Method for preparing micro-nano high-sphericity HMX explosive crystal and regulating and controlling granularity of micro-nano high-sphericity HMX explosive crystal

Abstract

The invention relates to the technical field of energetic material preparation, in particular to a micro-nano high-sphericity HMX explosive crystal preparation and granularity regulation and control method, which comprises the following steps: (1) heating in a water bath kettle to completely dissolve a raw material HMX in a solvent, adding a crystal form control agent to form an explosive solution, and heating another weighed solvent in a water bath; (2) putting a non-solvent into an Easy Max reaction kettle, setting corresponding parameters, and slowly adding the explosive solution and the solvent into the non-solvent to separate out HMX explosive crystals, (3) filtering and washing, putting the HMX explosive into the non-solvent, and carrying out ultrasonic treatment to obtain a suspension; (4) filtering, washing and drying to obtain high-sphericity HMX explosive crystals; the HMX crystal prepared by the preparation method disclosed by the invention is uniform in particle size, the particle size can reach micro-nano, the sphericity of the crystal is relatively good, the impact sensitivity is greatly reduced, and the related preparation process is high in safety, simple and easy to control.

Description

Technical Field

[0001] This invention relates to the field of energetic materials preparation technology, specifically to a method for preparing and controlling the particle size of micro / nano high sphericity HMX explosive crystals. Background Technology

[0002] 1,3,5,7-Tetranitro-1,3,5,7-tetrazocin (HMX), also known as cyclotetramethylenetetranitramine, is used in modern military weapons as the best-performing single-element high explosive due to its high detonation velocity, good thermal stability and detonation performance.

[0003] In the field of energetic materials research, scientists are dedicated to gaining a deeper understanding of crystal growth mechanisms and morphological evolution processes through advanced synthesis techniques and precise characterization methods. These studies not only reveal the intrinsic relationship between crystal morphology and properties but also provide a theoretical basis for designing novel energetic materials. In practical applications, energetic materials, as special chemical substances, have a decisive impact on the safety and application performance of products due to their crystal morphology, structure, and particle size. Precise control and optimization of structural morphology are crucial for improving the processing and safety performance of energetic materials; therefore, regulating the structural morphology of energetic materials to reduce their sensitivity and improve safety performance is a current research hotspot.

[0004] In terms of morphology, micro / nano HMX combines the structural stability of micron-sized HMX with the low sensitivity of nano-sized HMX, effectively reducing mechanical sensitivity while maintaining high energy density and thermal stability. Compared to single micron or nano-sized HMX, micro / nano HMX achieves comprehensive optimization in energy, safety, and process controllability, exhibiting superior application potential. In recent years, spherical crystals have attracted widespread attention from researchers in the field of energetic material crystallization due to their unique product performance. Compared to traditional needle-like, plate-like, and rod-like crystals, spherical crystals have significant advantages: their smooth surface effectively reduces friction between solid particles, decreasing the possibility of hot spot formation and thus significantly reducing product sensitivity. Furthermore, spherical crystals exhibit excellent flowability, high packing density, and perfect crystal morphology, making them an ideal target for crystal morphology control. Therefore, in the solution crystallization process of energetic materials, a suitable particle size and high sphericity can endow the material with good flowability and filling performance, significantly improving charge density and interfacial bonding, meeting the application requirements of high-energy, low-sensitivity charge systems.

[0005] Currently, the main methods for preparing spherical HMX include recrystallization, spray drying, microemulsion, mechanical ball milling, and supercritical fluid technology. Among these, the solvent-non-solvent method has become the mainstream preparation method due to its advantages such as controllable nucleation, uniform particle size distribution, tunable morphology, and low cost. However, HMX crystals obtained by traditional processes are mostly blocky or plate-like, with sharp edges and poor structural density, making it difficult to meet the requirements of high-safety charge loading. In recent years, physical field-assisted crystallization technology has provided a new approach for the controllable regulation of crystal morphology and properties by precisely intervening in the crystal nucleation and growth process through external field energy. In particular, ultrasonic technology, utilizing the strong cavitation effect in the liquid phase system, can significantly improve crystal quality and safety performance without changing the chemical composition. However, there is a mismatch between the inherent crystallization characteristics of HMX and ultrasonic energy regulation, resulting in difficulty in controlling particle size distribution, increased crystal defects, and insufficient process stability. Summary of the Invention

