Preparation method of wave-absorbing adhesive for repairing wave-absorbing honeycomb and repairing method of wave-absorbing honeycomb

Abstract

The invention discloses a preparation method of a wave-absorbing adhesive for repairing a wave-absorbing honeycomb and a repairing method of the wave-absorbing honeycomb. The method belongs to electromagnetic wave-absorbing structure damage repair. The wave-absorbing honeycomb is used for preparing the wave-absorbing adhesive, and the preparation convenience can be improved while the complexity of a wave-absorbing honeycomb damage repair material system is reduced. In addition, by means of the repairing method, the influence of a repairing interface on the wave absorbing performance can be effectively reduced, and the original wave absorbing performance of the wave absorbing honeycomb can be better recovered.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic wave-absorbing structure damage repair, and more particularly to a method for preparing a wave-absorbing adhesive for repairing a wave-absorbing honeycomb and a method for repairing the wave-absorbing honeycomb. Background Art

[0002] Absorbent honeycombs, made of aramid paper honeycombs impregnated with an absorbing coating, combine lightweight, high strength, and broadband absorption properties. They are widely used in applications such as stealth aircraft skins and radar shielding cabins. However, their honeycomb structure is susceptible to partial collapse or fracture when subjected to unexpected impacts, compromising their load-bearing and absorbing properties. Due to the high manufacturing cost of absorbing honeycombs, efficient and reliable repair technologies are crucial to extending their service life.

[0003] Unlike the repair of transparent aramid paper honeycombs, the key to the repair technology of absorbing honeycombs lies in the geometric shape of the damage removal and the matching of the electromagnetic parameters of the repair adhesive and the absorbing honeycomb. Chinese patent CN118829178A (publication date October 22, 2024) discloses a repair method based on the removal of cylindrical sections, which is achieved by wrapping the honeycomb replacement core with fiber cloth pre-impregnated with absorbing slurry and then embedding it into the damaged area to repair the performance of the absorbing honeycomb structure. However, the conductive slurry requires additional preparation of absorbing particles and resin adhesives, which increases the complexity of the repair material system. In addition, more absorbing slurry will remain in the absorbing honeycomb cells, resulting in a more significant impact of the repair interface on the absorbing performance. Summary of the Invention

[0004] In light of this, the present invention provides a method for preparing an absorbing adhesive for use in repairing absorbing honeycombs, and a method for repairing absorbing honeycombs. The methods aim to reduce the complexity of the repair adhesive material system, improve preparation convenience, reduce the impact of the repair interface on absorbing performance, and maximize the restoration of the original absorbing performance of the absorbing honeycomb.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing a microwave-absorbing adhesive for repairing microwave-absorbing honeycombs comprises the following steps:

[0007] S1: Preparation of grinding powder for microwave-absorbing honeycomb core

[0008] The wave-absorbing honeycomb core block with an outer contour volume of V is crushed and fully ground with a grinder to obtain the wave-absorbing honeycomb core grinding powder;

[0009] S2: Preparation of microwave-absorbing adhesive

[0010] Add appropriate amount of diluent to epoxy resin and stir thoroughly. After standing to eliminate bubbles, take epoxy resin with a volume of V into a cup, add absorbing honeycomb core grinding powder and dispersant in several times, stir thoroughly until there is no particle agglomeration, and then you can get the absorbing adhesive.

[0011] Preferably, the damaged honeycombs of the wave-absorbing honeycomb core block are of the same model.

[0012] Preferably, the particle size of the wave-absorbing honeycomb core grinding powder in step S1 is 80-120 meshes.

[0013] Preferably, the epoxy resin in step S2 includes any one of DG-8 epoxy resin, DG-2 epoxy resin, DG-3S epoxy resin, and DG-3S epoxy resin.

[0014] More preferably, the epoxy resin in step S2 is DG-8 epoxy resin.

[0015] Preferably, in step S2, the diluent is acetone or allyl glycidyl ether; and the dispersant is SP-7067 dispersant or D-346 dispersant.

[0016] Preferably, the diluent in step S2 accounts for 5% to 10% of the mass of the epoxy resin;

[0017] The dispersant accounts for 10% to 15% of the epoxy resin mass;

[0018] Another object of the present invention is to provide a method for repairing a microwave-absorbing honeycomb, comprising the following steps:

[0019] Step M1: Damage area removal and cleaning

[0020] Identify the damaged area of ​​the absorbing honeycomb and define the damage removal path. The minimum distance between the damage removal boundary and the visible damage area boundary is ≥ 2s, where s is the side length of the absorbing honeycomb cell. The damage removal area is a polygonal prism with its thickness along the absorbing honeycomb aperture direction. The lateral boundary of the damage removal area passes through the center of the absorbing honeycomb cell side wall. Remove the damaged area so that the width of the cell side wall after cutting the absorbing honeycomb is (0.5*s-0.3) mm. Then, clean the honeycomb core in the polished area with high-pressure airflow. Then, use a clean plain silk cloth dipped in acetone and wipe the polished area in one direction until the plain silk cloth is free of stains. After wiping with acetone, the repaired area should be left at room temperature for more than 20 minutes to allow the acetone in the repaired area to completely evaporate and ensure that there is no residual dust on the cavity side wall.

