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1

Tetraamminecopper(II) Nitrate and Its Effects on Ammonium Nitrate(V)

Künzel M., Vodochodský O., Matyáš R., Jalový Z., Pachman J., Maixner J.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 1

169--183

EN

Tetraamminecopper(II) nitrate(V) (TACN) is a complex copper salt which is easily formed when ammonium nitrate (AN) comes into contact with copper. It is considered to be an unwanted contaminant of AN because of its sensitivity to mechanical stimuli and significant explosive properties. The formation of TACN by the reaction of copper with molten ammonium nitrate(V) was demonstrated by powder diffraction. Friction and impact sensitivity testing was performed and field experiments were then conducted to reveal the detonation parameters of TACN and its initiation capability towards ammonium nitrate. The dependence of the detonation velocity on charge diameter was revealed and the ideal detonation velocity of 3500 m·s−1 at 0.87 g·cm−3 was measured. AN with the addition of 16 wt.% of TACN was found to detonate when initiated with a small booster charge. Moreover, TACN was able to initiate detonation in fertilizer grade ammonium nitrate(V) under massive steel confinement. TACN should be therefore considered as a possible contributory initiation source in some large scale accidents. In this article, some properties of TACN are revealed which could be useful for the investigation of accidents.

2

Laminaty FRP w budownictwie – charakterystyka materiału i aspekty projektowania

Sobczyk B., Miśkiewicz M.

Materiały Budowlane

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2015

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nr 4

74--76

PL

W artykule przedstawiono charakterystykę laminatów polimerowych wzmacnianych włóknami. W pierwszej części zaprezentowano teoretyczne modele materiałowe, podstawowe zależności naprężenie-odkształcenie włókien, matrycy oraz laminatu powstałego przez połączenie obydwu składników. Na tej podstawie sformułowano zalecenia dotyczące praktycznego wykorzystania laminatu w kontekście jego wytężenia w projektowaniu elementów konstrukcyjnych. W drugiej części omówiono metody szacowania nośności kompozytów włóknistych z matrycą polimerową w kontekście metod zniszczenia: pierwszego (ang. First Ply Failure – FPF) i ostatniego włókna (ang. Last Ply Failure – LPF) oraz związane z nimi wybrane kryteria inicjacji zniszczenia.

EN

The article presents some characteristics of fibre reinforced polymer laminates. In the first part theoretical material models are presented. Especially, basic stress-strain relations for fibres, matrix and fibre reinforced polymer laminates are shown and described. On the basis of these relations some recommendations are formulated, concerning the practical range of material effort in the field of structural design. In the second part of the article load capacity estimation methods of fibre reinforced polymer laminates are presented. Selected failure initiation criteria are described together with First and Last Ply Failure estimation methods.

3

Recent Advances in the Study of the Initiation of Nitramines by Impact Using Their 15N NMR Chemical Shifts

Jungová M., Zeman S., Yan Q.-L.

Central European Journal of Energetic Materials

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2014

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Vol. 11, no. 3

383--393

EN

The relationship between the 15N NMR chemical shifts of aza nitrogen atoms in twelve nitramines and the impact sensitivity of these compounds, expressed as the drop energy, Edr, has been analyzed from the point of view of recently published findings. This relationship appears to be the best method for identifying the key atoms at the reaction centre of a given molecule. These atoms might be taken as “chemical hot spots”. The absence of any solid state influence on the chemical shifts, which were here determined in solution, does not have a fundamental influence on the reaction centre identification. The relationship discussed here confirms the close molecular structural dependence for drop energies (impact sensitivities) obtained for individual energetic materials (EMs) by means of a standard impact tester (Julius Peters) with the detection of the 50% probability of initiation based on acoustic detection. The dependence of impact sensitivity on specific crystal surfaces, using samples of individual EMs obtained by screening, should be investigated more extensively.

4

Recent advances in the study of the initiation of energetic materials rusing characteristics of their thermal decomposition. Part I, Cyclic nitramines

Zeman S., Yan Q.-L., Vlček M.

Central European Journal of Energetic Materials

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2014

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Vol. 11, no. 2

173--189

EN

Arrhenius parameters, Ea and log A, of 17 cyclic nitramines, derived from the Russian vacuum manometric method (SMM) and compatible thermoanalytical methods, have been used in this study. The detonation velocity, D, at maximum theoretical crystal density, of the nitramines in this study was taken as a characteristic of their detonation. On the basis of known relationships between their Ea and D2 values (modified Evans-Polanyi-Semenov equation), the specific influence of some physicochemical properties on their thermal decomposition was shown. A new logarithmic relationship was found between the rate constant k, of the unimolecular thermal decomposition of the nitramines studied at 230 °C, and their D values. A fundamental characteristic of this new relationship rests on the equivalency of the primary fission processes in the low-temperature thermal decomposition and on the detonation initiation of the nitramines under study. Both these relationships confirm the problems encountered in the kinetic specification of the thermal decomposition of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12hexaazaisowurtzitane (HNIW, CL-20) and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX). These problems, and also the possible influence of the pre-decomposition states on the thermal decomposition of the nitramines studied, are discussed.

