High-activity energetic microsphere containing nano boron powder and ETN and preparation method of high-activity energetic microsphere

Abstract

The invention discloses a high-activity energetic microsphere containing nano boron powder and ETN and a preparation method of the high-activity energetic microsphere, and belongs to the field of explosives. The microspheres are formed by uniformly mixing nano boron powder, ETN and NC, NC serves as an adhesive to enable the mixture to be in a microsphere shape, and ETN serves as a plasticizer of NC to improve the physical performance and energy release efficiency of the microspheres. Wherein ETN serving as a plasticizer of NC and NC can be decomposed and release high-temperature oxygen before nB is ignited, and nB is preheated and activated, so that the ignition temperature of nB is lower than 500 DEG C, and the combustion rate of nB is 1000 times that of micron boron. The preparation method of the high-activity energetic microspheres containing nano boron powder and ETN comprises the following steps: chemically modifying by using a silane coupling agent, combining PEG and nB, forming by using a microfluidic O / W emulsion method, and controlling parameters such as pH and flow velocity to prepare the microspheres with high sphericity and uniform dispersion.

Description

Technical Field

[0001] The invention belongs to the field of explosives and in particular relates to a high-activity energetic microsphere containing nano-boron powder and ETN and a preparation method thereof. Background Art

[0002] Nanoboron powder (nB) is a novel and highly interesting material for advanced energetic materials. For ramjet engines, boron's heat of combustion (-58.9 kJ / g) is significantly higher than that of aluminum (-31.0 kJ / g), magnesium (-24.8 kJ / g), lithium (-42.7 kJ / g), and silicon (-32.4 kJ / g), and only lower than that of hydrogen (-142.8 kJ / g) and beryllium (-67.7 kJ / g). Therefore, ramjet propellants incorporating boron powder possess extremely high energy performance. However, micronized boron powder (μB) has several significant drawbacks. For example, the boiling point of its oxide layer is as high as 1860°C, while the melting and boiling points of the elemental boron particles beneath the oxide layer are approximately 2300°C and 3658°C, respectively. Consequently, μB particles cannot achieve gaseous combustion, as with metallic magnesium particles, nor liquid combustion, as with metallic aluminum particles. μB particles remain solid during combustion, reducing their burning rate and efficiency. For ramjets, the measured heat of combustion of μB-containing propellants is far lower than the theoretical value due to the difficulty of ignition and incomplete combustion of μB.

[0003] From a thermodynamic and kinetic perspective, nB is an ideal fuel for ramjets, but its practical engineering application still faces several significant challenges. First, preparing boron powder with a particle size of less than 80 nanometers is extremely difficult, and chemical cracking methods are the only viable method. Boron nanoparticles with a particle size of less than 80 nm can be obtained through controlled reduction of gaseous boron compounds. However, the surface of nB particles is typically covered with a waxy film (a mixture of B₂O₃ and boric acid), which makes the physical state of the nB surface similar to that of paraffin wax. Furthermore, due to its specific surface area exceeding 200 m₂ / g, it is difficult to uniformly mix large amounts of nB powder with the other propellant components during the kneading process. Therefore, by adding a small amount of binder, nB can be prepared into boron microspheres with a size of 30-200 μm. This would solve the problem of the inability of nB powder to be evenly dispersed in the propellant slurry without affecting the kinetic and thermodynamic properties of the combustion process. We have found that microfluidic preparation is a very suitable technical means to achieve this goal.

[0004] In recent years, microfluidics has been widely used in the field of materials science. Compared with other traditional methods, using microfluidics to prepare highly spherical droplets offers advantages such as miniaturized equipment, low reagent consumption, high precision, ease of use, and flexibility. Using droplet microfluidics, immiscible dispersed and continuous phases are brought together in microchannels. Under the influence of shear forces and surface tension, highly dispersed microdroplets are formed. After the solvent in the microdroplets diffuses out, the nB particles are encapsulated in a "binder," forming a microcapsule structure. This solves the problem of difficult dispersion of nB powder. During combustion, the fluororubber releases high-temperature fluorine-containing gases, causing the nB particles to burn rapidly. This not only improves the combustion efficiency of the nB but also further reduces the ignition temperature of the nB particles.

