The titanic 80 years later: initial observations on the microstructure and biogeochemistry of corrosion products
The “Titanic 91” Expedition, carried out from the Russian Academy of Science vessel “Akademik Keldysh”, recovered artifacts from the wreck of the Titanic using the manned submersible “MIR-2”. Conspicuous corrosion products are iron rusticles resembling stalactites. These rusticles can reach lengths of several tens of cm and grow from various parts of the ship (Fig. 1). The origin of the rusticles and their relation to other corrosion products was investigated using a scanning electron microscope equipped with an x-ray energy dispersive spectrometer and a separate x-ray diffraction system.Rusticles are formed of a brittle iron oxy-hydroxide shell approximately 100 to 200 μm thick, with a smooth dark red outer surface (toward seawater) and an orange rough inner surface (toward the centre of the rusticle). The core of the rusticle and the inner surface of the shell is made of a reticular framework of spherical aggregates. The small needle-like crystals forming these aggregates (Fig. 2) are goethite (α- FeO(OH)).