Decomposition of Aluminum Hydride Under Solid Rocket Motor Conditions

Abstract

The decomposition rate of aluminum hydride powder was measured at slightly elevated temperatures (400-500 K) using the pressure rise due to the released hydrogen. This information is important for understanding the combustion behavior of aluminum hydride when used in propellants and explosives. The thermolysis measurements fit well to an Arrhenius-type exponential fit, with a preexponential of 3.29e9 1/s and an activation energy of 97.6 kJ/mol. Two-dimensional simulations of aluminum particles in a propellant mixture were also performed to determine the temperature and velocity history of the particles in a burning propellant. Using this information and extrapolating the measured dehydrogenation rates, It was determined that alane will decompose before being ejected off of the propellant surface. This prediction suggests that the hydrogen will be available to react in the primary flame zone of the rocket motor, and will thus impact the stoichiometry in this region. The decomposition process could also affect the surface characteristics of the burning propellant.