Lithium fluoride deposited boron fuel and preparation method thereof

Abstract

The invention provides a lithium fluoride deposited boron fuel and a preparation method thereof, the method takes a boron fuel as a carrier, and the method adopts an acid-base neutralization reaction to deposit lithium fluoride particles on the surface of the boron fuel to prepare the lithium fluoride deposited boron fuel. The acid-base neutralization reaction takes lithium hydroxide and hydrofluoric acid as raw materials, and the lithium hydroxide and the hydrofluoric acid react to generate lithium fluoride particles. The reaction temperature of the acid-base neutralization reaction is room temperature, and the reaction time is 30 minutes. The loading capacity of the lithium fluoride particles is 1.0 wt% to 20.0 wt%. The particle size of the lithium fluoride particles is 1 nm to 10 nm. The temperature corresponding to an oxidation peak is 649-652 DEG C; and the ignition delay time is 49.8 to 41.3 ms. The LiF / B composite fuel prepared by the preparation method disclosed by the invention has a relatively low oxidation temperature. The LiF / B composite fuel prepared by the invention has relatively short ignition delay time.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-energy fuels and relates to boron fuel, in particular to a lithium fluoride deposited boron fuel and a preparation method thereof. Background Art

[0002] Boron powder (B) as a high energy fuel has a significant energy density advantage, its volume calorific value (1310MJ / m 3 ) and mass calorific value (58.3MJ / kg) are both at a high level, and the combustion products are environmentally friendly. Based on these characteristics, the green and environmentally friendly characteristics of boron-based propellants make it an important direction in the current propellant research field. However, there are several technical challenges in the practical application of boron: first, its high melting point (2076℃) and boiling point (3927℃) make it difficult to fully melt and vaporize it; second, the oxide layer (B2O3) formed on the surface during the combustion process has a low melting point (450℃), but its boiling point (1860℃) is still significantly higher than the conventional combustion environment temperature. In terms of combustion kinetics, the oxidation process of boron can be divided into two stages: the initial stage is the reaction of the surface B2O3 layer with O2 and H2O to produce intermediates such as BO2 and HOBO; the subsequent stage involves the internal clean surface reacting with O2 to form an O=BB=O structure. It is worth noting that the formation of HOBO will lead to a decrease in energy release efficiency, which is one of the key factors that cause the incomplete release of boron combustion heat. These combustion characteristics together result in boron having an ignition delay time and combustion duration significantly longer than those of volatile metals, and in a finite volume system, it can usually only release a small fraction of its theoretical calorific value. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a lithium fluoride deposited boron fuel and a preparation method thereof, so as to solve the technical problem in the prior art that the oxidation temperature and ignition delay time need to be further reduced.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A method for preparing lithium fluoride-deposited boron fuel uses the boron fuel as a carrier and deposits lithium fluoride particles on the surface of the boron fuel through acid-base neutralization reaction to prepare the lithium fluoride-deposited boron fuel.

[0006] The present invention also has the following technical features:

[0007] Specifically, the acid-base neutralization reaction uses lithium hydroxide (LiOH) and hydrofluoric acid (HF) as raw materials, and lithium hydroxide and hydrofluoric acid react to generate lithium fluoride (LiF) particles.

[0008] Preferably, the reaction temperature of the acid-base neutralization reaction is room temperature, and the reaction time is 30 minutes.

[0009] Specifically, the method includes the following steps:

[0010] Step 1: Pour the boron fuel into a container, add water, perform ultrasonication, and magnetic stirring;

[0011] Step 2: Weigh the amount of lithium hydroxide required at different loadings, then add water to dissolve it, and add the dissolved lithium hydroxide solution dropwise into the container in step 1 while stirring continuously.

[0012] Step 3: pipette the hydrofluoric acid solution dropwise into the container in step 2 while stirring continuously.

[0013] Step 4: collecting the product by centrifugation, washing the product with water, drying and grinding the washed product to obtain boron fuels with different loading amounts of lithium fluoride deposition.

[0014] Preferably, in step 2, when the loading amount of the lithium fluoride particles is 1.0wt%, the amount of lithium hydroxide required to be added is 16.34mg; when the loading amount of the lithium fluoride particles is 3.5wt%, the amount of lithium hydroxide required to be added is 58.67mg; when the loading amount of the lithium fluoride particles is 7.0wt%, the amount of lithium hydroxide required to be added is 121.76mg; when the loading amount of the lithium fluoride particles is 20.0wt%, the amount of lithium hydroxide required to be added is 404.4mg.

[0015] Preferably, in step three, when the loading amount of the lithium fluoride particles is 1.0wt%, the amount of hydrofluoric acid solution required to be added is 778.8uL; when the loading amount of the lithium fluoride particles is 3.5wt%, the amount of hydrofluoric acid solution required to be added is 2.7964mL; when the loading amount of the lithium fluoride particles is 7.0wt%, the amount of hydrofluoric acid solution required to be added is 5.8034mL; when the loading amount of the lithium fluoride particles is 20.0wt%, the amount of hydrofluoric acid solution required to be added is 19.2752mL.

