EXPLOSIVES- These are substances or their mixtures that, under the influence of external influences (heating, impact, friction, explosion of another substance), decompose very quickly with the release of gases and a large amount of heat.

Explosive mixtures existed long before the appearance of man on Earth. The small (1-2 cm long) orange-blue bombardier beetle Branchynus explodans defends itself from attacks in a very ingenious way. A small bag in his body accumulates a concentrated solution of hydrogen peroxide. At the right time, this solution is quickly mixed with the catalase enzyme. The reaction proceeding at the same time was observed by everyone who treated the cut finger with a pharmacy 3% peroxide solution: the solution literally boils, releasing oxygen bubbles. Simultaneously, the mixture is heated (the thermal effect of the reaction 2H 2 O 2 ® 2H 2 O + O 2 is 190 kJ/mol). In the beetle, simultaneously with this, there is another reaction catalyzed by the enzyme peroxidase: the oxidation of hydroquinone with hydrogen peroxide to benzoquinone (the heat effect of this reaction is more than 200 kJ/mol). The heat released is sufficient to heat the solution to 100°C and even partially evaporate it. The reaction of the beetle is so fast that the caustic mixture, heated to a high temperature, is fired with a loud sound at the enemy. If a jet, the mass of which is only half a gram, hits the skin of a person, it will cause a small burn.

The principle "invented" by the beetle is typical of chemical explosives, in which energy is released due to the formation of strong chemical bonds. In nuclear weapons, energy is released by the fission or fusion of atomic nuclei. An explosion is a very rapid release of energy in a limited volume. In this case, instantaneous heating and expansion of the air occurs, and a shock wave begins to propagate, leading to great destruction. If you blow up dynamite (without a steel shell) on the Moon, where there is no air, the destructive consequences will be immeasurably less than on Earth. The following fact testifies to the need for a very rapid release of energy for an explosion. It is well known that a mixture of hydrogen and chlorine explodes if it is exposed to direct sunlight or if you bring burning magnesium to the flask - this is even written in school textbooks, but if the light is not so bright, the reaction will go quite smoothly, it will stand out that the same energy, but not in a hundredth of a second, but in a few hours, and as a result, the heat will simply dissipate in the surrounding air.

During any exothermic reaction, the released thermal energy heats not only the environment, but also the reactants themselves. This leads to an increase in the reaction rate, which in turn accelerates the release of heat and this further raises the temperature. If the removal of heat to the surrounding space does not keep up with its release, then as a result, the reaction can, as chemists say, “run wild” - the mixture boils and splashes out of the reaction vessel or even explodes if the gases and vapors released do not find a quick exit from the vessel . This is the so-called thermal explosion. Therefore, when carrying out exothermic reactions, chemists carefully monitor the temperature, lowering it if necessary by adding pieces of ice to the flask or placing the vessel in a cooling mixture. It is especially important to be able to calculate the rate of heat release and heat removal for industrial reactors.

Energy is released very quickly in case of detonation. This word (it comes from the Latin detonare - to thunder) means the chemical transformation of an explosive, which is accompanied by the release of energy and the propagation of a wave through the substance at supersonic speed. The chemical reaction is excited by an intense shock wave, which forms the leading edge of the detonation wave. The pressure in the front of the shock wave is tens of thousands of megapascals (hundreds of thousands of atmospheres), which explains the huge destructive effect of such processes. The energy released in the chemical reaction zone continuously maintains high pressure in the shock wave. Detonation occurs in many compounds and their mixtures. For example, tetranitromethane C (NO 2) 4 - a heavy colorless liquid with a pungent odor - distills without an explosion, but its mixtures with many organic compounds detonate with great force. So, during a lecture in one of the German universities in 1919, many students died due to the explosion of a burner, which demonstrated the combustion of a mixture of tetranitromethane with toluene. It turned out that the laboratory assistant, while preparing the mixture, mixed up the mass and volume fractions of the components, and at reagent densities of 1.64 and 0.87 g/cm3, this caused an almost twofold change in the composition of the mixture, which led to the tragedy.

What substances can explode? First of all, these are the so-called endothermic compounds, that is, compounds whose formation from simple substances is accompanied not by the release, but by the absorption of energy. Such substances include, in particular, acetylene, ozone, chlorine oxides, peroxides . Thus, the formation of 1 mole of C 2 H 2 from elements is accompanied by an expenditure of 227 kJ. This means that acetylene should be considered a potentially unstable compound, since the reaction of its decomposition into simple substances C 2 H 2 ® 2C + H 2 is accompanied by the release of very large energy. That is why, unlike many other gases, acetylene is never pumped into cylinders under high pressure - this can lead to an explosion (in cylinders with acetylene, this gas is dissolved in acetone, which is impregnated with a porous carrier).

Acetylides of heavy metals - silver, copper - decompose with an explosion. For the same reason, pure ozone is also very dangerous, the decay of 1 mole of which releases 142 kJ of energy. However, many potentially unstable compounds can be quite stable in practice. An example is ethylene, the reason for the stability of which is a very low rate of decomposition into simple substances.

