Vibration-induced decomposition of lead azide

The decomposition of lead azide under the influence of vibration is investigated. The kinetics of its decomposition is analyzed by a manometer technique, and the kinetic characteristics are calculated from the experimental data. Thermographically recorded data exhibit a significant change in the physicochemical properties of lead azide. The reaction products are identified by x-ray phase analysis. The influence of mechanical activation on the decomposition kinetics is ascertained.Samara. Translated from Fizika Goreniya i Vzryva, Vol. 29, No. 4, pp. 88–91, July–August, 1993.     

铝粉粒度对RDX热分解动力学的影响

采用DSC研究了10.7μm、2.6μm和40 nm铝粉对RDX热分解的影响.结果表明,微米铝粉对RDX的热分解基本没有影响;40 nm铝对RDX的一次分解和二次分解均有明显的促进作用;随着40 nm铝含量的增加,RDX的二次分解峰凸显出来并提前,峰形变得尖锐;当40 nm铝质量分数为30％时,二次分解峰掩盖一次分解峰...     

Vibration sensitivity of solid explosives

The vibration sensitivity of solid explosives has been studied and is found as a function of the explosive parameters and the type of roller devices used to model various deformation conditions. A method is proposed for determining the vibration sensitivity from the probability of explosions as a function of the vibration parameters, experimental data on the sensitivity of some explosives and on the stresses in specimens are given, and a mechanism of initiating an explosion under cyclical loads is considered.Samara State Technical University, Samara 443010. Translated from Fizika Goreniya i Vzyrva, No. 1, 97–103, January–February, 1995.     

Criteria for estimation of explosion hazard in producing and processing explosives under vibration

The methods and criteria of estimating explosion hazard in processing high explosives (HE) with the use of mechanical effects are analyzed. It is shown that there are no methods and criteria in processing HE using vibrational technology. A new method and a new criterion of estimating explosion hazard upon vibrational processing of HE are proposed. The criterion is calculated on the basis of experimental results concerning the sensitivity of HE to vibration and a comparison of the critical parameters of vibratory loads that cause explosion or significant decomposition of HE with the vibration parameters in processing HE on vibration devices. Examples of the calculation of the safety factor for RDX, TNT, and ammonite upon vibrational pressing and vibrational transportation are given. Translated fromFizika Goreniya i Vzryva, Vol. 36, No. 5, pp. 90–96, September–October, 2000.     

CL–20/RDX混合体系的热分解

用差示扫描量热法(DSC)研究了六硝基六氮杂异伍兹烷(HINW,CL–20)、黑索今(RDX)及CL–20/RDX混合体系的热分解行为,分别用Kissinger法和Ozawa法计算了热分解动力学参数。结果表明:RDX的存在,降低了CL–20的分解峰温;2种动力学计算结果相近,均显示出RDX的存在降低了CL–20表观活化能。     

RDX flame structure at atmospheric pressure

The chemical structure of an RDX flame at a pressure of 1 atm was studied using probing molecular beam mass spectrometry. The flame was found to contain RDX vapor, and its concentration profile was measured in a narrow zone adjacent to the burning surface. In addition to RDX vapor, ten more species were identified (H₂, H₂O, HCN, N₂, CO, CH₂O, NO, N₂O, CO₂ and NO₂), and their concentration profiles were measured. Two main chemical-reaction zones were found in the RDX flame. In the first, narrow, zone 0.15 mm wide adjacent to the burning surface, decomposition of RDX vapor and the reaction of NO₂, N₂O, and CH₂O with the formation of HCN and NO occur. In the second, wide, zone 0.85 mm wide, HCN is oxidized by NO to form the final combustion products. The composition of the final combustion products was analyzed from an energetic point of view. The measured composition of the products near the burning surface was used to determine the global reaction of RDX gasification at a pressure of 1 atm. Values of heat release in the condensed-phase calculated by the global gasification reaction and by the equation of heat balance on the burning surface (using data of microthermocouple measurements) were analyzed and compared. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 1, pp. 49–62, January–February, 2008.     

