Aluminum-doped boron-based aluminothermic energetic devices

Abstract

The application relates to an aluminum-doped boron-aluminum thermic energetic device, and a preparation method thereof. The preparation method comprises the following steps: preparing boron oxide powder with controllable specific surface area by selecting a boron salt composition and obtaining a suitable pretreated precursor, and then adopting a sectional heat treatment forming method; pressing the film into a required thin film; and then using vacuum controllable metal aluminum evaporation and spray modification to realize the compounding of the nano aluminum film and the controllable doping of fluorine, so that a new fluorine-doped aluminum-boron-aluminum thermic energetic device with excellent performance is prepared.

Description

Technical Field

[0001] This invention relates to an aluminothermic energetic device and its preparation. Background Technology

[0002] Energetic devices are considered to be energy devices that rapidly release heat energy under certain external energy stimulation, and they have been widely used in military, weaponry, pyrotechnics, sensors and other fields.

[0003] It is worth mentioning that nano-aluminum-based energetic devices have become a key focus in this field due to their advantages such as fast combustion rate and high energy. The oxidants mainly include polymers, copper oxide, iron oxide, bismuth oxide, cobalt oxide, nickel oxide, and molybdenum oxide. For example, RQ Shen designed a novel hydrophobic Al / polyvinylidene@azidopolymer / nitrocellulose energetic device with a core-shell structure, exhibiting excellent hydrophobic properties and enhanced reactivity (Chem.Eng.J.2022,427,132001), and a low-wetting Al / CuO energetic device (Chem.Eng.J.2023,473,145031), using modified coaxial electrospinning and 3D direct writing techniques, respectively, and explored their effective combustion and explosion performance at the air / water interface and related mechanisms. Summary of the Invention

[0004] The purpose of this invention is to provide a nano-aluminum-based energetic device with a superior structure, stronger energy release, and greater stability.

[0005] According to a first aspect of the present invention, a method for fabricating a fluorine-doped aluminum-based boron alumina thermally energetic device is provided, comprising:

[0006] A mixture of boron salt and boric acid is provided, wherein the mass ratio of boron salt to boric acid is (10-20):1;

[0007] The composition is preheated in a vacuum microwave environment to form a precursor, wherein the vacuum level is (1.0–5.0) × 10⁻⁶. -3 Pa, processing time is 0.1 to 1 hour, temperature is 50 to 70℃;

[0008] The preheated precursor was subjected to segmented controlled calcination to obtain boron oxide fractions. The temperature range was controlled at 300–500℃, with gradient temperature increases of 10–50℃, each gradient temperature control time of 10–30 min, and the calcination pressure of (0.8–1.2) × 10⁻⁶. 5 Pa;

[0009] The obtained boron oxide powder was mixed with a binder and then pressed into a boron oxide film.

[0010] Aluminum-based boron oxide aluminothermic composite energetic device is formed by vacuum evaporation of metallic aluminum onto a boron oxide thin film, wherein the vacuum degree is (1.0~5.0)×10 -3 Pa, temperature 30-60℃, evaporation current 100-300mA, time 0.1-1h;

[0011] A modified solution is provided, consisting of heptadecafluorodecyltrimethoxysilane, dimethylphenylfluorosilane and ethanol, wherein the volume ratio of heptadecafluorodecyltrimethoxysilane, dimethylphenylfluorosilane and ethanol is (1-2):(1-2):(50-100);

[0012] Fluorine-doped aluminum-based boron oxide aluminothermic composite energetic device was obtained by spraying and drying the device with a modified solution.

[0013] According to the preparation method of the present invention, it is also preferable to further include vacuum cooling the boron oxide powder obtained after calcination to room temperature before pressing it into a film.

[0014] According to the preparation method of the present invention, although boron salts such as boron carbonate, boron sulfate, boron nitrate, and boron acetate can be used, boron carbonate is preferred, and its mass ratio with boric acid is (10-15):1.

[0015] According to the preparation method of the present invention, preferably during the spray treatment, the vertical distance between the spray nozzle and the surface of the aluminum-based boron aluminothermic composite energetic device is 1-5 cm, the spray temperature is 70-100°C, the spray time is 0.1-1 h, and the spray rate is 1-3 mL / min. More preferably, the spray time is 0.3-0.5 h, and the drying treatment after spraying is carried out under vacuum at a temperature of 70-90°C.

[0016] According to the preparation method of the present invention, the preferred gradient temperature rise interval during segmented controllable calcination is 15-25°C, and the temperature control time for each gradient is 10-20 min.

