Alkali Dinitramide Salts. Part 1: Synthesis and Characterization

Starting from commercially available ammonium dinitramide (ADN), which was dissolved either in water or in methanol, the sodium, potassium, rubidium and cesium dinitramide were synthesized in yields >70% by adding the corresponding alkali metal hydroxide. The basic equation for the reaction is the following:     

Spectroscopic Investigations of High‐Nitrogen Compounds for Near‐Infrared Illuminants

Alkaline metal salts are widely used in pyrotechnic formulations. For NIR pyrotechnics, potassium, and cesium nitrate are mainly used as oxidizers and infrared emitters. Herein, new NIR illuminant formulations were tested using several potassium and cesium salts of high‐nitrogen compounds such as tetrazole and triazole derivatives. The research of new formulations comprises the evaluation of sensitivity data and radiometric measurements of new formulations. It was further investigated whether the IR emission can be improved using different nitrogen releasing agents like aminotetrazole or diethylene triamine trinitrate (DETT) as hexamethylenetetramine replacements.     

An Overview on the Synthetic Routes and Properties of Ammonium Dinitramide (ADN) and other Dinitramide Salts

In recent years, there has been a considerable interest in the development of novel type of high performance propellants for use in solid rocket motors. Ammonium salt of dinitramidic acid NH₄N(NO₂)₂ (ADN) has attracted wide interest as a potentially useful energetic oxidizer for rocket propellants because of its clean and environment‐friendly exhaust products during burning. ADN contains one N (NO₂)₂ group and its synthesis requires new type of N‐nitration. The present paper reviews the general synthetic methods used for the synthesis of inorganic, organic and metal dinitramide salts and their properties, with a special emphasis on ammonium dinitramide. The salient features with reference to the extent of conversion and ease of separation of the products of the various synthetic methodologies are also addressed.     

二硝酰胺铵推进剂的能量特性

二硝 (基 )酰胺 (基 )铵 (ADN)是一种新型稳定的高能无机氧化剂 ,其单元推进剂的比冲为 2 0 0 3.2 Ns/kg,燃烧温度为 2 10 0 K,用ADN取代丁羟复合固体推进剂中的高氯酸铵 (AP) ,比冲可提高 10 4.5 Ns/kg,与 GAP组成的无烟推进剂比冲可达 2 6 0 7Ns/kg,由GAP/ADN/RDX组成的无烟推进剂 ,最高比冲为 2 6 30 Ns/kg.     

Evaluation of pyrotechnic smoke for anti-infrared and anti-laser roles

This paper describes the experimental setup for evaluation of pyrotechnic smoke compositions for anti-laser and anti-infrared roles using the continuous wave 10.6 μm CO₂ laser (4 watt) and presents the results for a few pyrotechnic smoke compositions. The particle sizes of the aerosol from pyrotechnic smoke compositions were also determined using Quartz crystal Microbalance - Cascade Impactor. Two smoke compositions containing hexachloroethane, anthracene/naphthalenee, potassium perchlorate and magnesium powder showed more than 97% attenuation of CO₂ laser, whereas a composition containing zinc oxide, aluminium, iron oxide along with hexachlorocthane was least effective.     

Evaluation of small scale n-heptane fire extinguishing efficacy by natural antioxidants based pyrotechnic compositions: An experimental study

The conventional pyrotechnic compositions (PCs) for firefighting application mostly consist of potassium nitrate, chlorate or perchlorate as oxidants and organic resin-like phenol-formaldehyde, melamine-formaldehyde, epoxy resin and polyurethanes are used as reducers. Unfortunately, there are also some potential disadvantages to the use of conventional compositions. These are related to high combustion temperature with the generation of heat and flame which may cause secondary fire chances and hazards associated with the use of organic resins. Exposure to phenol, melamine, epoxy resins and polyurethanes are considered as a life-threatening occupational hazard. Under the present study, new pyrotechnic compositions were prepared with the combination of natural antioxidants like ascorbic acid and gallic acid as reductant and mixture of potassium nitrate with potassium chlorate as oxidant. Fire extinguishing efficacies, calorific value, burn rate, the flame temperature of newly developed compositions was evaluated against potassium nitrate and phenol-formaldehyde resin-based conventional composition. Although both the new and conventional composition has shown good fire extinguishing efficacies, extinguishing 4.57 KW of small scale n-heptane pool fire in 3 to 4 seconds, these newly developed compositions showed 67% to 76% reduction in flame temperature. It was also found that these new compositions exhibit a faster burn rate and lower calorific value than the conventional composition. To understand the fire extinguishing mechanism by the discharged aerosol particulate, its physical and chemical characteristics were assessed by a series of techniques viz; HRXRD, SEM, FTIR, EDX.     

