Preparation process of low-carbon high-strength aluminum sandwich plate

Abstract

This invention provides a manufacturing process for low-carbon, high-strength aluminum sandwich panels, belonging to the field of aluminum sandwich panel technology. The process includes the following steps: S1: Raw material preparation and smelting, preparing recycled aluminum raw materials, smelting and adding alloying elements and rare earth elements to obtain a recycled aluminum alloy for preparing the sandwich panel's face sheet; S2: Core layer preform preparation, using recycled aluminum as the main raw material to prepare a porous metal core layer preform; S3: Integrated composite molding, placing the core layer preform and face sheet material in a molding environment; S4: Carbon footprint binding, calculating and generating carbon footprint data for the entire life cycle of the sandwich panel. Through a raw material grading and control system and rare earth element synergistic optimization technology, a high proportion of recycled aluminum from complex sources is successfully transformed into a structural material with stable performance. While ensuring that the core mechanical properties of the product fully meet or even exceed those of traditional virgin aluminum alloy products, a significant reduction in carbon emissions throughout the entire life cycle is achieved.

Description

Technical Field

[0001] This invention belongs to the field of aluminum sandwich panel technology, and in particular to a preparation process for a low-carbon, high-strength aluminum sandwich panel. Background Technology

[0002] With the advancement of global carbon neutrality goals and the deepening of green supply chain management, lightweighting and decarbonization have become core development trends in high-end manufacturing. Aluminum alloy sandwich panels (such as aluminum honeycomb and aluminum foam sandwich panels) are widely used in new energy vehicles, aerospace, electronic communications and green building fields due to their excellent specific strength, specific stiffness and multi-functional potential.

[0003] While using recycled aluminum can significantly reduce carbon emissions in traditional high-end applications, the complex sources, fluctuating composition, and high impurity content of recycled aluminum lead to poor purity and unstable performance in the molten aluminum. Current technologies struggle to consistently achieve performance levels sufficient for precision structural components with a high proportion of recycled aluminum without significantly increasing costs. This limits recycled aluminum to low-end castings and prevents its large-scale application in high-end sandwich panels, where high performance and ultra-low carbon emissions are difficult to achieve simultaneously. Traditional aluminum sandwich panels often use organic adhesives to connect the panels and core layers. This method suffers from inherent defects such as limited interfacial bonding strength, poor aging resistance, poor high-temperature resistance, and insufficient fire resistance, affecting the structural safety and reliability of the product during long-term service and in harsh environments.

[0004] In view of the above problems, this invention proposes a manufacturing process for low-carbon, high-strength aluminum sandwich panels. Through a raw material classification and control system and rare earth element synergistic optimization technology, a high proportion of recycled aluminum from complex sources is successfully transformed into a structural material with stable performance. While ensuring that the core mechanical properties of the product fully meet or even exceed those of traditional virgin aluminum alloy products, a significant reduction in carbon emissions throughout the entire life cycle is achieved. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in existing technologies by proposing a manufacturing process for low-carbon, high-strength aluminum sandwich panels.

[0006] The objective of this invention can be achieved through the following technical solutions: A manufacturing process for a low-carbon, high-strength aluminum sandwich panel includes the following steps: S1: Raw material preparation and smelting: Prepare recycled aluminum raw materials, smelt and add alloying elements and rare earth elements to obtain recycled aluminum alloy, which is used to prepare the panel of sandwich panel. S2: Core layer preform preparation, using recycled aluminum as the main raw material to prepare a porous metal core layer preform; S3: Integrated composite molding, the core layer preform and the panel material are placed in the molding environment, and under the combined action of heat and force, the panel and the core layer are bonded together through interface metallurgy or micro-melting bonding to form an integrated composite blank. S4: Carbon footprint binding, calculate and generate carbon footprint data for the entire life cycle of the sandwich panel, and uniquely bind the data to the product entity.

[0007] Preferably, in step S1, the recycled aluminum alloy melt contains, by weight percentage: 8.0-12.0% Si, 1.5-3.0% Cu, 0.03-0.25% rare earth elements, with the balance being Al, and the proportion of the recycled aluminum raw material to the total aluminum input is not less than 70 wt%.

[0008] Preferably, the rare earth element is a combination of lanthanum (La) and cerium (Ce), and the recycled aluminum raw material is subject to a graded and classified management process based on its source, composition and cleanliness.

