A fiber-reinforced barium titanate-polymer-converted ceramic-based composite absorbing material and a preparation method thereof

Abstract

The present invention belongs to the field of absorbing materials, and in particular, relates to a fiber-reinforced barium titanate-polymer-converted ceramic-based composite absorbing material and a preparation method thereof. The composite absorbing material provided by the present invention includes a ceramic matrix and a fiber reinforcement embedded in the ceramic matrix; the ceramic matrix includes a barium titanate ceramic phase and a polymer-converted ceramic phase; the fiber reinforcement is composed of a plurality of layers of fiber cloth stacked together, and an interface layer is deposited on the surface of each layer of fiber cloth; the fibers in the plurality of layers of fiber cloth include a plurality of carbon fibers, silicon dioxide fibers, silicon carbide fibers, glass fibers, alumina fibers, and zirconium oxide fibers, and the interface layer is one or more of a PyC interface, a BN interface, and a SiC interface. The composite absorbing material provided by the present invention uses a plurality of fibers as reinforcements and a barium titanate-polymer-converted ceramic as a matrix, and has both excellent mechanical properties and absorbing properties.

Description

Technical Field

[0001] The invention belongs to the field of wave-absorbing materials, and in particular relates to a fiber-reinforced barium titanate-polymer-converted ceramic-based composite wave-absorbing material and a preparation method thereof. Background Art

[0002] As a high-performance absorbing material, polymer converted ceramics (PDCs) have become an important direction in the research of absorbing materials due to their excellent electromagnetic wave absorption and high temperature resistance. PDCs are obtained by high-temperature pyrolysis of organic polymer precursors. Their unique multiphase structure and crystal defects give them good electromagnetic wave absorption performance. However, single PDCs materials also have some limitations, mainly reflected in the difficulty in further improving the absorbing performance and poor mechanical properties. Summary of the invention

[0003] In view of this, the object of the present invention is to provide a fiber reinforced barium titanate-polymer converted ceramic-based composite absorbing material and a preparation method thereof. The composite absorbing material provided by the present invention has excellent mechanical properties and absorbing properties.

[0004] The present invention provides a fiber-reinforced barium titanate-polymer converted ceramic-based composite absorbing material, comprising a ceramic matrix and a fiber reinforcement embedded in the ceramic matrix;

[0005] The ceramic matrix includes a barium titanate ceramic phase and a polymer-converted ceramic phase distributed around the barium titanate ceramic phase;

[0006] The fiber reinforcement is composed of multiple layers of fiber cloth stacked together, and an interface layer is deposited on the surface of each layer of fiber cloth; the fibers in the multiple layers of fiber cloth include multiple types of carbon fiber, silica fiber, silicon carbide fiber, glass fiber, alumina fiber and zirconium oxide fiber, and the interface layer is one or more of a PyC interface, a BN interface and a SiC interface.

[0007] Preferably, the polymer-converted ceramic phase is a SiC ceramic phase, a Si3N4 ceramic phase, a SiCN ceramic phase or a SiBCN ceramic phase.

[0008] Preferably, the thickness of a single layer of the interface layer is 0.1-2 μm.

[0009] The present invention provides a method for preparing the fiber-reinforced barium titanate-polymer-converted ceramic-based composite absorbing material described in the above technical solution, comprising the following steps:

[0010] a) impregnating a fiber cloth having an interface layer deposited on the surface into a barium titanate ceramic slurry, and taking out and drying the fiber cloth after the impregnation is completed to obtain a fiber prepreg;

[0011] b) stacking the fiber prepreg sheets and then curing them under anaerobic conditions to obtain a fiber preform;

[0012] c) performing a binder removal treatment on the fiber preform under anaerobic conditions to obtain a fiber-reinforced barium titanate ceramic;

[0013] d) Impregnating the fiber-reinforced barium titanate ceramic into a polymer precursor, taking it out after the impregnation is completed and performing anaerobic thermal cracking to crack the impregnated polymer precursor into a ceramic phase, thereby obtaining a fiber-reinforced barium titanate-polymer conversion ceramic-based composite absorbing material.

[0014] Preferably, in step a), the components of the barium titanate ceramic slurry include BaTiO3 powder, a dispersant, a binder, a plasticizer and a solvent;

[0015] The particle size of the BaTiO3 powder is 0.1-5 μm; the dispersant is one or more of polyvinyl pyrrolidone, polyisobutylene and castor oil; the binder is one or more of polyethylene glycol, polyvinyl butyral, phenolic resin and polymethyl methacrylate; the plasticizer is one or more of methyl cellulose, dibutyl phthalate and polyvinyl acetate; the solvent is one or more of anhydrous ethanol, xylene, methanol and gasoline;

[0016] The dispersant accounts for 0.5-10wt% of the BaTiO3 powder; the binder accounts for 2-20wt% of the BaTiO3 powder; the plasticizer accounts for 2-30wt% of the BaTiO3 powder; and the solid content of the barium titanate ceramic slurry is 15-50vol%.

