Preparation method of high-temperature-resistant, radiation-resistant and stealth multifunctional integrated ceramic-based composite material

Abstract

The invention relates to a preparation method of a high-temperature-resistant, radiation-resistant and stealth multifunctional integrated ceramic matrix composite material. The preparation method comprises the following steps: a, preparing coating slurry containing functional filling particles by ball milling and preparing silicon carbide (SiC) prefabricated cloth by a chemical vapor infiltration (CVI) process; b, uniformly coating the surface of the SiC prefabricated cloth with the mixed slurry, and neatly stacking and fixing; and c, depositing a silicon nitride (Si3N4) matrix on the laminated and fixed prefabricated body by a CVI (Chemical Vapor Infiltration) process for densifying. According to the preparation method provided by the invention, the integration of a high-temperature-resistant, radiation-resistant and stealth multifunctional structure of the ceramic-based composite material is realized, the mechanical property of the ceramic-based radiation shielding material in a high-temperature environment is enhanced, and the multifunctionality and high-temperature environment durability of the ceramic-based composite material are improved; meanwhile, the application range of the ceramic-based composite material is expanded.

Description

Technical Field

[0001] The invention belongs to the technical field of radiation shielding materials, and relates to a method for preparing a high temperature resistant, radiation resistant and stealthy multifunctional integrated ceramic-based composite material. Background Art

[0002] With the development of aerospace, nuclear weapons, energy and other fields and the increase in the application of portable radiation sources, the requirements for radiation shielding materials are constantly increasing. Existing shielding materials are difficult to achieve compatibility between shielding performance, mechanical properties and high temperature resistance, and the degree of functional structural integration is low, which cannot meet the use requirements. Ceramic-based composite materials have high specific strength, excellent high temperature resistance and strong designability. They have been widely used in aviation, aerospace, nuclear energy and other fields, and are the preferred materials for achieving functional structural integration.

[0003] At present, in the field of radiation shielding protection, 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 small. The complexity of the application environment places increasingly higher requirements on the performance of radiation shielding materials. The materials should not only have excellent shielding properties, but also have good mechanical properties, high temperature resistance, and radiation resistance. Many existing shielding materials are difficult to meet the use requirements, mainly because the shielding properties of the materials are difficult to be compatible with other properties such as mechanical properties. Improving the structural / functional integration of shielding materials is an important direction of current and future research in this field. Therefore, in addition to optimizing traditional radiation shielding, the development of new and composite radiation shielding materials has great theoretical significance and application prospects. Summary of the invention

[0004] Technical issues to be solved

[0005] In order to avoid the shortcomings of the prior art, the present invention proposes a method for preparing a high temperature resistant, radiation resistant, and stealth multifunctional integrated ceramic matrix composite material to cope with the unfavorable situation that the comprehensive performance of radiation shielding materials is weak and the high temperature mechanical properties are poor in complex and harsh service environments. The high temperature resistant, radiation resistant, and stealth multifunctional integrated ceramic matrix composite material can be prepared by the CVI process and the coating and lamination method, which enhances the performance stability of the ceramic-based radiation shielding material in a thermal environment and an irradiation environment, improves the mechanical properties of the ceramic-based radiation shielding material in a high temperature environment, improves the multifunctionality and high temperature environment durability of the ceramic-based composite material, and expands the application range of the ceramic-based composite material.

[0006] Technical Solution

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

[0008] Step 1: Use CVI process to deposit boron nitride BN interface and silicon nitride Si on multiple SiC fiber cloths in sequence 3 N 4 Protective layer;

[0009] The precursor gas source when depositing the boron nitride BN interface is boron trichloride BCl 3 and ammonia NH 3 , where BCl 3 As the boron source, NH 3 The nitrogen source is argon gas, the carrier gas is Ar, and the dilution gas is hydrogen gas. 2 ;

[0010] The deposited silicon nitride Si 3 N 4 The precursor gas source for the protective layer is silicon tetrachloride SiCl 4 and ammonia NH 3 , where SiCl 4 As silicon source, NH 3 The nitrogen source is argon gas, the carrier gas is Ar, and the dilution gas is hydrogen gas. 2 ;

[0011] Step 2: applying the mixed coating slurry on the surface of each SiC prefabricated cloth deposited in step 1, and then stacking and fixing multiple SiC prefabricated cloths;

[0012] The mixed coating slurry is 50% to 60% by volume of W powder, 20% to 30% by volume of B 4 C powder and 10% to 20% Sm 2 O 3 The mixed powder of the powder is mixed with ultrapure water and then polycarbosilane PCS is added to make it;

[0013] The added polycarbosilane PCS is 50-60wt%; (relative to which percentage?)

