阅读说明：本技术 一种高活性多层复合微球及其制备方法 (High-activity multilayer composite microsphere and preparation method thereof ) 是由 付晓梦 王伟 王芳 史钰 李伟 李春涛 徐国舒 赵晓丽 于 2020-04-28 设计创作，主要内容包括：本发明公开了一种高活性多层复合微球,按质量百分比由以下组分组成：金属粉20％～25％,热塑性弹性体5％～15％,工艺助剂5％～10％,氧化剂55％～65％,以上各组分的质量总和是100％；所述高活性多层复合微球由内而外依次为金属粉、热塑性弹性体和氧化剂；所述金属粉为纳米铝粉或纳米铝基合金粉；本发明还公开了该高活性多层复合微球的制备方法,将金属粉、工艺助剂和热塑性弹性体共融共混,制得含有金属粉的核层,再采用滚动造粒嵌入氧化剂形成壳层,得到金属粉/热塑性弹性体/氧化剂高活性多层复合微球；该方法工艺简单,易放大,无溶剂污染,能够满足固体推进剂配方研制及应用需求；通过该方法制得的高活性多层复合微球可以直接在发动机中进行固体推进剂装药。(The invention discloses a high-activity multilayer composite microsphere which comprises the following components in percentage by mass: 20-25% of metal powder, 5-15% of thermoplastic elastomer, 5-10% of process additive and 55-65% of oxidant, wherein the total mass of the components is 100%; the high-activity multilayer composite microspheres sequentially comprise metal powder, a thermoplastic elastomer and an oxidant from inside to outside; the metal powder is nano aluminum powder or nano aluminum-based alloy powder; the invention also discloses a preparation method of the high-activity multilayer composite microsphere, which comprises the steps of co-melting and blending metal powder, process aids and the thermoplastic elastomer to prepare a core layer containing the metal powder, and embedding an oxidant into the core layer by adopting rolling granulation to form a shell layer to obtain the metal powder/thermoplastic elastomer/oxidant high-activity multilayer composite microsphere; the method has simple process, easy amplification and no solvent pollution, and can meet the requirements of formula development and application of the solid propellant; the high-activity multilayer composite microspheres prepared by the method can be directly used for charging solid propellant in an engine.)

1. The high-activity multilayer composite microsphere is characterized by comprising the following components in percentage by mass: 20-25% of metal powder, 5-15% of thermoplastic elastomer, 5-10% of process additive and 55-65% of oxidant, wherein the total mass of the components is 100%; the high-activity multilayer composite microspheres sequentially comprise metal powder, a thermoplastic elastomer and an oxidant from inside to outside; the metal powder is nano aluminum powder or nano aluminum-based alloy powder.

2. The microsphere of claim 1, wherein the thermoplastic elastomer is one or more of ethylene-vinyl acetate copolymer, thermoplastic polyurethane and energetic thermoplastic elastomer.

3. The highly reactive multilayer composite microsphere according to claim 1, wherein said process aid is one or more of dioctyl sebacate, naphthenic oil and saturated fatty acid glyceride.

4. The highly reactive multilayer composite microsphere according to claim 1, wherein the oxidant is one or more of ammonium perchlorate, ammonium nitrate and modified ammonium nitrate.

5. A preparation method of high-activity multilayer composite microspheres is characterized by comprising the following steps:

step (1), processing a process auxiliary agent by adopting a rotary evaporator and reduced pressure distillation;

step (2), stirring and mixing the nano metal powder and the process auxiliary agent in a glove box for 15-30 min to form slurry A;

step (3), melting and mixing the thermoplastic elastomer and the slurry A at a certain temperature, and stirring to prepare slurry B;

step (4), pressurizing the prepared slurry B by a high-pressure peristaltic pump, then feeding the slurry B into a pressure type nozzle, dripping the sprayed molten liquid into a round pot granulator with oxidant powder inside, controlling the round pot to stably rotate, realizing oxidant attachment and sphericization of the multilayer composite microspheres, and obtaining the metal powder/thermoplastic elastomer/oxidant high-activity multilayer composite microspheres;

and (5) obtaining the high-activity multilayer composite microspheres with different particle sizes through a post-treatment process.

