratio of 8:1 for 24 h to form a mixed powder. Then, the uniformly mixed powder is ground and sieved to obtain a filler powder mixture. The filler powder mixture and the solution carrier (water and dimethylbenzene) are placed in a beaker in a mass ratio of 5:1, and mixed uniformly using an electric stirrer at a speed of 300 rmp for 12 min to obtain a mixed slurry in a non-fluid state. Finally, the mixed slurry is mixed and stirred with the PCS precursor in a mass ratio of 11:9 to obtain a mixed coating slurry.

[0056] b. Preparation of SiC preform cloth: A ruler is used to measure the size of the 2D SiC fiber cloth to be 300 mm x 200 mm, and a small knife is used to cut the fiber cloth according to the size. A total of 9 pieces of fiber cloth are cut, and then they are soaked in anhydrous ethanol for ultrasonic cleaning to remove surface impurities. After drying, the fiber cloths are aligned and stacked. Graphite clamps are used to fix the arranged SiC fiber cloths, and graphite bolts are used to fix them around to ensure the flatness of the SiC fiber cloths. Then, a BN interface is deposited using the CVI process. The precursor gas sources used are boron trichloride (BCl3) and ammonia (NH3), where BCl3 is the boron source and NH3 is the nitrogen source. The carrier gas is argon (Ar), and the dilution gas is hydrogen (H2). The gas flow rates are 25 ml / min, 65 ml / min, 110 ml / min, and 110 ml / min, respectively. The deposition time is 210 h, and the deposition temperature is 750°C. The thickness is about 475 nm. Then, a Si3N4 protective layer is deposited using the CVI process. The precursor gas sources used are silicon tetrachloride (SiCl4) and ammonia (NH3), where SiCl4 is the silicon source and NH3 is the nitrogen source. The carrier gas is argon (Ar), and the dilution gas is hydrogen (H2). The gas flow rates are 105 ml / min, 65 ml / min, 110 ml / min, and 110 ml / min, respectively. The deposition time is 170 h, and the deposition temperature is 900°C. The thickness is about 3.5 .

[0057] c. Preparation of Si3N4 matrix: The mixed coating slurry prepared in step a is uniformly coated on the surface of the SiC fiber preform cloth prepared in step b by using a brush, and then the preform cloth with multiple layers of coating slurry is stacked and fixed with a graphite clamp. Finally, the Si3N4 matrix is densified by using the CVI process, and the precursor gas sources used are silicon tetrachloride (SiCl4) and ammonia gas (NH3), wherein SiCl4 is the silicon source, NH3 is the nitrogen source, the carrier gas is argon (Ar), and the dilution gas is hydrogen (H2). The gas flow rates are 105 ml / min, 65 ml / min, 110 ml / min, and 110 ml / min, respectively, and the deposition temperature is 900°C.

[0058] Example 3:

[0059] In this example, the SiC f The Si3N4-W-B4C-Sm2O3-SiC composite material contains 60wt% of polycarbosilane (PCS) and has a thickness of 2.77mm.

[0060] a. Preparation of mixed coating slurry: W powder, B4C powder, and Sm2O3 powder are mixed in a volume ratio of 6:3:1, and then the mixed powder is placed in a ball mill jar and ball milled for 24h at a ball-to-powder ratio of 9:1 to form a mixed powder. Then, the uniformly mixed powder is ground and sieved to obtain a filler powder mixture. The filler powder mixture and the solution carrier (water and dimethylbenzene) are placed in a beaker in a mass ratio of 6:1, and then mixed uniformly by using an electric stirrer at a speed of 400rmp for 15 min to obtain a mixed slurry in a non-fluid state. Finally, the mixed slurry is mixed and stirred with the PCS precursor in a mass ratio of 3:2 to obtain a mixed coating slurry.

[0061] b. Preparation of SiC preform cloth: use a ruler to measure the size of the 2D SiC fiber cloth to be 300mm x 200mm, use a small knife to cut the fiber cloth according to the size, a total of 10 pieces are cut, and they are soaked in anhydrous ethanol for ultrasonic cleaning to remove surface impurities, dried, aligned and stacked. The prepared SiC fiber cloth is fixed using a graphite clamp, and is fixed around using graphite bolts to ensure the flatness of the SiC fiber cloth; then BN interface is deposited by CVI process, the precursor gas source used is boron trichloride (BCl3) and ammonia (NH3), wherein BCl3 is a boron source, NH3 is a nitrogen source, the carrier gas is argon (Ar), the dilution gas is hydrogen (H2), the gas flow rates are 30ml / min, 70ml / min, 120ml / min, 120ml / min, respectively, the deposition time is 260h, the deposition temperature is 850℃, and the thickness is about 500nm; then Si3N4 protective layer is deposited by CVI process, the precursor gas source used is silicon tetrachloride (SiCl4) and ammonia (NH3), wherein SiCl4 is a silicon source, NH3 is a nitrogen source, the carrier gas is argon (Ar), the dilution gas is hydrogen (H2), the gas flow rates are 110ml / min, 70ml / min, 120ml / min, 120ml / min, respectively, the deposition time is 220h, the deposition temperature is 1000℃, and the thickness is about 4.5 .

