A wave-absorbing honeycomb core and a preparation method thereof

Abstract

This application relates to the field of composite material technology, and in particular to a microwave absorbing honeycomb core and its preparation method; the preparation method of the microwave absorbing honeycomb core includes the following steps: preparing a polyether foam; placing the polyether foam into a foaming mold for in-situ foaming to obtain a first honeycomb core; wherein, the foaming mold consists of a groove and a honeycomb core, the honeycomb core is placed inside the groove, and the groove is used to fix the microwave absorbing honeycomb core; after the first honeycomb core is removed from the groove, it is vacuum cured, and then subjected to microwave absorbing impregnation treatment and drying treatment in sequence to obtain a second honeycomb core.

Description

Technical Field

[0001] This application relates to the field of composite material technology, and in particular to a microwave absorbing honeycomb core and its preparation method. Background Technology

[0002] Honeycomb sandwich structures are commonly used structural wave-absorbing structures, and they have the following advantages: due to the function of the core, they can comprehensively meet the requirements of lightweight, strong and rigid structural components; from the perspective of wave absorption performance, electromagnetic waves entering the structure from the surface wave-transparent layer can be scattered and absorbed multiple times through the core structure. Therefore, sandwich structures are more likely to achieve the "transmission, absorption and dispersion" effect of electromagnetic waves in the structure.

[0003] However, the microwave absorbing agent in the microwave absorbing honeycomb core prepared by the existing method is not evenly distributed, which leads to the microwave absorbing honeycomb core failing to meet application requirements. Summary of the Invention

[0004] The main objective of this application is to provide a microwave absorbing honeycomb core and its preparation method, aiming to solve the technical problem that the microwave absorbing honeycomb cores prepared by existing methods cannot meet application requirements.

[0005] To address the aforementioned technical problems, this application proposes a method for preparing a microwave absorbing honeycomb core, comprising the following steps:

[0006] Preparation of polyether foams;

[0007] The polyether foam is placed in a foaming mold for in-situ foaming to obtain a first honeycomb core; wherein, the foaming mold consists of a groove and a honeycomb core, the honeycomb core is placed inside the groove, and the groove is used to fix the microwave absorbing honeycomb core.

[0008] After the first honeycomb core is removed from the tank and vacuum cured, it is then subjected to microwave absorbing impregnation and drying treatments to obtain the second honeycomb core.

[0009] As some optional embodiments of this application, the groove in the foaming mold includes:

[0010] Base plate;

[0011] A glue tank, located above the base plate, is used to hold polyether foam.

[0012] The sidewalls are ≥4 in number and are connected to the base plate; each of the four sidewalls is provided with a groove for fixing the honeycomb core.

[0013] As some optional embodiments of this application, the step of removing the first honeycomb core from the tank, performing vacuum curing, and then sequentially performing microwave absorbing impregnation and drying treatments to obtain the second honeycomb core includes:

[0014] After the first honeycomb core is removed from the tank and vacuum cured, it is weighed to obtain the first weight value.

[0015] After the first honeycomb core is vacuum cured, it is then subjected to microwave absorbing impregnation and drying treatments in sequence to obtain the second honeycomb core.

[0016] The second honeycomb core is weighed to obtain a second weight value;

[0017] Based on the first weight value and the second weight value, the weight gain rate of the honeycomb core is obtained; based on the weight gain rate of the honeycomb core, it is determined whether the growth rate of the second honeycomb core meets the preset weight gain rate. If it does, the preparation is completed and the finished honeycomb core is obtained.

[0018] As some optional embodiments of this application, the step of obtaining the honeycomb core weight gain rate based on the first weight value and the second weight value; determining whether the second honeycomb core meets the preset weight gain rate based on the honeycomb core weight gain rate; if it does, the preparation is completed and a finished honeycomb core product is obtained, further comprising:

[0019] If the growth rate of the second honeycomb core does not meet the preset weight gain rate, the second honeycomb core will be subjected to microwave absorption impregnation and drying treatment again until the growth rate of the second honeycomb core meets the preset weight gain rate. The preparation is then completed and the finished honeycomb core is obtained.

