Preparation method of CL-20 / B / Al / PTFE composite energetic material

Abstract

The invention discloses a preparation method of a CL-20 / B / Al / PTFE (Polytetrafluoroethylene) energetic material. According to the method, an emulsifier is used for enhancing interaction between interfaces of deionized water and dichloromethane, CL-20, B, Al and PTFE are limited in an oil-in-water structure formed by emulsification, TPU is separated out from dichloromethane, and various particles in the oil-in-water structure are self-assembled into an energy-containing micro-unit with CL-20 as a core material and B, Al and PTFE as a shell layer. The invention provides a process method for preparing the composite energetic material, the CL-20 / B / Al / PTFE energetic material with regular morphology is prepared by adopting an emulsion suspension volatilization process, and the main explosive in the structure is tightly combined with the metal fuel and the oxidant, so that the contact surface area among various materials is increased, the contact distance is shortened, the morphology of the composite particles is regular, and the preparation process is simple. The safety of the mixed explosive is expected to be improved. Compared with a composite energetic material prepared by a traditional physical mixing method and a direct method, the CL-20 / B / Al / PTFE composite energetic material prepared by the invention has better safety and combustion performance.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of energetic materials, and relates to a preparation process of a composite energetic material of CL-20 / Al / B / PTFE, aiming to improve the safety and combustion performance of the composite energetic material. Background Art

[0002] Hexanitrohexaazaisowurtzitane (CL-20) is one of the highest-energy single-component explosives applied so far, with higher energy and density compared to octogen (HMX). As the most attractive high-energy density compound at present, CL-20 has broad application prospects in the fields of propellants, composite explosives, propellants, etc.

[0003] The use of active metals in energetic materials can quickly and effectively improve their work capacity and explosive power. In the past, the most studied was aluminum powder. Research shows that the energy level of metallized explosives mainly depends on the calorific value of the active metal fuel additive. From a thermodynamic perspective, boron powder has greater thermodynamic potential than aluminum powder, and its theoretical volume calorific value and mass calorific value are 1.66 times and 1.9 times that of aluminum powder respectively. Boron powder has a higher combustion temperature. The energy released by the oxidation of aluminum powder can improve the oxidation efficiency of boron powder, enabling the combustion of aluminum powder to drive the combustion of boron and aluminum, thereby increasing the total energy release of the detonation reaction.

[0004] At present, many studies have shown that adding fluorine-containing materials to metal powders can react with metal powders such as aluminum and boron and their surface oxide layers. The fluorides produced by the reaction are usually more volatile than the corresponding oxides of the metal powders, thus avoiding or reducing ignition delay and combustion difficulties caused by the generation of metal oxides to improve the combustion performance of the metal powders. Therefore, PTFE with a higher fluorine content is selected and added to the composite energetic material system to improve the combustion efficiency of the metal powders in the system.

[0005] When preparing CL-20 composite explosives by traditional physical mixing methods and direct methods, they have great limitations themselves, and due to the influence of impact, friction, static electricity, etc. during the operation process, it is very likely to cause the explosion of the explosives, posing a great potential safety hazard. Therefore, an emulsion-suspension volatilization process is used to prepare a composite energetic material of CL-20, B, Al, and PTFE. The water phase and the oil phase are mixed together and emulsified by high-speed stirring to form an oil-in-water structure. The binder in the system is precipitated by slow stirring and volatilization, and an energetic material of CL-20 / Al / B / PTFE with uniform component distribution and regular structure is obtained. Summary of the Invention

[0006] The object of the present invention is to provide a preparation method of a CL-20 / B / Al / PTFE composite energetic material. The core content of the present invention is to use an emulsion-suspension volatilization process to compound CL-20, B, Al and PTFE to prepare a composite energetic material with regular morphology, good safety and combustion performance.

[0007] To achieve the above object, the steps for the preparation of the CL-20 / B / Al / PTFE energetic material are as follows.

[0008] Step 1, preparation of the oil phase:

[0009] Add a small amount of TPU to the organic solution, and stir well for 1-2 h to ensure that it is fully dissolved in the solvent. Add a certain amount of CL-20, B, Al and PTFE to the organic solvent, ultrasonicate for 0.5-1 h, and then stir magnetically for 1-2 h. A uniform suspension is formed to make the oil phase;

[0010] Step 2, preparation of the water phase:

[0011] Add PVA and Tween-80 to deionized water, heat in a water bath to 80-100 °C, and stir magnetically for 1-2 h to make an aqueous solution of the water phase. Pour it into a reagent bottle and let it stand and cool before use.

[0012] Step 3, preparation of the emulsion

[0013] Slowly drip the oil phase into the water phase using a cross-flow injection pump. After all the dripping is completed, stir at high speed for emulsification to form a stable emulsion.