[0062] c. Preparation of Si3N4 matrix: the mixed coating slurry prepared in step a is uniformly coated on the surface of the SiC fiber preform cloth prepared in step b by using a brush, the preform cloth with multiple layers of coating slurry is stacked and fixed by using a graphite clamp, and finally the Si3N4 matrix is densified by CVI process, the precursor gas source used is silicon tetrachloride (SiCl4) and ammonia (NH3), wherein SiCl4 is a silicon source, NH3 is a nitrogen source, the carrier gas is argon (Ar), the dilution gas is hydrogen (H2), and the gas flow rates are 110ml / min, 70ml / min, 120ml / min, 120ml / min, respectively, and the deposition temperature is 1000℃.

[0063] According to the embodiments 1-3 of the present application, other components, ratios and specific preparation process parameters can be selected according to actual needs, and the technical effects described in the present application can be achieved, therefore, the present application will not be listed and described one by one.

[0064] According to the embodiments 1-3 of the present application and the drawings, the beneficial effects of the present application can be seen:

[0065] Figure 2 .SiC fSEM images and EDS area scan results of the internal microstructure of SiCf / Si3N4-W-B4C-Sm2O3-SiC composite: (a) distribution characteristics of the morphology of each component at low magnification, (b) matrix structure characteristics, (c) fiber bundle morphology characteristics, and (d) morphology of each component of a single fiber.

[0066] Overall, the composite is composed of SiC fiber bundles in the gray area and W-B4C-Sm2O3-SiC (WBSP) functional phases between the fiber bundles. Compared with SiC f Compared with SiC f The SiCf / Si3N4-WBSP composite has more uniform pore distribution and more uniform pore size, and is mainly composed of closed small and medium-sized pores, which are significantly smaller than the SiC f In the SiCf / Si3N4-WBS composite, there are also intra-bundle pores due to the "bottleneck effect" of the CVI process. The WBSP phase has a clear boundary with the Si3N4 matrix phase, and no reaction occurs, and no SiC f The white Sm-Si-O-N glass phase appears in the SiCf / Si3N4-WBS composite. The addition of PCS in the functional filler effectively improves the compatibility of the functional filler and the Si3N4 matrix, and inhibits the generation of the Sm-Si-O-N glass phase. The interface phase in all fiber bundles is intact, and no penetration and erosion of the glass phase to the interface is found. The SiC f The SiCf / Si3N4-WBSP composite does not form a white glass phase-rich area around the pores and the outer edge of the fiber bundle, and the fibers, interfaces and protective layer matrix at the outer edge of the fiber bundle are almost intact in morphology, and are closely attached to each other. In addition, it is observed that the WBSP phase has discontinuities, which are filled with Si3N4 phase. This may be because the PCS volume shrinks during high-temperature cracking in the Si3N4 matrix deposition process, resulting in shrinkage of the WBSP phase as a whole, generating a large number of cracks. These cracks are filled with the deposited Si3N4 matrix, forming discontinuities.

[0067] Figure 3 . SiC f Compared with SiC f Comparison of the radiation shielding performance of SiCf / Si3N4-W-B4C-Sm2O3-SiC composite and SiCf / Si3N4-W-B4C-Sm2O3 composite under 241Am and 137Cs radiation sources: shielding efficiency.

[0068] For low-energy photons, SiCf / Si3N4-WBS and SiC fThe material thickness required for / Si3N4-WBSP composite material to achieve 70% shielding rate is 0.47 cm and 0.84 cm, and the material thickness required to achieve 90% shielding rate is 0.91 cm and 1.60 cm. It can be seen that to achieve higher shielding efficiency, SiC f / Si3N4-WBS and SiC f The gap of material thickness required for / Si3N4-WBSP composite material gradually increases, but the thickness required for both types of composite materials is small for shielding low-energy photons; and in the higher energy region, SiC f The radiation shielding performance of / Si3N4-WBSP composite material is slightly weaker than that of SiC f / Si3N4-WBS, but as the thickness increases, the shielding efficiency of the two materials gradually tends to be the same. Therefore, for SiC f / Si3N4-WBS composite material, the optimized SiC f / Si3N4-WBSP composite material does not show obvious performance degradation for shielding relatively high-energy photons, SiC f / Si3N4-WBSP composite material has far superior mechanical properties to SiC f / Si3N4-WBS composite material.

