136 Propellants, Explosives, Pyrotechnics 27, 136 Ä… 141 (2002)
Performance Parameters of Explosives: Equilibrium
and Non-Equilibrium Reactions
Fred Volk and Helmut Bathelt
Fraunhofer-Institut f¸r Chemische Technologie ICT, Joseph-von-Fraunhofer-StraÚe 7,
D-76327 Pfinztal (Germany)
Dedicated to Professor Dr. Hiltmar Schubert on the Occasion of his 75th Birthday
Summary The followingcontribution shows under which precondi-
tions the thermodynamic calculations lead to a good agree-
For the calculation of the performance parameters of combus-
ment between theory and experiment. But it also points out
tion processes, equilibrium thermodynamic processes are taken
the limit of the calculation of reactions, which are very
into account. On the other hand, non-equilibrium reactions occur,
strongly dependent on the pressure, so that non-equilibrium
mostly connected with low pressure burning. In this paper, several
reactions occur. In this case we have to analyze the reaction
explosives, explosive mixtures, solid and liquid propellants have
been calculated. It is shown how energy output and gas formation products using experimental methods, or we have to
depend on the oxygen balance and the enthalpy of formation. It
measure the energy output with calorimetric methods.
was found that the reason for the higher specific energy of liquid
propellants is due to the increased formation of gases consisting of
H2, N2 and H2O, compared with conventional solid propellants
2 Thermodynamic Calculations with the ICT-
based on nitrocellulose and nitroglycerin, which produce more
CO and CO2. Non-equilibrium combustion of solid propellants
Thermodynamic Code
was found at very low loading densities or pressures lower than 1
to 2 MPa. In this case, the reaction products measured by mass
The ICT-Thermodynamic Code is based on a method
spectrometry, such as NO, N2O and HCN, are metastable and
developed by the National Space Administration (NASA)(1,2).
highly toxic, producing a much lower heat of explosion compared
with equilibrium burning measured and calculated.
This method uses mass action and mass balance expressions
to calculate chemical equilibria. Thermodynamic equilibria
can be calculated for constant pressure conditions as well as
for constant volume conditions.
1 Introduction
In addition to the equation of state (EOS) for an ideal gas,
the virial EOS can be used and is necessary for the high-
A precise knowledge of the combustion processes of pressure conditions of guns and closed vessels(3, 4). The
energetic materials is important since the reaction process calculation of the heat of explosion is of special interest,
determines the energy output and other parameters such as because the experimental measurement of the heat using
the closed vessel technique is sometimes difficult due to high
*
Enthalpy of reaction
temperatures and erosive reaction products.
*
Specific energy
Finally, the code can be used to determine the parameters
*
Specific impulse
of gas detonations, e.g. pressure, temperature and detona-
*
Reaction temperature and pressure
tion velocity.
*
Reaction products and gas formation and therefore the
The enthalpies of formation, which are necessary for
degree of the toxicity of the products.
thermodynamic calculations, are contained in the ICT-
For the theoretical verification of the combustion behav- Thermochemical Data Base(5).
ior of energetic materials computer codes are widely used,
which evaluate the reaction energy and products on the basis
of thermodynamic equilibrium calculations. 2.1 Calculated Results of Several Explosives at Constant
Under the aspect of a critical application of the codes, it is Volume Conditions
possible to determine not only the combustion energy of a
number of explosives, but also the reaction products For the thermodynamic calculations of energetic materi-
quantitatively, especially by considering the freeze out als we usually need the composition and the enthalpy of
reactions of the products. On the other hand, it is possible to formation. Then it can be decided if the calculation should
avoid some toxic products by optimizingthe components of be for conditions of a constant volume or of a constant
the propellant or gas generator. pressure. The main advantage for a constant volume
Ä… WILEY-VCH Verlag GmbH, 69469 Weinheim, Germany, 2002 0721-3113/02/2701-0136 $ 17.50+.50/0
Propellants, Explosives, Pyrotechnics 27, 136 Ä… 141 (2002) Performance Parameters of Explosives 137
calculation is that we can evaluate the heat of explosion. (‡ 19.98%) or ammonium dinitramide (ADN) with
This holds for a loading density of 0.1 g/cm3. This value ‡ 25.8%. For glycoldinitrate, the oxygen balance is zero.
