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explosives

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explosive
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explosives

  1. 1. Introduction  An explosive material, also called explosive, is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure.  This potential energy stored in an explosive material may be chemical energy , pressurized gas or nuclear energy.
  2. 2. Classification of Explosives : Primary Explosives Low Explosives High Explosives
  3. 3. Primary Explosives :  Initiating Explosives or detonators.  They are highly sensitive explosives , which explode on receiving a slight shock or by fire. 1. Lead azide : 2. Mercury Fulminate : 3. Tetracene : 4. Diazodinitro phenol :
  4. 4. Low Explosives  They simply burn and do not explode suddenly.  The chemical reactions taking place in such explosives are comparatively slow and their burning proceeds from the surface inward in layers at an approximate rate of 20 cm per second.
  5. 5. Examples : 1. Black powder or gun-powder :  It is a mixture of 75 % potassium nitrate, 15% charcol and 10% sulphur.  Uses : for blasting, in shells, igniters for propellants, practice bombs.
  6. 6. 2. Smokeless powder (nitrocellulose) :  It is prepared by treating cellulose with nitric and sulphuric acids.  It is called smokeless powder because it produces carbon dioxide, carbon monoxide, nitrogen, water vapour and almost no smoke.
  7. 7. High Explosives  They have higher energy content than primary explosives.  They are stable and quite insensitive to fire and mechanical shocks.
  8. 8. Single compound explosives Ammonium nitrate : 2:4:6 – trinitrotoluene (TNT): Pentaerythritol tetranitrate : Cylonite (RDX) :
  9. 9. Binary Explosives  They consist of mixture of TNT with other explosives.  TNT is an important ingredient of these binary explosives, because it has low melting point.  Ex : 1. Amatol: TNT + Ammonium nitrate. 2. pentolite : TNT + PETN, 50% each 3. Tropex : 40% RDX + 40% TNT + 20% Al powder.
  10. 10. Plastic Explosives  Combination of explosives which are in plastic state and can be hand moulded and made into various shapes, without any serious risk.
  11. 11. Dynamites  They are containing of nitroglycerine(NG) as a principal ingedient.  NG is an oily-liquid, which detonates by pressure, shock, or spontaneosly above 50%. 1. Straight-dynamites : 2. Blasting gelatin-dynamites : 3. Gelignite : 65% blasting gelatine + 35% of absorbing powder. It can be used under water.
  12. 12. PREPARATION & APPLICATION OF SOME IMPORTANT EXPLOSSIVES
  13. 13. LEAD AZIDE Pb(N3)2
  14. 14.  It is prepared by reacting aqueous solutions of sodium azide and lead nitrate with each other. 2NaN3 + Pb(NO3)2 = Pb(N3)2 + NaNO3  During the preparation, the formation of large crystals must be avoided, since the breakup of the crystalline needles may produce an explosion.  Accordingly, technical grade product is mostly manufactured which contains 92–96% Pb(N3)2, and is precipitated in the presence of dextrin, polyvinyl alcohol, or other substances which interfere with crystal growth.
  15. 15.  It is used in detonators to initiate secondary explosives.  In a commercially usable form, it is a white to buff powder.  Lead azide is employed as an initiating explosive in blasting caps.  When used as a primary charge, it is effective in smaller quantities than mercury fulminate, has a higher triggering rate, and, unlike mercury fulminate, cannot be dead-pressed by even relatively low pressures.  In order to improve its flammability, an easily flammable additive, such as lead trinitroresorcinate, is added.
  16. 16. MERCURY FULMINATE Hg(CNO)2
  17. 17.  Mercury fulminate is prepared by dissolving mercury in nitric acid, after which the solution is poured into 95% ethanol.  After a short time, vigorous gas evolution takes place and crystals are formed.  When the reaction is complete, the crystals are filtered by suction and washed until neutral.  The mercury fulminate product is obtained as small, brown to grey pyramid-shaped crystals; the color is caused by the presence of colloidal mercury.
  18. 18.  The thermal decomposition of mercury(II) fulminate can begin at temperatures as low as 100 °C, though it proceeds at a much higher rate with increasing temperature.  A possible reaction for the decomposition of mercury(II) fulminate yields carbon dioxide gas, nitrogen gas, and a combination of relatively stable mercury salts. Hg(CNO)2 → 2 CO + N2 + Hg  It was used in compressed form in the manufacture of blasting caps and percussion caps. The material, the shells, and the caps are made of copper.
  19. 19. TRINITROTOLUENE (TNT)
  20. 20.  In industry, TNT is produced in a three-step process. First, toluene is nitrated with a mixture of sulfuric and nitric acid to produce mononitrotoluene (MNT).  The MNT is separated and then renitrated to dinitrotoluene or DNT.  In the final step, the DNT is nitrated to trinitrotoluene or TNT using an anhydrous mixture of nitric acid and oleum.  Nitric acid is consumed by the manufacturing process, but the diluted sulfuric acid can be reconcentrated and reused
  21. 21.  TNT is one of the most commonly used explosives for military, industrial, and mining applications.  TNT has been used in conjunction with hydraulic fracturing, a process used to recover oil and gas from shale formations.  The technique involves displacing and detonating nitroglycerin in hydraulically induced fractures followed by wellbore shots using pelletized TNT  TNT neither absorbs nor dissolves in water, which allows it to be used effectively in wet environments.  Additionally, it is stable compared to other high explosives.  In order to initiate an explosion, TNT must first be detonated using a pressure wave from a more sensitive explosive called an explosive booster.