Decomposition of lead azide,pentaerythrite tetranitrate,and a laminate system composed of these substances under vibrational loading

Decomposition of lead azide (LA), pentaerythrite tetranitrate (PETN), and a laminate system composed of these substances under vibrational loading is considered. Sensitivity of these substances to impact and vibrations is determined. Sensitivity of the LA + PETN laminate system to vibrational loading, which is characterized by the degree of decomposition, is substantially higher than that of PETN, but lower than that of LA. Specific features of the mechanism of decomposition of these substances at moderate values of vibration parameters and temperatures of specimen heating are discussed. __________ Translated from Fizika Goreniya i Vzryva, Vol. 45, No. 1, pp. 73–79, January–February, 2009.     

惰性溶剂中黑索今的热分解机理

根据溶剂对 RDX热分解行为的不同影响可将溶剂分为活性和惰性两类。活性溶剂加速 RDX热分解 ,惰性溶剂对 RDX热分解速率无影响或因其粘度较大而降低了热分解速率。本文用布氏压力法研究了 RDX在惰性溶剂中热分解机理 ,补充了许多二级反应 ,借助这些二级反应用初始步断裂 N- NO2 键机理较好地解释了溶剂粘度对 RDX热分解速率的影响和 RDX在苯中浓度对放气量及反应中间产物亚硝基黑索今得率的影响。所提出的机理丰富、完善、发展了二元硝胺炸药热分解理论     

超重力辅助溶剂-反溶剂重结晶法制备亚微米级RDX

为了获得粒径分布均匀的细化RDX,在超重力反应器中,以丙酮-水作为溶剂-反溶剂重结晶体系,添加聚乙烯吡咯烷酮(PVP)作为表面活性剂,制备了亚微米级RDX。研究了RDX溶液浓度、PVP含量以及超重力反应器转速对RDX形貌和尺寸的影响,获得最优工艺条件,利用SEM、XRD和FT-IR对其形貌、晶体结构和分子结构进行了表征,并采用DSC研究了RDX的热分解过程。结果表明,在RDX溶液浓度为0.04g/mL、PVP浓度为0.2g/L、超重力反应器转速为1500r/min时,制备了平均粒径为0.54μm的亚微米级RDX,细化处理未改变RDX的晶型;与原料RDX相比,亚微米级RDX的分解峰温提前了1.2℃,热分解活化能从180~250kJ/mol降至约150kJ/mol。     

Investigation of the reaction zone in heterogeneous explosives substances using an electrical conductivity method

A technique for measuring the electrical conductivity profile behind a detonation wave front with a resolution of about 0.1 mm was used to analyze the reaction zone in heterogeneous explosives. TNT-RDX mixtures, RDX with additives of water, NaCl, and a saturated aqueous solution of NaCl, and pure RDX of low density were studied. It was shown that the particle size of the explosive can have a significant effect on the structure of the reaction zone. The most narrow conducting zone (0.22 mm) was observed in fine RDX of density 1.2 g/cm³. __________ Translated from Fizika Goreniya i Vzryva, Vol. 45, No. 2, pp. 109–115, March–April, 2008.     

Validation of the rancimat test for the assessment of the relative stability of fish oils

The induction periods for the peroxidation of various fish oils at 55–90°C were studied by the Rancimat test. The natural logarithms of the induction periods varied linearly with respect to temperature, with a mean coefficient of −7.5×10⁻²°C⁻¹, which was significantly different from that reported for vegetable oils. The activation energy for the formation of volatile acids had a mean value of 38.9 kJ/mol and was independent of the fish oil source. Peroxide formation under Rancimat test conditions followed first-order kinetics. The same kinetics were followed under Schaal Oven test conditions (forced-air oven, 60°C). On the basis of the results obtained, the Rancimat test appears to be useful in determining the relative stabilities of fish oils without the change in peroxide decomposition kinetics that may occur at elevated temperatures.     