[0020] As some optional embodiments of this application, the weight gain rate of the honeycomb core satisfies the following relationship:

[0021]

[0022] Wherein, ΔW represents the weight gain rate of the honeycomb core, W2 represents the weight value of the second honeycomb core, and W1 represents the weight value of the second honeycomb core; the preset weight gain rate is set to 0.1% to 2%.

[0023] As some optional embodiments of this application, the preparation of the polyether foam includes:

[0024] After mixing polyurethane prepolymer and polyether composition at a mass ratio of 1:1 to 2, the mixture is stirred evenly to obtain polyether foam; wherein the polyether composition includes at least one of foaming agent, pore-forming agent, catalyst and pore-opening agent.

[0025] As some optional embodiments of this application, the step of placing the polyether foam into a foaming mold for in-situ foaming to obtain a first honeycomb core includes:

[0026] Based on the honeycomb core, the theoretical weight value of the polyether foam is obtained;

[0027] Weigh the polyether foam based on its theoretical weight value, place it in a foaming mold, and let it stand at room temperature for 10 to 30 minutes to obtain the first honeycomb core.

[0028] As some optional embodiments of this application, the theoretical weight value of the polyether foam satisfies the following relationship:

[0029]

[0030] Wherein, W represents the theoretical weight of the polyether foam, L represents the length of the honeycomb core, W represents the width of the honeycomb core, H represents the thickness of the honeycomb core, T represents the cell size of the honeycomb core, R represents the target foam density after foaming, and A represents a coefficient with a value of 1 to 1.5.

[0031] As some optional embodiments of this application, the processing parameters of the vacuum curing treatment include: vacuum degree of -0.025±0.01Mpa, curing temperature of 65±5℃, and curing time of 60±10min.

[0032] As some optional embodiments of this application, the parameters of the microwave absorbing impregnation treatment include: impregnation time of 30±5 min and impregnation vacuum degree of -0.065±0.01 MPa;

[0033] The microwave absorbing agent used in the impregnation treatment is composed of conductive polymer materials, PVA and water.

[0034] As some optional embodiments of this application, the microwave absorbing agent is prepared by the following steps:

[0035] PVA and water are mixed at a volume ratio of 1:15 to 25, stirred evenly, heated to 90℃ to 95℃, kept at that temperature for 5 to 10 minutes, and then conductive polymer material is added and stirred to obtain a uniformly dispersed microwave absorbing agent solution.

[0036] As some optional embodiments of this application, the conductive polymer material includes at least one of nano-carbon materials and polyaniline.

[0037] As some optional embodiments of this application, the mass fraction of conductive polymer material in the microwave absorbing agent is 2% to 12%.

[0038] As some optional embodiments of this application, the parameters of the drying process include: drying temperature of 85±5℃ and drying time of 120±10min.

[0039] To address the aforementioned technical problems, this application also proposes: an absorbing honeycomb core, prepared by the above-described preparation method.

[0040] Currently, when using existing filling methods to prepare microwave absorbing honeycomb cores, the inability to fix the core results in uneven distribution of the absorbing agent within the core after foaming, making subsequent machining and bonding difficult. The method described in this application, however, involves placing the polyether foam into a foaming mold for in-situ foaming to obtain a first honeycomb core. The foaming mold consists of a groove and the honeycomb core, with the core placed inside the groove to fix it. After removing the first honeycomb core from the groove, it undergoes vacuum curing, followed by microwave absorbing impregnation and drying to obtain a second honeycomb core. By fixing the absorbing honeycomb core inside the groove, the cavity structure of the honeycomb core is fully utilized. Combined with a foaming mold of matching size, the foaming process is simple and controllable, resulting in uniform foam density. This facilitates the absorption of the absorbing agent into the pores of the foam during subsequent microwave absorbing impregnation, forming a conductive network and improving the conductivity of the absorbing honeycomb core, thus meeting application requirements. Attached Figure Description

[0041] Figure 1 This is a flowchart of the preparation method of the microwave absorbing honeycomb core described in the embodiments of this application;

[0042] Figure 2 This is a schematic diagram of the structure of the foaming mold described in the embodiments of this application;

