High-combustion-efficiency agglomerated boron particles and preparation method thereof

Abstract

The invention relates to a preparation method of agglomerated boron particles with high combustion efficiency, which comprises the following steps: dissolving a dissolved high-nitrogen energetic compound solution in a binder mixed solution, sequentially adding a fluorine-containing functional compound and boron powder, carrying out centrifugal spray drying treatment, and collecting and depositing to obtain the agglomerated boron particles. The obtained agglomerated boron particles are solid spherical particles with the diameter of 5-50 [mu] m, the combustion efficiency of the agglomerated boron particles is 63.55%-77.01%, and the mass calorific value is 31.44-37.51 MJ / kg. According to the method, raw materials are easy to obtain, the process is simple and convenient, safety is high, large-scale preparation can be achieved, the combustion efficiency of the obtained agglomerated boron particles is improved by 16.67 MJ / kg, and meanwhile the process adaptability and comprehensive performance of the boron-containing fuel-rich solid propellant are effectively improved.

Description

Technical Field

[0001] The present invention relates to the field of rocket engine propulsion fuel preparation, in particular to a preparation method of solid oxygen-deficient propellant and the propellant. Background Art

[0002] The solid rocket ramjet engine is a power device based on the secondary combustion of a gas generator and air. It achieves efficient thrust output by mixing and burning the rich fuel gas in the gas generator and the air in the intake duct in the afterburning chamber.

[0003] In the field of solid oxygen-depleted propellants, boron (B) is considered a core fuel component due to its excellent thermodynamic properties: its mass heat of combustion reaches 58.28 MJ / kg (approximately 2.3 times and 1.9 times that of magnesium and aluminum, respectively), and its volume calorific value reaches 136.38 kJ / cm³ (approximately 3.09 times and 1.66 times that of magnesium and aluminum, respectively), significantly outperforming traditional metal fuels. Research has shown that when 40% boron powder is added to an oxygen-depleted propellant based on ammonium perchlorate (AP) / hydroxy-terminated polybutadiene (HTPB), the theoretical specific impulse can reach 12 kN·s / kg, a 5-6-fold increase over conventional propellants. Therefore, boron-based propellants hold significant potential for application in solid rocket ramjets and powder ramjets.

[0004] However, the existing boron-containing propellant technology still has the following key bottlenecks: the high melting point (2450 K) and high boiling point (3931 K) of boron make it easy to form a low melting point (718 K) oxide layer on its surface during combustion ( or (BO) n The oxide layer, which molten at high temperatures, coats the boron particles, hindering oxygen diffusion and further oxidation of the core, significantly reducing combustion efficiency and the energy release rate in the afterburner. While amorphous boron powder possesses a high specific surface area, its surface active sites readily react with propellant binders (such as HTPB), leading to a decrease in the propellant's curing and crosslinking degree and deteriorating storage stability. This severely limits the actual amount of boron powder added (typically requiring less than 30%) and restricts energy density gains. These issues make it difficult for existing boron-containing propellants to achieve both high energy density and stable combustion performance, a core challenge hindering the development of solid rocket ramjet technology.

[0005] In order to improve the combustion performance and process performance of boron powder in ramjet engines, agglomeration and granulation of boron powder is an effective method. The Chinese patent application with publication number CN 101531556 B provides a method for kneading and granulating boron powder with a liquid polyurethane adhesive prepolymer (such as HTPB); the Chinese patent application with publication number CN101805238A proposes a preparation method by premixing boron powder and then extruding and screening. The agglomerated boron particles obtained by the above methods improve the performance of boron powder to a certain extent, but all use prepolymer as a binder, and a curing agent with certain toxicity needs to be added during the granulation process for curing and forming, resulting in a more complicated process. Secondly, Chinese patent application CN 109574775 A proposes a method for preparing highly reactive agglomerated boron particles by agglomerating polyvinylidene fluoride (PVDF) and boron powder via electrospinning. However, this method is relatively complex and difficult to mass-produce. The fibrous product is bulky and loose, potentially resulting in a low charge density. Furthermore, its application in practical propellants requires ensuring uniform mixing of the fibers and the matrix. Summary of the Invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for preparing agglomerated boron particles with high combustion efficiency, which is non-toxic, highly safe, suitable for large-scale preparation and low cost.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing agglomerated boron particles with high combustion efficiency, comprising the following steps: Step 1: Mixing the binder and the first solvent at a mass ratio of 1:50-100 at a temperature of 80-95° C. and stirring until uniform, to obtain a mixed solution; Wherein, the binder is polyvinyl alcohol or polyvinylidene fluoride or GAP glycidyl azide polymer; the first solvent is deionized water or dimethyl sulfoxide or N,N-dimethylformamide; Too high a binder content increases the viscosity of the mixed solution, affecting the subsequent full dissolution of high-nitrogen energetic compounds, which is not conducive to the formation of spherical particles.

