Modified ceramic fiber aerogel composite material and preparation method thereof
By growing silicon carbide nanowire modified oxide fiber sponge in situ, a multi-scale double fiber network structure is constructed, which solves the complex problem of ceramic fiber aerogel enhancement method, and achieves the synchronous improvement of lightweight, heat insulation, high temperature resistance and electromagnetic wave absorption performance.
Patent Information
- Application Number
- CN202510456354.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-11
- Publication Date
- 2025-07-18
AI Technical Summary
The existing ceramic fiber aerogel has complex processes and cannot simultaneously improve its mechanical properties, thermal insulation properties and electromagnetic wave absorption properties.
By growing silicon carbide nanowire modified oxide fiber sponge in situ, a multi-scale double fiber network structure is constructed, and modified ceramic fiber aerogel composites are prepared by combining sol gel and atmospheric drying process.
It achieves synchronous improvements in lightweight, heat insulation, high temperature resistance and good electromagnetic wave absorption performance, and the material has excellent mechanical properties and dielectric loss capabilities.
Smart Images
Figure CN120329062A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of ceramic fiber aerogels, and particularly relates to a modified ceramic fiber aerogel composite material and a preparation method thereof. Background Art
[0002] With the rapid development of new detection and remote control technologies, the survival and penetration capabilities of high-value targets such as advanced aircraft are increasingly threatened. Therefore, there is a broad prospect for developing protective materials with both lightweight heat insulation and electromagnetic wave absorption functions. Fiber aerogels have the advantages of light weight, low thermal conductivity, and high thermal stability, and are widely used in the field of thermal protection. However, the low strength of single ceramic fiber aerogels severely limits their applications under dynamic and impact conditions, so they need to be strengthened.
[0003] In the prior art, for the fiber-reinforced structure of ceramic fiber aerogels, the main raw materials focus on short-cut fibers or binders at the micron scale. Generally, it is necessary to pre-treat the fibers in advance or through complex processes to realize the preparation of three-dimensional structures. These methods have the problems of complex processes and high costs, and cannot simultaneously improve the mechanical properties, heat insulation properties, and electromagnetic wave absorption properties of ceramic fiber aerogels.
[0004] Based on this, there is an urgent need to provide a modified ceramic fiber aerogel composite material and a preparation method thereof. Summary of the Invention
[0005] The embodiments of the present invention provide a modified ceramic fiber aerogel composite material and a preparation method thereof, which can solve the problems that the preparation process of the traditional strengthening method of ceramic fiber aerogels is complex and cannot simultaneously improve the mechanical properties, heat insulation properties, and electromagnetic wave absorption properties of ceramic aerogels.
[0006] In the first aspect, the present invention provides a preparation method of a modified ceramic fiber aerogel composite material, and the preparation method includes the following steps:
[0007] (1) Perform high-temperature heat treatment on an oxide fiber sponge and a modified mixed powder in an inert gas atmosphere to obtain a modified oxide fiber sponge; wherein, the oxide fiber sponge is impregnated with a catalyst solution;
[0008] (2) Stir and mix a siloxane-based precursor, a mixed solvent, and ammonia water to obtain a sol precursor solution;
[0009] (3) Immerse the modified oxide fiber sponge in the sol precursor solution, and after sol-gel, drying, and high-temperature heat treatment in sequence, obtain the modified oxide fiber sponge-reinforced ceramic aerogel composite material.
[0010] Preferably, in step (1), the oxide fiber sponge is obtained by spinning alumina fibers and silica fibers.
[0011] Preferably, the oxide fiber sponge has a layered structure, and the diameters of the alumina fibers and silica fibers are 500 - 1000 nm.
[0012] Preferably, in step (1), the silicon source powder is polycarbosilane, methyl silicone resin, or a mixture of silicon dioxide and silicon powder, and the carbon source powder is phenolic resin or epoxy resin.
[0013] Preferably, in step (1), the solute of the catalyst solution is at least one of ferrocene, iron nitrate, or iron acetylacetonate, and the solvent is at least one of xylene, n - hexane, ethanol, or N,N - dimethylformamide.