5

Recent Advances in the Study of the Initiation of Energetic Materials Using the Characteristics of Their Thermal Decomposition Part II. Using Simple Differential Thermal Analysis

Zeman S., Yan Q.-L., Elbeih A.

Central European Journal of Energetic Materials

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2014

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Vol. 11, no. 3

395--404

EN

Simple Differential Thermal Analysis (DTA), with evaluation of its output by the Kissinger method, was used in the case of emulsion explosives and, as an advanced application, for several plastic bonded explosives (PBXs). In both of these kinds of explosive the square of their detonation velocities, D2, is used as their performance characteristic. A relationship between the slope of the Kissinger equation, EaT-1, and the D2 values makes it possible to formulate a possible mechanism for the initiation of emulsion explosives. Regarding PBXs, it would seem possible to postulate a change in the detonation chemistry of plastic bonded nitramines, depending on the pressure and temperature in the zone of the detonation wave, particularly in the case of CL-20 fillers. Binders with aromatic building units in their macromolecular structure seem to be less-favoured in terms of their thermal reactivity and performance than the final PBXs. These findings document the advantages of the above-mentioned application of simple DTA.

6

Modelowanie wpływu warunków klimatycznych na szybkość korozji zbrojenia w betonie

Krykowski T., Zybura A.

Cement Wapno Beton

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2014

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R. 18/80, nr 3

166--173

PL

Opracowano oryginalny model wyznaczania czasu inicjacji korozji zbrojenia oraz gęstości prądu korozyjnego, uwzględniający wpływ temperatury i wilgotności środowiska, określający warunki ekspozycji konstrukcji żelbetowej. Przeprowadzone obliczenia, z zastosowaniem nowego modelu, wykazały że zmiany środowiska nie mają większego wpływu na czas inicjacji korozji. Natomiast gęstość prądu korozyjnego, a więc szybkość korozji może różnić się bardzo znacznie, nawet o 100%, od przypadku, w którym założono stałe warunki otoczenia. Odwrotnie grubość otuliny betonowej na prętach zbrojeniowych nie ma wpływu na gęstość prądu korozyjnego, a więc na postęp korozji stali, po jej zapoczątkowaniu.

EN

The original model of the time of the steel reinforcement corrosion initiation in concrete and the density of corrosion current was proposed, taking into account the effect of temperature and humidity of the environment, in which the construction is exposed. The calculation, according to the new model, has shown that the corrosion initiation time is not significantly influenced. However, the density of corrosion current, thus the rate of this process, can differ significantly, even 100%, from the case in which the constant climate conditions was assumed. Contrary the thickness of the concrete cover on steel bars has no influence on the density of corrosion current, thus of corrosion development, after its initiation.

7

Accounts of the new aspects of nitromethane initiation reactivity

Zeman S., Atalar T., Friedl Z., Ju X-H.

Central European Journal of Energetic Materials

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2009

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Vol. 6, nr 1

119-133

EN

A well-known effect of amines, and also of water, on detonation characteristics of nitromethane (NM) is discussed from the point of view of the published knowledge about the study of initiation reactivity of this nitro paraffin. It is documented that bimolecular and higher interactions during the initiation of NM are impossible. The most widespread concepts of the primary steps of this initiation, i.e. formation of aci-NM anion [CH2=NO2]— by intermolecular hydrogen transfer in the neat NM submitted to shock and formation of this anion by action of an amine, have been scrutinized by the DFT B3LYP/cc-pVTZ+ method and evaluated as thermodynamically disadvantageous. Also the 1,3-intramolecular hydrogen shift in the NM molecule was characterized as a higher-barrier process. Two favorable primary mechanisms of fission in the NM initiation and development of its detonation were investigated by DFT B3LYP/cc-pVTZ+ calculations: homolysis of C–NO2 bond in the neat NM and homolysis of N–OH bond in its aci-form. The second mentioned pathway was found to be thermodynamically the most preferable mechanism of fission. Consequently, a detonation wave of NM with admixture of amine or water has a considerably reduced reaction zone length in comparison with the detonation of neat NM. The B3LYP/6-311++G(d,p) calculations of transition states revealed that an admixture of methylamine and/or water influences the conversion of nitromethane to its aci-form, and this effect is more feasible in the case of methylamine rather than water.

8

Use of a Compressed Gas Gun to Investigate Response of Explosives to a Range of Initiation Stimuli

Cartwright M., Lewis A.

