A core-shell coated energetic composite material, a preparation method and application thereof

Abstract

The application provides a core-shell coated energetic composite material and a preparation method and application thereof. The preparation method comprises the following steps: (1) reacting a mixed solution containing AlH3, a fatty acid and a transition metal salt to form a fatty acid salt coating layer on the surface of the AlH3, and obtaining AlH3@MSA; and (2) performing spray drying on the mixture of the AlH3@MSA and a propellant and an oxidizing agent to obtain the core-shell coated energetic composite material. The core-shell coated energetic composite material prepared by the application has a controllable structure, excellent stability, complete combustion, and the preparation method is simple, low in cost and suitable for large-scale production.

Description

Technical Field

[0001] This invention specifically relates to a core-shell coated energetic composite material, its preparation method, and its application. Background Technology

[0002] Solid propellants are the energy and working fluid source for solid rocket engines, and their performance fundamentally determines the engine's energy characteristics. They are widely used in weaponry, missile systems, and satellite launches. Therefore, developing high-energy solid propellants is a key step in promoting the upgrading of aerospace propulsion systems. Among various solid propellant systems, composite solid propellants are widely used due to their advantages such as high energy density, good safety performance, and excellent mechanical properties. To further improve propellant energy levels, metallic fuels are often widely used in solid propellants, and the condensed particles produced by the combustion of metallic fuels can also alleviate the high-frequency unstable combustion phenomenon of engines to some extent. Among them, aluminum (Al) has advantages such as high density, high heat of combustion, low oxygen consumption, and high cost-effectiveness. Using it as a propellant component can not only improve the energy density of the propellant but also increase the specific impulse of the engine. However, the agglomeration phenomenon during the combustion of Al powder can lead to incomplete combustion, causing problems such as two-phase flow losses, residue accumulation, and nozzle erosion, and even affecting the normal operation of the engine.

[0003] Aluminum trihydride (AlH3) is considered an ideal candidate fuel to replace Al powder in the propellant field due to its high mass and volumetric hydrogen storage capacity. On the one hand, introducing AlH3 can significantly reduce the average molecular weight of the combustion gas by releasing hydrogen, thereby effectively improving the specific impulse of the propellant; on the other hand, its high reactivity helps to improve combustion efficiency. According to predictions from the U.S. Department of Defense, replacing Al powder with AlH3 can increase the specific impulse of solid propellants, solid-liquid propellants, and liquid propellants by 10 s, 32 s, and 27 s, respectively. Theoretical calculations show that replacing Al in HTPB / AP / Al propellants with AlH3 increases the theoretical specific impulse of the propellant from 305 s to 318 s, while simultaneously reducing the combustion temperature from 3579 K to 3021 K. These results demonstrate that replacing Al powder with AlH3 can significantly improve the energy performance of solid propellants, while also substantially reducing the combustion temperature and minimizing the erosion of engine nozzles by high-temperature combustion gases. AlH3 is considered an ideal fuel for the next generation of solid propellants and has promising application prospects.

[0004] However, AlH3 has poor chemical and thermal stability and is prone to slow decomposition during storage, which affects the safe storage and energy release of the propellant system and severely limits its widespread application in the field of propellants. Summary of the Invention

[0005] This invention aims to overcome the problems of poor stability, easy decomposition, and insufficient interfacial coupling between aluminum trihydride (AlH3) and oxidants in existing technologies, and provides a core-shell coated energetic composite material, its preparation method, and its applications. The core-shell coated energetic composite material prepared by this invention has a controllable structure, excellent stability, more complete combustion, and the preparation method is simple, low-cost, and suitable for large-scale production.

[0006] This invention utilizes a combination of in-situ synthesis and spray drying techniques. First, an AlH3@MSA coating layer is formed on the surface of AlH3 particles through an in-situ reaction, yielding an AlH3@MSA intermediate. This intermediate is then mixed with a propellant oxidant and spray-dried to prepare a core-shell coated energetic composite material. In this composite material, the inner AlH3 coating layer effectively isolates AlH3 from the external environment, improving its storage stability. The outer propellant oxidant layer acts as a high-energy oxidant, releasing oxygen during combustion to promote the complete oxidation of AlH3. Simultaneously, the transition metal ions in the AlH3 coating catalyze the thermal decomposition of the oxidant. The synergistic catalytic effect of the inner and outer coating layers enhances the heat of reaction, resulting in more complete combustion and further improving the energy release characteristics of the composite material. The preparation method of this invention achieves a dense and uniform coating of the AlH3 coating and oxidant, overcoming the problems of uneven coating and easy separation associated with physical mixing methods.

