A high corrosion resistant and heat treatable foamed aluminum produced from recycled aluminum and a method of making the same

Abstract

This application provides a highly corrosion-resistant and heat-treatable aluminum foam produced from recycled aluminum, and its preparation method. The aluminum foam is prepared from a fully recycled aluminum raw material system, wherein the aluminum foam matrix, by weight percentage, consists of Si 9%-13%, Mg 0.4%-0.8%, Cu 0.05%-0.1%, Fe 0.1%-0.3%, Mn 0.05%-0.1%, Zn 0.05%-0.10%, other unavoidable impurities ≤0.2%, and the balance being Al. Combined with a secondary refining process, a high-viscosity foam stabilization process, and a solution-free low-temperature aging process, the aluminum foam utilizes the strengthening effect of Mg₂Si phase dispersion precipitation and the continuous metallic conductive network effect to simultaneously possess corrosion resistance similar to that of primary aluminum and the characteristics of low-temperature aging strengthening without solution quenching. The resulting aluminum foam has a bulk density of 0.4 g / cm³-0.8 g / cm³, an average pore size of ≤3 mm, and a closed-cell rate of ≥90%. It can be widely used in new energy vehicles, 5G communications, rail transit, aerospace and military electromagnetic protection fields. It has the advantages of being green and environmentally friendly, low cost, controllable process, stable performance, and easy to promote and implement.

Description

Technical Field

[0001] This application belongs to the field of porous metal materials technology, specifically relating to a foamed aluminum produced from recycled aluminum with high corrosion resistance and heat-treatable strengthening, and its preparation method. Background Technology

[0002] In existing technologies, aluminum foam is a lightweight structural-functional integrated material with numerous pores distributed within an aluminum matrix. It combines the mechanical properties of metallic materials with the functional characteristics of porous materials, exhibiting excellent properties such as low density, high specific strength, energy absorption and shock absorption, heat insulation and sound insulation, and electromagnetic shielding. It has been widely used in fields such as protective structures for battery packs in new energy vehicles, energy-absorbing buffer devices for rail transit vehicles, shielding shells for 5G communication equipment, structural components for aerospace vehicles, and military electromagnetic protection equipment. With the deepening of global energy conservation, emission reduction, and green manufacturing concepts, the use of recycled aluminum to produce aluminum foam has become an inevitable trend in the industry. This not only reduces production costs but also effectively reduces bauxite resource consumption and environmental pollution.

[0003] However, current foamed aluminum produced using recycled aluminum and its preparation technology suffer from numerous performance shortcomings and technical bottlenecks that are difficult to balance, severely restricting its large-scale promotion and application. Specifically, existing technologies mainly have the following defects:

[0004] First, aluminum foam made from pure aluminum or non-heat-treated aluminum alloys has low strength and poor load-bearing capacity. The as-cast compressive strength of pure aluminum matrix aluminum foam is usually only 4MPa-8MPa, which cannot meet the structural load-bearing capacity requirements of new energy vehicles, rail transit and other fields; while aluminum foam made from non-heat-treated aluminum alloys has limited improvement in mechanical properties and it is difficult to achieve a balance between high strength and low density.

[0005] Secondly, heat-treatable aluminum foam requires high-temperature solution treatment followed by quenching to achieve high strength, but this process has serious drawbacks. The high-temperature solution treatment temperature is typically above 500℃, which causes softening, collapse, and cracking of the aluminum foam pore walls, resulting in uneven pore size, structural integrity loss, and a significant reduction in yield. Simultaneously, the enormous thermal stress generated during quenching further exacerbates pore wall cracking, severely impacting the mechanical properties and service life of the aluminum foam. Furthermore, the high-temperature solution treatment followed by quenching is energy-intensive and has a long production cycle, significantly increasing production costs.

