Frequency-adjustable multiphase enhanced polymer-derived wave-absorbing ceramic composite material and preparation method and application thereof

Abstract

The invention provides a frequency-adjustable multiphase enhanced polymer-derived wave-absorbing ceramic composite material and a preparation method and application thereof, and the frequency-adjustable multiphase enhanced polymer-derived wave-absorbing ceramic composite material comprises the following components by volume: 35-87% of a polymer-derived ceramic matrix; 10 to 40 percent of fiber; 1%-10% of a fiber interface; 1-10% of a dielectric ceramic phase; and 1-5% of ceramic hollow balls. Through the combined action of multiple components, the broadband and high-strength wave absorbing performance of the composite material is achieved; the mechanical property is also obviously improved. Experimental results show that the reflection loss of the composite material in multiple frequency bands can reach-10dB or below, and the lowest reflection loss can reach-21dB or above.

Description

Technical Field

[0001] The present invention belongs to the technical field of wave-absorbing ceramic composite materials, and in particular relates to a frequency-adjustable multiphase reinforced polymer-derived wave-absorbing ceramic composite material, a preparation method thereof, and applications thereof. Background Art

[0002] With the rapid development of modern electronics and communications technologies, the widespread use of electromagnetic waves has led to increasingly serious problems of electromagnetic interference and pollution. To effectively address these issues, the research and development of absorbing materials has garnered widespread attention. Ideal absorbing materials should possess properties such as light weight, thinness, broadband bandwidth, and strong absorption, while also being able to adjust their frequency bands to meet diverse application requirements.

[0003] However, traditional absorbing materials often struggle to meet these requirements simultaneously. For example, single-component absorbing materials often suffer from problems such as a narrow absorption band and insufficient absorption intensity. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a frequency-adjustable multiphase reinforced polymer-derived microwave-absorbing ceramic composite material, and a preparation method and application thereof, wherein the composite material has excellent microwave-absorbing performance.

[0005] The present invention provides a frequency-adjustable multiphase reinforced polymer-derived microwave-absorbing ceramic composite material, characterized in that it comprises the following components, calculated by volume percentage:

[0006] The polymer-derived ceramic matrix is ​​35-87%; the fiber is 10-40%; the fiber interface is 1-10%; the dielectric ceramic phase is 1-10%; and the ceramic hollow sphere is 1-5%.

[0007] Preferably, the polymer-derived ceramic matrix is ​​selected from one or more of polycarbosilane, polyborazane and polysilazane;

[0008] The fiber is selected from one or more of carbon fiber, silicon carbide fiber, alumina fiber and glass fiber;

[0009] The fiber interface is selected from one or more of a pyrolytic carbon interface, a boron nitride interface, and a silicon carbide interface;

[0010] The dielectric ceramic phase is selected from one or more of bismuth ferrite, barium titanate, calcium bismuth niobate and lead zirconate titanate; the size of the dielectric ceramic phase is 50 to 500 nm;

[0011] The hollow ceramic spheres are selected from one or more of hollow alumina spheres, hollow glass microspheres, hollow floating beads and hollow silicon carbide spheres, and the diameter of the hollow ceramic spheres is 10 to 100 μm.

[0012] The present invention provides a method for preparing the frequency-adjustable multiphase reinforced polymer-derived microwave-absorbing ceramic composite material described in the above technical solution, comprising the following steps:

[0013] Step 1) mixing dielectric ceramic powder, ceramic hollow balls, a binder, a dispersant, a plasticizer and a solvent, and ball milling to obtain a mixed ceramic slurry;

[0014] Step 2), cutting the fiber cloth, removing the glue, and depositing the interface phase;

[0015] Step 3), coating the fiber cloth obtained in step 2) with the mixed ceramic slurry obtained in step 1), then impregnating the fiber cloth, and drying the fiber cloth to obtain a fiber prepreg;

[0016] Step 4) laminating the fiber prepreg sheets obtained in step 3) and vacuum sealing the layers, and curing them at a certain temperature and pressure to obtain a fiber preform;

[0017] Step 5), debinding the fiber preform to obtain a fiber-reinforced multiphase ceramic preform;

[0018] Step 6), vacuum-vibrating impregnation of the fiber-reinforced multiphase ceramic preform with a polymer-converted ceramic precursor and cracking the preform;

[0019] Step 7) Repeat step 6) n times to obtain a frequency-adjustable multiphase reinforced polymer-derived microwave-absorbing ceramic composite material.