[0043] Figure 3 This is a schematic diagram of the structure of the vacuum impregnation container described in the embodiments of this application;

[0044] In this diagram, 1 represents the base plate, 2 represents the glue tank, 3 represents the side wall, 4 represents the honeycomb core, 5 represents the groove, 6 represents the main container, 7 represents the sealing cap, 8 represents the rubber sleeve, 9 represents the vacuum pipeline interface, 10 represents the vacuum meter, and 11 represents the rubber pad. Detailed Implementation

[0045] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0046] Honeycomb sandwich structures are commonly used structural wave-absorbing structures, and they have the following advantages: due to the function of the core, they can comprehensively meet the requirements of lightweight, strong and rigid structural components; from the perspective of wave absorption performance, electromagnetic waves entering the structure from the surface wave-transparent layer can be scattered and absorbed multiple times through the core structure. Therefore, sandwich structures are more likely to achieve the "transmission, absorption and dispersion" effect of electromagnetic waves in the structure.

[0047] However, the microwave absorbing agent in the microwave absorbing honeycomb core prepared by the existing method is not evenly distributed, which leads to the microwave absorbing honeycomb core failing to meet application requirements.

[0048] Specifically, the traditional method for fabricating absorbing honeycomb structures involves impregnating a special absorbing slurry, formulated with absorbing agents and adhesives, onto an aramid paper honeycomb core. This method is mature, stable, highly repeatable, and low-cost, and has been widely used in stealth structures for aircraft. However, the preparation of the absorbing slurry and the impregnation process of the honeycomb core are cumbersome, requiring multiple impregnations and drying processes, and necessitating the use of large amounts of resin and organic solvents. This is unfriendly to operators and the environment, and also results in significant weight gain for the honeycomb core. The filling method for fabricating absorbing honeycomb cores has a long history, and the filling method has evolved from manual filling to automated mechanical filling. This method offers greater selectivity and adaptability to filling materials, a larger design space for performance, and promising application prospects. However, the filling method significantly reduces the processability of the honeycomb core structure, which has hindered its widespread engineering application. One study first prepared microwave absorbing foam by combining microwave absorbing agent with foam, and then filled the microwave absorbing foam into the core of the honeycomb core to prepare microwave absorbing honeycomb core. The test results showed that the microwave absorbing honeycomb core prepared by this method has better performance. However, this method also does not avoid the disadvantages of the filling method, and the addition of microwave absorbing agent will also increase the technical difficulty of foaming foam material.

[0049] Based on the aforementioned technical problems, such as Figure 1 As shown in the embodiments of this application, a method for preparing a microwave absorbing honeycomb core is proposed, comprising the following steps:

[0050] Step S10: Prepare polyether foam.

[0051] In a specific application, step S10, preparing the polyether foam, includes: mixing a polyurethane prepolymer and a polyether composition at a mass ratio of 1:1 to 2, and then stirring until homogeneous to obtain the polyether foam; wherein the polyether composition includes at least one of a foaming agent, a pore-forming agent, a catalyst, and a pore-opening agent. In a specific application, the stirring can be performed using a mechanical stirring device until the foaming liquid is homogeneous to obtain the polyether foam.

[0052] Step S20: Place the polyether foam into a foaming mold for in-situ foaming to obtain a first honeycomb core; wherein, the foaming mold consists of a groove and a honeycomb core, the honeycomb core is placed inside the groove, and the groove is used to fix the microwave absorbing honeycomb core.

[0053] In a specific application, step S20, which involves placing the polyether foam into a foaming mold for in-situ foaming to obtain a first honeycomb core, includes:

[0054] Step S21: Based on the honeycomb core, obtain the theoretical weight value of the polyether foam;

[0055] The theoretical weight of the polyether foam satisfies the following relationship:

[0056]

[0057] Wherein, W represents the theoretical weight of the polyether foam, L represents the length of the honeycomb core, W represents the width of the honeycomb core, H represents the thickness of the honeycomb core, T represents the cell size of the honeycomb core, R represents the target foam density after foaming, and A represents a coefficient with a value of 1 to 1.5.

