A high-temperature-resistant wave-absorbing honeycomb component and a preparation method thereof

Abstract

This invention relates to the field of microwave absorbing materials technology, and particularly to a high-temperature resistant microwave absorbing honeycomb component and its preparation method. An embodiment of this invention provides a method for preparing a high-temperature resistant microwave absorbing honeycomb component, comprising: S1, preparing a preliminary microwave absorbing honeycomb sample using glass fiber cloth impregnated with polyimide resin; S2, mixing carbon black, polyimide resin, solvent, and additives to obtain an absorbing slurry; S3, spraying the absorbing slurry onto the preliminary microwave absorbing honeycomb sample and curing it to obtain an absorbing honeycomb; S4, preparing a skin prepreg using glass fiber cloth impregnated with polyimide resin; S5, using the microwave absorbing honeycomb as a anolyte, layering the skin prepreg onto its surface, and curing it to obtain the high-temperature resistant microwave absorbing honeycomb component. This invention provides a high-temperature resistant microwave absorbing honeycomb component and its preparation method, which can be used at a high temperature of 350°C.

Description

Technical Field

[0001] This invention relates to the field of microwave absorbing materials technology, and in particular to a high-temperature resistant microwave absorbing honeycomb component and its preparation method. Background Technology

[0002] As future targets achieve increasingly higher speeds, the problem of rising surface temperatures due to aerodynamic heating becomes more severe. With further increases in target load ratio requirements, lightweight, high-strength, and microwave-absorbing composite materials are being used in more and more parts of the airframe structure. These applications place higher demands on the temperature resistance of composite materials, typically requiring material systems to withstand long-term operation at 350°C. Therefore, resin-based microwave-absorbing composite materials with high-temperature resistance are key materials for new high-speed targets.

[0003] Honeycomb absorbing structures have been widely used in the aerospace field due to their unique shape and load-bearing characteristics. Because of their special shape, electromagnetic waves can be reflected and absorbed multiple times on the inner and outer walls, making them a natural microwave absorbing shape. Currently, absorbing honeycomb structures mainly use aramid fibers as the substrate, with carbon black as the absorbing component attached to the inner and outer walls, serving the dual function of carrying and absorbing electromagnetic waves. Aramid fibers typically have a maximum temperature resistance of around 200℃, while epoxy resin typically has a temperature resistance of 180℃. Commonly used aramid / epoxy resin honeycomb absorbing structures will experience expansion, deformation, and a sharp drop in mechanical properties when exceeding their temperature resistance, making them unsuitable for use under higher temperature conditions.

[0004] For high-temperature resistant structural microwave absorbing composite materials, related research mainly focuses on the technological development of high-temperature resistant resin-based composite systems, high-temperature resistant absorbent systems, and high-temperature resistant honeycomb systems. At the same time, due to the more prominent interface problems between reinforcing fibers and resin matrices at high temperatures, various high-performance thermosetting resins, while possessing their own advantages, all have some shortcomings in monomer synthesis, molding processes, and mechanical properties. The most significant is insufficient heat resistance, especially for resins such as epoxy, bismaleimide, benzoxazine, and cyanate esters, whose heat resistance needs further improvement. Polyarylene acetylene can withstand temperatures exceeding 400℃, but the poor interfacial bonding between this resin and fibers results in poor mechanical properties of its composites, making it unsuitable as a matrix resin for structural composite materials.

[0005] In conclusion, it is urgent to develop a method for fabricating components based on 350℃-resistant absorbing honeycomb. Summary of the Invention

[0006] This invention provides a high-temperature resistant absorbing honeycomb component and its preparation method, which can be used at a high temperature of 350°C.

[0007] In a first aspect, embodiments of the present invention provide a method for preparing a high-temperature resistant absorbing honeycomb component, comprising: S1, a preliminary sample of a microwave absorbing honeycomb was prepared using glass fiber cloth impregnated with polyimide resin; S2, mix carbon black, polyimide resin, solvent and additives to obtain microwave absorbing paste; S3, the microwave absorbing paste is sprayed onto the microwave absorbing honeycomb prototype and cured to obtain the microwave absorbing honeycomb; S4, using glass fiber cloth impregnated with polyimide resin to prepare skin prepreg; S5, using the absorbing honeycomb as a positive membrane, the skin prepreg is laid on its surface and cured to obtain a high-temperature resistant absorbing honeycomb component.

