High-strength heat-insulating aluminum profile and preparation process thereof

Abstract

The application belongs to the technical field of metal materials, and particularly relates to a high-strength heat-insulating aluminum profile and a preparation process thereof. The preparation process comprises the following steps: preparation of a high-strength aluminum-lithium alloy profile; construction of an aluminum oxide array layer on the surface of the aluminum-lithium alloy; and heat-insulating treatment of the aluminum-lithium alloy profile with the aluminum oxide array layer. The application lays a foundation for the preparation of the high-strength aluminum-lithium alloy profile by optimizing the aluminum alloy formula. On this basis, the preparation process of the aluminum-lithium alloy profile is regulated. Through the cooling mode of water cooling + air cooling in the smelting stage, the component segregation is effectively inhibited, and the as-cast grains are refined. The subsequent two-stage homogenization completely dissolves the non-equilibrium phase and eliminates the dendritic segregation. Then, through the composite deformation process of three-dimensional cyclic forging + warm rolling + cold rolling of XYZ axes, the grains are driven to be ultra-fined, and a strong and thin structure is formed. Finally, the two-stage solid solution realizes efficient solid solution and water quenching locking of the strengthening phase, so that the alloy has high compressive performance under the premise of lightweight.

Description

Technical Field

[0001] This invention belongs to the field of metal materials technology, specifically relating to a high-strength heat-insulating aluminum profile and its preparation process. Background Technology

[0002] Aluminum-lithium alloys, due to their excellent specific strength, specific stiffness, and good corrosion resistance, have become one of the key structural materials for achieving lightweighting in modern aerospace, and are widely used in components such as aircraft fuselage frames, skins, bulkheads, and rocket propellant tanks. By adding lithium to traditional aluminum alloys, the material density is significantly reduced while maintaining good mechanical properties, meeting the urgent needs of aircraft for weight reduction and improved fuel efficiency, making them an important material choice for next-generation civil airliners and military aircraft.

[0003] However, when aluminum-lithium alloys are applied to critical components such as aircraft wing skin, which need to withstand high loads and face harsh aerodynamic and thermal environments, a significant challenge lies in their insufficient thermal insulation performance. Existing technologies typically employ a method of attaching a layer of polymer or ceramic fiber insulation felt to the outside of the aluminum-lithium alloy skin structure using adhesives to achieve thermal insulation. While this composite structure solves the thermal insulation problem to some extent, it introduces new drawbacks: the adhesive layer and the additional insulation layer significantly increase the parasitic mass of the overall structure, partially offsetting the core advantage of aluminum-lithium alloys in terms of lightweight design. Furthermore, the adhesive interface may experience delamination failure during long-term service due to environmental aging, vibration, or thermal stress, affecting structural integrity and service life. In addition, the installation of the insulation felt also increases the complexity of the manufacturing process.

[0004] Therefore, developing an integrated aluminum-lithium alloy material that combines high strength and lightweight intrinsic properties with excellent thermal insulation function, and avoiding the weight increase and reliability problems caused by secondary bonding, is crucial for improving the overall performance of next-generation aircraft. Summary of the Invention

[0005] To address the aforementioned technical deficiencies, this invention presents a manufacturing process for high-strength heat-insulating aluminum profiles, resulting in high-strength heat-insulating aluminum profiles with high heat resistance stability, high peel strength, and high water resistance.

[0006] A high-strength thermally insulated aluminum profile comprises a high-strength aluminum-lithium alloy profile, an alumina array layer, and melamine microcapsules-calcium silicate nano-aerogel. The high-strength aluminum-lithium alloy profile has the following composition by mass percentage: Cu: 1.35-2%, Li: 1.9-2.3%, Zn: 5.2-6%, Mg: 0.8-1%, Pr: 0.25-0.4%, Sc: 0.15-0.25%, Zr: 0.08-0.12%, with the balance being Al and unavoidable impurities.

[0007] The alumina array layer is attached to the surface of the high-strength aluminum-lithium alloy profile, and the melamine microcapsule-calcium silicate nano-aerogel is filled inside the alumina array layer.

[0008] A manufacturing process for a high-strength, heat-insulating aluminum profile includes the following steps:

[0009] S1: Preparation of high-strength aluminum-lithium alloy profiles;

[0010] S2: Construction of an alumina array layer on the surface of an aluminum-lithium alloy;

[0011] S3: Thermal insulation treatment of aluminum-lithium alloy profiles with alumina array layer.

[0012] Furthermore, the preparation of the high-strength aluminum-lithium alloy profile in step S1 specifically includes the following steps:

[0013] S1.1: The elements are present in the following mass percentages: 1.35-2% Cu, 1.9-2.3% Li, 5.2-6% Zn, 0.8-1% Mg, 0.25-0.4% Pr, 0.15-0.25% Sc, 0.08-0.12% Zr, and the balance Al. Pure Al ingots are added to a melting furnace and melted at 750-800℃. The temperature is then lowered to 720-740℃, and argon gas is introduced as a protective gas. Pure Cu ingots are then added sequentially... Pure Li ingots, pure Zn ingots, pure Mg ingots, as well as Al-15wt%Pr master alloys, Al-13wt%Zr master alloys, and Al-10wt%Sc master alloys, are thoroughly stirred and degassed after complete melting. After standing for 5-10 minutes, they are poured into molds and first water-cooled to 400-420℃ at a cooling rate of 10-15℃ / s, and then air-cooled to room temperature at a cooling rate of 2-3℃ / s to obtain aluminum-lithium alloy ingots.

[0014] S1.2: Place the aluminum-lithium alloy ingot into an atmosphere sintering furnace, first heat it to 480-485℃ at a heating rate of 10-12℃ / min and hold it for 8-10 hours, then heat it to 520-525℃ at a heating rate of 5-6℃ / min and hold it for 10-12 hours, and finally cool it down to room temperature at a cooling rate of 20-25℃ / min. Then, saw off the head and tail and mill the surface to obtain a homogenized aluminum-lithium alloy ingot.

