Note: Descriptions are shown in the official language in which they were submitted.
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PYROTECHNICAL SMOKE CHARGES N-
Technical Field
This invention relates to pyrotechnical smoke charges,
which, in the visible and in the infrared spectra, generate
substantially impervious smoke, as characterized in the
claims.
Background Art
Artificial smoke is used to keep frost away from
plantations (especially orchards and vineyards). Smoke or oil
mist is usually generated or a fine water mist is sprayed;
each is optionally stabilized by glycerin, a fatty alcohol, or
a similar substance and is spread over crops to be protected
in a more or less thick layer in order to reflect the heat
radiated from the soil and thus to prevent cooling. In
keeping with the purpose, these mists or clouds must be
maintained over longer periods of time; any loss resulting
from condensation and wind movement must be made up by
continuing new smoke generation. This is why continually
operating systems are employed in most cases for this purpose.
Artificial smoke is also used in the military sector to
camouflage military installations, troop units and vehicles.
In particular, when providing protection for troop units and
vehicles, it is important to preclude direct observation by
the enemy of those units and vehicles for a short period of
time, for which purpose a pyrotechnical charge is usually
?5 fired in the direction of the enemy; that charge is
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distributed like shot fired from a shotgun and forms a
multitude of smoke-generating particles which provide for very
fast and uniform smokescreen coverage of larger surface areas
[see DE-AS (German Patent Application published for
opposition) 30 31 369 and the literature cited therein].
A large number of=uarious smoke and mist mixtures has
become known for this purpose.. Such mixtures are based on,
e.g., titanium tetrachloride, silicon tetrachloride or
chlorosulfonic acid (or their combinations with ammoniaDr
sulfur trioxide) as liquid smoke generators or red phosphorus,
HC mixtures (hexachloroethane/zinc/zinc oxide) or ammonium _
perchlorate/zinc oxide as solid smoke generators. In an
operational situation, these substances are converted either
through a secondary combustion reaction or through suitable
products which are released together during their mixing.
Decisive factors in the quality of smoke formation are speed
of formation, concentration, and the manner of spread as well
as the duration of smoke screen coverage. Suitable smoke
mixtures are known for these purposes (see DE-AS 30 31 369).
See also, for example, DE-OS 25 56 256, DE-OS 25 09 539,
DE-OS 18 12 027, DE-AS 12 46, 488, DE-OS 30 12, 405, DE-OS 27
29 055, DE-OS 27 43 363, DE-OS -19-13 790 [DE-OS -- German
Patent Appliction published for inspection].
But these mixtures entail a critical disadvantage with
?5 respect to broad use in modern defense technology. In the
past it was particularly important to generate a smokescreen
which would be as dense as possible in visible light; however,
present-day military observers, in addition, also 'have
infrared detection, direction-finding and heat-generating
0 instruments which exploit the fact that military targets emit
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very intensive heat radiation because of'their energy output
and that radiation can be detected at great ranges. Because,
- on account of atmospheric components, such as CO2 and water
vapor, infrared radiation of certain wavelengths is absorbed
$ selectively, these instruments work preferably in the
so-called "windows" of the atmosphere which are at from 0.7 to
1.5 mp, from 2 to 2.5 mp, from 3 to 5 mp and from 8 to 12 mp.
In particular efforts are now being made to work in the 8 to
mu range because, in that range, disturbances due to smoke,
10 haze and ordinary fog are minimal. It is therefore the
purpose of pyrotechnical smoke charges, conversely, to
guarantee the highest possible absorption or reflection of IR
radiation in this range.
Moreover, most pyrotechnical smoke charges contain
corroding, toxic or highly acid components,.such as phosphorus
pentoxide, hydrochloric acid, sulfuric acid, titanium or zinc
salts, which are extraordinarily harmful to human beings and
plants in the concentration found in smoke. Due to the
addition of metal oxides, buffer substances and ammonium
compounds, steps were therefore taken in most present-day
smoke charges to make sure that the smoke generated is neutral
or only as acid as absolutely necessary. One purpose of this
invention also resides in modifying known smoke charges to
preclude or minimize their reacting in an acid manner.
Summary of the Invention
These problems are quite surprisingly solved by measures
described in the claims, that is to say, by adding an
appropriate cesium compound to known smoke charges.
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The invention has a number of related aspects, including
the use of cesium in compound form to reduce the transparency
of smoke generated by a pyrotechnic smoke charge to IR
radiation, corresponding smoke charges and their compositions
and even the resulting generated smoke. Particularly
advantageous results are obtained with charges comprising any
one or any combination of the following components:
phosphorus, zirconium/nickel alloy, boron (particularly
amorphous boron) and ammonium chloride.
Illustrative pyrotechnic smoke charges have from 0.5 to
50 percent by weight of cesium compound(s), preferably from 5
to 25 percent by weight. The cesium compound is, e.g., cesium
chloride, cesium bromide, cesium nitrate, cesium oxide or any
combination thereof. It is advantageous for the charge to be
a hexachloroethane charge with metal powder, especially
silicon and/or aluminum powder.
