Foamed aluminum surface microstructure modified efficient sound absorption material

Abstract

The invention relates to the technical field of sound insulation materials, in particular to a foamed aluminum surface microstructure modified efficient sound absorption material which comprises the following raw materials: a foamed aluminum matrix, a surface microstructure modifier, a polymer binder and a pore regulating agent. According to the invention, the surface microstructure modifier can construct a micron / submicron coarse structure on the surface of the foamed aluminum skeleton in situ, so that the sound wave action area is obviously increased; the polymer binder not only can firmly bond all the components, but also has viscoelastic damping characteristics, and can directly dissipate sound energy; the pore regulating agent optimizes the pore channel structure in the material, improves acoustic impedance matching and prolongs the sound wave propagation path.

Description

Technical Field

[0001] This invention relates to the field of sound insulation materials technology, specifically to a high-efficiency sound-absorbing material with microstructure modification on the surface of aluminum foam. Background Technology

[0002] Foamed aluminum sound-absorbing material is a porous metal material made of aluminum or aluminum alloy as the base material through foaming. The core uses a three-dimensional network pore structure to convert sound energy into heat energy after sound waves are reflected and rubbed inside, thus achieving sound absorption and noise reduction. It is widely used in industrial, transportation, construction and other scenarios; at the same time, it also has the characteristics of being lightweight, high-strength, high-temperature resistant and corrosion resistant.

[0003] In existing technologies, the sound absorption mechanism is simple and lacks fine and multi-level control over the sound wave propagation path and energy conversion mode; when the functional components are simply combined, the interface bonding is weak and the synergistic effect is poor, making it difficult to achieve structural stability and functional integration; resulting in low absorption efficiency of materials for mid- and low-frequency sound waves, narrow effective sound absorption bandwidth, and difficulty in meeting the actual needs of wide bandwidth, especially low-frequency noise control.

[0004] Based on this, the present invention provides a highly efficient sound-absorbing material with microstructure modification on the surface of aluminum foam. Summary of the Invention

[0005] The purpose of this invention is to provide a high-efficiency sound-absorbing material with microstructure modification on the surface of aluminum foam. The high-efficiency sound-absorbing material prepared by this invention has a high level of sound absorption coefficient in both low frequency and mid-to-high frequency, indicating that it has better sound absorption performance.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a high-efficiency sound-absorbing material with microstructure modification on the surface of aluminum foam, comprising the following raw materials in parts by weight: 100 parts of aluminum foam matrix, 5-15 parts of surface microstructure modifier, 3-10 parts of polymer binder, and 2-8 parts of pore control agent. The surface microstructure modifier is neodymium iron alloy micro powder; The polymeric binder is a modified acrylate copolymer; The pore control agent is a multi-level porous aluminosilicate.

[0007] Preferably, the preparation steps of the NdFe alloy micro powder are as follows: placing metallic NdFe and electrolytic iron in a melting furnace, melting them uniformly at 1450-1550℃ under argon protection, and casting them into ingots; subjecting the alloy ingots to hydrogen crushing treatment, and then pulverizing them in an air jet mill to obtain NdFe alloy micro powder with a particle size distribution D50 of 5-20μm; placing the obtained micro powder in a tube furnace, and performing surface passivation treatment at 300-450℃ for 0.5-2h under an argon atmosphere containing 1-5% oxygen by volume, to obtain NdFe alloy micro powder with a surface coated with an Nd-O-Fe composite oxide layer.

[0008] Preferably, the hydrogen decomposition process involves: placing the alloy ingot in a pressure-resistant reactor and subjecting it to hydrogen absorption treatment for 2-6 hours at a temperature of 300-500℃ and a hydrogen pressure of 0.1-0.5 MPa; subsequently, under a vacuum of 10... -2 The hydrogen was removed by dehydrogenation treatment at 500-600℃ for 1-3 hours. The brittle alloy block after hydrogen breakage was transferred to an air jet mill and pulverized under argon protection to obtain fine alloy powder with a particle size distribution D50 of 5-20μm.

[0009] Preferably, the mass ratio of neodymium to iron is (20-30):(70-80).

[0010] Preferably, the preparation steps of the modified acrylate copolymer are as follows: dimethylaminoethyl methacrylate, acrylamide, and octadecyl acrylate are added to a four-necked flask, deionized water is added and stirring is started, while dilute sodium hydroxide solution is added dropwise to adjust the pH value to 6.0-7.0 to obtain a monomer premix; N,N'-methylenebisacrylamide is added to the premix as a crosslinking agent, diacetone acrylamide as an auxiliary crosslinking monomer, and azobisisobutyronitrile hydrochloride as an initiator; the system is heated to 60-65℃ and reacted for 2-4 hours, and then heated to 80-85℃ for aging for 1 hour; after the reaction, the product is precipitated, filtered, washed, and vacuum dried at 60-80℃ for 8-12 hours, and then pulverized through a 200-mesh sieve to obtain the modified acrylate copolymer.

