Inorganic multi-metal hydroxide@organic material core-shell structure explosion suppression material

Abstract

This invention discloses an inorganic multimetallic hydroxide@organic material core-shell structure explosion suppression material, belonging to the field of explosive safety protection technology. The explosion suppression material comprises a core layer and an outer shell layer; the core layer is an inorganic suppression phase with a multimetallic hydroxide framework and variable-valence metal centers, while the outer shell layer is an organic material shell layer with controllable softening temperature and thermal buffering capacity. The preparation method involves preparing multimetallic inorganic core layer powder using a co-precipitation method, and then coating the organic material onto the surface of the core particles using a melt-coating method. When applied to suppressing combustion and explosion accidents of solid propellants, the outer shell layer protects the particles from completely penetrating the flame layer and entering the combustion and explosion center region. Subsequently, it rapidly softens or destabilizes at high temperatures, releasing the core. Through multiple mechanisms such as heat absorption, capture of combustion free radicals, and formation of inert residue, it achieves rapid cooling and chemical suppression, effectively hindering combustion propagation and the transition from deflagration to detonation. Compared with existing explosion suppressants, this invention has a significant spatiotemporal synergistic explosion suppression effect and is suitable for the safety protection of high-energy solid propellants.

Description

Technical Field

[0001] This invention belongs to the field of explosives safety protection technology, and particularly relates to an inorganic polymetallic hydroxide@organic material core-shell structure explosion suppression material. Background Technology

[0002] During production, loading, inspection, storage, and transportation, explosives are highly susceptible to damage from mechanical impacts, friction, electrical sparks, localized overheating, or external ignition sources, which can induce localized combustion, deflagration, or even detonation. Once such accidents occur, the reaction and development are extremely rapid, and traditional passive protection methods are insufficient for timely intervention, often resulting in severe casualties and property damage.

[0003] Traditional safety protection measures mainly include: structural protection (such as explosion-proof walls, protective dikes, and isolation chambers), process protection (such as cooling, inert gas atmospheres, and remote operation), and passive protection (such as refractory and heat-insulating material coverings, partitions, and buffer pads). However, these measures mostly focus on mitigating the consequences of accidents or reducing the probability of accidents. In the process of an accident that has already occurred and continues to develop, there is a lack of "active explosion suppression materials" that can directly act on the surface of explosives and achieve rapid intervention.

[0004] Currently used powder extinguishing / explosion suppressants include sodium bicarbonate, sodium carbonate, ammonium phosphate, and some silicate powders. Their main mechanisms of action are endothermic thermal decomposition, release of non-combustible gases to dilute combustibles / oxygen, and formation of a protective layer. However, for solid high-energy materials such as explosives, the thermal decomposition process involves complex solid-phase reactions and gas-phase free radical chain reactions, resulting in extremely rapid local temperature rise. Inert powders typically only provide physical cooling and dilution, lacking effective chemical inhibition against the free radical chains of explosive decomposition. Furthermore, under extremely high heating and pressure rates, relying solely on inert powders makes it difficult to form a continuous and effective protective layer in a very short time.

[0005] While water spray and foam systems offer significant cooling, suffocation, and isolation effects in conventional fires, they have considerable limitations in fire and explosive accident scenarios. Firstly, water can cause severe thermal shock to the surface of high-temperature explosives, inducing crystal fragmentation, mechanical stress concentration, and even the formation of new "hot spots." Secondly, liquids struggle to penetrate the interior of solids already in a high-temperature decomposition state, limiting their ability to inhibit deeper reactions. Although fluorinated extinguishing agents possess some gas-phase suppression effects, they pose environmental and toxicity issues, and their suppression efficiency is not ideal for fire and explosive systems primarily characterized by solid-phase decomposition.

[0006] In summary, existing suppression materials are mainly designed for conventional fire and gas explosion scenarios. When dealing with high-energy explosive accidents, they have the following prominent problems: they lack effective chemical inhibition against solid-phase decomposition and free radical chain reactions; they are difficult to achieve the synergistic effect of "rapid cooling + free radical inhibition + gas dilution + formation of heat insulation and flame retardant layer" in a very short time; and some materials also have drawbacks such as environmental pollution, corrosiveness, or being unfriendly to equipment and personnel.

