Preparation method of co-granular nitramine crystals based on interface enhancement passivation modification and co-granular nitramine crystals

Abstract

The present invention relates to a preparation method of co-granular nitramine crystals based on interface enhanced passivation modification and co-granular nitramine crystals, and relates to the technical field of energetic material passivation. The method uses typical high-energy-density nitramine oxidants HMX and CL-20 as passivation modification objects, adopts nano-sized and surface-functionalized passivated energetic crystals as passivation agents, and constructs based on strong intermolecular functional groups between crystal surfaces, using crystal assembly as a driving force to obtain densely structured co-granular crystals. This method can not only maintain the high energy density of the nitramine oxidant, but also effectively improve its safety.

Description

Technical Field

[0001] The invention belongs to the field of passivation modification of high-energy crystal materials, and relates to a preparation method of co-granular nitramine crystals based on interface enhanced passivation modification and co-granular nitramine crystals. Background Art

[0002] Solid propellant is an energetic composite material with specific properties. It is the power source of various devices such as missiles and spacecraft, and is crucial in the development of missile and aerospace technology. Breaking through the contradiction between high energy and low sensitivity of propellants is the key to meeting the long range and high safety of advanced tactical missile engines. It is necessary to focus on the research of high-energy material passivation technology to ensure its energy density while significantly reducing its sensitivity. The use of energetic binders (Energetic Materials, 2019, 27(1):9-13), energetic plasticizers (Journal of Explosives and Propellants, 2022, 45(2):154-163; Energetic Materials, 2019, 27(1):9-13; Chemical Propellants and Polymer Materials, 2021, 19(5):21-26), insensitive energetic materials (Energetic Materials, 2020, 28(8):740-748) or passivation modification of high-energy fillers are all widely used technical approaches. High-energy oxidizers account for a large proportion of the propellant formula and are a key factor affecting its energy performance and safety performance. Therefore, the development of new high-energy insensitive materials is the main technical approach to promote the substantial development of high-energy insensitive propellants. However, for energetic materials, energy and sensitivity are often a pair of contradictions. Therefore, the research on improving the performance of energetic materials in all aspects has become a current research hotspot (Energetic Materials, 2020, 28(8): 798-809.), effectively improving the safety of energetic materials without losing energy levels.

[0003] With the development of structural research and theoretical calculation of energetic materials, more new energetic materials have been successfully synthesized and applied to propellants (Journal of Materials Chemistry, 2010, 20 (15): 2999-3005). However, due to various objective factors such as technical conditions and external environment, the development of the energy level of new high-energy insensitive materials is at a certain bottleneck period. Therefore, it is more practical to use existing high-energy materials as a basis and modify them through a series of technical means to make them insensitive. On the one hand, researchers start from improving crystal quality and reducing defects on the surface and inside of crystals to reduce the probability of hot spots. On the other hand, they slow down the hot spot transmission rate through technical means such as surface coating, doping, and eutectic. However, the existing technologies all have similar problems, that is, the energy performance is reduced while improving safety. The goal of maintaining the safety of explosives while increasing energy has not yet been achieved. How to reasonably and properly solve the contradiction between safety (insensitivity) and high destructiveness (high energy) of energetic materials and find new methods for preparing high-energy insensitive materials has become one of the important topics of international research today. Therefore, it is urgent to conduct research on the energy / safety synergistic enhancement mechanism of high-energy insensitive materials and explore universal preparation methods for high-energy insensitive materials.

[0004] Energetic co-particles are a form of composite crystals between energetic molecular eutectics and doped desensitization. They are cross-stacked and arranged at the nanoparticle scale to form a dense structure, achieving excellent desensitization function, and the adjustable mass ratio of nitramine oxidant and insensitive energetic nanocrystals provides the possibility of balancing energy performance and safety performance. This project adopts an interface assembly strategy, combining the advantages of three passivation processes of energetic materials, "nano-ization", "coating" and "local eutectic", to effectively combine nitramine oxidant and insensitive energetic nanocrystals at the interface molecular level, thus realizing the co-particle design of "nitramine oxidant / interface layer / insensitive nanocrystal". Cyclotetramethylenetetranitramine (HMX) and hexanitrohexaazaisowurtzitane (CL-20), typical high-energy-density nitramine oxidants, were used as the passivation modification objects. Co-particle assembly was performed with surface-functionalized passivation nanocrystals triaminotrinitrobenzene (TATB), 1,1-diamino-2,2-dinitroethylene (FOX-7) and 1-oxy-2,6-diamino-3,5-dinitropyrazine (LLM-105). This method provides a new idea for balancing energy performance and safety performance, and is expected to provide broader application prospects for the development of energetic materials. Summary of the invention

