Composite material laminate containing corrugated metal interlayer and preparation method of composite material laminate

Abstract

The invention discloses a composite material laminate containing a corrugated metal interlayer and a preparation method thereof, the composite material laminate comprises a middle metal corrugated board, an upper composite material structure layer and a lower composite material structure layer, the preparation method comprises the following steps: (1) pretreating the metal corrugated board and a composite material prepreg; (2) the pretreated metal corrugated board is subjected to acid pickling modification; (3) modifying the modified metal corrugated board by using a silane coupling agent; (4) paving the composite material prepreg on the surface of the modified metal corrugated board; and (5) preparing the composite laminate in a hot pressing manner. On the basis of the composite material, the middle layer metal foil is added, the air tightness problem is solved, and meanwhile the lightweight effect of the composite material is reserved to the maximum extent; and the three-layer symmetrical structure of the middle high-expansion-coefficient metal foil is limited by the inner and outer low-expansion-coefficient composite materials, so that the interface stress value can be effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of fiber metal laminate technology, and more specifically to a composite material laminate containing corrugated metal interlayers and its preparation method. Background Technology

[0002] With the continuous development of aerospace technology, the performance requirements for aircraft and their key components are increasing, especially in critical structures such as propellant tanks. Besides mechanical performance requirements, lightweighting and airtightness have become core design objectives. Traditional propellant tanks mainly use metallic materials, such as aluminum alloys or titanium alloys, which provide good mechanical properties and airtightness in cryogenic environments. However, due to the isotropic nature of metallic materials, their weight is relatively large, limiting the payload capacity of aircraft. Furthermore, with the development of reusable launch vehicles (RLVs) and other spacecraft, tanks must not only meet the requirements of high airtightness and lightweighting, but also maintain good structural performance during multiple launches and recoveries. Against this backdrop, high specific strength and high specific stiffness carbon fiber reinforced resin matrix composites have become ideal candidate materials for propellant tanks due to their excellent lightweight properties. However, to date, cryogenic composite material tanks have not been widely adopted in practical applications, one major challenge being propellant (gas and liquid) leakage. While carbon fiber composites possess excellent mechanical properties, the presence of microcracks or fiber breakage in the matrix material can easily lead to propellant leakage during long-term service, posing a significant safety hazard to propellant tanks. To overcome these limitations of all-carbon fiber composites, a "carbon fiber composite-metal liner" double-layer structure combining a metal liner with a lightweight composite shell has been widely used in the gas cylinder field. However, due to the significant difference in thermal expansion coefficients between the metal and composite materials (approximately 10 times), interfacial delamination failure is likely to occur under extreme low-temperature to room-temperature cycling conditions. Furthermore, the overall lightweight effect is limited by the weight of the metal liner, which greatly restricts its application in propellant tanks.

[0003] To overcome these technical challenges, researchers have attempted to enhance the airtightness and interfacial bonding of composite materials by improving their design and manufacturing processes. For example, introducing nanoparticles (patent CN118165442A) or modifying materials (patent CN117430943A) into composite materials can improve their airtightness and durability. However, while these improvements have enhanced gas penetration resistance to some extent, they are only effective and still cannot fundamentally meet the requirements of lightweight and long-life tank materials for spacecraft. Summary of the Invention

[0004] In view of this, the present invention provides a "composite-corrugated metal foil-composite" sandwich structure based on resin-based composite materials and metal foil and its preparation method, which is mainly applied to the design and manufacturing of structural components in aerospace and other fields with requirements for high rigidity, airtightness and lightweight.

[0005] This invention addresses the airtightness issue by adding an intermediate metal foil layer to a composite material, while maximizing the lightweight effect of the composite. The three-layer symmetrical structure, with low-expansion-coefficient composites on the inner and outer sides restricting the high-expansion-coefficient metal foil in the middle, effectively reduces interfacial stress. The corrugated structure provides multi-directional stiffness support, significantly improving the out-of-plane stiffness and buckling resistance of the structure. Simultaneously, the corrugated configuration strengthens the mechanical interlocking effect between the metal and the composite, reducing the risk of interfacial delamination and overcoming the bottleneck of interfacial failure under high and low temperature cyclic loading. This structure cleverly combines the high airtightness of the metal material, the high stiffness of the corrugated structure, and the lightweight characteristics of the composite material, providing a structural design solution that simultaneously achieves high airtightness, lightweight, and high stiffness. It is widely applicable to fields with strict requirements for airtightness, lightweight, and weight reduction, such as propellant tanks, pressure vessels, and composite material molds.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A composite material laminate containing corrugated metal sandwich panels includes: an intermediate corrugated metal sheet and upper and lower composite material structural layers. The thickness of the metal corrugated sheet is ≤0.1mm, and the ratio of the vertical height h of the corrugated structure crest to trough to the wavelength λ is h / λ≥0.25.