[0011] Preferably, the amount of dimethylaminoethyl methacrylate added is 40-60 parts by weight, the amount of acrylamide added is 30-50 parts by weight, and the amount of octadecyl acrylate added is 5-10 parts by weight; the amount of crosslinking agent N,N'-methylenebisacrylamide added is 1-3 parts by weight, the amount of auxiliary crosslinking monomer diacetone acrylamide added is 5-10% of the mass of the crosslinking agent, and the amount of initiator azobisisobutyronitrile hydrochloride added is 0.2-1 parts by weight.

[0012] Preferably, the preparation steps of the multi-level porous aluminosilicate are as follows: Oil shale waste residue is crushed and passed through a 100-mesh sieve using a crusher as raw material. This material is then added to an acid pickling solution and reacted continuously at a constant temperature of 70-75℃ and a stirring speed of 100-150 rpm for 1-2 hours. The pH of the slurry is adjusted to 7 using lime powder. The precipitate is filtered, dried, and crushed through a 200-mesh sieve to obtain acid-modified mineral powder. Crystalline aluminum trichloride is mixed with deionized water and stirred at 50-100 rpm at room temperature to obtain a mixed salt solution. The acid-modified mineral powder is added to the mixed salt solution and reacted at a constant temperature of 70-80℃ and a stirring speed of 100-150 rpm for 2-3 hours. After the reaction, the product is centrifuged, the solid precipitate is collected, and dried at 170-180℃ for 2-3 hours. Finally, it is crushed through a 300-mesh sieve to obtain the multi-level porous aluminosilicate.

[0013] Preferably, the pickling solution is prepared by mixing citric acid, propionic acid and deionized water in a mass ratio of 3:10:87.

[0014] Preferably, the mass ratio of the pickling solution to the oil shale waste is 4:1; the mass ratio of the crystalline aluminum trichloride to the deionized water is 3:10; and the mass ratio of the acid-modified mineral powder to the mixed salt solution is 1:1.

[0015] The preparation of the high-efficiency sound-absorbing material specifically includes the following steps: S1. Pretreatment of aluminum foam: Clean and dry the aluminum foam substrate, then immerse it in 3-5% dilute hydrochloric acid or special aluminum alloy cleaning agent for 3-5 minutes. After taking it out, wash it with deionized water and dry it. S2. Slurry preparation: Mix the surface microstructure modifier, pore regulator and 0.5-1% (by mass) of borax dispersant with the polymer binder, add 1-3 times the total mass of deionized water, first ultrasonically disperse for 5-10 min, then disperse in a high-speed mixer at 1000-1500 rpm for 10-20 min to obtain a uniform pre-dispersed slurry; then add the polymer binder and stir at 200-300 rpm for 5-10 min to obtain a uniform slurry. S3. Coating and Construction: Immerse the foamed aluminum treated in S1 completely into the slurry prepared in S2, apply a vacuum pressure of 0.05-0.15MPa and maintain it for 5-10 minutes to ensure that the slurry fully penetrates the pores; after taking it out, pre-cur it at 80-100℃ for 30-60 minutes, and then cure it at 150-180℃ for 30-60 minutes. S4. Post-treatment: Place the cured material in a forced-air drying oven and heat-treat it at 180-200℃ for 1-2 hours, then allow it to cool naturally to room temperature to obtain a high-efficiency sound-absorbing material with modified surface microstructure.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. In this invention, the passivated neodymium iron alloy micro powder has excellent interfacial affinity with the Nd-O-Fe composite oxide layer on its surface, the aluminum foam matrix, and the polymer binder. After the micro powder is firmly fixed to the aluminum foam skeleton, it can effectively construct a uniformly distributed micron / submicron rough structure, significantly increasing the contact area and friction frequency between the sound wave and the solid surface, and directly enhancing the viscous dissipation of sound energy. The micro-rough interface provides a large number of anchoring points for the subsequent pore control agent, and works together with the binder to form a composite interface of rigid micro-protrusions and viscoelastic transition layers in the macro-pores, synergistically changing the propagation and reflection behavior of sound waves.

[0017] 2. In this invention, the modified acrylate copolymer introduces cationic groups that provide strong electrostatic adsorption, amide groups that form a dense hydrogen bond network, and long-chain alkyl groups that impart cohesive toughness. This structure enables it to achieve strong and uniform bonding between aluminum foam, alloy micropowder, and aluminosilicate through chemical and physical forces, ensuring the integrity of the composite structure. Furthermore, its own cross-linked network can generate significant viscoelastic deformation under the action of sound waves, converting a large amount of sound energy into heat energy for dissipation.

[0018] 3. In this invention, a multi-level porous aluminosilicate is formed using oil shale waste as raw material. Through a specific acid washing and aluminum salt modification process, a gradient pore structure rich in micropores and mesopores is formed. After introducing foamed aluminum pores, it can effectively control the pore size distribution inside the composite material, realizing a continuous transition from millimeter-level foam pores to nano-level mesopores. The gradient structure greatly extends the sound wave propagation path and improves the acoustic impedance matching of sound waves entering the material from the air medium, thereby reducing the interface reflection of incident sound energy, and in particular promoting the capture and absorption of long-wavelength low-frequency sound waves. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application are described clearly and completely.