Pyrotechnic Flash Compositions

Flash compositions are used in fireworks as well as in pyrotechnic articles for technical purposes like report signals, battle simulation and practice devices, birdscaring ammunition and anti-riol-devices for instance. The special hazards in manufacture and use of these compositions result from the combination of both a high sensitivity and a strong explosive effect. The paper presents the safety characteristic data of some flash compositions (thermal and mechanical sensitivity and sensitivity to dectonation shock). In particular, the explosive strength of flash compositions is compared with soem values found for commercial explosives. Furthermore a comparison between a KClO₄/Al-mixture and TNT is made on the basis of shock wave measurements.     

Triaminoguanidine Dinitramide,TAGDN: Synthesis and Characterization

Two dinitramide salts with very high heat of formation have been identified, i.e. triaminoguanidine dinitramide (TAGDN) and guanylazide dinitramide (GADN). Thermochemical calculations showed that TAGDN‐propellants have a higher impetus than the corresponding GADN‐propellants at a given flame temperature. Due to the fact that a low flame temperature has to be prefered in a gun, TAGDN seems better suited as a component in gun propellants compared to GADN. TAGDN was thus synthesized, analyzed and characterized to determine some of its properties.     

Modification of Pyrotechnic formulations to aid recovery,recycling and demilitarization

Following the International Treaty held in London and Oslo in 1972 and its amendment in Paris in 1992 on banning the dumping of hazardous and toxic waste at sea, large stockpiles of unwanted munition are now awaiting disposal. Public awareness, environmental concern and legislation are preventing the disposal of this explosive waste by landfill, detonation and open pit burning. One solution to this dilemma is to recover the waste from the containers and recycle or dispose of the waste in an environmentally sensitive manner. Preliminary investigations have been conducted at Cranfield University in developing explosive compositions which can be safely recovered and recycled. Pyrotechnic compositions were prepared containing water soluble binders and pressed into pellets. Performance and sensitivity tests were carried out on the pellets. Inclusion of water soluble binders into pyrotechnic compositions did not have any detrimental effect on their performance. However, there was a 33% reduction in the Figure of Insensitiveness (F of I) in all cases except for the composition containing Dextrin. This had a similar F of I to the control pyrotechnic composition. The pellets containing Dextrin were immersed in water. 97% of the pyrotechnic components were successfully recovered from the water by filtration and recrystallization. The recovered components were recycled into new pyrotechnic compositions which performed just as well as the original composition. The results from this preliminary investigation show that recovery and recycling of pyrotechnic components is feasible for compositions containing water soluble binders.     

Binary Flash Compositions – A Theoretical and Practical Study

Flash compositions are a class of pyrotechnic effect compositions used in firecrackers as well as in military applications. They are widely recognized as perhaps the most dangerous pyrotechnic compositions. This study investigates binary flash compositions containing aluminum and (per)chlorate oxidizers. The sensitivities of binary flash compositions are measured, their explosive power is compared using micro‐scale ballistic mortar testing, and their detonation parameters are calculated using the EXPLO5 code.     

Combustion of Propellants with Ammonium Dinitramide

This paper reports a series of experiments involving ammonium dinitramide (ADN), a new energetic oxidizer of potential use in composite solid propellants. The experiments include (a) self‐deflagration of pressed pellets of ADN; (b) combustion of sandwiches with ADN laminae on both sides of a binder lamina that is either “pure” or filled with particulate oxidizer and other additives; and, (c) combustion of propellants with a bimodal oxidizer size distribution, wherein, combustion of coarse ADN and fine AP (ammonium perchlorate) and vice versa were used, in addition to mixtures of coarse ADN and AP, fine ADN and AP, and all‐ADN or all‐AP formulations.     

Laser Ignition of Pyrotechnics – Effects of Wavelength,Composition and Confinement

