Effect of S₂O^2-₃ on Pitting Corrosion of Cu-15Ni-8Sn Alloy in Sodium Chloride Solutions

The pitting corrosion of Cu-15Ni-8Sn alloy in solutions containing different concentrations of NaCl was studied by potentiodynamic polarization method. The results showed that with the increase of Cl- the radius of pits increased significantly, which indicating the decrease of the pitting corrosion resistance of the alloy. Addition of low concentration of Na2S2O3 into the NaCl solution, e.g. 0.001 mol/L, 0.01 mol/L and 0.1 mol/L, can inhibit the pit formation on the alloy surface. However, this inhibiting effect was eliminated when the concentration of Na2S2O3 increased to 1mol/L.