Central European Journal of Energetic Materials

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2007

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Vol. 4, nr 4

33-43

EN

Low velocity impacts are a source of explosive accidents. Several different mechanisms may be concurrently responsible for the initiation. Studying the effects of low velocity, comparatively long duration, impacts on energetic materials can assist in the development of explosive safety procedures and Insensitive Munitions. Careful design of the target configuration can eliminate some of the problems associated with the original Steven tests and enable the various mechanisms such as friction, shear and pinch to be isolated from other factors. In the new configuration the impact is delivered to the explosive by a spigot driven into the target by collision from a gun launched sabot. The spigot geometry i.e. flat or hemi-spherically nosed was varied as was the surface roughness and diameter of the spigot. The rate of energy delivery was varied, by varying the mass of the sabot and its velocity. The gun, 50 mm diameter, operated in the normal atmosphere conditions, NAG. Results show that pinch may be the most critical stimulus but also that friction is more significant than shear. Examination of the target debris following an event indicated that for some materials the limited confinement arising during the firing may result in a burn to detonation condition whereas for other materials the confinement was insufficient for the DDT to occur. Further work on the sample perfection and homogeneity are planned.

9

Initiation Strength of Detonators - Air Gap Test Method

Jungová M., Strnad J.

Central European Journal of Energetic Materials

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2006

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Vol. 3, nr 3

79-90

EN

The present paper describes a new method of Air Gap Test used for determination of initiation strength of detonators. Factors influencing initiation strength of detonators are stated. Results of the experiments performed at the Institute of Energetic Materials are summarized.

10

Atomistic Studies of Fundamental Properties and Processes in Energetic Materials: Relevance to Mesoscale Initiation Phenomena

Sewell T. D.

Central European Journal of Energetic Materials

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2006

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Vol. 3, nr 1-2

19-38

EN

Genuine, physics-based understanding of initiation phenomena in plasticbonded explosives (PBXs) requires knowledge of the physics and chemistry at mesoscopic scales that are far larger than can be simulated directly using atomistic detail, yet far smaller than is directly resolvable in practical engineering scale continuum simulations. Initiation is determined by localization phenomena that arise due to the heterogeneous character of most explosive formulations. Indeed, the "average" temperature behind a weak shock is not a useful measure for understanding initiation phenomena; rather, it is the tails of the distributions in temperature, stress, and strain rates, localized to small, spatially distributed volumes in the material (hot spots), that dictate the outcome of a given loading event. Important factors for predicting hot spot formation and subsequent extinction or growth/coalescence include particle size, concentration, morphology, and void content; physical and chemical interactions between grains and binder; thermophysical and mechanical properties of the constituents and interfaces between them; and, of course, the inherent chemical stability of the explosive component(s) in the formulation. We are in the process of computing many of the thermophysical and mechanical properties required for a complete specification of constituent models for use in mesoscale simulations, wherein grains and binder in representative volumes of a PBX are spatially resolved and then studied within a continuum hydrodynamic framework. In addition to calculating specific properties of interest, we have recently undertaken a series of large-scale molecular dynamics simulations of energetic crystals to understand dissipation phenomena in dynamically loaded single- or poly-crystalline samples; for instance, plastic deformation and stress/energy localization mechanisms, phase transitions, and so on. Recent and ongoing work in these areas will be discussed, along with their specific relevance to emerging mesoscale simulation capabilities.

11

Selected problems of fatigue of materials and construction elements

Kłysz S.

Technical Sciences / University of Warmia and Mazury in Olsztyn

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2005

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nr 8

141-164

EN

The study presents a survey of selected fatigue test methods and strength analyses of construction elements. The general characteristics of fatigue strength problems, with a focus on the procedure algorithms employed during strength assessment for the initiation of fatigue cracks and propagation life are given. The results of fatigue tests carried out on two different types of specimens - CCT and SEN - were compared.

PL

Przedstawiono przegląd wybranych metod badań zmęczeniowych i analiz oceny trwałości elementów konstrukcji. Podano ogólną charakterystykę zagadnień wytrzymałości zmęczeniowej, a szczególnie algorytmy postępowania przy ocenie trwałości do zainicjowania pęknięć zmęczeniowych i trwałości propagacyjnej. Porównano wyniki badań zmęczeniowych na dwóch rodzajach próbek - typu CCT i SEN.

12

Study on Primary Step of Initiation Mechanisms of Two Polynitro Arenes

Zeman S., Shu Y., Wang X.

