Method of bonding an aluminum honeycomb structure

Abstract

This invention discloses a bonding method for aluminum honeycomb structural components, comprising the following steps: S1. Composite surface modification treatment: including anodizing, plasma etching, and coupling agent coating; S2. Preparation of nano-reinforced adhesive; S3. Pre-curing of adhesive film: uniformly coating the nano-reinforced adhesive onto the inner surface of the modified aluminum panel, followed by pre-curing; S4. Honeycomb core positioning and gradient pressure; S5. Selective coating and penetration; S6. Stepwise curing. This invention, through composite surface modification treatment and the addition of nano-reinforced adhesive, constructs a skeleton-filler composite adhesive layer structure. Utilizing the synergistic innovation of gradient pressure and stepwise curing processes, it achieves efficient and reliable bonding of aluminum honeycomb structural components, effectively solving problems such as weak interfacial bonding, poor environmental stability, and low peel strength in existing bonding technologies. The process is simple and suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of composite material bonding technology, and in particular to a bonding method for aluminum honeycomb structural components. Background Technology

[0002] Aluminum honeycomb structural components are widely used in aerospace, rail transportation, and building curtain walls due to their advantages such as high specific strength, high stiffness, and light weight. In these applications, aluminum honeycomb materials are typically connected using welding, riveting, or adhesive bonding techniques. However, traditional adhesive bonding methods are prone to insufficient connection strength, aging of the adhesive interface, and corrosion when exposed to environmental factors such as high temperature, humidity, and mechanical impact, thus affecting the reliability and service life of the aluminum honeycomb structural components. Adhesive bonding is a core technology in the manufacturing of aluminum honeycomb structural components, and its quality directly determines the mechanical properties and service reliability of the components.

[0003] Existing bonding methods mostly use conventional epoxy resin adhesives or polyurethane adhesives. Although these adhesives have high bonding strength after curing, they are prone to stress concentration and adhesive layer cracking during long-term use, especially when exposed to external temperature fluctuations and humidity. This leads to a decrease in the strength of the bonded parts and affects the stability of the overall structure.

[0004] Therefore, there is an urgent need for an adhesive bonding method for aluminum honeycomb structures that can simultaneously achieve high interfacial bonding strength, excellent environmental resistance, and high efficiency and controllability. Summary of the Invention

[0005] The purpose of this invention is to provide a bonding method for aluminum honeycomb structural components to solve the problems of insufficient bonding strength and poor weather resistance in the above-mentioned background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A bonding method for aluminum honeycomb structural components includes the following steps:

[0008] S1. Composite surface modification treatment: The bonding surfaces of the aluminum honeycomb core and the aluminum panel are sequentially subjected to anodizing, plasma etching, and coupling agent coating to obtain the modified aluminum honeycomb core and aluminum panel.

[0009] S2. Preparation of nano-reinforced adhesive: Epoxy resin E-51 and curing agent 4,4'-diaminodiphenyl sulfone are mixed at a mass ratio of 100:25~35 to obtain a mixture. Then, 2~5% of the mass of the mixture of nano-alumina particles and 0.5~1.5% of the mass of the mixture of dispersant are added. After treatment with ultrasonic equipment, the mixture is stirred at high speed to obtain nano-reinforced adhesive.

[0010] S3. Pre-curing of adhesive film: The nano-reinforced adhesive is uniformly coated on the inner surface of the modified aluminum panel, with a coating thickness of 0.1~0.3mm, and then pre-cured using a constant temperature hot press.

[0011] S4. Honeycomb core positioning and gradient pressure: The modified aluminum honeycomb core is precisely placed on the pre-cured bottom layer aluminum panel and assembled using gradient pressure.

[0012] S5. Selective Coating and Penetration: The nano-reinforced adhesive is selectively coated again on the nodes of the honeycomb core strip and the edge areas in contact with the aluminum panel, and penetrating is carried out by capillary action.

