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1

Preparation and Characterization of Ultrafine HMX/TATB Explosive Co-crystals

An C., Li H., Zhang Y., Ye B., Xu C., Wang J.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 4

876--887

EN

An explosive co-crystal of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) was prepared by the ball milling method. The raw materials and co-crystals were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and Raman spectroscopy. Impact and friction sensitivity of the co-crystals were tested and analyzed. The results showed that the HMX/TATB co-crystals are spherical in shape and 100-300 nm in size. The co-crystals are different from anintimate mixture of HMX/TATB and they exhibit a new co-crystal structure. HMX/TATB co-crystals are formed by N-O···H hydrogen bonding between −NO2 (HMX) and −NH2 (TATB). The drop height of ultrafine HMX/TATB explosive co-crystals is 12.7 cm higher than that of ultrafine HMX, whilst the explosion probability of friction is 20% lower than that of ultrafine HMX. Ultrafine HMX/TATB explosive co-crystals are difficult to initiate under impact and friction conditions.

2

Fabrication and Characterization of PMMA/HMX-based Microcapsules via in situ Polymerization

Jia X., Hou C., Tan Y., Wang J., Ye B.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 3

559--572

EN

Microcapsule technology was applied with nitramine explosives to improve their performance. Polymethyl Methacrylate (PMMA) was selected for the fabrication of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) based microcapsules. The PMMA/HMX-based microcapsules were prepared via a facile in situ polymerization of PMMA on the surface of the HMX crystals. Structural characterization of the PMMA/HMX microcapsules was studied systematically by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, and their thermal durability as well as their mechanical sensitivities were measured. The results indicated that spherical microcapsules were formed, with PMMA as the capsule wall and HMX as the core material. The SEM results showed that the grains of the PMMA/HMX microcapsules were spherical and that the particle distribution was homogeneous. XRD and FT-IR analyses indicated that the HMX polymorph was preserved in the optimal β-form during the whole preparative process. The DSC results showed that the PMMA/HMX microcapsules had better thermal decomposition performance, and that the apparent activation energy of the microcapsules had increased by 47.3 kJ/mol compared to the recrystallized HMX, and its thermal stability had greatly improved. In addition, the drop height (H50) had increased from 30.45 cm to 58.49 cm, an increase of 65.81%. Thus, microcapsule technology will have a very wide range of applications in reducing the sensitivity of high energy materials in the future.

3

Rapid and simple analysis of trace levels of three explosives in soil by liquid chromatography - tandem mass spektrometry

Yenel G. F., Anilanmert B., Cengiz S.

Acta Chromatographica

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2017

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Vol. 29, no. 1

45--56

EN

The analysis of trace levels of explosives in post-blast debris is critical in homeland security, environmental analysis, and crime scene forensic investigations. A fast and a selective determination method with high recovery was developed for the common explosives 2,4,6-trinitrotoluene (TNT), 3,5-trinitro-1,3,5-triazacyclohexane (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) in soil, using liquid chromatography - tandem mass spectrometry (LC-MS/MS). An easy and practical sample preparation method was developed using 4.00 mL acidified acetone with 0.25% HCl. After the easy evaporation of acetone extract, 10 min LC-MS/MS analysis provided a clear separation in column. Short duration of the whole procedure allows the use of this method in routine analysis. As a result of the analysis performed in spiked soils in 50.0, 100.0, and 250.0 ng g -1 concentrations, high recoveries such as 100.4 (±8.8)% for RDX, 96.9 (±10.5)% for HMX, and 97.6 (±13.9)% for TNT were obtained. Limit of detection (LOD) and limit of quantification (LOQ) values obtained from the analysis of the spiked soils were 4.3 ng g -1 and 7.00 ng g -1 for RDX, 6.8 ng g -1 and 10.0 ng g -1 for HMX, and 18.9 ng g -1 and 38.0 ng g -1 for TNT, respectively. The Horwitz Ratio (HorRat) calculation was used to evaluate if the inter-day and inter-analyst precisions were in the acceptable limits. The method was successfully applied to three artificial explosion samples for detection of explosives.

4

Investigation of the Properties of Polymer Bonded Explosives Based on 1,1-Diamino-2,2-dinitroethene (FOX-7) and 1,3,5,7-Tetranitro-1,3,5,7-tetraazacyclooctane (HMX)

Chyłek Z., Jurkiewicz R.