Historically, the first explosive invented by people was black (aka smoky) gunpowder - a mixture of finely ground sulfur, charcoal and potassium nitrate - potassium nitrate (sodium is not suitable, since it is hygroscopic, that is, damp in air). This invention has claimed millions of human lives over the past centuries. However, gunpowder was invented, it turns out, for other purposes: the ancient Chinese made fireworks with the help of gunpowder more than two thousand years ago. The composition of Chinese gunpowder allowed it to burn but not explode.

The ancient Greeks and Romans did not have saltpeter, so they could not have gunpowder either. Approximately in the 5th c. saltpeter came from India and China to Byzantium, the capital of the Greek Empire. In Byzantium, it was discovered that a mixture of saltpeter with combustible substances burns very intensely and it is impossible to put it out. Why this happens, it became known much later - such mixtures do not need air for combustion: saltpeter itself is a source of oxygen). Combustible mixtures containing saltpeter called "Greek fire" began to be used in military affairs. With their help, in 670 and 718 the ships of the Arab fleet that besieged Constantinople were burned. In the 10th century Byzantium repelled the invasion of the Bulgarians with the help of Greek fire.

Centuries passed, and in medieval Europe, gunpowder was reinvented. It happened in the 13th century. And who was the inventor is unknown. According to one legend, Berthold Schwartz, a monk from Freiburg, ground a mixture of sulfur, charcoal and saltpeter in a heavy metal mortar. An iron ball accidentally fell into the mortar. There was a terrible roar, acrid smoke poured out of the mortar, and a hole formed in the ceiling - it was pierced by a ball that flew out of the mortar at great speed. It became clear what a huge power lurks in the black powder (the word "gunpowder" itself comes from the old Russian "dust" - dust, powder). In 1242 gunpowder was described by the English philosopher and naturalist Roger Bacon. Gunpowder began to be used in military affairs. In 1300 the first cannon was cast, and the first guns soon appeared. The first gunpowder factory in Europe was built in Bavaria in 1340. In the 14th century. firearms began to be used in Russia too: in 1382 Muscovites used it to defend their city from the troops of the Tatar Khan Tokhtamysh.

The invention of gunpowder had a huge impact on world history. With the help of firearms, seas and continents were conquered, civilizations were destroyed, entire nations were destroyed or subjugated. But the discovery of gunpowder also had positive aspects. Easier hunting for wild animals. In 1627, in Banska Stjavica, on the territory of modern Slovakia, gunpowder was first used in mining - to destroy rock in a mine. Thanks to gunpowder, a special science of calculating the movement of nuclei appeared - ballistics. Methods for casting metals for cannons began to improve, new strong alloys were invented and tested. New methods of obtaining gunpowder were also developed - and above all saltpeter.

The number of gunpowder factories grew all over the world. Many varieties of black powder were made on them - for mines, cannons, guns, including hunting ones. Studies have shown that gunpowder has the ability to burn very quickly. The combustion of the most common powder composition is approximately described by the equation 2KNO 3 + S + 3C ® K 2 S + 3CO 2 + N 2 (in addition to sulfide, potassium sulfate K 2 SO 4 is also formed). The specific composition of the products depends on the combustion pressure. D.I. Mendeleev, who studied this issue, pointed out a significant difference in the composition of the solid residue during blank and live shots.

In any case, when burning gunpowder, a large amount of gases is released. If gunpowder is poured onto the ground and set on fire, it will not explode, but simply burn out quickly, but if it burns in a confined space, for example, in a gun cartridge, then the gases released force the bullet out of the cartridge, and it flies out of the muzzle with great speed. In 1893, at the World Exhibition in Chicago, the German industrialist Krupp showed a gun that was loaded with 115 kg of black powder, its 115 kg projectile flew over 20 km in 71 seconds, reaching a height of 6.5 km at its highest point.

Particles of solids formed during the burning of black powder create black smoke, battlefields were sometimes so shrouded in smoke that it obscured the sunlight (in the novel War and Peace described how smoke made it difficult for commanders to control the course of battles). The solid particles formed during the burning of black powder contaminate the channel of a firearm, so the muzzle of a gun or cannon had to be cleaned regularly.

By the end of the 19th century black powder has almost exhausted its capabilities. Chemists knew a lot of explosives, but they were not suitable for shooting: their crushing (blasting) power was such that the barrel would have shattered into pieces even before the projectile or bullet left it. This property is possessed, for example, by lead azide Pb (N 3) 2, mercury fulminate Hg (CNO) 2 - a salt of fulminic (fulminic) acid. These substances are easily exploded by friction and impact, they are used to equip primers and serve to ignite gunpowder.

