Bi‐Spectral IRCM‐Flare Formulations based on Tetrazole‐Derivatives

The spectral performance, sensitiveness to ignition stimuli and burning rate of bi‐spectral flare formulations based on tetrazole containing fuels, 5‐phenyl‐1H‐tetrazole, 5,5′‐(1,4‐phenylene)bis(1H‐tetrazole) and 5‐(4‐nitro‐phenyl)‐1H‐tetrazole, utilizing potassium perchlorate as the oxidizer, are reported. The formulation based on 5‐(4‐nitro‐phenyl)‐1H‐tetrazole yielded the highest spectral efficiency in the β‐band (44.1 J g⁻¹ sr⁻¹). The formulation based on 5‐phenyl‐1H‐tetrazole gave the highest color ratio (θ_β/α=6.8) and was the least sensitive.     

火工品买卖方风险研究

应用贝叶斯方法研究了火工品买卖方风险问题，在先验分布和历史数据下，给出了买卖风险的计算公式。在一定的可靠度和风险要求下，确定了产品对应于各种失败数的试验量。     

Preheating Sensitization of a TATB Composition Part one: Chemical Evolution

We analyze the evolution of the sensitivity of a TATB composition after thermal cycles at elevated temperatures. Sensitization due to thermal cycles is of variable magnitude depending on the kind of the second stimulus (mechanical or thermal). In order to investigate the possible mechanisms which govern these phenomena, we perform an extensive study of the evolution of the chemistry and microstructure of our composition and we determine the sensitivity of our explosive to various stimuli after various temperature/duration cycles. This first paper is devoted to the study of TATB chemical evolutions. We present the results obtained for explosive decomposition, furazan generation, gas analyses and solid residue characterization.     

冲击载荷作用下火工分离保护装置的建模与分析

为了模拟空间火工分离保护装置冲击载荷下的动力学特性,首先,建立了该保护装置的简化模型,计算得到火工分离体的初速度,推导了装置的冲击变形和变形能公式;保护装置分别采用2A12、TC4、蜂窝夹层材料,建立三种材料的多线性本构模型,采用显式动力学求解步分析其冲击响应特性,分析可知,蜂窝夹层材料具有最佳的能量吸收特性,2A12的能量吸收特性介于蜂窝夹层材料和TC4之间,其塑性变形量适中;应变能释放和冲击碰撞的耦合分析可知,应变能占比小,体现为振荡衰减的过程,结构的冲击响应特性主要由碰撞冲击导致;试验表明,该火工分离保护装置的瞬态动力学过程与分析一致,局部最大应力为302MPa,冲击响应谱最大值为3242g,满足有效载荷的可靠解锁分离要求。     

2006–2008 Annual Review on Aerial Infrared Decoy Flares

The most recent progress in the field of advanced aerial infrared decoy flare technology is documented. 71 references from the public domain are given. For the last review please see Ref. [2].     

Heat Flux Measurement from Bulk Magnesium/Teflon/Viton (MTV) Flare Composition Combustion

Radiant heat output has been measured from an MTV flare composition for masses between 0.2 and 36 kg. Around 30 % of the heat of reaction is lost as radiation. The maximum temperature at the surface of the fireball is estimated to be around 1800 K. The effect of distance on the received radiated heat dose is complex but, with large buoyant fireballs, the attenuation might be as small as the inverse of distance.     

Study of a Classical Strobe Composition

Many strobe compositions were discovered in the past but only a few have been studied and none of them were fully understood. This article aimed at introducing the ternary composition of ammonium perchlorate as oxidizer, magnalium as fuel, and barium sulfate as metal salt. Parameters that influence its performances are analyzed. First, the binary compositions ammonium perchlorate/magnesium and ammonium perchlorate/magnalium were studied to observe the differences in behavior by using magnalium instead of magnesium. Next, variations were applied to the ternary composition changing the fuel: oxidizer:metal salt ratio. Finally the effect of potassium dichromate was analyzed. It is often added to the composition because it is known to improve the regularity and sharpness of flashes. The burning behavior was recorded using a high speed camera, together with emission spectra using a Charged‐Coupled Device (CCD) camera coupled with a spectrometer and the temporal evolution of the intensity with a photodiode coupled with an oscilloscope. The results of the experiment give first insights into the physical and chemical mechanisms and give directions to the further study on strobe reactions.     

A Selection of Alkali and Alkaline Earth Metal Salts of 5,5′‐Bis(1‐hydroxytetrazole) in Pyrotechnic Compositions

The dilithium ( 1 ), disodium ( 2 ), dipotassium ( 3 ) and dicesium ( 4 ) salt as well as the calcium ( 5 ), strontium ( 6 ) and barium ( 7 ) salt of 5,5′‐bis(1‐hydroxytetrazole) were prepared and characterized including NMR‐, IR‐ and Raman spectroscopy, mass spectrometry, elemental analysis and differential scanning calorimetry. The crystal structures of 1 , 2 and 4 – 6 were additionally determined by single‐crystal X‐ray diffraction. The sensitivities of the salts towards impact, friction and electrostatic discharge were determined by means of BAM (Bundesanstalt für Materialforschung‐ und prüfung) methods. The potential use of 1 , 6 and 7 as coloring agents in pyrotechnical mixtures as well as the utilization of 3 and 4 as additives in near infrared (NIR) emitting pyrotechnical formulations was examined.     

Preheating Sensitization of a TATB Composition Part Three: Sensitization for Various Stimuli,Interpretation and Conclusions

Preheating induced sensitization has been commonly studied in the frame of SDT but a complete analysis in terms of pyrotechnic safety needs to take into account other kinds of stimuli like “moderate” mechanical ones (crushing, drops…︁), new thermal fluxes or combined insults. We present the results of connected studies and propose sensitization mechanisms based on these data and on previous chemical and microstructure characterizations.     

Parameters Influencing the Pyrotechnic Reaction

Phenomena (reaction effects) such as varied light emissions, sound, varied burning rates, varied heats of reaction and reaction products occur during the reaction of inorganic redox systems used for pyrotechnics. The peculiarity of these redox reactions is, that they take place as solid‐solid, solid‐liquid or solid‐gaseous state reactions. In opposite the theoretical redox reaction normally postulated in inorganic chemistry takes place in a solvent. By variation of different parameters as for example the reducing agent, the oxidizer, the oxygen balance and the particle size, it is possible to create the above‐mentioned effects in a wide range.