Corrosion behaviour of copper under chloride-containing thin electrolyte layer

► Corrosion behaviour of copper under thin electrolyte layers (TEL) with various thicknesses was investigated. ► Corrosion rate increases with decreasing layer thickness during the initial stage. ► Corrosion rate follows the order 300 > 402 > 199 > bulk solution > 101 μm after long time immersion. ► A corrosion model of copper under chloride-containing TEL is proposed. The corrosion behaviour of copper under chloride-containing thin electrolyte layers (TEL) was investigated using electrochemical impedance spectroscopy (EIS), cathodic polarization, linear polarization, SEM/EDS and XRD. The results indicate that the copper corrosion rate increases as TEL thickness decreases during the initial stages. After 192 h of immersion, the corrosion rate of copper under TEL in this order: 300 > 402 > 199 > bulk solution > 101 μm. The corrosion behaviour is uniform under TEL, and pitting is the primary corrosion type in the bulk solution. A corrosion model of the behaviour of copper under chloride-containing TEL is proposed.