In-situ reaction and forming integrated method of wave-transparent composite material encapsulating wave-absorbing material
Patent Information
- Application Number
- CN202610993306.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-06
- Publication Date
- 2026-08-04
AI Technical Summary
[0005]本发明的目的是要解决现有方法制备吸波复合结构时，存在吸波功能层易脱落、制备工序复杂、吸波材料与复合材料基体结合不稳定，不能同时满足耐高温、透波防护、吸波衰减和结构承载使用要求的问题，而提供一种透波复合材料封装吸波材料原位反应及成形一体化方法
[0025]I. This invention utilizes hot pressing to achieve simultaneous integration of in-situ reaction of microwave absorbing material and encapsulation of composite substrate. The bonding and encapsulation of upper and lower substrates are completed while the precursor of microwave absorbing material is reacting, reducing the need for separate preparation of microwave absorbing layer, secondary bonding, and subsequent assembly processes.
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Figure CN122501027A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing a microwave absorbing material. Background Technology
[0002] In recent years, metal-organic framework (ZIF) materials and their derivatives have attracted widespread attention in the field of electromagnetic wave absorption due to their tunable composition, rich pore structure, high specific surface area, and ease of constructing multi-level structures. ZIF materials can be transformed into microwave absorbing materials containing metal oxides, metal / carbon composite phases, or porous carbon frameworks after heat treatment. Their porous structure facilitates multiple reflections and scattering of electromagnetic waves within the material, and the transition metal components can introduce magnetic loss, interfacial polarization, and impedance modulation, thereby improving the microwave absorption capability of the material. Introducing transition metal elements such as cobalt and manganese into ZIF systems allows for the production of Co / Mn-HD microwave absorbing materials with multi-shell hollow structures through compositional control and heat treatment processes. These materials combine the advantages of structural and compositional losses, making them suitable as lightweight and efficient microwave absorbing functional layers.
[0003] However, Co / Mn-ZIFs-derived multi-shell absorbing powders still suffer from problems in practical engineering applications, such as poor powder dispersion stability, sensitivity to external environments, difficulty in individual molding, and insufficient structural load-bearing capacity. If directly exposed as a coating or filler on the structural surface, they are prone to powder shedding, agglomeration, interface cracking, or degradation of absorption performance under conditions of humidity, heat, erosion, vibration, and thermal cycling. Therefore, it is necessary to use hot-pressing technology to stably encapsulate this type of absorbing powder inside a high-temperature resistant transparent composite material, allowing incident electromagnetic waves to pass through the outer transparent panel into the absorbing layer and be absorbed and attenuated in the middle Co / Mn-HD absorbing functional layer. At the same time, the outer composite material provides mechanical protection and environmental isolation for the absorbing powder.
[0004] Composite material microwave absorbing structures are mostly prepared using coatings, films, honeycomb sandwiches, or multi-layer bonding and curing methods. To address the fabrication of microwave-transparent composite structures, publication number CN111844939B proposes a three-layer microwave-transparent composite material and its preparation method; to address the issue of high-temperature resistant microwave absorbing structures, publication number CN107415336A proposes a multi-layer high-temperature resistant microwave absorbing structure based on a honeycomb structure; and to address the forming problem of complex-shaped microwave absorbing components, publication number CN113858656A proposes an integrated molding process for a sawtooth-shaped hollow composite material microwave absorbing component. While these methods can achieve microwave transmission, absorption, or structural load-bearing functions to a certain extent, their functional layers often rely on pre-fabricated films, honeycomb core materials, films, or secondary bonding. It is difficult to achieve in-situ reaction, densification, and simultaneous component forming of the absorbing medium between two layers of microwave-transparent composite thin plates, resulting in complex processes, insufficient interface reliability, susceptibility of the absorbing layer to environmental corrosion, and limited adaptability to complex curved surfaces. Summary of the Invention
[0005] The purpose of this invention is to solve the problems of easy detachment of the absorbing functional layer, complex preparation process, and unstable bonding between the absorbing material and the composite matrix when preparing absorbing composite structures using existing methods, which cannot simultaneously meet the requirements of high temperature resistance, wave transmission protection, wave absorption attenuation, and structural load-bearing. The invention provides an integrated method for in-situ reaction and forming of absorbing material encapsulated in a wave-transparent composite material.
