Oxidizer-assembled high-sphericity boron-based composite energetic materials and methods of making

Abstract

The application provides an oxidant-assembled boron-based composite energetic material with high sphericity and a preparation method, comprising a boron matrix, and an energetic oxidant assembled on the boron matrix; the boron matrix is boron powder, monovalent modified boron powder or divalent modified boron powder; the monovalent modified boron powder is obtained by depositing metal oxide on the surface of boron powder by using an atomic layer deposition method; the divalent modified boron powder is obtained by depositing metal oxide and metal molybdenum on the surface of boron powder by using an atomic layer deposition method; the energetic oxidant is ammonium perchlorate, ammonium nitrate or potassium perchlorate; and the boron-based composite energetic material has a spherical particle shape. The composite energetic material prepared by using a spray drying technology has a short laser ignition delay time, excellent ignition and combustion performance, and has a very good application prospect. The application can simultaneously solve the problems of limited boron powder surface activity, nanoscale uniform composite of boron powder and energetic oxidant, and integrated solution of optimization of spheroidization morphology and improvement of process performance.

Description

Technical Field

[0001] This invention belongs to the field of energetic materials technology, and relates to boron-based energetic materials, specifically to a high sphericity boron-based composite energetic material assembled with an oxidant and its preparation method. Background Technology

[0002] Boron possesses extremely high calorific value (approximately 58.5 kJ / g) and volumetric calorific value, making it considered one of the most promising metallic fuels in the fields of solid propellants and explosives. Theoretically, applying boron powder to fuel-rich propellants or high-energy explosives could significantly enhance the range and destructive power of weapon systems. However, in practical applications, the energy release of nano- or micron-sized boron powder faces multiple physical and chemical obstacles, mainly in the following three aspects:

[0003] First, the surface of boron powder is usually covered with a natural oxide layer (B2O3), which has a boiling point as high as 1860℃. In the initial stage of ignition, the liquid B2O3 will coat the boron particles, hindering the diffusion of oxygen into the interior, making it difficult for the boron powder to burn completely and resulting in low energy release efficiency.

[0004] Furthermore, the heat and mass transfer processes between components in traditional energetic materials are limited. Traditional energetic material preparation typically employs simple physical mixing methods. Because boron nanopowder readily agglomerates and has only limited point contact with energetic oxidant particles such as ammonium perchlorate (AP), the mass transfer distance between reactants is excessively long. During rapid combustion, the oxygen generated by the decomposition of the energetic oxidant cannot be supplied to the boron powder in a timely manner, limiting the chemical reaction rate.

[0005] Furthermore, boron powder exhibits poor morphology, processability, and flowability. Amorphous or irregularly shaped boron powder has a large specific surface area and high surface energy, resulting in strong hygroscopicity, high viscosity, and poor flowability in propellant slurries. This not only deteriorates processing performance but also limits the high-solids-content loading of boron powder in formulations.

[0006] To address the aforementioned problems, existing technologies mostly employ a single approach for improvement.

[0007] Energetic materials formed by combining boron with energetic oxidizers are a class of metastable energetic systems prepared by combining high-energy fuel boron powder with strong energetic oxidizers. These materials combine the high volumetric calorific value of boron with the dual advantages of energetic oxidizers—high oxygen content and excellent decomposition characteristics—showing significant application potential in defense and industrial fields such as propellants, explosives, and ignition agents. However, due to the constraints of the aforementioned oxide layer, the ignition process of boron particles exhibits a relatively long "ignition delay period," during which heating, melting, and ultimately breaking through the surface oxide layer barrier occur. This directly leads to a significant increase in the ignition delay time of boron / energetic oxidizer composite materials, making it difficult to meet the stringent requirements of applications such as igniters and initiating elements that demand rapid response.

[0008] While surface modification through pickling or other technical means can improve the ignition performance of boron powder, its degree of integration with energetic oxidants in subsequent applications cannot be fundamentally improved.

[0009] While physical mixing of boron powder or modified boron powder with energetic oxidants can shorten the diffusion distance, it fails to improve the powder's flowability and packing performance. To overcome these shortcomings, an integrated preparation technology that can simultaneously achieve surface activity regulation, precise component compounding, and morphology optimization is urgently needed. Summary of the Invention

[0010] To address the shortcomings of existing technologies, the present invention aims to provide an oxidant-assembled high-sphericity boron-based composite energetic material and its preparation method, thereby solving the technical problems in existing oxidant-assembled high-sphericity boron-based composite energetic materials that are difficult to simultaneously achieve the surface activity of boron powder, the nanoscale composite of boron powder and energetic oxidant, and the spherical morphology.

[0011] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0012] An oxidant-assembled high-sphericity boron-based composite energetic material includes a boron matrix on which an energetic oxidant is assembled.