Ignition tests were carried out using three different laser systems and three different pyrotechnic compositions. Pyrotechnic materials investigated are: sulfur/charcoal/potassium nitrate based composition (gunpowder, GP), Shellac binder‐based boron/potassium nitrate composition (SR 44) and acaroid resin binder based magnesium/potassium nitrate composition (SR 371C). The laser sources were the multimode output from an Ar‐ion laser (λ=500 nm average), a high‐power commercial diode laser (λ=784 nm) and a small laser diode operating at around the same wavelength but controlled by a customized electronic circuitry. Lasers operating in the visible wavelength range provided more reproducible and quicker ignition than the infrared output from the diode lasers. It was found that unconfined gunpowder exhibits more reproducible ignition for both the visible and the infrared wavelengths compared to the other two compositions. The composition based on magnesium, SR 371C appeared to be very sensitive to laser intensity variations and gave erratic and therefore, irreproducible ignition delay times. The threshold laser energies to initiate reproducible ignition for the different wavelengths were measured and ignition maps were constructed. From these maps, the required laser power density for any value of the ignition delay time, i.e. laser energy density was determined. Tests were also conducted on gunpowder samples, partially confined in a modified pyrogen igniter capsule and a small laser diode. The diode was operated in single pulse mode using a current surge, which was much higher than the recommended value for CW operation. This provided ~1 W pulses at the end of a 1 mm diameter fiber optic cable and caused reproducible ignition in the semi‐confined pyrotechnic bed within the capsule. The threshold ignition energy under semi‐confined conditions was found to be substantially less than that required in the unconfined environment under similar experimental conditions.     

二硝酰胺盐溶解度的测定及拟合

为了研究适合二硝酰胺盐重结晶的溶剂,采用平衡法中的紫外分光光度法测试了3种二硝酰胺盐——脒基脲二硝酰胺盐(FOX-12)、二硝酰胺钾(KDN)和二硝酰胺铵(ADN)在不同溶剂中的溶解度;采用Apelblat方程与理想溶液模型拟合了溶解度数据;计算了二硝酰胺盐在不同溶剂中溶解时的热力学函数。结果表明,FOX-12在水中、KDN在乙醇水溶液中溶解度随温度变化明显,故水和乙醇水溶液可以分别作为FOX-12与KDN重结晶的溶剂;以乙醇作为溶剂时,由于存在氢键,故常温下ADN的溶解度大于10 g,而常温下FOX-12与KDN的溶解度小于1 g;Apelblat方程的拟合度(R 2)达到0.990以上,平均相对偏差(ARD)小于2%,表明Apelblat方程可以很好地关联溶解度数据。3种二硝酰胺盐在水、乙醇、异丙醇、乙醇水溶液、正丁醇中的溶解焓变和吉布斯自由能均为正值,表明溶解过程均为非自发的吸热过程。     

Improving the dyeing properties of textiles via utilization of redox systems. I. Dyeing of wool and wool/polyacrylic blend fabrics with acid dye

Dyeing of wool and wool/polyacrylic fabrics with an acid dye, namely, Kiton Scarlet 4 R, was carried out in absence or presence of different redox systems. The latter were based on sodium, potassium, or ammonium peroxodisulphate or potassium periodate as oxidant and glucose, sodium thiosulphate, potassium pyrosulphite or thiourea as reductant. Regardless of the redox system used, the colour strength was far greater in presence than in absence of the redox system. Except in case of potassium periodate/glucose redox system, increasing the oxidant concentration up to 0.03 mol/l caused significant enhancement in colour strength. The same was observed upon increasing the temperature from 30 to 60°C as well as the time from 10 to 40 minutes. It is postulated that presence of the redox system alters the mode of dye attachment to the substrate. Association of the dye with the substrate, wool in particular, seems to involve covalent bonding beside the usual salt-linkage. Hence the approach presented is advantageous in producing dyeings with much higher colour strength and dye fixation at relatively low temperature.     

Improved Mixing,Granulation and Drying of Highly Energetic Pyromixtures

A safer and more efficient method of mixing, granulating and drying (MIGRAD) highly energetic (UN 1.1) pyrotechnic composition will be reported. The process uses a MIGRAD mixer/granulator that was tailored to mix, granulate and dry a pyrotechnic material (20-40 lb) within a single mixing chamber. Features of the process include remote loading and unloading, reduced solvent, shortened mixing cycle (40 min), infinitely variable speed control of mixing and granulating impellers, built-in state-of-the-art fire detection/suppression (UV-50 ms, IR-10 ms), explosion venting, heated-chamber, vacuum drying, remote/programmable controls, and remote mixer cleanup using energy of the mixer. The mixing process will be evaluated for preparation of some 24 pyrotechnic compositions for five Arsenals/Ammo Loading Plants. Hazards Classification Safety Data Sheets were prepared for the 24 pyrotechnic compositions and will be reported along with resultant physical properties of the completed compositions.     

