Nanometric Aluminum in Explosives

Aluminum nanopowders, because of their larger surface area, can increase the burning rate of propellants. It has been suggested that the powders could also enhance the detonation properties of certain explosives. For these reasons, an experimental study was undertaken to compare the performance of nanometric and micrometric aluminum in various explosives. No enhancement of performance was found in plastic‐bonded explosives. In fact, a reduction of the detonation velocity was found in plastic‐bonded explosives that are based on an energetic binder system. No increase of the detonation velocity was found in mixtures of aluminum and either Composition B or Ammonium Nitrate Fuel Oil, but a small increase in the heat of detonation was measured. The mixture of TNT and nano‐aluminum demonstrated higher detonation velocities and heats of detonation. The increase was higher at small charge diameters. Nanometric aluminum was shown to reduce the critical diameter of such mixtures, and it is concluded that the nano‐aluminum reacts faster than regular micron‐size particles in TNT/Al compositions.     

Evaluation of Plastic Bonded Explosive (PBX) Formulations Based on RDX,Aluminum, and HTPB for Underwater Applications

Aluminized high explosives are known to give better underwater performance. All explosive formulations for underwater targets are filled into warheads and shells by casting method. TNT, a high explosive is used as casting medium due to its lower melting point. Plastic bonded explosives are fast replacing TNT‐based high explosive formulations for the reasons that they are more insensitive and low vulnerable explosives with better shelf life. Few aluminized plastic bonded explosive formulations based on RDX, aluminum, and HTPB have been processed, varying the aluminum content from 0 to 35% and evaluated underwater. The present paper discusses the experimental methodology adopted to evaluate the above formulations for their ballistic parameters, viz., peak over pressure and impulse. Explosion bulge tests have been conducted with each explosive formulation and extent of bulge in test plates is presented and compared with a standard underwater explosive, viz., HBX‐3.     

Effects of Aluminum Content on TNT Detonation and Aluminum Combustion using Electrical Conductivity Measurements

To improve the understanding how aluminum contributes in non‐ideal explosive mixtures, cast‐cured formulations were analyzed in a series of electrical conductivity experiments. Five types of TNT‐based aluminized explosives, with aluminum mass fractions from 0 % to 20 % were considered in this study. The electrical conductivity of the detonation products in aluminized explosives was measured using an improved conductivity measurement method. The conductivity measurement results show that the detonation process of TNT‐based aluminized explosives can be divided into two stages: the first stage is the detonation reaction of TNT, and the second stage is the combustion reaction of aluminum with the detonation products. In the first stage, the duration of the TNT detonation increases with increased aluminum content; examination of the peak conductivities of the explosives with various aluminum contents indicated that a higher aluminum content is associated with a lower peak conductivity. Additionally, the ignition time of Al in the second stage is also determined. This work not only presents a means for studying the detonation process of aluminized explosives at 0–2.21 μs, but it also verified the relationship between the aluminum content and electrical conductivity in detonation products.     

Comparison of underwater shock wave attenuation of a new insensitive high explosive with different explosives

A series of experiments is performed to compare underwater shock wave attenuation of a new insensitive and aluminized high explosive RS with TNT, JH14, and PBXN-111 explosives. A new model with a uniform expression is proposed to characterize the pressure-time histories of the explosives. Numerical results show that the new model is applicable for both aluminized explosives and ideal explosives. The correlation coefficients for fitted curves are verified by thousands of test data for different explosives, and the accuracy is above 0.99. The energy of the underwater shock wave generated by PBXN-111 and TNT characterized by the new model agrees well with available experimental results. In addition, the shock energy of the new insensitive and aluminized high explosive RS is higher than that of PBXN-11 by 13.4%. The general performance of underwater shock wave attenuation of the insensitive and aluminized high explosive RS is found to be better than that of TNT, JH14, and PBXN-111 explosives.     