[0005] The present invention aims to add a small amount of high-energy binder nitrocellulose (NC, nitrogen content 12.5 wt.%) to nB powder and use microfluidics technology to prepare micron-sized nB microspheres to solve the problem of difficult dispersion of nB powder. From the perspective of combustion performance, relying solely on NC to support combustion is insufficient for microspheres. Therefore, an innovation of the present invention is that the positive oxygen balance and high-energy nitrate-based high-energy explosive 1,2,3,4-butanetetrol tetranitrate (ETN, C4H5N4O) are introduced into the nB microspheres. 12 ) acts as a plasticizer for NC, improving the physical and mechanical properties of the nB microspheres and accelerating their energy release. In a ramjet, the binder NC and high explosive ETN surrounding the nB particles rapidly and fully decompose and burn before the nB ignites, releasing extremely hot oxygen or other oxidizing gases that "preheat" and "preactivate" the nanoboron particles. This significantly improves the ignition and combustion performance of the nB in the ramjet. This invention provides a powerful reference for the future application of nB powder in hypersonic ramjets. Summary of the Invention

[0006] In order to solve the problem that nB powder is difficult to disperse, the present invention provides the following technical solutions:

[0007] A highly active energetic microsphere containing nano-boron powder and ETN, comprising the following parts by weight:

[0008] 0.5-1g γ-aminopropyltriethoxysilane (KH-550), 0.1-0.2g octadecylamine, 0.1-0.2g Tween-80, 1-2g nB, 0.2-0.3g high-energy adhesive nitrocellulose (NC), 0.2-0.3g 1,2,3,4-butanetetrol tetranitrate (ETN), 0.05-0.1g diphenylamine (DPA), 0.05-0.1g KH-570, 0.15-0.2g ammonium perchlorate (AP), 0.02-0.1g 5-nitrotetrazolyl lead (Pb(NTA)2), 0.01-0.05g 2,4-dinitrophenol (DNP), 0.03-0.1g polyethylene glycol 400 (PEG-400).

[0009] Preferably, the microspheres are formed by uniformly mixing nano boron powder, ETN and NC.

[0010] Preferably, the introduced ETN acts as a plasticizer of NC, improves the physical and mechanical properties of nB microspheres, and accelerates the energy release of nB microspheres.

[0011] Preferably, the binder NC and the secondary explosive ETN of the nB particles decompose and burn before the nB is ignited, releasing extremely high temperature oxygen to preheat and preactivate the nano-boron particles, thereby significantly improving the ignition and combustion performance of the nB.

[0012] Preferably, the ignition temperature of the nano-boron (nB) is 500° C., which is lower than the ignition temperature of micro-boron (μB) of 2400° C., and the combustion rate of nB is 1000 times that of μB, which can release a large amount of heat energy in a very short time.

[0013] Preferably, the DPA in the system inhibits the decomposition of NC in a high temperature environment, reduces the release of gas, and improves the chemical compatibility of nB and NC.

[0014] A method for preparing high-activity energetic microspheres containing nano-boron powder and ETN comprises the following steps:

[0015] S1: 0.5 g KH-550, 0.1 g octadecylamine, 0.1 g Tween-80, 0.05 g KH-570, and 0.03 g PEG-400 were added to 10 mL of a 3:1 volume ratio ethanol and water mixture. The mixture was stirred magnetically in a 40°C water bath for 30 minutes to promote hydrolysis, and then allowed to stand for 1 hour to allow complete hydrolysis.

[0016] S2: The pH of the mixed solution of S1 was adjusted with a 10% NaOH aqueous solution, and then allowed to stand at room temperature;

[0017] S3: Then add 1g nB into 10mL anhydrous ethanol, drop into the mixed solution in S2, stir, filter, and dry to obtain modified nano-boron powder;

[0018] S4: 0.2 g NC, 0.2 g ETN, 0.15 g AP, and 0.02 g Pb(NTA)2 were dissolved in 20 mL of ethyl acetate mixed solvent, and 0.05 g diphenylamine (DPA) and 0.01 g 2,4-dinitrophenol (DNP) were added as a two-component stabilizer. The mixture was dissolved by ultrasonication in a water bath at 60 °C.