[0016] More specifically, the method comprises the following steps:

[0017] Step 1: Weigh 1 g of boron fuel into a 150 ml plastic conical flask, add 60 ml of deionized water, sonicate for 10 min, and magnetically stir for 10 min;

[0018] Step 2: Use a small beaker to weigh the amount of lithium hydroxide required at different loadings, then add 5 ml of deionized water to dissolve it, and use a dropper to add the dissolved lithium hydroxide solution dropwise into the plastic conical flask in step 1, and continue magnetic stirring for 10 minutes.

[0019] Step 3: Use a pipette to transfer 0.5 mol / L hydrofluoric acid solution dropwise into the plastic conical flask prepared in step 2 and stir continuously for 30 minutes.

[0020] Step 4: Collect the product by centrifugation, wash the product with deionized water three times, dry and grind the washed product in an oven at 80° C. to obtain boron fuels with different loading amounts of lithium fluoride deposition.

[0021] The present invention also protects a lithium fluoride deposited boron fuel, which is prepared by the above-mentioned preparation method of the lithium fluoride deposited boron fuel.

[0022] The loading amount of the lithium fluoride particles is 1.0 wt% to 20.0 wt%.

[0023] The particle size of the lithium fluoride particles is 1 nm to 10 nm.

[0024] The temperature corresponding to the oxidation peak of the boron fuel deposited with lithium fluoride is 649-652° C.; the ignition delay time of the boron fuel deposited with lithium fluoride is 49.8-41.3 ms.

[0025] Compared with the prior art, the present invention has the following technical effects:

[0026] (I) In the present invention, the role of LiF is to promote the combustion of the boron fuel, significantly shorten the ignition delay time of the boron fuel and reduce the combustion temperature, while also reducing the processing difficulty of the boron fuel.

[0027] (II) The LiF / B composite fuel prepared by the present invention has a lower oxidation temperature; the LiF / B composite fuel prepared by the present invention has a shorter ignition delay time.

[0028] (III) The preparation method of the present invention is simple, efficient, reproducible and low-cost.

[0029] (IV) The preparation method adopted by the present invention has high control precision, is easy to industrialize, and shows good application prospects in the field of high-energy solid fuel modification. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the SEM image of boron fuel without any modification.

[0031] Figure 2 SEM and element distribution images of 3.5wt% LiF / B composite fuel.

[0032] Figure 3 XPS Li 1s, F 1s, B 1s and O 1s spectra of 3.5 wt% LiF / B composite fuel.

[0033] Figure 4 XRD data of LiF / B composite fuel: a0 is boron fuel without any modification, a1 is 1.0wt%-LiF / B, and a2 is 7.0wt%-LiF / B.

[0034] Figure 5 DSC data of LiF / B composite fuel: a0 is B element, a1 is 3.5wt%-LiF / B, and a2 is 7.0wt%-LiF / B.

[0035] Figure 6 TG data of LiF / B composite fuel: a0 is B element, a1 is 3.5wt%-LiF / B, and a2 is 7.0wt%-LiF / B.

[0036] Figure 7 This is the laser ignition delay time data of LiF / B composite fuel.

[0037] The specific contents of the present invention are further explained in detail below with reference to the embodiments. DETAILED DESCRIPTION

[0038] It should be noted that, unless otherwise specified, all materials and equipment in the present invention are those known in the art.

[0039] In the present invention, boron fuel refers to boron powder, which can also be referred to as boron particles or elemental boron; all four are synonymous. The boron fuel can be amorphous and / or crystalline, with a particle size distribution ranging from micrometers to nanometers. Preferably, the particle size of the boron fuel is 100 nm to 5 μm.

[0040] In the present invention, LiF / B composite fuel refers to boron fuel deposited with lithium fluoride.

[0041] In the present invention, the reaction formula of the acid-base neutralization reaction is: LiOH+HF→LiF+H2O.

[0042] The present invention introduces a fluoride additive as an effective technical solution to optimize the processing performance of boron powder and improve its combustion characteristics, while also increasing the loading rate of boron powder and ultrafine oxidizer in the propellant system. The addition of fluoride has the following effects: (1) reducing the processing difficulty of boron fuel; (2) improving ignition performance; and (3) promoting combustion efficiency. The method of the present invention provides a new research direction for propellant performance optimization.

[0043] The boron fuel deposited by lithium fluoride of the present invention is used as a boron-based fuel in the field of explosives.

