An explosion is an extremely fast process of converting an explosive into a highly heated and compressed gas, which, with the same rapid expansion, performs the mechanical work of moving, crushing, ejecting and destroying.
Explosives are chemical compounds and mixtures that, with a certain type of external influence, begin to actively generate heat and form heated gases in large volumes.
Explosions are generally similar to the burning of coal, firewood and other common combustible substances. The difference is only in the burning rate - in the explosion it occurs in a split second. From here, two main types of transformation of explosions can be derived:
- Combustion, in which energy is transferred from one layer of a substance to another due to thermal conductivity. An example of such a substance is gunpowder.
- Detonation, in which there is a rapid expansion of the resulting gases. The speed of the shock wave can reach the speed of sound. Similar explosives: TNT, RDX, ammonite.
To start the explosion process, it is necessary to carry out external action on the explosive compound. There are several main modes of exposure:
- mechanical - shock, friction, injection;
- chemical - a chemical reaction of an explosive to an additional substance in a charge;
- thermal - spark, heating, ignition;
- detonation - the implementation of the explosion of one chemical compound next to another.
Sensitive classification of explosives
Initiators - have a high sensitivity and have a detonating effect. Such substances for safety are placed in insulated devices - capsule, fuse, detonator capsule.
High -explosive - are used for mines, shells, bombs, missiles, etc. Depending on the power, they are divided into explosives of high power (hexogen, tetryl), normal power (melinite, TNT, plastite) and low power (ammonium nitrate and its various mixtures).
Substances of high 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 power of the explosion or as an intermediate detonator.
Throwing - these are different types of gunpowder, pyrotechnic mixtures, lighting shells, mines, air bombs, flares.
All explosive substances are characterized by the speed of detonation, the heat of the explosive transformation, sensitivity, chemical resistance, high explosiveness, brisance, density, working time, normal state of aggregation.
The most basic properties are brisance and high explosiveness.
Brisance is the ability to crush and destroy objects. Brisance depends on how quickly gases form during an explosion. The higher this property, the better explosives are suitable for mines, shells, bombs, because during the explosion the shell of the shell will be qualitatively fragmented, and the fragments will receive the highest speed and shock wave. The speed of detonation is also directly related to brisance.
Explosiveness - an indicator of the ability to destroy and throw objects from a given area of the explosion. In essence, this is the performance of an explosive. The amount of gas that is released during the explosion and determines the amount of explosiveness.
Different explosives are used for different needs. For work in mines and pits, crushing ice in rivers and oceans, substances with the highest explosiveness are necessary, and brisance can be any. For example, it may be ammonite. For the production of shells, on the contrary, use substances with high brisance and relatively low explosiveness - such as plastid.