[0005] Technical issues to be solved

[0006] In order to avoid the shortcomings of the prior art, the present invention proposes a preparation method of co-particle nitramine crystals based on interface enhanced passivation modification and co-particle nitramine crystals, selects typical high-energy nitramine oxidants HMX and CL-20 as passivation modification objects, uses passivated energetic crystals as additives, and carries out serial design and preparation of "nitramine oxidant / interface layer / passive nanocrystals", providing new ideas for the development of high-energy passivated crystals.

[0007] Technical Solution

[0008] A method for preparing co-granular nitramine crystals based on interface enhancement passivation modification, characterized in that the steps are as follows:

[0009] Step 1: nano-processing the insensitive energetic crystals by wet ball milling to obtain insensitive energetic nanocrystals;

[0010] Step 2: coating the surface of the insensitive energetic nanocrystal with a layer of polydopamine by in-situ self-polymerization to obtain an insensitive energetic crystal;

[0011] Step 3: adding the insensitive energetic crystals to a precursor solution and dispersing by ultrasonication to obtain a dispersed suspension; the precursor solution is obtained by dissolving a nitramine oxidant in an organic solvent;

[0012] Step 4: spray-dry the dispersed suspension to obtain "nitramine oxidant / interface layer / insensitive nanocrystals" co-particles.

[0013] The ultrasonic dispersion time in step 3 is 30 min.

[0014] The particle size of the insensitive energetic crystals after nano-sizing in step 1 is 200 to 500 nm.

[0015] The coating time of the insensitive energetic crystals in step 2 is 2 hours, and the thickness of the coated polydopamine is 3-5 nm.

[0016] The organic solvent in step 3 is dimethyl sulfoxide or ethyl acetate.

[0017] The temperature of the precursor solution is 30-50° C., and the concentration of the nitramine oxidant in the precursor solution is 0.15-0.5 g / ml.

[0018] The inlet temperature of the spray drying in step 4 is 60-180° C., and the feed rate is 3-6 ml / min.

[0019] The interface enhanced passivation modified co-granular nitramine crystal obtained by the preparation method is characterized in that it comprises the following components in terms of mass percentage: 90% to 99% nitramine oxidant and 1% to 10% passivation energetic crystal.

[0020] The nitramine oxidant is octogen HMX or hexanitrohexaazaisowurtzitane CL-20.

[0021] The insensitive energetic crystal is triaminotrinitrobenzene TATB, 1-oxy-2,6-diamino-3,5-dinitropyrazine LLM-105 or 1,1-diamino-2,2-dinitroethylene FOX-7.

[0022] Beneficial Effects

[0023] The invention provides a preparation method of co-granular nitramine crystals based on interface enhanced passivation modification and co-granular nitramine crystals, which relate to the technical field of energetic material passivation. The method uses typical high-energy-density nitramine oxidants HMX and CL-20 as passivation modification objects, adopts nano-sized and surface-functionalized passivated energetic crystals as passivation agents, and constructs functional groups based on strong intermolecular interactions between crystal surfaces, using crystal assembly as a driving force to obtain co-granular crystals with a dense structure. This method can not only maintain the high energy density of the nitramine oxidant, but also effectively improve its safety.

[0024] The present invention proposes a modified co-granular nitramine crystal based on interface enhancement passivation and a preparation method thereof, which can uniformly assemble high-energy oxidants and passivated energetic materials in any proportion, effectively solving the problem of low energy density of traditional passivated energetic eutectics prepared at a specific molar ratio. On the other hand, the strong interaction between the two energetic crystals can form a tight interface along a specific crystal direction, and the dense and non-porous structure is conducive to taking into account both the energy performance and safety performance of the high-energy oxidant, thereby solving the problem of "passivity and high energy" being difficult to achieve at the same time.