In 1884, the French engineer Paul Viel invented a new type of gunpowder - pyroxylin. Pyroxylin was obtained as early as 1846 by nitrating cellulose (fiber), but for a long time they could not develop a technology for obtaining a stable and safe gunpowder. Viel, having dissolved pyroxylin in a mixture of alcohol and ether, obtained a pasty mass, which, after pressing and drying, gave excellent gunpowder. Ignited in the air, it burned quietly, and in the cartridge or shell of the projectile it exploded with great force from the detonator. In terms of power, the new gunpowder was much superior to black gunpowder, and did not produce smoke during combustion, which is why it was called smokeless. This gunpowder made it possible to reduce the caliber (inner diameter) of rifles and pistols and thus increase not only the range, but also the accuracy of shooting. In 1889, an even more powerful smokeless powder appeared - nitroglycerin. The great Russian chemist D.I. Mendeleev did a lot to improve smokeless powder. Here is what he himself wrote about it:

“Black smoke powder was found by the Chinese and monks - almost by accident, groping, mechanical mixing, in scientific darkness. Smokeless powder has been discovered in the full light of modern chemical knowledge. It will constitute a new era of military affairs, not because it does not give smoke that obscures the eye, but mainly because, with less weight, it makes it possible to impart speeds of 600, 800 and even 1000 meters per second to bullets and any other projectiles, and at the same time represents all the makings of further improvement - with the help of a scientific study of invisible phenomena that occur during its combustion. Smokeless powder is a new link between the power of countries and their scientific development. For this reason, being one of the warriors of Russian science, in my declining years and strength I did not dare to refuse to analyze the problems of smokeless powder.

The gunpowder created by Mendeleev in 1893 was successfully tested: they were fired from a 12-inch gun, and the inspector of naval artillery, Admiral Makarov, congratulated the scientist on his brilliant victory. With the help of smokeless powder, the firing range was significantly increased. From a huge gun "Big Bertha" weighing 750 tons, the Germans fired at Paris from a distance of 128 km. The initial speed of the projectile was 2 km / s, and its highest point was far in the stratosphere at an altitude of 40 km. During the summer of 1918, more than 300 shells were fired at Paris, but, of course, this shooting had only psychological significance, since there was no need to talk about any accuracy.

Smokeless powder is used not only in firearms, but also in rocket engines (solid rocket fuel). During the Second World War, our army successfully used solid fuel rockets - they were fired by the legendary Katyusha guards mortars.

The product of phenol nitration, trinitrophenol (picric acid), had a similar fate. It was obtained as early as 1771 and was used as a yellow dye. And only at the end of the 19th century. it began to be used to equip grenades, mines, shells called lyddita. The colossal destructive power of this substance, used in the Boer War, is vividly described by Louis Boussinard in an adventure novel. Captain Rip-Head. And from 1902, the safer trinitrotoluene (TNT, tol) began to be used for the same purposes. Tol is widely used in blasting in industry in the form of cast (or pressed) pieces, since this substance can be melted without fear by heating above 80 ° C.

Nitroglycerin, which is very dangerous to handle, has the strongest explosive properties. In 1866, Alfred Nobel managed to "tame" him, who, by mixing nitroglycerin with a non-combustible material, received dynamite. Dynamite was used to dig tunnels and in many other mining operations. In the first year, its use in the construction of tunnels in Prussia saved 12 million gold marks.

Modern explosives must meet many conditions: safety in production and handling, the release of large volumes of gases, cost-effectiveness. The cheapest explosive is a mixture of ammonium nitrate with diesel fuel, its production accounts for 80% of all explosives. And which one is the most powerful? It depends on the power criterion. On the one hand, the detonation velocity is important; wave propagation speed. On the other hand, the density of matter, since the higher it is, the more energy, ceteris paribus, is released per unit volume. So, for the most powerful nitro compounds, both parameters have been improved by 20–25% over more than 100 years, as can be seen from the following table:

Hexogen (1,3,5-trinitro-1,3,5-triazacyclohexane, cyclonite), which has become notorious in recent years, with the addition of paraffin or wax, as well as mixed with other substances (TNT, ammonium nitrate, aluminum) began to be used in 1940. It is used to equip ammunition, and is also part of the ammonites used in rock work.

The most powerful explosive produced (since 1955) on an industrial scale is octogen (1,3,5,7-tetranitro-1,3,5,7-tetraazocyclooctane). HMX is quite resistant to heat, so it is used in blasting in high temperature conditions, for example, in deep wells. A mixture of HMX with TNT (octol) is a component of solid rocket fuels. The absolute record is held by hexanitroisowurtzitane synthesized in the USA in 1990. The shock wave during its explosion propagates 30 times faster than sound

Ilya Leenson

Terminology

The complexity and diversity of the chemistry and technology of explosives, political and military contradictions in the world, the desire to classify any information in this area have led to unstable and diverse formulations of terms.

Industrial Application

Explosives are also widely used in industry for the production of various blasting operations. The annual consumption of explosives in countries with developed industrial production, even in peacetime, is hundreds of thousands of tons. In wartime, the consumption of explosives increases sharply. So, during the 1st World War in the warring countries it amounted to about 5 million tons, and in the 2nd World War it exceeded 10 million tons. The annual use of explosives in the United States in the 1990s was about 2 million tons.

• throwing
  Throwing explosives (gunpowder and rocket propellants) serve as sources of energy for throwing bodies (shells, mines, bullets, etc.) or propelling rockets. Their distinctive feature is the ability to explosive transformation in the form of rapid combustion, but without detonation.
• pyrotechnic
  Pyrotechnic compositions are used to obtain pyrotechnic effects (light, smoke, incendiary, sound, etc.). The main type of explosive transformations of pyrotechnic compositions is combustion.