[0013] The boron matrix is ​​boron powder, mono-modified boron powder, or binary modified boron powder.

[0014] The mono-modified boron powder is prepared by depositing metal oxides on the surface of boron powder using atomic layer deposition (ALD); the binary modified boron powder is prepared by depositing metal oxides and molybdenum metal on the surface of boron powder using ALD.

[0015] The energetic oxidant is ammonium perchlorate (AP, NH4ClO4), ammonium nitrate (AN, NH4NO3) or potassium perchlorate (PP, KClO4).

[0016] The morphology of the boron-based composite energetic material is rough-surfaced spherical particles.

[0017] The present invention also has the following technical features.

[0018] Preferably, the diameter of the spherical particles is 2 to 25 μm.

[0019] Preferably, the energetic oxidant accounts for 10 wt% to 20 wt% of the mass percentage of the high sphericity boron-based composite energetic material assembled with the oxidant.

[0020] More preferably, the energetic oxidant accounts for 16.7 wt% of the mass of the high sphericity boron-based composite energetic material assembled with the oxidant.

[0021] Preferably, the metal oxide is TiO2.

[0022] Preferably, the boron matrix is ​​boron powder B, mono-modified boron powder B@TiO2, or binary modified boron powder B@TiO2@Mo.

[0023] This invention also protects a method for preparing a boron-based composite energetic material with high sphericity assembled by an oxidant, characterized in that the method uses a spray drying method to prepare the boron-based composite energetic material with high sphericity assembled by an oxidant.

[0024] The method includes the following steps.

[0025] Step 1: Add water to the energetic oxidant and stir with a magnetic stirrer until the energetic oxidant is completely dissolved.

[0026] Step 2: Add the boron matrix to the solution prepared in Step 1 and stir continuously for 30 minutes to obtain a liquid. Then, continuously sonicate the liquid and insert the spray drying feed pipe into the liquid.

[0027] Step 3: The atmosphere of the spray dryer is high-purity nitrogen. Set the reaction temperature, feed rate and spray pressure of the spray dryer. After the reaction temperature of the spray dryer reaches the preset value, start the peristaltic pump.

[0028] Step 4: After the liquid material has completely entered the spray dryer, turn off the peristaltic pump and the spray dryer. After the temperature drops to room temperature, open the material collector and collect the sample to obtain the high sphericity boron-based composite energetic material assembled with oxidant.

[0029] Preferably, in step 2, the material concentration of the liquid is 6 wt% to 48 wt%.

[0030] Preferably, in step 3, the reaction temperature is 120°C to 180°C, the feed rate is 5 r / min to 15 r / min, and the spray pressure is 0.05 MPa to 0.2 MPa.

[0031] Compared with the prior art, the present invention has the following technical effects.

[0032] (I) This invention employs spray drying technology to prepare a nano-boron-based metastable composite energetic material with finely assembled energetic oxidant, using boron powder, mono-modified boron powder, or binary-modified boron powder and an energetic oxidant as raw materials. This binary composite energetic material exhibits a short laser ignition delay time, excellent ignition and combustion performance, and shows great application potential. This invention provides an integrated solution that simultaneously addresses the limitations of boron powder surface activity, the uniform nanoscale composite of boron powder and energetic oxidant, and the optimization of spherical morphology to improve process performance.

[0033] (II) In this invention, the energetic oxidant and the modified layer (@TiO2 and @Mo) can play a synergistic optimization role in improving the calorific value of boron powder. The Mo modified layer (@Mo) in the modified layer has a more significant effect on improving the calorific value of boron-based nanocomposite energetic materials.

[0034] The synergistic optimization effect is specifically manifested in the following ways: adding a Mo-modified layer is a highly efficient catalytic promotion strategy. The Mo-modified layer can significantly reduce the high-temperature decomposition temperature of energetic oxidants and promote the formation of intermediate products with stronger oxidizing activity, such as HClO4 and ClO2. This provides a more active reaction environment and a more sufficient amount of gas-phase energetic oxidants for the early oxidation of boron, thereby significantly shortening the ignition delay time of the entire composite system. By accelerating the ignition process and optimizing the combustion reaction path, the introduction of the Mo-modified layer can ensure that more boron particles are fully oxidized in a shorter time, which not only improves the energy release rate but also enhances the combustion efficiency of boron, ultimately significantly strengthening the actual energy release performance of the composite material.

[0035] (III) The oxidation peak temperature of the metastable composite energetic material of the present invention is 570°C to 524°C, which is significantly lower than that of boron powder or surface-modified boron powder, and is reduced by up to 153°C; the ignition delay time of the metastable composite energetic material is 34.4ms to 54.4ms, which is significantly shorter than that of boron powder, thereby improving the reactivity of boron powder; the calorific value of the metastable composite energetic material is 24.1kJ / mol to 32.6kJ / mol.

