X-ray photoemission study of soldered lead materials: relevance to the surface and interface chemical composition of Roman lead pipes 'fistulae'

摘要

We have used X-ray photoemission spectroscopy (XPS) to study the surface and interface chemical composition of soldered lead materials obtained using PbSn alloy as a solder and either olive oil or stearin wax as a flux. Apart from thephotoemission transitions, we have also measured the X-ray induced Auger PbNOO transition which expands considerably the scale of probing depths. We find that the main role of the solder is to minimize surface lead oxidation at the joint, although oliveoil and stearin also play a meaningful antioxidizing role. Both fluxes are very effective in minimizing surface hydration, whereas neither affects the content of carbonate species to a greater extent than does the solder itself. These results are compared with previous XPS studies of Roman lead pipes "fistulae1' and with the reports of historical sources.