Green pyrotechnics
Doru Adrian GOGA
Military Technical Academy - Bucharest
1.1 Introduction
Explosive materials such as high explosives, propellants and pyrotechnics are used in
weapon systems to perform a variety of functions. They provide the energy required to
deliver the payload to the target and to obtain the desired terminal effect. Because of their
high energy content, these materials are sensitive and can be initiated by stimuli such as
heat, shock, friction, impact, and electrostatic discharge. All of these stimuli may be
encountered in development programs, and later in the manufacture, transport, storage, and
operational or training use of explosive materials.
The careful and judicious selection of explosives is important since it will affect the
sensitivity and safety of munitions and the vulnerability of weapon platforms. Trade-off with
performance can be made, but in general, the more powerful the explosive used, the more
sensitive it is to stimuli, and the more protection must be provided to shield munitions in
hazardous areas. Since in many applications space is limited, it is often impossible or
unfeasible to provide the increased protection. Therefore, in qualifying explosives, National
Authorities must exercise caution and concern for the sensitivity and the suitability for service
of the explosive materials being considered for all military applications. Further, munition
designers should select the least sensitive explosive material that meets the operational
requirements defined for their application.
An explosive material is a substance (or a mixture of substances) capable by chemical
reaction of producing gas at such temperature and pressure as to cause damage to the
surroundings. Included are pyrotechnic substances even though they may not evolve gases
as they react. This document refers only to those explosive materials whose application
requires that they react reliably on demand. The term "explosive" thus includes all solid and
liquid materials variously known as high explosives and propellants, together with igniter,
primer, initiatory and pyrotechnic (e.g., illuminant, smoke, delay, decoy, flare, and incendiary)
compositions.
Pyrotechnic compositions are substances (or a mixture of substances) that when
ignited, undergo an energetic chemical reaction at a controlled rate intended to produce on
demand and in various combinations, specific time delays or quantities of heat, noise, smoke,
light or infrared (IR) radiation. Pyrotechnic compositions may be used to initiate burning
reactions such as in igniters.
This work will approach a multitude of pyrotechnical subjects. The word “Pyrotechnics”
comes from the Greek words pyro meaning "fire" and tekhnikos "made by art".
Often, there is some confusion between “pyrotechnics” and “explosives science” or
“detonics”. This can be explained by the explosives classification for their intended roles, as
represented in figure 1.
EXPLOSIVE MATERIALS
An explosive material is a
substance (or a mixture of
substances) capable by chemical
reaction of producing gas at such
temperature and pressure as to
cause damage to the surroundings
Primary explosives
A substance or mixture of
substances used to initiate a
detonation or a burning reaction. In
their intended role these materials
are sensitive to a range of thermal,
mechanical and electrical stimuli
Booster explosives
An explosive material used to augment
and transmit the reaction (initiated by
the primary explosive) with sufficient
energy to initiate a detonation reaction
in the main charge high explosive
High explosive
A material that is used as a detonating
final charge
Pyrotechnic Compositions
These are substances (or a mixture of substances)
that when ignited, undergo an energetic chemical
reaction at a controlled rate intended to produce on
demand and in various combinations, specific time
delays or quantities of heat, noise, smoke, light or
infrared (IR) radiation. Pyrotechnic compositions
may be used to initiate burning reactions such as in
igniters
Gun powders and propellants
This is a substance (or a mixture of substances)
that is required to burn in a controlled manner
within a gun combustion chamber producing hot
gases capable of propelling a projectile at high
velocity. Combustible cases may also be
included as they contribute to the overall energy
of the propellant
Figure 1 Explosive classification
Pyrotechnics is the technique, the science and the art to create, to maintain and to
manage the “FIRE”. The study, the design or the development of pyrotechnic compositions
impose anywhere and all the time, theoretical and experimental tests.
Today, Pyrotechnics is a frontier multidiscipline science regarding:
 Study of pyrotechnic compositions combustion phenomena;
 Study of physical, chemical, energetic, sensibility, stability properties of pyrotechnic
compositions;
 Manufacture and preparation methods of pyrotechnic compositions and their loading
process into the pyrotechnic systems;
 Special pyrotechnic effect study (illumination, signaling, smoke Vis and IR screening,
colored smoke, tracer) and the interactions with the environment (air, water, earth,
people).
Pyrotechnic compositions / systems classification
A pyrotechnic system is an ensemble of pyrotechnic compositions or pyrotechnic layers,
structures, mechanical components, pieces or accessories used to integrate or accomplish
specific operational missions. We can considere a pyrotechnic chain similar to multilayer
pyrotechnic compositions, and this can be considered a part of a pyrotechnic system.
Depending on their intended role, pyrotechnic compositions/systems can be divided as:

