Corrosion of iron in liquid uranium hexafluoride
Résumé
Here is reported a dedicated and reliable experimental setup which has been designed to study the corrosive effects of liquid uranium hexafluoride (UF6) on pure metallic iron at 80°C and 3 bars of pressure. Three corrosion tests have been carried out, ranging from several hundred to almost one thousand hours. No uniform corrosion was observed on early-stage samples. However, a nodule facies consisting in FeF2 and UFx (with 4 < x < 5) deposits is observed at the surface of the iron samples. These FeF2 nodules grow with time and merge, leading finally to the formation of an almost continuous FeF2 layer. The thickness of the layer over time seems to follow a parabolic kinetics law, finally reaching 15 µm after about one thousand hours of immersion in liquid UF6. After the nodules have merged, many cracks can be observed in the FeF2 layer, probably due to the growing stresses as the corrosion layer is formed.