[0008] Optionally, S1 includes: S101, glass fiber cloth is impregnated in polyimide resin to obtain a microwave absorbing honeycomb substrate; S102, the microwave absorbing honeycomb substrate is coated with polyimide node adhesive at intervals, stacked at preset intervals, and placed in a flatbed hot press for curing to obtain a preliminary microwave absorbing honeycomb sample.

[0009] Optionally, in S101, the viscosity of the polyimide resin is adjusted to 125±5 CPS by mixing it with ethanol; After impregnation, the temperature is raised in an oven at a rate of 1~3℃ / min to 375±5℃, held for 150min, and then cooled down in the oven to obtain the microwave absorbing honeycomb substrate.

[0010] Optionally, in S102, the viscosity of the joint adhesive is adjusted to 225±5 CPS; The curing process using a flatbed hot press includes: At room temperature, the pressure is 8~12 MPa; After pre-pressurization, the temperature is increased in the hot press at a rate of 1~3℃ / min. After reaching 350±5℃, the pressure is increased to 0.6±0.05MPa. During the pressurization process, the temperature is increased at a rate of 1~3℃ / min to 375±5℃. The temperature is held for 150min. The pressure is released and the product is removed when the temperature drops below 60℃.

[0011] Optionally, after obtaining the initial absorbing cell sample, the method further includes: The process of stretching the high-temperature resistant microwave absorbing honeycomb prototype involves simultaneously stretching and shaping the prototype to ensure that the cells can be evenly expanded. After stretching, immerse it in a polyimide solution with a viscosity of 125±5 CPS. After no excess liquid remains, let it stand for 15~20 minutes. Repeat the immersion and standing process several times. After impregnation, place the product in an oven for heat treatment, heating at a rate of 1~3℃ / min until it reaches 375±5℃, hold for 150min, and then cool down with the oven.

[0012] Optionally, in S2, the ratio of carbon black, polyimide resin, solvent and additives is (8~12):(50~60):(10:20):(8~10).

[0013] Optionally, in S3, after the spraying is completed, the product is placed in an oven for heat treatment, heated at a rate of 1~3℃ / min to 375±5℃, held for 150min, and then cooled down with the oven.

[0014] Optionally, step S4 includes: The viscosity of the polyimide resin was adjusted to 125±5 CPS. The polyimide resin was impregnated onto the surface of the glass fiber cloth using an impregnation device. The mixture was heated at 80~100℃ for 1 hour and the solvent was dried to obtain the polyimide glass fiber prepreg.

[0015] Optionally, pressure curing in S5 includes: The temperature was increased at a rate of 1~3℃ / min, and after reaching 350±5℃, the pressure was increased to 1.5±0.02MPa. During the pressurization process, the temperature continues to rise to 375±5℃ at a rate of 1~3℃ / min, and is held at that temperature for 150min; After the heat preservation is completed, the pressure is reduced and the temperature drops to 60℃. The vacuum is then released, and the high-temperature resistant microwave absorbing honeycomb component is obtained after demolding.

[0016] Secondly, embodiments of the present invention provide a high-temperature resistant absorbing honeycomb component, which is prepared according to any of the above-described preparation methods.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects: This invention provides a method for preparing a component based on a 350℃-resistant absorbing honeycomb structure. The method involves impregnating a high-temperature resistant glass fiber cloth with a high-temperature resistant polyimide resin to obtain a high-temperature resistant absorbing honeycomb component with a high degree of interfacial bonding. This component can operate at 350℃ for an extended period (at least 15 minutes) and its scattering characteristics control performance is similar at both room temperature and 350℃, which is a significant improvement over a metal component of the same shape.