Melt Phase Decomposition of RDX and Two Nitrosamine Derivatives

Thermal decomposition of hexahydro-1,3,5-trinitroso-s-triazine (TRDX), C₃H₆N₃(NO)₃, and hexahydro-1,3-dinitro-5-nitroso-s-triazine (MRDX), C₃H₆N₃(NO₂)₂(NO), was studied by DTA and TGA in argon atmosphere, which was showing overall first-order kinetics. The results are compared with those for RDX in order to determine the effect of replacing > NNO₂ group with > NNO. The decomposition of the admixture of RDX/TRDX (50/50 by weight) was also tested. The kinetic parameters calculated are: for RDX, ln k = 43.1–47,900/RT, for MRDX ln k = 34.3–37,200/RT, for TRDX ln k = 29. 4–30,500/RT, while for the RDX/TRDX admixture, ln k = 37.0–39,700/RT, where k is in s⁻¹. The melt phase decomposition products of RDX, MRDX, and TRDX condensed on a NaCl plate which was placed 2 cm above the sample cell were almost exactly the same in IR measurements. RDX is soluble in liquefied TRDX and the decomposition of RDX is accelerated by its liquefaction.     

RDX基可燃材料的热力学性能,非等温反应动力学及安全性研究

用TG和DSC研究了RDX基微孔可燃材料的热行为,用非等温DSC研究了其放热反应动力学,用Kissinger和Ozawa方法计算了可燃材料的动力学参数;基于Kissinger方法,研究了组分间的相容性;采用耐热和吸湿试验进行了微孔可燃材料的耐热性和吸湿性评价.结果表明,可燃材料的分解被看作是两步反应:第一阶段是吸热熔融反应,无质量损失,第二阶段是放热反应,有质量损失;用Kissinger和Ozawa方法得到的活化能相近,可燃材料的活化能均低于纯RDX的分解活化能;黏结剂PMMA、CA与固体填料RDX相容性好,相容性等级为1级;热爆炸临界温度与RDX相近.新型微孔可燃材料的其他性能优于传统可燃材料.     

Investigation of Diamond Synthesis from a Mixture of an Explosive with a Carbon Additive Using a Tracer Technique

The synthesis of detonation diamonds from a mixture of RDX labeled by C¹⁴ isotope with soot was studied experimentally. It was shown that a considerable portion of the diamonds (24.7 ± 3.4)% are formed from the carbon of RDX molecules. The degree of conversion of the carbon atoms of soot to the diamond phase is (16.0 ± 1.6)%. __________ Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 5, pp. 117–118, September–October, 2005.     

Characteristics of RDX combustion zones at different pressures and initial temperatures

The RDX burning rates and temperature profiles in the combustion wave are measured with the pressure and initial temperature varied within wide limits. Parameters of combustion waves are found. The gas phase of RDX is demonstrated to have a single-zone structure. Two regimes of RDX combustion are found: a basic regime at p > 0.1 MPa and a special regime at p ≤ 0.1 MPa. The main characteristics of these regimes are obtained, and the wave regions responsible for the burning rate are determined. Both regimes are characterized by wide reaction zones in the gas phase. The processes of vaporization and decomposition of the condensed phase proceed simultaneously on the burning surface. The fraction of thermal expansion in the reaction layer of this phase is estimated. Laws of RDX gasiffication (pyrolysis) in the combustion wave are found, which turn out to be the same as those for HMX. Distributions of the heat-release rate in the combustion wave (in the reaction layer of the condensed phase and in the gas phase) are obtained. Sensitivity of the burning rate to the initial temperature is measured. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 5, pp. 32–45, September–October, 2006.     

