Properties of explosives reported herein are measurable physical attributes typical of a single crystal of an explosive material. Chemical Composition, Density, Crystal Hardness, Auto Ignition Temperature, Critical Temperature, Melt Point, Decomposition Temperature, Gas Volume, Temperature of Detonation, Vacuum Stability, Hygroscopicity, Heat of Combustion, Heat of Reaction, Heat of Formation, Heat of Products of Detonation are categorized as properties of an explosive. The term properties shall mean to include explosive characteristics in this manuscript.
The characteristic of an explosive is an attribute measured as a performance value after or during the chemical reaction. Detonation Velocity, Detonation Pressure, Velocity of Detonation Formulae, Shock Sensitivity, Laser Initiation Sensitivity, TNT Equivalency, Brisance, Impact and Friction are categorized as characteristics.
Compositions or mixtures of materials, which are capable of undergoing exothermic chemical reaction at extremely, fast rates to produce gaseous and/or solid reaction products at high pressure and temperature.
High Explosives (36)
High explosives are those in which the chemical reaction, which has been initiated by heat or shock, will propagate at detonation velocities. The result simulates an instantaneous release of the products of explosion. This is termed detonation, or high-order explosion, to differentiate it from low-order explosions, such as the rapid combustion of pyrotechnics and propellants. The products of combustion of high explosives produce extremely high temperatures (e.g. RDX 3600°K (8)), large quantities of gas and some solids. High explosives can be controlled to deflagrate and as such can be used as propellants.
If the propagation velocity of the reaction wave is greater than the velocity of sound in the unreacted material, the wave is said to be a detonation wave and its velocity of propagation is called detonation velocity. The mechanism of detonation is not definitely known, although various hypotheses have been advanced to account for the phenomenon. It is generally agreed that the energy responsible for the extremely rapid decomposition is propagated through an explosive in the form of a mechanical or shock wave, somewhat similar to a sound wave. The wave may be initiated by mechanical or thermal shock sufficient to cause hydrodynamic compression of the first increment or layer of the charge. The energy liberated reinforces the applied shock so that a self-sustaining shock wave is transmitted at high velocity throughout the explosive preceding the reaction zone. Thus, high explosives are characterized essentially by their rapid rate of decomposition when initiated, and by the resultant high rate of energy release.
The speed of the detonation wave, or the velocity of detonation, varies considerably in the various explosives, and may vary in a given explosive under different conditions. For example, under similar conditions of confinement, trinitrotoluene (TNT) and nitroglycerin detonate at rates of 6,800 and 8,400 meters per second, respectively. The degree of confinement will affect these rates somewhat, but not to the same extent as in the low explosives.
Low Explosives (36)
There are two categories of low explosives, pyrotechnics and propellants. Both have chemical reactions, which deflagrate
If the propagation velocity is less than the velocity of sound in the unreacted material, the reaction is said to be a deflagration and its velocity of propagation is referred to as burn rate.
A pyrotechnic is a mixture of ingredients of fuel and oxidant (e.g. BKNO3) producing a chemical reaction occurring at a burn rate typically less than 1000 meters per sec (m/s). The reaction does not reach sonic velocities in the unreacted material; therefore, does not produce a detonation. However, under very specific conditions; some pyrotechnics can be made to detonate. The products of combustion primarily produce very hot burning solid particles leaving considerable solid residue behind. There is very little gas generated by pyrotechnics. Pyrotechnics are generally used to produce heat and color in the form of light and smoke.
A propellant can be a compound or a mixture of a pyrotechnic material and high explosive (e.g. Ammonium Perchlorate and HMX) producing a chemical reaction (burn rate) typically less than 1000 m/s, and in rocket propellants often measured in centimeters per second. The reaction does not reach sonic velocities in the unreacted material therefore, does not produce a detonation. Propellants are designed for controlled burning rates producing large quantities of gas at elevated temperature and pressure. However, under very specific conditions, propellants can be made to detonate.