[0015] S1.3: Remove the oxide scale from the surface of the homogenized aluminum-lithium alloy ingot, then heat it to 450-480℃, and upset it sequentially along the X / Y / Z axes in a forging machine. The deformation amount per pass is 55-60%, and the cycle is repeated 3 times. Then transfer it to a warm rolling mill, control the speed ratio of the upper roll speed to the lower roll speed to be 1:(1.1-1.2), the rolling temperature to be 330-350℃, the reduction per pass to be 10-20%, and the final rolling thickness to be 5-7mm. Then cold roll it with a reduction of 5-10% per pass to a final rolling thickness of 2-2.5mm to obtain aluminum-lithium alloy sheets.

[0016] S1.4: The aluminum-lithium alloy sheet is dissolved at 460-480℃ for 0.5-1h, then dissolved at 500-510℃ for 1-1.2h, and then water-quenched to room temperature to obtain a high-strength aluminum-lithium alloy profile.

[0017] Furthermore, the construction of the aluminum oxide array layer on the surface of the aluminum-lithium alloy in step S2 specifically includes the following steps:

[0018] S2.1: Place the high-strength aluminum-lithium alloy profile in deionized water containing 5wt% sodium dodecylbenzenesulfonate and treat it with an ultrasonic cleaner at 35-40kHz for 10-12 minutes. After taking it out, immerse it in anhydrous ethanol and repeat the ultrasonic cleaning for 8-10 minutes. Rinse it with deionized water 3-4 times and then place it in a vacuum drying oven at 40-45℃ for 1-1.5 hours to obtain a clean aluminum-lithium alloy profile.

[0019] S2.2: Place aluminum acetate trihydrate in anhydrous ethanol, and then stir for 30-40 min in a water bath at 60-70℃ to obtain an aluminum acetate ethanol solution with a concentration of 10-15 mmol / L. Immerse the clean aluminum-lithium alloy profile in the aluminum acetate ethanol solution and pull it up at a uniform speed 3-4 times. Then place it in a muffle furnace and heat it to 180-200℃ at a heating rate of 5-10℃ / min and hold it for 1-1.5 h. After natural cooling, pull it up at a uniform speed 3-4 times in the aluminum acetate ethanol solution and hold it in a muffle furnace at 180-200℃ for 1-1.5 h. Repeat the pulling-holding operation 2-3 times to obtain an Al2O3 seed layer aluminum-lithium alloy profile.

[0020] S2.3: Prepare an aluminum nitrate solution with a concentration of 50-60 mmol / L and place it in a container. Then add an equal volume of hexamethylenetetramine solution with a concentration of 50-60 mmol / L. Stir magnetically at 80-100 rpm for 18-20 hours at room temperature to obtain an array growth solution. Vertically immerse the Al2O3 seed layer aluminum-lithium alloy profile into the array growth solution and then transfer it to an oven at 90-95℃ for 8-10 hours. After cooling, wash it 2-3 times with anhydrous ethanol and deionized water in sequence, and dry it at 60-65℃ to constant weight to form an alumina array layer, thus obtaining an alumina array layer aluminum-lithium alloy profile.

[0021] Furthermore, the heat insulation treatment of the aluminum-lithium alloy profile with the alumina array layer in step S3 specifically includes the following steps:

[0022] S3.1: Melamine, formaldehyde, urea and deionized water are added to a container in a mass ratio of 1:(3.8-3.85):(0.9-0.95):(3.85-4) and mixed evenly. Triethanolamine is added to adjust the pH to 8.5-9. Then, the mixture is stirred at 80-85℃ and 450-500rpm for 30-35min to obtain melamine ester prepolymer.

[0023] S3.2: Styrene-maleic anhydride, sodium hydroxide, and deionized water are mixed in a mass ratio of 1:(0.3-0.4):(8.5-9) and placed in a container. The mixture is heated at 80-85℃ for 1-1.5h to obtain a styrene-maleic anhydride solution. The styrene-maleic anhydride solution, melamine prepolymer, and n-octadecane are mixed in a mass ratio of 1:(4.4-4.5):(0.8-1) and placed in a high-speed emulsifier. The mixture is emulsified at 6000-6500rpm for 25-30min. Acetic acid is then added dropwise to adjust the pH. The mixture is heated in a water bath at 450-500rpm and 50-55℃ for 30-35min. The temperature is then increased to 70-75℃ and heated in a water bath for 2.5-3h. The precipitate is collected by filtration, rinsed with deionized water, and dried to obtain melamine microcapsules.

[0024] S3.3: Add polyvinyl alcohol to distilled water and stir at 85-90℃ until the polyvinyl alcohol is fully dissolved. Let it stand and cool to room temperature to prepare a PVA solution with a mass concentration of 8-10%. Add 1 mol / L calcium nitrate solution and melamine microcapsules to the PVA solution and mix well. Then slowly add 1 mol / L sodium silicate solution to obtain a melamine microcapsule-calcium silicate nano suspension.

[0025] S3.4: Place the aluminum-lithium alloy profile with alumina array layer in a vacuum filtration tank, evacuate to 800-1000 Pa and maintain for 30-35 min, then adjust to normal pressure, add melamine microcapsule-calcium silicate nano suspension to immerse the aluminum-lithium alloy profile with alumina array layer, continue evacuating to 400-500 Pa and maintain for 1.5-2 h, take it out and dry at 45-50℃ to constant weight, forming melamine microcapsule-calcium silicate nano aerogel in the alumina array layer, to obtain a high-strength heat-insulating aluminum profile.

[0026] Furthermore, the gas used for degassing and slag removal in step S1.1 is hexachloroethane.

[0027] Furthermore, the uniform lifting speed in step S2.2 is 6-8 cm / min.

[0028] Furthermore, after adjusting the pH by adding acetic acid in step S3.2, the pH of the styrene-maleic anhydride solution, melamine prepolymer, and n-octadecane mixed solution is 5.5-6.

[0029] Further, in step S3.3, the mass ratio of calcium nitrate solution: melamine microcapsules: sodium silicate solution: PVA solution is 1: (0.03-0.04): (1-1.2): (2-3).

