Composite structure board as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of composite boards, and particularly relates to a composite structural board and a preparation method and application thereof. According to the method, the microstructure is constructed on the surface of the alloy substrate through hot stamping, so that the mechanical interlocking effect between the alloy substrate and a subsequent bonding material can be remarkably improved, and the bonding force between the alloy substrate and the subsequent bonding material is enhanced; the diffusion area between materials is increased, more channels are provided for mutual diffusion between atoms, and a firmer bonding interface can be formed; by means of a pulse electromagnetic field, primary attachment of the alloy substrate and the surface of the conductive metal foil is achieved; in the subsequent hot stamping process, atoms at the interface of the two plates are mutually diffused at high temperature and high pressure to form a thin-layer diffusion bonding area mainly comprising a solid solution, the metallurgical-mechanical composite bonding mode combines the advantages of mechanical interlocking and chemical bonding between atoms, the bonding strength of the composite structural plate is greatly improved, and the bonding strength of the composite structural plate is improved. Therefore, the structure is not prone to layering or falling off when bearing large external force, and stability and reliability of the structure are guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of composite panel technology, specifically relating to a composite structural panel, its preparation method, and its application. Background Technology

[0002] Titanium alloys are lightweight, high-strength metallic materials widely used in aerospace, medical equipment, automotive manufacturing, and marine engineering due to their excellent comprehensive properties. Because titanium alloys have poor room-temperature plasticity and cannot be cold-formed, they are typically manufactured using hot forming. However, hot forming processes are time-consuming, result in severe surface oxidation, and are costly. Furthermore, the cost of mold manufacturing often far exceeds the cost of the part itself, significantly limiting the wider application of titanium alloys.

[0003] Electromagnetic forming, a non-contact high-speed forming technology, utilizes pulsed magnetic fields to apply electromagnetic forces to conductive materials to achieve high-speed deformation. This technology boasts advantages such as easily controllable processing energy, simple mold structure, strong equipment versatility, and ease of automated production, making it widely used in industries such as aerospace and automotive manufacturing, and possessing environmentally friendly characteristics. Introducing electromagnetic forming technology into the processing of titanium alloy thin sheets holds promise for effectively solving the problem of long hot forming cycles. However, titanium alloys themselves have high resistivity, a significant layered structure, and poor electrical conductivity; their conductivity is only 1% of that of copper. This makes it almost impossible for titanium alloys to effectively induce electromagnetic fields and generate sufficient induced current, thus hindering the direct realization of electromagnetic forming.

[0004] In contrast, copper possesses excellent electrical conductivity (~58 MS / m), second only to silver among metals, while also being relatively inexpensive, offering good cost-effectiveness. Combining copper with titanium alloys can improve the conductivity of the titanium alloys to some extent. However, the conductivity of composite sheets obtained using traditional methods remains poor, reducing the efficiency of electromagnetic forming. Summary of the Invention

[0005] The purpose of this invention is to provide a composite structural plate, its preparation method, and its application. The method provided by this invention can further improve the conductivity of the alloy substrate, thereby improving the efficiency of electromagnetic forming.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing a composite structural plate, comprising the following steps: The alloy substrate is subjected to microimprinting to form an array of microstructures on its surface. A conductive metal foil is placed on the surface of the microstructure, and electromagnetic bonding and hot pressing are performed in sequence to obtain the composite structure plate.

[0007] Preferably, the electrical conductivity of the alloy substrate is less than 2.5 × 10⁻⁶. 6 S / m, wherein the alloy substrate comprises titanium alloy or stainless steel material; The thickness of the alloy substrate is 0.8~2mm.

[0008] Preferably, the microstructure includes pits or grooves; The trench has an inverted trapezoidal cross section, and adjacent trenches are separated by a ridge structure, the ridge structure having a trapezoidal cross section. The base angle of the trapezoid or the inverted trapezoid is independently 30~60°; The width is defined by the upper base or the lower base of the inverted trapezoid, the width-to-depth ratio of the trapezoid or the inverted trapezoid is 0.4 to 0.8, and the depth of the trapezoid or the inverted trapezoid is not greater than 0.8 times the thickness of the conductive metal foil.