[0019] S5: Under the synergistic action of ultrasound and mechanical stirring, 0.6 g of surface-modified nB powder was added to the above solution three times to form a dispersed phase with a solid content of 15%. The continuous phase was then a 2% aqueous solution of sodium dodecylbenzenesulfonate, and the receiving phase was a deionized water solution containing 0.1% tris(hydroxymethyl)aminomethane;

[0020] S6: Under the control of the syringe pump, the continuous phase and the dispersed phase interact with each other, and the dispersed phase solution is sheared to form oil / water (0 / W) droplets;

[0021] S7: After the droplets enter the receiving phase, stirring is performed to accelerate the diffusion of the solvent. The solidified microspheres are washed three times with deionized water and then dried in a vacuum drying oven at 40°C to obtain nB / NC / ETN microspheres.

[0022] Preferably, the pH in S2 is adjusted to be between 9 and 10 and ultrasonically dispersed at 200 KHz for 30 minutes, and finally allowed to stand at room temperature for 6 hours.

[0023] Preferably, the magnetic stirring in S3 is carried out at 300 r / min for 12 hours, followed by drying at 50°C.

[0024] Preferably, the continuous phase in S6 needs to be controlled at 3.5 mL min -1 , the dispersed phase was heated at 0.05 mL min -1 flow rate interactions.

[0025] The technical effects and advantages of the high-activity energetic microspheres containing nano-boron powder and ETN of the present invention are as follows:

[0026] 1. The nB / NC / ETN microspheres prepared in this patent have a very high sphericity, are uniform in size, have no adhesion or agglomeration between the spheres, and all the surfaces of the spheres are very smooth.

[0027] 2. This patent states that the nB / NC / ETN microspheres prepared by the present invention have very strong combustion performance and high activity.

[0028] 3. This patent states that the nB / NC / ETN microspheres prepared by the present invention have good vacuum stability.

[0029] 4. This patent states that the nB particles modified with the composite surfactant KH-550, octadecylamine and Tween-80 used in the present invention have high dispersibility and suspension in ethyl acetate and hardly settle even after being placed for 3 months. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The following are SEM photos of nB powder used in Example 1, Comparative Example 1 and Comparative Example 2 of the present invention;

[0031] Figure 2 This is a SEM image of the nB / NC / ETN microspheres prepared in Example 1 of the present invention;

[0032] Figure 3 This is the EDS spectrum of the nB / NC / ETN microspheres prepared in Example 1 of the present invention;

[0033] Figure 4 XRD pattern of nB / NC / ETN microspheres prepared in Example 1 of the present invention;

[0034] Figure 5 This is the XPS spectrum of the nB / NC / ETN microspheres prepared in Example 1 of the present invention;

[0035] Figure 6 This is a photo of the strongest burning flame of the nB / NC / ETN microspheres prepared in Example 1 of the present invention;

[0036] Figure 7 This is a photo of the strongest flame of the nB / NC microspheres prepared in Comparative Example 1 of the present invention;

[0037] Figure 8 This is a photo of the strongest flame of the nB / F2602 microspheres prepared in Comparative Example 2 of the present invention;

[0038] Figure 9 The pressure-time curves of the combustion process of Example 1, Comparative Example 1 and Comparative Example 2 of the present invention;

[0039] Figure 10 The temperature-time curves of the combustion process of Example 1, Comparative Example 1 and Comparative Example 2 of the present invention;

[0040] Figure 11 These are photos of the surface-modified nB in the examples and comparative examples of the present invention after being suspended in ethyl acetate for 3 months. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0042] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus. In the absence of further restrictions, the elements defined by the sentence "include..." do not exclude the presence of other identical elements in the process, method, article or apparatus that includes the elements.

[0043] refer to Figure 1-11 Example 1 details a high-activity energetic microsphere containing nano-boron powder and ETN and its preparation method

[0044] Example 1

[0045] This embodiment provides a method for preparing highly active energetic microspheres containing nano-boron powder and ETN, and the following implementation contents include:

[0046] Purpose of the experiment:

[0047] Preparation of high-activity energetic microspheres containing nano-boron powder and ETN.

[0048] Experimental materials:

[0049] KH-550, octadecylamine, Tween-80, 10% NaOH aqueous solution, nB, NC, ETN, diphenylamine (DPA), ethyl acetate, the continuous phase and receiving phase are 2% by mass sodium dodecylbenzenesulfonate in deionized water, KH-570, ammonium perchlorate (AP), 5-nitrotetrazoline lead (Pb(NTA)2)

[0050] Experimental steps:

[0051] S1: 0.5 g KH-550, 0.1 g octadecylamine, 0.1 g Tween-80, 0.05 g KH-570, and 0.03 g PEG-400 were added to a mixture of 10 mL of ethanol and water. The mixture was stirred magnetically in a 40°C water bath for 30 minutes to promote hydrolysis, and then allowed to stand for 1 hour to allow complete hydrolysis.