[0006] An integrated method for in-situ reaction and forming of a wave-transparent composite material encapsulating a wave-absorbing material, specifically completed according to the following steps:
[0007] I. Substrate Pretreatment:
[0008] Two high-temperature resistant, wave-transparent composite material thin plates of the same size were selected as the upper and lower substrates. The upper and lower substrates were cleaned to remove oil, dust and impurities from the surface, and then dried to obtain the pretreated upper and lower substrates.
[0009] II. Preparation of precursors for cobalt / manganese-ZIFs microwave absorbing materials:
[0010] ① Dissolve manganese and cobalt salts in anhydrous methanol to obtain metal salt solutions;
[0011] ② Dissolve 2-methylimidazole in anhydrous methanol to obtain an organic ligand solution;
[0012] ③ Mix the metal salt solution and the organic ligand solution and let them stand to react. After the reaction is complete, centrifuge the reaction product, then wash and dry it to obtain the precursor of cobalt / manganese-ZIFs microwave absorbing material.
[0013] III. Laying up the precursor of the microwave absorbing material:
[0014] The cobalt / manganese-ZIFs microwave absorbing material precursor is uniformly laid on the surface of the pretreated lower substrate to obtain a lower substrate with a microwave absorbing material precursor layer.
[0015] IV. Laminated billet assembly:
[0016] The processed upper substrate is covered on the surface of the microwave absorbing material precursor layer, so that the microwave absorbing material precursor layer is located between the upper substrate and the lower substrate, resulting in a three-layer laminated blank of upper substrate / microwave absorbing material precursor layer / lower substrate.
[0017] V. Simultaneous processing of in-situ reaction and isothermal hot pressing:
[0018] Position the three-layer laminated blanks into a mold, and place the mold into an isothermal hot press. Perform constant temperature hot pressing or segmented heating hot pressing on the mold to allow the cobalt / manganese-ZIFs microwave absorbing material precursor to react in situ between the two substrates. At the same time, the upper substrate and the lower substrate are bonded, encapsulated and formed under the action of hot pressing to obtain a three-layer encapsulated microwave absorbing composite structure.
[0019] VI. Cooling and demolding:
[0020] Turn off the heating power supply, cool the mold to 30℃~60℃ while maintaining pressure, then unload the pressure and open the mold. Take out the formed three-layer encapsulated microwave absorbing composite structure from the mold to obtain a high-temperature resistant microwave transparent composite material encapsulated microwave absorbing sandwich structure. This completes an integrated method for in-situ reaction and forming of microwave transparent composite material encapsulated microwave absorbing material.
[0021] The principle of this invention:
[0022] To address the aforementioned problems, this invention proposes a method for the simultaneous and integrated in-situ reaction and hot-pressing of a high-temperature resistant, wave-transparent composite material for encapsulating a microwave-absorbing material. Hot-pressing encapsulation is performed concurrently with the in-situ reaction of the microwave-absorbing material precursor. The high-temperature resistant, wave-transparent composite material substrate serves as both the outer protective and load-bearing structure, allowing incident electromagnetic waves to pass through the outer substrate and enter the intermediate microwave-absorbing functional layer. The intermediate microwave-absorbing material is formed in-situ from a cobalt / manganese-ZIFs precursor during heating, possessing porous, multi-interface, core-shell, or hollow-shell structures, as well as cobalt-manganese bimetallic composition control characteristics. It can attenuate electromagnetic waves through dielectric loss, magnetic loss, interface polarization, multiple reflections, and scattering.
[0023] In this invention, the in-situ reaction of the microwave absorbing material precursor, the fixation of the microwave absorbing functional layer, and the hot-press encapsulation of the two composite material substrates are completed simultaneously in the same hot-press mold. This eliminates the need to pre-prepare the microwave absorbing material as an independent coating before secondary bonding, and also eliminates the need for complex subsequent assembly processes, thus shortening the manufacturing process and reducing manufacturing costs. Since the microwave absorbing functional layer is encapsulated between two high-temperature resistant microwave-transparent composite material substrates, the microwave absorbing powder is prevented from being directly exposed to the external environment, reducing problems such as powder shedding, moisture absorption, oxidation, erosion wear, and interface cracking, thereby improving the environmental stability and service reliability of the microwave absorbing composite structure. By adjusting the laying thickness of the microwave absorbing material precursor, the hot-pressing temperature, the heat preservation time, and the hot-pressing pressure, the structure of the microwave absorbing layer, the microwave absorbing frequency band, the microwave absorbing intensity, and the overall thickness of the composite structure can be controlled.