[0030] The beneficial effects are as follows: 1. This invention optimizes the aluminum alloy formula and controls the component ratio. Based on Cu, Li, and Zn, rare earth elements Pr, Sc, and Zr are introduced for synergistic strengthening, laying the foundation for the preparation of high-strength aluminum-lithium alloy profiles. On this basis, the preparation process of aluminum-lithium alloy profiles is controlled. By using water cooling + air cooling in the smelting stage, component segregation is effectively suppressed and the as-cast grains are refined. The subsequent two-stage homogenization completely dissolves the non-equilibrium phase and eliminates dendritic segregation, laying a uniform microstructure foundation for subsequent deformation. Then, through the composite deformation process of three-dimensional cyclic forging + warm rolling + cold rolling along the XYZ axis, the grains are driven to become ultra-fine and form a strong fine structure. Finally, the two-stage solid solution achieves efficient solid solution and water quenching locking of the strengthening phase, so that the alloy has high compressibility under the premise of lightweighting, and its comprehensive performance is better than that of the traditional Al-Li alloy system.

[0031] 2. This invention involves immersing a clean aluminum-lithium alloy profile in an aluminum acetate ethanol solution for lifting, followed by heat treatment in a muffle furnace. This process is repeated several times to obtain an Al2O3 seed layer aluminum-lithium alloy profile. The profile is then placed in an array growth solution for heat treatment, forming a regular alumina array layer on the surface. This creates a closed gas chamber inside, effectively suppressing gas thermal convection. Furthermore, its regular layered structure can efficiently absorb and scatter thermal radiation photons, enhancing heat insulation capabilities. This ensures lightweight design while giving the aluminum profile excellent heat insulation performance.

[0032] 3. This invention prepares a melamine microcapsule-calcium silicate nano-suspension, and then places an aluminum-lithium alloy profile with an alumina array layer into the melamine microcapsule-calcium silicate nano-suspension for vacuum impregnation. This allows the regular pore structure of the alumina array layer to be filled with melamine microcapsules and calcium silicate nanoparticles. During drying, the melamine microcapsules and calcium silicate nanoparticles form an aerogel network structure connected to the inner wall of the pore structure, which can further enhance the thermal insulation capacity of the aluminum profile. While ensuring lightweight design, the aluminum profile also possesses excellent thermal insulation capabilities. Attached Figure Description

[0033] Figure 1 This is a SEM image of the surface of the high-strength heat-insulating aluminum profile prepared in Example 1 of this application. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] A high-strength thermally insulated aluminum profile comprises a high-strength aluminum-lithium alloy profile, an alumina array layer, and melamine microcapsules-calcium silicate nano-aerogel. The high-strength aluminum-lithium alloy profile has the following composition by mass percentage: Cu: 1.35%, Li: 1.9%, Zn: 5.2%, Mg: 0.8%, Pr: 0.25%, Sc: 0.15%, Zr: 0.08%, with the balance being Al and unavoidable impurities.

[0037] The alumina array layer is attached to the surface of the high-strength aluminum-lithium alloy profile, and the melamine microcapsule-calcium silicate nano-aerogel is filled inside the alumina array layer.

[0038] A manufacturing process for a high-strength, heat-insulating aluminum profile includes the following steps:

[0039] S1: Preparation of high-strength aluminum-lithium alloy profiles

[0040] S1.1: The elements are in the following mass percentages: 1.35% Cu, 1.9% Li, 5.2% Zn, 0.8% Mg, 0.25% Pr, 0.15% Sc, 0.08% Zr and balance Al. Pure Al ingots are added to a melting furnace and melted at 750℃. The temperature is then lowered to 720℃ and argon protective gas is introduced. Pure Cu ingots, pure Li ingots, pure Zn ingots, pure Mg ingots, as well as Al-15wt%Pr master alloy, Al-13wt%Zr master alloy and Al-10wt%Sc master alloy are added in sequence. After complete melting, the mixture is stirred thoroughly and degassed with hexachloroethane to remove slag. The mixture is allowed to stand for 5 minutes and then poured into a mold. It is first water-cooled to 400℃ at a cooling rate of 15℃ / s, and then air-cooled to room temperature at a cooling rate of 2℃ / s to obtain aluminum-lithium alloy ingots.

[0041] S1.2: The aluminum-lithium alloy ingot is placed in an atmosphere sintering furnace, heated to 480℃ at a heating rate of 10℃ / min and held for 8 hours, then heated to 520℃ at a heating rate of 5℃ / min and held for 10 hours, and finally cooled to room temperature at a cooling rate of 20℃ / min. The ends are then sawed and the surface is milled to obtain a homogenized aluminum-lithium alloy ingot.

[0042] S1.3: Remove the oxide scale from the surface of the homogenized aluminum-lithium alloy ingot, then heat it to 450°C, and upset it sequentially along the X / Y / Z axes in a forging machine. The deformation amount in each pass is 55%, and the cycle is repeated 3 times. Then, transfer it to a warm rolling mill, control the speed ratio of the upper roll speed to the lower roll speed to be 1:1.1, the rolling temperature to be 330°C, the reduction per pass to be 10%, and the final rolling thickness to be 5mm. Then, cold roll it with a reduction of 5% per pass to a final rolling thickness of 2mm to obtain an aluminum-lithium alloy sheet.

[0043] S1.4: The aluminum-lithium alloy sheet is dissolved at 460℃ for 0.5h, then dissolved at 500℃ for 1h, and then quenched in water to room temperature to obtain a high-strength aluminum-lithium alloy profile.

[0044] S2: Construction of an alumina array layer on the surface of an aluminum-lithium alloy

[0045] S2.1: The high-strength aluminum-lithium alloy profile is placed in deionized water containing 5wt% sodium dodecylbenzenesulfonate and treated with an ultrasonic cleaner at 35kHz for 10 minutes. After being removed, it is immersed in anhydrous ethanol and ultrasonically cleaned repeatedly for 8 minutes. After rinsing with deionized water 3 times, it is placed in a vacuum drying oven at 40℃ for 1 hour to obtain a clean aluminum-lithium alloy profile.

[0046] S2.2: Aluminum acetate trihydrate was placed in anhydrous ethanol and stirred for 30 min in a water bath at 60°C to obtain an aluminum acetate ethanol solution with a concentration of 10 mmol / L. The clean aluminum-lithium alloy profile was immersed in the aluminum acetate ethanol solution and pulled three times at a uniform speed. Then it was placed in a muffle furnace and heated to 180°C at a heating rate of 5°C / min and held for 1 h. After natural cooling, it was pulled three times at a uniform speed of 6 cm / min in the aluminum acetate ethanol solution and held in a muffle furnace at 180°C for 1 h. The pulling-holding operation was repeated twice to obtain an Al2O3 seed layer aluminum-lithium alloy profile.

