Corrosion of copper alloys by gaseous uranium hexafluoride

Abstract

The corrosion of electrolytic copper and eight copper alloys in gaseous uranium hexafluoride at a pressure of 15 kPa was investigated. Corrosion–time relationships were established for five temperatures ranging from 50 to 150°C and for exposure times between 5 and 1000 h. Post-corrosion investigations were performed, employing a variety of physical techniques. Electrolytic copper, beryllium copper, and aluminium bronze were found to be the most resistant of the alloys investigated. The uranium containing corrosion products found were the α and β forms of UF₅ and U₂F₉, with the more reactive alloys giving rise to U₂F₉. Changes in corrosion mechanism correlated with changes in the intermediate uranium fluoride formed. Corrosion activation energies were low, compared to conventional oxidation, ranging from 4 to 64 kJ mol⁻¹.