Illumination flare (cartridges, projectiles, mortar bombs, rocket hand fired,
ground illuminating flare etc.), are used for signaling, illumination, able to light by night
in order to facilitate the different objectives; Illuminating pyrotechnic systems may be
dropped from aircraft, fired from rocket or artillery, or deployed by flare guns or
handheld percussive tubes.

Flash-bang (grenades, charges) used to emit an intensely loud „bang” and a
blinding flash, sufficient to cause immediate flash blindness, deafness and inner ear
disturbances. Exposed personnel experience disorientation, confusion and loss of
coordination and balance.

Tracers (devices, bullets, projectiles) are used to make visible the projectiles
trajectories by day or by night. This enables the shooter to make aiming corrections
without observing the impact of the rounds fired and without using the sights of the
weapon.

Signaling (Handheld cartridges, star clusters, star parachutes, smoke
parachutes, surface trip flares, etc.) uses to signal by day or by night at distance;
Pyrotechnic signals are used in difficult situations, when normal communication means
like radio, telephone are not effective in certain tactical situations. Pyrotechnic signals
are prescribed at command level.

incendiary (bullets, bombs, projectiles etc.) designed to catch fire, to burn some
objectives inflammable or not;

Smoke screening (generators, grenades, proiectiles, mortar bombs etc.) The
generation of a thick and dense cloud is used to conceal movement of vehicles and
troupes, to camouflage, to induce deception, to adopt a defensive or offensive strategy.

Infrared decoy flare (flare cartridge, flare dispenser) is an aerial countermeasure
used by a plane or helicopter to counter a heat-seaking / infrared homing missile; the
radiation emitted by the flare has the goal to make infrared-guided missile seek out the
heat signature from the flare rather than the aircraft's engines.

Training and simulators (booby trap simulator, ground burst simulator, hand
grenade simulator, explosive simulator etc.), are used during training and military
exercises. They simulate simulates hand grenades, booby traps, land mines, and rifle
or artillery fire; in combat they can realize the diversion and confusion to enemy;

Prime ignition sources (matches, stab, percussion and electric primers etc.)
used to facilitate the ignition of pyrotechnic devices by friction, impact, temperature,
flame or other stimulus;

Delay (fuse, delay device) is a pyrotechnic composition filled in some devices
used provide a specific time between activation and production of the main effect;

Heat generating compositions for thermal batteries used sources to provide ionic
conduction in a molten electrolyte and to maintain the working temperature of the
battery during the discharge of the electrochemical elements.

Base bleed (devices attached to great caliber projectiles), used to generate
gases and reduce the drag coefficient and to increase the maximum range;

Gas generators (generators), used to generate a large quantities of gas, to
power turbo-pumps in rocket motors, to deploy airbags;