RDX基铝薄膜炸药与铝粉炸药水下爆炸性能比较

为了减少铝粉炸药在生产过程中因铝粉对环境污染,降低铝粉炸药的撞击感度,提高含铝炸药的成型性及力学性能,将RDX用铝薄膜分层包裹得到新型的铝薄膜混合炸药。将铝薄膜混合炸药与铝粉炸药进行水下爆炸实验与爆速实验,得到两种炸药的爆速与压力时程曲线,经过分析计算得到两种炸药的压力峰值、冲量、冲击波能、气泡脉动周期与气泡能。结果表明：铝薄膜炸药药柱的轴向为RDX与铝薄膜独立贯通的结构,有利于降低混合炸药中添加物对基体炸药爆轰波传播的影响,从而使铝薄膜混合炸药的爆速高于铝粉炸药,导致铝薄膜炸药的冲击波损失系数高于铝粉炸药,使铝薄膜混合炸药的总能量、比气泡能与铝粉炸药相当情况下,其比冲击波能却降低了10.16%～10.33%,计算过程说明铝薄膜混合炸药的C-J压力计算公式具有合理性。     

Highly Thermal Stable TATB‐based Aluminized Explosives Realizing Optimized Balance between Thermal Stability and Detonation Performance

In this work, a series of TATB‐based aluminized explosives were formulated from 1, 3, 5‐triamino‐2, 4, 6‐trinitrobenzene (TATB), aluminum powders and polymeric binders. The thermal stability, heat of detonation, detonation velocity and pressure of the TATB based aluminized (TATB/Al) explosives were systematically investigated by cook‐off, constant temperature calorimeter, electrometric method and manganin piezo resistance gauge, respectively. The selected PBX‐3 (70 wt% TATB/25 wt% Al/5 wt% fluorine resin) achieved optimized balance between thermal stability and detonation performance, with the thermal runaway temperature around 583 K. The thermal ignition of TATB‐based aluminized explosive occurred at the edge of the cylinder according to the experimental and numerical simulations. Moreover, the critical thermal runaway temperature for PBX‐3 was calculated based on the Semenov's thermal explosion theory and the thermal decomposition kinetic parameters of the explosive, which was consistent with the experimental value.     

Dependences of the detonation velocity and propellant performance of metallized explosives on the charge density and additive content

The dependences of the detonation velocity and the propellant performance measured using the M-40 technique on the charge density for aluminized explosives with different mass fraction of Al were studied. The fractions of the energy of Al combustion utilized during the chemical reactions and during the acceleration of the flyer plate were estimated. Regression dependences of the detonation velocity and the propellant performance on the charge density were obtained. The effect of the addition of particulate Al, Ti, Zr, and W in an amount of 5–30% on the detonation velocity of high-density explosive charges based on plasticized RDX was investigated. It is found that the reduction in the detonation velocity with the addition of various metallic additives is determined by the longitudinal sound velocity of the additive, and not by its density. Simple formulas for calculating the detonation parameters of high-density metallized explosives were obtained.     

Energetic Characteristics of HMX‐Based Explosives Containing LiH

The high energy density compound octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) and the strong exothermic compound LiH represent an excellent principal explosive and an active fuel, respectively. Herein, the energetic characteristics of HMX‐based explosives are explored by adding LiH as fuel additive. The detonation parameters of HMX‐based explosives containing LiH were tested with free‐field explosion experiments and compared with those of traditional TNT, HMX, and aluminized explosives. The results show that the explosives exhibit higher energy and present preferable explosion effect when LiH is added as an explosive ingredient. The improvement of impulse is more than 32.8 % at 2 m. The shock wave peak overpressure increases by almost 40 % at a distance of 3 m from detonation center specially for the explosive containing both LiH and Al additives. Elemental H and Li are expected to release tremendous energy to effectively improve the explosives instant damage power, but the detonation duration is shorter than that of Al‐containing mixed explosives, which may limit the advantage over Al in the impulse. Li₂CO₃ powder is the solid product of HMX/LiH, which explains the LiH oxidation during the explosion. The exothermic processes in the formation are the reason for the increased energy of HMX/LiH explosives. These results can provide guidance to a potential energetic system formed by HMX and LiH.     

铝粉含量对梯铝炸药爆压和冲击波参数的影响

测试了以TNT为基不同含量含铝炸药的爆压和空中爆炸冲击波参数,通过分析铝粉对炸药爆压、空中爆炸参数和爆炸冲击波超压的影响,建立了爆压与铝氧比的关系曲线、5种TNT基含铝炸药的冲击波相似律方程和TNT/Al炸药的爆压与空中爆炸冲击波超压的关系式.结果表明,随着铝粉含量的增加,炸药的爆压呈指数衰减,近距离的冲击波超压也快速减小,但爆炸场温度和爆炸火球的直径及持续时间会增大.     

