Combustion characteristics of aluminum hydride at elevated pressure and temperature

A comparison of the combustion characteristics of aluminum hydride and aluminum with respect to combustion time and temperature at elevated pressures in carbon dioxide and oxygen has been performed using a shock tube. For a wide range of oxidizer concentrations, the combustion time of 5-10 mu aluminum hydride is very similar to that of aluminum. Gas-phase temperatures measured by aluminum monoxide (AlO) emission and absorption spectroscopy, as well as solid product temperatures measured by two-color pyrometry, yield very similar values for both materials (to within experimental uncertainty). Observations of hydroxyl (OH) emission behind the incident shock suggest that hydrogen desorbs at temperatures well below the ignition threshold for aluminum. These observations are all consistent with the oxidation of aluminum hydride involving a rapid dehydrogenation step, followed by combustion of the remaining aluminum.