[0047] S2.3: Prepare an aluminum nitrate solution with a concentration of 50 mmol / L and place it in a container. Then add an equal volume of hexamethylenetetramine solution with a concentration of 50 mmol / L. Stir magnetically at 80 rpm for 18 h at room temperature to obtain an array growth solution. Vertically immerse the Al2O3 seed layer aluminum-lithium alloy profile into the array growth solution and then transfer it to a 90℃ oven for 8 h. After cooling, wash it twice with anhydrous ethanol and deionized water, and dry it at 60℃ to constant weight to form an alumina array layer, thus obtaining an alumina array layer aluminum-lithium alloy profile.

[0048] S3: Thermal insulation treatment of aluminum-lithium alloy profiles with alumina array layer

[0049] S3.1: Melamine, formaldehyde, urea and deionized water are added to a container in a mass ratio of 1:3.8:0.9:3.85 and mixed evenly. Triethanolamine is added to adjust the pH to 8.5. Then, the mixture is stirred at 80℃ and 450rpm for 30min to obtain melamine prepolymer.

[0050] S3.2: Styrene-maleic anhydride, sodium hydroxide, and deionized water were mixed in a mass ratio of 1:0.3:8.5 and placed in a container. The mixture was heated at 80°C for 1 hour to obtain a styrene-maleic anhydride solution. The styrene-maleic anhydride solution, melamine prepolymer, and n-octadecane were mixed in a mass ratio of 1:4.4:0.8 and placed in a high-speed emulsifier. The mixture was emulsified at 6000 rpm for 25 minutes. Acetic acid was then added dropwise to adjust the pH to 5.5. The mixture was heated in a water bath at 450 rpm and 50°C for 30 minutes. The temperature was then increased to 70°C and heated in a water bath for 2.5 hours. The precipitate was collected by filtration, rinsed with deionized water, and dried to obtain melamine microcapsules.

[0051] S3.3: Add polyvinyl alcohol to distilled water and stir at 85°C until the polyvinyl alcohol is fully dissolved. Let it stand and cool to room temperature to prepare a PVA solution with a mass concentration of 8%. Add 1 mol / L calcium nitrate solution and melamine microcapsules to the PVA solution and mix well. Then slowly add 1 mol / L sodium silicate solution. The mass ratio of calcium nitrate solution: melamine microcapsules: sodium silicate solution: PVA solution is 1:0.03:1:2 to obtain a melamine microcapsule-calcium silicate nano suspension.

[0052] S3.4: Place the aluminum-lithium alloy profile with alumina array layer in a vacuum filtration tank, evacuate to 800 Pa and maintain for 30 min, then adjust to normal pressure, add melamine microcapsule-calcium silicate nano suspension to immerse the aluminum-lithium alloy profile with alumina array layer, continue evacuating to 400 Pa and maintain for 1.5 h, take it out and dry at 45 °C to constant weight, forming melamine microcapsule-calcium silicate nano aerogel in the alumina array layer, to obtain a high-strength heat-insulating aluminum profile.

[0053] Example 2

[0054] A high-strength thermally insulated aluminum profile comprises a high-strength aluminum-lithium alloy profile, an alumina array layer, and melamine microcapsules-calcium silicate nano-aerogel. The high-strength aluminum-lithium alloy profile has the following composition by mass percentage: Cu: 1.8%, Li: 2.1%, Zn: 5.6%, Mg: 0.9%, Pr: 0.35%, Sc: 0.2%, Zr: 0.1%, with the balance being Al and unavoidable impurities.

[0055] The alumina array layer is attached to the surface of the high-strength aluminum-lithium alloy profile, and the melamine microcapsule-calcium silicate nano-aerogel is filled inside the alumina array layer.

[0056] A manufacturing process for a high-strength, heat-insulating aluminum profile includes the following steps:

[0057] S1: Preparation of high-strength aluminum-lithium alloy profiles

[0058] S1.1: The elements are in the following mass percentages: 1.8% Cu, 2.1% Li, 5.6% Zn, 0.9% Mg, 0.35% Pr, 0.2% Sc, 0.1% Zr and balance Al. Pure Al ingots are added to a melting furnace and melted at 775℃. The temperature is then lowered to 730℃ and argon gas is introduced for protection. Pure Cu ingots, pure Li ingots, pure Zn ingots, pure Mg ingots, Al-15wt%Pr master alloy, Al-13wt%Zr master alloy and Al-10wt%Sc master alloy are added in sequence. After complete melting, the mixture is stirred thoroughly and degassed with hexachloroethane to remove slag. The mixture is allowed to stand for 7 minutes and then poured into a mold. It is first water-cooled to 410℃ at a cooling rate of 13℃ / s, and then air-cooled to room temperature at a cooling rate of 3℃ / s to obtain aluminum-lithium alloy ingots.

[0059] S1.2: The aluminum-lithium alloy ingot is placed in an atmosphere sintering furnace, heated to 483℃ at a heating rate of 11℃ / min and held for 9 hours, then heated to 523℃ at a heating rate of 5.5℃ / min and held for 11 hours, and finally cooled to room temperature at a cooling rate of 22.5℃ / min. The ingot is then sawn at the head and tail and milled to obtain a homogenized aluminum-lithium alloy ingot.

[0060] S1.3: Remove the oxide scale from the surface of the homogenized aluminum-lithium alloy ingot, then heat it to 465℃, and upset it sequentially along the X / Y / Z axes in a forging machine. The deformation amount per pass is 58%, and the cycle is repeated 3 times. Then, transfer it to a warm rolling mill, control the speed ratio of the upper roll speed to the lower roll speed to be 1:1.2, the rolling temperature to be 340℃, the reduction per pass to be 15%, and the final rolling thickness to be 6mm. Then, cold roll it with a reduction of 8% per pass to obtain a final rolling thickness of 2.3mm to obtain an aluminum-lithium alloy sheet.

[0061] S1.4: The aluminum-lithium alloy sheet is dissolved at 470℃ for 0.8h, then dissolved at 505℃ for 1.1h, and then water-quenched to room temperature to obtain a high-strength aluminum-lithium alloy profile.