[0014] More preferably, the mass concentration of the catalyst solution is 1 - 5%.
[0015] Preferably, in step (2), the siloxane precursor is two of methyltrimethoxysilane, dimethyldimethoxysilane, or vinyltrimethoxysilane.
[0016] Preferably, in step (2), the mixed solvent is composed of water and ethanol. Among them, the mass ratio of the siloxane precursor, water, and ethanol is 5:1:(6 - 10), and the mass ratio of ammonia water to the total mass of the siloxane precursor, water, and ethanol is 1:(4 - 6).
[0017] Preferably, in step (3), the temperature of the sol - gel is 60 - 90 °C, and the time is - 1 - 3 h. Preferably, in step (3), the temperature of the drying is 80 - 100 °C, and the time is 3 - 6 h.
[0018] Preferably, in steps (1) and (3), the temperature of the high - temperature heat treatment is 900 - 1200 °C, and the time is 20 - 60 min.
[0019] In a second aspect, the present invention also provides a modified ceramic fiber aerogel composite material, which is prepared by using the preparation method described in any one of the first aspects above.
[0020] The present invention has at least the following beneficial effects compared with the prior art:
[0021] In the present invention, first, the oxide fiber sponge is modified by in-situ growth of silicon carbide nanowires to construct a multi-scale dual-fiber network structure, thereby endowing the oxide fiber sponge with a more complex fiber pore distribution and a strong and tough skeleton structure. Then, the modified oxide fiber sponge is immersed in a sol precursor solution, and the aerogel is compounded by the gelation of the sol precursor solution and atmospheric drying. During the high-temperature heat treatment process, the aerogel particles can form chemical bonding points between the fibers of the oxide fiber sponge to obtain a modified ceramic fiber aerogel composite material. In this way, the lightweight and low-thermal-conductivity nanowires and aerogel particles are introduced into the oxide fiber sponge as reinforcing phases. The interpenetrating network and the bonding points of the aerogel particles can significantly improve the soft elastic structure of the oxide fiber sponge, especially in the direction perpendicular to the layered structure, which can greatly improve the mechanical properties of the oxide fiber sponge. Moreover, the chemically modified oxide fiber sponge has good dielectric loss ability. At the same time, the ultra-low density and low thermal conductivity of the oxide fiber sponge contribute to further reducing its thermal conductivity on the basis of maintaining the lightweight characteristics of the composite material, so that the final composite material not only has the properties of lightweight, heat insulation and high temperature resistance, but also has good electromagnetic wave absorption performance. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.
[0023] Figure 1 It is a SEM image of the microstructure of the preparation process of the modified ceramic fiber aerogel composite material provided in Embodiment 1 of the present invention; wherein, (a) is the oxide nanofiber sponge, (b) is the modified oxide fiber sponge, and (c) is the modified ceramic fiber aerogel composite material;
[0024] Figure 2 It is a longitudinal compressive stress-strain curve of a modified ceramic fiber aerogel composite material provided in Embodiment 1 of the present invention; wherein, the abscissa is the elongation rate and the ordinate is the compressive stress;
[0025] Figure 3 It is an electromagnetic wave reflection loss diagram of a modified ceramic fiber aerogel composite material provided in Embodiment 1 of the present invention; wherein, the abscissa is the frequency and the ordinate is the echo loss;
[0026] Figure 4 It is a thermal conductivity diagram of a modified ceramic fiber aerogel composite material provided in Embodiment 1 of the present invention at different temperatures; wherein, the abscissa is the temperature and the ordinate is the thermal conductivity. Detailed implementation manners
[0027] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0028] The low strength of the fibrous aerogel makes it extremely easy to deform, unable to meet the application requirements in multiple scenarios. Enhancing it through a fibrous structure is an effective method. In the prior art, micron-scale short-cut fibers or binders are usually used for enhancement, but this method has disadvantages such as complex processes or increased thermal conductivity. In addition, with the rapid development of detection technologies and high-speed aircraft, thermoprotective materials with multiple functions have become increasingly important, and it is of great significance to develop composite materials with lightweight, heat insulation and wave absorption functions.
