Kinetics of Thermal Decomposition of Aluminum Hydride in Argon
ENGINEERING RESEARCH AND CONSULTING INC(ERC INC) EDWARDS AFB CA
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Thermogravimetric analysis was utilized to investigate the decomposition kinetics of alane AlH3 in argon atmosphere and to shed light on the mechanism of alane decomposition. Two kinetic models have been successfully developed and used to propose a mechanism for the complete decomposition of alane and to predict its shelf-life during storage. Under non-isothermal heating, alane decomposes in two steps the slowest is solely controlled by solid state nucleation of aluminum crystals the fastest is due to growth of the crystals. Thus, during decomposition, hydrogen gas is liberated and the initial polyhedra AlH3 crystals yield final amorphous aluminum particles. Nucleation of aluminum atoms is the rate determining step. After establishing the kinetic model, prediction calculations indicated that alane can be stored in inert atmosphere at temperatures below 10 degrees C for long periods of time e.g. 15 years without significant decomposition. After 15 years storage, the kinetic model predicts 0.1 decomposition. Storage at higher temperatures e.g. 30 degrees C is not recommended.
- Inorganic Chemistry
- Physical Chemistry