Surface Preparation of Uranium by Ion Milling

Extract

Metallographic examinations of uranium, as carried out with both optical and orientation contrast microscopies (electron backscatter diffraction or EBSD), typically require a final preparation step that involves acid-etching or electropolishing. Uranium oxidizes relatively rapidly after mechanical polishing, making EBSD impossible without additional preparation steps. Conventional specimen preparation generates a mixture of acids and radioactive waste, so-called “mixed waste” as defined by the Resource Conservation and Recovery Act (RCRA). Mixed waste is more costly to dispose of than either separate component and there is a desire to eliminate mixed waste streams. One simple method to avoid the use of acids in optical metallography is to wait a few minutes for the sample to differentially oxidize to obtain the desired contrast. However, this method is disadvantageous when more than a few micrographs are needed because the sample continues to change with each micrograph.