[0058] Step S22: Weigh the polyether foam based on its theoretical weight value, place it in a foaming mold, and let it stand at room temperature for 10 to 30 minutes to obtain the first honeycomb core.

[0059] In specific applications, such as Figure 2 As shown, the tank in the foaming mold includes: a base plate 1; a glue tank 2, which is located above the base plate 1 and is used to hold polyether foam; and side walls 3, the number of which is ≥4, which are connected to the base plate 1. Each of the four side walls 3 has a groove 5 for fixing the honeycomb core 4. The side walls in the foaming mold can be connected to the base via pins to form a fixed but not sealed foaming space. That is, by fixing the microwave-absorbing honeycomb core inside the tank, the cavity structure of the honeycomb core is fully utilized. Combined with a foaming mold whose size matches the honeycomb core, the foaming process is simple and controllable, resulting in a uniform foam density. This facilitates the absorption agent's penetration of the foam pores during subsequent microwave-absorbing impregnation treatment, forming a conductive network and improving the conductivity of the microwave-absorbing honeycomb core, thus meeting application requirements.

[0060] Step S30: After the first honeycomb core is removed from the tank and vacuum cured, it is then subjected to microwave absorbing impregnation and drying treatments in sequence to obtain the second honeycomb core.

[0061] In specific applications, step S30, which involves removing the first honeycomb core from the tank and then vacuum curing it, followed by sequentially performing microwave absorbing impregnation and drying treatments to obtain the second honeycomb core, includes:

[0062] Step S31: After removing the first honeycomb core from the tank and performing vacuum curing, weigh it to obtain the first weight value;

[0063] Step S32: After vacuum curing the first honeycomb core, it is sequentially subjected to microwave absorbing impregnation and drying to obtain the second honeycomb core;

[0064] Step S33: Weigh the second honeycomb core to obtain a second weight value;

[0065] Step S34: Based on the first weight value and the second weight value, obtain the cell core weight gain rate; based on the cell core weight gain rate, determine whether the cell core growth rate of the second cell core meets the preset weight gain rate. If it does, the preparation is completed and the finished cell core is obtained; in some embodiments, if the cell core growth rate of the second cell core does not meet the preset weight gain rate, the second cell core is subjected to microwave absorbing impregnation treatment and drying treatment again until the cell core growth rate of the second cell core meets the preset weight gain rate, the preparation is completed and the finished cell core is obtained.

[0066] In practical applications, to effectively control the weight gain rate of the honeycomb core before and after impregnation, avoid significant weight gain due to excessive addition of microwave absorbing agent, which would affect its application, and reduce the manufacturing cost of the microwave absorbing honeycomb core, the weight gain rate of the honeycomb core satisfies the following relationship:

[0067]

[0068] Wherein, ΔW represents the weight gain rate of the honeycomb core, W2 represents the weight value of the second honeycomb core, and W1 represents the weight value of the second honeycomb core; the preset weight gain rate is set to 0.1% to 2%.

[0069] In specific applications, the processing parameters for the vacuum curing treatment include: a vacuum degree of -0.025±0.01 MPa, a curing temperature of 65±5℃, and a curing time of 60±10 min. The foamed honeycomb core is removed, the foam outside the core is cleaned, and the core is placed on a flat plate and sealed in a vacuum bag. A vacuum is then created to a vacuum degree of -0.025±0.01 MPa before curing. The curing temperature is 65±5℃, and the curing time is 60±10 min.

[0070] In specific applications, the parameters for the microwave absorbing impregnation treatment include: impregnation time of 30±5 min, and impregnation vacuum degree of -0.065±0.01 MPa; the microwave absorbing agent used in the impregnation treatment is composed of conductive polymer material, PVA, and water. Specifically, during the microwave absorbing impregnation treatment, the honeycomb core can be first immersed in a vacuum impregnation container containing the microwave absorbing agent, such as... Figure 3 As shown, the container consists of a main container 6 and a sealing cap 7. The main container 6 can be made of glass and has a rubber sleeve 8 on the upper edge. The sealing cap 7 includes a vacuum pipeline interface 9 and a vacuum gauge 10. There is a rubber gasket 11 on the mating surface with the main container 6. After mating, the main container 6 and the sealing cap 7 can be sealed by vacuuming. The vacuum degree is controlled at -0.065±0.01Mpa and the immersion time is 30±5min.