[0025] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: the process is simple, the cost of raw materials is low, and the product morphology is uniform and reproducible; compared with the particles obtained by the hydrothermal method and the solvent-non-solvent method, the particles have higher density and uniformity, and are tightly combined through the interface, thus showing excellent thermal stability and safety performance; the reaction activity and energy release rate of the insensitive nitramine co-particles are adjustable and controllable based on the precise control of the component particle grading, the type of interface material and the thickness; through refined design and process optimization, the sensitivity of the co-particles is greatly reduced while ensuring that the proportion of insensitive components in the co-particles is extremely low. The present invention provides a new technical approach for the high-energy insensitivity modification of energetic materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Flow chart of the preparation of co-particles prepared according to Examples 1-13 of the present invention

[0027] Figure 2 The scanning electron microscope images of the co-particles prepared according to Examples 1-13 of the present invention are shown in FIG.

[0028] Figure 3 The X-ray powder diffraction pattern of the co-particles prepared according to Example 3 of the present invention is

[0029] Figure 4 The DSC analysis diagram of the co-particles prepared according to Examples 3, 10 and 11 of the present invention is shown in FIG.

[0030] Figure 5 The scanning electron microscope images of the co-particles prepared according to Examples 3, 12 and 13 of the present invention are shown in FIG. DETAILED DESCRIPTION

[0031] The present invention will now be further described with reference to the embodiments and the accompanying drawings:

[0032] A method for preparing co-granular nitramine crystals based on interface enhancement passivation modification, characterized in that the steps are as follows:

[0033] Step 1: Place the weighed insensitive energetic crystals in a zirconia ball mill, add 0.3 mm zirconia ball mill beads at a ball-to-material ratio of 20:1, prepare a dispersion liquid at a volume ratio of anhydrous ethanol and water of 1:1, and add the dispersion liquid to the ball mill at a material-to-liquid ratio of 1:10, set the speed to 350 r / min, and obtain nano-insensitive energetic crystals after ball milling for 6 hours;

[0034] Step 2: prepare a buffer solution with a pH of 8.5 to 9.0, disperse the nano-insensitive energetic crystals obtained in step 1 in the buffer solution, add dopamine hydrochloride, continue stirring for 2 hours, filter, wash, and dry to obtain the surface-functionalized nano-insensitive energetic crystals;

[0035] Step 3: dissolving the nitramine oxidant in an organic solvent at a certain temperature to obtain a nitramine oxidant solution;

[0036] Step 4: dispersing the surface-functionalized nano-insensitive energetic crystals obtained in step 2 in the solution obtained in step 3 to obtain a precursor suspension;

[0037] Step 5: Set the inlet temperature, feed rate and other parameters, spray-dry the dispersed suspension obtained in step 4 to obtain "nitramine oxidant / interface layer / insensitive nanocrystals" co-particles.

[0038] In step 3, the nitramine oxidant is one of CL-20 or HMX, the organic solvent is one of ethyl acetate or dimethyl sulfoxide, the concentration of the nitramine oxidant solution is 0.15-0.5 g / ml, and the temperature is 30-50° C.;

[0039] In the step 4, the mass ratio of the surface functionalized nano-insensitive energetic crystals to the nitramine oxidant is 1:9, 1:95 or 1:99;

[0040] The inlet temperature of the spray drying in step 5 is 60-180° C., and the feed rate is 3-6 ml / min.

[0041] Example 1

[0042] A co-granular nitramine crystal modified by interface enhancement passivation and a preparation method thereof, comprising the following process steps:

[0043] Nano-crystallization of insensitive energetic crystals: Weigh 10 g of TATB in a zirconia ball mill, add 200 g of zirconia ball mill beads (0.3 mm) at a ball-to-material ratio of 20:1, prepare 100 ml of dispersion liquid at a volume ratio of anhydrous ethanol and water of 1:1, add it to the ball mill, set the speed to 350 r / min, and mill for 6 h to obtain nano-TATB;

[0044] Surface wettability treatment of nano-insensitive energetic crystals: prepare a buffer solution with a pH of 8.5-9.0, weigh 3 g of nano-TATB and divide it into the buffer solution, ultrasonically disperse it for 30 min, add dopamine hydrochloride, continue stirring for 2 h, filter, wash and dry to obtain TATB@PDA;

[0045] Preparation of precursor suspension: Weigh 1.8 g of CL-20 and dissolve it in 4 ml of ethyl acetate at 50°C to obtain a CL-20 solution with a concentration of 0.45 g / ml. Weigh 0.2 g of TATB@PDA and disperse it in the CL-20 solution. Ultrasonic oscillation is performed for 30 min to obtain a precursor suspension.

