Electrochemical and passive behaviour of Cu–Sn bronze in simulated archaeological soil media

Abstract

AbstractThe influence of formation potential on the electrochemical behaviour and passive film properties of Cu‐28.6Sn bronze in simulated archaeological soil solutions was evaluated using combined potentiodynamic electrochemical measurements, electrochemical impedance spectroscopy, and the Mott–Schottky (MS) approach, with ex situ surface analytical techniques such as X‐ray photoelectron spectroscopy. Passive films were formed in sodium chloride (NaCl) solution and a mixture of NaCl and sodium sulphate and their stability increased as the applied potential increased. The MS measurements indicated that a very thin p‐ and n‐type porous passive film was formed on the bronze in the NaCl and sodium sulphate solution. The calculated donor density decreased exponentially with increasing passive film formation potentials in the NaCl solution and in the NaCl and sodium sulphate mixture. Based on the evaluations of the surface compositional analysis, the primary constituents of the films are Cu and Sn; in addition, dehydration of films was noted.