Core-shell structure AP-AO composite particle as well as preparation method and application thereof

Abstract

The invention discloses an AP-AO composite particle with a core-shell structure and a preparation method and application thereof, the composite particle takes AP as a core and AO as a shell, and the mass ratio of AP to AO is (99-95): (1-5) by percentage. Compared with a traditional physical mixing method, the AO can be uniformly dispersed on the surface of the AP, and the agglomeration phenomenon of the AO is reduced; in addition, close contact between AP and AO can be promoted through preparation of the AP-AO composite particles with the core-shell structures, and the effect of AO on restraining AP thermal decomposition and the effect of reducing the burning rate of the AP / HTPB composite propellant are fully exerted.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of energetic materials, and in particular relates to a method for improving the efficiency of AO in suppressing the thermal decomposition of AP and the combustion rate of AP / HTPB composite propellant. Background Art

[0002] Composite solid propellants are widely used in ballistic missiles, rocket launches, space launch vehicles and other fields, and are the main source of power. Different uses of solid rocket engines have different requirements for the burning rate of propellants. Among them, the booster stage and cruise stage engines of multi-stage solid rockets require long-term endurance, which requires the propellant to have a low burning rate to achieve a smooth release of propellant energy, reduce energy loss during high-rate release, and increase the endurance of rocket and missile engines, thereby providing the engine with stable and long-term thrust, achieving high hit accuracy and strong destructive capability.

[0003] Among them, ammonium perchlorate (AP) is the most widely used oxidant in solid propellants, accounting for 60-90% of the propellant. Its performance directly affects the performance of the propellant. Therefore, it is very important to reduce the thermal decomposition and combustion rate of AP and improve the combustion efficiency. At present, a variety of rate reducers have been used to reduce the thermal decomposition of AP and the combustion rate of AP / HTPB composite propellants, among which ammonium oxalate (AO) is the most widely used.

[0004] At present, physical mixing and direct addition are used to reduce the thermal decomposition of AP and the combustion rate of AP / HTPB composite propellants using AO and other rate reducers. However, physical mixing makes it difficult to evenly mix AP and AO because AO has a small particle size and is prone to agglomeration; direct addition will result in poor dispersion, limited contact area with AP in the propellant component, and uneven distribution, thus limiting the role of AO in inhibiting the combustion rate. Summary of the invention

[0005] In view of the problem in the prior art that the rate reducer has a poor inhibitory effect on the thermal decomposition of AP and the burning rate of AP / HTPB composite propellants, the purpose of the present invention is to provide a core-shell structured AP@AO composite particle and a preparation method thereof, so as to solve the problem that ultrafine AO ​​is easy to agglomerate and has a poor effect on reducing the thermal decomposition of AP and the burning rate of AP / HTPB composite propellants, and to verify its inhibitory effect in the propellant.

[0006] In a first aspect, the present invention provides a core-shell structured AP@AO composite particle, wherein AP is the core and AO is the shell, and in percentage, the mass ratio of AP to AO is (99-95):(1-5).

[0007] In a second aspect, the present invention provides a method for preparing the core-shell AP@AO composite particles according to the first aspect, comprising the following steps:

[0008] Step 1: dissolving AO in a mixed solvent of ethanol and water at a certain temperature, and stirring to dissolve AO;

[0009] Step 2: Spray the AO solution obtained in step 1 evenly onto the AP particles at a certain temperature, so that AO is evenly coated on the surface of AP, and the solvent is evaporated by blowing with hot air.

[0010] Preferably, in step 1, the volume ratio of ethanol to water is (30-60):(70-40).

[0011] Preferably, in step 1, the mixed solvent of ethanol and water having a certain temperature refers to heating the mixed solvent to 60-80°C.

[0012] Preferably, in step 1, the particle size of AO is 1 to 10 μm.

[0013] Preferably, the concentration of the AO solution is 0.01 to 0.1 g / mL.

[0014] Preferably, in step 2, the AP particles having a certain temperature refer to placing the AP in a drying chamber at 50-80° C. and blowing hot air to make it evenly heated.

[0015] Preferably, in step 2, the spraying flow rate of the AO solution is 1 to 20 mL / min.

[0016] In a third aspect, the present invention provides a use of the core-shell structure AP@AO composite particles described in the first aspect in reducing the burning rate of AP / HTPB composite propellants.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) Compared with the traditional physical mixing method, the present invention can make AO evenly dispersed on the surface of AP and reduce the agglomeration of AO;

[0019] (2) The preparation of core-shell structured AP@AO composite particles can promote the close contact between AP and AO, giving full play to the role of AO in inhibiting the thermal decomposition of AP and reducing the combustion rate of AP / HTPB composite propellants. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the SEM image of raw material AP.

[0021] Figure 2 This is the SEM image of AP@AO-1% in Example 1.

[0022] Figure 3 This is the SEM image of AP@AO-2% in Example 2.

[0023] Figure 4 This is the SEM image of AP@AO-3% in Example 3.

