Effect of the Nanocrystal Ni0.5Zn0.5Fe2O4 on the Thermal Behavior and Decomposition Reaction Kinetics of Ammonium Perchlorate

摘要

The thermal behavior and non-isothermal decomposition reaction kinetics of the mixture of the nanocrystal Ni0.5Zn0.5Fe2O4 and ammonium perchlorate (AP) were investigated by differential scanning calorimetry (DSC), thermogravimetry and differential thermogravimetry (TG-DTG), and the combination technique of in situ thermolysis cell with rapid-scan Fourier transform infrared spectroscopy (thermolysis/RSFT-IR). The results showed that Ni0.5Zn0.5Fe2O4 can decrease the low-temperature and the high-temperature exothermic peaks of AP by 17.44 K and 27.74 K, respectively, and increase the decomposition heats of the two exothermic peaks by 3.7 J·g-1 and 193.7 J·g-1, respectively. Ni0.5Zn0.5Fe2O4 does not affect the crystal transformation temperature and heat of AP. Ni0.5Zn0.5Fe2O4 makes AP show three mass-loss processes, and it can decrease the initial and terminated temperatures of the last two mass-loss processes. The condensed phase decomposition products analysis shows that Ni0.5Zn0.5Fe2O4 accelerate the decomposition of NH＋4 and restrain the decomposition of ClO-4 in condensed AP. The kinetic parameters Ea = 238.88 kJ·mol-1,A=1018.59 s-1, and the kinetic equation of the high-temperature decomposition reaction of Ni0.5Zn0.5Fe2O4/AP can be described as:dα/dt=18.99(1-α)[-In(1-α)]3/5e-2.87×104/T,The corresponding critical temperatures of thermal explosion (Tbe and Tbp) corresponding to β→0 are 574.83 K and 595.41 K, respectively. The entropy of activation (△ S≠), enthalpy of activation (△H≠), and free energy of activation (△G≠) of the decomposition reaction are 109.61 J·mol-1·K-1, 236.49 kJ·mol-1, and 172.58 kJ·mol-1, respectively.