A method for preparing nano core-shell Ga-Al@NaIO4 aluminized thermite by electrostatic spraying

Abstract

The application discloses a method for preparing nano core-shell Ga-Al@NaIO4 thermite by an electrostatic spraying method, and comprises the following steps: placing liquid gallium-indium-tin alloy and nano aluminum powder in a solvent for liquid sealing, ultrasonicating, stirring and drying to obtain modified Ga-Al alloy; placing NaIO4 and a binder in a mixed solvent to form a transparent and clear mixed solution; adding the Ga-Al alloy into the mixed solution to form a stable suspension; using a syringe to suck the suspension, fixing the syringe on an electrostatic spraying instrument, receiving the suspension by an aluminum foil baffle, connecting a positive electrode to a needle of the syringe and connecting a negative electrode to the aluminum foil baffle, adjusting process parameters, and making the suspension form a stable spray with a 20-60-degree cone angle at a needle spout to prepare the nano core-shell Ga-Al@NaIO4 thermite. The nano core-shell Ga-Al@NaIO4 thermite prepared by the method has a spherical nano thermite with uniform particle size distribution and good dispersibility, and the two components are both in nano scale, are closely contacted, and have good combustion and heat release performance.

Description

Technical Field

[0001] This invention belongs to the field of energetic materials preparation technology. More specifically, this invention relates to a method for preparing nano-core-shell Ga-Al@NaIO4 aluminothermic agent by electrostatic spraying. Background Technology

[0002] Thermite composites are primarily composed of a mixture of metallic aluminum (Al) and metal or non-metal oxides. When stimulated by external energy, these components undergo vigorous redox reactions, releasing a significant amount of heat. Furthermore, the energy release can be controlled by altering the ratio of metal to oxides, making them widely used in propellants, pyrotechnics, and explosives. However, nano-thermite presents some challenges in practical applications. The oxide layer on the Al surface not only reduces the activity of Al but also decreases the energy release rate of the thermite.

[0003] To address the above problems, solutions mainly involve designing a refined structure, reducing the particle size of aluminum particles, reducing the obstruction of the oxide layer on the aluminum surface through surface modification, and adding other metals to form alloys. Modifying the Al surface inhibits and destroys its oxide film, thereby activating the Al particles and making them more readily react with oxidants, thus improving combustion and heat release performance. Chen An used liquid metal to modify Al and applied it to solid propellants. The results showed that propellants containing modified Al had higher heat release rates and pressurization rates, and smaller condensed phase products.

[0004] Currently, electrostatic spraying technology, as a low-cost, simple, rapid, and continuous production method, has attracted considerable attention from scholars both domestically and internationally, and has been widely applied in the preparation of core-shell structured materials. Electrostatic spraying utilizes a high-voltage electric field to form charged liquid mist particles. Through the interaction of Coulomb forces and surface tension on the particles, a spraying method is used to obtain samples with more uniform component mixing, micro / nano-sized particles, and less agglomeration. Xiao Lei et al. prepared Al / CuO / PVDF / RDX composite microspheres using electrostatic spraying, which significantly improved the thermal and combustion properties of the composite microspheres. Liang Ning et al. prepared RDX / NC / Al composite explosives using electrostatic spraying, which exhibited a shorter ignition delay time, higher combustion rate, and better combustion and safety performance. However, the electrostatic spraying process is relatively slow and has low preparation efficiency, hindering its application in engineering. Summary of the Invention

[0005] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0006] To achieve these and other advantages according to the present invention, a method for preparing nano-core-shell Ga-Al@NaIO4 aluminothermic agent by electrostatic spraying is provided, comprising the following steps: Step 1: Take liquid gallium indium tin alloy and nano aluminum powder, place them in a solvent and seal them, then sonicate, stir and dry to obtain modified Ga-Al alloy; Step 2: Take NaIO4 and binder and place them in a mixed solvent to form a transparent and clear mixed solution; Step 3: Take the Ga-Al alloy obtained in Step 1 and add it to the mixed solution obtained in Step 2 to disperse and form a stable suspension; Step 4: Use a syringe to draw in the suspension, fix it on the electrostatic sprayer, and use an aluminum foil baffle to receive it. Connect the positive electrode to the needle of the syringe and the negative electrode to the aluminum foil baffle. Adjust the process parameters to make the suspension form a stable spray with a cone angle of 20~60° at the nozzle of the needle, thus obtaining the nano-core-shell Ga-Al@NaIO4 aluminothermic agent.