[0036] (IV) The three boron-based / energetic oxidant metastable composite energetic materials prepared by this invention, namely B@AP, B@TiO2@AP, and B@TiO2@Mo@AP, exhibit significantly lower exothermic peak temperatures than boron powder. This is because AP can decompose at lower temperatures under the action of TiO2 to generate intermediate products with stronger oxidizing activity, such as HClO4 and ClO2, providing a more active reaction environment and more sufficient gas-phase energetic oxidant for the early oxidation of boron, thereby significantly reducing the exothermic oxidation temperature of boron powder. This also indicates that AP and TiO2 modified layers have a very obvious synergistic effect in reducing the oxidation temperature of boron powder. The composite modified layer promotes the oxidation process of boron in synergy with the gas-phase oxidation effect of AP decomposition through the composite mechanism of oxygen vacancies and catalytic reaction, resulting in a significant reduction in the oxidation reaction temperature of boron and improved ignition and combustion performance.

[0037] (V) The three boron-based / energetic oxidant metastable composite energetic materials prepared by this invention, namely B@AP, B@TiO2@AP, and B@TiO2@Mo@AP, have shorter ignition delay times. In contrast, B@HTPB has an ignition delay time of 66.16 ms, which actually prolongs the ignition delay time. AP works synergistically with the mono-modified layer and the composite modified layer, significantly reducing the ignition delay time of boron and enhancing its reactivity.

[0038] (VI) The three boron-based / energetic oxidant metastable composite energetic materials prepared by this invention, namely B@AP, B@TiO2@AP, and B@TiO2@Mo@AP, all showed improved calorific values ​​compared to the raw boron powder. However, the calorific value of B@HTPB was significantly reduced. Therefore, the synergistic effect of AP and the modified layer on improving the calorific value of boron is significant, with the calorific value of the nanocomposite energetic material containing the Mo modified layer showing a particularly significant improvement.

[0039] (VII) The preparation method of the present invention is simple, efficient, reproducible and low cost; the preparation method adopted in the present invention has high control precision and is easy to industrialize, showing good application prospects in the field of high-energy solid fuel modification. Attached Figure Description

[0040] Figure 1 This is a SEM image of B@AP.

[0041] Figure 2 The images are SEM elemental distribution mapping images for B@AP, where B1 is a combined image of the electron image and the measured elements, and B2-B4 are elemental distribution images for B, Cl, and O, respectively.

[0042] Figure 3 The images are SEM and mapping images of B@TiO2@AP, where C1 and C2 are SEM images, C3 is a combined image of the electron image and the measured elements, and C4-C8 are the distribution images of B, Cl, Ti, N, and O elements, respectively.

[0043] Figure 4 The images are SEM images and elemental distribution mapping images of B@TiO2@Mo@AP, where D1 and D2 are SEM images, D3 is a combined image of the electron image and the measured elements, and D4-D8 are elemental distribution images of B, Cl, Mo, Ti, and O, respectively.

[0044] Figure 5 The DSC data plots are for B, B@AP, B@TiO2@AP, B@TiO2@Mo@AP, and B@TiO2. Where a represents B, b represents B@AP, c represents B@TiO2 from Comparative Example 2, d represents B@TiO2@AP, and e represents B@TiO2@Mo@AP.

[0045] Figure 6 This graph shows the laser ignition delay time data for B, B@AP, B@TiO2@AP, B@TiO2@Mo@AP, and B@TiO2. Where a1 represents B, a2 represents B@AP, a3 represents B@TiO2@AP, a4 represents B@TiO2@Mo@AP, a5 represents B@TiO2, a6 represents B@HTPB, a7 represents B / AP (impregnation method), and a8 represents B / AP (ball milling method).

[0046] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0047] It should be noted that, unless otherwise specified, all materials and devices used in this invention are those known in the art.

[0048] In this invention, boron powder can also be referred to as boron particles or boron fuel; all three are the same concept. The boron powder is amorphous boron fuel and / or crystalline boron fuel, with a particle size distribution ranging from micrometers to nanometers. Preferably, the particle size of the boron powder is 100 nm to 5 μm.

[0049] In this invention, the boron powder is boron raw material that has not been modified by atomic layer deposition. The unary modified boron powder is boron powder with a modification layer such as B@TiO2 deposited on its surface by atomic layer deposition technology. The binary modified boron powder is boron powder with two modification layers such as B@TiO2@Mo deposited on its surface by atomic layer deposition technology.

[0050] The oxidant-assembled high-sphericity boron-based composite energetic material of the present invention is used as a boron-based fuel in the field of explosives.