[0062] S2: Construction of an alumina array layer on the surface of an aluminum-lithium alloy

[0063] S2.1: The high-strength aluminum-lithium alloy profile was placed in deionized water containing 5wt% sodium dodecylbenzenesulfonate and treated with an ultrasonic cleaner at 38kHz for 11 minutes. After being removed, it was immersed in anhydrous ethanol and ultrasonically cleaned repeatedly for 9 minutes. After rinsing with deionized water 4 times, it was placed in a vacuum drying oven at 43℃ for 1.2 hours to obtain a clean aluminum-lithium alloy profile.

[0064] S2.2: Aluminum acetate trihydrate was placed in anhydrous ethanol and stirred for 35 min in a water bath at 60°C to obtain an aluminum acetate ethanol solution with a concentration of 13 mmol / L. The clean aluminum-lithium alloy profile was immersed in the aluminum acetate ethanol solution and pulled up 4 times at a uniform speed. Then it was placed in a muffle furnace and heated to 190°C at a heating rate of 8°C / min and held for 1.2 h. After natural cooling, it was pulled up 3 times at a uniform speed of 7 cm / min in the aluminum acetate ethanol solution and held in a muffle furnace at 190°C for 1.3 h. The pulling-holding operation was repeated 3 times to obtain an Al2O3 seed layer aluminum-lithium alloy profile.

[0065] S2.3: Prepare an aluminum nitrate solution with a concentration of 55 mmol / L and place it in a container. Then add an equal volume of hexamethylenetetramine solution with a concentration of 55 mmol / L. Stir magnetically at 90 rpm for 19 h at room temperature to obtain an array growth solution. Vertically immerse the Al2O3 seed layer aluminum-lithium alloy profile into the array growth solution and then transfer it to a 93℃ oven for 9 h. After cooling, wash it three times with anhydrous ethanol and deionized water in sequence, and dry it at 62℃ to constant weight to form an alumina array layer, thus obtaining an alumina array layer aluminum-lithium alloy profile.

[0066] S3: Thermal insulation treatment of aluminum-lithium alloy profiles with alumina array layer

[0067] S3.1: Melamine, formaldehyde, urea and deionized water are added to a container in a mass ratio of 1:3.82:0.92:3.95 and mixed evenly. Triethanolamine is added to adjust the pH to 8.8. Then the mixture is stirred at 83℃ and 475rpm for 32min to obtain melamine prepolymer.

[0068] S3.2: Styrene-maleic anhydride, sodium hydroxide, and deionized water were mixed in a mass ratio of 1:0.35:8.8 and placed in a container. The mixture was heated at 83°C for 1.2 h to obtain a styrene-maleic anhydride solution. The styrene-maleic anhydride solution, melamine prepolymer, and n-octadecane were mixed in a mass ratio of 1:4.45:0.9 and placed in a high-speed emulsifier. The mixture was emulsified at 6250 rpm for 27 min. Acetic acid was then added dropwise to adjust the pH to 5.8. The mixture was heated in a water bath at 475 rpm and 53°C for 32 min. The temperature was then increased to 72°C and heated in a water bath for 2.8 h. The precipitate was collected by filtration, rinsed with deionized water, and dried to obtain melamine microcapsules.

[0069] S3.3: Polyvinyl alcohol was added to distilled water and stirred at 87°C until the polyvinyl alcohol was fully dissolved. The mixture was allowed to stand and cool to room temperature to prepare a 9% PVA solution. 1 mol / L calcium nitrate solution and melamine microcapsules were added to the PVA solution and mixed evenly. Then, 1 mol / L sodium silicate solution was slowly added dropwise. The mass ratio of calcium nitrate solution:melamine microcapsules:sodium silicate solution:PVA solution was 1:0.035:1.1:2.5 to obtain a melamine microcapsule-calcium silicate nanosuspension.

[0070] S3.4: Place the aluminum-lithium alloy profile with alumina array layer in a vacuum filtration tank, evacuate to 900 Pa and maintain for 32 min, then adjust to normal pressure, add melamine microcapsule-calcium silicate nano suspension to immerse the aluminum-lithium alloy profile with alumina array layer, continue evacuating to 450 Pa and maintain for 1.8 h, take it out and dry at 48℃ to constant weight, forming melamine microcapsule-calcium silicate nano aerogel in the alumina array layer, to obtain a high-strength heat-insulating aluminum profile.

[0071] Example 3

[0072] A high-strength thermally insulated aluminum profile comprises a high-strength aluminum-lithium alloy profile, an alumina array layer, and melamine microcapsules-calcium silicate nano-aerogel. The high-strength aluminum-lithium alloy profile has the following composition by mass percentage: Cu: 2%, Li: 2.3%, Zn: 6%, Mg: 1%, Pr: 0.4%, Sc: 0.25%, Zr: 0.12%, with the balance being Al and unavoidable impurities.

[0073] The alumina array layer is attached to the surface of the high-strength aluminum-lithium alloy profile, and the melamine microcapsule-calcium silicate nano-aerogel is filled inside the alumina array layer.

[0074] A manufacturing process for a high-strength, heat-insulating aluminum profile includes the following steps:

[0075] S1: Preparation of high-strength aluminum-lithium alloy profiles

[0076] S1.1: The mass percentages of the elements are: 2% Cu, 2.3% Li, 6% Zn, 1% Mg, 0.4% Pr, 0.25% Sc, 0.12% Zr and the balance Al. Pure Al ingots are added to a melting furnace and melted at 800℃. The temperature is then lowered to 740℃ and argon protective gas is introduced. Pure Cu ingots, pure Li ingots, pure Zn ingots, pure Mg ingots, Al-15wt%Pr master alloy, Al-13wt%Zr master alloy and Al-10wt%Sc master alloy are added in sequence. After complete melting, the mixture is stirred thoroughly and degassed with hexachloroethane to remove slag. The mixture is allowed to stand for 10 minutes and then poured into a mold. It is first water-cooled to 420℃ at a cooling rate of 10℃ / s, and then air-cooled to room temperature at a cooling rate of 3℃ / s to obtain an aluminum-lithium alloy ingot.