[0006] Third, existing technologies cannot simultaneously achieve the requirements of low density, small pore size, and high strength in aluminum foam. To obtain high strength, it is usually necessary to increase the density of aluminum foam, which leads to the loss of its lightweight advantage; to obtain small pore size, it is often necessary to increase the amount of foaming agent or increase the stirring speed, but this can easily cause bubble coalescence and uneven pore size.

[0007] Furthermore, the production of aluminum foam using recycled aluminum faces the significant problem of poor corrosion resistance. Recycled aluminum typically contains high levels of impurity elements such as Cu and Fe. These elements form a cathode phase in the aluminum matrix, creating a galvanic cell and triggering severe electrochemical corrosion. Since aluminum foam has a large specific surface area, the exposed pores after cutting easily trap acids, alkalis, water, and electrolytes, further accelerating the corrosion process. This leads to a sharp decline in the mechanical properties of the aluminum foam and a significantly shortened service life.

[0008] Therefore, in order to comprehensively improve the mechanical properties, corrosion resistance, and production economy of recycled aluminum foam, and to achieve a synergistic balance between low density, small pore size, and high strength, and to solve the technical problems of low strength, easy collapse after heat treatment, poor shielding performance, and insufficient corrosion resistance of traditional aluminum foam, it is currently urgent to make systematic improvements to the composition design, preparation process, and strengthening methods of recycled aluminum foam, so as to meet the urgent needs of high-performance aluminum foam in fields such as new energy vehicles, 5G communication, rail transportation, aerospace, and military industry. Summary of the Invention

[0009] In order to address the technical problems in the prior art, such as low strength and poor load-bearing capacity of recycled aluminum foam, easy collapse and cracking of pore walls and low yield due to high-temperature solution treatment and quenching of heat-treatable aluminum foam, difficulty in simultaneously achieving the requirements of low density, small pore size and high strength, and poor corrosion resistance due to high impurity content of recycled aluminum, this application proposes a high corrosion-resistant and heat-treatable aluminum foam produced from recycled aluminum and its preparation method.

[0010] This application adopts the following scheme: a foamed aluminum with high corrosion resistance and heat-treatable strengthening produced from recycled aluminum, which is composed of the following components by weight percentage: Si 9%-13%, Mg 0.4%-0.8%, Cu 0.05%-0.1%, Fe 0.1%-0.3%, Mn 0.05%-0.1%, Zn 0.05%-0.10%, other unavoidable impurities ≤0.2%, and the balance being Al;

[0011] The aluminum foam has a bulk density of 0.4 g / cm³-0.8 g / cm³, an average pore size of 1 mm-3 mm, and a closed-cell rate of 90%-95%.

[0012] In some feasible embodiments, the aluminum foam is composed of the following components by weight percentage: Si 11.5%-12.5%, Mg 0.55%-0.65%, Cu 0.06%-0.1%, Fe 0.2%-0.3%, Mn 0.06%-0.1%, Zn 0.06%-0.1%, other impurities ≤0.2%, and the balance being Al.

[0013] In some feasible embodiments, the pore size distribution of the aluminum foam is 0.5 mm-3.0 mm, and the pore size variation coefficient is ≤20%.

[0014] To address the technical problems raised in this application, this application also provides a method for preparing highly corrosion-resistant and heat-treatable aluminum foam produced from recycled aluminum, comprising the following steps:

[0015] Step 101. Preparation of recycled aluminum alloy liquid: Use recycled aluminum raw materials to prepare the liquid according to the preset alloy ratio, melt it, adjust the composition according to the preset target alloy ratio, and then refine it a second time to obtain the aluminum alloy liquid.

