Correlative microscopy and Micro-Raman spectroscopy for enhancing the evaluation of corrosion damage in archaeological objects

In this work, we employed correlative imaging techniques to investigate the complex corrosion systems in nails from the Phoenician-Punic site of Motya (Sicily, Italy), combining analytical chemistry and imaging tomography across multiple dimensions and scales. To accomplish this, we used correlative light and electron microscopy, micro-Raman spectroscopy, and X-ray microscopy. The results showed remarkable differences in the condition of the nails, with one nail well-preserved and thinly coated with oxyhydroxides, while the other nail exhibited extensive corrosion and degradation with distinct corrosion layers and the presence of soil minerals. Multiscale X-ray microscopy provided 3D imaging of the internal structures, revealing cracks and the original shape of the nails. This work contributes to the understanding of stress corrosion in metals and has implications for the development of strategies to prevent and control corrosion processes.