[0021] Example 1: A high-efficiency sound-absorbing material with microstructure modification on the surface of aluminum foam, comprising the following raw materials in parts by weight: 100 parts aluminum foam matrix, 5 parts surface microstructure modifier, 3 parts polymer binder, and 2 parts pore control agent; The surface microstructure modifier is neodymium iron alloy micro powder; The polymeric binder is a modified acrylate copolymer; The pore control agent is a multi-level porous aluminosilicate.

[0022] The preparation steps of NdFe alloy micro powder are as follows: NdFe and electrolytic iron are placed in a melting furnace, and the furnace temperature is raised to 1450℃ under argon protection to completely melt the metal and stir it thoroughly to ensure uniform composition. Then, the alloy liquid is poured into a preheated metal mold and cooled to obtain NdFe alloy ingots. The alloy ingots are subjected to hydrogen crushing treatment and then pulverized in an air jet mill to obtain NdFe alloy micro powder with a particle size D50 of 5μm. The obtained micro powder is placed in a tube furnace and subjected to surface passivation treatment at 300℃ for 0.5h under an argon atmosphere containing 1% oxygen by volume. After cooling to room temperature with the furnace, NdFe alloy micro powder with an Nd-O-Fe composite oxide layer on the surface is obtained.

[0023] The hydrogen decomposition process involves placing the alloy ingot into a pressure-resistant reactor and treating it with hydrogen absorption for 2 hours at a temperature of 300℃ and a hydrogen pressure of 0.1 MPa; subsequently, the reactor is subjected to a vacuum of 10... -2 The alloy ingot was subjected to dehydrogenation treatment at 500℃ for 1 hour to embrittle it. The brittle alloy block after hydrogen crushing was transferred to an air jet mill and pulverized under argon protection to obtain fine alloy powder with a particle size distribution D50 of 5μm.

[0024] The mass ratio of neodymium to iron is 20:80.

[0025] The preparation steps of the modified acrylate copolymer are as follows: Dimethylaminoethyl methacrylate, acrylamide, and octadecyl acrylate are added to a four-necked flask, followed by the addition of deionized water and stirring. Simultaneously, dilute sodium hydroxide solution is added dropwise to adjust the pH to 6.0, resulting in a monomer premix. High-purity argon gas is continuously purged for 20 minutes to remove dissolved oxygen from the reaction solution. N,N'-methylenebisacrylamide is added to the premix as a crosslinking agent, diacetone acrylamide as an auxiliary crosslinking monomer, and azobisisobutyronitrile hydrochloride as an initiator. The system is heated to 60°C and reacted for 2 hours, with low-speed stirring maintained throughout. The mixture is then heated to 80°C for 1 hour under a slightly positive nitrogen atmosphere to allow the residual monomers to fully react, thereby increasing the conversion rate and promoting polymer chain reorganization, resulting in a product with a more uniform structure and more stable performance. After the reaction, the product is poured into anhydrous ethanol or acetone at a volume three times that of the product, causing the polymer to precipitate out and form flocculent or granular precipitates. The precipitates are collected by filtration and then washed twice with an ethanol / acetone mixture to thoroughly remove unreacted monomers, initiator fragments, and water-soluble impurities. Finally, the precipitates are dried at 60°C for 8 hours and then pulverized through a 200-mesh sieve to obtain the modified acrylate copolymer.

[0026] The amount of dimethylaminoethyl methacrylate added is 40 parts by weight, the amount of acrylamide added is 30 parts by weight, the amount of octadecyl acrylate added is 5 parts by weight; the amount of crosslinking agent N,N'-methylenebisacrylamide added is 1 part by weight, the amount of auxiliary crosslinking monomer diacetone acrylamide added is 5% of the mass of the crosslinking agent, and the amount of initiator azobisisobutyronitrile hydrochloride added is 0.2 parts by weight.

[0027] The preparation steps of hierarchical porous aluminosilicate are as follows: Oil shale waste residue is crushed and passed through a 100-mesh sieve as raw material. It is then added to an acid washing solution and reacted continuously at 70℃ with a stirring speed of 100 rpm for 1 hour. The pH of the slurry is adjusted to 7 with lime powder. The precipitate is filtered and transferred to an oven, where it is dried at 110℃ for 1 hour. The dried lumps are then crushed and passed through a 200-mesh sieve to obtain acid-modified mineral powder. Crystalline aluminum trichloride is mixed with deionized water and stirred at 50 rpm at room temperature until the aluminum trichloride is completely dissolved to obtain a mixed salt solution. The acid-modified mineral powder is added to the mixed salt solution and reacted at 70℃ with a stirring speed of 100 rpm for 2 hours. After the reaction, the product is centrifuged, the solid precipitate is collected and dried at 170℃ for 2 hours, and finally crushed and passed through a 300-mesh sieve to obtain hierarchical porous aluminosilicate.