[0051] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0052] Example 1: This embodiment provides a method for preparing a boron-based composite energetic material with high sphericity assembled with an oxidant, which includes the following steps.

[0053] Step 1: Weigh 1g of NH4ClO4 and pour it into an Erlenmeyer flask. Measure 25ml of deionized water using a graduated cylinder and pour it into the Erlenmeyer flask. Add a magnetic stir bar and stir until the NH4ClO4 is completely dissolved.

[0054] Step 2: Weigh 5g of boron powder and pour it into the solution prepared in Step 1 and stir continuously for 30 minutes to obtain a liquid. Then, continuously sonicate the liquid and insert the spray drying feed tube into the liquid.

[0055] Step 3: Set the spray dryer parameters to 180℃ reaction temperature, 15r / min feed rate, and 0.1MPa spray pressure. After the reaction temperature reaches the preset value, turn on the peristaltic pump.

[0056] Step 4: After the liquid material has completely entered the spray dryer, turn off the peristaltic pump and the spray dryer. After the temperature drops to room temperature, open the material collector and collect the sample to obtain the high sphericity boron-based composite energetic material B@AP assembled with oxidant.

[0057] In the B@AP material obtained in this embodiment, the AP content is 16.7%wt.

[0058] Figure 1 For SEM images of B@AP, from Figure 1 As can be seen from the low-magnification electron microscope, the sample morphology is a rough-surfaced spherical particle with a size of 2 to 25 μm. Further magnification shows that this type of spherical particle is composed of many irregular small particles.

[0059] Figure 2 Mapping images of element distribution in B@AP SEM, from Figure 2 As can be seen, the distribution areas and trends of B, N, Cl, and O elements are almost identical, which also indicates that the components of the B@AP material prepared by spray drying technology are uniformly distributed.

[0060] Example 2: This embodiment provides a method for preparing a boron-based composite energetic material with high sphericity assembled with an oxidant, which includes the following steps.

[0061] Step 1: Prepare B@TiO2 mono-modified boron powder using atomic layer deposition technology.

[0062] Step 1.1: Spread boron powder evenly on the sample stage, then place the sample stage in the reaction chamber of the atomic layer deposition equipment. Use a mechanical pump to evacuate the reaction chamber to below 20 Pa. Set the temperature of the ALD reaction chamber to 230℃, set the temperature of the niobium ethanol storage tank to 120℃, and set the carrier gas flow rate to 105 ml / min.

[0063] Step 1.2: Tetraisopropoxide vapor is introduced into the reaction chamber by bubbling with carrier gas, so that the tetraisopropoxide vapor molecules are adsorbed on the surface of boron powder. The introduction time is 60s. Then, the tetraisopropoxide vapor physically adsorbed on the sample surface is blown off the sample surface for 60s.

[0064] Step 1.3: Inject hydrogen peroxide vapor into the reaction chamber to allow the hydrogen peroxide molecules to fully react with the tetraisopropoxide titanium molecules chemically adsorbed on the surface of the boron powder. The infusion time is 60s. Then, the excess hydrogen peroxide molecules and byproducts are blown away from the sample surface for 60s.

[0065] Steps 1.4 and 1.2 to 1.3 constitute one cycle of TiO2 deposition. Repeating steps 1.2 to 1.3 can control the number of TiO2 deposition cycles to 10 cycles, thus obtaining B@TiO2 mono-modified boron powder.

[0066] Step 2: Weigh 1g of NH4ClO4 and pour it into an Erlenmeyer flask. Measure 25ml of deionized water using a graduated cylinder and pour it into the Erlenmeyer flask. Add a magnetic stir bar and stir until completely dissolved.

[0067] Step 3: Weigh 5g of B@TiO2 mono-modified boron powder and pour it into the solution prepared in step 2. Stir continuously for 30 minutes to obtain a liquid. Then, continuously sonicate the liquid and insert the spray drying feed tube into the liquid.

[0068] Step 4: Set the spray dryer parameters to 180℃ reaction temperature, 15r / min feed rate, and 0.1MPa spray pressure. After the reaction temperature reaches the preset value, turn on the peristaltic pump.

[0069] Step 5: After the liquid material has completely entered the spray dryer, turn off the peristaltic pump and the spray dryer. After the temperature drops to room temperature, open the material collector and collect the sample to obtain the high sphericity boron-based composite energetic material B@TiO2@AP assembled with oxidant.

[0070] In the B@TiO2@AP material obtained in this embodiment, the AP content is 16.7 wt%, and the TiO2 deposition cycle number is 10 cycles.

[0071] Figure 3 The images show SEM and mapping of B@TiO2@AP. The SEM images reveal that the sample morphology consists of numerous irregular small particles with rough, near-spherical surfaces, ranging in size from 2 to 25 μm. The elemental distribution maps show that the distribution areas and trends of B, Cl, Ti, N, and O are almost identical, indicating that the components of the B@TiO2@AP material prepared using spray drying technology are uniformly distributed.