[0052] S2: The pH value of the mixed solution of S1 was adjusted to 9 with 10% NaOH aqueous solution, ultrasonicated for 30 minutes, and then allowed to stand at room temperature for 6 hours;

[0053] S3: Then, 1 g of nB was added to 10 mL of anhydrous ethanol, and the mixed solution in S2 was added dropwise. The mixture was magnetically stirred at a speed of 300 r / min for 12 hours, and then filtered and dried in a 50°C water bath to obtain modified nano-boron powder.

[0054] S4: 0.2 g NC, 0.2 g ETN, 0.15 g AP, and 0.02 g Pb(NTA)2 were dissolved in 20 mL of ethyl acetate mixed solvent, and 0.05 g diphenylamine (DPA) and 0.01 g 2,4-dinitrophenol (DNP) were added as a two-component stabilizer. The mixture was dissolved by ultrasonication in a water bath at 60 °C.

[0055] S5: Under the synergistic action of ultrasound and mechanical stirring, 0.6 g of surface-modified nB powder was added to the above solution three times to form a dispersed phase with a solid content of 15%. The continuous phase was then a 2% aqueous solution of sodium dodecylbenzenesulfonate, and the receiving phase was a deionized water solution containing 0.1% tris(hydroxymethyl)aminomethane;

[0056] S6: Under the control of the syringe pump, the continuous phase was pumped at a rate of 3.5 mL min -1 , the dispersed phase was heated at 0.05 mL min -1 The dispersed phase solution is sheared to form oil / water (O / W) droplets due to the interaction of the flow rate.

[0057] S7: After the droplets enter the receiving phase, stirring is performed to accelerate the diffusion of the solvent. The solidified microspheres are washed with deionized water three times and dried in a vacuum drying oven at 40 °C for 24 h.

[0058] Experimental results: See Table 1 for details

[0059] Table 1 Combustion performance of microspheres prepared in Example 1

[0060]

[0061] The double bond groups in KH-570 can form chemical crosslinks with N molecular chains, improving the interfacial bonding strength between nano-boron powder and the binder. Under the action of PEG-400, a flexible coating layer is formed on the surface of the nano-boron powder, inhibiting particle agglomeration and improving compatibility with the organic phase. In the composite fuel formed by nB, AP decomposes to produce O2 to supplement the oxygen balance of the system, forming an oxidation-reduction gradient distribution with ETN, while Pb(NTA)2 forms catalytic active sites on the surface of the microspheres, which can reduce the decomposition temperature of ETN and increase the combustion rate, producing a synergistic exothermic effect during combustion.

[0062] Comparative Example 1

[0063] This embodiment provides a method for preparing highly active energetic microspheres containing nano-boron powder, and the following implementation contents include:

[0064] Purpose of the experiment:

[0065] Preparation of high-activity energetic microspheres containing nano-boron powder.

[0066] Experimental materials:

[0067] KH-550, octadecylamine, Tween-80, 10% NaOH aqueous solution, nB, NC, diphenylamine (DPA), ethyl acetate, the continuous phase and receiving phase are 2% by mass sodium dodecylbenzenesulfonate in deionized water, KH-570, ammonium perchlorate (AP), 5-nitrotetrazoline lead (Pb(NTA)2)

[0068] Experimental steps:

[0069] S1: 0.5 g KH-550, 0.1 g octadecylamine, 0.1 g Tween-80, 0.05 g KH-570, and 0.03 g PEG-400 were added to a mixture of 10 mL of ethanol and water. The mixture was stirred magnetically in a 40°C water bath for 30 minutes to promote hydrolysis, and then allowed to stand for 1 hour to allow complete hydrolysis.

[0070] S2: The pH value of the mixed solution of S1 was adjusted to 9 with 10% NaOH aqueous solution, ultrasonicated for 30 minutes, and then allowed to stand at room temperature for 6 hours;

[0071] S3: Then, 1 g of nB was added to 10 mL of anhydrous ethanol, and the mixed solution in S2 was added dropwise. The mixture was magnetically stirred at a speed of 300 r / min for 12 hours, and then filtered and dried in a 50°C water bath to obtain modified nano-boron powder.