[0016] Step 102. High viscosity foam stabilization: Add 0.9wt%-1.6wt% of metallic Ca by total mass of aluminum alloy liquid to the aluminum alloy liquid obtained in step 101, stir for 5min-10min, and control the melt viscosity at 2.0Pa·s-3.5Pa·s to obtain high viscosity melt;

[0017] Step 103. Small pore size and high closed-cell foaming: Add pre-oxidized TiH2 foaming agent to the high viscosity melt obtained in step 102. The amount of TiH2 foaming agent added is 1.4wt%-2.2wt% of the total mass of the high viscosity melt. Shear and stir at a high speed of 1000r / min-1800r / min for 30s-50s. Then pour it out and inject it into a mold preheated to 460℃-520℃. Keep it at 610℃-630℃ for 10min-20min to foam. Cool it to room temperature with the furnace to obtain the aluminum foam billet.

[0018] Step 104. Cut the aluminum foam blank obtained in step 103 into a square shape to obtain aluminum foam sheets. Then lay the aluminum foam sheets flat or on a shelf, leaving a hot air ventilation gap of ≥10mm.

[0019] Step 105. Solution-free low-temperature artificial aging: Heat the foamed aluminum sheet after loading into the furnace to 170℃-180℃ at a heating rate of ≤48℃ / h, hold for 8h-12h, and cool to room temperature with the furnace to obtain the finished foamed aluminum product.

[0020] In some feasible embodiments, in step 101, the recycled aluminum raw materials include: recycled automotive aluminum wheel hubs, aluminum alloy door and window materials, waste aluminum ladders, waste TV antennas, waste magnesium sheets, and photovoltaic panel cutting scraps.

[0021] In some feasible embodiments, step 101 includes the following steps: first, put the aluminum wheel hub of the car into the melting furnace and heat it to 720℃-750℃ to melt it. Then, add the photovoltaic panel cutting scraps, aluminum alloy door and window materials, waste aluminum ladders and waste TV antennas in sequence. After they are completely melted, press the waste magnesium sheet completely into the aluminum melt until the waste magnesium sheet melts.

[0022] In some feasible embodiments, the secondary refining in step 101 includes the following steps: at 720℃-740℃, firstly, a refining agent is added at 0.3% of the aluminum liquid volume, and flux refining is carried out using a graphite rotor refining device. After the reaction is completed and no large bubbles float to the surface, argon gas is introduced for gas refining. After refining, the slag is removed, and a K mold is taken for testing. The refining is carried out until the K value is ≤1 / 20.

[0023] In some feasible embodiments, step 103, the pre-oxidation treatment of the TiH2 foaming agent includes the following steps: pre-oxidizing the TiH2 foaming agent at 530℃-550℃ for 30min-60min in an air atmosphere.

[0024] In some feasible embodiments, in step 105, the heat preservation time is determined according to the thickness of the aluminum foam sheet: 4h-10h for thickness ≤10mm, and 10h-12h for thickness >10mm; the temperature uniformity at any point in the furnace during the aging process is ≤±3℃.

[0025] Compared with the prior art, this application has the following beneficial effects:

[0026] This application provides a foamed aluminum with high corrosion resistance and heat-treatable strengthening properties produced from recycled aluminum, and a method for its preparation. This application uses recycled aluminum raw materials such as recycled automotive aluminum wheel hubs, aluminum alloy door and window materials, and waste aluminum ladders to produce foamed aluminum, realizing the recycling of aluminum resources, significantly reducing raw material costs and energy consumption, and conforming to the concepts of green manufacturing and sustainable development.

[0027] This application effectively inhibits electrochemical corrosion by precisely controlling the content of impurity elements such as Cu, Fe, Mn, and Zn. At the same time, the high closed-cell structure reduces the hiding space of corrosive media, enabling the corrosion resistance of recycled aluminum foam to reach a level similar to that of foam produced from primary aluminum, thus significantly extending the product's service life.

[0028] This application uses the AlSi12Mg0.6 alloy system, which does not require high-temperature solution treatment and quenching. The Mg2Si phase can be dispersedly precipitated by artificial aging at a low temperature of 170℃-180℃, which increases the compressive strength by ≥30%. It completely avoids the problems of pore wall collapse and cracking caused by high-temperature solution treatment, with a yield of ≥96%, while reducing energy consumption by more than 40% and significantly shortening the production cycle.