  22. 22. GUN POWDER
  23. 23.  Gunpowder, also known as black powder, is a chemical explosive—the earliest known. It is a mixture of sulfur, charcoal, and potassium nitrate (saltpeter).  The sulfur and charcoal act as fuels, and the saltpeter is an oxidizer.  Because of its burning properties and the amount of heat and gas volume that it generates, gunpowder has been widely used as a propellant in firearms and as a pyrotechnic composition in fireworks.  Gunpowder is classified as a low explosive because of its relatively slow decomposition rate and consequently low brisance.
  24. 24.  Gunpowder's burning rate increases with pressure, so it bursts containers if contained but otherwise just burns in the open.  A simple, commonly cited, chemical equation for the combustion of black powder is 10 KNO3 + 3 S + 8 C → 2 K2CO3 + 3K2SO4 + 6 CO2 + 5 N2.  Because of its low brisance, black powder causes fewer fractures and results in more usable stone compared to other explosives, making black powder useful for blasting monumental stone such as granite and marble.
  25. 25.  Black powder is well suited for blank rounds, signal flares, burst charges, and rescue-line launches.  Black powder is also used in fireworks for lifting shells, in rockets as fuel, and in certain special effects.
  26. 26. NITROGLYCERIN (NG)
  27. 27.  Nitroglycerine is prepared by running highly concentrated, almost anhydrous, and nearly chemically pure glycerin (dynamite glycerin) into a highly concentrated mixture of nitric and sulfuric acids, with constantly efficient cooling and stirring.  At the end of the reaction the nitroglycerine acid mixture is given to a separator, where the nitroglycerine separates by gravity. Following washing processes with water and an alkaline soda solution remove the diluted residual acid.
  28. 28.  Nitroglycerine is one of the most important and most frequently used components of explosive materials; together with nitroglycol, it is the major component of gelatinous industrial explosives.  In combination with nitrocellulose and stabilizers, it is the principal component of powders, gun propellants and smokeless solid rocket propellants.
  29. 29. PICRIC ACID
  30. 30.  Picric acid is the chemical compound formally called 2,4,6-trinitrophenol (TNP).  This yellow crystalline solid is one of the most acidic phenols.  Its primary use, now outdated, is as an explosive.  It has also been used in medicine (antiseptic, burn treatments), dyes, and as a chemistry agent
  31. 31.  The aromatic ring of phenol is highly activated towards electrophilic substitution reactions, and attempted nitration of phenol, even with dilute nitric acid, results in the formation of high molecular weight tars.  In order to minimize these side reactions, anhydrous phenol is sulfonated with fuming sulfuric acid, and the resulting p-hydroxyphenylsulfonic acid is then nitrated with concentrated nitric acid.  During this reaction, nitro groups are introduced, and the sulfonic acid group is displaced.  The reaction is highly exothermic, and careful temperature control is required.
  32. 32.  By far, the largest use has been in explosives.  Explosive D aka Dunnite is the ammonium salt of picric acid, more powerful but less stable than the more common explosive TNT (which is produced in a similar process to picric acid but with toluene )
  33. 33. PENTAERYTHRITOL TETRANITRATE (PETN)
  34. 34.  Production is by the reaction of pentaerythritol with concentrated nitric acid to form a precipitate which can be recrystallized from acetone to give processable crystals.
  35. 35.  The most common use of PETN is as an explosive with high brisance.  It is more difficult to detonate than primary explosives, so dropping or igniting it will typically not cause an explosion (at atmospheric pressure it is difficult to ignite and burns relatively slowly), but is more sensitive to shock and friction than other secondary explosives such as TNT  It is rarely used alone, but primarily used in booster and bursting charges of small caliber ammunition, in upper charges of detonators in some land mines and shells, and as the explosive core of detonation cord.  PETN is the least stable of the common military explosives, but can be stored without significant deterioration for longer than nitroglycerin or nitrocellulose.
  36. 36. RESEARCH DEPARTMENT FORMULA X / RDX / CYCLONITE
  37. 37. CYCLOTRIMETHYLENE- TRINITRAMINE
  38. 38.  It is a colourless solid, of crystal density 1.82 g/cm3.  It is obtained by reacting white fuming nitric acid (WFNA) with hexamine, producing dinitromethane and ammonium nitrate as byproducts (CH2)6N4 + 3HNO3 → (CH2-N-NO2)3 + NH3+ 3 H2O
  39. 39.  RDX was widely used during World War II, often in explosive mixtures with TNT.  RDX was used in one of the first plastic explosives.  RDX is believed to have been used in many bomb plots including terrorist plots.  RDX forms the base for a number of common military explosives.  Outside military applications, RDX is also used in controlled demolition to raze structures
  40. 40. BLASTING FUSES
  41. 41. A fuse is, a thin water proof canvas length of tube containing gun powder(or TNT) arranged to burn at a given speed for setting off charges of explosives.