[0029] Therefore, based on the above problems, the embodiments of the present invention provide a preparation method of a modified ceramic fiber aerogel composite material, and the preparation method includes the following steps:
[0030] (1) Perform high-temperature heat treatment on the oxide fiber sponge and the modified mixed powder in an inert gas atmosphere to obtain a modified oxide fiber sponge; wherein, the catalyst solution is impregnated on the oxide fiber sponge;
[0031] (2) Stir and mix the siloxane precursor, the mixed solvent and ammonia water to obtain a sol precursor solution;
[0032] (3) Immerse the modified oxide fiber sponge in the sol precursor solution, and obtain the modified ceramic fiber aerogel composite material after sol-gel, drying and high-temperature heat treatment in sequence.
[0033] In the embodiments of the present invention, first, the oxide fiber sponge is modified by in-situ growth of silicon carbide nanowires to construct a multi-scale dual-fiber network structure, thereby endowing the oxide fiber sponge with a more complex fiber pore distribution and a strong and tough skeleton structure. Then, the modified oxide fiber sponge is immersed in a sol precursor solution, and the aerogel is compounded by the gelation of the sol precursor solution and atmospheric drying. During the high-temperature heat treatment process, the aerogel particles can form chemical bonding points between the fibers of the oxide fiber sponge to obtain a modified ceramic fiber aerogel composite material. In this way, the light and low-thermal-conductivity nanowires and aerogel particles are introduced into the oxide fiber sponge as reinforcement phases, and the interpenetrating network and the bonding points of the aerogel particles can significantly improve the soft elastic structure of the oxide fiber sponge, especially greatly improving the mechanical properties of the oxide fiber sponge in the direction perpendicular to the layered structure. Moreover, the chemically modified oxide fiber sponge has good dielectric loss ability. At the same time, the ultra-low density and low thermal conductivity of the oxide fiber sponge contribute to further reducing its thermal conductivity on the basis of maintaining the light weight characteristics of the composite material, so that the final composite material not only has the properties of light weight, heat insulation and high temperature resistance, but also has good electromagnetic wave absorption performance.
[0034] According to some preferred embodiments, in step (1), the oxide fiber sponge is obtained by spinning alumina fibers and silica fibers.
[0035] According to some preferred embodiments, the oxide fiber sponge has a layered structure, and the diameters of the alumina fibers and silica fibers are 500 - 1000 nm (for example, it can be 500 nm, 600 nm, 700 nm, 800 nm, 900 nm or 1000 nm).
[0036] In the embodiments of the present invention, the oxide fiber sponge composed of alumina fibers and silica fibers has excellent high-temperature resistance, heat insulation performance and resilience performance, and the oxide fiber sponge formed by the two has a stable three-dimensional layered structure. The oxide fiber sponge composed of micron-scale alumina fibers and silica fibers (referred to as oxide micron fiber sponge) and the oxide fiber sponge composed of nano-scale alumina fibers and silica fibers (referred to as oxide nano fiber sponge) are compounded with the aerogel. The three-dimensional network skeleton of the oxide fiber sponge provides mechanical support, and the nano-pore structure of the aerogel fills the skeleton gaps, thereby forming a multi-functional composite material with both rigidity and flexibility. Further, it is found in the embodiments of the present invention that compared with the oxide micron fiber sponge, after the oxide nano fiber sponge is compounded with the aerogel, the brittle structure of the aerogel composite material can be significantly improved, and at the same time, its thermal conductivity can be further reduced on the basis of maintaining the light weight characteristics of the aerogel composite material.
[0037] It should be noted that in the embodiments of the present invention, the specific ratio of alumina fiber and silica fiber is not specifically limited. At the same time, the oxide fiber sponge (oxide nanofiber sponge) can be prepared by the preparation method in Patent CN 116143506 A.
[0038] According to some preferred embodiments, in step (1), the modified mixed powder is composed of a silicon source powder and a carbon source powder; wherein, the silicon source powder is polycarbosilane, methyl silicone resin, or a mixture of silica and silicon powder, and the carbon source powder is phenolic resin or epoxy resin.
