High-heat-release three-dimensional porous nano thermite and confinement assembly preparation method thereof

Abstract

The invention discloses a high-heat-release three-dimensional porous nano thermite and a confinement assembly preparation method thereof, and belongs to the field of energetic material preparation. Hierarchical structure mesoporous CuO is constructed through biological templates (butterfly wings and lycopodium spores), and Al / PW-CuO and Al / LP-CuO are formed by confinement assembly of the hierarchical structure mesoporous CuO and nano aluminum powder. The unique ridge-shaped sheet and porous tetrahedral structure increases reaction sites and inhibits agglomeration of nano-aluminum. The method for preparing the thermite through a confinement assembly technology has the outstanding advantages of simple equipment, simplicity in operation, low cost, high safety, large-scale preparation and the like, the contact area between a combustion agent and an oxidizing agent can be effectively increased, the agglomeration phenomenon of particles is reduced, and the heat release and combustion performance of the thermite is enhanced.

Description

Technical Field

[0001] The invention belongs to the technical field of energetic material preparation, and in particular relates to a high-calorific-release three-dimensional porous nano-thermite. Background Art

[0002] Thermite is a composite energetic material with high energy density, high mass density and high safety performance, mainly composed of fuel (Al) and metal oxide (MO X ) under specific excitation conditions (e.g., sparks, heating, lasers), it can react rapidly and release enormous amounts of energy, generating temperatures exceeding 2000°C. This has broad application prospects in defense and economic development sectors, including aerospace, weapons and ammunition, transportation, and equipment manufacturing. As a dual-use energetic material, the development level of thermite has become an important indicator of a country's scientific and technological strength. In recent years, with the continuous advancement of micro-electromechanical systems (MEMS) technology, structural miniaturization and serial integration have become key trends in the development of modern energetic devices, placing higher demands on the performance of thermite. Therefore, the development of new, ultra-high-performance thermite has become a key research topic in the field of energetic materials, with significant implications for national defense and economic development.

[0003] Thermite reaction is a high temperature multiphase reaction, Al and MO X After diffusion and mass transfer, the reaction occurs at the interface. The rate of thermite reaction mainly depends on the Al and MO X The mass transfer efficiency between them. Traditional thermite is usually composed of micron-sized particles, Al and MO X The small contact area and long mass transfer distance between the two result in low heat release and a slow combustion rate. The Al2O3 oxide layer on the surface of current nano-aluminum powders hinders the thermal reaction, resulting in a large gap between the actual and theoretical heat release. Furthermore, the tendency for particles to agglomerate during processing and use is also a major contributor to this gap. Therefore, to inhibit particle agglomeration and improve mass transfer efficiency, a mesoporous metal oxide with a unique three-dimensional pore structure and spatially confined characteristics was designed and constructed. This increases the contact area between the reaction components, shortens the mass transfer distance, and improves the heat release performance of the aluminum powder.

[0004] The exothermic properties of thermite are closely related to its preparation method. Currently, the main methods for preparing thermite include physical mixing, magnetron sputtering, sol-gel, suppressed reaction ball milling, electrophoretic deposition, and self-assembly. Each of these methods has its own advantages and disadvantages, which to some extent limit its application and development. For example, physical mixing is simple to operate and low-cost, but physical mixing is prone to problems such as agglomeration and uneven distribution. While magnetron sputtering, performed in a vacuum environment, can effectively inhibit the oxidation of nanoaluminum, it is complex and expensive. The organic solvents used in the sol-gel method can introduce organic impurities into the energetic material, and the preparation cycle is long, hindering the rapid preparation of energetic materials. The elevated temperatures during the milling process in the suppressed reaction ball milling method pose significant safety risks. Conventional self-assembly techniques utilize chemical reactions or chemical adsorption to cause metals and metal oxides to spontaneously form specific spatial structures. Currently, thermite is loaded onto graphene oxide via surface-modified self-assembly. However, the loading efficiency and dispersion are poor, and the surface-modified graphene oxide also introduces impurities, affecting the thermite's exothermic properties. Therefore, developing a new method for the confined assembly of nanothermite is of great significance and practical application value for improving the dispersion of nanoaluminum, shortening mass transfer distances, and inhibiting the agglomeration of nanoaluminum. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-calorific-release three-dimensional porous nano-thermite and a confined assembly preparation method thereof. The method can enhance the heat release performance of the nano-thermite by constructing a mesoporous metal oxide pore structure with spatial confinement characteristics through a method based on structure regulation.

[0006] A high-calorific-release three-dimensional porous nano-thermite is constructed by constructing a mesoporous copper oxide with a hierarchical structure. The particle size of the nano-aluminum matches the pore structure of the mesopores. The nano-thermite is prepared by bio-templated confined assembly.