[0046] Preparation of co-particles: The precursor suspension was kept at 50°C, and the inlet temperature was set to 80°C. The precursor suspension entered the spray dryer at a rate of 4.5 ml / min through a peristaltic pump to obtain CL-20-TATB@PDA co-particles.

[0047] The CL-20-TATB@PDA co-particles prepared in Example 1 were analyzed by scanning electron microscopy (SEM). The crystal morphology is shown in Figure 2 As shown. Figure 2 It can be seen that the sample prepared in Example 1 is a spherical particle with some defects on the surface.

[0048] Example 2

[0049] A co-granular nitramine crystal modified by interface enhancement passivation and a preparation method thereof, comprising the following process steps:

[0050] Nano-crystallization of insensitive energetic crystals: Weigh 10 g of TATB in a zirconia ball mill, add 200 g of zirconia ball mill beads (0.3 mm) at a ball-to-material ratio of 20:1, prepare 100 ml of dispersion liquid at a volume ratio of anhydrous ethanol and water of 1:1, add it to the ball mill, set the speed to 350 r / min, and mill for 6 h to obtain nano-TATB;

[0051] Surface wettability treatment of nano-insensitive energetic crystals: prepare a buffer solution with a pH of 8.5-9.0, weigh 3 g of nano-TATB and disperse it in the buffer solution, ultrasonically disperse it for 30 min, add dopamine hydrochloride, continue stirring for 2 h, filter, wash, and dry to obtain TATB@PDA;

[0052] Preparation of precursor suspension: Weigh 1.8 g of CL-20 and dissolve it in 12 ml of ethyl acetate at 50°C to obtain a CL-20 solution with a concentration of 0.15 g / ml. Weigh 0.2 g of TATB@PDA and disperse it in the CL-20 solution. Ultrasonic oscillation is performed for 30 min to obtain a precursor suspension.

[0053] Preparation of co-particles: The precursor suspension was kept at 50°C, and the inlet temperature was set to 80°C. The precursor suspension entered the spray dryer at a rate of 4.5 ml / min through a peristaltic pump to obtain CL-20-TATB@PDA co-particles.

[0054] The CL-20-TATB@PDA co-particles prepared in Example 2 were analyzed by scanning electron microscopy (SEM). The crystal morphology is shown in Figure 2 As shown. Figure 2 It can be seen that the sample prepared in Example 2 is spherical particles with no surface defects.

[0055] Example 3

[0056] A co-granular nitramine crystal modified by interface enhancement passivation and a preparation method thereof, comprising the following process steps:

[0057] Nano-crystallization of insensitive energetic crystals: Weigh 10 g of TATB in a zirconia ball mill, add 200 g of zirconia ball mill beads (0.3 mm) at a ball-to-material ratio of 20:1, prepare 100 ml of dispersion liquid at a volume ratio of anhydrous ethanol and water of 1:1, add it to the ball mill, set the speed to 350 r / min, and mill for 6 h to obtain nano-TATB;

[0058] Surface wettability treatment of nano-insensitive energetic crystals: prepare a buffer solution with a pH of 8.5-9.0, weigh 3 g of nano-TATB and disperse it in the buffer solution, ultrasonically disperse it for 30 min, add dopamine hydrochloride, continue stirring for 2 h, filter, wash, and dry to obtain TATB@PDA;

[0059] Preparation of precursor suspension: Weigh 1.8 g of CL-20 and dissolve it in 12 ml of ethyl acetate at 50°C to obtain a CL-20 solution with a concentration of 0.15 g / ml. Weigh 0.2 g of TATB@PDA and disperse it in the CL-20 solution. Ultrasonic oscillation is performed for 30 min to obtain a precursor suspension.

[0060] Preparation of co-particles: The precursor suspension was kept at 50°C, and the inlet temperature was set to 60°C. The precursor suspension entered the spray dryer at a rate of 4.5 ml / min through a peristaltic pump to obtain CL-20-TATB@PDA co-particles.

[0061] The CL-20-TATB@PDA co-particles prepared in Example 3 were analyzed by scanning electron microscopy (SEM). The crystal morphology is shown in Figure 2 As shown. Figure 2 It can be seen that the sample prepared in Example 3 is spherical particles with uniform size distribution and no defects.