[0071] In specific applications, the microwave absorbing agent is prepared through the following steps: PVA and water are mixed at a volume ratio of 1:15 to 25, stirred until homogeneous, heated to 90°C to 95°C, and held at that temperature for 5 to 10 minutes. A conductive polymer material is then added and stirred to obtain a uniformly dispersed microwave absorbing agent solution. In some embodiments, the conductive polymer material includes at least one of nano-carbon materials and polyaniline. In some embodiments, the mass fraction of the conductive polymer material in the microwave absorbing agent is 2% to 12%. More specifically, mechanical stirring can be used during the stirring process, such as mechanical stirring for more than 10 minutes, to form a uniformly dispersed microwave absorbing solution.

[0072] In specific applications, the drying parameters include: drying temperature of 85±5℃ and drying time of 120±10min.

[0073] After the impregnation and curing processes are completed, the excess material of the honeycomb core can be removed by manual cutting or CNC machining to achieve the desired shape of the component, thus obtaining the final microwave absorbing honeycomb core product.

[0074] Currently, when using existing filling methods to prepare microwave absorbing honeycomb cores, the inability to fix the core results in uneven distribution of the absorbing agent within the core after foaming, making subsequent machining and bonding difficult. The method described in this application, however, involves placing the polyether foam into a foaming mold for in-situ foaming to obtain a first honeycomb core. The foaming mold consists of a groove and the honeycomb core, with the core placed inside the groove to fix it. After removing the first honeycomb core from the groove, it undergoes vacuum curing, followed by microwave absorbing impregnation and drying to obtain a second honeycomb core. By fixing the absorbing honeycomb core inside the groove, the cavity structure of the honeycomb core is fully utilized. Combined with a foaming mold of matching size, the foaming process is simple and controllable, resulting in uniform foam density. This facilitates the absorption of the absorbing agent into the pores of the foam during subsequent microwave absorbing impregnation, forming a conductive network and improving the conductivity of the absorbing honeycomb core, thus meeting application requirements.

[0075] In other words, the preparation method described in this application, which involves first in-situ foaming open-cell polyurethane foam inside the honeycomb core and then impregnating it with an electrical loss absorbing solution, avoids the problems of cumbersome processes, environmental unfriendliness, and weight gain associated with traditional impregnation processes for preparing absorbing honeycomb cores. It also avoids the problems of inconsistent absorbing agent distribution within the honeycomb core, which can affect subsequent machining and bonding, as seen in direct filling methods. Furthermore, the foaming and impregnation processes are carried out simultaneously, resulting in a low-difficulty and simple process suitable for large-scale engineering manufacturing. Simultaneously, this method for manufacturing absorbing honeycomb cores fully utilizes the cavity structure of the honeycomb core, expanding the design space and facilitating customization and high-performance design. Additionally, the use of a dedicated foaming mold makes the foaming process simple and controllable, with low energy consumption and high repeatability. The vacuum impregnation method after foaming facilitates the absorbing solution wetting the pores of the foamed foam, forming a conductive network, reducing the amount of absorbing agent required, and lowering the manufacturing cost of the absorbing honeycomb core.

[0076] Based on the above preparation method, this application also proposes a microwave absorbing honeycomb core prepared by the above preparation method.

[0077] Compared to absorbing honeycomb cores prepared by traditional methods, the absorbing honeycomb cores prepared by the above method have lightweight properties while maintaining broadband absorption performance, because the weight gain rate of the honeycomb core before and after impregnation is controlled by a special formula.

[0078] The absorbing honeycomb and its preparation method described in this application will be described in detail below with reference to specific embodiments:

[0079] Example 1

[0080] A method for preparing a microwave absorbing honeycomb core includes the following steps:

[0081] A polyurethane prepolymer and a polyether composition are mixed at a mass ratio of 1:1 to 2 and stirred until homogeneous to obtain a polyether foam; wherein the polyether composition includes at least one of a foaming agent, a pore-forming agent, a catalyst, and a pore-opening agent.