can also be measured experimentally in a calorimetric In Table 1 the highest values for the specific energy, the
bomb system at the same loading density. This way it is heat of explosion and even the adiabatic temperature are
possible to compare measured and calculated heats of produced during the combustion of substances having a
explosion. positive or a small negative oxygen balance. But with the
Usually, combustion reactions not only depend on the more negative oxygen balance, the energy decreases and the
enthalpy of formation. In many cases, the oxygen balance of mole number increases. This means that the gas formation of
the energetic component or the mixture influence much a more negative oxygen balance is higher than for a better
more the energy-output and the gas formation. Table 1 oxygen balance.
contains the results of the calculations of several explosive Therefore, it can be understood that the combustion of
substances with different oxygen balances. substances with a very negative oxygen balance such as
The oxygen balance is defined as the amount of oxygen benzene derivatives cannot be complete: The more CO and
expressed in weight percent liberated as a result of a complete H2 is formed, with a decrease of CO2, the higher is the
conversion of the explosive material to CO2, H2O, SO2, Al2O3 probability of a formation of free carbon (see Table 1). In
etc. (positive oxygen balance). If the amount of oxygen is the same direction, temperature, pressure and both energy
insufficient for the complete oxidation reaction (negative parameters are also decreasing.
oxygen balance), the deficient amount of oxygen needed to The specific energy (ES) can also be evaluated from
complete the reaction is reported with a negative sign. measurements in a ballistic vessel. Its definition is:
Only a few explosives exhibit a positive oxygen balance,
such as nitroglycerin (‡ 3.5%), ammonium nitrate ES ˆ n R TEX
Table 1. Influence of oxygen balance on energy parameters of explosives.
Explosive DHf O2-Balance Temperature Pressure Specific Heat of Mole Carbon
kJ/kg % K MPa Energy Explosion number weight%
J/g J/g mol/kg
ADN 1 207. ‡ 25.8 2 514 92.6 843 3 337 40.30 Ä…
Nitroglycerin 1 632. ‡ 3.5 3 887 124.0 1 125 6 671 31.91 Ä…
Glycol dinitrate 1 596. 0.0 3 941 131.3 1 190 7 289 32.88 Ä…
Hexanitrobenzene ‡ 420.7 0.0 4 509 128.3 1 154 7 203 25.85 Ä…
Nitropenta 1 705. 10.1 3 953 133.3 1 205 6 306 34.79 Ä…
CL-20 ‡ 921. 10.9 4 347 147.9 1 323 6 312 34.22 Ä…
Pentanitrobenzene 162.9 13.2 4 469 134.5 1 206 6 094 29.69 Ä…
BTTN 1683. 16.6 3 917 139.0 1 254 6 022 37.28 Ä…
TNAZ ‡ 189.5 16.7 4 263 151.5 1 358 6 343 36.39 Ä…
RDX ‡ 301.4 21.6 4 000 154.1 1 375 5 647 40.26 Ä…
NTO 775. 24.6 2 956 106.4 945 3 148 38.12 Ä…
NC 13.4%N 2 390. 29.2 3 388 121.8 1 094 4 409 38.30 Ä…
Nitroguanidine 893. 30.7 2 335 105.7 932 3 071 46.47 Ä…
1,2,3,5-Tetranitrobenzene ‡ 142.8 31.0 4 298 143.1 1 277 4 941 34.73 Ä…
1,2,3,4-Tetranitrobenzene ‡ 300.2 31.0 4 374 146.1 1 304 5 098 34.73 Ä…
TAGN 287.9 33.5 2 593 132.1 1 159 3 974 51.90 Ä…
NC 12.6%N 2 598. 34.5 3 085 115.7 1 037 3 983 39.69 Ä…
Metriol trinitrate 1 666. 34.5 3 497 140.9 1 260 5 053 42.19 Ä…
Nitromethane 1 853. 39.3 3 043 139.7 1 245 4 821 47.25 Ä…
