Explosives phases

Dale, C. B., "Hazard Classification of Explosives for Transportation—Non-solid Explosives Phase III," Naval Ordnance Station, Report No. DOT/RSPA/MTB-78/2 (1978). 

The explosive phenomena produced by contact of liquefied gases with water were studied. Chlorodifluoromethane produced explosions when the liquid-water temperature differential exceeded 92°C, and propene did so at differentials of 96-109°C. Liquid propane did, but ethylene did not, produce explosions under the conditions studied [1], The previous literature on superheated vapour explosions has been critically reviewed, and new experimental work shows the phenomenon to be more widespread than had been thought previously. The explosions may be quite violent, and mixtures of liquefied gases may produce overpressures above 7 bar [2], Alternative explanations involve detonation driven by phase changes [3,4] and do not involve chemical reactions. Explosive phase transitions from superheated liquid to vapour have also been induced in chlorodifluoromethane by 1.0 J pulsed ruby laser irradiation. Metastable superheated states (of 25°C) achieved lasted some 50 ms, the expected detonation pressure being 4-5 bar [5], See LIQUEFIED NATURAL GAS, SUPERHEATED LIQUIDS, VAPOUR EXPLOSIONS... 

These stars have been of central concern in a myriad of observational and theoretical works. No wonder They indeed play a key role in many chapters of astrophysics. In particular, they influence the physical and chemical states of their circumstellar environments or of the interstellar medium through their intense radiation and mass losses during their non-explosive phases of evolution, and even more so, as a result of their final supernova explosions. They may act as triggers of star formation, are essential agents of the evolution of the nuclidic content of the galaxies, accelerate particles to cosmic ray energies, and leave neutron stars or black holes at the end of their evolution. They are also the progenitors of certain 7-ray bursts. 

The RER+ carcinogenesis process is thus divided up into two clearly distinct evolutive phases (1) a preliminary phase concerning normal or nearly normal cells in which the acquired mutations necessary to initiate a RER+ carcinogenesis are paradoxically counterselected mainly because of apoptosis and possibly because of senescence and (2) an explosive phase that takes place when the RER hypermutator state is no longer counterselective. 

The principle of heat-flux calorimetry is illustrated with a schematic of a classical DTA in Appendix 9. Accuracies of heat measurements by DSC range from 10% to 0.1%. Temperature can be measured to 0.1 K. Typical heating rates vary between 0.1 and 200 K min. Sample masses can be between 0.05 and 100 mg. The smaller masses are suitable for large heat effects, such as chemical reacdons (explosions), phase transidons, or when fast kinetics is studied. The larger masses are necessary for assessment of smaller heat effects as in studies of heat capacity or glass transitions. Sensitivities are hard to estimate, but effects as small as 1.0 pi s are observable. 

Flock, R.A. Vapor Explosions in a Superheated Liquid. Ph.D. Dissertation, Washington State University 1986. Also Flock, R.A. Fowles, G.R. Explosive Phase Transitions in Superheated Freon, Shock Waves in Condensed Matter, 1983, p. 273. Asay, J.R. Graham, R.A. Straub, G. K. (eds.). Elsevier Science Publishers B.V. 1984. 

The above-mentioned phase transitions conform to the Le Chatelier principle, the sample volume decreasing under high pressure. They are not basically different Irom those observed in the static method, under conditions of thermodynamic equilibrium. There is, however, a class of anomalous phase transitions, which occur only in dynamic experiments and in which the shock compression gives rise to lower densities. The first of such phases was obtained in 1965 by shock treatment of the turbostratic BN [224] the new phase differed from both the graphite-Uke (/i-BN) like (c-BN) polymorphs of boron nitride and was named E-BN (E standing for the explosion phase ). Later, it appeared that the lattice parameters of E-BN are nearly identical to one of the phases of fullerene Ceo [225, 226], viz. a = 11.14, ft = 8.06, c = 7.40 A for E-BN, cf. a= 11.16, = 8.17, c = 7.58 A for Qo, with similar densities of 2.50 g/cm. Thus, the BN-fullerene was obtained by explosion (though not recognized as such) some 25 years before the carbon fuUerene was identified. Later on. 

Chapter 3 Explosives Dehnition of Explosion Categories of Explosions Phases of Explosions Mechanical Overpressure Explosions Mechanical/Chemical Explosions Chemical Explosions Dust Explosions Nuclear Explosions Components of an Explosion Types of Explosives... 

It can be noted that most of the amplification has occurred in the last 30 seconds of this stage, which is only about 10% of the total duration of the stage. This also confirms the theoretical predictions that the amplification is slow in the beginning, whereby the surface fluctuations get arranged on a dominant wavelength, but later enters a nonlinear explosive phase of growth, consistent with an exponential increase of the amplitude. 

CowsER, K.E., Kaye, S.V., Rohwer, P.S., Snyder, W.S. and Struxness, E.G. (1967). Dose Estimation Studies Related to Proposed Construction of an Atlantic-Pacific Interoceank Canal with Nuclear Explosives, Phase I, Report No. ORNL-4101 (Oak Ridge National Laboratory, Oak Ridge, Tennessee). 

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