Throwing explosives (gunpowder) are mainly used as propellant charges for various types of weapons and are intended to give a projectile (torpedo, bullet, etc.) a certain initial speed. Their predominant type of chemical transformation is rapid combustion caused by a beam of fire from the means of ignition. Gunpowder is divided into two groups:

a) smoky

b) smokeless.

Representatives of the first group can serve as black powder, which is a mixture of saltpeter, sulfur and coal, such as artillery and gunpowder, consisting of 75% potassium nitrate, 10% sulfur and 15% coal. The flash point of black powder is 290 - 310 ° C.

The second group includes pyroxylin, nitroglycerin, diglycol and other gunpowders. The flash point of smokeless powders is 180 - 210 ° C.

Pyrotechnic compositions (incendiary, lighting, signal and tracer) used to equip special ammunition are mechanical mixtures of oxidizers and combustible substances. Under normal conditions of use, when burned, they give the corresponding pyrotechnic effect (incendiary, lighting, etc.). Many of these compounds also have explosive properties and under certain conditions can detonate.

According to the method of preparation of charges

• pressed
• cast (explosive alloys)
• patronized

By areas of application

• military
• industrial

• for mining (mining, production of building materials, stripping)
  Industrial explosives for mining according to the conditions of safe use are divided into

• non-safety
• safety

• for construction (dams, canals, pits, road cuts and embankments)
• for seismic exploration
• for the destruction of building structures
• for material processing (explosion welding, explosion hardening, explosion cutting)

• special purpose (for example, means of undocking spacecraft)
• anti-social use (terrorism, hooliganism), often using low-quality substances and artisanal mixtures.
• experimental.

According to the degree of danger

There are various systems for classifying explosives according to the degree of danger. The most famous:

• Globally Harmonized System of Classification and Labeling of Chemicals

• Classification according to the degree of danger in mining;

By itself, the energy of the explosive is small. An explosion of 1 kg of TNT releases 6-8 times less energy than the combustion of 1 kg of coal, but this energy is released during an explosion tens of millions of times faster than during conventional combustion processes. In addition, coal does not contain an oxidizing agent.

see also

Literature

1. Soviet military encyclopedia. M., 1978.
2. Pozdnyakov Z. G., Rossi B. D. Handbook of Industrial Explosives and Explosives. - M.: "Nedra", 1977. - 253 p.
3. Fedoroff, Basil T. et al Enciclopedia of Explosives and Related Items, vol.1-7. - Dover, New Jersey: Picatinny Arsenal, 1960-1975.

Links

• // Encyclopedic Dictionary of Brockhaus and Efron: In 86 volumes (82 volumes and 4 additional). - St. Petersburg. , 1890-1907.

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See what "Explosives" is in other dictionaries:

- (a. explosives, blasting agents; n. Sprengstoffe; f. explosifs; i. explosivos) chem. compounds or mixtures of substances capable, under certain conditions, of extremely fast (explosive) self-propagating chem. transformation with the release of heat ... Geological Encyclopedia

- (Explosive matter) substances that are capable of giving the phenomenon of an explosion due to their chemical transformation into gases or vapors. V. V. are divided into propelling gunpowder, blasting having a crushing effect and initiating to ignite and detonate others ... Marine Dictionary

EXPLOSIVES, a substance that reacts quickly and sharply to certain conditions, with the release of heat, light, sound and shock waves. Chemical explosives are for the most part compounds with a high content… Scientific and technical encyclopedic dictionary

Since the invention of gunpowder, the world race for the most powerful explosives has not stopped. This is true even today, despite the appearance of nuclear weapons.

1 Hexogen is an explosive drug

Back in 1899, for the treatment of inflammation in the urinary tract, the German chemist Hans Genning patented the drug hexogen, an analogue of the well-known hexamine. But soon the doctors lost interest in him due to side intoxication. Only thirty years later it became clear that hexogen turned out to be the most powerful explosive, moreover, more destructive than TNT. A kilogram RDX explosive will produce the same destruction as 1.25 kilograms of TNT.

Specialists in pyrotechnics mainly characterize explosives by explosiveness and brisance. In the first case, one speaks of the volume of gas released during the explosion. Like, the larger it is, the more powerful the explosiveness. Brisance, in turn, depends already on the rate of formation of gases and shows how explosives can crush surrounding materials.

10 grams of RDX emit 480 cubic centimeters of gas during an explosion, while TNT - 285 cubic centimeters. In other words, RDX is 1.7 times more powerful than TNT in explosiveness and 1.26 times more dynamic in blasting.

However, the media most often uses a certain average indicator. For example, the atomic charge "Baby", dropped on August 6, 1945 on the Japanese city of Hiroshima, is estimated at 13-18 kilotons of TNT. Meanwhile, this does not characterize the power of the explosion, but indicates how much TNT is needed to release the same amount of heat as during the indicated nuclear bombardment.