[0024] Figure 5 This is the SEM image of AP@AO-4% in Example 4.

[0025] Figure 6 This is the SEM image of AP@AO-5% in Example 5.

[0026] Figure 7 FT-IR images of raw material AP and AP@AO composite particles in Examples 1 to 5.

[0027] Figure 8 DSC graphs of raw material AP and AP@AO composite particles in Examples 1 to 5 at 10°C / min.

[0028] Fig. 9 The combustion process diagrams are of the propellant without AO (P0), the propellant with AO added directly (P1), and the propellant with AP@AO-5% composite particles prepared in Example 5 (P2). DETAILED DESCRIPTION

[0029] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0030] In the present invention, AO can also be replaced by other rate reducers and catalysts, such as quaternary ammonium salts, carbonates, etc., and catalysts such as copper oxide and iron oxide, etc.

[0031] Example 1

[0032] A method for constructing core-shell structured AP@AO composite particles comprises the following steps:

[0033] Step 1: Prepare 100 mL of a mixed solvent of ethanol and water in a volume ratio of 45:55 and heat to 70°C;

[0034] Step 2: Dissolve 1.45 g of AO in the above-mentioned mixed solvent, and promote the dissolution of AO by stirring;

[0035] Step 3: Place 19.8 g of AP in a drying chamber at 70 °C and blow hot air to heat it evenly;

[0036] Step 4: Spray 13.79 mL of the AO mixed solvent prepared in step 1 evenly onto the AP particles, so that AO is evenly coated on the surface of AP, and blow hot air to evaporate the solvent;

[0037] Step 5: AP@AO composite particles with an AO content of 1% can be obtained through a collection bin and named AP@AO-1%.

[0038] Example 2

[0039] A method for constructing core-shell structured AP@AO composite particles comprises the following steps:

[0040] Step 1: Prepare 100 mL of a mixed solvent of ethanol and water in a volume ratio of 45:55 and heat to 70°C;

[0041] Step 2: Dissolve 1.45 g of AO in the above-mentioned mixed solvent, and promote the dissolution of AO by stirring;

[0042] Step 3: Place 19.6 g of AP in a drying chamber at 70 °C and blow hot air to heat it evenly;

[0043] Step 4: Spray 27.59 mL of the AO mixed solvent prepared in step 1 evenly onto the AP particles, so that AO is evenly coated on the surface of AP, and blow hot air to evaporate the solvent;

[0044] Step 5: AP@AO composite particles with an AO content of 2% can be obtained through a collection bin and named AP@AO-2%.

[0045] Example 3

[0046] A method for constructing core-shell structured AP@AO composite particles comprises the following steps:

[0047] Step 1: Prepare 100 mL of a mixed solvent of ethanol and water in a volume ratio of 45:55 and heat to 70°C;

[0048] Step 2: Dissolve 1.45 g of AO in the above-mentioned mixed solvent, and promote the dissolution of AO by stirring;

[0049] Step 3: Place 19.4 g of AP in a drying chamber at 70 °C and blow hot air to heat it evenly;

[0050] Step 4: Spray 41.38 mL of the AO mixed solvent prepared in step 1 evenly onto the AP particles to make AO evenly coat the surface of the AP, and blow hot air to evaporate the solvent;

[0051] Step 5: AP@AO composite particles with an AO content of 3% can be obtained through a collection bin and named AP@AO-3%.

[0052] Example 4

[0053] A method for constructing core-shell structured AP@AO composite particles comprises the following steps:

[0054] Step 1: Prepare 100 mL of a mixed solvent of ethanol and water in a volume ratio of 45:55 and heat to 70°C;

[0055] Step 2: Dissolve 1.45 g of AO in the above-mentioned mixed solvent, and promote the dissolution of AO by stirring;

[0056] Step 3: Place 19.2 g of AP in a drying chamber at 70 °C and blow hot air to heat it evenly;

[0057] Step 4: Spray 55.17 mL of the AO mixed solvent prepared in step 1 evenly onto the AP particles to make AO evenly coat the surface of the AP, and blow hot air to evaporate the solvent;

[0058] Step 5: AP@AO composite particles with an AO content of 4% can be obtained through a collection bin and named AP@AO-4%.

[0059] Example 5

[0060] A method for constructing core-shell structured AP@AO composite particles comprises the following steps:

[0061] Step 1: Prepare 100 mL of a mixed solvent of ethanol and water in a volume ratio of 45:55 and heat to 70°C;

[0062] Step 2: Dissolve 1.45 g of AO in the above-mentioned mixed solvent, and promote the dissolution of AO by stirring;

[0063] Step 3: Place 19.0 g of AP in a drying chamber at 70 °C and blow hot air to heat it evenly;

[0064] Step 4: Spray 68.97 mL of the AO mixed solvent prepared in step 1 evenly onto the AP particles, so that AO is evenly coated on the surface of AP, and blow hot air to evaporate the solvent;

[0065] Step 5: AP@AO composite particles with an AO content of 5% can be obtained through a collection bin and named AP@AO-5%.