[0007] Preferably, in step one, the mass ratio of gallium, indium, and tin in the gallium-indium-tin alloy is 62:22:16; the content of the gallium-indium-tin alloy is 3wt.%~7wt.%, which is the proportion of the gallium-indium-tin alloy in the total mass of the gallium-indium-tin alloy and the nano-aluminum powder.

[0008] Preferably, in step one, the solvent is one of n-hexane, cyclohexane, n-heptane, ethyl acetate, and acetone; The mass-to-volume ratio of the total mass of gallium indium tin alloy and nano-aluminum powder to the solvent is 1g:15~30mL.

[0009] Preferably, in step one, the ultrasonic time is greater than 30 minutes and the stirring time is greater than 36 hours.

[0010] Preferably, in step two, the mixed solvent is a mixture of solvent I and solvent II, wherein solvent I is N,N-dimethylformamide; solvent II is one of acetone and ethyl acetate; and the volume ratio of solvent I to solvent II is 5:1 to 3:1. The mass-to-volume ratio of NaIO4, total binder, and mixed solvent is 1g:2~4mL.

[0011] Preferably, in step two, the adhesive is one of nitrocellulose, fluororubber, and hydroxyl-terminated azidoglycidyl ether.

[0012] Preferably, the binder content accounts for 2 wt.% to 5 wt.% of the total mass of Ga-Al alloy, NaIO4, and binder, the NaIO4 content is 60 wt.% to 90 wt.%, and the Ga-Al alloy content is 10 wt.% to 40 wt.%.

[0013] Preferably, in step three, the dispersion method is a combination of two or more of magnetic stirring, mechanical stirring, and ultrasonic dispersion, and the dispersion time is 30-60 minutes.

[0014] Preferably, in step four, the process parameters are adjusted as follows: flow rate 0.01~0.05mL / min, negative pressure controlled at -10kV~-12kV, and positive pressure controlled at 10~13kV.

[0015] To further reduce the laser ignition threshold of the core-shell Ga-Al@NaIO4 thermite, in step one, before placing the liquid gallium indium tin alloy and nano-aluminum powder in the solvent for modification, the nano-aluminum powder is pretreated to obtain nano-aluminum powder doped with molybdenum oxide and titanium dioxide. The pretreatment method includes: S1. Weigh a certain amount of ammonium molybdate, tetrabutyl titanate, and nano-aluminum powder and add them to ethanol. Stir and let stand. Then heat to 40~60℃, add dichloromethane as a pore-expanding agent to the suspension, stir evenly and keep warm for 1~3h. After cooling to room temperature, a mixed suspension is obtained. The mass-volume ratio of ammonium molybdate, tetrabutyl titanate, nano-aluminum powder, ethanol, and dichloromethane is 2~10g:10~25mL:60~80g:250~1200mL:5~20mL. S2. The mixed suspension is spray-dried in a liquid nitrogen environment using a sprayer. The suspended particles are exposed to a low temperature environment and rapidly frozen to obtain a mixed powder with a dense pore structure. S3. The mixed powder after spray freeze-drying is subjected to high-temperature calcination at a temperature of 500~800℃ for 1~4h, and then cooled to room temperature in the furnace to obtain nano-aluminum powder doped with molybdenum oxide and titanium dioxide.

[0016] A nano-core-shell Ga-Al@NaIO4 aluminothermic agent, wherein the nano-core-shell Ga-Al@NaIO4 aluminothermic agent has a core-shell structure with a modified Ga-Al alloy as the core and NaIO4 and a binder as the outer shell, and the particle size range of the nano-core-shell Ga-Al@NaIO4 aluminothermic agent is 100nm~500nm.