[0029] This application achieves pore structure control with a closed-cell rate of ≥90% and an average pore diameter of ≤3mm through the synergistic effect of a high-viscosity stabilizing foam system and a high-speed shear foaming process, forming a continuous and complete metal conductive network, which effectively improves the electromagnetic shielding performance of aluminum foam.

[0030] This application solves the problem that traditional aluminum foam cannot simultaneously achieve low density (0.4g / cm³-0.8g / cm³), small pore size (≤3mm), and high strength (compressive strength increased by ≥30% after aging). The resulting aluminum foam has multiple properties such as lightweight, high strength, energy absorption, heat insulation, and flame retardancy, and can be widely used in new energy vehicles, 5G communication, rail transportation, aerospace, and military electromagnetic protection. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the aluminum foam prepared in Example 2 of this application.

[0032] Figure 2 This is a process flow diagram of the preparation of aluminum foam in Examples 1-2 of this application. Detailed Implementation

[0033] Combination Figures 1 to 2 Examples 1 and 2, and Comparative Example 1, further illustrate the technical solution proposed in this application. Specifically, this application adopts the following technical solution: a highly corrosion-resistant and heat-treatable aluminum foam produced from recycled aluminum, the matrix chemical composition by weight percentage being: Si 11.5%-12.5%, Mg... The aluminum foam contains 0.55%-0.65% Cu≤0.10%, Fe≤0.30%, Mn≤0.10%, Zn≤0.10%, and other impurities ≤0.2%, with the balance being Al. The bulk density of the aluminum foam is 0.4g / cm³-0.8g / cm³, the average pore size is 0.5mm-3.0mm, the closed-cell rate is ≥90%, and the pore size variation coefficient is ≤20%. The aluminum foam is not subjected to solution treatment or quenching treatment. It is artificially aged at a low temperature of 170℃-180℃ for 4h-12h to precipitate a dispersed Mg2Si strengthening phase in the pore walls. After aging, the compressive strength is increased by ≥30% compared to the as-cast state. When the density is 0.7g / cm³, the compressive strength after aging is 14.5MPa-19.5MPa.

[0034] Example 1

[0035] This embodiment prepares a high-shielding aluminum foam with a density of 0.5 g / cm³. The specific steps are as follows:

[0036] 【1】Preparation of recycled aluminum alloy liquid:

[0037] Prepare 300 kg of molten aluminum according to the chemical composition of recycled aluminum raw materials shown in Table 1. Weigh out 150 kg of recycled aluminum car wheel hubs (A356), 126 kg of dismantled aluminum alloy door and window materials (6063), 23.5 kg of photovoltaic panel cutting scraps (silicon content 99.9999%), and 0.55 kg of sorted crushed magnesium sheets (AZ91D) (magnesium content 90%). Put the aluminum car wheel hubs into a resistance melting furnace, heat to 730℃ to melt, and then add... Photovoltaic panel cutting scraps and aluminum alloy door and window materials are added and, after complete melting, broken magnesium flakes are slowly pressed into the bottom of the molten aluminum using a special graphite pressure spoon, isolating them from open flames to prevent magnesium from burning. After stirring evenly, samples are taken for testing, and the composition is adjusted according to the test results to achieve a final alloy composition of Al-11.5Si-0.55Mg (wt%), where Cu≤0.08%, Fe≤0.25%, Mn≤0.07%, Zn≤0.06%, and the total amount of other impurities≤0.15%.

[0038] Secondary refining was carried out at 730℃: First, sodium-free refining agent was added at 0.3% of the aluminum liquid volume, and the refining was carried out for 8 minutes at a speed of 600 r / min using a graphite rotor refining equipment (GBF). After the reaction was completed and no large bubbles floated to the surface, argon gas with a purity of ≥99.99% was introduced for gas refining for 10 minutes at a flow rate of 15 L / min. After refining, the scum was removed, and the K mold was tested. The K value was 1 / 25, which met the requirements.