[0013] S6. Step-by-step curing: Place the assembled structural components in a curing oven and cure them at 80~90℃ for 60~90min. Then, raise the temperature to 120~130℃ and cure for 120~150min. Finally, cool the components to room temperature at a rate of 2~3℃ / min to complete the curing process.

[0014] As a preferred embodiment of the present invention, in step S1, the electrolyte in the anodic oxidation is a mixture of oxalic acid with a mass concentration of 3-5% and sulfuric acid with a mass concentration of 15-20%, wherein the volume ratio of oxalic acid with a mass concentration of 3-5% to sulfuric acid with a mass concentration of 15-20% is 1:3-5, the oxidation voltage is set to 12-18V, the temperature is 18-25℃, and the oxidation time is 15-25min.

[0015] As a preferred embodiment of the present invention, in step S1, plasma etching uses a mixed gas source of argon and oxygen, wherein the volume ratio of argon to oxygen is 4~6:1, the power is 300~500W, the vacuum degree is 0.05~0.1MPa, and the processing time is 3~8min.

[0016] As a preferred embodiment of the present invention, in step S1, the coupling agent is an ethanol solution of γ-aminopropyltriethoxysilane with a mass concentration of 1.5-3%, and after uniform coating with the coupling agent, it is dried at 80-100°C for 10-15 minutes.

[0017] In a preferred embodiment of the present invention, in step S2, the particle size of the nano-alumina particles is 50-100 nm; the dispersant is either triethanolamine or polyethylene glycol.

[0018] As a preferred embodiment of the present invention, in step S2, the ultrasonic power of the ultrasonic device is 100~300W, the ultrasonic frequency is 20~40kHz, and the ultrasonic time is 20~30min; the stirring rate is 2500~3500rpm, and the time is 15~20min.

[0019] As a preferred embodiment of the present invention, in step S3, the temperature of the constant temperature hot press is 80~100℃, the pressure is 0.1~0.3MPa, and the time is 20~40min.

[0020] As a preferred embodiment of the present invention, in step S4, the initial pressure during gradient pressurization is 0.3~0.5MPa, the pressure holding time is 5~10min, and then the pressure is increased to 1.2~1.5MPa at a rate of 0.2MPa / min, and the pressure is held for 10~15min before the process ends.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. This invention employs a three-stage processing method: anodizing, plasma etching, and coupling agent coating. This comprehensively optimizes the adhesive performance of aluminum-based materials from three dimensions: surface morphology, chemical properties, and interfacial bonding. Anodizing uses a mixture of oxalic acid and sulfuric acid as the electrolyte, generating a uniform and porous oxide film on the surface of the aluminum honeycomb core and aluminum panel. This not only increases surface roughness but also forms an active surface layer rich in hydroxyl groups, providing a physical anchoring basis for subsequent processing. Plasma etching uses a mixture of argon and oxygen as the gas source. The physical etching of argon further refines the surface texture of the oxide film and increases the specific surface area; oxygen introduces oxygen-containing functional groups such as carboxyl and hydroxyl groups, improving surface polarity and wettability, solving the problems of oil residue and oxide film inertness on the aluminum surface, and enhancing the spreadability of the adhesive. The γ-aminopropyltriethoxysilane layer formed by coupling agent coating binds to inorganic groups on the aluminum surface at one end via silicon-oxygen bonds, while the other end reacts with organic adhesives via amino groups, constructing an "inorganic-organic" transition interface. This eliminates interfacial compatibility differences. After subsequent drying and curing, the coupling layer further enhances resistance to humid heat aging and reduces the risk of interfacial failure. This three-step composite treatment endows the aluminum substrate surface with both physical anchoring structures and chemically active sites, significantly improving the adhesion strength and interfacial bonding stability of the nano-reinforced adhesive, laying a crucial foundation for subsequent bonding processes.