[0009] Preferably, in step S2, the porous metal core preform is a foamed aluminum preform or an aluminum honeycomb core. When preparing the foamed aluminum preform, the raw materials contain a foaming agent and a cell stabilizer, and the cell stabilizer contains rare earth oxides.

[0010] Preferably, the integrated composite in step S3 involves simultaneous foaming and composite formation. The core layer preform containing the foaming agent is placed in a mold, and the melt for the panel is poured in, thus completing the core layer foaming and interface composite formation simultaneously under pressure.

[0011] Preferably, in step S3, the bonding surface of the panel material is roughened before lamination to enhance the interfacial bonding strength. The roughening pretreatment includes at least one of laser roughening, micro-arc oxidation, or chemical etching.

[0012] Preferably, in step S4, the carbon footprint data is accessed by scanning the QR code attached to the product or reading the RFID tag, and the data includes at least: the proportion of recycled aluminum raw materials, the energy consumption of key processes, and the carbon emission intensity per unit product.

[0013] Preferably, the core layer of the sandwich panel has a non-uniform density distribution, forming a mechanical property gradient structure; the core layer integrates functional units, which are sealed phase change material capsules or interconnected microfluidic channels.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a manufacturing process for a low-carbon, high-strength aluminum sandwich panel. Through a raw material classification and control system and rare earth element synergistic optimization technology, it successfully transforms a high proportion of recycled aluminum from complex sources into a structural material with stable performance. While ensuring that the core mechanical properties of the product fully meet or even exceed those of traditional virgin aluminum alloy products, it achieves a significant reduction in carbon emissions throughout the entire life cycle.

[0015] 2. The present invention provides a manufacturing process for a low-carbon, high-strength aluminum sandwich panel. By employing an integrated micro-melting / metallurgical composite molding technology, a direct metal bonding interface without organic adhesives is formed between the panel and the core layer. This interface exhibits extremely high bonding strength and excellent long-term stability, with significantly superior aging resistance and high-temperature resistance compared to traditional adhesive bonding methods, greatly improving the structural reliability and service life of the product under complex working conditions.

[0016] 3. The present invention provides a manufacturing process for a low-carbon, high-strength aluminum sandwich panel. By designing the core layer with gradient density and integrating functional units, a single sandwich panel component can simultaneously meet differentiated mechanical load-bearing requirements and specific physical functional requirements, significantly expanding the application field and value space of the product.

[0017] 4. The present invention provides a manufacturing process for a low-carbon, high-strength aluminum sandwich panel. By combining a modular carbon footprint accounting model with a unique digital identifier for each product, it provides transparent and reliable full life-cycle carbon emission data for each product. This not only quantifies and audits the green attributes of the product, but also directly serves the carbon compliance and sustainable development goals of downstream customers, effectively transforming environmental benefits into a competitive market advantage.

[0018] 5. The present invention provides a manufacturing process for a low-carbon, high-strength aluminum sandwich panel. Through core processes such as integrated composite molding, the process is simple, efficient, has a short production cycle, and a high product yield. It overcomes the problems of low efficiency, high cost, and large quality fluctuations that exist in traditional multi-step processes.

[0019] In summary, this invention provides a manufacturing process for low-carbon, high-strength aluminum sandwich panels. Through a complete process from low-carbon material preparation and structural-functional integration to digital environmental value empowerment, it successfully solves the multiple limitations of traditional aluminum sandwich panels in terms of performance, environmental protection, functionality, and reliability. Detailed Implementation

[0020] The following are specific embodiments of the present invention, which further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0021] Example 1: Low-carbon aluminum honeycomb sandwich panel for the lower housing of battery packs in new energy vehicles A manufacturing process for a low-carbon, high-strength aluminum sandwich panel includes the following steps: Raw material preparation and smelting: Category A (60%): Die-casting waste of the same grade ADC12, which is crushed and separated by eddy current separation to remove non-metallic impurities. Category B (25%): Waste motor housings (grade similar to A380), which are devarnished by heat treatment, crushed, and separated by multi-stage cyclone separation and sedimentation to remove ferrous and non-metallic impurities. Category C (15%): Mixed domestic waste aluminum, which is separated by heavy media separation and X-ray fluorescence (XRF) sorting to remove materials containing excessive levels of lead and cadmium.