[0008] Step 2: Under magnetic stirring at a temperature of 80-95°C, the high nitrogen energetic compound is completely dissolved in the second solvent determined according to the properties of the high nitrogen compound, and then the dissolved high nitrogen energetic compound solution is dissolved in the mixed solution to obtain a clear A solution. The mass ratio of the high nitrogen energetic compound to the second solvent is 1-10:1000, and the mass ratio of the second solvent to the mixed liquid is 50-100:1, so as to ensure that the calorific value of combustion reaches above 30MJ / kg. The temperature condition of 80~95℃ is used to increase the dissolution time of high nitrogen energetic compounds; When the amount of high-nitrogen energetic compounds added is too low, the combustion performance of the agglomerated boron particles cannot be effectively improved, resulting in a low calorific value; while when the amount added is too high, there is a problem of limited solubility and may cause uneven structure, which is also not conducive to the improvement of combustion calorific value.

[0009] Step 3: Add the fluorine-containing functional compound to solution A while continuing to stir magnetically. After the fluorine-containing functional compound is completely dissolved, add boron powder to obtain solution B. The mass ratio of the fluorine-containing functional compound to the A solution is 1-8:1000, the mass ratio of the boron powder to the high nitrogen energetic compound is 100:1-45, and the mass ratio of the boron powder to the fluorine-containing functional compound is 100:1-30. The fluorine-containing functional compound is used to promote the uniform balling of the agglomerated boron particles and is also used to generate hydrogen fluoride gas during the combustion process to react with the oxide film on the surface of the boron, thereby removing the oxide layer on the surface of the agglomerated boron particles; Therefore, the amount of fluorine-containing functional compounds added needs to be reasonably controlled. Too high an amount may lead to insufficient solubility in solution A and reduce the relative content of boron, thereby reducing the energy density of the agglomerated particles. Too low an amount will affect the pelletizing quality and structural uniformity of the agglomerated boron particles, and will not be conducive to improving the combustion efficiency of the agglomerated boron particles, resulting in a low calorific value. Boron powder is used to increase the energy density of agglomerated boron particles and improve energy release and combustion performance; too low a boron powder content will reduce the energy density of agglomerated boron particles, which is not conducive to improving the energy release and combustion performance of agglomerated boron particles.

[0010] Step 4: subjecting the B solution to centrifugal spray drying and collecting the sediment to obtain agglomerated boron particles.

[0011] Furthermore, in step 1, the molecular weight of the polyvinyl alcohol is 10,000-50,000, and the alcoholysis degree is 88%.

[0012] Furthermore, in the step 1, the binder and the solvent are mixed uniformly at a stirring speed of 500-700 r / min.

[0013] Furthermore, the high nitrogen energetic compound and the corresponding second solvent described in step 2 are: 2,4,6-triamino-5-nitropyrimidine-1,3-dioxide (ICM-102), the corresponding second solvent is water; or 3,3′-diamino-4,4′-azofuroxan (DAAF), and the corresponding second solvent is N,N-dimethylformamide (DMF); or 4-amino-3,5-dinitropyrazole (LLM-116), the corresponding second solvent is N,N-dimethylformamide (DMF); or 2,2'-dinitro-5,5'-diazolyl (DNNA), and the corresponding second solvent is N,N-dimethylformamide (DMF); Or melamine dinitrogen oxide (TTDO), the corresponding second solvent is water.

[0014] Furthermore, in step 2, the mass ratio of the high nitrogen energetic compound to the second solvent is 6:1000.

[0015] Furthermore, the fluorine-containing functional compound described in step three is one of perfluorooctanoic acid, perfluoroheptanoic acid, perfluoropentanoic acid, perfluorononanoic acid, undecanoic acid, perfluoropolyether, and 3-(perfluorohexanoic acid)-1,2-propylene oxide.