[0007] A method for preparing the aforementioned high-calorific-energy three-dimensional porous nano-thermite by confined assembly comprises the following steps: Step 1: Using biological materials as sacrificial templates, including butterfly wings (PW) and lycopodium spores (LP); Step 2: Immerse the pretreated template in a metal salt solution to adsorb Cu²⁺ ions. PW is soaked for 38 h. LP and Cu (NO₃)₂・3H₂O are mixed in a 1:1 mass ratio, and cetyltrimethylammonium bromide (CTAB) is added to assist dispersion. Step 3: The template adsorbed with metal ions is dried and then pyrolyzed in a high-temperature tube furnace. The PW template is calcined at a certain temperature for 2 h and cooled at a certain rate. The LP template is calcined at a certain temperature to form mesoporous CuO (PW-CuO and LP-CuO). Step 4: Mix the mesoporous CuO and the nano-aluminum powder in a stoichiometric ratio of Φ=0.5-2.5, add anhydrous ethanol, stir magnetically for a certain period of time, and vacuum dry to obtain the nano-thermite.

[0008] Furthermore, in step 1, the biological template is a natural hierarchical structure material, PW has a ridged lamellar microstructure, and LP has a radial tetrahedral porous structure.

[0009] Furthermore, the metal salt solution stirred in step 2 is a copper nitrate trihydrate (Cu (NO3)2·3H2O) solution.

[0010] Furthermore, in step 3, the pyrolysis temperature of the high-temperature tube furnace is 500° C. (PW template) and 550° C. (LP template final temperature), and the cooling rate is 5° C. / min.

[0011] Furthermore, in step 4, the mixed solvent is anhydrous ethanol, the magnetic stirring time is 3 h, the vacuum drying temperature is 50° C., and the drying time is 12 h.

[0012] Furthermore, the contact area between mesoporous CuO and nano-aluminum is significantly improved through the hierarchical structure, with the heat release of Al / PW-CuO ranging from 884.75 to 2278.00 J / g and that of Al / LP-CuO ranging from 501.7 to 1969.08 J / g.

[0013] Furthermore, when Φ = 1.5, the Al / PW-CuO reaction is vigorous and the energy release efficiency is high.

[0014] Beneficial effects: Constructing a mesoporous metal oxide with a unique three-dimensional pore structure and spatial confinement characteristics, which can not only improve the dispersibility of nano-aluminum, increase the contact area with the metal oxide, shorten the mass transfer distance, but also reduce the agglomeration of particles and improve the heat release performance of the nano-thermite; through structural regulation to prepare a high-heat release three-dimensional porous nano-thermite, nano-aluminum can enter the interior of the mesoporous metal oxide, which can increase the contact area between the two and improve the heat release efficiency. It has the outstanding advantages of simple equipment, simple operation, low cost and high safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a flow chart for preparing the three-dimensional porous nano-thermite in the embodiment; Figure 2 EDS images of (a, b) Al / pw-cuo and (c, d) Al / lp-cuo nano-thermites in the examples; Figure 3 This is the exothermic curve of nano-thermite prepared by conventional self-assembly method; Figure 4The DSC curves of (a) Al / pw-cuo, (b) Al / lp-cuo, (c) the total heat release of Al / pw-cuo, and (d) the total heat release of Al / lp-cuo in the examples are shown. DETAILED DESCRIPTION

[0016] The following is a clear and complete description of the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. Example 1

[0017] Nano-thermite was prepared by the following steps: Step 1: Take butterfly wings and soak them in ethanol for 1 h, 1.0 mol / L hydrochloric acid for 2 h, and 7% NaOH for 2 h, rinse with deionized water and ethanol until neutral, and dry for later use; Step 2: Immerse the pretreated PW in a 0.8 g / mL Cu (NO3)2·3H2O solution for 38 h to adsorb Cu²⁺ ions. Remove and dry at 50°C for 12 h. Step 3: PW adsorbed with Cu²⁺ was placed in a high-temperature tube furnace, calcined at 500°C for 2 h, and cooled at a rate of 5°C / min to obtain ridged flake PW-CuO. Step 4: PW-CuO and 100 nm nano-aluminum powder (Φ=1.5) were added to anhydrous ethanol and magnetically stirred for 3 h, and then transferred to a vacuum drying oven at 50°C for 12 h to obtain Al / PW-CuO nano-thermite; like Figure 4 As shown in the figure, DSC measurement shows that the heat released is 2278.00 J / g when Φ=1.5. Example 2