[0039] In the embodiments of the present invention, selecting the above-mentioned types of silicon source powder and carbon source powder is beneficial to the controllable and in-situ uniform growth of silicon carbide nanowires on the oxide fiber sponge, thereby significantly improving the mechanical strength of the oxide fiber sponge and preventing its structure from collapsing under high pressure or deformation. Moreover, the multi-scale dual-fiber network structure can endow the oxide fiber sponge with a more complex fiber pore distribution and a tough skeleton structure. At the same time, the dielectric loss characteristics of the silicon carbide nanowires are combined with the porous structure of the oxide fiber sponge, so as to endow the composite material with good electromagnetic wave absorption performance.
[0040] According to some preferred embodiments, in step (1), the solute of the catalyst solution is at least one of ferrocene, iron nitrate, or iron acetylacetonate, and the solvent is at least one of xylene, n-hexane, ethanol, or N,N-dimethylformamide; the mass concentration of the catalyst solution is 1-5% (for example, it can be 1%, 2%, 3%, 4%, or 5%).
[0041] In the embodiments of the present invention, first, the above-mentioned types of catalyst solution are prepared, and then the oxide fiber sponge is immersed in the catalyst solution. After impregnation for a period of time, it is placed in an oven for drying. By controlling the mass concentration of the catalyst solution, the catalyst solution is uniformly impregnated on the surface of the oxide fiber sponge, which is beneficial to catalyze the subsequent reaction of the silicon source powder and the carbon source powder and uniformly form silicon carbide nanowires with controllable morphology on the surface of the oxide fiber sponge. It has been confirmed by experiments in the embodiments of the present invention that if the concentration of the catalyst solution is too low, the growth density of the silicon carbide nanowires will be low, which is not conducive to significantly improving the mechanical strength of the oxide fiber sponge. If the concentration of the catalyst solution is too high, the size of the silicon carbide nanowires will be small, and even the silicon carbide nanowires will form a non-uniform agglomerated structure, which will have an adverse effect on the performance of the oxide fiber sponge.
[0042] According to some preferred embodiments, in step (2), the siloxane precursor is two of methyltrimethoxysilane, dimethyldimethoxysilane, or vinyltrimethoxysilane.
[0043] According to some preferred embodiments, in step (2), the mixed solvent is composed of water and ethanol. Among them, the mass ratio of the siloxane precursor, water and ethanol is 5:1:(6 - 10) (for example, it can be 5:1:6, 5:1:7, 5:1:8, 5:1:9 or 5:1:10), and the mass ratio of ammonia water to the total mass of the siloxane precursor, water and ethanol is (4 - 6):1 (for example, it can be 4:1, 5:1 or 6:1).
[0044] In the embodiments of the present invention, after mixing the above-mentioned types of siloxane precursors, water and ethanol in proportion, ammonia water is added, and after stirring for a period of time, a sol precursor solution is obtained. Then, the modified oxide fiber sponge is completely immersed in the above sol precursor solution, so that a silicon oxycarbide aerogel is in-situ formed on the surface of the oxide fiber sponge. By reasonably regulating the proportions of each component in the sol precursor solution, the oxide fiber sponge and the silicon oxycarbide aerogel can be fully compounded. The modified silicon carbide nanowires in the oxide fiber sponge and the silicon oxycarbide aerogel can jointly endow the composite material with excellent dielectric loss ability, and the oxide fiber sponge can significantly improve the brittle structure of the aerogel composite material, so that a modified ceramic fiber aerogel composite material with both light weight, excellent heat insulation performance and high temperature resistance can be obtained.
[0045] Meanwhile, it should be noted that in the embodiments of the present invention, the siloxane precursor can specifically be methyltrimethoxysilane and dimethyldimethoxysilane with a mass ratio of (3 - 5):1, methyltrimethoxysilane and vinyltrimethoxysilane with a mass ratio of (3 - 5):1, or dimethyldimethoxysilane and vinyltrimethoxysilane with a mass ratio of (3 - 5):1.