[0022] Smelting and alloying: The process was carried out in a 30-ton regenerative melting furnace at a temperature controlled at 720±10℃. Al-20Si, Al-50Cu master alloys, and an Al-10La-4Ce mixed rare earth master alloy were added. The mixture was refined for 15 minutes using argon rotary jet blasting (flow rate 15 L / min, rotation speed 250 rpm), followed by settling and slag removal. The final melt composition (wt%) was determined by optical emission spectrometry (OES): Si 10.52, Cu 2.18, Fe 0.92, La 0.098, Ce 0.048, Al balance. Recycled aluminum accounted for 85.3% of the total aluminum input. The hydrogen content of the melt was measured to be 0.18 ml / 100g Al.

[0023] Core layer preform preparation: A portion of the molten metal is cast and rolled into recycled aluminum foil with a thickness of 0.05 ± 0.002 mm and a width of 800 mm. The aluminum foil is then degreased, coated with a modified epoxy resin adhesive, and laminated. Following lamination, it is stretched and formed into a standard aluminum honeycomb core with a regular hexagonal grid, a pore size of 3.0 mm, a foil thickness of 0.05 mm, and a core layer height of 20 mm. The honeycomb core density is approximately 48 kg / m³.

[0024] Integrated Composite Molding: Panel Preparation: The remaining molten material is semi-continuously cast into recycled aluminum alloy strips with a thickness of 1.0 mm and a width of 1000 mm, followed by straightening and length cutting. Surface Treatment: The bonding surface between the panel and the honeycomb core is treated with an automatic sandblasting machine using 80-mesh brown corundum abrasive, achieving a surface roughness Ra of 6.3±0.5 μm. Hot Pressing: A multi-layer hot press is used, with the mold preheated to 480℃. Stacking Sequence: Lower panel → Honeycomb core → Upper panel. Hot Pressing Process: After heating to 500℃, a pressure of 5.0 MPa is applied and held for 30 minutes. Subsequently, the material is slowly cooled to below 300℃ under pressure at a rate ≤10℃ / min. During this process, solid-state diffusion occurs at the interface between the panel and the honeycomb core foil, forming a micro-melt infiltration bond.

[0025] Carbon Footprint Binding: Calculation: Calculated using a self-developed "modular carbon footprint model". Raw Material Side: Category A materials are assigned a value of 0.9 kgCO2e / kg, Category B 1.3, and Category C 2.0. Energy Consumption Side: Measured electricity consumption in smelting, casting, and hot pressing processes is 580 kWh / ton of metal, 120 kWh / ton, and 85 kWh / ton, respectively, multiplied by the South China Power Grid emission factor of 0.581 kgCO2e / kWh. Implicit carbon from auxiliary materials (adhesives, etc.) is included at 0.2 kgCO2e / kg. The calculated carbon footprint for this batch of products is 6.8 kgCO2e / m² (product areal density 8.2 kg / m²). Labeling: A "Product Carbon Footprint Declaration" containing a QR code is generated. Scanning the code will display: a pie chart of raw material composition (60 / 25 / 15), key process parameters (melting 720℃, hot pressing 500℃ / 5MPa / 30min), carbon footprint details (raw materials 5.2, energy consumption 1.4, auxiliary materials 0.2), and the conclusion that emissions are reduced by 70% compared to the traditional primary aluminum-adhesive bonding solution (approximately 22.5 kgCO2e / m²).

[0026] Example 2: Low-carbon gradient aluminum foam sandwich panel for server liquid cooling racks A manufacturing process for a low-carbon, high-strength aluminum sandwich panel includes the following steps: Raw material preparation and smelting: Category A (60%): Die-casting waste of the same grade ADC12, which is crushed and separated by eddy current separation to remove non-metallic impurities. Category B (25%): Waste motor housings (grade similar to A380), which are devarnished by heat treatment, crushed, and separated by multi-stage cyclone separation and sedimentation to remove ferrous and non-metallic impurities. Category C (15%): Mixed domestic waste aluminum, which is separated by heavy media separation and X-ray fluorescence (XRF) sorting to remove materials containing excessive levels of lead and cadmium.

[0027] Smelting and alloying: The process was carried out in a 30-ton regenerative melting furnace at a temperature controlled at 720±10℃. Al-20Si, Al-50Cu master alloys, and an Al-10La-4Ce mixed rare earth master alloy were added. The mixture was refined for 15 minutes using argon rotary jet blasting (flow rate 15 L / min, rotation speed 250 rpm), followed by settling and slag removal. The final melt composition (wt%) was determined by optical emission spectrometry (OES): Si 10.52, Cu 2.18, Fe 0.92, La 0.098, Ce 0.048, Al balance. Recycled aluminum accounted for 85.3% of the total aluminum input. The hydrogen content of the melt was measured to be 0.18 ml / 100g Al.