[0018] This invention uses a reinforced honeycomb core as the positive membrane, eliminating the need for molds in the manufacturing process, making raw material costs controllable, simplifying the preparation process, and providing a highly versatile method that can be applied to the production of other components. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 These are test photos of the components from Example 1; Figure 2 These are test photos of components from Example 2; Figure 3 These are the RCS curves of Example 1 at 3GHz in metallic state, at room temperature, and at 350℃; Figure 4 These are the RCS curves of Example 1 at 10GHz in metallic state, at room temperature, and at 350℃. Figure 5 These are the RCS curves for the 3GHz Example 2 in its metallic state, at room temperature, and at 350°C. Figure 6 The RCS curves for the 10GHz Example 2 are in the metallic state, at room temperature, and at 350°C. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] This invention provides a method for preparing a high-temperature resistant absorbing honeycomb component, comprising: S1, a preliminary sample of a microwave absorbing honeycomb was prepared using glass fiber cloth impregnated with polyimide resin; S2, mix carbon black, polyimide resin, solvent and additives to obtain microwave absorbing paste; S3, the microwave absorbing paste is sprayed onto the microwave absorbing honeycomb prototype and cured to obtain the microwave absorbing honeycomb; S4, using glass fiber cloth impregnated with polyimide resin to prepare skin prepreg; S5, using the absorbing honeycomb as a positive membrane, the skin prepreg is laid on its surface and cured to obtain a high-temperature resistant absorbing honeycomb component.

[0023] In this embodiment, the method for manufacturing the high-temperature resistant absorbing honeycomb component has the following characteristics: Standardized materials: The use of a full polyimide system ensures compatibility of the thermophysical properties of each component.

[0024] Refined process: In the curing process of different steps, the flow, wetting and reaction of resin are precisely controlled by the curing curve of graded heating and selective pressure, so as to minimize residual stress and promote the formation of a strong interface.

[0025] Structural integration: The interface is reinforced by multiple impregnations and then co-cured to form a "seamless" stable structure from the fiber, resin, honeycomb, skin and microwave absorbing layer, which can withstand high temperature tests together.

[0026] In some embodiments of the present invention, S1 includes: S101, glass fiber cloth is impregnated in polyimide resin to obtain a microwave absorbing honeycomb substrate; S102, the microwave absorbing honeycomb substrate is coated with polyimide node adhesive at intervals, stacked at preset intervals, and placed in a flatbed hot press for curing to obtain a preliminary microwave absorbing honeycomb sample.

[0027] In some embodiments of the present invention, in S101, the viscosity of the polyimide resin is adjusted to 125±5 CPS by mixing it with ethanol; After impregnation, the temperature is raised in an oven at a rate of 1~3℃ / min to 375±5℃, held for 150min, and then cooled down in the oven to obtain the microwave absorbing honeycomb substrate.

[0028] In some embodiments of the present invention, in S102, the viscosity of the joint adhesive is adjusted to 225±5 CPS; The curing process using a flatbed hot press includes: At room temperature, the pressure is 8~12 MPa; After pre-pressurization, the temperature is increased in the hot press at a rate of 1~3℃ / min. After reaching 350±5℃, the pressure is increased to 0.6±0.05MPa. During the pressurization process, the temperature is increased at a rate of 1~3℃ / min to 375±5℃. The temperature is held for 150min. The pressure is released and the product is removed when the temperature drops below 60℃.

[0029] In some embodiments of the present invention, after obtaining the initial absorbing honeycomb sample, the method further includes: The process of stretching the high-temperature resistant microwave absorbing honeycomb prototype involves simultaneously stretching and shaping the prototype to ensure that the cells can be evenly expanded. After stretching, immerse it in a polyimide solution with a viscosity of 125±5 CPS. After no excess liquid remains, let it stand for 15~20 minutes. Repeat the immersion and standing process several times. After impregnation, place the product in an oven for heat treatment, heating at a rate of 1~3℃ / min until it reaches 375±5℃, hold for 150min, and then cool down with the oven.

[0030] In some embodiments of the present invention, in S2, the ratio of carbon black, polyimide resin, solvent and additives is (8~12):(50~60):(10:20):(8~10).

[0031] In some embodiments of the present invention, in step S3, after the spraying is completed, the product is placed in an oven for heat treatment, heated at a rate of 1~3℃ / min to 375±5℃, held at that temperature for 150min, and then cooled down with the oven.

[0032] In some embodiments of the present invention, step S4 includes: The viscosity of the polyimide resin was adjusted to 125±5 CPS. The polyimide resin was impregnated onto the surface of the glass fiber cloth using an impregnation device. The mixture was heated at 80~100℃ for 1 hour and the solvent was dried to obtain the polyimide glass fiber prepreg.