In 1942, the American chemist Bachmann, while conducting experiments with RDX, accidentally discovered a new substance, HMX, in the form of an impurity. He offered his find to the military, but they refused. Meanwhile, a few years later, after it was possible to stabilize the properties of this chemical compound, the Pentagon nevertheless became interested in HMX. True, it was not widely used in its pure form for military purposes, most often in a casting mixture with TNT. This explosive was called "Octolome". It turned out to be 15% more powerful than hexogen. As for its effectiveness, it is believed that one kilogram of HMX will produce as much destruction as four kilograms of TNT.

However, in those years, the production of HMX was 10 times more expensive than the production of RDX, which hindered its production in the Soviet Union. Our generals have calculated that it is better to produce six shells with hexogen than one with octol. That is why the explosion of an ammunition depot in the Vietnamese Quy Ngon in April 1969 cost the Americans so dearly. Then a Pentagon spokesman said that due to the sabotage of the partisans, the damage amounted to 123 million dollars, or about 0.5 billion dollars in current prices.

In the 80s of the last century, after Soviet chemists, including E.Yu. Orlov, developed an efficient and inexpensive technology for the synthesis of HMX, in large volumes it began to be produced in our country.

3 Astrolite - good, but smells bad

In the early 60s of the last century, the American company EXCOA presented a new explosive based on hydrazine, claiming that it was 20 times more powerful than TNT. The Pentagon generals who arrived for the test were knocked off their feet by the terrible smell of an abandoned public toilet. However, they were willing to endure it. However, a number of tests with air bombs filled with astrolite A 1-5 showed that the explosive was only twice as powerful as TNT.

After Pentagon officials rejected this bomb, EXCOA engineers proposed a new version of this explosive already under the ASTRA-PAK brand, moreover, for digging trenches using the directed explosion method. In the commercial, a soldier poured water on the ground in a thin stream, and then detonated the liquid from cover. And a man-sized trench was ready. On its own initiative, EXCOA produced 1000 sets of such explosives and sent them to the Vietnamese front.

In reality, everything ended sadly and anecdotally. The resulting trenches exuded such a disgusting smell that American soldiers sought to leave them at any cost, regardless of orders and danger to life. Those who remained lost consciousness. Unused kits were sent back to the EXCOA office at their own expense.

4 Explosives that kill their own

Along with hexogen and octogen, hard-to-pronounce tetranitropentaerythritol, which is often called PETN, is considered a classic explosive. However, due to its high sensitivity, it has not been widely used. The fact is that for military purposes, it is not so much explosives that are more destructive than others that are important, but those that do not explode from any touch, that is, with low sensitivity.

Americans are especially meticulous about this issue. It was they who developed the NATO standard STANAG 4439 for the sensitivity of explosives that can be used for military purposes. True, this happened after a series of grave incidents, including: the explosion of a warehouse at the American Air Force Base Bien Ho in Vietnam, which cost the lives of 33 technicians; the disaster on board the USS Forrestal, which resulted in damage to 60 aircraft; detonation in the storage of aircraft missiles aboard the aircraft carrier Oriskany (1966), also with numerous casualties.

5 Chinese destroyer

In the 80s of the last century, the substance tricyclic urea was synthesized. It is believed that the first to receive this explosive were the Chinese. Tests showed the enormous destructive power of "urea" - one kilogram of it replaced twenty-two kilograms of TNT.

Experts agree with such conclusions, since the "Chinese destroyer" has the highest density of all known explosives, and at the same time has the highest oxygen ratio. That is, during the explosion, all material is completely burned. By the way, for TNT it is 0.74.

In reality, tricyclic urea is not suitable for military operations, primarily due to poor hydrolytic stability. The very next day, with standard storage, it turns into mucus. However, the Chinese managed to get another "urea" - dinitrourea, which, although worse in explosiveness than the "destroyer", is also one of the most powerful explosives. Today it is produced by the Americans at their three pilot plants.

6 Pyromaniac's Dream - CL-20

The CL-20 explosive is currently positioned as one of the most powerful. In particular, the media, including Russian ones, claim that one kg of CL-20 causes destruction, which requires 20 kg of TNT.

Interestingly, the Pentagon allocated money for the development of the CL-20 only after the American press reported that such explosives had already been made in the USSR. In particular, one of the reports on this topic was called like this: “Perhaps this substance was developed by the Russians at the Zelinsky Institute.”

In reality, as a promising explosive, the Americans considered another explosive, first obtained in the USSR, namely diaminoazoxyfurazan. Along with high power, which significantly exceeds octogen, it has low sensitivity. The only thing holding back its widespread use is the lack of industrial technology.

For most of history, man has used all kinds of edged weapons to destroy his own kind, ranging from a simple stone ax to very advanced and difficult to manufacture metal tools. Approximately in the XI-XII century, guns began to be used in Europe, and thus mankind became acquainted with the most important explosive - black powder.

It was a turning point in military history, although it took another eight centuries or so for firearms to completely replace sharp-edged steel from the battlefield. In parallel with the progress of guns and mortars, explosives developed - and not only gunpowder, but also all kinds of compounds for equipping artillery shells or making land mines. The development of new explosives and explosive devices is actively continuing today.

