RU2386608C1 - Composition for preparing pyrotechnic elastic material - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to pyrotechnics. The composition for preparing pyrotechnic elastic material contains 8-10 wt % barium chromate, 2-7 wt % potassium perchlorate, 2-7 wt % fluoroplastic F-42, 45-61 wt % titanium powder, 5-8 wt % asbestos and 16-30 wt % titanium dioxide.

EFFECT: preparation of a composition for making pyrotechnic elastic sheet material which can be used for maintaining the required temperature during a given time interval and has the following characteristics: rate of combustion - 20-30 mm/s, specific gas release - 9-31 cm³/g, specific heat dissipation - 470-580 cal/g.

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Description

The invention relates to the field of pyrotechnics and can be used in various devices where it is necessary to maintain the required elevated temperature for a given time interval, for example, in a block of electrochemical elements (ECE) as part of thermal chemical current sources (TCIT).

Known pyrotechnic composition (PTS) / Exothermic composition for heating devices. Patent RU No. 2022953, IPC C0B 33/02, publ. 11/15/94 /, which includes the following components, wt.%: Potassium nitrate 3-10, sodium salt of carboxymethyl cellulose, or methyl cellulose, or technical lignosulfonate 3-10, coal - the rest. The composition may additionally contain 1-3 glycerol and 2-5 potassium perchlorate. The composition is prepared according to the technology adopted in the pyrotechnic production. This composition is intended for heating the drain valves of railway tanks in order to reduce unloading time, as well as for heating food, water, heating tents, shelters, etc. in the absence of electrical and other types of energy. The main disadvantages of the TCP are smoke emission, sparking and uneven heat generation over time. In TCIT, the release of even a relatively small amount of gas is extremely undesirable, since the implementation of high pressure in a sealed housing of a heat battery (TB) leads to the need to make it durable. In addition, such gas as carbon monoxide released during the combustion of PTS at a high working temperature of TB 250-600 ° C interacts with the active substances of the ECE cathode and anode, which leads to a decrease in the useful capacity of the latter and, ultimately, to reduce the operating time TB

Also known pyrotechnic composition / pyrotechnic composition. Patent RU 2091359, IPC C06B 29/04, 33/06, publ. 09/27/97 /, having a low value of specific gas evolution (0.7-4.5) cm ³ / g, an acceptable value of specific calorific value (350-480) cal / g and consisting (wt.%) Of titanium 82-92, aluminum 2-10, potassium perchlorate 6-8. The pyrotechnic composition is prepared by mechanical mixing of the components in the mixer and is intended for use in backup thermal batteries as a heating element, as well as in devices with high heat generation and low specific gas emission. The combustion temperature of the composition is 1900-2000 ° C, the slags are electrically conductive and practically do not change their geometric dimensions. The relatively high value of the burning rate of the specified composition of 250-400 mm / s does not allow using it for the manufacture of heaters capable of maintaining the operating temperature in the device for a sufficiently long time interval.

The closest in technical essence to the claimed solution is a composition for the manufacture of pyrotechnic elastic material / Composition for the manufacture of pyrotechnic elastic material (options). Patent RU 2306306, IPC C06B 33/12, publ. September 20, 2007 /. In the first embodiment, the composition for the manufacture of pyrotechnic elastic material contains (wt.%) Titanium 12-32, barium chromate 48-71, potassium perchlorate 5-20, asbestos powder 3-10 and ftoroplast brand F-42 3-5. In the second embodiment, zirconium 23-26, as well as barium chromate 52-57, potassium perchlorate 6-10, asbestos powder 7-10 and fluoroplastic grade F-42 2-5 are used as a combustible component. The use of the claimed components in these ratios allows you to create an elastic sheet material, characterized by high burning rates. This effect is achieved by compiling a composition close to stoichiometry and the presence of a relatively small amount of a non-combustible component - asbestos. The use of metal powders - titanium or zirconium, oxidizing agents - potassium perchlorate and barium chromate, as well as fluoroplastic F-42 in selected quantities provides high energy performance of the material and high reliability of its combustion. Material made from these compounds is used to initiate pyrotechnic chains. However, elastic sheet material cannot be used to maintain operating temperatures in devices due to high energy characteristics: burning rate of 1000-4000 mm / s, specific gas evolution of 30-50 cm ³ / g, specific heat of 430-900 cal / g. In addition, the slag formed during the combustion of this material does not retain the original geometric dimensions.