[0021] Step M2: Processing of microwave-absorbing honeycomb core

[0022] Select an absorbing honeycomb structure of the same model as the damaged honeycomb, and make a honeycomb replacement core according to the shape of the damage removal boundary. The height of the honeycomb replacement core is the same as the height of the damage removal area, and the side wall width of the absorbing honeycomb space cut at the edge of the honeycomb replacement core is (0.5*s-0.3) mm.

[0023] Step M3: Preparation of Absorbent Tape

[0024] The microwave-absorbing adhesive is prepared by the preparation method according to any one of claims 1 to 5, and is applied multiple times on a sponge strip or glass fiber cloth with a thickness of 0.4 mm, and pre-cured at room temperature for 10 to 15 minutes to prepare a microwave-absorbing tape;

[0025] Step M4: Repair the structural assembly

[0026] Lay a layer of J116A adhesive film on the bottom of the honeycomb structure cavity after the damage is removed; wrap the absorbing tape on the side wall of the absorbing honeycomb replacement core, and then slowly insert the tape-wrapped replacement core into the cavity, ensuring that the cells of the honeycomb replacement core are flush with the cells of the absorbing honeycomb after the damage is removed along the aperture direction, and that the side walls of the cells are aligned and in full contact with the absorbing tape;

[0027] Step M5: Glue curing

[0028] Apply 0.1-0.2MPa pressure along the honeycomb aperture direction and heat the repair area to 180℃±5℃ at a heating rate of (1.5~3.0)℃ / min and maintain the curing temperature for 2.5h~3.0h. Remove the applied pressure after heating is completed and the temperature drops to room temperature;

[0029] Step M6: Post-processing

[0030] Cut the excess absorbing tape in the cells along the direction of the honeycomb aperture to ensure that the absorbing honeycomb side wall coating is not damaged and the thickness of the remaining absorbing tape protruding from the cell side wall is ≤3mm.

[0031] Preferably, the polygonal prism in step M1 is a rhombus with a side length of d or an equilateral triangle cross section with a side length of d.

[0032] Preferably, the length of the absorbing tape in step M3 is 4d.

[0033] It can be seen from the above technical solutions that compared with the prior art, the present invention has the following beneficial effects:

[0034] The present invention utilizes absorbing honeycombs to prepare an absorbing adhesive, reducing the complexity of the absorbing honeycomb damage repair material system while improving its preparation convenience. Furthermore, the invented repair method effectively reduces the impact of the repair interface on absorbing performance, effectively restoring the original absorbing performance of the absorbing honeycomb. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0036] Figure 1 It is a wave-absorbing honeycomb damage structure.

[0037] Figure 2 Schematic diagram of damage removal path.

[0038] Figure 3 To remove damaged absorbing honeycomb structure.

[0039] Figure 4 This is the repaired wave-absorbing honeycomb structure.

[0040] Figure 5 This is a cross-sectional view of the repaired wave-absorbing honeycomb structure.

[0041] Figure 6 This is a comparison chart of the repair effect of Example 2 and the repair effect of the prior art.

[0042] Among them, in the figure:

[0043] 1-wave-absorbing honeycomb; 2-damaged honeycomb structure removed; 3-repaired wave-absorbing honeycomb structure; 31-replacement core; 32-wave-absorbing tape; 33-adhesive film. DETAILED DESCRIPTION

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0045] Example 1

[0046] This embodiment provides a method for preparing a microwave-absorbing adhesive for repairing microwave-absorbing honeycombs, comprising the following steps:

[0047] Step S1: Preparation of microwave-absorbing honeycomb core grinding powder. A microwave-absorbing honeycomb core block with an outer contour volume of V (the same model as the damaged honeycomb) is crushed and fully ground using a grinder to control the particle size to 80-120 mesh to obtain microwave-absorbing honeycomb core grinding powder;

[0048] Step S2: Preparation of an absorbing adhesive. Components A and B of DG-8 epoxy resin (purchased from the Xinjin Branch of Zhonglan Chenguang Chemical Research and Design Institute Co., Ltd.) are mixed in a ratio of 5:1. Acetone (7% of the DG-8 epoxy resin) is added and stirred thoroughly. After standing to eliminate bubbles, a volume V of epoxy resin is placed in a cup. Absorbent honeycomb core grinding powder and SP-7067 dispersant (13% of the epoxy resin mass) are added in multiple portions. Stir thoroughly until no particles agglomerate. This yields the absorbing adhesive.