[0007] The present invention solves the above-mentioned technical problems through the following technical solutions:

[0008] This invention provides a method for preparing a core-shell coated energetic composite material, comprising the following steps:

[0009] (1) A mixture containing AlH3, fatty acids and transition metal salts is reacted to form a fatty acid coating layer on the surface of AlH3 to obtain AlH3@MSA;

[0010] (2) The mixture of AlH3@MSA and propellant with oxidant is spray-dried to obtain the core-shell coated energetic composite material.

[0011] In step (1), the fatty acid is preferably a long-chain fatty acid with more than 12 carbon atoms, and more preferably a long-chain fatty acid with 13-20 carbon atoms, such as stearic acid.

[0012] In step (1), the transition metal salt can be a conventional transition metal salt that can form an insoluble salt with fatty acids, preferably one or more of iron salt, cobalt salt and copper salt, and more preferably cobalt salt.

[0013] The iron salt may be one or more of ferrous sulfate, ferrous chloride, ferrous nitrate, ferric sulfate, ferric chloride, and ferric nitrate; the cobalt salt may be one or more of cobalt sulfate, cobalt chloride, and cobalt nitrate; and the copper salt may be one or more of copper sulfate, copper chloride, and copper nitrate.

[0014] In step (1), the solvent in the mixture can be a conventional solvent in the art that can promote the dissolution of fatty acids and the dispersion of AlH3, generally deionized water and / or ethanol.

[0015] When the solvent in the mixture is an ethanol-water mixture, the volume ratio of ethanol to water can be (0.5-3):1, for example, 1:1.

[0016] In step (1), the molar ratio of the fatty acid to the metal ion in the transition metal salt can generally be added according to the stoichiometric ratio. Usually, the amount of fatty acid can also be appropriately increased, preferably (1-5):1, more preferably (1.5-3.5):1, for example 2:1, 2.5:1 or 3:1.

[0017] In step (1), the mass ratio of the fatty acid salts generated in the reaction system to the AlH3 is preferably (1-20):100, more preferably (1-10):100, for example 2:100, 3:100, 5:100 or 8:100. The fatty acid salts generated in the reaction system are the theoretical fatty acid salts generated based on the added fatty acids and transition metal salts. The mass ratio affects the thickness and coating efficiency of the coating layer. Too much AlH3 may lead to incomplete coating, while too little may result in an overly thick coating layer, reducing the energy density.

[0018] In step (1), the molar concentration of the fatty acid in the mixture can be 0.5-10 mol / L, for example 1 mol / L, 1.5 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.5 mol / L, 3 mol / L or 5 mol / L.

[0019] In step (1), the reaction temperature can be 25-60℃, preferably 30-50℃, such as 30℃, 35℃, 40℃, 45℃, or 50℃; the reaction time can be 30-120 min, preferably 30-90 min, such as 45 min, 60 min, or 80 min. The reaction is generally carried out under normal pressure. If the reaction temperature is too low, the reaction rate will be slow and the coating layer will be uneven; if the temperature is too high, AlH3 may decompose.

[0020] In step (1), the reaction is generally carried out under mixed conditions, such as under stirring or ultrasonic conditions. The stirring speed can be 200-800 r / min, preferably 400-600 r / min, for example, 500 r / min. After the reaction is completed, solid-liquid separation, washing, and drying are generally required. The solid-liquid separation can be achieved by filtration or centrifugation; the washing can be done with deionized water and / or ethanol; the washing can be performed 3-5 times; the drying is generally carried out in a vacuum oven at a temperature of 40-60℃; the drying time can be 4-12 hours.

[0021] In step (1), the method for preparing the mixture containing AlH3, fatty acids and transition metal salts preferably includes the following steps: dissolving fatty acids and transition metal salts in a solvent, and then adding AlH3.

