Low-cost high-calorific-value boron-containing aluminum-based composite fuel and preparation method thereof

Abstract

This invention discloses a low-cost, high-calorific-value boron-aluminum-based composite fuel and its preparation method. The low-cost, high-calorific-value boron-aluminum-based composite fuel, by mass percentage, consists of 75%–90% Al powder with a particle size of 1–50 μm, 0%–10% D... 50 =1~3μm B powder and 10%~20% D 50 Composed of ultrafine B4C powder with a particle size of ≤5μm. This invention prepares boron-aluminum based composite fuels with specific component ratios by partially or completely replacing amorphous boron powder with ultrafine B4C powder, using ultrasonic dispersion or mechanical ball milling techniques. This achieves high calorific value while effectively controlling raw material costs.

Description

Technical Field

[0001] This invention belongs to the field of aluminum-based metal fuels and relates to a low-cost, high-calorific-value boron-containing aluminum-based composite fuel and its preparation method. Background Technology

[0002] Compared to traditional hydrocarbon fuels, metallic fuels, represented by micron-sized aluminum (Al) powder, have become widely used as high-energy additives in energetic systems such as solid propellants, mixed explosives, and pyrotechnics due to their high calorific value and abundant raw materials. These additives enhance the energy density of the formulation, improve ignition and combustion behavior, and increase heat of explosion and destructive power. In recent years, boron has also gained attention due to its high mass and volumetric calorific values ​​(58.3 kJ / g, 136.4 kJ / cm³). 3 Boron has received widespread research and attention and is considered a metallic fuel with enormous application potential (although boron is a non-metal, it is generally classified as a metallic fuel in the industry based on its application range). In the field of solid propellants, the Meteor air-to-air missile, jointly developed by six European countries, achieved superior performance far exceeding that of existing missiles of the same type due to its successful use of a solid rocket ramjet engine with boron-rich propellant. The successful development of the Meteor missile and its demonstration effect sparked a surge in the research and development of boron-rich propellants in various countries. In the field of mixed explosives and pyrotechnics, although there are no publicly reported practical application cases, a large number of academic studies have shown that adding a certain amount of boron powder can increase the heat of explosion and underwater / airborne explosion energy of mixed explosives, and improve the ignition capability and radiation performance of pyrotechnic agents. For example, Chen Yuan et al. from Nanjing University of Science and Technology (Chen Yuan, Chen Xiang, Jiang Wei et al., Effect of Boron Content on Underwater Explosion Energy of Aluminum-Containing Explosives, Explosive Materials, 2015, 44: 1-4) studied the effect of different boron powder contents on the underwater explosion energy of aluminum-containing explosives (Al / B / AP / RDX / Wax). The results showed that when the boron powder content was 10%, the total underwater explosion energy and bubble energy were increased by 5% and 7% respectively compared with the corresponding mixed explosives without boron powder, reaching 5942 kJ / kg and 4999 kJ / kg; Nanjing University of Science and Technology Du Jun et al. (Du Jun, Guan Hua, Li Jie et al., Effect of Boron Powder Content on Combustion and Infrared Radiation Characteristics of KNO3 / Mg-Al Infrared Decoy, Energetic Materials, 2015, 23: 368-371) studied the effect of boron powder content on the radiation characteristics of potassium nitrate / aluminum-magnesium alloy-based infrared decoys. The results showed that the combustion temperature, radiance, and radiance intensity all increased continuously with the increase of boron powder content from 0% to 4%, reaching 1046.19℃ and 1681.59 W / m², respectively, when the boron powder content was 4%. 2 The sr and 2.64 W / sr are 43.76%, 68.89%, and 140% higher than boron-free formulations, respectively.

[0003] Although boron powder has shown potential as a high-energy metallic fuel to replace aluminum powder in the field of explosives, its application in engineering projects is greatly limited by technical bottlenecks such as difficulty in ignition, low combustion efficiency, and poor process compatibility, as well as its small industrial scale and high cost. Elemental boron does not exist in nature; it exists in the form of borates in minerals or brines. Boron-containing minerals are purified through a series of pyrometallurgical, hydrometallurgical, or reactive processes to produce products such as borax (Na2B4O7·10H2O), boric acid (H3BO3), boron oxide (B2O3), boron carbide (B4C), elemental boron (crystalline and amorphous boron), boron nitride (h-BN / c-BN), and borohydrides. Figure 3 As shown.