[0049] Example 2

[0050] This embodiment provides a method for repairing a microwave-absorbing honeycomb, comprising the following steps:

[0051] Step M1: Damage area removal and cleaning.

[0052] Identify the damaged area of ​​the absorbing honeycomb 1 and define the damage removal path. The minimum distance between the damage removal boundary and the visible damage area boundary is at least greater than or equal to 2s, where s is the side length of the absorbing honeycomb 1 cell. The damage removal area is a polygonal prism with its thickness along the absorbing honeycomb aperture direction. The lateral boundary of the damage removal area must pass through the center of the side wall of the absorbing honeycomb 1 cell. Figure 2 The damaged area is removed by using electric or pneumatic grinding tools and carving knives. The width of the cell side wall after cutting the absorbing honeycomb 1 is (0.5s-0.3) mm. The absorbing honeycomb structure 3 after the damaged area is removed is as shown in FIG. Figure 3 Then, clean the honeycomb core of the polished area with high-pressure airflow. Then, use a clean plain silk cloth dipped in acetone to wipe the polished area in one direction until the plain silk cloth is free of stains. The repaired area cleaned with acetone should be left to air at room temperature for more than 20 minutes to allow the acetone in the repaired area to completely evaporate and ensure that there is no residual dust on the cavity sidewalls.

[0053] Step M2: Processing the microwave-absorbing honeycomb replacement core 31 .

[0054] Select an absorbing honeycomb structure of the same model as the damaged honeycomb and fabricate a honeycomb replacement core in the shape of the damaged removal boundary. The height of the honeycomb replacement core is the same as the height of the damaged removal area, and the sidewall width of the absorbing honeycomb cells cut at the edge of the honeycomb replacement core is also (0.5*s-0.3) mm.

[0055] Step M3: Preparation of absorbing tape.

[0056] Using intact honeycomb blocks, damaged absorbing honeycomb structures with portions removed, or honeycomb core replacement processing waste, an absorbing adhesive is prepared according to step S2. The adhesive is then applied multiple times to a 0.4 mm thick sponge strip or glass fiber cloth and pre-cured at room temperature for 13 minutes to prepare an absorbing tape 32. The absorbing tape 32 has a length of 4 d.

[0057] Step M4: Repair the structural assembly.

[0058] Lay a layer of J116A adhesive film 33 on the bottom of the cavity of the honeycomb structure 2 after the damage is removed. Wrap the absorbing tape 32 on the side wall of the absorbing honeycomb replacement core, and then slowly insert the replacement core 31 wrapped with the tape 32 into the cavity, ensuring that the cells of the honeycomb replacement core 31 are flush with the cells of the absorbing honeycomb 2 after the damage is removed along the aperture direction, and that the cell sidewalls in the sidewall direction are aligned and fully in contact with the absorbing tape. Avoid the absorbing glue from sticking to other spaces. Figure 4 and Figure 5 shown.

[0059] Step M5: Glue curing.

[0060] Apply 0.2 MPa of pressure along the honeycomb aperture and heat the repair area at a rate of (2.0)°C / min to 180°C ± 5°C. Maintain the curing temperature for 2.5 hours. Remove the pressure after heating is complete and the temperature has cooled to room temperature. Heating the repair area can be achieved using a thermocouple, electric blanket, or infrared lamp.

[0061] Step M6: Post-processing.

[0062] Use a tool such as a carving knife to cut away the excess absorbing tape in the honeycomb cells along the direction of the honeycomb aperture, ensuring that the absorbing honeycomb sidewall coating is not damaged. The thickness of the remaining absorbing tape protruding from the cell sidewall should be no more than 0.3mm.

[0063] The vertical reflectivity after repairing the wave-absorbing honeycomb structure using the present invention and the prior art (CN 115497584 A) is as follows: Figure 6 As shown, the comparison shows that the present invention has a better repair effect (the vertical reversal curve of the structure repaired by this technology is more consistent with the vertical reversal curve of the intact honeycomb).