[0046] According to some preferred embodiments, in step (3), the temperature of the sol-gel is 60 - 90 °C (for example, it can be 60 °C, 70 °C, 80 °C or 90 °C), and the time is 1 - 3 h (for example, it can be 1 h, 2 h or 3 h); the temperature of the drying is 80 - 100 °C (for example, it can be 80 °C, 90 °C or 100 °C), and the time is 3 - 6 h (for example, it can be 3 h, 4 h, 5 h or 6 h).
[0047] In the embodiments of the present invention, the modified oxide fiber sponge is immersed in the sol precursor solution for impregnation, then placed in a mold and subjected to sol-gel in an oven. After that, the residual solvent in the obtained wet gel is replaced with ethanol, and then dried at the above temperature. By reasonably controlling the temperature in the sol-gel process and the temperature in the atmospheric drying process, it is beneficial to obtain a silicon oxycarbide aerogel with a dense gel network, good mechanical strength and good porosity without affecting the structure of the oxide fiber sponge.
[0048] According to some preferred embodiments, in steps (1) and (3), the temperature of the high-temperature heat treatment is 900 to 1200 °C (for example, it can be 900 °C, 1000 °C, 1100 °C or 1200 °C), and the time is 20 to 60 min (for example, it can be 20 min, 30 min, 40 min, 50 min or 60 min).
[0049] In the embodiment of the present invention, in step (1), the oxide fiber sponge is subjected to high-temperature heat treatment with a silicon source powder and a carbon source powder under an inert gas, so that the silicon source and the carbon source can react and form silicon carbide nanowires on the surface of the oxide fiber sponge by chemical vapor deposition to realize the modification of the oxide fiber sponge; in step (3), the composite material formed by the modified oxide fiber sponge and the silicon oxycarbide aerogel is further subjected to high-temperature heat treatment under an inert gas, so that the modified oxide fiber sponge and the silicon oxycarbide aerogel can be better combined by chemical bonding, and it is beneficial to remove impurities, so that the modified ceramic fiber aerogel composite material has the characteristics of light weight, high strength, high temperature resistance (temperature resistance above 800 °C), high structural stability and high wave absorption performance.
[0050] The embodiment of the present invention also provides a modified ceramic fiber aerogel composite material prepared by using the preparation method described in any one of the above.
[0051] In summary, the preparation method in the embodiment of the present invention has the advantages of low cost, simple process and short process. Through the in-situ growth of silicon carbide nanowires, a modified three-dimensional oxide fiber sponge structure-reinforced ceramic aerogel composite material can be prepared by the sol-gel and atmospheric pressure drying processes. Moreover, the modified ceramic fiber aerogel composite material prepared by this method not only has light weight, excellent heat insulation performance and mechanical properties, but also has good electromagnetic wave absorption performance in the X-band, thus endowing the composite material with multifunctionality.
[0052] In order to more clearly illustrate the technical solutions and advantages of the present invention, a modified ceramic fiber aerogel composite material and its preparation method will be described in detail through several embodiments below.
[0053] Example 1:
[0054] (1) Add the catalyst (ferrocene) to ethanol and stir at a speed of 400 r / min at 25 °C for 1 h, then mix evenly to obtain a catalyst solution with a mass concentration of 3%; Immerse the oxide fiber sponge (a ceramic nanofiber sponge composed of alumina and silica fibers with diameters of 500 - 1000 nm) in the catalyst solution, take it out after impregnation for 30 min, and dry it in an oven at 70 °C for 1 h; Then place the dried oxide fiber sponge in a covered porcelain boat and place it in a tube furnace. A mixed powder material of a silicon source powder (methyl silicone resin) and a carbon source powder (polysilcarbosilane) is placed at the bottom of the porcelain boat. Perform high-temperature treatment at 1200 °C for 30 min in a nitrogen atmosphere to obtain a modified oxide fiber sponge;
[0055] (2) Mix the siloxane precursor (methyltrimethoxysilane and dimethyldimethoxysilane with a mass ratio of 5:1), the mixed solvent (water and ethanol) in proportion and stir magnetically for 1 h, then add ammonia water and stir for 10 min to obtain a sol precursor solution; Among them, the mass ratio of the siloxane precursor, water and ethanol is 5:1:6; The mass ratio of ammonia water to the total mass of the siloxane precursor and the mixed solvent is 1:5;
[0056] (3) Immerse the modified oxide fiber sponge in the sol precursor solution for impregnation for 30 min, then put it into a mold and carry out sol-gel at 80 °C in an oven for 3 h. Then, replace the residual solvent in the obtained wet gel with ethanol, and dry it at 80 °C for 5 h. Finally, under a nitrogen atmosphere, heat it to 1200 °C at a rate of 5 °C / min for high-temperature heat treatment for 60 min to obtain a modified ceramic fiber aerogel composite material.
