RU2353606C1 - Pyrrotechnical composition for creating smoke screen - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to pyrotechnics. Pyrotechnical composition for generating white color smoke while burning contains potassium perchlorate, hexachlor ethane, aluminium powder with specific surface 0.3-0.38 m²/g, zinc oxide or zinc white, technological additives - chlorinated polychloroprene rubber, plasticised with dibutyl sebacinate, and aerosyl.

EFFECT: increasing temperature and speed of composition burning, as well as covering ability of generated smoke.

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Description

The invention relates to means for the formation of smoke screens, and more particularly to pyrotechnic compositions, during the combustion of which an aerosol is generated, forming a smoke screen in air, which is used for setting evading false targets that protect equipment in combat conditions.

The level of this technical field is characterized by pyrotechnic metal chloride mixtures described in DE patent No. 1542020, class. 78d and US patent No. 3485171, nat. class 102-56, including a chlorine-containing oxidizing agent, metallic fuel and a functional smoke-generating component - zinc oxide, respectively (wt.%):

hexachloroethane 40-60; 45.5 zinc 20-30; - aluminum 1-10; 7 zinc oxide 2-10; 47.5

These compositions are not technologically advanced due to dust during manufacturing and processing, which is explosive, and are characterized by unstable combustion due to overcharging of charges by pressing.

The noted drawback is eliminated in the composition for the formation of a smoke masking curtain according to the patent FR No. 2560371, F41H 3/00, 1982, which, according to the technical nature and the number of matching features, is selected as the closest analogue to the proposed composition.

This more advanced composition includes an active oxidizing agent (potassium perchlorate), which chemically interacts with zinc oxide and metallic fuel, increasing the combustion temperature and completeness of combustion of the functional composition, which increases smoke formation and also includes binders that improve the technological properties of the mixture in the industrial manufacture of charges.

The known composition contains the listed components in the following ratio (wt.%):

potassium perchlorate 16 hexachloroztan 31 zinc 31 zinc oxide 12 neoprene binder 10

A disadvantage of the known composition, characterized by high manufacturability and the efficiency of smoke generation, is the limited use only in sealed devices due to the hygroscopicity of zinc, inactive metal fuel.

In addition, the combustion temperature of the composition is insufficient for the complete combustion of soot, which determines the gray color of the non-contrast smoke due to the small amount of potassium perchlorate.

The problem to which the present invention is directed, is to increase the temperature and burning rate of the composition, as well as the opacity of the generated smoke.

The required technical result is achieved by the fact that in the known pyrotechnic composition for the formation of a smoke masking curtain containing potassium perchlorate, hexachloroethane, metal fuel, zinc oxide and processing aids according to the invention, it contains zinc oxide or zinc white, it contains aluminum as a metal fuel powder with a specific surface area of 0.13-0.38 m ² / g, and as technological additives, chlornaairite, plasticized with dibutyl sebacinate, and aerosil, in the following ratio Ponents (wt.%):

potassium perchlorate 16-24 hexachloroethane 18-22 aluminum powder 23-27 zinc oxide 25-29 chlornairite 3-6 dibutyl sebacinate 1-3 aerosil 1-2

Distinctive features provided an increase in the manufacturability of the composition in industrial processing, as well as an improvement in the main destination indicators — an increase in the masking ability of more contrasting white smoke, which is characterized by an additional quality for the reflection of laser radiation at a wavelength of 1.06 μm, which expands the functionality when used for masking from means of detection and guidance to the protected target.

The optimal mass ratio of the components of the composition was calculated according to the mathematical model of the experimental design for the maximum smoke generation efficiency, the dispersed phase of which in the air forms an aerosol, the best masking ability of which is achieved with particle sizes close to the wavelengths of the visible spectrum.

The presence of smoke in air decreases its light transmission due to absorption or scattering of a significant part of the light by aerosol particles.

The use of finely dispersed aluminum powder with a large specific surface makes it possible to distribute it more evenly in a thermal metal chloride mixture for volume contact with an oxidizing agent, which increases the surface and the burning rate, the completeness of combustion of the composition, resulting in bright white smoke.