[0016] Furthermore, in step three, the mass ratio of the fluorine-containing functional compound to solution A is 3:1000, the mass ratio of boron powder to the high-nitrogen energetic compound is 100:25, and the mass ratio of boron powder to the fluorine-containing functional compound is 100:15.

[0017] Furthermore, the centrifugal spray drying process described in step 4 is specifically as follows: The centrifugal atomizer (2) sprays the B solution from the top of the drying tower (3) into the drying tower (3) at a pressure of 1100-1300 kPa at a centrifugal frequency of 25 Hz-30 Hz. After the droplets with a particle size of less than 50 μm come into contact with the high-temperature gas with a temperature of 95-150°C in the cavity of the drying tower (3), the water in the droplets is rapidly vaporized, causing the solid components to be deposited on the surface of the reaction cavity of the drying tower (3). Then, the drying tower (3) is knocked and collected using an air hammer, thereby obtaining dry, micron-sized agglomerated boron particles with high combustion efficiency.

[0018] The temperature is 95-150°C, preferably 120°C, and the pressure is 1100-1300 kPa, preferably 1200 kPa. Too low a temperature will result in poor sample drying, while too high a temperature may cause decomposition of the binder or fluorinated functional compound. Furthermore, improper pressure settings (too high or too low) during the spray drying process may also pose safety risks to equipment operation.

[0019] Furthermore, the B solution is delivered to the centrifugal atomizer via a peristaltic pump; At the same time, the high-temperature gas in the drying tower is nitrogen, which is used to protect the agglomerated boron particles obtained in the reaction chamber of the drying tower from oxidation. The nitrogen is heated by a heater and then sent into the drying tower; a discharge port is provided at the bottom of the drying tower, and a discharge valve is also provided at the discharge port.

[0020] The present invention also provides agglomerated boron particles obtained using the preparation method of high-combustion-efficiency agglomerated boron particles as described above. The agglomerated boron particles are solid spherical particles with a diameter of 5 to 50 μm, a combustion efficiency of 63.55% to 77.01%, and a mass calorific value of 31.44 to 37.51 MJ / kg.

[0021] The beneficial effects of the present invention are: (1) The spray drying method is used to prepare agglomerated boron particles with high combustion efficiency. The raw materials are easily available, the process is simple, the safety is high, and large-scale production can be achieved. (2) By introducing fluorine-containing functional compounds and binders, the problem of poor adhesion between high-nitrogen energetic compounds and amorphous boron powder was effectively overcome; The binder used is polyvinyl alcohol, which can undergo a cross-linking reaction with the boric acid on the surface of the boron powder, enhancing the structural stability of the agglomerated particles and improving the compatibility between the boron powder and other components in the solid propellant. (3) The prepared agglomerated boron particles have uniform particle size distribution and good structural stability. The synergistic effect of high-nitrogen energetic compounds and fluorine-containing functional compounds significantly improves the ignition performance and combustion efficiency of boron powder, making the combustion efficiency of the prepared agglomerated boron particles reach 31.44~37.51 MJ / kg, an increase of 16.67 MJ / kg, and at the same time improves the process adaptability and comprehensive performance of boron-containing fuel-rich solid propellants. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the spray drying method for preparing agglomerated boron particles with high combustion efficiency.

[0023] Figure 2 This is a scanning electron microscope image of the high combustion efficiency agglomerated boron particles synthesized in specific example 4. DETAILED DESCRIPTION