[0009] Preferably, the pressure of the microimprinting process is 200~500MPa, and the holding time is 20~40min.

[0010] Preferably, the conductive metal foil includes at least one of copper foil, aluminum foil, iron foil, and nickel foil; The thickness of the conductive metal foil is 0.05~0.1mm.

[0011] Preferably, the electromagnetic parameters of the electromagnetic bonding include: a discharge voltage of 6~15kV, a discharge number of 3~8 times, and the process is carried out in a pulsed electromagnetic field.

[0012] Preferably, the hot pressing temperature is 400~500℃, the applied pressure is 50~200MPa, and the heat and pressure holding time is 10~30min.

[0013] Preferably, after hot pressing, the process further includes cooling and demolding the obtained sheet material; The cooling rate is ≤5℃ / min, and the cooling is carried out under pressure.

[0014] The present invention also provides a composite structure plate prepared by the preparation method described above, comprising an alloy substrate and a conductive metal foil stacked sequentially, wherein the alloy substrate and the conductive metal foil are metallurgically bonded together.

[0015] The present invention also provides the application of the composite structural plate described above in aerospace, automotive, energy or medical equipment.

[0016] This invention provides a method for preparing a composite structure plate, comprising the following steps: performing microimprinting on an alloy substrate to form an array of microstructures on the surface of the alloy substrate; placing a conductive metal foil on the surface of the microstructures, and sequentially performing electromagnetic bonding and hot pressing to obtain the composite structure plate.

[0017] In this invention, a microstructure is constructed on the surface of the alloy substrate through hot pressing, which significantly improves the mechanical interlocking effect between the alloy substrate and the subsequent bonding materials, enhancing the bonding force between them. On the other hand, it increases the diffusion area between materials, providing more channels for inter-atomic diffusion, which is conducive to forming a stronger bonding interface. With the help of pulsed electromagnetic field, the initial bonding of the alloy substrate and the conductive metal foil surface is achieved at room temperature. The pulsed electromagnetic field can generate a strong instantaneous magnetic field force, causing the metal foil to quickly approach the alloy substrate under the action of the magnetic field and expelling the residual gas between the two interfaces. During the subsequent hot pressing process, the atoms at the interface between the two undergo inter-diffusion under high temperature and high pressure, forming a thin-layer diffusion bonding region dominated by solid solution. This metallurgical-mechanical composite bonding method combines the advantages of mechanical interlocking and inter-atomic chemical bonding, greatly improving the bonding strength of the composite structure plate, making it less prone to delamination or detachment when subjected to large external forces during the subsequent electromagnetic forming process, ensuring the stability and reliability of the structure.

[0018] This invention employs electromagnetically assisted thermal composite imprinting technology to construct composite structural plates, offering significant advantages: First, the metal foil and alloy substrate are firmly bonded, resulting in high stress transfer efficiency and facilitating a more uniform stress distribution, thus preventing failures caused by localized stress concentration. Second, the stability of the deformation process is significantly improved, effectively suppressing defects such as cracking and wrinkling common in high-speed deformation. Third, this composite structural plate significantly improves the conductivity of the alloy substrate, enhancing electromagnetic forming efficiency and providing a novel electromagnetic forming process window for alloy plates. This promises to enable high-precision, high-efficiency, and low-cost manufacturing of complex structural components, providing an important technological path for expanding the application of alloys in more industrial fields.