[0017] The present invention has at least the following beneficial effects: (1) This invention uses a one-step method to modify Al with liquid metal to obtain a Ga-Al alloy, which destroys the dense oxide film on the surface of Al and improves its reactivity and heat release rate. Applying the Ga-Al alloy to thermite makes Al more resistant to oxidant reaction and improves combustion performance.

[0018] (2) The present invention adopts electrostatic spraying method, and the whole process is carried out at room temperature. It is a technology that can achieve low cost, simple, fast and continuous production. Furthermore, binders can be added to the thermite to improve its mechanical properties and mechanical properties.

[0019] (3) The nano-core-shell Ga-Al@NaIO4 thermite prepared by the present invention has a micro-morphology of spherical nano-thermite with uniform particle size distribution and good dispersibility. Both components (Ga-Al alloy core, NaIO4 and binder shell) are nanoscale, have close contact, and have good combustion and heat release performance.

[0020] (4) In this invention, nano-aluminum powder is dispersed and mixed with ammonium molybdate and tetrabutyl titanate in ethanol, and then dichloromethane is added as a pore-expanding agent. The mixture is freeze-dried in a low-temperature liquid nitrogen environment to obtain mixed particles with a dense porous structure. Finally, ammonium molybdate and tetrabutyl titanate are converted into molybdenum oxide and titanium dioxide by calcination, thus achieving the purpose of incorporating molybdenum oxide and titanium dioxide into nano-aluminum powder. At the same time, the doped nano-alumina has a denser porous structure and a larger specific surface area. After the doped nano-alumina and gallium indium tin alloy are used as the core of the nano-core-shell Ga-Al@NaIO4 thermite, the thermite combustion performance of the nano-core-shell Ga-Al@NaIO4 thermite is effectively improved, and the laser ignition threshold of the nano-core-shell Ga-Al@NaIO4 thermite is further reduced.

[0021] Other advantages, objectives and features of the present invention will be apparent in part from the following description, and in part from the understanding of those skilled in the art through study and practice of the invention. Attached Figure Description

[0022] Figure 1 This is a combustion process diagram of the nano-Ga-Al@NaIO4 aluminothermic agent in Example 1. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0024] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof. Example 1 This embodiment provides a method for preparing nano-core-shell Ga-Al@NaIO4 aluminothermic agent by electrostatic spraying, including the following steps: Step 1: Weigh 0.015g of liquid gallium-indium-tin alloy (Galinstan) and 0.485g of nano-aluminum powder, place them in 15mL of n-hexane, seal, sonicate for 60min, stir for 48h, and dry to obtain the modified Ga-Al alloy. The mass ratio of gallium, indium, and tin in the gallium-indium-tin alloy is 62:22:16; the content of the gallium-indium-tin alloy is 3wt.%~7wt.%. Step 2: Weigh 0.3g of NaIO4 and 0.025g of nitrocellulose (NC) and dissolve them in 4mL of a mixed solvent (where the volume ratio of acetone to diethyl ether is 3:1). Then weigh 0.025g of NC and 0.125g of Ga-Al alloy and add them to the above solution to form a suspension.

[0025] Step 3: Use a syringe to draw in the suspension, fix it on the electrostatic sprayer, and use an aluminum foil baffle to receive it. Connect the positive electrode to the needle of the syringe and the negative electrode to the aluminum foil baffle. Adjust the flow rate of the suspension to 0.05 mL / min, the negative pressure to -10 kV, and the positive pressure to 10 kV, so that the suspension forms a stable spray with a cone angle of 20~60° at the nozzle of the needle, thus obtaining the nano-core-shell Ga-Al@NaIO4 aluminothermic agent.

[0026] Figure 1 Images show the combustion process of the Ga-Al@NaIO4 aluminothermic agent prepared in this embodiment. The ignition delay time of the Ga-Al@NaIO4 aluminothermic agent is approximately 15 ms. It burns vigorously and uniformly, producing a bright flame surrounded by numerous sparks. The entire combustion process occurs between 15 and 200.5 ms, with a combustion time of approximately 185.5 ms, exhibiting a high combustion rate. This is because the aluminothermic agent prepared by electrostatic spraying contains nano-Al, increasing the number of surface-active atoms and groups, making it easier to activate and promoting the combustion of NaIO4.