[0023] 2. This invention introduces nano-alumina particles into the epoxy resin system. Alumina with a particle size of 50-100 nm possesses both high specific surface area and high activity, enabling it to form a tight interfacial bond with the resin matrix. Through the "nano-reinforcement effect," the mechanical properties of the adhesive, such as shear strength and compressive strength, as well as its thermal stability, are significantly improved, solving the problem of insufficient bonding strength in traditional adhesives. Combined with ultrasonic dispersion and high-speed stirring, nanoparticle agglomeration is effectively avoided, ensuring uniform distribution within the adhesive, resulting in more stable bonding strength and reducing localized weak points. Furthermore, this adhesive exhibits excellent coatability and penetration capabilities, satisfying the need for uniform coating while also penetrating to honeycomb core nodes and edges via capillary action, strengthening adhesion in critical areas and providing core support for structural stability after subsequent step-by-step curing.

[0024] 3. In this invention, a stable "skeleton" layer is formed by pre-curing the bottom adhesive film, effectively avoiding the problem of the adhesive clogging the honeycomb grid due to excessive fluidity in the early stages of curing, as in traditional methods. Then, selective coating is used as a "filler" material specifically to reinforce key stress areas such as nodes and edges at the bonding interface. This achieves precise adhesive distribution, ensuring sufficient bonding area while minimizing structural weight, and significantly improving peel strength and fatigue resistance.

[0025] 4. This invention first applies low pressure to bond the honeycomb core and adhesive film, avoiding direct high pressure that could crush the brittle honeycomb structure and prevent deformation and collapse. Then, the pressure is gradually increased to push the adhesive to evenly fill the gaps in the honeycomb core nodes and edges, expelling interfacial air and reducing defects such as bubbles. This gradient pressure method better ensures the tightness of the adhesive surface. Furthermore, through step-by-step curing—first, low-temperature pre-curing to allow the adhesive to initially cross-link and solidify, preventing excessive flow of the adhesive at high temperatures that could lead to accumulation within the honeycomb cells or uneven adhesive layers; then, high temperature to achieve full cross-linking of the adhesive, improving bond strength and weather resistance; finally, slow cooling to balance the thermal stress difference between the aluminum panel and the honeycomb core, preventing cracking due to uneven shrinkage and ensuring the overall stability and service life of the structural components. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating the bonding process of the aluminum honeycomb structure component of the present invention. Detailed Implementation

[0027] 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 only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] This three-step process—anodizing, plasma etching, and coupling agent coating—comprehensively optimizes the adhesive properties of aluminum-based materials from multiple dimensions, including surface morphology, chemical properties, and interfacial bonding. First, anodizing uses a mixture of oxalic acid and sulfuric acid as the electrolyte to generate a uniform porous oxide film on the surfaces of the aluminum honeycomb core and aluminum panel. This not only increases surface roughness but also forms a hydroxyl-rich active layer, providing a physical anchoring foundation for subsequent processing. Plasma etching uses a mixture of argon and oxygen. The physical etching action of argon further refines the surface texture of the oxide film, increasing the specific surface area. Simultaneously, oxygen introduces oxygen-containing functional groups such as carboxyl and hydroxyl groups, enhancing surface polarity and wettability. This solves the problem of oil residue on the aluminum surface and the inertia of the oxide film, and also enhances the spreadability of the adhesive. The γ-aminopropyltriethoxysilane layer formed by coupling agent coating binds to inorganic groups on the aluminum surface through silicon-oxygen bonds and reacts with organic adhesives via amino groups, forming a transition interface between inorganic and organic components. This eliminates compatibility differences between interfaces. After drying and curing, the coupling layer also improves resistance to humid heat aging and reduces the risk of interface failure. This three-step composite treatment endows the aluminum substrate surface with both a physical anchoring structure and chemically active sites, significantly improving the adhesion strength and interfacial bonding stability of the nano-reinforced adhesive, laying a solid foundation for subsequent bonding processes.

