Microstructure of Aluminum Hydride and Stabilization Concepts

Aluminum hydride (AlH3, alane) is a promising substance for hydrogen and energy storage systems, rocket propellants, and space applications [e. g. 1-4]. The substance is sensitive against humidity and oxidation, and will decompose in air and water, although passivation greatly diminishes the decomposition rate [5]. A high stability variant was produced in former Soviet Russia and was even used in the ballistic missiles SS-24. The material is however not commercially available, and details of the synthesis and production (stabilization) are unknown [6]. Investigations of this product at the Fraunhofer ICT in the early 2000s revealed interesting details, but no conclusive stabilization concepts [7, 8]. With rising new interest for applications of alane in solid rocket propellants at the Fraunhofer ICT, e. g. due to a potential increase of the specific impulse of ADN/GAP propellants by about 10 %, new structure investigations were restarted with modern characterization technologies available today. Besides, new literature contributions have been reviewed including stabilization mechanisms, related microstructures and alane provider [9]. The investigations revealed new structural aspects and stabilization concepts.