High-explosion-heat firework propellant powder based on multi-interface enhanced structure and preparation method thereof

Abstract

The invention relates to a high-explosion-heat firework propellant based on a multi-interface reinforced structure and a preparation method thereof, and belongs to the technical field of firework propellants. Coarse Al powder and coarse Mg powder are ground into micron-sized powder, and then a binder is added to obtain modified metal powder; reacting boric acid with a silane coupling agent and polytetrafluoroethylene to obtain modified polytetrafluoroethylene; the preparation method comprises the following steps: dissolving polyvinylidene fluoride in dimethylformamide, and adding micro-nano boron powder to obtain PVDF modified high-energy boron powder; and the modified metal powder, the modified polytetrafluoroethylene, the high-energy boron powder and the high-explosion-heat additive are mixed to obtain the high-explosion-heat firework propellant powder based on the multi-interface enhanced structure. According to the method, the problem that the combustion rate of metal propellant powder taking metal powder as a combustible agent is low can be solved, the reaction efficiency can be greatly improved, the explosion heat of the firework propellant powder is remarkably improved, and the method has a good application prospect in the field of propellant powder for fireworks and crackers.

Description

Technical Field

[0001] The invention relates to a high-explosive thermal firework propellant based on a multi-interface enhanced structure and a preparation method thereof, belonging to the technical field of firework propellants. Background Art

[0002] The innovation and development of fireworks and firecrackers are mainly attributed to the invention of black powder. To this day, black powder is still widely used in the field of fireworks and firecrackers. However, its defects in safety and environmental friendliness have become an important factor affecting the development of fireworks and firecrackers technology and industry. Black powder has high mechanical sensitivity, flame sensitivity and electrostatic spark sensitivity. It may explode when it is subjected to strong impact or friction, encounters open flames, or encounters electrostatic sparks caused by dry weather. Therefore, black powder has certain dangers in the production, storage, transportation and use of the process, which is easy to cause safety accidents and unexpected disasters, causing significant losses to people's lives and property.

[0003] Nowadays, the research on pyrotechnic agent formulation is developing in the direction of new materials, new processes and new principles. Against this technical background, a new propellant formulation based on active materials and prepared by wet coating-extrusion granulation process came into being. The mechanism of action of this formula is to utilize the violent oxidation-reduction reaction between active metals and fluoropolymers to instantly release a large amount of heat, generate a high temperature of more than 3000°C, and do work on the expansion of air. This oxidation-reduction reaction is self-sustaining, does not require the participation of oxygen, and there is no sulfur or nitrogen in the raw materials, so it has great potential in the development of safe and environmentally friendly fireworks propellants. Compared with black powder, the new propellant has excellent comprehensive performance, especially in terms of safety and environmental performance. Summary of the invention

[0004] The present invention relates to a high-explosive thermal fireworks propellant based on a multi-interface reinforcement structure and a preparation method thereof. The multi-interface reinforcement structure is obtained by attaching polytetrafluoroethylene on the surface of an ultrafine metal, and an aluminothermic high-explosive thermal additive and a binder are added. The contact area between an oxidant and a metal fuel is enhanced, and the mass transfer distance is shortened to improve the reaction efficiency, so as to obtain the high-explosive thermal fireworks propellant. The high-explosive thermal fireworks propellant has good application prospects in the field of propellants for fireworks and firecrackers.

[0005] The present invention is achieved through the following technical solutions.

[0006] The high-explosive thermal fireworks propellant based on the multi-interface enhanced structure is obtained by the following preparation method, which comprises the following steps:

[0007] (1) drying coarse Al powder and coarse Mg powder and mixing them in a mass ratio of 2 to 5, grinding them into micron-sized powder in a ball mill at a speed of 500 r / min, adding a binder, and continuing to ball mill at a speed of 500 r / min for 0.5 to 1 h to obtain modified metal powder;

[0008] (2) dissolving boric acid and a silane coupling agent in an ethanol solution at a mass ratio of 5 to 10, adding polytetrafluoroethylene, stirring thoroughly, heating to 80° C., reacting for 1 to 2 hours, filtering, and drying to obtain modified polytetrafluoroethylene;

[0009] (3) dissolving polyvinylidene fluoride (PVDF) in dimethylformamide to prepare a solution with a mass concentration of 5% to 10%, adding micro-nano boron powder, maintaining it in an ultrasonic environment at 80 to 100° C. for 0.5 to 1 hour, and then magnetically stirring it for 5 to 10 hours to uniformly disperse the boron powder, and filtering, washing, and drying to obtain PVDF-modified high-energy boron powder;

[0010] (4) Adding the modified polytetrafluoroethylene obtained in step (2) and the high-energy boron powder obtained in step (3) to the modified metal powder obtained in step (1), and then adding a high-explosive thermal additive, placing the mixture in a ball mill and mixing it at a speed of 500 r / min for 1 to 2 hours to obtain a high-explosive thermal fireworks propellant with a multi-interface enhanced structure.