[0072] Example 3: This embodiment provides a method for preparing a boron-based composite energetic material with high sphericity assembled with an oxidant, which includes the following steps.

[0073] Step 1: Prepare B@TiO2@Mo binary modified boron powder using atomic layer deposition technology.

[0074] Step 1.1: Spread boron powder evenly on the sample stage, then place the sample stage in the reaction chamber of the atomic layer deposition equipment. Use a mechanical pump to evacuate the reaction chamber to below 20 Pa. Set the temperature of the ALD reaction chamber to 150℃, set the temperature of the tetraisopropoxide titanium storage tank to 120℃, and set the carrier gas flow rate to 130 ml / min.

[0075] Step 1.2: Tetraisopropoxide vapor is introduced into the reaction chamber by bubbling with carrier gas, so that the tetraisopropoxide vapor molecules are adsorbed on the surface of boron powder. The introduction time is 60s. Then, the tetraisopropoxide vapor physically adsorbed on the sample surface is blown off the sample surface for 60s.

[0076] Step 1.3: Inject hydrogen peroxide vapor into the reaction chamber to allow the hydrogen peroxide molecules to fully react with the tetraisopropoxide titanium molecules chemically adsorbed on the surface of the boron powder. The infusion time is 60s. Then, the excess hydrogen peroxide molecules and byproducts are blown away from the sample surface for 60s.

[0077] Steps 1.4, 1.2 to 1.3 constitute one cycle of TiO2 deposition. Repeating steps 1.2 to 1.3 can control the number of TiO2 deposition cycles to 10 cycles.

[0078] Step 1.5: Si₂H₆ is injected into the adjustable precursor storage container. The carrier gas and the pneumatic valve of the mechanical pump are closed to bring the system to a near-static state. Then, the precursor in the storage container is injected into the reaction chamber for 30 seconds to allow for saturation adsorption of the precursor on the boron particles. After sufficient adsorption, the pneumatic valve of the mechanical pump is opened to remove excess precursor or physically adsorbed precursor from the reaction chamber for 25 seconds. Then, the carrier gas is started for purging for 25 seconds.

[0079] Step 1.6: MoF6 is injected into an adjustable precursor storage container, which allows for precise control of the amount of precursor entering the system. The pneumatic valves of the carrier gas and mechanical pump are closed, bringing the system to a near-static state. The precursor from the storage container is then injected into the reaction chamber over 30 seconds, allowing MoF6 to fully react with Si2H6 adsorbed on the boron particles. After the reaction is complete, the pneumatic valve of the mechanical pump is opened to remove excess precursor or byproducts from the reaction chamber over 25 seconds. Then, the carrier gas is used for purging for 25 seconds. The carrier gas is either high-purity argon or high-purity nitrogen.

[0080] Steps 1.7, 1.5, and 1.6 constitute one cycle of elemental Mo deposition. Steps 1.2 and 1.3 are repeated to control the number of deposition cycles of elemental Mo on the boron particles to be 5 cycles. This yields B@TiO2@Mo binary modified boron powder.

[0081] Step 2: Weigh 1g of NH4ClO4 and pour it into an Erlenmeyer flask. Measure 25ml of deionized water using a graduated cylinder and pour it into the Erlenmeyer flask. Add a magnetic stir bar and stir until completely dissolved.

[0082] Step 3: Weigh 5g of B@Nb2O5@Mo binary modified boron powder and pour it into the solution prepared in Step 2. Stir continuously for 30 minutes to obtain a liquid. Then, continuously sonicate the liquid and insert the spray drying feed tube into the liquid.

[0083] Step 4: Set the spray dryer parameters to 180℃ reaction temperature, 15r / min feed rate, and 0.1MPa spray pressure. After the reaction temperature reaches the preset value, turn on the peristaltic pump.

[0084] Step 5: After the liquid material has completely entered the spray dryer, turn off the peristaltic pump and the spray dryer. After the temperature drops to room temperature, open the material collector and collect the sample to obtain the high sphericity boron-based composite energetic material B@Nb2O5@Mo@AP assembled with oxidant.

[0085] In the B@TiO2@Mo@AP material obtained in this embodiment, the AP content is 16.7 wt%, the number of Mo deposition cycles is 5, and the number of TiO2 deposition cycles is 10.

[0086] Figure 4 SEM images and elemental mapping images of B@TiO2@Mo@AP are shown. The SEM images reveal that the sample morphology consists of numerous irregularly shaped, rough-surfaced, near-spherical particles, ranging in size from 2 to 25 μm. The elemental mapping images show that the distribution areas and trends of B, Cl, Mo, Ti, and O are almost identical, indicating that the components of the B@TiO2@Mo@AP material prepared using spray drying technology are uniformly distributed.

