Nanopore foam metal composite water storage material and preparation method thereof

Abstract

The invention discloses a nanopore foam metal composite water storage material and a preparation method thereof, and belongs to the technical field of water storage material preparation. In order to solve the problem of insufficient water storage performance of the metal foam material, the technical means of cold printing precursor preparation, hydrogel cold printing, heat treatment and pressurized liquid filling are mainly adopted. Acrylamide is used as a responsive matrix, polyethylene glycol is used as a thickening agent to prepare a precursor solution, hydrogel is formed through cold printing induction, then a metal nano foam material with a homogeneous through hole structure is prepared through heat treatment, and finally efficient storage of liquid is achieved through a pressurized liquid filling method. According to the invention, the uniform distribution of the pore diameter at the nanoscale can be realized, and the liquid storage volume and stability are obviously improved.

Description

Technical Field

[0001] The present invention particularly provides a nano-porous foam metal composite water storage material and a preparation method thereof, belonging to the technical field of water storage material preparation. Background Art

[0002] The composite water storage material consists of a carrier and water, and realizes the purpose of heat prevention through water evaporation, having broad application prospects. Under the existing technology, the carrier usually selects organic resin foam, with a mature process, but having the disadvantages of low self-strength and poor heat resistance. The nano-porous foam metal, as a metal porous material, consists of a continuous phase skeleton and nano-pores, having both the excellent mechanical properties of metal materials and the new structural and functional characteristics endued by the nano-pore structure, and can be used as the carrier of the new water storage material. Under the existing technology, the methods for preparing foam metal include sintering method, electroplating method, pressure casting method, foaming method, etc., having the disadvantages of high production cost, large energy consumption in the production process, poor pore homogeneity of the prepared foam metal material, large pore size, difficult to achieve nano-pore preparation, and many internal closed pores, unable to achieve the purpose of effective water storage, and unable to prepare complex components with high precision and small size. Therefore, there is an urgent need for a preparation method of nano-porous foam metal composite water storage material. Summary of the Invention

[0003] The purpose of the present invention is to provide a preparation method of nano-porous foam metal composite water storage material by using cold printing technology, which can solve the problem of low strength of traditional composite water storage materials, and has the characteristics of short process and low energy consumption.

[0004] To achieve the above purpose, the technical scheme adopted by the present invention is as follows:

[0005] A preparation method of nano-porous foam metal composite water storage material includes the following steps:

[0006] 1) Preparation of cold printing precursor: Dissolve acrylamide as a responsive matrix in water, then add polyethylene glycol as a thickening agent to configure a solution; then add metal powder and stir evenly to obtain a precursor solution;

[0007] 2) Cold printing of hydrogel: Transfer the obtained precursor solution to a cold printing device, and while cold printing, induce acrylamide to form a hydrogel to obtain a near-net-shaped hydrogel;

[0008] 3) Heat treatment of hydrogel: Perform heat treatment on the obtained near-net-shaped hydrogel to obtain a metal nano-foam material;

[0009] 4) Pressurized liquid filling: Place the obtained metal nano-foam material in a vacuum tank, evacuate the air, then inject liquid into the vacuum tank to allow the liquid to enter the interior of the metal nano-foam material. After the pressure stabilizes and does not drop, pressurize the vacuum tank, hold the pressure for a certain period of time, then release the pressure and take out the material to complete the liquid filling, obtaining a nano-porous foam metal composite water storage material.

[0010] Further, in step 1), the mass ratio of acrylamide to water is (1 - 3):100, and the mass ratio of polyethylene glycol to water is (1 - 3):100.

[0011] Further, in step 1), the volume ratio of the metal powder to the solution is 1:(2.5 - 5).

[0012] Further, in step 1), the metal powder is selected from aluminum powder or chromium powder, and the particle size is 10 - 1000 nm.

[0013] Further, in step 2), the induction method is selected from photo-initiation or thermal initiation; when the powder content is high, thermal initiation is selected; when the solid content is low, photo-initiation is selected.

[0014] Further, step 3) of the heat treatment mainly includes three steps:

[0015] Heat up to 100 - 150 °C and treat for 30 - 60 min to remove acrylamide in the gel;

[0016] Introduce hydrogen into the furnace, heat up to 350 - 450 °C, keep warm for 30 - 60 min, and perform degumming treatment to remove the remaining polymer molecules;

[0017] Convert the furnace atmosphere to an inert atmosphere for protection, continue to heat up to the sintering temperature to obtain the metal nano-foam material.

[0018] Further, in step 3), the inert atmosphere is one of nitrogen and argon.

[0019] Further, in step 4), when the vacuum pressure is less than 0.01 MPa, inject liquid into the vacuum tank.

[0020] Further, in step 4), the liquid is an inorganic salt aqueous solution.

[0021] Further, in step 4), the pressurization conditions are: pressure 0.1 - 0.3 MPa, hold the pressure for 5 - 10 min.

[0022] A nano-porous foam metal composite water storage material is prepared by the above preparation method.