DEGN 2 227. 40.8 3 083 132.0 1 178 4 566 44.20 Ä…
NC 11.6%N 2 859. 41.2 2 683 106.3 949 3 480 41.17 Ä…
PVN 1 152. 44.9 3 388 143.0 1 269 4 781 42.76 Ä…
Tetryl 69.9 47.4 3 468 137.0 1 208 4 271 40.27 2.2
TATB 541.4 55.8 2 218 96.1 838 3 062 43.85 4.9
Trinitroaniline 368.1 56.1 2 663 109.6 960 3 589 42.26 5.8
1,3,5-Trinitrobenzene 204.2 56.3 3 017 119.6 1 050 3 963 41.18 6.33
1,2,3-Trinitrobenzene ‡ 25.5 56.3 3 193 126.6 1 112 4 193 41.18 6.4
Triethyleneglycol dinitrate (TEGN) 2 619. 66.6 2 025 102.5 899 3 317 47.50 Ä…
2,4,6-TNT 295.3 74.0 2 512 103.3 908 3 766 46.13 11.2
Z-Tacot ‡ 1188. 74.2 3 086 103.6 924 4 121 45.68 16.2
1,3-Dinitrobenzene 161.8 95.2 2 304 88.1 782 3 519 50.82 19.2
Isopropyl nitrate 2 187. 99.0 1 723 92.7 803 3 126 53.86 4.1
Nitrobenzene ‡ 78.9 162.4 1 771 59.0 537 2 871 66.12 40.0
Propylene oxide 2 111. 220.4 1 371 56.6 517 2 415 74.67 35.2
138 F. Volk and H. Bathelt Propellants, Explosives, Pyrotechnics 27, 136 Ä… 141 (2002)
Table 2. Energy parameters of CL20 with different amounts of PB.
Explosive DHf O2-Balance Temperature Pressure Spec. Energy Heat of Explosion Mole number Carbon
CL20/PB kJ/kg % K MPa J/g J/g mol/kg weight %
(weight %)
100/0 920.5 10.95 4 347 147.9 1 323 6 312 34.22 Ä…
95/5 898.9 26.4 4 206 156.5 1 392 5 453 38.52 Ä…
90/10 877.4 41.8 3 751 155.0 1 366 4 780 41.28 Ä…
85/15 855.8 57.2 3 167 145.0 1 263 4 579 44.66 3.8
80/20 834.3 72.7 2 695 125.3 1 091 4 435 48.23 8.3
75/25 812.8 88.1 2 517 116.5 1 018 4 288 51.70 12.6
70/30 791.2 103.5 2 355 108.3 949 4 138 55.08 16.8
65/35 769.7 119.0 2 210 100.5 884 3 985 58.37 20.9
60/40 748.1 134.4 2 083 93.3 824 3 829 61.58 24.9
55/45 726.6 149.8 1 973 86.7 769 3 670 64.71 28.9
Table 3. Energy output of different solid propellants.
Name O2-Balance T P ES n QEX
% K MPa J/g mol/kg J/g
JA-2 30.35 3 397 127.1 1 141 40.39 4 622
A 5020 39.67 2 916 113.1 1 011 41.70 3 759
M1 50.52 2 494 103.9 921 44.40 3 247
P 544 51.88 2 009 90.7 799 47.83 2 841
KHP 305 35.49 3 522 151.5 1 338 45.69 4 828
KHP 168 55.61 2 180 107.3 933 51.46 3 281
RDX 21.6 4 000 154.1 1 375 40.26 5 647
TNAZ 16.6 4 263 151.5 1 358 36.39 6 343
CL 20 10.9 4 347 147.9 1 323 34.22 6 312
This means that the specific energy is proportional to the This behavior is typical for the combustion of energetic
gas formation n and the adiabatic temperature TEX. materials: In many cases it is known from experimental
investigations that carbon soot is formed from materials
with an oxygen balance more negative than 55 %. But the
combustion of energetic materials is very different from
2.2 Energy of CL20 with Different Amounts of PB-Binder detonation processes(6). In the case of a detonation, much
higher pressures will occur. They are about 34 GPa for RDX
The relationship between the oxygen balance and the and about 19 GPa for TNT. Therefore, a lot of the produced
energy parameters on the one hand and the gas formation on carbon monoxide (CO) reacts according to the Boudouard
the other hand will be much more clear when the calculated equilibrium under the formation of carbon soot and CO2:
results of the energetic substance hexanitrohexaazaisowurt-
zitane (CL20) with different amounts of a polybutadiene 2CO, CO2 ‡ C DH ˆ 172.4 kJ/mol
binder (PB) are compared.