[0024] The present invention has the following beneficial effects:
[0025] I. This invention utilizes hot pressing to achieve simultaneous integration of in-situ reaction of microwave absorbing material and encapsulation of composite substrate. The bonding and encapsulation of upper and lower substrates are completed while the precursor of microwave absorbing material is reacting, reducing the need for separate preparation of microwave absorbing layer, secondary bonding, and subsequent assembly processes.
[0026] Second, the present invention uses a high-temperature resistant wave-transparent composite material thin plate as the outer substrate, which enables the incident electromagnetic waves to pass through the substrate and enter the middle wave-absorbing functional layer. At the same time, it plays a protective and load-bearing role for the wave-absorbing layer, which can reduce problems such as wave-absorbing powder shedding, moisture absorption, oxidation and erosion wear.
[0027] Third, this invention uses a cobalt / manganese-ZIFs microwave absorbing material precursor as the raw material for the intermediate functional layer. By adjusting the heating rate, reaction temperature and holding time, Co / Mn-HD microwave absorbing materials with different shell structure complexities can be obtained in situ, thereby improving electromagnetic wave loss and microwave absorption performance.
[0028] Fourth, this invention can achieve the preparation of three-layer encapsulated microwave absorbing composite structures with different thicknesses and different microwave absorbing performances by adjusting the thickness of the composite substrate, the thickness of the microwave absorbing layer, the hot pressing temperature, the heat preservation time, and the hot pressing pressure. The process is simple, the parameters are controllable, and the applicability is strong.
[0029] This invention provides a high-temperature resistant, wave-transparent composite material encapsulated wave-absorbing sandwich structure. Attached Figure Description
[0030] Figure 1 This is a schematic diagram of the process route for an integrated method of in-situ reaction and forming of a wave-transparent composite material for encapsulating a wave-absorbing material, according to the present invention.
[0031] Figure 2 This is a physical image of the high-temperature resistant, wave-transparent composite material encapsulated wave-absorbing sandwich structure prepared in Example 1;
[0032] Figure 3 This is a cross-sectional view of the high-temperature resistant, wave-transparent composite material encapsulated wave-absorbing sandwich structure prepared in Example 1. Detailed Implementation
[0033] The following embodiments further illustrate the content of the present invention, but should not be construed as limiting the present invention. Any modifications and substitutions made to the methods, steps, or conditions of the present invention without departing from the essence of the invention are within the scope of the present invention.
[0034] Specific Implementation Method 1: This implementation method is an integrated method for in-situ reaction and forming of microwave-transparent composite material encapsulating microwave-absorbing material, which is specifically completed according to the following steps:
[0035] I. Substrate Pretreatment:
[0036] Two high-temperature resistant, wave-transparent composite material thin plates of the same size were selected as the upper and lower substrates. The upper and lower substrates were cleaned to remove oil, dust and impurities from the surface, and then dried to obtain the pretreated upper and lower substrates.
[0037] II. Preparation of precursors for cobalt / manganese-ZIFs microwave absorbing materials:
[0038] ① Dissolve manganese and cobalt salts in anhydrous methanol to obtain metal salt solutions;
[0039] ② Dissolve 2-methylimidazole in anhydrous methanol to obtain an organic ligand solution;
[0040] ③ Mix the metal salt solution and the organic ligand solution and let them stand to react. After the reaction is complete, centrifuge the reaction product, then wash and dry it to obtain the precursor of cobalt / manganese-ZIFs microwave absorbing material.
[0041] III. Laying up the precursor of the microwave absorbing material:
[0042] The cobalt / manganese-ZIFs microwave absorbing material precursor is uniformly laid on the surface of the pretreated lower substrate to obtain a lower substrate with a microwave absorbing material precursor layer.
[0043] IV. Laminated billet assembly:
[0044] The processed upper substrate is covered on the surface of the microwave absorbing material precursor layer, so that the microwave absorbing material precursor layer is located between the upper substrate and the lower substrate, resulting in a three-layer laminated blank of upper substrate / microwave absorbing material precursor layer / lower substrate.
[0045] V. Simultaneous processing of in-situ reaction and isothermal hot pressing:
[0046] Position the three-layer laminated blanks into a mold, and place the mold into an isothermal hot press. Perform constant temperature hot pressing or segmented heating hot pressing on the mold to allow the cobalt / manganese-ZIFs microwave absorbing material precursor to react in situ between the two substrates. At the same time, the upper substrate and the lower substrate are bonded, encapsulated and formed under the action of hot pressing to obtain a three-layer encapsulated microwave absorbing composite structure.
