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Explosives - basic concepts, application, classification

The explosion is an extremely fast process of converting an explosive into a highly heated and compressed gas, which, with the same rapid expansion, performs mechanical work of moving, crushing, ejecting and destroying.

Explosives are chemical compounds and mixtures that, under a certain form of external action, begin to actively release heat and form heated gases in a large volume.

Explosions in general are similar to the burning of coal, firewood and other common combustible substances. The difference is only in the burning speed - in the explosion it takes place in a fraction of a second. From here it is possible to deduce two basic types of transformation of explosions:

  1. Combustion, in which energy is transferred from one layer of matter to another due to thermal conductivity. An example of such a substance is gunpowder.
  2. Detonation, in which there is a rapid expansion of the gases formed. The velocity of a shock blast wave can thus reach the speed of sound. Similar explosives: TNT, hexogen, ammonite.

To start the explosion process, it is necessary to carry out an external action on the explosive compound. There are several main ways to influence:

  • Mechanical - impact, rubbing, pricking;
  • Chemical - the chemical reaction of an explosive to an additional substance in a charge;
  • Thermal - spark, heating, ignition;
  • Detonation - the explosion of one chemical compound next to the other.

Classification of explosives by sensitivity

Initiate - have high sensitivity and have a detonating effect. Such substances for safety are placed in isolated devices - a primer, a fuse, a detonator cap.

Brigant - serve for mines, shells, bombs, missiles, etc. Divided according to the power for explosives of high power (hexogen, tetryl), normal power (melinite, TNT, plastic) and reduced power (ammonium nitrate and various mixtures thereof).

Substances of increased power are often used in a mixture with phlegmatizers, which reduce their sensitivity to external influences. They can also be used in combination with other substances to increase the explosive power or as an intermediate detonator.

Thrown - these are different types of gunpowder, pyrotechnic mixtures, lighting projectiles, mines, bombs, flares.

All explosive substances are characterized by the speed of detonation, the heat of explosive transformation, sensitivity, chemical resistance, fugacity, breeziness, density, duration of serviceability, normal aggregate state.

The most basic properties in this case are brisant and high explosive.

Brisance is the ability to crush and destroy objects. Brisance depends on how quickly gases form in the explosion. The higher this property, the better the explosives are suitable for mines, shells, bombs, since during the explosion the shell of the shell will be crushed qualitatively, and the fragments will get the highest velocity and shock wave. The speed of detonation is also directly related to breeziness.

Fugacity is an indicator of the ability to destroy and throw objects from a given area of an explosion. In fact, this is the working capacity of the explosive. The amount of gas that is released during the explosion and determines the amount of fugacity.

Different explosives are used for different needs. For work in mines and pits, crushing ice in rivers and oceans, substances with maximum fugacity are necessary, and brisance can be any. For example, it can be ammonite. For the production of shells, on the contrary, they use substances with high breeziness and relatively low fugacity - such as plastids.

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