[0027] Example 2 This embodiment provides a method for preparing nano-core-shell Ga-Al@NaIO4 aluminothermic agent by electrostatic spraying, including the following steps: Step 1: Weigh 0.025g of liquid gallium indium tin alloy (Galinstan) and 0.475g of nano-aluminum powder, place them in 15mL of n-hexane, seal them, sonicate for 60min, stir for 48h, and dry to obtain modified Ga-Al alloy.

[0028] Step 2: Weigh 0.3g of NaIO4 and 0.025g of nitrocellulose (NC) into 4mL of a mixed solvent of N,N-dimethylformamide and acetone (where the volume ratio of N,N-dimethylformamide and acetone is 4:1), and then weigh 0.125g of Ga-Al alloy and add it to the above solution to form a suspension.

[0029] Step 3: Draw the suspension into the syringe, fix it on the electrostatic sprayer, and receive it with an aluminum foil baffle. Connect the positive electrode to the needle of the syringe and the negative electrode to the aluminum foil baffle. Adjust the flow rate of the suspension to 0.05 mL / min, the negative pressure to -10 kV, and the positive pressure to 10 kV, so that the suspension forms a stable spray with a cone angle of 20~60° at the nozzle of the needle. The nano-core-shell Ga-Al@NaIO4 aluminothermic agent obtained in this embodiment is denoted as 1-Ga-Al@NaIO4 aluminothermic agent.

[0030] Example 3 This embodiment provides a method for preparing nano-core-shell Ga-Al@NaIO4 aluminothermic agent by electrostatic spraying, including the following steps: Step 1: Weigh 0.035g of liquid gallium indium tin alloy (Galinstan) and 0.465g of nano-aluminum powder, place them in 15mL of n-hexane, seal them, sonicate for 60min, stir for 48h, and dry to obtain modified Ga-Al alloy.

[0031] Step 2: Weigh 0.3g of NaIO4 and 0.025g of nitrocellulose (NC) into 4mL of a mixed solvent of N,N-dimethylformamide and acetone (where the volume ratio of N,N-dimethylformamide and acetone is 4:1), and then weigh 0.125g of Ga-Al alloy and add it to the above solution to form a suspension.

[0032] Step 3: Draw the suspension into the syringe, fix it on the electrostatic sprayer, and receive it with an aluminum foil baffle. Connect the positive electrode to the needle of the syringe and the negative electrode to the aluminum foil baffle. Adjust the flow rate of the suspension to 0.05 mL / min, the negative pressure to -10 kV, and the positive pressure to 10 kV, so that the suspension forms a stable spray with a cone angle of 20~60° at the nozzle of the needle. The nano-core-shell Ga-Al@NaIO4 aluminothermic agent prepared in this embodiment is designated as 2-Ga-Al@NaIO4 aluminothermic agent.

[0033] Example 4 This embodiment provides a method for preparing nano-core-shell Ga-Al@NaIO4 aluminothermic agent by electrostatic spraying. Compared with Example 1, in step one of this embodiment, before placing the liquid gallium indium tin alloy and nano-aluminum powder in the solvent for modification, the nano-aluminum powder is pretreated to obtain nano-aluminum powder doped with molybdenum oxide and titanium dioxide. The remaining processes in steps one, two, and three are the same as in Example 1. The method for pretreating the nano-aluminum powder includes: S1. Weigh 10g ammonium molybdate, 25mL tetrabutyl titanate and 80g nano aluminum powder and add them to 600mL ethanol. Stir and let stand. Then heat to 60℃ and add 20mL dichloromethane as a pore-expanding agent to the suspension. Stir evenly and keep warm for 3h. After cooling to room temperature, a mixed suspension is obtained. S2. The mixed suspension is spray-dried in a liquid nitrogen environment using a sprayer. The suspended particles are exposed to a low temperature environment and rapidly frozen to obtain a mixed powder with a dense pore structure. S3. The mixed powder after spray freeze-drying is subjected to high-temperature calcination at 800℃ for 4 hours, and then cooled to room temperature in the furnace to obtain nano-aluminum powder doped with molybdenum oxide and titanium dioxide.