[0087] Example 4: This embodiment provides a method for preparing a boron-based composite energetic material with high sphericity assembled with an oxidant. The method is basically the same as that in Example 1, except that NH4ClO4 in Example 1 is replaced with an equal amount of NH4NO3.

[0088] In the B@AN material obtained in this embodiment, the AN content is 16.7 wt%.

[0089] Example 5: This embodiment provides a method for preparing a boron-based composite energetic material with high sphericity assembled with an oxidant. The method is basically the same as that in Example 1, except that NH4ClO4 in Example 2 is replaced with an equal amount of NH4NO3.

[0090] In the B@TiO2@AN material obtained in this embodiment, the AN content is 16.7 wt%. The number of TiO2 deposition cycles is 10 cycles.

[0091] Example 6: This embodiment provides a method for preparing a boron-based composite energetic material with high sphericity assembled with an oxidant. The method is basically the same as that in Example 1, except that NH4ClO4 in Example 3 is replaced with an equal amount of NH4NO3.

[0092] In the B@TiO2@Mo@AN material obtained in this embodiment, the AN content is 16.7 wt%. The deposition cycle number of TiO2 is 10 cycles, and the deposition cycle number of Mo is 5 cycles.

[0093] Example 7: This embodiment provides a method for preparing a boron-based composite energetic material with high sphericity assembled with an oxidant. The method is basically the same as that in Example 1, except that NH4ClO4 in Example 1 is replaced with an equal amount of KClO4.

[0094] In the B@PP material obtained in this embodiment, the PP content is 16.7 wt%.

[0095] Example 8: This embodiment provides a method for preparing a boron-based composite energetic material with high sphericity assembled with an oxidant. The method is basically the same as that in Example 1, except that NH4ClO4 in Example 2 is replaced with an equal amount of KClO4.

[0096] In the B@TiO2@PP material obtained in this embodiment, the PP content is 16.7 wt%. The number of TiO2 deposition cycles is 10 cycles.

[0097] Example 9: This embodiment provides a method for preparing a boron-based composite energetic material with high sphericity assembled with an oxidant. The method is basically the same as that in Example 1, except that NH4ClO4 in Example 3 is replaced with an equal amount of KClO4.

[0098] In the B@TiO2@Mo@PP material obtained in this embodiment, the PP content is 16.7 wt%. The deposition cycle number of TiO2 is 10 cycles, and the deposition cycle number of Mo is 5 cycles.

[0099] Comparative Example 1: This comparative example provides a method for preparing B@TiO2, wherein the number of TiO2 deposition cycles is 10 cycles. The preparation steps in this comparative example are exactly the same as steps 1.1 to 1.4 in Example 2.

[0100] Comparative Example 2: This comparative example provides a method for preparing B@HTPB, wherein the content of HTPB is 16.7 wt%. The preparation steps of this comparative example are similar to those of Example 1, except that AP in Example 1 is replaced with HTPB and water is replaced with ethyl acetate; all other steps are identical to those of Example 1. In this comparative example, the number average molecular weight of hydroxyl-terminated polybutadiene (HTPB) is 2800.

[0101] Comparative Example 3: This comparative example presents a method for preparing a B / AP (ball milling) composite fuel to compare the effect of highly uniform nanoscale composite of B and energetic oxidant on the energy release performance of the composite energetic material. The AP content is 16.7 wt%. The preparation steps of this comparative example are as follows: weigh AP and boron powder according to the specified ratio, stir and mix AP and boron powder, and then composite them using a ball mill to obtain the B / AP (ball milling) composite fuel.

[0102] Comparative Example 4: This comparative example presents a method for preparing B / AP (impregnation method) composite fuel to compare the effect of spheroidization process on the energy release performance of composite energetic materials, wherein the AP content is 16.7 wt%. The preparation steps of this comparative example are as follows: weigh AP and boron powder according to the ratio, dissolve AP in water and add boron powder, stir with a magnetic stirrer for 15 min, stir evenly and impregnate for 1 h, then evaporate the solvent in an oven to dry the material, and mechanically crush the resulting block to obtain B / AP composite fuel.

[0103] Performance testing: First, DSC testing of boron-based energetic materials.

[0104] Weigh the boron-based energetic material into an alumina crucible and place it in a DSC testing device. Set the instrument's heating rate to 10℃ / min, the test temperature range to room temperature - 900℃, and the atmosphere to air. This will give you the DSC curve of the boron-based metastable composite energetic material.