Central European Journal of Energetic Materials

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2016

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Vol. 13, no. 4

859--870

EN

The influence of polymeric matrices on the physical properties and stability of polymer bonded explosives based on FOX-7 (1,1-diamino-2,2-dinitroethene) and HMX (1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane) was investigated. Samples of explosives were prepared with different polymeric additives e.g. nonylphenylpolyoxyethyleneglycol ethers (ROKAFENOL), silicone greases and poly(3-methyl-3-nitroxymethyloxetane) (Poly(NIMMO)). The mass ratio of polymeric matrices to explosives was determined experimentally in order to obtain plastic samples stable at room temperature. The most promising products were tested for sensitivity to mechanical and thermal stimuli. Determinations of the critical diameter and detonation velocity were also performed. The use of silicone grease in the mixture containing Poly(NIMMO) gave the most desirable results, that is to say a combination of high performance and high stability.

5

Studies on Tungsten Based High Density Cast Polymer Bonded Explosive (PBX) Formulations

Vadhe P. P., Manickam S., Rahujade N., Kondra A., Prasad U., Sinha R. K.

Central European Journal of Energetic Materials

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2015

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Vol. 12, no. 3

497--506

EN

Aluminized melt-cast TNT and PBX (cast/pressed) based compositions have been widely studied and used in different warheads for various applications,such as air blast, underwater blast, thermobaric effects, etc. Tungsten (W) based cast PBX formulations are the least reported in the literature. We have partially replaced RDX or HMX in the control PBX formulation with 15 to 25% W powder and investigated the effect of this on the ease of processing, density, sensitivity, mechanical properties and explosive performance. The viscosity was improved from 9 to 3 kPoise, and the density by about 12 to 25% on the addition of W powder to the PBX formulations. The sensitivity to impact for the RDX/Wand HMX/W based PBX formulations was improved by 12 to 37%. The reinforcing effect of the W powder caused an increase in hardness (Shore A) by 16 to 45%. A decreasing trend in the velocity of detonation (VOD) was observed because of the replacement of the nitramine content (RDX/HMX) with W powder. The approximate detonation pressure of RDX/W/HTPB (65/20/15), roughly calculated by the Kamlet-Jacobs method, is better than the other tungsten based formulations investigated.

6

Process Optimization and Characterization of an HMX/Viton Nanocomposite

Shi X., Wang C., Wang J., Li X., An C., Wang J., Ji W.

Central European Journal of Energetic Materials

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2015

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Vol. 12, no. 3

487--495

EN

HMX/Viton A nanocomposites were prepared by a spray drying process using different processing parameters, which included the dry gas inlet temperature, the air flow rate, and the solution feed flow rate. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to characterize the nanocomposites. The effects of the processing parameters on the morphology of the samples were investigated and are discussed. The thermal decomposition behaviour and impact sensitivity of the raw HMX and HMX/Viton A nanocomposites were also measured and compared. Optimal morphology and dispersion of the coated samples was achieved when the dry gas inlet temperature and the air and solution feed flow rates were 55 °C, 660 L/h and 1.5 mL/min, respectively. Under these optimal processing conditions, the nanocomposites were spherical in shape, ranged from 0.2-2 μm in size, and were composed of many tiny particles of 50-100 nm in size. The crystal phase of the nanocomposites was the same as that of raw HMX. Compared with those of raw HMX, the melting point and impact sensitivity of the nanocomposites were lower and the thermal decomposition rate was slightly higher.

7

Preparation and Characterization of HMX/Estane Nanocomposites

Shi X., Wang J., Li X., An Ch.

Central European Journal of Energetic Materials

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2014

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Vol. 11, no. 3

433--442

EN

A new insensitive explosive based on octahydro-1,3,5,7-tetranitro1,3,5,7-tetrazocine (HMX) was prepared by spray drying using Estane 5703 as a binder. Scanning electron microscopy was used to characterize the morphology and particle size of the HMX/Estane 5703 nanocomposites. The composites were analyzed by X-ray diffractometry and differential scanning calorimetry and their impact sensitivity was determined. For comparison, raw HMX was also tested using these three methods. The nanocomposite morphology was found to be microspherical (1 to 8 μm diameter) and composed of many tiny particles, 30 to 150 nm in size. The crystal type of the HMX/Estane 5703 nanocomposites was unchanged. The activation energy, self-ignition temperature and average drop height of the raw HMX were 515.66 kJ·mol-1, 278.63 °C and 18.4 cm, respectively. In comparison, the corresponding values for the HMX/Estane 5703 nanocomposites were 488.92 kJ·mol-1, 279.3 °C and 75.4 cm, respectively.