Table 1 and Table 2 show that pure CL20 is more Therefore, the carbon soot formation in detonation
energetic than RDX regarding the temperature and the processes is much higher than in combustion processes.
heat of explosion. On the other hand, combustion pressure Because of the high energy output of the Boudouard
and specific energy of RDX are higher. The reason for this reaction, also the detonation heat is higher than the heat of
behavior is the oxygen balance, which is much more combustion.
negative for RDX. Therefore, RDX produces more gas
than CL20, which increases the product n R TEX to a
higher value of the specific energy, despite the fact that the 2.3 Energy of Solid Propellants
adiabatic temperature of RDX is lower.
Together with the PB-binder, the oxygen balance and the In connection with the performance of solid propellants,
enthalpy of formation decrease more and more connected the energy output of some gun propellants is shown in
with a decrease in pressure, temperature and the energy Table 3. With decreasing oxygen balance, the energy and the
parameters. Only the mole number and therefore the gas gas formation of four conventional propellants are com-
formation increase. In addition, starting at an oxygen pared with two nitramine containingpropellants.
balance of about 57 %, the combustion reaction produces
more and more carbon soot.
Propellants, Explosives, Pyrotechnics 27, 136 Ä… 141 (2002) Performance Parameters of Explosives 139
Table 4. Liquid explosives.
DHf O2-Balance Temperature Pressure Spec. Energy Heat of Explosion Mole number
kJ/kg % K MPa J/g J/g mol/kg
N2H4 /N2O4 683.6 15.15 3 725 183.5 1 636 6 822 52.10
50/50
UDMH/N2O4 151.6 29.33 3 818 172.6 1 536 6 246 46.87
35/65
MMH/HNO3 1384 19.51 3 496 157.2 1 414 6 076 48.03
35/65
TEA/HNO3 3362 20.7 3 159 125.5 1 137 4 973 43.0
35/65
NOS 365 6144 0.01 2 480 98.1 916 4 647 44.28
HAN/IPAN/H2O
60.7/19.3/20.0
Conventional propellants So, nitramine propellants with GAP-binders exhibit a
quite high energy, much higher than the conventional
*
JA-2 Double base propellant
propellants based on nitrocellulose, nitroglycerin or nitro-
*
A 5020 Single base propellant
guanidine.
*
M1 Single base propellant
Even for explosives with the highest energy output, such
*
P544 Triple base propellant with nitroguanidine (Nigu).
as 1,3,3-Trinitroazetine (TNAZ) or Hexanitrohexaazaiso-
Nitramine containingpropellants wurtzitane (CL20), the specific energies of the pure
substances are quite similar to the GAP containing nitr-
*
KHP 305 79% RDX, 8.0% TAGN, 13.0% GAP binder,
amine propellant KHP 305, as it is shown in Table 3.
*
KHP 168 42.5% RDX, 42.5% Nigu, 4% KNO3,
11% Polybutadiene binder (PB).
In addition, the energy parameters of RDX, TNAZ (1,3,3- 2.4 Energy of Liquid Propellants
Trinitroazetidine) and CL20 are listed in Table 3.
With the decrease of the temperature and of the specific It is well known that liquid propellants increase the energy
energy the gas formation (mole number n) increases. It is of output markedly (Table 4). High specific energies and heats
interest that the nitramine propellant KHP 305 containing of explosion are produced from the hypergolic liquid
RDX and a GAP binder exhibits a much higher specific propellants with hydrazine (N2H4) and unsymmetric dime-
energy (1 338 J/g) than the double base propellant JA-2 thylhydrazine H2N N(CH3)2 (UDMH) as fuels and nitrogen
(1 141 J/g). On the other hand, the same composition with tetroxide (N2O4) as an oxidizer.
respect to RDX and TAGN, but with a polybutadiene binder The followingspecific energies are calculated:
instead of the GAP binder, produces a much lower specific
energy and heat of explosion. The reason for this behavior is 50% N2H4/ 50% N2O4: 1 636 J/g
that the Glycidylazide Polymer (GAP) has a better oxygen 35% UDMH/50% N2O4: 1 536 J/g.
balance ( 121.1%) and a more positive enthalpy of
formation (Hf ˆ‡141.0 kJ/mol), compared with the poly- These energy values are higher than the highest energies
butadiene HTPB: oxygen balance ˆ 317.6% and Hf ˆ from solid propellants. It may be reminded that the rocket
‡ 2.93 kJ/mol. motor of the Apollo 11 Spacecraft Vehicle landing on the
Table 5. Combustion products of MMH/HNO3 compared with the gun propellant JA-2 (Loading density: 0,1 g/l).