[0077] S1.2: The aluminum-lithium alloy ingot is placed in an atmosphere sintering furnace. First, the temperature is raised to 485℃ at a heating rate of 12℃ / min and held for 10h. Then, the temperature is raised to 525℃ at a heating rate of 6℃ / min and held for 12h. Finally, the temperature is lowered to room temperature at a cooling rate of 25℃ / min. Then, the head and tail are sawed and the surface is milled to obtain a homogenized aluminum-lithium alloy ingot.

[0078] S1.3: Remove the oxide scale from the surface of the homogenized aluminum-lithium alloy ingot, then heat it to 480℃, and upset it sequentially along the X / Y / Z axes in a forging machine. The deformation amount in each pass is 60%, and the cycle is repeated 3 times. Then, transfer it to a warm rolling mill, control the speed ratio of the upper roll speed to the lower roll speed to be 1:1.2, the rolling temperature to be 350℃, the reduction per pass to be 20%, and the final rolling thickness to be 7mm. Then, cold roll it with a reduction of 10% per pass to obtain a final rolling thickness of 2.5mm to obtain an aluminum-lithium alloy sheet.

[0079] S1.4: The aluminum-lithium alloy sheet is dissolved at 480℃ for 1 hour, then dissolved at 510℃ for 1.2 hours, and then quenched in water to room temperature to obtain a high-strength aluminum-lithium alloy profile.

[0080] S2: Construction of an alumina array layer on the surface of an aluminum-lithium alloy

[0081] S2.1: The high-strength aluminum-lithium alloy profile is placed in deionized water containing 5wt% sodium dodecylbenzenesulfonate and treated with a 40kHz ultrasonic cleaner for 12 minutes. After being removed, it is immersed in anhydrous ethanol and ultrasonically cleaned for 10 minutes. After rinsing with deionized water 4 times, it is placed in a vacuum drying oven at 45℃ for 1.5 hours to obtain a clean aluminum-lithium alloy profile.

[0082] S2.2: Aluminum acetate trihydrate was placed in anhydrous ethanol and stirred for 40 min in a water bath at 70°C to obtain an aluminum acetate ethanol solution with a concentration of 15 mmol / L. The clean aluminum-lithium alloy profile was immersed in the aluminum acetate ethanol solution and pulled up 4 times at a uniform speed. Then it was placed in a muffle furnace and heated to 200°C at a heating rate of 10°C / min and held for 1.5 h. After natural cooling, it was pulled up 4 times at a uniform speed of 8 cm / min in the aluminum acetate ethanol solution and held in a muffle furnace at 200°C for 1.5 h. The pulling-holding operation was repeated 3 times to obtain an Al2O3 seed layer aluminum-lithium alloy profile.

[0083] S2.3: Prepare an aluminum nitrate solution with a concentration of 60 mmol / L and place it in a container. Then add an equal volume of hexamethylenetetramine solution with a concentration of 60 mmol / L. Stir magnetically at 100 rpm for 20 h at room temperature to obtain an array growth solution. Vertically immerse the Al2O3 seed layer aluminum-lithium alloy profile into the array growth solution and then transfer it to a 95℃ oven for 10 h. After cooling, wash it three times with anhydrous ethanol and deionized water in sequence, and dry it at 65℃ to constant weight to form an alumina array layer, thus obtaining an alumina array layer aluminum-lithium alloy profile.

[0084] S3: Thermal insulation treatment of aluminum-lithium alloy profiles with alumina array layer

[0085] S3.1: Melamine, formaldehyde, urea and deionized water are added to a container in a mass ratio of 1:3.85:0.95:4 and mixed evenly. Triethanolamine is added to adjust the pH to 9. Then the mixture is stirred at 85℃ and 500rpm for 35min to obtain melamine prepolymer.

[0086] S3.2: Styrene-maleic anhydride, sodium hydroxide, and deionized water were mixed in a mass ratio of 1:0.4:9 and placed in a container. The mixture was heated at 85°C for 1.5 h to obtain a styrene-maleic anhydride solution. The styrene-maleic anhydride solution, melamine prepolymer, and n-octadecane were mixed in a mass ratio of 1:4.5:1 and placed in a high-speed emulsifier. The mixture was emulsified at 6500 rpm for 30 min. Acetic acid was then added dropwise to adjust the pH to 6. The mixture was heated in a water bath at 55°C and 500 rpm for 35 min. The temperature was then increased to 75°C and heated in a water bath for 3 h. The precipitate was collected by filtration, rinsed with deionized water, and dried to obtain melamine microcapsules.

[0087] S3.3: Add polyvinyl alcohol to distilled water and stir at 90°C until the polyvinyl alcohol is fully dissolved. Let it stand and cool to room temperature to prepare a 10% PVA solution. Add 1 mol / L calcium nitrate solution and melamine microcapsules to the PVA solution and mix well. Then slowly add 1 mol / L sodium silicate solution. The mass ratio of calcium nitrate solution: melamine microcapsules: sodium silicate solution: PVA solution is 1:0.04:1.2:3 to obtain a melamine microcapsule-calcium silicate nano suspension.

[0088] S3.4: Place the aluminum-lithium alloy profile with alumina array layer in a vacuum filtration tank, evacuate to 1000 Pa and maintain for 35 min, then adjust to normal pressure, add melamine microcapsule-calcium silicate nano suspension to immerse the aluminum-lithium alloy profile with alumina array layer, continue to evacuate to 500 Pa and maintain for 2 h, take it out and dry at 50℃ to constant weight, forming melamine microcapsule-calcium silicate nano aerogel in the alumina array layer, and obtain a high-strength heat-insulating aluminum profile.

[0089] Comparative Example 1: The difference from Example 1 is that step S2 is removed in this comparative example, and the aluminum-lithium alloy profile of the alumina array layer in step 3.4 is replaced with a high-strength aluminum-lithium alloy profile. All other specific implementation methods are the same as in Example 1.

[0090] Comparative Example 2: The difference from Example 1 is that melamine microcapsules were not added in step S3.3 to prepare calcium silicate nano suspension. Instead, the melamine microcapsule-calcium silicate nano suspension in step S3.4 was replaced with calcium silicate nano suspension. All other specific implementation methods are the same as in Example 1.