Other applications.
Combustion or deflagration of pyrotechnic composition are complex oxidizing / reduction
process, where the oxidation of some components called carburants is produced
simultaneously with the reduction of other components called oxidants.
The pyrotechnic compositions are mechanical mixtures of two or more components
which are solids most of the time. The degree of homogeneity of these compositions, the
nature of components and the proportion of components will determine their properties.
The combustion process is carried out in so called “the reaction space” where the heat
transfer is done little by little, from reaction products to inactivated composition. In order to
get the specific reaction conditions, is required a local increase of temperature which is
realized by using some special compositions (first fire).
1.2 General conditions required for the pyrotechnic compositions/systems
Combustion compositions and the functioning of the pyrotechnic systems is the base of
generating special pyrotechnic effects: illuminations, signaling, smoke, incendiary, catch fire,
simulation and training etc.
In order to safely store, transport, handle and operate the pyrotechnic systems/
compositions, some requirements must be aquired for pyrotechnic compositions as:
 Chemical and physical stability;
 Sensitivity to different stimuli;
 Performance characteristics;
 Low toxicity or friendly impact on the environment.
The main technical conditions required for the pyrotechnic compositions/systems are:
- Maximum pyrotechnic effect per mass unit composition;
- The combustion has to uniformly develop at a constant rate, according to all the
environmental conditions (pressure and temperature);
- A good physical-chemical stability for the whole life time;
- Appropriate sensitivity and reduced explosive reaction to the mechanic, thermal and
electric agressions;
- Non violent explosive properties (explosivness) and the lowest risk of a mishap;
- The absence of toxical reaction products for the human body and the environment;
- Easy, efficient and economical manufacturing.
It’s not always easy to design and obtain a composition or pyrotechnic system which
would meet all these requirements. More often, other requirements are added to the
mandatory ones, some of them of tactical nature, which can’t be quantified into a technical
language. It’s the pyrotechnician’s job to implement the specific requirements and to find
practical ways to insure that all the required conditions are followed.
Despite all the difficulties, including the intuitive ones, we can get the desired results
through a better understanding of the raw materials, production processes, testing and
assessment methods.
There are two different situations, in reference to the requirements analysis of a
pyrotechnic composition/system:
1. Knowing the system/composition and is required the verification of its specification;
2. Designing and manufacturing of a new composition/system – it’s starting from
general, tactical and performance requirements.
1.3 General notions about pyrotechnic compositions/systems manufacturing
The pyrotechnic compositions are homogenous mixtures of multiple components. It is
relatively easy to mix a few solid substances. Nevertheless, to insure the mixture
homogeneity or for getting the ideal progress conditions reaction it’s mandatory to follow
successive steps, when the elements of the pyrotechnicl composition suffers changes or
modifications.
The degree of homogeneity or the mixture uniformity is affecting the chemical
composition of the pyrotechnical mixture, with several implications over the performance
characteristics, stability and sensitivity of the pyrotechnic system.
Thereby, in order to prepare and charge a pyrotechnic composition the following steps
are necessary:
1. Components preparation;
2. Pyrotechnic composition preparation (mixing, granulation, draying);
3. Completing the composition preparation (draying, granulometric sorting out);
4. Pyrotechnic composition charging (by pressing compressing or other methods).
The manufacture and loading process of a pyrotechnic composition have to be easy and
applicable to a mass production.
Technological process of pyrotechnic
composition manufacturing
Raw materials acceptance
Components
preparation
Pyrotechnic composition
preparation
Mixing the
components
Pyrotechnic
Composition
Loading
Pyrotechnic
System
Acceptance
Finishing up the
composition
Figura 1.1 The diagram for a pyrotechnic composition manufacture process
2. CHEMICAL COMPONENTS AND DESIGN PRINCIPLES
Pyrotechnic compositions are mechanical mixed compositions of two or more components which are in direct contact, and are capable to
react and release a large quantity of energy and reaction products, able to generate a “pyrotechnic effect".
There are so many chemical formulations for pyrotechnic compositions. Any attempts to
classify or to simplify are always subjective. But, we can state that a pyrotechnic composition
may contain the following components:
 Oxidants;
 Carburant / Fuels;
 Binders;
 Other components.
Oxidants have the role to generate the oxygen or another similar element (Cl, F) that are
necessary for the combustion reaction. In some pyrotechnic compositions, the oxygen isn’t
necessary because the air contains oxygen. This is the exception for some incendiary
formulations.
Carburant (often named fuel) is the indispensible component for a pyrotechnic
composition. The heat released during the combustion process and the chemical composition
of the reaction products determines the “pyrotechnic effect”.
In order to ensure the homogeneity but also the geometrical configuration of a
pyrotechnic charge it is necessary to introduce the binders.
Every specific pyrotechnic device has a destination: illuminating, tracing, incendiary,
signaling, decoy, screening etc. It is necessary in some situation to increase or decrease the
combustion rate or the sensibility to external stimuli. Therefore others components are
necessary for pyrotechnic compositions:






Moderators / accelerators of combustion reaction;
Sensitizer / Inhibitors;
Stabilizers;
Flames coloring components;
Smoke components;
Technological components.
2.1 Oxidants
Every pyrotechnic composition must contain an oxidant and a carburant / fuel.
The most used oxidants are: KNO3, KClO3, Sr(NO)3 etc. In some cases chlorine or
fluorine components are also used: CCl4, C2Cl6, C6Cl6, NaFl.
As an example the combustion reaction for a smoke composition can be written as
following:
CCl4  2 Zn  C  2 Zn Cl2
In this case carbon tetrachloride is the “oxidant” (comburant in french).
The selection of the oxidant (s) for a specific pyrotechnic composition is very important.
The oxidant determines the chemical stability, sensibility, performance and other
characteristics for the mixture.
It can’t be ignored that a specific role for a pyrotechnic composition means a specific
chemical composition for the reaction products.
As an example in order to get a red flame it is necessary to obtain in addition to the
reaction products SrO / SrCl as well. In this case it’s a must to use an oxidant which
contains Sr, so we will use SrCO3 / Sr(NO)3.
It is also important to know that the oxidant determines the reaction rate and other physical,
chemical and thermodynamical properties..
In pyrotechnic compositions the oxidant can be:
- Salts;
a. nitrates: Ba(NO3)2, Sr(NO3)2, KNO3, NaNO3;
b. chlorates: KClO3, Ba(ClO3)2;
c. perchlorates: KClO4 , NH4ClO4 ;
- Peroxides: BaO2 , PbO2;
- Oxides;
a. iron oxides: Fe3O4, Fe2O3;
b. manganese oxides: MnO2;
c. lead oxides: Pb3O4.
The following oxidants can also be used: Na2SO4, CaSO4, BaSO4, BaCrO4, PbCrO4,
K2Cr2O7, NaClO4, NH4NO3, PbO2, SrO2, SiO2, CuO etc.
Physical, chemical, and other properties for the most used oxidants are presented in table
1.
Where:
TT - melting temperature;
TF - boiling temperature;
QF - oxidant heat of formation;
QP - heat of formation of reaction decomposition products;
QR – heat of decomposition reaction;
MOX/100 – oxygen mass (g) released by 100 g oxidant decomposition;
MOX - oxidant mass (g) which releases 1 g oxygen.
Table 2.2 Oxidants properties

