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A Synchrotron‐Based Study of the Mary Rose Iron Cannonballs
Author(s) -
Simon Hayley,
Cibin Giannantonio,
Robbins Phil,
Day Sarah,
Tang Chiu,
Freestone Ian,
Schofield Eleanor
Publication year - 2018
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201713120
Subject(s) - akaganéite , x ray absorption spectroscopy , corrosion , synchrotron , hematite , metal , x ray photoelectron spectroscopy , chemistry , chlorine , absorption (acoustics) , metallurgy , materials science , inorganic chemistry , absorption spectroscopy , chemical engineering , adsorption , goethite , composite material , optics , physics , organic chemistry , engineering
Post‐excavation iron corrosion may be accelerated by the presence of Cl − , leading to conservation methods designed to remove Cl. This study exploits a unique opportunity to assess 35 years of conservation applied to cast‐iron cannon shot excavated from the Mary Rose. A combination of synchrotron X‐ray powder diffraction (SXPD), absorption spectroscopy (XAS), and fluorescence (XRF) mapping have been used to characterise the impact of conservation on the crystalline corrosion products, chlorine distribution, and speciation. The chlorinated phase akaganeite, β‐FeO(OH,Cl), was found on shot washed in corrosion inhibitor Hostacor IT with or without an additional reduction stage. No chlorinated phases were observed on the surface of shot stored in sodium sesquicarbonate (Na 2 CO 3 /NaHCO 3 ); however, hibbingite, β‐Fe 2 (OH) 3 Cl, was present in metal pores. It is proposed that surface β‐FeO(OH,Cl) formed in the early stages of active conservation owing to oxidation of β‐Fe 2 (OH) 3 Cl at near‐neutral pH.