[0034] Example 5 This embodiment provides a method for preparing nano-core-shell Ga-Al@NaIO4 aluminothermic agent by electrostatic spraying. Compared with Example 1, in step one of this embodiment, before placing the liquid gallium indium tin alloy and nano-aluminum powder in the solvent for modification, the nano-aluminum powder is pretreated to obtain nano-aluminum powder doped with molybdenum oxide and titanium dioxide. The subsequent process methods of steps one, two, and three are the same as in Example 1. The method for pretreating the nano-aluminum powder includes: S1. Weigh 2g of ammonium molybdate, 10mL of tetrabutyl titanate and 60g of nano aluminum powder and add them to 250mL of ethanol. Stir and let stand. Then heat to 40℃ and add 5mL of dichloromethane as a pore-expanding agent to the suspension. Stir evenly and keep warm for 1h. After cooling to room temperature, a mixed suspension is obtained. S2. The mixed suspension is spray-dried in a liquid nitrogen environment using a sprayer. The suspended particles are exposed to a low temperature environment and rapidly frozen to obtain a mixed powder with a dense pore structure. S3. The mixed powder after spray freeze-drying is subjected to high-temperature calcination at 600℃ for 1 hour, and then cooled to room temperature in the furnace to obtain nano-aluminum powder doped with molybdenum oxide and titanium dioxide.

[0035] Example 6 This embodiment provides a method for preparing nano-core-shell Ga-Al@NaIO4 aluminothermic agent by electrostatic spraying. Compared with Example 1, in step one of this embodiment, before placing the liquid gallium indium tin alloy and nano-aluminum powder in the solvent for modification, the nano-aluminum powder is pretreated to obtain nano-aluminum powder doped with molybdenum oxide and titanium dioxide. The remaining processes in steps one, two, and three are the same as in Example 1. The method for pretreating the nano-aluminum powder includes: S1. Weigh 6g of ammonium molybdate, 15mL of tetrabutyl titanate and 60g of nano aluminum powder and add them to 400mL of ethanol. Stir and let stand. Then heat to 60℃ and add dichloromethane as a pore-expanding agent to the suspension. Stir evenly and keep warm for 2h. After cooling to room temperature, a mixed suspension is obtained. S2. The mixed suspension is spray-dried in a liquid nitrogen environment using a sprayer. The suspended particles are exposed to a low temperature environment and rapidly frozen to obtain a mixed powder with a dense pore structure. S3. The mixed powder after spray freeze-drying is subjected to high-temperature calcination at 600℃ for 3 hours, and then cooled to room temperature in the furnace to obtain nano-aluminum powder doped with molybdenum oxide and titanium dioxide.

[0036] Comparative Example 1 This comparative example provides a method for preparing Ga-Al@NaIO4 aluminothermic agent by physical mixing, specifically including: Weigh 0.3g of NaIO4 and 0.025g of nitrocellulose, and weigh 0.125g of the Ga-Al alloy from Example 1. Place them together in 25mL of n-hexane, sonicate for 60min, stir for 2h, filter and dry. The Ga-Al@NaIO4 aluminothermic agent prepared in the comparative example is denoted as 3-Ga-Al@NaIO4 aluminothermic agent.

[0037] Comparative Example 2 This comparative example provides a method for preparing nano-core-shell Ga-Al@NaIO4 thermite using electrostatic spraying. Compared with Example 4, the pretreatment method for the nano-aluminum powder is as follows: S1. Add 10g ammonium molybdate and 80g nano aluminum powder to 600mL ethanol, stir and let stand, then heat to 60℃, add 20mL dichloromethane as a pore-expanding agent to the suspension, stir evenly and keep warm for 3h, and cool to room temperature to obtain a mixed suspension. S2. The mixed suspension is spray-dried in a liquid nitrogen environment using a sprayer. The suspended particles are exposed to a low temperature environment and rapidly frozen to obtain a mixed powder with a dense pore structure. S3. The spray-freeze-dried mixed powder is then subjected to high-temperature calcination at 800°C for 4 hours, followed by furnace cooling to room temperature to obtain nano-aluminum powder doped with molybdenum oxide and titanium dioxide. The remaining process methods are the same as in Example 4.

