Explosive material

Explosive material

Overview
An explosive material, also called an explosive, is a reactive substance that contains a great amount of potential energy that can produce an explosion
Explosion
An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. An explosion creates a shock wave. If the shock wave is a supersonic detonation, then the source of the blast is called a "high explosive"...

 if released suddenly, usually accompanied by the production of light
Light
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...

, heat
Heat
In physics and thermodynamics, heat is energy transferred from one body, region, or thermodynamic system to another due to thermal contact or thermal radiation when the systems are at different temperatures. It is often described as one of the fundamental processes of energy transfer between...

, sound
Sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...

, and pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...

. An explosive charge is a measured quantity of explosive material.

This potential energy stored in an explosive material may be
  • chemical energy
    Chemical energy
    Chemical energy is the potential of a chemical substance to undergo a transformation through a chemical reaction or, to transform other chemical substances...

    , such as nitroglycerine or grain dust
  • pressurized
    Pressure
    Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...

     compressed gas
    Gas compressor
    A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume.Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas...

    , such as a gas cylinder
    Gas cylinder
    A gas cylinder is a pressure vessel used to store gases at above atmospheric pressure. High pressure gas cylinders are also called bottles. Although they are sometimes colloquially called "tanks", this is technically incorrect, as a tank is a vessel used to store liquids at ambient pressure and...

     or aerosol can
  • nuclear
    Nuclear weapon
    A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...

    , such as fissile
    Fissile
    In nuclear engineering, a fissile material is one that is capable of sustaining a chain reaction of nuclear fission. By definition, fissile materials can sustain a chain reaction with neutrons of any energy. The predominant neutron energy may be typified by either slow neutrons or fast neutrons...

     isotope
    Isotope
    Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...

    s of uranium-235
    Uranium-235
    - References :* .* DOE Fundamentals handbook: Nuclear Physics and Reactor theory , .* A piece of U-235 the size of a grain of rice can produce energy equal to that contained in three tons of coal or fourteen barrels of oil. -External links:* * * one of the earliest articles on U-235 for the...

     and plutonium-239
    Plutonium-239
    Plutonium-239 is an isotope of plutonium. Plutonium-239 is the primary fissile isotope used for the production of nuclear weapons, although uranium-235 has also been used and is currently the secondary isotope. Plutonium-239 is also one of the three main isotopes demonstrated usable as fuel in...



Explosive materials may be categorized by the speed at which they expand.
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Encyclopedia
An explosive material, also called an explosive, is a reactive substance that contains a great amount of potential energy that can produce an explosion
Explosion
An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. An explosion creates a shock wave. If the shock wave is a supersonic detonation, then the source of the blast is called a "high explosive"...

 if released suddenly, usually accompanied by the production of light
Light
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...

, heat
Heat
In physics and thermodynamics, heat is energy transferred from one body, region, or thermodynamic system to another due to thermal contact or thermal radiation when the systems are at different temperatures. It is often described as one of the fundamental processes of energy transfer between...

, sound
Sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...

, and pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...

. An explosive charge is a measured quantity of explosive material.

This potential energy stored in an explosive material may be
  • chemical energy
    Chemical energy
    Chemical energy is the potential of a chemical substance to undergo a transformation through a chemical reaction or, to transform other chemical substances...

    , such as nitroglycerine or grain dust
  • pressurized
    Pressure
    Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...

     compressed gas
    Gas compressor
    A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume.Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas...

    , such as a gas cylinder
    Gas cylinder
    A gas cylinder is a pressure vessel used to store gases at above atmospheric pressure. High pressure gas cylinders are also called bottles. Although they are sometimes colloquially called "tanks", this is technically incorrect, as a tank is a vessel used to store liquids at ambient pressure and...

     or aerosol can
  • nuclear
    Nuclear weapon
    A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...

    , such as fissile
    Fissile
    In nuclear engineering, a fissile material is one that is capable of sustaining a chain reaction of nuclear fission. By definition, fissile materials can sustain a chain reaction with neutrons of any energy. The predominant neutron energy may be typified by either slow neutrons or fast neutrons...

     isotope
    Isotope
    Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...

    s of uranium-235
    Uranium-235
    - References :* .* DOE Fundamentals handbook: Nuclear Physics and Reactor theory , .* A piece of U-235 the size of a grain of rice can produce energy equal to that contained in three tons of coal or fourteen barrels of oil. -External links:* * * one of the earliest articles on U-235 for the...

     and plutonium-239
    Plutonium-239
    Plutonium-239 is an isotope of plutonium. Plutonium-239 is the primary fissile isotope used for the production of nuclear weapons, although uranium-235 has also been used and is currently the secondary isotope. Plutonium-239 is also one of the three main isotopes demonstrated usable as fuel in...



Explosive materials may be categorized by the speed at which they expand. Materials that detonate (explode faster than the speed of sound
Speed of sound
The speed of sound is the distance travelled during a unit of time by a sound wave propagating through an elastic medium. In dry air at , the speed of sound is . This is , or about one kilometer in three seconds or approximately one mile in five seconds....

) are said to be high explosives and materials that deflagrate are said to be low explosives. Explosives may also be categorized by their sensitivity
Sensitivity (explosives)
Sensitivity of explosives is the degree to which an explosive can be initiated by impact, heat, or friction.Sensitivity, along with stability and brisance are three of the most significant properties of explosives that affect their use and application. All explosive compounds have a certain amount...

. Sensitive materials that can be initiated by a relatively small amount of heat or pressure are primary explosives and materials that are relatively insensitive are secondary explosives.

History



Though early thermal weapons, such as Greek fire
Greek fire
Greek fire was an incendiary weapon used by the Byzantine Empire. The Byzantines typically used it in naval battles to great effect as it could continue burning while floating on water....

, have existed since ancient times, the first widely used explosive in warfare and mining was black powder, invented in 9th century China ( see the history of gunpowder
History of gunpowder
Gunpowder was the first chemical explosive and the only one known until the invention of nitrocellulose, nitroglycerin, smokeless powder and TNT in the second half of the 19th century...

 ). This material was sensitive to water, and evolved lots of dark smoke. During the 19th century black powder was replaced by nitroglycerine, nitrocellulose
Nitrocellulose
Nitrocellulose is a highly flammable compound formed by nitrating cellulose through exposure to nitric acid or another powerful nitrating agent. When used as a propellant or low-order explosive, it is also known as guncotton...

, smokeless powder
Smokeless powder
Smokeless powder is the name given to a number of propellants used in firearms and artillery which produce negligible smoke when fired, unlike the older gunpowder which they replaced...

, dynamite
Dynamite
Dynamite is an explosive material based on nitroglycerin, initially using diatomaceous earth , or another absorbent substance such as powdered shells, clay, sawdust, or wood pulp. Dynamites using organic materials such as sawdust are less stable and such use has been generally discontinued...

 and gelignite
Gelignite
Gelignite, also known as blasting gelatin or simply jelly, is an explosive material consisting of collodion-cotton dissolved in either nitroglycerine or nitroglycol and mixed with wood pulp and saltpetre .It was invented in 1875 by Alfred Nobel, who had earlier invented dynamite...

 (the two latter invented by Alfred Nobel
Alfred Nobel
Alfred Bernhard Nobel was a Swedish chemist, engineer, innovator, and armaments manufacturer. He is the inventor of dynamite. Nobel also owned Bofors, which he had redirected from its previous role as primarily an iron and steel producer to a major manufacturer of cannon and other armaments...

). World War II saw an extensive use of new explosives ( see explosives used during World War II ). In turn, these have largely been replaced by modern explosives such as trinitrotoluene and C-4
C-4 (explosive)
C4 or Composition C4 is a common variety of the plastic explosive known as Composition C.-Composition and manufacture:C4 is made up of explosives, plastic binder, plasticizer and usually marker or odorizing taggant chemicals such as 2,3-dimethyl-2,3-dinitrobutane to help detect the explosive and...

.

The increased availability of chemicals has allowed the construction of improvised explosive device
Improvised explosive device
An improvised explosive device , also known as a roadside bomb, is a homemade bomb constructed and deployed in ways other than in conventional military action...

s.

