Assessment of Cavitation-Erosion Resistance of Potential Pump Impeller Materials for Mercury Service at the Spallation Neutron Source

Using a standard vibratory horn apparatus, the relative cavitation-erosion resistance of a number of cast alloys in mercury was evaluated to facilitate material selection decisions for Hg pumps. The performance of nine different alloys - in the as-cast condition as well as following a case-hardening treatment intended to increase surface hardness - was compared in terms of weight loss and surface profile development as a function of sonication time in Hg at ambient temperature. The results indicated that among several potentially suitable alloys, CD3MWCuN perhaps exhibited the best overall resistance to cavitation in both the as-cast and surface treated conditions while the cast irons examined were found unsuitable for service of this type. However, other factors, including cost, availability, and vendor schedules may influence a material selection among the suitable alloys for Hg pumps.