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Corrosion of brass-iron artifacts from the Akko 1 shipwreck (Israel)
- Ashkenazi(1), A. Inberg(2), D. Cvikel(3)
(1) School of Mechanical Engineering, Tel Aviv University (2) School of Electrical Engineering, Tel Aviv University (3) Leon Recanati Institute for Maritime Studies, University of Haifa
The study of metal archaeological objects can improve our understanding of long-term corrosion in a variety of environments. For metal archaeological artefacts retrieved from an underwater atmosphere, it is most important to understand why some objects are well preserved, while others suffer from severe corrosion.
Two complex systems of objects retrieved from the Akko 1 shipwreck: the brass-iron-wood of a flintlock musket, and brass-iron of a brass case, both dated to the early 19th century, were studied using metallurgical analysis. Both artefacts were covered with encrustation and concretion. The iron musket barrel and the iron nails had corroded completely away by interaction with the marine surroundings, only corrosion products and oxides remaining. However, the brass case, the brass musket ramrod pipe, and the wood texture were survived.
The compositions of the iron and brass oxides indicated that there had been several changes in the environment, including pH, temperature and Cl– and O2 concentrations, during the long immersion in seawater. In the case of the brass-iron galvanic systems, the iron was sacrificed to protect the brass; and although the iron musket barrel and the iron nails did not survive, the brass ramrod pipe, brass case and the wood texture were well preserved.
Such information regarding complex metal electrochemical systems in marine environments contributes to the future conservation process of similar objects.