Chemical



An explosion is a type of spontaneous chemical reaction (once initiated) that is driven by both a large exothermic change (great release of heat) and a large positive entropy change (great quantities of gases are released) in going from reactants to products, thereby constituting a very thermodynamically favorable process in addition to one that propagates very rapidly. Thus, explosives are substances that contain a large amount of energy stored in chemical bonds. The energetic stability of the gaseous products and, hence, their generation comes from the formation of strongly bonded species like carbon monoxide, carbon dioxide, and (di)nitrogen, which contain strong double and triple bonds having bond strengths of nearly 1,000 kJ/mole. Consequently, most commercial explosives are organic compounds containing -NO2
Nitro
-Chemistry:*Nitroglycerin, an explosive chemical compound*Nitromethane, the simplest organic nitro compound; also used to fuel high-performance internal-combustion engines*Nitrous oxide, "laughing gas", used in some dental procedures as an anaesthetic...

, -ONO2
Nitrate
The nitrate ion is a polyatomic ion with the molecular formula NO and a molecular mass of 62.0049 g/mol. It is the conjugate base of nitric acid, consisting of one central nitrogen atom surrounded by three identically-bonded oxygen atoms in a trigonal planar arrangement. The nitrate ion carries a...

 and -NHNO2
Nitroamine
Nitroamines are organic compounds that contain the nitroamino functional group, R2N-NO2. The R's are the continuation of the ring structure, see RDX. Examples of nitroamines are the explosives HMX, cyclotrimethylene trinitramine, Hexanitrohexaazaisowurtzitane and tetryl...

 groups that when detonated release gases like the aforementioned ones (e.g., nitroglycerin, TNT
TNT
TNT is the chemical explosive trinitrotoluene.TNT or T.N.T. may also refer to:-Television:* TNT , American cable television channel and its international offshoots* TNT , a television station in Launceston, Australia...

, HMX
HMX
HMX, also called octogen, is a powerful and relatively insensitive nitroamine high explosive, chemically related to RDX. Like RDX, the name has been variously listed as High Melting eXplosive, Her Majesty's eXplosive, High-velocity Military eXplosive, or High-Molecular-weight rdX.The molecular...

, PETN
PETN
Pentaerythritol tetranitrate , also known as PENT, PENTA, TEN, corpent, penthrite , is the nitrate ester of pentaerythritol. Penta refers to the five carbon atoms of the neopentane skeleton.PETN is most well known as an explosive...

, nitrocellulose
Nitrocellulose
Nitrocellulose is a highly flammable compound formed by nitrating cellulose through exposure to nitric acid or another powerful nitrating agent. When used as a propellant or low-order explosive, it is also known as guncotton...

).

Explosives are classified as low or high explosives according to their rates of burn
Burn
A burn is an injury to flesh caused by heat, electricity, chemicals, light, radiation, or friction.Burn may also refer to:*Combustion*Burn , type of watercourses so named in Scotland and north-eastern England...

: low explosives burn rapidly (or deflagrate), while high explosives detonate. While these definitions are distinct, the problem of precisely measuring rapid decomposition makes practical classification of explosives difficult.

Decomposition


The chemical decomposition
Chemical decomposition
Chemical decomposition, analysis or breakdown is the separation of a chemical compound into elements or simpler compounds. It is sometimes defined as the exact opposite of a chemical synthesis. Chemical decomposition is often an undesired chemical reaction...

 of an explosive may take years, days, hours, or a fraction of a second. The slower processes of decomposition take place in storage and are of interest only from a stability standpoint. Of more interest are the two rapid forms of decomposition, deflagration
Deflagration
Deflagration is a term describing subsonic combustion that usually propagates through thermal conductivity; hot burning material heats the next layer of cold material and ignites it. Most "fire" found in daily life, from flames to explosions, is deflagration...

 and detonation
Detonation
Detonation involves a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations are observed in both conventional solid and liquid explosives, as well as in reactive gases...

.

Deflagration



In deflagration, the decomposition of the explosive material is propagated by a flame front, which moves slowly through the explosive material in contrast to detonation
Detonation
Detonation involves a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations are observed in both conventional solid and liquid explosives, as well as in reactive gases...

. Deflagration is a characteristic of low explosive material.

Detonation



This term is used to describe an explosive phenomenon whereby the decomposition is propagated
Wave propagation
Wave propagation is any of the ways in which waves travel.With respect to the direction of the oscillation relative to the propagation direction, we can distinguish between longitudinal wave and transverse waves....

 by the explosive shock wave
Shock wave
A shock wave is a type of propagating disturbance. Like an ordinary wave, it carries energy and can propagate through a medium or in some cases in the absence of a material medium, through a field such as the electromagnetic field...

 traversing the explosive material. The shock front is capable of passing through the high explosive material at great speeds, typically thousands of metres per second.

Exotic


In addition to chemical explosives, there exist varieties of more exotic explosive material, and theoretical methods of causing explosions. Examples include nuclear explosive
Nuclear explosive
A nuclear explosive is an explosive device that derives its energy from nuclear reactions. Almost all nuclear explosive devices that have been designed and produced are nuclear weapons intended for warfare....

s, antimatter
Antimatter
In particle physics, antimatter is the extension of the concept of the antiparticle to matter, where antimatter is composed of antiparticles in the same way that normal matter is composed of particles...

, and abruptly heating a substance to a plasma
Plasma (physics)
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...

 state with a high-intensity laser
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...

 or electric arc
Electric arc
An electric arc is an electrical breakdown of a gas which produces an ongoing plasma discharge, resulting from a current flowing through normally nonconductive media such as air. A synonym is arc discharge. An arc discharge is characterized by a lower voltage than a glow discharge, and relies on...

.

Laser and arc heating are used in practice in laser detonators, exploding-bridgewire detonator
Exploding-bridgewire detonator
The exploding-bridgewire detonator is a type of detonator used to initiate the detonation reaction in explosive materials, similar to a blasting cap in that it is fired using an electric current...

s, and exploding foil initiator
Slapper detonator
A slapper detonator, also called exploding foil initiator , is a relatively recent kind of a detonator developed in Lawrence Livermore National Laboratory...

s, where a shock wave and then detonation in conventional chemical explosive material is created by laser or electric arc heating. Laser and electric energy are not currently practically used directly for the majority of the energy, only to initiate reactions.

Properties of explosive materials


To determine the suitability of an explosive substance for a particular use, its physical
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...

 properties must first be known. The usefulness of an explosive can only be appreciated when the properties and the factors affecting them are fully understood. Some of the more important characteristics are listed below:

Availability and cost


The availability and cost of explosives is determined by the availability of the raw materials and the cost, complexity, and safety of the manufacturing operations.

Sensitivity



Regarding an explosive, this refers to the ease with which it can be ignited or detonated—i.e., the amount and intensity of shock
Electric shock
Electric Shock of a body with any source of electricity that causes a sufficient current through the skin, muscles or hair. Typically, the expression is used to denote an unwanted exposure to electricity, hence the effects are considered undesirable....

, friction
Friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and/or material elements sliding against each other. There are several types of friction:...

, or heat
Heat
In physics and thermodynamics, heat is energy transferred from one body, region, or thermodynamic system to another due to thermal contact or thermal radiation when the systems are at different temperatures. It is often described as one of the fundamental processes of energy transfer between...

 that is required. When the term sensitivity is used, care must be taken to clarify what kind of sensitivity is under discussion. The relative sensitivity of a given explosive to impact may vary greatly from its sensitivity to friction or heat. Some of the test methods used to determine sensitivity are as follows:
  • Impact Sensitivity is expressed in terms of the distance through which a standard weight must be dropped to cause the material to explode.
  • Friction
    Friction
    Friction is the force resisting the relative motion of solid surfaces, fluid layers, and/or material elements sliding against each other. There are several types of friction:...

    Sensitivity is expressed in terms of what occurs when a weighted pendulum scrapes across the material (snaps, crackles, ignites, and/or explodes).
  • Heat
    Heat
    In physics and thermodynamics, heat is energy transferred from one body, region, or thermodynamic system to another due to thermal contact or thermal radiation when the systems are at different temperatures. It is often described as one of the fundamental processes of energy transfer between...