[0018] Nano-thermite was prepared by the following steps: Step 1: Take Lycopodium spores (LP), wash them with ethanol solution, centrifuge (10,000 rpm, 5 min), and dry them for later use; Step 2: LP and Cu (NO3)2·3H2O were mixed in a 1:1 mass ratio, 2 g of CTAB was added (in two additions with an interval of 15 min), anhydrous ethanol was added and magnetically stirred for 4 h (25 °C), and dried at 50 °C for 12 h; Step 3: Place the dried LP-Cu²⁺ composite into a high-temperature tube furnace and heat it at 100°C, 200°C, and 550°C for 2 h each. After cooling, radial tetrahedral porous LP-CuO is obtained. Step 4: LP-CuO and 100 nm nano-aluminum powder (Φ=1.5) were added to anhydrous ethanol and magnetically stirred for 3 h, and then vacuum dried (50°C, 12 h) to prepare Al / LP-CuO nano-thermite; like Figure 4 As shown in the figure, DSC measurement shows that the heat released is 1969.08 J / g when Φ=1.5. Example 3

[0019] Nano-thermite was prepared by the following steps: Step 1: Take butterfly wings and soak them in ethanol for 1 h, 1.0 mol / L hydrochloric acid for 2 h, and 7% NaOH for 2 h, rinse with deionized water and ethanol until neutral, and dry for later use; Step 2: Immerse the pretreated PW in a 0.8 g / mL Cu (NO3)2·3H2O solution for 38 h to adsorb Cu²⁺ ions. Remove and dry at 50°C for 12 h. Step 3: PW adsorbed with Cu²⁺ was placed in a high-temperature tube furnace, calcined at 500°C for 2 h, and cooled at a rate of 5°C / min to obtain ridged flake PW-CuO. Step 4: PW-CuO and 100 nm nano-aluminum powder (Φ=2.0) were added with anhydrous ethanol and magnetically stirred for 3 h, and then transferred to a vacuum drying oven at 50 °C and dried for 12 h to obtain Al / PW-CuO nano-thermite.

[0020] like Figure 4 As shown in the figure, DSC measurement shows that the heat released is 2193.11 J / g when Φ=2.0.

[0021] Comparative Example 1 Preparation of nano-thermite by conventional self-assembly method: Step 1: A certain amount of poly (4-vinyl pyridine) and CuO with a particle size of 400 nm were dispersed in isopropanol in sequence and magnetically stirred at room temperature for 4 h. Then, isopropanol was used as the solvent and centrifuged (8000 rpm, 10 min) to remove the unencapsulated poly (4-vinyl pyridine). Finally, the mixture was centrifuged at 80 o C and vacuum dried for 2 h; Step 2: The product obtained in step 1 and the nanoparticles were sequentially added to isopropanol, magnetically stirred for 2 h, and then transferred to a vacuum drying oven and dried at 80 °C for 2 h to obtain nano-thermite.

[0022] like Figure 3 As shown, DSC measurement shows that the initial reaction temperature of the nano-thermite prepared in Comparative Example 1 is 369° C. and the heat release is 1250 J / g.

Claims

1. A high heat release three-dimensional porous nano-thermite, characterized by: A mesoporous copper oxide with a hierarchical structure was constructed, the particle size of nanoaluminum matched the pore structure of the mesopores, and nano-thermite was prepared through bio-templated confined assembly.

2. The method for preparing the confined assembly of the high-calorific-release three-dimensional porous nano-thermite according to claim 1, comprising the following steps: Step 1: using biological materials as sacrificial templates, including butterfly wings and lycopodium spores; Step 2: Immerse the pretreated template in a metal salt solution to adsorb Cu²⁺ ions. PW is soaked for 38 h. LP and Cu(NO₃)₂・3H₂O are mixed in a 1:1 mass ratio, and cetyltrimethylammonium bromide is added to assist in dispersion. Step 3: The template adsorbing metal ions is dried and then pyrolyzed in a high-temperature tube furnace. The PW template is calcined at a certain temperature for 2 hours and cooled at a certain rate. The LP template is calcined at a certain temperature to form mesoporous copper oxide. Step 4: Mix the mesoporous copper oxide and the nano-aluminum powder in a stoichiometric ratio of Φ=0.5-2.5, add anhydrous ethanol, stir magnetically for a certain period of time, and vacuum dry to obtain the nano-thermite.

3. The method according to claim 2, characterized in that In step 1, the biotemplate is a natural hierarchical structure material, PW has a ridged lamellar microstructure, and LP has a radial tetrahedral porous structure.

4. The method according to claim 2, characterized in that The metal salt solution stirred in step 2 is a copper nitrate trihydrate solution.

5. The method according to claim 2, characterized in that In step 3, the pyrolysis temperature of the high-temperature tube furnace is 500° C.-550° C., and the cooling rate is 5° C. / min.

6. The method according to claim 2, characterized in that In step 4, the mixed solvent is anhydrous ethanol, the magnetic stirring time is 3 h, the vacuum drying temperature is 50° C., and the drying time is 12 h.

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