MMH/HNO3 JA-2
Analysis Calculation Calculation
Oxygen balance in % 30.0 30.0 30.35
Composition in Vol%
H2 21.5 22.3 13.6
N2 26.1 25.9 12.6
CH4 0.7 0.9 0.6
CO 10.4 10.2 31.8
CO2 4.7 5.6 18.8
H2O 36.6 34.8 22.5
Heat of Explosion QEX (J/g) 5 583 4 609
Spec. Energy ES (J/g) 1 403 1 139
Mole number n (mol/kg) 52.52 40.39
Mean molecular weight (g/mol) 19.04 24.76
Enth. of Formation (kJ/kg) 1 209 2 290
140 F. Volk and H. Bathelt Propellants, Explosives, Pyrotechnics 27, 136 Ä… 141 (2002)
Table 6. Gas generator optimisation.
5-ATZ/KNO3 O2-Balance Temperature Heat of Explosion Mole number CO H2 NO
(Weight%) % K J/g mol/kg mol% mol% mol%
47.00/53.00 10 2 070 3 290 32.73 6.90 13.25 Ä…
42.28/57.72 5 2 184 3 536 30.46 3.86 7.34 Ä…
38.49/61.51 1 2 291 3 739 28.59 0.85 1.59 Ä…
37.54/62.46 0 2 300 3 790 28.13 0.001 0.001 0.001
36.59/63.41 ‡ 1 2 207 3 664 27.85 Ä… Ä… 0.027
32.80/67.20 ‡ 5 1 843 3 161 26.44 Ä… Ä… 0.061
28.05/71.95 ‡ 10 1 780 2 473 22.51 Ä… Ä… 0.085
moon in July 1969 used UDMH and N2O4 as rocket 3 Non-Equilibrium Combustion Reactions
propellants.
The specific energies of these liquid propellants are even Contrary to equilibrium reactions, it is not possible to
higher than those of gun propellants with a similar oxygen calculate non-equilibrium processes using thermodynamic
balance because of the higher amount of reaction products codes, and for the reaction kinetic procedures, there are not
such as H2, N2 and H2O, and less carbon dioxide. In addition, enough correct data for the many reaction rate constants,
a less negative enthalpy of formation leads to a higher heat which we need for a complete calculation of the reaction
of explosion (Table 5). products. Therefore, it is necessary to analyze the combus-
Also other fuels such as monomethylhydrazine (MMH) tion products.
and triethanolamine (TEA) together with nitric acid A lot of investigations have been carried out at the
(HNO3) as an oxidizer develop quite high energies, see Fraunhofer ICT to learn about the products of propellants,
Table 4. especially formed by low pressure burning(10). As an
The last liquid propellant system in Table, 4 NOS 365, example, the reaction behavior of the double base propel-
consistingof hydroxylammoniumnitrate (HAN), isopropyl- lant JA-2 was investigated by burning under different
ammonium nitrate (IPAN) and water is of interest, because pressures (Table 7), first by burning in a closed vessel with
it was tested for a long time as a liquid gun propellant(7, 8). a loading density of 100 g/l (high pressure burning), then by
This fuel combination has the main advantage that only CO2, burning with a low loading density of 0.66 g/l. The high
N2 and water are produced duringthe combustion, without loading density of 100 g/l leads to a reaction pressure of
formation of toxic CO. more than 120 MPa (see also Table 3), compared with only a
few MPa for the loadingdensity of 0.66 g/l. As a result, very
different reaction products have been analyzed.
2.5 Optimization of Gas Generators for Airbag Systems Of special interest is the analysis of the product gas, which
was done by mass spectrometry and gas chromatography.