Dozens of explosives are known today. In addition to military needs, explosives are actively used in mining, in the construction of roads and tunnels. However, before talking about the main groups of explosives, one should mention in more detail the processes occurring during an explosion and understand the principle of operation of explosives (HEs).

Explosives: what is it?

Explosives are a large group of chemical compounds or mixtures that, under the influence of external factors, are capable of a rapid, self-sustaining and uncontrolled reaction with the release of a large amount of energy. Simply put, a chemical explosion is the process of converting the energy of molecular bonds into thermal energy. Usually its result is a large amount of hot gases, which perform mechanical work (crushing, destruction, movement, etc.).

The classification of explosives is quite complex and confusing. Explosives include substances that decompose not only in the process of explosion (detonation), but also slow or rapid combustion. The last group includes gunpowder and various types of pyrotechnic mixtures.

In general, the concepts of "detonation" and "deflagration" (combustion) are key to understanding the processes of a chemical explosion.

Detonation is the rapid (supersonic) propagation of a compression front with an accompanying exothermic reaction in the explosive. In this case, chemical transformations proceed so rapidly and such an amount of thermal energy and gaseous products are released that a shock wave is formed in the substance. Detonation is the process of the most rapid, one might say, avalanche-like involvement of a substance in a chemical explosion reaction.

Deflagration, or combustion, is a type of redox chemical reaction during which its front moves in a substance due to normal heat transfer. Such reactions are well known to all and are often encountered in everyday life.

It is curious that the energy released during the explosion is not so great. For example, during the detonation of 1 kg of TNT, it is released several times less than during the combustion of 1 kg of coal. However, during an explosion, this happens millions of times faster, all the energy is released almost instantly.

It should be noted that the detonation propagation velocity is the most important characteristic of explosives. The higher it is, the more effective the explosive charge.

To start the process of a chemical explosion, it is necessary to influence an external factor, it can be of several types:

• mechanical (prick, impact, friction);
• chemical (the reaction of a substance with an explosive charge);
• external detonation (explosion in the immediate vicinity of explosives);
• thermal (flame, heating, spark).

It should be noted that different types of explosives have different sensitivity to external influences.

Some of them (for example, black powder) respond well to thermal effects, but practically do not respond to mechanical and chemical ones. And to undermine TNT, only a detonation effect is needed. Explosive mercury reacts violently to any external stimulus, and there are some explosives that detonate without any external influence at all. The practical use of such "explosive" explosives is simply impossible.

The main properties of explosives

The main ones are:

• the temperature of the explosion products;
• heat of explosion;
• detonation speed;
• brisance;
• explosiveness.

The last two points should be dealt with separately. The brisance of an explosive is its ability to destroy the environment adjacent to it (rock, metal, wood). This characteristic largely depends on the physical state in which the explosive is located (degree of grinding, density, uniformity). Brisance directly depends on the detonation speed of the explosive - the higher it is, the better the explosive can crush and destroy surrounding objects.

High explosives are commonly used to load artillery shells, aerial bombs, mines, torpedoes, grenades, and other munitions. This type of explosive is less sensitive to external factors, in order to undermine such an explosive charge, an external detonation is necessary. Depending on their destructive power, high explosives are divided into:

• Increased power: hexogen, tetryl, oxygen;
• Medium power: TNT, melinite, plastid;
• Reduced power: Explosives based on ammonium nitrate.

The higher the explosive blast, the better it will destroy the body of a bomb or projectile, give the fragments more energy and create a more powerful shock wave.

An equally important property of explosives is their explosiveness. This is the most general characteristic of any explosive, it shows how destructive this or that explosive is. Explosiveness directly depends on the amount of gases that are formed during the explosion. It should be noted that brisance and explosiveness, as a rule, are not related to each other.

Explosiveness and brisance determine what we call the power or force of the explosion. However, for various purposes, it is necessary to select the appropriate types of explosives. Brisance is very important for shells, mines and air bombs, but for mining, explosives with a significant level of explosiveness are more suitable. In practice, the selection of explosives is much more complicated, and in order to choose the right explosive, all its characteristics should be taken into account.

There is a generally accepted way to determine the power of various explosives. This is the so-called TNT equivalent, when the power of TNT is conventionally taken as a unit. Using this method, it can be calculated that the power of 125 grams of TNT is equal to 100 grams of RDX and 150 grams of ammonite.

Another important characteristic of explosives is their sensitivity. It is determined by the probability of an explosive explosion under the influence of one or another factor. The safety of production and storage of explosives depends on this parameter.

To better show how important this characteristic of an explosive is, it can be said that the Americans have developed a special standard (STANAG 4439) for the sensitivity of explosives. And they had to do this not because of a good life, but after a series of severe accidents: 33 people were killed in an explosion at the Bien Ho American Air Force Base in Vietnam, about 80 aircraft were damaged as a result of explosions on the Forrestal aircraft carrier, as well as after the detonation of air missiles on the aircraft carrier "Oriskany" (1966). So not just powerful explosives are good, but detonating at exactly the right moment - and never again.