[0017] Preferably, in step a), the impregnation method is vacuum impregnation and / or vibration impregnation; the vacuum degree of the vacuum impregnation is -0.1~-0.3MPa, and the time is 2~12h; the frequency of the vibration impregnation is 40~120KHz, and the time is 0.5~12h; the drying temperature is 40~80℃, and the time is 120~900s.

[0018] Preferably, in step b), the oxygen-free condition is an argon and / or nitrogen atmosphere; the pressure of the curing treatment is 100-1200 kPa, the temperature is 120-200° C., and the time is 1-4 h.

[0019] Preferably, in step c), the anaerobic condition is a vacuum or an inert atmosphere; the heating rate of the debinding treatment is 1-10°C / min, the heating end temperature is 600-1200°C, and the holding time is 1-4h.

[0020] Preferably, in step d), the polymer precursor is polycarbosilane and / or polysilazane; the atmosphere of the oxygen-free thermal cracking is nitrogen and / or argon, the temperature is 800-1200° C., and the time is 0.5-6 h.

[0021] Preferably, the preparation method further comprises the following step: the product obtained in step d) is repeatedly subjected to step d) for multiple times.

[0022] Compared with the prior art, the present invention provides a fiber-reinforced barium titanate-polymer conversion ceramic-based composite absorbing material and a preparation method thereof. The composite absorbing material provided by the present invention includes a ceramic matrix and a fiber reinforcement embedded in the ceramic matrix; the ceramic matrix includes a barium titanate ceramic phase and a polymer conversion ceramic phase distributed around the barium titanate ceramic phase; the fiber reinforcement is composed of a plurality of layers of fiber cloth stacked together, and an interface layer is deposited on the surface of each layer of fiber cloth; the fibers in the plurality of layers of fiber cloth include a plurality of carbon fibers, silicon dioxide fibers, silicon carbide fibers, glass fibers, alumina fibers and zirconium oxide fibers, and the interface layer is one or more of a PyC interface, a BN interface and a SiC interface. The composite absorbing material provided by the present invention uses a plurality of fibers as reinforcements and a barium titanate-polymer conversion ceramic as a matrix, which improves the electromagnetic wave attenuation efficiency of the material while improving the mechanical properties of the material, thereby enabling the material to have both excellent mechanical properties and absorbing properties. More specifically, the present invention has at least the following beneficial effects:

[0023] (1) Improving wave absorption performance: By compounding barium titanate with polymer-converted ceramics and introducing fiber-reinforced materials, the electromagnetic wave absorption capacity of the composite material can be significantly improved, especially in the medium and high frequency bands, thereby improving stealth performance and meeting the needs of modern equipment for wave absorption and stealth.

[0024] (2) Improved mechanical properties: Fiber-reinforced materials improve the compression, bending and crack resistance of composite materials. The design of the fiber interface enhances the bonding force between the fiber and the matrix, and improves the stability and toughness of the material under high stress and high temperature environments.

[0025] (3) Enhanced high temperature and oxidation resistance: The polymer-converted ceramic matrix has excellent high temperature stability and oxidation resistance, which is suitable for high temperature environments in aerospace, ensuring that the material can still effectively absorb waves under extreme conditions.

[0026] (4) Simplified preparation process: multiple impregnation and cracking processes are used to ensure that the composite material is dense and uniform. The fiber interface deposition method effectively improves the material's microwave absorption performance and structural strength, making it easier to industrialize production.

[0027] (5) Broad application prospects: This composite material is suitable for aerospace and electronic equipment and other fields, helping to improve the equipment's stealth, anti-interference and survivability in harsh environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0029] Figure 1 This is a fracture microstructure morphology diagram of the composite material provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The invention provides a fiber-reinforced barium titanate-polymer converted ceramic-based composite wave-absorbing material, comprising a ceramic matrix and a fiber reinforcement embedded in the ceramic matrix.

[0032] In the composite absorbing material provided by the present invention, the ceramic matrix includes a barium titanate ceramic phase and a polymer-converted ceramic phase distributed around the barium titanate ceramic phase, and the two constitute an absorbing / transmitting network; the polymer-converted ceramic phase is preferably a SiC ceramic phase, a Si3N4 ceramic phase, a SiCN ceramic phase or a SiBCN ceramic phase.

[0033] In the composite absorbing material provided by the present invention, the ceramic matrix preferably accounts for 50-89% of the total volume of the material, specifically 50%, 52%, 55%, 57%, 58%, 60%, 62%, 65%, 67%, 70%, 72%, 75%, 78%, 80%, 82%, 85% or 89%.