[0082] Based on the honeycomb core, the theoretical weight value of the polyether foam is obtained; based on the theoretical weight value of the polyether foam, the polyether foam is weighed and placed in a foaming mold, and allowed to stand and foam at room temperature for 10 min to 30 min to obtain the first honeycomb core; wherein, the foaming mold consists of a groove and a honeycomb core, the honeycomb core is placed inside the groove, and the groove is used to fix the absorbing honeycomb core.

[0083] The first honeycomb core was removed from the tank and vacuum-cured under conditions of -0.025±0.01 MPa, curing temperature of 65±5℃, and curing time of 60±10 min. It was then weighed to obtain a first weight value. After vacuum curing, the first honeycomb core was subjected to microwave absorbing impregnation under a vacuum of -0.065±0.01 MPa for 30±5 min, followed by drying at a drying temperature of 85±5℃ for 120±10 min to obtain the second honeycomb core. The second honeycomb core is weighed to obtain a second weight value. Based on the first and second weight values, the honeycomb core weight gain rate is obtained. Based on the honeycomb core weight gain rate, it is determined whether the honeycomb core growth rate of the second honeycomb core meets the preset weight gain rate. If it does, the preparation is complete, and the finished honeycomb core is obtained. If the honeycomb core growth rate of the second honeycomb core does not meet the preset weight gain rate, the second honeycomb core is subjected to microwave absorbing impregnation treatment and drying treatment again until the honeycomb core growth rate of the second honeycomb core meets the preset weight gain rate. The preparation is then complete, and the finished honeycomb core is obtained.

[0084] It should be noted that the weight gain rate of the honeycomb core satisfies the following relationship:

[0085]

[0086] Wherein, ΔW represents the weight gain rate of the honeycomb core, W2 represents the weight value of the second honeycomb core, and W1 represents the weight value of the second honeycomb core; the preset weight gain rate is set to 0.1% to 2%.

[0087] The theoretical weight of the polyether foam satisfies the following relationship:

[0088]

[0089] Wherein, W represents the theoretical weight of the polyether foam, L represents the length of the honeycomb core, W represents the width of the honeycomb core, H represents the thickness of the honeycomb core, T represents the cell size of the honeycomb core, R represents the target foam density after foaming, and A represents a coefficient with a value of 1 to 1.5.

[0090] The microwave absorber is prepared by the following steps:

[0091] PVA and water are mixed at a volume ratio of 1:15–25, stirred until homogeneous, heated to 90℃–95℃, and held at that temperature for 5–10 minutes. A conductive polymer material is then added and stirred to obtain a uniformly dispersed microwave absorbing agent solution. The conductive polymer material includes at least one of nano-carbon materials and polyaniline. The mass fraction of the conductive polymer material in the microwave absorbing agent is 2%–12%.

[0092] Compared with the absorbing honeycomb cores prepared by traditional methods, the absorbing honeycomb cores prepared by the method described in the above embodiments have lightweight properties while maintaining broadband absorption performance, because the weight gain rate of the honeycomb core before and after impregnation is controlled by a special formula.

[0093] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for preparing a microwave absorbing honeycomb core, characterized in that, Includes the following steps: Preparation of polyether foams; Based on the honeycomb core, the theoretical weight value of the polyether foam is obtained; based on the theoretical weight value of the polyether foam, the polyether foam is weighed, placed in a foaming mold, and allowed to foam at room temperature for 10-30 minutes to obtain the first honeycomb core; the theoretical weight value of the polyether foam satisfies the following relationship: Wherein, M represents the theoretical weight of the polyether foam, L represents the length of the honeycomb core, W represents the width of the honeycomb core, H represents the thickness of the honeycomb core, T represents the cell size of the honeycomb core, R represents the target foam density after foaming, and A represents a coefficient with a value of 1 to 1.5; wherein, the foaming mold consists of a groove and a honeycomb core, the honeycomb core is placed inside the groove, and the groove is used to fix the microwave absorbing honeycomb core; After the first honeycomb core is removed from the tank and vacuum cured, it is then subjected to microwave absorbing impregnation and drying treatments to obtain the second honeycomb core.