A relative increase in the mass content of aluminum powder in the pyrotechnic composition increases its combustion temperature, at which soot particles completely burn out, which contributes to the production of contrasting white smoke.

The content of aluminum in the pyrotechnic smoke-forming composition of less than 23 wt.% Does not provide a functional level of the combustion temperature for complete combustion of the composition.

An aluminum content of more than 27 wt.% Causes the formation of aluminum chlorides, which create a gray color of the smoke cloud, reducing masking ability.

When using aluminum powder with a specific surface of more than 0.38 m ² / g, it is difficult to disperse it due to sticking of powder particles.

When using aluminum powder with a specific surface area of less than 0.13 m ² / g mixed with an oxidizing agent, there is insufficient contact for active interaction, which reduces the combustion temperature and smoke contrast.

Potassium perchlorate serves as a smoke generator, in the composition it is used as an active oxidizer of metallic fuel, which increases the temperature of combustion and for burning soot.

When the content of potassium perchlorate in the composition is less than 16 wt.%, The specified level of the combustion temperature of the mixture is not ensured and the masking properties of the generated aerosol are reduced.

When the content of potassium perchlorate in the composition is more than 24 wt.%, The mixture burns with flame, which leads to smoke burnout and a decrease in functional efficiency.

Hexachloroztan is the main oxidizer of metallic fuel, the content of which in the thermal composition is quantitatively optimized for complete combustion of aluminum powder and aerosol generation.

When the content of hexachloroethane in the pyrotechnic composition is less than 18 wt.%, Its burning rate decreases and soot does not completely burn out, which reduces the contrast of the smoke.

The content of hexachloroethane in the composition of more than 22 wt.% Will lead to an excess of hydrocarbon radicals, that is, an increase in soot in the combustion products, which will color the smoke gray. This decreases the brightness of the smoke cloud and its contrast.

The functional smoke-generating component - zinc oxide or zinc white - is used to color the smoke in a bright white color.

The content of zinc oxide in the composition of less than 25 wt.% Reduces the saturation of the smoke cloud, the masking ability of which decreases.

The content of zinc oxide in the composition of more than 29 wt.% Is ballast, leads to a decrease in the burning rate of the pyrotechnic composition and a decrease in the efficiency of smoke formation.

The use of industrially produced zinc oxide as an alternative to the smoke-forming component based on zinc oxide reduces the consumer cost of charges, while the impurities contained in them do not significantly affect the functioning of the composition and the masking ability of the generated aerosol.

The technological additive, which additionally serves as an active oxidizing agent - chlornairite, plasticized with liquid dibutylsebacinate - increases the density and strength of the pyrotechnic charge formed without dusting and increases the masking ability of the aerosol generated during its combustion, being an additional oxidizing agent and organic fuel in the composition.

Dibutylsebacinate also serves as a regulator of the burning rate of the mixture.

When the content of chlornairite is less than 3 wt.%, The composition remains dusty, and the charge formed from it has low strength characteristics.

When the content of chlornairite in the composition is more than 6 wt.%, The burning rate is reduced, which is the reason for the appearance of a gray tint in the smoke cloud, which has a lower light-absorbing ability.

The content in the technological additive of liquid plasticizer of less than 1 wt.% Does not significantly improve the technological properties of the mixture as a whole and does not provide strength properties to the pressed charge. The masking ability (smoke density) in this case is reduced due to a decrease in the absolute amount of chlorine.

With the introduction of dibutyl sebacinate, more than 3 wt.% Leads to clumping of the mixture, reduces the combustion temperature and increases the soot removal into the masking cloud, and an excess of liquid plasticizer is squeezed onto the surface (exudated) of the charge formed by pressing.

The introduction of Aerosil is aimed at improving manufacturability by ensuring the flowability of the mixture, which can be dosed.

Therefore, each essential feature is necessary, and their combination is sufficient to achieve a novelty of quality that is not inherent in the signs of disunity, that is, the technical goal set in the invention is achieved not by the sum of the effects, but by a new effect of the sum of the features.