[0022] In step (2), the propellant oxidant may be one or more of ammonium perchlorate (AP), ammonium dinitramide (ADN) and cyclotetramethylenetetranitramine (HMX), for example, ammonium perchlorate.

[0023] In step (2), the mass ratio of AlH3@MSA to the propellant oxidant is preferably (0.5-5):1, more preferably (1-3):1, for example 1:1, 2:1, 2.3:1 or 2.5:1. This mass ratio affects the oxygen balance and energy characteristics of the core-shell coated energetic composite material. Excessive content of the propellant oxidant will reduce the overall energy, while insufficient content will result in incomplete oxidation.

[0024] In step (2), before the spray drying is carried out, the mixture of AlH3@MSA and propellant oxidant is generally prepared into a slurry.

[0025] The solvent in the slurry can be one or more of deionized water, ethanol, and ethyl acetate, preferably deionized water and / or ethanol. The mass concentration of AlH3@MSA in the slurry can be 0.01-0.3 g / mL, for example, 0.03 g / mL, 0.05 g / mL, 0.07 g / mL, 0.08 g / mL, 0.1 g / mL, 0.15 g / mL, or 0.2 g / mL.

[0026] The preparation method of the slurry can be conventional in the art and generally includes the following steps: dispersing the AlH3@MSA and the propellant in a solvent with an oxidant and mixing them evenly.

[0027] Prior to spray drying, the slurry is preferably subjected to ultrasonic dispersion or high-speed shear dispersion to ensure uniform distribution of AlH3@MSA and propellant oxidant in the suspension. The ultrasonic dispersion time can be 5-30 min; the shear dispersion rate can be 5000-15000 r / min.

[0028] In step (2), the inlet air temperature of the spray drying process can be 100-180℃, preferably 120-160℃, for example 120℃, 130℃, 140℃, 150℃ or 160℃; the outlet air temperature of the spray drying process can be 60-110℃, preferably 70-100℃, for example 80℃ or 90℃; the feed rate of the spray drying process can be 5-20 mL / min, preferably 8-15 mL / min, for example 10 mL / min; the atomization pressure of the spray drying process can be 0.1-0.5 MPa, preferably 0.2-0.4 MPa, for example 0.3 MPa; the diameter of the nozzle used in the spray drying process can be 1-5 mm, for example 2 mm or 3 mm. By controlling the parameters of the spray drying process, the particle size, morphology and coating uniformity of the composite particles can be adjusted.

[0029] In some preferred embodiments, the method for preparing the core-shell coated energetic composite material includes the following steps:

[0030] (1) Stearic acid and transition metal salt are dissolved in an ethanol-water mixed solvent, AlH3 particles are added, and the mixture is reacted at 25-60℃ for 30-90 min to obtain AlH3@MSA; wherein, the mass ratio of the fatty acid salt generated in the reaction system to the AlH3 is (1-10):100.

[0031] (2) The AlH3@MSA and ammonium perchlorate are dispersed in deionized water at a mass ratio of (1-3):1. After mixing evenly, spray drying is carried out with an inlet air temperature of 120-160℃, an outlet air temperature of 70-100℃, a feed rate of 8-15 mL / min, and an atomization pressure of 0.2-0.4 MPa to obtain a core-shell coated energetic composite material.

[0032] The present invention also provides a core-shell coated energetic composite material prepared by the preparation method described above.

[0033] The present invention also provides a core-shell coated energetic composite material having a core-shell structure, comprising a core, a first coating layer, and a second coating layer from the inside out; the core is AlH3, the first coating layer is a transition metal ester, and the second coating layer is an oxidant for propellants.

[0034] In this invention, the particle size of the core-shell coated energetic composite material particles can be 15-40 μm, preferably 20-30 μm.

[0035] In this invention, the thickness of the first coating layer can be 10-100 nm. The thickness of the second coating layer can be 300-500 nm.

[0036] In this invention, the transition metal fatty acid salt is generated by the reaction of a fatty acid and a transition metal salt. The types and amounts of the fatty acid and the transition metal salt are as described above. When the fatty acid is stearic acid and the transition metal salt is an iron salt, the fatty acid salt is iron stearate; when the fatty acid is stearic acid and the transition metal salt is a cobalt salt, the fatty acid salt is cobalt stearate; when the fatty acid is stearic acid and the transition metal salt is a copper salt, the fatty acid salt is copper stearate.

