Application of Theoretical Models to the Kinetic Study of the TiFe0,5Co0,5 - H2 System

M. Boulghallat, A. Jouaiti, L. Lallam

Abstract: The reaction of hydrogen with metals to form hydrides has numerous potential energy storage and management applications. But initially it is first necessary to determine conditions of hydrogen sorption kinetics. In this paper the hydriding kinetics of TiFe0, 5Co0.5 are studied. Experiments were carried out in thermo gravimetric microbalance with a high sensibility (2.10-6 g) on a series of isothermal and isobaric measurement. The kinetics models, namely JohnsonMehlAvrami (JMA) model and Jander diffusion model (JDM) are used to explain the obtained results. In the first model, the order of the reaction is assumed as unit and in the second model, the rate constant is calculated by estimating the order by fitting the reaction kinetics data with a reaction kinetics equation. The activation energy and pre-exponential constants of the above-mentioned alloy are estimated by constructing the Arrhenius plot. The absorption mechanism of hydrogen and rate-controlling step of the reaction are estimated for the hydride investigated.

Keywords: Hydriding, kinetics, Modeling, Activation energy, mechanism