[0039] [2] High viscosity foam stabilizer:

[0040] Add 1.1 wt% of metallic Ca particles to the refined aluminum alloy liquid, and stir with a graphite stirrer at a speed of 200 r / min for 7 min, controlling the melt viscosity to be around 2.8 Pa·s.

[0041] [3] Small pore size high closed-cell foaming:

[0042] 1.9wt% of TiH2 foaming agent, which has been pre-oxidized at 540℃ for 45min, is added to the melt. The melt is then immediately sheared and stirred at a high speed of 1500r / min for 40s. The mixture is then quickly poured into a steel mold preheated to 500℃ and foamed at 620℃ for 15min. The mixture is then cooled to room temperature in the furnace to obtain the aluminum foam billet.

[0043] [4] Cutting and loading into the furnace:

[0044] The aluminum foam blank is squared, and the irregular parts on the sides and top surface are removed. It is then cut into 10mm thick aluminum foam sheets using a vertical saw. The aluminum foam sheets are then placed on the aging furnace rack with a 15mm gap between them for hot air ventilation to prevent them from being squeezed and stacked.

[0045] 【5】Solution-free low-temperature artificial aging:

[0046] The aging furnace is heated to 170°C at a heating rate of 40°C / hour, held at that temperature for 6 hours, and then cooled to room temperature with the furnace to obtain the finished aluminum foam.

[0047] Example 2

[0048] This embodiment prepares an ultra-high shielding aluminum foam with a density of 0.7 g / cm³. The specific steps are as follows:

[0049] 【1】Preparation of recycled aluminum alloy liquid:

[0050] Prepare 300 kg of molten aluminum according to the chemical composition of recycled aluminum raw materials shown in Table 1. Weigh out 132 kg of recycled aluminum car wheel hubs (A356), 141 kg of waste TV antennas (6005), 26.3 kg of photovoltaic panel cutting scraps (silicon content 99.9999%), and 0.7 kg of sorted crushed magnesium sheets (AZ91D) (magnesium content 90%). Put the aluminum car wheel hubs into a resistance melting furnace and heat to 740℃ to melt. Then add the photovoltaic panel cutting scraps and waste TV antennas in sequence. After they are completely melted, use a special graphite pressure spoon to slowly press the crushed magnesium sheets into the bottom of the molten aluminum, isolating it from open flames to prevent magnesium from burning. After stirring evenly, take a sample for testing. Adjust the composition according to the test results so that the final alloy composition is Al-12.2Si-0.62Mg (wt%), where Cu≤0.07%, Fe≤0.22%, Mn≤0.06%, Zn≤0.05%, and the total amount of other impurities≤0.12%.

[0051] Secondary refining was carried out at 735℃: First, sodium-free refining agent was added at 0.3% of the aluminum liquid volume, and the refining was carried out for 7 minutes at a speed of 600 r / min using a graphite rotor refining equipment (GBF). After the reaction was completed and no large bubbles floated to the surface, argon gas with a purity of ≥99.99% was introduced for gas refining for 12 minutes at a flow rate of 18 L / min. After refining, the scum was removed, and the K-mold was tested. The K value was 1 / 30, which met the requirements.

[0052] [2] High viscosity foam stabilizer:

[0053] Add 1.3wt% metallic Ca particles to the refined aluminum alloy liquid, and stir with a graphite stirrer at a speed of 220r / min for 8min, controlling the melt viscosity to be around 3.2Pa·s.

[0054] [3] Small pore size high closed-cell foaming:

[0055] 1.6 wt% of TiH2 foaming agent, which has been pre-oxidized at 535℃ for 50 min, is added to the melt. The melt is then immediately sheared and stirred at a high speed of 1200 r / min for 45 s. The melt is then quickly poured into a steel mold preheated to 490℃ and foamed at 615℃ for 12 min. The melt is then cooled to room temperature with the furnace to obtain the aluminum foam billet.

