Synergistic effect of chloride and sulfite ions on the atmospheric corrosion of bronze

The effect of chloride along with sulfite ions on the atmospheric corrosion of bronze was investigated by using periodic wet-dry tests, surface tension tests and electrochemical impedance measurements. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to characterize the corrosion products. Both the electrochemical impedance measurements and surface tension tests agreed well with the results of weight loss measurements. Synergistic effect of chloride and sulfite ions was observed during the whole process. In addition, we found that the attack of anions on the metal at the initial corrosion stage showed good agreement with their surface activity. However, as the corrosion proceeded, the interaction among the corrosion products induced by chloride and HSO3- accelerated the corrosion process. A scheme was given to explain the whole corrosion process.