An electric energy sensitive composite particle, a preparation method and application thereof

Abstract

The application discloses an electric energy sensitive composite particle, a preparation method and application, the composite particle is a double-layer structure, the outer layer is a conductive polymer or metal nanoparticles, and has a response decomposition to electric energy; the inner core is a slow-burning flame retardant material, and can quickly suppress combustion after power failure. The preparation method comprises the following steps of material solution preparation, electrostatic spraying and post-processing steps, and the composite particle with a particle size of 200-400 mu m is obtained through drying and screening. When the composite particle is applied to electrically controlled solid propellant, sodium nitrate, sodium nitrate and lithium perchlorate are used as oxidants, epoxy resin is used as a binder, and the composite particle is added, and the prepared propellant can be quickly ignited (response time < 500 ms) under power-on, and can be quickly extinguished (extinguishing time < 350 ms) under power-off, so that the problems of traditional propellant dependence on mechanical devices and response delay are solved. The application has the advantages of simple process, low raw material cost, stable particle performance, and good industrialization prospect.

Description

Technical Field

[0001] This invention belongs to the field of novel solid propellant research, specifically relating to an energy-sensitive composite particle, its preparation method, and its application. Background Technology

[0002] Traditional solid propellants suffer from the inherent drawback of "one-time ignition, uncontrollable thrust," making them unsuitable for scenarios requiring repeated start-stop cycles, controllable thrust, or precise attitude control. For example, satellite attitude and orbit control relies on complex mechanical valves, leading to response delays, and missile penetration maneuvers cannot dynamically adjust thrust curves. Therefore, there is an urgent need for novel electrically controlled solid propellants that can directly regulate combustion with electrical energy. In the aerospace field, microsatellites and CubeSats require lightweight and integrated propulsion systems. Electrically controlled solid propellants eliminate the need for complex valve mechanisms, significantly reducing weight and adapting to orbit maintenance and attitude adjustment. In the defense field, they can achieve millisecond-level thrust adjustment to enhance missile penetration capabilities and improve battlefield survivability. Meanwhile, the electrical response characteristics of oxidants such as ammonium nitrate and lithium perchlorate, as well as conductive polymers, have been proven. Electrostatic spraying and other preparation processes are mature, meeting the requirements of "conductive-flame-retardant" synergistic design. This solves the problems of long ignition delays and difficult extinguishing associated with traditional electrically controlled propellants. Furthermore, the raw materials used are low-cost, and the preparation processes are simple, possessing the potential for large-scale production, providing a feasible path for their engineering application.

[0003] Traditional methods for preparing electrically controlled solid propellants often rely on mechanical mixing. These methods struggle to address the issues of uniform dispersion and interfacial bonding of multi-component materials, and also negatively impact the dispersibility of electrical energy. In particles prepared by mechanical mixing, the conductive phase (e.g., polyaniline, metal nanoparticles) and the flame-retardant phase (e.g., aluminum hydroxide, magnesium hydroxide) are prone to agglomeration or segregation, resulting in poor synergy between conductivity and flame retardancy in the propellant. This manifests as a long combustion delay time (ignition time greater than several seconds) and low extinguishing efficiency after power failure (extinguishing time greater than several seconds). Hydroxylamine nitrate-based electrically controlled solid propellants suffer from complex processes (requiring concentration of the hydroxylamine nitrate solution) and long production cycles (requiring several days), making mass production difficult. Furthermore, they are prone to melting during combustion, further affecting the propellant's combustion stability. Most technical solutions have not optimized the quantitative relationship between the "conductivity-flame retardancy" dual characteristics, failing to meet the differentiated requirements for response speed and combustion intensity in various scenarios.

[0004] Therefore, developing an energy-sensitive composite particle that combines high response sensitivity, precise controllability, self-extinguishing upon power failure, and the potential for large-scale preparation has become a pressing technical problem to be solved in this field. Summary of the Invention

[0005] To address the shortcomings and deficiencies of existing solid propellant technologies, and to overcome the problems of sluggish electrical response and uncontrollability in existing electrically controlled solid propellants, this invention aims to provide an energy-sensitive composite particle, its preparation method, and its application. This composite particle is prepared using electrostatic spraying technology and achieves a synergistic effect of "conductivity and flame retardancy" through a core-shell structure design. This invention features a simple process, low raw material costs, and the resulting composite particle improves the controllability of electrically controlled propellants and increases the number of repeated ignition / quenching cycles. It can ignite the propellant at a DC voltage of 200V.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An energy-sensitive composite particle, wherein the composite particle has a double-layer structure, including an outer layer and a core; The outer layer is an energy-sensitive material layer, which is a conductive polymer or metal nanoparticles; The core is an insensitive flame-retardant material, which is a metal hydroxide.