  42. 42. SAFETY FUSE  A major contributor to progress in the use of explosives was William Bickford in 1831 he conceived the safety fuse: a core of black powder tightly wrapped in textiles, one of the most important of which was jute yarn.  The present-day version is not very different from the original model. The cord is coated with a waterproofing agent, such as asphalt, and is covered with either textile or plastic.  Once ignited, safety fuses will burn underwater, and have no external flame that might ignite methane or other fuels such as might be found in mines or other industrial environments.  Safety fuses are manufactured with specified burn times per 30 cm, e.g. 60 seconds, which means that a length of fuse 30 cm long will take 60 seconds to burn.
  43. 43. DETONATING FUSE  It is a thin, flexible plastic tube usually filled with pentaerythritol tetra nitrate (PETN).  With the PETN exploding at a rate of approximately 4 miles per second, any common length of detonation cord appears to explode instantaneously.  It is a high-speed fuse which explodes, rather than burns, and is suitable for detonating high explosives. The velocity of detonation is sufficient to use it for synchronizing multiple charges to detonate almost simultaneously even if the charges are placed at different distances from the point of initiation.  It is used to reliably and inexpensively chain together multiple explosive charges. Typical uses include mining, drilling, demolitions, and warfare.
  44. 44. ROCKET PROPELLENTS
  45. 45.  Rocket propellant is a material used by a rocket as, or to produce in a chemical reaction, the reaction mass (propulsive mass) that is ejected, typically with very high speed, from a rocket engine to produce thrust, and thus provide spacecraft propulsion.  A chemical rocket propellant undergoes exothermic chemical reactions to produce hot gas.  There may be a single propellant, or multiple propellants; in the latter case one can distinguish fuel and oxidizer.  The gases produced expand and push on a nozzle, which accelerates them until they rush out of the back of the rocket at extremely high speed.  For smaller attitude control thrusters, a compressed gas escapes the spacecraft through a propelling nozzle.
  46. 46. CHARACTERISTICS OF GOOD PROPELLENTS
  47. 47.  should have high specific impulse that is the propellant should produce greater thrust (downward force or push) per second for 1 kg of the fuel burnt.  should produce high temperatures on combustion.  should produce low molecular weight products during combustion and should not leave any solid residue after ignition.  should burn at a slow and steady rate (that is predictable rate of combustion).  should possess low ignition delay (that is it should burn as soon as it is lighted up).  should possess high density to minimize container space.
  48. 48.  should be stable at a wide range of temperatures.  should be safe for handling and storage.  should be readily ignitable at predictable burning rate.  should leave no solid residue after ignition.  should not be corrosive and hygroscopic(ability to attract and hold water molecules).  should not produce toxic gases or corrosive gases during combustion.
  49. 49. What is propellants ??? A propellant is a chemical substance used in the production of energy or pressurized gas that is subsequently used to create movement of a fluid or to generate propulsion of vehicle, projectile, or other object. Technically, the word propellant is the general name for chemicals used to create thrust.
  50. 50. Classifications of propellants We have main two types of propellants. (1)Solid propellant may be (a) Homogeneous (b) Heterogeneous (1) Liquid propellant may be (a) monopropellant (b) bipropellant
  51. 51. Homogeneous solid propellant When solid propellant or a mixture of propellant is thoroughly mixed in a colloidal state , its called homogeneous solid propellant. cv When a single propellant is employed , it is called a single-base propellant . Nitro-cellulose , also known as gun-cotton or smokeless powder. A solid propellant which contains two materials , is called double-base propellant . Ballisite , containing nitrocellulose and nitroglycerin mixture is a powerful double base propellant .
  52. 52. Heterogenus solid propellant When an oxidising agent is dispersed in a fuel mass , the solid propellant is called heterogeneous or composite . Gun powder is the oldest composite propellant . It gives a flame temperature of 800-1500 °c and the volume of the gases Is about 400 times the volume of the charge .
  53. 53. Liquid propellants Liquid propellants possess many advantages over the solid propellants. Thus , liquid propellants are more versatile and the engine using them can be checked and calibrated more easily . Monopropellant : A Monopropellant has fuel as well as oxidiser in thus same molecule or in a solution containing both these . A Monopropellant must be safe to store and at the same time , it should burn smoothly . Hydrogen peroxide , nitro methane are common monopropellants .
  54. 54. Bipropellants : Bipropellants are more widely used . In these , liquid fuel plus oxidiser , kept separately , are injected in the combustion chamber separately . Liquid hydrogen , hydrazine ,ethyl alcohol are common Bipropellant .

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