[0019] This invention proposes using electromagnetically assisted thermal composite imprinting technology to prepare a uniform, dense, and highly bonded conductive metal foil layer on the surface of an alloy sheet, constructing a composite structural sheet. During the electromagnetic forming process, this conductive metal foil acts as a highly efficient electromagnetic energy coupling medium, strongly inducing pulsed magnetic fields and generating strong eddy currents, thereby producing a powerful Lorentz force. This Lorentz force acts directly on the metal layer and is effectively transferred to the alloy matrix through interfacial shear stress, driving the entire composite material to undergo high-speed, uniform plastic deformation. The composite structural sheet prepared by this process combines the high strength of the alloy with the high conductivity of the metal foil, achieving a complementary advantage of the two material properties. Attached Figure Description

[0020] Figure 1 A schematic flowchart of the preparation method provided by the present invention; Figure 2 This is a schematic diagram of the hot stamping die used in Example 1; Figure 3 The results show the bulging height test results of the composite structural plate obtained in Example 1. Detailed Implementation

[0021] A schematic flowchart of the preparation method provided by this invention is shown below. Figure 1 As shown below, in conjunction with Figure 1 The preparation method of the present invention will be described in detail.

[0022] This invention provides a method for preparing a composite structural plate, comprising the following steps: The alloy substrate is subjected to microimprinting to form an array of microstructures on its surface. A conductive metal foil is placed on the surface of the microstructure, and electromagnetic bonding and hot pressing are performed in sequence to obtain the composite structure plate.

[0023] The present invention performs microimprinting on an alloy substrate to form an array of microstructures on the surface of the alloy substrate.

[0024] In this invention, the electrical conductivity of the alloy substrate is preferably lower than 2.5 × 10⁻⁶. 6 S / m, the alloy substrate preferably comprises titanium alloy or stainless steel material; the thickness of the alloy substrate is preferably 0.8~2mm, specifically 0.8mm, 1.0mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2.0mm.

[0025] In this invention, prior to the microimprinting process, it is preferable to pretreat the alloy substrate. The pretreatment preferably includes sequential ultrasonic cleaning in acetone, ethanol, and water; the concentration of ethanol is preferably 99.999%; and the ultrasonic cleaning time in acetone, ethanol, and water is preferably 30 minutes. In this invention, ultrasonic cleaning in acetone removes organic contaminants from the alloy surface; ultrasonic cleaning in ethanol further dissolves residual organic impurities and provides a certain degree of dehydration; ultrasonic cleaning in water removes residual ethanol and any inorganic particulate impurities that may be present on the alloy surface, ensuring a clean and uncontaminated surface and providing a good base surface for subsequent processes. This pretreatment enables the alloy substrate surface to achieve an ideal clean state.

[0026] In this invention, the pressure of the microimprinting process is preferably 200~500MPa, specifically 200MPa, 300MPa, 400MPa, or 500MPa; the holding time is preferably 20~40min, specifically 20min, 30min, or 40min. In this invention, during the microimprinting process, a fixed die and a forming die are preferably used to fix the alloy, and a microstructured groove punch is used for microimprinting.

[0027] In this invention, the forming die is used to directly contact the bottom surface of the alloy substrate. Its main function is to ensure the flatness of the alloy substrate during the hot stamping process, providing a stable reference surface for the forming of the composite structure plate. It also participates in demolding after forming. The inner diameter of the fixing die is the same as that of the forming die. The fixing die is used to fix the position of the alloy substrate and conductive metal foil during the hot stamping process, preventing them from moving or deforming under pressure, thereby ensuring that the formed composite structure plate has an accurate shape, neat edges, and is free of defects such as burrs.

[0028] In this invention, the surface of the microstructured groove punch is processed with an array of nanostructured pits or microgrooves. By constructing a regularly distributed array of nano-pits or microgrooves on the surface of the alloy substrate through a nanostructured mold, the purpose is to increase the interfacial contact area between the alloy substrate and the conductive metal foil, enhance the mechanical interlocking effect, and improve the bonding strength.

[0029] In this invention, the materials of the fixed die, the forming die, and the microstructure groove punch are preferably materials with high strength, high thermal conductivity, and low coefficient of thermal expansion, specifically H13 steel.

