CN116217314A

CN116217314A - Composite energetic particle and preparation method thereof

Info

Publication number: CN116217314A
Application number: CN202310454526.6A
Authority: CN
Inventors: 郝俸; 韩立坤; 王伟; 杨育文; 颜菁; 唐泉; 王业腾; 赵杭; 卢辉
Original assignee: Naval University of Engineering PLA; Hubei Institute of Aerospace Chemical Technology
Current assignee: Naval University of Engineering PLA; Hubei Institute of Aerospace Chemical Technology
Priority date: 2023-04-25
Filing date: 2023-04-25
Publication date: 2023-06-06
Anticipated expiration: 2043-04-25
Also published as: CN116217314B

Abstract

The invention provides a composite energetic particle and a preparation method thereof, wherein the composite energetic particle comprises ADN (1), AP (2), sulfolane (3) and a stabilizer (4); the ADN is incompletely coated by sulfolane; the coated particles and AP form a mixed structure, the stabilizer is filled in the pores of the mixed structure to form a spherical structure, and the components are as follows by weight: 100 parts of ADN, 30-400 parts of AP, 1-2 parts of sulfolane and 0.5-1 part of stabilizer; the stabilizer comprises magnesium nitrate (5) and active carbon (6), wherein the mass content of the magnesium nitrate is 78-90%, and the mass content of the active carbon is 10-22%. The product of the invention is used as an energetic component in composite explosive and composite propellant.

Description

Composite energetic particle and preparation method thereof

Technical Field

The invention belongs to the technical field of composite explosives and composite propellants, and relates to composite energetic particles and a preparation method thereof, which are used as energetic components in the composite explosives and the composite propellants.

Technical Field

The composite solid propellant mainly comprises strong oxidant, combustion agent, adhesive, curing agent and other components, is an important power source for realizing remote striking of weapons, completing satellite emission and space exploration, and plays a very important role in national defense modern construction and national economy development.

Dinitramide ammonium (NH) ₄ N(NO ₂ ) ₂ ADN for short) is a high-energy strong oxidant, does not contain halogen, has relatively clean thermal decomposition combustion products (such as nitrogen and water), and does not have the problems of propellant characteristic signal enhancement, acid mist or acid rain pollution and the like caused by HCl and the like. ADN also has the advantage of high energy, which can significantly increase the energy of the propellant. The ADN has wide application prospect in high-energy, green and low-characteristic signal propellants. However, ADN is very hygroscopic and is prone to agglomeration, which results in deterioration of the propellant processing properties and difficulty in efficient processing and forming, which is a key technical problem limiting large-scale practical application. In addition, the sensitivity of ADN after moisture absorption is higher, so that the safety risk of the propellant in the process of processing, manufacturing, transporting and using is increased.

In order to solve the problem of moisture absorption of ADN and accelerate the application of ADN, a great deal of physicochemical modification is carried out in the industry, and the method mainly comprises the methods of sphericizing, surface coating, eutectic and the like. Spherical ADN is prepared by adopting atomization crystallization or emulsion crystallization sphericizing technologies in Russian, america, germany, swedish and other countries, the hygroscopicity of the ADN is reduced, and the sphericizing preparation of the ADN is realized in recent years in China, but the practical application of the spherical ADN is still not achieved in large scale due to the strong hygroscopicity in practical environments.

Surface coating is another effective approach to improve the hygroscopicity of ADN. The research workers at home and abroad use polymer adhesives (such as hydroxyl-terminated polybutadiene, ethylcellulose and the like), coupling agents (such as KH-550), surfactants (such as octadecylamine), paraffin, stearic acid, graphene and the like to coat ADN in a large number, but the ADN still cannot be eliminated.

In order to solve the influence of ADN moisture absorption on energy and safety and maintain the energy advantage of ADN, common practice in industry is to wrap the surface of ADN with energy-containing materials such as AP and HMX through a eutectic structure or a cladding structure, reduce the contact between ADN and air and improve the moisture absorption resistance of ADN. However, these measures merely reduce contact by physical isolation, and risk increases dramatically once the energetic material is exposed.