[0007] Preferably, the corrugated metal sheet is stainless steel foil or titanium alloy foil; The composite material structural layer is formed by curing resin and fiber.

[0008] Preferably, the fiber is carbon fiber material and the resin is epoxy resin.

[0009] A method for preparing a composite material laminate containing corrugated metal sandwich panels includes the following steps: (1) Pretreatment of metal corrugated sheets and composite prepregs; (2) The pretreated metal corrugated sheet is acid-washed and modified; (3) The modified metal corrugated sheet is modified with a silane coupling agent; (4) Lay the composite prepreg onto the surface of the modified metal corrugated sheet; (5) The composite material laminate is prepared by hot pressing.

[0010] Preferably, the pretreatment of the metal corrugated sheet includes: cutting the metal corrugated sheet to the target size, and then ultrasonically treating the metal corrugated sheet with anhydrous ethanol and deionized water in sequence using an ultrasonic cleaner. The purpose of this step is to remove surface contamination of the material caused by grinding or processing and transportation.

[0011] Preferably, the acid pickling modification includes: when the metal corrugated sheet is stainless steel foil, placing the metal corrugated sheet in a 1.5 mol / L hydrochloric acid solution and allowing it to stand at a constant temperature of 60°C for 60 minutes; when the metal corrugated sheet is titanium foil, placing the metal corrugated sheet in a 0.5 mol / L hydrochloric acid solution and allowing it to stand at a constant temperature of 40°C for 40 minutes to allow the surface to fully react with the hydrochloric acid. The purpose of this step is to remove the oxide layer and impurities from the surface.

[0012] Preferably, after pickling, the pickled metal corrugated sheet is sequentially cleaned with deionized water and anhydrous ethanol for 30 minutes, and then dried. The purpose of this step is to remove residual hydrochloric acid from the surface; Preferably, the modification of the silane coupling agent includes: immersing the metal corrugated plate in the silane coupling agent hydrolysate and performing ultrasonic treatment for 30 minutes; then, removing the metal corrugated plate and drying it at 60°C for 12 hours, so that the coupling agent hydrolysate immersed in the surface can fully react with the metal; and then cooling it to room temperature to complete the silane coupling agent surface coating treatment.

[0013] Preferably, the silane coupling agent hydrolysate is prepared by the following method: ethanol and deionized water are mixed at a mass ratio of 95:5, and then 4 wt% of the silane coupling agent is added to the mixed solvent. The silane coupling agent is fully dissolved by magnetic stirring. Then, acetic acid is added to adjust the pH to 5 to promote the hydrolysis reaction of the silane coupling agent. The mixture is then stirred for 30 minutes to obtain the silane coupling agent hydrolysate.

[0014] Preferably, in step (4), the composite prepreg is cut to the appropriate width and laid into the grooves on both sides of the metal corrugated sheet; after being laid flat, the entire prepreg sheet can be laid on the surface. When laying, attention should be paid to the flatness between layers and the fiber arrangement direction to avoid wrinkles and bubbles. Multiple layers are laid according to design requirements. The laying direction and sequence of each layer are strictly in accordance with the design requirements to ensure the mechanical properties of the finished product.

[0015] Preferably, the hot pressing is performed using a hot press or a hot press tank, and the hot pressing parameters are determined based on the composite prepreg.

[0016] The laminate layup in this invention can be designed according to requirements, and the curing process parameters can be used according to the recommendations of the composite prepreg supplier. It is recommended to use a medium-temperature curing prepreg (YHP725 / T700), with the following hot-pressing parameters: recommended pressure is 1 MPa, with a recommended pressure range of 0.8-1.2 MPa; recommended temperature is 140℃, with a recommended temperature range of 120-150℃; recommended holding time is 120 min, with a recommended range of 90-150 min.

[0017] Another object of the present invention is to provide a composite material laminate containing a corrugated metal interlayer, which is prepared by the above-mentioned method for preparing a composite material laminate containing a corrugated metal interlayer.