[0006] The purpose of this invention is to precisely control the morphology of HMX explosive particles, simplify the process, effectively reduce friction between solid particles, decrease hot spot formation, and significantly reduce product sensitivity. This invention provides a method for preparing and controlling the particle size of micro / nano-sized high-sphericity HMX explosive crystals. This invention achieves morphology control and modification of HMX crystals through two stages: solvent-non-solvent and ultrasound-assisted Easy Max control. This synergistic intervention in HMX nucleation and growth behavior successfully prepares HMX crystals with high sphericity, uniform particle size, low sensitivity, and stable processing, and also achieves controllable particle size. The structural morphology of the micro / nano-sized high-sphericity HMX explosive crystals reduces hot spot formation and optimizes its impact sensitivity, friction sensitivity, and other safety performance, giving HMX explosives more application potential. This invention provides a certain reference for methods to reduce the sensitivity of HMX explosives.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a method for preparing and controlling the particle size of micro / nano high sphericity HMX explosive crystals, comprising the following steps: (1) Preparation of HMX explosive solvent system Based on the physicochemical properties of HMX explosive, select a suitable solvent or non-solvent, place the non-solvent in the reaction vessel, and place the reaction vessel in Easy Max. (2) Easy Max precisely controls the crystal morphology of HMX explosives HMX explosive is completely dissolved in a solvent to form liquid A. Another weighed pure solvent without HMX is used as liquid B. Liquid A and liquid B are placed together in a water bath and heated. After the crystals are completely dissolved, liquid A and liquid B are dripped into the reaction vessel of step (1). The temperature and time in the reaction vessel are precisely controlled by Easy Max to make the crystals precipitate completely. Then the suspension is filtered and washed to obtain explosive crystals. (3) Ultrasonic-assisted preparation of high sphericity HMX explosive crystals The explosive crystals obtained in step (2) are placed in a non-solvent and subjected to probe-type ultrasound, with the ultrasound interval, ultrasound time and power controlled. (4) Filtration and drying of high sphericity HMX explosive crystals The suspension prepared in step (3) was filtered, washed and dried to obtain HMX explosive crystals with high sphericity.

[0008] The core technology of this invention is to prepare micro-nano high sphericity HMX crystals with adjustable particle size by using Easy Max to precisely control antisolvent crystallization combined with ultrasonic treatment technology from powdered HMX raw materials.

[0009] The technical principle employed in this invention is primarily based on recrystallization and ultrasonic technology. Ultrasonic cavitation generates cavitation bubbles, which, in a solid-liquid mixture, deform and collapse due to the asymmetric environment, forming microjets that deform the solid surface. Simultaneously, this induces collisions between particles, and the interaction between shock waves and solid particles causes acoustic fracturing. These particle collisions and acoustic fracturing affect the average particle size and size distribution by reducing the size of the existing crystals and generating secondary nucleation sites.

[0010] As a further limitation of the technical solution of the present invention, the solvent selected in step (1) is at least one of dimethyl sulfoxide, N-methylpyrrolidone, cyclohexanone, acetone, γ-butyrolactone and N,N-dimethylformamide; the non-solvent is at least one of water, ethanol and ethyl acetate.

[0011] As a further limitation of the technical solution of the present invention, the reactor in step (2) is a jacketed reactor, the temperature of the material in the reactor is controlled by EasyMax, a peristaltic pump is used to connect the water bath and the reactor, and the reactor container is flat-bottomed cylindrical or spherical-bottomed cylindrical.

[0012] As a further limitation of the technical solution of the present invention, the temperature range of Easy Max temperature control in step (2) is required to be 10-20 ℃; the stirring rate range is 450-600 r·min. -1 The stirring time ranges from 60 to 180 minutes, and the temperature range of the water bath is 30 to 60 ℃.

[0013] As a further limitation of the technical solution of the present invention, in step (2), the mass ratio of HMX explosive to solvent in liquid A is 4:33; in step (2), the mass ratio of solvent in liquid A to solvent in liquid B is 11:69; in step (2), the total mass of solvent to volume ratio of non-solvent in step (1) is 1 g:2 mL.

[0014] As a further limitation of the technical solution of the present invention, the ultrasonic interval time range in step (3) is 1-5 s, the ultrasonic time range is 0-30 min, and the ultrasonic power range is 195-520 W.