[0014] Step 3: Deposit Si using CVI process 3 N 4 The matrix densifies the SiC prefabricated cloth to obtain a high temperature resistant, radiation resistant and stealthy multifunctional integrated ceramic matrix composite material;

[0015] The CVI process deposits Si 3 N 4 When the matrix is ​​formed, the precursor gas source is silicon tetrachloride SiCl 4 and ammonia NH 3 , where SiCl 4 As silicon source, NH 3 The nitrogen source is argon gas, the carrier gas is Ar, and the dilution gas is hydrogen gas. 2 .

[0016] The SiC prefabricated cloth is a SiC fiber cloth with a two-dimensional woven structure.

[0017] The number of the plurality of SiC fiber cloths is 8 to 10.

[0018] The deposition time of the BN interface is 160 to 260 hours, and the deposition temperature is 650 to 850° C. The gas flow ratio is: boron source BCl 3 The nitrogen source is NH 3 The flow rate of the carrier gas is 60-70 ml / min, the flow rate of the carrier gas argon (Ar) is 100-120 ml / min, and the flow rate of the diluent gas hydrogen (H) is 100-120 ml / min. 2 It is 100~120ml / min.

[0019] The deposited silicon nitride Si 3 N 4 The protective layer deposition time is 120-220h, the deposition temperature is 800-1000℃; the gas flow ratio is: silicon source SiCl 4 100~110ml / min, nitrogen source NH 3 The flow rate of the carrier gas is 60-70 ml / min, the flow rate of the carrier gas Ar is 100-120 ml / min, and the flow rate of the diluent gas hydrogen H is 2 It is 100~120ml / min.

[0020] When the CVI process in step 3 densifies the substrate, the deposition temperature is 800-1000° C. The gas flow ratio is: silicon source SiCl 4 100~110ml / min, nitrogen source NH 3 The flow rate of the carrier gas is 60-70 ml / min, the flow rate of the carrier gas Ar is 100-120 ml / min, and the flow rate of the diluent gas hydrogen H is 2 It is 100~120ml / min.

[0021] The W powder, B 4 C powder and Sm 2 O 3 The mixed powder is prepared by ball milling with a ball-to-material ratio of 7:1 to 9:1 and a ball milling time of 24 hours.

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

[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 / Si 3 N 4 -WB 4 C-Sm2 O 3 -SiC, including SiC fiber cloth, a boron nitride BN interface with a thickness of 450-500 nm on the SiC fiber cloth, and a silicon nitride Si with a thickness of 2.5-4.5 μm on the BN interface 3 N 4 The SiC fiber cloth is provided with WBS functional component particles and polycarbosilane PCS functional component particles, constituting WBSP (WB 4 C-Sm 2 O 3 -PCS) functional filling material; the overall structure is obtained by CVI process deposition and densification; the SiC f / Si 3 N 4 -The densification degree of WBSP composite material is not less than 85%; SiC f / Si 3 N 4 The linear attenuation coefficient and mass attenuation coefficient of the WBSP composite material are 0.242 cm -1 and 0.103cm 2 / g; shielding effect is over 70%; RL value can reach full-frequency absorption below -9dB, electromagnetic wave absorption rate is about over 87%, and effective absorption bandwidth is 3.52GHz.

[0024] An application of the high temperature resistant, radiation resistant and stealth multifunctional integrated ceramic matrix composite material is characterized in that: it is used in a high temperature irradiation complex environment with a temperature of up to 1350°C, a radiation source energy of 0.662MeV and an electromagnetic wave frequency of 12.4GHz respectively; while maintaining good shielding performance and stealth performance, wherein under room temperature conditions, the shielding effect and electromagnetic wave absorption rate can reach 70% and 87% or more respectively; when the ambient temperature is 1350°C, SiC f / Si 3 N 4 -The shielding effect and electromagnetic wave absorption rate of WBSP composite materials have decreased, reaching 54% and more than 85% respectively.

[0025] Beneficial Effects

[0026] The present invention proposes a method for preparing a high temperature resistant, radiation resistant and stealth multifunctional integrated ceramic matrix composite material, comprising the following steps: a. preparing a coating slurry containing functional filling particles by ball milling and preparing a silicon carbide (SiC) prefabricated cloth by chemical vapor infiltration (CVI) process; b. uniformly coating the mixed slurry on the surface of the SiC prefabricated cloth and stacking and fixing it neatly; c. depositing silicon nitride (SiC) on the stacked and fixed prefabricated body by CVI process 3 N 4The preparation method provided by the present invention realizes the integration of high temperature resistance, radiation resistance and stealth multifunctional structure of ceramic-based composite materials, strengthens the mechanical properties of ceramic-based radiation shielding materials in high temperature environments, improves the multifunctionality and high temperature environment durability of ceramic-based composite materials, and expands the application range of ceramic-based composite materials.