[0008] Optionally, the conductive polymer is polyaniline or polypyrrole; The metal nanoparticles mentioned are silver nanoparticles or copper nanoparticles.

[0009] Optionally, the metal hydroxide is aluminum hydroxide or magnesium hydroxide.

[0010] Optionally, the mass ratio of the conductive polymer or metal nanoparticles in the outer layer to the metal hydroxide in the core is 1:1 to 2:1; the particle size of the composite particles is 200 to 400 μm.

[0011] The preparation method of any of the energy-sensitive composite particles of the present invention includes the following steps: Step 1, Preparation of material solution: Core solution: The core flame retardant material is ground to the micron level and dispersed in a mixed solvent of ethanol, acetone and water at a mass fraction of 10% to 30%. 0.5% to 2% polyvinylpyrrolidone is added as a dispersant, and the mixture is stirred and ultrasonically to form a uniform suspension. Outer layer solution: Dissolve the outer layer conductive polymer or metal nanoparticles in an organic solvent to prepare a homogeneous solution with a concentration of 0.5% to 2% by mass; Step 2, electrostatic spraying: A dual-fluid electrostatic spraying system is used, which delivers the core solution and the outer layer solution through a coaxial dual-channel nozzle. The flow rate of the core solution is controlled at 0.1-0.5 mL / min and the flow rate of the outer layer solution is controlled at 0.5-1 mL / min. Atomization deposition is carried out under a voltage of 5-20 kV and a nozzle-collector plate spacing of 10-30 cm. Step 3, post-processing: The deposited particles are vacuum dried at 40-60℃ for 12-24 hours, and particles with a diameter of 200-400μm are screened out.

[0012] Optionally, in step one, the organic solvent is N,N-dimethylformamide or tetrahydrofuran.

[0013] Optionally, in step one, the volume ratio of ethanol, acetone and water in the mixed solvent is 4:3:3.

[0014] The application of any of the energy-sensitive composite particles described in this invention in the preparation of electrically controlled solid propellants.

[0015] Optionally, the composition of the electrically controlled solid propellant, by mass percentage, includes: Ammonium nitrate: 20%–30%; Lithium perchlorate: 35%–45%; Epoxy resin: 25%–32%; Energy-sensitive composite particles: 2%–10%.

[0016] Optionally, the preparation process of the electrically controlled solid propellant includes the following steps: Step 1: Under room temperature conditions, epoxy resin, ammonium nitrate and lithium perchlorate are mixed sequentially, and then the energy-sensitive composite particles are added. Under vacuum stirring, a uniform and bubble-free slurry is obtained; the stirring rate is controlled within the range of 50 to 70 rpm; the stirring time is within the range of 25 to 35 minutes. Step 2: The slurry obtained in Step 1 is directly poured into a polytetrafluoroethylene mold at room temperature, and then left to stand for 4 hours at normal pressure and room temperature to obtain a solidified electrically controlled propellant.

[0017] Compared with the prior art, the present invention has the following advantages: (1) The energy-sensitive multilayer composite particles of the present invention adopt electrostatic spraying technology, which does not require a complex curing process, and can be mass-produced through post-processing such as screening by vibrating screen, and have strong process adaptability.

[0018] (2) The outer layer uses conductive polymers or metal nanoparticles and other energy-sensitive materials, which can quickly generate Joule heating response under the action of electric field, while the core flame-retardant material can quickly suppress the reaction after power is cut off, so as to achieve precise start and stop under power regulation.

[0019] (3) The raw material composition is clear during the preparation process. Only outer sensitive material, core flame retardant material, basic solvent, dispersant, etc. are needed. No additional curing agent, crosslinking agent, etc. are required. The method is simple, the raw material cost is low, and the controllability of the combustion process can be achieved through parameter adjustment.