[0029] By introducing nano-alumina particles into the epoxy resin system, these nano-sized particles not only possess a high specific surface area but also exhibit strong activity, enabling them to form a tight interfacial bond with the resin matrix. This alumina particle size range significantly enhances the adhesive's shear strength, compressive strength, and thermal stability through a "nano-reinforcing effect," effectively solving the problem of insufficient bond strength in traditional adhesives. To prevent nanoparticle agglomeration and ensure their uniform distribution within the adhesive, ultrasonic dispersion and high-speed stirring are employed. This not only maintains the stability of the bond strength but also reduces the formation of localized weak points. Furthermore, this adhesive exhibits excellent coatability and permeability, meeting the requirements for uniform coating and penetrating to honeycomb core nodes and edges through capillary action, thereby strengthening the bond effect in critical areas. Ultimately, this optimized design will provide crucial support for the structural stability after subsequent curing.

[0030] Pre-curing the underlying adhesive film creates a stable "skeleton" layer, effectively avoiding the problem of excessive adhesive flow clogging the honeycomb cells during the initial curing stage, a common issue in traditional processes. Subsequently, selective coating uses the adhesive as a "filler," specifically targeting key stress-bearing areas such as joints and edges at the bonding interface. This process achieves precise adhesive distribution, ensuring sufficient bonding area while minimizing structural weight and significantly improving peel strength and fatigue resistance.

[0031] By employing a gradient pressure method, the honeycomb core and adhesive film are first bonded under low pressure to avoid crushing and deformation of the brittle honeycomb structure caused by direct high pressure. Then, the pressure is gradually increased to push the adhesive to evenly fill the gaps between the honeycomb core nodes and edges, while simultaneously expelling interfacial air and reducing defects such as bubbles. This gradient pressure method effectively ensures the tightness of the adhesive surface. In addition, a step-by-step curing process is adopted. First, pre-curing is carried out at a low temperature to allow the adhesive to initially cross-link and set, thereby avoiding excessive flow of adhesive during subsequent high-temperature curing, which could lead to accumulation or uneven adhesive layers within the honeycomb cells. Then, high-temperature curing fully cross-links the adhesive, improving bond strength and weather resistance. Finally, slow cooling is used to balance the thermal stress difference between the aluminum panel and the honeycomb core, preventing cracks caused by uneven shrinkage, thus ensuring the overall stability and service life of the structural components.

[0032] Please see Figure 1 This application provides a bonding method for aluminum honeycomb structural components, comprising the following steps: S1. Composite surface modification treatment: The bonding surfaces of the aluminum honeycomb core and the aluminum panel are sequentially subjected to anodizing, plasma etching, and coupling agent coating treatment to obtain modified aluminum honeycomb core and aluminum panel. S2. Preparation of nano-reinforced adhesive: Epoxy resin E-51 and curing agent 4,4'-diaminodiphenyl sulfone are mixed at a mass ratio of 100:25~35 to obtain a mixture. Then, 2~5% of the mass of nano-alumina particles and 0.5~1.5% of the mass of dispersant are added to the mixture. After treatment with ultrasonic equipment, the mixture is stirred at high speed to obtain a nano-reinforced adhesive. S3. Pre-curing of adhesive film: The nano-reinforced adhesive is uniformly coated on the inner surface bonding surface of the modified aluminum panel with a coating thickness of 0.1~0.3mm, and then pre-cured using a constant temperature hot press. S4. Honeycomb Core Positioning and Gradient Pressing: The modified aluminum honeycomb core is precisely placed on the pre-cured bottom adhesive film aluminum panel, and assembly is performed using gradient pressing. S5. Selective Coating and Penetration: The nano-reinforced adhesive is selectively coated again on the nodes of the honeycomb core strips and the edges in contact with the aluminum panel, and penetration is achieved using capillary action. S6. Stepwise Curing: The assembled structural components are placed in a curing oven, first cured at 80~90℃ for 60~90 min, then the temperature is increased to 120~130℃ for 120~150 min, and finally cooled to room temperature at a rate of 2~3℃ / min to complete curing.

[0033] All raw materials used in this invention are commercially available.