[0024] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0025] In order to achieve the above object, the present invention provides the following specific implementation methods: Example 1: Figure 1 As shown, a method for preparing agglomerated boron particles with high combustion efficiency comprises the following steps: Step 1: Mixing the binder and the first solvent at a mass ratio of 1:50-100 at a temperature of 80-95° C. and stirring until uniform at a stirring speed of 500-700 r / min to obtain a mixed solution; Wherein, the binder is polyvinyl alcohol or polyvinylidene fluoride or GAP glycidyl azide polymer; the first solvent is deionized water or dimethyl sulfoxide or N,N-dimethylformamide; Step 2: Under magnetic stirring at a temperature of 80-95°C, the high nitrogen energetic compound is completely dissolved in the second solvent determined according to the properties of the high nitrogen compound, and then the dissolved high nitrogen energetic compound solution is dissolved in the mixed solution to obtain a clear A solution. The mass ratio of the high nitrogen energetic compound to the second solvent is 1-10:1000, and the mass ratio of the second solvent to the mixed liquid is 50-100:1, so as to ensure that the calorific value of combustion reaches above 30MJ / kg. Step 3: Add the fluorine-containing functional compound to solution A while continuing to stir magnetically. After the fluorine-containing functional compound is completely dissolved, add boron powder to obtain solution B. The mass ratio of the fluorine-containing functional compound to the A solution is 1-8:1000, the mass ratio of the boron powder to the high nitrogen energetic compound is 100:1-45, and the mass ratio of the boron powder to the fluorine-containing functional compound is 100:1-30. The fluorine-containing functional compound is used to promote the uniform balling of the agglomerated boron particles and is also used to generate hydrogen fluoride gas during the combustion process to react with the oxide film on the surface of the boron, thereby removing the oxide layer on the surface of the agglomerated boron particles; Boron powder is used to increase the energy density of agglomerated boron particles, improve energy release and combustion performance; The fluorine-containing functional compound is one of perfluorooctanoic acid, perfluoroheptanoic acid, perfluoropentanoic acid, perfluorononanoic acid, undecanoic acid, perfluoropolyether, and 3-(perfluorohexanoic acid)-1,2-propylene oxide; Step 4: centrifugal spray drying the B solution, collecting the sediment to obtain agglomerated boron particles; Among them, Figure 1 As shown, centrifugal spray drying treatment is specifically: Solution B is delivered to the centrifugal atomizer 2 via a peristaltic pump 1. The centrifugal atomizer 2 sprays solution B from the top of the drying tower 3 into the drying tower 3 at a pressure of 1100-1300 kPa at a centrifugal frequency of 25 Hz-30 Hz. The formed droplets with a particle size of less than 50 μm come into contact with the high-temperature nitrogen gas at a temperature of 95-150°C in the cavity of the drying tower 3. The water in the droplets rapidly vaporizes, causing the solid components to be deposited on the surface of the reaction cavity of the drying tower 3. The drying tower 3 is then struck and collected using an air hammer. A discharge port 5 is provided at the bottom of the drying tower 3, and a discharge valve 6 is also provided at the discharge port. Opening the discharge valve 6 yields dry, micron-sized agglomerated boron particles with high combustion efficiency.

[0026] The nitrogen is used to protect the agglomerated boron particles from being oxidized in the reaction chamber of the drying tower 3 . The nitrogen is heated by the heater 4 and then fed into the drying tower 3 .

[0027] Example 2: The same as Example 1, except that the binder in step 1 is polyvinyl alcohol, the molecular weight of the polyvinyl alcohol is 10,000-50,000, and the degree of alcoholysis is 88%.

[0028] Example 3: The same as Example 1, except that the high nitrogen energetic compound and the corresponding second solvent in step 2 are: 2,4,6-triamino-5-nitropyrimidine-1,3-dioxide (ICM-102), the corresponding second solvent is water; The mass ratio of the high-nitrogen energetic compound to the second solvent is 1:1000, and the mass ratio of the second solvent to the mixed liquid is 50:1.

[0029] Example 4: The same as Example 1, except that the high nitrogen energetic compound and the corresponding second solvent in step 2 are 3,3′-diamino-4,4′-azofurazan (DAAF), and the corresponding second solvent is N,N-dimethylformamide (DMF); The mass ratio of the high nitrogen energetic compound to the second solvent is 3:1000, and the mass ratio of the second solvent to the mixed solution is 50:1. Example 5: The same as Example 1, except that the high nitrogen energetic compound and the corresponding second solvent in step 2 are: 4-amino-3,5-dinitropyrazole (LLM-116), and the corresponding second solvent is N,N-dimethylformamide (DMF); The mass ratio of the high nitrogen energetic compound to the second solvent is 6:1000, and the mass ratio of the second solvent to the mixed solution is 50:1. Example 6: The same as Example 1, except that the high nitrogen energetic compound and the corresponding second solvent in step 2 are 2,2'-dinitro-5,5'-diazolyl (DNNA), and the corresponding second solvent is N,N-dimethylformamide (DMF); The mass ratio of the high nitrogen energetic compound to the second solvent is 8:1000, and the mass ratio of the second solvent to the mixed solution is 60:1. Example 7: The same as Example 1, except that the high-nitrogen energetic compound and the corresponding second solvent in step 2 are melamine dinitrogen oxide (TTDO), and the corresponding second solvent is water.

