Lehmann abstract 2007
Non-destructive and semi-non-destructive analysis of antique and medieval alloys using the example of antique Roman and late medieval European silver ingots: Robert Lehmann, Gottfried Wilhelm Leibnitz Universitat, Hannover
Representatively for antique and medieval alloys, several Roman and late medieval silver ingots were examined for their material properties and characteristic production features. The results permitted conclusions on the different production methods in the single epochs, the raw materials used and the intended purposes of the particular ingots.
Some unexpected results were found, concerning the traces of the production process as well as the local assignment of the used raw materials which points to an active circulation of the silver. In addition differences in the inhomogenities of the alloys were discovered which indicate unusual methods of the medieval casting technology. Matters of appropriate preservation as well as restoration and stock conditions (e.g. display case climate) have also been dealt with and recommendations were given.
The results obtained by chemical and physico-chemical investigations of the historical alloys, that move between a monetary form and a material raw form, contribute to a clarification of economical-historical questions of numismatics. The results can also help to integrate such important objects better into numismatic exhibitions and thus to impart their unique cultural value to the visitors.
Among the analytical methods applied were µ-X-ray fluorescence analysis, tomography with linear accelerator X-rays, scanning electron microscopy, conductivity measurements, atom emission spectroscopy with ICP and confocal microscopy. For the local assignment of the raw materials lead isotope ratios and trace element concentrations were used after sampling of only few micrograms of the material by Laserablation-Q-ICP-MS.
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