高氯酸铵比表面积对推进剂热稳定性的影响

研究了高氯酸铵（ＡＰ）比表面积对推进剂热稳定性的影响。ＡＰ比表面积的增大会导致推进剂初始分解温度、高低温热分解峰温和高低温下分解反应活化能的降低，但分解反应速度常数随ＡＰ比表面积的增大而增大。键合剂可以改善推进剂的热稳定性。     

Nano‐Computed Tomographic Measurements of Partially Decomposed Ammonium Perchlorate Particles

High performance solid rocket motors typically contain ammonium perchlorate (AP) particles as the oxidizer. Ammonium perchlorate provides good performance, but thermal decomposition leads to safety concerns for handling and storing solid propellant. Computed tomography is shown to allow for visualization of the AP decomposition process, providing in‐situ, quantitative data. The current work demonstrates the use of nano‐computed tomography (nano‐CT) scanning to elucidate aspects of AP decomposition by studying partially decomposed 400 μm diameter AP particles after isothermal heating at 200 °C. Data provides insight into shape and location of the pores. Analysis shows that the porosity developed within the particle begins approximately 15 μm below the particle surface and moves inward as well as outward towards the surface as the heating time increases. No substantial heating time dependence was observed on the pore size distribution. The size and location distributions of decomposition sites forming below the AP particle surface were quantified for the first time. Comparisons to previous work are discussed.     

Effect of Zn Powders on the Thermal Decomposition of Ammonium Perchlorate

In this paper, the catalytic effect of Zn nanopowders on thermal decomposition of ammonium perchlorate (AP) as well as those of Zn micropowders has been investigated using differential thermal analysis (DTA). The results show that both nanometer and micrometer Zn powders show similar excellent catalytic effect on the decomposition of AP, while the total heat releases of AP added by Zn nanopowders are generally higher than those of AP added by Zn micropowders. In addition, an attempt has been made to explain the observed results with the help of theoretical considerations and data generated during this work.     

Experimental Investigation on the Heterogeneous Kinetic Process of the Low Thermal Decomposition of Ammonium Perchlorate Particles

The thermal decomposition of ammonium perchlorate has been extensively studied in the past. Nevertheless, the various results published illustrate, on the one hand, significant differences regarding the influence of different parameters on the decomposition and on the other hand, a lack of useful quantitative laws to predict the thermal behaviour of this crystal under a range of conditions (temperature, duration of exposure, presence of confinement).     

Nanocrystalline Transition Metal Oxides as Catalysts in the Thermal Decomposition of Ammonium Perchlorate

Nanocrystalline transition metal oxides (NTMOs) have been successfully prepared by three different methods: novel quick precipitation method (Cr₂O₃ and Fe₂O₃); surfactant mediated method (CuO), and reduction of metal complexes with hydrazine as reducing agent (Mn₂O₃). The nano particles have been characterized by X‐ray diffraction (XRD) which shows an average particle diameter of 35–54 nm. Their catalytic activity was measured in the thermal decomposition of ammonium perchlorate (AP). AP decomposition undergoes a two step process where the addition of metal oxide nanocrystals led to a shifting of the high temperature decomposition peak toward lower temperature. The kinetics of the thermal decomposition of AP and catalyzed AP has also been evaluated using model fitting and isoconversional method.     

Reducing Agglomeration of Ammonium Perchlorate Using Activated Charcoal

Ammonium perchlorate is the most widely employed oxidizer for composite solid propellants. When exposed to atmosphere, it absorbs moisture and agglomerates. It is usually vacuum dried in order to avoid this agglomeration. When ammonium perchlorate that has been exposed to atmosphere for a certain period of time, is used in making a composite solid propellant, the burning rate is different because of the change in particle size distribution due to its agglomeration. This change in burning rate will change the thrust‐time profile from that of what it is designed for. As one goes to a finer ammonium perchlorate particle size this problem becomes more evident. Experimental studies aimed at reducing the agglomeration of ammonium perchlorate by coating it with activated charcoal. Ammonium perchlorate coated with 1 % activated charcoal showed almost no agglomeration, even when the particle size of ammonium perchlorate is approx. 1 μm. The burning rates also remained unchanged when ammonium perchlorate coated with 1 % activated charcoal was employed in propellant composition, after it has been exposed to the atmosphere for a period of 1 h.     