8

Insensitive HMX (Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) Nanocrystals Fabricated by High-Yield, Low-Cost Mechanical Milling

Wang Y., Jiang W., Song X., Deng G., Li F.

Central European Journal of Energetic Materials

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2013

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Vol. 10, no. 2

277--287

EN

A mechanical approach had been adopted for fabricating HMX nanoparticles. This fabrication method avoided the recrystallization process and was different from the traditional methods employed to prepare nanoexplosives. In particular, the high yield and low cost increased the possibility of its industrial application. Specifcally, HMX particles, that had a mean size of 0.27 μm, were prepared by mechanical milling; a signifcant proportion of nano-HMX (<100 nm) were present and these were observed by TEM and SEM images. The thermal decomposition of HMX samples before and after pulverization was investigated by TG/DSC analysis. The results indicated that there was no obvious difference between the thermographs of raw and pulverized HMX. The HMX samples were investigated by friction, impact, and shock sensitivity tests. High safety was confrmed since pulverized HMX was far more insensitive than raw HMX; indeed the shock sensitivity of pulverized HMX was about 60 percent lower than that of raw HMX.

9

Evaluation of the thermo-mechanical and explosive properties of bimodal and hybrid polymer bonded explosive (PBX) compositions based on HNS and HMX

Kaur J., Arya V. P., Kaur G., Lata P.

Central European Journal of Energetic Materials

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2013

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Vol. 10, no. 3

371--391

EN

In the present paper, a series of bimodal PBX compositions containing coarse (90 μm) and fine (<1 μm) HNS (2,2’4,4’6,6’-hexanitrostilbene) and hybrid PBX compositions based on HNS and HMX (1,3,5,7-tetranitro-1,3,5,7- tetraazacyclooctane) in varying mass ratios, along with the fluoropolymer Viton-A, a vinylidene fluoride and hexafluoropropylene copolymer, as a binder (5%), have been prepared on the lab scale. In order to observe any effect of incorporating fine HNS particles with coarse ones and the effect of replacing HNS with HMX in all types of bimodal and hybrid PBX compositions, the samples were characterized for composition analysis, thermal behavior and morphological analysis as well as evaluated for their mechanical and explosive properties including sensitiveness tests and detonic properties. The data showed that incorporation of fine HNS into coarse particles of HNS in the bimodal PBX resulted in an increase in mechanical strength and a decrease in friction and impact sensitivity, as well as an enhanced performance compared to PBXs based on coarse HNS alone. Viton-A based hybrid PBX compositions provided better mechanical and sensitivity properties as compared to conventional explosive compositions based exclusively on HMX or HNS and the performance of the PBX compositions increased with increasing HMX content.

10

Effect of Different Polymeric Matrices on the Sensitivity and Performance of Interesting Cyclic Nitramines

Elbeih A., Zeman S., Jungova M., Akstein Z.

Central European Journal of Energetic Materials

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2012

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Vol. 9, nr 2

131-138

EN

Different polymeric matrices, based on butadiene-styrene rubber, polymethyl-methacrylate and silicone binders, were investigated for their ability to decrease the sensitivity of explosives to different mechanical stimuli. A series of plastic explosives based on four different nitramines, namely RDX (1,3,5-trinitro- 1,3,5-triazacyclohexane), β-HMX (β-1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane), BCHMX (bicycloHMX, cis-1,3,4,6-tetranitro-octahydroimidazo-[4,5- d ]imidazole) and ε -HNIW (ε -2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, ε-CL-20), bonded by the selected polymeric matrices were prepared. Sensitivity to impact of all of the plastic explosives prepared as well as of the pure explosives, was measured using the fall hammer test. Sensitivity to friction was determined using the BAM friction test. The performance was studied using the ballistic mortar test and the results were recorded relative to TNT (trinitrotoluene) as reference. By comparing the results of impact and friction sensitivities, it is obvious that the mechanism of transfer of the friction force to the reaction center of the nitramine molecule should be different from that of impact energy transfer. The silicone binder appeared to be the best polymer for decreasing the sensitivity of explosives. The results of the ballistic mortar proved that the performance of the plastic explosives prepared is affected by the type and weight percentage of the binder in each sample.

11

Synthesis of HMX via Nitrolysis of DPT Catalyzed by Acidic Ionic Liquids

He Z., Luo J., Lu Ch., Xu R., Li J.