[0020] Preferably, the dispersant is selected from one or more of polyvinylpyrrolidone, polyisobutylene and castor oil;

[0021] The binder is selected from one or more of polyethylene glycol, polyvinyl butyral, phenolic resin and polymethyl methacrylate;

[0022] The plasticizer is selected from one or more of methyl cellulose, dibutyl phthalate and polyvinyl acetate;

[0023] The solvent is selected from one or more of anhydrous ethanol, xylene, methanol and gasoline.

[0024] Preferably, the deposition temperature in step 2) is 600-1100° C., and the deposition time is 100-1000 h;

[0025] The thickness of the deposited interface phase is 0.1 to 2 μm.

[0026] Preferably, the impregnation method in step 3) is vacuum impregnation or vibration impregnation;

[0027] The vacuum degree of the vacuum impregnation is -0.1 to -0.3 MPa, and the vacuum impregnation time is 2 to 12 hours;

[0028] The frequency of the vibration impregnation is 40 to 120 kHz, and the time of the vibration impregnation is 0.5 to 12 hours;

[0029] The drying temperature is 40-80°C, and the drying time is 120-900s.

[0030] Preferably, the curing atmosphere in step 4) is argon or nitrogen; the pressure is 100-1200 kPa, the curing temperature is 120-200° C., and the curing time is 1-4 hours;

[0031] In step 5), the debinding atmosphere is a vacuum or inert atmosphere; the debinding temperature is 600-1200° C., and the debinding time is 1-4 hours.

[0032] Preferably, in step 6), the polymer-converted ceramic precursor is polyborazane, polycarbosilane or polysilazane;

[0033] The cracking atmosphere is nitrogen or argon, the cracking temperature is 800-1200°C, and the cracking time is 0.5-6h.

[0034] Preferably, the number of deposition times n in step 7) is 5 to 12 times.

[0035] The present invention provides an application of the frequency-adjustable multiphase reinforced polymer-derived wave-absorbing ceramic composite material described in the above technical solution in aerospace, military equipment or electronic equipment.

[0036] The present invention provides a frequency-tunable, multiphase-reinforced polymer-derived microwave-absorbing ceramic composite material. The composite material comprises the following components, calculated by volume: 35-87% polymer-derived ceramic matrix; 10-40% fiber; 1-10% fiber interface; 1-10% dielectric ceramic phase; and 1-5% hollow ceramic spheres. Through the combined action of these components, the composite material achieves broadband, high-strength microwave absorption performance, while also significantly improving mechanical properties. Experimental results demonstrate that the composite material exhibits a reflection loss below -10 dB across multiple frequency bands, with the lowest reflection loss exceeding -21 dB. The composite also exhibits a flexural strength ranging from 274.4±35.8 MPa to 301.5±14.1 MPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The flexural strength and wave absorption performance of the composite material sample prepared in Example 1;

[0038] Figure 2 The bending strength and wave absorption performance of the composite material sample prepared in Example 2;

[0039] Figure 3 The micromorphology and elemental composition of the fiber region in the composite material prepared in Example 2;

[0040] Figure 4 The microscopic morphology and elemental composition of the hollow floating beads in the composite material prepared in Example 2;

[0041] Figure 5 Elemental composition diagram of BaTiO3 particles in the composite material prepared in Example 2;

[0042] Figure 6 The bending strength and wave absorption performance of the composite material sample prepared in Example 3. DETAILED DESCRIPTION

[0043] The present invention provides a frequency-adjustable multiphase reinforced polymer-derived wave-absorbing ceramic composite material, which comprises the following components, calculated by volume percentage:

[0044] The polymer-derived ceramic matrix is ​​35-87%; the fiber is 10-40%; the fiber interface is 1-10%; the dielectric ceramic phase is 1-10%; and the ceramic hollow sphere is 1-5%.