[0007] Composite solid propellants, as a typical representative of explosives, are widely used in rocket engines, missiles, and other fields. They are typically composed of oxidizers, organic binders, metallic fuels, and small amounts of functional additives, and are characterized by high energy density, high heat release rate, and the generation of large amounts of high-temperature gases and active free radicals during decomposition and combustion. Under conditions such as localized thermal runaway, accidental ignition, or damage to the engine casing, they can easily develop from initial combustion into rapid deflagration or even detonation. In such accidents, a high-temperature, high-pressure, and high-free-radical-concentration combustion-explosion center region rapidly forms inside and near the surface of the solid propellant grain. This region has a limited volume, extremely high temperature, and an extremely high rate of pressure rise, placing extremely high demands on traditional fire extinguishing and explosion suppression methods.

[0008] Therefore, there is still a lack of systematic solutions to the two major technical challenges in solid propellant accidents: how to ensure that the explosion suppression material maintains its particle structure integrity when entering the high-temperature and high-pressure combustion and explosion center region, and how to release it quickly and effectively act on the typical propellant combustion / deflagration free radical system after entering the region. Summary of the Invention

[0009] To address the limitations of existing anti-detonation powders in effectively penetrating the combustion-detonation core region and suppressing the deflagration-detonation transition in solid propellant combustion accidents, this invention proposes an inorganic multi-metal hydroxide@organic material core-shell structure anti-detonation material. This invention utilizes the mechanical integrity of the core-shell structured particles during operation to achieve directional penetration and transport of the anti-detonation material into the core region of the solid propellant combustion. Through the multi-metal hydroxide framework and variable-valence metal centers in the core layer, endothermic reactions, free radical capture, and inert residue formation are achieved at the characteristic temperature of the propellant flame, comprehensively reducing the combustion rate, flame temperature, and pressure rise rate, thus suppressing the development of deflagration into detonation.

[0010] To achieve the above objectives, the present invention provides the following technical solution: Technical Objective 1: An inorganic multimetallic hydroxide@organic material core-shell structured explosion suppression material, comprising: Kernel layer and outer shell layer; The core layer is an inorganic suppression phase with a multimetal hydroxide framework and variable valence metal centers; The outer shell is an organic shell with a controllable softening temperature and thermal buffering capacity. The thermal buffering capacity is manifested in the occurrence of endothermic phase transition and / or endothermic decomposition in the target temperature range, thereby reducing the local temperature rise rate and working in conjunction with the core suppression phase.

[0011] The core-shell explosion suppression material provided by this invention consists of an inorganic core layer and an organic shell layer. The inorganic core layer has a multi-metal hydroxide framework and variable-valence metal centers, enabling it to absorb heat at high temperatures, capture combustion free radicals, and generate inert residue. The organic shell layer has a controllable softening temperature, providing sufficient mechanical strength and flight stability to particles during explosion dispersion. Furthermore, it undergoes an endothermic phase transition and / or endothermic decomposition after reaching the characteristic temperature of the solid propellant flame, reducing the local temperature rise rate and rapidly destabilizing to release the core layer. This material significantly improves the effective concentration and efficiency of explosion suppression materials in the core region of solid propellant combustion, greatly enhancing the system's resistance to deflagration instability and detonation.

[0012] Its application principle is as follows: When a solid propellant grain or an engine containing solid propellant experiences combustion, deflagration, or thermal runaway, the deflagration suppression device rapidly disperses the core-shell deflagration material at a predetermined detonation pressure and location, allowing the particles to penetrate the initial flame layer in a largely intact form and enter the central region of combustion and detonation. Subsequently, within the target temperature range, the shell layer softens or becomes unstable, resulting in an endothermic phase transition or decomposition, reducing the local temperature rise rate, and simultaneously releasing the inorganic core phase with deflagration function. Thus, within the critical spatiotemporal window, a concentrated release of high-concentration suppressing components is achieved, effectively hindering combustion propagation and suppressing the transition from deflagration to detonation.

[0013] Furthermore, the multimetallic hydroxide of the core layer is composed of two or more metal elements, wherein the metal elements are selected from one or more of alkaline earth metals, aluminum-based metals, and transition metals; The variable-valence metal element is selected from one or more rare earth metals and variable-valence transition metals.

