Heat generating pyrotechnic

Detonators, Initiators, Delay Compositions and Heat-Generating Pyrotechnics... 

Heat-producing pyrotechnic compositions are used in a variety of applications, for example, as first fires in pyrotechnic devices to ignite other materials, as primers, as heat generators in pyrotechnic heaters, as propellants in gas generators and rocket motors, and as incendiary devices. 

Pyrotechnic compositions which are used in primers or first fires are very sensitive to initiation, whereas compositions which are used in heat-generating devices are less sensitive. The sensitivity of the compositions can be controlled by reducing the amount of oxidizer and choosing a less sensitive oxidizer. 

Many other pyrotechnic articles are in use including gas generators, heat generators, theatrical effects (simulated bullets, smoke, flash powder), flashbulbs, airbag inflators, and thermitic welding kits. There is not a clear division between these and certain explosive articles. 

M.A. Bohn, Modelling of the stability, ageing and thermal decomposition of energetic components and formulations using mass loss and heat generation, 2000, Proceed 27 Int. Pyrotechnics Seminar, Grand Junction, Colorado, USA 751-70. 

A pyrotechnic composition contains one or more oxidizers in combination with one or more fuels. Oxidizers used in pyrotechnics, such as potassium nitrate, KNO, are soflds at room temperature and release oxygen when heated to elevated temperatures. The oxygen then combines with the fuel, and heat is generated by the resulting chemical reaction. Chemicals that release fluorine or chlorine on heating, such as polytetrafluoroethylene (Teflon)... 

To produce this type of atomic emission in a pyrotechnic system, one must produce sufficient heat to generate atomic vapor in the flame, and then excite the atoms from the ground to various possible excited electronic states. Emission intensity will increase as the flame temperature increases, as more and more atoms are vaporized and excited. Return of the atoms to their ground state produces the light emission. A pattern of wavelengths, known as an atomic spectrum, is produced by each element. This pattern - a series of lines - corresponds to the various electronic... 

A pyrotechnic reaction generates a substantial quantity of heat, and the actual flame temperature reached by these mixtures is an area of study that has been attacked from both the experimental and theoretical directions. 

Pyrotechnic primer compositions are often used to ignite gun propellants. The primer emits a burst of flame when it is struck by a metal firing pin, igniting the gun propellant. These primer compositions are therefore very sensitive to initiation and are capable of generating heat and shock. In order to reduce the sensitivity during the manufacturing process, the composition is used in the paste form. Examples of pyrotechnic compositions used in primers are presented in Table 8.5. 

Some chromates are used in expl, and pyro-technic compns. Discussions on their uses in pyrotechnic heating devices, pyrochemical gas generators and other pyro items are given in Ellern, Pyrotechnics(l961). 137, 147, 160,... 

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