All modern explosives are either chemical compounds or mechanical mixtures. The first group includes hexogen, trotyl, nitroglycerin, picric acid. Chemical explosives are usually obtained by nitration of various types of hydrocarbons, which leads to the introduction of nitrogen and oxygen into their molecules. The second group includes ammonium nitrate explosives. Explosives of this type usually contain substances rich in oxygen and carbon. To increase the explosion temperature, metal powders are often added to the mixture: aluminum, beryllium, magnesium.

In addition to all the above properties, any explosive must be chemically resistant and suitable for long-term storage. In the 80s of the last century, the Chinese managed to synthesize the most powerful explosive - tricyclic urea. Its power exceeded TNT twenty times. The problem was that within a few days after being made, the substance decomposed and turned into a slime unsuitable for further use.

Classification of explosives

According to their explosive properties, explosives are divided into:

1. Initiators. They are used to detonate (detonate) other explosives. The main differences of this group of explosives are high sensitivity to initiating factors and high detonation velocity. This group includes: mercury fulminate, diazodinitrophenol, lead trinitroresorcinate and others. As a rule, these compounds are used in igniter caps, ignition tubes, detonator caps, squibs, self-liquidators;
2. High explosives. This type of explosive has a significant level of brisance and is used as the main charge for the vast majority of ammunition. These powerful explosives differ in their chemical composition (N-nitramines, nitrates, other nitro compounds). Sometimes they are used in the form of various mixtures. High explosives are also actively used in mining, tunneling, and other engineering work;
3. Throwable explosives. They are a source of energy for throwing shells, mines, bullets, grenades, as well as for the movement of rockets. This class of explosives includes gunpowder and various types of rocket fuel;
4. Pyrotechnic compositions. Used to equip special ammunition. When burned, they produce a specific effect: lighting, signal, incendiary.

Explosives are also divided according to their physical state into:

1. Liquid. For example, nitroglycol, nitroglycerin, ethyl nitrate. There are also various liquid mixtures of explosives (panclastite, Sprengel explosives);
2. gaseous;
3. Gel-like. If you dissolve nitrocellulose in nitroglycerin, you get the so-called explosive jelly. It is a highly unstable but rather powerful explosive gel-like substance. It was loved to be used by Russian revolutionary terrorists at the end of the 19th century;
4. Suspensions. Quite an extensive group of explosives, which are currently used for industrial purposes. There are various types of explosive suspensions in which the explosive or oxidizing agent is a liquid medium;
5. Emulsion explosives. A very popular type of VV these days. Often used in construction or mining operations;
6. Solid. The most common group of V.V. It includes almost all explosives used in military affairs. They can be monolithic (TNT), granular or powdered (RDX);
7. Plastic. This group of explosives has plasticity. Such explosives are more expensive than conventional ones, so they are rarely used to equip ammunition. A typical representative of this group is the plastid (or plastitis). It is often used during sabotage to undermine structures. According to its composition, plastids are a mixture of hexogen and some kind of plasticizer;
8. Elastic.

A bit of VV history

The first explosive that was invented by mankind was black powder. It is believed that it was invented in China as early as the 7th century AD. However, reliable evidence for this has not yet been found. In general, many myths and obviously fantastic stories have been created around gunpowder and the first attempts to use it.

There are ancient Chinese texts that describe mixtures similar in composition to black smoke powder. They were used as medicines, as well as for pyrotechnic shows. In addition, there are numerous sources claiming that in the following centuries, the Chinese actively used gunpowder to produce rockets, mines, grenades, and even flamethrowers. True, illustrations of some types of these ancient firearms cast doubt on the possibility of its practical application.

Even before gunpowder, “Greek fire” began to be used in Europe - a combustible explosive, the recipe of which, unfortunately, has not survived to this day. "Greek fire" was a flammable mixture, which not only was not extinguished by water, but even became even more flammable in contact with it. This explosive was invented by the Byzantines, they actively used the "Greek fire" both on land and in sea battles, and kept its recipe in the strictest confidence. Modern experts believe that this mixture included oil, tar, sulfur and quicklime.

Gunpowder first appeared in Europe around the middle of the 13th century, and it is still unknown how exactly it got to the continent. Among the European inventors of gunpowder, the names of the monk Berthold Schwartz and the English scientist Roger Bacon are often mentioned, although there is no consensus among historians. According to one version, gunpowder, invented in China, came to Europe through India and the Middle East. One way or another, already in the 13th century, Europeans knew about gunpowder and even tried to use this crystalline explosive for mines and primitive firearms.

For many centuries, gunpowder remained the only type of explosive that people knew and used. Only at the turn of the XVIII-XIX centuries, thanks to the development of chemistry and other natural sciences, the development of explosives reached new heights.

At the end of the 18th century, thanks to the French chemists Lavoisier and Berthollet, the so-called chlorate powder appeared. At the same time, “explosive silver” was invented, as well as picric acid, which in the future began to be used to equip artillery shells.

In 1799, the English chemist Howard discovered "explosive mercury", which is still used in capsules as an initiating explosive. At the beginning of the 19th century, pyroxylin was obtained - an explosive that could not only equip shells, but also make smokeless powder from it. dynamite. This is a powerful explosive, but it is highly sensitive. During the First World War, they tried to equip shells with dynamite, but this idea was quickly abandoned. Dynamite was used in mining for a long time, but these explosives have not been produced for a long time.