[0018] This invention proposes a novel sandwich-layered composite structure of "composite material-corrugated metal foil-composite material." A micron-level metal foil layer is introduced between the composite material layers. The metal foil possesses excellent airtightness, effectively preventing gas from passing through the composite material layers and ensuring the structure's airtightness. This maximizes lightweight design while maintaining product airtightness. Furthermore, by using low-expansion-coefficient composite materials (such as carbon fiber composites) on both sides, the free expansion of the high-expansion-coefficient metal foil (such as stainless steel foil) in the middle is restricted. This transforms the interfacial stress from a single tensile stress into a more complex tensile-compressive composite stress state, effectively reducing interfacial stress values ​​under high and low temperature cycling environments and minimizing the risk of interfacial failure. Simultaneously, the corrugated structure reinforces the mechanical interlocking effect with the composite material, reducing the risk of interfacial delamination. The corrugated structure provides multi-directional stiffness support, significantly improving the structure's compressive and impact resistance. Through the designed three-layer symmetrical structure and the synergistic effect of the materials, the airtightness and lightweighting problems in traditional propellant tanks and other structures with high airtightness requirements are solved.

[0019] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects: 1. Air tightness This invention significantly improves the airtightness of the structure by introducing a micron-sized metal foil layer between the composite material layers. The addition of the metal foil effectively prevents gas leakage from pure composite structures that are prone to occur during long-term service due to matrix cracks or fiber breakage. Gas permeability tests were conducted according to standard GB / T1038.1—2022 using the differential pressure method, and the test results are as follows... Figure 4 As shown, the permeation pressure of the corrugated metal sandwich laminate is significantly lower than that of the pure composite material laminate. This technology is particularly suitable for applications such as spacecraft propellant tanks that require high airtightness under extreme temperatures and pressures, ensuring the safety and reliability of the product.

[0020] 2. High stiffness The "composite material-metal foil-composite material" sandwich structure proposed in this invention significantly improves bending and impact resistance with its corrugated structure. Bending tests were conducted according to standard ASTM D7264M, and the test results are as follows: Figure 5 As shown, the flexural strength and flexural modulus of the laminate containing corrugated metal sandwich panels are significantly higher than those containing flat metal sandwich panels and pure composite material laminates. Furthermore, the design of the inner and outer composite materials restricting the intermediate metal foil effectively reduces interfacial stress and prevents interfacial failure in high and low temperature cycling environments. Compared to traditional double-layer structures, it exhibits extremely high stability and durability, ensuring long-term service life of the product in alternating high and low temperature environments. It is suitable for spacecraft components requiring high reliability and long service life, deep-sea equipment, and other structural components requiring resistance to extreme environments.

[0021] 3. Lightweight This invention achieves maximum lightweight design while ensuring airtightness and structural strength. Compared to the traditional two-layer structure of a metal liner and a composite material shell, the use of a metal foil interlayer instead of a heavy metal liner not only reduces the weight of the structure but also retains the high specific strength advantage of composite materials. This lightweight performance is of great significance to fields such as aerospace and automotive manufacturing, which have strict requirements for weight reduction, and helps to improve carrying capacity, reduce fuel consumption, and improve the efficiency of the overall system.

[0022] 4. Applicability The "composite-metal foil-composite" sandwich structure of this invention is also applicable to other fields requiring high airtightness, lightweight, and long service life, such as composite material molds, pressure vessels, and aerospace structural components. This technology has promotional value in multiple industries, providing an efficient and reliable solution for product design in related fields, and is expected to be applied in large-scale production. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the product structure of the present invention.

[0025] Figure 2 This is an overall flowchart of the method for preparing composite material laminates containing corrugated metal interlayers.

[0026] Figure 3 Hot pressing process curves for preparing corrugated metal sandwich composite laminates.

[0027] Figure 4 This is a comparison of the airtightness test results of composite laminates with corrugated metal interlayers and composite laminates.

[0028] Figure 5 A comparison of the bending properties of composite laminates with corrugated metal sandwich panels, composite laminates, and composite laminates with flat metal sandwich panels.

