Investigation of the Effect of Iron Oxide on the Burning Rate Temperature Sensitivity of Solid Composite Propellants

The temperature sensitivity of solid propellant burning rate directly affects the accuracy and performance of the rocket motor. In this study، the effect of additives such as iron oxide (IO) on burning rate temperature sensitivity of solid composite propellants based on HTPB was investigated by burning rate، DTA، density and auto ignition temperature experiments. Also the effect of various coarse to fine ratios of oxidizer ammonium per chlorate on temperature sensitivity was studied. The experimental results showed that the burning rates of these propellants were increased by addition of iron oxide or decreasing coarse to fine ratios of ammonium per chlorate particles. DTA results indicated that decomposition temperatures of AP were decreased by addition of iron oxide. Also the auto ignition temperatures of AP with iron oxide were decreased according to the results of auto ignition temperature test. The results also showed that the burning rate temperature sensitivity of AP/HTPB based propellants was reduced by addition of IO or decreasing coarse to fine ratios of ammonium per chlorate particles. The enhancement of burning surface temperature of AP/HTPB/IO and AP/HTPB with low coarse to fine ratios is responsible for the reduced temperature sensitivity. Very small values of the temperature sensitivity are seen when fine AP particles and IO are mixed together.