[0072] S4: 0.4 g NC, 0.15 g AP, and 0.02 g Pb(NTA)2 were dissolved in 20 mL of ethyl acetate mixed solvent, 0.05 g diphenylamine (DPA) and 0.01 g 2,4-dinitrophenol (DNP) were added as a two-component stabilizer, and sonicated in a water bath at 60 °C.

[0073] S5: Under the synergistic action of ultrasound and mechanical stirring, 0.6 g of surface-modified nB powder was added to the above solution three times to form a dispersed phase with a solid content of 15%. The continuous phase was then a 2% aqueous solution of sodium dodecylbenzenesulfonate, and the receiving phase was a deionized water solution containing 0.1% tris(hydroxymethyl)aminomethane;

[0074] S6: Under the control of the syringe pump, the continuous phase was pumped at a rate of 3.5 mL min -1 , the dispersed phase was heated at 0.05 mL min -1 The dispersed phase solution is sheared to form oil / water (O / W) droplets due to the interaction of the flow rate.

[0075] S7: After the droplets enter the receiving phase, stirring is performed to accelerate the diffusion of the solvent. The solidified microspheres are washed three times with deionized water and dried in a vacuum drying oven at 40°C for 24 hours to obtain nB / NC microspheres.

[0076] Experimental results: See Table 2 for details

[0077] Table 2 Combustion performance of microspheres prepared in Comparative Example 1

[0078]

[0079] Referring to Table 1, Comparative Example 1 lacks ETN, and the addition of ETN is reduced in S4. The maximum flame intensity, maximum pressure, boost speed, maximum combustion temperature and ignition delay time without ETN are significantly lower than those in Example 1.

[0080] Comparative Example 2

[0081] This embodiment provides a method for preparing highly active energetic microspheres containing nano-boron powder and F2602, and the following implementation contents include:

[0082] Purpose of the experiment:

[0083] Preparation of high-activity energetic microspheres containing nano-boron powder and F2602.

[0084] Experimental materials:

[0085] KH-550, octadecylamine, Tween-80, 10% NaOH aqueous solution, nB, F2602, diphenylamine (DPA), ethyl acetate, the continuous phase and receiving phase are 2% by mass sodium dodecylbenzenesulfonate in deionized water, KH-570, ammonium perchlorate (AP), 5-nitrotetrazoline lead (Pb(NTA)2)

[0086] Experimental steps:

[0087] S1: 0.5 g KH-550, 0.1 g octadecylamine, 0.1 g Tween-80, 0.05 g KH-570, and 0.03 g PEG-400 were added to a mixture of 10 mL of ethanol and water. The mixture was stirred magnetically in a 40°C water bath for 30 minutes to promote hydrolysis, and then allowed to stand for 1 hour to allow complete hydrolysis.

[0088] S2: The pH value of the mixed solution of S1 was adjusted to 9 with 10% NaOH aqueous solution, ultrasonicated for 30 minutes, and then allowed to stand at room temperature for 6 hours;

[0089] S3: Then, 1 g of nB was added to 10 mL of anhydrous ethanol, and the mixed solution in S2 was added dropwise. The mixture was magnetically stirred at a speed of 300 r / min for 12 hours, and then filtered and dried in a 50°C water bath to obtain modified nano-boron powder.

[0090] S4: 0.4 g F2602, 0.15 g AP, and 0.02 g Pb(NTA)2 were dissolved in 20 mL of ethyl acetate mixed solvent, and 0.05 g diphenylamine (DPA) and 0.01 g 2,4-dinitrophenol (DNP) were added as a two-component stabilizer. The mixture was dissolved by ultrasonication in a water bath at 60 °C.

[0091] S5: Under the synergistic action of ultrasound and mechanical stirring, 0.6 g of surface-modified nB powder was added to the above solution three times to form a dispersed phase with a solid content of 15%. The continuous phase was then a 2% aqueous solution of sodium dodecylbenzenesulfonate, and the receiving phase was a deionized water solution containing 0.1% tris(hydroxymethyl)aminomethane;

[0092] S6: Under the control of the syringe pump, the continuous phase was pumped at a rate of 3.5 mL min -1 , the dispersed phase was heated at 0.05 mL min -1 The dispersed phase solution is sheared to form oil / water (O / W) droplets due to the interaction of the flow rate.