[0014] Step 4, granulation

[0015] Reduce the rotation speed of the stirring paddle, stir well for 4-6 h, fully volatilize the remaining organic solvent, and filter to obtain solid particles, which are the required CL-20 / B / Al / PTFE composite energetic material. Put it into an oven, adjust the temperature to 40-50 °C, dry for 12-15 h and then take it out for vacuum drying and storage.

[0016] Preferably, in step 1, the mass ratio of the oil phase to the water phase is 1:3 to 1:5.

[0017] Preferably, in step 2, the prepared aqueous solution of the water phase includes at least one of the following:

[0018] An aqueous solution of PVA with a mass fraction of 2%, an aqueous solution of Tween-80 with a mass fraction of 5%, and a mixed aqueous solution of PVA with a mass fraction of 2% and Tween-80 with a mass fraction of 5%.

[0019] Preferably, in step 3, the time for high-speed stirring and emulsification is 0.5-2 h.

[0020] Preferably, in step 4, the stirring speed is 200 to 500 rpm.

[0021] Preferably, in the prepared composite energetic material, the ratio of CL-20 to TPU is fixed at 55% and 5%, the ratio of metal powder B to Al is 18% - 36%, and the ratio of PTFE is 4% - 22%; in the metal powder, B / Al is 1:2 to 2:1.

[0022] The present invention provides a CL-20 / B / Al / PTFE composite energetic material prepared by the above preparation method.

[0023] Compared with the traditional preparation method of composite energetic materials, the present invention has the following advantages:

[0024] (1) The organic solvent selected in the present invention is dichloromethane, which has a small solubility for the main explosive CL-20 and does not change the crystal form of CL-20 during the high-speed stirring and emulsification process, and the experimental conditions are mild. By changing three process conditions, namely the ratio of the water phase to the oil phase, the emulsification time, and the type of emulsifier, a composite energetic material with regular morphology, uniform component distribution, and high safety is prepared.

[0025] (2) For the composite energetic material prepared by the emulsion-suspension preparation process, the component contact area is large, the contact distance is small, heat transfer between components is sufficient, the energy release rate is faster, and the combustion performance is good. Description of the Drawings

[0026] Figure 1 It is the scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) diagrams of the CL-20 / B / Al / PTFE composite energetic material. (a) is the morphology diagram of the composite particles, (b) is the EDS diagram of aluminum element on the surface of the composite particles, (c) is the EDS diagram of boron element on the surface of the composite particles, and (d) is the EDS diagram of fluorine element on the surface of the composite particles.

[0027] Figure 2 It is the combustion pressure curve diagram of the CL-20 / B / Al / PTFE composite energetic material prepared by the emulsion suspension evaporation method.

[0028] Figure 3 It is the combustion pressure curve diagram of the CL-20 / B / Al / PTFE composite energetic material prepared by the direct method. Detailed Embodiments

[0029] The following further describes the present invention in detail with specific examples and drawings.

[0030] Example 1

[0031] (1) Preparation of the oil phase:

[0032] A small amount of TPU was added to 30 g of dichloromethane solution. After stirring well for 2 h to ensure that both were fully dissolved in dichloromethane, a certain amount of CL-20, B, Al, and PTFE were added to the dichloromethane dissolving the binder, and ultrasonic treatment was carried out for 1 h, followed by magnetic stirring for 2 h to form a uniform suspension, which was made into the oil phase;

[0033] (2) Preparation of the aqueous phase:

[0034] 8 g of PVA and 20 g of Tween-80 were added to 372 g of deionized water, heated in a water bath to 80 °C, and magnetically stirred for 2 h to fully dissolve and form a transparent and clear mixed solution of 2% PVA and 5% Tween-80 by mass fraction. It was poured into a reagent bottle, allowed to stand and cool, and then 90 g was taken for use.

[0035] (3) Emulsification

[0036] The oil phase was slowly dropped into the aqueous phase using a cross-flow injection pump. After all the dropping was completed, the rotation speed was adjusted to 1000 rpm, and high-speed stirring was carried out for 1 h for emulsification to form a stable emulsion.

[0037] Granulation

[0038] (4) Granulation

[0039] The rotation speed of the stirring paddle was reduced to 200 rpm, and it was stirred well for 6 h to fully volatilize the remaining ethyl acetate solvent. Solid particles were obtained by suction filtration, which were the required CL-20 / B / Al / PTFE composite energetic materials.

[0040] Example 2

[0041] This example was basically the same as Example 1, except that 20 g of dichloromethane was taken, and 100 g of the composite solution of 2% PVA and 5% Tween-80 was taken.

[0042] Comparative Example 1

[0043] This example was basically the same as Example 1, except that 10 g of dichloromethane was taken, and 70 g of the composite solution of 2% PVA and 5% Tween-80 was taken.

[0044] Example 3

[0045] This example was basically the same as Example 1, except that the time for high-speed stirring emulsification was 0.5 h.

[0046] Example 4

[0047] This example was basically the same as Example 1, except that the time for high-speed stirring emulsification was 1.5 h.