Thermochemical Calculations for Potassium Ferrate(VI), K2FeO4, as a Green Oxidizer in Pyrotechnic Formulations

This paper documents the first‐time assessment of a novel oxidizer, potassium ferrate(VI), as an alternative to perchlorate and hazardous metal‐containing oxidizers in energetic formulations, using thermochemical calculations. Calculations were performed for several different types of pyrotechnic formulations using the NASA Chemical Equilibria with Applications (NASA‐CEA) program. Formulations used in devices including smokes, illuminants, signals, igniters, delays, and flashes were evaluated to determine the feasibility of using potassium ferrate(VI) as an alternative oxidizer. The calculated adiabatic flame temperatures and equilibrium combustion products for the proposed formulations were compared to those of common baseline formulations for different pyrotechnic applications to determine the likelihood of functional success of potassium ferrate(VI)‐based formulations. Based on these initial data, it is highly probable that formulations incorporating potassium ferrate(VI) will result in reactive compositions for a variety of pyrotechnic applications. This material could address environmental concerns about perchlorate and heavy metal contamination by offering an environmentally‐friendly alternative oxidizer.     

Characterization of ADN and ADN‐Based Propellants

Ammonium dinitramide (ADN), NH₄N(NO₂)₂ is being considered as one of the potential new energetic oxidizers for composite propellants. In this study, ADN crystals, prills and two ADN‐based propellants having different relative amounts of ingredients were characterized. The concentration of the crystals and the prills samples was determined using ion chromatography. The thermal behavior of the crystals, prills and propellants was studied using DSC, simultaneous TG‐DTA‐FTIR‐MS, ARC (accelerating rate calorimeter), HFC (heat flux calorimeter) and INC (isothermal nanocalorimeter). Decomposition of ADN was observed from all of the samples at temperatures above the melting point of ADN (~ 92 °C). Formation of N₂O, NO₂, H₂O, CO₂, CO, N₂ and NO was detected during the ADN decomposition. The thermal stability of the ADN samples at temperatures below the melting point of ADN was studied. Early solid decomposition of ADN, which generates N₂O and H₂O, was observed at 60 °C. Electrostatic discharge (ESD) and impact sensitivity of the ADN samples were determined. The crystals and prills are sensitive to impact, while the two propellants are relatively less ESD and impact sensitive.     

Radiative Ignition of Pyrotechnics: Effect of Wavelength on Ignition Threshold

Using a broadband Xenon lamp and a high power laser diode, the ignition of several pyrotechnic compositions was evaluated using ultraviolet(UV), visible and infrared(IR) radiation. At irradiance levels of 4.9 W/cm² none of the compositions were ignited using UV radiation but SR112, B/Fe₂O₃ and gunpowder showed reactions to visible radiation at irradiance levels as low as 8.1 W/cm². Most of the compositions were ignited with IR radiation but Mg/NaNO₃ and SR 112 could not be ignited at irradiance levels of up to 300 W/cm². It is proposed that the difference in the response of the compositions was not directly related to the radiation absorption characteristics of the compositions; but was dependant on many physical, chemical and optical characteristics of the pyrotechnic powders. Increasing the irradiance reduces the time to ignition for most compositions.     

二硝酰胺钾的合成、晶体结构及性能

以N-脒基脲二硝酰胺盐(GUDN)和氢氧化钾为原料合成了二硝酰胺钾(KDN),用元素分析、傅里叶红外光谱对其结构进行了表征。培养了KDN的单晶,并通过X射线单晶衍射仪测定了其晶体结构。采用差示扫描量热分析仪(DSC)研究了KDN的热分解行为,并测试了其感度。结果表明,KDN晶体属于单斜晶系,P2(1)/n空间群,晶胞参数为:a=0.661 0(11)nm,b=0.927 2(15)nm,c=0.719 4(12)nm,β=97.568(3)°,V=0.437 1(12)nm~3;Z=4;Dc=2.236g/cm~3;F(000)=288。KDN的熔点为128℃,撞击感度大于50cm,摩擦感度为0,静电感度为142.53mJ,感度低于RDX,是一种钝感的二硝酰胺类含能材料。     

Ion Chromatographic Analysis of Ammonium Dinitramide–Oxidizer for Propellant and Pyrotechnic Applications

Analysis of ammonium dinitramide (ADN), the advance rocket propellant oxidizer, in pure form as well as in mixtures was carried out by ion chromatography (IC). The purity of ammonium dinitramide was directly determined by estimating the dinitramide ions and indirectly by estimating the impurities. Both methods gave results comparable with those determined by Differential Scanning Calorimetry and UV spectroscopy. The chemical composition of ADN in mixtures containing nitrate, chromate, chlorate, perchlorate, and thiocyanate ions was quantitatively estimated in the same solution without any interferences or prior separation of analyte ions. The newly developed ion chromatographic methods for the analysis of ADN are simple and fast with good accuracy and precision when compared to other analytical techniques. The IC methods are found to be highly suitable for quality control analysis of ADN containing compositions and for the online process monitoring of the formation of ADN in the reaction mixture.