Corrosion and ESCA studies of uranium after exposure to an RF discharge

Corrosion of uranium in O2 or H2O atmospheres can be inhibited by first oxidizing the surface and then exposing it to organic vapors at temperatures near 4000C. There is evidence that a polymeric material is formed on the surface and that it may be responsible for the corrosion inhibition. Polymer coatings can also be prepared using an RF discharge. This paper describes experiments in which uranium surfaces were exposed to an RF discharge and then evaluated as to their corrosion resistance and surface characteristics. Various plasma gases were used and in each case corrosion inhibition resulted. Samples for corrosion tests and ESCA/Auger examinations were prepared at the same time. The ESCA spectra reveal the formation of hydroxyl groups on uranium surfaces exposed to the RF discharges. Comparisons with corrosion tests suggest that a low surface hydroxyl concentration is associated with a low corrosion rate. The experiments reveal variations in both surface composition and corrosion reactivity which are related to the plasma gas used. These results are discussed in terms of possible reactions occurring between uranium and the RF plasma