[0030] The mass ratio of the high-nitrogen energetic compound to the second solvent is 9:1000, and the mass ratio of the second solvent to the mixed liquid is 70:1.

[0031] Example 8: The same as Example 1, except that in step 2, the mass ratio of the high nitrogen energetic compound to the second solvent is 6:1000.

[0032] Example 9: The same as Example 1, except that the mass ratio of the fluorine-containing functional compound to solution A is 3:1000, the mass ratio of boron powder to high nitrogen energetic compound is 80:20, and the mass ratio of boron powder to fluorine-containing functional compound is 100:15.

[0033] Example 10: The same as Example 1, except that the fluorine-containing functional compound is perfluorooctanoic acid; the mass ratio of the fluorine-containing functional compound to solution A is 1:1000.

[0034] Example 11: The same as Example 1, except that the fluorine-containing functional compound is perfluoroheptanoic acid; the mass ratio of the fluorine-containing functional compound to solution A is 2:1000.

[0035] Example 12: The same as Example 1, except that the fluorine-containing functional compound is perfluoropentanoic acid; the mass ratio of the fluorine-containing functional compound to solution A is 3:1000.

[0036] Example 13: The same as Example 1, except that the fluorine-containing functional compound is perfluorononanoic acid; the mass ratio of the fluorine-containing functional compound to solution A is 4:1000.

[0037] Example 14: The same as Example 1, except that the fluorine-containing functional compound is undecafluorohexanoic acid; the mass ratio of the fluorine-containing functional compound to solution A is 5:1000.

[0038] Example 15: The same as Example 1, except that the fluorine-containing functional compound is perfluoropolyether; the mass ratio of the fluorine-containing functional compound to solution A is 6:1000.

[0039] Example 16: The same as Example 1, except that the fluorine-containing functional compound is 3-(perfluorohexanoic acid)-1,2-propylene oxide; the mass ratio of the fluorine-containing functional compound to solution A is 8:1000.

[0040] Example 17: The present invention also provides agglomerated boron particles obtained using the preparation method of high-combustion-efficiency agglomerated boron particles as described above, wherein the agglomerated boron particles are solid spherical particles with a diameter of 5 to 50 μm, the combustion efficiency of the agglomerated boron particles is 63.55% to 77.01%, and the mass calorific value is 31.44 to 37.51 MJ / kg.

[0041] like Figure 2 In order to further illustrate the technical solutions and effects of the present invention, the following specific examples are provided: Specific example 1: The method for preparing agglomerated boron particles with high combustion efficiency according to the present invention comprises the following steps: Step 1: Mix a binder and a solvent in a certain proportion at high temperature and stir thoroughly to achieve uniform dissolution. Polyvinyl alcohol is preferably used as the binder, and the solvent is water or N,N-dimethylformamide. The mass ratio of polyvinyl alcohol to solvent is 1:100, and the stirring temperature is 90°C. The solvent can be selected based on the solubility properties of different high-nitrogen energetic compounds.

[0042] Step 2: Add a certain amount of high-nitrogen energetic compound to step 1, stir magnetically until completely dissolved, and the solution becomes yellow and clear. The mass ratio of high-nitrogen energetic compound to water is (6:1000); Step 3, adding an appropriate amount of treated amorphous boron powder to step 2 and performing magnetic stirring, wherein the mass ratio of boron powder to high nitrogen energetic compound is 100:25; Step 4: centrifugally spray-dry the solution obtained in step 3 at 120° C., and collect the collected boron particles to obtain agglomerated boron particles with high combustion efficiency.

[0043] The diameters of the prepared boron composite microspheres modified with different high-nitrogen energetic compounds range from 25 μm to 50 μm.

[0044] Table 1 is a performance table of high combustion efficiency agglomerated boron particles synthesized in Example 1. Table 1

[0045] Note: The mass calorific value of the sample is measured by an oxygen bomb calorimeter in a 3MPa pure oxygen environment.

[0046] From the above results, it can be seen that DAAF and ICM-102 (Specific Example 1) are more effective in improving the combustion efficiency of boron powder.

[0047] Specific example 2: On the basis that other conditions are the same as those in Specific Example 1, the mass ratio of boron powder to high nitrogen energetic compound is adjusted as a variable to investigate the effect of different B powder / DAAF and ICM-102 mass ratios on the performance of agglomerated boron particles. The experimental results are shown in Table 2, which shows the effect of different B powder / DAAF or ICM-102 mass ratios on the performance of agglomerated boron particles.

