Future from the Past: Long-Term Corrosion of Iron Analyzed Using Bimodal Neutron and X-ray CT

Advancements in analyzing iron archaeological artifacts are helpful in many applications, i.e., elucidating corrosion phenomena experienced by nuclear waste repositories and lifetime prediction of still-buried objects, such as pipelines. This paper investigates the corrosion state of iron-based archaeological objects through bimodal neutron and X-ray computed tomography, SEM-EDX analysis, and Raman spectroscopy. The nail BdC2, excavated from the archaeological site Bois de Châtel in Switzerland, is used as a representative case study. The workflow, starting from securing the sample from the archaeological site, beamtime experiment parameters, and data processing steps until segmentation results validation, is described in this paper. For the segmentation validation, SEM-EDX and Raman spectroscopy analyses were performed. The K-means segmentation algorithm produced satisfying results despite a mis-segmentation of one gap space between two parts of the nails. The work described in this paper is part of a larger analytical system development that aims to enable 3D physical/geometrical reconstruction and chemical composition identification and distribution within ferrous objects via bimodal neutron and X-ray computed tomography experiments, eliminating the need for invasive characterization methods.