[0056] [4] Cutting and loading into the furnace:

[0057] The aluminum foam blank is squared, and the irregular parts on the sides and top surface are removed. It is then cut into 15mm thick aluminum foam sheets using a vertical saw. The aluminum foam sheets are then placed on the aging furnace rack with a 12mm hot air ventilation gap between the sheets to avoid compression and stacking.

[0058] 【5】Solution-free low-temperature artificial aging:

[0059] The aging furnace is heated to 170°C at a heating rate of 35°C / hour, held at that temperature for 11 hours, and then cooled to room temperature with the furnace to obtain the finished aluminum foam.

[0060] Comparative Example 1

[0061] This comparative example uses traditional pure aluminum foam, and the specific preparation steps are as follows:

[0062] Primary aluminum with a purity of ≥99.7% was used as raw material, melted at 700℃, and 2wt% metallic Ca was added for thickening, and stirred for 10min. 1.45wt% pretreated TiH2 foaming agent was added, and stirred at 1600r / min for 3min. The mixture was then kept at 695℃ for 4.5min for foaming, and cooled to room temperature in the furnace. The mixture was then cut into plates of the same size as in the example, without aging treatment.

[0063] Table 1. Alloy composition of recycled aluminum raw materials used in Examples 1 to 2 (wt%)

[0064] Raw material name Aluminum alloy grades Si Fe Cu Mn Zn Mg Ti Other impurities margin Recycling car aluminum wheels A356 6.5-7.5 0.20-0.30 ≤0.20 ≤0.10 ≤0.10 0.25-0.45 ≤0.20 ≤0.15 Al Disassembly of aluminum alloy door and window materials 6063 0.20-0.60 0.10-0.30 ≤0.10 0.05-0.20 ≤0.10 0.45-0.90 ≤0.10 ≤0.15 Al Recycling scrap aluminum ladders / TV antennas 6005 0.60-0.90 0.10-0.35 ≤0.10 0.05-0.20 ≤0.10 0.45-0.80 ≤0.10 ≤0.15 Al Sorting and breaking magnesium flakes AZ91D ≤0.10 ≤0.05 ≤0.05 ≤0.05 1.0 90 - ≤0.30 Al Photovoltaic panel cutting scraps - ≥99.9999 ≤0.0001 ≤0.0001 ≤0.0001 ≤0.0001 - - ≤0.0001 Si

[0065] The performance of the aluminum foam samples prepared in Example 1, Example 2, and Comparative Example 1 was tested. The test items and standards are as follows:

[0066] Density: Determined by the water displacement method, referring to GB / T 20082.1-2006 "Determination of density and porosity of porous metallic materials - Part 1: Impregnation method";

[0067] Pore ​​size and closed-porosity: determined by image analysis method, referring to GB / T 21650.1-2008 "Determination of pore size distribution and porosity of solid materials by mercury porosimetry and gas adsorption method - Part 1: Mercury porosimetry";

[0068] Compressive strength: determined using a universal testing machine, in accordance with GB / T 20082.2-2006 "Determination of compressive properties of porous metallic materials";

[0069] Corrosion resistance: The corrosion resistance was determined by a neutral salt spray test, referring to GB / T 10125-2012 "Artificial Atmosphere Corrosion Test - Salt Spray Test", with a test duration of 1000 hours, and the corrosion weight loss rate was calculated.

[0070] The test results are shown in Table 2.