[0057] Example 2:
[0058] (1) Add the catalyst (iron nitrate) to ethanol and stir at a speed of 400 r / min at 25 °C for 1 h, then mix evenly to obtain a catalyst solution with a mass concentration of 5%; Immerse the oxide fiber sponge (a ceramic nanofiber sponge composed of alumina and silica fibers with diameters of 500 - 1000 nm) in the catalyst solution, take it out after impregnation for 30 min, and dry it in an oven at 70 °C for 1 h; Then place the dried oxide fiber sponge in a covered porcelain boat and place it in a tube furnace. A mixed powder material of a silicon source powder (polysilcarbosilane) and a carbon source powder (phenolic resin) is placed at the bottom of the porcelain boat. Perform high-temperature treatment at 1300 °C for 30 min in a nitrogen atmosphere to obtain a modified oxide fiber sponge;
[0059] (2) Mix the siloxane precursor (methyltrimethoxysilane and dimethyldimethoxysilane with a mass ratio of 4:1), the mixed solvent (water and ethanol) in proportion and perform electromagnetic stirring for 1 h, then add ammonia water and stir for 10 min to obtain a sol precursor solution; wherein, the mass ratio of the siloxane precursor, water and ethanol is 5:1:8; the mass ratio of ammonia water to the total mass of the siloxane precursor and the mixed solvent is 1:6;
[0060] (3) Immerse the modified oxide fiber sponge in the sol precursor solution for impregnation for 30 min, then put it into a mold and carry out sol-gel at 80 °C in an oven for 3 h. After that, replace the residual solvent in the obtained wet gel with ethanol, and then dry it at 80 °C for 6 h. Finally, under a nitrogen atmosphere, heat it to 1300 °C at a rate of 5 °C / min for high-temperature heat treatment for 60 min to obtain a modified ceramic fiber aerogel composite.
[0061] Example 3:
[0062] Example 3 is basically the same as Example 1, the difference is that: in step (1), the concentration of the catalyst solution is 7 wt%.
[0063] In this example, silicon carbide nanowires grow densely on the surface of the oxide fiber sponge, with a shorter length, and no more large aspect ratio nanowire networks are formed, resulting in a lower wave absorption performance and a lower compressive strength of the finally formed composite material.
[0064] Comparative Example 1:
[0065] Comparative Example 1 is basically the same as Example 1, the difference is that in step (1), the oxide fiber sponge is not modified, that is, the oxide fiber sponge is directly immersed in the sol precursor solution and then subjected to sol-gel, drying and high-temperature heat treatment in sequence to obtain a modified ceramic fiber aerogel composite.
[0066] Comparative Example 2:
[0067] (1) Mix the siloxane precursor (methyltrimethoxysilane and dimethyldimethoxysilane with a mass ratio of 5:1), the mixed solvent (water and ethanol) in proportion and perform electromagnetic stirring for 1 h, then add ammonia water and stir for 10 min to obtain a sol precursor solution; wherein, the mass ratio of the siloxane precursor, water and ethanol is 5:1:5; the mass ratio of ammonia water to the total mass of the siloxane precursor and the mixed solvent is 1:5;
[0068] (2) Immerse the fiber felt formed by alumina and silica in the sol precursor solution for 30 min, then put it into a mold and carry out sol-gel at 80 °C in an oven for 4 h. After that, displace the residual solvent in the obtained wet gel with ethanol, and then dry it at 80 °C for 12 h. Finally, under a nitrogen atmosphere, heat it to 1200 °C at a rate of 5 °C / min for high-temperature heat treatment for 60 min to obtain the modified ceramic fiber aerogel composite material.