The above system does not address the impact of ADN moisture absorption on energy and safety, simply by reducing contact through physical isolation, and risk increases dramatically once the energetic material is exposed. Meanwhile, the introduction of a large amount of inert bodies can also cause the reduction of ADN energy, and simultaneously can prevent the thermal decomposition of ADN and the combustion chemical reaction with other components of the propellant, so that the combustion performance of the propellant is greatly influenced and is uncontrollable, the energy release of the propellant is further influenced, and the performance of the propellant cannot meet the design index requirements and cannot be used.

Disclosure of Invention

In order to overcome the defects of the background technology, the invention provides a composite energetic particle and a preparation method thereof, wherein two high-energy energetic materials are adopted to prepare the composite particle, so that the influence of ADN moisture absorption on safety is reduced.

The researchers of the invention find through a large number of researches on the hygroscopicity of ADN: firstly, the hygroscopic process of ADN is divided into two steps, wherein the first step is that ADN and moisture in air form a crystalline state, and the second step is that the self-adsorption of crystal water enables ADN to be dissolved in water to form a viscous slurry state. ADN in a viscous slurry state is high in sensitivity and poor in formability, so that abnormal combustion points are formed on the propellant locally; second, the exposed anions and cations on the ADN crystal surface are related to hygroscopicity: the lower the hygroscopicity when the ADN surface is negatively charged or electrically neutral, the greater the number of cations exposed, the greater the hygroscopicity, with lower hygroscopicity for the (0,2,0) and (1, 0) crystal planes. From the stability perspective, the general knowledge in the industry is that the larger the density of the initiated bonds of the crystal face is, the lower the sensitivity is, and the safer the explosive is. ADN has an induced bond density at 5 important crystal planes: (0,2,0) > (1, 0) > (0, 1) > (1, 0) > (1, -1), the order of initiation of bond energies is from large to small: (0,2,0) > (1, 0) > (1, 0) > (0, 1) > (1, -1). In order to reduce the hygroscopicity of ADN and improve the safety, the proportion of the (0,2,0) crystal face and the (1, 0) crystal face should be increased, and the proportion of the (1, -1) crystal face should be reduced.

Based on the above study, the present invention proposes a hypothesis that ADN is allowed to crystallize with moisture in the air, but that the crystallization water of ADN is controlled not to self-adsorb, maintaining the high energy and safety properties of ADN. From this assumption, analysis of the differences between the (0,2,0) and (1, -1) crystal planes reveals that the N-N bonds in ADN are the longest in length as initiating bonds, the most active in chemical bonds, the weakest in bond strength, the smallest in initiating bond density of the (1, -1) crystal planes, and the largest in surface free energy, and are most likely to fracture in the crystallographic direction to form cleavage planes.

Based on the above assumption, the present invention innovatively proposes a concept: a composite structure is designed, which consists of ADN and a stabilizer, when the composite structure is wet, the characteristic that the free energy of the N-N bond surface of a (1, -1) crystal face is the largest is utilized according to the surface chemistry theory, and the stabilizer and the (1, -1) crystal face of the ADN are designed to share crystal water, and the crystal water is locked.

The design idea of the invention is as follows: the invention designs a composite energetic particle, which comprises Ammonium Dinitramide (ADN), AP, sulfolane and a stabilizer, wherein the stabilizer comprises magnesium nitrate and active carbon. The ammonium dinitrate is incompletely coated by sulfolane. Sulfolane, also known as tetrahydrothiophene-1, 1-dioxide, has a chemical formula of C4H8O2S, is colorless transparent liquid, is an excellent aprotic polar solvent, and can be mutually dissolved with water, acetone, toluene and the like. Sulfolane has a melting point of 25-30 deg.c and is coated on the surface of ADN in liquid form at high temperature to form incomplete coating. When the temperature is reduced, the sulfolane density is increased, shrinkage is condensed at the depressions of the surface of the ADN, and the surface defect and the water absorption capacity of the ADN are reduced. The coated composite particles and AP are mixed mechanically, and then stabilizer is added for secondary mixing.

The technical scheme of the invention is that a composite energetic particle is designed, and the composite energetic particle comprises ammonium dinitramide, AP, sulfolane and a stabilizer; the ammonium dinitrate is coated by sulfolane, and the coated composite particles and AP form a mixed structure; the stabilizer is filled in the pores of the mixed structure, and the composite energetic particles integrally form a spherical structure.