[0015] As a further limitation of the technical solution of the present invention, the filtration method in step (4) is vacuum filtration or centrifugal filtration, and the drying method is water bath drying, vacuum drying or freeze drying.

[0016] As a further limitation of the technical solution of the present invention, step (4) washing is to rinse the explosive crystals with a non-solvent and wash the solvent.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention enables the preparation of high sphericity HMX explosives with different particle sizes by adjusting solvent ratio, solution temperature, stirring rate, etc., and realizes the preparation and particle size control of micro-nano high sphericity HMX explosive crystals.

[0018] Ultrasonic technology, as the final step in controlling the morphology and particle size of HMX crystals, not only accelerates the solvent etching process but also effectively breaks up crystal agglomerations, offering significant advantages such as high efficiency, energy saving, and ease of operation.

[0019] By combining antisolvent crystallization with ultrasonic technology, micro- and nano-sized high-sphericity HMX crystals can be prepared. This method is not limited by the crystal structure and morphology of HMX raw materials and can stably obtain the target crystals in a relatively short time.

[0020] The micro / nano high sphericity HMX explosive crystals prepared by the method of this invention reduce the formation of hot spots and optimize their safety performance such as impact sensitivity and friction sensitivity, giving HMX explosives more application potential. Attached Figure Description

[0021] Figure 1 This is a scanning electron microscope image of the HMX crystal raw material used in this invention.

[0022] Figure 2 This is a scanning electron microscope image of the HMX crystal obtained before ultrasonic treatment in Example 1.

[0023] Figure 3 Scanning electron microscope image of the high sphericity HMX crystal prepared in Example 1.

[0024] Figure 4 Scanning electron microscope image of the high sphericity HMX crystal prepared in Example 2.

[0025] Figure 5 Scanning electron microscope image of the high sphericity HMX crystal prepared in Example 3.

[0026] Figure 6 Scanning electron microscope image of the high sphericity HMX crystal prepared in Example 4.

[0027] Figure 7 This is a particle size distribution diagram of the HMX crystal raw material used in this invention.

[0028] Figure 8 The particle size distribution diagram is shown for the high sphericity HMX crystal prepared in Example 1.

[0029] Figure 9 The particle size distribution diagram is shown for the high sphericity HMX crystal prepared in Example 2.

[0030] Figure 10 The particle size distribution diagram is shown for the high sphericity HMX crystal prepared in Example 3.

[0031] Figure 11 The particle size distribution diagram is shown for the high sphericity HMX crystal prepared in Example 4.

[0032] Figure 12 Impact sensitivity and friction sensitivity diagrams of the HMX crystal obtained before ultrasonic treatment in Example 1 and the high sphericity HMX prepared in Example 1. Detailed Implementation

[0033] The present invention will be further described below with reference to specific embodiments. Example 1

[0034] A method for preparing and controlling the particle size of micro / nano high-sphericity HMX explosive crystals includes the following steps: (1) Mix 0.5 g of HMX explosive crystals with 4.125 g of dimethyl sulfoxide, and place the mixture with another 25.875 g of dimethyl sulfoxide in a water bath and heat to 60 °C to completely dissolve the explosive in the dimethyl sulfoxide, thus preparing an explosive solution. Place 60 ml of deionized water in a spherical-bottom cylindrical reactor in an Easy Max container and heat at 600 r·min. -1 The temperature of the non-solvent in the reactor was controlled at 10 °C under the specified rotation speed. The explosive solution and solvent were added dropwise to the reactor sequentially at a rotation speed of 10 rpm, and the temperature was maintained at 600 rpm. -1 Stirring at a speed of 180 min yielded a suspension of HMX crystals.

[0035] (2) Take out the suspension and separate the solution from the crystal by vacuum filtration. Wash the crystal with deionized water three times. Add the washed crystal back into deionized water and sonicate at 520 W for 15 min at 1 s intervals to obtain HMX crystal suspension.

[0036] (3) Take out the suspension, filter and separate the solution and crystals by vacuum filtration, wash the crystals with deionized water, and put them into a freeze dryer to dry for 4 hours.