[0030] In this invention, the microstructure preferably includes pits or grooves; the cross-section of the groove is preferably an inverted trapezoid, and adjacent grooves preferably include a ridge structure, the cross-section of the ridge structure being preferably trapezoidal; the base angles of the trapezoid and the inverted trapezoid are independently independent and preferably 30~60°; the width is based on the upper base or the lower base of the inverted trapezoid, and the depth-to-width ratio of the trapezoid or the inverted trapezoid is preferably 0.4~0.8, specifically 0.4, 0.5, 0.6, 0.7, or 0.8; the depth of the trapezoid or the inverted trapezoid is preferably not greater than 0.8 times the thickness of the conductive metal foil, specifically 0.6 times.

[0031] After obtaining the microstructure, the present invention places a conductive metal foil on the surface of the microstructure and performs electromagnetic bonding and hot pressing in sequence to obtain the composite structure plate.

[0032] In this invention, the conductive metal foil preferably includes at least one of copper foil, aluminum foil, iron foil and nickel foil; the thickness of the conductive metal foil is preferably 0.05~0.1mm, specifically 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm and 0.1mm.

[0033] In this invention, the conductive metal foil preferably undergoes pretreatment before use; the pretreatment preferably includes sequential acetone washing, acid washing, and water washing; the acetone washing is preferably performed under ultrasonic conditions; the dilute acid solution used for acid washing is preferably a nitric acid-alcohol solution with a mass concentration of 4%. In this invention, ultrasonic cleaning in acetone removes any organic contaminants that may be present on the surface of the metal foil; acid washing dissolves the oxide layer on the surface of the metal foil, restoring the active surface of the metal; multiple rinsings with deionized water remove residual dilute acid and other impurities, ensuring that the surface of the metal foil is clean and has good flatness, preparing it for subsequent lamination with an alloy substrate.

[0034] In this invention, the preferred electromagnetic parameters for electromagnetic bonding include: a discharge voltage of 6-15kV, specifically 6kV, 7kV, 8kV, 9kV, 10kV, 11kV, 12kV, 13kV, 14kV, and 15kV; and 3-8 discharge cycles, specifically 3, 4, 5, 6, 7, and 8 cycles. The electromagnetic bonding is preferably performed under a pulsed electromagnetic field. In this invention, the electromagnetic bonding is preferably performed using an electromagnetic coil punch. The electromagnetic coil punch is mainly used to achieve preliminary, large-area, uniform pre-bonding of the alloy substrate and conductive metal foil, eliminating interfacial gases and providing a good foundation for subsequent thermal diffusion bonding. In this invention, the material of the electromagnetic coil punch is preferably a material with high strength, high thermal conductivity, and low coefficient of thermal expansion, specifically H13 steel.

[0035] In this invention, a pulsed electromagnetic field is used to achieve initial bonding between the alloy substrate and the conductive metal foil surface at room temperature. The pulsed electromagnetic field generates a strong, instantaneous magnetic field, causing the metal foil to rapidly approach the alloy substrate under the influence of the magnetic field, and expelling any residual gas between the two. Through repeated, continuous impacts, a large-area pre-contact is achieved between the metal foil and the alloy substrate, providing a uniform interface foundation for subsequent hot-pressing processes. Uniform interface contact helps improve the overall bonding quality of the composite structure material, avoiding problems such as reduced bonding strength due to poor interface contact.

[0036] In this invention, the preferred hot pressing temperature is 400~500℃, specifically 400℃, 450℃, or 500℃; the preferred applied pressure is 50~200MPa, specifically 50MPa, 100MPa, 150MPa, or 200MPa; and the preferred heat and pressure holding time is 10~30min, specifically 10min, 20min, or 30min. In this invention, the hot pressing is preferably performed using a hot pressing die; the hot pressing die is a key thermo-mechanical composite module used for forming the final composite structure plate. It has an internal heating device that precisely controls the working temperature through resistance wire heating, while simultaneously applying pressure to the pre-bonded composite structure plate. Under the combined action of high temperature and high pressure, the interface atoms of the alloy substrate and the conductive metal foil are activated and interdiffusion occurs, ultimately forming a thin-layer diffusion bonding region dominated by solid solution, achieving metallurgical-grade bonding. In this invention, the material of the hot stamping die is preferably a material with high strength, high thermal conductivity and low coefficient of thermal expansion, specifically H13 steel.