[0045] The frequency-adjustable multiphase reinforced polymer-derived microwave-absorbing ceramic composite material provided by the present invention comprises 35-87% of a polymer-derived ceramic matrix, and the specific content can be 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% or 87%; the polymer-derived ceramic matrix is ​​selected from one or more of polycarbosilane, polyborazane and polysilazane;

[0046] The frequency-tunable, multiphase-reinforced, polymer-derived microwave-absorbing ceramic composite material provided herein comprises 10-40% fiber; specifically, the content can be 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, or 40%. The fiber is selected from one or more of carbon fiber, silicon carbide fiber, alumina fiber, and glass fiber. The use of these fibers significantly improves the mechanical properties of the composite material.

[0047] The frequency-tunable multiphase reinforced polymer-derived microwave-absorbing ceramic composite material provided by the present invention includes 1% to 10% of a fiber interface; the content can specifically be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%. The fiber interface is selected from one or more of pyrolytic carbon (PyC), boron nitride (BN) and silicon carbide (SiC);

[0048] The frequency-tunable multiphase reinforced polymer-derived microwave-absorbing ceramic composite material provided by the present invention includes 1 to 10% of a dielectric ceramic phase; the content can specifically be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%. The dielectric ceramic phase is selected from one or more of bismuth ferrite, barium titanate, calcium bismuth niobate, and lead zirconate titanate; the size of the dielectric ceramic phase is 50 to 500 nm;

[0049] The frequency-tunable, multiphase-reinforced, polymer-derived microwave-absorbing ceramic composite material provided herein includes 1 to 5% ceramic hollow spheres; the specific content can be 1%, 2%, 3%, 4%, or 5%. The ceramic hollow spheres are selected from one or more of alumina hollow spheres, hollow glass microspheres, hollow floating beads, and silicon carbide hollow spheres, and have a diameter of 10 to 100 μm. The presence of the ceramic hollow spheres imparts frequency tunability to the composite material, adapting it to different electromagnetic environments.

[0050] In a specific embodiment of the present invention, the frequency-tunable multiphase reinforced polymer-derived microwave-absorbing ceramic composite material comprises 60% polymer-derived ceramic matrix, 25% silicon carbide fiber, 3% BN interface, 9% bismuth ferrite, and 3% alumina hollow spheres;

[0051] or comprising polymer-derived ceramic matrix 55%, carbon fiber 30%, PyC interface 5%, barium titanate 7%, hollow floating beads 3%;

[0052] Or include polymer derived ceramic matrix 50%, glass fiber 35%, SiC interface 7%, bismuth calcium niobate 6%, silicon carbide hollow sphere 2%.

[0053] The present invention provides a method for preparing the frequency-adjustable multiphase reinforced polymer-derived microwave-absorbing ceramic composite material described in the above technical solution, comprising the following steps:

[0054] Step 1) mixing dielectric ceramic powder, ceramic hollow balls, a binder, a dispersant, a plasticizer and a solvent, and ball milling to obtain a mixed ceramic slurry;

[0055] Step 2), cutting the fiber cloth, removing the glue, and depositing the interface phase;

[0056] Step 3), coating the fiber cloth obtained in step 2) with the mixed ceramic slurry obtained in step 1), then impregnating the fiber cloth, and drying the fiber cloth to obtain a fiber prepreg;

[0057] Step 4) laminating the fiber prepreg sheets obtained in step 3) and vacuum sealing the layers, and curing them at a certain temperature and pressure to obtain a fiber preform;

[0058] Step 5), debinding the fiber preform to obtain a fiber-reinforced multiphase ceramic preform;

[0059] Step 6), vacuum-vibrating impregnation of the fiber-reinforced multiphase ceramic preform with a polymer-converted ceramic precursor and cracking the preform;

[0060] Step 7) Repeat step 6) n times to obtain a frequency-adjustable multiphase reinforced polymer-derived microwave-absorbing ceramic composite material.

