Environmental Engineering Reference
In-Depth Information
the energy is lost in the process of formation of molecule, its formation heat is
relatively large. Therefore,
the structure of explosive molecule has signi
cant
impact on its explosion energy.
(2) Introduction of some high-energy elements into the explosive molecule
Generally, combustible agent boron (B) or oxidant
fl
fluorine (F) are introduced in
the explosive to form new compounds. The in
fl
uence of introduced high-energy
elements can be
figured out roughly from that data listed in Table 3.8 , in which
energy of the boron-containing compound is the highest.
(3) Addition of
fine metal powder of high-calorie oxide, such as aluminum
powder, magnesium powder, and boron powder
A right amount of aluminum powder is added into RDX, its explosion heat can
be increased by 50 % because the added aluminum not only can react with oxygen
with large amount of released heat as the following:
2Al
þ
1
:
5O 2 !
Al 2 O 3 þ
1669
:
42 kJ or 16401
:
28 J
=
g
but also react with explosion products CO 2 and H 2 O secondarily as the following:
2Al
þ
3CO 2 !
Al 2 O 3 þ
3CO
þ
593
:
29 kJ
=
mol
2Al
þ
3H 2 O
!
Al 2 O 3 þ
3H 2 þ
943
:
91 kJ
=
mol
Because there is large amount of heat released, it can continue to maintain its
explosion pressure.
The reaction level of aluminum depends on its particle size and the scattering
conditions of explosion products. The decrease of aluminum powder grain size can
increase the stability of explosive detonation, but it can cover other particles to
hinder the reaction transmission if its size is too small. The typical used aluminum
particle is 3
m in diameter. Since aluminum are oxidized during its secondary
reaction with oxygen-containing gas products from the
200
ʼ
-
first stage of explosion, the
temperature of gas explosion products, the distribution of unreacted aluminum
particles in the product, and the extended phase-contacting time all play important
roles in the reaction level of aluminum powder.
Generally, in
uence of the aluminum powder added into explosive components
on the explosion velocity is not signi
fl
cant. However, because aluminum powder
Table 3.8 Thermochemistry data of products from combustion and explosion
Product
Explosion heat Qf f (kJ)
Formula weight
Heat per unit mass (J/g)
B 2 O 2 (s)
1263.57
69.6
18744.32
HF(g)
268.60
20
13430.64
H 2 O(g)
239.66
18
13430.64
CO 2 (g)
395.43
44
8995.6
CF 4 (g)
679.90
88
7740.4
CO(g)
112.47
28
4016.64
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