[0034] In the composite absorbing material provided by the present invention, the ceramic matrix in the material mainly plays the role of supporting the overall structure of the composite material, optimizing the absorbing performance, and providing the high temperature stability and oxidation resistance of the absorbing material.

[0035] In the composite wave absorbing material provided by the present invention, the fiber reinforcement is composed of multiple layers of fiber cloth stacked together, and an interface layer is deposited on the surface of each layer of fiber cloth.

[0036] In the composite absorbing material provided by the present invention, the fibers in the multi-layer fiber cloth include multiple types of carbon fiber, silica fiber, silicon carbide fiber, glass fiber, alumina fiber and zirconium oxide fiber, preferably carbon fiber and silica fiber.

[0037] In the composite absorbing material provided by the present invention, the multi-layer fiber cloth preferably accounts for 10-40% of the total volume of the material, specifically 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39% or 40%.

[0038] In the composite wave-absorbing material provided by the present invention, the multi-layer fiber cloth mainly plays the role of enhancing the wave-absorbing performance and improving the mechanical strength and crack resistance of the material.

[0039] In the composite absorbing material provided by the present invention, the interface layer is one or more of a pyrolytic carbon (PyC) interface, a boron nitride (BN) interface, and a silicon carbide (SiC) interface. Among them, PyC has excellent electrical conductivity and thermal conductivity, can effectively convert electromagnetic waves into thermal energy, improve the absorbing efficiency, and at the same time enhance the bonding between the fiber and the matrix, improve the toughness of the composite material, especially maintain mechanical properties under high temperature and high stress environment; BN has a low dielectric constant, can improve impedance matching, and enhance the absorbing effect. Its high temperature resistance and chemical stability ensure that good absorbing performance is maintained at high temperatures, and enhance the bonding force of the material, improve structural strength and crack resistance; SiC has excellent high temperature resistance, corrosion resistance and electromagnetic wave absorption capacity, significantly improves the compression resistance, bending resistance and crack resistance, and at the same time enhances the absorbing effect, especially in extreme environments, and improves mechanical stability.

[0040] In the composite absorbing material provided by the present invention, the thickness of the single layer of the interface layer is preferably 0.1-2 μm, specifically 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm or 2 μm.

[0041] In the composite absorbing material provided by the present invention, the interface layer preferably accounts for 1-12% of the total volume of the material, specifically 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11% or 12%.

[0042] In the composite wave-absorbing material provided by the present invention, the interface layer mainly plays the role of promoting good bonding between the fiber and the matrix, and improving the structural toughness and high-temperature stability of the material.

[0043] The present invention also provides a method for preparing the fiber-reinforced barium titanate-polymer-converted ceramic-based composite absorbing material described in the above technical solution, comprising the following steps:

[0044] a) impregnating a fiber cloth having an interface layer deposited on the surface into a barium titanate ceramic slurry, and taking out and drying the fiber cloth after the impregnation is completed to obtain a fiber prepreg;

[0045] b) stacking the fiber prepreg sheets and then curing them under anaerobic conditions to obtain a fiber preform;

[0046] c) performing a binder removal treatment on the fiber preform under anaerobic conditions to obtain a fiber-reinforced barium titanate ceramic;

[0047] d) Impregnating the fiber-reinforced barium titanate ceramic into a polymer precursor, taking it out after the impregnation is completed and performing anaerobic thermal cracking to crack the impregnated polymer precursor into a ceramic phase, thereby obtaining a fiber-reinforced barium titanate-polymer conversion ceramic-based composite absorbing material.

[0048] In the preparation method provided by the present invention, in step a), the fiber cloth with an interface layer deposited on the surface is preferably prepared according to the following steps: arranging the fibers in a pyrolysis furnace for debinding treatment, and then placing them in a deposition furnace for interface layer deposition. Wherein, the fiber cloth is preferably a variety of carbon fiber cloth, silicon dioxide fiber cloth, silicon carbide fiber cloth, glass fiber cloth, alumina fiber cloth and zirconium oxide fiber cloth; the temperature for deposition of the interface layer is preferably 600-1100°C, specifically 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C or 1100°C; the time for deposition of the interface layer is preferably 10-100h, specifically 10h, 20h, 30h, 40h, 50h, 60h, 70h, 80h, 90h or 100h.

[0049] In the preparation method provided by the present invention, in step a), the components of the barium titanate ceramic slurry preferably include BaTiO3 powder, a dispersant, a binder, a plasticizer and a solvent.

