降低超细高氯酸铵感度的方法研究

为了降低超细高氯酸铵(AP)的机械感度,以十八烷胺为包覆剂,经气流粉碎工艺,制备了超细AP包覆粒子。通过对超细AP包覆粒子进行粒度分析、SEM分析、DSC分析及感度检测,研究了超细AP包覆粒子的包覆效果、热分解特性及感度特性。试验结果表明:超细AP包覆粒子,粒度为D50=5.8μm,表面有包覆层存在;超细AP包覆粒子的感度,与超细AP样品相比,当包覆剂质量分数为1%时,撞击感度降低31.2%,摩擦感度降低12.0%;当包覆剂质量分数为3%时,撞击感度降低34.5%,摩擦感度降低22.0%,且包覆剂用量越大,撞击感度和摩擦感度越低;但包覆剂对AP的热分解会产生一定的负面影响,质量分数应≤1%。     

包覆改性RDX及其在CMDB推进剂中的应用？

选用键合剂LBA-1和热塑性弹性体（ TPE）对RDX进行表面包覆改性,并应用于CMDB推进剂中。采用扫描电子显微镜（ SEM）表征了RDX包覆前后颗粒表面的变化情况,同时,分别测试了RDX包覆前后和制备的CMDB推进剂的摩擦感度和撞击感度,并且对含包覆RDX的CMDB推进剂的力学性能和燃烧性能进行了表征。结果表明,经包覆改性后降感效果均明显,其中键合剂包覆的RDX,摩擦感度降低了68％,对应的CMDB推进剂,摩擦感度降低了37.5％。两种材料包覆改性RDX对推进剂的力学性能均有明显的改善,其中经热塑性弹性体包覆改性后,RDX-CMDB推进剂的抗拉强度提高了4.72 MPa,延伸率提高了19.67％;对推进剂的燃烧性能有一定的影响。     

膨化高氯酸铵的制备及其性能研究

使用膨化剂在减压条件下制备出膨化高氯酸铵（AP）。利用扫描电镜、粒度分析仪、傅里叶红外光谱仪、比表面积仪、差示扫描量热仪、热失重分析仪及感度仪分别对膨化AP进行形貌分析和性能测试。结果表明:膨化AP颗粒表面具有沟壑,内部具有孔洞结构,粒径D₅₀=22.559 μm;与未膨化的原料AP相比,膨化AP低温分解温度提高16.0 ℃,高温分解温度提高6.7 ℃,分解热提高322.3 J/g;比表面积增大92.2%,吸湿性增大;极限撞击能为10 J,撞击感度提高。制备AP/HTPB(端羟基聚丁二烯)和膨化AP/HTPB复合推进剂并测定其燃速,膨化AP/HTPB复合推进剂燃速提高4.1%。     

F2604/AP复合物制备及性能研究

采用静电喷雾技术制备了以氟橡胶(F2604)为包覆材料的F2604/AP(高氯酸铵)复合物。通过对所制备的复合颗粒进行扫描电镜(SEM)、傅里叶变换红外光谱(FTIR)、差示扫描量热(DSC)及机械感度检测分析,研究超细AP复合物包覆效果、热分解特性及感度特性。结果表明,由静电喷雾技术所制备的复合含能材料颗粒尺寸小、分布均匀、包覆效果良好;与AP样品颗粒相比,AP复合含能材料样品颗粒的放热峰温度有大约70~80℃的延后,热分解温度有所提高,有利于其热稳定性;随着F2604含量的增加,F2604/AP复合颗粒的机械感度逐渐降低,F2604的添加可以有效降低AP的机械感度。     