[0037] In this invention, during the hot pressing process, the surface of the hot pressing die preferably includes an anti-adhesion coating to prevent the copper material from sticking together under high temperature and high pressure, ensuring smooth demolding and mold life; the anti-adhesion coating preferably includes diamond-like carbon (DLC) film, titanium nitride, or Teflon-based coating.

[0038] In this invention, by controlling the temperature of hot pressing, the metal foil undergoes thermoplastic flow, fully filling the pre-prepared nanoscale structure on the surface of the alloy substrate. Simultaneously, through controlled pressure, the atoms at the metal-alloy interface are activated under the combined effects of high temperature and high pressure, resulting in interdiffusion. With atomic diffusion, a thin diffusion bonding region dominated by solid solution gradually forms at the interface. This metallurgical-mechanical composite bonding method combines the advantages of mechanical interlocking and interatomic chemical bonding, significantly improving the bonding strength and stability of the composite structural plate.

[0039] In this invention, after hot pressing, the obtained sheet material is preferably cooled and depressurized for demolding; the cooling rate is preferably ≤5℃ / min; the cooling is preferably to a temperature below 150℃, and the cooling is preferably carried out under pressure, the pressure of which is preferably the same as the pressure of hot pressing.

[0040] In this invention, to ensure the interface remains stable during cooling and to avoid internal stress caused by excessively rapid cooling, which could lead to a decrease in interfacial bonding strength, the cooling rate must be precisely controlled while maintaining pressure. The composite structural plate is steadily cooled to below 150°C (cooling rate ≤ 5°C / min) to fully complete the atomic diffusion and bonding processes at the interface, forming a stable bonded structure. Subsequently, the pressure is released and the plate is carefully demolded to obtain a composite structural plate with both good conductivity and high electromagnetic forming efficiency. This composite structural plate combines the high strength of the alloy with the high conductivity of the conductive metal foil, and has broad application prospects in aerospace, electronic communications, and other fields.

[0041] The present invention also provides a composite structure plate prepared by the preparation method described above, comprising an alloy substrate and a conductive metal foil stacked sequentially, wherein the alloy substrate and the conductive metal foil are metallurgically bonded together.

[0042] The present invention also provides the application of the composite structural plate described above in aerospace, automotive, energy or medical equipment.

[0043] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0044] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0045] Example 1 A titanium alloy substrate with a thickness of 1.2 mm was ultrasonically cleaned in acetone for 30 min, ultrasonically cleaned in ethanol solution (concentration of 99.999%) for 30 min, and ultrasonically cleaned in deionized water for 30 min to obtain a pretreated titanium alloy substrate. The pretreated titanium alloy obtained above was fixed using a fixed die and a forming die, and then micro-imprinted using a microstructured groove punch. The applied pressure was 400 MPa, and the holding time was 30 min. The fixed die, forming die, and microstructured groove punch were all made of H13 steel. An array of groove structures was formed on the surface of the titanium alloy (where the depth-to-width ratio T:W of the trapezoidal and inverted trapezoidal shapes was 0.6, the depth T was 0.6 times the copper foil thickness, and the base angle θ was 30°). A schematic diagram of the microstructured groove punch is shown below. Figure 2 (as shown) A copper foil with a thickness of 0.5 mm was ultrasonically cleaned in acetone for 30 min; the copper foil was then cleaned with a 4% dilute acid solution; finally, it was rinsed multiple times with deionized water to obtain the pretreated copper foil. The pretreated copper foil is placed on the surface of the microstructure, and electromagnetic bonding and hot pressing are performed sequentially. The electromagnetic bonding is performed using an electromagnetic coil punch made of H13 steel, with the following parameters: the discharge voltage is set to 8kV, and the pulsed electromagnetic field is used to discharge 8 times. Then, it is placed in a hot pressing device for hot pressing, using a hot pressing punch made of H13 steel, with the temperature controlled at 450℃, a pressure of 150MPa applied, and the temperature and pressure maintained for 20 minutes. Maintaining the pressure of hot pressing, the hot-pressed sheet is steadily cooled to below 150°C at a cooling rate of 2°C / min. Subsequently, the pressure is released and the sheet is demolded to obtain a titanium-copper composite structure sheet.