[0033] In some embodiments of the present invention, pressure curing in S5 includes: The temperature was increased at a rate of 1~3℃ / min, and after reaching 350±5℃, the pressure was increased to 1.5±0.02MPa. During the pressurization process, the temperature continues to rise to 375±5℃ at a rate of 1~3℃ / min, and is held at that temperature for 150min; After the heat preservation is completed, the pressure is reduced and the temperature drops to 60℃. The vacuum is then released, and the high-temperature resistant microwave absorbing honeycomb component is obtained after demolding.

[0034] This invention provides a high-temperature resistant absorbing honeycomb component, which is prepared according to any of the above-described preparation methods.

[0035] To more clearly illustrate the technical solution and advantages of the present invention, several embodiments are described in detail below.

[0036] Example 1 A method for fabricating a component based on a 350℃ heat-absorbing honeycomb structure, for manufacturing the leading edge of an airfoil, includes the following steps: S1. Based on the specifications of 1000*1000*50mm, the core material is selected as plain fiberglass cloth with a single sheet thickness of 0.2mm. The blank is free from excessive deformation, damage, stains, and excess material. Take the polyimide resin out of the cold storage and thaw it for more than 6 hours. Dissolve it in a clean container with industrial ethanol and adjust the viscosity to 125 CPS. Impregnate the plain fiberglass cloth in the polyimide resin once. After no excess liquid remains, let it stand for 20 minutes and put it into an oven for heat treatment. The temperature is increased at a rate of (1~3)℃ / min to (375±5)℃ and held for 150 minutes. Then, the temperature is lowered with the oven to obtain a microwave absorbing honeycomb substrate with preliminary strength. S2. Adjust the viscosity of the polyimide resin to 225±5 CPS and set aside. According to the specifications and dimensions of the laminate, set the corresponding parameters of the glue applicator and select a 2.75mm grid glue applicator roller. Install the microwave absorbing honeycomb substrate obtained in S1 on the glue applicator's feeding bracket, add the adjusted viscosity polyimide resin to the glue tank, turn on the glue applicator, and complete the node adhesive coating. After coating, place at room temperature for 8-10 hours. Once the solvent has evaporated and the adhesive is slightly viscous, stack the fiberglass honeycomb core material laminates on the stacking board in an alternating pattern according to the honeycomb dimensions. The laminated fiberglass honeycomb core material laminates are then pre-pressed using a multi-layer hot press. The pre-pressing process is as follows: at room temperature, the pressure is 8-12 MPa. After pre-pressing, the temperature is increased in the hot press at a rate of (1-3)℃ / min until it reaches (350±5)℃. Then, the pressure is increased to (0.6±0.05) MPa. During the pressurization process, the temperature continues to increase at a rate of (1-3)℃ / min until it reaches (375±5)℃. The temperature is maintained for 150 minutes. Once the temperature drops below 60℃, the pressure is released and the laminates are removed. S3. Fix both ends of the laminated plate to the two sides of the stretching beam of the honeycomb stretching machine. Start the stretching machine and gradually stretch the glass fiber honeycomb core material. During the stretching process, observe the honeycomb lattice and adjust the shape while stretching to ensure that the lattice can be evenly expanded. After stretching, immerse it in a polyimide solution with a viscosity of 125±5 CPS. After no excess liquid remains, let it stand for 15~20 minutes as one immersion. Repeat the immersion three times. After immersion, place it in an oven for heat treatment. Increase the temperature at a rate of (1~3)℃ / min to (375±5)℃, hold for 150 minutes, and then cool down with the oven to obtain a reinforced high-temperature resistant absorbing honeycomb substrate. S4. Weigh 800g carbon black, 6000g polyimide resin, 1000g anhydrous ethanol, 800g n-butanol and xylene mixture, stir mechanically for 30min at 800r / min, and after stirring, grind twice using a three-roll mill. S5. Using air spraying, the microwave absorbing slurry prepared in S4 is evenly sprayed onto the microwave absorbing honeycomb. One orthogonal layer is applied to each side, and two layers are applied to each side. After spraying, the honeycomb is placed in an oven for heat treatment. The temperature is increased at a rate of (1~3)℃ / min to (375±5)℃, and held for 150min. Then, the temperature is lowered with the oven to obtain a reinforced high-temperature resistant microwave absorbing honeycomb. S6. Cut the absorbing honeycomb according to the component's external dimensions. The cutting size of the absorbing honeycomb should be the target size minus the skin size and then minus the estimated deformation. The skin thickness is 2mm, the deformation is 1mm, and the cutting allowance is 3mm. S7. Adjust the viscosity of the polyimide resin to 125±5CPS, use an impregnation device to impregnate the polyimide resin onto the surface of the glass fiber cloth, heat at 80℃ for 1 hour, and dry the solvent to obtain polyimide glass fiber prepreg. S8. Cut the polyimide fiberglass cloth prepreg according to the size requirements. Use the cut microwave absorbing honeycomb as the positive film. Lay the prepreg onto the surface of the microwave absorbing honeycomb with a thickness of 2mm. Place it in an autoclave for heating and pressurization according to the resin curing conditions. Increase the temperature at a rate of (1~3)℃ / min. After reaching (350±5)℃, start pressurizing to (1.5±0.02)MPa. During the pressurization process, continue to increase the temperature at a rate of (1~3)℃ / min to (375±5)℃ and hold for 150min. After the heat preservation is completed, start depressurizing. When the temperature drops to 60℃, release the vacuum. After demolding, the high-temperature resistant microwave absorbing honeycomb wing leading edge is obtained.