[0014] Furthermore, the alkaline earth metal is selected from one or more of Mg, Ca, Sr and Ba; The aluminum-based metal is Al; The transition metal is selected from one or more of Fe, Ni, Co, Zn and Mn; The rare earth metal is selected from one or more of Ce, La, Pr and Nd; The variable valence transition metal is selected from one or more of Fe, Mn, Cu, and Co.

[0015] Furthermore, the amount of the variable-valence metal is 5 to 30% of the sum of the amounts of the core layer metal cations.

[0016] Furthermore, the organic material of the outer shell layer is selected from thermoplastic resins or thermoplastic elastomers; The thermoplastic resin includes polyethylene, polypropylene, polyamide, or polyoxymethylene; (possessing the ability to absorb heat during melt phase change). The thermoplastic elastomer includes thermoplastic polyurethane or styrene block copolymer elastomers; (possessing thermal transition and melting / softening processes related to soft / hard segments, which can contribute a certain amount of heat capacity and phase change / softening endothermic heat) Furthermore, the inorganic polymetallic hydroxide@organic material core-shell structure explosion suppression material also includes additives, which are selected from one or more of inorganic / organic anti-caking agents, flow modifiers, surface treatment agents or wetting agents, and the total mass of the additives does not exceed 10% of the total mass of the inorganic polymetallic hydroxide@organic material core-shell structure explosion suppression material.

[0017] Furthermore, the mass ratio of the core layer to the outer shell layer is (60~80):(20~40).

[0018] Technical Objective 2: A method for preparing the inorganic multimetal hydroxide@organic material core-shell structure explosion suppression material, comprising the following steps: preparing multimetal inorganic core layer powder by co-precipitation method, mixing the core layer powder with the outer shell organic material, and coating the core particles with organic material by melt coating method to form inorganic multimetal hydroxide@organic material core-shell structure explosion suppression material.

[0019] Furthermore, the specific operation steps of the co-precipitation method include: preparing a mixed metal salt solution and a mixed alkali solution, adding the metal salt solution dropwise to the alkali solution under stirring to control the pH, and obtaining a multi-metal hydroxide powder after aging, washing, and drying; The specific steps of the melt coating method include: premixing the core powder with the outer shell organic material, then melting and mixing them at a shell phase softening or melting temperature, and then extruding and cooling.

[0020] Technical Objective 3: The application of the above-mentioned inorganic polymetallic hydroxide@organic material core-shell structure explosion suppression material in the suppression of solid propellant combustion and explosion accidents. The specific application method is as follows: the inorganic polymetallic hydroxide@organic material core-shell structure explosion suppression material is filled into an explosion suppression device. The device then disperses the material at high speed under a predetermined explosion pressure and location, allowing the particles to penetrate the initial flame layer in a basically intact form and enter the combustion and explosion center region. Subsequently, within the target temperature range, the shell layer softens or becomes unstable, releasing the inorganic core phase with explosion suppression function.

[0021] Compared with the prior art, the present invention has the following advantages and technical effects: 1. Significant Spatiotemporal Synergistic Detonation Suppression Effect: This invention utilizes a core-shell structure design. The organic outer shell provides mechanical strength and flight stability to the core during room temperature and injection, enabling particles to penetrate the initial flame layer with a relatively intact morphology and precisely enter the combustion center region of the solid propellant (spatial orientation). Upon entering the high-temperature region, the shell rapidly softens, melts, or pyrolyzes, releasing a high concentration of inorganic suppression core within a critical time window (time control), achieving spatiotemporal coupling of the inhibitor from "transport" to "release." Experimental results show that, compared to traditional ammonium dihydrogen phosphate powder, the material of this invention causes a "steep and rapid drop" in propellant flame temperature upon triggering, almost instantaneously falling from a high level above 1200°C to a low-temperature region, directly terminating combustion, while traditional materials only cause a slow and limited temperature decrease.