[0064] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0065] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a microwave-absorbing adhesive for repairing microwave-absorbing honeycombs, characterized in that: The following steps are involved: S1: Preparation of grinding powder for microwave-absorbing honeycomb core The wave-absorbing honeycomb core block with an outer contour volume of V is crushed and fully ground with a grinder to obtain the wave-absorbing honeycomb core grinding powder; S2: Preparation of microwave-absorbing adhesive Add appropriate amount of diluent to epoxy resin and stir thoroughly. After standing to eliminate bubbles, take epoxy resin with a volume of V into a cup, add absorbing honeycomb core grinding powder and dispersant in several times, stir thoroughly until there is no particle agglomeration, and then you can get the absorbing adhesive.

2. The method for preparing a microwave-absorbing adhesive for repairing microwave-absorbing honeycombs according to claim 1, characterized in that: The damaged honeycombs in the wave-absorbing honeycomb core block are of the same model.

3. The method for preparing a microwave-absorbing adhesive for repairing microwave-absorbing honeycombs according to claim 1, wherein: The particle size of the wave-absorbing honeycomb core grinding powder in step S1 is 80-120 meshes.

4. The method for preparing a microwave-absorbing adhesive for repairing microwave-absorbing honeycombs according to claim 1, wherein: The epoxy resin in step S2 includes any one of DG-8 epoxy resin, DG-2 epoxy resin, DG-3S epoxy resin, and DG-3S epoxy resin.

5. The method for preparing a microwave-absorbing adhesive for repairing microwave-absorbing honeycombs according to claim 4, characterized in that: The epoxy resin in step S2 is DG-8 epoxy resin.

6. The method for preparing a microwave-absorbing adhesive for repairing microwave-absorbing honeycombs according to claim 1, characterized in that: In step S2, the diluent is acetone or allyl glycidyl ether; and the dispersant is SP-7067 dispersant or D-346 dispersant.

7. The method for preparing a microwave-absorbing adhesive for repairing microwave-absorbing honeycombs according to claim 6, wherein: The diluent in step S2 accounts for 5% to 10% of the mass of the epoxy resin; The dispersant accounts for 10% to 15% of the mass of the epoxy resin.

8. A method for repairing a microwave-absorbing honeycomb, characterized in that: The following steps are involved: Step M1: Damage area removal and cleaning Identify the damaged area of ​​the absorbing honeycomb. The minimum distance between the damage removal boundary and the visible damage area boundary is ≥ 2s, where s is the side length of the absorbing honeycomb cell. The damage removal area is a polygonal prism with its thickness along the absorbing honeycomb aperture direction. The lateral boundary of the damage removal area passes through the center of the absorbing honeycomb cell side wall. Remove the damaged area so that the width of the cell side wall after the absorbing honeycomb is cut is (0.5*s-0.3) mm. Step M2: Processing of microwave-absorbing honeycomb core Select an absorbing honeycomb structure of the same model as the damaged honeycomb, and make a honeycomb replacement core according to the shape of the damage removal boundary. The height of the honeycomb replacement core is the same as the height of the damage removal area, and the side wall width of the absorbing honeycomb space cut at the edge of the honeycomb replacement core is (0.5*s-0.3) mm. Step M3: Preparation of Absorbent Tape The microwave-absorbing adhesive is prepared by the preparation method according to any one of claims 1 to 6, and is applied multiple times on a sponge strip or glass fiber cloth having a thickness of 0.4 mm, and pre-cured at room temperature for 10 to 15 minutes to prepare a microwave-absorbing tape; Step M4: Repair the structural assembly Lay a layer of J116A adhesive film on the bottom of the honeycomb structure cavity after the damage is removed; wrap the absorbing tape on the side wall of the absorbing honeycomb replacement core, and then slowly insert the tape-wrapped replacement core into the cavity, ensuring that the cells of the honeycomb replacement core are flush with the cells of the absorbing honeycomb after the damage is removed along the aperture direction, and that the side walls of the cells are aligned and in full contact with the absorbing tape; Step M5: Glue curing Apply 0.1-0.2MPa pressure along the honeycomb aperture direction and heat the repair area to 180℃±5℃ at a heating rate of (1.5~3.0)℃ / min and maintain the curing temperature for 2.5h~3.0h. Remove the applied pressure after heating is completed and the temperature drops to room temperature; Step M6: Post-processing Cut the excess absorbing tape in the cells along the direction of the honeycomb aperture to ensure that the absorbing honeycomb side wall coating is not damaged and the thickness of the remaining absorbing tape protruding from the cell side wall is ≤3mm.

9. The method for repairing a microwave-absorbing honeycomb according to claim 8, characterized in that: The polygonal prism in step M1 is a rhombus with a side length of d or an equilateral triangle cross section with a side length of d.

10. The method for repairing a microwave-absorbing honeycomb according to claim 8, characterized in that: The length of the absorbing tape in step M3 is 4d.

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