6. The method for preparing high-activity multilayer composite microspheres according to claim 5, wherein the vacuum degree of the reduced pressure distillation in the step (1) is-0.1 MPa to 0MPa, the temperature is 70 ℃ to 90 ℃, the time is 60min to 120min, and the rotating speed is 20rpm to 100 rpm.

7. The preparation method of the high-activity multilayer composite microsphere according to claim 5, wherein the certain temperature in the step (3) is 80-85 ℃ and the time is 15-30 min; the stirring is electric stirring, and the stirring speed is 40-50 rpm.

8. The preparation method of the high-activity multilayer composite microsphere according to claim 5, wherein the pumping rate in the step (4) is 0.5g/min to 20g/min, the nozzle temperature is 90 ℃ to 95 ℃, the internal and external pressure difference is 1MPa to 10MPa, the tray rotating speed is 5rpm to 20rpm, and the rotating time is 5min to 10 min.

9. The method for preparing high-activity multilayer composite microspheres according to claim 5, wherein the post-treatment process in the step (5) comprises one or more of sedimentation, drying and sieving.

10. The method for preparing high-activity multilayer composite microspheres according to claim 5, wherein the particle size of the high-activity multilayer composite microspheres obtained in the step (5) is in a range of 350 μm to 600 μm.

Technical Field

The invention relates to the technical field of solid propellant materials, in particular to a high-activity multilayer composite microsphere and a preparation method thereof.

Background

The energy is always the main line penetrating through the development process of the solid propellant technology, each large technical breakthrough of the solid propellant technology is accompanied by the improvement of the energy level, and meanwhile, the update of missile weaponry is promoted. From long-term development, the application of the novel energetic material is a key technology and a supporting technology for the energy performance leap of the solid propellant, and the continuous improvement of the application effect of the energetic material is a basic technology for the development of the high-performance solid propellant.

The nanoscale metal powder serving as a fuel is applied to the solid propellant, so that the detonation heat and density can be improved, the combustion efficiency is improved, and the combustion stability of the propellant is improved, but the nanoscale metal powder has the advantages of large specific surface area, high chemical reaction activity, sensitivity to the environment, high sensitivity, potential safety hazard and poor use effect in the solid propellant; meanwhile, in the combustion process of the solid propellant, because the combustion flame of the heterogeneous solid propellant has oxygen-rich and fuel-rich areas, unless internal turbulence exists, the oxygen-rich and fuel-rich areas can cause incomplete combustion and excessive combustion of the system, and both the conditions can cause the system to deviate from the total balanced composition, thereby causing large energy loss.

At present, researchers have formed core-shell particles from an oxidant and a reductant, and the core-shell particles have high specific surface area and short diffusion distance, so that the mass transfer rate between reactants is far higher than the reaction rate, and the chemical kinetics is enhanced; meanwhile, the precise control of the energy release rate and efficiency is realized by controlling the composition of the core-shell structure; but still has the problems of complex process and low energy utilization efficiency.

Disclosure of Invention

In view of the above problems, it is an object of the present invention to provide a high-activity multilayer composite microsphere; the core-shell particles are prepared by taking a thermoplastic elastomer as a medium, taking metal powder as a core and taking an oxidant as a shell, and the metal powder has the performances of high-energy release and low sensitivity by wrapping the metal powder; the high-activity multilayer composite microsphere can shorten the mass transmission distance in the reaction process, and can increase the contact point number of reactants per unit mass by regulating the stoichiometric ratio of the nano metal powder, the thermoplastic elastomer and the oxidant in the high-activity multilayer composite microsphere and the particle size of the composite microsphere, so that the high-activity multilayer composite microsphere has extremely high energy release rate, energy utilization efficiency and combustion (energy conversion) efficiency.