[0037] In this invention, the type of oxidant used in the propellant is as described above.

[0038] The present invention also provides the application of the core-shell coated energetic composite material as described above in solid propellants, explosives or pyrotechnics.

[0039] In this invention, when applied to solid propellants, explosives, or pyrotechnics, the core-shell coated energetic composite material generally serves as an energetic material. When applied to solid propellants, the core-shell coated energetic composite material can serve as a high-energy fuel and combustion performance modifier, providing both high energy output and improved combustion characteristics through catalytic oxidant decomposition.

[0040] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0041] The reagents and raw materials used in this invention are all commercially available.

[0042] The positive and progressive effects of this invention are as follows:

[0043] (1) The preparation method of the present invention is simple, the reaction conditions are mild, and the combination of in-situ synthesis and spray drying technology makes it easy to carry out continuous production, with low cost, and suitable for large-scale production;

[0044] (2) The core-shell coated energetic composite material prepared by this invention has excellent stability and can effectively improve the initial decomposition temperature and decomposition activation energy; when MSA is a stearate coating layer, its initial decomposition temperature can be increased by 2-5℃ and its decomposition activation energy can be increased by 10-35 kJ·mol. -1 ;

[0045] (3) Transition metal ions in fatty acids (such as Co) 2+It has a catalytic effect on the decomposition of oxidants, which can effectively improve the ignition and combustion performance of composite materials; when the oxidant is ammonium perchlorate (AP), it can reduce the high temperature decomposition peak of AP by 50-80℃ and the low temperature decomposition peak by 40-60℃.

[0046] (4) Compared with simple mechanical mixtures, the core-shell coating structure of the present invention makes the oxidant and AlH3 more closely in contact, the heat of reaction can be increased by 30-60%, the combustion is more complete, the particle size of the condensed phase combustion products is smaller and the distribution is narrower, and the combustion efficiency is significantly improved. Attached Figure Description

[0047] Figure 1 SEM and EDS images of AlH3@MSA and the original sample of the metal stearate-coated AlH3 intermediate prepared in Examples 1-3;

[0048] Figure 2 SEM and EDS images of the core-shell type AHMPs energetic composite particles prepared in Examples 1-3;

[0049] Figure 3 The TG-DSC curves of AlH3@MSA and the original sample of the metal stearate-coated AlH3 intermediate prepared in Examples 1-3 are shown.

[0050] Figure 4 The TG-DSC curves are for the core-shell type AHMPs energetic composite particles prepared in Examples 1-3 and pure AP.

[0051] Figure 5 The reaction heat change curves of the core-shell type AHMPs energetic composite particles and AlH3 / AP mechanical mixtures prepared in Examples 1-3 are shown. Detailed Implementation

[0052] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0053] Example 1

[0054] Step 1: Stearic acid (≥99%, Merck Sigma-Aldrich) and cobalt nitrate hexahydrate (Co(NO3)2·6H2O) (≥98%, Sinopharm Group Co., Ltd.) were dissolved in 1000 mL of ethanol-water mixed solvent (volume ratio 1:1) at a molar ratio of 2:1. The molar concentration of stearic acid was 2 mol / L. Then, AlH3 particles were added (the mass ratio of AlH3 to the theoretically generated cobalt stearate was 20:1). The mixture was stirred at 500 rpm for 60 min in a 40 °C water bath. After the reaction was completed, the mixture was filtered, washed three times with deionized water, and dried under vacuum at 50 °C for 6 h to obtain AlH3@CoSA2 (AlH3 coated with cobalt stearate).

[0055] Step 2: Disperse the above AlH3@CoSA2 and ammonium perchlorate (i.e. AP, Class III, Henan Nayu Co., Ltd.) in 100 mL of deionized water at a mass ratio of 7:3 (total mass 10g). The mass concentration of AlH3@CoSA2 is 0.07g / mL. Disperse by ultrasonication for 10 min to obtain a uniform suspension.

