Structural characterization of corrosion product layers on archaeological iron artifacts coming from Vigna Nuova, Crotone (Italy)

A collection of archaeological iron artifacts, whose age could be assigned from the Iron Age up to the post–medieval period, and coming from the Archaeological National Museum of Crotone (Calabria, Italy) were investigated. They show evident forms of degradation although they were restored around twenty years ago. The aim of this work was to study the chemistry of the corrosion layers formed on the iron artifacts. Techniques such as optical and electronic microscopies (OM and SEM-EDS), X-Ray diffraction (XRD), Ion Chromatography, ATR/FTIR Spectroscopy and Micro-Raman Spectroscopy have been applied. It was found that corrosion products are mainly made up of goethite, maghemite, magnetite, hematite, lepidocrocite and ferrihyidrite. Akaganeite was often found at the interface between the corrosion products and the core of the metal. This could be considered as the main cause of the rapid post-restoration deterioration of iron objects investigated.