[0062] The CL-20-TATB@PDA co-particles prepared in Example 3 were subjected to XRD analysis. Example 3 had strong diffraction peaks at 13.76°, 24.21° and 28.42°, which were different from the diffraction peak positions of the raw materials CL-20 and TATB@PDA. The co-particles formed a new crystal structure.

[0063] The CL-20-TATB@PDA co-particles prepared in Example 3 were subjected to DSC analysis. The analysis results showed that the crystal had good thermal stability, with an exothermic peak at 233.2°C, and no endothermic peak of crystal transformation, indicating that the crystal stability was improved.

[0064] Example 4

[0065] A co-granular nitramine crystal modified by interface enhancement passivation and a preparation method thereof, comprising the following process steps:

[0066] Nano-crystallization of insensitive energetic crystals: Weigh 10 g of TATB in a zirconia ball mill, add 200 g of zirconia ball mill beads (0.3 mm) at a ball-to-material ratio of 20:1, prepare 100 ml of dispersion liquid at a volume ratio of anhydrous ethanol and water of 1:1, add it to the ball mill, set the speed to 350 r / min, and mill for 6 h to obtain nano-TATB;

[0067] Surface wettability treatment of nano-insensitive energetic crystals: prepare a buffer solution with a pH of 8.5-9.0, weigh 3 g of nano-TATB and disperse it in the buffer solution, ultrasonically disperse it for 30 min, add dopamine hydrochloride, continue stirring for 2 h, filter, wash, and dry to obtain TATB@PDA;

[0068] Preparation of precursor suspension: Weigh 1.8 g of CL-20 and dissolve it in 12 ml of ethyl acetate at 50°C to obtain a CL-20 solution with a concentration of 0.15 g / ml. Weigh 0.2 g of TATB@PDA and disperse it in the CL-20 solution. Ultrasonic oscillation is performed for 30 min to obtain a precursor suspension.

[0069] Preparation of co-particles: The precursor suspension was kept at 50°C, the inlet temperature was set to 70°C, and the precursor suspension entered the spray dryer at a rate of 4.5 ml / min through a peristaltic pump to obtain CL-20-TATB@PDA co-particles.

[0070] The CL-20-TATB@PDA co-particles prepared in Example 4 were analyzed by scanning electron microscopy (SEM). The crystal morphology thereof is shown in FIG. Figure 2 As shown. Figure 2 It can be seen that the sample prepared in Example 4 is spherical particles, and it can be seen from the broken particles that TATB@PDA crystal particles exist inside.

[0071] Example 5

[0072] A co-granular nitramine crystal modified by interface enhancement passivation and a preparation method thereof, comprising the following process steps:

[0073] Nano-crystallization of insensitive energetic crystals: Weigh 10 g of TATB in a zirconia ball mill, add 200 g of zirconia ball mill beads (0.3 mm) at a ball-to-material ratio of 20:1, prepare 100 ml of dispersion liquid at a volume ratio of anhydrous ethanol and water of 1:1, add it to the ball mill, set the speed to 350 r / min, and mill for 6 h to obtain nano-TATB;

[0074] Surface wettability treatment of nano-insensitive energetic crystals: prepare a buffer solution with a pH of 8.5-9.0, weigh 3 g of nano-TATB and disperse it in the buffer solution, ultrasonically disperse it for 30 min, add dopamine hydrochloride, continue stirring for 2 h, filter, wash, and dry to obtain TATB@PDA;

[0075] Preparation of precursor suspension: Weigh 1.8 g of CL-20 and dissolve it in 12 ml of ethyl acetate at 50°C to obtain a CL-20 solution with a concentration of 0.15 g / ml. Weigh 0.2 g of TATB@PDA and disperse it in the CL-20 solution. Ultrasonic oscillation is performed for 30 min to obtain a precursor suspension.

[0076] Preparation of co-particles: The precursor suspension was kept at 50°C, the inlet temperature was set to 80°C, and the precursor suspension entered the spray dryer at a rate of 6 ml / min through a peristaltic pump to obtain CL-20-TATB@PDA co-particles.

[0077] The CL-20-TATB@PDA co-particles prepared in Example 5 were subjected to scanning electron microscopy (SEM) analysis, and the crystal morphology thereof was as follows: Figure 2 As shown. Figure 2 It can be seen that the sample prepared in Example 5 is spherical particles, and some particles are broken.