M
g/mol
261.38
85.00
101.10
80.05
TT
0
g/cm  [ C]
1.
2.
3.
4.
Chemical
formulation
Ba(NO3)2
NaNO3
KNO3
NH4NO3
3.240
2.265
2.109
1.725
592
308
336
169
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
Sr(NO3)2
Ca(NO3)2
Pb(NO3)2
NaNO2
KClO3
NH4ClO4
KClO4
Sr(ClO3)2
Ba(ClO3)2
KMnO4
Na2CrO4
K2CrO4
Na2Cr2O7
K2Cr2O7
PbO2
MnO2
211.65
164.10
331.23
69.01
122.55
117.50
138.55
254.54
304.27
158.03
162.00
194.20
267.85
294.21
239.21
86.93
2.9
4.530
2.30
1.950
2.520
3.18
9.07
5.0
645
21. BaO2
169.36
4.20
-
22. Fe3O4
232
5.2
1527
No.
3
370
610*
414
530
Decomposition reaction
Ba(NO3)2  BaO  N2  2.5O2
2NaNO3  Na2O  N2  2.5O2
2KNO3  K2O  N2  2.5O2
2NH4NO3  4H2O  2N2  O2
NH4NO3  2H2  N2  1.5O2
Sr(NO3)2  SrO  N2  2.5O2
Ca(NO3)2  CaO  N2  2.5O2
Pb(NO3)2  PbO  N2  2.5O2
2NaNO2  Na2O  N2  1.5O2
KClO3
 KCl  1.5O2
4NH4ClO46H2O4HCl2N25O2
KClO4
 KCl  2 O2
Sr(ClO3)2  SrCl2  3 O2
Ba(ClO3)2  BaCl2  3 O2
2KMnO4  K2O  2MnO  2.5O2
2 Na2CrO4 2Na2O  Cr2O3 1.5O2
2 K2CrO4  2K2O  Cr2O3  1.5O2
Na2Cr2O7  Na2O  Cr2O3  1.5O2
K2Cr2O7  K2O  Cr2O3  1.5O2
PbO2
 PbO  0.5O2
MnO2
 MnO  0.5 O2
MnO2
 Mn  O2
BaO2
 BaO  0.5 O2
BaO2
 Ba  O2
Fe3O4 3Fe + 2O2
QR
kcal/g
-0.4
-0.7
-0.75
0.32
-1.1
-0.42
-1.44
-0.1
-0.8
-0.14
QP
kcal/g
133
101
87
57
142
93
133
0
MOX/100
g
30
47
40
20
60
38
49
24
35
39
34
46
38
32
25
14.8
12.3
17.9
16.3
6.7
18
37
9
18
28
Qf
MOX
g
kcal/mol kcal/kg
3.27
234.60
897.9
2.13
110.56
1300.7
2.53
116.93
1156.6
5.0
84.75
1059.0
1.67
2.65
230.90
1090.9
2.05
221.70
1351.0
4.14
104.57
315.7
2.87
87.40
1266.5
2.55
92.00
750.7
2.94
67.30
572.8
2.16
103.00
743.4
2.65
169.00
664.0
3.17
174.30
572.8
3.95
191.7
1213.1
6.75
307.00
1895.0
8.09
318.60
1640.6
5.58
469.00
1750.0
6.12
481.00
1635.0
14.9
64.40
269.0
5.44
122.40
1408.0
2.72
10.59 148.40
876.2
5.3
3.34
88.66
726.1
Hf
kcal/mol kcal/kg
236.90
906.3
111.72
1314.1
118.09
1168.0
87.36
1091.3
233.20
222.04
106.89
88.20
93.20
70.2
104.5
171.00
176.60
192.90
308.00
319.80
471.00
483.00
65.00
123.00
1101.8
1353.1
322.7
1278.7
760.5
597.4
754.2
671.8
580.4
1220.6
1901.2
1647.2
1758.4
1641.7
271.7
1414.9
149.00
879.8
93.65
767.0
2.2 Fuels
The fuel is an indispensable component to a pyrotechnic composition. It’s impossible to
have combustion without a fuel. Moreover, the desired pyrotechnic effect imposes the
nature of reaction products, the amount of reaction heat, the combustion temperature,
or the combustion rate.
2.2.1 How to select a fuel component
When we make the choice for fuel compound we must consider all the requirements
imposed for the component to achieve the pyrotechnic effect.
For illuminating compositions or signaling, optimal effect is achieved to a higher
combustion temperature. So it is important to use only a high caloric compound.
For colored signaling smokes a high combustion temperature is not allowed because
it can destroy the colorants.
When we select the carburant it is important to know the oxidation reaction products
and their properties.
Figure 2. CuCl Emission spectrum
The fuels used in pyrotechnic compositions must satisfy the following requirements:
 To release a sufficient thermical effect;
 To be easily oxidized;
 To release the specific oxidation products;
 To be chemically and physically stable between –50 0C  60 0C;
 To be non hygroscopic;
 To be easily processed / grinded;
 To be non toxic;
 To be available.
There are different types of carburants:
A. Inorganic fuels:
a) metals: magnesium (Mg), aluminum (Al), zinc (Zn) etc.;
b) metallic alloys: aluminum-magnesium (AM), silicium – aluminum etc.;
c) metalloid: phosphorus (P), sulfur (S), carbon (C);
d) sulfides: phosphorus trisulphide (P4S3), antimony sulfide (Sb2S3);
e) other substances: calcium silicide (CaSi2).
B. Organic fuels
a)
hydrocarbons from aliphatic series: gasoline, kerosene, benzene, oil;
b)
carbohydrates: starch, lactose, sucrose, cellulose;
c)
other organic substances.
Table 2 Fuels, oxides and heat of formation
