Low-pressure-index high-energy micro-smoke propellant and preparation process thereof

Abstract

The invention discloses a low-pressure-index high-energy micro-smoke propellant and a preparation process thereof.The low-pressure-index high-energy micro-smoke propellant is prepared from, by mass, 20%-30% of an adhesive system, 10%-20% of a nitramine explosive, 30%-40% of an insensitive energetic explosive, 10%-20% of a core-shell structure composite combustion rate catalyst and 0.5%-1% of a combustion stabilizer, 0.5%-1.5% of a curing agent and the balance of a functional auxiliary agent. According to the low-pressure-index high-energy micro-smoke propellant, the insensitive energetic explosive is introduced into the low-pressure-index high-energy micro-smoke propellant, the content of the nitramine explosive is reduced, and the core-shell structure composite burning rate catalyst is added on the basis, so that the safety risk of the propellant is greatly reduced, the burning rate adjustable range of the propellant is effectively widened, the burning rate pressure index is reduced to 0.55 or below from about 0.8, and meanwhile, the low-pressure-index high-energy micro-smoke propellant has the advantages that the low-pressure-index high-energy micro-smoke propellant has good application prospects. The propellant is excellent in processing property and mechanical property and low in smoke signal characteristic.

Description

Technical Field

[0001] The present invention relates to the technical field of propellants, and in particular to a low-pressure-index high-energy low-smoke propellant and a preparation process thereof. Background Art

[0002] New tactical missiles are required to possess long-range precision strike capabilities and high survivability, placing high energy and low-smoke requirements on their propulsion systems. High energy is fundamental to meeting the high efficiency and penetration capabilities required of future missiles. Trailing smoke elimination technology is key to achieving precision guidance and enhancing the survivability of tactical missiles. As missile defense systems continue to improve their ability to search, track, and destroy targets in the active phase, the trend toward low-smoke propellants for tactical missiles is inevitable. Low-smoke propellants can meet the transmission requirements of optical guidance signals, such as visible light, laser, and infrared, achieving precision guidance. They are also crucial to missile stealth technology, preventing detection by enemy radar and subsequent interception and destruction.

[0003] GAP propellants, due to their high energy, clean fuel gas, and low signature, have become the preferred choice for high-energy, low-smoke propellants. Currently, GAP propellants are widely used in tactical weapon systems and generally meet the requirements for high energy and low signature. However, the current mature GAP high-energy, low-signature propellant formulas still contain a small amount of aluminum powder, and the AP content still dominates the filler. This produces a small amount of primary smoke and a large amount of secondary smoke after combustion, and cannot achieve a low-smoke or smokeless tail plume like double-base and modified double-base propellants. Summary of the Invention

[0004] To overcome the shortcomings of the existing technology, the present invention provides a low-pressure-index, high-energy, low-smoke propellant, which solves the problems of the aluminum-free, high-nitramine GAP system caused by the lack of aluminum and high nitramine content, such as high safety risks, narrow adjustable burning rate range, and high pressure index. It can meet the technical requirements of the new generation of high-performance missile weapon systems for propellant interior ballistic performance.

[0005] The present invention solves the technical problem by adopting the following technical solutions.

[0006] The present invention provides a low-pressure index high-energy low-smoke propellant, which is made from raw material components including the following mass percentages:

[0007] Adhesive system: 20% to 30%;

[0008] Nitramine explosives: 10% to 20%;

[0009] Insensitive energetic explosives: 30% to 40%;

[0010] Core-shell structure composite burning rate catalyst: 10% to 20%;

[0011] Flame stabilizer: 0.5% to 1%;

[0012] Curing agent: 0.5%~1.5%;

[0013] Functional additives: balance

[0014] The present invention also provides a preparation process for the above-mentioned low pressure index high energy low smoke propellant, comprising:

[0015] The adhesive and plasticizer in the adhesive system are premixed to form a uniform glue solution; then the functional additive, the flame stabilizer and the glue solution are mixed, and energetic explosives, insensitive energetic explosives, core-shell structure composite burning rate catalyst and curing agent are added to the mixture in sequence, and then the uniformly mixed slurry is vacuum cast and cured.