[0004] Currently, the large-scale production of elemental boron powder mainly adopts the magnesothermic reduction method (3Mg + B₂O₃ = 2B + 3MgO). The reduction products of boron oxide and magnesium powder are acid-leached, washed, and filtered to remove impurities such as MgO and B₂O₃. Finally, the product is dried to obtain amorphous boron powder with a boron content of about 85%. Further refining and purification can yield high-purity elemental boron powder. Due to the multi-step processing involved and the large amount of waste liquid generated in the process, the price of commercially available amorphous boron powder remains high, reaching 1700-2800 yuan / kg, which is much higher than that of conventional micronized aluminum powder (30-55 yuan / kg).

[0005] Boron carbide (B4C) is one of the main products of the boron industry. Due to its extremely high hardness, strength, and good neutron shielding properties, it is commonly used as a wear-resistant material, bulletproof armor material, and nuclear shielding material. The calorific value of B4C is 52.0 kJ / g, slightly lower than that of elemental boron (58.3 kJ / g), while its density is relatively high (2.52 g / cm³). 3 Its volumetric calorific value is comparable to that of boron (131.0 kJ / cm³). 3 vs. 136.4kJ / cm 3 Chinese patent application 201810930112.5 discloses a fuel-rich propellant formulation, which mentions a fuel for a fuel-rich propellant formulation composed of one or a combination of boron (B), magnesium (Mg), aluminum (Al), titanium (Ti), zirconium (Zr), boron carbide (B4C), and boron-based metal composites (B-Mg, B-Al, B-Ti). This fuel is a boron-based composite fuel, in which B and B4C with a particle size of 1-3 μm (the ratio of the two is not specified) are the main fuels, and industrial-grade metals (Mg, Al, Ti, Zr) with a particle size of 1-30 μm and boron-based metal composites are the auxiliary fuels. The raw material cost is still relatively high. Summary of the Invention

[0006] The purpose of this invention is to provide a low-cost, high-calorific-value boron-aluminum-based composite fuel and its preparation method. By partially or completely replacing amorphous boron powder with ultrafine B4C powder, a boron-aluminum-based composite fuel with a specific component ratio is prepared using ultrasonic dispersion or mechanical ball milling composite technology. This achieves high calorific value (>32.0 kJ / g) while effectively controlling raw material costs (<300 yuan / kg).

[0007] The technical solution for achieving the objective of this invention is as follows:

[0008] Low-cost, high-calorific-value boron-aluminum-based composite fuel, by mass percentage, consists of 75%–90% Al powder with a particle size of 1–50 μm and 0%–10% D. 50 = 1-3μm B powder and 10%-20% D 50 Composed of ultrafine B4C powder with a particle size of ≤5μm.

[0009] Preferably, the Al powder is spherical or flake-shaped.

[0010] Preferably, by mass percentage, it consists of 85%–90% Al powder with a particle size of 1–50 μm and 0%–5% D 50 = 1-3μm B powder and 10% D 50 Composed of ultrafine B4C powder with a particle size of ≤5μm.

[0011] This invention provides a method for preparing low-cost, high-calorific-value boron-aluminum-based composite fuel, employing an ultrasonic liquid-phase dispersion composite method, comprising the following steps:

[0012] Add B powder and B4C powder to an organic solvent at a material-to-liquid ratio of 1:(5-25), disperse ultrasonically while simultaneously stirring mechanically, and after mixing evenly, add Al powder, continue to disperse ultrasonically while simultaneously stirring mechanically, and after complete mixing evenly, separate the solid and liquid, vacuum dry, cool, and pass through a 30-100 mesh sieve to obtain boron-aluminum based composite fuel.

[0013] Preferably, the organic solvent is anhydrous ethanol, isopropanol, ethyl acetate, or petroleum ether.

[0014] Preferably, the ultrasonic frequency before adding aluminum powder is 20-40 kHz, the stirring speed is 150-500 rpm, and the treatment time is 15-60 min; the ultrasonic frequency after adding aluminum powder is 20-40 kHz, the stirring speed is 200-600 rpm, and the treatment time is 30-90 min.

[0015] Preferably, the solid-liquid separation method is vacuum filtration, centrifugation, or solvent evaporation. When using solvent evaporation, the evaporation temperature is set 0–10°C above the boiling point of the organic solvent, and mechanical stirring is performed simultaneously with evaporation.

[0016] Preferably, the vacuum drying temperature is 80–110°C and the drying time is 1–3 hours.