In 1863, German scientists discovered TNT, and in 1891, industrial production of this explosive began in Germany. In 1897, the German chemist Lenze synthesized hexogen, one of the most powerful and common explosives today.

The development of new explosives and explosive devices continued throughout the past century, and research in this direction is still going on today.

The Pentagon received a new explosive based on hydrazine, which was allegedly 20 times more powerful than TNT. However, this explosive also had one tangible minus - the absolutely vile smell of an abandoned station toilet. The test showed that the power of the new substance exceeds TNT by only 2-3 times, and they decided to refuse to use it. After that, EXCOA proposed another way to use the explosive: to make trenches with it.

The substance was poured on the ground in a thin stream, and then exploded. Thus, in a matter of seconds, it was possible to get a trench of a full profile without any extra effort. Several sets of explosives were sent to Vietnam for combat testing. The end of this story was funny: the trenches obtained with the help of the explosion had such a disgusting smell that the soldiers refused to be in them.

In the late 80s, the Americans developed a new explosive - CL-20. According to some media reports, its power is almost twenty times higher than TNT. However, due to its high price ($ 1,300 per 1 kg), large-scale production of the new explosive was never launched.

Terminology

The complexity and diversity of the chemistry and technology of explosives, political and military contradictions in the world, the desire to classify any information in this area have led to unstable and diverse formulations of terms.

Industrial Application

Explosives are also widely used in industry for the production of various blasting operations. The annual consumption of explosives in countries with developed industrial production, even in peacetime, is hundreds of thousands of tons. In wartime, the consumption of explosives increases sharply. So, during the 1st World War in the warring countries it amounted to about 5 million tons, and in the 2nd World War it exceeded 10 million tons. The annual use of explosives in the United States in the 1990s was about 2 million tons.

• throwing
  Throwing explosives (gunpowder and rocket propellants) serve as sources of energy for throwing bodies (shells, mines, bullets, etc.) or propelling rockets. Their distinctive feature is the ability to explosive transformation in the form of rapid combustion, but without detonation.
• pyrotechnic
  Pyrotechnic compositions are used to obtain pyrotechnic effects (light, smoke, incendiary, sound, etc.). The main type of explosive transformations of pyrotechnic compositions is combustion.

Throwing explosives (gunpowder) are mainly used as propellant charges for various types of weapons and are intended to give a projectile (torpedo, bullet, etc.) a certain initial speed. Their predominant type of chemical transformation is rapid combustion caused by a beam of fire from the means of ignition. Gunpowder is divided into two groups:

a) smoky

b) smokeless.

Representatives of the first group can serve as black powder, which is a mixture of saltpeter, sulfur and coal, such as artillery and gunpowder, consisting of 75% potassium nitrate, 10% sulfur and 15% coal. The flash point of black powder is 290 - 310 ° C.

The second group includes pyroxylin, nitroglycerin, diglycol and other gunpowders. The flash point of smokeless powders is 180 - 210 ° C.

Pyrotechnic compositions (incendiary, lighting, signal and tracer) used to equip special ammunition are mechanical mixtures of oxidizers and combustible substances. Under normal conditions of use, when burned, they give the corresponding pyrotechnic effect (incendiary, lighting, etc.). Many of these compounds also have explosive properties and under certain conditions can detonate.

According to the method of preparation of charges

• pressed
• cast (explosive alloys)
• patronized

By areas of application

• military
• industrial

• for mining (mining, production of building materials, stripping)
  Industrial explosives for mining according to the conditions of safe use are divided into

• non-safety
• safety

• for construction (dams, canals, pits, road cuts and embankments)
• for seismic exploration
• for the destruction of building structures
• for material processing (explosion welding, explosion hardening, explosion cutting)

• special purpose (for example, means of undocking spacecraft)
• anti-social use (terrorism, hooliganism), often using low-quality substances and artisanal mixtures.
• experimental.

According to the degree of danger

There are various systems for classifying explosives according to the degree of danger. The most famous:

• Globally Harmonized System of Classification and Labeling of Chemicals

• Classification according to the degree of danger in mining;

By itself, the energy of the explosive is small. An explosion of 1 kg of TNT releases 6-8 times less energy than the combustion of 1 kg of coal, but this energy is released during an explosion tens of millions of times faster than during conventional combustion processes. In addition, coal does not contain an oxidizing agent.

see also

Literature

1. Soviet military encyclopedia. M., 1978.
2. Pozdnyakov Z. G., Rossi B. D. Handbook of Industrial Explosives and Explosives. - M.: "Nedra", 1977. - 253 p.
3. Fedoroff, Basil T. et al Enciclopedia of Explosives and Related Items, vol.1-7. - Dover, New Jersey: Picatinny Arsenal, 1960-1975.

Links

• // Encyclopedic Dictionary of Brockhaus and Efron: In 86 volumes (82 volumes and 4 additional). - St. Petersburg. , 1890-1907.

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• New Wave (series)
• Rucker, Rudy

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