[0016] The present invention has the following beneficial effects:

[0017] The present invention provides a low-pressure-index high-energy low-smoke propellant and a preparation process thereof. The low-pressure-index high-energy low-smoke propellant is made from the following raw material components in percentage by mass: binder system: 20% to 30%, nitramine explosive: 10% to 20%, insensitive energetic explosive: 30% to 40%, core-shell structure composite burning rate catalyst: 10% to 20%, flame stabilizer: 0.5% to 1%, curing agent: 0.5% to 1.5%, functional additive: balance. For high-nitramine systems, the above-mentioned propellant provided by the present invention partially replaces nitramine with insensitive energetic explosive and uses a core-shell structure composite burning rate catalyst. This not only greatly reduces the safety risk of the propellant, but also effectively broadens the adjustable range of its burning rate, and reduces the burning rate pressure index from about 0.8 to below 0.55, while having little effect on energy performance, process performance, mechanical properties and characteristic signals. DETAILED DESCRIPTION

[0018] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0019] The following is a detailed description of a low pressure index, high energy, low smoke propellant and its preparation process provided by an embodiment of the present invention.

[0020] In a first aspect, an embodiment of the present invention provides a low pressure index, high energy, low smoke propellant, which is made from raw material components including the following mass percentages:

[0021] Adhesive system: 20% to 30%;

[0022] Nitramine explosives: 10% to 20%;

[0023] Insensitive energetic explosives: 30% to 40%;

[0024] Core-shell structure composite burning rate catalyst: 10% to 20%;

[0025] Flame stabilizer: 0.5% to 1%;

[0026] Curing agent: 0.5%~1.5%;

[0027] Functional additives: balance

[0028] As missile propellant performance requirements continue to rise, the lower the AP content, the better—in other words, the less secondary smoke, the better. At the same time, high interior ballistic performance is also required. Therefore, existing GAP high-energy, low-signature propellants face significant challenges. Replacing AP with large amounts of explosives as the primary filler significantly increases propellant safety risks, narrows the adjustable burning rate range, and increases the pressure index, creating bottlenecks that limit their application.

[0029] To overcome the aforementioned shortcomings of the existing technology, the present invention provides a low-pressure-index, high-energy, low-smoke propellant for high-nitramine systems. This design utilizes a partially insensitive energetic explosive to replace the nitramine, along with a core-shell composite burning rate catalyst. This significantly reduces the propellant's safety risks, effectively broadens the adjustable burning rate range, and reduces the burning rate pressure index from approximately 0.8 to below 0.55, while minimizing the impact on energy performance, processability, mechanical properties, and characteristic signals. This high-energy, low-smoke propellant offers controlled safety risks and excellent performance, possessing a wide range of applications and significant practical value.

[0030] In some optional embodiments, the core-shell structure composite burning rate catalyst has an oxidant as a core and a nano burning rate catalyst as a shell, and they are connected by chemical bonding;

[0031] Preferably, the mass ratio of the oxidant to the nano burning rate catalyst in the core-shell structure composite burning rate catalyst is between 4 / 1 and 9 / 1;

[0032] Preferably, the moisture content in the core-shell structure composite combustion rate catalyst is not greater than 500 PPm.

[0033] In some optional embodiments, the oxidant is ammonium perchlorate;

[0034] Preferably, the median particle size d50 of the ammonium perchlorate is 100 μm to 300 μm.

[0035] In some optional embodiments, the nano burning rate catalyst is any one or more of lead salt, copper salt, and oxides of lead, zinc, iron, and aluminum;

[0036] Preferably, the median particle size d50 of the nano burning rate catalyst is 50 nm to 100 nm.

