Electrochemical behaviour of ancient-like ternary Cu alloys in aqueous chloride media

摘要

In this work the complex and heterogeneous processes -and the basic electrochemical and chemical parameters- involved in the corrosion of ancient bronzes exposed in various chloride-rich environments (such as marine, urban polluted atmospheres, as well as burial in coastal sites) have been studied. Two ancient-like cast bronzes and copper have been employed for potentiodynamic tests in several chloride containing electrolytes. The alloying elements, tin and lead, and the inhomogeneity of the castings microstructures (dendritic segregation, distinct zones on the electrode surfaces and shrinkage effects) cause deviations from the existing models of a bronze electrochemical behaviour in the presence of chlorine species, but the basic corrosion patterns can be regarded as common for ancient-like bronzes and synthetic alloys. It was also found, that Cl-rich soil and atmospheric context, could potentially cause more severe corrosion of copper-based artefacts than plain chloride attack in marine environment.