[0028] Core layer preform preparation: Powder preparation and treatment: Class B recycled aluminum material was atomized with nitrogen to produce spherical aluminum powder with an average particle size of 75 μm. The aluminum powder was mixed with 1.2 wt% TiH2 foaming agent (pre-oxidized at 580℃ / 2h) and 0.5 wt% nano-La2O3 (average particle size 50nm, as a cell stabilizer) in a V-type mixer for 2 hours. Gradient preform forming: Gradient preforms were prepared using a molding-spacer method. 2.0 mm thick steel spacers were placed in the mold at the locations corresponding to the future chip mounting points (4 Φ40mm areas), and 1.0 mm thick spacers were placed in the remaining areas. The mixed powder was then filled in, and the preform was formed under 300 MPa pressure for 1 minute. After demolding, the density of the high-density area (where the spacers are thick) was approximately 1.8 g / cm³, and the density of the low-density area was approximately 1.2 g / cm³. Functional Unit Pre-setting: Several micro-metal capsules (2mm diameter, 0.1mm wall thickness aluminum alloy shell) encapsulated with paraffin (phase change temperature 45-50℃) are pre-embedded in the low-density area of ​​some preforms. The capsule surface is roughened. A serpentine salt core made of NaCl and binder is pre-embedded inside the preform. Flow Channel Pre-setting: A serpentine salt core made of NaCl and binder is pre-embedded inside the preform to form interconnected micro-fluid channels after molding.

[0029] Integrated composite molding: Surface treatment, the upper surface of the preform and the joint surface of the preformed upper panel (1.5mm thick) are roughened by fiber laser with a scanning spacing of 0.1mm and a power of 300W to form a regular pit array with a depth of about 50μm.

[0030] Simultaneous foaming and lamination process: The preform is placed in a steel mold preheated to 550±5℃, with the salt core positioned using refractory fiber. Molten recycled aluminum at 680℃ is rapidly poured into the mold from a pouring cup on one side, submerging the preform. The mold is immediately closed and held at 15 MPa for 120 seconds. During this process, the mold temperature rapidly rises from 550℃ to approximately 620℃ within about 60 seconds, reaching its peak. The TiH2 foaming agent begins to decompose significantly at approximately 580℃, releasing hydrogen gas to foam the aluminum powder matrix. The entire foaming process lasts approximately 90 seconds, occurring simultaneously with melt infiltration and interfacial lamination. After foaming, pressure is maintained and cooling is applied to stabilize and solidify the cell structure under pressure.

[0031] Molten aluminum from the panel penetrates under pressure into the laser-textured structure and near-surface pores on the surface of the preform, forming a metallurgical interface with the foaming core layer. The salt core is encapsulated within the foam. Pre-embedded phase change material capsules, protected by their metal shells, maintain structural integrity during the foaming process, preventing leakage of internal paraffin wax. After molding, they are integrated into the core layer as sealing functional units. Post-processing: The composite preform is immersed in warm water to dissolve and remove the salt core, forming interconnected micro-serpentine cooling channels. The inner walls of the channels are covered with a dense aluminum layer due to the foaming process, ensuring excellent sealing.

[0032] Carbon footprint tracking: Calculations include additional energy consumption for nitrogen atomization powdering, laser texturing, and salt core dissolution. The calculated carbon footprint per unit (400mm×600mm×25mm) is 9.5 kgCO2e. Identification: UHF RFID tags are used, displaying the product ID, gradient density distribution map, functional unit layout (including phase change capsule location), carbon footprint data, and process history. The tags are embedded in the non-load-bearing corners of the product.

[0033] Comparative Example 1: Traditional adhesive-bonded aluminum honeycomb panels using virgin aluminum Raw Material Preparation: Panel: Commercially available virgin 6061-T6 aluminum alloy rolled sheet, thickness 1.0±0.05 mm, chemical composition conforming to GB / T 3190 standard. Wipe with acetone to remove oil stains before use. Core Layer: Standard honeycomb core made of commercially available virgin 3003-H18 aluminum alloy foil, foil thickness 0.05 mm, hexagonal aperture 3.0 mm, height 20.0±0.5 mm, density 48±3 kg / m³. Check the cell structure for integrity before use. Adhesive: Two-component epoxy structural adhesive (model: Araldite® 2015) is selected, with a weight mixing ratio of component A (resin) to component B (curing agent) of 100:35.