[0048] Comparative Example 2

[0049] This example is basically the same as Example 1, except that the time for high-speed stirring and emulsification is 2 h.

[0050] Example 5

[0051] This example is basically the same as Example 1, except that the aqueous solution is a PVA solution with a mass fraction of 2%.

[0052] Example 6

[0053] This example is basically the same as Example 1, except that the aqueous solution is a Tween-80 solution with a mass fraction of 2%.

[0054] Comparative Example 3

[0055] This example is basically the same as Example 1, except that the aqueous solution is an SDBS solution with a mass fraction of 2%.

[0056] Comparative Example 4

[0057] In this example, the traditional direct method process is adopted. CL-20, B, Al, and PTFE are added to an organic solution containing a binder, and stirred and volatilized to prepare the CL-20 / B / Al / PTFE composite energetic material.

[0058] Mechanical sensitivity test experiment: The impact sensitivity is tested using an impact sensitivity tester, and the selected model is the HGZ type impact sensitivity tester. The temperature in the laboratory should be controlled within the range of 10 °C to 35 °C, and the relative humidity should be less than 80%. In the experiment, a 10 kg hammer weight is selected for the characteristic drop height experiment, and the amount of medicine for each experiment is controlled at 50 ± 1 mg. The experimental results are shown in Table 1.

[0059] Table 1 Comparison of characteristic drop heights of samples

[0060]

[0061] Electrostatic charge accumulation amount test experiment: The friction charge amount of the CL-20 / B / Al / PTFE energetic materials prepared by different preparation processes is measured using the inclined groove method on a copper chute with an inclination angle of 45°. The length of the chute is 90 cm, and the amount of medicine for each experiment is 1 g (the error is within ±0.01). The experimental results are shown in Table 2.

[0062] Table 2 Comparison of electrostatic charge accumulation amounts of samples

[0063]

[0064] By controlling the water-oil ratio and emulsification time in the emulsion-suspension process, the optimal process for preparing the composite energetic material is obtained. The SEM images and surface element EDS images of the prepared composite particles are as follows Figure 1 shown. (a) is the morphology image of the composite particles, (b) is the EDS image of aluminum element on the surface of the composite particles, (c) is the EDS image of boron element on the surface of the composite particles, and (d) is the EDS image of fluorine element on the surface of the composite particles. The characteristic drop height of the sample in Example 1 is 23 cm, with the lowest mechanical sensitivity and the highest safety. The closed explosion experiment is carried out on it three times, and the recorder pressure combustion curve over time is as follows Figure 2 shown, and the combustion pressure curve of Comparative Example 4 is as follows Figure 3 shown. The combustion performance of the composite energetic material prepared by the emulsion-suspension process is significantly improved.

Claims

1. A method for preparing a CL-20 / B / Al / PTFE composite energetic material, characterized in that: The steps include: Step 1, preparation of oil phase: A small amount of TPU is added to dichloromethane, and stirred for 1 to 2 hours to ensure that it is fully dissolved in the solvent. A certain amount of CL-20, B, Al and PTFE are added to the organic solvent, ultrasonicated for 0.5 to 1 hour, and then stirred for 1 to 2 hours to form a uniform suspension to prepare the oil phase; Step 2, preparation of aqueous phase: Add PVA and Tween-80 to deionized water, heat in a water bath to 80-100°C, stir magnetically for 1-2 hours to make an aqueous phase solution, pour into a reagent bottle, let stand and cool before use; Step 3: Preparation of emulsion Use a cross-flow injection pump to slowly add the oil phase to the water phase. After all the additions are completed, stir at high speed to emulsify and form a stable emulsion. Step 4: Granulation Reduce the speed of the stirring blade, stir thoroughly for 4 to 6 hours, fully volatilize the remaining organic solvent, and filter and dry to obtain the solid particles, which are the required CL-20 / B / Al / PTFE composite energetic materials.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the oil phase to the water phase is 1:3 to 1:

5.

3. The preparation method according to claim 1, characterized in that: In step 2, the prepared aqueous solution includes at least one of the following: A 2% by mass PVA aqueous solution, a 5% by mass Tween-80 aqueous solution, and a 2% by mass PVA and 5% by mass Tween-80 mixed aqueous solution.

4. The preparation method according to claim 1, characterized in that: In step 3, the time of high-speed stirring emulsification is 0.5 to 2 hours.

5. The preparation method according to claim 1, characterized in that: In step 4, the stirring speed is 200-500 rpm.

6. The preparation method according to claim 1, characterized in that: The mass ratio of CL-20 to TPU in the prepared composite energetic material is fixed at 55% and 5%, the total mass ratio of metal powder B and Al is 18% to 36%, and the mass ratio of PTFE is 4% to 22%; the mass ratio of B / Al in the metal powder is 1:2 to 2:

1.

7. The CL-20 / B / Al / PTFE energetic composite material obtained by the preparation method according to claims 1 to 6.

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