[0078] Example 6

[0079] A co-granular nitramine crystal modified by interface enhancement passivation and a preparation method thereof, comprising the following process steps:

[0080] Nano-crystallization of insensitive energetic crystals: Weigh 10 g of TATB in a zirconia ball mill, add 200 g of zirconia ball mill beads (0.3 mm) at a ball-to-material ratio of 20:1, prepare 100 ml of dispersion liquid at a volume ratio of anhydrous ethanol and water of 1:1, add it to the ball mill, set the speed to 350 r / min, and mill for 6 h to obtain nano-TATB;

[0081] Surface wettability treatment of nano-insensitive energetic crystals: prepare a buffer solution with a pH of 8.5-9.0, weigh 3 g of nano-TATB and disperse it in the buffer solution, ultrasonically disperse it for 30 min, add dopamine hydrochloride, continue stirring for 2 h, filter, wash, and dry to obtain TATB@PDA;

[0082] Preparation of precursor suspension: Weigh 1.8 g of CL-20 and dissolve it in 12 ml of ethyl acetate at 50°C to obtain a CL-20 solution with a concentration of 0.15 g / ml. Weigh 0.2 g of TATB@PDA and disperse it in the CL-20 solution. Ultrasonic oscillation is performed for 30 min to obtain a precursor suspension.

[0083] Preparation of co-particles: The precursor suspension was kept at 50°C, the inlet temperature was set at 60°C, and the precursor suspension entered the spray dryer at a rate of 3 ml / min through a peristaltic pump to obtain CL-20-TATB@PDA co-particles.

[0084] The CL-20-TATB@PDA co-particles prepared in Example 6 were subjected to scanning electron microscopy (SEM) analysis, and the crystal morphology thereof was as follows: Figure 2 As shown. Figure 2 It can be seen that the sample prepared in Example 6 is spherical particles, and the surface density of the spherical particles is poor.

[0085] Example 7

[0086] A co-granular nitramine crystal modified by interface enhancement passivation and a preparation method thereof, comprising the following process steps:

[0087] Nano-crystallization of insensitive energetic crystals: Weigh 10 g of TATB in a zirconia ball mill, add 200 g of zirconia ball mill beads (0.3 mm) at a ball-to-material ratio of 20:1, prepare 100 ml of dispersion liquid at a volume ratio of anhydrous ethanol and water of 1:1, add it to the ball mill, set the speed to 350 r / min, and mill for 6 h to obtain nano-TATB;

[0088] Surface wettability treatment of nano-insensitive energetic crystals: prepare a buffer solution with a pH of 8.5-9.0, weigh 3 g of nano-TATB and disperse it in the buffer solution, ultrasonically disperse it for 30 min, add dopamine hydrochloride, continue stirring for 2 h, filter, wash, and dry to obtain TATB@PDA;

[0089] Preparation of precursor suspension: Weigh 1.9 g of CL-20 and dissolve it in 12 ml of ethyl acetate at 50°C to obtain a CL-20 solution with a concentration of 0.15 g / ml. Weigh 0.1 g of TATB@PDA and disperse it in the CL-20 solution. Ultrasonic oscillation is performed for 30 min to obtain a precursor suspension.

[0090] Preparation of co-particles: The precursor suspension was kept at 50°C, and the inlet temperature was set to 60°C. The precursor suspension entered the spray dryer at a rate of 4.5 ml / min through a peristaltic pump to obtain CL-20-TATB@PDA co-particles.

[0091] The CL-20-TATB@PDA co-particles prepared in Example 7 were analyzed by scanning electron microscopy (SEM). The crystal morphology thereof is as follows: Figure 2 As shown. Figure 2 It can be seen that the sample prepared in Example 7 is spherical particles with uniform size distribution and no defects.

[0092] The CL-20-TATB@PDA co-particles prepared in Example 7 were subjected to XRD analysis. Example 3 had strong diffraction peaks at 13.76°, 24.21° and 28.42°, which were different from the diffraction peak positions of the raw materials CL-20 and TATB@PDA. The co-particles formed a new crystal structure.

[0093] The CL-20-TATB@PDA co-particles prepared in Example 7 were subjected to DSC analysis. The analysis results showed that the crystal had good thermal stability, with an exothermic peak at 233.2°C, and no endothermic peak of crystal transformation, indicating that the crystal stability was improved.