[0044] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0045] Example:

[0046] This embodiment provides a method for preparing a boron fuel deposited with lithium fluoride, the method comprising the following steps:

[0047] Step 1: Perform the experiment in a fume hood. Weigh 1 g of boron fuel into a 150 ml plastic conical flask, add 60 ml of deionized water, sonicate for 10 min, and magnetically stir for 10 min.

[0048] Step 2: Use a small beaker to weigh the amount of lithium hydroxide required at different loadings, then add 5 ml of deionized water to dissolve it, and use a dropper to add the dissolved lithium hydroxide solution dropwise into the plastic conical flask in step 1, and continue magnetic stirring for 10 minutes.

[0049] Step 3: Use a pipette to transfer 0.5 mol / L hydrofluoric acid solution dropwise into the plastic conical flask prepared in step 2 and stir continuously for 30 minutes.

[0050] Step 4: Collect the product by centrifugation, wash the product three times with deionized water, dry and grind the washed product in an oven at 80°C to obtain LiF / B composite fuels with loading amounts of 1.0wt%, 3.5wt%, 7.0wt% and 20.0wt%, i.e., boron fuel deposited with lithium fluoride.

[0051] Structural characterization of LiF / B composite fuel:

[0052] Figure 1 This is the SEM picture of the B element. Through the scanning electron microscope, it can be seen that the B fuel without LiF deposition has a regular morphology and a stacked block structure.

[0053] Figure 2 The SEM and element distribution images of 3.5wt% LiF / B composite fuel. Figure 1 There is basically no difference, that is, the deposition of LiF does not change the morphology of the carrier B fuel. In addition, the element distribution image shows that the distribution diagrams of B, Li, and F are almost the same, which indicates that LiF is evenly distributed on the B fuel. Figure 2 It can also be seen that in the 3.5 wt% LiF / B composite fuel, the particle size of the LiF particles is 1 nm to 10 nm.

[0054] Figure 3XPS Li 1s, F 1s, B 1s and O 1s spectra of 3.5wt% LiF / B composite fuel. In the B1s spectrum, 187.5eV is attributed to B 0 The peak at 192.5 eV is attributed to B 3+ During the LiF deposition experiment, part of the surface B was oxidized to B2O3. The peak of 55.8eV in the Li 1s spectrum is attributed to Li + The peak of F 1s spectrum is assigned to F - It can be seen from the peak that the product generated by the acid-base neutralization is LiF species.

[0055] Figure 4 XRD data for LiF / B composite fuel: a0 represents unmodified boron fuel, a1 represents 1.0 wt% LiF / B, and a2 represents 7.0 wt% LiF / B. This indicates that the loading of LiF onto the boron fuel via acid-base neutralization does not alter the boron's crystalline structure, and the deposited LiF is highly dispersed.

[0056] TG-DSC test of LiF / B composite fuel:

[0057] Weigh the LiF / B composite fuel into an alumina crucible and place the crucible on the sample stage of the TG-DSC instrument. Enter the sample mass and set the instrument's heating rate to 10K / min. The test temperature range is room temperature to 900°C, and the test atmosphere is air. In this way, the TG and DSC curves of the LiF / B composite fuel can be obtained.

[0058] Figure 5 DSC data for LiF / B composite fuel: where a0 represents elemental B, a1 represents 3.5 wt% LiF / B, and a2 represents 7.0 wt% LiF / B. The oxidation peaks for elemental B, 3.5 wt% LiF / B, and 7.0 wt% LiF / B correspond to temperatures of 677°C, 652°C, and 649°C, respectively. LiF deposition advances the oxidation temperature of fuel B, which then decreases gradually with increasing LiF loading.

[0059] Figure 6 The TG data of LiF / B composite fuel: a0 is B element, a1 is 3.5wt%-LiF / B, and a2 is 7.0wt%-LiF / B. Figure 5 The DSC results are consistent with those in .

[0060] Laser ignition delay time test of LiF / B composite fuel:

[0061] LiF / B composite fuel was weighed into an alumina crucible, which was placed on the sample stage of a laser ignition instrument. The instrument parameters were set as follows: frequency Hz: 1000; duty cycle (1-40%): 3; number of pulses: 1000; pulse train output; power: 40 W; pulse energy: 40 mJ; and pulse width: 30 μs.

[0062] Figure 7 The laser ignition delay time data of LiF / B composite fuel is shown in the figure. The ignition delay time of unmodified B fuel is 63.8ms, the ignition delay time of 1.0wt%-LiF / B is 41.3ms, the ignition delay time of 3.5wt%-LiF / B is 49.8ms, and the ignition delay time of 7.0wt%-LiF / B is 45.8ms.

[0063] The ignition delay time of 20.0wt%-LiF / B is 48.8ms. The ignition delay time of the LiF / B composite fuel prepared by the present invention is significantly shorter than that of the B fuel without LiF deposition, and the ignition delay time of LiF / B is not greatly affected by the amount of LiF deposition.