[0017] According to the preparation method of the present invention, any suitable binder can be used, as long as the amount is sufficient to bind the boron oxide powder together and press it into a film.

[0018] According to the preparation method of the present invention, the shape and size of the pressed boron oxide film are not limited. Depending on the actual use, the shape can be any of the following: square, rectangle, circle, triangle, pentagram, ring, polygon, trapezoid, etc., and the thickness can be adapted from several to several hundred millimeters. Therefore, the prepared fluorine-doped aluminum-based boron oxide aluminum thermally active device can be designed in different shapes to match different devices, thus facilitating portability and application.

[0019] According to a second aspect of the present invention, a fluorine-doped aluminum-based boron alumina thermally active device is also provided, which is prepared by the above method.

[0020] This invention first selects a boron salt composition and obtains a suitable pretreated precursor, then prepares boron oxide powder with controllable specific surface area using a segmented heat treatment molding method, and then presses it into the desired thin film. Next, it uses vacuum controllable evaporation of metallic aluminum and combined spray modification to realize the composite of nano-aluminum film and controllable fluorine doping, thereby obtaining a novel fluorine-doped aluminum-based boron oxide aluminum thermal energy device with excellent performance.

[0021] In summary, the present invention has at least the following advantages:

[0022] (1) The fluorine-doped aluminum-based boron oxide aluminum thermal energy devices prepared by this invention have diverse structures and are flexible and adjustable;

[0023] (2) The fluorine-doped aluminum-based boron oxide aluminothermic energy device prepared by the present invention has strong heat release capability, high heat release core temperature and strong energy release stability.

[0024] (3) The process of this invention is simple and convenient, and the operation is easy;

[0025] (4) The present invention achieves full contact in fluorine-doped aluminum-based boron oxide aluminum thermal energy-containing devices, and the introduction of fluorine significantly improves their exothermic lifetime.

[0026] (5) It has low requirements for raw materials and equipment, low design cost, and is suitable for large-scale production, with obvious advantages in industrial applications. Attached Figure Description

[0027] Figure 1 Various feasible structural shapes of the fluorine-doped aluminum-based boron alumina thermally energetic device according to the present invention are shown;

[0028] Figure 2 The hydrophobic properties of the sample device according to an embodiment of the present invention and the sample device of Comparative Example 1 are shown.

[0029] Figure 3 The graph shows the change in heat release of the sample device according to an embodiment of the present invention and the sample device of Comparative Example 1 during a 1-year aging test.

[0030] Figure 4 The graph shows the temperature change of the exothermic core of the sample device according to an embodiment of the present invention and the sample device of Comparative Example 1 during a 1-year aging test.

[0031] Figure 5 The diagram shows the heat release and heat release core temperature variation of the sample device according to an embodiment of the present invention and each comparative sample device. Detailed Implementation

[0032] The present invention is further illustrated below by way of examples. Those skilled in the art should understand that the following examples are only for better understanding and implementation of the present invention and are not intended to limit the present invention.

[0033] Example

[0034] First, weigh a mixture of boron carbonate and boric acid in a mass ratio of 12:1, evenly disperse it on a petri dish, and place it in a vacuum microwave heating device for microwave preheating treatment: set the vacuum degree to 3.03 × 10⁻⁶. -3 Pa, processing time 0.5h, temperature 60℃.

[0035] The precursor formed after microwave preheating was then transferred to a calcining furnace for segmented calcination: the calcination temperature increased from 320°C to 460°C, with a gradient (heating interval) of 20°C, each gradient temperature control time being 15 min, and the calcination pressure being maintained at 1.01 × 10⁻⁶. 5 Pa. After calcination, the mixture was vacuum cooled to 25°C to obtain boron oxide powder.

[0036] Then, the obtained boron oxide powder was mixed and stirred with a binder (the mass ratio of boron oxide powder to binder was 40:1), and then transferred to a square pressing device. The mixture was then heated to 3.03 × 10⁻⁶ mm. 5 A porous boron oxide film is formed by pressing the film under pressure for 0.2 hours. Of course, the porous boron oxide film can also be formed into any other suitable shape, for example... Figure 1 Various shapes are shown. Any suitable type of adhesive can be used; in this embodiment, it is formed using tackifying resin T-105, crosslinkable grafted acrylic pressure-sensitive adhesive SA5398, and ethanol in a volume ratio of 1:1:10.