[0093] S7: After the droplets enter the receiving phase, stirring is performed to accelerate the diffusion of the solvent. The solidified microspheres are washed three times with deionized water and dried in a vacuum drying oven at 40°C for 24 hours to obtain nB / F2602 microspheres.

[0094] Experimental results: See Table 3 for details

[0095] Table 3: Combustion performance of microspheres prepared in Comparative Example 2

[0096]

[0097] Referring to Table 3, in Comparative Example 2, F2602 is used to replace the NC in Comparative Example 1. Its performance in terms of maximum flame intensity, maximum pressure, boost speed, maximum combustion temperature and ignition delay time is significantly lower than that of Comparative Example 1, highlighting the role of NC in improving the performance of the system.

[0098] Comparative Example 3

[0099] This embodiment provides a method for preparing KH-550 modified nano-boron powder, and the following implementation contents include:

[0100] Purpose of the experiment:

[0101] Preparation of KH-550 modified nano-boron powder.

[0102] Experimental materials:

[0103] KH-550, octadecylamine, Tween-80, 10% NaOH aqueous solution, nB, KH-570, PEG-400.

[0104] Experimental steps:

[0105] S1: 0.5 g KH-550, 0.1 g octadecylamine, 0.1 g Tween-80, 0.05 g KH-57, and 0.03 g PEG-400 were added to a mixture of 10 mL of ethanol and water. The mixture was stirred magnetically in a 40°C water bath for 30 minutes to promote hydrolysis, and then allowed to stand for 1 hour to allow complete hydrolysis.

[0106] S2: The pH value of the mixed solution of S1 was adjusted to 9 with 10% NaOH aqueous solution, ultrasonicated for 30 minutes, and then allowed to stand at room temperature for 6 hours;

[0107] S3: Then add 1g of nB into 10mL of anhydrous ethanol, drop into the mixed solution in S2, and magnetically stir at a speed of 300r / min for 12 hours, then filter and dry in a 50℃ water bath to obtain modified nano-boron powder.

[0108] Experimental results:

[0109] This method is to prepare nB particles modified only with KH-550 and compare the sedimentation phenomenon therein.

[0110] In Tables 1, 2, and 3, the flame intensity, the change in pressure in the closed explosive device with time, the combustion flame temperature, and the ignition delay time were all tested using special instruments designed and manufactured by our unit. The testing unit was the Ordnance Industry Booster Performance Testing Center of North University of China.

[0111] It can be seen from the data in Tables 1, 2 and 3 that, in the flame luminous intensity data tested by the light intensity meter, the maximum value of the luminous intensity of the combustion flame of Example 1 is much higher than the maximum values of the luminous intensity of the combustion flame of Comparative Example 1 and Comparative Example 2.

[0112] It can be seen from the data in Tables 1, 2, and 3 that in the pressure data in the closed exploder tested by the pressure sensor, the maximum pressure and pressurization rate generated by the combustion of Example 1 are significantly higher than the maximum pressure and pressurization rate generated by the combustion of Comparative Examples 1 and 2, indicating that the nB / NC / ETN microspheres prepared in Example 1 burn more violently.

[0113] From the data in Tables 1, 2, and 3, it can be seen that in the combustion flame temperature data tested by a high-sensitivity thermal infrared camera, the combustion flame temperature of Example 1 is much higher than the combustion flame temperatures of Comparative Examples 1 and 2, indicating that the nB / NC / ETN microspheres prepared in Example 1 release higher heat during combustion.

[0114] From the data in Tables 1, 2, and 3, it can be seen that the ignition delay time of the nB / NC / ETN microspheres prepared in Example 1 is significantly shorter than the ignition delay time of the microspheres prepared in Comparative Examples 1 and 2, indicating that under the same ignition conditions, the nB / NC / ETN microspheres are more easily ignited.

[0115] Table 4: Vacuum stability test results of microspheres prepared in Example 1, Comparative Example 1 and Comparative Example 2

[0116]

[0117] The data in Table 4 show that the microspheres prepared in Example 1 and Comparative Example 2 have good thermal stability, all components do not decompose, and all components show good chemical compatibility, indicating that the appropriate addition of DPA during the preparation of the microspheres can basically inhibit the self-decomposition of NC and ETN during heating or storage. However, the vacuum stability of Comparative Example 1 is unqualified. This is because the neutralizer DPA is not added during the preparation of nB / NC microspheres in Comparative Example 1, resulting in partial decomposition of NC in a high temperature environment and the release of excessive gases. Therefore, if DPA is not added, the chemical compatibility between nB and NC is poor. In addition, the data in Table 4 show that in Comparative Example 2, although DPA is not added, nB has good chemical compatibility with fluororubber F2602. Therefore, the appropriate addition of the neutralizer DPA during the preparation of nB / NC / ETN microspheres in Example 1 is also an innovation of the present invention.