Taguchi Optimization of Solvent-Antisolvent Crystallization to Prepare Ammonium Perchlorate Particles

The sphericity and size of ammonium perchlorate (AP) particles significantly influence the properties of composite propellants. As the AP particles become more spherical, the accumulation coefficient increases, the viscosity during casting decreases, and the particle loading and burning rate increase. Hence, the production of micronized AP particles with an average size between 1 and 20 μm is important to increase the loading percentage of AP in the composite propellant. Here, the Taguchi experimental design was used to optimize the solvent-antisolvent crystallization (SAC) process for the preparation of micronized AP particles with higher sphericity. SAC parameters such as the type of antisolvent, the solvent-to-antisolvent ratio, the antisolvent temperature, the stirring speed, and the retention time were investigated at four levels. The type of antisolvent and the solvent-to-antisolvent ratio were found to mainly contribute to improving the sphericity and size of the AP particles, respectively.     

Preparation of Cu/CNT Composite Particles and Catalytic Performance on Thermal Decomposition of Ammonium Perchlorate

Composite particles of carbon nanotubes (CNTs) and Cu were prepared by a chemical reduction method. Characterization of Cu/CNT composite particles was performed by TEM, SEM, FT‐IR, XRD, XPS, AAS, DTA and EDS. The results show that the surface of CNTs is covered by Cu particles, and that the diameter of Cu/CNT composite particles gets larger than that of CNTs. Furthermore, in the presence of Cu/CNT composite particles, the peak temperature of the high‐temperature decomposition of ammonium perchlorate (AP) decreased by 126.3 °C, and the peak of the low‐temperature decomposition disappeared. Compared with a sample of simply mixed Cu and CNTs, the peak temperature of the high‐temperature decomposition of AP‐Cu/CNTs composite particles decreased by 11.4 °C. Compared with Cu, the peak temperature of the high‐temperature decomposition of AP‐Cu/CNT composite particles decreased by 20.9 °C. This work shows that the catalytic performance of Cu on the thermal decomposition of AP can be improved by compounding with CNTs.     

Effects of Nanometer Ni,Cu, Al and NiCu Powders on the Thermal Decomposition of Ammonium Perchlorate

A study of the decomposition behaviour for Ammonium Perchlorate(AP) was carried out by differential thermal analysis and the two decomposition peaks were observed. The high temperature peak was found to shift to lower temperatures, but the corresponding shift in the low temperature peak was smaller due to the effect of nanometer metal powders. Results shows that Cu and NiCu nanopowders decreased both the high and low decomposition temperature, while Ni and Al nanopowders just decreased the high decomposition temperature and increased the low decomposition temperature. Metal micron‐sized powders show catalytic effects on the thermal decomposition of AP, but their effects are less than that of nanometer metal powders. With the increase in content, nanometer metal powders enhanced their catalytic effect on the high temperature decomposition of AP, however their effect was weakened on the low temperature decomposition.     

Kinetics of Thermal Decomposition of Ammonium Perchlorate with Nanocrystals of Binary Transition Metal Ferrites

This article was published in Early View with DOI 10.1002/prep.200800017 – what is wrong. It has appeared with the correct DOI 10.1002/prep.200900017 – in Propellants, Explosives, Pyrotechnics 2009 (34) issue 1/2009 on pp 78‐83.     