[0034] Example 1

[0035] A bonding method for aluminum honeycomb structural components includes the following steps:

[0036] S1. Composite Surface Modification Treatment: The bonding surfaces of the aluminum honeycomb core and aluminum panel are subjected to anodizing treatment. The anodizing voltage is set to 18V, the temperature is 25℃, and the electrolyte is a mixture of 5% oxalic acid solution and 20% sulfuric acid solution at a volume ratio of 1:5. The anodizing time is 25min. After anodizing, plasma etching is performed using a mixed gas source of argon and oxygen at a volume ratio of 6:1, the power is set to 500W, the vacuum degree is 0.1MPa, and the processing time is 8min. Then, a coupling agent (an ethanol solution of 3% γ-aminopropyltriethoxysilane at a mass concentration) is uniformly coated and dried at 100℃ for 15min to obtain the modified aluminum honeycomb core and aluminum panel.

[0037] S2. Preparation of nano-reinforced adhesive: Epoxy resin E-51 and curing agent 4,4'-diaminodiphenyl sulfone were mixed at a mass ratio of 100:35 to obtain a mixture. Then, 5% of the mass of the mixture was added with nano-alumina particles (particle size of 100 nm) and 1.5% of the mass of the mixture with dispersant polyethylene glycol. The mixture was then treated with an ultrasonic device with an ultrasonic power of 300 W, an ultrasonic frequency of 40 kHz, and an ultrasonic time of 30 min. The mixture was then stirred at a high speed of 3500 rpm for 20 min to obtain the nano-reinforced adhesive.

[0038] S3. Pre-curing of adhesive film: The nano-reinforced adhesive is uniformly coated on the inner surface of the modified aluminum panel, with a coating thickness of 0.3mm. Then, a constant temperature hot press is used for pre-curing. The temperature of the constant temperature hot press is 100℃, the pressure is 0.3MPa, and the time is 40min.

[0039] S4. Cellular Core Positioning and Gradient Pressurization: The modified cellular core is precisely placed on the pre-cured bottom layer adhesive film aluminum panel and assembled using gradient pressurization. The initial pressure during gradient pressurization is 0.5 MPa, the holding time is 10 min, and then the pressure is increased to 1.5 MPa at a rate of 0.2 MPa / min and held for 15 min before the assembly is completed.

[0040] S5. Selective Coating and Penetration: The nano-reinforced adhesive is selectively coated again on the nodes of the honeycomb core strip and the edge areas in contact with the aluminum panel, and penetrating by capillary action;

[0041] S6. Step-by-step curing: Place the assembled structural components in a curing oven, first cure at 90℃ for 90 minutes, then raise the temperature to 130℃ for 150 minutes, and finally cool down to room temperature at a rate of 3℃ / min to complete the curing.

[0042] Example 2

[0043] A bonding method for aluminum honeycomb structural components includes the following steps:

[0044] S1. Composite Surface Modification Treatment: The bonding surfaces of the aluminum honeycomb core and aluminum panel are subjected to anodizing treatment. The anodizing voltage is set to 12V, the temperature is 18℃, and the electrolyte is a mixture of 3% oxalic acid solution and 15% sulfuric acid solution in a volume ratio of 1:3. The anodizing time is 15min. After anodizing, plasma etching is performed using a mixed gas source of argon and oxygen in a volume ratio of 4:1. The power is set to 300W, the vacuum degree is 0.05MPa, and the processing time is 3min. Then, a coupling agent (an ethanol solution of 1.5% γ-aminopropyltriethoxysilane in a mass concentration) is uniformly coated and dried at 80℃ for 10min to obtain the modified aluminum honeycomb core and aluminum panel.

[0045] S2. Preparation of nano-reinforced adhesive: Epoxy resin E-51 and curing agent 4,4'-diaminodiphenyl sulfone were mixed at a mass ratio of 100:25 to obtain a mixture. Then, 2% by mass of nano-alumina particles (particle size of 50nm) and 0.5% by mass of dispersant polyethylene glycol were added to the mixture. The mixture was then treated with an ultrasonic device with an ultrasonic power of 100W, an ultrasonic frequency of 20kHz, and an ultrasonic time of 20min. The mixture was then stirred at a high speed of 2500rpm for 15min to obtain the nano-reinforced adhesive.