[0020] (4) Experimental verification shows that the ignition and shutdown response of the electrically controlled solid propellant using polyaniline / aluminum hydroxide composite particles in Example 1 is sensitive and controllable.

[0021] (5) The solvents and post-treatment methods used in the preparation process are green and environmentally friendly, and the vacuum drying and other steps are highly safe. The particles can be mixed with different matrices and applied to electronically controlled solid propellants to improve the controllability of propellant ignition and shutdown. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1 This is an electron microscope image of the composite particles in Example 1, showing polyaniline coating aluminum hydroxide. Figure 2 Example 1: Electrically Controlled Solid Propellant Figure 3 Photograph of the propellant burning at 200V in Example 1. Detailed Implementation

[0023] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and accompanying drawings, further clarifies the invention. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0024] This invention utilizes the unique electrochemical properties of ammonium nitrate and lithium perchlorate as oxidants, along with energy-sensitive composite particles that cross-link with epoxy resin to form a solid propellant. The addition of these energy-sensitive composite particles increases the propellant's conductivity, enhancing its electrical energy absorption under energization. When the power is disconnected, the aluminum hydroxide core of the composite particles absorbs heat, causing the propellant to extinguish immediately. This quaternary composite electrically controlled solid propellant can achieve ignition and extinguishing in response to electrical energy.

[0025] This invention provides a quaternary composite electrically controlled solid propellant containing energy-sensitive composite particles. This composite solid propellant meets the requirements of electrically controlled solid propellants and can be cured at room temperature. By mass percentage, the solid propellant is composed of the following raw materials: ammonium nitrate: 20%–30%; lithium perchlorate: 35%–45%; epoxy resin: 25%–32%; energy-sensitive composite particles: 2%–10%; the total of the above components is 100%.

[0026] In the embodiments of this disclosure, the composite particles are a double-layer structure, and the composite particles account for 2% to 10% of the total amount of the electrically controlled solid propellant.

[0027] In the embodiments of this disclosure, the outer layer of the composite particles is an energy-sensitive material layer, composed of conductive polymers or metal nanoparticles; the core is an insensitive flame-retardant material, including metal hydroxides.

[0028] In the embodiments disclosed herein, the conductive polymer of the outer layer is polyaniline or polypyrrole; the metal nanoparticles are silver nanoparticles or copper nanoparticles. In embodiments of this disclosure, the metal hydroxide of the core is aluminum hydroxide or magnesium hydroxide.

[0029] In the embodiments of this disclosure, the mass ratio of conductive polymer or metal nanoparticles in the outer layer to metal hydroxide in the core is 1:1 to 2:1; the particle size of the composite particles is 200 to 400 μm.

[0030] The method for preparing the energy-sensitive composite particles of the present invention specifically includes: Step 1, Preparation of material solution: Core solution: Grind the core flame retardant material to the micron level (about 200μm), disperse it in a mixed solvent of ethanol, acetone and deionized water at a mass fraction of 10% to 30%, add 0.5% to 2% polyvinylpyrrolidone as a dispersant, and stir and sonicate to form a uniform suspension. Outer layer solution: Dissolve the outer layer conductive polymer or metal nanoparticles in an organic solvent to prepare a homogeneous solution with a concentration of 0.5% to 2% by mass; Step 2, electrostatic spraying: A dual-fluid electrostatic spraying system is used to deliver the core solution and the outer layer solution through a coaxial dual-channel nozzle. The flow rate of the core solution is controlled at 0.1-0.5 mL / min and the flow rate of the outer layer solution is controlled at 0.5-1 mL / min. Atomization deposition is carried out under a voltage of 5-20 kV and a nozzle-collector plate spacing of 10-30 cm. Step 3, post-processing: The deposited particles are vacuum dried at 40–60℃ for 12–24 h, and particles with a diameter of 200–400 μm are screened out. The organic solvent in step one is N,N-dimethylformamide or tetrahydrofuran; the volume ratio of ethanol, acetone and water in the mixed solvent is 4:3:3.

