Quantification of Critical Elements

Determination of Elemental Impurities in Delay Compositions

  • Fig.1: From left to right filtered residues after digestion with increasing HF volumes. Left: majority of FexSiCry and no Pb3O4; Middle: insoluble Pb3O4 with traces of FexSiCry; Right: insoluble Pb3O4 and no FexSiCryFig.1: From left to right filtered residues after digestion with increasing HF volumes. Left: majority of FexSiCry and no Pb3O4; Middle: insoluble Pb3O4 with traces of FexSiCry; Right: insoluble Pb3O4 and no FexSiCry

Ferrochrome silicon alloys (FexSiCry) and lead tetroxide (Pb3O4) are commonly used in pyrotechnics for the production of delay charge elements in millisecond electric detonators (DEM). The ignition delay does not only depend on the molar ratio of major elements, but also on purity of raw materials. Therefore, a very accurate and efficient analytical method is needed for quality control.

Introduction
Pyrotechnic compositions aim to develop an acustic (sound), optical (light or smoke), thermical (heat) or mechanical (pressure) effect. Mostly, these are known for civil use as fireworks for amusement. But, the range of applications is even broader. Pyrotechnics are essential for industrial and military use e.g. for desinfestation with smoke set up and exploders in mining or building industries. The crucial step is the spontaneous and exothermic reaction of an oxidizing agent (Pb3O4, Fe3O4, SnO2) with a fuel (reducing agent e.g. FexSiCry, MgxAly, Bi2S3). The mixtures are optimized according to the final application, e.g. by adding catalyst or other additives.

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Berghof Products + Instruments GmbH
Harretstr. 1
72800 Eningen
Phone: +49 7121 894 0
Telefax: +49 7121 894 100

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