[0028] The pickling solution is prepared by mixing citric acid, propionic acid and deionized water in a mass ratio of 3:10:87.

[0029] The mass ratio of pickling solution to oil shale waste is 4:1; the mass ratio of crystalline aluminum trichloride to deionized water is 3:10; and the mass ratio of acid-modified mineral powder to mixed salt solution is 1:1.

[0030] The preparation of high-efficiency sound-absorbing materials specifically includes the following steps: S1. Pretreatment of aluminum foam: Clean and dry the aluminum foam substrate, then immerse it in 3% dilute hydrochloric acid or special aluminum alloy cleaning agent for 3 minutes, take it out, wash it with deionized water and dry it. S2. Slurry preparation: Mix the surface microstructure modifier, pore regulator and 0.5% (by mass) of borax dispersant with the polymer binder, add 1 times the total mass of deionized water, first ultrasonically disperse for 5 min, then disperse at 1000 rpm for 10 min in a high-speed mixer to obtain a uniform pre-dispersed slurry; then add the polymer binder and stir at 200 rpm for 5 min to obtain a uniform slurry; S3. Coating and Construction: The aluminum foam treated in S1 is completely immersed in the slurry prepared in S2. A vacuum pressure of 0.05 MPa is applied and maintained for 5 minutes to ensure that the slurry fully penetrates the pores. After removal, it is pre-cured at 80°C for 30 minutes and then cured at 150°C for 30 minutes. S4. Post-treatment: The cured material is placed in a forced-air drying oven and heat-treated at 180℃ for 1 hour, and then naturally cooled to room temperature to obtain a high-efficiency sound-absorbing material with modified surface microstructure.

[0031] Example 2: A high-efficiency sound-absorbing material with microstructure modification on the surface of aluminum foam, comprising the following raw materials in parts by weight: 100 parts aluminum foam matrix, 10 parts surface microstructure modifier, 6.5 parts polymer binder, and 5 parts pore control agent; The surface microstructure modifier is neodymium iron alloy micro powder; The polymeric binder is a modified acrylate copolymer; The pore control agent is a multi-level porous aluminosilicate.

[0032] The preparation steps of NdFe alloy micro powder are as follows: NdFe and electrolytic iron are placed in a melting furnace, and the furnace temperature is raised to 1500℃ under argon protection to completely melt the metal and stir it thoroughly to ensure uniform composition. Then, the alloy liquid is poured into a preheated metal mold and cooled to obtain NdFe alloy ingots. The alloy ingots are subjected to hydrogen crushing treatment and then pulverized in an air jet mill to obtain NdFe alloy micro powder with a particle size D50 of 12μm. The obtained micro powder is placed in a tube furnace and subjected to surface passivation treatment at 370℃ for 1.2h under an argon atmosphere containing 3% oxygen by volume. After cooling to room temperature with the furnace, NdFe alloy micro powder with an Nd-O-Fe composite oxide layer on the surface is obtained.

[0033] The hydrogen decomposition process involves placing the alloy ingot in a pressure-resistant reactor and treating it with hydrogen absorption for 4 hours at a temperature of 400℃ and a hydrogen pressure of 0.3 MPa; subsequently, the reactor is subjected to a vacuum of 10... -2 The alloy ingot was subjected to dehydrogenation treatment at 550℃ for 2 hours to embrittle it. The brittle alloy block after hydrogen breakage was transferred to an air jet mill and pulverized under argon protection to obtain fine alloy powder with a particle size distribution D50 of 12μm.

[0034] The mass ratio of neodymium to iron is 25:75.

[0035] The preparation steps of the modified acrylate copolymer are as follows: Dimethylaminoethyl methacrylate, acrylamide, and octadecyl acrylate are added to a four-necked flask, followed by the addition of deionized water and stirring. Simultaneously, dilute sodium hydroxide solution is added dropwise to adjust the pH to 6.5, resulting in a monomer premix. High-purity argon gas is continuously purged for 25 minutes to remove dissolved oxygen from the reaction solution. N,N'-methylenebisacrylamide is added to the premix as a crosslinking agent, diacetone acrylamide as an auxiliary crosslinking monomer, and azobisisobutyronitrile hydrochloride as an initiator. The system is heated to 62°C and reacted for 3 hours, with low-speed stirring maintained throughout. The mixture is then heated to 82°C for 1 hour under a slightly positive nitrogen atmosphere to allow the residual monomers to fully react, thereby increasing the conversion rate and promoting polymer chain reorganization, resulting in a product with a more uniform structure and more stable performance. After the reaction, the product is poured into anhydrous ethanol or acetone at a volume of 4 times the product volume, causing the polymer to precipitate out and form flocculent or granular precipitates. The precipitates are collected by filtration and then washed three times with an ethanol / acetone mixture to thoroughly remove unreacted monomers, initiator fragments, and water-soluble impurities. Finally, the precipitates are dried at 70°C for 10 hours and then pulverized through a 200-mesh sieve to obtain the modified acrylate copolymer.