[0027] In terms of densification, the material of the present invention has SiC f / Si 3 N 4 - The densification degree of the WBSP composite material is not less than 85%;

[0028] In terms of radiation resistance, at a higher energy (not less than 0.662MeV) 137Cs source, SiC f / Si 3 N 4 The linear attenuation coefficient and mass attenuation coefficient of the WBSP composite material are 0.242 cm -1 and 0.103cm 2 / g, when the thickness of the composite material is greater than 0.84cm, the shielding effect can reach more than 70%;

[0029] In terms of wave absorption performance, SiC f / Si 3 N 4 The real part, imaginary part and dielectric loss tangent of the average dielectric constant of the -WBSP composite material are approximately 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 approximately more than 87%, and the effective absorption bandwidth is 3.52 GHz.

[0030] The material of the present invention is used in a high temperature irradiation complex environment with a temperature of up to 1350°C, a radiation source energy of 0.662MeV and an electromagnetic wave frequency of 12.4GHz respectively, while maintaining good shielding performance and stealth performance. Under room temperature conditions, the shielding effect and electromagnetic wave absorption rate can reach 70% and 87% respectively; when the ambient temperature is 1350°C, SiC f / Si 3 N 4 -The shielding effect and electromagnetic wave absorption rate of WBSP composite materials have decreased, reaching 54% and more than 85% respectively.

[0031] In the present invention, due to the deposition of BN interface and Si on the surface of SiC fiber cloth 3 N 4 After the protective layer, the coating method is used to introduce not only W, B 4 C. Sm2 O 3 The WBS functional component particles are also introduced with polycarbosilane (PCS). The introduction of WBS functional component makes the composite material have good shielding and wave absorbing properties. PCS, as a precursor of SiC, undergoes cross-linking, curing, and cracking after heat treatment, and then transforms into a SiC ceramic phase with good thermal stability and mechanical properties. On the one hand, the addition of PCS can contain the WBS phase, making it compatible with SiC. 3 N 4 Produce physical isolation, preventing Sm in WBS phase 2 O 3 With Si 3 N 4 The reaction diffusion of the matrix inhibits the formation of Sm-Si-ON glass phase. On the other hand, the Sm in the WBS phase 2 O 3 At high temperatures, it will directly react with SiC formed by PCS cracking to form a stable silicate phase, fixing the Sm element in the WBSP phase. In addition, PCS itself has certain adhesive properties, so it can also be used as a binder. The SiC ceramic phase generated by PCS cracking can increase the strength of the WBS phase and improve the interlayer bonding of the composite material to improve the SiC f / Si 3 N 4 -WBS composite material high temperature mechanical properties, while retaining the original shielding performance and wave absorbing performance of the composite material, the material service environment temperature is increased to about 1350 ° C. The components changed in the present invention cannot be simply determined.

[0032] By adopting the above technical solution, the advantages and beneficial effects of the present invention are: 4 C-Sm 2 O 3 ) functional component particles are added with polycarbosilane (PCS) functional component particles to form a new WBSP (WB 4 C-Sm 2 O 3 -PCS) functional filling material, and introduce the new WBSP functional filler into the SiC prefabricated fiber cloth by coating and laying method, and use CVI process to deposit the interface and matrix to prepare high temperature resistant, radiation resistant and stealth multifunctional integrated ceramic matrix composite material. This preparation method can prevent the formation of Sm-Si-ON glass phase and improve the SiC f / Si 3 N 4 -Poor bonding between layers of WBS composite materials, SiC f / Si 3 N 4-WBSP composite materials enhance the mechanical properties of ceramic-based radiation shielding materials in high-temperature environments, improve the versatility and durability of ceramic-based composite materials in high-temperature environments, and expand the application range of ceramic-based composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Preparation of SiC for the embodiment of the present invention f / Si 3 N 4 -WB 4 C-Sm 2 O 3 -Process flow chart of SiC composite materials;

[0034] Figure 2 SiC prepared in the embodiment of the present invention f / Si 3 N 4 -WB 4 C-Sm 2 O 3 -Scanning electron microscope (SEM) image and EDS spectrum of the cross section of SiC composite material, (a) morphology distribution characteristics of each component at low magnification, (b) matrix structure characteristics, (c) fiber bundle morphology characteristics, it can be seen that the outer side of the fiber bundle and the outer structure are intact, (d) morphology of each component of a single fiber;

[0035] Figure 3 SiC prepared in the embodiment of the present invention f / Si 3 N 4 -WB 4 C-Sm 2 O 3 -SiC composite materials and SiC f / Si 3 N 4 -WB 4 C-Sm 2 O 3 Composite materials in 241 Am and 137 Comparison of radiation shielding performance under Cs radiation source;