Further, the weight portions of the components are as follows: dinitramide ammonium: 100 parts; ammonium perchlorate: 30-400 parts of: sulfolane: 1-2 parts; stabilizer: 0.5 to 1 part.

The proportion of the dinitramide ammonium and the ammonium perchlorate is mainly used for meeting the oxygen balance requirement of the composite particles and ensuring the working capacity of the particles.

When the mass ratio of sulfolane to dinitramide ammonium is 1: in the process 1, the thickness of the completely and uniformly coated sulfolane film layer is 1-10 microns, and considering that the process is difficult to realize completely and uniformly coating and the film layer is possibly damaged in the use process of the particles, the invention does not pursue the integrity of the film layer, and the incomplete film layer is purposefully designed or the incomplete coating of the film layer is allowed to occur. The amount of sulfolane and stabilizer is the minimum amount determined based on theoretical analysis and experimentation to reduce the loss of energy from the additive to the particles. The sulfolane is wrapped on the surface of the ADN in a liquid form under the high temperature condition, when the temperature is reduced, the density of the sulfolane is increased, shrinkage is condensed at the concave position of the surface of the ADN, AND when the ambient temperature is changed in daily temperature, the sulfolane repeatedly melts AND solidifies, so that the surface defect of the ADN is reduced in a deformation memory mode, the sulfolane is tightly attached to the surface of the ADN, AND the water absorption resistance of the AND is improved.

Further, the stabilizer comprises magnesium nitrate and activated carbon; wherein, the mass content of the magnesium nitrate is 78-90 percent, and the mass content of the active carbon is 10-22 percent.

Further, the stabilizer has a structure that an outer layer is magnesium nitrate and an inner layer is an active carbon surface.

When the composite structure encounters moisture in the air, the magnesium nitrate absorbs water preferentially to the (1, -1) crystal face of ADN, so that crystal water is formed by absorbing water first, the crystallized magnesium nitrate is condensed on the surface of AND in a solid state, AND the surface structure of the crystallized magnesium nitrate prevents the moisture in the air from further corroding. In order to improve the surface peeling strength of the crystallized magnesium nitrate AND the AND, a structure that activated carbon is coated on the surface of the magnesium nitrate is adopted, AND in the grinding process, the granularity of the activated carbon is far smaller than that of the magnesium nitrate, AND the activated carbon is inlaid between the magnesium nitrate AND the AND. Meanwhile, the surface of the activated carbon is smooth, AND the safety of magnesium nitrate AND AND particles in the impact friction process is reduced.

Further, the composite energetic particle comprises the following components in parts by weight: dinitramide ammonium: 100 parts; ammonium perchlorate: 50 parts; sulfolane: 1.4 parts; stabilizer: 0.7 parts; the stabilizer comprises 85% of magnesium nitrate by mass and 15% of active carbon by mass.

The invention also provides a preparation method of the particles, which is realized by adopting a coating and mechanical grinding mode.

The preparation method of the invention comprises the following steps:

step one: sulfolane coated dinitramide ammonium: dissolving sulfolane in absolute ethyl alcohol, adding ammonium dinitrate, stirring and heating until the material presents a slurry state, sieving, and cooling to room temperature under vacuum condition to form coated particles;

step two: mechanical grinding: in a grinding chamber containing a grinding ball; adding the coated particles prepared in the first step and ammonium perchlorate and a stabilizer into a grinding cavity; and discharging the ground slurry through a discharge hole of the grinding cavity to obtain mixed particles.

Further, in the first step, in the stirring and heating operation, the stirring speed is 30-100 r/min, and the heating temperature is 50-60 ℃; stirring and heating for 15-100 r/min. (mainly with respect to ambient temperature, moderation, barometric pressure and heat dissipation capacity of the device, actual time is difficult to determine, visually

In the second step, the grinding balls are polytetrafluoroethylene grinding balls with the particle size of 12 mm.

Further, in the second step, the grinding process parameters are as follows: the grinding speed is 3-7r/min and the time is 10-20 minutes.

The traditional coating requires 100% of the coating to be effective, the coating is not completed, and the actual performance is reduced. According to the invention, the sulfolane is coated on the surface of the particle in the coating process, the complete coating can be realized by theoretically adopting the proportion of the invention, the complete coating effect is obviously superior to that of incomplete coating, but the coating film layer can be damaged in the grinding or using process, and the invention allows the particle to be naked and leaked. Mechanical milling allows the particles to self-assemble according to shape and size to form spherical particles.