[0071] project Example 1 Example 2 Comparative Example 1 Density (g / cm³) 0.50 0.70 0.41 Average aperture (mm) 2.8 2.2 4.0 Closed-pore ratio (%) 92 93 85 As-cast compressive strength (MPa) 7.4 11.6 4.0 Compressive strength (MPa) after artificial aging 10.2 15.5 Non-time-limited reinforcement Compressive strength improvement rate (%) 37.8 33.6 - Weight loss rate (mg / cm²) after 1000 hours of neutral salt spray corrosion 0.12 0.11 0.10 Finished product yield (%) 97.2 96.8 88.5 Energy consumption per unit (kWh / t) 1250 1320 2280

[0072] As shown in Table 2, the compressive strength of the aluminum foam prepared in Examples 1 and 2 reached 10.2 MPa and 15.5 MPa respectively after low-temperature artificial aging, which is 37.8% and 33.6% higher than that in the as-cast state, respectively. This is much higher than the 4.0 MPa of the pure aluminum foam in Comparative Example 1, and no high-temperature solution treatment and quenching treatment are required, which effectively avoids the problem of pore wall collapse and cracking.

[0073] The closed-cell rates of the aluminum foams prepared in Examples 1 and 2 reached 92% and 93%, respectively, forming a continuous and complete metallic conductive network, which can effectively meet the requirements of 5G communication, military electromagnetic protection and other fields.

[0074] In Examples 1 and 2, by strictly controlling the content of impurity elements such as Cu and Fe, the weight loss rates of neutral salt spray corrosion in Examples 1 and 2 after 1000 hours were 0.12 mg / cm² and 0.11 mg / cm², respectively, which are comparable to 0.10 mg / cm² of primary aluminum foam in Comparative Example 1. This proves that the recycled aluminum foam of the present invention has corrosion resistance similar to that of primary aluminum foam.

[0075] Furthermore, Examples 1 and 2 use fully recycled aluminum raw materials and do not require high-temperature solution treatment and quenching processes. The yield is ≥96%, and the unit energy consumption is only 1250kWh / t-1320kWh / t, which is more than 45% lower than the traditional process in Comparative Example 1, showing significant economic advantages.

[0076] In summary, this application provides a highly corrosion-resistant and heat-treatable aluminum foam produced from recycled aluminum, and its preparation method. Through the synergistic design of a specific AlSi12Mg0.6 alloy matrix, strict control of impurity elements, a high-viscosity foam stabilizing system, and a solution-free low-temperature aging process, the technical challenges of low strength, easy collapse during heat treatment, insufficient corrosion resistance, and difficulty in simultaneously achieving the three core indicators of low density, small pore size, and high strength in traditional aluminum foam are successfully solved. The resulting aluminum foam has excellent performance, low production cost, and is environmentally friendly. It can be widely used in new energy vehicles, 5G communications, rail transportation, aerospace, and military electromagnetic protection, and has significant application value.

[0077] The embodiments provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A type of highly corrosion-resistant and heat-treatable aluminum foam produced from recycled aluminum, characterized in that, By weight percentage, it consists of the following components: Si 9%-13%, Mg 0.4%-0.8%, Cu 0.05%-0.1%, Fe 0.1%-0.3%, Mn 0.05%-0.1%, Zn 0.05%-0.10%, other unavoidable impurities ≤0.2%, and the balance being Al; The aluminum foam has a bulk density of 0.4 g / cm³-0.8 g / cm³, an average pore size of 1 mm-3 mm, and a closed-cell rate of 90%-95%.

2. The highly corrosion-resistant and heat-treatable aluminum foam produced from recycled aluminum according to claim 1, characterized in that, The aluminum foam, by weight percentage, is composed of the following components: Si 11.5%-12.5%, Mg 0.55%-0.65%, Cu 0.06%-0.1%, Fe 0.2%-0.3%, Mn 0.06%-0.1%, Zn 0.06%-0.1%, other impurities ≤0.2%, and the balance being Al.

3. The highly corrosion-resistant and heat-treatable aluminum foam produced from recycled aluminum according to claim 1, characterized in that, The pore size distribution of the aluminum foam is 0.5mm-3.0mm.