[0037] An embodiment of the present invention provides a low-pressure index, high-energy, low-smoke propellant. The catalyst in the propellant is a core-shell structured catalyst, which is formed by chemically bonding a nano-burning rate catalyst to the surface of an AP to form a core-shell structured composite burning rate catalyst. Compared with physical mixing, the transfer and heat transfer distance between the catalyst and the AP in the composite with a core-shell structure during the combustion of the solid propellant is shorter, the catalytic efficiency is higher, and the effect is better. At the same time, the core-shell structured composite burning rate catalyst is a micron-scale material composed of a nano-scale burning rate catalyst and a micron-scale AP in terms of microstructure, which effectively reduces the problems of deterioration of the propellant process performance caused by the direct addition of nano-scale catalysts and the low catalytic efficiency of the catalyst itself due to agglomeration. It should be noted that the core-shell structure composite burning rate catalyst used in the propellant can be prepared by self-assembly, precipitation method, microemulsion method, hydrothermal method, etc., such as CN201110312128.8, a core-shell nanocomposite material and its preparation method, CN202110656079.3 core-shell aluminum@perchlorate / catalyst composite microspheres and solid propellant based on the microspheres, etc.

[0038] In addition, no new inert additives are introduced into the core-shell structure composite burning rate catalyst of the present invention, which has basically no effect on the energy performance and mechanical properties of the propellant. The remaining components, contents and parameters in the propellant are optimized and designed to ensure that the propellant not only maintains the characteristic signal, mechanical properties and energy performance unchanged, but also has excellent process performance, effectively expanded adjustable burning rate range (the burning rate at 6.86 MPa is adjustable within the range of 8.8 mm / s to 14 mm / s) and low pressure index (pressure index n≤0.55 at 6 MPa to 12 MPa) and other excellent properties.

[0039] In some optional embodiments, the adhesive system comprises an adhesive and a plasticizer, wherein the adhesive is selected from glycidyl polyazide (GAP), and the plasticizer is selected from any one or more of nitroglycerin (NG), triethylene glycol dinitrate (TEGDN), and 1,2,4-butanetriol trinitrate (BTTN);

[0040] Preferably, the mass ratio of the plasticizer to the adhesive is between 1.0 and 3.0.

[0041] In some optional embodiments, the nitroamine explosive is any one or more of RDX or HMX, and the insensitive energetic explosive is any one or more of FOX-7 or TKX-50.

[0042] In some optional embodiments, the flame stabilizer is aluminum oxide Al2O3.

[0043] In some optional embodiments, the curing agent is one or a combination of hexamethylene diisocyanate or dimer fatty acid diisocyanate.

[0044] In some optional embodiments, the functional additives include a mechanical properties additive, a stabilizer, a flame stabilizer, and a curing catalyst. The mechanical properties additive is a neutral polymer bonding agent, the stabilizer is N,N-dimethylaniline, the flame stabilizer is titanium dioxide or zirconium carbide, and the curing catalyst is dicumyl peroxide.

[0045] In a second aspect, an embodiment of the present invention provides a preparation process for preparing the above-mentioned low pressure index high energy low smoke propellant, comprising:

[0046] The adhesive and plasticizer in the adhesive system are premixed to form a uniform glue solution; then the functional additive, the flame stabilizer and the glue solution are mixed, and energetic explosives, insensitive energetic explosives, core-shell structure composite burning rate catalyst and curing agent are added to the mixture in sequence, and then the uniformly mixed slurry is vacuum cast and cured.

[0047] In some optional embodiments, the vacuum casting temperature is 50° C. to 60° C., and after casting, the material is cured at 45° C. to 55° C. for at least 5 days.

[0048] The present invention will be further described below with reference to the embodiments.

[0049] Example 1

[0050] Propellant composition (mass percentage)

[0051] Formula composition Content / wt.% GAP 13.5 NG / TEGDN 13.5 FOX-7 36.5 HMX 15 Core-shell structure composite burning rate catalyst 18 <![CDATA[Combustion stabilizer Al2O3]]> 0.5 Curing agent + functional additives 3.0

[0052] The mass ratio of AP to nano-combustion rate catalyst in the core-shell structure composite combustion rate catalyst is 8 / 1. The combustion rate is 10.3 mm / s at 6.86 MPa, and the pressure index is 0.48 at 6-12 MPa.

