Post on 02-Jun-2018
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History, Nature andClassification of High
Explosives
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6. Acetylides -C C
7. Halides of Nitrogen NX 3 (e.g. NI 3)
8. Organometalics R Mg X
Most of the military explosives belongs to nitro class ofcompounds.
Classification of Explosives based on
Chemical Groups (Contd.)
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Nature of High ExplosivesPrimary (InitiatoryExplosives)
- Very sensitive (less stability)
- Undergo very rapid transitionfrom burning to detonation
- Ability to transmit detonation toless sensitive explosives
- Detonate with heat or shock.
- Ex. Mercury fulminate, Leadazide, Silver azide, etc.
Secondary (Military orCivil Explosives)
- Less sensitive (high stability)
- Very powerful than primaryexplosives
- Can be only detonated with heator shock from primary explosives
- Ex. Picric acid, TNT, RDX, HMX,TATB, etc.
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Primary Explosives
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Lead Azide (PbN 6) Composition
Salient FeaturesIt has a good shelf life in dry conditions, but is unstable in the presence of
moisture and oxidising agents.
It is less sensitive to impact than mercury fulminate.
It has high capacity for initiating other secondary explosives to detonation.
PbN
N N
N N
NLead acetate + Sodium azide
(Curtius, 1891)
A major initiating explosive used in all blasting caps and other hot-wiredetonators due to excellent storage characteristics.
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Silver Azide (AgN 3) Composition
Salient FeaturesIt is slightly hygroscopic and is very vigorous initiator. It decomposes under the
influence of ultra-violet irradiation.
If the intensity of radiation is sufficiently high the crystals may explode by
photochemical decomposition.
Silver nitrate + Sodium azide AgN N N
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Tetrazene (C2H
8 N
10O)
Composition
Salient FeaturesIt is slightly hygroscopic and stable at ambient temperatures. It hydrolyses in
boiling water evolving nitrogen gas.
The detonation properties of tetrazene depend on the density of the material.
On compaction it will not detonate. So it is unsuitable for filling detonators.
NN
N
NH
C N N NNH 2
CNH
NH 2Sodium nitrite + Aminoguanidine
Tetrazolyl guanyltetrazene hydrate
. H 2O
(Hoffmann & Roth, 1910)
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Nitroglycerine Composition
CharacteristicsNitroglycerine has advantage over blackpowder as it contains both fuel and oxidizer
elements in the same molecule which gives intimate contact for both components.
Used for difficult mining & tunnelling operations.
Glycerol Nitroglycerine
(Ascanio Sobrero, 1846 &Immanuel Nobel, 1863)
C
C
CH
H
H
H O
O
O
H
NO 2NO 2NO 2
C
C
CH
H
H
H OH
OH
OH
H
Nitration
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Ammonium Nitrate Composition
CharacteristicsThe most common inorganic explosive which is extremely difficult to initiate.
When mixed with other explosives or with fuels in the form of powder, slurry, or
gel mixtures, it becomes an effective an inexpensive commercial explosive for use
in blasting.
NH 3 + HNO 3 (NH 4NO 3)
Ammonia Nitric acid
(Glauber, 1654)
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Picric acid (2,4,6-trinitrophenol) Composition
Characteristics
OH
NO 2
NO 2O 2NOH
Nitration
Phenol
Initially it was used as a dye for silk and wool.
It attacks common metals (Zn, Cu, Fe) and produces very explosive salts.
Its explosive power is superior than TNT.
Picric acid was used in grenade and mine fillings.
(Glauber, 1742 &Turpin, 1885)
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Tetryl
(2,4,6-trinitrophenylmethylnitramine) Composition
Characteristics
NCH 3H3C N
NO 2
NO 2O 2N
H3C NO 2
Nitration
Dimethylaniline (Mertens, 1877)
It is pale, yellow, crystalline solid with melting temp. 129 OC
It is moderately sensitive to initiation by friction.
It was extensively used during World War II.
Tetryl is quite toxic to handle and is therefore replaced by RDX.
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TNT (2,4,6-trinitrotoluene) Composition
Characteristics
CH 3
NO 2
NO 2O 2NCH 3
Nitration
3 step processToluene (Wilbrand, 1863)
It is pale, yellow, crystalline solid with melting temp. 80.8 OC.
It has good chemical and thermal stability and has good compatibility withother explosives.
It has low manufacturing cost and is safe in handling with low sensitivity to
impact and friction.
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Nitroguanidine (Picrite) Composition
Characteristics
HN CNH2
NH
NO 2HN C
NH 2
NH 2
Nitration
Guanidine (Jousselin, 1877)
It is stable below its melting point (232 OC) but decomposes very fast on
melting to form ammonia, water vapor and solid products.
It is also used as propellants as it possesses a low heat and temperature of
explosion.
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PETN (Pentaerythritol tetranitrate) Composition
Characteristics
C
H2C
H2C
H2C
CH2
O
O
O
O
NO 2
NO2
O 2N
O2N
C
H2C
H2C
H2C
CH2
OH
OH
HO
HO
Nitration
Pentaerythritol
It is most stable and least reactive nitric ester explosive.
A powerful secondary explosive and has a great shattering effect therefore,
used in commercial blasting caps, detonation cords and boosters.
It is sensitive to friction and impact and hence mixed with polymer bondedexplosives (PBX).
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RDX(Hexogen/Cyclonite/Cyclotrimethylenetrinitramine)
Composition
Characteristics
CH 2N
CH2
NCH 2
NNO 2
NO 2O 2NN N
N
Nitration
NHexamethylenetetramine
RDX is white crystalline solid with melting temp. 204 OC.
It is chemically and thermally more stable than PETN.
Insensitive explosive compositions containing RDX can be achieved byembedding the RDX crystals in a polymeric matrix as PBX.
(Henning, 1899 &Herz, 1920)
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TATB (triaminotrinitrobenzene) Composition
Characteristics
NH2
NO 2
NO 2O 2N
NH2H2N
Cl
NO 2
NO 2O 2N
ClCl
Cl
ClCl
Nitration Amination
(Jackson and Wing, 1888)
It is a yellow-brown coloured.
It is known as heat-resistant explosive as it has very high melting and
decomposition temp. (350 OC).
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HNS (Hexanitrostilbene) Composition
Characteristics
C CH
H
NO 2 O 2N
NO 2O2N
NO 2 O 2N
CH 3NO 2
NO 2
O 2NNaOCl
Oxidation
It is insensitive to electric spark.
It is resistant to heat as well as radiation. Therefore used in heat-resistant
booster explosives.
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NTO (5-nitro-1,2,4-triazole-3-one) Composition
Characteristics
CHN
HN
C NO 2N
OC
O
HNH2N
NH2
HCl
Semicarbazidehydrochloride
C
HN
HN
CH
N
O NitrationHCOOH
TO NTO
It is a new energetic material having stability greater than RDX. It is
also less sensitive.
NTO is a substitute for ammonium perchlorate or ammonium nitrate in
solid rocket propellants (since it does not liberate undesirable products
such as HCl).
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TNAZ (1,3,3-trinitroazetidine) Composition
Characteristics
O Cl
(Epichlorohydrin)
Multi-stepSynthesis
Fluorochem Process
N
H2C CH 2C
O 2N NO 2
NO 2
It is a white crystalline solid having melting temp. 101 OC.
It has relatively high vapor pressure compared to other explosives.
It forms eutectic mixtures with TNT, Tetryl and HMX.
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