[0047] VI. Cooling and demolding:
[0048] Turn off the heating power supply, cool the mold to 30℃~60℃ while maintaining pressure, then unload the pressure and open the mold. Take out the formed three-layer encapsulated microwave absorbing composite structure from the mold to obtain a high-temperature resistant microwave transparent composite material encapsulated microwave absorbing sandwich structure. This completes an integrated method for in-situ reaction and forming of microwave transparent composite material encapsulated microwave absorbing material.
[0049] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that: the high-temperature resistant and microwave-transparent composite material sheet mentioned in step one is one or two of polyetheretherketone (PEEK) sheets, thermoplastic polyimide sheets, fluorinated ethylene propylene copolymer sheets, and ethylene-tetrafluoroethylene copolymer sheets; the thickness of the high-temperature resistant and microwave-transparent composite material sheet mentioned in step one is 0.5 mm to 2 mm. Other steps are the same as in Specific Implementation Method One.
[0050] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that: the cleaning method described in step 1 is to wipe and clean the surfaces of the upper and lower substrates 1 to 3 times using anhydrous ethanol or acetone; the drying temperature described in step 1 is 80℃ to 100℃, and the drying time is 0.5h to 1h. Other steps are the same as in Specific Implementation Method 1 or 2.
[0051] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that: the manganese salt mentioned in step two ① is MnCl2·4H2O; and the cobalt salt is Co(NO3)2·6H2O. The other steps are the same as in Specific Implementation Methods One to Three.
[0052] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the molar ratio of manganese salt and cobalt salt in step two① is 1:1. The other steps are the same as in Specific Implementation Methods One to Four.
[0053] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: the amount of manganese salt in step two ① and the volume ratio of anhydrous methanol are 1 mmol: 4 mL; the amount of 2-methylimidazole in step two ② and the volume ratio of anhydrous methanol are (48 mmol~50 mmol): (25 mL~27 mL). The other steps are the same as in Specific Implementation Methods One to Five.
[0054] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that: the temperature for the static reaction described in step two ③ is room temperature, and the time is 10-12 hours; the washing described in step two ③ involves washing 3-5 times with anhydrous methanol. Other steps are the same as in Specific Implementation Methods One to Six.
[0055] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: in step three, the thickness of the absorbing material precursor layer on the surface of the lower substrate is 0.3mm to 0.8mm; in step four, the area of the absorbing material precursor layer is smaller than the areas of the upper and lower substrates, and a 5mm to 10mm encapsulation margin is maintained between the edge of the absorbing material precursor layer and the edges of the upper and lower substrates. Other steps are the same as in Specific Implementation Methods One to Seven.
[0056] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the isothermal hot pressing method described in step five is as follows: The mold is heated from room temperature to 340°C to 370°C at a heating rate of 15°C / min to 20°C / min. During the heating process, a pressure of 1kPa to 3kPa is applied, and the temperature and pressure are maintained at 1kPa to 3kPa for 0.5h to 1.5h, so that the cobalt / manganese-ZIFs microwave absorbing material precursor is converted in situ into Co / Mn-HD microwave absorbing material. The other steps are the same as in Specific Implementation Methods One to Eight.
[0057] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that the segmented heating and hot pressing method described in step five is as follows: In the first stage, the temperature is increased from room temperature to 250℃ to 280℃ at a heating rate of 0.5℃ / min to 1℃ / min, with a pressure of 1kPa to 3kPa applied during the heating process, and the temperature and pressure are maintained at 1kPa to 3kPa for 0.5h to 1.5h; in the second stage, the temperature is increased to 340℃ to 370℃ at a heating rate of 15℃ / min to 20℃ / min, with a pressure of 1kPa to 3kPa applied during the heating process, and the temperature and pressure are maintained at 1kPa to 3kPa for 0.5h, so that the cobalt / manganese-ZIFs microwave absorbing material precursor is converted in situ into Co / Mn-HD microwave absorbing material. Other steps are the same as in Specific Implementation Methods One to Nine.