[0046] Electromagnetic free bulging experiments were conducted on the titanium-copper composite structural plate, and compared with those of a single titanium alloy sheet under the same process. The electromagnetic pulse forming equipment used was an EMF_20 / 20 type magnetic pulse forming machine with a rated voltage of 20kV, a constant capacitance of 100μF, and a maximum discharge energy of 20kJ. The results at a discharge energy of 12kJ are as follows: Figure 3 As shown, the maximum bulging height of the composite structural plate provided by the present invention is 7.32 cm, while the maximum bulging height of a single titanium alloy plate is 3.08 cm. It can be seen that the bulging height of the composite structural plate provided by the present invention is higher than that of the titanium alloy thin plate, indicating that the titanium-copper composite structural plate has better formability.

[0047] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a composite structural panel, characterized in that, Includes the following steps: The alloy substrate is subjected to microimprinting to form an array of microstructures on its surface. A conductive metal foil is placed on the surface of the microstructure, and electromagnetic bonding and hot pressing are performed in sequence to obtain the composite structure plate.

2. The preparation method according to claim 1, characterized in that, The conductivity of the alloy substrate is less than 2.5 × 10⁻⁶. 6 S / m, wherein the alloy substrate comprises titanium alloy or stainless steel material; The thickness of the alloy substrate is 0.8~2mm.

3. The preparation method according to claim 1, characterized in that, The microstructure includes pits or grooves; The trench has an inverted trapezoidal cross section, and adjacent trenches are separated by a ridge structure, the ridge structure having a trapezoidal cross section. The base angle of the trapezoid or the inverted trapezoid is independently 30~60°; The width is defined by the upper base or the lower base of the inverted trapezoid, the width-to-depth ratio of the trapezoid or the inverted trapezoid is 0.4 to 0.8, and the depth of the trapezoid or the inverted trapezoid is not greater than 0.8 times the thickness of the conductive metal foil.

4. The preparation method according to claim 1, characterized in that, The pressure for the microimprinting process is 200~500MPa, and the holding time is 20~40min.

5. The preparation method according to claim 1, characterized in that, The conductive metal foil includes at least one of copper foil, aluminum foil, iron foil, and nickel foil; The thickness of the conductive metal foil is 0.05~0.1mm.

6. The preparation method according to claim 1, characterized in that, The electromagnetic parameters of the electromagnetic bonding include: a discharge voltage of 6~15kV, a discharge number of 3~8 times, and the process is carried out in a pulsed electromagnetic field.

7. The preparation method according to claim 1, characterized in that, The hot pressing temperature is 400~500℃, the applied pressure is 50~200MPa, and the heat and pressure holding time is 10~30min.

8. The preparation method according to claim 1, characterized in that, After hot pressing, the process also includes cooling and demolding the resulting sheet material; The cooling rate is ≤5℃ / min, and the cooling is carried out under pressure.

9. The composite structural plate prepared by the preparation method according to any one of claims 1 to 8, characterized in that, It includes an alloy substrate and a conductive metal foil stacked sequentially, wherein the alloy substrate and the conductive metal foil are metallurgically bonded together.

10. The application of the composite structural panel of claim 9 in aerospace, automotive, energy or medical equipment.

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