Evaluation of the kinetics and mechanisms of hybriding reactions

Abstract

A scheme for a kinetic study of the hydriding reactions of metals is presented. This scheme is based on a combined kinetic and metallographic study of hydride formation in metallic samples with well defined geometrical shapes. Since the directly measured kinetic quantity (which is the overall reaction rate) depends also on parameters which are not related to the intrinsic nature of the reaction (i.e., on the geometrical shape of the sample and on the topochemistry of the product development) an intrinsic kinetic parameter IKP, should be evaluated in order to characterize uniquely a given reacting system. The choices for these intrinsic parameters and the methods for their evaluation are presented. Different theoretical models for the hydriding reactions are summarized and the predicted pressure-temperature dependence of the IKP's are discussed in light of these models. In some cases the comparison between the experimental and theoretical pressure-temperature behavior may elucidate the mechanisms controlling the respective reactions.