[0037] The completed component in Example 1 is as follows Figure 1 As shown, the component was loaded onto the carrier for RCS testing, and the test results are as follows. Figure 3 and Figure 4 As shown, at 3 GHz, the average RCS in the metallic state is -14.527 dBsm, in the room-temperature absorbing state it is -19.771 dBsm, and after baking at 350°C it is -20.221 dBsm. The component's scattering characteristic control performance at room temperature and 350°C is similar, showing a significant improvement over the metallic state with the same shape. At 10 GHz, the average RCS in the metallic state is -13.603 dBsm, in the room-temperature absorbing state it is -17.866 dBsm, and after baking at 350°C it is -18.042 dBsm. The component's scattering characteristic control performance at room temperature and 350°C is similar, showing a significant improvement over the metallic state with the same shape.

[0038] Example 2 A method for fabricating a component based on a 350℃ heat-absorbing honeycomb structure, comprising the following steps: S1. Based on the specifications of 1500*1500*50mm, the core material is selected as glass fiber plain weave cloth with a single sheet thickness of 0.2mm. The blank is free from excessive deformation, damage, stains, and excess material. Take the polyimide resin out of the cold storage and thaw it for more than 6 hours. Dissolve it in a clean container with industrial ethanol and adjust the viscosity to 125±5CPS. Impregnate the glass fiber plain weave cloth in the polyimide resin. After no excess liquid remains, let it stand for 15~20min. Place it in an oven for heat treatment, raise the temperature at a rate of (1~3)℃ / min to (375±5)℃, hold for 150min, and then cool it down with the oven to obtain a microwave absorbing honeycomb substrate with preliminary strength. S2. Adjust the viscosity of the polyimide resin to 225±5 CPS and set aside. According to the specifications and dimensions of the laminate, set the corresponding parameters of the glue applicator and select a 3.67mm grid glue applicator roller. Install the microwave absorbing honeycomb substrate obtained in S1 on the glue applicator's feeding bracket, add the adjusted viscosity of the polyimide resin to the glue tank, turn on the glue applicator, and complete the node adhesive coating. After coating, place at room temperature for 8-10 hours. Once the solvent has evaporated and the adhesive is slightly viscous, stack the fiberglass honeycomb core material laminates on the stacking board in an alternating pattern according to the honeycomb dimensions. The laminated fiberglass honeycomb core material laminates are then pre-pressed using a multi-layer hot press. The pre-pressing process is as follows: at room temperature, the pressure is 8-12 MPa. After pre-pressing, the temperature is increased in the hot press at a rate of (1-3)℃ / min until it reaches (350±5)℃. Then, the pressure is increased to (0.6±0.05) MPa. During the pressurization process, the temperature continues to increase at a rate of (1-3)℃ / min until it reaches (375±5)℃. The temperature is maintained for 150 minutes. Once the temperature drops below 60℃, the pressure is released and the laminates are removed. S3. Fix both ends of the laminated plate to the two sides of the stretching beam of the honeycomb stretching machine. Start the stretching machine and gradually stretch the glass fiber honeycomb core material. During the stretching process, observe the honeycomb lattice and adjust the shape while stretching to ensure that the lattice can be evenly expanded. After stretching, immerse it in a polyimide solution with a viscosity of 125±5 CPS. After no excess liquid