[0046] S3. Pre-curing of adhesive film: The nano-reinforced adhesive is uniformly coated on the inner surface of the modified aluminum panel, with a coating thickness of 0.1 mm. Then, a constant temperature hot press is used for pre-curing. The temperature of the constant temperature hot press is 80℃, the pressure is 0.1 MPa, and the time is 20 min.

[0047] S4. Cellular Core Positioning and Gradient Pressurization: The modified cellular core is precisely placed on the pre-cured bottom layer adhesive film aluminum panel and assembled using gradient pressurization. The initial pressure during gradient pressurization is 0.3 MPa, the holding time is 5 min, and then the pressure is increased to 1.2 MPa at a rate of 0.2 MPa / min and held for 10 min before the assembly is completed.

[0048] S5. Selective Coating and Penetration: The nano-reinforced adhesive is selectively coated again on the nodes of the honeycomb core strip and the edge areas in contact with the aluminum panel, and penetrating is carried out by capillary action.

[0049] S6. Step-by-step curing: Place the assembled structural components in a curing oven, first cure at 80℃ for 60 minutes, then raise the temperature to 120℃ and cure for 120 minutes, and finally cool down to room temperature at a rate of 2℃ / min to complete the curing.

[0050] Example 3

[0051] A bonding method for aluminum honeycomb structural components includes the following steps:

[0052] S1. Composite Surface Modification Treatment: The bonding surfaces of the aluminum honeycomb core and aluminum panel are subjected to anodizing treatment. The anodizing voltage is set to 15V, the temperature is 22℃, and the electrolyte is a mixture of 4% oxalic acid solution and 17% sulfuric acid solution at a volume ratio of 1:4. The anodizing time is 20min. After anodizing, plasma etching is performed using a mixed gas source of argon and oxygen at a volume ratio of 5:1. The power is set to 400W, the vacuum degree is 0.07MPa, and the processing time is 5min. Then, a coupling agent (2% γ-aminopropyltriethoxysilane ethanol solution) is uniformly coated and dried at 90℃ for 12min to obtain the modified aluminum honeycomb core and aluminum panel.

[0053] S2. Preparation of nano-reinforced adhesive: Epoxy resin E-51 and curing agent 4,4'-diaminodiphenyl sulfone were mixed at a mass ratio of 100:30 to obtain a mixture. Then, 3.5% of the mass of the mixture was made of nano-alumina particles (particle size of 50 nm) and 1.0% of the mass of the mixture was made of dispersant polyethylene glycol. The mixture was then treated with an ultrasonic device with an ultrasonic power of 200 W, an ultrasonic frequency of 30 kHz, and an ultrasonic time of 25 min. The mixture was then stirred at a high speed of 3000 rpm for 17 min to obtain the nano-reinforced adhesive.

[0054] S3. Pre-curing of adhesive film: The nano-reinforced adhesive is uniformly coated on the inner surface of the modified aluminum panel, with a coating thickness of 0.2mm. Then, a constant temperature hot press is used for pre-curing. The temperature of the constant temperature hot press is 90℃, the pressure is 0.2MPa, and the time is 30min.

[0055] S4. Cellular Core Positioning and Gradient Pressurization: The modified cellular core is precisely placed on the pre-cured bottom layer adhesive film aluminum panel and assembled using gradient pressurization. The initial pressure during gradient pressurization is 0.4 MPa, the holding time is 7 min, and then the pressure is increased to 1.3 MPa at a rate of 0.2 MPa / min and held for 12 min before the assembly is completed.

[0056] S5. Selective Coating and Penetration: The nano-reinforced adhesive is selectively coated again on the nodes of the honeycomb core strip and the edge areas in contact with the aluminum panel, and penetrating is carried out by capillary action.