The second purpose of the invention is to provide the preparation method of the high-activity multilayer composite microsphere, which has the advantages of simple process, easy amplification and no solvent pollution, and can meet the requirements of formula development and application of the solid propellant; the high-activity multilayer composite microspheres prepared by the method can be directly used for charging solid propellant in an engine.

The first technical scheme adopted by the invention is as follows: the high-activity multilayer composite microsphere consists of the following components in percentage by mass: 20-25% of metal powder, 5-15% of thermoplastic elastomer, 5-10% of process additive and 55-65% of oxidant, wherein the total mass of the components is 100%; the high-activity multilayer composite microspheres sequentially comprise metal powder, a thermoplastic elastomer and an oxidant from inside to outside; the metal powder is nano aluminum powder or nano aluminum-based alloy powder.

Preferably, the thermoplastic elastomer is one or more of ethylene-vinyl acetate copolymer (EVA), Thermoplastic Polyurethane (TPU) and energy-containing thermoplastic elastomer (ETPE).

Preferably, the process aid is one or more of dioctyl sebacate, naphthenic oil and saturated fatty glyceride.

Preferably, the oxidant is one or more of ammonium perchlorate, ammonium nitrate and modified ammonium nitrate.

The second technical scheme adopted by the invention is as follows: the preparation method of the high-activity multilayer composite microsphere comprises the following steps:

step (1), processing a process auxiliary agent by adopting a rotary evaporator and reduced pressure distillation;

step (2), stirring and mixing the nano metal powder and the process auxiliary agent in a glove box for 15-30 min to form slurry A;

step (3), melting and mixing the thermoplastic elastomer and the slurry A at a certain temperature, and stirring to prepare slurry B;

step (4), pressurizing the prepared slurry B by a high-pressure peristaltic pump, then feeding the slurry B into a pressure type nozzle, dripping the sprayed molten liquid into a round pot granulator with oxidant powder inside, controlling the round pot to stably rotate, realizing oxidant attachment and sphericization of the multilayer composite microspheres, and obtaining the metal powder/thermoplastic elastomer/oxidant high-activity multilayer composite microspheres;

and (5) obtaining the high-activity multilayer composite microspheres with different particle sizes through a post-treatment process.

Preferably, the vacuum degree of the reduced pressure distillation in the step (1) is-0.1 MPa to 0MPa, the temperature is 70 ℃ to 90 ℃, the time is 60min to 120min, and the rotating speed is 20rpm to 100 rpm.

Preferably, the mixing temperature in the step (3) is 80-85 ℃, and the time is 15-30 min; the stirring is electric stirring, and the stirring speed is 40-50 rpm.

Preferably, in the step (4), the pumping speed is 0.5-20 g/min, the nozzle temperature is 90-95 ℃, the internal and external pressure difference is 1-10 MPa, the tray rotating speed is 5-20 rpm, and the rotating time is 5-10 min.

Preferably, the post-treatment process in step (5) comprises one or more of settling, drying and screening.

Preferably, the particle size of the high-activity multilayer composite microsphere obtained in the step (5) is in a range of 350-600 μm.

The beneficial effects of the above technical scheme are that:

(1) the invention leads the metal powder to have the performances of high energy release and low sensitivity by wrapping the metal powder.

(2) The high-activity multilayer composite microsphere can shorten the mass transmission distance in the reaction process, and can increase the contact point number of reactants per unit mass by regulating the stoichiometric ratio of the nano metal powder, the thermoplastic elastomer and the oxidant in the high-activity multilayer composite microsphere and the particle size of the composite microsphere, so that the high-activity multilayer composite microsphere has extremely high energy release rate, energy utilization efficiency and combustion (energy conversion) efficiency.

(3) The preparation process of the high-activity multilayer composite microspheres is simple, easy to amplify and free of solvent pollution, and can meet the requirements of formula development and application of the solid propellant.

(4) The high-activity multilayer composite microspheres can be directly used for charging solid propellant in an engine.

(5) The core-shell particles are prepared by taking the thermoplastic elastomer as a medium, taking the metal powder as a core and taking the oxidant as a shell, and have higher specific surface area and shorter diffusion distance, so that the mass transmission speed between reactants is far higher than the reaction speed, and the chemical kinetics is enhanced.