[0050] In the preparation method provided by the present invention, in the above-mentioned barium titanate ceramic slurry, the particle size of the BaTiO3 powder is preferably 0.1~5μm, more preferably 0.1~0.5μm, specifically 0.1μm, 0.3μm, 0.5μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm or 5μm; the dispersant is preferably one or more of polyvinyl pyrrolidone, polyisobutylene and castor oil, more preferably castor oil; the binder is preferably one or more of polyethylene glycol, polyvinyl butyral, phenolic resin and polymethyl methacrylate, more preferably phenolic resin; the plasticizer is preferably one or more of methylcellulose, dibutyl phthalate and polyvinyl acetate, more preferably dibutyl phthalate; the solvent is preferably one or more of anhydrous ethanol, xylene, methanol and gasoline, more preferably anhydrous ethanol.

[0051] In the preparation method provided by the present invention, in the above-mentioned barium titanate ceramic slurry, the dispersant preferably accounts for 0.5-10wt% of the mass of the BaTiO3 powder, specifically 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt% or 10wt%; the binder preferably accounts for 2-20wt% of the mass of the BaTiO3 powder, specifically 2wt%, 4wt%, 6wt%, 8wt%, 10wt%, 12wt%, 14wt%, 16wt%, 18wt% or 20wt%; the plasticizer preferably accounts for 10wt% of the BaTiO3 powder. The mass content of the barium titanate ceramic slurry is 2~30wt%, specifically 2wt%, 5wt%, 7wt%, 10wt%, 12wt%, 15wt%, 17wt%, 20wt%, 23wt%, 25wt%, 27wt% or 30wt%; the solid content of the barium titanate ceramic slurry is preferably 15~50vol%, specifically 15vol%, 17vol%, 20vol%, 23vol%, 25vol%, 27vol%, 30vol%, 32vol%, 35vol%, 37vol%, 40vol%, 42vol%, 45vol%, 47vol% or 50vol%.

[0052] In the preparation method provided by the present invention, in step a), the barium titanate ceramic slurry is preferably prepared according to the following steps: BaTiO3 powder, binder, dispersant, plasticizer and solvent are ball-milled to obtain a uniform and stable BaTiO3 ceramic slurry. Wherein, the rotation speed of the ball milling is preferably 200-400r / min, specifically 200r / min, 230r / min, 250r / min, 270r / min, 300r / min, 320r / min, 350r / min, 370r / min or 400r / min; the time of the ball milling is preferably 2-24h, more preferably 6-12h, specifically 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h or 24h.

[0053] In the preparation method provided by the present invention, in step a), the impregnation method is preferably vacuum impregnation and / or vibration impregnation, and more preferably vacuum impregnation and vibration impregnation are performed in sequence. Wherein, the vacuum degree of the vacuum impregnation is preferably -0.1~-0.3MPa, specifically -0.1MPa, -0.15MPa, -0.2MPa, -0.25MPa or -0.3MPa; the time of the vacuum impregnation is preferably 2~12h, specifically 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h or 12h; the frequency of the vibration impregnation is preferably 40~120KHz, specifically 40KHz, 50KHz, 60KHz, 70KHz, 80KHz, 90KHz, 100KHz, 110KHz or 120KHz; the time of the vibration impregnation is preferably 0.5~12h, specifically 0.5h, 1h, 2h, 4h, 6h, 8h, 10h or 12h.

[0054] In the preparation method provided by the present invention, in step a), the drying method is preferably oven drying; the drying temperature is preferably 40-80°C, specifically 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C; the drying time is preferably 120-900s, specifically 120s, 150s, 200s, 250s, 300s, 400s, 500s, 600s, 700s, 800s or 900s.

[0055] In the preparation method provided by the present invention, in step b), the stacking method is preferably to alternately stack different types of fiber prepregs. Taking carbon fiber prepregs and silica fiber prepregs as an example, several layers of carbon fiber prepregs are used as a carbon fiber stacking unit, and several layers of silica fiber prepregs are used as a silica fiber stacking unit, and the carbon fiber stacking units and the silica fiber stacking units are alternately stacked; wherein the number of layers of carbon fiber prepregs in each of the carbon fiber stacking units is preferably 1 to 5 layers, specifically 1 layer, 2 layers, 3 layers, 4 layers or 5 layers; the number of layers of silica fiber prepregs in each of the silica fiber stacking units is preferably 1 to 5 layers, specifically 1 layer, 2 layers, 3 layers, 4 layers or 5 layers; the number of layers of the alternate stacking is preferably 2 to 15 times, specifically 2 times, 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times, 10 times, 11 times, 12 times, 13 times, 14 times or 15 times.

[0056] In the preparation method provided by the present invention, in step b), after the fiber prepreg sheets are stacked, they are preferably placed in a vacuum bag for vacuum packaging and then cured.