[0036] Figure 4 SiC prepared in the embodiment of the present invention f / Si 3 N 4 -WB 4 C-Sm 2 O 3 -Load-displacement curve and fracture SEM morphology of SiC composite materials at high temperature. (i), (ii) and (iii) are the fracture surfaces of materials at 800℃, 1100℃ and 1350℃ respectively (low magnification). DETAILED DESCRIPTION

[0037] The present invention will now be further described with reference to the embodiments and the accompanying drawings:

[0038] A method for preparing a high temperature resistant, radiation resistant and stealth multifunctional integrated ceramic matrix composite material, characterized by comprising the following steps:

[0039] a. Preparation of mixed coating slurry: W powder, B 4 C powder and Sm 2 O 3 The powders are mixed in a certain proportion, and after ball milling to form a mixed powder, the mixed powder is mixed with ultrapure water and stirred evenly, and then polycarbosilane (PCS) is added in a certain proportion to prepare a mixed coating slurry;

[0040] Furthermore, the mixed powder in step a comprises tungsten (W) powder, boron carbide (B 4 C) powder and samarium oxide (Sm 2 O 3 ) powders are mixed in proportion. In the ball milling process, the ball-to-material ratio is 7:1 to 9:1, and the ball milling time is 24 hours to prepare the mixed powder.

[0041] Furthermore, the mixed coating slurry described in step a is mixed with ultrapure water in a mass ratio of 4:1 to 6:1, and is evenly mixed in an electric stirrer at a speed of 200 to 400 rpm for 10-15 min, and finally 50 to 60 wt% of polycarbosilane (PCS) is added to prepare the mixed coating slurry.

[0042] b. Preparation of SiC prefabricated cloth: Use a ruler to measure the specified size of the SiC fiber cloth, use a knife to cut the specified number of pieces according to the size, and fix it with a clamp. Use the CVI process to deposit boron nitride (BN) interface and silicon nitride (SiC) on the SiC fiber cloth in the fixture. 3 N 4 ) protective layer;

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

[0044] Furthermore, the precursor gas source used in the CVI process for depositing the BN interface in step b is boron trichloride (BCl 3 ) and ammonia (NH 3 ), where BCl 3 As the boron source, NH 3The nitrogen source is argon (Ar), the carrier gas is argon (Ar), and the diluent gas is hydrogen (H 2 ), the gas flow rates are 20-30 ml / min, 60-70 ml / min, 100-120 ml / min, 100-120 ml / min, respectively; the deposition time is 160-260 h; the deposition temperature is 650-850 ° C; and the thickness is about 450-500 nm.

[0045] Further, the CVI process described in step b deposits Si 3 N 4 The precursor gas source used for the protective layer is silicon tetrachloride (SiCl 4 ) and ammonia (NH 3 ), where SiCl 4 As silicon source, NH 3 The nitrogen source is argon (Ar), the carrier gas is argon (Ar), and the diluent gas is hydrogen (H 2 ), the gas flow rates are 100-110 ml / min, 60-70 ml / min, 100-120 ml / min, 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 μm.

[0046] c.Si 3 N 4 Preparation of the substrate: Use a brush to evenly apply the mixed coating slurry prepared in step a to the surface of the SiC prefabricated cloth prepared in step b and laminate and fix them, then use the CVI process to deposit Si 3 N 4 The matrix densifies the SiC preform.

[0047] Furthermore, the precursor gas source used in the CVI process for densifying the matrix in step c is silicon tetrachloride (SiCl 4 ) and ammonia (NH 3 ), where SiCl 4 As silicon source, NH 3 The nitrogen source is argon (Ar), the carrier gas is argon (Ar), and the diluent gas is hydrogen (H 2 ), the gas flow rates are 100-110 ml / min, 60-70 ml / min, 100-120 ml / min, 100-120 ml / min respectively, and the deposition temperature is 800-1000°C.

[0048] Embodiment 1:

[0049] In this embodiment, the SiC prepared by the coating layer method f / Si 3 N 4 -WB 4 C-Sm2 O 3 The SiC composite material contained 50 wt% polycarbosilane (PCS) and had a thickness of 2.22 mm.

[0050] a. Preparation of mixed coating slurry: W powder, B 4 C powder and Sm 2 O 3 After the powders are mixed in a volume fraction ratio of 5:3:2, the mixed powders are placed in a ball mill and ball milled for 24 hours at a ball-to-material ratio of 6:1 to form a mixed powder. Then, the evenly mixed powders are ground and sieved to obtain a filler powder mixture. The filler powder mixture and the solution carrier (water and xylene) are placed in a beaker at a mass ratio of 4:1, and mixed evenly using an electric stirrer at a speed of 200 rpm and a stirring time of 10 min to obtain a mixed slurry in a non-fluid state. Finally, the mixed slurry is mixed and stirred with a PCS precursor at a mass ratio of 1:1 to prepare a mixed coating slurry.