[0011] Furthermore, the materials are configured according to the following weight portions:

[0012] 30-75 parts of modified polytetrafluoroethylene, 25-70 parts of modified metal powder, 5-10 parts of high explosive thermal additive, 5-10 parts of high energy boron powder, and 0.5-5 parts of binder.

[0013] Wherein, the high explosive thermal additive is one or more combinations of copper oxide, iron oxide, ferroferric oxide and manganese dioxide.

[0014] The adhesive is one or more combinations of fluororubber, silicone rubber, fluorosilicone rubber, polyester and polyurethane.

[0015] The silane coupling agent is one or more combinations of trimethoxysilane, triethoxysilane, tri-n-propoxysilane and tri-n-butoxysilane.

[0016] The mass ratio of steel balls to materials in the ball milling process is 4:1.

[0017] The specific beneficial effects of the present invention are:

[0018] (1) The present invention uses ultrafine metal powder and polytetrafluoroethylene to construct a multi-interface enhancement structure, which solves the problem of slow burning rate of metal propellants using metal powder as combustibles. The fireworks propellant composed of polytetrafluoroethylene, Mg powder and Al powder has multiple heterogeneous interfaces between phases, and the different environments of the molecules at the interface and the internal molecules lead to different properties. The use of ultrafine Mg powder and Al powder increases the contact area between the active metal and polytetrafluoroethylene, thereby enhancing the reaction activity. The grinding of metal crystals produces new shuttles, angles and surfaces, making the atomic coordination number at the interface lower than its saturation value, resulting in the atomic bonding force being smaller than the internal molecules, further enhancing the reaction activity. In addition, grinding Mg powder and Al powder together, the synergistic enhancement of the two helps the ignition and durability of fireworks propellants.

[0019] (2) The present invention modifies polytetrafluoroethylene to enhance the adhesion of the fireworks propellant system. Boric acid and silane coupling agents are used to modify polytetrafluoroethylene so that the surface of polytetrafluoroethylene has both boron-containing and amino-containing groups. The boron-containing groups can provide empty orbitals to form coordination bonds with the fluorine atoms in polytetrafluoroethylene that provide electron pairs. On the one hand, they form coordination bonds with polytetrafluoroethylene, and on the other hand, they form coordination bonds with the active metal modified by the binder, which can significantly improve the adhesion strength of the fireworks propellant system.

[0020] (3) Boron powder is difficult to add in large quantities to propellants due to its large specific surface area and irregular shape, which is not conducive to adjusting the combustion performance of the composite energetic system. In addition, the B 2 O 3 The oxide layer leads to low ignition and combustion reactivity. The boron powder modified by the organic fluoropolymer PVDF in the present invention has good compatibility with the PTFE-based propellant system, can effectively promote the combustion of the propellant system in an oxidizing environment, and help release energy. At the same time, the HF generated by the decomposition of PVDF during combustion can react with B 2 O 3 The reaction destroys the oxide layer on the surface of the boron powder, which significantly improves the oxidation performance of the boron powder and the combustion performance of the propellant system.

[0021] (4) The present invention uses a thermite type high explosive heat additive, which has good compatibility with the fireworks propellant system with active metals and polytetrafluoroethylene as the main components, and is conducive to improving the explosive heat of the propellant. In addition, the present invention uses a flammable polymer material as a binder, which not only makes the obtained product have good bonding strength, but also can effectively enhance the ignition performance of the product. DETAILED DESCRIPTION

[0022] In order to have a clearer understanding of the technical features of the present invention, the technical solution of the present invention is now described in detail below, but it should not be construed as limiting the applicable scope of the present invention.