[0056] Step 3: The above suspension was spray-dried at an inlet air temperature of 150℃, an outlet air temperature of 80℃, a feed rate of 10mL / min, a nozzle diameter of 2 mm, and an atomization pressure of 0.3 MPa. The dried product was collected to obtain core-shell coated AlH3@CoSA2@AP energetic composite particles (denoted as AHMPs-Co). Based on the AlH3 feed amount, the product yield was 82.5% (composite particle mass / AlH3 feed amount). TG-DSC testing (NETZSCH STA449-F5) showed that compared to pure AlH3, the initial decomposition temperature of AlH3 in AHMPs-Co increased by 4.5℃, and the decomposition activation energy increased by 32.6 kJ·mol⁻¹. -1 The high-temperature decomposition peak of AP decreased by approximately 80.8 °C, and the low-temperature decomposition peak decreased by approximately 52.2 °C.

[0057] Example 2

[0058] Step 1: Except for replacing cobalt nitrate hexahydrate with ferric nitrate hexahydrate (Fe(NO3)3·9H2O) (≥98%, Sinopharm Group Co., Ltd.) and adding stearic acid and ferric nitrate hexahydrate in a molar ratio of 3:1, the other operations and conditions are the same as in Step 1 of Example 1, to obtain AlH3@FeSA3 (AlH3 coated with ferric stearate).

[0059] Step 2: Same as Step 2 in Example 1;

[0060] Step 3: Same as Step 3 in Example 1; core-shell coated AlH3@FeSA3@AP energetic composite particles (denoted as AHMPs-Fe) were obtained. Based on the AlH3 feed amount, the product yield was 80.8%. TG-DSC testing showed that, compared to pure AlH3, the initial decomposition temperature of AlH3 in AHMPs-Fe increased by 2.0 ℃, and the decomposition activation energy increased by 20.2 kJ·mol⁻¹. -1 .

[0061] Example 3

[0062] Step 1: Except for replacing cobalt nitrate hexahydrate with copper nitrate trihydrate (Cu(NO3)2·3H2O) (≥98%, Sinopharm Group Co., Ltd.) and adding stearic acid and copper nitrate hexahydrate in a molar ratio of 2:1, the other operations and conditions are the same as in Step 1 of Example 1, to obtain AlH3@CuSA2 (AlH3 coated with copper stearate).

[0063] Step 2: Same as Step 2 in Example 1;

[0064] Step 3: Same as Step 3 in Example 1; core-shell coated AlH3@CuSA2@AP energetic composite particles (denoted as AHMPs-Cu) were obtained. Based on the AlH3 feed amount, the product yield was 87.2%. TG-DSC testing showed that, compared to pure AlH3, the initial decomposition temperature of AlH3 in AHMPs-Cu increased by 3.0 ℃, and the decomposition activation energy increased by 11.2 kJ·mol⁻¹. -1 .

[0065] Comparative Example 1

[0066] Pure AlH3 raw material (uncoated). TG-DSC analysis showed an initial decomposition temperature of 163.0 ℃ and an activation energy of 79.6 kJ·mol⁻¹. -1 .

[0067] Comparative Example 2

[0068] AlH3 and AP (mass ratio 7:3) were mixed uniformly by simple mechanical grinding to obtain a physical mixture (AlH3 / AP). Oxygen bomb calorimetry testing showed that its heat of reaction was 4009 J / g, and the condensed phase combustion products had a large particle size and wide distribution.

[0069] Effect Example

[0070] (1) Morphological and structural characterization

[0071] Figure 1 The images show the SEM and EDS images of the metal stearate-coated AlH3 intermediate AlH3 prepared in Examples 1-3 and the original AlH3 sample, based on... Figure 1It was found that compared with pure AlH3, the surfaces of AlH3@FeSA3, AlH3@CoSA2, and AlH3@CuSA2 became rougher, with particles present on the surface, forming a coating layer on the AlH3 surface. EDS characterization of the elements present on the surface of the composite particles revealed a uniform distribution of Al, O, Fe, Co, and Cu, indicating that the three stearates were successfully coated on the AlH3 particle surface. The hydrophilicity and hydrophobicity of the samples before and after coating were tested using a contact angle meter (JY-82C). The water contact angle of pure AlH3 was 51.87°, exhibiting hydrophilic properties. The contact angle was improved after stearate coating; the contact angles of AlH3@MSA-Fe, Co, and Cu were 66.08°, 72.16°, and 117.94°, respectively, indicating that the coated samples possessed significant hydrophobic stability.