[0023] The present invention has achieved the following beneficial effects:

[0024] 1. Preparation of cold-printing precursor: The present invention is prepared by the method of cold-printing precursor. Acrylamide is selected as the responsive matrix, and polyethylene glycol (PEG) is used as the thickener. This design can enhance the suspension ability of metal powder in the solution. In subsequent processing, after removing the responsive matrix, PEG can effectively maintain the shape and produce slight shrinkage, thus ensuring the structural integrity of the formed product.

[0025] 2. Hydrogel cold printing: When the metal powder content is high, the light transmittance of the precursor is poor, and a thermal initiator can be selected to form a gel to achieve mold preparation and near-size forming; when the solid content is low, a photoinitiator can be selected to form a gel, and a 3D printing forming effect can be obtained by adjusting the beam shape. The photoinitiator can also achieve the goal of near-net forming during printing by preparing different forms of gratings. After forming, the three-dimensional skeleton built by the gel can make the metal powder evenly distributed in the skeleton.

[0026] 3. Three-step sintering process: The three-step sintering process of the present invention can effectively remove impurities inside the porous metal while maintaining the shape and internal structural integrity of the product. In the preliminary heat treatment stage, the spontaneous shrinkage of the polymer combined with the secondary densification after high-temperature sintering can further improve the coherence inside the porous metal, making the pore size reach the nanometer level.

[0027] 4. Characteristics of metal nano-porous materials: The metal nano-porous materials prepared by the present invention have a homogeneous through-hole structure constructed by a metal skeleton, and the pore sizes are mainly distributed in the sub-micron and micron levels. After filling with liquid, due to the siphon and surface tension effects, the liquid can stably exist in the pores. By adjusting the types and proportions of inorganic salts, the evaporation heat absorption function of the material at different temperatures can be realized.

[0028] 5. Liquid storage capacity: The metal porous materials prepared by the present invention have a continuous, uniform and nano-scale pore structure. Through the siphon and surface tension of the liquid, the storage amount and stability of water in the metal porous materials are ensured. Detailed implementation mode

[0029] To make the technical features and advantages or technical effects in the above technical solutions of the present invention more obvious and understandable, the following is a detailed description in combination with embodiments.

[0030] Example 1:

[0031] Step 1: Preparation of cold-printing precursor. Dissolve acrylamide as the responsive matrix in water at a ratio of 2:100, and add 2% of the water mass of PEG as the thickener to prepare a solution. In the prepared solution, add aluminum powder (particle size 10 - 1000 nm) at a powder:solution volume ratio of 1:4, and stir evenly to obtain the precursor solution.

[0032] Step 2: Cold printing of hydrogel. Transfer the precursor solution to a cold printing device. While cold printing, photoinitiation induces acrylamide to form a hydrogel, obtaining a near-net-shaped hydrogel.

[0033] Step 3: Heat treatment of hydrogel. Heat-treat the obtained near-net-shaped hydrogel in a multi-atmosphere debinding and sintering furnace. First, raise the ambient temperature to 120 °C and treat for 40 min to remove the responsive matrix in the gel; then introduce hydrogen into the furnace to raise the temperature to 400 °C and hold for 50 min for debinding treatment to remove the remaining polymer molecules; finally, change the furnace atmosphere to nitrogen protection and continue to raise the temperature to the sintering temperature to obtain the metal nano-foam material.

[0034] Step 4: Pressurized liquid filling. Place the obtained metal nano-foam material in a vacuum tank and evacuate it. When the vacuum pressure is less than 0.01 MPa, inject an inorganic salt aqueous solution into the vacuum tank to make the liquid enter the interior of the metal nano-foam material. After the pressure stabilizes and does not drop, use a gas pressure bottle to pressurize the vacuum tank, apply a pressure of 0.2 MPa, hold the pressure for 8 min, and then release the pressure and take it out to complete the liquid filling, preparing the nano-porous foam metal composite water storage material.

[0035] Example 2:

[0036] Step 1: Preparation of cold printing precursor. Dissolve acrylamide as the responsive matrix in water at a ratio of 1:100 and add 1% of PEG by mass of the water as a thickener to prepare a solution. In the prepared solution, add chromium powder (particle size 10 - 1000 nm) at a powder:solution volume ratio of 1:2.5 and stir evenly to obtain the precursor solution.

[0037] Step 2: Cold printing of hydrogel. Transfer the precursor solution to a cold printing device. While cold printing, thermal initiation induces acrylamide to form a hydrogel, obtaining a near-net-shaped hydrogel.

[0038] Step 3: Heat treatment of hydrogel. Heat-treat the obtained near-net-shaped hydrogel in a multi-atmosphere debinding and sintering furnace. First, raise the ambient temperature to 100 °C and treat for 60 min to remove the responsive matrix in the gel; then introduce hydrogen into the furnace to raise the temperature to 350 °C and hold for 60 min for debinding treatment to remove the remaining polymer molecules; finally, change the furnace atmosphere to nitrogen protection and continue to raise the temperature to the sintering temperature to obtain the metal nano-foam material.