Gas generators for airbag systems have to fulfill special The low-pressure products are very different from the high
requirements with respect to the quality of the combustion pressure burning, which is very similar to the calculated gas
products. Especially, the amount of toxic components has to composition: A high concentration of NO (18.9 mol%),
be minimized and it has to correspond to the official limits. HCN (1.1 mol%), and carbon soot (13.5 mol%), which are
Therefore, it is very helpful to reduce those toxic products,
which can be calculated very accurately such as the CO and
Table 7. Reaction products of double base GP JA-2.
NOX by optimization of the fuel/oxidizer ratio at the
manufacturing process(9).
(O2-Balance: 30.2%) Experiment Calculation
Table 6 makes clear, how the CO content in the reaction
Loading Density [g/l] 0.66 100 100
products of an airbag propellant consisting of 5-amino-
Combustion Condition 0.1 MPa Closed Ä…
tetrazole (5-ATZ) and potassium nitrate (KNO3) can be
Vessel
minimized only by changing the fuel/oxidizer ratio. The
Products [mol%]:
oxygen balance is of great influence on the formation of CO,
H2 3.5 14.0 13.6
H2 and NO. Increasingof the KNO3 content, i.e. improving
CH4 1.0 Ä… 0.7
the oxygen balance, the content of CO and H2 decreases CO 24.9 32.7 31.2
CO2 7.0 17.0 19.0
very strongly. After attaining the minimum of CO a further
N2 1.3 12.4 12.6
increase of the oxygen balance to positive values increases
NO 18.9 0.025* Ä…
the formation of NO.
HCN 1.1 Ä… 0.004
Therefore, it is very important to meet special limits with
NH3 0.8 Ä… 0.08
H2O 28.0 23.4 22.9
regard to the fuel/oxidizer ratio during the manufacturing of
C 13.5 0.5 Ä…
solid
the propellants for gas generators. Nevertheless, it is very
QEX [J/g] 2 488 4 550 4 719
important to measure all the toxic products experimentally
by usingspecial trace analysis detectors. * (NO)X-Analyzer
Propellants, Explosives, Pyrotechnics 27, 136 Ä… 141 (2002) Performance Parameters of Explosives 141
Table 8. Reaction products of KHP 305.
investigated liquid propellants exhibit a higher specific
energy than the conventional solid propellants based on
(O2-Balance: 36.3%) Experiment Calculation
nitrocellulose and nitroglycerin. The reason was the in-
Loading Density [g/l] 0.67 100 100
creased formation of H2, N2 and H2O producingmuch more
Combustion Condition 0.1 MPa Closed Ä…
gas with a lower mean molecular weight.
Vessel
It was also shown that the ICT-Code is very useful for the
Products [Mol %]:
optimization of gas generators for airbag systems, especially
H2 17.8 23.3 21.79
to avoid toxic products.
CH4 0.3 0.3 Ä…
In addition, it was explained that the limits of thermody-
CO 24.5 28.6 27.45
namic calculations are burningreactions at low pressures. In
CO2 5.3 5.4 6.01
N2 27.9 30.9 31.01
this case, a non-equilibrium burning is responsible for the
NO 3.6 Ä… Ä…
formation of toxic metastable reaction products, such as NO,
HCN 4.7 Ä… 0.02
N2O, HCN etc. These products are the reason that the
C2H2 0.1 Ä… Ä…
energy output is much lower than in the case of an
NH3 0.1 Ä… 0.32
H2O 15.7 11.5 13.39 equilibrium burningat pressures higher than 1 to 2 MPa.
QEX [J/g] 4 108 4 409 4 642
5 References
typical for non-equilibrium products. There is also a large
(1) F. J. Zeleznik, S. Gordon, "!An Analytical Investigation of
difference in the heats of explosion: 2 488 J/gcompared with
Three General Methods of Calculating Chemical Equilibrium
4 550 J/g. These values have been calculated from the
Compositions+", NASA-TN D-473, 1960.
difference of the enthalpies of the reaction products and
(2) F. J. Zeleznik, S. Gordon, "!A General IBM 704 or 7090
the propellant components. Computer Program for Computation of Chemical Equilibri-
um Compositions, Rocket Performance, and Chapman-Jou-
A similar influence of the combustion pressure on the
guet Detonations+", NASA-TN D-1454, October 1962.
reaction products was found for other propellants and
(3) F. Volk, H. Bathelt, and H. Hornberg, "!Application of the
explosives such as single base and triple base propellants,
Virial Equation of State in Calculating Interior Ballistics
but also for all the nitramine containingpropellants(11).
