Abstract
The conditions under which insulating oxide films can be formed on uranium by anodic oxidation have been investigated, and a number of experimental techniques has been developed for controlling the conditions of formation and for estimating film thickness during the growth of the layer. A survey of a range of possible anodising electrolytes has been carried out and it is shown that consistent anodising is only obtained within the ternary electrolyte system ammonia-water-glycol. A detailed account of the anodic oxidation in this electrolyte of uranium having different degrees of purity is described. Film formation on uranium is found to be critically dependent not only on the electrolyte composition and the mode of surface preparation, but also on the purity of both electrolyte and metal. The physical and chemical properties of the films have been investigated. The film is found to consist of a nearly amorphous material whose composition lies between UO[2.3] and UO[2.7], depending upon the purity of the metal used. The results obtained are more complex than those which have been noted in other studies of anodic oxidation, and it has not been found possible to account for the kinetics of film formation by applying the theory of Cabrera and Mott.