2. The method for preparing the absorbing honeycomb core according to claim 1, characterized in that, The groove in the foaming mold includes: Base plate; A glue tank, located above the base plate, is used to hold polyether foam. The sidewalls are ≥4 in number and are connected to the base plate; each of the four sidewalls is provided with a groove for fixing the honeycomb core.

3. The method for preparing the absorbing honeycomb core according to claim 1, characterized in that, The process of removing the first honeycomb core from the tank, vacuum curing it, and then sequentially performing microwave absorbing impregnation and drying treatments to obtain the second honeycomb core includes: After the first honeycomb core is removed from the tank and vacuum cured, it is weighed to obtain the first weight value. After the first honeycomb core is vacuum cured, it is then subjected to microwave absorbing impregnation and drying treatments in sequence to obtain the second honeycomb core. The second honeycomb core is weighed to obtain a second weight value; Based on the first weight value and the second weight value, the weight gain rate of the honeycomb core is obtained; based on the weight gain rate of the honeycomb core, it is determined whether the growth rate of the second honeycomb core meets the preset weight gain rate. If it does, the preparation is completed and the finished honeycomb core is obtained.

4. The method for preparing the absorbing honeycomb core according to claim 3, characterized in that, The cell core weight gain rate is obtained based on the first weight value and the second weight value; Based on the weight gain rate of the honeycomb core, it is determined whether the second honeycomb core meets the preset weight gain rate. If it does, the preparation is completed, and a finished honeycomb core is obtained. The process also includes: If the growth rate of the second honeycomb core does not meet the preset weight gain rate, the second honeycomb core will be subjected to microwave absorption impregnation and drying treatment again until the growth rate of the second honeycomb core meets the preset weight gain rate. The preparation is then completed and the finished honeycomb core is obtained.

5. The method for preparing the absorbing honeycomb core according to claim 3, characterized in that, The weight gain rate of the honeycomb core satisfies the following relationship: Wherein, ΔW represents the weight gain rate of the honeycomb core, W2 represents the weight value of the second honeycomb core, and W1 represents the weight value of the first honeycomb core.

6. The method for preparing the absorbing honeycomb core according to claim 1, characterized in that, The preparation of the polyether foam includes: After mixing polyurethane prepolymer and polyether composition at a mass ratio of 1:1 to 2, the mixture is stirred evenly to obtain polyether foam; wherein the polyether composition includes at least one of foaming agent, pore-forming agent, catalyst and pore-opening agent.

7. The method for preparing the absorbing honeycomb core according to claim 1, characterized in that, The processing parameters for the vacuum curing process include: vacuum degree of -0.025±0.01Mpa, curing temperature of 65±5℃, and curing time of 60±10min.

8. The method for preparing the absorbing honeycomb core according to claim 1, characterized in that, The parameters for the microwave absorbing impregnation treatment include: impregnation time of 30±5 min and impregnation vacuum degree of -0.065±0.01 MPa; The microwave absorbing agent used in the impregnation treatment is composed of conductive polymer materials, PVA and water.

9. The method for preparing the absorbing honeycomb core according to claim 8, characterized in that, The microwave absorber is prepared by the following steps: PVA and water are mixed at a volume ratio of 1:15~25, stirred evenly, heated to 90℃~95℃, kept at that temperature for 5min~10min, and then conductive polymer material is added and stirred to obtain a uniformly dispersed microwave absorbing agent solution.

10. The method for preparing the absorbing honeycomb core according to claim 9, characterized in that, The conductive polymer material includes at least one of nano-carbon materials and polyaniline.

11. The method for preparing the absorbing honeycomb core according to claim 9, characterized in that, The conductive polymer material in the microwave absorber has a mass fraction of 2% to 12%.

12. The method for preparing the absorbing honeycomb core according to claim 1, characterized in that, The parameters for the drying process include: drying temperature of 85±5℃ and drying time of 120±10min.

13. A microwave absorbing honeycomb core, characterized in that, It is prepared by the preparation method according to any one of claims 1-12.

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