[0023] Example 1

[0024] (1) drying coarse Al powder and coarse Mg powder, mixing them in a mass ratio of 2.0, and grinding them into micron-sized mixed metal powders in a ball mill at a speed of 500 r / min;

[0025] (2) dissolving boric acid and a silane coupling agent in an ethanol solution at a mass ratio of 5.0, adding polytetrafluoroethylene, stirring thoroughly, heating to 80° C., reacting for 1 h, filtering, and drying to obtain modified polytetrafluoroethylene;

[0026] (3) dissolving PVDF in DMF, adding micro-nano boron powder, maintaining it in an ultrasonic environment at 80° C. for 0.5 h, and then magnetically stirring it for 5 h to make the boron powder evenly dispersed, and obtaining PVDF-modified high-energy boron powder through filtering, washing, and drying;

[0027] (4) Add 5 parts of adhesive polyester to 30 parts of the metal powder in step 1, and ball mill at a speed of 500 r / min for 0.5 h to obtain a modified metal powder. Then add 60 parts of modified polytetrafluoroethylene, 5 parts of high explosive thermal additive copper oxide, and 5 parts of modified high-energy boron powder. Place in a ball mill and mix at a speed of 500 r / min for 1 h to obtain a fireworks propellant product.

[0028] Example 2

[0029] (1) drying coarse Al powder and coarse Mg powder, mixing them in a mass ratio of 5.0, and grinding them into micron-sized mixed metal powders in a ball mill at a speed of 500 r / min;

[0030] (2) dissolving boric acid and silane coupling agent in an ethanol solution at a mass ratio of 10.0, adding polytetrafluoroethylene, stirring thoroughly and heating to 80° C. to react for 2 h, filtering and drying to obtain modified polytetrafluoroethylene;

[0031] (3) dissolving PVDF in DMF, adding micro-nano boron powder, maintaining in an ultrasonic environment at 100° C. for 1 hour, and then magnetically stirring for 10 hours to uniformly disperse the boron powder, and obtaining PVDF-modified high-energy boron powder through filtering, washing, and drying;

[0032] (4) Add 3 parts of adhesive polyester to 47 parts of the metal powder in step 1, and ball mill at a speed of 500 r / min for 1 hour to obtain a modified metal powder. Then add 45 parts of modified polytetrafluoroethylene, 5 parts of high explosive thermal additive copper oxide, and 10 parts of modified high-energy boron powder. Place in a ball mill and mix at a speed of 500 r / min for 2 hours to obtain a fireworks propellant product.

[0033] Example 3

[0034] (1) drying coarse Al powder and coarse Mg powder, mixing them in a mass ratio of 3.0, and grinding them into micron-sized mixed metal powders in a ball mill at a speed of 500 r / min;

[0035] (2) dissolving boric acid and silane coupling agent in an ethanol solution at a mass ratio of 8.0, adding polytetrafluoroethylene, stirring thoroughly and heating to 80° C. to react for 2 h, filtering and drying to obtain modified polytetrafluoroethylene;

[0036] (3) dissolving PVDF in DMF, adding micro-nano boron powder, maintaining in an ultrasonic environment at 100° C. for 1 hour, and then magnetically stirring for 8 hours to uniformly disperse the boron powder, and obtaining PVDF-modified high-energy boron powder through filtering, washing, and drying;

[0037] (4) Add 5 parts of adhesive polyurethane to 45 parts of the metal powder in step 1, and ball mill at a speed of 500 r / min for 1 hour to obtain modified metal powder, then add 40 parts of modified polytetrafluoroethylene, 10 parts of high explosive thermal additive copper oxide, and 8 parts of modified high-energy boron powder, place in a ball mill and mix at a speed of 500 r / min for 2 hours to obtain a fireworks propellant product.

[0038] Example 4

[0039] (1) drying coarse Al powder and coarse Mg powder, mixing them in a mass ratio of 3.0, and grinding them into micron-sized mixed metal powders in a ball mill at a speed of 500 r / min;

[0040] (2) dissolving boric acid and silane coupling agent in an ethanol solution at a mass ratio of 8.0, adding polytetrafluoroethylene, stirring thoroughly and heating to 80° C. to react for 2 h, filtering and drying to obtain modified polytetrafluoroethylene;

[0041] (3) dissolving PVDF in DMF, adding micro-nano boron powder, maintaining in an ultrasonic environment at 100° C. for 1 hour, and then magnetically stirring for 10 hours to uniformly disperse the boron powder, and obtaining PVDF-modified high-energy boron powder through filtering, washing, and drying;

[0042] (4) Add 5 parts of adhesive polyurethane to 45 parts of the metal powder in step 1, and ball mill at a speed of 500 r / min for 1 hour to obtain modified metal powder, then add 40 parts of modified polytetrafluoroethylene, 5 parts of high explosive thermal additive ferrosoferric oxide, 5 parts of high explosive thermal additive iron oxide, and 10 parts of modified high-energy boron powder, place in a ball mill and mix at a speed of 500 r / min for 2 hours to obtain a fireworks propellant product.