[0053] Example 2

[0054] (1) Propellant composition (mass percentage)

[0055] Formula composition Content / wt.% GAP 10.8 NG / BTTN 16.2 FOX-7 35 RDX 20 Core-shell structure composite burning rate catalyst 15 <![CDATA[Combustion stabilizer Al2O3]]> 0.5 Curing agent + functional additives 2.5

[0056] (2) Combustion performance of propellant

[0057] The mass ratio of AP to nano-combustion rate catalyst in the core-shell structure composite combustion rate catalyst is 4 / 1. The combustion rate is 11.7 mm / s at 6.86 MPa, and the pressure index is 0.52 at 6-12 MPa.

[0058] Example 3

[0059] (1) Propellant composition (mass percentage)

[0060] Formula composition Content / wt.% GAP 15 TEGDN 15 TKX-50 46.5 HMX 10 Core-shell structure composite burning rate catalyst 10 <![CDATA[Stable combustion promoter Al2O3]]> 1.0 Curing agent + functional additives 2.5

[0061] (2) Combustion performance of propellant

[0062] The mass ratio of AP to nano-combustion rate catalyst in the core-shell structure composite combustion rate catalyst is 4 / 1. The combustion rate is 8.8 mm / s at 6.86 MPa, and the pressure index is 0.49 at 6-12 MPa.

[0063] Example 4

[0064] (1) Propellant composition (mass percentage)

[0065]

[0066]

[0067] (2) Combustion performance of propellant

[0068] The mass ratio of AP to nano-combustion rate catalyst in the core-shell structure composite combustion rate catalyst is 9 / 1. The combustion rate is 13.8 mm / s at 6.86 MPa, and the pressure index is 0.54 at 6-12 MPa.

[0069] Example 5

[0070] (1) Propellant composition (mass percentage)

[0071] Formula composition Content / wt.% GAP 12 NG / BTTN 18 FOX-7 36.5 HMX 18 Core-shell structure composite burning rate catalyst 12 <![CDATA[Combustion stabilizer Al2O3]]> 1.0 Curing agent + functional additives 2.5

[0072] (2) Combustion performance of propellant

[0073] The mass ratio of AP to nano-combustion rate catalyst in the core-shell structure composite combustion rate catalyst is 5 / 1. The combustion rate is 9.6 mm / s at 6.86 MPa, and the pressure index is 0.53 at 6-12 MPa.

[0074] Example 6

[0075] (1) Propellant composition (mass percentage)

[0076] Formula composition Content / wt.% GAP 10.8 NG / TEGDN 16.2 TKX-50 36 HMX 18 Core-shell structure composite burning rate catalyst 16 <![CDATA[Combustion stabilizer Al2O3]]> 0.5 Curing agent + functional additives 2.5

[0077] (2) Combustion performance of propellant

[0078] The mass ratio of AP to nano-combustion rate catalyst in the core-shell structure composite combustion rate catalyst is 7 / 1. The combustion rate is 10.2 mm / s at 6.86 MPa, and the pressure index is 0.51 at 6-12 MPa.

[0079] Example 7

[0080] (1) Propellant composition (mass percentage)

[0081] Formula composition Content / wt.% GAP 10 TEGDN 20 TKX-50 35 HMX 15 Core-shell structure composite burning rate catalyst 17 <![CDATA[Stable combustion promoter Al2O3]]> 0.5 Curing agent + functional additives 2.5

[0082] (2) Combustion performance of propellant

[0083] The mass ratio of AP to nano-combustion rate catalyst in the core-shell structure composite combustion rate catalyst is 6 / 1. The combustion rate is 9.3 mm / s at 6.86 MPa, and the pressure index is 0.52 at 6-12 MPa.