    Sensitivity is expressed in terms of the temperature at which flashing or explosion of the material occurs.


Sensitivity is an important consideration in selecting an explosive for a particular purpose. The explosive in an armor-piercing projectile must be relatively insensitive, or the shock of impact would cause it to detonate before it penetrated to the point desired. The explosive lenses around nuclear charges are also designed to be highly insensitive, to minimize the risk of accidental detonation.

Sensitivity to initiation


The index of the capacity of the explosive to be initiated into detonation in a sustained manner. It is defined by the power of the detonator which is certain to prime the explosive to a sustained and continuous detonation. Reference is made to the Sellier-Bellot scale that consists of a series of 10 detonators, from n. 1 to n. 10, each of which corresponds to an increasing charge weight. In practice most of the explosives on the market today are sensitive to the n. 8 detonator, where the charge corresponds to 2 grams of mercury fulminate.

Velocity of detonation


The velocity with which the reaction process propagates in the mass of the explosive. Most commercial mining explosives have detonation velocities ranging from 1800 m/s to 8000 m/s. Today, velocity of detonation can be measured with accuracy. Together with density it is an important element influencing the yield of the energy transmitted (for both, atmospheric overpressure and ground acceleration).

Stability



Stability is the ability of an explosive to be stored without deterioration
Chemical decomposition
Chemical decomposition, analysis or breakdown is the separation of a chemical compound into elements or simpler compounds. It is sometimes defined as the exact opposite of a chemical synthesis. Chemical decomposition is often an undesired chemical reaction...

.

The following factors affect the stability of an explosive:
  • Chemical constitution. In the strictest technical sense, the word "stability" is a thermodynamic term referring to the energy of a substance relative to a reference state or to some other substance. However, in the context of explosives, stability is commonly used to refer to the ease of detonation, which is concerned with kinetics
    Chemical kinetics
    Chemical kinetics, also known as reaction kinetics, is the study of rates of chemical processes. Chemical kinetics includes investigations of how different experimental conditions can influence the speed of a chemical reaction and yield information about the reaction's mechanism and transition...

     (i.e. the rate of decomposition). It is perhaps best, then, to differentiate between the terms thermodynamically stable and kinetically stable by referring to the latter as "inert." Contrarily, a kinetically unstable substance is said to be "labile." It is generally recognized that certain groups like nitro
    Nitro
    -Chemistry:*Nitroglycerin, an explosive chemical compound*Nitromethane, the simplest organic nitro compound; also used to fuel high-performance internal-combustion engines*Nitrous oxide, "laughing gas", used in some dental procedures as an anaesthetic...

     (–NO2), nitrate
    Nitrate
    The nitrate ion is a polyatomic ion with the molecular formula NO and a molecular mass of 62.0049 g/mol. It is the conjugate base of nitric acid, consisting of one central nitrogen atom surrounded by three identically-bonded oxygen atoms in a trigonal planar arrangement. The nitrate ion carries a...

     (–ONO2), and azide
    Azide
    Azide is the anion with the formula N3−. It is the conjugate base of hydrazoic acid. N3− is a linear anion that is isoelectronic with CO2 and N2O. Per valence bond theory, azide can be described by several resonance structures, an important one being N−=N+=N−...

     (–N3), are intrinsically labile with respect to decomposition. Kinetically, there exits a low activation barrier to the decomposition reaction. Consequently, these compounds exhibit a high sensitivity to flame or mechanical shock. The chemical bonding in these compounds is characterized by being predominantly covalent in nature and thus they are not thermodynamically stabilized by a high ionic-lattice energy. Furthermore, they generally have positive enthalpies of formation and there is little mechanistic hindrance to internal molecular rearrangement to the more thermodynamically stable (more strongly bonded) decomposition products. For example, in lead azide, Pb(N3)2, the nitrogen atoms are already bonded to one another so there is relatively easy decomposition into Pb and N2.[1]
  • Temperature
    Temperature
    Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...

     of storage.
    The rate of decomposition of explosives increases at higher temperatures. All of the standard military explosives may be considered to have a high degree of stability at temperatures of -10 to +35 °C, but each has a high temperature at which the rate of decomposition
    Thermal decomposition
    Thermal decomposition, or thermolysis, is a chemical decomposition caused by heat. The decomposition temperature of a substance is the temperature at which the substance chemically decomposes....

     rapidly accelerates and stability is reduced. As a rule of thumb, most explosives become dangerously unstable at temperatures exceeding 70 °C.
  • Exposure to the sun
    Sun
    The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

    .
    If exposed to the ultraviolet
    Ultraviolet
    Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...

     rays of the sun, many explosive compounds that contain nitrogen
    Nitrogen
    Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

     groups will rapidly decompose, affecting their stability.
  • Electrical discharge. Electrostatic
    Electrostatic discharge
    Electrostatic discharge is a serious issue in solid state electronics, such as integrated circuits. Integrated circuits are made from semiconductor materials such as silicon and insulating materials such as silicon dioxide...

     or spark
    Electric spark
    An electric spark is a type of electrostatic discharge that occurs when an electric field creates an ionized electrically conductive channel in air producing a brief emission of light and sound. A spark is formed when the electric field strength exceeds the dielectric field strength of air...

     sensitivity to initiation is common to a number of explosives. Static or other electrical discharge may be sufficient to inspire detonation under some circumstances. As a result, the safe handling of explosives and pyrotechnics
    Pyrotechnics
    Pyrotechnics is the science of using materials capable of undergoing self-contained and self-sustained exothermic chemical reactions for the production of heat, light, gas, smoke and/or sound...

     almost always requires electrical grounding
    Ground (electricity)
    In electrical engineering, ground or earth may be the reference point in an electrical circuit from which other voltages are measured, or a common return path for electric current, or a direct physical connection to the Earth....

     of the operator.

Power, performance, and strength


The term power or performance as applied to an explosive refers to its ability to do work. In practice it is defined as the explosive's ability to accomplish what is intended in the way of energy delivery (i.e., fragment projection, air blast, high-velocity jets, underwater shock and bubble energy, etc.). Explosive power or performance is evaluated by a tailored series of tests to assess the material for its intended use. Of the tests listed below, cylinder expansion and air-blast tests are common to most testing programs, and the others support specific applications.
  • Cylinder expansion test. A standard amount of explosive is loaded into a long hollow cylinder
    Cylinder (geometry)
    A cylinder is one of the most basic curvilinear geometric shapes, the surface formed by the points at a fixed distance from a given line segment, the axis of the cylinder. The solid enclosed by this surface and by two planes perpendicular to the axis is also called a cylinder...

    , usually of copper, and detonated at one end. Data is collected concerning the rate of radial expansion of the cylinder and maximum cylinder wall velocity. This also establishes the Gurney energy
    Gurney equations
    The Gurney equations are a set of mathematical formulas used in Explosives engineering to relate how fast an explosive will accelerate a surrounding layer of metal or other material when the explosive detonates...

     or 2E.
  • Cylinder fragmentation. A standard steel cylinder is loaded with explosive and detonated in a sawdust pit. The fragments
    Fragmentation (weaponry)
    Fragmentation is the process by which the casing of an artillery shell, bomb, grenade, etc. is shattered by the detonating high explosive filling. The correct technical terminology for these casing pieces is fragments , although shards or splinters can be used for non-preformed fragments...

     are collected and the size distribution analyzed.
  • Detonation pressure (Chapman-Jouguet condition
    Chapman-Jouguet condition
    The Chapman–Jouguet condition holds approximately in detonation waves in high explosives. It states that the detonation propagates at a velocity at which the reacting gases just reach sonic velocity as the reaction ceases....