Central European Journal of Energetic Materials

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2011

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Vol. 8, nr 2

83-91

EN

The direct nitrolysis of DPT to synthesize HMX with ionic liquids (ILs) as catalysts was investigated. The results showed that [Et3NH] HSO4 was the best catalyst among 18 ILs used and the yield of HMX was up to 61% against 45% without IL. The ILs could be effciently recovered by simple distillation and extraction after reaction without any apparent loss of catalytic activity even after 10 times recycling.

12

Thermal Stability and Detonation Characteristics of Pressed and Elastic Explosives on the Basis of Selected Cyclic Nitramines

Elbeih A., Pachmáň J., Zeman S., Trzciński W. A., Akstein Z., Sućeska M.

Central European Journal of Energetic Materials

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2010

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Vol. 7, nr 3

217-232

EN

Bicyclo-HM X (cis-1,3,4,6-tetranitro-octahydroimidazo-[4,5-d] imidazole or BCHM X) was studied as a plastic explosive bonded with the C4 matrix and with Viton A. Also a series of nitramines namely RDX (1,3,5-trinitro-1,3,5=triazinane), HM X (1,3,5,7-tetranitro-1,3,5,7-tetrazocane) and HNIW (ĺ-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, ĺ-CL-20) were studied for comparison with the same types of binders. The detonation velocity, D, of all prepared mixtures was measured. Their thermal stability was determined using non-isothermal differential thermal analysis (DTA). While the C4 matrix lowers the thermal stability of the resulting explosives, Viton A enhances this stability. Approximate relationships between the peaks of exothermic decomposition and the D values were found. The detonation parameters were also calculated by means of Kamlet & Jacobs method, CHEETAH and improved EXPLO5 code for all the mixtures. From the measured D values and the calculated detonation parameters, it is obvious that the detonation parameters of BCHM X-mixtures are very close to HM X-explosives and better than those of RDX-mixtures. It was found that the C4 matrix reduces the difference between the values of energy of detonation in the studied C4 mixtures. As expected, the pressed HNIW-Viton A mixture has the highest detonation parameters of all of the prepared mixtures.

13

Study of the Interaction of Polynitro Compounds with Transition Metals Coordination Complexes with 1,5-Pentamethylenetetrazole as a Ligand

Ilyushin M. A., Bachurina I. V., Smirnov A. V., Tselinsky I. V., Shugalei I. V.

Central European Journal of Energetic Materials

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2010

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Vol. 7, nr 1

33-46

EN

Perchlorate complexes of d-metals with tetrazole-containing ligands are proposed for application both as explosives for safe initiation systems and as modifers of burning rate for propellants. However, the problem of compatibility of organic polynitro compounds with the complexes has not yet been solved. In the present article the results of investigation of the infuence of perchlorate complexes of cobalt, copper and nickel with 1,5-pentamethylentetrazole as a ligand on thermal decomposition of energetic materials ranging from 1,1-diamino-2,2- dinitroethylene (FOX-7), to cyclic cyclotetramethylenetetranitroamine (HMX) and caged hexanitrohexaazaizowurtzitane (CL-20) have been reported. Thermal stability of the individual compounds and their mixtures with coordination complexes has been assessed on the basis of differential thermal analysis and the study of ignition temperatures after 5-second delay. The fraction of the complexes in the formulations with polynitro compounds amounted to ~10%.

14

Rate of the energy release in high explosives containing nano-size boron particles

Kanel G. I., Utkin A. V., Razorenov S. V.

Central European Journal of Energetic Materials

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2009

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Vol. 6, nr 1

15-30

EN

With a goal to obtain information on rate of the high explosive decomposition and equation of state of the HE formulations and detonation products, measurements of the pressure and particle velocity profiles of shock and detonation waves have been performed for pure coarse-grain and fine-grain HMX and for the HMX+16.4% boron mixture. For these measurements, the manganin pressure gauges and the laser Doppler velocimeter VISAR were applied. Effect of boron in the energy release process was observed both in the detonation and shock-wave initiation regimes.

15

Combustion of Energetic Systems Based on HMX and Aluminum: Infuence of Particle Size and Mixing Technology

Muravyev N., Frolov Y., Pivkina A., Monogarov K., Ivanov D., Meerov D., Fomenkov I.