[0061] The present invention adopts a ceramic slurry and precursor impregnation and cracking method to step-by-step introduce dielectric ceramic phase, ceramic hollow spheres and polymer-converted ceramic matrix into the fiber preform, and then combines high-temperature debinding, cracking and densification treatment processes to finally obtain a new composite material with excellent wave absorbing performance and frequency band adjustability.

[0062] In a specific embodiment of the present invention, precise control of the composition and structure of the composite material can be achieved by controlling the type and content of the dielectric ceramic phase and the hollow ceramic spheres, as well as the concentration and number of impregnations of the polymer-converted ceramic precursor solution; and by changing the type, content, and arrangement of the fibers, the mechanical properties and electromagnetic wave absorption characteristics of the material can be further optimized.

[0063] The present invention mixes dielectric ceramic powder, hollow ceramic spheres, a binder, a dispersant, a plasticizer, and a solvent, and ball-mills the mixture to produce a mixed ceramic slurry. In the present invention, the dielectric ceramic powder is selected from one or more of bismuth ferrite powder, barium titanate powder, calcium bismuth niobate powder, and lead zirconate titanate powder; the size of the dielectric ceramic powder is 50 to 500 nm. In the present invention, the dispersant is selected from one or more of polyvinyl pyrrolidone, polyisobutylene, and castor oil, preferably castor oil. The binder is selected from one or more of polyethylene glycol, polyvinyl butyral, phenolic resin, and polymethyl methacrylate, preferably phenolic resin. The plasticizer is selected from one or more of methylcellulose, dibutyl phthalate, and polyvinyl acetate, preferably dibutyl phthalate. The solvent is selected from one or more of anhydrous ethanol, xylene, methanol, and gasoline, preferably anhydrous ethanol.

[0064] In the present invention, the dielectric ceramic powder is selected from one or more of bismuth ferrite, barium titanate, calcium bismuth niobate, and lead zirconate titanate; the particle size of the dielectric ceramic powder is preferably 50 to 500 nm. The hollow ceramic spheres are selected from one or more of hollow alumina spheres, hollow glass microspheres, hollow floating beads, and hollow silicon carbide spheres; and the diameter of the hollow ceramic spheres is 10 to 100 μm.

[0065] In the present invention, the mass ratio of the dielectric ceramic powder to the ceramic hollow sphere is (2-3):(1-2). The sum of the mass of the dispersant, binder, and plasticizer accounts for 0.5wt% to 40wt% of the total mass of the dielectric ceramic powder and the ceramic hollow sphere; preferably, the dispersant accounts for 0.5wt% to 5wt% of the total mass of the dielectric ceramic powder and the ceramic hollow sphere, the binder accounts for 5wt% to 10wt% of the total mass of the dielectric ceramic powder and the ceramic hollow sphere, and the plasticizer accounts for 5wt% to 25wt% of the total mass of the dielectric ceramic powder and the ceramic hollow sphere.

[0066] In the present invention, the ball milling speed is 100 to 400 rpm, specifically 100 rpm, 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, or 400 rpm; the ball milling time is 2 to 24 hours, preferably 6 to 12 hours, and more preferably 8 to 10 hours. The ball milling time is specifically 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, or 12 hours.

[0067] In the present invention, the solid content of the mixed ceramic slurry is 15-50 vol%, specifically 15 vol%, 20 vol%, 25 vol%, 30 vol%, 35 vol%, 40 vol%, 45 vol% or 50 vol%.

[0068] The present invention cuts the fiber cloth, removes the binder, and deposits an interfacial phase. The fiber cloth is cut into the desired shape. The interfacial phase has the functions of transferring loads, relieving stress, and deflecting cracks. Therefore, to improve the mechanical properties of the composite material, an interfacial phase is deposited on the fiber cloth. The deposited interfacial phase is selected from a PyC interface, a BN interface, or a SiC interface. Considering the temperature resistance of oxide fibers, the PyC interface is preferably used as the interfacial phase. The fiber cloth is preferably silicon carbide fiber cloth, carbon fiber cloth, or glass fiber cloth.