4. A method for preparing highly corrosion-resistant and heat-treatable aluminum foam produced from recycled aluminum according to any one of claims 1 to 3, characterized in that, Includes the following steps: Step 101. Preparation of recycled aluminum alloy liquid: Use recycled aluminum raw materials to prepare the liquid according to the preset alloy ratio, melt it, adjust the composition according to the preset target alloy ratio, and then refine it a second time to obtain the aluminum alloy liquid. Step 102. High viscosity foam stabilization: Add 0.9wt%-1.6wt% of metallic Ca by total mass of aluminum alloy liquid to the aluminum alloy liquid obtained in step 101, stir for 5min-10min, and control the melt viscosity at 2.0Pa·s-3.5Pa·s to obtain high viscosity melt; Step 103. Small pore size and high closed-cell foaming: Add pre-oxidized TiH2 foaming agent to the high viscosity melt obtained in step 102. The amount of TiH2 foaming agent added is 1.4wt%-2.2wt% of the total mass of the high viscosity melt. Shear and stir at a high speed of 1000r / min-1800r / min for 30s-50s. Then pour it out and inject it into a mold preheated to 460℃-520℃. Keep it at 610℃-630℃ for 10min-20min to foam. Cool it to room temperature with the furnace to obtain the aluminum foam billet. Step 104. Cut the aluminum foam blank obtained in step 103 into a square shape to obtain aluminum foam sheets. Then lay the aluminum foam sheets flat or on a shelf, leaving a hot air ventilation gap of ≥10mm. Step 105. Solution-free low-temperature artificial aging: Heat the foamed aluminum sheet after loading into the furnace to 170℃-180℃ at a heating rate of ≤48℃ / h, hold for 8h-12h, and cool to room temperature with the furnace to obtain the finished foamed aluminum product.

5. A method for preparing highly corrosion-resistant and heat-treatable aluminum foam produced from recycled aluminum according to claim 4, characterized in that, In step 101, the recycled aluminum raw materials include: recycled automotive aluminum wheel hubs, aluminum alloy door and window materials, waste aluminum ladders, waste TV antennas, waste magnesium sheets, and photovoltaic panel cutting scraps.

6. A method for preparing highly corrosion-resistant and heat-treatable aluminum foam produced from recycled aluminum according to claim 5, characterized in that, Step 101 includes the following steps: First, put the aluminum car wheel hub into the melting furnace and heat it to 720℃-750℃ to melt it. Then, add the photovoltaic panel cutting scraps, aluminum alloy door and window materials, waste aluminum ladders and waste TV antennas in sequence. After they are completely melted, press the waste magnesium sheet completely into the aluminum melt until the waste magnesium sheet melts.

7. A method for preparing highly corrosion-resistant and heat-treatable aluminum foam produced from recycled aluminum according to claim 5, characterized in that, In step 101, the secondary refining includes the following steps: at 720℃-740℃, firstly, a refining agent is added at 0.3% of the aluminum liquid volume, and flux refining is carried out using a graphite rotor refining device. After the reaction is completed and no large bubbles float to the surface, argon gas is introduced for gas refining. After refining, the slag is removed, and a K mold is taken for testing. The refining is carried out until the K value is ≤1 / 20.

8. A method for preparing highly corrosion-resistant and heat-treatable aluminum foam produced from recycled aluminum according to claim 4, characterized in that, In step 103, the pre-oxidation treatment of the TiH2 foaming agent includes the following steps: pre-oxidizing the TiH2 foaming agent at 530℃-550℃ for 30min-60min in an air atmosphere.

9. A method for preparing highly corrosion-resistant and heat-treatable aluminum foam produced from recycled aluminum according to claim 4, characterized in that, In step 105, the heat preservation time is determined according to the thickness of the aluminum foam sheet: 4h-10h for thickness ≤10mm, and 10h-12h for thickness >10mm; the temperature uniformity at any point in the furnace during the aging process is ≤±3℃.

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