[0069] Perform performance tests on the modified ceramic fiber aerogel composite materials (hereinafter referred to as samples) prepared in Examples 1 to 3 and Comparative Examples 1 to 2, and the test results are shown in Table 1.
[0070] Mechanical strength test: Use a universal testing machine to compress samples with a size of 10*10*10 mm at a speed of 0.5 mm / min; perform electromagnetic wave absorption performance test using the coaxial method; perform thermal conductivity test using the steady-state flat plate heat flux method.
[0071] Table 1
[0072]
[0073] Note: "-" indicates that the performance cannot be tested.
[0074] It can be seen from Figure 1 that compared with the unmodified oxide fiber sponge, silicon carbide nanowires grow in-situ on the surface of the modified oxide fiber sponge. These nanowires can form a multi-scale dual-fiber network structure with the oxide fiber sponge, thus endowing the oxide fiber sponge with a more complex fiber pore distribution and a tough skeleton structure. After compounding the modified oxide fiber sponge with the ceramic aerogel, the formed composite material can have richer pores and can significantly improve the brittle structure of the aerogel. Further, combining Figures 2 to 4 and comparing the data in Table 1, it can be found that the modified ceramic fiber aerogel composite materials prepared in the examples of the present invention have multifunctionality, not only having lightweight properties, excellent heat insulation properties and mechanical properties, but also having good electromagnetic wave absorption properties in the X band.
[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A preparation method of a modified ceramic fiber aerogel composite material, characterized in that, The preparation method comprises the following steps: (1) Subject the oxide fiber sponge and the modified mixed powder to high-temperature heat treatment in an inert gas atmosphere to obtain a modified oxide fiber sponge; wherein, the oxide fiber sponge is impregnated with a catalyst solution; (2) Stir and mix a siloxane-based precursor, a mixed solvent, and ammonia water to obtain a sol precursor solution; (3) Immerse the modified oxide fiber sponge in the sol precursor solution, and after sol-gel, drying, and high-temperature heat treatment in sequence, obtain the modified ceramic fiber aerogel composite material.
2. The preparation method according to claim 1, characterized in that, In step (1), the oxide fiber sponge is obtained by spinning alumina fibers and silica fibers.
3. The preparation method according to claim 2, characterized in that, The oxide fiber sponge has a layered structure, and the diameters of the alumina fibers and silica fibers are 500-1000 nm.
4. The preparation method according to claim 1, characterized in that, In step (1), the modified mixed powder is composed of a silicon source powder and a carbon source powder; wherein, the silicon source powder is polycarbosilane, methyl silicone resin, or a mixture of silicon dioxide and silicon powder, and the carbon source powder is phenolic resin or epoxy resin.
5. The preparation method according to claim 1, characterized in that In step (1), the solute of the catalyst solution is at least one of ferrocene, iron nitrate, or iron acetylacetonate, and the solvent is at least one of xylene, n-hexane, ethanol, or N,N-dimethylformamide; Preferably, the mass concentration of the catalyst solution is 1-5%.
6. The preparation method according to claim 1, characterized in that, In step (2), the siloxane-based precursor is two of methyltrimethoxysilane, dimethyldimethoxysilane, or vinyltrimethoxysilane.
7. The preparation method according to claim 6, characterized in that, In step (2), the mixed solvent is composed of water and ethanol, wherein, the mass ratio of the siloxane-based precursor, water, and ethanol is 5:1:(6-10), and the mass ratio of ammonia water to the total mass of the siloxane-based precursor and the mixed solvent is 1:(4-6).
8. The preparation method according to claim 1, characterized in that, In step (3), the temperature of the sol-gel is 60-90 °C, and the time is 1 h to 3 h; and / or The temperature of the drying is 80-100 °C, and the time is 3 h to 6 h.
9. The preparation method according to claim 1, characterized in that, In steps (1) and (3), the temperature of the high-temperature heat treatment is 900-1200 °C, and the time is 20-60 min.
10. A modified ceramic fiber aerogel composite material, characterized in that, Prepared by using the preparation method described in any one of claims 1 to 9.