[0058] The beneficial effects of the present invention are verified using the following embodiments:
[0059] Example 1: An integrated method for in-situ reaction and forming of microwave-absorbing materials encapsulated with microwave-transparent composite materials, characterized in that the method is specifically completed according to the following steps:
[0060] I. Substrate Pretreatment:
[0061] Two polyetheretherketone (PEEK) sheets, each 0.5 mm thick, were selected as the upper and lower substrates. The surfaces of the upper and lower substrates were wiped and cleaned twice with acetone and anhydrous ethanol, respectively, to remove oil, dust and impurities. The substrates were then dried at 80°C for 1 hour to obtain the pretreated upper and lower substrates.
[0062] II. Preparation of precursors for cobalt / manganese-ZIFs microwave absorbing materials:
[0063] ① Dissolve 1 mmol MnCl2·4H2O and 1 mmol Co(NO3)2·6H2O in 4 mL of anhydrous methanol, and disperse them evenly by ultrasonication to obtain a metal salt solution;
[0064] ② Dissolve 49.91 mmol of 2-methylimidazole in 26 mL of anhydrous methanol to obtain an organic ligand solution;
[0065] ③ Mix the metal salt solution and the organic ligand solution and let them stand at 25°C for 11 hours. After the reaction is complete, the reaction product is centrifuged, washed three times with anhydrous methanol, and finally dried to obtain the precursor of cobalt / manganese-ZIFs microwave absorbing material.
[0066] The purpose of forming the cobalt / manganese-ZIFs microwave absorbing material precursor in step two is to obtain a cobalt-manganese bimetallic organic framework structure. The main reaction process is as follows:
[0067] Co 2+ + Mn 2+ + 2-Methylimidazole → Co / Mn-ZIFs;
[0068] III. Laying up the precursor of the microwave absorbing material:
[0069] The cobalt / manganese-ZIFs microwave absorbing material precursor is uniformly laid on the surface of the pretreated lower substrate to obtain a lower substrate with a microwave absorbing material precursor layer.
[0070] In step three, the thickness of the microwave absorbing material precursor layer on the surface of the lower substrate is 0.5mm; the laying method is scraper laying; the laying area of the microwave absorbing material precursor layer is smaller than the area of the upper substrate and the lower substrate, and a 5mm encapsulation margin is maintained between the edge of the microwave absorbing material precursor layer and the edge of the substrate.
[0071] IV. Laminated billet assembly:
[0072] The processed upper substrate is covered on the surface of the microwave absorbing material precursor layer, so that the microwave absorbing material precursor layer is located between the upper substrate and the lower substrate, resulting in a three-layer laminated blank of upper substrate / microwave absorbing material precursor layer / lower substrate.
[0073] V. Simultaneous processing of in-situ reaction and isothermal hot pressing:
[0074] The three-layer laminated blank is positioned and molded, and the mold is placed in an isothermal hot press. The mold is heated and hot pressed in stages to make the cobalt / manganese-ZIFs microwave absorbing material precursor react in situ between the two substrates. At the same time, the upper substrate and the lower substrate are bonded, encapsulated and formed under the action of hot pressing to obtain a three-layer encapsulated microwave absorbing composite structure.
[0075] The segmented heating and hot pressing method described in step five is as follows: In the first stage, the temperature is increased from room temperature to 270°C at a heating rate of 0.5°C / min, and a pressure of 2 kPa is applied during the heating process. The temperature and pressure are maintained at 2 kPa for 1 hour. In the second stage, the temperature is increased to 360°C at a heating rate of 20°C / min, and a pressure of 2 kPa is applied during the heating process. The temperature and pressure are maintained at 2 kPa for 0.5 hours. This allows the cobalt / manganese-ZIFs microwave absorbing material precursor to be converted in situ into Co / Mn-HD microwave absorbing material, while simultaneously completing the hot pressing encapsulation between the upper and lower substrates.
[0076] VI. Cooling and demolding:
[0077] Turn off the heating power, cool the mold to 50°C while maintaining pressure, then unload the pressure and open the mold. Remove the formed three-layer encapsulated microwave absorbing composite structure from the mold to obtain a high-temperature resistant microwave transparent composite material encapsulated microwave absorbing sandwich structure. This completes an integrated method for in-situ reaction and forming of microwave transparent composite material encapsulated microwave absorbing material.
[0078] The purpose of the in-situ reaction described in step five of Example 1 is to transform the cobalt / manganese-ZIFs microwave absorbing material precursor into Co / Mn-HD microwave absorbing material between two polyimide-based composite material substrates, while simultaneously fixing the microwave absorbing functional layer and encapsulating the composite material substrate. The purpose of the hot pressing is to achieve bonding, sealing, and integral forming of the upper and lower substrates under pressure, thereby obtaining a three-layer encapsulated microwave absorbing composite structure.