[0057] In the preparation method provided by the present invention, in step b), the anaerobic conditions of the curing treatment are preferably argon and / or nitrogen atmosphere, more preferably nitrogen atmosphere; the pressure of the curing treatment is preferably 100-1200 kPa, more preferably 500-900 kPa, specifically 100 kPa, 200 kPa, 300 kPa, 400 kPa, 500 kPa, 600 kPa, 700 kPa, 800 kPa, 900 kPa, 1000 kPa, 1100 kPa or 1200 kPa; the temperature of the curing treatment is preferably 120-200 ° C, specifically 120 ° C, 130 ° C, 140 ° C, 150 ° C, 160 ° C, 170 ° C, 180 ° C, 190 ° C or 200 ° C; the time of the curing treatment is preferably 1-4 h, specifically 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h or 4 h.

[0058] In the preparation method provided by the present invention, in step c), the anaerobic conditions of the debinding treatment are preferably vacuum or inert atmosphere, preferably argon atmosphere; the heating rate of the debinding treatment is preferably 1-10°C / min, specifically 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min or 10°C / min; the heating endpoint temperature of the debinding treatment is preferably 600-1200°C, specifically 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1150°C or 1200°C; the holding time of the debinding treatment is preferably 1-4h, specifically 1h, 1.5h, 2h, 2.5h, 3h, 3.5h or 4h.

[0059] In the preparation method provided by the present invention, in step d), the polymer precursor is preferably polycarbosilane (PCS) and / or polysilazane (PSN); the atmosphere of the anaerobic thermal cracking is preferably nitrogen and / or argon, and the gas flow rate is preferably 1-10 L / min, specifically 1 L / min, 2 L / min, 3 L / min, 4 L / min, 5 L / min, 6 L / min, 7 L / min, 8 L / min, 9 L / min or 10L / min; the temperature of the anaerobic thermal cracking is preferably 800-1200°C, specifically 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1150°C or 1200°C; the time of the anaerobic thermal cracking is preferably 0.5-6h, specifically 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h or 6h.

[0060] In the preparation method provided by the present invention, in order to further improve the density of the product, the product obtained in step d) is preferably subjected to step d) treatment repeatedly for multiple times until the weight gain of the product is ≤10%. In the present invention, the total number of times step d) treatment is performed is preferably 4 to 10 times, specifically 4 times, 5 times, 6 times, 7 times, 8 times, 9 times or 10 times.

[0061] In the preparation method provided by the present invention, the composition of the composite matrix can be regulated by controlling the solid content of the barium titanate ceramic slurry and the number of impregnations of the polymer precursor. The fiber reinforcement of the composite material can be regulated by changing the stacking structure of the fiber prepreg.

[0062] For the purpose of greater clarity, the invention is described in detail through the following examples.

[0063] Example 1

[0064] This embodiment intends to prepare SiO2f+Cf / PyC-SiCN (BaTiO3) ceramic matrix composite material, which includes a ceramic matrix and a fiber reinforcement embedded in the ceramic matrix; the ceramic matrix includes a BaTiO3 ceramic phase and a SiCN ceramic phase distributed around the BaTiO3 ceramic phase; the fiber reinforcement is composed of a plurality of layers of carbon fiber (Cf) cloth and silica fiber (SiO2f) cloth stacked and arranged, and a PyC interface layer is deposited on the surface of each layer of fiber cloth. In this embodiment, the ceramic matrix accounts for 62% of the total volume of the composite material, the Cf+SiO2f fiber cloth accounts for 30% of the total volume of the composite material, and the PyC interface layer accounts for 8% of the total volume of the composite material.

[0065] The specific preparation process of the above ceramic matrix composite material is as follows:

[0066] BaTiO3 powder (particle size of 300nm), plasticizer (dibutyl phthalate), dispersant (polyvinyl pyrrolidone), and binder (polyvinyl butyral) were added to ethanol, and the mass ratio of BaTiO3 powder, plasticizer, dispersant, and binder was 80:20:2:10. After ball milling for 6 hours, a uniform and stable BaTiO3 slurry was obtained, wherein the solid content of the slurry was 15vol%;

[0067] The carbon fiber cloth and silica fiber cut into appropriate sizes were placed in a pyrolysis furnace for debinding treatment, and then placed in a deposition furnace for PyC interface layer deposition. The interface layer thickness was 200 nm, the deposition temperature was 900 ° C, and the deposition time was 50 hours.

[0068] The carbon fiber cloth and the silica fiber cloth on which the PyC interface layer is deposited are immersed in the BaTiO3 slurry for vacuum impregnation and vibration impregnation in sequence. The vacuum degree of the vacuum impregnation is -0.2MPa and the impregnation time is 2 hours. The frequency of the vibration impregnation is 100KHz and the impregnation time is 4 hours. The fiber prepreg after impregnation is dried for standby use. The drying temperature is 40°C and the drying time is 600s.