    ).
    Detonation
    Detonation
    Detonation involves a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations are observed in both conventional solid and liquid explosives, as well as in reactive gases...

     pressure data derived from measurements of shock waves transmitted into water by the detonation of cylindrical explosive charges of a standard size.
  • Determination of critical diameter. This test establishes the minimum physical size a charge of a specific explosive must be to sustain its own detonation wave. The procedure involves the detonation of a series of charges of different diameters until difficulty in detonation wave propagation is observed.
  • Infinite-diameter detonation velocity. Detonation velocity is dependent on loading density (c), charge diameter, and grain size. The hydrodynamic theory of detonation used in predicting explosive phenomena does not include diameter of the charge, and therefore a detonation velocity, for an imaginary charge of Infinite
    Infinity
    Infinity is a concept in many fields, most predominantly mathematics and physics, that refers to a quantity without bound or end. People have developed various ideas throughout history about the nature of infinity...

     diameter. This procedure requires a series of charges of the same density and physical structure, but different diameters, to be fired and the resulting detonation velocities extrapolated to predict the detonation velocity of a charge of infinite diameter.
  • Pressure versus scaled distance. A charge of specific size is detonated and its pressure effects measured at a standard distance. The values obtained are compared with that for TNT.
  • Impulse versus scaled distance. A charge of specific size is detonated and its impulse (the area under the pressure-time curve) measured versus distance. The results are tabulated and expressed in TNT equivalent.
  • Relative bubble energy (RBE). A 5- to 50 kg charge is detonated in water and piezoelectric gauges measure peak pressure, time constant, impulse, and energy.
The RBE may be defined as Kx 3
RBE = Ks
where K = bubble expansion period for experimental (x) or standard (s) charge.

Brisance



In addition to strength, explosives display a second characteristic, which is their shattering effect or brisance (from the French meaning to "break"), which is distinguished and separate from their total work capacity. This characteristic is of practical importance in determining the effectiveness of an explosion in fragmenting shells, bomb casings, grenade
Grenade
A grenade is a small explosive device that is projected a safe distance away by its user. Soldiers called grenadiers specialize in the use of grenades. The term hand grenade refers any grenade designed to be hand thrown. Grenade Launchers are firearms designed to fire explosive projectile grenades...

s, and the like. The rapidity with which an explosive reaches its peak pressure (power
Power (physics)
In physics, power is the rate at which energy is transferred, used, or transformed. For example, the rate at which a light bulb transforms electrical energy into heat and light is measured in watts—the more wattage, the more power, or equivalently the more electrical energy is used per unit...

) is a measure of its brisance. Brisance values are primarily employed in France and Russia.

The sand crush test is commonly employed to determine the relative brisance in comparison to TNT. No test is capable of directly comparing the explosive properties of two or more compounds; it is important to examine the data from several such tests (sand crush, trauzl
Trauzl lead block test
The Trauzl lead block test, also called the Trauzl test or just Trauzl, is a test used to measure the strength of explosive materials. It was developed by Isidor Trauzl in 1885....

, and so forth) in order to gauge relative brisance. True values for comparison require field experiments.

Density


Density
Density
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...

 of loading refers to the mass of an explosive per unit volume. Several methods of loading are available, including pellet loading, cast loading, and press loading; the one used is determined by the characteristics of the explosive. Dependent upon the method employed, an average density of the loaded charge can be obtained that is within 80–99% of the theoretical maximum density of the explosive. High load density can reduce sensitivity
Sensitivity (explosives)
Sensitivity of explosives is the degree to which an explosive can be initiated by impact, heat, or friction.Sensitivity, along with stability and brisance are three of the most significant properties of explosives that affect their use and application. All explosive compounds have a certain amount...

 by making the mass
Mass
Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...

 more resistant to internal friction
Friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and/or material elements sliding against each other. There are several types of friction:...

. However, if density is increased to the extent that individual crystal
Crystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...

s are crushed, the explosive may become more sensitive. Increased load density also permits the use of more explosive, thereby increasing the power of the warhead
Warhead
The term warhead refers to the explosive material and detonator that is delivered by a missile, rocket, or torpedo.- Etymology :During the early development of naval torpedoes, they could be equipped with an inert payload that was intended for use during training, test firing and exercises. This...

. It is possible to compress an explosive beyond a point of sensitivity, known also as dead-pressing, in which the material is no longer capable of being reliably initiated, if at all.

Volatility


Volatility
Volatility (chemistry)
In chemistry and physics, volatility is the tendency of a substance to vaporize. Volatility is directly related to a substance's vapor pressure. At a given temperature, a substance with higher vapor pressure vaporizes more readily than a substance with a lower vapor pressure.The term is primarily...

 is the readiness with which a substance vaporizes
Vaporization
Vaporization of an element or compound is a phase transition from the liquid or solid phase to gas phase. There are three types of vaporization: evaporation, boiling and sublimation....

. Excessive volatility often results in the development of pressure within rounds of ammunition and separation of mixtures into their constituents. Volatility affects the chemical composition of the explosive such that a marked reduction in stability may occur, which results in an increase in the danger of handling.

Hygroscopicity and water resistance


The introduction of water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

 into an explosive is highly undesirable since it reduces the sensitivity, strength, and velocity of detonation of the explosive. Hygroscopicity is used as a measure of a material's moisture-absorbing tendencies. Moisture affects explosives adversely by acting as an inert material that absorbs heat when vaporized, and by acting as a solvent medium that can cause undesired chemical reactions. Sensitivity, strength, and velocity of detonation are reduced by inert materials that reduce the continuity of the explosive mass. When the moisture content evaporates during detonation, cooling occurs, which reduces the temperature of reaction. Stability is also affected by the presence of moisture since moisture promotes decomposition of the explosive and, in addition, causes corrosion of the explosive's metal container.

Explosives considerably differ from one another as to their behavior in the presence of water. Gelatin dynamites containing nitroglycerine have a degree of water resistance. Explosives based on ammonium nitrate have little or no water resistance, due to the reaction between ammonium nitrate and water: liberating ammonia, nitrogen dioxide and hydrogen peroxide. Plus, ammonium nitrate is hygroscopic, susceptible to damp, hence the above.

Toxicity


Due to their chemical structure, most explosives are toxic
Toxicity
Toxicity is the degree to which a substance can damage a living or non-living organisms. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell or an organ , such as the liver...

 to some extent. Explosive product gases can also be toxic.

Explosive train



Another property of explosive material is where it exists in the explosive train of the device or system. An example of this is a pyrotechnic lead igniting a booster, which causes the main charge to detonate.

Volume of products of explosion


Avogadro's law
Avogadro's law
Avogadro's law is a gas law named after Amedeo Avogadro who, in 1811, hypothesized that two given samples of an ideal gas, at the same temperature, pressure and volume, contain the same number of molecules...

 states that equal volumes of all gases under the same conditions of temperature and pressure contain the same number of molecules, that is, the molar volume
Molar volume
The molar volume, symbol Vm, is the volume occupied by one mole of a substance at a given temperature and pressure. It is equal to the molar mass divided by the mass density...

 of one gas is equal to the molar volume of any other gas. The molar volume of any gas at 0°C and under normal atmospheric pressure is very nearly 22.4 liters. Thus, considering the nitroglycerin reaction,
C3H5(NO3)3 → 3CO2 + 2.5H2O + 1.5N2 + 0.25O2


the explosion of one mole of nitroglycerin produces 3 moles of CO2, 2.5 moles of H2O, 1.5 moles of N2, and 0.25 mole of O2, all in the gaseous state. Since a molar volume is the volume of one mole of gas, one mole of nitroglycerin produces 3 + 2.5 + 1.5 + 0.25 = 7.25 molar volumes of gas; and these molar volumes at 0°C and atmospheric pressure form an actual volume of 7.25 × 22.4 = 162.4 liters of gas.

Based upon this simple beginning, it can be seen that the volume of the products of explosion can be predicted for any quantity of the explosive. Further, by employing Charles' Law for perfect gases, the volume of the products of explosion may also be calculated for any given temperature. This law states that at a constant pressure a perfect gas expands 1/273.15 of its volume at 0 °C, for each degree Celsius of rise in temperature.

Therefore, at 15 °C (288.15 kelvin
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...