[0069] Figure 4 .SiC f Load-displacement curves and SEM fracture morphology of / Si3N4-W-B4C-Sm2O3-SiC composite material at high temperature: (i), (ii) and (iii) are the fracture of the material at 1100℃, 1200℃ and 1350℃, respectively (low magnification).

[0070] Figure 4 is to SiC f / Si3N4-WBSP composite material was subjected to high-temperature bending test at different temperatures. With the increase of test temperature, SiC f The bending strength of / Si3N4-WBSP composite material continues to decline, and at 800℃, 1100℃ and 1350℃, the bending strength is 313.86 MPa, 256.39 MPa and 203.04 MPa, respectively, which is 15.18%, 30.71% and 45.13% lower than the room temperature strength, respectively. Compared with SiC f / Si3N4-WBS composite material, the bending strength of SiC f The mechanical properties of / Si3N4-WBSP composite material are obviously improved, and at 1350℃ high temperature, the bending strength of the material is still more than 200 MPa, even greater than that of SiC f / Si3N4-WBS composite material at room temperature. Compared with SiCf The fracture mode of / Si3N4-WBS composite at high temperature obviously changed to brittle fracture, SiC f The fracture mode of / Si3N4-WBSP composite at 800 ℃ and 1100 ℃ was still pseudo-plastic fracture, and the fracture work was greater than the test results at room temperature, indicating that the toughness of the material improved at high temperature. When the temperature reached 1350 ℃, the material appeared brittle fracture mode, but the material still had a high fracture work. And with the increase of temperature, the displacement of load reaching the maximum value gradually increased, and SiC f / Si3N4-WBS composite, SiC f The toughness and strength of / Si3N4-WBSP composite were more obvious with the increase of temperature.

Claims

1. A method for preparing a high-temperature-resistant, radiation-resistant, and stealth multifunctional integrated ceramic matrix composite material, characterized in that The steps are as follows: Step 1: a plurality of SiC fiber cloths are sequentially deposited with boron nitride BN interface and silicon nitride Si3N4 protective layer by using CVI process; When the boron nitride BN interface is deposited, the precursor gas source is boron trichloride BCl3 and ammonia NH3, wherein BCl3 is a boron source, NH3 is a nitrogen source, the carrier gas is argon Ar, and the dilution gas is hydrogen H2; When the silicon nitride Si3N4 protective layer is deposited, the precursor gas source is silicon tetrachloride SiCl4 and ammonia NH3, wherein SiCl4 is a silicon source, NH3 is a nitrogen source, the carrier gas is argon Ar, and the dilution gas is hydrogen H2; Step 2: the mixed coating slurry is coated on the surface of each SiC prepreg cloth deposited in step 1, and then a plurality of SiC prepreg cloths are stacked and fixed; The mixed coating slurry is a mixed powder of 50-60% by volume W powder, 20-30% B4C powder and 10-20% Sm2O3 powder mixed with ultrapure water, and then poly-carbosilane PCS is added; The added poly-carbosilane PCS is 50-60wt%; Step 3: Si3N4 matrix is deposited by using CVI process to densify the SiC prepreg cloth, and a high-temperature-resistant, radiation-resistant and stealth multi-functional integrated ceramic matrix composite material is obtained; When the Si3N4 matrix is deposited by using CVI process, the precursor gas source is silicon tetrachloride SiCl4 and ammonia NH3, wherein SiCl4 is a silicon source, NH3 is a nitrogen source, the carrier gas is argon Ar, and the dilution gas is hydrogen H2; The structure of the multifunctional integrated ceramic matrix composite prepared by the above steps is SiC f / Si3N4-W-B4C-Sm2O3-SiC, comprising SiC fiber cloth, a boron nitride BN interface with a thickness of 450-500 nm provided on the SiC fiber cloth; the BN interface is provided with silicon nitride Si3N4 with a thickness of 2.5-4.5 μm; the SiC fiber cloth is provided with WBS functional component particles and polycarbosilane PCS functional component particles, forming a WBSP functional filling material; the overall structure is densified by a CVI process; the SiC f / Si3N4-WBSP composite material has a densification degree of not less than 85%; the SiC f / Si3N4-WBSP composite material has a linear attenuation coefficient and a mass attenuation coefficient of 0.242 cm -1 and 0.103 cm 2 / g, respectively; the shielding effect reaches more than 70%; the RL value reaches full-frequency absorption of less than -9 dB, the electromagnetic wave absorption rate is more than 87%, and the effective wave absorption bandwidth is 3.52 GHz; The WBS is a mixture of W-B4C-Sm2O3, and the WBSP is a mixture of W-B4C-Sm2O3-PCS.

