Thermal Decomposition and Kinetics Studies of AN, KDN and Their Mixtures with and without Catalysts

Potassium dinitramide (KDN) was incorporated in ammonium nitrate (AN) crystals in AN/KDN ratio of 90/10, 75/25 and 50/50 by a co-crystallization method. These mixtures were subjected to thermal decompositional studies (DSC-TG) using a Simultaneous Thermal Analyzer (STA). The catalysts used for the present studies were: i) cupric(II) oxide (CuO) and, ii) copper-cobalt based metal oxide (Cu-Co*). For all catalytic samples, 2% by weight percent of catalyst was added to the total weight of the samples. Thermal decomposition studies were carried out for all the oxidizer samples prepared. Thermal decompositional studies were carried out at three different heating rates, i.e. 3 K/min, 5 K/min and 10 K/min, and the kinetic parameters were computed using the model free Flynn-Wall-Ozawa equation. It has been observed that 50% KDN addition resulted in complete suppression of endothermicity indicating total supression of the phase changes of AN in this temperature range. Further, it was noticed that CuO acts as a better phase stabilizer for AN as compared to Cu-Co*. However, Cu-Co* considerably increased the net exothermic decompositional heat release (J/g) of AN.