) the molar volume of an ideal gas is
V15 = 22.414 (288.15/273.15) = 23.64 liters per mole


Thus, at 15 °C the volume of gas produced by the explosive decomposition of one mole of nitroglycerin becomes
V = (23.64 l/mol)(7.25 mol) = 171.4 l

Oxygen balance (OB% or Ω)



Oxygen balance
Oxygen balance
Oxygen balance is an expression that is used to indicate the degree to which an explosive can be oxidized. If an explosive molecule contains just enough oxygen to form carbon dioxide from carbon, water from hydrogen molecules, all of its sulfur dioxide from sulfur, and all metal oxides from metals...

 is an expression that is used to indicate the degree to which an explosive can be oxidized. If an explosive molecule contains just enough oxygen to convert all of its carbon to carbon dioxide, all of its hydrogen to water, and all of its metal to metal oxide with no excess, the molecule is said to have a zero oxygen balance. The molecule is said to have a positive oxygen balance if it contains more oxygen than is needed and a negative oxygen balance if it contains less oxygen than is needed. The sensitivity, strength
Strength (explosive)
In explosive materials, strength is the parameter determining the ability of the explosive to move the surrounding material. It is related to the total gas yield of the reaction, and the amount of heat produced...

, and brisance
Brisance
Brisance is the shattering capability of an explosive. It is a measure of the rapidity with which an explosive develops its maximum pressure. The term originates from the French verb "briser", which means to break or shatter...

 of an explosive are all somewhat dependent upon oxygen balance and tend to approach their maximums as oxygen balance approaches zero.

Chemical composition


A chemical explosive may consist of either a chemically pure compound, such as nitroglycerin, or a mixture of a fuel
Fuel
Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...

 and an oxidizer, such as black powder or grain dust and air.

Chemically pure compounds


Some chemical compounds are unstable in that, when shocked, they react, possibly to the point of detonation. Each molecule of the compound dissociates into two or more new molecules (generally gases) with the release of energy.
  • Nitroglycerin: A highly unstable and sensitive liquid.
  • Acetone peroxide
    Acetone peroxide
    Acetone peroxide is an organic peroxide and a primary high explosive. It takes the form of a white crystalline powder with a distinctive bleach-like odor....

    : A very unstable white organic peroxide
    Organic peroxide
    Organic peroxides are organic compounds containing the peroxide functional group . If the R' is hydrogen, the compound is called an organic hydroperoxide. Peresters have general structure RCOOR. The O-O bond easily breaks and forms free radicals of the form RO·...

    .
  • TNT: Yellow insensitive crystals that can be melted and cast without detonation.
  • Nitrocellulose
    Nitrocellulose
    Nitrocellulose is a highly flammable compound formed by nitrating cellulose through exposure to nitric acid or another powerful nitrating agent. When used as a propellant or low-order explosive, it is also known as guncotton...

    : A nitrated polymer which can be a high or low explosive depending on nitration level and conditions.
  • RDX
    RDX
    RDX, an initialism for Research Department Explosive, is an explosive nitroamine widely used in military and industrial applications. It was developed as an explosive which was more powerful than TNT, and it saw wide use in WWII. RDX is also known as cyclonite, hexogen , and T4...

    , PETN
    PETN
    Pentaerythritol tetranitrate , also known as PENT, PENTA, TEN, corpent, penthrite , is the nitrate ester of pentaerythritol. Penta refers to the five carbon atoms of the neopentane skeleton.PETN is most well known as an explosive...

    , HMX
    HMX
    HMX, also called octogen, is a powerful and relatively insensitive nitroamine high explosive, chemically related to RDX. Like RDX, the name has been variously listed as High Melting eXplosive, Her Majesty's eXplosive, High-velocity Military eXplosive, or High-Molecular-weight rdX.The molecular...

    : Very powerful explosives which can be used pure or in plastic explosives.
    • C-4 (or Composition C-4): An RDX
      RDX
      RDX, an initialism for Research Department Explosive, is an explosive nitroamine widely used in military and industrial applications. It was developed as an explosive which was more powerful than TNT, and it saw wide use in WWII. RDX is also known as cyclonite, hexogen , and T4...

       plastic explosive
      Plastic explosive
      Plastic explosive is a specialised form of explosive material. It is a soft and hand moldable solid material. Plastic explosives are properly known as putty explosives within the field of explosives engineering....

       plasticized to be adhesive and malleable.


The above compositions may describe the majority of the explosive material, but a practical explosive will often include small percentages of other materials. For example, dynamite
Dynamite
Dynamite is an explosive material based on nitroglycerin, initially using diatomaceous earth , or another absorbent substance such as powdered shells, clay, sawdust, or wood pulp. Dynamites using organic materials such as sawdust are less stable and such use has been generally discontinued...

 is a mixture of highly sensitive nitroglycerin with sawdust
Sawdust
Sawdust is a by-product of cutting lumber with a saw, composed of fine particles of wood. It can present a hazard in manufacturing industries, especially in terms of its flammability....

, powdered silica, or most commonly diatomaceous earth
Diatomaceous earth
Diatomaceous earth also known as diatomite or kieselgur/kieselguhr, is a naturally occurring, soft, siliceous sedimentary rock that is easily crumbled into a fine white to off-white powder. It has a particle size ranging from less than 1 micrometre to more than 1 millimetre, but typically 10 to...

, which act as stabilizers. Plastics and polymers may be added to bind powders of explosive compounds; waxes may be incorporated to make them safer to handle; aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 powder may be introduced to increase total energy and blast effects. Explosive compounds are also often "alloyed": HMX or RDX powders may be mixed (typically by melt-casting) with TNT to form Octol
Octol
Octol is a melt-castable, high explosive mixture consisting of HMX and TNT in different weight proportions.-Composition:Two formulations are commonly used:* 70% HMX & 30% TNT* 75% HMX & 25% TNT...

 or Cyclotol
Cyclotol
Cyclotol is an explosive consisting of castable mixtures of RDX and TNT.It is related to the more common Composition B, which is roughly 60% RDX and 40% TNT; various compositions of Cyclotol contain from 65% to 80% RDX....

.

Mixture of oxidizer and fuel


An oxidizer is a pure substance (molecule
Molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...

) that in a chemical reaction can contribute some atoms of one or more oxidizing elements, in which the fuel
Fuel
Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...

 component of the explosive burns. On the simplest level, the oxidizer may itself be an oxidizing element
Chemical element
A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. Familiar examples of elements include carbon, oxygen, aluminum, iron, copper, gold, mercury, and lead.As of November 2011, 118 elements...

, such as gaseous or liquid
Liquid
Liquid is one of the three classical states of matter . Like a gas, a liquid is able to flow and take the shape of a container. Some liquids resist compression, while others can be compressed. Unlike a gas, a liquid does not disperse to fill every space of a container, and maintains a fairly...

 oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

.
  • Black powder: Potassium nitrate
    Potassium nitrate
    Potassium nitrate is a chemical compound with the formula KNO3. It is an ionic salt of potassium ions K+ and nitrate ions NO3−.It occurs as a mineral niter and is a natural solid source of nitrogen. Its common names include saltpetre , from medieval Latin sal petræ: "stone salt" or possibly "Salt...

    , charcoal
    Charcoal
    Charcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen...

     and sulfur
    Sulfur
    Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

  • Flash powder
    Flash powder
    Flash powder is a pyrotechnic composition, a mixture of oxidizer and metallic fuel, which burns quickly and if confined produces a loud report. It is widely used in theatrical pyrotechnics and fireworks and was once used for flashes in photography.Different varieties of flash powder are made from...

    : Fine metal powder (usually aluminum or magnesium
    Magnesium
    Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...

    ) and a strong oxidizer (e.g. potassium chlorate
    Potassium chlorate
    Potassium chlorate is a compound containing potassium, chlorine and oxygen atoms, with the molecular formula KClO3. In its pure form, it is a white crystalline substance. It is the most common chlorate in industrial use...

     or perchlorate
    Potassium perchlorate
    Potassium perchlorate is the inorganic salt with the chemical formula KClO4. Like other perchlorates, this salt is a strong oxidizer and potentially reacts with many organic substances...

    ).
  • Ammonal
    Ammonal
    Ammonal is an explosive made up of ammonium nitrate, trinitrotoluene , and aluminium powder.The ammonium nitrate functions as an oxidizer and aluminium as a power enhancer. To some extent the aluminium makes it more sensitive to detonation...

    : Ammonium nitrate and aluminum powder.
  • Armstrong's mixture
    Armstrong's mixture
    Armstrong's mixture is a highly sensitive primary explosive. Its primary ingredients are red phosphorus and strong oxidizer, such as potassium chlorate and potassium perchlorate. Sulfur and calcium carbonate might be present in small amounts, though other additives are also used. Commercially,...