[0069] The present invention first places fibers cut into appropriate sizes in a cracking furnace for debinding, and then places them in a deposition furnace for interfacial phase deposition. In the present invention, the deposition temperature is 600-1100°C, specifically 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, or 1000°C; and the deposition time is 100-1000 hours, specifically 100 hours, 200 hours, 300 hours, 400 hours, 500 hours, 600 hours, 700 hours, 800 hours, 900 hours, or 1000 hours. The thickness of the interface phase is 0.1 to 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, 1.0 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 2.0 μm, preferably 0.1 to 1 μm.

[0070] In the present invention, the preparation order of step 1) and step 2) is not important.

[0071] The present invention coats the fiber cloth after depositing the interface phase with the mixed ceramic slurry, then impregnates it and dries it to obtain a fiber prepreg. In the present invention, the impregnation method is vacuum impregnation or vibration impregnation; the vacuum degree of the vacuum impregnation is -0.1 to -0.3 MPa, specifically -0.1 MPa, -0.15 MPa, -0.20 MPa, -0.25 MPa, or -0.30 MPa; and the vacuum impregnation time is 2 to 12 hours, specifically 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, or 12 hours. The frequency of the vibration immersion is 40 to 120 kHz, specifically 40 kHz, 50 kHz, 60 kHz, 70 kHz, 80 kHz, 90 kHz, 100 kHz, 110 kHz or 120 kHz; the time of the vibration immersion is 0.5 to 12 h, specifically 0.5 h, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h or 12 h. The drying temperature is 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 120-900s, specifically 120s, 150s, 200s, 250s, 300s, 350s, 400s, 450s, 500s, 550s, 600s, 650s, 700s, 750s, 800s, 850s or 900s.

[0072] After obtaining the fiber prepreg sheets, the present invention stacks the fiber prepreg sheets, vacuum seals them, and cures them at a certain temperature and pressure to obtain a fiber preform. The number of layers in the stack is 6 to 12, specifically 6, 7, 8, 9, 10, 11, or 12. In the present invention, the curing atmosphere is argon or nitrogen, preferably nitrogen; the pressure is 100-1200 kPa, preferably 500-900 kPa, specifically 500 kPa, 550 kPa, 600 kPa, 650 kPa, 700 kPa, 750 kPa, 800 kPa, 850 kPa or 900 kPa; the curing temperature is 120-200 ° C, specifically 120 ° C, 130 ° C, 140 ° C, 150 ° C, 160 ° C, 170 ° C, 180 ° C, 190 ° C or 200 ° C; the curing time is 1-4 h, specifically 1 h, 1.5 h, 2.0 h, 2.5 h, 3 h, 3.5 h or 4 h.

[0073] After obtaining the fiber preform, the present invention debinds the fiber preform to obtain a fiber-reinforced multiphase ceramic preform. In the present invention, the debinding atmosphere is a vacuum or inert atmosphere; the debinding temperature is 600 to 1200° C., and the debinding time is 1 to 4 hours.

[0074] After obtaining the fiber-reinforced multiphase ceramic preform, in order to further improve the density, the present invention vacuum-vibrates and impregnates the fiber-reinforced multiphase ceramic preform with a polymer-converted ceramic precursor and pyrolyzes it. In the present invention, the polymer-converted ceramic precursor is polyborazane, polycarbosilane (PCS), or polysilazane (PSN); the pyrolysis atmosphere is nitrogen or argon; if nitrogen is used, the nitrogen flow rate is 1 to 10 L / min; the pyrolysis temperature is 800 to 1200°C, specifically 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1150°C, or 1200°C; and the pyrolysis time is 0.5 to 6 hours, specifically 0.5h, 1h, 1.5h, 2.0h, 2.5h, 3.0h, 3.5h, 4h, 4.5h, 5h, 5.5h, or 6h.

[0075] The present invention repeats step 6) n times to obtain a frequency-tunable multiphase reinforced polymer-derived microwave-absorbing ceramic composite material. In the present invention, the number of depositions n is 5 to 12 times, preferably 5 to 10 times. The present invention repeatedly impregnates the polymer-converted ceramic precursor solution and pyrolyzes it until the weight gain of the composite material is less than 10 wt%, thereby obtaining a frequency-tunable multiphase reinforced polymer-derived microwave-absorbing ceramic composite material.