[0031] A method for preparing a quaternary composite electrically controlled solid propellant containing energy-sensitive composite particles, wherein the quaternary composite electrically controlled solid propellant is the quaternary composite electrically controlled solid propellant containing energy-sensitive composite particles of the present invention; The preparation method of this propellant includes: dispersing ammonium nitrate and lithium perchlorate in epoxy resin, adding a small amount of energy-sensitive composite particles, vacuum stirring at room temperature for 25 to 35 minutes, and curing at room temperature under normal pressure for more than 4 hours to obtain an ammonium nitrate-lithium perchlorate-epoxy resin-composite particle quaternary composite electrically controlled solid propellant.

[0032] Step 1: Under room temperature conditions, epoxy resin, ammonium nitrate and lithium perchlorate are mixed sequentially, and then the energy-sensitive composite particles are added. Under vacuum stirring, a uniform and bubble-free slurry is obtained; the stirring rate is controlled within the range of 50 to 70 rpm; the stirring time is within the range of 25 to 35 minutes. Step 2: The well-stirred slurry obtained in Step 1 is directly poured into a polytetrafluoroethylene mold at room temperature. After standing for 4 hours at room temperature and normal pressure, the solidified electronically controlled propellant is obtained.

[0033] All raw materials used in the examples of this invention are commercially available products.

[0034] Following the above technical solutions, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0035] Example 1: Weigh the raw materials according to the formula in Table 1; This example provides a method for preparing energy-sensitive composite particles, including the following steps: Step 1, Preparation of material solution: Core solution: The core flame retardant material (aluminum hydroxide) is ground to the micron level (about 200μm) and dispersed at 10% by mass in a mixed solvent of ethanol, acetone and deionized water. 0.5% by mass of polyvinylpyrrolidone is added as a dispersant, and the mixture is stirred and sonicated to form a uniform suspension. The volume ratio of ethanol, acetone and deionized water is 4:3:3.

[0036] Outer layer solution: The outer conductive polymer (polyaniline) is dissolved in N,N-dimethylformamide to prepare a homogeneous solution with a concentration of 0.5% by mass.

[0037] Step 2, electrostatic spraying: A dual-fluid electrostatic spraying system is used, which delivers the core solution and the outer layer solution through a coaxial dual-channel nozzle. The flow rate of the core solution is controlled at 0.2 mL / min and the flow rate of the outer layer solution is controlled at 0.5 mL / min. Atomization deposition is carried out under a voltage of 10 kV and a nozzle-collector plate distance of 15 cm. Step 3, Post-processing: The deposited particles were vacuum dried at 50℃ for 12 hours, and particles with a diameter of 200-400 μm were screened out. This embodiment provides a method for preparing a quaternary composite electrically controlled solid propellant consisting of ammonium nitrate, lithium perchlorate, epoxy resin, and composite particles, including the following steps: Step 1: Under room temperature conditions, epoxy resin, ammonium nitrate and lithium perchlorate are mixed sequentially, and then electrical energy-sensitive composite particles are added. Under vacuum stirring, a uniform and bubble-free slurry is obtained.

[0038] Step 2: The well-stirred slurry obtained in Step 1 is directly poured into a polytetrafluoroethylene mold at room temperature. After standing for 4 hours at room temperature and normal pressure, the solidified electronically controlled propellant is obtained.

[0039] The stirring speed is controlled within a range of 45 rpm; the stirring time is controlled within a range of 35 minutes.

[0040] Table 1 Raw material formula table for Example 1

[0041] The measured ignition voltage of the propellant was 200V, and the propellant density was 1.54g / cm³. 3 The ignition is repeated 3 times, with a delay time of 300~500ms for each ignition and a shutdown delay time of 200~350ms.

[0042] Figure 1 This is an electron micrograph of the composite particles from Example 1, showing polyaniline-coated aluminum hydroxide; [The image is missing from the original text.] Figure 1 The results show that the surface of aluminum hydroxide particles changed from smooth to rough, exhibiting obvious coating characteristics, indicating that polyaniline has been successfully grown in situ or attached to the surface of the aluminum hydroxide matrix, forming a core-shell structured composite material with clear particle texture.

[0043] Figure 2 The electrically controlled solid propellant used in Example 1; Figure 2 The results show that the prepared propellant electron microscopy results show that each component is well encapsulated by epoxy resin, with only a small number of pores, which avoids uneven combustion.