[0084] Comparative Example 1

[0085] (1) Propellant composition (mass percentage)

[0086] Formula composition Content / wt.% GAP 13.5 NG / TEGDN 13.5 HMX 51.5 Nanocombustion rate catalyst 2 AP 16 <![CDATA[Stable combustion promoter Al2O3]]> 0.5 Curing agent + functional additives 3.0

[0087] (2) Combustion performance of propellant

[0088] The burning rate is 9.1 mm / s at 6.86 MPa, and the pressure index is 0.73 at 6-12 MPa.

[0089] Comparative Example 2

[0090] (1) Propellant composition (mass percentage)

[0091]

[0092]

[0093] (2) Combustion performance of propellant

[0094] The burning rate is 8.8 mm / s at 6.86 MPa, and the pressure index is 0.61 at 6-12 MPa.

[0095] From the experimental results of the above embodiments and comparative examples, it can be seen that the solid propellant prepared by the embodiment of the present invention has an adjustable burning rate within the range of 8.8 mm / s to 14 mm / s at 6.86 MPa, and a pressure index n≤0.55 at 6 MPa to 12 MPa. However, in Comparative Examples 1 or 2, where the nano-burning rate catalyst and oxidant are directly mixed with other ingredients, the adjustable burning rate range of the solid propellant is narrow and the pressure index is increased, which seriously limits its application.

[0096] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A low pressure index low smoke propellant, characterized in that: It is made of raw materials with the following mass percentage contents: Adhesive system: 20% to 30%; Nitramine explosives: 10% to 20%; Insensitive energetic explosives: 30% to 40%; Core-shell structure composite burning rate catalyst: 10% to 20%; Flame stabilizer: 0.5% to 1%; Curing agent: 0.5%~1.5%; Functional additives: balance 2. The propellant according to claim 1, characterized in that The core-shell structure composite burning rate catalyst has an oxidant as a core and a nano burning rate catalyst as a shell, and they are connected by chemical bonding; Preferably, the mass ratio of the oxidant to the nano burning rate catalyst in the core-shell structure composite burning rate catalyst is between 4 / 1 and 9 / 1; Preferably, the moisture content in the core-shell structure composite combustion rate catalyst is not greater than 500 PPm.

3. The propellant according to claim 2, characterized in that The oxidant is ammonium perchlorate; Preferably, the median particle size d50 of the ammonium perchlorate is 100 μm to 300 μm.

4. The propellant according to claim 2, characterized in that The nano combustion rate catalyst is any one or more of lead salt, copper salt, and oxides of lead, zinc, iron, and aluminum; Preferably, the median particle size d50 of the nano burning rate catalyst is 50 nm to 100 nm.

5. The propellant according to claim 1, characterized in that The adhesive system comprises an adhesive and a plasticizer, wherein the adhesive is selected from glycidyl polyazide (GAP), and the plasticizer is selected from any one or more of nitroglycerin (NG), triethylene glycol dinitrate (TEGDN), and 1,2,4-butanetriol trinitrate (BTTN); Preferably, the mass ratio of the plasticizer to the adhesive is between 1.0 and 3.

0.

6. The propellant according to claim 1, characterized in that The nitramine explosive is any one or more of RDX or HMX, and the insensitive energetic explosive is any one or more of FOX-7 or TKX-50.

7. The propellant according to claim 1, characterized in that The flame stabilizer is aluminum oxide Al2O3.

8. The propellant according to claim 1, characterized in that The curing agent is one of hexamethylene diisocyanate and dimer fatty acid diisocyanate, or a combination thereof.

9. A process for preparing a low pressure index high energy low smoke propellant, characterized in that: The low pressure index high energy low smoke propellant according to any one of claims 1 to 8 is prepared, comprising: The adhesive and plasticizer in the adhesive system are premixed to form a uniform glue solution; then the functional additive, the flame stabilizer and the glue solution are mixed, and energetic explosives, insensitive energetic explosives, core-shell structure composite burning rate catalyst and curing agent are added to the mixture in sequence, and then the uniformly mixed slurry is vacuum cast and cured.

10. The preparation process according to claim 9, characterized in that: The vacuum pouring temperature is 50° C. to 60° C., and after pouring, the mixture is cured at 45° C. to 55° C. for at least 5 days.

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