[0076] The density, flexural strength and absorbing performance of the obtained frequency-adjustable multiphase reinforced polymer-derived absorbing ceramic composite material are tested by the Archimedes drainage method (GB / T25995), the three-point bending method (GB / T6569-2006) and the coaxial method (GB / T 35680-2017).

[0077] The present invention provides an application of the frequency-tunable multiphase reinforced polymer-derived microwave-absorbing ceramic composite material described in the above technical solution in aerospace, military equipment, or electronic equipment. The composite material has broad application prospects in the fields of electromagnetic wave absorption, radar stealth, etc.

[0078] To further illustrate the present invention, a frequency-adjustable multiphase reinforced polymer-derived microwave-absorbing ceramic composite material, a preparation method thereof, and applications thereof are described in detail below in conjunction with examples. However, these examples should not be construed as limiting the scope of protection of the present invention.

[0079] Example 1

[0080] Step 1: Preparation of mixed ceramic slurry: Mix 60 g of bismuth ferrite powder (particle size 200 nm), 30 g of hollow alumina spheres (diameter 50 μm), 0.9 g of castor oil (dispersant), 5.4 g of phenolic resin (binder), 5.4 g of dibutyl phthalate (plasticizer) and 100 ml of anhydrous ethanol (solvent), and ball mill at 150 r / min for 8 h to obtain a uniform and stable mixed ceramic slurry.

[0081] Step 2: Cut the silicon carbide fiber cloth into a 60mm×60mm square. After debinding, deposit the BN interface at 900°C for 200 hours and the interface thickness is 0.8μm.

[0082] Step 3: The fiber cloth obtained in step 2 is coated with the mixed ceramic slurry obtained in step 1, immersed in a vacuum of -0.2 MPa for 4 hours, and then dried at 60° C. for 300 seconds to obtain a fiber prepreg.

[0083] Step 4: Lay 8 layers of the fiber prepreg sheets obtained in step 3 in a vacuum bag and seal them, and cure them in a nitrogen atmosphere at a pressure of 700 kPa and a temperature of 160° C. for 2 hours to obtain a fiber preform.

[0084] Step 5: The fiber preform obtained in step 4 is heated to 900° C. at a heating rate of 5° C. / min under an argon atmosphere and kept at this temperature for 1.5 hours for debinding treatment to obtain a fiber-reinforced multiphase ceramic preform.

[0085] Step 6: The preform obtained in step 5 was impregnated with a polycarbosilane (PCS) precursor and cracked at 1000° C. for 2 hours under a nitrogen atmosphere (flow rate 5 L / min).

[0086] Step 7: Repeat step 6 for a total of 7 times to obtain a relatively dense multiphase reinforced polymer-derived absorbing ceramic composite material.

[0087] The volume percentages of the components of the final composite material are as follows: 60% of polymer-derived ceramic matrix, 25% of silicon carbide fiber, 3% of BN interface, 9% of bismuth ferrite, and 3% of hollow alumina spheres.

[0088] The present invention performs density, flexural strength, and wave absorbing performance tests on the composite material sample prepared in Example 1. Figure 1 The bending strength and wave absorbing performance of the composite material sample prepared in Example 1 are as follows: Figure 1 It can be seen that the sample has a strong structural bearing capacity, strong wave absorbing ability and wide effective wave absorbing width. The final density of the composite material is 2.3g / cm 3 The bending strength and absorption performance are 274.4±35.8MPa respectively, the minimum reflection loss value is -14.5dB, and the effective absorption bandwidth is 1.76GHz.

[0089] Example 2

[0090] A frequency-tunable multiphase reinforced polymer-derived microwave-absorbing ceramic composite material was prepared according to the method of Example 1, except that:

[0091] (1) In step 1, 50 g of barium titanate powder (particle size 300 nm) and 40 g of hollow floating beads (diameter 30 μm) were used;

[0092] (2) Using carbon fiber cloth in step 2, a PyC interface was deposited with an interface thickness of 0.5 μm;

[0093] (3) using a polysilazane (PSN) precursor in step 6;

[0094] (4) Repeat step 7 8 times.

