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Investigation on the Reaction of Powdered Tin as a Metallic Fuel with Some Pyrotechnic Oxidizers



Thermogravimetry (TG), differential thermal analysis (DTA), and differential scanning calorimetry (DSC) have been used to examine the thermal behavior of Sn+KClO3, Sn+KNO3, and Sn+KClO4 pyrotechnic systems and the results were compared with thermal characteristics of individual constituents. TG curves for tin powder, heated alone in air, showed a relatively slow oxidation above 570 °C. From thermal results the decomposition temperatures of KClO3, KClO4, and KNO3, in nitrogen atmosphere, were measured at 472, 592 and 700 °C, respectively. For the Sn+KNO3 pyrotechnic system, the tin oxidation was completed within the range of 480 to 500 °C. Replacing KNO3 with KClO4 led to an increase of thermal stability of the pyrotechnic mixture. Among above-mentioned pyrotechnic mixtures, Sn+KClO3 has the lowest ignition temperature at about 390 °C. The apparent activation energy (E), ΔG#, ΔH# and ΔS# of the combustion processes were obtained from the DSC experiments. Based on these kinetic data and ignition temperatures, the relative reactivity of these mixtures was found to obey in the following order: Sn+KClO3>Sn+KNO3>Sn+KClO4.