[0118] The present invention refers to Figure 1 It shows that the raw material nB powder used in Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 are all extremely small spherical particles with a particle size of about 30-50 nm.

[0119] The present invention refers to Figure 2 The results show that the nB / NC / ETN microspheres prepared in Example 1 have extremely high sphericity, no adhesion between the microspheres, very good dispersibility, very smooth surface, very uniform size, and a microsphere diameter of about 50 μm.

[0120] The present invention refers to Figure 3 The results show that the nB / NC / ETN microspheres prepared in Example 1 have five elements, namely C, N, O, B and Si, on their surface. In fact, there should also be hydrogen, but the EDS spectrum cannot detect hydrogen. A small amount of Si comes from KH-550. This result is consistent with the elements that should be contained in nB / NC / ETN microspheres.

[0121] The present invention refers to Figure 4 It shows that the nB / NC / ETN microspheres prepared in Example 1 are mainly a composite of amorphous nB and ETN crystals. The XRD pattern shows that nB and ETN are successfully composited together.

[0122] The present invention refers to Figure 5 This shows again that the nB / NC / ETN microspheres prepared in Example 1 have five elements on their surface: C, N, O, B, and Si. In fact, there should also be hydrogen, but the XPS spectrum cannot detect hydrogen. A small amount of Si comes from KH-550. This result is consistent with the elements that should be contained in nB / NC / ETN microspheres.

[0123] The present invention refers to Figure 6-8 It shows that the combustion flame of the nB / NC / ETN microspheres prepared in Example 1 is the largest and brightest, which means that its combustion process is much more intense than that of the microspheres prepared in Comparative Examples 1 and 2.

[0124] The present invention refers to Figure 9 It shows that in a closed detonator, under the same ignition conditions, the nB / NC / ETN microspheres prepared in Example 1 are ignited first, and the pressure generated by their combustion is much higher than the pressure generated by the combustion of the microspheres prepared in Comparative Examples 1 and 2, which indicates that the nB / NC / ETN microspheres prepared in Example 1 have the highest reactivity.

[0125] The present invention refers to Figure 10It shows that under the conditions of constant pressure and the same ignition, the temperature of the combustion flame of the nB / NC / ETN microspheres prepared in Example 1 is much higher than the combustion flame temperature of the microspheres prepared in Comparative Examples 1 and 2, indicating that the nB / NC / ETN microspheres prepared in Example 1 release the most heat during combustion.

[0126] The present invention refers to Figure 11 It shows that the same mass of raw material nB powder, nB modified by Example 1 and Comparative Example 3 were placed in the same glass bottle, and 40 ml of ethyl acetate was added to each of the three glass bottles. After the bottle caps were closed, they were placed in a strong ultrasonic generator and ultrasonicated for 72 hours. Then the ultrasonication was stopped and the three bottles were left standing for 3 months under the same conditions to obtain Figure 11 The experimental results. Figure 11 The results show that the modified nB particles in Example 1 showed virtually no sedimentation; the modified nB particles in Comparative Example 3 exhibited significant partial sedimentation; and the raw nB, which had not undergone any surface modification, completely settled at the bottom of the bottle after three months of stagnant standing. This demonstrates that the modified nB particles in Example 1 exhibit the best dispersibility in ethyl acetate, making them particularly suitable for the subsequent microsphere preparation method. Therefore, the composite modifier consisting of KH-550, octadecylamine, and Tween-80 exhibits excellent modification effects, which is a key innovation of the present invention.

Claims

1. A high-activity energetic microsphere containing nano-boron powder and ETN, characterized in that: Comprises the following weight parts: 0.5-1g γ-aminopropyltriethoxysilane (KH-550), 0.1-0.2g octadecylamine, 0.1-0.2g Tween-80, 1-2g nB, 0.2-0.3g high-energy adhesive nitrocellulose (NC), 0.2-0.3g 1,2,3,4-butanetetrol tetranitrate (ETN), 0.05-0.1g diphenylamine (DPA), 0.05-0.1g KH-570, 0.15-0.2g ammonium perchlorate (AP), 0.02-0.1g 5-nitrotetrazolyl lead (Pb(NTA)2), 0.01-0.05g 2,4-dinitrophenol (DNP), 0.03-0.1g polyethylene glycol 400 (PEG-400).