[0057] S6. Step-by-step curing: Place the assembled structural components in a curing oven, first cure at 85℃ for 75 minutes, then raise the temperature to 125℃ and cure for 135 minutes, and finally cool down to room temperature at a rate of 2.5℃ / min to complete the curing.

[0058] Comparative Example 1:

[0059] The difference from Example 1 is that the composite surface modification step is removed.

[0060] Comparative Example 2:

[0061] The difference from Example 1 is that the nano-alumina in the nano-reinforced adhesive is removed.

[0062] Comparative Example 3:

[0063] The difference from Example 1 is that the selective coating and penetration steps of S5 are removed.

[0064] The following performance tests were conducted on the aluminum honeycomb structures bonded in Examples 1, 2, and 3, and Comparative Examples 1, 2, and 3. The tensile shear strength of the bonded aluminum honeycomb structures in the examples and comparative examples at room temperature was tested according to GB7124-86; the 90° peel strength between plates at room temperature was tested according to GJB446-88; the 90° peel strength between the plate and core at room temperature was tested according to GJB130.8-86; and a high and low temperature cycling aging test was conducted according to GB / T2423.22. One cycle consisted of placing the aluminum honeycomb structure at -60°C for 2 hours, followed by a 1-hour transition at room temperature, and then placing it at 120°C for 2 hours. A total of 20 cycles were performed. The interfacial shear tensile strength was tested before and after aging, and the strength retention rate was calculated. The test results are shown in Table 1.

[0065] Table 1: Performance Tests of Aluminum Honeycomb Structures Bonded in Examples and Comparative Examples

[0066]

[0067] As can be seen from the table, the aluminum honeycomb structure components in Embodiments 1, 2, and 3 of the present invention, after being bonded, exhibit significantly higher tensile shear strength, peel strength, and strength retention rate after aging than the aluminum honeycomb structure components in Comparative Examples 1, 2, and 3 after bonding.

[0068] Composite surface modification treatment, through the synergistic effect of "anodic oxidation-plasma etching-coupling agent coating," forms a porous oxide film on the aluminum surface and introduces active groups. The coupling agent facilitates chemical bonding between the aluminum and the adhesive, significantly improving interfacial adhesion and tensile shear strength. This process also prevents interfacial delamination failure during peeling, enhances resistance to temperature-induced damage, and improves strength retention after high and low temperature aging. In adhesives with added nano-alumina, the nano-alumina particles are uniformly distributed through ultrasonic dispersion and high-speed stirring, enhancing the bulk strength of the adhesive layer. Combined with dispersants to inhibit agglomeration, this not only improves tensile shear strength but also shifts the peeling failure mode towards cohesive failure within the adhesive layer (rather than interfacial delamination). Furthermore, the nanoparticles alleviate internal stress caused by temperature changes, reducing cracking of the adhesive layer after aging and ensuring strength retention. Pre-curing the underlying adhesive film allows for initial cross-linking, fixing the adhesive layer thickness and reducing air bubbles. This ensures precise positioning of the honeycomb core, avoids uneven stress caused by assembly deviations, improves tensile shear strength stability, and makes the stress more uniform during peeling. It also reduces strength decay caused by defects during aging, further contributing to improved strength retention. Selective coating applies adhesive only to the nodes and edges of the honeycomb core, achieving precise penetration of the adhesive through capillary action. This avoids localized stress concentration caused by adhesive buildup within the honeycomb cells, ensuring both the amount of adhesive and bonding strength at key bonding areas, improving tensile shear and peel strength, and reducing the shrinkage stress of excess adhesive layers under temperature changes. This further ensures the strength retention rate after high and low temperature aging.

[0069] In summary, this invention achieves efficient and reliable bonding of aluminum honeycomb structural components through composite surface modification treatment, the addition of nano-adhesives, the construction of a "skeleton-filler" composite adhesive layer structure, and the synergistic innovation of gradient processes. It effectively solves the problems of weak interfacial bonding, poor environmental stability, and low peel strength in existing bonding technologies. The process is simple and suitable for industrial production.