[0022] 2. Overcomes the application defects of traditional explosion suppression materials: Compared with traditional inert powders such as sodium bicarbonate and ammonium phosphate that only provide physical cooling / dilution, this invention provides active chemical inhibition of solid phase decomposition and free radical chain reaction of solid propellants; compared with water spray systems that pose a risk of thermal shock, this invention is a dry powder that will not cause severe thermal shock to the surface of high-temperature propellants or induce new "hot spots"; compared with fluorinated fire extinguishing agents, this invention does not involve persistent organic pollutants or toxicity issues, making it more environmentally friendly and safer.

[0023] 3. Widely applicable to high-energy solid propellant combustion and explosion scenarios: This invention is specifically designed for the high energy density, high heat release rate, and large-scale generation of active free radicals characteristic of composite solid propellants (such as hydroxyl-butyl propellants). It can rapidly respond and directly act on the core combustion and explosion region under extreme conditions such as thermal runaway, accidental ignition, or engine casing damage. The excellent suppression effect is verified using a typical hydroxyl-butyl composite solid propellant in the embodiments, demonstrating the important safety protection application value of this invention in military and aerospace fields such as rocket engines and missiles.

[0024] 4. High structural design flexibility and simple preparation process: By adjusting the type of organic material in the outer shell (such as thermoplastic polyurethane, polyethylene, polypropylene, etc.) and the molar fraction of variable-valence metal in the core layer (5~30%), the softening / instability temperature of the shell layer and the release timing of the core layer can be flexibly controlled according to the combustion characteristic temperature window of different propellants. At the same time, the process route of preparing core powder by co-precipitation combined with melt coating is mature, easy to scale up for production, and conducive to industrial promotion. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1Curves showing the temperature variation of solid propellant combustion for different suppression materials. Detailed Implementation

[0026] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0027] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0028] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0029] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0030] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0031] This invention provides an inorganic multimetal hydroxide@organic material core-shell structure explosion suppression material, comprising: an inner core layer, an outer shell layer, and selectively added additives; The core layer is an inorganic suppression phase with a multimetal hydroxide framework and variable valence metal centers, which is used to absorb heat, capture free radicals and form inert residues in high-temperature combustion and explosion environments. The outer shell is an organic material shell with a controllable softening temperature, which is used to provide the particles with the required mechanical strength and integrity during the explosion suppression process. At the same time, it undergoes endothermic phase change and / or endothermic decomposition to reduce the local temperature rise rate, and softens, melts or pyrolyzes within the characteristic temperature range of solid propellant combustion to release the internal inorganic suppression core, thereby achieving spatial orientation and temporal control of the inhibitor. Additives used to improve the flowability, anti-caking properties, and storage stability of core-shell particles.

[0032] In some optional embodiments of the present invention, the core layer may be formed at high temperature containing Ce. 3+ / Ce 4+ Fe 2+ / Fe 3+ Reversible redox centers can target NO produced by the combustion of solid propellants. x Free radicals such as ·OH and ·H undergo adsorption and valence state transformation, thereby interrupting or weakening the chain combustion reaction. The polymetallic hydroxide is composed of two or more metal elements, selected from one or more of alkaline earth metals (Mg, Ca, Sr, or Ba), aluminum group metals (Al), and transition metals (Fe, Ni, Co, Zn, or Mn); the variable valence metal element is selected from one or more of rare earth metals (Ce, La, Pr, or Nd) and variable valence transition metals (Fe, Mn, Cu, or Co). For example, if the variable valence metal element is selected from one or a combination of Ce, La, and Fe, its molar fraction in the total number of metal cations in the core layer is 5-30%. Exemplarily, in the following preferred embodiments of the present invention, the polymetallic hydroxide is selected from alkaline earth metals (Mg) and aluminum group metals (Al), and the variable valence metal element is selected from rare earth metals (La), that is, the core layer is selected from a combination of alkaline earth metals (Mg), aluminum group metals (Al), and rare earth metals (La).

