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CN-121988741-A - Preparation method and application of nano porous foam aluminum material

CN121988741ACN 121988741 ACN121988741 ACN 121988741ACN-121988741-A

Abstract

The invention discloses a preparation method and application of a nano porous foam aluminum material, and belongs to the technical field of porous metal materials. The method comprises the steps of mixing main aluminum powder with aluminum powder waste coated by SiO 2 , preparing a three-layer core-shell pore-forming agent which has a PMMA inner core/Sn-Bi alloy middle layer/Al 2 O 3 outer layer structure and PMMA particle sizes distributed in a gradient manner (50-100 nm on the surface layer, 200-300nm on the middle layer and 400-500nm on the core layer), performing cold press molding, performing two-stage step sintering, wherein the Sn-Bi alloy is melted at a low temperature in N 2 -H 2 atmosphere to coat the aluminum powder, and the PMMA pore-forming agent is decomposed at a high temperature under vacuum, carbon-containing gas and pressure in the second stage to generate Al 4 C 3 reinforcing phase in situ. The high-performance fireproof, catalytic and electromagnetic shielding functional materials can be further prepared by compounding Al 4 C 3 /expanded graphite on the surface, growing ZnO nano rods/Pt in situ or compounding carbon nano tubes in situ, and the high-performance fireproof, catalytic and electromagnetic shielding functional materials can be widely applied to the fields of new energy batteries, environmental protection catalysis and 5G communication.

Inventors

  • MA TIANWEI
  • XU HUI
  • SUN HAO
  • ZHANG JIN
  • NIE GANG

Assignees

  • 安徽省新方尊自动化科技有限公司

Dates

Publication Date
20260508
Application Date
20260202

Claims (8)

  1. 1. The preparation method of the nano porous foam aluminum material is characterized by comprising the following steps of: (1) Preparing raw materials: Mixing aluminum powder, namely mixing main aluminum powder with the particle size of 0.5-5 mu m with SiO 2 coated and modified aluminum powder waste according to the volume ratio of 9:1, wherein the purity of the total aluminum powder is more than or equal to 99.9%; Preparing a pore-forming agent, namely preparing a three-layer core-shell pore-forming agent with a PMMA core/Sn-Bi alloy middle layer/Al 2 O 3 outer layer structure by adopting a layered coating method; (2) Cold press molding, namely mixing the mixed aluminum powder obtained in the step (1) with the three-layer core-shell pore-forming agent according to the volume ratio of 80:20, cold press molding under the pressure of 200-300MPa in inert atmosphere, and maintaining the pressure for 10-15 minutes to obtain a green body; (3) Step sintering is regulated and controlled in an atmosphere sectional mode: Firstly, introducing an N 2 -H 2 mixed atmosphere with the volume ratio of H 2 percent into a sintering furnace, heating to 280-320 ℃ at the heating rate of 2-4 ℃ per minute, and preserving heat for 2-3 hours to enable the Sn-Bi alloy interlayer to be melted and wrap aluminum powder particles; The second stage is to vacuumize the sintering furnace until the pressure is less than or equal to 1X 10 -2 Pa, raise the temperature to 550-600 ℃ at the temperature raising rate of 4-6 ℃ per minute, introduce carbon-containing gas, apply external pressure of 1-2MPa, keep the temperature for 1.5-2.5 hours, decompose and escape the PMMA inner core to form nano-pores, and generate Al 4 C 3 reinforced phase on the surface of the pore wall in situ, thus finally obtaining the nano-porous foam aluminum material with a gradient pore structure; The gradient pore structure is realized by using pore formers with different PMMA inner core particle sizes, specifically, the pore formers for forming the surface layer, the PMMA inner core particle size of which is 50-100nm, the pore formers for forming the middle layer, the PMMA inner core particle size of which is 200-300nm, and the pore formers for forming the core layer, and the PMMA inner core particle size of which is 400-500nm.
  2. 2. The preparation method according to claim 1, wherein the particle size of the aluminum powder waste is less than 0.5 μm, and the modification treatment comprises ball milling for 2 hours at a rotational speed of 300r/min, and then coating a SiO 2 layer with a thickness of 5-8nm by adopting a sol-gel method, wherein the mass ratio of the tetraethoxysilane to the aluminum powder waste is 1:10.
  3. 3. The preparation method according to claim 1, wherein in the three-layer core-shell pore-forming agent, the particle size of the PMMA core ranges from 50nm to 500nm, the melting point of the Sn-Bi alloy intermediate layer ranges from 230 ℃ to 250 ℃ and the thickness of the Al 2 O 3 outer layer ranges from 10 nm to 20nm.
  4. 4. The method according to claim 1, wherein in the second stage of the step (3), the carbon-containing gas is a mixture of acetylene and argon, wherein the flow rate of acetylene is 30-50mL/min.
  5. 5. The nano porous foamed aluminum material prepared by the preparation method of any one of claims 1 to 4, which is characterized by having a gradient pore structure gradually increasing from a surface layer to a core layer, wherein the pore size is 50-500nm, the open porosity is more than or equal to 90%, the porosity is 70-95%, the specific surface area is in gradient distribution, the specific surface area of the surface layer is more than or equal to 45m2/g, the specific surface area of the core layer is more than or equal to 18m2/g, and the compressive strength is more than or equal to 110MPa when the porosity is 70%.
  6. 6. The nano porous foam aluminum material with fireproof function is characterized in that the surface of the nano porous foam aluminum material as claimed in claim 5 is sequentially compounded with: The thickness of the Al 2 O 3 insulating layer deposited by plasma spraying is 4-6 mu m, and the volume resistivity is more than or equal to 1 multiplied by 10 14 omega cm; the thickness of the expanded graphite flame-retardant layer formed by dip coating is 8-12 mu m, and the expansion rate of the expanded graphite flame-retardant layer at 600 ℃ is more than or equal to 5mm/s.
  7. 7. A catalytic nanoporous foamed aluminum material, characterized in that on the pore wall surface of the nanoporous foamed aluminum material according to claim 5: Growing ZnO nano rods with the length of 50-100nm in situ by a hydrothermal method; The ZnO nano rod is loaded with 0.3-0.7wt% of Pt active component by an immersion reduction method, and the dispersity is more than or equal to 80%.
  8. 8. The nano porous foam aluminum material with the electromagnetic shielding function is characterized by being formed by compounding the nano porous foam aluminum material of claim 5 and carbon nano tubes with the diameters of 10-20nm according to the mass ratio of 95:5.

