DOI: 10.1002/prep.201200183 Binary Flash Compositions – A Theoretical and Practical Study Thomas M. Klapçtke,* [a] F. Xaver Steemann, [a] and Muhammad Suceska [b] 1 Introduction Flash compositions are widely recognized as extremely dangerous pyrotechnic compositions. Despite this, they are used in civil fireworks as well as in military and law enforce- ment applications, e.g. effect simulators [1] or flash gre- nades. Flash compositions comprise a wide field of pyro- technics, containing simple binary compositions of metals (e.g. Al, Mg, Fe), oxidizers [e.g. KClO 3 , KClO 4 , KNO 3 , Ba(NO 3 ) 2 ], and compositions with admixtures of sulfides (e.g. Sb 2 S 3 ), sulfur, or coloring agents. Usually, a composition containing sulfur or sulfide is believed to be easier to ignite, but more prone to self-ignition under moist condi- tions, as well [2]. The contemporary pyrotechnic literature deals with sen- sitivity problems of various flash compositions, most of them containing sulfur or sulfides. Sensitivity against fric- tion, impact, thermal stability (DSC) was studied as well as was the noise output [3]. Using the EXPLO5 computer code [4], the presented study investigates simple binary flash compositions. The thus calculated theoretical detonation parameters have to be compared with practical measurements of explosive performance. The influence of the oxidizing chemical spe- cies and oxidizing agent content on sensitivities as well as on explosive power are to be examined. 2 Results and Discussion Binary compositions consisting of aluminum (aluminum powder and black pyro aluminum) and oxidizing agent (po- tassium chlorate or potassium perchlorate) with oxidizer content of 60 wt-%, 70 wt-%, and 80 wt-% were investigat- ed as well as binary compositions consisting of 30 wt-% aluminum powder and 70 wt-% oxidizer. 2.1 Sensitivities Friction (F r ) and impact (E dr ) sensitivities were measured using BAM apparatus and procedures detailed in reference [5]. Results are listed in Table 1. All compositions were found to be sensitive towards fric- tion and only the aluminum powder based compositions were found to be insensitive towards impact (E dr = 40 J). Compositions based on potassium chlorate were found more sensitive towards impact as well as friction than per- chlorate based compositions. Literature [6] mentions differ- ent values for the potassium perchlorate (70 wt-%)-alumi- num (black pyro) mixture: The reported values indicate a lower impact sensitivity (15 J) but a higher friction sensi- tivity (60 N). With the available data, these values can nei- ther be falsified nor verified. The use of aluminum powder containing 1 wt-% fat to stabilize the fine powder against oxidation or exothermic reactions with moisture decreases the sensitivities of the resulting compositions significantly. The use of fat acts as a lubicrant, which also reduces the sensitivities of the pyrotechnic mixtures. This is further evi- dent by the lower impact and friction sensitivities for the aluminum powder-containing formulations compared to their black pyro-containing aluminum formulations that [a] T. M. Klapçtke, F. X. Steemann Department of Chemistry Energetic Materials Research Ludwig-Maximilian University Butenandtstr. 5–13 (D) 81377 München, Germany *e-mail: tmk@cup.uni-muenchen.de [b] M. Suceska NTU – Chemistry Energetics Research Institute Singapore 639798, Singapore Abstract : Flash compositions are a class of pyrotechnic effect compositions used in firecrackers as well as in milita- ry applications. They are widely recognized as perhaps the most dangerous pyrotechnic compositions. This study in- vestigates binary flash compositions containing aluminum and (per)chlorate oxidizers. The sensitivities of binary flash compositions are measured, their explosive power is com- pared using micro-scale ballistic mortar testing, and their detonation parameters are calculated using the EXPLO5 code. Keywords: Chlorate · Perchlorate · EXPLO5 code · Flash compositions Propellants Explos. Pyrotech. 2013, 38, 29 – 34  2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 29 Full Paper