Drawings

FIG. 1 is a process flow diagram of a high activity multilayer composite microsphere of the present invention.

Detailed Description

The present invention is further illustrated by the following specific examples, it should be noted that, for those skilled in the art, variations and modifications can be made without departing from the principle of the present invention, and these should also be construed as falling within the scope of the present invention.

The invention relates to a high-activity multilayer composite microsphere which comprises the following components in percentage by mass: 20-25% of metal powder, 5-15% of thermoplastic elastomer, 5-10% of process additive and 55-65% of oxidant, wherein the total mass of the components is 100%; the high-activity multilayer composite microspheres sequentially comprise metal powder, a thermoplastic elastomer and an oxidant from inside to outside; the metal powder is nano aluminum powder or nano aluminum-based alloy powder.

The thermoplastic elastomer is one or more of ethylene-vinyl acetate copolymer (EVA), Thermoplastic Polyurethane (TPU) and energy-containing thermoplastic elastomer (ETPE).

The process auxiliary agent is one or more of dioctyl sebacate, naphthenic oil and saturated fatty glyceride.

The oxidant is one or more of ammonium perchlorate, ammonium nitrate and modified ammonium nitrate.

The preparation method of the high-activity multilayer composite microsphere comprises the following steps:

step (1), a rotary evaporator is adopted to carry out reduced pressure distillation treatment on the process auxiliary agent, and the process auxiliary agent is subjected to dehydration and purification; the reduced pressure distillation conditions are vacuum degree of-0.1 MPa-0 MPa, temperature of 70-90 ℃, time of 60-120 min and rotating speed of 20-100 rpm.

And (2) in order to uniformly mix the metal powder and the process auxiliary agent, manually stirring and mixing the nano metal powder and the process auxiliary agent in a glove box for 15-30 min to form slurry A.

Step (3), melting and mixing the plastic elastomer and the slurry A under a certain temperature condition, stirring to prepare uniform slurry B, and controlling the temperature to be 80-85 ℃ in order to melt and mix the thermoplastic elastomer conveniently; controlling the electric stirring time to be 15-30 min, wherein the stirring time is too short, the metal powder cannot be fully dispersed to form uniform slurry, and the time and energy are wasted when the stirring time is too long; the electric stirring speed is controlled to be 40rpm to 50rpm, the slurry can be splashed at an excessively high stirring speed, and the metal powder cannot be sufficiently dispersed at an excessively low stirring speed.

And (4) pressurizing the prepared slurry B by a high-pressure peristaltic pump, then feeding the slurry B into a pressure type nozzle, directly dropping the sprayed molten liquid drop into a round pot granulator with oxidant powder inside, controlling the round pot to stably rotate, realizing oxidant adhesion and sphericizing the multilayer composite microspheres, and obtaining the metal powder/thermoplastic elastomer/oxidant high-activity multilayer composite microspheres. Wherein the pumping rate is 0.5 g/min-20 g/min; controlling the temperature of the nozzle to be 90-95 ℃ to melt the slurry B, so that the viscosity is reduced, and liquid drops are conveniently formed; controlling the internal and external pressure difference to be 1-10 MPa, wherein the pressure difference is too small, the slurry cannot form liquid drops, and the pressure difference is too high, so that the formed liquid drops are too small, which is not beneficial to the later stage oxidant attachment and microsphere spheroidization; the rotating speed of the tray is controlled to be 5 rpm-20 rpm, and the excessively low or high rotating speed is not beneficial to the adhesion of the oxidant and the sphericization of the microspheres; the rotation time is controlled to be 5-10 min, the rotation time is too short, the sphericity of the microspheres is not high, the time and energy are wasted due to too high rotation time, and the cost is increased.

And (5) granulating the high-activity multilayer composite microspheres through one or more processes of settling, drying and screening to obtain the high-activity multilayer composite microspheres with the particle size range of 350-600 microns.