Inhibition of Pitting Corrosion of Aluminum Bronze in Sodium Chloride Solution

The pitting corrosion of aluminum bronze (Cu-6%Al) has been investigated in sodium chloride (NaCl) solution of different concentrations. Potentiodynamic anodic polarization and galvanic current-time measurements were carried out. The pitting corrosion potential, E_pit, shifts to more negative values and the induction period for initiation of pitting corrosion becomes shorter with the increase of NaCl concentrations. The effect of increasing additions of different organic compounds on the pitting corrosion of the alloy in 0.5 M NaCl solutions was studied. It was found that the presence of these organic compounds in increasing concentrations shifts the E_pit to more positive values and the induction period becomes shorter. The inhibitory effect of the organic compounds greatly depends on the molecular structure and size of the compound, the number of adsorption centers, and the electron density on these adsorption centers. The sulfur-containing organic compounds has the highest inhibitory effect.