[0072] Figure 2 The images shown are SEM and EDS images of the final product, core-shell type AHMPs energetic composite particles, prepared in Examples 1-3. Figure 2 It can be seen that the uniformly coated AP layer can cover the original defects and pores of AlH3 particles, and the EDS results also show that the particle surface is uniformly coated with AP.

[0073] (2) Study on thermal decomposition characteristics

[0074] The Friedman method can obtain the trend of the activation energy of the sample with the conversion rate (α) and can avoid the influence of the model on the calculation results, and is widely used in kinetic calculations. The relationship between the rate constant and temperature in this method can be replaced by the Arrhenius equation, as shown in equation (1):

[0075]

[0076] Taking the logarithm of both sides of the above equation, we get equation (2):

[0077]

[0078] Substituting dt=dT / β into the above equation, we get equation (3):

[0079]

[0080] Under the assumption of constant conversion rate, the function f(α) can be regarded as a specific constant. In this case, ln(dα / dt) has a linear relationship with 1 / T, and its slope is -E. a / R.

[0081] Figure 3The TG-DSC curves show the intermediate AlH3@MSA and the original AlH3 sample prepared in Examples 1-3 for coating AlH3 with metal stearates. Compared with the original AlH3 sample, the initial decomposition temperatures of the stearate-coated samples (AlH3@FeSA3, AlH3@CoSA2, AlH3@CuSA2) increased by 2.0, 4.5, and 3.0 °C, respectively, indicating a slower decomposition process and an increased decomposition temperature range. Among the three stearates, the endothermic peak temperatures of AlH3@FeSA3, AlH3@CoSA2, and AlH3@CuSA2 increased by 1.9, 3.8, and 7.1 °C, respectively, indicating that stearate coating can increase the stability of AlH3. The weight loss and endothermic data show that stearate coating has little effect on the hydrogen content of the samples, making it an ideal coating material.

[0082] Figure 4 The TG-DSC curves show the changes in the energy of the core-shell AHMPs energetic composite particles prepared in Examples 1-3 and pure AP. According to... Figure 4 The temperatures at which the maximum weight loss rate occurs during AP decomposition are 310.2 and 421.8 °C, respectively. In the AHMPs composite particles, AP decomposition is accelerated due to the catalytic effect of metal ions, and the decomposition process changes from two steps to one. The temperatures at which the maximum weight loss rate occurs for the three composite particles (AHMPs-Fe, Co, Cu) are 351.2 °C, 334.3 °C, and 335.2 °C, respectively, with peak temperatures decreasing by 70.6, 87.5, and 86.6 °C. DSC curves show that compared to the high and low temperature decomposition peak temperatures of pure AP (314.7 and 427.7 °C), the transition metals in the composite particles can catalyze AP decomposition. The low-temperature decomposition peak temperatures of the AHMPs-Fe, Co, and Cu composite particles are 262.5, 259.5, and 273.2 °C, respectively, while the high-temperature decomposition peak temperatures are 359.3, 346.9, and 371.2 °C, respectively, indicating a significantly accelerated decomposition process and a substantial decrease in decomposition peak temperatures. By analyzing the changes in peak temperature, it was found that AHMPs-Co exhibits the strongest catalytic effect on AP, with the largest decrease in peak temperature.

[0083] (3) Study on heat of reaction

[0084] The reaction heat of AHMPs composite particles containing different transition metals in argon gas was measured using an oxygen bomb calorimeter (ZDHW-HN7000C). The specific process is as follows: (1) Weigh about 0.5 g of the sample and place it in a stainless steel crucible. Place it in a stainless steel oxygen bomb cylinder, install a nickel-chromium ignition wire on the support electrode, and then seal the oxygen bomb cylinder; (2) Fill the oxygen bomb cylinder with 3 MPa of argon gas. Repeat the filling / exhausting process three times to ensure that the internal air is completely removed; (3) After calibrating the equipment with benzoic acid, start the measurement to obtain the reaction heat value of the sample. Each sample is measured 3 times and the average value is taken.