[0033] In some optional embodiments of the present invention, the outer shell layer is made of organic material, which remains solid and possesses a certain mechanical strength under normal temperature and storage conditions, while also having thermal buffering capacity, enabling it to protect the core from premature breakage during typical detonation suppression processes. The softening temperature of this organic shell layer is controllable, and its thermal buffering capacity manifests as an endothermic phase transition or decomposition within the target temperature range, thereby reducing the local temperature rise rate and working synergistically with the core's suppressive phase. Furthermore, the outer shell layer can soften, melt, or pyrolyze within the characteristic temperature range of solid propellant combustion or deflagration, causing the shell layer to become unstable, crack, or shrink, thereby exposing and releasing the inorganic suppressive phase of the core; it exhibits good compatibility with the core, uniform coating, and can form a substantially continuous shell structure. The organic material of the outer shell layer is selected from one or more thermoplastic resins and thermoplastic elastomers; thermoplastic resins include polyolefin resins (polyethylene, polypropylene), polyamide (PA), and polyoxymethylene (POM); thermoplastic elastomers include thermoplastic polyurethane (TPU) and styrene block copolymer elastomers (SBS, SEBS). For example, in the following preferred embodiments of the present invention, the organic material of the outer shell layer is selected as thermoplastic polyurethane. This material is stable at room temperature and has good mechanical strength. It does not react adversely with the inorganic inhibitory phase of the core and the solid propellant. In the solid propellant flame environment, its softening, melting or thermal decomposition temperature is lower than the temperature of the local high temperature zone of the propellant flame. The thermal decomposition temperature is about 280°C, which can ensure that the particles respond quickly to the shell breaking after approaching or entering the combustion and explosion center area.

[0034] In some optional embodiments of the present invention, the additives are selected from one or more of inorganic / organic anti-caking agents (" / " means "or") (such as talc, silica, fatty acid salts, etc.), flow modifiers, surface treatment agents or wetting agents, and the total mass of the additives does not exceed 10% of the total mass of the inorganic polymetallic hydroxide@organic material core-shell structure explosion suppression material.

[0035] Adding appropriate amounts of additives can generally improve powder handling properties, enhance the uniformity of the core-shell structure, and improve mechanical stability. However, excessive addition may lead to changes in the shell ratio, interfacial interference, and other issues, thereby affecting the overall material properties. Therefore, the total amount added is usually limited to no more than 10% of the system mass.

[0036] Among them: anti-caking agents have good compatibility with inorganic core surfaces, do not change the core phase structure, and do not affect the rheological properties of the system; talc, silica, fatty acid salts, etc. can be selected. Surface treatment agents have polarity matching with organic shells and can improve interfacial bonding; stearates (such as calcium stearate, magnesium stearate, etc.) can be selected. Surface treatment agents or wetting agents can reduce the viscosity of molten polymers and improve wetting ability; polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA) flow aids, etc. can be selected.

[0037] In the preparation of inorganic multimetal hydroxide@organic material core-shell composite materials, a composite additive (composed of anti-caking components and surface treatment agents) with a mass fraction of 5% was added to improve the dispersibility of inorganic core particles and the uniformity of molten TPU coating. The resulting material exhibited better powder flowability and a more uniform shell film structure. Compared with the sample without the additive, the composite material showed improved particle dispersion uniformity, more continuous shell, and more stable interfacial bonding in morphological observation.

[0038] In some optional embodiments of the present invention, the mass ratio of the core layer to the outer shell layer is 70:30.

[0039] The mechanism of action of the inorganic multimetal hydroxide@organic material core-shell structure explosion suppression material provided by this invention includes: 1) Space-directed transport: Core-shell particles, protected by the outer shell, fly in the form of near-rigid particles during the explosion dispersion, penetrate the initial flame layer, and enter the solid propellant combustion center and its vicinity. 2) Release within a time window: After the particles enter the high-temperature region, the shell layer softens / decomposes rapidly, releasing the inorganic inhibitory phase in the core, causing the inhibitor to reach a relatively high concentration instantaneously in the propellant combustion center region; 3) Shell-core phase thermo-chemical multiple suppression: The outer shell layer possesses a triple function of mechanical strength, thermal buffering (endothermic / phase change / pyrolysis), and destabilization release core. At high temperatures, the inorganic core layer reduces local temperature, weakens the combustion chain reaction, and blocks heat conduction and gas transport through mechanisms such as endothermic absorption, free radical capture, and the formation of inert residues. The shell-core combination suppresses combustion rate, reduces flame temperature, and slows pressure rise, thus weakening the transition from deflagration to detonation. The preparation method of the above-mentioned inorganic multimetallic hydroxide@organic material core-shell structure explosion suppression material includes the following steps: (1) Prepare a mixed metal salt solution and a mixed alkali solution. Add the metal salt solution dropwise to the alkali solution while stirring to control the pH. After aging, washing and drying, obtain a multi-metal hydroxide powder. (2) After premixing the core powder (polymetallic hydroxide powder) with the outer shell organic material, the core powder (polymetallic hydroxide powder) is melt-mixed at the shell phase softening or melting temperature, and then extruded and cooled to form an inorganic polymetallic hydroxide@organic material core-shell structure explosion suppression material.