The invention has the advantages compared with the prior art that:

(1) According to the invention, sulfolane is adopted to directionally coat the surface of ammonium dinitrate, and the composite particles only absorb moisture once in the air, and the hygroscopicity is less than 5%;

(2) The invention adopts the mixture of magnesium nitrate and active carbon as the stabilizer, has the advantage of low sensitivity, and improves the characteristic drop height of the composite particles by more than 50 percent.

Drawings

FIG. 1 is a schematic diagram of the structure of a composite energetic particle.

FIG. 2 is a schematic diagram showing the composition of a stabilizer according to an embodiment of the present invention.

FIG. 3 is the hygroscopicity profile of the products and raw materials of example 1, comparative example 1 and comparative example 2 of the present invention.

FIG. 4 is an SEM curve of the product obtained in example 1 of the present invention after 72 hours of moisture absorption

In the figure, 1-ADN,2-AP, 3-sulfolane, 4-stabilizer, 5-magnesium nitrate and 6-active carbon.

Detailed Description

The present invention will be described in further detail with reference to specific examples.

The product of the invention is prepared according to the following method:

step one: sulfolane coated dinitramide ammonium: dissolving sulfolane in absolute ethyl alcohol, adding ammonium dinitrate, stirring at low speed, heating to 50-60 deg.c, stirring at 30-100 r/min until the material is in sand pulp state, sieving, vacuum cooling to room temperature to form coated particle.

Step two: mechanical grinding: pouring polytetrafluoroethylene grinding balls with the particle size of 12mm into a grinding cavity; adding the coated particles prepared in the first step, AP and a stabilizer into a grinding cavity; grinding for 15 minutes at the grinding speed of 5r/min, and discharging the ground slurry through a discharge hole of a grinding cavity to obtain mixed particles.

Example 1

The composite energetic particle comprises the following raw materials in parts by weight: 100 parts of ADN, 50 parts of AP, 1.4 parts of sulfolane and 0.7 part of stabilizer; in the stabilizer, the content of magnesium nitrate is 85 percent and the content of active carbon is 15 percent.

The structural schematic of the product is shown in figure 1, and the ammonium dinitrate 1 is coated by the sulfolane 3, because the quantitative ratio of the sulfolane 3 is designed and controlled, part of particles of the coated ammonium dinitrate 1 are exposed; the coated particles and ammonium perchlorate 2 form a mixed structure; the stabilizer 4 is filled in the pores of the mixed structure, and the structure of the stabilizer with the spherical structure formed by the composite energetic particles as a whole is shown in fig. 2: the stabilizer has the structure that the outer layer is magnesium nitrate 5, and the inner layer is active carbon surface 6.

Example 2

The composite energetic particle comprises the following raw materials in parts by weight: 100 parts of ADN, 30 parts of AP, 2 parts of sulfolane and 0.5 part of stabilizer; in the stabilizer, the magnesium nitrate content is 78 percent and the active carbon content is 22 percent.

Example 3

The composite energetic particle comprises the following raw materials in parts by weight: 100 parts of ADN, 400 parts of AP, 1 part of sulfolane and 1.0 part of stabilizer; in the stabilizer, the content of magnesium nitrate is 90 percent and the content of active carbon is 10 percent.

Comparative example 1

The relevant components of this example are the same as in example 1, with the surfactant octadecylamine replacing sulfolane.

Comparative example 2

The relevant components of this example are the same as in example 1, the stabilizer comprising only magnesium nitrate and no activated carbon.

Evaluation of Performance

(1) Hygroscopicity test: the absolute moisture absorption rates of the raw material ADN and the examples 1, comparative examples 1 and 2 were tested by referring to the national army standard "GJB77A-1997 explosive balancer method", and the specific test method is: drying the sample in a vacuum drying oven at 50 ℃ until the weight is constant, weighing 5-10 g of the dried sample until the weight is constant, measuring the weight gain rate of the sample with time variation, wherein the weight gain measuring precision is 0.001g, and the testing condition is that the ambient temperature is 30 ℃ and the humidity is 75%. The results are shown in FIG. 3.