[0064] Compared with existing technologies, the LiF / B composite fuel prepared in the present invention has advantages such as good reproducibility and easy ignition. The preparation process of this type of LiF / B composite fuel is simple and convenient. The acid-base neutralization reaction technology employed in this experimental method uses mild conditions, and the experimental chemicals are all common laboratory chemicals. The sample preparation cost is low. The LiF / B composite fuel of the present invention is easy to prepare, has good reproducibility, and is inexpensive, significantly reducing the preparation cost of boron-based fuels and showing promising application prospects.

Claims

1. A method for preparing boron fuel deposited with lithium fluoride, wherein the method uses boron fuel as a carrier, characterized in that: The method uses acid-base neutralization reaction to deposit lithium fluoride particles on the surface of boron fuel to prepare boron fuel with lithium fluoride deposition.

2. The method for preparing the boron fuel deposited by lithium fluoride according to claim 1, wherein: The acid-base neutralization reaction uses lithium hydroxide and hydrofluoric acid as raw materials, and lithium hydroxide and hydrofluoric acid react to generate lithium fluoride particles.

3. The method for preparing the boron fuel deposited by lithium fluoride according to claim 2, wherein: The reaction temperature of the acid-base neutralization reaction is room temperature, and the reaction time is 30 minutes.

4. The method for preparing the boron fuel deposited by lithium fluoride according to claim 1, wherein: The method comprises the following steps: Step 1: Pour the boron fuel into a container, add water, perform ultrasonication, and magnetic stirring; Step 2: Weigh the amount of lithium hydroxide required at different loadings, add water to dissolve it, and add the dissolved lithium hydroxide solution dropwise into the container in step 1 while stirring continuously; Step 3: pipette the hydrofluoric acid solution dropwise into the container in step 2 while stirring continuously; Step 4: collecting the product by centrifugation, washing the product with water, drying and grinding the washed product to obtain boron fuels with different loading amounts of lithium fluoride deposition.

5. The method for preparing boron fuel deposited with lithium fluoride according to claim 4, wherein: In step 2, when the loading amount of the lithium fluoride particles is 1.0wt%, the amount of lithium hydroxide required to be added is 16.34mg; when the loading amount of the lithium fluoride particles is 3.5wt%, the amount of lithium hydroxide required to be added is 58.67mg; when the loading amount of the lithium fluoride particles is 7.0wt%, the amount of lithium hydroxide required to be added is 121.76mg; when the loading amount of the lithium fluoride particles is 20.0wt%, the amount of lithium hydroxide required to be added is 404.4mg.

6. The method for preparing boron fuel deposited by lithium fluoride according to claim 4, characterized in that: In step three, when the loading amount of the lithium fluoride particles is 1.0wt%, the amount of hydrofluoric acid solution required to be added is 778.8uL; when the loading amount of the lithium fluoride particles is 3.5wt%, the amount of hydrofluoric acid solution required to be added is 2.7964mL; when the loading amount of the lithium fluoride particles is 7.0wt%, the amount of hydrofluoric acid solution required to be added is 5.8034mL; when the loading amount of the lithium fluoride particles is 20.0wt%, the amount of hydrofluoric acid solution required to be added is 19.2752mL.

7. The method for preparing boron fuel deposited with lithium fluoride according to claim 4, wherein: The method comprises the following steps: Step 1: Weigh 1 g of boron fuel into a 150 ml plastic conical flask, add 60 ml of deionized water, sonicate for 10 min, and magnetically stir for 10 min; Step 2: Use a small beaker to weigh the amount of lithium hydroxide required at different loadings, then add 5 ml of deionized water to dissolve it, and use a dropper to add the dissolved lithium hydroxide solution dropwise to the plastic conical flask in step 1, and continue magnetic stirring for 10 minutes; Step 3: Use a pipette to pipette 0.5 mol / L hydrofluoric acid solution and add it dropwise to the plastic conical flask prepared in step 2 and stir continuously for 30 min. Step 4: Collect the product by centrifugation, wash the product with deionized water three times, dry and grind the washed product in an oven at 80° C. to obtain boron fuels with different loading amounts of lithium fluoride deposition.

8. A boron fuel deposited with lithium fluoride, characterized in that: The boron fuel is prepared by the method for preparing the boron fuel by lithium fluoride deposition as claimed in any one of claims 1 to 7; The loading amount of the lithium fluoride particles is 1.0 wt% to 20.0 wt%.

9. The lithium fluoride deposited boron fuel according to claim 8, wherein The particle size of the lithium fluoride particles is 1 nm to 10 nm.

10. The lithium fluoride deposited boron fuel according to claim 8, wherein The temperature corresponding to the oxidation peak of the boron fuel deposited with lithium fluoride is 649-652° C.; the ignition delay time of the boron fuel deposited with lithium fluoride is 49.8-41.3 ms.

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