Exploring Mechanisms of Particle Size Effects of Iron Oxide on Thermal Behaviors and Combustion Characteristics for 5AT/Sr(NO_3)_2 Propellant

摘要

The effects of composite processing of nano-sized and micron-sized Fe_2O_3 based on 5AT/Sr(NO_3)_2 propellant on catalytic activity, on thermal decomposition, on exhaust temperature, and on the burning rate of the composite propellant are investigated in this paper. From the perspective of application into the solid propellant gas generators for fire fighting technology, micron-sized Fe_2O_3 particles are found to achieve much better modifying effect than nano-sized Fe_2O_3. According to the macroscopic scale experimental results, for the same pressure condition, the burning rate for 5AT/Sr(NO_3)_2 propellant with the addition of micron-sized Fe_2O_3 occur faster with better burning stability than nano-sized Fe_2O_3. The cooling effect for micron-Fe_2O_3 perform also very well with a decrease in peak flame temperature up to 449.9 °C. According to the microscopic scale experimental results, compared with the nano-sized Fe_2O_3, a better dispersion effect in the SEM tests, a lower decomposition temperature, and a smaller combustion cloud in high speed imaging tests have been found out for micron-sized Fe_2O_3. Combined the macroscopic and microscopic measurements, we conclude that the differences in modifying effect is mainly due to the serious aggregation effect of nano-sized particles, including strong inter-particle forces, and coverage effect between particles. The results show that for nano-sized Fe_2O_3 catalysts, their surfaces need to be reprocessing to prevent aggregation to be applied in 5AT/Sr(NO_3)_2 propellant for fire-extinguishing.