Artificial patinas analyzed with PIXE method

Aiming at the restoration and conservation of the archaeological metallic objects, the artificial patinas can be used to simulate the natural patinas (corrosion products in metal and its alloys), permitting the characterization and corrosion mechanisms studies. The natural patinas formation is difficult to study because of the long corrosion production process in materials which take years to be formed. On the other hand the artificial patinas can be easily produced in a shorter time, moreover, they can be used as simulation of the corrosion process and in substitution of monuments and old art objects, damaged for some reason. In our study artificial patinas were produced over pellets of copper and bronze with sulfate, chloride and nitrate solutions and were analyzed with PIXE (Proton Induced X-Ray Emission) technique to supply qualitative and quantitative information of the corrosion elements. The quantitative PIXE analysis takes into account the incident ion beam absorption and the emergent X-ray of the sample, as well as the patina layer and the backing. The PIXE results have shown the presence of S, Cl and Fe and some other elements already known form the backings, such as Cu, Sn, etc. PIXE measurements were also realized in reference metallic materials. (author)