[0040] The aforementioned inorganic polymetallic hydroxide@organic material core-shell structure explosion suppression material can be applied to the suppression of solid propellant combustion and explosion accidents. The specific application method is as follows: the inorganic polymetallic hydroxide@organic material core-shell structure explosion suppression material is filled into an explosion suppression device. The device then disperses the material at high speed under a predetermined blast pressure and location, allowing the particles to penetrate the initial flame layer in a basically intact form and enter the combustion and explosion center region. Subsequently, within the target temperature range, the shell layer softens or becomes unstable, releasing the inorganic core phase with explosion suppression function.

[0041] Unless otherwise specified, "room temperature" in this invention refers to 25±2℃.

[0042] All raw materials used in this invention were purchased from the market.

[0043] The technical solution of the present invention will be further illustrated by the following embodiments.

[0044] Example 1 A method for preparing an inorganic multimetal hydroxide@organic material core-shell structured explosion suppression material, comprising the following steps: (1) Preparation of the core inorganic suppressor phase (Mg-Al-La polymetallic hydroxide) 1) Preparation of polymetallic salt solutions Weigh out 0.30 mol of magnesium nitrate hexahydrate (Mg(NO3)2·6H2O), 0.10 mol of aluminum nitrate nonahydrate (Al(NO3)3·9H2O), and 0.03 mol of lanthanum nitrate hexahydrate (La(NO3)3·6H2O) according to the molar ratio of metal elements Mg:Al:La = 3:1:0.3. Place the three nitrates in the same beaker, add an appropriate amount of deionized water, stir until completely dissolved, transfer the resulting solution to a 400 mL volumetric flask, dilute to the mark with deionized water, and shake well to obtain mixed metal salt solution A. The total concentration of metal ions in this solution is calculated to be 1.075 mol / L. 2) Coprecipitation reaction and crystallization Weigh 0.40 mol sodium hydroxide (NaOH, 16.0 g) and 0.20 mol sodium carbonate (Na2CO3, 21.2 g), place them in the same beaker, add an appropriate amount of deionized water and stir to dissolve. After complete dissolution, transfer the solution to an 800 mL volumetric flask, dilute to the mark with deionized water, and shake well to obtain mixed alkaline solution B. The mixed alkaline solution B was transferred to a 2L reactor, a mechanical stirrer was installed, and the stirring speed was set to 400 rpm. The reactor temperature was controlled at 60℃ using a water bath. Two constant flow pumps were used to simultaneously add the mixed metal salt solution A and deionized water to the mixed alkaline solution B in the reactor at a flow rate of 2.0 mL / min. The total addition time was approximately 200 min. During the addition, the pH value of the reaction system was continuously monitored, and the pH value was adjusted with 2 mol / L sodium hydroxide solution to maintain it within the range of 10.5 ± 0.1. After the addition was completed, the system was stirred and aged at 60℃ and 400 rpm for 8 h to promote the full formation and crystallization stability of the polymetallic hydroxide framework. 3) Separation, washing and drying After the reaction is complete, the resulting slurry is filtered or centrifuged to collect the solid product. The solid product is repeatedly washed with deionized water until the conductivity of the washing liquid drops to a low level to remove residual soluble salts and other ionic impurities. The washed solid product is then placed in an 80°C oven and dried for 8 hours to obtain multi-metal hydroxide powder. (2) Preparation of inorganic polymetallic hydroxide@organic material core-shell structure explosion suppression material Weigh 700g of the prepared inorganic core suppressor powder and 300g of thermoplastic polyurethane (TPU) particles. Premix the weighed inorganic core suppressor powder and TPU particles for 10 minutes, and then melt mix them at 110℃ (the softening / melting temperature of the shell phase) to fully wet and uniformly coat the surface of the inorganic core particles with molten TPU. Add the resulting mixture to a twin-screw extruder for extrusion. After cooling, the inorganic polymetallic hydroxide@organic material core-shell structure explosion suppressor material is obtained.

