The kinetics of the reactions between uranium metal, H2, HD and D2 have been examined. There is strong evidence that the reaction involves several steps of which activated adsorption of the gas by the metal is the rate governing process. Rate constants have been determined for the over-all processes in the temperature range 27.5 deg to 75 deg C. Energies of activation which are of reasonable magnitude have been calculated being 10,200 calories for the process involving D2, 8,500 calories for the process involving HD and 8,200 calories for the process involving H2. From a consideration of the zero point energies for these three molecular species of hydrogen, these results follow in the right order. However because of the adsorption step and since it is not possible to determine the heat of adsorption it is impossible to state that the observed activation energies are the true activation energies. Since the heat of adsorption during the process must be considered in the final interpretation of the results, the true activation energies are probably less positive than those observed. The adsorption step in the processes also accounts for the fact that the ratios of the rates of the reactions, which may be expected to differ inversely as the square roots of the reduced masses of the gas molecules, deviate somewhat from the theoretical values. Heterogeneous reactions such as those reported by this thesis do not lend themselves readily to kinetics experiments. Because of the reactivity of the uranium-hydrogen system it was not possible to determine to what extent the heat of adsorption enters into the values obtained for the observed activation energies. However other metal-hydrogen systems which do not interact so rapidly should better lend themselves to studies of this nature.

Metal Hydrides focuses on the theories of hydride formation as well as on experimental procedures involved in the formation of hydrides, the reactions that occur between hydrides and other media, and the physical and mechanical properties of the several classes of hydrides. The use of metal hydrides in the control of neutron energies is discussed, as are many other immediate or potential uses, e.g., in the production of high-purity hydrogen and in powder metallurgy. It is hoped that this book will serve as a valuable reference to students, research professors, and industrial researchers in metal hydrides and in allied fields. Selected chapters may serve specialists in other fields as an introduction to metal hydrides. The information contained herein will also be of lasting and practical value to the metallurgist, inorganic chemist, solid-state physicist, nuclear engineer, and others working with chemical or physical processes involving metal-hydrogen systems.