不同粒度及包覆改性高氯酸铵的热分解性能和安全性能研究

采用扫描电子显微镜和X射线衍射仪对不同粒度及包覆改性高氯酸铵(AP)颗粒的分散性及晶相进行了表征,并通过差示扫描量热法和机械感度测试研究不同AP样品的热分解性能和安全性能。结果表明,随着AP粒度增加,颗粒分散性得到一定改善,相同粒度的包覆改性AP分散性优于普通AP;不同粒度及包覆改性AP的晶相均一致;AP粒度越小,其热分解性能越好,对于粒度相同的AP,包覆改性对其热分解性能影响不大;随着AP粒度增加,其撞击感度和摩擦感度均降低,平均粒径(d_(50))分别为1μm、3μm和6μm的AP其撞击感度和摩擦感度分别为96%、80%、64%和28%、28%、16%;包覆改性可以明显降低AP的感度,d_(50)为3μm的包覆改性AP与粒度相同的普通AP相比,撞击感度和摩擦感度分别降低了28%和16%。     

化学镀法制备纳米Cu/Al复合粉末

为了改善超细铝粉的表面易氧化问题和微米级铝粉对推进剂的热分解催化作用不明显现象,以对推进剂具有良好催化作用的纳米Cu包覆金属Al表面.采用化学镀铜法对微米级铝粉表面进行镀覆,制备出纳米Cu粒子在超细Al颗粒表面包覆完整的Al-Cu核壳式复合粉末,并利用正交实验优化镀液组分及镀覆工艺条件.利用XRD、SEM、EDX等仪器,对复合粉末的形貌、物相结构及表面成分进行分析,结果表明铝粉表面包覆一层致密的纳米铜层,这种纳米层是由粒度约为18.83nm的晶态析出的纳米铜组成.     

纳米黑索今研究进展

纳米黑索今（nano—RDX）具有燃速较高、撞击感度较低等优点,在高燃速、低特征信号推进剂中有广泛的应用前景。文章综述了国内外纳米黑索今制备、性能及应用研究进展,发现惰性气体热升华和湿润研磨工艺在制备纳米黑索今方面具有独特的优势。     

HMX降感技术研究进展

以HMX降感为主线,分别从改善HMX晶体品质、表面包覆和共结晶三方面综述了近年来国内外的研究进展。对各方法的特点、降感机理及效果进行了介绍,指出从微观结构角度对HMX进行改性,即选择钝感含能化合物与HMX共结晶,是降低HMX感度最本质有效的方法。以现有研究为基础,总结并提出了今后研究工作中应注意的一些问题和研究重点。     

高分子复合黏胶体系对CL-20包覆及性能的影响

为了降低CL-20的机械感度,选择聚丙烯酸酯橡胶（HyTemp）和聚氨酯（TPU）作为黏结剂,微晶蜡作为钝感剂,对CL-20晶体表面进行包覆,分别制备了CL-20/HyTemp/微晶蜡、CL-20/TPU/微晶蜡、CL-20/HyTemp复配TPU/微晶蜡3种样品。分别通过扫描电子显微镜（SEM）、X射线衍射仪（XRD）、X射线光电子能谱仪（XPS）、差示扫描量热仪（DSC）、机械感度仪来表征样品的表面包覆情况、晶体结构、热稳定性以及机械感度。结果显示:HyTemp、TPU和微晶蜡都能有效包覆CL-20;且3种样品中CL-20的晶型仍为ε型,未发生改变。与包覆前相比,3种样品中氮元素含量均有大幅度的降低,包覆程度较高。其中,高分子复合黏结剂（HyTemp复配TPU）包覆样品的表面更为紧凑密实。与原料CL-20相比,复合黏结剂包覆样品的表观活化能提高了164.45 kJ/mol,熵变和焓变也有较大提升,反应活性降低,热稳定性明显改善;临界载荷由原料CL-20的60 N提高到了288 N,撞击感度也比原料CL-20降低了3.6 J,降感效果显著。采用HyTemp复配TPU作为黏结剂包覆的样品综合性能最好。     