[0070] The above are merely specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on the present invention to solve essentially the same technical problems and achieve essentially the same technical effects are all covered within the protection scope of the present invention.

Claims

1. A bonding method for aluminum honeycomb structural components, characterized in that, Includes the following steps: S1. Composite surface modification treatment: The bonding surfaces of the aluminum honeycomb core and the aluminum panel are sequentially subjected to anodizing, plasma etching and coupling agent coating to obtain the modified aluminum honeycomb core and aluminum panel; S2. Preparation of nano-reinforced adhesive: Epoxy resin E-51 and curing agent 4,4'-diaminodiphenyl sulfone are mixed at a mass ratio of 100:25~35 to obtain a mixture. Then, 2~5% of the mass of nano-alumina particles and 0.5~1.5% of the mass of the mixture are added. After treatment with ultrasonic equipment, the mixture is stirred at high speed to obtain nano-reinforced adhesive. S3. Pre-curing of adhesive film: The nano-reinforced adhesive is uniformly coated on the inner surface of the modified aluminum panel, with a coating thickness of 0.1~0.3mm. Then, a constant temperature hot press is used for pre-curing. The temperature of the constant temperature hot press is 80~100℃, the pressure is 0.1~0.3MPa, and the pre-curing time is 20~40min. S4. Cellular Core Positioning and Gradient Pressurization: The modified aluminum honeycomb core is precisely placed on the pre-cured bottom layer adhesive film aluminum panel and assembled using gradient pressurization. The initial pressure during gradient pressurization is 0.3~0.5MPa, the holding time is 5~10min, and then the pressure is increased to 1.2~1.5MPa at a rate of 0.2MPa / min and held for 10~15min before the process ends. S5. Selective Coating and Penetration: The nano-reinforced adhesive is selectively coated again on the nodes of the honeycomb core strip and the edge areas in contact with the aluminum panel, and penetrating by capillary action; S6. Step-by-step curing: Place the assembled structural components in a curing oven and cure them at 80~90℃ for 60~90min. Then, raise the temperature to 120~130℃ and cure for 120~150min. Finally, cool the components to room temperature at a rate of 2~3℃ / min to complete the curing process.

2. The bonding method for an aluminum honeycomb structure according to claim 1, characterized in that, In step S1, the electrolyte in the anodic oxidation is a mixture of oxalic acid solution with a mass concentration of 3-5% and sulfuric acid solution with a mass concentration of 15-20%, wherein the volume ratio of the oxalic acid solution with a mass concentration of 3-5% to the sulfuric acid solution with a mass concentration of 15-20% is 1:3-5, the oxidation voltage is set to 12-18V, the temperature is 18-25℃, and the oxidation time is 15-25min.

3. The bonding method for an aluminum honeycomb structure according to claim 1, characterized in that, In step S1, plasma etching uses a mixed gas source of argon and oxygen, wherein the volume ratio of argon to oxygen is 4~6:1, the power is 300~500W, the vacuum degree is 0.05~0.1MPa, and the processing time is 3~8min.

4. The bonding method for an aluminum honeycomb structure according to claim 1, characterized in that, In step S1, the coupling agent is an ethanol solution of γ-aminopropyltriethoxysilane with a mass concentration of 1.5-3%. After uniform coating with the coupling agent, the solution is dried at 80-100°C for 10-15 minutes.

5. The bonding method for an aluminum honeycomb structure according to claim 1, characterized in that, In S2, the particle size of the nano-alumina particles is 50~100nm; the dispersant is either triethanolamine or polyethylene glycol.

6. The bonding method for an aluminum honeycomb structure according to claim 1, characterized in that, In step S2, the ultrasonic power of the ultrasonic device is 100~300W, the ultrasonic frequency is 20~40kHz, and the ultrasonic time is 20~30min; the stirring rate is 2500~3500rpm, and the time is 15~20min.

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