Abstract
One of the most challenging tasks in the field of light‐producing pyrotechnics is the generation of saturated blue light with high spectral purity. Only copper salts in combination with chlorine seem to be high‐performing blue light emitters. However, in modern pyrotechnics the application of chlorine should be avoided. Different strategies are presented to further fine‐tune literature‐known chlorine‐free blue‐light‐emitting pyrotechnical compositions. The copper iodate as well as the copper bromate systems have been studied by using small amounts of nitrogen‐rich compounds like 1,2,4‐triazole, 5‐amino‐1H‐tetrazole or 3‐nitro‐1H‐1,2,4‐triazole. To overcome sensitivity issues, a two‐component epoxy binder system was introduced. The application of both copper(I) iodide and copper(I) bromide in the same pyrotechnical formulation were considered as blue‐light‐emitting species. Further, a quite new approach by using copper(I) nitrogen‐rich coordination compounds was investigated to give a blue flame color. All relevant formulations were characterized with respect to their dominant wavelength and spectral purity as well as impact and friction sensitivity.
Highlights
One of the most challenging tasks in the field of light-producing pyrotechnics is the generation of saturated blue light with high spectral purity
The Cu(IO3)2 system by Klapötke et al was chosen as starting point for further investigations
The hint of a small blue flame was only detected at the very beginning of ignition stage and disappeared quickly
Summary
PBBs might accumulate in the environment and were found to cause cancer in selected animal studies.[9c]. Since all mixtures should be safe in handling, storing and preparing, the sensitivity as well as toxicity should be considered. Formulations which guarantee safe handling are likely to be produced on a larger scale. Shifted to the Cu(BrO3) system, which was supposed to show bigger potential for improvement regarding the spectral purity and dominant wavelength. Achieved lower spectral purities (SP ≤38 %)[2b] compared to Klapötke's Cu(IO3) system as well as the literature-known publication by Shimizu applying undesired potassium perchlorate, copper, poly(vinyl chloride) (PVC) and starch (Table 1).[2c]. Shimizu′s formulation shows comparatively high impact sensitivity (8 J), but is less sensitive towards friction
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