[0095] The volume percentages of the components of the final composite material are: 55% polymer-derived ceramic matrix, 30% carbon fiber, 5% PyC interface, 7% barium titanate, and 3% hollow glass spheres.

[0096] The present invention tests the density, flexural strength and wave absorption performance of the composite material sample prepared in Example 2. The final density of the composite material is 2.4g / cm 3 . Figure 2 The bending strength and wave absorbing performance of the composite material sample prepared in Example 2 are as follows: Figure 2 It can be seen that the bending strength of the sample is slightly improved and the absorption width is significantly widened compared to the sample in Example 1. The bending strength and absorption performance are 289.7±24.8MPa respectively, the minimum reflection loss value is -21.2dB, and the effective absorption bandwidth is 3.98GHz.

[0097] At the same time, the micromorphology and elemental composition of the composite materials were characterized, such as Figures 3 to 5 As shown, Figure 3 The micromorphology and elemental composition of the fiber region in the composite material prepared in Example 2 are shown in FIG. Figure 3 It can be seen that there are C fibers and C interfaces inside the material; Figure 4 The microscopic morphology and elemental composition of the hollow floating beads in the composite material prepared in Example 2 are shown in FIG. Figure 4 It can be seen that there are semi-shell particles distributed inside the material matrix, which are mainly composed of Al2O3 and SiO2; Figure 5 The element composition diagram of BaTiO3 particles in the composite material prepared in Example 2 is shown in FIG. Figure 5 The results show that BaTiO3 particles were successfully introduced into the material. The composite material is mainly composed of C fibers and their C interfaces, BaTiO3 and SiC ceramic matrix, indicating that the expected structural design was successfully achieved.

[0098] Example 3

[0099] A frequency-tunable multiphase reinforced polymer-derived microwave-absorbing ceramic composite material was prepared according to the method of Example 1, except that:

[0100] (1) In step 1, 70 g of calcium bismuth niobate powder (particle size 150 nm) and 20 g of hollow silicon carbide spheres (diameter 80 μm) were used;

[0101] (2) In step 2, glass fiber cloth was used to deposit the SiC interface with an interface thickness of 1.2 μm;

[0102] (3) stacking 12 layers in step 4;

[0103] (4) Repeat step 7 6 times.

[0104] The volume percentages of the components of the final composite material are as follows: 50% polymer-derived ceramic matrix, 35% glass fiber, 7% SiC interface, 6% bismuth calcium niobate, and 2% silicon carbide hollow spheres.

[0105] Figure 6 The bending strength and wave absorbing performance of the composite material sample prepared in Example 3 are as follows: Figure 6 It can be seen that the bending strength of the sample is slightly higher than that of the sample in Example 2, but the effective wave absorbing capacity is reduced. The final density of the composite material prepared in Example 3 is 2.3g / cm 3 The bending strength and absorption performance are 301.5±14.1MPa respectively, the minimum reflection loss value is -11.4dB, and the effective absorption bandwidth is 1.32GHz.

[0106] As demonstrated in the above examples, the prepared frequency-tunable multiphase reinforced polymer-derived absorbing ceramic composites exhibit excellent electromagnetic wave absorption and frequency-tunable properties, while also significantly improving mechanical properties. These materials achieve reflection losses below -10 dB across multiple frequency bands, with the lowest reflection loss exceeding -21 dB. Optimized absorption across different frequency bands can be achieved by adjusting the ratio of the components.

[0107] 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 principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A frequency-adjustable multiphase reinforced polymer-derived microwave-absorbing ceramic composite material, characterized in that: Calculated by volume percentage, it includes the following components: The polymer-derived ceramic matrix is ​​35-87%; the fiber is 10-40%; the fiber interface is 1-10%; the dielectric ceramic phase is 1-10%; and the ceramic hollow sphere is 1-5%.