[0069] The laminates were stacked alternately in the form of 1 layer of carbon fiber prepreg / 1 layer of silica fiber prepreg, and stacked 8 times in total to obtain a laminate consisting of 4 layers of carbon fiber prepreg and 4 layers of silica fiber prepreg, which was then cut into a fixed size; the cut laminate was placed in a vacuum bag for vacuum packaging, and then placed in an autoclave for curing and molding, with a curing protective atmosphere of nitrogen, an applied pressure of 500 kPa, a curing temperature of 140°C, and kept warm for 3 hours;

[0070] The cured sample was placed in a vacuum carbon tube furnace and subjected to binder removal treatment in an argon protective atmosphere to obtain a Cf+SiO2f / PyC / BaTiO3 ceramic preform; wherein the binder removal heating rate was 5°C / min, the binder removal temperature was 1100°C, and the holding time was 1 hour;

[0071] The Cf+SiO2f / PyC / BaTiO3 ceramic preform was vacuum impregnated with a polysilazane precursor and cracked; wherein the cracking atmosphere was nitrogen, the nitrogen flow rate was 5L / min, the cracking temperature was 900°C, and the insulation time was 2 hours; the polysilazane precursor was repeatedly impregnated and cracked for a total of 8 times to obtain a SiO2f+Cf / PyC-SiCN (BaTiO3) ceramic-based composite material.

[0072] The density, flexural strength and wave absorption performance of the composite material sample prepared in Example 1 were tested. The results showed that the final density of the SiO2f+Cf / PyC-SiCN (BaTiO3) composite material was 2.3 g / cm 3 The bending strength is 236.6±25.3MPa, the minimum reflection loss value is -16.5dB, and the effective absorption bandwidth is 5.72GHz.

[0073] The composite material prepared in Example 1 was observed by scanning electron microscopy and characterized by elemental composition. Figure 1 As shown, (a) is the overall microscopic morphology of the material, (b) and (c) are local enlarged views of (a); Figure 1 The element composition characterization results of the marked areas in (a) to (c) are shown in Tables 1 to 3:

[0074] Table 1 Element composition of region 1

[0075]

[0076] Table 2 Elemental composition of region 2

[0077]

[0078] Table 3 Elemental composition of region 3

[0079]

[0080] pass Figure 1 As can be seen from Tables 1 to 3, the material is mainly composed of C fibers and their C interfaces, SiO2 fibers, BaTiO3 and SiCN ceramic matrix, indicating that the expected structural design was successfully achieved.

[0081] Example 2

[0082] This embodiment intends to prepare SiO2f+Cf / PyC-SiCN (BaTiO3) ceramic matrix composite material, which includes a ceramic matrix and a fiber reinforcement embedded in the ceramic matrix; the ceramic matrix includes a BaTiO3 ceramic phase and a SiCN ceramic phase distributed around the BaTiO3 ceramic phase; the fiber reinforcement is composed of a plurality of layers of carbon fiber (Cf) cloth and silica fiber (SiO2f) cloth stacked and arranged, and a PyC interface layer is deposited on the surface of each layer of fiber cloth. In this embodiment, the ceramic matrix accounts for 58% of the total volume of the composite material, the Cf+SiO2f fiber cloth accounts for 32% of the total volume of the composite material, and the PyC interface layer accounts for 10% of the total volume of the composite material.

[0083] The specific preparation process of the above ceramic matrix composite material is as follows:

[0084] BaTiO3 powder (particle size of 300nm), plasticizer (dibutyl phthalate), dispersant (polyvinyl pyrrolidone), and binder (polyvinyl butyral) were added to ethanol. The mass ratio of BaTiO3 powder, plasticizer, dispersant, and binder was 90:20:4:5. After ball milling for 12 hours, a uniform and stable BaTiO3 slurry was obtained, wherein the solid content of the slurry was 20vol%;

[0085] The carbon fiber cloth and silica fiber cut into appropriate sizes were placed in a pyrolysis furnace for debinding treatment, and then placed in a deposition furnace for PyC interface layer deposition. The interface layer thickness was 400nm, the deposition temperature was 1000℃, and the deposition time was 80 hours.

[0086] The carbon fiber cloth and the silica fiber cloth on which the PyC interface layer is deposited are immersed in the BaTiO3 slurry for vacuum impregnation and vibration impregnation in sequence. The vacuum degree of the vacuum impregnation is -0.2MPa and the impregnation time is 2 hours. The frequency of the vibration impregnation is 80KHz and the impregnation time is 2 hours. The fiber prepreg after impregnation is dried for standby use. The drying temperature is 60°C and the drying time is 400s.