    : Potassium chlorate
    Potassium chlorate
    Potassium chlorate is a compound containing potassium, chlorine and oxygen atoms, with the molecular formula KClO3. In its pure form, it is a white crystalline substance. It is the most common chlorate in industrial use...

     and red phosphorus. This is a very sensitive mixture. It is a primary high explosive in which sulfur is substituted for some or all phosphorus to slightly decrease sensitivity.
  • Sprengel explosive
    Sprengel explosive
    Sprengel explosives are a generic class of materials invented by Hermann Sprengel in the 1870s. They consist of stoichiometric mixtures of strong oxidisers and reactive fuels, mixed just prior to use in order to enhance safety...

    s
    : A very general class incorporating any strong oxidizer and highly reactive fuel, although in practice the name most commonly was applied to mixtures of chlorate
    Chlorate
    The chlorate anion has the formula ClO. In this case, the chlorine atom is in the +5 oxidation state. "Chlorate" can also refer to chemical compounds containing this anion; chlorates are the salts of chloric acid. "Chlorate", when followed by a roman numeral in parentheses, e.g...

    s and nitroaromatics.
    • ANFO
      ANFO
      ANFO is a widely used bulk industrial explosive mixture. It consists of 94 percent porous prilled ammonium nitrate , that acts as the oxidizing agent and absorbent for the fuel — six percent Number 2 Fuel Oil...

      : Ammonium nitrate and fuel oil
      Fuel oil
      Fuel oil is a fraction obtained from petroleum distillation, either as a distillate or a residue. Broadly speaking, fuel oil is any liquid petroleum product that is burned in a furnace or boiler for the generation of heat or used in an engine for the generation of power, except oils having a flash...

      .
    • Cheddite
      Cheddite
      Cheddite is a class of explosive materials that were originally manufactured in the town of Chedde in Haute-Savoie, France in the early twentieth century. Closely related to Sprengel explosives, cheddites consisted of a high proportion of inorganic chlorates mixed with nitroaromatics Cheddite is a...

      s
      : Chlorate
      Chlorate
      The chlorate anion has the formula ClO. In this case, the chlorine atom is in the +5 oxidation state. "Chlorate" can also refer to chemical compounds containing this anion; chlorates are the salts of chloric acid. "Chlorate", when followed by a roman numeral in parentheses, e.g...

      s or perchlorate
      Perchlorate
      Perchlorates are the salts derived from perchloric acid . They occur both naturally and through manufacturing. They have been used as a medicine for more than 50 years to treat thyroid gland disorders. They are used extensively within the pyrotechnics industry, and ammonium perchlorate is also a...

      s and oil.
    • Oxyliquit
      Oxyliquit
      An oxyliquit, also called liquid air explosive or liquid oxygen explosive, is an explosive material made of a mixture of liquid air or liquid oxygen with a suitable fuel, usually carbon or some organic chemical An oxyliquit, also called liquid air explosive or liquid oxygen explosive, is an...

      s
      : Mixtures of organic materials and liquid oxygen
      Liquid oxygen
      Liquid oxygen — abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries — is one of the physical forms of elemental oxygen.-Physical properties:...

      .
    • Panclastite
      Panclastite
      Panclastites are a class of Sprengel explosives similar to oxyliquits. They were first suggested in 1881 by Eugène Turpin, a French chemist. They are a mixture of liquid dinitrogen tetroxide serving as oxidizer with a suitable fuel, e.g. carbon disulfide, in the 3:2 volume ratio. Other fuel being...

      s
      : Mixtures of organic materials and dinitrogen tetroxide
      Dinitrogen tetroxide
      Dinitrogen tetroxide is the chemical compound N2O4. It is a useful reagent in chemical synthesis. It forms an equilibrium mixture with nitrogen dioxide; some call this mixture dinitrogen tetroxide, while some call it nitrogen dioxide.Dinitrogen tetroxide is a powerful oxidizer, making it highly...

      .

Primary explosive


A primary explosive is an explosive that is extremely sensitive to stimuli such as impact, friction
Friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and/or material elements sliding against each other. There are several types of friction:...

, heat
Heat
In physics and thermodynamics, heat is energy transferred from one body, region, or thermodynamic system to another due to thermal contact or thermal radiation when the systems are at different temperatures. It is often described as one of the fundamental processes of energy transfer between...

, static electricity, or electromagnetic radiation
Electromagnetic radiation
Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...

. A relatively small amount of energy is required for initiation
Initiation
Initiation is a rite of passage ceremony marking entrance or acceptance into a group or society. It could also be a formal admission to adulthood in a community or one of its formal components...

. As a very general rule, primary explosives are considered to be those compounds that are more sensitive than PETN
PETN
Pentaerythritol tetranitrate , also known as PENT, PENTA, TEN, corpent, penthrite , is the nitrate ester of pentaerythritol. Penta refers to the five carbon atoms of the neopentane skeleton.PETN is most well known as an explosive...

. As a practical measure, primary explosives are sufficiently sensitive that they can be reliably initiated with a blow from a hammer; however, PETN can usually be initiated in this manner, so this is only a very broad guideline. Additionally, several compounds, such as nitrogen triiodide
Nitrogen triiodide
Nitrogen triiodide is the inorganic compound with the formula NI3. It is an extremely sensitive contact explosive: small quantities explode with a gunpowder-like snap when touched even lightly, releasing a purple cloud of iodine vapor...

, are so sensitive that they cannot even be handled without detonating.

Primary explosives are often used in detonator
Detonator
A detonator is a device used to trigger an explosive device. Detonators can be chemically, mechanically, or electrically initiated, the latter two being the most common....

s or to trigger larger charges of less sensitive secondary explosives. Primary explosives are commonly used in blasting cap
Blasting cap
A blasting cap is a small sensitive primary explosive device generally used to detonate a larger, more powerful and less sensitive secondary explosive such as TNT, dynamite, or plastic explosive....

s and percussion cap
Percussion cap
The percussion cap, introduced around 1830, was the crucial invention that enabled muzzleloading firearms to fire reliably in any weather.Before this development, firearms used flintlock ignition systems which produced flint-on-steel sparks to ignite a pan of priming powder and thereby fire the...

s to translate a physical shock signal. In other situations, different signals such as electrical/physical shock, or in the case of laser detonation systems, light, are used to initiate an action, i.e., an explosion. A small quantity, usually milligrams, is sufficient to initiate a larger charge of explosive that is usually safer to handle.

Examples of primary high explosives are:
  • Acetone peroxide
    Acetone peroxide
    Acetone peroxide is an organic peroxide and a primary high explosive. It takes the form of a white crystalline powder with a distinctive bleach-like odor....

  • Ammonium permanganate
    Ammonium permanganate
    Ammonium permanganate is the chemical compound NH4MnO4, or NH3·HMnO4. It is soluble in water. It is a strong oxidizer, owing to its permanganate anion, and it is a moderately strong explosive, owing to the combination of oxidizer permanganate anion and reducing ammonium cation...

  • Azo-clathrates
  • Copper acetylide
  • Diazodinitrophenol
  • Hexamethylene triperoxide diamine
    Hexamethylene triperoxide diamine
    Hexamethylene triperoxide diamine is ahigh explosive organic compound, first synthesised in 1885 by Legler. The theorised structure lent itself well to acting as an initiating, or primary explosive...

  • Lead azide
  • Lead styphnate
    Lead styphnate
    Lead styphnate , whose name is derived from styphnic acid, is an explosive used as a component in primer and detonator mixtures for less sensitive secondary explosives....

  • Lead picrate
    Lead picrate
    Lead picrate, Pb2, is an initiating explosive, and thus highly sensitive.For demonstration purposes, it can be most easily and safely prepared in situ. Picric acid is mixed with red lead , and then heated. It is not recommended that more than 50mg is ever made at any one time. At around...

  • Mercury(II) fulminate
    Mercury(II) fulminate
    Mercury fulminate, or Hg2, is a primary explosive. It is highly sensitive to friction and shock. It is mainly used as a trigger for other explosives in percussion caps and blasting caps...