装药生产线高氯酸铵处理新工艺设计

对装药生产线高氯酸铵(AP)处理工艺进行研究.采用与现有工艺不同的射流式真空(负压)输送AP方式,经输送距离(垂直距离4.5m,水平距离1 m)的试验测定,AP1粒度d43变小约3μm.推进剂装药试验结果显示,球形AP d43变化10μm,推进剂燃速变化约0.1 mm/s.针对AP用量多,耗费人力大,提出了AP处理的优...     

Preparation of Magnesium‐based Hydrogen Storage Materials and Their Effect on the Thermal Decomposition of Ammonium Perchlorate

Magnesium‐based hydrogen storage materials (MgH₂, Mg₂NiH₄, and Mg₂Cu‐H) were prepared and their structures were determined by XRD and ICP investigations. Mg₂NiH₄ has a monoclinic crystal structure and Mg₂Cu‐H is a mixture of MgCu₂ and MgH₂. The effects of magnesium‐based hydrogen storage materials on the thermal decomposition of ammonium perchlorate (AP) were studied by thermal analysis (DSC). It was found that magnesium‐based hydrogen storage materials show obvious boosting effects on the thermal decomposition of AP. The thermal decomposition peak temperature of AP was decreased, while the heat release of the decomposition of AP was increased. It was revealed that the effects of magnesium‐based hydrogen storage materials on the decomposition of AP become stronger with increasing content. The influence mechanism on the thermal decomposition of AP is suggested as follows: hydrogen released from magnesium‐based hydrogen storage materials and Mg, Ni, or Cu react with the decomposed products of AP.     

Kinetics of Nano Titanium Dioxide Catalyzed Thermal Decomposition of Ammonium Nitrate and Ammonium Nitrate‐Based Composite Solid Propellant

This study deals with the influence of nanosized titanium dioxide (TiO₂) catalysts on the decomposition kinetics of ammonium nitrate (AN) and ammonium nitrate‐based composite solid propellant. TiO₂ nanocatalyst with an average particle size of 10 nm was synthesized by sol‐gel method using titanium alkoxide as precursor. Formation of nanostructured TiO₂ and presence of its anatase and brookite phases was confirmed by powder X‐ray diffraction (PXRD) and selected area diffraction (SAED) studies. Nano TiO₂ was further characterized by transmission electron microscopy (TEM), infrared (IR) spectroscopy, and thermogravimetry. The catalytic effect of TiO₂ nanocatalysts on the solid state thermal decomposition reaction of AN and nonaluminized HTPB/AN propellant was evaluated. To ascertain the effectiveness of the TiO₂ nanocatalyst, the thermal kinetic constants for the catalytic and non‐catalytic decomposition of AN and AN propellant samples were computed by using a nonlinear integral isoconversional method. Catalytic influence was evident from the lowering of activation energy for the catalyzed decomposition reactions. Apparently, the nanocatalysts provide Lewis acid and/or active metal sites, facilitating the removal of AN dissociation products NH₃ and HNO₃ and thereby enhance the rate of decomposition. The changes in the critical temperature of thermal explosion of AN and AN propellant samples due to the addition of TiO₂ nanocatalyst were also computed and the possible reasons for the changes are discussed.     

从复合固体推进剂中浸取高氯酸铵的动力学过程

为了探索以水为介质从复合固体推进剂中浸取高氯酸铵(AP)的动力学过程,分析了AP在水中的浸取过程,比较了不同浸取温度和试样厚度条件下AP的浸取平衡分离常数及其回收率,用SEM观察了浸取后的推进剂试样内部结构.结果表明,浸取速率常数随温度提高和推进剂试样厚度的减小而增大.浸取温度及试样厚度一定时,速率常数是定值,浸取速率...     