The proposed smoke-forming composition is prepared by mixing the components, which are introduced in the above optimal weight ratio, in a mixer type SND-100 in the following sequence.

Aluminum spherical powder of grades ASD-1 (specific surface 0.13-0.15 m ² / g) and ASD-4 (specific surface 0.34-0.38 m ² / g) according to TU 48-5-226 liquid plasticizer dibutylsebacinate, GOST 8728 for 10 minutes.

Then zinc whitewash grades BTsO, BTs-1 or BTsO-M according to GOST 202, potassium perchlorate, TU-02-627, industrial hexachloroethane, GOST 9991 and aerosil grades A-300, A-380, GOST 14922, which are mix together for 10 minutes.

The composition is ready for compression into charges, during which the plasticization of chlornairite and the composition as a whole occurs.

The table below shows typical examples from among the experimental compositions that were tested during the development and optimization of various qualitative and quantitative smoke-forming compositions of the present invention.

Table 1 shows the compositions with the content of the components within the optimized ranges of their quantitative content, with the maximum content and beyond.

Table 1 Name of components The content of the component in the composition, wt.% one 2 3 four 5 Potassium perchlorate fifteen 16 twenty 24 25 Hexachlorztan 17 22 twenty eighteen 23 Aluminum powder 28 27 25 23 22 Zinc White (Zinc Oxide) thirty 29th 27 25 23 Chlornairite 7 3 5 6 2 Dibutylsebacinate 0.5 one 2 2 four Aerosil 2.5 2 one one one

During combustion of the prepared compositions, gaseous substances and solid particles are formed as a result of reactions: KCl, ZnCl ₂ , AlCl ₃ , ZnO, Al ₂ O ₃ , СО ₂ , Н ₂ О, СО, SiO ₂ , which provide almost complete removal of slags and obtaining sufficient a dense white cloud of a masking curtain with specified characteristics in terms of brightness contrast and laser reflection coefficient.

Table 2 shows the comparative technical characteristics of the compositions No. 1-5 of table 1, DE - analogue, FR - prototype.

table 2 values Characteristics one 2 3 four 5 DE FR Burning rate, mm / s 0.8 1.8 1.9 1,6 0.8 0.5 0.25 Smoke generating ability,% 80 96 98 96 80 80 70 Masking ability, m ² / g 3.0 3.9 4,5 5,0 3.2 3.6-4.2 4.0 The content of slag,% 16 four 2 four twenty twenty thirty Checkers operating time, s 180 90 110 120 130 200 400 Brightness contrast For 13 s 0.4 0.8 0.8 0.8 0.3 0.4 0.2 For 33 s 0.2 0.7 0.7 0.7 0.2 0.2 0.1 Coefficient of laser reflection at the bottom of the wave 1.06 μm 0.13 0.28 0.32 0.30 0.12 0.15 0.10 Smoke color * FROM B B B FROM s / c FROM * C - gray, B - white, s / c - grayish.

From table 2 it can be seen that for all destination indicators, the proposed pyrotechnic compositions 2-4, the components of which are contained in the declared ranges of their mass ratio, significantly exceed the corresponding parameters of smoke-forming compositions by analogue and prototype.

A comparative analysis of the proposed technical solution with identified analogues of the prior art, from which the invention does not explicitly follow for a pyrotechnic specialist, showed that it is not known, and taking into account the possibility of industrial serial production of a metal chloride mixture of a smoke-forming composition, it can be concluded that the patentability criteria are met .

Claims (1)

Pyrotechnic composition for the formation of a smoke mask, containing potassium perchlorate, hexachloroethane, metal fuel and technological additives, characterized in that it contains zinc oxide or zinc white, as a metal fuel it contains aluminum powder with a specific surface area of 0.13-0.38 m ² / g, and as technological additives - chlornairite, plasticized with dibutylsebacinate, and aerosil in the following ratio of components, wt.%:
potassium perchlorate 16-24 hexachloroethane 18-22 aluminum powder 23-27 zinc oxide or zinc white 25-29 chlornairite 3-6 dibutyl sebacinate 1-3 aerosil 1-2