[0048] Table 2

[0049] From the above results, it can be seen that with the increase of high-nitrogen energetic compounds, the combustion efficiency of boron powder is more significantly improved. However, since an excessive amount of high-nitrogen energetic compounds will limit the energy density of the boron-containing fuel-rich propellant, the preferred mass ratio of high-nitrogen energetic compounds to B powder is 100:15 (Specific Example 2).

[0050] Specific example 3: On the basis that other conditions are the same as those in Specific Example 1, step three is changed to: add a certain amount of perfluorooctanoic acid to the solution obtained in step 2, and the mass ratio of water to perfluorooctanoic acid is 1000:3. After the perfluorooctanoic acid is completely dissolved, add an appropriate amount of pretreated amorphous boron powder and perform magnetic stirring to fully disperse it. The mass ratio of boron powder to DAAF and ICM-102 is 100:15, and the mass ratio of boron powder to perfluorooctanoic acid is shown in Table 3. Through this design, the purpose is to investigate the effect of different fluorine-containing functional compounds on the performance of high-nitrogen energetic compound modified boron powder. The relevant experimental results are shown in Table 3, which shows the effect of different fluorine-containing functional compounds on the performance of high-nitrogen energetic compound modified B powder.

[0051] Table 3

[0052] From the above results, it can be seen that perfluorooctanoic acid is preferably used as the surfactant (Specific Example 3), which can more significantly improve the combustion efficiency of boron powder.

[0053] Specific example 4: On the basis of other conditions being the same as those in Example 3, the effect of the mass ratio of ICM-102 modified boron powder to perfluorooctanoic acid on the combustion performance of agglomerated boron particles was further investigated. Figure 2 As shown in the figure, the particle size distribution of ICM-102 modified agglomerated boron particles is relatively uniform.

[0054] Table 4 shows the effect of the mass ratio of ICM-102 modified boron powder to perfluorooctanoic acid on the combustion performance of agglomerated boron particles. It lists the ignition performance of the boron powder in an air atmosphere before and after agglomeration (ignition time was determined by combined testing with a spectrometer and a high-speed camera) as well as the calorific value measurement results in an oxygen bomb environment.

[0055] Table 4

[0056] The above results show that as the PFOA content increases, the ignition performance and combustion efficiency of the modified B powder improve. Since an excessive amount of PFOA will limit the energy density of the boron-rich fuel propellant, the preferred mass ratio of PFOA to B powder is 17.6:100 (Specific Example 2).

[0057] This invention uses a high-nitrogen energetic compound as the coating material, a fluorine-containing functional compound as the surfactant, and a polymer compound as the binder. This effectively addresses the problem of poor coating efficiency of boron powder with high-nitrogen energetic compounds, while significantly improving the combustion performance of the agglomerated boron particles. The resulting agglomerated boron particles significantly enhance the combustion efficiency of boron powder and exhibit a uniform particle size distribution, with a diameter of 25 to 50 μm.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing agglomerated boron particles with high combustion efficiency, characterized in that: The following steps are involved: Step 1: Mixing the binder and the first solvent at a mass ratio of 1:50-100 at a temperature of 80-95° C. and stirring until uniform, to obtain a mixed solution; Wherein, the binder is polyvinyl alcohol or polyvinylidene fluoride or GAP glycidyl azide polymer; the first solvent is deionized water or dimethyl sulfoxide or N,N-dimethylformamide; Step 2: Under magnetic stirring at a temperature of 80-95°C, the high nitrogen energetic compound is completely dissolved in the second solvent determined according to the properties of the high nitrogen compound, and then the dissolved high nitrogen energetic compound solution is dissolved in the mixed solution to obtain a clear A solution. The mass ratio of the high nitrogen energetic compound to the second solvent is 1-10:1000, and the mass ratio of the second solvent to the mixed liquid is 50-100:1, so as to ensure that the calorific value of combustion reaches above 30MJ / kg. Step 3: Add the fluorine-containing functional compound to solution A while continuing to stir magnetically. After the fluorine-containing functional compound is completely dissolved, add boron powder to obtain solution B. The mass ratio of the fluorine-containing functional compound to the A solution is 1-8:1000, the mass ratio of the boron powder to the high nitrogen energetic compound is 100:1-45, and the mass ratio of the boron powder to the fluorine-containing functional compound is 100:1-30. The fluorine-containing functional compound is used to promote the uniform balling of the agglomerated boron particles and is also used to generate hydrogen fluoride gas during the combustion process to react with the oxide film on the surface of the boron, thereby removing the oxide layer on the surface of the agglomerated boron particles; Boron powder is used to increase the energy density of agglomerated boron particles, improve energy release and combustion performance; Step 4: subjecting the B solution to centrifugal spray drying and collecting the sediment to obtain agglomerated boron particles.