Central European Journal of Energetic Materials

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2009

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Vol. 6, nr 2

195-210

EN

In this work the complex experimental investigation of the microstructure and burning parameters of HMX-monopropellant and 25%Al/75%HMX energetic systems was carried on with the particle size variation. Components, their mixtures, pressed samples, and the combustion products (agglomerates) collected from a burning surface by QPCB (quench particle collection bomb) technique were investigated. Two types of HMX particles: micro-sized (mHMX) and ultrafne (uHMX) and aluminium powders: micro- and ultra-sized (ALEXTM) were used. Morphology and particle size were examined by atomic-force microscopy (AFM), scanning electron microscopy (SEM) and BET-analysis. AFM analysis shows the ALEXTM average volume particle size is 180 nm. It was shown, that the monopropellant's burning rates of the micro- and ultra-sized HMX are almost identical in the pressure range 20-100 atm. Two mixing technologies to prepare Al/HMX compositions were used: (i) conventional "dry" mixing and (ii) "wet" technique with ultrasonic processing in diethyl ether. Applying of ultrasonic technique results in a burning rate increase up to 18% comparing to "dry" mixing (under pressure 60 atm). The highest combustion rate was determined for composition of mHMX/ALEXTM (porosity 13%). Infuence of component N. Muravyev et al. size and composition's microstructure on the burning rate of energetic systems is discussed and analyzed.

16

A Comparison of Properties of Aluminized Composite Propellants Containing HMX and FOX-7

Florczak B.

Central European Journal of Energetic Materials

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2008

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Vol. 5, nr 3-4

103-111

EN

Modern rocket propellants contain inter alia nitroamines (i.e. RDX, HMX). Therefore, the detonation properties of composite solid propellants are very important for good functioning of rocket motors and for storage. One of the new materials of that kind, with low sensitivity, is FOX-7 which was applied here as one of the components of composite solid propellant. This paper presents the thermodynamical calculations and thermochemical research results as well as the results of a study of transition into detonation of an aluminized composite propellant containing HMX. The said properties were compared with those of a propellant containing FOX-7.

17

Research of High Explosives Based on RDX, HMX and CL-20 in the Small Scale Underwater Test Examination

Koślik P., Staś J., Wilk Z., Zakrzewski A.

Central European Journal of Energetic Materials

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2007

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Vol. 4, nr 3

3-13

EN

HNIW(CL-20), HMX and RDX have been examined in the small scale underwater test. Pressure curves of detonating materials were obtained. The comparison between HNIW, HMX and RDX pressure waves parameters were estimated. Applicability of the small scale underwater test for high explosives examining became proved.

18

Particle Design of Energetic Materials

Teipel U.

Central European Journal of Energetic Materials

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2005

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Vol. 2, nr 2

55-69

EN

The crystal quality and the internal microstructure of crystals have a great influence on the sensitivity of energetic materials. Besides, the particle size and the particle size distribution are of great importance to the processing technology of energetic materials. Particle properties can especially be influenced by applying different crystallization techniques, such as cooling crystallization, membrane crystallization, emulsion crystallization and others. The objective of the investigations was to determine the interrelationship between the properties of the gained crystals and the process parameters. Special attention was directed to the qualitative and quantitative examination of crystal defects and their dependence on the experimental conditions. Besides, the morphology and structure of crystals were calculated by molecular modelling. The effect of crystal defects on the sensitivity of the material was tested on different collectives of particles having varying amount of crystal defects.

19

Dislocation - Assisted Initiation of Energetic Materials

Armstrong R. W.

Central European Journal of Energetic Materials

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2005

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Vol. 2, nr 3

21-37

EN

The role of dislocations in assisting initiation of (explosive) chemical decomposition of energetic materials has connection with the known influences for crystals and polycrystals of dislocations facilitating permanent deformations and phase transformations. X-ray topographic observation of relatively few dislocations in solution-grown crystals relates to the influence of large Burgers (displacement) vectors that are characteristic of molecular crystal bonding. Both model evaluations of the load dependence of cracking at hardness indentations and the derived hardness stress-strain behaviors show that dislocation movement is difficult whether in the indentation strain fields or at the tips of indentation-induced cracks. Thus, energetic crystals are elastically compliant, plastically hard, and relatively brittle [1]. Nevertheless, cracking is shown to be facilitated by the shear stress driven, normally limited, dislocation flow that, on molecular dynamics and dislocation pile-up model bases, is shown to be especially prone to producing localized hot spot heating for explosive initiations. Such model consideration is in agreement with greater dropweight heights being required to initiate smaller crystals. The crystal size effect carries over to more difficult combustion occurring for compaction of smaller crystals. The total results relate to dual advantages of greater strength and reduced mechanical sensitivity accruing for the development of nanocrystal formulations. In consequence, also, several levels of dislocation-assisted modeling are described for initiation mechanisms under shock wave loading conditions.