[0037] (4) The scanning electron microscope image of the unultrasonicated bulk crystal, as determined by experiments, is shown below. Figure 2 As shown. The crystal scanning electron microscope image after ultrasonic treatment is as follows. Figure 3 As shown, the HMX crystal is spherical, and its particle size was measured using a laser particle size analyzer. Figure 8 As shown, particle size distribution D 10 =0.796 mm, D 50 =4.630 mm, D 90 =8.280 mm. The particle size distribution of the HMX crystal raw material used is shown in the figure. Figure 7 As shown, the particle size distribution is D 10 =5.632 mm, D 50 =79.880 mm, D 90 =200.600 mm. Example 2

[0038] A method for preparing and controlling the particle size of micro / nano high-sphericity HMX explosive crystals includes the following steps: (1) Mix 0.5 g of HMX explosive crystals with 4.125 g of dimethyl sulfoxide, and place the mixture with another 25.875 g of dimethyl sulfoxide in a water bath and heat to 60 °C to completely dissolve the explosive in the dimethyl sulfoxide, thus preparing an explosive solution. Place 60 ml of deionized water in a spherical-bottom cylindrical reactor in an Easy Max container and heat at 600 r·min. -1 The temperature of the non-solvent in the reactor was controlled at 10 °C under the specified rotation speed. The explosive solution and solvent were added dropwise to the reactor sequentially at a rotation speed of 10 rpm, and the temperature was maintained at 600 rpm. -1 Stirring at a speed of 180 min yielded a suspension of HMX crystals.

[0039] (2) Take out the suspension and separate the solution from the crystal by vacuum filtration. Wash the crystal with deionized water three times. Add the washed crystal back into deionized water and sonicate at 520 W for 20 min at 2 s intervals to obtain HMX crystal suspension.

[0040] (3) Take out the suspension, filter and separate the solution and crystals by vacuum filtration, wash the crystals with deionized water, and put them into a freeze dryer to dry for 4 hours.

[0041] (4) The crystal scanning electron microscope image was determined experimentally as follows: Figure 4As shown, the HMX crystal is spherical. The particle size distribution, measured using a laser particle size analyzer, is as follows: Figure 9 As shown, particle size distribution D 10 =0.886 mm, D 50 =5.796 mm, D 90 =9.947 mm. Example 3

[0042] A method for preparing and controlling the particle size of micro / nano high-sphericity HMX explosive crystals includes the following steps: (1) Mix 0.5 g of HMX explosive crystals with 4.125 g of dimethyl sulfoxide, and place the mixture with another 25.875 g of dimethyl sulfoxide in a water bath and heat to 60 °C to completely dissolve the explosive in the dimethyl sulfoxide, thus preparing an explosive solution. Place 60 ml of deionized water in a spherical-bottom cylindrical reactor in an Easy Max container and heat at 600 r·min. -1 The temperature of the non-solvent in the reactor was controlled at 10 °C under the specified rotation speed. The explosive solution and solvent were added dropwise to the reactor sequentially at a rotation speed of 10 rpm, and the temperature was maintained at 600 rpm. -1 Stirring at a speed of 120 min yielded a suspension of HMX crystals.

[0043] (2) Take out the suspension and separate the solution from the crystal by vacuum filtration. Wash the crystal with deionized water three times. Add the washed crystal back into deionized water and sonicate at 195 W for 20 min at 1 s intervals to obtain HMX crystal suspension.

[0044] (3) Take out the suspension, filter and separate the solution and crystals by vacuum filtration, wash the crystals with deionized water, and put them into a freeze dryer to dry for 4 hours.

[0045] (4) The crystal scanning electron microscope image was determined experimentally as follows: Figure 5 As shown, the HMX crystal is spherical. The particle size distribution, measured using a laser particle size analyzer, is as follows: Figure 10 As shown, particle size distribution D 10 =1.127 mm, D 50 =7.634 mm, D 90 =13.110 mm. Example 4

[0046] A method for preparing and controlling the particle size of micro / nano high-sphericity HMX explosive crystals includes the following steps: (1) Mix 0.5 g of HMX explosive crystals with 4.125 g of dimethyl sulfoxide, and place the mixture with another 25.875 g of dimethyl sulfoxide in a water bath and heat to 60 °C to completely dissolve the explosive in the dimethyl sulfoxide, thus preparing an explosive solution. Place 60 ml of deionized water in a spherical-bottom cylindrical reactor in an Easy Max container and heat at 600 r·min. -1 The temperature of the non-solvent in the reactor was controlled at 10 °C under the specified rotation speed. The explosive solution and solvent were added dropwise to the reactor sequentially at a rotation speed of 10 rpm, and the temperature was maintained at 600 rpm. -1 Stirring at a speed of 120 min yielded a suspension of HMX crystals.