Central European Journal of Energetic Materials

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2005

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Vol. 2, nr 4

47-54

EN

Each one of the 2,6-bis(2,4,6-trinitrophenylamino)-3,5-dinitropyridine (PYX) and 2,4,6-tris(3-methyl-2,4,6-trinitrophenylamino)-1 ,3,5-triazine (TMPM) molecules contains two potential centres of primary fission in its initiation. This fission should be accomplished by migration of the y-hydrogen atom to the oxygen atom of the ortho-nitro group ("trinitrotoluene mechanism"). The morę probable pathways of initiation of the named molecules are estimated from considerations involving the several relationships: (1) between impact sensitivity and the 13C NMR chemical shifts of some polynitro arenas; (2) between Mulliken charges on nitrogen atoms of the primarily reacting nitro group and onsets of thermal decompositions from differential thermal analyses of the said compounds; and, (3) with computations obtained using the DFT-B3LYP/3-21g methods in the GAUSSIAN 98/03 program.

13

Some Notes on the Fundamentals of E.M. Initiation Towards a "Universal Sensitivity Characteristic"?

Pasman H. J., Bouma R., Zarzalis N., Weiss M.

Central European Journal of Energetic Materials

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2005

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Vol. 2, nr 3

55-69

EN

The stimulus needed for initiation of an energetic material is an important quantity to determine for reliable functioning and safe handling. When considering the gamma of impact, friction, spark and heating tests in use one runs into the problem of how to compare results and how to make a prediction for practical situations that an initiation certainly will happen or definitely can be excluded. The way forward is not easy. The initiation process, which in order to be successful, should be followed by sustained propagation, is not simply accessible. This paper tries to produce a contribution by considering the fundamental aspects and to show as an example some simulation results of a gas phase initiation model. Some suggestions are made for making further progress.

14

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.

15

Układ inicjacji próżniowego wyładowania łukowego

Majcher A., Gospodarczyk A., Mrozek M., Przybylski J.

Problemy Eksploatacji

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2004

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nr 4

53-61

PL

Zasadniczym elementem urządzeń dla procesów nakładania warstw przeciwzużyciowych metodą próżniowo-łukową są łukowe źródła plazmy. W źródłach tych konieczne jest inicjowanie wyładowania łukowego. W artykule opisano opracowany i wykonany układ inicjacji próżniowego wyładowania łukowego (MIL) realizujący to zadanie. Określono warunki zapoczątkowania próżniowego wyładowania łukowego. Podano, określone eksperymentalnie, wartości energii koniecznej do zapoczątkowania wyładowania łukowego oraz czynniki determinujące tę wartość. Przedstawiono wyniki eksperymentów weryfikujących układ, potwierdzających poprawność jego funkcjonowania.

EN

Plasma arc sources are fundamental to the processes of antiwear coatings deposition by vacuum arc based method. There is necessary arc initiation in these sources. In the article designed and fabricated system which realize this task was described. The value of energy necessary to arc initiation, obtained by experimental method and the factors which determine this one was given. The results of test experiments that confirmed proper system operation was presented.

16

The effect of solvation on thermal decomposition of 2,2'-azoisobutyronitrile in the acrylonitrile/methyl methacrylate system

Szafko J., Feist W., Babin-Szafko W.

Polimery

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1999

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T. 44, nr 5

319-325

EN

The rate constant of thermal decomposition of 2,2'-azoisobutyronitrile (AIBN), Kd, was studied in acrylonitrile (AN)/methyl methacrylate (MMA) mixtures in relation to mixture composition at 60°C. In pure AN and in pure MMA as solvent (boundary conditions), the values were found to be identical, viz., kd = (7.20 š 0.3) o 10-4 min-1. In AN/MMA mixtures, Kd-values were found to be related to AN/MMA mixture composition. The Kd = F(XA) functional relationship is nonlinear and its graphical course is characterized by a shallow flat minimum that extends over a broad concentration range, 10 to 90 mol % AN. The relationship has been interpreted in terms of the hypothesis of solvation of the initiator (AIBN) molecule by AN and MMA molecules.

PL

Wyznaczono stałą szybkości /Q reakcji rozkładu termicznego 2,2'-azoizobutyronitrylu (AIBN) w mieszaninach monomerów akrylonitryl (AN)/metakrylan metylu (MMA) w pełnym zakresie składu, w temp. 60°C (rys. l-4). W przypadku użycia czystego MMA lub czystego AŃ jako rozpuszczalnika, wartości kj są jednakowe i wynoszą (7,20 š 0,3) o 10-4 min-1. Natomiast w mieszaninach AN/MMA zależność kd od stężenia AŃ (xAN) jest nieliniowa i charakteryzuje się występowaniem płytkiego, płaskiego minimum w szerokim zakresie XAN = 10-90% mol. Interpretując tę zależność, posłużono się hipotezą o solwatacji cząsteczek inicjatora AIBN przez cząsteczki monomerów AŃ i MMA.