[0037] Next, high-purity aluminum sheets (99.99%) were repeatedly cleaned and dried using alkaline washing, alcohol washing, and water washing, and then used as the raw material for aluminum evaporation deposition. The aluminum was then vacuum-deposited onto the aforementioned porous boron oxide film at a vacuum degree of 3.03 × 10⁻⁶. -3 Pa, vacuum evaporation temperature controlled at 45℃. Aluminum-based boron oxide aluminothermic composite energetic device was obtained by adjusting the evaporation current to 200mA and the evaporation time to 0.5h.

[0038] Prepare a mixed modified solution: heptadecyltrimethoxysilane, dimethylphenylfluorosilane and ethanol in a volume ratio of 1:1:50.

[0039] The prepared mixed modified liquid was transferred to a spraying device and sprayed onto the aluminum-based boron alumina thermally energetic device obtained above: the vertical distance between the spray nozzle and the device surface was 2 cm, the spraying temperature was 80℃, the spraying time was 0.4 h, and the spraying speed was controlled at 2 mL / min.

[0040] After spraying, the sample was transferred to a vacuum drying oven for drying: the temperature was controlled at 80℃, and the treatment time was 0.2h. Finally, after natural cooling, the fluorine-doped aluminum-based boron oxide aluminothermal energy-containing device of the present invention was obtained.

[0041] Comparative Example 1

[0042] The process is the same as in Example 1, except that the modified mixture is replaced with a base solution containing only ethanol, and heptadecafluorodecyltrimethoxysilane and dimethylphenylfluorosilane are not added. This yields an undoped aluminum-based boron alumina thermally active device.

[0043] Comparative Example 2

[0044] The rest is the same as in Example 1, except that boron carbonate in the microwave preheating step is replaced with boron acetate.

[0045] Comparative Example 3

[0046] The rest is the same as in Example 1, except that microwave preheating was not performed.

[0047] Comparative Example 4

[0048] The procedure is the same as in Example 1, except that the temperature gradient in the segmented calcination process is adjusted to 50°C and the temperature control time is increased to 30 min, while other conditions remain unchanged.

[0049] Comparative Example 5

[0050] The process is the same as in Example 1, except that the evaporation current is doubled (400mA) during the vacuum evaporation of aluminum.

[0051] Comparative Example 6

[0052] The rest is the same as in Example 1, except that the spraying time in the spray treatment is halved.

[0053] Performance testing and analysis

[0054] The specific surface area of ​​the samples in the examples and comparative examples was tested using the Brunauer-Emmett-Teller surface test method (BET), and the results are shown in Table 1 below.

[0055] Table 1

[0056]

[0057] The hydrophobicity of the samples in Example 1 and Comparative Example 1 as a function of aging time was measured using a contact angle meter. The test results are as follows: Figure 2 As shown, the hydrophobicity of the fluorine-doped aluminum-based boron alumina thermally active device (Example Sample) contrasts sharply with that of the undoped fluorine-doped aluminum-based boron alumina thermally active device (Comparative Example 1 Sample). The contact angle measured for the Comparative Example 1 sample is almost 0 degrees, indicating that this sample has no hydrophobic properties or extremely strong wettability, making it extremely prone to deliquescence. Consequently, its exothermic performance is easily degraded, as further illustrated below.

[0058] Differential scanning calorimetry (DSC) was used to measure the heat release and exothermic core temperature of the samples in Example 1 and Comparative Example 1 over aging time, respectively. The test results are as follows: Figure 3 and Figure 4 As shown in Table 1 and... Figure 3 and 4 As shown, the specific surface area, heat release capacity, and heat release core temperature of the fresh Comparative Example 1 sample are basically the same as those of the Sample of Example 1. However, after one year of natural aging test, the heat release capacity of the fluorine-doped aluminum-based boron oxide aluminothermic energy-containing device Sample of Example 1 remains at 97% of its initial value, and the heat release core temperature also remains at 95% of its initial value; while for the undoped Comparative Example 1 sample, the heat release capacity and heat release core temperature are only 2% and 1% of their initial values, respectively.

[0059] As shown in Table 1, the specific surface area of ​​the fluorine-doped aluminum-based boron oxide aluminum thermally active device sample in Comparative Example 2 is 201.12 cm². 2 / mg, approximately 90% of the sample in the examples. The analysis suggests that the difference in device porosity due to different preparation processes significantly reduces the effective contact area between the corresponding reactants, thereby hindering energy release.