[0105] Figure 5 DSC data plots for B, B@AP, B@TiO2@AP, B@TiO2@Mo@AP, and B@TiO2. (Example) Figure 5As shown in Table 1, the oxidation peak temperature of boron raw material is 677℃, and the oxidation peak temperature of B@AP is 668℃. AP (NH4ClO4) alone can slightly reduce the oxidation reaction temperature of boron, but the effect is relatively limited. The oxidation peak temperature of B@TiO2@AP is 570℃, indicating that the introduction of the ALDTiO2 modified layer can significantly advance the oxidation temperature of B. The oxidation peak temperature of B@TiO2 is 570℃, indicating that the TiO2 modified layer has a good effect on reducing the oxidation temperature of boron in the absence of AP, but it is not as effective as B@TiO2@AP. This is because AP can decompose at a lower temperature under the action of TiO2 to generate intermediate products with stronger oxidizing activity, such as HClO4 and ClO2, providing a more active reaction environment and more sufficient gas-phase energetic oxidant for the early oxidation of boron, thereby significantly reducing the exothermic oxidation temperature of boron powder. This also shows that AP and TiO2 modified layer have a very obvious synergistic effect in reducing the oxidation temperature of boron powder. The oxidation peak temperature of B@TiO2@Mo@AP was 524℃, indicating that the composite modification layer and AP had the most significant effect on reducing the oxidation temperature of boron. This is because the composite modification layer, through the combined mechanism of oxygen vacancies and catalytic reaction, synergistically promoted the oxidation process of boron with the gas-phase oxidation effect of AP decomposition, which greatly reduced the oxidation reaction temperature of boron and improved ignition and combustion performance.

[0106] Table 1. DSC peak temperatures of boron-based energetic materials

[0107] Second, the laser ignition delay time test of boron-based energetic materials.

[0108] Weigh a certain amount of boron-based energetic material into an alumina crucible, place the crucible in the sample slot of a laser ignition instrument, and set the instrument parameters as follows: frequency Hz: 1000; duty cycle (1-40%): 3; number of pulses: 300; pulse train output.

[0109] Figure 6 The image shows the laser ignition delay time data for B, B@AP, B@TiO2@AP, B@TiO2@Mo@AP, and B@TiO2. From... Figure 6 As shown in Table 2, the ignition delay time of B is 63.8 ms, and that of B@AP is 54.4 ms, which is about 15% lower than that of the raw boron powder. The ignition delay time of B@TiO2@AP is 38.4 ms, which is about 40% lower than that of the raw boron powder, demonstrating a very significant reduction in ignition delay. The lowest ignition delay time is found in B@TiO2@Mo@AP at 34.4 ms, which is 46% lower than that of the boron powder. This indicates that the synergistic effect of the composite modification layer and AP can significantly shorten the ignition delay time of the boron powder and improve its ignition and combustion performance during use.

[0110] The ignition delay time of B@TiO2 in the comparative example was 47.68 ms, which was lower than that of the raw boron powder, but the effect was not as significant as that of B@TiO2@AP. This indicates that AP and the modified layer can synergistically optimize the ignition performance of boron powder. In addition, the ignition delay time of B@HTPB in the comparative example was 66.16 ms, which did not optimize the performance of the raw boron powder; instead, it prolonged the ignition delay time and reduced the reactivity of the boron powder. The ignition delay times of B / AP (impregnation method) and B / AP (ball milling method) were 58.08 ms and 59.04 ms, respectively, which were lower than those of the raw material, but the effect was not as good as that of B@AP in this invention. This indicates that the nanoscale uniform composite of AP and boron powder and the spherical morphology are beneficial to shortening the ignition delay time of boron powder and improving its reactivity.

[0111] The three metastable composite energetic materials B@AP, B@TiO2@AP, and B@TiO2@Mo@AP prepared by this invention have a short ignition delay time. AP works synergistically with the unary modified layer and the composite modified layer to significantly reduce the ignition delay time of boron and enhance the reactivity of boron.

[0112] The laser ignition delay time of samples after replacing AP with AN and PP was also tested, and the results are shown in Table 2. The laser ignition delay time of B@AN and B@PP samples is not significantly different from that of B@AP. The laser ignition delay time of B@TiO2@AN and B@TiO2@PP samples is not significantly different from that of B@TiO2@AP. The laser ignition delay time of B@TiO2@Mo@AN and B@TiO2@Mo@PP samples is similar to that of B@TiO2@Mo@AP. This indicates that the type of energetic oxidant has little effect on the laser ignition delay time of the samples.

[0113] Table 2 Ignition Delay Time of Boron-Based Energetic Materials

[0114] Third, the calorific value test of boron-based energetic materials.

