Uranium Casting Materials Development: HfN Testing Summary
A total of four dip tests were performed on TerraPower provided HfN coated niobium coupons. However, in the first two tests, excessive oxidation of the charges materials led to inadequate contact between the HfN coated specimens and the molten alloy. The final two tests used a much higher ramp rate, which provided less time for oxidation of the melt. In both of these tests, the dipped specimens appeared fully intact and coated with metal alloy. The alloy could not be easily removed, suggesting either a mechanical interlocking or a chemical bonding. Due to shifting programmatic priorities, metallographic examination of the samples was not performed.