[0043] Example 5

[0044] (1) drying coarse Al powder and coarse Mg powder, mixing them in a mass ratio of 3.0, and grinding them into micron-sized mixed metal powders in a ball mill at a speed of 500 r / min;

[0045] (2) dissolving boric acid and silane coupling agent in an ethanol solution at a mass ratio of 7.0, adding polytetrafluoroethylene, stirring thoroughly and heating to 80° C. to react for 2 h, filtering and drying to obtain modified polytetrafluoroethylene;

[0046] (3) dissolving PVDF in DMF, adding micro-nano boron powder, maintaining in an ultrasonic environment at 100° C. for 1 hour, and then magnetically stirring for 10 hours to uniformly disperse the boron powder, and obtaining PVDF-modified high-energy boron powder through filtering, washing, and drying;

[0047] (4) Add 5 parts of adhesive polyurethane to 50 parts of the metal powder of the step, and ball mill at a speed of 500 r / min for 1 hour to obtain modified metal powder, then add 40 parts of modified polytetrafluoroethylene, 3 parts of high explosive thermal additive ferrosoferric oxide, 2 parts of high explosive thermal additive iron oxide, and 10 parts of modified high-energy boron powder, place in a ball mill and mix at a speed of 500 r / min for 2 hours to obtain a fireworks propellant product.

[0048] Table 1 Thermal decomposition parameters of fireworks propellants obtained in Examples 1 to 5

[0049]

[0050]

[0051] The thermal decomposition parameters of the fireworks propellants obtained from different material systems in Examples 1 to 5 are listed in Table 1. The active metals Mg and Al and high-energy boron powder have a good promoting effect on the thermal decomposition of the system and accelerate the thermal decomposition process of the fluoropolymer.

Claims

1. A method for preparing high-explosive thermal fireworks propellant based on a multi-interface enhanced structure, characterized in that: The following steps are involved: (1) drying coarse Al powder and coarse Mg powder and mixing them in a mass ratio of 2 to 5, grinding them into micron-sized powder in a ball mill at a speed of 500 r / min, adding a binder, and continuing to ball mill at a speed of 500 r / min for 0.5 to 1 h to obtain modified metal powder; (2) dissolving boric acid and a silane coupling agent in an ethanol solution at a mass ratio of 5 to 10, adding polytetrafluoroethylene, stirring thoroughly, heating to 80° C., reacting for 1 to 2 hours, filtering, and drying to obtain modified polytetrafluoroethylene; (3) dissolving polyvinylidene fluoride (PVDF) in dimethylformamide to prepare a solution with a mass concentration of 5% to 10%, adding micro-nano boron powder, maintaining it in an ultrasonic environment at 80 to 100° C. for 0.5 to 1 hour, and then magnetically stirring it for 5 to 10 hours to uniformly disperse the boron powder, and filtering, washing, and drying to obtain PVDF-modified high-energy boron powder; (4) Adding the modified polytetrafluoroethylene obtained in step (2) and the high-energy boron powder obtained in step (3) to the modified metal powder obtained in step (1), and then adding a high-explosive thermal additive, placing the mixture in a ball mill and mixing it at a speed of 500 r / min for 1 to 2 hours to obtain a high-explosive thermal fireworks propellant with a multi-interface enhanced structure.

2. The method for preparing high-explosive thermal fireworks propellant based on a multi-interface enhanced structure according to claim 1, characterized in that: The materials are configured according to the following weight proportions: 30-75 parts of modified polytetrafluoroethylene, 25-70 parts of modified metal powder, 5-10 parts of high explosive thermal additive, 5-10 parts of high energy boron powder, and 0.5-5 parts of binder.

3. The method for preparing high-explosive thermal fireworks propellant based on a multi-interface enhanced structure according to claim 1, characterized in that: The high explosive thermal additive is one or more combinations of copper oxide, iron oxide, ferroferric oxide and manganese dioxide.

4. The method for preparing high-explosive thermal fireworks propellant based on a multi-interface enhanced structure according to claim 1, characterized in that: The adhesive is one or more combinations of fluororubber, silicone rubber, fluorosilicone rubber, polyester and polyurethane.

5. The method for preparing high-explosive thermal fireworks propellant based on a multi-interface enhanced structure according to claim 1, characterized in that: The silane coupling agent is one or more combinations of trimethoxysilane, triethoxysilane, tri-n-propoxysilane and tri-n-butoxysilane.

6. The method for preparing high-explosive thermal fireworks propellant based on a multi-interface enhanced structure according to claim 1, characterized in that: The mass ratio of steel balls to materials in the ball milling process is 4:

1.

7. High-explosive thermal fireworks propellant based on a multi-interface enhanced structure, obtained according to the preparation method according to any one of claims 1 to 6.

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