[0060] Figure 5 This graph shows the changes in heat release and core temperature of the energetic devices in the embodiment (horizontal axis number 1) and comparative examples 1-6 (horizontal axis numbers 2-7). Figure 5 It can be seen that the heat release and heat release core temperature of the Comparative Example 2 sample are both 85±2% of those of the Example sample.

[0061] Table 1 and Figure 5The comparison between the example samples and other comparative samples is further shown. The specific surface area of ​​the fluorine-doped aluminum-based boron oxide aluminothermic thermally active device sample of Comparative Example 3 decreased by 25±2%; the corresponding heat release capacity and heat release core temperature decreased by 23±2% and 17±2%, respectively. The specific surface area of ​​the fluorine-doped aluminum-based boron oxide aluminothermic thermally active device sample of Comparative Example 4 decreased by 11±2%; the corresponding heat release capacity and heat release core temperature were both affected to varying degrees, decreasing by approximately 9±2% and 7±2%, respectively. The specific surface area of ​​the fluorine-doped aluminum-based boron oxide aluminothermic thermally active device sample of Comparative Example 5 decreased by 14±2%; this is likely due to the excess aluminum inhibiting the energy release process of the active device. The heat release and heat release core temperature of the sample of Comparative Example 5 were approximately 85±2% of those of the example samples. The specific surface area of ​​the fluorine-doped aluminum-based boron alumina thermally active device sample in Comparative Example 6 did not change much compared to the sample in the Example. This is likely due to the reduced spraying time, which led to a decrease in the hydrophobicity of the sample in Comparative Example 6, with a corresponding contact angle of approximately 145°, a decrease of 21° compared to the sample in the Example. Its heat release and heat release core temperature remained basically unchanged, approximately 98% and 97% of those of the sample in the Example, respectively. However, after one year of aging tests, it was found that the stability of its heat release and heat release core temperature both showed a significant decline, with declines of approximately 45% and 52%, respectively.

[0062] In summary, this invention has successfully fabricated a novel fluorine-doped aluminum-based boron oxide aluminothermic energy-containing device with outstanding performance.

Claims

1. A method for fabricating a fluorine-doped aluminum-based boron alumina thermally energetic device, comprising: A mixture of boron salt and boric acid is provided, wherein the mass ratio of boron salt to boric acid is (10~20):1; The mixture is preheated in a vacuum microwave environment to form a precursor, wherein the vacuum level is 1.0~5.0×10⁻⁶. -3 Pa, processing time is 0.1~1h, temperature is 50~70℃; The preheated precursor was subjected to segmented controlled calcination to obtain boron oxide powder. The temperature range was controlled at 300–500 °C, with a gradient temperature increase interval of 10–50 °C, and each gradient temperature control time was 10–30 min. The calcination pressure was 0.8–1.2 × 10⁻⁶. 5 Pa; The obtained boron oxide powder was mixed with a binder and then pressed into a boron oxide film. Aluminum-based boron oxide aluminothermic composite energetic device is formed by vacuum evaporation of metallic aluminum onto a boron oxide thin film, wherein the vacuum degree is 1.0~5.0×10⁻⁶. -3 Pa, temperature 30~60℃, evaporation current 100~300mA, time 0.1~1h; A modified solution is provided, consisting of heptadecafluorodecyltrimethoxysilane, dimethylphenylfluorosilane and ethanol, wherein the volume ratio of heptadecafluorodecyltrimethoxysilane, dimethylphenylfluorosilane and ethanol is (1~2):(1~2):(50~100). Fluorine-doped aluminum-based boron oxide aluminothermic composite energetic device was obtained by spraying and drying the device with a modified solution.

2. The preparation method according to claim 1 further includes vacuum cooling the boron oxide powder obtained after calcination to room temperature before pressing it into a film.

3. The preparation method according to claim 1, wherein the boron salt is boron carbonate, and its mass ratio with boric acid is (10~15):

1.

4. The preparation method according to claim 1, wherein during the spray treatment, the vertical distance between the spray nozzle and the surface of the aluminum-based boron aluminothermic composite energetic device is 1~5cm, the spray temperature is 70~100℃, the spray time is 0.1~1h, and the spray speed is 1~3mL / min.

5. The preparation method according to claim 4, wherein the spraying time is 0.3~0.5h, and the drying treatment after spraying is carried out under vacuum at a temperature of 70~90℃.

6. The preparation method according to claim 1, wherein the gradient heating interval during segmented controllable calcination is 15~25℃, and the temperature control time for each gradient is 10~20min.

7. A fluorine-doped aluminum-based boron alumina thermally active device, prepared by the method according to any one of claims 1-6.

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