The objective of the present invention is to reduce the burning rate and the specific gas emission of sheet elastic material, as well as maintaining the original geometric dimensions of the slag material.

The technical result achieved by using the inventive composition is to manufacture a sheet of flexible pyrotechnic heater with the following parameters and combustion characteristics:

- burning rate - 20-30 mm / s (an order of magnitude lower than that of the prototype);

- specific gas evolution - 9-31 cm ³ / g (less than the prototype);

- specific heat - 470-580 cal / g;

- safety of manufacturing sheet material;

- slag composition does not change the geometric dimensions of the source material.

To solve this problem and achieve a technical result, a composition containing a mixture of powders of titanium, barium chromate, potassium perchlorate, asbestos and fluoroplastic grade F-42, according to the invention, titanium dioxide is additionally introduced in the following ratio of components, wt.%:

BaCrO ₄ 8-10 KClO ₄ 2-7 Ftoroplast F-42 2-7 Ti 45-61 Asbestos 5-8 TiO ₂ 16-30

The use of these components and their ratio allows you to create an elastic sheet material, characterized by relatively low burning rates and low specific gas emission. The use of titanium powder and potassium perchlorate in a selected amount provides high energy performance of the material, as well as high reliability of its ignition. Fluoroplastic F-42 and asbestos are used as part of a comprehensive improvement of the rheological and physical-mechanical characteristics, which allows you to create an elastic sheet material. The introduction of titanium dioxide and the selection of the ratio of the components of the composition can reduce the rate of combustion and specific gas evolution, as well as ensure that the combustion products (slags) maintain the original geometric dimensions of the material. At the same time, a sufficiently high value of specific heat is retained.

For experimental verification of the claimed composition, several compositions were prepared on the basis of the Ti-KClO ₄ -BaCrO ₄ -TiO ₂ -fluoroplast-asbestos system with a different ratio of components, which allows creating a sheet material with a burning rate of 20-30 mm / s, an allowable value of specific gas evolution 9-31 cm ³ / g and specific heat 470-580 cal / g. In addition, the slag composition does not change the initial geometric dimensions of the material. The sheet material is prepared by preparing a suspension based on a solution of fluoroplastic in acetone with the addition of the remaining starting components and the subsequent processes of "filling" into molds, drying and rolling. At the last stage, pyrotechnic sheets of the required shapes and sizes are made (cut) from sheet material. Powders of potassium perchlorate (TU 6-09-3801), titanium (TU 1715-036-07623615) and barium chromate (TU6-09-5286) were used to prepare pyrotechnic tapes. The safety of manufacturing such a material is ensured by the absence of a stage of mechanical mixing in the solid phase of the starting components in various kinds of mechanical mills and mixers.

According to the experimental data presented in table 1, the optimal technical result is observed for the compositions at positions 4-7. Tests of materials from the composition without potassium perchlorate (items 1-3) led to:

- incomplete combustion of the material (position 1);

- poor flammability at low temperatures (position 2);

- not to preserve the slag form of the source material (position 3).

The material from the claimed composition (positions 4-7) after combustion has solid slags that preserve the original form of the material.

According to table 1, the following characteristics are obtained:

- burning rate - 20-30 mm / s;

- specific gas evolution - 9-31 cm ³ / g;

- specific heat - 470-570 cal / g (in argon); 520-580 cal / g (in air).

The experimental verification of the pyrotechnic heater obtained from the claimed composition as an element ensuring the maintenance of the required temperature in the block of electrochemical elements during the operating time as a part of thermal chemical current sources showed positive results, consisting in increasing the operating time of the thermal battery with reliable initiation and combustion of the heater pyrotechnic of the claimed composition.

Claims (1)

Composition for the manufacture of pyrotechnic elastic material containing powders of titanium, barium chromate, potassium perchlorate, asbestos and fluoroplastic F-42, characterized in that it additionally contains titanium dioxide in the following ratio of components, wt.%:
Barium Chromate (BaCrO ₄ ) 8-10 potassium perchlorate (KClO ₄ ) 2-7 ftoroplast F-42 2-7 titanium 45-61 asbestos 5-8 titanium dioxide (TiO ₂ ) 16-30