Infrared thermography for the thermal diffusivity evaluation in Sn-Pb bronze alloys: a tool for the investigation of ancient statuary

In this work, we report on the application of Pulsed Infrared Thermography for the analysis of the thermal diffusivity dependence on the composition of copper alloys with a tin (Sn) and lead (Pb) concentration typical of ancient bronze artefacts. To this aim, specifically prepared bronzes samples have been investigated. Both the measured thermal diffusivity values and those retrieved from the literature showed a decreasing trend with increasing Sn and Pb concentration. In the overall data analysis, the concentration of Pb atoms was weighted by a coefficient to account for their lower efficiency in reducing the thermal transport properties of the alloy with respect to the Sn atoms. Electrical conductivity values measured on the same samples showed a dependence very similar to that obtained for the thermal conductivity, pointing out the mainly electronic nature of the thermal conductivity in such samples.