Combustible
A
Symbol
[g]
Be
Al
B
Li
H
Mg
Ca
Si
Ti
V
P
C
Zr
Na
K
Sr
Ba
Zn
Ce
Hf
Th
As
Sb
S
Se
Cr
Mn
Fe
9.0
27.0
10.8
6.9
1.0
24.3
40.1
28.1
47.9
51.0
31.0
12.0
91.2
23.0
39.1
87.6
137.4
65.4
140.1
178.6
232.1
74.9
121.8
32.1
79.0
52.0
54.9
55.8
Oxides
Formulas
BeO
Al2O3
B2O3
Li2O
H2O
MgO
CaO
SiO2
TiO2
V2O5
P2O5
CO2
ZrO2
Na2O
K2O
SrO
BaO
ZnO
CeO2
HfO2
ThO2
As2O5
Sb2O5
SO2
SeO2
Cr2O3
MnO
Fe2O3
Heat of formation [kcal/mole]
M
[g/mol]
25
102
70
30
18
40
56
60
80
182
142
44
123
62
94
104
153
81
172
211
264
230
324
64
111
152
71
160
Qf OXIDE
138
393
302
142
68
146
152
208
218
437
360
94
258
99
85
141
133
83
233
271
293
219
230
71
56
273
93
195
Q1= Qf/mA
15.3
7.3
14.0
10.3
34.2
6.0
3.8
7.4
4.6
4.3
5.8
7.8
2.8
2.2
1.1
1.6
1.0
1.3
1.7
1.5
1.3
1.5
0.9
2.2
0.7
2.6
1.7
1.7
Q2= Qf/M
5.5
3.9
4.3
4.7
3.8
3.6
2.7
3.5
2.7
2.4
2.5
2.1
2.1
1.6
0.9
1.4
0.8
1.0
1.4
1.3
1.1
1.0
0.7
1.1
0.5
1.8
1.3
1.2
Q3= Qf/n
69
79
60
47
23
73
76
69
73
62
51
31
86
33
29
70
66
41
78
90
98
31
33
24
19
55
46
39
3 Green pyrotechnic compositions and their applications
The use of pyrotechnics extends well beyond fireworks, with common applications
in airbags, road flares, and fire extinguishers. Perhaps the most common use of
pyrotechnics, though possibly overlooked by the general public, is by the militaries of the
world. Military pyrotechnics encompasses many areas, including, but not limited to,
illuminating charges, smokes for obscuration and signaling, delay fuzes, incendiary
devices, countermeasure flares, and primers.
On the battlefield and on training ranges, the area of pyrotechnics surrounds the
warfighter, and in many cases, the proper and consistent functioning of a pyrotechnic can
be the difference between life and death
Historically, when the toxicity of chemicals was not known and when regulations
were relatively few in number, many pyrotechnic formulations were designed primarily to
function reliably. Many of these historic formulations in the aforementioned areas are still
being used today because they have already been proven-out, consistently pass quality
control tests, and function very well in a wide range of temperatures.
Today, however, more is known concerning the toxicity profile of chemicals found in
these historic pyrotechnic formulations. Some chemicals found in these pyrotechnic
formulations are no longer viewed as being acceptable due to their environmental and
occupational health hazards alike.
As the toxicity profiles of pyrotechnic chemicals have become known, governments
at the federal and state levels in the United States have called for increased regulations of
these chemicals to address environmental issues and human health concerns. Due to the
increased regulations and supposed toxicities of many traditional pyrotechnic chemicals,
the abilities of military personnel to train on training ranges within or outside the continental
United States has been hampered or prohibited. Because commercial fireworks
companies in the United States are also coming under increasing scrutiny to “green” their
fireworks, any technological breakthroughs made to generate environmentally sustainable
pyrotechnics without compromising human health may also spur interest from the
commercial fireworks sectors.
Although there is a significant interest in the development of “green”
technologies for military and civilian pyrotechnics, these technologies will be of
limited or no value if the performances and safeties of these new pyrotechnic
formulations are compromised.
Therefore,
“green”
pyrotechnic
formulations
should
consist
of
environmentally acceptable ingredients, have equal or enhanced performances, and
have identical or reduced sensitivities to ignition stimuli (i.e., impact, friction, and
electrostatic discharge) compared to the environmentally questionable pyrotechnic
munitions that are in existence today.