[0017] This invention provides another low-cost, high-calorific-value boron-aluminum-based composite fuel preparation method, employing a mechanical ball milling composite method with an organic solvent as the ball milling process control agent. On one hand, the solvent evaporation-cooling cycle reduces the ball milling environment temperature and powder particle activity, preventing hard agglomeration phenomena such as cold welding and clumping between particles; on the other hand, it creates a sealed environment between the powder particles, avoiding oxidative deactivation of the powder particles during ball milling. The method includes the following steps:

[0018] Al powder, B powder and B4C powder are mixed in proportion, and ceramic balls with Φ=1~6mm are used as the ball milling medium. Organic solvent is used as the process control agent. The Al / B / B4C mixed powder is ball milled and compounded under inert gas protection using a planetary ball mill. After ball milling, the organic solvent is removed by vacuum filtration, vacuum drying, cooling and passing through a 30~100 mesh sieve to obtain boron-aluminum based composite fuel.

[0019] Preferably, the ceramic spheres are Al2O3, ZrO2, or TiC.

[0020] Preferably, the organic solvent is anhydrous ethanol, n-hexane, or cyclohexane.

[0021] Preferably, the ball-to-material ratio is 3:1 to 9:1, the solid-liquid ratio is 1:1 to 1:3, the rotation speed is 100 to 600 rpm, and the ball milling time is 1 to 3 hours.

[0022] Preferably, the vacuum drying temperature is 80–110°C and the drying time is 1–3 hours.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1) This invention uses median diameter D 50 By partially or completely replacing amorphous boron powder with ultrafine B4C powder of ≤5μm, and by adjusting the ratio of aluminum powder, ultrafine B4C powder and boron powder, a boron-aluminum based composite powder with a measured calorific value >32.0kJ / g and a raw material cost <300 yuan / kg was obtained. The composition is simple and the main raw materials are inexpensive and readily available.

[0025] (2) The present invention uses ultrasonic liquid phase dispersion or mechanical ball milling technology to achieve uniform compounding of Al powder, B4C powder and B powder in a specific ratio. The preparation process is stable and reliable, the equipment investment is low, and it can achieve mass production. Attached Figure Description

[0026] Figure 1 The particle size distribution and SEM image of the ultrafine B4C powder are shown.

[0027] Figure 2The image shows a SEM image of the 85Al / 10B4C / 5B composite powder prepared in Example 1.

[0028] Figure 3 A route and cost analysis diagram for producing boron-containing products from existing boron-containing minerals. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0030] The raw materials or reagents used in the following examples can all be obtained by commercial purchase or by referring to existing methods.

[0031] Example 1

[0032] Weigh out 255.0g of spherical micronized Al powder (FLQT3) and 30.0g of ultrafine B4C powder (D). 50 =2.7±0.2μm) and 15.0g of high-purity amorphous boron powder (95B, D) 50 =1.3±0.1μm), B4C powder and B powder were added sequentially to 1.0L of anhydrous ethanol and ultrasonically dispersed at a frequency of 40kHz. During this process, the solvent was mechanically stirred simultaneously using a toothed impeller at a speed of 200rpm. After 30min, aluminum powder was slowly added, and then the impeller speed was adjusted to 300rpm for 60min of dispersion and composite treatment. After the composite treatment was completed, solid-liquid separation was performed using a vacuum filter. The resulting 85Al / 10B4C / 5B composite cake was placed in a vacuum drying oven and dried at 80℃ for 2.0h. After sufficient cooling, it was sieved through a 60-mesh sieve to obtain 85Al / 10B4C / 5B boron-aluminum based composite powder.

[0033] Figure 1 The particle size distribution and SEM image of the ultrafine B4C powder are shown. Figure 2 The SEM image of the 85Al / 10B4C / 5B composite powder prepared in Example 1 shows that the Al, B, and B4C particles in the composite powder are relatively uniformly combined. The morphology and particle size of the three particles have not changed and they remain in their original state. Only a few scratches are present on the surface of the spherical Al particles due to the collision of hard B and B4C particles. As shown in Table 1, the calorific value of the composite powder under pure oxygen environment of 3.0 MPa, measured by oxygen bomb calorimeter, is (32.91±0.34) kJ / g, which is 8.6% higher than the measured calorific value of FLQT3 Al powder under the same conditions (30.3±0.2) kJ / g. At the same time, based on the average market price of Al powder (50 yuan / kg), B powder (2500 yuan / kg), and B4C powder (75 yuan / kg), the raw material price of 85Al / 10B4C / 5B composite powder is 175 yuan / kg.

[0034] Table 1 Comparison of mass calorific value of composite powder in different embodiments

[0035]

[0036]

[0037] ★B4C powder and B powder are measured to be 99% and 95% pure, respectively.