[0079] Figure 1 This is a schematic diagram of the process route for an integrated method of in-situ reaction and forming of a wave-transparent composite material for encapsulating a wave-absorbing material, according to the present invention.
[0080] from Figure 1 As can be seen from the above, the high-temperature resistant wave-transparent composite material encapsulated wave-absorbing sandwich structure prepared in Example 1 consists of an upper polyimide-based composite material substrate, a middle Co / Mn-HD wave-absorbing functional layer, and a lower polyimide-based composite material substrate. The middle wave-absorbing functional layer is stably encapsulated between the two substrates.
[0081] Figure 2 This is a physical image of the high-temperature resistant, wave-transparent composite material encapsulated wave-absorbing sandwich structure prepared in Example 1;
[0082] from Figure 2 As can be seen from the above, the surface of the high-temperature resistant wave-transparent composite material encapsulated wave-absorbing sandwich structure prepared in Example 1 is flat, the edge encapsulation is complete, and there is no obvious warping, cracking or powder overflow.
[0083] Figure 3 This is a cross-sectional view of the high-temperature resistant, wave-transparent composite material encapsulated wave-absorbing sandwich structure prepared in Example 1;
[0084] from Figure 3 As can be seen from the data, the high-temperature resistant, microwave-transparent composite material encapsulated microwave-absorbing sandwich structure prepared in Example 1 consists of an upper polyetheretherketone (PEEK) sheet, a middle Co / Mn-HD microwave-absorbing functional layer, and another PEEK sheet. The middle microwave-absorbing functional layer is stably encapsulated between the two substrates. Furthermore, the upper and lower substrates and the middle microwave-absorbing functional layer are tightly bonded in the cross-section of the high-temperature resistant, microwave-transparent composite material encapsulated microwave-absorbing sandwich structure. The thickness of the microwave-absorbing functional layer is relatively uniform, and no obvious delamination, voids, or powder accumulation defects are observed.
[0085] The total thickness of the high-temperature resistant, wave-transparent composite material encapsulated microwave-absorbing sandwich structure prepared in Example 1 is approximately 1.5 mm.
Claims
1. A method for in-situ reaction and forming of wave-absorbing material encapsulated by wave-transparent composite material, characterized in that This method is specifically completed in the following steps: I. Substrate Pretreatment: Two high-temperature resistant, wave-transparent composite material thin plates of the same size were selected as the upper and lower substrates. The upper and lower substrates were cleaned to remove oil, dust and impurities from the surface, and then dried to obtain the pretreated upper and lower substrates. II. Preparation of precursors for cobalt / manganese-ZIFs microwave absorbing materials: ① Dissolve manganese and cobalt salts in anhydrous methanol to obtain metal salt solutions; ② Dissolve 2-methylimidazole in anhydrous methanol to obtain an organic ligand solution; ③ Mix the metal salt solution and the organic ligand solution and let them stand to react. After the reaction is complete, centrifuge the reaction product, then wash and dry it to obtain the precursor of cobalt / manganese-ZIFs microwave absorbing material. III. Laying up the precursor of the microwave absorbing material: The cobalt / manganese-ZIFs microwave absorbing material precursor is uniformly laid on the surface of the pretreated lower substrate to obtain a lower substrate with a microwave absorbing material precursor layer. IV. Laminated billet assembly: The processed upper substrate is covered on the surface of the microwave absorbing material precursor layer, so that the microwave absorbing material precursor layer is located between the upper substrate and the lower substrate, resulting in a three-layer laminated blank of upper substrate / microwave absorbing material precursor layer / lower substrate. V. Simultaneous processing of in-situ reaction and isothermal hot pressing: Position the three-layer laminated blanks into a mold, and place the mold into an isothermal hot press. Perform constant temperature hot pressing or segmented heating hot pressing on the mold to allow the cobalt / manganese-ZIFs microwave absorbing material precursor to react in situ between the two substrates. At the same time, the upper substrate and the lower substrate are bonded, encapsulated and formed under the action of hot pressing to obtain a three-layer encapsulated microwave absorbing composite structure. VI. Cooling and demolding: Turn off the heating power supply, cool the mold to 30℃~60℃ while maintaining pressure, then unload the pressure and open the mold. Take out the formed three-layer encapsulated microwave absorbing composite structure from the mold to obtain a high-temperature resistant microwave transparent composite material encapsulated microwave absorbing sandwich structure. This completes an integrated method for in-situ reaction and forming of microwave transparent composite material encapsulated microwave absorbing material.