[0034] Surface pretreatment: Sand the surfaces to be bonded, including the panel and the honeycomb core, in a uniform direction with 240-grit sandpaper until the surface loses its metallic luster and forms even scratches. Blow away the sanding dust with compressed air, then wipe and degrease twice with a non-woven cloth soaked in industrial acetone, and let it air dry for later use.

[0035] Adhesive preparation and application: Weigh adhesive components A and B according to the specified ratio, and mechanically stir in a plastic cup at 300 rpm for 3 minutes until uniformly mixed and of consistent color. Use a notched scraper (1.0 mm tooth height) to evenly apply the mixed adhesive to the bonding surface of the substrate. Control the wet film thickness of the adhesive layer to 0.15 ± 0.03 mm, with an adhesive application rate of approximately 280 g / m². Accurately place the honeycomb core onto the adhesive-coated panel and gently press to achieve initial contact.

[0036] Lamination and Curing: The top panel is placed on the honeycomb core, forming a sandwich structure of "panel-adhesive-honeycomb-adhesive-panel". The entire assembly is placed between the plates of a hot press, and a slight contact pressure of 0.1 MPa is applied to ensure adhesion. Curing Procedure: Initial curing is performed by heating to 80°C at a rate of 2°C / min and holding at that temperature for 60 minutes; then the heating is turned off, and the assembly is allowed to cool naturally under pressure to below 50°C before removal. Further curing is then carried out at room temperature (23±2°C) under no-pressure conditions for 24 hours to allow the adhesive layer to fully react.

[0037] Post-treatment: After curing, a small amount of excess adhesive may be visible on the edges of the board. Gently remove it with a blade.

[0038] Comparative Example 2: Preparation of foamed aluminum sandwich panels using untreated recycled aluminum Raw Material Acquisition and Processing: A batch of mixed, crushed scrap aluminum, containing aluminum can pieces, broken door and window components, and paint-covered car parts, was randomly purchased from a scrap recycling station without any sorting, cleaning, or paint removal. Only a magnetic separator was used to roughly remove obvious iron pieces before the material was directly fed into the smelting furnace. Smelting and Composition Adjustment: Smelting was carried out in a conventional reverberatory furnace at temperatures exceeding 750°C to melt the paint-covered scrap, producing a large amount of black smoke. The melt surface had a lot of slag, mainly composed of alumina, salts, and residual paint dust. After simple slag removal, samples were taken for spectral analysis, showing an Fe content of 1.85%, Si 8.2%, Cu 1.5%, and 0.15% Pb detected. Only Al-Si and Al-Cu master alloys were added to adjust Si and Cu to approximately 11% and 2%, respectively, without adding any rare earth elements. The refining process involved simply purging nitrogen for a few minutes, resulting in a high hydrogen content in the melt. Core Powder and Preform Preparation: The above-mentioned poor-quality melt was atomized into powder, resulting in an irregular powder with severe surface oxidation. This recycled aluminum powder was mixed with 1.5 wt% TiH2 foaming agent (without pre-oxidation treatment) in a drum for 1 hour. No cell stabilizers (such as La2O3) were added. The mixed powder was unidirectionally pressed at 200 MPa into a homogeneous cylindrical preform with a density of approximately 1.5 g / cm³. The preform had low strength and was prone to powder shedding at the edges. Composite Process: The preform was placed in a mold, and recycled aluminum melt from the same batch (temperature approximately 700℃) was poured in. The mold was closed and pressurized to 10 MPa.

[0039] Because the raw materials used in this comparative example were not subject to classification and control, their composition was complex and contained a large amount of organic matter and impurities, resulting in an increase of approximately 20% in energy consumption during the smelting process. Furthermore, melt refining was difficult, and burn-off was severe. A rough calculation shows that its unit product carbon footprint is approximately 15.2 kgCO2e / m² (based on a 50% yield rate, with a large amount of waste requiring remelting), far exceeding that of Examples 1 and 2. Simultaneously, due to substandard product performance, its "effective" carbon footprint (i.e., the carbon emissions corresponding to providing satisfactory performance) is extremely high, lacking any environmental value.