[0091] The high-strength thermally insulated aluminum profiles prepared in Examples 1-3 were used as samples, and their mechanical properties were tested on an electronic universal testing machine at room temperature using 10... -3 s -1 The yield strength, compressive strength and fracture compressibility of the samples were obtained at a constant strain rate. Each group of samples was measured 3 times and the average value of the results was taken, as shown in Table 1.

[0092] Table 1: Compression performance of high-strength thermally insulated aluminum profiles

[0093]

[0094] As can be seen from the data of Examples 1-3 in Table 1, the high-strength thermal insulation aluminum profile prepared in this application has excellent compressive properties. This proves that by optimizing the aluminum alloy formula and controlling the component ratio, using Cu, Li, and Zn as the base and introducing rare earth elements Pr, Sc, and Zr for synergistic strengthening, and by regulating the preparation process of the aluminum-lithium alloy profile, the alloy can achieve high compressive properties under the premise of lightweighting, and its overall performance is superior to that of the traditional Al-Li alloy system.

[0095] The high-strength thermal insulation aluminum profiles prepared in Examples 1-3 and Comparative Example 1, and the aluminum-lithium alloy profile with an alumina array layer prepared in Comparative Example 2 were used as samples. The thermal conductivity of each sample was tested according to the standard of "Determination of Steady-State Thermal Resistance and Related Properties of Thermal Insulation Materials by Heat Flow Meter Method" (GB / T10295-2008). Each sample was tested 3 times, as shown in Table 2.

[0096] Table 2: Thermal conductivity of aluminum profiles

[0097]

[0098] As can be seen from the data in Examples 1-3 in Table 2, the high-strength thermally insulated aluminum profile prepared in this application has low thermal conductivity. As can be seen from Comparative Example 1, without the alumina array layer constructed on the surface of the clean aluminum-lithium alloy profile, its thermal conductivity is significantly increased and its thermal insulation capacity is significantly decreased. This proves that the regular alumina array layer can form a closed air chamber inside, effectively suppressing gas thermal convection. Furthermore, its regular stacked structure can efficiently absorb and scatter thermal radiation photons, enhancing the thermal insulation capacity. As can be seen from Comparative Example 2, without melamine microcapsules filling the regular pore structure of the alumina array layer, the thermal conductivity of the aluminum profile increases and its thermal insulation capacity decreases. This proves that the melamine microcapsules and calcium silicate nanoparticles form an aerogel network structure connected in the inner wall of the pore structure, which can further enhance the thermal insulation capacity of the aluminum profile, ensuring lightweight while giving the aluminum profile excellent thermal insulation capacity.

[0099] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A high-strength thermally insulated aluminum profile, comprising a high-strength aluminum-lithium alloy profile, an alumina array layer, and melamine microcapsules-calcium silicate nano-aerogel, wherein the composition of the high-strength aluminum-lithium alloy profile, by mass percentage, is: Cu: 1.35-2%, Li: 1.9-2.3%, Zn: 5.2-6%, Mg: 0.8-1%, Pr: 0.25-0.4%, Sc: 0.15-0.25%, Zr: 0.08-0.12%, with the balance being Al and unavoidable impurities; The alumina array layer is attached to the surface of the high-strength aluminum-lithium alloy profile, and the melamine microcapsule-calcium silicate nano-aerogel fills the interior of the alumina array layer. The preparation method of the melamine ester microcapsule-calcium silicate nanoaerogel is as follows: After high-speed emulsification of styrene-maleic anhydride solution, melamine prepolymer, and n-octadecane, the pH was adjusted and the reaction was carried out by water bath heating. The precipitate was collected, washed, and dried to obtain melamine microcapsules. Then, melamine microcapsules and calcium nitrate solution were added to PVA solution and sodium silicate solution was slowly added dropwise to obtain melamine microcapsule-calcium silicate nanosuspension. Aluminum-lithium alloy profiles of alumina array layer were placed in the melamine microcapsule-calcium silicate nanosuspension for vacuum impregnation and then dried, so that melamine microcapsules and calcium silicate nanoparticles formed an aerogel network structure and were connected to the inner wall of the alumina array layer, resulting in melamine microcapsule-calcium silicate nanoaerogel filling the interior of the alumina array layer.

2. A manufacturing process for the high-strength heat-insulating aluminum profile according to claim 1, characterized in that, Includes the following steps: S1: Preparation of high-strength aluminum-lithium alloy profiles; S2: Construction of an alumina array layer on the surface of an aluminum-lithium alloy; S3: Thermal insulation treatment of aluminum-lithium alloy profiles with alumina array layer.

3. The manufacturing process of a high-strength heat-insulating aluminum profile according to claim 2, characterized in that, Step S1, the preparation of high-strength aluminum-lithium alloy profiles, specifically includes the following steps: S1.1: The elements are present in the following mass percentages: 1.35-2% Cu, 1.9-2.3% Li, 5.2-6% Zn, 0.8-1% Mg, 0.25-0.4% Pr, 0.15-0.25% Sc, 0.08-0.12% Zr, and the balance Al. Pure Al ingots are added to a melting furnace and melted at 750-800℃. The temperature is then lowered to 720-740℃, and argon gas is introduced as a protective gas. Pure Cu ingots are then added sequentially... Pure Li ingots, pure Zn ingots, pure Mg ingots, as well as Al-15wt%Pr master alloys, Al-13wt%Zr master alloys, and Al-10wt%Sc master alloys, are thoroughly stirred and degassed after complete melting. After standing for 5-10 minutes, they are poured into molds and first water-cooled to 400-420℃ at a cooling rate of 10-15℃ / s, and then air-cooled to room temperature at a cooling rate of 2-3℃ / s to obtain aluminum-lithium alloy ingots. S1.2: Place the aluminum-lithium alloy ingot into an atmosphere sintering furnace, first heat it to 480-485℃ at a heating rate of 10-12℃ / min and hold it for 8-10 hours, then heat it to 520-525℃ at a heating rate of 5-6℃ / min and hold it for 10-12 hours, and finally cool it down to room temperature at a cooling rate of 20-25℃ / min. Then, saw off the head and tail and mill the surface to obtain a homogenized aluminum-lithium alloy ingot. S1.3: Remove the oxide scale from the surface of the homogenized aluminum-lithium alloy ingot, then heat it to 450-480℃, and upset it sequentially along the X / Y / Z axes in a forging machine. The deformation amount per pass is 55-60%, and the cycle is repeated 3 times. Then transfer it to a warm rolling mill, control the speed ratio of the upper roll speed to the lower roll speed to be 1:(1.1-1.2), the rolling temperature to be 330-350℃, the reduction per pass to be 10-20%, and the final rolling thickness to be 5-7mm. Then cold roll it with a reduction of 5-10% per pass to a final rolling thickness of 2-2.5mm to obtain aluminum-lithium alloy sheets. S1.4: The aluminum-lithium alloy sheet is dissolved at 460-480℃ for 0.5-1h, then dissolved at 500-510℃ for 1-1.2h, and then water-quenched to room temperature to obtain a high-strength aluminum-lithium alloy profile.