2. The high-activity energetic microspheres containing nano-boron powder and ETN as claimed in claim 1, characterized in that: The microspheres are formed by uniformly mixing nano boron powder, ETN and NC.

3. The high-activity energetic microspheres containing nano-boron powder and ETN according to claim 1, characterized in that: The introduced ETN acts as a plasticizer of NC, improves the physical and mechanical properties of the nB microspheres, and accelerates the energy release of the nB microspheres.

4. The high-activity energetic microspheres containing nano boron powder and ETN as claimed in claim 1, characterized in that: The binder NC and the high explosive ETN of the nB particles will decompose and burn before the nB is ignited, releasing extremely high-temperature oxygen to preheat and preactivate the nano-boron particles, thereby significantly improving the ignition and combustion performance of the nB.

5. The high-activity energetic microspheres containing nano boron powder and ETN as claimed in claim 1, characterized in that: The ignition temperature of the nano-boron (nB) is 500° C., which is lower than the ignition temperature of micro-boron (μB) of 2400° C., and the combustion rate of nB is 1000 times that of μB, and it can release a large amount of heat energy in a short time.

6. The high-activity energetic microspheres containing nano boron powder and ETN according to claim 1, characterized in that: The DPA in the system inhibits the decomposition of NC in a high-temperature environment, reduces gas release, and improves the chemical compatibility of nB and NC.

7. A method for preparing high-activity energetic microspheres containing nano-boron powder and ETN as claimed in claims 1-6, characterized in that: The following steps are involved: S1: 0.5 g KH-550, 0.1 g octadecylamine, 0.1 g Tween-80, 0.05 g KH-570, and 0.03 g PEG-400 were added to 10 mL of a 3:1 ethanol / water mixture, and the mixture was stirred magnetically in a 40°C water bath for 30 minutes to promote hydrolysis. The mixture was allowed to stand for 1 hour to allow complete hydrolysis. S2: The pH of the mixed solution of S1 was adjusted with a 10% NaOH aqueous solution, and then allowed to stand at room temperature; S3: Then add 1g of nB to 10mL of anhydrous ethanol, dropwise add the mixed solution in S2, stir, filter, and dry to obtain modified nano-boron powder; S4: 0.2 g NC, 0.2 g ETN, 0.15 g AP, and 0.02 g Pb(NTA)2 were dissolved in 20 mL of ethyl acetate mixed solvent, and 0.05 g diphenylamine (DPA) and 0.01 g 2,4-dinitrophenol (DNP) were added as a two-component stabilizer, and dissolved by ultrasonication at 60 °C. S5: Under the synergistic action of ultrasound and mechanical stirring, 0.6 g of surface-modified nB powder was added to the above solution three times to form a dispersed phase with a solid content of 15%. The continuous phase was then a 2% aqueous solution of sodium dodecylbenzenesulfonate, and the receiving phase was a deionized water solution containing 0.1% tris(hydroxymethyl)aminomethane; S6: Under the control of the syringe pump, the continuous phase and the dispersed phase interact with each other, and the dispersed phase solution is sheared to form oil / water (O / W) droplets; S7: After the droplets enter the receiving phase, stirring is performed to accelerate the diffusion of the solvent. The solidified microspheres are washed three times with deionized water and then dried in a vacuum drying oven at 40°C to obtain nB / NC / ETN microspheres.

8. The high-activity energetic microspheres containing nano-boron powder and ETN according to claim 7, characterized in that: The pH of the S2 was adjusted to 9-10 and ultrasonically dispersed at 200 KHz for 30 minutes, and finally allowed to stand at room temperature for 6 hours.

9. The high-activity energetic microspheres containing nano-boron powder and ETN according to claim 7, characterized in that: The magnetic stirring in S3 was carried out at 300 r / min for 12 hours, and then dried at 50°C.

10. The high-activity energetic microspheres containing nano-boron powder and ETN according to claim 7, characterized in that: In S6, the continuous phase needs to be controlled at 3.5 mL min -1 , the dispersed phase was heated at 0.05 mL min -1 flow rate interactions.

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