[0094] Example 8

[0095] In order to reflect the advantages of a co-granular nitramine crystal based on interface enhancement passivation and its preparation method, Example 8 was prepared by hydrothermal method;

[0096] Preparation of co-particles by hydrothermal method: CL-20 and TATB were uniformly dispersed in deionized water by ultrasound, and then placed in a hydrothermal reactor, and the temperature of the program-controlled thermostat was set, and the reaction was carried out at 120° C. for 24 hours, and then washed and dried to obtain Example 8;

[0097] The crystal morphology of Example 8 was analyzed by scanning electron microscope (SEM). Figure 2 As shown. Figure 2 It can be seen that the sample prepared in Example 8 is a large spindle-shaped particle, with some TATB particles distributed on the surface and a small part of TATB particles embedded inside. The particle size is relatively large, the uniformity of TATB is poor, and the density needs to be improved.

[0098] Example 9

[0099] In order to reflect the advantages of a co-granular nitramine crystal based on interface enhancement passivation and its preparation method, Example 9 was prepared by a solvent-nonsolvent method;

[0100] Preparation of co-particles by the solvent-non-solvent method: CL-20 was completely dissolved in the solvent ethyl acetate, and the non-solvent n-heptane dispersed with insensitive energetic nanocrystals was added to the above solution at a certain rate of 4.5 ml / min through a peristaltic pump to make it uniformly mixed and crystallized. After multiple washing and drying, Example 9 was obtained.

[0101] The crystal morphology of Example 9 was analyzed by scanning electron microscope (SEM). Figure 2 As shown. Figure 2 It can be seen that the sample prepared in Example 9 is an agglomerate of TATB and CL-20, which has poor density and uniformity and cannot form co-particles.

[0102] Example 10

[0103] In order to reflect the advantages of a co-granular nitramine crystal based on interface enhancement passivation and its preparation method, a mechanical mixture example 10 was prepared by grinding method;

[0104] Preparation of co-particles by grinding method: CL-20 and TATB were placed in a mortar at the same time, and a small amount of anhydrous ethanol as an auxiliary flux was added. After sufficient grinding, a CL-20 / TATB mechanical mixture was obtained, namely Example 10.

[0105] The crystal morphology of Example 10 was analyzed by scanning electron microscope (SEM). Figure 2 As shown. Figure 2 It can be seen that the sample prepared in Example 10 is a spindle, with a large number of TATB particles attached to the surface of the CL-20 crystal, and no TATB inside, which means it is a mechanical mixture of the two.

[0106] Example 11

[0107] In order to reflect the advantages of the interface of the modified co-particle nitramine crystal based on interface enhancement passivation and the preparation method thereof, unfunctionalized TATB and CL-20 were used to prepare co-particles to obtain Example 11:

[0108] Nano-crystallization of insensitive energetic crystals: Weigh 10 g of TATB in a zirconia ball mill, add 200 g of zirconia ball mill beads (0.3 mm) at a ball-to-material ratio of 20:1, prepare 100 ml of dispersion liquid at a volume ratio of anhydrous ethanol and water of 1:1, add it to the ball mill, set the speed to 350 r / min, and mill for 6 h to obtain nano-TATB;

[0109] Preparation of precursor suspension: Weigh 1.8 g of CL-20 and dissolve it in 12 ml of ethyl acetate at 50° C. to obtain a CL-20 solution with a concentration of 0.15 g / ml. Weigh 0.2 g of TATB and disperse it in the CL-20 solution. Ultrasonic oscillation is performed for 30 minutes to obtain a precursor suspension.

[0110] Preparation of co-particles: The precursor suspension was kept at 50°C, and the inlet temperature was set to 60°C. The precursor suspension entered the spray dryer at a rate of 4.5 ml / min through a peristaltic pump to obtain CL-20-TATB co-particles.

[0111] The CL-20-TATB co-particles prepared in Example 11 were analyzed by scanning electron microscopy (SEM). The crystal morphology thereof is as follows: Figure 2 As shown. Figure 2 It can be seen that the sample prepared in Example 3 is spherical particles, some of which are broken and the density needs to be improved.

[0112] The CL-20-TATB co-particles prepared in Example 11 were subjected to DSC analysis. Figure 4 It shows that the crystal has good thermal stability, with an exothermic peak at 230.2℃ and a crystal transformation endothermic peak at 144.6℃, and poor thermal stability.