[0087] The laminates were stacked alternately in the form of 1 layer of carbon fiber prepreg / 2 layers of silica fiber prepreg, and stacked 6 times in total to obtain a laminate consisting of 3 layers of carbon fiber prepreg and 6 layers of silica fiber prepreg, which was then cut into a fixed size; the cut laminate was placed in a vacuum bag for vacuum packaging, and then placed in an autoclave for curing and molding, with a curing protective atmosphere of nitrogen, an applied pressure of 900 kPa, a curing temperature of 150°C, and kept warm for 3 hours;

[0088] The cured sample was placed in a vacuum carbon tube furnace and subjected to binder removal treatment in an argon protective atmosphere to obtain a Cf+SiO2f / PyC / BaTiO3 ceramic preform; wherein the binder removal heating rate was 3°C / min, the binder removal temperature was 1000°C, and the holding time was 1 hour;

[0089] The Cf+SiO2f / PyC / BaTiO3 ceramic preform was vacuum impregnated with a polysilazane precursor and cracked; wherein the cracking atmosphere was nitrogen, the nitrogen flow rate was 5L / min, the cracking temperature was 800°C, and the insulation time was 2 hours; the polysilazane precursor was repeatedly impregnated and cracked for a total of 8 times to obtain a SiO2f+Cf / PyC-SiCN (BaTiO3) ceramic-based composite material.

[0090] The density, flexural strength and wave absorption performance of the composite material sample prepared in Example 2 were tested. The results showed that the final density of the SiO2f+Cf / PyC-SiCN (BaTiO3) composite material was 2.1 g / cm 3 The bending strength is 216.6±31.3MPa, the minimum reflection loss value is -19.1dB, and the effective absorption bandwidth is 5.01GHz.

[0091] Example 3

[0092] This embodiment intends to prepare SiO2f+Cf / PyC-SiCN (BaTiO3) ceramic matrix composite material, which includes a ceramic matrix and a fiber reinforcement embedded in the ceramic matrix; the ceramic matrix includes a BaTiO3 ceramic phase and a SiCN ceramic phase distributed around the BaTiO3 ceramic phase; the fiber reinforcement is composed of a plurality of layers of carbon fiber (Cf) cloth and silica fiber (SiO2f) cloth stacked and arranged, and a PyC interface layer is deposited on the surface of each layer of fiber cloth. In this embodiment, the ceramic matrix accounts for 57% of the total volume of the composite material, the Cf+SiO2f fiber cloth accounts for 32% of the total volume of the composite material, and the PyC interface layer accounts for 11% of the total volume of the composite material.

[0093] The specific preparation process of the above ceramic matrix composite material is as follows:

[0094] BaTiO3 powder (particle size of 300nm), plasticizer (dibutyl phthalate), dispersant (polyvinyl pyrrolidone), and binder (polyvinyl butyral) were added to ethanol. The mass ratio of BaTiO3 powder, plasticizer, dispersant, and binder was 100:15:6:8. After ball milling for 12 hours, a uniform and stable BaTiO3 slurry was obtained, wherein the solid content of the slurry was 25vol%;

[0095] The carbon fiber cloth and silica fiber cut into appropriate sizes were placed in a pyrolysis furnace for debinding treatment, and then placed in a deposition furnace for PyC interface layer deposition. The interface phase thickness was 1000nm, the deposition temperature was 1100℃, and the deposition time was 100 hours.

[0096] The carbon fiber cloth and the silica fiber cloth on which the PyC interface layer is deposited are immersed in the BaTiO3 slurry for vacuum impregnation and vibration impregnation in sequence. The vacuum degree of the vacuum impregnation is -0.3MPa and the impregnation time is 6 hours. The frequency of the vibration impregnation is 120KHz and the impregnation time is 1 hour. The fiber prepreg after impregnation is dried for standby use. The drying temperature is 80°C and the drying time is 120s.

[0097] The laminates were stacked alternately in the form of 1 layer of carbon fiber prepreg / 3 layers of silica fiber prepreg, and stacked 6 times in total to obtain a laminate consisting of 3 layers of carbon fiber prepreg and 9 layers of silica fiber prepreg, which was then cut into a fixed size; the cut laminate was placed in a vacuum bag for vacuum packaging, and then placed in an autoclave for curing and molding, with a curing protective atmosphere of nitrogen, an applied pressure of 700 kPa, a curing temperature of 120°C, and kept warm for 1 hour;

[0098] The cured sample was placed in a vacuum carbon tube furnace and subjected to binder removal treatment in an argon protective atmosphere to obtain a Cf+SiO2f / PyC / BaTiO3 ceramic preform; wherein the binder removal heating rate was 1°C / min, the binder removal temperature was 900°C, and the holding time was 2 hours;

[0099] The Cf+SiO2f / PyC / BaTiO3 ceramic preform was vacuum impregnated with a polysilazane precursor and cracked; wherein the cracking atmosphere was nitrogen, the nitrogen flow rate was 3L / min, the cracking temperature was 700°C, and the insulation time was 1 hour; the polysilazane precursor was repeatedly impregnated and cracked for a total of 8 times to obtain a SiO2f+Cf / PyC-SiCN (BaTiO3) ceramic-based composite material.