[0051] b. Preparation of SiC prefabricated cloth: Use a ruler to measure the size of 300mm×200mm fiber cloth on the 2D SiC fiber cloth, and use a knife to cut it according to the size. A total of 8 sheets are cut, and they are soaked in anhydrous ethanol for ultrasonic cleaning. After removing surface impurities and drying, they are aligned and stacked. Use a graphite splint to fix the arranged SiC fiber cloth, and use graphite bolts to fix it around to ensure the flatness of the SiC fiber cloth; then use the CVI process to deposit the BN interface, and the precursor gas source used is boron trichloride (BCl 3 ) and ammonia (NH 3 ), where BCl 3 As the boron source, NH 3 The nitrogen source is argon (Ar), the carrier gas is argon (Ar), and the diluent gas is hydrogen (H 2 ), the gas flow rates were 20 ml / min, 60 ml / min, 100 ml / min, 100 ml / min, the deposition time was 160 h, the deposition temperature was 650 ° C, and the thickness was about 450 nm; then the CVI process was also used to deposit Si 3 N 4 The protective layer, the precursor gas source used is silicon tetrachloride (SiCl 4 ) and ammonia (NH 3 ), where SiCl 4 As silicon source, NH 3 The nitrogen source is argon (Ar), the carrier gas is argon (Ar), and the diluent gas is hydrogen (H 2 ), the gas flow rates are 100ml / min, 60ml / min, 100ml / min, 100ml / min, respectively, the deposition time is 120h, the deposition temperature is 800℃, and the thickness is about 2.5μm.

[0052] c.Si 3 N 4 Preparation of the substrate: The mixed coating slurry prepared in step a is evenly applied to the surface of the SiC fiber prefabricated cloth prepared in step b with a brush, and then multiple layers of prefabricated cloth coated with the slurry are stacked and fixed with a graphite clamp, and finally SiC fiber prefabricated cloth is processed by CVI process. 3 N 4 The matrix is ​​densified, and the precursor gas source used is silicon tetrachloride (SiCl 4 ) and ammonia (NH 3 ), where SiCl 4 As silicon source, NH 3 The nitrogen source is argon (Ar), the carrier gas is argon (Ar), and the diluent gas is hydrogen (H 2 ), the gas flow rates are 100ml / min, 60ml / min, 100ml / min, 100ml / min respectively, and the deposition temperature is 800℃.

[0053] Embodiment 2:

[0054] In this embodiment, the SiC prepared by the coating layer method f / Si 3 N 4 -WB 4 C-Sm 2 O 3 The SiC composite material contained 55 wt% polycarbosilane (PCS) and had a thickness of 2.49 mm.

[0055] a. Preparation of mixed coating slurry: W powder, B 4 C powder and Sm 2 O 3 After the powders are mixed in a volume fraction ratio of 6:2:2, the mixed powders are placed in a ball mill and ball-milled for 24 hours at a ball-to-material ratio of 8:1 to form a mixed powder. Then, the evenly mixed powders are ground and sieved to obtain a filler powder mixture. The filler powder mixture and the solution carrier (water and xylene) are placed in a beaker at a mass ratio of 5:1, and mixed evenly using an electric stirrer at a speed of 300 rpm and a stirring time of 12 min to obtain a mixed slurry in a non-fluid state. Finally, the mixed slurry is mixed and stirred with a PCS precursor at a mass ratio of 11:9 to prepare a mixed coating slurry.

[0056] b. Preparation of SiC prefabricated cloth: Use a ruler to measure the size of 300mm×200mm fiber cloth on the 2D SiC fiber cloth, and use a knife to cut it according to the size. A total of 9 sheets are cut, and they are soaked in anhydrous ethanol for ultrasonic cleaning. After removing surface impurities and drying, they are aligned and stacked. Use a graphite splint to fix the arranged SiC fiber cloth, and use graphite bolts to fix it around to ensure the flatness of the SiC fiber cloth; then use the CVI process to deposit the BN interface, and the precursor gas source used is boron trichloride (BCl 3 ) and ammonia (NH 3 ), where BCl 3 As the boron source, NH 3 The nitrogen source is argon (Ar), the carrier gas is argon (Ar), and the diluent gas is hydrogen (H 2 ), the gas flow rates were 25 ml / min, 65 ml / min, 110 ml / min, 110 ml / min, the deposition time was 210 h, the deposition temperature was 750 ° C, and the thickness was about 475 nm; then the CVI process was also used to deposit Si 3 N 4 The protective layer, the precursor gas source used is silicon tetrachloride (SiCl 4 ) and ammonia (NH 3 ), where SiCl 4 As silicon source, NH 3 The nitrogen source is argon (Ar), the carrier gas is argon (Ar), and the diluent gas is hydrogen (H 2 ), the gas flow rates were 105 ml / min, 65 ml / min, 110 ml / min, 110 ml / min respectively, the deposition time was 170 h, the deposition temperature was 900 ° C, and the thickness was about 3.5 μm.