[0045] Application Example 1: Evaluation of the suppression effect of inorganic polymetallic hydroxide @ organic material core-shell structured explosion suppression material 1. Test subjects A typical hydroxyl-butadiene (HPP) composite solid propellant was selected as the representative explosive material. This propellant is an HPP (Al / AP / HTPB) solid propellant with a solid content of 85%, of which AP accounts for 70%, Al 15%, and other components 15%. It has dimensions of φ25mm × h30mm, a mass of 25g, and a burning rate of 25.5mm / s. Using this type of propellant as the test object, the spatiotemporal suppression effect of the nuclear-shell explosion suppression material in this embodiment under typical solid propellant conditions was evaluated.

[0046] 2. Comparison of materials and pretreatment Meanwhile, ammonium dihydrogen phosphate was selected as a control for the explosion suppressant. Before the experiment, the inorganic polymetallic hydroxide@organic material core-shell structure explosion suppressant material (hereinafter referred to as "core-shell structure explosion suppressant material" in the figure) prepared in Example 1 and ammonium dihydrogen phosphate were dried at 60°C for 3 hours and kept dry for later use.

[0047] 3. Explosion suppression device and its arrangement The dried material was loaded into a sealed container with a capacity of 4L for the explosion suppression device. The device, after pressurization, used a pressure injection structure to spray the explosion suppression material into the solid propellant combustion field. During the test, the explosion suppression device was pressurized to 1MPa and positioned above the solid propellant grain, at a distance of 0.50m from the propellant surface, with the injection outlet pointing towards the center of the propellant grain.

[0048] 4. Testing and recording equipment An infrared thermal imager was installed 1 meter away from the experimental setup to monitor the temperature of the propellant surface and the surrounding flame area, and to record the temperature changes over time throughout the process. Simultaneously, a high-speed camera was used to record images of the suppression process.

[0049] 5. Test Operation Procedure First, the solid propellant grain is ignited by an igniter. Once the solid propellant reaches a stable flame temperature (defined as 3 seconds in this invention), a deflagration device is triggered, causing the material to be ejected at high speed under a predetermined pressure and dispersed onto the surface of the solid propellant and the surrounding high-temperature gas area. An infrared thermal imager and a high-speed camera simultaneously record data during the deflagration process, and the results are as follows: Figure 1 As shown.

[0050] Depend on Figure 1 It can be seen that the three temperature rise curves in the initial stage of ignition have basically the same trend, all rising rapidly to the high temperature zone in a short period of time (within 2 seconds) and stabilizing in a temperature range of not less than 1200℃. Without the addition of inhibitory materials, the propellant combustion only slowly decreases after reaching the peak temperature and remains in the high temperature zone of about 1200℃ for a long time, indicating that the propellant combustion is intense and the high temperature lasts for a long time.

[0051] When the explosion suppression device filled with ammonium dihydrogen phosphate was triggered, the temperature dropped momentarily, but the rate of drop was slow, and the peak temperature reduction was limited. Subsequently, the temperature rose rapidly and remained at a high temperature for a long time. This indicates that although conventional powder explosion suppressants can exert a certain inhibitory effect through mechanisms such as endothermic decomposition, release of non-combustible gases, and surface coverage, their ability to rapidly cool the core area of ​​combustion and explosion is limited, making it difficult to significantly weaken the combustion intensity in a short period of time, resulting in insufficient suppression effect.

[0052] When the explosion suppression material of the core-shell structure is triggered by the explosion suppression device, the temperature drops sharply and almost instantly from a high level to a low temperature zone, directly terminating the combustion of the propellant.

[0053] Mechanism Analysis: Based on the core-shell structure design of this invention, the above differences can be attributed to the following mechanisms: On the one hand, under the protection of the organic outer shell, the core-shell particles penetrate the flame front with high momentum and enter the propellant combustion center region, achieving spatial directional transport of the explosion suppression material; on the other hand, after entering the high-temperature region, the shell layer rapidly softens or decomposes, releasing a multi-metallic inorganic core with variable-valence metal centers. This core achieves rapid cooling and chemical suppression of the combustion core region through multiple functions such as endothermic decomposition, free radical capture, and the formation of inert residue.