4. The manufacturing process of a high-strength heat-insulating aluminum profile according to claim 3, characterized in that, Step S2 involves constructing the alumina array layer on the surface of the aluminum-lithium alloy, specifically including the following steps: S2.1: Place the high-strength aluminum-lithium alloy profile in deionized water containing 5wt% sodium dodecylbenzenesulfonate and treat it with an ultrasonic cleaner at 35-40kHz for 10-12 minutes. After taking it out, immerse it in anhydrous ethanol and repeat the ultrasonic cleaning for 8-10 minutes. Rinse it with deionized water 3-4 times and then place it in a vacuum drying oven at 40-45℃ for 1-1.5 hours to obtain a clean aluminum-lithium alloy profile. S2.2: Place aluminum acetate trihydrate in anhydrous ethanol, and then stir for 30-40 min in a water bath at 60-70℃ to obtain an aluminum acetate ethanol solution with a concentration of 10-15 mmol / L. Immerse the clean aluminum-lithium alloy profile in the aluminum acetate ethanol solution and pull it up at a uniform speed 3-4 times. Then place it in a muffle furnace and heat it to 180-200℃ at a heating rate of 5-10℃ / min and hold it for 1-1.5 h. After natural cooling, pull it up at a uniform speed 3-4 times in the aluminum acetate ethanol solution and hold it in a muffle furnace at 180-200℃ for 1-1.5 h. Repeat the pulling-holding operation 2-3 times to obtain an Al2O3 seed layer aluminum-lithium alloy profile. S2.3: Prepare an aluminum nitrate solution with a concentration of 50-60 mmol / L and place it in a container. Then add an equal volume of hexamethylenetetramine solution with a concentration of 50-60 mmol / L. Stir magnetically at 80-100 rpm for 18-20 hours at room temperature to obtain an array growth solution. Vertically immerse the Al2O3 seed layer aluminum-lithium alloy profile into the array growth solution and then transfer it to an oven at 90-95℃ for 8-10 hours. After cooling, wash it 2-3 times with anhydrous ethanol and deionized water in sequence, and dry it at 60-65℃ to constant weight to form an alumina array layer, thus obtaining an alumina array layer aluminum-lithium alloy profile.

5. The manufacturing process of a high-strength heat-insulating aluminum profile according to claim 4, characterized in that, Step S3, the thermal insulation treatment of the aluminum-lithium alloy profile with an alumina array layer, specifically includes the following steps: S3.1: Melamine, formaldehyde, urea and deionized water are added to a container in a mass ratio of 1:(3.8-3.85):(0.9-0.95):(3.85-4) and mixed evenly. Triethanolamine is added to adjust the pH to 8.5-9. Then, the mixture is stirred at 80-85℃ and 450-500rpm for 30-35min to obtain melamine ester prepolymer. S3.2: Styrene-maleic anhydride, sodium hydroxide, and deionized water are mixed in a mass ratio of 1:(0.3-0.4):(8.5-9) and placed in a container. The mixture is heated at 80-85℃ for 1-1.5h to obtain a styrene-maleic anhydride solution. The styrene-maleic anhydride solution, melamine prepolymer, and n-octadecane are mixed in a mass ratio of 1:(4.4-4.5):(0.8-1) and placed in a high-speed emulsifier. The mixture is emulsified at 6000-6500rpm for 25-30min. Acetic acid is then added dropwise to adjust the pH. The mixture is heated in a water bath at 450-500rpm and 50-55℃ for 30-35min. The temperature is then increased to 70-75℃ and heated in a water bath for 2.5-3h. The precipitate is collected by filtration, rinsed with deionized water, and dried to obtain melamine microcapsules. S3.3: Add polyvinyl alcohol to distilled water and stir at 85-90℃ until the polyvinyl alcohol is fully dissolved. Let it stand and cool to room temperature to prepare a PVA solution with a mass concentration of 8-10%. Add 1 mol / L calcium nitrate solution and melamine microcapsules to the PVA solution and mix well. Then slowly add 1 mol / L sodium silicate solution to obtain a melamine microcapsule-calcium silicate nano suspension. S3.4: Place the aluminum-lithium alloy profile with alumina array layer in a vacuum filtration tank, evacuate to 800-1000 Pa and maintain for 30-35 min, then adjust to normal pressure, add melamine microcapsule-calcium silicate nano suspension to immerse the aluminum-lithium alloy profile with alumina array layer, continue evacuating to 400-500 Pa and maintain for 1.5-2 h, take it out and dry at 45-50℃ to constant weight, forming melamine microcapsule-calcium silicate nano aerogel in the alumina array layer, to obtain a high-strength heat-insulating aluminum profile.

6. The manufacturing process of a high-strength heat-insulating aluminum profile according to claim 3, characterized in that, The gas used for degassing and slag removal in step S1.1 is hexachloroethane.

7. The manufacturing process of a high-strength heat-insulating aluminum profile according to claim 4, characterized in that, In step S2.2, the uniform lifting speed is 6-8 cm / min.

8. The manufacturing process of a high-strength heat-insulating aluminum profile according to claim 5, characterized in that, After adjusting the pH by adding acetic acid in step S3.2, the pH of the mixed solution of styrene-maleic anhydride, melamine prepolymer, and n-octadecane is 5.5-6.

9. The manufacturing process of a high-strength heat-insulating aluminum profile according to claim 5, characterized in that, In step S3.3, the mass ratio of calcium nitrate solution: melamine microcapsules: sodium silicate solution: PVA solution is 1: (0.03-0.04): (1-1.2): (2-3).

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