[0057] c.Si 3 N 4 Preparation of the substrate: The mixed coating slurry prepared in step a is evenly applied to the surface of the SiC fiber prefabricated cloth prepared in step b with a brush, and then multiple layers of prefabricated cloth coated with the slurry are stacked and fixed with a graphite clamp, and finally SiC fiber prefabricated cloth is processed by CVI process. 3 N 4 The matrix is ​​densified, and the precursor gas source used is silicon tetrachloride (SiCl 4 ) and ammonia (NH 3 ), where SiCl 4 As silicon source, NH 3 The nitrogen source is argon (Ar), the carrier gas is argon (Ar), and the diluent gas is hydrogen (H 2 ), the gas flow rates are 105ml / min, 65ml / min, 110ml / min, 110ml / min respectively, and the deposition temperature is 900℃.

[0058] Embodiment 3:

[0059] In this embodiment, the SiC prepared by the coating layer method f / Si 3 N 4 -WB 4 C-Sm 2 O 3 The SiC composite material contained 60 wt% polycarbosilane (PCS) and had a thickness of 2.77 mm.

[0060] a. Preparation of mixed coating slurry: W powder, B 4 C powder and Sm 2 O 3 After the powders are mixed in a volume fraction ratio of 6:3:1, the mixed powders are placed in a ball mill and ball milled for 24 hours at a ball-to-material ratio of 9:1 to form a mixed powder. Then, the evenly mixed powders are ground and sieved to obtain a filler powder mixture. The filler powder mixture and the solution carrier (water and xylene) are placed in a beaker in a mass ratio of 6:1, and mixed evenly with an electric stirrer at a speed of 400 rpm and a stirring time of 15 minutes to obtain a mixed slurry in a non-fluid state. Finally, the mixed slurry is mixed and stirred with a PCS precursor in a mass ratio of 3:2 to prepare a mixed coating slurry.

[0061] b. Preparation of SiC prefabricated cloth: Use a ruler to measure the size of 300mm×200mm fiber cloth on the 2D SiC fiber cloth, and use a knife to cut it according to the size. A total of 10 sheets are cut, and they are soaked in anhydrous ethanol for ultrasonic cleaning. After removing surface impurities and drying, they are aligned and stacked. Use a graphite splint to fix the arranged SiC fiber cloth, and use graphite bolts to fix it around to ensure the flatness of the SiC fiber cloth; then use the CVI process to deposit the BN interface, and the precursor gas source used is boron trichloride (BCl 3 ) and ammonia (NH 3 ), where BCl 3 As the boron source, NH 3 The nitrogen source is argon (Ar), the carrier gas is argon (Ar), and the diluent gas is hydrogen (H 2 ), the gas flow rates were 30 ml / min, 70 ml / min, 120 ml / min, 120 ml / min, the deposition time was 260 h, the deposition temperature was 850 ° C, and the thickness was about 500 nm; then the CVI process was also used to deposit Si 3 N 4 The protective layer, the precursor gas source used is silicon tetrachloride (SiCl 4 ) and ammonia (NH 3 ), where SiCl 4 As silicon source, NH 3The nitrogen source is argon (Ar), the carrier gas is argon (Ar), and the dilution gas is hydrogen (H 2 ), the gas flow rates were 110 ml / min, 70 ml / min, 120 ml / min, 120 ml / min, respectively; the deposition time was 220 h; the deposition temperature was 1000 °C; and the thickness was about 4.5 μm.

[0062] c.Si 3 N 4 Preparation of the substrate: The mixed coating slurry prepared in step a is evenly applied to the surface of the SiC fiber prefabricated cloth prepared in step b with a brush, and then multiple layers of prefabricated cloth coated with the slurry are stacked and fixed with a graphite clamp, and finally SiC fiber prefabricated cloth is processed by CVI process. 3 N 4 The matrix is ​​densified, and the precursor gas source used is silicon tetrachloride (SiCl 4 ) and ammonia (NH 3 ), where SiCl 4 As silicon source, NH 3 The nitrogen source is argon (Ar), the carrier gas is argon (Ar), and the dilution gas is hydrogen (H 2 ), the gas flow rates are 110ml / min, 70ml / min, 120ml / min, 120ml / min respectively, and the deposition temperature is 1000℃.

[0063] With reference to Examples 1 to 3 of the present invention, other components, proportions and specific preparation process parameters can be selected according to actual needs, and the technical effects described in the present invention can all be achieved. Therefore, the present invention will no longer list and explain them one by one.

