Preliminary Kinetic Characterization of Lithium-Aluminum Based Hydrides for Airbreathing Propulsion

摘要

The aim of this research is to present a preliminary experimental investigation on the behavior of lithium-aluminum complex hydrides when exposed to gaseous nitrogen in the range of 20-350℃ for airbreathing propulsion applications. This specific task is part of the long-term project devoted to the use of lithium-aluminum hydrides in airbreathing propulsion applications. It is known that a launch system based on the airbreathing technology, by using air as oxidizer, reduces the cost per kilogram of the launch; it is therefore much more profitable than common rocket engines (solid and liquid rockets). The effect of nitrogen gas on the thermal behavior and the kinetic parameters of lithium-aluminum hydride and trilithium-aluminum hydride has been investigated. Differential scanning calorimeter tests, performed using nitrogen gas, have shown the presence of a strong exothermic peak that, when using helium or argon gas, is barely noticeable. A nitridation reaction has been suggested to explain the increase of the sample mass after each differential scanning calorimeter test, which supports the experimental data. The activation energy E_α and frequency factor A for the samples of lithium-aluminum hydride and trilithium-aluminum hydride have been calculated using two simplified kinetic methods: the Ozawa method and the Kissinger method.