Quantities+", Propellants and Explosives 1, 7 Ä… 14 (1976).
An example of non-equilibrium combustion of the nitr- (4) "!The ICT-Thermodynamic Code (ICT-Code), User×s Man-
ual+", Report 200626-7, June 2000, Fraunhofer-Institut f¸r
amine containingpropellant KHP 305 with a GAP binder is
Chemische Technologie (ICT), D-76318 Pfinztal.
recorded in Table 8. Also in this case, metastable reaction
(5) H. Bathelt, F. Volk, and M. Weindel, "!The ICT-Database of
products such as NO and HCN have been produced under
Thermochemical Values, Sixth Update, 2001+", Fraunhofer-
the low combustion pressure of the loadingdensity 0.67 g/l, Institut f¸r Chemische Technologie (ICT), D-76318 Pfinztal.
(6) F. Volk, F. Schedlbauer, "!Analysis and Post Detonation Products
whereas the high pressure burning with 100 g/l exhibits only
of Different Explosive Charges+", IVth Seminar New Trends in
main products such as H2, N2, CO, CO2 and H2O, which are
Research of Energetic Materials, University of Pardubice, Faculty
typical products of the water gas equilibrium
of Chemical Technology, April 11 Ä…12, 2001, pp. 352-359.
(7) C. S. Leveritt, N. Klein, "!The Physical Properties and
Molecular Structure of the HAN-Based Liquid Gun Propel-
CO‡ H2O , CO2 ‡ H2 DH ˆ 41.03 kJ/mol
lants+", 22nd Int. Annual Conference of ICT, Karlsruhe,
Germany, July 2 Ä… 5, 1991, pp. 74/1 Ä… 10.
In another study with the aim to evaluate the combustion
(8) N. Klein, C. S. Leveritt, "!The Ignition and Combustion of
behavior of propellants as a function of the loadingdensity,
Liquid Gun Propellants+" 22nd Int. Annual Conference of
it was found that the equilibrium burningstarted at loading
ICT, Karlsruhe, Germany, July 2 Ä… 5, 1991, pp. 49/1 Ä… 10.
(9) F. Volk, "!Utilization of Propellants for Inflator and Belt
densities higher than 10 to 20 g/l. This result is also in
Restraint Systems+", 4th International Symposium on Special
agreement with experimental results of Andrejev(12) who
Topics in Chemical Propulsion: Challenges in Propellants and
found that the equilibrium burning of nitric esters starts at
Combustion 100 Years After Nobel, Stockholm, Sweden, May
pressures higher than 1 to 1.5 MPa.
27 Ä… 31, 1996, pp. 457 Ä… 464.
(10) F. Volk, "!Analysis of Reaction Products of Propellants and
High Explosives+", 3rd Symposium on Analysis and Detection
of Explosives, July 10 Ä… 13, 1989, Mannheim-Neuostheim,
4 Conclusion
Organized by Fraunhofer-Institut f¸r Chemische Technologie
(ICT), pp. 12/1 Ä… 18.
Several explosives have been calculated thermodynami- (11) F. Volk, "!Reaction Products of Nitrocellulose and Nitramine
Containing Propellants+", 22nd Int.Pyrotechnics Seminar, Fort
cally by using the ICT-Code. It was shown that oxygen
Collins, CO, USA, 15 Ä… 19 July 1996, pp. 717 Ä… 724.
balance and enthalpy of formation are the most important
(12) K. K. Andrejew, "!Thermische Zersetzungs- und Verbren-
parameters, which influence combustion temperature, spe-
nungsvorg0 nge bei Explosivstoffen+", Erwin Barth Verlag
cific energy, heat of explosion and gas formation.
KG, Mannheim, 1964, p. 92.
Comparing the reaction products of liquid propellants
and solid propellants having the same oxygen balance, the (Received March 13, 2002; Ms 2002/008)