[0040] Comparative Example 3: Independent preparation of aluminum foam core boards: A relatively mature melt foaming method was employed, using virgin A356 molten aluminum with 1.0% Ca added as a thickener, followed by 1.2% TiH2 for foaming. The mixture was poured into an open mold, foamed in a furnace, and cooled to obtain a 20mm thick aluminum foam board with a density of 0.6 g / cm³. The top and bottom surfaces of this aluminum foam board were then milled using a CNC milling machine to obtain a smooth and flat surface, with a machining allowance of approximately 1mm.

[0041] Panel preparation: Using a high-performance recycled aluminum alloy with the same composition as in Embodiment 1 of the present invention, a 1.5mm thick sheet is cast and cut into the same size as the foamed aluminum sheet.

[0042] Welding: Align and stack the bottom panel, the milled aluminum foam board, and the top panel in sequence.

[0043] An automatic tungsten inert gas (TIG) welding machine was used, employing Φ2.0mm ER4043 welding wire. Fillet welds were performed along the perimeter of the sandwich structure to weld the upper and lower panels to the central aluminum foam board. Welding process phenomena: The high temperature of the electric arc instantly melted the walls of the aluminum foam pores. The molten aluminum flowed and accumulated under the influence of gravity, arc force, and surface tension, causing the foam structure, approximately 3-5mm deep, to completely collapse and densify within the heat-affected zone (HAZ), forming a solid but coarse-grained aluminum strip, rather than a foam structure. Welding parameters: current 90A, voltage 12V, welding speed 8 cm / min, argon gas shielding flow rate 15 L / min. In this comparative example, the aluminum foam core layer and the panels needed to be prepared separately, adding two melting and processing steps. In particular, the CNC milling process was time-consuming and had a high material removal rate (approximately 30%), and the TIG welding process had high energy consumption, resulting in an overall process energy consumption far exceeding that of the integrated molding solution. Calculations show that the product's carbon footprint is approximately 13.5 kgCO2e / m², and due to the high thermal resistance at the welding interface, it has a high risk of functional failure, resulting in poor overall environmental benefits. Comparative Example 4: A manufacturing process for a low-carbon, high-strength aluminum sandwich panel, comprising the following steps: Raw material preparation and smelting: Category A (60%): Die-casting waste of the same grade ADC12, which is crushed and separated by eddy current separation to remove non-metallic impurities. Category B (25%): Waste motor housings (grade similar to A380), which are devarnished by heat treatment, crushed, and separated by multi-stage cyclone separation and sedimentation to remove ferrous and non-metallic impurities. Category C (15%): Mixed domestic waste aluminum, which is separated by heavy media separation and X-ray fluorescence (XRF) sorting to remove materials containing excessive levels of lead and cadmium.

[0044] Smelting and alloying: The process was carried out in a 30-ton regenerative melting furnace at a temperature controlled at 720±10℃. Al-20Si, Al-50Cu master alloys, and an Al-10La-4Ce mixed rare earth master alloy were added. The mixture was refined for 15 minutes using argon rotary jet blasting (flow rate 15 L / min, rotation speed 250 rpm), followed by settling and slag removal. The final melt composition (wt%) was determined by optical emission spectrometry (OES): Si 10.52, Cu 2.18, Fe 0.92, La 0.098, Ce 0.048, Al balance. Recycled aluminum accounted for 85.3% of the total aluminum input. The hydrogen content of the melt was measured to be 0.18 ml / 100g Al.

[0045] Core layer preform preparation: A portion of the molten metal is cast and rolled into recycled aluminum foil with a thickness of 0.05 ± 0.002 mm and a width of 800 mm. The aluminum foil is then degreased, coated with a modified epoxy resin adhesive, and laminated. Following lamination, it is stretched and formed into a standard aluminum honeycomb core with a regular hexagonal grid, a pore size of 3.0 mm, a foil thickness of 0.05 mm, and a core layer height of 20 mm. The honeycomb core density is approximately 48 kg / m³.

[0046] Integrated Composite Molding: Panel Preparation: The remaining molten material is semi-continuously cast into recycled aluminum alloy strips with a thickness of 1.0 mm and a width of 1000 mm, followed by straightening and length cutting. Surface Treatment: The bonding surface between the panel and the honeycomb core is treated with an automatic sandblasting machine using 80-mesh brown corundum abrasive, achieving a surface roughness Ra of 6.3±0.5 μm. Hot Pressing: A multi-layer hot press is used, with the mold preheated to 480℃. Stacking Sequence: Lower panel → Honeycomb core → Upper panel. Hot Pressing Process: After heating to 500℃, a pressure of 5.0 MPa is applied and held for 30 minutes. Subsequently, the material is slowly cooled to below 300℃ under pressure at a rate ≤10℃ / min. During this process, solid-state diffusion occurs at the interface between the panel and the honeycomb core foil, forming a micro-melt infiltration bond.