PVP对球形铝粉进行表面包覆改性的研究

为防止球形铝粉在空气中腐蚀变质,采用溶液聚合法,通过硅烷偶联剂KH-550对超细铝粉进行预处理,在引发剂偶氮二异丁晴的作用下,用聚乙烯吡咯烷酮(PVP)对球形铝粉进行表面改性,形成了PVP-Al复合粒子。利用扫描电镜、能谱以及红外光谱对改性前后的铝粉进行表征分析;利用光电子能谱对复合粒子的形成原理进行分析。结果表明:复合粒子为具有核-壳结构的球形粒子,致密的PVP壳层包覆铝粒子;复合粒子的沉降率及耐腐蚀性优于原料铝粉。     

纳米Cu对HTPB-AP推进剂性能的影响

为研究纳米铜Cu对丁羟推进剂性能的影响,制备了含纳米Cu的推进剂,作为比较,同时制备了含有纳米CuO的推进剂和空白推进剂试样。采用SEM和TG-DSC表征推进剂的形貌和热性能,采用靶线法测试推进剂的燃速,并拍摄推进剂的燃烧火焰。TG-DSC结果表明,纳米Cu和纳米CuO主要影响AP的高温热分解阶段,但是纳米CuO比纳米Cu对推进剂的热分解具有更好的催化作用。纳米Cu可使AP的终止热分解温度降低67.0 ℃,使推进剂的终止热分解温度降低24.7 ℃。燃速测试结果表明,纳米Cu和纳米CuO均可提高推进剂的燃速,但是纳米Cu对推进剂燃速的改善效果更显著。加入纳米Cu和纳米CuO后,推进剂在燃烧过程中均出现蓝色火焰。     

Crystal habit modification of ammonium perchlorate by ethylene glycol

Ammonium perchlorate (AP)-based composite propellant has been widely used as a solid propellant, but higher burning rates are in demand. We report that crystal-habit-modified AP is an effective oxidizer that increases the burning rates of propellants. The modified APs have a dendritic shape. However, dendritic AP is not convenient to mix and cast in an AP/binder slurry because of its high viscosity. We attempted to prepare a crystal-habit-modified AP with polygon or sphere form. The crystal habit of AP was modified by ethylene glycol such that the intensity of the lattice plane (2 1 0) of the modified AP was remarkably high. The shape was almost hexahedral, and the mean particle diameter was approximately 150 μm.     

Synthesis,characterisation and catalytic activity of cadmium cobaltite nanoparticles: part 87

In this paper, we report the synthesis of cadmium cobaltite nanoparticles (CCNs) and their characterisation by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). The particles are spherical in shape and the average particle size is of the order of 20–30 nm. Its catalytic activity was investigated through the thermal decomposition of ammonium perchlorate (AP), composite solid propellants (CSPs), 5-nitro-2,4-dihydro-3H-1,2,4-triazole-3-one (NTO) and 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) using thermogravimetry (TG), TG coupled with differential scanning calorimetry (TG-DSC) and ignition delay measurements. The kinetics of thermal decomposition of AP + CCNs has also been investigated using isoconversional and model-fitting approaches, which have been applied to data for isothermal TG decomposition. The burning rate of CSPs was considerably enhanced by these nanoparticles. The ignition delays and activation energies are found to decrease when CCNs were incorporated in the system. The addition of CCNs to AP led to a shifting of the high-temperature decomposition peak towards lower temperature. All these studies show enhancement in the rate of decomposition of AP, NTO, HMX and CSPs.     

Synthesis, characterization and catalytic activity of CdO nanocrystals

In this paper, we report the synthesis of nanocrystalline cadmium oxide (CdO) and its characterization by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Its catalytic activity was investigated on the thermal decomposition of 1,2,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX), ammonium perchlorate (AP), hydroxyl terminated polybutadiene (HTPB) and composite solid propellants (CSPs) using thermogravimetric analysis (TG), simultaneous thermogravimerty and differential scanning calorimetry (TG-DSC) and ignition delay measurements. Kinetics of thermal decomposition of AP + CdO has also been investigated using model free (isoconversional) and model-fitting approaches which have been applied to data for isothermal TG decomposition. All these studies show enhancement in the rate of decomposition of AP, HTPB and CSPs but no effect on HMX. The burning rate of CSPs has also been found to be increased with CdO nanocrystals.     