  • Nitrogen trichloride
    Nitrogen trichloride
    Nitrogen trichloride, also known as trichloramine, is the chemical compound with the formula NCl3. This yellow, oily, pungent-smelling liquid is most commonly encountered as a byproduct of chemical reactions between ammonia-derivatives and chlorine .In pure form, NCl3 is highly reactive...

  • Nitrogen triiodide
    Nitrogen triiodide
    Nitrogen triiodide is the inorganic compound with the formula NI3. It is an extremely sensitive contact explosive: small quantities explode with a gunpowder-like snap when touched even lightly, releasing a purple cloud of iodine vapor...

  • Nitroglycerin
  • Silver azide
    Silver azide
    Silver azide is the chemical compound with the formula AgN3. This colorless solid is a well-known explosive.-Structure and chemistry:Silver azide can be prepared by treating an aqueous solution of silver nitrate with sodium azide...

  • Silver acetylide
    Silver acetylide
    Silver acetylide is an inorganic chemical compound with the formula Ag2C2, a metal acetylide. The name is derived from the way it is synthesized, and emphasizes that the compound can be regarded as a salt of the weak acid, acetylene. Since acetylene is called "ethyne" in the modern IUPAC...

  • Silver fulminate
    Silver fulminate
    Silver fulminate is an explosive, ionic, fulminic acid salt of silver.Silver fulminate is a primary explosive that has very little practical value due to its extreme sensitivity to impact, heat, pressure and electricity...

  • Sodium azide
    Sodium azide
    Sodium azide is the inorganic compound with the formula NaN3. This colourless azide salt is the gas-forming component in many car airbag systems. It is used for the preparation of other azide compounds. It is an ionic substance and is highly soluble in water. It is extremely...

  • Tetrazine
    Tetrazine
    Tetrazine is an unstable compound that consists of a six-membered aromatic ring containing four nitrogen atoms with the molecular formula C2H2N4. The name tetrazine is used in the nomenclature of derivatives of this compound...

  • Tetraamine copper complexes
  • Tetrazoles


Secondary explosive


A secondary explosive is less sensitive than a primary explosive and require substantially more energy to be initiated. Because they are less sensitive they are usable in a wider variety of applications and are safer to handle and store. Secondary explosives are used in larger quantities in an explosive train and are usually initiated by a smaller quantity of a primary explosive.

Examples of secondary explosives include TNT and RDX
RDX
RDX, an initialism for Research Department Explosive, is an explosive nitroamine widely used in military and industrial applications. It was developed as an explosive which was more powerful than TNT, and it saw wide use in WWII. RDX is also known as cyclonite, hexogen , and T4...

.

Tertiary explosive


Tertiary explosives, also called blasting agents, are so insensitive to shock that they cannot be reliably detonated by practical quantities of primary explosive, and instead require an intermediate explosive booster
Explosive booster
An explosive booster acts as a bridge between a low energy explosive and a low sensitivity explosive such as TNT. It increases the explosive shockwave from an initiating explosive to the degree sufficient to detonate the secondary charge.Unlike C4 plastic explosive, not all explosives can be...

 of secondary explosive. These are primarily used in large-scale mining
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...

 and construction
Construction
In the fields of architecture and civil engineering, construction is a process that consists of the building or assembling of infrastructure. Far from being a single activity, large scale construction is a feat of human multitasking...

 operations, and in terrorism
Terrorism
Terrorism is the systematic use of terror, especially as a means of coercion. In the international community, however, terrorism has no universally agreed, legally binding, criminal law definition...

.

ANFO
ANFO
ANFO is a widely used bulk industrial explosive mixture. It consists of 94 percent porous prilled ammonium nitrate , that acts as the oxidizing agent and absorbent for the fuel — six percent Number 2 Fuel Oil...

 is an example of a tertiary explosive.

Low explosives


Low explosives are compounds where the rate of decomposition proceeds through the material at less than the speed of sound
Speed of sound
The speed of sound is the distance travelled during a unit of time by a sound wave propagating through an elastic medium. In dry air at , the speed of sound is . This is , or about one kilometer in three seconds or approximately one mile in five seconds....

. The decomposition is propagated by a flame front (deflagration
Deflagration
Deflagration is a term describing subsonic combustion that usually propagates through thermal conductivity; hot burning material heats the next layer of cold material and ignites it. Most "fire" found in daily life, from flames to explosions, is deflagration...

) which travels much more slowly through the explosive material than a shock wave
Shock wave
A shock wave is a type of propagating disturbance. Like an ordinary wave, it carries energy and can propagate through a medium or in some cases in the absence of a material medium, through a field such as the electromagnetic field...

 of a high explosive. Under normal conditions
Standard conditions for temperature and pressure
Standard condition for temperature and pressure are standard sets of conditions for experimental measurements established to allow comparisons to be made between different sets of data...

, low explosives undergo deflagration
Deflagration
Deflagration is a term describing subsonic combustion that usually propagates through thermal conductivity; hot burning material heats the next layer of cold material and ignites it. Most "fire" found in daily life, from flames to explosions, is deflagration...

 at rates that vary from a few centimeters per second to approximately 400 metres per second. It is possible for them to deflagrate very quickly, producing an effect similar to a detonation
Detonation
Detonation involves a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations are observed in both conventional solid and liquid explosives, as well as in reactive gases...

. This can happen under higher pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...

 or temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...

, which usually occurs when ignited in a confined space.

A low explosive is usually a mixture of a combustible substance and an oxidant that decomposes rapidly (deflagration
Deflagration
Deflagration is a term describing subsonic combustion that usually propagates through thermal conductivity; hot burning material heats the next layer of cold material and ignites it. Most "fire" found in daily life, from flames to explosions, is deflagration...

); however, they burn more slowly than a high explosive which has an extremely fast burn rate.

Low explosives are normally employed as propellants. Included in this group are gun powders and light pyrotechnics
Pyrotechnics
Pyrotechnics is the science of using materials capable of undergoing self-contained and self-sustained exothermic chemical reactions for the production of heat, light, gas, smoke and/or sound...

, such as flares
Flare (pyrotechnic)
A flare, also sometimes called a fusee, is a type of pyrotechnic that produces a brilliant light or intense heat without an explosion. Flares are used for signalling, illumination, or defensive countermeasures in civilian and military applications...

 and fireworks
Fireworks
Fireworks are a class of explosive pyrotechnic devices used for aesthetic and entertainment purposes. The most common use of a firework is as part of a fireworks display. A fireworks event is a display of the effects produced by firework devices...

.

High explosives


High explosives are explosive materials that detonate, meaning that the explosive
Explosion
An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. An explosion creates a shock wave. If the shock wave is a supersonic detonation, then the source of the blast is called a "high explosive"...

 shock front
Shock Front
Shock Front is the first full length album by Converter, released November 22, 1999 . The album is released in two editions, the first featuring a special metal plate packaging , the second featuring a regular cardboard booklet format .-Track listing:# "Conqueror"–8:05# "Shock Front"–7:15#...

 passes through the material at a supersonic
Supersonic
Supersonic speed is a rate of travel of an object that exceeds the speed of sound . For objects traveling in dry air of a temperature of 20 °C this speed is approximately 343 m/s, 1,125 ft/s, 768 mph or 1,235 km/h. Speeds greater than five times the speed of sound are often...

 speed. High explosives detonate with explosive velocity
Explosive velocity
Explosive velocity, also known as detonation velocity or velocity of detonation , is the velocity at which the shock wave front travels through a detonated explosive. The data listed for a specific substance is usually a rough prediction based upon gas behavior theory , as in practice it is...

 rates ranging from 3,000 to 9,000 meters per second. They are normally employed in mining, demolition, and military applications. They can be divided into two explosives classes differentiated by sensitivity
Sensitivity (explosives)
Sensitivity of explosives is the degree to which an explosive can be initiated by impact, heat, or friction.Sensitivity, along with stability and brisance are three of the most significant properties of explosives that affect their use and application. All explosive compounds have a certain amount...

: Primary explosive and secondary explosive. The term high explosive is in contrast to the term low explosive, which explodes (deflagrates) at a slower rate.