[0047] This comparative product is made from 85.3% recycled aluminum and has the same microstructure, interfacial bonding strength, and macroscopic mechanical properties as Example 1. Its flexural strength is also 152 MPa, and its interfacial peel strength is 85 N·mm / mm. However, because it lacks carbon footprint binding, this product is only circulated as a high-performance recycled aluminum sandwich panel. Its life-cycle carbon emission data (post-calculated, also approximately 6.8 kgCO2e / m²) cannot be reliably and traceably transmitted to downstream customers. In scenarios requiring an Environmental Product Declaration (EPD) or for customers' own carbon accounting, this comparative product will lack a competitive advantage, as its green attributes cannot be quantified and verified, thus affecting its market value and compliance.

[0048] Table 1 Comparison of material composition and process parameters between the examples and comparative examples

[0049] As shown in Table 1 above, the aluminum honeycomb sandwich panel prepared in Example 1 has a higher bending strength (152 MPa) and peel strength (85 N·mm / mm) than the adhesive panel using virgin aluminum in Comparative Example 1 (145 MPa, 68 N·mm / mm). This directly proves that the performance of the recycled aluminum matrix is ​​fundamentally improved through the material and process treatment of the present invention. The metallurgical bonding interface formed by the "simultaneous foaming" process in Example 2 has a shear strength (45 MPa) that is 2-3 times that of traditional epoxy structural adhesive (15-20 MPa). The collapse of the heat-affected zone and the high interfacial thermal resistance in Comparative Example 3 highlight the unique advantages of integrated micro-melting bonding in ensuring core integrity and achieving high interfacial heat transfer efficiency. Long-term durability guarantee: The adhesive board of Comparative Example 1 suffered severe performance degradation after humid heat aging, while the interface based on metallurgical bonding does not have the problem of organic material aging, and the fire resistance rating reaches UL94 V-0, ensuring the structural safety and reliability of the product throughout its entire life cycle.

[0050] Table 2 Comparison of structural and performance test data between the example and comparative products

[0051] As shown in Table 2, the product of Example 1, which uses ≥85% recycled aluminum raw materials, exhibits significantly superior flexural strength and interfacial peel strength compared to the control product using virgin aluminum. This performance improvement demonstrates that, through its unique rare earth purification and graded control system, this invention not only solves the inherent problem of fluctuations in recycled aluminum composition but also surpasses the basic mechanical properties of high-end virgin alloys. The shear strength of this metallurgical interface is 2-3 times that of top-tier structural adhesives, completely avoiding the risk of a 38% strength drop in adhesives after humid heat aging. Simultaneously, its fire resistance rating reaches the highest V-0 level. This signifies an improvement in product lifespan and environmental adaptability. A deep integration of structure and function is achieved through an integrated process. In Example 2, a mechanical property gradient and embedded micro-cooling channels were successfully constructed internally. Its overall thermal conductivity is 2.6 times that of traditional welding processes, and the temperature rise is reduced by over 100% under simulated heat dissipation conditions.

[0052] Table 3 Comparison of carbon footprint accounting and environmental benefits in the examples and comparative examples

[0053] The results in Table 3 show that the carbon footprint is reduced by orders of magnitude: the core carbon reduction stems from replacing primary aluminum with recycled aluminum. The carbon footprint of the product in Example 1 is 6.8 kgCO2e / m², while that of the traditional primary aluminum product in Comparative Example 1 is as high as 22.5 kgCO2e / m², resulting in an absolute emission reduction of 15.7 kgCO2e / m², and a relative emission reduction of approximately 70%. Specifically, the carbon emission intensity in the raw material stage alone decreased from 16.5 kgCO2e / kg for primary aluminum to approximately 1.15 kgCO2e / kg for the recycled aluminum system, a reduction of over 93%. Through a "digital passport" equipped with a QR code / RFID tag, this invention transforms the abstract concept of "green" into an auditable data chain containing specific raw material proportions, process energy consumption, and accounting methods. This contrasts sharply with Comparative Example 4, enabling downstream customers to directly use reliable data to complete their own carbon accounting and ESG reports, transforming environmental attributes into tangible supply chain competitive advantages and commercial value.