Development of a deterred propellant for a large caliber weapon system

There is a continuing need to increase the velocity and associated terminal performance of kinetic energy ammunition as tougher armor targets are encountered. Application of a deterrent, or burning rate reducer, into the surface of standard propellants, together with appropriate changes in geometry and loading density, has been suggested as a means of increasing velocity by as much as ten percent. The attainment of such a desirable performance gain is critically dependent on the deterrent's satisfying certain requirements: (1) chemical compatability with the base propellant, (2) sufficient penetration of the base propellant, (3) diffusion stability of the deterred region over an extended time, (4) ignitability of the deterred layer, (5) sufficient decrease in burning rate. Unfortunately, there exists only a minuscule data base on the way deterrents behave when applied to various base propellants. The deterred propellants used in small arms and anti-aircraft guns were developed by a cut-and-try technique, and the sort of data required for rational design of large caliber weapons systems, e.g. burning rates in the deterred region, is extremely scarce. Since we lack an appropriate data base we have used thermochemical calculations and burning rate estimates to identify promising deterrent/base propellant combinations. The burning rate estimates were based on empirical fits to available closed bomb and strand burner tests with small arms propellants. Several promising deterrent systems are presented, including five candidates which exhibit a decrease in burning rate with no decrease in propellant energy. On the basis of these theoretical predictions, an experimental deterrent coating and analysis study has been initiated at Radford Army Ammunition Plant.     

少烟PBT推进剂制备及性能研究

为获得少烟且高能量的复合固体推进剂，使用含能PBT黏合剂，制备了铝粉质量分数为5%的PBT叠氮三组元推进剂，研究了推进剂的能量、燃烧及力学性能。结果表明，推进剂在固体质量分数78%时能量和工艺性能最优，使用φ118标准发动机测试能量比冲达246.4 s；压强指数随燃速铜铬催化剂RC和增塑剂ATC用量的增加而降低；燃烧速度随RC和超细高氯酸铵AP用量的增加而升高；固化参数或键合剂用量增加后，推进剂抗拉强度升高、伸长率降低。制备的少烟叠氮配方综合性能良好，可供高性能少烟推进剂装药。     

超细镍粉的制备及还原生长机理研究

以联氨为还原剂,在硫酸镍水溶液中控制液相还原反应条件制备了超细镍粉,并讨论了超细镍粉的还原生长机理.通过实验分析了工艺参数对还原反应的影响,采用X射线衍射(XRD),扫描电镜(SEM),比表面积测定等分析手段对超细镍粉进行表征,结果表明:超细镍粉的形核和生长独立进行;温度、Ni2+浓度和pH值调控着溶液中镍离子的释放并...     

Initial fuel temperature effects on burning rate of pool fire

The influence of the initial fuel temperature on the burning behavior of n-heptane pool fire was experimentally studied at the State Key Laboratory of Fire Science (SKLFS) large test hall. Circular pool fires with diameters of 100mm, 141 mm, and 200 mm were considered with initial fuel temperatures ranging from 290 K to 363 K. Burning rate and temperature distributions in fuel and vessel wall were recorded during the combustion. The burning rate exhibited five typical stages: initial development, steady burning, transition, bulk boiling burning, and decay. The burning rate during the steady burning stage was observed to be relatively independent of the initial fuel temperature. In contrast, the burning rate of the bulk boiling burning stage increases with increased initial fuel temperature. It was also observed that increased initial fuel temperature decreases the duration of steady burning stage. When the initial temperature approaches the boiling point, the steady burning stage nearly disappears and the burning rate moves directly from the initial development stage to the transition stage. The fuel surface temperature increases to its boiling point at the steady burning stage, shortly after ignition, and the bulk liquid reaches boiling temperature at the bulk boiling burning stage. No distinguished cold zone is formed in the fuel bed. However, boiling zone is observed and the thickness increases to its maximum value when the bulk boiling phenomena occurs.