As can be seen from FIG. 3, in example 1 of the present invention, hygroscopicity was greatly lowered to 4.2% with respect to the raw material ADN, and the hygroscopicity was not changed after 24 hours, whereas the weight of the raw material ADN was continuously increased during the moisture absorption, and became a viscous state after 72 hours. Example 1 remained granular at 72 hours. The effectiveness of the sulfolane and the stabilizer adopted in the technical scheme of the invention is also verified in the experiment. In comparative example 1, after the surfactant octadecylamine replaced sulfolane, not only was the decrease in hygroscopicity insignificant, but the hygroscopic process continued to increase. In comparative example 2, the moisture absorption rate was more than 5% although secondary moisture absorption did not occur after the activated carbon in the stabilizer was canceled. The stabilizer designed by the invention has obvious effect.

(2) Impact sensitivity test: the samples were tested for impact sensitivity according to the method in GJB770B-2005 "powder test method" 601.2. The test conditions were drop weight 5kg, drug amount (50.+ -.1) mg, test temperature (293.15.+ -.2) K, relative humidity (60.+ -.5)%, and impact sensitivity was characterized by characteristic drop height (H50). The results are shown in Table 1.

TABLE 1 impact sensitivity test results

	H50/cm	S/cm
			ADN	18.75	0.04
Example 1	36.45	0.08
			Example 2	34.00	0.05
Example 3	38.62	0.08
			Comparative example 1	29.14	0.04

As can be seen from table 1, the embodiments employed in the present invention significantly reduced the impact sensitivity of ADN, while demonstrating the effectiveness of sulfolane and activated carbon.

(3) SEM: the particles of example 1 were subjected to a scanning electron microscope analysis after being hygroscopic for 72 hours, and the results are shown in FIG. 4. As can be seen from the figure, the invention remains in a granular form after moisture absorption, and no secondary moisture absorption occurs to generate a viscous slurry state.

Through the performance analysis, the composite particles prepared by the invention only absorb moisture once in the air, and the hygroscopicity is less than 5%; the invention has the advantage of low sensitivity, and the characteristic drop height of the composite particles is improved by more than 100%.

The foregoing description of embodiments of the invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the various embodiments described. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A composite energetic particle, characterized in that the composite energetic particle comprises dinitramide ammonium (1), ammonium perchlorate (2), sulfolane (3) and stabilizer (4);

the dinitrate amide ammonium (1) is coated by the sulfolane (3);

the coated composite particles and ammonium perchlorate form a mixed structure, and the stabilizer (4) is filled in the pores of the mixed structure;

the composite energetic particles are integrally formed into a spherical structure.

2. The composite energetic particle of claim 1, wherein the weight parts of each composition are as follows:

dinitramide ammonium: 100 parts;

ammonium perchlorate: 30-400 parts of:

sulfolane: 1-2 parts;

stabilizer: 0.5 to 1 part.

3. Composite energetic particle according to claim 1, characterized in that the stabilizer comprises magnesium nitrate (5) and activated carbon (6); wherein, the mass content of the magnesium nitrate is 78-90 percent, and the mass content of the active carbon is 10-22 percent.

4. A composite energetic particle according to claim 3, wherein the stabilizer has the structure of an outer layer of magnesium nitrate (5) and an inner layer of activated carbon surface (6).

5. The composite energetic particle according to claim 2, wherein the weight parts of each composition are as follows:

dinitramide ammonium: 100 parts;

ammonium perchlorate: 50 parts;

sulfolane: 1.4 parts;

stabilizer: 0.7 parts;

the stabilizer comprises 85% of magnesium nitrate by mass and 15% of active carbon by mass.

6. A method of preparing the composite energetic particle according to any one of claims 1 to 5, comprising the steps of:

7. The method for preparing composite energetic particles according to claim 6, wherein in the first step, the stirring speed is 30-100 r/min and the heating temperature is 50-60 ℃ in the stirring and heating operation; stirring and heating for 15-100 r/min.

8. The method of producing composite energetic particles according to claim 6, wherein in the second step, the grinding balls are polytetrafluoroethylene grinding balls having a particle size of 12 mm.

9. The method of claim 6, wherein in the second step, the grinding process parameters are as follows: the grinding speed is 3-7r/min and the time is 10-20 minutes.