[0029] Figure 1 In the middle: 1-metal corrugated sheet; 2-composite structural layer one; 3-composite structural layer two. Detailed Implementation

[0030] 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. Example 1

[0031] See Figure 1 This embodiment provides a composite material laminate containing corrugated metal sandwich panels. The entire structure is divided into two parts: the middle layer 1 is a metal corrugated plate, and the two sides 2 and 3 are composite material structural layer one and composite material structural layer two. The corrugated metal sheet 1 is made of 304 stainless steel foil with a thickness of 0.1 mm. The vertical height h between the crests and troughs of the corrugated structure is 1.2 mm, and the wavelength λ is 4.15 mm. Composite material structural layer 2 and composite material structural layer 3 are formed by curing epoxy resin and carbon fiber, with the specific material grade being YHP725 / T700. The composite material layup is [0°]5, and the nominal thickness of each prepreg layer is 0.125 mm. After curing, the actual thickness of the composite material layer is 1.78 mm. Example 2

[0032] This embodiment provides a composite material laminate with a corrugated metal sandwich layer. The entire structure is divided into two parts: the middle layer 1 is a corrugated metal plate, and the two sides 2 and 3 are composite material structural layer one and composite material structural layer two, respectively. The corrugated metal sheet 1 is made of 304 stainless steel foil with a thickness of 0.1 mm. The vertical height h between the crests and troughs of the corrugated structure is 0.5 mm, and the wavelength λ is 1.73 mm. Composite material structural layer 1 (2) and composite material structural layer 2 (3) are formed by curing epoxy resin and carbon fiber, with the specific material grade being YHP725 / T700. The composite material layup is [0° / 90°]2 / [0°]4, with a nominal thickness of 0.125 mm for each prepreg layer. The actual thickness of the composite material layer after curing is 2.05 mm. Example 3

[0033] This embodiment provides a method for preparing composite material laminates containing corrugated metal interlayers as described in Examples 1 and 2, including the following steps: (1) Cut the metal corrugated strip into corrugated sheets of the target size, and then use anhydrous ethanol and deionized water in sequence to ultrasonically treat the corrugated sheets with an ultrasonic cleaner. (2) After completing the pretreatment, prepare a 1.5 mol / L hydrochloric acid solution, put the corrugated board into the hydrochloric acid solution, and keep it at 60℃ for 60 min to allow the surface of the corrugated board to fully react with the hydrochloric acid. Then, wash the acid-washed corrugated board with deionized water and anhydrous ethanol for 30 min in sequence, and then dry it. (3) To prepare the silane coupling agent hydrolysate, first prepare the solvent base by mixing ethanol and deionized water at a mass ratio of 95:5. Then, add 4 wt% of the silane coupling agent KH-550 (γ-aminopropyltriethoxysilane) to the mixed solvent system and use magnetic stirring to fully dissolve the silane coupling agent. Add acetic acid to the above solution to adjust the pH to 5 to promote the hydrolysis reaction of the silane coupling agent. Stir the solution rapidly for 30 min to obtain the silane coupling agent hydrolysate. (4) Immerse the metal corrugated sheet in the silane coupling agent hydrolysate and perform ultrasonic treatment for 30 minutes to ensure that the silane coupling agent hydrolysate can fully wet the surface of the corrugated sheet; then, take out the corrugated sheet and place it in an oven at 60°C for 12 hours so that the coupling agent hydrolysate immersed in the surface of the corrugated sheet can fully react with the metal; then cool to room temperature to complete the silane coupling agent surface coating treatment of the corrugated sheet.

[0034] (5) Cut the prepreg to the appropriate width and lay it into the grooves on both sides of the corrugated board; after laying it flat, the surface can be covered with whole sheets of prepreg. When laying, pay attention to the flatness between layers and the fiber arrangement direction to avoid wrinkles and air bubbles. Lay multiple layers according to design requirements. The laying direction and sequence of each layer should be strictly in accordance with the design requirements to ensure the mechanical properties of the finished product.

[0035] (6) After the paving is completed, the entire structure is placed in the mold and cured by hot pressing. The curing process parameters are determined based on the composite prepreg to ensure that the resin is completely cured and forms a stable composite structure.

[0036] In this embodiment, the curing parameters are: temperature increases to 140°C at a rate of 2°C per minute, holding at that temperature for 120 minutes, and curing pressure of 1 MPa.

[0037] 1. Existing composite material structures often experience gas leakage during service due to microscopic cracks or fiber breakage, affecting their airtightness. This invention introduces a micron-level metal foil layer in the middle of the composite material layers, innovatively solving the application bottleneck of composite materials in fields with high airtightness requirements, and fundamentally solving the airtightness problem that occurs during product service.