2. The method for preparing agglomerated boron particles with high combustion efficiency according to claim 1, wherein: In step 1, the molecular weight of the polyvinyl alcohol is 10,000-50,000, and the alcoholysis degree is 88%.

3. The method for preparing agglomerated boron particles with high combustion efficiency according to claim 1, wherein: In the step 1, the binder and the solvent are uniformly mixed at a stirring speed of 500-700 r / min.

4. The method for preparing agglomerated boron particles with high combustion efficiency according to claim 1, wherein: The high nitrogen energetic compound and the corresponding second solvent described in step 2 are: 2,4,6-triamino-5-nitropyrimidine-1,3-dioxide (ICM-102), the corresponding second solvent is water; or 3,3′-diamino-4,4′-azofuroxan (DAAF), and the corresponding second solvent is N,N-dimethylformamide (DMF); or 4-amino-3,5-dinitropyrazole (LLM-116), the corresponding second solvent is N,N-dimethylformamide (DMF); or 2,2'-dinitro-5,5'-diazolyl (DNNA), and the corresponding second solvent is N,N-dimethylformamide (DMF); Or melamine dinitrogen oxide (TTDO), the corresponding second solvent is water.

5. The method for preparing agglomerated boron particles with high combustion efficiency according to claim 1, wherein: In step 2, the mass ratio of the high nitrogen energetic compound to the second solvent is 6:1000.

6. The method for preparing agglomerated boron particles with high combustion efficiency according to claim 1, wherein: The fluorine-containing functional compound described in step three is one of perfluorooctanoic acid, perfluoroheptanoic acid, perfluoropentanoic acid, perfluorononanoic acid, undecanoic acid, perfluoropolyether, and 3-(perfluorohexanoic acid)-1,2-propylene oxide.

7. The method for preparing agglomerated boron particles with high combustion efficiency according to claim 1, wherein: In step 3, the mass ratio of the fluorine-containing functional compound to solution A is 3:1000, the mass ratio of boron powder to the high-nitrogen energetic compound is 100:25, and the mass ratio of boron powder to the fluorine-containing functional compound is 100:

15.

8. The method for preparing agglomerated boron particles with high combustion efficiency according to any one of claims 1 to 7, characterized in that: The centrifugal spray drying process described in step 4 is specifically as follows: The centrifugal atomizer (2) sprays the B solution from the top of the drying tower (3) into the drying tower (3) at a pressure of 1100-1300 kPa at a centrifugal frequency of 25 Hz-30 Hz. After the droplets with a particle size of less than 50 μm come into contact with the high-temperature gas with a temperature of 95-150°C in the cavity of the drying tower (3), the water in the droplets is rapidly vaporized, causing the solid components to be deposited on the surface of the reaction cavity of the drying tower (3). Then, the drying tower (3) is knocked and collected using an air hammer, thereby obtaining dry, micron-sized agglomerated boron particles with high combustion efficiency.

9. The method for preparing agglomerated boron particles with high combustion efficiency according to claim 8, characterized in that: The solution B is delivered to the centrifugal atomizer (2) via a peristaltic pump (1); At the same time, the high-temperature gas in the drying tower (3) is nitrogen, which is used to protect the agglomerated boron particles obtained in the reaction chamber of the drying tower (3) from being oxidized. The nitrogen is heated by the heater (4) and then fed into the drying tower (3). A discharge port (5) is provided at the bottom of the drying tower (3), and a discharge valve (6) is also provided at the discharge port.

10. Agglomerated boron particles obtained by the method for preparing agglomerated boron particles with high combustion efficiency according to claims 1 to 9, characterized in that: The agglomerated boron particles are solid spherical particles with a diameter of 5 to 50 μm. The combustion efficiency of the agglomerated boron particles is 63.55% to 77.01%, and the mass calorific value is 31.44 to 37.51 MJ / kg.

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