remains, let it stand for 15~20 minutes as one immersion. Repeat the immersion three times. After immersion, place it in an oven for heat treatment. Increase the temperature at a rate of (1~3)℃ / min to (375±5)℃, hold for 150 minutes, and then cool down with the oven to obtain a reinforced high-temperature resistant absorbing honeycomb substrate. S4. Weigh 1500g carbon black, 9000g polyimide resin, 1500g anhydrous ethanol, 1500g n-butanol and xylene mixture, stir mechanically for 30min at 1000r / min, and after stirring, grind twice using a three-roll mill. S5. Using air spraying, the microwave absorbing slurry prepared in S4 is evenly sprayed onto the microwave absorbing honeycomb. One orthogonal layer is applied to each side, and two layers are applied to each side. After spraying, the honeycomb is placed in an oven for heat treatment. The temperature is increased at a rate of (1~3)℃ / min to (375±5)℃, and held for 150min. Then, the temperature is lowered with the oven to obtain a reinforced high-temperature resistant microwave absorbing honeycomb. S6. Cut the absorbing honeycomb according to the component's external dimensions. The cutting size of the absorbing honeycomb should be the target size minus the skin size and then minus the estimated deformation. The skin thickness is 1mm, the deformation is 1mm, and the cutting allowance is 2mm. S7. Adjust the viscosity of the polyimide resin to 125±5CPS, use an impregnation device to impregnate the polyimide resin onto the surface of the glass fiber cloth, heat at 80℃ for 1 hour, and dry the solvent to obtain polyimide glass fiber prepreg. S8. Cut the polyimide fiberglass cloth prepreg according to the size requirements. Use the cut microwave absorbing honeycomb as the anode membrane. Lay the prepreg onto the surface of the microwave absorbing honeycomb with a thickness of 1mm. Place it in an autoclave for heating and pressurization according to the resin curing conditions. Increase the temperature at a rate of (1~3)℃ / min. After reaching (350±5)℃, start pressurizing to (1.5±0.02)MPa. During the pressurization process, continue to increase the temperature at a rate of (1~3)℃ / min to (375±5)℃ and hold for 150min. After the heat preservation is completed, start depressurizing. When the temperature drops to 60℃, release the vacuum. After demolding, the high-temperature resistant microwave absorbing honeycomb machine strip is obtained.

[0039] The completed component as shown in Example 2 Figure 2 As shown, the component was loaded onto the carrier for RCS testing, and the test results are as follows. Figure 5 and Figure 6 As shown, at 3 GHz, the average RCS in the metallic state is -14.415 dBsm, in the room-temperature absorbing state it is -17.300 dBsm, and after baking at 350°C it is -17.018 dBsm. The component's scattering characteristic control performance at room temperature and 350°C is similar, showing a significant improvement over the metallic state with the same shape. At 10 GHz, the average RCS in the metallic state is -13.767 dBsm, in the room-temperature absorbing state it is -14.981 dBsm, and after baking at 350°C it is -15.205 dBsm. The component's scattering characteristic control performance at room temperature and 350°C is similar, showing a significant improvement over the metallic state with the same shape.

[0040] In summary, the present invention provides a method for fabricating components based on 350℃ absorbing honeycomb, and the fabricated wing leading edge and fuselage strut components exhibit consistent performance at room temperature and high temperature, with a significant reduction in scattering characteristics compared to the metallic state.