[0038] 2. Traditional composite-metal bilayer structures are prone to interfacial stress concentration in extreme temperature environments, leading to interlayer separation and failure. This invention introduces a micron-sized metal foil as an intermediate layer into the composite material layers, forming a sandwich-like layered structure. The low-expansion-coefficient composite material layers on both the inner and outer sides effectively limit the thermal expansion of the intermediate metal foil, successfully transforming the interfacial stress from simple tensile stress to a combined tensile-compressive stress state. This fundamentally reduces the risk of interfacial failure and ensures the stability and reliability of the structure under extreme temperature conditions. This innovative design overcomes the failure bottleneck of traditional composite-metal bilayer structures in ultra-low temperature to room temperature cycling environments, improving the service life and adaptability of composite materials.

[0039] 3. The intermediate metal foil adopts a corrugated geometric structure to provide multi-directional stiffness support. In particular, the corrugated units form continuous support in the thickness direction, which improves the bending and impact resistance of the laminate. Compared with the planar structure, it can further enhance the mechanical interlocking effect with the composite material, enhance the interlayer bonding force, and significantly improve the stability of the thin-walled structure.

[0040] 4. This invention uses micron-sized metal foil instead of the traditional thick metal liner, minimizing the weight of the structure while ensuring airtightness. It successfully balances the demands for lightweight and high performance, enabling this sandwich composite structure to not only provide stable airtightness in extreme environments but also offer significant lightweight advantages.

[0041] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0042] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those 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 invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A composite material laminate containing a corrugated metal sandwich layer, characterized in that, include: The middle metal corrugated sheet and the upper and lower composite material structural layers; The thickness of the metal corrugated sheet is ≤0.1mm, and the ratio of the vertical height h of the corrugated structure crest to trough to the wavelength λ is h / λ≥0.

25.

2. The composite material laminate containing a corrugated metal sandwich panel according to claim 1, characterized in that, The corrugated metal sheet is made of stainless steel foil or titanium alloy foil. The composite material structural layer is formed by curing resin and fiber.

3. A composite material laminate containing a corrugated metal sandwich panel according to claim 2, characterized in that, The fiber is carbon fiber material, and the resin is epoxy resin.

4. A method for preparing a composite material laminate containing a corrugated metal interlayer as described in claim 3, characterized in that, Includes the following steps: (1) Pretreatment of metal corrugated sheets and composite prepregs; (2) The pretreated metal corrugated sheet is acid-washed and modified; (3) The modified metal corrugated sheet is modified with a silane coupling agent; (4) Lay the composite prepreg onto the surface of the modified metal corrugated sheet; (5) The composite material laminate is prepared by hot pressing.

5. The method for preparing a composite material laminate containing a corrugated metal interlayer according to claim 4, characterized in that, The pretreatment of the metal corrugated sheet includes: cutting the metal corrugated sheet into the target size, and then using anhydrous ethanol and deionized water in sequence to perform ultrasonic treatment on the metal corrugated sheet by an ultrasonic cleaner at an ultrasonic frequency of 40Hz.

6. The method for preparing a composite material laminate containing a corrugated metal interlayer according to claim 4, characterized in that, The pickling modification includes: when the metal corrugated sheet is stainless steel foil, placing the metal corrugated sheet in a 1.5 mol / L hydrochloric acid solution and keeping it at a constant temperature of 60°C for 60 min; when the metal corrugated sheet is titanium foil, placing the metal corrugated sheet in a 0.5 mol / L hydrochloric acid solution and keeping it at a constant temperature of 40°C for 40 min to allow the surface to fully react with the hydrochloric acid.

7. The method for preparing a composite material laminate containing a corrugated metal interlayer according to claim 4, characterized in that, The modification of the silane coupling agent includes: immersing the metal corrugated plate in the silane coupling agent hydrolysate and subjecting it to ultrasonic treatment for 30 minutes; then, removing the metal corrugated plate and drying it at 60°C for 12 hours, followed by cooling it to room temperature.

8. The method for preparing a composite material laminate containing a corrugated metal sandwich panel according to claim 7, characterized in that, The silane coupling agent hydrolysate is prepared by the following method: ethanol and deionized water are mixed at a mass ratio of 95:5, and then 4 wt% of silane coupling agent is added to the mixed solvent. The silane coupling agent is fully dissolved by magnetic stirring. Then acetic acid is added to adjust the pH to 5, and the mixture is stirred for 30 minutes to obtain the silane coupling agent hydrolysate.

9. The method for preparing a composite material laminate containing a corrugated metal interlayer according to claim 4, characterized in that, The hot pressing is performed using a hot press or a hot press tank, and the hot pressing parameters are determined based on the composite material prepreg.

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