Thermal Analysis of Ammonium Perchlorate and of its Mixtures with Inorganic Substances

Solid mixtures containing ammonium perchlorate diluted with reputedly inert substances SiC, SiO 2 , TiO 2 , Al 2 O 3 and the salts: KCl, NaCl, BaCO 3 , CaCO 3 respectively were studied by TGA and DTA. Undiluted NH 4 ClO 4 and the perchlorates of K, Na, Ba, Ca were also examined. The two known temperature regions of NH 4 ClO 4 thermolysis were confirmed. The first DTA exotherm of NH 4 ClO 4 seems to be related to its limited decomposition; it can be suppressed by an ammonia atmosphere, by thermal cycles, or by heat‐dissipating conditions. The second exotherm is related to the change of the decomposition mechanism of HClO 4 above 330°. TGA rate curves of stoichiometric mixtures of NHClO 4 with salts show two peaks due to decomposition of NH 4 ClO 4 and one peak due to the MeClO 4 formed on heating. The formation of MeClO 4 is confirmed by visual observations and by DTA. Thermal cycles followed by DTA of stoichiometric mixtures of (NH 4 ClO 4 + KCl), (NH 4 ClO 4 + BaCO 3 ) reveal the systematic formation of MeClO 4 at the expense of NH 4 ClO 4 . For (NH 4 ClO 4 + NaCl), (NH 4 ClO 4 + CaCO 3 ) there appear in the vicinity of the transition endotherm of NH 4 ClO 4 new reversible endotherms difcontaining NH 4 ClO 4 . Only after their thermal decomposition do the transition endotherms of MeClO 4 appear.