Such a charge has, e.g., from 50 to 70 percent by weight
of hexachloroethane, from 20 to 40 percent by weight of
silicon and/or aluminum metal powder and from 1 to 20 percent
by weight of the cesium compound(s).
The invention is particularly advantageous with
phosphorus-containing charges, especially those having at
least about 50 percent by weight of phosphorus. Other
advantageous charge components include zirconium/nickel alloys
(e.g., in an amount of from 3 to 15 percent by weight), boron --
(e.g., in an amount of from 5 to 20 percent by weight),
aluminum-powder (e.g., in an amount of from 3 to 20 percent by =
weight), red phosphorus (e.g., in an amount of from 30-to 50
percent by weight) and ammonium chloride (e.g., in an amount
of from 5 to 25 percent by weight). The charge components are
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optional, but are advantageou'sly incorporated in a pyrotechnic
smoke charge of this invention either individually or in any
combination.
The Invention
By incorporating a cesium compound in a pyrotechnic smoke
charge, quite surprisingly, transparency of the resulting
smoke to IR light, especially IR light with wavelengths of
from 3 to 5 or from 8 to 12 mp, is significantly reduced,
although it has thus far been impossible to determine what
this is based on. -
Since cesium salts in the near IR spectrum of 12 m. do
not reveal any absorption (which can be traced back to
oscillation) in which the cesium ions participate (cesium
halogenides do not reveal any oscillation, while cesium
nitrate reveals merely the oscillation of the nitrate group at
7.2 mu), the possibility of direct absorption of the IR light
is extremely remote. As the amount of cesium salt is
relatively small, corresponding to an average of 25%, compared
to the total quantity of smoke, and because, accordingly,the
other smoke-forming components are present in smaller
quantities; the=increase in the particle number of the
dispersed system cannot be responsible for this effect.
Because, according to observations so far, the settling speed and
condensability of the formed smoke clouds do not differ
from those of the corresponding smoke charges without the
addition of cesium salt, an improvement in the scatter effect
of the generated particles also does not seem to be
responsible for this effect. Assuming that Stokes' Law
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applies for these particles in a first approximation, that is
to say, assuming that the settling speed is proportional to
the square of the particle diameter, an enlargement of the
particle diameter by 1 m u in the customary smoke charges to a
figure of 10 mp -- which would be necessary for effective
scatter in the IR range of from 8 to 12 mu -- would mean an
increase in the settling speed by a factor of 100. It
therefore remains reserved for further investigations to find
a satisfactory theory as to why the pyrotechnical smoke
charges according to the invention have satisfactory density
both in the visible and in the IR spectra.
This invention furthermore is intended to increase the
smoke yield of phosphorus-containing smoke charges.
The usually employed metals, magnesium and titanium, lead
to an ash content of from 60 to 70% after the burnout of smoke
charges.
Quite surprisingly, it is possible to increase the
effectiveness of such smoke charges by using -- instead of
magnesium and titanium -- a zirconium/nickel alloy, preferably
with 70% zirconium and 30% nickel. The ash content of such
charges can thus be reduced to 5%. Additions of boron work in
the same direction and further improve IR absorption.
The effectiveness is further increased through the
addition of ammonium chloride.
A great advantage of the subject smoke charges is that
they act passively. That means that they do not reveal any
heat tone of their own and thus do not alter the image of
surroundings in IR sights.
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Examples
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In the following examples a series of smoke charges
according to the invention is compared with corresponding
smoke charges without the addition according to the invention.
Example 1.
Ammonium Perchlorate Smoke
1.7 kg of ammonium perchlorate, 1.5 kg of zinc oxide, 0.8
kg of polychloroisoprene, and 0.5 kg of ammonium chloride are
made into a dough with a solution 0.5 kg dioctylphthalate in 1
liter of methanol. This mixture is forced through a sieve
with a mesh width of from 0.3 to 0.5 mm and is dried on a
screen. The dried granulate is then pressed under a pressure
of 500 - 1500 bar according to DE-AS 30 31 369 to form blanks
of about 50 g. Each time, 20 blanks are combined with an igni-
tion charge, according to example 2 in DE-AS 30 31 369, in a
synthetic or metal casing to form one charge.
The ignition charge consists of the components magnesium
powder (1,2 kg), ferroprussiate (0,9 kg) amorphous boron
(2,39 kg), chlorparaffine powder (0,8 kg) and black powder
(4,71 kg). Magnesium powder and ferroprussiate were premixed,
chlorparaffine solved in 2 liters of perchloroethylene was-. --
added and mixed. The amorphous boron was added and mixing was
repeated for 5 minutes. Finally the black powder was filled in, _-
mexed with the other components for 10 minutes, dried and
pressed under 1500 bar.