[0036] The amount of dimethylaminoethyl methacrylate added is 50 parts by weight, the amount of acrylamide added is 40 parts by weight, the amount of octadecyl acrylate added is 7.5 parts by weight; the amount of crosslinking agent N,N'-methylenebisacrylamide added is 2 parts by weight, the amount of auxiliary crosslinking monomer diacetone acrylamide added is 7.5% of the mass of the crosslinking agent, and the amount of initiator azobisisobutyronitrile hydrochloride added is 0.6 parts by weight.

[0037] The preparation steps of multi-level porous aluminosilicate are as follows: Oil shale waste residue is crushed and passed through a 100-mesh sieve as raw material. It is then added to an acid washing solution and reacted continuously at a constant temperature of 72℃ and a stirring speed of 125 rpm for 1.5 hours. The pH of the slurry is adjusted to 7 with lime powder. The precipitate is filtered and transferred to an oven, where it is dried at 120℃ for 1.5 hours. The dried lumps are then crushed and passed through a 200-mesh sieve to obtain acid-modified mineral powder. Crystalline aluminum trichloride is mixed with deionized water and stirred at 75 rpm at room temperature until the aluminum trichloride is completely dissolved to obtain a mixed salt solution. The acid-modified mineral powder is added to the mixed salt solution and reacted at a constant temperature of 75℃ and a stirring speed of 125 rpm for 2.5 hours. After the reaction, the product is centrifuged, the solid precipitate is collected and dried at 175℃ for 2.5 hours, and finally crushed and passed through a 300-mesh sieve to obtain multi-level porous aluminosilicate.

[0038] The pickling solution is prepared by mixing citric acid, propionic acid and deionized water in a mass ratio of 3:10:87.

[0039] The mass ratio of pickling solution to oil shale waste is 4:1; the mass ratio of crystalline aluminum trichloride to deionized water is 3:10; and the mass ratio of acid-modified mineral powder to mixed salt solution is 1:1.

[0040] The preparation of high-efficiency sound-absorbing materials specifically includes the following steps: S1. Pretreatment of aluminum foam: Clean and dry the aluminum foam substrate, then immerse it in 3-5% dilute hydrochloric acid or special aluminum alloy cleaning agent for 4 minutes. After taking it out, wash it with deionized water and dry it. S2. Slurry preparation: The surface microstructure modifier, pore regulator and borax dispersant (0.75% by mass of polymer binder) are mixed, and deionized water (twice the total mass) is added. The mixture is first ultrasonically dispersed for 7 minutes, and then dispersed in a high-speed mixer at 1250 rpm for 15 minutes to obtain a uniform pre-dispersed slurry. Subsequently, the polymer binder is added and stirred at 250 rpm for 7 minutes to obtain a uniform slurry. S3. Coating and Construction: The aluminum foam treated in S1 is completely immersed in the slurry prepared in S2, and a vacuum pressure of 0.1 MPa is applied and maintained for 7 minutes to ensure that the slurry fully penetrates the pores; after removal, it is pre-cured at 90°C for 45 minutes, and then cured at 165°C for 45 minutes. S4. Post-treatment: The cured material is placed in a forced-air drying oven and heat-treated at 190℃ for 1.5h, and then naturally cooled to room temperature to obtain a high-efficiency sound-absorbing material with modified surface microstructure.

[0041] Example 3: A high-efficiency sound-absorbing material with microstructure modification on the surface of aluminum foam, comprising the following raw materials in parts by weight: 100 parts aluminum foam matrix, 15 parts surface microstructure modifier, 10 parts polymer binder, and 8 parts pore control agent. The surface microstructure modifier is neodymium iron alloy micro powder; The polymeric binder is a modified acrylate copolymer; The pore control agent is a multi-level porous aluminosilicate.

[0042] The preparation steps of NdFe alloy micro powder are as follows: NdFe and electrolytic iron are placed in a melting furnace, and the furnace temperature is raised to 1550℃ under argon protection to completely melt the metal and stir it thoroughly to ensure uniform composition. Then, the alloy liquid is poured into a preheated metal mold and cooled to obtain NdFe alloy ingots. The alloy ingots are subjected to hydrogen crushing treatment and then pulverized in an air jet mill to obtain NdFe alloy micro powder with a particle size D50 of 20μm. The obtained micro powder is placed in a tube furnace and subjected to surface passivation treatment at 450℃ for 2h under an argon atmosphere containing 5% oxygen by volume. After cooling to room temperature with the furnace, NdFe alloy micro powder with an Nd-O-Fe composite oxide layer on the surface is obtained.

[0043] The hydrogen decomposition process involves placing the alloy ingot in a pressure-resistant reactor and treating it with hydrogen absorption for 6 hours at a temperature of 500℃ and a hydrogen pressure of 0.5 MPa; subsequently, the reactor is subjected to a vacuum of 10... -2 The alloy ingot was subjected to dehydrogenation treatment at 600℃ for 3 hours to embrittle it. The brittle alloy block after hydrogen crushing was transferred to an air jet mill and pulverized under argon protection to obtain fine alloy powder with a particle size distribution D50 of 20μm.