[0039] Step 4: Pressurizing and liquid filling. Place the obtained metal nano-foam material in a vacuum tank and evacuate it. When the vacuum pressure is less than 0.01 MPa, inject an inorganic salt aqueous solution into the vacuum tank to allow the liquid to enter the interior of the metal nano-foam material. After the pressure stabilizes and does not drop, use a gas pressure bottle to pressurize the vacuum tank, apply a pressure of 0.1 MPa, hold the pressure for 10 min, then relieve the pressure and take out the material to complete the liquid filling, and prepare a nano-porous foam metal composite water storage material.

[0040] Example 3:

[0041] Step 1: Preparation of cold-printing precursor. Dissolve acrylamide, which serves as a responsive matrix, in water at a ratio of 3:100, and add 3% of the mass of water of PEG as a thickener to configure a solution. In the prepared solution, add aluminum powder (particle size 10 - 1000 nm) at a ratio of powder: solution volume of 1:5, and stir evenly to obtain a precursor solution.

[0042] Step 2: Cold printing of hydrogel. Transfer the precursor solution to a cold printing device. While cold printing, photoinitiation induces acrylamide to form a hydrogel to obtain a near-net-shaped hydrogel.

[0043] Step 3: Heat treatment of hydrogel. Perform heat treatment on the obtained near-net-shaped hydrogel in a multi-atmosphere debinding and sintering integrated furnace. First, raise the ambient temperature to 150 °C and process for 30 min to remove the responsive matrix in the gel; then introduce hydrogen into the furnace to raise the temperature to 450 °C and hold for 30 min for debinding treatment to remove the remaining polymer molecules; finally, change the furnace atmosphere to argon protection and continue to raise the temperature to the sintering temperature to obtain a metal nano-foam material.

[0044] Step 4: Pressurizing and liquid filling. Place the obtained metal nano-foam material in a vacuum tank and evacuate it. When the vacuum pressure is less than 0.01 MPa, inject an inorganic salt aqueous solution into the vacuum tank to allow the liquid to enter the interior of the metal nano-foam material. After the pressure stabilizes and does not drop, use a gas pressure bottle to pressurize the vacuum tank, apply a pressure of 0.3 MPa, hold the pressure for 5 min, then relieve the pressure and take out the material to complete the liquid filling, and prepare a nano-porous foam metal composite water storage material.

[0045] Although the present invention has been disclosed as above with embodiments, it is not intended to limit the present invention. Appropriate modifications or equivalent replacements made by those of ordinary skill in the art to the technical solutions of the present invention should be covered within the protection scope of the present invention. The protection scope of the present invention shall be defined by the claims.

Claims

1. A method for preparing a nanoporous metal foam composite water storage material, characterized in that: The following steps are involved: 1) dissolving acrylamide as a responsive matrix in water, and then adding polyethylene glycol as a thickener to prepare a solution; then adding metal powder and stirring evenly to obtain a precursor solution; 2) transferring the obtained precursor solution to a cold printing device, and inducing acrylamide to form a hydrogel during cold printing to obtain a nearly net-shaped hydrogel; 3) heat-treating the obtained nearly net-shaped hydrogel to obtain a metal nano foam material; 4) placing the obtained metal nano foam material in a vacuum tank, evacuating the tank, and then injecting liquid into the vacuum tank to allow the liquid to enter the interior of the metal nano foam material. After the pressure stabilizes and does not drop, pressurizing the vacuum tank, maintaining the pressure for a period of time, and then releasing the pressure and taking it out to complete the liquid filling, thereby obtaining a nanoporous foam metal composite water storage material.

2. The preparation method according to claim 1, characterized in that In step 1), the mass ratio of acrylamide to water is (1-3):100, and the mass ratio of polyethylene glycol to water is (1-3):

100.

3. The preparation method according to claim 1, characterized in that: In step 1), the volume ratio of metal powder to solution is 1:(2.5-5); the metal powder is aluminum powder or chromium powder, and the particle size is 10-1000 nm.

4. The preparation method according to claim 1, characterized in that: In step 2), the induction method is photo-initiation or thermal-initiation.

5. The preparation method according to claim 1, characterized in that: The heat treatment in step 3) mainly includes three steps: Raise the temperature to 100-150°C for 30-60 minutes to remove acrylamide in the gel; Introduce hydrogen into the furnace, raise the temperature to 350-450°C, and keep the temperature for 30-60 minutes to perform degumming treatment to remove the remaining polymer molecules; The atmosphere in the furnace is changed to an inert atmosphere for protection, and the temperature is continued to be raised to the sintering temperature to obtain the metal nano foam material.

6. The preparation method according to claim 1, characterized in that: The inert atmosphere in step 3) is one of nitrogen and argon.

7. The preparation method according to claim 1, characterized in that: In step 4), when the vacuum pressure is less than 0.01 MPa, liquid is injected into the vacuum tank.

8. The preparation method according to claim 1, characterized in that: The liquid in step 4) is an inorganic salt aqueous solution.

9. The preparation method according to claim 1, characterized in that: The pressurizing conditions in step 4) are: pressure 0.1-0.3 MPa, and pressure maintenance for 5-10 minutes.

10. A nanoporous metal foam composite water storage material, prepared by the preparation method according to any one of claims 1 to 9.