[0038] Comparative Example 3 This comparative example provides a method for preparing nano-core-shell Ga-Al@NaIO4 thermite using electrostatic spraying. Compared with Example 4, the pretreatment method for the nano-aluminum powder is as follows: S1. Add 25g ammonium molybdate and 80g nano aluminum powder to 600mL ethanol, stir and let stand, then heat to 60℃, add 20mL dichloromethane as a pore-expanding agent to the suspension, stir evenly and keep warm for 3h, and cool to room temperature to obtain a mixed suspension. S2. The mixed suspension is spray-dried in a liquid nitrogen environment using a sprayer. The suspended particles are exposed to a low temperature environment and rapidly frozen to obtain a mixed powder with a dense pore structure. S3. The spray-freeze-dried mixed powder is then subjected to high-temperature calcination at 800°C for 4 hours, followed by furnace cooling to room temperature to obtain nano-aluminum powder doped with molybdenum oxide and titanium dioxide. The remaining process methods are the same as in Example 4.

[0039] Comparative Example 4 This comparative example provides a method for preparing nano-core-shell Ga-Al@NaIO4 thermite using electrostatic spraying. Compared with Example 4, the pretreatment method for the nano-aluminum powder is as follows: S1. Weigh 10g of ammonium molybdate, 25mL of tetrabutyl titanate and 80g of nano-aluminum powder, mix them and calcine them at high temperature. The calcine temperature is 800℃ and the calcine time is 4h. Cool to room temperature with the furnace to obtain nano-aluminum powder doped with molybdenum oxide and titanium dioxide.

[0040] The table below shows the laser ignition thresholds of the Ga-Al@NaIO4 aluminothermic agents prepared in Examples 1-6 and Comparative Examples 1-4.

[0041] As can be seen from the table above, the nano-core-shell Ga-Al@NaIO4 aluminothermic agents prepared in Examples 1-6 have a lower laser ignition threshold than those in Comparative Examples 1-4. Furthermore, Examples 4-6 used nano-core-shell Ga-Al@NaIO4 aluminothermic agents prepared from modified pretreated nano-aluminum powder, which further reduced the laser ignition threshold of the nano-core-shell Ga-Al@NaIO4 aluminothermic agents.

[0042] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the invention will be readily apparent to those skilled in the art.

[0043] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for preparing nano-core-shell Ga-Al@NaIO4 aluminothermic agent by electrostatic spraying, characterized in that, Includes the following steps: Step 1: Take liquid gallium indium tin alloy and nano-aluminum powder doped with molybdenum oxide and titanium dioxide, place them in a solvent and seal them, then sonicate, stir and dry to obtain modified Ga-Al alloy; Step 2: Take NaIO4 and binder and place them in a mixed solvent to form a transparent and clear mixed solution; Step 3: Take the Ga-Al alloy obtained in Step 1 and add it to the mixed solution obtained in Step 2 to disperse and form a stable suspension; Step 4: Use a syringe to draw in the suspension, fix it on the electrostatic sprayer, and use an aluminum foil baffle to receive it. Connect the positive electrode to the needle of the syringe and the negative electrode to the aluminum foil baffle. Adjust the process parameters to make the suspension form a stable spray with a cone angle of 20~60° at the nozzle of the needle, and obtain the nano-core-shell Ga-Al@NaIO4 aluminothermic agent. In step one, before placing the liquid gallium indium tin alloy and nano-aluminum powder in a solvent for modification, the nano-aluminum powder is pretreated to obtain nano-aluminum powder doped with molybdenum oxide and titanium dioxide. The pretreatment method includes: S1. Weigh a certain amount of ammonium molybdate, tetrabutyl titanate, and nano-aluminum powder and add them to ethanol. Stir and let stand. Then heat to 40~60℃, add dichloromethane as a pore-expanding agent to the suspension, stir evenly and keep warm for 1~3h. After cooling to room temperature, a mixed suspension is obtained. The mass-volume ratio of ammonium molybdate, tetrabutyl titanate, nano-aluminum powder, ethanol, and dichloromethane is 2~10g:10~25mL:60~80g:250~1200mL:5~20mL. S2. The mixed suspension is spray-dried in a liquid nitrogen environment using a sprayer. The suspended particles are exposed to a low temperature environment and rapidly frozen to obtain a mixed powder with a dense pore structure. S3. The mixed powder after spray freeze-drying is subjected to high-temperature calcination at a temperature of 500~800℃ for 1~4h, and then cooled to room temperature in the furnace to obtain nano-aluminum powder doped with molybdenum oxide and titanium dioxide. The nano-core-shell Ga-Al@NaIO4 aluminothermic agent has a core-shell structure with a modified Ga-Al alloy core and NaIO4 and a binder as the outer shell. The particle size range of the nano-core-shell Ga-Al@NaIO4 aluminothermic agent is 100nm~500nm.