[0054] Conclusion: Compared with conventional ammonium dihydrogen phosphate powder, the core-shell explosion suppression material provided by this invention not only significantly reduces the peak temperature and duration of high-temperature combustion in solid propellants, but also exhibits superior performance in suppressing combustion resurgence and deflagration development. The above experimental results demonstrate that the core-shell structure explosion suppression material and its application method of this invention can achieve rapid and effective suppression of the core region of combustion and explosion in solid propellant combustion and explosion accidents, demonstrating significant technical advantages over traditional powder explosion suppression agents.

[0055] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An inorganic multimetallic hydroxide@organic material core-shell structured explosion suppression material, characterized in that, include: Kernel layer and outer shell layer; The core layer is an inorganic suppression phase with a multimetal hydroxide framework and variable valence metal centers; The outer shell is an organic material shell with controllable softening temperature and thermal buffering capacity.

2. The inorganic multimetal hydroxide@organic material core-shell structure explosion suppression material according to claim 1, characterized in that, The multimetallic hydroxide of the core layer is composed of two or more metallic elements, wherein the metallic elements are selected from one or more of alkaline earth metals, aluminum-based metals and transition metals. The variable-valence metal is selected from one or more rare earth metals and variable-valence transition metals.

3. The inorganic multimetal hydroxide@organic material core-shell structure explosion suppression material according to claim 2, characterized in that, The alkaline earth metal is selected from one or more of Mg, Ca, Sr and Ba; The aluminum-based metal is Al; The transition metal is selected from one or more of Fe, Ni, Co, Zn and Mn; The rare earth metal is selected from one or more of Ce, La, Pr and Nd; The variable valence transition metal is selected from one or more of Fe, Mn, Cu, and Co.

4. The inorganic multimetal hydroxide@organic material core-shell structure explosion suppression material according to claim 1, characterized in that, The amount of the variable-valence metal is 5 to 30% of the sum of the amounts of the core layer metal cations.

5. The inorganic multimetal hydroxide@organic material core-shell structure explosion suppression material according to claim 1, characterized in that, The organic material of the outer shell layer is selected from thermoplastic resins or thermoplastic elastomers; The thermoplastic resin includes polyethylene, polypropylene, polyamide, or polyoxymethylene; The thermoplastic elastomer includes thermoplastic polyurethane or styrene block copolymer elastomers.

6. The inorganic multimetal hydroxide@organic material core-shell structure explosion suppression material according to claim 1, characterized in that, It also includes additives, which are selected from one or more of inorganic / organic anti-caking agents, flow modifiers, surface treatment agents or wetting agents, and the total mass of the additives does not exceed 10% of the total mass of the inorganic polymetallic hydroxide@organic material core-shell structure explosion suppression material.

7. The inorganic multimetal hydroxide@organic material core-shell structure explosion suppression material according to claim 1, characterized in that, The mass ratio of the core layer to the outer shell layer is (60~80):(20~40).

8. A method for preparing an inorganic multimetal hydroxide@organic material core-shell structured explosion suppressant material as described in any one of claims 1 to 7, characterized in that, Includes the following steps: A multi-metal inorganic core layer powder was prepared by co-precipitation method. The core layer powder was then mixed with an outer shell organic material. The organic material was then coated onto the core particles by melt coating method to form an inorganic multi-metal hydroxide@organic material core-shell structure explosion suppression material.

9. The preparation method according to claim 8, characterized in that, The specific steps of the co-precipitation method include: preparing a mixed metal salt solution and a mixed alkali solution; adding the metal salt solution dropwise to the alkali solution under stirring to control the pH; and obtaining a multi-metal hydroxide powder after aging, washing, and drying. The specific steps of the melt coating method include: premixing the core powder with the outer shell organic material, then melting and mixing them at a shell phase softening or melting temperature, and then extruding and cooling.

10. The application of an inorganic multimetal hydroxide@organic material core-shell structure explosion suppressor as described in any one of claims 1 to 7 in the suppression of solid propellant combustion and explosion accidents.

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