[0113] Example 12, Example 13

[0114] In order to study the effect of the content of the insensitive component TATB on the co-particle structure, based on the process conditions of Example 3, only the addition amount of TATB was changed to 1% and 5%, and finally Examples 12 and 13 were obtained;

[0115] The CL-20-TATB@PDA co-particles prepared in Examples 3, 12, and 13 were analyzed by scanning electron microscopy (SEM). The crystal morphology thereof is shown in FIG. Figure 5 As shown. Figure 2It can be seen that the sample prepared in Example 12 is a dense spherical particle. When the amount of TATB added gradually increases, Example 13 and Example 3 gradually change into a "litchi-like" structure, in which many crystals are tightly combined to form a spherical particle.

[0116] The CL-20-TATB@PDA co-particles prepared in Examples 3, 12, and 13 were subjected to impact sensitivity analysis, and the results are shown in Table 1. The energy required for impact detonation of the CL-20-TATB@PDA co-particles is greater than that of pure CL-20, and the sensitivity is significantly improved.

[0117] Table 1 Impact sensitivity results of co-particles prepared according to Examples 3, 12 and 13 of the present invention

[0118] sample Impact sensitivity (J) CL-20 10 Example 12 14 Example 13 ＞14 Example 3 ＞14

Claims

1. A method for preparing co-granular nitramine crystals based on interface enhancement passivation modification, characterized in that Here are the steps: Step 1: nano-processing the insensitive energetic crystals by wet ball milling to obtain insensitive energetic nanocrystals; Step 2: coating the surface of the insensitive energetic nanocrystals with a layer of polydopamine by in-situ self-polymerization to obtain surface functionalized insensitive energetic nanocrystals; Step 3: adding the surface functionalized insensitive energetic crystals into a precursor solution, and performing ultrasonic dispersion to obtain a dispersed suspension; the precursor solution is obtained by dissolving a nitramine oxidant in an organic solvent; Step 4: spray drying the dispersed suspension to obtain "nitramine oxidant / interface layer / insensitive energetic nanocrystal" co-particles; the content of the nitramine oxidant is 90% to 99%, and the content of the surface functionalized insensitive energetic crystals is 1% to 10%; The particle size of the insensitive energetic crystals after nano-crystallization in step 1 is 200-500 nm; The coating time in step 2 is 2 hours, and the thickness of the coated polydopamine is 3-5 nm; The nitramine oxidant is octochrome HMX or hexanitrohexaazaisowurtzitane CL-20; The insensitive energetic crystal is triaminotrinitrobenzene TATB, 1-oxy-2,6-diamino-3,5-dinitropyrazine LLM-105 or 1,1-diamino-2,2-dinitroethylene FOX-7.

2. The method for preparing the interfacial enhanced passivation modified co-granular nitramine crystals according to claim 1, characterized in that: The ultrasonic dispersion time in step 3 is 30 min.

3. The method for preparing the interfacial enhanced passivation modified co-granular nitramine crystals according to claim 1, characterized in that: The organic solvent in step 3 is dimethyl sulfoxide or ethyl acetate.

4. The method for preparing the interfacial enhanced passivation modified co-granular nitramine crystals according to claim 1, characterized in that: The temperature of the precursor solution is 30-50°C, and the concentration of the nitramine oxidant in the precursor solution is 0.15-0.5 g / ml.

5. The method for preparing the interfacial enhanced passivation modified co-granular nitramine crystals according to claim 1, characterized in that: The inlet temperature of the spray drying in step 4 is 60-180°C, and the feed rate is 3-6 ml / min.

6. An interface enhanced passivation modified co-granular nitramine crystal obtained by the preparation method according to any one of claims 1 to 5, characterized in that Calculated by mass percentage, the composition includes: 90% to 99% of nitramine oxidant and 1% to 10% of surface functionalized insensitive energetic crystals.

7. The interface enhanced passivation modified co-granular nitramine crystal according to claim 6, characterized in that: The nitramine oxidant is octogen HMX or hexanitrohexaazaisowurtzitane CL-20.

8. The interface enhanced passivation modified co-granular nitramine crystal according to claim 6, characterized in that: The insensitive energetic crystal is triaminotrinitrobenzene TATB, 1-oxy-2,6-diamino-3,5-dinitropyrazine LLM-105 or 1,1-diamino-2,2-dinitroethylene FOX-7.

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