[0115] The additive (half a sheet of lens paper) and the test sample were weighed separately using an electronic balance. The weighed sample was then wrapped in the same lens paper and placed in a corundum crucible. An ignition wire and cotton thread were installed on the oxygen bomb holder. The cotton thread was pressed to the bottom of the lens paper wrapping the sample. 10 ml of deionized water was added to the oxygen bomb cartridge. The oxygen bomb holder was installed and the oxygen bomb cap was tightened. The oxygen bomb was then installed on the calorimeter. After inputting the mass of the test sample, the mass of the additive, and the calorific value of the additive into the computer control software, the test was started. The instrument displayed the calorific value test results after the test was completed.

[0116] Table 3 shows the calorific values ​​of these boron-based energetic materials. As can be seen from Table 3, the calorific value of raw material B is 22.4 kJ / g, that of B@AP is 24.1 kJ / g, that of B@AP@TiO2 is 25.8 kJ / g, and that of B@AP@TiO2@Mo is 32.6 kJ / g. The calorific value data shows that the calorific value of the nanocomposite energetic materials prepared in this invention is improved compared to the raw boron powder. The synergistic effect of AP and the modified layer significantly improves the calorific value of boron. Among them, the calorific value of the nanocomposite energetic materials containing the Mo modified layer is significantly improved. In addition, the calorific values ​​of samples after replacing AP with AN and PP were also tested, and the results are shown in Table 3. The calorific values ​​of B@AN and B@PP samples are not significantly different from those of B@AP. The calorific values ​​of B@TiO2@AN and B@TiO2@PP samples are not significantly different from those of B@TiO2@AP. The calorific values ​​of B@TiO2@Mo@AN and B@TiO2@Mo@PP samples are similar to those of B@TiO2@Mo@AP, indicating that the type of energetic oxidant has little effect on the calorific value of the samples.

[0117] The calorific value of B@TiO2 in the comparative example was 23.3 kJ / g, slightly higher than that of the raw boron powder, but the effect was not as significant as that of B@TiO2@AP. This indicates that AP and the modified layer can synergistically optimize the improvement of the calorific value of boron powder. In addition, the calorific value of B@HTPB in the comparative example was 19.6 kJ / g, which did not optimize the calorific value compared to the raw boron powder; instead, it reduced it. The ignition delay times of B / AP (impregnation method) and B / AP (ball milling method) were 23.1 kJ / g and 22.9 kJ / g, respectively, slightly higher than the raw material, but the effect was not as good as that of B@AP in this invention. This indicates that the nanoscale uniform composite of AP and boron powder and the spherical morphology are beneficial to shortening the ignition delay time of boron powder and improving the reactivity.

[0118] Table 3 Calorific value of boron-based energetic materials

[0119] In summary, energetic oxidants and modified layers (@TiO2 and @Mo) can synergistically optimize the improvement of the calorific value of boron powder. Among the modified layers, the Mo modified layer (@Mo) has a more significant effect on improving the calorific value of boron-based nanocomposite energetic materials.

Claims

1. A boron-based composite energetic material with high sphericity assembled with an oxidant, characterized in that, Includes a boron matrix on which energetic oxidants are assembled; The boron matrix is ​​boron powder, mono-modified boron powder, or binary modified boron powder; The mono-modified boron powder is prepared by depositing metal oxides on the surface of boron powder using atomic layer deposition; the binary modified boron powder is prepared by depositing metal oxides and molybdenum metal on the surface of boron powder using atomic layer deposition. The energetic oxidant is ammonium perchlorate, ammonium nitrate, or potassium perchlorate; The morphology of the boron-based composite energetic material is rough-surfaced spherical particles.

2. The high sphericity boron-based composite energetic material assembled with the oxidant as described in claim 1, characterized in that, The diameter of the spherical particles is 2 to 25 μm.

3. The high sphericity boron-based composite energetic material assembled with the oxidant as described in claim 1, characterized in that, The energetic oxidant accounts for 10 wt% to 20 wt% of the mass percentage in the high sphericity boron-based composite energetic material assembled with the oxidant.

4. The high sphericity boron-based composite energetic material assembled with the oxidant as described in claim 3, characterized in that, The energetic oxidant accounts for 16.7 wt% of the mass of the high sphericity boron-based composite energetic material assembled with the oxidant.

5. The high sphericity boron-based composite energetic material assembled with the oxidant as described in claim 1, characterized in that, The metal oxide is TiO2.

6. The high sphericity boron-based composite energetic material assembled with the oxidant as described in claim 5, characterized in that, The boron matrix is ​​boron powder B, mono-modified boron powder B@TiO2, or binary modified boron powder B@TiO2@Mo.

7. A method for preparing a high-sphericity boron-based composite energetic material assembled with an oxidant as described in any one of claims 1 to 6, characterized in that, This method uses spray drying to prepare high-sphericity boron-based composite energetic materials assembled with oxidants.

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