Galvanic corrosion between zinc and carbon steel investigated by local electrochemical impedance spectroscopy

International audience; The study of galvanic coupling between two metals is still a relevant topic, particularly in aerospace andautomotive industries. The development of local electrochemical techniques leads to a better understandingof the phenomena occurring at the interfacial zone. Galvanic coupling between carbon steel and zincwas investigated by local electrochemical impedance spectroscopy (LEIS) in a 0.06 g L−1 NaCl solution.Voltammetry and conventional electrochemical impedance experiments were also performed to betteranalyze the local impedance data. Local measurements carried out at a fixed frequency showed that zincdissolution was more significant at the steel/zinc interface. A particular shape of the local impedance diagramwas observed above the zinc surface with the presence of a large inductive loop in the low-frequencyrange. Numerical simulations, performed by using finite element method, allowed the local experimentaldiagrams obtained over the zinc sample to be validated taking into account the radial contribution of thecurrent between both materials in galvanic coupling.