Effect of Nano‐Copper Oxide and Copper Chromite on the Thermal Decomposition of Ammonium Perchlorate

The catalytic effect on the thermal decomposition behavior of ammonium perchlorate (AP) of p‐type nano‐CuO and CuCr₂O₄ synthesized by an electrochemical method has been investigated using differential scanning calorimetry as a function of catalyst concentration. The nano‐copper chromite (CuCr₂O₄) showed best catalytic effects as compared to nano‐cupric oxide (CuO) in lowering the high temperature decomposition by 118 °C at 2 wt.‐%. High heat releases of 5.430 and 3.921 kJ g⁻¹ were observed in the presence of nano‐CuO and CuCr₂O₄, respectively. The kinetic parameters were evaluated using the Kissinger method. The decrease in the activation energy and the increase in the rate constant for both the oxides confirmed the enhancement in catalytic activity of AP. A mechanism based on an electron transfer process has also been proposed for AP in the presence of nano‐metal oxides.     

DB/AP系燃烧剂的设计与性能研究

设计了以双基(DB)推进剂、高氯酸铵(AP)为主要组分的燃烧剂,并加入金属可燃剂B、Mg、Al来调整燃烧剂的燃烧性能,采用全自动量热仪、数码摄像机、热电偶和TG-DSC测试了燃烧剂的燃烧热、燃速、火焰温度和热性能.结果表明,金属粉的加入可以提高燃烧剂的燃烧热、燃速和火焰温度,并可以改变其火焰结构;对于长距离、高沸点物质的引燃,3种金属粉中B粉的效果最佳,DB/AP/B的火焰温度可达1 070℃,火焰长度达25cm,其燃烧过程也更稳定,而DB/AP/Mg和DB/AP/Al在燃烧过程中产生大量的火星;AP和金属粉对DB推进剂的热分解没有影响.     

高氯酸铵复合物研究概况

对近年来高氯酸铵(AP)与推进剂燃烧剂、燃烧催化剂、高导热材料碳纳米管(CNTs)组成的复合物的热分解性能进行了总结,介绍了燃烧剂、催化剂和CNTs在含AP推进剂中的应用效果。结合当前含AP推进剂研究现状,认为AP复合处理是改善推进剂燃烧性能、能量性能和工艺性能的新型方法和有效途径,AP复合物具有良好的工程应用前景。     

Efficient Sensitivity Reducing and Hygroscopicity Preventing of Ultra‐Fine Ammonium Perchlorate for High Burning‐Rate Propellants

In this research, several inert materials, including some functional carbon materials, paraffin wax and the well‐known insensitive energetic material 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB) were selected to reduce the undesirable high sensitivity and hygroscopicity of ultra‐fine ammonium perchlorate (UF‐AP) via polymer modified coating. Structure, sensitivity, thermal and hygroscopicity performances of the UF‐AP based composites were systematically studied by scanning electron microscopy, sensitivity tests, thermal experiments, contact angle, and hygroscopicity analysis. The results showed that both the impact and friction sensitivity of UF‐AP can be remarkably reduced, respectively, with only a small amount of 2 % (in mass) desensitization agents. Meanwhile, improved thermal decomposition was gained, and the hygroscopicity can also be reduced to a large extent. Propellants containing 10 % coated UF‐AP in mass were processed and tested, the burning rate reached 45.7 mm s⁻¹, 50 % higher compared with that of normal AP, with remarkably reduced impact sensitivity from 11.5 J to 29.6 J and friction sensitivity from 76 % to 28 %.     

Conditions of Millisecond Laser Ignition and Thermostability for Ammonium Perchlorate/Aluminum Mixtures

The experimental investigations of laser‐induced ignition and heat action of ammonium perchlorate and aluminum powder mixtures are presented in this paper. A laser pulse with wavelength of 1.06 μm and duration of 3.5 ms was used. Powder mixtures of different dispersion were tested, namely, coarsely dispersed powders and nanopowders with average surface diameters of 80 and 0.25 μm, respectively. The values of ignition thresholds and delays of the mixtures activity in air were measured, and experimental results for different exposure conditions were obtained. The possible reasons of different sensitivity for the given mixtures to laser pulse and heat action are discussed.