[0064] According to the embodiments 1 to 3 of the present invention and the accompanying drawings, it can be seen that the beneficial effects of the present invention are:

[0065] Figure 2 .SiC f / Si 3 N 4 -WB 4 C-Sm 2 O 3 -SEM image of the internal microstructure of SiC composite material and EDS energy spectrum scanning results: (a) morphology distribution characteristics of each component at low magnification, (b) matrix structure characteristics, (c) fiber bundle morphology characteristics, it can be seen that the outer side of the fiber bundle and the outer structure are intact, (d) morphology of each component of a single fiber.

[0066] Overall, the composite material consists of the gray area as SiC fiber bundles and the WB between the fiber bundles. 4 C-Sm 2 O 3 -SiC(WBSP) functional phase. f / Si3 N 4 -WBS composites compared to SiC f / Si 3 N 4 - The pore distribution of WBSP composite materials is more uniform, the pore size is more uniform, and it is mainly closed small and medium-sized pores, which are significantly smaller than SiC f / Si 3 N 4 -WBS composite materials also have intra-bundle pores in the fiber bundles due to the "bottleneck effect" of the CVI process. 3 N 4 The matrix phase boundary is clear, no reaction occurs, and no SiC appears. f / Si 3 N 4 -The white Sm-Si-ON glass phase appears in the WBS composite material. This shows that the addition of PCS in the functional filler effectively improves the compatibility of the functional filler with the Si3N4 matrix and inhibits the formation of the Sm-Si-ON glass phase. The interface phases in all fiber bundles are intact, and no penetration and erosion of the glass phase on the interface is found. SiC f / Si 3 N 4 -WBSP composite materials did not form areas enriched with white glass phase around the holes and at the outer edge of the fiber bundle. The fibers, interfaces and protective layer matrix at the outer edge of the fiber bundle maintained almost complete morphology, and the three were closely fitted. In addition, discontinuities were observed in the WBSP phase, and the discontinuities were Si 3 N 4 This may be because Si 3 N 4 During the substrate deposition process, PCS pyrolysis at high temperature causes volume shrinkage, which leads to the shrinkage of the WBSP phase as a whole and the generation of a large number of cracks. These cracks are formed by the deposited Si 3 N 4 The matrix is ​​filled to form a discontinuity.

[0067] Figure 3 .SiC f / Si 3 N 4 -WB 4 C-Sm 2 O 3 -SiC composite materials and SiC f / Si 3 N 4 -WB 4 C-Sm 2 O 3 Comparison of radiation shielding properties of composite materials under 241Am and 137Cs radiation sources: Shielding effectiveness.

[0068] For low energy photons, SiCf / Si3N4-WBS and SiC f / Si 3 N 4 -WBSP composite materials require material thicknesses of 0.47cm and 0.84cm to achieve a 70% shielding rate, and 0.91cm and 1.60cm to achieve a 90% shielding rate. It can be seen that SiC f / Si 3 N 4 -WBS and SiC f / Si 3 N 4 -WBSP composite materials require a gradually increasing gap in material thickness, but for shielding low-energy photons, both types of composite materials require a smaller thickness; in the higher energy range, SiC f / Si 3 N 4 -WBSP composites have slightly weaker radiation shielding performance than SiC f / Si 3 N 4 -WBS, but with the increase of thickness, the two materials gradually tend to the same shielding efficiency. f / Si 3 N 4 -After WBS composite material is optimized, the SiC f / Si 3 N 4 -WBSP composite materials do not show significant performance degradation in shielding relatively high-energy photons, SiC f / Si 3 N 4 -WBSP composite materials have much better mechanical properties than SiC while ensuring radiation shielding performance f / Si 3 N 4 -WBS composite materials.

[0069] Figure 4 .SiC f / Si 3 N 4 -W-B4C-Sm 2 O 3 -Load-displacement curves and fracture SEM morphology of SiC composite materials at high temperatures: (i), (ii) and (iii) are the fracture surfaces of the materials at 1100℃, 1200℃ and 1350℃ respectively (low magnification).

[0070] Figure 4 Is SiC f / Si 3 N 4 -WBSP composite materials were subjected to high temperature bending tests at different temperatures. As the test temperature increased, SiC f / Si 3 N 4 The flexural strength of the -WBSP composite material continued to decrease, and the flexural strengths at 800℃, 1100℃ and 1350℃ were 313.86MPa, 256.39MPa and 203.04MPa, respectively, which were 15.18%, 30.71% and 45.13% lower than the room temperature strength. f / Si 3 N 4 -WBS composite materials compared to SiC at different temperatures f / Si 3 N 4 -The mechanical properties of WBSP composite materials have been significantly improved. At a high temperature of 1350°C, the flexural strength of the material is still above 200MPa, even greater than that of SiC f / Si 3 N 4 -Bending strength of WBS composite material at room temperature. Compared with SiC f / Si 3 N 4 -The fracture mode of WBS composite material at high temperature obviously changes to brittle fracture, SiC f / Si 3 N 4 The fracture mode of the WBSP composite material at 800℃ and 1100℃ is still pseudo-plastic fracture, and the fracture work is greater than the test results at room temperature, indicating that the toughness of the material is improved to a certain extent at high temperature. When the temperature reaches 1350℃, the material exhibits a brittle fracture mode, but at this time the material still has a high fracture work. And as the temperature increases, the displacement at which the load reaches the maximum value gradually increases, which is similar to the SiC f / Si 3 N 4 -WBS composites compared to SiC f / Si 3 N 4 -The toughness and strength of WBSP composite materials become more obvious as the temperature increases.