[0044] The mass ratio of neodymium to iron is 30:70.

[0045] The preparation steps of the modified acrylate copolymer are as follows: Dimethylaminoethyl methacrylate, acrylamide, and octadecyl acrylate are added to a four-necked flask, followed by the addition of deionized water and stirring. Simultaneously, dilute sodium hydroxide solution is added dropwise to adjust the pH to 7.0, resulting in a monomer premix. High-purity argon gas is continuously purged for 30 minutes to remove dissolved oxygen from the reaction solution. N,N'-methylenebisacrylamide is added to the premix as a crosslinking agent, diacetone acrylamide as an auxiliary crosslinking monomer, and azobisisobutyronitrile hydrochloride as an initiator. The system is heated to 65°C and reacted for 4 hours, with low-speed stirring maintained throughout. The mixture is then heated to 85°C for 1 hour under a slightly positive nitrogen atmosphere to allow the residual monomers to fully react, thereby increasing the conversion rate and promoting polymer chain reorganization, resulting in a product with a more uniform structure and more stable performance. After the reaction, the product is poured into anhydrous ethanol or acetone at a volume of 5 times the product volume, causing the polymer to precipitate out and form flocculent or granular precipitates. The precipitates are collected by filtration and then washed four times with an ethanol / acetone mixture to thoroughly remove unreacted monomers, initiator fragments, and water-soluble impurities. Finally, the precipitates are dried at 80°C for 12 hours and then pulverized through a 200-mesh sieve to obtain the modified acrylate copolymer.

[0046] The amount of dimethylaminoethyl methacrylate added is 60 parts by weight, the amount of acrylamide added is 50 parts by weight, the amount of octadecyl acrylate added is 10 parts by weight; the amount of crosslinking agent N,N'-methylenebisacrylamide added is 3 parts by weight, the amount of auxiliary crosslinking monomer diacetone acrylamide added is 10% of the mass of the crosslinking agent, and the amount of initiator azobisisobutyronitrile hydrochloride added is 1 part by weight.

[0047] The preparation steps of hierarchical porous aluminosilicate are as follows: Oil shale waste residue is crushed and passed through a 100-mesh sieve as raw material. It is then added to an acid washing solution and reacted continuously at a constant temperature of 75℃ and a stirring speed of 150 rpm for 2 hours. The pH of the slurry is adjusted to 7 with lime powder. The precipitate is filtered and transferred to an oven, where it is dried at 130℃ for 2 hours. The dried lumps are then crushed and passed through a 200-mesh sieve to obtain acid-modified mineral powder. Crystalline aluminum trichloride is mixed with deionized water and stirred at 100 rpm at room temperature until the aluminum trichloride is completely dissolved to obtain a mixed salt solution. The acid-modified mineral powder is added to the mixed salt solution and reacted at a constant temperature of 80℃ and a stirring speed of 150 rpm for 3 hours. After the reaction, the product is centrifuged, the solid precipitate is collected and dried at 180℃ for 3 hours, and finally crushed and passed through a 300-mesh sieve to obtain hierarchical porous aluminosilicate.

[0048] The pickling solution is prepared by mixing citric acid, propionic acid and deionized water in a mass ratio of 3:10:87.

[0049] The mass ratio of pickling solution to oil shale waste is 4:1; the mass ratio of crystalline aluminum trichloride to deionized water is 3:10; and the mass ratio of acid-modified mineral powder to mixed salt solution is 1:1.

[0050] The preparation of high-efficiency sound-absorbing materials specifically includes the following steps: S1. Pretreatment of aluminum foam: Clean and dry the aluminum foam substrate, then immerse it in 5% dilute hydrochloric acid or special aluminum alloy cleaning agent for 5 minutes, take it out, wash it with deionized water and dry it. S2. Slurry preparation: Mix the surface microstructure modifier, pore regulator and borax dispersant (1% by mass of polymer binder) with 3 times the total mass of deionized water, first ultrasonically disperse for 10 min, then disperse in a high-speed mixer at 1500 rpm for 20 min to obtain a uniform pre-dispersed slurry; then add the polymer binder and stir at 300 rpm for 10 min to obtain a uniform slurry. S3. Coating and Construction: The aluminum foam treated in S1 is completely immersed in the slurry prepared in S2. A vacuum pressure of 0.15 MPa is applied and maintained for 10 min to ensure that the slurry fully penetrates the pores. After removal, it is pre-cured at 100°C for 60 min and then cured at 180°C for 60 min. S4. Post-treatment: The cured material is placed in a forced-air drying oven and heat-treated at 200℃ for 2 hours, and then naturally cooled to room temperature to obtain a high-efficiency sound-absorbing material with modified surface microstructure.

[0051] Comparative Example 1: The difference between this comparative example and Example 1 is that this comparative example uses commercially available untreated neodymium iron alloy micro powder.