2. The integrated method for in-situ reaction and forming of a wave-transparent composite material encapsulating a wave-absorbing material according to claim 1, characterized in that... The high-temperature resistant and microwave-transparent composite material sheet mentioned in step one is one or two of polyetheretherketone sheet, thermoplastic polyimide sheet, fluorinated ethylene propylene copolymer sheet, and ethylene-tetrafluoroethylene copolymer sheet; the thickness of the high-temperature resistant and microwave-transparent composite material sheet mentioned in step one is 0.5mm~2mm.
3. The integrated method for in-situ reaction and forming of a wave-transparent composite material encapsulating a wave-absorbing material according to claim 1, characterized in that... The cleaning method described in step one is as follows: wipe and clean the surfaces of the upper and lower substrates 1 to 3 times with anhydrous ethanol or acetone; the drying temperature described in step one is 80℃ to 100℃, and the drying time is 0.5h to 1h.
4. The integrated method for in-situ reaction and forming of a wave-transparent composite material encapsulating a wave-absorbing material according to claim 1, characterized in that... The manganese salt mentioned in step 2① is MnCl2·4H2O; the cobalt salt is Co(NO3)2·6H2O.
5. The integrated method for in-situ reaction and forming of a wave-transparent composite material encapsulating a wave-absorbing material according to claim 1, characterized in that... The molar ratio of manganese salt and cobalt salt mentioned in step 2① is 1:
1.
6. The integrated method for in-situ reaction and forming of a wave-transparent composite material encapsulating a wave-absorbing material according to claim 1, characterized in that... In step 2①, the amount of manganese salt and the volume ratio of anhydrous methanol are 1 mmol: 4 mL; in step 2②, the amount of 2-methylimidazole and the volume ratio of anhydrous methanol are (48 mmol~50 mmol): (25 mL~27 mL).
7. The integrated method for in-situ reaction and forming of a wave-transparent composite material encapsulating a wave-absorbing material according to claim 1, characterized in that... The static reaction described in step 2.③ is carried out at room temperature for 10-12 hours; the washing described in step 2.③ is washing with anhydrous methanol 3-5 times.
8. The integrated method for in-situ reaction and forming of a wave-transparent composite material encapsulating a wave-absorbing material according to claim 1, characterized in that... In step three, the thickness of the absorbing material precursor layer on the surface of the lower substrate is 0.3mm to 0.8mm; in step four, the area of the absorbing material precursor layer is smaller than the area of the upper and lower substrates, and a 5mm to 10mm encapsulation margin is maintained between the edge of the absorbing material precursor layer and the edges of the upper and lower substrates.
9. The integrated method for in-situ reaction and forming of a wave-transparent composite material encapsulating a wave-absorbing material according to claim 1, characterized in that... The isothermal hot pressing method described in step five is as follows: the mold is heated from room temperature to 340℃~370℃ at a heating rate of 15℃ / min~20℃ / min. During the heating process, a pressure of 1kPa~3kPa is applied, and the temperature and pressure are maintained at 1kPa~3kPa for 0.5h~1.5h, so that the cobalt / manganese-ZIFs microwave absorbing material precursor is converted into Co / Mn-HD microwave absorbing material in situ.
10. The integrated method for in-situ reaction and forming of a wave-transparent composite material encapsulating a wave-absorbing material according to claim 1, characterized in that... The segmented heating and hot pressing method described in step five is as follows: In the first stage, the temperature is increased from room temperature to 250℃ to 280℃ at a heating rate of 0.5℃ / min to 1℃ / min, and a pressure of 1kPa to 3kPa is applied during the heating process. The temperature and pressure are maintained at 1kPa to 3kPa for 0.5h to 1.5h. In the second stage, the temperature is increased to 340℃ to 370℃ at a heating rate of 15℃ / min to 20℃ / min, and a pressure of 1kPa to 3kPa is applied during the heating process. The temperature and pressure are maintained at 1kPa to 3kPa for 0.5h, so that the cobalt / manganese-ZIFs microwave absorbing material precursor is converted into Co / Mn-HD microwave absorbing material in situ.