[0047] (2) Take out the suspension and separate the solution from the crystal by vacuum filtration. Wash the crystal with deionized water three times. Add the washed crystal back into deionized water and sonicate at 195 W for 20 min at 2 s intervals to obtain HMX crystal suspension.

[0048] (3) Take out the suspension, filter and separate the solution and crystals by vacuum filtration, wash the crystals with deionized water, and put them into a freeze dryer to dry for 4 hours.

[0049] (4) Experimental measurements showed that the crystal microscope images were as follows: Figure 6 As shown, the HMX crystal is spherical. The particle size distribution, measured using a laser particle size analyzer, is as follows: Figure 11 As shown, particle size distribution D 10 =2.260 mm, D 50 =9.418 mm, D 90 =18.350 mm.

Claims

1. A method for preparing and controlling the particle size of micro / nano high-sphericity HMX explosive crystals, characterized in that, Includes the following steps: (1) Preparation of HMX explosive solvent system Based on the physicochemical properties of HMX explosive, select a suitable solvent or non-solvent, place the non-solvent in the reaction vessel, and place the reaction vessel in Easy Max. (2) Easy Max precisely controls the crystal morphology of HMX explosives HMX explosive is completely dissolved in a solvent to form liquid A. Another weighed pure solvent without HMX is used as liquid B. Liquid A and liquid B are placed together in a water bath and heated. After the crystals are completely dissolved, liquid A and liquid B are dripped into the reaction vessel of step (1). The temperature and time in the reaction vessel are precisely controlled by Easy Max to make the crystals completely precipitate. Then the suspension is filtered and washed to obtain explosive crystals. (3) Ultrasonic-assisted preparation of high sphericity HMX explosive crystals The explosive crystals obtained in step (2) are placed in a non-solvent and subjected to probe-type ultrasound, with the ultrasound interval, ultrasound time and power controlled. (4) Filtration and drying of high sphericity HMX explosive crystals The suspension prepared in step (3) was filtered, washed and dried to obtain HMX explosive crystals with high sphericity.

2. The method for preparing and controlling the particle size of micro / nano high-sphericity HMX explosive crystals according to claim 1, characterized in that, The solvent selected in step (1) is at least one of dimethyl sulfoxide, N-methylpyrrolidone, cyclohexanone, acetone, γ-butyrolactone and N,N-dimethylformamide; the non-solvent is at least one of water, ethanol and ethyl acetate.

3. The method for preparing and controlling the particle size of micro / nano high-sphericity HMX explosive crystals according to claim 1, characterized in that, The reactor in step (2) is a jacketed reactor. The temperature of the material in the reactor is controlled by Easy Max. A peristaltic pump is used to connect the water bath and the reactor. The reactor container is flat-bottomed cylindrical or spherical-bottomed cylindrical.

4. The method for preparing and controlling the particle size of micro / nano high-sphericity HMX explosive crystals according to claim 1, characterized in that, The temperature range for Easy Max temperature control in step (2) is required to be 10-20 ℃; the stirring rate range is required to be 450-600 r·min. -1 The stirring time ranges from 60 to 180 minutes, and the temperature range of the water bath is 30 to 60 ℃.

5. The method for preparing and controlling the particle size of micro / nano high-sphericity HMX explosive crystals according to claim 1, characterized in that, In step (2), the mass ratio of HMX explosive to solvent in liquid A is 4:33; the mass ratio of solvent in liquid A to solvent in liquid B is 11:69; the total mass of solvent in step (2) is 1 g:2 mL to the volume ratio of non-solvent in step (1).

6. The method for preparing and controlling the particle size of micro / nano high-sphericity HMX explosive crystals according to claim 1, characterized in that, The ultrasonic interval time range in step (3) is 1-5 s, the ultrasonic time range is 0-30 min, and the ultrasonic power range is 195-520 W.

7. The method for preparing and controlling the particle size of micro / nano high-sphericity HMX explosive crystals according to claim 1, characterized in that, Step (4) uses vacuum filtration or centrifugal filtration for filtration and water bath drying, vacuum drying or freeze drying for drying.

8. The method for preparing and controlling the particle size of micro / nano high-sphericity HMX explosive crystals according to claim 1, characterized in that, Step (4) washing involves rinsing the explosive crystals with a non-solvent solution, using a washing solvent.

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