[0038] Example 2

[0039] Weigh out 255.0g of spherical micronized Al powder (FLQT3) and 30.0g of ultrafine B4C powder (D). 50 =2.7±0.2μm) and 15.0g of high-purity amorphous boron powder (95B, D) 50 =1.3±0.1μm), using 1.5kg of Φ3mm zirconia balls as the ball milling medium and 1.0L of n-hexane as the process control agent, the ball milling compound was carried out at a speed of 200rpm for 1.5h under high-purity nitrogen protection. Then, solid-liquid separation was performed using a vacuum filter. The material containing the grinding balls was placed in a vacuum drying oven at 100℃ and dried for 2.0h. After cooling, it was sieved through a 60-mesh sieve to obtain 85Al / 10B4C / 5B boron-aluminum based composite powder.

[0040] As shown in Table 1, the calorific value of the composite powder under pure oxygen at 3.0 MPa is (33.42±0.17) kJ / g, which is 10.3% higher than that of FLQT3 Al powder and slightly higher than that of the same component composite powder prepared by ultrasonic composite method. This may be because mechanical ball milling composite better achieves uniform composite between Al, B4C and B particles.

[0041] Example 3

[0042] Weigh out 150.0g of spherical micronized Al powder (FLQT4) and 30.0g of ultrafine B4C powder (D). 50 =2.7±0.2μm) and 20.0g of high-purity amorphous boron powder (95B, D) 50 =1.3±0.1μm), B4C powder and B powder were added sequentially to 600mL of anhydrous ethanol and ultrasonically dispersed at a frequency of 40kHz. During this process, the solvent was mechanically stirred simultaneously using a toothed impeller at a speed of 200rpm. After 30min, FLQT4 aluminum powder was slowly added, and then the impeller speed was adjusted to 300rpm for 60min of dispersion and composite treatment. After the composite treatment was completed, solid-liquid separation was performed using a vacuum filter. The resulting 75Al / 15B4C / 10B composite cake was placed in a vacuum drying oven and dried at 80℃ for 2.0h. After sufficient cooling, it was sieved through a 60-mesh sieve to obtain 75Al / 20B4C / 10B boron-aluminum based composite powder.

[0043] As shown in Table 1, the calorific value of this composite powder under pure oxygen conditions of 3.0 MPa is (33.12 ± 0.27) kJ / g, which is 9.3% higher than that of FLQT3 Al powder. The raw material price of 75Al / 20B4C / 10B composite powder is 299 yuan / kg.

[0044] Example 4

[0045] Weigh out 180.0g of spherical micronized Al powder (FLQT4) and 20.0g of ultrafine B4C powder (D). 50 =2.7±0.2μm), B4C powder was added to 600mL of anhydrous ethanol and ultrasonically dispersed at 40kHz, while the solvent was mechanically stirred at 200rpm using a toothed impeller. After 30min, FLQT4 aluminum powder was slowly added, and the impeller speed was adjusted to 300rpm for 60min of dispersion and composite treatment. After the composite treatment, solid-liquid separation was performed using a vacuum filter. The resulting 90Al / 10B4C composite cake was placed in a vacuum drying oven and dried at 80℃ for 2.0h. After sufficient cooling, it was sieved through a 60-mesh sieve to obtain 90Al / 10B4C boron-aluminum based composite powder.

[0046] As shown in Table 1, the calorific value of the composite powder under pure oxygen conditions of 3.0 MPa is (32.10 ± 0.10) kJ / g, which is 5.9% higher than that of FLQT3 Al powder. The raw material price of 90Al / 10B4C composite powder is 52.5 yuan / kg.

[0047] Example 5

[0048] Weigh out 240.0g of spherical micronized Al powder (FLQT3) and 60.0g of ultrafine B4C powder (D). 50 =2.7±0.2μm), using 1.5kg of Φ3mm zirconia balls as the ball milling medium and 1.0L of n-hexane as the process control agent, the ball milling compound was carried out at a speed of 200rpm for 1.5h under the protection of high-purity nitrogen. Then, solid-liquid separation was carried out by vacuum filtration. The material containing the grinding balls was placed in a vacuum drying oven at 100℃ and dried for 2.0h. After cooling, it was sieved through a 60-mesh sieve to obtain 80Al / 20B4C boron-aluminum based composite powder.

[0049] As shown in Table 1, the calorific value of the composite powder under pure oxygen conditions of 3.0 MPa is (32.68 ± 0.23) kJ / g, which is 7.9% higher than that of FLQT3 Al powder. The raw material price of 80Al / 20B4C composite powder is 55 yuan / kg.