[0052] Comparative Example 2 differs from Example 1 in that it uses commercially available untreated PU-805 two-component polyurethane adhesive.

[0053] Comparative Example 3 differs from Example 1 in that it uses commercially available untreated aluminosilicate.

[0054] Performance testing: The performance of the high-efficiency sound-absorbing materials prepared in Examples 1, 2, 3, Comparative Examples 1, 2, and 3 was tested. Sound absorption performance test: First, the sample is processed into a specimen that precisely matches the cross-section of the impedance tube and tightly installed in front of the rigid backplate at the end of the tube. During the test, a pure tone of a specific frequency is emitted from a sound source, forming a plane sound wave inside the tube. Subsequently, the probe microphone is moved along the tube axis to accurately detect and record the maximum sound pressure level. and minimum value The standing wave ratio (SWR) is obtained by calculating the ratio of the two. ), and then substitute into the formula Calculate the normal incident sound absorption coefficient at this frequency. Measure each specified frequency in sequence. After taking the values, the arithmetic mean is used to obtain the noise reduction coefficient, which comprehensively reflects the broadband sound absorption performance of the material. The test is based on GB / T 18696.1-2004. Low-frequency sound absorption coefficient (500Hz) test: The sample is prepared as a specimen that matches the cross-section of the impedance tube and is tightly installed in front of the rigid back plate at the end of the tube; for the target low-frequency point, a pure tone signal of that frequency is emitted by the sound source, forming a planar standing wave field inside the tube; the probe microphone is moved along the tube axis to accurately detect and record the maximum and minimum sound pressure values ​​at that frequency; the standing wave ratio is obtained by calculating the ratio of the two, and the normal incident sound absorption coefficient at that specific frequency point is obtained by substituting it into the formula. The test is based on GB / T 18696.1-2004. Mid-to-high frequency sound absorption coefficient (2000Hz) test: In the same frequency sweep measurement, the prepared sample is installed in front of the rigid back plate at the end of the impedance tube; when the test frequency is set to the target mid-to-high frequency point (such as 2000 Hz), a pure tone of that frequency is emitted by the sound source, forming a plane wave in the tube; the probe microphone is moved to detect and record the maximum and minimum sound pressure values ​​at this specific frequency. By calculating the standing wave ratio and substituting it into the formula, the normal incident sound absorption coefficient at this mid-to-high frequency point is obtained. Test standard: GB / T 18696.1-2004.

[0055] The obtained test data are recorded in Table 1 below:

[0056] By comparing and analyzing the relevant data in Table 1, it can be seen that the high-efficiency sound-absorbing material prepared by the microstructure modification of the aluminum foam surface according to this invention has a high level of sound absorption coefficient in both low-frequency and mid-to-high-frequency frequencies, indicating that its sound absorption performance is better. This shows that the high-efficiency sound-absorbing material with microstructure modification of the aluminum foam surface provided by this invention has a broader market prospect and is more suitable for promotion.

[0057] In the description of this specification, references to terms such as "an embodiment," "example," and "specific example" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0058] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A high-efficiency sound-absorbing material with microstructure modification on the surface of aluminum foam, characterized in that, The raw materials include the following parts by weight: 100 parts of aluminum foam matrix, 5-15 parts of surface microstructure modifier, 3-10 parts of polymer binder, and 2-8 parts of pore control agent; The surface microstructure modifier is neodymium iron alloy micro powder; The polymeric binder is a modified acrylate copolymer; The pore control agent is a multi-level porous aluminosilicate.

2. The high-efficiency sound-absorbing material with microstructure modification on the surface of aluminum foam according to claim 1, characterized in that, The preparation steps of the NdFe alloy micro powder are as follows: NdFe and electrolytic iron are placed in a melting furnace and melted uniformly at 1450-1550℃ under argon protection, and then cast into ingots; the alloy ingots are subjected to hydrogen crushing treatment, and then pulverized in an air jet mill to obtain NdFe alloy micro powder with a particle size distribution D50 of 5-20μm; the obtained micro powder is placed in a tube furnace and subjected to surface passivation treatment at 300-450℃ for 0.5-2h under an argon atmosphere containing 1-5% oxygen by volume, to obtain NdFe alloy micro powder with a surface coated with an Nd-O-Fe composite oxide layer.

3. The high-efficiency sound-absorbing material with microstructure modification on the surface of aluminum foam according to claim 2, characterized in that, The hydrogen decomposition process involves placing the alloy ingot in a pressure-resistant reactor and subjecting it to hydrogen absorption treatment for 2-6 hours at a temperature of 300-500℃ and a hydrogen pressure of 0.1-0.5MPa; subsequently, the process is carried out under a vacuum of 10... -2 The hydrogen was removed by dehydrogenation treatment at 500-600℃ for 1-3 hours. The brittle alloy block after hydrogen breakage was transferred to an air jet mill and pulverized under argon protection to obtain fine alloy powder with a particle size distribution D50 of 5-20μm.

