Effects of Select Metal Oxides on the Onset, Rate and Extent of Low Temperature Ammonium Perchlorate Decomposition

Ammonium perchlorate (AP) is the most abundant ingredient in many solid rocket motors and presents a thermal runaway hazard. The addition of metal oxides (MOs) can alter motor performance but may affect decomposition behavior. In this work, a total of 14 MOs, mostly transition metal oxides, were mixed with AP and subjected to isothermal thermogravimetric analysis (TGA). MOs commonly incorporated into AP-based propellants can alter AP decomposition rates, the extent of reaction, and the particle size of the AP itself. Partially decomposed AP showed significant changes in terminal particle size. There is an inverse correlation between MO lattice energy and peak reaction rates of AP/MO mixtures. The objective of this work is not to provide definitive details of mechanisms, but rather to report observations and interactions with a wide variety of MOs, often ones that were not previously reported. The findings have implications for the safe storage of AP and the development of insensitive motors.