[0050] Comparative Example 1

[0051] Weigh out 210.0g of spherical micronized Al powder (FLQT3) and 60.0g of ultrafine B4C powder (D). 50 =2.7±0.2μm) and 30.0g of high-purity amorphous boron powder (95B, D) 50 =1.3±0.1μm), using 1.5kg of Φ3mm zirconia balls as the ball milling medium and 1.0L of n-hexane as the process control agent, the ball milling compound was carried out at a speed of 200rpm for 1.5h under the protection of high-purity nitrogen. Then, solid-liquid separation was carried out by vacuum filtration. The material containing the grinding balls was placed in a vacuum drying oven at 100℃ and dried for 2.0h. After cooling, it was sieved through a 60-mesh sieve to obtain 70Al / 20B4C / 10B boron-aluminum based composite powder.

[0052] As shown in Table 1, the calorific value of this composite powder under pure oxygen conditions of 3.0 MPa is (28.63 ± 0.62) kJ / g, which is 5.5% lower than that of FLQT3 Al powder. Furthermore, the raw material price of the 70Al / 20B4C / 10B composite powder is 300 yuan / kg.

Claims

1. A high-calorific-value boron-aluminum-based composite fuel, characterized in that, By weight percentage, it consists of 75%–90% Al powder with a particle size of 1–50 μm, 0%–10% D 50 = 1~3 μm B powder and 10%~20% D 50 Composed of ultrafine B4C powder with a particle size of ≤5 μm.

2. The high-calorific-value boron-aluminum-based composite fuel according to claim 1, characterized in that, Al powder is either spherical or flake-shaped.

3. The high-calorific-value boron-aluminum-based composite fuel according to claim 1, characterized in that, By weight percentage, it consists of 85%–90% Al powder with a particle size of 1–50 μm, 0%–5% D 50 = 1~3 μm B powder and 10% D 50 Composed of ultrafine B4C powder with a particle size of ≤5 μm.

4. The method for preparing high-calorific-value boron-aluminum-based composite fuel according to any one of claims 1 to 3, characterized in that, The ultrasonic liquid-phase dispersion and recombination method includes the following steps: Add B powder and B4C powder to an organic solvent at a material-to-liquid ratio of 1:(5~25), disperse ultrasonically while mechanically stirring, and mix evenly. Then add Al powder and continue to disperse ultrasonically while mechanically stirring. After mixing evenly, separate the solid and liquid, vacuum dry, cool, and pass through a 30~100 mesh sieve to obtain boron-aluminum based composite fuel.

5. The preparation method according to claim 4, characterized in that, The organic solvent is anhydrous ethanol, isopropanol, ethyl acetate or petroleum ether; the ultrasonic frequency before adding aluminum powder is 20~40 kHz, the stirring speed is 150~500 rpm, and the treatment time is 15~60 min; the ultrasonic frequency after adding aluminum powder is 20~40 kHz, the stirring speed is 200~600 rpm, and the treatment time is 30~90 min.

6. The preparation method according to claim 4, characterized in that, The solid-liquid separation method is vacuum filtration, centrifugation, or solvent evaporation; the vacuum drying temperature is 80~110 ℃, and the drying time is 1~3 h.

7. The preparation method according to claim 6, characterized in that, When using the solvent evaporation method, the evaporation temperature is set at 0-10 °C above the boiling point of the organic solvent, and mechanical stirring is performed during evaporation.

8. The method for preparing high-calorific-value boron-aluminum-based composite fuel according to any one of claims 1 to 3, characterized in that, The mechanical ball milling composite method includes the following steps: Al powder, B powder and B4C powder are mixed in proportion, and ceramic balls with Φ = 1~6 mm are used as the ball milling medium. Organic solvent is used as the process control agent. The Al / B / B4C mixed powder is ball milled and compounded under inert gas protection using a planetary ball mill. After ball milling, the organic solvent is removed by vacuum filtration, vacuum drying, cooling and passing through a 30~100 mesh sieve to obtain boron-aluminum based composite fuel.

9. The preparation method according to claim 8, characterized in that, The ceramic balls are made of Al2O3, ZrO2 or TiC, the organic solvent is anhydrous ethanol, n-hexane or cyclohexane, the ball-to-material ratio is 3:1 to 9:1, the solid-liquid ratio is 1:1 to 1:3, the rotation speed is 100 to 600 rpm, and the ball milling time is 1 to 3 h.

10. The preparation method according to claim 8, characterized in that, The vacuum drying temperature is 80~110 ℃, and the drying time is 1~3 h.

Images