[0100] The density, flexural strength and wave absorption performance of the composite material sample prepared in Example 3 were tested. The results showed that the final density of the SiO2f+Cf / PyC-SiCN (BaTiO3) composite material was 2.2 g / cm 3 The bending strength is 237.1±23.2MPa, the minimum reflection loss value is -15.9dB, and the effective absorption bandwidth is 4.88GHz.

[0101] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a fiber-reinforced barium titanate-polymer-converted ceramic-based composite absorbing material, characterized in that: The following steps are involved: a) impregnating a fiber cloth having an interface layer deposited on the surface into a barium titanate ceramic slurry, and taking out and drying the fiber cloth after the impregnation is completed to obtain a fiber prepreg; In step a), the components of the barium titanate ceramic slurry include BaTiO3 powder, dispersant, binder, plasticizer and solvent, the dispersant accounts for 0.5-10wt% of the mass of the BaTiO3 powder, the binder accounts for 2-20wt% of the mass of the BaTiO3 powder, the plasticizer accounts for 2-30wt% of the mass of the BaTiO3 powder, and the solid content of the barium titanate ceramic slurry is 15-50vol%; In step a), the impregnation method is vacuum impregnation and / or vibration impregnation; the vacuum degree of the vacuum impregnation is -0.1~-0.3MPa, and the time is 2~12h; the frequency of the vibration impregnation is 40~120KHz, and the time is 0.5~12h; the drying temperature is 40~80℃, and the time is 120~900s; b) stacking the fiber prepreg sheets and then curing them under anaerobic conditions to obtain a fiber preform; c) performing a binder removal treatment on the fiber preform under anaerobic conditions to obtain a fiber-reinforced barium titanate ceramic; d) impregnating the fiber-reinforced barium titanate ceramic into a polymer precursor, taking it out after the impregnation is completed and performing oxygen-free thermal cracking to crack the impregnated polymer precursor into a ceramic phase; e) Repeating step d) on the product obtained in step d), performing step d) for 4 to 10 times in total, to obtain a fiber-reinforced barium titanate-polymer-converted ceramic-based composite absorbing material; The fiber-reinforced barium titanate-polymer converted ceramic-based composite absorbing material includes a ceramic matrix and a fiber reinforcement embedded in the ceramic matrix; the ceramic matrix includes a barium titanate ceramic phase and a polymer converted ceramic phase distributed around the barium titanate ceramic phase; the fiber reinforcement is composed of multiple layers of fiber cloth stacked together, and an interface layer is deposited on the surface of each layer of fiber cloth; the fibers in the multiple layers of fiber cloth include multiple types of carbon fiber, silicon dioxide fiber, silicon carbide fiber, glass fiber, aluminum oxide fiber and zirconium oxide fiber, and the interface layer is one or more of a PyC interface, a BN interface and a SiC interface.

2. The preparation method according to claim 1, characterized in that: In step a), the particle size of the BaTiO3 powder is 0.1-5 μm; the dispersant is one or more of polyvinyl pyrrolidone, polyisobutylene and castor oil; the binder is one or more of polyethylene glycol, polyvinyl butyral, phenolic resin and polymethyl methacrylate; the plasticizer is one or more of methyl cellulose, dibutyl phthalate and polyvinyl acetate; the solvent is one or more of anhydrous ethanol, xylene, methanol and gasoline.

3. The preparation method according to claim 1, characterized in that: In step b), the oxygen-free condition is an argon and / or nitrogen atmosphere; the pressure of the curing treatment is 100-1200 kPa, the temperature is 120-200° C., and the time is 1-4 hours.

4. The preparation method according to claim 1, characterized in that: In step c), the oxygen-free condition is a vacuum or an inert atmosphere; the heating rate of the debinding treatment is 1-10°C / min, the heating end temperature is 600-1200°C, and the holding time is 1-4h.

5. The preparation method according to claim 1, characterized in that: In step d), the polymer precursor is polycarbosilane and / or polysilazane; the atmosphere of the oxygen-free thermal cracking is nitrogen and / or argon, the temperature is 800-1200° C., and the time is 0.5-6 hours.

6. The preparation method according to claim 1, characterized in that: The polymer-converted ceramic phase is a SiC ceramic phase, a Si3N4 ceramic phase, a SiCN ceramic phase or a SiBCN ceramic phase.

7. The preparation method according to claim 1, characterized in that: The thickness of a single layer of the interface layer is 0.1-2 μm.

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