2. The method for preparing nano-core-shell Ga-Al@NaIO4 aluminothermic agent by electrostatic spraying according to claim 1, characterized in that, In step one, the mass ratio of gallium, indium, and tin in the gallium-indium-tin alloy is 62:22:16; the content of the gallium-indium-tin alloy is 3wt.%~7wt.%, which is the proportion of the gallium-indium-tin alloy in the total mass of the gallium-indium-tin alloy and the nano-aluminum powder.

3. The method for preparing nano-core-shell Ga-Al@NaIO4 aluminothermic agent by electrostatic spraying according to claim 1, characterized in that, In step one, the solvent is one of n-hexane, cyclohexane, n-heptane, ethyl acetate, and acetone. The mass-to-volume ratio of the total mass of gallium indium tin alloy and nano-aluminum powder to the solvent is 1g:15~30mL.

4. The method for preparing nano-core-shell Ga-Al@NaIO4 aluminothermic agent by electrostatic spraying according to claim 1, characterized in that, In step one, the ultrasonic time is greater than 30 minutes and the stirring time is greater than 36 hours.

5. The method for preparing nano-core-shell Ga-Al@NaIO4 aluminothermic agent by electrostatic spraying according to claim 1, characterized in that, In step two, the mixed solvent is a mixture of solvent I and solvent II, wherein solvent I is N,N-dimethylformamide; solvent II is one of acetone and ethyl acetate; and the volume ratio of solvent I to solvent II is 5:1 to 3:

1. The mass-to-volume ratio of NaIO4, total binder, and mixed solvent is 1g:2~4mL.

6. The method for preparing nano-core-shell Ga-Al@NaIO4 aluminothermic agent by electrostatic spraying according to claim 1, characterized in that, In step two, the adhesive is one of nitrocellulose, fluororubber, and hydroxyl-terminated azidoglycidyl ether.

7. The method for preparing nano-core-shell Ga-Al@NaIO4 aluminothermic agent by electrostatic spraying according to claim 1, characterized in that, The binder content accounts for 2 wt.%~5 wt.% of the total mass of Ga-Al alloy, NaIO4, and binder, the NaIO4 content is 60 wt.%~90 wt.%, and the Ga-Al alloy content is 10 wt.%~40 wt.%.

8. The method for preparing nano-core-shell Ga-Al@NaIO4 aluminothermic agent by electrostatic spraying according to claim 1, characterized in that, In step three, the dispersion method is two or more of magnetic stirring, mechanical stirring, and ultrasonic dispersion, and the dispersion time is 30-60 minutes.

9. The method for preparing nano-core-shell Ga-Al@NaIO4 aluminothermic agent by electrostatic spraying according to claim 1, characterized in that, In step four, the process parameters are adjusted as follows: flow rate 0.01~0.05mL / min, negative pressure controlled at -10kV~-12kV, and positive pressure controlled at 10~13kV.

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