Decomposition deflagrating explosives

On DSC examination it exhibits a large decomposition exotherm at 200-250°C, and is a sensitive detonating and deflagrating explosive. 

Combustion and Thermal Decomposition of Explosives. See K.K. Andreev, Explosiv-Stoffe 10(10), 203-12(1962) CA 58, 3263 (1963). This paper is also listed in this Section under Detonation (or Explosion), Development (or Transition) from Combustion (or Burning) or from Deflagration... 

Sample confinement apparently represents one external boundary condition that directly influences the predominant HMX physical state present during a given energetic process or event this in turn, dictates the rate—controlling mechanistic step. It appears there is a mechanistic correlation with the KDIE-determined rate-controlling steps observed in the ambient pressure, slow thermochemical decomposition process with both the rapid pyrolytic decomposition/deflagration process and the thermal explosion event. TUs causes one to wonder if a correlation exists between the high pressure combustion event and the ambient pressure thermochemical decomposition process. 

The pressure developed by decomposition of acetylene in a closed container depends not only on the initial pressure (or more precisely, density), but also on whether the flame propagates as a deflagration or a detonation, and on the length of the container. For acetylene at room temperature and pressure, the calculated explosion pressure ratio, / initial > deflagration and ca 20 for detonation (at the Chapman-Jouguet plane). At 800 kPa (7.93... 

While this book does not cover shock-sensitive powders, such as primary explosives, UN-DOT Class 4.1 Flammable Solids are within its scope. These include thermally unstable powders that can both deflagrate in an oxidant and decompose in bulk. Examples include some nitrogen blowing agents. Should ignition occur at any point, a propagating decomposition... 

Fabiano et al. (1999) describe an explosion in the loading section of an Italian acetylene production plant in which the installed flame arresters did not stop a detonation. The arresters were deflagration type and the arrester elements were vessels packed with silica gel and aluminum plates (Fabiano 1999). It was concluded that the flame arresters used were not suitable for dealing safely with the excess pressures resulting from an acetylene decomposition, and may not have been in the proper location to stop the detonation. 

Silver acetylide decomposition was studied [679] by X-ray diffraction and microscopic measurements and, although the a—time relationship was not established, comparisons of intensities of diffraction lines enabled the value of E to be estimated (170 kj mole 1). The rate-limiting step is believed to involve electron transfer and explosive properties of this compound are attributed to accumulation of solid products which catalyze the decomposition (rather than to thermal deflagration). 

These substances decompose rapidly to produce large volumes of gas. They are substances not classified as deflagrating or detonating explosives but exhibit violent decomposition when subject to heat. 

Deflagration. In high explosives, a relatively slow decomposition accompanied by fumes but not normally by flame. 

Violence of reaction depends on concentration of acid and scale and proportion of reactants. The following observations were made with additions to 2-3 drops of ca. 90% acid. Nickel powder, becomes violent mercury, colloidal silver and thallium powder readily cause explosions zinc powder causes a violent explosion immediately. Iron powder is ineffective alone, but a trace of manganese dioxide promotes deflagration. Barium peroxide, copper(I) oxide, impure chromium trioxide, iridium dioxide, lead dioxide, manganese dioxide and vanadium pentoxide all cause violent decomposition, sometimes accelerating to explosion. Lead(II) oxide, lead(II),(IV) oxide and sodium peroxide all cause an immediate violent explosion. 

The self-heating and decomposition of the explosive and aqueous alkali was studied by DSC in a sealed capsule and in a larger scale furnace test. A rapid exothermic decomposition reaction can be initiated at 100°C or below, and may lead to spontaneous ignition and then deflagration or detonation. 

McPherson, J. B. et al., J. Agric. Food Chem., 1956, 4, 42-49 Overheating during removal of solvent by distillation from a pilot batch of methyl parathion led to explosive decomposition, and the course of the 2-stage decomposition was studied. A 1.5 g sample immersed at 270°C decomposes after an induction period of 54 s and the residue later deflagrates, but a 5 g sample deflagrates during the initial decomposition. 

In view of the ready commercial availability and apparent stability of the hexahy-drate, it is probable that the earlier report of explosion on impact, and deflagration on rapid heating [1] referred to the material produced by partial dehydration at 100°C, rather than the hexahydrate [2], The caked crystalline hydrated salt, prepared from aqueous perchloric acid and excess cobalt carbonate with subsequent heated evaporation, exploded violently when placed in a mortar and tapped gently to break up the crystalline mass, when a nearby dish of the salt also exploded [3]. Subsequent investigation revealed the probable cause as heating the solid stable hexahydrate to a temperature ( 150°C) at which partial loss of water produced a lower and endothermic hydrate (possibly a trihydrate) capable of explosive decomposition. This hazard may also exist for other hydrated metal perchlorates, and general caution is urged [4,5],... 

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