Analysis of Post Detonation Products of Different Explosive Charges

High explosive charges containing TNT, Comp. B, PBXN-106, TNT/TATB and the aluminium containing charges TNT/AN/Al, Comp. B/Al and a PBX high explosive with polyurethane binder, RDX, AP and Al have been initiated in a containment of 1.5 m³ in argon atmosphere. The gaseous and solid products were analyzed by mass spectrometry and other techniques. From the reaction products, the completeness of the Al reaction under different conditions was evaluated. The heat of detonation was calculated from the heat of formation of the products and the components of the explosive charges. The method described is suitable for studying the reaction behavior of components in composite explosives, especially of less sensitive high explosives.     

基于BKW状态方程的爆轰产物及参数的改进算法

为了降低爆轰产物及爆轰参数的求解难度,通过对质量守恒方程的基本可行解进行线性组合,得到了爆轰产物的平衡组成,并在此基础上进一步获得了爆轰参数。其主要实现方法为:由最小自由能原理对基本可行解进行筛选,然后根据最大放热原则确定初始解,并在最小自由能原则的引导下,由初始解和基本可行解的线性组合获得爆轰产物的平衡组成,以上操作步骤均由自编程序完成。应用支持向量机(SVM)线性模型对BKW状态方程参数进行了调整,并详细介绍了其主要步骤。使用此方法预测了PETN、CL-20和含铝炸药的爆轰产物及爆轰参数,经参数调整后,发现预测结果与实验值吻合良好;通过与单质炸药爆轰实验数据对比,发现调整BKW状态方程参数时,应当尽可能使用爆轰产物中气体含量相近的含能材料对SVM模型进行训练;若预测含铝炸药,应当使用铝氧比接近待测炸药的样品来训练SVM模型。     

Combustion heat of the Al/B powder and its application in metallized explosives in underwater explosions

An underwater explosion test is used to determine the detonation properties of metallized explosives containing aluminum and boron powders. An oxygen bomb calorimeter (PARR 6200 calorimeter, Parr Instrument Company, USA) is used to obtain the heat of combustion of the metal mixtures. As the content of boron powders is increased, the heat of combustion of the metal mixtures increases, and the combustion efficiency of boron decreases. The highest value of the combustion heat is 38.2181 MJ/kg, with the boron content of 40%. All metallized explosive compositions (RDX/Al/B/AP) have higher detonation energy (including higher shock wave energy and bubble energy) in water than the TNT charge. The highest total useful energy is 6.821 MJ/kg, with the boron content of 10%. It is 3.4% higher than the total energy of the RDX/Al/AP composition, and it is 2.1 times higher than the TNT equivalent.     

炸药爆炸能量的水中测试与分析

介绍了炸药爆炸能量的水中测试方法,对TNT和3种新设计的含铝炸药进行了水中爆炸的实验研究,比较了各炸药的爆炸性能.结果表明,发现冲击波峰值超压、冲量和冲击波能流密度等参数较好地符合爆炸相似律,得到了新配方各参数的爆炸相似律系数.计算了炸药的冲击波能和气泡能,并提出了计算爆炸总能量的方法.把实验测得的炸药的总能量与KHTR程序计算的爆热进行对比,二者符合得较好,说明了KHTR程序可用.     

Dependence of detonation velocity on charge density for foamed alumotol (Al/TNT) and TNT mixtures

Experimental data are presented on the dependence of the critical diameter and detonation velocity of cast and liquid porous TNT and TA-15 alumotol (Al/TNT) on charge density. The results of the detonation velocity measurements are compared with calculations. Based on this comparison, it is proposed that the reaction during detonation of alumotol is substantially heterogeneous and this is confirmed by plotting the detonation velocity as a function of density for model mixtures of TNT with various amounts of aluminum and an inert component. Translated fromFizika Goreniya i Vzryva, Vol. 34, No. 4, pp 88–93, July–August 1998.     