2. The method for preparing the high-temperature-resistant, radiation-resistant, and stealth multi-functional integrated ceramic matrix composite material according to claim 1, characterized in that: The SiC prepreg cloth is a two-dimensional woven structure SiC fiber cloth.

3. The method for preparing the high-temperature-resistant, radiation-resistant, and stealth multi-functional integrated ceramic matrix composite material according to claim 1, characterized in that: The plurality of SiC fiber cloths is 8-10.

4. The method for preparing the high-temperature-resistant, radiation-resistant, and stealth multi-functional integrated ceramic matrix composite material according to claim 1, characterized in that: The deposition time of the deposited boron nitride BN interface is 160-260h, and the deposition temperature is 650-850℃; the gas flow ratio is: boron source BCl3 is 20-30ml / min, nitrogen source NH3 is 60-70ml / min, carrier gas argon Ar is 100-120ml / min, and dilution gas hydrogen H2 is 100-120ml / min.

5. The method for preparing the high-temperature-resistant, radiation-resistant, and stealth multi-functional integrated ceramic matrix composite material according to claim 1, characterized in that: The deposition time of the deposited silicon nitride Si3N4 protective layer is 120-220h, and the deposition temperature is 800-1000℃; the gas flow ratio is: silicon source SiCl4 is 100-110ml / min, nitrogen source NH3 is 60-70ml / min, carrier gas argon Ar is 100-120ml / min, and dilution gas hydrogen H2 is 100-120ml / min.

6. The method for preparing the high-temperature-resistant, radiation-resistant, and stealth multi-functional integrated ceramic matrix composite material according to claim 1, characterized in that: When the CVI process densifies the matrix in step 3, the deposition temperature is 800-1000℃; the gas flow ratio is: silicon source SiCl4 is 100-110ml / min, nitrogen source NH3 is 60-70ml / min, carrier gas argon Ar is 100-120ml / min, and dilution gas hydrogen H2 is 100-120ml / min.

7. The method for preparing the high-temperature-resistant, radiation-resistant, and stealth multi-functional integrated ceramic matrix composite material according to claim 1, characterized in that: The mixed powder of the W powder, the B4C powder and the Sm2O3 powder is prepared by a ball milling process, a ball-to-material ratio is 7:1-9:1, and a ball milling time is 24 h.

8. The method for preparing the high-temperature-resistant, radiation-resistant, and stealth multi-functional integrated ceramic matrix composite material according to claim 1, characterized in that: The ratio of the mixed powder to the ultrapure water in the mixed coating slurry is 4:1-6:1 in mass ratio.

9. The high-temperature resistant, radiation resistant, and stealthy multifunctional integrated ceramic matrix composite material prepared by the method of any one of claims 1-8. The structure of the multifunctional integrated ceramic matrix composite material is SiC f / Si3N4-W-B4C-Sm2O3-SiC, comprising a SiC fiber cloth, a boron nitride BN interface with a thickness of 450-500 nm provided on the SiC fiber cloth; the BN interface is provided with silicon nitride Si3N4 with a thickness of 2.5-4.5 μm; the SiC fiber cloth is provided with WBS functional component particles and polycarbosilane PCS functional component particles, forming a WBSP functional filling material; the overall structure is densified by a CVI process; the SiC f / Si3N4-WBSP composite material has a densification degree of not less than 85%; the SiC f / Si3N4-WBSP composite material has a linear attenuation coefficient and a mass attenuation coefficient of 0.242 cm -1 and 0.103 cm 2 / g, respectively; the shielding effect reaches more than 70%; the RL value reaches full-frequency absorption of less than -9 dB, the electromagnetic wave absorption rate is more than 87%, and the effective wave absorption bandwidth is 3.52 GHz.

10. The use of the high-temperature-resistant, radiation-resistant, and stealth multi-functional integrated ceramic matrix composite material according to claim 9, characterized in that: The application is used in high temperature irradiation complex environment with temperature up to 1350 DEG C, radioactive source energy and electromagnetic wave frequency being 0.662 MeV and 12.4 GHz respectively; meanwhile, good shielding performance and stealth performance are maintained, wherein the shielding effect and electromagnetic wave absorption rate are above 70% and 87% respectively under room temperature environment condition; when the environmental temperature is 1350 DEG C, the SiC f The shielding effect and electromagnetic wave absorption rate of the SiC / Si3N4-WBSP composite material are decreased, and are above 54% and 85% respectively.

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