[0066] Figure 1 to Figure 6 The SEM images of the raw material AP and the AP@AO composite particles prepared in each example show that Figure 1compared to, Figure 2 to Figure 6 AO particles can be observed adhering to the AP surface, and the AO particles are evenly dispersed on the AP surface. As the volume of the sprayed solution increases, the AO content on the AP surface also increases.

[0067] exist Figure 7 In the FT-IR spectrum of AP@AO composite particles, the characteristic peak of AO can be seen, and as the AO content increases, the signal peak intensity of AO in the composite particles increases.

[0068] Figure 8 It is the DSC graph of raw material AP and AP@AO composite particles under 10℃ / min condition, which proves that the addition of AO inhibits the low-temperature decomposition of AP and delays the low-temperature decomposition peak of AP by 2-5℃.

[0069] To further verify the speed reduction effect of AP@AO composite particles in AP / HTPB composite propellant, propellants were prepared according to the formulas in Tables 1, 2 and 3 without adding AO, directly adding AO, and AP@AO-5% prepared in Example 5 (see below for the specific preparation process). The prepared propellants were named P0, P1 and P2, respectively:

[0070] Table 1: Formulation composition of AP / HTPB composite propellant (P0) without AO

[0071]

[0072] Table 2 Formulation composition of AP / HTPB composite propellant (P1) with direct addition of AO

[0073]

[0074] Table 3: Formula components of AP / HTPB composite propellant (P2) with AP@AO composite particles prepared in Example 5

[0075]

[0076] Taking the formula in Table 3 as an example, the experimental process of AP / HTPB composite propellant is as follows: first, weigh a certain mass of HTPB and DOS and pre-mix them for 10 to 20 minutes; second, add the weighed aluminum powder to the adhesive and stir for 10 minutes to form a uniform slurry; then, add AP@AO-5% to the premixed slurry three times, and stir for 10 minutes after each addition, for a total of 30 minutes to ensure that the slurry is uniform; then, add a certain mass of IPDI and continue stirring until the mixture is uniform; then, pour the mixed slurry into a pre-prepared silicone mold and place it in a water bath oven at 60°C for curing for 7 days; finally, after it is cured and formed, take out the medicine strip for shaping for subsequent processing and testing.

[0077] Fig. 9 Table 4 and Table 5 are the combustion process and burning rate results of the prepared AP / HTPB composite propellant. Under the condition of the same length of propellant strips, the burning time of the P1 and P2 propellants with the addition of AO is prolonged, and the corresponding burning rate results in Table 4 are also reduced accordingly, which shows that the addition of AO does reduce the burning rate of the AP / HTPB composite propellant. Among them, the propellant strip containing the AP@AO-5% composite particles prepared in Example 5 has the longest burning time. According to the data in Table 4, its burning rate is 1.05 mm / s, which is about 16.7% lower than the burning rate of the P0 propellant without the addition of AO. This shows that the dispersibility of AO in the AP@AO composite particles prepared by the present invention has been significantly enhanced, so that the effect of reducing the burning rate of the AP / HTPB composite propellant is more significant.

[0078] Table 4 Burning rate results of AP / HTPB composite propellant

[0079]

[0080]

[0081] Note: P0 is the AP / HTPB composite propellant without adding AO; P1 is the AP / HTPB composite propellant with directly adding AO; P2 is the AP / HTPB composite propellant of AP@AO composite particles prepared in Example 5; the burning rate u is the average result of three measurements.

[0082] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A core-shell structure AP@AO composite particle, characterized in that: Taking AP as the core and AO as the shell, the mass ratio of AP to AO is (99-95):(1-5) in percentage.

2. A method for preparing the core-shell structure AP@AO composite particles as claimed in claim 1, characterized in that: The steps include: Step 1: dissolving AO in a mixed solvent of ethanol and water at a certain temperature, and stirring to dissolve AO; Step 2: Spray the AO solution obtained in step 1 evenly onto the AP particles at a certain temperature, so that AO is evenly coated on the surface of AP, and the solvent is evaporated by blowing with hot air.

3. The method according to claim 2, characterized in that In step 1, the volume ratio of ethanol to water is (30-60):(70-40).

4. The method according to claim 2, characterized in that In step 1, the mixed solvent of ethanol and water having a certain temperature refers to heating the mixed solvent to 60-80°C.

5. The method according to claim 2, characterized in that In step 1, the particle size of AO is 1 to 10 μm.

6. The method according to claim 2, characterized in that The concentration of AO solution is 0.01-0.1 g / mL.

7. The method according to claim 2, characterized in that In step 2, the AP particles are heated to a certain temperature by placing the AP in a drying chamber at 50 to 80° C. and blowing hot air to heat the AP particles uniformly.

8. The method according to claim 2, characterized in that In step 2, the spraying flow rate of the AO solution is 1 to 20 mL / min.

9. Use of the core-shell structure AP@AO composite particles as claimed in claim 1 in reducing the burning rate of propellants.

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