Claims

1. A method for preparing a high temperature resistant, radiation resistant and stealth multifunctional integrated ceramic matrix composite material, characterized in that Here are the steps: Step 1: Using CVI process to deposit boron nitride BN interface and silicon nitride Si3N4 protective layer on multiple SiC fiber cloths in sequence; The precursor gas sources for depositing the boron nitride BN interface are 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 diluent gas is hydrogen H2; When depositing the silicon nitride Si3N4 protective layer, the precursor gas sources are silicon tetrachloride SiCl4 and ammonia NH3, wherein SiCl4 is the silicon source, NH3 is the nitrogen source, the carrier gas is argon Ar, and the diluent gas is hydrogen H2; Step 2: applying the mixed coating slurry on the surface of each SiC prefabricated cloth deposited in step 1, and then stacking and fixing multiple SiC prefabricated cloths; The mixed coating slurry is prepared by mixing a mixed powder of 50% to 60% by volume of W powder, 20% to 30% of B4C powder and 10% to 20% of Sm2O3 powder with ultrapure water, and then adding polycarbosilane PCS; The added polycarbosilane PCS is 50-60wt%; (relative to which percentage?) Step 3: Using CVI process to deposit Si3N4 matrix to densify SiC prefabricated fabric, to obtain high temperature resistant, radiation resistant and stealth multifunctional integrated ceramic matrix composite material; When the CVI process is used to deposit a Si3N4 substrate, the precursor gas sources are 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 diluent gas is hydrogen H2.

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

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

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

5. The method for preparing the high temperature resistant, radiation resistant and stealth multifunctional 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 to 220 hours, and the deposition temperature is 800 to 1000°C; the gas flow ratio is: silicon source SiCl4 is 100 to 110 ml / min, nitrogen source NH3 is 60 to 70 ml / min, carrier gas argon Ar is 100 to 120 ml / min, and dilution gas hydrogen H2 is 100 to 120 ml / min.

6. The method for preparing the high temperature resistant, radiation resistant and stealth multifunctional integrated ceramic matrix composite material according to claim 1, characterized in that: When the CVI process in step 3 densifies the substrate, the deposition temperature is 800-1000°C; 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 multifunctional integrated ceramic matrix composite material according to claim 1, characterized in that: The mixed powder of the W powder, B4C powder and Sm2O3 powder is prepared by ball milling process, with a ball-to-material ratio of 7:1 to 9:1 and a ball milling time of 24 hours.

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

1.

9. A high temperature resistant, radiation resistant and stealth multifunctional integrated ceramic matrix composite material prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The structure of the multifunctional integrated ceramic matrix composite is SiC f / Si3N4-W-B4C-Sm2O3-SiC, comprising SiC fiber cloth, a boron nitride BN interface with a thickness of 450-500 nm on the SiC fiber cloth; a silicon nitride Si3N4 with a thickness of 2.5-4.5 μm on the BN interface; WBS functional component particles and polycarbosilane PCS functional component particles are arranged on the SiC fiber cloth to form a WBSP (W-B4C-Sm2O3-PCS) functional filling material; the overall structure is obtained by dense deposition by a CVI process; the SiC f / Si3N4-WBSP composite material densification degree is not less than 85%; SiC f The linear attenuation coefficient and mass attenuation coefficient of the / Si3N4-WBSP composite material are 0.242 cm -1 and 0.103cm 2 / g; shielding effect is over 70%; RL value can reach full-frequency absorption below -9dB, electromagnetic wave absorption rate is about over 87%, and effective absorption bandwidth is 3.52GHz.

10. An application of the high temperature resistant, radiation resistant and stealth multifunctional integrated ceramic matrix composite material according to claim 9, characterized in that: It is used in high temperature irradiation complex environment with temperature up to 1350℃, radiation source energy and electromagnetic wave frequency of 0.662MeV and 12.4GHz respectively; at the same time, it maintains good shielding performance and stealth performance. Under room temperature conditions, the shielding effect and electromagnetic wave absorption rate can reach more than 70% and 87% respectively; when the ambient temperature is 1350℃, SiC f The shielding effect and electromagnetic wave absorptivity of the Si3N4-WBSP composite material decreased to 54% and over 85% respectively.

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