Description

Preparation method and application of nano porous foam aluminum material Technical Field The invention relates to the technical field of porous metal materials, in particular to a multifunctional nano porous foam aluminum material with a gradient pore diameter structure and a powder metallurgy preparation method thereof. The material is particularly suitable for the fields with strict requirements on the cooperation of the structure and the function, such as fire prevention of new energy batteries, environmental protection catalysis, electromagnetic shielding of electronic equipment and the like. Background The nano porous foam aluminum has application potential in a plurality of front fields due to light weight, high specific surface area and good electric conduction and thermal conductivity. However, the nanoporous aluminum foam prepared by the prior art has significant drawbacks, which limit its practical application. Firstly, most of the existing materials are distributed in a single pore diameter, and high specific surface area and high compressive strength are difficult to realize simultaneously, so that the thermal barrier property and the structural support property cannot be considered in the new energy battery fireproof field. Secondly, traditional pore formers (such as single PMMA or carbonate) tend to cause metal agglomeration or aluminum powder oxidation during sintering, affecting material structural uniformity and support performance, especially in catalytic applications leading to reduced active sites and reduced catalyst life. In addition, in the field of electromagnetic shielding, the existing foamed aluminum material has contradiction between shielding effectiveness and light weight, and has serious attenuation of performance in a high-frequency band (such as 5G millimeter wave) and lacks long-acting corrosion resistance and stability. Therefore, there is an urgent need in the art for a nano porous foam aluminum material capable of realizing a structure-function integrated design, having gradient pores, high strength and low oxidation rate, and flexibly adapting to various functional requirements, and a preparation method thereof. Disclosure of Invention The invention aims to overcome the defects of the prior art and provides a multifunctional nano porous foam aluminum material with a gradient structure and a preparation method thereof. According to the invention, by designing a special three-layer core-shell pore-forming agent and a sectional sintering process, a nano porous structure with gradient pore diameter change from a surface layer to a core layer is successfully constructed, the synergy of high specific surface area and high compressive strength is realized, and an ideal carrier platform is provided for further functional integration. In order to achieve the above purpose, the invention adopts the following technical scheme: in a first aspect, the invention provides a method for preparing a nanoporous aluminum foam material, comprising the steps of: (1) Preparing raw materials: Mixing aluminum powder, namely mixing main aluminum powder with the particle size of 0.5-5 mu m with SiO 2 coated and modified aluminum powder waste according to the volume ratio of 9:1, wherein the purity of the total aluminum powder is more than or equal to 99.9%. The aluminum powder waste (particle size is less than 0.5 μm) is firstly subjected to ball milling modification (300 r/min,2 h), and then a SiO 2 layer with the thickness of 5-8nm is coated by adopting a sol-gel method, wherein the mass ratio of Tetraethoxysilane (TEOS) to the aluminum powder waste is 1:10. And preparing the pore-forming agent, namely preparing the three-layer core-shell pore-forming agent with a PMMA core/Sn-Bi alloy middle layer/Al 2O3 outer layer structure by adopting a layered coating method. Wherein the PMMA core particle size is 50-500nm, the melting point of the Sn-Bi alloy intermediate layer is 230-250 ℃, the thickness of the intermediate layer is 50-80nm, and the thickness of the Al 2O3 outer layer is 10-20nm. In order to construct the gradient pore structure, three pore formers with different PMMA core particle sizes are needed to be prepared, wherein the pore formers are used for forming the surface layer, the PMMA core particle size is 50-100nm, the pore formers are used for forming the middle layer, the PMMA core particle size is 200-300nm, and the pore formers are used for forming the core layer, and the PMMA core particle size is 400-500nm. (2) And (3) cold press molding, namely uniformly mixing the mixed aluminum powder and the three-layer core-shell pore-forming agent according to the volume ratio of 80:20, carrying out cold press molding under the pressure of 200-300MPa under the protection of an argon inert atmosphere, and maintaining the pressure for 10-15 minutes to obtain a green body with a certain shape and strength. (3) Step sintering is regulated and controlled in an atmosphere sectional mode: And in