Mechanism of dissolution of a Cu-13Sn alloy in low aggressive conditions

Corrosion of a synthetic Cu-13Sn alloy with a dendritic structure was investigated in a low aggressive medium (0.01 M Na2SO4 aqueous solution). The corrosion rate was accelerated through anodic polarization of the alloy in a potential range close to the open-circuit potential. The composition of the corrosion layer was followed as a function of the polarization time, using scanning electron microscopy and energy dispersive spectrometry methods. The results clearly showed that bronze corrosion in these experimental conditions proceeds by decuprification. Selective copper dissolution leads to corrosion layers enriched in tin compounds. It was concluded that bronze is partially passivated through the presence of a tin oxide layer, which slows down copper dissolution rate, compared to pure copper