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1

Research on the Detonation Process of Explosives Containing Sodium Azide

Papliński Andrzej, Maranda Andrzej

Central European Journal of Energetic Materials

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2019

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Vol. 16, no. 4

520--532

EN

The detonation performance of aluminized energetic materials with enriched nitrogen content is examined. Sodium azide (NaN3, SA) was considered as the component to enhance the nitrogen content in explosive mixtures. SA explosives based on hexogen (RDX) as the representative C-H-N-O explosive, and on ammonium nitrate(V) (NH4NO3, AN) were investigated. Powdered (Alp) or flaked (Alf) aluminum was added as an energetic additive. Detonation of mixtures with added SA revealed highly non-ideal behaviour. Thermodynamic evaluations have been carried out to assess the magnitude of the energy evolved in explosives with added SA, as well as to examine the possible influence of the formation of aluminum nitride (AlN(s)) on the detonation and explosion parameters. The results obtained indicated that, despite the relatively low observed detonation velocities, aluminized RDX/Al/SA and AN/Al/SA mixtures may attain explosion energies of about of 6 MJ/kg and higher. A considerably lower energetic outcome from the formation of AlN(s), in comparison with Al2O3(s), was noted.

2

Novel High-Nitrogen Content Energetic Compounds with High Detonation and Combustion Performance for use in Plastic Bonded Explosives (PBXs) and Composite Solid Propellants

Keshavarz M. H., Abadi Y. H., Esmaeilpour K., Damiri S., Oftadeh M.

Central European Journal of Energetic Materials

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2018

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Vol. 15, no. 2

364--375

EN

Five novel high-nitrogen content (N>50%) derivatives of tetrazole are introduced in the study reported here. The assessment of various properties of these compounds were performed, which include physicothermal properties (crystal density, condensed phase heat of formation, melting point, enthalpy of fusion and entropy of fusion), detonation performance (velocity and pressure of detonation, detonation temperature and power), sensitivity with respect to external stimuli (impact, shock, friction and electric spark) and combustion performance (specific impulse). The predicted results of these compounds are compared with dihydroxylammonium 5,5’-bistetrazole-1,1’-diolate (TKX-50) and octanitro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) as a high performance ionic salt and a neutral explosive, respectively. The novel energetic compounds were found to have higher detonation and combustion performance than either TKX-50 or HMX. The new explosives are therefore good candidates to obtain high detonation and combustion performance in plastic bonded explosives (PBXs) and composite solid propellants, respectively.

3

Comparative Theoretical Investigation on Energetic Substituted Furazanyl Ethers

Liu N., Wang K., Shu Y., Zeman S., Wang B., Wang W.

Central European Journal of Energetic Materials

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2018

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Vol. 15, no. 1

47--71

EN

Furazanyl ether has great potential to be an important candidate as a casting explosive and energetic plasticizer. The density functional theory (DFT) method was used to investigate the heats of formation (HOFs), molecular stability, detonation performance and melting point of a series of substituted furazanyl ethers at B3LYP/6-311G(d,p) level. The results show that the introduction of –N3 or –N(O)=N– groups significantly improves the HOFs values of the derivatives. The bond dissociation energies (BDEs) were analyzed, showing that the N–O bond in the furazan ring is the weakest for most compounds and the ring is vulnerable to cleavage in thermal decomposition. The calculation of density, detonation velocities and detonation pressures suggests that the substitution of –NF2, –CF(NO2)2, furoxan or –N(O)=N– group is an effective method for enhancing their detonation performance. The melting points were determined according to the variation of specific heat capacity, and good estimates were obtained in comparison with the available experimental data. Taking into account the detonation performance and melting point, four compounds are favoured for application in melt cast explosive or energetic plasticizers.

4

4-Amino-3-hydrazino-1,2,4-triazole: a Precursor for the Preparation of Divalent Energetic Materials

Lin Q., Wang P., Sun Q., Lu M.

Central European Journal of Energetic Materials

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2018

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Vol. 15, no. 1

18--29

EN

4-Amino-3-hydrazino-1,2,4-triazole (AHT) was developed as a divalent cation. The multivalent structure can be used to increase the number of nitrogen-rich heterocycles, thereby increasing the heat of formation and improving the detonation performance. Herein we report on a family of divalent energetic salts, which exhibit excellent properties, viz. acceptable density, good detonation performance, and desirable thermal and impact stabilities. The structural features of the salts were further determined by single-crystal X-ray diffraction. In addition, the detonation properties calculated for these energetic salts identified them as competitively energetic compounds.