Priming composition


Priming compositions are primary explosives mixed with other compositions to control (lessen) the sensitivity of the mixture to the desired property.

For example, primary explosives are so sensitive that they need to be stored and shipped in a wet state to prevent accidental initiation.

By physical form



Explosives are often characterized by the physical form that the explosives are produced or used in. These use forms are commonly categorized as:
  • Pressings
  • Castings
  • Plastic or polymer bonded
    Polymer-bonded explosive
    A polymer-bonded explosive, also called PBX or plastic-bonded explosive, is an explosive material in which explosive powder is bound together in a matrix using small quantities of a synthetic polymer...

  • Putties (AKA plastic explosives)
  • Rubberized
  • Extrudable
  • Binary
  • Blasting agents
  • Slurries and gels
  • Dynamites

Shipping label classifications


Shipping labels and tags may include both United Nations
United Nations
The United Nations is an international organization whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and achievement of world peace...

 and national markings.

United Nations markings include numbered Hazard Class and Division (HC/D) codes and alphabetic Compatibility Group codes. Though the two are related, they are separate and distinct. Any Compatibility Group designator can be assigned to any Hazard Class and Division. An example of this hybrid marking would be a consumer firework, which is labeled as 1.4G or 1.4S.

Examples of national markings would include United States Department of Transportation
United States Department of Transportation
The United States Department of Transportation is a federal Cabinet department of the United States government concerned with transportation. It was established by an act of Congress on October 15, 1966, and began operation on April 1, 1967...

 (U.S. DOT) codes.

United Nations Organization (UNO) Hazard Class and Division (HC/D)



The Hazard Class and Division (HC/D) is a numeric designator within a hazard class indicating the character, predominance of associated hazards, and potential for causing personnel casualties and property damage. It is an internationally accepted system that communicates the primary hazard associated with a substance using the minimum amount of markings.

Listed below are the Divisions for Class 1 (Explosives):
  • 1.1 Mass Detonation Hazard. With HC/D 1.1, it is expected that if one item in a container or pallet inadvertently detonates, the explosion will sympathetically detonate
    Sympathetic detonation
    A sympathetic detonation , also called flash over, is a detonation, usually unintended, of an explosive charge by a nearby explosion. Sympathetic detonation is caused by a shock wave, or impact of primary or secondary blast fragments.The initiating explosive is called donor explosive, the initiated...

     the surrounding items. The explosion could propagate to all or the majority of the items stored together causing a mass detonation. There will also be fragments from the item’s casing and/or structures in the blast area.
  • 1.2 Non-mass explosion, fragment-producing. HC/D 1.2 is further divided into three subdivisions, HC/D 1.2.1, 1.2.2 and 1.2.3, to account for the magnitude of the effects of an explosion.
  • 1.3 Mass fire, minor blast or fragment hazard. Propellants and many of the pyrotechnic items fall into this category. If one item in a package or stack initiates, it will usually propagate to the other items creating a mass fire.
  • 1.4 Moderate fire, no blast or fragment. HC/D 1.4 items are listed in the table as explosives with no significant hazard. Most small arms and some pyrotechnic items fall into this category. If the energetic material in these items inadvertently initiates, most of the energy and fragments will be contained within the storage structure or the item containers themselves.
  • 1.5 mass detonation hazard, very insensitive.
  • 1.6 detonation
    Detonation
    Detonation involves a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations are observed in both conventional solid and liquid explosives, as well as in reactive gases...

     hazard without mass detonation hazard, extremely insensitive.


To see an entire UNO Table, browse Para 3-8 and 3-9 from the NAVSEA OP 5, Vol. 1, Chapter 3.

Class 1 Compatibility Group


Compatibility Group codes are used to indicate storage compatibility for HC/D Class 1 (explosive) materials. Letters are used to designate 13 compatibility groups as follows.

A: Primary explosive substance (1.1A).

B: An article containing a primary explosive substance and not containing two or more effective protective features. Some articles, such as detonator assemblies for blasting and primers, cap-type, are included. (1.1B, 1.2B, 1.4B).

C: Propellant explosive substance or other deflagrating explosive substance or article containing such explosive substance (1.1C, 1.2C, 1.3C, 1.4C). These are bulk propellant
Propellant
A propellant is a material that produces pressurized gas that:* can be directed through a nozzle, thereby producing thrust ;...

s, propelling charges, and devices containing propellants with or without means of ignition. Examples include single-, double-, triple-based, and composite propellants, solid propellant rocket motors and ammunition with inert projectiles.

D: Secondary detonating explosive substance or black powder or article containing a secondary detonating explosive substance, in each case without means of initiation and without a propelling charge, or article containing a primary explosive substance and containing two or more effective protective features. (1.1D, 1.2D, 1.4D, 1.5D).

E: Article containing a secondary detonating explosive substance without means of initiation, with a propelling charge (other than one containing flammable liquid, gel or hypergolic liquid) (1.1E, 1.2E, 1.4E).

F containing a secondary detonating explosive substance with its means of initiation, with a propelling charge (other than one containing flammable liquid, gel or hypergolic liquid) or without a propelling charge (1.1F, 1.2F, 1.3F, 1.4F).

G: Pyrotechnic substance or article containing a pyrotechnic substance, or article containing both an explosive substance and an illuminating, incendiary, tear-producing or smoke-producing substance (other than a water-activated article or one containing white phosphorus, phosphide or flammable liquid or gel or hypergolic liquid) (1.1G, 1.2G, 1.3G, 1.4G). Examples include Flares, signals, incendiary or illuminating ammunition and other smoke and tear producing devices.

H: Article containing both an explosive substance and white phosphorus (1.2H, 1.3H). These articles will spontaneously combust when exposed to the atmosphere.

J: Article containing both an explosive substance and flammable liquid or gel (1.1J, 1.2J, 1.3J). This excludes liquids or gels which are spontaneously flammable when exposed to water or the atmosphere, which belong in group H. Examples include liquid or gel filled incendiary ammunition, fuel-air explosive (FAE) devices, and flammable liquid fueled missiles.

K: Article containing both an explosive substance and a toxic chemical agent (1.2K, 1.3K)

L Explosive substance or article containing an explosive substance and presenting a special risk (e.g., due to water-activation or presence of hypergolic liquids, phosphides, or pyrophoric substances) needing isolation of each type (1.1L, 1.2L, 1.3L). Damaged or suspect ammunition of any group belongs in this group.

N: Articles containing only extremely insensitive detonating substances (1.6N).

S: Substance or article so packed or designed that any hazardous effects arising from accidental functioning are limited to the extent that they do not significantly hinder or prohibit fire fighting or other emergency response efforts in the immediate vicinity of the package (1.4S).

Regulation



The legality of possessing or using explosives varies by jurisdiction.

United States


In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, these acts are governed by the Importation, Manufacture, Distribution and Storage of Explosive Materials (18 U.S.C. Chapter 40).

New York


In the State of New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...

, health and safety regulations restrict the quantity of black powder a person may store and transport.

See also



  • Binary explosive
    Binary explosive
    A binary explosive or two-component explosive is an explosive consisting of two components, neither of which is explosive by itself, which have to be mixed in order to become explosive...

  • Detection dog
    Detection dog
    A detection dog or sniffer dog is a dog that is trained to and works at using its senses to detect substances such as explosives, illegal drugs, or blood. Hunting dogs that search for game and search dogs that search for missing humans are generally not considered detection dogs...

  • Explosive velocity
    Explosive velocity
    Explosive velocity, also known as detonation velocity or velocity of detonation , is the velocity at which the shock wave front travels through a detonated explosive. The data listed for a specific substance is usually a rough prediction based upon gas behavior theory , as in practice it is...

  • Flame speed
    Flame speed
    The flame speed is the measured rate of expansion of the flame front in a combustion reaction. Whereas flame speed is generally used for a fuel, a related term is explosive velocity, which is the same relationship measured for an explosive. Combustion engineers differentiate between the laminar...

  • Improvised explosive devices
  • Nuclear weapon
    Nuclear weapon
    A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...

  • Orica
    Orica
    Orica is a multinational corporation that manufactures various chemical products. It is the largest supplier of mining explosives in the world. -History:...

    ; largest supplier of commercial explosives


External links