2. The frequency-adjustable multiphase reinforced polymer-derived microwave-absorbing ceramic composite material according to claim 1, characterized in that: The polymer-derived ceramic matrix is ​​selected from one or more of polycarbosilane, polyborazane and polysilazane; The fiber is selected from one or more of carbon fiber, silicon carbide fiber, alumina fiber and glass fiber; The fiber interface is selected from one or more of a pyrolytic carbon interface, a boron nitride interface, and a silicon carbide interface; The dielectric ceramic phase is selected from one or more of bismuth ferrite, barium titanate, calcium bismuth niobate and lead zirconate titanate; the size of the dielectric ceramic phase is 50 to 500 nm; The hollow ceramic spheres are selected from one or more of hollow alumina spheres, hollow glass microspheres, hollow floating beads and hollow silicon carbide spheres, and the diameter of the hollow ceramic spheres is 10 to 100 μm.

3. A method for preparing the frequency-tunable multiphase reinforced polymer-derived microwave-absorbing ceramic composite material according to claim 1 or 2, comprising the following steps: Step 1) mixing dielectric ceramic powder, ceramic hollow balls, a binder, a dispersant, a plasticizer and a solvent, and ball milling to obtain a mixed ceramic slurry; Step 2), cutting the fiber cloth, removing the glue, and depositing the interface phase; Step 3), coating the fiber cloth obtained in step 2) with the mixed ceramic slurry obtained in step 1), then impregnating the fiber cloth, and drying the fiber cloth to obtain a fiber prepreg; Step 4) laminating the fiber prepreg sheets obtained in step 3) and vacuum sealing the layers, and curing them at a certain temperature and pressure to obtain a fiber preform; Step 5), debinding the fiber preform to obtain a fiber-reinforced multiphase ceramic preform; Step 6), vacuum-vibrating impregnation of the fiber-reinforced multiphase ceramic preform with a polymer-converted ceramic precursor and cracking the preform; Step 7) Repeat step 6) n times to obtain a frequency-adjustable multiphase reinforced polymer-derived microwave-absorbing ceramic composite material.

4. The preparation method according to claim 3, characterized in that The dispersant is selected from one or more of polyvinyl pyrrolidone, polyisobutylene and castor oil; The binder is selected from one or more of polyethylene glycol, polyvinyl butyral, phenolic resin and polymethyl methacrylate; The plasticizer is selected from one or more of methyl cellulose, dibutyl phthalate and polyvinyl acetate; The solvent is selected from one or more of anhydrous ethanol, xylene, methanol and gasoline.

5. The preparation method according to claim 3, characterized in that In step 2), the deposition temperature is 600-1100° C., and the deposition time is 100-1000 h; The thickness of the deposited interface phase is 0.1 to 2 μm.

6. The preparation method according to claim 3, characterized in that The impregnation method in step 3) is vacuum impregnation or vibration impregnation; The vacuum degree of the vacuum impregnation is -0.1 to -0.3 MPa, and the vacuum impregnation time is 2 to 12 hours; The frequency of the vibration impregnation is 40 to 120 kHz, and the time of the vibration impregnation is 0.5 to 12 hours; The drying temperature is 40-80°C, and the drying time is 120-900s.

7. The preparation method according to claim 3, characterized in that In step 4), the curing atmosphere is argon or nitrogen; the pressure is 100 to 1200 kPa, the curing temperature is 120 to 200° C., and the curing time is 1 to 4 hours; In step 5), the debinding atmosphere is a vacuum or inert atmosphere; the debinding temperature is 600-1200° C., and the debinding time is 1-4 hours.

8. The preparation method according to claim 3, characterized in that In step 6), the polymer is converted into a ceramic precursor to polyborazane, polycarbosilane or polysilazane; The cracking atmosphere is nitrogen or argon, the cracking temperature is 800-1200°C, and the cracking time is 0.5-6h.

9. The preparation method according to claim 3, characterized in that The number of deposition times n in step 7) is 5 to 12 times.

10. Use of the frequency-tunable multiphase reinforced polymer-derived microwave-absorbing ceramic composite material according to any one of claims 1 to 2 in aerospace, military equipment or electronic equipment.

Images