[0085] Figure 5 The reaction heat curves are for the core-shell type AHMPs energetic composite particles prepared in Examples 1-3 and the AlH3 / AP mechanical mixture prepared in Comparative Example 2. Based on... Figure 5 It can be seen that the heat of reaction of the mechanically mixed sample is 4009 J / g. -1 The heats of reaction for AHMPs-Fe, Co, and Cu are 5103, 6387, and 4584 J, respectively. -1 The results showed that stearate coating containing transition metals has a catalytic effect, increasing reaction efficiency and raising reaction heat.

[0086] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A method for preparing a core-shell coated energetic composite material, characterized in that, Includes the following steps: (1) A mixture containing AlH3, fatty acids and transition metal salts is reacted to form a fatty acid coating layer on the surface of AlH3 to obtain AlH3@MSA; (2) The mixture of AlH3@MSA and propellant with oxidant is spray-dried to obtain the core-shell coated energetic composite material.

2. The method for preparing the core-shell coated energetic composite material as described in claim 1, characterized in that, Step (1) satisfies one or more of the following conditions: (1) The fatty acid is a long-chain fatty acid with more than 12 carbon atoms, preferably a long-chain fatty acid with 13-20 carbon atoms, such as stearic acid; (2) The transition metal salt is one or more of iron salt, cobalt salt and copper salt; (3) The solvent in the mixture is a solvent that can promote the dissolution of fatty acids and the dispersion of AlH3, such as deionized water and / or ethanol.

3. The method for preparing the core-shell coated energetic composite material as described in claim 2, characterized in that, The iron salt is one or more of ferrous sulfate, ferrous chloride, ferrous nitrate, ferric sulfate, ferric chloride, and ferric nitrate; The cobalt salt is one or more of cobalt sulfate, cobalt chloride, and cobalt nitrate; The copper salt is one or more of copper sulfate, copper chloride, and copper nitrate; When the solvent in the mixture is an ethanol-water mixture, the volume ratio of ethanol to water is (0.5-3):

1.

4. The method for preparing the core-shell coated energetic composite material as described in claim 1, characterized in that, Step (1) satisfies one or more of the following conditions: (1) The molar ratio of the fatty acid to the metal ion in the transition metal salt is (1-5):1, preferably (1.5-3.5):1; (2) The mass ratio of the fatty acid salt generated in the reaction system to the AlH3 is (1-20):100, preferably (1-10):100; (3) In the mixture, the molar concentration of the fatty acid is 0.5-10 mol / L.

5. The method for preparing the core-shell coated energetic composite material as described in claim 1, characterized in that, In step (1), the reaction temperature is 25-60℃, preferably 30-50℃; And / or, in step (1), the reaction time is 30-120 min, preferably 30-90 min.

6. The method for preparing the core-shell coated energetic composite material as described in claim 1, characterized in that, Step (2) satisfies one or more of the following conditions: (1) The oxidant used in the propellant is one or more of ammonium perchlorate, ammonium dinitramide, and cyclotetramethylenetetranitramine; (2) The mass ratio of AlH3@MSA to the oxidant for propellant is (0.5-5):1, preferably (1-3):1; (3) Before performing the spray drying, the mixture of AlH3@MSA and propellant oxidant is first prepared into a slurry.

7. The method for preparing the core-shell coated energetic composite material as described in claim 1, characterized in that, The spray drying satisfies one or more of the following conditions: (1) The inlet air temperature of the spray dryer is 100-180℃, preferably 120-160℃; (2) The outlet air temperature of the spray dryer is 60-110℃, preferably 70-100℃; (3) The feed rate of the spray drying is 5-20 mL / min, preferably 8-15 mL / min; (4) The atomization pressure of the spray drying is 0.1-0.5 MPa, preferably 0.2-0.4 MPa.

8. A core-shell coated energetic composite material prepared by the method for preparing a core-shell coated energetic composite material as described in any one of claims 1-7.

9. A core-shell coated energetic composite material, characterized in that, It has a core-shell structure, consisting of a core, a first coating layer, and a second coating layer from the inside out; the core is AlH3, the first coating layer is a transition metal ester, and the second coating layer is an oxidant for propellant.

10. The use of a core-shell coated energetic composite material as described in claim 8 or 9 in solid propellants, explosives or pyrotechnics.

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