老化对TNT基熔铸炸药性能的影响

为了研究老化对炸药性能的影响,对自然贮存的3种熔铸炸药TNT／RDX、TNT／RDX／Al和 TNT／HMX／Al进行了加速老化试验。通过扫描电镜、真空安定性试验研究了老化前后3种炸药的微观形貌和安全性能,并测试了老化前后3种炸药的感度和爆速。结果表明,老化后炸药颜色变深,体积膨胀,质量变轻。样品的放气量小于2 mL／g ,热感度变化也较小。机械感度的变化与炸药组分和老化方式有关。TNT／RDX的爆速随着贮存时间的增加而降低,与整体加速老化情况一致,TNT／RDX／Al和 TNT／HMX／Al的爆热随贮存时间的增加变化趋势相反,说明两者老化机理可能不同。     

铝含量对RDX基含铝炸药爆压和爆速的影响

利用锰铜压力传感器和测时仪测量了不同铝含量的RDX基含铝炸药的爆压和爆速。拟合出爆压、爆速与铝含量的关系式,分析了铝含量对RDX基含铝炸药爆压、爆速的影响因素。结果表明,随着铝含量的增加,RDX基含铝炸药的爆压和爆速呈线性减小。计算了铝粉的质量分数在0~40%时所对应的PC-J=A(x)0ρD2中的A(x)值,拟合出A(x)值与铝含量的关系式,得到RDX基含铝炸药爆压与爆速之间的关系式。     

A Low‐Sensitivity Composition Based on FOX‐7

1,1‐Diamino‐2,2‐dinitroethene (DADNE, FOX‐7) is considered to be an explosive combining comparatively high performance and low sensitivity. In the present study, FOX‐7 has been evaluated as a possible replacement of RDX in TNT‐based melt‐cast compositions. A composition containing FOX‐7, TNT, Al and wax, and a method of preparing it were proposed. Its sensitivity to impact, friction, shock wave, jet impact, fast heating, and its thermal stability were tested. Some detonation parameters like the detonation pressure, velocity and heat were measured. Moreover, the Gurney velocity, the so‐called effective exponent of the expansion isentrope and the JWL equation of state of the detonation products were determined from the results of a cylinder test. The detonation characteristics were compared with that obtained for cast TNT.     

Underwater detonation performance of the aluminum film explosive

A new aluminized explosive is proposed, and the approach is to replace the aluminum powder in the traditional aluminized explosive with an aluminum film. The purpose is not only to improve mechanical properties and lower the impact sensitivity of traditional aluminized explosives, but also to reduce environmental pollution in the aluminum particle production process. The pressure-time curves of the aluminum film explosive and RDX are measured in underwater explosion experiments. The peak pressure, impulse, shock wave energy, and bubble energy are obtained by analyzing the curves. The results of the study indicate that the peak pressure of the aluminum film explosive is lower than that of RDX. However, the aluminum film explosive maintains a high pressure for a longer period of time. The large amount of energy is found to liberate by subsequent reactions of the Al film with the primary detonation products. The increase in the explosion energy of the aluminum film explosive is based mainly on the increase in the bubble energy.     

EAK基熔铸分子间炸药的能量和撞击感度

通过水下爆炸试验研究了RDX和HMX对EAK基熔铸分子间炸药水下能量的影响。结果表明,RDX和HMX对EAK基混合炸药起到明显的增能作用,但对含铝和非含铝体系有不同的作用效果。爆速和撞击感度测定表明,EAK—RDX混合炸药爆轰的理想化程度和稳定性及撞击感度随RDX含量的增加而增加。从能量和撞击感度两个方面综合考虑,RDX的较佳加入量应为20％～30％。     

Predicting Maximum Attainable Detonation Velocity of CHNOF and Aluminized Explosives

This paper describes a simple method to predict the detonation velocity of pure and mixed CHNOF explosives as well as aluminized explosives at their maximum nominal density as one of the most important detonation properties. The new correlation uses the contribution of some structural parameters to apply for a wide range of ideal and non‐ideal explosives. Aluminized explosives have non‐ideal behavior and the Chapman Jouguet detonation velocities significantly differ from those expected from existing thermodynamic computer codes for equilibrium and steady state calculations. With the presented method, there is no need to use any assumed detonation products, heat of formation and experimental data. Detonation velocities at maximum nominal density of explosives predicted by this procedure show good agreement with respect to experimental values. They are more reliable compared to the calculated results of well‐known empirical methods and computed outputs using BKWS equation of state for CHNOF and aluminized explosives.