[0054] Table 4 Qualitative comparison of process efficiency and economy in the examples and comparative examples

[0055] The results in Tables 2 and 4 show that the integrated process of simultaneous foaming and lamination combines multiple steps into one, shortening the production cycle and avoiding the interface damage and inefficiency problems found in the process of foaming followed by bonding, as in Comparative Example 3. Combined with raw material grading and online control, a high yield (>95%) is ensured using fluctuating recycled aluminum as raw material.

[0056] Example 2 successfully fabricated a sandwich panel with gradient density and built-in microchannels. Tests showed that this functional design improved heat dissipation efficiency. This marks the product's evolution from a passive structural component to an active thermal management functional component, meeting the stringent requirements of high-end applications for lightweight, load-bearing, and heat dissipation integration.

[0057] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A manufacturing process for a low-carbon, high-strength aluminum sandwich panel, characterized in that, Includes the following steps: S1: Raw material preparation and smelting: Prepare recycled aluminum raw materials, smelt and add alloying elements and rare earth elements to obtain recycled aluminum alloy, which is used to prepare the panel of sandwich panel. S2: Core layer preform preparation, using recycled aluminum as the main raw material to prepare a porous metal core layer preform; S3: Integrated composite molding, the core layer preform and the panel material are placed in the molding environment, and under the combined action of heat and force, the panel and the core layer are bonded together through interface metallurgy or micro-melting bonding to form an integrated composite blank. S4: Carbon footprint binding, calculate and generate carbon footprint data for the entire life cycle of the sandwich panel, and uniquely bind the data to the product entity.

2. The manufacturing process of a low-carbon, high-strength aluminum sandwich panel as described in claim 1, characterized in that, In step S1, the recycled aluminum alloy melt contains, by weight percentage: 8.0-12.0% Si, 1.5-3.0% Cu, 0.03-0.25% rare earth elements, with the balance being Al. The proportion of the recycled aluminum raw material to the total aluminum input is not less than 70 wt%.

3. The manufacturing process of a low-carbon, high-strength aluminum sandwich panel as described in claim 2, characterized in that, The rare earth elements are a combination of lanthanum (La) and cerium (Ce), and the recycled aluminum raw materials are subject to a graded and classified management process based on their source, composition and cleanliness.

4. The manufacturing process of a low-carbon, high-strength aluminum sandwich panel as described in claim 3, characterized in that, In step S2, the porous metal core preform is a foamed aluminum preform or an aluminum honeycomb core. When preparing the foamed aluminum preform, the raw materials contain a foaming agent and a cell stabilizer, and the cell stabilizer contains rare earth oxides.

5. The manufacturing process of a low-carbon, high-strength aluminum sandwich panel as described in claim 2, characterized in that, The integrated composite process described in step S3 involves simultaneous foaming and composite formation. The core layer preform containing the foaming agent is placed in a mold, and the melt for the panel is poured in. Under pressure, the core layer foaming and interface composite are completed simultaneously.

6. The manufacturing process of a low-carbon, high-strength aluminum sandwich panel as described in claim 5, characterized in that, In step S3, the bonding surfaces of the panel materials are roughened before lamination to enhance the interfacial bonding strength. The roughening pretreatment includes at least one of laser roughening, micro-arc oxidation, or chemical etching.

7. The manufacturing process of a low-carbon, high-strength aluminum sandwich panel as described in claim 2, characterized in that, In step S4, the carbon footprint data is accessed by scanning the QR code attached to the product or reading the RFID tag. The data includes at least: the proportion of recycled aluminum raw materials, the energy consumption of key processes, and the carbon emission intensity per unit product.

8. A low-carbon aluminum-based sandwich panel prepared by the preparation process described in any one of claims 1 to 7.

9. The low-carbon aluminum-based sandwich panel according to claim 8, characterized in that, The core layer of the sandwich panel has a non-uniform density distribution, forming a mechanical property gradient structure; the core layer integrates functional units, which are sealed phase change material capsules or interconnected micro fluid channels.

10. The application of the low-carbon aluminum-based sandwich panel as described in claim 9 in lightweight structural components of transportation vehicles, housings and protective components of power battery packs, or heat dissipation and load-bearing components of electronic devices.

Images