5

Computational Investigation on the Structure and Performance of Novel 4,7-dinitro-furazano-[3,4-d]-pyridazine Derivatives

Wang K., Shu Y., Liu N., Ding X., Wu Z., Lu Y.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 1

26--46

EN

Seven novel energetic 4,7-dinitro-furazano-[3,4-d]-pyridazine derivatives were designed, and their optimized structures and performances were studied by density functional theory (DFT) at B3LYP/6-311g(d,p) level. The detonation performances were estimated by the Kamlet-Jacobs equations. The results show that these compounds have high crystal densities (1.818-1.925 g·cm−3), detonation velocities (8.51-9.56 km·s−1) and detonation pressures (32.28-41.70 GPa). The bond dissociation energies (BDEs) of the weakest bond (N–O bond) vary from 70.889 kJ·mol−1 to 173.283 kJ·mol−1, and some of them exhibit higher BDEs than that of RDX (N–NO2 bond, 149.654 kJ·mol−1) and HMX (N–NO2 bond, 154.905 kJ·mol−1). M4 and M5 exhibit similar and higher detonation performance than RDX (8.81 km·s−1, 34.47 GPa). The detonation performance of M7 (9.56 km·s−1, 41.70 GPa) even surpasses that of HMX (9.10 km·s−1, 39.00 GPa). Otherwise, the specific impulse values of M1-M7 (266-279 s) outperform HMX (266 s) by 0-13 s, which indicates that M1-M7 may show better performance as monopropellants. It is concluded that density, heat of formation, stability, detonation performance and specific impulse of the designed compounds depend on the position and number of the N→O oxidation bonds.

6

Microstructure, Mechanical and Detonation Properties of Elastomeric Micro/Ultrafine-rubber Modified TNT-based Molten Energetic Composites

Ma Q., Wang P.-S., Luo G., Wen M.-P., Gao D.-Y., Zheng B.-H., Shu Y.-J.

Central European Journal of Energetic Materials

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2015

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Vol. 12, no. 4

723--743

EN

Elastomeric micro- and ultrafine-rubber are first considered as binders in melt-cast explosives for improving the mechanical properties. Acrylonitrile-butadiene rubber (NBR), in ultrafine fully vulcanized form (UF-NBR), carboxylated acrylonitrile-butadiene rubber (CNBR), in ultrafine fully vulcanized form (UF-CNBR), styrene-butadiene rubber (SBR), in ultrafine fully vulcanized form (UF-SBR), carboxylated styrene-butadiene rubber (CSBR), in ultrafine fully vulcanized form (UF-CSBR), acrylic rubber (ACM), in ultrafine fully vulcanized form (UF-ACM), room temperature vulcanized silicone rubber (RTV), in ultrafine fully vulcanized form (UF-RTV) and polytetrafluoroethene (PTFE) in micro-rubber form (PTFE-M) were utilized for modifying 2,4,6-trinitrotoluene (TNT) based melt-cast explosives. Based on their dispersity in TNT and RDX slurry, only UF-NBR, UF-CNBR and PTFE-M can be used. In the modification experiment, their influence on the mechanical and detonation performance of the matrixes were studied, as well as the impact sensitivity. Compared with PTFE-M and UF-CNBR, UF-NBR improved the tensile and compressive strength of the original formulation CYCLOTOL-65/35. The toughening mechanism was also explained through interfacial interactions and fracture energy analysis. The predicted detonation properties of the modified formulations (detonation pressure variations from 26 to 28 GPa, detonation velocity variations from 7900 to 8100 m/s) are at the same energy level as CYCLOTOL-65/35. In addition, the drop hammer impact testing results confirm that the formulation containing UF-NBR is more sensitive than the one with UF-CNBR, with the same amount of additive.

7

Tricyclic polyazine n-oxides as proposed energetic compounds

Politzer P., Lane P., Murray J. S.

Central European Journal of Energetic Materials

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2013

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Vol. 10, no. 3

305--323

EN

In designing proposed new explosives, we seek a balance between high detonation performance and low sensitivity. Accordingly we focus upon (1) planar molecules, for better packing efficiency and reduced shear strain upon impact/ shock, (2) high nitrogen content, for greater density and enthalpy of formation, (3) N→O linkages rather than NO2 or ONO2 groups as sources of oxygen, and (4) presence of NH2 groups, if possible, to increase density and diminish sensitivity. Here we report the results of a computational assessment of three tricyclic polyazine N-oxides that essentially satisfy these structural criteria. Their predicted crystal densities range from 1.96 to 2.03 g/cm3. The calculated solid phase enthalpies of formation are between 135 and 314 kcal/mol. The computed detonation velocities and detonation pressures are similar to HMX for two of the compounds and significantly greater for the third, exceeding even CL-20. Impact sensitivities were estimated on the basis of (1) the free space available in the respective crystal lattices, and (2) the molecular surface electrostatic potentials. All three compounds are expected to be less impact sensitive than both HMX and CL-20. One of the three in particular is suggested to represent the best balance between detonation performance and sensitivity.