The same mixture as above is furthermore mixed with 0.4 kg =
of cesium nitrate and is processed in the same manner into
blanks weighing about 50 g. As above, in each case 20 blanks
are assembled with an ignition charge in a casing to form a
single load.
. To judge the smoke effect, three white plates, heated to
about 40 degrees Centigrade are set up out in a field at an
interval of 10 m and are observed from a range of 100 m with
IR and optical sights with wavelengths of 10 mp, 3.5 m-p and
0.6 m V. Smoke charges with the above composition are fired
with a propellent charge at a point from about 40 to 50 m in
front of the target, where, within a matter of seconds, a 3 to
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15 m high and 25 to 40 m wide and deep smokescreen is formed.
At a temperature of 22 degrees Centigrade and a relative air
- humidity of 48%, the coverage conditions given in the
following table are then determined.
By "very good" we mean coverage of from 95 to 100%, that
is to say, the target can no longer be distinguished from the
background. By "good" we mean coverage of from 80 to 95%,
that is to say, the target just about cannot be made out. By
"moderate" we mean coverage of from 50 to 80%. By "poor" we
0 mean coverage of less than 50%, in which case the target- can
still be clearly made out.
Table 1
IR Wavelength 0.6 u 3.5 u 10 U
Perchlorate good poor poor
Perchlorate/CsNo3 very good good good
Example 2.
Hexachloroethane Smoke
2.5 kg hexachloroethane, 0.8 kg zinc oxide, 0.4 kg
silicon powder, 0.3 kg aluminum powder and 0.3 kg amorphous
0 boron are mixed intensively and are turned into a dough in a
kneader with 2 kg of a 10% elastomer-like solution- in acetone.
The mixture is processed into blanks using the same method as
in Example 1 and the blanks are insulated by means of an --~
additional coating of inethacrylic resin and are combined to
5 form smoke charges according to Example 1.
The same mixture as above, but with the addition of'l kg
of cesium nitrate, is processed into smoke charges in the
corresponding manner.
The elastomer consisted of butadiene. Polybutadiene is usable as
well.
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`-- The smoke effect is determined according to Example 1
whereby the results given in the following Table 2 are
obtained. The smoke formed has a pH value of from about 5
to 7.
Table 2
IR Wavelength 0.6u 3.5u l0u
HC-mixture very good moderate moderate
HC/CsCl very good very good very good
Example 3.
Red Phosphorus Smoke
0.65 kg of red phosphorus, 0.15 kg of iron (III)
oxide, 0.15 kg of aluminum powder, and 0.15 kg of magnesium
powder are kneaded with 0.2 kg of 10% elastomer bonding
agent and are processed into blanks according to Example 1.
Mixtures, which in addition contain 0.40 kg of cesium
nitrate, are processed into blanks in the same manner.
The smoke effect is determined according to Example
1. The results obtained are shown in Table 3, below.
Table 3
IR Wavelength 0.6u 3.5u l0u
Phosphorus very good poor poor
Phosphorus/CsN03 very good very good very good
Phosphorus/RbN03 very good very good good
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Example 4.
= 0.65 kg of hexachloroethane, 0.2 kg of silicon powder,
and 0.15 kg of aluminum powder are mixed and, under light
pressure, are pressed in a casing which is connected with a
propellent and ignition charge.
Mixtures which, in addition, contain 0.01-0.10 kg cesium
chloride are processed in the same manner.
The following smoke effects are obtained:
Table 4
,0 IR Wavelength 0.6 u 3.5p 1011
HC-smoke good moderate moderate
HC-CsCl very good very good very good.
Proven prescriptions are given in the following examples.
Compounding and other procedures are as set forth in the
=5 preceding examples.
Butadiene (polybutadiene) is used as bonding agent.
Example S. 55% red phosphorus
23% cesium nitrate
0 12% zirconium/nickel alloy, 70:30 - -~
10% butadiene
Example 6. 55% red phosphorus
20% cesium nitrate
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'= ~ 4% manganese powder =
6% zirconium/nickel alloy, 70:30
= 5% fine aluminum powder
10% butadiene
Example 7.
27% NH4C1O4
8% Zr/Ni 70:30
5% fine aluminum powder
25% CsN03
24% NH4C1
10% butadiene
Example B.
43.75% red phosphorus
33.00$ CsN03
6.00% amorphous boron
4.75% titanium powder, smaller than 100 m u
12.50$ polybutadiene
Example 9.
43.75% red phosphorus
33.00$ CsN03
6.00% amorphous boron
4.75% zirconium/nickel alloy, 70:30 - ~
12.50% macroplast B 202. (Butadiene in a solvent produced by
Henkel, Dusseldorf, Germany)
The invention and its advantages are readily understood
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from the foregoing description. Procedures, techniques,
ingredients and details other than those specifically called
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. for are conventional and well within the skill of the art.
,., Various changes may be made in the processes, formulations and
= products without departing from the spirit and scope of the
invention or sacrificing its material advantages. Examples
provided herein are merely illustrative of preferred
embodiments.
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