[0044] Figure 3 These are photographs of the propellant burning at 200V in Example 1. (a) The propellant begins to smoke and produce sparks immediately after being energized; (b) It begins to burn; (c) It extinguishes after the power is turned off; (d) It ignites and produces sparks again after being energized again; (e) It then burns; (f) It extinguishes after the power is turned off. Figure 3 The results show that the combustion process demonstrates that the propellant has good electronic control characteristics, and can be started and stopped by switching the power on and off.

[0045] As can be seen from the results of the above embodiments, the electrically controlled solid propellant containing energy-sensitive composite particles prepared by the present invention can be prepared at room temperature. It can undergo ignition and combustion reaction under an applied voltage of 200V. After the power is cut off, the propellant stops burning, which improves the sensitivity to electrical response and reduces the ignition and extinguishing delay time of the propellant.

[0046] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0047] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0048] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. An energy-sensitive composite particle, characterized in that, The composite particles have a two-layer structure, consisting of an outer layer and a core. The outer layer is an energy-sensitive material layer, which is a conductive polymer or metal nanoparticles; The core is an insensitive flame-retardant material, which is a metal hydroxide.

2. The energy-sensitive composite particle according to claim 1, characterized in that, The conductive polymer is polyaniline or polypyrrole; The metal nanoparticles mentioned are silver nanoparticles or copper nanoparticles.

3. The energy-sensitive composite particle according to claim 1 or 2, characterized in that, The metal hydroxide is aluminum hydroxide or magnesium hydroxide.

4. The energy-sensitive composite particle according to claim 1 or 2, characterized in that, The mass ratio of the conductive polymer or metal nanoparticles in the outer layer to the metal hydroxide in the core is 1:1 to 2:

1. The particle size of the composite particles is 200–400 μm.

5. The method for preparing the energy-sensitive composite particles according to any one of claims 1-4, characterized in that, Includes the following steps: Step 1, Preparation of material solution: Core solution: The core flame retardant material is ground to the micron level and dispersed in a mixed solvent of ethanol, acetone and water at a mass fraction of 10% to 30%. 0.5% to 2% polyvinylpyrrolidone is added as a dispersant, and the mixture is stirred and ultrasonically to form a uniform suspension. Outer layer solution: Dissolve the outer layer conductive polymer or metal nanoparticles in an organic solvent to prepare a homogeneous solution with a concentration of 0.5% to 2% by mass; Step 2, electrostatic spraying: A dual-fluid electrostatic spraying system is used, which delivers the core solution and the outer layer solution through a coaxial dual-channel nozzle. The flow rate of the core solution is controlled at 0.1-0.5 mL / min and the flow rate of the outer layer solution is controlled at 0.5-1 mL / min. Atomization deposition is carried out under a voltage of 5-20 kV and a nozzle-collector plate spacing of 10-30 cm. Step 3, post-processing: The deposited particles are vacuum dried at 40-60℃ for 12-24 hours, and particles with a diameter of 200-400μm are screened out.

6. The method for preparing the energy-sensitive composite particles according to claim 5, characterized in that, In step one, the organic solvent is N,N-dimethylformamide or tetrahydrofuran.

7. The method for preparing the energy-sensitive composite particles according to claim 5, characterized in that, In step one, the volume ratio of ethanol, acetone and water in the mixed solvent is 4:3:

3.

8. The application of the energy-sensitive composite particles according to any one of claims 1-4 in the preparation of electrically controlled solid propellants.

9. The application according to claim 8, characterized in that, The electrically controlled solid propellant comprises, by weight percentage: Ammonium nitrate: 20%–30%; Lithium perchlorate: 35%–45%; Epoxy resin: 25%–32%; Energy-sensitive composite particles: 2%–10%.

10. The application according to claim 8 or 9, characterized in that, The preparation process of the electronically controlled solid propellant includes the following steps: Step 1: Under room temperature conditions, epoxy resin, ammonium nitrate and lithium perchlorate are mixed sequentially, and then the energy-sensitive composite particles are added. Under vacuum stirring, a uniform and bubble-free slurry is obtained; the stirring rate is controlled within the range of 50 to 70 rpm; the stirring time is within the range of 25 to 35 minutes. Step 2: The slurry obtained in Step 1 is directly poured into a polytetrafluoroethylene mold at room temperature, and then left to stand for 4 hours at normal pressure and room temperature to obtain a solidified electrically controlled propellant.

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