8

Preparation and Performance of a Novel Water Gel Explosive Containing Expired Propellant Grains

Wang P., Xei X., He W.

Central European Journal of Energetic Materials

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2013

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Vol. 10, no. 4

495--507

EN

Novel water gel explosives containing expired single base and double base propellant grains were prepared by using a new gelling agent and a simple process. The shock wave overpressures and underwater output energies of the explosives were measured. The detonation performances of the explosives were also investigated. As the particle size of the propellant was increased, the detonation velocity, peak overpressure and underwater energy of the explosive containing single base propellant (NCP) were gradually reduced. Double base propellant (DBP) had low detonation sensitivity due to its thermoplasticity. When it was mixed with the appropriate quantity of NCP, DBP could also be reused. NCP acted as the sensitizer and energy source in the explosive containing both DBP and NCP. So the detonation velocity, peak overpressure and underwater energy of the explosive increased with the increase in ωNCP. With excellent detonation performance, these two kinds of water gel explosives can be used as opencast blasting agents.

9

Dft investigation of a high energy density polynitro compound, 2,2’-Bis(trinitromethyl)-5,5’-azo-1,2,3,4- tetrazole

Lin H., Zhu S. G., Chen P. Y., Li K., Li H. Z., Peng X. H.

Central European Journal of Energetic Materials

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2013

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Vol. 10, no. 3

325--338

EN

A novel polynitro compound, 2,2’-bis(trinitromethyl)-5,5’-azo- 1,2,3,4-tetrazole, was designed and investigated at the DFT-B3LYP/6-31G(d) level. Its properties, such as electronic structure, IR spectrum, heat of formation, thermodynamic properties and crystal structure, were predicted. This compound is most likely to crystallize in the P21 space group, and the corresponding cell parameters are Z = 2, a = 5.46 Å, b = 9.72 Å, c = 14.05 Å, α = 90°, β = 90°, γ = 90°. In addition, the detonation velocity and pressure were also estimated by using the empirical Kamlet-Jacobs equations, and were predicted to be 8.28 km/s and 31.61 GPa respectively. The oxygen balance of this compound is +13.79%, which indicates that it could serve as an oxidizer. Bond dissociation energy calculations show that the C(13)-N(21)O2 and C(14)-N(30)O2 bonds are the locations of thermal decomposition and that this compounds meets the thermal stability requirements as an exploitable explosive. Keywords: polynitro, electronic structure, thermodynamic properties, crystal structure, detonation performance, stability.

10

Badanie parametrów detonacyjnych i wrażliwości flegmatyzowanych materiałów wybuchowych opartych na FOX-7

Trzciński W. A., Chyłek Z., Cudziło S., Szymańczyk L.

Biuletyn Wojskowej Akademii Technicznej

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2008

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Vol. 57, nr 3

7-25

PL

W pracy otrzymano i zbadano właściwości detonacyjne flegmatyzowanego materiału wybuchowego FOX-7 (1,1-diamino-2,2-dinitroeten - DADNE) oraz jego mieszaniny z oktogenem. Wyznaczono dla tych materiałów prędkość i ciśnienie detonacji, zdolności miotające oraz energię detonacji. Określono wrażliwość na bodźce mechaniczne: tarcie, uderzenie i falę uderzeniową. Zbadano ich stabilność termiczną i kompatybilność składników. Praca jest kontynuacją poszukiwań nowych kompozycji do zastosowania w małowrażliwej amunicji.

EN

Phlegmatized FOX-7 (1,1-diamino-2,2-dinitroethylene - DADNE) and its mixture with HMX were prepared and their detonation properties were investigations. The detonation velocity, detonation pressure, acceleration ability and detonation energy were established. The sensitivity on mechanical stimuli (friction, impact and shock wave) was determined. Thermal stability and compatibility of composition were also tested. This work continues the investigation of new compositions for low vulnerability ammunition.

11

Influence of Geometry and Material Properties on an Explosive's Gurney Velocity and Energy

Backofen J. E.

Central European Journal of Energetic Materials

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2006

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Vol. 3, nr 4

23-40

EN

Experimental data from many scientific publications reveal that the copper cylinder test used internationally to measure an explosive's Gurney Velocity and Gurney Energy falls within a unique combination of geometry and material properties - factors affecting an explosive's measured performance. These data also support the need to use two separate propulsion events to model detonation-driven propulsion: a brisant first stage and a gas-dynamic second stage.