4. The high-efficiency sound-absorbing material with microstructure modification on the surface of aluminum foam according to claim 2, characterized in that: The mass ratio of neodymium to iron is (20-30):(70-80).

5. The high-efficiency sound-absorbing material with microstructure modification on the surface of aluminum foam according to claim 1, characterized in that, The preparation steps of the modified acrylate copolymer are as follows: Dimethylaminoethyl methacrylate, acrylamide, and octadecyl acrylate are added to a four-necked flask, deionized water is added and stirring is started, while dilute sodium hydroxide solution is added dropwise to adjust the pH value to 6.0-7.0 to obtain a monomer premix; N,N'-methylenebisacrylamide is added to the premix as a crosslinking agent, diacetone acrylamide as an auxiliary crosslinking monomer, and azobisisobutyronitrile hydrochloride as an initiator; the system is heated to 60-65℃ and reacted for 2-4 hours, and then heated to 80-85℃ for aging for 1 hour; after the reaction, the product is precipitated, filtered, washed, and vacuum dried at 60-80℃ for 8-12 hours, and then pulverized through a 200-mesh sieve to obtain the modified acrylate copolymer.

6. The high-efficiency sound-absorbing material with microstructure modification on the surface of aluminum foam according to claim 5, characterized in that: The amount of dimethylaminoethyl methacrylate added is 40-60 parts by weight, the amount of acrylamide added is 30-50 parts by weight, and the amount of octadecyl acrylate added is 5-10 parts by weight; the amount of crosslinking agent N,N'-methylenebisacrylamide added is 1-3 parts by weight, the amount of auxiliary crosslinking monomer diacetone acrylamide added is 5-10% of the mass of the crosslinking agent, and the amount of initiator azobisisobutyronitrile hydrochloride added is 0.2-1 parts by weight.

7. The high-efficiency sound-absorbing material with microstructure modification on the surface of aluminum foam according to claim 1, characterized in that, The preparation steps of the multi-level porous aluminosilicate are as follows: Oil shale waste residue is crushed and passed through a 100-mesh sieve as raw material. It is then added to an acid pickling solution and reacted continuously at a constant temperature of 70-75℃ and a stirring speed of 100-150 rpm for 1-2 hours. The pH of the slurry is adjusted to 7 with lime powder. The precipitate is filtered, dried, and crushed through a 200-mesh sieve to obtain acid-modified mineral powder. Crystalline aluminum trichloride is mixed with deionized water and stirred at 50-100 rpm at room temperature to obtain a mixed salt solution. The acid-modified mineral powder is added to the mixed salt solution and reacted at a constant temperature of 70-80℃ and a stirring speed of 100-150 rpm for 2-3 hours. After the reaction, the product is centrifuged, the solid precipitate is collected and dried at 170-180℃ for 2-3 hours, and finally crushed through a 300-mesh sieve to obtain the multi-level porous aluminosilicate.

8. The high-efficiency sound-absorbing material with microstructure modification on the surface of aluminum foam according to claim 7, characterized in that: The pickling solution is prepared by mixing citric acid, propionic acid and deionized water in a mass ratio of 3:10:

87.

9. The high-efficiency sound-absorbing material with microstructure modification on the surface of aluminum foam according to claim 7, characterized in that: The mass ratio of the pickling solution to the oil shale waste is 4:1; the mass ratio of the crystalline aluminum trichloride to the deionized water is 3:10; and the mass ratio of the acid-modified mineral powder to the mixed salt solution is 1:

1.

10. The high-efficiency sound-absorbing material with microstructure modification on the surface of aluminum foam according to claim 1, characterized in that, The preparation of the high-efficiency sound-absorbing material specifically includes the following steps: S1. Pretreatment of aluminum foam: Clean and dry the aluminum foam substrate, then immerse it in 3-5% dilute hydrochloric acid or special aluminum alloy cleaning agent for 3-5 minutes. After taking it out, wash it with deionized water and dry it. S2. Slurry preparation: Mix the surface microstructure modifier, pore regulator and 0.5-1% (by mass) of borax dispersant with the polymer binder, add 1-3 times the total mass of deionized water, first ultrasonically disperse for 5-10 min, then disperse in a high-speed mixer at 1000-1500 rpm for 10-20 min to obtain a uniform pre-dispersed slurry; then add the polymer binder and stir at 200-300 rpm for 5-10 min to obtain a uniform slurry. S3. Coating and Construction: Immerse the foamed aluminum treated in S1 completely into the slurry prepared in S2, apply a vacuum pressure of 0.05-0.15MPa and maintain it for 5-10 minutes to ensure that the slurry fully penetrates the pores; after taking it out, pre-cur it at 80-100℃ for 30-60 minutes, and then cure it at 150-180℃ for 30-60 minutes. S4. Post-treatment: Place the cured material in a forced-air drying oven and heat-treat it at 180-200℃ for 1-2 hours, then allow it to cool naturally to room temperature to obtain a high-efficiency sound-absorbing material with modified surface microstructure.

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