If the corrosion rate of tin bronzes can reach 2.2 g/m² per 24 hours in sea water, then why do we find artifacts of antiquity in excellent condition at the bottom of the Mediterranean Sea, why did they not destruct during this time?
If the corrosion rate of tin bronzes can reach 2.2 g/m² per 24 hours in sea water, then why do we find artifacts of antiquity in excellent condition at the bottom of the Mediterranean Sea, why did they not destruct during this time?
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Thank you for the great question. Tin bronze is not a single alloy. Tin bronze is a family of alloys with varying percentages of tin in copper, along with other alloying elements. In ancient bronzes, there were elements like gold, silver, lead, zinc, etc. Hence, the corrosion rate of those bronze anRead more
Thank you for the great question. Tin bronze is not a single alloy. Tin bronze is a family of alloys with varying percentages of tin in copper, along with other alloying elements. In ancient bronzes, there were elements like gold, silver, lead, zinc, etc. Hence, the corrosion rate of those bronze antiques in seawater will not be the same as the tin bronze that you have referred to here.
Further, the corrosion that occurs is not general corrosion as seen in case of steel or iron. The corrosion here is called selective leaching, where the in will dissolve preferentially to the copper. So the mainframe of copper in the antique will still be present with a possible layer of patina(copper oxide) over it. Hence, we do not find a complete dissolution of some antiques in seawater.
Please go through the following link for more information – https://www.sid.ir/en/Journal/ViewPaper.aspx?ID=217881
See lesshttps://heritagesciencejournal.springeropen.com/articles/10.1186/2050-7445-1-21
http://www.getty.edu/publications/artistryinbronze/conservation-and-analysis/36-tykot/
https://exarc.net/issue-2017-2/ea/colour-palette-antique-bronzes-experimental-archaeology-project