[0041] Table 1. RCS Mean Statistics (dBsm) of Examples (3GHz) Table 2. RCS Mean Statistics (dBsm) of Examples (10GHz) Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a high-temperature resistant absorbing honeycomb component, characterized in that, include: S1, a preliminary sample of a microwave absorbing honeycomb was prepared using glass fiber cloth impregnated with polyimide resin; S2, mix carbon black, polyimide resin, solvent and additives to obtain microwave absorbing paste; S3, the microwave absorbing paste is sprayed onto the microwave absorbing honeycomb prototype and cured to obtain the microwave absorbing honeycomb; S4, using glass fiber cloth impregnated with polyimide resin to prepare skin prepreg; S5, using the absorbing honeycomb as a positive membrane, the skin prepreg is laid on its surface and cured to obtain a high-temperature resistant absorbing honeycomb component.

2. The method for preparing a high-temperature resistant absorbing honeycomb component according to claim 1, characterized in that, S1 includes: S101, glass fiber cloth is impregnated in polyimide resin to obtain a microwave absorbing honeycomb substrate; S102, the microwave absorbing honeycomb substrate is coated with polyimide node adhesive at intervals, stacked at preset intervals, and placed in a flatbed hot press for curing to obtain a preliminary microwave absorbing honeycomb sample.

3. The method for preparing a high-temperature resistant absorbing honeycomb component according to claim 2, characterized in that, In S101, the viscosity of the polyimide resin is adjusted to 125±5 CPS by mixing it with ethanol. After impregnation, the temperature is raised in an oven at a rate of 1~3℃ / min to 375±5℃, held for 150min, and then cooled down in the oven to obtain the microwave absorbing honeycomb substrate.

4. The method for preparing a high-temperature resistant absorbing honeycomb component according to claim 2, characterized in that, In S102, the viscosity of the joint adhesive is adjusted to 225±5 CPS; The curing process using a flatbed hot press includes: At room temperature, the pressure is 8~12 MPa; After pre-pressurization, the temperature is increased in the hot press at a rate of 1~3℃ / min. After reaching 350±5℃, the pressure is increased to 0.6±0.05MPa. During the pressurization process, the temperature is increased at a rate of 1~3℃ / min to 375±5℃. The temperature is held for 150min. The pressure is released and the product is removed when the temperature drops below 60℃.

5. A method for preparing a high-temperature resistant absorbing honeycomb component according to any one of claims 1-4, characterized in that, After obtaining the initial sample of the absorbing cell, the process also includes: The process of stretching the high-temperature resistant microwave absorbing honeycomb prototype involves simultaneously stretching and shaping the prototype to ensure that the cells can be evenly expanded. After stretching, immerse it in a polyimide solution with a viscosity of 125±5 CPS. After no excess liquid remains, let it stand for 15~20 minutes. Repeat the immersion and standing process several times. After impregnation, place the product in an oven for heat treatment, heating at a rate of 1~3℃ / min until it reaches 375±5℃, hold for 150min, and then cool down with the oven.

6. The method for preparing a high-temperature resistant absorbing honeycomb component according to claim 1, characterized in that, In S2, the ratio of carbon black, polyimide resin, solvent and additives is (8~12):(50~60):(10:20):(8~10).

7. The method for preparing a high-temperature resistant absorbing honeycomb component according to claim 1, characterized in that, In S3, after the coating is completed, it is placed in an oven for heat treatment. The temperature is increased at a rate of 1~3℃ / min to 375±5℃, held for 150min, and then cooled down with the oven.

8. The method for preparing a high-temperature resistant absorbing honeycomb component according to claim 1, characterized in that, Step S4 includes: The viscosity of the polyimide resin was adjusted to 125±5 CPS. The polyimide resin was impregnated onto the surface of the glass fiber cloth using an impregnation device. The mixture was heated at 80~100℃ for 1 hour and the solvent was dried to obtain the polyimide glass fiber prepreg.

9. The method for preparing a high-temperature resistant absorbing honeycomb component according to claim 1, characterized in that, S5 pressure curing includes: The temperature was increased at a rate of 1~3℃ / min, and after reaching 350±5℃, the pressure was increased to 1.5±0.02MPa. During the pressurization process, the temperature continues to rise to 375±5℃ at a rate of 1~3℃ / min, and is held at that temperature for 150min; After the heat preservation is completed, the pressure is reduced and the temperature drops to 60℃. The vacuum is then released, and the high-temperature resistant microwave absorbing honeycomb component is obtained after demolding.

10. A high-temperature resistant absorbing honeycomb component, characterized in that, Prepared according to any one of the preparation methods in claims 1-9.

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