Kinetics and mechanism of thermal decomposition of ammonium nitrate powder under the action of carbon black

It is shown that in the presence of carbon black, the decomposition rate of solid ammonium nitrate increases strongly (by more than seven orders of magnitude). The kinetic regularities of the decomposition in the temperature range 70–150°C are established. At relatively low temperatures, the process proceeds by a two-stage mechanism with corresponding acceleration at each stage. At elevated temperatures, the first stage is absent. The decomposition rate is proportional to the amount of carbon black in the mixture. The activation energy for the decomposition (≈30 kcal/mole) does not vary during transformation. Water decelerates the process. For a water content of ≈(4–5)%, an intermediate maximum of the deceleration is observed. The main gaseous decomposition product is N₂. The concurrent oxidation of carbon black is terminated by evolution of CO₂. The mechanism of the chemical transformations is discussed using the results obtained and information available on the kinetics of individual reactions. Translated fromFizika Goreniya i Vzryva, Vol. 36, No. 5, pp. 63–73, September–October, 2000.     

Detonation-wave structure in RDX dust in vacuum

A mathematical model for detonation of suspensions of volatile secondary explosives in vacuum that takes into account the nonuniform temperature distribution inside the particles in flow of gaseous products is considered. The nonshock structure of stationary detonation, in the RDX dust in vacuum is studied. The parameters of a two-phase flow in the reaction zone and its length are calculated as a function of the mass concentration and sizes of the RDX particles. Lavrent’ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences Novosibirsk 630090. Translated from Fizika Goreniya i Vzryva, Vol. 33, No. 3, pp. 95–103, May–June, 1997.     

Effects of phenyl-s-triazine moieties on thermal stability and degradation behavior of aromatic polyether sulfones

The effect of the incorporation of phenyl-s-triazine units into the main chain of phthalazinone-based polyether sulfones on initial decomposition temperature, activation energy, thermal-mechanical property and possible degradation mechanism has been investigated. To this purpose, decomposition of poly(phthalazinone ether sulfone phenyl-s-triazine) copolymers (PPESPs) of different monomer compositions have been studied by utilizing thermogravimetry and differential scanning calorimetry. Non-isothermal experiments under nitrogen were performed, and the apparent activation energy (E _a) was calculated by isoconversional and conversional methods including the methods of Flynn-Wall-Ozawa, Friedman and Kissinger. In the conversion range (5–30%) studied, solid-state decomposition process of PPESPs is found to be a mechanism involving phase boundary controlled reaction (E _a: 189–201 kJ mol⁻¹) except that phenyl-s-triazine-rich copolymers exhibit a mechanism involving three-dimensional diffusion (E _a: 196–225 kJ mol⁻¹) in terms of Coats–Redfern method. The phenyl-s-triazine-rich copolymers display much higher E _a and slighter mechanical property-change compared to sulfone-rich copolymers and generic aromatic polyether sulfone, suggesting strong stabilizing effect of the phenyl-s-triazine moieties.     

Effectiveness of Phlegmatizers in Explosive Compositions under Mechanical Loading

The mechanism of the effect of phlegmatizers in phlegmatized nitramines under mechanical loading is studied. Current concepts regarding the effect of phlegmatizers on the sensitivity of energetic materials to impact, friction, and vibration are considered; insufficiency of experimental data of this effect is noted. Experimental estimates of the phlegmatizing effect of various phlegmatizers on HMX are given. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 1, pp. 100–105, January–February, 2006.     

Theoretical Study of Mechanism and Kinetics of the Reaction of NO2 with s‐Triazine

The decomposition of nitramines explosives have been of great interest for a long time. However, theoretical investigations have concentrated mainly on unimolecular decomposition whereas bimolecular reactions have received only little attention. In this paper, the bimolecular reaction between NO₂ with s‐triazine (TAZ), which is an initial product during the decomposition process of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) is investigated. The structures and potential energy surface (PES) are explored at B3LYP/6‐31G(d,p) and B3P86/6‐31G(d,p) levels, and the energies are refined using the CCSD(T)/cc‐pVTZ methods. The mechanism of the reaction is analyzed. Quantum chemistry calculations reveal that the title reactions possess small barriers that can be similar to, or smaller than that of initial decomposition reactions of RDX, which suggests that bimolecular reactions are also of great importance, and should be further investigated. Moreover, the kinetics were investigated to verify the proposed mechanism of the reaction.