Boiling pyrotechnics

Differential thermal analysis (DTA) has provided a wealth of information regarding the thermal behavior of pure solids as well as solid mixtures [10]. Melting points, boiling points, transitions from one crystalline form to another, and decomposition temperatures can be obtained for pure materials. Reaction temperatures can be determined for mixtures, such as ignition temperatures for pyrotechnic and explosive compositions. 

Finally, a product of a pyrotechnic reaction may vaporize from the reaction zone and subsequently condense as fine particles in air, creating a smoke. Potassium chloride (boiling point 1407°C) produces smoke in many potassium chlorate and potassium perchlorate compositions, although smoke is usually not a goal sought from these mixtures. 

TABLE 5.8 Melting and Boiling Points of Common Non-Gaseous Pyrotechnic Productsa... 

For many years, boiled linseed oil has been used to coat Mg powd to protect it from corrosion when used in pyrotechnics. Mg powd and oil are mixed together and allowed to stand in a warm place in shallow trays for about 48 hours, before the other chemicals are added. Lately there has been a tendency to replace linseed oil with polyesters, or to use no coating at all, but there can be no doubt that linseed oil renders good protection. Stores made with Mg coated with linseed oil are good for several years, which is not the case with uncoated Mg (Refs 2 5). Linseed oil has also been used for coating K chlorate used in expls (Ref 1)... 

In a nutshell, Mg and Al are the most commonly used pyrotechnic fuels to create heat and light. Both have been used in the development of radiation effect. While Mg is the fuel of choice for most illuminating and tracer formulations, Al is still the main ingredient of photoflash and thermite formulations. The pyrotechnic behavior of Mg is due to its low melting and boiling points in comparison to most... 

Shellac, boiled linseed oil, resins, paraffin wax, beeswax, litbographic varnish and acaroid resin are used in various pyrotechnic formulations. Similarly chlorinated rubber powder has also been used successfully as a binder. Some of tbe waxes and resins which are of natural origin are still popular and are in use. In order to improve quahty and avoid batch-to-batch variation, manufacturers of pyrotechnics are moving from natural binders to man-made binders. 

Some of the important properties which are considered when choosing the ingredients for pyrotechnic formulations are density, hygroscopicity, melting and boiling points and decomposition temperatures, oxygen content of oxidizers, thermal conductivity of fuels and containers, nature of combustion products and toxicity etc. 

An aluminum scrap contg ca 4.3% Cu was, shown to be practically as suitable as specification grade A1 for use in some pyrotechnic flares) C) Davis (1943), 134 158 (Cu powder has been used in manuf of some expls. For example, TNB can be obtd by refluxing for 2 hrs picryl chloride with Cu pdr in hot aq ale and HNDPhA can be obtd by boiling picryl chloride in nitrobenzene soln with Cu pdr for a short time) D) L.H. Eriksen,, PATR s 1325 (1945),... 

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