Combustion of HTPB Based Solid Fuels Containing Metals and Metal Hydrides with Nitrous Oxide

An experimental investigation of the combustion characteristics of HTPB-based solid fuels containing aluminum and aluminum hydride has been conducted. Aluminum is commonly used as a fuel supplement in solid rocket propellants because of its ability to increase the specific impulse of a propellant. Similarly, aluminum hydride, or alane, is another attractive fuel supplement because it can significantly (∼7–8 %) increase specific impulse even beyond that of aluminum. In this study, the regression rates of a baseline fuel (pure HTPB) were compared with that of fuels containing either aluminum or alane as additives using a counterflow combustion experiment with nitrous oxide (N₂O) as the oxidizer. The additives were investigated in concentrations of 10, 20, and 40 % by weight of the fuels. The addition of aluminum at all loadings resullted in a decrease in the regression rate relative to the baseline, whereas the addition of alane resulted in at worst similar regression rates and at best (highest loading) approximately a 20 % increase in regression rate. The decomposition behavior of selected fuels was analyzed using traditional thermal analysis techniques; thermal gravimetric analysis and differential scanning calorimetry.